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Sample records for aluminum perovskite lualo3

  1. Growth and luminescence properties of Pr3+-doped single crystalline films of garnets and perovskites

    International Nuclear Information System (INIS)

    Gorbenko, V.; Zorenko, Yu.; Savchyn, V.; Zorenko, T.; Pedan, A.; Shkliarskyi, V.

    2010-01-01

    Peculiarities of growth of single crystalline films (SCF) of Pr 3+ doped Y 3 Al 5 O 12 and Lu 3 Al 5 O 12 garnets and YAlO 3 and LuAlO 3 perovskites by the liquid phase epitaxy method from melt-solutions based on PbO-B 2 O 3 flux as well as luminescent and scintillation properties of these SCFs were studied in this work. Dependence the intensity of the Pr 3+ d-f and f-f-luminescence on the activator concentration and influence of Pb 2+ flux dopant on the light yield of SCFs of the mentioned garnets and perovskites were analyzed.

  2. Hydrothermal synthesis and characterization of polycrystalline gadolinium aluminum perovskite (GdAlO3, GAP

    Directory of Open Access Journals (Sweden)

    N. Girish H.

    2015-06-01

    Full Text Available Gadolinium aluminum perovskite (GdAlO3, GAP is a promising high temperature ceramic material, known for its wide applications in phosphors. Polycrystalline gadolinium aluminum perovskites were synthesized using a precursor of co-precipitate gel of GdAlO3 by employing hydrothermal supercritical fluid technique under pressure and temperature ranging from 150 to 200 MPa and 600 to 700 °C, respectively. The resulted products of GAP were studied using the characterization techniques, such as powder X-ray diffraction analysis (XRD, infrared spectroscopy (IR, scanning electron microscopy (SEM and energy dispersive analysis of X-ray (EDX. The X-ray diffraction pattern matched well with the reported orthorhombic GAP pattern (JCPDS-46-0395.

  3. Electron traps and scintillation mechanism in YAlO3:Ce and LuAlO3:Ce scintillators

    International Nuclear Information System (INIS)

    Wojtowicz, A.J.; Glodo, J.; Drozdowski, W.; Przegietka, K.R.

    1998-01-01

    In this paper we present the results of thermoluminescence, isothermal decay and scintillation light yield measurements on two isostructural scintillator materials, YAlO 3 :Ce and LuAlO 3 :Ce. In addition to the variety of deep traps identified by thermoluminescence and isothermal decays, scintillation light yield experiments demonstrate the presence in both materials of a number of relatively shallow traps. While the deep traps may reduce the scintillation light yield, they do not influence the kinetics of the process. The shallow traps, on the other hand, by interfering with the process of radiative recombination of charge carriers via Ce 3+ ions, can strongly affect not only the yield of the scintillation process but its kinetics as well. The presence of shallow traps provides a consistent explanation for a number of poorly understood relationships between the two scintillator materials, including a higher room temperature scintillation light yield and longer scintillation decay time in YAlO 3 :Ce, and a longer scintillation rise time in LuAlO 3 :Ce. Theoretical analysis indicates that elimination of these traps would make the two materials nearly identical in scintillator performance. Although the specific identity of all traps remains elusive, the performance of both scintillator materials is now, in practical terms, fully understood. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Progress in the development of LuAlO3 based scintillators

    CERN Document Server

    Belsky, A; Lecoq, P; Dujardin, C; Garnier, N; Canibano, H; Pédrini, C; Petrosian, A

    2000-01-01

    LuAlO3:Ce3+ (LuAP) and LuxY1-xAlO3:Ce3+ (LuYAP) crystals are the promote scintillation materials for Positron Emission Tomography. Actual study of these scintillators develops in the tree directions: (i) growth of large size LuAP crystals with stable properties, (ii) relationship between composition of LuYAP crystals and scintillation properties, and (iii) scintillation mechanisms in lutetium compounds. After improving of growth conditions a large size samples (length greater than 40 mm) have been prepared. Crystals show a good correlation between growth parameters, light yield and transmission spectra. We performed a series of samples with calibrated size (2x2x10 mm3) and compare the light yield with a standard BGO and LSO samples. Mixed crystals with composition of 0.6 less than x less than 0.8 show a significant increase of light yield. We suggest that the short order clusterisation in mixed crystals may by playing an important role in governing the scintillation efficiency. In order to clarify the scintil...

  5. Influence of lead-related centers on luminescence of Ce3+ and Pr3+ centers in single crystalline films of aluminium perovskites and garnets

    International Nuclear Information System (INIS)

    Babin, V.; Gorbenko, V.; Krasnikov, A.; Makhov, A.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

    2010-01-01

    Luminescence characteristics of Ce 3+ - and Pr 3+ -doped aluminium perovskite (LuAlO 3 , YAlO 3 ) and garnet (Lu 3 Al 5 O 12 , Y 3 Al 5 O 12 ) single crystalline films, prepared by the liquid phase epitaxy method with the use of the PbO-based flux, were investigated by the time-resolved spectroscopy methods in the 80-300 K temperature range. The influence of various lead-related centers on the characteristics of the Ce 3+ - and Pr 3+ -related luminescence centers was studied. It was found that the presence of lead-related centers in the single crystalline films results in a decrease of the quantum efficiency and appearance of undesirable slow components in the luminescence decay kinetics. The possibilities of improving the scintillation characteristics of the single crystalline films were considered.

  6. (La1-xSrx)0.98MnO3 perovskite with A-site deficiencies toward oxygen reduction reaction in aluminum-air batteries

    Science.gov (United States)

    Xue, Yejian; Miao, He; Sun, Shanshan; Wang, Qin; Li, Shihua; Liu, Zhaoping

    2017-02-01

    The strontium doped Mn-based perovskites have been proposed as one of the best oxygen reduction reaction catalysts (ORRCs) to substitute the noble metal. However, few studies have investigated the catalytic activities of LSM with the A-site deficiencies. Here, the (La1-xSrx)0.98MnO3 (LSM) perovskites with A-site deficiencies are prepared by a modified solid-liquid method. The structure, morphology, valence state and oxygen adsorption behaviors of these LSM samples are characterized, and their catalytic activities toward ORR are studied by the rotating ring-disk electrode (RRDE) and aluminum-air battery technologies. The results show that the appropriate doping with Sr and introducing A-site stoichiometry can effectively tailor the Mn valence and increase the oxygen adsorption capacity of LSM. Among all the LSM samples in this work, the (La0.7Sr0.3)0.98MnO3 perovskite composited with 50% carbon (50%LSM30) exhibits the best ORR catalytic activity due to the excellent oxygen adsorption capacity. Also, this catalyst has much higher durability than that of commercial 20%Pt/C. Moreover, the maximum power density of the aluminum-air battery using 50%LSM30 as the ORRC can reach 191.3 mW cm-2. Our work indicates that the LSM/C composite catalysts with A-site deficiencies can be used as a promising ORRC in the metal-air batteries.

  7. Growth of MAPbBr3 perovskite crystals and its interfacial properties with Al and Ag contacts for perovskite solar cells

    Science.gov (United States)

    Najeeb, Mansoor Ani; Ahmad, Zubair; Shakoor, R. A.; Alashraf, Abdulla; Bhadra, Jolly; Al-Thani, N. J.; Al-Muhtaseb, Shaheen A.; Mohamed, A. M. A.

    2017-11-01

    In this work, the MAPbBr3 perovskite crystals were grown and the interfacial properties of the poly-crystalline MAPbBr3 with Aluminum (Al) and Silver (Ag) contacts has been investigated. MAPbBr3 crystals are turned into the poly-crystalline pellets (PCP) using compaction technique and the Al/PCP, Al/interface layer/PCP, Ag/PCP, and Ag/interface layer/PCP contacts were investigated. Scanning Electron Microscopic (SEM), Energy-dispersive X-ray spectroscopy (EDX) and current-voltage (I-V) characteristic technique were used to have an insight of the degradation mechanism happening at the Metal/perovskite interface. The Ag/PCP contact appears to be stable, whereas Al is found to be highly reactive with the MAPbBr3 perovskite crystals due to the infiltration setback of Al in to the perovskite crystals. The interface layer showed a slight effect on the penetration of Al in to the perovskite crystals however it does not seem to be an appropriate solution. It is noteworthy that the stability of the underlying metal/perovskite contact is very crucial towards the perovskite solar cells with extended device lifetime.

  8. Temperature-independent sensors based on perovskite-type oxides

    International Nuclear Information System (INIS)

    Zaza, F.; Frangini, S.; Masci, A.; Leoncini, J.; Pasquali, M.; Luisetto, I.; Tuti, S.

    2013-01-01

    The need of energy security and environment sustainability drives toward the development of energy technology in order to enhance the performance of internal combustion engines. Gas sensors play a key role for controlling the fuel oxygen ratio and monitoring the pollution emissions. The perovskite-type oxides can be synthesized for an extremely wide variety of combinations of chemical elements, allowing to design materials with suitable properties for sensing application. Lanthanum strontium ferrites, such as La 0.7 Sr 0.3 FeO 3 , are suitable oxygen sensing materials with temperature-independence conductivity, but they have low chemical stability under reducing conditions. The addition of aluminum into the perovskite structure improves the material properties in order to develop suitable oxygen sensing probes for lean burn engine control systems. Perovskite-type oxides with formula (La 0.7 Sr 0.3 )(Al x Fe 1−x )O 3 was synthesized by the citrate-nitrate combustion synthesis method. XRD analyses, show that it was synthesized a phase-pure powder belonging to the perovskite structure. Aluminum affects both the unit cell parameters, by shrinking the unit cell, and the powder morphology, by promoting the synthesis of particles with small crystallite size and large specific surface area. The partial substitution of iron with aluminum improves the chemical stability under reducing gas conditions and modulates the oxygen sensitivity by affecting the relative amount of Fe 4+ and Fe 3+ , as confirmed from TPR profiles. In the same time, the addition of aluminum does not affects the temperature-independent properties of lanthanum strontium ferrites. Indeed, the electrical measurements show that (La 0.7 Sr 0.3 )(Al x Fe 1−x )O 3 perovskites have temperature-independence conductivity from 900 K

  9. Temperature-independent sensors based on perovskite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zaza, F.; Frangini, S.; Masci, A. [ENEA-Casaccia R.C., Via Anguillarese 301, 00123 S.Maria di Galeria, Rome (Italy); Leoncini, J.; Pasquali, M. [University La Sapienza, Piazza Via del Castro Laurenziano 7, 00161 Rome (Italy); Luisetto, I.; Tuti, S. [University RomaTre, Rome 00146 (Italy)

    2014-06-19

    The need of energy security and environment sustainability drives toward the development of energy technology in order to enhance the performance of internal combustion engines. Gas sensors play a key role for controlling the fuel oxygen ratio and monitoring the pollution emissions. The perovskite-type oxides can be synthesized for an extremely wide variety of combinations of chemical elements, allowing to design materials with suitable properties for sensing application. Lanthanum strontium ferrites, such as La{sub 0.7}Sr{sub 0.3}FeO{sub 3}, are suitable oxygen sensing materials with temperature-independence conductivity, but they have low chemical stability under reducing conditions. The addition of aluminum into the perovskite structure improves the material properties in order to develop suitable oxygen sensing probes for lean burn engine control systems. Perovskite-type oxides with formula (La{sub 0.7}Sr{sub 0.3})(Al{sub x}Fe{sub 1−x})O{sub 3} was synthesized by the citrate-nitrate combustion synthesis method. XRD analyses, show that it was synthesized a phase-pure powder belonging to the perovskite structure. Aluminum affects both the unit cell parameters, by shrinking the unit cell, and the powder morphology, by promoting the synthesis of particles with small crystallite size and large specific surface area. The partial substitution of iron with aluminum improves the chemical stability under reducing gas conditions and modulates the oxygen sensitivity by affecting the relative amount of Fe{sup 4+} and Fe{sup 3+}, as confirmed from TPR profiles. In the same time, the addition of aluminum does not affects the temperature-independent properties of lanthanum strontium ferrites. Indeed, the electrical measurements show that (La{sub 0.7}Sr{sub 0.3})(Al{sub x}Fe{sub 1−x})O{sub 3} perovskites have temperature-independence conductivity from 900 K.

  10. Preparation of aluminum doped zinc oxide films with low resistivity and outstanding transparency by a sol–gel method for potential applications in perovskite solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xingyue; Shen, Heping; Zhou, Chen [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 10084 (China); Lin, Shiwei [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Hainan University, Haikou 570228 (China); Li, Xin [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 10084 (China); Zhao, Xiaochong [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 10084 (China); Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907 (China); Deng, Xiangyun [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Hainan University, Haikou 570228 (China); College of Physics and Electronic Information, Tianjin, Normal University, Tianjin 300387 (China); Li, Jianbao [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 10084 (China); Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Hainan University, Haikou 570228 (China); Lin, Hong [State Key Laboratory of New Ceramics & Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 10084 (China)

    2016-04-30

    Highly transparent and conductive aluminum doped zinc oxide (AZO) films were prepared by sol–gel method on the glass substrates. The effects of doping concentration, annealing temperature and facing direction during annealing on the structural, electrical and optical properties of AZO films were studied by performing a series of characterizations including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis spectrophotometry, four-point probe method and Hall effect measurement system. The results showed that the AZO films were wurtzite crystallized with c-axis preferred orientation. A minimum resistivity of 1.8 × 10{sup −3} Ω cm and a transmittance above 90% were obtained for the film doped with 1.5 at.% aluminum, annealed at 510 °C and faced-down in the oven, which was among the best performance of the currently reported works based on sol–gel process. Moreover, energy level analysis revealed that the AZO film has a work function of 4.3 eV, exhibiting great potential in perovskite solar cell applications. - Highlights: • Highly transparent and conductive AZO films were prepared by sol–gel based process. • Different facing directions during annealing had effects on the carrier mobility. • Less aluminum ions at the grain boundary would favor the carrier transport. • The potential of AZO film in the perovskite solar cell application was discussed.

  11. NaIrO3-A pentavalent post-perovskite

    International Nuclear Information System (INIS)

    Bremholm, M.; Dutton, S.E.; Stephens, P.W.; Cava, R.J.

    2011-01-01

    Sodium iridium (V) oxide, NaIrO 3, was synthesized by a high pressure solid state method and recovered to ambient conditions. It is found to be isostructural with CaIrO 3 , the much-studied structural analog of the high-pressure post-perovskite phase of MgSiO 3 . Among the oxide post-perovskites, NaIrO 3 is the first example with a pentavalent cation. The structure consists of layers of corner- and edge-sharing IrO 6 octahedra separated by layers of NaO 8 bicapped trigonal prisms. NaIrO 3 shows no magnetic ordering and resistivity measurements show non-metallic behavior. The crystal structure, electrical and magnetic properties are discussed and compared to known post-perovskites and pentavalent perovskite metal oxides. -- Graphical abstract: Sodium iridium(V) oxide, NaIrO 3 , synthesized by a high pressure solid state method and recovered to ambient conditions is found to crystallize as the post-perovskite structure and is the first example of a pentavalent ABO 3 post-perovskite. Research highlights: → NaIrO 3 post-perovskite stabilized by pressure. → First example of a pentavalent oxide post-perovskite. → Non-metallic and non-magnetic behavior of NaIrO 3 .

  12. High-pressure stability relations, crystal structures, and physical properties of perovskite and post-perovskite of NaNiF3

    International Nuclear Information System (INIS)

    Shirako, Y.; Shi, Y.G.; Aimi, A.; Mori, D.; Kojitani, H.; Yamaura, K.; Inaguma, Y.; Akaogi, M.

    2012-01-01

    NaNiF 3 perovskite was found to transform to post-perovskite at 16–18 GPa and 1273–1473 K. The equilibrium transition boundary is expressed as P (GPa)=−2.0+0.014×T (K). Structure refinements indicated that NaNiF 3 perovskite and post-perovskite have almost regular NiF 6 octahedra consistent with absence of the first-order Jahn–Teller active ions. Both NaNiF 3 perovskite and post-perovskite are insulators. The perovskite underwent a canted antiferromagnetic transition at 156 K, and the post-perovskite antiferromagnetic transition at 22 K. Magnetic exchange interaction of NaNiF 3 post-perovskite is smaller than that of perovskite, reflecting larger distortion of Ni–F–Ni network and lower dimension of octahedral arrangement in post-perovskite than those in perovskite. - Graphical abstract: Perovskite–post-perovskite transition in NaNiF 3 at high pressure Highlights: ► NaNiF 3 perovskite (Pv) transforms to post-perovskite (pPv) at 16 GPa and 1300 K. ► The equilibrium transition boundary is expressed as P (GPa)=−2.0+0.014 T (K). ► Antiferromagnetic transition occurs at 156 K in Pv and 22 K in pPv.

  13. Antiferroelectric Nature of CH3NH3PbI3-xClx Perovskite and Its Implication for Charge Separation in Perovskite Solar Cells

    Science.gov (United States)

    Sewvandi, Galhenage A.; Kodera, Kei; Ma, Hao; Nakanishi, Shunsuke; Feng, Qi

    2016-07-01

    Perovskite solar cells (PSCs) have been attracted scientific interest due to high performance. Some researchers have suggested anomalous behavior of PSCs to the polarizations due to the ion migration or ferroelectric behavior. Experimental results and theoretical calculations have suggested the possibility of ferroelectricity in organic-inorganic perovskite. However, still no studies have been concretely discarded the ferroelectric nature of perovskite absorbers in PSCs. Hysteresis of P-E (polarization-electric field) loops is an important evidence to confirm the ferroelectricity. In this study, P-E loop measurements, in-depth structural study, analyses of dielectric behavior and the phase transitions of CH3NH3PbI3-xClx perovskite were carried out and investigated. The results suggest that CH3NH3PbI3-xClx perovskite is in an antiferroelectric phase at room temperature. The antiferroelectric phase can be switched to ferroelectric phase by the poling treatment and exhibits ferroelectric-like hysteresis P-E loops and dielectric behavior around room temperature; namely, the perovskite can generate a ferroelectric polarization under PSCs operating conditions. Furthermore, we also discuss the implications of ferroelectric polarization on PSCs charge separation.

  14. Post-perovskite transitions in CaB4+O3 at high pressure

    International Nuclear Information System (INIS)

    Akaogi, M; Shirako, Y; Kojitani, H; Takamori, S; Yamaura, K; Takayama-Muromachi, E

    2010-01-01

    High-pressure phase transitions in CaRhO 3 were examined using a multianvil apparatus up to 27 GPa and 1930 o C. CaRhO 3 perovskite transforms to post-perovskite via a monoclinic intermediate phase with increasing pressure. Volume changes for the transitions of perovskite - intermediate phase and of intermediate phase - post-perovskite are -1.1 and -0.7 %, respectively. CaRhO 3 post-perovskite is the fourth quenchable post-perovskite oxide found so far. By high-temperature calorimetric experiments, enthalpy of the perovskite - post-perovskite transition in CaRuO 3 was measured as 15.2±3.3 kJ/mol. Combining the datum with those of CaIrO 3 , it is shown that CaIrO 3 perovskite is energetically less stable than CaRuO 3 perovskite. This is consistent with the fact that orthorhombic distortion of CaIrO 3 perovskite is larger than CaRuO 3 , as indicated with the tilt-angle of octahedral framework of perovskite structure. The transition pressure from perovskite to post-perovskite in CaBO 3 (B = Ru, Rh, Ir) increases almost linearly with decreasing the tilt-angle, suggesting that the perovskite - post-perovskite transition may result from instability of the perovskite structure with pressure.

  15. Crystal Structure Formation of CH3NH3PbI3-xClx Perovskite

    Directory of Open Access Journals (Sweden)

    Shiqiang Luo

    2016-02-01

    Full Text Available Inorganic-organic hydride perovskites bring the hope for fabricating low-cost and large-scale solar cells. At the beginning of the research, two open questions were raised: the hysteresis effect and the role of chloride. The presence of chloride significantly improves the crystallization and charge transfer property of the perovskite. However, though the long held debate over of the existence of chloride in the perovskite seems to have now come to a conclusion, no prior work has been carried out focusing on the role of chloride on the electronic performance and the crystallization of the perovskite. Furthermore, current reports on the crystal structure of the perovskite are rather confusing. This article analyzes the role of chloride in CH3NH3PbI3-xClx on the crystal orientation and provides a new explanation about the (110-oriented growth of CH3NH3PbI3 and CH3NH3PbI3-xClx.

  16. PbBr3 Perovskite Crystals

    KAUST Repository

    Wei, Tzu-Chiao

    2018-01-31

    Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, the nonlinear optical properties of single crystal inorganic–organic hybrid perovskite CH3NH3PbBr3 are studied. By exciting the material with a 1044 nm laser, strong two-photon absorption-induced photoluminescence in the green spectral region is observed. Using the transmission open-aperture Z-scan technique, the values of the two-photon absorption coefficient are observed to be 8.5 cm GW−1, which is much higher than that of standard two-photon absorbing materials that are industrially used in nonlinear optical applications, such as lithium niobate (LiNbO3), LiTaO3, KTiOPO4, and KH2PO4. Such a strong two-photon absorption effect in CH3NH3PbBr3 can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control the intensity of incident light. In this study, the superior optical limiting, pulse reshaping, and stabilization properties of CH3NH3PbBr3 are demonstrated, opening new applications for perovskites in nonlinear optics.

  17. The efficiency limit of CH3NH3PbI3 perovskite solar cells

    International Nuclear Information System (INIS)

    Sha, Wei E. I.; Ren, Xingang; Chen, Luzhou; Choy, Wallace C. H.

    2015-01-01

    With the consideration of photon recycling effect, the efficiency limit of methylammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite solar cells is predicted by a detailed balance model. To obtain convincing predictions, both AM 1.5 spectrum of Sun and experimentally measured complex refractive index of perovskite material are employed in the detailed balance model. The roles of light trapping and angular restriction in improving the maximal output power of thin-film perovskite solar cells are also clarified. The efficiency limit of perovskite cells (without the angular restriction) is about 31%, which approaches to Shockley-Queisser limit (33%) achievable by gallium arsenide (GaAs) cells. Moreover, the Shockley-Queisser limit could be reached with a 200 nm-thick perovskite solar cell, through integrating a wavelength-dependent angular-restriction design with a textured light-trapping structure. Additionally, the influence of the trap-assisted nonradiative recombination on the device efficiency is investigated. The work is fundamentally important to high-performance perovskite photovoltaics

  18. Perovskite oxide SrTiO3 as an efficient electron transporter for hybrid perovskite solar cells

    KAUST Repository

    Bera, Ashok

    2014-12-11

    In this work, we explored perovskite oxide SrTiO3 (STO) for the first time as the electron-transporting layer in organolead trihalide perovskite solar cells. The steady-state photoluminescence (PL) quenching and transient absorption experiments revealed efficient photoelectron transfer from CH3NH3PbI3-xClx to STO. Perovskite solar cells with meso-STO exhibit an open circuit voltage of 1.01 V, which is 25% higher than the value of 0.81 V achieved in the control device with the conventional meso-TiO2. In addition, an increase of 17% in the fill factor was achieved by tailoring the thickness of the meso-STO layer. We found that the application of STO leads to uniform perovskite layers with large grains and complete surface coverage, leading to a high shunt resistance and improved performance. These findings suggest STO as a competitive candidate as electron transport material in organometal perovskite solar cells.

  19. Perovskite oxide SrTiO3 as an efficient electron transporter for hybrid perovskite solar cells

    KAUST Repository

    Bera, Ashok; Wu, Kewei; Sheikh, Arif D.; Alarousu, Erkki; Mohammed, Omar F.; Wu, Tao

    2014-01-01

    In this work, we explored perovskite oxide SrTiO3 (STO) for the first time as the electron-transporting layer in organolead trihalide perovskite solar cells. The steady-state photoluminescence (PL) quenching and transient absorption experiments revealed efficient photoelectron transfer from CH3NH3PbI3-xClx to STO. Perovskite solar cells with meso-STO exhibit an open circuit voltage of 1.01 V, which is 25% higher than the value of 0.81 V achieved in the control device with the conventional meso-TiO2. In addition, an increase of 17% in the fill factor was achieved by tailoring the thickness of the meso-STO layer. We found that the application of STO leads to uniform perovskite layers with large grains and complete surface coverage, leading to a high shunt resistance and improved performance. These findings suggest STO as a competitive candidate as electron transport material in organometal perovskite solar cells.

  20. High performance photodetector based on 2D CH3NH3PbI3 perovskite nanosheets

    International Nuclear Information System (INIS)

    Li, Pengfei; Shivananju, B N; Li, Shaojuan; Bao, Qiaoliang; Zhang, Yupeng

    2017-01-01

    In this work, a high performance vertical-type photodetector based on two-dimensional (2D) CH 3 NH 3 PbI 3 perovskite nanosheets was fabricated. The low trap density of the perovskite nanosheets and their short carrier diffusion distance result in a significant performance enhancement of the perovskite-based photodetector. The photoresponsivity of this vertical-type photodetector is as high as 36 mA W −1 at visible wavelength, which is much better than traditional perovskite photodetectors (0.34 mA W −1 ). Compared with traditional planar-type perovskite-based photodetectors, this vertical-type photodetector also shows the advantages of low-voltage operation and large responsivity. These results may pave the way for exploiting high performance perovskite-based photodetectors with an ingenious device design. (paper)

  1. Polarized emission from CsPbX3 perovskite quantum dots

    Science.gov (United States)

    Wang, Dan; Wu, Dan; Dong, Di; Chen, Wei; Hao, Junjie; Qin, Jing; Xu, Bing; Wang, Kai; Sun, Xiaowei

    2016-06-01

    Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption.Compared to organic/inorganic hybrid perovskites, full inorganic perovskite quantum dots (QDs) exhibit higher stability. In this study, full inorganic CsPbX3 (X = Br, I and mixed halide systems Br/I) perovskite QDs have been synthesized and interestingly, these QDs showed highly polarized photoluminescence which is systematically studied for the first time. Furthermore, the polarization of CsPbI3 was as high as 0.36 in hexane and 0.40 as a film. The CsPbX3 perovskite QDs with high polarization properties indicate that they possess great potential for application in new generation displays with wide colour gamut and low power consumption. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01915c

  2. Room temperature three-photon pumped CH3NH3PbBr3 perovskite microlasers

    Science.gov (United States)

    Gao, Yisheng; Wang, Shuai; Huang, Can; Yi, Ningbo; Wang, Kaiyang; Xiao, Shumin; Song, Qinghai

    2017-03-01

    Hybrid lead halide perovskites have made great strides in next-generation light-harvesting and light emitting devices. Recently, they have also shown great potentials in nonlinear optical materials. Two-photon absorption and two-photon light emission have been thoroughly studied in past two years. However, the three-photon processes are rarely explored, especially for the laser emissions. Here we synthesized high quality CH3NH3PbBr3 perovskite microstructures with solution processed precipitation method and studied their optical properties. When the microstructures are pumped with intense 1240 nm lasers, we have observed clear optical limit effect and the band-to-band photoluminescence at 540 nm. By increasing the pumping density, whispering-gallery-mode based microlasers have been achieved from CH3NH3PbBr3 perovskite microplate and microrod for the first time. This work demonstrates the potentials of hybrid lead halide perovskites in nonlinear photonic devices.

  3. General working principles of CH3NH3PbX3 perovskite solar cells.

    Science.gov (United States)

    Gonzalez-Pedro, Victoria; Juarez-Perez, Emilio J; Arsyad, Waode-Sukmawati; Barea, Eva M; Fabregat-Santiago, Francisco; Mora-Sero, Ivan; Bisquert, Juan

    2014-02-12

    Organometal halide perovskite-based solar cells have recently realized large conversion efficiency over 15% showing great promise for a new large scale cost-competitive photovoltaic technology. Using impedance spectroscopy measurements we are able to separate the physical parameters of carrier transport and recombination in working devices of the two principal morphologies and compositions of perovskite solar cells, viz. compact thin films of CH3NH3PbI(3-x)Clx and CH3NH3PbI3 infiltrated on nanostructured TiO2. The results show nearly identical spectral characteristics indicating a unique photovoltaic operating mechanism that provides long diffusion lengths (1 μm). Carrier conductivity in both devices is closely matched, so that the most significant differences in performance are attributed to recombination rates. These results highlight the central role of the CH3NH3PbX3 semiconductor absorber in carrier collection and provide a new tool for improved optimization of perovskite solar cells. We report for the first time a measurement of the diffusion length in a nanostructured perovskite solar cell.

  4. Raman spectra of MgSiO3 . 10% Al2O3-perovskite at various pressures and temperatures

    International Nuclear Information System (INIS)

    Liu Lingun; Irifune, T.

    1995-01-01

    Variations of Raman spectra of MgSiO 3 . 10% Al 2 O 3 -perovskite were investigated up to about 270 kbar at room temperature and in the range 108-425 K at atmospheric pressure. Like MgSiO 3 -perovskite, the Raman frequencies of MgSiO 3 . 10% Al 2 O 3 -perovskite increase nonlinearly with increasing pressure and decrease linearly with increasing temperature within the experimental uncertainties and the range investigated. A comparison of these data with those of MgSiO 3 -perovskite suggests that MgSiO 3 . 10% Al 2 O 3 -perovskite is slightly more compressible than MgSiO 3 -perovskite, and that the volume thermal expansion for MgSiO 3 . 10% Al 2 O 3 -perovskite is also slightly greater than that for MgSiO 3 -perovskite. (orig.)

  5. Performance Improvement of CH3NH3PbI3 Perovskite Solar Cell by CH3SH Doping

    Directory of Open Access Journals (Sweden)

    Hong Li

    2016-03-01

    Full Text Available Organometal halide perovskites have recently emerged as an appealing candidate in photovoltaic devices due to their excellent properties. Therefore, intense efforts have been devoted to find the ideal organics for perovskite solar cells. In response, we investigate the doping effect of CH3SH organic on the structure and related performance of a CH3NH3PbI3 perovskite solar cell, via in situ synchrotron- based grazing incidence X-ray diffraction (GIXRD, together with scanning electron microscopy (SEM. In situ GIXRD investigations clearly illustrated the transformation and modification of the perovskite structure induced by the organic dopant, which subsequently led to the enhance‐ ment of the power conversion efficiency of fabricated solar cells. Notably, nanoporous morphology and nanocrystal‐ line structures were discovered in the perovskite film by SEM; they were also confirmed by the increase in broad‐ ening peaks/features in the GIXRD measurements. Overall, our study may ultimately result in an attractive strategy for the fabrication of high performance perovskite solar cells.

  6. O3 perovskite ceramic

    Indian Academy of Sciences (India)

    The prepared sample remains as double phases with the perovskite struc- ture. The structure ... Ferroelectric oxides with perovskite structure are the subject of many investigations. ... in optical devices and heterojunction solar cells. 1765 ...

  7. Formability of ABX3 (X=F,Cl,Br,I) halide perovskites

    International Nuclear Information System (INIS)

    Li Chonghea; Lu Xionggang; Ding Weizhong; Feng Liming; Gao Yonghui; Guo Ziming

    2008-01-01

    In this study a total of 186 complex halide systems were collected; the formabilities of ABX 3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. A model for halide perovskite formability was built up. In this model obtained, for all 186 complex halides systems, only one system (CsF-MnF 2 ) without perovskite structure and six systems (RbF-PbF 2 , CsF- BeF 2 , KCl-FeCl 2 , TlI-MnI 2 , RbI-SnI 2 , TlI-PbI 2 ) with perovskite structure were wrongly classified, so its predicting accuracy reaches 96%. It is also indicated that both the tolerance factor and the octahedral factor are a necessary but not sufficient condition for ABX 3 halide perovskite formability, and a lowest limit of the octahedral factor exists for halide perovskite formation. This result is consistent with our previous report for ABO 3 oxide perovskite, and may be helpful to design novel halide materials with the perovskite structure. (orig.)

  8. Study of transport properties of bodies with a perovskite structure: application to the MgSiO3 perovskite

    International Nuclear Information System (INIS)

    Kapusta, Benedicte

    1990-01-01

    After some recalls on transport in ionic solids (Nernst-Einstein relationship, variation of ionic conductivity, hybrid conduction, fast ionic conduction), this research thesis presents the physical properties of perovskites and more particularly the structure and stability of the MgSiO 3 perovskite: structure and elastic properties, electric conductivity and transport properties in compounds with a perovskite structure. Then, the author reports the experimental study of the KZnF 3 perovskite (a structural analogous of MgSiO 3 ): measurements of electric conductivity under pressure, measurements under atmospheric pressure, result discussion. The next part addresses the numerical simulation of MgSiO 3 : simulation techniques (generalities on molecular dynamics, model description), investigation of structural, elastic and thermodynamic properties, diffusion properties in quadratic phase [fr

  9. Effect of Different CH3NH3PbI3 Morphologies on Photovoltaic Properties of Perovskite Solar Cells

    Science.gov (United States)

    Chen, Lung-Chien; Lee, Kuan-Lin; Wu, Wen-Ti; Hsu, Chien-Feng; Tseng, Zong-Liang; Sun, Xiao Hong; Kao, Yu-Ting

    2018-05-01

    In this study, the perovskite layers were prepared by two-step wet process with different CH3NH3I (MAI) concentrations. The cell structure was glass/FTO/TiO2-mesoporous/CH3NH3PbI3 (MAPbI3)/spiro-OMeTAD/Ag. The MAPbI3 perovskite films were prepared using high and low MAI concentrations in a two-step process. The perovskite films were optimized at different spin coating speed and different annealing temperatures to enhance the power conversion efficiency (PCE) of perovskite solar cells. The PCE of the resulting device based on the different perovskite morphologies was discussed. The PCE of the best cell was up to 17.42%, open circuit voltage of 0.97 V, short current density of 24.06 mA/cm2, and fill factor of 0.747.

  10. Phase formation and UV luminescence of Gd{sup 3+} doped perovskite-type YScO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yuhei; Ueda, Kazushige, E-mail: kueda@che.kyutech.ac.jp

    2016-10-15

    Synthesis of pure and Gd{sup 3+}doped perovskite-type YScO{sub 3} was attempted by a polymerized complex (PC) method and solid state reaction (SSR) method. Crystalline phases and UV luminescence of samples were examined with varying heating temperatures. The perovskite-type single phase was not simply formed in the SSR method, as reported in some literatures, and two cubic C-type phases of starting oxide materials remained forming slightly mixed solid solutions. UV luminescence of Gd{sup 3+} doped samples increased with an increase in heating temperatures and volume of the perovskite-type phase. In contrast, a non-crystalline precursor was crystallized to a single C-type phase at 800 °C in the PC method forming a completely mixed solid solution. Then, the phase of perovskite-type YScO{sub 3} formed at 1200 °C and its single phase was obtained at 1400 °C. It was revealed that high homogeneousness of cations was essential to generate the single perovskite-phase of YScO{sub 3}. Because Gd{sup 3+} ions were also dissolved into the single C-type phase in Gd{sup 3+} doped samples, intense UV luminescence was observed above 800 °C in both C-type phase and perovskite-type phase. - Graphical abstract: A pure perovskite-type YScO{sub 3} phase was successfully synthesized by a polymerized complex (PC) method. The perovskite-type YScO{sub 3} was generated through a solid solution of C-type (Y{sub 0.5}Sc{sub 0.5}){sub 2}O{sub 3} with drastic change of morphology. The PC method enabled a preparation of the single phase of the perovskite-type YScO{sub 3} at lower temperature and in shorter heating time. Gd{sup 3+} doped perovskite-type YScO{sub 3} was found to show a strong sharp UV emission at 314 nm. - Highlights: • Pure YScO{sub 3} phase was successfully synthesized by polymerized complex (PC) method. • Pure perovskite-type YScO{sub 3} phase was generated from pure C-type (Y{sub 0.5}Sc{sub 0.5}){sub 2}O{sub 3} one. • YScO{sub 3} was obtained at lower temperature and

  11. Transparent and flexible photodetectors based on CH3NH3PbI3 perovskite nanoparticles

    Science.gov (United States)

    Jeon, Young Pyo; Woo, Sung Jun; Kim, Tae Whan

    2018-03-01

    Transparent and flexible photodetectors (PDs) based on CH3NH3PbI3 perovskite nanoparticles (NPs) were fabricated by using co-evaporation of methyl ammonium iodide and lead iodide. X-ray diffraction patterns and high-resolution transmission electron microscopy images demonstrated the formation of perovskite NPs. The optical transmittance of the perovskite NPs/glass was above 80% over the entire range of visible wavelengths, indicative of high transparency. The PDs based on CH3NH3PbI3 perovskite NPs were sensitive to a broad range of visible light from 450 to 650 nm. The currents in the PDs under exposure to red, green, and blue light-emitting diodes were enhanced to 5, 10, and 20 times that of the PD in the dark, respectively. The rise and the decay times of the PDs were 50 and 120 μs. The current in the perovskite NP PD on a polyethylene terephthalate substrate was enhanced by approximately 69% when the NP PD was exposed to a blue LED emitting at a wavelength of 459 nm. Despite multiple bending, the transparent and flexible PDs based on methyl ammonium iodide and lead iodide NPs showed reproducibility and high stability in performance.

  12. Effects of Fe-Enrichment on the Equation of State and Stability of (Mg,Fe)SiO3 Perovskite and Post-Perovskite

    Science.gov (United States)

    Dorfman, S. M.; Holl, C. M.; Meng, Y.; Prakapenka, V.; Duffy, T. S.

    2010-12-01

    Fe-enrichment in the deep lower mantle has been proposed as an explanation for seismic anomalies such as large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs). In order to resolve the effect of Fe on the stability and equation of state of the lower mantle’s dominant constituent, (Mg,Fe)SiO3 perovskite, we have studied Fe-rich natural orthopyroxenes, (Mg0.61Fe0.37Ca0.02)SiO3 and (Mg0.25Fe0.70Ca0.05)SiO3 (compositions determined by microprobe analysis), at lower mantle P-T conditions. Pyroxene starting materials were mixed with Au (pressure calibrant and laser absorber) and loaded with NaCl or Ne (pressure medium and thermal insulator) in a symmetric diamond anvil cell. X-ray diffraction experiments at pressures up to 122 GPa with in-situ laser heating were performed at the GSECARS (13-ID-D) and HPCAT (16-ID-B) sectors of the Advanced Photon Source. Heating samples to 2000 K produced single-phase orthorhombic GdFeO3-type perovskite at 63 GPa for the Mg# 61 composition and at 72 GPa for the Mg# 25 composition. At lower pressures (56 GPa for Mg# 61, 67 GPa for Mg# 25), heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression to 93 GPa and higher pressures with laser heating, Mg# 25 perovskite transformed to a two-phase mixture of perovskite and post-perovskite. This is consistent with previous findings that Fe substitution destabilizes (Mg,Fe)SiO3 perovskite relative to (Mg,Fe)SiO3 post-perovskite (Mao et al. 2004, Caracas and Cohen 2005). The bulk modulus at 80 GPa (K80) is ~550 GPa for both Fe-rich perovskites, comparable to values measured for MgSiO3 perovskite (Lundin et al. 2008). However, the volume of Fe-rich perovskites increases linearly with Fe-content. The (Mg0.25Fe0.70Ca0.05)SiO3 perovskite is 3% greater at 80 GPa than V80 for the Mg end

  13. CH3NH3Pb1-xMgxI3 perovskites as environmentally friendly photovoltaic materials

    Science.gov (United States)

    Zhang, Y. D.; Feng, J.

    2018-01-01

    In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1-xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1-xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1-xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1-xMgxI3 (x ≤ 0.25) perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

  14. Fabrication and Characterization of CH3NH3PbI3−x−yBrxCly Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Atsushi Suzuki

    2016-05-01

    Full Text Available Fabrication and characterization of CH3NH3PbI3−x−yBrxCly perovskite solar cells using mesoporous TiO2 as electron transporting layer and 2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino-9,9′-spirobifluorene as a hole-transporting layer (HTL were performed. The purpose of the present study is to investigate role of halogen doping using iodine (I, bromine (Br and chlorine (Cl compounds as dopant on the photovoltaic performance and microstructures of CH3NH3PbI3−x−yBrxCly perovskite solar cells. The X-ray diffraction identified a slight decrease of crystal spacing in the perovskite crystal structure doped with a small amount of I, Br, and Cl in the perovskite compounds. Scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDX showed the perovskite crystal behavior depended on molar ratio of halogen of Pb, I, Br and Cl. Incorporation of the halogen doping into the perovskite crystal structure improved photo generation, carrier diffusion without carrier recombination in the perovskite layer and optimization of electronic structure related with the photovoltaic parameters of open-circuit voltage, short-circuit current density and conversion efficiency. The energy diagram and photovoltaic mechanisms of the perovskite solar cells were discussed in the context of the experimental results.

  15. Optical characterization of voltage-accelerated degradation in CH3NH3PbI3 perovskite solar cells.

    Science.gov (United States)

    Handa, Taketo; Tex, David M; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

    2016-05-16

    We investigate the performance degradation mechanism of CH3NH3PbI3 perovskite solar cells under bias voltage in air and nitrogen atmospheres using photoluminescence and electroluminescence techniques. When applying forward bias, the power conversion efficiency of the solar cells decreased significantly in air, but showed no degradation in nitrogen atmosphere. Time-resolved photoluminescence measurements on these devices revealed that the application of forward bias in air accelerates the generation of non-radiative recombination centers in the perovskite layer buried in the device. We found a negative correlation between the electroluminescence intensity and the injected current intensity in air. The irreversible change of the perovskite grain surface in air initiates the degradation of the perovskite solar cells.

  16. Electron Transfer from Triplet State of TIPS-Pentacene Generated by Singlet Fission Processes to CH3NH3PbI3 Perovskite.

    Science.gov (United States)

    Lee, Sangsu; Hwang, Daesub; Jung, Seok Il; Kim, Dongho

    2017-02-16

    To reveal the applicability of singlet fission processes in perovskite solar cell, we investigated electron transfer from TIPS-pentacene to CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite in film phase. Through the observation of the shorter fluorescence lifetime in TIPS-pentacene/MAPbI 3 perovskite bilayer film (5 ns) compared with pristine MAPbI 3 perovskite film (20 ns), we verified electron-transfer processes between TIPS-pentacene and MAPbI 3 perovskite. Furthermore, the observation of singlet fission processes, a faster decay rate, TIPS-pentacene cations, and the analysis of kinetic profiles of the intensity ratio between 500 and 525 nm in the TA spectra of the TIPS-pentacene/MAPbI 3 perovskite bilayer film indicate that electron transfer occurs from triplet state of TIPS-pentacene generated by singlet fission processes to MAPbI 3 perovskite conduction band. We believe that our results can provide useful information on the design of solar cells sensitized by singlet fission processes and pave the way for new types of perovskite solar cells.

  17. Influence of hydration water on CH3NH3PbI3 perovskite films prepared through one-step procedure.

    Science.gov (United States)

    Wang, Ziyi; Yuan, Sijian; Li, Dahai; Jin, Feng; Zhang, Rongjun; Zhan, Yiqiang; Lu, Ming; Wang, Songyou; Zheng, Yuxiang; Guo, Junpeng; Fan, Zhiyong; Chen, Liangyao

    2016-10-31

    Organic-inorganic perovskites were fabricated through a one-step procedure with different levels of hydration water in precursor solutions. The optical properties of CH3NH3PbI3 films were investigated through spectroscopic ellipsometry and photoluminescence measurements. With the measured optical constants, the efficiency limit of perovskite solar cells is predicted with a detailed balance model. By comparing the optical measurement to that of planar heterojunction solar cells, we conclude that the radiative efficiency and porosity of the perovskite film significantly influence the performance of perovskite solar cells. An optimized hydration-water concentration is obtained for the 3CH3NH3I:1PbAc2•xH2O precursor solution. The results can provide guidance for further optimization of the device performance of perovskite solar cells by utilizing hydration water.

  18. Phase transition in metastable perovskite Pb(AlNb)0,5O3

    International Nuclear Information System (INIS)

    Zhabko, T.E.; Olekhnovich, N.M.; Shilin, A.D.

    1987-01-01

    Dielectric properties of metastable perovskite Pb(AlNb) 0.5 O 3 and X-ray temperature investigations of both perovskite and pyrochlore modifications of the given compound are studied. Samples with the perovskite structure are prepared from the pyrochlorephase at 4-5 GPa pressure and 1170-1270 K. Ferroelectric phase transition is shown to occur in the metastable perovskite phase Pb(AlNb) 0.5 O 3 at 170 K

  19. Electrical Stress Influences the Efficiency of CH3 NH3 PbI3 Perovskite Light Emitting Devices.

    Science.gov (United States)

    Zhao, Lianfeng; Gao, Jia; Lin, YunHui L; Yeh, Yao-Wen; Lee, Kyung Min; Yao, Nan; Loo, Yueh-Lin; Rand, Barry P

    2017-06-01

    Organic-inorganic hybrid perovskite materials are emerging as semiconductors with potential application in optoelectronic devices. In particular, perovskites are very promising for light-emitting devices (LEDs) due to their high color purity, low nonradiative recombination rates, and tunable bandgap. Here, using pure CH 3 NH 3 PbI 3 perovskite LEDs with an external quantum efficiency (EQE) of 5.9% as a platform, it is shown that electrical stress can influence device performance significantly, increasing the EQE from an initial 5.9% to as high as 7.4%. Consistent with the enhanced device performance, both the steady-state photoluminescence (PL) intensity and the time-resolved PL decay lifetime increase after electrical stress, indicating a reduction in nonradiative recombination in the perovskite film. By investigating the temperature-dependent characteristics of the perovskite LEDs and the cross-sectional elemental depth profile, it is proposed that trap reduction and resulting device-performance enhancement is due to local ionic motion of excess ions, likely excess mobile iodide, in the perovskite film that fills vacancies and reduces interstitial defects. On the other hand, it is found that overstressed LEDs show irreversibly degraded device performance, possibly because ions initially on the perovskite lattice are displaced during extended electrical stress and create defects such as vacancies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. CH3NH3Pb1−xMgxI3 perovskites as environmentally friendly photovoltaic materials

    Directory of Open Access Journals (Sweden)

    Y. D. Zhang

    2018-01-01

    Full Text Available In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1−xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1−xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1−xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1−xMgxI3 (x ≤ 0.25 perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

  1. Sn2+—Stabilization in MASnI3 perovskites by superhalide incorporation

    Science.gov (United States)

    Xiang, Junxiang; Wang, Kan; Xiang, Bin; Cui, Xudong

    2018-03-01

    Sn-based hybrid halide perovskites are a potential solution to replace Pb and thereby reduce Pb toxicity in MAPbI3 perovskite-based solar cells. However, the instability of Sn2+ in air atmosphere causes a poor reproducibility of MASnI3, hindering steps towards this goal. In this paper, we propose a new type of organic metal-superhalide perovskite of MASnI2BH4 and MASnI2AlH4. Through first-principles calculations, our results reveal that the incorporation of BH4 and AlH4 superhalides can realize an impressive enhancement of oxidation resistance of Sn2+ in MASnI3 perovskites because of the large electron transfer between Sn2+ and [BH4]-/[AlH4]-. Meanwhile, the high carrier mobility is preserved in these superhalide perovskites and only a slight decrease is observed in the optical absorption strength. Our studies provide a new path to attain highly stable performance and reproducibility of Sn-based perovskite solar cells.

  2. Role of bromine doping on the photovoltaic properties and microstructures of CH3NH3PbI3 perovskite solar cells

    International Nuclear Information System (INIS)

    Suzuki, Atsushi; Okada, Hiroshi; Oku, Takeo

    2016-01-01

    Organic-inorganic hybrid heterojunction solar cells containing CH 3 NH 3 PbI 3 perovskite compound were fabricated using mesoporous TiO 2 as the electronic transporting layer and spirobifluorence as the hole-transporting layer. The purpose of the present study is to investigate role of bromine (Br) doping on the photovoltaic properties and microstructure of CH 3 NH 3 PbI 3 perovskite solar cells. Photovoltaic, optical properties and microstructures of perovskite-based solar cells were investigated. The X-ray diffraction identified crystal structure of the perovskite layer doped with Br in the solar cell. Scanning electron microscopy observation showed a different behavior of surface morphology and the perovskite crystal structure on the TiO 2 mesoporous structure depending on extent amount of hydrogen doping of Br. The role of bromide halogen doping on the perovskite crystal structure and photovoltaic properties was due to improvement of carrier mobility, optimization of electron structure, band gap related with the photovoltaic parameters of V oc , J sc and η. Energy diagram and photovoltaic mechanism of the perovskite solar cells varied with halogen doping was discussed by experimental results

  3. Carrier injection and recombination processes in perovskite CH3NH3PbI3 solar cells studied by electroluminescence spectroscopy

    Science.gov (United States)

    Handa, Taketo; Okano, Makoto; Tex, David M.; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

    2016-02-01

    Organic-inorganic hybrid perovskite materials, CH3NH3PbX3 (X = I and Br), are considered as promising candidates for emerging thin-film photovoltaics. For practical implementation, the degradation mechanism and the carrier dynamics during operation have to be clarified. We investigated the degradation mechanism and the carrier injection and recombination processes in perovskite CH3NH3PbI3 solar cells using photoluminescence (PL) and electroluminescence (EL) imaging spectroscopies. By applying forward bias-voltage, an inhomogeneous distribution of the EL intensity was clearly observed from the CH3NH3PbI3 solar cells. By comparing the PL- and EL-images, we revealed that the spatial inhomogeneity of the EL intensity is a result of the inhomogeneous luminescence efficiency in the perovskite layer. An application of bias-voltage for several tens of minutes in air caused a decrease in the EL intensity and the conversion efficiency of the perovskite solar cells. The degradation mechanism of perovskite solar cells under bias-voltage in air is discussed.

  4. Dendrimer ligands-capped CH3NH3PbBr3 perovskite nanocrystals with delayed halide exchange and record stability against both moisture and water

    Science.gov (United States)

    Xu, Yiren; Xu, Shuhong; Shao, Haibao; Jiang, Han; Cui, Yiping; Wang, Chunlei

    2018-06-01

    CH3NH3PbBr3 perovskite nanocrystals (NCs) suffer from poor stability because of their high sensitivity to environmental moisture and water. To solve this problem, previous works mainly focus on embedding perovskite NCs into water-resistant matrix to form large composites (size of microns or larger). As an alternative solution without serious changing of NC size, enhancing the stability of perovskite NCs themselves by ligand engineering is rarely reported. In this work, we used hyperbranched polyamidoamine (PAMAM) dendrimers with two different generations (G0 and G4) to synthesize CH3NH3PbBr3 perovskite NCs with high photoluminescence (PL) quantum yields (QY) above 70% and a new record stability. A novel dendrimers generation-dependent stability of perovskite NCs was observed. The water-resistance time is 18 h (27 h) for perovskite NCs capped by G0 (G4) generation of PAMAM, which is 7 times (11 times) longer than that of traditional oleic acid-capped NCs. Similar PAMAM generation-related stability is also observed in moisture-resistance tests. The stability time against moisture is 500 h (800 h) for G0 (G4) generation of PAMAM-capped perovskite NCs, which is a new record stability time against moisture for CH3NH3PbBr3 perovskite NCs. In addition, our results also indicate that PAMAM ligands outside perovskite NCs can dramatically slow down the speed of halide exchange. Even for the mixture of perovskite NCs with two different halide composition, the original luminescence properties of PAMAM-capped perovskite NCs can retain after mixing. In view of slow halide exchange speed, excellent water and moisture stability, PAMAM dendrimers-capped perovskite NCs and their mixture are available as color conversion single layer in fabrication of light-emitting diodes (LED).

  5. Dendrimer ligands-capped CH3NH3PbBr3 perovskite nanocrystals with delayed halide exchange and record stability against both moisture and water.

    Science.gov (United States)

    Xu, Yiren; Xu, Shuhong; Shao, Haibao; Jiang, Han; Cui, Yiping; Wang, Chunlei

    2018-06-08

    CH 3 NH 3 PbBr 3 perovskite nanocrystals (NCs) suffer from poor stability because of their high sensitivity to environmental moisture and water. To solve this problem, previous works mainly focus on embedding perovskite NCs into water-resistant matrix to form large composites (size of microns or larger). As an alternative solution without serious changing of NC size, enhancing the stability of perovskite NCs themselves by ligand engineering is rarely reported. In this work, we used hyperbranched polyamidoamine (PAMAM) dendrimers with two different generations (G0 and G4) to synthesize CH 3 NH 3 PbBr 3 perovskite NCs with high photoluminescence (PL) quantum yields (QY) above 70% and a new record stability. A novel dendrimers generation-dependent stability of perovskite NCs was observed. The water-resistance time is 18 h (27 h) for perovskite NCs capped by G0 (G4) generation of PAMAM, which is 7 times (11 times) longer than that of traditional oleic acid-capped NCs. Similar PAMAM generation-related stability is also observed in moisture-resistance tests. The stability time against moisture is 500 h (800 h) for G0 (G4) generation of PAMAM-capped perovskite NCs, which is a new record stability time against moisture for CH 3 NH 3 PbBr 3 perovskite NCs. In addition, our results also indicate that PAMAM ligands outside perovskite NCs can dramatically slow down the speed of halide exchange. Even for the mixture of perovskite NCs with two different halide composition, the original luminescence properties of PAMAM-capped perovskite NCs can retain after mixing. In view of slow halide exchange speed, excellent water and moisture stability, PAMAM dendrimers-capped perovskite NCs and their mixture are available as color conversion single layer in fabrication of light-emitting diodes (LED).

  6. The electronic and optical properties of CH3NH3MoI3 perovskite

    Science.gov (United States)

    Kansara, Shivam; Sonvane, Yogesh; Gupta, Sanjeev K.

    2018-05-01

    In this work, a first-principles theoretical study of hybrid perovskite CH3NH3MoI3 is performed using PBE exchange-correlation approximations in density functional theory. The results of electronic band structure are 0.90 eV (M-point: Direct) and 0.60 eV (R-X point: Indirect), respectively. We have also calculated the dielectric properties such as real, imaginary, extension coefficient (K) and reflectivity (R) properties of hybrid perovskite CH3NH3MoI3. The low-bandgap molecules are used to absorb near-IR range and typically having a bandgap smaller than 1.6 eV. This is particularly attractive in organic photovoltaics (OPV), photodetectors (PDs), and ambipolar field-effect transistors (FETs).

  7. Enhancement of photoresponse property of perovskite solar cell by aluminium chloride (AlCl3)

    Science.gov (United States)

    Ghosh, S. S.; Sil, A.

    2018-05-01

    The fabrication of a three layer solar cell device is a new area of research. The formation of perovskite phase is evident from x-ray diffraction and its particle size is observed by microstructural analysis. A thin layer of gold coating over the device increases the surface conductivity. Direct contact between a SnCl2 or AlCl3 based perovskite with the gold coating increases the durability of the film but decreases the hole transport properties due to absence of an organic hole transport material. The absorbance spectroscopy analysis gives characteristic peaks showing the evidence of ITO, TiO2 (rutile) and Sn2+ complexes present in the Sn-perovskite film or Al3+ complexes present within the Al-perovskite cell. The desired absorbance near 550 nm due to Al3+ complexes causes a much higher flow of current on illumination and thus is also evidenced by the presence of comparatively high intensity PL spectra in the Al-perovskite system which occurred due to free exciton formation near band edge excitation. The fill factor of the devices is estimated as ∼0.83 and ∼0.65 for Sn-perovskite and Al-perovskite devices respectively. The PCE values of Sn-perovskite and Al-perovskite devices are calculated 0.39% and 0.96% respectively, which establish Al-perovskite film as a useful component for future solar cell device manufacturing.

  8. Synthesis and characterization of a-site doped LaTiO3 nano perovskites

    International Nuclear Information System (INIS)

    Bradha, M.; Ashok, Anuradha

    2013-01-01

    Nano-sized lanthanum titanate perovskites (La (1-x) A x TiO 3 ) (A= Ba, Sr, Ca) were prepared by sol-gel method and calcined at 800℃. The synthesised perovskites were characterized by Thermogravimetry/ Differential thermal analysis (TGA/DTA), X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM) etc. LaTiO 3 is a perovskite having prominent interest for a variety of applications such as dielectric, insulators, charge-transport properties etc. It is a defect perovskite, with transport properties varying from insulating to metallic based on oxygen stoichiometry. In a quest to observe the effect of the nano size on its properties, lanthanum titanate (LaTiO 3 ) nano perovskites with different dopants on the A-site were prepared by using sol-gel method. In the present work we discuss the synthesis and structural analysis of (La 0.8 A 0.2 TiO 3 ). Phase purity and structural analysis of the calcined samples were performed by powder X-ray diffraction (XRD, with CuKα radiation). In addition to this, morphology and crystal structure was examined by Transmission Electron Microscopy (TEM) using a JEOL JEM 2100 HRTEM. HRTEM studies indicate that the nano perovskites are of size around 20 nm. Ring pattern in SAED also confirms that the perovskite is polycrystalline/nanocrystalline. More detailed study on high resolution images and crystal structure shed light on the reason for the properties exhibited by this perovskites

  9. Pressure-Induced Metallization of the Halide Perovskite (CH 3 NH 3 )PbI 3

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, Adam; Lin, Yu [Photon; Mao, Wendy L. [Photon; Karunadasa, Hemamala I.

    2017-03-10

    We report the metallization of the hybrid perovskite semiconductor (MA)PbI3 (MA = CH3NH3+) with no apparent structural transition. We tracked its bandgap evolution during compression in diamond-anvil cells using absorption spectroscopy and observed strong absorption over both visible and IR wavelengths at pressures above ca. 56 GPa, suggesting the imminent closure of its optical bandgap. The metallic character of (MA)PbI3 above 60 GPa was confirmed using both IR reflectivity and variable-temperature dc conductivity measurements. The impressive semiconductor properties of halide perovskites have recently been exploited in a multitude of optoelectronic applications. Meanwhile, the study of metallic properties in oxide perovskites has revealed diverse electronic phenomena. Importantly, the mild synthetic routes to halide perovskites and the templating effects of the organic cations allow for fine structural control of the inorganic lattice. Pressure-induced closure of the 1.6 eV bandgap in (MA)PbI3 demonstrates the promise of the continued study of halide perovskites under a range of thermodynamic conditions, toward realizing wholly new electronic properties.

  10. CH3 NH3 PbBr3 Perovskite Nanocrystals as Efficient Light-Harvesting Antenna for Fluorescence Resonance Energy Transfer.

    Science.gov (United States)

    Muthu, Chinnadurai; Vijayan, Anuja; Nair, Vijayakumar C

    2017-05-04

    Hybrid perovskites have created enormous research interest as a low-cost material for high-performance photovoltaic devices, light-emitting diodes, photodetectors, memory devices and sensors. Perovskite materials in nanocrystal form that display intense luminescence due to the quantum confinement effect were found to be particularly suitable for most of these applications. However, the potential use of perovskite nanocrystals as a light-harvesting antenna for possible applications in artificial photosynthesis systems is not yet explored. In the present work, we study the light-harvesting antenna properties of luminescent methylammonium lead bromide (CH 3 NH 3 PbBr 3 )-based perovskite nanocrystals using fluorescent dyes (rhodamine B, rhodamine 101, and nile red) as energy acceptors. Our studies revealed that CH 3 NH 3 PbBr 3 nanocrystals are an excellent light-harvesting antenna, and efficient fluorescence resonance energy transfer occurs from the nanocrystals to fluorescent dyes. Further, the energy transfer efficiency is found to be highly dependent on the number of anchoring groups and binding ability of the dyes to the surface of the nanocrystals. These observations may have significant implications for perovskite-based light-harvesting devices and their possible use in artificial photosynthesis systems. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effects of GeI2 or ZnI2 addition to perovskite CH3NH3PbI3 photovoltaic devices

    Science.gov (United States)

    Tanaka, Hiroki; Ohishi, Yuya; Oku, Takeo

    2018-01-01

    CH3NH3PbI3 added with GeI2 or ZnI2 perovskite photovoltaic devices were fabricated characterized. The surface coverages of the perovskite layers were improved by the addition of GeI2 or ZnI2. Formation of PbI2 observed for the pristine CH3NH3PbI3 was suppressed by the GeI2 or ZnI2 addition, which resulted in the improvement of the conversion efficiencies of the perovskite photovoltaic devices.

  12. Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

    KAUST Repository

    Dang, Yangyang; Zhong, Cheng; Zhang, Guodong; Ju, Dianxing; Wang, Lei; Xia, Shengqing; Xia, Haibing; Tao, Xutang

    2016-01-01

    substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites

  13. Single-crystal perovskite CH3NH3PbBr3 prepared by cast capping method for light-emitting diodes

    Science.gov (United States)

    Nguyen, Van-Cao; Katsuki, Hiroyuki; Sasaki, Fumio; Yanagi, Hisao

    2018-04-01

    In this study, electroluminescence from single crystals of CH3NH3PbBr3 perovskite is explored. The cast capping method was applied to fabricate simple devices with an ITO/CH3NH3PbBr3/ITO structure. The devices showed a low operation voltage of 2 V and a pure green luminescence with full width at half maximum of ∼20 nm. However, the emission occurring at the crystal edges demonstrated blinking with a subsecond time interval, which is similar to the previously reported photoluminescence behavior of nanocrystal perovskites. This electroluminescence blinking may provide new insight into the recombination processes depending on the carrier traps and defects of emission layers in perovskite light-emitting devices.

  14. Role of bromine doping on the photovoltaic properties and microstructures of CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Okada, Hiroshi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga, 522-8533 (Japan)

    2016-02-01

    Organic-inorganic hybrid heterojunction solar cells containing CH{sub 3}NH{sub 3}PbI{sub 3} perovskite compound were fabricated using mesoporous TiO{sub 2} as the electronic transporting layer and spirobifluorence as the hole-transporting layer. The purpose of the present study is to investigate role of bromine (Br) doping on the photovoltaic properties and microstructure of CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cells. Photovoltaic, optical properties and microstructures of perovskite-based solar cells were investigated. The X-ray diffraction identified crystal structure of the perovskite layer doped with Br in the solar cell. Scanning electron microscopy observation showed a different behavior of surface morphology and the perovskite crystal structure on the TiO{sub 2} mesoporous structure depending on extent amount of hydrogen doping of Br. The role of bromide halogen doping on the perovskite crystal structure and photovoltaic properties was due to improvement of carrier mobility, optimization of electron structure, band gap related with the photovoltaic parameters of V{sub oc}, J{sub sc} and η. Energy diagram and photovoltaic mechanism of the perovskite solar cells varied with halogen doping was discussed by experimental results.

  15. Annealing Effect on (FAPbI31−x(MAPbBr3x Perovskite Films in Inverted-Type Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2016-09-01

    Full Text Available This study determines the effects of annealing treatment on the structure and the optical and electronic behaviors of the mixed (FAPbI31−x(MAPbBr3x perovskite system. The experimental results reveal that (FAPbI31−x(MAPbBr3x (x ~ 0.2 is an effective light-absorbing material for use in inverted planar perovskite solar cells owing to its large absorbance and tunable band gap. Therefore, good band-matching between the (FAPbI31−x(MAPbBr3x and C60 in photovoltaic devices can be controlled by annealing at various temperatures. Accordingly, an inverted mixed perovskite solar cell with a record efficiency of 12.0% under AM1.5G irradiation is realized.

  16. Oxygen storage capacity and structural properties of Ni-doped LaMnO3 perovskites

    International Nuclear Information System (INIS)

    Ran, Rui; Wu, Xiaodong; Weng, Duan; Fan, Jun

    2013-01-01

    Graphical abstract: Dynamic OSC of (a) fresh and (b) aged LaMn 1−x Ni x O 3 perovskites (0.1 Hz). Aged condition: 1050 °C, 5 h, 7% steam in air. The LaMn 1−x Ni x O 3 perovskites exhibit considerable dynamic OSC in comparison to CeO 2 –ZrO 2 (CZ), even after 1050 °C hydrothermal ageing for 5 h. Highlights: •Ni-doped LaMnO 3 perovskites exhibit very large dynamic OSC and high oxygen storage rate. •Mn 4+ is favourable to the releasable oxygen. •Doping of Ni ions increase the Mn 4+ content and the oxygen vacancies. •Doping of Ni ions reduce the BO 6 distortion in the LaMnO 3 perovskites. -- Abstract: A series of Ni doped LaMnO 3 perovskites were prepared by a sol–gel method as oxygen storage materials. Powder X-ray diffraction (XRD), X-ray adsorption fine structure (XAFS), oxygen storage capacity (OSC) and H 2 -temperature program reduction (TPR) measurements were performed to investigate the OSC of the perovskites as well as the effects of Ni on the structural properties. The results showed that the Ni-doped LaMnO 3 perovskite exhibited very large dynamic OSC and high oxygen release rate, which provided a possibility to serve as an oxygen storage material candidate in three-way catalysts. The available oxygen species below 500 °C primarily originated from the redox reaction between Mn 4+ and Mn 3+ , and the more Mn 4+ were favourable to the releasable oxygen. The doping of appropriate Ni ions promoted the OSC of the LaMnO 3 perovskites by increasing the Mn 4+ content and adjusting the structural defects. On the other hand, the doped Ni ions could make the BO 6 distortion disappearing in the LaMnO 3 perovskites to reduce the lattice oxygen activity

  17. Using Low Temperature Photoluminescence Spectroscopy to Investigate CH3NH3PbI3 Hybrid Perovskite Degradation

    Directory of Open Access Journals (Sweden)

    Khaoula Jemli

    2016-07-01

    Full Text Available Investigating the stability and evaluating the quality of the CH3NH3PbI3 perovskite structures is quite critical both to the design and fabrication of high-performance perovskite devices and to fundamental studies of the photophysics of the excitons. In particular, it is known that, under ambient conditions, CH3NH3PbI3 degrades producing some PbI2. We show here that low temperature Photoluminescence (PL spectroscopy is a powerful tool to detect PbI2 traces in hybrid perovskite layers and single crystals. Because PL spectroscopy is a signal detection method on a black background, small PbI2 traces can be detected, when other methods currently used at room temperature fail. Our study highlights the extremely high stability of the single crystals compared to the thin layers and defects and grain boundaries are thought to play an important role in the degradation mechanism.

  18. Efficiency enhancement of perovskite solar cells using structural and morphological improvement of CH3NH3PbI3 absorber layers

    Science.gov (United States)

    Alidaei, Maryam; Izadifard, Morteza; Ghazi, Mohammad E.; Ahmadi, Vahid

    2018-01-01

    Perovskite solar cells have been heavily investigated due to their unique properties such as high power conversion efficiency (PCE), low-cost fabrication by solution processes, high diffusion length, large absorption coefficient, and direct and tunable band gap. PCE of perovskite devices is strongly dependent on the absorber layer properties such as morphology, crystallinity, and compactness, which are required to be optimized. In this work, the CH3NH3PbI3 (170-480 nm) absorber layers with various methylammonium iodine (MAI) concentrations (7, 10, 20 and 40 mg ml-1) and perovskite solar cells with the fluorine-doped tin oxide (400 nm)/C-TiO2 (30 nm)/Meso-TiO2 (400 nm)/CH3NH3PbI3 (170-480 nm)/P3HT (30 nm)/Au (100 nm) structure were fabricated. A two-step solution process was used for deposition of the CH3NH3PbI3 absorber layers. The morphology, crystal structure, and optical properties of the perovskite layer grown on glass and also the photovoltaic properties of the fabricated solar cells were studied. The results obtained showed that by controlling the deposition conditions, due to the reduction in charge recombination, PCE enhancement of the perovskite solar cell (up to 11.6%) was accessible.

  19. Anomalous perovskite PbRuO3 stabilized under high pressure

    Science.gov (United States)

    Cheng, J.-G.; Kweon, K. E.; Zhou, J.-S.; Alonso, J. A.; Kong, P.-P.; Liu, Y.; Jin, Changqing; Wu, Junjie; Lin, Jung-Fu; Larregola, S. A.; Yang, Wenge; Shen, Guoyin; MacDonald, A. H.; Manthiram, Arumugam; Hwang, G. S.; Goodenough, John B.

    2013-01-01

    Perovskite oxides ABO3 are important materials used as components in electronic devices. The highly compact crystal structure consists of a framework of corner-shared BO6 octahedra enclosing the A-site cations. Because of these structural features, forming a strong bond between A and B cations is highly unlikely and has not been reported in the literature. Here we report a pressure-induced first-order transition in PbRuO3 from a common orthorhombic phase (Pbnm) to an orthorhombic phase (Pbn21) at 32 GPa by using synchrotron X-ray diffraction. This transition has been further verified with resistivity measurements and Raman spectra under high pressure. In contrast to most well-studied perovskites under high pressure, the Pbn21 phase of PbRuO3 stabilized at high pressure is a polar perovskite. More interestingly, the Pbn21 phase has the most distorted octahedra and a shortest Pb—Ru bond length relative to the average Pb—Ru bond length that has ever been reported in a perovskite structure. We have also simulated the behavior of the PbRuO3 perovskite under high pressure by first principles calculations. The calculated critical pressure for the phase transition and evolution of lattice parameters under pressure match the experimental results quantitatively. Our calculations also reveal that the hybridization between a Ru:t2g orbital and an sp hybrid on Pb increases dramatically in the Pbnm phase under pressure. This pressure-induced change destabilizes the Pbnm phase to give a phase transition to the Pbn21 phase where electrons in the overlapping orbitals form bonding and antibonding states along the shortest Ru—Pb direction at P > Pc. PMID:24277807

  20. Perovskites in the comb roof base of hornets: their possible function.

    Science.gov (United States)

    Ishay, J S; Joseph, Z; Galushko, D; Ermakov, N; Bergman, D J; Barkay, Z; Stokroos, I; van der Want, J

    2005-04-01

    On the ceiling of the Oriental hornet comb cell, there are mineral granules of polycrystalline material known to belong to the group of perovskites. In a comb cell intended to house a worker hornet, the roof base usually carries one or several such perovskite granules containing titanium (Ti), whereas in the roof base of a cell housing a developing queen, there are usually several granules containing a high percentage of silicon (Si), aluminum (Al), calcium (Ca), and iron (Fe), but very little if any Ti. In worker comb cells, Ti usually appears as ilmenite (FeTiO3). Besides documenting the above-mentioned facts, this report discusses possible reasons for the appearance of ilmenite crystals in worker cells only and not in queen cells. (c) 2005 Wiley-Liss, Inc.

  1. Electrochemical reduction of nitrous oxide on La1-xSrxFeO3 perovskites

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent

    2010-01-01

    The electrochemical reduction of nitrous oxide and oxygen has been studied on cone-shaped electrodes of La1-xSrxFeO3-delta perovskites in an all solid state cell, using cyclic voltammetry. It was shown that the activity of the La1-xSrxFeO3-delta perovskites for the electrochemical reduction...... of nitrous oxide mainly depends on the amount of Fe(III) and oxide ion vacancies. The activity of the La1-xSrxFeO3-delta perovskites towards the electrochemical reduction of nitrous oxide is much lower than the activity of the La1-xSrxFeO3-delta perovskites towards the electrochemical reduction of oxygen...

