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Sample records for bulk heterojunction solar

  1. Morphology Control in co-evaporated bulk heterojunction solar cells

    OpenAIRE

    Kovacik, P; Assender, HE; Watt, AAR

    2013-01-01

    Bulk heterojunction solar cells made by vacuum co-evaporation of polythiophene (PTh) and fullerene (C60) are reported and the blend morphology control through donor-acceptor composition and post-situ annealing demonstrated. Co-deposited heterojunctions are shown to generate about 60% higher photocurrents than their thickness-optimized PTh/C60 planar heterojunction counterparts. Furthermore, by annealing the devices post-situ the power conversion efficiency is improved by as much as 80%. UV-vi...

  2. Studies of bulk heterojunction solar cells

    Science.gov (United States)

    Cossel, Raquel; McIntyre, Max; Tzolov, Marian

    We are studying bulk heterojunction solar cells that were fabricated using a mixture of PCPDTBT and PCBM­C60. The impedance data of the cells in dark responded like a simple RC circuit. The value of the dielectric constant derived from these results is consistent with the values reported in the literature for these materials. We are showing that the parallel resistance in the equivalent circuit of linear lump elements can be interpreted using the DC current­voltage measurements. The impedance spectra under light illumination indicated the existence of additional polarization. This extra feature can be described by a model that includes a series RC circuit in parallel with the equivalent circuit for a device in dark. The physical interpretation of the additional polarization is based on photo­generated charges getting trapped in wells, which have a characteristic relaxation time corresponding to the observed break frequency in the impedance spectra. We have studied the influence of the anode and cathode interface on this phenomena, either by using different interface materials, or by depositing the metal electrode while the substate is heated.

  3. Polymer:fullerene bulk heterojunction solar cells

    Directory of Open Access Journals (Sweden)

    Jenny Nelson

    2011-10-01

    Full Text Available The efficiency of solar cells made from a conjugated polymer blended with a fullerene derivative has risen from around 1 % to over 9 % in the last ten years, making organic photovoltaic technology a viable contender for commercialization. The efficiency increases have resulted from the development of new materials with lower optical gaps, new polymer:fullerene combinations with higher charge separated state energies, and new approaches to control the blend microstructure, all driven by a qualitative understanding of the principles governing organic solar cell operation. In parallel, a device physics framework has been developed that enables the rational design of device structures and materials for improved organic photovoltaic devices. We review developments in both materials science and device physics for organic photovoltaics.

  4. Spin-cast bulk heterojunction solar cells: A dynamical investigation

    KAUST Repository

    Chou, Kang Wei

    2013-02-22

    Spin-coating is extensively used in the lab-based manufacture of organic solar cells, including most of the record-setting solution-processed cells. We report the first direct observation of photoactive layer formation as it occurs during spin-coating. The study provides new insight into mechanisms and kinetics of bulk heterojunction formation, which may be crucial for its successful transfer to scalable printing processes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Different Device Architectures for Bulk-Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Getachew Adam

    2016-08-01

    Full Text Available We report different solar cell designs which allow a simple electrical connection of subsequent devices deposited on the same substrate. By arranging so-called standard and inverted solar-cell architectures next to each other, a serial connection of the two devices can easily be realized by a single compound electrode. In this work, we tested different interfacial layer materials like polyethylenimine (PEI and PEDOT:PSS, and silver as a non-transparent electrode material. We also built organic light emitting diodes applying the same device designs demonstrating the versatility of applied layer stacks. The proposed design should allow the preparation of organic bulk-heterojunction modules with minimized photovoltaically inactive regions at the interconnection of individual devices.

  6. Study of organic solar cells with stacked bulk heterojunction structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-fang; XU Zheng; ZHAO Su-ling; ZHANG Fu-jun; LI Yan; WU Chun-yu; CHEN Yue-ning

    2008-01-01

    Organic solar cells with stacked bulk heterojunction(BHJ) are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-(2'-ethyl-hexyloxy) -1,4-phenylene vinylene] (MEH-PPV) and ZnO nanoparticles (50 nm) are mixed as the optical sense layer. Ag is used as inter-layer to connect the upper BILl cell and the lower cell. The structures are ITO/PEDOT:PSS/MEH-PPV/Ag/MEH-PPV:ZnO/Al. The open circuit voltage (Voc) of a stacked cell is about 3.7 times of that of an individual organic solar cell (ITO/PEDOT:PSS/MEH-PPV/A1). The short circuit current (Jsc) of a stacked cell is increased by about 1.6 times of that of individual one.

  7. Comparison of recombination models in organic bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Recombination in bulk-heterojunction (BHJ) organic solar cells is the key loss mechanism, and it directly affects characteristic parameters such as power conversion efficiency, short-circuit current, open-circuit voltage, and fill factor. However, which recombination mechanism dominates the loss in organic materials is unclear at present. In this work, we simulate state-of-art BHJ solar cells using five recombination models, including direct recombination, Langevin recombination, charge transfer state recombination, trap-assisted recombination, and recombination via tail. All processes are strongly dependent on charge carrier mobility and exhibit a similar recombination distribution in active layer. For high mobilities, all models present a similar behavior along with the increased mobilities, whereas, there are slight differences in open-circuit voltage between trap/tail model and other ones at lower mobilities, resulting from the interaction between photo-carriers and dark-carriers

  8. Hybrid tandem solar cells with depleted-heterojunction quantum dot and polymer bulk heterojunction subcells

    KAUST Repository

    Kim, Taesoo

    2015-10-01

    We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p-n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a VOC of 1.3V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer. © 2015.

  9. Anomalous charge storage exponents of organic bulk heterojunction solar cells.

    Science.gov (United States)

    Nair, Pradeep; Dwivedi, Raaz; Kumar, Goutam; Dept of Electrical Engineering, IIT Bombay Team

    2013-03-01

    Organic bulk heterojunction (BHJ) devices are increasingly being researched for low cost solar energy conversion. The efficiency of such solar cells is dictated by various recombination processes involved. While it is well known that the ideality factor and hence the charge storage exponents of conventional PN junction diodes are influenced by the recombination processes, the same aspects are not so well understood for organic solar cells. While dark currents of such devices typically show an ideality factor of 1 (after correcting for shunt resistance effects, if any), surprisingly, a wide range of charge storage exponents for such devices are reported in literature alluding to apparent concentration dependence for bi-molecular recombination rates. In this manuscript we critically analyze the role of bi-molecular recombination processes on charge storage exponents of organic solar cells. Our results indicate that the charge storage exponents are fundamentally influenced by the electrostatics and recombination processes and can be correlated to the dark current ideality factors. We believe that our findings are novel, and advance the state-of the art understanding on various recombination processes that dictate the performance limits of organic solar cells. The authors would like to thank the Centre of Excellence in Nanoelectronics (CEN) and the National Centre for Photovoltaic Research and Education (NCPRE), IIT Bombay for computational and financial support

  10. Molecular bulk heterojunctions: an emerging approach to organic solar cells.

    Science.gov (United States)

    Roncali, Jean

    2009-11-17

    The predicted exhaustion of fossil energy resources and the pressure of environmental constraints are stimulating an intensification of research on renewable energy sources, in particular, on the photovoltaic conversion of solar energy. In this context, organic solar cells are attracting increasing interest that is motivated by the possibility of fabricating large-area, lightweight, and flexible devices using simple techniques with low environmental impact. Organic solar cells are based on a heterojunction resulting from the contact of a donor (D) and an acceptor (A) material. Absorption of solar photons creates excitons, Coulombically bound electron-hole pairs, which diffuse to the D/A interface, where they are dissociated into free holes and electrons by the electric field. D/A heterojunctions can be created with two types of architectures, namely, bilayer heterojunction and bulk heterojunction (BHJ) solar cells. BHJ cells combine the advantages of easier fabrication and higher conversion efficiency due to the considerably extended D/A interface. Until now, the development of BHJ solar cells has been essentially based on the use of soluble pi-conjugated polymers as donor material. Intensive interdisciplinary research carried out in the past 10 years has led to an increase in the conversion efficiency of BHJ cells from 0.10 to more than 5.0%. These investigations have progressively established regioregular poly(3-hexylthiophene) (P3HT) as the standard donor material for BHJ solar cells, owing to a useful combination of optical and charge-transport properties. However, besides the limit imposed to the maximum conversion efficiency by its intrinsic electronic properties, P3HT and more generally polymers pose several problems related to the control of their structure, molecular weight, polydispersity, and purification. In this context, recent years have seen the emergence of an alternative approach based on the replacement of polydisperse polymers by soluble

  11. Spin-enhanced organic bulk heterojunction photovoltaic solar cells.

    Science.gov (United States)

    Zhang, Ye; Basel, Tek P; Gautam, Bhoj R; Yang, Xiaomei; Mascaro, Debra J; Liu, Feng; Vardeny, Z Valy

    2012-01-01

    Recently, much effort has been devoted to improve the efficiency of organic photovoltaic solar cells based on blends of donors and acceptors molecules in bulk heterojunction architecture. One of the major losses in organic photovoltaic devices has been recombination of polaron pairs at the donor-acceptor domain interfaces. Here, we present a novel method to suppress polaron pair recombination at the donor-acceptor domain interfaces and thus improve the organic photovoltaic solar cell efficiency, by doping the device active layer with spin 1/2 radical galvinoxyl. At an optimal doping level of 3 wt%, the efficiency of a standard poly(3-hexylthiophene)/1-(3-(methoxycarbonyl)propyl)-1-1-phenyl)(6,6)C(61) solar cell improves by 18%. A spin-flip mechanism is proposed and supported by magneto-photocurrent measurements, as well as by density functional theory calculations in which polaron pair recombination rate is suppressed by resonant exchange interaction between the spin 1/2 radicals and charged acceptors, which convert the polaron pair spin state from singlet to triplet.

  12. Solution processed organic bulk heterojunction tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, Steve; Neher, Dieter [Soft Matter Physics, University of Potsdam, D-14476 Potsdam (Germany)

    2011-07-01

    One of the critical issues regarding the preparation of organic tandem solar cells from solution is the central recombination contact. This contact should be highly transparent and conductive to provide high recombination currents. Moreover it should protect the 1st subcell from the solution processing of the 2nd subcell. Here, we present a systematic study of various recombination contacts in organic bulk heterojunction tandem solar cells made from blends of different polymers with PCBM. We compare solution processed recombination contacts fabricated from metal-oxides (TiO{sub 2} and ZnO) and PEDOT:PSS with evaporated recombination contacts made from thin metal layers and molybdenum-oxide. The solar cell characteristics as well as the morphology of the contacts measured by AFM and SEM are illustrated. To compare the electrical properties of the varying contacts we show measurements on single carrier devices for different contact-structures. Alongside we present the results of optical modeling of the subcells and the complete tandem device and relate these results to experimental absorption and reflection spectra of the same structures. Based on these studies, layer thicknesses were adjusted for optimum current matching and device performance.

  13. Structural order in additive processed bulk heterojunction organic solar cells

    Science.gov (United States)

    Rogers, James Thomas

    Considerable academic and industrial efforts have been dedicated to resolving scientific and technological issues associated with the fabrication of efficient plastic solar cells via solution deposition techniques. The most successful strategy used to generate solution processable devices implements a two component donor-acceptor type system composed of a (p-type) narrow bandgap conjugated polymer donor blended with a (n-type) fullerene acceptor. Due to the limited exciton diffusion lengths (~10 nm) inherent to these materials, efficient photoinduced charge generation requires heterojunction formation (i.e. donor/acceptor interfaces) in close proximity to the region of exciton generation. Maximal charge extraction therefore requires that donor and acceptor components form nanoscale phase separated percolating pathways to their respective electrodes. Devices exhibiting these structural characteristics are termed bulk heterojunction devices (BHJ). Although the BHJ architecture highlights the basic characteristics of functional donor-acceptor type organic solar cells, device optimization requires internal order within each phase and proper organization relative to the substrate in order to maximize charge transport efficiencies and minimize charge carrier recombination losses. The economic viability of BHJ solar cells hinges upon the minimization of processing costs; thus, commercially relevant processing techniques should generate optimal structural characteristics during film formation, eliminating the need for additional post deposition processing steps. Empirical optimization has shown that solution deposition using high boiling point additives (e.g. octanedithiol (ODT)) provides a simple and widely used fabrication method for maximizing the power conversion efficiencies of BHJ solar cells. This work will show using x-ray scattering that a small percentage of ODT (~2%) in chlorobenzene induces the nucleation of polymeric crystallites within 2 min of deposition

  14. Fabrication of Organic Bulk Heterojunction Solar Cells on Flexible Substrates

    Science.gov (United States)

    Calderon, Gabriel; Merced-Sanabria, Milzaida; Carradero-Santiago, Carolyn; Vedrine-Pauléus, Josee

    2015-03-01

    The active layer for the organic solar cells fabricated is composed of P3HT:PCBM, poly(3-hexylthiophene) (P3HT) as electron donor and phenyl-C61-butyric acid methyl ester(PCBM) as electron acceptor. These polymers were used due to their promising characteristics for devices such as bulk heterojunction solar devices. We used polyethylene terephthalate (PET) substrates, a highly flexible plastic, with indium tin oxide (ITO) as the transparent conducting anode for the device, and UV lithography technique to pattern the ITO; this is to facilitate multiple devices on a single substrate. The fabrication process for pattern transfer incorporates developing and etching processes. We diluted the HCl and DI water to etch out the ITO. PEDOT:PSS and active layer of P3HT:PCBM were deposited on (3.0 sq-cm) patterned of ITO/PET by spin coating method. The cathode was thermally evaporated with Al. We characterized the device using a sourcemeter. We also simulated portions of the device using PET on graphene as the substrate.

  15. Polymer-fullerene bulk-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Van Duren, J.K.J.

    2004-03-08

    In 2000 polymer:fullerene bulk-heterojunction solar cells reached power conversion efficiencies of < 1%. Improving the performance, stability, and lifetime of bulk-heterojunction solar cells requires more insight in the preparation, and operation of these devices. This thesis discusses the preparation and the morphological and electrical characterization of devices made from MDMO-PPV (poly 2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene), PCBM (1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)-methanofullerene), and their mixtures. The understanding of the influence of morphology on the device performance should aid in obtaining insight in the fundamental issues of the bulk-heterojunction concept. Furthermore, new materials are introduced in an attempt to improve performance. In chapter 2, it is shown that bulk-heterojunction solar cells made from MDMO-PPV and PCBM reach power conversion efficiencies of 2.5% under simulated solar light. It is shown for the first time that replacing the orange MDMO-PPV with a low-bandgap conjugated material results in a more red-shifted spectral response of these solar cells. Additionally, in an attempt to control the nanoscale morphology of the photoactive layer, the first example of a covalently linked donor polymer with pendant fullerenes incorporated in working solar cells is reported. The results indicated that more fundamental questions concerning the operation of the device and the influence of morphology must be addressed, before a rational improvement in device performance can be expected. Chapter 3 discusses the influence of morphology on transport in disordered organic semiconductors. Morphological investigations on films of PCBM and several PPVs are combined with the analysis of charge-carrier-mobility data. The morphological disorder observed in the PCBM films is in agreement with its charge-transport properties. Imaging individual conjugated polymer chains and aggregates on cast films with scanning force

  16. Controlling Morphology and Molecular Packing of Alkane Substituted Phthalocyanine Blend Bulk Heterojunction Solar Cells†

    OpenAIRE

    Jurow, Matthew J.; Hageman, Brian A.; DiMasi, Elaine; Nam, Chang-Yong; Pabon, Cesar; Charles T. Black; Drain, Charles Michael

    2012-01-01

    Systematic changes in the exocyclic substiution of core phthalocyanine platform tune the absorption properties to yield commercially viable dyes that function as the primary light absorbers in organic bulk heterojunction solar cells. Blends of these complementary phthalocyanines absorb a broader portion of the solar spectrum compared to a single dye, thereby increasing solar cell performance. We correlate grazing incidence small angle x-ray scattering structural data with solar cell performan...

  17. Extraction of photo-generated charge carriers from polymer-fullerene bulk heterojunction solar cells

    NARCIS (Netherlands)

    Koster, LJA; Mihailetchi, VD; Blom, PWM; Heremans, PL; Muccini, M; Hofstraat, H

    2004-01-01

    Two models describing charge extraction from insulators have been used to interpret the experimental photocurrent data of 20:80 wt% blends of poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-p-phenylene vinylene) (MDMO-PPV) and [6,6]phenyl C-61,-butyric acid methyl ester (PCBM) bulk heterojunction solar ce

  18. Determination of Physical Parameters in Organic Bulk Heterojunction Solar Cells Using a Genetic Algorithm

    Science.gov (United States)

    Nishida, Kouhei; Oka, Masaki; Hase, Hiroyuki; Naito, Hiroyoshi

    A method is presented to extract the physical parameters of illuminated organic bulk-heterojunction solar cells based on genetic algorithms and Levenberg-Marquardt method. The solar cell model is the well known single diode equivalent circuit containing four components. The voltage dependence of the photocurrent in the organic solar cells due to electron and hole drift lengths is taken into account. The applicability of the present method is demonstrated by fitting current - voltage characteristics of poly-3-hexylthiophene (P3HT) and [6,6]- phenyl-C61-butyric acid methyl ester (PCBM) bulk-heretojunction solar cells at different light intensities and annealing temperatures.

  19. Gold nanoparticles enhanced photocurrent in nanostructure-based bulk heterojunction solar cell

    Science.gov (United States)

    Long, Gen; Ching, Levine; Saqodi, Mostafa; Xu, Huizhong

    2016-04-01

    In this paper, we report a first hand study of enhanced photocurrent observed in nanostructure-based bulk heterojunction solar cell due to introduction of Au nanoparticles. The bulk heterojunction solar cell was fabricated using chemically synthesized narrow gap, IV-VI group semiconductor nanoparticles (PbS, ~3 nm), wide gap semiconductor ZnO nanowires (~1 μm length, ~50 nm diameter), and gold nanoparticles (~20 nm), by spin-coating method in N2-filled glove box. We have demonstrated that such a bulk heterojunction solar cell can be incorporated with metal nanoparticles (Au) to enhance solar device performance. Three types of solar cell devices were studied. An enhancement in the photocurrent due to introduction of Au nanoparticles was observed, compared to solar cell device without Au nanoparticles. The power conversion efficiency was also increased, possibly due to the plasmonic effects from Au nanoparticles. The fabrication procedures can be readily extended to other nanomaterial systems. Further optimization in the fabrication would be needed to realize high-efficient, stable solar cell devices.

  20. Morphology versus Vertical Phase Segregation in Solvent Annealed Small Molecule Bulk Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Alexander Kovalenko

    2015-01-01

    Full Text Available The deep study of solvent annealed small molecules bulk heterojunction organic solar cells based on DPP(TBFu2 : PC60BM blend is carried out. To reveal the reason of the solvent annealing advantage over the thermal one, capacitance-voltage measurements were applied. It was found that controlling the vertical phase segregation in the solar cells a high fullerene population in the vicinity of the cathode could be achieved. This results in increase of the shunt resistance of the cell, thus improving the light harvesting efficiency.

  1. Incomplete Exciton Harvesting from Fullerenes in Bulk Heterojunction Solar Cells

    KAUST Repository

    Burkhard, George F.

    2009-12-09

    We investigate the internal quantum efficiencies (IQEs) of high efficiency poly-3-hexylthiophene:[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells and find them to be lower at wavelengths where the PCBM absorbs. Because the exciton diffusion length in PCBM is too small, excitons generated in PCBM decay before reaching the donor-acceptor interface. This result has implications for most state of the art organic solar cells, since all of the most efficient devices use fullerenes as electron acceptors. © 2009 American Chemical Society.

  2. Nanocomposite-Based Bulk Heterojunction Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Bich Phuong Nguyen

    2014-01-01

    Full Text Available Photovoltaic devices based on nanocomposites composed of conjugated polymers and inorganic nanocrystals show promise for the fabrication of low-cost third-generation thin film photovoltaics. In theory, hybrid solar cells can combine the advantages of the two classes of materials to potentially provide high power conversion efficiencies of up to 10%; however, certain limitations on the current within a hybrid solar cell must be overcome. Current limitations arise from incompatibilities among the various intradevice interfaces and the uncontrolled aggregation of nanocrystals during the step in which the nanocrystals are mixed into the polymer matrix. Both effects can lead to charge transfer and transport inefficiencies. This paper highlights potential strategies for resolving these obstacles and presents an outlook on the future directions of this field.

  3. Solvent additive effects on small molecule crystallization in bulk heterojunction solar cells probed during spin casting

    KAUST Repository

    Pérez, Louis A.

    2013-09-04

    Solvent additive processing can lead to drastic improvements in the power conversion efficiency (PCE) in solution processable small molecule (SPSM) bulk heterojunction solar cells. In situ grazing incidence wide-angle X-ray scattering is used to investigate the kinetics of crystallite formation during and shortly after spin casting. The additive is shown to have a complex effect on structural evolution invoking polymorphism and enhanced crystalline quality of the donor SPSM. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Recombination lifetime of free polarons in polymer/fullerene bulk heterojunction solar cells

    Science.gov (United States)

    Li, Kejia; Li, Lijun; Campbell, Joe C.

    2012-02-01

    The recombination lifetime of free polarons was measured using three different methods: electrical field-dependent photoresponse, transient photoconductivity, and forward-to-zero bias transient-current response. The average free polaron recombination lifetime is estimated to be a few microseconds for poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) solar cells. The competition between sweep-out by the internal field and the loss of photogenerated carriers by recombination is analyzed. The short-circuit free polaron collection efficiency for P3HT:PCBM bulk heterojunction material was determined to be in the range of 80% to 90%.

  5. Self-assembled, nanowire network electrodes for depleted bulk heterojunction solar cells

    KAUST Repository

    Lan, Xinzheng

    2013-01-06

    Herein, a solution-processed, bottom-up-fabricated, nanowire network electrode is developed. This electrode features a ZnO template which is converted into locally connected, infiltratable, TiO2 nanowires. This new electrode is used to build a depleted bulk heterojunction solar cell employing hybrid-passivated colloidal quantum dots. The new electrode allows the application of a thicker, and thus more light-absorbing, colloidal quantum dot active layer, from which charge extraction of an efficiency comparable to that obtained from a thinner, planar device could be obtained. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Self-assembly Columnar Structure in Active Layer of Bulk Heterojunction Solar Cell

    Science.gov (United States)

    Pan, Cheng; Segui, Jennifer; Yu, Yingjie; Li, Hongfei; Akgun, Bulent; Satijia, Sushil. K.; Gersappe, Dilip; Nam, Chang-Yong; Rafailovich, Miriam

    2012-02-01

    Bulk Heterojunction (BHJ) polymer solar cells are an area of intense interest due to their flexibility and relatively low cost. However, due to the disordered inner structure in active layer, the power conversion efficiency of BHJ solar cell is relatively low. Our research provides the method to produce ordered self-assembly columnar structure within active layer of bulk heterojunction (BHJ) solar cell by introducing polystyrene (PS) into the active layer. The blend thin film of polystyrene, poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) at different ratio are spin coated on substrate and annealed in vacuum oven for certain time. Atomic force microscopy (AFM) images show uniform phase segregation on the surface of polymer blend thin film and highly ordered columnar structure is then proven by etching the film with ion sputtering. TEM cross-section technology is also used to investigate the column structure. Neutron reflectometry was taken to establish the confinement of PCBM at the interface of PS and P3HT. The different morphological structures formed via phase segregation will be correlated with the performance of the PEV cells to be fabricated at the BNL-CFN.

  7. Development of Efficient and Stable Inverted Bulk Heterojunction (BHJ Solar Cells Using Different Metal Oxide Interfaces

    Directory of Open Access Journals (Sweden)

    Ivan Litzov

    2013-12-01

    Full Text Available Solution-processed inverted bulk heterojunction (BHJ solar cells have gained much more attention during the last decade, because of their significantly better environmental stability compared to the normal architecture BHJ solar cells. Transparent metal oxides (MeOx play an important role as the dominant class for solution-processed interface materials in this development, due to their excellent optical transparency, their relatively high electrical conductivity and their tunable work function. This article reviews the advantages and disadvantages of the most common synthesis methods used for the wet chemical preparation of the most relevant n-type- and p-type-like MeOx interface materials consisting of binary compounds AxBy. Their performance for applications as electron transport/extraction layers (ETL/EEL and as hole transport/extraction layers (HTL/HEL in inverted BHJ solar cells will be reviewed and discussed.

  8. Direct determination of defect density of states in organic bulk heterojunction solar cells

    Science.gov (United States)

    Verma, Upkar K.; Tripathi, Durgesh C.; Mohapatra, Y. N.

    2016-09-01

    The measurement of the occupied trap density of states (DOS) is important for optimization of organic bulk heterojunction solar cells. We demonstrate a direct method for obtaining it from the trap related peak in capacitance-voltage characteristics under different levels of illumination, and its correlation with the dark current density-voltage characteristics. We use the method to measure the parameters of DOS, occupied trap distribution, and its temperature dependence for poly(3-hexathiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) based solar cells. The total occupied trap concentration is approximately 7 × 1015 cm-3 with a standard deviation for a truncated Gaussian distribution varying between 32 and 44 meV in the temperature range of 310-270 K within a total Gaussian DOS with a standard deviation of 92 meV.

  9. Plasmon-enhanced polymer bulk heterojunction solar cells with solution-processable Ag nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YAN Qi-qi; QIN Wen-jing; WANG Chao; SONG Peng-fei; DING Guo-jing; YANG Li-ying; YIN Shou-gen

    2011-01-01

    We report the plasmon-enhanced polymer bulk-heterojunction solar cells with Ag nanoparticles (AgNPs) obtained via chemical method.Here,the AgNPs films with different particle densities are introduced between the poly (3,4-ethylene dioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) buffer layer and the poly (3-hexythiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) layer.By improving the optical absorption of the active layer owing to the localized surface plasmons,the power conversion efficiency of the solar cells is increased compared with the control device.It is shown that the efficiency of the device increases with the density of AgNPs.For the device employing higher density,the resulted power conversion efficiency is found to increase from 2.89% to 3.38%,enhanced by 16.96%.

  10. Interfacial Characteristics of Efficient Bulk Heterojunction Solar Cells Fabricated on MoOx Anode Interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Jasieniak, Jacek J.; Treat, Neil D.; McNeill, Christopher R.; Tremolet de Villers, Bertrand J.; Gaspera, Enrico Della; Chabinyc, Michael L.

    2016-05-25

    The role of the interface between an MoOx anode interlayer and a polymer:fullerene bulk heterojunction is investigated. Processing differences in the MoOx induce large variations in the vertical stratification of the bulk heterojunction films. These variations are found to be inconsistent in predicting device performance, with a much better gauge being the quantity of polymer chemisorbed to the anode interlayer.

  11. Ordered Nanopillar Structured Electrodes for Depleted Bulk Heterojunction Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Kramer, Illan J.

    2012-03-30

    A bulk heterojunction of ordered titania nanopillars and PbS colloidal quantum dots is developed. By using a pre-patterned template, an ordered titania nanopillar matrix with nearest neighbours 275 nm apart and height of 300 nm is fabricated and subsequently filled in with PbS colloidal quantum dots to form an ordered depleted bulk heterojunction exhibiting power conversion efficiency of 5.6%. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Charge transport and recombination dynamics in organic bulk heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Andreas

    2011-08-02

    The charge transport in disordered organic bulk heterojunction (BHJ) solar cells is a crucial process affecting the power conversion efficiency (PCE) of the solar cell. With the need of synthesizing new materials for improving the power conversion efficiency of those cells it is important to study not only the photophysical but also the electrical properties of the new material classes. Thereby, the experimental techniques need to be applicable to operating solar cells. In this work, the conventional methods of transient photoconductivity (also known as ''Time-of-Flight'' (TOF)), as well as the transient charge extraction technique of ''Charge Carrier Extraction by Linearly Increasing Voltage'' (CELIV) are performed on different organic blend compositions. Especially with the latter it is feasible to study the dynamics - i.e. charge transport and charge carrier recombination - in bulk heterojunction (BHJ) solar cells with active layer thicknesses of 100-200 nm. For a well performing organic BHJ solar cells the morphology is the most crucial parameter finding a trade-off between an efficient photogeneration of charge carriers and the transport of the latter to the electrodes. Besides the morphology, the nature of energetic disorder of the active material blend and its influence on the dynamics are discussed extensively in this work. Thereby, the material system of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C{sub 61}butyric acid methyl ester (PC{sub 61}BM) serves mainly as a reference material system. New promising donor or acceptor materials and their potential for application in organic photovoltaics are studied in view of charge dynamics and compared with the reference system. With the need for commercialization of organic solar cells the question of the impact of environmental conditions on the PCE of the solar cells raises. In this work, organic BHJ solar cells exposed to synthetic air for finite duration are

  13. Utilizing Energy Transfer in Binary and Ternary Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Feron, Krishna; Cave, James M; Thameel, Mahir N; O'Sullivan, Connor; Kroon, Renee; Andersson, Mats R; Zhou, Xiaojing; Fell, Christopher J; Belcher, Warwick J; Walker, Alison B; Dastoor, Paul C

    2016-08-17

    Energy transfer has been identified as an important process in ternary organic solar cells. Here, we develop kinetic Monte Carlo (KMC) models to assess the impact of energy transfer in ternary and binary bulk heterojunction systems. We used fluorescence and absorption spectroscopy to determine the energy disorder and Förster radii for poly(3-hexylthiophene-2,5-diyl), [6,6]-phenyl-C61-butyric acid methyl ester, 4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (DIBSq), and poly(2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3',2'-h][1,5]naphthyridine-5,10-dione). Heterogeneous energy transfer is found to be crucial in the exciton dissociation process of both binary and ternary organic semiconductor systems. Circumstances favoring energy transfer across interfaces allow relaxation of the electronic energy level requirements, meaning that a cascade structure is not required for efficient ternary organic solar cells. We explain how energy transfer can be exploited to eliminate additional energy losses in ternary bulk heterojunction solar cells, thus increasing their open-circuit voltage without loss in short-circuit current. In particular, we show that it is important that the DIBSq is located at the electron donor-acceptor interface; otherwise charge carriers will be trapped in the DIBSq domain or excitons in the DIBSq domains will not be able to dissociate efficiently at an interface. KMC modeling shows that only small amounts of DIBSq (energy transfer.

  14. Utilizing Energy Transfer in Binary and Ternary Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Feron, Krishna; Cave, James M; Thameel, Mahir N; O'Sullivan, Connor; Kroon, Renee; Andersson, Mats R; Zhou, Xiaojing; Fell, Christopher J; Belcher, Warwick J; Walker, Alison B; Dastoor, Paul C

    2016-08-17

    Energy transfer has been identified as an important process in ternary organic solar cells. Here, we develop kinetic Monte Carlo (KMC) models to assess the impact of energy transfer in ternary and binary bulk heterojunction systems. We used fluorescence and absorption spectroscopy to determine the energy disorder and Förster radii for poly(3-hexylthiophene-2,5-diyl), [6,6]-phenyl-C61-butyric acid methyl ester, 4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (DIBSq), and poly(2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3',2'-h][1,5]naphthyridine-5,10-dione). Heterogeneous energy transfer is found to be crucial in the exciton dissociation process of both binary and ternary organic semiconductor systems. Circumstances favoring energy transfer across interfaces allow relaxation of the electronic energy level requirements, meaning that a cascade structure is not required for efficient ternary organic solar cells. We explain how energy transfer can be exploited to eliminate additional energy losses in ternary bulk heterojunction solar cells, thus increasing their open-circuit voltage without loss in short-circuit current. In particular, we show that it is important that the DIBSq is located at the electron donor-acceptor interface; otherwise charge carriers will be trapped in the DIBSq domain or excitons in the DIBSq domains will not be able to dissociate efficiently at an interface. KMC modeling shows that only small amounts of DIBSq (<5% by weight) are needed to achieve substantial performance improvements due to long-range energy transfer. PMID:27456294

  15. Criteria for validating polaron pair dissociation in polymer-fullerene bulk heterojunction solar cells

    Science.gov (United States)

    Inche Ibrahim, M. L.

    2016-04-01

    The dissociation of polaron pairs into free charge carriers in organic bulk heterojunction solar cells is a fundamental step in generating photocurrent and is still in debate. In this study, we propose two simple criteria that can be used to test the validity of any polaron pair dissociation model for polymer-fullerene bulk heterojunction solar cells. The first criterion states that the ratio of the bimolecular recombination current density to the maximum photocurrent density should increase as a function of applied voltage. The second criterion states that the ratio of the bimolecular recombination current density to the maximum photocurrent density at short circuit should not be larger than 1. We apply these criteria to test the validity of the widely used Onsager-Braun model by using the experimental current-voltage data of poly[2-methoxy-5-(3'-7'-dimethyloctyloxy)-p-phenylene vinylene] (OC1C10-PPV) and [6,6]-phenyl C61-butyric acid methylester (PCBM) based solar cells. We find that our numerical analysis is not suitable to employ these criteria. Our analytical analysis, on the other hand, clearly demonstrates that the Onsager-Braun model simply cannot fulfill the first criteria. The reason is because the polaron pair dissociation given by the Onsager-Braun model is too strongly influenced by the electric field (i.e., decreases too rapidly as the electric field decreases). The analysis provides a further evidence against the widely used Onsager-Braun model. The proposed criteria can help us to determine the correct model for polaron pair dissociation by serving as a guideline on how strongly the electric field is allowed to influence the polaron pair dissociation.

  16. Deuterium isotope effect on bulk heterojunction solar cells. Enhancement of organic photovoltaic performances using monobenzyl substituted deuteriofullerene acceptors.

    Science.gov (United States)

    Lu, Shirong; Jin, Tienan; Yasuda, Takeshi; Si, Weili; Oniwa, Kazuaki; Alamry, Khalid A; Kosa, Samia A; Asiri, Abdullah Mohamed; Han, Liyuan; Yamamoto, Yoshinori

    2013-11-15

    A series of novel monobenzyl-substituted deuteriofullerenes (BnDCs) were synthesized efficiently through Co-catalyzed selective monofunctionalization of C60. Bulk heterojunction solar cells, based on poly(3-hexylthiophene) as the donor and BnDCs as the acceptors, exhibited higher photovoltaic performances as compared to the corresponding protonated BnHCs devices.

  17. Analytical Model for Voltage-Dependent Photo and Dark Currents in Bulk Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Mesbahus Saleheen

    2016-05-01

    Full Text Available A physics-based explicit mathematical model for the external voltage-dependent forward dark current in bulk heterojunction (BHJ organic solar cells is developed by considering Shockley-Read-Hall (SRH recombination and solving the continuity equations for both electrons and holes. An analytical model for the external voltage-dependent photocurrent in BHJ organic solar cells is also proposed by incorporating exponential photon absorption, dissociation efficiency of bound electron-hole pairs (EHPs, carrier trapping, and carrier drift and diffusion in the photon absorption layer. Modified Braun’s model is used to compute the electric field-dependent dissociation efficiency of the bound EHPs. The overall net current is calculated considering the actual solar spectrum. The mathematical models are verified by comparing the model calculations with various published experimental results. We analyze the effects of the contact properties, blend compositions, charge carrier transport properties (carrier mobility and lifetime, and cell design on the current-voltage characteristics. The power conversion efficiency of BHJ organic solar cells mostly depends on electron transport properties of the acceptor layer. The results of this paper indicate that improvement of charge carrier transport (both mobility and lifetime and dissociation of bound EHPs in organic blend are critically important to increase the power conversion efficiency of the BHJ solar cells.

  18. Bulk heterojunction perovskite-PCBM solar cells with high fill factor

    Science.gov (United States)

    Chiang, Chien-Hung; Wu, Chun-Guey

    2016-03-01

    An inverted bulk heterojunction perovskite-PCBM solar cell with a high fill factor of 0.82 and a power conversion efficiency of up to 16.0% was fabricated by a low-temperature two-step solution process. The cells exhibit no significant photocurrent hysteresis and their high short-circuit current density, fill factor and efficiency are attributed to the advantageous properties of the active layer, such as its high conductivity and the improved mobility and diffusion length of charge carriers. In particular, PCBM plays a critical role in improving the quality of the light-absorbing layer by filling pinholes and vacancies between perovskite grains, resulting in a film with large grains and fewer grain boundaries.

