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Sample records for 111-oriented perovskite ferrate

  1. Electrical Transport Studies of (111)-Oriented BTO/LSMO-Based Heterostructures

    OpenAIRE

    2015-01-01

    Strain-induced magnetoelectric coupling in thin film heterostructures is a popular topic in the emerging field of multiferroic materials. Normally such heterostructures are grown with a (001) orientation, but (111)-oriented structures may exhibit in- creased coupling at the interfaces. In this study, the electrical transport properties of (111)-oriented ferroelectric-ferromagnetic BTO/LSMO heterostructures were in- vestigated in order to explore the possible effects of magnetoe...

  2. Ordered iodine adsorption as fingerprint of (111) orientation of Pt thin films

    Energy Technology Data Exchange (ETDEWEB)

    Braunschweig, Bjoern; Mitin, Alexej; Daum, Winfried [Institut fuer Physik und Physikalische Technologien, TU Clausthal, Leibnizstrasse 4, D-38678 Clausthal-Zellerfeld (Germany)

    2009-07-01

    Well-ordered Pt films deposited on re-usable substrates find applications such as inexpensive replacements for bulk single crystals or ultrathin transparent electrodes for spectro-electrochemical applications. While morphological properties of such films - roughness, atomic steps and spatial extent of atomically flat terraces - are easily imaged with the STM, atomic resolution of the Pt surface is often not attainable under environmental conditions. We demonstrate that the atomic surface structure of (111)-oriented Pt thin films deposited on {alpha}-Al{sub 2}O{sub 3}(0001) substrates is clearly revealed after adsorption of ordered iodine adlayers. In comparative STM studies with Pt thin films and with (111)-oriented bulk single crystals we observed the same coexisting (4 x 3{radical}(3)) and ({radical}(43) x {radical}(43)) iodine superstructures which indicates that our Pt films are highly ordered and (111)-oriented.

  3. Aluminum induced crystallization of strongly (111) oriented polycrystalline silicon thin film and nucleation analysis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A polycrystalline silicon thin film was fabricated on glass substrate by means of aluminum induced crystallization (AIC). Al and α-Si layers were deposited by magnetron sputtering respectively and annealed at 480°C for 1 h to realize layer exchange. The polycrystalline silicon thin film was continuous and strongly (111) oriented. By analyzing the structure variation of the oxidation membrane and lattice mismatch between γ-Al2O3 and Si, it was concluded that aluminum promoted the formation of (111) oriented silicon nucleus by controlling the orientation of γ-Al2O3, which was formed at the early stage of annealing.

  4. Potassium ferrate treatment of RFETS` contaminated groundwater

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-01-01

    The potassium ferrate treatment study of Rocky Flats Environmental Technology Site (RFETS) groundwater was performed under the Sitewide Treatability Studies Program (STSP). This study was undertaken to determine the effectiveness of potassium ferrate in a water treatment system to remove the contaminants of concern (COCS) from groundwater at the RFETS. Potassium ferrate is a simple salt where the iron is in the plus six valence state. It is the iron at the plus six valence state (Fe {sup +6}) that makes it an unique water treatment chemical, especially in waters where the pH is greater than seven. In basic solutions where the solubility of the oxides/hydroxides of many of the COCs is low, solids are formed as the pH is raised. By using ferrate these solids are agglomerated so they can be effectively removed by sedimentation in conventional water treatment equipment. The objective of this study was to determine the quality of water after treatment with potassium ferrate and to determine if the Colorado Water Quality Control Commission (CWQCC) discharge limits for the COCs listed in Table 1.0-1 could be met. Radionuclides in the groundwater were of special concern.

  5. Fabrication of (111)-oriented Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3}/SrTiO{sub 3} superlattices—A designed playground for honeycomb physics

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Daigorou [Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Matsuno, Jobu [RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan); Takagi, Hidenori [Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Max-Plank-Institute for solid state research, Heisenbergstrasse 1, Stuttgart 70569 (Germany)

    2015-04-01

    We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3} perovskite and two layers of SrTiO{sub 3} perovskite on SrTiO{sub 3}(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  6. Fabrication of (111-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices—A designed playground for honeycomb physics

    Directory of Open Access Journals (Sweden)

    Daigorou Hirai

    2015-04-01

    Full Text Available We report the fabrication of (111-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3 of Ca0.5Sr0.5IrO3 perovskite and two layers of SrTiO3 perovskite on SrTiO3(111 substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  7. Superconducting thin films of (100) and (111) oriented indium doped topological crystalline insulator SnTe

    Energy Technology Data Exchange (ETDEWEB)

    Si, Weidong, E-mail: wds@bnl.gov, E-mail: qiangli@bnl.gov; Zhang, Cheng; Wu, Lijun; Ozaki, Toshinori; Gu, Genda; Li, Qiang, E-mail: wds@bnl.gov, E-mail: qiangli@bnl.gov [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2015-08-31

    Recent discovery of the topological crystalline insulator SnTe has triggered a search for topological superconductors, which have potential application to topological quantum computing. The present work reports on the superconducting properties of indium doped SnTe thin films. The (100) and (111) oriented thin films were epitaxially grown by pulsed-laser deposition on (100) and (111) BaF{sub 2} crystalline substrates, respectively. The onset superconducting transition temperatures are about 3.8 K for (100) and 3.6 K for (111) orientations, slightly lower than that of the bulk. Magneto-resistive measurements indicate that these thin films may have upper critical fields higher than that of the bulk. With large surface-to-bulk ratio, superconducting indium doped SnTe thin films provide a rich platform for the study of topological superconductivity and potential device applications based on topological superconductors.

  8. Removal of Pharmaceutical residues by ferrate(VI.

    Directory of Open Access Journals (Sweden)

    Jia-Qian Jiang

    Full Text Available BACKGROUND: Pharmaceuticals and their metabolites are inevitably emitted into the waters. The adverse environmental and human health effects of pharmaceutical residues in water could take place under a very low concentration range; from several µg/L to ng/L. These are challenges to the global water industries as there is no unit process specifically designed to remove these pollutants. An efficient technology is thus sought to treat these pollutants in water and waste water. METHODOLOGY/MAJOR RESULTS: A novel chemical, ferrate, was assessed using a standard jar test procedure for the removal of pharmaceuticals. The analytical protocols of pharmaceuticals were standard solid phase extraction together with various instrumentation methods including LC-MS, HPLC-UV and UV/Vis spectroscopy. Ferrate can remove more than 80% of ciprofloxacin (CIP at ferrate dose of 1 mg Fe/L and 30% of ibuprofen (IBU at ferrate dose of 2 mg Fe/L. Removal of pharmaceuticals by ferrate was pH dependant and this was in coordinate to the chemical/physical properties of pharmaceuticals. Ferrate has shown higher capability in the degradation of CIP than IBU; this is because CIP has electron-rich organic moieties (EOM which can be readily degraded by ferrate oxidation and IBU has electron-withdrawing groups which has slow reaction rate with ferrate. Promising performance of ferrate in the treatment of real waste water effluent at both pH 6 and 8 and dose range of 1-5 mg Fe/L was observed. Removal efficiency of ciprofloxacin was the highest among the target compounds (63%, followed by naproxen (43%. On the other hand, n-acetyl sulphamethoxazole was the hardest to be removed by ferrate (8% only. CONCLUSIONS: Ferrate is a promising chemical to be used to treat pharmaceuticals in waste water. Adjusting operating conditions in terms of the properties of target pharmaceuticals can maximise the pharmaceutical removal efficiency.

  9. Induced effects of Cu underlayer on (111) orientation of Fe50 Mn50 thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; WANG Feng-ping; LIU Huan-ping; WU Ping; QIU Hong; PAN Li-qing

    2005-01-01

    Effects of Cu underlayer on the structure of Fe50 Mn50 films were studied. Samples with a structure of Fe50 Mn50 (200 nm)/Cu(tCu) were prepared by magnetron sputtering on thermally oxidized silicon substrates at room temperature. The thickness of Cu underlayer varied from 0 to 60 nm in the intervals of 10 nm. High-vacuum annealing treatments, at different temperatures of 200, 300 and 400 ℃ for 1 h, respectively, on the Fe50 Mn50 (200 nm)/Cu(20 nm) thin films were performed. The surface morphologies and textures of the samples were measured by field emission scan electronic microscope (FE-SEM) and X-ray diffraction(XRD). Energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy(AES) were used to analyze the compositional distribution. It is found that Cu underlayer has an obvious induce effect on (111) orientation of Fe50 Mn50 thin films. The induce effects of Cu on (111) orientation of Fe50 Mn50 changed with the increase of Cu layer thickness and the best effect was obtained at the Cu layer thickness of 20 nm. High-vacuum annealing treatments cause the migration of Mn atoms towards surface of the film and interface between Cu layer and substrate. With the increasing annealing temperature, migration of Mn atoms is more obvious, which leads to a Fe-riched Fe-Mn alloy film.

  10. Shape Memory Behavior of [111]-Oriented NiTi Single Crystals After Stress-Assisted Aging

    Institute of Scientific and Technical Information of China (English)

    Irfan Kaya; Hirobumi Tobe; Haluk Ersin Karaca; Emre Acar; Yuriy Chumlyakov

    2016-01-01

    The shape memory behavior of [111]-oriented NistTi49 (at.%) single crystals was investigated after stressassisted aging at 500 ℃ for 1.5 h under a compressive stress of-150 MPa.It was found that a single family of Ni4Ti3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress.Stressassisted aging resulted in tensile two-way shape memory effect strain of 1.56% under-5 MPa.Thermal cycling under -600 MPa resulted in a transformation strain of-2.15%,while the subsequent thermal cycling under-5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.

  11. Giant isothermal entropy change In (111)-oriented PMN-PT thin film

    Science.gov (United States)

    Hamad, Mahmoud A.

    2014-11-01

    An isothermal entropy change of 240 nm (111)-oriented PMN-PT 65/35 film near the ferroelectric Curie temperature, relative cooling power (RCP) and change of heat capacity have been investigated. The extracted data characterized giant isothermal entropy change of more than 16 J/kg K in electric field shift ΔE of 455 kV cm-1, which is nearly twice than that found for PbZr0.95Ti0.05O3 thin film at 492 kV cm-1 near the Curie point. Furthermore, the RCP ≈ 700 J/kg and change of heat capacity ≈ 233 J/kg K in electric field shift ΔE of 747 kV cm-1.

  12. Preparation of Potassium Ferrate from Spent Steel Pickling Liquid

    Directory of Open Access Journals (Sweden)

    Yu-Ling Wei

    2015-09-01

    Full Text Available Potassium ferrate (K2FeO4 is a multi-functional green reagent for water treatment with considerable combined effectiveness in oxidization, disinfection, coagulation, sterilization, adsorption, and deodorization, producing environment friendly Fe(III end-products during the reactions. This study uses a simple method to lower Fe(VI preparation cost by recycling iron from a spent steel pickling liquid as an iron source for preparing potassium ferrate with a wet oxidation method. The recycled iron is in powder form of ferrous (93% and ferric chlorides (7%, as determined by X-ray Absorption Near Edge Spectrum (XANES simulation. The synthesis method involves three steps, namely, oxidation of ferrous/ferric ions to form ferrate with NaOCl under alkaline conditions, substitution of sodium with potassium to form potassium ferrate, and continuously washing impurities with various organic solvents off the in-house ferrate. Characterization of the in-house product with various instruments, such as scanning electron microscopy (SEM, ultraviolet-visible (UV-Vis, X-ray diffraction (XRD, and X-ray absorption spectroscopy (XAS, proves that product quality and purity are comparative to a commercialized one. Methylene blue (MB de-colorization tests with in-house potassium ferrate shows that, within 30 min, almost all MB molecules are de-colorized at a Fe/carbon mole ratio of 2/1.

  13. Formation of (111) orientation-controlled ferroelectric orthorhombic HfO2 thin films from solid phase via annealing

    Science.gov (United States)

    Mimura, Takanori; Katayama, Kiliha; Shimizu, Takao; Uchida, Hiroshi; Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J.; Sakata, Osami; Funakubo, Hiroshi

    2016-08-01

    0.07YO1.5-0.93HfO2 (YHO7) films were prepared on various substrates by pulse laser deposition at room temperature and subsequent heat treatment to enable a solid phase reaction. (111)-oriented 10 wt. % Sn-doped In2O3(ITO)//(111) yttria-stabilized zirconia, (111)Pt/TiOx/SiO2/(001)Si substrates, and (111)ITO/(111)Pt/TiOx/SiO2/(001)Si substrates were employed for film growth. In this study, X-ray diffraction measurements including θ-2θ measurements, reciprocal space mappings, and pole figure measurements were used to study the films. The film on (111)ITO//(111)yttria-stabilized zirconia was an (111)-orientated epitaxial film with ferroelectric orthorhombic phase; the film on (111)ITO/(111)Pt/TiOx/SiO2/(001)Si was an (111)-oriented uniaxial textured film with ferroelectric orthorhombic phase; and no preferred orientation was observed for the film on the (111)Pt/TiOx/SiO2/(001)Si substrate, which does not contain ITO. Polarization-hysteresis measurements confirmed that the films on ITO covered substrates had saturated ferroelectric hysteresis loops. A remanent polarization (Pr) of 9.6 and 10.8 μC/cm2 and coercive fields (Ec) of 1.9 and 2.0 MV/cm were obtained for the (111)-oriented epitaxial and uniaxial textured YHO7 films, respectively. These results demonstrate that the (111)-oriented ITO bottom electrodes play a key role in controlling the orientation and ferroelectricity of the phase formation of the solid films deposited at room temperature.

  14. Impacts of ferrate oxidation on natural organic matter and disinfection byproduct precursors.

    Science.gov (United States)

    Jiang, Yanjun; Goodwill, Joseph E; Tobiason, John E; Reckhow, David A

    2016-06-01

    This study investigated the effectiveness of ferrate (Fe(VI)) oxidation in combination with ferric chloride coagulation on the removal of natural organic matter (NOM) and disinfection byproduct (DBP) precursors. Twelve natural waters were collected and four treatment scenarios were tested at bench-scale. Results showed that intermediate-ferrate treatment (i.e., coagulation and particle removal followed by ferrate oxidation) was most effective followed by pre-ferrate treatment (i.e., ferrate oxidation followed by coagulation and particle removal (conventional treatment)) or conventional treatment alone (i.e., no oxidation), and the least effective was ferrate oxidation alone (i.e., no coagulation). At typical doses, direct ferrate oxidation of raw water decreased DBP formation potentials (DBPFPs) by about 30% for trihalomethanes (THMs), 40% for trihaloacetic acids (THAAs), 10% for dihaloacetic acids (DHAAs), 30% for dihaloacetonitriles (DHANs), and 5% for haloketones (HKs). The formation potential of chloropicrin (CP) consistently increased after direct ferrate oxidation. Pre-ferrate followed by conventional treatment was similar to conventional treatment alone for NOM and DBP precursor removal. Ferrate pre-oxidation had positive effects on subsequent coagulation/particle removal for THM and THAA precursor removal and may allow the use of lower coagulant doses due to the Fe(III) introduced by ferrate decomposition. On the other hand, intermediate-ferrate resulted in substantially improved removal of NOM and DBP precursors, which can be attributed to initial removal by coagulation and particle removal, leaving precursors that are particularly susceptible to oxidation by ferrate. The Fe(III) resulting from ferrate decay during intermediate-ferrate process was primarily present as particulate iron and could be effectively removed by filtration.

  15. Highly (110)- and (111)-oriented BiFeO3 films on BaPbO3 electrode with Ru or Pt /Ru barrier layers

    Science.gov (United States)

    Lee, Chia-Ching; Wu, Jenn-Ming; Hsiung, Chang-Po

    2007-04-01

    Highly (110)- and (111)-oriented BiFeO3 (BFO) films were fabricated with BaPbO3 (BPO )/Ru and BPO /Pt/Ru as electrode/barrier on Si substrates by rf-magnetron sputtering. The BPO /Ru and BPO /Pt/Ru stacks both induce oriented BFO films and act as diffusion barriers. The (110)- and (111)-oriented BFO films possess excellent ferroelectric properties with only minor leakage. The values of remnant polarization are almost the same, about 42μC/cm2, for (110)- and (111)-oriented BFO films. However, polarization measured under varying pulse widths demonstrates that the switching polarization in (111)-oriented BFO films is higher than in (110)-oriented films. Additionally, (111)-oriented BFO films exhibit better retention properties than (110)-oriented films.

  16. Deposition of highly (111)-oriented PZT thin films by using metal organic chemical deposition

    CERN Document Server

    Bu, K H; Choi, D K; Seong, W K; Kim, J D

    1999-01-01

    Lead zirconate titanate (PZT) thin films have been grown on Pt/Ta/SiNx/Si substrates by using metal organic chemical vapor deposition with Pb(C sub 2 H sub 5) sub 4 , Zr(O-t-C sub 4 H sub 9) sub 4 , and Ti(O-i-C sub 3 H sub 7) sub 4 as source materials and O sub 2 as an oxidizing gas. The Zr fraction in the thin films was controlled by varying the flow rate of the Zr source material. The crystal structure and the electrical properties were investigated as functions of the composition. X-ray diffraction analysis showed that at a certain range of Zr fraction, highly (111)-oriented PZT thin films with no pyrochlore phases were deposited. On the other hand, at low Zr fractions, there were peaks from Pb-oxide phases. At high Zr fractions, peaks from pyrochlore phase were seen. The films also showed good electrical properties, such as a high dielectric constant of more than 1200 and a low coercive voltage of 1.35 V.

  17. Induced Superconductivity and Engineered Josephson Tunneling Devices in Epitaxial (111)-Oriented Gold/Vanadium Heterostructures.

    Science.gov (United States)

    Wei, Peng; Katmis, Ferhat; Chang, Cui-Zu; Moodera, Jagadeesh S

    2016-04-13

    We report a unique experimental approach to create topological superconductors by inducing superconductivity into epitaxial metallic thin film with strong spin-orbit coupling. Utilizing molecular beam epitaxy technique under ultrahigh vacuum conditions, we are able to achieve (111) oriented single phase of gold (Au) thin film grown on a well-oriented vanadium (V) s-wave superconductor film with clean interface. We obtained atomically smooth Au thin films with thicknesses even down to below a nanometer showing near-ideal surface quality. The as-grown V/Au bilayer heterostructure exhibits superconducting transition at around 3.9 K. Clear Josephson tunneling and Andreev reflection are observed in S-I-S tunnel junctions fabricated from the epitaxial bilayers. The barrier thickness dependent tunneling and the associated subharmonic gap structures (SGS) confirmed the induced superconductivity in Au (111), paving the way for engineering thin film heterostructures based on p-wave superconductivity and nano devices exploiting Majorana Fermions for quantum computing.

  18. Preparation and Aromatic Hydrocarbon Removal Performance of Potassium Ferrate

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2014-01-01

    Full Text Available This experiment adopts the hypochlorite oxidation method to constantly synthesize potassium ferrate. Under the condition of micropolluted source water pH and on the basis of naphthalene, phenanthrene, and pyrene as research objects, the effects of different systems to remove aromatic hydrocarbons were studied. Various oxidation systems to remove phenanthrene intermediate are analyzed and the detailed mechanisms for removal of phenanthrene are discussed. The study found that the main intermediate of potassium ferrate system to transform phenanthrene is 9,10-phenanthraquinone and its area percentage reached 82.66%; that is, 9,10-phenanthraquinone is the key entity to remove phenanthrene.

  19. Investigation of electrochemical synthesis of ferrate - Part II: Optimization of the process parameters of ferrate(VI electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan I.

    2010-01-01

    Full Text Available In part I [1] of the investigation the behavior of iron and selected low carbon steels in concentrated (10M - 15 M water solution of NaOH and KOH in wide range of electrode potentials, between hydrogen evolution reaction and oxygen evolution reaction, is investigated and discussed. On the base of experimental data obtained by LSV and galvanostatic pulse methods, it is concluded [1] that efficient synthesis of ferrate (VI can be expected in the region of anodic potentials between + 0,55 V and + 0,75 V against Hg|HgO reference electrode. In this paper optimization of electrolysis parameters of the electrochemical synthesis of ferrate(VI is elaborated. The most important parameters chosen for optimization process were: anode material, alkaline electrolyte concentration, regime of electrical potential control, current density and electrolyte temperature. The best current efficiency and yield of ferrate(VI synthesis of the explored anode materials (electrical steel, low carbon cold rolled steel plate, and structural steel is obtained when electrical steel with 3 wt% of silicon is applied. The worst current efficiency is obtained with anodes made of structural steel with higher concentration of manganese, chromium and nickel. The influence of alloying elements on the process of electrochemical synthesis of ferrate(VI is discussed in terms of their influence on formation and stability of anodic passive layer and oxygen evolution reaction. The increase of electrolyte concentration from 10M to 15M NaOH and KOH provided the increase of current efficiency with maximum obtained for 14M NaOH. The yield of ferrate(VI synthesis increases with temperature raise, having maximal value at about +50°C, and after that, at higher temperatures, instability of ferrate(VI increases and the yield of synthesis lessens. Considering the influence of electrical regime control it is concluded that the biggest yield of ferrate(VI can be expected with constant anodic potential

  20. Effect of post-treatment on photocatalytic oxidation activity of (111 oriented NaNbO3 film

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    2015-10-01

    Full Text Available We investigate the impact of post-treatment on photocatalytic oxidation activity of (111 oriented NaNbO3 film prepared by pulse laser deposition. Some impurities such as Na2Nb4O11 and bigger particles appear in the treated samples. The activity of rhodamine B degradation with N2 purge increases with the amount of ⋅OH, the sample treated under H2/Ar(7% being the highest activity, followed by under air and untreated one; the opposite trend is observed when the system was without N2 purge.

  1. Phase diagrams and physical properties of (111) oriented Pb(Zr1-xTix)O3 thin films

    Science.gov (United States)

    Qiu, J. H.; Chen, Z. H.; Wang, X. Q.; Yuan, N. Y.; Ding, J. N.

    2016-11-01

    Based on the phenomenological Landau-Devonshire theory, the phase diagrams and physical properties of (111) oriented Pb(Zr1-xTix)O3 thin films are investigated. The "misfit strain-temperature" phase diagrams of (111) oriented thin films are more complex than that of (001) oriented thin films due to the appearance of nonlinear coupling terms in the thermodynamic potential. The monoclinic MA phase, the triclinic γ phase, the orthorhombic O phase, and the cubic C phase are stable. The compressive misfit strain induces the monoclinic MA phase, meanwhile the tensile misfit strain is beneficial to make the triclinic γ phase and the orthorhombic O phase stable. The ferroelectric and dielectric properties are calculated which are in great agreement with the experimental measurements. Moreover, the Pb(Zr0.5Ti0.5)O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the large longitudinal dielectric and piezoelectric properties which are in accordance with the other theoretical results. Most importantly, the tensile misfit strain is prone to induce the larger dielectric and piezoelectric properties than that of compressive misfit strain, which may provide the guidance for experimental research.

  2. Mente y cerebro en el pensamiento de Ferrater Mora

    OpenAIRE

    2008-01-01

    En un momento en el que los nombres propios de filosofías distintas estuvieron casi obligadamente de moda, Ferrater sugirió el nombre de integracionismo como el más adecuado a su forma de pensar, a su trayectoria filosófica. Los análisis de Ferrater respecto al problema de la relación entre la mente y el cerebro son un testimonio más de esa actitud abierta y conciliadora, de su capacidad para aunar el análisis lógico con la intuición filosófica, con la afirmación de que la realidad es muy amp...

  3. Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?

    Science.gov (United States)

    Sofer, Zdeněk; Luxa, Jan; Jankovský, Ondřej; Sedmidubský, David; Bystroň, Tomáš; Pumera, Martin

    2016-09-19

    It is well established that graphene oxide can be prepared by the oxidation of graphite using permanganate or chlorate in an acidic environment. Recently, however, the synthesis of graphene oxide using potassium ferrate(VI) ions has been reported. Herein, we critically replicate and evaluate this new ferrate(VI) oxidation method. In addition, we test the use of potassium ferrate(VI) for the synthesis of graphene oxide under various experimental routes. The synthesized materials are analyzed by a number of analytical methods in order to confirm or disprove the possibility of synthesizing graphene oxide by the ferrate(VI) oxidation route. Our results confirm the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment and low oxidation power in neutral and alkaline environments.

  4. Applications of Ferrate(VI) to Wastewater Reclamation and Water Treatment

    Science.gov (United States)

    Kim, H.; Choi, H.; Lee, K.; Nam, J.; Kim, I.

    2010-12-01

    The estimated amount of water resources is about 63 billion cubic meters in Korea. However, due to the lack of precipitation during the dry season, natural flows are not enough for the water supply. In addition, since the lack of water affects water quality, environmental problems are occurred in natural and social systems. In this study, we investigated the application feasibility of ferrate(VI) systems to water and wastewater treatment. And we'd like to suggest an alternative solution for conservation and efficient reuse of the limited water resources. In the research area of environmental applications, a primary interest has been focused to the power of ferrate(VI) systems in the decomposition of pollutants in wastewater and industrial effluents due to its potential use as a strong, relatively non-toxic, and oxidizing agent for diverse environmental contaminants. Also ferrate(VI) has additional advantages as a very efficient coagulant and a sorbent of pollutants. We have analysed and compared several ferrate(VI) manufacturing processes, especially focused on the electro chemical methods(Fig. 1). And we have investigated the applications of the manufactured ferrate(VI) in our own laboratory and the commercial ferrate(VI) to decomposition of persistent organic pollutants in water. Under optimal conditions, the removal efficiencies of 2-chlorophenol and benzothiophene were above 90%(Fig. 2). The ferrate system(VI) is promising and can be one of the most efficient alternatives among the advanced oxidation processes(AOPs) for degradation of persistent organic pollutants, and is an innovative technology for the wastewater reclamation, water reusing systems, and water treatment systems. Fig 1. Comparison of Electro-Chemical Ferrate(VI) manufacturing Processes Fig 2. Degradation of 2-Chlorophenol and Bezothiophene by Ferrate. (Experimental Conditions : 2-CP = 3ppm, BT = 5ppm, NaClO4 = 0.05M)

  5. Settleability and characteristics of ferrate(VI)-induced particles in advanced wastewater treatment.

    Science.gov (United States)

    Zheng, Lei; Deng, Yang

    2016-04-15

    Ferrate(VI) as an emerging water treatment agent has recently recaptured interests for advanced wastewater treatment. A large number of studies were published to report ferrate(VI)-driven oxidation for various water contaminants. In contrast, very few efforts were made to characterize ferrate(VI) resultant particles in water and wastewater. In this study, jar tests were performed to examine the settleability and characteristics of ferrate(VI)-induced iron oxide particles, particularly the non-settable fraction of these particles, after ferrate(VI) reduction in a biologically treated municipal wastewater. The particle settleability was evaluated through the measurement of turbidity and particulate iron concentration in the supernatant with the settling time. Results showed that a majority of ferrate(VI)-induced iron oxide aggregates remained suspended and caused an increased turbidity. For example, at a Fe(VI) dose of 5.0 mg/L and pH 7.50, 82% of the added iron remained in the supernatant and the turbidity was 8.97 NTU against the untreated sample turbidity (2.33 NTU) after 72-h settling. The poor settling property of these particles suggested that coagulation and flocculation did not perform well in the ferrate(VI) treatment. Particle size analysis and transmission electron microscopy (TEM) revealed that nano-scale particles were produced after ferrate(VI) decomposition, and gradually aggregated to form micro-scale larger particles in the secondary effluent. Zeta potentials of the non-settable ferrate(VI) resultant aggregates varied between -7.36 and -8.01 mV at pH 7.50 during the 72-h settling. The negative surface charges made the aggregates to be relatively stable in the wastewater matrix.

  6. Reaction kinetics and oxidation products formation in the degradation of ciprofloxacin and ibuprofen by ferrate(VI).

    Science.gov (United States)

    Zhou, Zhengwei; Jiang, Jia-Qian

    2015-01-01

    The treatment of ciprofloxacin (CIP) and ibuprofen (IBU) in test solutions by ferrate(VI) was investigated in this study. A series of jar test was performed in bench-scale at pH 6-9 and ferrate(VI) dose of 1-5 mg L(-1). Results demonstrated that ferrate(VI) removed CIP from test solutions efficiently, with above 70% of reduction under study conditions. In contrary, the removal rates of IBU were very low, less than 25% in all conditions. Raising ferrate(VI) dose improved the treatment performance, while the influence of solution pH was not significant at pH 6-9 compared with that of ferrate(VI) dose. In addition, kinetic studies of ferrate(VI) with both compounds were carried out at pH 8 and pH 9 (20 °C). Ferrate(VI) had a much higher reactivity with CIP than IBU at pH 8 and pH 9, with CIP's apparent second-order rate constants of 113.7±6.3 M(-1) s(-1) and 64.1±1.0 M(-1) s(-1), respectively. The rate constants of ferrate(VI) with IBU were less than 0.2 M(-1) s(-1) at pH 8 and pH 9. Furthermore, seven oxidation products (OPs) were formed during CIP degradation by ferrate(VI). The attack on the piperazinyl ring of the CIP by ferrate(VI) appeared to lead to the cleavage or hydroxylation of the rings, and the attack on the quinolone moiety by ferrate(VI) might lead to the cleavage of the double bond at the six-member heterocyclic ring. No OPs of IBU were detected during ferrate(VI) oxidation due to very small part of IBU was degraded by ferrate(VI). Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Highly effective strain-induced band-engineering of (111) oriented, direct-gap GeSn crystallized on amorphous SiO2 layers

    Science.gov (United States)

    Li, Haofeng; Wang, Xiaoxin; Liu, Jifeng

    2016-03-01

    We demonstrate highly effective strain-induced band-engineering of (111) oriented direct-gap Ge1-xSnx thin films (0.074 GeSn films also demonstrate high thermal stability, offering both excellent direct-gap optoelectronic properties and fabrication/operation robustness for integrated photonics.

  8. Efficient iodination of aromatic compounds using potassium ferrate supported on montmorillonite

    Institute of Scientific and Technical Information of China (English)

    Hoda Keipour; Mohammad A. Khalilzadeh; Bita Mohtat; Abolfazl Hosseini; Daryoush Zareyee

    2011-01-01

    Potassium ferrate impregnated on montmorillonite is a mild, cheap, and non-toxic reagent for the iodination of phenols, including naphthol, aromatic amines, and heterocyclic substrates in fair to excellent yields by a simple isolation procedure.

  9. Growth of (111)-oriented epitaxial and textured ferroelectric Y-doped HfO2 films for downscaled devices

    Science.gov (United States)

    Katayama, Kiliha; Shimizu, Takao; Sakata, Osami; Shiraishi, Takahisa; Nakamura, Syogo; Kiguchi, Takanori; Akama, Akihiro; Konno, Toyohiko J.; Uchida, Hiroshi; Funakubo, Hiroshi

    2016-09-01

    In this study, the growth of (111)-oriented epitaxial and textured YO1.5-HfO2 (0.07:0.93 ratio) films using the pulsed laser deposition method is presented. Epitaxial films were prepared on ITO//(111)yttria-stabilized zirconia (YSZ) substrates (ITO: Sn-doped In2O3; YSZ: yttria-stabilized zirconia), while textured films were prepared on (111)Pt/TiOx/SiO2//Si substrates with and without an ITO buffer layer via the grain on grain coherent growth. Inserting an ITO layer increased the volume fraction of the ferroelectric orthorhombic phase. Both the epitaxial and uniaxially textured films exhibited similar ferroelectricity with a remanent polarization of around 10 μC/cm2 and a coercive field of 1.9 to 2.0 MV/cm. These results present us with a way of obtaining stable and uniform ferroelectric properties for each grain and device cells consisting of a small number of grains. This opens the door for ultimately miniaturized ferroelectric devices, such as ferroelectric field effect transistors with small gate length and resistive random access memory using ferroelectric tunnel junctions.

  10. The Evidence of Giant Surface Flexoelectric Field in (111) Oriented BiFeO3 Thin Film.

    Science.gov (United States)

    Yang, Tieying; Zhang, Xingmin; Chen, Bin; Guo, Haizhong; Jin, Kuijuan; Wu, Xiaoshan; Gao, Xingyu; Li, Zhong; Wang, Can; Li, Xiaolong

    2017-02-15

    In this work, the surface structure of a single-domain epitaxial BiFeO3 film with (111) orientation was investigated by in situ grazing incidence X-ray diffraction and X-ray reflectivity. We found that a large strain gradient exists in the surface region (2-3 nm) of the BiFeO3 film. The strain gradient is approximately 10(7) m(-1), which is 2 or 3 orders of magnitude larger than the value inside the film. Moreover, we found that a surface layer with a lower electron density compared with the underlying BiFeO3 layer exists on the surface of BiFeO3 film, and this layer exhibits an irreversible surface structure transition occurs at 500 K, which should be associated with the surface flexoelectric field. We considered that this large strain gradient is originated from the surface depolarization field of ferroelectrics. Our results suggest a coupling between the surface structure and the flexoelectricity and imply that the surface layer and properties would be controlled by the strain gradient in ferroelectric films.

  11. Treatment of combined sewer overflows using ferrate (VI).

    Science.gov (United States)

    Gandhi, Rohan; Ray, Ajay K; Sharma, Virender K; Nakhla, George

    2014-11-01

    This paper presents the results of a study conducted on the treatment of combined sewer overflows using ferrate (VI) [Fe (VI)]. At a Fe (VI) dose of 0.24 mg/L, total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), total biochemical oxygen demand (TBOD5), soluble biochemical oxygen demand (SBOD5), total suspended solids (TSS), volatile suspended solids (VSS), total phosphorus (TP), total nitrogen (TN), and soluble TN removal efficiencies of 71, 75, 69, 68, 72, 83, 64, 38, and 36%, respectively, were achieved. Kinetic studies revealed that a contact time of only 15 minutes is sufficient to achieve secondary effluent criteria. An innovative technique of using primary sludge (PS) and thickened waste activated sludge as a source for the in situ synthesis of ferrate was developed. A comparative study of treatment efficiencies achieved by Fe (VI) generated from different sources was done. At 0.1 mg/L dose of Fe (VI) synthesized from PS, TCOD, SCOD, TSS, VSS, TP, and TN removal efficiencies of 60, 62, 63, 67, 30, and 25%, respectively, were achieved.

  12. Magnetism and electronic structure of (001)- and (111)-oriented LaTiO{sub 3} bilayers sandwiched in LaScO{sub 3} barriers

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Yakui; Dong, Shuai, E-mail: sdong@seu.edu.cn [Department of Physics and Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189 (China)

    2015-05-07

    In this study, the magnetism and electronic structure of LaTiO{sub 3} bilayers along both the (001) and (111) orientations are calculated using the density functional theory. The band insulator LaScO{sub 3} is chosen as the barrier layer and substrate to obtain the isolating LaTiO{sub 3} bilayer. For both the (001)- and (111)-oriented cases, LaTiO{sub 3} demonstrates the G-type antiferromagnetism as the ground state, similar to the bulk material. However, the electronic structure is significantly changed. The occupied bands of Ti are much narrower in the (111) case, giving a nearly flat band. As a result, the exchange coupling between nearest-neighbor Ti ions is reformed in these superlattices, which will affect the Néel temperature significantly.

  13. Laser beam scanning microscope and piezoresponse force microscope studies on domain structured in 001-, 110-, and 111-oriented NaNbO3 films

    Science.gov (United States)

    Yamazoe, Seiji; Kohori, Akihiro; Sakurai, Hiroyuki; Kitanaka, Yuuki; Noguchi, Yuji; Miyayama, Masaru; Wada, Takahiro

    2012-09-01

    NaNbO3 (NN) films were epitaxially grown on SrRuO3/(001), (110), and (111)SrTiO3 substrates, and these NN films were characterized by a laser beam scanning microscope and a piezoresponse force microscope. The 001-oriented NN film had antiferroelectric 90° domains with 100 and 010 polarization axes and 90° domain walls exhibiting piezoresponse. The piezoresponding domain walls would be induced by ferroelasticity. On the other hand, the 110- and 111-oriented NN films possessed 60° domains. The 60° domains of 110-oriented NN film were constructed by antiferroelectric 11¯0 domain and piezoresponding {101} and {011} domains. In the case of 111-oriented NN, three kinds of 60° domains (11¯0 and 01¯1, 01¯1 and 101¯, and 101¯ and 11¯0) were observed. The fine domains with piezoresponse were also observed in the mixed region with the three 60° domains. From the stress measurement, we found that the difference in the domain structure of 001-, 110-, and 111-oriented NN films depends not only on the orientation direction but also on the stress from the substrate. Moreover, the stress and the induction of the piezoelectric domain also influence the dielectric behavior.

  14. Magnetic field-dependent polarization of (111)-oriented PZT–Co ferrite nanobilayer: Effect of Co ferrite composition

    Energy Technology Data Exchange (ETDEWEB)

    Khodaei, M. [Advanced Magnetic Materials Research Center, School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Seyyed Ebrahimi, S.A., E-mail: saseyyed@ut.ac.ir [Advanced Magnetic Materials Research Center, School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Jun Park, Yong [Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Son, Junwoo; Baik, Sunggi [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

    2015-05-15

    The perfect (111)-oriented PZT/CFO (CFO=CoFe{sub 2}O{sub 4}, Co{sub 0.8}Fe{sub 2.2}O{sub 4} and Co{sub 0.6}Mn{sub 0.2}Fe{sub 2.2}O{sub 4}) bilayer multiferroic thin films were grown on Pt(111)/Si substrate at 600 °C using pulsed laser deposition technique. The precision X-ray diffraction analysis (avoiding the shift of peak due to the sample misalignment) revealed that the CFO films on Pt(111)/Si substrate were under an out-of-plane contraction and deposition of PZT top layer led to more increase in the out-of-plane contraction, i.e. increase in the residual stresses. The PZT and CFO layers have significant effects on magnetic and ferroelectric properties of PZT/CFO bilayer films, respectively, leading to an enhanced in-plane magnetic anisotropy as well as increased and asymmetric polarization. The effect of composition of CFO layer on magnetic field-dependent polarization of PZT/CFO bilayer films was investigated by applying the magnetic field during P-E measurement. The polarization of PZT films were increased by applying the magnetic field as a result of strain transferred from magnetostrictive CFO underlayer. This increase in polarization for PZT/Co{sub 0.6}Mn{sub 0.2}Fe{sub 2.2}O{sub 4} was higher than that for PZT/Co{sub 0.8}Fe{sub 2.2}O{sub 4} and both of them were significantly higher than that for PZT/CoFe{sub 2}O{sub 4} bilayer film, which was discussed based on their magnetostriction properties. - Highlights: • The effect of composition of CFO on P–E characteristics of PZT/CFO films was investigated. • The polarization of PZT films were increased by applying the magnetic field. • The increasing polarization was a result of strain from magnetostrictive CFO underlayer.

  15. Chlorine decay and trihalomethane formation following ferrate(VI) preoxidation and chlorination of drinking water.

    Science.gov (United States)

    Li, Cong; Luo, Feng; Dong, Feilong; Zhao, Jingguo; Zhang, Tuqiao; He, Guilin; Cizmas, Leslie; Sharma, Virender K

    2017-08-19

    This paper presents the effect of preoxidation with ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) prior to chlorination on chlorine decay and formation of disinfection by-products in filtered raw water from a full-scale drinking water treatment plant. The rate of chlorine decay became significantly faster as the concentration of ferrate(VI) increased. Chlorine degradation followed two first-order decay reactions with rate constants k1 and k2 for fast and slow decay, respectively. Kinetic modeling established the relationships between k1 and k2 and varying dosages of chlorine and ferrate(VI). When ferrate(VI) was used as a pre-oxidant, the levels of trihalomethanes (trichloromethane (TCM), dichlorobromomethane (DCBM), dibromochloromethane (DBCM), and tribromomethane (TBM)) in water samples decreased as the ferrate(VI) concentration increased. The concentrations of these trihalomethanes followed the order TCM > DCBM ≈ DBCM > TBM. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. STUDI PENURUNAN ZAT WARNA ACID ORANGE 7 DENGAN PROSES OKSIDASI MENGGUNAKAN FERRAT (FeO42-

    Directory of Open Access Journals (Sweden)

    Dian Windy Dwiasi

    2011-05-01

    Full Text Available Colour removal from textile wastewater has been a matter of considerable interest during the last two decades, not only because of the potential toxicity of certain dyes but often due to their visibility in receiving waters and to their low biodegradability. Due to the limited success of some physical and chemical techniques for the treatment of dye effluents it is necessary to develop destructive systems leading to complete mineralization or, at least, to less harmful or easy-to-treat compounds. Oxidation processes using ferrate (FeO42- have been found to be very effective in the degradation of dye pollutants and for the treatment of waste waters from the textile industry. Acid Orange 7 (AO7 commonly used as a textile dye and could be degraded by ferrate oxidation processes. In the oxidation degradation of dye by ferrate process, effect of some parameters such as time, pH, and molar ratio of dye was examined at experimental condition. AO7 removal by this process was calculated to be equal to 12 minute at experimental condition. Ferrate can oxidize acid orange 7 effectively at optimum pH of 9.8, with the molar ratio of ferrate : acid orange 7 at 4:1. The percentages of acid orange 7 degradation reached to 98.9%.

  17. [Research on the degradation of BaP with potassium ferrate characterized by fluorescence].

    Science.gov (United States)

    Chen, Yu-Zhe; He, Qiang; Yu, Dan-Ni; Li, Si; Tan, Xue-Mei

    2012-07-01

    The degradation of Benzo(a)pyrene (BaP) by potassium ferrate was researched by means of multiple fluorescence spectroscopic methods such as synchronous, time-scan, excitation emission matrix (EEM) and photometry, under the optimal condition. Within the degradation process, the characteristics of the BaP's concentration at different time-intervals, and the kinetics of the degradation of BaP by potassium ferrate were discussed. From the experimental data, both synchronous and EEM spectra's results showed that the concentration of BaP was reduced 90% by potassium ferrate within 20 s after degradation, and the reaction process was very slow after 60 s. The degradation kinetic equation, ln(F0/Ft) = 0.563 2t + 0.171 2, (R2 = 0.994 2), was obtained through a convenient and fast way combining the time-scan fluorescence data and photometry data, and the photometry included the synchronous photometry and emission photometry. According to the kinetic equation, the degradation of BaP by potassium ferrate was in accord with the order of the first order reaction. So this article could provide a very useful conference for the research on the pollutant degradation by potassium ferrate, especially for the degradation process and the degradation mechanisms.

  18. Tertiary treatment of Berlin WWTP effluents with ferrate (Fe(VI)).

    Science.gov (United States)

    Hübner, U; Jekel, M

    2013-01-01

    New and higher standards in the EU water framework directive necessitate advanced treatment of secondary effluents for reduction of trace organic compounds (TrOCs) and nutrients before the discharge into receiving surface waters. Due to its dual function as oxidant and coagulant, ferrate is considered as a promising alternative for tertiary treatment. The oxidation of selected TrOCs and simultaneous flocculation of phosphates by ferrate was tested in batch experiments with secondary effluent from Berlin Ruhleben. The concentrations of carbamazepine (CBZ) and diclofenac were reduced by >90% with ferrate dosages of 6 mg/L as Fe. CBZ was transformed to 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one, which is known as the major product from the reaction of CBZ with ozone. In contrast to ozonation, no further transformation of this product was observed. The concentration of ibuprofen was not reduced by ferrate treatment. For efficient removal of 60-100 μg/L phosphate-P to values <20 μg/L, ferrate dosages of 3-4 mg/L as Fe were sufficient.

  19. Effect of Misfit Strain on Pyroelectric Properties of (111) Oriented Pb(Zr1-x Ti x ) O3 Thin Films

    Science.gov (United States)

    Qiu, Jian-Hua; Chen, Zhi-Hui; Wang, Xiu-Qin; Yuan, Ning-Yi; Ding, Jian-Ning

    2016-10-01

    Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1-xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1-xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1-xTix) O3 thin films can be adjusted by choosing the suitable substrates. Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, the research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology, Major Projects of Natural Science Research in Jiangsu Province under Grant Nos. 15KJA43002, 16KJD430006, and also sponsored by Qing Lan Project of Education Department of Jiangsu Province

  20. Broadband dielectric characterization of sapphire/TiOx/Ba₀.₃Sr₀.₇TiO₃ (111)-oriented thin films for the realization of a tunable interdigitated capacitor.

    Science.gov (United States)

    Ghalem, Areski; Ponchel, Freddy; Remiens, Denis; Legier, Jean-Francois; Lasri, Tuami

    2013-05-01

    A complete microwave characterization up to 67 GHz using specific coplanar waveguides was performed to determine the dielectric properties (permittivity, losses, and tunability) of sapphire/TiOx/Ba0.3Sr0.7TiO3 (BST) (111)-oriented thin films. To that end, BaxSr1-xTiO3 thin films were deposited by RF magnetron sputtering on sapphire (0001) substrate. To control the preferred (111) orientation, a TiOx buffer layer was deposited on sapphire. According to the detailed knowledge of the material properties, it has been possible to conceive, fabricate, and test interdigitated capacitors, the basic element for future microwave tunable applications. Retention of capacitive behavior up to 67 GHz and a tunability of 32% at 67 GHz at an applied voltage of 30 V (150 kV/cm) were observed. The Q-factor remains greater than 30 over the entire frequency band. The possibility of a complete characterization of the material for the realization of high-performance interdigitated capacitors opens the door to microwave device fabrication.

  1. A New Approach toward Cyanotype Photography Using Tris-(Oxalato)ferrate(III): An Integrated Experiment

    Science.gov (United States)

    Fiorito, Pablo Alejandro; Polo, Andre´ Sarto

    2015-01-01

    This work presents an approach that integrates the preparation of a coordination compound, potassium tris- (oxalato)ferrate(III), with its photochemical behavior and provides a possible application, the printing of a photograph using the cyanotype technique. Through this experiment, students can be taught several concepts that occur in a…

  2. A New Approach toward Cyanotype Photography Using Tris-(Oxalato)ferrate(III): An Integrated Experiment

    Science.gov (United States)

    Fiorito, Pablo Alejandro; Polo, Andre´ Sarto

    2015-01-01

    This work presents an approach that integrates the preparation of a coordination compound, potassium tris- (oxalato)ferrate(III), with its photochemical behavior and provides a possible application, the printing of a photograph using the cyanotype technique. Through this experiment, students can be taught several concepts that occur in a…

  3. Simultaneous desulfurization and denitrification from flue gas by Ferrate(VI).

    Science.gov (United States)

    Zhao, Yi; Han, Yinghui; Ma, Tianzhong; Guo, Tianxiang

    2011-05-01

    An innovative semidry process has been developed to simultaneously remove NO and SO₂ from flue gas. According to the conditions of the flue gas circulating fluidized bed (CFB) system, ferrate(VI) absorbent was prepared and added to humidified water, and the effects of the various influencing factors, such as ferrate(VI) concentration, humidified water pH, inlet flue gas temperature, residence time, molar ratio of Ca/(S+N), and concentrations of SO₂ and NO on removal efficiencies of SO₂ and NO were studied experimentally. Removal efficiencies of 96.1% for SO₂ and 67.2% for NO were obtained, respectively, under the optimal experimental conditions, in which the concentration of ferrate(VI) was 0.03 M, the humidified water pH was 9.32, the inlet flue gas temperature was 130 °C, the residence time was 2.2 s, and the molar ratio of Ca/(S+N) was 1.2. In addition, the reaction mechanism of simultaneous desulfurization and denitrification using ferrate(VI) was proposed.

  4. Comparison of coagulation, ozone and ferrate treatment processes for color, COD and toxicity removal from complex textile wastewater.

    Science.gov (United States)

    Malik, Sameena N; Ghosh, Prakash C; Vaidya, Atul N; Waindeskar, Vishal; Das, Sera; Mudliar, Sandeep N

    2017-09-01

    In this study, the comparative performance of coagulation, ozone, coagulation + ozone + coagulation and potassium ferrate processes to remove chemical oxygen demand (COD), color, and toxicity from a highly polluted textile wastewater were evaluated. Experimental results showed that ferrate alone had no effect on COD, color and toxicity removal. Whereas, in combination with FeSO4, it has shown the highest removal efficiency of 96.5%, 83% and 75% for respective parameters at the optimal dose of 40 mgL(-1) + 3 ml FeSO4 (1 M) in comparison with other processes. A seed germination test using seeds of Spinach (Spinacia oleracea) also indicated that ferrate was more effective in removing toxicity from contaminated textile wastewater. Potassium ferrate also produces less sludge with maximum contaminant removal, thereby making the process more economically feasible. Fourier transform infrared spectroscopy (FTIR) analysis also shows the cleavage of the chromophore group and degradation of textile wastewater during chemical and oxidation treatment processes.

  5. Double catholyte electrochemical approach for preparing ferrate-aluminum: a compound dxidant-coagulant for water purification

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ferrate is an excellent water treatment agent for its multi-functions in oxidation, disinfection, coagulation and adsorption, but its coagulation ability depends on its dosage and is after its oxidation. This paper focuses on preparing a new kind of ferrate combined with alum to enhance its coagulation function for water purification. An effective electrolysis reactor was designed and employed in the test. Some key parameters in the process of electrolysis concerning the preparation efficiency, such as the current density, temperature and alkalinity were also investigated. The proper conditions for ferrate-alum preparation were determined. In the condition of 5V given voltage, 6h electrolyzing interval, below 2% alum concentration (in weight), a combined liquid ferrate-alum products was successfully prepared, which contained 0.0294 mol/L FeO42-, 0.0302 mol/L total soluble ferron with 2% Al2O3. There was no insoluble ferron produced by controlling an optimum electrochemical condition.

  6. 光照对高铁酸盐溶液稳定性的影响%Effect of Light on the Stability of Ferrate Solution

    Institute of Scientific and Technical Information of China (English)

    高玉梅; 贾汉东

    2004-01-01

    The effects of light wave on the stability of fen'ate solution have been examined. The results showed that UV-light accelerates the decomposition of ferrate with decomposition rate 1.6 times as much as that in dark whereas infrared light has only unclear effect on the stability of ferrate, with decomposition rate 1.1 times as much as in dark. The polythene container is found to the best for preservation of ferrate solution in dark.

  7. Structure and magnetic properties of spinel-perovskite nanocomposite thin films on SrTiO3 (111) substrates

    Science.gov (United States)

    Kim, Dong Hun; Yang, Junho; Kim, Min Seok; Kim, Tae Cheol

    2016-09-01

    Epitaxial CoFe2O4-BiFeO3 nanocomposite thin films were synthesized on perovskite structured SrTiO3 (001) and (111) substrates by combinatorial pulsed laser deposition and characterized using scanning electron microscopy, x-ray diffraction, and vibrating sample magnetometer. Triangular BiFeO3 nanopillars were formed in a CoFe2O4 matrix on (111) oriented SrTiO3 substrates, while CoFe2O4 nanopillars with rectangular or square top surfaces grew in a BiFeO3 matrix on (001) substrates. The magnetic hysteresis loops of nanocomposites on (111) oriented SrTiO3 substrates showed isotropic properties due to the strain relaxation while those of films on SrTiO3 (001) substrates exhibited a strong out-of-plane anisotropy originated from shape and strain effects.

  8. Thin (111) oriented CoFe{sub 2}O{sub 4} and Co{sub 3}O{sub 4} films prepared by decomposition of layered cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Buršík, Josef, E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Soroka, Miroslav, E-mail: soroka@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Uhrecký, Róbert, E-mail: uhrecky@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Kužel, Radomír, E-mail: kuzel@karlov.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Mika, Filip, E-mail: filip.mika@isibrno.cz [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 147, 612 64 Brno (Czech Republic); Huber, Štěpán, E-mail: stepan.huber@vscht.cz [University of Chemistry and Technology, Faculty of Chemical Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-07-15

    Graphical abstract: Pole figures of NaCoO{sub 2} (left) and of CoFe{sub 2}O{sub 4} (right) films formed through the transformation of O3-type NaCoO{sub 2} phase in consequence of sodium deintercalation occurring at 800 °C. Films were prepared by chemical solution deposition on MgO(111) substrate. - Highlights: • Epitaxial Na(CoFe)O{sub 2} thin films by means of chemical solution deposition were prepared. • Oriented spinel films through transformation of Na(CoFe)O{sub 2} were obtained. • Orientation relation to MgO, SrTiO{sub 3} and Zr(Y)O{sub 2} substrates were determined. • Structural aspects of Na(CoFe)O{sub 2} → CoFe{sub 2}O{sub 4} transformation pathway were elucidated. - Abstract: The formation and structural characterization of highly (111)-oriented Co{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} films prepared by a novel procedure from 00l-oriented NaCoO{sub 2} and Na(CoFe)O{sub 2} is reported. The Na(CoFe)O{sub 2} films were deposited on MgO, SrTiO{sub 3}, LaAlO{sub 3}, and Zr(Y)O{sub 2} single crystals with (100) and (111) orientations by chemical solution deposition method and crystallized at 700 °C. Subsequently they were transformed into (111)-oriented spinel phase during post-growth annealing at 800–1000 °C. Morphology and structure of the films was investigated by means of scanning electron microscopy and X-ray diffraction. While all spinel films exhibit pronounced out-of-plane orientation irrespective of substrate, the rate of in-plane orientation strongly depend on lattice misfit values. Different epitaxial phenomena ranging from true one-to-one epitaxy to the existence of many-to-one epitaxy involving two or more orientations were determined by full 3D texture analysis.

  9. Green primary explosives: 5-nitrotetrazolato-N2-ferrate hierarchies.

    Science.gov (United States)

    Huynh, My Hang V; Coburn, Michael D; Meyer, Thomas J; Wetzler, Modi

    2006-07-05

    The sensitive explosives used in initiating devices like primers and detonators are called primary explosives. Successful detonations of secondary explosives are accomplished by suitable sources of initiation energy that is transmitted directly from the primaries or through secondary explosive boosters. Reliable initiating mechanisms are available in numerous forms of primers and detonators depending upon the nature of the secondary explosives. The technology of initiation devices used for military and civilian purposes continues to expand owing to variations in initiating method, chemical composition, quantity, sensitivity, explosive performance, and other necessary built-in mechanisms. Although the most widely used primaries contain toxic lead azide and lead styphnate, mixtures of thermally unstable primaries, like diazodinitrophenol and tetracene, or poisonous agents, like antimony sulfide and barium nitrate, are also used. Novel environmentally friendly primary explosives are expanded here to include cat[Fe(II)(NT)(3)(H(2)O)(3)], cat(2)[Fe(II)(NT)(4)(H(2)O)(2)], cat(3)[Fe(II)(NT)(5)(H(2)O)], and cat(4)[Fe(II)(NT)(6)] with cat = cation and NT(-) = 5-nitrotetrazolato-N(2). With available alkaline, alkaline earth, and organic cations as partners, four series of 5-nitrotetrazolato-N(2)-ferrate hierarchies have been prepared that provide a plethora of green primaries with diverse initiating sensitivity and explosive performance. They hold great promise for replacing not only toxic lead primaries but also thermally unstable primaries and poisonous agents. Strategies are also described for the systematic preparation of coordination complex green primaries based on appropriate selection of ligands, metals, and synthetic procedures. These strategies allow for maximum versatility in initiating sensitivity and explosive performance while retaining properties required for green primaries.