  2. Evolution of Photoluminescence, Raman, and Structure of CH3NH3PbI3 Perovskite Microwires Under Humidity Exposure

    Science.gov (United States)

    Segovia, Rubén; Qu, Geyang; Peng, Miao; Sun, Xiudong; Shi, Hongyan; Gao, Bo

    2018-03-01

    Self-assembled organic-inorganic CH3NH3PbI3 perovskite microwires (MWs) upon humidity exposure along several weeks were investigated by photoluminescence (PL) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). We show that, in addition to the common perovskite decomposition into PbI2 and the formation of a hydrated phase, humidity induced a gradual PL redshift at the initial weeks that is stabilized for longer exposure ( 21 nm over the degradation process) and an intensity enhancement. Original perovskite Raman band and XRD reflections slightly shifted upon humidity, indicating defects formation and structure distortion of the MWs crystal lattice. By correlating the PL, Raman, and XRD results, it is believed that the redshift of the MWs PL emission was originated from the structural disorder caused by the incorporation of H2O molecules in the crystal lattice and radiative recombination through moisture-induced subgap trap states. Our study provides insights into the optical and structural response of organic-inorganic perovskite materials upon humidity exposure.

  3. Composition-dependent emission linewidth broadening in lead bromide perovskite (APbBr3, A = Cs and CH3NH3) nanoparticles.

    Science.gov (United States)

    Ham, Sujin; Chung, Heejae; Kim, Tae-Woo; Kim, Jiwon; Kim, Dongho

    2018-02-01

    Lead halide perovskite nanoparticles (NPs) are attractive as they exhibit excellent color purity and have a tunable band gap, and can thus be applied in highly efficient photovoltaic and light-emitting diodes. Fundamental studies of emission linewidth broadening due to spectral shifts in perovskite NPs may suggest a way to improve their color purity. However, the carrier-induced Stark shift that causes spectral diffusion still requires investigation. In this study, we explore composition-related emission linewidth broadening by comparing CsPbBr3 and CH 3 NH 3 PbBr 3 (MAPbBr3) perovskite NPs. We find that the MAPbBr3 NPs are more sensitive to fluctuations in the local electric fields than the CsPbBr3 NPs due to an intrinsic difference in the dipole moment between the two A cations (Cs and MA), which shows a carrier-induced Stark shift. The results indicate that the compositions of perovskite NPs are closely associated with emission linewidth broadening and they also provide insights into the development of NP-based devices with high color purity.

  4. Perovskite structures in the formation of nano-rods in REBa2Cu3O7-δ films self-organization to perovskite structures

    International Nuclear Information System (INIS)

    Mukaida, Masashi; Kai, Hideki; Shingai, Yuki

    2009-01-01

    Cubic perovskite structure has been found to play an important role for the nano-rod formation in REBa 2 Cu 3 O 7-δ films. BaWO 4 , with a sheelite structure, and BaNb 2 O 6 , with a tungsten bronze structure, were doped into REBa 2 Cu 3 O 7-δ targets. Laser-deposited, these materials form nano-rods in REBa 2 Cu 3 O 7-δ films accompanied by Ln elements, resulting in the composition of a pseudo-cubic perovskite structure. This was confirmed by selected area electron diffraction patterns (SADP) and composition mapping using energy-dispersive X-ray spectroscopy scanning transmission electron microscope (EDS-STEM) analysis. BaWO 4 with a sheelite structure, and BaNb 2 O 6 with a tungsten bronze structure, doped into targets no longer retain their structures, but can form pseudo-cubic perovskite structures in laser-deposited REBa 2 Cu 3 O 7-δ films. The perovskite crystal structure is thought to be important for nano-rod formation in the laser deposited REBa 2 Cu 3 O 7-δ film. (author)

  5. Efficient CH3NH3PbI3 perovskite/fullerene planar heterojunction hybrid solar cells with oxidized Ni/Au/Cu transparent electrode

    Science.gov (United States)

    Lai, Wei-Chih; Lin, Kun-Wei; Guo, Tzung-Fang; Chen, Peter; Liao, Yuan-Yu

    2018-02-01

    We demonstrated the performance of inverted CH3NH3PbI3 perovskite-based solar cells (SCs) with a thermally oxidized nickel/gold/copper (Ni/Au/Cu) trilayer transparent electrode. Oxidized Ni/Au/Cu is a high transparent layer and has less resistance than the oxidized Ni/Au layer. Like the oxidized Ni/Au layer, oxidized Ni and Cu in oxidized Ni/Au/Cu could perform as a hole transport layer of the perovskite-based SCs. It leads to improved perovskite SC performance on an open circuit voltage of 1.01 V, a short circuit current density of 14.36 mA/cm2, a fill factor of 76.7%, and a power conversion efficiency (η%) of 11.1%. The η% of perovskite SCs with oxidized Ni (10 nm)/Au (6 nm)/Cu (1 nm) improved by approximately 10% compared with that of perovskite SCs with oxidized Ni/Au.

  6. Reversible modulation of CsPbBr3 perovskite nanocrystal/gold nanoparticle heterostructures.

    Science.gov (United States)

    Chen, Shanshan; Lyu, Danya; Ling, Tao; Guo, Weiwei

    2018-04-19

    A facile strategy is illustrated to reversibly modulate CsPbBr3 perovskite nanocrystal/Au nanoparticle heterostructures with the reversible formation and fragmentation of gold nanoparticles anchored to the corners and surface of CsPbBr3 perovskite nanocrystals. The modulation process was performed under ambient conditions and could be conducted for cycles.

  7. High-Performance CH3NH3PbI3-Inverted Planar Perovskite Solar Cells with Fill Factor Over 83% via Excess Organic/Inorganic Halide.

    Science.gov (United States)

    Jahandar, Muhammad; Khan, Nasir; Lee, Hang Ken; Lee, Sang Kyu; Shin, Won Suk; Lee, Jong-Cheol; Song, Chang Eun; Moon, Sang-Jin

    2017-10-18

    The reduction of charge carrier recombination and intrinsic defect density in organic-inorganic halide perovskite absorber materials is a prerequisite to achieving high-performance perovskite solar cells with good efficiency and stability. Here, we fabricated inverted planar perovskite solar cells by incorporation of a small amount of excess organic/inorganic halide (methylammonium iodide (CH 3 NH 3 I; MAI), formamidinium iodide (CH(NH 2 ) 2 I; FAI), and cesium iodide (CsI)) in CH 3 NH 3 PbI 3 perovskite film. Larger crystalline grains and enhanced crystallinity in CH 3 NH 3 PbI 3 perovskite films with excess organic/inorganic halide reduce the charge carrier recombination and defect density, leading to enhanced device efficiency (MAI+: 14.49 ± 0.30%, FAI+: 16.22 ± 0.38% and CsI+: 17.52 ± 0.56%) compared to the efficiency of a control MAPbI 3 device (MAI: 12.63 ± 0.64%) and device stability. Especially, the incorporation of a small amount of excess CsI in MAPbI 3 perovskite film leads to a highly reproducible fill factor of over 83%, increased open-circuit voltage (from 0.946 to 1.042 V), and short-circuit current density (from 18.43 to 20.89 mA/cm 2 ).

  8. Interplay between organic cations and inorganic framework and incommensurability in hybrid lead-halide perovskite CH3NH3PbBr3

    Science.gov (United States)

    Guo, Yinsheng; Yaffe, Omer; Paley, Daniel W.; Beecher, Alexander N.; Hull, Trevor D.; Szpak, Guilherme; Owen, Jonathan S.; Brus, Louis E.; Pimenta, Marcos A.

    2017-09-01

    Organic-inorganic coupling in the hybrid lead-halide perovskite is a central issue in rationalizing the outstanding photovoltaic performance of these emerging materials. Here, we compare and contrast the evolution of the structure and dynamics of hybrid CH3NH3PbBr3 and inorganic CsPbBr3 lead-halide perovskites with temperature, using Raman spectroscopy and single-crystal x-ray diffraction. Results reveal a stark contrast between their order-disorder transitions, which are abrupt for the hybrid whereas smooth for the inorganic perovskite. X-ray diffraction observes an intermediate incommensurate phase between the ordered and the disordered phases in CH3NH3PbBr3 . Low-frequency Raman scattering captures the appearance of a sharp soft mode in the incommensurate phase, ascribed to the theoretically predicted amplitudon mode. Our work highlights the interaction between the structural dynamics of organic cation CH3NH3+ and the lead-halide framework, and unravels the competition between tendencies for the organic and inorganic moieties to minimize energy in the incommensurate phase of the hybrid perovskite structure.

  9. Conductivity of CH{sub 3}NH{sub 3}PbI{sub 3} thin film perovskite stored in ambient atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Gebremichael, Bizuneh, E-mail: bizunehme@gmail.com [Physics Department, Addis Ababa University, Addis Ababa, P.O. Box 1176 (Ethiopia); Alemu, Getachew [Physics Department, Addis Ababa University, Addis Ababa, P.O. Box 1176 (Ethiopia); Tessema Mola, Genene [School of Chemistry & Physics, University of KwaZulu-Nat al, Pietermaritzburg Campus, Private Bag X01, Scottsville 3209 (South Africa)

    2017-06-01

    Time dependent conductivity loss in CH{sub 3}NH{sub 3}PbI{sub 3} thin film perovskite stored in ambient atmosphere were studied based on electrical and optical measurements. Recent investigations on thin film perovskite solar cell suggest that in the steady state operation of the device, the V{sub oc} is unchanged by continuous illumination of light. Rather the reduction in the power conversion efficiency is caused by significant reduction of the short circuit current (J{sub sc}). In this paper, the effect of light on the optical absorption and electrical conductivity of the CH{sub 3}NH{sub 3}PbI{sub 3} thin film which is deposited on a glass substrate is investigated. The temperature dependent conductivity measurements indicated that the dominant conduction mechanism in the film perovskite is electronic rather than ionic.

  10. Engineering of CH 3 NH 3 PbI 3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties

    KAUST Repository

    Peng, Wei

    2016-07-28

    The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite\\'s three-dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.

  11. Ba2+ Doped CH3NH3PbI3 to Tune the Energy State and Improve the Performance of Perovskite Solar Cells

    International Nuclear Information System (INIS)

    Zhang, Hanbing; Shang, Ming-hui; Zheng, Xiaoying; Zeng, Zhaobing; Chen, Renjie; Zhang, Ying; Zhang, Jing; Zhu, Yuejin

    2017-01-01

    Highlights: •Ba doping enlarges the energy band gap of MAPb 1-x Ba x I 3 . •Voc and Jsc are enhanced in perovskite solar cells. •DFT calculation proves the experiment results. -- Abstract: Elements substitution and doping in perovskite CH 3 NH 3 PbI 3 exhibit versatile tunability of energy band structure and opto-electric properties. Ba 2+ is chosen to substitute Pb 2+ for its similar valence state and ionic radius with Pb 2+ . Ba 2+ doping in perovskite (mol% <5) slightly enlarges the optic energy gap by conduction band minimum(CBM) upshifting to vacuum energy level, which is due to the smaller electronegativity of Ba than Pb. The enlarged band gap is also verified by density function theory calculations. In n-i-p structure perovskite solar cells (PSCs), because of the higher CBM of doped perovskite, the Fermi energy difference between n and p side is enlarged and the electron injection from the perovskite to TiO 2 is improved. Thus, both the photovoltage and photocurrent are improved by small amount Ba 2+ doping, resulting optimized 17.4% efficiency under AM1.5. This work reveals the relationship between the doping element property and the energy band structure of the perovskite, and highlights the doping method to improve the performance of PSCs.

  12. Improving the Morphology of the Perovskite Absorber Layer in Hybrid Organic/Inorganic Halide Perovskite MAPbI3 Solar Cells

    Directory of Open Access Journals (Sweden)

    I. J. Ogundana

    2017-01-01

    Full Text Available Recently, perovskite solar cells have attracted tremendous attention due to their excellent power conversion efficiency, low cost, simple fabrications, and high photovoltaic performance. Furthermore, the perovskite solar cells are lightweight and possess thin film and semitransparency. However, the nonuniformity in perovskite layer constitutes a major setback to the operation mechanism, performance, reproducibility, and degradation of perovskite solar cells. Therefore, one of the main challenges in planar perovskite devices is the fabrication of high quality films with controlled morphology and least amount of pin-holes for high performance thin film perovskite devices. The poor reproducibility in perovskite solar cells hinders the accurate fabrication of practical devices for use in real world applications, and this is primarily as a result of the inability to control the morphology of perovskites, leading to large variability in the characteristics of perovskite solar cells. Hence, the focus of research in perovskites has been mostly geared towards improving the morphology and crystallization of perovskite absorber by selecting the optimal annealing condition considering the effect of humidity. Here we report a controlled ambient condition that is necessary to grow uniform perovskite crystals. A best PCE of 7.5% was achieved along with a short-circuit current density of 15.2 mA/cm2, an open-circuit voltage of 0.81 V, and a fill factor of 0.612 from the perovskite solar cell prepared under 60% relative humidity.

  13. Crystal growth and characterization of Tm doped mixed rare-earth aluminum perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Totsuka, Daisuke, E-mail: totsuka@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho, Tatebayashi, Gunma 374-0047 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Sugiyama, Makoto; Fujimoto, Yutaka; Yokota, Yuui [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystals were grown by the {mu}-PD method. Black-Right-Pointing-Pointer The grown crystals were single phase with perovskite structure (Pbnm). Significant segregation of Lu and Gd was detected in the growth direction. Black-Right-Pointing-Pointer Some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited. Black-Right-Pointing-Pointer Radioluminescence spectra showed several emission peaks ascribed to Tm{sup 3+} and Gd{sup 3+}. -- Abstract: In this work, we present results of structural characterization and optical properties including radio luminescence of (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystal scintillators for (x, y) = (0.30, 0.19), (0, 0.19) and (0, 0) grown by the micro-pulling-down ({mu}-PD) method. The grown crystals were single phase materials with perovskite structure (Pbnm) as confirmed by XRD and had a good crystallinity. The distribution of the crystal constituents in growth direction was evaluated, and significant segregation of Lu and Gd was detected in (Lu{sub 0.30}Gd{sub 0.19}Y{sub 0.50}Tm{sub 0.01})AP sample. The crystals demonstrated 70% transmittance in visible wavelength range and some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited in 190-900 nm. The radioluminescence measurement under X-ray irradiation demonstrated several emission peaks ascribed to 4f-4f transitions of Tm{sup 3+} and Gd{sup 3+}. The ratio of emission intensity in longer wavelength range was increased when Y was replaced by Lu or Gd.

  14. One-Year stable perovskite solar cells by 2D/3D interface engineering

    Science.gov (United States)

    Grancini, G.; Roldán-Carmona, C.; Zimmermann, I.; Mosconi, E.; Lee, X.; Martineau, D.; Narbey, S.; Oswald, F.; de Angelis, F.; Graetzel, M.; Nazeeruddin, Mohammad Khaja

    2017-06-01

    Despite the impressive photovoltaic performances with power conversion efficiency beyond 22%, perovskite solar cells are poorly stable under operation, failing by far the market requirements. Various technological approaches have been proposed to overcome the instability problem, which, while delivering appreciable incremental improvements, are still far from a market-proof solution. Here we show one-year stable perovskite devices by engineering an ultra-stable 2D/3D (HOOC(CH2)4NH3)2PbI4/CH3NH3PbI3 perovskite junction. The 2D/3D forms an exceptional gradually-organized multi-dimensional interface that yields up to 12.9% efficiency in a carbon-based architecture, and 14.6% in standard mesoporous solar cells. To demonstrate the up-scale potential of our technology, we fabricate 10 × 10 cm2 solar modules by a fully printable industrial-scale process, delivering 11.2% efficiency stable for >10,000 h with zero loss in performances measured under controlled standard conditions. This innovative stable and low-cost architecture will enable the timely commercialization of perovskite solar cells.

  15. Aluminum‐Doped Cesium Lead Bromide Perovskite Nanocrystals with Stable Blue Photoluminescence Used for Display Backlight

    Science.gov (United States)

    Liu, Ming; Zhong, Guohua; Yin, Yongming; Miao, Jingsheng; Li, Ke; Wang, Chengqun; Xu, Xiuru; Shen, Clifton

    2017-01-01

    Abstract Bright and stable blue emitters with narrow full‐width at half‐maxima are particularly desirable for applications in television displays and related technologies. Here, this study shows that doping aluminum (Al3+) ion into CsPbBr3 nanocrystals (NCs) using AlBr3 can afford lead‐halide perovskites NCs with stable blue photoluminescence. First, theoretical and experimental analyses reveal that the extended band gap and quantum confinement effect of elongated shape give rise to the desirable blueshifted emission. Second, the aluminum ion incorporation path is rationalized qualitatively by invoking fundamental considerations about binding relations in AlBr3 and its dimer. Finally, the absence of anion‐exchange effect is corroborated when green CsPbBr3 and blue Al:CsPbBr3 NCs are mixed. Combinations of the above two NCs with red‐emitting CdSe@ZnS NCs result in UV‐pumped white light‐emitting diodes (LED) with an National Television System Committee (NTSC) value of 116% and ITU‐R Recommendation B.T. 2020 (Rec. 2020) of 87%. The color coordinates of the white LED are optimized at (0.32, 0.34) in CIE 1931. The results suggest that low‐cost, earth‐abundant, solution‐processable Al‐doped perovskite NCs can be promising candidate materials for blue down‐conversion layer in backlit displays. PMID:29201628

  16. Enhanced Crystalline Phase Purity of CH3NH3PbI3-xClx Film for High-Efficiency Hysteresis-Free Perovskite Solar Cells.

    Science.gov (United States)

    Yang, Yingguo; Feng, Shanglei; Xu, Weidong; Li, Meng; Li, Li; Zhang, Xingmin; Ji, Gengwu; Zhang, Xiaonan; Wang, Zhaokui; Xiong, Yimin; Cao, Liang; Sun, Baoquan; Gao, Xingyu

    2017-07-12

    Despite rapid successful developments toward promising perovskite solar cells (PSCs) efficiency, they often suffer significant hysteresis effects. Using synchrotron-based grazing incidence X-ray diffraction (GIXRD) with different probing depths by varying the incident angle, we found that the perovskite films consist of dual phases with a parent phase dominant in the interior and a child phase with a smaller (110) interplanar space (d (110) ) after rapid thermal annealing (RTA), which is a widely used post treatment to improve the crystallization of solution-processed perovskite films for high-performance planar PSCs. In particular, the child phase composition gradually increases with decreasing depth till it becomes the majority on the surface, which might be one of the key factors related to hysteresis in fabricated PSCs. We further improve the crystalline phase purity of the solution-processed CH 3 NH 3 PbI 3-x Cl x perovskite film (referred as g-perovskite) by using a facile gradient thermal annealing (GTA), which shows a uniformly distributed phase structure in pinhole-free morphology with less undercoordinated Pb and I ions determined by synchrotron-based GIXRD, grazing incidence small-angle X-ray scattering, scanning electron microscopy, and X-ray photoelectron spectroscopy. Regardless of device structures (conventional and inverted types), the planar heterojunction PSCs employing CH 3 NH 3 PbI 3-x Cl x g-perovskite films exhibit negligible hysteresis with a champion power conversion efficiency of 17.04% for TiO 2 -based conventional planar PSCs and 14.83% for poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate) (PEDOT:PSS)-based inverted planar PSCs. Our results indicate that the crystalline phase purity in CH 3 NH 3 PbI 3-x Cl x perovskite film, especially in the surface region, plays a crucial role in determining the hysteresis effect and device performance.

  17. Trapping charges at grain boundaries and degradation of CH3NH3Pb(I1-x Br x )3 perovskite solar cells

    Science.gov (United States)

    Phuong Nguyen, Bich; Kim, Gee Yeong; Jo, William; Kim, Byeong Jo; Jung, Hyun Suk

    2017-08-01

    The electrical properties of CH3NH3Pb(I1-x Br x )3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

  18. Low-cost electrodes for stable perovskite solar cells

    Science.gov (United States)

    Bastos, João P.; Manghooli, Sara; Jaysankar, Manoj; Tait, Jeffrey G.; Qiu, Weiming; Gehlhaar, Robert; De Volder, Michael; Uytterhoeven, Griet; Poortmans, Jef; Paetzold, Ulrich W.

    2017-06-01

    Cost-effective production of perovskite solar cells on an industrial scale requires the utilization of exclusively inexpensive materials. However, to date, highly efficient and stable perovskite solar cells rely on expensive gold electrodes since other metal electrodes are known to cause degradation of the devices. Finding a low-cost electrode that can replace gold and ensure both efficiency and long-term stability is essential for the success of the perovskite-based solar cell technology. In this work, we systematically compare three types of electrode materials: multi-walled carbon nanotubes (MWCNTs), alternative metals (silver, aluminum, and copper), and transparent oxides [indium tin oxide (ITO)] in terms of efficiency, stability, and cost. We show that multi-walled carbon nanotubes are the only electrode that is both more cost-effective and stable than gold. Devices with multi-walled carbon nanotube electrodes present remarkable shelf-life stability, with no decrease in the efficiency even after 180 h of storage in 77% relative humidity (RH). Furthermore, we demonstrate the potential of devices with multi-walled carbon nanotube electrodes to achieve high efficiencies. These developments are an important step forward to mass produce perovskite photovoltaics in a commercially viable way.

  19. Morphology-photovoltaic property correlation in perovskite solar cells: One-step versus two-step deposition of CH3NH3PbI3

    Directory of Open Access Journals (Sweden)

    Jeong-Hyeok Im

    2014-08-01

    Full Text Available Perovskite CH3NH3PbI3 light absorber is deposited on the mesoporous TiO2 layer via one-step and two-step coating methods and their photovoltaic performances are compared. One-step coating using a solution containing CH3NH3I and PbI2 shows average power conversion efficiency (PCE of 7.5%, while higher average PCE of 13.9% is obtained from two-step coating method, mainly due to higher voltage and fill factor. The coverage, pore-filling, and morphology of the deposited perovskite are found to be critical in photovoltaic performance of the mesoporous TiO2 based perovskite solar cells.

  20. Chlorine Incorporation in the CH3NH3PbI3 Perovskite: Small Concentration, Big Effect.

    Science.gov (United States)

    Quarti, Claudio; Mosconi, Edoardo; Umari, Paolo; De Angelis, Filippo

    2017-01-03

    The role of chlorine doping in CH 3 NH 3 PbI 3 represents an important open issue in the use of hybrid perovskites for photovoltaic applications. In particular, even if a positive role of chlorine doping on perovskite film formation and on material morphology has been demonstrated, an inherent positive effect on the electronic and photovoltaic properties cannot be excluded. Here we carried out periodic density functional theory and Car-Parrinello molecular dynamics simulations, going down to ∼1% doping, to investigate the effect of chlorine on CH 3 NH 3 PbI 3 . We found that such a small doping has important effects on the dynamics of the crystalline structure, both with respect to the inorganic framework and with respect to the cation libration motion. Together, we observe a dynamic spatial localization of the valence and conduction states in separated spatial material regions, which takes place in the 10 -1 ps time scale and which could be the key to ease of exciton dissociation and, likely, to small charge recombination in hybrid perovskites. Moreover, such localization is enhanced by chlorine doping, demonstrating an inherent positive role of chlorine doping on the electronic properties of this class of materials.

  1. Engineering of CH 3 NH 3 PbI 3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties

    KAUST Repository

    Peng, Wei; Miao, Xiaohe; Adinolfi, Valerio; Alarousu, Erkki; El Tall, Omar; Emwas, Abdul-Hamid M.; Zhao, Chao; Walters, Grant; Liu, Jiakai; Ouellette, Olivier; Pan, Jun; Banavoth, Murali; Sargent, Edward H.; Mohammed, Omar F.; Bakr, Osman

    2016-01-01

    The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite's three-dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.

  2. Crystallographic and Electronic Structure of the Sr3Sb2CoO9 Triple Perovskite

    International Nuclear Information System (INIS)

    González, W; Téllez, D A Landínez; Roa-Rojas, J; Cardona, R

    2014-01-01

    Compounds The perovskites are materials with physical and chemical characteristics that make them optimal for application in the technological and scientist. When the ideal formula of perovskite ABO 3 is modified by introducing a special structural arrangement can get to get triple perovskites, which correspond to the formula A 3 B 2 B'O 9 . In this work we report the synthesis process and the study of electronic structure and crystal Sr 3 Sb 2 CoO 9 new triple perovskite. From the experiments of X-ray Diffraction and the application of the Rietveld refinement method was revealed that the system crystallizes in a perovskite structure with a characteristic triple given by the space group Immm (#71) and lattice parameters a=9.791(9) Å, b=5.656(7) Å and c=16.957(8) Å. Ab initio calculations of density of states (DOS) and electronic structure were carried out for this perovskite-like system by using the Quantum EXPRESSO code. The exchange-correlation potential was treated using the Generalized Gradient Approximation (GGA). All calculations were carried-out using spin polarization.

  3. Enhanced photovoltaic performance of CH3NH3PbBrXI3-X-based perovskite solar cells via anti-solvent extraction

    Science.gov (United States)

    Jiang, Zhaoyi; Zhang, Weijia; Lu, Chaoqun; Ma, Denghao; Liu, Haixu; Yu, Wei; Zhang, Yu; Ma, Qiang; Zhang, Yulong

    2018-06-01

    In this paper, the two-step sequential deposition method was used to prepare the CH3NH3PbBrXI3-X films by introducing CH3NH3Br in the precursors. The surface morphology of the PbI2 films was controlled by anti-solvent extraction (ASE) to improve the microstructure and photo-physical properties of the perovskite films. It was noteworthy that, compared to the compact PbI2 films, the porous PbI2 films facilitated the growth of crystals and bromine incorporation in films, and the prepared perovskite films exhibited enlarged grain size, increased light absorption, enhanced Br incorporation and prolonged carrier lifetime, which resulted in excellent photo-electrical properties of the CH3NH3PbBrXI3-X films. With porous PbI2 templates, the inverted planar perovskite solar cells based on films with appropriate Br incorporation (CH3NH3Br/CH3NH3I mole ratio = 3/7) showed a photovoltaic conversion efficiency (PCE) of 14.9%, and the stability of the devices in air was elevated. Consequently, the high-quality CH3NH3PbBrXI3-X films can be obtained with porous PbI2 templates for improving the performance of the perovskite solar cells.

  4. Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 perovskites for solar cell applications.

    Science.gov (United States)

    Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

    2014-03-26

    Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I(1-x)Cl(x))3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

  5. Direct Vapor Growth of Perovskite CsPbBr3 Nanoplate Electroluminescence Devices.

    Science.gov (United States)

    Hu, Xuelu; Zhou, Hong; Jiang, Zhenyu; Wang, Xiao; Yuan, Shuangping; Lan, Jianyue; Fu, Yongping; Zhang, Xuehong; Zheng, Weihao; Wang, Xiaoxia; Zhu, Xiaoli; Liao, Lei; Xu, Gengzhao; Jin, Song; Pan, Anlian

    2017-10-24

    Metal halide perovskite nanostructures hold great promises as nanoscale light sources for integrated photonics due to their excellent optoelectronic properties. However, it remains a great challenge to fabricate halide perovskite nanodevices using traditional lithographic methods because the halide perovskites can be dissolved in polar solvents that are required in the traditional device fabrication process. Herein, we report single CsPbBr 3 nanoplate electroluminescence (EL) devices fabricated by directly growing CsPbBr 3 nanoplates on prepatterned indium tin oxide (ITO) electrodes via a vapor-phase deposition. Bright EL occurs in the region near the negatively biased contact, with a turn-on voltage of ∼3 V, a narrow full width at half-maximum of 22 nm, and an external quantum efficiency of ∼0.2%. Moreover, through scanning photocurrent microscopy and surface electrostatic potential measurements, we found that the formation of ITO/p-type CsPbBr 3 Schottky barriers with highly efficient carrier injection is essential in realizing the EL. The formation of the ITO/p-type CsPbBr 3 Schottky diode is also confirmed by the corresponding transistor characteristics. The achievement of EL nanodevices enabled by directly grown perovskite nanostructures could find applications in on-chip integrated photonics circuits and systems.

  6. Optical constants of CH3NH3PbBr3 perovskite thin films measured by spectroscopic ellipsometry

    KAUST Repository

    Alias, Mohd Sharizal

    2016-07-14

    The lack of optical constants information for hybrid perovskite of CH3NH3PbBr3 in thin films form can delay the progress of efficient LED or laser demonstration. Here, we report on the optical constants (complex refractive index and dielectric function) of CH3NH3PbBr3 perovskite thin films using spectroscopic ellipsometry. Due to the existence of voids, the refractive index of the thin films is around 8% less than the single crystals counterpart. The energy bandgap is around 2.309 eV as obtained from photoluminescence and spectrophotometry spectra, and calculated from the SE analysis. The precise measurement of optical constants will be useful in designing optical devices using CH3NH3PbBr3 thin films.

  7. Trace Element Abundances in an Unusual Hibonite-Perovskite Refractory Inclusion from Allende

    Science.gov (United States)

    Mane, Prajkta; Wadhwa, M.; Keller, L. P.

    2013-01-01

    Calcium-aluminum-rich refractory inclusions (CAIs) are thought to be the first-formed solids in the Solar protoplanetary disk and can provide information about the earliest Solar System processes (e.g., [1]). A hibonite-perovskitebearing CAI from the Allende CV3 chondrite (SHAL, [2]) contains a single of 500 micrometers hibonite grain and coarse-grained perovskite. The mineralogy and oxygen isotopic composition of this CAI shows similarities with FUN inclusions, especially HAL [2]. Here we present trace element abundances in SHAL.

  8. CH3NH3PbI3 grain growth and interfacial properties in meso-structured perovskite solar cells fabricated by two-step deposition

    Science.gov (United States)

    Yao, Zhibo; Wang, Wenli; Shen, Heping; Zhang, Ye; Luo, Qiang; Yin, Xuewen; Dai, Xuezeng; Li, Jianbao; Lin, Hong

    2017-12-01

    Although the two-step deposition (TSD) method is widely adopted for the high performance perovskite solar cells (PSCs), the CH3NH3PbI3 perovskite crystal growth mechanism during the TSD process and the photo-generated charge recombination dynamics in the mesoporous-TiO2 (mp-TiO2)/CH3NH3PbI3/hole transporting material (HTM) system remains unexploited. Herein, we modified the concentration of PbI2 (C(PbI2)) solution to control the perovskite crystal properties, and observed an abnormal CH3NH3PbI3 grain growth phenomenon atop mesoporous TiO2 film. To illustrate this abnormal grain growth mechanism, we propose that a grain ripening process is taking place during the transformation from PbI2 to CH3NH3PbI3, and discuss the PbI2 nuclei morphology, perovskite grain growing stage, as well as Pb:I atomic ratio difference among CH3NH3PbI3 grains with different morphology. These C(PbI2)-dependent perovskite morphologies resulted in varied charge carrier transfer properties throughout the mp-TiO2/CH3NH3PbI3/HTM hybrid, as illustrated by photoluminescence measurement. Furthermore, the effect of CH3NH3PbI3 morphology on light absorption and interfacial properties is investigated and correlated with the photovoltaic performance of PSCs.

  9. Copper-Substituted Lead Perovskite Materials Constructed with Different Halides for Working (CH3NH3)2CuX4-Based Perovskite Solar Cells from Experimental and Theoretical View.

    Science.gov (United States)

    Elseman, Ahmed Mourtada; Shalan, Ahmed Esmail; Sajid, Sajid; Rashad, Mohamed Mohamed; Hassan, Ali Mostafa; Li, Meicheng

    2018-04-11

    Toxicity and chemical instability issues of halide perovskites based on organic-inorganic lead-containing materials still remain as the main drawbacks for perovskite solar cells (PSCs). Herein, we discuss the preparation of copper (Cu)-based hybrid materials, where we replace lead (Pb) with nontoxic Cu metal for lead-free PSCs, and investigate their potential toward solar cell applications based on experimental and theoretical studies. The formation of (CH 3 NH 3 ) 2 CuX 4 [(CH 3 NH 3 ) 2 CuCl 4 , (CH 3 NH 3 ) 2 CuCl 2 I 2 , and (CH 3 NH 3 ) 2 CuCl 2 Br 2 ] was discussed in details. Furthermore, it was found that chlorine (Cl - ) in the structure is critical for the stabilization of the formed compounds. Cu-based perovskite-like materials showed attractive absorbance features extended to the near-infrared range, with appropriate band gaps. Green photoluminescence of these materials was obtained because of Cu + ions. The power conversion efficiency was measured experimentally and estimated theoretically for different architectures of solar cell devices.

  10. CsPbBr3:xEu3+ perovskite QD borosilicate glass: a new member of the luminescent material family.

    Science.gov (United States)

    Yuan, Rongrong; Shen, Lingli; Shen, Chenyang; Liu, Jianming; Zhou, Lei; Xiang, Weidong; Liang, Xiaojuan

    2018-03-29

    Eu3+ ions were introduced into the lattices of CsPbBr3 perovskite QDs and a tunable multicolour emission from CsPbBr3:xEu3+ perovskite QD glass was successfully obtained. Multicolour LEDs that were fabricated by combining the as-prepared CsPbBr3:xEu3+ QD glasses with a UV chip were also researched in this study.

  11. Structural characterization of a new vacancy ordered perovskite modification found for Ba3Fe3O7F (BaFeO2.333F0.333): Towards understanding of vacancy ordering for different perovskite-type ferrites

    International Nuclear Information System (INIS)

    Clemens, Oliver

    2015-01-01

    The new vacancy ordered perovskite-type compound Ba 3 Fe 3 O 7 F (BaFeO 2.33 F 0.33 ) was prepared by topochemical low-temperature fluorination of Ba 2 Fe 2 O 5 (BaFeO 2.5 ) using stoichiometric amounts of polyvinylidene difluoride (PVDF). The vacancy order was found to be unique so far for perovskite compounds, and the connectivity pattern can be explained by the formula Ba 3 (FeX 6/2 ) (FeX 5/2 ) (FeX 3/2 X 1/1 ), with X=O/F. Mössbauer measurements were used to confirm the structural analysis and agree with the presence of Fe 3+ in the above mentioned coordination environments. Group–subgroup relationships were used to build a starting model for the structure solution and to understand the relationship to the cubic perovskite structure. Furthermore, a comparison of a variety of vacancy-ordered iron-containing perovskite-type structures is given, highlighting the factors which favour one structure type over the other depending on the composition. - Graphical abstract: The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. - Highlights: • The crystal structure of Ba 3 Fe 3 O 7 F in comparison to other perovskite type ferrites. • Ba 3 Fe 3 O 7 F was synthesized by low temperature fluorination of Ba 2 Fe 2 O 5 . • Ba 3 Fe 3 O 7 F shows a unique vacancy order not found for other perovskite type compounds. • The structure of Ba 3 Fe 3 O 7 F was solved using group–subgroup relationships. • A systematic comparison to other ferrite type compounds reveals structural similarities and differences. • The A-site coordination of the cation is shown to play an important role for the type of vacancy order found

  12. Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting

    Directory of Open Access Journals (Sweden)

    Govindhasamy Murugadoss

    2014-08-01

    Full Text Available In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.

  13. Effects of CuBr addition to CH3NH3PbI3(Cl) perovskite photovoltaic devices

    Science.gov (United States)

    Oku, Takeo; Ohishi, Yuya; Tanaka, Hiroki

    2018-01-01

    Effects of CuBr addition to perovskite CH3NH3PbI3(Cl) precursor solutions on photovoltaic properties were investigated. The CH3NH3Pb(Cu)I3(Cl,Br)-based photovoltaic devices were fabricated by a spin-coating technique, and the microstructures of the devices were investigated by X-ray diffraction, optical microscopy and scanning electron microscopy. Current density-voltage characteristics were improved by a small amount of CuBr addition, which resulted in improvement of the conversion efficiencies of the devices. The structure analysis showed decrease of unit cell volume and increase of Cu/Br composition by the CuBr addition, which would indicate the Cu/Br substitution at the Pb/I sites in the perovskite crystal, respectively.

  14. Dependence of Acetate-Based Antisolvents for High Humidity Fabrication of CH3NH3PbI3 Perovskite Devices in Ambient Atmosphere.

    Science.gov (United States)

    Yang, Fu; Kapil, Gaurav; Zhang, Putao; Hu, Zhaosheng; Kamarudin, Muhammad Akmal; Ma, Tingli; Hayase, Shuzi

    2018-05-16

    High-efficiency perovskite solar cells (PSCs) need to be fabricated in the nitrogen-filled glovebox by the atmosphere-controlled crystallization process. However, the use of the glovebox process is of great concern for mass level production of PSCs. In this work, notable efficient CH 3 NH 3 PbI 3 solar cells can be obtained in high humidity ambient atmosphere (60-70% relative humidity) by using acetate as the antisolvent, in which dependence of methyl, ethyl, propyl, and butyl acetate on the crystal growth mechanism is discussed. It is explored that acetate screens the sensitive perovskite intermediate phases from water molecules during perovskite film formation and annealing. It is revealed that relatively high vapor pressure and high water solubility of methyl acetate (MA) leads to the formation of highly dense and pinhole free perovskite films guiding to the best power conversion efficiency (PCE) of 16.3% with a reduced hysteresis. The devices prepared using MA showed remarkable shelf life stability of more than 80% for 360 h in ambient air condition, when compared to the devices fabricated using other antisolvents with low vapor pressure and low water solubility. Moreover, the PCE was still kept at 15.6% even though 2 vol % deionized water was added in the MA for preparing the perovskite layer.

  15. Formation Dynamics of CH3NH3PbI3 Perovskite Following Two-Step Layer Deposition.

    Science.gov (United States)

    Patel, Jay B; Milot, Rebecca L; Wright, Adam D; Herz, Laura M; Johnston, Michael B

    2016-01-07

    Hybrid metal-halide perovskites have emerged as a leading class of semiconductors for optoelectronic devices because of their desirable material properties and versatile fabrication methods. However, little is known about the chemical transformations that occur in the initial stages of perovskite crystal formation. Here we follow the real-time formation dynamics of MAPbI3 from a bilayer of lead iodide (PbI2) and methylammonium iodide (MAI) deposited through a two-step thermal evaporation process. By lowering the substrate temperature during deposition, we are able to initially inhibit intermixing of the two layers. We subsequently use infrared and visible light transmission, X-ray diffraction, and photoluminescence lifetime measurements to reveal the room-temperature transformations that occur in vacuum and ambient air, as MAI diffuses into the PbI2 lattice to form MAPbI3. In vacuum, the transformation to MAPbI3 is incomplete as unreacted MAI is retained in the film. However, exposure to moist air allows for conversion of the unreacted MAI to MAPbI3, demonstrating that moisture is essential in making MAI more mobile and thus aiding perovskite crystallization. These dynamic processes are reflected in the observed charge-carrier lifetimes, which strongly fluctuate during periods of large ion migration but steadily increase with improving crystallinity.

  16. Light-Independent Ionic Transport in Inorganic Perovskite and Ultrastable Cs-Based Perovskite Solar Cells.

    Science.gov (United States)

    Zhou, Wenke; Zhao, Yicheng; Zhou, Xu; Fu, Rui; Li, Qi; Zhao, Yao; Liu, Kaihui; Yu, Dapeng; Zhao, Qing

    2017-09-07

    Due to light-induced effects in CH 3 NH 3 -based perovskites, such as ion migration, defects formation, and halide segregation, the degradation of CH 3 NH 3 -based perovskite solar cells under maximum power point is generally implicated. Here we demonstrated that the effect of light-enhanced ion migration in CH 3 NH 3 PbI 3 can be eliminated by inorganic Cs substitution, leading to an ultrastable perovskite solar cell. Quantitatively, the ion migration barrier for CH 3 NH 3 PbI 3 is 0.62 eV under dark conditions, larger than that of CsPbI 2 Br (0.45 eV); however, it reduces to 0.07 eV for CH 3 NH 3 PbI 3 under illumination, smaller than that for CsPbI 2 Br (0.43 eV). Meanwhile, photoinduced halide segregation is also suppressed in Cs-based perovskites. Cs-based perovskite solar cells retained >99% of the initial efficiency (10.3%) after 1500 h of maximum power point tracking under AM1.5G illumination, while CH 3 NH 3 PbI 3 solar cells degraded severely after 50 h of operation. Our work reveals an uncovered mechanism for stability improvement by inorganic cation substitution in perovskite-based optoelectronic devices.

  17. Nature of potential barrier in (Ca 1/4,Cu 3/4)TiO 3 polycrystalline perovskite

    Science.gov (United States)

    Marques, V. P. B.; Bueno, P. R.; Simões, A. Z.; Cilense, M.; Varela, J. A.; Longo, E.; Leite, E. R.

    2006-04-01

    The nonohmic electrical features of (Ca 1/4,Cu 3/4)TiO 3 perovskite ceramics, which have very strong gigantic dielectric is believed originate from potential barriers at the grain boundaries. In the present study, we used the admittance and impedance spectroscopy technique to investigate (Ca 1/4,Cu 3/4)TiO 3 perovskite ceramics with low nonohmic electrical properties. The study was conducted under two different conditions: on as-sintered ceramics and on ceramics thermally treated in an oxygen-rich atmosphere. The results confirm that thermal treatment in oxygen-rich atmospheres influence the nonohmic properties. Annealing at oxygen-rich atmospheres improve the nonohmic behavior and annealing at oxygen-poor atmospheres decrease the nonohmic properties, a behavior already reported for common metal oxide nonohmic devices and here firstly evidenced for the (Ca 1/4,Cu 3/4)TiO 3 perovskite related materials. The results show that oxygen also influences the capacitance values at low frequencies, a behavior that is indicative of the Schottky-type nature of the potential barrier.

  18. Cerium luminescence in nd0 perovskites

    International Nuclear Information System (INIS)

    Setlur, A.A.; Happek, U.

    2010-01-01

    The luminescence of Ce 3+ in perovskite (ABO 3 ) hosts with nd 0 B-site cations, specifically Ca(Hf,Zr)O 3 and (La,Gd)ScO 3 , is investigated in this report. The energy position of the Ce 3+ excitation and emission bands in these perovskites is compared to those of typical Al 3+ perovskites; we find a Ce 3+ 5d 1 centroid shift and Stokes shift that are larger versus the corresponding values for the Al 3+ perovskites. It is also shown that Ce 3+ luminescence quenching is due to Ce 3+ photoionization. The comparison between these perovskites shows reasonable correlations between Ce 3+ luminescence quenching, the energy position of the Ce 3+ 5d 1 excited state with respect to the host conduction band, and the host composition. - Graphical abstract: Ce 3+ decay times versus temperature for perovskites with nd 0 B-site cations.

  19. Photoresponse of CsPbBr3 and Cs4PbBr6 Perovskite Single Crystals.

    Science.gov (United States)

    Cha, Ji-Hyun; Han, Jae Hoon; Yin, Wenping; Park, Cheolwoo; Park, Yongmin; Ahn, Tae Kyu; Cho, Jeong Ho; Jung, Duk-Young

    2017-02-02

    High-quality and millimeter-sized perovskite single crystals of CsPbBr 3 and Cs 4 PbBr 6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr 3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs 4 PbBr 6 crystals, which have a 0D perovskite structure, exhibited more than 1 order of magnitude higher PL intensity than CsPbBr 3 , which generated an ultralow photoresponse under illumination. Their contrasting optoelectrical characteristics were attributed to different exciton binding energies, induced by coordination geometry of the [PbBr 6 ] 4- octahedron sublattices. This work correlated the local structures of lead in the primitive perovskite and its derivatives to PL spectra as well as photoconductivity.

  20. Perovskite-Perovskite Homojunctions via Compositional Doping.

    Science.gov (United States)

    Dänekamp, Benedikt; Müller, Christian; Sendner, Michael; Boix, Pablo P; Sessolo, Michele; Lovrincic, Robert; Bolink, Henk J

    2018-05-11

    One of the most important properties of semiconductors is the possibility of controlling their electronic behavior via intentional doping. Despite the unprecedented progress in the understanding of hybrid metal halide perovskites, extrinsic doping of perovskite remains nearly unexplored and perovskite-perovskite homojunctions have not been reported. Here we present a perovskite-perovskite homojunction obtained by vacuum deposition of stoichiometrically tuned methylammonium lead iodide (MAPI) films. Doping is realized by adjusting the relative deposition rates of MAI and PbI 2 , obtaining p-type (MAI excess) and n-type (MAI defect) MAPI. The successful stoichiometry change in the thin films is confirmed by infrared spectroscopy, which allows us to determine the MA content in the films. We analyzed the resulting thin-film junction by cross-sectional scanning Kelvin probe microscopy (SKPM) and found a contact potential difference (CPD) of 250 mV between the two differently doped perovskite layers. Planar diodes built with the perovskite-perovskite homojunction show the feasibility of our approach for implementation in devices.

  1. Constructing Efficient and Stable Perovskite Solar Cells via Interconnecting Perovskite Grains.

    Science.gov (United States)

    Hou, Xian; Huang, Sumei; Ou-Yang, Wei; Pan, Likun; Sun, Zhuo; Chen, Xiaohong

    2017-10-11

    A high-quality perovskite film with interconnected perovskite grains was obtained by incorporating terephthalic acid (TPA) additive into the perovskite precursor solution. The presence of TPA changed the crystallization kinetics of the perovskite film and promoted lateral growth of grains in the vicinity of crystal boundaries. As a result, sheet-shaped perovskite was formed and covered onto the bottom grains, which made some adjacent grains partly merge together to form grains-interconnected perovskite film. Perovskite solar cells (PSCs) with TPA additive exhibited a power conversion efficiency (PCE) of 18.51% with less hysteresis, which is obviously higher than that of pristine cells (15.53%). PSCs without and with TPA additive retain 18 and 51% of the initial PCE value, respectively, aging for 35 days exposed to relative humidity 30% in air without encapsulation. Furthermore, MAPbI 3 film with TPA additive shows superior thermal stability to the pristine one under 100 °C baking. The results indicate that the presence of TPA in perovskite film can greatly improve the performance of PSCs as well as their moisture resistance and thermal stability.

  2. Fullerene-Based Electron Transport Layers for Semi-Transparent MAPbBr3 Perovskite Films in Planar Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2016-10-01

    Full Text Available In this study, four kinds of structures—[6,6]-phenyl-C61-butyric acid methyl ester (PCBM, PCBM/fullerene (C60, C60/bathocuproine (BCP, and PCBM/C60/BCP—were used as electron transport layers, and the structure, and optical and electronic behaviors of MAPbBr3 perovskite layers after annealing treatments were observed. The experimental results indicate that PCBM/C60 bi-layer structure is acceptable for MAPbBr3 planar perovskite solar cells due to electron step transporting. Low-temperature annealing is suitable for smooth and large grain MAPbBr3 films. The semi-transparent yellow C60/PCBM/MAPbBr3/PEDOT:PSS/ITO glass-structure solar cells exhibit the best performance with a power conversion efficiency of 4.19%. The solar cells are revealed to be suitable for application in building integrated photovoltaic (BIPV systems.

  3. Stability Issues on Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Xing Zhao

    2015-11-01

    Full Text Available Organo lead halide perovskite materials like methylammonium lead iodide (CH3NH3PbI3 and formamidinium lead iodide (HC(NH22PbI3 show superb opto-electronic properties. Based on these perovskite light absorbers, power conversion efficiencies of the perovskite solar cells employing hole transporting layers have increased from 9.7% to 20.1% within just three years. Thus, it is apparent that perovskite solar cell is a promising next generation photovoltaic technology. However, the unstable nature of perovskite was observed when exposing it to continuous illumination, moisture and high temperature, impeding the commercial development in the long run and thus becoming the main issue that needs to be solved urgently. Here, we discuss the factors affecting instability of perovskite and give some perspectives about further enhancement of stability of perovskite solar cell.

  4. Al2 O3 Underlayer Prepared by Atomic Layer Deposition for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Zhang, Jinbao; Hultqvist, Adam; Zhang, Tian; Jiang, Liangcong; Ruan, Changqing; Yang, Li; Cheng, Yibing; Edoff, Marika; Johansson, Erik M J

    2017-10-09

    Perovskite solar cells, as an emergent technology for solar energy conversion, have attracted much attention in the solar cell community by demonstrating impressive enhancement in power conversion efficiencies. However, the high temperature and manually processed TiO 2 underlayer prepared by spray pyrolysis significantly limit the large-scale application and device reproducibility of perovskite solar cells. In this study, lowtemperature atomic layer deposition (ALD) is used to prepare a compact Al 2 O 3 underlayer for perovskite solar cells. The thickness of the Al 2 O 3 layer can be controlled well by adjusting the deposition cycles during the ALD process. An optimal Al 2 O 3 layer effectively blocks electron recombination at the perovskite/fluorine-doped tin oxide interface and sufficiently transports electrons through tunneling. Perovskite solar cells fabricated with an Al 2 O 3 layer demonstrated a highest efficiency of 16.2 % for the sample with 50 ALD cycles (ca. 5 nm), which is a significant improvement over underlayer-free PSCs, which have a maximum efficiency of 11.0 %. Detailed characterization confirms that the thickness of the Al 2 O 3 underlayer significantly influences the charge transfer resistance and electron recombination processes in the devices. Furthermore, this work shows the feasibility of using a high band-gap semiconductor such as Al 2 O 3 as the underlayer in perovskite solar cells and opens up pathways to use ALD Al 2 O 3 underlayers for flexible solar cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping.

    Science.gov (United States)

    Begum, Raihana; Parida, Manas R; Abdelhady, Ahmed L; Murali, Banavoth; Alyami, Noktan M; Ahmed, Ghada H; Hedhili, Mohamed Nejib; Bakr, Osman M; Mohammed, Omar F

    2017-01-18

    Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr 3 perovskite NCs with heterovalent Bi 3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.

  6. Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping

    KAUST Repository

    Begum, Raihana

    2016-12-17

    Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr3 perovskite NCs with heterovalent Bi3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.

  7. Influence of iridium on the reactivity of LaFeO3 base perovskites

    DEFF Research Database (Denmark)

    Kindermann, L.; Das, D.; Bahadur, D.

    1998-01-01

    The influence of iridium on the reactivity of powder mixtures made of perovskites and 8 mol% yttria stabilized zirconia (8 YSZ) is reported. Iridium is added to the perovskites of the composition (La0.6M0.4)(z)Fe0.8TM0.2O3-delta (M = Sr, Ca; TM = Mn, Co; z = 0.90, 1.00) via the gaseous phase....... Iridium is present in the perovskite lattice as Ir4+ replacing iron as is evident from XRD and TEM/EDX results. Compatibility studies carried out at 1000 degrees C demonstrate that iridium has considerable influence on the reactivity. The results are discussed with respect to the stability...... of the perovskites, thermodynamic activities, Ir(IV)-O bonding, tolerance factor and oxygen migration....

  8. Hybrid perovskite resulting from the solid-state reaction between the organic cations and perovskite layers of alpha1-(Br-(CH(2))(2)-NH(3))(2)PbI(4).

    Science.gov (United States)

    Sourisseau, Sebastien; Louvain, Nicolas; Bi, Wenhua; Mercier, Nicolas; Rondeau, David; Buzaré, Jean-Yves; Legein, Christophe

    2007-07-23

    The alpha1-(Br-(CH(2))(2)-NH(3))(2)PbI(4) hybrid perovskite undergoes a solid-state transformation, that is, the reaction between the organic cations and the perovskite layers to give the new hybrid perovskite (Br-(CH(2))(2)-NH(3))(2-x)(I-(CH(2))(2)-NH(3))(x)PbBr(x)I(4-x), based on mixed halide inorganic layers. This transformation has been followed by a conventional powder X-ray diffraction system equipped with a super speed detector, and both solid-state (13)C NMR and ESI/MS measurements have been adopted in the estimation of the rate of halide substitution. The first reaction step leads to the special composition of x approximately 1 (A phase), while the complete substitution is not achieved even at elevated temperature (x(max) approximately 1.85 (B phase)). This unprecedented solid-state reaction between organic and inorganic components of a hybrid perovskite can be considered as a completely new strategy to achieve interesting hybrid perovskites.

  9. Homogeneous Synthesis and Electroluminescence Device of Highly Luminescent CsPbBr3 Perovskite Nanocrystals.

    Science.gov (United States)

    Wei, Song; Yang, Yanchun; Kang, Xiaojiao; Wang, Lan; Huang, Lijian; Pan, Daocheng

    2017-03-06

    Highly luminescent CsPbBr 3 perovskite nanocrystals (PNCs) are homogeneously synthesized by mixing toluene solutions of PbBr 2 and cesium oleate at room temperature in open air. We found that PbBr 2 can be easily dissolved in nonpolar toluene in the presence of tetraoctylammonium bromide, which allows us to homogeneously prepare CsPbBr 3 perovskite quantum dots and prevents the use of harmful polar organic solvents, such as N,N-dimethylformamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone. Additionally, this method can be extended to synthesize highly luminescent CH 3 NH 3 PbBr 3 perovskite quantum dots. An electroluminescence device with a maximal luminance of 110 cd/m 2 has been fabricated by using high-quality CsPbBr 3 PNCs as the emitting layer.

  10. Curtailing Perovskite Processing Limitations via Lamination at the Perovskite/Perovskite Interface

    Energy Technology Data Exchange (ETDEWEB)

    Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moore, David [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Christians, Jeffrey A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Beard, Matthew C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Berry, Joseph J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dunfield, Sean P. [University of Colorado; Fabian, David M. [University of California Irvine; Dixon, Alex G. [University of Colorado; Dou, Benjia [University of Colorado; Ardo, Shane [University of California Irvine; Shaheen, Sean E. [University of Colorado

    2018-04-24

    Standard layer-by-layer solution processing methods constrain lead-halide perovskite device architectures. The layer below the perovskite must be robust to the strong organic solvents used to form the perovskite while the layer above has a limited thermal budget and must be processed in nonpolar solvents to prevent perovskite degradation. To circumvent these limitations, we developed a procedure where two transparent conductive oxide/transport material/perovskite half stacks are independently fabricated and then laminated together at the perovskite/perovskite interface. Using ultraviolet-visible absorption spectroscopy, external quantum efficiency, X-ray diffraction, and time-resolved photoluminesence spectroscopy, we show that this procedure improves photovoltaic properties of the perovskite layer. Applying this procedure, semitransparent devices employing two high-temperature oxide transport layers were fabricated, which realized an average efficiency of 9.6% (maximum: 10.6%) despite series resistance limitations from the substrate design. Overall, the developed lamination procedure curtails processing constraints, enables new device designs, and affords new opportunities for optimization.

  11. Calcium doped MAPbI3 with better energy state alignment in perovskite solar cells

    Science.gov (United States)

    Lu, Chaojie; Zhang, Jing; Hou, Dagang; Gan, Xinlei; Sun, Hongrui; Zeng, Zhaobing; Chen, Renjie; Tian, Hui; Xiong, Qi; Zhang, Ying; Li, Yuanyuan; Zhu, Yuejin

    2018-05-01

    The organic-inorganic perovskite material with better energy alignment in the solar cell device will have a profound impact on the solar cell performance. It is valuable to tune the energy states by element substitution and doping in perovskites. Here, we present that Ca2+ is incorporated into CH3NH3PbI3, which up-shifts the valence band maximum and the conduction band minimum, leading to a difference between the bandgap and the Fermi level in the device. Consequently, Ca2+ incorporation results in an enhancement of the photovoltage and photocurrent, achieving a summit efficiency of 18.3% under standard 1 sun (AM 1.5). This work reveals the doped perovskite to improve the solar cell performance by tuning the energy state.

  12. Highly Efficient 2D/3D Hybrid Perovskite Solar Cells via Low-Pressure Vapor-Assisted Solution Process.

    Science.gov (United States)

    Li, Ming-Hsien; Yeh, Hung-Hsiang; Chiang, Yu-Hsien; Jeng, U-Ser; Su, Chun-Jen; Shiu, Hung-Wei; Hsu, Yao-Jane; Kosugi, Nobuhiro; Ohigashi, Takuji; Chen, Yu-An; Shen, Po-Shen; Chen, Peter; Guo, Tzung-Fang

    2018-06-08

    The fabrication of multidimensional organometallic halide perovskite via a low-pressure vapor-assisted solution process is demonstrated for the first time. Phenyl ethyl-ammonium iodide (PEAI)-doped lead iodide (PbI 2 ) is first spin-coated onto the substrate and subsequently reacts with methyl-ammonium iodide (MAI) vapor in a low-pressure heating oven. The doping ratio of PEAI in MAI-vapor-treated perovskite has significant impact on the crystalline structure, surface morphology, grain size, UV-vis absorption and photoluminescence spectra, and the resultant device performance. Multiple photoluminescence spectra are observed in the perovskite film starting with high PEAI/PbI 2 ratio, which suggests the coexistence of low-dimensional perovskite (PEA 2 MA n -1 Pb n I 3 n +1 ) with various values of n after vapor reaction. The dimensionality of the as-fabricated perovskite film reveals an evolution from 2D, hybrid 2D/3D to 3D structure when the doping level of PEAI/PbI 2 ratio varies from 2 to 0. Scanning electron microscopy images and Kelvin probe force microscopy mapping show that the PEAI-containing perovskite grain is presumably formed around the MAPbI 3 perovskite grain to benefit MAPbI 3 grain growth. The device employing perovskite with PEAI/PbI 2 = 0.05 achieves a champion power conversion efficiency of 19.10% with an open-circuit voltage of 1.08 V, a current density of 21.91 mA cm -2 , and a remarkable fill factor of 80.36%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Low temperature synthesis and photocatalytic property of perovskite-type LaCoO3 hollow spheres

    International Nuclear Information System (INIS)

    Fu, Shasha; Niu, Helin; Tao, Zhiyin; Song, Jiming; Mao, Changjie; Zhang, Shengyi; Chen, Changle; Wang, Dong

    2013-01-01

    Highlights: •Hollow perovskite-type LaCoO 3 is fabricated by green colloidal template method. •Carbonaceous colloids acted as templates and offered internal heat source. •The calcination temperature to form perovskite-type LaCoO 3 was dropped to 550 °C. •The photocatalytic properties were studied upon UV irradiation. •Hollow perovskite-type LaCoO 3 shows excellent photocatalytic activity on dyes. -- Abstract: Hollow perovskite-type LaCoO 3 was successfully fabricated by surface-ion adsorption method utilizing the carbonaceous colloids as template under relatively low calcination temperature. Carbonaceous colloids not only acted as templates but also offered internal heat source during calcination process. The impact of calcined temperature and time on the structure and morphology of the product were studied and the possible formation process of perovskite-type LaCoO 3 hollow spheres was illustrated. The obtained product was characterized by SEM, TEM, XRD, TG-DSC, ICP-OES, BET and UV–visible absorption spectra. The photocatalytic activities for degradation of methylene blue, methyl orange and neutral red were tested. The good photocatalytic degradation activity of the three different dyes and the band gap of 2.07 eV make it a promising candidate material for photocatalytic applications

  14. Improvement of CH3NH3PbI3 thin film using the additive 1,8-diiodooctane for planar heterojunction perovskite cells

    Science.gov (United States)

    Abdulrahman, Solh; Wang, Chunhua; Cao, Chenghao; Zhang, Chujun; Yang, Junliang; Jiang, Li

    2017-10-01

    The thin-film quality is critical for obtaining high-performance perovskite solar cells (PSCs). The additive 1,8-diiodooctane (DIO) was used to control the morphology and structure of CH3NH3PbI3 perovskite thin films, and planar heterojunction (PHJ) PSCs with an architecture of ITO/PEDOT: PSS/CH3NH3PbI3/PCBM/Al was fabricated. It was found that the DIO played an important role on CH3NH3PbI3 thin-film quality and the performance of PHJ-PSCs. With the optimal volume ratio of 2%, the compact and uniform high-quality CH3NH3PbI3 thin films with enhanced crystallinity and less roughness were achieved, resulting in the great improvement of power conversion efficiency (PCE) from about 4.5% to over 9.0%. The research results indicate that the additive DIO is a simple and effective method to produce high-quality perovskite thin film and accordingly develop high-performance PHJ-PSCs.

  15. Predictions of new AB O3 perovskite compounds by combining machine learning and density functional theory

    Science.gov (United States)

    Balachandran, Prasanna V.; Emery, Antoine A.; Gubernatis, James E.; Lookman, Turab; Wolverton, Chris; Zunger, Alex

    2018-04-01

    We apply machine learning (ML) methods to a database of 390 experimentally reported A B O3 compounds to construct two statistical models that predict possible new perovskite materials and possible new cubic perovskites. The first ML model classified the 390 compounds into 254 perovskites and 136 that are not perovskites with a 90% average cross-validation (CV) accuracy; the second ML model further classified the perovskites into 22 known cubic perovskites and 232 known noncubic perovskites with a 94% average CV accuracy. We find that the most effective chemical descriptors affecting our classification include largely geometric constructs such as the A and B Shannon ionic radii, the tolerance and octahedral factors, the A -O and B -O bond length, and the A and B Villars' Mendeleev numbers. We then construct an additional list of 625 A B O3 compounds assembled from charge conserving combinations of A and B atoms absent from our list of known compounds. Then, using the two ML models constructed on the known compounds, we predict that 235 of the 625 exist in a perovskite structure with a confidence greater than 50% and among them that 20 exist in the cubic structure (albeit, the latter with only ˜50 % confidence). We find that the new perovskites are most likely to occur when the A and B atoms are a lanthanide or actinide, when the A atom is an alkali, alkali earth, or late transition metal atom, or when the B atom is a p -block atom. We also compare the ML findings with the density functional theory calculations and convex hull analyses in the Open Quantum Materials Database (OQMD), which predicts the T =0 K ground-state stability of all the A B O3 compounds. We find that OQMD predicts 186 of 254 of the perovskites in the experimental database to be thermodynamically stable within 100 meV/atom of the convex hull and predicts 87 of the 235 ML-predicted perovskite compounds to be thermodynamically stable within 100 meV/atom of the convex hull, including 6 of these to

  16. Optically stimulated luminescence properties of Tm3+ doped KMgF3 fluoro perovskite

    International Nuclear Information System (INIS)

    Camargo, L.; Marcazzo, J.; Perez C, L.; Cruz Zaragoza, E.; Martinez O, S. A.

    2017-10-01

    In this work the optically stimulated luminescence (OSL) properties of undoped and Tm 3+ doped KMgF 3 fluoro perovskite have been investigated for the first time. OSL efficiency for stimulation with different wavelengths has been analyzed for each compound. The maximum OSL emission was found with blue light stimulation. The radioluminescence (Rl) spectra have shown two emission peaks at 455 and 360 nm, which can be ascribed to the 1 D 2 - 3 F 4 and 1 D 2 - 3 H 6 transitions of the Tm 3+ cations. It has been found that doping with Thulium 0.5 mol % renders the most intense OSL emission. Furthermore, several dosimetric properties such as OSL response as a function of dose, reproducibility of the OSL signal after several cycles of irradiation readout and the minimum detectable dose have been investigated. Finally, the OSL response of KMgF 3 : Tm 3+ has been compared to that of commercial Al 2 O 3 :C and the possible application of this fluoro perovskite to OSL dosimetry has been evaluated. (Author)

  17. First-principles analysis of ferroelectric transition in MnSnO3 and MnTiO3 perovskites

    Science.gov (United States)

    Kang, Sung Gu

    2018-06-01

    The ferroelectric instabilities of an artificially adopted Pnma structure in low tolerance perovskites have been explored (Kang et al., 2017) [4], where an unstable A-site environment was reported to be the major driving source for the low tolerance perovskites to exhibit ferroelectric instability. This study examined the ferroelectric transition of two magnetic perovskite materials, MnSnO3 and MnTiO3, in Pnma phase. Phase transitions to the Pnma phase at elevated pressures were observed. MnSnO3, which has a lower (larger) tolerance factor (B-site cation radius), showed a higher ferroelectric mode amplitude than MnTiO3. The distribution of the bond length of Mn-O and the mean quadratic elongation (QE) of octahedra (SnO6 or TiO6) were investigated for structural analysis. However, MnTiO3 showed a larger spontaneous polarization than MnSnO3 due to high Born effective charges of titanium. This study is useful because it provides a valuable pathway to the design of promising multiferroic materials.

  18. Fabrication and characterization of perovskite solar cells added with MnCl2, YCl3 or poly(methyl methacrylate)

    Science.gov (United States)

    Taguchi, Masaya; Suzuki, Atsushi; Tanaka, Hiroki; Oku, Takeo

    2018-01-01

    Perovskite-type CH3NH3PbI3-based photovoltaic devices were fabricated and characterized. Effects of manganese (Mn), yttrium (Y) compounds addition into the perovskite crystal on the photovoltaic properties were investigated. Also, the effects of poly(methyl methacrylate) (PMMA) addition on perovskite layer on the photovoltaic properties were investigated. When 3 % MnCl2 was added, the short circuit current density and conversion efficiency were improved by promoting the crystal growth of perovskite phase. The photoelectric conversion efficiency for 0.9 mg mL-1 PMMA added was 7.36 %. Open circuit voltage and fill factor were improved by 5 % YCl3 addition.

  19. Flexible All-Inorganic Perovskite CsPbBr3 Nonvolatile Memory Device.

    Science.gov (United States)

    Liu, Dongjue; Lin, Qiqi; Zang, Zhigang; Wang, Ming; Wangyang, Peihua; Tang, Xiaosheng; Zhou, Miao; Hu, Wei

    2017-02-22

    All-inorganic perovskite CsPbX 3 (X = Cl, Br, or I) is widely used in a variety of photoelectric devices such as solar cells, light-emitting diodes, lasers, and photodetectors. However, studies to understand the flexible CsPbX 3 electrical application are relatively scarce, mainly due to the limitations of the low-temperature fabricating process. In this study, all-inorganic perovskite CsPbBr 3 films were successfully fabricated at 75 °C through a two-step method. The highly crystallized films were first employed as a resistive switching layer in the Al/CsPbBr 3 /PEDOT:PSS/ITO/PET structure for flexible nonvolatile memory application. The resistive switching operations and endurance performance demonstrated the as-prepared flexible resistive random access memory devices possess reproducible and reliable memory characteristics. Electrical reliability and mechanical stability of the nonvolatile device were further tested by the robust current-voltage curves under different bending angles and consecutive flexing cycles. Moreover, a model of the formation and rupture of filaments through the CsPbBr 3 layer was proposed to explain the resistive switching effect. It is believed that this study will offer a new setting to understand and design all-inorganic perovskite materials for future stable flexible electronic devices.

  20. Mechanism of formation of perovskite phase and dielectric properties of Pb(Zn,Mg)1/3Nb2/3O3 ceramics prepared by columbite precursor routes

    International Nuclear Information System (INIS)

    Jang, H.M.; Cho, S.R.; Lee, K.M.

    1995-01-01

    The mechanism of formation of the perovskite phase and the dielectric properties of Pb(Zn,Mg) 1/3 Nb 2/3 O 3 (PZMN) ceramics were examined using two different types of columbite precursors, (Mg,Zn)Nb 2 O 6 (MZN) and MgNb 2 O 6 + ZnNb 2 O 6 (MN + ZN). The formation of perovskite phase in the PbO + MN + ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, due to the formation of pyrochlore phase of mixed divalent cations Pb 2-x (Zn,Mg) y Nb 2-y O 7-x-3y/2 , the pyrochlore/perovskite transformation in the PbO + MZN system proceeded uniformly with a spatial homogeneity. Further analysis suggested that the formation of perovskite phase is a diffusion-controlled process. The degree of diffuseness of the rhombohedral/cubic phase transition (DPT) is higher in the PbO + MN + ZN system than in the PbO + MZN specimen for T > T max (temperature of the dielectric permittivity maximum), indicating a broadened compositional distribution of the B-site cations in the PbO + MN + ZN system

  1. Efficient Lead-Free Solar Cells Based on Hollow {en}MASnI3 Perovskites.

    Science.gov (United States)

    Ke, Weijun; Stoumpos, Constantinos C; Spanopoulos, Ioannis; Mao, Lingling; Chen, Michelle; Wasielewski, Michael R; Kanatzidis, Mercouri G

    2017-10-18

    Tin-based perovskites have very comparable electronic properties to lead-based perovskites and are regarded as possible lower toxicity alternates for solar cell applications. However, the efficiency of tin-based perovskite solar cells is still low and they exhibit poor air stability. Here, we report lead-free tin-based solar cells with greatly enhanced performance and stability using so-called "hollow" ethylenediammonium and methylammonium tin iodide ({en}MASnI 3 ) perovskite as absorbers. Our results show that en can improve the film morphology and most importantly can serve as a new cation to be incorporated into the 3D MASnI 3 lattice. When the cation of en becomes part of the 3D structure, a high density of SnI 2 vacancies is created resulting in larger band gap, larger unit cell volume, lower trap-state density, and much longer carrier lifetime compared to classical MASnI 3 . The best-performing {en}MASnI 3 solar cell has achieved a high efficiency of 6.63% with an open circuit voltage of 428.67 mV, a short-circuit current density of 24.28 mA cm -2 , and a fill factor of 63.72%. Moreover, the {en}MASnI 3 device shows much better air stability than the neat MASnI 3 device. Comparable performance is also achieved for cesium tin iodide solar cells with en loading, demonstrating the broad scope of this approach.