  19. Pentacene–fullerene bulk-heterojunction solar cell: A computational study

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Anup [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India); Sarkar, Sunandan [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India); Dept. of Physical Chemistry, Palacký University, Olomouc (Czech Republic); Pal, Sougata [Department of Chemistry, University of Gour Banga, Malda 732103 (India); Sarkar, Pranab, E-mail: pranab.sarkar@visva-bharati.ac.in [Department of Chemistry, Visva-Bharati University, Santiniketan 731235 (India)

    2015-06-12

    We perform DFT/TDDFT calculations to study the optoelectronic properties of some pentacene-based organic molecules and their derivatives, which can serve as donor moiety when blended with fullerene acceptors in the bulk-heterojunction solar cell model. We are motivated by a recent experiment in which an unoptimized device was shown to have a good photovoltaic performance and we aim to further improve the efficiency of this device. We try to optimize the photovoltaic properties on the basis of a quantum-mechanical calculation of the frontier energy levels and of the absorption properties of individual molecules and of the molecule–fullerine composite. - Highlights: • Optoelectronic properties of pentacene–fullerene nanocomposites are presented. • Photovoltaic properties of the nanocomposites are predicted. • DFT/TDDFT results are in well agreement with available experimental results. • Calculated results give a direction for optimizing device performance.

  20. Effect of annealing on bulk heterojunction organic solar cells based on copper phthalocyanine and perylene derivative

    KAUST Repository

    Kim, Inho

    2012-02-01

    We investigated the effects of annealing on device performances of bulk heterojunction organic solar cells based on copper phthalocyanine (CuPc) and N,N′-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C6). Blended films of CuPc and PTCDI-C6 with annealing at elevated temperature were characterized by measuring optical absorption, photoluminescence, and X-ray diffraction. Enhanced molecular ordering and increments in domain sizes of donor and acceptor for the blended films were observed, and their influences on device performances were discussed. Annealing led to substantial improvements in photocurrent owing to enhanced molecular ordering and formation of percolation pathways. © 2011 Elsevier B.V. All rights reserved.

  1. Neat C₇₀-based bulk-heterojunction polymer solar cells with excellent acceptor dispersion.

    Science.gov (United States)

    Gasparini, Nicola; Righi, Sara; Tinti, Francesca; Savoini, Alberto; Cominetti, Alessandra; Po, Riccardo; Camaioni, Nadia

    2014-12-10

    The replacement of common fullerene derivatives with neat-C70 could be an effective approach to restrain the costs of organic photovoltaics and increase their sustainability. In this study, bulk-heterojunction solar cells made of neat-C70 and low energy-gap conjugated polymers, PTB7 and PCDTBT, are thoroughly investigated and compared. Upon replacing PC70BM with C70, the mobility of positive carriers in the donor phase is roughly reduced by 1 order of magnitude, while that of electrons is only slightly modified. It is shown that the main loss mechanism of the investigated neat-C70 solar cells is a low mobility-lifetime product. Nevertheless, PCDTBT:C70 devices undergo a limited loss of 7.5%, compared to the reference PCDTBT:PC70BM cells, reaching a record efficiency (4.44%) for polymer solar cells with unfunctionalized fullerenes. The moderate efficiency loss of PCDTBT:C70 devices, due to an unexpected excellent miscibility of PCDTBT:C70 blends, demonstrates that efficient solar cells made of neat-fullerene are possible. The efficient dispersion of C70 in the PCDTBT matrix is attributed to an interaction between fullerene and the carbazole unit of the polymer.

  2. Study of a ternary blend system for bulk heterojunction thin film solar cells

    Science.gov (United States)

    Ahmad, Zubair; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

    2016-08-01

    In this research, we report a bulk heterojunction (BHJ) solar cell consisting of a ternary blend system. Poly(3-hexylthiophene) P3HT is used as a donor and [6,6]-phenyl C61-butyric acid methylester (PCBM) plays the role of acceptor whereas vanadyl 2,9,16,23-tetraphenoxy-29H, 31H-phthalocyanine (VOPcPhO) is selected as an ambipolar transport material. The materials are selected and assembled in such a fashion that the generated charge carriers could efficiently be transported rightwards within the blend. The organic BHJ solar cells consist of ITO/PEDOT:PSS/ternary BHJ blend/Al structure. The power conversion efficiencies of the ITO/ PEDOT:PSS/P3HT:PCBM/Al and ITO/PEDOT:PSS/ P3HT:PCBM:VOPcPhO/Al solar cells are found to be 2.3% and 3.4%, respectively. This publication was made possible by PDRA (Grant No. PDRA1-0117-14109) from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors.

  3. Sodium chloride methanol solution spin-coating process for bulk-heterojunction polymer solar cells

    Science.gov (United States)

    Liu, Tong-Fang; Hu, Yu-Feng; Deng, Zhen-Bo; Li, Xiong; Zhu, Li-Jie; Wang, Yue; Lv, Long-Feng; Wang, Tie-Ning; Lou, Zhi-Dong; Hou, Yan-Bing; Teng, Feng

    2016-08-01

    The sodium chloride methanol solution process is conducted on the conventional poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) polymer bulk heterojunction solar cells. The device exhibits a power conversion efficiency of up to 3.36%, 18% higher than that of the device without the solution process. The measurements of the active layer by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS) indicate a slight phase separation in the vertical direction and a sodium chloride distributed island-like interface between the active layer and the cathode. The capacitance–voltage (C–V) and impedance spectroscopy measurements prove that the sodium chloride methanol process can reduce the electron injection barrier and improve the interfacial contact of polymer solar cells. Therefore, this one-step solution process not only optimizes the phase separation in the active layers but also forms a cathode buffer layer, which can enhance the generation, transport, and collection of photogenerated charge carriers in the device simultaneously. This work indicates that the inexpensive and non-toxic sodium chloride methanol solution process is an efficient one-step method for the low cost manufacturing of polymer solar cells. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. 2014JBZ009) and the National Natural Science Foundation of China (Grant Nos. 61274063, 61377028, 61475014, and 61475017).

  4. Performance improvement of organic bulk heterojunction solar cells by using dihydroxybenzene as additive

    Institute of Scientific and Technical Information of China (English)

    YAO Cong; YANG Li-ying; WANG Ya-ling; QIN Wen-jing; YIN Shou-gen; ZHANG Feng-ling

    2011-01-01

    We report the enhanced performance of organic solar cells (OSCs) based on regioregular poly(3-hexylthiophene) (P3HT)and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend by using dihydroxybenzene as additive in the active layer. The effect of the content of the additives on electrical characteristics of the device is studied. The device with 0.2 wt% dihydroxybenzene additive achieves the best power conversion efficiency (PCE) of 4.58% with Jsc of 12.5 mA/cm2, Voc of 0.65 V, and FF of 66.6% under simulated solar illumination of AM 1.5G (100 mW/cm2), compared with the control device with PCE of 3.39% (35% improvement compared with the control device). The XRD measurement reveals that the addition of additives induces the crystallization of P3HT and establishes good inter-network to increase the contact area of donor and acceptor, and then helps charge to be effectively transferred to the electrode to reduce the chance of recombination. All evidences indicate that the dihydroxybenzene is likely to be a promising new type additive that can enhance the performance of organic bulk heterojunction solar cells.

  5. Sodium chloride methanol solution spin-coating process for bulk-heterojunction polymer solar cells

    Science.gov (United States)

    Liu, Tong-Fang; Hu, Yu-Feng; Deng, Zhen-Bo; Li, Xiong; Zhu, Li-Jie; Wang, Yue; Lv, Long-Feng; Wang, Tie-Ning; Lou, Zhi-Dong; Hou, Yan-Bing; Teng, Feng

    2016-08-01

    The sodium chloride methanol solution process is conducted on the conventional poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) polymer bulk heterojunction solar cells. The device exhibits a power conversion efficiency of up to 3.36%, 18% higher than that of the device without the solution process. The measurements of the active layer by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS) indicate a slight phase separation in the vertical direction and a sodium chloride distributed island-like interface between the active layer and the cathode. The capacitance-voltage (C-V) and impedance spectroscopy measurements prove that the sodium chloride methanol process can reduce the electron injection barrier and improve the interfacial contact of polymer solar cells. Therefore, this one-step solution process not only optimizes the phase separation in the active layers but also forms a cathode buffer layer, which can enhance the generation, transport, and collection of photogenerated charge carriers in the device simultaneously. This work indicates that the inexpensive and non-toxic sodium chloride methanol solution process is an efficient one-step method for the low cost manufacturing of polymer solar cells. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. 2014JBZ009) and the National Natural Science Foundation of China (Grant Nos. 61274063, 61377028, 61475014, and 61475017).

  6. An analytical model for analyzing the current-voltage characteristics of bulk heterojunction organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Arnab, Salman M.; Kabir, M. Z., E-mail: kabir@encs.concordia.ca [Department of Electrical and Computer Engineering, Concordia University, 1455 Blvd. de Maisonneuve West, Montreal, Quebec H3G 1M8 (Canada)

    2014-01-21

    An analytical model for analyzing the current-voltage (J-V) characteristics of bulk heterojunction (BHJ) organic solar cells is developed by incorporating exponential photon absorption, dissociation efficiency of bound electron-hole pairs (EHPs), carrier trapping, and carrier drift and diffusion in the photon absorption layer. Modified Braun's model is used to compute the electric field-dependent dissociation efficiency of the bound EHPs. The charge carrier concentrations and hence the photocurrent are calculated by solving the carrier continuity equation for both holes and electrons in the organic layer. The overall load current is calculated considering the actual solar spectrum and voltage dependent forward dark current. The model is verified by published experimental results. The efficiency of the P3HT:PCBM based solar cells critically depends on the dissociation of bound EHPs. On the other hand, cells made of a blend of the conjugated polymer (PCDTBT) with the soluble fullerene derivative (PCBM) show nearly unity dissociation efficiency, and their cell efficiency strongly depends on the charge collection efficiency. The effects of carrier lifetimes on the performance of PCDTBT solar cells have also been studied. The model is also used to investigate the effect of titanium oxide (TiO{sub x}) layer (at the back contact) on the J-V characteristics of PCDTBT solar cells. The results of this paper indicate that improvement of charge carrier transport in PCDTBT:PCBM blend and dissociation of bound EHPs in P3HT:PCBM blend are extremely important to increase the power conversion efficiency of the respective BHJ solar cells.

  7. A Quantum Chemical Study on Polythiophenes Derivatives as Donor Materials in Bulk-heterojunction Polymer Solar Cell

    Directory of Open Access Journals (Sweden)

    Bushra Mohamed Omer

    2012-09-01

    Full Text Available For the optimum design of the donor and acceptor materials in polymer solar cells, it is very important to do a theoretical calculation for the energy levels and energy gaps. In this work we used the semiempirical method Austin Model1 (AM1 to investigate the Higher Occupied Molecular Orbital (HOMO and Lower Unoccupied Molecular Orbital (LUMO of polythiophenes derivatives/fullerenes combination (bulk heterojunction polymer solar cells. The overestimation on the HOMO and LUMO values was corrected by using experimental data from literature as criteria of correctness. Using our correction method, a reasonable linear relationship between the computed energy band gaps of polythiophenes derivatives and the experimental band gaps were found. The corrected HOMO and LUMO energies of polythiophenes derivatives match well with the experimental one. This method can serve as a road map inorder to design and synthesis appropriate combination of polythiophenes derivatives/fullerenes for bulk heterojunction solar cells.

  8. Vacuum-free processed bulk heterojunction solar cells with E-GaIn cathode as an alternative to Al electrode

    International Nuclear Information System (INIS)

    In this paper, the photovoltaic characteristics of bulk heterojunction solar cells employing an eutectic gallium–indium (EGaIn) alloy as a top metal contact which was coated by a simple and inexpensive brush-painting was investigated. The overall solar cell fabrication procedure was vacuum-free. As references, regular organic bulk heterojunction solar cells employing thermally evaporated Aluminum as a top metal contact were also fabricated. Inserting the ZnO layer between the active layer and the cathode electrodes (Al and EGaIn) improved the photovoltaic performance of the herein investigated devices. The power conversion efficiencies with and without EGaIn top electrodes were rather comparable. Hence, we have shown that the EGaIn, which is liquid at room temperature, can be used as a cathode. It allows an easy and rapid device fabrication that can be implemented through a vacuum free process. (paper)

  9. Modeling organic bulk-heterojunction solar cells: Parameter stability and photocurrent transients

    Science.gov (United States)

    Hausermann, Roger; Knapp, Evelyne; Moos, Michael; Reinke, Nils; Flatz, Thomas; Ruhstaller, Beat

    2010-03-01

    An opto-electronic device model for organic bulk-heterojunction solar cells is presented (setfos by fluxim). First, the optical in-coupling into a multilayer stack is calculated. From the photon absorption profile a charge-transfer (CT) exciton profile is derived. These CT-excitons are then dissociated according to the Onsager-Braun model. The resulting motion of electrons and holes is modeled considering both drift and diffusion. We analyze measurements on P3HT:PCBM based solar cells and derive a set of parameter values, including values for CT-exciton dissociation. The experiments are well described and the stability of the parameters under various conditions is tested. This includes the simulation of current-voltage curves, the dependence of the short-circuit current on the layer thickness, and transient photo-currents. It is shown that simulating the transient photo-current is particularly helpful in determining the values of electron and hole mobility. This highlights the need to measure transient photo-currents to extract device parameters such as mobilities and CT-exciton dissociation constants.[4pt] J. Appl. Phys. 106, 104507 (2009)

  10. Optical modeling of bulk-heterojunction organic solar cells based on squarine dye as electron donor

    International Nuclear Information System (INIS)

    The potentiality of a squarine dye (Sq1) for using as electron donor component in bulk heterojunction organic solar cells (BHJ) has been studied from the optical point of view. The soluble n-type fullerene, (6,6)-phenyl C61 butyric acid methyl ester (PC61MB) was chosen as acceptor. Optical modelling based on transfer matrix method was carried out to predict and improve photovoltaic performance of a BHJ device with blended Sq1/PC61MB active layer. The dependence of the absorption and the calculated maximum short circuit photocurrent (Jscmax) on the thickness of the active layer (dact), was investigated for two weight ratios of Sq1 and PC61MB. Thus, the optimal dact was calculated to be about 100 nm, which provides an efficient overlapping of the total absorption with solar spectrum in the range between 580 and 900 nm. Besides, it is found that the insertion of ZnO or C60 spacer layer shifts Jscmax peak to lower dact and significantly enhances Jscmax for active layers with dact < 50 nm, which is mainly due to improved light absorption by a factor of 5 to 10. Simultaneously, for dact <100 nm the optical effect of inserted PEDOT:PSS hole transporting layer is negligible

  11. Optical modeling of bulk-heterojunction organic solar cells based on squarine dye as electron donor

    Science.gov (United States)

    Kitova, S.; Stoyanova, D.; Dikova, J.; Kandinska, M.; Vasilev, A.; Angelova, S.

    2014-12-01

    The potentiality of a squarine dye (Sq1) for using as electron donor component in bulk heterojunction organic solar cells (BHJ) has been studied from the optical point of view. The soluble n-type fullerene, (6,6)-phenyl C61 butyric acid methyl ester (PC61MB) was chosen as acceptor. Optical modelling based on transfer matrix method was carried out to predict and improve photovoltaic performance of a BHJ device with blended Sq1/PC61MB active layer. The dependence of the absorption and the calculated maximum short circuit photocurrent (Jscmax) on the thickness of the active layer (dact), was investigated for two weight ratios of Sq1 and PC61MB. Thus, the optimal dact was calculated to be about 100 nm, which provides an efficient overlapping of the total absorption with solar spectrum in the range between 580 and 900 nm. Besides, it is found that the insertion of ZnO or C60 spacer layer shifts Jscmax peak to lower dact and significantly enhances Jscmax for active layers with dact < 50 nm, which is mainly due to improved light absorption by a factor of 5 to 10. Simultaneously, for dact <100 nm the optical effect of inserted PEDOT:PSS hole transporting layer is negligible.

  12. Structure–property relationships of oligothiophene–isoindigo polymers for efficient bulk-heterojunction solar cells

    KAUST Repository

    Ma, Zaifei

    2014-01-01

    A series of alternating oligothiophene (nT)-isoindigo (I) copolymers (PnTI) were synthesized to investigate the influence of the oligothiophene block length on the photovoltaic (PV) properties of PnTI:PCBM bulk-heterojunction blends. Our study indicates that the number of thiophene rings (n) in the repeating unit alters both polymer crystallinity and polymer-fullerene interfacial energetics, which results in a decreasing open-circuit voltage (Voc) of the solar cells with increasing n. The short-circuit current density (Jsc) of P1TI:PCBM devices is limited by the absence of a significant driving force for electron transfer. Instead, blends based on P5TI and P6TI feature large polymer domains, which limit charge generation and thus Jsc. The best PV performance with a power conversion efficiency of up to 6.9% was achieved with devices based on P3TI, where a combination of a favorable morphology and an optimal interfacial energy level offset ensures efficient exciton separation and charge generation. The structure-property relationship demonstrated in this work would be a valuable guideline for the design of high performance polymers with small energy losses during the charge generation process, allowing for the fabrication of efficient solar cells that combine a minimal loss in Voc with a high Jsc. © 2014 The Royal Society of Chemistry.

  13. Electron and Hole Transport Layers: Their Use in Inverted Bulk Heterojunction Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Sandro Lattante

    2014-03-01

    Full Text Available Bulk heterojunction polymer solar cells (BHJ PSCs are very promising organic-based devices for low-cost solar energy conversion, compatible with roll-to-roll or general printing methods for mass production. Nevertheless, to date, many issues should still be addressed, one of these being the poor stability in ambient conditions. One elegant way to overcome such an issue is the so-called “inverted” BHJ PSC, a device geometry in which the charge collection is reverted in comparison with the standard geometry device, i.e., the electrons are collected by the bottom electrode and the holes by the top electrode (in contact with air. This reverted geometry allows one to use a high work function top metal electrode, like silver or gold (thus avoiding its fast oxidation and degradation, and eliminates the need of a polymeric hole transport layer, typically of an acidic nature, on top of the transparent metal oxide bottom electrode. Moreover, this geometry is fully compatible with standard roll-to-roll manufacturing in air and is less demanding for a good post-production encapsulation process. To date, the external power conversion efficiencies of the inverted devices are generally comparable to their standard analogues, once both the electron transport layer and the hole transport layer are fully optimized for the particular device. Here, the most recent results on this particular optimization process will be reviewed, and a general outlook regarding the inverted BHJ PSC will be depicted.

  14. The effect of morphology upon mobility : Implications for bulk heterojunction solar cells with nonuniform blend morphology

    NARCIS (Netherlands)

    Groves, C.; Koster, L. J. A.; Greenham, N. C.

    2009-01-01

    We use a Monte Carlo model to predict the effect of composition, domain size, and energetic disorder upon the mobility of carriers in an organic donor-acceptor blend. These simulations show that, for the changes in local morphology expected within the thickness of a typical bulk heterojunction photo

  15. Ferroelectric field effect of the bulk heterojunction in polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meng; Ma, Heng, E-mail: hengma@henannu.edu.cn; Liu, Hairui; Jiang, Yurong [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China); Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); Niu, Heying; Amat, Adil [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007 (China)

    2014-06-23

    A ferroelectric field effect in the bulk heterojunction was found when an external electric field (EEF) was applied on the active layer of polymer solar cells (PSCs) during the annealing process of the active layer spin-coated with poly(3-hexylthiophene):[6,6]-phenyl-C{sub 61} butyric acid methyl ester. For one direction field, the short circuit current density of PSCs was improved from 7.2 to 8.0 mA/cm{sup 2}, the power conversion efficiency increased from 2.4% to 2.8%, and the incident photon-to-current conversion efficiency increased from 42% to 49% corresponding to the different EEF magnitude. For an opposite direction field, the applied EEF brought a minus effect on the performance mentioned above. EEF treatment can orientate molecular ordering of the polymer, and change the morphology of the active layer. The authors suggest a explanation that the ferroelectric field has been built in the active layer, and therefore it plays a key role in PSCs system. A needle-like surface morphology of the active film was also discussed.

  16. Ring substituents mediate the morphology of PBDTTPD-PCBM bulk-heterojunction solar cells

    KAUST Repository

    Warnan, Julien

    2014-04-08

    Among π-conjugated polymer donors for efficient bulk-heterojunction (BHJ) solar cell applications, poly(benzo[1,2-b:4,5-b′]dithiophene- thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers yield some of the highest open-circuit voltages (VOC, ca. 0.9 V) and fill-factors (FF, ca. 70%) in conventional (single-cell) BHJ devices with PCBM acceptors. In PBDTTPD, side chains of varying size and branching affect polymer self-assembly, nanostructural order, and impact material performance. However, the role of the polymer side-chain pattern in the intimate mixing between polymer donors and PCBM acceptors, and on the development of the BHJ morphology is in general less understood. In this contribution, we show that ring substituents such as furan (F), thiophene (T) and selenophene (S)-incorporated into the side chains of PBDTTPD polymers-can induce significant and, of importance, very different morphological effects in BHJs with PCBM. A combination of experimental and theoretical (via density functional theory) characterizations sheds light on how varying the heteroatom of the ring substituents impacts (i) the preferred side-chain configurations and (ii) the ionization, electronic, and optical properties of the PBDTTPD polymers. In parallel, we find that the PBDT(X)TPD analogs (with X = F, T, or S) span a broad range of power conversion efficiencies (PCEs, 3-6.5%) in optimized devices with improved thin-film morphologies via the use of 1,8-diiodooctane (DIO), and discuss that persistent morphological impediments at the nanoscale can be at the origin of the spread in PCE across optimized PBDT(X)TPD-based devices. With their high VOC ∼1 V, PBDT(X)TPD polymers are promising candidates for use in the high-band gap cell of tandem solar cells. © 2014 American Chemical Society.

  17. Novel Terthiophene-Substituted Fullerene Derivatives as Easily Accessible Acceptor Molecules for Bulk-Heterojunction Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Filippo Nisic

    2014-01-01

    Full Text Available Five fulleropyrrolidines and methanofullerenes, bearing one or two terthiophene moieties, have been prepared in a convenient way and well characterized. These novel fullerene derivatives are characterized by good solubility and by better harvesting of the solar radiation with respect to traditional PCBM. In addition, they have a relatively high LUMO level and a low band gap that can be easily tuned by an adequate design of the link between the fullerene and the terthiophene. Preliminary results show that they are potential acceptors for the creation of efficient bulk-heterojunction solar cells based on donor polymers containing thiophene units.

  18. Hole and electron extraction layers based on graphene oxide derivatives for high-performance bulk heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun; Gao, Yunxiang; Yu, Dingshan; Dai, Liming [Center of Advanced Science and Engineering for Carbon, Department of Macromolecular, Science and Engineering, Case School of Engineering, Case Western Reserve University, Cleveland, Ohio (United States); Xue, Yuhua [Center of Advanced Science and Engineering for Carbon, Department of Macromolecular, Science and Engineering, Case School of Engineering, Case Western Reserve University, Cleveland, Ohio (United States); Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical College, Zhejiang 325027 (China); Durstock, Michael [Materials and Manufacturing Directorate, Air Force Research Laboratory, RXBP, Wright-Patterson Air Force Base, Ohio 45433 (United States)

    2012-05-02

    By charge neutralization of carboxylic acid groups in graphene oxide (GO) with Cs{sub 2}CO{sub 3} to afford Cesium-neutralized GO (GO-Cs), GO derivatives with appropriate modification are used as both hole- and electron-extraction layers for bulk heterojunction (BHJ) solar cells. The normal and inverted devices based on GO hole- and GO-Cs electron-extraction layers both outperform the corresponding standard BHJ solar cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Morphological Control of the Photoactive Layer in Bulk Heterojunction Organic Solar Cells

    KAUST Repository

    Su, Yisong

    2011-07-23

    For its inherent advantages, such as lightweight, low cost, flexibility, and opportunity to cover large surface areas, organic solar cells have attracted more and more attention in both academia and industry. However, the efficiency of organic solar cell is still much lower than silicon solar cells, but steadily rising as it now stands above 8%. The architecture of bulk heterojunction solar cells can improve the performance of organic solar cell a lot, but these improvements are highly dependent on the morphology of photoactive layer. Therefore, by controlling the morphology of photoactive layer, most commonly composed of a P3HT donor polymer and PCBM small molecule, the performance of organic solar cells could be optimized. The use of solvent additives in the solution formulation is particularly interesting, because it is a low cost method of controlling the phase separation of the photoactive layer and possibly removing the need for subsequent thermal and solvent vapor annealing. However, the role of the solvent additive remains not well understood and much debate remains on the mechanisms by which it impacts phase separation. In the first part of this thesis, we investigate the role of the solvent additive on the individual components (solvent, donor and acceptor) of the solution and the photoactive layer both in the bulk solution, during solution-processing and in the post-processing solid state of the film. In the second part of this thesis, we investigate the role of the additive on the blended solution state and resulting thin film phase separation. Finally, we propose a new method of controlling phase separation based on the insight into the role of the solvent additive. In the first part, we used an additive [octandiethiol (OT)] in the solvent to help the aggregation of P3HT in the solution. From the UV-vis experiments, the crystallinity of P3HT in the solutions increased while it decreased in thin films with steady increase of additive concentration. This

  20. Morphology-Dependent Trap Formation in High Performance Polymer Bulk Heterojunction Solar Cells

    KAUST Repository

    Beiley, Zach M.

    2011-06-28

    Bulk heterojunction solar cells (BHJs) based on poly[N-9″-hepta- decanyl-2,7-carbazole- alt -5,5-(4′,7′-di-2-thienyl-2′, 1′,3′-benzothiadiazole)] (PCDTBT) can have internal quantum efficiencies approaching 100% but require active layers that are too thin to absorb more than ∼70% of the above band gap light. When the active layer thickness is increased so that the cell absorbs more light, the fi ll factor and open circuit voltage decrease rapidly, so that the overall power conversion efficiency decreases. We fi nd that hole-traps in the polymer, which we characterize using space-charge limited current measurements, play an important role in the performance of PCDTBT-based BHJs and may limit the active layer thickness. Recombination due to carrier trapping is not often considered in BHJs because it is not believed to be a dominant loss mechanism in the "fruit-fl y" P3HT system. Furthermore, we show that in contrast to P3HT, PCDTBT has only weak short-range molecular order, and that annealing at temperatures above the glass transition decreases the order in the π-π stacking. The decrease in structural order is matched by the movement of hole-traps deeper into the band gap, so that thermal annealing worsens hole transport in the polymer and reduces the efficiency of PCDTBTbased BHJs. These fi ndings suggest that P3HT is not prototypical of the new class of high efficiency polymers, and that further improvement of BHJ efficiencies will necessitate the study of high efficiency polymers with low structural order. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Effect of Extended Extinction from Gold Nanopillar Arrays on the Absorbance Spectrum of a Bulk Heterojunction Organic Solar Cell

    Directory of Open Access Journals (Sweden)

    Shu-Ju Tsai

    2015-02-01

    Full Text Available We report on the effects of enhanced absorption/scattering from arrays of Au nanopillars of varied size and spacing on the spectral response of a P3HT:PCBM bulk heterojunction solar cell. Nanopillar array-patterned devices do show increased optical extinction within a narrow range of wavelengths compared to control samples without such arrays. The measured external quantum efficiency and calculated absorbance, however, both show a decrease near the corresponding wavelengths. Numerical simulations indicate that for relatively narrow nanopillars, the increased optical extinction is dominated by absorption within the nanopillars, rather than scattering, and is likely dissipated by Joule heating.

  2. Bulk Heterojunction versus Diffused Bilayer: The Role of Device Geometry in Solution p-Doped Polymer-Based Solar Cells

    OpenAIRE

    Loiudice, Anna; Rizzo, Aurora; Biasiucci, Mariano; Gigli, Giuseppe

    2012-01-01

    We exploit the effect of molecular p-type doping of P3HT in diffused bilayer (DB) polymer solar cells. In this alternative device geometry, the p-doping is accomplished in solution by blending the F4-TCNQ with P3HT. The p-doping both increases the film conductivity and reduces the potential barrier at the interface with the electrode. This results in an excellent power conversion efficiency of 4.02%, which is an improvement of ∼48% over the p-doped standard bulk heterojunction ...

  3. The Fabrication of Ordered Bulk Heterojunction Solar Cell by Nanoimprinting Lithography Method Using Patterned Silk Fibroin Mold at Room Temperature

    Science.gov (United States)

    Ding, Guangzhu; Jin, Qianqian; Chen, Qing; Hu, Zhijun; Liu, Jieping

    2015-12-01

    The performance of organic solar cell is greatly determined by the nanoscale heterojunction morphology, and finding a practical method to achieve advantageous nanostructure remains a challenge. We demonstrate here that ordered bulk heterojunction (OBHJ) solar cell can be fabricated assisted by a simple, cost-effective nanoimprinting lithography method using patterned silk fibroin film mold at room temperature. The P3HT nanogratings were achieved by nanoimprinting lithography (NIL) process, and phenyl-C61-butyric acid methyl ester (PCBM) was spin-coated on the top of P3HT nanogratings. The conducting capacity of P3HT nanograting film has little difference compared with the unimprinted film in the vertical direction, due to the same edge-on chain alignment. However, it can be found that the fabrication of OBHJ nanostructure using room temperature NIL technique with patterned silk fibroin mold is able to promote optical absorption, interfacial area, and bicontinuous pathway. Therefore, the ordered heterojunction morphology plays an important part in improving device performance due to efficient exciton diffusion, dissociation, and reducing charge recombination rate.

  4. Study Phase Separation of Donor: Acceptor in Ink jet Printed Thin Films of Bulk Heterojunction Organic Solar Cells Using AFM Phase Imaging

    International Nuclear Information System (INIS)

    In recent years, the organic solar cells have been intensively developed due to the ease and low cost fabrication process. The main component of organic solar cells is an active layer consisting of electron donor and acceptor materials. In bulk heterojunction structure, donor and acceptor are mixed and deposited as one layer [1,2]. (author)

  5. Designing ternary blend bulk heterojunction solar cells with reduced carrier recombination and a fill factor of 77%

    Science.gov (United States)

    Gasparini, Nicola; Jiao, Xuechen; Heumueller, Thomas; Baran, Derya; Matt, Gebhard J.; Fladischer, Stefanie; Spiecker, Erdmann; Ade, Harald; Brabec, Christoph J.; Ameri, Tayebeh

    2016-09-01

    In recent years the concept of ternary blend bulk heterojunction (BHJ) solar cells based on organic semiconductors has been widely used to achieve a better match to the solar irradiance spectrum, and power conversion efficiencies beyond 10% have been reported. However, the fill factor of organic solar cells is still limited by the competition between recombination and extraction of free charges. Here, we design advanced material composites leading to a high fill factor of 77% in ternary blends, thus demonstrating how the recombination thresholds can be overcome. Extending beyond the typical sensitization concept, we add a highly ordered polymer that, in addition to enhanced absorption, overcomes limits predicted by classical recombination models. An effective charge transfer from the disordered host system onto the highly ordered sensitizer effectively avoids traps of the host matrix and features an almost ideal recombination behaviour.

  6. Recent Approaches to Controlling the Nanoscale Morphology of Polymer-Based Bulk-Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Abdulra'uf Lukman Bola

    2013-11-01

    Full Text Available The need for clean, inexpensive and renewable energy has increasingly turned research attention towards polymer photovoltaic cells. However, the performance efficiency of these devices is still low in comparison with silicon-based devices. The recent introduction of new materials and processing techniques has resulted in a remarkable increase in power-conversion efficiency, with a value above 10%. Controlling the interpenetrating network morphology is a key factor in obtaining devices with improved performance. This review focuses on the influence of controlled nanoscale morphology on the overall performance of bulk-heterojunction (BHJ photovoltaic cells. Strategies such as the use of solvents, solvent annealing, polymer nanowires (NWs, and donor–acceptor (D–A blend ratios employed to control the active-layer morphologies are all discussed.

  7. Role of ITO and PEDOT:PSS in stability/degradation of polymer:fullerene bulk heterojunctions solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Girtan, M. [Laboratoire POMA, FRE CNRS 2988, Angers University, 2 Bd. Lavoisier, 49045 Angers (France); Rusu, M. [Al. I. Cuza University of Iasi, Bd. Carol I No. 11, 700506 Iasi (Romania)

    2010-03-15

    Two polymers:fullerene bulk heterojunction solar cells: [(I) poly[2-methoxy-5-(3,7-dimethyloctyloxy)]-1,4-phenylenevinylene (MDMO-PPV): methanofullerene phenyl-C{sub 61}-butyric-acid-methyl-ester ([60]PCBM) and (II) poly(3-hexylthiophene-2,5-diyl), highly regioregular (P3HT): [60]PCBM] were studied. Indium tin oxide (ITO) and/or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were/was used as transparent electrode, and lithium fluoride (LiF) was used as buffer layer for aluminium cathode. The role of ITO and PEDOT:PSS on the current-tension characteristics, on open circuit voltage V{sub oc}, and on density of short-circuit current J{sub sc} was investigated for the two polymers:PCBM blend solar cells as deposited and after 40 days ageing. (author)

  8. Performance optimization studies of solution processed bulk-heterojunction solar cells

    Science.gov (United States)

    Ali, Bakhtyar

    2011-12-01

    Organic Solar Cells (OSCs), which rely on the concept of bulk-heterojunction, stand out due primarily to their simple construction, mechanical flexibility and exceptional ease of processing. These characteristics make them potential candidates to substitute for the expensive photovoltaic counterparts. Among other OSCs, devices containing poly(3-hexylthiophene) (P3HT) and phenyl C61 butaric acid methyl ester (PCBM) as photo-active layer have shown promising results. However, the power conversion efficiency (PCE) is still lower than the required commercialization mark (˜10%). Devices with structure glass/ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al, annealed and un-annealed with device area ˜0.4 cm2 (unless otherwise stated), have been studied. An investigation of the device processing variables has led to the conclusion that the optimum loading of PCBM in the blend for optimum performance is in the range of 1:1 to 1:2. Characterization of the active layer with UV-vis absorption, PL spectra and XRD reveal that the addition of PCBM to P3HT matrix is detrimental for the self-organization of P3HT chains (crystallinity) and it also increases the resistivity. Similarly, 1,2 dichlorobenzene (DCB) has been found to be the best solvent among other solvents such as chloroform (CF) and chlorobenzene (CB), for optimum PCE. The rho(T) data from the samples (pristine P3HT and P3HT/PCBM blends) exhibit anisotropy in conduction where it follows the variable range hoping (VRH) in the lateral (parallel to film) and polaronic behavior in vertical (perpendicular to film) transport. The activation energy obtained from the fit to polaronic model is 329 meV for P3HT/ PCBM blend (1:1). Furthermore, the photovoltaic parameters extracted from a lumped circuit analysis of voltage and temperature dependence of photocurrent, JL(V), in P3HT/PCBM OSCs, completely describe the illuminated J-V data from far reverse bias to beyond the open circuit voltage (Voc). A simple model for carrier collection has been

  9. Depleted Bulk Heterojunction Colloidal Quantum Dot Photovoltaics

    KAUST Repository

    Barkhouse, D. Aaron R.

    2011-05-26

    The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows for high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar devices. A record power conversion of 5.5% under simulated AM 1.5 illumination conditions is reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Influence of the isomeric composition of the acceptor on the performance of organic bulk heterojunction P3HT:bis-PCBM solar cells

    NARCIS (Netherlands)

    Bouwer, R.K.M.; Wetzelaer, G.-J.A.H.; Blom, P.W.M.; Hummelen, J.C.

    2012-01-01

    We synthesized three isomeric subpopulations of bisadduct analogues of [6,6]-phenyl-C61-butyric acid methyl ester (bis-PCBM) via tether-directed control. Bulk heterojunction solar cells prepared using these isomers together with poly(3-hexylthiophene) (P3HT) resulted in an increase of Jsc from 72.4

  11. Performance enhancement of poly(3-hexylthiophene):methanofullerene bulk-heterojunction solar cells. : Section Title: Electrochemical, Radiational, and Thermal Energy Technology

    NARCIS (Netherlands)

    Koster, L. Jan Anton; Mihailetchi, Valentin D.; Hummelen, Jan C.; Blom, Paul W. M.