  10. The exploration of potassium ferrate(VI) as a disinfectant/coagulant in water and wastewater treatment.

    Science.gov (United States)

    Jiang, Jia-Qian; Wang, S; Panagoulopoulos, A

    2006-04-01

    This paper aims to explore potassium ferrate(VI) (K2FeO4) as an alternative water treatment chemical for both drinking water and wastewater treatment. The performance of potassium ferrate(VI) was evaluated in comparison with that of sodium hypochlorite (NaOCl) and that of NaOCl plus ferric sulphate (FS) or alum (AS). The dosages of ferrate(VI), NaOCl and FS/AS and sample pH values were varied in order to investigate the effects of these factors on the treatment performance. The study demonstrates that in drinking water treatment, ferrate(VI) can remove 10-20% more UV(254)-abs and DOC than FS for the same dose compared for natural pH range (6 and 8). The THMFP was reduced to less than 100 microg l(-1) by ferrate(VI) at a low dose. In addition to this, ferrate(VI) can achieve the disinfection targets (>6 log10 inactivation of Escherichia coliform (E. coli)) at a very low dose (6 mg l(-1) as Fe) and over wide working pH in comparison with chlorination (10 mg l(-1) as Cl2) plus coagulation (FS, 4 mg l(-1) as Fe). In wastewater treatment, ferrate(VI) can reduce 30% more COD, and kill 3log10 more bacteria compared to AS and FS at a similar or even smaller dose. Also, potassium ferrate(VI) can produce less sludge volume and remove more pollutants, which could make sludge treatment easier.

  11. Perovskite fever

    Science.gov (United States)

    2014-09-01

    Staggering increases in the performance of organic-inorganic perovskite solar cells have renewed the interest in these materials. However, further developments and the support from academic and industrial partners will hinge on the reporting of accurate efficiency values.

  12. Lithium-ferrate-based cathodes for molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lanagan, M.T.; Bloom, I.; Kaun, T.D. [Argonne National Lab., IL (United States)] [and others

    1996-12-31

    Argonne National Laboratory is developing advanced cathodes for pressurized operation of the molten carbonate fuel cell (MCFC) at {approximately}650{degrees}C. To be economically viable for stationary power generation, molten carbonate fuel cells must have lifetimes of more than 25,000 h while exhibiting superior cell performance. In the present technology, lithiated NiO is used as the cathode. Over the lifetime of the cell, however, N{sup 2+} ions tend to transport to the anode, where they are reduced to metallic Ni. With increased CO{sub 2} partial pressure, the transport of Ni increases because of the increased solubility of NiO in the carbonate electrolyte. Although this process is slow in MCFCs operated at 1 atm and a low CO{sub 2} partial pressure (about 0.1 atm), transport of nickel to the anode may be excessive at a higher pressure (e.g., 3 atm) and a high CO{sub 2} partial pressure (e.g., about 0.3 arm). This transport is expected to lead eventually to poor MCFC performance and/or short circuiting. Several alternative cathode compositions have been explored to reduce cathode solubility in the molten salt electrolyte. For example, LiCoO{sub 2} has been studied extensively as a potential cathode material. The LiCoO{sub 2} cathode has a low resistivity, about 10-cm, and can be used as a direct substitute for NiO. Argonne is developing advanced cathodes based on lithium ferrate (LiFeO{sub 2}), which is attractive because of its very low solubility in the molten (Li,K){sub 2}CO{sub 3} electrolyte. Because of its high resistivity (about 3000-cm), however, LiFeO{sub 2} cannot be used as a direct substitute for NiO. Cation substitution is, therefore, necessary to decrease resistivity. We determined the effect of cation substitution on the resistivity and deformation of LiFeO{sub 2}. The substituents were chosen because their respective oxides as well as LiFeO{sub 2} crystallize with the rock-salt structure.

  13. Sequential multi-drop coating method for large crystallized α-(NH2)2CHPbI3 and mixed-organic-cation perovskite films for highly efficient mesoscopic perovskite solar cells

    Science.gov (United States)

    Zhao, Yanhong; Xu, Xin; Zhang, Huiyin; Shi, Jiangjian; Zhu, Lifeng; Wu, Huijue; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2017-08-01

    A simplified multi-drop coating method that improves the grain size and film quality is introduced to construct and stabilize a pure α-phase formamidinium (FA) lead iodide ((NH2)2CHPbI3, FAPbI3) perovskite layer. The developed method is then extended to fabricate an FA and methylammonium (MA) (FA/MA) mixed cation perovskite film under ambient conditions. The acquired FAPbI3 film contains micron-sized large grains with preferred [111] orientation, which dramatically reduced the grain boundary area and the associated charge recombination to provide high short-circuit current densities and power conversion efficiencies (PCE) of up to 23.86 mA cm-2 and 17.66%, respectively. The open-circuit voltage of the device and the efficiency are further improved after extending this method to the FA/MA mixed perovskite film. Finally, the highest PCE reached 19.3%.

  14. Mössbauer study on the gamma radiolysis of anhydrous cesium tris (oxalato) ferrate(III)

    Science.gov (United States)

    Ladriere, J.; Senterre, V.; Apers, D.

    1992-04-01

    The final product of the gamma radiolysis of anhydrous cesium tris(oxalato) ferrate(III) has been identified by Mössbauer spectroscopy as Cs2Fe(ox)2. The radiolytic decomposition proceeds as a first-order process due to the original compound depletion and to the radiolytic stability of the ferrous compound. Lamb-Mössbauer factors measurements indicate that the recoilless fractions of the iron species are practically unaffected by the radiolysis.

  15. Two-dimensional electron gas at surfaces of (001), (110), and (111) oriented SrTiO3 induced by Ar+-irradiation

    Science.gov (United States)

    Miao, Ludi; Du, Renzhong; Yin, Yuewei; Li, Qi

    2015-03-01

    Two-dimensional electron gases (2DEGs) at transition metal oxide surfaces and interfaces have attracted much attention due to their fascinating exotic properties such as superconductivity, large magneto-resistance (MR), and ferromagnetism. We have created 2DEGs at the surfaces of (001), (110), and (111) oriented SrTiO3 (STO) by Ar+-irradiation and measured their transport properties. The 2DEGs exhibit a fully metallic behavior with the 2D charge carrier density around 2 ×1014 cm-2 and the mobility as large as 5500 cm2V-1s-1 at low temperatures, which is tunable by electric fields applied through STO back gates. We have measured MR anisotropy of the 2DEGs at surfaces of STO with all orientations. We observed combinations of two types of components in their anisotropic MR at low temperatures. While the first type is an STO-orientation-independent two-fold component results from the Lorentz force effect, the second type shows stark differences between these 2DEGs as a consequence of distinct Fermi surface symmetries with different STO orientations. Indeed, it is four-fold for STO (001), two-fold for STO (110) and six-fold for STO (111), respectively.

  16. Temperature effects on interface polarons in a strained (111)-oriented zinc-blende GaN/AlGaN heterojunction under pressure

    Institute of Scientific and Technical Information of China (English)

    Zhang Min; Ban Shiliang

    2009-01-01

    The properties of interface polarons in a strained (111)-oriented zinc-blende GaN/A1xGa1-xN heterojunc-tion at finite temperature under hydrostatic pressure are investigated by adopting a modified LLP variational method and a simplified coherent potential approximation. Considering the effect of hydrostatic pressure on the bulk longitu-dinal optical phonon mode, two branches interface-optical phonon modes and strain, respectively, we calculated the polaronic self-trapping energy and effective mass as functions of temperature, pressure and areal electron density. The numerical result shows that both of them near linearly increase with pressure but the self-trapping energies are nonlinear monotone increasing with increasing of the areal electron density. They are near constants below a range of temperature whereas decrease dramatically with increasing temperature beyond the range. The contributions from the bulk longitudinal optical phonon mode and one branch of interface optical phonon mode with higher frequency are important whereas the contribution from another branch of interface optical phonon mode with lower frequency is extremely small so that it can be neglected in the further discussion.

  17. Phenomenological theory of phase transitions in epitaxial BaxSr1-xTiO3 thin films on (111)-oriented cubic substrates

    Science.gov (United States)

    Shirokov, V. B.; Shakhovoy, R. A.; Razumnaya, A. G.; Yuzyuk, Yu. I.

    2015-07-01

    A phenomenological thermodynamic theory of BaxSr1-xTiO3 (BST-x) thin films epitaxially grown on (111)-oriented cubic substrates is developed using the Landau-Devonshire approach. The group-theoretical analysis of the low-symmetry phases was performed taking into account two order parameters: the polarization related to ionic shifts in polar zone-center F1u mode and the out-of-phase rotation of TiO6 octahedra corresponding to the R25 zone-boundary mode in the parent cubic phase P m 3 ¯ m . The eight-order thermodynamic potential for BST-x solid solutions was developed and analyzed. We constructed the "concentration-misfit strain" phase diagram for BST-x thin films at room temperature and found that polar rhombohedral R3m phase with the polarization normal to the substrate is stable for x > 0.72 and negative misfit strains, while ferroelectric monoclinic C2 and Cm phases with in-plane polarization are stable for much smaller x and positive or slightly negative misfit strains. We constructed the "temperature-misfit strain" phase diagrams for several concentrations (x = 1, 0.8, 0.6, 0.4, and 0.2). Systematic changes of the phase transition lines between the paraelectric and ferroelectric phases are discussed. The phase diagrams are useful for practical applications in thin-film engineering.

  18. Francisco Romero y las cartas de los exiliados españoles: José Ferrater Mora

    OpenAIRE

    2016-01-01

    El propósito de este artículo es analizar las cartas entre Francisco Romero y José Ferrater Mora durante sus vidas. Se consideran algunos de los aspectos que compartieron acerca de sus trabajos e ideas en el contexto intelectual y político. El artículo se desarrolla en cuatro partes: 1. La Guerra Civil y los intelectuales españoles exiliados. 2. La colección epistolar de Francisco Romero. 3. José Ferrater Mora y sus cartas. 4. Breves conclusiones. REVISTA GRUPO 1. The aim of this article ...

  19. Application of the Perovskite Ceramics to Conditioning of the Long-Lived Fraction of HLW

    Energy Technology Data Exchange (ETDEWEB)

    Cherniavskaya, N. E.; Chizhevskaya, S. V.; Ochkin, A. V.

    2002-02-25

    High level waste (HLW) partitioning concept includes separation of a long-lived fraction following by its immobilization in ceramics. Improved process flow sheet suggested for implementation at PA ''Mayak'' implies production of a long-lived HLW fraction with rare earth elements (REE) as major components, Am and Cm as minor constituents, and only traces of U, Pu, and corrosion products (iron group elements). Because most of the elements occurred are trivalent, one of the most promising host phase is supposed to be REE aluminate or ferrate with perovskite structure. Major advantages of the perovskite are incorporation of trivalent REEs and actinides, simultaneous incorporation of residual corrosion products, flexibility of perovskite structure allowing accommodation of traces of tetravalent actinides (U, Pu), high chemical durability, and high HLW volume reduction. High melting points of the perovskites makes problematic melting route, therefore, cold pressing and sintering method is more preferable. In order to reduce sintering temperature pre-treatment of ceramic batches with high mechanical energy has been studied.

  20. Application of the Perovskite Ceramics to Conditioning of the Long-Lived Fraction of HLW

    Energy Technology Data Exchange (ETDEWEB)

    Cherniavskaya, N. E.; Chizhevskaya, S. V.; Ochkin, A. V.

    2002-02-25

    High level waste (HLW) partitioning concept includes separation of a long-lived fraction following by its immobilization in ceramics. Improved process flow sheet suggested for implementation at PA ''Mayak'' implies production of a long-lived HLW fraction with rare earth elements (REE) as major components, Am and Cm as minor constituents, and only traces of U, Pu, and corrosion products (iron group elements). Because most of the elements occurred are trivalent, one of the most promising host phase is supposed to be REE aluminate or ferrate with perovskite structure. Major advantages of the perovskite are incorporation of trivalent REEs and actinides, simultaneous incorporation of residual corrosion products, flexibility of perovskite structure allowing accommodation of traces of tetravalent actinides (U, Pu), high chemical durability, and high HLW volume reduction. High melting points of the perovskites makes problematic melting route, therefore, cold pressing and sintering method is more preferable. In order to reduce sintering temperature pre-treatment of ceramic batches with high mechanical energy has been studied.

  1. Oxidation of triclosan by ferrate: Reaction kinetics, products identification and toxicity evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Yang Bin [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Ying Guangguo, E-mail: guang-guo.ying@csiro.au [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Zhao Jianliang; Zhang Lijuan; Fang Yixiang [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Nghiem, Long Duc [School of Civil Mining and Environmental Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2011-02-15

    Research highlights: {yields} Triclosan reacted rapidly with ferrate. {yields} Oxidation resulted in a decrease in algal toxicity. {yields} No inhibition of algae growth from ferrate. - Abstract: The oxidation of triclosan by commercial grade aqueous ferrate (Fe(VI)) was investigated and the reaction kinetics as a function of pH (7.0-10.0) were experimentally determined. Intermediate products of the oxidation process were characterized using both GC-MS and RRLC-MS/MS techniques. Changes in toxicity during the oxidation process of triclosan using Fe(VI) were investigated using Pseudokirchneriella subcapitata growth inhibition tests. The results show that triclosan reacted rapidly with Fe(VI), with the apparent second-order rate constant, k{sub app}, being 754.7 M{sup -1} s{sup -1} at pH 7. At a stoichiometric ratio of 10:1 (Fe(VI):triclosan), complete removal of triclosan was achieved. Species-specific rate constants, k, were determined for reaction of Fe(VI) with both the protonated and deprotonated triclosan species. The value of k determined for neutral triclosan was 6.7({+-}1.9) x 10{sup 2} M{sup -1} s{sup -1}, while that measured for anionic triclosan was 7.6({+-}0.6) x 10{sup 3} M{sup -1} s{sup -1}. The proposed mechanism for the oxidation of triclosan by the Fe(VI) involves the scission of ether bond and phenoxy radical addition reaction. Coupling reaction may also occur during Fe(VI) degradation of triclosan. Overall, the degradation processes of triclosan resulted in a significant decrease in algal toxicity. The toxicity tests showed that Fe(VI) itself dosed in the reaction did not inhibit green algae growth.

  2. Mössbauer effect studies on alkali tris (malonato) ferrates(III)

    Science.gov (United States)

    Bassi, P. S.; Randhawa, B. S.; Kaur, Sandeep

    1986-02-01

    Mössbauer spectra of alkali tris(malonato) ferrates(III) i.e. M3[Fe(C3H2O4)3].4H2O(M=Li, Na, K, NH4) at 298±2K display a single broad absorption band due to spin lattice relaxation effect. The isomer shift values indicate these complexes to be high spin with octahedral symmetry. The isomer shift shows a decreasing trend with the increase in electronegativity/polarizing power of the substituent cation (Li+, Na+, K+, NH4 +). A linear correlation between isomer shift values and the (Fe-O) stretching freguencies has also been observed.

  3. Formation of assimilable organic carbon during oxidation of natural waters with ozone, chlorine dioxide, chlorine, permanganate, and ferrate.

    Science.gov (United States)

    Ramseier, Maaike K; Peter, Andreas; Traber, Jacqueline; von Gunten, Urs

    2011-02-01

    Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Addressing harmful algal blooms (HABs) impacts with ferrate(VI): Simultaneous removal of algal cells and toxins for drinking water treatment.

    Science.gov (United States)

    Deng, Yang; Wu, Meiyin; Zhang, Huiqin; Zheng, Lei; Acosta, Yaritza; Hsu, Tsung-Ta D

    2017-11-01

    Although ferrate(VI) has long been recognized as a multi-purpose treatment agent, previous investigations regarding ferrate(VI) for addressing harmful algal blooms (HABs) impacts in drinking water treatment only focused on a single HAB pollutant (e.g. algal cells or algal toxins). Moreover, the performance of ferrate(VI)-driven coagulation was poorly investigated in comparison with ferrate(VI) oxidation, though it has been widely acknowledged as a major ferrate(VI) treatment mechanism. We herein reported ferrate(VI) as an emerging agent for simultaneous and effective removal of algal cells and toxins in a simulated HAB-impacted water. Ferrate(VI)-driven oxidation enabled algal cell inactivation and toxin decomposition. Subsequently, Fe(III) from ferrate(VI) reduction initiated an in-situ coagulation for cell aggregation. Cell viability (initial 4.26 × 10(4) cells/mL at pH 5.5 and 5.16 × 10(4) cells/mL at pH 7.5) decreased to 0.0% at ≥ 7 mg/L Fe(VI) at pH 5.5 and 7.5, respectively. Cell density and turbidity were dramatically decreased at pH 5.5 once ferrate(VI) doses were beyond their respective threshold levels, which are defined as minimum effective iron doses (MEIDs). However, the particulate removal at pH 7.5 was poor, likely because the coagulation was principally driven by charge neutralization and a higher pH could not sufficiently lower the particle surface charge. Meanwhile, algal toxins (i.e., microcystins) of 3.98 μg/L could be substantially decomposed at either pH. And the greater degradation achieved at pH 5.5 was due to the higher reactivity of ferrate(VI) at the lower pH. This study represents the first step toward the ferrate(VI) application as a promising approach for addressing multiple HABs impacts for water treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Oxidation of manganese(II) with ferrate: Stoichiometry, kinetics, products and impact of organic carbon.

    Science.gov (United States)

    Goodwill, Joseph E; Mai, Xuyen; Jiang, Yanjun; Reckhow, David A; Tobiason, John E

    2016-09-01

    Manganese is a contaminant of concern for many drinking water utilities, and future regulation may be pending. An analysis of soluble manganese (Mn(II)) oxidation by ferrate (Fe(VI)) was executed at the bench-scale, in a laboratory matrix, both with and without the presence of natural organic matter (NOM) and at two different pH values, 6.2 and 7.5. In the matrix without NOM, the oxidation of Mn(II) by Fe(VI) followed a stoichiometry of 2 mol Fe(VI) to 3 mol Mn(II). The presence of NOM did not significantly affect the stoichiometry of the oxidation reaction, indicating relative selectivity of Fe(VI) for Mn(II). The size distribution of resulting particles included significant amounts of nanoparticles. Resulting manganese oxide particles were confirmed to be MnO2 via X-ray photoelectron spectroscopy. The rate of the Mn(II) oxidation reaction was fast relative to typical time scales in drinking water treatment, with an estimated second order rate constant of approximately 1 × 10(4) M(-1) s(-1) at pH 9.2 and > 9 × 10(4) M(-1) s(-1) at pH 6.2. In general, ferrate is a potential option for Mn(II) oxidation in water treatment.

  6. Investigation of electrochemical synthesis of ferrate, Part I: Electrochemical behavior of iron and its several alloys in concentrated alkaline solutions

    Directory of Open Access Journals (Sweden)

    Čekerevac Milan I.

    2009-01-01

    Full Text Available In recent years, considerable attention has been paid to various applications of Fe(VI due to its unique properties such as oxidizing power, selective reactivity, stability of the salt, and non-toxic decomposition by-products of ferric ion. In environmental remediation processes, Fe(VI has been proposed as green oxidant, coagulant, disinfectant, and antifoulant. Therefore, it is considered as a promising multi-purpose water treatment chemical. Fe(VI has also potential applications in electrochemical energy source, as 'green cathode'. The effectiveness of ferrate as a powerful oxidant in the entire pH range, and its use in environmental applications for the removal of wide range of contaminants has been well documented by several researchers. There is scientific evidence that ferrate can effectively remove arsenic, algae, viruses, pharmaceutical waste, and other toxic heavy metals. Although Fe(VI was first discovered in early eighteen century, detailed studies on physical and chemical properties of Fe(VI had to wait until efficient synthetic and analytical methods of Fe(VI were developed by Schreyer et al. in the 1950s. Actually, there have been developed three ways for the preparation of Fe(VI compounds : the wet oxidation of Fe(II and Fe(III compounds, the dry oxidation of the same, and the electrochemistry method, mainly based on the trans passive oxidation of iron. High purity ferrates Fe(VI can be generated when electrode of the pure iron metal or its alloys are anodized in concentrated alkaline solution. It is known that the efficiency of electrochemical process of Fe(VI production depends on many factors such as current density, composition of anode material, types of electrolyte etc. In this paper, the electrochemical synthesis of ferrate(VI solution by the anodic dissolution of iron and its alloys in concentrated water solution of NaOH and KOH is investigated. The process of transpassive dissolution of iron to ferrate(VI was studied by

  7. About specific features of the structure modulation in the Bi-ferrate compounds isostructural with Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Sedykh, V.; Shekhtman, V.Sh.; Smirnova, I.S.; Bagautdinov, B.Sh.; Suvorov, E.V.; Dubovitskii, A.V

    2003-07-15

    The single-crystalline specimens of the Fe-doped (5% {sup 57}Fe) Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (2212Cu) compound have been synthesized to compare the behavior of the structure modulation in Bi-cuprate and Bi-ferrate compounds. According to the Moessbauer data obtained, one can conclude that extra oxygen, related to the presence of Cu{sup 3+} in 2212Cu, is most probably arranged in the Ca layer rather than in the Bi layer, as was supposed in the model of extra oxygen. Based on the analysis of the experimental data we propose the explanation of the structure modulation in Bi compounds. Due to the mismatch between the internal perovskite block and the external BiO layers the structure of the Bi compounds is distorted. The Sr layer being boundary between these blocks probably is most distorted and stressed. We suppose that the different changes related to the modulation can occur just in this layer. The Bi excess, which is always present in Bi compounds (especially in single crystals), can be just the necessary condition at which the modulation appears. Extra oxygen in principle can be present in modulated structures. However, in our opinion, it only complements the influence of other factors and is not the driving force in the structure modulation.

  8. Decontamination effectiveness of ferric ferrocyanide and ammonium-ferric-cyano-ferrate in rats contaminated with radiocaesium

    Energy Technology Data Exchange (ETDEWEB)

    Kossakowski, S.; Dziura, A.; Grosicki, A. (Veterinary Research Inst., Pulawy (Poland). Lab. of Radiological Protection and Isotopic Investigations)

    1991-01-01

    The experiment was performed on 115 Wistar rats divided into 3 groups: I - the controls, which were administered i.g. with 14 kBq per rat with Cs-137 and the radioactivities of internal organs and muscles 16 samples were measured on days 1, 3 and 7; II - treated with ferric ferrocyanide (FF) or ammonium-ferric-cyano-ferrate (AFCF) on day 1 after the Cs-137 administration and therefore they followed the same procedure as the controls; III - treated with FF or AFCF 2-fold/day for 5 days and the organ radioactivities were measured on day 7. The results indicated that FF and AFCF increased the biological elimination of Cs-137, especially on days 1-3. The decontamination effectiveness of AFCF was higher than that of FF. The repeated treatment increased the decontamination effectiveness. (orig.).

  9. [Degradation of BPA in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation].

    Science.gov (United States)

    Li, Cong; Gao, Nai-Yun; Zhang, Ke-Jia

    2009-03-15

    The degradation of bispehnol A (BPA) in aqueous suspension by interaction of photocatalytic oxidation and ferrate (VI) oxidation was investigated under different conditions. The results indicate that the formation of Fe (V) and Fe (IV) is in the photoreduction of Fe (VI) by electron (e(cb)-) on the surface of TiO2. The oxidation efficiency of the photocatalytic oxidation in the presence of Fe (VI) is much greater than that without Fe (VI). In addition, the decomposition of Fe (VI) under different conditions was also investigated. The results indicate that the Fe (VI) reduction is enhanced by photocatalytic oxidation and the adsorption capacity of Fe (VI) at TiO2 surface decreases with pH increase. When the photocatalytic oxidation is used to degrade BPA, Fe (VI) could increase the degradation rate about 2.5 times.

  10. Calcium ferrite formation from the thermolysis of calcium tris (maleato) ferrate(III)

    Indian Academy of Sciences (India)

    B S Randhawa; Kamaljeet Sweety

    2000-08-01

    For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to 900°C and ferrite formation. Three consecutive decomposition steps leading to the formation of -Fe2O3 and calcium carbonate have been observed at various stages of thermolysis. In the final stage the ferrite, Ca2Fe2O5, is obtained as a result of solid state reaction between -Fe2O3 and calcium carbonate at 788°C, a temperature much lower than for ceramic method. The results have been compared with those of the oxalate precursor.

  11. Potassium ferrate [Fe(VI] does not mediate self-sterilization of a surrogate mars soil

    Directory of Open Access Journals (Sweden)

    Paszczynski Andrzej

    2003-03-01

    Full Text Available Abstract Background Martian soil is thought to be enriched with strong oxidants such as peroxides and/or iron in high oxidation states that might destroy biological materials. There is also a high flux of ultraviolet radiation at the surface of Mars. Thus, Mars may be inhospitable to life as we know it on Earth. We examined the hypothesis that if the soil of Mars contains ferrates [Fe(VI], the strongest of the proposed oxidizing species, and also is exposed to high fluxes of UV radiation, it will be self-sterilizing. Results Under ambient conditions (25°C, oxygen and water present K2FeO4 mixed into sand mineralized some reactive organic molecules to CO2, while less reactive compounds were not degraded. Dried endospores of Bacillus subtilis incubated in a Mars surrogate soil comprised of dry silica sand containing 20% by weight K2FeO4 and under conditions similar to those now on Mars (extreme desiccation, cold, and a CO2-dominated atmosphere were resistant to killing by the ferrate-enriched sand. Similar results were observed with permanganate. Spores in oxidant-enriched sand exposed to high fluxes of UV light were protected from the sporocidal activity of the radiation below about 5 mm depths. Conclusion Based on our data and previously published descriptions of ancient but dormant life forms on Earth, we suggest that if entities resembling bacterial endospores were produced at some point by life forms on Mars, they might still be present and viable, given appropriate germination conditions. Endospores delivered to Mars on spacecraft would possibly survive and potentially compromise life detection experiments.

  12. 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.

  13. Large Energy Storage Density and High Thermal Stability in a Highly Textured (111)-Oriented Pb0.8Ba0.2ZrO3 Relaxor Thin Film with the Coexistence of Antiferroelectric and Ferroelectric Phases.

    Science.gov (United States)

    Peng, Biaolin; Zhang, Qi; Li, Xing; Sun, Tieyu; Fan, Huiqing; Ke, Shanming; Ye, Mao; Wang, Yu; Lu, Wei; Niu, Hanben; Zeng, Xierong; Huang, Haitao

    2015-06-24

    A highly textured (111)-oriented Pb0.8Ba0.2ZrO3 (PBZ) relaxor thin film with the coexistence of antiferroelectric (AFE) and ferroelectric (FE) phases was prepared on a Pt/TiOx/SiO2/Si(100) substrate by using a sol-gel method. A large recoverable energy storage density of 40.18 J/cm(3) along with an efficiency of 64.1% was achieved at room temperature. Over a wide temperature range of 250 K (from room temperature to 523 K), the variation of the energy density is within 5%, indicating a high thermal stability. The high energy storage performance was endowed by a large dielectric breakdown strength, great relaxor dispersion, highly textured orientation, and the coexistence of FE and AFE phases. The PBZ thin film is believed to be an attractive material for applications in energy storage systems over a wide temperature range.

  14. Thickness and temperature dependence of the magnetodynamic damping of pulsed laser deposited La0.7Sr0.3MnO3 on (111)-oriented SrTiO3

    Science.gov (United States)

    Flovik, Vegard; Macià, Ferran; Lendínez, Sergi; Hernàndez, Joan Manel; Hallsteinsen, Ingrid; Tybell, Thomas; Wahlström, Erik

    2016-12-01

    We have investigated the magnetodynamic properties of La0.7Sr0.3MnO3 (LSMO) films of thickness 10, 15 and 30 nm grown on (111)-oriented SrTiO3 (STO) substrates by pulsed laser deposition. Ferromagnetic resonance (FMR) experiments were performed in the temperature range 100-300 K, and the magnetodynamic damping parameter α was extracted as a function of both film thickness and temperature. We found that the damping is lowest for the intermediate film thickness of 15 nm with α ≈ 2 ·10-3 , where α is relatively constant as a function of temperature well below the Curie temperature of the respective films.

  15. Recent Developments of Ferrate (VI) Salts as Cathode Meterial in High Capacity Batteries%铁(VI)酸盐正极材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    袁中直; 周震涛; 李伟善

    2002-01-01

      The ferrate (VI) salts that have Fe element in an unusual VI valence state may be one of the best choices of high-energy batteries' cathode material, because ferrates (VI) are capable of the three-electron reduction, their reduction and decomposition products are nontoxic and environment-benign. One and a half century after the K2FeO4 synthesis, the chemistry and electrochemistry remains relatively unknown because of the incorrect knowledge of ferrates (VI) instability. The studies of ferrates (VI) used as cathode have been renewed recently. Many achievements have been made after the Israeli scientist Dr. Stuart Licht published their results on Science magazine that the alkaline ferrate (VI)/Zn batteries can provide 50% higher capacity than conventional alkaline batteries. In this article, the reasons of ferrate (VI) salts’ instability, methods of avoiding ferrate (VI) salts' decomposition and influences of some modifiers such as SrTiO3, Co2O3,MnO2,In2O3,KMnO4, (CFx)n on electrochemical characteristics of ferrate (VI) cathode are reviewed.%  铁(VI)酸盐中的Fe具有不寻常的高价态+6价,可以进行3电子还原放电反应,其还原产物及分解产物无毒无害,具有新一代“绿色电池”的重要特征。铁(VI)酸盐合成一个半世纪以来,由于认为它不稳定至今其化学和电化学性质并不很清楚。直到1999年以色列科学家Licht博士在Science上发表研究结果表明铁(VI)酸盐/Zn电池可以获得比常规碱性电池多50%的容量,铁(VI)酸盐高能电池才又引起深入的研究。本文综述了近年来铁(VI)酸盐作为高能电池正极活性物质的研究进展,包括改善铁(VI)酸盐稳定性的方法、掺杂修饰(如SrTiO3, Co2O3,MnO2,In2O3,KMnO4,(CFx)n等)等改善铁(VI)酸盐正极电化学性能的技术等。

  16. Chalcogenide perovskites for photovoltaics.

    Science.gov (United States)

    Sun, Yi-Yang; Agiorgousis, Michael L; Zhang, Peihong; Zhang, Shengbai

    2015-01-14

    Chalcogenide perovskites are proposed for photovoltaic applications. The predicted band gaps of CaTiS3, BaZrS3, CaZrSe3, and CaHfSe3 with the distorted perovskite structure are within the optimal range for making single-junction solar cells. The predicted optical absorption properties of these materials are superior compared with other high-efficiency solar-cell materials. Possible replacement of the alkaline-earth cations by molecular cations, e.g., (NH3NH3)(2+), as in the organic-inorganic halide perovskites (e.g., CH3NH3PbI3), are also proposed and found to be stable. The chalcogenide perovskites provide promising candidates for addressing the challenging issues regarding halide perovskites such as instability in the presence of moisture and containing the toxic element Pb.

  17. Formation of disinfection by-products after pre-oxidation with chlorine dioxide or ferrate.

    Science.gov (United States)

    Yang, Xin; Guo, Wanhong; Zhang, Xing; Chen, Feng; Ye, Tingjin; Liu, Wei

    2013-10-01

    The effect of pre-oxidation with chlorine dioxide (ClO2) or ferrate (Fe(VI)) on the formation of disinfection by-products (DBPs) during chlorination or chloramination was tested with natural waters from 12 sources (9 surface waters, 1 groundwater, and 2 wastewater effluents). DBPs investigated included trihalomethanes (THM), chloral hydrate (CH), haloketones (HK), haloacetonitriles (HAN) and trichloronitromethane (TCNM), chlorite and chlorate. Chlorite and chlorate were found in the ClO2-treated waters. Application of 1 mg/L ClO2 ahead of chlorination reduced the formation potential for THM by up to 45% and the formation of HK, HAN and TCNM in most of the samples. The CH formation results were mixed. The formation of CH and HK was enhanced with low doses of Fe(VI) (1 mg/L as Fe), but was greatly reduced at higher doses (20 mg/L Fe). Fe(VI) reduced the formation of THM, HAN and TCNM in most of the samples. Reduced potential for the formation of NDMA was observed in most of the samples after both ClO2 and Fe(VI) pre-oxidation.

  18. Comparison between ozone and ferrate in oxidising geosmin and 2-MIB in water.

    Science.gov (United States)

    Park, G; Yu, M; Go, J; Kim, E; Kim, H

    2007-01-01

    Among the chemicals causing taste and odour (T&O) in drinking water, the most commonly identified and problematic ones are geosmin and 2-MIB (2-methylisoborneol). Since the reported odour thresholds of geosmin and 2-MIB are as low as 4 and 8.5 ng/L, respectively, they are not readily removed by conventional water treatment processes. In this study, ozone (O3) and ferrate (Fe(VI)) were applied to oxidise geosmin and 2-MIB. Their performances were compared in terms of removal efficiency of geosmin and 2-MIB. In the case of O3, removal efficiency of geosmin and 2-MIB ozonation at different initial O3 doses, H2O2/O3 ratios and water temperatures were evaluated. The oxidation rates of geosmin and 2-MIB by Fe(VI) were measured within pH 6-8. The effect of H2O2 addition was also evaluated. In summary, O3, especially with H2O2, could almost completely oxidise geosmin and 2-MIB, while Fe(VI) could not oxidise them more than 25% at any pH that was considered in this study. This was attributed to the structure of the organics and high reaction selectivity of Fe(VI). Further study should be conducted to find the reason of inhibition of oxidation by Fe(VI).

  19. Preparation and application of sustained release microcapsules of potassium ferrate(VI) for dinitro butyl phenol (DNBP) wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huilong, E-mail: davidwang_71@yahoo.com.cn [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China); Liu Shuqin [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China); Zhang Xiuyan [Dalian Fishery Technical Extension Center, Dalian 116023 (China)

    2009-09-30

    The encapsulated potassium ferrate(VI) (K{sub 2}FeO{sub 4}) samples were successfully prepared by phase separation method in organic solvents. The ethyl cellulose and paraffin were selected for the microcapsule wall materials (WM). The as prepared microcapsules were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The stability can be enhanced greatly when ferrate(VI) was encapsulated in the microcapsules with a mass ratio of Fe(VI):WM in the range of 1:1-1:3 for the same conserved time in air compared for pure K{sub 2}FeO{sub 4}. The sustained release behavior of the microcapsules with different Fe(VI):WM mass ratios in 8.0 M KOH solution was also investigated. The results indicated that the Fe(VI) release was reduced with increase of Fe(VI):WM mass ratios from 1:1 to 1:3. The release kinetics of the microcapsules is found to obey Ritger-Peppas equation. The prepared Fe(VI) microcapsules has been used for the removal of a typical alkyl dinitro phenol compound, 2-sec-butyl-4,6-dinitrophenol (DNBP), from aqueous solution. The effect of pH, microcapsule concentration and reaction time was studied thoroughly. The optimal pH for DNBP degradation was 6.5, and at this pH and a microcapsule concentration of 1.2 g/L, approximately 93% of the DNBP was degraded after 80 min. The encapsulated ferrate(VI) samples were found to be very effective in the decolorization and COD reduction of real wastewater from DNBP manufacturing. Thus, this study showed the feasible and potential use of encapsulated Fe(VI) samples in degradation of various toxic organic contaminants and industrial effluents.

  20. Ferrates:Green Oxidants and Coagulants in Water Treatment%高铁酸盐:一种绿色的多功能水处理剂

    Institute of Scientific and Technical Information of China (English)

    王东升; 李文涛; 杨晓芳; 安广宇

    2016-01-01

    多种新型污染物和微生物污染等问题的出现,导致地表水水质复杂多变,传统的水处理药剂和处理方式已无法满足人们对饮用水处理的需求。高铁酸盐作为一种新型水处理试剂,同时具备优良的氧化性和混凝性,而且不会引起二次污染,是一种可大力开发的绿色试剂。本文综述了高铁酸盐净水剂的制备与表征分析方法,及其用于水处理对重金属、新型污染物和微生物等去除的作用机制。目前,有关高铁酸盐用于有机污染物去除的混凝和氧化去除协同作用的研究尚不多见,高铁酸盐的氧化-混凝协同特性尚未被充分开发。本文以此为重点进行了讨论,并对高铁酸盐净水剂的应用进行了展望。%The rise of emerging contaminants and microorganisms causes the complexity of drinking water quality and brings a gap between peoples demand and water treatment efficiency using conventional treatment reagents and techniques .Ferrate is an effective and multi-functional green water purification material , which shows both good oxidation and coagulation ability without secondary pollution .This paper reviews the removal mechanism of contaminants including heavy metal ions , emerging contaminants and microorganisms by ferrate . At present , the investigation of ferrates oxidation and coagulation cooperative effect is insufficient and the application of ferrates in water treatment has not been fully developed . Therefore , the oxidation and coagulation cooperative effect of ferrates is emphatically discussed to direct the application of ferrates in water treatment.Finally, the prospect of application of ferrates in water treatment is commented .

  1. High-temperature large-gap quantum anomalous Hall insulating state in ultrathin double perovskite films

    Science.gov (United States)

    Baidya, Santu; Waghmare, Umesh V.; Paramekanti, Arun; Saha-Dasgupta, Tanusri

    2016-10-01

    Towards the goal of realizing topological phases in thin films of correlated oxide and heterostructures, we propose here a quantum anomalous Hall insulator (QAHI) in ultrathin films of double perovskites based on mixed 3 d -5 d or 3 d -4 d transition-metal ions, grown along the [111] direction. Considering the specific case of ultrathin Ba2FeReO6 , we present a theoretical analysis of an effective Hamiltonian derived from first principles. We establish that a strong spin-orbit coupling at the Re site, t2 g symmetry of the low-energy d bands, polarity of its [111] orientation of perovskite structure, and mixed 3 d -5 d chemistry results in room temperature magnetism with a robust QAHI state of Chern number C =1 and a large band gap. We uncover and highlight a nonrelativistic orbital Rashba-type effect in addition to the spin-orbit coupling, that governs this QAHI state. With a band gap of ˜100 meV in electronic structure and magnetic transition temperature Tc˜300 K estimated by Monte Carlo simulations, our finding of the QAHI state in ultrathin Ba2FeReO6 is expected to stimulate experimental verification along with possible practical applications of its dissipationless edge currents.

  2. Ferroelectric ultrathin perovskite films

    Science.gov (United States)

    Rappe, Andrew M; Kolpak, Alexie Michelle

    2013-12-10

    Disclosed herein are perovskite ferroelectric thin-film. Also disclosed are methods of controlling the properties of ferroelectric thin films. These films can be used in a variety materials and devices, such as catalysts and storage media, respectively.

  3. Perovskites and garnets

    Energy Technology Data Exchange (ETDEWEB)

    Khattak, C.P.; Wang, F.F.Y.

    1976-01-01

    The preparation and properties of perovskites and garnets are reviewed. Data and information are presented on crystal chemistry, crystal structure, phase equilibria, electrical properties, optical properties, and mechanical properties. (JRD)

  4. An iron-based beverage, HydroFerrate fluid (MRN-100, alleviates oxidative stress in murine lymphocytes in vitro

    Directory of Open Access Journals (Sweden)

    Gollapudi Sastry

    2009-05-01

    Full Text Available Abstract Background Several studies have examined the correlation between iron oxidation and H2O2 degradation. The present study was carried out to examine the protective effects of MRN-100 against stress-induced apoptosis in murine splenic cells in vitro. MRN-100, or HydroFerrate fluid, is an iron-based beverage composed of bivalent and trivalent ferrates. Methods Splenic lymphocytes from mice were cultured in the presence or absence of MRN-100 for 2 hrs and were subsequently exposed to hydrogen peroxide (H2O2 at a concentration of 25 μM for 14 hrs. Percent cell death was examined by flow cytometry and trypan blue exclusion. The effect of MRN-100 on Bcl-2 and Bax protein levels was determined by Western blot. Results Results show, as expected, that culture of splenic cells with H2O2 alone results in a significant increase in cell death (apoptosis as compared to control (CM cells. In contrast, pre-treatment of cells with MRN-100 followed by H2O2 treatment results in significantly reduced levels of apoptosis. In addition, MRN-100 partially prevents H2O2-induced down-regulation of the anti-apoptotic molecule Bcl-2 and upregulation of the pro-apoptotic molecule Bax. Conclusion Our findings suggest that MRN-100 may offer a protective effect against oxidative stress-induced apoptosis in lymphocytes.

  5. Preparation and Application of Sustained-Release Potassium Ferrate(VI

    Directory of Open Access Journals (Sweden)

    Xuan Xu

    2014-01-01

    Full Text Available In this study, a composite system for the sustained release of potassium ferrate(VI (sustained-release K2FeO4 was prepared and applied for water treatment. The objective of this research was to maximize the effectiveness of K2FeO4 for water treatment by enhancing its stability using diatomite. The sustained-release K2FeO4 was characterized using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results indicated that no new crystal phase was formed during the preparation and some K2FeO4 crystals entered the pores of the diatomite. From K2FeO4 release experiments, we found that the decomposition rate of K2FeO4 was obviously decreased, which greatly improved the contact rate between released K2FeO4 and pollutants. Via degradation of methyl orange, which was used as a model pollutant, the influential factor of K2FeO4 content within the complete sustained-release K2FeO4 system was studied. The optimal K2FeO4 content within the sustained-release K2FeO4 system was approximately 70%. In natural water samples, sustained-release K2FeO4 at a dosage of 0.06 g/L and with a reaction time of 20 minutes removed 36.84% of soluble microbial products and 17.03% of simple aromatic proteins, and these removal rates were better than those observed after traditional chlorine disinfection.

  6. Degradation of fluoroquinolone antibiotics by ferrate(VI): Effects of water constituents and oxidized products.

    Science.gov (United States)

    Feng, Mingbao; Wang, Xinghao; Chen, Jing; Qu, Ruijuan; Sui, Yunxia; Cizmas, Leslie; Wang, Zunyao; Sharma, Virender K

    2016-10-15

    The degradation of five fluoroquinolone (FQ) antibiotics (flumequine (FLU), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (OFL) and marbofloxacin (MAR)) by ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) was examined to demonstrate the potential of this iron-based chemical oxidant to treat antibiotics in water. Experiments were conducted at different molar ratios of Fe(VI) to FQs at pH 7.0. All FQs, except FLU, were degraded within 2 min at [Fe(VI)]:[FQ] ≤ 20.0. Multiple additions of Fe(VI) improved the degradation efficiency, and provided greater degradation than a single addition of Fe(VI). The effects of anions, cations, and humic acid (HA), usually present in source waters and wastewaters, on the removal of FLU were investigated. Anions (Cl(-), SO4(2-), NO3(-), and HCO3(-)) and monovalent cations (Na(+) and K(+)) had no influence on the removal of FLU. However, multivalent cations (Ca(2+), Mg(2+), Cu(2+), and Fe(3+)) in water decreased the efficiency of FLU removal by Fe(VI). An increase in the ionic strength of the solution, and the presence of HA in the water, also decreased the percentage of FLU removed by Fe(VI). Experiments on the removal of selected FQs, present as co-existing antibiotics in pure water, river water, synthetic water and wastewater, were also conducted to demonstrate the practical application of Fe(VI) to remove the antibiotics during water treatment. The seventeen oxidized products (OPs) of FLU were identified using solid phase extraction-liquid chromatography-high-resolution mass spectrometry. The reaction pathways are proposed, and are theoretically confirmed by molecular orbital calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The Handheld Library: Developments at the Rector Gabriel Ferraté Library, UPC

    Directory of Open Access Journals (Sweden)

    Beatriz Benítez Juan

    2011-10-01

    Full Text Available The purpose of this paper is to highlight the mobile services developed by the Rector Gabriel Ferraté Library (BRGF of the Universitat Politècnica de Catalunya (UPC-Barcelona Tech in Barcelona, Spain. We hope this paper will be of use to other libraries exploring new technologies for communicating and delivering their services to users at a time when mobile services are an emerging topic in librarianship and information science literature. By setting out the successive steps involved in the as yet unfinished process of building our mobile services portfolio, we aim to offer a detailed picture of the mobile services and features offered by a university library from a case study perspective. The main topics to be discussed include: The BRGF’s mobile website, including the information available, its interactive capabilities and the services it provides to its users. The mobile-friendly version of UP Commons(the UPC Library Service’s institutional repositories. The UPC Library Service’s mobile OPAC. The mobile version of u-win(BRGF’s videogame service. The use of QR codes to deliver information to mobile devices. Text message notifications. Additional topics for discussion include: The library’s organisation and the organisational concepts that underpin and make possible its technological developments (including mobile. BRGF’s concern regarding the reduction of investment in the development of mobile services. The criteria and tools used to guide the library’s decisions regarding the design and orientation of current and future mobile services. How mobile services can help to improve the image of the library as a leading technology site. Selected mobile features that BRGF plans to offer in the near future. Ultimately, this paper aims to delineate the effectiveness and potential of delivering library services by the preferred means of communication of a new generation of students and teachers.

  8. Synthesis and crystal structure of new K and Rb selenido/tellurido ferrate cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stueble, Pirmin; Berroth, Angela; Roehr, Caroline [Freiburg Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-08-01

    In the course of a systematic study of alkali iron chalcogenido salts containing clusters [Fe{sub 4}Q{sub 8}] a series of new mixed-valent potassium and rubidium selenido and tellurido ferrates(II/III) was synthesized by carefully heating the pure elements enclosed in sample tubes under an argon atmosphere up to maximum temperatures of 800-900 C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The mixed-valent Fe{sup II/III} tellurido ferrates A{sub 7}[Fe{sub 4}Te{sub 8}] form three different structure types. All structures contain tetramers of four edge sharing [FeTe{sub 4}] tetrahedra, which are connected by common edges to form only slightly distorted tetrahedral [Fe{sub 4}Te{sub 8}]{sup 7-} anions ('stella quadrangula') with a [Fe{sub 4}Te{sub 4}] cubane core. In all cases, these anions are surrounded by 26 alkali cations, which are located at the eight corners and the midpoints of the six faces and 12 edges of a cube. The three crystal structures can thus be described by three different packings of cuboid moieties: The monoclinic rubidium compound Rb{sub 7}[Fe{sub 4}Te{sub 8}] (space group C2/c, a = 2000.16(7), b = 897.79(3), c = 1768.12(6) pm, β = 117.4995(10) , Z = 4, R1 = 0.0296) is isotypic to the known cesium tellurido and sulfido ferrates Cs{sub 7}[Fe{sub 4}(S/Te){sub 8}]. Depending on the temperature, K{sub 7}[Fe{sub 4}Te{sub 8}] forms two different but closely related new structure types: The tetragonal r.t. modification (space group P4{sub 2}/nmc, a = 1222.25(14), c = 872.1(2) pm, Z = 2, R1 = 0.0583) crystallizes in a supergroup of the orthorhombic l.t. (100 K) form (space group Pbcn, a = 1715.5, b = 866.76(3), c = 1715.50(7) pm, Z = 4, R1 = 0.0160). In all structures, the cluster centered cubes are stacked to form columns along the short (∼ 870 pm) axis. These columns are themselves densely packed with 4 (both K compounds) and 6 (A = Rb) adjacent face-sharing columns. According to these

  9. Pyroelectricity and Spontaneous Polarization in [111] Oriented 0.955 Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    SHEN Ming-Rong; YAO Dong-Lai; CAO Wen-Wu

    2005-01-01

    @@ We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0. 955 Pb(Zn1/3Nb2/3)O3-0.045 PbTiO3 (PZN-4.5%PT) single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30℃ increases abruptly from 14μC/cm2 for a poling field of 0.06kV/cm to 29.5μC/cm2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm2 for poling fields beyond 0.55 kV/cm.

  10. 3D imaging using X-Ray tomography and SEM combined FIB to study non isothermal creep damage of (111) oriented samples of γ / γ ′ nickel base single crystal superalloy MC2

    KAUST Repository

    Jouiad, Mustapha

    2012-01-01

    An unprecedented investigation consisting of the association of X-Ray tomography and Scanning Electron Microscopy combined with Focus Ion Beam (SEM-FIB) is conducted to perform a 3D reconstruction imaging. These techniques are applied to study the non-isothermal creep behavior of close (111) oriented samples of MC2 nickel base superalloys single crystal. The issue here is to develop a strategy to come out with the 3D rafting of γ\\' particles and its interaction whether with dislocation structures or/and with the preexisting voids. This characterization is uncommonly performed away from the conventional studied orientation [001] in order to feed the viscoplastic modeling leading to its improvement by taking into account the crystal anisotropy. The creep tests were performed at two different conditions: classical isothermal tests at 1050°C under 140 MPa and a non isothermal creep test consisting of one overheating at 1200°C and 30 seconds dwell time during the isothermal creep life. The X-Ray tomography shows a great deformation heterogeneity that is pronounced for the non-isothermal tested samples. This deformation localization seems to be linked to the preexisting voids. Nevertheless, for both tested samples, the voids coalescence is the precursor of the observed damage leading to failure. SEM-FIB investigation by means of slice and view technique gives 3D views of the rafted γ\\' particles and shows that γ corridors evolution seems to be the main creep rate controlling parameter. © 2012 Trans Tech Publications, Switzerland.

  11. PEROVSKITE SOLAR CELLS (REVIEW ARTICLE)

    OpenAIRE

    Benli, Deniz Ahmet

    2015-01-01

    A solar cell is a device that converts sunlight into electricity. There are different types of solar cells but this report mainly focuses on a type of new generation solar cell that has the name organo-metal halide perovskite, shortly perovskite solar cells. In this respect, the efficiency of power conversion is taken into account to replace the dominancy of traditional and second generation solar cell fields by perovskite solar cells. Perovskite solar cell is a type of solar cell including a...

  12. Perovskite photonic sources

    Science.gov (United States)

    Sutherland, Brandon R.; Sargent, Edward H.

    2016-05-01

    The field of solution-processed semiconductors has made great strides; however, it has yet to enable electrically driven lasers. To achieve this goal, improved materials are required that combine efficient (>50% quantum yield) radiative recombination under high injection, large and balanced charge-carrier mobilities in excess of 10 cm2 V-1 s-1, free-carrier densities greater than 1017 cm-3 and gain coefficients exceeding 104 cm-1. Solid-state perovskites are -- in addition to galvanizing the field of solar electricity -- showing great promise in photonic sources, and may be the answer to realizing solution-cast laser diodes. Here, we discuss the properties of perovskites that benefit light emission, review recent progress in perovskite electroluminescent diodes and optically pumped lasers, and examine the remaining challenges in achieving continuous-wave and electrically driven lasing.

  13. Electrospun Perovskite Nanofibers

    Science.gov (United States)

    Chen, Dongsheng; Zhu, Yanyan

    2017-02-01

    CH3NH3PbI3 perovskite nanofibers were synthesized by versatile electrospinning techniques. The synthetic CH3NH3PbI3 nanofibers were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and photoluminescence. As counter electrodes, the synthesized nanofibers increased the performance of the dye-sensitized solar cells from 1.58 to 2.09%. This improvement was attributed to the enhanced smoothness and efficiency of the electron transport path. Thus, CH3NH3PbI3 perovskites nanofibers are potential alternative to platinum counter electrodes in dye-sensitized solar cells.

  14. Synergistic effect of aqueous removal of fluoroquinolones by a combined use of peroxymonosulfate and ferrate(VI).

    Science.gov (United States)

    Feng, Mingbao; Cizmas, Leslie; Wang, Zunyao; Sharma, Virender K

    2017-06-01

    This paper examines for the first time the combined use of ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) with peroxymonosulfate (PMS) to oxidize four fluoroquinolones (FQs) (flumequine (FLU), enrofloxacin (ENR), marbofloxacin (MAR), and ofloxacin (OFL)) at pH 7.0 and 25.0 °C. The results demonstrate that a combination of PMS and Fe(VI) synergistically enhance removal of FQs compared to the removal seen with either PMS or Fe(VI) alone. The oxidized products (OPs) of the reaction of FLU with the PMS-Fe(VI) system, identified by liquid chromatography high-resolution mass spectrometry (LC-HRMS) techniques, showed transformation products resulted from hydroxylation, ring cleavage, and de-fluorination processes. Thus, the combination of PMS and Fe(VI) can be developed as an innovative oxidative technology to remove contaminants from water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. La Relación entre filosofía y ciencia en la obra de José Ferrater Mora

    OpenAIRE

    2015-01-01

    Esta tesis trata de la relación entre filosofía y ciencia en el pensamiento de José Ferrater Mora. El método empleado para analizar esta relación filosofía-ciencia es de carácter internalista y tiene en cuenta el método integracionista, creado y empleado por el mismo Ferrater. La línea guía del análisis crítico llevado a cabo consiste en buscar las ideas e influencias de la ciencia diseminadas en su obra y aislar tanto como sea posible este aspecto, dándole unidad al tema de la relación filos...

  16. La relación entre filosofía y ciencia en la obra de José Ferrater Mora

    OpenAIRE

    2015-01-01

    Esta tesis trata de la relación entre filosofía y ciencia en el pensamiento de José Ferrater Mora. El método empleado para analizar esta relación filosofía-ciencia es de carácter internalista y tiene en cuenta el método integracionista, creado y empleado por el mismo Ferrater. La línea guía del análisis crítico llevado a cabo consiste en buscar las ideas e influencias de la ciencia diseminadas en su obra y aislar tanto como sea posible este aspecto, dándole unidad al tema de la relación filos...

  17. Kinetics of membrane damage to high (HNA) and low (LNA) nucleic acid bacterial clusters in drinking water by ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate.