  2. Tensile strain effect in ferroelectric perovskite oxide thin films on spinel magnesium aluminum oxide substrate

    Science.gov (United States)

    Zhou, Xiaolan

    Ferroelectrics are used in FeRAM (Ferroelectric random-access memory). Currently (Pb,Zr)TiO3 is the most common ferroelectric material. To get lead-free and high performance ferroelectric material, we investigated perovskite ferroelectric oxides (Ba,Sr)TiO3 and BiFeO3 films with strain. Compressive strain has been investigated intensively, but the effects of tensile strain on the perovskite films have yet to be explored. We have deposited (Ba,Sr)TiO3, BiFeO3 and related films by pulsed laser deposition (PLD) and analyzed the films by X-ray diffractometry (XRD), atomic force microscopy (AFM), etc. To obtain inherently fully strained films, the selection of the appropriate substrates is crucial. MgAl2O4 matches best with good quality and size, yet the spinel structure has an intrinsic incompatibility to that of perovskite. We introduced a rock-salt structure material (Ni 1-xAlxO1+delta) as a buffer layer to mediate the structural mismatch for (Ba,Sr)TiO3 films. With buffer layer Ni1-xAlxO1+delta, we show that the BST films have high quality crystallization and are coherently epitaxial. AFM images show that the films have smoother surfaces when including the buffer layer, indicating an inherent compatibility between BST-NAO and NAO-MAO. In-plane Ferroelectricity measurement shows double hysteresis loops, indicating an antiferroelectric-like behavior: pinned ferroelectric domains with antiparallel alignments of polarization. The Curie temperatures of the coherent fully strained BST films are also measured. It is higher than 900°C, at least 800°C higher than that of bulk. The improved Curie temperature makes the use of BST as FeRAM feasible. We found that the special behaviors of ferroelectricity including hysteresis loop and Curie temperature are due to inherent fully tensile strain. This might be a clue of physics inside ferroelectric stain engineering. An out-of-plane ferroelectricity measurement would provide a full whole story of the tensile strain. However, a

  3. Photovoltaic Effect of 2D Homologous Perovskites

    International Nuclear Information System (INIS)

    Jung, Mi-Hee

    2017-01-01

    Highlights: • The mixed perovskite was prepared by exposure of MAI gas on the BAPbI_4 film. • The increased dimensional perovskite shows a smaller band gap than 2D perovskite. • The mixed perovskite system shows the vertical crystal orientation. • The mixed perovskite cell exhibits the higher Jsc and FF than 2D perovskite cell. - Abstract: The controlled growth of mixed dimensional perovskite structures, (C_6H_5CH_2NH_2)(CH_3NH_3)_n_-_1Pb_nI_3_n_+_1, through the introduction of CH_3NH_3I molecule vapor into the two-dimensional perovskite C_6H_5CH_2NH_3PbI_4 structure and its application in photovoltaic devices is reported. The dimensionality of (C_6H_5CH_2NH_2)(CH_3NH_3)_n_-_1Pb_nI_3_n_+_1 is controlled using the exposure time to the CH_3NH_3I vapor on the C_6H_5CH_2NH_3PbI_4 perovskite film. As the stacking of the lead iodide lattice increases, the crystallographic planes of the inorganic perovskite compound exhibit vertical growth in order to facilitate efficient charge transport. Furthermore, the devices have a smaller band gap, which offers broader absorption and the potential to increase the photocurrent density in the solar cell. As a result, the photovoltaic device based on the (C_6H_5CH_2NH_2)(CH_3NH_3)_n_-_1Pb_nI_3_n_+_1 perovskite exhibits a power conversion efficiency of 5.43% with a short circuit current density of 14.49 mA cm"−"2, an open circuit voltage of 0.85 V, and a fill factor of 44.30 for the best power conversion efficiency under AM 1.5G solar irradiation (100 mW cm"−"2), which is significantly higher than the 0.34% of the pure two-dimensional BAPbI_4 perovskite-based solar cell.

  4. Novel Solvent-free Perovskite Deposition in Fabrication of Normal and Inverted Architectures of Perovskite Solar Cells

    Science.gov (United States)

    Nejand, Bahram Abdollahi; Gharibzadeh, Saba; Ahmadi, Vahid; Shahverdi, H. Reza

    2016-01-01

    We introduced a new approach to deposit perovskite layer with no need for dissolving perovskite precursors. Deposition of Solution-free perovskite (SFP) layer is a key method for deposition of perovskite layer on the hole or electron transport layers that are strongly sensitive to perovskite precursors. Using deposition of SFP layer in the perovskite solar cells would extend possibility of using many electron and hole transport materials in both normal and invert architectures of perovskite solar cells. In the present work, we synthesized crystalline perovskite powder followed by successful deposition on TiO2 and cuprous iodide as the non-sensitve and sensitive charge transport layers to PbI2 and CH3NH3I solution in DMF. The post compressing step enhanced the efficiency of the devices by increasing the interface area between perovskite and charge transport layers. The 9.07% and 7.71% cell efficiencies of the device prepared by SFP layer was achieved in respective normal (using TiO2 as a deposition substrate) and inverted structure (using CuI as deposition substrate) of perovskite solar cell. This method can be efficient in large-scale and low cost fabrication of new generation perovskite solar cells. PMID:27640991

  5. Influence of the Preparation Method on Planar Perovskite CH3NH3PbI3-xClx Solar Cell Performance and Hysteresis

    Science.gov (United States)

    Ivanova, A.; Tokmakov, A.; Lebedeva, K.; Roze, M.; Kaulachs, I.

    2017-08-01

    Organometal halide perovskites are promising materials for lowcost, high-efficiency solar cells. The method of perovskite layer deposition and the interfacial layers play an important role in determining the efficiency of perovskite solar cells (PSCs). In the paper, we demonstrate inverted planar perovskite solar cells where perovskite layers are deposited by two-step modified interdiffusion and one-step methods. We also demonstrate how PSC parameters change by doping of charge transport layers (CTL). We used dimethylsupoxide (DMSO) as dopant for the hole transport layer (PEDOT:PSS) but for the electron transport layer [6,6]-phenyl C61 butyric acid methyl ester (PCBM)) we used N,N-dimethyl-N-octadecyl(3-aminopropyl)trimethoxysilyl chloride (DMOAP). The highest main PSC parameters (PCE, EQE, VOC) were obtained for cells prepared by the one-step method with fast crystallization and doped CTLs but higher fill factor (FF) and shunt resistance (Rsh) values were obtained for cells prepared by the two-step method with undoped CTLs.

  6. Crystallographic Investigations into Properties of Acentric Hybrid Perovskite Single Crystals NH(CH3)3SnX3(X = Cl, Br)

    KAUST Repository

    Dang, Yangyang

    2016-10-11

    The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (no. 9) and NH(CH3)3SnBr3 belongs to the orthorhombic space group Pna21 (no. 33) by DSC, single-crystal X-ray diffraction and temperature-dependent SHG measurements, which clarify the former results. These results should pave the way for further studies of these materials in optoelectronics.

  7. Thin-Film Transformation of NH4 PbI3 to CH3 NH3 PbI3 Perovskite: A Methylamine-Induced Conversion-Healing Process.

    Science.gov (United States)

    Zong, Yingxia; Zhou, Yuanyuan; Ju, Minggang; Garces, Hector F; Krause, Amanda R; Ji, Fuxiang; Cui, Guanglei; Zeng, Xiao Cheng; Padture, Nitin P; Pang, Shuping

    2016-11-14

    Methylamine-induced thin-film transformation at room-temperature is discovered, where a porous, rough, polycrystalline NH 4 PbI 3 non-perovskite thin film converts stepwise into a dense, ultrasmooth, textured CH 3 NH 3 PbI 3 perovskite thin film. Owing to the beneficial phase/structural development of the thin film, its photovoltaic properties undergo dramatic enhancement during this NH 4 PbI 3 -to-CH 3 NH 3 PbI 3 transformation process. The chemical origins of this transformation are studied at various length scales. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. CH3 NH3 PbI3 and HC(NH2 )2 PbI3 Powders Synthesized from Low-Grade PbI2 : Single Precursor for High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Zhang, Yong; Kim, Seul-Gi; Lee, Do-Kyoung; Park, Nam-Gyu

    2018-05-09

    High-efficiency perovskite solar cells are generally fabricated by using highly pure (>99.99 %) PbI 2 mixed with an organic iodide in polar aprotic solvents. However, the use of such an expensive chemical may impede progress toward large-scale industrial applications. Here, we report on the synthesis of perovskite powders by using inexpensive low-grade (99 %) PbI 2 and on the photovoltaic performance of perovskite solar cells prepared from a powder-based single precursor. Pure APbI 3 [A=methylammonium (MA) or formamidinium (FA)] perovskite powders were synthesized by treating low-grade PbI 2 with MAI or FAI in acetonitrile at ambient temperature. The structural phase purity was confirmed by X-ray diffraction. The solar cell with a MAPbI 3 film prepared from the synthesized perovskite powder demonstrated a power conversion efficiency (PCE) of 17.14 %, which is higher than the PCE of MAPbI 3 films prepared by using both MAI and PbI 2 as precursors (PCE=13.09 % for 99 % pure PbI 2 and PCE=16.39 % for 99.9985 % pure PbI 2 ). The synthesized powder showed better absorption and photoluminescence, which were responsible for the better photovoltaic performance. For the FAPbI 3 powder, a solution with a yellow non-perovskite δ-FAPbI 3 powder synthesized at room temperature was found to lead to a black perovskite film, whereas a solution with the black perovskite α-FAPbI 3 powder synthesized at 150 °C was not transformed into a black perovskite film. The α↔δ transition between the powder and film was assumed to correlate with the difference in the iodoplumbates in the powder-dissolved solution. An average PCE of 17.21 % along with a smaller hysteresis [ΔPCE=PCE reverse -PCE forward )=1.53 %] was demonstrated from the perovskite solar cell prepared by using δ-FAPbI 3 powder; this PCE is higher than the average PCE of 17.05 % with a larger hysteresis (ΔPCE=2.71 %) for a device based on a conventional precursor solution dissolving MAI with high

  9. LaFePdO3 perovskite automotive catalyst having a self-regenerative function

    International Nuclear Information System (INIS)

    Tanaka, Hirohisa; Tan, Isao; Uenishi, Mari; Taniguchi, Masashi; Kimura, Mareo; Nishihata, Yasuo; Mizuki, Jun'ichiro

    2006-01-01

    An automotive gasoline engine is operated close to the stoichiometric air-to-fuel ratio to convert the pollutant emissions simultaneously, accompanying with redox (reduction and oxidation) fluctuations in exhaust-gas composition through adjusting the air-to-fuel ratio. An innovative LaFe 0.95 Pd 0.05 O 3 perovskite catalyst, named 'the intelligent catalyst', has been developed, and which has a new self-regenerative function of the precious metal in the inherent fluctuations of automotive exhaust-gas. The LaFe 0.95 Pd 0.05 O 3 perovskite catalyst, La located at the A-site, was prepared by the alkoxide method. Pd located at the B-site of the perovskite lattice in the oxidative atmosphere, and segregated out to form small metallic particles in the reductive atmosphere. The catalyst retained a predominantly perovskite structure throughout a redox cycle of the exhaust-gas, while the local structure around Pd could be changed in a completely reversible manner. The agglomeration and growth of Pd particles is suppressed, even under the severe environment, as a result of the movement between inside and outside the perovskite lattice. It is revealed that the self-regenerative function of Pd occurs even at 200 deg. C, unexpectedly low temperature, in the LaFe 0.95 Pd 0.05 O 3 catalyst. Since the high catalytic activity is maintained, the great reduction of Pd loading has been achieved. The intelligent catalyst is expected as a new application of the rare earth, and then the technology is expected in the same way in the global standard of the catalyst designing

  10. Hybrid Perovskite/Perovskite Heterojunction Solar Cells.

    Science.gov (United States)

    Hu, Yinghong; Schlipf, Johannes; Wussler, Michael; Petrus, Michiel L; Jaegermann, Wolfram; Bein, Thomas; Müller-Buschbaum, Peter; Docampo, Pablo

    2016-06-28

    Recently developed organic-inorganic hybrid perovskite solar cells combine low-cost fabrication and high power conversion efficiency. Advances in perovskite film optimization have led to an outstanding power conversion efficiency of more than 20%. Looking forward, shifting the focus toward new device architectures holds great potential to induce the next leap in device performance. Here, we demonstrate a perovskite/perovskite heterojunction solar cell. We developed a facile solution-based cation infiltration process to deposit layered perovskite (LPK) structures onto methylammonium lead iodide (MAPI) films. Grazing-incidence wide-angle X-ray scattering experiments were performed to gain insights into the crystallite orientation and the formation process of the perovskite bilayer. Our results show that the self-assembly of the LPK layer on top of an intact MAPI layer is accompanied by a reorganization of the perovskite interface. This leads to an enhancement of the open-circuit voltage and power conversion efficiency due to reduced recombination losses, as well as improved moisture stability in the resulting photovoltaic devices.

  11. First-principles study of structural stability and elastic property of pre-perovskite PbTiO3

    International Nuclear Information System (INIS)

    Liu Yong; Ni Li-Hong; Ren Zhao-Hui; Xu Gang; Li Xiang; Song Chen-Lu; Han Gao-Rong

    2012-01-01

    The structural stability and the elastic properties of a novel structure of lead titanate, which is named pre- perovskite PbTiO 3 (PP-PTO) and is constructed with TiO 6 octahedral columns arranged in a one-dimensional manner, are investigated by using first-principles calculations. PP-PTO is energetically unstable compared with conventional perovskite phases, however it is mechanically stable. The equilibrium transition pressures for changing from pre- perovskite to cubic and tetragonal phases are −0.5 GPa and −1.4 GPa, respectively, with first-order characteristics. Further, the differences in elastic properties between pre-perovskite and conventional perovskite phases are discussed for the covalent bonding network, which shows a highly anisotropic character in PP-PTO. This study provides a crucial insight into the structural stabilities of PP-PTO and conventional perovskite. (condensed matter: structural, mechanical, and thermal properties)

  12. Transport, Optical, and Magnetic Properties of the Conducting Halide Perovskite CH 3NH 3SnI 3

    Science.gov (United States)

    Mitzi, D. B.; Feild, C. A.; Schlesinger, Z.; Laibowitz, R. B.

    1995-01-01

    A low-temperature ( T ≤ 100°C) solution technique is described for the preparation of polycrystalline and single crystal samples of the conducting halide perovskite, CH 3NH 3SnI 3. Transport, Hall effect, magnetic, and optical properties are examined over the temperature range 1.8-300 K, confirming that this unusual conducting halide perovskite is a low carrier density p-type metal with a Hall hole density, 1/ RHe ≃ 2 × 10 19 cm -3. The resistivity of pressed pellet samples decreases with decreasing temperature with resistivity ratio ρ(300 K)/ρ(2 K) ≃ 3 and room temperature resistivity ρ(300 K) ≃ 7 mΩ-cm. A free-carrier infrared reflectivity spectrum with a plasma edge observed at approximately 1600 cm -1 further attests to the metallic nature of this compound and suggests a small optical effective mass, m* ≃ 0.2.

  13. Modeling defects and plasticity in MgSiO3 post-perovskite: Part 1-generalized stacking faults.

    Science.gov (United States)

    Goryaeva, Alexandra M; Carrez, Philippe; Cordier, Patrick

    In this work, we examine the transferability of a pairwise potential model (derived for MgSiO 3 perovskite) to accurately compute the excess energies of the generalized stacking faults (GSF, also called γ -surfaces) in MgSiO 3 post-perovskite. All calculations have been performed at 120 GPa, a pressure relevant to the D″ layer. Taking into account an important aspect of crystal chemistry for complex materials, we consider in detail all possible locations of slip planes in the post-perovskite structure. The γ -surface calculations emphasize the easiness of glide of slip systems with the smallest shear vector [100] and of the [001](010) slip system. Our results are in agreement with previous ab initio calculations. This validates the use the chosen potential model for further full atomistic modeling of dislocations in MgSiO 3 post-perovskite.

  14. Low temperature synthesis and photocatalytic property of perovskite-type LaCoO{sub 3} hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shasha [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Niu, Helin, E-mail: niuhelin@ahu.edu.cn [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Tao, Zhiyin; Song, Jiming; Mao, Changjie; Zhang, Shengyi [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Chen, Changle, E-mail: changle@ustc.edu.cn [CAS Key Laboratory of Soft Matter Chemistry and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Wang, Dong [Department of Bio-Health Technology, College of Biomedical Science, Kangwon National University, Chuncheon, Gangwon-Do 200-701 (Korea, Republic of)

    2013-11-05

    Highlights: •Hollow perovskite-type LaCoO{sub 3} is fabricated by green colloidal template method. •Carbonaceous colloids acted as templates and offered internal heat source. •The calcination temperature to form perovskite-type LaCoO{sub 3} was dropped to 550 °C. •The photocatalytic properties were studied upon UV irradiation. •Hollow perovskite-type LaCoO{sub 3} shows excellent photocatalytic activity on dyes. -- Abstract: Hollow perovskite-type LaCoO{sub 3} was successfully fabricated by surface-ion adsorption method utilizing the carbonaceous colloids as template under relatively low calcination temperature. Carbonaceous colloids not only acted as templates but also offered internal heat source during calcination process. The impact of calcined temperature and time on the structure and morphology of the product were studied and the possible formation process of perovskite-type LaCoO{sub 3} hollow spheres was illustrated. The obtained product was characterized by SEM, TEM, XRD, TG-DSC, ICP-OES, BET and UV–visible absorption spectra. The photocatalytic activities for degradation of methylene blue, methyl orange and neutral red were tested. The good photocatalytic degradation activity of the three different dyes and the band gap of 2.07 eV make it a promising candidate material for photocatalytic applications.

  15. Effect of Oblique-Angle Sputtered ITO Electrode in MAPbI3 Perovskite Solar Cell Structures.

    Science.gov (United States)

    Lee, Kun-Yi; Chen, Lung-Chien; Wu, Yu-June

    2017-10-03

    This investigation reports on the characteristics of MAPbI 3 perovskite films on obliquely sputtered ITO/glass substrates that are fabricated with various sputtering times and sputtering angles. The grain size of a MAPbI 3 perovskite film increases with the oblique sputtering angle of ITO thin films from 0° to 80°, indicating that the surface properties of the ITO affect the wettability of the PEDOT:PSS thin film and thereby dominates the number of perovskite nucleation sites. The optimal power conversion efficiency (Eff) is achieved 11.3% in a cell with an oblique ITO layer that was prepared using a sputtering angle of 30° for a sputtering time of 15 min.

  16. The Recombination Mechanism and True Green Amplified Spontaneous Emission in CH3NH3PbBr3 Perovskite

    KAUST Repository

    Priante, Davide

    2015-01-01

    . M. Bakr, and B. S. Ooi, "The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites", Applied Physics Letters, 106, 081902, 2015. DOI: 10.1063/1.4913463

  17. Planar structured perovskite solar cells by hybrid physical chemical vapor deposition with optimized perovskite film thickness

    Science.gov (United States)

    Wei, Xiangyang; Peng, Yanke; Jing, Gaoshan; Cui, Tianhong

    2018-05-01

    The thickness of perovskite absorber layer is a critical parameter to determine a planar structured perovskite solar cell’s performance. By modifying the spin coating speed and PbI2/N,N-dimethylformamide (DMF) solution concentration, the thickness of perovskite absorber layer was optimized to obtain high-performance solar cells. Using a PbI2/DMF solution of 1.3 mol/L, maximum power conversion efficiency (PCE) of a perovskite solar cell is 15.5% with a perovskite film of 413 nm at 5000 rpm, and PCE of 14.3% was also obtained for a solar cell with a perovskite film of 182 nm thick. It is derived that higher concentration of PbI2/DMF will result in better perovskite solar cells. Additionally, these perovskite solar cells are highly uniform. In 14 sets of solar cells, standard deviations of 11 sets of solar cells were less than 0.50% and the smallest standard deviation was 0.25%, which demonstrates the reliability and effectiveness of hybrid physical chemical vapor deposition (HPCVD) method.

  18. Hierarchically porous LaFeO3 perovskite prepared from the pomelo peel bio-template for catalytic oxidation of NO

    Science.gov (United States)

    Zhao, Shaojun; Wang, Li; Wang, Ying; Li, Xing

    2018-05-01

    In this paper, pomelo peel was used as biological template to obtain hierarchically porous LaFeO3 perovskite for the catalytic oxidation of NO to NO2. In addition, X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption analyses, X-ray photoelectron spectra (XPS), NO temperature-programmed desorption (NO-TPD), oxygen temperature-programmed desorption (O2-TPD) and hydrogen temperature-programmed reduction (H2-TPR) were used to investigate the micro-structure and the redox properties of the hierarchically porous LaFeO3 perovskite prepared from pomelo peel biological template and the LaFeO3 perovskite without the biological template. The results indicated that the hierarchically porous LaFeO3 perovskite successfully replicated the porous structure of pomelo peel with high specific surface area. Compared to the LaFeO3 perovskite prepared without the pomelo peel template, the hierarchically porous LaFeO3 perovskite showed better catalytic oxidization of NO to NO2 under the same conditions. The maximum NO conversions for LaFeO3 prepared with and without template were 90% at 305 °C and 76% at 313 °C, respectively. This is mainly attributed to the higher ratio of Fe4+/Fe3+, the hierarchically porous structure with more adsorbed oxygen species and higher surface area for the hierarchically porous LaFeO3 perovskite compared with the sample prepared without the pomelo peel template.

  19. Optical constants of CH3NH3PbBr3 perovskite thin films measured by spectroscopic ellipsometry

    KAUST Repository

    Alias, Mohd Sharizal; Dursun, Ibrahim; Saidaminov, Makhsud I.; Diallo, Elhadj Marwane; Mishra, Pawan; Ng, Tien Khee; Bakr, Osman; Ooi, Boon S.

    2016-01-01

    function) of CH3NH3PbBr3 perovskite thin films using spectroscopic ellipsometry. Due to the existence of voids, the refractive index of the thin films is around 8% less than the single crystals counterpart. The energy bandgap is around 2.309 eV as obtained

  20. Structural chemistry and magnetic properties of the perovskite Sr{sub 3}Fe{sub 2}TeO{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yawei; Hunter, Emily C. [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Battle, Peter D., E-mail: peter.battle@chem.ox.ac.uk [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Sena, Robert Paria; Hadermann, Joke [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234 (Australia); Cadogan, J.M. [School of Physical, Environmental and Mathematical Sciences, UNSW Canberra at the Australian Defence Force Academy, Canberra BC 2610 (Australia)

    2016-10-15

    A polycrystalline sample of perovskite-like Sr{sub 3}Fe{sub 2}TeO{sub 9} has been prepared in a solid-state reaction and studied by a combination of electron microscopy, Mössbauer spectroscopy, magnetometry, X-ray diffraction and neutron diffraction. The majority of the reaction product is shown to be a trigonal phase with a 2:1 ordered arrangement of Fe{sup 3+} and Te{sup 6+} cations. However, the sample is prone to nano-twinning and tetragonal domains with a different pattern of cation ordering exist within many crystallites. Antiferromagnetic ordering exists in the trigonal phase at 300 K and Sr{sub 3}Fe{sub 2}TeO{sub 9} is thus the first example of a perovskite with 2:1 trigonal cation ordering to show long-range magnetic order. At 300 K the antiferromagnetic phase coexists with two paramagnetic phases which show spin-glass behaviour below ~80 K. - Graphical abstract: Sr{sub 3}Fe{sub 2}TeO{sub 9} has a 2:1 ordered arrangement of Fe{sup 3+} and Te{sup 6+} cations over the octahedral sites of a perovskite structure and is antiferromagnetic at room temperature. - Highlights: • 2:1 Cation ordering in a trigonal perovskite. • Magnetically ordered trigonal perovskite. • Intergrowth of nanodomains in perovskite microstructure.

  1. Overcoming Short-Circuit in Lead-Free CH3NH3SnI3 Perovskite Solar Cells via Kinetically Controlled Gas-Solid Reaction Film Fabrication Process.

    Science.gov (United States)

    Yokoyama, Takamichi; Cao, Duyen H; Stoumpos, Constantinos C; Song, Tze-Bin; Sato, Yoshiharu; Aramaki, Shinji; Kanatzidis, Mercouri G

    2016-03-03

    The development of Sn-based perovskite solar cells has been challenging because devices often show short-circuit behavior due to poor morphologies and undesired electrical properties of the thin films. A low-temperature vapor-assisted solution process (LT-VASP) has been employed as a novel kinetically controlled gas-solid reaction film fabrication method to prepare lead-free CH3NH3SnI3 thin films. We show that the solid SnI2 substrate temperature is the key parameter in achieving perovskite films with high surface coverage and excellent uniformity. The resulting high-quality CH3NH3SnI3 films allow the successful fabrication of solar cells with drastically improved reproducibility, reaching an efficiency of 1.86%. Furthermore, our Kelvin probe studies show the VASP films have a doping level lower than that of films prepared from the conventional one-step method, effectively lowering the film conductivity. Above all, with (LT)-VASP, the short-circuit behavior often obtained from the conventional one-step-fabricated Sn-based perovskite devices has been overcome. This study facilitates the path to more successful Sn-perovskite photovoltaic research.

  2. Phase Engineering of Perovskite Materials for High-Efficiency Solar Cells: Rapid Conversion of CH3NH3PbI3 to Phase-Pure CH3NH3PbCl3 via Hydrochloric Acid Vapor Annealing Post-Treatment.

    Science.gov (United States)

    Zhou, Weiran; Zhou, Pengcheng; Lei, Xunyong; Fang, Zhimin; Zhang, Mengmeng; Liu, Qing; Chen, Tao; Zeng, Hualing; Ding, Liming; Zhu, Jun; Dai, Songyuan; Yang, Shangfeng

    2018-01-17

    Organometal halide CH 3 NH 3 PbI 3 (MAPbI 3 ) has been commonly used as the light absorber layer of perovskite solar cells (PSCs), and, especially, another halide element chlorine (Cl) has been often incorporated to assist the crystallization of perovskite film. However, in most cases, a predominant MAPbI 3 phase with trace of Cl - is obtained ultimately and the role of Cl involvement remains unclear. Herein, we develop a low-cost and facile method, named hydrochloric acid vapor annealing (HAVA) post-treatment, and realize a rapid conversion of MAPbI 3 to phase-pure MAPbCl 3 , demonstrating a new concept of phase engineering of perovskite materials toward efficiency enhancement of PSCs for the first time. The average grain size of perovskite film after HAVA post-treatment increases remarkably through an Ostwald ripening process, leading to a denser and smoother perovskite film with reduced trap states and enhanced crystallinity. More importantly, the generation of MAPbCl 3 secondary phase via phase engineering is beneficial for improving the carrier mobility with a more balanced carrier transport rate and enlarging the band gap of perovskite film along with optimized energy level alignment. As a result, under the optimized HAVA post-treatment time (2 min), we achieved a significant enhancement of the power conversion efficiency (PCE) of the MAPbI 3 -based planar heterojunction-PSC device from 14.02 to 17.40% (the highest PCE reaches 18.45%) with greatly suppressed hysteresis of the current-voltage response.

  3. Highly efficient perovskite solar cells based on a nanostructured WO3-TiO2 core-shell electron transporting material

    KAUST Repository

    Mahmood, Khalid; Swain, Bhabani Sankar; Kirmani, Ahmad R.; Amassian, Aram

    2015-01-01

    Until recently, only mesoporous TiO2 and ZnO were successfully demonstrated as electron transport layers (ETL) alongside the reports of ZrO2 and Al2O3 as scaffold materials in organometal halide perovskite solar cells, largely owing to ease of processing and to high power conversion efficiency. In this article, we explore tungsten trioxide (WO3)-based nanostructured and porous ETL materials directly grown hydrothermally with different morphologies such as nanoparticles, nanorods and nanosheet arrays. The nanostructure morphology strongly influences the photocurrent and efficiency in organometal halide perovskite solar cells. We find that the perovskite solar cells based on WO3 nanosheet arrays yield significantly enhanced photovoltaic performance as compared to nanoparticles and nanorod arrays due to good perovskite absorber infiltration in the porous scaffold and more rapid carrier transport. We further demonstrate that treating the WO3 nanostructures with an aqueous solution of TiCl4 reduces charge recombination at the perovskite/WO3 interface, resulting in the highest power conversion efficiency of 11.24% for devices based on WO3 nanosheet arrays. The successful demonstration of alternative ETL materials and nanostructures based on WO3 will open up new opportunities in the development of highly efficient perovskite solar cells. This journal is © The Royal Society of Chemistry 2015.

  4. Phase Stability and Electronic Structure of Prospective Sb-Based Mixed Sulfide and Iodide 3D Perovskite (CH3NH3)SbSI2.

    Science.gov (United States)

    Li, Tianyang; Wang, Xiaoming; Yan, Yanfa; Mitzi, David B

    2018-06-29

    Lead-free antimony-based mixed sulfide and iodide perovskite phases have recently been reported to be synthesized experimentally and to exhibit reasonable photovoltaic performance. Through a combination of experimental validation and computational analysis, we show no evidence of the formation of the mixed sulfide and iodide perovskite phase, MASbSI 2 (MA = CH 3 NH 3 + ), and instead that the main products are a mixture of the binary and ternary compounds (Sb 2 S 3 and MA 3 Sb 2 I 9 ). Density functional theory calculations also indicate that such a mixed sulfide and iodide perovskite phase should be thermodynamically less stable compared with binary/ternary anion-segregated secondary phases and less likely to be synthesized under equilibrium conditions. Additionally, band structure calculations show that this mixed sulfide and iodide phase, if possible to synthesize (e.g., under nonequilibrium conditions), should have a suitable direct band gap for photovoltaic application.

  5. Perovskite Solar Cell

    Indian Academy of Sciences (India)

    Organic–inorganic halide perovskite, a newcomerin the solar cell industry has proved its potential forincreasing efficiency rapidly from 3.8% in 2009 to 22.1% in2016. High efficiency, flexibility, and cell architecture of theemerging hybrid halide perovskite have caught the attentionof researchers and technologists in the field.

  6. [(CH3)3NCH2CH2NH3]SnI4: a layered perovskite with quaternary/primary ammonium dications and short interlayer iodine-iodine contacts.

    Science.gov (United States)

    Xu, Zhengtao; Mitzi, David B; Medeiros, David R

    2003-03-10

    The organic-inorganic hybrid [(CH(3))(3)NCH(2)CH(2)NH(3)]SnI(4) presents a layered perovskite structure, templated by an organic dication containing both a primary and a quaternary ammonium group. Due to the high charge density and small size of the organic cation, the separation of the perovskite layers is small and short iodine-iodine contacts of 4.19 A are formed between the layers. Optical thin-film measurements on this compound indicate a significant red shift of the exciton peak (630 nm) associated with the band gap, as compared with other SnI(4)(2)(-)-based layered perovskite structures.

  7. Photon Reabsorption in Mixed CsPbCl3:CsPbI3 Perovskite Nanocrystal Films for Light-Emitting Diodes

    KAUST Repository

    Davis, Nathaniel J. L. K.

    2017-01-24

    Cesium lead halide nanocrystals, CsPbX3 (X = Cl, Br, I), exhibit photoluminescence quantum efficiencies approaching 100% without the core–shell structures usually used in conventional semiconductor nanocrystals. These high photoluminescence efficiencies make these crystals ideal candidates for light-emitting diodes (LEDs). However, because of the large surface area to volume ratio, halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, which is one of the limiting factors for white-light applications requiring a mixture of different crystal compositions to achieve a broad emission spectrum. Here, we use mixtures of chloride and iodide CsPbX3 (X = Cl, I) perovskite nanocrystals where anion exchange is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a poly(methyl methacrylate) matrix via photon reabsorption, which also occurs in electrically excited crystals in bulk heterojunction LEDs.

  8. Photovoltaic performance of textured silicon solar cells with MAPbBr3 perovskite nanophosphors to induce luminescent down-shifting

    Science.gov (United States)

    Ho, Wen-Jeng; Li, Guan-Yi; Liu, Jheng-Jie; Lin, Zong-Xian; You, Bang-Jin; Ho, Chun-Hung

    2018-04-01

    This study employed a two-step multi-cycle spin-coating method for the application of MAPbBr3 perovskite nanophosphors on textured silicon solar cells with the aim of enhancing photovoltaic performance through luminescent down-shifting (LDS). The surface morphology and dimensions of the MAPbBr3 perovskite nanophosphors were examined using scanning electron microscopy in conjunction with ImageJ software. The LDS effects of the nanophosphors were revealed by measuring photo-luminance, optical reflectance, and external quantum efficiency. The photovoltaic performance of cells with and without MAPbBr3 perovskite nanophosphors was evaluated according to photovoltaic current density-voltage (J-V) under AM 1.5 G solar illumination. Compared to uncoated cells, two-layer and one-layer coatings of MAPbBr3 perovskite nanophosphors were shown to enhance conversion efficiency by 4.56% and 3.38%, respectively.

  9. Room-Temperature Atomic Layer Deposition of Al2 O3 : Impact on Efficiency, Stability and Surface Properties in Perovskite Solar Cells.

    Science.gov (United States)

    Kot, Malgorzata; Das, Chittaranjan; Wang, Zhiping; Henkel, Karsten; Rouissi, Zied; Wojciechowski, Konrad; Snaith, Henry J; Schmeisser, Dieter

    2016-12-20

    In this work, solar cells with a freshly made CH 3 NH 3 PbI 3 perovskite film showed a power conversion efficiency (PCE) of 15.4 % whereas the one with 50 days aged perovskite film only 6.1 %. However, when the aged perovskite was covered with a layer of Al 2 O 3 deposited by atomic layer deposition (ALD) at room temperature (RT), the PCE value was clearly enhanced. X-ray photoelectron spectroscopy study showed that the ALD precursors are chemically active only at the perovskite surface and passivate it. Moreover, the RT-ALD-Al 2 O 3 -covered perovskite films showed enhanced ambient air stability. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Green perovskite light emitting diodes based on the ITO/Al2O3/CsPbBr3 heterojunction structure

    Science.gov (United States)

    Zhuang, Shiwei; Ma, Xue; Hu, Daqiang; Dong, Xin; Zhang, Yuantao; Zhang, Baolin

    2018-03-01

    Perovskite light emitting diodes (PeLEDs) now emerge as a promising new optoelectronic application field for these amazing semiconductors. For the purpose of investigating the device structures and light emission mechanisms of PeLEDs, we have fabricated green PeLEDs based on the ITO/Al2O3/CsPbBr3 heterojunction structure. The emission layer inorganic perovskite CsPbBr3 film with small grain sizes (∼28.9 nm) was prepared using a two-step method. The device exhibits a typical rectification behavior with turn-on voltage of ∼6 V. The EL emission band is narrow with the FWHM of ∼25 nm. The peak EQE of the device was ∼0.09%. The working mechanism of the device is also discussed. The result of the present work provides a feasible innovation idea of PeLEDs fabrication and great potentials for the development of perovskite based LEDs.

  11. Formation enthalpies of LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Jianqi [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610064 (China); Guo, Xiaofeng [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Mielewczyk-Gryn, Aleksandra [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States); Faculty of Applied Physics and Mathematics, Department of Solid State Physics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California, Davis, CA 95616 (United States)

    2015-07-15

    High-temperature oxide melt solution calorimetry using 3Na{sub 2}O·MoO{sub 3} at 802 °C was performed for interlanthanide perovskites LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Tm{sub 2}O{sub 3} and Yb{sub 2}O{sub 3}). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be −8.3±3.4 kJ/mol for LaHoO{sub 3}, −9.9±3.0 kJ/mol for LaErO{sub 3}, −10.8±2.7 kJ/mol for LaTmO{sub 3} and −12.3±2.9 kJ/mol for LaYbO{sub 3}. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds. - Graphical abstract: A linear relationship between the enthalpy of formation and the tolerance factor for interlanthanide LaLn'O{sub 3} (Ln'=Ho, Er, Tm, and Yb) and other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites. - Highlights: • Interlanthanide perovskites were synthesized by solid state reactions. • Their enthalpies of formation were measured by oxide melt solution calorimetry. • ΔH{sub f,ox} shows a linear relationship with tolerance factor.

  12. Dual-Function Au@Y2O3:Eu3+ Smart Film for Enhanced Power Conversion Efficiency and Long-Term Stability of Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Chang Woo; Eom, Tae Young; Yang, In Seok; Kim, Byung Su; Lee, Wan In; Kang, Yong Soo; Kang, Young Soo

    2017-07-28

    In the present study, a dual-functional smart film combining the effects of wavelength conversion and amplification of the converted wave by the localized surface plasmon resonance has been investigated for a perovskite solar cell. This dual-functional film, composed of Au nanoparticles coated on the surface of Y 2 O 3 :Eu 3+ phosphor (Au@Y 2 O 3 :Eu 3+ ) nanoparticle monolayer, enhances the solar energy conversion efficiency to electrical energy and long-term stability of photovoltaic cells. Coupling between the Y 2 O 3 :Eu 3+ phosphor monolayer and ultraviolet solar light induces the latter to be converted into visible light with a quantum yield above 80%. Concurrently, the Au nanoparticle monolayer on the phosphor nanoparticle monolayer amplifies the converted visible light by up to 170%. This synergy leads to an increased solar light energy conversion efficiency of perovskite solar cells. Simultaneously, the dual-function film suppresses the photodegradation of perovskite by UV light, resulting in long-term stability. Introducing the hybrid smart Au@Y 2 O 3 :Eu 3+ film in perovskite solar cells increases their overall solar-to-electrical energy conversion efficiency to 16.1% and enhances long-term stability, as compared to the value of 15.2% for standard perovskite solar cells. The synergism between the wavelength conversion effect of the phosphor nanoparticle monolayer and the wave amplification by the localized surface plasmon resonance of the Au nanoparticle monolayer in a perovskite solar cell is comparatively investigated, providing a viable strategy of broadening the solar spectrum utilization.

  13. Two-Photon Absorption in Organometallic Bromide Perovskites

    KAUST Repository

    Walters, Grant

    2015-07-21

    Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

  14. Two-Photon Absorption in Organometallic Bromide Perovskites

    KAUST Repository

    Walters, Grant; Sutherland, Brandon R; Hoogland, Sjoerd; Shi, Dong; Comin, Riccardo; Sellan, Daniel P.; Bakr, Osman; Sargent, Edward H.

    2015-01-01

    Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

  15. Chemical Substitution-Induced and Competitive Formation of 6H and 3C Perovskite Structures in Ba3-xSrxZnSb2O9: The Coexistence of Two Perovskites in 0.3 ≤ x ≤ 1.0.

    Science.gov (United States)

    Li, Jing; Jiang, Pengfei; Gao, Wenliang; Cong, Rihong; Yang, Tao

    2017-11-20

    6H and 3C perovskites are important prototype structures in materials science. We systemically studied the structural evolution induced by the Sr 2+ -to-Ba 2+ substitution to the parent 6H perovskite Ba 3 ZnSb 2 O 9 . The 6H perovskite is only stable in the narrow range of x ≤ 0.2, which attributes to the impressibility of [Sb 2 O 9 ]. The preference of 90° Sb-O-Sb connection and the strong Sb 5+ -Sb 5+ electrostatic repulsion in [Sb 2 O 9 ] are competitive factors to stabilize or destabilize the 6H structure when chemical pressure was introduced by Sr 2+ incorporation. Therefore, in the following, a wide two-phase region containing 1:2 ordered 6H-Ba 2.8 Sr 0.2 ZnSb 2 O 9 and rock-salt ordered 3C-Ba 2 SrZnSb 2 O 9 was observed (0.3 ≤ x ≤ 1.0). In the final, the successive symmetry descending was established from cubic (Fm3̅m, 1.3 ≤ x ≤ 1.8) to tetragonal (I4/m, 2.0 ≤ x ≤ 2.4), and finally to monoclinic (I2/m, 2.6 ≤ x ≤ 3.0). Here we proved that the electronic configurations of B-site cations, with either empty, partially, or fully filled d-shell, would also affect the structure stabilization, through the orientation preference of the B-O covalent bonding. Our investigation gives a deeper understanding of the factors to the competitive formation of perovskite structures, facilitating the fine manipulation on their physical properties.

  16. Molecular Self-Assembly Fabrication and Carrier Dynamics of Stable and Efficient CH3 NH3 Pb(1-x) Snx I3 Perovskite Solar Cells.

    Science.gov (United States)

    Fan, Jiandong; Liu, Chong; Li, Hongliang; Zhang, Cuiling; Li, Wenzhe; Mai, Yaohua

    2017-10-09

    The Sn-based perovskite solar cells (PSCs) provide the possibility of swapping the Pb element toward developing toxic-free PSCs. Here, we innovatively employed a molecular self-assembly approach to obtain a series CH 3 NH 3 Pb (1-x) Sn x I 3 (0≤x≤1) perovskite thin films with full coverage. The optimized planar CH 3 NH 3 Pb 0.75 Sn 0.25 I 3 PSC with inverted structure was consequently realized with a maximum power conversion efficiency (PCE) over 14 %, which displayed a stabilized power output (SPO) over 12 % within 200 s at 0.6 V forward bias. Afterward, we investigated the factors that limited the efficiency improvement of hybrid Sn-Pb PSCs, and analyzed the possible reason of the hysteresis effect occurred even in the inverted structure cell. Particularly, the oxidation of hybrid Sn-Pb perovskite thin film was demonstrated to be the main reason that limited its further efficiency improvement. The imbalance of charge transport was intensified, which was associated with the increased hole defect-state density and decreased electron defect-state density after Sn was introduced. This study helps tackle the intractable issue regarding the toxic Pb in perovskite devices and is a step forward toward realizing lead-free PSCs with high stability and efficiency. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Synthesis, structure and total conductivity of A-site doped LaTiO3−δ perovskites

    International Nuclear Information System (INIS)

    Bradha, M.; Hussain, S.; Chakravarty, Sujay; Amarendra, G.; Ashok, Anuradha

    2015-01-01

    Highlights: • A-site divalent alkaline earth metal doped LaTiO 3−δ perovskites were synthesised by sol–gel method. • Structural studies revealed no change in crystal symmetry but change in cell dimensions after doping. • After doping divalent cations in A-site, an enhancement in total conductivity was observed in LaTiO 3−δ . • Temperature dependent electrical property was observed in all synthesised perovskites. - Abstract: Oxygen deficient perovskites LaTiO 3−δ and La 0.8 A 0.2 TiO 3−δ (A = Ba, Sr, Ca) were synthesized by sol–gel method. The effect of divalent dopants on microstructure is investigated in detail using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The oxidation states of La 3+ and Ti 3+ ions have been deduced using X-ray Photoelectron Spectroscopy (XPS). Impedance spectroscopy was used to analyze the total conductivity, an increase in conductivity was observed after doping in the A-site with divalent cations Ba, Ca and Sr. Among the investigated perovskites La 0.8 Ca 0.2 TiO 3−δ exhibited the maximum conductivity of 1.22 × 10 −2 S/cm in air atmosphere at 650 °C

  18. Evidence for a different electronic configuration as a primary effect during compression of orthorhombic perovskites: The case of Nd M3 +O3 (M =Cr ,Ga )

    Science.gov (United States)

    Ardit, M.; Dondi, M.; Merli, M.; Cruciani, G.

    2018-02-01

    (Mg ,Fe ) Si O3 perovskite is the most abundant mineral of the Earth's lower mantle, and compounds with the perovskite structure are perhaps the most widely employed ceramics. Hence, they attract both geophysicists and material scientists. Several investigations attempted to predict their structural evolution at high pressure, and recent advancements highlighted that perovskites having ions with the same formal valence at both polyhedral sites (i.e., 3 +:3 + ) define different compressional patterns when transition metal ions (TMI) are involved. In this study, in situ high-pressure synchrotron XRD measurements coupled with ab initio simulations of the electronic population of NdCr O3 perovskite are compared with the compressional feature of NdGa O3 . Almost identical from a steric point of view (C r3 + and G a3 + have almost the same ionic radius), the different electronic configuration of octahedrally coordinated ions - which leads to a redistribution of electrons at the 3 d orbitals for C r3 + - allows the crystal field stabilization energy (CFSE) to act as a vehicle of octahedral softening in NdCr O3 or it turns octahedra into rigid units when CFSE is null as in NdGa O3 . Besides to highlight that different electronic configurations can act as a primary effect during compression of perovskite compounds, our findings have a deep repercussion on the way the compressibility of perovskites have to be modeled.

  19. Elastic properties of cubic perovskite BaRuO{sub 3} from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Han Deming; Liu Xiaojuan; Lv Shuhui; Li Hongping [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng Jian, E-mail: jmeng@ciac.jl.c [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2010-08-01

    We present first-principles investigations on the structural and elastic properties of the cubic perovskite BaRuO{sub 3} using density-functional theory within both local density approximation (LDA) and generalized gradient approximation (GGA). Basic physical properties, such as lattice constant, shear modulus, elastic constants (C{sub ij}) are calculated. The calculated energy band structures show that the cubic perovskite BaRuO{sub 3} is metallic. We have also predicted the Young's modulus (Y), Poisson's ratio ({upsilon}), and Anisotropy factor (A).

  20. Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites.

    Science.gov (United States)

    Meng, Weiwei; Wang, Xiaoming; Xiao, Zewen; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

    2017-07-06

    Using density functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB 2+ X 3 ) and double perovskites (A 2 B + B 3+ X 6 ) (A = Cs or monovalent organic ion, B 2+ = non-Pb divalent metal, B + = monovalent metal, B 3+ = trivalent metal, X = halogen). We show that if B 2+ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect band gap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct band gaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell applications. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely, those with B + = In, Tl and B 3+ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

  1. Luminescent manganese-doped CsPbCl3 perovskite quantum dots

    NARCIS (Netherlands)

    Lin, Chun Che; Xu, Kun Yuan; Wang, Da; Meijerink, A|info:eu-repo/dai/nl/075044986

    2017-01-01

    Nanocrystalline cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) form an exciting new class of semiconductor materials showing quantum confinement. The emission color can be tuned over the full visible spectral region making them promising for light‒emitting applications. Further control

  2. Conducting Layered Organic-inorganic Halides Containing -Oriented Perovskite Sheets.

    Science.gov (United States)

    Mitzi, D B; Wang, S; Feild, C A; Chess, C A; Guloy, A M

    1995-03-10

    Single crystals of the layered organic-inorganic perovskites, [NH(2)C(I=NH(2)](2)(CH(3)NH(3))m SnmI3m+2, were prepared by an aqueous solution growth technique. In contrast to the recently discovered family, (C(4)H(9)NH(3))(2)(CH(3)NH(3))n-1SnnI3n+1, which consists of (100)-terminated perovskite layers, structure determination reveals an unusual structural class with sets of m -oriented CH(3)NH(3)SnI(3) perovskite sheets separated by iodoformamidinium cations. Whereas the m = 2 compound is semiconducting with a band gap of 0.33 +/- 0.05 electron volt, increasing m leads to more metallic character. The ability to control perovskite sheet orientation through the choice of organic cation demonstrates the flexibility provided by organic-inorganic perovskites and adds an important handle for tailoring and understanding lower dimensional transport in layered perovskites.

  3. Comparison of Cadmium-Zinc-Telluride semiconductor and Yttrium-Aluminum-Perovskite scintillator as photon detectors for epithermal neutron spectroscopy

    International Nuclear Information System (INIS)

    Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Gorini, G.; Imberti, S.; Perelli-Cippo, E.; Senesi, R.; Rhodes, N.; Schooneveld, E.M.

    2006-01-01

    The range of applications of epithermal neutron scattering experiments has been recently extended by the development of the Resonance Detector. In a Resonance Detector, resonant neutron absorption in an analyzer foil results in prompt emission of X- and γ-rays which are detected by a photon counter. Several combinations of analyzer foils and photon detectors have been studied and tested over the years and best results have been obtained with the combination of a natural uranium and (i) Cadmium-Zinc-Telluride (CZT) semiconductor (ii) Yttrium-Aluminum-Perovskite (YAP) scintillators. Here we compare the performance of the CZT semiconductor and YAP scintillator as Resonance Detector units. Two Resonance Detector prototypes made of natural uranium foil viewed by CZT and YAP were tested on the VESUVIO spectrometer at the ISIS spallation neutron source. The results show that both YAP and CZT can be used to detect epithermal neutrons in the energy range from 1 up to 66 eV. It was found that the signal-to-background ratio of the measurement can significantly be improved by raising the lower level discrimination threshold on the γ energy to about 600 keV. The advantages/disadvantages of the choice of a Resonance Detector based on YAP or CZT are discussed together with some potential applications

  4. Photovoltaic properties of Cu-doped CH3NH3PbI3 with perovskite structure

    Science.gov (United States)

    Shirahata, Yasuhiro; Oku, Takeo

    2017-01-01

    Photovoltaic properties of copper (Cu)-doped perovskite (CH3NH3PbCuxI3+x) photovoltaic devices with different Cu content were investigated. The CH3NH3PbCuxI3+x films were polycrystalline with a tetragonal system, and their lattice constants and crystallite size varied with Cu doping. Compared to conversion efficiencies of non-doped CH3NH3PbI3 photovoltaic device, those of CH3NH3PbCuxI3+x photovoltaic devises increased. The improvement of photovoltaic properties was attributed to partial substitution of Cu at the Pb sites.

  5. Perovskite-based heterostructures integrating ferromagnetic-insulating La0.1Bi0.9MnO3

    Science.gov (United States)

    Gajek, M.; Bibes, M.; Barthélémy, A.; Varela, M.; Fontcuberta, J.

    2005-05-01

    We report on the growth of thin films and heterostructures of the ferromagnetic-insulating perovskite La0.1Bi0.9MnO3. We show that the La0.1Bi0.9MnO3 perovskite grows single phased, epitaxially, and with a single out-of-plane orientation either on SrTiO3 substrates or onto strained La2/3Sr1/3MnO3 and SrRuO3 ferromagnetic-metallic buffer layers. We discuss the magnetic properties of the La0.1Bi0.9MnO3 films and heterostructures in view of their possible potential as magnetoelectric or spin-dependent tunneling devices.

  6. 2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Haichuan; Hosaka, Yoshiteru; Seki, Hayato; Saito, Takashi; Ichikawa, Noriya [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Shimakawa, Yuichi, E-mail: shimak@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Integrated Research Consortium on Chemical Sciences, Uji, Kyoto 611-0011 (Japan)

    2017-02-15

    La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.

  7. Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

    International Nuclear Information System (INIS)

    Gosavi, Priti V.; Biniwale, Rajesh B.

    2010-01-01

    Three different wet chemistry routes, namely co-precipitation, combustion and sol-gel methods were used to synthesize LaFeO 3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer-Emmett-Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol-gel method yields comparatively pure, crystalline phase of LaFeO 3 and relatively higher surface area of 16.5 m 2 g -1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol-gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO 3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods.

  8. Structural properties, electric response and electronic feature of BaSnO3 perovskite

    International Nuclear Information System (INIS)

    Cuervo Farfan, J.; Arbey Rodriguez, J.; Fajardo, F.; Vera Lopez, E.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2009-01-01

    It has been observed that the semiconducting compound SnO 2 presents very good results as gas sensor. One important development has been performed to study perovskite oxides for this relevant application. One oxide material which constitutes an excellent candidate for this technological application is BaSnO 3 . Polycrystalline samples with single phase of BaSnO 3 were synthesized by using the solid state reaction method. Samples were characterized structurally by means of X-ray diffraction (XRD) technique. Rietveld refinement, by using the GSAS code, reveals that this material synthesizes in a cubic perovskite, space group Pm3m (no. 221), with lattice parameter 4.1190(3)A. Electric response was examined through the impedance spectroscopy technique. Results of Bode diagram, from an equivalent circuit, evidence the semiconductor character of material. We carried out a theoretical study by means of the calculation of the bands diagram and the density of states of the BaSnO 3 . Calculation was performed by employing the density functional theory (DFT), with the generalized gradient approach (GGA). DFT theory permitted to establish that BaSnO 3 material has an indirect semiconducting behavior. The calculated gap for this perovskite-like stagnate is at least 0.4 eV. Bulk modulus for material was also determined to be 132 GPa.

  9. Ag modified LaCoO3 perovskite oxide for photocatalytic application

    Science.gov (United States)

    Jayapandi, S.; Prakasini, V. Anitha; Anitha, K.

    2018-04-01

    The present investigation has been carried out to develop a novel photocatalytic material based on lanthanum cobaltite (LaCoO3) and silver (Ag) doped LaCoO3 perovskite oxide. Pure LaCoO3 and 5 Mol% Ag doped LaCoO3 (Ag-LaCoO3) have been synthesized by simple co-precipitation method and characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and photoluminescence (PL) techniques and its photocatalytic activity was evaluated by photodegradation of methylene blue under sunlight irradiation. The observed XRD, UV and PL results indicate that Ag influences on the crystallite size and absorption coefficient of LaCoO3 perovskite oxide. The percentage of dye degradations was calculated as 60% and 99 % for LaCoO3 and 5 Mol% Ag-LaCoO3 pervoskite oxides respectively for 10 minutes (10 min) exposure to sunlight, which indicates that 5 mol% of Ag-LaCoO3, has better photodegradation activity. Hence, the present investigation confirms that Ag influences the photocatalytic activity of a material and the observations will be helpful for further developing new photocatalytic materials.

  10. Efficient Luminescence from Perovskite Quantum Dot Solids

    KAUST Repository

    Kim, Younghoon; Yassitepe, Emre; Voznyy, Oleksandr; Comin, Riccardo; Walters, Grant; Gong, Xiwen; Kanjanaboos, Pongsakorn; Nogueira, Ana F.; Sargent, Edward H.

    2015-01-01

    © 2015 American Chemical Society. Nanocrystals of CsPbX3 perovskites are promising materials for light-emitting optoelectronics because of their colloidal stability, optically tunable bandgap, bright photoluminescence, and excellent photoluminescence quantum yield. Despite their promise, nanocrystal-only films of CsPbX3 perovskites have not yet been fabricated; instead, highly insulating polymers have been relied upon to compensate for nanocrystals' unstable surfaces. We develop solution chemistry that enables single-step casting of perovskite nanocrystal films and overcomes problems in both perovskite quantum dot purification and film fabrication. Centrifugally cast films retain bright photoluminescence and achieve dense and homogeneous morphologies. The new materials offer a platform for optoelectronic applications of perovskite quantum dot solids.

  11. Efficient Luminescence from Perovskite Quantum Dot Solids

    KAUST Repository

    Kim, Younghoon

    2015-11-18

    © 2015 American Chemical Society. Nanocrystals of CsPbX3 perovskites are promising materials for light-emitting optoelectronics because of their colloidal stability, optically tunable bandgap, bright photoluminescence, and excellent photoluminescence quantum yield. Despite their promise, nanocrystal-only films of CsPbX3 perovskites have not yet been fabricated; instead, highly insulating polymers have been relied upon to compensate for nanocrystals\\' unstable surfaces. We develop solution chemistry that enables single-step casting of perovskite nanocrystal films and overcomes problems in both perovskite quantum dot purification and film fabrication. Centrifugally cast films retain bright photoluminescence and achieve dense and homogeneous morphologies. The new materials offer a platform for optoelectronic applications of perovskite quantum dot solids.

  12. Optically stimulated luminescence properties of Tm{sup 3+} doped KMgF{sub 3} fluoro perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, L.; Marcazzo, J. [UNCPBA, Facultad de Ciencias Exactas, Instituto de Fisica Arroyo Seco, Gral. Pinto 399, B7000GHG Tandil, Buenos Aires (Argentina); Perez C, L.; Cruz Zaragoza, E. [UNAM, Instituto de Ciencias Nucleares, Apdo. Postal 70543, 04510 Ciudad de Mexico (Mexico); Martinez O, S. A., E-mail: jmarcass@exa.unicen.edu.ar [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte 39-115, 150003 Tunja, Bocaya (Colombia)

    2017-10-15

    In this work the optically stimulated luminescence (OSL) properties of undoped and Tm{sup 3+} doped KMgF{sub 3} fluoro perovskite have been investigated for the first time. OSL efficiency for stimulation with different wavelengths has been analyzed for each compound. The maximum OSL emission was found with blue light stimulation. The radioluminescence (Rl) spectra have shown two emission peaks at 455 and 360 nm, which can be ascribed to the {sup 1}D{sub 2}-{sup 3}F{sub 4} and {sup 1}D{sub 2}-{sup 3}H{sub 6} transitions of the Tm{sup 3+} cations. It has been found that doping with Thulium 0.5 mol % renders the most intense OSL emission. Furthermore, several dosimetric properties such as OSL response as a function of dose, reproducibility of the OSL signal after several cycles of irradiation readout and the minimum detectable dose have been investigated. Finally, the OSL response of KMgF{sub 3}: Tm{sup 3+} has been compared to that of commercial Al{sub 2}O{sub 3}:C and the possible application of this fluoro perovskite to OSL dosimetry has been evaluated. (Author)

  13. Homogeneous Emission Line Broadening in the Organo Lead Halide Perovskite CH3NH3PbI3-xClx.

    Science.gov (United States)

    Wehrenfennig, Christian; Liu, Mingzhen; Snaith, Henry J; Johnston, Michael B; Herz, Laura M

    2014-04-17

    The organic-inorganic hybrid perovskites methylammonium lead iodide (CH3NH3PbI3) and the partially chlorine-substituted mixed halide CH3NH3PbI3-xClx emit strong and broad photoluminescence (PL) around their band gap energy of ∼1.6 eV. However, the nature of the radiative decay channels behind the observed emission and, in particular, the spectral broadening mechanisms are still unclear. Here we investigate these processes for high-quality vapor-deposited films of CH3NH3PbI3-xClx using time- and excitation-energy dependent photoluminescence spectroscopy. We show that the PL spectrum is homogenously broadened with a line width of 103 meV most likely as a consequence of phonon coupling effects. Further analysis reveals that defects or trap states play a minor role in radiative decay channels. In terms of possible lasing applications, the emission spectrum of the perovskite is sufficiently broad to have potential for amplification of light pulses below 100 fs pulse duration.

  14. Group theoretical analysis of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Howard, C.J.; Stokes, H.T.

    1998-01-01

    Full text: Structures of the perovskite family, ABX 3 , have interested crystallographers over many years, and continue to attract attention on account of their fascinating electrical and magnetic properties, for example the giant magnetoresistive effects exhibited by certain perovskite materials. The ideal perovskite (cubic, space group Pm -/3 m) is a particularly simple structure, but also a demanding one, since aside from the lattice parameter there are no variable parameters in the structure. Consequently, the majority of perovskite structures are distorted perovskites (hettotypes), the most common distortion being the corner-linked tilting of the practically rigid BX 6 octahedral units. In this work, group theoretical methods have been applied to the study of octahedral tilting in perovskites. The only irreducible representations of the parent group (Pm -/3 m) which produce octahedral tilting subject to corner-linking constraints are M + / 3 and R 4 ' + . A six-dimensional order parameter in the reducible representation space of M + / 3 + R + / 4 describes the different possible tilting patterns. The space groups for the different perovskites are then simply the isotropy subgroups, comprising those operations which leave the order parameter invariant. The isotropy subgroups are obtained from a computer program or tabulations. The analysis yields a list of fifteen possible space groups for perovskites derived through octahedral tilting. A connection is made to the (twenty-three) tilt systems given previously by Glazer. The group-subgroup relationships have been derived and displayed. It is interesting to note that all known perovskites based on octahedral tilting conform with the fifteen space groups on our list, with the exception of one perovskite at high temperature, the structure of which seems poorly determined

  15. Symmetry mismatch-driven perpendicular magnetic anisotropy for perovskite/brownmillerite heterostructures.

    Science.gov (United States)

    Zhang, Jing; Zhong, Zhicheng; Guan, Xiangxiang; Shen, Xi; Zhang, Jine; Han, Furong; Zhang, Hui; Zhang, Hongrui; Yan, Xi; Zhang, Qinghua; Gu, Lin; Hu, Fengxia; Yu, Richeng; Shen, Baogen; Sun, Jirong

    2018-05-15

    Grouping different transition metal oxides together by interface engineering is an important route toward emergent phenomenon. While most of the previous works focused on the interface effects in perovskite/perovskite heterostructures, here we reported on a symmetry mismatch-driven spin reorientation toward perpendicular magnetic anisotropy in perovskite/brownmillerite heterostructures, which is scarcely seen in tensile perovskite/perovskite heterostructures. We show that alternately stacking perovskite La 2/3 Sr 1/3 MnO 3 and brownmillerite LaCoO 2.5 causes a strong interface reconstruction due to symmetry discontinuity at interface: neighboring MnO 6 octahedra and CoO 4 tetrahedra at the perovskite/brownmillerite interface cooperatively relax in a manner that is unavailable for perovskite/perovskite interface, leading to distinct orbital reconstructions and thus the perpendicular magnetic anisotropy. Moreover, the perpendicular magnetic anisotropy is robust, with an anisotropy constant two orders of magnitude greater than the in-plane anisotropy of the perovskite/perovskite interface. The present work demonstrates the great potential of symmetry engineering in designing artificial materials on demand.

  16. Ligand-Stabilized Reduced-Dimensionality Perovskites

    KAUST Repository

    Quan, Li Na; Yuan, Mingjian; Comin, Riccardo; Voznyy, Oleksandr; Beauregard, Eric M.; Hoogland, Sjoerd; Buin, Andrei; Kirmani, Ahmad R.; Zhao, Kui; Amassian, Aram; Kim, Dong Ha; Sargent, Edward H.

    2016-01-01

    Metal halide perovskites have rapidly advanced thin film photovoltaic performance; as a result, the materials’ observed instabilities urgently require a solution. Using density functional theory (DFT), we show that a low energy of formation, exacerbated in the presence of humidity, explains the propensity of perovskites to decompose back into their precursors. We find, also using DFT, that intercalation of phenylethylammonium between perovskite layers introduces quantitatively appreciable van der Waals interactions; and these drive an increased formation energy and should therefore improve material stability. Here we report the reduced-dimensionality (quasi-2D) perovskite films that exhibit improved stability while retaining the high performance of conventional three-dimensional perovskites. Continuous tuning of the dimensionality, as assessed using photophysical studies, is achieved by the choice of stoichiometry in materials synthesis. We achieved the first certified hysteresis-free solar power conversion in a planar perovskite solar cell, obtaining a 15.3% certified PCE, and observe greatly improved performance longevity.

  17. Ligand-Stabilized Reduced-Dimensionality Perovskites

    KAUST Repository

    Quan, Li Na

    2016-02-03

    Metal halide perovskites have rapidly advanced thin film photovoltaic performance; as a result, the materials’ observed instabilities urgently require a solution. Using density functional theory (DFT), we show that a low energy of formation, exacerbated in the presence of humidity, explains the propensity of perovskites to decompose back into their precursors. We find, also using DFT, that intercalation of phenylethylammonium between perovskite layers introduces quantitatively appreciable van der Waals interactions; and these drive an increased formation energy and should therefore improve material stability. Here we report the reduced-dimensionality (quasi-2D) perovskite films that exhibit improved stability while retaining the high performance of conventional three-dimensional perovskites. Continuous tuning of the dimensionality, as assessed using photophysical studies, is achieved by the choice of stoichiometry in materials synthesis. We achieved the first certified hysteresis-free solar power conversion in a planar perovskite solar cell, obtaining a 15.3% certified PCE, and observe greatly improved performance longevity.

  18. Efficient Inorganic Perovskite Light-Emitting Diodes with Polyethylene Glycol Passivated Ultrathin CsPbBr3 Films.

    Science.gov (United States)

    Song, Li; Guo, Xiaoyang; Hu, Yongsheng; Lv, Ying; Lin, Jie; Liu, Zheqin; Fan, Yi; Liu, Xingyuan

    2017-09-07

    Efficient inorganic perovskite light-emitting diodes (PeLEDs) with an ultrathin perovskite emission layer (∼30 nm) were realized by doping Lewis base polyethylene glycol (PEG) into CsPbBr 3 films. PEG in the perovskite films not only physically fills the crystal boundaries but also interacts with the perovskite crystals to passivate the crystal grains, reduce nonradiative recombination, and ensure efficient luminance and high efficiency. As a result, promoted brightness, current efficiency (CE), and external quantum efficiency (EQE) were achieved. The nonradiative decay rate of the PEG:CsPbBr 3 composite film is 1 order of magnitude less than that of the neat CsPbBr 3 film. After further optimization of the molar ratio between CsBr and PbBr 2 , a peak CE of 19 cd/A, a maximum EQE of 5.34%, and a maximum brightness of 36600 cd/m 2 were achieved, demonstrating the interaction between PEG and the precursors. The results are expected to offer some helpful implications in optimizing the polymer-assisted PeLEDs with ultrathin emission layers, which might have potential application in see-through displays.

  19. Making and Breaking of Lead Halide Perovskites

    KAUST Repository

    Manser, Joseph S.

    2016-02-16

    kinetics can be tailored to yield improved thin film homogeneity. Because degradation of the as-formed perovskite film is in many ways analogous to its initial formation, the same suite of monitoring techniques reveals the moisture-induced transformation of low band gap methylammonium lead iodide (CH3NH3PbI3) to wide band gap hydrate compounds. The rate of degradation is increased upon exposure to light. Interestingly, the hydration process is reversible under certain conditions. This facile formation and subsequent chemical lability raises the question of whether CH3NH3PbI3 and its analogues are thermodynamically stable phases, thus posing a significant challenge to the development of transformative perovskite photovoltaics. Adequately addressing issues of structural and chemical stability under real-world operating conditions is paramount if perovskite solar cells are to make an impact beyond the benchtop. Expanding our fundamental knowledge of lead halide perovskite formation and degradation pathways can facilitate fabrication of stable, high-quality perovskite thin films for the next generation of photovoltaic and light emitting devices.

  20. Phonon model of perovskite thermal capacity

    International Nuclear Information System (INIS)

    Kesler, Ya.A.; Poloznikova, M.Eh.; Petrov, K.I.

    1983-01-01

    A model for calculating the temperature curve of thermal capacity of perovskite family crystals on the basis of vibrational spectra is proposed. Different representatives of the perovskite family: cubic SrTiO 3 , tetragonal BaTiO 3 and orthorbombic CaTiO 3 and LaCrO 3 are considered. The total frequency set is used in thermal capacity calcUlations. Comparison of the thermal capacity values of compounds calculated on the basis of the proposed model with the experimental values shows their good agreement. The method is also recommended for other compounds with the perovskite-like structure

  1. Acoustic phonons in the hexagonal perovskite CsNiCl3 around the Gamma-point

    DEFF Research Database (Denmark)

    Visser, D.; Monteith, A.R.; Rønnow, H.M.

    2000-01-01

    The acoustic phonon dispersion curves of the hexagonal perovskite CsNiCl3 were measured at room temperature in the vicinity of the Gamma-point along the [0 0 1] and [1 1 0] directions. The derived velocity of sound values for the longitudinal and transverse acoustic phonons are compared with the ......The acoustic phonon dispersion curves of the hexagonal perovskite CsNiCl3 were measured at room temperature in the vicinity of the Gamma-point along the [0 0 1] and [1 1 0] directions. The derived velocity of sound values for the longitudinal and transverse acoustic phonons are compared...

  2. Oxyfluoride Chemistry of Layered Perovskite Compounds

    Directory of Open Access Journals (Sweden)

    Yoshihiro Tsujimoto

    2012-03-01

    Full Text Available In this paper, we review recent progress and new challenges in the area of oxyfluoride perovskite, especially layered systems including Ruddlesden-Popper (RP, Dion-Jacobson (DJ and Aurivillius (AV type perovskite families. It is difficult to synthesize oxyfluoride perovskite using a conventional solid-state reaction because of the high chemical stability of the simple fluoride starting materials. Nevertheless, persistent efforts made by solid-state chemists have led to a major breakthrough in stabilizing such a mixed anion system. In particular, it is known that layered perovskite compounds exhibit a rich variety of O/F site occupation according to the synthesis used. We also present the synthetic strategies to further extend RP type perovskite compounds, with particular reference to newly synthesized oxyfluorides, Sr2CoO3F and Sr3Fe2O5+xF2−x (x ~ 0.44.

  3. The Role of Trap-assisted Recombination in Luminescent Properties of Organometal Halide CH3NH3PbBr3 Perovskite Films and Quantum Dots

    Science.gov (United States)

    Zhang, Zhen-Yu; Wang, Hai-Yu; Zhang, Yan-Xia; Hao, Ya-Wei; Sun, Chun; Zhang, Yu; Gao, Bing-Rong; Chen, Qi-Dai; Sun, Hong-Bo

    2016-06-01

    Hybrid metal halide perovskites have been paid enormous attentions in photophysics research, whose excellent performances were attributed to their intriguing charge carriers proprieties. However, it still remains far from satisfaction in the comprehensive understanding of perovskite charge-transport properities, especially about trap-assisted recombination process. In this Letter, through time-resolved transient absorption (TA) and photoluminescence (PL) measurements, we provided a relative comprehensive investigation on the charge carriers recombination dynamics of CH3NH3PbBr3 (MAPbBr3) perovskite films and quantum dots (QDs), especially about trap-assisted recombination. It was found that the integral recombination mode of MAPbBr3 films was highly sensitive to the density distribution of generated charge carriers and trap states. Additional, Trap effects would be gradually weakened with elevated carrier densities. Furthermore, the trap-assisted recombination can be removed from MAPbBr3 QDs through its own surface passivation mechanism and this specialty may render the QDs as a new material in illuminating research. This work provides deeper physical insights into the dynamics processes of MAPbBr3 materials and paves a way toward more light-harvesting applications in future.

  4. Carbon-Based CsPbBr3 Perovskite Solar Cells: All-Ambient Processes and High Thermal Stability.

    Science.gov (United States)

    Chang, Xiaowen; Li, Weiping; Zhu, Liqun; Liu, Huicong; Geng, Huifang; Xiang, Sisi; Liu, Jiaming; Chen, Haining

    2016-12-14

    The device instability has been an important issue for hybrid organic-inorganic halide perovskite solar cells (PSCs). This work intends to address this issue by exploiting inorganic perovskite (CsPbBr 3 ) as light absorber, accompanied by replacing organic hole transport materials (HTM) and the metal electrode with a carbon electrode. All the fabrication processes (including those for CsPbBr 3 and the carbon electrode) in the PSCs are conducted in ambient atmosphere. Through a systematical optimization on the fabrication processes of CsPbBr 3 film, carbon-based PSCs (C-PSCs) obtained the highest power conversion efficiency (PCE) of about 5.0%, a relatively high value for inorganic perovskite-based PSCs. More importantly, after storage for 250 h at 80 °C, only 11.7% loss in PCE is observed for CsPbBr 3 C-PSCs, significantly lower than that for popular CH 3 NH 3 PbI 3 C-PSCs (59.0%) and other reported PSCs, which indicated a promising thermal stability of CsPbBr 3 C-PSCs.

  5. Plastic Properties of MgSiO3 Post-Perovskite in the Lower Mantle : Do We Care about Twinning ?

    Science.gov (United States)

    Carrez, P.; Goryaeva, A.; Cordier, P.

    2017-12-01

    Plastic properties of post-perovskite MgSiO3 are believed to be one of the key issues for the understanding of seismic anisotropy at the bottom of the D'' layer. Unfortunately, results from high pressure deformation experiments have led to several conflicting interpretations regarding slip systems and dislocation activities. Whereas, plastic slip has attracted much more attention, twinning mechanism has not been addressed despite some experimental evidence on low-pressure analogues. Based on a hierarchical mechanical model of the emission of 1/6 partial dislocations, we present a twin nucleation model in MgSiO3 and CaIrO3 post-perovskite. Relying on first-principles calculations, we show that {110} twin wall formation resulting from the interaction of multiple twin dislocations occurs for twinning stress comparable to the easiest slip system in post-perovskite. Dislocations activities and twinning being competitive strain producing mechanism, twinning has to be considered in future interpretation of crystallographic preferred orientations in post-perovskite.