    2006-01-01

    Using a newly developed device model we have studied the effect of controlled thermal annealing on charge transport and photogeneration in bulk-heterojunction solar cells made from blend films of regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene (PCBM). With respect to the charge trans

  12. Localized photovoltaic investigations on organic semiconductors and bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Newly synthesized organic electronics materials are often available in submicrogram amounts only. Photoelectrochemical scanning droplet cell microscopy is a powerful method that allows a comprehensive characterisation of such small amounts including oxidation, reduction potentials, doping, determination of charge carriers, band gap, charge capacity, over-oxidation sensitivity and many more. Localized photoelectrochemical characterization of the poly[4,8-bis-substituted-benzo[1,2-b:4,5-b0]dithiophene-2, 6-diyl-alt-4-substituted-thieno [3,4-b] thiophene-2,6-diyl] (PBDTTT-c) and PBDTTT-c:PCBM bulk heterojunction was performed using photoelectrochemical scanning droplet cell microscopy (PE-SDCM). The optical properties and the real and imaginary part of the dielectric function, of the polymer were determined using spectroscopic ellipsometry. The photoelectrochemical characterizations were performed in a three and two electrode configuration of PE-SDCM under laser and white light illumination. The effect of illumination was characterized using dark/illumination sequences. The stability of the photocurrent was studied using longer term (600 s) illumination. Finally the effect of cell configuration and illumination conditions on the photovoltage was studied. (paper)

  13. Ambient Layer-by-Layer ZnO Assembly for Highly Efficient Polymer Bulk Heterojunction Solar Cells

    KAUST Repository

    Eita, Mohamed Samir

    2015-02-04

    The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in fl exible devices. Here, a layer-by-layer (LbL) protocol is reported as a facile, room-temperature, solution-processed method to prepare electron transport layers from commercial ZnO nanoparticles and polyacrylic acid (PAA) with a controlled and tunable porous structure, which provides large interfacial contacts with the active layer. Applying the LbL approach to bulk heterojunction polymer solar cells with an optimized ZnO layer thickness of H25 nm yields solar cell power-conversion effi ciencies (PCEs) of ≈6%, exceeding the effi ciency of amorphous ZnO interlayers formed by conventional sputtering methods. Interestingly, annealing the ZnO/PAA interlayers in nitrogen and air environments in the range of 60-300 ° C reduces the device PCEs by almost 20% to 50%, indicating the importance of conformational changes inherent to the PAA polymer in the LbL-deposited fi lms to solar cell performance. This protocol suggests a new fabrication method for solution-processed polymer solar cell devices that does not require postprocessing thermal annealing treatments and that is applicable to fl exible devices printed on plastic substrates.

  14. Structure-induced resonant tail-state regime absorption in polymer: fullerene bulk-heterojunction solar cells

    Science.gov (United States)

    Pfadler, Thomas; Kiel, Thomas; Stärk, Martin; Werra, Julia F. M.; Matyssek, Christian; Sommer, Daniel; Boneberg, Johannes; Busch, Kurt; Weickert, Jonas; Schmidt-Mende, Lukas

    2016-05-01

    In this work, we present resonant tail-state regime absorption enhanced organic photovoltaics. We combine periodically structured TiO2 bottom electrodes with P3HT-PCBM bulk-heterojunction solar cells in an inverted device configuration. The wavelength-scale patterns are transferred to the electron-selective bottom electrodes via direct laser interference patterning, a fast method compatible with roll-to-roll processing. Spectroscopic and optoelectronic device measurements suggest polarization-dependent absorption enhancement along with photocurrent generation unambiguously originating from the population of tail states. We discuss the effects underlying these absorption patterns with the help of electromagnetic simulations using the discontinuous Galerkin time domain method. For this, we focus on the total absorption spectra along with spatially resolved power loss densities. Our simulations stress the tunability of the absorption resonances towards arbitrary wavelength regions.

  15. Selective observation of photo-induced electric fields inside different material components in bulk-heterojunction organic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiangyu; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa, E-mail: iwamoto@pe.titech.ac.jp [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1, S3-33 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2014-01-06

    By using electric-field-induced optical second-harmonic generation (EFISHG) measurement at two laser wavelengths of 1000 nm and 860 nm, we investigated carrier behavior inside the pentacene and C{sub 60} component of co-deposited pentacene:C{sub 60} bulk-heterojunctions (BHJs) organic solar cells (OSCs). The EFISHG experiments verified the presence of two carrier paths for electrons and holes in BHJs OSCs. That is, two kinds of electric fields pointing in opposite directions are identified as a result of the selectively probing of SHG activation from C{sub 60} and pentacene. Also, under open-circuit conditions, the transient process of the establishment of open-circuit voltage inside the co-deposited layer has been directly probed, in terms of photovoltaic effect. The EFISHG provides an additional promising method to study carrier path of electrons and holes as well as dissociation of excitons in BHJ OSCs.

  16. Influence of optical interference and carrier lifetime on the short circuit current density of organic bulk heterojunction solar cells

    Institute of Scientific and Technical Information of China (English)

    You Hai-Long; Zhang Chun-Fu

    2009-01-01

    Based on simple analytical equations, short circuit current density (Jsc) of the organic bulk heterojunction solar cells has been calculated. It is found that the optical interference effect plays a very important role in the determination of JSC;and obvious oscillatory behaviour of Jsc was observed as a function of thickness. At the same time, the influence of JSC only increases the carrier lifetime on JSC also cannot be neglected. When the carrier lifetime is relatively short, at the initial stage and then decreases rapidly with the increase of active layer thickness. However, for a relatively long carrier lifetime, the exciton dissociation probability must be considered, and Jsc behaves wave-like with the increase of active layer thickness. The validity of this model is confirmed by the experimental results.

  17. Nanofiber-based bulk-heterojunction organic solar cells using coaxial electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Bedford, Nicholas M. [Nanoelectronics Laboratory, Department of Electrical and Computer Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States); Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH, 45221 (United States); Dickerson, Matthew B.; Drummy, Lawrence F.; Koerner, Hilmar; Singh, Kristi M.; Vasudev, Milana C.; Durstock, Michael F.; Naik, Rajesh R. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, OH, 45433 (United States); Steckl, Andrew J. [Nanoelectronics Laboratory, Department of Electrical and Computer Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States)

    2012-09-15

    Nanofibers consisting of the bulk heterojunction organic photovoltaic (BHJ-OPV) electron donor-electron acceptor pair poly(3-hexylthiophene):phenyl-C{sub 61}-butyric acid methyl ester (P3HT:PCBM) are produced through a coaxial electrospinning process. While P3HT:PCBM blends are not directly electrospinnable, P3HT:PCBM-containing fibers are produced in a coaxial fashion by utilizing polycaprolactone (PCL) as an electrospinnable sheath material. Pure P3HT:PCBM fibers are easily obtained after electrospinning by selectively removing the PCL sheath with cyclopentanone (average diameter 120 {+-} 30 nm). These fibers are then incorporated into the active layer of a BHJ-OPV device, which results in improved short-circuit current densities, fill factors, and power-conversion efficiencies (PCE) as compared to thin-film devices of identical chemical composition. The best-performing fiber-based devices exhibit a PCE of 4.0%, while the best thin-film devices have a PCE of 3.2%. This increase in device performance is attributed to the increased in-plane alignment of P3HT polymer chains on the nanoscale, caused by the electrospun fibers, which leads to increased optical absorption and subsequent exciton generation. This methodology for improving device performance of BHJ-OPVs could also be implemented for other electron donor-electron acceptor systems, as nanofiber formation is largely independent of the PV material. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. The importance of fullerene percolation in the mixed regions of polymer-fullerene bulk heterojunction solar cells

    KAUST Repository

    Bartelt, Jonathan A.

    2012-10-26

    Most optimized donor-acceptor (D-A) polymer bulk heterojunction (BHJ) solar cells have active layers too thin to absorb greater than - 80% of incident photons with energies above the polymer\\'s band gap. If the thickness of these devices could be increased without sacrifi cing internal quantum effi ciency, the device power conversion effi ciency (PCE) could be signifi cantly enhanced. We examine the device characteristics of BHJ solar cells based on poly(di(2- ethylhexyloxy)benzo[1,2- b :4,5- b \\' ]dithiophene- co -octylthieno[3,4- c ]pyrrole-4,6- dione) (PBDTTPD) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) with 7.3% PCE and fi nd that bimolecular recombination limits the active layer thickness of these devices. Thermal annealing does not mitigate these bimolecular recombination losses and drastically decreases the PCE of PBDTTPD BHJ solar cells. We characterize the morphology of these BHJs before and after thermal annealing and determine that thermal annealing drastically reduces the concentration of PCBM in the mixed regions, which consist of PCBM dispersed in the amorphous portions of PBDTTPD. Decreasing the concentration of PCBM may reduce the number of percolating electron transport pathways within these mixed regions and create morphological electron traps that enhance charge-carrier recombination and limit device quantum effi ciency. These fi ndings suggest that (i) the concentration of PCBM in the mixed regions of polymer BHJs must be above the PCBM percolation threshold in order to attain high solar cell internal quantum effi ciency, and (ii) novel processing techniques, which improve polymer hole mobility while maintaining PCBM percolation within the mixed regions, should be developed in order to limit bimolecular recombination losses in optically thick devices and maximize the PCE of polymer BHJ solar cells. © 2013 WILEY-VCH Verlag GmbH and Co. © 2013 WILEY-VCH Verlag GmbH & Co.

  19. Efficient polymer:fullerene bulk heterojunction solar cells with n-type doped titanium oxide as an electron transport layer

    International Nuclear Information System (INIS)

    We have reported a highly n-type doped solution-processed titanium metal oxide (TiOx) for use as an efficient electron-transport layer (ETL) in polymer:fullerene bulk heterojunction (BHJ) solar cells. When the metal ions (Ti) in TiOx are partially substituted by niobium (Nb), the charge carrier density increased, by an order of magnitude, because of the large electronegativity of Nb compared to that of Ti. Therefore, the work function (WF) of Nb-doped metal oxide (Nb-TiOx) decreases from 4.75 eV (TiOx) to 4.66 eV (Nb-TiOx), leading to an enhancement in the power conversion efficiency (PCE) of BHJ solar cells with a Nb-TiOx ETL (from 7.99% to 8.40%). - Highlights: • Solution processable Nb-doped TiOx was developed by simple sol-gel synthesis. • Charge carrier density in TiOx is significantly increased by introducing Nb element. • The work function value of Nb-doped TiOx is reduced by introducing Nb element. • A charge recombination inside of PSC with Nb-TiOx was effectively suppressed

  20. Efficient polymer:fullerene bulk heterojunction solar cells with n-type doped titanium oxide as an electron transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Youna [Heeger Center for Advanced Material & Research Institute of Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Geunjin [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Heejoo, E-mail: heejook@gist.ac.kr [Heeger Center for Advanced Material & Research Institute of Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kim, Sun Hee [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Lee, Kwanghee, E-mail: klee@gist.ac.kr [Heeger Center for Advanced Material & Research Institute of Solar and Sustainable Energies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2015-05-29

    We have reported a highly n-type doped solution-processed titanium metal oxide (TiO{sub x}) for use as an efficient electron-transport layer (ETL) in polymer:fullerene bulk heterojunction (BHJ) solar cells. When the metal ions (Ti) in TiO{sub x} are partially substituted by niobium (Nb), the charge carrier density increased, by an order of magnitude, because of the large electronegativity of Nb compared to that of Ti. Therefore, the work function (WF) of Nb-doped metal oxide (Nb-TiO{sub x}) decreases from 4.75 eV (TiO{sub x}) to 4.66 eV (Nb-TiO{sub x}), leading to an enhancement in the power conversion efficiency (PCE) of BHJ solar cells with a Nb-TiO{sub x} ETL (from 7.99% to 8.40%). - Highlights: • Solution processable Nb-doped TiO{sub x} was developed by simple sol-gel synthesis. • Charge carrier density in TiO{sub x} is significantly increased by introducing Nb element. • The work function value of Nb-doped TiO{sub x} is reduced by introducing Nb element. • A charge recombination inside of PSC with Nb-TiO{sub x} was effectively suppressed.

  1. Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

    Institute of Scientific and Technical Information of China (English)

    朱键卓; 祁令辉; 杜会静; 柴莺春

    2015-01-01

    We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons (holes) in the device are collected by anode (cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination (BR) or geminate recombination (GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same. Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.

  2. Interplay Between Side Chain Pattern, Polymer Aggregation, and Charge Carrier Dynamics in PBDTTPD:PCBM Bulk-Heterojunction Solar Cells

    KAUST Repository

    Dyer-Smith, Clare

    2015-05-01

    Poly(benzo[1,2-b:4,5-b′]dithiophene–alt–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymer donors with linear side-chains yield bulk-heterojunction (BHJ) solar cell power conversion efficiencies (PCEs) of about 4% with phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor, while a PBDTTPD polymer with a combination of branched and linear substituents yields a doubling of the PCE to 8%. Using transient optical spectroscopy it is shown that while the exciton dissociation and ultrafast charge generation steps are not strongly affected by the side chain modifications, the polymer with branched side chains exhibits a decreased rate of nongeminate recombination and a lower fraction of sub-nanosecond geminate recombination. In turn the yield of long-lived charge carriers increases, resulting in a 33% increase in short circuit current (J sc). In parallel, the two polymers show distinct grazing incidence X-ray scattering spectra indicative of the presence of stacks with different orientation patterns in optimized thin-film BHJ devices. Independent of the packing pattern the spectroscopic data also reveals the existence of polymer aggregates in the pristine polymer films as well as in both blends which trap excitons and hinder their dissociation.

  3. Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

    Institute of Scientific and Technical Information of China (English)

    Mehdi Ahmadi; Sajjad Rashidi Dafeh

    2015-01-01

    In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV–visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly (3-hexylthiophene):[6-6] Phenyl-(6) butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17%with a high FF beyond 60%was achieved.

  4. The effect of annealing treatment on the performance of bulk heterojunction solar cells with donor and acceptor different weight ratios

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Bulk heterojunction organic solar cells(OSCs) based on the blend of poly(2-methoxy-5(2’-ethyl-hexyloxy)-1,4-phenylenevinylene(MEH-PPV) and [6,6]-phenyl C61 butyric acid methyl ester(PCBM) with different weight ratios(from 1:3 to 1:5) have been fabricated and the effect of annealing treatment on the performance of OSCs has also been studied.Experimental results point to the best optimized doping concentration 1:4 for MEH-PPV:PCBM.Furthermore,it is found that the devices with annealing treatment at 150℃ with 8 min show better performance compared with the devices without treatment.The series resistance(Rs) is decreased,while the shunt resistance(Rsh) increased by nearly 1.5 times.The short-circuit current density(Jsc) and fill factor(FF) are improved by annealing treatment.As a result,the power conversion efficiency(PCE) of the devices increases from 0.49 % to 1.21 % with the ratio of 1:3 and from 1.09% to 1.42% with the ratio of 1:4.

  5. Bulk-heterojunction polymer solar cells with polyaniline-silica nanocomposites as an efficient hole-collecting layer

    Science.gov (United States)

    Mohsennia, Mohsen; Bidgoli, Maryam Massah; Khoddami, Mohammad Hossein; Salehi, Alireza; Boroumand, Farhad Akbari

    2016-01-01

    At first, bulk-heterojunction polymer solar cells (PSCs) with conventional configuration: ITO/PEDOT:PSS/P3HT:C60/Al, containing different blend ratios of poly(3-hexylthiophene):fullerene, (P3HT):C60 as active layer have been fabricated. The effect of replacement of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by the prepared polyaniline-fumed silica (PANI-SiO2) nanocomposites as the hole-collecting layer (HCL) on the performance of the fabricated PSC with the optimized blending ratio of P3HT:C60 was examined in detail. According to the obtained results, it was found that the fabricated PSC with PANI-SiO2 nanocomposite containing 10% SiO2 (PANI-10% SiO2) as the HCL and P3HT:C60 with the optimized blending ratio (P3HT:33% C60) as active layer exhibited best performance with a fill factor (FF) of 0.35, compared to the PSC containing conventional PEDOT:PSS HCL with an FF of 0.32. Our demonstration suggests that PANI-SiO2 nanocomposites could be promising HCL replacing PEDOT:PSS in PSCs as well as other organic electronic devices.

  6. The effect of annealing treatment on the performance of bulk heterojunction solar cells with donor and acceptor different weight ratios

    Institute of Scientific and Technical Information of China (English)

    SONG JingLu; XU Zheng; ZHANG FuJun; ZHAO SuLing; HU Tao; LI JunMing; LIU XiaoDong; YUE Xin; WANG YongSheng

    2009-01-01

    Bulk heterojunction organic solar cells (OSCs) based on the blend of poly(2-methoxy-5(2'-ethyl-hexyloxy)-1,4-phenylenevinyiene (MEH-PPV) and[6,6]-phenyl C61 butyric acid methyl ester (PCBM) with different weight ratios (from 1:3 to 1:5) have been fabricated and the effect of annealing treatment on the performance of OSCs has also been studied.Experimental results point to the best optimized doping concentration 1:4 for MEH-PPV:PCBM.Furthermore,it is found that the devices with annealing treatment at 150℃ with 8 min show better performance compared with the devices without treatment.The series resistance (Rs) is decreased,while the shunt resistance (Rsh) increased by nearly 1.5 times.The short-circuit current density (Jsc) and fill factor (FF) are improved by annealing treatment.As a result,the power conversion efficiency (PCE) of the devices increases from 0.49 % to 1.21 % with the ratio of 1:3 and from 1.09% to 1.42% with the ratio of 1:4.

  7. The influence of microstructure on charge separation dynamics in organic bulk heterojunction materials for solar cell applications

    KAUST Repository

    Scarongella, Mariateresa

    2014-01-01

    Light-induced charge formation is essential for the generation of photocurrent in organic solar cells. In order to gain a better understanding of this complex process, we have investigated the femtosecond dynamics of charge separation upon selective excitation of either the fullerene or the polymer in different bulk heterojunction blends with well-characterized microstructure. Blends of the pBTTT and PBDTTPD polymers with PCBM gave us access to three different scenarios: either a single intermixed phase, an intermixed phase with additional pure PCBM clusters, or a three-phase microstructure of pure polymer aggregates, pure fullerene clusters and intermixed regions. We found that ultrafast charge separation (by electron or hole transfer) occurs predominantly in intermixed regions, while charges are generated more slowly from excitons in pure domains that require diffusion to a charge generation site. The pure domains are helpful to prevent geminate charge recombination, but they must be sufficiently small not to become exciton traps. By varying the polymer packing, backbone planarity and chain length, we have shown that exciton diffusion out of small polymer aggregates in the highly efficient PBDTTPD:PCBM blend occurs within the same chain and is helped by delocalization. This journal is © the Partner Organisations 2014.

  8. Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

    Science.gov (United States)

    Mehdi, Ahmadi; Sajjad Rashidi, Dafeh

    2015-11-01

    In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV-visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly (3-hexylthiophene):[6-6] Phenyl-(6) butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

  9. Efficient inverted bulk-heterojunction solar cells from low-temperature processing of amorphous ZnO buffer layers

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2014-01-01

    In this report, we demonstrate that solution-processed amorphous zinc oxide (a-ZnO) interlayers prepared at low temperatures (∼100 °C) can yield inverted bulk-heterojunction (BHJ) solar cells that are as efficient as nanoparticle-based ZnO requiring comparably more complex synthesis or polycrystalline ZnO films prepared at substantially higher temperatures (150-400 °C). Low-temperature, facile solution-processing approaches are required in the fabrication of BHJ solar cells on flexible plastic substrates, such as PET. Here, we achieve efficient inverted solar cells with a-ZnO buffer layers by carefully examining the correlations between the thin film morphology and the figures of merit of optimized BHJ devices with various polymer donors and PCBM as the fullerene acceptor. We find that the most effective a-ZnO morphology consists of a compact, thin layer with continuous substrate coverage. In parallel, we emphasize the detrimental effect of forming rippled surface morphologies of a-ZnO, an observation which contrasts with results obtained in polycrystalline ZnO thin films, where rippled morphologies have been reported to improve efficiency. After optimizing the a-ZnO morphology at low processing temperature for inverted P3HT:PCBM devices, achieving a power conversion efficiency (PCE) of ca. 4.1%, we demonstrate inverted solar cells with low bandgap polymer donors on glass/flexible PET substrates: PTB7:PC71BM (PCE: 6.5% (glass)/5.6% (PET)) and PBDTTPD:PC71BM (PCE: 6.7% (glass)/5.9% (PET)). Finally, we show that a-ZnO based inverted P3HT:PCBM BHJ solar cells maintain ca. 90-95% of their initial PCE even after a full year without encapsulation in a nitrogen dry box, thus demonstrating excellent shelf stability. The insight we have gained into the importance of surface morphology in amorphous zinc oxide buffer layers should help in the development of other low-temperature solution-processed metal oxide interlayers for efficient flexible solar cells. This journal is

  10. Enhanced performance of polymer:fullerene bulk heterojunction solar cells upon graphene addition

    Energy Technology Data Exchange (ETDEWEB)

    Robaeys, Pieter, E-mail: pieter.robaeys@uhasselt.be; Dierckx, Wouter; Dexters, Wim; Spoltore, Donato; Drijkoningen, Jeroen [Institute for Materials Research (IMO), Hasselt University (Belgium); Bonaccorso, Francesco [Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge (United Kingdom); Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, 16163 Genova (Italy); Bourgeois, Emilie; D' Haen, Jan; Haenen, Ken; Manca, Jean V.; Nesladek, Milos [Institute for Materials Research (IMO), Hasselt University (Belgium); IMOMEC, IMEC vzw (Belgium); Liesenborgs, Jori; Van Reeth, Frank [Expertise centre for Digital Media (EDM), Hasselt University (Belgium); Lombardo, Antonio; Ferrari, Andrea C. [Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge (United Kingdom)

    2014-08-25

    Graphene has potential for applications in solar cells. We show that the short circuit current density of P3HT (Poly(3-hexylthiophene-2,5-diyl):PCBM((6,6)-Phenyl C61 butyric acid methyl ester) solar cells is enhanced by 10% upon the addition of graphene, with a 15% increase in the photon to electric conversion efficiency. We discuss the performance enhancement by studying the crystallization of P3HT, as well as the electrical transport properties. We show that graphene improves the balance between electron and hole mobilities with respect to a standard P3HT:PCBM solar cell.

  11. On the Efficiency Limit of Conjugated Polymer:Fullerene-Based Bulk Heterojunction Solar Cells.

    Science.gov (United States)

    Scharber, Markus C

    2016-03-01

    The power conversion efficiency potential of eight high-performance polymer-fullerene blends is investigated. All studied absorbers show the typical organic solar cell losses limiting their performance to ≈13%. PMID:26757236

  12. Structural Factors That Affect the Performance of Organic Bulk Heterojunction Solar Cells

    KAUST Repository

    Vandewal, Koen

    2013-08-27

    The performance of polymer:fullerene solar cells is strongly affected by the active layer morphology and polymer microstructure. In this Perspective, we review ongoing research on how structural factors influence the photogeneration and collection of charge carriers as well as charge carrier recombination and the related open-circuit voltage. We aim to highlight unexplored research opportunities and provide some guidelines for the synthesis of new conjugated polymers for high-efficiency solar cells. © 2013 American Chemical Society.

  13. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  14. Material structure-composite morphology-photovoltaic performance relationship for organic bulk heterojunction solar cells.

    Science.gov (United States)

    Troshin, Pavel A; Mukhacheva, Olga A; Goryachev, Andrey E; Dremova, Nadezhda N; Voylov, Dmitry; Ulbricht, Christoph; Egbe, Daniel A M; Sariciftci, Niyazi Serdar; Razumov, Vladimir F

    2012-10-01

    Conjugated PPV-PPE copolymer has been investigated in organic solar cells in combination with twelve different fullerene derivatives. It was shown that the length of solubilizing alkyl chains in the fullerene derivative structures correlates well with the performance of photovoltaic cells.

  15. Simple, highly efficient vacuum-processed bulk heterojunction solar cells based on merocyanine dyes

    Energy Technology Data Exchange (ETDEWEB)

    Steinmann, Vera; Kronenberg, Nils M.; Lenze, Martin R.; Graf, Steven M.; Hertel, Dirk; Meerholz, Klaus [Department fuer Chemie, Universitaet Koeln, Luxemburger Strasse 116, 50939 Koeln (Germany); Buerckstuemmer, Hannah; Tulyakova, Elena V.; Wuerthner, Frank [Institut fuer Organische Chemie and Roentgen Research Center for Complex Material Systems, Universitaet Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany)

    2011-10-15

    In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum-processed small molecule solar cell based on merocyanine dyes - traditional colorants that can easily be mass-produced and purified - is presented. In the past, merocyanines have been successfully introduced in solution-processed as well as vacuum-processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Structure–property relationships of oligothiophene–isoindigo polymers for efficient bulk-heterojunction solar cells

    DEFF Research Database (Denmark)

    Ma, Zaifei; Sun, Wenjun; Himmelberger, Scott;

    2014-01-01

    ) in the repeating unit alters both polymer crystallinity and polymer–fullerene interfacial energetics, which results in a decreasing open-circuit voltage (Voc) of the solar cells with increasing n. The short-circuit current density (Jsc) of P1TI:PCBM devices is limited by the absence of a significant driving force...... for electron transfer. Instead, blends based on P5TI and P6TI feature large polymer domains, which limit charge generation and thus Jsc. The best PV performance with a power conversion efficiency of up to 6.9% was achieved with devices based on P3TI, where a combination of a favorable morphology and an optimal...... for the fabrication of efficient solar cells that combine a minimal loss in Voc with a high Jsc....

  17. A mechanistic understanding of processing additive-induced efficiency enhancement in bulk heterojunction organic solar cells

    KAUST Repository

    Schmidt, Kristin

    2013-10-31

    The addition of processing additives is a widely used approach to increase power conversion efficiencies for many organic solar cells. We present how additives change the polymer conformation in the casting solution leading to a more intermixed phase-segregated network structure of the active layer which in turn results in a 5-fold enhancement in efficiency. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Evaluating effect of surface state density at the interfaces in degraded bulk heterojunction organic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Swati, E-mail: drswatia@yahoo.com [Department of Physics, Zakir Husain College, University of Delhi, Delhi 110002 (India); Singh, Vinamrita [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Arora, Manoj [Department of Physics, Ramjas College, University of Delhi, Delhi 110007 (India); Pal Tandon, Ram [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2012-08-01

    Degradation and short shelf life have been observed experimentally in poly(3-hexylthiophene) (P3HT): 6,6-phenyl C61-butyric acid methyl ester (PCBM) based blend solar cells. Both dark and illuminated current-voltage characteristics could be explained quantitatively with a proposed single model for a typical degraded organic solar cell-glass/ITO/PEDOT:PSS/P3HT:PCBM/Al. It has been found that surface state density, interface thickness, tunneling coefficient and occupation probabilities of the interface states becomes important with the passage of time. To look into the problem the activity at ITO/PEDOT:PSS and P3HT:PCBM/Al interfaces are studied using realistic values of the interfaces. The experimental J-V characteristics is well explained with the inclusion of tunneling current through these surface states and becomes the dominant current component for the degraded cell. It is also found that surface state density increases to 10{sup 12}-10{sup 13} cm{sup -2} eV{sup -1}, which has been verified with C-V measurements and also is in agreement with our proposed model for BHJ solar cell after 150 h of fabrication.

  19. CONTROLLING THE 3D NANOSCALE ORGANIZATION OF BULK HETEROJUNCTION POLYMER SOLAR CELLS

    Institute of Scientific and Technical Information of China (English)

    Svetlana S. Van Bavel; Erwan Sourty; Gijsbertus de With; Joachim Loos

    2009-01-01

    In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene)(P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology accounts for the considerable increase of the power conversion efficiency in corresponding solar cell devices.

  20. Effect of ZnCdTe-Alloyed Nanocrystals on Polymer–Fullerene Bulk Heterojunction Solar Cells

    OpenAIRE

    Wang Yan; Hou Yanbing; Tang Aiwei; Feng Zhihui; Feng Bin; Li Yan; Teng Feng

    2009-01-01

    Abstract The photovoltaic properties of solar cell based on the blends of poly[2-methoxy-5-(2-ethylhexoxy-1,4-phenylenevinylene) (MEH-PPV), fullerene (C60), and ZnCdTe-alloyed nanocrystals were investigated. Comparing the spectral response of photocurrent of the MEH-PPV:C60(+ZnCdTe) nanocomposite device with that of the devices based on MEH-PPV:C60and pristine MEH-PPV, one can find that the nanocomposite device exhibits an enhanced photocurrent. In comparing the composite devices with differe...

  1. Effect of TiO2 Nanotubes on Polymer-Fullerene Bulk Heterojunction Solar Cells

    Institute of Scientific and Technical Information of China (English)

    LI Yan; HOU Yan-Bing; JIN Hui; SHI Quan-Min; ZHANG Xiu-Long

    2007-01-01

    We investigate the photovoltaic properties of hybrid organic solar cell based on the blend of poly[2-methoxy-5-(2_-ethylhexoxy-1,4-phenylenevinylene) (MEH-PPV), C60 and titanium dioxide (TiO2) nanotubes. In comparison of the composite devices with different TiO2:[MEH-PPV +C60] weight ratios of 1wt.% (D1-1), 2wt.% (D1-2),3wt.% (D1-3), 5wt.% (D1-4), 10wt.% (D1-5) and 20wt.% (D1-6), it is found that the device D1-3 exhibits the best performance. The conversion efficiency is improved by a factor of 3 compared with the MEH-PPV:C60 device.

  2. Analysis of Triplet Exciton Loss Pathways in PTB7:PC71BM Bulk Heterojunction Solar Cells

    Science.gov (United States)

    Kraus, Hannes; Heiber, Michael C.; Väth, Stefan; Kern, Julia; Deibel, Carsten; Sperlich, Andreas; Dyakonov, Vladimir

    2016-07-01

    A strategy for increasing the conversion efficiency of organic photovoltaics has been to increase the VOC by tuning the energy levels of donor and acceptor components. However, this opens up a new loss pathway from an interfacial charge transfer state to a triplet exciton (TE) state called electron back transfer (EBT), which is detrimental to device performance. To test this hypothesis, we study triplet formation in the high performing PTB7:PC71BM blend system and determine the impact of the morphology-optimizing additive 1,8-diiodoctane (DIO). Using photoluminescence and spin-sensitive optically detected magnetic resonance (ODMR) measurements at low temperature, we find that TEs form on PC71BM via intersystem crossing from singlet excitons and on PTB7 via EBT mechanism. For DIO blends with smaller fullerene domains, an increased density of PTB7 TEs is observed. The EBT process is found to be significant only at very low temperature. At 300 K, no triplets are detected via ODMR, and electrically detected magnetic resonance on optimized solar cells indicates that TEs are only present on the fullerenes. We conclude that in PTB7:PC71BM devices, TE formation via EBT is impacted by fullerene domain size at low temperature, but at room temperature, EBT does not represent a dominant loss pathway.

  3. Analysis of Triplet Exciton Loss Pathways in PTB7:PC71BM Bulk Heterojunction Solar Cells

    Science.gov (United States)

    Kraus, Hannes; Heiber, Michael C.; Väth, Stefan; Kern, Julia; Deibel, Carsten; Sperlich, Andreas; Dyakonov, Vladimir

    2016-01-01

    A strategy for increasing the conversion efficiency of organic photovoltaics has been to increase the VOC by tuning the energy levels of donor and acceptor components. However, this opens up a new loss pathway from an interfacial charge transfer state to a triplet exciton (TE) state called electron back transfer (EBT), which is detrimental to device performance. To test this hypothesis, we study triplet formation in the high performing PTB7:PC71BM blend system and determine the impact of the morphology-optimizing additive 1,8-diiodoctane (DIO). Using photoluminescence and spin-sensitive optically detected magnetic resonance (ODMR) measurements at low temperature, we find that TEs form on PC71BM via intersystem crossing from singlet excitons and on PTB7 via EBT mechanism. For DIO blends with smaller fullerene domains, an increased density of PTB7 TEs is observed. The EBT process is found to be significant only at very low temperature. At 300 K, no triplets are detected via ODMR, and electrically detected magnetic resonance on optimized solar cells indicates that TEs are only present on the fullerenes. We conclude that in PTB7:PC71BM devices, TE formation via EBT is impacted by fullerene domain size at low temperature, but at room temperature, EBT does not represent a dominant loss pathway. PMID:27380928

  4. Controlling solution-phase polymer aggregation with molecular weight and solvent additives to optimize polymer-fullerene bulk heterojunction solar cells

    KAUST Repository

    Bartelt, Jonathan A.

    2014-03-20

    The bulk heterojunction (BHJ) solar cell performance of many polymers depends on the polymer molecular weight (M n) and the solvent additive(s) used for solution processing. However, the mechanism that causes these dependencies is not well understood. This work determines how M n and solvent additives affect the performance of BHJ solar cells made with the polymer poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b\\']dithiophene-co- octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD). Low M n PBDTTPD devices have exceedingly large fullerene-rich domains, which cause extensive charge-carrier recombination. Increasing the M n of PBDTTPD decreases the size of these domains and significantly improves device performance. PBDTTPD aggregation in solution affects the size of the fullerene-rich domains and this effect is linked to the dependency of PBDTTPD solubility on M n. Due to its poor solubility high M n PBDTTPD quickly forms a fibrillar polymer network during spin-casting and this network acts as a template that prevents large-scale phase separation. Furthermore, processing low M n PBDTTPD devices with a solvent additive improves device performance by inducing polymer aggregation in solution and preventing large fullerene-rich domains from forming. These findings highlight that polymer aggregation in solution plays a significant role in determining the morphology and performance of BHJ solar cells. The performance of poly(di(2-ethylhexyloxy) benzo[1,2-b:4,5-b\\']dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) bulk heterojunction solar cells strongly depends on the polymer molecular weight, and processing these bulk heterojunctions with a solvent additive preferentially improves the performance of low molecular weight devices. It is demonstrated that polymer aggregation in solution significantly impacts the thin-film bulk heterojunction morphology and is vital for high device performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Synthesis and characterization of quinoxaline-based polymers for bulk-heterojunction polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bathula, Chinna [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of); Song, Chang Eun [Department of Materials Science and Engineering, Korea Advanced Instituted of Science and Technology, Daejeon 305–701 (Korea, Republic of); Lee, Woo-Hyung [Department of Chemistry, The Catholic University of Korea, Bucheon, Gyeonggi-do 420–743 (Korea, Republic of); Lee, Jaemin; Badgujar, Sachin; Koti, Rajesh [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of); Kang, In-Nam [Department of Chemistry, The Catholic University of Korea, Bucheon, Gyeonggi-do 420–743 (Korea, Republic of); Shin, Won Suk [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of); Ahn, Taek, E-mail: taekahn@ks.ac.kr [Department of Chemistry, Kyungsung University, Busan 608–736 (Korea, Republic of); Lee, Jong-Cheol [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of); Moon, Sang-Jin, E-mail: moonsj@krict.re.kr [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of); Lee, Sang Kyu, E-mail: skyulee@krict.re.kr [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305–600 (Korea, Republic of)

    2013-06-30

    A series of quinoxaline (Qx)-based copolymers, poly[2,7-(9,9-bis(2-ethylhexyl)dibenzosilole)-alt-5,5-(5′, 8′-di-2-thienyl-2,3-bis(4-octyloxyl)phenyl)quinoxaline] (P1), poly[4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-alt-5,5-(5′, 8′-di-2-thienyl-2,3-bis(4-octyloxyl)phenyl)quinoxaline] (P2), and poly[4,4′-bis(2-ethylhexyl)-dithieno[3,2-b:2′,3′-d]silole-alt-5,5-(5′, 8′-di-2-thienyl-2,3-bis(4-octyloxyl)phenyl)quinoxaline] (P3), were synthesized and characterized for use in polymer solar cells (PSCs). We describe the effects of the various donor segments on the optical, electrochemical, field-effect carrier mobilities, and photovoltaic characteristics of the resulting Qx-based copolymers. The results indicated that the donor units in the copolymers significantly influenced the band gap, electronic energy levels, carrier mobilities, and photovoltaic properties of the copolymers. The band gaps of the copolymers were 1.71–2.03 eV. Under optimized conditions, the Qx-based polymers showed power conversion efficiencies for the PSCs of 0.87–2.15% under AM 1.5 illumination (100 mW/cm{sup 2}). Among the studied Qx-based copolymers, P2, which contained a benzo[1,2-b:4,5-b′]dithiophene unit, showed a power conversion efficiency of 2.15% with a short circuit current of 7.06 mA/cm{sup 2}, an open-circuit voltage of 0.67 V, and a fill factor of 0.46, under AM 1.5 illumination (100 mW/cm{sup 2}). - Highlights: • A series of quinoxaline (Qx)-based copolymers were synthesized. • We described the effects of the donor segments on photovoltaic characteristics. • The Qx-based polymers showed power conversion efficiencys in the range 0.87–2.15%.

  6. Effect of ligand exchange of Cu2ZnSnS4 nanocrystals on the charge transport and photovoltaic performance of nanostructured depleted bulk heterojunction solar cell

    International Nuclear Information System (INIS)

    Cu2ZnSnS4 (CZTS) nanocrystals combining the advantage of feasible solution-phase synthesis and processing are perceived as promising materials for application in efficient, low-cost photovoltaic technology. Herein, we have got surfactant-free CZTS nanocrystals by a novel ligand exchange method, and the obtained CZTS nanocrystals were deposited onto ZnO nanorod arrays to construct depleted bulk heterojunction solar cell. The all-inorganic CZTS nanocrystal solar cells demonstrated a remarkable improvement in Jsc (from 8.14 to 13.97 mA/cm2) and power conversion efficiency (from 1.83 to 3.34 %) compared with surfactant-capped CZTS nanocrystals. Using surface photovoltage spectrum, the influence of ligand exchange of CZTS nanocrystals on the charge transport and photovoltaic performance of the nanostructured CZTS solar cells was discussed

  7. Schottky diodes between Bi2S3 nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

    International Nuclear Information System (INIS)

    We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi2S3 nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi2S3 nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells

  8. Schottky diodes between Bi2S3 nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

    Science.gov (United States)

    Saha, Sudip K.; Pal, Amlan J.