    Science.gov (United States)

    Ramseier, Maaike K; von Gunten, Urs; Freihofer, Pietro; Hammes, Frederik

    2011-01-01

    Drinking water was treated with ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate to investigate the kinetics of membrane damage of native drinking water bacterial cells. Membrane damage was measured by flow cytometry using a combination of SYBR Green I and propidium iodide (SGI+PI) staining as indicator for cells with permeabilized membranes and SGI alone to measure total cell concentration. SGI+PI staining revealed that the cells were permeabilized upon relatively low oxidant exposures of all tested oxidants without a detectable lag phase. However, only ozonation resulted in a decrease of the total cell concentrations for the investigated reaction times. Rate constants for the membrane damage reaction varied over seven orders of magnitude in the following order: ozone > chlorine > chlorine dioxide ≈ ferrate > permanganate > chloramine. The rate constants were compared to literature data and were in general smaller than previously measured rate constants. This confirmed that membrane integrity is a conservative and therefore safe parameter for disinfection control. Interestingly, the cell membranes of high nucleic acid (HNA) content bacteria were damaged much faster than those of low nucleic acid (LNA) content bacteria during treatment with chlorine dioxide and permanganate. However, only small differences were observed during treatment with chlorine and chloramine, and no difference was observed for ferrate treatment. Based on the different reactivity of these oxidants it was suggested that HNA and LNA bacterial cell membranes have a different chemical constitution. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. High Performance Perovskite Solar Cells.

    Science.gov (United States)

    Tong, Xin; Lin, Feng; Wu, Jiang; Wang, Zhiming M

    2016-05-01

    Perovskite solar cells fabricated from organometal halide light harvesters have captured significant attention due to their tremendously low device costs as well as unprecedented rapid progress on power conversion efficiency (PCE). A certified PCE of 20.1% was achieved in late 2014 following the first study of long-term stable all-solid-state perovskite solar cell with a PCE of 9.7% in 2012, showing their promising potential towards future cost-effective and high performance solar cells. Here, notable achievements of primary device configuration involving perovskite layer, hole-transporting materials (HTMs) and electron-transporting materials (ETMs) are reviewed. Numerous strategies for enhancing photovoltaic parameters of perovskite solar cells, including morphology and crystallization control of perovskite layer, HTMs design and ETMs modifications are discussed in detail. In addition, perovskite solar cells outside of HTMs and ETMs are mentioned as well, providing guidelines for further simplification of device processing and hence cost reduction.

  19. 高铁氧化技术在环境污染治理中的应用及研究进展%The Application and Advances of Potassium Ferrate in Removal of Pollutents

    Institute of Scientific and Technical Information of China (English)

    马超

    2012-01-01

    Potassium ferrate technology has been paied more and more attention with advantage of itself.The article introduces the preparation of potassium ferrate and the mechanism of pollutants processing,discusses the main influence factors in the pollutants processing.It states the advances in hypHenated techniques.by combination of potassium ferrate and other treatment techniques.%高铁氧化技术在环境污染治理中因其自身所具有的优势而得到越来越多的重视,文章介绍了高铁盐在污染物处理的作用机理,讨论了高铁盐在处理污染物过程中主要影响因素。简述高铁氧化技术与其他处理技术协同作用的研究进展。

  20. Tunable perovskite microdisk lasers.

    Science.gov (United States)

    Sun, Wenzhao; Wang, Kaiyang; Gu, Zhiyuan; Xiao, Shumin; Song, Qinghai

    2016-04-28

    Perovskite microdisk lasers have been intensively studied recently. But their lasing properties are usually fixed once the devices are synthesized. Here, for the first time, we demonstrated the switchable and tunable perovskite microdisk lasers by surrounding them with 5CB liquid crystals. With the increase of the environmental temperature from 24 °C to 34 °C, the lasing wavelength slightly changed from 552.91 nm to 552.11 nm at the beginning and suddenly shifted to around 552.54 nm at T = 32 °C, where the phase transition of liquid crystals occurs. Our numerical calculation shows that the wavelength shift is caused by the changes of the refractive index of liquid crystals. More than tuning of the wavelength, a more dramatic wavelength transition from ∼554 nm to 550 nm has also been observed. This sudden transition is mainly induced by the reduction of scattering rather than the change in the refractive index when the liquid crystals are changed from the nematic phase to the isotropic phase. We believe that our research can shed light on the applications of perovskite optoelectronics.

  1. Crystallography and Chemistry of Perovskites

    OpenAIRE

    Johnsson, Mats; Lemmens, Peter

    2005-01-01

    Despite the simplicity of the original perovskite crystal structure, this family of compounds shows an enormous variety of structural modifications and variants. In the following, we will describe several examples of perovskites, their structural variants and discuss the implications of distortions and non-stoichiometry on their electronic and magnetic properties.

  2. Advances in Perovskite Solar Cells.

    Science.gov (United States)

    Zuo, Chuantian; Bolink, Henk J; Han, Hongwei; Huang, Jinsong; Cahen, David; Ding, Liming

    2016-07-01

    Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite-based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non-PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures. Many innovative device structures were developed, aiming at large-scale fabrication, reducing fabrication cost, enhancing the power conversion efficiency and thus broadening potential future applications. This review summarizes typical structures of perovskite solar cells and comments on novel device structures. The applications of perovskite solar cells are discussed.

  3. Multidimensional Perovskites: A Mixed Cation Approach Towards Ambient Stable and Tunable Perovskite Photovoltaics.

    Science.gov (United States)

    Koh, Teck Ming; Thirumal, Krishnamoorthy; Soo, Han Sen; Mathews, Nripan

    2016-09-22

    Although halide perovskites are able to deliver high power conversion efficiencies, their ambient stability still remains an obstacle for commercialization. Thus, promoting the ambient stability of perovskites has become a key research focus. In this review, we highlight the sources of instability in conventional 3 D perovskites, including water intercalation, ion migration, and thermal decomposition. Recently, the multidimensional perovskites approach has become one of the most promising strategies to enhance the stability of perovskites. As compared to pure 2 D perovskites, multidimensional perovskites typically possess more ideal band gaps, better charge transport, and lower exciton binding energy, which are essential for photovoltaic applications. The larger organic cations in multidimensional perovskites could also be more chemically stable at higher temperatures than the commonly used methylammonium cation. By combining 3 D and 2 D perovskites to form multidimensional perovskites, halide perovskite photovoltaics can attain both high efficiency and increased stability.

  4. Methodologies for high efficiency perovskite solar cells.

    Science.gov (United States)

    Park, Nam-Gyu

    2016-01-01

    Since the report on long-term durable solid-state perovskite solar cell in 2012, perovskite solar cells based on lead halide perovskites having organic cations such as methylammonium CH3NH3PbI3 or formamidinium HC(NH2)2PbI3 have received great attention because of superb photovoltaic performance with power conversion efficiency exceeding 22 %. In this review, emergence of perovskite solar cell is briefly introduced. Since understanding fundamentals of light absorbers is directly related to their photovoltaic performance, opto-electronic properties of organo lead halide perovskites are investigated in order to provide insight into design of higher efficiency perovskite solar cells. Since the conversion efficiency of perovskite solar cell is found to depend significantly on perovskite film quality, methodologies for fabricating high quality perovskite films are particularly emphasized, including various solution-processes and vacuum deposition method.

  5. Methodologies for high efficiency perovskite solar cells

    Science.gov (United States)

    Park, Nam-Gyu

    2016-06-01

    Since the report on long-term durable solid-state perovskite solar cell in 2012, perovskite solar cells based on lead halide perovskites having organic cations such as methylammonium CH3NH3PbI3 or formamidinium HC(NH2)2PbI3 have received great attention because of superb photovoltaic performance with power conversion efficiency exceeding 22 %. In this review, emergence of perovskite solar cell is briefly introduced. Since understanding fundamentals of light absorbers is directly related to their photovoltaic performance, opto-electronic properties of organo lead halide perovskites are investigated in order to provide insight into design of higher efficiency perovskite solar cells. Since the conversion efficiency of perovskite solar cell is found to depend significantly on perovskite film quality, methodologies for fabricating high quality perovskite films are particularly emphasized, including various solution-processes and vacuum deposition method.

  6. Advances in Perovskite Solar Cells

    Science.gov (United States)

    Zuo, Chuantian; Bolink, Henk J.; Han, Hongwei; Huang, Jinsong

    2016-01-01

    Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite‐based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non‐PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures. Many innovative device structures were developed, aiming at large‐scale fabrication, reducing fabrication cost, enhancing the power conversion efficiency and thus broadening potential future applications. This review summarizes typical structures of perovskite solar cells and comments on novel device structures. The applications of perovskite solar cells are discussed.

  7. Perovskite photovoltaics: Slow recombination unveiled

    Science.gov (United States)

    Moser, Jacques-E.

    2017-01-01

    One of the most salient features of hybrid lead halide perovskites is the extended lifetime of their photogenerated charge carriers. This property has now been shown experimentally to originate from a slow, thermally activated recombination process.

  8. Perovskite solar cells: Stability lies at interfaces

    Science.gov (United States)

    Lira-Cantú, Mónica

    2017-07-01

    Perovskite solar cells are developing fast but their lifetimes must be extended. Now, large-area printed perovskite solar modules have been shown to be stable for more than 10,000 hours under continuous illumination.

  9. Photocatalysis: HI-time for perovskites

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard

    2017-01-01

    Organolead halide perovskite solar absorbers demonstrate high photovoltaic efficiencies but they are notorious for their intolerance to water. Now, methylammonium lead iodide perovskites are used to harvest solar energy — in water — via photocatalytic generation of hydrogen from solutions...

  10. Chalcogenide Perovskites for Solar Energy Harvesting

    Science.gov (United States)

    Perera, Samanthe

    Methylammonium Lead halide perovskites have recently emerged as a promising candidate for realizing high efficient low cost photovoltaic modules. Charge transport properties of the solution processed halide perovskites are comparable to some of the existing absorbers used in the current PV industry which require sophisticated processing techniques. Due to this simple processing required to achieve high efficiencies, halide perovskites have become an active field of research. As a result, perovskite solar cells are rapidly reaching towards theoretical efficiency limit of close to 30%. It's believed that ionicity inherent to perovskite materials is one of the contributing factors for the excellent charge transport properties of perovskites. Despite the growing interest for solar energy harvesting purposes, these halide perovskites have serious limitations such as toxicity and instability that need to be addressed in order to commercialize the solar cells incorporating them. This dissertation focuses on a new class of ionic semiconductors, chalcogenide perovskites for solar energy harvesting purposes. Coming from the family perovskites they are expected to have same excellent charge transport properties inherent to perovskites due to the ionicity. Inspired by few theoretical studies on chalcogenide perovskites, BaZrS3 and its Ti alloys were synthesized by sulfurizing the oxide counterpart. Structural characterizations have confirmed the predicted distorted perovskite phase. Optical characterizations have verified the direct band gap suitable for thin film single junction solar cells. Anion alloying was demonstrated by synthesizing oxysulfides with widely tunable band gap suitable for applications such as solid state lighting and sensing.

  11. Perovskite-perovskite tandem photovoltaics with optimized band gaps

    Science.gov (United States)

    Eperon, Giles E.; Leijtens, Tomas; Bush, Kevin A.; Prasanna, Rohit; Green, Thomas; Wang, Jacob Tse-Wei; McMeekin, David P.; Volonakis, George; Milot, Rebecca L.; May, Richard; Palmstrom, Axel; Slotcavage, Daniel J.; Belisle, Rebecca A.; Patel, Jay B.; Parrott, Elizabeth S.; Sutton, Rebecca J.; Ma, Wen; Moghadam, Farhad; Conings, Bert; Babayigit, Aslihan; Boyen, Hans-Gerd; Bent, Stacey; Giustino, Feliciano; Herz, Laura M.; Johnston, Michael B.; McGehee, Michael D.; Snaith, Henry J.

    2016-11-01

    We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable “all-perovskite” thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

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

    OpenAIRE

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

    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 s...

  13. Graded bandgap perovskite solar cells

    Science.gov (United States)

    Ergen, Onur; Gilbert, S. Matt; Pham, Thang; Turner, Sally J.; Tan, Mark Tian Zhi; Worsley, Marcus A.; Zettl, Alex

    2017-05-01

    Organic-inorganic halide perovskite materials have emerged as attractive alternatives to conventional solar cell building blocks. Their high light absorption coefficients and long diffusion lengths suggest high power conversion efficiencies, and indeed perovskite-based single bandgap and tandem solar cell designs have yielded impressive performances. One approach to further enhance solar spectrum utilization is the graded bandgap, but this has not been previously achieved for perovskites. In this study, we demonstrate graded bandgap perovskite solar cells with steady-state conversion efficiencies averaging 18.4%, with a best of 21.7%, all without reflective coatings. An analysis of the experimental data yields high fill factors of ~75% and high short-circuit current densities up to 42.1 mA cm-2. The cells are based on an architecture of two perovskite layers (CH3NH3SnI3 and CH3NH3PbI3-xBrx), incorporating GaN, monolayer hexagonal boron nitride, and graphene aerogel.

  14. Perovskite solar cells: an emerging photovoltaic technology

    Directory of Open Access Journals (Sweden)

    Nam-Gyu Park

    2015-03-01

    Full Text Available Perovskite solar cells based on organometal halides represent an emerging photovoltaic technology. Perovskite solar cells stem from dye-sensitized solar cells. In a liquid-based dye-sensitized solar cell structure, the adsorption of methylammonium lead halide perovskite on a nanocrystalline TiO2 surface produces a photocurrent with a power conversion efficiency (PCE of around 3–4%, as first discovered in 2009. The PCE was doubled after 2 years by optimizing the perovskite coating conditions. However, the liquid-based perovskite solar cell receives little attention because of its stability issues, including instant dissolution of the perovskite in a liquid electrolyte. A long-term, stable, and high efficiency (∼10% perovskite solar cell was developed in 2012 by substituting the solid hole conductor with a liquid electrolyte. Efficiencies have quickly risen to 18% in just 2 years. Since PCE values over 20% are realistically anticipated with the use of cheap organometal halide perovskite materials, perovskite solar cells are a promising photovoltaic technology. In this review, the opto-electronic properties of perovskite materials and recent progresses in perovskite solar cells are described. In addition, comments on the issues to current and future challenges are mentioned.

  15. 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.

  16. 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

  17. Magnetoresistance stories of double perovskites

    Indian Academy of Sciences (India)

    Abhishek Nag; Sugata Ray

    2015-06-01

    Tunnelling magnetoresistance (TMR) in polycrystalline double perovskites has been an important research topic for more than a decade now, where the nature of the insulating tunnel barrier is the core issue of debate. Other than the nonmagnetic grain boundaries as conventional tunnel barriers, intragrain magnetic antiphase boundaries (APB) as well as magnetically frustrated grain surfaces have also been proposed to act as tunnel barriers in Sr2FeMoO6. In this review, the present state of the debate has been discussed briefly and how the physical state of the material can affect the magnetoresistance signal of double perovskites in many different ways has been pointed out.

  18. Systems and methods for scalable perovskite device fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinsong; Dong, Qingfeng; Sao, Yuchuan

    2017-02-28

    Continuous processes for fabricating a perovskite device are described that include using a doctor blade for continuously forming a perovskite layer and using a conductive tape lamination process to form an anode or a cathode layer on the perovskite device.

  19. Monolithic Perovskite Silicon Tandem Solar Cells with Advanced Optics

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, Jan C.; Bett, Alexander J.; Bivour, Martin; Blasi, Benedikt; Eisenlohr, Johannes; Kohlstadt, Markus; Lee, Seunghun; Mastroianni, Simone; Mundt, Laura; Mundus, Markus; Ndione, Paul; Reichel, Christian; Schubert, Martin; Schulze, Patricia S.; Tucher, Nico; Veit, Clemens; Veurman, Welmoed; Wienands, Karl; Winkler, Kristina; Wurfel, Uli; Glunz, Stefan W.; Hermle, Martin

    2016-11-14

    For high efficiency monolithic perovskite silicon tandem solar cells, we develop low-temperature processes for the perovskite top cell, rear-side light trapping, optimized perovskite growth, transparent contacts and adapted characterization methods.

  20. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

  1. Ferroelectric Graphene-Perovskite Interfaces.

    Science.gov (United States)

    Volonakis, George; Giustino, Feliciano

    2015-07-02

    Owing to their record-breaking energy conversion efficiencies, hybrid organometallic perovskites have emerged as the most promising light absorbers and ambipolar carrier transporters for solution-processable solar cells. Simultaneously, due to its exceptional electron mobility, graphene represents a prominent candidate for replacing transparent conducting oxides. Thus, it is possible that combining these wonder materials may propel the efficiency toward the Schokley-Queisser limit. Here, using first-principles calculations on graphene-CH3NH3PbI3 interfaces, we find that graphene suppresses the octahedral tilt in the very first perovskite monolayer, leading to a nanoscale ferroelectric distortion with a permanent polarization of 3 mC/m(2). This interfacial ferroelectricity drives electron extraction from the perovskite and hinders electron-hole recombination by keeping the electrons and holes separated. The interfacial ferroelectricity identified here simply results from the interplay between graphene's planar structure and CH3NH3PbI3's octahedral connectivity; therefore, this mechanism may be effective in a much broader class of perovskites, with potential applications in photovoltaics and photocatalysis.

  2. Common features of gallium perovskites

    NARCIS (Netherlands)

    Aleksiyko, R; Berkowski, M; Byszewski, P; Dabrowski, B; Diduszko, R; Fink-Finowicki, J; Vasylechko, LO

    2001-01-01

    The Czochralski and floating zone methods have been used to grow single crystals of gallium perovskites solid solutions with rare earth elements La, Pr, Nd, Sm and with Sr. The structure of the crystals has been investigated by powder X-ray, synchrotron radiation and neutron diffraction methods over

  3. Vibrational spectra of ordered perovskites

    NARCIS (Netherlands)

    Corsmit, A.F.; Hoefdraad, H.E.; Blasse, G.

    1972-01-01

    The vibrational spectra of the molecular M6+O6 (M = Mo, Te, W) group in ordered perovskites of the type Ba2M2+M6+O6 are reported. These groups have symmetry Oh, whereas their site symmetry is also Oh. An assignment of the internal vibrations is presented.

  4. perovskite up to 55 GPa

    Science.gov (United States)

    Gréaux, Steeve; Andrault, Denis; Gautron, Laurent; Bolfan-Casanova, Nathalie; Mezouar, Mohamed

    2014-06-01

    Compressibility of perovskite-structured Ca3Al2Si3O12 grossular (GrPv) was investigated at high pressure and high temperature by means of angle-dispersive powder X-ray diffraction using a laser-heated diamond anvil cell. We observed the Pbnm orthorhombic distortion for the pure phase above 50 GPa, whereas below this pressure, Al-bearing CaSiO3 perovskite coexists with an excess of corundum. GrPv has a bulk modulus ( K 0 = 229 ± 5 GPa; fixed to 4) almost similar to that reported for pure CaSiO3 perovskite. Its unit-cell volume extrapolated to ambient conditions ( V 0 = 187.1 ± 0.4 Å3) is found to be ~2.5 % larger than for the Al-free phase. We observe an increasing unit-cell anisotropy with increasing pressure, which could have implications for the shear properties of Ca-bearing perovskite in cold slabs subducted into the Earth's mantle.

  5. Elastic and anelastic anomalies in (Ca,Sr)TiO perovskites: Analogue behaviour for silicate perovskites

    OpenAIRE

    Walsh, J.W.; Taylor, P.A.; Buckley, A.; Darling, T.W.; Schreuer, J.; Carpenter, M.A.

    2008-01-01

    Elastic and anelastic anomalies in (Ca,Sr)TiO3 perovskites: Analogue behaviour for silicate perovskites UNITED KINGDOM (Walsh, J.W.) UNITED KINGDOM Received: 2007-10-30 Revised: 2008-02-18 Accepted: 2008-02-27

  6. Research on Removal of Sodium Ferrate to Anionic Synthetic Detergent in Domestic Sewage%高铁酸钠对生活污水中阴离子合成洗涤剂的去除研究

    Institute of Scientific and Technical Information of China (English)

    崔鹏; 王永; 陈文艺

    2015-01-01

    With the removal test research of self-regulating sodium ferrate to anionic synthetic detergent in domestic sewage, by the international standard Methylene Blue Spectrophotometric method, we find out that:Sodium ferrate has a better removal effect on anionic synthetic detergent in domestic sewage, if we add 10ml concentration of sodium ferrate is 1.41 g/L into per 100 ml of domestic sewage, we can make the removal rate of anion synthetic detergent in the samples reach 69.28%.%通过自制的高铁酸钠对生活污水中的阴离子合成洗涤剂进行去除实验研究。采用国标方法亚甲蓝分光光度法进行测定,结果发现:高铁酸钠对生活污水中的阴离子合成洗涤剂有较好的去除作用,每100 mL生活污水中,加入10 mL浓度为1.41 g/L的高铁酸钠,水样中阴离子合成洗涤剂的去除率为69.28%。

  7. 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.

  8. Inorganic perovskite photocatalysts for solar energy utilization.

    Science.gov (United States)

    Zhang, Guan; Liu, Gang; Wang, Lianzhou; Irvine, John T S

    2016-10-24

    The development and utilization of solar energy in environmental remediation and water splitting is being intensively studied worldwide. During the past few decades, tremendous efforts have been devoted to developing non-toxic, low-cost, efficient and stable photocatalysts for water splitting and environmental remediation. To date, several hundreds of photocatalysts mainly based on metal oxides, sulfides and (oxy)nitrides with different structures and compositions have been reported. Among them, perovskite oxides and their derivatives (layered perovskite oxides) comprise a large family of semiconductor photocatalysts because of their structural simplicity and flexibility. This review specifically focuses on the general background of perovskite and its related materials, summarizes the recent development of perovskite photocatalysts and their applications in water splitting and environmental remediation, discusses the theoretical modelling and calculation of perovskite photocatalysts and presents the key challenges and perspectives on the research of perovskite photocatalysts.

  9. Ligand-Stabilized Reduced-Dimensionality Perovskites.

    Science.gov (United States)

    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

    2016-03-02

    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. These drive an increased formation energy and should therefore improve material stability. Here we report 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 achieve 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.

  10. Stability Issues on Perovskite Solar Cells

    OpenAIRE

    2015-01-01

    Organo lead halide perovskite materials like methylammonium lead iodide (CH3NH3PbI3) and formamidinium lead iodide (HC(NH2)2PbI3) 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 natu...

  11. High-performance perovskite light-emitting diodes via morphological control of perovskite films.

    Science.gov (United States)

    Yu, Jae Choul; Kim, Da Bin; Jung, Eui Dae; Lee, Bo Ram; Song, Myoung Hoon

    2016-04-07

    Solution-processable perovskite materials have garnered tremendous attention because of their excellent charge carrier mobility, possibility of a tunable optical bandgap, and high photoluminescence quantum efficiency (PLQE). In particular, the uniform morphology of a perovskite film is the most important factor in realizing perovskite light-emitting diodes (PeLEDs) with high efficiency and full-coverage electroluminescence (EL). In this study, we demonstrate highly efficient PeLEDs that contain a perovskite film with a uniform morphology by introducing HBr into the perovskite precursor. The introduction of HBr into the perovskite precursor results in a perovskite film with a uniform, continuous morphology because the HBr increases the solubility of the inorganic component in the perovskite precursor and reduces the crystallization rate of the perovskite film upon spin-coating. Moreover, PeLEDs fabricated using perovskite films with a uniform, continuous morphology, which were deposited using 6 vol% HBr in a dimethylformamide (DMF)/hydrobromic acid (HBr) cosolvent, exhibited full coverage of the green EL emission. Finally, the optimized PeLEDs fabricated with perovskite films deposited using the DMF/HBr cosolvent exhibited a maximum luminance of 3490 cd m(-2) (at 4.3 V) and a luminous efficiency of 0.43 cd A(-1) (at 4.3 V).

  12. Polarization twist in perovskite ferrielectrics.

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-09-02

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of 'polarization twist', which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  13. Polarization twist in perovskite ferrielectrics

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-01-01

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms. PMID:27586824

  14. Polarization twist in perovskite ferrielectrics

    Science.gov (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-09-01

    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  15. Flexible Hybrid Organic-Inorganic Perovskite Memory.

    Science.gov (United States)

    Gu, Chungwan; Lee, Jang-Sik

    2016-05-24

    Active research has been done on hybrid organic-inorganic perovskite materials for application to solar cells with high power conversion efficiency. However, this material often shows hysteresis, which is undesirable, shift in the current-voltage curve. The hysteresis may come from formation of defects and their movement in perovskite materials. Here, we utilize the defects in perovskite materials to be used in memory operations. We demonstrate flexible nonvolatile memory devices based on hybrid organic-inorganic perovskite as the resistive switching layer on a plastic substrate. A uniform perovskite layer is formed on a transparent electrode-coated plastic substrate by solvent engineering. Flexible nonvolatile memory based on the perovskite layer shows reproducible and reliable memory characteristics in terms of program/erase operations, data retention, and endurance properties. The memory devices also show good mechanical flexibility. It is suggested that resistive switching is done by migration of vacancy defects and formation of conducting filaments under the electric field in the perovskite layer. It is believed that organic-inorganic perovskite materials have great potential to be used in high-performance, flexible memory devices.

  16. Achieving High Performance Perovskite Solar Cells

    Science.gov (United States)

    Yang, Yang

    2015-03-01

    Recently, metal halide perovskite based solar cell with the characteristics of rather low raw materials cost, great potential for simple process and scalable production, and extreme high power conversion efficiency (PCE), have been highlighted as one of the most competitive technologies for next generation thin film photovoltaic (PV). In UCLA, we have realized an efficient pathway to achieve high performance pervoskite solar cells, where the findings are beneficial to this unique materials/devices system. Our recent progress lies in perovskite film formation, defect passivation, transport materials design, interface engineering with respect to high performance solar cell, as well as the exploration of its applications beyond photovoltaics. These achievements include: 1) development of vapor assisted solution process (VASP) and moisture assisted solution process, which produces perovskite film with improved conformity, high crystallinity, reduced recombination rate, and the resulting high performance; 2) examination of the defects property of perovskite materials, and demonstration of a self-induced passivation approach to reduce carrier recombination; 3) interface engineering based on design of the carrier transport materials and the electrodes, in combination with high quality perovskite film, which delivers 15 ~ 20% PCEs; 4) a novel integration of bulk heterojunction to perovskite solar cell to achieve better light harvest; 5) fabrication of inverted solar cell device with high efficiency and flexibility and 6) exploration the application of perovskite materials to photodetector. Further development in film, device architecture, and interfaces will lead to continuous improved perovskite solar cells and other organic-inorganic hybrid optoelectronics.

  17. Photocatalysis: HI-time for perovskites

    Science.gov (United States)

    Vesborg, Peter C. K.

    2017-01-01

    Organolead halide perovskite solar absorbers demonstrate high photovoltaic efficiencies but they are notorious for their intolerance to water. Now, methylammonium lead iodide perovskites are used to harvest solar energy — in water — via photocatalytic generation of hydrogen from solutions of hydriodic acid.

  18. Photocatalysis: HI-time for perovskites

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard

    2017-01-01

    Organolead halide perovskite solar absorbers demonstrate high photovoltaic efficiencies but they are notorious for their intolerance to water. Now, methylammonium lead iodide perovskites are used to harvest solar energy — in water — via photocatalytic generation of hydrogen from solutions of hydr...

  19. Perovskite solar cells: Danger from within

    Science.gov (United States)

    Wilks, Regan G.; Bär, Marcus

    2017-01-01

    Extensive efforts are under way to increase not only the efficiency but also the stability of organic-inorganic halide perovskite based solar cells. However, research shows that iodine-containing perovskites are vulnerable to a self-degradation pathway that may inherently limit their lifetime.

  20. Perovskite Superlattices as Tunable Microwave Devices

    Science.gov (United States)

    Christen, H. M.; Harshavardhan, K. S.

    2003-01-01

    Experiments have shown that superlattices that comprise alternating epitaxial layers of dissimilar paraelectric perovskites can exhibit large changes in permittivity with the application of electric fields. The superlattices are potentially useful as electrically tunable dielectric components of such microwave devices as filters and phase shifters. The present superlattice approach differs fundamentally from the prior use of homogeneous, isotropic mixtures of base materials and dopants. A superlattice can comprise layers of two or more perovskites in any suitable sequence (e.g., ABAB..., ABCDABCD..., ABACABACA...). Even though a single layer of one of the perovskites by itself is not tunable, the compositions and sequence of the layers can be chosen so that (1) the superlattice exhibits low microwave loss and (2) the interfacial interaction between at least two of the perovskites in the superlattice renders either the entire superlattice or else at least one of the perovskites tunable.

  1. 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.

  2. 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.

  3. Understanding the photostability of perovskite solar cell

    Science.gov (United States)

    Joshi, Pranav H.

    Global climate change and increasing energy demands have led to a greater focus on cheaper photovoltaic energy solutions. Perovskite solar cells and organic solar cells have emerged as promising technologies for alternative cheaper photovoltaics. Perovskite solar cells have shown unprecedentedly rapid improvement in power conversion efficiency, from 3% in 2009 to more than 21% today. High absorption coefficient, long diffusion lengths, low exciton binding energy, low defect density and easy of fabrication has made perovskites near ideal material for economical and efficient photovoltaics. However, stability of perovskite and organic solar cells, especially photostability is still not well understood. In this work, we study the photostability of organic solar cells and of perovskite solar cells. (Abstract shortened by ProQuest.).

  4. Organohalide Lead Perovskites for Photovoltaic Applications.

    Science.gov (United States)

    Yusoff, Abd Rashid Bin Mohd; Nazeeruddin, Mohammad Khaja

    2016-03-03

    Perovskite solar cells have recently exhibited a significant leap in efficiency due to their broad absorption, high optical absorption coefficient, very low exciton binding energy, long carrier diffusion lengths, efficient charge collection, and very high open-circuit potential, similar to that of III-IV semiconductors. Unlike silicon solar cells, perovskite solar cells can be developed from a variety of low-temperature solutions processed from inexpensive raw materials. When the perovskite absorber film formation is optimized using solvent engineering, a power conversion efficiency of over 21% has been demonstrated, highlighting the unique photovoltaic properties of perovskite materials. Here, we review the current progress in perovskite solar cells and charge transport materials. We highlight crucial challenges and provide a summary and prospects.

  5. Stability of organometal perovskites with organic overlayers

    Directory of Open Access Journals (Sweden)

    Catherine D. T. Tran

    2015-08-01

    Full Text Available The air-stability of vapour-phase-deposited methylammonium lead triiodide (CH3NH3PbI3 perovskite thin films has been studied using X-ray diffraction. It is found that the perovskite structure without organic coating decomposes completely within a short period of time (∼two days upon exposure to ambient environment. The degradation of the perovskite structure is drastically reduced when the perovskite films are capped with thin N,N′-Di(1-naphthyl-N,N′-diphenyl-(1,1′-biphenyl-4,4′-diamine (NPB films. We discovered that the amount of lead iodide (PbI2, a product of the degradation, grows as a function of time in a sigmoidal manner. Further mathematical modeling analysis shows that the perovskite degradation follows the Avrami equation, a kinetics theory developed for quantifying phase transformations in solid-state materials.

  6. 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.

  7. 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.

  8. Spintronics of Organometal Trihalide Perovskites

    OpenAIRE

    Sun, Dali; Zhang, Chuang; Kavand, Marzieh; van Schooten, Kipp J.; Malissa, Hans; Groesbeck, Matthew; McLaughlin, Ryan; Boehme, Christoph; Vardeny, Z. Valy

    2016-01-01

    The family of organometal trihalide perovskite (OTP), CH3NH3PbX3 (where X is halogen) has recently revolutionized the photovoltaics field and shows promise in a variety of optoelectronic applications. The characteristic spin properties of charge and neutral excitations in OTPs are influenced by the large spin-orbit coupling of the Pb atoms, which may lead to spin-based device applications. Here we report the first studies of pure spin-current and spin-aligned carrier injection in OTP spintron...

  9. Facile preparation of smooth perovskite films for efficient meso/planar hybrid structured perovskite solar cells.

    Science.gov (United States)

    Zhang, Meng; Yu, Hua; Yun, Jung-Ho; Lyu, Miaoqiang; Wang, Qiong; Wang, Lianzhou

    2015-06-21

    Smooth organolead halide perovskite films for meso/planar hybrid structured perovskite solar cells were prepared by a simple compressed air blow-drying method under ambient conditions. The resultant perovskite films show high surface coverage, leading to a device power conversion efficiency of over 10% with an open circuit voltage up to 1.003 V merely using pristine poly(3-hexylthiophene) (P3HT) as a hole transporter.

  10. Degradation efficacy and mechanism of reactive black KBR with ferrate solution%高铁酸盐溶液降解活性黑KBR的效果及机理

    Institute of Scientific and Technical Information of China (English)

    张彦平; 李一兵; 李芬; 李静; 李娟

    2013-01-01

    The degradation efficacy of reactive black KBR with ferrate solution has been studied,and degradation mechanism has been analyzed by UV-Vis and FFIR methods.The experimental results show that ferrate solution has effects of good decolorizing efficacy and fast decolorizing velocity on KBR.When the optimal range of pH ≤ 8,dosage of Fe (Ⅵ) 25 mg/L,and reaction time 60 min,the effects of decolorizing rate and COD removing rate on KBR are 80.3% and 62.5%,respectively.During oxidation degradation process,Fe (Ⅵ) and C1O-in ferrate solution have synergistic effect.The analysis by UV-Vis and FTIR methods shows that during the degradation process,the azo bonds of dye molecules are damaged,benzene ring and heterocyclic of dye molecules are opened,dye macromolecules could be oxidized to small molecule intermediates.%研究了高铁酸盐溶液对活性黑KBR的降解效果,并采用UV-Vis、FTIR对降解机理进行分析.结果表明,高铁酸盐溶液对KBR脱色效果较好,脱色速率较快,最佳pH范围≤8.Fe(Ⅵ)最佳投加量为25 mg/L,反应60 min时,对KBR的色度和COD去除率分别为80.3%、62.5%.在氧化降解过程中,Fe(Ⅵ)和C1O-表现出协同作用.UV-Vis和FTIR分析表明,降解过程中染料分子的偶氮键被破坏,苯环和杂环被打开,染料大分子被氧化为小分子中间产物.

  11. Strongly correlated perovskite fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D.; Ramanathan, Shriram

    2016-05-16

    Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines1, 2, 3, 4. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number5. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes6. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.

  12. Strongly correlated perovskite fuel cells

    Science.gov (United States)

    Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D.; Ramanathan, Shriram

    2016-06-01

    Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.

  13. Experimental studies of magnetic perovskites

    Science.gov (United States)

    Golovanov, Vladimir Valentinovich

    1998-11-01

    The present work addresses the phenomenon of Giant Magnetoresistance (GMR) and the role of Jahn-Teller distortion in the conduction mechanism of GMR materials. For this purpose, GMR and related perovskites are studied experimentally using infrared reflection spectroscopy, synchrotron x-ray diffraction, and electrical transport measurements. Reflectivity and x-ray diffraction studies of a vacancy doped rhombohedrally distorted GMR material, La0.936Mn0.982O3, indicate the presence of dynamic Jahn-Teller distortion above the magnetic ordering temperature (Tc = 225K) and a substantial reduction of the distortion below Tc. In particular, above Tc, the optical conductivity of large single crystals of the material shows the broad peak around 10,000 cm-1, which shifts towards zero frequency as the ferromagnetic state develops. The peak is attributed to the Jahn-Teller splitting of the two-fold degenerate eg level. Powder x-ray diffraction measurements performed on the same material reveal a sharp 3% reduction of the rhombohedral distortion at the magnetic ordering temperature. This reduction reflects the decrease in the magnitude of the dynamic Jahn-Teller distortion at the magnetic ordering. The transport and magnetic measurements on non Jahn-Teller active La1-xSrxCoO3 perovskites show much lower magnetoresistance, compatible with the conventional double-exchange theory. The relatively high values of magnetoresistance for low doped (x ≤ 0.15) compounds at low temperatures are also interpreted in terms of the double-exchange model.

  14. Strongly correlated perovskite fuel cells.

    Science.gov (United States)

    Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D; Ramanathan, Shriram

    2016-06-09

    Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.

  15. 二沉池出水中双酚A的高铁酸钾氧化降解行为%Potassium ferrate (Ⅵ) degradation of bisphenol A in the secondary sedimentation tank effluent

    Institute of Scientific and Technical Information of China (English)

    丁博; 尹平河; 赵玲; 王丹

    2011-01-01

    考察了pH、温度、反应时间、浓度、光照、腐殖酸、干扰离子等因素对高铁酸钾降解双酚A的影响,并探讨了高铁酸钾降解双酚A的动力学机理以及对二沉池出水中双酚A的降解作用.研究表明:在pH=9.0,室温条件下,反应10min后双酚A的降解率达最大值;光照对双酚A降解基本没有影响;腐殖酸对双酚A的降解有一定促进作用;干扰离子对双酚A降解影响较为复杂,既有促进作用又有抑制作用.以二沉池出水为基体,当m(高铁酸钾):m(双酚A)=5:1,双酚A初始质量浓度为5.0 mg/L时,反应4min后,双酚A的降解率达99%.实验结果表明高铁酸钾对双酚A具有良好的降解效果.%The effects of pH, te mperature,time, concentration, illumination, humic acid, interference ions, etc. on potassium ferrate ( Ⅵ ) degradation of bisphenol A have been investigated. The kinetics mechanisms of potassium ferrate (Ⅵ) degradation of bisphenol A and the degradation effect on the secondary sedimentation tank effluent are discussed. The research shows that the degradation rate of bisphenol A reaches the maximum value ,when pH is 9.0,at room temperature and reaction time is 10 min. Illumination has no effect on the degradation of bisphenol A, humic acid has stimulative effect on the degradation of bisphenol A to a certain extent, and the effect of interference ions on the degradation of bisphenol A is rather complicated, having both stimulative effect and inhibition effect. The secondary sedimentation tank effluent is used as substrate, and the degradation rate of bisphenol A reaches 99%,when m[potassium ferrate ( Ⅵ )] :m(bisphenol A)=5:l ,the initial mass concentration of bisphenol A is 5.0 mg/L and reaction time is 4 min. The results show that potassium ferrate (Ⅵ) has quite good degradation effect on bisphenol A.

  16. Semitransparent Fully Air Processed Perovskite Solar Cells.

    Science.gov (United States)

    Bu, Lingling; Liu, Zonghao; Zhang, Meng; Li, Wenhui; Zhu, Aili; Cai, Fensha; Zhao, Zhixin; Zhou, Yinhua

    2015-08-19

    Semitransparent solar cells are highly attractive for application as power-generating windows. In this work, we present semitransparent perovskite solar cells that employ conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) film as the transparent counter electrode. The PSS electrode is prepared by transfer lamination technique using plastic wrap as the transfer medium. The use of the transfer lamination technique avoids the damage of the CH3NH3PbI3 perovskite film by direct contact of PSS aqueous solution. The semitransparent perovskite solar cells yield a power conversion efficiency of 10.1% at an area of about 0.06 cm(2) and 2.9% at an area of 1 cm(2). The device structure and the fabrication technique provide a facile way to produce semitransparent perovskite solar cells.

  17. 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.

  18. Perovskite thin films via atomic layer deposition.

    Science.gov (United States)

    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

    2015-01-01

    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 CH3 NH3 PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm(-1) .

  19. Perovskite Solar Cells: Beyond Methylammonium Lead Iodide.

    Science.gov (United States)

    Boix, Pablo P; Agarwala, Shweta; Koh, Teck Ming; Mathews, Nripan; Mhaisalkar, Subodh G

    2015-03-05

    Organic-inorganic lead halide based perovskites solar cells are by far the highest efficiency solution-processed solar cells, threatening to challenge thin film and polycrystalline silicon ones. Despite the intense research in this area, concerns surrounding the long-term stability as well as the toxicity of lead in the archetypal perovskite, CH3NH3PbI3, have the potential to derail commercialization. Although the search for Pb-free perovskites have naturally shifted to other transition metal cations and formulations that replace the organic moiety, efficiencies with these substitutions are still substantially lower than those of the Pb-perovskite. The perovskite family offers rich multitudes of crystal structures and substituents with the potential to uncover new and exciting photophysical phenomena that hold the promise of higher solar cell efficiencies. In addressing materials beyond CH3NH3PbI3, this Perspective will discuss a broad palette of elemental substitutions, solid solutions, and multidimensional families that will provide the next fillip toward market viability of the perovskite solar cells.

  20. Modeling hybrid perovskites by molecular dynamics.

    Science.gov (United States)

    Mattoni, Alessandro; Filippetti, Alessio; Caddeo, Claudia

    2017-02-01

    The topical review describes the recent progress in the modeling of hybrid perovskites by molecular dynamics simulations. Hybrid perovskites and in particular methylammonium lead halide (MAPI) have a tremendous technological relevance representing the fastest-advancing solar material to date. They also represent the paradigm of an organic-inorganic crystalline material with some conceptual peculiarities: an inorganic semiconductor for what concerns the electronic and absorption properties with a hybrid and solution processable organic-inorganic body. After briefly explaining the basic concepts of ab initio and classical molecular dynamics, the model potential recently developed for hybrid perovskites is described together with its physical motivation as a simple ionic model able to reproduce the main dynamical properties of the material. Advantages and limits of the two strategies (either ab initio or classical) are discussed in comparison with the time and length scales (from pico to microsecond scale) necessary to comprehensively study the relevant properties of hybrid perovskites from molecular reorientations to electrocaloric effects. The state-of-the-art of the molecular dynamics modeling of hybrid perovskites is reviewed by focusing on a selection of showcase applications of methylammonium lead halide: molecular cations disorder; temperature evolution of vibrations; thermally activated defects diffusion; thermal transport. We finally discuss the perspectives in the modeling of hybrid perovskites by molecular dynamics.

  1. 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.

  2. Perovskite solar cells: from materials to devices.

    Science.gov (United States)

    Jung, Hyun Suk; Park, Nam-Gyu

    2015-01-07

    Perovskite solar cells based on organometal halide light absorbers have been considered a promising photovoltaic technology due to their superb power conversion efficiency (PCE) along with very low material costs. Since the first report on a long-term durable solid-state perovskite solar cell with a PCE of 9.7% in 2012, a PCE as high as 19.3% was demonstrated in 2014, and a certified PCE of 17.9% was shown in 2014. Such a high photovoltaic performance is attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths. Nevertheless, there are lots of puzzles to unravel the basis for such high photovoltaic performances. The working principle of perovskite solar cells has not been well established by far, which is the most important thing for understanding perovksite solar cells. In this review, basic fundamentals of perovskite materials including opto-electronic and dielectric properties are described to give a better understanding and insight into high-performing perovskite solar cells. In addition, various fabrication techniques and device structures are described toward the further improvement of perovskite solar cells.

  3. Modeling hybrid perovskites by molecular dynamics

    Science.gov (United States)

    Mattoni, Alessandro; Filippetti, Alessio; Caddeo, Claudia

    2017-02-01

    The topical review describes the recent progress in the modeling of hybrid perovskites by molecular dynamics simulations. Hybrid perovskites and in particular methylammonium lead halide (MAPI) have a tremendous technological relevance representing the fastest-advancing solar material to date. They also represent the paradigm of an organic-inorganic crystalline material with some conceptual peculiarities: an inorganic semiconductor for what concerns the electronic and absorption properties with a hybrid and solution processable organic-inorganic body. After briefly explaining the basic concepts of ab initio and classical molecular dynamics, the model potential recently developed for hybrid perovskites is described together with its physical motivation as a simple ionic model able to reproduce the main dynamical properties of the material. Advantages and limits of the two strategies (either ab initio or classical) are discussed in comparison with the time and length scales (from pico to microsecond scale) necessary to comprehensively study the relevant properties of hybrid perovskites from molecular reorientations to electrocaloric effects. The state-of-the-art of the molecular dynamics modeling of hybrid perovskites is reviewed by focusing on a selection of showcase applications of methylammonium lead halide: molecular cations disorder; temperature evolution of vibrations; thermally activated defects diffusion; thermal transport. We finally discuss the perspectives in the modeling of hybrid perovskites by molecular dynamics.

  4. Modeling Anomalous Hysteresis in Perovskite Solar Cells.

    Science.gov (United States)

    van Reenen, Stephan; Kemerink, Martijn; Snaith, Henry J

    2015-10-01

    Organic-inorganic lead halide perovskites are distinct from most other semiconductors because they exhibit characteristics of both electronic and ionic motion. Accurate understanding of the optoelectronic impact of such properties is important to fully optimize devices and be aware of any limitations of perovskite solar cells and broader optoelectronic devices. Here we use a numerical drift-diffusion model to describe device operation of perovskite solar cells. To achieve hysteresis in the modeled current-voltage characteristics, we must include both ion migration and electronic charge traps, serving as recombination centers. Trapped electronic charges recombine with oppositely charged free electronic carriers, of which the density depends on the bias-dependent ion distribution in the perovskite. Our results therefore show that reduction of either the density of mobile ionic species or carrier trapping at the perovskite interface will remove the adverse hysteresis in perovskite solar cells. This gives a clear target for ongoing research effort and unifies previously conflicting experimental observations and theories.

  5. Molecular dynamics simulations of organohalide perovskite precursors: solvent effects in the formation of perovskite solar cells.

    Science.gov (United States)

    Gutierrez-Sevillano, Juan José; Ahmad, Shahzada; Calero, Sofía; Anta, Juan A

    2015-09-21

    The stability and desirable crystal formation of organohalide perovskite semiconductors is of utmost relevance to ensure the success of perovskites in photovoltaic technology. Herein we have simulated the dynamics of ionic precursors toward the formation of embryonic organohalide perovskite CH3NH3PbI3 units in the presence of solvent molecules using Molecular Dynamics. The calculations involved, a variable amount of Pb(2+), I(-), and CH3NH3(+) ionic precursors in water, pentane and a mixture of these two solvents. Suitable force fields for solvents and precursors have been tested and used to carry out the simulations. Radial distribution functions and mean square displacements confirm the formation of basic perovskite crystalline units in pure pentane - taken as a simple and archetypal organic solvent. In contrast, simulations in water confirm the stability of the solvated ionic precursors, which prevents their aggregation to form the perovskite compound. We have found that in the case of a water/pentane binary solvent, a relatively small amount of water did not hinder the perovskite formation. Thus, our findings suggest that the cause of the poor stability of perovskite films in the presence of moisture is a chemical reaction, rather than the polar nature of the solvents. Based on the results, a set of force-field parameters to study from first principles perovskite formation and stability, also in the solid phase, is proposed.

  6. Hybrid Perovskite Light-Emitting Diodes Based on Perovskite Nanocrystals with Organic-Inorganic Mixed Cations.

    Science.gov (United States)

    Zhang, Xiaoli; Liu, He; Wang, Weigao; Zhang, Jinbao; Xu, Bing; Karen, Ke Lin; Zheng, Yuanjin; Liu, Sheng; Chen, Shuming; Wang, Kai; Sun, Xiao Wei

    2017-03-07

    Organic-inorganic hybrid perovskite materials with mixed cations have demonstrated tremendous advances in photovoltaics recently, by showing a significant enhancement of power conversion efficiency and improved perovskite stability. Inspired by this development, this study presents the facile synthesis of mixed-cation perovskite nanocrystals based on FA(1-x) Csx PbBr3 (FA = CH(NH2 )2 ). By detailed characterization of their morphological, optical, and physicochemical properties, it is found that the emission property of the perovskite, FA(1-x) Csx PbBr3 , is significantly dependent on the substitution content of the Cs cations in the perovskite composition. These mixed-cation perovskites are employed as light emitters in light-emitting diodes (LEDs). With an optimized composition of FA0.8 Cs0.2 PbBr3 , the LEDs exhibit encouraging performance with a highest reported luminance of 55 005 cd m(-2) and a current efficiency of 10.09 cd A(-1) . This work provides important instructions on the future compositional optimization of mixed-cation perovskite for obtaining high-performance LEDs. The authors believe this work is a new milestone in the development of bright and efficient perovskite LEDs.

  7. Strategic improvement of the long-term stability of perovskite materials and perovskite solar cells.

    Science.gov (United States)

    Xu, Tingting; Chen, Lixin; Guo, Zhanhu; Ma, Tingli

    2016-10-05

    Perovskite solar cells (PSCs) have gained tremendous research interest in recent several years. To date the power conversion efficiency (PCE) of PSCs has been increased from 3.8% to over 22.1%, showing that they have a promising future as a renewable energy resource to compete with conventional silicon solar cells. However, a crucial challenge of PSCs currently is that perovskite materials and PSCs have limitations of easy degradation and inferior long-term stabilities, thus hampering their future commercial applications. In this review, the degradation mechanisms for instable perovskite materials and their corresponding solar cells are discussed. The stability study of perovskite materials and PSCs from the aspect of experimental tests and theoretical calculations is reviewed. The strategies for enhancing the stability of perovskite materials and PSCs are summarized from the viewpoints of perovskite material engineering, substituted organic and inorganic materials for hole transportation, alternative electrodes comprising mainly carbon and its relevant composites, interfacial modification, novel device structure construction and encapsulation, etc. Various approaches and outlooks on the future direction of perovskite materials and PSCs are highlighted. This review is expected to provide helpful insights for further enhancing the stability of perovskite materials and PSCs in this exciting field.

  8. Multiferroicity in Perovskite Manganite Superlattice

    Science.gov (United States)

    Tao, Yong-Mei; Jiang, Xue-Fan; Liu, Jun-Ming

    2016-08-01

    Multiferroic properties of short period perovskite type manganite superlattice ((R1MnO3)n/(R2MnO3)n (n=1,2,3)) are considered within the framework of classical Heisenberg model using Monte Carlo simulation. Our result revealed the interesting behaviors in Mn spins structure in superlattice. Apart from simple plane spin cycloid structure which is shown in all manganites including bulk, film, and superlattice here in low temperature, a non-coplanar spiral spin structure is exhibited in a certain temperature range when n equals 1, 2 or 3. Specific heat, spin-helicity vector, spin correlation function, spin-helicity correlation function, and spin configuration are calculated to confirm this non-coplanar spiral spin structure. These results are associated with the competition among exchange interaction, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. Supported by the National Natural Science Foundation of China (NSFC) under Grant No. 11447136

  9. Electrochemical Doping of Halide Perovskites with Ion Intercalation.

    Science.gov (United States)

    Jiang, Qinglong; Chen, Mingming; Li, Junqiang; Wang, Mingchao; Zeng, Xiaoqiao; Besara, Tiglet; Lu, Jun; Xin, Yan; Shan, Xin; Pan, Bicai; Wang, Changchun; Lin, Shangchao; Siegrist, Theo; Xiao, Qiangfeng; Yu, Zhibin

    2017-01-24

    Halide perovskites have recently been investigated for various solution-processed optoelectronic devices. The majority of studies have focused on using intrinsic halide perovskites, and the intentional incoporation of dopants has not been well explored. In this work, we discovered that small alkali ions, including lithium and sodium ions, could be electrochemically intercalated into a variety of halide and pseudohalide perovskites. The ion intercalation caused a lattice expansion of the perovskite crystals and resulted in an n-type doping of the perovskites. Such electrochemical doping improved the conductivity and changed the color of the perovskites, leading to an electrochromism with more than 40% reduction of transmittance in the 450-850 nm wavelength range. The doped perovskites exhibited improved electron injection efficiency into the pristine perovskite crystals, resulting in bright light-emitting diodes with a low turn-on voltage.

  10. 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-C60 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.

  11. Neutral- and Multi-Colored Semitransparent Perovskite Solar Cells

    OpenAIRE

    Kyu-Tae Lee; L. Jay Guo; Hui Joon Park

    2016-01-01

    In this review, we summarize recent works on perovskite solar cells with neutral- and multi-colored semitransparency for building-integrated photovoltaics and tandem solar cells. The perovskite solar cells exploiting microstructured arrays of perovskite “islands” and transparent electrodes—the latter of which include thin metallic films, metal nanowires, carbon nanotubes, graphenes, and transparent conductive oxides for achieving optical transparency—are investigated. Moreover, the perovskite...

  12. Making and Breaking of Lead Halide Perovskites

    KAUST Repository

    Manser, Joseph S.

    2016-02-16

    A new front-runner has emerged in the field of next-generation photovoltaics. A unique class of materials, known as organic metal halide perovskites, bridges the gap between low-cost fabrication and exceptional device performance. These compounds can be processed at low temperature (typically in the range 80–150 °C) and readily self-assemble from the solution phase into high-quality semiconductor thin films. The low energetic barrier for crystal formation has mixed consequences. On one hand, it enables inexpensive processing and both optical and electronic tunability. The caveat, however, is that many as-formed lead halide perovskite thin films lack chemical and structural stability, undergoing rapid degradation in the presence of moisture or heat. To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice of solvent treatment. Proper characterization and tuning of processing parameters can aid in rational optimization of perovskite devices. Likewise, gaining a comprehensive understanding of the degradation mechanism and identifying components of the perovskite structure that may be particularly susceptible to attack by moisture are vital to mitigate device degradation under operating conditions. This Account provides insight into the lifecycle of organic–inorganic lead halide perovskites, including (i) the nature of the precursor solution, (ii) formation of solid-state perovskite thin films and single crystals, and (iii) transformation of perovskites into hydrated phases upon exposure to moisture. In particular, spectroscopic and structural characterization techniques shed light on the thermally driven evolution of the perovskite structure. By tuning precursor stoichiometry and chemistry, and thus the lead halide charge-transfer complexes present in solution, crystallization

  13. Making and Breaking of Lead Halide Perovskites.

    Science.gov (United States)

    Manser, Joseph S; Saidaminov, Makhsud I; Christians, Jeffrey A; Bakr, Osman M; Kamat, Prashant V

    2016-02-16

    A new front-runner has emerged in the field of next-generation photovoltaics. A unique class of materials, known as organic metal halide perovskites, bridges the gap between low-cost fabrication and exceptional device performance. These compounds can be processed at low temperature (typically in the range 80-150 °C) and readily self-assemble from the solution phase into high-quality semiconductor thin films. The low energetic barrier for crystal formation has mixed consequences. On one hand, it enables inexpensive processing and both optical and electronic tunability. The caveat, however, is that many as-formed lead halide perovskite thin films lack chemical and structural stability, undergoing rapid degradation in the presence of moisture or heat. To date, improvements in perovskite solar cell efficiency have resulted primarily from better control over thin film morphology, manipulation of the stoichiometry and chemistry of lead halide and alkylammonium halide precursors, and the choice of solvent treatment. Proper characterization and tuning of processing parameters can aid in rational optimization of perovskite devices. Likewise, gaining a comprehensive understanding of the degradation mechanism and identifying components of the perovskite structure that may be particularly susceptible to attack by moisture are vital to mitigate device degradation under operating conditions. This Account provides insight into the lifecycle of organic-inorganic lead halide perovskites, including (i) the nature of the precursor solution, (ii) formation of solid-state perovskite thin films and single crystals, and (iii) transformation of perovskites into hydrated phases upon exposure to moisture. In particular, spectroscopic and structural characterization techniques shed light on the thermally driven evolution of the perovskite structure. By tuning precursor stoichiometry and chemistry, and thus the lead halide charge-transfer complexes present in solution, crystallization

  14. Oxidative transformation of micropollutants during municipal wastewater treatment: comparison of kinetic aspects of selective (chlorine, chlorine dioxide, ferrate VI, and ozone) and non-selective oxidants (hydroxyl radical).