  6. Preparation and characterization of organic-inorganic hybrid perovskite (C4H9NH3)2CuCl4

    International Nuclear Information System (INIS)

    Xiao Zelong; Chen Hongzheng; Shi Minmin; Wu Gang; Zhou Renjia; Yang Zhisheng; Wang Mang; Tang Benzhong

    2005-01-01

    Organic-inorganic hybrid perovskite (C 4 H 9 NH 3 ) 2 CuCl 4 was prepared via the reaction between copper chloride and butylammonium chloride. Its chemical structure was characterized by FT-IR and elemental analysis. Its thin film was obtained by spin-coating, and X-ray diffraction (XRD) measurements indicated the formation of two-dimensional layered perovskites structure, with the c-axis perpendicular to the substrate surface. The electronic structure, thermal properties and electrical properties of the hybrid perovskite (C 4 H 9 NH 3 ) 2 CuCl 4 were also studied by UV-vis, photoluminescience (PL), TGA, DSC, and Hall measurement

  7. A Study of Inverted-Type Perovskite Solar Cells with Various Composition Ratios of (FAPbI31−x(MAPbBr3x

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2016-10-01

    Full Text Available This work presents mixed (FAPbI31−x(MAPbBr3x perovskite films with various composition ratios, x (x = 0–1, which are formed using the spin coating method. The structural, optical, and electronic behaviors of the mixed (FAPbI31−x(MAPbBr3x perovskite films are discussed. A device with structure glass/indium tin oxide (ITO/poly(3,4-ethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS/mixed perovskite/C60/BCP/Ag was fabricated. The mixed perovskite film was an active light-harvesting layer. PEDOT:PSS was a hole transporting layer between the ITO and perovskite. Both C60 and bathocuproine (BCP were electron transporting layers. MAPbBr3 was added to FAPbI3 with a composition ratio of x = 0.2, stabilizing the perovskite phase, which exhibited a uniform and dense morphology. The optimal device exhibited band matching with C60, resulting in a low series resistance (Rsh and a high fill factor (FF. Therefore, the device with composition (FAPbI31−x(MAPbBr3x and x = 0.2 exhibited outstanding performance.

  8. Tracking the formation of methylammonium lead triiodide perovskite

    International Nuclear Information System (INIS)

    Liu, Lijia; McLeod, John A.; Wang, Rongbin; Shen, Pengfei; Duhm, Steffen

    2015-01-01

    The formation mechanism of perovskite methylammonium lead triiodide (CH 3 NH 3 PbI 3 ) was studied with in situ X-ray photoelectron spectroscopy (XPS) on successive depositions of thermally evaporated methylammonium iodide (CH 3 NH 3 I) on a lead iodide (PbI 2 ) film. This deposition method mimics the “two-step” synthesis method commonly used in device fabrication. We find that several competing processes occur during the formation of perovskite CH 3 NH 3 PbI 3 . Our most important finding is that during vapour deposition of CH 3 NH 3 I onto PbI 2 , at least two carbon species are present in the resulting material, while only one nitrogen species is present. This suggests that CH 3 NH 3 I can dissociate during the transition to a perovskite phase, and some of the resulting molecules can be incorporated into the perovskite. The effect of partial CH 3 NH 3 substitution with CH 3 was evaluated, and electronic structure calculations show that CH 3 defects would impact the photovoltaic performance in perovskite solar cells. The possibility that not all A sites in the APbI 3 perovskite are occupied by CH 3 NH 3 is therefore an important consideration when evaluating the performance of organometallic trihalide solar cells synthesized using typical approaches

  9. Chemically tailoring the dopant emission in manganese-doped CsPbCl{sub 3} perovskite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Das Adhikari, Samrat; Dutta, Sumit K.; Dutta, Anirban; Guria, Amit K.; Pradhan, Narayan [Department of Materials Science, Indian Association for the Cultivation of Science, Kolkata (India)

    2017-07-17

    Doping in perovskite nanocrystals adopts different mechanistic approach in comparison to widely established doping in chalcogenide quantum dots. The fast formation of perovskites makes the dopant insertions more competitive and challenging. Introducing alkylamine hydrochloride (RNH{sub 3}Cl) as a promoting reagent, precise controlled doping of Mn{sup II} in CsPbCl{sub 3} perovskite nanocrystals is reported. Simply, by changing the amount of RNH{sub 3}Cl, the Mn incorporation and subsequent tuning in the excitonic as well as Mn d-d emission intensities are tailored. Investigations suggested that RNH{sub 3}Cl acted as the chlorinating source, controlled the size, and also helps in increasing the number of particles. This provided more opportunity for Mn ions to take part in reaction and occupied the appropriate lattice positions. Carrying out several reactions with varying reaction parameters, the doping conditions are optimized and the role of the promoting reagent for both doped and undoped systems are compared. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. First-principles prediction of structural, elastic, electronic and thermodynamic properties of the cubic SrUO{sub 3}-Perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Sahli, B. [Laboratoire de Génie Physique, Université Ibn Khaldoun, Tiaret, 14000 (Algeria); Laboratoire des Matériaux Magnétiques, Université Djillali Liabés, Sidi Bel-Abbes 22000 (Algeria); Bouafia, H., E-mail: hamza.tssm@gmail.com [Laboratoire de Génie Physique, Université Ibn Khaldoun, Tiaret, 14000 (Algeria); Abidri, B.; Abdellaoui, A. [Laboratoire des Matériaux Magnétiques, Université Djillali Liabés, Sidi Bel-Abbes 22000 (Algeria); Hiadsi, S.; Akriche, A. [Laboratoire de Microscope Electronique et Sciences des Matériaux, Université des Sciences et de la Technologie Mohamed Boudiaf, département de Génie Physique, BP1505 El m’naouar, Oran (Algeria); Benkhettou, N.; Rached, D. [Laboratoire des Matériaux Magnétiques, Université Djillali Liabés, Sidi Bel-Abbes 22000 (Algeria)

    2015-06-25

    Highlights: • The ground state properties of SrUO{sub 3}-Perovskite were investigated. • Elastic constants and their related parameters were calculated. • Electronic properties are treated using GGA-PBEsol + U approach. - Abstract: In this paper, we investigate bulk properties of the cubic SrUO{sub 3}-Perovskite in their nonmagnetic (NM), antiferromagnetic (AFM) and ferromagnetic (FM) states using all-electron self consistent Full Potential Augmented Plane Waves plus local orbital (FP-(L)APW + lo) method within PBEsol Generalized Gradiant density approximations. Our calculation allowed us to predict that the more stable magnetic state of the cubic SrUO{sub 3}-Perovskite is that of the ferromagnetic (FM). This work is the first prediction of elastic constants and their related parameters (Young modulus, shear modulus, Poisson ratio, Zener anisotropy and the Debye temperature) for this cubic compound using Mehl method. We have employed the GGA(PBEsol) and GGA(PBEsol) + U to investigate the electronic band structure, density of states and electronic charge density of SrUO{sub 3}-Perovskite. The electronic band structure calculations revealed that SrUO{sub 3} exhibits metallic behavior. On the other hand the charge density plots for [1 1 0] direction indicates a strong ionic character along the Sr–O bond while the U–O bond has strong covalent character. Finally, we have analyzed the thermodynamic properties using the quasi-harmonic Debye model to complete the fundamental characterization of cubic SrUO{sub 3}-Perovskite.

  11. Effect of A-site deficiency in LaMn_0_._9Co_0_._1O_3 perovskites on their catalytic performance for soot combustion

    International Nuclear Information System (INIS)

    Dinamarca, Robinson; Garcia, Ximena; Jimenez, Romel; Fierro, J.L.G.; Pecchi, Gina

    2016-01-01

    Highlights: • A-site defective perovskites increases the oxidation state of the B-cation. • Not always non-stoichiometric perovskites exhibit higher catalytic activity in soot combustion. • The highly symmetric cubic crystalline structure diminishes the redox properties of perovskites. - Abstract: The influence of lanthanum stoichiometry in Ag-doped (La_1_-_xAg_xMn_0_._9Co_0_._1O_3) and A-site deficient (La_1_-_xMn_0_._9Co_0_._1O_3_-_δ) perovskites with x equal to 10, 20 and 30 at.% has been investigated in catalysts for soot combustion. The catalysts were prepared by the amorphous citrate method and characterized by XRD, nitrogen adsorption, XPS, O_2-TPD and TPR. The formation of a rhombohedral excess-oxygen perovskite for Ag-doped and a cubic perovskite structure for an A-site deficient series is confirmed. The efficient catalytic performance of the larger Ag-doped perovskite structure is attributed to the rhombohedral crystalline structure, Ag_2O segregated phases and the redox pair Mn"4"+/Mn"3"+. A poor catalytic activity for soot combustion was observed with A-site deficient perovskites, despite the increase in the redox pair Mn"4"+/Mn"3"+, which is attributed to the cubic crystalline structure.

  12. High Efficiency MAPbI3 Perovskite Solar Cell Using a Pure Thin Film of Polyoxometalate as Scaffold Layer.

    Science.gov (United States)

    Sardashti, Mohammad Khaledi; Zendehdel, Mahmoud; Nia, Narges Yaghoobi; Karimian, Davud; Sheikhi, Mohammad

    2017-10-09

    Here, we successfully used a pure layer of [SiW 11 O 39 ] 8- polyoxomethalate (POM) structure as a thin-film scaffold layer for CH 3 NH 3 PbI 3 -based perovskite solar cells (PSCs). A smooth nanoporous surface of POM causes outstanding improvement of the photocurrent density, external quantum efficiency (EQE), and overall efficiency of the PSCs compared to mesoporous TiO 2 (mp-TiO 2 ) as scaffold layer. Average power conversion efficiency (PCE) values of 15.5 % with the champion device showing 16.3 % could be achieved by using POM and a sequential deposition method with the perovskite layer. Furthermore, modified and defect-free POM/perovskite interface led to elimination of the anomalous hysteresis in the current-voltage curves. The open-circuit voltage decay study shows promising decrease of the electron recombination in the POM-based PSCs, which is also related to the modification of the POM/ perovskite interface and higher electron transport inside the POM layer. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites

    KAUST Repository

    Priante, Davide; Dursun, Ibrahim; Alias, M. S.; Shi, Dong; Melnikov, V. A.; Ng, Tien Khee; Mohammed, Omar F.; Bakr, Osman; Ooi, Boon S.

    2015-01-01

    We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic radiative

  14. High-Pressure Study of Perovskites and Postperovskites in the (Mg,Fe)GeO 3 System

    Energy Technology Data Exchange (ETDEWEB)

    Stan, Camelia V.; Dutta, Rajkrishna; Cava, Robert J.; Prakapenka, Vitali B.; Duffy, Thomas S. (Princeton); (UC)

    2017-06-22

    The effect of incorporation of Fe2+ on the perovskite (Pbnm) and postperovskite (Cmcm) structures was investigated in the (Mg,Fe)GeO3 system at high pressures and temperatures using laser-heated diamond anvil cell and synchrotron X-ray diffraction. Samples with compositions of Mg# ≥ 48 were shown to transform to the perovskite (~30 GPa and ~1500 K) and postperovskite (>55 GPa, ~1600–1800 K) structures. Compositions with Mg# ≥ 78 formed single-phase perovskite and postperovskite, whereas those with Mg# < 78 showed evidence for partial decomposition. The incorporation of Fe into the perovskite structure causes a decrease in octahedral distortion as well as a modest decrease in bulk modulus (K0) and a modest increase in zero-pressure volume (V0). It also leads to a decrease in the perovskite-to-postperovskite phase transition pressure by ~9.5 GPa over compositions from Mg#78 to Mg#100.

  15. Water-Induced Dimensionality Reduction in Metal-Halide Perovskites

    KAUST Repository

    Turedi, Bekir

    2018-03-30

    Metal-halide perovskite materials are highly attractive materials for optoelectronic applications. However, the instability of perovskite materials caused by moisture and heat-induced degradation impairs future prospects of using these materials. Here we employ water to directly transform films of the three-dimensional (3D) perovskite CsPbBr3 to stable two-dimensional (2D) perovskite-related CsPb2Br5. A sequential dissolution-recrystallization process governs this water induced transformation under PbBr2 rich condition. We find that these post-synthesized 2D perovskite-related material films exhibit excellent stability against humidity and high photoluminescence quantum yield. We believe that our results provide a new synthetic method to generate stable 2D perovskite-related materials that could be applicable for light emitting device applications.

  16. A Feasible and Effective Post-Treatment Method for High-Quality CH3NH3PbI3 Films and High-Efficiency Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Yaxiao Jiang

    2018-01-01

    Full Text Available The morphology control of CH3NH3PbI3 (MAPbI3 thin-film is crucial for the high-efficiency perovskite solar cells, especially for their planar structure devices. Here, a feasible and effective post-treatment method is presented to improve the quality of MAPbI3 films by using methylamine (CH3NH2 vapor. This post-treatment process is studied thoroughly, and the perovskite films with smooth surface, high preferential growth orientation and large crystals are obtained after 10 s treatment in MA atmosphere. It enhances the light absorption, and increases the recombination lifetime. Ultimately, the power conversion efficiency (PCE of 15.3% for the FTO/TiO2/MAPbI3/spiro-OMeTAD/Ag planar architecture solar cells is achieved in combination with this post-treatment method. It represents a 40% improvement in PCE compared to the best control cell. Moreover, the whole post-treatment process is simple and cheap, which only requires some CH3NH2 solution in absolute ethanol. It is beneficial to control the reaction rate by changing the volume of the solution. Therefore, we are convinced that the post-treatment method is a valid and essential approach for the fabrication of high-efficiency perovskite solar cells.

  17. Synthesis, structure and total conductivity of A-site doped LaTiO{sub 3−δ} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Bradha, M. [Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore 641 004, TN (India); Hussain, S.; Chakravarty, Sujay [UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603 104, TN (India); Amarendra, G. [UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603 104, TN (India); Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Ashok, Anuradha, E-mail: anu.machina@gmail.com [Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore 641 004, TN (India)

    2015-03-25

    Highlights: • A-site divalent alkaline earth metal doped LaTiO{sub 3−δ} perovskites were synthesised by sol–gel method. • Structural studies revealed no change in crystal symmetry but change in cell dimensions after doping. • After doping divalent cations in A-site, an enhancement in total conductivity was observed in LaTiO{sub 3−δ}. • Temperature dependent electrical property was observed in all synthesised perovskites. - Abstract: Oxygen deficient perovskites LaTiO{sub 3−δ} and La{sub 0.8}A{sub 0.2}TiO{sub 3−δ} (A = Ba, Sr, Ca) were synthesized by sol–gel method. The effect of divalent dopants on microstructure is investigated in detail using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The oxidation states of La{sup 3+} and Ti{sup 3+} ions have been deduced using X-ray Photoelectron Spectroscopy (XPS). Impedance spectroscopy was used to analyze the total conductivity, an increase in conductivity was observed after doping in the A-site with divalent cations Ba, Ca and Sr. Among the investigated perovskites La{sub 0.8}Ca{sub 0.2}TiO{sub 3−δ} exhibited the maximum conductivity of 1.22 × 10{sup −2} S/cm in air atmosphere at 650 °C.

  18. CaCu3Ti4O12: A Bifunctional Perovskite Electrocatalyst for Oxygen Evolution and Reduction Reaction in Alkaline Medium

    International Nuclear Information System (INIS)

    Kushwaha, H.S.; Halder, Aditi; Thomas, P.; Vaish, Rahul

    2017-01-01

    Highlights: •A cost effective double perovskite CaCu 3 Ti 4 O 12 have been synthesized using oxalate precursor method. •CCTO electrocatalyst exhibit enhanced bifunctional electrocatalytic activities. •CCTO electrocatalyst have lower overpotential and higher mass activity as compared to noble metal oxide and well-known perovskite catalysts. •Electrochemical impedance spectroscopy investigations of oxygen reactions on perovskite surfaces. -- Abstract: Perovskite oxides are prominent materials as the bifunctional electrocatalysts for both oxygen reduction/evolution reactions (ORR/OER) for the electrochemical energy conversion and storage using regenerative fuel cells and rechargeable metal-air batteries. In this work, a quadruple perovskite CaCu 3 Ti 4 O 12 has been synthesized oxalate precursor route. X-ray diffraction pattern shows phase purity of the synthesized electrocatalyst. The synthesized CCTO electrocatalyst have crystallite size of 26 nm. Electrochemical investigations reveal that CCTO exhibit efficient catalytic activity. More interestingly, an extremely high OER activity is observed for CCTO electrocatalysts which is found superior than similar class of perovskites. Additionally, CCTO shows efficient ORR activity with an onset potential of 0.83 V which is better than that of Pt/C catalyst (≈0.94 V). These results demonstrate the significant potential of CCTO perovskite as a bifunctional electrode material for alkaline fuel cells and metal-air batteries.

  19. Generalized trends in the formation energies of perovskite oxides

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Calle-Vallejo, Federico; Mogensen, Mogens Bjerg

    2013-01-01

    Generalized trends in the formation energies of several families of perovskite oxides (ABO3) and plausible explanations to their existence are provided in this study through a combination of DFT calculations, solid-state physics analyses and simple physical/chemical descriptors. The studied...... elements at the A site of perovskites comprise rare-earth, alkaline-earth and alkaline metals, whereas 3d and 5d metals were studied at the B site. We also include ReO3-type compounds, which have the same crystal structure of cubic ABO3 perovskites except without A-site elements. From the observations we...... extract the following four conclusions for the perovskites studied in the present paper: for a given cation at the B site, (I) perovskites with cations of identical oxidation state at the A site possess close formation energies; and (II) perovskites with cations of different oxidation states at the A site...

  20. Tracking the formation of methylammonium lead triiodide perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lijia, E-mail: ljliu@suda.edu.cn, E-mail: jmcleod@suda.edu.cn; McLeod, John A., E-mail: ljliu@suda.edu.cn, E-mail: jmcleod@suda.edu.cn; Wang, Rongbin; Shen, Pengfei; Duhm, Steffen [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, 199 Ren' ai Road, Suzhou, Jiangsu 215123 (China)

    2015-08-10

    The formation mechanism of perovskite methylammonium lead triiodide (CH{sub 3}NH{sub 3}PbI{sub 3}) was studied with in situ X-ray photoelectron spectroscopy (XPS) on successive depositions of thermally evaporated methylammonium iodide (CH{sub 3}NH{sub 3}I) on a lead iodide (PbI{sub 2}) film. This deposition method mimics the “two-step” synthesis method commonly used in device fabrication. We find that several competing processes occur during the formation of perovskite CH{sub 3}NH{sub 3}PbI{sub 3}. Our most important finding is that during vapour deposition of CH{sub 3}NH{sub 3}I onto PbI{sub 2}, at least two carbon species are present in the resulting material, while only one nitrogen species is present. This suggests that CH{sub 3}NH{sub 3}I can dissociate during the transition to a perovskite phase, and some of the resulting molecules can be incorporated into the perovskite. The effect of partial CH{sub 3}NH{sub 3} substitution with CH{sub 3} was evaluated, and electronic structure calculations show that CH{sub 3} defects would impact the photovoltaic performance in perovskite solar cells. The possibility that not all A sites in the APbI{sub 3} perovskite are occupied by CH{sub 3}NH{sub 3} is therefore an important consideration when evaluating the performance of organometallic trihalide solar cells synthesized using typical approaches.

  1. Slow-Photon-Effect-Induced Photoelectrical-Conversion Efficiency Enhancement for Carbon-Quantum-Dot-Sensitized Inorganic CsPbBr3 Inverse Opal Perovskite Solar Cells.

    Science.gov (United States)

    Zhou, Shujie; Tang, Rui; Yin, Longwei

    2017-11-01

    All-inorganic cesium lead halide perovskite is suggested as a promising candidate for perovskite solar cells due to its prominent thermal stability and comparable light absorption ability. Designing textured perovskite films rather than using planar-architectural perovskites can indeed optimize the optical and photoelectrical conversion performance of perovskite photovoltaics. Herein, for the first time, this study demonstrates a rational strategy for fabricating carbon quantum dot (CQD-) sensitized all-inorganic CsPbBr 3 perovskite inverse opal (IO) films via a template-assisted, spin-coating method. CsPbBr 3 IO introduces slow-photon effect from tunable photonic band gaps, displaying novel optical response property visible to naked eyes, while CQD inlaid among the IO frameworks not only broadens the light absorption range but also improves the charge transfer process. Applied in the perovskite solar cells, compared with planar CsPbBr 3 , slow-photon effect of CsPbBr 3 IO greatly enhances the light utilization, while CQD effectively facilitates the electron-hole extraction and injection process, prolongs the carrier lifetime, jointly contributing to a double-boosted power conversion efficiency (PCE) of 8.29% and an increased incident photon-to-electron conversion efficiency of up to 76.9%. The present strategy on CsPbBr 3 IO to enhance perovskite PCE can be extended to rationally design other novel optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-15

    In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.

  3. Photostriction of CH3NH3PbBr3 Perovskite Crystals

    KAUST Repository

    Wei, Tzu-Chiao

    2017-07-17

    Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

  4. Sulfide perovskites for solar energy conversion applications: computational screening and synthesis of the selected compound LaYS3

    DEFF Research Database (Denmark)

    Kuhar, Korina; Crovetto, Andrea; Pandey, Mohnish

    2017-01-01

    of ternary sulfides followed by synthesis and confirmation of the properties of one of the most promising materials. The screening focusses on materials with ABS3 composition taking both perovskite and non-perovskite structures into consideration, and the material selection is based on descriptors...

  5. Low-Dimensional Organic-Inorganic Halide Perovskite: Structure, Properties, and Applications.

    Science.gov (United States)

    Misra, Ravi K; Cohen, Bat-El; Iagher, Lior; Etgar, Lioz

    2017-10-09

    Three-dimensional (3 D) perovskite has attracted a lot of attention owing to its success in photovoltaic (PV) solar cells. However, one of its major crucial issues lies in its stability, which has limited its commercialization. An important property of organic-inorganic perovskite is the possibility of forming a layered material by using long organic cations that do not fit into the octahedral cage. These long organic cations act as a "barrier" that "caps" 3 D perovskite to form the layered material. Controlling the number of perovskite layers could provide a confined structure with chemical and physical properties that are different from those of 3 D perovskite. This opens up a whole new batch of interesting materials with huge potential for optoelectronic applications. This Minireview presents the synthesis, properties, and structural orientation of low-dimensional perovskite. It also discusses the progress of low-dimensional perovskite in PV solar cells, which, to date, have performance comparable to that of 3 D perovskite but with enhanced stability. Finally, the use of low-dimensional perovskite in light-emitting diodes (LEDs) and photodetectors is discussed. The low-dimensional perovskites are promising candidates for LED devices, mainly because of their high radiative recombination as a result of the confined low-dimensional quantum well. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Chemical vapor deposition and electric characterization of perovskite oxides LaMO3 (M=Co, Fe, Cr and Mn) thin films

    International Nuclear Information System (INIS)

    Ngamou, Patrick Herve Tchoua; Bahlawane, Naoufal

    2009-01-01

    Oxides with a perovskite structure are important functional materials often used for the development of modern devices. In view of extending their applicability, it is necessary to efficiently control their growth as thin films using technologically relevant synthesis methods. Pulsed spray evaporation CVD was used to grow several perovskite-type oxides on planar silicon substrates at temperatures ranging from 500 to 700 deg. C. The optimization of the process control parameters allows the attainment of the perovskite structure as a single phase. The electrical characterization using the temperature-dependent conductivity and thermopower indicates the p-type conduction of the grown films and shows a decreasing concentration of the charge carrier, mobility and band gap energy in the sequence LaCoO 3 >LaMnO 3 >LaCrO 3 >LaFeO 3 . The investigation of the electric properties of the obtained perovskite thin films shows the versatility of CVD as a method for the development of innovative devices. - Graphical abstract: We report a single step deposition of perovskite thin films LaMO 3 (M: Co, Mn, Cr, Fe) using pulsed spray evaporation chemical vapor deposition. Electrical and thermopower properties, similar to these of bulk materials, could promote the development of modern thermoelectric devices based on thin films technology.

  7. Vapor and healing treatment for CH3NH3PbI3-xClx films toward large-area perovskite solar cells

    Science.gov (United States)

    Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A.; Bouhadana, Yaniv; Zaban, Arie

    2016-03-01

    Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm2). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (Voc, Jsc, Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ~100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a ``healing effect'' to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method.Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non

  8. Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO3

    International Nuclear Information System (INIS)

    Dixon, Charlotte A.L.; Kavanagh, Christopher M.; Knight, Kevin S.; Kockelmann, Winfried; Morrison, Finlay D.; Lightfoot, Philip

    2015-01-01

    The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO 3 has been studied in detail by powder neutron diffraction in the temperature range 253 . However, an unexpected behavior is seen in the nature of the intra-octahedral distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound. - Graphical abstract: The unusual thermal evolution of lattice metrics in the perovskite LaFeO 3 is rationalized from a detailed powder neutron diffraction study. - Highlights: • Crystal structure of the perovskite LaFeO 3 studied in detail by powder neutron diffraction. • Unusual thermal evolution of lattice metrics rationalized. • Contrasting behavior to Bi-doped LaFeO 3 . • Octahedral distortion/tilt parameters explain unusual a and c lattice parameter behavior

  9. High pressure Moessbauer spectroscopy of perovskite iron oxide

    International Nuclear Information System (INIS)

    Nasu, Saburo; Suenaga, Tomoya; Morimoto, Shotaro; Kawakami, Takateru; Kuzushita, Kaori; Takano, Mikio

    2003-01-01

    High-pressure 57 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO 3 , CaFeO 3 and La 1/3 Sr 2/3 O 3 . The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  10. Hexamethylenetetramine-mediated growth of grain-boundary-passivation CH3NH3PbI3 for highly reproducible and stable perovskite solar cells

    Science.gov (United States)

    Zheng, Yan-Zhen; Li, Xi-Tao; Zhao, Er-Fei; Lv, Xin-Ding; Meng, Fan-Li; Peng, Chao; Lai, Xue-Sen; Huang, Meilan; Cao, Guozhong; Tao, Xia; Chen, Jian-Feng

    2018-02-01

    Simultaneously achieving the long-term device stability and reproducibility has proven challenging in perovskite solar cells because solution-processing produced perovskite film with grain boundary is sensitive to moisture. Herein, we develop a hexamethylenetetramine (HMTA)-mediated one-step solution-processing deposition strategy that leads to the formation of high-purity and grain-boundary-passivation CH3NH3PbI3 film and thereby advances cell optoelectronic performance. Through morphological and structural characterizations and theoretical calculations, we demonstrate that HMTA fully occupies the moisture-exposed surface to build a bridge across grain boundary and coordinates with Pb ions to inhibit the formation of detrimental PbI2. Such HMTA-mediated grown CH3NH3PbI3 films achieves a decent augmentation of power conversion efficiency (PCE) from 12.70% to 17.87%. A full coverage of PbI2-free CH3NH3PbI3 surface on ZnO also boosts the device's stability and reproducibility.

  11. Characterization of 2024-T3: An aerospace aluminum alloy

    International Nuclear Information System (INIS)

    Huda, Zainul; Taib, Nur Iskandar; Zaharinie, Tuan

    2009-01-01

    The 2024-T3 aerospace aluminum alloy, reported in this investigation, was acquired from a local aerospace industry: Royal Malaysian Air Force (RMAF). The heat treatable 2024-T3 aluminum alloy has been characterized by use of modern metallographic and material characterization techniques (e.g. EPMA, SEM). The microstructural characterization of the metallographic specimen involved use of an optical microscope linked with a computerized imaging system using MSQ software. The use of EPMA and electron microprobe elemental maps enabled us to detect three types of inclusions: Al-Cu, Al-Cu-Fe-Mn, and Al-Cu-Fe-Si-Mn enriched regions. In particular, the presence of Al 2 CuMg (S-phase) and the CuAl 2 (θ') phases indicated precipitation strengthening in the aluminum alloy

  12. High-pressure crystal growth and electromagnetic properties of 5d double-perovskite Ca3OsO6

    International Nuclear Information System (INIS)

    Feng, Hai Luke; Shi, Youguo; Guo, Yanfeng; Li, Jun; Sato, Akira; Sun, Ying; Wang, Xia; Yu, Shan; Sathish, Clastin I.; Yamaura, Kazunari

    2013-01-01

    Single crystals of the osmium-containing compound Ca 3 OsO 6 have been successfully grown under high-pressure conditions, for the first time. The crystal structure of Ca 3 OsO 6 were characterized as an ordered double-perovskite structure of space group P2 1 /n with the Ca and Os atoms being fully ordered at the perovskite B-site. The electromagnetic analysis shows that the crystal exhibits a semiconductor-like behavior below 300 K and undergoes an antiferromagnetic transition at 50 K. - Graphical Abstract: Schematic image of crystal structure of Ca 3 OsO 6 as determined by X-ray diffraction, where the gray and black octahedrons are occupied by Ca and Os, respectively. Top inset reveals an optic image of a typical Ca 3 OsO 6 single crystal. Highlights: ► Single crystals of Ca 3 OsO 6 have been successfully grown under high-pressure. ► Ca 3 OsO 6 crystalizes into an ordered double-perovskite structure. ► The Ca 3 OsO 6 undergoes an antiferromagnetic transition at 50 K

  13. Low Cost CaTiO3 Perovskite Synthesized from Scallop (Anadara granosa) Shell as Antibacterial Ceramic Material

    Science.gov (United States)

    Fatimah, Is; Nur Ilahi, Rico; Pratami, Rismayanti

    2018-01-01

    Research on perovskite CaTiO3 synthesis from scallop (Anadara granosa) shell and its test as material for antibacterial ceramic application have been conducted. The synthesis was performed by calcium extraction from the scallop shell followed by solid-solid reaction of obtained calcium with TiO2. Physicochemical character of the perovskite wasstudied by measurement of crystallinity using x-ray diffraction (XRD), diffuse-reflectance UV Visible spectrophotometry, scanning electrone microscope-energy dispersive x-ray (SEM-EDX) and Fourier-Transform InfraRed. Considering the future application of the perovskite as antibacterial agent, laboratory test of the peroskite as material in antibacterial ceramic preparation was also conducted. Result of research indicated that perovskite formation was obtained and the material demonstrated photocatalytic activity as identified by band gap energy (Eg) value. The significant activity was also reflected by the antibacterial action of formed ceramic.

  14. Universal Approach toward Hysteresis-Free Perovskite Solar Cell via Defect Engineering.

    Science.gov (United States)

    Son, Dae-Yong; Kim, Seul-Gi; Seo, Ja-Young; Lee, Seon-Hee; Shin, Hyunjung; Lee, Donghwa; Park, Nam-Gyu

    2018-01-31

    Organic-inorganic halide perovskite is believed to be a potential candidate for high efficiency solar cells because power conversion efficiency (PCE) was certified to be more than 22%. Nevertheless, mismatch of PCE due to current density (J)-voltage (V) hysteresis in perovskite solar cells is an obstacle to overcome. There has been much lively debate on the origin of J-V hysteresis; however, effective methodology to solve the hysteric problem has not been developed. Here we report a universal approach for hysteresis-free perovskite solar cells via defect engineering. A severe hysteresis observed from the normal mesoscopic structure employing TiO 2 and spiro-MeOTAD is almost removed or does not exist upon doping the pure perovskites, CH 3 NH 3 PbI 3 and HC(NH 2 ) 2 PbI 3 , and the mixed cation/anion perovskites, FA 0.85 MA 0.15 PbI 2.55 Br 0.45 and FA 0.85 MA 0.1 Cs 0.05 PbI 2.7 Br 0.3 , with potassium iodide. Substantial reductions in low-frequency capacitance and bulk trap density are measured from the KI-doped perovskite, which is indicative of trap-hysteresis correlation. A series of experiments with alkali metal iodides of LiI, NaI, KI, RbI and CsI reveals that potassium ion is the right element for hysteresis-free perovskite. Theoretical studies suggest that the atomistic origin of the hysteresis of perovskite solar cells is not the migration of iodide vacancy but results from the formation of iodide Frenkel defect. Potassium ion is able to prevent the formation of Frenkel defect since K + energetically prefers the interstitial site. A complete removal of hysteresis is more pronounced at mixed perovskite system as compared to pure perovskites, which is explained by lower formation energy of K interstitial (-0.65 V for CH 3 NH 3 PbI 3 vs -1.17 V for mixed perovskite). The developed KI doping methodology is universally adapted for hysteresis-free perovskite regardless of perovskite composition and device structure.

  15. Material Exchange Property of Organo Lead Halide Perovskite with Hole-Transporting Materials

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2015-10-01

    Full Text Available Using X-ray diffraction (XRD, it was confirmed that the deposition of hole-transporting materials (HTM on a CH3NH3PbI3 perovskite layer changed the CH3NH3PbI3 perovskite crystal, which was due to the material exchanging phenomena between the CH3NH3PbI3 perovskite and HTM layers. The solvent for HTM also changed the perovskite crystal. In order to suppress the crystal change, doping by chloride ion, bromide ion and 5-aminovaleric acid was attempted. However, the doping was unable to stabilize the perovskite crystal against HTM deposition. It can be concluded that the CH3NH3PbI3 perovskite crystal is too soft and flexible to stabilize against HTM deposition.

  16. Conducting tin halides with a layered organic-based perovskite structure

    Science.gov (United States)

    Mitzi, D. B.; Feild, C. A.; Harrison, W. T. A.; Guloy, A. M.

    1994-06-01

    THE discovery1 of high-temperature superconductivity in layered copper oxide perovskites has generated considerable fundamental and technological interest in this class of materials. Only a few other examples of conducting layered perovskites are known; these are also oxides such as (La1-xSrx)n+1 MnnO3n+1 (ref. 2), Lan+1NinO3n+1 (ref. 3) and Ban+1PbnO3n+1 (ref. 4), all of which exhibit a trend from semiconducting to metallic behaviour with increasing number of perovskite layers (n). We report here the synthesis of a family of organic-based layered halide perovskites, (C4H9NH3)2(CH3NH3)n-1Snnl3n+1 which show a similar transition from semiconducting to metallic behaviour with increasing n. The incorporation of an organic modulation layer between the conducting tin iodide sheets potentially provides greater flexibility for tuning the electrical properties of the perovskite sheets, and we suggest that such an approach will prove valuable for exploring the range of transport properties possible with layered perovskites.

  17. Ceramic materials on perovskite-type structure for electronic applications

    International Nuclear Information System (INIS)

    Surowiak, Z.

    2003-01-01

    Ceramic materials exhibiting the perovskite-type structure constitute among others, resource base for many fields of widely understood electronics (i.e., piezoelectronics, accustoelectronics, optoelectronics, computer science, tele- and radioelectronics etc.). Most often they are used for fabrication of different type sensors (detectors), transducers, ferroelectric memories, limiters of the electronic current intensity, etc., and hence they are numbered among so-called intelligent materials. Prototype structure of this group of materials is the structure of the mineral called perovskite (CaTiO 3 ). By means of right choice of the chemical composition of ABO 3 and deforming the regular perovskite structure (m3m) more than 5000 different chemical compounds and solid solutions exhibiting the perovskite-type structure have been fabricated. The concept of perovskite functional ceramics among often things ferroelectric ceramics, pyroelectric ceramics, piezoelectric ceramics, electrostrictive ceramics, posistor ceramics, superconductive ceramics and ferromagnetic ceramics. New possibilities of application of the perovskite-type ceramics are opened by nanotechnology. (author)

  18. Water-assisted size and shape control of CsPbBr3 perovskite nanocrystals

    International Nuclear Information System (INIS)

    Zhang, Xiaoyu; Bai, Xue; Wu, Hua; Zhang, Xiangtong; Sun, Chun; Zhang, Yu; Zhang, Wei; Zheng, Weitao; Yu, William W.; Rogach, Andrey L.

    2018-01-01

    Lead-halide perovskites are well known to decompose rapidly when exposed to polar solvents, such as water. Contrary to this common-place observation, we have found that through introducing a suitable minor amount of water into the reaction mixture, we can synthesize stable CsPbBr 3 nanocrystals. The size and the crystallinity, and as a result the band gap tunability of the strongly emitting CsPbBr 3 nanocrystals correlate with the water content. Suitable amounts of water change the crystallization environment, inducing the formation of differently shaped perovskites, namely spherical NCs, rectangular nanoplatelets, or nanowires. Bright CsPbBr 3 nanocrystals with the photoluminescence quantum yield reaching 90 % were employed for fabrication of inverted hybrid inorganic/organic light-emitting devices, with the peak luminance of 4428 cd m -2 and external quantum yield of 1.7 %. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Plasmonic Perovskite Light-Emitting Diodes Based on the Ag-CsPbBr3 System.

    Science.gov (United States)

    Zhang, Xiaoli; Xu, Bing; Wang, Weigao; Liu, Sheng; Zheng, Yuanjin; Chen, Shuming; Wang, Kai; Sun, Xiao Wei

    2017-02-08

    The enhanced luminescence through semiconductor-metal interactions suggests the great potential of device performance improvement via properly tailored plasmonic nanostructures. Surface plasmon enhanced electroluminescence in an all-inorganic CsPbBr 3 perovskite light-emitting diode (LED) is fabricated by decorating the hole transport layer with the synthesized Ag nanorods. An increase of 42% and 43.3% in the luminance and efficiency is demonstrated for devices incorporated with Ag nanorods. The device with Ag introduction indicates identical optoelectronic properties to the controlled device without Ag nanostructures. The increased spontaneous emission rate caused by the Ag-induced plasmonic near-field effect is responsible for the performance enhancement. Therefore, the plasmonic Ag-CsPbBr 3 nanostructure studied here provides a novel strategy on the road to the future development of perovskite LEDs.

  20. Stability and carrier mobility of organic-inorganic hybrid perovskite CH3NH3PbI3 in two-dimensional limit

    Science.gov (United States)

    Huang, Kui; Lai, Kang; Yan, Chang-Lin; Zhang, Wei-Bing

    2017-10-01

    Recently, atomically thin organic-inorganic hybrid perovskites have been synthesized experimentally, which opens up new opportunities for exploring their novel properties in the 2D limit. Based on the comparative density functional theory calculation with and without spin-orbit coupling effects, the stability, electronic structure, and carrier mobility of the two-dimensional organic-inorganic hybrid perovskites MAPbI3 (MA = CH3NH3) have been investigated systemically. Two single-unit-cell-thick 2D MAPbI3 terminated by PbI2 and CH3NH3I are constructed, and their thermodynamic stabilities are also evaluated using the first-principles constrained thermodynamics method. Our results indicate that both 2D MAPbI3 with different terminations can be stable under certain conditions and have a suitable direct bandgap. Moreover, they are also found to have termination-dependent band edge and carrier mobility. The acoustic-phonon-limited carrier mobilities estimated using the deformation theory and effective mass approximation are on the order of thousands of square centimeters per volt per second and also highly anisotropic. These results indicate that 2D MAPbI3 are competitive candidates for low-dimensional photovoltaic applications.

  1. Doping Lanthanide into Perovskite Nanocrystals: Highly Improved and Expanded Optical Properties.

    Science.gov (United States)

    Pan, Gencai; Bai, Xue; Yang, Dongwen; Chen, Xu; Jing, Pengtao; Qu, Songnan; Zhang, Lijun; Zhou, Donglei; Zhu, Jinyang; Xu, Wen; Dong, Biao; Song, Hongwei

    2017-12-13

    Cesium lead halide (CsPbX 3 ) perovskite nanocrystals (NCs) have demonstrated extremely excellent optical properties and great application potentials in various optoelectronic devices. However, because of the anion exchange, it is difficult to achieve white-light and multicolor emission for practical applications. Herein, we present the successful doping of various lanthanide ions (Ce 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ , Er 3+ , and Yb 3+ ) into the lattices of CsPbCl 3 perovskite NCs through a modified hot-injection method. For the lanthanide ions doped perovskite NCs, high photoluminescence quantum yield (QY) and stable and widely tunable multicolor emissions spanning from visible to near-infrared (NIR) regions are successfully obtained. This work indicates that the doped perovskite NCs will inherit most of the unique optical properties of lanthanide ions and deliver them to the perovskite NC host, thus endowing the family of perovskite materials with excellent optical, electric, or magnetic properties.

  2. Characterization of 2024-T3: An aerospace aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huda, Zainul [Department of Mechanical Engineering, University of Malaya, Kuala Lumpur (Malaysia)], E-mail: drzainulhuda@hotmail.com; Taib, Nur Iskandar [Department of Geology, University of Malaya, Kuala Lumpur (Malaysia)], E-mail: ntaib@alumni.indiana.edu; Zaharinie, Tuan [Department of Mechanical Engineering, University of Malaya, Kuala Lumpur (Malaysia)], E-mail: rinie_3483@hotmail.com

    2009-02-15

    The 2024-T3 aerospace aluminum alloy, reported in this investigation, was acquired from a local aerospace industry: Royal Malaysian Air Force (RMAF). The heat treatable 2024-T3 aluminum alloy has been characterized by use of modern metallographic and material characterization techniques (e.g. EPMA, SEM). The microstructural characterization of the metallographic specimen involved use of an optical microscope linked with a computerized imaging system using MSQ software. The use of EPMA and electron microprobe elemental maps enabled us to detect three types of inclusions: Al-Cu, Al-Cu-Fe-Mn, and Al-Cu-Fe-Si-Mn enriched regions. In particular, the presence of Al{sub 2}CuMg (S-phase) and the CuAl{sub 2} ({theta}') phases indicated precipitation strengthening in the aluminum alloy.

  3. Carbon-Coated Perovskite BaMnO3 Porous Nanorods with Enhanced Electrocatalytic Perporites for Oxygen Reduction and Oxygen Evolution

    International Nuclear Information System (INIS)

    Xu, Yujiao; Tsou, Alvin; Fu, Yue; Wang, Jin; Tian, Jing-Hua; Yang, Ruizhi

    2015-01-01

    A thin carbon layer has been introduced to coat on the perovskite BaMnO 3 nanorods by a facile method, which exhibit significantly enhanced electrocatalytic activity for both the ORR and OER with excellent stability. - Highlights: • A non-rare-earth element based perovskite BaMnO 3 nanorods as an active electrocatalyst for the ORR and OER have been prepared and investigated for the first time. • A thin carbon-coating layer with thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity and the electrocatalytic activities of the bare perovskite for both ORR and OER. • The stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved dramatically with the help of carbon coating, especially for the OER process. - Abstract: Highly efficient, low-cost catalysts, especially with bifunctional electrocatalytic capabilities for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital for the wide commercialization of fuel cells and metal-air batteries. In this study, BaMnO 3 - a non-rare-earth element based perovskite nanorods have been prepared and investigated for the first time, and a thin carbon-coating with a thickness of approximately 10 nm has been successfully introduced to enhance the electrical conductivity of the bare perovskite. Electrochemical tests reveal that bare BaMnO 3 nanorods exhibit very good catalytic activity. More interestingly, a remarkably enhanced ORR activity for the perovskite BaMnO 3 nanorods was observed after coating with a thin layer of carbon, which dominated with a direct four-electron pathway. Meanwhile, the OER process has also been enhanced extraordinarily with the carbon-coating, reaching a maximum of 14.8 mA cm −2 at 1.0 V (vs. Ag/AgCl), which is far superior to both the bare BaMnO 3 nanorods and commercial Pt/C (20 wt%) catalysts. Furthermore, the stabilities of bare BaMnO 3 nanorods for both ORR and OER have also been improved

  4. Perovskite-Based Solar Cells: Materials, Methods, and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Di Zhou

    2018-01-01

    Full Text Available A novel all-solid-state, hybrid solar cell based on organic-inorganic metal halide perovskite (CH3NH3PbX3 materials has attracted great attention from the researchers all over the world and is considered to be one of the top 10 scientific breakthroughs in 2013. The perovskite materials can be used not only as light-absorbing layer, but also as an electron/hole transport layer due to the advantages of its high extinction coefficient, high charge mobility, long carrier lifetime, and long carrier diffusion distance. The photoelectric power conversion efficiency of the perovskite solar cells has increased from 3.8% in 2009 to 22.1% in 2016, making perovskite solar cells the best potential candidate for the new generation of solar cells to replace traditional silicon solar cells in the future. In this paper, we introduce the development and mechanism of perovskite solar cells, describe the specific function of each layer, and focus on the improvement in the function of such layers and its influence on the cell performance. Next, the synthesis methods of the perovskite light-absorbing layer and the performance characteristics are discussed. Finally, the challenges and prospects for the development of perovskite solar cells are also briefly presented.

  5. Generalized trends in the formation energies of perovskite oxides.

    Science.gov (United States)

    Zeng, ZhenHua; Calle-Vallejo, Federico; Mogensen, Mogens B; Rossmeisl, Jan

    2013-05-28

    Generalized trends in the formation energies of several families of perovskite oxides (ABO3) and plausible explanations to their existence are provided in this study through a combination of DFT calculations, solid-state physics analyses and simple physical/chemical descriptors. The studied elements at the A site of perovskites comprise rare-earth, alkaline-earth and alkaline metals, whereas 3d and 5d metals were studied at the B site. We also include ReO3-type compounds, which have the same crystal structure of cubic ABO3 perovskites except without A-site elements. From the observations we extract the following four conclusions for the perovskites studied in the present paper: for a given cation at the B site, (I) perovskites with cations of identical oxidation state at the A site possess close formation energies; and (II) perovskites with cations of different oxidation states at the A site usually have quite different but ordered formation energies. On the other hand, for a given A-site cation, (III) the formation energies of perovskites vary linearly with respect to the atomic number of the elements at the B site within the same period of the periodic table, and the slopes depend systematically on the oxidation state of the A-site cation; and (IV) the trends in formation energies of perovskites with elements from different periods at the B site depend on the oxidation state of A-site cations. Since the energetics of perovskites is shown to be the superposition of the individual contributions of their constituent oxides, the trends can be rationalized in terms of A-O and B-O interactions in the ionic crystal. These findings reveal the existence of general systematic trends in the formation energies of perovskites and provide further insight into the role of ion-ion interactions in the properties of ternary compounds.

  6. Fast Postmoisture Treatment of Luminescent Perovskite Films for Efficient Light-Emitting Diodes.

    Science.gov (United States)

    Wang, Haoran; Li, Xiaomin; Yuan, Mingjian; Yang, Xuyong

    2018-04-01

    Despite the recent advances in the performance of perovskite light-emitting diodes (PeLEDs), the effects of water on the perovskite emissive layer and its electroluminescence are still unclear, even though it has been previously demonstrated that moisture has a significant impact on the quality of perovskite films in the fabrication process of perovskite solar cells and is a prerequisite for obtaining high-performance PeLEDs. Here, the effects of postmoisture on the luminescent CH 3 NH 3 PbBr 3 (MAPbBr 3 ) perovskite films are systematically investigated. It is found that postmoisture treatment can efficiently control the morphology and growth of perovskite films and only a fast moisture exposure at a 60% high relative humidity results in significantly improved crystallinity, carrier lifetime, and photoluminescence quantum yield of perovskite films. With the optimized moisture-treated perovskite films, a high-performance PeLED is fabricated, exhibiting a maximum current efficiency of 20.4 cd A -1 , which is an almost 20-fold enhancement when compared with perovskite films without moisture treatment. The results provide valuable insights into the moisture-assisted growth of luminescent perovskite films and will aid in the development of high-performance perovskite light-emitting devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Development of High Efficiency Four-Terminal Perovskite-Silicon Tandems

    Science.gov (United States)

    Duong, The Duc

    This thesis is concerned with the development of high efficiency four-terminal perovskite-silicon tandem solar cells with the potential to reduce the cost of solar energy. The work focuses on perovskite top cells and can be divided into three main parts: developing low parasitic absorption and efficient semi-transparent perovskite cells, doping perovskite materials with rubidium, and optimizing perovskite material's bandgap with quadruple-cation and mixed-halide. A further section investigates the light stability of optimized bandgap perovskite cells. In a four-terminal mechanically stacked tandem, the perovskite top cell requires two transparent contacts at both the front and rear sides. Through detailed optical and electrical power loss analysis of the tandem efficiency due to non-ideal properties of the two transparent contacts, optimal contact parameters in term of sheet resistance and transparency are identified. Indium doped tin oxide by sputtering is used for both two transparent contacts and their deposition parameters are optimized separately. The semi-transparent perovskite cell using MAPbI3 has an efficiency of more than 12% with less than 12% parasitic absorption and up to 80% transparency in the long wavelength region. Using a textured foil as anti-reflection coating, an outstanding average transparency of 84% in the long wavelength is obtained. The low parasitic absorption allows an opaque version of the semi-transparent perovskite cell to operate efficiently in a filterless spectrum splitting perovskite-silicon tandem configuration. To further enhance the performance of perovskite cells, it is essential to improve the quality of perovskite films. This can be achieved with mixed-perovskite FAPbI3/MAPbBr3. However, mixed-perovskite films normally contain small a small amount of a non-perovskite phase, which is detrimental for the cell performance. Rb-doping is found to eliminate the formation of the non-perovskite phase and enhance the crystallinity of

  8. Some aspects of solid state radioluminescence

    International Nuclear Information System (INIS)

    Wojtowicz, A.J.

    1999-01-01

    In this paper we review results of radioluminescence studies on two scintillator materials, LuAlO 3 and YAlO 3 , activated with Ce. The experiments include measurements of thermoluminescence, isothermal phosphorescence decays, scintillation light yield as function of temperature, and scintillation time profiles under gamma excitation. Experimental results are interpreted in the frame of a simple kinetic model that includes a number of electron traps. We have identified and characterized a number of deep and shallow traps and demonstrated that traps in LuAlO 3 :Ce are deeper than corresponding traps in YALO 3 :Ce. Unlike deep traps which are responsible for some scintillation light loss but otherwise do not have any impact on generation of scintillation light, shallow traps are shown to actively interfere with the process of radiative recombination via Ce ions. We demonstrate that shallow traps are responsible for some as yet unexplained observations including a higher room temperature light yield of YAlO 3 :Ce and its longer scintillation decay time, as well as a longer scintillation rise time in LuAlO 3 C e. (author)

  9. Photon Reabsorption in Mixed CsPbCl3:CsPbI3 Perovskite Nanocrystal Films for Light-Emitting Diodes

    KAUST Repository

    Davis, Nathaniel J. L. K.; de la Peñ a, Francisco J.; Tabachnyk, Maxim; Richter, Johannes M.; Lamboll, Robin D.; Booker, Edward P.; Wisnivesky Rocca Rivarola, Florencia; Griffiths, James T.; Ducati, Caterina; Menke, S. Matthew; Deschler, Felix; Greenham, Neil C.

    2017-01-01

    is significantly reduced. We investigate samples containing mixtures of perovskite nanocrystals with different compositions and study the resulting optical and electrical interactions. We report excitation transfer from CsPbCl3 to CsPbI3 in solution and within a

  10. Quantum confinement effect and exciton binding energy of layered perovskite nanoplatelets

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2018-02-01

    Full Text Available We report the preparation of monolayer (n = 1, few-layer (n = 2–5 and 3D (n = ∞ organic lead bromide perovskite nanoplatelets (NPLs by tuning the molar ratio of methylammonium bromide (MABr and hexadecammonium bromide (HABr. The absorption spectrum of the monolayer (HA2PbBr4 perovskite NPLs shows about 138 nm blue shift from that of 3D MAPbBr3 perovskites, which is attributed to strong quantum confinement effect. We further investigate the two-photon photoluminescence (PL of the NPLs and measure the exciton binding energy of monolayer perovskite NPLs using linear absorption and two-photon PL excitation spectroscopy. The exciton binding energy of monolayer perovskite NPLs is about 218 meV, which is far larger than tens of meV in 3D lead halide perovskites.

  11. All-perovskite transparent high mobility field effect using epitaxial BaSnO3 and LaInO3

    Directory of Open Access Journals (Sweden)

    Useong Kim

    2015-03-01

    Full Text Available We demonstrate an all-perovskite transparent heterojunction field effect transistor made of two lattice-matched perovskite oxides: BaSnO3 and LaInO3. We have developed epitaxial LaInO3 as the gate oxide on top of BaSnO3, which were recently reported to possess high thermal stability and electron mobility when doped with La. We measured the dielectric properties of the epitaxial LaInO3 films, such as the band gap, dielectric constant, and the dielectric breakdown field. Using the LaInO3 as a gate dielectric and the La-doped BaSnO3 as a channel layer, we fabricated field effect device structure. The field effect mobility of such device was higher than 90 cm2 V−1 s−1, the on/off ratio was larger than 107, and the subthreshold swing was 0.65 V dec−1. We discuss the possible origins for such device performance and the future directions for further improvement.

  12. Full coverage of perovskite layer onto ZnO nanorods via a modified sequential two-step deposition method for efficiency enhancement in perovskite solar cells

    Science.gov (United States)

    Ruankham, Pipat; Wongratanaphisan, Duangmanee; Gardchareon, Atcharawon; Phadungdhitidhada, Surachet; Choopun, Supab; Sagawa, Takashi

    2017-07-01

    Full coverage of perovskite layer onto ZnO nanorod substrates with less pinholes is crucial for achieving high-efficiency perovskite solar cells. In this work, a two-step sequential deposition method is modified to achieve an appropriate property of perovskite (MAPbI3) film. Surface treatment of perovskite layer and its precursor have been systematically performed and their morphologies have been investigated. By pre-wetting of lead iodide (PbI2) and letting it dry before reacting with methylammonium iodide (MAI) provide better coverage of perovskite film onto ZnO nanorod substrate than one without any treatment. An additional MAI deposition followed with toluene drop-casting technique on the perovskite film is also found to increase the coverage and enhance the transformation of PbI2 to MAPbI3. These lead to longer charge carrier lifetime, resulting in an enhanced power conversion efficiency (PCE) from 1.21% to 3.05%. The modified method could been applied to a complex ZnO nanorods/TiO2 nanoparticles substrate. The enhancement in PCE to 3.41% is observed. These imply that our introduced method provides a simple way to obtain the full coverage and better transformation to MAPbI3 phase for enhancement in performances of perovskite solar cells.

  13. High pressure Moessbauer spectroscopy of perovskite iron oxide

    CERN Document Server

    Nasu, S; Morimoto, S; Kawakami, T; Kuzushita, K; Takano, M

    2003-01-01

    High-pressure sup 5 sup 7 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO sub 3 , CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 O sub 3. The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO sub 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

  14. CHARACTERIZATION AND ALUMINUM DISSOLUTION DEMONSTRATION WITH A 3 LITER TANK 51H SAMPLE

    International Nuclear Information System (INIS)

    Hay, M; John Pareizs, J; Cj Bannochie, C; Michael Stone, M; Damon Click, D; Daniel McCabe, D

    2008-01-01

    A 3-liter sludge slurry sample was sent to SRNL for demonstration of a low temperature aluminum dissolution process. The sludge was characterized before and after the aluminum dissolution. Post aluminum dissolution sludge settling and the stability of the decanted supernate were also observed. The characterization of the as-received 3-liter sample of Tank 51H sludge slurry shows a typical high aluminum HM sludge. The XRD analysis of the dried solids indicates Boehmite is the predominant crystalline form of aluminum in the sludge solids. However, amorphous phases of aluminum present in the sludge would not be identified using this analytical technique. The low temperature (55 C) aluminum dissolution process was effective at dissolving aluminum from the sludge. Over the three week test, ∼42% of the aluminum was dissolved out of the sludge solids. The process appears to be selective for aluminum with no other metals dissolving to any appreciable extent. At the termination of the three week test, the aluminum concentration in the supernate had not leveled off indicating more aluminum could be dissolved from the sludge with longer contact times or higher temperatures. The slow aluminum dissolution rate in the test may indicate the dissolution of the Boehmite form of aluminum however; insufficient kinetic data exists to confirm this hypothesis. The aluminum dissolution process appears to have minimal impact on the settling rate of the post aluminum dissolution sludge. However, limited settling data were generated during the test to quantify the effects. The sludge settling was complete after approximately twelve days. The supernate decanted from the settled sludge after aluminum dissolution appears stable and did not precipitate aluminum over the course of several months. A mixture of the decanted supernate with Tank 11 simulated supernate was also stable with respect to precipitation

  15. The melting curve of MgSiO3 perovskite from molecular dynamics simulation

    International Nuclear Information System (INIS)

    Liu Zijiang; Zhang Cairong; Sun Xiaowei; Song Ting; Chu Yandong; Hu Jianbo

    2011-01-01

    The high-pressure melting curve of MgSiO 3 perovskite is simulated by using the constant temperature and pressure molecular dynamics method combined with effective pair potentials. The simulated structural properties of MgSiO 3 perovskite at ambient conditions reproduce the experiments and agree well with other theoretical works. The calculated equation of state is very successful in reproducing accurately the recent experimental data over wide pressure ranges. The predicted high-pressure melting curve is in good agreement with the recent experimental and the latest theoretical ones, and the melting curve up to the core-mantle boundary pressure, being very steep at lower pressures, rapidly flattens on increasing pressure. The present results also suggest the validity of the experimental data of Zerr and Boehler (1993 Science 262 553) and Shen and Lazor (1995 J. Geophys. Res. 100 17699).

  16. Li-rich anti-perovskite Li3OCl films with enhanced ionic conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Lu, XJ; Wu, G; Howard, JW; Chen, AP; Zhao, YS; Daemen, LL; Jia, QX

    2014-08-13

    Anti-perovskite solid electrolyte films were prepared by pulsed laser deposition, and their room-temperature ionic conductivity can be improved by more than an order of magnitude in comparison with its bulk counterpart. The cyclability of Li3OCl films in contact with lithium was evaluated using a Li/Li3OCl/Li symmetric cell, showing self-stabilization during cycling test.

  17. Synthesis of LaNiO3 perovskite type by chelating precursor method using EDTA: optimization of chelating content

    International Nuclear Information System (INIS)

    Santos, Jose Carlos dos; Pedrosa, Anne Michelle Garrido; Mesquita, Maria Eliane; Souza, Marcelo Jose Barros de

    2011-01-01

    The perovskites are strategic materials due their catalytic, electronic and magnetic properties. These properties are influenced by the calcination and synthesis conditions. In this work was carried out the synthesis of LaNiO 3 perovskite type by chelating precursor method using EDTA and also was studied the optimization of the EDTA content in the synthesis. The synthesized materials were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TG) and Infrared Spectroscopy (FTIR). In the optimization of the EDTA content the lowest ratio of metal / EDTA used was 1.0 / 0.1, where it was possible to obtain monophasic perovskite. (author)

  18. Thermodynamic origin of instability in hybrid halide perovskites

    Science.gov (United States)

    Tenuta, E.; Zheng, C.; Rubel, O.

    2016-11-01

    Degradation of hybrid halide perovskites under the influence of environmental factors impairs future prospects of using these materials as absorbers in solar cells. First principle calculations can be used as a guideline in search of new materials, provided we can rely on their predictive capabilities. We show that the instability of perovskites can be captured using ab initio total energy calculations for reactants and products augmented with additional thermodynamic data to account for finite temperature effects. Calculations suggest that the instability of CH3NH3PbI3 in moist environment is linked to the aqueous solubility of the CH3NH3I salt, thus making other perovskite materials with soluble decomposition products prone to degradation. Properties of NH3OHPbI3, NH3NH2PbI3, PH4PbI3, SbH4PbI3, CsPbBr3, and a new hypothetical SF3PbI3 perovskite are studied in the search for alternative solar cell absorber materials with enhanced chemical stability.

  19. Effects of hot airflow during spin-coating process on CH3NH3PbI3-xClx perovskite solar cells

    Science.gov (United States)

    Tanaka, Hiroki; Ohishi, Yuya; Oku, Takeo

    2018-01-01

    CH3NH3PbI3-xClx photovoltaic devices were fabricated, and the effects of hot airflow during spin-coating were investigated. Cubic perovskite crystals that is a high temperature phase were obtained by the hot airflow method. The conversion efficiencies of the devices prepared by the hot airflow were remained even after 56 days.

  20. High-pressure crystal growth and electromagnetic properties of 5d double-perovskite Ca3OsO6

    Science.gov (United States)

    Feng, Hai Luke; Shi, Youguo; Guo, Yanfeng; Li, Jun; Sato, Akira; Sun, Ying; Wang, Xia; Yu, Shan; Sathish, Clastin I.; Yamaura, Kazunari

    2013-05-01

    Single crystals of the osmium-containing compound Ca3OsO6 have been successfully grown under high-pressure conditions, for the first time. The crystal structure of Ca3OsO6 were characterized as an ordered double-perovskite structure of space group P21/n with the Ca and Os atoms being fully ordered at the perovskite B-site. The electromagnetic analysis shows that the crystal exhibits a semiconductor-like behavior below 300 K and undergoes an antiferromagnetic transition at 50 K.

  1. Light-Responsive Ion-Redistribution-Induced Resistive Switching in Hybrid Perovskite Schottky Junctions

    KAUST Repository

    Guan, Xinwei

    2017-11-23

    Hybrid Perovskites have emerged as a class of highly versatile functional materials with applications in solar cells, photodetectors, transistors, and lasers. Recently, there have also been reports on perovskite-based resistive switching (RS) memories, but there remain open questions regarding device stability and switching mechanism. Here, an RS memory based on a high-quality capacitor structure made of an MAPbBr3 (CH3NH3PbBr3) perovskite layer sandwiched between Au and indium tin oxide (ITO) electrodes is reported. Such perovskite devices exhibit reliable RS with an ON/OFF ratio greater than 103, endurance over 103 cycles, and a retention time of 104 s. The analysis suggests that the RS operation hinges on the migration of charged ions, most likely MA vacancies, which reversibly modifies the perovskite bulk transport and the Schottky barrier at the MAPbBr3/ITO interface. Such perovskite memory devices can also be fabricated on flexible polyethylene terephthalate substrates with high bendability and reliability. Furthermore, it is found that reference devices made of another hybrid perovskite MAPbI3 consistently exhibit filament-type switching behavior. This work elucidates the important role of processing-dependent defects in the charge transport of hybrid perovskites and provides insights on the ion-redistribution-based RS in perovskite memory devices.

  2. Water-Assisted Size and Shape Control of CsPbBr3 Perovskite Nanocrystals.

    Science.gov (United States)

    Zhang, Xiaoyu; Bai, Xue; Wu, Hua; Zhang, Xiangtong; Sun, Chun; Zhang, Yu; Zhang, Wei; Zheng, Weitao; Yu, William W; Rogach, Andrey L

    2018-03-19

    Lead-halide perovskites are well known to decompose rapidly when exposed to polar solvents, such as water. Contrary to this common-place observation, we have found that through introducing a suitable minor amount of water into the reaction mixture, we can synthesize stable CsPbBr 3 nanocrystals. The size and the crystallinity, and as a result the band gap tunability of the strongly emitting CsPbBr 3 nanocrystals correlate with the water content. Suitable amounts of water change the crystallization environment, inducing the formation of differently shaped perovskites, namely spherical NCs, rectangular nanoplatelets, or nanowires. Bright CsPbBr 3 nanocrystals with the photoluminescence quantum yield reaching 90 % were employed for fabrication of inverted hybrid inorganic/organic light-emitting devices, with the peak luminance of 4428 cd m -2 and external quantum yield of 1.7 %. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Layered Halide Double Perovskites Cs3+nM(II)nSb2X9+3n (M = Sn, Ge) for Photovoltaic Applications.

    Science.gov (United States)

    Tang, Gang; Xiao, Zewen; Hosono, Hideo; Kamiya, Toshio; Fang, Daining; Hong, Jiawang

    2018-01-04

    Over the past few years, the development of lead-free and stable perovskite absorbers with excellent performance has attracted extensive attention. Much effort has been devoted to screening and synthesizing this type of solar cell absorbers. Here, we present a general design strategy for designing the layered halide double perovskites Cs 3+n M(II) n Sb 2 X 9+3n (M = Sn, Ge) with desired photovoltaic-relevant properties by inserting [MX 6 ] octahedral layers, based on the principles of increased electronic dimensionality. Compared to Cs 3 Sb 2 I 9 , more suitable band gaps, smaller carrier effective masses, larger dielectric constants, lower exciton binding energies, and higher optical absorption can be achieved by inserting variable [SnI 6 ] or [GeI 6 ] octahedral layers into the [Sb 2 I 9 ] bilayers. Moreover, our results show that adjusting the thickness of inserted octahedral layers is an effective approach to tune the band gaps and carrier effective masses in a large range. Our work provides useful guidance for designing the promising layered antimony halide double perovskite absorbers for photovoltaic applications.

  4. Enhancing the efficiency of planar heterojunction perovskite solar cells via interfacial engineering with 3-aminopropyl trimethoxy silane hydrolysate

    Science.gov (United States)

    Wang, Ya-Qiong; Xu, Shou-Bin; Deng, Jian-Guo; Gao, Li-Zhen

    2017-12-01

    The interfacial compatibility between compact TiO2 and perovskite layers is critical for the performance of planar heterojunction perovskite solar cells (PSCs). A compact TiO2 film employed as an electron-transport layer (ETL) was modified using 3-aminopropyl trimethoxy silane (APMS) hydrolysate. The power conversion efficiency (PCE) of PSCs composed of an APMS-hydrolysate-modified TiO2 layer increased from 13.45 to 15.79%, which was associated with a significant enhancement in the fill factor (FF) from 62.23 to 68.04%. The results indicate that APMS hydrolysate can enhance the wettability of γ-butyrolactone (GBL) on the TiO2 surface, form a perfect CH3NH3PbI3 film, and increase the recombination resistance at the interface. This work demonstrates a simple but efficient method to improve the TiO2/perovskite interface that can be greatly beneficial for developing high-performance PSCs.

  5. Electrodeposition of organic-inorganic tri-halide perovskites solar cell

    Science.gov (United States)

    Charles, U. A.; Ibrahim, M. A.; Teridi, M. A. M.

    2018-02-01

    Perovskite (CH3NH3PbI3) semiconductor materials are promising high-performance light energy absorber for solar cell application. However, the power conversion efficiency of perovskite solar cell is severely affected by the surface quality of the deposited thin film. Spin coating is a low-cost and widely used deposition technique for perovskite solar cell. Notably, film deposited by spin coating evolves surface hydroxide and defeats from uncontrolled precipitation and inter-diffusion reaction. Alternatively, vapor deposition (VD) method produces uniform thin film but requires precise control of complex thermodynamic parameters which makes the technique unsuitable for large scale production. Most deposition techniques for perovskite require tedious surface optimization to improve the surface quality of deposits. Optimization of perovskite surface is necessary to significantly improve device structure and electrical output. In this review, electrodeposition of perovskite solar cell is demonstrated as a scalable and reproducible technique to fabricate uniform and smooth thin film surface that circumvents the need for high vacuum environment. Electrodeposition is achieved at low temperatures, supports precise control and optimization of deposits for efficient charge transfer.

  6. Large polarons in lead halide perovskites

    OpenAIRE

    Miyata, Kiyoshi; Meggiolaro, Daniele; Trinh, M. Tuan; Joshi, Prakriti P.; Mosconi, Edoardo; Jones, Skyler C.; De Angelis, Filippo; Zhu, X.-Y.

    2017-01-01

    Lead halide perovskites show marked defect tolerance responsible for their excellent optoelectronic properties. These properties might be explained by the formation of large polarons, but how they are formed and whether organic cations are essential remain open questions. We provide a direct time domain view of large polaron formation in single-crystal lead bromide perovskites CH3NH3PbBr3 and CsPbBr3. We found that large polaron forms predominantly from the deformation of the PbBr3 ? framewor...

  7. New Type of 2D Perovskites with Alternating Cations in the Interlayer Space, (C(NH 2 ) 3 )(CH 3 NH 3 ) n Pb n I 3n+1 : Structure, Properties, and Photovoltaic Performance

    Energy Technology Data Exchange (ETDEWEB)

    Soe, Chan Myae Myae; Stoumpos, Constantinos C.; Kepenekian, Mikaël; Traoré, Boubacar; Tsai, Hsinhan; Nie, Wanyi; Wang, Binghao; Katan, Claudine; Seshadri, Ram; Mohite, Aditya D.; Even, Jacky; Marks, Tobin J.; Kanatzidis, Mercouri G. (UCSB); (NWU); (LANL); (CNRS-UMR)

    2017-11-01

    We present the new homologous series (C(NH2)3)(CH3NH3)nPbnI3n+1 (n = 1, 2, 3) of layered 2D perovskites. Structural characterization by single-crystal X-ray diffraction reveals that these compounds adopt an unprecedented structure type, which is stabilized by the alternating ordering of the guanidinium and methylammonium cations in the interlayer space (ACI). Compared to the more common Ruddlesden–Popper (RP) 2D perovskites, the ACI perovskites have a different stacking motif and adopt a higher crystal symmetry. The higher symmetry of the ACI perovskites is expressed in their physical properties, which show a characteristic decrease of the bandgap with respect to their RP perovskite counterparts with the same perovskite layer thickness (n). The compounds show a monotonic decrease in the optical gap as n increases: Eg = 2.27 eV for n = 1 to Eg = 1.99 eV for n = 2 and Eg = 1.73 eV for n = 3, which show slightly narrower gaps compared to the corresponding RP perovskites. First-principles theoretical electronic structure calculations confirm the experimental optical gap trends suggesting that the ACI perovskites are direct bandgap semiconductors with wide valence and conduction bandwidths. To assess the potential of the ACI perovskites toward solar cell applications, we studied the (C(NH2)3)(CH3NH3)3Pb3I10 (n = 3) compound. Compact thin films from the (C(NH2)3)(CH3NH3)3Pb3I10 compound with excellent surface coverage can be obtained from the antisolvent dripping method. Planar photovoltaic devices from optimized ACI perovskite films yield a power-conversion-efficiency of 7.26% with a high open-circuit voltage of ~1 V and a striking fill factor of ~80%.

  8. Enhanced Crystallization by Methanol Additive in Anti-solvent for Achieving High-quality MAPbI3 Perovskite Films in Humid Atmosphere.

    Science.gov (United States)

    Yang, Fu; Kamarudin, Muhammad Akmal; Zhang, PuTao; Kapil, Gaurav; Ma, Tingli; Hayase, Shuzi

    2018-05-04

    Perovskite solar cells have attracted considerable attention owing to easy and low-cost solution manufacturing process with high power conversion efficiency. However, the fabrication process is usually performed inside glovebox to avoid the moisture, as organometallic halide perovskite is easily dissolved in water. In this study, we propose one-step fabrication of high-quality MAPbI3 perovskite films in 50 % RH humid ambient air by using diethyl ether as an anti-solvent and methanol as an additive into this anti-solvent. Because of the existence of methanol, the water molecules can be efficiently removed from the gaps of perovskite precursors and the perovskite film formation can be slightly controlled leading to pinhole-free and low roughness film. Concurrently, methanol can modify a proper DMSO ratio in the intermediate perovskite phase to regulate perovskite formation. Planar solar cells fabricated by using this method exhibited the best efficiency of 16.4 % with a reduced current density-voltage hysteresis. This efficiency value is approximately 160 % higher than the devices fabrication by using only diethyl ether treatment. From the impedance measurement, it is also found that the recombination reaction has been suppressed when the device prepared with additive anti-solvent way. This method presents a new path for controlling the growth and morphology of perovskite films in the humid climates and uncontrolled laboratories. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. CsPbBr3 Perovskites: Theoretical and Experimental Investigation on Water-Assisted Transition From Nanowire Formation to Degradation

    OpenAIRE

    Akbali, Baris; Topcu, Gokhan; Guner, Tugrul; Ozcan, Mehmet; Demir, Mustafa Muammer; Sahin, Hasan

    2018-01-01

    Recent advances in colloidal synthesis methods have led to increased research focus on halide perovskites. Due to highly ionic crystal structure of perovskite materials, stability issue pops up especially against polar solvents such as water. In this study, we investigate water-driven structural evolution of CsPbBr3 by performing experiments and state-of-the-art first-principles calculations. It is seen that while optical image shows the gradual degradation of yellowish-colored CsPbBr3 struct...