    2015-07-01

    We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi2S3 nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi2S3 nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells.

  9. Schottky diodes between Bi{sub 2}S{sub 3} nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Sudip K.; Pal, Amlan J., E-mail: sspajp@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2015-07-07

    We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi{sub 2}S{sub 3} nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi{sub 2}S{sub 3} nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells.

  10. Simulation study of the losses and influences of geminate and bimolecular recombination on the performances of bulk heterojunction organic solar cells

    Science.gov (United States)

    Zhu, Jian-Zhuo; Qi, Ling-Hui; Du, Hui-Jing; Chai, Ying-Chun

    2015-10-01

    We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons (holes) in the device are collected by anode (cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination (BR) or geminate recombination (GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same. Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells. Project supported by the Natural Science Foundation of Hebei Province, China (Grant No. A2012203016), the Science Fund from the Education Department of Hebei Province, China (Grant Nos. QN20131103 and Z2009114), the Doctor Foundation of Yanshan University, China (Grant No. B580), and the Young Teachers' Research Project of Yanshan University, China (Grant No. 13LGB028).

  11. Thickness and concentration effect of P3HT in P3HT:graphene nanocomposites based bulk-heterojunction organic solar cells

    Science.gov (United States)

    Shariff, Nur Shakina Mohd; Saad, Puteri Sarah Mohamad; Affendi, Irma Hidayanti Halim; Mahmood, Mohamad Rusop; Shariffudin, Shafinaz Sobihana

    2016-07-01

    There has been an increasing interest towards organic solar cells after the discovery of conjugated polymer and bulk-heterojunction concept. Eventhough organic solar cells are less expensive than inorganic solar cells but the power conversion energy is still considered low. The main objective of this research is to investigate the effect of the P3HT's thickness and concentration towards the efficiency of the P3HT:Graphene solar cells. A simulation software that is specialize for photovoltaic called SCAPS is used in this research to simulate the effect on the solar cells. The solar cell's structure will be drawn inside the simulation and the parameters for each layers is inserted. The result such as the open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and efficiency (η) will be calculated by the software and all the results will be put into one graph. P3HT's thickness of 100 nm and concentration of 1×1016 cm-3 has the best overall results with an open circuit voltage (Voc) of 4.55 V, short circuit current density (Jsc) of 16.76 mA/cm2, fill factor (FF) of 19.70 % and efficiency (η) about 15.03 %. The conclusions from the results is that the thicker the active layer and the more higher the concentration, the higher the efficiency of the solar cells.

  12. Effects of alkyl chain length and substituent pattern of fullerene bis-adducts on film structures and photovoltaic properties of bulk heterojunction solar cells.

    Science.gov (United States)

    Tao, Ran; Umeyama, Tomokazu; Kurotobi, Kei; Imahori, Hiroshi

    2014-10-01

    A series of alkoxycarbonyl-substituted dihydronaphthyl-based [60]fullerene bis-adduct derivatives (denoted as C2BA, C4BA, and C6BA with the alkyl chain of ethyl, n-butyl, and n-hexyl, respectively) have been synthesized to investigate the effects of alkyl chain length and substituent pattern of fullerene bis-adducts on the film structures and photovoltaic properties of bulk heterojunction polymer solar cells. The shorter alkyl chain length caused lower solubility of the fullerene bis-adducts (C6BA > C4BA > C2BA), thereby resulting in the increased separation difficulty of respective bis-adduct isomers. The device performance based on poly(3-hexylthiophene) (P3HT) and the fullerene bis-adduct regioisomer mixtures was enhanced by shortening the alkyl chain length. When using the regioisomerically separated fullerene bis-adducts, the devices based on trans-2 and a mixture of trans-4 and e of C4BA exhibited the highest power conversion efficiencies of ca. 2.4%, which are considerably higher than those of the C6BA counterparts (ca. 1.4%) and the C4BA regioisomer mixture (1.10%). The film morphologies as well as electron mobilities of the P3HT:bis-adduct blend films were found to affect the photovoltaic properties considerably. These results reveal that the alkyl chain length and substituent pattern of fullerene bis-adducts significantly influence the photovoltaic properties as well as the film structures of bulk heterojunction solar cells.

  13. Material profile influences in bulk-heterojunctions

    OpenAIRE

    Roehling, J.D.; Rochester, C.W.; Ro, H.W.; Wang, P.; Majewski, J; Batenburg, Joost; Arslan, I; Delongchamp, D.M.; Moulé, A.J.

    2014-01-01

    The morphology in mixed bulk-heterojunction films are compared using three different quantitative measurement techniques. We compare the vertical composition changes using high-angle annular dark-field scanning transmission electron microscopy with electron tomography and neutron and x-ray reflectometry. The three measurement techniques yield qualitatively comparable vertical concentration measurements. The presence of a metal cathode during thermal annealing is observed to alter the fulleren...

  14. Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells

    KAUST Repository

    McDowell, Caitlin

    2015-07-14

    The addition of polystyrene (PS), a typical insulator, is empirically shown to increase the power conversion efficiencies (PCEs) of a solution-deposited bulk heterojunction (BHJ) molecular blend film used in solar cell fabrication: p-DTS(FBTTh2)2/PC71BM. The performance is further improved by small quantities of diiodooctane (DIO), an established solvent additive. In this study, how the addition of PS and DIO affects the film formation of this bulk heterojunction blend film are probed via in situ monitoring of absorbance, thickness, and crystallinity. PS and DIO additives are shown to promote donor crystallite formation on different time scales and through different mechanisms. PS-containing films retain chlorobenzene solvent, extending evaporation time and promoting phase separation earlier in the casting process. This extended time is insufficient to attain the morphology for optimal PCE results before the film sets. Here is where the presence of DIO comes into play: its low vapor pressure further extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase long after casting, ultimately leading to the best BHJ organization. In situ measurement shows that polystyrene (PS) and diiodooctane (DIO) additives promote donor crystallite formation synergistically, on different time scales, and through different mechanisms. PS-rich films retain solvent, promoting phase separation early in the casting process. Meanwhile, the low vapor pressure of DIO extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase after casting. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Luminescent GdVO4:Sm3+ quantum dots enhance power conversion efficiency of bulk heterojunction polymer solar cells by Förster resonance energy transfer

    Science.gov (United States)

    Bishnoi, Swati; Gupta, Vinay; Sharma, Chhavi; Haranath, D.; Naqvi, Sheerin; Kumar, Mahesh; Sharma, Gauri D.; Chand, Suresh

    2016-07-01

    In this work, we report enhanced power conversion efficiency (PCE) of bulk heterojunction polymer solar cells by Förster resonance energy transfer (FRET) from samarium-doped luminescent gadolinium orthovanadate (GdVO4:Sm3+) quantum dots (QDs) to polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) polymer. The photoluminescence emission spectrum of GdVO4:Sm3+ QDs overlaps with the absorption spectrum of PTB7, leading to FRET from GdVO4:Sm3+ to PTB7, and significant enhancements in the charge-carrier density of excited and polaronic states of PTB7 are observed. This was confirmed by means of femtosecond transient absorption spectroscopy. The FRET from GdVO4:Sm3+ QDs to PTB7 led to a remarkable increase in the power conversion efficiency (PCE) of PTB7:GdVO4:Sm3+:PC71BM ([6,6]-phenyl-C71-butyric acid methyl ester) polymer solar cells. The PCE in optimized ternary blend PTB7:GdVO4:Sm3+:PC71BM (1:0.1:1.5) is increased to 8.8% from 7.2% in PTB7:PC71BM. This work demonstrates the potential of rare-earth based luminescent QDs in enhancing the PCE of polymer solar cells.

  16. Effect of the Side Chains and Anode Material on Thermal Stability and Performance of Bulk-Heterojunction Solar Cells Using DPP(TBFu2 Derivatives as Donor Materials

    Directory of Open Access Journals (Sweden)

    Alexander Kovalenko

    2015-01-01

    Full Text Available An optimized fabrication of bulk-heterojunction solar cells (BHJ SCs based on previously reported diketopyrrolopyrrole donor, ethyl-hexylated DPP(TBFu2, as well as two new DPP(TBFu2 derivatives with ethyl-hexyl acetate and diethyl acetal solubilizing side-chains and PC60BM as an acceptor is demonstrated. Slow gradual annealing of the solar cell causing the effective donor-acceptor reorganization, and as a result higher power conversion efficiency (PCE, is described. By replacing a hole transporting layer PEDOT:PSS with MoO3 we obtained higher PCE values as well as higher thermal stability of the anode contact interface. DPP(TBFu2 derivative containing ethyl-hexyl acetate solubilizing side-chains possessed the best as-cast self-assembly and high crystallinity. However, the presence of ethyl-hexyl acetate and diethyl acetal electrophilic side-chains stabilizes HOMO energy of isolated DPP(TBFu2 donors with respect to the ethyl-hexylated one, according to cyclic voltammetry.

  17. High-efficiency hole extraction/electron-blocking layer to replace poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) in bulk-heterojunction polymer solar cells

    Science.gov (United States)

    Hains, Alexander W.; Marks, Tobin J.

    2008-01-01

    An anode interfacial layer is reported for bulk-heterojunction (BHJ) polymer solar cells to replace the commonly used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). A poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB)+4,4'-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl (TPDSi2) blend is crosslinked, forming robust ˜10nm thick films covalently bound to indium tin oxide, which transport holes while blocking misdirected electrons. The thermal stability and photovoltaic performance metrics of TFB :TPDSi2-modified BHJ cells are significantly greater than those of cells fabricated in parallel with PEDOT:PSS or with no interfacial layer. For a poly[2-methoxy-5-(3',7'-dimethyloctyloxyl]-1,4-phenylene vinylene: methanofullerene[6 6]-phenyl C61-butyric acid methyl ester cell, Voc=0.89V, Jsc=4.62mA/cm2, FF =54.4%, and ηp=2.23%.

  18. Closed-form expressions correlating exciton transport and interfacial charge carrier generation with the donor/acceptor morphology in organic bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Organic bulk heterojunction (BHJ) solar cells are frequently modeled with effective-medium device models; these models, however, do not resolve the relation between excitonic processes in the donor/acceptor (D/A) blend and the D/A morphology. In this context, we derive a simple analytical model to relate the interfacial exciton flux and the volumetric generation rate of interfacial electron–hole pairs with the morphological characteristics of a D/A blend. Our approach does not require explicit morphological information of the D/A blend, except for the specific interfacial area and the blending ratio between donor and acceptor materials, both of which can be assessed experimentally. The expressions are verified with numerical simulations based on randomly generated three-dimensional D/A morphologies – overall, good agreement is found. The analytical expressions developed in this paper can easily be integrated into existing effective-medium device models, allowing them to capture the effect of exciton transport and morphology on free charge carrier generation in more detail. These expressions potentially allow morphological features in a D/A blend to be optimized within a fast, 1D computational framework

  19. Bulk Heterojunction Solar Cell with Nitrogen-Doped Carbon Nanotubes in the Active Layer: Effect of Nanocomposite Synthesis Technique on Photovoltaic Properties

    Directory of Open Access Journals (Sweden)

    Godfrey Keru

    2015-05-01

    Full Text Available Nanocomposites of poly(3-hexylthiophene (P3HT and nitrogen-doped carbon nanotubes (N-CNTs have been synthesized by two methods; specifically, direct solution mixing and in situ polymerization. The nanocomposites were characterized by means of transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray dispersive spectroscopy, UV-Vis spectrophotometry, photoluminescence spectrophotometry (PL, Fourier transform infrared spectroscopy (FTIR, Raman spectroscopy, thermogravimetric analysis, and dispersive surface energy analysis. The nanocomposites were used in the active layer of a bulk heterojunction organic solar cell with the composition ITO/PEDOT:PSS/P3HT:N-CNTS:PCBM/LiF/Al. TEM and SEM analysis showed that the polymer successfully wrapped the N-CNTs. FTIR results indicated good π-π interaction within the nanocomposite synthesized by in situ polymerization as opposed to samples made by direct solution mixing. Dispersive surface energies of the N-CNTs and nanocomposites supported the fact that polymer covered the N-CNTs well. J-V analysis show that good devices were formed from the two nanocomposites, however, the in situ polymerization nanocomposite showed better photovoltaic characteristics.

  20. Predictive Mechanistic Model for the Electrical Impedance and Intensity-Modulated Photocurrent and Photovoltage Spectroscopic Responses of an Organic Bulk Heterojunction Solar Cell

    Science.gov (United States)

    Set, Ying Ting; Birgersson, Erik; Luther, Joachim

    2016-05-01

    We develop a predictive and mechanistic model for the intensity-modulated photocurrent spectroscopic (IMPS), intensity-modulated photovoltage spectroscopic (IMVS), and electrical impedance spectroscopic (EIS) responses of organic bulk heterojunction (BHJ) solar cells. Unlike the dominant analytical framework—equivalent circuit analysis—the model uses physical parameters that directly reflect the device's fundamental electronic mechanisms, eliminating the ambiguity associated with interpreting phenomenological parameters. Formulated in the frequency domain, the model is a computationally efficient tool for extracting parameters from the measured spectra. With a set of physical parameters representing a device, we predict the device's spectra (a) in techniques employing different methods of perturbing a device and (b) at different bias voltages and illumination intensities. The predicted spectra show good agreement with the measured ones. By quantifying the device's internal electric field and charge carrier concentration and relating them to the spectra, we determine that the IMPS responses at the short-circuit condition and the IMVS responses at the open-circuit condition directly reflect the charge carrier extraction and recombination, respectively. Furthermore, the EIS response indicates the device's recombination time scale at different bias voltages.

  1. P3HT:DiPBI bulk heterojunction solar cells: morphology and electronic structure probed by multiscale simulation and UV/vis spectroscopy.

    Science.gov (United States)

    Winands, Thorsten; Böckmann, Marcus; Schemme, Thomas; Ly, Phong-Minh Timmy; de Jong, Djurre H; Wang, Zhaohui; Denz, Cornelia; Heuer, Andreas; Doltsinis, Nikos L

    2016-02-17

    Coarse grained molecular dynamics simulations are performed for a mixture of poly(3-hexylthiophene) (P3HT) and diperylene bisimide (DiPBI). The effect of different annealing and cooling protocols on the morphology is investigated and the resulting domain structures are analyzed. In particular, π-stacked clusters of DiPBI molecules are observed whose size decreases with increasing temperature. Domain structure and diffusivity data suggest that the DiPBI subsystem undergoes an order → disorder phase transition between 700 and 900 K. Electronic structure calculations based on density functional theory are carried out after backmapping the coarse grained model onto an atomistic force field representation built upon first principles. UV/vis absorption spectra of the P3HT:DiPBI mixture are computed using time-dependent density functional linear response theory and recorded experimentally for a spin-coated thin film. It is demonstrated that the absorption spectrum depends sensitively on the details of the amorphous structure, thus providing valuable insight into the morphology. In particular, the results show that the tempering procedure has a significant influence on the material's electronic properties. This knowledge may help to develop effective processing routines to enhance the performance of bulk heterojunction solar cells. PMID:26853376

  2. The use of thermal initiator to make organic bulk heterojunction solar cells with a good percolation path

    Science.gov (United States)

    Tong, S. W.; Zhang, C. F.; Jiang, C. Y.; Ling, Q. D.; Kang, E. T.; Chan, D. S. H.; Zhu, Chunxiang

    2008-07-01

    A simple method is developed to make an interpenetrating network of poly(3-hexylthiophene-2,5-diyl) (P3HT) and fullerene (C60) by mixing P3HT solution with a thermal initiator 2,2'-azobis(isobutyronitrile) (AIBN). After mild annealing, the release of nitrogen from AIBN increases the roughness of P3HT dramatically. Significant photoluminescence quenching between the roughened donor P3HT and overlaying acceptor C60 is related to the significant increment of donor-acceptor interfacial areas. Based on this interpenetrated network of P3HT/C60, more than threefold increase in the photovoltaic efficiency of devices is achieved compared with bilayer structure. Fill factor is also improved, implying good percolation path in this heterojunction structure.

  3. X-Ray Nanoscopy of a Bulk Heterojunction.

    Directory of Open Access Journals (Sweden)

    Nilesh Patil

    Full Text Available Optimizing the morphology of bulk heterojunctions is known to significantly improve the photovoltaic performance of organic solar cells, but available quantitative imaging techniques are few and have severe limitations. We demonstrate X-ray ptychographic coherent diffractive imaging applied to all-organic blends. Specifically, the phase-separated morphology in bulk heterojunction photoactive layers for organic solar cells, prepared from a 50:50 blend of poly(3-hexylthiophene (P3HT and phenyl-C61-butyric acid methyl ester (PCBM and thermally treated for different annealing times is imaged to high resolution. Moreover, using a fast-scanning calorimetry chip setup, the nano-morphological changes caused by repeated thermal annealing applied to the same sample could be monitored. X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers. The quantitative phase contrast images further allow us to estimate the local volume fraction of PCBM across the photovoltaically active layers. The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates. Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

  4. X-Ray Nanoscopy of a Bulk Heterojunction

    Science.gov (United States)

    Patil, Nilesh; Torbjørn, Eirik; Skjønsfjell, Bakken; Van den Brande, Niko; Chavez Panduro, Elvia Anabela; Claessens, Raf; Guizar-Sicairos, Manuel; Van Mele, Bruno; Breiby, Dag Werner

    2016-07-01

    Optimizing the morphology of bulk heterojunctions is known to significantly improve the photovoltaic performance of organic solar cells, but available quantitative imaging techniques are few and have severe limitations. We demonstrate X-ray ptychographic coherent diffractive imaging applied to all-organic blends. Specifically, the phase-separated morphology in bulk heterojunction photoactive layers for organic solar cells, prepared from a 50:50 blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) and thermally treated for different annealing times is imaged to high resolution. Moreover, using a fast-scanning calorimetry chip setup, the nano-morphological changes caused by repeated thermal annealing applied to the same sample could be monitored. X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers. The quantitative phase contrast images further allow us to estimate the local volume fraction of PCBM across the photovoltaically active layers. The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates. Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

  5. X-Ray Nanoscopy of a Bulk Heterojunction

    Science.gov (United States)

    Skjønsfjell, Eirik Torbjørn Bakken; Van den Brande, Niko; Chavez Panduro, Elvia Anabela; Claessens, Raf; Guizar-Sicairos, Manuel; Van Mele, Bruno; Breiby, Dag Werner

    2016-01-01

    Optimizing the morphology of bulk heterojunctions is known to significantly improve the photovoltaic performance of organic solar cells, but available quantitative imaging techniques are few and have severe limitations. We demonstrate X-ray ptychographic coherent diffractive imaging applied to all-organic blends. Specifically, the phase-separated morphology in bulk heterojunction photoactive layers for organic solar cells, prepared from a 50:50 blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) and thermally treated for different annealing times is imaged to high resolution. Moreover, using a fast-scanning calorimetry chip setup, the nano-morphological changes caused by repeated thermal annealing applied to the same sample could be monitored. X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers. The quantitative phase contrast images further allow us to estimate the local volume fraction of PCBM across the photovoltaically active layers. The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates. Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation. PMID:27367796

  6. p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

    2014-11-25

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

  7. Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Pirotte, Geert; Kesters, Jurgen; Verstappen, Pieter; Govaerts, Sanne; Manca, Jean; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter

    2015-10-12

    Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool. In this contribution, a flow protocol is optimized for the high performance benzodithiophene-thienopyrroledione copolymer PBDTTPD and the material quality is probed through systematic solar-cell evaluation. A stepwise approach is adopted to turn the batch process into a reproducible and scalable continuous flow procedure. Solar cell devices fabricated using the obtained polymer batches deliver an average power conversion efficiency of 7.2 %. Upon incorporation of an ionic polythiophene-based cathodic interlayer, the photovoltaic performance could be enhanced to a maximum efficiency of 9.1 %. PMID:26388210

  8. Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Pirotte, Geert; Kesters, Jurgen; Verstappen, Pieter; Govaerts, Sanne; Manca, Jean; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter

    2015-10-12

    Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool. In this contribution, a flow protocol is optimized for the high performance benzodithiophene-thienopyrroledione copolymer PBDTTPD and the material quality is probed through systematic solar-cell evaluation. A stepwise approach is adopted to turn the batch process into a reproducible and scalable continuous flow procedure. Solar cell devices fabricated using the obtained polymer batches deliver an average power conversion efficiency of 7.2 %. Upon incorporation of an ionic polythiophene-based cathodic interlayer, the photovoltaic performance could be enhanced to a maximum efficiency of 9.1 %.

  9. Increasing the open circuit voltage of bulk-heterojunction solar cells by raising the LUMO level of the acceptor

    NARCIS (Netherlands)

    Kooistra, Floris B.; Knol, Joop; Kastenberg, Fredrik; Popescu, Lacramioara M.; Verhees, Wiljan J. H.; Kroon, Jan M.; Hummelen, Jan C.

    2007-01-01

    We report the synthesis, characterization, and electrochemical properties of ten new fullerene derivatives for usage in organic solar cells. The phenyl ring of PCBM was substituted with electron-donating and electron-withdrawing substituents to study their influence on the LUMO level of the parent f

  10. Correlation between LUMO offset of donor/acceptor molecules to an open circuit voltage in bulk heterojunction solar cell

    International Nuclear Information System (INIS)

    The correlation between the open circuit voltage and the LUMO offset of the donor and acceptor polymers in the bulkheterojunction solar cell was studied for three different thiophene derivatives. The HOMO levels of all the polymers in this investigation were chosen to be similar which results in close values of ΔEDA=EHOMOD−ELUMOA. However, the measured Voc was found to be increasing with decreasing value of the LUMO offset that exists between the donor polymer and fullerene.

  11. Optimizing P3HT/PCBM/MWCNT films for increased stability in polymer bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    The effect of multi-walled carbon nanotubes on the properties of P3HT:PCBM based solar cells has been studied. The concentration of MWCNT was optimized at 0.2% and the concentration of P3HT:PCBM was increased from 20mg/ml to 30mg/ml to obtain highest efficiency. An increase in charge carrier mobility was also observed, which is attributed to high charge transport properties of MWCNT. The active layer was optically stable with respect to absorption, whereas the emission spectra revealed an increase in charge recombination with time. The solar cells doped with MWCNT exhibited increased stability as compared to undoped cells. - Highlights: • MWCNT doped P3HT:PCBM based solar cells are optimized for increased efficiency. • Degradation studies showed that MWCNT stabilizes the cell performance. • Mobility and basic device characteristics decreased with time. • Photoluminescence studies with time showed an increase in charge recombination. • Degradation for devices kept in air is faster as compared to the samples in vacuum

  12. Material Profile Influences in Bulk-Heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Roehling, John D.; Rochester, Christopher W.; Ro, Hyun W.; Wang, Peng; Majewski, Jaroslaw; Batenburg, Kees J.; Arslan, Ilke; Delongchamp, Dean M.; Moule, Adam J.

    2014-10-01

    he morphology in mixed bulk-heterojunction films are compared using three different quantitative measurement techniques. We compare the vertical composition changes using high-angle annular dark-field scanning transmission electron microscopy with electron tomography and neutron and x-ray reflectometry. The three measurement techniques yield qualita-tively comparable vertical concentration measurements. The presence of a metal cathode during thermal annealing is observed to alter the fullerene concentration throughout the thickness of the film for all measurements. However, the abso-lute vertical concentration of fullerene is quantitatively different for the three measurements. The origin of the quantitative measurement differences is discussed. The authors thank Luna Innovations, Inc. for donating the endohedral fullerenes used in this study and Plextronics for the P3HT. They are gratefully thank the National Science Foundation Energy for Sustainability Program, Award No. 0933435. This work benefited from the use of the Lujan Neutron Scattering Center at Los Alamos Neutron Science Center funded by the DOE Office of Basic Energy Sciences and Los Alamos National Laboratory under DOE Contract DE-AC52-06NA25396. This research was also supported in part by Laboratory Directed Research & Development program at PNNL. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy under contract DE-AC05-76RL01830.

  13. Enhancement of short-circuit current density in polymer bulk heterojunction solar cells comprising plasmonic silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuzhao; Lin, Xiaofeng; Ou, Jiemei; Chen, Xudong, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Sun Yat-sen University, Guangzhou 510275 (China); Qing, Jian; Zhong, Zhenfeng; Zhou, Xiang, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn; Chen, Yujie, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Hu, Chenglong [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan 430056 (China)

    2014-03-24

    We demonstrate that the influence of plasmonic effects based on silver nanowires (Ag NWs) on the characteristics of polymer solar cells (PSCs). The solution-processed Ag NWs are situated at the interface of anode buffer layer and active layer, which could enhance the performance especially the photocurrent of PSCs by scattering, localized surface plasmon resonance, and surface plasmon polaritons. Plasmonic effects are confirmed by the enhancement of extinction spectra, external quantum efficiency, and steady state photoluminescence. Consequently, the short-circuit current density (J{sub sc}) and power conversion efficiency enhance about 24% and 18%, respectively, under AM1.5 illumination when Ag NWs plasmonic nanostructure incorporated into PSCs.

  14. Correlation between LUMO offset of donor/acceptor molecules to an open circuit voltage in bulk heterojunction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mola, Genene Tessema, E-mail: mola@ukzn.ac.za [School of. Chemistry and Physics, University of Kwazulu-Natal, Pietermaritzburg Campus, Private Bag X01, Scottsville 3209 (South Africa); Abera, Newayemedhin [Addis Ababa University, Department of Physics, P.O. BOX 1176, Addis Ababa (Ethiopia)

    2014-07-15

    The correlation between the open circuit voltage and the LUMO offset of the donor and acceptor polymers in the bulkheterojunction solar cell was studied for three different thiophene derivatives. The HOMO levels of all the polymers in this investigation were chosen to be similar which results in close values of ΔE{sub DA}=E{sub HOMO}{sup D}−E{sub LUMO}{sup A}. However, the measured V{sub oc} was found to be increasing with decreasing value of the LUMO offset that exists between the donor polymer and fullerene.

  15. Silicon heterojunction solar cells

    CERN Document Server

    Fahrner, W R; Neitzert, H C

    2006-01-01

    The world of today must face up to two contradictory energy problems: on the one hand, there is the sharply growing consumer demand in countries such as China and India. On the other hand, natural resources are dwindling. Moreover, many of those countries which still possess substantial gas and oil supplies are politically unstable. As a result, renewable natural energy sources have received great attention. Among these, solar-cell technology is one of the most promising candidates. However, there still remains the problem of the manufacturing costs of such cells. Many attempts have been made

  16. Use of a commercially available nucleating agent to control the morphological development of solution-processed small molecule bulk heterojunction organic solar cells

    KAUST Repository

    Sharenko, Alexander

    2014-08-12

    © the Partner Organisations 2014. The nucleating agent DMDBS is used to modulate the crystallization of solution-processed small molecule donor molecules in bulk heterojunction organic photovoltaic (BHJ OPV) devices. This control over donor molecule crystallization leads to a reduction in optimized thermal annealing times as well as smaller donor molecule crystallites, and therefore more efficient devices, when using an excessive amount of solvent additive. We therefore demonstrate the use of nucleating agents as a powerful and versatile processing strategy for solution-processed, small molecule BHJ OPVs. This journal is

  17. The Impact of Grain Alignment of the Electron Transporting Layer on the Performance of Inverted Bulk Heterojunction Solar Cells.

    Science.gov (United States)

    Murali, Banavoth; Labban, Abdulrahman El; Eid, Jessica; Alarousu, Erkki; Shi, Dong; Zhang, Qiang; Zhang, Xixiang; Bakr, Osman M; Mohammed, Omar F

    2015-10-21

    This report presents a new strategy for improving solar cell power conversion efficiencies (PCEs) through grain alignment and morphology control of the ZnO electron transport layer (ETL) prepared by radio frequency (RF) magnetron sputtering. The systematic control over the ETL's grain alignment and thickness is shown, by varying the deposition pressure and operating substrate temperature during the deposition. Notably, a high PCE of 6.9%, short circuit current density (J(sc)) of 12.8 mA cm(-2), open circuit voltage (V(oc)) of 910 mV, and fill factor of 59% are demonstrated using the poly(benzo[1,2-b:4,5-b']dithiophene-thieno[3,4-c]pyrrole-4,6-dione):[6,6]-phenyl-C(71) -butyric acid methyl ester polymer blend with ETLs prepared at room temperature exhibiting oriented and aligned rod-like ZnO grains. Increasing the deposition temperature during the ZnO sputtering induces morphological cleavage of the rod-like ZnO grains and therefore reduced conductivity from 7.2 × 10(-13) to ≈1.7 × 10(-14) S m(-1) and PCE from 6.9% to 4.28%. An investigation of the charge carrier dynamics by femtosecond (fs) transient absorption spectroscopy with broadband capability reveals clear evidence of faster carrier recombination for a ZnO layer deposited at higher temperature, which is consistent with the conductivity and device performance.

  18. The Impact of Grain Alignment of the Electron Transporting Layer on the Performance of Inverted Bulk Heterojunction Solar Cells

    KAUST Repository

    Banavoth, Murali

    2015-08-13

    This report presents a new strategy for improving solar cell power conversion efficiencies (PCEs) through grain alignment and morphology control of the ZnO electron transport layer (ETL) prepared by radio frequency (RF) magnetron sputtering. The systematic control over the ETL\\'s grain alignment and thickness is shown, by varying the deposition pressure and operating substrate temperature during the deposition. Notably, a high PCE of 6.9%, short circuit current density (Jsc) of 12.8 mA cm-2, open circuit voltage (Voc) of 910 mV, and fill factor of 59% are demonstrated using the poly(benzo[1,2-b:4,5-b\\']dithiophene-thieno[3,4-c]pyrrole-4,6-dione):[6,6]-phenyl-C71-butyric acid methyl ester polymer blend with ETLs prepared at room temperature exhibiting oriented and aligned rod-like ZnO grains. Increasing the deposition temperature during the ZnO sputtering induces morphological cleavage of the rod-like ZnO grains and therefore reduced conductivity from 7.2 × 10-13 to ≈1.7 × 10-14 S m-1 and PCE from 6.9% to 4.28%. An investigation of the charge carrier dynamics by femtosecond (fs) transient absorption spectroscopy with broadband capability reveals clear evidence of faster carrier recombination for a ZnO layer deposited at higher temperature, which is consistent with the conductivity and device performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Efficient organic photovoltaic cells with vertically ordered bulk heterojunctions.

    Science.gov (United States)

    Yu, Bo; Wang, Haibo; Yan, Donghang

    2013-12-01

    Nanoscale morphology has been proved to be the key parameter deciding the exciton dissociation and charge transportation in bulk heterojunction (BHJ) solar cells. In this paper, we report a kind of small molecular organic photovoltaic cell (OPV) with a vertically ordered BHJ prepared by the weak epitaxial growth method. By this method, zinc phthalocyanine (ZnPc) can easily be formed into a highly ordered and continuous thin film and C60 is inclined to become dispersed crystalline grains in ZnPc film. Furthermore, we can control both the size and distribution density of C60 crystalline grains in ZnPc thin film without destroying the order of the ZnPc thin film. The OPVs with the vertically ordered BHJ show a high fill factor and a power conversion efficiency over 3% has been achieved.

  20. Effect of ligand exchange of Cu{sub 2}ZnSnS{sub 4} nanocrystals on the charge transport and photovoltaic performance of nanostructured depleted bulk heterojunction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuo-Xi; Zhou, Zheng-Ji, E-mail: zzj@henu.edu.cn; Bai, Bing; Liu, Ming-Hua; Zhou, Wen-Hui; Kou, Dong-Xing; Wu, Si-Xin, E-mail: wusixin@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of Ministry of Education (China)

    2015-12-15

    Cu{sub 2}ZnSnS{sub 4} (CZTS) nanocrystals combining the advantage of feasible solution-phase synthesis and processing are perceived as promising materials for application in efficient, low-cost photovoltaic technology. Herein, we have got surfactant-free CZTS nanocrystals by a novel ligand exchange method, and the obtained CZTS nanocrystals were deposited onto ZnO nanorod arrays to construct depleted bulk heterojunction solar cell. The all-inorganic CZTS nanocrystal solar cells demonstrated a remarkable improvement in J{sub sc} (from 8.14 to 13.97 mA/cm{sup 2}) and power conversion efficiency (from 1.83 to 3.34 %) compared with surfactant-capped CZTS nanocrystals. Using surface photovoltage spectrum, the influence of ligand exchange of CZTS nanocrystals on the charge transport and photovoltaic performance of the nanostructured CZTS solar cells was discussed.

  1. Amorphous silicon crystalline silicon heterojunction solar cells

    CERN Document Server

    Fahrner, Wolfgang Rainer

    2013-01-01

    Amorphous Silicon/Crystalline Silicon Solar Cells deals with some typical properties of heterojunction solar cells, such as their history, the properties and the challenges of the cells, some important measurement tools, some simulation programs and a brief survey of the state of the art, aiming to provide an initial framework in this field and serve as a ready reference for all those interested in the subject. This book helps to ""fill in the blanks"" on heterojunction solar cells. Readers will receive a comprehensive overview of the principles, structures, processing techniques and the curre

  2. Ambipolar all-polymer bulk heterojunction field-effect transistors

    NARCIS (Netherlands)

    Szendrei, Krisztina; Jarzab, Dorota; Chen, Zhihua; Facchetti, Antonio; Loi, Maria A.

    2010-01-01

    We demonstrate solution processable all-polymer based field-effect transistors (FETs) exhibiting comparable electron and hole mobilities. The semiconducting layer is a bulk heterojunction of poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}

  3. Effect of the Phosphorus Gettering on Si Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Hyomin Park

    2012-01-01

    Full Text Available To improve the efficiency of crystalline silicon solar cells, should be collected the excess carrier as much as possible. Therefore, minimizing the recombination both at the bulk and surface regions is important. Impurities make recombination sites and they are the major reason for recombination. Phosphorus (P gettering was introduced to reduce metal impurities in the bulk region of Si wafers and then to improve the efficiency of Si heterojunction solar cells fabricated on the wafers. Resistivity of wafers was measured by a four-point probe method. Fill factor of solar cells was measured by a solar simulator. Saturation current and ideality factor were calculated from a dark current density-voltage graph. External quantum efficiency was analyzed to assess the effect of P gettering on the performance of solar cells. Minority bulk lifetime measured by microwave photoconductance decay increases from 368.3 to 660.8 μs. Open-circuit voltage and short-circuit current density increase from 577 to 598 mV and 27.8 to 29.8 mA/cm2, respectively. The efficiency of solar cells increases from 11.9 to 13.4%. P gettering will be feasible to improve the efficiency of Si heterojunction solar cells fabricated on P-doped Si wafers.

  4. Structure and properties of nano-confined poly(3-hexylthiophene) in nano-array/polymer hybrid ordered-bulk heterojunction solar cells

    Science.gov (United States)

    Foong, Thelese Ru Bao; Chan, Khai Leok; Hu, Xiao

    2012-01-01

    The ordered-bulk heterojunction (BHJ) photovoltaic device comprising a semiconducting donor polymer incorporated into pristine/unmodified vertically aligned arrays of metal oxide acceptor nanotubes/nanorods is widely perceived as being structurally ideal for energy conversion but the power conversion efficiencies of such devices remain relatively low (in the order of η = 0.6%) when compared with bilayer or non-ordered bulk heterojunction systems. We explain the incongruity by investigating the morphology and microstructure of regio-regular poly(3-hexyl thiophene) (P3HT) infiltrated and confined within the cavities of TiO2 nanotube arrays. A series of TiO2 nanotube arrays with different nanotube diameters and inter-nanotube spacings are fabricated by the liquid-phase atomic layer deposition (LALD) technique, and P3HT is infiltrated into the array cavities via a vacuum-annealing technique. X-Ray diffraction studies reveal that the P3HT chains in both nano-confined and non-confined (i.e. planar film) environments are well-aligned and oriented edge-on with respect to the underlying substrate. Up to 2.5-fold improvement in the incident-photon-to-converted-electron efficiency (IPCE) is observed in ordered-BHJ structures over benchmark planar devices which we attribute to the increase in interfacial area resulting from the use of the nanostructures. However, the large effective surface area conferred by the nano-arrays (up to 9.5 times that of the planar system) suggests that much higher efficiencies could be harnessed. Our study shows that the morphology and orientation of the infiltrated polymer play a critical role in the charge transport of the device, and suggests that better understanding and control of polymer morphology under nano-confinement in the nano-array will be the key to fully reaping the promised benefit of ordered-BHJ devices.The ordered-bulk heterojunction (BHJ) photovoltaic device comprising a semiconducting donor polymer incorporated into pristine

  5. Epitaxy-assisted creation of PCBM nanocrystals and its application in constructing optimized morphology for bulk-heterojunction polymer solar cells.