    Science.gov (United States)

    Lee, Yunho; von Gunten, Urs

    2010-01-01

    Chemical oxidation processes have been widely applied to water treatment and may serve as a tool to minimize the release of micropollutants (e.g. pharmaceuticals and endocrine disruptors) from municipal wastewater effluents into the aquatic environment. The potential of several oxidants for the transformation of selected micropollutants such as atenolol, carbamazepine, 17 alpha-ethinylestradiol (EE2), ibuprofen, and sulfamethoxazole was assessed and compared. The oxidants include chlorine, chlorine dioxide, ferrate(VI), and ozone as selective oxidants versus hydroxyl radicals as non-selective oxidant. Second-order rate constants (k) for the reaction of each oxidant show that the selective oxidants react only with some electron-rich organic moieties (ERMs), such as phenols, anilines, olefins, and deprotonated-amines. In contrast, hydroxyl radicals show a nearly diffusion-controlled reactivity with almost all organic moieties (k>or=10(9)M(-1) s(-1)). Due to a competition for oxidants between a target micropollutant and wastewater matrix (i.e. effluent organic matter, EfOM), a higher reaction rate with a target micropollutant does not necessarily translate into more efficient transformation. For example, transformation efficiencies of EE2, a phenolic micropollutant, in a selected wastewater effluent at pH 8 varied only within a factor of 7 among the selective oxidants, even though the corresponding k for the reaction of each selective oxidant with EE2 varied over four orders of magnitude. In addition, for the selective oxidants, the competition disappears rapidly after the ERMs present in EfOM are consumed. In contrast, for hydroxyl radicals, the competition remains practically the same during the entire oxidation. Therefore, for a given oxidant dose, the selective oxidants were more efficient than hydroxyl radicals for transforming ERMs-containing micropollutants, while hydroxyl radicals are capable of transforming micropollutants even without ERMs. Besides Ef

  15. Patterning of perovskite-polymer films by wrinkling instabilities.

    Science.gov (United States)

    Nasti, G; Sanchez, S; Gunkel, I; Balog, S; Roose, B; Wilts, B D; Teuscher, J; Gentile, G; Cerruti, P; Ambrogi, V; Carfagna, C; Steiner, U; Abate, A

    2017-02-22

    Organic-inorganic perovskites are semiconductors used for applications in optoelectronics and photovoltaics. Micron and submicron perovskite patterns have been explored in semitransparent photovoltaic and lasing applications. In this work, we show that a polymeric medium can be used to create a patterned perovskite, by using a novel and inexpensive approach.

  16. X-ray imaging: Perovskites target X-ray detection

    Science.gov (United States)

    Heiss, Wolfgang; Brabec, Christoph

    2016-05-01

    Single crystals of perovskites are currently of interest to help fathom fundamental physical parameters limiting the performance of perovskite-based polycrystalline solar cells. Now, such perovskites offer a technology platform for optoelectronic devices, such as cheap and sensitive X-ray detectors.

  17. Electrochemical studies of perovskite mixed conductors

    Energy Technology Data Exchange (ETDEWEB)

    Brosha, E.L.; Chung, B.W.; Garzon, F.H. [Los Alamos National Lab., NM (United States). Electronic and Electrochemical Materials and Devices Group

    1994-12-01

    Research into the growth of high-quality single crystal thin films of high transition temperature {Tc} superconductors have stimulated interest in other perovskite metal oxides with a variety of physical properties. Thin films of perovskite materials are among the major focal research areas for optical, sensor, electronic, and superconducting applications. Two lanthanum-based oxygen/electronic conducting perovskite oxides of particular interest for high temperature fuel cell electrodes and interconnects and for other electrochemical applications such as oxygen separation devices are La{sub 1{minus}x}Sr{sub x}MnO{sub 3{minus}y} and La{sub 1{minus}x}Sr{sub x}CoO{sub 3{minus}y}. The La-based perovskites are valuable for these technologies because they reduce interfacial resistances by eliminating the need for a three phase contact area (gas, metal electrode, electrolyte). In addition, these oxides may also serve a valuable role as novel catalysts or catalytic supports; however, little is known about what catalytic properties they may possess. Fundamental study of the electrochemical, diffusional oxygen transport, and surface catalytic properties of these materials can be greatly simplified if the complications associated with the presence of grain boundaries and multiple crystallite orientations can be avoided. Therefore, single crystals of these La-based perovskites become highly desirable. In this work, the authors report the structural and electrical properties of highly oriented thin films of La{sub 0.84}Sr{sub 0.16}MnO{sub 3} and La{sub 0.8}Sr{sub 0.2}CoO{sub 3} grown on single crystal Y-ZrO{sub 2} substrates. An addition, the authors have demonstrated growing, in situ, epitaxial multilayer perovskite/fluorite/perovskite configurations for fundamental fuel cell modeling.

  18. Bismuth centred magnetic perovskite: A projected multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Asish K., E-mail: asish.k@gmail.com [Discipline of Physics, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India); Seikh, Md. Motin [Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal 731235 (India); Nautiyal, Pranjal [Discipline of Mechanical Engineering, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India)

    2015-03-15

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO{sub 3} and BiFeO{sub 3} are the well-studied Bi-centred multiferroic oxides. BiMnO{sub 3} is a ferromagnetic–ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO{sub 3} phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La{sub 0.5}Bi{sub 0.5}MnO{sub 3} perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La{sub 0.5}Bi{sub 0.5}Mn{sub 0.67}Co{sub 0.33}O{sub 3} with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s{sup 2} lone pair of Bi{sup 3+} cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material. - Highlights: • Multiferroics have attracted increasing attention due to their possible device applications. • Bismuth centred magnetic perovskite is one kind of such promising multiferroic materials. • Ferromagnetic Bi-perovskites, which are synthesized at ambient conditions, have been discussed.

  19. 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

  20. Nanoimprinted Perovskite Nanograting Photodetector with Improved Efficiency.

    Science.gov (United States)

    Wang, Honglei; Haroldson, Ross; Balachandran, Balasubramaniam; Zakhidov, Alex; Sohal, Sandeep; Chan, Julia Y; Zakhidov, Anvar; Hu, Walter

    2016-12-27

    Recently, organolead halide-based perovskites have emerged as promising materials for optoelectronic applications, particularly for photovoltaics, photodetectors, and lasing, with low cost and high performance. Meanwhile, nanoscale photodetectors have attracted tremendous attention toward realizing miniaturized optoelectronic systems, as they offer high sensitivity, ultrafast response, and the capability to detect beyond the diffraction limit. Here we report high-performance nanoscale-patterned perovskite photodetectors implemented by nanoimprint lithography (NIL). The spin-coated lead methylammonium triiodide perovskite shows improved crystallinity and optical properties after NIL. The nanoimprinted metal-semiconductor-metal photodetectors demonstrate significantly improved performance compared to the nonimprinted conventional thin-film devices. The effects of NIL pattern geometries on the optoelectronic characteristics were studied, and the nanograting pattern based photodetectors demonstrated the best performance, showing approximately 35 times improvement on responsivity and 7 times improvement on on/off ratio compared with the nonimprinted devices. The high performance of NIL-nanograting photodetectors likely results from high crystallinity and favored nanostructure morphology, which contribute to higher mobility, longer diffusion length, and better photon absorption. Our results have demonstrated that the NIL is a cost-effective method to fabricate high-performance perovskite nanoscale optoelectronic devices, which may be suitable for manufacturing of high-density perovskite nanophotodetector arrays and to provide integration with state-of-the-art electronic circuits.

  1. Quantum-dot-in-perovskite solids

    KAUST Repository

    Ning, Zhijun

    2015-07-15

    © 2015 Macmillan Publishers Limited. All rights reserved. Heteroepitaxy - atomically aligned growth of a crystalline film atop a different crystalline substrate - is the basis of electrically driven lasers, multijunction solar cells, and blue-light-emitting diodes. Crystalline coherence is preserved even when atomic identity is modulated, a fact that is the critical enabler of quantum wells, wires, and dots. The interfacial quality achieved as a result of heteroepitaxial growth allows new combinations of materials with complementary properties, which enables the design and realization of functionalities that are not available in the single-phase constituents. Here we show that organohalide perovskites and preformed colloidal quantum dots, combined in the solution phase, produce epitaxially aligned \\'dots-in-a-matrix\\' crystals. Using transmission electron microscopy and electron diffraction, we reveal heterocrystals as large as about 60 nanometres and containing at least 20 mutually aligned dots that inherit the crystalline orientation of the perovskite matrix. The heterocrystals exhibit remarkable optoelectronic properties that are traceable to their atom-scale crystalline coherence: photoelectrons and holes generated in the larger-bandgap perovskites are transferred with 80% efficiency to become excitons in the quantum dot nanocrystals, which exploit the excellent photocarrier diffusion of perovskites to produce bright-light emission from infrared-bandgap quantum-tuned materials. By combining the electrical transport properties of the perovskite matrix with the high radiative efficiency of the quantum dots, we engineer a new platform to advance solution-processed infrared optoelectronics.

  2. Epitaxial Halide Perovskite Lateral Double Heterostructure.

    Science.gov (United States)

    Wang, Yiping; Chen, Zhizhong; Deschler, Felix; Sun, Xin; Lu, Toh-Ming; Wertz, Esther A; Hu, Jia-Mian; Shi, Jian

    2017-03-28

    Epitaxial III-V semiconductor heterostructures are key components in modern microelectronics, electro-optics, and optoelectronics. With superior semiconducting properties, halide perovskite materials are rising as promising candidates for coherent heterostructure devices. In this report, spinodal decomposition is proposed and experimentally implemented to produce epitaxial double heterostructures in halide perovskite system. Pristine epitaxial mixed halide perovskites rods and films were synthesized via van der Waals epitaxy by chemical vapor deposition method. At room temperature, photon was applied as a knob to regulate the kinetics of spinodal decomposition and classic coarsening. By this approach, halide perovskite double heterostructures were created carrying epitaxial interfaces and outstanding optical properties. Reduced Fröhlich electron-phonon coupling was discovered in coherent halide double heterostructure, which is hypothetically attributed to the classic phonon confinement effect widely existing in III-V double heterostructures. As a proof-of-concept, our results suggest that halide perovskite-based epitaxial heterostructures may be promising for high-performance and low-cost optoelectronics, electro-optics, and microelectronics. Thus, ultimately, for practical device applications, it may be worthy to pursue these heterostructures via conventional vapor phase epitaxy approaches widely practised in III-V field.

  3. Trap states in lead iodide perovskites.

    Science.gov (United States)

    Wu, Xiaoxi; Trinh, M Tuan; Niesner, Daniel; Zhu, Haiming; Norman, Zachariah; Owen, Jonathan S; Yaffe, Omer; Kudisch, Bryan J; Zhu, X-Y

    2015-02-11

    Recent discoveries of highly efficient solar cells based on lead iodide perovskites have led to a surge in research activity on understanding photo carrier generation in these materials, but little is known about trap states that may be detrimental to solar cell performance. Here we provide direct evidence for hole traps on the surfaces of three-dimensional (3D) CH3NH3PbI3 perovskite thin films and excitonic traps below the optical gaps in these materials. The excitonic traps possess weak optical transition strengths, can be populated from the relaxation of above gap excitations, and become more significant as dimensionality decreases from 3D CH3NH3PbI3 to two-dimensional (2D) (C4H9NH3I)2(CH3NH3I)(n-1)(PbI2)(n) (n = 1, 2, 3) perovskites and, within the 2D family, as n decreases from 3 to 1. We also show that the density of excitonic traps in CH3NH3PbI3 perovskite thin films grown in the presence of chloride is at least one-order of magnitude lower than that grown in the absence of chloride, thus explaining a widely known mystery on the much better solar cell performance of the former. The trap states are likely caused by electron-phonon coupling and are enhanced at surfaces/interfaces where the perovskite crystal structure is most susceptible to deformation.

  4. Perovskites with the Framework-Forming Xenon.

    Science.gov (United States)

    Britvin, Sergey N; Kashtanov, Sergei A; Krzhizhanovskaya, Maria G; Gurinov, Andrey A; Glumov, Oleg V; Strekopytov, Stanislav; Kretser, Yury L; Zaitsev, Anatoly N; Chukanov, Nikita V; Krivovichev, Sergey V

    2015-11-23

    The Group 18 elements (noble gases) were the last ones in the periodic system to have not been encountered in perovskite structures. We herein report the synthesis of a new group of double perovskites KM(XeNaO6) (M = Ca, Sr, Ba) containing framework-forming xenon. The structures of the new compounds, like other double perovskites, are built up of the alternating sequence of corner-sharing (XeO6) and (NaO6) octahedra arranged in a three-dimensional rocksalt order. The fact that xenon can be incorporated into the perovskite structure provides new insights into the problem of Xe depletion in the atmosphere. Since octahedrally coordinated Xe(VIII) and Si(IV) exhibit close values of ionic radii (0.48 and 0.40 Å, respectively), one could assume that Xe(VIII) can be incorporated into hyperbaric frameworks such as MgSiO3 perovskite. The ability of Xe to form stable inorganic frameworks can further extend the rich and still enigmatic chemistry of this noble gas.

  5. Bismuth centred magnetic perovskite: A projected multiferroic

    Science.gov (United States)

    Kundu, Asish K.; Seikh, Md. Motin; Nautiyal, Pranjal

    2015-03-01

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO3 and BiFeO3 are the well-studied Bi-centred multiferroic oxides. BiMnO3 is a ferromagnetic-ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO3 phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La0.5Bi0.5MnO3 perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La0.5Bi0.5Mn0.67Co0.33O3 with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s2 lone pair of Bi3+ cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material.

  6. Dissolution-recrystallization method for high efficiency perovskite solar cells

    Science.gov (United States)

    Han, Fei; Luo, Junsheng; Wan, Zhongquan; Liu, Xingzhao; Jia, Chunyang

    2017-06-01

    In this work, a dissolution-recrystallization method (DRM) with chlorobenzene and dimethylsulfoxide treating the perovskite films during the spin-coating process is reported. This is the first time that DRM is used to control perovskite crystallization and improve the device performance. Furthermore, the DRM is good for reducing defects and grain boundaries, improving perovskite crystallization and even improving TiO2/perovskite interface. By optimizing, the DRM2-treated perovskite solar cell (PSC) obtains the best photoelectric conversion efficiency (PCE) of 16.76% under AM 1.5 G illumination (100 mW cm-2) with enhanced Jsc and Voc compared to CB-treated PSC.

  7. Autothermal reforming catalyst having perovskite structure

    Science.gov (United States)

    Krumpel, Michael; Liu, Di-Jia

    2009-03-24

    The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

  8. Metal halide perovskites for energy applications

    Science.gov (United States)

    Zhang, Wei; Eperon, Giles E.; Snaith, Henry J.

    2016-06-01

    Exploring prospective materials for energy production and storage is one of the biggest challenges of this century. Solar energy is one of the most important renewable energy resources, due to its wide availability and low environmental impact. Metal halide perovskites have emerged as a class of semiconductor materials with unique properties, including tunable bandgap, high absorption coefficient, broad absorption spectrum, high charge carrier mobility and long charge diffusion lengths, which enable a broad range of photovoltaic and optoelectronic applications. Since the first embodiment of perovskite solar cells showing a power conversion efficiency of 3.8%, the device performance has been boosted up to a certified 22.1% within a few years. In this Perspective, we discuss differing forms of perovskite materials produced via various deposition procedures. We focus on their energy-related applications and discuss current challenges and possible solutions, with the aim of stimulating potential new applications.

  9. Organometallic perovskites for optoelectronic applications (Conference Presentation)

    Science.gov (United States)

    Levchuk, Levgen; Hoegl, Florian; Brandl, Marco; Osvet, Andres; Hock, Rainer; Herre, Patrick; Wolfgang, Wolfgang; Schweizer, Peter; Spiecker, Erdmann; Batentschuk, Miroslaw; Brabec, Christoph

    2016-09-01

    Organometallic halide perovskites CH3NH3BX3 (B= Pb, Sn, Ge; X = I, Br, Cl) have become one of the most promising semiconductors for solar cell applications, reaching power conversion efficiencies beyond 20%. Improving our ability to harness the full potential of organometal halide perovskites requires the development of more reliable synthesis routines of well defined, reproducible and defect free reference systems allowing to study the fundamental photo-physical processes. In this study we present size and band gap engineering for organo-lead perovskites crystallites with various shapes and sizes ranging from the 5 nm regime all the way to 1 cm. Colloidal nano-crystals, micro-crystlline particles as well as single crystals are demonstrated with excellent purity and control in shape and size are demonstrated. The structural, optical and photo-physical properties of these reference materials are investigated and analyzed as function of their size and shape.

  10. Atomic Resolution Imaging of Halide Perovskites.

    Science.gov (United States)

    Yu, Yi; Zhang, Dandan; Kisielowski, Christian; Dou, Letian; Kornienko, Nikolay; Bekenstein, Yehonadav; Wong, Andrew B; Alivisatos, A Paul; Yang, Peidong

    2016-12-14

    The radiation-sensitive nature of halide perovskites has hindered structural studies at the atomic scale. We overcome this obstacle by applying low dose-rate in-line holography, which combines aberration-corrected high-resolution transmission electron microscopy with exit-wave reconstruction. This technique successfully yields the genuine atomic structure of ultrathin two-dimensional CsPbBr3 halide perovskites, and a quantitative structure determination was achieved atom column by atom column using the phase information of the reconstructed exit-wave function without causing electron beam-induced sample alterations. An extraordinarily high image quality enables an unambiguous structural analysis of coexisting high-temperature and low-temperature phases of CsPbBr3 in single particles. On a broader level, our approach offers unprecedented opportunities to better understand halide perovskites at the atomic level as well as other radiation-sensitive materials.

  11. A review on visible light active perovskite-based photocatalysts.

    Science.gov (United States)

    Kanhere, Pushkar; Chen, Zhong

    2014-12-01

    Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (λ > 400 nm) active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3) structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development.

  12. Electronic and Ionic Transport Dynamics in Organolead Halide Perovskites.

    Science.gov (United States)

    Li, Dehui; Wu, Hao; Cheng, Hung-Chieh; Wang, Gongming; Huang, Yu; Duan, Xiangfeng

    2016-07-26

    Ion migration has been postulated as the underlying mechanism responsible for the hysteresis in organolead halide perovskite devices. However, the electronic and ionic transport dynamics and how they impact each other in organolead halide perovskites remain elusive to date. Here we report a systematic investigation of the electronic and ionic transport dynamics in organolead halide perovskite microplate crystals and thin films using temperature-dependent transient response measurements. Our study reveals that thermally activated ionic and electronic conduction coexist in perovskite devices. The extracted activation energies suggest that the electronic transport is easier, but ions migrate harder in microplates than in thin films, demonstrating that the crystalline quality and grain boundaries can fundamentally modify electronic and ionic transport in perovskites. These findings offer valuable insight on the electronic and ionic transport dynamics in organolead halide perovskites, which is critical for optimizing perovskite devices with reduced hysteresis and improved stability and efficiency.

  13. Synthesis of solid solutions of perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Dambekalne, M.Y.; Antonova, M.K.; Perro, I.T.; Plaude, A.V.

    1986-03-01

    The authors carry out thermographic studies, using a derivatograph, in order to understand the nature of the processes taking place during the synthesis of solid solutions of perovskites. Based on the detailed studies on the phase transformations occurring in the charges of the PSN-PMN solid solutions and on the selection of the optimum conditions for carrying out their synthesis, the authors obtained a powder containing a minimum quantity of the undesirable pyrochlore phase and by sintering it using the hot pressing method, they produced single phase ceramic specimens containing the perovskite phase alone with a density close to the theoretical value and showing zero apparent porosity and water absorption.

  14. Excited State Properties of Hybrid Perovskites.

    Science.gov (United States)

    Saba, Michele; Quochi, Francesco; Mura, Andrea; Bongiovanni, Giovanni

    2016-01-19

    Metal halide perovskites have come to the attention of the scientific community for the progress achieved in solar light conversion. Energy sustainability is one of the priorities of our society, and materials advancements resulting in low-cost but efficient solar cells and large-area lighting devices represent a major goal for applied research. From a basic point of view, perovskites are an exotic class of hybrid materials combining some merits of organic and inorganic semiconductors: large optical absorption, large mobilities, and tunable band gap together with the possibility to be processed in solution. When a novel class of promising semiconductors comes into the limelight, lively discussions ensue on the photophysics of band-edge excitations, because just the states close to the band edge are entailed in energy/charge transport and light emission. This was the case several decades ago for III-V semiconductors, it has been up to 10 years ago for organics, and it is currently the case for perovskites. Our aim in this Account is to rationalize the body of experimental evidence on perovskite photophysics in a coherent theoretical framework, borrowing from the knowledge acquired over the years in materials optoelectronics. A crucial question is whether photon absorption leads to a population of unbound, conductive free charges or instead excitons, neutral and insulating bound states created by Coulomb interaction just below the energy of the band gap. We first focus on the experimental estimates of the exciton binding energy (Eb): at room temperature, Eb is comparable to the thermal energy kBT in MAPbI3 and increases up to values 2-3kBT in wide band gap MAPbBr3 and MAPbCl3. Statistical considerations predict that these values, even though comparable to or larger than thermal energy, let free carriers prevail over bound excitons for all levels of excitation densities relevant for devices. The analysis of photophysics evidence confirms that all hybrid halide

  15. Research Update: Luminescence in lead halide perovskites

    Directory of Open Access Journals (Sweden)

    Ajay Ram Srimath Kandada

    2016-09-01

    Full Text Available Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  16. Partial oxidation of 2-propanol on perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Sumathi, R.; Viswanathan, B.; Varadarajan, T.K. [Indian Inst. of Tech., Madras (India). Dept. of Chemistry

    1998-12-31

    Partial oxidation of 2-propanol was carried out on AB{sub 1-x}B`{sub x}O{sub 3} (A=Ba, B=Pb, Ce, Ti; B`=Bi, Sb and Cu) type perovskite oxides. Acetone was the major product observed on all the catalysts. All the catalysts underwent partial reduction during the reaction depending on the composition of the reactant, nature of the B site cation and the extent of substitution at B site. The catalytic activity has been correlated with the reducibility of the perovskite oxides determined from Temperature Programmed Reduction (TPR) studies. (orig.)

  17. Research Update: Luminescence in lead halide perovskites

    Science.gov (United States)

    Srimath Kandada, Ajay Ram; Petrozza, Annamaria

    2016-09-01

    Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  18. Large area perovskite solar cell module

    Science.gov (United States)

    Cai, Longhua; Liang, Lusheng; Wu, Jifeng; Ding, Bin; Gao, Lili; Fan, Bin

    2017-01-01

    The recent dramatic rise in power conversion efficiencies (PCE) of perovskite solar cells has triggered intense research worldwide. However, their practical development is hampered by poor stability and low PCE values with large areas devices. Here, we developed a gas-pumping method to avoid pinholes and eliminate local structural defects over large areas of perovskite film, even for 5 × 5 cm2 modules, the PCE reached 10.6% and no significant degradation was found after 140 days of outdoor testing. Our approach enables the realization of high performance large-area PSCs for practical application.

  19. Nanoscale investigation of organic - inorganic halide perovskites

    Science.gov (United States)

    Cacovich, S.; Divitini, G.; Vrućinić, M.; Sadhanala, A.; Friend, R. H.; Sirringhaus, H.; Deschler, F.; Ducati, C.

    2015-10-01

    Over the last few years organic - inorganic halide perovskite-based solar cells have exhibited a rapid evolution, reaching certified power conversion efficiencies now surpassing 20%. Nevertheless the understanding of the optical and electronic properties of such systems on the nanoscale is still an open problem. In this work we investigate two model perovskite systems (based on iodine - CH3NH3PbI3 and bromine - CH3NH3PbBr3), analysing the local elemental composition and crystallinity and identifying chemical inhomogeneities.

  20. 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

    2016-09-19

    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.

  1. 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

    2016-09-01

    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.

  2. 高铁酸钾/紫外光协同体系降解对硝基苯酚研究%Study of the degradation of p-nitrophenol by synergism system of potassium ferrate and UV light

    Institute of Scientific and Technical Information of China (English)

    王佩佩; 彭书传; 朱承驻; 胡喆

    2015-01-01

    Degradation of p‐nitrophenol in simulated wastewater was studied by potassium ferrate com‐bined with 254 nm ultraviolet(UV) light .The effect of the parameters of potassium ferrate dose ,p‐nitrophenol initial concentration ,solution pH value ,degradation time on the degradation efficiency of CODCr of p‐nitrophenol was discussed ,and the processing parameters were obtained by optimized or‐thogonal experiment .The degradation products were analyzed by UV spectrum and its degradation mechanism was also proposed .The results showed that p‐nitrophenol was effectively degraded by po‐tassium ferrate combined with 254 nm UV light .When the mole ratio of K2 FeO4 to nitrobenzene was 9∶1 ,the p‐nitrophenol initial concentration was 30 mg/L ,the initial pH value was 11 and the degra‐dation time was 30 min ,the degradation efficiency of CODCr reached above 85.71% .The degradation process was in accordance with the second order reaction and the kinetic rate constant of the reaction w as 6.49 × 10-5 L/(mol · s) .%文章采用高铁酸钾/紫外光(254 nm )协同体系降解对硝基苯酚模拟废水;考察了高铁酸钾投加量、对硝基苯酚初始质量浓度、pH值、降解时间等参数对CODCr降解率的影响,通过正交试验优化此方法降解对硝基苯酚的工艺参数,并对产物进行了紫外光谱扫描分析,初步探讨降解机理。结果表明,高铁酸钾/254 nm紫外光协同体系可有效降解对硝基苯酚;当高铁酸钾与对硝基苯酚的摩尔比为9∶1,对硝基苯酚质量浓度为30 mg/L ,pH值为11及降解时间为30 min时,CODCr降解率可达85.71%。降解较好地符合二级反应,速率常数为6.49×10-5 L/(mol · s)。

  3. Improving the Stability and Performance of Perovskite Light-Emitting Diodes by Thermal Annealing Treatment.

    Science.gov (United States)

    Yu, Jae Choul; Kim, Dae Woo; Kim, Da Bin; Jung, Eui Dae; Park, Jong Hyun; Lee, Ah-Young; Lee, Bo Ram; Di Nuzzo, Daniele; Friend, Richard H; Song, Myoung Hoon

    2016-08-01

    A perovskite LED with a perovskite film treated under optimum thermal annealing conditions exhibits a significantly enhanced long-term stability with full coverage of the green electroluminescence emission due to the highly uniform morphology of the perovskite film.

  4. Material and Device Stability in Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Hui-Seon; Seo, Ja-Young; Park, Nam-Gyu

    2016-09-22

    Organic-inorganic halide perovskite solar cells have attracted great attention because of their superb efficiency reaching 22 % and low-cost, facile fabrication processing. Nevertheless, stability issues in perovskite solar cells seem to block further advancements toward commercialization. Thus, device stability is one of the important topics in perovskite solar cell research. In the beginning, the poor moisture resistivity of the perovskite layer was considered as a main problem that hindered further development of perovskite solar cells, which encouraged engineering of the perovskite or protection of the perovskite by a buffer layer. Soon after, other parameters affecting long-term stability were sequentially found and various attempts have been made to enhance intrinsic and extrinsic stability. Here we review the recent progresses addressing stability issues in perovskite solar cells. In this report, we investigated factors affecting stability from material and device points of view. To gain a better understanding of the stability of the bulk perovskite material, decomposition mechanisms were investigated in relation to moisture, photons, and heat. Stability of full device should also be carefully examined because its stability is dependent not only on bulk perovskite but also on the interfaces and selective contacts. In addition, ion migration and current-voltage hysteresis were found to be closely related to stability.

  5. Properties of Perovskites and other oxides

    NARCIS (Netherlands)

    Müller, K.A.; Kool, T.W.

    2010-01-01

    In this book some 50 papers published by K A Müller as author or co-author over several decades, amplified by more recent work mainly by T W Kool with collaborators, are reproduced. The main subject is Electron Paramagnetic Resonance (EPR) applied to the study of perovskites and other oxides with re

  6. Calculated optical absorption of different perovskite phases

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel

    2015-01-01

    We present calculations of the optical properties of a set of around 80 oxides, oxynitrides, and organometal halide cubic and layered perovskites (Ruddlesden-Popper and Dion-Jacobson phases) with a bandgap in the visible part of the solar spectrum. The calculations show that for different classes...

  7. Centrifugal Casting of Tubular Perovskite Membranes

    NARCIS (Netherlands)

    Mertins, Frederic H.B.; Kruidhof, Henk; Bouwmeester, Henny J.M.

    2005-01-01

    Dense tubular membranes were produced by centrifugal casting of an aqueous suspension, containing powder particles of the mixed-conducting perovskite La0.5Sr0.5CoO3−δ and a dispersant. The resulting green bodies were dried and sintered to produce tubes with a maximum length of 12 cm, having a relat

  8. Tilts and Ionic Shifts in Rhombohedral Perovskites

    NARCIS (Netherlands)

    Noheda, Beatriz; Duan, Ning; Cereceda, Noé; Gonzalo, Julio A.

    1998-01-01

    We make a comparative analysis of rhombohedral perovskites (ABO3) with/without oxygen rotations and ionic shifts, within the framework of a generalised effective field approach. We analyse available data on LaAlO3 and LiTaO3 and new data on Zr-rich PZT, examples of three different ways of structural

  9. Hybrid solar cells : Perovskites under the Sun

    NARCIS (Netherlands)

    Loi, Maria Antonietta; Hummelen, Jan C.

    2013-01-01

    Mixed-halide organic–inorganic hybrid perovskites are reported to display electron–hole diffusion lengths over 1 μm. This observation provides important insight into the charge-carrier dynamics of this class of semiconductors and increases the expectations for highly efficient and cheap solar cells.

  10. Electro-optics of perovskite solar cells

    Science.gov (United States)

    Lin, Qianqian; Armin, Ardalan; Nagiri, Ravi Chandra Raju; Burn, Paul L.; Meredith, Paul

    2015-02-01

    Organohalide-perovskite solar cells have emerged as a leading next-generation photovoltaic technology. However, despite surging efficiencies, many questions remain unanswered regarding the mechanisms of operation. Here we report a detailed study of the electro-optics of efficient CH3NH3PbI3-perovskite-only planar devices. We report the dielectric constants over a large frequency range. Importantly, we found the real part of the static dielectric constant to be ∼70, from which we estimate the exciton-binding energy to be of order 2 meV, which strongly indicates a non-excitonic mechanism. Also, Jonscher's Law behaviour was consistent with the perovskite having ionic character. Accurate knowledge of the cell's optical constants allowed improved modelling and design, and using this information we fabricated an optimized device with an efficiency of 16.5%. The optimized devices have ∼100% spectrally flat internal quantum efficiencies and minimal bimolecular recombination. These findings establish systematic design rules to achieve silicon-like efficiencies in simple perovskite solar cells.

  11. High performance magnetocaloric perovskites for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bahl, Christian R. H.; Velazquez, David; Nielsen, Kaspar K.

    2012-01-01

    We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials. Re...

  12. Recent progress in stability of perovskite solar cells

    Science.gov (United States)

    Qin, Xiaojun; Zhao, Zhiguo; Wang, Yidan; Wu, Junbo; Jiang, Qi; You, Jingbi

    2017-01-01

    Perovskite solar cells have attracted significant attention in just the past few years in solar cell research fields, where the power conversion efficiency was beyond 22.1%. Now, the most important challenge for perovskite solar cells in practical applications is the stability issue. In this mini-review, we will summarize the degradation mechanism of perovskite solar cells, including the perovskite material itself and also the interfaces. While we also provide our opinion on improving the stability of perovskite solar cells. Project supported by China Huaneng Group Project High Performance Perovskite Solar Cells (No. TW-15-HJK01), the National Key Research and Development Program of China (No. 2016YFB0700700), the National 1000 Young Talent Awards, and the National Natural Science Foundation of China (No. 61574133).

  13. Neutral- and Multi-Colored Semitransparent Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Kyu-Tae Lee

    2016-04-01

    Full Text Available In this review, we summarize recent works on perovskite solar cells with neutral- and multi-colored semitransparency for building-integrated photovoltaics and tandem solar cells. The perovskite solar cells exploiting microstructured arrays of perovskite “islands” and transparent electrodes—the latter of which include thin metallic films, metal nanowires, carbon nanotubes, graphenes, and transparent conductive oxides for achieving optical transparency—are investigated. Moreover, the perovskite solar cells with distinctive color generation, which are enabled by engineering the band gap of the perovskite light-harvesting semiconductors with chemical management and integrating with photonic nanostructures, including microcavity, are discussed. We conclude by providing future research directions toward further performance improvements of the semitransparent perovskite solar cells.

  14. Neutral- and Multi-Colored Semitransparent Perovskite Solar Cells.

    Science.gov (United States)

    Lee, Kyu-Tae; Guo, L Jay; Park, Hui Joon

    2016-04-11

    In this review, we summarize recent works on perovskite solar cells with neutral- and multi-colored semitransparency for building-integrated photovoltaics and tandem solar cells. The perovskite solar cells exploiting microstructured arrays of perovskite "islands" and transparent electrodes-the latter of which include thin metallic films, metal nanowires, carbon nanotubes, graphenes, and transparent conductive oxides for achieving optical transparency-are investigated. Moreover, the perovskite solar cells with distinctive color generation, which are enabled by engineering the band gap of the perovskite light-harvesting semiconductors with chemical management and integrating with photonic nanostructures, including microcavity, are discussed. We conclude by providing future research directions toward further performance improvements of the semitransparent perovskite solar cells.

  15. Applications of cesium in the perovskite solar cells

    Science.gov (United States)

    Ye, Fengjun; Yang, Wenqiang; Luo, Deying; Zhu, Rui; Gong, Qihuang

    2017-01-01

    Perovskite solar cells have experienced an unprecedented rapid development in the power conversion efficiency (PCE) during the past 7 years, and the record PCE has been already comparable to the traditional polycrystalline silicon solar cells. Presently, it is more urgent to address the challenge on device stability for the future commercial application. Recently, the inorganic cesium lead halide perovskite has been intensively studied as one of the alternative candidates to improve device stability through controlling the phase transition. The cesium (Cs)-doped perovskites show more superior stability comparing with organic methylammonium (MA) lead halide perovskite or formamidinium (FA) lead halide perovskite. Here, recent progress of the inorganic cesium application in organic–inorganic perovskite solar cells (PSCs) is highlighted from the viewpoints of the device efficiency and the device stability. Project supported by the 973 Program of China (No. 2015CB932203), the National Natural Science Foundation of China (Nos. 61377025, 91433203), and the Young 1000 Talents Global Recruitment Program of China.

  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. 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-measurements ...

  18. A Physics-based Analytical Model for Perovskite Solar Cells

    OpenAIRE

    Sun, Xingshu; Asadpour, Reza; Nie, Wanyi; Mohite, Aditya D.; Alam, Muhammad A.

    2015-01-01

    Perovskites are promising next-generation absorber materials for low-cost and high-efficiency solar cells. Although perovskite cells are configured similar to the classical solar cells, their operation is unique and requires development of a new physical model for characterization, optimization of the cells, and prediction of the panel performance. In this paper, we develop such a physics-based analytical model to describe the operation of different types of perovskite solar cells, explicitly...

  19. 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.

  20. Perovskite solar cells: Shedding light on film crystallization

    Science.gov (United States)

    Bakr, Osman M.; Mohammed, Omar F.

    2017-06-01

    A study on the formation of methylammonium lead iodide perovskite films reveals that light illumination influences the crystallization kinetics, therefore affecting the final photovoltaic performance of these materials.

  1. Post-perovskite Transition in Anti-structure.

    Science.gov (United States)

    Wang, Bosen; Ohgushi, Kenya

    2016-11-30

    The discovery of the post-perovskite transition, which is the structural transition from the perovskite to post-perovskite structure in MgSiO3 under pressure, has aroused great interests in geosciences. Despite of previous extensive studies, key factors of the post-perovsktie transition are still under hot debate primarily due to the big difficulty in performing systematic experiments under extreme conditions. Hence, search for new materials showing the post-perovskite transition under ambient pressure has been highly expected. We here report a new-type of materials Cr3AX (A = Ga, Ge; X = C, N), which exhibits the post-perovskite transition as a function of "chemical pressure" at ambient physical pressure. The detailed structural analysis indicates that the tolerance factor, which is the measure of the ionic radius mismatch, plays the key role in the post-perovskite transition. Moreover, we found a tetragonal perovskite structure with loss of inversion symmetry between the cubic perovskite and orthorhombic post-perovskite structures. This finding stimulates a search for a ferroelectric state in MgSiO3.

  2. Post-perovskite Transition in Anti-structure

    Science.gov (United States)

    Wang, Bosen; Ohgushi, Kenya

    2016-11-01

    The discovery of the post-perovskite transition, which is the structural transition from the perovskite to post-perovskite structure in MgSiO3 under pressure, has aroused great interests in geosciences. Despite of previous extensive studies, key factors of the post-perovsktie transition are still under hot debate primarily due to the big difficulty in performing systematic experiments under extreme conditions. Hence, search for new materials showing the post-perovskite transition under ambient pressure has been highly expected. We here report a new-type of materials Cr3AX (A = Ga, Ge; X = C, N), which exhibits the post-perovskite transition as a function of “chemical pressure” at ambient physical pressure. The detailed structural analysis indicates that the tolerance factor, which is the measure of the ionic radius mismatch, plays the key role in the post-perovskite transition. Moreover, we found a tetragonal perovskite structure with loss of inversion symmetry between the cubic perovskite and orthorhombic post-perovskite structures. This finding stimulates a search for a ferroelectric state in MgSiO3.

  3. Molecular dynamics of MgSiO3 perovskite melting

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Yang Xiang-Dong; Zhang Hong; Cai Ling-Cang

    2006-01-01

    The melting curve of MgSiO3 perovskite is simulated using molecular dynamics simulations method at high pressure. It is shown that the simulated equation of state of MgSiO3 perovskite is very successful in reproducing accurately the experimental data. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite reproduces the stability of the orthorhombic perovskite phase up to high pressure of 13OGPa at ambient temperature, consistent with the theoretical data of the other calculations. It is shown that its transformation to the cubic phase and melting at high pressure and high temperature are in agreement with recent experiments.

  4. Elastic anisotropy of experimental analogues of perovskite and post-perovskite help to interpret D'' diversity.

    Science.gov (United States)

    Yoneda, Akira; Fukui, Hiroshi; Xu, Fang; Nakatsuka, Akihiko; Yoshiasa, Akira; Seto, Yusuke; Ono, Kenya; Tsutsui, Satoshi; Uchiyama, Hiroshi; Baron, Alfred Q R

    2014-03-27

    Recent studies show that the D'' layer, just above the Earth's core-mantle boundary, is composed of MgSiO3 post-perovskite and has significant lateral inhomogeneity. Here we consider the D'' diversity as related to the single-crystal elasticity of the post-perovskite phase. We measure the single-crystal elasticity of the perovskite Pbnm-CaIrO3 and post-perovskite Cmcm-CaIrO3 using inelastic X-ray scattering. These materials are structural analogues to same phases of MgSiO3. Our results show that Cmcm-CaIrO3 is much more elastically anisotropic than Pbnm-CaIrO3, which offers an explanation for the enigmatic seismic wave velocity jump at the D'' discontinuity. Considering the relation between lattice preferred orientation and seismic anisotropy in the D'' layer, we suggest that the c axis of post-perovskite MgSiO3 aligns vertically beneath the Circum-Pacific rim, and the b axis vertically beneath the Central Pacific.

  5. Organohalide Perovskites for Solar Energy Conversion.

    Science.gov (United States)

    Lin, Qianqian; Armin, Ardalan; Burn, Paul L; Meredith, Paul

    2016-03-15

    Lead-based organohalide perovskites have recently emerged as arguably the most promising of all next generation thin film solar cell technologies. Power conversion efficiencies have reached 20% in less than 5 years, and their application to other optoelectronic device platforms such as photodetectors and light emitting diodes is being increasingly reported. Organohalide perovskites can be solution processed or evaporated at low temperatures to form simple thin film photojunctions, thus delivering the potential for the holy grail of high efficiency, low embedded energy, and low cost photovoltaics. The initial device-driven "perovskite fever" has more recently given way to efforts to better understand how these materials work in solar cells, and deeper elucidation of their structure-property relationships. In this Account, we focus on this element of organohalide perovskite chemistry and physics in particular examining critical electro-optical, morphological, and architectural phenomena. We first examine basic crystal and chemical structure, and how this impacts important solar-cell related properties such as the optical gap. We then turn to deeper electronic phenomena such as carrier mobilities, trap densities, and recombination dynamics, as well as examining ionic and dielectric properties and how these two types of physics impact each other. The issue of whether organohalide perovskites are predominantly nonexcitonic at room temperature is currently a matter of some debate, and we summarize the evidence for what appears to be the emerging field consensus: an exciton binding energy of order 10 meV. Having discussed the important basic chemistry and physics we turn to more device-related considerations including processing, morphology, architecture, thin film electro-optics and interfacial energetics. These phenomena directly impact solar cell performance parameters such as open circuit voltage, short circuit current density, internal and external quantum efficiency

  6. CFS氧化降解偶氮染料活性黑RB5%Degradation of azo dye C.I. Reactive Black 5 by composite ferrate solution

    Institute of Scientific and Technical Information of China (English)

    张彦平; 许国仁; 李圭白

    2008-01-01

    研究了复合高铁酸盐溶液(CFS)氧化降解活性黑(RB5)染料废水的反应条件和降解机理.结果表明:CFS氧化降解RB5的最佳pH范围为pH<10,并且在该范围内Fe(VI)的反应速率较快.当pH=8~9,CFS投加量为20 mg·L-1时,氧化反应5 min和20 min时,RB5的脱色率分别为80%和95%.对TOC和COD的去除实验表明,在氧化反应过程中存在有机分子的矿化反应,但矿化速率远低于脱色反应速率.UV-Vis和FTIR结果表明,染料分子中的偶氮基团能被Fe(VI)氧化破坏,并且处理后样品中RB5的特征红外吸收峰消失,说明了染料分子中部分苯环和萘环被破坏,从而使得染料废水的毒性降低、可生化性提高.因此,CFS作为一种高效、低廉的强氧化剂,为染料工业废水的处理提供了一个可行的方法.%Composite ferrate solution(CFS)was used directly in oxidation of ago dye wastewater of C.I.Reactive Black 5(RB5).The optimal oxidation conditions and degradation mechanism were investigated.The results indicated that the optimal pH for the oxidation was pH<10,and Fe(VI)had higher reactivity in this pH range.For example.with the CFS dosage of 20 mg·L-1 at pH=8~9,about 80% and 95% RB5 had been discolored at 5 min and 20 min.respectively.TOC and COD removal experiments indicated that the organic molecules could be mineralized, but the mineralization rate was much slower than the decolorization rate.UV-Vis and FT-IR results showed that the azo groups could be broken by the oxidation of Fe(VI),and almost all the characteristic absorption bands of RB5 disappeared which indicates the benzene and naphthalene structure had been destructed.The azo dye wastewater treated by CFS has lower toxicity and improved biodegradability.As a strong oxidant with lower cost,CFS has supplied a feasible choice for the treatment of ago dye in industrial wastewater.

  7. Metal halide perovskite nanomaterials: synthesis and applications.

    Science.gov (United States)

    Ha, Son-Tung; Su, Rui; Xing, Jun; Zhang, Qing; Xiong, Qihua

    2017-04-01

    Nanomaterials refer to those with at least one dimension being at the nanoscale (i.e. applications. The different synthesis approaches and growth mechanisms will be discussed along with their novel characteristics and applications. Taking perovskite quantum dots as an example, the quantum confinement effect and high external quantum efficiency are among these novel properties and their excellent performance in applications, such as single photon emitters and LEDs, will be discussed. Understanding the mechanism behind the formation of these nanomaterial forms of perovskite will help researchers to come up with effective strategies to combat the emerging challenges of this family of materials, such as stability under ambient conditions and toxicity, towards next generation applications in photovoltaics and optoelectronics.

  8. Perovskite Materials: Solar Cell and Optoelectronic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bin [ORNL; Geohegan, David B [ORNL; Xiao, Kai [ORNL

    2017-01-01

    Hybrid organometallic trihalide perovskites are promising candidates in the applications for next-generation, high-performance, low-cost optoelectronic devices, including photovoltaics, light emitting diodes, and photodetectors. Particularly, the solar cells based on this type of materials have reached 22% lab scale power conversion efficiency in only about seven years, comparable to the other thin film photovoltaic technologies. Hybrid perovskite materials not only exhibit superior optoelectronic properties, but also show many interesting physical properties such as ion migration and defect physics, which may allow the exploration of more device functionalities. In this article, the fundamental understanding of the interrelationships between crystal structure, electronic structure, and material properties is discussed. Various chemical synthesis and processing methods for superior device performance in solar cells and optoelectronic devices are reviewed.

  9. Ferroelectric perovskite nanopowders obtained by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Izabela Szafraniak-Wiza

    2010-09-01

    Full Text Available Simple perovskite nanopowders were fabricated by mechanochemical synthesis. High-energy milling process of respective oxides, leading to production of ferroelectric perovskites, was carefully investigated and characterized by X-ray diffraction, electron microscopy and X-ray excited photoelectron spectroscopy. It has been found that: (i the powder consists of loosely packed grains with a broad distribution of sizes between a few nm and 45 nm, (ii the grains possess core/shell structure, (iii the grain core of sizes larger than about 20 nm exhibits well developed crystalline structure, (iv the grains are coated by structurally disordered (amorphous shell. Intermediate phases have been found in the process of PbTiO3 mechanosynthesis only. The obtained nanopowders were used for preparation of dense ceramics.

  10. Synthesis of a polar ordered oxynitride perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Vadapoo, Rajasekarakumar; Ahart, Muhtar; Somayazulu, Maddury; Holtgrewe, Nicholas; Meng, Yue; Konopkova, Zuzana; Hemley, Russell J.; Cohen, R. E.

    2017-06-01

    For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen is replaced by nitrogen, but a polar ordered oxynitride has never been demonstrated. Caracas and Cohen [Appl. Phys. Lett. 91, 092902 (2007)] studied possible ordered polar oxynitrides within density-functional theory (DFT) and found a few candidates that were predicted to be insulating and at least metastable. YSi O 2 N stood out with huge predicted polarization and nonlinear optic coefficients. In this study, we demonstrate the synthesis of perovskite-structured YSi O 2 N by using a combination of a diamond-anvil cell and in situ laser-heating techniques. Subsequent in situ x-ray diffraction, second-harmonic generation, and Raman-scattering measurements confirm that it is polar and a strong nonlinear optical material, with structure and properties similar to those predicted by DFT.

  11. d0 Perovskite-Semiconductor Electronic Structure

    OpenAIRE

    Bistritzer, R.; Khalsa, G.; MacDonald, A. H.

    2010-01-01

    We address the low-energy effective Hamiltonian of electron doped d0 perovskite semiconductors in cubic and tetragonal phases using the k*p method. The Hamiltonian depends on the spin-orbit interaction strength, on the temperature-dependent tetragonal distortion, and on a set of effective-mass parameters whose number is determined by the symmetry of the crystal. We explain how these parameters can be extracted from angle resolved photo-emission, Raman spectroscopy, and magneto-transport measu...

  12. High performance magnetocaloric perovskites for magnetic refrigeration

    OpenAIRE

    Velázquez, David

    2012-01-01

    We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials. Reasonable correspondence is found between experiments and a 2D numerical model, using the measured magnetocaloric properties of the two materials as input. © 2012 American Institute of Physics.

  13. The photophysics of perovskite solar cells

    Science.gov (United States)

    Sum, Tze Chien

    2014-09-01

    Solution-processed hybrid organic-inorganic perovskite solar cells, a newcomer to the photovoltaic arena, have taken the field by storm with their extraordinary power conversion efficiencies exceeding 17%. In this paper, the photophysics and the latest findings on the carrier dynamics and charge transfer mechanisms in this new class of photovoltaic material will be examined and distilled. Some open photophysics questions will also be discussed.

  14. Resistance switching memory in perovskite oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Z.B., E-mail: zbyan@nju.edu.cn; Liu, J.-M., E-mail: liujm@nju.edu.cn

    2015-07-15

    The resistance switching behavior has recently attracted great attentions for its application as resistive random access memories (RRAMs) due to a variety of advantages such as simple structure, high-density, high-speed and low-power. As a leading storage media, the transition metal perovskite oxide owns the strong correlation of electrons and the stable crystal structure, which brings out multifunctionality such as ferroelectric, multiferroic, superconductor, and colossal magnetoresistance/electroresistance effect, etc. The existence of rich electronic phases, metal–insulator transition and the nonstoichiometric oxygen in perovskite oxide provides good platforms to insight into the resistive switching mechanisms. In this review, we first introduce the general characteristics of the resistance switching effects, the operation methods and the storage media. Then, the experimental evidences of conductive filaments, the transport and switching mechanisms, and the memory performances and enhancing methods of perovskite oxide based filamentary RRAM cells have been summarized and discussed. Subsequently, the switching mechanisms and the performances of the uniform RRAM cells associating with the carrier trapping/detrapping and the ferroelectric polarization switching have been discussed. Finally, the advices and outlook for further investigating the resistance switching and enhancing the memory performances are given.

  15. 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%.

  16. 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%.

  17. Perovskite-related oxynitrides in photocatalysis.

    Science.gov (United States)

    Pokrant, Simone; Maegli, Alexandra E; Chiarello, Gian Luca; Weidenkaff, Anke

    2013-01-01

    Over the last decades photocatalytic water splitting has become of increasing importance for fundamental and applied research, since the direct conversion of sunlight into chemical energy via the production of H2 has the potential to contribute to the world's energy needs without CO2 generation. One of the unsolved challenges consists of finding a highly efficient photocatalyst that is cheap, environmentally friendly, contains exclusively abundant elements, is (photo)chemically stable and absorbs visible light. Photocatalytic efficiency is closely connected to both structural properties like crystallinity, particle size and surface area and to electronic properties like the band gap and the quantum efficiency. Hence extensive control over a large parameter field is necessary to design a good photocatalyst. A material class where the structure-composition-property relations and the influence of substitution effects are well studied is the perovskite-type family of compounds. The perovskite-related oxynitrides belong to this very flexible compound family where many of the necessary characteristics for a photocatalyst are already given and some of the intrinsic properties like the band gap can be tuned within the same crystal structure by substitution. In this work we present materials' design concepts to improve the photocatalytic efficiency of a perovskite-type catalyst and describe their effects on the photocatalytic activity.

  18. Surface Restructuring of Hybrid Perovskite Crystals

    KAUST Repository

    Banavoth, Murali

    2016-11-07

    Hybrid perovskite crystals have emerged as an important class of semiconductors because of their remarkable performance in optoelectronics devices. The interface structure and chemistry of these crystals are key determinants of the device\\'s performance. Unfortunately, little is known about the intrinsic properties of the surfaces of perovskite materials because extrinsic effects, such as complex microstructures, processing conditions, and hydration under ambient conditions, are thought to cause resistive losses and high leakage current in solar cells. We reveal the intrinsic structural and optoelectronic properties of both pristinely cleaved and aged surfaces of single crystals. We identify surface restructuring on the aged surfaces (visualized on the atomic-scale by scanning tunneling microscopy) that lead to compositional and optical bandgap changes as well as degradation of carrier dynamics, photocurrent, and solar cell device performance. The insights reported herein clarify the key variables involved in the performance of perovskite-based solar cells and fabrication of high-quality surface single crystals, thus paving the way toward their future exploitation in highly efficient solar cells.

  19. Intriguing Optoelectronic Properties of Metal Halide Perovskites.

    Science.gov (United States)

    Manser, Joseph S; Christians, Jeffrey A; Kamat, Prashant V

    2016-11-09

    A new chapter in the long and distinguished history of perovskites is being written with the breakthrough success of metal halide perovskites (MHPs) as solution-processed photovoltaic (PV) absorbers. The current surge in MHP research has largely arisen out of their rapid progress in PV devices; however, these materials are potentially suitable for a diverse array of optoelectronic applications. Like oxide perovskites, MHPs have ABX3 stoichiometry, where A and B are cations and X is a halide anion. Here, the underlying physical and photophysical properties of inorganic (A = inorganic) and hybrid organic-inorganic (A = organic) MHPs are reviewed with an eye toward their potential application in emerging optoelectronic technologies. Significant attention is given to the prototypical compound methylammonium lead iodide (CH3NH3PbI3) due to the preponderance of experimental and theoretical studies surrounding this material. We also discuss other salient MHP systems, including 2-dimensional compounds, where relevant. More specifically, this review is a critical account of the interrelation between MHP electronic structure, absorption, emission, carrier dynamics and transport, and other relevant photophysical processes that have propelled these materials to the forefront of modern optoelectronics research.

  20. Defect Tolerance in Methylammonium Lead Triiodide Perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Steirer, K. Xerxes; Schulz, Philip; Teeter, Glenn; Stevanovic, Vladan; Yang, Mengjin; Zhu, Kai; Berry, Joseph J.

    2016-08-12

    Photovoltaic applications of perovskite semiconductor material systems have generated considerable interest in part because of predictions that primary defect energy levels reside outside the bandgap. We present experimental evidence that this enabling material property is present in the halide-lead perovskite, CH3NH3PbI3 (MAPbI3), consistent with theoretical predictions. By performing X-ray photoemission spectroscopy, we induce and track dynamic chemical and electronic transformations in the perovskite. These data show compositional changes that begin immediately with exposure to X-ray irradiation, whereas the predominant electronic structure of the thin film on compact TiO2 appears tolerant to the formation of compensating defect pairs of VI and VMA and for a large range of I/Pb ratios. Changing film composition is correlated with a shift of the valence-band maximum only as the halide-lead ratio drops below 2.5. This delay is attributed to the invariance of MAPbI3 electronic structure to distributed defects that can significantly transform the electronic density of states only when in high concentrations.