  10. A New Lead Iodide Perovskite based on Large Organic Cation for Solar Cell Application.

    Science.gov (United States)

    Ma, Chunqing; Shen, Dong; Lo, Ming Fai; Lee, Chun-Sing

    2018-06-06

    Methylammonium (CH3NH3+) and formamidinium ((NH2)2CH+) based lead iodide perovskites are currently the two commonly used organic-inorganic lead iodide perovskites for solar cell application. Till now, there is still no alternative organic cations, which can produce perovskites with bandgaps spanning the visible spectrum (i.e. solar cell application. Here, a new perovskite using large propane-1,3-diammonium cation (n-Pr(NH3)22+) with a chemical structure of (n-Pr(NH3)2)0.5PbI3 is demonstrated. X-ray diffraction (XRD) result shows that the new perovskite exhibits a three-dimensional (3D), tetragonal phase. The bandgap of the new perovskite is ~ 1.6 eV, which is desirable for photovoltaic application. A (n-Pr(NH3)2)0.5PbI3 perovskite solar cell (PSC) yields a power conversion efficiency (PCE) of 5.1%. More importantly, this new perovskite is composed of larger hydrophobic cation that provides a better moisture resistance compared to CH3NH3PbI3 perovskite. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Partial substitution of manganese with cerium in SrMnO_3 nano-perovskite catalyst. Effect of the modification on the catalytic combustion of dilute acetone

    International Nuclear Information System (INIS)

    Rezlescu, Nicolae; Rezlescu, Elena; Popa, Paul Dorin; Doroftei, Corneliu; Ignat, Maria

    2016-01-01

    Ultrafine SrMn_1_−_xCe_xO_3 (x = 0, 02) perovskites were prepared by self-combustion method and heat treatment at 1000 °C for 4 h. The structure and surface properties were investigated by X-ray powder diffraction, scanning electron microscopy (SEM), EDX spectroscopy, and BET analysis. The catalyst properties of the perovskite nanopowders were tested in the catalytic combustion of dilute acetone at atmospheric pressure. The results revealed that the partial substitution of Mn by Ce ions (x = 0.2) in perovskite structure of SrMnO_3 had significantly improved catalytic activity of the perovskite. The SrMn_0_._8Ce_0_,_2O_3 perovskite composition can be a good candidate for catalytic combustion of low concentration acetone (1–2‰ in air) at low temperatures. The acetone conversion over this catalyst exceeds 90% at 200 °C, whereas over SrMnO_3 it is only 50%. Compared with SrMnO_3, T_5_0 is decreased by 75 °C and T_9_0 is decreased by 70 °C. The enhancement of the catalytic activity at a Ce doping of 0.2 may be ascribed to smaller crystallite sizes, larger specific surface area and the presence of Ce and Mn cations with variable valence in the perovskite structure. - Highlights: • A non-conventional method was used to make nanostructured perovskite samples. • XRD study confirms perovskite structure and nanosize of crystallites. • EDX analyses confirm homogeneity and purity of the samples. • The catalytic testing was carried out in the flameless combustion of dilute acetone. • SrMn_0_._8Ce_0_._2O_3 perovskite can be a promising catalyst for acetone combustion at low temperature.

  12. Composition-dependent hot carrier relaxation dynamics in cesium lead halide (CsPbX{sub 3}, X=Br and I) perovskite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Heejae; Jung, Seok Il; Kim, Hyo Jin; Cha, Wonhee; Sim, Eunji; Kim, Dongho [Department of Chemistry, Yonsei University, Seoul (Korea, Republic of); Koh, Weon-Kyu [Device Laboratory, Samsung Advanced Institute of Technology, Suwon (Korea, Republic of); Kim, Jiwon [School of Integrated Technology and Underwood International College, Yonsei University, Incheon (Korea, Republic of)

    2017-04-03

    Cesium-based perovskite nanocrystals (NCs) have outstanding photophysical properties improving the performances of lighting devices. Fundamental studies on excitonic properties and hot-carrier dynamics in perovskite NCs further suggest that these materials show higher efficiencies compared to the bulk form of perovskites. However, the relaxation rates and pathways of hot-carriers are still being elucidated. By using ultrafast transient spectroscopy and calculating electronic band structures, we investigated the dependence of halide in Cs-based perovskite (CsPbX{sub 3} with X=Br, I, or their mixtures) NCs on the hot-carrier relaxation processes. All samples exhibit ultrafast (<0.6 ps) hot-carrier relaxation dynamics with following order: CsPbBr{sub 3} (310 fs)>CsPbBr{sub 1.5}I{sub 1.5} (380 fs)>CsPbI{sub 3} NC (580 fs). These result accounts for a reduced light emission efficiency of CsPbI{sub 3} NC compared to CsPbBr{sub 3} NC. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Identification and characterization of the intermediate phase in hybrid organic-inorganic MAPbI3 perovskite.

    Science.gov (United States)

    Guo, Xin; McCleese, Christopher; Kolodziej, Charles; Samia, Anna C S; Zhao, Yixin; Burda, Clemens

    2016-03-07

    Perovskite films were prepared using single step solution deposition at different annealing temperatures and annealing times. The crystal structure, phases and grain size were investigated with XRD, XPS and SEM/EDX. The prepared films show a typical orientation of tetragonal perovskite phase and a gradual transition at room temperature from the yellow intermediate phase to the black perovskite phase. Films with high purity were obtained by sintering at 100 °C. In addition, the chemical composition and crystal structure of intermediate phase were investigated in detail. FTIR, UV-vis and NMR spectra revealed the occurance of DMF complexes. Interestingly, the intermediate phase could be transformed to the black perovskite phase upon X-ray irradiation. In addition, the recovery of the aged perovskite films from a yellow intermediate phase back to the black perovskite was shown to be viable via heating and X-ray irradiation.

  14. Thermal engineering of lead-free nanostructured CH3NH3SnCl3 perovskite material for thin-film solar cell

    Science.gov (United States)

    Moyez, Sk Abdul; Roy, Subhasis

    2018-01-01

    Perovskite solar cell is a kind of revolutionary investigation in the field of renewable energy which is capable of mitigates the deficiencies of silicon solar cell and its uprising efficiency can bring blessing to society. The presence of lead (Pb) in perovskite solar cell can make worst and negative impact on environment and is not desirable for our society. In this paper, general plans are anticipated by replacement of Pb with tin (Sn) in open atmosphere to fabricate the CH3NH3SnCl3 photovoltaic cells in chlorine (Cl)-rich environment. Excess uses of Cl has positive influences on morphological growth of the film and it also suppresses the oxidation tendency of tin (Sn) with existing oxygen in atmosphere and maintains same chemical atmosphere as bulk. Various characterization tools like X-ray diffraction, scanning electron microscope (SEM) have been used to study the effect of annealing temperature on crystal stricture, phase formation, impurities, and morphologies of the film. Finally, photovoltaic performance was reported using the solar simulator under 1.5 sun illumination.

  15. Nanoscale charge localization induced by random orientations of organic molecules in hybrid perovskite CH3NH3PbI3

    Science.gov (United States)

    Ma, Jie; Wang, Lin-Wang

    2015-03-01

    Perovskite-based solar cells have achieved high solar-energy conversion efficiencies and attracted wide attentions nowadays. Despite the rapid progress in solar-cell devices, many fundamental issues of the hybrid perovskites have not been fully understood. Experimentally, it is well known that in CH3NH3PbI3, the organic molecules CH3NH3 are randomly orientated at the room temperature, but the impact of the random molecular orientation has not been investigated. Using linear-scaling ab-initiomethods, we have calculated the electronic structures of the tetragonal phase of CH3NH3PbI3 with randomly orientated organic molecules in large supercells up to ~20,000 atoms. Due to the dipole moment of the organic molecule, the random orientation creates a novel system with long-range potential fluctuations unlike alloys or other conventional disordered systems. We find that the charge densities of the conduction-band minimum and the valence-band maximum are localized separately in nanoscales due to the potential fluctuations. The charge localization causes electron-hole separation and reduces carrier recombination rates, which may contribute to the long carrier lifetime observed in experiments. We have also proposed a model to explain the charge localization.

  16. Tolerance factor rules for Sr1-x-yCaxBayMnO3 perovskites

    International Nuclear Information System (INIS)

    Dabrowski, B.; Chmaissem, O.; Mais, J.; Kolesnik, S.; Jorgensen, J.D.; Short, S.

    2003-01-01

    Synthesis of new perovskite Sr 1-x-y Ca x Ba y MnO 3-δ compounds is described in detail and dependence of their phase stability and structural distortions on the tolerance factor is discussed. Oxygen contents have been measured over extended temperature and composition ranges. Neutron powder diffraction was used to precisely measure the A-O and Mn-O bond lengths and derive accurate interatomic distances [Ca-O], [Sr-O], [Ba-O], and [Mn-O]. By using these parameters instead of tabulated ionic radii we have derived the functional dependence of the tolerance factor t=t(x,y,T,δ) on composition, temperature, and oxygen content. At a fixed oxygen content, the tolerance factor is an increasing function of temperature as a result of greater thermal expansion of the average bond relative to the bond. We find that the stability of the perovskite phase at high temperature is governed, as expected, by the magnitude of tolerance factor (t≤1) which can be adjusted by controlling the oxygen content 3-δ. This dependence of the tolerance factor on oxygen content and temperature can be utilized to design synthesis conditions for the controlled formation of the new, kinetically stable, perovskite phases

  17. Phase transformation of Ca-perovskite in MORB at D" region

    Science.gov (United States)

    Nishitani, N.; Ohtani, E.; Sakai, T.; Kamada, S.; Miyahara, M.; Hirao, N.

    2012-12-01

    Seismological studies indicate the presence of seismic anomalies in the Earth's deep interior. To investigate the anomaly, the physical property of the major minerals in lower mantle such as MgSiO3-perovskite, MgSiO3 post-perovskite and MgO periclase were studied well. Other candidate, CaSiO3 perovskite (Ca-perovskite) exists in peridotitic mantle and basaltic oceanic crust (mid-ocean ridge basalt; MORB). Previous studies indicate the abundance of Ca-perovskite is up to ~9 vol.% in the pyrolite mantle and ~24 vol.% in the MORB oceanic crust. However, the pressure range of previous works are still not enough to understand the D" region. In this study, natural MORB was compressed in double sided laser heated DAC. Au was used as a pressure maker and a laser absorber. NaCl was used as the thermal insulator and pressure medium. The phase relation of Ca-perovskite in MORB was investigated from 36 to 156 GPa and 300 to 2600 K by the in situ X-ray diffraction measurements at SPring-8 (BL10XU). The transition of Ca-perovskite from a tetragonal structure to a cubic structure occurred at about 1800 K up to about 100 GPa and below 1500 K at pressures above 100 GPa. This suggests that the tetragonal-cubic transition of Ca-perovskite could occur in MORB, associating with Al2O3 contents. The present results suggest that the seismic anomaly at D" layer could be caused by the transition in Ca-perovskite.

  18. Modulation of Charge Recombination in CsPbBr3 Perovskite Films with Electrochemical Bias

    KAUST Repository

    Scheidt, Rebecca A

    2017-11-13

    The charging of mesoscopic TiO2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr3 films deposited on a mesoscopic TiO2 film, we have succeeded in probing the influence of electrochemical bias on the charge carrier recombination process. The transient absorption spectroscopy experiments conducted at different applied potentials indicate a decrease in the charge carrier lifetimes of CsPbBr3 as we increase the potential from -0.6 V to + 0.6 V vs. Ag/AgCl. The charge carrier lifetime increased upon reversing the applied bias, thus indicating the reversibility of the photoresponse to charging effects. The ultrafast spectroelectrochemical experiments described here offer a convenient approach to probe the charging effects in perovskite solar cells.

  19. Modulation of Charge Recombination in CsPbBr3 Perovskite Films with Electrochemical Bias.

    Science.gov (United States)

    Scheidt, Rebecca A; Samu, Gergely F; Janáky, Csaba; Kamat, Prashant V

    2018-01-10

    The charging of a mesoscopic TiO 2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr 3 films deposited on a mesoscopic TiO 2 film, we have succeeded in probing the influence of electrochemical bias on the charge carrier recombination process. The transient absorption spectroscopy experiments conducted at different applied potentials indicate a decrease in the charge carrier lifetimes of CsPbBr 3 as we increase the potential from -0.6 to +0.6 V vs Ag/AgCl. The charge carrier lifetime increased upon reversing the applied bias, thus indicating the reversibility of the photoresponse to charging effects. The ultrafast spectroelectrochemical experiments described here offer a convenient approach to probe the charging effects in perovskite solar cells.

  20. Efficient perovskite light-emitting diodes featuring nanometre-sized crystallites

    Science.gov (United States)

    Xiao, Zhengguo; Kerner, Ross A.; Zhao, Lianfeng; Tran, Nhu L.; Lee, Kyung Min; Koh, Tae-Wook; Scholes, Gregory D.; Rand, Barry P.

    2017-01-01

    Organic-inorganic hybrid perovskite materials are emerging as highly attractive semiconductors for use in optoelectronics. In addition to their use in photovoltaics, perovskites are promising for realizing light-emitting diodes (LEDs) due to their high colour purity, low non-radiative recombination rates and tunable bandgap. Here, we report highly efficient perovskite LEDs enabled through the formation of self-assembled, nanometre-sized crystallites. Large-group ammonium halides added to the perovskite precursor solution act as a surfactant that dramatically constrains the growth of 3D perovskite grains during film forming, producing crystallites with dimensions as small as 10 nm and film roughness of less than 1 nm. Coating these nanometre-sized perovskite grains with longer-chain organic cations yields highly efficient emitters, resulting in LEDs that operate with external quantum efficiencies of 10.4% for the methylammonium lead iodide system and 9.3% for the methylammonium lead bromide system, with significantly improved shelf and operational stability.

  1. Water-Induced Dimensionality Reduction in Metal-Halide Perovskites

    KAUST Repository

    Turedi, Bekir; Lee, Kwangjae; Dursun, Ibrahim; Alamer, Badriah Jaber; Wu, Zhennan; Alarousu, Erkki; Mohammed, Omar F.; Cho, Namchul; Bakr, Osman

    2018-01-01

    . Here we employ water to directly transform films of the three-dimensional (3D) perovskite CsPbBr3 to stable two-dimensional (2D) perovskite-related CsPb2Br5. A sequential dissolution-recrystallization process governs this water induced transformation

  2. Luminescence of Mn{sup 4+} in the orthorhombic perovskite, LaGaO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, A.M., E-mail: srivastava@ge.com [GE Global Research, One Research Circle, Niskayuna, New York 12309 (United States); Camardello, S.J. [GE Global Research, One Research Circle, Niskayuna, New York 12309 (United States); Brik, M.G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, PL-42200 Czestochowa (Poland)

    2017-03-15

    The optical properties of Mn{sup 4+} (3d{sup 3}) in the orthorhombic perovskite, LaGaO{sub 3} are investigated. The Mn{sup 4+} energy levels are calculated using the exchange charge model of crystal-field theory. The calculated Mn{sup 4+} energy levels are in good agreement with the experimental spectroscopic data. The results of our calculations yield the crystal-field splitting and Racah parameters of Dq=1926 cm{sup −1}, B=780 cm{sup −1} and C=2878 cm{sup −1}, with C/B=3.7. The emission spectrum is assigned on the basis of the zero phonon line corresponding to the {sup 2}E{sub g}→{sup 4}A{sub 2g} transition and its vibrational sidebands. A comparative study of the variation in the crystal-field splitting and the Mn{sup 4+} {sup 2}E{sub g} energy level position in materials with the perovskite structure is also presented.

  3. New lithium-ion conducting perovskite oxides related to (Li, La)TiO3

    Indian Academy of Sciences (India)

    Unknown

    We describe the synthesis and lithium-ion conductivity of new perovskite-related oxides ... work on lithium-ion conducting perovskite oxides containing d0 cations. Keywords. ..... On the other hand, Nb/Ta compounds show a higher conductivity.

  4. Multiple-Stage Structure Transformation of Organic-Inorganic Hybrid Perovskite CH3NH3PbI3

    Science.gov (United States)

    Chen, Qiong; Liu, Henan; Kim, Hui-Seon; Liu, Yucheng; Yang, Mengjin; Yue, Naili; Ren, Gang; Zhu, Kai; Liu, Shengzhong; Park, Nam-Gyu; Zhang, Yong

    2016-07-01

    By performing spatially resolved Raman and photoluminescence spectroscopy with varying excitation wavelength, density, and data acquisition parameters, we achieve a unified understanding towards the spectroscopy signatures of the organic-inorganic hybrid perovskite, transforming from the pristine state (CH3NH3PbI3 ) to the fully degraded state (i.e., PbI2 ) for samples with varying crystalline domain size from mesoscopic scale (approximately 100 nm) to macroscopic size (centimeters), synthesized by three different techniques. We show that the hybrid perovskite exhibits multiple stages of structure transformation occurring either spontaneously or under light illumination, with exceptionally high sensitivity to the illumination conditions (e.g., power, illumination time, and interruption pattern). We highlight four transformation stages (stages I-IV, with stage I being the pristine state) along either the spontaneous or photoinduced degradation path exhibiting distinctly different Raman spectroscopy features at each stage, and point out that previously reported Raman spectra in the literature reflect highly degraded structures of either stage III or stage IV. Additional characteristic optical features of partially degraded materials under the joint action of spontaneous and photodegradation are also given. This study offers reliable benchmark results for understanding the intrinsic material properties and structure transformation of this unique category of hybrid materials, and the findings are pertinently important to a wide range of potential applications where the hybrid material is expected to function in greatly different environment and light-matter interaction conditions.

  5. Perovskite as a matrix for incorporation of long-lived radionuclides

    International Nuclear Information System (INIS)

    Chernyavskaya, N.E.; Ochkin, A.V.; Chizhevskaya, S.V.; Stefanovskij, S.V.

    1998-01-01

    SYNROC is titanate ceramics consisting mainly of zirconolite, perovskite, and hollandite, developed to immobilize high level waste. Perovskite is able to incorporate strontium, yttrium, and trivalent lanthanides and actinides. The main goal of the present work is leaching study of various radionuclides from perovskite. Samples of perovskite-rich ceramics were produced by cold pressing of oxide mixture followed by firing in resistive furnace at 1350 degC for 3 hours. For leaching tests, ceramic pellets were crushed and surface areas were measured using argon thermal desorption technique. Leach rate was measured by boiling in a Soxhlet apparatus for 5 hours. Leach rates in 0.1 M HNO 3 and NaCl solutions were measured by boiling with stirrer and reverse cooler. Leach rate was controlled with radioactive indicator technique. Density of the perovskite-rich ceramic samples prepared was about 75% of theoretical. From XRD examination, the target phase (perovskite) yield was found to be about 95 vol.%. Minor rutile (≤ 5 vol.%) was also present. Leach rate of 90 Sr from Sr-doped perovskites with specified composition Ca 1-x Sr x TiO 3 did not depend on x until certain x value. Leach rate of 90 Sr from control zirconolite sample was by one order of magnitude higher than from perovskite. Leach rates of 147 Pm, 238 Pu, and 241 Am from perovskite ceramics with nominal perovskite composition had the same order of magnitude (about 10 -4 g/(m 2 day)). Substitution of 5 at.% Ce for Ca and 5 at.% Al for Ti lowered leach rate of 238 Pu by a factor of 6. Leach rates of 90 Sr in 0.1 M HNO 3 and NaCl solutions were three and one orders of magnitude higher than in distilled water

  6. Nickel oxide electrode interlayer in CH3 NH3 PbI3 perovskite/PCBM planar-heterojunction hybrid solar cells.

    Science.gov (United States)

    Jeng, Jun-Yuan; Chen, Kuo-Cheng; Chiang, Tsung-Yu; Lin, Pei-Ying; Tsai, Tzung-Da; Chang, Yun-Chorng; Guo, Tzung-Fang; Chen, Peter; Wen, Ten-Chin; Hsu, Yao-Jane

    2014-06-25

    This study successfully demonstrates the application of inorganic p-type nickel oxide (NiOx ) as electrode interlayer for the fabrication of NiOx /CH3 NH3 PbI3 perovskite/PCBM PHJ hybrid solar cells with a respectable solar-to-electrical PCE of 7.8%. The better energy level alignment and improved wetting of the NiOx electrode interlayer significantly enhance the overall photovoltaic performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Effect of A-site deficiency in LaMn{sub 0.9}Co{sub 0.1}O{sub 3} perovskites on their catalytic performance for soot combustion

    Energy Technology Data Exchange (ETDEWEB)

    Dinamarca, Robinson [Department of Physical Chemistry, Faculty of Chemical Sciences, University of Concepción, Concepción (Chile); Garcia, Ximena; Jimenez, Romel [Department of Chemical Engineering, Faculty of Engineering, University of Concepción, Concepción (Chile); Fierro, J.L.G. [Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid (Spain); Pecchi, Gina, E-mail: gpecchi@udec.cl [Department of Physical Chemistry, Faculty of Chemical Sciences, University of Concepción, Concepción (Chile)

    2016-09-15

    Highlights: • A-site defective perovskites increases the oxidation state of the B-cation. • Not always non-stoichiometric perovskites exhibit higher catalytic activity in soot combustion. • The highly symmetric cubic crystalline structure diminishes the redox properties of perovskites. - Abstract: The influence of lanthanum stoichiometry in Ag-doped (La{sub 1-x}Ag{sub x}Mn{sub 0.9}Co{sub 0.1}O{sub 3}) and A-site deficient (La{sub 1-x}Mn{sub 0.9}Co{sub 0.1}O{sub 3-δ}) perovskites with x equal to 10, 20 and 30 at.% has been investigated in catalysts for soot combustion. The catalysts were prepared by the amorphous citrate method and characterized by XRD, nitrogen adsorption, XPS, O{sub 2}-TPD and TPR. The formation of a rhombohedral excess-oxygen perovskite for Ag-doped and a cubic perovskite structure for an A-site deficient series is confirmed. The efficient catalytic performance of the larger Ag-doped perovskite structure is attributed to the rhombohedral crystalline structure, Ag{sub 2}O segregated phases and the redox pair Mn{sup 4+}/Mn{sup 3+}. A poor catalytic activity for soot combustion was observed with A-site deficient perovskites, despite the increase in the redox pair Mn{sup 4+}/Mn{sup 3+}, which is attributed to the cubic crystalline structure.

  8. Morphology modification of perovskite film by a simple post-treatment process in perovskite solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Song, J.; Yang, Y.; Zhao, Y.L., E-mail: sdyulong@cumt.edu.cn; Che, M.; Zhu, L.; Gu, X.Q.; Qiang, Y.H., E-mail: yhqiang@cumt.edu.cn

    2017-03-15

    Highlights: • Perovskite films were post-treated by DMF/CBZ, DMSO/CBZ, or GBL/CBZ blend solvents. • This process could repair pinholes and enhance coverage in perovskite film. • This technique could modify charge transfer process at TiO{sub 2}/perovskite interface. - Abstract: A homogenous perovskite thin film with high coverage is a determining factor for high performance perovskite solar cells. Unlike previous pre-treatments aiming at perovskite precursor, we proposed a simple method to modify the morphology of perovskite films by post-treatment process using mixed solvents of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or 1,4-butyrolactone (GBL) with chlorobenzene (CBZ) in this paper. As good solvent of perovskite, DMF, DMSO, and GBL could dissolve the formed perovskite film. Meanwhile, CBZ, anti-solvent of perovskite film, could decrease the dissolving capacity of these good solvents. Therefore, the perovskite film coverage might be improved by the partial dissolution and recrystallization after solvent post-treatment process. Electrochemical impedance spectrometry (EIS) and time-resolved photoluminescence (TRPL) indicated that this post-treatment process could enhance charge transfer at TiO{sub 2}/perovskite interface. Finally, the conversion efficiency increased from 10.10% to 11.82%, 11.68%, and 10.66% using perovskite films post-treated by DMF/CBZ, DMSO/CBZ, and GBL/CBZ blend solvents, respectively.

  9. Ordered perovskites with cationic vacancies. 11. System Ba/sub 2/Gd/sub 2/3/vacant/sub 1/3/U/sub 1-x/W/sub x/O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Wischert, W; Oelkrug, D; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1982-12-01

    The cation deficient polymorphic perovskites Ba/sub 2/Gd/sub 2/3/vacant/sub 1/3/UO/sub 6/ and Ba/sub 2/Gd/sub 2/3/vacant/sub 1/3/WO/sub 6/ form a continuous series of mixed crystals, which crystallize over a wide range (x = 0.1 up to 0.99) in a cubic 1:1 ordered perovskite lattice. According to the investigations of the vibrational spectra, the diffuse reflectance spectra, and the photoluminescence - opposite to isostructural perovskites wihout vacancies - different species of UO/sub 6/ and WO/sub 6/ octahedra are present. Numerous differences in properties - e.g. an orange emission colour in comparison with a green one by absence of vacancies - are based upon that.

  10. Photo-stability of CsPbBr3 perovskite quantum dots for optoelectronic application

    NARCIS (Netherlands)

    Chen, Junsheng; Liu, Dongzhou; Al-Marri, Mohammed J.; Nuuttila, Lauri; Lehtivuori, Heli; Zheng, Kaibo

    Due to their superior photoluminescence (PL) quantum yield (QY) and tunable optical band gap, all-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted intensive attention for the application in solar cells, light emitting diodes (LED), photodetectors and laser devices. In this scenario,

  11. Hybrid Organic-Inorganic Perovskite Photodetectors.

    Science.gov (United States)

    Tian, Wei; Zhou, Huanping; Li, Liang

    2017-11-01

    Hybrid organic-inorganic perovskite materials garner enormous attention for a wide range of optoelectronic devices. Due to their attractive optical and electrical properties including high optical absorption coefficient, high carrier mobility, and long carrier diffusion length, perovskites have opened up a great opportunity for high performance photodetectors. This review aims to give a comprehensive summary of the significant results on perovskite-based photodetectors, focusing on the relationship among the perovskite structures, device configurations, and photodetecting performances. An introduction of recent progress in various perovskite structure-based photodetectors is provided. The emphasis is placed on the correlation between the perovskite structure and the device performance. Next, recent developments of bandgap-tunable perovskite and hybrid photodetectors built from perovskite heterostructures are highlighted. Then, effective approaches to enhance the stability of perovskite photodetector are presented, followed by the introduction of flexible and self-powered perovskite photodetectors. Finally, a summary of the previous results is given, and the major challenges that need to be addressed in the future are outlined. A comprehensive summary of the research status on perovskite photodetectors is hoped to push forward the development of this field. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A Direct Bandgap Copper-Antimony Halide Perovskite.

    Science.gov (United States)

    Vargas, Brenda; Ramos, Estrella; Pérez-Gutiérrez, Enrique; Alonso, Juan Carlos; Solis-Ibarra, Diego

    2017-07-12

    Since the establishment of perovskite solar cells (PSCs), there has been an intense search for alternative materials to replace lead and improve their stability toward moisture and light. As single-metal perovskite structures have yielded unsatisfactory performances, an alternative is the use of double perovskites that incorporate a combination of metals. To this day, only a handful of these compounds have been synthesized, but most of them have indirect bandgaps and/or do not have bandgaps energies well-suited for photovoltaic applications. Here we report the synthesis and characterization of a unique mixed metal ⟨111⟩-oriented layered perovskite, Cs 4 CuSb 2 Cl 12 (1), that incorporates Cu 2+ and Sb 3+ into layers that are three octahedra thick (n = 3). In addition to being made of abundant and nontoxic elements, we show that this material behaves as a semiconductor with a direct bandgap of 1.0 eV and its conductivity is 1 order of magnitude greater than that of MAPbI 3 (MA = methylammonium). Furthermore, 1 has high photo- and thermal-stability and is tolerant to humidity. We conclude that 1 is a promising material for photovoltaic applications and represents a new type of layered perovskite structure that incorporates metals in 2+ and 3+ oxidation states, thus significantly widening the possible combinations of metals to replace lead in PSCs.

  13. Self-propagating high-temperature synthesis of Sr-doped LaMnO3 perovskite as oxidation catalyst

    International Nuclear Information System (INIS)

    Hirano, T.; Purwanto, H.; Watanabe, T.; Akiyama, T.

    2007-01-01

    Sr-doped LaMnO 3 perovskite oxide has been focused on as one of the alternative catalysts to precious metals such as platinum that are used for cleaning automotive emission gas. The conventional Solid-state reaction method is a popular productive process for perovskite oxide, however, it is time and energy consuming process because it requires repeated prolonged heat treatment at high temperatures. Therefore, the purposes of this work are to produce Sr-doped LaMnO 3 perovskite by using Self-propagating high-temperature synthesis (SHS) and experimentally examine the oxidation catalytic activity of the product for cleaning automotive emission gas. In the SHS, powders of La 2 O 3 , SrCO 3 , Mn and NaClO 4 were well mixed at the desired ratio and poured in a graphite crucible, where at one end it was ignited by using an electrically heated carbon foil. The wave of exothermic reaction due to oxidation of manganese propagated to the other end in a short time. The obtained products were characterized by means of XRD, FE-SEM, BET and particle size distribution analysis and then evaluated via catalytic oxidation tests by using propane in a fixed bed reactor at several temperatures. From the XRD analysis, the products had the desired composition of La 1-x Sr x MnO 3 (x = 0, 0.1, 0.2 and 0.4) perovskite, in which the replacing ratio x of La and Sr in the products was easily controlled by changing the mixing ratio of raw materials. The catalytic activity test showed that the samples exhibited good catalytic activity for propane oxidation over 200 deg. C , although the products had a relatively small surface area. SHS showed the potential for the production of a relatively inexpensive catalytic converter

  14. Thermodynamic stability and kinetics of perovskite dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Nesbitt, H W; Bancroft, G M; Fyfe, W S; Karkhanis, S N; Nishijima, A [Western Ontario Univ., London (Canada); Shin, S [National Chemical Lab. for Industry, Tsukuba (Japan)

    1981-01-29

    Perovskite, a SYNROC host mineral for nuclear wastes, is thermodynamically unstable in natural waters and in association with common minerals. Leach experiments demonstrate that CaTiO/sub 3/ (perovskite), SrTiO/sub 3/ and BaTiO/sub 3/ are as reactive as some silicate glasses below 100/sup 0/C, but leach much more slowly than glasses above 100/sup 0/C.

  15. The influence of additives in the stoichiometry of hybrid lead halide perovskites

    Science.gov (United States)

    Burgués-Ceballos, Ignasi; Savva, Achilleas; Georgiou, Efthymios; Kapnisis, Konstantinos; Papagiorgis, Paris; Mousikou, Androniki; Itskos, Grigorios; Othonos, Andreas; Choulis, Stelios A.

    2017-11-01

    We investigate the employment of carefully selected solvent additives in the processing of a commercial perovskite precursor ink and analyze their impact on the performance of organometal trihalide perovskite (CH3NH3PbI3-xClx) photovoltaic devices. We provide evidence that the use of benzaldehyde can be used as an effective method to preserve the stoichiometry of the perovskite precursors in solution. Benzaldehyde based additive engineering shows to improve perovskite solid state film morphology and device performance of CH3NH3PbI3-xClx based solar cells.

  16. Three-dimensional oriented attachment growth of single-crystal pre-perovskite PbTiO3 hollowed fibers

    KAUST Repository

    Zhao, Ruoyu

    2017-12-11

    Hollowed single-crystal pre-perovskite PbTiO fibers (PP-PTF) were successfully synthesized via a polyvinyl alcohol (PVA) assisted hydrothermal process. The as-prepared PP-PTF were characterized to be 0.3-1 μm in diameter and tens of micrometers in length by adjusting the concentration of PVA to 0.8 g L. Microstructure characterization of the samples at different reaction times revealed that PP-PTF were formed via a three-dimensional (3D) hierarchical oriented attachment (OA) growth process. The initial growth units were determined to be single-crystal pre-perovskite PbTiO fibers with a diameter of 10-20 nm. Zeta potential measurement suggested that the main driving force of the OA process is the surface electrostatic force, which is induced by the incompletely bonded Pb and O atomic layers on the surface of the {110} plane. Moreover, molecular dynamics simulations have been employed to reveal a stable configuration of the initial pre-perovskite PbTiO growth units, agreeing well with the experimental results.

  17. Jahn-Teller distortions, cation ordering and octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Lufaso, M.W.; Woodward, P.M.

    2004-01-01

    In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the interplay between orbital ordering, octahedral tilting and cation ordering in perovskites. Both ternary AMX 3 perovskites containing an active Jahn-Teller (J-T) ion on the octahedral site and quaternary A 2 MM'X 6 perovskites containing a J-T ion on one-half of the octahedral sites have been examined. In AMX 3 perovskites, the tendency is for the occupied 3d 3x 2 -r 2 and 3d 3z 2 -r 2 orbitals to order in the ac plane, as exemplified by the crystal structures of LaMnO 3 and KCuF 3 . This arrangement maintains a favorable coordination environment for the anion sites. In AMX 3 perovskites, octahedral tilting tends to enhance the magnitude of the J-T distortions. In A 2 MM'X 6 perovskites, the tendency is for the occupied 3d 3z 2 -r 2 orbitals to align parallel to the c axis. This pattern maintains a favorable coordination environment about the symmetric M'-cation site. The orbital ordering found in rock-salt ordered A 2 MM'X 6 perovskites is compatible with octahedral rotations about the c axis (Glazer tilt system a 0 a 0 c - ) but appears to be incompatible with GdFeO 3 -type octahedral tilting (tilt system - b + a - ). (orig.)

  18. Patterning of Perovskite Single Crystals

    KAUST Repository

    Corzo, Daniel

    2017-06-12

    As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are

  19. Self-propagating high-temperature synthesis of LaMO{sub 3} perovskite-type oxide using heteronuclearcyano metal complex precursors

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Rodríguez, Daniel, E-mail: daniel.sanchez@udg.edu [GRMT, Department of Physics, University of Girona, Campus Montilivi, Edif.PII, E17071 Girona, Catalonia (Spain); Wada, Hiroki; Yamaguchi, Syuhei [Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan); Farjas, Jordi [GRMT, Department of Physics, University of Girona, Campus Montilivi, Edif.PII, E17071 Girona, Catalonia (Spain); Yahiro, Hidenori, E-mail: yahiro.hidenori.me@ehime-u.ac.jp [Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577 (Japan)

    2015-11-15

    The decomposition of La[Fe(CN){sub 6}]·5H{sub 2}O and La[Co(CN){sub 6}]·5H{sub 2}O under different atmospheres has been analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). In addition, the decomposition temperature at different sample locations was monitored for sample masses around 2 g of La[Fe(CN){sub 6}]·5H{sub 2}O and La[Co(CN){sub 6}]·5H{sub 2}O, when they were calcined for 1 h at temperatures ranging from 200 to 400 °C in a controlled gas-flow system. Results showed that, the large enough of the cyano complex precursors undergo combustion when they are decomposed under oxygen atmosphere. X-ray diffraction results revealed that perovskite-type oxides crystallize due to the overheating of the process. As a result, it has been possible to produce LaFeO{sub 3} and LaCoO{sub 3} perovskite-type oxide powders by SHS under oxygen atmosphere using La[Fe(CN){sub 6}]·5H{sub 2}O and La[Co(CN){sub 6}]·5H{sub 2}O as a precursor. The effect of the ignition temperature has been investigated. The specific surface area of the perovskite-type oxides produced via SHS using heteronuclearcyano metal complex as a precursor is significantly higher than that of other LaMO{sub 3} produced using the same technique but obtained from other type of precursors. - Highlights: • The decomposition of La[Fe(CN){sub 6}] and La[Co(CN){sub 6}] precursors was analyzed. • The combustion process proceeded under oxygen when sample was large enough. • Perovskite oxides via SHS from the cyano complex precursors were synthesized. • LaMO{sub 3} perovskite oxides via SHS was obtained with high specific surface area.

  20. Simplified Perovskite Solar Cell with 4.1% Efficiency Employing Inorganic CsPbBr3 as Light Absorber.

    Science.gov (United States)

    Duan, Jialong; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2018-04-17

    Perovskite solar cells with cost-effectiveness, high power conversion efficiency, and improved stability are promising solutions to the energy crisis and environmental pollution. However, a wide-bandgap inorganic-semiconductor electron-transporting layer such as TiO 2 can harvest ultraviolet light to photodegrade perovskite halides, and the high cost of a state-of-the-art hole-transporting layer is an economic burden for commercialization. Here, the building of a simplified cesium lead bromide (CsPbBr 3 ) perovskite solar cell with fluorine-doped tin oxide (FTO)/CsPbBr 3 /carbon architecture by a multistep solution-processed deposition technology is demonstrated, achieving an efficiency as high as 4.1% and improved stability upon interfacial modification by graphene quantum dots and CsPbBrI 2 quantum dots. This work provides new opportunities of building next-generation solar cells with significantly simplified processes and reduced production costs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Improvement of photovoltaic performance of the inverted planar perovskite solar cells by using CH3NH3PbI3-xBrx films with solvent annealing

    Science.gov (United States)

    Wang, Shan; Zhang, Weijia; Ma, Denghao; Jiang, Zhaoyi; Fan, Zhiqiang; Ma, Qiang; Xi, Yilian

    2018-01-01

    In this paper, the CH3NH3PbI3-xBrx films with various Br-doping contents were successfully prepared by solution processed deposition and followed by annealing process. This method simultaneously modified the morphology and composition of the CH3NH3PbI3 film. The effects of annealing treatment of CH3NH3PbI3-xBrx films under N2 and DMSO conditions on the microstructure of films and photoelectric properties of the solar cells were systematically investigated. The relationship of the component ratio of RBr/I= CH3NH3PbI3-xBrx/CH3NH3PbI3 in the resulting perovskite versus CH3NH3Br concentration also was explored. The results revealed that the CH3NH3PbI3-xBrx films annealed under DMSO exhibited increased grain sizes, enhanced crystallinity, enlarged bandgap and reduced defect density compared with that of the N2 annealing. It also was found that the RBr/I linearly increased in the resulting perovskite with the increased of CH3NH3Br concentration in the methylammonium halide mixture solutions. Furthermore, the photovoltaic performances of devices fabricated using DMSO precursor solvent were worse than that of DMF under N2 annealing atmosphere. When CH3NH3Br concentration was 7.5 mg ml-1, the planar perovskite solar cell based on CH3NH3PbI3-xBrx annealed under DMSO showed the best efficiency of 13.7%.

  2. The Recombination Mechanism and True Green Amplified Spontaneous Emission in CH3NH3PbBr3 Perovskite

    KAUST Repository

    Priante, Davide

    2015-08-01

    True-green wavelength emitters at 555 nm are currently dominated by III-V semiconductor-based inorganic materials. Nevertheless, due to high lattice- and thermal-mismatch, the overall power efficiency in this range tends to decline for high current density showing the so-called efficiency droop in the green region (“green gap”). In order to fill the research green gap, this thesis examines the low cost solution-processability of organometal halide perovskites, which presents a unique opportunity for light-emitting devices in the green-yellow region owing to their superior photophysic properties such as high photoluminescence quantum efficiency, small capture cross section of defect states as well as optical bandgap tunability across the visible light regime. Specifically, the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material were investigated using low-temperature, power-dependent (77 K), temperature-dependent photoluminescence (PL) measurements. We noted three recombination peaks at 77K, one of which originated from bulk defect states, and other two from surface defect states. The latter were identified as bound-excitonic (BE) radiative transitions related to particle size inhomogeneity or grain size induced surface state in the sample. Both transitions led to PL spectra broadening as a result of concurrent blue- and red-shifts of these excitonic peaks. The blue-shift is most likely due to the Burstein-Moss (band filling) effect. Interestingly, the red-shift of the second excitonic peak becomes pronounced with increasing temperature leading to a true-green wavelength of 553 nm for CH3NH3PbBr3. On the other hand, red-shifted peak originates from the strong absorption in the second excitonic peak owed to the high density of surface states and carrier filling of these states due to the excitation from the first excitonic recombination. We also achieved amplified spontaneous emission around excitation threshold energy of 350 μJ/cm2

  3. The Effect of Solvents on the Performance of CH3NH3PbI3 Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Pao-Hsun Huang

    2017-04-01

    Full Text Available The properties of perovskite solar cells (PSCs fabricated using various solvents was studied. The devices had an indium tin oxide (ITO/poly(3,4-ethylenedioxythiophene: poly(styrenesulfonate (PEDOT:PSS/CH3NH3PbI3 (fabricated by using various solvents/fullerene (C60/bathocuproine (BCP/silver (Ag structure. The solvents used were dimethylformamide (DMF, γ-butyrolactone (GBL, dimethyl sulfoxide (DMSO, a mixture of DMSO and DMF (1:1 v/v, and a mixture of DMSO and GBL (DMSO: GBL, 1:1 v/v, respectively. The power conversion efficiency (PCE of the device fabricated using DMF is zero, which is attributed to the poor coverage of CH3NH3PbI3 film on the substrate. In addition, the PCE of the device made using GBL is only 1.74% due to the low solubility of PbI2 and CH3NH3I. In contrast, the PCE of the device fabricated using the solvents containing DMSO showed better performance. This is ascribed to the high solubilization properties and strong coordination of DMSO. As a result, a PCE of 9.77% was obtained using a mixed DMSO:GBL solvent due to the smooth surface, uniform film coverage on the substrate and the high crystallization of the perovskite structure. Finally, a mixed DMSO: DMF:GBL (5:2:3 v/v/v solvent that combined the advantages of each solvent was used to fabricate a device, leading to a further improvement of the PCE of the resulting PSC to 10.84%.

  4. Partial substitution of manganese with cerium in SrMnO{sub 3} nano-perovskite catalyst. Effect of the modification on the catalytic combustion of dilute acetone

    Energy Technology Data Exchange (ETDEWEB)

    Rezlescu, Nicolae, E-mail: nicolae.rezlescu@gmail.com [National Institute of Research and Development for Technical Physics, Iasi (Romania); Rezlescu, Elena; Popa, Paul Dorin; Doroftei, Corneliu [National Institute of Research and Development for Technical Physics, Iasi (Romania); Ignat, Maria [“Al. I. Cuza” University, Faculty of Chemistry, Iasi (Romania)

    2016-10-01

    Ultrafine SrMn{sub 1−x}Ce{sub x}O{sub 3} (x = 0, 02) perovskites were prepared by self-combustion method and heat treatment at 1000 °C for 4 h. The structure and surface properties were investigated by X-ray powder diffraction, scanning electron microscopy (SEM), EDX spectroscopy, and BET analysis. The catalyst properties of the perovskite nanopowders were tested in the catalytic combustion of dilute acetone at atmospheric pressure. The results revealed that the partial substitution of Mn by Ce ions (x = 0.2) in perovskite structure of SrMnO{sub 3} had significantly improved catalytic activity of the perovskite. The SrMn{sub 0.8}Ce{sub 0,2}O{sub 3} perovskite composition can be a good candidate for catalytic combustion of low concentration acetone (1–2‰ in air) at low temperatures. The acetone conversion over this catalyst exceeds 90% at 200 °C, whereas over SrMnO{sub 3} it is only 50%. Compared with SrMnO{sub 3}, T{sub 50} is decreased by 75 °C and T{sub 90} is decreased by 70 °C. The enhancement of the catalytic activity at a Ce doping of 0.2 may be ascribed to smaller crystallite sizes, larger specific surface area and the presence of Ce and Mn cations with variable valence in the perovskite structure. - Highlights: • A non-conventional method was used to make nanostructured perovskite samples. • XRD study confirms perovskite structure and nanosize of crystallites. • EDX analyses confirm homogeneity and purity of the samples. • The catalytic testing was carried out in the flameless combustion of dilute acetone. • SrMn{sub 0.8}Ce{sub 0.2}O{sub 3} perovskite can be a promising catalyst for acetone combustion at low temperature.

  5. Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation

    Science.gov (United States)

    Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui

    2018-04-01

    The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n  >  2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n  >  2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n  =  2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.

  6. Determining the energetics of vicinal perovskite oxide surfaces

    NARCIS (Netherlands)

    Wessels, W.A.; Bollmann, Tjeerd Rogier Johannes; Koster, Gertjan; Zandvliet, Henricus J.W.; Rijnders, Augustinus J.H.M.

    2017-01-01

    The energetics of vicinal SrTiO3(001) and DyScO3(110), prototypical perovskite vicinal surfaces, has been studied using topographic atomic force microscopy imaging. The kink formation and strain relaxation energies are extracted from a statistical analysis of the step meandering. Both perovskite

  7. Effect of Annealing Process on CH3NH3PbI3-XClX Film Morphology of Planar Heterojunction Perovskite Solar Cells with Optimal Compact TiO2 Layer

    Directory of Open Access Journals (Sweden)

    Dan Chen

    2017-01-01

    Full Text Available The morphology of compact TiO2 film used as an electron-selective layer and perovskite film used as a light absorption layer in planar perovskite solar cells has a significant influence on the photovoltaic performance of the devices. In this paper, the spin coating speed of the compact TiO2 is investigated in order to get a high-quality film and the compact TiO2 film exhibits pinhole- and crack-free films treated by 2000 rpm for 60 s. Furthermore, the effect of annealing process, including annealing temperature and annealing program, on CH3NH3PbI3-XClX film morphology is studied. At the optimal annealing temperature of 100°C, the CH3NH3PbI3-XClX morphology fabricated by multistep slow annealing method has smaller grain boundaries and holes than that prepared by one-step direct annealing method, which results in the reduction of grain boundary recombination and the increase of Voc. With all optimal procedures, a planar fluorine-doped tin oxide (FTO substrate/compact TiO2/CH3NH3PbI3-XClX/Spiro-MeOTAD/Au cell is prepared for an active area of 0.1 cm2. It has achieved a power conversion efficiency (PCE of 14.64%, which is 80.3% higher than the reference cell (8.12% PCE without optimal perovskite layer. We anticipate that the annealing process with optimal compact TiO2 layer would possibly become a promising method for future industrialization of planar perovskite solar cells.

  8. Perovskite Catalysts—A Special Issue on Versatile Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Yu-Chuan Lin

    2014-08-01

    Full Text Available Perovskite-type catalysts have been prominent oxide catalysts for many years due to attributes such as flexibility in choosing cations, significant thermal stability, and the unique nature of lattice oxygen. Nearly 90% metallic elements of the Periodic Table can be stabilized in perovskite’s crystalline framework [1]. Moreover, by following the Goldschmidt rule [2], the A- and/or B-site elements can be partially substituted, making perovskites extremely flexible in catalyst design. One successful example is the commercialization of noble metal-incorporated perovskites (e.g., LaFe0.57Co0.38Pd0.05O3 for automotive emission control used by Daihatsu Motor Co. Ltd. [3]. Thus, growing interest in, and application of perovskites in the fields of material sciences, heterogeneous catalysis, and energy storage have prompted this Special Issue on perovskite catalysts. [...

  9. Revealing the properties of defects formed by CH3NH2 molecules in organic-inorganic hybrid perovskite MAPbBr3

    Science.gov (United States)

    Wang, Ji; Zhang, Ao; Yan, Jun; Li, Dan; Chen, Yunlin

    2017-03-01

    The properties of defects in organic-inorganic hybrid perovskite are widely studied from the first-principles calculation. However, the defects of methylamine (methylamine = CH3NH2), which would be easily formed during the preparation of the organic-inorganic hybrid perovskite, are rarely investigated. Thermodynamic properties as well as defect states of methylamine embedded MAPbX3 (MA = methyl-ammonium = CH3NH3, X = Br, I) are studied based on first-principles calculations of density functional theory. It was found that there is a shallow defect level near the highest occupied molecular orbital, which induced by the interstitial methylamine defect in MAPbBr3, will lead to an increase of photoluminescence. The calculation results showed that interstitial defect states of methylamine may move deeper due to the interaction between methylamine molecules and methyl-ammonium cations. It was also showed that the interstitial methylamine defect is stable at room temperature, and the defect can be removed easily by annealing.

  10. Coherent intergrowth of simple cubic and quintuple tetragonal perovskites in the system Nd_2_−_εBa_3_+_ε(Fe_,Co)_5O_1_5_−_δ

    International Nuclear Information System (INIS)

    Kundu, Asish K.; Yu Mychinko, Mikhail; Caignaert, Vincent; Lebedev, Oleg I.; Volkova, Nadezhda E.; Deryabina, Ksenia M.; Cherepanov, Vladimir A.; Raveau, Bernard

    2015-01-01

    Investigation of the Nd_2_−_εBa_3_+_ε(Fe,Co)_5O_1_5_−_δ system, combining X-ray diffraction and electron microscopy, has allowed a tetragonal quintuple ordered perovskite “a_p×a_p×5a_p” phasoid inter-grown within a single cubic perovskite matrix to be evidenced for ε=0. This nanoscale chemically twinned perovskite is compared with other members, Ln=Sm, Eu, Pr. The unusual long range ordering of the layers develops strains due to size mismatch between Ba"2"+ and Ln"3"+ cations. Importantly, two factors allow the strains to be decreased: (i) special intergrowths of double (LnBaFe_2O_6_−_δ) and triple (LnBa_2Fe_3O_9_−_δ) perovskite ribbons/layers oriented at 90°, (ii) nanoscale chemical twinning. The spin locking effect of the nano-domain boundaries upon the magnetic properties of these perovskites is discussed. - Graphical abstract: Nd_2Ba_3Fe_5O_1_4_._5_4 is a tetragonal quintuple perovskite phasoid embedded in a simple cubic perovskite matrix, which shows collinear antiferromagnetic behavior.

  11. Structural and Quantitative Investigation of Perovskite Pore Filling in Mesoporous Metal Oxides

    Directory of Open Access Journals (Sweden)

    Shany Gamliel

    2016-11-01

    Full Text Available In recent years, hybrid organic–inorganic perovskite light absorbers have attracted much attention in the field of solar cells due to their optoelectronic characteristics that enable high power conversion efficiencies. Perovskite-based solar cells’ efficiency has increased dramatically from 3.8% to more than 20% in just a few years, making them a promising low-cost alternative for photovoltaic applications. The deposition of perovskite into a mesoporous metal oxide is an influential factor affecting solar cell performance. Full coverage and pore filling into the porous metal oxide are important issues in the fabrication of highly-efficient mesoporous perovskite solar cells. In this work, we carry out a structural and quantitative investigation of CH3NH3PbI3 pore filling deposited via sequential two-step deposition into two different mesoporous metal oxides—TiO2 and Al2O3. We avoid using a hole conductor in the perovskite solar cells studied in this work to eliminate undesirable end results. Filling oxide pores with perovskite was characterized by Energy Dispersive X-ray Spectroscopy (EDS in Transmission Electron Microscopy (TEM on cross-sectional focused ion beam (FIB lamellae. Complete pore filling of CH3NH3PbI3 perovskite into the metal oxide pores was observed down to X-depth, showing the presence of Pb and I inside the pores. The observations reported in this work are particularly important for mesoporous Al2O3 perovskite solar cells, as pore filling is essential for the operation of this solar cell structure. This work presents structural and quantitative proof of complete pore filling into mesoporous perovskite-based solar cells, substantiating their high power conversion efficiency.

  12. Hybrid solar cells composed of perovskite and polymer photovoltaic structures

    Science.gov (United States)

    Phaometvarithorn, Apatsanan; Chuangchote, Surawut; Kumnorkaew, Pisist; Wootthikanokkhan, Jatuphorn

    2018-06-01

    Organic/inorganic lead halide perovskite solar cells have recently attracted much attention in photovoltaic research, due to the devices show promising ways to achieve high efficiencies. The perovskite devices with high efficiencies, however, are typically fabricated in tandem solar cell which is complicated. In this research work, we introduce a solar cell device with the combination of CH3NH3PbI3-xClx perovskite and bulk heterojunction PCDTBT:PC70BM polymer without any tandem structure. The new integrated perovskite/polymer hybrid structure of ITO/PEDOT:PSS/perovskite/PCDTBT:PC70BM/PC70BM/TiOx/Al provides higher power conversion efficiency (PCE) of devices compared with conventional perovskite cell structure. With the optimized PCDTBT:PC70BM thickness of ∼70 nm, the highest PCE of 11.67% is achieved. Variation of conducting donor polymers in this new structure is also preliminary demonstrated. This study provides an attractively innovative structure and a promising design for further development of the new-generation solar cells.

  13. Water-assisted size and shape control of CsPbBr{sub 3} perovskite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyu [State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun (China); Department of Materials Science, Key Laboratory of Mobile Materials MOE, State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun (China); Bai, Xue; Wu, Hua; Zhang, Xiangtong; Sun, Chun; Zhang, Yu [State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun (China); Zhang, Wei; Zheng, Weitao [Department of Materials Science, Key Laboratory of Mobile Materials MOE, State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun (China); Yu, William W. [State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun (China); Department of Chemistry and Physics, Louisiana State University, Shreveport, LA (United States); Rogach, Andrey L. [Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP), City University of Hong Kong, Kowloon (China)

    2018-03-19

    Lead-halide perovskites are well known to decompose rapidly when exposed to polar solvents, such as water. Contrary to this common-place observation, we have found that through introducing a suitable minor amount of water into the reaction mixture, we can synthesize stable CsPbBr{sub 3} nanocrystals. The size and the crystallinity, and as a result the band gap tunability of the strongly emitting CsPbBr{sub 3} nanocrystals correlate with the water content. Suitable amounts of water change the crystallization environment, inducing the formation of differently shaped perovskites, namely spherical NCs, rectangular nanoplatelets, or nanowires. Bright CsPbBr{sub 3} nanocrystals with the photoluminescence quantum yield reaching 90 % were employed for fabrication of inverted hybrid inorganic/organic light-emitting devices, with the peak luminance of 4428 cd m{sup -2} and external quantum yield of 1.7 %. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Excitations Partition into Two Distinct Populations in Bulk Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lili [Department of Chemistry, The James Franck Institute, The Institute for Biophysical Dynamics, The University of Chicago, Chicago IL 60637 USA; Brawand, Nicholas P. [The Institute for Molecular Engineering, The University of Chicago, Chicago IL 60637 USA; Vörös, Márton [Materials Science Division, Argonne National Laboratory, Lemont IL 60439 USA; Dahlberg, Peter D. [Department of Chemistry, The James Franck Institute, The Institute for Biophysical Dynamics, The University of Chicago, Chicago IL 60637 USA; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Otto, John P. [Department of Chemistry, The James Franck Institute, The Institute for Biophysical Dynamics, The University of Chicago, Chicago IL 60637 USA; Williams, Nicholas E. [Department of Chemistry, The James Franck Institute, The Institute for Biophysical Dynamics, The University of Chicago, Chicago IL 60637 USA; Tiede, David M. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont IL 60439 USA; Galli, Giulia [The Institute for Molecular Engineering, The University of Chicago, Chicago IL 60637 USA; Materials Science Division, Argonne National Laboratory, Lemont IL 60439 USA; Engel, Gregory S. [Department of Chemistry, The James Franck Institute, The Institute for Biophysical Dynamics, The University of Chicago, Chicago IL 60637 USA

    2018-01-09

    Organolead halide perovskites convert optical excitations to charge carriers with remarkable efficiency in optoelectronic devices. Previous research predominantly documents dynamics in perovskite thin films; however, extensive disorder in this platform may obscure the observed carrier dynamics. Here, carrier dynamics in perovskite single-domain single crystals is examined by performing transient absorption spectroscopy in a transmissive geometry. Two distinct sets of carrier populations that coexist at the same radiation fluence, but display different decay dynamics, are observed: one dominated by second-order recombination and the other by third-order recombination. Based on ab initio simulations, this observation is found to be most consistent with the hypothesis that free carriers and localized carriers coexist due to polaron formation. The calculations suggest that polarons will form in both CH3NH3PbBr3 and CH3NH3PbI3 crystals, but that they are more pronounced in CH3NH3PbBr3. Single-crystal CH3NH3PbBr3 could represent the key to understanding the impact of polarons on the transport properties of perovskite optoelectronic devices.

  15. PbCl2-tuned inorganic cubic CsPbBr3(Cl) perovskite solar cells with enhanced electron lifetime, diffusion length and photovoltaic performance

    Science.gov (United States)

    Li, Bo; Zhang, Yanan; Zhang, Luyuan; Yin, Longwei

    2017-08-01

    Inorganic CsPbBr3 perovskite is arousing great interest following after organic-inorganic hybrid halide perovskites, and is found as a good candidate for photovoltaic devices for its prominent photoelectric property and stability. Herein, we for the first time report on PbCl2-tuned inorganic Cl-doped CsPbBr3(Cl) perovskite solar cells with adjustable crystal structure and Cl doping for enhanced carrier lifetime, extraction rate and photovoltaic performance. The effect of PbCl2 on the morphologies, structures, optical, and photovoltaic performance of CsPbBr3 perovskite solar cells is investigated systemically. Compared with orthorhombic CsPbBr3, cubic CsPbBr3 demonstrates a significant improvement for electron lifetime (from 6.7 ns to 12.3 ns) and diffusion length (from 69 nm to 197 nm), as well as the enhanced electron extraction rate from CsPbBr3 to TiO2. More importantly, Cl doping benefits the further enhancement of carrier lifetime (14.3 ns) and diffusion length (208 nm). The Cl doped cubic CsPbBr3(Cl) perovskite solar cell exhibits a Jsc of 8.47 mA cm-2 and a PCE of 6.21%, superior to that of pure orthorhombic CsPbBr3 (6.22 mA cm-2 and 3.78%). The improvement of photovoltaic performance can be attributed to enhanced carrier lifetime, diffusion length and extraction rates, as well as suppressed nonradiative recombination.

  16. The influence of additives in the stoichiometry of hybrid lead halide perovskites

    Directory of Open Access Journals (Sweden)

    Ignasi Burgués-Ceballos

    2017-11-01

    Full Text Available We investigate the employment of carefully selected solvent additives in the processing of a commercial perovskite precursor ink and analyze their impact on the performance of organometal trihalide perovskite (CH3NH3PbI3−xClx photovoltaic devices. We provide evidence that the use of benzaldehyde can be used as an effective method to preserve the stoichiometry of the perovskite precursors in solution. Benzaldehyde based additive engineering shows to improve perovskite solid state film morphology and device performance of CH3NH3PbI3−xClx based solar cells.

  17. General Strategy for Rapid Production of Low-Dimensional All-Inorganic CsPbBr3 Perovskite Nanocrystals with Controlled Dimensionalities and Sizes.

    Science.gov (United States)

    Liu, Wenna; Zheng, Jinju; Cao, Sheng; Wang, Lin; Gao, Fengmei; Chou, Kuo-Chih; Hou, Xinmei; Yang, Weiyou

    2018-02-05

    Currently, all-inorganic CsPbX 3 (X = Br, I, Cl) perovskite nanocrystals (NCs) are shining stars with exciting potential applications in optoelectronic devices such as solar cells, light-emitting diodes, lasers, and photodetectors, due to their superior performance in comparison to their organic-inorganic hybrid counterparts. In the present work, we report a general strategy based on a microwave technique for the rapid production of low-dimensional all-inorganic CsPbBr 3 perovskite NCs with tunable morphologies within minutes. The effect of the key parameters such as the introduced ligands, solvents, and PbBr 2 precursors and microwave powers as well as the irradiation times on the production of perovskite NCs was systematically investigated, which allowed their growth with tunable dimensionalities and sizes. As a proof of concept, the ratio of OA to OAm as well as the concentration of PbBr 2 precursor played important roles in triggering the anisotropic growth of the perovskite NCs, favoring their growth into 1D/2D single-crystalline nanostructures. Meanwhile, their sizes could be tailored by controlling the microwave powers and irradiation times. The mechanism for the tunable growth of perovskite NCs is discussed.

  18. Mechanical properties of hybrid organic-inorganic CH3NH3BX3 (B = Sn, Pb; X = Br, I perovskites for solar cell absorbers

    Directory of Open Access Journals (Sweden)

    Jing Feng

    2014-08-01

    Full Text Available The crystal structures, elastic and anisotropic properties of CH3NH3BX3 (B = Sn, Pb; X = Br, I compounds as solar cell absorber layers are investigated by the first-principles calculations. The type and strength of chemical bond B-X are found to determine the elastic properties. B-X bonds and the organic cations are therefore crucial to the functionalities of such absorbers. The bulk, shear, Young's modulus ranges from 12 to 30 GPa, 3 to 12 GPa, and 15 to 37 GPa, respectively. Moreover, the interaction among organic and inorganic ions would have negligible effect for elastic properties. The B/G and Poisson's ratio show it would have a good ductile ability for extensive deformation as a flexible/stretchable layer on the polymer substrate. The main reason is attributed to the low shear modulus of such perovskites. The anisotropic indices AU, AB AG, A1, A2, and A3 show ABX3 perovskite have very strong anisotropy derived from the elastic constants, chemical bonds, and symmetry.

  19. Influence of the number of layers on ultrathin CsSnI3 perovskite: from electronic structure to carrier mobility

    Science.gov (United States)

    Liu, Biao; Long, Mengqiu; Cai, Meng-Qiu; Yang, Junliang

    2018-03-01

    Inorganic halide perovskites have attracted great attention in recent years as promising materials for optoelectronic devices, with ultrathin inorganic halide perovskites showing excellent properties and great potential applications. Herein, the intrinsic electronic and optical properties of ultrathin cesium tin tri-iodide (CsSnI3) perovskite with a varying number of layers are explored using first-principles calculations. The results reveal that ultrathin CsSnI3 is a direct band gap semiconductor, and the band gap continues to increase to 1.83 eV from 1.28 eV as the number of layers is reduced to one layer from the bulk. By decreasing the number of layers, the effective mass of ultrathin CsSnI3 increases, and the optical absorption intensity along the x and y directions shows that the linear dichroism becomes stronger and stronger. Furthermore, the carrier mobilities (µ) can be predicted, and they show obvious in-plane anisotropy. The µ of the electrons is higher than that of the holes, and the electron mobility along the y direction is higher than that along the x direction. The layer thickness does not distinctly influence the µ. The difference in the atomic orbital distribution has the nature of obvious anisotropy in ultrathin CsSnI3. This work suggests that ultrathin inorganic perovskite could be a potential candidate for future nano-optoelectronic devices.

  20. Control of Emission Color of High Quantum Yield CH3NH3PbBr3 Perovskite Quantum Dots by Precipitation Temperature.

    Science.gov (United States)

    Huang, He; Susha, Andrei S; Kershaw, Stephen V; Hung, Tak Fu; Rogach, Andrey L

    2015-09-01

    Emission color controlled, high quantum yield CH 3 NH 3 PbBr 3 perovskite quantum dots are obtained by changing the temperature of a bad solvent during synthesis. The products for temperatures between 0 and 60 °C have good spectral purity with narrow emission line widths of 28-36 nm, high absolute emission quantum yields of 74% to 93%, and short radiative lifetimes of 13-27 ns.

  1. Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

    Science.gov (United States)

    Lee, Jonathan A.

    2009-01-01

    In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

  2. RF magnetron sputtered La3+-modified PZT thin films: Perovskite phase stabilization and properties

    International Nuclear Information System (INIS)

    Singh, Ravindra; Goel, T.C.; Chandra, Sudhir

    2008-01-01

    In this work, we report the preparation of lanthanum-modified lead zirconate titanate (PLZT) thin films in pure perovskite phase by RF magnetron sputtering. Various deposition parameters such as target-to-substrate spacing, sputtering gas composition, deposition temperature, post-deposition annealing temperature and time have been optimized to obtain PLZT films in pure perovskite phase. The films prepared in pure argon at 100 W RF power without external substrate heating exhibit pure perovskite phase after rapid thermal annealing (RTA) at 700 deg. C for 5 min. The film prepared at 225 deg. C substrate temperature also exhibits pure perovskite phase after RTA at 700 deg. C for 2 min. SIMS depth profile performed on one of the pure perovskite films (RTA at 700 deg. C for 5 min) shows very good stoichiometric uniformity of all elements of PLZT. The surface morphology of the films was examined using SEM and AFM. The dielectric, ferroelectric and electrical properties of the pure perovskite films were also investigated in detail. The remanent polarization for the films annealed at 700 deg. C for 5 and 2 min were found to be 15 and 13.5 μC cm -2 , respectively. Both the films have high DC resistivity of the order of 10 11 Ω cm at the electric field of ∼80 kV cm -1

  3. Resonant halide perovskite nanoparticles

    Science.gov (United States)

    Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

    2017-09-01

    The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

  4. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.; Hoogland, Sjoerd; Adachi, Michael M.; Kanjanaboos, Pongsakorn; Wong, Chris T. O.; McDowell, Jeffrey J.; Xu, Jixian; Voznyy, Oleksandr; Ning, Zhijun; Houtepen, Arjan J.; Sargent, Edward H.

    2014-01-01

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  5. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.

    2014-10-30

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  6. Determination of stoichiometry and concentration of trace elements in thin BaxSr1-xTiO3 perovskite layers.

    Science.gov (United States)

    Becker, J S; Boulyga, S F

    2001-07-01

    This paper describes an analytical procedure for determining the stoichiometry of BaxSr1-xTiO3 perovskite layers using inductively coupled plasma mass spectrometry (ICP-MS). The analytical results of mass spectrometry measurements are compared to those of X-ray fluorescence analysis (XRF). The performance and the limits of solid-state mass spectrometry analytical methods for the surface analysis of thin BaxSr1-xTiO3 perovskite layers sputtered neutral mass spectrometry (SNMS)--are investigated and discussed.

  7. An experimental and theoretical investigation of phonons and lattice instabilities in metastable decompressed SrGeO sub 3 perovskite

    CERN Document Server

    Grzechnik, A; Wolf, G H; McMillan, P F

    1998-01-01

    We report detailed Raman and IR spectroscopic measurements for the decompressed high-pressure perovskite phase of SrGeO sub 3. The appearance of a first-order Raman spectrum and slight splittings in the infrared bands suggest that the symmetry of the recovered metastable perovskite phase is lowered from Pm3m. This interpretation is fully supported by first-principles LDA calculations using the LAPW method, which indicate a small tetragonal distortion. The static lattice energy is lowered by 3.3 meV (per formula unit) by allowing rotational relaxation of the GeO sub 6 octahedra. The calculations permit a reliable assignment of the zone centre phonon modes of SrGeO sub 3 perovskite. The calculated pressure dependence of the ferroic IR-active modes is in excellent agreement with our measured data and reveals an incipient soft-mode behaviour in the tension regime. Further calculations of the GeO sub 6 unit as a function of octahedral volume reveal instabilities to local off-centre Ge sup 4 sup + displacements as ...

  8. Effect of Thermal and Structural Disorder on the Electronic Structure of Hybrid Perovskite Semiconductor CH3NH3PbI3.

    Science.gov (United States)

    Singh, Shivam; Li, Cheng; Panzer, Fabian; Narasimhan, K L; Graeser, Anna; Gujar, Tanaji P; Köhler, Anna; Thelakkat, Mukundan; Huettner, Sven; Kabra, Dinesh

    2016-08-04

    In this Letter, we investigate the temperature dependence of the optical properties of methylammonium lead iodide (MAPbI3 = CH3NH3PbI3) from room temperature to 6 K. In both the tetragonal (T > 163 K) and the orthorhombic (T photoluminescence (PL) measurements) decreases with decrease in temperature, in contrast to what is normally seen for many inorganic semiconductors, such as Si, GaAs, GaN, etc. We show that in the perovskites reported here, the temperature coefficient of thermal expansion is large and accounts for the positive temperature coefficient of the band gap. A detailed analysis of the exciton line width allows us to distinguish between static and dynamic disorder. The low-energy tail of the exciton absorption is reminiscent of Urbach absorption. The Urbach energy is a measure of the disorder, which is modeled using thermal and static disorder for both the phases separately. The static disorder component, manifested in the exciton line width at low temperature, is small. Above 60 K, thermal disorder increases the line width. Both these features are a measure of the high crystal quality and low disorder of the perovskite films even though they are produced from solution.

  9. All-perovskite transparent high mobility field effect using epitaxial BaSnO{sub 3} and LaInO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Useong; Park, Chulkwon; Kim, Young Mo; Ju, Chanjong; Park, Jisung; Char, Kookrin, E-mail: kchar@phya.snu.ac.kr [Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Ha, Taewoo; Kim, Jae Hoon [Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Namwook; Yu, Jaejun [Center for Theoretical Physics, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-03-01

    We demonstrate an all-perovskite transparent heterojunction field effect transistor made of two lattice-matched perovskite oxides: BaSnO{sub 3} and LaInO{sub 3}. We have developed epitaxial LaInO{sub 3} as the gate oxide on top of BaSnO{sub 3}, which were recently reported to possess high thermal stability and electron mobility when doped with La. We measured the dielectric properties of the epitaxial LaInO{sub 3} films, such as the band gap, dielectric constant, and the dielectric breakdown field. Using the LaInO{sub 3} as a gate dielectric and the La-doped BaSnO{sub 3} as a channel layer, we fabricated field effect device structure. The field effect mobility of such device was higher than 90 cm{sup 2} V{sup −1} s{sup −1}, the on/off ratio was larger than 10{sup 7}, and the subthreshold swing was 0.65 V dec{sup −1}. We discuss the possible origins for such device performance and the future directions for further improvement.

  10. High-Pressure Single-Crystal Structures of 3D Lead-Halide Hybrid Perovskites and Pressure Effects on their Electronic and Optical Properties.

    Science.gov (United States)

    Jaffe, Adam; Lin, Yu; Beavers, Christine M; Voss, Johannes; Mao, Wendy L; Karunadasa, Hemamala I

    2016-04-27

    We report the first high-pressure single-crystal structures of hybrid perovskites. The crystalline semiconductors (MA)PbX3 (MA = CH3NH3 (+), X = Br(-) or I(-)) afford us the rare opportunity of understanding how compression modulates their structures and thereby their optoelectronic properties. Using atomic coordinates obtained from high-pressure single-crystal X-ray diffraction we track the perovskites' precise structural evolution upon compression. These structural changes correlate well with pressure-dependent single-crystal photoluminescence (PL) spectra and high-pressure bandgaps derived from density functional theory. We further observe dramatic piezochromism where the solids become lighter in color and then transition to opaque black with compression. Indeed, electronic conductivity measurements of (MA)PbI3 obtained within a diamond-anvil cell show that the material's resistivity decreases by 3 orders of magnitude between 0 and 51 GPa. The activation energy for conduction at 51 GPa is only 13.2(3) meV, suggesting that the perovskite is approaching a metallic state. Furthermore, the pressure response of mixed-halide perovskites shows new luminescent states that emerge at elevated pressures. We recently reported that the perovskites (MA)Pb(Br x I1-x )3 (0.2 < x < 1) reversibly form light-induced trap states, which pin their PL to a low energy. This may explain the low voltages obtained from solar cells employing these absorbers. Our high-pressure PL data indicate that compression can mitigate this PL redshift and may afford higher steady-state voltages from these absorbers. These studies show that pressure can significantly alter the transport and thermodynamic properties of these technologically important semiconductors.

  11. High-pressure crystal structure of elastically isotropic CaTiO3 perovskite under hydrostatic and non-hydrostatic conditions.