    Science.gov (United States)

    Li, Ligui; Lu, Guanghao; Li, Sijun; Tang, Haowei; Yang, Xiaoniu

    2008-12-11

    PCBM (a C60 derivative) is so far the most successful electron acceptor for bulk-heterojunction polymer photovoltaic (PV) cells. Here we present a novel method epitaxy-assisted creation of PCBM nanocrystals and their homogeneous distribution in the matrix using freshly cleaved mica sheet as the substrate. The highly matched epitaxy relationship between the unit cell of PCBM crystal and crystallographic (001) surface of mica induces abundant PCBM nuclei, which subsequently develop into nanoscale crystals with homogeneous dispersion in the composite film. Both the shape and size of these nanocrystals could be tuned via choosing the type of matrix polymer, film thickness, ratio of PCBM in the composite film, and annealing temperature. Thus, the obtained thin composite film is removed from the original mica substrate via the flotation technique and transferred to a real substrate for device completion. The success of this method has been verified by the substantially improved device performance, in particular the increased short-circuit current, which is heavily dependent on the morphology of the photoactive layer. Therefore, we have actually demonstrated a novel approach to construct preferred morphology for high-performance optoelectronic devices via resorting to other specific substrates which could induce the formation of this type morphology. PMID:19367916

  6. Interfacial Energy Alignment at the ITO/Ultra-Thin Electron Selective Dielectric Layer Interface and Its Effect on the Efficiency of Bulk-Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Itoh, Eiji; Goto, Yoshinori; Saka, Yusuke; Fukuda, Katsutoshi

    2016-04-01

    We have investigated the photovoltaic properties of an inverted bulk heterojunction (BHJ) cell in a device with an indium-tin-oxide (ITO)/electron selective layer (ESL)/P3HT:PCBM active layer/MoOx/Ag multilayered structure. The insertion of only single layer of poly(diallyl-dimethyl-ammonium chloride) (PDDA) cationic polymer film (or poly(ethyleneimine) (PEI) polymeric interfacial dipole layer) and titanium oxide nanosheet (TN) films as an ESL effectively improved cell performance. Abnormal S-shaped curves were observed in the inverted BHJ cells owing to the contact resistance across the ITO/active layer interface and the ITO/PDDA/TN/active layer interface. The series resistance across the ITO/ESL interface in the inverted BHJ cell was successfully reduced using an interfacial layer with a positively charged surface potential with respect to ITO base electrode. The positive dipole in PEI and the electronic charge phenomena at the electrophoretic deposited TN (ED-TN) films on ITO contributed to the reduction of the contact resistance at the electrode interface. The surface potential measurement revealed that the energy alignment by the transfer of electronic charges from the ED-TN to the base electrodes. The insertion of the ESL with a large positive surface potential reduced the potential barrier for the electron injection at ITO/TN interface and it improved the photovoltaic properties of the inverted cell with an ITO/TN/active layer/MoOx/Ag structure. PMID:27451612

  7. Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers

    Science.gov (United States)

    Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

    We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

  8. Copper phthalocyanine and metal free phthalocyanine bulk heterojunction photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Farooq, Amjad, E-mail: amjad.farooq1212@hotmail.com [Wah Engineering College, University of Wah, Wah Cantt. 47040 (Pakistan); GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Karimov, Kh.S. [GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Physical Technical Institute, Aini St. 299/1, Dushanbe 734063 (Tajikistan); Ahmed, Nisar; Ali, Taimoor [GIK Institute of Engineering Sciences and Technology, Topi 23640, Swabi (Pakistan); Khalid Alamgir, M. [National Institute of Vacuum Science and Technology, NCP complex, Islamabad 44000 (Pakistan); Usman, Muhammad [Experimental Physics Laboratories, National Centre for Physics, Quaid-i-Azam University, Islamabad 44000 (Pakistan)

    2015-01-15

    In this study we present the dependence of electrical properties of copper phthalocyanine (CuPc) and metal free phthalocyanine (H{sub 2}Pc) bulk heterojunction structure under different illumination levels. To fabricate the device on ITO coated glass substrate the bulk heterojunction thin film of CuPc and H{sub 2}Pc with thickness varying from 100 nm to 300 nm are deposited by thermal evaporator. Aluminum thin film was deposited by thermal evaporation as a top contact. The optical properties of the fabricated device are investigated using UV–vis spectroscopy. The current-voltage characteristics in dark and under illumination show that the device is sensitive towards visible light. The absorption spectrum describes its photo sensitivity in the range of wavelength from 200 nm to 850 nm. Simulation of current-intensity of light curve is carried out and experimental results are found in good agreement with simulated ones.

  9. Organic bulk heterojunction photovoltaic structures: design, morphology and properties

    International Nuclear Information System (INIS)

    Main approaches to the design of organic bulk heterojunction photovoltaic structures are generalized and systematized. Novel photovoltaic materials based on fullerenes, organic dyes and related compounds, graphene, conjugated polymers and dendrimers are considered. The emphasis is placed on correlations between the chemical structure and properties of materials. The effect of morphology of the photoactive layer on the photovoltaic properties of devices is analyzed. Main methods of optimization of the photovoltaic properties are outlined. The bibliography includes 338 references

  10. Synthesis of a modified PC{sub 70}BM and its application as an electron acceptor with poly(3-hexylthiophene) as an electron donor for efficient bulk heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Surya Prakash; Kumar, C. Pavan [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad (India); Sharma, G.D. [R and D Centre for Engineering and Science, Jaipur Engineering College, Kukas, Jaipur, Rajasthan (India); Kurchania, Rajnish [Department of Physics, Maulana Azad National Institute of Technology (MANIT), Bhopal (India); Roy, M.S. [Defence Laboratory, Jodhpur (Rajasthan) (India)

    2012-10-10

    A simple and effective modification of phenyl-C{sub 70}-butyric acid methyl ester (PC{sub 70}BM) is carried out in a single step after which the material is used as electron acceptor for bulk heterojunction polymer solar cells (PSCs). The modified PC{sub 70}BM, namely CN-PC{sub 70}BM, showed broader and stronger absorption in the visible region (350-550 nm) of the solar spectrum than PC{sub 70}BM because of the presence of a cyanovinylene 4-nitrophenyl segment. The lowest unoccupied molecular energy level (LUMO) of CN-PC{sub 70}BM is higher than that of PC{sub 70}BM by 0.15 eV. The PSC based on the blend (cast from tetrahydrofuran (THF) solution) consists of P3HT as the electron donor and CN-PC{sub 70}BM as the electron acceptor and shows a power conversion efficiency (PCE) of 4.88%, which is higher than that of devices based on PC{sub 70}BM as the electron acceptor (3.23%). The higher PCE of the solar cell based on P3HT:CN-PC{sub 70}BM is related to the increase in both the short circuit current (J{sub sc}) and the open circuit voltage (V{sub oc}). The increase in J{sub sc} is related to the stronger light absorption of CN-PC{sub 70}BM in the visible region of the solar spectrum as compared to that of PC{sub 70}BM. In other words, more excitons are generated in the bulk heterojunction (BHJ) active layer. On the other hand, the higher difference between the LUMO of CN-PC{sub 70}BM and the HOMO of P3HT causes an enhancement in the V{sub oc}. The addition of 2% (v/v) 1-chloronapthalene (CN) to the THF solvent during film deposition results in an overall improvement of the PCE up to 5.83%. This improvement in PCE can be attributed to the enhanced crystallinity of the blend (particularly of P3HT) and more balanced charge transport in the device. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Chloroboron (III) subnaphthalocyanine as an electron donor in bulk heterojunction photovoltaic cells

    International Nuclear Information System (INIS)

    In this work, chloroboron (III) subnaphthalocyanine (SubNc) was used as an electron donor, combined with a [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) or fullerene C70 acceptor in bulk heterojunction photovoltaic cells. In spite of the limited solubility of SubNc in organic solvents, the solution processed device exhibited an efficiency of 4.0% under 1 sun, AM1.5G solar irradiation at room temperature, and 5.0% at 80 ° C due to the temperature-dependence of the carrier mobilities. SubNc:C70 bulk heterojunctions were also fabricated via thermal co-evaporation, demonstrating an efficiency of 4.4%. This result shows that SubNc is a promising material for photovoltaic applications via various processing techniques, such as vacuum deposition and wet coating. (paper)

  12. Morphology control of a polythiophene-fullerene bulk heterojunction for enhancement of the high-temperature stability of solar cell performance by a new donor-acceptor diblock copolymer

    International Nuclear Information System (INIS)

    A well defined diblock copolymer (P3HT-b-C60) based on regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was synthesized via two controlled polymerization steps and used as a compatibilizer for the P3HT/PCBM blend, which has widely been used as an active layer in bulk heterojunction polymer solar cells. The addition of a small amount of P3HT-b-C60 results in not only the reduction of phase size of P3HT/PCBM blend but also the suppression of macrophase separation for long-time thermal annealing owing to the preferential location of the diblock copolymers at the interface between P3HT and PCBM phases. The morphology change with the annealing time is closely related to the change of the power conversion efficiency (PCE) of solar cells: the PCE of P3HT/PCBM greatly decreases with increasing annealing time while the addition of P3HT-b-C60 significantly reduces the decrease of PCE for long-time thermal annealing.

  13. Visible Light Communication System Using an Organic Bulk Heterojunction Photodetector

    Directory of Open Access Journals (Sweden)

    Cristina de Dios

    2013-09-01

    Full Text Available A visible light communication (VLC system using an organic bulk heterojunction photodetector (OPD is presented. The system has been successfully proven indoors with an audio signal. The emitter consists of three commercial high-power white LEDs connected in parallel. The receiver is based on an organic photodetector having as active layer a blend of poly(3-hexylthiophene (P3HT and phenyl C61-butyric acid methyl ester (PCBM. The OPD is opto-electrically characterized, showing a responsivity of 0.18 A/W and a modulation response of 790 kHz at −6 V.

  14. Photovoltage analysis of a heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Xiong Chao; Yao Ruo-He; Geng Kui-Wei

    2011-01-01

    According to the p-n junction model of Shockley, the relationship between the equilibrium carrier concentrations of n-type and p-type semiconductors on the edges of the depletion region of a p-n junction solar cell is analysed. The calculation results show that the photovoltage can exceed the built-in voltage for a special kind of heterojunction solar cell. When the photovoltage exceeds the built-in voltage under illumination, the dark current and the photocurrent are impeded by the peak of voltage barrier at the interface and the expression of the total Ⅰ-Ⅴ characteristic is given.

  15. 溶剂添加剂对体异质结太阳能电池的影响%The Influence of Solvent Additive on Bulk Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    代科; 钟建; 高娟; 俞江涛; 张霖; 陈久乐

    2012-01-01

    Thanks to its high efficiency,bulk hetero-junction solar cell has drawn great at-tention. Additive DIO is applied to MEH-PPV:PCBM to improve the nanomorphology of the ac-tive layer. The short circuit current reaches the largest (JBC = 8. 74 mA/cm2) when the consisten-cy of DIO is 20 mg/ml,and the device efficiency the highest (PCE=2. 44%),55. 4% higher than that without DIO.%体异质结太阳电池因其高效率特点受到了研究者的极大关注.使用添加剂DIO应用于MEH-PPV:PCBM结构中,改善活性层形貌.最终得到了在DIO浓度为20 mg/ml的时候器件短路电流密度最大(Jsc=8.74 mA/cm2),器件效率最高(PCE=2.44%),相比没有使用DIO的情况效率提升了55.4%.

  16. Synergetic Enhancement of Device Efficiency in Poly(3-hexylthiophene-2,5-diyl/[6,6]-phenyl C61 Butyric Acid Methyl Ester Bulk Heterojunction Solar Cells by Glycerol Addition in the Active Layer

    Directory of Open Access Journals (Sweden)

    Bobins Augustine

    2015-01-01

    Full Text Available Poly(3-hexylthiophene-2,5-diyl(P3HT:[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM is the widely used active layer for the bulk heterojunction solar cells. Annealing is essential for P3HT:PC60BM active layer, since it facilitates the creation of better network for the transfer of the charge carriers. However, the PC60BM in the active layer can crystallize excessively during annealing treatments and disrupt the favorable morphology by forming crystallites in micrometer ranges, thus reducing device efficiency. In this paper we used glycerol as an additive in the active layer. Due to high boiling point of glycerol, it makes slow drying of the active layer possible during the annealing. It thus gives enough time to both electron donor (P3HT and electron acceptor (PC60BM components of the active layer to self-organize and also restrict the crystal overgrowth of PC60BM. Further, the glycerol additive makes the active layer smoother, which may also improve adhesion between the electrode and the active layer. The devices with the pristine active layer showed a power conversion efficiency (PCE of about 2.1% and, with the addition of 30 vol% of glycerol in the active layer, the PCE value increased to 3%.

  17. Cohesion and device reliability in organic bulk heterojunction photovoltaic cells

    KAUST Repository

    Brand, Vitali

    2012-04-01

    The fracture resistance of P3HT:PC 60BM-based photovoltaic devices are characterized using quantitative adhesion and cohesion metrologies that allow identification of the weakest layer or interface in the device structure. We demonstrate that the phase separated bulk heterojunction layer is the weakest layer and report quantitative cohesion values which ranged from ∼1 to 20 J m -2. The effects of layer thickness, composition, and annealing treatments on layer cohesion are investigated. Using depth profiling and X-ray photoelectron spectroscopy on the resulting fracture surfaces, we examine the gradient of molecular components through the thickness of the bulk heterojunction layer. Finally, using atomic force microscopy we show how the topography of the failure path is related to buckling of the metal electrode and how it develops with annealing. The research provides new insights on how the molecular design, structure and composition affect the cohesive properties of organic photovoltaics. © 2011 Elsevier B.V. All rights reserved.

  18. Determination of energy levels in organic bulk-heterojunction systems

    Energy Technology Data Exchange (ETDEWEB)

    Wetzstein, Holger; Krause, Stefan; Schoell, Achim; Reinert, Friedrich [Experimental Physics VII, Julius-Maximilians-University of Wuerzburg, D-97074 Wuerzburg (Germany); Liedtke, Moritz; Kern, Julia; Deibel, Carsten [Experimental Physics VI, Julius-Maximilians-University of Wuerzburg, D-97074 Wuerzburg (Germany)

    2010-07-01

    In order to improve the efficiency of electronic devices based on organic semiconducting materials the detailed knowledge about the exact position of the energy levels responsible for charge transport is crucial. The experimental determination is particularly complicated for bulk heterojunctions of p- and n-conducting materials in terms of sample preparation, film morphology and distinction of the different spectroscopic signatures. We investigated four promising materials for organic photovoltaic devices: the electron donor poly(3-hexylthiophene-2,5-diyl) (P3HT) and the three electron acceptors [6,6]-phenyl-C{sub 61} butyric acid methyl ester (PC{sub 60}BM), its bisadduct analogue (bis- PC{sub 60}BM) and [6,6]-phenyl-C{sub 71} butyric acid methyl ester (PC{sub 70}BM). Thin films of pristine materials as well as bulk heterojunction samples of P3HT:PC{sub 60}BM, P3HT:bis-PC{sub 60}BM and P3HT:PC{sub 70}BM were examined with respect to their valence levels using ultraviolet photoelectron spectroscopy (UPS).

  19. Efficient Perovskite-organic Bulk Heterojunction Hybrid Integrated Solar Cells%高效钙钛矿-有机本体异质结杂化串联太阳能电池

    Institute of Scientific and Technical Information of China (English)

    唐彤; 左红文; 王亚凌; 秦文静; 曹焕奇; 杨利营; 姚聪; 葛子义; 印寿根

    2015-01-01

    An integrated perovskite/organic bulk-heterojunction ( BHJ) photovoltaic device was fabricated for effi-cient light harvesting and energy conversion. The structure of the solar cells consists of two photovoltaic layers, name-ly a methylammonium lead iodide ( CH3 NH3 PbI3 ) and poly ( 3-hexylthiophene ) ( P3HT ) blended with metha-nofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) organic BHJ active layer. The power conversion ef-ficiency (PCE) of 6. 54% was achieved in the integrated device with a Jsc of 19. 14 mA /cm2, a Voc of 0. 76 V, and a FF of 45. 0%. Compared to that of CH3 NH3 PbI3/PCBM planar device, the enhanced performance indicates that the BHJ film absorbs light and contributes to the current density of the device. Our research further demonstrates the compatibility and synergistic potential of the perovskite and organic bulk-heterojunction ( BHJ) photovoltaic device.%制备了一种有机铅卤钙钛矿-有机本体异质结杂化串联太阳能电池。采用紫外可见吸收光谱、原子力显微镜对薄膜形貌进行了表征。结果表明:有机本体异质结层可以有效改善钙钛矿的表面形貌,增强了可见光的吸收。优化后的串联结构电池的短路电流可达19.14 mA /cm2,开路电压为0.76 V,光电转换效率达到了6.54%。钙钛矿电池和有机本体异质结电池串联结构可以同时提高短路电流及填充因子,二者具有较好的相容性和协同作用。

  20. Improved charge transport in P3HT:PCBM bulk heterojunction PV cell under ambient environment

    Energy Technology Data Exchange (ETDEWEB)

    Bell, July T.; Mola, Genene T., E-mail: mola@ukzn.ac.za

    2014-03-15

    Enhanced current density has been observed from P3HT:PCBM bulk heterojunction solar cell after a well sonicated solution was diluted with fresh chloroform solvent. The preparation of the devices was carried out in a simple laboratory environment without glove box and clean room. As the result of such current surge in the devices the efficiency has risen more than double compared to those devices without dilution of the P3HT:PCBM solution. We have recorded an average power conversion efficiency of 4.02(5)% under this condition. This is an encouraging development toward achieving low cost organic photovoltaic devices.

  1. Modeling of Silicon Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Luppina, P.; Lugli, P.; Goodnick, S.

    2015-06-14

    Here we present modeling results on crystalline Si/amorphous Si (a-Si) heterojunction solar cells using Sentaurus including various models for defect states in the a-Si barriers, as well as explicit models for the ITO emitter contact. We investigate the impact of the band offsets and barrier heights of the a-Si/c-Si interface, particularly in terms of the open circuit voltage. It is also shown that the solar cell performance is sensitively dependent on the quality of the a-Si in terms of defect states and their distribution, particularly on the emitter side. Finally, we have investigate the role of tunneling and thermionic emission across the heterointerface in terms of transport from the Si to the ITO contact layer

  2. Optimalization activity of ZnO NR/TiO2 NR-P3HT as an active layer based on hybrid bulk heterojunction on dye sensitized solar cell (DSSC)

    Science.gov (United States)

    Saputri, Liya Nikmatul Maula Zulfa; Ramelan, Ari Handono; Hanif, Qonita Awliya; Hasanah, Yesi Ihdina Fityatal; Prajanira, Lau Bekti; Wahyuningsih, Sayekti

    2016-04-01

    Dye sensitized solar cell (DSSC) with metal inorganic and conjugated organic polymer mixture, ZnO NR/TiO2 NR-P3HT as an active layer based on hybrid bulk heterojunction has been studied. The hybrid material was used to optimize DSSC performs for better efficiency than only TiO2 as an electrode. Synthesis of TiO2 nanorods (NR) was conducted by ball milling 1000 rpm for 4 hours and strong base reaction by hydrothermal process at 120 °C overnight. And the ZnO NR was synthesized from Zn(NO3)2.4H2O precusor by hydrotermal process at 90 °C for 5 hours and calcined on various temperature s of 400, 600, and 800 °C. ZnO NR was coated into an Tndium Tin Oxide (TTO) glass to collecting electron s effectively, where TiO2 NR were incorporated with poly(3 -hexylthiophene) (P3HT) on various concentration s of 5, 10, 15 mg/mL to obtain a larger surface area. Material characterization were performed by X -Ray Diffraction (XRD) and Uv-Vis spectrophotometer. For an application of DSSC were measured by T-V Keithley Multimeter and the efficiency of DSSC at various P3HT's concentrations of 5, 10, 15 mg/mL were 7.44 × 10-3, 0.0114, 0.0104, respectively. The maximum efficiency of DSSC was showed when TiO2 NR-P3HT's concentration was 10 mg/mL.

  3. Benzo[1,2-b:4,5-b’]dithiophene-Pyrido[3,4-b]pyrazine Small-Molecule Donors for Bulk Heterojunction Solar Cells

    KAUST Repository

    Wolf, Jannic

    2016-01-22

    We report on the synthesis, material properties and BHJ solar cell characteristics of a set of π-conjugated small-molecule (SM) donors composed of benzo[1,2-b:4,5-b′]dithiophene (BDT) and pyrido[3,4-b]pyrazine (PP) units – examining the perspectives of alkyl-substituted PP acceptor motifs in SM designs. In these systems (SM1-4), both the type of side chains derived from the PP motifs and the presence of ring-substituents on BDT critically impact (i) molecular packing, and (ii) thin-film morphologies and charge transport in BHJ solar cells. With the appropriate side-chain pattern, the ring-substituted analogue SM4 stands out: achieving efficiencies of ca. 6.5% with PC71BM, and fine-scale morphologies comparable to those obtained with some of the best-performing polymer donors in BHJ solar cells. 1H-1H DQ-SQ NMR analyses are used to examine the distinct self-assembly pattern of SM4, expected to factor into the development of the BHJ morphology.

  4. Remarkably High Conversion Efficiency of Inverted Bulk Heterojunction Solar Cells: From Ultrafast Laser Spectroscopy and Electron Microscopy to Device Fabrication and Optimization

    KAUST Repository

    Alsulami, Qana

    2016-04-10

    In organic donor-acceptor systems, ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) are key determinants of the overall performance of photovoltaic devices. However, a profound understanding of these photophysical processes at device interfaces remains superficial, creating a major bottleneck that circumvents advancements and the optimization of these solar cells. Here, results from time-resolved laser spectroscopy and high-resolution electron microscopy are examined to provide the fundamental information necessary to fabricate and optimize organic solar cell devices. In real time, CT and CS are monitored at the interface between three fullerene acceptors (FAs) (PC71BM, PC61BM, and IC60BA) and the PTB7-Th donor polymer. Femtosecond transient absorption (fs-TA) data demonstrates that photoinduced electron transfer from the PTB7-Th polymer to each FA occurs on the sub-picosecond time scale, leading to the formation of long-lived radical ions. It is also found that the power conversion efficiency improves from 2% in IC60BA-based solar cells to >9% in PC71BM-based devices, in support of our time-resolved results. The insights reported in this manuscript provide a clear understanding of the key variables involved at the device interface, paving the way for the exploitation of efficient CS and subsequently improving the photoconversion efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. GaP/Si heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Saive, R.; Chen, C.; Emmer, H.; Atwater, H.

    2015-05-11

    Improving the efficiency of solar cells requires the introduction of novel device concepts. Recent developments have shown that in Si solar cell technology there is still room for tremendous improvement. Using the heterojunction with intrinsic thin layer (HIT) approach 25.6 % power conversion efficiency was achieved. However, a-Si as a window and passivation layer comes with disadvantages as a-Si shows low conductivity and high parasitic absorption. Therefore, it is likely that using a crystalline material as window layer with high band gab and high mobility can further improve efficiency. We have studied GaP grown by MOCVD on Si with (001) and (112) orientation. We obtained crystalline layers with carrier mobility around 100 cm2/Vs and which passivate Si as confirmed by carrier lifetime measurements. We performed band alignment studies by X-ray photoelectron spectroscopy yielding a valence band offset of 0.3 eV. Comparing this value with the Schottky-model leads to an interface dipole of 0.59 eV. The open circuit voltage increases with increasing doping and is consistent with the theoretical open circuit voltage deduced from work function difference and interface dipole. We obtain an open circuit voltage of 0.38 V for n-doped GaP with doping levels in the order of 10^17 1/cm^3. In our next steps we will increase the doping level further in order to gain higher open circuit voltage. We will discuss the implications of these findings for GaP/Si heterojunction solar cells.

  6. Bulk heterojunction organic photovoltaics from water-processable nanomaterials and their facile fabrication approaches.

    Science.gov (United States)

    Subianto, Surya; Dutta, Naba; Andersson, Mats; Choudhury, Namita Roy

    2016-09-01

    Organic thin film photovoltaics based on bulk-heterojunction donor-acceptor combinations have received significant interest due to their potential for low-cost, large-scale solution processing. However, current state-of-the-art cells utilise materials soluble mainly in halogenated solvents which pose processing challenges due to their toxicity and thus environmental hazards. In this contribution, we look at various nanomaterials, and alternative processing of these solar cells using environmentally friendly solvents, and review recently reported different strategies and approaches that are making inroads in this field. Specifically, we focus on the use of water-dispersible donors and acceptors, use of aqueous solvents for fabrication and discuss the merits of the two main approaches of water-processable solar cells; namely, through the use of water-soluble materials and the use of aqueous dispersion rather than a solution, as well as review some of the recent advances in alternative fabrication techniques.

  7. Novel indolin-2-one-substituted methanofullerenes bearing long n-alkyl chains: synthesis and application in bulk-heterojunction solar cells

    Science.gov (United States)

    Romanova, Irina P; Izdelieva, Inessa A; Trukhanov, Vasily A; Shaikhutdinova, Gulnara R; Yakhvarov, Dmitry G; Latypov, Shamil K; Mironov, Vladimir F; Dyakov, Vladimir A; Golovnin, Ilya V; Paraschuk, Dmitry Yu; Sinyashin, Oleg G

    2014-01-01

    Summary An easy, high-yield and atom-economic procedure of a C60 fullerene modification using a reaction of fullerene C60 with N-alkylisatins in the presence of tris(diethylamino)phosphine to form novel long-chain alkylindolinone-substituted methanofullerenes (AIMs) is described. Optical absorption, electrochemical properties and solubility of AIMs were studied. Poly(3-hexylthiophene-2,5-diyl) (P3HT)/AIMs solar cells were fabricated and the effect of the AIM alkyl chain length and the P3HT:AIM ratio on the solar cell performance was studied. The power conversion efficiencies of about 2% were measured in the P3HT/AIM devices with 1:0.4 P3HT:AIM weight ratio for the AIMs with hexadecyl and dodecyl substituents. From the optical and AFM data, we suggested that the AIMs, in contrast to [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), do not disturb the P3HT crystalline domains. Moreover, the more soluble AIMs do not show a better miscibility with the P3HT crystalline phase. PMID:24991262

  8. Solution-processed crystalline silicon double-heterojunction solar cells

    Science.gov (United States)

    Devkota, Ramesh; Liu, Qiming; Ohki, Tatsuya; Hossain, Jaker; Ueno, Keiji; Shirai, Hajime

    2016-02-01

    Crystalline silicon double-heterojunction solar cells were fabricated using Si/organic and Si/Cs2CO3 heterojunctions. The front heterojunction is formed by spin-coating conductive polymer poly(3,4-ethyenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on n-type Czochralski (CZ) (100) silicon, which separates the photogenerated carriers and blocks the electron dark current while allowing the photocurrent to pass through. The rear heterojunction, formed by spin-coating Cs2CO3 and polyethylenimine (PEI) dissolved in 2-ethoxyethanol and Al metal evaporation, functions as a back surface field that reduces the hole dark current while allowing the electron photocurrent to pass through. The double-heterojunction device showed a power conversion efficiency of 12.7% under AM1.5G simulated solar light exposure.

  9. Nanotomography of organic heterojunction solar cells

    International Nuclear Information System (INIS)

    The morphology of organic heterojunction solar cells based on blends of P3HT and PCBM is an important factor determining the power conversion efficiency. For a good charge carrier generation the interface between the two components should be as large as possible. Furthermore, bicontinuous networks of both components are required for an efficient charge carrier extraction. We investigate the three-dimensional structure of blends of P3HT and PCBM with Nanotomography based on scanning force microscopy (SPM). The specimen is ablated layer by layer using plasma etching and imaged with tapping mode SPM after each etching step. From the resulting series of images the three-dimensional structure is reconstructed. We will present first volume images of P3HT:PCBM blends and discuss the structure of the interface between donor and acceptor components in view of the charge generation efficiency.

  10. Enhanced Power Conversion Efficiency of P3HT : PC71BM Bulk Heterojunction Polymer Solar Cells by Doping a High-Mobility Small Organic Molecule

    Directory of Open Access Journals (Sweden)

    Hanyu Wang

    2015-01-01

    Full Text Available The effect of molecular doping with TIPS-pentacene on the photovoltaic performance of polymer solar cells (PSCs with a structure of ITO/ZnO/poly(3-hexylthiophene-2,5-diyl (P3HT : [6,6]-phenyl C71-butyric acid methyl ester (PC71BM : TIPS-pentacene/MoOx/Ag was systematically investigated by adjusting TIPS-pentacene doping ratios ranged from 0.3 to 1.2 wt%. The device with 0.6 wt% TIPS-pentacene exhibited the enhanced short-circuit current and fill factor by 1.23 mA/cm2 and 7.8%, respectively, resulting in a maximum power conversion efficiency of 4.13%, which is one-third higher than that of the undoped one. The photovoltaic performance improvement was mainly due to the balanced charge carrier mobility, enhanced crystallinity, and matched cascade energy level alignment in TIPS-pentacene doped active layer, resulting in the efficient charge separation, transport, and collection.

  11. Molecular Intercalation and Cohesion of Organic Bulk Heterojunction Photovoltaic Devices

    KAUST Repository

    Bruner, Christopher

    2013-01-17

    The phase separated bulk heterojunction (BHJ) layer in BHJ polymer:fullerene organic photovoltaic devices (OPV) are mechanically weak with low values of cohesion. Improved cohesion is important for OPV device thermomechanical reliability. BHJ devices are investigated and how fullerene intercalation within the active layer affects cohesive properties in the BHJ is shown. The intercalation of fullerenes between the side chains of the polymers poly(3,3″′-didocecyl quaterthiophene) (PQT-12) and poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT) is shown to enhance BHJ layer cohesion. Cohesion values range from ≈1 to 5 J m -2, depending on the polymer:fullerene blend, processing conditions, and composition. Devices with non-intercalated BHJ layers are found to have significantly reduced values of cohesion. The resulting device power conversion efficiencies (PCE) are also investigated and correlated with the device cohesion. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Acceptor blending ratio dependence of bulk heterojunction organic photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Haebong; Im, Chan; An, Jongdeok; Lee, Sunae; Park, Hoon [Konkuk University, Seoul (Korea, Republic of)

    2014-03-15

    Bulk heterojunction (BHJ) organic photovoltaic (OPV) devices are generally composed of a blend film of a π-conjugated polymeric electron donor and a C{sub 60} derivative electron acceptor intercalated between an anode and a cathode, typical of a two-dimensional device structure. Often, a regioregular poly(3-hexylthiophene) (rr-P3HT) and indene-C{sub 60} bisadduct (ICBA) blend film is used as the BHJ active layer instead of the conventional P3HT and phenyl-C{sub 61}-butyric acid methyl ester (PCBM) blend film due to the ICBA device's higher power conversion efficiency (PCE), which is correlated with its higher open-circuit voltage (V{sub OC} ). To determine the quantitative influences of those electron acceptors in the BHJ OPV devices, we prepared various devices of acceptors, either PCBM or ICBA, with a wide range of blending ratios (from 0 to 100%) for estimating their typical optoelectronic properties, e.g., UV-visible absorption spectra, photoluminescence intensity, surface morphology, and photovoltaic device parameters. Obtained data were compared to each other and were analyzed as a function of their acceptor blending ratio.

  13. A Cost Roadmap for Silicon Heterojunction Solar Cells

    NARCIS (Netherlands)

    Louwen, A.; van Sark, W.G.J.H.M.; Schropp, Ruud; Faaij, A.

    2016-01-01

    Research and development of silicon heterojunction (SHJ) solar cells has seen a marked increase since the recent expiry of core patents describing SHJ technology. SHJ solar cells are expected to offer various cost benefits compared to conventional crystalline silicon solar cells. This paper analyses

  14. Characterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phases

    KAUST Repository

    Sweetnam, Sean

    2014-10-08

    Theoretical and experimental studies suggest that energetic offsets between the charge transport energy levels in different morphological phases of polymer:fullerene bulk heterojunctions may improve charge separation and reduce recombination in polymer solar cells (PSCs). In this work, we use cyclic voltammetry, UV-vis absorption, and ultraviolet photoelectron spectroscopy to characterize hole energy levels in the polymer phases of polymer:fullerene bulk heterojunctions. We observe an energetic offset of up to 150 meV between amorphous and crystalline polymer due to bandgap widening associated primarily with changes in polymer conjugation length. We also observe an energetic offset of up to 350 meV associated with polymer:fullerene intermolecular interactions. The first effect has been widely observed, but the second effect is not always considered despite being larger in magnitude for some systems. These energy level shifts may play a major role in PSC performance and must be thoroughly characterized for a complete understanding of PSC function.

  15. 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. PMID:27228558

  16. Bulk heterojunction organic photovoltaic based on polythiophene-polyelectrolyte carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Reyes, M. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Lopez-Sandoval, R. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi 78216 (Mexico); Liu, J.; Carroll, D.L. [Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, NC (United States)

    2007-09-22

    It is shown that carbon nanotubes can be used to enhance carrier mobility for efficient removal of the charges in thin film polymer-conjugated/fullerene photovoltaic devices. The fabricated photovoltaic devices consist of poly(3-octylthiophene) (P3OT) polymer blended with undoped multiwalled carbon nanotubes (MWNTs) and carbon nanotubes doped with nitrogen (CNx-MWNTs). Nanophase formation and dispersion problems associated with the use of carbon nanotubes in polymer devices were addressed through the generation of functional groups and electrostatic attaching of the polyelectrolyte poly(dimethyldiallylamine) chloride (PDDA) in both MWNTs and CNx-MWNT systems. The resultant nanophase was highly dispersed allowing for excellent bulk heterojunction formation. Our results indicate that CNx-MWNTs enhance the efficiency of P3OT solar cells in comparison with MWNTs. (author)

  17. Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

    KAUST Repository

    Verploegen, Eric

    2012-10-23

    Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

  18. Carrier transport and charge transfer properties in coumarin-doped bulk-heterojunction materials

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T.; Maeda, T.; Yamashita, K. [Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Yanagi, H. [Graduate School of Materials Science, Nara Institute of Science and Technology, Nara 630-0192 (Japan)

    2012-12-15

    We have investigated photovoltaic properties of organic solar cells using polymer-fullerene bulk-heterojunction films doped with coumarin dyes. Whereas the coumarin molecules used in this study had similar absorption bands, evident difference was observed in the open-circuit voltage as well as in the short-circuit current. In particular, the doping of coumarin 307 was found to cause a distinct enhancement in the open-circuit voltage. On the other hand, the doping of coumarin 30 gave a serious degradation in the device performance. These results were strongly associated with calculated molecular energies of the doped dyes, especially with the highest occupied molecular orbital energy. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Efficiency Enhancement in Bulk Heterojunction Polymer Photovoltaic Cells Using ZrTiO4/Bi2O3 Metal-Oxide Nanocomposites

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Neppolian, B.; Shim, Hee-Sang;

    2010-01-01

    We report the effect of metal-oxide nanocomposites on the performance of bulk heterojunction polymer solar cells. A photoactive layer composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was blended with a newly developed ZrTiO4/Bi2O3 (BITZ) metal-oxide ...

  20. Insights into the nanoscale lateral and vertical phase separation in organic bulk heterojunctions via scanning probe microscopy

    Science.gov (United States)

    Chintala, R.; Tait, J. G.; Eyben, P.; Voroshazi, E.; Surana, S.; Fleischmann, C.; Conard, T.; Vandervorst, W.

    2016-02-01

    Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar+2000 gas cluster ion beam and scanning probe microscopy is used to examine the lateral and vertical phase separation within regio-regular poly(3-hexylthiophene)(P3HT):phenyl-C60-butyric acid methyl ester (PCBM) bulk heterojunction. While the Ar+2000 gas cluster ion beam is used as a sputter tool to expose the underneath layers, scanning probe microscopy techniques are used to obtain two-dimensional (2D) electrical maps (with sub-2 nm lateral resolution). The electrical mapping is decoded to chemical composition, essentially producing lateral and vertical maps of phase separation. Thermal stress causes large PCBM-rich hillocks to form, and consequently affecting the balance of P3HT:PCBM heterojunctions, hence a negative impact on the efficiency of the solar cell. We further developed a method to analyze the efficiency of exciton dissociation based on the current maps and a loss of 20% in efficiency is observed for thermally degraded samples compared to fresh un-annealed samples.Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar+2000 gas cluster ion beam and scanning probe microscopy is used to examine the

  1. Device simulation of cuprous oxide heterojunction solar cells

    Science.gov (United States)

    Takiguchi, Yuki; Miyajima, Shinsuke

    2015-11-01

    We developed a device simulation model of cuprous oxide (Cu2O)-based heterojunction solar cells. The developed model well reproduces the reported experimental current density-voltage characteristics and the external quantum efficiency results. By using the model, we explored structures for high-efficiency Cu2O-based heterojunction solar cells. It was found that the electron affinity of the buffer layer between transparent conducting oxide and Cu2O significantly affects solar cell performance. Surface recombination on the rear side of the device can be suppressed by employing a highly doped back surface layer. Our device simulation demonstrates a conversion efficiency of 16% without any optical confinement structure.