  1. High Efficiency Pb-In Binary Metal Perovskite Solar Cells.

    Science.gov (United States)

    Wang, Zhao-Kui; Li, Meng; Yang, Ying-Guo; Hu, Yun; Ma, Heng; Gao, Xing-Yu; Liao, Liang-Sheng

    2016-08-01

    Mixed Pb-In perovskite solar cells are fabricated by using lead(II) chloride and indium(III) chloride with methylammonium iodide. A maximum power conversion efficiency as high as 17.55% is achieved owing to the high quality of perovskites with multiple ordered crystal orientations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Seismic detection of post-perovskite inside the Earth

    NARCIS (Netherlands)

    Cobden, Laura; Thomas, Christine; Trampert, Jeannot

    2015-01-01

    Since 2004, we have known that perovskite, the most abundant mineral in the lower mantle, has the capacity to transform to a denser structure, postperovskite, if subjected to sufficiently high temperature and pressure. But does post-perovskite exist inside the Earth? And if it does, do we have the r

  3. Two Dimensional Organometal Halide Perovskite Nanorods with Tunable Optical Properties.

    Science.gov (United States)

    Aharon, Sigalit; Etgar, Lioz

    2016-05-11

    Organo-metal halide perovskite is an efficient light harvester in photovoltaic solar cells. Organometal halide perovskite is used mainly in its "bulk" form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this paper, we present facile low-temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g., octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. The 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light-emitting diodes, lasing, solar cells, and sensors.

  4. Solution Chemistry Engineering toward High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Zhao, Yixin; Zhu, Kai

    2014-12-04

    Organic and inorganic hybrid perovskites (e.g., CH3NH3PbI3) have emerged as a revolutionary class of light-absorbing semiconductors that has demonstrated a rapid increase in efficiency within a few years of active research. Controlling perovskite morphology and composition has been found critical to developing high-performance perovskite solar cells. The recent development of solution chemistry engineering has led to fabrication of greater than 15-17%-efficiency solar cells by multiple groups, with the highest certified 17.9% efficiency that has significantly surpassed the best-reported perovskite solar cell by vapor-phase growth. In this Perspective, we review recent progress on solution chemistry engineering processes and various control parameters that are critical to the success of solution growth of high-quality perovskite films. We discuss the importance of understanding the impact of solution-processing parameters and perovskite film architectures on the fundamental charge carrier dynamics in perovskite solar cells. The cost and stability issues of perovskite solar cells will also be discussed.

  5. Morphological Optimization of Perovskite Thin Films via Dynamic Zone Annealing

    Science.gov (United States)

    Sun, Yan; Wang, Kai; Gong, Xiong; Karim, Alamgir

    2015-03-01

    Organolead Halide Perovskites have been proved to be excellent candidates for application in low-cost high-efficient solar cells owing to their superior desired optical and electrical properties, as well as compatibility with low-temperature solution-processed manufacturing. However, most perovskites applications in photovoltaics require high quality perovskite films. Although tremendous works on tuning perovskite film morphology have been reported previously, it is still a challenge to realize high quality perovskite film with controllable film uniformity and surface coverage, neither the mechanisms in the formation of perovskite. To address the issues above, here we demonstrate the effect of Dynamic Zone Annealing (DZA) on perovskite morphologies, which is proved as an efficient method to control the structure and morphology in crystalline polymer and block copolymers. Via applying the DZA method, the mechanism in perovskite film formation is studied. Furthermore, by optimizing DZA parameter such as maximum temperature, temperature gradient and zone velocity to control dendritic morphology and the grain growth, enhanced device performance was realized eventually. Equal contribution.

  6. Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Lee, Yong Hui; Luo, Jingshan; Son, Min-Kyu; Gao, Peng; Cho, Kyung Taek; Seo, Jiyoun; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2016-05-01

    The Al2 O3 passivation layer is beneficial for mesoporous TiO2 -based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of the perovskite layer during post-annealing.

  7. Isothermal precipitation and growth process of perovskite phase in oxidized titanium bearing slag

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-yu; WANG Xue-wen; HE Yue-hui; LOU Tai-ping; SUI Zhi-tong

    2008-01-01

    The isothermal precipitating behavior of perovskite phase in oxidized titanium bearing slag was studied by quenching method. The kinetics of precipitating process and crystal growth of perovskite phase was analyzed. The results show that the precipitating and growth of perovskite are non-equilibrium process at the beginning of isothermal treatment. There are two factors influencing the growth rate of perovskite phase on non-equilibrium condition, one is the supersaturation concentration of perovskite and the other is the coarsening arising from the growth of larger perovskite at the expense of smaller ones. The precipitation kinetics of perovskite phase can be nearly described by the JMAK equation.

  8. CH3 NH3 PbBr3 -CH3 NH3 PbI3 Perovskite-Perovskite Tandem Solar Cells with Exceeding 2.2 V Open Circuit Voltage.

    Science.gov (United States)

    Heo, Jin Hyuck; Im, Sang Hyuk

    2016-07-01

    Perovskite-perovskite tandem solar cells with open-circuit voltages of over 2.2 V are reported. These cost-effective, solution-processible perovskite hybrid tandem solar cells with high open-circuit voltages are fabricated by the simple lamination of a front planar MAPbBr3 perovskite cell and a back MAPbI3 planar perovskite solar cell.

  9. Self-Assembled PbSe Nanowire:Perovskite Hybrids.

    Science.gov (United States)

    Yang, Zhenyu; Yassitepe, Emre; Voznyy, Oleksandr; Janmohamed, Alyf; Lan, Xinzheng; Levina, Larissa; Comin, Riccardo; Sargent, Edward H

    2015-12-02

    Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  10. Performance of planar heterojunction perovskite solar cells under light concentration

    Science.gov (United States)

    Alnuaimi, Aaesha; Almansouri, Ibraheem; Nayfeh, Ammar

    2016-11-01

    In this work, we present 2D simulation of planar heterojunction perovskite solar cells under high concentration using physics-based TCAD. The performance of planar perovskite heterojunction solar cells is examined up to 1000 suns. We analyze the effect of HTM mobility and band structure, surface recombination velocities at interfaces and the effect of series resistance under concentrated light. The simulation results revealed that the low mobility of HTM material limits the improvement in power conversation efficiency of perovskite solar cells under concentration. In addition, large band offset at perovskite/HTM interface contributes to the high series resistance. Moreover, losses due to high surface recombination at interfaces and the high series resistance deteriorate significantly the performance of perovskite solar cells under concentration.

  11. Highly efficient light management for perovskite solar cells

    Science.gov (United States)

    Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

    2016-01-01

    Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.

  12. Highly efficient light management for perovskite solar cells

    CERN Document Server

    Wang, Dong-Lin; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

    2015-01-01

    Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.

  13. 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.

  14. Planar-integrated single-crystalline perovskite photodetectors

    KAUST Repository

    Saidaminov, Makhsud I.

    2015-11-09

    Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors.

  15. Integrating perovskite solar cells into a flexible fiber.

    Science.gov (United States)

    Qiu, Longbin; Deng, Jue; Lu, Xin; Yang, Zhibin; Peng, Huisheng

    2014-09-22

    Perovskite solar cells have triggered a rapid development of new photovoltaic devices because of high energy conversion efficiencies and their all-solid-state structures. To this end, they are particularly useful for various wearable and portable electronic devices. Perovskite solar cells with a flexible fiber structure were now prepared for the first time by continuously winding an aligned multiwalled carbon nanotube sheet electrode onto a fiber electrode; photoactive perovskite materials were incorporated in between them through a solution process. The fiber-shaped perovskite solar cell exhibits an energy conversion efficiency of 3.3%, which remained stable on bending. The perovskite solar cell fibers may be woven into electronic textiles for large-scale application by well-developed textile technologies.

  16. Performance of planar heterojunction perovskite solar cells under light concentration

    Directory of Open Access Journals (Sweden)

    Aaesha Alnuaimi

    2016-11-01

    Full Text Available In this work, we present 2D simulation of planar heterojunction perovskite solar cells under high concentration using physics-based TCAD. The performance of planar perovskite heterojunction solar cells is examined up to 1000 suns. We analyze the effect of HTM mobility and band structure, surface recombination velocities at interfaces and the effect of series resistance under concentrated light. The simulation results revealed that the low mobility of HTM material limits the improvement in power conversation efficiency of perovskite solar cells under concentration. In addition, large band offset at perovskite/HTM interface contributes to the high series resistance. Moreover, losses due to high surface recombination at interfaces and the high series resistance deteriorate significantly the performance of perovskite solar cells under concentration.

  17. Two-photon pumped lead halide perovskite nanowire lasers

    CERN Document Server

    Gu, Zhiyuan; Sun, Wenzhao; Li, Jinakai; Liu, Shuai; Song, Qinghai; Xiao, Shumin

    2015-01-01

    Solution-processed lead halide perovskites have shown very bright future in both solar cells and microlasers. Very recently, the nonlinearity of perovskites started to attract considerable research attention. Second harmonic generation and two-photon absorption have been successfully demonstrated. However, the nonlinearity based perovskite devices such as micro- & nano- lasers are still absent. Here we demonstrate the two-photon pumped nanolasers from perovskite nanowires. The CH3NH3PbBr3 perovskite nanowires were synthesized with one-step solution self-assembly method and dispersed on glass substrate. Under the optical excitation at 800 nm, two-photon pumped lasing actions with periodic peaks have been successfully observed at around 546 nm. The obtained quality (Q) factors of two-photon pumped nanolasers are around 960, and the corresponding thresholds are about 674?J=cm2. Both the Q factors and thresholds are comparable to conventional whispering gallery modes in two-dimensional polygon microplates. Ou...

  18. Highly efficient light management for perovskite solar cells.

    Science.gov (United States)

    Wang, Dong-Lin; Cui, Hui-Juan; Hou, Guo-Jiao; Zhu, Zhen-Gang; Yan, Qing-Bo; Su, Gang

    2016-01-06

    Organic-inorganic halide perovskite solar cells have enormous potential to impact the existing photovoltaic industry. As realizing a higher conversion efficiency of the solar cell is still the most crucial task, a great number of schemes were proposed to minimize the carrier loss by optimizing the electrical properties of the perovskite solar cells. Here, we focus on another significant aspect that is to minimize the light loss by optimizing the light management to gain a high efficiency for perovskite solar cells. In our scheme, the slotted and inverted prism structured SiO2 layers are adopted to trap more light into the solar cells, and a better transparent conducting oxide layer is employed to reduce the parasitic absorption. For such an implementation, the efficiency and the serviceable angle of the perovskite solar cell can be promoted impressively. This proposal would shed new light on developing the high-performance perovskite solar cells.

  19. Recent progress and challenges of organometal halide perovskite solar cells

    Science.gov (United States)

    Yang, Liyan; Barrows, Alexander T.; Lidzey, David G.; Wang, Tao

    2016-02-01

    We review recent progress in the development of organometal halide perovskite solar cells. We discuss different compounds used to construct perovskite photoactive layers, as well as the optoelectronic properties of this system. The factors that affect the morphology of the perovskite active layer are explored, e.g. material composition, film deposition methods, casting solvent and various post-treatments. Different strategies are reviewed that have recently emerged to prepare high performing perovskite films, creating polycrystalline films having either large or small grain size. Devices that are constructed using meso-superstructured and planar architectures are summarized and the impact of the fabrication process on operational efficiency is discussed. Finally, important research challenges (hysteresis, thermal and moisture instability, mechanical flexibility, as well as the development of lead-free materials) in the development of perovskite solar cells are outlined and their potential solutions are discussed.

  20. Theory of hydrogen migration in organic-inorganic halide perovskites.

    Science.gov (United States)

    Egger, David A; Kronik, Leeor; Rappe, Andrew M

    2015-10-12

    Solar cells based on organic-inorganic halide perovskites have recently been proven to be remarkably efficient. However, they exhibit hysteresis in their current-voltage curves, and their stability in the presence of water is problematic. Both issues are possibly related to a diffusion of defects in the perovskite material. By using first-principles calculations based on density functional theory, we study the properties of an important defect in hybrid perovskites-interstitial hydrogen. We show that differently charged defects occupy different crystal sites, which may allow for ionization-enhanced defect migration following the Bourgoin-Corbett mechanism. Our analysis highlights the structural flexibility of organic-inorganic perovskites: successive iodide displacements, combined with hydrogen bonding, enable proton diffusion with low migration barriers. These findings indicate that hydrogen defects can be mobile and thus highly relevant for the performance of perovskite solar cells.

  1. Random lasing actions in self-assembled perovskite nanoparticles

    CERN Document Server

    Liu, Shuai; Li, Jiankai; Gu, Zhiyuan; Wang, Kaiyang; Xiao, Shumin; Song, Qinghai

    2015-01-01

    Solution-based perovskite nanoparticles have been intensively studied in past few years due to their applications in both photovoltaic and optoelectronic devices. Here, based on the common ground between the solution-based perovskite and random lasers, we have studied the mirrorless lasing actions in self-assembled perovskite nanoparticles. After the synthesis from solution, discrete lasing peaks have been observed from the optically pumped perovskites without any well-defined cavity boundaries. The obtained quality (Q) factors and thresholds of random lasers are around 500 and 60 uJ/cm2, respectively. Both values are comparable to the conventional perovskite microdisk lasers with polygon shaped cavity boundaries. From the corresponding studies on laser spectra and fluorescence microscope images, the lasing actions are considered as random lasers that are generated by strong multiple scattering in random gain media. In additional to conventional single-photon excitation, due to the strong nonlinear effects of...

  2. Self-Assembled PbSe Nanowire:Perovskite Hybrids

    KAUST Repository

    Yang, Zhenyu

    2015-12-02

    © 2015 American Chemical Society. Inorganic semiconductor nanowires are of interest in nano- and microscale photonic and electronic applications. Here we report the formation of PbSe nanowires based on directional quantum dot alignment and fusion regulated by hybrid organic-inorganic perovskite surface ligands. All material synthesis is carried out at mild temperatures. Passivation of PbSe quantum dots was achieved via a new perovskite ligand exchange. Subsequent in situ ammonium/amine substitution by butylamine enables quantum dots to be capped by butylammonium lead iodide, and this further drives the formation of a PbSe nanowire superlattice in a two-dimensional (2D) perovskite matrix. The average spacing between two adjacent nanowires agrees well with the thickness of single atomic layer of 2D perovskite, consistent with the formation of a new self-assembled semiconductor nanowire:perovskite heterocrystal hybrid.

  3. 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. [...

  4. 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.

  5. 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.

  6. 高铁酸盐溶液氧化直接耐晒黑G的效果及机理%Degradation and mechanism of direct fast black G with ferrate solution

    Institute of Scientific and Technical Information of China (English)

    张彦平; 许国仁

    2009-01-01

    研究了高铁酸盐溶液(FS)降解直接耐晒黑G(DB19)的效果,并采用UV-Vis、GC/MS等方法对降解机理进行了分析.结果表明,FS对DB19的脱色效果较好,pH<7.7时,5min的脱色率达到94%以上,最佳范围为pH<10.7.FS的最佳投加量为20mg/L,反应60min时,对DB19色度和COD的去除率分别为95%和60%.FS对DB19废水TOC的去除率为5%,表明染料大分子难以被完全矿化.UV-Vis扫描、GC/MS分析和体系pH值的变化结果表明,染料分子的偶氮键能被迅速攻击破坏,使染料消色,染料大分子被氧化为有机小分子中间产物,提高了染料废水的可生化性,同时产生大量的酸性有机中间物质,导致体系的pH值显著降低.%The degradation of direct fast black G (DB19) with ferrate solution (FS) was studied, and the mechanism was analyzed by UV-Vis and GC/MS methods. The decolorization ratio was above 94% after 5min in the presence of FS at pH<7.7, and the optimal range of pH was lower than 10.7. The decolorization ratio and COD removal ratio were 95% and 60% after 60min, respectively, in the case of FS which dosage was 20mg/L. TOC removal ratio of DB19 was only 5% when ferrate was supplied to reaction system, which indicated that it was difficult for FS to mineralize dye macromolecule. The results of UV-Vis, GC/MS and pH change showed that the azo bonds of dye molecule were attracted and cleaved, causing decolorization of DB19. The dye macromolecule could be oxidized to small molecule, which increased the biodegradability of the dye wastewater. Furthermore, a large number of acidic organic intermediates were detected, which obviously caused the decrease of pH.

  7. Deciphering Halogen Competition in Organometallic Halide Perovskite Growth.

    Science.gov (United States)

    Yang, Bin; Keum, Jong; Ovchinnikova, Olga S; Belianinov, Alex; Chen, Shiyou; Du, Mao-Hua; Ivanov, Ilia N; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2016-04-20

    Organometallic halide perovskites (OHPs) hold great promise for next-generation, low-cost optoelectronic devices. During the chemical synthesis and crystallization of OHP thin films, a major unresolved question is the competition between multiple halide species (e.g., I(-), Cl(-), Br(-)) in the formation of the mixed-halide perovskite crystals. Whether Cl(-) ions are successfully incorporated into the perovskite crystal structure or, alternatively, where they are located is not yet fully understood. Here, in situ X-ray diffraction measurements of crystallization dynamics are combined with ex situ TOF-SIMS chemical analysis to reveal that Br(-) or Cl(-) ions can promote crystal growth, yet reactive I(-) ions prevent them from incorporating into the lattice of the final perovskite crystal structure. The Cl(-) ions are located in the grain boundaries of the perovskite films. These findings significantly advance our understanding of the role of halogens during synthesis of hybrid perovskites and provide an insightful guidance to the engineering of high-quality perovskite films, essential for exploring superior-performing and cost-effective optoelectronic devices.

  8. A Review on Visible Light Active Perovskite-Based Photocatalysts

    Directory of Open Access Journals (Sweden)

    Pushkar Kanhere

    2014-12-01

    Full Text Available Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (λ > 400 nm active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3 structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development.

  9. Improving the photovoltaic performance of perovskite solar cells with acetate.

    Science.gov (United States)

    Zhao, Qian; Li, G R; Song, Jian; Zhao, Yulong; Qiang, Yinghuai; Gao, X P

    2016-12-09

    In an all-solid-state perovskite solar cell, methylammonium lead halide film is in charge of generating photo-excited electrons, thus its quality can directly influence the final photovoltaic performance of the solar cell. This paper accentuates a very simple chemical approach to improving the quality of a perovskite film with a suitable amount of acetic acid. With introduction of acetate ions, a homogeneous, continual and hole-free perovskite film comprised of high-crystallinity grains is obtained. UV-visible spectra, steady-state and time-resolved photoluminescence (PL) spectra reveal that the obtained perovskite film under the optimized conditions shows a higher light absorption, more efficient electron transport, and faster electron extraction to the adjoining electron transport layer. The features result in the optimized perovskite film can provide an improved short-circuit current. The corresponding solar cells with a planar configuration achieves an improved power conversion efficiency of 13.80%, and the highest power conversion efficiency in the photovoltaic measurements is up to 14.71%. The results not only provide a simple approach to optimizing perovskite films but also present a novel angle of view on fabricating high-performance perovskite solar cells.

  10. Impact of Interfacial Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Cho, An-Na; Park, Nam-Gyu

    2017-07-23

    Perovskite solar cell (PCSs) is composed of organic-inorganic lead halide perovskite as light harvester. Since the first report on long-term durable 9.7% efficient solid-state perovskite solar cell in 2012, organic-inorganic halide perovskite received great attention because of its superb opto-electronic properties. As a result, a power conversion efficiency (PCE) exceeding 22% was certified. Controlling grain size and grain boundary of perovskite layer perovskite is important for attaining high efficiency. In addition, interfacial engineering is equally or more important to improve further PCE via better charge collection and reduction in charge recombination. In this article, type of interfacial layers and their impacts on photovoltaic performance are investigated for the normal and inverted architectures. Grain boundary engineering is also included because it is related to interfacial engineering and grain boundary in perovskite layer plays important role in charge conduction, recombination and carrier life time. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Perovskite Materials for Light-Emitting Diodes and Lasers.

    Science.gov (United States)

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices.

  12. Low -Dimensional Halide Perovskites and Their Advanced Optoelectronic Applications

    Science.gov (United States)

    Zhang, Jian; Yang, Xiaokun; Deng, Hui; Qiao, Keke; Farooq, Umar; Ishaq, Muhammad; Yi, Fei; Liu, Huan; Tang, Jiang; Song, Haisheng

    2017-07-01

    Metal halide perovskites are crystalline materials originally developed out of scientific curiosity. They have shown great potential as active materials in optoelectronic applications. In the last 6 years, their certified photovoltaic efficiencies have reached 22.1%. Compared to bulk halide perovskites, low-dimensional ones exhibited novel physical properties. The photoluminescence quantum yields of perovskite quantum dots are close to 100%. The external quantum efficiencies and current efficiencies of perovskite quantum dot light-emitting diodes have reached 8% and 43 cd A-1, respectively, and their nanowire lasers show ultralow-threshold room-temperature lasing with emission tunability and ease of synthesis. Perovskite nanowire photodetectors reached a responsivity of 10 A W-1 and a specific normalized detectivity of the order of 1012 Jones. Different from most reported reviews focusing on photovoltaic applications, we summarize the rapid progress in the study of low-dimensional perovskite materials, as well as their promising applications in optoelectronic devices. In particular, we review the wide tunability of fabrication methods and the state-of-the-art research outputs of low-dimensional perovskite optoelectronic devices. Finally, the anticipated challenges and potential for this exciting research are proposed.

  13. Review of magnetocaloric effect in perovskite-type oxides

    Institute of Scientific and Technical Information of China (English)

    Zhong Wei; Au Chak-Tong; Du You-Wei

    2013-01-01

    We survey the magnetocaloric effect in perovskite-type oxides (including doped ABO3-type manganese oxides,A3B2O7-type two-layered perovskite oxides,and A2B'B''O6-type ordered double-perovskite oxides).Magnetic entropy changes larger than those of gadolinium can be observed in polycrystalline La(Ⅰ)-xCaxMnO3 and alkali-metal (Na or K)doped La0.8Ca0.2MnO3 perovskite-type manganese oxides.The large magnetic entropy change produced by an abrupt reduction of magnetization is attributed to the anomalous thermal expansion at the Curie temperature.Considerable magnetic entropy changes can also be observed in two-layered perovskites La1.6Ca1.4Mn2O7 and La2.5-xK0.5+xMn2O7+δ(0 < x < 0.5),and double-perovskite Ba2Fe1+xMo1-xO6(0 ≤ x ≤ 0.3) near their respective Curie temperatures.Compared with rare earth metals and their alloys,the perovskite-type oxides are lower in cost,and they exhibit higher chemical stability and higher electrical resistivity,which together favor lower eddy-current heating.They are potential magnetic refrigerants at high temperatures,especially near room temperature.

  14. Anion order in perovskites: a group-theoretical analysis.

    Science.gov (United States)

    Talanov, M V; Shirokov, V B; Talanov, V M

    2016-03-01

    Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting of BO6 octahedra, distortions caused by the cooperative Jahn-Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: the AX class (the simultaneous ordering of A cations and anions in cubic perovskite structure), the BX class (the simultaneous ordering of B cations and anions) and the X class (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are the AX and BX classes. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.

  15. Perovskite/Carbon Composites: Applications in Oxygen Electrocatalysis.

    Science.gov (United States)

    Zhu, Yinlong; Zhou, Wei; Shao, Zongping

    2017-03-01

    Oxygen electrocatalysis, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), plays an extremely important role in oxygen-based renewable-energy technologies such as rechargeable metal-air batteries, regenerative fuel cells and water splitting. Perovskite oxides have recently attracted increasing interest and hold great promise as efficient ORR and OER catalysts to replace noble-metal-based catalysts, owing to their high intrinsic catalytic activity, abundant variety, low cost, and rich resources. The introduction of perovskite-carbon interfaces by forming perovskite/carbon composites may bring a synergistic effect between the two phases, thus benefiting the oxygen electrocatalysis. This review provides a comprehensive overview of recent advances in perovskite/carbon composites for oxygen electrocatalysis in alkaline media, aiming to provide insights into the key parameters that influence the ORR/OER performance of the composites, including the physical/chemical properties and morphologies of the perovskites, the multiple roles of carbon, the synthetic method and the synergistic effect. A special emphasis is placed on the origin of the synergistic effect associated with the interfacial interaction between the perovskite and the carbon phases for enhanced ORR/OER performance. Finally, the existing challenges and the future directions for the synthesis and development of more efficient oxygen catalysts based on perovskite/carbon composites are proposed.

  16. Improving the photovoltaic performance of perovskite solar cells with acetate

    Science.gov (United States)

    Zhao, Qian; Li, G. R.; Song, Jian; Zhao, Yulong; Qiang, Yinghuai; Gao, X. P.

    2016-12-01

    In an all-solid-state perovskite solar cell, methylammonium lead halide film is in charge of generating photo-excited electrons, thus its quality can directly influence the final photovoltaic performance of the solar cell. This paper accentuates a very simple chemical approach to improving the quality of a perovskite film with a suitable amount of acetic acid. With introduction of acetate ions, a homogeneous, continual and hole-free perovskite film comprised of high-crystallinity grains is obtained. UV-visible spectra, steady-state and time-resolved photoluminescence (PL) spectra reveal that the obtained perovskite film under the optimized conditions shows a higher light absorption, more efficient electron transport, and faster electron extraction to the adjoining electron transport layer. The features result in the optimized perovskite film can provide an improved short-circuit current. The corresponding solar cells with a planar configuration achieves an improved power conversion efficiency of 13.80%, and the highest power conversion efficiency in the photovoltaic measurements is up to 14.71%. The results not only provide a simple approach to optimizing perovskite films but also present a novel angle of view on fabricating high-performance perovskite solar cells.

  17. Modeling of optical losses in perovskite solar cells

    Science.gov (United States)

    Taghavi, M. Javad; Houshmand, Mohammad; Zandi, M. Hossein; Gorji, Nima E.

    2016-09-01

    The optical losses within the structure of hybrid perovskite solar cells are investigated using only the optical properties of each layer e.g. refractive index and extinction coefficient. This model allows calculating the transmission/reflection rates at the interfaces and absorption loss within any layer. Then, the short circuit current density and loss percentage are calculated versus the perovskite and TiO2 thicknesses from 50 nm to 150 nm. To make our calculations closer to reality, we extracted the optical properties of each device component from the literature reports on glass/TCO/TiO2/perovskite/metal. The simulations were fitted with the experimental results of some relevant references. Our simulations show that ITO transmits the light better than SnO2 as the TCO front electrode, and the light reflection at both sides of the perovskite layer, e.g. at TiO2/perovskite and perovskite/Spiro-OMeTAD, is lower than 25%. The light interference and multiple reflections have been accounted in our calculations and finally we showed that a thicker TiO2 and perovskite cause more optical loss in current density due to stronger absorption.

  18. Properties of perovskites and other oxides

    CERN Document Server

    Müller, K Alex

    2010-01-01

    In this book some 50 papers published by K A Muller as author or co-author over several decades, amplified by more recent work mainly by T W Kool with collaborators, are reproduced. The main subject is Electron Paramagnetic Resonance (EPR) applied to the study of perovskites and other oxides with related subjects. This wealth of papers is organized into eleven chapters, each with an introductory text written in the light of current understanding. The contributions of the first author on structural phase transitions have been immense, and because K A Muller and J C Fayet have published a review

  19. Competing structural instabilities in cubic perovskites

    CERN Document Server

    Vanderbilt, D

    1994-01-01

    We study the antiferrodistortive instability and its interaction with ferroelectricity in cubic perovskite compounds. Our first-principles calculations show that coexistence of both instabilities is very common. We develop a first-principles scheme to study the thermodynamics of these compounds when both instabilities are present, and apply it to SrTiO$_3$. We find that increased pressure enhances the antiferrodistortive instability while suppressing the ferroelectric one. Moreover, the presence of one instability tends to suppress the other. A very rich $P$--$T$ phase diagram results.

  20. Elasticity of AlFeO(3) and FeAlO(3) perovskite and post-perovskite from first-principles calculations

    OpenAIRE

    Caracas, Razvan

    2010-01-01

    International audience; We use state-of-the-art ab initio calculations based on the generalized gradient approximation of the density functional theory in the planar augmented wavefunction formalism to determine the elastic constants tensor of perovskite and post-perovskite with formulas AlFeO(3) and FeAlO(3) in which Fe or Al respectively occupy only octahedral sites, for the stable magnetic configurations. The phase transition between perovskite and post-perovskite is associated with a site...

  1. Halide-Dependent Electronic Structure of Organolead Perovskite Materials

    KAUST Repository

    Buin, Andrei

    2015-06-23

    © 2015 American Chemical Society. Organometal halide perovskites have recently attracted tremendous attention both at the experimental and theoretical levels. These materials, in particular methylammonium triiodide, are still limited by poor chemical and structural stability under ambient conditions. Today this represents one of the major challenges for polycrystalline perovskite-based photovoltaic technology. In addition to this, the performance of perovskite-based devices is degraded by deep localized states, or traps. To achieve better-performing devices, it is necessary to understand the nature of these states and the mechanisms that lead to their formation. Here we show that the major sources of deep traps in the different halide systems have different origin and character. Halide vacancies are shallow donors in I-based perovskites, whereas they evolve into a major source of traps in Cl-based perovskites. Lead interstitials, which can form lead dimers, are the dominant source of defects in Br-based perovskites, in line with recent experimental data. As a result, the optimal growth conditions are also different for the distinct halide perovskites: growth should be halide-rich for Br and Cl, and halide-poor for I-based perovskites. We discuss stability in relation to the reaction enthalpies of mixtures of bulk precursors with respect to final perovskite product. Methylammonium lead triiodide is characterized by the lowest reaction enthalpy, explaining its low stability. At the opposite end, the highest stability was found for the methylammonium lead trichloride, also consistent with our experimental findings which show no observable structural variations over an extended period of time.

  2. Theoretical calculations on layered perovskites: implications for photocatalysis

    Directory of Open Access Journals (Sweden)

    Xiang Liu

    2014-12-01

    Full Text Available The application of first-principles calculations to the study of layered perovskites is reviewed here, with an emphasis on properties relevant to the use of these materials in photocatalysis. First, the accuracies of the theoretical methods in common use for the study of layered perovskites are compared. The main body of the article then reviews studies of the bulk atomic and electronic structures of pure and doped perovskites; first-principles thermodynamics studies; studies of surfaces and studies of adsorption on surfaces.

  3. NREL Studies Carrier Separation and Transport in Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    2016-01-01

    NREL scientists studied charge separation and transport in perovskite solar cells by determining the junction structure across the solar device using the nanoelectrical characterization technique of Kelvin probe force microscopy. The distribution of electrical potential across both planar and porous devices demonstrates a p-n junction structure at the interface between titanium dioxide and perovskite. In addition, minority-carrier transport within the devices operates under diffusion/drift. Clarifying the fundamental junction structure provides significant guidance for future research and development. This NREL study points to the fact that improving carrier mobility is a critical factor for continued efficiency gains in perovskite solar cells.

  4. UV Degradation and Recovery of Perovskite Solar Cells

    Science.gov (United States)

    Lee, Sang-Won; Kim, Seongtak; Bae, Soohyun; Cho, Kyungjin; Chung, Taewon; Mundt, Laura E.; Lee, Seunghun; Park, Sungeun; Park, Hyomin; Schubert, Martin C.; Glunz, Stefan W.; Ko, Yohan; Jun, Yongseok; Kang, Yoonmook; Lee, Hae-Seok; Kim, Donghwan

    2016-01-01

    Although the power conversion efficiency of perovskite solar cells has increased from 3.81% to 22.1% in just 7 years, they still suffer from stability issues, as they degrade upon exposure to moisture, UV light, heat, and bias voltage. We herein examined the degradation of perovskite solar cells in the presence of UV light alone. The cells were exposed to 365 nm UV light for over 1,000 h under inert gas at perovskite material. PMID:27909338

  5. An efficient copper phthalocyanine additive of perovskite precursor for improving the photovoltaic performance of planar perovskite solar cells

    Science.gov (United States)

    Wu, Shufang; Liu, Qingwei; Zheng, Ya; Li, Renjie; Peng, Tianyou

    2017-08-01

    Solution processable planar heterojunction perovskite solar cell has drawn much attention as a promising low-cost photovoltaic device, and much effort has been made to improve its power conversion efficiency by choosing appropriate additives for the perovskite precursor solution. Different to those additives reported, a soluble and thermal stable tert-butyl substituted copper phthalocyanine (CuPc(tBu)4) as additive is first introduced into the perovskite precursor solution of a planar perovskite solar cell that is fabricated via the one-step solution process. It is found that the pristine device without CuPc(tBu)4 additive exhibits a power conversion efficiency of 15.3%, while an extremely low concentration (4.4 × 10-3 mM) of CuPc(tBu)4 in the precursor solution leads to the corresponding device achieving an enhanced power conversion efficiency of 17.3%. CuPc(tBu)4 as an additive can improve the quality of perovskite layer with higher crystallinity and surface coverage, then resulting in enhanced light absorption and reduced charge recombination, and thus the better power conversion efficiency. The finding presented here provides a new choice for improving the quality of perovskite layer and the photovoltaic performance of the planar heterojunction perovskite solar cells.

  6. A novel rapid synthesis of Fe{sub 2}O{sub 3}/graphene nanocomposite using ferrate(VI) and its application as a new kind of nanocomposite modified electrode as electrochemical sensor

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, Mohammad Ali, E-mail: ma_karimi43@yahoo.com [Department of Chemistry, Payame Noor University, 19395-4697 Tehran (Iran, Islamic Republic of); Department of Chemistry & Nanoscience and Nanotechnology Research Laboratory (NNRL), Payame Noor University, Sirjan (Iran, Islamic Republic of); Banifatemeh, Fatemeh [Department of Chemistry, Payame Noor University, 19395-4697 Tehran (Iran, Islamic Republic of); Department of Chemistry, Payame Noor University, Mashhad (Iran, Islamic Republic of); Hatefi-Mehrjardi, Abdolhamid [Department of Chemistry, Payame Noor University, 19395-4697 Tehran (Iran, Islamic Republic of); Department of Chemistry & Nanoscience and Nanotechnology Research Laboratory (NNRL), Payame Noor University, Sirjan (Iran, Islamic Republic of); Tavallali, Hossein [Department of Chemistry, Payame Noor University, 19395-4697 Tehran (Iran, Islamic Republic of); Department of Chemistry, Payame Noor University, Shiraz (Iran, Islamic Republic of); Eshaghia, Zarrin [Department of Chemistry, Payame Noor University, Mashhad (Iran, Islamic Republic of); Deilamy-Rad, Gohar [Department of Chemistry, Payame Noor University, Shiraz (Iran, Islamic Republic of)

    2015-10-15

    Highlights: • A novel rapid synthesis of rGO–Fe{sub 2}O{sub 3} nanocomposite was developed using Fe(VI). • Fe(VI) as an environmentally friendly oxidant was introduced for GO synthesis. • Synthesized rGO–Fe{sub 2}O{sub 3} nanocomposite was applied as electrochemical sensor. • A non-enzymatic sensor was developed for H{sub 2}O{sub 2}. - Abstract: In this study, a novel, simple and sensitive non-enzymatic hydrogen peroxide electrochemical sensor was developed using reduced graphene oxide/Fe{sub 2}O{sub 3} nanocomposite modified glassy carbon electrode. This nanocomposite was synthesized by reaction of sodium ferrate with graphene in alkaline media. This reaction completed in 5 min and the products were stable and its deposition on the surface of electrode is investigated. It has been found the apparent charge transfer rate constant (ks) is 0.52 and transfer coefficient (α) is 0.61 for electron transfer between the modifier and glassy carbon electrode. Electrochemical behavior of this electrode and its ability to catalyze the electro-reduction of H{sub 2}O{sub 2} has been studied by cyclic voltammetry and chronoamperometry at different experimental conditions. The analytical parameters showed the good ability of electrode as a sensor for H{sub 2}O{sub 2} amperometric reduction.

  7. 新型水处理剂高铁酸钾的制备及应用研究%Progress of Preparation and Application of Potassium Ferrate in Water Treatment

    Institute of Scientific and Technical Information of China (English)

    李元昊; 丁忠浩

    2011-01-01

    Potassium ferrate is a efficient multipurpose water treatment agent with the novel properties of the oxidation, oxidation, adsorption, flocculation, coagulation, disinfection, and deodorization. This paper describes the preparation, features of potassium ferrateand, and the application in water treatment,its reaction mechanism was also discussed. Also, the suggestions and prospects are proposed for study on the practial and hyphenated techniques.%指出了高铁酸钾是一种集氧化、吸附、絮凝、助凝、杀菌、除臭为一体的新型高效多功能水处理剂,阐述了高铁酸钾的制备、特性以及在污水处理中的应用特点,对其反应机理进行了探讨,展望了研究其高效、低耗、联用技术的十分广阔的开发前景。

  8. 三草酸合铁(Ⅲ)酸钾合成条件的改进与探索%Conditions of the Formation for Potassium tris(oxalato)ferrate(III) trihydrate: Improvement and Exploration

    Institute of Scientific and Technical Information of China (English)

    雷克林

    2012-01-01

    Aiming at the previous problems, it tries to optimize conditions of the formation for Potassium tris(oxalato)ferrate(lll) trihydrate. The experimental results show that, FeC2O4 washed with hot water, when the water tempreture is 40℃, H2O2 is added into the water drop by drop, then it must be boiled for 30s. After consentration, it is crystalized and bigger viridis crystals are gotten. Meanwhile, repeatability of experimental result is improved, productivity and purity of the products are enhanced.%针对无机化学综合实验三草酸合铁(Ⅲ)酸钾合成过程中存在的问题,对[K3Fe(C2O4)3].3H2O的合成条件进行探索和优化.实验结果表明:在用热水(40℃)洗涤FeC2O4,40℃时逐滴加入H2O2后煮沸30s,利用浓缩后挂棉线的方式进行结晶等条件下,得到粒度较大的翠绿色晶体,可改善实验结果的重现性、提高产品的产率和纯度.

  9. Perovskite oxides: Oxygen electrocatalysis and bulk structure

    Science.gov (United States)

    Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, Ernest

    1987-01-01

    Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

  10. Neutral Color Semitransparent Microstructured Perovskite Solar Cells

    KAUST Repository

    Eperon, Giles E.

    2014-01-28

    Neutral-colored semitransparent solar cells are commercially desired to integrate solar cells into the windows and cladding of buildings and automotive applications. Here, we report the use of morphological control of perovskite thin films to form semitransparent planar heterojunction solar cells with neutral color and comparatively high efficiencies. We take advantage of spontaneous dewetting to create microstructured arrays of perovskite "islands", on a length-scale small enough to appear continuous to the eye yet large enough to enable unattenuated transmission of light between the islands. The islands are thick enough to absorb most visible light, and the combination of completely absorbing and completely transparent regions results in neutral transmission of light. Using these films, we fabricate thin-film solar cells with respectable power conversion efficiencies. Remarkably, we find that such discontinuous films still have good rectification behavior and relatively high open-circuit voltages due to the inherent rectification between the n- and p-type charge collection layers. Furthermore, we demonstrate the ease of "color-tinting" such microstructured perovksite solar cells with no reduction in performance, by incorporation of a dye within the hole transport medium. © 2013 American Chemical Society.

  11. Finding New Perovskite Halides via Machine learning

    Directory of Open Access Journals (Sweden)

    Ghanshyam ePilania

    2016-04-01

    Full Text Available Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning via building a support vector machine (SVM based classifier that uses elemental features (or descriptors to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  12. Perspectives on organolead halide perovskite photovoltaics

    Science.gov (United States)

    Hariz, Alex

    2016-07-01

    A number of photovoltaic technologies have been developed for large-scale solar-power production. The single-crystal first-generation photovoltaic devices were followed by thin-film semiconductor absorber layers layered between two charge-selective contacts, and more recently, by nanostructured or mesostructured solar cells that utilize a distributed heterojunction to generate charge carriers and to transport holes and electrons in spatially separated conduits. Even though a number of materials have been trialed in nanostructured devices, the aim of achieving high-efficiency thin-film solar cells in such a manner as to rival the silicon technology has yet to be attained. Organolead halide perovskites have recently emerged as a promising material for high-efficiency nanoinfiltrated devices. An examination of the efficiency evolution curve reveals that interfaces play a paramount role in emerging organic electronic applications. To optimize and control the performance in these devices, a comprehensive understanding of the contacts is essential. However, despite the apparent advances made, a fundamental theoretical analysis of the physical processes taking place at the contacts is still lacking. However, experimental ideas, such as the use of interlayer films, are forging marked improvements in efficiencies of perovskite-based solar cells. Furthermore, issues of long-term stability and large-area manufacturing have some way to go before full commercialization is possible.

  13. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  14. Magnetic and Electric Properties of , ( Layered Perovskites

    Directory of Open Access Journals (Sweden)

    A. I. Ali

    2013-01-01

    Full Text Available The electric and magnetic properties of layered perovskites have been investigated systematically over the doping range . It was found that both Sr1.5Y0.5CoO4 and Sr1.4Y0.6CoO4 undergo ferromagnetic (FM transition around 145 K and 120 K, respectively. On the other hand, Sr1.3Y0.7CoO4 and Sr1.2Y0.8CoO4 compounds showed paramagnetic behavior over a wide range of temperatures. In addition, spin-glass transition ( was observed at 10 K for Sr1.3Y0.7CoO4. All investigated samples are semiconducting-like within the temperature range of 10–300 K. The temperature dependence of the electrical resistivity, , was described by two-dimensional variable range hopping (2D-VRH model at 50 K < ≤ 300 K. Comparison with other layered perovskites was discussed in this work.

  15. Finding New Perovskite Halides via Machine learning

    Science.gov (United States)

    Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho; Lookman, Turab

    2016-04-01

    Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning) via building a support vector machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

  16. Perovskite Solar Cells: High Efficiency Pb-In Binary Metal Perovskite Solar Cells (Adv. Mater. 31/2016).

    Science.gov (United States)

    Wang, Zhao-Kui; Li, Meng; Yang, Ying-Guo; Hu, Yun; Ma, Heng; Gao, Xing-Yu; Liao, Liang-Sheng

    2016-08-01

    On page 6695, X. Y. Gao, L.-S. Liao, and co-workers describe the fabrication of mixed Pb-In perovskite solar cells, using indium (III) chloride and lead (II) chloride with methylammonium iodide. A maximum power conversion efficiency as high as 17.55% is achieved owing to the high quality of the perovskites with multiple ordered crystal orientations. This work demonstrates the possibility of substituting the Pb (II) by using In (III), which opens a broad route to fabricating alloy perovskite solar cells with mitigated ecological impact. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Synthesis of hybrid organic-inorganic perovskite platelets by vacuum impregnation

    Science.gov (United States)

    Manthina, Venkata; Agrios, Alexander G.

    2016-11-01

    In perovskite solar cells and optoelectronics, perovskite film morphology controls the performance of the device. Various methods have been developed to control the morphology and coverage of the perovskite films. In this article platelet type perovskite morphlogy was synthesized using low temperature vacuum impregnation of the perovskite solution CH3NH3PbI3 resulting in complete coverage on TiO2 film. Vacuum impregnation synthesis of perovskites has the advantage of low cost and low temperature which faciliates application in flexible electronics and solar cells.

  18. Rain on Methylammonium Lead Iodide Based Perovskites: Possible Environmental Effects of Perovskite Solar Cells.

    Science.gov (United States)

    Hailegnaw, Bekele; Kirmayer, Saar; Edri, Eran; Hodes, Gary; Cahen, David

    2015-05-07

    The great promise of hybrid organic-inorganic lead halide perovskite (HOIP)-based solar cells is being challenged by its Pb content and its sensitivity to water. Here, the impact of rain on methylammonium lead iodide perovskite films was investigated by exposing such films to water of varying pH values, simulating exposure of the films to rain. The amount of Pb loss was determined using both gravimetric and inductively coupled plasma mass spectrometry measurements. Using our results, the extent of Pb loss to the environment, in the case of catastrophic module failure, was evaluated. Although very dependent on module siting, even total destruction of a large solar electrical power generating plant, based on HOIPs, while obviously highly undesirable, is estimated to be far from catastrophic for the environment.

  19. All-inorganic inverse perovskite solar cells using zinc oxide nanocolloids on spin coated perovskite layer.

    Science.gov (United States)

    Shibayama, Naoyuki; Kanda, Hiroyuki; Yusa, Shin-Ichi; Fukumoto, Shota; Baranwal, Ajay K; Segawa, Hiroshi; Miyasaka, Tsutomu; Ito, Seigo

    2017-01-01

    We confirmed the influence of ZnO nanoparticle size and residual water on performance of all inorganic perovskite solar cells. By decreasing the size of the ZnO nanoparticles, the short-circuit current density (Jsc) and open circuit photovoltage (Voc) values are increased and the conversion efficiency is improved. Although the Voc value is not affected by the influence of residual water in the solution for preparing the ZnO layer, the Jsc value drops greatly. As a result, it was found that it is important to use the oxide nanoparticles with a small particle diameter and to reduce the water content in the oxide forming material in order to manufacture a highly efficient all inorganic perovskite solar cells.

  20. All-inorganic inverse perovskite solar cells using zinc oxide nanocolloids on spin coated perovskite layer

    Science.gov (United States)

    Shibayama, Naoyuki; Kanda, Hiroyuki; Yusa, Shin-ichi; Fukumoto, Shota; Baranwal, Ajay K.; Segawa, Hiroshi; Miyasaka, Tsutomu; Ito, Seigo

    2017-07-01

    We confirmed the influence of ZnO nanoparticle size and residual water on performance of all inorganic perovskite solar cells. By decreasing the size of the ZnO nanoparticles, the short-circuit current density ( Jsc) and open circuit photovoltage ( Voc) values are increased and the conversion efficiency is improved. Although the Voc value is not affected by the influence of residual water in the solution for preparing the ZnO layer, the Jsc value drops greatly. As a result, it was found that it is important to use the oxide nanoparticles with a small particle diameter and to reduce the water content in the oxide forming material in order to manufacture a highly efficient all inorganic perovskite solar cells.

  1. 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.)

  2. Photovoltaics. Interface engineering of highly efficient perovskite solar cells.

    Science.gov (United States)

    Zhou, Huanping; Chen, Qi; Li, Gang; Luo, Song; Song, Tze-bing; Duan, Hsin-Sheng; Hong, Ziruo; You, Jingbi; Liu, Yongsheng; Yang, Yang

    2014-08-01

    Advancing perovskite solar cell technologies toward their theoretical power conversion efficiency (PCE) requires delicate control over the carrier dynamics throughout the entire device. By controlling the formation of the perovskite layer and careful choices of other materials, we suppressed carrier recombination in the absorber, facilitated carrier injection into the carrier transport layers, and maintained good carrier extraction at the electrodes. When measured via reverse bias scan, cell PCE is typically boosted to 16.6% on average, with the highest efficiency of ~19.3% in a planar geometry without antireflective coating. The fabrication of our perovskite solar cells was conducted in air and from solution at low temperatures, which should simplify manufacturing of large-area perovskite devices that are inexpensive and perform at high levels.

  3. Recent progress in efficient hybrid lead halide perovskite solar cells

    Science.gov (United States)

    Cui, Jin; Yuan, Huailiang; Li, Junpeng; Xu, Xiaobao; Shen, Yan; Lin, Hong; Wang, Mingkui

    2015-01-01

    The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices. PMID:27877815

  4. Ionic transport in hybrid lead iodide perovskite solar cells

    National Research Council Canada - National Science Library

    Eames, Christopher; Frost, Jarvist M; Barnes, Piers R F; O'Regan, Brian C; Walsh, Aron; Islam, M Saiful

    2015-01-01

    Solar cells based on organic-inorganic halide perovskites have recently shown rapidly rising power conversion efficiencies, but exhibit unusual behaviour such as current-voltage hysteresis and a low...

  5. Trapped charge-driven degradation of perovskite solar cells

    Science.gov (United States)

    Ahn, Namyoung; Kwak, Kwisung; Jang, Min Seok; Yoon, Heetae; Lee, Byung Yang; Lee, Jong-Kwon; Pikhitsa, Peter V.; Byun, Junseop; Choi, Mansoo

    2016-01-01

    Perovskite solar cells have shown unprecedent performance increase up to 22% efficiency. However, their photovoltaic performance has shown fast deterioration under light illumination in the presence of humid air even with encapulation. The stability of perovskite materials has been unsolved and its mechanism has been elusive. Here we uncover a mechanism for irreversible degradation of perovskite materials in which trapped charges, regardless of the polarity, play a decisive role. An experimental setup using different polarity ions revealed that the moisture-induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. We also identified the synergetic effect of oxygen on the process of moisture-induced degradation. The deprotonation of organic cations by trapped charge-induced local electric field would be attributed to the initiation of irreversible decomposition. PMID:27830709

  6. Recent progress in efficient hybrid lead halide perovskite solar cells.

    Science.gov (United States)

    Cui, Jin; Yuan, Huailiang; Li, Junpeng; Xu, Xiaobao; Shen, Yan; Lin, Hong; Wang, Mingkui

    2015-06-01

    The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices.

  7. Hydrogen Bonding and Stability of Hybrid Organic-Inorganic Perovskites

    KAUST Repository

    El-Mellouhi, Fedwa

    2016-09-08

    In the past few years, the efficiency of solar cells based on hybrid organic–inorganic perovskites has exceeded the level needed for commercialization. However, existing perovskites solar cells (PSCs) suffer from several intrinsic instabilities, which prevent them from reaching industrial maturity, and stabilizing PSCs has become a critically important problem. Here we propose to stabilize PSCs chemically by strengthening the interactions between the organic cation and inorganic anion of the perovskite framework. In particular, we show that replacing the methylammonium cation with alternative protonated cations allows an increase in the stability of the perovskite by forming strong hydrogen bonds with the halide anions. This interaction also provides opportunities for tuning the electronic states near the bandgap. These mechanisms should have a universal character in different hybrid organic–inorganic framework materials that are widely used.

  8. Double Charged Surface Layers in Lead Halide Perovskite Crystals

    KAUST Repository

    Sarmah, Smritakshi P.

    2017-02-01

    Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

  9. 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.

  10. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    Science.gov (United States)

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  11. Oxygen sensitivity of perovskite-type dielectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hara, Toru [Corporate Technology Planning Department, Research and Development Laboratory, Taiyo Yuden Co., Ltd., 8-1 Sakae-cho, Takasaki, Gunma 370-8522 (Japan)], E-mail: t-hara@jty.yuden.co.jp; Ishiguro, Takashi [Corporate Technology Planning Department, Research and Development Laboratory, Taiyo Yuden Co., Ltd., 8-1 Sakae-cho, Takasaki, Gunma 370-8522 (Japan); Wakiya, Naoki [Department of Materials Science, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu City, Shizuoka 432-8561 (Japan); Shinozaki, Kazuo [Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8550 (Japan)

    2009-04-15

    We have considered perovskite-type dielectric materials as promising candidates for use as highly sensitive oxygen sensors because of the indispensable interaction between ionic polarization in perovskites and adsorbed oxygen on the perovskite surface. In this study, a gas calibration system equipped with a ZrO{sub 2}-based oxygen pump (SIOC-200C, STLAB, Japan) was used. Among the materials studied, Cr:SrTiO{sub 3} shows sufficient sensitivity to detect residual oxygen in helium ambient at ppb levels. In contrast to Cr:SrTiO{sub 3}, Cr:BaTiO{sub 3} shows no oxygen sensitivity. The merits of Cr:SrTiO{sub 3} might be attributed to the coexistence of large and small polarons. Perovskite-based sensor is expected to provide a solution for real-time monitoring of residual oxygen during semiconductor manufacturing.

  12. Hole-Transport Materials for Perovskite Solar Cells.

    Science.gov (United States)

    Calió, Laura; Kazim, Samrana; Grätzel, Michael; Ahmad, Shahzada

    2016-11-14

    The pressure to move towards renewable energy has inspired researchers to look for ideas in photovoltaics that may lead to a major breakthrough. Recently the use of perovskites as a light harvester has lead to stunning progress. The power conversion efficiency of perovskite solar cells is now approaching parity (>22 %) with that of the established technology which took decades to reach this level of performance. The use of a hole transport material (HTM) remains indispensable in perovskite solar cells. Perovskites can conduct holes, but they are present at low levels, and for efficient charge extraction a HTM layer is a prerequisite. Herein we provide an overview of the diverse types of HTM available, from organic to inorganic, in the hope of encouraging further research and the optimization of these materials.

  13. Magnetism in Re-based ferrimagnetic double perovskites

    Science.gov (United States)

    Winkler, A.; Narayanan, N.; Mikhailova, D.; Bramnik, K. G.; Ehrenberg, H.; Fuess, H.; Vaitheeswaran, G.; Kanchana, V.; Wilhelm, F.; Rogalev, A.; Kolchinskaya, A.; Alff, L.

    2009-07-01

    We have investigated spin and orbital magnetic moments of the Re 5d ion in the double perovskites A2FeReO6 (A=Ba, Sr, Ca) by x-ray magnetic circular dichroism (XMCD) at the Re L2, 3 edges. In these ferrimagnetic compounds, an unusually large negative spin and positive orbital magnetic moment at the Re atoms was detected. The presence of a finite spin magnetic moment in a 'non-magnetic' double perovskite as observed in the double perovskite Sr2ScReO6 proves that Re has also a small, but finite intrinsic magnetic moment. We further show for the examples of Ba and Ca that the usually neglected alkaline earth ions undoubtedly also contribute to the magnetism in the ferrimagnetic double perovskites.

  14. Magnetism in Re-based ferrimagnetic double perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, A; Narayanan, N; Mikhailova, D; Bramnik, K G; Ehrenberg, H; Fuess, H; Kolchinskaya, A; Alff, L [Technische Universitaet Darmstadt, Petersenstrasse 23, 64287 Darmstadt (Germany); Vaitheeswaran, G; Kanchana, V [Royal Institute of Technology (KTH), Brinellvaegen 23, 10044 Stockholm (Sweden); Wilhelm, F; Rogalev, A [European Synchrotron Radiation Facility (ESRF), 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9 (France)], E-mail: alff@oxide.tu-darmstadt.de

    2009-07-15

    We have investigated spin and orbital magnetic moments of the Re 5d ion in the double perovskites A{sub 2}FeReO{sub 6} (A=Ba, Sr, Ca) by x-ray magnetic circular dichroism (XMCD) at the Re L{sub 2,3} edges. In these ferrimagnetic compounds, an unusually large negative spin and positive orbital magnetic moment at the Re atoms was detected. The presence of a finite spin magnetic moment in a 'non-magnetic' double perovskite as observed in the double perovskite Sr{sub 2}ScReO{sub 6} proves that Re has also a small, but finite intrinsic magnetic moment. We further show for the examples of Ba and Ca that the usually neglected alkaline earth ions undoubtedly also contribute to the magnetism in the ferrimagnetic double perovskites.