    Science.gov (United States)

    Zhao, Jing; Ross, Nancy L; Wang, Di; Angel, Ross J

    2011-11-16

    The structural evolution of orthorhombic CaTiO3 perovskite has been studied using high-pressure single-crystal x-ray diffraction under hydrostatic conditions up to 8.1 GPa and under a non-hydrostatic stress field formed in a diamond anvil cell (DAC) up to 4.7 GPa. Under hydrostatic conditions, the TiO6 octahedra become more tilted and distorted with increasing pressure, similar to other 2:4 perovskites. Under non-hydrostatic conditions, the experiments do not show any apparent difference in the internal structural variation from hydrostatic conditions and no additional tilts and distortions in the TiO6 octahedra are observed, even though the lattice itself becomes distorted due to the non-hydrostatic stress. The similarity between the hydrostatic and non-hydrostatic cases can be ascribed to the fact that CaTiO3 perovskite is nearly elastically isotropic and, as a consequence, its deviatoric unit-cell volume strain produced by the non-hydrostatic stress is very small; in other words, the additional octahedral tilts relevant to the extra unit-cell volume associated with the deviatoric unit-cell volume strain may be totally neglected. This study further addresses the role that three factors--the elastic properties, the crystal orientation and the pressure medium--have on the structural evolution of an orthorhombic perovskite loaded in a DAC under non-hydrostatic conditions. The influence of these factors can be clearly visualized by plotting the three-dimensional distribution of the deviatoric unit-cell volume strain in relation to the cylindrical axis of the DAC and indicates that, if the elasticity of a perovskite is nearly isotropic as it is for CaTiO3, the other two factors become relatively insignificant.

  12. High-pressure crystal structure of elastically isotropic CaTiO3 perovskite under hydrostatic and non-hydrostatic conditions

    International Nuclear Information System (INIS)

    Zhao Jing; Ross, Nancy L; Wang, Di; Angel, Ross J

    2011-01-01

    The structural evolution of orthorhombic CaTiO 3 perovskite has been studied using high-pressure single-crystal x-ray diffraction under hydrostatic conditions up to 8.1 GPa and under a non-hydrostatic stress field formed in a diamond anvil cell (DAC) up to 4.7 GPa. Under hydrostatic conditions, the TiO 6 octahedra become more tilted and distorted with increasing pressure, similar to other 2:4 perovskites. Under non-hydrostatic conditions, the experiments do not show any apparent difference in the internal structural variation from hydrostatic conditions and no additional tilts and distortions in the TiO 6 octahedra are observed, even though the lattice itself becomes distorted due to the non-hydrostatic stress. The similarity between the hydrostatic and non-hydrostatic cases can be ascribed to the fact that CaTiO 3 perovskite is nearly elastically isotropic and, as a consequence, its deviatoric unit-cell volume strain produced by the non-hydrostatic stress is very small; in other words, the additional octahedral tilts relevant to the extra unit-cell volume associated with the deviatoric unit-cell volume strain may be totally neglected. This study further addresses the role that three factors-the elastic properties, the crystal orientation and the pressure medium-have on the structural evolution of an orthorhombic perovskite loaded in a DAC under non-hydrostatic conditions. The influence of these factors can be clearly visualized by plotting the three-dimensional distribution of the deviatoric unit-cell volume strain in relation to the cylindrical axis of the DAC and indicates that, if the elasticity of a perovskite is nearly isotropic as it is for CaTiO 3 , the other two factors become relatively insignificant. (paper)

  13. Oxygen perovskites of type Ba/sub 3/Bsup(III)RuIrO/sub 9/

    Energy Technology Data Exchange (ETDEWEB)

    Duerrschmidt, E; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-11-01

    The black perovskites Ba/sub 3/Bsup(III)RuIrO/sub 9/ with Bsup(III) = La, Nd, Sm, Gd, Dy, Er, Yb, In, Sc are isotypic. They crystallize in a hexagonal BaTiO/sub 3/ structure (sequence (hcc)/sub 2/). The mean oxydation state of the noble metal ions is +4.5.

  14. Comparison of different advanced oxidation processes (AOPs) in the presence of perovskites

    International Nuclear Information System (INIS)

    Rivas, F.J.; Carbajo, M.; Beltran, F.; Gimeno, O.; Frades, J.

    2008-01-01

    The efficacy of the oxidation systems: O 3 , UV radiation, O 3 /UV radiation, O 3 /perovskite, UV radiation/perovskite, O 3 /UV radiation/perovskite, H 2 O 2 /UV radiation, H 2 O 2 /UV radiation/perovskite, has been investigated by using pyruvic acid as probe compound. Under the operating conditions used, the combination of UV radiation and hydrogen peroxide (with or without perovskites) leads to the fastest pyruvic acid removal while the best results in terms of mineralization degree are obtained when combining O 3 /UV radiation/perovskite. The effect of the variables: inlet ozone (15-75 mg L -1 ) and initial pyruvic acid (10 -3 to 10 -2 M) concentrations, catalyst load (0.01-1.5 g L -1 ) and pH (2-9) was investigated for the photocatalytic ozonation. The most influencing parameter was the ozone concentration fed to the photoreactor. A zero order was observed for pyruvic acid concentration and close to zero for catalyst load. Some deactivation is observed after reusing the catalyst, likely due to leaching of the active phase

  15. Interplay of Cation Ordering and Ferroelectricity in Perovskite Tin Iodides: Designing a Polar Halide Perovskite for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Gaoyang; Young, Joshua; Liu, Xian; Rondinelli, James M.

    2016-09-28

    Owing to its ideal semiconducting band gap and good carrier transport properties, the fully inorganic perovskite CsSnI3 has been proposed as a visible-light absorber for photovoltaic (PV) applications. However, compared to the organic inorganic lead halide perovskite CH3NH3PbI3, CsSnI3 solar cells display very low energy conversion efficiency. In this work, we propose a potential route to improve the PV properties of CsSnI3. Using first-principles calculations, we examine the crystal structures and electronic properties of CsSnI3, including its structural polymorphs. Next, we purposefully order Cs and Rb cations on the A site to create the double perovskite (CsRb)Sn2I6. We find that a stable ferroelectric polarization arises from the nontrivial coupling between polar displacements and octahedral rotations of the SnI6 network. These ferroelectric double perovskites are predicted to have energy band gaps and carrier effective masses similar to those of CsSnI3. More importantly, unlike nonpolar CsSnI3, the electric polarization present in ferroelectric (CsRb)Sn2I6 can effectively separate the photoexcited carriers, leading to novel ferroelectric PV materials with,potentially enhanced energy conversion efficiency.

  16. Application of dopant-free hole transport materials for perovskite solar cells

    International Nuclear Information System (INIS)

    Franckevincius, M.; Gulbinas, V.; Gratzel, M.; Zakeeruddin, S.; Pauerle, P.; Mishra, A.; Steck, C.

    2015-01-01

    In this work we present the synthesis, characterization and application of a series of additive and dopant free hole transport materials (HTM) for solid-state perovskite-based solar cells. Newly synthesized HTMs showed strong absorption in the visible spectral range and suitable HOMO-LUMO energy levels for the application for methylammonium lead(II) iodide (CH_3NH_3PbI_3) perovskite. Dopant-free perovskite solar cells have been fabricated using CH_3NH_3PbI_3 perovskite and the newly synthesized HTMs following sequential deposition method, which allows us to reach power conversion efficiencies as high as 11.4 %. The easy of synthesis, low cost and relatively high performance of newly synthesized HTMs has great prospects for commercial applications in the near-future. (authors)

  17. Single Vs Mixed Organic Cation for Low Temperature Processed Perovskite Solar Cells

    International Nuclear Information System (INIS)

    Mahmud, Md Arafat; Elumalai, Naveen Kumar; Upama, Mushfika Baishakhi; Wang, Dian; Wright, Matthew; Chan, Kah Howe; Xu, Cheng; Haque, Faiazul; Uddin, Ashraf

    2016-01-01

    Highlights: • Low temperature processed ZnO based single & mixed organic cation perovskite device. • 37% higher PCE in mixed cation perovskite solar cells (PSCs) than single cation ones. • Mixed cation PSCs exhibit significantly reduced photocurrent hysteresis. • Mixed cation PSCs demonstrate three fold higher device stability than single cation PSCs. • Electronic properties are analyzed using Electrochemical Impedance Spectroscopy. - Abstract: The present work reports a comparative study between single and mixed organic cation based MAPbI 3 and MA 0.6 FA 0.4 PbI 3 perovskite devices fabricated in conjunction with low temperature processed (<150 °C) ZnO electron transport layers. MA 0.6 FA 0.4 PbI 3 perovskite devices demonstrate 37% higher power conversion efficiency compared to MAPbI 3 perovskite devices developed on the ZnO ETL. In addition, MA 0.6 FA 0.4 PbI 3 devices exhibit very low photocurrent hysteresis and they are three-fold more stable than conventional MAPbI 3 PSCs (perovskite solar cells). An in-depth analysis on the charge transport properties in both fresh and aged devices has been carried out using electrochemical impedance spectroscopy analysis to comprehend the enhanced device stability of the mixed perovskite devices developed on the ZnO ETL. The study also investigates into the interfacial charge transfer characteristics associated with the ZnO/mixed organic cation perovskite interface and concomitant influence on the inherent electronic properties.

  18. Luminescence behaviour of room temperature chemical processed all-inorganic CsPbCl3 perovskite cubes

    Science.gov (United States)

    Paul, T.; Chatterjee, B. K.; Maiti, S.; Besra, N.; Thakur, S.; Sarkar, S.; Chanda, K.; Das, A.; Sarkar, P. K.; Sardar, K.; Chattopadhyay, K. K.

    2018-05-01

    All inorganic perovskites with different halide constituent have recently truncated the eyes of researchers owing to their intriguing optoelectronic features and thereby their usage perspective in photovoltaic applications, light emitting didoes and lasing devices. Here, adopting a simple, environment benign ambient conditioned chemical synthesis approach we have realized high quality cesium lead halide perovskite (CsPbCl3) cube. The crystallinity and morphological characterizations were performed by X-ray diffraction and field emission scanning electron microscope measurements respectively while the chemical composition were examined via energy-dispersive X-ray spectroscopic measurement. The as synthesized cubes crystallized in cubic phase and exhibited intense photoluminescence emission at ˜418 nm with a small FWHM value and prolonged photoluminescence decay time˜41 ns. Besides photoluminescence, these cubes displayed strong cathodoluminescence also. Accelerating voltage dependent cathodoluminescence study showed discernable differences in luminescence behaviour. We expect this synthetic strategy to be promising as it can be easily scaled up to produce bulk quantity nanoforms of different inorganic perovskites in subtle manner for the realization of several types of nanoscale devices.

  19. Stimulation of [3H]ouabain binding to rat synaptosomal (Na+ + K+)-ATPase by aluminum

    International Nuclear Information System (INIS)

    Caspers, M.L.; Dow, M.J.; Kwaiser, T.M.

    1991-01-01

    The objective of this study was to investigate the effect of aluminum on the (Na + + K + )-ATPase. Synaptosomes were prepared from the cerebral cortices of adult, male Sprague-Dawley rats. The stimulation of [ 3 H]ouabain binding to the high affinity isoform of the (Na + + K + )-ATPase produced by AlCl 3 developed slowly, with a maximum effect observed after a 40 min preincubation. AlCl 3 produced a 26.5% stimulation in [ 3 H]ouabain binding to the synaptosomal (Na + + K + )-ATPase and this stimulation increased to 33.3% at 100 μM. Scatchard analysis of [ 3 H]ouabain binding data in the presence of 100 μM AlCl 3 yielded a B max of 79.4 ± 3.5 pmol/mg protein, significantly elevated from the B max value obtained in the absence of aluminum. The K D values were similar in the presence or absence of aluminum. In summary, aluminum affects the functioning of the synaptosomal (Na + + K + )-ATPase. This may contribute, at least in part, to the disruption of neuronal function associated with disorders where elevated aluminum content in the CNS is noted

  20. Crystal structure and phase transitions in perovskite-like C(NH2)3SnCl3

    International Nuclear Information System (INIS)

    Szafranski, Marek; Stahl, Kenny

    2007-01-01

    X-ray single-crystal diffraction, high-temperature powder diffraction and differential thermal analysis at ambient and high pressure have been employed to study the crystal structure and phase transitions of guanidinium trichlorostannate, C(NH 2 ) 3 SnCl 3 . At 295 K the crystal structure is orthorhombic, space group Pbca, Z=8, a=7.7506(2) A, b=12.0958(4) A and c=17.8049(6) A, solved from single-crystal data. It is perovskite-like with distorted corner-linked SnCl 6 octahedra and with ordered guanidinium cations in the distorted cuboctahedral voids. At 400 K the structure shows a first-order order-disorder phase transition. The space group is changed to Pnma with Z=4, a=12.1552(2) A, b=8.8590(2) A and c=8.0175(1) A, solved from powder diffraction data and showing disordering of the guanidinium cations. At 419 K, the structure shows yet another first-order order-disorder transformation with disordering of the SnCl 3 - part. The space group symmetry is maintained as Pnma, with a=12.1786(2) A, b=8.8642(2) A and c=8.0821(2) A. The thermodynamic parameters of these transitions and the p-T phase diagram have been determined and described. - Graphical abstract: The perovskite-like crystals of C(NH 2 ) 3 SnCl 3 undergo two successive first-order phase transitions at 400 and 419 K, both accompanied by an essential order-disorder contribution. The p-T phase diagram exhibits a singular point at 219 MPa and 443 K

  1. Surface passivation of mixed-halide perovskite CsPb(BrxI1-x)3 nanocrystals by selective etching for improved stability.

    Science.gov (United States)

    Jing, Qiang; Zhang, Mian; Huang, Xiang; Ren, Xiaoming; Wang, Peng; Lu, Zhenda

    2017-06-08

    In recent years, there has been an unprecedented rise in the research of halide perovskites because of their important optoelectronic applications, including photovoltaic cells, light-emitting diodes, photodetectors and lasers. The most pressing question concerns the stability of these materials. Here faster degradation and PL quenching are observed at higher iodine content for mixed-halide perovskite CsPb(Br x I 1-x ) 3 nanocrystals, and a simple yet effective method is reported to significantly enhance their stability. After selective etching with acetone, surface iodine is partially etched away to form a bromine-rich surface passivation layer on mixed-halide perovskite nanocrystals. This passivation layer remarkably stabilizes the nanocrystals, making their PL intensity improved by almost three orders of magnitude. It is expected that a similar passivation layer can also be applied to various other kinds of perovskite materials with poor stability issues.

  2. Intrinsic point defects in inorganic perovskite CsPbI3 from first-principles prediction

    KAUST Repository

    Li, Yifan

    2017-10-19

    Cubic inorganic perovskite CsPbI3 is a direct bandgap semiconductor, which is promising for optoelectronic applications, such as solar cells, light emitting diodes, and lasers. The intrinsic defects in semiconductors play crucial roles in determining carrier conductivity, the efficiency of carrier recombination, and so on. However, the thermodynamic stability and intrinsic defect physics are still unclear for cubic CsPbI3. By using the first-principles calculations, we study the thermodynamic process and find out that the window for CsPbI3 growth is quite narrow and the concentration of Cs is important for cubic CsPbI3 growth. Under Pb-rich conditions, VPb and VI can pin the Fermi energy in the middle of the bandgap, which results in a low carrier concentration. Under Pb-poor conditions, VPb is the dominant defect and the material has a high concentration of hole carriers with a long lifetime. Our present work gives an insight view of the defect physics of cubic CsPbI3 and will be beneficial for optoelectronic applications based on cubic CsPbI3 and other analogous inorganic perovskites.

  3. Intrinsic point defects in inorganic perovskite CsPbI3 from first-principles prediction

    KAUST Repository

    Li, Yifan; Zhang, Chenhui; Zhang, Xixiang; Huang, Dan; Shen, Qian; Cheng, Yingchun; Huang, Wei

    2017-01-01

    Cubic inorganic perovskite CsPbI3 is a direct bandgap semiconductor, which is promising for optoelectronic applications, such as solar cells, light emitting diodes, and lasers. The intrinsic defects in semiconductors play crucial roles in determining carrier conductivity, the efficiency of carrier recombination, and so on. However, the thermodynamic stability and intrinsic defect physics are still unclear for cubic CsPbI3. By using the first-principles calculations, we study the thermodynamic process and find out that the window for CsPbI3 growth is quite narrow and the concentration of Cs is important for cubic CsPbI3 growth. Under Pb-rich conditions, VPb and VI can pin the Fermi energy in the middle of the bandgap, which results in a low carrier concentration. Under Pb-poor conditions, VPb is the dominant defect and the material has a high concentration of hole carriers with a long lifetime. Our present work gives an insight view of the defect physics of cubic CsPbI3 and will be beneficial for optoelectronic applications based on cubic CsPbI3 and other analogous inorganic perovskites.

  4. Bandgap calculations and trends of organometal halide perovskites

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; García Lastra, Juan Maria; Thygesen, Kristian Sommer

    2014-01-01

    Energy production from the Sun requires a stable efficient light absorber. Promising candidates in this respect are organometal perovskites (ABX3), which have been intensely investigated during the last years. Here, we have performed electronic structure calculations of 240 perovskites composed...

  5. Modulation of Charge Recombination in CsPbBr3 Perovskite Films with Electrochemical Bias

    KAUST Repository

    Scheidt, Rebecca A; Samu, Gergely F.; Janá ky, Csaba; Kamat, Prashant V.

    2017-01-01

    The charging of mesoscopic TiO2 layer in a metal halide perovskite solar cell can influence the overall power conversion efficiency. By employing CsPbBr3 films deposited on a mesoscopic TiO2 film, we have succeeded in probing the influence

  6. Charge carrier transport mechanisms in perovskite CdTiO3 fibers

    Directory of Open Access Journals (Sweden)

    Z. Imran

    2014-06-01

    Full Text Available Electrical transport properties of electrospun cadmium titanate (CdTiO3 fibers have been investigated using ac and dc measurements. Air annealing of as spun fibers at 1000 °C yielded the single phase perovskite fibers having diameter ∼600 nm - 800 nm. Both the ac and dc electrical measurements were carried out at temperatures from 200 K – 420 K. The complex impedance plane plots revealed a single semicircular arc which indicates the interfacial effect due to grain boundaries of fibers. The dielectric properties obey the Maxwell-Wagner theory of interfacial polarization. In dc transport study at low voltages, data show Ohmic like behavior followed by space charge limited current (SCLC with traps at higher voltages at all temperatures (200 K – 420 K. Trap density in our fibers system is Nt = 6.27 × 1017 /cm3. Conduction mechanism in the sample is governed by 3-D variable range hopping (VRH from 200 K – 300 K. The localized density of states were found to be N(EF = 5.51 × 1021 eV−1 cm−3 at 2 V. Other VRH parameters such as hopping distance (Rhop and hopping energy (Whop were also calculated. In the high temperature range of 320 K – 420 K, conductivity follows the Arrhenius law. The activation energy found at 2 V is 0.10 eV. Temperature dependent and higher values of dielectric constant make the perovskite CdTiO3 fibers efficient material for capacitive energy storage devices.

  7. Perovskite type nanopowders and thin films obtained by chemical methods

    Directory of Open Access Journals (Sweden)

    Viktor Fruth

    2010-09-01

    Full Text Available The review presents the contribution of the authors, to the preparation of two types of perovskites, namely BiFeO3 and LaCoO3, by innovative methods. The studied perovskites were obtained as powders, films and sintered bodies. Their complex structural and morphological characterization is also presented. The obtained results have underlined the important influence of the method of preparation on the properties of the synthesized perovskites.

  8. Alloy-Controlled Work Function for Enhanced Charge Extraction in All-Inorganic CsPbBr3 Perovskite Solar Cells.

    Science.gov (United States)

    Ding, Jie; Zhao, Yuanyuan; Duan, Jialong; He, Benlin; Tang, Qunwei

    2018-03-25

    All-inorganic CsPbX 3 (X=I, Br) perovskite solar cells are regarded as cost-effective and stable alternatives for next-generation photovoltaics. However, sluggish charge extraction at CsPbX 3 /charge-transporting material interfaces, which arises from large interfacial energy differences, have markedly limited the further enhancement of solar cell performance. In this work, the work function (WF) of the back electrode is tuned by doping alloyed PtNi nanowires in carbon ink to promote hole extraction from CsPbBr 3 halides, while an intermediate energy by setting carbon quantum dots (CQDs) at TiO 2 /CsPbBr 3 interface bridges electron transportation. The preliminary results demonstrate that the matching WFs and intermediate energy level markedly reduce charge recombination. A power conversion efficiency of 7.17 % is achieved for the WF-tuned all-inorganic perovskite solar cell, in comparison with 6.10 % for the pristine device, and this is further increased to 7.86 % by simultaneously modifying with CQDs. The high efficiency and improved stability make WF-controlled all-inorganic perovskite solar cells promising to develop advanced photovoltaic platforms. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Mechanical control of magnetism in oxygen deficient perovskite SrTiO3.

    Science.gov (United States)

    Zhang, Yajun; Wang, Jie; Sahoo, M P K; Shimada, Takahiro; Kitamura, Takayuki

    2015-10-28

    Mechanical control of magnetism in perovskite oxides is an important and promising approach in spintronics. Based on the first-principles calculations, we demonstrate that a negative pressure leads to a great enhancement of magnetic moment in deficient SrTiO3 with oxygen vacancies, whereas a positive pressure results in the gradual disappearance of magnetism. Spin charge density, Bader charge analysis and electronic density of states successfully elucidate the origin and underlying physics of the enhancement and disappearance of magnetism. It is found that the split electronic states of dz(2), dyz and dzx in the 3d orbitals of Ti atoms remarkably contribute to the occupancy of majority spin states under negative pressure, which induces a large magnetic moment. Under positive pressure, however, the equal occupancy of both majority and minority t2g and eg states leads to the disappearance of magnetization. In addition, both negative and positive pressures can largely lower the vacancy formation enthalpy, suggesting that the oxygen vacancy is preferable with pressure. Our findings may provide a mechanism to achieve the pressure control of magnetization in nonmagnetic perovskite oxides.

  10. Large polarons in lead halide perovskites

    Science.gov (United States)

    Miyata, Kiyoshi; Meggiolaro, Daniele; Trinh, M. Tuan; Joshi, Prakriti P.; Mosconi, Edoardo; Jones, Skyler C.; De Angelis, Filippo; Zhu, X.-Y.

    2017-01-01

    Lead halide perovskites show marked defect tolerance responsible for their excellent optoelectronic properties. These properties might be explained by the formation of large polarons, but how they are formed and whether organic cations are essential remain open questions. We provide a direct time domain view of large polaron formation in single-crystal lead bromide perovskites CH3NH3PbBr3 and CsPbBr3. We found that large polaron forms predominantly from the deformation of the PbBr3− frameworks, irrespective of the cation type. The difference lies in the polaron formation time, which, in CH3NH3PbBr3 (0.3 ps), is less than half of that in CsPbBr3 (0.7 ps). First-principles calculations confirm large polaron formation, identify the Pb-Br-Pb deformation modes as responsible, and explain quantitatively the rate difference between CH3NH3PbBr3 and CsPbBr3. The findings reveal the general advantage of the soft [PbX3]− sublattice in charge carrier protection and suggest that there is likely no mechanistic limitations in using all-inorganic or mixed-cation lead halide perovskites to overcome instability problems and to tune the balance between charge carrier protection and mobility. PMID:28819647

  11. Synthesis, Resistivity, and Thermal Properties of the Cubic Perovskite NH 2CH=NH 2SnI 3and Related Systems

    Science.gov (United States)

    Mitzi, D. B.; Liang, K.

    1997-12-01

    Combining concentrated hydriodic acid solutions of tin(II) iodide and formamidine acetate in an inert atmosphere results in the precipitation of a new conducting organic-inorganic compound, NH 2CH=NH 2SnI 3, which at room temperature adopts a cubic perovskite structure. The lattice constant for NH 2CH=NH 2SnI 3is found to be a=6.316(1) Å, which is approximately 1.2% larger than that for the isostructural compound CH 3NH 3SnI 3. The electrical resistivity of a pressed pellet of the new compound exhibits semimetallic temperature dependence from 10 to 300 K, with evidence of a structural transition at approximately 75 K. NH 2CH=NH 2SnI 3begins to slowly decompose in an inert atmosphere at temperatures as low as 200°C, with bulk decomposition/melting occurring above 300°C. The properties of the formamidinium-based perovskite are compared with those of the related cubic (at room temperature) perovskite CH 3NH 3SnI 3and the mixed-cation system (CH 3NH 3) 1- x(NH 2CH=NH 2) xSnI 3.

  12. Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic-Inorganic Perovskites.

    Science.gov (United States)

    Sutter-Fella, Carolin M; Ngo, Quynh P; Cefarin, Nicola; Gardner, Kira L; Tamura, Nobumichi; Stan, Camelia V; Drisdell, Walter S; Javey, Ali; Toma, Francesca M; Sharp, Ian D

    2018-06-13

    Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long-term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. Here, we shed light on photoinduced halide demixing using in situ photoluminescence spectroscopy and in situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of composition and phase changes in CH(NH 2 ) 2 CsPb-halide (FACsPb-) and CH 3 NH 3 Pb-halide (MAPb-) perovskites upon illumination, thereby providing insights into why FACs-perovskites are less prone to halide demixing than MA-perovskites. We find that halide demixing occurs in both materials. However, the I-rich domains formed during demixing accumulate strain in FACsPb-perovskites but readily relax in MA-perovskites. The accumulated strain energy is expected to act as a stabilizing force against halide demixing and may explain the higher Br composition threshold for demixing to occur in FACsPb-halides. In addition, we find that while halide demixing leads to a quenching of the high-energy photoluminescence emission from MA-perovskites, the emission is enhanced from FACs-perovskites. This behavior points to a reduction of nonradiative recombination centers in FACs-perovskites arising from the demixing process and buildup of strain. FACsPb-halide perovskites exhibit excellent intrinsic material properties with photoluminescence quantum yields that are comparable to MA-perovskites. Because improved stability is achieved without sacrificing electronic properties, these compositions are better candidates for photovoltaic applications, especially as wide bandgap absorbers in tandem cells.

  13. Thickness-dependent nonlinear optical properties of CsPbBr3 perovskite nanosheets.

    Science.gov (United States)

    Zhang, Jun; Jiang, Tian; Zheng, Xin; Shen, Chao; Cheng, Xiang'ai

    2017-09-01

    Halide perovskite has attracted significant attention because of excellent optical properties. Here, we study the optical properties of CsPbBr 3 perovskite nanosheets and observe that the nonlinear optical properties can be tuned by the thickness. The photoluminescence (PL) properties and nonlinear absorption effects induced by saturation absorption (SA) and two-photon absorption (TPA) in CsPbBr 3 nanosheets with different thicknesses (from 104.6 to 195.4 nm) have been studied. The PL intensity increases nearly three times with changing from the thinnest one to the thinnest under the same excitation condition. Moreover, the same phenomenon takes place no matter when SA or TPA effects happen. The PL lifetime (τ) varies inversely with the thickness. When SA happens, τ decreases from 11.54 to 9.43 ns while when TPA happens new decay channels emerge with the increase of the thickness. Besides, both saturation intensity (I sat ) and the modulation depth are proportional to the thickness (I sat rises from 3.12 to 4.79  GW/cm 2 , the modulation depth increases from 18.6% to 32.3%), while the TPA coefficient (β) is inversely proportional with the thickness (decreases from 10.94 to 4.73  cm/GW). In addition, quantum yields and thicknesses are in the direct ratio. This Letter advocates great promise for nonlinear optical property related photonics devices.

  14. Two-Dimensional CH₃NH₃PbI₃ Perovskite: Synthesis and Optoelectronic Application.

    Science.gov (United States)

    Liu, Jingying; Xue, Yunzhou; Wang, Ziyu; Xu, Zai-Quan; Zheng, Changxi; Weber, Bent; Song, Jingchao; Wang, Yusheng; Lu, Yuerui; Zhang, Yupeng; Bao, Qiaoliang

    2016-03-22

    Hybrid organic-inorganic perovskite materials have received substantial research attention due to their impressively high performance in photovoltaic devices. As one of the oldest functional materials, it is intriguing to explore the optoelectronic properties in perovskite after reducing it into a few atomic layers in which two-dimensional (2D) confinement may get involved. In this work, we report a combined solution process and vapor-phase conversion method to synthesize 2D hybrid organic-inorganic perovskite (i.e., CH3NH3PbI3) nanocrystals as thin as a single unit cell (∼1.3 nm). High-quality 2D perovskite crystals have triangle and hexagonal shapes, exhibiting tunable photoluminescence while the thickness or composition is changed. Due to the high quantum efficiency and excellent photoelectric properties in 2D perovskites, a high-performance photodetector was demonstrated, in which the current can be enhanced significantly by shining 405 and 532 nm lasers, showing photoresponsivities of 22 and 12 AW(-1) with a voltage bias of 1 V, respectively. The excellent optoelectronic properties make 2D perovskites building blocks to construct 2D heterostructures for wider optoelectronic applications.

  15. Anharmonic stabilization and band gap renormalization in the perovskite CsSnI3

    DEFF Research Database (Denmark)

    Patrick, Christopher; Jacobsen, Karsten Wedel; Thygesen, Kristian Sommer

    2015-01-01

    Amongst the X(Sn,Pb)Y3 perovskites currently under scrutiny for their photovoltaic applications, the cubic B−α phase of CsSnI3 is arguably the best characterized experimentally. Yet, according to the standard harmonic theory of phonons, this deceptively simple phase should not exist at all due to...

  16. A Confined Fabrication of Perovskite Quantum Dots in Oriented MOF Thin Film.

    Science.gov (United States)

    Chen, Zheng; Gu, Zhi-Gang; Fu, Wen-Qiang; Wang, Fei; Zhang, Jian

    2016-10-26

    Organic-inorganic hybrid lead organohalide perovskites are inexpensive materials for high-efficiency photovoltaic solar cells, optical properties, and superior electrical conductivity. However, the fabrication of their quantum dots (QDs) with uniform ultrasmall particles is still a challenge. Here we use oriented microporous metal-organic framework (MOF) thin film prepared by liquid phase epitaxy approach as a template for CH 3 NH 3 PbI 2 X (X = Cl, Br, and I) perovskite QDs fabrication. By introducing the PbI 2 and CH 3 NH 3 X (MAX) precursors into MOF HKUST-1 (Cu 3 (BTC) 2 , BTC = 1,3,5-benzene tricarboxylate) thin film in a stepwise approach, the resulting perovskite MAPbI 2 X (X = Cl, Br, and I) QDs with uniform diameters of 1.5-2 nm match the pore size of HKUST-1. Furthermore, the photoluminescent properties and stability in the moist air of the perovskite QDs loaded HKUST-1 thin film were studied. This confined fabrication strategy demonstrates that the perovskite QDs loaded MOF thin film will be insensitive to air exposure and offers a novel means of confining the uniform size of the similar perovskite QDs according to the oriented porous MOF materials.

  17. Enhanced Size Selection in Two-Photon Excitation for CsPbBr3 Perovskite Nanocrystals.

    Science.gov (United States)

    Chen, Junsheng; Chábera, Pavel; Pascher, Torbjörn; Messing, Maria E; Schaller, Richard; Canton, Sophie; Zheng, Kaibo; Pullerits, Tõnu

    2017-10-19

    Cesium lead bromide (CsPbBr 3 ) perovskite nanocrystals (NCs), with large two-photon absorption (TPA) cross-section and bright photoluminescence (PL), have been demonstrated as stable two-photon-pumped lasing medium. With two-photon excitation, red-shifted PL spectrum and increased PL lifetime is observed compared with one-photon excitation. We have investigated the origin of such difference using time-resolved laser spectroscopies. We ascribe the difference to the enhanced size selection of NCs by two-photon excitation. Because of inherent nonlinearity, the size dependence of absorption cross-section under TPA is stronger. Consequently, larger size NCs are preferably excited, leading to longer excited-state lifetime and red-shifted PL emission. In a broad view, the enhanced size selection in two-photon excitation of CsPbBr 3 NCs is likely a general feature of the perovskite NCs and can be tuned via NC size distribution to influence their performance within NC-based nonlinear optical materials and devices.

  18. Directional Growth of Ultralong CsPbBr3 Perovskite Nanowires for High-Performance Photodetectors.

    Science.gov (United States)

    Shoaib, Muhammad; Zhang, Xuehong; Wang, Xiaoxia; Zhou, Hong; Xu, Tao; Wang, Xiao; Hu, Xuelu; Liu, Huawei; Fan, Xiaopeng; Zheng, Weihao; Yang, Tiefeng; Yang, Shuzhen; Zhang, Qinglin; Zhu, Xiaoli; Sun, Litao; Pan, Anlian

    2017-11-08

    Directional growth of ultralong nanowires (NWs) is significant for practical application of large-scale optoelectronic integration. Here, we demonstrate the controlled growth of in-plane directional perovskite CsPbBr 3 NWs, induced by graphoepitaxial effect on annealed M-plane sapphire substrates. The wires have a diameter of several hundred nanometers, with lengths up to several millimeters. Microstructure characterization shows that CsPbBr 3 NWs are high-quality single crystals, with smooth surfaces and well-defined cross section. The NWs have very strong band-edge photoluminescence (PL) with a long PL lifetime of ∼25 ns and can realize high-quality optical waveguides. Photodetectors constructed on these individual NWs exhibit excellent photoresponse with an ultrahigh responsivity of 4400 A/W and a very fast response speed of 252 μs. This work presents an important step toward scalable growth of high-quality perovskite NWs, which will provide promising opportunities in constructing integrated nanophotonic and optoelectronic systems.

  19. Development of 3d micro-nano hybrid patterns using anodized aluminum and micro-indentation

    International Nuclear Information System (INIS)

    Shin, Hong Gue; Kwon, Jong Tae; Seo, Young Ho; Kim, Byeong Hee

    2008-01-01

    We developed a simple and cost-effective method of fabricating 3D micro-nano hybrid patterns in which micro-indentation is applied on the anodized aluminum substrate. Nano-patterns were formed first on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns with a 150 nm-diameter on an aluminum substrate were fabricated by anodizing and alumina removing process. Then, micro-pyramid patterns with a side-length of 50 μm were formed on the nano-patterns using micro-indentation. To verify 3D micro-nano hybrid patterns, we replicated 3D micro-nano hybrid patterns by a hot-embossing process. 3D micro-nano hybrid patterns may be used in nano-photonic devices and nano-biochips applications

  20. Development of 3d micro-nano hybrid patterns using anodized aluminum and micro-indentation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hong Gue; Kwon, Jong Tae [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of); Seo, Young Ho [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)], E-mail: mems@kangwon.ac.kr; Kim, Byeong Hee [Division of Mechanical Engineering and Mechatronics, Kangwon National University, 1 Kangwondaehakgil, Chunchon, Gangwon-do, 200-701 (Korea, Republic of)

    2008-07-31

    We developed a simple and cost-effective method of fabricating 3D micro-nano hybrid patterns in which micro-indentation is applied on the anodized aluminum substrate. Nano-patterns were formed first on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns with a 150 nm-diameter on an aluminum substrate were fabricated by anodizing and alumina removing process. Then, micro-pyramid patterns with a side-length of 50 {mu}m were formed on the nano-patterns using micro-indentation. To verify 3D micro-nano hybrid patterns, we replicated 3D micro-nano hybrid patterns by a hot-embossing process. 3D micro-nano hybrid patterns may be used in nano-photonic devices and nano-biochips applications.

  1. Exciton Dynamics of 2D Hybrid Perovskite Nanocrystal

    Science.gov (United States)

    Guo, Rui; Zhu, Zhuan; Boulesbaa, Abdelaziz; Venkatesan, Swaminathan; Xiao, Kai; Bao, Jiming; Yao, Yan; Li, Wenzhi

    Organic-inorganic hybrid perovskites have emerged as promising materials for applications in photovoltaic and optoelectronic devices. Among the perovskites, two dimensional (2D) perovskites are of great interests due to their remarkable optical and electrical properties as well as the flexibility of material selection for the organic and inorganic moieties. In this study, we demonstrate the solution-phase growth of large square-shaped single-crystalline 2D hybrid perovskites of (C6H5C2H4 NH3) 2 PbBr4 with a few unit cells thickness. Compared to the bulk crystal, a band gap shift and new photoluminescence (PL) peak are observed from the hybrid perovskite sheets. Color of the 2D crystals can be tuned by adjusting the sheet thickness. Pump-probe spectroscopy is used to investigate the exciton dynamics and exhibits a biexponential decay with an amplitude-weighted lifetime of 16.7 ps. Such high-quality (C6H5C2H4 NH3) 2 PbBr4 sheets are expected to have high PL quantum efficiency which can be adopted for light-emitting devices. National Science Foundation (Grant No. CMMI-1334417 and DMR-1506640).

  2. Highly Luminescent Phase-Stable CsPbI3 Perovskite Quantum Dots Achieving Near 100% Absolute Photoluminescence Quantum Yield.

    Science.gov (United States)

    Liu, Feng; Zhang, Yaohong; Ding, Chao; Kobayashi, Syuusuke; Izuishi, Takuya; Nakazawa, Naoki; Toyoda, Taro; Ohta, Tsuyoshi; Hayase, Shuzi; Minemoto, Takashi; Yoshino, Kenji; Dai, Songyuan; Shen, Qing

    2017-10-24

    Perovskite quantum dots (QDs) as a new type of colloidal nanocrystals have gained significant attention for both fundamental research and commercial applications owing to their appealing optoelectronic properties and excellent chemical processability. For their wide range of potential applications, synthesizing colloidal QDs with high crystal quality is of crucial importance. However, like most common QD systems such as CdSe and PbS, those reported perovskite QDs still suffer from a certain density of trapping defects, giving rise to detrimental nonradiative recombination centers and thus quenching luminescence. In this paper, we show that a high room-temperature photoluminescence quantum yield of up to 100% can be obtained in CsPbI 3 perovskite QDs, signifying the achievement of almost complete elimination of the trapping defects. This is realized with our improved synthetic protocol that involves introducing organolead compound trioctylphosphine-PbI 2 (TOP-PbI 2 ) as the reactive precursor, which also leads to a significantly improved stability for the resulting CsPbI 3 QD solutions. Ultrafast kinetic analysis with time-resolved transient absorption spectroscopy evidence the negligible electron or hole-trapping pathways in our QDs, which explains such a high quantum efficiency. We expect the successful synthesis of the "ideal" perovskite QDs will exert profound influence on their applications to both QD-based light-harvesting and -emitting devices.

  3. A CsPbBr3 Perovskite Quantum Dot/Graphene Oxide Composite for Photocatalytic CO2 Reduction.

    Science.gov (United States)

    Xu, Yang-Fan; Yang, Mu-Zi; Chen, Bai-Xue; Wang, Xu-Dong; Chen, Hong-Yan; Kuang, Dai-Bin; Su, Cheng-Yong

    2017-04-26

    Halide perovskite quantum dots (QDs), primarily regarded as optoelectronic materials for LED and photovoltaic devices, have not been applied for photochemical conversion (e.g., water splitting or CO 2 reduction) applications because of their insufficient stability in the presence of moisture or polar solvents. Herein, we report the use of CsPbBr 3 QDs as novel photocatalysts to convert CO 2 into solar fuels in nonaqueous media. Under AM 1.5G simulated illumination, the CsPbBr 3 QDs steadily generated and injected electrons into CO 2 , catalyzing CO 2 reduction at a rate of 23.7 μmol/g h with a selectivity over 99.3%. Additionally, through the construction of a CsPbBr 3 QD/graphene oxide (CsPbBr 3 QD/GO) composite, the rate of electron consumption increased 25.5% because of improved electron extraction and transport. This study is anticipated to provide new opportunities to utilize halide perovskite QD materials in photocatalytic applications.

  4. Local Polar Fluctuations in Lead Halide Perovskite Crystals

    Science.gov (United States)

    Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

    2017-03-01

    Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3 NH3 PbBr3 ) and all-inorganic (CsPbBr3 ) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3 .

  5. Local Polar Fluctuations in Lead Halide Perovskite Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; Egger, David A.; Hull, Trevor; Stoumpos, Constantinos C.; Zheng, Fan; Heinz, Tony F.; Kronik, Leeor; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Rappe, Andrew M.; Pimenta, Marcos A.; Brus, Louis E.

    2017-03-01

    Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorganic (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-tohead Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.

  6. Electrochemical hydrogen property improved in nano-structured perovskite oxide LaFeO3 for Ni/MH battery

    Science.gov (United States)

    Wang, Qiang; Deng, Gang; Chen, Zhiqian; Chen, Yungui; Cheng, Nanpu

    2013-02-01

    Perovskite oxide LaFeO3, as a novel candidate for the electrode of Ni/MH battery, holds high specific capacity and good cyclical durability at elevated temperatures. However, the poor electrochemical kinetics is a bottleneck for the application of this type of material. By use of nano-structured materials, there are greatly enhanced values of exchange current density I0 and hydrogen diffusion coefficient D, which resulted in an improvement of electrochemical kinetics, a much higher specific capacity and excellent stability during cycling for nano-structured LaFeO3. In theory, there is a significant possibility of further advancing the hydrogen reaction kinetics of perovskite type oxides for Ni/MH battery.

  7. Highly Efficient Perovskite-Perovskite Tandem Solar Cells Reaching 80% of the Theoretical Limit in Photovoltage.

    Science.gov (United States)

    Rajagopal, Adharsh; Yang, Zhibin; Jo, Sae Byeok; Braly, Ian L; Liang, Po-Wei; Hillhouse, Hugh W; Jen, Alex K-Y

    2017-09-01

    Organic-inorganic hybrid perovskite multijunction solar cells have immense potential to realize power conversion efficiencies (PCEs) beyond the Shockley-Queisser limit of single-junction solar cells; however, they are limited by large nonideal photovoltage loss (V oc,loss ) in small- and large-bandgap subcells. Here, an integrated approach is utilized to improve the V oc of subcells with optimized bandgaps and fabricate perovskite-perovskite tandem solar cells with small V oc,loss . A fullerene variant, Indene-C 60 bis-adduct, is used to achieve optimized interfacial contact in a small-bandgap (≈1.2 eV) subcell, which facilitates higher quasi-Fermi level splitting, reduces nonradiative recombination, alleviates hysteresis instabilities, and improves V oc to 0.84 V. Compositional engineering of large-bandgap (≈1.8 eV) perovskite is employed to realize a subcell with a transparent top electrode and photostabilized V oc of 1.22 V. The resultant monolithic perovskite-perovskite tandem solar cell shows a high V oc of 1.98 V (approaching 80% of the theoretical limit) and a stabilized PCE of 18.5%. The significantly minimized nonideal V oc,loss is better than state-of-the-art silicon-perovskite tandem solar cells, which highlights the prospects of using perovskite-perovskite tandems for solar-energy generation. It also unlocks opportunities for solar water splitting using hybrid perovskites with solar-to-hydrogen efficiencies beyond 15%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Dielectric behaviour of (Ba,Sr)TiO3 perovskite borosilicate glass ceramics

    International Nuclear Information System (INIS)

    Yadav, Avadhesh Kumar; Gautam, C.R.

    2013-01-01

    Various perovskite (Ba,Sr)TiO 3 borosilicate glasses were prepared by rapid melt-quench technique in the glass system ((Ba 1-x Sr x ).TiO 3 )-(2SiO 2 .B 2 O 3 )-(K 2 O)-(La 2 O 3 ). On the basis of differential thermal analysis results, glasses were converted into glass ceramic samples by regulated heat treatment schedules. The dielectric behaviour of crystallized barium strontium titanate borosilicate glass ceramic samples shows diffuse phase transition. The study depicts the dielectric behaviour of glass ceramic sample BST5K1L0.2S814. The double relaxation was observed in glass ceramic samples corresponding 80/20% Ba/Sr due to change in crystal structure from orthorhombic to tetragonal and tetragonal to cubic with variation of temperature. The highest value of dielectric constant was found to be 48289 for the glass ceramic sample BST5K1L0.2S814. The high value of dielectric constant attributed to space charge polarization between the glassy phase and perovskite phase. Due to very high value of dielectric constant, such glass ceramics are used for high energy storage devices. La 2 O 3 acts as nucleating agent for crystallization of glass to glass ceramics and enhances the dielectric constant and retarded dielectric loss. Such glass ceramics can be used in high energy storage devices such as barrier layer capacitors, multilayer capacitors etc. (author)

  9. Strong Photonic-Band-Gap Effect on the Spontaneous Emission in 3D Lead Halide Perovskite Photonic Crystals.

    Science.gov (United States)

    Zhou, Xue; Li, Mingzhu; Wang, Kang; Li, Huizeng; Li, Yanan; Li, Chang; Yan, Yongli; Zhao, Yongsheng; Song, Yanlin

    2018-03-25

    Stimulated emission in perovskite-embedded polymer opal structures is investigated. A polymer opal structure is filled with a perovskite, and perovskite photonic crystals are prepared. The spontaneous emission of the perovskite embedded in the polymer opal structures exhibits clear signatures of amplified spontaneous emission (ASE) via gain modulation. The difference in refractive-index contrast between the perovskite and the polymer opal is large enough for retaining photonic-crystals properties. The photonic band gap has a strong effect on the fluorescence emission intensity and lifetime. The stimulated emission spectrum exhibits a narrow ASE rather than a wide fluorescence peak in the thin film. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Zero-Dimensional Cs4PbBr6 Perovskite Nanocrystals

    KAUST Repository

    Zhang, Yuhai

    2017-02-09

    Perovskite nanocrystals (NCs) have become leading candidates for solution-processed optoelectronics applications. While substantial work has been published on 3-D perovskite phases, the NC form of the zero-dimensional (0-D) phase of this promising class of materials remains elusive. Here we report the synthesis of a new class of colloidal semiconductor NCs based on Cs4PbBr6, the 0-D perovskite, enabled through the design of a novel low-temperature reverse microemulsion method with 85% reaction yield. These 0-D perovskite NCs exhibit high photoluminescence quantum yield (PLQY) in the colloidal form (PLQY: 65%), and, more importantly, in the form of thin film (PLQY: 54%). Notably, the latter is among the highest values reported so far for perovskite NCs in the solid form. Our work brings the 0-D phase of perovskite into the realm of colloidal NCs with appealingly high PLQY in the film form, which paves the way for their practical application in real devices.

  11. Preparation and characterization of a layered perovskite-type organic-inorganic hybrid compound (C8NH6-CH2CH2NH3)2CuCl4

    International Nuclear Information System (INIS)

    Zheng Yingying; Wu Gang; Deng Meng; Chen Hongzheng; Wang Mang; Tang, B.-Z.

    2006-01-01

    The organic-inorganic hybrid compound (C 8 NH 6 -CH 2 CH 2 NH 3 ) 2 CuCl 4 (AEI-CuCl 4 ) was synthesized from ethanol solution containing copper chloride and 3-2-(aminoethyl) indole hydrochloride (AEI-HCl). High order diffraction peaks corresponding to (0 0 l; l = 2, 4, 6, ...) observed in the X-ray diffraction profile of AEI-CuCl 4 indicated the formation of hybrid crystal with layered perovskite structure. The organic-inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the AEI-CuCl 4 perovskite and it showed characteristic absorptions of CuCl-based layered perovskite centered at 288 and 388 nm, as well as the photoluminescence peak at around 420 nm. The unaided-eye-detectable blue fluorescence emission comes from the cooperation of AEI-HCl and AEI-CuCl 4 perovskite, in which protonized aminoethyl indole dominates the shape of the spectrum and the enhancement of emission intensity is due to the formation of the perovskite structure. The thermal analysis presented that the AEI-CuCl 4 perovskite started to melt at 182 deg. C, together with the beginning of the decomposition of the hybrids. Compared with the organic-inorganic perovskite hybrids reported previously, the AEI-CuCl 4 perovskite shows a novel stepwise decomposition behavior

  12. Light-trapping in perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Qing Guo Du

    2016-06-01

    Full Text Available We numerically demonstrate enhanced light harvesting efficiency in both CH3NH3PbI3 and CH(NH22PbI3-based perovskite solar cells using inverted vertical-cone photonic-crystal nanostructures. For CH3NH3PbI3 perovskite solar cells, the maximum achievable photocurrent density (MAPD reaches 25.1 mA/cm2, corresponding to 92% of the total available photocurrent in the absorption range of 300 nm to 800 nm. Our cell shows 6% absorption enhancement compared to the Lambertian limit (23.7 mA/cm2 and has a projected power conversion efficiency of 12.9%. Excellent solar absorption is numerically demonstrated over a broad angular range from 0 to 60 degree for both S- and P- polarizations. For the corresponding CH(NH22PbI3 based perovskite solar cell, with absorption range of 300 nm to 850 nm, we find a MAPD of 29.1 mA/cm2, corresponding to 95.4% of the total available photocurrent. The projected power conversion efficiency of the CH(NH22PbI3 based photonic crystal solar cell is 23.4%, well above the current world record efficiency of 20.1%.

  13. Electroless Growth of Aluminum Dendrites in NaCl-AlCl3 Melts

    DEFF Research Database (Denmark)

    Li, Qingfeng; Hjuler, H.A.; Berg, Rolf W.

    1989-01-01

    The spontaneous growth of aluminum dendrites after deposition was observed and examined in sodium chloride-aluminumchloride melts. The concentration gradient of AlCl3 in the vicinity of the cathode surface resulting from electrolysisconstitutes a type of concentration cell with aluminum dendrites...... as electrodes. The short-circuit discharge of thecell is found to be the driving force for the growth of aluminum dendrites. Such a concentration gradient is proposed to beone of the causes for dendrite formation in the case of metal deposition....

  14. LSFM perovskites as cathodes for the electrochemical reduction of NO

    DEFF Research Database (Denmark)

    Kammer Hansen, K.; Skou, E.M.

    2005-01-01

    Six La0.6Sr0.4Fe1-xMnO3-delta (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskite compounds have been synthesised by the citric-acid route. The perovskites have been characterised by powder XRD and are shown to belong to the hexagonal crystal system. The perovskites are also evaluated by TG...... degrees C on a ceria based electrolyte. Only La0.6Sr0.4Fe0.8Mn0.2O3-delta (LSFM020) and La0.6Sr0.4FeO3-delta (LSFM000) show significant activity for the reduction of NO. This can probably be related to the high redox capacity of these compounds. The activity of the perovskites for the reduction of oxygen...... increases systematically with increasing iron content. The selectivity of the perovskites towards the reduction of NO with regard to the reduction of O-2 is highest at the lowest temperatures. (c) 2004 Published by Elsevier B.V....

  15. Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

    DEFF Research Database (Denmark)

    Tang, Yingying; Cao, Xianyi; Chi, Qijin

    2018-01-01

    Compared to their conventional three-dimensional (3D) counterparts, two-dimensional (2D) halide perovskites have attracted more interests recently in a variety of areas related to optoelectronics because of their unique structural characteristics and enhanced performances. In general, there are two...... distinct types of 2D halide perovskites. One represents those perovskites with an intrinsic layered crystal structure (i.e. MX6 layers, M = metal and X = Cl, Br, I), the other defines the perovskites with a 2D nanostructured morphology such as nanoplatelets and nanosheets. Recent studies have shown that 2D...... halide perovskites hold promising potential for the development of new-generation photodetectors, mainly arising from their highly efficient photoluminescence and absorbance, color tunability in the visible-light range and relatively high stability. In this chapter, we present the summary and highlights...

  16. Crystallization of perovskite film using ambient moisture and water as co-solvent for efficient planar perovskite solar cell (Conference Presentation)

    Science.gov (United States)

    Dubey, Ashish; Reza, Khan M.; Gaml, Eman; Adhikari, Nirmal; Qiao, Qiquan

    2016-09-01

    Smooth, compact and defect free morphology of perovskite is highly desired for enhanced device performance. Several routes such as thermal annealing, use of solvent mixtures, growth under controlled humidity has been adopted to obtain crystalline, smooth and defect free perovskite film. Herein we showed direct use of water (H2O) as co-solvent in precursor solution and have optimized the water content required to obtain smooth and dense film. Varying concentration of water was used in precursor solution of CH3NH3I and PbI2 mixed in γ-butyrolactone (GBL) and dimethylsulfoxide (DMSO). Perovskite films were crystallized using toluene assisted solvent engineering method using GBL:DMSO:H2O as solvent mixture. The amount of water was varied from 1% to 25%, which resulted in change in film morphology and perovskite crystallinity. It was concluded that an appropriate amount of water is required to assist the crystallization process to obtain smooth pin-hole free morphology. The change in morphology led to improved fill factor in the device, with highest efficiency 14%, which was significantly higher than devices made from perovskite film without adding water. We also showed that addition of up to 25% by volume of water does not significantly change the device performance.

  17. DFT analysis and FDTD simulation of CH3NH3PbI3-x Cl x mixed halide perovskite solar cells: role of halide mixing and light trapping technique

    Science.gov (United States)

    Saffari, Mohaddeseh; Mohebpour, Mohammad Ali; Rahimpour Soleimani, H.; Bagheri Tagani, Meysam

    2017-10-01

    Since perovskite solar cells have attracted a great deal of attention over the past few years, the enhancement of their optical absorption and current density are among the basic upcoming challenges. For this reason, first, we have studied the structural and optical properties of organic-inorganic hybrid halide perovskite CH3NH3PbI3 and the compounds doped by chlorine halogen CH3NH3PbI3-x Cl x in the cubic phase by using a density functional theory (DFT). Then, we model a single-junction perovskite solar cell based on a full solution to Maxwell’s equations, using a finite difference time domain (FDTD) technique, which helps us to investigate the light absorption efficiency and optical current density of the cell with CH3NH3PbI3-x Cl x (x  =  0, 1, 2, 3) as the active layer. The results suggest that increasing the amount of chlorine in CH3NH3PbI3-x Cl x compound leads to an increase in the bandgap energy, as well as a decrease in the lattice constants and optical properties, like the refractive index and extinction coefficient of the structure. Also, the results obtained by the simulation express that by taking advantage of the light trapping techniques of SiO2, a remarkable increase of light absorption will be achieved to the magnitude of 83.13%, which is noticeable.

  18. Calculated high-pressure structural properties, lattice dynamics and quasi particle band structures of perovskite fluorides KZnF3, CsCaF3 and BaLiF3.

    Science.gov (United States)

    Vaitheeswaran, G; Kanchana, V; Zhang, Xinxin; Ma, Yanming; Svane, A; Christensen, N E

    2016-08-10

    A detailed study of the high-pressure structural properties, lattice dynamics and band structures of perovskite structured fluorides KZnF3, CsCaF3 and BaLiF3 has been carried out by means of density functional theory. The calculated structural properties including elastic constants and equation of state agree well with available experimental information. The phonon dispersion curves are in good agreement with available experimental inelastic neutron scattering data. The electronic structures of these fluorides have been calculated using the quasi particle self-consistent [Formula: see text] approximation. The [Formula: see text] calculations reveal that all the fluorides studied are wide band gap insulators, and the band gaps are significantly larger than those obtained by the standard local density approximation, thus emphasizing the importance of quasi particle corrections in perovskite fluorides.

  19. First principles investigation of half-metallicity and spin gapless semiconductor in CH3NH3Cr x Pb1- x I3 mixed perovskites

    Science.gov (United States)

    Huang, H. M.; Zhu, Z. W.; Zhang, C. K.; He, Z. D.; Luo, S. J.

    2018-04-01

    The structural, electronic and magnetic properties of organic-inorganic hybrid mixed perovskites CH3NH3Cr x Pb1- x I3 ( x = 0.25, 0.50, 0.75, 1.00) in cubic, tetragonal and orthorhombic phases have been investigated by first-principles calculation. The results indicate that the tetragonal CH3NH3Cr0.75Pb0.25I3 is a spin gapless semiconductor with Curie temperature of 663 K estimated using mean field approximation. All other CH3NH3Cr x Pb1- x I3 mixed perovskites are half-metallic ferromagnets together with 100% spin polarization, and their total magnetic moment are 4.00, 8.00, 12.00 and 16.00 µB per unit cell for x = 0.25, 0.50, 0.75 and 1.00, respectively. The effect of , and orientation of organic cation CH3NH3 + on the electronic properties of CH3NH3Cr0.50Pb0.50I3 was investigated. The results show that the CH3NH3 + in different orientations have a slight effect on the lattice constants, the energy gap in minority-spin states, half-metallic gap, local magnetic moment, and Curie temperature.

  20. Structural, optical and morphological studies of Cd2+ doping in CH3NH3PbI3 perovskite semiconductor at Pb2+ site for photovoltaic applications

    Science.gov (United States)

    Parrey, Khursheed; Warish, Mohd.; Devi, Nisha; Niazi, A.; Aziz, A.; Ansari, S. G.

    2018-05-01

    Doping of semiconductors in a controlled mannner have paramount technological importance as far as the optical and electronic properties of the devices are concerned. Hybrid organic-inorganic perovskites (HOPs) as intrinsic semiconductors have sensational properties required for both the solar photovoltaics and perovskite light emitting diodes. However, undoped and complexity in the dpoing process of HOPs have limited their exploitation in the field of elcronics. In this papper we present the synthesis of HOP semiconductor (CH3NH3PbI3) doped in Pb2+ position by Cd2+. We studied the effect of the incorporation of Cd2+ into the crystalline structure and analysed the changes in the properties like crystal structure, optical absorption and the surface morphology. The structure of HOPs confirmed by X-ray diffraction analysis is tetragonal perovskite type. It can be found that the crystallinity of the samples was enhanced with the doping concentration as the intensity of diffraction peaks were observed to increase with doping. The absorption spectra as obtained from UV-Visible spectrophotometry and Tauc plot analysis indicated that the band gap observed (1.73 eV) is direct type and gets reduced to 1.67 eV with the doping concentration. The red shift may be due to the increase in the size of nanocrystalline material with doping.

  1. A versatile light-switchable nanorod memory: Wurtzite ZnO on perovskite SrTiO3

    KAUST Repository

    Kumar, Anup Bera; Peng, Haiyang; Lourembam, James; Shen, Youde; Sun, Xiaowei; Wu, Tao

    2013-01-01

    heterojunction memory made of wurtzite ZnO nanorods grown on perovskite Nb-doped SrTiO3 (NSTO) is reported, the electronic properties of which can be drastically reconfigured by applying a voltage and light. Despite of the distinct lattice structures of Zn

  2. Ab initio Defect Energetics in LaBO3 Perovskite Solid Oxide Fuel Cell Materials

    DEFF Research Database (Denmark)

    Lee, Yueh-Lin; Morgan, Dane; Kleis, Jesper

    2009-01-01

    Perovskite materials of the form ABO3 are a promising family of compounds for use in solid oxide fuel cell (SOFC) cathodes. Study of the physics of these compounds under SOFC conditions with ab initio methods is particularly challenging due to high temperatures, exchange of oxygen with O2 gas...

  3. Hexagonal perovskites with cationic vacancies. 4. Ba/sub 8/Re/sub 3/Msup(V)Wvacant/sub 3/O/sub 24/ with Msup(V) = Nb, Ta - perovskite stacking polytypes of 24 L type

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-11-01

    The yellow perovskite stacking polytypes Ba/sub 8/Re/sub 3/NbWvacant/sub 3/O/sub 24/ and Ba/sub 8/Re/sub 3/TaWvacant/sub 3/O/sub 24/ have a rhombohedral layer structure of 24 L type with 3 formula units in the trigonal setting (Ba/sub 8/Re/sub 3/NbWvacant/sub 3/O/sub 24/: a = 5,82 A; c = 55.6 A; Ba/sub 8/Re/sub 3/TaWvacant/sub 3/O/sub 24/; a = 5,81 A; c = 55.6 A).

  4. Spontaneous emission enhancement of colloidal perovskite nanocrystals

    Science.gov (United States)

    Yang, Zhili; Waks, Edo

    Halide perovskite semiconductors have emerged as prominent photovoltaic materials since their high conversion efficiency and promising light emitting materials in optoelectronics. In particular, easy-to-fabricated colloidal perovskite nanocrystals based on CsPbX3 quantum dots has been intensively investigated recently. Their luminescent wavelength could be tuned precisely by their chemical composition and size of growth. This opens new applications including light-emitting diodes, optical amplifiers and lasing since their promising performance as emitters. However, this potentially high-efficient emitter and gain material has not been fully investigated and realized in integrated photonic structures. Here we demonstrate Purcell enhancement effect of CsPbBr3 perovskite nanocrystals by coupling to an optimized photonic crystal nanobeam cavity as a first crucial step towards realization of integrated on-chip coherent light source with low energy consumption. We show clearly highly-enhanced photoluminescent spectrum and an averaged Purcell enhancement factor of 2.9 is achieved when they are coupled to nanobeam photonic crystal cavities compared to the ones on unpatterned surface in our lifetime measurement. Our success in enhancement of emission from CsPbX3 perovskite nanocrystals paves the way towards the realization of efficient light sources for integrated optoelectronic devices with low energy consumption.

  5. High-throughput DFT calculations of formation energy, stability and oxygen vacancy formation energy of ABO3 perovskites

    Science.gov (United States)

    Emery, Antoine A.; Wolverton, Chris

    2017-10-01

    ABO3 perovskites are oxide materials that are used for a variety of applications such as solid oxide fuel cells, piezo-, ferro-electricity and water splitting. Due to their remarkable stability with respect to cation substitution, new compounds for such applications potentially await discovery. In this work, we present an exhaustive dataset of formation energies of 5,329 cubic and distorted perovskites that were calculated using first-principles density functional theory. In addition to formation energies, several additional properties such as oxidation states, band gap, oxygen vacancy formation energy, and thermodynamic stability with respect to all phases in the Open Quantum Materials Database are also made publicly available. This large dataset for this ubiquitous crystal structure type contains 395 perovskites that are predicted to be thermodynamically stable, of which many have not yet been experimentally reported, and therefore represent theoretical predictions. The dataset thus opens avenues for future use, including materials discovery in many research-active areas.

  6. Shape-controlled synthesis of organolead halide perovskite nanocrystals and their tunable optical absorption

    International Nuclear Information System (INIS)

    Chen, Zhenhua; Tang, Yongbing; Huang, Xing; Lee, Chun-Sing; Li, Hui; Ho, Derek

    2014-01-01

    Hybrid organolead halide perovskites (CH 3 NH 3 PbI 3 ) with polymorphic structures have been successfully synthesized by controlling their solubility in solvents with different polarities. Crystal formation stages of the perovskites have been demonstrated for the first time. Shape changes of such perovskites are accompanied by transition in their crystal structures and variation of optical properties. Herein, a new trigonal phase for CH 3 NH 3 PbI 3 has been observed with a rod-like morphology. Photoemission study indicates a significant red shift in the perovskite nanoparticles, compared to that of the rod-like nanocrystals. This solvent-controlled formation of polymorphic phases provide an additional approach for controlling the optical properties of CH 3 NH 3 PbI 3 for various optoelectronic applications. (papers)

  7. Electronic and optical properties of MAPbX3 perovskites (X = I, Br, Cl): a unified DFT and GW theoretical analysis.

    Science.gov (United States)

    Mosconi, Edoardo; Umari, Paolo; De Angelis, Filippo

    2016-10-05

    Materials engineering is a key for the enhancement of photovoltaics technology. This is particularly true for the novel class of perovskite solar cells. Accurate theoretical modelling can help establish general trends of behavior when addressing structural changes. Here, we consider the effects due to halide substitution in organohalide CH 3 NH 3 PbX 3 perovskites exploring the halide series with X = Cl, Br, I. For this task, we use accurate DFT and GW methods including spin-orbit coupling. We find the expected band gap increase when moving from X = I to Cl, in line with the experimental data. Most notably, the calculated absorption coefficients for I, Br and Cl are nicely reproducing the behavior reported experimentally. A common feature of all the simulated band structures is a significant Rashba effect. This is similar for MAPbI 3 and MAPbBr 3 while MAPbCl 3 shows in general a reduced Rashba interaction coefficient. Finally, a monotonic increase of the exciton reduced masses is calculated when moving from I to Br to Cl, in line with the stronger excitonic character of the lighter perovskite halides.

  8. High-efficiency near-infrared enabled planar perovskite solar cells by embedding upconversion nanocrystals.

    Science.gov (United States)

    Meng, Fan-Li; Wu, Jiao-Jiao; Zhao, Er-Fei; Zheng, Yan-Zhen; Huang, Mei-Lan; Dai, Li-Ming; Tao, Xia; Chen, Jian-Feng

    2017-11-30

    Integration of the upconversion effect in perovskite solar cells (PSCs) is a facile approach towards extending the spectral absorption from the visible to the near infrared (NIR) range and reducing the non-absorption loss of solar photons. However, the big challenge for practical application of UCNCs in planar PSCs is the poor compatibility between UCNCs and the perovskite precursor. Herein, we have subtly overcome the tough compatibility issue using a ligand-exchange strategy. For the first time, β-NaYF 4 :Yb,Er UCNCs have been embedded in situ into a CH 3 NH 3 PbI 3 layer to fabricate NIR-enabled planar PSCs. The CH 3 NH 3 I-capped UCNCs generated from the ligand-exchange were mixed with the perovskite precursor and served as nucleation sites for the UCNC-mediated heteroepitaxial growth of perovskite; moreover, the in situ embedding of UCNCs into the perovskite layer was realized during a spin-coating process. The resulting UCNC-embedded perovskite layer attained a uniform pinhole-free morphology with enlarged crystal grains and enabled NIR absorption. It also contributed to the energy transfer from the UCNCs to the perovskite and electron transport to the collecting electrode surface. The device fabricated using the UCNC-embedded perovskite film achieved an average power-conversion efficiency of 18.60% (19.70% for the best) under AM 1.5G and 0.37% under 980 nm laser, corresponding to 54% and 740-fold increase as compared to that of its counterpart without UCNCs.

  9. Enhanced planar perovskite solar cell efficiency and stability using a perovskite/PCBM heterojunction formed in one step.

    Science.gov (United States)

    Zhou, Long; Chang, Jingjing; Liu, Ziye; Sun, Xu; Lin, Zhenhua; Chen, Dazheng; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

    2018-02-08

    Perovskite/PCBM heterojunctions are efficient for fabricating perovskite solar cells with high performance and long-term stability. In this study, an efficient perovskite/PCBM heterojunction was formed via conventional sequential deposition and one-step formation processes. Compared with conventional deposition, the one-step process was more facile, and produced a perovskite thin film of substantially improved quality due to fullerene passivation. Moreover, the resulting perovskite/PCBM heterojunction exhibited more efficient carrier transfer and extraction, and reduced carrier recombination. The perovskite solar cell device based on one-step perovskite/PCBM heterojunction formation exhibited a higher maximum PCE of 17.8% compared with that from the conventional method (13.7%). The device also showed exceptional stability, retaining 83% of initial PCE after 60 days of storage under ambient conditions.

  10. High-pressure behavior of methylammonium lead iodide (MAPbI_3) hybrid perovskite

    International Nuclear Information System (INIS)

    Capitani, Francesco; Marini, Carlo; Caramazza, Simone; Postorino, Paolo; Garbarino, Gaston; Hanfland, Michael; Pisanu, Ambra; Quadrelli, Paolo; Malavasi, Lorenzo

    2016-01-01

    In this paper we provide an accurate high-pressure structural and optical study of the MAPbI_3 hybrid perovskite. Structural data show the presence of a phase transition toward an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing the pressure, the system keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition.

  11. High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid perovskite

    Science.gov (United States)

    Capitani, Francesco; Marini, Carlo; Caramazza, Simone; Postorino, Paolo; Garbarino, Gaston; Hanfland, Michael; Pisanu, Ambra; Quadrelli, Paolo; Malavasi, Lorenzo

    2016-05-01

    In this paper we provide an accurate high-pressure structural and optical study of the MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition toward an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing the pressure, the system keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition.

  12. Electronically conductive perovskite-based oxide nanoparticles and films for optical sensing applications

    Science.gov (United States)

    Ohodnicki, Jr., Paul R; Schultz, Andrew M

    2015-04-28

    The disclosure relates to a method of detecting a change in a chemical composition by contacting a electronically conducting perovskite-based metal oxide material with a monitored stream, illuminating the electronically conducting perovskite-based metal oxide with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The electronically conducting perovskite-based metal oxide has a perovskite-based crystal structure and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The electronically conducting perovskite-based metal oxide has an empirical formula A.sub.xB.sub.yO.sub.3-.delta., where A is at least a first element at the A-site, B is at least a second element at the B-site, and where 0.8perovskite-based oxides include but are not limited to La.sub.1-xSr.sub.xCoO.sub.3, La.sub.1-xSr.sub.xMnO.sub.3, LaCrO.sub.3, LaNiO.sub.3, La.sub.1-xSr.sub.xMn.sub.1-yCr.sub.yO.sub.3, SrFeO.sub.3, SrVO.sub.3, La-doped SrTiO.sub.3, Nb-doped SrTiO.sub.3, and SrTiO.sub.3-.delta..

  13. Studies on perovskite film ablation and scribing with ns-, ps- and fs-laser pulses

    Science.gov (United States)

    Bayer, Lukas; Ye, Xinyuan; Lorenz, Pierre; Zimmer, Klaus

    2017-10-01

    Hybrid organic-inorganic perovskites attract much attention due to their exceptional optoelectronic properties, in particular for photovoltaic (PV) applications. The accurate, high-speed and reliable patterning of the PV films is required for perovskite solar modules fabrication. Laser scribing provides these characteristics needed for industrial fabrication processes. In this work, the laser ablation and scribing of perovskite layers (CH3NH3PbI3: MAPbI3) with different laser sources (ns-, ps-, fs-laser pulses with wavelengths of 248 nm to 2.5 µm) were systematically investigated. The perovskite material was irradiated from both the film side and the substrate (rear side) side to study and compare the particular processes. The patterning results of the perovskite film can be classified into (1) regular laser ablation, (2) thin-film delamination lift-off process, and (3) lift-off with thermal modifications. A particular process, the localised lift-off of single grains from the perovskite film, has been observed and is discussed in relation to the thin-film lift-off process. Ablation and ablation-related mechanisms provide good conditions for laser scribing of the perovskite layer required for module interconnection via P2.

  14. Controlled synthesis of quantum confined CsPbBr3 perovskite nanocrystals under ambient conditions

    Science.gov (United States)

    He, Huimei; Tang, Bing; Ma, Ying

    2018-02-01

    Room temperature recrystallization is a simple and convenient method for synthesis of all-inorganic perovskite nanomaterials with excellent luminescent properties. However, the fast crystallization usually brings the colloidal stability and uncontrollable synthesis issues in the formation of all-inorganic perovskite. In the present study, we present a new strategy to prepare the quantum confined CsPbBr3 nanocrystals with controlled morphology under ambient condition. With the assist of fatty acid-capped precursor, the crystallization and the following growth rate can be retarded. Thanks to the retarded reaction, the morphology can be varied from nanowires to nanoplates and the thickness can be controlled from 5-7 monolayers by simply adjusting the amount of octylammonium cations and oleic acid. The nanoplates exhibit a higher photoluminescence quantum yield than the nanowires possibly due to fewer defects in the nanoplates.