  2. Unusual charge transport and reduced bimolecular recombination in PDTSiTzTz:PC71BM bulk heterojunction blend

    International Nuclear Information System (INIS)

    Solar cells with bulk heterojunction active layers containing donor-acceptor copolymer PDTSiTzTz exhibit persistent high fill factors with thicknesses up to 400 nm. Transport and recombination in a blend of PDTSiTzTz and fullerene derivative PC71BM is studied using lateral organic photovoltaic structures. This material system is characterized by carrier-concentration-dependent charge carrier mobilities, a strongly reduced bimolecular recombination factor, and a negative Poole–Frenkel coefficient. The analysis provides an explanation for the relatively thickness-independent fill factor behaviour seen in solar cells using the copolymer PDTSiTzTz. Cumulative insights from this copolymer can be employed for future organic photovoltaic material development, study of existing high performance bulk heterojunciton blends, and improved solar cell design. (paper)

  3. Modelling charge transport lengths in heterojunction solar cells

    Science.gov (United States)

    Musselman, K. P.; Ievskaya, Y.; MacManus-Driscoll, J. L.

    2012-12-01

    A drift-diffusion model is used to estimate the minority carrier transport length and depletion width in heterojunction solar cells from measured external quantum efficiency (EQE) data. The model is applied to Cu2O-ZnO heterojunctions synthesized by electrodeposition and thermal oxidation, and the electron drift and diffusion lengths are estimated: Ldrift ≈ 110 nm for electrodeposited Cu2O and Ldrift ≈ 2790 nm and Ldiff ≈ 310 nm for thermally oxidized Cu2O. Better fitting of EQE data is obtained than with traditional models that neglect recombination in the depletion region.

  4. Investigation of Organic Solar Cells Based on Donor——A ccepter Heterojunction%Investigation of Organic Solar Cells Based onDonor——A ccepter Heterojunction

    Institute of Scientific and Technical Information of China (English)

    Gao Yinhao

    2008-01-01

    The single-l ayer structure and heterojunction structure organic solar cells based on copper phthalocyanine (CuPc),3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) and fullerene C60 were fabricated to study their photovoltaic (PV) properties. The PV performance of heterojunction structure solar cells was improved compared with the single layer structure cell.This is due to the introduction of donor-acceptor heterojunction that both expands the absorption range and offers efficient excit on dissociation site.In heterojunction structure solar cells,the PV performance of device with C60 as acceptor has highly improved because C60 has longer diffusion length o f excitons.

  5. Study of interdigitated back contact silicon heterojunctions solar cells by two-dimensional numerical simulations

    International Nuclear Information System (INIS)

    Silicon heterojunctions (SHJ) using thin layers of hydrogenated amorphous silicon (a-Si:H) deposited at low temperature on a crystalline silicon (c-Si) substrate are good candidates for high efficiency solar cells. In spite of achieving more than 22% efficiencies, the standard double HJ solar cells are limited by optical absorption and reflection at the front surface. Because it could help to overcome those limitations, the potential use of interdigitated back contact silicon heterojunctions (IBC-SHJ) structure for solar cells needs to be studied. To achieve realistic IBC-SHJ modelling, we use ATLAS 2-D device simulation software that allows accurate bulk and interface defects modelling. We here focus on IBC-SHJ structure on p-type c-Si simulations varying the values of the following parameters: bulk lifetime, surface recombination velocity at both front and back surfaces, bulk thickness, density of defects at the a-Si:H/c-Si interface. The influence of these parameters has been tested by generating the current-voltage (I-V) and spectral response curves. Results indicate that the key parameters to achieve high efficiency are a high crystalline substrate quality, low surface recombination velocity especially at the front surface, and a low recombining a-Si:H/c-Si interface. The simulations show that efficiencies up to 24% can be achieved with textured IBC-SHJ solar cells.

  6. [70] FULLERENE-BASED EFFICIENT BULK HETEROJUNCTION SOLAR CELLS%以C70衍生物为电子受体的高效聚合物固体薄膜太阳能电池

    Institute of Scientific and Technical Information of China (English)

    王藜; 徐苗; 应磊; 刘烽; 曹镛

    2008-01-01

    以PC[70]BM(phenyl C71-butyric acid methyl ester)取代PC[60]BM(phenyl C61-butyric acid methyl ester)作为电子受体材料,以MEH-PPV(poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene])为电子给体材料,制成了本体异质结(bulk heterojunction,BHJ)聚合物太阳能电池.MEH-PPV/PC[70]BM器件在AM1.5G(80 mW/cm2)模拟太阳光的光照条件下得到了3.42%的能量转换效率,短路电流值达到了6.07 mA/cm2,开路电压0.85 V,填充因子为53%.通过紫外可见吸收光谱和外量子效率的研究,发现PC[70]BM作为电子受体,对扩大光谱的吸收范围和增加活性层的吸收系数有明显的作用.同时比较了不同溶剂对该体系器件性能的影响.通过原子力显微镜(AFM)、光暗导I-V曲线等研究,分析了1,2-二氯苯有利于给体相和受体相的微相分离和载流子的传输的原因.

  7. Monolayer MoS2 heterojunction solar cells

    KAUST Repository

    Tsai, Menglin

    2014-08-26

    We realized photovoltaic operation in large-scale MoS2 monolayers by the formation of a type-II heterojunction with p-Si. The MoS 2 monolayer introduces a built-in electric field near the interface between MoS2 and p-Si to help photogenerated carrier separation. Such a heterojunction photovoltaic device achieves a power conversion efficiency of 5.23%, which is the highest efficiency among all monolayer transition-metal dichalcogenide-based solar cells. The demonstrated results of monolayer MoS 2/Si-based solar cells hold the promise for integration of 2D materials with commercially available Si-based electronics in highly efficient devices. © 2014 American Chemical Society.

  8. Squaraine Planar-Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Bin Fan

    2009-01-01

    derivatives with extraordinarily high extinction coefficients are used as electron donors in bilayer heterojunctions with fullerene C60 as electron acceptor. Due to the very strong squaraine absorption band in the red spectral domain, antibatic behavior due to light filtering is observed in the photocurrent spectrum for film thicknesses of 35 nm to 40 nm. At reduced film thicknesses of 20 nm, this filtering effect at maximum absorption can be alleviated and power conversion efficiencies under simulated AM 1.5 full sun irradiation of 0.59% and 1.01% are obtained for the two squaraine derivatives, respectively. The photovoltaic properties of these cells are investigated with respect to electrode materials and chemical doping.

  9. Characterization of silicon heterojunctions for solar cells

    Directory of Open Access Journals (Sweden)

    Ankudinov Alexander

    2011-01-01

    Full Text Available Abstract Conductive-probe atomic force microscopy (CP-AFM measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H and n-type crystalline silicon (c-Si as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p a-Si:H/(n c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n a-Si:H/(p c-Si heterojunctions. These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

  10. Universal formation of compositionally graded bulk heterojunction for efficiency enhancement in organic photovoltaics.

    Science.gov (United States)

    Xiao, Zhengguo; Yuan, Yongbo; Yang, Bin; VanDerslice, Jeremy; Chen, Jihua; Dyck, Ondrej; Duscher, Gerd; Huang, Jinsong

    2014-05-21

    A universal method is reported to form graded bulk heterojunction (BHJ) organic photovoltaic devices (OPVs) by a simple solvent-fluxing process. Donors are enriched at the anode and acceptors are enriched at cathode side, matching the gradient electron and hole current across the film. Efficiency enhancements by 15-50% are achieved for all BHJ systems tested compared with the optimized regular BHJ OPVs.

  11. Carrier injection dynamics in heterojunction solar cells with bipolar molecule

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yosuke; Yonezawa, Kouhei [Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8571 (Japan); Yasuda, Takeshi, E-mail: YASUDA.Takeshi@nims.go.jp, E-mail: moritomo.yutaka.gf@u.tsukuba.ac.jp [Photovoltaic Materials Unit, National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Moritomo, Yutaka, E-mail: YASUDA.Takeshi@nims.go.jp, E-mail: moritomo.yutaka.gf@u.tsukuba.ac.jp [Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba 305-8571 (Japan); Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba, Tsukuba 305-8571 (Japan)

    2015-03-23

    A boron subphthalocyanine chloride (SubPc) is a bipolar molecule and is used in hetero-junction organic solar cells. Here, we investigated the carrier injection dynamics from the donor α-sexithiophene (6T) or acceptor C{sub 60} layers to the bipolar SubPc layer by means of the femtosecond time-resolved spectroscopy. We observed gradual increase of the SubPc{sup –} (SubPc{sup +}) species within ≈300 ps. The increases are interpreted in terms of the exciton diffusion within the 6T (C{sub 60}) layer and subsequent electron (hole) injection at the interface. In 6T/SubPc heterojunction, the electron injection is observed even at 80 K. The robust electron injection is ascribed to the efficient charge separation within the 6T layer under photo exciation at 400 nm.

  12. Formation of P3KHT:PCBM bulk-heterojunction using orthogonal solvents by ultrasonic spray method

    Science.gov (United States)

    Mahajan, Mrunal S.; Lonkar, Ganesh S.; Ghosh, Sanjay S.; Patil, Mahendra B.; Dalal, Dipak S.; Sali, Jaydeep V.

    2015-07-01

    Bulk-heterojunction (BHJ) morphologies with pure domains and sharp interfaces can lead to a more pronounced photovoltaic performance in organic solar cells. In this paper we report the formation of bulk-heterojunction of P3KHT (poly [3-(sodium-6 hexanoate) thiophene-2, 5-diyl]) and PCBM (phenyl-C61-butyric acid methyl ester) using orthogonal solvents by the ultrasonic spray method, which can lead to pure phases and sharp interfaces. P3KHT and PCBM are soluble in water and chlorobenzene respectively, which are orthogonal solvents. The modelling and simulation of the ultrasonic spray method is reported, and shows the possibility of formation of interconnecting phases of the two components in P3KHT:PCBM BHJ, formed using orthogonal solvents, if specific process parameters are chosen. The modelling and simulation also presents a way to determine optimum parameter space in an intermittent spray deposition method using orthogonal solvents. P3KHT:PCBM BHJ has been prepared using three different approaches. Significant photoluminescence quenching, suggesting efficient excitons separation before recombination has been observed in BHJ prepared by the ‘emulsion of solutions’ method. The study of the optical properties of P3KHT:PCBM BHJ suggests that the BHJ may contain bilayer type structures embedded in the BHJ morphology, which is further confirmed by complementary experiments. This new approach to preparing BHJ with pure phase domains and sharp donor/acceptor interfaces may find applications in optoelectronic devices such as organic thin-film transistors, photodetectors, organic light emitting diodes and organic solar cells.

  13. Formation of P3KHT:PCBM bulk-heterojunction using orthogonal solvents by ultrasonic spray method

    International Nuclear Information System (INIS)

    Bulk-heterojunction (BHJ) morphologies with pure domains and sharp interfaces can lead to a more pronounced photovoltaic performance in organic solar cells. In this paper we report the formation of bulk-heterojunction of P3KHT (poly [3-(sodium-6 hexanoate) thiophene-2, 5-diyl]) and PCBM (phenyl-C61-butyric acid methyl ester) using orthogonal solvents by the ultrasonic spray method, which can lead to pure phases and sharp interfaces. P3KHT and PCBM are soluble in water and chlorobenzene respectively, which are orthogonal solvents. The modelling and simulation of the ultrasonic spray method is reported, and shows the possibility of formation of interconnecting phases of the two components in P3KHT:PCBM BHJ, formed using orthogonal solvents, if specific process parameters are chosen. The modelling and simulation also presents a way to determine optimum parameter space in an intermittent spray deposition method using orthogonal solvents. P3KHT:PCBM BHJ has been prepared using three different approaches. Significant photoluminescence quenching, suggesting efficient excitons separation before recombination has been observed in BHJ prepared by the ‘emulsion of solutions’ method. The study of the optical properties of P3KHT:PCBM BHJ suggests that the BHJ may contain bilayer type structures embedded in the BHJ morphology, which is further confirmed by complementary experiments. This new approach to preparing BHJ with pure phase domains and sharp donor/acceptor interfaces may find applications in optoelectronic devices such as organic thin-film transistors, photodetectors, organic light emitting diodes and organic solar cells. (paper)

  14. Morphology-dependent trap formation in bulk heterojunction photodiodes.

    Science.gov (United States)

    Shao, Guozheng; Rayermann, Glennis E; Smith, Eric M; Ginger, David S

    2013-04-25

    We show that local structural variation affects the rate of aging in nanostructured polymer solar cells by comparing time-resolved electrostatic force microscopy (trEFM) and conventional device measurements on model polymer blends. Specifically, we study photovoltaic devices made from 1:1 blends of the polyfluorene copolymers poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylene-diamine) (PFB) and poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT). We photooxidize these films in situ using 365, 405, and 455 nm illumination under ambient conditions, with the wavelengths chosen to preferentially excite the different components. During photooxidation, we observe a faster loss of photocurrent generation from F8BT-rich domains, leaving the PFB-rich phases to show higher photoresponse even at wavelengths absorbed predominantly by F8BT. We propose that this effect is due to the more rapid degradation of PFB hole-transport pathways in the F8BT-rich regions, resulting in a loss of percolation pathways for hole transport in the F8BT-rich phase. PMID:23256510

  15. Performance of spray deposited poly [N-9 Double-Prime -hepta-decanyl-2,7-carbazole-alt-5,5-(4 Prime ,7 Prime -di-2-thienyl-2 Prime ,1 Prime , 3 Prime -benzothiadiazole)]/[6,6]-phenyl-C61-butyric acid methyl ester blend active layer based bulk heterojunction organic solar cell devices

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Leona [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan); Babu, R. Ramesh [Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli-620 024, Tamil Nadu (India); Kannappan, Santhakumar; Kojima, Kenzo; Mizutani, Teruyoshi [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan); Ochiai, Shizuyasu, E-mail: ochiai@aitech.ac.jp [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan)

    2012-01-31

    Bulk heterojunction organic solar cell devices were fabricated using the spray deposited poly [N-9 Double-Prime -hepta-decanyl-2,7-carbazole-alt-5,5-(4 Prime ,7 Prime -di-2-thienyl-2 Prime ,1 Prime , 3 Prime -benzothiadiazole)]/[6,6]-phenyl-C61-butyric acid methyl ester blend active layer. The spray coating parameters such as spraying time, substrate-nozzle distance for the deposition of active layers were analyzed. Optical absorption of the active layers was analyzed using UV-visible spectral studies in the wavelength range from 300 to 800 nm. The surface morphology of the active layers deposited with different parameters was examined using atomic force microscopy. Surface morphology of the active layers deposited with the substrate-nozzle distance of 20 cm and for 20 s shows smooth morphology with peak-valley value of 4 nm. The devices fabricated using the selected active layer show overall power conversion efficiency of 1.08%. - Graphical abstract: Current-voltage (J-V) characteristics of spray deposited PCDTBT:PC{sub 61}BM active layer based solar cell device under illumination of AM 1.5 G, 100 mW/cm{sup 2}. Highlights: Black-Right-Pointing-Pointer Organic solar cells were fabricated using a spray deposited PCDTBT:PC61BM active layer. Black-Right-Pointing-Pointer The active layers deposited with spray conditions show flat morphology. Black-Right-Pointing-Pointer Using the selected active layers power conversion efficiency of 1.08% is obtained.

  16. Electrical and optical design and characterisation of regioregular poly(3-hexylthiophene-2,5diyl)/fullerene-based heterojunction polymer solar cells

    NARCIS (Netherlands)

    Chirvase, D; Chiguvare, Z; Knipper, A; Parisi, J; Dyakonov, [No Value; Hummelen, JC; Knipper, M.

    2003-01-01

    Electrical and optical properties of poly(3-hexylthiophene-2,5diyl) (P3HT-2,5diyl) used as the main component in a bulk heterojunction polymer/fullerene solar cell were investigated. The HOMO level of the polymer was estimated at about 4.7-5.1 eV, from the observed space charge limited current (SCLC

  17. Photoanodic Hybrid Semiconductor–Molecular Heterojunction for Solar Water Oxidation

    KAUST Repository

    Joya, Khurram Saleem

    2015-06-29

    Inorganic photo-responsive semiconducting materials have been employed in photoelectrochemical(PEC) water oxidation devicesin pursuit of solar to fuel conversion.[1]The reaction kinetics in semiconductors is limited by poor contact at the interfaces, and charge transfer is impeded by surface defects and the grain boundaries.[2]It has shown that successful surface functionalization of the photo-responsive semiconducting materials with co-catalysts can maximize the charge separation, hole delivery and its effective consumption, and enhances the efficiency and performane of the PEC based water oxidation assembly.[3]We present here unique modification of photoanodic hematite (α-Fe2O3) and bismuth vanadate (BiVO4) with molecular co-catalysts for enhanced photoelectrochemical water oxidation (Figure 1). These hybrid inorganic–organometallic heterojunctions manifest impressive cathodic shifts in the onset potentials, and the photocurrent densities have been enhanced by > 90% at all potentials relative to uncatalyzed α-Fe2O3 or BiVO4, and other catalyst-semiconductor based heterojunctions.This is a novel development in the solar to fuel conversion field, and is crucially important for designing a tandem device where light interfere very little with the catalyst layer on top of semiconducting light absorber.

  18. High efficiency silicon nanohole/organic heterojunction hybrid solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Lei [Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Singapore Institute of Manufacturing Technology, A-STAR (Agency for Science, Technology and Research), 71 Nanyang Drive, Singapore 638075 (Singapore); Wang, Xincai; Zheng, Hongyu [Singapore Institute of Manufacturing Technology, A-STAR (Agency for Science, Technology and Research), 71 Nanyang Drive, Singapore 638075 (Singapore); He, Lining; Wang, Hao; Rusli, E-mail: yu.hy@sustc.edu.cn, E-mail: erusli@ntu.edu.sg [Novitas, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yu, Hongyu, E-mail: yu.hy@sustc.edu.cn, E-mail: erusli@ntu.edu.sg [South University of Science and Technology of China, Shenzhen (China)

    2014-02-03

    High efficiency hybrid solar cells are fabricated based on silicon with a nanohole (SiNH) structure and poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The SiNH structure is fabricated using electroless chemical etching with silver catalyst, and the heterojunction is formed by spin coating of PEDOT on the SiNH. The hybrid cells are optimized by varying the hole depth, and a maximum power conversion efficiency of 8.3% is achieved with a hole depth of 1 μm. The SiNH hybrid solar cell exhibits a strong antireflection and light trapping property attributed to the sub-wavelength dimension of the SiNH structure.

  19. Dibenzo[f,h]thieno[3,4-b] quinoxaline-fullerene heterojunction bilayer solar cells with complementary spectrum coverage

    Energy Technology Data Exchange (ETDEWEB)

    Kekuda, Dhananjaya [Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei (China); Huang, Jen-Shien [Department of Chemical Engineering, National Taiwan University (China); Velusamy, Marappan; Lin, Jiann T. [Institute of Chemistry, Academia Sinica, Nankang, Taipei (China); Chu, Chih-Wei [Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei (China); Department of Photonics, National Chio-Tung University, Hsinchu 30013 (China)

    2010-10-15

    In the present article, potential of a bilayer organic solar cell has been investigated. We utilize newly synthesized small molecules, namely dibenzo[f,h]thieno[3,4-b]quinoxaline as electron donors for solar cells in heterojunction bilayer configuration. These small molecules with a narrow absorption band in the range 400-450 nm provide a complementary spectrum for the fullerene C{sub 70}, thereby leading to an overall power conversion efficiency of 2.6{+-}0.2% under 100 mW/cm{sup 2} incident radiation. Thermal annealing seems to impact the charge separation at the donor-acceptor interface, which eventually affects device performance. This work demonstrates that carefully optimized bilayer devices are comparable to the bulk heterojunction counterparts. (author)

  20. Surface recombination analysis in silicon-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, R.; Gandia, J.J.; Carabe, J.; Gonzalez, N.; Torres, I. [CIEMAT, Madrid (Spain); Munoz, D.; Voz, C. [Universitat Politecnica de Catalunya, Barcelona (Spain)

    2010-02-15

    The origin of this work is the understanding of the correlation observed between efficiency and emitter-deposition temperature in single silicon-heterojunction solar cells prepared by depositing an n-doped hydrogenated-amorphous-silicon thin film onto a p-type crystalline-silicon wafer. In order to interpret these results, surface-recombination velocities have been determined by two methods, i.e. by fitting the current-voltage characteristics to a theoretical model and by means of the Quasi-Steady-State Photoconductance Technique (QSSPC). In addition, effective diffusion lengths have been estimated from internal quantum efficiencies. The analysis of these data has led to conclude that the performance of the cells studied is limited by back-surface recombination rather than by front-heterojunction quality. A 12%-efficient cell has been prepared by combining optimum emitter-deposition conditions with back-surface-field (BSF) formation by vacuum annealing of the back aluminium contact. This result has been achieved without using any transparent conductive oxide. (author)

  1. Fabrication of CdTe/Si heterojunction solar cell

    Science.gov (United States)

    Bera, Swades Ranjan; Saha, Satyajit

    2016-01-01

    A simple cost effective method is preferred to grow nanoparticles of CdTe. Nanoparticles of CdTe are grown by simple chemical reduction route using EDA as capping agent and Sodium Borohydride as reducing agent. The grown nanoparticles are characterized using transmission electron microscopy (TEM), X-ray diffraction, optical absorption, and photoluminescence study. From optical absorption study, the band-gap was found to be 2.46 eV. From TEM study, the average particle size was found to be within 8-12 nm which confirms the formation of CdTe nanoparticles. Pl spectra indicate the luminescence from surface states at 2.01 eV, which is less compared to the increased band-gap of 2.46 eV. The grown nanoparticles are used to fabricate a heterojunction of CdTe on P-Si by a spin coating technique for solar cell fabrication in a cost effective way. I-V characteristics of the grown heterojunction in dark as well as under light are measured. Efficiency and fill-factor of the device are estimated.

  2. The role of the hole-extraction layer in determining the operational stability of a polycarbazole:fullerene bulk-heterojunction photovoltaic device

    Energy Technology Data Exchange (ETDEWEB)

    Bovill, E.; Scarratt, N.; Griffin, J.; Buckley, A. R.; Lidzey, D. G., E-mail: d.g.lidzey@sheffield.ac.uk [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Yi, H.; Iraqi, A. [Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom); Kingsley, J. W. [Ossila Ltd., Kroto Innovation Centre, Broad Lane, Sheffield S3 7HQ (United Kingdom)

    2015-02-16

    We have made a comparative study of the relative operational stability of bulk-heterojunction organic photovoltaic (OPV) devices utilising different hole transport layers (HTLs). OPV devices were fabricated based on a blend of the polymer PCDTBT with the fullerene PC{sub 70}BM, and incorporated the different HTL materials PEDOT:PSS, MoO{sub x} and V{sub 2}O{sub 5}. Following 620 h of irradiation by light from a solar simulator, we find that devices using the PEDOT:PSS HTL retained the highest efficiency, having a projected T{sub 80} lifetime of 14 500 h.

  3. InGaP Heterojunction Barrier Solar Cells

    Science.gov (United States)

    Welser, Roger E. (Inventor)

    2014-01-01

    A new solar cell structure called a heterojunction barrier solar cell is described. As with previously reported quantum-well and quantum-dot solar cell structures, a layer of narrow band-gap material, such as GaAs or indium-rich InGaP, is inserted into the depletion region of a wide band-gap PN junction. Rather than being thin, however, the layer of narrow band-gap material is about 400-430 nm wide and forms a single, ultrawide well in the depletion region. Thin (e.g., 20-50 nm), wide band-gap InGaP barrier layers in the depletion region reduce the diode dark current. Engineering the electric field and barrier profile of the absorber layer, barrier layer, and p-type layer of the PN junction maximizes photogenerated carrier escape. This new twist on nanostructured solar cell design allows the separate optimization of current and voltage to maximize conversion efficiency.

  4. Effect of perylenetetracarboxylic dianhydride layer as a hole blocking layer on photovoltaic performance of poly-vinylcarbazole: C{sub 60} bulk heterojunction thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Nomura, Katsunori; Suzuki, Atsushi; Kikuchi, Kenji

    2012-01-31

    Thin film solar cells with a structure of poly(9-vinylcarbazole) and C{sub 60} bulk heterojunction were fabricated and characterized. The effects of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) as a hole blocking layer for the organic solar cells between active layer and metal layer were also investigated, and the optimized cell structures with PTCDA improved the short-circuit current density and fill factor up to twice values, which resulted in an increase of the conversion efficiency. Microstructure analysis was carried out by using X-ray diffraction and transmission electron microscopy, which indicated the bulk nanocomposite structure Energy levels of the molecules were calculated, and the interfacial structure was discussed based on the experimental and calculated results.

  5. Investigation of metal oxide/cuprous oxide heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Herion, J.; Neikisch, E.A.; Scharl, G.

    1980-12-01

    ZnO/Cu/sub 2/O heterojunction solar cells can be prepared by means of rf sputter deposition of In-doped ZnO layers on Cu/sub 2/O. The temperature at which ZnO is deposited is found to be of crucial importance for the photovoltaic performance of the cells. Maxima of the open-circuit voltage, the short-circuit current, and the dark resistance are observed for deposition temperatures between 230 and 240/sup 0/C. Auger sputter profiles show an oxygen depletion zone at the ZnO/Cu/sub 2/O interface which can be attributed to a very thin copper layer. The oxygen depletion and, correspondingly, the copper enrichment are apparently correlated with the photovoltaic effects. A relatively small copper enrichment has also been observed in CuO/Cu/sub 2/O cells. However, the nature of copper enrichment seems to be different in both types of cells.

  6. Photoconductance of Bulk Heterojunctions with Tunable Nanomorphology Consisting of P3HT and Naphtalene Diimide Siloxane Oligomers

    NARCIS (Netherlands)

    Grzegorczyk, W.J.; Ganesan, P.; Savenije, T.J.; Bavel, van S.; Loos, J.; Sudhölter, E.J.R.; Siebbeles, L.D.A.; Zuilhof, H.

    2009-01-01

    The relation between the morphology, optical, and photoconductive properties of thin-film bulk heterojunctions of poly(3-hexylthiophene) (P3HT) with a series of electron-accepting siloxanes with a different number (x = 2, 4, 5) of pendant naphthalene diimide (NDIS) moieties is reported. All NDIS sil

  7. The Improvement of Bulk-Heterojunction Order in Polymer Photovoltaic Device

    Institute of Scientific and Technical Information of China (English)

    YUAN Dan; CHEN Zhi-jian; XIAOLi-xin; MULi-ping; QU Bo; GONG Qi-huang

    2011-01-01

    The blend morphology and vertical arrangement are critical to the performance of organic bulk-heterojunction photovoltaic devices.In the present paper,the authors proposed a new annealing method that controis the blend morphology and vertical arrangement of two materials by means of simultaneously applying external electrical field and violet irradiation on the active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) during annealing process.By using this annealing method,the power conversion efficiency increased by 36%,which was caused by vertical phased-separated blend of crystalline P3HT and PCBM and better charge extraction of electrodes.X-ray photoelectron spectroscopy (XPS) was measured to prove more fullerene derivatives at the organic/cathode interfaces by using this annealing method.The X-ray diffraction (XRD) analysis and UV-Vis absorption spectrum analysis also revealed more ordered polymer crystallization.

  8. Femtosecond spectroscopic studies of photoinduced electron transfer in MDMO-PPV:ZnO hybrid bulk heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Cecchetto, E.; De Cola, L. [Institute of Physics, University of Muenster, Mendelstrasse 7, 48149 Muenster (Germany); Slooff, H. [ECN Solar Energy, P.O. Box 1, 1755 ZG Petten (Netherlands); Zhang, H. [Van ' t Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS Amsterdam (Netherlands)

    2007-01-15

    The photophysics of charge carriers (polaron) in MDMO-PPV:ZnO hybrid bulk heterojunction is studied at 80 K by femtosecond transient absorption spectroscopy. A short-lived positive polaron is observed in the blend phase in MDMO-PPV:ZnO blend films with a weight ratio of 1:1 and 1:2. Further increase of ZnO weight ratio results in a significant quenching of the polaron absorption. The results are discussed in the concept that both pristine polymer and MDMO-PPV:ZnO blend phases coexist in the blend films. It is concluded that a polaron is photogenerated within the excitation laser pulse (<100 fs) and electron transfer efficiency is highest in blend films 1:1 and 1:2. Lack of the interfacial area and faster back electron transfer process are discussed to be responsible for the quenching of the electron transfer efficiency in blend film 1:3.

  9. Tailor-Made Additives for Morphology Control in Molecular Bulk-Heterojunction Photovoltaics

    KAUST Repository

    Graham, Kenneth R.

    2013-01-09

    Tailor-made additives, which are molecules that share the same molecular structure as a parent molecule with only slight structural variations, have previously been demonstrated as a useful means to control crystallization dynamics in solution. For example, tailor-made additives can be added to solutions of a crystallizing parent molecule to alter the crystal growth rate, size, and shape. We apply this strategy as a means to predictably control morphology in molecular bulk-heterojunction (BHJ) photovoltaic cells. Through the use of an asymmetric oligomer substituted with a bulky triisobutylsilyl end group, the morphology of BHJ blends can be controlled resulting in a near doubling (from 1.3 to 2.2%) in power conversion efficiency. The use of tailor-made additives provides promising opportunities for controlling crystallization dynamics, and thereby film morphologies, for many organic electronic devices such as photovoltaics and field-effect transistors. © 2012 American Chemical Society.

  10. Depleted-Heterojunction Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Pattantyus-Abraham, Andras G.

    2010-06-22

    Colloidal quantum dot (CQD) photovoltaics combine low-cost solution processability with quantum size-effect tunability to match absorption with the solar spectrum. Rapid recent advances in CQD photovoltaics have led to impressive 3.6% AM1.5 solar power conversion efficiencies. Two distinct device architectures and operating mechanisms have been advanced. The first-the Schottky device-was optimized and explained in terms of a depletion region driving electron-hole pair separation on the semiconductor side of a junction between an opaque low-work-function metal and a p-type CQD film. The second-the excitonic device-employed a CQD layer atop a transparent conductive oxide (TCO) and was explained in terms of diffusive exciton transport via energy transfer followed by exciton separation at the type-II heterointerface between the CQD film and the TCO. Here we fabricate CQD photovoltaic devices on TCOs and show that our devices rely on the establishment of a depletion region for field-driven charge transport and separation, and that they also exploit the large bandgap of the TCO to improve rectification and block undesired hole extraction. The resultant depletedheterojunction solar cells provide a 5.1% AM1.5 power conversion efficiency. The devices employ infrared-bandgap size-effect-tuned PbS CQDs, enabling broadband harvesting of the solar spectrum. We report the highest opencircuit voltages observed in solid-state CQD solar cells to date, as well as fill factors approaching 60%, through the combination of efficient hole blocking (heterojunction) and very small minority carrier density (depletion) in the large-bandgap moiety. © 2010 American Chemical Society.

  11. Solution-Processed Organic Solar Cells from Dye Molecules: An Investigation of Diketopyrrolopyrrole:Vinazene Heterojunctions

    KAUST Repository

    Walker, Bright

    2012-01-25

    Although one of the most attractive aspects of organic solar cells is their low cost and ease of fabrication, the active materials incorporated into the vast majority of reported bulk heterojunction (BHJ) solar cells include a semiconducting polymer and a fullerene derivative, classes of materials which are both typically difficult and expensive to prepare. In this study, we demonstrate that effective BHJs can be fabricated from two easily synthesized dye molecules. Solar cells incorporating a diketopyrrolopyrrole (DPP)-based molecule as a donor and a dicyanoimidazole (Vinazene) acceptor function as an active layer in BHJ solar cells, producing relatively high open circuit voltages and power conversion efficiencies (PCEs) up to 1.1%. Atomic force microscope images of the films show that active layers are rough and apparently have large donor and acceptor domains on the surface, whereas photoluminescence of the blends is incompletely quenched, suggesting that higher PCEs might be obtained if the morphology could be improved to yield smaller domain sizes and a larger interfacial area between donor and acceptor phases. © 2011 American Chemical Society.

  12. Wide-bandgap epitaxial heterojunction windows for silicon solar cells

    Science.gov (United States)

    Landis, Geoffrey A.; Loferski, Joseph J.; Beaulieu, Roland; Sekula-Moise, Patricia A.; Vernon, Stanley M.

    1990-01-01

    It is shown that the efficiency of a solar cell can be improved if minority carriers are confined by use of a wide-bandgap heterojunction window. For silicon (lattice constant a = 5.43 A), nearly lattice-matched wide-bandgap materials are ZnS (a = 5.41 A) and GaP (a = 5.45 A). Isotype n-n heterojuntions of both ZnS/Si and GaP/Si were grown on silicon n-p homojunction solar cells. Successful deposition processes used were metalorganic chemical vapor deposition (MO-CVD) for GaP and ZnS, and vacuum evaporation of ZnS. Planar (100) and (111) and texture-etched - (111)-faceted - surfaces were used. A decrease in minority-carrier surface recombination compared to a bare surface was seen from increased short-wavelength spectral response, increased open-circuit voltage, and reduced dark saturation current, with no degradation of the minority carrier diffusion length.

  13. Effects of thermal treatment and depth profiling analysis of solution processed bulk-heterojunction organic photovoltaic cells.

    Science.gov (United States)

    Mbule, Pontsho S; Swart, Hendrik C; Ntwaeaborwa, Odireleng M

    2014-12-15

    We report the use of solution processed zinc oxide (ZnO) nanoparticles as a buffer layer inserted between the top metal electrode and the photo-active layer in bulk-heterojunction (BHJ) organic solar cell (OSC) devices. The photovoltaic properties were compared for devices annealed before (Device A) or after (Device B) the deposition of the Al top electrode. The post-annealing treatment was shown to improve the power conversion efficiency up to 2.93% and the fill factor (FF) up to 63% under AM1.5 (100mW/cm(2)) illumination. We performed the depth profile/interface analysis and elemental mapping using the time-of-flight secondary ion mass spectrometry (TOF-SIMS). Signals arising from (27)Al, (16)O, (12)C, (32)S, (64)Zn, (28)Si, (120)Sn and (115)In give an indication of successive deposition of Al, ZnO, P3HT:PCBM and PEDOT:PSS layers on ITO coated glass substrates. Furthermore, we discuss the surface imaging and visualize the chemical information on the surface of the devices.

  14. POSS-enhanced phase separation in air-processed P3HT:PCBM bulk heterojunction photovoltaic systems.

    Science.gov (United States)

    Wu, Qi; Bhattacharya, Mithun; Morgan, Sarah E

    2013-07-10

    Nanoparticles have been shown in some cases to improve phase separation and morphology in bulk heterojunction organic photovoltaic cells. In this study, the effect of incorporation of polyhedral oligomeric silsesquioxane (POSS) molecules of different structures in air processed poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) films and photovoltaic cells was evaluated. Morphology and composition of the nanoscalephase-separated domains were determined via conductive atomic force microscopy in conjunction with nanomechanical mapping and Raman imaging. UV-vis and fluorescence spectroscopy analysis of the films was performed at different stages of the process and with different levels of solvent vapor and thermal annealing. It was found that POSS molecules of selected structures provided enhancement in morphology control in films, translating to improvements in fill factor and power conversion efficiency of laboratory-scale OPV cells. The findings indicate the potential for further improvements in solar cell performance with specifically tailored POSS/polymer phase-separated systems.

  15. High-efficiency silicon heterojunction solar cells: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    De Wolf, S.

    2015-04-27

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on n-type wafers, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short- wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long-wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metalisation grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical transport requirements. The

  16. High-efficiency silicon heterojunction solar cells: Status and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    De Wolf, S.; Geissbuehler, J.; Loper, P.; Martin de Nicholas, S.; Seif, J.; Tomasi, A.; Ballif, C.