  15. Trapped charge-driven degradation of perovskite solar cells

    Science.gov (United States)

    Ahn, Namyoung; Kwak, Kwisung; Jang, Min Seok; Yoon, Heetae; Lee, Byung Yang; Lee, Jong-Kwon; Pikhitsa, Peter V.; Byun, Junseop; Choi, Mansoo

    2016-11-01

    Perovskite solar cells have shown unprecedent performance increase up to 22% efficiency. However, their photovoltaic performance has shown fast deterioration under light illumination in the presence of humid air even with encapulation. The stability of perovskite materials has been unsolved and its mechanism has been elusive. Here we uncover a mechanism for irreversible degradation of perovskite materials in which trapped charges, regardless of the polarity, play a decisive role. An experimental setup using different polarity ions revealed that the moisture-induced irreversible dissociation of perovskite materials is triggered by charges trapped along grain boundaries. We also identified the synergetic effect of oxygen on the process of moisture-induced degradation. The deprotonation of organic cations by trapped charge-induced local electric field would be attributed to the initiation of irreversible decomposition.

  16. Perovskite solar cells: On top of commercial photovoltaics

    Science.gov (United States)

    Albrecht, Steve; Rech, Bernd

    2017-01-01

    The efficiency of single-junction solar cells is intrinsically limited and high efficiency multi-junctions are not cost effective yet. Now, semi-transparent perovskite solar cells suggest that low cost multi-junctions could be within reach.

  17. Radiative efficiency of lead iodide based perovskite solar cells

    Science.gov (United States)

    Tvingstedt, Kristofer; Malinkiewicz, Olga; Baumann, Andreas; Deibel, Carsten; Snaith, Henry J.; Dyakonov, Vladimir; Bolink, Henk J.

    2014-08-01

    The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate.

  18. Numerical modeling of perovskite solar cells with a planar structure

    Science.gov (United States)

    Malyukov, S. P.; Sayenko, A. V.; Ivanova, A. V.

    2016-10-01

    The paper is devoted to the research and development of high-efficiency solar cells with a planar perovskite n-i-p structure. A numerical model of this solar cell in the drift- diffusion approximation based on Poisson equation and continuity equations provided to determine their photoelectric characteristics and design optimization. The author considers the spectral photogeneration, bulk and surface recombination, transport charge carriers in perovskite and their collection by the electron and hole transport layers. As a result of the simulation, it was obtained efficiency dependence on perovskite absorber material thickness and lifetime (diffusion length) of the charge carriers. It is found that in addition to absorption coefficient optimal perovskite thickness is determined largely by the charge carrier diffusion length, and it has the upper limit in thickness of 500-600 nm.

  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...... 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...

  20. Mesoporous PbI2 assisted growth of large perovskite grains for efficient perovskite solar cells based on ZnO nanorods

    Science.gov (United States)

    Li, Shibin; Zhang, Peng; Chen, Hao; Wang, Yafei; Liu, Detao; Wu, Jiang; Sarvari, Hojjatollah; Chen, Zhi David

    2017-02-01

    Perovskite solar cells (PSCs) have attracted great attention due to their low cost and high power conversion efficiency (PCE). However, the defects and grain boundaries in perovskite films dramatically degrade their performance. Here, we show a two-step annealing method to produce mesoporous PbI2 films for growth of continuous, pinhole-free perovskite films with large grains, followed by additional ethanol vapor annealing of perovskite films to reduce the defects and grain boundaries. The large perovskite grains dramatically suppress the carrier recombination, and consequently we obtain ZnO-nanorod-based PSCs that exhibit the best efficiency of 17.3%, with high reproducibility.

  1. Removing Oscillatoria and Humic Acid from Mixed Water by Potassium Ferrate(Ⅵ) Pre-oxidation and Co-coagulation%K2FeO4预氧化复合絮凝处理颤藻和腐殖酸混合水

    Institute of Scientific and Technical Information of China (English)

    赵春禄; 刘琰

    2011-01-01

    采用K2FeO4预氧化复合高岭土和聚合氯化铝(PAC)混凝处理了含颤藻和腐殖酸的混合水,并探讨了对处理后水中残留铝含量及其形态分布的影响.结果表明:投加4.0 mg·L-1K2FeO4预氧化就能使混合水样的浊度、腐殖酸和藻类的去除率分别达到94.05%、91.67%和90.78%,明显优于相同条件下单纯的PAC处理效果;水样的pH值对K2FeO4预氧化有显著的影响,在pH=6.5时效果最好;K2FeO4预氧化影响处理后水中残留铝的含量和形态,在最佳条件下总铝浓度降低了51.8%,特别是对人体毒害作用最大的溶解态铝降低了43.9%.%The mixed water containing Oscillatoria and humic acid was disposed by using potassium ferrate(Ⅵ) as the pre-oxidation agent, poly-aluminum chloride(PAC) and Kaolin as the co-coagulation agents. The residual aluminum morphology was also studied.The consequence was that the ferrate concentration with 4.0 mg· L-1 could improve the removal rate of turbidity, HA and algae, whose value was 94.05%, 91.67% and 90. 78% respectively, and the effect was much better than PAC singly. The pH value affected the efficiency of ferrate pre-oxidation processing mixed water. In acidic condition (pH = 6. 5) the effect was best. Potassium ferrate(Ⅵ) pre-oxidation affected the content and form of residual aluminum. Under the best condition the total aluminum concentration reduced by 51.8%, and especially the dissolved aluminum which poisoned human body decreased by 43.9%.

  2. Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles.

    Science.gov (United States)

    Cheng, Yuanhang; Yang, Qing-Dan; Xiao, Jingyang; Xue, Qifan; Li, Ho-Wa; Guan, Zhiqiang; Yip, Hin-Lap; Tsang, Sai-Wing

    2015-09-16

    Solution processed zinc oxide (ZnO) nanoparticles (NPs) with excellent electron transport properties and a low-temperature process is a viable candidate to replace titanium dioxide (TiO2) as electron transport layer to develop high-efficiency perovskite solar cells on flexible substrates. However, the number of reported high-performance perovskite solar cells using ZnO-NPs is still limited. Here we report a detailed investigation on the chemistry and crystal growth of CH3NH3PbI3 perovskite on ZnO-NP thin films. We find that the perovskite films would severely decompose into PbI2 upon thermal annealing on the bare ZnO-NP surface. X-ray photoelectron spectroscopy (XPS) results show that the hydroxide groups on the ZnO-NP surface accelerate the decomposition of the perovskite films. To reduce the decomposition, we introduce a buffer layer in between the ZnO-NPs and perovskite layers. We find that a commonly used buffer layer with small molecule [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) can slow down but cannot completely avoid the decomposition. On the other hand, a polymeric buffer layer using poly(ethylenimine) (PEI) can effectively separate the ZnO-NPs and perovskite, which allows larger crystal formation with thermal annealing. The power conversion efficiencies of perovskite photovoltaic cells are significantly increased from 6.4% to 10.2% by replacing PC61BM with PEI as the buffer layer.

  3. Symmetry-Based Tight Binding Modeling of Halide Perovskite Semiconductors

    OpenAIRE

    Boyer-Richard, Soline; Katan, Claudine; Traoré, Boubacar; Scholz, Reinhard; Jancu, Jean-Marc; Even, Jacky

    2016-01-01

    International audience; On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX3. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI3 has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structu...

  4. Planar organic-inorganic hybrid perovskite solar cell by electrospray

    OpenAIRE

    Chen, Wenjun

    2015-01-01

    Recently, the organic-inorganic perovskite solar cell has attracted great attention due to the easy processing and rapid developed power conversion efficiency. The tri-halide perovskite CH3NH3PbI3-xClx possessing excellent optical and electronic properties, such as absorption hands span the visible region, long charge carrier diffusion lengths, and appropriate direct band gap, makes them ideal active layer material for photovoltaic devices. In this thesis, electrohydrodynamic spraying is used...

  5. Intrinsic Thermal Instability of Methylammonium Lead Trihalide Perovskite

    OpenAIRE

    Conings, Bert; DRIJKONINGEN, Jeroen; Gauquelin, Nicolas; Babayigit, Aslihan; D'Haen, Jan; D'Olieslager, Lien; Ethirajan, Anitha; Verbeeck, Jo; Manca, Jean; Mosconi, Edoardo; De Angelis, Filippo; BOYEN, Hans-Gerhard

    2015-01-01

    Organolead halide perovskites currently are the new front-runners as light absorbers in hybrid solar cells, as they combine efficiencies passing already 20% with deposition temperatures below 100 degrees C and cheap solution-based fabrication routes. Long-term stability remains a major obstacle for application on an industrial scale. Here, it is demonstrated that significant decomposition effects already occur during annealing of a methylammonium lead triiode perovskite at 85 degrees C even i...

  6. The physics of photon induced degradation of perovskite solar cells

    OpenAIRE

    Pranav H. Joshi; Liang Zhang; Istiaque M. Hossain; Hisham A. Abbas; Ranjith Kottokkaran; Satyapal P. Nehra; Mahendra Dhaka; Max Noack; Vikram L. Dalal

    2016-01-01

    Lead-trihalide perovskite solar cells are an important photovoltaic technology. We investigate the effect of light induced degradation on perovskite solar cells. During exposure, the open-circuit voltage (Voc) of the device increases, whereas the short-circuit current (Isc) shows a decrease. The degradation can be completely recovered using thermal annealing in dark. We develop a model based on light induced generation of ions and migration of these ions inside the material to explain the cha...

  7. Laser Crystallization of Organic-Inorganic Hybrid Perovskite Solar Cells.

    Science.gov (United States)

    Jeon, Taewoo; Jin, Hyeong Min; Lee, Seung Hyun; Lee, Ju Min; Park, Hyung Il; Kim, Mi Kyung; Lee, Keon Jae; Shin, Byungha; Kim, Sang Ouk

    2016-08-23

    Organic-inorganic hybrid perovskites attract enormous research interest for next generation solar energy harvest. Synergistic crystalline structures comprising organic and inorganic components enable solution processing of perovskite films. A reliable crystallization method for perovskites, compatible with fast continuous process over large-area flexible substrates, is crucial for high performance solar cell production. Here, we present laser crystallization of hybrid perovskite solar cells using near-infrared (NIR) laser (λ = 1064 nm). Crystalline morphology of CH3NH3PbI3 (MAPbI3) perovskite films are widely controllable with laser irradiation condition while maintaining film uniformity. Photothermal heating effectively assisted by interfacial photoconversion layers is critical for phase transformation without beam damage of multilayered device structures. Notably, laser crystallization attains higher device performances than conventional thermal annealing. Fast laser crystallization with manufacture level scan rate (1 m min(-1)) demonstrates inverted-type perovskite solar cells with 11.3 and 8.0% efficiencies on typical glass and flexible polymer substrates, respectively, without rigorous device optimization.

  8. Iodomethane-Mediated Organometal Halide Perovskite with Record Photoluminescence Lifetime.

    Science.gov (United States)

    Xu, Weidong; McLeod, John A; Yang, Yingguo; Wang, Yimeng; Wu, Zhongwei; Bai, Sai; Yuan, Zhongcheng; Song, Tao; Wang, Yusheng; Si, Junjie; Wang, Rongbin; Gao, Xingyu; Zhang, Xinping; Liu, Lijia; Sun, Baoquan

    2016-09-07

    Organometallic lead halide perovskites are excellent light harvesters for high-efficiency photovoltaic devices. However, as the key component in these devices, a perovskite thin film with good morphology and minimal trap states is still difficult to obtain. Herein we show that by incorporating a low boiling point alkyl halide such as iodomethane (CH3I) into the precursor solution, a perovskite (CH3NH3PbI3-xClx) film with improved grain size and orientation can be easily achieved. More importantly, these films exhibit a significantly reduced amount of trap states. Record photoluminescence lifetimes of more than 4 μs are achieved; these lifetimes are significantly longer than that of pristine CH3NH3PbI3-xClx films. Planar heterojunction solar cells incorporating these CH3I-mediated perovskites have demonstrated a dramatically increased power conversion efficiency compared to the ones using pristine CH3NH3PbI3-xClx. Photoluminescence, transient absorption, and microwave detected photoconductivity measurements all provide consistent evidence that CH3I addition increases the number of excitons generated and their diffusion length, both of which assist efficient carrier transport in the photovoltaic device. The simple incorporation of alkyl halide to enhance perovskite surface passivation introduces an important direction for future progress on high efficiency perovskite optoelectronic devices.

  9. 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.

  10. Electronic spin state of iron in lower mantle perovskite.

    Science.gov (United States)

    Li, Jie; Struzhkin, Viktor V; Mao, Ho-Kwang; Shu, Jinfu; Hemley, Russell J; Fei, Yingwei; Mysen, Bjorn; Dera, Przemek; Prakapenka, Vitali; Shen, Guoyin

    2004-09-28

    The electronic spin state of iron in lower mantle perovskite is one of the fundamental parameters that governs the physics and chemistry of the most voluminous and massive shell in the Earth. We present experimental evidence for spin-pairing transition in aluminum-bearing silicate perovskite (Mg,Fe)(Si,Al)O(3) under the lower mantle pressures. Our results demonstrate that as pressure increases, iron in perovskite transforms gradually from the initial high-spin state toward the final low-spin state. At 100 GPa, both aluminum-free and aluminum-bearing samples exhibit a mixed spin state. The residual magnetic moment in the aluminum-bearing perovskite is significantly higher than that in its aluminum-free counterpart. The observed spin evolution with pressure can be explained by the presence of multiple iron species and the occurrence of partial spin-paring transitions in the perovskite. Pressure-induced spin-pairing transitions in the perovskite would have important bearing on the magnetic, thermoelastic, and transport properties of the lower mantle, and on the distribution of iron in the Earth's interior.

  11. Two-Photon Absorption in Organometallic Bromide Perovskites.

    Science.gov (United States)

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

    2015-09-22

    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.

  12. Tracking the formation of methylammonium lead triiodide perovskite

    Science.gov (United States)

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

    2015-08-01

    The formation mechanism of perovskite methylammonium lead triiodide (CH3NH3PbI3) was studied with in situ X-ray photoelectron spectroscopy (XPS) on successive depositions of thermally evaporated methylammonium iodide (CH3NH3I) on a lead iodide (PbI2) 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 CH3NH3PbI3. Our most important finding is that during vapour deposition of CH3NH3I onto PbI2, at least two carbon species are present in the resulting material, while only one nitrogen species is present. This suggests that CH3NH3I 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 CH3NH3 substitution with CH3 was evaluated, and electronic structure calculations show that CH3 defects would impact the photovoltaic performance in perovskite solar cells. The possibility that not all A sites in the APbI3 perovskite are occupied by CH3NH3 is therefore an important consideration when evaluating the performance of organometallic trihalide solar cells synthesized using typical approaches.

  13. The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study.

    Science.gov (United States)

    Idígoras, J; Todinova, A; Sánchez-Valencia, J R; Barranco, A; Borrás, A; Anta, J A

    2016-05-11

    The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies. For all of them, we have investigated the influence of these substrate properties on perovskite formation and its degradation by humidity. The effect of selective-hole contact (Spiro-OmeTad and P3HT) layers on the degradation rate by moisture has also been studied. Our IR results reveal the existence of a strong interaction between perovskite and all ZnO materials considered, evidenced by a shift of the peaks related to the N-H vibrational modes. The interaction even induces a morphological change in ZnO nanoparticles after perovskite deposition, pointing to an acid-base reaction that takes place through the NH3(+) groups of the methylammonium cation. Our IR and X-ray diffraction results also indicate that this specific interaction favors perovskite decomposition and PbI2 formation for ZnO/perovskite films subjected to humid conditions. Although no interaction is observed for TiO2, Al2O3, and the hole selective contact, the morphology and chemical nature of both contacts appear to play an important role in the rate of degradation upon exposure to moisture.

  14. New generation perovskite thermal barrier coating materials

    Energy Technology Data Exchange (ETDEWEB)

    Ma, W.; Jarligo, M.O.; Mack, D.E.; Pitzer, D.; Malzbender, J.; Vassen, R.; Stoever, D. [Forschungszentrum Juelich GmbH, Juelich (Germany)

    2008-07-01

    Advanced ceramic materials of perovskite structure have been developed for potential application in thermal barrier coating systems, in an effort to improve the properties of the pre-existing ones like yttria stabilized zirconia. Yb{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} doped strontium zirconate (SrZrO{sub 3}) and barium magnesium tantalate (Ba(Mg{sub 1/3}Ta{sub 2/3})O{sub 3}) of the ABO{sub 3} and complex A(B'{sub 1/3}B''{sub 2/3})O{sub 3} systems respectively, have been synthesized using ball milling prior to solid state sintering. Thermal and mechanical investigations show desirable properties for high temperature coating applications. On atmospheric plasma spraying, the newly developed TBCs reveal promising thermal cycle lifetime above 1300 C. (orig.)

  15. New Generation Perovskite Thermal Barrier Coating Materials

    Science.gov (United States)

    Ma, W.; Jarligo, M. O.; Mack, D. E.; Pitzer, D.; Malzbender, J.; Vaßen, R.; Stöver, D.

    2008-12-01

    Advanced ceramic materials of perovskite structure have been developed for potential application in thermal barrier coating systems, in an effort to improve the properties of the pre-existing ones like yttria-stabilized zirconia. Yb2O3 and Gd2O3 doped strontium zirconate (SrZrO3) and barium magnesium tantalate (Ba(Mg1/3Ta2/3)O3) of the ABO3 and complex A(B'1/3B''2/3)O3 systems, respectively, have been synthesized using ball milling prior to solid state sintering. Thermal and mechanical investigations show desirable properties for high-temperature coating applications. On atmospheric plasma spraying, the newly developed thermal barrier coatings reveal promising thermal cycle lifetime up to 1350 °C.

  16. Ferroelastic Fingerprints in Methylammonium Lead Iodide Perovskite

    KAUST Repository

    Hermes, Ilka M.

    2016-02-12

    Methylammonium lead iodide (MAPbI3) perovskite materials show an outstanding performance in photovoltaic devices. However, certain material properties, especially the possible ferroic behavior, remain unclear. We observed distinct nanoscale periodic domains in the piezoresponse of MAPbI3(Cl) grains. The structure and the orientation of these striped domains indicate ferroelasticity as their origin. By correlating vertical and lateral piezoresponse force microscopy experiments performed at different sample orientations with x-ray diffraction, the preferred domain orientation was suggested to be the a1-a2-phase. The observation of these ferroelastic fingerprints appears to strongly depend on the film texture and thus the preparation route. The formation of the ferroelastic twin domains could be induced by internal strain during the cubic-tetragonal phase transition.

  17. Ultrafast structural dynamics of perovskite superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Woerner, M.; Korff Schmising, C. von; Zhavoronkov, N.; Elsaesser, T. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Berlin (Germany); Bargheer, M. [Universitaet Potsdam, Institut fuer Physik und Astronomie, Potsdam (Germany); Vrejoiu, I.; Hesse, D.; Alexe, M. [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany)

    2009-07-15

    Femtosecond X-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO{sub 3}/PbZr{sub 0.2}Ti{sub 0.8}O{sub 3} (SRO/PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1 ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO{sub 3} (STO) SL. (orig.)

  18. Properties and applications of perovskite proton conductors

    Directory of Open Access Journals (Sweden)

    Eduardo Caetano Camilo de Souza

    2010-09-01

    Full Text Available A brief overview is given of the main types and principles of solid-state proton conductors with perovskite structure. Their properties are summarized in terms of the defect chemistry, proton transport and chemical stability. A good understanding of these subjects allows the manufacturing of compounds with the desired electrical properties, for application in renewable and sustainable energy devices. A few trends and highlights of the scientific advances are given for some classes of protonic conductors. Recent results and future prospect about these compounds are also evaluated. The high proton conductivity of barium cerate and zirconate based electrolytes lately reported in the literature has taken these compounds to a highlight position among the most studied conductor ceramic materials.

  19. Fine control of perovskite-layered morphology and composition via sequential deposition crystallization process towards improved perovskite solar cells

    Science.gov (United States)

    Luo, Yi; Meng, Fanli; Zhao, Erfei; Zheng, Yan-Zhen; Zhou, Yali; Tao, Xia

    2016-04-01

    The ability to prepare high coverage and compact perovskite films via solution-based crystallization manipulation processes still represents a vital issue towards improving the ultimate photoelectric conversion efficiency of devices. In this work, we prepare the active perovskite layer by means of sequential deposition crystallization process i.e. dipping PbI2-infiltrated TiO2 film within CH3NH3I solution from 20s to 60s. The morphology and thickness of the as-prepared perovskite layer, and its overall performance superiority are investigated. X-ray diffraction (XRD) reveals that a maximum conversion of PbI2 to perovskite is completed upon applying a sequential deposition crystallization process of 40s. Field emission scanning electron microscope (FESEM) demonstrates that the coverage of the perovskite capping layer exhibits a trend from rise to decline in the whole dipping time from 20s to 60s. By fine control of the dipping time, a 620 nm-thickness compact perovskite active layer is obtained at the optimized dipping time of 40s and is verified to possess strong light absorption and high electron extraction efficiency, leading to a higher photocurrent. By further optimizing the mesoporous TiO2 film thickness, a high photocurrent of 23.98 mA cm-2 and an efficiency of 13.47% are achieved.

  20. Selective dissolution of halide perovskites as a step towards recycling solar cells.

    Science.gov (United States)

    Kim, Byeong Jo; Kim, Dong Hoe; Kwon, Seung Lee; Park, So Yeon; Li, Zhen; Zhu, Kai; Jung, Hyun Suk

    2016-05-23

    Most research on perovskite solar cells has focused on improving power-conversion efficiency and stability. However, if one could refurbish perovskite solar cells, their stability might not be a critical issue. From the perspective of cost effectiveness, if failed, perovskite solar cells could be collected and recycled; reuse of their gold electrodes and transparent conducting glasses could reduce the price per watt of perovskite photovoltaic modules. Herein, we present a simple and effective method for removing the perovskite layer and reusing the mesoporous TiO2-coated transparent conducting glass substrate via selective dissolution. We find that the perovskite layer can be easily decomposed in polar aprotic solvents because of the reaction between polar aprotic solvents and Pb(2+) cations. After 10 cycles of recycling, a mesoporous TiO2-coated transparent conducting glass substrate-based perovskite solar cell still shows a constant power-conversion efficiency, thereby demonstrating the possibility of recycling perovskite solar cells.

  1. Chitosan-Assisted Crystallization and Film Forming of Perovskite Crystals through Biomineralization.

    Science.gov (United States)

    Yang, Yang; Sun, Chen; Yip, Hin-Lap; Sun, Runcang; Wang, Xiaohui

    2016-03-18

    Biomimetic mineralization is a powerful approach for the synthesis of advanced composite materials with hierarchical organization and controlled structure. Herein, chitosan was introduced into a perovskite precursor solution as a biopolymer additive to control the crystallization and to improve the morphology and film-forming properties of a perovskite film by way of biomineralization. The biopolymer additive was able to control the size and morphology of the perovskite crystals and helped to form smooth films. The mechanism of chitosan-mediated nucleation and growth of the perovskite crystals was explored. As a possible application, the chitosan-perovskite composite film was introduced into a planar heterojunction solar cell and increased power conversion efficiency relative to that observed for the pristine perovskite film was achieved. The biomimetic mineralization method proposed in this study provides an alternative way of preparing perovskite crystals with well-controlled morphology and properties and extends the applications of perovskite crystals in photoelectronic fields, including planar-heterojunction solar cells.

  2. The Electrical Conductivity of Post-Perovskite in Earth's D" Layer

    National Research Council Canada - National Science Library

    Kenji Ohta; Suzue Onoda; Kei Hirose; Ryosuke Sinmyo; Katsuya Shimizu; Nagayoshi Sata; Yasuo Ohishi; Akira Yasuhara

    2008-01-01

    Recent discovery of a phase transition from perovskite to post-perovskite suggests that the physical properties of Earth's lowermost mantle, called the D" layer, may be different from those of the overlying mantle...

  3. Growth and Characterization of PDMS-Stamped Halide Perovskite Single Microcrystals

    NARCIS (Netherlands)

    Khoram, P.; Brittman, S.; Dzik, W.I.; Reek, J.N.H.; Garneett, E.C.

    2016-01-01

    Recently, halide perovskites have attracted considerable attention for optoelectronic applications, but further progress in this field requires a thorough understanding of the fundamental properties of these materials. Studying perovskites in their single-crystalline form provides a model system for

  4. Growth and Characterization of PDMS-Stamped Halide Perovskite Single Microcrystals

    NARCIS (Netherlands)

    Khoram, P.; Brittman, S.; Dzik, W.I.; Reek, J.N.H.; Garneett, E.C.

    2016-01-01

    Recently, halide perovskites have attracted considerable attention for optoelectronic applications, but further progress in this field requires a thorough understanding of the fundamental properties of these materials. Studying perovskites in their single-crystalline form provides a model system for

  5. Selective dissolution of halide perovskites as a step towards recycling solar cells

    Science.gov (United States)

    Kim, Byeong Jo; Kim, Dong Hoe; Kwon, Seung Lee; Park, So Yeon; Li, Zhen; Zhu, Kai; Jung, Hyun Suk

    2016-05-01

    Most research on perovskite solar cells has focused on improving power-conversion efficiency and stability. However, if one could refurbish perovskite solar cells, their stability might not be a critical issue. From the perspective of cost effectiveness, if failed, perovskite solar cells could be collected and recycled; reuse of their gold electrodes and transparent conducting glasses could reduce the price per watt of perovskite photovoltaic modules. Herein, we present a simple and effective method for removing the perovskite layer and reusing the mesoporous TiO2-coated transparent conducting glass substrate via selective dissolution. We find that the perovskite layer can be easily decomposed in polar aprotic solvents because of the reaction between polar aprotic solvents and Pb2+ cations. After 10 cycles of recycling, a mesoporous TiO2-coated transparent conducting glass substrate-based perovskite solar cell still shows a constant power-conversion efficiency, thereby demonstrating the possibility of recycling perovskite solar cells.

  6. Research Update: Overview of progress about efficiency and stability on perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2016-09-01

    Full Text Available Due to the high conversion efficiency, organic-inorganic hybrid perovskite (CH3NH3PbI3 solar cells are investigated for new practical energy resources for our future society. However, the perovskite solar cells have been quite unstable devices. In this manuscript, the history of perovskite solar cells is introduced, and then, the efforts to improve and understand the stability issue of perovskite solar cells are summarized.

  7. Planar Heterojunction Perovskite Solar Cells Incorporating Metal-Organic Framework Nanocrystals.

    Science.gov (United States)

    Chang, Ting-Hsiang; Kung, Chung-Wei; Chen, Hsin-Wei; Huang, Tzu-Yen; Kao, Sheng-Yuan; Lu, Hsin-Che; Lee, Min-Han; Boopathi, Karunakara Moorthy; Chu, Chih-Wei; Ho, Kuo-Chuan

    2015-11-25

    Zr-based porphyrin metal-organic framework (MOF-525) nanocrystals with a crystal size of about 140 nm are synthesized and incorporated into perovskite solar cells. The morphology and crystallinity of the perovskite thin film are enhanced since the micropores of MOF-525 allow the crystallization of perovskite to occur inside; this observation results in a higher cell efficiency of the obtained MOF/perovskite solar cell.

  8. Recent Advances in Interface Engineering for Planar Heterojunction Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Wei Yin

    2016-06-01

    Full Text Available Organic-inorganic hybrid perovskite solar cells are considered as one of the most promising next-generation solar cells due to their advantages of low-cost precursors, high power conversion efficiency (PCE and easy of processing. In the past few years, the PCEs have climbed from a few to over 20% for perovskite solar cells. Recent developments demonstrate that perovskite exhibits ambipolar semiconducting characteristics, which allows for the construction of planar heterojunction (PHJ perovskite solar cells. PHJ perovskite solar cells can avoid the use of high-temperature sintered mesoporous metal oxides, enabling simple processing and the fabrication of flexible and tandem perovskite solar cells. In planar heterojunction materials, hole/electron transport layers are introduced between a perovskite film and the anode/cathode. The hole and electron transporting layers are expected to enhance exciton separation, charge transportation and collection. Further, the supporting layer for the perovskite film not only plays an important role in energy-level alignment, but also affects perovskite film morphology, which have a great effect on device performance. In addition, interfacial layers also affect device stability. In this review, recent progress in interfacial engineering for PHJ perovskite solar cells will be reviewed, especially with the molecular interfacial materials. The supporting interfacial layers for the optimization of perovskite films will be systematically reviewed. Finally, the challenges remaining in perovskite solar cells research will be discussed.

  9. Recent Advances in Interface Engineering for Planar Heterojunction Perovskite Solar Cells.

    Science.gov (United States)

    Yin, Wei; Pan, Lijia; Yang, Tingbin; Liang, Yongye

    2016-06-25

    Organic-inorganic hybrid perovskite solar cells are considered as one of the most promising next-generation solar cells due to their advantages of low-cost precursors, high power conversion efficiency (PCE) and easy of processing. In the past few years, the PCEs have climbed from a few to over 20% for perovskite solar cells. Recent developments demonstrate that perovskite exhibits ambipolar semiconducting characteristics, which allows for the construction of planar heterojunction (PHJ) perovskite solar cells. PHJ perovskite solar cells can avoid the use of high-temperature sintered mesoporous metal oxides, enabling simple processing and the fabrication of flexible and tandem perovskite solar cells. In planar heterojunction materials, hole/electron transport layers are introduced between a perovskite film and the anode/cathode. The hole and electron transporting layers are expected to enhance exciton separation, charge transportation and collection. Further, the supporting layer for the perovskite film not only plays an important role in energy-level alignment, but also affects perovskite film morphology, which have a great effect on device performance. In addition, interfacial layers also affect device stability. In this review, recent progress in interfacial engineering for PHJ perovskite solar cells will be reviewed, especially with the molecular interfacial materials. The supporting interfacial layers for the optimization of perovskite films will be systematically reviewed. Finally, the challenges remaining in perovskite solar cells research will be discussed.

  10. Solar cells, structures including organometallic halide perovskite monocrystalline films, and methods of preparation thereof

    KAUST Repository

    Bakr, Osman M.

    2017-03-02

    Embodiments of the present disclosure provide for solar cells including an organometallic halide perovskite monocrystalline film (see fig. 1.1B), other devices including the organometallic halide perovskite monocrystalline film, methods of making organometallic halide perovskite monocrystalline film, and the like.

  11. Influence of void-free perovskite capping layer on the charge recombination process in high performance CH3NH3PbI3 perovskite solar cells

    Science.gov (United States)

    Fu, Kunwu; Nelson, Christopher T.; Scott, Mary Cooper; Minor, Andrew; Mathews, Nripan; Wong, Lydia Helena

    2016-02-01

    The stunning rise of methylammonium lead iodide perovskite material as a light harvesting material in recent years has drawn much attention in the photovoltaic community. Here, we investigated in detail the uniform and void-free perovskite capping layer in the mesoscopic perovskite devices and found it to play a critical role in determining device performance and charge recombination process. Compared to the rough surface with voids of the perovskite layer, surface of the perovskite capping layer obtained from sequential deposition process is much more uniform with less void formation and distribution within the TiO2 mesoscopic scaffold is more homogeneous, leading to much improved photovoltaic parameters of the devices. The impact of void free perovskite capping layer surface on the charge recombination processes within the mesoscopic perovskite solar cells is further scrutinized via charge extraction measurement. Modulation of precursor solution concentrations in order to further improve the perovskite layer surface morphology leads to higher efficiency and lower charge recombination rates. Inhibited charge recombination in these solar cells also matches with the higher charge density and slower photovoltage decay profiles measured.The stunning rise of methylammonium lead iodide perovskite material as a light harvesting material in recent years has drawn much attention in the photovoltaic community. Here, we investigated in detail the uniform and void-free perovskite capping layer in the mesoscopic perovskite devices and found it to play a critical role in determining device performance and charge recombination process. Compared to the rough surface with voids of the perovskite layer, surface of the perovskite capping layer obtained from sequential deposition process is much more uniform with less void formation and distribution within the TiO2 mesoscopic scaffold is more homogeneous, leading to much improved photovoltaic parameters of the devices. The impact of

  12. Employing Lead Thiocyanate Additive to Reduce the Hysteresis and Boost the Fill Factor of Planar Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Weijun [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan 430072 China; National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Xiao, Chuanxiao [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Wang, Changlei [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Saparov, Bayrammurad [Department of Mechanical Engineering and Materials Science, Duke University, Durham NC 27708 USA; Department of Chemistry, Duke University, Durham NC 27708 USA; Duan, Hsin-Sheng [Department of Mechanical Engineering and Materials Science, Duke University, Durham NC 27708 USA; Zhao, Dewei [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Xiao, Zewen [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Schulz, Philip [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Harvey, Steven P. [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Liao, Weiqiang [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Meng, Weiwei [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Yu, Yue [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Cimaroli, Alexander J. [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA; Jiang, Chun-Sheng [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Zhu, Kai [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Al-Jassim, Mowafak [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden CO 80401 USA; Fang, Guojia [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan 430072 China; Mitzi, David B. [Department of Mechanical Engineering and Materials Science, Duke University, Durham NC 27708 USA; Department of Chemistry, Duke University, Durham NC 27708 USA; Yan, Yanfa [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo OH 43606 USA

    2016-05-04

    Lead thiocyanate in the perovskite precursor can increase the grain size of a perovskite thin film and reduce the conductivity of the grain boundaries, leading to perovskite solar cells with reduced hysteresis and enhanced fill factor. A planar perovskite solar cell with grain boundary and interface passivation achieves a steady-state efficiency of 18.42%.

  13. Employing Lead Thiocyanate Additive to Reduce the Hysteresis and Boost the Fill Factor of Planar Perovskite Solar Cells.

    Science.gov (United States)

    Ke, Weijun; Xiao, Chuanxiao; Wang, Changlei; Saparov, Bayrammurad; Duan, Hsin-Sheng; Zhao, Dewei; Xiao, Zewen; Schulz, Philip; Harvey, Steven P; Liao, Weiqiang; Meng, Weiwei; Yu, Yue; Cimaroli, Alexander J; Jiang, Chun-Sheng; Zhu, Kai; Al-Jassim, Mowafak; Fang, Guojia; Mitzi, David B; Yan, Yanfa

    2016-07-01

    Lead thiocyanate in the perovskite precursor can increase the grain size of a perovskite thin film and reduce the conductivity of the grain boundaries, leading to perovskite solar cells with reduced hysteresis and enhanced fill factor. A planar perovskite solar cell with grain boundary and interface passivation achieves a steady-state efficiency of 18.42%.

  14. Preparation of Potassium Ferrate and Its Effectiveness on the Removal of As(III) and Pb(II)%高铁酸钾的制备及其对水中 As(III)、Pb(II)的去除效能研究

    Institute of Scientific and Technical Information of China (English)

    王颖馨; 周雪婷; 卜洪龙; 蓝冰燕; 李来胜; 孙强强; 房思雅

    2015-01-01

    利用正交法得出次氯酸盐氧化法合成高铁酸钾的最佳工艺条件,以FTIR、XRD、SEM、EDS、TEM表征证实其纯度可达95%.在砷、铅单独及复合污染的处理中比较了K2 FeO4投加量、起始pH对处理效果的影响.实验表明,当砷、铅起始质量浓度为2 mg/L,溶液pH 6.5,铁砷质量浓度比为16或铁铅质量浓度比为4时,沉淀后水中砷、铅质量浓度均可低于10μg/L;K2 FeO4同样能有效处理砷铅复合污染,在K2 FeO4投加量为24 mg/L时,对砷、铅的去除率分别为99.30%和100%;与单独污染相比,低K2 FeO4投加量下,砷与铅的竞争关系明显.通过结合Visual MINTEQ化学平衡模拟软件对实验机理进行分析表明:高铁酸钾通过氧化、电中和及表面络合等作用去除水中砷、铅.%Potassium ferrate ( K2 FeO4 ) was synthesized by hypochlorite oxidation.Orthogonal method was applied to optimize the synthesis process.The obtained K2 FeO4 had a purity of 95% or higher.The synthesized K2 FeO4 was used as a coagulant to remove As( III) and Pb( II) in single and bi-solute systems.Effects of K2 FeO4 dosage and operating pH on the removal of As( III) and Pb( II) were studied.In the single system, results shows that at pH 6.5, Fe/As=16 ( wt/wt) and Fe/Pb=4 ( wt/wt) , the residual As and Pb were less than 10μg/L.In the bi-solute system, ferrate could remove As and Pb simultaneously.When ferrate dose was 24 mg/L, the removal rates of As and Pb were 99.30%and 100%, respectively.At low ferrate dose, the competitive adsorption behavior of As( III) and Pb( II) in the bi-solute system was observed.Visual MINTEQ software was used to calculate and sim-ulate metal speciation in solution at equilibrium aiming at elucidate the removal mechanism of As and Pb by potassi-um ferrate.

  15. Dielectric properties of hybrid perovskites and drift-diffusion modeling of perovskite cells

    OpenAIRE

    Pedesseau, Laurent; Kepenekian, M.; Sapori, Daniel; Huang, Y.; Rolland, Alain; Beck, Alexandre; C. Cornet; Durand, Olivier; Wang, Shijian; Katan, Claudine; Even, Jacky

    2016-01-01

    International audience; A method based on DFT is used to obtained dielectric profiles. The high frequency ε∞(z) and the static εs(z) dielectric profiles are compared for 3D, 2D-3D and 2D Hybrid Organic Perovskites (HOP). A dielectric confinement is observed for the 2D materials between the high dielectric constant of the inorganic part and the low dielectric constant of the organic part. The effect of the ionic contribution on the dielectric constant is also shown. The quantum and dielectric ...

  16. A Long-Term View on Perovskite Optoelectronics.

    Science.gov (United States)

    Docampo, Pablo; Bein, Thomas

    2016-02-16

    Recently, metal halide perovskite materials have become an exciting topic of research for scientists of a wide variety of backgrounds. Perovskites have found application in many fields, starting from photovoltaics and now also making an impact in light-emitting applications. This new class of materials has proven so interesting since it can be easily solution processed while exhibiting materials properties approaching the best inorganic optoelectronic materials such as GaAs and Si. In photovoltaics, in only 3 years, efficiencies have rapidly increased from an initial value of 3.8% to over 20% in recent reports for the commonly employed methylammonium lead iodide (MAPI) perovskite. The first light emitting diodes and light-emitting electrochemical cells have been developed already exhibiting internal quantum efficiencies exceeding 15% for the former and tunable light emission spectra. Despite their processing advantages, perovskite optoelectronic materials suffer from several drawbacks that need to be overcome before the technology becomes industrially relevant and hence achieve long-term application. Chief among these are the sensitivity of the structure toward moisture and crystal phase transitions in the device operation regime, unreliable device performance dictated by the operation history of the device, that is, hysteresis, the inherent toxicity of the structure, and the high cost of the employed charge selective contacts. In this Account, we highlight recent advances toward the long-term viability of perovskite photovoltaics. We identify material decomposition routes and suggest strategies to prevent damage to the structure. In particular, we focus on the effect of moisture upon the structure and stabilization of the material to avoid phase transitions in the solar cell operating range. Furthermore, we show strategies to achieve low-cost chemistries for the development of hole transporters for perovskite solar cells, necessary to be able to compete with other

  17. Perovskite solar cells - An overview of critical issues

    Science.gov (United States)

    Djurišić, A. B.; Liu, F. Z.; Tam, H. W.; Wong, M. K.; Ng, A.; Surya, C.; Chen, W.; He, Z. B.

    2017-05-01

    Perovskite solar cell research has been attracting increasing attention in recent years. In this review paper, we will provide an overview of the recent developments in terms of material composition, deposition techniques, and the device architecture (the choice of charge transport layers and electrodes). Then, we will critically discuss some of the major problems, namely device stability, hysteresis, environmental implications due to the presence of a toxic metal (lead), and difficulties in fabrication of large area and/or flexible devices. In addition, we will also discuss tandem cells and modules, as well as the application of perovskites in other devices and the integration of perovskite solar cells with other devices. Finally, we discuss future outlook and important issues which need to be addressed for the wide scale applications of these devices. Lifetime and stability are identified as the key issue to be addressed for wide scale applications, and the majority of environmental impact is due to the use of organic solvents or other components in the device, not the lead-containing perovskite absorber. The standardisation of the testing conditions and more studies involving outdoor testing are needed for convincing demonstrations of good stability as opposed to dark storage testing. Another key issue is upscaling and reproducibility of the film preparation, which can be problematic due to high sensitivity of the perovskite film to the processing conditions. To overcome these obstacles multilaboratory collaborative efforts would be highly desirable.

  18. Stabilized Wide Bandgap Perovskite Solar Cells by Tin Substitution.

    Science.gov (United States)

    Yang, Zhibin; Rajagopal, Adharsh; Jo, Sae Byeok; Chueh, Chu-Chen; Williams, Spencer; Huang, Chun-Chih; Katahara, John K; Hillhouse, Hugh W; Jen, Alex K-Y

    2016-12-14

    Wide bandgap MAPb(I1-yBry)3 perovskites show promising potential for application in tandem solar cells. However, unstable photovoltaic performance caused by phase segregation has been observed under illumination when y is above 0.2. Herein, we successfully demonstrate stabilization of the I/Br phase by partially replacing Pb(2+) with Sn(2+) and verify this stabilization with X-ray diffractometry and transient absorption spectroscopy. The resulting MAPb0.75Sn0.25(I1-yBry)3 perovskite solar cells show stable photovoltaic performance under continuous illumination. Among these cells, the one based on MAPb0.75Sn0.25(I0.4Br0.6)3 perovskite shows the highest efficiency of 12.59% with a bandgap of 1.73 eV, which make it a promising wide bandgap candidate for application in tandem solar cells. The engineering of internal bonding environment by partial Sn substitution is believed to be the main reason for making MAPb0.75Sn0.25(I1-yBry)3 perovskite less vulnerable to phase segregation during the photostriction under illumination. Therefore, this study establishes composition engineering of the metal site as a promising strategy to impart phase stability in hybrid perovskites under illumination.

  19. Interface and Composition Analysis on Perovskite Solar Cells.

    Science.gov (United States)

    Matteocci, Fabio; Busby, Yan; Pireaux, Jean-Jacques; Divitini, Giorgio; Cacovich, Stefania; Ducati, Caterina; Di Carlo, Aldo

    2015-12-02

    Organometal halide (hybrid) perovskite solar cells have been fabricated following four different deposition procedures and investigated in order to find correlations between the solar cell characteristics/performance and their structure and composition as determined by combining depth-resolved imaging with time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), and analytical scanning transmission electron microscopy (STEM). The interface quality is found to be strongly affected by the perovskite deposition procedure, and in particular from the environment where the conversion of the starting precursors into the final perovskite is performed (air, nitrogen, or vacuum). The conversion efficiency of the precursors into the hybrid perovskite layer is compared between the different solar cells by looking at the ToF-SIMS intensities of the characteristic molecular fragments from the perovskite and the precursor materials. Energy dispersive X-ray spectroscopy in the STEM confirms the macroscopic ToF-SIMS findings and allows elemental mapping with nanometer resolution. Clear evidence for iodine diffusion has been observed and related to the fabrication procedure.

  20. Robust high-κ response in molecularly thin perovskite nanosheets.

    Science.gov (United States)

    Osada, Minoru; Akatsuka, Kosho; Ebina, Yasuo; Funakubo, Hiroshi; Ono, Kanta; Takada, Kazunori; Sasaki, Takayoshi

    2010-09-28

    Size-induced suppression of permittivity in perovskite thin films is a fundamental problem that has remained unresolved for decades. This size-effect issue becomes increasingly important due to the integration of perovskite nanofilms into high-κ capacitors, as well as concerns that intrinsic size effects may limit their device performance. Here, we report a new approach to produce robust high-κ nanodielectrics using perovskite nanosheet (Ca2Nb3O10), a new class of nanomaterials that is derived from layered compounds by exfoliation. By a solution-based bottom-up approach using perovskite nanosheets, we have successfully fabricated multilayer nanofilms directly on SrRuO3 or Pt substrates without any interfacial dead layers. These nanofilms exhibit high dielectric constant (>200), the largest value seen so far in perovskite films with a thickness down to 10 nm. Furthermore, the superior high-κ properties are a size-effect-free characteristic with low leakage current density (<10(-7) A cm(-2)). Our work provides a key for understanding the size effect and also represents a step toward a bottom-up paradigm for future high-κ devices.

  1. Calculation studies on point defects in perovskite solar cells

    Science.gov (United States)

    Han, Dan; Dai, Chenmin; Chen, Shiyou

    2017-01-01

    The close-to-optimal band gap, large absorption coefficient, low manufacturing cost and rapid increase in power conversion efficiency make the organic–inorganic hybrid halide (CH3NH3PbI3) and related perovskite solar cells very promising for commercialization. The properties of point defects in the absorber layer semiconductors have important influence on the photovoltaic performance of solar cells, so the investigation on the defect properties in the perovskite semiconductors is necessary for the optimization of their photovoltaic performance. In this work, we give a brief review to the first-principles calculation studies on the defect properties in a series of perovskite semiconductors, including the organic–inorganic hybrid perovskites and inorganic halide perovskites. Experimental identification of these point defects and characterization of their properties are called for. Project supported by the National Natural Science Foundation of China (No. 61574059), the Shanghai Rising-Star Program (No. 14QA1401500), the Shu-Guang Program (15SG20), and the CC of ECNU.

  2. Effect of Perovskite Film Preparation on Performance of Solar Cells

    Directory of Open Access Journals (Sweden)

    Yaxian Pei

    2016-01-01

    Full Text Available For the perovskite solar cells (PSCs, the performance of the PSCs has become the focus of the research by improving the crystallization and morphology of the perovskite absorption layer. In this thesis, based on the structure of mesoporous perovskite solar cells (MPSCs, we designed the experiments to improve the photovoltaic performance of the PSCs by improved processing technique, which mainly includes the following two aspects. Before spin-coating PbI2 solution, we control the substrate temperature to modify the crystal quality and morphology of perovskite films. On the other hand, before annealing, we keep PbI2 films for the different drying time at room temperature to optimize films morphology. In our trials, it was found that the substrate temperature is more important in determining the photovoltaic performance than drying time. These results indicate that the crystallization and morphology of perovskite films affect the absorption intensity and obviously influence the short circuit current density of MPSCs. Utilizing films prepared by mentioning two methods, MPSCs with maximum power conversion efficiency of over 4% were fabricated for the active area of 0.5 × 0.5 cm2.

  3. Electron-phonon coupling in hybrid lead halide perovskites

    Science.gov (United States)

    Wright, Adam D.; Verdi, Carla; Milot, Rebecca L.; Eperon, Giles E.; Pérez-Osorio, Miguel A.; Snaith, Henry J.; Giustino, Feliciano; Johnston, Michael B.; Herz, Laura M.

    2016-05-01

    Phonon scattering limits charge-carrier mobilities and governs emission line broadening in hybrid metal halide perovskites. Establishing how charge carriers interact with phonons in these materials is therefore essential for the development of high-efficiency perovskite photovoltaics and low-cost lasers. Here we investigate the temperature dependence of emission line broadening in the four commonly studied formamidinium and methylammonium perovskites, HC(NH2)2PbI3, HC(NH2)2PbBr3, CH3NH3PbI3 and CH3NH3PbBr3, and discover that scattering from longitudinal optical phonons via the Fröhlich interaction is the dominant source of electron-phonon coupling near room temperature, with scattering off acoustic phonons negligible. We determine energies for the interacting longitudinal optical phonon modes to be 11.5 and 15.3 meV, and Fröhlich coupling constants of ~40 and 60 meV for the lead iodide and bromide perovskites, respectively. Our findings correlate well with first-principles calculations based on many-body perturbation theory, which underlines the suitability of an electronic band-structure picture for describing charge carriers in hybrid perovskites.

  4. Halide Perovskites: Poor Man's High-Performance Semiconductors.

    Science.gov (United States)

    Stoumpos, Constantinos C; Kanatzidis, Mercouri G

    2016-07-01

    Halide perovskites are a rapidly developing class of medium-bandgap semiconductors which, to date, have been popularized on account of their remarkable success in solid-state heterojunction solar cells raising the photovoltaic efficiency to 20% within the last 5 years. As the physical properties of the materials are being explored, it is becoming apparent that the photovoltaic performance of the halide perovskites is just but one aspect of the wealth of opportunities that these compounds offer as high-performance semiconductors. From unique optical and electrical properties stemming from their characteristic electronic structure to highly efficient real-life technological applications, halide perovskites constitute a brand new class of materials with exotic properties awaiting discovery. The nature of halide perovskites from the materials' viewpoint is discussed here, enlisting the most important classes of the compounds and describing their most exciting properties. The topics covered focus on the optical and electrical properties highlighting some of the milestone achievements reported to date but also addressing controversies in the vastly expanding halide perovskite literature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Electron-phonon coupling in hybrid lead halide perovskites.

    Science.gov (United States)

    Wright, Adam D; Verdi, Carla; Milot, Rebecca L; Eperon, Giles E; Pérez-Osorio, Miguel A; Snaith, Henry J; Giustino, Feliciano; Johnston, Michael B; Herz, Laura M

    2016-05-26

    Phonon scattering limits charge-carrier mobilities and governs emission line broadening in hybrid metal halide perovskites. Establishing how charge carriers interact with phonons in these materials is therefore essential for the development of high-efficiency perovskite photovoltaics and low-cost lasers. Here we investigate the temperature dependence of emission line broadening in the four commonly studied formamidinium and methylammonium perovskites, HC(NH2)2PbI3, HC(NH2)2PbBr3, CH3NH3PbI3 and CH3NH3PbBr3, and discover that scattering from longitudinal optical phonons via the Fröhlich interaction is the dominant source of electron-phonon coupling near room temperature, with scattering off acoustic phonons negligible. We determine energies for the interacting longitudinal optical phonon modes to be 11.5 and 15.3 meV, and Fröhlich coupling constants of ∼40 and 60 meV for the lead iodide and bromide perovskites, respectively. Our findings correlate well with first-principles calculations based on many-body perturbation theory, which underlines the suitability of an electronic band-structure picture for describing charge carriers in hybrid perovskites.

  6. Elusive Presence of Chloride in Mixed Halide Perovskite Solar Cells.

    Science.gov (United States)

    Colella, Silvia; Mosconi, Edoardo; Pellegrino, Giovanna; Alberti, Alessandra; Guerra, Valentino L P; Masi, Sofia; Listorti, Andrea; Rizzo, Aurora; Condorelli, Guglielmo Guido; De Angelis, Filippo; Gigli, Giuseppe

    2014-10-16

    The role of chloride in the MAPbI3-xClx perovskite is still limitedly understood, albeit subjected of much debate. Here, we present a combined angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and first-principles DFT modeling to investigate the MAPbI3-xClx/TiO2 interface. AR-XPS analyses carried out on ad hoc designed bilayers of MAPbI3-xClx perovskite deposited onto a flat TiO2 substrate reveal that the chloride is preferentially located in close proximity to the perovskite/TiO2 interface. DFT calculations indicate the preferential location of chloride at the TiO2 interface compared to the bulk perovskite due to an increased chloride-TiO2 surface affinity. Furthermore, our calculations clearly demonstrate an interfacial chloride-induced band bending, creating a directional "electron funnel" that may improve the charge collection efficiency of the device and possibly affecting also recombination pathways. Our findings represent a step forward to the rationalization of the peculiar properties of mixed halide perovskite, allowing one to further address material and device design issues.

  7. X-ray Scintillation in Lead Halide Perovskite Crystals

    Science.gov (United States)

    Birowosuto, M. D.; Cortecchia, D.; Drozdowski, W.; Brylew, K.; Lachmanski, W.; Bruno, A.; Soci, C.

    2016-11-01

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray excited thermoluminescence measurements indicate the absence of deep traps and a very small density of shallow trap states, which lessens after-glow effects. All perovskite single crystals exhibit high X-ray excited luminescence yields of >120,000 photons/MeV at low temperature. Although thermal quenching is significant at room temperature, the large exciton binding energy of 2D (EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites, and moderate light yield of 9,000 photons/MeV can be achieved even at room temperature. This highlights the potential of 2D metal halide perovskites for large-area and low-cost scintillator devices for medical, security and scientific applications.

  8. Review on palladium-containing perovskites: synthesis, physico-chemical properties and applications in catalysis.

    Science.gov (United States)

    Essoumhi, Abdellatif; El Kazzouli, Saïd; Bousmina, Mosto

    2014-02-01

    This review reports on the recent advances in the synthesis and physico-chemical properties of palladium-containing perovskites. Initially, the perovskite structure is briefly reviewed, then palladium-containing perovskites synthesis and physico-chemical properties are detailed. The applications of palladium-containing perovskites in catalysis; namely, NO reduction, methane combustion, methanol as well as ethanol oxidation, are briefly highlighted. The involvement and the important contribution of palladium-containing perovskites in cross-coupling reactions, especially Suzuki-Miyaura, Sonogashira, Ulmann and Grignard, are discussed.

  9. Bismuth Based Hybrid Perovskites A3Bi2 I9 (A: Methylammonium or Cesium) for Solar Cell Application.

    Science.gov (United States)

    Park, Byung-Wook; Philippe, Bertrand; Zhang, Xiaoliang; Rensmo, Håkan; Boschloo, Gerrit; Johansson, Erik M J

    2015-11-18

    Low-toxic bismuth-based perovskites are prepared for the possible replacement of lead perovskite in solar cells. The perovskites have a hexagonal crystalline phase and light absorption in the visible region. A power conversion efficiency of over 1% is obtained for a solar cell with Cs3 Bi2 I9 perovskite, and it is concluded that bismuth perovskites have very promising properties for further development in solar cells.

  10. Paintable Carbon-Based Perovskite Solar Cells with Engineered Perovskite/Carbon Interface Using Carbon Nanotubes Dripping Method.

    Science.gov (United States)

    Ryu, Jaehoon; Lee, Kisu; Yun, Juyoung; Yu, Haejun; Lee, Jungsup; Jang, Jyongsik

    2017-08-07

    Paintable carbon electrode-based perovskite solar cells (PSCs) are of particular interest due to their material and fabrication process costs, as well as their moisture stability. However, printing the carbon paste on the perovskite layer limits the quality of the interface between the perovskite layer and carbon electrode. Herein, an attempt to enhance the performance of the paintable carbon-based PSCs is made using a modified solvent dripping method that involves dripping of the carbon nanotubes (CNTs), which is dispersed in chlorobenzene solution. This method allows CNTs to penetrate into both the perovskite film and carbon electrode, facilitating fast hole transport between the two layers. Furthermore, this method is results in increased open circuit voltage (Voc ) and fill factor (FF), providing better contact at the perovskite/carbon interfaces. The best devices made with CNT dripping show 13.57% power conversion efficiency and hysteresis-free performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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.