  15. Controlled Synthesis of Quantum Confined CsPbBr3 perovskite Nanocrystals under Ambient Condition.

    Science.gov (United States)

    He, Huimei; Tang, Bing; Ma, Ying

    2017-11-21

    Room temperature recrystallization is a simple and convenient method for synthesis of all-inorganic perovskite nanomaterials with excellent luminescent properties. However, the fast crystallization usually brings the colloidal stability and uncontrollable synthesis issues in the formation of all-inorganic perovskite. In the present study, we present a new strategy to prepare the quantum confined CsPbBr3 nanocrystals with controlled morphology under ambient condition. With the assist of fatty acid-capped precursor, the crystallization and the following growth rate can be retarded. Thanks to the retarded reaction, the morphology can be varied from nanowires to nanoplates and the thickness can be controlled from 5 to 7 monolayers by simply adjusting the amount of octylammonium cations and oleic acid. The nanoplates exhibit a higher photoluminescence quantum yield than the nanowires possibly due to fewer defects in the nanoplates. © 2017 IOP Publishing Ltd.

  16. Crystal structure and lithium ion conductivity of A-site deficient perovskites La1/3-xLi3xTaO3

    International Nuclear Information System (INIS)

    Mizumoto, Katsuyoshi; Hayashi, Shinsuke

    1997-01-01

    The crystal structure and lithium ion conductivity of La 1/3-x Li 3x TaO 3 solid solutions with the A-site deficient perovskite structure have been studied. Single phase solid solutions were obtained in the range of x=0 to 1/6. Change from tetragonal to cubic structure and decrease in the lattice volume were observed with increasing the x value. The maximum conductivity obtained was 7 x 10 -3 S·m -1 at x=0.06. The composition-dependence on the carrier concentration was calculated and compared with conductivity data. (author)

  17. Modulation of electronic and optical properties in mixed halide perovskites CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x)

    Science.gov (United States)

    Zhou, Ziqi; Cui, Yu; Deng, Hui-Xiong; Huang, Le; Wei, Zhongming; Li, Jingbo

    2017-03-01

    The recent discovery of lead halide perovskites with band gaps in the visible presents important potential in the design of high efficient solar cells. CsPbCl3, CsPbBr3 and CsPbI3 are stable compounds within this new family of semiconductors. By performing the first-principles calculation, we explore the structural, electronic and optical properties of CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with various compositions of halide atoms. Structural stability is demonstrated with halide atoms distributing randomly at the halide atomic sites. CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) exhibit the modulation of their band gaps by varying the halide composition. Our results also indicate that CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with different halide compositions are suitable to application to solar cells for the general features are well preserved. Good absorption to lights of different wavelengths has been obtained in these mixed halide perovskites.

  18. Fabrication and characterization of perovskite-based CH{sub 3}NH{sub 3}Pb{sub 1-x}Ge{sub x}I{sub 3}, CH{sub 3}NH{sub 3}Pb{sub 1-x}Tl{sub x}I{sub 3} and CH{sub 3}NH{sub 3}Pb{sub 1-x}In{sub x}I{sub 3} photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Ohishi, Yuya; Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Suzuki, Atsushi [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    Perovskite-type CH{sub 3}NH{sub 3}PbI{sub 3}-based photovoltaic devices were fabricated and characterized. Doping effects of thallium (Tl), indium (In), or germanium (Ge) element on the photovoltaic properties and surface structures of the perovskite phase were investigated. The open circuit voltage increased by Ge addition, and fill factors were improved by adding a small amount of Ge, Tl or In. In addition, the wavelength range of incident photon conversion efficiencies was expanded by the Tl addition.

  19. Thermochemical and thermophysical properties of alkaline-earth perovskites

    International Nuclear Information System (INIS)

    Yamanaka, Shinsuke; Kurosaki, Ken; Maekawa, Takuji; Matsuda, Tetsushi; Kobayashi, Shin-ichi; Uno, Masayoshi

    2005-01-01

    In order to contribute to safety evaluation of high burnup oxide fuels, we studied the thermochemical and thermophysical properties of alkaline-earth perovskites known as oxide inclusions. Polycrystalline samples of alkaline-earth perovskites, BaUO 3 , BaZrO 3 , BaCeO 3 , BaMoO 3 , SrTiO 3 , SrZrO 3 , SrCeO 3 , SrMoO 3 , SrHfO 3 and SrRuO 3 , were prepared and the thermal expansion coefficient, melting temperature, elastic moduli, Debye temperature, microhardness, heat capacity, and thermal conductivity were measured. The relationship between some physical properties was studied

  20. The Effect of Al on the Compressibility of Silicate Perovskite

    Science.gov (United States)

    Walter, M. J.; Kubo, A.; Yoshino, T.; Koga, K. T.; Ohishi, Y.

    2003-12-01

    Experimental data on compressibility of aluminous silicate perovskite show widely disparate results. Several studies show that Al causes a dramatic increase in compressibility1-3, while another study indicates a mild decrease in compressibility4. Here we report new results for the effect of Al on the room-temperature compressibility of perovskite using in situ X-ray diffraction in the diamond anvil cell from 30 to 100 GPa. We studied compressibility of perovskite in the system MgSiO3-Al2O3 in compositions with 0 to 25 mol% Al. Perovskite was synthesized from starting glasses using laser-heating in the DAC, with KBr as a pressure medium. Diffraction patterns were obtained using monochromatic radiation and an imaging plate detector at beamline BL10XU, SPring8, Japan. Addition of Al into the perovskite structure causes systematic increases in orthorhombic distortion and unit cell volume at ambient conditions (V0). Compression of the perovskite unit cell is anisotropic, with the a axis about 25% and 3% more compressive than the b and c axes, respectively. The magnitude of orthorhombic distortion increases with pressure, but aluminous perovskite remains stable to at least 100 GPa. Our results show that Al causes only a mild increase in compressibility, with the bulk modulus (K0) decreasing at a rate of 0.7 GPa/0.01 XAl. This increase in compressibility is consistent with recent ab initio calculations if Al mixes into both the 6- and 8-coordinated sites by coupled substitution5, where 2 Al3+ = Mg2+ + Si4+. Our results together with those of [4] indicate that this substitution mechanism predominates throughout the lower mantle. Previous mineralogic models indicating the upper and lower mantle are compositionally similar in terms of major elements remain effectively unchanged because solution of 5 mol% Al into perovskite has a minor effect on density. 1. Zhang & Weidner (1999). Science 284, 782-784. 2. Kubo et al. (2000) Proc. Jap. Acad. 76B, 103-107. 3. Daniel et al

  1. Hydrogen molecule defect in proton-conductive SrTiO3 Perovskite

    Science.gov (United States)

    Onishi, Taku

    2017-11-01

    In proton-conductive SrTiO3 perovskite, no hydrogen molecule defect ideally exists. However, the unforeseen chemical reaction is often observed after the use of fuel cell. From the viewpoint of battery safety, we have investigated the effect of hydrogen molecule defect by molecular orbital analysis. When counter cation vacancy exists, the activation energy for hydrogen molecule migration was 1.39 - 1.50 eV, which is much smaller than the dissociation energy of hydrogen molecule. It implies that hydrogen molecule may migrate without its dissociation.

  2. Highly Emissive Divalent-Ion-Doped Colloidal CsPb1–xMxBr3 Perovskite Nanocrystals through Cation Exchange

    Science.gov (United States)

    2017-01-01

    Colloidal CsPbX3 (X = Br, Cl, and I) perovskite nanocrystals (NCs) have emerged as promising phosphors and solar cell materials due to their remarkable optoelectronic properties. These properties can be tailored by not only controlling the size and shape of the NCs but also postsynthetic composition tuning through topotactic anion exchange. In contrast, property control by cation exchange is still underdeveloped for colloidal CsPbX3 NCs. Here, we present a method that allows partial cation exchange in colloidal CsPbBr3 NCs, whereby Pb2+ is exchanged for several isovalent cations, resulting in doped CsPb1–xMxBr3 NCs (M= Sn2+, Cd2+, and Zn2+; 0 50%), sharp absorption features, and narrow emission of the parent CsPbBr3 NCs. The blue-shift in the optical spectra is attributed to the lattice contraction that accompanies the Pb2+ for M2+ cation exchange and is observed to scale linearly with the lattice contraction. This work opens up new possibilities to engineer the properties of halide perovskite NCs, which to date are demonstrated to be the only known system where cation and anion exchange reactions can be sequentially combined while preserving the original NC shape, resulting in compositionally diverse perovskite NCs. PMID:28260380

  3. Shelf life stability comparison in air for solution processed pristine PDPP3T polymer and doped spiro-OMeTAD as hole transport layer for perovskite solar cell

    Directory of Open Access Journals (Sweden)

    Ashish Dubey

    2016-06-01

    Full Text Available This data in brief includes forward and reverse scanned current density–voltage (J–V characteristics of perovskite solar cells with PDPP3T and spiro-OMeTAD as HTL, stability testing conditions of perovskite solar cell shelf life in air for both PDPP3T and spiro-OMeTAD as HTL as per the description in Ref. [1], and individual J–V performance parameters acquired with increasing time exposed in ambient air are shown for both type of devices using PDPP3T and spiro-OMeTAD as HTL. The data collected in this study compares the device stability with time for both PDPP3T and spiro-OMeTAD based perovskite solar cells and is directly related to our research article “solution processed pristine PDPP3T polymer as hole transport layer for efficient perovskite solar cells with slower degradation” [2].

  4. Synthesis of LaNiO{sub 3} perovskite by the modified proteic gel method and study of catalytic properties in the syngas production

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Jose C.; Mesquita, Maria E.; Pedrosa, Anne M. Garrido, E-mail: annemgp@ufs.br, E-mail: annemgp@yahoo.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Quimica e Engenharia Quimica; Souza, Marcelo J.B. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Engenharia Quimica; Ruiz, Juan A.C. [Centro de Tecnologias do Gas e Energias Renovaveis (CTGAS-ER), Natal, RN (Brazil). Laboratorio de Processamento do Gas; Melo, Dulce M.A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Ciencias Exatas e da Terra. Depaertamento de Quimica

    2012-10-15

    This work describes a study on the synthesis of LaNiO{sub 3} perovskites via the modified proteic gel method, varying collagen content and on the catalytic activity of LaNiO{sub 3} and LaNiO{sub 3}/Al{sub 2}O{sub 3} in the syngas (CO + H{sub 2}) production. X-ray diffraction patterns revealed the formation of perovskite structure in all samples prepared by proteic gel synthesis method, varying collagen content and after calcination at 700 deg C for 2 h. LaNiO{sub 3}/Al{sub 2}O{sub 3} catalyst prepared by the impregnation method showed diffraction peaks due to the perovskite structure and to the support (Al{sub 2}O{sub 3}). This catalyst presented: specific surface of 46.1 m{sup 2} g{sup -1}, two reduction peaks in the temperature programmed reduction (TPR) profile and 46% of methane conversion (by the partial oxidation of methane using oxygen) after 18 h of reaction. (author)

  5. Light-trapping in perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Du, Qing Guo, E-mail: duqi0001@e.ntu.edu.sg [Department of Physics, University of Toronto, 60 ST. George St., Toronto, Ontario, M5S 1A7 (Canada); Institute of High Performance Computing, A* STAR, Singapore, 138632 (Singapore); Shen, Guansheng [Department of Physics, University of Toronto, 60 ST. George St., Toronto, Ontario, M5S 1A7 (Canada); School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); John, Sajeev [Department of Physics, University of Toronto, 60 ST. George St., Toronto, Ontario, M5S 1A7 (Canada); Department of Physics, Soochow University, Suzhou (China)

    2016-06-15

    We numerically demonstrate enhanced light harvesting efficiency in both CH{sub 3}NH{sub 3}PbI{sub 3} and CH(NH{sub 2}){sub 2}PbI{sub 3}-based perovskite solar cells using inverted vertical-cone photonic-crystal nanostructures. For CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cells, the maximum achievable photocurrent density (MAPD) reaches 25.1 mA/cm{sup 2}, corresponding to 92% of the total available photocurrent in the absorption range of 300 nm to 800 nm. Our cell shows 6% absorption enhancement compared to the Lambertian limit (23.7 mA/cm{sup 2}) and has a projected power conversion efficiency of 12.9%. Excellent solar absorption is numerically demonstrated over a broad angular range from 0 to 60 degree for both S- and P- polarizations. For the corresponding CH(NH{sub 2}){sub 2}PbI{sub 3} based perovskite solar cell, with absorption range of 300 nm to 850 nm, we find a MAPD of 29.1 mA/cm{sup 2}, corresponding to 95.4% of the total available photocurrent. The projected power conversion efficiency of the CH(NH{sub 2}){sub 2}PbI{sub 3} based photonic crystal solar cell is 23.4%, well above the current world record efficiency of 20.1%.

  6. A-Site Deficient (Pr0.6Sr0.4)(1-s)Fe0.8Co0.2O3-delta Perovskites as Solid Oxide Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent

    2009-01-01

    Five A-site deficient (Pr0.6Sr0.4)1−sFe0.8Co0.2O3perovskites (s=0.01, 0.05, 0.10, 0.15, and 0.20) were synthesized using the glycine-nitrate process. The perovskites were characterized with powder X-ray diffraction (XRD), dilatometry, four-point dc conductivity measurements, and electrochemical...... resistance more than 3 times lower than the weakly A-site deficient (Pr0.6Sr0.4)0.99Fe0.8Co0.2O3perovskite. ©2009 The Electrochemical Society...

  7. Antisolvent-assisted powder engineering for controlled growth of hybrid CH3NH3PbI3 perovskite thin films

    Directory of Open Access Journals (Sweden)

    Yong Chan Choi

    2017-02-01

    Full Text Available We develop antisolvent-assisted powder engineering for the controlled growth of hybrid inorganic-organic CH3NH3PbI3 (MAPbI3 perovskite thin films. The powders, which are used as the precursors for solution processing, are synthesized by pouring a MAPbI3 precursor solution into various antisolvents, such as dichloromethane, chloroform, diethyl ether, and toluene. Two types of powders having different colors are obtained, depending on the antisolvent used. The choice of the antisolvent used for synthesizing the powders strongly influences not only the phases of the powders but also the morphology and structure of the thin films subsequently fabricated by solution processing. This, in turn, affects the photovoltaic performance.

  8. Viscosity, surface tension, density and contact angle of selected PbI2, PbCl2 and methylammonium lead halide perovskite solutions used in perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza Ahmadian-Yazdi

    2018-02-01

    Full Text Available Perovskite solar cells (PSCs are currently under vigorous research and development, owing to their compelling power conversion efficiencies. PSCs are solution-processed and, therefore, are fabricated using casting and printing methods, such as spin, spray and blade coating. The coating characteristics significantly depend on the physical and rheological properties of the solutions. Thus, due to the scarcity of such properties, in this work, we report the surface tension, viscosity, density, and contact angle of selected methylammonium lead halide perovskite solutions, in order to gain insight into the behavior of the perovskite solutions and the range of such physical properties. The contact angles were measured on PEDOT:PSS and compact TiO2 (c-TiO2 substrates, commonly used as the underneath layers of the perovskite film. In total, 12 solutions of CH3NH3PbI3 and CH3NH3PbI3-xClx dissolved in common solvents, as well as solutions of PbI2, PbCl2, and CH3NH3I were tested. Among the results, it is shown that the tested perovskite solutions are Newtonian, the apparent contact angles on the mesoporous TiO2 (m-TiO2 are close to zero, on the PEDOT:PSS are around 10°, and on the c-TiO2 are around 30°. Also, contact angle hysteresis is observed in the case of the c-TiO2 substrates. Representative impact dynamics and spreading of perovskite solution droplets are also studied, to demonstrate the importance of the solution properties and process parameters on the coating process.

  9. Viscosity, surface tension, density and contact angle of selected PbI2, PbCl2 and methylammonium lead halide perovskite solutions used in perovskite solar cells

    Science.gov (United States)

    Ahmadian-Yazdi, Mohammad-Reza; Rahimzadeh, Amin; Chouqi, Zineb; Miao, Yihe; Eslamian, Morteza

    2018-02-01

    Perovskite solar cells (PSCs) are currently under vigorous research and development, owing to their compelling power conversion efficiencies. PSCs are solution-processed and, therefore, are fabricated using casting and printing methods, such as spin, spray and blade coating. The coating characteristics significantly depend on the physical and rheological properties of the solutions. Thus, due to the scarcity of such properties, in this work, we report the surface tension, viscosity, density, and contact angle of selected methylammonium lead halide perovskite solutions, in order to gain insight into the behavior of the perovskite solutions and the range of such physical properties. The contact angles were measured on PEDOT:PSS and compact TiO2 (c-TiO2) substrates, commonly used as the underneath layers of the perovskite film. In total, 12 solutions of CH3NH3PbI3 and CH3NH3PbI3-xClx dissolved in common solvents, as well as solutions of PbI2, PbCl2, and CH3NH3I were tested. Among the results, it is shown that the tested perovskite solutions are Newtonian, the apparent contact angles on the mesoporous TiO2 (m-TiO2) are close to zero, on the PEDOT:PSS are around 10°, and on the c-TiO2 are around 30°. Also, contact angle hysteresis is observed in the case of the c-TiO2 substrates. Representative impact dynamics and spreading of perovskite solution droplets are also studied, to demonstrate the importance of the solution properties and process parameters on the coating process.

  10. System Ba/sub 2/Gdsub(2/3)vacantsub(1/3)Usub(1-x)Wsub(x)O/sub 6/ and hexagonal perovskites of an 18-layer type

    Energy Technology Data Exchange (ETDEWEB)

    Wischert, W; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1978-04-01

    In the system Ba/sub 2/Gdsub(2/3)vacantsub(1/3)Usub(1-x)Wsub(x)O/sub 6/ the formation of a continuous solid solution series is observed. With x <= 0.9 the mixed crystals have a cubic 1:1 ordered perovskite structure. With x >= 0.95 the compounds are polymorphic: besides an cubic 1:1 ordered perovskite type for x = 0.95; 0.99 and 1.00 one hexagonal layer structure exists. This lattice is in all cases rhombohedral (space group R3m) and represents an 18 L-type. Likewise the compounds Ba/sub 2/Bsub(2/3)sup(III)vacantsub(1/3)Wsup(VI)O/sub 6/ with Bsup(III) Tb-Lu and Y belong to the 18 L-type.

  11. Enhancing Hybrid Perovskite Detectability in the Deep Ultraviolet Region with Down-Conversion Dual-Phase (CsPbBr3-Cs4PbBr6) Films.

    Science.gov (United States)

    Tong, Guoqing; Li, Huan; Zhu, Zhifeng; Zhang, Yan; Yu, Linwei; Xu, Jun; Jiang, Yang

    2018-04-05

    Hybrid perovskite photodetectors (PDs) exhibit outstanding performance in the ultraviolet-visible (UV-vis) spectrum but have poor detectability in the deep ultraviolet (DUV) region (200-350 nm). In this work, a novel inorganic-hybrid architecture that incorporates a dual-phase (CsPbBr 3 -Cs 4 PbBr 6 ) inorganic perovskite material as a down-conversion window layer and a hybrid perovskite as a light capture layer was prepared to achieve faster, highly sensitive photodetection in the DUV spectrum. A dual-phase inorganic perovskite film coated on the back surface of the photodetector enables strong light absorption and tunes the incident energy into emission bands that are optimized for the perovskite photodetector. The presence of Cs 4 PbBr 6 enhances the capture and down-conversion of the incident DUV light. Due to the down-conversion and transport of the DUV photons, a self-driven perovskite photodetector with this composite structure exhibits a fast response time of 7.8/33.6 μs and a high responsivity of 49.4 mA W -1 at 254 nm without extra power supply.

  12. Solution-Phase Synthesis of Cesium Lead Halide Perovskite Nanowires.

    Science.gov (United States)

    Zhang, Dandan; Eaton, Samuel W; Yu, Yi; Dou, Letian; Yang, Peidong

    2015-07-29

    Halide perovskites have attracted much attention over the past 5 years as a promising class of materials for optoelectronic applications. However, compared to hybrid organic-inorganic perovskites, the study of their pure inorganic counterparts, like cesium lead halides (CsPbX3), lags far behind. Here, a catalyst-free, solution-phase synthesis of CsPbX3 nanowires (NWs) is reported. These NWs are single-crystalline, with uniform growth direction, and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites.

  13. Quantum Dots in Two-Dimensional Perovskite Matrices for Efficient Near-Infrared Light Emission

    KAUST Repository

    Yang, Zhenyu

    2017-03-13

    Quantum-dot-in-perovskite solids are excellent candidates for infrared light-emitting applications. The first generation of dot-in-perovskite light-emitting diodes (LEDs) has shown bright infrared electroluminescence with tunable emission wavelength; however, their performance has been limited by degradation of the active layer at practical operating voltages. This arises from the instability of the three-dimensional (3D) organolead halide perovskite matrix. Herein we report the first dot-in-perovskite solids that employ two-dimensional (2D) perovskites as the matrix. 2D perovskite passivation is achieved via an in situ alkylammonium/alkylamine substitution carried out during the quantum dot (QD) ligand exchange process. This single-step film preparation process enables deposition of the QD/perovskite active layers with thicknesses of 40 nm, over seven times thinner than the first-generation dot-in-perovskite thin films that relied on a multistep synthesis. The dot-in-perovskite film roughness improved from 31 nm for the first-generation films to 3 nm for films as a result of this new approach. The best devices exhibit external quantum efficiency peaks exceeding 2% and radiances of ∼1 W sr–1 m–2, with an improved breakdown voltage up to 7.5 V. Compared to first-generation dot-in-perovskites, this new process reduces materials consumptions 10-fold and represents a promising step toward manufacturable devices.

  14. Quantum Dots in Two-Dimensional Perovskite Matrices for Efficient Near-Infrared Light Emission

    KAUST Repository

    Yang, Zhenyu; Voznyy, Oleksandr; Walters, Grant; Fan, James Z.; Liu, Min; Kinge, Sachin; Hoogland, Sjoerd; Sargent, Edward H.

    2017-01-01

    Quantum-dot-in-perovskite solids are excellent candidates for infrared light-emitting applications. The first generation of dot-in-perovskite light-emitting diodes (LEDs) has shown bright infrared electroluminescence with tunable emission wavelength; however, their performance has been limited by degradation of the active layer at practical operating voltages. This arises from the instability of the three-dimensional (3D) organolead halide perovskite matrix. Herein we report the first dot-in-perovskite solids that employ two-dimensional (2D) perovskites as the matrix. 2D perovskite passivation is achieved via an in situ alkylammonium/alkylamine substitution carried out during the quantum dot (QD) ligand exchange process. This single-step film preparation process enables deposition of the QD/perovskite active layers with thicknesses of 40 nm, over seven times thinner than the first-generation dot-in-perovskite thin films that relied on a multistep synthesis. The dot-in-perovskite film roughness improved from 31 nm for the first-generation films to 3 nm for films as a result of this new approach. The best devices exhibit external quantum efficiency peaks exceeding 2% and radiances of ∼1 W sr–1 m–2, with an improved breakdown voltage up to 7.5 V. Compared to first-generation dot-in-perovskites, this new process reduces materials consumptions 10-fold and represents a promising step toward manufacturable devices.

  15. Enhanced Power Conversion Efficiency of Perovskite Solar Cells with an Up-Conversion Material of Er3+-Yb3+-Li+ Tri-doped TiO2.

    Science.gov (United States)

    Zhang, Zhenlong; Qin, Jianqiang; Shi, Wenjia; Liu, Yanyan; Zhang, Yan; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

    2018-05-11

    In this paper, Er 3+ -Yb 3+ -Li + tri-doped TiO 2 (UC-TiO 2 ) was prepared by an addition of Li + to Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 presented an enhanced up-conversion emission compared with Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 was applied to the perovskite solar cells. The power conversion efficiency (PCE) of the solar cells without UC-TiO 2 was 14.0%, while the PCE of the solar cells with UC-TiO 2 was increased to 16.5%, which presented an increase of 19%. The results suggested that UC-TiO 2 is an effective up-conversion material. And this study provided a route to expand the spectral absorption of perovskite solar cells from visible light to near-infrared using up-conversion materials.

  16. Stable Graphene-Two-Dimensional Multiphase Perovskite Heterostructure Phototransistors with High Gain.

    Science.gov (United States)

    Shao, Yuchuan; Liu, Ye; Chen, Xiaolong; Chen, Chen; Sarpkaya, Ibrahim; Chen, Zhaolai; Fang, Yanjun; Kong, Jaemin; Watanabe, Kenji; Taniguchi, Takashi; Taylor, André; Huang, Jinsong; Xia, Fengnian

    2017-12-13

    Recently, two-dimensional (2D) organic-inorganic perovskites emerged as an alternative material for their three-dimensional (3D) counterparts in photovoltaic applications with improved moisture resistance. Here, we report a stable, high-gain phototransistor consisting of a monolayer graphene on hexagonal boron nitride (hBN) covered by a 2D multiphase perovskite heterostructure, which was realized using a newly developed two-step ligand exchange method. In this phototransistor, the multiple phases with varying bandgap in 2D perovskite thin films are aligned for the efficient electron-hole pair separation, leading to a high responsivity of ∼10 5 A W -1 at 532 nm. Moreover, the designed phase alignment method aggregates more hydrophobic butylammonium cations close to the upper surface of the 2D perovskite thin film, preventing the permeation of moisture and enhancing the device stability dramatically. In addition, faster photoresponse and smaller 1/f noise observed in the 2D perovskite phototransistors indicate a smaller density of deep hole traps in the 2D perovskite thin film compared with their 3D counterparts. These desirable properties not only improve the performance of the phototransistor, but also provide a new direction for the future enhancement of the efficiency of 2D perovskite photovoltaics.

  17. Additive to regulate the perovskite crystal film growth in planar heterojunction solar cells

    International Nuclear Information System (INIS)

    Song, Xin; Sun, Po; Chen, Zhi-Kuan; Wang, Weiwei; Ma, Wanli

    2015-01-01

    We reported a planar heterojunction perovskite solar cell fabricated from MAPbI 3−x Cl x perovskite precursor solution containing 1-chloronaphthalene (CN) additive. The MAPbI 3−x Cl x perovskite films have been characterized by UV-vis, SEM, XRD, and steady-state photoluminescence (PL). UV-vis absorption spectra measurement shows that the absorbance of the film with CN additive is significantly higher than the pristine film and the absorption peak is red shift by 30 nm, indicating the perovskite film with additive possessing better crystal structures. In-situ XRD study of the perovskite films with additive demonstrated intense diffraction peaks from MAPbI 3−x Cl x perovskite crystal planes of (110), (220), and (330). SEM images of the films with additive indicated the films were more smooth and homogenous with fewer pin-holes and voids and better surface coverage than the pristine films. These results implied that the additive CN is beneficial to regulate the crystallization transformation kinetics of perovskite to form high quality crystal films. The steady-state PL measurement suggested that the films with additive contained less charge traps and defects. The planar heterojunction perovskite solar cells fabricated from perovskite precursor solution containing CN additive demonstrated 30% enhancement in performance compared to the devices with pristine films. The improvement in device efficiency is mainly attributed to the good crystal structures, more homogenous film morphology, and also fewer trap centers and defects in the films with the additive

  18. Perovskite solar cells for roll-to-roll fabrication

    Directory of Open Access Journals (Sweden)

    Uddin Ashraf

    2017-01-01

    Full Text Available Perovskite solar cell (PSCs is considered as the game changer in emerging photovoltaics technology. The highest certified efficiency is 22% with high temperature processed (∼500 °C TiO2 based electron transport layer (ETL. High temperature process is a rudimentary hindrance towards roll-to-roll processing of PSCs on flexible substrates. Low temperature solution process (<150 °C ZnO based ETL is one of the most promising candidate for large scale roll-to-roll fabrication of cells as it has nearly identical electron affinity (4.2 eV of TiO2. The mixed organic perovskite (MA0.6FA0.4PbI3 devices with Al doped ZnO (AZO ETL demonstrate average cell efficiency over 16%, which is the highest ever reported efficiency for this device configuration. The energy level alignment and related interfacial charge transport dynamics at the interface of ZnO and perovskite films and the adjacent charge transport layers are investigated. Significantly improved device stability, hysteresis free device photocurrent have been observed in MA0.6FA0.4PbI3 cells. A systematic electrochemical impedance spectroscopy, frequency dependent capacitance spectra, surface morphology and topography characterization have been conducted to understand the role of interfacial electronic properties between perovskite and neighbouring layers in perovskite device. A standardized degradation study, interfacial electronic property and capacitive spectra analysis of aged device, have been measured to understand the enhanced device stability in mixed MA0.6FA0.4PbI3 cells. Slow perovskite material decomposition rate and augmented device lifetime with AZO based devices have been found to be correlated with the more hydrophobic and acidic nature of AZO surface compared to pristine ZnO film.

  19. Inkjet printable-photoactive all inorganic perovskite films with long effective photocarrier lifetimes

    Science.gov (United States)

    Ilie, C. C.; Guzman, F.; Swanson, B. L.; Evans, I. R.; Costa, P. S.; Teeter, J. D.; Shekhirev, M.; Benker, N.; Sikich, S.; Enders, A.; Dowben, P. A.; Sinitskii, A.; Yost, A. J.

    2018-05-01

    Photoactive perovskite quantum dot films, deposited via an inkjet printer, have been characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The crystal structure and bonding environment are consistent with CsPbBr3 perovskite quantum dots. The current–voltage (I–V) and capacitance–voltage (C–V) transport measurements indicate that the photo-carrier drift lifetime can exceed 1 ms for some printed perovskite films. This far exceeds the dark drift carrier lifetime, which is below 50 ns. The printed films show a photocarrier density 109 greater than the dark carrier density, making these printed films ideal candidates for application in photodetectors. The successful printing of photoactive-perovskite quantum dot films of CsPbBr3, indicates that the rapid prototyping of various perovskite inks and multilayers is realizable.

  20. Adsorption of molecular additive onto lead halide perovskite surfaces: A computational study on Lewis base thiophene additive passivation

    Science.gov (United States)

    Zhang, Lei; Yu, Fengxi; Chen, Lihong; Li, Jingfa

    2018-06-01

    Organic additives, such as the Lewis base thiophene, have been successfully applied to passivate halide perovskite surfaces, improving the stability and properties of perovskite devices based on CH3NH3PbI3. Yet, the detailed nanostructure of the perovskite surface passivated by additives and the mechanisms of such passivation are not well understood. This study presents a nanoscopic view on the interfacial structure of an additive/perovskite interface, consisting of a Lewis base thiophene molecular additive and a lead halide perovskite surface substrate, providing insights on the mechanisms that molecular additives can passivate the halide perovskite surfaces and enhance the perovskite-based device performance. Molecular dynamics study on the interactions between water molecules and the perovskite surfaces passivated by the investigated additive reveal the effectiveness of employing the molecular additives to improve the stability of the halide perovskite materials. The additive/perovskite surface system is further probed via molecular engineering the perovskite surfaces. This study reveals the nanoscopic structure-property relationships of the halide perovskite surface passivated by molecular additives, which helps the fundamental understanding of the surface/interface engineering strategies for the development of halide perovskite based devices.

  1. Effect of Non-Stoichiometric Solution Chemistry on Improving the Performance of Wide-Bandgap Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Kai [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yang, Mengjin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kim, Donghoe [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Li, Zhen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Reid, Obadiah G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yue [University of Toledo; Song, Zhaoning [University of Toledo; Zhao, Dewei [University of Toledo; Wang, Changlei [University of Toledo; Li, Liwei [ENN Energy Research Institute; ENN Solar Energy Co., Ltd.; Meng, Yuan [ENN Energy Research Institute; ENN Solar Energy Co., Ltd.; Guo, Ted [ENN Energy Research Institute; ENN Solar Energy Co., Ltd.; Yan, Yanfa [University of Toledo

    2017-10-18

    A high-efficiency wide-bandgap (WBG) perovskite solar cell is critical for developing perovskite-related (e.g., all-perovskite, perovskite/Si, or perovskite/Cu(In,Ga)Se2) tandem devices. Here, we demonstrate the use of non-stoichiometric precursor chemistry with excess methylammonium halides (MAX; X = I, Br, or Cl) for preparing high-quality ~1.75-eV FA0.83Cs0.17Pb(I0.6Br0.4)3 perovskite solar cells. Among various methylammonium halides, using excess MABr in the non-stoichiometric precursor exhibits the strongest effect on improving perovskite crystallographic properties and device characteristics without affecting the perovskite composition. In contrast, using excess MAI significantly reduces the bandgap of perovskite due to the replacement of Br with I. Using 40% excess MABr, we demonstrate a single-junction WBG perovskite solar cell with stabilized efficiency of 16.4%. We further demonstrate a 20.3%-efficient 4-terminal tandem device by using a 14.7%-efficient semi-transparent WBG perovskite top cell and an 18.6%-efficient unfiltered (5.6%-efficient filtered) Si bottom cell.

  2. Stable perovskite solar cells by surface modification with surfactant molecules

    Energy Technology Data Exchange (ETDEWEB)

    Holanda, Matheus Serra de; Nogueira, Ana Flavia, E-mail: mholandabsb@outlook.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica

    2016-07-01

    Full text: Surface modification on organic-inorganic perovskite films using dodecylammonium chloride was done to improve the stability of the material over the air moisture, which is considered extremely harmful to these materials and complicates their application on solar cell technology. Perovskite CH{sub 3}NH{sub 3}PbI{sub 3} was prepared by single step method using a solution containing PbI{sub 2} and CH{sub 3}NH{sub 3}I on DMF:DMSO (2:1) on a concentration of 0.88 mol L{sup -1}. The film was deposited over a planar film of TiO{sub 2}, previously deposited over FTO glass, by using spin-casting method. 25 μL of the solution was spread over the substrate which was turned at 4000 RPM for 45 s. In the last 10 s, 800 μL of monochlorobenzene was dropped. The film was submitted to a thermal treatment so the conversion of the perovskite could be completed. After the thermal treatment, the modifier was spin coated over the perovskite film from 5 and 10 mg mL{sup -1} solutions of the dodecylammonium chloride in chloroform. The perovskite films were characterized by SEM, XRD and UV-Vis spectroscopy. SEM images have shown that the modifiers agglomerate and they cover the perovskite film, forming a protection layer. XRD and UV-Vis carried out after the film preparation, 7 and 15 days after the deposition. The first results show that the protection layer is able to avoid degradation of the perovskite film. Photovoltaic devices were prepared by depositing Spiro-OMeTAD as HTM layer and gold as electrode. It was observed that the increase on the thickness of the surfactant layer causes a decrease on the short-circuit current density (JSC), which is expected since is starts to act like an insulating layer. This effect is also the cause of the reduction of the fill factor (FF). More experiments need to be carried out to improve the solar cells devices, but the present data has shown the potential of the method developed, which uses easy access surfactants and a simple

  3. Stable perovskite solar cells by surface modification with surfactant molecules

    International Nuclear Information System (INIS)

    Holanda, Matheus Serra de; Nogueira, Ana Flavia

    2016-01-01

    Full text: Surface modification on organic-inorganic perovskite films using dodecylammonium chloride was done to improve the stability of the material over the air moisture, which is considered extremely harmful to these materials and complicates their application on solar cell technology. Perovskite CH 3 NH 3 PbI 3 was prepared by single step method using a solution containing PbI 2 and CH 3 NH 3 I on DMF:DMSO (2:1) on a concentration of 0.88 mol L -1 . The film was deposited over a planar film of TiO 2 , previously deposited over FTO glass, by using spin-casting method. 25 μL of the solution was spread over the substrate which was turned at 4000 RPM for 45 s. In the last 10 s, 800 μL of monochlorobenzene was dropped. The film was submitted to a thermal treatment so the conversion of the perovskite could be completed. After the thermal treatment, the modifier was spin coated over the perovskite film from 5 and 10 mg mL -1 solutions of the dodecylammonium chloride in chloroform. The perovskite films were characterized by SEM, XRD and UV-Vis spectroscopy. SEM images have shown that the modifiers agglomerate and they cover the perovskite film, forming a protection layer. XRD and UV-Vis carried out after the film preparation, 7 and 15 days after the deposition. The first results show that the protection layer is able to avoid degradation of the perovskite film. Photovoltaic devices were prepared by depositing Spiro-OMeTAD as HTM layer and gold as electrode. It was observed that the increase on the thickness of the surfactant layer causes a decrease on the short-circuit current density (JSC), which is expected since is starts to act like an insulating layer. This effect is also the cause of the reduction of the fill factor (FF). More experiments need to be carried out to improve the solar cells devices, but the present data has shown the potential of the method developed, which uses easy access surfactants and a simple preparation method to improve the stability of

  4. Junction Propagation in Organometal Halide Perovskite-Polymer Composite Thin Films.

    Science.gov (United States)

    Shan, Xin; Li, Junqiang; Chen, Mingming; Geske, Thomas; Bade, Sri Ganesh R; Yu, Zhibin

    2017-06-01

    With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p-i-n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr 3 )/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation.

  5. Perovskite semiconductor La(Ni{sub 0.75}W{sub 0.25})O{sub 3} nanoparticles for visible-light-absorbing photocatalytic material

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Xie, Hongde, E-mail: xiehongde@suda.edu.cn; Pu, Yinfu; Huang, Yanlin [Soochow University, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science (China); Qin, Lin; Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Pukyong National University, Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering (Korea, Republic of)

    2017-01-15

    La(Ni{sub 0.75}W{sub 0.25})O{sub 3} perovskite oxide was prepared via the sol–gel Pechini route. The pure crystalline phase was verified via X-ray diffraction measurements and Rietveld structure refinements. Some measurements were applied to characterize the surface of the nanoparticles such as transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, specific surface area, and X-ray photo-electron spectroscopy measurements. The optical measurement confirmed that this perovskite oxide can absorb the visible light presenting low band energy of 2.41 eV. The d–d allowed transitions in Ni{sup 2+}-O octahedral have great contributions to the narrow band-gap. The Ni{sup 2+}-containing perovskite was applied as a photocatalyst showing the desirable photodegradation ability for methylene blue solutions under the excitation of visible-light. The photocatalysis activities were discussed in the relationship with its special perovskite-type structure such as the NiO{sub 6} color centers and multivalent cation ions etc.

  6. Rational Strategies for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Seo, Jangwon; Noh, Jun Hong; Seok, Sang Il

    2016-03-15

    A long-standing dream in the large scale application of solar energy conversion is the fabrication of solar cells with high-efficiency and long-term stability at low cost. The realization of such practical goals depends on the architecture, process and key materials because solar cells are typically constructed from multilayer heterostructures of light harvesters, with electron and hole transporting layers as a major component. Recently, inorganic-organic hybrid lead halide perovskites have attracted significant attention as light absorbers for the fabrication of low-cost and high-efficiency solar cells via a solution process. This mainly stems from long-range ambipolar charge transport properties, low exciton binding energies, and suitable band gap tuning by managing the chemical composition. In our pioneering work, a new photovoltaic platform for efficient perovskite solar cells (PSCs) was proposed, which yielded a high power conversion efficiency (PCE) of 12%. The platform consisted of a pillared architecture of a three-dimensional nanocomposite of perovskites fully infiltrating mesoporous TiO2, resulting in the formation of continuous phases and perovskite domains overlaid with a polymeric hole conductor. Since then, the PCE of our PSCs has been rapidly increased from 3% to over 20% certified efficiency. The unprecedented increase in the PCE can be attributed to the effective integration of the advantageous attributes of the refined bicontinuous architecture, deposition process, and composition of perovskite materials. Specifically, the bicontinuous architectures used in the high efficiency comprise a layer of perovskite sandwiched between mesoporous metal-oxide layer, which is a very thinner than that of used in conventional dye-sensitized solar cells, and hole-conducting contact materials with a metal back contact. The mesoporous scaffold can affect the hysteresis under different scan direction in measurements of PSCs. The hysteresis also greatly depends on

  7. Modulating Excitonic Recombination Effects through One-Step Synthesis of Perovskite Nanoparticles for Light-Emitting Diodes.

    Science.gov (United States)

    Kulkarni, Sneha A; Muduli, Subas; Xing, Guichuan; Yantara, Natalia; Li, Mingjie; Chen, Shi; Sum, Tze Chien; Mathews, Nripan; White, Tim J; Mhaisalkar, Subodh G

    2017-10-09

    The primary advantages of halide perovskites for light-emitting diodes (LEDs) are solution processability, direct band gap, good charge-carrier diffusion lengths, low trap density, and reasonable carrier mobility. The luminescence in 3 D halide perovskite thin films originates from free electron-hole bimolecular recombination. However, the slow bimolecular recombination rate is a fundamental performance limitation. Perovskite nanoparticles could result in improved performance but processability and cumbersome synthetic procedures remain challenges. Herein, these constraints are overcome by tailoring the 3 D perovskite as a near monodisperse nanoparticle film prepared through a one-step in situ deposition method. Replacing methyl ammonium bromide (CH 3 NH 3 Br, MABr) partially by octyl ammonium bromide [CH 3 (CH 2 ) 7 NH 3 Br, OABr] in defined mole ratios in the perovskite precursor proved crucial for the nanoparticle formation. Films consisting of the in situ formed nanoparticles displayed signatures associated with excitonic recombination, rather than that of bimolecular recombination associated with 3 D perovskites. This transition was accompanied by enhanced photoluminescence quantum yield (PLQY≈20.5 % vs. 3.40 %). Perovskite LEDs fabricated from the nanoparticle films exhibit a one order of magnitude improvement in current efficiency and doubling in luminance efficiency. The material processing systematics derived from this study provides the means to control perovskite morphologies through the selection and mixing of appropriate additives. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis of Phase Pure Hexagonal YFeO3 Perovskite as Efficient Visible Light Active Photocatalyst

    Directory of Open Access Journals (Sweden)

    Mohammed Ismael

    2017-11-01

    Full Text Available Hexagonal perovskite YFeO3 was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS and Tauc plots, the hexagonal YFeO3 exhibits a lower optical band gap (1.81 eV than the orthorhombic structure (about 2.1 eV or even higher being typically obtained at elevated temperatures (>700 °C, and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO3 perovskites were analyzed by powder X-ray diffraction (XRD and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO3 with a hexagonal phase. The photocatalytic activity of the different YFeO3 phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO3 and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y2O3 might support the photocatalysis by improving the separation of photogenerated charge carriers.

  9. The Role of Surface Tension in the Crystallization of Metal Halide Perovskites

    KAUST Repository

    Zhumekenov, Ayan A.

    2017-07-06

    The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current bottlenecks retarding the shift towards single crystal-based optoelectronics. Here we theoretically and experimentally elucidate the role of surface tension in the rapid synthesis of perovskite single crystals by inverse temperature crystallization (ITC). Understanding the nucleation and growth mechanisms enabled us to exploit surface tension to direct the growth of monocrystalline films of perovskites (AMX3, where A = CH3NH3+ or MA; M = Pb2+, Sn2+; X = Br-, I-) on the solution surface. We achieve up to 1 cm2-sized monocrystalline films with thickness on the order of the charge carrier diffusion length (~5-10 µm). Our work paves the way to control the crystallization process of perovskites, including thin film deposition, which is essential to advance the performance benchmarks of perovskite optoelectronics.

  10. Visual and sensitive fluorescent sensing for ultratrace mercury ions by perovskite quantum dots.

    Science.gov (United States)

    Lu, Li-Qiang; Tan, Tian; Tian, Xi-Ke; Li, Yong; Deng, Pan

    2017-09-15

    Mercury ions sensing is an important issue for human health and environmental safety. A novel fluorescence nanosensor was designed for rapid visual detection of ultratrace mercury ions (Hg 2+ ) by using CH 3 NH 3 PbBr 3 perovskite quantum dots (QDs) based on the surface ion-exchange mechanism. The synthesized CH 3 NH 3 PbBr 3 QDs can emitt intense green fluorescence with high quantum yield of 50.28%, and can be applied for Hg 2+ sensing with the detection limit of 0.124 nM (24.87 ppt) in the range of 0 nM-100 nM. Furthermore, the interfering metal ions have no any influence on the fluorescence intensity of QDs, showing the perovskite QDs possess the high selectivity and sensitivity for Hg 2+ detection. The sensing mechanism of perovskite QDs for Hg 2+ is has also been investigated by XPS, EDX studies, showing Pb 2+ on the surface of perovskite QDs has been partially replaced by Hg 2+ . Spot plate test shows that the perovskite QDs can also be used for visual detection of Hg 2+ . Our research indicated the perovskite QDs are promising candidates for the visual fluorescence detection of environmental micropollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. One-Step Printable Perovskite Films Fabricated under Ambient Conditions for Efficient and Reproducible Solar Cells.

    Science.gov (United States)

    Jung, Yen-Sook; Hwang, Kyeongil; Heo, Youn-Jung; Kim, Jueng-Eun; Lee, Donmin; Lee, Cheol-Ho; Joh, Han-Ik; Yeo, Jun-Seok; Kim, Dong-Yu

    2017-08-23

    Despite the potential of roll-to-roll processing for the fabrication of perovskite films, the realization of highly efficient and reproducible perovskite solar cells (PeSCs) through continuous coating techniques and low-temperature processing is still challenging. Here, we demonstrate that efficient and reliable CH 3 NH 3 PbI 3 (MAPbI 3 ) films fabricated by a printing process can be achieved through synergetic effects of binary processing additives, N-cyclohexyl-2-pyrrolidone (CHP) and dimethyl sulfoxide (DMSO). Notably, these perovskite films are deposited from premixed perovskite solutions for facile one-step processing under a room-temperature and ambient atmosphere. The CHP molecules result in the uniform and homogeneous perovskite films even in the one-step slot-die system, which originate from the high boiling point and low vapor pressure of CHP. Meanwhile, the DMSO molecules facilitate the growth of perovskite grains by forming intermediate states with the perovskite precursor molecules. Consequently, fully printed PeSC based on the binary additive system exhibits a high PCE of 12.56% with a high reproducibility.

  12. Low-Dimensional-Networked Metal Halide Perovskites: The Next Big Thing

    KAUST Repository

    Saidaminov, Makhsud I.

    2017-03-03

    Low-dimensional-networked (low-DN) perovskite derivatives are bulk quantum materials in which charge carriers are localized within ordered metal halide sheets, rods, or clusters that are separated by cationic lattices. After two decades of hibernation, this class of semiconductors reemerged in the past two years, largely catalyzed by the interest in alternative, more stable absorbers to CH3NH3PbI3-type perovskites in photovoltaics. Whether low-DN perovskites will surpass other photovoltaic technologies remains to be seen, but their impressively high photo- and electroluminescence yields have already set new benchmarks in light emission applications. Here we offer our perspective on the most exciting advances in materials design of low-DN perovskites for energy- and optoelectronic-related applications. The next few years will usher in an explosive growth in this tribe of quantum materials, as only a few members have been synthesized, while the potential library of compositions and structures is believed to be much larger and is yet to be discovered.

  13. A New Generation of Luminescent Materials Based on Low-Dimensional Perovskites

    KAUST Repository

    Pan, Jun

    2017-06-02

    Low-dimensional perovskites with high luminescence properties are promising materials for optoelectronic applications. In this article, properties of two emerging types of low-dimensional perovskites are discussed, including perovskite quantum dots CsPbX3 (X = Cl, Br or I) and zero-dimensional perovskite Cs4PbBr6. Moreover, their application for light down conversion in LCD backlighting systems and in visible light communication are also presented. With their superior optical properties, we believe that further development of these materials will potentially open more prospective applications, especially for optoelectronics devices.

  14. Oxide perovskites with tetravalent dysprosium and compounds of the type Ba/sub 3/RE/sub 4/O/sub 9/ (RE = Rare Earth Element)

    Energy Technology Data Exchange (ETDEWEB)

    Brauer, G; Kristen, H [Freiburg Univ. (Germany, F.R.)

    1980-03-01

    In analogy to our investigations concerning tetravalent Nd in oxide perovskites, we also tried to stabilize dysprosium(IV) by incorporation in host-lattices with the perovskite structure. As host-lattices we used BaCeO/sub 3/, BaTbO/sub 3/, and SrTbO/sub 3/. Only in Ba(Ce, Dy)O/sub 3/ we could trace Dy(IV) with certainty. Among the prepared mixed oxides, also the phase Ba/sub 3/Dy/sub 4/O/sub 9/ occured. The lattice parameters of several phases of this latter type were redetermined.

  15. Topotactic phase transformation of the brownmillerite SrCoO2.5 to the perovskite SrCoO3- δ.

    Science.gov (United States)

    Jeen, H; Choi, W S; Freeland, J W; Ohta, H; Jung, C U; Lee, H N

    2013-07-19

    Pulsed laser epitaxy of brownmillerite SrCoO2.5 thin films and their phase transformation to the perovskite SrCoO3-δ are investigated. While the direct growth of the fully oxidized perovskite films is found to be an arduous task, filling some of oxygen vacancies into SrCoO2.5 by topotactic oxidation accompanies systematic evolution of electronic, magnetic, and thermoelectric properties, useful for many information and energy technologies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Chlorine-Incorporation-Induced Formation of the Layered Phase for Antimony-Based Lead-Free Perovskite Solar Cells.

    Science.gov (United States)

    Jiang, Fangyuan; Yang, Dongwen; Jiang, Youyu; Liu, Tiefeng; Zhao, Xingang; Ming, Yue; Luo, Bangwu; Qin, Fei; Fan, Jiacheng; Han, Hongwei; Zhang, Lijun; Zhou, Yinhua

    2018-01-24

    The environmental toxicity of Pb in organic-inorganic hybrid perovskite solar cells remains an issue, which has triggered intense research on seeking alternative Pb-free perovskites for solar applications. Halide perovskites based on group-VA cations of Bi 3+ and Sb 3+ with the same lone-pair ns 2 state as Pb 2+ are promising candidates. Herein, through a joint experimental and theoretical study, we demonstrate that Cl-incorporated methylammonium Sb halide perovskites (CH 3 NH 3 ) 3 Sb 2 Cl X I 9-X show promise as efficient solar absorbers for Pb-free perovskite solar cells. Inclusion of methylammonium chloride into the precursor solutions suppresses the formation of the undesired zero-dimensional dimer phase and leads to the successful synthesis of high-quality perovskite films composed of the two-dimensional layered phase favored for photovoltaics. Solar cells based on the as-obtained (CH 3 NH 3 ) 3 Sb 2 Cl X I 9-X films reach a record-high power conversion efficiency over 2%. This finding offers a new perspective for the development of nontoxic and low-cost Sb-based perovskite solar cells.

  17. Perovskite Solar Cells—Towards Commercialization

    International Nuclear Information System (INIS)

    Ono, Luis K.; Park, Nam-Gyu; Zhu, Kai; Huang, Wei; Qi, Yabing

    2017-01-01

    The Symposium ES1, Perovskite Solar Cells - Towards Commercialization, held at the 2017 Materials Research Society (MRS) Spring Meeting in Phoenix, Arizona (April 17-21, 2017) received ~200 abstracts. The 23 invited talks and 72 contributed oral presentations as well as 3 poster presentation sessions were organized into 13 principal themes according to the contents of the received abstracts. This Energy Focus article provides a concise summary of the opinions from the scientists and engineers who participated in this symposium regarding the recent progresses, challenges, and future directions for perovskite solar cells as well as other optoelectronic devices.

  18. BaZrO3 perovskite nanoparticles as emissive material for organic/inorganic hybrid light-emitting diodes

    DEFF Research Database (Denmark)

    Tamulevičius, S.; Ivaniuk, K.; Cherpak, V.

    2017-01-01

    In the present work we have demonstrated double-channel emission from organic exciplexes coupled to inorganic nanoparticles. The process is demonstrated by yellow-green emission in light-emitting diodes based on organic exciplexes hybridized with perovskite-type dispersed BaZrO3 nanoparticles...

  19. Three-dimensional oriented attachment growth of single-crystal pre-perovskite PbTiO3 hollowed fibers

    KAUST Repository

    Zhao, Ruoyu; Li, Ming; Ren, Zhaohui; Zhu, Yihan; Han, Gaorong

    2017-01-01

    Hollowed single-crystal pre-perovskite PbTiO fibers (PP-PTF) were successfully synthesized via a polyvinyl alcohol (PVA) assisted hydrothermal process. The as-prepared PP-PTF were characterized to be 0.3-1 μm in diameter and tens of micrometers

  20. Interfacial Interactions in Monolayer and Few-Layer SnS/CH3 NH3 PbI3 Perovskite van der Waals Heterostructures and Their Effects on Electronic and Optical Properties.

    Science.gov (United States)

    Li, Jian-Cai; Wei, Zeng-Xi; Huang, Wei-Qing; Ma, Li-Li; Hu, Wangyu; Peng, Ping; Huang, Gui-Fang

    2018-02-05

    A high light-absorption coefficient and long-range hot-carrier transport of hybrid organic-inorganic perovskites give huge potential to their composites in solar energy conversion and environmental protection. Understanding interfacial interactions and their effects are paramount for designing perovskite-based heterostructures with desirable properties. Herein, we systematically investigated the interfacial interactions in monolayer and few-layer SnS/CH 3 NH 3 PbI 3 heterostructures and their effects on the electronic and optical properties of these structures by density functional theory. It was found that the interfacial interactions in SnS/CH 3 NH 3 PbI 3 heterostructures were van der Waals (vdW) interactions, and they were found to be insensitive to the layer number of 2D SnS sheets. Interestingly, although their band gap decreased upon increasing the layer number of SnS, the near-gap electronic states and optical absorption spectra of these heterostructures were found to be strikingly similar. This feature was determined to be critical for the design of 2D layered SnS-based heterostructures. Strong absorption in the ultraviolet and visible-light regions, type II staggered band alignment at the interface, and few-layer SnS as an active co-catalyst make 2D SnS/CH 3 NH 3 PbI 3 heterostructures promising candidates for photocatalysis, photodetectors, and solar energy harvesting and conversion. These results provide first insight into the nature of interfacial interactions and are useful for designing hybrid organic-inorganic perovskite-based devices with novel properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Perovskite-based solar cells with inorganic inverted hybrid planar heterojunction structure

    Directory of Open Access Journals (Sweden)

    Wei-Chih Lai

    2018-01-01

    Full Text Available We demonstrated the good performance of inorganic inverted CH3NH3PbI3 perovskite-based solar cells (SCs with glass/ITO/NiOx/CH3NH3PbI3 perovskite/C60/ room temperature (RT-sputtered ZnO/Al structure. We adopted spin coating and RT sputtering for the deposition of NiOx and ZnO, respectively. The inorganic hole and electron transport layer of NiOx and RT-sputtered ZnO, respectively, could improve the open-circuit voltage (VOC, short-circuit current density (JSC, and power conversion efficiency (η% of the SCs. We obtained inorganic inverted CH3NH3PbI3 perovskite-based SCs with a JSC of 21.96 A/cm2, a VOC of 1.02 V, a fill factor (FF% of 68.2%, and an η% of 15.3% despite the sputtering damage of the RT-sputtered ZnO deposition. Moreover, the RT-sputtered ZnO could function as a diffusion barrier for Al, moisture, and O2. The inorganic inverted CH3NH3PbI3 perovskite-based SCs demonstrated improved storage reliability.

  2. Perovskite-based solar cells with inorganic inverted hybrid planar heterojunction structure

    Science.gov (United States)

    Lai, Wei-Chih; Lin, Kun-Wei; Guo, Tzung-Fang; Chen, Peter; Liao, Yuan-Yu

    2018-01-01

    We demonstrated the good performance of inorganic inverted CH3NH3PbI3 perovskite-based solar cells (SCs) with glass/ITO/NiOx/CH3NH3PbI3 perovskite/C60/ room temperature (RT)-sputtered ZnO/Al structure. We adopted spin coating and RT sputtering for the deposition of NiOx and ZnO, respectively. The inorganic hole and electron transport layer of NiOx and RT-sputtered ZnO, respectively, could improve the open-circuit voltage (VOC), short-circuit current density (JSC), and power conversion efficiency (η%) of the SCs. We obtained inorganic inverted CH3NH3PbI3 perovskite-based SCs with a JSC of 21.96 A/cm2, a VOC of 1.02 V, a fill factor (FF%) of 68.2%, and an η% of 15.3% despite the sputtering damage of the RT-sputtered ZnO deposition. Moreover, the RT-sputtered ZnO could function as a diffusion barrier for Al, moisture, and O2. The inorganic inverted CH3NH3PbI3 perovskite-based SCs demonstrated improved storage reliability.

  3. Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

    Science.gov (United States)

    Pool, Vanessa L.; Dou, Benjia; Van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

    2017-01-01

    Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 °C, can be significantly reduced to 40 s at 170 °C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2. PMID:28094249

  4. The Luminescence of CH3 NH3 PbBr3 Perovskite Nanoparticles Crests the Summit and Their Photostability under Wet Conditions is Enhanced.

    Science.gov (United States)

    Gonzalez-Carrero, Soranyel; Francés-Soriano, Laura; González-Béjar, María; Agouram, Saïd; Galian, Raquel E; Pérez-Prieto, Julia

    2016-10-01

    CH 3 NH 3 PbBr 3 perovskite nanoparticles (P AD ) are prepared with a photoluminescence quantum yield of ≈100% in air atmosphere by using the quasi-spherical shaped 2-adamantylammonium bromide (ADBr) as the only capping ligand. The photostability under wet conditions of this kind of nanoparticles is enhanced by using cucurbit[7]uril-adamantylammonium (AD@CB) host-guest complexes as the capping ligand. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes

    Science.gov (United States)

    Xu, Jixian; Buin, Andrei; Ip, Alexander H.; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J.; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G.; Maksymovych, Peter; Sargent, Edward H.

    2015-05-01

    Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3- antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.

  6. Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes.

    KAUST Repository

    Xu, Jixian

    2015-05-08

    Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3(-) antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.

  7. Magnetic properties of rare earth oxides with perovskite structure

    International Nuclear Information System (INIS)

    Hinatsu, Yukio

    2008-01-01

    A perovskite composite oxide is represented by the general formula of ABO 3 . Cations at the B site characterize magnetic properties of the oxide. Many studies have been accumulated for transition metal elements at the B sites. In this report the studies of rare earth elements at the B sites are reviewed. In rare elements, tetravalent ions such as Ce 4+ , Pr 4+ and Tb 4+ can occupy the B sites with Ba and Sr ions at the A sites. Both the SrTbO 3 and BaTbO 3 have an orthorhombic structure and show the antiferromagnetic transition at about 33 K, which is originated from terbium ions coupled antiferromagnetically with the six neighboring terbium ions. A tetravalent praseodymium perovskite SrPrO 3 shows no existence of the magnetic ordering down to 2.0 K. This is in contrast to the result of isomorphous BaPrO 3 , which shows an antiferromagnetic transition at 11.5 K. A double perovskite structure is represented by the formula A 2 LnMO 6 (A=Ba, Sr, Ca; M=Ru, Ir). In a double perovskite compound Ba 2 PrRuO 6 , the Pr 3+ and Ru 5+ ions are arranged with regularity over the six-coordinate B sites. This compound transforms to an antiferromagnetic state below 117 K. Antiferromagnetic transition temperatures T N for isomorphous Sr and Ca show a clear tendency, T N (A=Ba)>T N (Sr)>T N (Ca), in the compounds with the same rare earth elements (Ln). The 6H-perovskite structure Ba 3 LnRu 2 O 9 consists of linkages between LnO 6 octahedra and Ru 2 O 9 dimers made from face-shared RuO 6 octahedra. The 6H-perovskite structure Ba 3 MRu 2 O 9 (M=Sc, Y, La, Nd-Gd, Dy-Lu) have the valence state of Ba 3 M 3+ Ru 2 4.5+ O 9 . The magnetic susceptibilities show a broad maximum at 135-370 K. This magnetic behavior is ascribed to the antiferromagnetic coupling between two Ru ions in a Ru 2 O 9 dimer and to the magnetic interaction between the Ru 2 O 9 dimers. (author)

  8. Control of oleylamine to perovskite ratio in synthesis of MAPbBr3 nanoparticles

    Science.gov (United States)

    Huang, Jing; Wu, Yi-Hua; Zhu, Zhi-Gang; Shih, Wan Y.; Shih, Wei-Heng

    2018-06-01

    Methylammonium lead bromide (CH3NH3PbBr3) nanocrystals have great potentials for lighting and display applications. Previously we synthesized CH3NH3PbBr3 nanocrystals using oleylamine as capping molecule and found that by increasing the oleylamine to CH3NH3PbBr3 perovskite ratio (OPR), the photoluminescence wavelengths and morphology of CH3NH3PbBr3 nanocrystals could be varied from 530 nm (green) platelets to 460 nm (blue) particles. Here we modified the synthesis to direct injection of precursors into toluene and found that increasing OPR not only changes the wavelength and morphology of nanocrystals but also the size of the unit cells.

  9. LaMn1-xFe xO3 and LaMn0.1-xFe0.90Mo x O3 perovskites: synthesis, characterization and catalytic activity in H2O2 reactions

    Directory of Open Access Journals (Sweden)

    Fabiano Magalhães

    2008-09-01

    Full Text Available In this work two perovskites were prepared: LaMn1-xFe xO3, and LaMn0.1-x Fe0.90Mo xO3. XRD and Mössbauer spectroscopy suggest the formation of pure phase perovskite with the incorporation of Fe and Mo in the structure. The catalytic activity of these materials was studied in two reactions with H2O2: the decomposition to O2, and the oxidation of the model organic contaminant methylene blue. The perovskite composition strongly affects the catalytic activity, while Fe decreases the H2O2 decomposition Mo strongly improves dye oxidation.

  10. Silver copper fluoride: A novel perovskite cathode for lithium batteries

    Science.gov (United States)

    Tong, Wei; Amatucci, Glenn G.

    2017-09-01

    An electrochemically active nanostructured silver copper fluoride (SCF) perovskite, AgCuF3, was synthesized via a mechanochemical reaction between AgF and CuF2 precursors. Phase composition and electrochemical properties of the SCF perovskites produced under various synthetic parameters were studied. The optimum SCF perovskite sample exhibited an appreciable electrochemical performance through the use of conductive carbon matrix in a primary lithium half cell. A high specific capacity of 270 mAh g-1 was achieved at a cutoff voltage of 2 V with 190 mAh g-1 above 3 V, leading to a total volumetric energy density of 3666 Wh L-1 at >3 V and 4848 Wh L-1 at >2 V.

  11. Coherent intergrowth of simple cubic and quintuple tetragonal perovskites in the system Nd{sub 2−ε}Ba{sub 3+ε}(Fe{sub ,}Co){sub 5}O{sub 15−δ}

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Asish K. [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France); Yu Mychinko, Mikhail [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France); Department of Chemistry, Institute of Natural Sciences, Ural Federal University, Lenin av. 51, Yekaterinburg 620000 (Russian Federation); Caignaert, Vincent; Lebedev, Oleg I. [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France); Volkova, Nadezhda E.; Deryabina, Ksenia M.; Cherepanov, Vladimir A. [Department of Chemistry, Institute of Natural Sciences, Ural Federal University, Lenin av. 51, Yekaterinburg 620000 (Russian Federation); Raveau, Bernard, E-mail: bernard.raveau@ensicaen.fr [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France)

    2015-11-15

    Investigation of the Nd{sub 2−ε}Ba{sub 3+ε}(Fe,Co){sub 5}O{sub 15−δ} system, combining X-ray diffraction and electron microscopy, has allowed a tetragonal quintuple ordered perovskite “a{sub p}×a{sub p}×5a{sub p}” phasoid inter-grown within a single cubic perovskite matrix to be evidenced for ε=0. This nanoscale chemically twinned perovskite is compared with other members, Ln=Sm, Eu, Pr. The unusual long range ordering of the layers develops strains due to size mismatch between Ba{sup 2+} and Ln{sup 3+} cations. Importantly, two factors allow the strains to be decreased: (i) special intergrowths of double (LnBaFe{sub 2}O{sub 6−δ}) and triple (LnBa{sub 2}Fe{sub 3}O{sub 9−δ}) perovskite ribbons/layers oriented at 90°, (ii) nanoscale chemical twinning. The spin locking effect of the nano-domain boundaries upon the magnetic properties of these perovskites is discussed. - Graphical abstract: Nd{sub 2}Ba{sub 3}Fe{sub 5}O{sub 14.54} is a tetragonal quintuple perovskite phasoid embedded in a simple cubic perovskite matrix, which shows collinear antiferromagnetic behavior.

  12. Potassium doped methylammonium lead iodide (MAPbI3) thin films as a potential absorber for perovskite solar cells; structural, morphological, electronic and optoelectric properties

    Science.gov (United States)

    Muzammal uz Zaman, Muhammad; Imran, Muhammad; Saleem, Abida; Kamboh, Afzal Hussain; Arshad, Muhammad; Khan, Nawazish Ali; Akhter, Parvez

    2017-10-01

    In this article, we have demonstrated the doping of K in the light absorbing CH3NH3PbI3 perovskite i.e. (M = CH3, A = NH3; x = 0-1). One of the major merits of methylammonium lead iodide (CH3NH3PbI3) perovskites is that they act as efficient absorbing material of light in photovoltaic cell imparting long carrier lifetime and optimum band gap. The structural, morphological, electronic and optoelectric properties of potassium (K) doped light absorber methylammonium lead iodide (CH3NH3PbI3) perovskites are reported here i.e. Kx(MA)1-xPbI3 (M = CH3, A =NH3; x = 0-1). The thin films of perovskites (x = 0-1) were deposited by spin coating on cleaned FTO substrates and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), current-voltage (IV), X-ray photoelectron spectroscopy (XPS) and Diffused reflectance spectroscopy (DRS) analysis. The organic constituents i.e. MA = CH3NH3, in perovskites solar cells induce instability even at the room temperature. To overcome such instabilities we have replaced the organic constituents by K because both of them have electropositive nature. Potassium successfully replaces the CH3NH3. Initially, this compound grows in a tetragonal crystal structure, however, beyond 30% doping of potassium orthorhombic distortions are induced in the parent tetragonal unit cell. Such phase transformation is microscopically visible in the electron micrographs of doped samples; cubic grains for MAPbI3 begin to transform into strip like structures in K-doped samples. The resistance of the samples is decreased for partial K-doping, which we suggested to be arising due to the electropositive nature of K. It is observed that the binding energy difference between Pb4f and I3d core levels are very similar in all the investigated systems and show formal oxidation states. Also, the partially doped samples showed increased absorption and bandgaps around 1.5 eV which is an optimum value for solar absorption.

  13. Studies of Fe-Co based perovskite cathodes with different A-site cations

    DEFF Research Database (Denmark)

    Kammer Hansen, K.

    2006-01-01

    Iron-cobalt based perovskite cathodes with different A-site cations ((Ln(0.6)Sr(0.4))(0.99)Fe0.8Co0.2O3-delta, where Ln is La, Pr, Sm or Gd) have been synthesised, characterised by a powder XRD, dilatometry, 4-point DC conductivity measurements, and electrochemical impedance spectroscopy (EIS......) on cone shaped electrodes. In addition to this scanning electron microscopy (SEM) was used to characterise the bars. XRD revealed that only the La-containing perovskite was hexagonal. The Pr and Sm perovskites were orthorhombic. The gadolinium-based perovskite was a two phase system consisting...... of an orthorhombic and a cubic perovskite phase. The thermal expansion coefficient (TEC) increased systematically with a decrease in the size of the A-site cation until the gadoliniurn-containing perovskite where the TEC decreases abruptly. The total electric conductivity was the highest for the La-based perovskite...

  14. Synthesis and structural study of the transition metal doped rhodium perovskites

    International Nuclear Information System (INIS)

    Ting, J.; Kennedy, B.; Zhang, Z.

    2009-01-01

    Full text: One of the most common structures encountered in solid state chemistry is the perovskite structure. With a general formula of AB0 3, the A-type cations are 12-coordinate within a cubo-octahedral environment, while the B-type cations are 6-coordinate, forming an interconnecting three-dimensional octahedral network with neighbouring oxygen anions. While the ideal perovskite structure is cubic in Pm 3 m, many perovskites exhibit symmetry lowering tilting of the corner-sharing B0 6o ctahedral units as a result of A- and B-type cation size disparity. This is also evident in substituted perovskites, where two cations occupy the smaller octahedral site, AB 1- xB' x0 3' Electronic effects can also lower the symmetry. The two most commonly observed effects are the polarisation of the B-cation with a d 0 electronic configuration and Jahn-Teller distortion where the B-cation has a d 4 or d 9 electronic configuration, such as Mn 3+ or Cu 2+ respectively. Manganese containing perovskites have been shown in some compounds to exhibit long-range orbital ordering, giving rise to interesting properties. Heavier transition metals such as ruthenium and iridium have been previously incorporated into these perovskites as an avenue to regulate the properties of these materials. Two orthorhombic rhodium perovskite structures are presented, LaMn 0 . 5 Rh 0 . 5 O 3 and LaCu 05 Rh 0 . 5 O 3 ' A combination of synchrotron x-ray and neutron powder diffraction has been used to elucidate their structures, and have shown both B- and B'-type cations to be disordered across the same crystallographic site for both compounds. x-ray absorption spectroscopy measurements have been used to provide an insight into the valence states of the cations, which show a valency of +3.5 for rhodium due to an extensive charge delocalisation between copper and rhodium.

  15. Electrosynthesized polyaniline for the corrosion protection of aluminum alloy 2024-T3

    Directory of Open Access Journals (Sweden)

    Huerta-Vilca Domingo

    2003-01-01

    Full Text Available Adherent polyaniline films on aluminum alloy 2024-T3 have been prepared by electrodeposition from aniline containing oxalic acid solution. The most appropriate method to prepare protective films was a successive galvanostatic deposition of 500 seconds. With this type of film, the open circuit potential of the coating shifted around 0.065V vs. SCE compared to the uncoated alloy. The polyaniline coatings can be considered as candidates to protect copper-rich (3 - 5% aluminum alloys by avoiding the galvanic couple between re-deposited copper on the surface and the bulk alloy. The performance of the polyaniline films was verified by immersion tests up to 2.5 months. It was good with formation of some aluminum oxides due to electrolyte permeation so, in order to optimize the performance a coating formulation would content an isolation topcoat.

  16. Synthesis under pressure and characterizations through optical spectroscopy of jahn-teller cations (LS Ni3+, is Co3+) as probes diluted in a perovskite matrix

    Science.gov (United States)

    Sanz-Ortiz, M. N.; Rodríguez, F.; Baranov, A.; Demazeau, G.

    2008-07-01

    The objective is to explore through optical spectroscopy and magnetic measurements the coordination and electronic structures of transition-metal ions introduced as impurities with unusual valence states in the oxide perovskite LaAlO3. The selected transition-metal ions Ni3+(3d7) and Co3+(3d6) are characterized by an electronic configuration likely leading to an orbital degenerate E state in Oh symmetry, and thus electron-lattice coupling due to the Jahn-Teller effect may induce low symmetry distortion around the impurity oxygen octahedron. We show that a sol-gel process followed by high oxygen pressure treatments yields stabilization of trivalent state in oxide perovskite. Information about the coordination, electronic structure and aggregation around the magnetic impurity was obtained from X-ray diffraction, FTIR and optical spectroscopy. Finally, evidence on the possible existence of intermediate spin state in Co3+ is under consideration.