    2015-05-11

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on both-sides contacted n-type cells, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short-wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long- wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metallization grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical

  17. Fabrication of c-Si:H(p)/c-Si(n) Heterojunction Solar Cells with Microcrystalline Emitters

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bing-Qing; LIU Feng-Zhen; ZHANG Qun-Fang; XU Ying; ZHOU Yu-Qin; LIU Jin-Long; ZHU Mei-Fang

    2006-01-01

    The p-type microcrystalline silicon (fj,c-Si) on n-type crystalline silicon (c-Si) heterojunction solar cells is fabricated by radio-frequency plasma enhanced chemical vapour deposition (rf-PECVD). The effect of the pc-Si:H p-layers on the performance of the heterojunction solar cells is investigated. Optimum μcSi:H p-layer is obtained with hydrogen dilution ratio of 99.65%, rf-power of 0.08 W/cm2, gas phase doping ratio of 0.125%, and the p-layer thickness of 15 nm. We fabricate μc-Si:H(p)/c-Si(n) heterojunction solar cells without texturing and obtained an efficiency of 13.4%. The comparisons of the solar-cell performances using different surface passivation techniques are discussed.

  18. Magnetophotocurrent in Organic Bulk Heterojunction Photovoltaic Cells at Low Temperatures and High Magnetic Fields

    Science.gov (United States)

    Khachatryan, B.; Devir-Wolfman, A. H.; Tzabari, L.; Tessler, N.; Vardeny, Z. V.; Ehrenfreund, E.

    2016-04-01

    We study high-field (up to B ˜8.5 T ) magnetophotocurrent (MPC) related to photogenerated polaron pairs (PPs) in the temperature range T =10 - 320 K in organic bulk heterojunction photovoltaic cells. We find that in the high-field regime (B >1 T ), MPC (B ) response increases with B for temperature T >200 K but decreases with B at T <200 K . MPC (B ) response does not saturate even at the highest field studied, at all T . We attribute the observed high-field MPC (B ) response to two competing mechanisms within the PP spin states: (a) a spin-mixing mechanism caused by the difference in the donor-acceptor (or positive-negative polarons) g factors (the so-called "Δ g mechanism"), and (b) the spin polarization induced by thermal population of the PP Zeeman split levels. The nonsaturating MPC (B ) response at high fields and high temperatures indicates that there exist charge-transfer excitons (CTEs) with decay time in the subnanosecond time domain. With decreasing temperature, the CTE decay time sharply increases, thereby promoting an increase of the thermal spin-polarization contribution to the MPC (B ) response.

  19. Photovoltaic and Electroluminescence Characters in Hybrid ZnO and Conjugated Polymer Bulk Heterojunction Devices

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-Peng; QU Sheng-Chun; XU Ying; CHEN Yong-Hai; ZENG Xiang-Bo; WANG Zhi-Jie; ZHOU Hui-Ying; WANG Zhan-Guo

    2007-01-01

    We report electroluminescence in hybrid ZnO and conjugated polymer poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) bulk heterojunction photovoltaic cells. Photoluminescence quenching experimental results indicate that the ultrafast photoinduced electron transfer occurs from MDMO-PPV to ZnO under illumination. The ultrafast photoinduced electron transfer effect is induced because ZnO has an electron affinity about 1.2 eV greater than that of MDMO-PPV. Electron 'back transfer' can occur if the interfacial barrier between ZnO and MDMO-PPV can be overcome by applying a substantial electric field. Therefore, electroluminescence action due to the fact that the back transfer effect can be observed in the ZnO: MDMO-PPV devices since a forward bias is applied. The photovoltaic and electroluminescence actions in the same ZnO: MDMO-PPV device can be induced by different injection ways: photoinjection and electrical injection. The devices are expected to provide an opportunity for dual functionality devices with photovoltaic effect and electroluminescence character.

  20. Fabrication and characterization of DBM/p-Si heterojunction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M.; Kamel, M.A. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Atta, A.A. [Physics Department, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Physics Department, Faculty of Science, Taif University, Taif, 888 Taif (Saudi Arabia); Huthaily, S.Y., E-mail: s_huthaily@yahoo.com [Physics Department, Faculty of Education, Hodeidah University, Alduraihimi, 3114 Hodeidah (Yemen)

    2013-01-15

    Hybrid organic/inorganic solar cell was fabricated by depositing a thin film of p-N,N dimethylaminobenzylidenemalononitrile (DBM) onto p-Si substrate. DBM is a donor-acceptor disubstituted benzenes dye known as molecular rotors and highly polar molecular compounds. Its powder has a polycrystalline structure, while nano-crystallite rods are formed in the as-deposited film. The dark current density-voltage (J-V) characteristics of Au/DBM/p-Si/Al heterojunction device measured at different temperatures ranging from 291 to 353 K have been investigated. The operating conduction mechanisms, the series and shunt resistances, the rectification ratio, the ideality factor, the effective barrier height, and the total trap concentration were determined. The capacitance-voltage (C-V) characteristics indicated that the junction is of abrupt nature. The built-in voltage and the carrier concentration distributed through the depletion region were estimated. Under illumination, the DBM/p-Si cell showed photovoltaic properties and the photovoltaic parameters were evaluated. -- Highlights: Black-Right-Pointing-Pointer The molecular rotors DBM dye can be used to manufacture D/A solar cells. Black-Right-Pointing-Pointer Since D/A are situated in the DBM molecule, we ensure photoinduced D {yields} A electron transfer. Black-Right-Pointing-Pointer The DBM film is grown as nano-rods. Black-Right-Pointing-Pointer The most of the DBM bulk of the cell contributes to the generation of external current.

  1. Simulation and optimization of the performance of organic photovoltaic cells based on capped copolymers for bulk heterojunctions

    Science.gov (United States)

    Mhamdi, A.; Boukhili, W.; Raissi, M.; Mahdouani, M.; Vignau, L.; Bourguiga, R.

    2016-08-01

    Recently many investigations have been done to improve the performance of solar cells photovoltaic. One of this devices developed is the Bulk Heterojunction (BHJ) solar cells based on poly (3-hexylthiophene) (P3HT)/[6, 6]-phenyl C61-butyric acid methyl ester (PCBM) blend which have been fabricated by spin-coating. It is known that the nanostructure of the active layer of this device has an important impact on the photovoltaic performances. In this work, we analyze the results obtained on solar cells using a copolymer P3HT-b-PS based on poly (3-hexylthiophene) (P3HT) as a donor block and polystyrene (PS) as a soft block, their compatibility with the blend of P3HT/PCBM at various weight percentages (0%-5%). The addition of this weight percentage is in order to improve the performance of polymer solar cells. It has been demonstrated that the addition of a small amount of P3HT-b-PS (from 0.5%-1.5%) led to an increase in photovoltaic efficiency compared to devices made from P3HT/PCBM only. To study the impact of the added amount of the P3HT-b-PS on the performances of the fabricated organic cells, we used an equivalent circuit model based on single diode model with five photovoltaic parameters. Then, we extracted these physical parameters of the organic photovoltaic cells such as the saturation current density, the series and shunt resistances, the ideality factor and the photogenerated current density from the experimental characteristics (J-V) in the dark and under illumination. We proposed and developed the used procedure based on this model and we resolved the analytic equations of the density-current using the Lambert W-function. A good agreement between the theoretical model and the experimental data of electrical characteristics is obtained illustrating the enhancement of the addition of a small amount of P3HT-b-PS (≤1.5%) in the P3HT/PCBM blend on the characteristics of BHJ organic photovoltaic cells.

  2. Interface Engineering of High Efficiency Organic-Silicon Heterojunction Solar Cells.

    Science.gov (United States)

    Yang, Lixia; Liu, Yaoping; Chen, Wei; Wang, Yan; Liang, Huili; Mei, Zengxia; Kuznetsov, Andrej; Du, Xiaolong

    2016-01-13

    Insufficient interface conformity is a challenge faced in hybrid organic-silicon heterojunction solar cells because of using conventional pyramid antireflection texturing provoking the porosity of interface. In this study, we tested alternative textures, in particular rounded pyramids and inverted pyramids to compare the performance. It was remarkably improved delivering 7.61%, 8.91% and 10.04% efficiency employing conventional, rounded, and inverted pyramids, respectively. The result was interpreted in terms of gradually improving conformity of the Ag/organic/silicon interface, together with the gradually decreasing serial resistance. Altogether, the present data may guide further efforts arising the interface engineering for mastering high efficient heterojunction solar cells. PMID:26701061

  3. Structural and Optical Investigations of GaN-Si Interface for a Heterojunction Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Joshua J.; Jeffries, April M.; Bertoni, Mariana I.; Williamson, Todd L.; Bowden, Stuart G.; Honsberg, Christiana B.

    2014-06-08

    In recent years the development of heterojunction silicon based solar cells has gained much attention, lea largely by the efforts of Panasonic’s HIT cell. The success of the HIT cell prompts the scientific exploration of other thin film layers, besides the industrially accepted amorphous silicon. In this paper we report upon the use of gallium nitride, grown by MBE at “low temperatures” (~200°C), on silicon wafers as one possible candidate for making a heterojunction solar cell; the first approximation of band alignments between GaN and Si; and the material quality as determined by X-ray diffraction.

  4. Simulation of a high-efficiency silicon-based heterojunction solar cell

    International Nuclear Information System (INIS)

    The basic parameters of a-Si:H/c-Si heterojunction solar cells, such as layer thickness, doping concentration, a-Si:H/c-Si interface defect density, and the work functions of the transparent conducting oxide (TCO) and back surface field (BSF) layer, are crucial factors that influence the carrier transport properties and the efficiency of the solar cells. The correlations between the carrier transport properties and these parameters and the performance of a-Si:H/c-Si heterojunction solar cells were investigated using the AFORS-HET program. Through the analysis and optimization of a TCO/n-a-Si:H/i-a-Si:H/p-c-Si/p+-a-Si:H/Ag solar cell, a photoelectric conversion efficiency of 27.07% (VOC) 749 mV, JSC: 42.86 mA/cm2, FF: 84.33%) was obtained through simulation. An in-depth understanding of the transport properties can help to improve the efficiency of a-Si:H/c-Si heterojunction solar cells, and provide useful guidance for actual heterojunction with intrinsic thin layer (HIT) solar cell manufacturing. (paper)

  5. Current Status and Future Prospects of Copper Oxide Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Terence K. S. Wong

    2016-04-01

    Full Text Available The current state of thin film heterojunction solar cells based on cuprous oxide (Cu2O, cupric oxide (CuO and copper (III oxide (Cu4O3 is reviewed. These p-type semiconducting oxides prepared by Cu oxidation, sputtering or electrochemical deposition are non-toxic, sustainable photovoltaic materials with application potential for solar electricity. However, defects at the copper oxide heterojunction and film quality are still major constraining factors for achieving high power conversion efficiency, η. Amongst the Cu2O heterojunction devices, a maximum η of 6.1% has been obtained by using pulsed laser deposition (PLD of AlxGa1−xO onto thermal Cu2O doped with Na. The performance of CuO/n-Si heterojunction solar cells formed by magnetron sputtering of CuO is presently limited by both native oxide and Cu rich copper oxide layers at the heterointerface. These interfacial layers can be reduced by using a two-step sputtering process. A high η of 2.88% for CuO heterojunction solar cells has been achieved by incorporation of mixed phase CuO/Cu2O nanopowder. CuO/Cu2O heterojunction solar cells fabricated by electrodeposition and electrochemical doping has a maximum efficiency of 0.64% after surface defect passivation and annealing. Finally, early stage study of Cu4O3/GaN deposited on sapphire substrate has shown a photovoltaic effect and an η of ~10−2%.

  6. Synthesis of New Donor-Acceptor Copolymer and Its Application in Organic Bulk Hetero-junction Solar Cells%新型给体-受体型聚合物的合成及其在本体异质结聚合物太阳能电池中的应用

    Institute of Scientific and Technical Information of China (English)

    邹文武; 刘颖; 贾庆明; 葛子义

    2013-01-01

    设计、合成了侧链含有强吸电结构的丙二酸二丁酯受体单元与苯并[1,2-b∶4,5-b']二噻吩给体单元交替共聚物PBDTDT,研究了其热学、光学、电化学性质以及与受体PC71BM([6,6]-苯基C71丁酸甲酯)共混作为活性层制备成本体异质结聚合物有机太阳能电池的光伏性质,考察了PBDTDT与PC71BM不同比例时的光伏性能,当聚合物PBDTDT和PC71BM质量比为1∶3制备的器件,其开路电压达到了0.82V,能量转换效率(PCE)为0.90%,短路电流为3.25 mA/cm2,填充因子FF为0.338,同时将其与同等工艺制备的poly(3-hexylthiophene) (P3HT)太阳能电池的光伏性能进行比较,相同工艺下制备的P3HT电池的开路电压仅为0.55 V,由PBDTDT制备的电池开路电压比P3HT电池的开路电压高出0.29V,同时分析了PBDTDT能量转换效率较P3HT低的原因.%Altemative copolymer (PBDTDT) was synthesized from acceptor unit with strong electro-withdrawing structure of dibutyl malonate in branch chain and donor unit based on benzo[1,2-b∶4,5-b']dithiophene.And its thermal,optical,electrochemical properties and photovoltaic properties blending with [6,6]-phenyl-C71 butyric acid methyl ester as the active layer in the bulk hetero-junction devices of organic solar cells were investigated.The influence of different ratio of polymer PBDTDT and PC71BM on the photovoltaic properties was also studied.And the open voltage reached 0.82 V,when the weight ratio of PBDTDT and PC71BM is 1 ∶ 3,and its power conversion efficiency (PCE) was 0.90%,with Voc of 0.82 V,Jsc of 3.25 mA/cm2 and FF of 33.8%.Comparing with the poly(3-hexylthiophene) (P3HT) in the same method,the solar cells with P3HT blending with PC71BM as the active layer can only get 0.55 V,which can be lower about 0.29 V than that of the PBDTDT.And the possible factors resulting in low PCE and the higher open voltage than that of P3HT were analyzed.

  7. Dipyrrolidinyl-substituted perylene diimide as additive for poly(3-hexylthiophene): [6,6]-Phenyl C61 butyric acid methylester bulk-heterojunction blends

    Energy Technology Data Exchange (ETDEWEB)

    Vivo, Paola, E-mail: paola.vivo@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Dubey, Rajeev; Lehtonen, Elina; Kivistö, Hannele [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Vuorinen, Tommi [VTT Technical Research Centre of Finland, P.O. Box 1300, FI-33101 Tampere (Finland); Lemmetyinen, Helge [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland)

    2013-12-02

    The effects of the addition of 1,7-dipyrrolidinyl-substituted perylene diimide (1,7-PyPDI) to a traditional poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM) bulk-heterojunction blend on the performance of organic solar cells, are described. When the 1,7-PyPDI amount in the mixture is accurately tuned, the power conversion efficiency (η) of the 1,7-PyPDI-doped cells is enhanced compared to a reference non-doped device. Cells fabricated by spin-coating blends from chloroform solution with P3HT (monomer):PCBM:1,7-PyPDI molar ratio of 6.85:1:0.03 resulted in 39.6% higher power conversion efficiency than P3HT:PCBM blend. The efficiency improvement is attributed to possible photochemical interactions between the three components of the blend, which contribute to enhance the charge separation, and minimize the charge recombination processes. Moreover, the increased absorption and the microstructural implications induced by the introduction of 1,7-PyPDI contribute to explain the enhancement of the solar cell performance. - Highlights: • The solar cell active layer is doped with perylene derivative in different ratios. • The addition of the dopant significantly enhances the solar cell efficiency. • The possible role of the dopant in the heart of the solar cell is discussed.

  8. The role of spin exchange in charge transfer in low-bandgap polymer: Fullerene bulk heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Krinichnyi, V. I., E-mail: kivirus@gmail.com; Yudanova, E. I.; Denisov, N. N. [Kinetics and Catalysis, Institute of Problems of Chemical Physics, Chernogolovka 142432 (Russian Federation)

    2014-07-28

    Formation, relaxation and dynamics of polarons and methanofullerene anion radicals photoinitiated in poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′-benzothiadiazole)]:-[6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCDTBT:PC{sub 61}BM) bulk heterojunctions were studied mainly by light-induced EPR (LEPR) spectroscopy in wide photon energy and temperature ranges. Some polarons are pinned by spin traps whose number and depth are governed by the composite morphology and photon energy. The proximity of the photon energy and the polymer bandgap reduces the number of such traps, inhibits recombination of mobile charge carriers, and facilitates their mobility in polymer network. Spin relaxation and charge carrier dynamics were studied by the steady-state saturation method at wide range of temperature and photon energy. These processes were shown to be governed by spin exchange as well as by the photon energy. Charge transfer in the composite is governed by the polaron scattering on the lattice phonons of crystalline domains embedded into amorphous polymer matrix and its activation hopping between polymer layers. The energy barrier required for polaron interchain hopping exceeds that of its intrachain diffusion. Anisotropy of polaron dynamics in the PCDTBT:PC61BM composite is less than that of poly(3-alkylthiophenes)-based systems that evidences for better ordering of the former. Lorentzian shape of LEPR lines of both charge carriers, lower concentration of spin traps as well as behaviours of the main magnetic resonance parameters were explained by layer ordered morphology of polymer matrix.

  9. Petascale Simulations of the Morphology and the Molecular Interface of Bulk Heterojunctions.

    Science.gov (United States)

    Carrillo, Jan-Michael Y; Seibers, Zach; Kumar, Rajeev; Matheson, Michael A; Ankner, John F; Goswami, Monojoy; Bhaskaran-Nair, Kiran; Shelton, William A; Sumpter, Bobby G; Kilbey, S Michael

    2016-07-26

    Understanding how additives interact and segregate within bulk heterojunction (BHJ) thin films is critical for exercising control over structure at multiple length scales and delivering improvements in photovoltaic performance. The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends that are commensurate with the size of a BHJ thin film is examined using petascale coarse-grained molecular dynamics simulations. Comparisons between two-component and three-component systems containing short P3HT chains as additives undergoing thermal annealing demonstrate that the short chains alter the morphology in apparently useful ways: they efficiently migrate to the P3HT/PCBM interface, increasing the P3HT domain size and interfacial area. Simulation results agree with depth profiles determined from neutron reflectometry measurements that reveal PCBM enrichment near substrate and air interfaces but a decrease in that PCBM enrichment when a small amount of short P3HT chains are integrated into the BHJ blend. Atomistic simulations of the P3HT/PCBM blend interfaces show a nonmonotonic dependence of the interfacial thickness as a function of number of repeat units in the oligomeric P3HT additive, and the thiophene rings orient parallel to the interfacial plane as they approach the PCBM domain. Using the nanoscale geometries of the P3HT oligomers, LUMO and HOMO energy levels calculated by density functional theory are found to be invariant across the donor/acceptor interface. These connections between additives, processing, and morphology at all length scales are generally useful for efforts to improve device performance. PMID:27299676

  10. Fluorene-based narrow-band-gap copolymers for red light- emitting diodes and bulk heterojunction photovoltaic cells

    Institute of Scientific and Technical Information of China (English)

    Mingliang SUN; Li WANG; Yangjun XIA; Bin DU; Ransheng LIU; Yong CAO

    2008-01-01

    A series of narrow band-gap conjugated copo-lymers (PFO-DDQ) derived from 9,9-dioctylfluorene (DOF) and 2,3-dimethyl-5,8-dithien-2-yl-quinoxalines (DDQ) is prepaid by the palladium-catalyzed Suzuki coupling reaction with the molar feed ratio of DDQ at around 1%,5%,15%,30% and 50%,respectively.The obtained polymers are readily soluble in common organic solvents.The solutions and the thin solid films of the copolymers absorb light from 300-590 nm with two absorbance.peaks at around 380 and 490 nm.The intens-ity of 490 nm peak increases with the increasing DDQ content in the polymers.Efficient energy transfer due to exciton trapping on narrow-band-gap DDQ sites has been observed.The PL emission consists exclusively of DDQ unit emission at around 591 643 nm depending on the DDQ content in solid film.The EL emission peaks are red-shifted from 580 nm for PFO-DDQ1 to 635 nm for PFO-DDQ50.The highest external quantum efficiency achieved with the device configuration ITO/PEDOT/ PVK/PFO-DDQt5/Ba/A1 is 1.33% with a luminous effi-ciency 1.54 cd/A.Bulk heterojunction photovoltaic cells fabricated from composite films of PFO-DDQ30 copoly-mer and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) as electron donor and electron acceptor,respect-ively in device configuration:ITO/PEDOT:PSS/PFO-DDQ30:PCBM/PFPNBr/Al shows power conversion effi-ciencies of 1.18% with open-circuit voltage (Voc) of 0.90 V and short-circuit current density (Jsc) of 2.66 mA/cm2 under an AM1.5 solar simulator (100 mW/cm2).The photocurrent response wavelengths of the PVCs based on PFO-DDQ30/PCBM blends covers 300-700 nm.This indicates that these kinds of low band-gap polymers are promising candidates for polymeric solar cells and red light-emitting diodes.

  11. Electroluminescence of a-Si/c-Si heterojunction solar cells after high energy irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ferrara, Manuela

    2009-11-24

    The crystalline silicon as absorber material will certainly continue to dominate the market for space applications of solar cells. In the contribution under consideration the applicability of a-Si:H/c-Si heterojunction solar cells in space has been tested by the investigation of the cell modification by high energy protons and comparing the results to the degradation of homojunction crystalline silicon reference cells. The investigated solar cells have been irradiated with protons of different energies and doses. For all investigated solar cells the maximum damage happens for an energy of about 1.7 MeV and is mainly due to the decrease of the effective minority carrier diffusion length in the crystalline silicon absorber. Simulations carried out by AFORS-HET, a heterojunction simulation program, also confirmed this result. The main degradation mechanism for all types of devices is the monotonically decreasing charge carrier diffusion length in the p-type monocrystalline silicon absorber layer. For the heterojunction solar cell an enhancement of the photocurrent in the blue wavelength region has been observed but only in the case of heterojunction solar cell with intrinsic a-Si:H buffer layer. Additionally to the traditional characterization techniques the electroluminescence technique used for monitoring the modifications of the heteroluminescence technique used for monitoring the modifications of the heterointerface between amorphous silicon and crystalline silicon in solar cells after proton irradiation. A direct relation between minority carrier diffusion length and electroluminescence quantum efficiency has been observed but also details of the interface modification could be monitored by this technique.

  12. Morphological Control for High Performance, Solution-Processed Planar Heterojunction Perovskite Solar Cells

    KAUST Repository

    Eperon, Giles E.

    2013-09-09

    Organometal trihalide perovskite based solar cells have exhibited the highest efficiencies to-date when incorporated into mesostructured composites. However, thin solid films of a perovskite absorber should be capable of operating at the highest efficiency in a simple planar heterojunction configuration. Here, it is shown that film morphology is a critical issue in planar heterojunction CH3NH3PbI3-xCl x solar cells. The morphology is carefully controlled by varying processing conditions, and it is demonstrated that the highest photocurrents are attainable only with the highest perovskite surface coverages. With optimized solution based film formation, power conversion efficiencies of up to 11.4% are achieved, the first report of efficiencies above 10% in fully thin-film solution processed perovskite solar cells with no mesoporous layer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Laterally Ordered Bulk Heterojunction of Conjugated Polymers : Nanoskiving a Jelly Roll

    NARCIS (Netherlands)

    Lipomi, Darren J.; Chiechi, Ryan C.; Reus, William F.; Whitesides, George M.

    2008-01-01

    This paper describes the fabrication of a nanostructured heterojunction of two conjugated polymers by a three-step process: i) spin-coating a multilayered film of the two polymers, ii) rolling the film into a cylinder (a ‘‘jelly roll’’) and iii) sectioning the film perpendicular to the axis of the r

  14. Spin signatures of photogenerated radical anions in polymer-[70]fullerene bulk-heterojunctions : high-frequency pulsed EPR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, O. G.; Filippone, S.; Martin, N.; Sperlich, A.; Deibel, C.; Dyakonov, V. (Chemical Sciences and Engineering Division); (Univ. Complutense de Madrid); (Univ. of Wurzburg)

    2010-04-14

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C{sub 60}-PCBM), and two different soluble C{sub 70}-derivates: C{sub 70}-PCBM and diphenylmethano[70]fullerene oligoether (C{sub 70}-DPM-OE). The first experimental identification of the negative polaron localized on the C{sub 70}-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P{sup +} and P{sup -} in PHT-C{sub 70} bulk heterojunctions. Comparing signals from C{sub 70}-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C{sub 70} molecule.

  15. Spin Signatures of Photogenerated Radical Anions in Polymer-[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, Oleg G. [Argonne National Lab. (ANL), Argonne, IL (United States); Filippone, Salvatore [Universidad Complutense de Madrid (Spain); Martin, C. R. [Universidad Complutense de Madrid (Spain); Sperlich, Andreas [Julius-Maximilians Univ. of Wurzburg (Germany); Deibel, Carsten [Julius-Maximilians Univ. of Wurzburg (Germany); Dyakonov, Vladimir [Julius-Maximilians Univ. of Wurzburg (Germany)

    2010-11-18

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C60-PCBM), and two different soluble C70-derivates: C70-PCBM and diphenylmethano[70]fullerene oligoether (C70-DPM-OE). The first experimental identification of the negative polaron localized on the C70-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P+ and P- in PHT-C70 bulk heterojunctions. Comparing signals from C70-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C70 molecule.

  16. Spin signatures of photogenerated radical anions in polymer-[70]fullerene bulk heterojunctions: high frequency pulsed EPR spectroscopy.

    Science.gov (United States)

    Poluektov, Oleg G; Filippone, Salvatore; Martín, Nazario; Sperlich, Andreas; Deibel, Carsten; Dyakonov, Vladimir

    2010-11-18

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C(60)-PCBM), and two different soluble C(70)-derivates: C(70)-PCBM and diphenylmethano[70]fullerene oligoether (C(70)-DPM-OE). The first experimental identification of the negative polaron localized on the C(70)-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P(+) and P(-) in PHT-C(70) bulk heterojunctions. Comparing signals from C(70)-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C(70) molecule.

  17. Spin signatures of photogenerated radical anions in polymer-[70] fullerene bulk-heterojunctions : high-frequency pulsed EPR spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Poluektov, O. G.; Filippone, S.; Martin, N.; Sperlich, A.; Deibel, C.; Dyakonov, V. (Chemical Sciences and Engineering Division); (Univ. Complutense de Madrid); (Univ. of Wurzburg)

    2010-01-01

    Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C{sub 60}-PCBM), and two different soluble C{sub 70}-derivates: C{sub 70}-PCBM and diphenylmethano[70]fullerene oligoether (C{sub 70}-DPM-OE). The first experimental identification of the negative polaron localized on the C{sub 70}-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P{sup +} and P{sup -} in PHT-C{sub 70} bulk heterojunctions. Comparing signals from C{sub 70}-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C{sub 70} molecule.

  18. Carbon/Silicon Heterojunction Solar Cells: State of the Art and Prospects.

    Science.gov (United States)

    Li, Xinming; Lv, Zheng; Zhu, Hongwei

    2015-11-01

    In the last few decades, advances and breakthroughs of carbon materials have been witnessed in both scientific fundamentals and potential applications. The combination of carbon materials with traditional silicon semiconductors to fabricate solar cells has been a promising field of carbon science. The power conversion efficiency has reached 15-17% with an astonishing speed, and the diversity of systems stimulates interest in further research. Here, the historical development and state-of-the-art carbon/silicon heterojunction solar cells are covered. Firstly, the basic concept and mechanism of carbon/silicon solar cells are introduced with a specific focus on solar cells assembled with carbon nanotubes and graphene due to their unique structures and properties. Then, several key technologies with special electrical and optical designs are introduced to improve the cell performance, such as chemical doping, interface passivation, anti-reflection coatings, and textured surfaces. Finally, potential pathways and opportunities based on the carbon/silicon heterojunction are envisaged. The aspects discussed here may enable researchers to better understand the photovoltaic effect of carbon/silicon heterojunctions and to optimize the design of graphene-based photodevices for a wide range of applications. PMID:26422457

  19. Insights into the Rational Design of Multi-Functional Fullerene Systems for Application in Blended Heterojunction Organic Solar Cells

    Science.gov (United States)

    Cowart, John S., Jr.

    Elucidating the structure-function relationships of organic semiconductors has been central to the advancement of organic photovoltaics (OPVs). In particular, enhancing the performance of p-type materials in disordered heterojunctions is broadly acknowledged as the principal factor leading to current trends of improved power conversion efficiencies (PCEs). However, two additional factors are crucially important for the next step forward in improving PCEs. First, investigating the influence, design and synthesis of new n-type materials, specifically fullerene acceptors, is of high importance. Second, because fullerene performance is often compromised by the morphological disorder of bulk heterojunctions, developing fullerenes systems that retain fidelity within disordered blends is also of broad interest. In light of these challenges, the field has witnessed a notable shift towards developing a comprehensive understanding of the design rules needed to advance the performance of fullerene acceptors in bulk heterojunctions. This work spotlights two multi-functional fullerene systems designed for blended heterojunctions. First, the synthesis of several novel fullerene-dye adducts with enhanced photon absorption will be presented. The ability of these adducts to absorb visible light in their pure state was evaluated and systematically examined versus their capacity to complement the absorption of low band gap donors and mediate charge transport in bulk heterojunctions. Second, mixed fullerene ternary blends were introduced as a strategy to stabilize the morphology in bulk heterojunctions and prolong operational lifetimes of OPV devices. Combined, these two systems offer unique insight into the rational design of fullerenes for their application in blended systems.

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27347923

  1. 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.

  2. Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem to Produce Highly Efficient Solar Cell

    OpenAIRE

    Asadpour, Reza; Chavali, Raghu V. K.; Khan, M. Ryyan; Alam, Muhammad A.

    2015-01-01

    As single junction thin-film technologies, both Si heterojunction (HIT) and Perovskite based solar cells promise high efficiencies at low cost. One expects that a tandem cell design with these cells connected in series will improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics, however, we find that a traditional series connected tandem design suffers from low Jsc due to band-gap mismatch and current matching constraints. It requir...

  3. Novel Semiconductor-Liquid Heterojunction Solar Cells Based on Cuprous Oxide and Iodine Electrolyte

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: •A novel Cu2O-electrolyte heterojunction solar cell was fabricated on a Cu foil substrate. •The novel solar cell was composed of a Cu2O electrode, electrolyte, and a Pt electrode. •A chemical oxidation method was used to fabricate coral-shaped Cu2O structures. •The influence of various iodine concentrations on device efficiency was studied. -- ABSTRACT: In this study, we report a novel cuprous oxide-electrolyte heterojunction solar cell fabricated on a copper foil substrate. A chemical oxidation method was used to fabricate a cuprous oxide electrode that was then combined with an electrolyte and platinum electrode to form a cuprous oxide-electrolyte heterojunction solar cell. Various analytic technologies were employed to characterize the cuprous oxide electrodes. Scanning electron microscopy (SEM) was employed to observe the surface morphology; energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used to characterize the material properties; and ultraviolet-visible (UV-vis) spectroscopy was used to analyze the optical properties of the cuprous oxide. The results show that the particle size of the cuprous oxide ranged from approximately 1–2 μm, which agglomerated and formed coral-shaped structures with lengths and widths of 10–20 and 5–6 μm, respectively, and with absorption wavelengths of 300 to 640 nm. The cuprous oxide-electrolyte heterojunction solar cell was also characterized, and the influence of various iodine (I2) concentrations on device efficiency was studied. The results show that when the I2 concentration of the electrolyte was 10 mM, the short-circuit current density, open-circuit voltage, fill factor, and device conversion efficiency of the cuprous oxide-electrolyte heterojunction solar cell were 3.52 mA/cm2, 0.64 V, 0.32, and 0.72%, respectively

  4. Simulation of hetero-junction silicon solar cells with AMPS-1D

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Como, Norberto; Morales-Acevedo, Arturo [Centro de Investigacion y de Estudios Avanzados del IPN, Electrical Engineering Department, Avenida IPN No. 2508, 07360 Mexico, D. F. (Mexico)

    2010-01-15

    Mono- and poly-crystalline silicon solar cell modules currently represent between 80% and 90% of the PV world market. The reasons are the stability, robustness and reliability of this kind of solar cells as compared to those of emerging technologies. Then, in the mid-term, silicon solar cells will continue playing an important role for their massive terrestrial application. One important approach is the development of silicon solar cells processed at low temperatures (less than 300 C) by depositing amorphous silicon layers with the purpose of passivating the silicon surface, and avoiding the degradation suffered by silicon when processed at temperatures above 800 C. This kind of solar cells is known as HIT cells (hetero-junction with an intrinsic thin amorphous layer) and are already produced commercially (Sanyo Ltd.), reaching efficiencies above 20%. In this work, HIT solar cells are simulated by means of AMPS-1D, which is a program developed at Pennsylvania State University. We shall discuss the modifications required by AMPS-1D for simulating this kind of structures since this program explicitly does not take into account interfaces with high interfacial density of states as occurs at amorphous-crystalline silicon hetero-junctions. (author)

  5. Fabrication of ZnO/Cu2O heterojunctions in atmospheric conditions: Improved interface quality and solar cell performance

    OpenAIRE

    Ievskaya, Y.; Hoye, R.L.Z.; Sadhanala, A.; Musselman, K. P.; MacManus-Driscoll, J. L.

    2014-01-01

    Zn_1-xMg_xO/Cu_2O heterojunctions were successfully fabricated in open-air at low temperatures via atmospheric atomic layer deposition of Zn_1-xMg_xO on thermally oxidized cuprous oxide. Solar cells employing these heterojunctions demonstrated a power conversion efficiency exceeding 2.2% and an open-circuit voltage of 0.65 V. Surface oxidation of Cu_2O to CuO prior to and during Zn_1-xMg_xO deposition was identified as the limiting factor to obtaining a high quality heterojunction interface. ...

  6. Development, characterization and modeling of interfaces for high efficiency silicon heterojunction solar cells

    OpenAIRE

    Varache, Renaud

    2012-01-01

    The interface between amorphous silicon (a-Si:H) and crystalline silicon (c-Si) is the building block of high efficiency solar cells based on low temperature fabrication processes. Three properties of the interface determine the performance of silicon heterojunction solar cells: band offsets between a-Si:H and c-Si, interface defects and band bending in c-Si. These three points are addressed in this thesis.First, an analytical model for the calculation of the band bending in c-Si is developed...

  7. Electronic properties of Mn-phthalocyanine–C{sub 60} bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Friedrich [Center for Free-Electron Laser Science/DESY, Notkestraße 85, D-22607 Hamburg (Germany); Herzig, Melanie; Knupfer, Martin [FW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Lupulescu, Cosmin [Institute of Optics and Atomic Physics, TU Berlin, Straße des 17. Juni 135, D-10623 Berlin (Germany); Darlatt, Erik; Gottwald, Alexander [Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, D-10587 Berlin (Germany); Eberhardt, Wolfgang [Center for Free-Electron Laser Science/DESY, Notkestraße 85, D-22607 Hamburg (Germany); Institute of Optics and Atomic Physics, TU Berlin, Straße des 17. Juni 135, D-10623 Berlin (Germany)

    2015-11-14

    The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C{sub 60} (MnPc:C{sub 60}) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C{sub 60}. Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C{sub 60} bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C{sub 60} to MnPc thin films.

  8. Dominance of interface chemistry over the bulk properties in determining the electronic structure of epitaxial metal/perovskite oxide heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, Scott A.; Du, Yingge; Gu, Meng; Droubay, Timothy C.; Hepplestone, Steven; Sushko, Petr

    2015-06-09

    We show that despite very similar crystallographic properties and work function values in the bulk, epitaxial Fe and Cr metallizations on Nb:SrTiO3(001) generate completely different heterojunction electronic properties. Cr is Ohmic whereas Fe forms a Schottky barrier with a barrier height of 0.50 eV. This contrast arises because of differences in interface chemistry. In contrast to Cr [Chambers, S. A. et al., Adv. Mater. 2013, 25, 4001.], Fe exhibits a +2 oxidation state and occupies Ti sites in the perovskite lattice, resulting in negligible charge transfer to Ti, upward band bending, and Schottky barrier formation. The differences between Cr and Fe are understood by performing first-principles calculations of the energetics of defect formation which corroborate the observed interface chemistry and structure.

  9. Origin of the high open circuit voltage in planar heterojunction perovskite solar cells: Role of the reduced bimolecular recombination

    Science.gov (United States)

    Yang, Wenchao; Yao, Yao; Wu, Chang-Qin

    2015-03-01

    The high open circuit voltage is an attractive feature for the currently popular organic-inorganic hybrid perovskite solar cells. In this paper, by employing the macroscopic device model simulation, we investigate its origin for the planar heterojunction perovskite solar cells. Based on the calculated current density-voltage characteristics, it is revealed that compared to the excitonic solar cells, the fast thermal-activated exciton dissociation in the bulk due to the small exciton binding energy may improve the short circuit current and the fill factor, but its beneficial role on the open circuit voltage is marginal. The most significant contribution for the open circuit voltage comes from the reduced bimolecular recombination. In the perovskites, with the recombination prefactor many orders of magnitude smaller than that based on the Langevin's theory, the internal charge density level is significantly enhanced and the density gradient is removed, leading to the high quasi-Fermi level splitting and thus the small open circuit voltage loss. For the nonradiative recombination pathway due to the deep trap states, it may induce significant loss of open circuit voltage as the trap density is high, while for the moderately low density its effect on the open circuit voltage is small and negligible.