  12. Mixture interlayer for high performance organic-inorganic perovskite photodetectors

    Science.gov (United States)

    Tang, Feng; Chen, Qi; Chen, Lei; Ye, Fengye; Cai, Jinhua; Chen, Liwei

    2016-09-01

    Organic-inorganic perovskites are promising light absorbing active materials for photodetectors; however, the performance of current organic-inorganic perovskite-based photodetectors are limited by the high dark current due to hole injection at the cathode interlayer typically composed of fullerene derivatives. We have developed a mixture interlayer by simply blending polymethyl methacrylate (PMMA) with [6,6]-phenyl-C61-butyric acidmethyl ester (PCBM). Scanning Kelvin probe microscopy imaging reveals that the presence of PMMA reduced the work function of the PCBM:PMMA interlayer, which leads to increased energy barrier for hole injection and better hole-blocking property. Optimized perovskite photodetector with PCBM:PMMA hole-blocking interlayer exhibits a high detectivity of 1.1 × 1013 Jones, a broad linear dynamic range of 112 dB, and a fast response time of 2.2 μs.

  13. Conformal Organohalide Perovskites Enable Lasing on Spherical Resonators

    KAUST Repository

    Sutherland, Brandon R.

    2014-10-28

    © 2014 American Chemical Society. Conformal integration of semiconductor gain media is broadly important in on-chip optical communication technology. Here we deploy atomic layer deposition to create conformally deposited organohalide perovskites-an attractive semiconducting gain medium-with the goal of achieving coherent light emission on spherical optical cavities. We demonstrate the high quality of perovskite gain media fabricated with this method, achieving optical gain in the nanosecond pulse regime with a threshold for amplified spontaneous emission of 65 ± 8 μJ cm-2. Through variable stripe length measurements, we report a net modal gain of 125 ± 22 cm-1 and a gain bandwidth of 50 ± 14 meV. Leveraging the high quality of the gain medium, we conformally coat silica microspheres with perovskite to form whispering gallery mode optical cavities and achieve lasing.

  14. A Review of ABO3 Perovskite Photocatalysts for Water Splitting

    Institute of Scientific and Technical Information of China (English)

    Zhang Hongjie; Chen Gang; Li Zhonghua; Liu Jiangwen

    2007-01-01

    Photocatalysts with perovskites for hydrogen production from aqueous solution were reviewed. Among the most of metal oxide photocatalysts, the family of ABO3 Perovskite-type oxide shows higher photocatalytie activity, especially alkaline earth titanate and alkali tantalate. Therein, sodium tantalate showed the highest activity for water splitting. The reasons for the high photocatalytic activity of ABO3 perovskties are considered to the diverse and flexible crystal structure. The photocatalytic activity of ABO3 perovskties can be improved by doping other element at A site, B site or O site and loading CO-catalysts such as NiO and Pt. In this paper, the mechanism of photocatalytic water splitting, the structure of ABO3 perovsktie, and Perovskite-type photocatalysts were reviewed.

  15. Transparent conducting oxide free backside illuminated perovskite solar cells

    Science.gov (United States)

    Li, Jia; Yao, Jiexiong; Xia, Huarong; Sun, Wentao; Liu, Jian; Peng, Lianmao

    2015-07-01

    Recently, hybrid perovskites have attracted great attention because of their promising applications in solar cells. However, perovskite solar devices reported till now are mostly based on transparent conducting oxide (TCO) substrates which account for a large proportion in the total cost. Herein, TCO-free perovskite solar cells are fabricated. A photo-electricity conversion efficiency of 5.27% is obtained with short circuit current density (Jsc) of 10.7 mA/cm2, open circuit voltage (Voc) of 0.837 V, and fill factor of 0.588. This study points a feasible way of replacing TCO substrate by low cost substrates, indicating promising potentials in solar energy conversion applications.

  16. A polymer scaffold for self-healing perovskite solar cells

    Science.gov (United States)

    Zhao, Yicheng; Wei, Jing; Li, Heng; Yan, Yin; Zhou, Wenke; Yu, Dapeng; Zhao, Qing

    2016-01-01

    Advancing of the lead halide perovskite solar cells towards photovoltaic market demands large-scale devices of high-power conversion efficiency, high reproducibility and stability via low-cost fabrication technology, and in particular resistance to humid environment for long-time operation. Here we achieve uniform perovskite film based on a novel polymer-scaffold architecture via a mild-temperature process. These solar cells exhibit efficiency of up to ~16% with small variation. The unencapsulated devices retain high output for up to 300 h in highly humid environment (70% relative humidity). Moreover, they show strong humidity resistant and self-healing behaviour, recovering rapidly after removing from water vapour. Not only the film can self-heal in this case, but the corresponding devices can present power conversion efficiency recovery after the water vapour is removed. Our work demonstrates the value of cheap, long chain and hygroscopic polymer scaffold in perovskite solar cells towards commercialization.

  17. Synthesis and structure of perovskite ScMnO3.

    Science.gov (United States)

    Chen, Haiyan; Yu, Tian; Gao, Peng; Bai, Jianming; Tao, Jing; Tyson, Trevor A; Wang, Liping; Lalancette, Roger

    2013-08-19

    The rare-earth manganites RMnO3 (R = rare earth) are a class of important multiferroics with stable hexagonal structures for small R ion radius (Sc, Lu, Yb, ...). Metastable perovskite phases of these systems possess intriguing electronically driven electrical polarization, but the synthesis of the perovskite phase for the end member ScMnO3 system has proven to be elusive. We report the structure of a new monoclinic P2(1)/n perovskite phase of ScMnO3 synthesized from the hexagonal phase under high-pressure and high-temperature conditions. This extends the small ion region for so-called E-phase electronically driven ferroelectric manganese perovsites.

  18. Spatially resolved optoelectronic characterization of perovskite lead iodide nanostructures

    Science.gov (United States)

    Xiao, Rui; Peng, Xingyu; Hou, Yasen; Yu, Dong

    The high power conversion efficiency of organo-lead halide perovskite-based solar cells has attracted world-wide attention over the past few years. The high efficiency was believed to originate from the unusual properties including long carrier lifetimes and consequent long carrier diffusion lengths in these materials. Ion drift, ferroelectricity, and charge traps have been proposed to account for the efficient charge separation and photocurrent hysteresis. However, it remains unclear which mechanism is dominating. We fabricate field effect transistors (FETs) incorporating single nanoplates/nanowires of organic perovskite and perform scanning photocurrent microscopic (SPCM) measurements to extract carrier diffusion lengths as a function of gate voltage, source-drain bias. Spatially resolved optoelectronic investigations of single crystalline perovskite nanostructures provide valuable information and key evidence on distinguishing the dominating charge transport/separation mechanism.

  19. Exciton localization in solution-processed organolead trihalide perovskites

    Science.gov (United States)

    He, Haiping; Yu, Qianqian; Li, Hui; Li, Jing; Si, Junjie; Jin, Yizheng; Wang, Nana; Wang, Jianpu; He, Jingwen; Wang, Xinke; Zhang, Yan; Ye, Zhizhen

    2016-03-01

    Organolead trihalide perovskites have attracted great attention due to the stunning advances in both photovoltaic and light-emitting devices. However, the photophysical properties, especially the recombination dynamics of photogenerated carriers, of this class of materials are controversial. Here we report that under an excitation level close to the working regime of solar cells, the recombination of photogenerated carriers in solution-processed methylammonium-lead-halide films is dominated by excitons weakly localized in band tail states. This scenario is evidenced by experiments of spectral-dependent luminescence decay, excitation density-dependent luminescence and frequency-dependent terahertz photoconductivity. The exciton localization effect is found to be general for several solution-processed hybrid perovskite films prepared by different methods. Our results provide insights into the charge transport and recombination mechanism in perovskite films and help to unravel their potential for high-performance optoelectronic devices.

  20. Ultrasmooth Perovskite Film via Mixed Anti-Solvent Strategy with Improved Efficiency.

    Science.gov (United States)

    Yu, Yu; Yang, Songwang; Lei, Lei; Cao, Qipeng; Shao, Jun; Zhang, Sheng; Liu, Yan

    2017-02-01

    Most antisolvents employed in previous research were miscible with perovskite precursor solution. They always led to fast formation of perovskite even if the intermediate stage existed, which was not beneficial to obtain high quality perovskite films and made the formation process less controllable. In this work, a novel ethyl ether/n-hexane mixed antisolvent (MAS) was used to achieve high nucleation density and slow down the formation process of perovskite, producing films with improved orientation of grains and ultrasmooth surfaces. These high quality films exhibited efficient charge transport at the interface of perovskite/hole transport material and perovskite solar cells based on these films showed greatly improved performance with the best power conversion efficiency of 17.08%. This work also proposed a selection principle of MAS and showed that solvent engineering by designing the mixed antisolvent system can lead to the fabrication of high-performance perovskite solar cells.

  1. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells.

    Science.gov (United States)

    Brinkmann, K O; Zhao, J; Pourdavoud, N; Becker, T; Hu, T; Olthof, S; Meerholz, K; Hoffmann, L; Gahlmann, T; Heiderhoff, R; Oszajca, M F; Luechinger, N A; Rogalla, D; Chen, Y; Cheng, B; Riedl, T

    2017-01-09

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and-more importantly-it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.

  2. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells

    Science.gov (United States)

    Brinkmann, K.O.; Zhao, J.; Pourdavoud, N.; Becker, T.; Hu, T.; Olthof, S.; Meerholz, K.; Hoffmann, L.; Gahlmann, T.; Heiderhoff, R.; Oszajca, M. F.; Luechinger, N. A.; Rogalla, D.; Chen, Y.; Cheng, B.; Riedl, T

    2017-01-01

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and—more importantly—it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability. PMID:28067308

  3. 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...

  4. Suppressed decomposition of organometal halide perovskites by impermeable electron-extraction layers in inverted solar cells

    Science.gov (United States)

    Brinkmann, K. O.; Zhao, J.; Pourdavoud, N.; Becker, T.; Hu, T.; Olthof, S.; Meerholz, K.; Hoffmann, L.; Gahlmann, T.; Heiderhoff, R.; Oszajca, M. F.; Luechinger, N. A.; Rogalla, D.; Chen, Y.; Cheng, B.; Riedl, T.

    2017-01-01

    The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and--more importantly--it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.

  5. Pin-Hole Free Perovskite Film for Solar Cells Application Prepared by Controlled Two-Step Spin-Coating Method

    Science.gov (United States)

    Bahtiar, A.; Rahmanita, S.; Inayatie, Y. D.

    2017-05-01

    Morphology of perovskite film is a key important for achieving high performance perovskite solar cells. Perovskite films are commonly prepared by two-step spin-coating method. However, pin-holes are frequently formed in perovskite films due to incomplete conversion of lead-iodide (PbI2) into perovskite CH3NH3PbI3. Pin-holes in perovskite film cause large hysteresis in current-voltage curve of solar cells due to large series resistance between perovskite layer-hole transport material. Moreover, crystal structure and grain size of perovskite crystal are also other important parameters for achieving high performance solar cells, which are significantly affected by preparation of perovskite film. We studied the effect of preparation of perovskite film using controlled spin-coating parameters on crystal structure and morphological properties of perovskite film. We used two-step spin-coating method for preparation of perovskite film with varied spinning speed, spinning time and temperature of spin-coating process to control growth of perovskite crystal aimed to produce high quality perovskite crystal with pin-hole free and large grain size. All experiment was performed in air with high humidity (larger than 80%). The best crystal structure, pin-hole free with large grain crystal size of perovskite film was obtained from film prepared at room temperature with spinning speed 1000 rpm for 20 seconds and annealed at 100°C for 300 seconds.

  6. Perovskite Solar Cells: Potentials, Challenges, and Opportunities

    Directory of Open Access Journals (Sweden)

    Muhammad Imran Ahmed

    2015-01-01

    Full Text Available Heralded as a major scientific breakthrough of 2013, organic/inorganic lead halide perovskite solar cells have ushered in a new era of renewed efforts at increasing the efficiency and lowering the cost of solar energy. As a potential game changer in the mix of technologies for alternate energy, it has emerged from a modest beginning in 2012 to efficiencies being claimed at 20.1% in a span of just two years. This remarkable progress, encouraging at one end, also points to the possibility that the potential may still be far from being fully realized. With greater insight into the photophysics involved and optimization of materials and methods, this technology stands to match or even exceed the efficiencies for single crystal silicon solar cells. With thin film solution processability, applicability to flexible substrates, and being free of liquid electrolyte, this technology combines the benefits of Dye Sensitized Solar Cells (DSSCs, Organic Photovoltaics (OPVs, and thin film solar cells. In this review we present a brief historic perspective to this development, take a cognizance of the current state of the art, and highlight challenges and the opportunities.

  7. Bright light-emitting diodes based on organometal halide perovskite.

    Science.gov (United States)

    Tan, Zhi-Kuang; Moghaddam, Reza Saberi; Lai, May Ling; Docampo, Pablo; Higler, Ruben; Deschler, Felix; Price, Michael; Sadhanala, Aditya; Pazos, Luis M; Credgington, Dan; Hanusch, Fabian; Bein, Thomas; Snaith, Henry J; Friend, Richard H

    2014-09-01

    Solid-state light-emitting devices based on direct-bandgap semiconductors have, over the past two decades, been utilized as energy-efficient sources of lighting. However, fabrication of these devices typically relies on expensive high-temperature and high-vacuum processes, rendering them uneconomical for use in large-area displays. Here, we report high-brightness light-emitting diodes based on solution-processed organometal halide perovskites. We demonstrate electroluminescence in the near-infrared, green and red by tuning the halide compositions in the perovskite. In our infrared device, a thin 15 nm layer of CH3NH3PbI(3-x)Cl(x) perovskite emitter is sandwiched between larger-bandgap titanium dioxide (TiO2) and poly(9,9'-dioctylfluorene) (F8) layers, effectively confining electrons and holes in the perovskite layer for radiative recombination. We report an infrared radiance of 13.2 W sr(-1) m(-2) at a current density of 363 mA cm(-2), with highest external and internal quantum efficiencies of 0.76% and 3.4%, respectively. In our green light-emitting device with an ITO/PEDOT:PSS/CH3NH3PbBr3/F8/Ca/Ag structure, we achieved a luminance of 364 cd m(-2) at a current density of 123 mA cm(-2), giving external and internal quantum efficiencies of 0.1% and 0.4%, respectively. We show, using photoluminescence studies, that radiative bimolecular recombination is dominant at higher excitation densities. Hence, the quantum efficiencies of the perovskite light-emitting diodes increase at higher current densities. This demonstration of effective perovskite electroluminescence offers scope for developing this unique class of materials into efficient and colour-tunable light emitters for low-cost display, lighting and optical communication applications.

  8. Garden-like perovskite superstructures with enhanced photocatalytic activity.

    Science.gov (United States)

    Ye, Meidan; Wang, Mengye; Zheng, Dajiang; Zhang, Nan; Lin, Changjian; Lin, Zhiqun

    2014-04-07

    By subjecting amorphous flower-like TiO2 to a facile hydrothermal synthesis in the presence of Sr(2+), garden-like perovskite SrTiO3 superstructures were achieved. The amorphous TiO2 was preformed using ZnO flowers as templates. Different three-dimensional SrTiO3 architectures were coexisted in the garden, including SrTiO3 flowers composed of several hollow sword-shaped petals, many sheet-shaped petals or numerous flake-shaped petals, and SrTiO3 grass consisting of a number of long blades. These SrTiO3 superstructures were simultaneously grown on fluorine-doped tin oxide (FTO) substrates. On the basis of a comprehensive study on the effects of growth time, temperature, initial concentrations of precursor, and pH, the formation of these various hierarchical architectures was attributed primarily to the dissolution of amorphous TiO2 and precipitation of perovskite crystals, followed by the Ostwald ripening process of perovskite nanocrystals and self-organization of perovskite building blocks. Interestingly, this approach can be readily extended to create other perovskite structures, including dendritic BaTiO3 and nest-like CaTiO3, as well as PbTiO3 transformed from plate-like pyrochlore Pb2Ti2O6 after post-thermal treatment. Garden-like SrTiO3 superstructures showed a superior photocatalytic performance when compared to other as-prepared semiconductors and perovskite materials (i.e., ZnO, TiO2, BaTiO3, CaTiO3 and PbTiO3), probably due to their intrinsic photocatalytic activity and special garden-like features with a coexistence of various structures that significantly facilitated the adsorption and diffusion of methyl blue (MB) molecules and oxygen species in the photochemical reaction of MB degradation.

  9. 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.

  10. Multifunctional Fullerene Derivative for Interface Engineering in Perovskite Solar Cells.

    Science.gov (United States)

    Li, Yaowen; Zhao, Yue; Chen, Qi; Yang, Yang Michael; Liu, Yongsheng; Hong, Ziruo; Liu, Zonghao; Hsieh, Yao-Tsung; Meng, Lei; Li, Yongfang; Yang, Yang

    2015-12-16

    In perovskite based planar heterojunction solar cells, the interface between the TiO2 compact layer and the perovskite film is critical for high photovoltaic performance. The deep trap states on the TiO2 surface induce several challenging issues, such as charge recombination loss and poor stability etc. To solve the problems, we synthesized a triblock fullerene derivative (PCBB-2CN-2C8) via rational molecular design for interface engineering in the perovskite solar cells. Modifying the TiO2 surface with the compound significantly improves charge extraction from the perovskite layer. Together with its uplifted surface work function, open circuit voltage and fill factor are dramatically increased from 0.99 to 1.06 V, and from 72.2% to 79.1%, respectively, resulting in 20.7% improvement in power conversion efficiency for the best performing devices. Scrutinizing the electrical properties of this modified interfacial layer strongly suggests that PCBB-2CN-2C8 passivates the TiO2 surface and thus reduces charge recombination loss caused by the deep trap states of TiO2. The passivation effect is further proven by stability testing of the perovskite solar cells with shelf lifetime under ambient conditions improved by a factor of more than 4, from ∼40 h to ∼200 h, using PCBB-2CN-2C8 as the TiO2 modification layer. This work offers not only a promising material for cathode interface engineering, but also provides a viable approach to address the challenges of deep trap states on TiO2 surface in planar perovskite solar cells.

  11. 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.

  12. Pathways toward high-performance perovskite solar cells: review of recent advances in organo-metal halide perovskites for photovoltaic applications

    Science.gov (United States)

    Song, Zhaoning; Watthage, Suneth C.; Phillips, Adam B.; Heben, Michael J.

    2016-04-01

    Organo-metal halide perovskite-based solar cells have been the focus of intense research over the past five years, and power conversion efficiencies have rapidly been improved from 3.8 to >21%. This article reviews major advances in perovskite solar cells that have contributed to the recent efficiency enhancements, including the evolution of device architecture, the development of material deposition processes, and the advanced device engineering techniques aiming to improve control over morphology, crystallinity, composition, and the interface properties of the perovskite thin films. The challenges and future directions for perovskite solar cell research and development are also discussed.

  13. Navigating Organo-Lead Halide Perovskite Phase Space via Nucleation Kinetics toward a Deeper Understanding of Perovskite Phase Transformations and Structure-Property Relationships.

    Science.gov (United States)

    Williams, Spencer T; Chueh, Chu-Chen; Jen, Alex K-Y

    2015-07-01

    Organo-lead halide perovskite photovoltaics have developed faster than our understanding of the material itself. Using the vast body of work on perovskite processing created in just the past few years, it is possible to create a better picture of this material's complex phase-transformation behavior. This concept paper summarizes and correlates the current understanding of structural intermediates, kinetic controls, and structure-property relationships of organo-lead iodide perovskites. To this end, a new way of graphically relating information is developed, allowing the simultaneous mapping of schematic kinetic relationships between all currently prevailing perovskite deposition and growth techniques.

  14. Methods for producing single crystal mixed halide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Kai; Zhao, Yixin

    2017-07-11

    An aspect of the present invention is a method that includes contacting a metal halide and a first alkylammonium halide in a solvent to form a solution and maintaining the solution at a first temperature, resulting in the formation of at least one alkylammonium halide perovskite crystal, where the metal halide includes a first halogen and a metal, the first alkylammonium halide includes the first halogen, the at least one alkylammonium halide perovskite crystal includes the metal and the first halogen, and the first temperature is above about 21.degree. C.

  15. 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

  16. Theoretical insights into multibandgap hybrid perovskites for photovoltaic applications

    OpenAIRE

    Even, Jacky; Sapori, Daniel; Pedesseau, Laurent; Rolland, Alain; Kepenekian, Mikael; Robles, Roberto; Wang, Shijian; Huang, Yong; Beck, Alexandre; Durand, Olivier; Katan, Claudine

    2015-01-01

    International audience; This paper reviews some of the recent theoretical investigations on the Rashba Dresselhaus spin effects and dielectric properties of CH 3 NH 3 PbI 3 hybrid perovskites and CsPbI 3 all-inorganic perovskites using Density functional theory. The spin vectors rotate in the non-centrosymmetric P4mm tetragonal phase, respectively clockwise and counterclockwise, in a manner that is characteristic of a pure Rashba effect. The high frequency dielectric constants ε ∞ of MAPbI 3 ...

  17. Ab initio study of proton dynamics on perovskite oxide surfaces

    Directory of Open Access Journals (Sweden)

    Fuyuki Shimojo

    2007-01-01

    Full Text Available First-principles studies of the proton dynamics in perovskite oxides and the water adsorption on various oxide surfaces are briefly reviewed. Recent progress in the study of the microscopic mechanism of the proton absorption from perovskite oxide surfaces is also presented. It is shown that dopant ions on the surface and oxygen vacancies in the inside just below the surface play an important role for the proton absorption, while oxygen vacancies on the surface are influential for the dissociative adsorption of water molecules.

  18. n-Pentylamine-intercalated layered perovskite-type oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel n-pentylamine-intercalated layered perovskite-type oxide,C5H11NH3-Sr2Nb3O10, was prepared and characterized by using XRD, FT-IR, Raman spectrascopy, and elemental analysis. It was shown that the intercalated n-pentylamine adopted a bilayer formation with some overlap and tilt, and the lattice of the perovskite layer was distorted due to the intercalation of n-pentylamine. The as-prepared sample gave clear electric hysteresis loop and did not show fatigue after 1011 switching circles, and therefore, could be considered as a new kind of fatigue-free ferroelectric materials.

  19. High Temperature LFMR in Yttrium Doped Perovskite Manganites

    Institute of Scientific and Technical Information of China (English)

    盛晓波; 童林夙; 林萍华; 杨石强; 储成林; 翟亚

    2003-01-01

    Porous ceramic samples of Y doped perovskite manganites were prepared. In these samples, the transition from high temperature paramagnetic insulator to low temperature ferromagnetic metal as well as the low field magnetoresistance (LFMR) effect at the low temperature is similar to that in dense samples. Opposite to that in dense samples, LFMR effect in porous sample is observed at the high temperature close to the peak of MR-T curves. The results suggest that the high temperature LFMR effect and the applicable colossal magnetoresistance (CMR) materials could be obtained by controlling the microstructures of this class of perovskite manganites.

  20. A bifunctional perovskite catalyst for oxygen reduction and evolution.

    Science.gov (United States)

    Jung, Jae-Il; Jeong, Hu Young; Lee, Jang-Soo; Kim, Min Gyu; Cho, Jaephil

    2014-04-25

    La0.3(Ba0.5Sr0.5)0.7Co0.8Fe0.2O3d is a promising bifunctional perovskite catalyst for the oxygen reduction reaction and the oxygen evolution reaction. This catalyst has circa 10 nm-scale rhombohedral LaCoO3 cobaltite particles distributed on the surface. The dynamic microstructure phenomena are attributed to the charge imbalance from the replacement of A-site cations with La3+ and local stress on Cosite sub-lattice with the cubic perovskite structure.

  1. Random lasing in organo-lead halide perovskite microcrystal networks

    Science.gov (United States)

    Dhanker, R.; Brigeman, A. N.; Larsen, A. V.; Stewart, R. J.; Asbury, J. B.; Giebink, N. C.

    2014-10-01

    We report optically pumped random lasing in planar methylammonium lead iodide perovskite microcrystal networks that form spontaneously from spin coating. Low thresholds (100 μm and spatially overlap with one another, resulting in chaotic pulse-to-pulse intensity fluctuations due to gain competition. These results demonstrate this class of hybrid organic-inorganic perovskite as a platform to study random lasing with well-defined, low-level disorder, and support the potential of these materials for use in semiconductor laser applications.

  2. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-04-01

    With the soaring advancement of organolead halide perovskite solar cells rising from a power conversion efficiency of merely 3% to more than 22% shortly in five years, researchers’ interests on this big material family have been greatly spurred. So far, both in-depth studies on the fundamental properties of organolead halide perovskites and their extended applications such as photodetectors, light emitting diodes, and lasing have been intensively reported. The great successes have been ascribed to various superior properties of organolead halide hybrid perovskites such as long carrier lifetimes, high carrier mobility, and solution-processable high quality thin films, as will be discussed in Chapter 1. Notably, most of these studies have been limited to their polycrystalline thin films. Single crystals, as a counter form of polycrystals, have no grain boundaries and higher crystallinity, and thus less defects. These characteristics gift single crystals with superior optical, electrical, and mechanical properties, which will be discussed in Chapter 2. For example, organolead halide perovskite single crystals have been reported with much longer carrier lifetimes and higher carrier mobilities, which are especially intriguing for optoelectronic applications. Besides their superior optoelectronic properties, organolead halide perovskites have shown large composition versatility, especially their organic components, which can be controlled to effectively adjust their crystal structures and further fundamental properties. Single crystals are an ideal platform for such composition-structure-property study since a uniform structure with homogeneous compositions and without distraction from grain boundaries as well as excess defects can provide unambiguously information of material properties. As a major part of work of this dissertation, explorative work on the composition-structure-property study of organic-cation-alloyed organolead halide perovskites using their single

  3. The physics of photon induced degradation of perovskite solar cells

    Science.gov (United States)

    Joshi, Pranav H.; Zhang, Liang; Hossain, Istiaque M.; Abbas, Hisham A.; Kottokkaran, Ranjith; Nehra, Satyapal P.; Dhaka, Mahendra; Noack, Max; Dalal, Vikram L.

    2016-11-01

    Lead-trihalide perovskite solar cells are an important photovoltaic technology. We investigate the effect of light induced degradation on perovskite solar cells. During exposure, the open-circuit voltage (Voc) of the device increases, whereas the short-circuit current (Isc) shows a decrease. The degradation can be completely recovered using thermal annealing in dark. We develop a model based on light induced generation of ions and migration of these ions inside the material to explain the changes in Isc, Voc, capacitance and dark current upon light exposure and post-exposure recovery. There was no change in defect density in the material upon exposure.

  4. Vibrational spectroscopy on protons and deuterons in proton conducting perovskites

    DEFF Research Database (Denmark)

    Glerup, M.; Poulsen, F.W.; Berg, R.W.

    2002-01-01

    A short review of IR-spectroscopy on protons in perovskite structure oxides is given. The nature of possible proton sites, libration and combination tones and degree of hydrogen bonding is emphasised. Three new spectroscopic experiments and/or interpretations are presented. An IR-microscopy exper......A short review of IR-spectroscopy on protons in perovskite structure oxides is given. The nature of possible proton sites, libration and combination tones and degree of hydrogen bonding is emphasised. Three new spectroscopic experiments and/or interpretations are presented. An IR...

  5. The physics of photon induced degradation of perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Pranav H. Joshi

    2016-11-01

    Full Text Available Lead-trihalide perovskite solar cells are an important photovoltaic technology. We investigate the effect of light induced degradation on perovskite solar cells. During exposure, the open-circuit voltage (Voc of the device increases, whereas the short-circuit current (Isc shows a decrease. The degradation can be completely recovered using thermal annealing in dark. We develop a model based on light induced generation of ions and migration of these ions inside the material to explain the changes in Isc, Voc, capacitance and dark current upon light exposure and post-exposure recovery. There was no change in defect density in the material upon exposure.

  6. Phase transitions and compressibility of NaMgF3 (Neighborite) in perovskite- and post-perovskite-related structures

    Science.gov (United States)

    Martin, C. David; Crichton, Wilson A.; Liu, Haozhe; Prakapenka, Vitali; Chen, Jiuhua; Parise, John B.

    2006-06-01

    Monochromatic x-ray diffraction data collected in-situ within the diamond anvil cell show perovskite structured Neighborite (NaMgF3) transforms to the CaIrO3-type post-perovskite structure between 28 and 30 GPa. Upon laser heating, the CaIrO3-type structure transforms further to an unknown structure (Pnnm, designated N-phase). Upon pressure release, N-phase NaMgF3 becomes x-ray amorphous. A structure transformation in post-perovskite MgSiO3 and MgGeO3 to N-phase may account for previous observations of extra x-ray reflections during high pressure experiments and tomographic observations of an additional boundary in the lower mantle below the D'' discontinuity.

  7. Lattice thermal conductivity of MgSiO3 perovskite and post-perovskite at the core-mantle boundary

    Science.gov (United States)

    Ohta, K.; Yagi, T.; Taketoshi, N.; Hirose, K.; Komabayashi, T.; Baba, T.; Ohishi, Y.; Hernlund, J. W.

    2011-12-01

    Heat in the Earth's interior is transported dominantly by convection in the mantle and core, and by conduction at thermal boundary layers. The thermal conductivity of the bottom thermal boundary layer of the mantle determines the magnitude of heat flux from the core, and is intimately related to the formation of mantle plumes, the long-term thermal evolution of both mantle and core, and the driving force for generation of the geomagnetic field (Lay et al. 2008). However, the thermal conductivity and diffusivity have been poorly constrained at the high pressures of Earth's lowermost mantle. Previous estimates of the thermal conductivity in this region ranged widely between 5 and 30 W/m/K, and it has been often assumed to be 10 W/m/K (Lay et al. 2006). The lattice thermal diffusivity of MgSiO3 perovskite, a primary mineral in the Earth's lower mantle, has only been measured at 1 bar (Osako and Ito 1991). And the thermal diffusivity of post-perovskite has not been investigated so far. We measured the lattice component of thermal diffusivities of both MgSiO3 perovskite and post-perovskite to 144 GPa using a light pulse thermoreflectance technique in a diamond anvil cell (Yagi et al. 2011). The estimated lattice thermal conductivity of perovskite-dominant lowermost mantle is about 9 W/m/K, while post-perovskite-dominant one exhibits ~50% higher diffusivity than perovskite at equivalent pressure. Since many previous calculations assumed a lowermost mantle conductivity of 10 W/m/K, compatible with values obtained in this study, the present findings do not significantly alter the magnitude of heat flow from the core estimated using the post-perovskite double-crossing model (e.g., Lay et al. 2006). Indeed, the present results continue to support the notion of high core-mantle boundary heat flow along with a large degree of secular cooling necessary to sustain a geodynamo even in the absence of an inner core.

  8. Electrical conductivity of (Mg,Fe)SiO3 Perovskite and a Perovskite-dominated assemblage at lower mantle conditions

    Science.gov (United States)

    Li, Xiaoyuan; Jeanloz, Raymond

    1987-01-01

    Electrical conductivity measurements of Perovskite and a Perovskite-dominated assemblage synthesized from pyroxene and olivine demonstrate that these high-pressure phases are insulating to pressures of 82 GPa and temperatures of 4500 K. Assuming an anhydrous upper mantle composition, the result provides an upper bound of 0.01 S/m for the electrical conductivity of the lower mantle between depths of 700 and 1900 km. This is 2 to 4 orders of magnitude lower than previous estimates of lower-mantle conductivity derived from studies of geomagnetic secular variations.

  9. Orbital physics in the perovskite Ti oxides

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Masahito [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Imada, Masatoshi [Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2004-11-01

    Titanate compounds have been recognized as key materials for understanding the coupling of magnetism and orbitals in strongly correlated electron systems. In the perovskite Ti oxide RTiO{sub 3} (where R represents the trivalent rare-earth ions), which is a typical Mott-Hubbard insulator, the Ti t{sub 2g} orbitals and spins in the 3d{sup 1} state couple each other through the strong electron correlations, resulting in a rich variety of orbital-spin phases. One way of controlling the coupling is to change the tiltings of the TiO{sub 6} octahedra (namely the GdFeO{sub 3}-type distortion) by varying the R ions, through which the relative ratio of the electron bandwidth to the Coulomb interaction is controlled. With this control, these Mott insulators exhibit an antiferromagnetic-to-ferromagnetic (AFM-FM) phase transition, which has turned out to be a consequence of rich orbital physics in these materials. The origin and nature of orbital-spin structures of these Mott insulators have been intensively studied both experimentally and theoretically. When the Mott insulators are doped with carriers, the titanates show touchstone properties of the filling controlled Mott transition. In this paper, we first review the state of the art on the studies for understanding physics contained in the properties of the perovskite titanates. On the properties of the insulators, we focus on the following three topics: (1) the origin and nature of the ferromagnetism as well as the orbital ordering in the compounds with relatively small R ions such as GdTiO{sub 3} and YTiO{sub 3} (2) the origin of the G-type antiferromagnetism and the orbital state in LaTiO{sub 3} and (3) the orbital-spin structures in other AFM(G) compounds with relatively large R ions (R = Ce, Pr, Nd and Sm). On the basis of these discussions, we discuss the whole phase diagram together with mechanisms of the magnetic phase transition. On the basis of the microscopic understanding of the orbital-spin states, we show that

  10. Progress on lead-free metal halide perovskites for photovoltaic applications: a review.

    Science.gov (United States)

    Hoefler, Sebastian F; Trimmel, Gregor; Rath, Thomas

    2017-01-01

    Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties.

  11. Evaluating the Optoelectronic Quality of Hybrid Perovskites by Conductive Atomic Force Microscopy with Noise Spectroscopy.

    Science.gov (United States)

    Lee, Byungho; Lee, Sangheon; Cho, Duckhyung; Kim, Jinhyun; Hwang, Taehyun; Kim, Kyung Hwan; Hong, Seunghun; Moon, Taeho; Park, Byungwoo

    2016-11-16

    Organic-inorganic hybrid perovskite solar cells have emerged as promising candidates for next-generation solar cells. To attain high photovoltaic efficiency, reducing the defects in perovskites is crucial along with a uniform coating of the films. Also, evaluating the quality of synthesized perovskites via facile and adequate methods is important as well. Herein, CH3NH3PbI3 perovskites were synthesized by applying second solvent dripping to nonstoichiometric precursors containing excess CH3NH3I. The resulting perovskite films exhibited a larger average grain size with a better crystallinity compared to that from stoichiometric precursors. As a result, the performance of planar perovskite solar cells was significantly improved, achieving an efficiency of 14.3%. Furthermore, perovskite films were effectively analyzed using a conductive AFM and noise spectroscopy, which have been uncommon in the field of perovskite solar cells. Comparing the topography and photocurrent maps, the variation of photocurrents in nanoscale was systematically investigated, and a linear relationship between the grain size and photocurrent was revealed. Also, noise analyses with a conductive probe enabled examination of the defect density of perovskites at specific grain interiors by excluding the grain-boundary effect, and reduced defects were clearly observed for the perovskites using CH3NH3I-rich precursors.

  12. Enhancement of Exciton Emission in Lead Halide-Based Layered Perovskites by Cation Mixing.

    Science.gov (United States)

    Era, Masanao; Komatsu, Yumeko; Sakamoto, Naotaka

    2016-04-01

    Spin-coated films of a lead halide, PbX: X = I and Br, layered perovskites having cyclohexenylethyl ammonium molecule as an organic layer, which were mixed with other metal halide-based layered perovskites consisting of various divalent metal halides (for example, Ca2, Cdl2, FeI2, SnBr2 and so on), were prepared. The results of X-ray diffraction measurements exhibited that solid solution formation between PbX-based layered perovskite and other divalent metal halide-based layered perovskites was observed up to very high molar concentration of 50 molar% in the mixed film samples when divalent cations having ionic radius close to that of Pb2+ were employed. In the solid solution films, the exciton emission was much enhanced at room temperature. Exciton emission intensity of Pbl-based layered perovskite mixed with Cal-based layered perovskite (20 molar%) is about 5 times large that of the pristine Pbl-based layered perovskite, and that of PbBr-based layered perovskite mixed with SnBr-based layered perovskite (20 molar%) was also about 5 times large that of the pristine PbBr-based layered perovskite at room temperature.

  13. Oxide perovskite crystals for HTSC film substrates microwave applications

    Science.gov (United States)

    Bhalla, A. S.; Guo, Ruyan

    1995-01-01

    The research focused upon generating new substrate materials for the deposition of superconducting yttrium barium cuprate (YBCO) has yielded several new hosts in complex perovskites, modified perovskites, and other structure families. New substrate candidates such as Sr(Al(1/2)Ta(1/2))O3 and Sr(Al(1/2)Nb(1/2))O3, Ba(Mg(1/3)Ta(2/3))O3 in complex oxide perovskite structure family and their solid solutions with ternary perovskite LaAlO3 and NdGaO3 are reported. Conventional ceramic processing techniques were used to fabricate dense ceramic samples. A laser heated molten zone growth system was utilized for the test-growth of these candidate materials in single crystal fiber form to determine crystallographic structure, melting point, thermal, and dielectric properties as well as to make positive identification of twin free systems. Some of those candidate materials present an excellent combination of properties suitable for microwave HTSC substrate applications.

  14. High-performance perovskite-graphene hybrid photodetector.

    Science.gov (United States)

    Lee, Youngbin; Kwon, Jeong; Hwang, Euyheon; Ra, Chang-Ho; Yoo, Won Jong; Ahn, Jong-Hyun; Park, Jong Hyeok; Cho, Jeong Ho

    2015-01-01

    A high-performance novel photodetector is demonstrated, which consists of graphene and CH3 NH3 PbI3 perovskite layers. The resulting hybrid photodetector exhibits a dramatically enhanced photo responsivity (180 A/W) and effective quantum efficiency (5× 10(4) %) over a broad bandwidth within the UV and visible ranges.

  15. Materials Processing Routes to Trap-Free Halide Perovskites

    KAUST Repository

    Buin, Andrei

    2014-11-12

    © 2014 American Chemical Society. Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently achieving an impressive 17.9% certified solar power conversion efficiency. Reports have consistently emphasized that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films grown under iodine-rich conditions are prone to a high density of deep electronic traps (recombination centers), while the use of a chloride precursor avoids the formation of key defects (Pb atom substituted by I) responsible for short diffusion lengths and poor photovoltaic performance. Furthermore, the lowest-energy surfaces of perovskite crystals are found to be entirely trap-free, preserving both electron and hole delocalization to a remarkable degree, helping to account for explaining the success of polycrystalline perovskite films. We construct perovskite films from I-poor conditions using a lead acetate precursor, and our measurement of a long (600 ± 40 nm) diffusion length confirms this new picture of the importance of growth conditions.

  16. Tuning Ferromagnetism at Interfaces between Insulating Perovskite Oxides

    NARCIS (Netherlands)

    Ganguli, Nirmal; Kelly, Paul J.

    2014-01-01

    We use density functional theory calculations to show that the LaAlO 3 |SrTiO 3 interface between insulating perovskite oxides is borderline in satisfying the Stoner criterion for itinerant ferromagnetism and explore other oxide combinations with a view to satisfying it more amply. The larger latt

  17. Controlling Octahedral Rotations in a Perovskite via Strain Doping

    Science.gov (United States)

    Herklotz, A.; Wong, A. T.; Meyer, T.; Biegalski, M. D.; Lee, H. N.; Ward, T. Z.

    2016-05-01

    The perovskite unit cell is the fundamental building block of many functional materials. The manipulation of this crystal structure is known to be of central importance to controlling many technologically promising phenomena related to superconductivity, multiferroicity, mangetoresistivity, and photovoltaics. The broad range of properties that this structure can exhibit is in part due to the centrally coordinated octahedra bond flexibility, which allows for a multitude of distortions from the ideal highly symmetric structure. However, continuous and fine manipulation of these distortions has never been possible. Here, we show that controlled insertion of He atoms into an epitaxial perovskite film can be used to finely tune the lattice symmetry by modifying the local distortions, i.e., octahedral bonding angle and length. Orthorhombic SrRuO3 films coherently grown on SrTiO3 substrates are used as a model system. Implanted He atoms are confirmed to induce out-of-plane strain, which provides the ability to controllably shift the bulk-like orthorhombically distorted phase to a tetragonal structure by shifting the oxygen octahedra rotation pattern. These results demonstrate that He implantation offers an entirely new pathway to strain engineering of perovskite-based complex oxide thin films, useful for creating new functionalities or properties in perovskite materials.

  18. Krypton irradiation damage in Nd-doped zirconolite and perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Davoisne, C. [Department of Materials, Imperial College London, London (United Kingdom); LRCS, CNRS-UMR 6007, Universite de Picardie Jules Verne, Amiens (France); Stennett, M.C.; Hyatt, N.C. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, University of Sheffield, Sheffield (United Kingdom); Peng, N.; Jeynes, C. [Ion Beam Centre, University of Surrey, Guildford (United Kingdom); Lee, W.E., E-mail: w.e.lee@imperial.ac.uk [Department of Materials, Imperial College London, London (United Kingdom)

    2011-08-01

    Understanding the effect of radiation damage and noble gas accommodation in potential ceramic hosts for plutonium disposition is necessary to evaluate their long-term behaviour during geological disposal. Polycrystalline samples of Nd-doped zirconolite and Nd-doped perovskite were irradiated ex situ with 2 MeV Kr{sup +} at a dose of 5 x 10{sup 15} ions cm{sup -2} to simulate recoil of Pu nuclei during alpha decay. The feasibility of thin section preparation of both pristine and irradiated samples by Focused Ion Beam sectioning was demonstrated. After irradiation, the Nd-doped zirconolite revealed a well defined amorphous region separated from the pristine material by a thin (40-60 nm) damaged interface. The zirconolite lattice was lost in the damaged interface, but the fluorite sublattice was retained. The Nd-doped perovskite contained a defined irradiated layer composed of an amorphous region surrounded by damaged but still crystalline layers. The structural evolution of the damaged regions is consistent with a change from orthorhombic to cubic symmetry. In addition in Nd-doped perovskite, the amorphisation dose depended on crystallographic orientation and possibly sample configuration (thin section or bulk). Electron Energy Loss Spectroscopy revealed Ti remained in the 4+ oxidation state but there was a change in Ti coordination in both Nd-doped perovskite and Nd-doped zirconolite associated with the crystalline to amorphous transition.

  19. X-ray Scintillation in Lead Halide Perovskite Crystals

    CERN Document Server

    Birowosuto, M D; Drozdowski, W; Brylew, K; Lachmanski, W; Bruno, A; Soci, C

    2016-01-01

    Current technologies for X-ray detection rely on scintillation from expensive inorganic crystals grown at high-temperature, which so far has hindered the development of large-area scintillator arrays. Thanks to the presence of heavy atoms, solution-grown hybrid lead halide perovskite single crystals exhibit short X-ray absorption length and excellent detection efficiency. Here we compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray excited thermoluminescence measurements indicate the absence of deep traps and a very small density of shallow trap states, which lessens after-glow effects. All perovskite single crystals exhibit high X-ray excited luminescence yields of >120,000 photons/MeV at low temperature. Although thermal quenching is significant at room temperature, the large exciton binding energy of 2D (EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites, and moderate light yie...

  20. Multifunctional MgO Layer in Perovskite Solar Cells.

    Science.gov (United States)

    Guo, Xudong; Dong, Haopeng; Li, Wenzhe; Li, Nan; Wang, Liduo

    2015-06-08

    A multifunctional magnesium oxide (MgO) layer was successfully introduced into perovskite solar cells (PSCs) to enhance their performance. MgO was coated onto the surface of mesoporous TiO(2) by the decomposition of magnesium acetate and, therefore, could block contact between the perovskite and TiO(2). X-ray photoelectron spectroscopy and infrared spectroscopy showed that the amount of H(2)O/hydroxyl absorbed on the TiO(2) decreased after MgO modification. The UV/Vis absorption spectra of the perovskite with MgO modification revealed an enhanced photoelectric performance compared with that of unmodified perovskite after UV illumination. In addition to the photocurrent, the photovoltage and fill factor also showed an enhancement after modification, which resulted in an increase in the overall efficiency of the cell from 9.6 to 13.9 %. Electrochemical impedance spectroscopy (EIS) confirmed that MgO acts as an insulating layer to reduce charge recombination.

  1. Tuning Ferromagnetism at Interfaces between Insulating Perovskite Oxides

    NARCIS (Netherlands)

    Ganguli, N.; Kelly, Paul J.

    2014-01-01

    We use density functional theory calculations to show that the LaAlO 3 |SrTiO 3 interface between insulating perovskite oxides is borderline in satisfying the Stoner criterion for itinerant ferromagnetism and explore other oxide combinations with a view to satisfying it more amply. The larger

  2. Simulation of perovskite solar cells with inorganic hole transporting materials

    DEFF Research Database (Denmark)

    Wang, Yan; Xia, Zhonggao; Liu, Yiming

    2015-01-01

    Device modeling organolead halide perovskite solar cells with planar architecture based on inorganic hole transporting materials (HTMs) were performed. A thorough understanding of the role of the inorganic HTMs and the effect of band offset between HTM/absorber layers is indispensable for further...

  3. The nature of domain stabilization in ferroelectric perovskites

    NARCIS (Netherlands)

    Lambeck, Paul; Jonker, G.H.

    1986-01-01

    Ferroelectric perovskites, such as Pb(Ti,Zr)O3 and BaTiO3, are subject to ageing effects, caused by a gradual stabilization of the ferroelectric domain structure. We studied the development of this stabilization in Mn-doped BaTiO3 monocrystals having a special kind of domain structure. We concluded

  4. Hysteresis, Stability, and Ion Migration in Lead Halide Perovskite Photovoltaics.

    Science.gov (United States)

    Miyano, Kenjiro; Yanagida, Masatoshi; Tripathi, Neeti; Shirai, Yasuhiro

    2016-06-16

    Ion migration has been suspected as the origin of various irreproducible and unstable properties, most notably the hysteresis, of lead halide perovskite photovoltaic (PV) cells since the early stage of the research. Although many evidence of ionic movement have been presented both numerically and experimentally, a coherent and quantitative picture that accounts for the observed irreproducible phenomena is still lacking. At the same time, however, it has been noticed that in certain types of PV cells, the hysteresis is absent or at least within the measurement reproducibility. We have previously shown that the electronic properties of hysteresis-free cells are well represented in terms of the conventional inorganic semiconductors. The reproducibility of these measurements was confirmed typically within tens of minutes under the biasing field of -1 V to +1.5 V. In order to probe the effect of ionic motion in the hysteresis-free cells, we extended the time scale and the biasing rage in the electronic measurements, from which we conclude the following: (1) From various evidence, it appears that ion migration is inevitable. However, it does not cause detrimental effects to the PV operation. (2) We propose, based on the quantitative characterization, that the degradation is more likely due to the chemical change at the interfaces between the carrier selective layers and perovskite rather than the compositional change of the lead iodide perovskite bulk. Together, they give much hope in the use of the lead iodide perovskite in the use of actual application.

  5. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

    NARCIS (Netherlands)

    Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D.; Katan, Claudine; Even, Jacky; Kepenekian, Mikael

    2016-01-01

    Layered halide hybrid organic inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells

  6. Emission Enhancement and Intermittency in Polycrystalline Organolead Halide Perovskite Films

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2016-08-01

    Full Text Available Inorganic-organic halide organometal perovskites have demonstrated very promising performance for opto-electronic applications, such as solar cells, light-emitting diodes, lasers, single-photon sources, etc. However, the little knowledge on the underlying photophysics, especially on a microscopic scale, hampers the further improvement of devices based on this material. In this communication, correlated conventional photoluminescence (PL characterization and wide-field PL imaging as a function of time are employed to investigate the spatially- and temporally-resolved PL in CH3NH3PbI3−xClx perovskite films. Along with a continuous increase of the PL intensity during light soaking, we also observe PL blinking or PL intermittency behavior in individual grains of these films. Combined with significant suppression of PL blinking in perovskite films coated with a phenyl-C61-butyric acid methyl ester (PCBM layer, it suggests that this PL intermittency is attributed to Auger recombination induced by photoionized defects/traps or mobile ions within grains. These defects/traps are detrimental for light conversion and can be effectively passivated by the PCBM layer. This finding paves the way to provide a guideline on the further improvement of perovskite opto-electronic devices.

  7. Towards the scaling up of perovskite solar cells and modules

    NARCIS (Netherlands)

    Galagan, Y.; Coenen, E.W.C.; Verhees, W.J.H.; Andriessen, R.

    2016-01-01

    A direct current (DC) simulation for perovskite solar cells with different dimensions was performed. The theoretical results demonstrate a good agreement with experimental data, indicating the reliability of the performed simulation. A theoretical model was applied for the investigation of large are

  8. Comprehensive design of omnidirectional high-performance perovskite solar cells

    Science.gov (United States)

    Zhang, Yutao; Xuan, Yimin

    2016-01-01

    The comprehensive design approach is established with coupled optical-electrical simulation for perovskite-based solar cell, which emerged as one of the most promising competitors to silicon solar cell for its low-cost fabrication and high PCE. The selection of structured surface, effect of geometry parameters, incident angle-dependence and polarization-sensitivity are considered in the simulation. The optical modeling is performed via the finite-difference time-domain method whilst the electrical properties are obtained by solving the coupled nonlinear equations of Poisson, continuity, and drift-diffusion equations. The optical and electrical performances of five different structured surfaces are compared to select a best structured surface for perovskite solar cell. The effects of the geometry parameters on the optical and electrical properties of the perovskite cell are analyzed. The results indicate that the light harvesting is obviously enhanced by the structured surface. The electrical performance can be remarkably improved due to the enhanced light harvesting of the designed best structured surface. The angle-dependence for s- and p-polarizations is investigated. The structured surface exhibits omnidirectional behavior and favorable polarization-insensitive feature within a wide incident angle range. Such a comprehensive design approach can highlight the potential of perovskite cell for power conversion in the full daylight. PMID:27405419

  9. Towards the scaling up of perovskite solar cells and modules

    NARCIS (Netherlands)

    Galagan, Y.; Coenen, E.W.C.; Verhees, W.J.H.; Andriessen, R.

    2016-01-01

    A direct current (DC) simulation for perovskite solar cells with different dimensions was performed. The theoretical results demonstrate a good agreement with experimental data, indicating the reliability of the performed simulation. A theoretical model was applied for the investigation of large

  10. 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.

  11. Performance of genetic algorithms in search for water splitting perovskites

    DEFF Research Database (Denmark)

    Jain, A.; Castelli, Ivano Eligio; Hautier, G.

    2013-01-01

    We examine the performance of genetic algorithms (GAs) in uncovering solar water light splitters over a space of almost 19,000 perovskite materials. The entire search space was previously calculated using density functional theory to determine solutions that fulfill constraints on stability, band...

  12. Improving Perovskite Solar Cells: Insights From a Validated Device Model

    NARCIS (Netherlands)

    Sherkar, Tejas S.; Momblona, Cristina; Gil-Escrig, Lidon; Bolink, Henk J.; Koster, L. Jan Anton

    2017-01-01

    To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of conta

  13. Homogeneous porous perovskite supports for thin dense oxygen separation membranes

    NARCIS (Netherlands)

    Haar, van der L.M.; Verweij, H.

    2000-01-01

    Porous La1−xSrxCoO3−δ substrates (x=0.7, 0.5 and 0.2) were prepared as supports for thin mixed ionic-electronic conducting perovskite membranes. The preparation method is based on pyrolythic powder preparation, followed by high temperature calcination to reduce the sinter activity of the powder. Sub

  14. Towards the scaling up of perovskite solar cells and modules

    NARCIS (Netherlands)

    Galagan, Y.; Coenen, E.W.C.; Verhees, W.J.H.; Andriessen, R.

    2016-01-01

    A direct current (DC) simulation for perovskite solar cells with different dimensions was performed. The theoretical results demonstrate a good agreement with experimental data, indicating the reliability of the performed simulation. A theoretical model was applied for the investigation of large are

  15. Field-emission from quantum-dot-in-perovskite solids

    Science.gov (United States)

    García de Arquer, F. Pelayo; Gong, Xiwen; Sabatini, Randy P.; Liu, Min; Kim, Gi-Hwan; Sutherland, Brandon R.; Voznyy, Oleksandr; Xu, Jixian; Pang, Yuangjie; Hoogland, Sjoerd; Sinton, David; Sargent, Edward

    2017-03-01

    Quantum dot and well architectures are attractive for infrared optoelectronics, and have led to the realization of compelling light sensors. However, they require well-defined passivated interfaces and rapid charge transport, and this has restricted their efficient implementation to costly vacuum-epitaxially grown semiconductors. Here we report solution-processed, sensitive infrared field-emission photodetectors. Using quantum-dots-in-perovskite, we demonstrate the extraction of photocarriers via field emission, followed by the recirculation of photogenerated carriers. We use in operando ultrafast transient spectroscopy to sense bias-dependent photoemission and recapture in field-emission devices. The resultant photodiodes exploit the superior electronic transport properties of organometal halide perovskites, the quantum-size-tuned absorption of the colloidal quantum dots and their matched interface. These field-emission quantum-dot-in-perovskite photodiodes extend the perovskite response into the short-wavelength infrared and achieve measured specific detectivities that exceed 1012 Jones. The results pave the way towards novel functional photonic devices with applications in photovoltaics and light emission.

  16. A general approach for monodisperse colloidal perovskites, Chemistry of Materials

    NARCIS (Netherlands)

    Demirors, A.F.; Imhof, A.

    2009-01-01

    We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite parti

  17. Two-Dimensional Halide Perovskites: Tuning Electronic Activities of Defects.

    Science.gov (United States)

    Liu, Yuanyue; Xiao, Hai; Goddard, William A

    2016-05-11

    Two-dimensional (2D) halide perovskites are emerging as promising candidates for nanoelectronics and optoelectronics. To realize their full potential, it is important to understand the role of those defects that can strongly impact material properties. In contrast to other popular 2D semiconductors (e.g., transition metal dichalcogenides MX2) for which defects typically induce harmful traps, we show that the electronic activities of defects in 2D perovskites are significantly tunable. For example, even with a fixed lattice orientation one can change the synthesis conditions to convert a line defect (edge or grain boundary) from electron acceptor to inactive site without deep gap states. We show that this difference originates from the enhanced ionic bonding in these perovskites compared with MX2. The donors tend to have high formation energies and the harmful defects are difficult to form at a low halide chemical potential. Thus, we unveil unique properties of defects in 2D perovskites and suggest practical routes to improve them.