  17. Synthesis under pressure and characterizations through optical spectroscopy of jahn-teller cations (LS Ni3+, is Co3+) as probes diluted in a perovskite matrix

    International Nuclear Information System (INIS)

    Sanz-Ortiz, M N; RodrIguez, F; Baranov, A; Demazeau, G

    2008-01-01

    The objective is to explore through optical spectroscopy and magnetic measurements the coordination and electronic structures of transition-metal ions introduced as impurities with unusual valence states in the oxide perovskite LaAlO 3 . The selected transition-metal ions Ni 3+ (3d 7 ) and Co 3+ (3d 6 ) are characterized by an electronic configuration likely leading to an orbital degenerate E state in Oh symmetry, and thus electron-lattice coupling due to the Jahn-Teller effect may induce low symmetry distortion around the impurity oxygen octahedron. We show that a sol-gel process followed by high oxygen pressure treatments yields stabilization of trivalent state in oxide perovskite. Information about the coordination, electronic structure and aggregation around the magnetic impurity was obtained from X-ray diffraction, FTIR and optical spectroscopy. Finally, evidence on the possible existence of intermediate spin state in Co 3+ is under consideration

  18. Piezoelectric scattering limited mobility of hybrid organic-inorganic perovskites CH3NH3PbI3

    Science.gov (United States)

    Lu, Ying-Bo; Kong, Xianghua; Chen, Xiaobin; Cooke, David G.; Guo, Hong

    2017-01-01

    Carrier mobility is one of the most important parameters for semiconducting materials and their use in optoelectronic devices. Here we report a systematic first principles analysis of the acoustic phonon scattering mechanism that limits the mobility of CH3NH3PbI3 (MAPbI3) perovskites. Due to the unique hybrid organic-inorganic structure, the mechanical, electronic and transport properties are dominated by the same factor, i.e. the weak interatomic bond and the easy rotation of methylammonium (MA) molecules under strain. Both factors make MAPbI3 soft. Rotation of MA molecule induces a transverse shift between Pb and I atoms, resulting in a very low deformation potential and a strong piezoelectricity in MAPbI3. Hence the carrier mobility of pristine MAPbI3 is limited by the piezoelectric scattering, which is consistent to the form of its temperature dependence. Our calculations suggest that in the pristine limit, a high mobility of about several thousand cm2 V−1 S−1 is expected for MAPbI3. PMID:28150743

  19. Crystalline orientation dependent photoresponse and heterogeneous behaviors of grain boundaries in perovskite solar cells

    Science.gov (United States)

    Jiang, Chuanpeng; Zhang, Pengpeng

    2018-02-01

    Using photoconductive atomic force microscopy and Kelvin probe force microscopy, we characterize the local electrical properties of grains and grain boundaries of organic-inorganic hybrid perovskite (CH3NH3PbI3) thin films on top of a poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS)/ITO substrate. Three discrete photoconductivity levels are identified among perovskite grains, likely corresponding to the crystal orientation of each grain. Local J-V curves recorded on these grains further suggest an anti-correlation behavior between the short circuit current (JSC) and open circuit voltage (VOC). This phenomenon can be attributed to diffusion-limited surface recombination at the non-selective perovskite-tip contact, where a higher carrier mobility established in the perovskite grain results in an enhanced surface recombination and thus a lower VOC. In addition, the photoresponse of perovskite films displays a pronounced heterogeneity across the grain boundaries, with the boundaries formed between grains of the same photoconductivity level displaying even enhanced photocurrent and open circuit voltage compared to those of the adjacent grain interiors. These observations highlight the significance of controlling the microstructure of perovskite thin films, which will be a necessary route for further improving the efficiency of perovskite solar cells.

  20. Thermally induced A'-A site exchange in novel layered perovskites Ag2[Ca1.5M3O10] (M = Nb, Ta).

    Science.gov (United States)

    Bhuvanesh, Nattamai S P; Woodward, Patrick M

    2002-12-04

    We have synthesized and characterized new layered perovskites Ag2[A1.5M3O10] (A = Ca, M = Nb, Ta), from their lithium analogues, by soft-chemical ion exchange. These oxides show topotactic irreversible thermally induced A'-A site exchange, resulting in Ag1.1Ca0.9[Ca0.6Ag0.9M3O10], conferred from our high-temperature X-ray and ionic conductivity studies. The latter phases are the first compounds where Ag+ ions reside in both A' and A sites in layered perovskites. The absence of similar phase transition for A = Sr suggests that these transitions strongly depend on the size, charge, and the coordination preference of A' and A cations. This result provides a new synthetic tool for modifying the occupation of the 12-coordinate A site of layered perovskites using soft chemical routes.

  1. Modified titanate perovskites in photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Wlodarczak, M.; Ludwiczak, M.; Laniecki, M. [A. Mickiewicz Univ. (Poland)

    2010-07-01

    Received materials have structure of perovskite, what was shown by XRD diffraction patterns. Perovskite structure is present in all samples with strontium, barium and one sample with calcium. Moreover, received barium and strontium titanate are very similar to pattern materials. XRD results show, that temperature 500 C is too low to create perovskite structure in CaTiO{sub 3}. However, it is high enough in case of SrTiO{sub 3} and BaTiO{sub 3}. One regularity is obvious, surface area increases for samples calcined in lower temperature. There is a connection between surface area and dispersion of platinum. Both of them reach the greatest value to the calcium titanate. Catalytic activity was shown by all of received samples. Measurable values were received to samples calcined in 700 C. Calcium titanate had the best catalytic activity, both an amount of hydrogen and a ratio of hydrogen to platinum. There is one regularity to all samples, the ration of hydrogen to platinum increase when amount of platinum decrease. (orig.)

  2. Perovskite classification: An Excel spreadsheet to determine and depict end-member proportions for the perovskite- and vapnikite-subgroups of the perovskite supergroup

    Science.gov (United States)

    Locock, Andrew J.; Mitchell, Roger H.

    2018-04-01

    Perovskite mineral oxides commonly exhibit extensive solid-solution, and are therefore classified on the basis of the proportions of their ideal end-members. A uniform sequence of calculation of the end-members is required if comparisons are to be made between different sets of analytical data. A Microsoft Excel spreadsheet has been programmed to assist with the classification and depiction of the minerals of the perovskite- and vapnikite-subgroups following the 2017 nomenclature of the perovskite supergroup recommended by the International Mineralogical Association (IMA). Compositional data for up to 36 elements are input into the spreadsheet as oxides in weight percent. For each analysis, the output includes the formula, the normalized proportions of 15 end-members, and the percentage of cations which cannot be assigned to those end-members. The data are automatically plotted onto the ternary and quaternary diagrams recommended by the IMA for depiction of perovskite compositions. Up to 200 analyses can be entered into the spreadsheet, which is accompanied by data calculated for 140 perovskite compositions compiled from the literature.

  3. CH(3)NH(3)PbI(3) perovskite / silicon tandem solar cells: characterization based optical simulations.

    Science.gov (United States)

    Filipič, Miha; Löper, Philipp; Niesen, Bjoern; De Wolf, Stefaan; Krč, Janez; Ballif, Christophe; Topič, Marko

    2015-04-06

    In this study we analyze and discuss the optical properties of various tandem architectures: mechanically stacked (four-terminal) and monolithically integrated (two-terminal) tandem devices, consisting of a methyl ammonium lead triiodide (CH(3)NH(3)PbI(3)) perovskite top solar cell and a crystalline silicon bottom solar cell. We provide layer thickness optimization guidelines and give estimates of the maximum tandem efficiencies based on state-of-the-art sub cells. We use experimental complex refractive index spectra for all involved materials as input data for an in-house developed optical simulator CROWM. Our characterization based simulations forecast that with optimized layer thicknesses the four-terminal configuration enables efficiencies over 30%, well above the current single-junction crystalline silicon cell record of 25.6%. Efficiencies over 30% can also be achieved with a two-terminal monolithic integration of the sub-cells, combined with proper selection of layer thicknesses.

  4. Role of the chemical substitution on the structural and luminescence properties of the mixed halide perovskite thin MAPbI_3_−_xBr_x (0 ≤ x ≤ 1) films

    International Nuclear Information System (INIS)

    Atourki, Lahoucine; Vega, Erika; Marí, Bernabé; Mollar, Miguel; Ait Ahsaine, Hassan; Bouabid, Khalid; Ihlal, Ahmed

    2016-01-01

    Highlights: • X-ray diffraction analyses indicate the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m across in the composition range of 0.6 ≤ x ≤ 1. • Perovskite films exhibit a very high absorbance in the visible and short infrared. • As the fraction of bromide change, the adsorption edge of thin film perovskite can be tuned along the visible spectrum from 543 nm to 785 nm. • The incorporating of bromide into MAPbI_3_−_xBr_x shifts the PL emission to shorter wavelengths. - Abstract: Mixed bromide iodide lead perovskites were prepared from methylamine, lead nitrate and the corresponding hydroX acid (X = I, Br), they were then deposited as thin films on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a tetragonal phase I4/mcm up to x = 0.4 and a cubic perovskite with space group Pm3 m in the composition range of 0.6 ≤ x ≤ 1. Mixed lead perovskites showed a high absorbance in the UV–vis range. The band gap energy of thin films were estimated from absorbance spectral measurements, it was found that the onset of the absorption edge for MAPbI_3_−_xBr_x (x < 1) thin films is ranging between 1.58 to 1.72 eV. Photoluminescence emission energies for mixed halide perovskites presented intermediate values from 781 nm (MAPbI_3) to 545 nm (MAPbBr_3).

  5. Temperature Dependent Charge Carrier Dynamics in Formamidinium Lead Iodide Perovskite

    NARCIS (Netherlands)

    Gelvez Rueda, M.C.; Renaud, N.; Grozema, F.C.

    2017-01-01

    The fundamental opto-electronic properties of organic-inorganic hybrid perovskites are strongly affected by their structural parameters. These parameters are particularly critical in formamidinium lead iodide (FAPbI3), in which its large structural disorder leads to a non-perovskite

  6. Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

    International Nuclear Information System (INIS)

    Bazuev, G.V.; Makarova, O.V.; Shvejkin, G.P.

    1983-01-01

    A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln 3 + cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm 3 size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balancewith electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti 3 + cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled π*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility

  7. Pressure-Induced Structural and Optical Properties of Inorganic Halide Perovskite CsPbBr3.

    Science.gov (United States)

    Zhang, Long; Zeng, Qingxin; Wang, Kai

    2017-08-17

    Perovskite photovoltaic materials are gaining sustained attention because of their excellent photovoltaic properties and extensive practical applicability. In this Letter, we discuss the changes in the structure and optical properties of CsPbBr 3 under high pressure. As the pressure increased, the band gap initially began to red shift before 1.0 GPa followed by a continuous blue shift until the crystal was completely amorphized. An isostructural phase transition at 1.2 GPa was determined by high-pressure synchrotron X-ray and Raman spectroscopy. The result could be attributed to bond length shrinkage and PbBr 6 octahedral distortion under high pressure. The amorphization of the crystal was due to the severe distortion and tilt of the PbBr 6 octahedron, leading to broken long-range order. Changes in optical properties are closely related to the evolution of the crystal structure. Our discussion shows that high-pressure study can be used as an effective means to tune the structure and properties of all-inorganic halide perovskites.

  8. Lead Acetate Based Hybrid Perovskite Through Hot Casting for Planar Heterojunction Solar Cells

    Science.gov (United States)

    Shin, Gwang Su; Choi, Won-Gyu; Na, Sungjae; Gökdemir, Fatma Pinar; Moon, Taeho

    2018-03-01

    Flawless coverage of a perovskite layer is essential in order to achieve realistic high-performance planar heterojunction solar cells. We present that high-quality perovskite layers can be efficiently formed by a novel hot casting route combined with MAI (CH3NH3I) and non-halide lead acetate (PbAc2) precursors under ambient atmosphere. Casting temperature is controlled to produce various perovskite microstructures and the resulted crystalline layers are found to be comprised of closely packed islands with a smooth surface structure. Lead acetate employed perovskite solar cells are fabricated using PEDOT:PSS and PCBM charge transporting layers, in p- i- n type planar architecture. Especially, the outstanding open-circuit voltage demonstrates the high crystallinity and dense coverage of the produced perovskite layers by this facile route.

  9. Understanding perovskite formation through the intramolecular exchange method in ambient conditions

    Science.gov (United States)

    Szostak, Rodrigo; Castro, Jhon A. P.; Marques, Adriano S.; Nogueira, Ana F.

    2017-04-01

    Among the methods to prepare hybrid organic-inorganic perovskite films, the intramolecular exchange method was the first one that made possible to prepare perovskite solar cells with efficiencies higher than 20%. However, perovskite formation by this method is not completely understood, especially in ambient conditions. In this work, perovskite films were prepared by the intramolecular exchange method in ambient conditions. The spin coating speed and the frequency of the MAI solution dripping onto PbI2(DMSO) were varied during the deposition steps. With the combination of these two parameters, a rigid control of the solvent drying was possible. Thus, depending on the chosen conditions, the intermediate MAPb3I8·2DMSO was formed with residual PbI2. Otherwise, direct formation of perovskite film was attained. A mechanism for the direct formation of bulk perovskite was proposed. We also investigated how the posterior thermal annealing affects the crystallinity and defects in perovskite films. With prolonged thermal annealing, the excess of MAI can be avoided, increasing the efficiency and decreasing the hysteresis of the solar cells. The best perovskite solar cell achieved a stabilized power output of 12.9%. The findings of this work pave the way for realizing the fabrication of efficient perovskite solar cells in ambient atmosphere, a very desirable condition for cost-efficient large scale manufacturing of this technology.

  10. Highly Efficient and Stable Sn-Rich Perovskite Solar Cells by Introducing Bromine.

    Science.gov (United States)

    Lee, Seojun; Kang, Dong-Won

    2017-07-12

    Compositional engineering of recently arising methylammonium (MA) lead (Pb) halide based perovskites is an essential approach for finding better perovskite compositions to resolve still remaining issues of toxic Pb, long-term instability, etc. In this work, we carried out crystallographic, morphological, optical, and photovoltaic characterization of compositional MASn 0.6 Pb 0.4 I 3-x Br x by gradually introducing bromine (Br) into parental Pb-Sn binary perovskite (MASn 0.6 Pb 0.4 I 3 ) to elucidate its function in Sn-rich (Sn:Pb = 6:4) perovskites. We found significant advances in crystallinity and dense coverage of the perovskite films by inserting the Br into Sn-rich perovskite lattice. Furthermore, light-intensity-dependent open circuit voltage (V oc ) measurement revealed much suppressed trap-assisted recombination for a proper Br-added (x = 0.4) device. These contributed to attaining the unprecedented power conversion efficiency of 12.1% and V oc of 0.78 V, which are, to the best of our knowledge, the highest performance in the Sn-rich (≥60%) perovskite solar cells reported so far. In addition, impressive enhancement of photocurrent-output stability and little hysteresis were found, which paves the way for the development of environmentally benign (Pb reduction), stable monolithic tandem cells using the developed low band gap (1.24-1.26 eV) MASn 0.6 Pb 0.4 I 3-x Br x with suggested composition (x = 0.2-0.4).

  11. The nature of dynamic disorder in lead halide perovskite crystals (Conference Presentation)

    Science.gov (United States)

    Yaffe, Omer; Guo, Yinsheng; Hull, Trevor; Stoumpos, Costas; Tan, Liang Z.; Egger, David A.; Zheng, Fan; Szpak, Guilherme; Semonin, Octavi E.; Beecher, Alexander N.; Heinz, Tony F.; Kronik, Leeor; Rappe, Andrew M.; Kanatzidis, Mercouri G.; Owen, Jonathan S.; Pimenta, Marcos A.; Brus, Louis E.

    2016-09-01

    We combine low frequency Raman scattering measurements with first-principles molecular dynamics (MD) to study the nature of dynamic disorder in hybrid lead-halide perovskite crystals. We conduct a comparative study between a hybrid (CH3NH3PbBr3) and an all-inorganic lead-halide perovskite (CsPbBr3). Both are of the general ABX3 perovskite formula, and have a similar band gap and structural phase sequence, orthorhombic at low temperature, changing first to tetragonal and then to cubic symmetry as temperature increases. In the high temperature phases, we find that both compounds show a pronounced Raman quasi-elastic central peak, indicating that both are dynamically disordered.

  12. Critical Intermediate Structure That Directs the Crystalline Texture and Surface Morphology of Organo-Lead Trihalide Perovskite.

    Science.gov (United States)

    Chia, Hao-Chung; Sheu, Hwo-Shuenn; Hsiao, Yu-Yun; Li, Shao-Sian; Lan, Yi-Kang; Lin, Chung-Yao; Chang, Je-Wei; Kuo, Yen-Chien; Chen, Chia-Hao; Weng, Shih-Chang; Su, Chun-Jen; Su, An-Chung; Chen, Chun-Wei; Jeng, U-Ser

    2017-10-25

    We have identified an often observed yet unresolved intermediate structure in a popular processing with dimethylformamide solutions of lead chloride and methylammonium iodide for perovskite solar cells. With subsecond time-resolved grazing-incidence X-ray scattering and X-ray photoemission spectroscopy, supplemental with ab initio calculation, the resolved intermediate structure (CH 3 NH 3 ) 2 PbI 2 Cl 2 ·CH 3 NH 3 I features two-dimensional (2D) perovskite bilayers of zigzagged lead-halide octahedra and sandwiched CH 3 NH 3 I layers. Such intermediate structure reveals a hidden correlation between the intermediate phase and the composition of the processing solution. Most importantly, the 2D perovskite lattice of the intermediate phase is largely crystallographically aligned with the [110] planes of the three-dimensional perovskite cubic phase; consequently, with sublimation of Cl ions from the organo-lead octahedral terminal corners in prolonged annealing, the zigzagged octahedral layers of the intermediate phase can merge with the intercalated methylammonium iodide layers for templated growth of perovskite crystals. Regulated by annealing temperature and the activation energies of the intermediate and perovskite, deduced from analysis of temperature-dependent structural kinetics, the intermediate phase is found to selectively mature first and then melt along the layering direction for epitaxial conversion into perovskite crystals. The unveiled epitaxial conversion under growth kinetics controls might be general for solution-processed and intermediate-templated perovskite formation.

  13. Oxygen permeability of perovskite-type BaBi1-xLaxO3

    International Nuclear Information System (INIS)

    Yaremchenko, A.A.; Kharton, V.V.; Viskup, A.P.; Naumovich, E.N.; Samokhval, V.V.

    1998-01-01

    Oxygen permeability, electrical conductivity, and thermal expansion of BaBi 1-x La x O 3-δ (x = 0, 0.2, and 0.4) perovskite-like solid solutions have been found to decrease with lanthanum content. Thermal expansion coefficients of the ceramics are (11.9--12.8) x 10 -6 K -1 . Oxygen transport through the BaBi(La)O 3-δ dense ceramic membranes within the membrane thickness range of 0.6 < d < 1.2 mm has been shown to be limited by both bulk ionic conductivity and surface exchange rate

  14. A Strategy for Architecture Design of Crystalline Perovskite Light-Emitting Diodes with High Performance.

    Science.gov (United States)

    Shi, Yifei; Wu, Wen; Dong, Hua; Li, Guangru; Xi, Kai; Divitini, Giorgio; Ran, Chenxin; Yuan, Fang; Zhang, Min; Jiao, Bo; Hou, Xun; Wu, Zhaoxin

    2018-06-01

    All present designs of perovskite light-emitting diodes (PeLEDs) stem from polymer light-emitting diodes (PLEDs) or perovskite solar cells. The optimal structure of PeLEDs can be predicted to differ from PLEDs due to the different fluorescence dynamics and crystallization between perovskite and polymer. Herein, a new design strategy and conception is introduced, "insulator-perovskite-insulator" (IPI) architecture tailored to PeLEDs. As examples of FAPbBr 3 and MAPbBr 3 , it is experimentally shown that the IPI structure effectively induces charge carriers into perovskite crystals, blocks leakage currents via pinholes in the perovskite film, and avoids exciton quenching simultaneously. Consequently, as for FAPbBr 3 , a 30-fold enhancement in the current efficiency of IPI-structured PeLEDs compared to a control device with poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) as hole-injection layer is achieved-from 0.64 to 20.3 cd A -1 -while the external quantum efficiency is increased from 0.174% to 5.53%. As the example of CsPbBr 3 , compared with the control device, both current efficiency and lifetime of IPI-structured PeLEDs are improved from 1.42 and 4 h to 9.86 cd A -1 and 96 h. This IPI architecture represents a novel strategy for the design of light-emitting didoes based on various perovskites with high efficiencies and stabilities. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Organic-Inorganic Perovskites: Structural Versatility for Functional Materials Design.

    Science.gov (United States)

    Saparov, Bayrammurad; Mitzi, David B

    2016-04-13

    Although known since the late 19th century, organic-inorganic perovskites have recently received extraordinary research community attention because of their unique physical properties, which make them promising candidates for application in photovoltaic (PV) and related optoelectronic devices. This review will explore beyond the current focus on three-dimensional (3-D) lead(II) halide perovskites, to highlight the great chemical flexibility and outstanding potential of the broader class of 3-D and lower dimensional organic-based perovskite family for electronic, optical, and energy-based applications as well as fundamental research. The concept of a multifunctional organic-inorganic hybrid, in which the organic and inorganic structural components provide intentional, unique, and hopefully synergistic features to the compound, represents an important contemporary target.

  16. Hybrid perovskites: Approaches towards light-emitting devices

    KAUST Repository

    Alias, Mohd Sharizal

    2016-10-06

    The high optical gain and absorption of organic-inorganic hybrid perovskites have attracted extensive research for photonic device applications. Using the bromide halide as an example, we present key approaches of our work towards realizing efficient perovskites based light-emitters. The approaches involved determination of optical constants for the hybrid perovskites thin films, fabrication of photonic nanostructures in the form of subwavelength grating reflector patterned directly on the hybrid perovskites as light manipulation layer, and enhancing the emission property of the hybrid perovskites by using microcavity structure. Our results provide a platform for realization of hybrid perovskites based light-emitting devices for solid-state lighting and display applications. © 2016 IEEE.

  17. Hybrid perovskites: Approaches towards light-emitting devices

    KAUST Repository

    Alias, Mohd Sharizal; Dursun, Ibrahim; Priante, Davide; Saidaminov, Makhsud I.; Ng, Tien Khee; Bakr, Osman; Ooi, Boon S.

    2016-01-01

    The high optical gain and absorption of organic-inorganic hybrid perovskites have attracted extensive research for photonic device applications. Using the bromide halide as an example, we present key approaches of our work towards realizing efficient perovskites based light-emitters. The approaches involved determination of optical constants for the hybrid perovskites thin films, fabrication of photonic nanostructures in the form of subwavelength grating reflector patterned directly on the hybrid perovskites as light manipulation layer, and enhancing the emission property of the hybrid perovskites by using microcavity structure. Our results provide a platform for realization of hybrid perovskites based light-emitting devices for solid-state lighting and display applications. © 2016 IEEE.

  18. Continuous-wave optically pumped green perovskite vertical-cavity surface-emitter

    KAUST Repository

    Alias, Mohd Sharizal

    2017-09-11

    We report an optically pumped green perovskite vertical-cavity surface-emitter operating in continuous-wave (CW) with a power density threshold of ~89 kW/cm2. The device has an active region of CH3NH3PbBr3 embedded in a dielectric microcavity; this feat was achieved with a combination of optimal spectral alignment of the optical cavity modes with the perovskite optical gain, an adequate Q-factor of the microcavity, adequate thermal stability, and improved material quality with a smooth, passivated, and annealed thin active layer. Our results signify a way towards efficient CW perovskite emitter operation and electrical injection using low-cost fabrication methods for addressing monolithic optoelectronic integration and lasing in the green gap.

  19. Band-gap engineering of functional perovskites through quantum confinement and tunneling

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Pandey, Mohnish; Thygesen, Kristian Sommer

    2015-01-01

    An optimal band gap that allows for a high solar-to-fuel energy conversion efficiency is one of the key factors to achieve sustainability. We investigate computationally the band gaps and optical spectra of functional perovskites composed of layers of the two cubic perovskite semiconductors BaSnO3...... and BaTaO2N. Starting from an indirect gap of around 3.3 eV for BaSnO3 and a direct gap of 1.8 eV for BaTaO2N, different layerings can be used to design a direct gap of the functional perovskite between 2.3 and 1.2 eV. The variations of the band gap can be understood in terms of quantum confinement...

  20. Helium trapping in aluminum and sintered aluminum powders

    International Nuclear Information System (INIS)

    Das, S.K.; Kaminsky, M.; Rossing, T.

    1975-01-01

    The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV 4 He + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was observed from that in pure annealed aluminum. In order to determine whether the observed reduction in blistering is due to enhanced helium trapping or due to helium released, the implanted helium profiles in annealed aluminum and in SAP have been studied by Rutherford backscattering. The results show that more helium is trapped in SAP than in aluminum for identical irradiation conditions. The observed reduction in erosion from helium blistering in SAP is more likely due to the dispersion of trapped helium at the large Al-Al 2 O 3 interfaces and at the large grain boundaries in SAP than to helium release

  1. Effect of LiNO3 on corrosion prevention of aluminum wastes after their land disposal

    International Nuclear Information System (INIS)

    Matsuo, Toshiaki; Matsuda, Masami; Hironaga, Michihiko; Horikawa, Yoshihiko.

    1996-01-01

    After their land disposal, LiNO 3 added to cement solidified miscellaneous wastes inhibits hydrogen gas generation due to alkaline corrosion of aluminum contained in the wastes. We considered the presence of an Li-Al preservation film prevents hydrogen gas generation, and then, we assumed a scenario in which the amount of LiNO 3 included in the waste packages is lowered by underground water penetration, resulting in dissolution of the Li-Al preservation film. This dissolution allows the alkaline underground water to reach and corrode the aluminum materials. The loss of Na 2 O and K 2 O in cement by underground water penetration lowers the pH, so that the aluminum corrosion in the waste packages with LiNO 3 , expected when the Li-Al preservation film dissolves, is less than that without LiNO 3 . To test this scenario, we measured solubility of the Li-Al preservation film, Li + ion concentration, pH variation by underground water penetration, and aluminum corrosion when the Li-Al preservation film had dissolved. The measured solubility of the Li-Al preservation film was 3x10 -4 M at 283 K. At that time, pH was lowered from 12.9-13.0 to 12.2-12.3. As a result, with LiNO 3 addition the aluminum corrosion amount was reduced to 10% of that without LiNO 3 addition, because of the pH decrease. (author)

  2. Compositionally Graded Absorber for Efficient and Stable Near-Infrared-Transparent Perovskite Solar Cells.

    Science.gov (United States)

    Fu, Fan; Pisoni, Stefano; Weiss, Thomas P; Feurer, Thomas; Wäckerlin, Aneliia; Fuchs, Peter; Nishiwaki, Shiro; Zortea, Lukas; Tiwari, Ayodhya N; Buecheler, Stephan

    2018-03-01

    Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se 2 , CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite solar cells under long-term heat/light soaking has not been demonstrated. In this study, a facile partial ion-exchange approach is reported to achieve compositionally graded perovskite absorber layers. Incorporating compositional grading improves charge collection and suppresses interface recombination, enabling to fabricate near-infrared-transparent perovskite solar cells with power conversion efficiency of 16.8% in substrate configuration, and demonstrate 22.7% tandem efficiency with 3.3% absolute gain when mechanically stacked on a Cu(In,Ga)Se 2 bottom cell. Non-encapsulated graded perovskite device retains over 93% of its initial efficiency after 1000 h operation at maximum power point at 60 °C under equivalent 1 sun illumination. The results open an avenue in exploring partial ion-exchange to design graded perovskite solar cells with improved efficiency and stability.

  3. Compositionally Graded Absorber for Efficient and Stable Near‐Infrared‐Transparent Perovskite Solar Cells

    Science.gov (United States)

    Pisoni, Stefano; Weiss, Thomas P.; Feurer, Thomas; Wäckerlin, Aneliia; Fuchs, Peter; Nishiwaki, Shiro; Zortea, Lukas; Tiwari, Ayodhya N.

    2018-01-01

    Abstract Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se2, CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite solar cells under long‐term heat/light soaking has not been demonstrated. In this study, a facile partial ion‐exchange approach is reported to achieve compositionally graded perovskite absorber layers. Incorporating compositional grading improves charge collection and suppresses interface recombination, enabling to fabricate near‐infrared‐transparent perovskite solar cells with power conversion efficiency of 16.8% in substrate configuration, and demonstrate 22.7% tandem efficiency with 3.3% absolute gain when mechanically stacked on a Cu(In,Ga)Se2 bottom cell. Non‐encapsulated graded perovskite device retains over 93% of its initial efficiency after 1000 h operation at maximum power point at 60 °C under equivalent 1 sun illumination. The results open an avenue in exploring partial ion‐exchange to design graded perovskite solar cells with improved efficiency and stability. PMID:29593970

  4. Progress in the development of LuAlO$_{3}$ based scintillators

    CERN Document Server

    Belsky, A; Lecoq, P; Dujardin, C; Garnier, N; Canibano, H; Pédrini, C; Petrosian, A

    2000-01-01

    LuAlO/sub 3/:Ce/sup 3+/ (LuAP) and Lu/sub x/Y/sub 1/-xAlO/sub 3/:Ce /sup 3+/ (LuYAP) crystals are used as scintillation materials for positron emission tomography. The actual study of these scintillators develops in three directions: (i) growth of large size LuAP crystals with stable properties, (ii) the relationship between the composition of LuYAP crystals and scintillation properties, and (iii) scintillation mechanisms in lutetium compounds. After improving of growth conditions a large size samples (length >40 mm) have been prepared. Crystals show a good correlation between growth parameters, light yield and transmission spectra. We studied a series of samples with calibrated size (2*2*10 mm3) and compare the light yield with standard BGO and LSO samples. Mixed crystals with composition of 0.6

  5. Oxygen vacancies at the spinel/perovskite γ-Al{sub 2}O{sub 3}/SrTiO{sub 3} heterointerface probed by resonant photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schuetz, Philipp; Pfaff, Florian; Zapf, Michael; Gabel, Judith; Dudy, Lenart; Berner, Goetz; Sing, Michael; Claessen, Ralph [Physikalisches Institut and Roentgen Center for Complex Material Systems (RCCM), Universitaet Wuerzburg (Germany); Chen, Yunzhong; Pryds, Nini [Department of Energy Conversion and Storage, Technical University of Denmark, Risoe (Denmark); Schlueter, Christoph; Lee, Tien-Lin [Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot (United Kingdom)

    2016-07-01

    The spinel/perovskite heterointerface between the band insulators γ-Al{sub 2}O{sub 3} and SrTiO{sub 3} hosts a two-dimensional electron system (2DES) with exceptionally high electron mobility. Soft x-ray resonant photoelectron spectroscopy at the Ti L absorption edge is used to probe the Ti 3d derived interface states. Marked differences in the resonance behavior are found for the SrTiO{sub 3} valence band and the different interface states, which are observed in the band gap of SrTiO{sub 3}. A comparison to X-ray absorption spectra of Ti 3d{sup 0} and Ti 3d{sup 1} systems reveals the presence of different types of electronic states with Ti 3d character, i.e., oxygen vacancy induced, trapped in-gap states and itinerant states contributing to the 2DES. Exposure to low doses of oxygen during irradiation allows for the reversible manipulation of the oxygen stoichiometry, thus revealing the presence of an oxygen vacancy-induced state, which is characteristic for this spinel/perovskite interface.

  6. Progress on Perovskite Materials and Solar Cells with Mixed Cations and Halide Anions.

    Science.gov (United States)

    Ono, Luis K; Juarez-Perez, Emilio J; Qi, Yabing

    2017-09-13

    Organic-inorganic halide perovskite materials (e.g., MAPbI 3 , FAPbI 3 , etc.; where MA = CH 3 NH 3 + , FA = CH(NH 2 ) 2 + ) have been studied intensively for photovoltaic applications. Major concerns for the commercialization of perovskite photovoltaic technology to take off include lead toxicity, long-term stability, hysteresis, and optimal bandgap. Therefore, there is still need for further exploration of alternative candidates. Elemental composition engineering of MAPbI 3 and FAPbI 3 has been proposed to address the above concerns. Among the best six certified power conversion efficiencies reported by National Renewable Energy Laboratory on perovskite-based solar cells, five are based on mixed perovskites (e.g., MAPbI 1-x Br x , FA 0.85 MA 0.15 PbI 2.55 Br 0.45 , Cs 0.1 FA 0.75 MA 0.15 PbI 2.49 Br 0.51 ). In this paper, we review the recent progress on the synthesis and fundamental aspects of mixed cation and halide perovskites correlating with device performance, long-term stability, and hysteresis. In the outlook, we outline the future research directions based on the reported results as well as related topics that warrant further investigation.

  7. Lead Halide Perovskite Photovoltaic as a Model p-i-n Diode.

    Science.gov (United States)

    Miyano, Kenjiro; Tripathi, Neeti; Yanagida, Masatoshi; Shirai, Yasuhiro

    2016-02-16

    The lead halide perovskite photovoltaic cells, especially the iodide compound CH3NH3PbI3 family, exhibited enormous progress in the energy conversion efficiency in the past few years. Although the first attempt to use the perovskite was as a sensitizer in a dye-sensitized solar cell, it has been recognized at the early stage of the development that the working of the perovskite photovoltaics is akin to that of the inorganic thin film solar cells. In fact, theoretically perovskite is always treated as an ordinary direct band gap semiconductor and hence the perovskite photovoltaics as a p-i-n diode. Despite this recognition, research effort along this line of thought is still in pieces and incomplete. Different measurements have been applied to different types of devices (different not only in the materials but also in the cell structures), making it difficult to have a coherent picture. To make the situation worse, the perovskite photovoltaics have been plagued by the irreproducible optoelectronic properties, most notably the sweep direction dependent current-voltage relationship, the hysteresis problem. Under such circumstances, it is naturally very difficult to analyze the data. Therefore, we set out to make hysteresis-free samples and apply time-tested models and numerical tools developed in the field of inorganic semiconductors. A series of electrical measurements have been performed on one type of CH3NH3PbI3 photovoltaic cells, in which a special attention was paid to ensure that their electronic reproducibility was better than the fitting error in the numerical analysis. The data can be quantitatively explained in terms of the established models of inorganic semiconductors: current/voltage relationship can be very well described by a two-diode model, while impedance spectroscopy revealed the presence of a thick intrinsic layer with the help of a numerical solver, SCAPS, developed for thin film solar cell analysis. These results point to that CH3NH3PbI3 is an

  8. Topological Crystalline Insulators and Dirac Octets in Anti-perovskites

    OpenAIRE

    Hsieh, Timothy H.; Liu, Junwei; Fu, Liang

    2014-01-01

    We predict a new class of topological crystalline insulators (TCI) in the anti-perovskite material family with the chemical formula A$_3$BX. Here the nontrivial topology arises from band inversion between two $J=3/2$ quartets, which is described by a generalized Dirac equation for a "Dirac octet". Our work suggests that anti-perovskites are a promising new venue for exploring the cooperative interplay between band topology, crystal symmetry and electron correlation.

  9. High Photoluminescence Quantum Yields in Organic Semiconductor-Perovskite Composite Thin Films.

    Science.gov (United States)

    Longo, Giulia; La-Placa, Maria-Grazia; Sessolo, Michele; Bolink, Henk J

    2017-10-09

    One of the obstacles towards efficient radiative recombination in hybrid perovskites is a low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron-donor additives can lead to a substantial reduction of the non-radiative recombination in perovskite films. Herein, the approach using small molecules with semiconducting properties, which are candidates to be implemented in future optoelectronic devices, is presented. In particular, highly luminescent perovskite-organic semiconductor composite thin films have been developed, which can be processed from solution in a simple coating step. By tuning the relative concentration of methylammonium lead bromide (MAPbBr 3 ) and 9,9spirobifluoren-2-yl-diphenyl-phosphine oxide (SPPO1), it is possible to achieve photoluminescent quantum yields (PLQYs) as high as 85 %. This is attributed to the dual functions of SPPO1 that limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where charge injection and transport was found to be severely hindered for the perovskite/SPPO1 material. This was alleviated by partially substituting SPPO1 with a hole-transporting material, 1,3-bis(N-carbazolyl)benzene (mCP), leading to bright electroluminescence. The potential of combining perovskite and organic semiconductors to prepare materials with improved properties opens new avenues for the preparation of simple lightemitting devices using perovskites as the emitter. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Facile Synthesis of CeO2-LaFeO3 Perovskite Composite and Its Application for 4-(Methylnitrosamino-1-(3-Pyridyl-1-Butanone (NNK Degradation

    Directory of Open Access Journals (Sweden)

    Kaixuan Wang

    2016-04-01

    Full Text Available A facile and environmentally friendly surface-ion adsorption method using CeCO3OH@C as template was demonstrated to synthesize CeO2-LaFeO3 perovskite composite material. The obtained composite was characterized by X-ray diffraction (XRD, fourier transform infrared spectra (FT-IR, field-emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, thermo-gravimetric analysis and differential scanning calorimetry (TG-DSC, N2 adsorption/desorption isotherms and X-ray photoelectron spectra (XPS measurements. The catalytic degradation of nitrosamine 4-(methylnitrosamino-1-(3-pyridyl-1-butanone (NNK was tested to evaluate catalytic activity of the CeO2-LaFeO3 composite. Much better activity was observed for the CeO2-LaFeO3 composite comparing with CeO2 and LaFeO3. These results suggested that perovskite composite materials are a promising candidate for the degradation of tobacco-specific nitrosamines (TSNAs.

  11. Non-collinear magnetism in multiferroic perovskites.

    Science.gov (United States)

    Bousquet, Eric; Cano, Andrés

    2016-03-31

    We present an overview of the current interest in non-collinear magnetism in multiferroic perovskite crystals. We first describe the different microscopic mechanisms giving rise to the non-collinearity of spins in this class of materials. We discuss, in particular, the interplay between non-collinear magnetism and ferroelectric and antiferrodistortive distortions of the perovskite structure, and how this can promote magnetoelectric responses. We then provide a literature survey on non-collinear multiferroic perovskites. We discuss numerous examples of spin cantings driving weak ferromagnetism in transition metal perovskites, and of spin-induced ferroelectricity as observed in the rare-earth based perovskites. These examples are chosen to best illustrate the fundamental role of non-collinear magnetism in the design of multiferroicity.

  12. Residual tensile stresses and piezoelectric properties in BiFeO3-Bi(Zn1/2Ti1/2O3-PbTiO3 ternary solid solution perovskite ceramics

    Directory of Open Access Journals (Sweden)

    Weilin Zheng

    2016-08-01

    Full Text Available For low dielectric loss perovskite-structured (1-x-yBiFeO3-xBi(Zn1/2Ti1/2O3-yPbTiO3 (BF-BZT-PT (x = 0.04-0.15 and y = 0.15-0.26 ceramics in rhombohedral/tetragonal coexistent phase, structural phase transitions were studied using differential thermal analyzer combined with temperature-dependent dielectric measurement. Two lattice structural phase transitions are disclosed in various BF-BZT-PT perovskites, which is different from its membership of BiFeO3 exhibiting just one lattice structural phase transition at Curie temperature TC= 830oC. Consequently, residual internal tensile stresses were revealed experimentally through XRD measurements on ceramic pellets and counterpart powders, which are reasonably attributed to special structural phase transition sequence of BF-BZT-PT solid solution perovskites. Low piezoresponse was observed and argued extrinsically resulting from residual tensile stresses pinning ferroelectric polarization switching. Post-annealing and subsequent quenching was found effective for eliminating residual internal stresses in those BZT-less ceramics, and good piezoelectric property of d33 ≥ 28 pC/N obtained for 0.70BF-0.08BZT-0.22PT and 0.05 wt% MnO2-doped 0.70BF-0.04BZT-0.26PT ceramics with TC ≥ 640oC, while it seemed no effective for those BZT-rich BF-BZT-PT ceramics with x = 0.14 and 0.15 studied here.

  13. Observation of Quantum Confinement in Monodisperse Methylammonium Lead Halide Perovskite Nanocrystals Embedded in Mesoporous Silica.

    Science.gov (United States)

    Malgras, Victor; Tominaka, Satoshi; Ryan, James W; Henzie, Joel; Takei, Toshiaki; Ohara, Koji; Yamauchi, Yusuke

    2016-10-13

    Hybrid organic-inorganic metal halide perovskites have fascinating electronic properties and have already been implemented in various devices. Although the behavior of bulk metal halide perovskites has been widely studied, the properties of perovskite nanocrystals are less well-understood because synthesizing them is still very challenging, in part because of stability. Here we demonstrate a simple and versatile method to grow monodisperse CH 3 NH 3 PbBr x I x-3 perovskite nanocrystals inside mesoporous silica templates. The size of the nanocrystal is governed by the pore size of the templates (3.3, 3.7, 4.2, 6.2, and 7.1 nm). In-depth structural analysis shows that the nanocrystals maintain the perovskite crystal structure, but it is slightly distorted. Quantum confinement was observed by tuning the size of the particles via the template. This approach provides an additional route to tune the optical bandgap of the nanocrystal. The level of quantum confinement was modeled taking into account the dimensions of the rod-shaped nanocrystals and their close packing inside the channels of the template. Photoluminescence measurements on CH 3 NH 3 PbBr clearly show a shift from green to blue as the pore size is decreased. Synthesizing perovskite nanostructures in templates improves their stability and enables tunable electronic properties via quantum confinement. These structures may be useful as reference materials for comparison with other perovskites, or as functional materials in all solid-state light-emitting diodes.

  14. Magnetic structure of post-perovskite compound CaIrO3

    International Nuclear Information System (INIS)

    Ohgushi, Kenya; Ohsumi, Hiroyuki; Yamaura, Jun-ichi; Arima, Taka-hisa

    2014-01-01

    We have performed resonant X-ray diffraction experiments at the Ir L absorption edges for a post-perovskite compound CaIrO 3 with a Ir 4+ : (t 2g ) 5 electronic configuration. By observing the magnetic signals, we could clearly see that the magnetic structure was a striped ordering with antiferromagnetic moments along the c axis and that the wave function of a t 2g hole is strongly spin-orbit entangled, the J eff = 1/2 state. The observed spin arrangement is consistent with a theoretical work predicting a unique superexchange interaction called the quantum compass model. Our studies stimulate further studies for developing novel quantum states in iridium oxides. (author)

  15. Cation-induced band-gap tuning in organohalide perovskites: interplay of spin-orbit coupling and octahedra tilting.

    Science.gov (United States)

    Amat, Anna; Mosconi, Edoardo; Ronca, Enrico; Quarti, Claudio; Umari, Paolo; Nazeeruddin, Md K; Grätzel, Michael; De Angelis, Filippo

    2014-06-11

    Organohalide lead perovskites have revolutionized the scenario of emerging photovoltaic technologies. The prototype MAPbI3 perovskite (MA = CH3NH3(+)) has dominated the field, despite only harvesting photons above 750 nm (∼1.6 eV). Intensive research efforts are being devoted to find new perovskites with red-shifted absorption onset, along with good charge transport properties. Recently, a new perovskite based on the formamidinium cation ((NH2)2CH(+) = FA) has shown potentially superior properties in terms of band gap and charge transport compared to MAPbI3. The results have been interpreted in terms of the cation size, with the larger FA cation expectedly delivering reduced band-gaps in Pb-based perovskites. To provide a full understanding of the interplay among size, structure, and organic/inorganic interactions in determining the properties of APbI3 perovskites, in view of designing new materials and fully exploiting them for solar cells applications, we report a fully first-principles investigation on APbI3 perovskites with A = Cs(+), MA, and FA. Our results evidence that the tetragonal-to-quasi cubic structural evolution observed when moving from MA to FA is due to the interplay of size effects and enhanced hydrogen bonding between the FA cations and the inorganic matrix altering the covalent/ionic character of Pb-I bonds. Most notably, the observed cation-induced structural variability promotes markedly different electronic and optical properties in the MAPbI3 and FAPbI3 perovskites, mediated by the different spin-orbit coupling, leading to improved charge transport and red-shifted absorption in FAPbI3 and in general in pseudocubic structures. Our theoretical model constitutes the basis for the rationale design of new and more efficient organohalide perovskites for solar cells applications.

  16. Morphological Control for High Performance, Solution-Processed Planar Heterojunction Perovskite Solar Cells

    KAUST Repository

    Eperon, Giles E.

    2013-09-09

    Organometal trihalide perovskite based solar cells have exhibited the highest efficiencies to-date when incorporated into mesostructured composites. However, thin solid films of a perovskite absorber should be capable of operating at the highest efficiency in a simple planar heterojunction configuration. Here, it is shown that film morphology is a critical issue in planar heterojunction CH3NH3PbI3-xCl x solar cells. The morphology is carefully controlled by varying processing conditions, and it is demonstrated that the highest photocurrents are attainable only with the highest perovskite surface coverages. With optimized solution based film formation, power conversion efficiencies of up to 11.4% are achieved, the first report of efficiencies above 10% in fully thin-film solution processed perovskite solar cells with no mesoporous layer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. New W-and Mo-containing perovskites sythesized at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sevast' yanova, L G; Burdina, K P; Zubova, E V; Venevtsev, Yu N [Moskovskij Gosudarstvennyj Univ. (USSR); Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR))

    1979-11-01

    The possibility of synthesizing complex oxide W and Mo-containing compounds having a perovskite structure is shown. The optimum synthesis conditions have been defined. Critical pressure Psub(cr) has been found to equal 70 kbar, above which the perovskite structure can still exist at room temperature. The ''pressure-temperature'' diagram was used to define the stability region of perovskite of Pb(HgMo)sub(1/2)Osub(3)composition, bound by pressure p=35 to 50 kbar and a temperature of 700 deg C.

  18. Perovskite Solar Cells: Progress and Advancements

    Directory of Open Access Journals (Sweden)

    Naveen Kumar Elumalai

    2016-10-01

    Full Text Available Organic–inorganic hybrid perovskite solar cells (PSCs have emerged as a new class of optoelectronic semiconductors that revolutionized the photovoltaic research in the recent years. The perovskite solar cells present numerous advantages include unique electronic structure, bandgap tunability, superior charge transport properties, facile processing, and low cost. Perovskite solar cells have demonstrated unprecedented progress in efficiency and its architecture evolved over the period of the last 5–6 years, achieving a high power conversion efficiency of about 22% in 2016, serving as a promising candidate with the potential to replace the existing commercial PV technologies. This review discusses the progress of perovskite solar cells focusing on aspects such as superior electronic properties and unique features of halide perovskite materials compared to that of conventional light absorbing semiconductors. The review also presents a brief overview of device architectures, fabrication methods, and interface engineering of perovskite solar cells. The last part of the review elaborates on the major challenges such as hysteresis and stability issues in perovskite solar cells that serve as a bottleneck for successful commercialization of this promising PV technology.

  19. Development of Perovskite-Type Materials for Thermoelectric Application

    Directory of Open Access Journals (Sweden)

    Tingjun Wu

    2018-06-01

    Full Text Available Oxide perovskite materials have a long history of being investigated for thermoelectric applications. Compared to the state-of-the-art tin and lead chalcogenides, these perovskite compounds have advantages of low toxicity, eco-friendliness, and high elemental abundance. However, because of low electrical conductivity and high thermal conductivity, the total thermoelectric performance of oxide perovskites is relatively poor. Variety of methods were used to enhance the TE properties of oxide perovskite materials, such as doping, inducing oxygen vacancy, embedding crystal imperfection, and so on. Recently, hybrid perovskite materials started to draw attention for thermoelectric application. Due to the low thermal conductivity and high Seebeck coefficient feature of hybrid perovskites materials, they can be promising thermoelectric materials and hold the potential for the application of wearable energy generators and cooling devices. This mini-review will build a bridge between oxide perovskites and burgeoning hybrid halide perovskites in the research of thermoelectric properties with an aim to further enhance the relevant performance of perovskite-type materials.

  20. Ambipolar solution-processed hybrid perovskite phototransistors

    KAUST Repository

    Li, Feng

    2015-09-08

    Organolead halide perovskites have attracted substantial attention because of their excellent physical properties, which enable them to serve as the active material in emerging hybrid solid-state solar cells. Here we investigate the phototransistors based on hybrid perovskite films and provide direct evidence for their superior carrier transport property with ambipolar characteristics. The field-effect mobilities for triiodide perovskites at room temperature are measured as 0.18 (0.17) cm2 V−1 s−1 for holes (electrons), which increase to 1.24 (1.01) cm2 V−1 s−1 for mixed-halide perovskites. The photoresponsivity of our hybrid perovskite devices reaches 320 A W−1, which is among the largest values reported for phototransistors. Importantly, the phototransistors exhibit an ultrafast photoresponse speed of less than 10 μs. The solution-based process and excellent device performance strongly underscore hybrid perovskites as promising material candidates for photoelectronic applications.

  1. Structural characterization and optical properties of perovskite ZnZrO 3 nanoparticles

    KAUST Repository

    Zhu, Xinhua

    2014-03-17

    Perovskite ZnZrO3 nanoparticles were synthesized by hydrothermal method, and their microstructures and optical properties were characterized. The crystallinity, phase formation, morphology and composition of the as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED), high-resolutiontransmission electron microscopy (HRTEM), and energy-dispersive X-ray (EDX) spectroscopy analysis, respectively. TEM images demonstrated that the average particle size of the ZnZrO3 powders was increased with increasing the Zn/Zr molar ratios in the precursors, and more large ZnZrO3 particles with cubic morphology were observed at high Zn/Zr molar ratios. In addition, the phase structures of the ZnZrO3 particles were also evolved from a cubic to tetragonal perovskite phase, as revealed by XRD and SAED patterns. HRTEM images demonstrate that surface structures of the ZnZrO3 powders synthesized at high Zn/Zr molar ratios, are composed of corners bound by the {100} mini-facets, and the surface steps lying on the {100} planes are frequently observed, whereas the (101) facet isoccasionally observed. The formation of such a rough surface structure is understood from the periodic bond chain theory. Quantitative EDX analyses demonstrated that the atomic concentrations (at.%) of Zn:Zr:O in the particles were 20.70:21.07:58.23, as close to the composition of ZnZrO3. In the optical spectra, a significant red shift of the absorption edges (for the ZnZrO3 nanopowders) from UV to visible region (from 394 to 417 nm) was observed as increasing the Zn/Zr molar ratios in the precursors, which corresponds to that the band gap energies of the ZnZrO3 nanopowders can be continuously tuned from 3.15 to 2.97 eV. This opens an easy way to tune the band gap energies of the ZnZrO3 nanopowders. © 2014 The American Ceramic Society.

  2. Displacement-type ferroelectric transition with magnetic Mn ions in perovskite Sr1-xBaxMnO3

    Science.gov (United States)

    Sakai, Hideaki; Fujioka, Jun; Fukuda, Tatsuo; Okuyama, Daisuke; Hashizume, Daisuke; Kagawa, Fumitaka; Nakao, Hironori; Murakami, Youich; Arima, Takahisa; Baron, Alfred Q. R.; Taguchi, Yasujiro; Tokura, Yoshinori

    2012-02-01

    Almost all the proper ferroelectrics with a perovskite structure discovered so far have no d-electrons in the off-center transition metal site, as exemplified by BaTiO3 and Pb(Zr,Ti)O3. This empirical d^0 rule is incompatible with the emergence of magnetism and has significantly restricted the variety of multiferroic materials. In this work, we have discovered a displacement-type ferroelectric transition originating from off-center Mn^4+ ions in antiferromagnetic Mott insulators Sr1-xBaxMnO3. As Ba concentration increases, the perovskite lattice shows the typical soft mode dynamics, and the ferroelectricity shows up for x .45. In addition to the large polarization and high transition temperature comparable to BaTiO3, we demonstrate that the magnetic order suppresses the ferroelectric lattice dilation by ˜70% and increases the soft-phonon energy by ˜50%, indicating gigantic magnetoelectric effects [1]. This work was supported by the FIRST program on ``Quantum Science on Strong Correlation''. [4pt] [1] H. Sakai et al., Phys. Rev. Lett. 107, 137601 (2011).

  3. Working Mechanism for Flexible Perovskite Solar Cells with Simplified Architecture.

    Science.gov (United States)

    Xu, Xiaobao; Chen, Qi; Hong, Ziruo; Zhou, Huanping; Liu, Zonghao; Chang, Wei-Hsuan; Sun, Pengyu; Chen, Huajun; De Marco, Nicholas; Wang, Mingkui; Yang, Yang

    2015-10-14

    In this communication, we report an efficient and flexible perovskite solar cell based on formamidinium lead trihalide (FAPbI3) with simplified configuration. The device achieved a champion efficiency of 12.70%, utilizing direct contact between metallic indium tin oxide (ITO) electrode and perovskite absorber. The underlying working mechanism is proposed subsequently, via a systematic investigation focusing on the heterojunction within this device. A significant charge storage has been observed in the perovskite, which is believed to generate photovoltage and serves as the driving force for charge transferring from the absorber to ITO electrode as well. More importantly, this simplified device structure on flexible substrates suggests its compatibility for scale-up fabrication, which paves the way for commercialization of perovskite photovoltaic technology.

  4. Role of organic cations on hybrid halide perovskite CH3NH3PbI3 surfaces

    Science.gov (United States)

    Teng, Qiang; Shi, Ting-Ting; Tian, Ren-Yu; Yang, Xiao-Bao; Zhao, Yu-Jun

    2018-02-01

    Organic-inorganic hybrid halide perovskite CH3NH3PbI3 (MAPbI3) has received rapid progress in power conversion efficiency as promising photovoltaic materials, yet the surface structures and the role of MA cations are not well understood. In this work, we investigated the structural stability and electronic properties of (001) surface of cubic, (001) and (110) surfaces of tetragonal and orthorhombic phases of MAPbI3 with considering the orientation of MA cations, by density functional theory calculations. We demonstrate that the orientation of MA cations has profound consequences on the structural stability and the electronic properties of the surfaces, in contrast to the bulk phases. Compared with the MA-I terminated surfaces, the Pb-I2 terminated ones generally have smaller band gaps and the advantage to enable the photo-excited holes to transfer to the hole-transport materials in both tetragonal and orthorhombic phases. Overall, we suggest that the films with Pb-I2 terminated surfaces would prevail in high performance solar energy absorbers.

  5. Fabrication of organic-inorganic perovskite thin films for planar solar cells via pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yangang; Zhang, Xiaohang; Gong, Yunhui; Shin, Jongmoon; Wachsman, Eric D.; Takeuchi, Ichiro, E-mail: takeuchi@umd.edu [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20740 (United States); Yao, Yangyi; Hsu, Wei-Lun; Dagenais, Mario [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20740 (United States)

    2016-01-15

    We report on fabrication of organic-inorganic perovskite thin films using a hybrid method consisting of pulsed laser deposition (PLD) of lead iodide and spin-coating of methylammonium iodide. Smooth and highly crystalline CH{sub 3}NH{sub 3}PbI{sub 3} thin films have been fabricated on silicon and glass coated substrates with fluorine doped tin oxide using this PLD-based hybrid method. Planar perovskite solar cells with an inverted structure have been successfully fabricated using the perovskite films. Because of its versatility, the PLD-based hybrid fabrication method not only provides an easy and precise control of the thickness of the perovskite thin films, but also offers a straightforward platform for studying the potential feasibility in using other metal halides and organic salts for formation of the organic-inorganic perovskite structure.

  6. Fabrication of organic-inorganic perovskite thin films for planar solar cells via pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    Yangang Liang

    2016-01-01

    Full Text Available We report on fabrication of organic-inorganic perovskite thin films using a hybrid method consisting of pulsed laser deposition (PLD of lead iodide and spin-coating of methylammonium iodide. Smooth and highly crystalline CH3NH3PbI3 thin films have been fabricated on silicon and glass coated substrates with fluorine doped tin oxide using this PLD-based hybrid method. Planar perovskite solar cells with an inverted structure have been successfully fabricated using the perovskite films. Because of its versatility, the PLD-based hybrid fabrication method not only provides an easy and precise control of the thickness of the perovskite thin films, but also offers a straightforward platform for studying the potential feasibility in using other metal halides and organic salts for formation of the organic-inorganic perovskite structure.

  7. Layer-by-layer deposition of nanostructured CsPbBr3 perovskite thin films

    Science.gov (United States)

    Reshetnikova, A. A.; Matyushkin, L. B.; Andronov, A. A.; Sokolov, V. S.; Aleksandrova, O. A.; Moshnikov, V. A.

    2017-11-01

    Layer-by-layer deposition of nanostructured perovskites cesium lead halide thin films is described. The method of deposition is based on alternate immersion of the substrate in the precursor solutions or colloidal solution of nanocrystals and methyl acetate/lead nitrate solution using the device for deposition of films by SILAR and dip-coating techniques. An example of obtaining a photosensitive structure based on nanostructures of ZnO nanowires and layers of CsBbBr3 nanocrystals is also shown.

  8. Highly Controlled Codeposition Rate of Organolead Halide Perovskite by Laser Evaporation Method.

    Science.gov (United States)

    Miyadera, Tetsuhiko; Sugita, Takeshi; Tampo, Hitoshi; Matsubara, Koji; Chikamatsu, Masayuki

    2016-10-05

    Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH 3 NH 3 I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI 2 and CH 3 NH 3 I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

  9. Vapor Phase Synthesis of Organometal Halide Perovskite Nanowires for Tunable Room-Temperature Nanolasers.

    Science.gov (United States)

    Xing, Jun; Liu, Xin Feng; Zhang, Qing; Ha, Son Tung; Yuan, Yan Wen; Shen, Chao; Sum, Tze Chien; Xiong, Qihua

    2015-07-08

    Semiconductor nanowires have received considerable attention in the past decade driven by both unprecedented physics derived from the quantum size effect and strong isotropy and advanced applications as potential building blocks for nanoscale electronics and optoelectronic devices. Recently, organic-inorganic hybrid perovskites have been shown to exhibit high optical absorption coefficient, optimal direct band gap, and long electron/hole diffusion lengths, leading to high-performance photovoltaic devices. Herein, we present the vapor phase synthesis free-standing CH3NH3PbI3, CH3NH3PbBr3, and CH3NH3PbIxCl3(-x) perovskite nanowires with high crystallinity. These rectangular cross-sectional perovskite nanowires have good optical properties and long electron hole diffusion length, which ensure adequate gain and efficient optical feedback. Indeed, we have demonstrated optical-pumped room-temperature CH3NH3PbI3 nanowire lasers with near-infrared wavelength of 777 nm, low threshold of 11 μJ/cm(2), and a quality factor as high as 405. Our research advocates the promise of optoelectronic devices based on organic-inorganic perovskite nanowires.

  10. Crystal structure and magnetoresistance of La0.7Ca0.3MnO3 perovskite at room temperature

    International Nuclear Information System (INIS)

    Engkir Sukirman; Wisnu Ari Adi; Yustinus Purwamargapratala

    2012-01-01

    A comparative study on crystal structure and magnetoresistance (MR) of La 0.7 Ca 0.3 MnO 3 (LCMO) perovskite toward LaMnO 3 (LMO) and CaMnO 3 (CMO) parent compounds have been carried out to study the change of LCMO due to magnetic fields variations at room temperature. The LCMO, LMO and CMO were synthesized using high energy milling (HEM) method. The precursors obtained were pressed into pellet and sintered at T s = 1350°C for 6 hours. The qualitative analysis were conducted by x-rays diffraction technique using Rietveld method. The MR effect on the samples were measured using four point probe (FPP) method and the surface structure of pellets were observed by scanning electron microscope (SEM). The samples have the same crystal structure, namely orthorhombic, space group: Pnma, No. 62. The lattice parameters of LCMO were successfully confirmed until four decimal precision, namely a = 5.4851(3) Å, b = 7.7601(4) Å, c = 5.5185(2) Å. The lattice parameters for LMO and CMO successively are a = 5.4405(9) Å, b = 7.717(1) Å, c = 5.537(1) Å and a = 5.2973(6) Å, b = 7.477(1) Å, c = 5.281 (1) Å. All samples have grain diameter of around 1,000 nm with a globule like form and every grain consists of 27 crystallites. The MR for LCMO, LMO and CMO samples at room temperature are -10.1; -7.3 dan -12.3%, respectively, and comparable with the one of multilayers based GMR [Cu/NiFeCo] x10 /Ta. The LCMO perovskite bulk can be used to detect the magnetic microbeads and ferrofluid. (author)

  11. Organic-Inorganic Hybrid Interfacial Layer for High-Performance Planar Perovskite Solar Cells.

    Science.gov (United States)

    Yang, Hao; Cong, Shan; Lou, Yanhui; Han, Liang; Zhao, Jie; Sun, Yinghui; Zou, Guifu

    2017-09-20

    4,7-Diphenyl-1,10-phenanthroline (Bphen) is an efficient electron transport and hole blocking material in organic photoelectric devices. Here, we report cesium carbonate (Cs 2 CO 3 ) doped Bphen as cathode interfacial layer in CH 3 NH 3 PbI 3-x Cl x based planar perovskite solar cells (PSCs). Investigation finds that introducing Cs 2 CO 3 suppresses the crystallization of Bphen and benefits a smooth interface contact between the perovskite and electrode, resulting in the decrease in carrier recombination and the perovskite degradation. In addition, the matching energy level of Bphen film in the PSCs effectively blocks the holes diffusion to cathode. The resultant power conversion efficiency (PCE) achieves as high as 17.03% in comparison with 12.67% of reference device without doping. Besides, experiments also demonstrate the stability of PSCs have large improvement because the suppressed crystallization of Bphen by doping Cs 2 CO 3 as a superior barrier layer blocks the Ag atom and surrounding moisture access to the vulnerable perovskite layer.

  12. Band gap and mobility of epitaxial perovskite BaSn1 -xHfxO3 thin films

    Science.gov (United States)

    Shin, Juyeon; Lim, Jinyoung; Ha, Taewoo; Kim, Young Mo; Park, Chulkwon; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

    2018-02-01

    A wide band-gap perovskite oxide BaSn O3 is attracting much attention due to its high electron mobility and oxygen stability. On the other hand, BaHf O3 was recently reported to be an effective high-k gate oxide. Here, we investigate the band gap and mobility of solid solutions of BaS n1 -xH fxO3 (x =0 -1 ) (BSHO) as a basis to build advanced perovskite oxide heterostructures. All the films were epitaxially grown on MgO substrates using pulsed laser deposition. Density functional theory calculations confirmed that Hf substitution does not create midgap states while increasing the band gap. From x-ray diffraction and optical transmittance measurements, the lattice constants and the band-gap values are significantly modified by Hf substitution. We also measured the transport properties of n -type La-doped BSHO films [(Ba ,La ) (Sn ,Hf ) O3 ] , investigating the feasibility of modulation doping in the BaSn O3/BSHO heterostructures. The Hall measurement data revealed that, as the Hf content increases, the activation rate of the La dopant decreases and the scattering rate of the electrons sharply increases. These properties of BSHO films may be useful for applications in various heterostructures based on the BaSn O3 system.

  13. Shape-Controlled Synthesis of All-Inorganic CsPbBr3 Perovskite Nanocrystals with Bright Blue Emission.

    Science.gov (United States)

    Liang, Zhiqin; Zhao, Suling; Xu, Zheng; Qiao, Bo; Song, Pengjie; Gao, Di; Xu, Xurong

    2016-10-26

    We developed a colloidal synthesis of CsPbBr 3 perovskite nanocrystals (NCs) at a relative low temperature (90 °C) for the bright blue emission which differs from the original green emission (∼510 nm) of CsPbBr 3 nanocubes as reported previously. Shapes of the obtained CsPbBr 3 NCs can be systematically engineered into single and lamellar-structured 0D quantum dots, as well as face-to-face stacking 2D nanoplatelets and flat-lying 2D nanosheets via tuning the amounts of oleic acid (OA) and oleylamine (OM). They exhibit sharp excitonic PL emissions at 453, 472, 449, and 452 nm, respectively. The large blue shift relative to the emission of CsPbBr 3 bulk crystal can be ascribed to the strong quantum confinement effects of these various nanoshapes. PL decay lifetimes are measured, ranging from several to tens of nanoseconds, which infers the higher ratio of exciton radiative recombination to the nonradiative trappers in the obtained CsPbBr 3 NCs. These shape-controlled CsPbBr 3 perovskite NCs with the bright blue emission will be widely used in optoelectronic applications, especially in blue LEDs which still lag behind compared to the better developed red and green LEDs.

  14. Characterization and carbon monoxide oxidation activity of La1-ySryCr1-xRuxO3 perovskites

    Directory of Open Access Journals (Sweden)

    C. MARINOVA

    2000-01-01

    Full Text Available The oxidation of CO over La1-ySryCr1-xRuxO3 perovskite type oxides with y=0.3 and 0 £ x £ 0.100 have been studied. X-ray fluorescence analysis confirmed that content of elements in the bulk corresponds to the established nominal perovskite stoichiometry, indicating that no significant oxidation of ruthenium into volatile polyvalent oxides with their consequented escape from the sample occurred in air up to the temperature of 1000°C. According to X-ray diffraction analysis, all sampls achieved the perovskite hexagonal with the presence of some SrCrO4. X-ray photoelectron spectroscopy analysis of ruthenium samples shows higher Ru and Sr surface concentraitions than in the bulk. The binding energy for Ru3p is virtually the same in all samples and consistent with that of Ru4+ (463.6-464.3eV. Kinetic studies were performed in a differential recycle reactor with a recycling ratio 80. The results show that substitution of Ru4+ for Cr3+ in La1-ySryCrO3 leads to a significant increase in both the activity and the activation energy. The global CO oxidation rate, referred on the BET surface area, correlates with the surface Ru4+ atomic concentraiton. Hence, the activity reflect the surface enrichment in ruthenium. Moreover, an identical apparent activation energy E = 93 kJ/mol and the same specific rate per ruthenium surface ion were obtained for samples with a Ru content x ³ 0.05 suggest that exposed Ru4+ ions mainly participate in the reaction.

  15. High-temperature compressive creep behaviour of perovskite-type oxides SrTi1-xFexO3

    NARCIS (Netherlands)

    ten Donkelaar, S.F.P.; Stournari, V.; Malzbender, J.; Nijmeijer, Arian; Bouwmeester, Henricus J.M.

    2015-01-01

    Compressive creep tests have been performed on mixed ionic-electronic conducting perovskite-type oxides SrTi1-xFexO3- (STF, x = 0.3, 0.5 and 0.7). Observed activation energies and stress exponents, at 800–1000 ◦C and in the stress range 10 100 MPa, indicate that the steady-state creep rate of STF

  16. Structural relationships in rhombohedral perovskites with R-3C symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Bogush, A K; Pavlov, V I [AN Belorusskoj SSR, Minsk. Inst. Fiziki Tverdogo Tela i Poluprovodnikov

    1982-05-01

    In rhombohedral perovskites the structure parameters, e.g. the interaxial angle alpha/sub rh/ or the hexagonal lattice parameters a/sub H/ and c/sub H/ are completely determined by the tilt angle omega. The geometrical relations between these structural parameters and the tilt angle omega are reported.

  17. Observation of Internal Photoinduced Electron and Hole Separation in Hybrid Two-Dimentional Perovskite Films.

    Science.gov (United States)

    Liu, Junxue; Leng, Jing; Wu, Kaifeng; Zhang, Jun; Jin, Shengye

    2017-02-01

    Two-dimensional (2D) organolead halide perovskites are promising for various optoelectronic applications. Here we report a unique spontaneous charge (electron/hole) separation property in multilayered (BA) 2 (MA) n-1 Pb n I 3n+1 (BA = CH 3 (CH 2 ) 3 NH 3 + , MA = CH 3 NH 3 + ) 2D perovskite films by studying the charge carrier dynamics using ultrafast transient absorption and photoluminescence spectroscopy. Surprisingly, the 2D perovskite films, although nominally prepared as "n = 4", are found to be mixture of multiple perovskite phases, with n = 2, 3, 4 and ≈ ∞, that naturally align in the order of n along the direction perpendicular to the substrate. Driven by the band alignment between 2D perovskites phases, we observe consecutive photoinduced electron transfer from small-n to large-n phases and hole transfer in the opposite direction on hundreds of picoseconds inside the 2D film of ∼358 nm thickness. This internal charge transfer efficiently separates electrons and holes to the upper and bottom surfaces of the films, which is a unique property beneficial for applications in photovoltaics and other optoelectronics devices.

  18. Decarbonization process for carbothermically produced aluminum

    Science.gov (United States)

    Bruno, Marshall J.; Carkin, Gerald E.; DeYoung, David H.; Dunlap, Sr., Ronald M.

    2015-06-30

    A method of recovering aluminum is provided. An alloy melt having Al.sub.4C.sub.3 and aluminum is provided. This mixture is cooled and then a sufficient amount of a finely dispersed gas is added to the alloy melt at a temperature of about 700.degree. C. to about 900.degree. C. The aluminum recovered is a decarbonized carbothermically produced aluminum where the step of adding a sufficient amount of the finely dispersed gas effects separation of the aluminum from the Al.sub.4C.sub.3 precipitates by flotation, resulting in two phases with the Al.sub.4C.sub.3 precipitates being the upper layer and the decarbonized aluminum being the lower layer. The aluminum is then recovered from the Al.sub.4C.sub.3 precipitates through decanting.

  19. Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Bazuev, G V; Makarova, O V; Shvejkin, G P [AN SSSR, Sverdlovsk. Inst. Khimii

    1983-01-01

    A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln/sup 3 +/ cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm/sup 3/ size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balance with electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti/sup 3 +/ cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled ..pi..*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility.

  20. ZnO nanostructures as electron extraction layers for hybrid perovskite thin films

    Science.gov (United States)

    Nikolaidou, Katerina; Sarang, Som; Tung, Vincent; Lu, Jennifer; Ghosh, Sayantani

    Optimum interaction between light harvesting media and electron transport layers is critical for the efficient operation of photovoltaic devices. In this work, ZnO layers of different morphologies are implemented as electron extraction and transport layers for hybrid perovskite CH3NH3PbI3 thin films. These include nanowires, nanoparticles, and single crystalline film. Charge transfer at the ZnO/perovskite interface is investigated and compared through ultra-fast characterization techniques, including temperature and power dependent spectroscopy, and time-resolved photoluminescence. The nanowires cause an enhancement in perovskite emission, which may be attributed to increased scattering and grain boundary formation. However, the ZnO layers with decreasing surface roughness exhibit better electron extraction, as inferred from photoluminescence quenching, reduction in the number of bound excitons, and reduced exciton lifetime in CH3NH3PbI3 samples. This systematic study is expected to provide an understanding of the fundamental processes occurring at the ZnO-CH3NH3PbI3 interface and ultimately, provide guidelines for the ideal configuration of ZnO-based hybrid Perovskite devices. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.