  18. A Monolithic Perovskite Structure for Use as a Magnetic Regenerator

    DEFF Research Database (Denmark)

    Pryds, Nini; Clemens, Frank; Menon, Mohan

    2011-01-01

    A La0.67Ca0.26Sr0.07Mn1.05O3 (LCSM) perovskite was prepared for the first time as a ceramic monolithic regenerator used in a regenerative magnetic refrigeration device. The parameters influencing the extrusion process and the performance of the regenerator, such as the nature of the monolith paste...

  19. Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

    NARCIS (Netherlands)

    Pedesseau, Laurent; Sapori, Daniel; Traore, Boubacar; Robles, Roberto; Fang, Hong-Hua; Loi, Maria Antonietta; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Neukirch, Amanda; Tretiak, Sergei; Mohite, Aditya D.; Katan, Claudine; Even, Jacky; Kepenekian, Mikael

    2016-01-01

    Layered halide hybrid organic inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells

  20. Perovskite solid electrolytes: Structure, transport properties and fuel cell applications

    DEFF Research Database (Denmark)

    Bonanos, N.; Knight, K.S.; Ellis, B.

    1995-01-01

    Doped barium cerate perovskites, first investigated by Iwahara and co-workers, have ionic conductivities of the order of 20 mS/cm at 800 degrees C making them attractive as fuel cell electrolytes for this temperature region. They have been used to construct laboratory scale fuel cells, which...

  1. Improving Perovskite Solar Cells: Insights From a Validated Device Model

    NARCIS (Netherlands)

    Sherkar, Tejas S.; Momblona, Cristina; Gil-Escrig, Lidon; Bolink, Henk J.; Koster, L. Jan Anton

    2017-01-01

    To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of conta

  2. Comprehensive design of omnidirectional high-performance perovskite solar cells

    Science.gov (United States)

    Zhang, Yutao; Xuan, Yimin

    2016-07-01

    The comprehensive design approach is established with coupled optical-electrical simulation for perovskite-based solar cell, which emerged as one of the most promising competitors to silicon solar cell for its low-cost fabrication and high PCE. The selection of structured surface, effect of geometry parameters, incident angle-dependence and polarization-sensitivity are considered in the simulation. The optical modeling is performed via the finite-difference time-domain method whilst the electrical properties are obtained by solving the coupled nonlinear equations of Poisson, continuity, and drift-diffusion equations. The optical and electrical performances of five different structured surfaces are compared to select a best structured surface for perovskite solar cell. The effects of the geometry parameters on the optical and electrical properties of the perovskite cell are analyzed. The results indicate that the light harvesting is obviously enhanced by the structured surface. The electrical performance can be remarkably improved due to the enhanced light harvesting of the designed best structured surface. The angle-dependence for s- and p-polarizations is investigated. The structured surface exhibits omnidirectional behavior and favorable polarization-insensitive feature within a wide incident angle range. Such a comprehensive design approach can highlight the potential of perovskite cell for power conversion in the full daylight.

  3. Improvements on Synthesis of Potassium Tris(oxalato) Ferrate(III) Trihydrate%三草酸合铁(III)酸钾合成方法的改进

    Institute of Scientific and Technical Information of China (English)

    肖圣雄; 王晓伦; 柏爱玲; 杨斌姣; 郭贤丽; 张禹; 蒋建宏; 刘文奇

    2016-01-01

    三草酸合铁(III)酸钾具有工业生产价值,其合成作为化学专业本科生的经典实验项目,按教材实验的效果却不尽人意。本文在严谨的化学平衡理论分析基础上,首次提出提高合成产率的关键是严格控制草酸和草酸钾的用量,改进后的合成条件为:氧化步骤H2O2的浓度为6%,水浴温度为40°C;充分氧化后,微沸2分钟;酸溶步骤中草酸稍微过量,草酸钾过量10%;结晶时做到充分冷却。经此改进,可简化操作,节约原料,实验室平均产率达87%,教学中学生实验平均产率超过70%。%Potassium tris(oxalato) ferrate(III) trihydrate has the industrial production value, and its synthesis is a classic experiment in the laboratory course for chemistry majors. However, results from the experimental procedure in the textbook are unsatisfactory. Based on the rigorous analysis of chemical equilibrium theory, we first proposed that the key factor for improving the yield is to strictly control the amount of oxalic acid and potassium oxalate. The improved synthesis conditions are as fol ows:in the oxidation step, the reaction is carried out at 40 oC, and the concentration of H2O2 is 6%;after ful oxidation, the solution is kept boiling for two minutes;a slight excess of oxalic acid and 10%excess of potassium oxalate are used in the acid dissolution step;sufficiently cooling is fol owed in crystal ization. With the improved procedure, operations are simplified and raw materials are saved. The yield is 87%for laboratory average and greater than 70%for students in the laboratory class.

  4. Architecture of the Interface between the Perovskite and Hole-Transport Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Moriya, Masahiro; Hirotani, Daisuke; Ohta, Tsuyoshi; Ogomi, Yuhei; Shen, Qing; Ripolles, Teresa S; Yoshino, Kenji; Toyoda, Taro; Minemoto, Takashi; Hayase, Shuzi

    2016-09-22

    The interface between the perovskite (PVK, CH3 NH3 PbI3 ) and hole-transport layers in perovskite solar cells is discussed. The device architecture studied is as follows: F-doped tin oxide (FTO)-coated glass/compact TiO2 /mesoporous TiO2 /PVK/2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-MeOTAD)/Au. After a thin layer of 4,4,4-trifluorobutylammonium iodide (TFBA) was inserted at the interface between PVK and Spiro-MeOTAD, the photovoltaic efficiency increased from 11.6-14.5 % to 15.1-17.6 %. TFBA (10 ppm) was added in the PVK solution before coating. Owing to the low surface tension of TFBA, TFBA rose to the surface of the PVK layer spontaneously during spin-coating to make a thin organic layer. The PVK grain boundaries also seemed to be passivated with the addition of TFBA. However, large differences in Urbach energies and valence band energy level were not observed for the PVK layer with and without the addition of TFBA. The charge recombination time constant between the PVK and the Spiro-MeOTAD became slower (from 8.4 to 280 μsec) after 10 ppm of TFBA was added in the PVK. The experimental results using TFBA conclude that insertion of a very thin layer at the interface between PVK and Spiro-MeOTAD is effective for suppressing charge recombination and increasing photovoltaic performances.

  5. Characterization of perovskite layer on various nanostructured silicon wafer

    Science.gov (United States)

    Rostan, Nur Fairuz Mohd; Sepeai, Suhaila; Ramli, Noor Fadhilah; Azhari, Ayu Wazira; Ludin, Norasikin Ahmad; Teridi, Mohd Asri Mat; Ibrahim, Mohd Adib; Zaidi, Saleem H.

    2017-05-01

    Crystalline silicon (c-Si) solar cell dominates 90% of photovoltaic (PV) market. The c-Si is the most mature of all PV technologies and expected to remain leading the PV technology by 2050. The attractive characters of Si solar cell are stability, long lasting and higher lifetime. Presently, the efficiency of c-Si solar cell is still stuck at 25% for one and half decades. Tandem approach is one of the attempts to improve the Si solar cell efficiency with higher bandgap layer is stacked on top of Si bottom cell. Perovskite offers a big potential to be inserted into a tandem solar cell. Perovskite with bandgap of 1.6 to 1.9 eV will be able to absorb high energy photons, meanwhile c-Si with bandgap of 1.124 eV will absorb low energy photons. The high carrier mobility, high carrier lifetime, highly compatible with both solution and evaporation techniques makes perovskite an eligible candidate for perovskite-Si tandem configuration. The solution of methyl ammonium lead iodide (MAPbI3) was prepared by single step precursor process. The perovskite layer was deposited on different c-Si surface structure, namely planar, textured and Si nanowires (SiNWs) by using spin-coating technique at different rotation speeds. The nanostructure of Si surface was textured using alkaline based wet chemical etching process and SiNW was grown using metal assisted etching technique. The detailed surface morphology and absorbance of perovskite were studied in this paper. The results show that the thicknesses of MAPbI3 were reduced with the increasing of rotation speed. In addition, the perovskite layer deposited on the nanostructured Si wafer became rougher as the etching time and rotation speed increased. The average surface roughness increased from ˜24 nm to ˜38 nm for etching time range between 5-60 min at constant low rotation speed (2000 rpm) for SiNWs Si wafer.

  6. Influence of void-free perovskite capping layer on the charge recombination process in high performance CH3NH3PbI3 perovskite solar cells.

    Science.gov (United States)

    Fu, Kunwu; Nelson, Christopher T; Scott, Mary Cooper; Minor, Andrew; Mathews, Nripan; Wong, Lydia Helena

    2016-02-21

    The stunning rise of methylammonium lead iodide perovskite material as a light harvesting material in recent years has drawn much attention in the photovoltaic community. Here, we investigated in detail the uniform and void-free perovskite capping layer in the mesoscopic perovskite devices and found it to play a critical role in determining device performance and charge recombination process. Compared to the rough surface with voids of the perovskite layer, surface of the perovskite capping layer obtained from sequential deposition process is much more uniform with less void formation and distribution within the TiO2 mesoscopic scaffold is more homogeneous, leading to much improved photovoltaic parameters of the devices. The impact of void free perovskite capping layer surface on the charge recombination processes within the mesoscopic perovskite solar cells is further scrutinized via charge extraction measurement. Modulation of precursor solution concentrations in order to further improve the perovskite layer surface morphology leads to higher efficiency and lower charge recombination rates. Inhibited charge recombination in these solar cells also matches with the higher charge density and slower photovoltage decay profiles measured.

  7. Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dewei; Yu, Yue; Wang, Changlei; Liao, Weiqiang; Shrestha, Niraj; Grice, Corey R.; Cimaroli, Alexander J.; Guan, Lei; Ellingson, Randy J.; Zhu, Kai; Zhao, Xingzhong; Xiong, Ren-Gen; Yan, Yanfa

    2017-03-01

    Tandem solar cells using only metal-halide perovskite sub-cells are an attractive choice for next-generation solar cells. However, the progress in developing efficient all-perovskite tandem solar cells has been hindered by the lack of high-performance low-bandgap perovskite solar cells. Here, we report efficient mixed tin-lead iodide low-bandgap (~1.25 eV) perovskite solar cells with open-circuit voltages up to 0.85 V and over 70% external quantum efficiencies in the infrared wavelength range of 700-900 nm, delivering a short-circuit current density of over 29 mA cm-2 and demonstrating suitability for bottom-cell applications in all-perovskite tandem solar cells. Our low-bandgap perovskite solar cells achieve a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01% with a negligible current-voltage hysteresis. When mechanically stacked with a ~1.58 eV bandgap perovskite top cell, our best all-perovskite 4-terminal tandem solar cell shows a steady-state efficiency of 21.0%.

  8. Research Update: Challenges for high-efficiency hybrid lead-halide perovskite LEDs and the path towards electrically pumped lasing

    Science.gov (United States)

    Li, Guangru; Price, Michael; Deschler, Felix

    2016-09-01

    Hybrid lead-halide perovskites have emerged as promising solution-processed semiconductor materials for thin-film optoelectronics. In this review, we discuss current challenges in perovskite LED performance, using thin-film and nano-crystalline perovskite as emitter layers, and look at device performance and stability. Fabrication of electrically pumped, optical-feedback devices with hybrid lead halide perovskites as gain medium is a future challenge, initiated by the demonstration of optically pumped lasing structures with low gain thresholds. We explain the material parameters affecting optical gain in perovskites and discuss the challenges towards electrically pumped perovskite lasers.

  9. Research Update: Challenges for high-efficiency hybrid lead-halide perovskite LEDs and the path towards electrically pumped lasing

    Directory of Open Access Journals (Sweden)

    Guangru Li

    2016-09-01

    Full Text Available Hybrid lead-halide perovskites have emerged as promising solution-processed semiconductor materials for thin-film optoelectronics. In this review, we discuss current challenges in perovskite LED performance, using thin-film and nano-crystalline perovskite as emitter layers, and look at device performance and stability. Fabrication of electrically pumped, optical-feedback devices with hybrid lead halide perovskites as gain medium is a future challenge, initiated by the demonstration of optically pumped lasing structures with low gain thresholds. We explain the material parameters affecting optical gain in perovskites and discuss the challenges towards electrically pumped perovskite lasers.

  10. 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.

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

    Science.gov (United States)

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

    2014-06-01

    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 La0.7Sr0.3FeO3, 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 (La0.7Sr0.3)(AlxFe1-x)O3 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 Fe4+ and Fe3+, 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 (La0.7Sr0.3)(AlxFe1-x)O3 perovskites have temperature-independence conductivity from 900 K.

  12. Interfacial Degradation of Planar Lead Halide Perovskite Solar Cells.

    Science.gov (United States)

    Guerrero, Antonio; You, Jingbi; Aranda, Clara; Kang, Yong Soo; Garcia-Belmonte, Germà; Zhou, Huanping; Bisquert, Juan; Yang, Yang

    2016-01-26

    The stability of perovskite solar cells is one of the major challenges for this technology to reach commercialization, with water believed to be the major degradation source. In this work, a range of devices containing different cathode metal contacts in the configuration ITO/PEDOT:PSS/MAPbI3/PCBM/Metal are fully electrically characterized before and after degradation caused by steady illumination during 4 h that induces a dramatic reduction in power conversion efficiency from values of 12 to 1.8%. We show that a decrease in performance and generation of the S-shape is associated with chemical degradation of the metal contact. Alternatively, use of Cr2O3/Cr as the contact enhances the stability, but modification of the energetic profile during steady illumination takes place, significantly reducing the performance. Several techniques including capacitance-voltage, X-ray diffraction, and optical absorption results suggest that the properties of the bulk perovskite layer are little affected in the device degradation process. Capacitance-voltage and impedance spectroscopy results show that the electrical properties of the cathode contact are being modified by generation of a dipole at the cathode that causes a large shift of the flat-band potential that modifies the interfacial energy barrier and impedes efficient extraction of electrons. Ionic movement in the perovskite layer changes the energy profile close to the contacts, modifying the energy level stabilization at the cathode. These results provide insights into the degradation mechanisms of perovskite solar cells and highlight the importance to further study the use of protecting layers to avoid the chemical reactivity of the perovskite with the external contacts.

  13. Modeling organohalide perovskites for photovoltaic applications: From materials to interfaces

    Science.gov (United States)

    de Angelis, Filippo

    2015-03-01

    The field of hybrid/organic photovoltaics has been revolutionized in 2012 by the first reports of solid-state solar cells based on organohalide perovskites, now topping at 20% efficiency. First-principles modeling has been widely applied to the dye-sensitized solar cells field, and more recently to perovskite-based solar cells. The computational design and screening of new materials has played a major role in advancing the DSCs field. Suitable modeling strategies may also offer a view of the crucial heterointerfaces ruling the device operational mechanism. I will illustrate how simulation tools can be employed in the emerging field of perovskite solar cells. The performance of the proposed simulation toolbox along with the fundamental modeling strategies are presented using selected examples of relevant materials and interfaces. The main issue with hybrid perovskite modeling is to be able to accurately describe their structural, electronic and optical features. These materials show a degree of short range disorder, due to the presence of mobile organic cations embedded within the inorganic matrix, requiring to average their properties over a molecular dynamics trajectory. Due to the presence of heavy atoms (e.g. Sn and Pb) their electronic structure must take into account spin-orbit coupling (SOC) in an effective way, possibly including GW corrections. The proposed SOC-GW method constitutes the basis for tuning the materials electronic and optical properties, rationalizing experimental trends. Modeling charge generation in perovskite-sensitized TiO2 interfaces is then approached based on a SOC-DFT scheme, describing alignment of energy levels in a qualitatively correct fashion. The role of interfacial chemistry on the device performance is finally discussed. The research leading to these results has received funding from the European Union Seventh Framework Programme [FP7/2007 2013] under Grant Agreement No. 604032 of the MESO project.

  14. 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.

  15. High-performance cadmium sulphide-based planar perovskite solar cell and the cadmium sulphide/perovskite interfaces

    Science.gov (United States)

    Peng, Haitao; Sun, Weihai; Li, Yunlong; Yan, Weibo; Yu, Pingrong; Zhou, Huanping; Bian, Zuqiang; Huang, Chunhui

    2016-04-01

    Planar heterojunction perovskite solar cell is one of the most competitive photovoltaic technologies, while charge transport materials play a crucial role. We successfully demonstrated an effective electron transport material, namely chemical bath deposited cadmium sulphide (CdS) film under low temperature, in perovskite-based solar cells. Power conversion efficiency of 16.1% has been achieved, which is comparable to that of devices based on TiO2 film prepared via low-temperature processes. Electronic impedance spectra reveal that the CdS-based device presents a higher recombination resistance than TiO2-based devices, which reduces carrier recombination and increases the open circuit voltage. The interface between CdS and perovskite was characterized with improved characteristics when compared to TiO2, e.g., efficient carrier extraction and reduced surface defect-associated degradation in the devices, which help to alleviate anomalous hysteresis and long-term instability. Furthermore, the entire device was fabricated via solution process with a processing temperature below 100°C, suggesting a promising method of further development of perovskite solar cells and commercial manufacturing.

  16. Solvent engineering for high-quality perovskite solar cell with an efficiency approaching 20%

    Science.gov (United States)

    Wu, Tongyue; Wu, Jihuai; Tu, Yongguang; He, Xin; Lan, Zhang; Huang, Miaoliang; Lin, Jianming

    2017-10-01

    The perovskite layer is the most crucial factor for the high performance perovskite solar cells. Based on solvent engineering, we develop a ternary-mixed-solvent method for the growth of high-quality [Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3] cation-anion-mixed perovskite films by introducing N-methyl-2-pyrrolidone (NMP) into the precursor mixed solution. By controlling rapid nucleation and retarding crystal growth via intermediate phase PbI2-NMP (Lewis acid-base adduct), a dense, large grain, pinhole-free and long charge carrier lifetime perovskite film is obtained. By optimizing the precursor solvent composition, the perovskite solar cell achieves an impressive power conversion efficiency of 19.61% under one-sun illumination. The research presented here provides a facile, low-cost and highly efficient way for the preparation of perovskite solar cells.

  17. 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.

  18. Observation and Mediation of the Presence of Metallic Lead in Organic-Inorganic Perovskite Films.

    Science.gov (United States)

    Sadoughi, Golnaz; Starr, David E; Handick, Evelyn; Stranks, Samuel D; Gorgoi, Mihaela; Wilks, Regan G; Bär, Marcus; Snaith, Henry J

    2015-06-24

    We have employed soft and hard X-ray photoelectron spectroscopies to study the depth-dependent chemical composition of mixed-halide perovskite thin films used in high-performance solar cells. We detect substantial amounts of metallic lead in the perovskite films, which correlate with significant density of states above the valence band maximum. The metallic lead content is higher in the bulk of the perovskite films than at the surface. Using an optimized postanneal process in air, we can reduce the metallic lead content in the perovskite film. This process reduces the amount of metallic lead and a corresponding increase in the photoluminescence quantum efficiency of the perovskite films can be observed. This correlation indicates that metallic lead impurities are likely a key defect whose concentration can be controlled by simple annealing procedures in order to increase the performance for perovskite solar cells.

  19. Enhancing Stability of Perovskite Solar Cells to Moisture by the Facile Hydrophobic Passivation.

    Science.gov (United States)

    Hwang, Insung; Jeong, Inyoung; Lee, Jinwoo; Ko, Min Jae; Yong, Kijung

    2015-08-12

    In this study, a novel and facile passivation process for a perovskite solar cell is reported. Poor stability in ambient atmosphere, which is the most critical demerit of a perovskite solar cell, is overcome by a simple passivation process using a hydrophobic polymer layer. Teflon, the hydrophobic polymer, is deposited on the top of a perovskite solar cell by a spin-coating method. With the hydrophobic passivation, the perovskite solar cell shows negligible degradation after a 30 day storage in ambient atmosphere. Suppressed degradation of the perovskite film is proved in various ways: X-ray diffraction, light absorption spectrum, and quartz crystal microbalance. This simple but effective passivation process suggests new kind of approach to enhance stability of perovskite solar cells to moisture.

  20. Benign-by-Design Solventless Mechanochemical Synthesis of Three-, Two-, and One-Dimensional Hybrid Perovskites.

    Science.gov (United States)

    Jodlowski, Alexander D; Yépez, Alfonso; Luque, Rafael; Camacho, Luis; de Miguel, Gustavo

    2016-11-21

    Organic-inorganic hybrid perovskites have attracted significant attention owing to their extraordinary optoelectronic properties with applications in the fields of solar energy, lighting, photodetectors, and lasers. The rational design of these hybrid materials is a key factor in the optimization of their performance in perovskite-based devices. Herein, a mechanochemical approach is proposed as a highly efficient, simple, and reproducible method for the preparation of four types of hybrid perovskites, which were obtained in large amounts as polycrystalline powders with high purity and excellent optoelectronics properties. Two archetypal three-dimensional (3D) perovskites (MAPbI3 and FAPbI3 ) were synthesized, together with a bidimensional (2D) perovskite (Gua2 PbI4 ) and a "double-chain" one-dimensional (1D) perovskite (GuaPbI3 ), whose structure was elucidated by X-ray diffraction.

  1. Formation of Single-mode Laser in Perovskite Nanowire via Nano-manipulation

    CERN Document Server

    Wang, Kaiyang; Liu, Shuai; Li, Jiankai; Xiao, Shumin; Song, Qinghai

    2015-01-01

    Perovskite based micro- and nano- lasers have attracted considerable research attention in past two years. However, the properties of perovskite devices are mostly fixed once they are synthesized. Here we demonstrate the tailoring of lasing properties of perovskite nanowire lasers via nano-manipulation. By utilizing a tungsten probe, one nanowire has been lifted from the wafer and re-positioned its two ends on two nearby perovskite blocks. Consequently, the conventional Fabry-Perot lasers are completely suppressed and a single laser peak has been observed. The corresponding numerical model reveals that the single-mode lasing operation is formed by the whispering gallery mode in the transverse plane of perovskite nanowire. Our research provides a simple way to tailor the properties of nanowire and it will be essential for the applications of perovskite optoelectronics.

  2. A discussion on the origin and solutions of hysteresis in perovskite hybrid solar cells

    Science.gov (United States)

    Song, Dae Ho; Hyeok Jang, Min; Lee, Min Ho; Hyuck Heo, Jin; Park, Jin Kyoung; Sung, Shi-Joon; Kim, Dae-Hwan; Hong, Ki-Ha; Im, Sang Hyuk

    2016-11-01

    Although the record efficiencies of perovskite hybrid solar cells are gradually reaching the efficiency of crystalline Si solar cells, perovskite hybrid solar cells often exhibit significant current density-voltage (J-V) hysteresis with respect to the forward and reverse scan direction and scan rate. The origin of the J-V hysteresis of perovskite hybrid solar cells has not, to date, been clearly elucidated. Dielectric polarization by the ferroelectric properties of perovskite (i), the ionic motion/migration of perovskite materials (ii), and charge trapping and detrapping at trap sites by the unbalanced electron and hole flux (iii) are considered the possible origins of J-V hysteresis. Here, we reviewed the origin of the J-V hysteresis of perovskite solar cells from the above three points of view and we then suggest how one may reduce the J-V hysteresis with respect to the scan direction and scan rate.

  3. Thermal expansion and structural distortion of perovskite — data for NaMgF 3 perovskite. Part I

    Science.gov (United States)

    Zhao, Yusheng; Weidner, Donald J.; Parise, John B.; Cox, David E.

    1993-02-01

    The crystal structure of NaMgF 3 perovskite (Neighborite) has been studied at high temperature by X-ray powder diffraction. Data were collected using a position sensitive detector with a monochromatic synchroton radiation source. Changes in unit cell and atomic positions of the perovskite structure were defined using the Rietveld refinement technique. The linear and volumetric thermal expansion coefficients are observed to be αa = 4.04 × 10 -5 K -1, αb = 1.53 × 10 -5 K -1, αc = 3.06 × 10 -5 K -1, αv = 8.80 × 10 -5 K -1 for the orthorhombic Pbnm phase, and αa0 = 3.16 × 10 -5 K -1, αv0 = 9.49 × 10 -5 K -1 for the cubic Pm3m phase of NaMgF 3 perovskite, respectively. The temperature-induced linear and volumetric changes of the centrosymmetrically distorted ABX 3 perovskite structure can be empirically expressed as a combination of the change of the (BX) bond length and the change of tilting of the BX 6 octahedral framework. The considerable anisotropy of linear thermal expansion, αa > αc > αb, for the orthorhombic Pbnm phase reflects the progressive decrease of structural distortion and the development of the phase transition of the NaMgF 3 perovskite. The tilting angle of the MgF 6 octahedral framework is observed to decrease rapidly toward zero as the temperature approaches Tc = 765°C in the manner expected for a ferroelastic phase transition. More interestingly, the apparent (MgF) bond lengths of the MgF 6 octahedra shrink dramatically throughout a temperature interval of about 100°C before the phase transition. The volumetric thermal expansion increases drastically in a critical manner as the temperature approaches Tc.

  4. Hybrid Perovskite Thin-Film Photovoltaics: In Situ Diagnostics and Importance of the Precursor Solvate Phases.

    Science.gov (United States)

    Munir, Rahim; Sheikh, Arif D; Abdelsamie, Maged; Hu, Hanlin; Yu, Liyang; Zhao, Kui; Kim, Taesoo; Tall, Omar El; Li, Ruipeng; Smilgies, Detlef-M; Amassian, Aram

    2017-01-01

    Solution-processed hybrid perovskite semiconductors attract a great deal of attention, but little is known about their formation process. The one-step spin-coating process of perovskites is investigated in situ, revealing that thin-film formation is mediated by solid-state precursor solvates and their nature. The stability of these intermediate phases directly impacts the quality and reproducibility of thermally converted perovskite films and their photovoltaic performance.

  5. Solution-Processed Organic-Inorganic Perovskite Field-Effect Transistors with High Hole Mobilities.

    Science.gov (United States)

    Matsushima, Toshinori; Hwang, Sunbin; Sandanayaka, Atula S D; Qin, Chuanjiang; Terakawa, Shinobu; Fujihara, Takashi; Yahiro, Masayuki; Adachi, Chihaya

    2016-12-01

    A very high hole mobility of 15 cm(2) V(-1) s(-1) along with negligible hysteresis are demonstrated in transistors with an organic-inorganic perovskite semiconductor. This high mobility results from the well-developed perovskite crystallites, improved conversion to perovskite, reduced hole trap density, and improved hole injection by employing a top-contact/top-gate structure with surface treatment and MoOx hole-injection layers.

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

    OpenAIRE

    Shany Gamliel; Inna Popov; Bat-El Cohen; Vladimir Uvarov; Lioz Etgar

    2016-01-01

    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 af...

  7. Hybrid Perovskite Thin-Film Photovoltaics: In Situ Diagnostics and Importance of the Precursor Solvate Phases

    KAUST Repository

    Munir, Rahim

    2016-11-07

    Solution-processed hybrid perovskite semiconductors attract a great deal of attention, but little is known about their formation process. The one-step spin-coating process of perovskites is investigated in situ, revealing that thin-film formation is mediated by solid-state precursor solvates and their nature. The stability of these intermediate phases directly impacts the quality and reproducibility of thermally converted perovskite films and their photovoltaic performance.

  8. Humidity versus photo-stability of metal halide perovskite films in a polymer matrix.

    Science.gov (United States)

    Manshor, Nurul Ain; Wali, Qamar; Wong, Ka Kan; Muzakir, Saifful Kamaluddin; Fakharuddin, Azhar; Schmidt-Mende, Lukas; Jose, Rajan

    2016-08-21

    Despite the high efficiency of over 21% reported for emerging thin film perovskite solar cells, one of the key issues prior to their commercial deployment is to attain their long term stability under ambient and outdoor conditions. The instability in perovskite is widely conceived to be humidity induced due to the water solubility of its initial precursors, which leads to decomposition of the perovskite crystal structure; however, we note that humidity alone is not the major degradation factor and it is rather the photon dose in combination with humidity exposure that triggers the instability. In our experiment, which is designed to decouple the effect of humidity and light on perovskite degradation, we investigate the shelf-lifetime of CH3NH3PbI3 films in the dark and under illumination under high humidity conditions (Rel. H. > 70%). We note minor degradation in perovskite films stored in a humid dark environment whereas upon exposure to light, the films undergo drastic degradation, primarily owing to the reactive TiO2/perovskite interface and also the surface defects of TiO2. To enhance its air-stability, we incorporate CH3NH3PbI3 perovskite in a polymer (poly-vinylpyrrolidone, PVP) matrix which retained its optical and structural characteristics in the dark for ∼2000 h and ∼800 h in room light soaking, significantly higher than a pristine perovskite film, which degraded completely in 600 h in the dark and in less than 100 h when exposed to light. We attribute the superior stability of PVP incorporated perovskite films to the improved structural stability of CH3NH3PbI3 and also to the improved TiO2/perovskite interface upon incorporating a polymer matrix. Charge injection from the polymer embedded perovskite films has also been confirmed by fabricating solar cells using them, thereby providing a promising future research pathway for stable and efficient perovskite solar cells.

  9. Preface for Special Topic: Perovskite solar cells—A research update

    Science.gov (United States)

    Schmidt-Mende, Lukas; Herz, Laura M.

    2016-09-01

    Over the last few years, tremendous progress has been made in the research field of perovskite solar cells. Not only are record power conversion efficiencies now exceeding 20%, but our understanding about the different mechanisms leading to this extraordinary performance has improved phenomenally. The aim of this special issue is to review the current state-of-the-art understanding of perovskite solar cells. Most of the presented articles are research updates giving a succinct overview over different aspects concerning perovskite solar cells.

  10. Polar Behavior in a Magnetic Perovskite Via A-Site Size Disorder

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chul-Hong [ORNL; Singh, David J [ORNL

    2008-01-01

    We elucidate a mechanism for obtaining polar behavior in magnetic perovskites based on A-site disorder and demonstrate this mechanism by density functional calculations for the double perovskite (La,Lu)MnNiO{sub 6} with Lu concentrations at and below 50%. We show that this material combines polar behavior and ferromagnetism. The mechanism is quite general and may be applicable to a wide range of magnetic perovskites.

  11. Polar Behavior in a Magnetic Perovskite from A-Site Size Disorder: A Density Functional Study

    Science.gov (United States)

    Singh, D. J.; Park, Chul Hong

    2008-02-01

    We elucidate a mechanism for obtaining polar behavior in magnetic perovskites based on A-site disorder and demonstrate this mechanism by density functional calculations for the double perovskite (La,Lu)MnNiO6 with Lu concentrations at and below 50%. We show that this material combines polar behavior and ferromagnetism. The mechanism is quite general and may be applicable to a wide range of magnetic perovskites.

  12. High-Efficiency Flexible Solar Cells Based on Organometal Halide Perovskites.

    Science.gov (United States)

    Wang, Yuming; Bai, Sai; Cheng, Lu; Wang, Nana; Wang, Jianpu; Gao, Feng; Huang, Wei

    2016-06-01

    Flexible and light-weight solar cells are important because they not only supply power to wearable and portable devices, but also reduce the transportation and installation cost of solar panels. High-efficiency organometal halide perovskite solar cells can be fabricated by a low-temperature solution process, and hence are promising for flexible-solar-cell applications. Here, the development of perovskite solar cells is briefly discussed, followed by the merits of organometal halide perovskites as promising candidates as high-efficiency, flexible, and light-weight photovoltaic materials. Afterward, recent developments of flexible solar cells based on perovskites are reviewed.

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

    OpenAIRE

    Seigo Ito; Shusaku Kanaya; Hitoshi Nishino; Tomokazu Umeyama; Hiroshi Imahori

    2015-01-01

    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 stabili...

  14. 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.

  15. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Alison [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100°C for 90 minutes followed by 120°C for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulk photoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.

  16. Research Update: Physical and electrical characteristics of lead halide perovskites for solar cell applications

    Directory of Open Access Journals (Sweden)

    Simon A. Bretschneider

    2014-04-01

    Full Text Available The field of thin-film photovoltaics has been recently enriched by the introduction of lead halide perovskites as absorber materials, which allow low-cost synthesis of solar cells with efficiencies exceeding 16%. The exact impact of the perovskite crystal structure and composition on the optoelectronic properties of the material are not fully understood. Our progress report highlights the knowledge gained about lead halide perovskites with a focus on physical and optoelectronic properties. We discuss the crystal and band structure of perovskite materials currently implemented in solar cells and the impact of the crystal properties on ferroelectricity, ambipolarity, and the properties of excitons.

  17. Life Cycle Assessment of Titania Perovskite Solar Cell Technology for Sustainable Design and Manufacturing.

    Science.gov (United States)

    Zhang, Jingyi; Gao, Xianfeng; Deng, Yelin; Li, Bingbing; Yuan, Chris

    2015-11-01

    Perovskite solar cells have attracted enormous attention in recent years due to their low cost and superior technical performance. However, the use of toxic metals, such as lead, in the perovskite dye and toxic chemicals in perovskite solar cell manufacturing causes grave concerns for its environmental performance. To understand and facilitate the sustainable development of perovskite solar cell technology from its design to manufacturing, a comprehensive environmental impact assessment has been conducted on titanium dioxide nanotube based perovskite solar cells by using an attributional life cycle assessment approach, from cradle to gate, with manufacturing data from our laboratory-scale experiments and upstream data collected from professional databases and the literature. The results indicate that the perovskite dye is the primary source of environmental impact, associated with 64.77% total embodied energy and 31.38% embodied materials consumption, contributing to more than 50% of the life cycle impact in almost all impact categories, although lead used in the perovskite dye only contributes to about 1.14% of the human toxicity potential. A comparison of perovskite solar cells with commercial silicon and cadmium-tellurium solar cells reveals that perovskite solar cells could be a promising alternative technology for future large-scale industrial applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Superior stability for perovskite solar cells with 20% efficiency using vacuum co-evaporation.

    Science.gov (United States)

    Zhu, Xuejie; Yang, Dong; Yang, Ruixia; Yang, Bin; Yang, Zhou; Ren, Xiaodong; Zhang, Jian; Niu, Jinzhi; Feng, Jiangshan; Liu, Shengzhong Frank

    2017-08-31

    Chemical composition and film quality are two key figures of merit for large-area high-efficiency perovskite solar cells. To date, all studies on mixed perovskites have used solution-processing, which results in imperfect surface coverage and pin-holes generated during solvent evaporation, execrably influencing the stability and efficiency of perovskite solar cells. Herein, we report our development using a vacuum co-evaporation deposition method to fabricate pin-hole-free cesium (Cs)-substituted perovskite films with complete surface coverage. Apart from the simplified procedure, the present method also promises tunable band gap, reduced trap-state density and longer carrier lifetime, leading to solar cell efficiency as high as 20.13%, which is among the highest reported for planar perovskite solar cells. The splendid performance is attributed to superior merits of the Cs-substituted perovskite film including tunable band gap, reduced trap-state density and longer carrier lifetime. Moreover, the Cs-substituted perovskite device without encapsulation exhibits significantly higher stability in ambient air compared with the single-component counterpart. When the Cs-substituted perovskite solar cells are stored in dark for one year, the PCE remains at 19.25%, degrading only 4.37% of the initial efficiency. The excellent stability originates from reduced lattice constant and relaxed strain in perovskite lattice by incorporating Cs cations into the crystal lattice, as demonstrated by the positive peak shifts and reduced peak width in X-ray diffraction analysis.

  19. Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

    Directory of Open Access Journals (Sweden)

    C. Momblona

    2014-08-01

    Full Text Available Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.

  20. 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.

  1. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Alison J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-25

    Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100 degree Celsius for 90 minutes followed by 120 degree Celsius for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulkphotoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.

  2. Recent progress of dopant-free organic hole-transporting materials in perovskite solar cells

    Science.gov (United States)

    Dongxue, Liu; Liu, Yongsheng

    2017-01-01

    Organic–inorganic hybrid perovskite solar cells have undergone especially intense research and transformation over the past seven years due to their enormous progress in conversion efficiencies. In this perspective, we review the latest developments of conventional perovskite solar cells with a main focus on dopant-free organic hole transporting materials (HTMs). Regarding the rapid progress of perovskite solar cells, stability of devices using dopant-free HTMs are also discussed to help readers understand the challenges and opportunities in high performance and stable perovskite solar cells. Project supported by the Scientific Research Starting Foundation for Overseas Introduced Talents of College of Chemistry, Nankai University.

  3. Reversible Structural Swell-Shrink and Recoverable Optical Properties in Hybrid Inorganic-Organic Perovskite.

    Science.gov (United States)

    Zhang, Yupeng; Wang, Yusheng; Xu, Zai-Quan; Liu, Jingying; Song, Jingchao; Xue, Yunzhou; Wang, Ziyu; Zheng, Jialu; Jiang, Liangcong; Zheng, Changxi; Huang, Fuzhi; Sun, Baoquan; Cheng, Yi-Bing; Bao, Qiaoliang

    2016-07-26

    Ion migration in hybrid organic-inorganic perovskites has been suggested to be an important factor for many unusual behaviors in perovskite-based optoelectronics, such as current-voltage hysteresis, low-frequency giant dielectric response, and the switchable photovoltaic effect. However, the role played by ion migration in the photoelectric conversion process of perovskites is still unclear. In this work, we provide microscale insights into the influence of ion migration on the microstructure, stability, and light-matter interaction in perovskite micro/nanowires by using spatially resolved optical characterization techniques. We observed that ion migration, especially the migration of MA(+) ions, will induce a reversible structural swell-shrink in perovskites and recoverably affect the reflective index, quantum efficiency, light-harvesting, and photoelectric properties. The maximum ion migration quantity in perovskites was as high as approximately 30%, resulting in lattice swell or shrink of approximately 4.4%. Meanwhile, the evidence shows that ion migration in perovskites could gradually accelerate the aging of perovskites because of lattice distortion in the reversible structural swell-shrink process. Knowledge regarding reversible structural swell-shrink and recoverable optical properties may shed light on the development of optoelectronic and converse piezoelectric devices based on perovskites.

  4. The influence of morphology on charge transport/recombination dynamics in planar perovskite solar cells

    Science.gov (United States)

    Yu, Man; Wang, Yi; Wang, Hao-Yi; Han, Jun; Qin, Yujun; Zhang, Jian-Ping; Ai, Xi-Cheng

    2016-10-01

    The photovoltaic performance of planar perovskite solar cell is significantly influenced by the morphology of perovskite film. In this work, five kinds of devices with different perovskite film morphologies were prepared by varying the concentration of CH3NH3Cl in precursor solutions. We found that best morphology of perovskite film results in the excellent photovoltaic performance with an average efficiency of 15.52% and a champion efficiency of 16.38%. Transient photovoltage and photocurrent measurements are performed to elucidate the mechanism of photoelectric conversion processes, which shows that the charge recombination is effectively suppressed and the charge transport is obviously promoted by optimized morphology.

  5. Cooperative Tin Oxide Fullerene Electron Selective Layers for High-Performance Planar Perovskite Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Weijun; Zhao, Dewei; Xiao, Chuanxiao; Wang, Changlei; Cimaroli, Alexander J.; Grice, Corey R.; Yang, Mengjin; Li, Zhen; Jiang, Chun-Sheng; Al-Jassim, Mowafak; Zhu, Kai; Kanatzidis, Mercouri G.; Fang, Guojia; Yan, Yanfa

    2016-10-07

    Both tin oxide (SnO2) and fullerenes have been reported as electron selective layers (ESLs) for producing efficient lead halide perovskite solar cells. Here, we report that SnO2 and fullerenes can work cooperatively to further boost the performance of perovskite solar cells. We find that fullerenes can be redissolved during perovskite deposition, allowing ultra-thin fullerenes to be retained at the interface and some dissolved fullerenes infiltrate into perovskite grain boundaries. The SnO2 layer blocks holes effectively; whereas, the fullerenes promote electron transfer and passivate both the SnO2/perovskite interface and perovskite grain boundaries. With careful device optimization, the best-performing planar perovskite solar cell using a fullerene passivated SnO2 ESL has achieved a steady-state efficiency of 17.75% and a power conversion efficiency of 19.12% with an open circuit voltage of 1.12 V, a short-circuit current density of 22.61 mA cm-2, and a fill factor of 75.8% when measured under reverse voltage scanning. We find that the partial dissolving of fullerenes during perovskite deposition is the key for fabricating high-performance perovskite solar cells based on metal oxide/fullerene ESLs.

  6. Superior solid solubility of MnSiO3 in CaSiO3 perovskite

    Science.gov (United States)

    Li, Lin; Nagai, Takaya; Seto, Yusuke; Fujino, Kiyoshi; Kawano, Jun; Itoh, Shoich

    2015-02-01

    The silicate perovskite phase relation between CaSiO3 and MnSiO3 was investigated at 35-52 GPa and at 1,800 K using laser-heated diamond anvil cells combined with angle-dispersive synchrotron X-ray diffraction and energy-dispersive X-ray spectroscopic chemical analyses with scanning or transmission electron microscopy. We found that MnSiO3 can be incorporated into CaSiO3 perovskite up to 55, and 20 mol % of CaSiO3 is soluble in MnSiO3 perovskite. The range of 55-80 mol % of MnSiO3 in the CaSiO3-MnSiO3 perovskite system could be immiscible. We also observed that the two perovskite structured phases of the Mn-bearing CaSiO3 and the Ca-bearing MnSiO3 coexisted at these conditions. The Mn-bearing CaSiO3 perovskite has non-cubic symmetry and the Ca-bearing MnSiO3 perovskite has an orthorhombic structure with space group Pbnm. All the perovskite structured phases in the CaSiO3-MnSiO3 system convert to the amorphous phase during pressure release. MnSiO3 is the first chemical component confirmed to show such a superior solid solubility in CaSiO3 perovskite.

  7. Film Grain-Size Related Long-Term Stability of Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Chiang, Chien-Hung; Wu, Chun-Guey

    2016-09-22

    The power conversion efficiency (PCE) of the perovskite solar cell is high enough to be commercially viable. The next important issue is the stability of the device. This article discusses the effect of the perovskite grain-size on the long-term stability of inverted perovskite solar cells. Perovskite films composed of various sizes of grains were prepared by controlling the solvent annealing time. The grain-size related stability of the inverted cells was investigated both in ambient atmosphere at relative humidity of approximately 30-40 % and in a nitrogen filled glove box (H2 Osolar cell based on a perovskite film having the grain size larger than 1 μm (D-10) decreases less than 10 % with storage in a glove box and less than 15 % when it was stored under an ambient atmosphere for 30 days. However, the cell using the perovskite film composed of small (∼100 nm) perovskite grains (D-0) exhibits complete loss of PCE after storage under the ambient atmosphere for only 15 days and a PCE loss of up to 70 % with storage in the glove box for 30 days. These results suggest that, even under H2 O-free conditions, the chemical- and thermal-induced production of pin holes at the grain boundaries of the perovskite film could be the reason for long-term instability of inverted perovskite solar cells.

  8. Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

    Energy Technology Data Exchange (ETDEWEB)

    Momblona, C.; Malinkiewicz, O.; Soriano, A.; Gil-Escrig, L.; Bandiello, E.; Scheepers, M.; Bolink, H. J., E-mail: henk.bolink@uv.es [Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna, Valencia (Spain); Roldán-Carmona, C. [Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna, Valencia (Spain); Department of Physical Chemistry and Applied Thermodynamics, University of Córdoba, Campus Rabanales, Ed. C3, 14014, Córdoba (Spain); Edri, E. [Department of Materials and Interfaces, Weizmann Institute of Science, Herzl St. 34, Rehovot 76100 (Israel)

    2014-08-01

    Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.

  9. Meniscus-assisted solution printing of large-grained perovskite films for high-efficiency solar cells

    Science.gov (United States)

    He, Ming; Li, Bo; Cui, Xun; Jiang, Beibei; He, Yanjie; Chen, Yihuang; O'Neil, Daniel; Szymanski, Paul; Ei-Sayed, Mostafa A.; Huang, Jinsong; Lin, Zhiqun

    2017-07-01

    Control over morphology and crystallinity of metal halide perovskite films is of key importance to enable high-performance optoelectronics. However, this remains particularly challenging for solution-printed devices due to the complex crystallization kinetics of semiconductor materials within dynamic flow of inks. Here we report a simple yet effective meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparts the transport of perovskite solutes, thus facilitating the growth of micrometre-scale perovskite grains. The growth kinetics of perovskite crystals is scrutinized by in situ optical microscopy tracking to understand the crystallization mechanism. The perovskite films produced by MASP exhibit excellent optoelectronic properties with efficiencies approaching 20% in planar perovskite solar cells. This robust MASP strategy may in principle be easily extended to craft other solution-printed perovskite-based optoelectronics.

  10. Ferroelectric and Piezoelectric properties of (111) oriented lanthanum modified lead zirconate titanate film

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Soma, E-mail: som@nal.res.in; Antony Jeyaseelan, A.; Sruthi, S.

    2014-07-01

    Lanthanum modified lead zirconate titanate (PLZT) thick film with molecular formula of Pb{sub 0.92}La{sub 0.08}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.98}O{sub 3} was grown preferentially along (111) direction on Pt/SiO{sub 2}/Si (platinum/silicon oxide/silicon) substrate by spin coating of chemical solution. The directional growth of the film was facilitated by platinum (Pt) (111) template and rapid thermal annealing. X-ray diffraction pattern and atomic force microscopy revealed the preferential growth of the PLZT film. The film was characterized for ferroelectric and detailed piezoelectric properties in a parallel plate capacitor (metal–PLZT–metal) configuration. Ferroelectric characterization of the film showed saturated hysteresis loop with remanent polarization and coercive electric field values of 10.14 μC/cm{sup 2} and 42 kV/cm, respectively, at an applied field of 300 kV/cm. Longitudinal piezoelectric coefficient (d{sub 33,f}) was measured by employing converse piezoelectric effect where electrical charge response and displacement were measured with electrical voltage excitation on the sample electrodes. The effective transverse piezoelectric coefficient (e{sub 31,f}) was derived from charge measurement with an applied mechanical excitation strain by using the four point bending method. d{sub 33,f} and e{sub 31,f} coefficients of PLZT films were found to be 380 pm/V and − 0.831 C/m{sup 2} respectively. - Highlights: • PLZT (111) film is prepared by spin coating of chemical sol on Pt (111) template. • Piezoelectric d{sub 33} value (380 pm/V) of PLZT film is found 20% higher than PZT. • Transverse piezocoefficient e{sub 31,f} of PLZT film is reported for the first time.

  11. Research Update: Challenges for high-efficiency hybrid lead-halide perovskite LEDs and the path towards electrically pumped lasing

    OpenAIRE

    Guangru Li; Michael Price; Felix Deschler

    2016-01-01

    Hybrid lead-halide perovskites have emerged as promising solution-processed semiconductor materials for thin-film optoelectronics. In this review, we discuss current challenges in perovskite LED performance, using thin-film and nano-crystalline perovskite as emitter layers, and look at device performance and stability. Fabrication of electrically pumped, optical-feedback devices with hybrid lead halide perovskites as gain medium is a future challenge, initiated by the demonstration of optical...

  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. Effect of the solvent used for fabrication of perovskite films by solvent dropping on performance of perovskite light-emitting diodes.

    Science.gov (United States)

    Yu, Jae Choul; Kim, Dae Woo; Kim, Da Bin; Jung, Eui Dae; Lee, Ki-Suk; Lee, Sukbin; Nuzzo, Daniele Di; Kim, Ji-Seon; Song, Myoung Hoon

    2017-02-02

    Organic-inorganic hybrid perovskites have emerged as a next-generation candidate for light-emitting device applications due to their excellent optical and electrical properties with narrow band emission compared to organic emitters. The morphological control of perovskite films with full surface coverage and few defect sites is essential for achieving highly efficient perovskite light-emitting diodes (PeLEDs). Here, we obtain a highly uniform perovskite film with a remarkably reduced number of defect sites in a perovskite crystal using chlorobenzene dropping. This effort leads to the enhanced performance of PeLEDs with a CH3NH3PbBr3 film using chlorobenzene dropping with a maximum luminance of 14 460 cd m(-2) (at 3.8 V) and a maximum external quantum efficiency (EQE) of 0.71% (at 2.8 V). This research confirms that the role of the solvent in the solvent dropping method is to fabricate a dense and uniform perovskite film and to passivate the defect sites of the perovskite crystal films.

  14. Optical analysis of CH3NH3Sn x Pb1-x I3 absorbers: a roadmap for perovskite-on-perovskite tandem solar cells.

    Science.gov (United States)

    Anaya, Miguel; Correa-Baena, Juan P; Lozano, Gabriel; Saliba, Michael; Anguita, Pablo; Roose, Bart; Abate, Antonio; Steiner, Ullrich; Grätzel, Michael; Calvo, Mauricio E; Hagfeldt, Anders; Míguez, Hernán

    2016-08-07

    Organic-inorganic perovskite structures in which lead is substituted by tin are exceptional candidates for broadband light absorption. Herein we present a thorough analysis of the optical properties of CH3NH3Sn x Pb1-x I3 films, providing the field with definitive insights about the possibilities of these materials for perovskite solar cells of superior efficiency. We report a user's guide based on the first set of optical constants obtained for a series of tin/lead perovskite films, which was only possible to measure due to the preparation of optical quality thin layers. According to the Shockley-Queisser theory, CH3NH3Sn x Pb1-x I3 compounds promise a substantial enhancement of both short circuit photocurrent and power conversion efficiency in single junction solar cells. Moreover, we propose a novel tandem architecture design in which both top and bottom cells are made of perovskite absorbers. Our calculations indicate that such perovskite-on-perovskite tandem devices could reach efficiencies over 35%. Our analysis serves to establish the first roadmap for this type of cells based on actual optical characterization data. We foresee that this study will encourage the research on novel near-infrared perovskite materials for photovoltaic applications, which may have implications in the rapidly emerging field of tandem devices.

  15. Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI2 Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy.

    Science.gov (United States)

    Shih, Min-Chuan; Li, Shao-Sian; Hsieh, Cheng-Hua; Wang, Ying-Chiao; Yang, Hung-Duen; Chiu, Ya-Ping; Chang, Chia-Seng; Chen, Chun-Wei

    2017-02-08

    The presence of the PbI2 passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CH3NH3PbI3 perovskite crystals and PbI2 passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains. By systematically exploring the interfacial electronic structures of individual perovskite grains, enhanced charge separation and reduced back recombination were observed when an optimal design of interfacial PbI2 passivation layers consisting of a thickness less than 20 nm at perovskite crystal grains was applied.

  16. Fast Photoconductive Responses in Organometal Halide Perovskite Photodetectors.

    Science.gov (United States)

    Wang, Fei; Mei, Jingjing; Wang, Yunpeng; Zhang, Ligong; Zhao, Haifeng; Zhao, Dongxu

    2016-02-03

    Inorganic semiconductor-based photodetectors have been suffering from slow response speeds, which are caused by the persistent photoconductivity of semiconductor materials. For realizing high speed optoelectronic devices, the organometal halide perovskite thin films were applied onto the interdigitated (IDT) patterned Au electrodes, and symmetrical structured photoconductive detectors were achieved. The detectors were sensitive to the incident light signals, and the photocurrents of the devices were 2-3 orders of magnitude higher than dark currents. The responsivities of the devices could reach up to 55 mA W(1-). Most importantly, the detectors have a fast response time of less than 20 μs. The light and bias induced dipole rearrangement in organometal perovskite thin films has resulted in the instability of photocurrents, and Ag nanowires could quicken the process of dipole alignment and stabilize the photocurrents of the devices.

  17. Photostability of 2D Organic-Inorganic Hybrid Perovskites

    Directory of Open Access Journals (Sweden)

    Yi Wei

    2014-06-01

    Full Text Available We analyze the behavior of a series of newly synthesized (R-NH32PbX4 perovskites and, in particular, discuss the possible reasons which cause their degradation under UV illumination. Experimental results show that the degradation process depends a lot on their molecular components: not only the inorganic part, but also the chemical structure of the organic moieties play an important role in bleaching and photo-chemical reaction processes which tend to destroy perovskites luminescent framework. In addition, we find the spatial arrangement in crystal also influences the photostability course. Following these trends, we propose a plausible mechanism for the photodegradation of the films, and also introduced options for optimized stability.

  18. Perovskite Oxide Thin Film Growth, Characterization, and Stability

    Science.gov (United States)

    Izumi, Andrew

    Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr 0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO 3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr 2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11¯0] surface axis. This allows the NSMO film enough

  19. A novel synthesis of perovskite bismuth ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Alexandre Z. Simões

    2011-09-01

    Full Text Available Microwave assisted hydrothermal (MAH method was used to synthesize crystalline bismuth ferrite (BiFeO3 nanoparticles (BFO at temperature of 180°C with times ranging from 5 min to 1 h. For comparison, BFO powders were also crystallized by the soft chemistry route in a conventional furnace at a temperature of 850°C for 4 h. X-ray diffraction (XRD results verified the formation of perovskite BFO crystallites while infrared data showed no traces of carbonate. Field emission scanning microcopy (FE/SEM revealed a homogeneous size distribution of nanometric BFO powders. MAH method produced nanoparticles of 96% pure perovskite, with a size of 130 nm. These results are in agreement with Raman scattering values which show that the MAH synthesis route is rapid and cost effective. This method could be used as an alternative to other chemical methods in order to obtain BFO nanoparticles.

  20. Photoinduced surface voltage mapping study for large perovskite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaojing; Liu, Yucheng; Gao, Fei; Yang, Zhou [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Liu, Shengzhong, E-mail: liusz@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Dalian Institute of Chemical Physics, iChEM, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian 116023 (China)

    2016-05-02

    Using a series of illumination sources, including white light (tungsten-halogen lamp), 445-nm, 532-nm, 635-nm, and 730-nm lasers, the surface photovoltage (SPV) images were mapped for centimeter-sized CH{sub 3}NH{sub 3}PbX{sub 3} (X = Cl, Br, I) perovskite single crystals using Kelvin probe force microscopy. The significant SPV signals were observed to be wavelength-dependent. We attribute the appreciable SPV to the built-in electric field in the space charge region. This study shines light into the understanding of photoinduced charge generation and separation processes at nanoscale to help advance the development of perovskite solar cells, optoelectronics, laser, photodetector, and light-emitting diode (LED).