  10. The influence of post-deposition annealing upon amorphous silicon/crystalline silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mikolášek, Miroslav, E-mail: miroslav.mikolasek@stuba.sk [Slovak University of Technology, Faculty of Electrical Engineering and Information Technology, Ilkovičova 3, 812 19 Bratislava (Slovakia); Nemec, Michal; Kováč, Jaroslav [Slovak University of Technology, Faculty of Electrical Engineering and Information Technology, Ilkovičova 3, 812 19 Bratislava (Slovakia); Foti, Marina; Gerardi, Cosimo [IMS-R and D, STMicroelectronics, Stradale Primosole, 50, 95121 Catania (Italy); Mannino, Giovanni; Valenti, Luca; Lombardo, Salvatore [CNR-IMM, Zona Industriale, Ottava Strada, 5, 95121 Catania (Italy)

    2014-11-15

    Highlights: • We studied the impact of the thermal annealing on the silicon heterojunction solar cells. • Compared were samples deposited by ICP-CVD and PE-CVD methods. • Annealing up to 250 °C improves output performance of both solar cells. • Annealing above 250 °C increases defect states density at the interface and in the amorphous emitter. • Samples deposited by ICP-CVD shows better resistance against annealing. - Abstract: This paper presents a comparative study of the influence of post-deposition annealing on amorphous silicon/crystalline silicon heterojunction solar cells deposited by ICP-CVD and PE-CVD techniques. Two major effects on the solar cell efficiency occur caused by thermal annealing. The first effect is a slight improvement of the performance on annealing up to 250 °C. The second effect, for annealing temperatures above 250 °C, reveals deterioration of the solar cell performance. It is suggested that both effects are related to thermally activated diffusion of hydrogen. For low annealing temperatures, diffusion of weakly bonded hydrogen allows to passivate the defects in the amorphous emitter and at the heterointerface. In the high temperature annealing region, outdiffusion of hydrogen is assumed to be responsible for an increase of defect states in the structures. The results indicate a better stability after high temperature treatment for the sample prepared by ICP-CVD technology.

  11. Mesoscopic CH 3 NH 3 PbI 3 /TiO 2 Heterojunction Solar Cells

    KAUST Repository

    Etgar, Lioz

    2012-10-24

    We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH 3NH 3PbI 3) perovskite/TiO 2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH 3NH 3I and PbI 2 in γ-butyrolactone on a 400 nm thick film of TiO 2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH 3NH 3PbI 3 as a back contact. Importantly, the CH 3NH 3PbI 3 nanoparticles assume here simultaneously the roles of both light harvester and hole conductor, rendering superfluous the use of an additional hole transporting material. The simple mesoscopic CH 3NH 3PbI 3/TiO 2 heterojunction solar cell shows impressive photovoltaic performance, with short-circuit photocurrent J sc= 16.1 mA/cm 2, open-circuit photovoltage V oc = 0.631 V, and a fill factor FF = 0.57, corresponding to a light to electric power conversion efficiency (PCE) of 5.5% under standard AM 1.5 solar light of 1000 W/m 2 intensity. At a lower light intensity of 100W/m 2, a PCE of 7.3% was measured. The advent of such simple solution-processed mesoscopic heterojunction solar cells paves the way to realize low-cost, high-efficiency solar cells. © 2012 American Chemical Society.

  12. Simulation of interdigitated back-contact silicon heterojunction solar cells with quantum transport model

    Science.gov (United States)

    Kamioka, Takefumi; Hayashi, Yutaka; Nakamura, Kyotaro; Ohshita, Yoshio

    2015-08-01

    A simulation of interdigitated back-contact silicon heterojunction (IBC-SHJ) solar cells was performed using a quantum transport model to consider the quantum effect at the crystalline/amorphous (c/a) heterojunction interface. It was found that the impact of the quantum effect on the open-circuit voltage is comparable to that of the interface defect density at the c/a interface, indicating the importance of implementation of the quantum model. The optimal back-contact design was also discussed from the viewpoint of mass production, in which the design rule is relaxed. The degradation of the conversion efficiency by widening the gap between the p- and n-aSi:H layers can be compensated by improving passivation quality at the c/a interface.

  13. Band alignment measurements at heterojunction interfaces in layered thin film solar cells & thermoelectrics

    Science.gov (United States)

    Fang, Fang

    2011-12-01

    combination of core levels and valence band ultraviolet photoemission spectra of the bulk materials as well as the heterojunction (Sb2Te 3/Bi2Te3), the VBO at p-type Sb2Te 3 and n-type Bi2Te3 is determined as 0.04 +/- 0.10 eV. Such a small energy offset is within the same magnitude of the thermal energy of kT, at room temperature. The motivation for the II-VI ZnTe-based thin film solar cell derives from the need to identify and overcome performance-limiting properties related to the processing of film deposition using close space sublimation (CSS). Chemical and electronic properties of the CSS grown ZnTe/ZnSe films were studied in x-ray diffraction, scanning electron microscopy and photoemission spectroscopy. Specifically, Se oxide was observed on the ZnSe surface, the removal of this oxide generated apparent offsets in the valence band and hence the alignment at the heterojunction energy diagram. Processing steps to mitigate oxidation yielded the best cells. Film structure was studied on the dependence of growth time; physical film damage is found during the initial stages when depositing ZnTe on a grown ZnSe film. Preliminary studies of films grown by evaporation and their characterizations are presented at last. In this thesis, a better understanding of the electronic structure at interfaces is built in two different thin film devices, and the resulting band energy diagram of the corresponding devices offered effective feedback in materials and device.The problem of energy equilibrium in the human body has received a great deal.

  14. Advances in colloidal quantum dot solar cells: The depleted-heterojunction device

    International Nuclear Information System (INIS)

    Colloidal quantum dot (CQD) photovoltaics combine low-cost solution processibility with quantum size-effect tunability to match absorption with the solar spectrum. Recent advances in CQD photovoltaics have led to 3.6% AM1.5 solar power conversion efficiencies. Here we report CQD photovoltaic devices on transparent conductive oxides and show that our devices rely on the establishment of a depletion region for field-driven charge transport and separation. The resultant depleted-heterojunction solar cells provide a 5.1% AM1.5 power conversion efficiency. The devices employ infrared-bandgap size-effect-tuned PbS colloidal quantum dots, enabling broadband harvesting of the solar spectrum.

  15. RETRACTED: Advances in colloidal quantum dot solar cells: The depleted-heterojunction device

    KAUST Repository

    Kramer, Illan J.

    2011-08-01

    Colloidal quantum dot (CQD) photovoltaics combine low-cost solution processibility with quantum size-effect tunability to match absorption with the solar spectrum. Recent advances in CQD photovoltaics have led to 3.6% AM1.5 solar power conversion efficiencies. Here we report CQD photovoltaic devices on transparent conductive oxides and show that our devices rely on the establishment of a depletion region for field-driven charge transport and separation. The resultant depleted-heterojunction solar cells provide a 5.1% AM1.5 power conversion efficiency. The devices employ infrared-bandgap size-effect-tuned PbS colloidal quantum dots, enabling broadband harvesting of the solar spectrum. © 2010 Elsevier B.V.

  16. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

    Science.gov (United States)

    Zhang, Jianhua; Li, Fushan; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-04-01

    In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH3NH3PbI3 perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm-2, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

  17. Characteristics of Polyaniline/Si Heterojunction Solar Cell By Electrochemical Dye Sensitization

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jian-bang; REN Ju; HOU Chao-qi

    2005-01-01

    Using the electrochemical polymerization dye sensitization(ECDS) method, polyaniline (PAn),which is used as top region material in solar cells, is sensitized with direct blue dye(DS), and sensitized Al grid/DS-PAn/n-Si/Al heterojunction solar cells is prepared by ECDS. Influences of the ECDS on the absorption spectrum and the junction characteristics of the solar cell were discussed, and the output characteristics were measured. The results show that the absorption spectrum of the sensitized PAn films is much wider and stronger in Vis-range; the diode quality factor is about 6.3 and the height of latent barrier potential of p-n junction is 0.89 eV; the short-circuit current and the conversion efficiency of sensitized DSPAn/Si heterojunction solar cells are greatly improved, which the short-circuit current can increase 6 times,the fill factor is 57% and the efficiency can reach 1.42% under the illumination of 37.2 W/m2 , respectively.

  18. High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

    International Nuclear Information System (INIS)

    We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cell or a CH3NH3PbI3 perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells

  19. High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

    Energy Technology Data Exchange (ETDEWEB)

    Uzu, Hisashi, E-mail: Hisashi.Uzu@kaneka.co.jp, E-mail: npark@skku.edu; Ichikawa, Mitsuru; Hino, Masashi; Nakano, Kunihiro; Meguro, Tomomi; Yamamoto, Kenji [Kaneka Corporation, 5-1-1, Torikai-Nishi, Settsu, Osaka 566-0072 (Japan); Hernández, José Luis [Kaneka Belgium N.V., Nijverheidsstraat 16, 2260 Westerlo-Oevel (Belgium); Kim, Hui-Seon; Park, Nam-Gyu, E-mail: Hisashi.Uzu@kaneka.co.jp, E-mail: npark@skku.edu [School of Chemical Engineering and Department of Energy Science, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2015-01-05

    We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cell or a CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.

  20. Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells

    OpenAIRE

    Seif, Johannes Peter; Descoeudres, Antoine; Filipic, Miha; Smole, Franc; Topic, Marko; Holman, Zachary Charles; De Wolf, Stefaan; Ballif, Christophe

    2014-01-01

    In amorphous/crystalline silicon heterojunction solar cells, optical losses can be mitigated by replacing the amorphous silicon films by wider bandgap amorphous silicon oxide layers. In this article, we use stacks of intrinsic amorphous silicon and amorphous silicon oxide as front intrinsic buffer layers and show that this increases the short-circuit current density by up to 0.43 mA/cm2 due to less reflection and a higher transparency at short wavelengths. Additionally, high open-circuit volt...

  1. p-type Mesoscopic Nickel Oxide/Organometallic Perovskite Heterojunction Solar Cells

    OpenAIRE

    Kuo-Chin Wang; Jun-Yuan Jeng; Po-Shen Shen; Yu-Cheng Chang; Eric Wei-Guang Diau; Cheng-Hung Tsai; Tzu-Yang Chao; Hsu-Cheng Hsu; Pei-Ying Lin; Peter Chen; Tzung-Fang Guo; Ten-Chin Wen

    2014-01-01

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact ...

  2. Interface defects in a-Si:H/c-Si heterojunction solar cells

    Science.gov (United States)

    Defresne, A.; Plantevin, O.; Sobkowicz, I. P.; Bourçois, J.; Roca i Cabarrocas, P.

    2015-12-01

    The ability to incorporate a low concentration of defects at different near-surface or interface locations in a silicon heterojunction solar cell is reported here using argon ion implantation. Optical properties of the irradiated layers are addressed using spectroscopic ellipsometry while non-radiative recombinations through defects are addressed using photoconductance and photoluminescence measurements. Low energy ion irradiation at 1 keV under fluences up to 7 × 1013 cm-2 induces no cell degradation while higher ion energies associated to larger penetration depths close to the amorphous/crystalline interface show increased degradation with ion fluence. This behavior allows to estimate some interface defect concentration threshold for cell degradation.

  3. Influences of Low Energy Ion Implantation on Properties of Polyaniline/Si Heterojunction Solar Cells

    Institute of Scientific and Technical Information of China (English)

    WU Chang-jiang; ZHENG Jian-bang; LI En-pu

    2005-01-01

    Ion implantation may favorably modify the properties ofpolyaniline/Si heterojunction solar cells fabricated by the electrochemical method. Influences of the implantation on the absorption spectrum and the thermal stability were discussed and output properties were measured. The results show that the absorption spectrum of the polyaniline films modified by ion implantation is much wider; its pyrolytic temperature increases by 40℃, and the polyaniline/Si cell efficiency increases 18 and 3 times under the illumination of 10.92 and 37.2 W/m2, respectively.

  4. a-Si/c-Si heterojunction solar cells on SiSiC ceramic substrates

    Institute of Scientific and Technical Information of China (English)

    LI Xudong; XU Ying; CHE Xiaoqi

    2006-01-01

    Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great changein cell's structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell's efficiency.A conversion efficiency of 3.42% has been achieved on 1cm2 a-Si/c-Si heterojunction solar cell ( Isc =16.93 mA, Voc =310.9 mV, FF =06493, AM =1.5 G,24 ℃), while the cell with diffused homojunction only gotan efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.

  5. Laser Induced Forward Transfer for front contact improvement in silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Colina, M., E-mail: monicacolinb@gmail.com; Morales-Vilches, A.; Voz, C.; Martín, I.; Ortega, P.; Orpella, A.; López, G.; Alcubilla, R.

    2015-05-01

    Highlights: • LIFT technique is investigated to improve heterojunction HJ solar cells. • Doped silicon films are adequate precursors for LIFT application in HJ cells. • LIFT leads to a reduction of the series resistance of a-Si HJ diodes. • LIFT allows the improvement of the front contact resistance in a-Si HJ solar cells. - Abstract: In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms occurs when a sequence of laser pulses impinging onto the doped layer propels the material toward the substrate. The laser irradiation not only transfers the doping material but also produces a local heating that promotes its diffusion into the substrate. The laser employed was a 1064 nm, lamp-pumped system, working at pulse durations of 100 and 400 ns. In order to obtain a good electrical performance a comprehensive optimization of the applied laser fluency and number of pulses was carried out. Subsequently, arrays of n + p local junctions were created by LIFT and the resulting J–V curves demonstrated the formation of good quality n+ regions. These structures were finally incorporated to enhance the front contact in conventional silicon heterojunction solar cells leading to an improvement of conversion efficiency.

  6. Laser Induced Forward Transfer for front contact improvement in silicon heterojunction solar cells

    International Nuclear Information System (INIS)

    Highlights: • LIFT technique is investigated to improve heterojunction HJ solar cells. • Doped silicon films are adequate precursors for LIFT application in HJ cells. • LIFT leads to a reduction of the series resistance of a-Si HJ diodes. • LIFT allows the improvement of the front contact resistance in a-Si HJ solar cells. - Abstract: In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms occurs when a sequence of laser pulses impinging onto the doped layer propels the material toward the substrate. The laser irradiation not only transfers the doping material but also produces a local heating that promotes its diffusion into the substrate. The laser employed was a 1064 nm, lamp-pumped system, working at pulse durations of 100 and 400 ns. In order to obtain a good electrical performance a comprehensive optimization of the applied laser fluency and number of pulses was carried out. Subsequently, arrays of n + p local junctions were created by LIFT and the resulting J–V curves demonstrated the formation of good quality n+ regions. These structures were finally incorporated to enhance the front contact in conventional silicon heterojunction solar cells leading to an improvement of conversion efficiency

  7. Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

    Science.gov (United States)

    Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

    2012-12-21

    Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

  8. Solvent Vapor Treatment Effects on Poly(3-hexylthiophene Thin Films and its Application for Interpenetrating Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Masanori Ozaki

    2010-11-01

    Full Text Available The solvent vapor treatment (SVT for poly(3-hexylthiophene (PAT6 films and its application to interpenetrating heterojunction organic solar cells have been studied. It was found that SVT could improve the crystallinity and electrical characteristics of the PAT6 films. We fabricated organic solar cells with an interpenetrating structure of PAT6 and fullerenes utilizing the SVT process, and discuss the improved performance of the solar cells by taking the film crystallinity, optical properties, and morphology into consideration.

  9. Depth profiling sulphur in bulk CdTe and {CdTe}/{CdS} thin film heterojunctions

    Science.gov (United States)

    Lane, D. W.; Conibeer, G. J.; Romani, S.; Healy, M. J. F.; Rogers, K. D.

    1998-03-01

    Polycrystalline CdTeCdS heterojunction solar cells are a possible candidate for the low cost, high efficiency conversion of solar energy. The formation of an intermediate CdS xTe 1- x layer during a high temperature annealing stage is believed to increase optical absorption and decrease cell efficiency. S diffusion in single crystal CdTe has been investigated by NRA using the 32S (d,p o) 33S nuclear reaction, at a deuteron energy of 2 MeV. Details of the NRA depth profiling procedure are given, which was found to be relatively straightforward and suitable for use on a small Van de Graaff accelerator. The resulting diffusion parameters are compared to those obtained by SIMS using a Cs + primary ion beam, examining negative secondary ions. The diffusion coefficients were found to be 1.1 × 10 -15cm 2 s -1 at 450°C and ˜8 × 10 -15cm -1 s at 550°C. S diffusion in thin films was also investigated by 2 MeV 4He + RBS on annealed polycrystalline CdSCdTe multilayers.

  10. Degradation mechanism for planar heterojunction perovskite solar cells

    Science.gov (United States)

    Yamamoto, Kouhei; Furumoto, Yoshikazu; Shahiduzzaman, M.; Kuwabara, Takayuki; Takahashi, Kohshin; Taima, Tetsuya

    2016-04-01

    Organic-inorganic hybrid perovskite materials have recently emerged as a promising cost- and energy-efficient light absorber material for photovoltaic applications. Unfortunately, perovskite solar cells have a problem with decreasing power conversion efficiency owing to their degradation in air. To clarify the cause of the degradation of perovskite solar cells, we exposed deposited CH3NH3PbI3 and HC(NH2)2PbI3 films to an O2 or (H2O+N2) atmosphere condition. Analysis of these films revealed that a large energy band gap was observed as a result of the influence of the H2O molecule in CH3NH3PbI3 and HC(NH2)2PbI3. Under the (H2O+N2) atmosphere condition, the existence of CH3NH3I and HC(NH2)2I molecules was found to affect the morphology and as well as the crystalline diffraction peak. The resultant perovskite crystalline structure was degraded by H2O molecules under the air exposure condition.

  11. Silicon Heterojunction Solar Cells: Temperature Impact on Passivation and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Seif, J.; Krishnamani, G.; Demaurex, B.; Martin de Nicholas, S.; Holm, N.; Ballif, C.; De Wolf, S.

    2015-03-23

    Photovoltaic devices deployed in the field can reach operation temperatures (T) as high as 90 °C [1]. Hence, their temperature coefficients (TC1) are of great practical importance as they determine their energy yield. In this study we concentrate on T-related lifetime variations of amorphous/crystalline interfaces and study their influence on the TCs of the individual solar cell parameters. We find that both the open-circuit voltage (Voc) and fill factor (FF) are influenced by these lifetime variations. However, this is only a minor effect compared to the dominant increase of the intrinsic carrier density and the related increase in dark saturation current density. Additionally, in this paper we will show that the TCVoc does not depend solely on the initial value of the Voc [2, 3], but that the structure of the device has to be considered as well.

  12. Numerical study of metal oxide heterojunction solar cells

    Science.gov (United States)

    Zhu, L.; Shao, G.; Luo, J. K.

    2011-08-01

    Metal oxide (MO) semiconductors have great potential for photovoltaic (PV) application owing to some optimal bandgaps and a variety of possible combinations of the materials. The progress is limited due to lack of high-quality materials, reliable process and theoretical study and models which can guide the development. This paper reports on the numerical modelling of MO semiconductor PV cells. The effects of the bandgap structure, material, doping concentration and layer thickness on the proposed oxide solar cells have been investigated. It was found that, in an ideal case of no defects and no interface states, wide-gap MO, CuO and Cu2O can form a heterostructure n+/p/p+ cell with efficiency up to 28.6%, demonstrating great potential for development.

  13. Applied research on 2-6 compound materials for heterojunction solar cells

    Science.gov (United States)

    Bube, R. H.

    1975-01-01

    Several II-VI heterojunctions show promise for photovoltaic conversion of solar energy. The three of greatest interest are p-CdTe/n-CdS, p-CdTe/n-ZnSe, and p-ZnTe/n-CdSe. Several p-CdTe/n-CdS heterojunction cells have been prepared by close spaced transport deposition of p-CdTe on single crystal n-CdS, and by two source vacuum evaporation of n-CdS on single crystal p-CdTe. Both types of cells, in an experimental stage, are quite comparable, exhibiting values of quantum efficiency between 0.5 and 0.9, open circuit voltages between 0.50 and 0.66 V, fill factors between 0.4 and 0.6, and solar efficiencies up to 4 percent. Cells of p-ZnTe/n-CdSe have also been made by close spaced vapor transport deposition of n-CdSe on single crystal p-ZnTe.

  14. Additive to regulate the perovskite crystal film growth in planar heterojunction solar cells

    International Nuclear Information System (INIS)

    We reported a planar heterojunction perovskite solar cell fabricated from MAPbI3−xClx perovskite precursor solution containing 1-chloronaphthalene (CN) additive. The MAPbI3−xClx perovskite films have been characterized by UV-vis, SEM, XRD, and steady-state photoluminescence (PL). UV-vis absorption spectra measurement shows that the absorbance of the film with CN additive is significantly higher than the pristine film and the absorption peak is red shift by 30 nm, indicating the perovskite film with additive possessing better crystal structures. In-situ XRD study of the perovskite films with additive demonstrated intense diffraction peaks from MAPbI3−xClx perovskite crystal planes of (110), (220), and (330). SEM images of the films with additive indicated the films were more smooth and homogenous with fewer pin-holes and voids and better surface coverage than the pristine films. These results implied that the additive CN is beneficial to regulate the crystallization transformation kinetics of perovskite to form high quality crystal films. The steady-state PL measurement suggested that the films with additive contained less charge traps and defects. The planar heterojunction perovskite solar cells fabricated from perovskite precursor solution containing CN additive demonstrated 30% enhancement in performance compared to the devices with pristine films. The improvement in device efficiency is mainly attributed to the good crystal structures, more homogenous film morphology, and also fewer trap centers and defects in the films with the additive

  15. Light-induced EPR study of charge transfer in P3HT/bis-PCBM bulk heterojunctions

    Science.gov (United States)

    Krinichnyi, Victor I.; Yudanova, Eugenia I.

    2011-06-01

    Radical pairs, polarons and fullerene anion radicals photoinduced by photons with energy of 1.98 - 2.73 eV in bulk heterojunctions formed by poly(3-hexylthiophene) (P3HT) with bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6.6]C62 (bis-PCBM) fullerene derivative have been studied by direct light-induced EPR (LEPR) method in a wide temperature range. A part of photoinduced polarons are pinned in trap sites which number and depth are governed by an ordering of the polymer/fullerene system and energy of initiating photons. It was shown that dynamics and recombination of mobile polarons and counter fullerene anion radicals are governed by their exchange- and multi-trap assisted diffusion. Relaxation and dynamics parameters of both the charge carriers were determined separately by the steady-state saturation method. These parameters are governed by structure and conformation of the carriers' microenvironment as well as by the energy of irradiating photons. Longitudinal diffusion of polarons was shown to depend on lattice phonons of crystalline domains embedded into an amorphous polymer matrix. The energy barrier required for polaron interchain hopping is higher than that its intrachain diffusion. Pseudorotation of fullerene derivatives in a polymer matrix was shown to follow the activation Pike model.

  16. Light-induced EPR study of charge transfer in P3HT/bis-PCBM bulk heterojunctions

    Directory of Open Access Journals (Sweden)

    Victor I. Krinichnyi

    2011-06-01

    Full Text Available Radical pairs, polarons and fullerene anion radicals photoinduced by photons with energy of 1.98 – 2.73 eV in bulk heterojunctions formed by poly(3-hexylthiophene (P3HT with bis(1-[3-(methoxycarbonylpropyl]-1-phenyl-[6.6]C62 (bis-PCBM fullerene derivative have been studied by direct light-induced EPR (LEPR method in a wide temperature range. A part of photoinduced polarons are pinned in trap sites which number and depth are governed by an ordering of the polymer/fullerene system and energy of initiating photons. It was shown that dynamics and recombination of mobile polarons and counter fullerene anion radicals are governed by their exchange- and multi-trap assisted diffusion. Relaxation and dynamics parameters of both the charge carriers were determined separately by the steady-state saturation method. These parameters are governed by structure and conformation of the carriers’ microenvironment as well as by the energy of irradiating photons. Longitudinal diffusion of polarons was shown to depend on lattice phonons of crystalline domains embedded into an amorphous polymer matrix. The energy barrier required for polaron interchain hopping is higher than that its intrachain diffusion. Pseudorotation of fullerene derivatives in a polymer matrix was shown to follow the activation Pike model.

  17. The Compromise Condition for High Performance of the Single Silicon Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Youngseok Lee

    2012-01-01

    Full Text Available For optimum performance of the hydrogenated amorphous silicon/crystalline silicon (a-Si : H/c-Si heterojunction solar cells, featuring a doping concentration, localized states, as well as thickness of emitter layer are crucial, since Fermi level, surface passivated quality, and light absorption have to be compromised themselves. For this purpose, the effect of both doping concentration and thickness of emitter layer was investigated. It was found that with gas phase doping concentration and emitter layer thickness of 3% and 7 nm, solar cell efficiency in excess of 14.6% can be achieved. For high gas phase doping concentration, the degradation of open-circuit voltage as well as cell efficiency was obtained due to the higher disorder in the emitter layer. The heavily doped along with thicker in thickness of emitter layer results in light absorption on short wavelength, then diminishing short-circuit current density.

  18. Efficiency Enhancement of Silicon Heterojunction Solar Cells via Photon Management Using Graphene Quantum Dot as Downconverters

    KAUST Repository

    Tsai, Meng-Lin

    2015-12-16

    By employing graphene quantum dots (GQDs), we have achieved a high efficiency of 16.55% in n-type Si heterojunction solar cells. The efficiency enhancement is based on the photon downconversion phenomenon of GQDs to make more photons absorbed in the depletion region for effective carrier separation, leading to the enhanced photovoltaic effect. The short circuit current and the fill factor are increased from 35.31 to 37.47 mA/cm2 and 70.29% to 72.51%, respectively. The work demonstrated here holds the promise for incorporating graphene-based materials in commercially available solar devices for developing ultra-high efficiency photovoltaic cells in the future.

  19. Hybrid organic-inorganic heterojunctions for photovoltaic applications

    OpenAIRE

    Dietmüller, Roland

    2012-01-01

    Hybrid organic-inorganic bulk heterojunction solar cells based on silicon nanocrystals (Si-nc) have been realized and investigated. A photo-induced charge transfer could be demonstrated in composites made of silicon nanocrystals and poly(3-hexylthiophene) (P3HT) or [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) via light-induced electron spin resonance measurements. With bulk heterojunction solar cells made of P3HT/Si-nc composites in a sandwich structure, open-circuit voltages of up to 0....

  20. Highly-Efficient Charge Separation and Polaron Delocalization in Polymer-Fullerene Bulk-Heterojunctions: A Comparative Multi-Frequency EPR & DFT Study

    Science.gov (United States)

    Niklas, Jens; Mardis, Kristy L.; Banks, Brian P.; Grooms, Gregory M.; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G.

    2016-01-01

    delocalization of the positive polaron on the polymer donor is an important reason for the efficient charge separation in bulk heterojunction systems as it minimizes the wasteful process of charge recombination. The combination of advanced EPR spectroscopy and DFT is a powerful approach for investigation of light-induced charge dynamics in organic photovoltaic materials. PMID:23670645

  1. Highly-efficient charge separation and polaron delocalization in polymer-fullerene bulk-heterojunctions: a comparative multi-frequency EPR and DFT study.

    Science.gov (United States)

    Niklas, Jens; Mardis, Kristy L; Banks, Brian P; Grooms, Gregory M; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G

    2013-06-28

    . Strong delocalization of the positive polaron on the polymer donor is an important reason for the efficient charge separation in bulk heterojunction systems as it minimizes the wasteful process of charge recombination. The combination of advanced EPR spectroscopy and DFT is a powerful approach for investigation of light-induced charge dynamics in organic photovoltaic materials.

  2. Bulk fabrication and properties of solar grade silicon microwires

    Directory of Open Access Journals (Sweden)

    F. A. Martinsen

    2014-11-01

    Full Text Available We demonstrate a substrate-free novel route for fabrication of solar grade silicon microwires for photovoltaic applications. The microwires are fabricated from low purity starting material via a bulk molten-core fibre drawing method. In-situ segregation of impurities during the directional solidification of the fibres yields solar grade silicon cores (microwires where the concentration of electrically detrimental transition metals has been reduced between one and two orders of magnitude. The microwires show bulk minority carrier diffusion lengths measuring ∼40 μm, and mobilities comparable to those of single-crystal silicon. Microwires passivated with amorphous silicon yield diffusion lengths comparable to those in the bulk.

  3. Simulation of Hetero-junction (GaInP/GaAs Solar Cell Using AMPS-1D

    Directory of Open Access Journals (Sweden)

    Dennai Benmoussa

    2016-03-01

    Full Text Available Photovoltaic conversion is the direct conversion of electromagnetic energy into electrical energy continuously. This electromagnetic energy is the most solar radiation. In this work we performed a computer modelling using AMPS 1D optimization of hetero-junction solar cells GaInP / GaAs configuration for p/n. We studied the influence of the thickness the base layer in the cell offers on the open circuit voltage, the short circuit current and efficiency.

  4. Simulation of Hetero-junction (GaInP/GaAs) Solar Cell Using AMPS-1D

    OpenAIRE

    Dennai Benmoussa; M. Boukais; H. Benslimane

    2016-01-01

    Photovoltaic conversion is the direct conversion of electromagnetic energy into electrical energy continuously. This electromagnetic energy is the most solar radiation. In this work we performed a computer modelling using AMPS 1D optimization of hetero-junction solar cells GaInP / GaAs configuration for p/n. We studied the influence of the thickness the base layer in the cell offers on the open circuit voltage, the short circuit current and efficiency.

  5. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    Science.gov (United States)

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells. PMID:26926667

  6. Anode interfacial tuning via electron-blocking/hole-transport layers and indium tin oxide surface treatment in bulk-heterojunction organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Hains, Alexander W.; Liu, Jun; Martinson, Alex B.F.; Irwin, Michael D.; Marks, Tobin J. [Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois (United States)

    2010-02-22

    The effects of anode/active layer interface modification in bulk-heterojunction organic photovoltaic (OPV) cells is investigated using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and/or a hole-transporting/electron-blocking blend of 4,4'-bis[(p-trichlorosilylpropylphenyl)-phenylamino]biphenyl (TPDSi{sub 2}) and poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as interfacial layers (IFLs). Current-voltage data in the dark and AM1.5G light show that the TPDSi{sub 2}:TFB IFL yields MDMO-PPV:PCBM OPVs with substantially increased open-circuit voltage (V{sub oc}), power conversion efficiency, and thermal stability versus devices having no IFL or PEDOT:PSS. Using PEDOT:PSS and TPDSi{sub 2}:TFB together in the same cell greatly reduces dark current and produces the highest V{sub oc} (0.91 V) by combining the electron-blocking effects of both layers. ITO anode pre-treatment was investigated by X-ray photoelectron spectroscopy to understand why oxygen plasma, UV ozone, and solvent cleaning markedly affect cell response in combination with each IFL. O{sub 2} plasma and UV ozone treatment most effectively clean the ITO surface and are found most effective in preparing the surface for PEDOT:PSS deposition; UV ozone produces optimum solar cells with the TPDSi{sub 2}:TFB IFL. Solvent cleaning leaves significant residual carbon contamination on the ITO and is best followed by O{sub 2} plasma or UV ozone treatment. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    Science.gov (United States)

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.

  8. Analysis of InAs-Si heterojunction nanowire tunnel FETs: Extreme confinement vs. bulk

    Science.gov (United States)

    Carrillo-Nuñez, Hamilton; Luisier, Mathieu; Schenk, Andreas

    2015-11-01

    Extremely narrow and bulk-like p-type InAs-Si nanowire TFETs are studied using (i) a full-band and atomistic quantum transport simulator based on the sp3d5s∗ tight-binding model and (ii) a drift-diffusion TCAD tool. As (iii) option, a two-band model and the WKB approximation have been adapted to work in heterostructures through a careful choice of the imaginary dispersion. It is found that for ultra-scaled InAs-Si nanowire TFETs, the WKB approximation and the quantum transport results agree very well, suggesting that the former could be applied to larger hetero-TFET structures and considerably reduce the simulation time while keeping a high accuracy.

  9. Interfacial Engineering for Highly Efficient-Conjugated Polymer-Based Bulk Heterojunction Photovoltaic Devices

    Energy Technology Data Exchange (ETDEWEB)

    Alex Jen; David Ginger; Christine Luscombe; Hong Ma

    2012-04-02

    The aim of our proposal is to apply interface engineering approach to improve charge extraction, guide active layer morphology, improve materials compatibility, and ultimately allow the fabrication of high efficiency tandem cells. Specifically, we aim at developing: i. Interfacial engineering using small molecule self-assembled monolayers ii. Nanostructure engineering in OPVs using polymer brushes iii. Development of efficient light harvesting and high mobility materials for OPVs iv. Physical characterization of the nanostructured systems using electrostatic force microscopy, and conducting atomic force microscopy v. All-solution processed organic-based tandem cells using interfacial engineering to optimize the recombination layer currents vi. Theoretical modeling of charge transport in the active semiconducting layer The material development effort is guided by advanced computer modeling and surface/ interface engineering tools to allow us to obtain better understanding of the effect of electrode modifications on OPV performance for the investigation of more elaborate device structures. The materials and devices developed within this program represent a major conceptual advancement using an integrated approach combining rational molecular design, material, interface, process, and device engineering to achieve solar cells with high efficiency, stability, and the potential to be used for large-area roll-to-roll printing. This may create significant impact in lowering manufacturing cost of polymer solar cells for promoting clean renewable energy use and preventing the side effects from using fossil fuels to impact environment.

  10. Fabrication of Cu2O/γ-FeOOH heterojunction solar cells using electrodeposition

    Science.gov (United States)

    Vequizo, Junie Jhon M.; Ichimura, Masaya

    2014-04-01

    Cu2O/γ-FeOOH heterojunction solar cells were fabricated using galvanostatic-potentiostatic electrodeposition methods. The γ-FeOOH films showed n-type conductivity with a band gap of 2.2 eV. The electrodeposited Cu2O/γ-FeOOH heterojunction exhibited photovoltaic characteristics with a short-circuit current density of 0.95 mA/cm2 and open-circuit voltage of 0.11 V. Using core-level spectroscopy, it was demonstrated that the Cu2O/FeOOH heterostructure exhibited a type II junction with a valence band offset of 0.8 eV. The conduction band minimum of Cu2O was predicted to be higher than that of γ-FeOOH by 0.7 eV. This finding indicates that the γ-FeOOH material can be regarded as a suitable hetero-partner of other p-type absorbers.

  11. Effect of CdS modification on photoelectric properties of TiO2/PbS quantum dots bulk heterojunction

    Science.gov (United States)

    Shi, Xin; Xu, Jianping; Shi, Shaobo; Zhang, Xiaosong; Li, Shubin; Wang, Chang; Wang, Xueliang; Li, Linlin; Li, Lan

    2016-06-01

    TiO2/PbS(CdS) quantum dots (QDs) bulk heterojunction has been fabricated by successive ionic layer adsorption and reaction method via alternate deposition of PbS and CdS QDs. In comparison with TiO2/PbS heterojunction, the incident photon to current conversion efficiency was increased almost 50% in the visible region. Meantime, the short-circuit current and open-circuit voltage were enhanced 200% and 35% respectively. The influence mechanism of CdS is related to reduction of trap state density at TiO2/PbS interface and PbS QDs surface by the discussion of the dark current density-voltage curves, the transient photocurrent response curves and the electrochemical impedance spectra spectroscopy (EIS).

  12. Photoprecursor Approach Enables Preparation of Well-Performing Bulk-Heterojunction Layers Comprising a Highly Aggregating Molecular Semiconductor.

    Science.gov (United States)

    Suzuki, Mitsuharu; Yamaguchi, Yuji; Takahashi, Kohei; Takahira, Katsuya; Koganezawa, Tomoyuki; Masuo, Sadahiro; Nakayama, Ken-ichi; Yamada, Hiroko

    2016-04-01

    Active-layer morphology critically affects the performance of organic photovoltaic cells, and thus its optimization is a key toward the achievement of high-efficiency devices. However, the optimization of active-layer morphology is sometimes challenging because of the intrinsic properties of materials such as strong self-aggregating nature or low miscibility. This study postulates that the "photoprecursor approach" can serve as an effective means to prepare well-performing bulk-heterojunction (BHJ) layers containing highly aggregating molecular semiconductors. In the photoprecursor approach, a photoreactive precursor compound is solution-deposited and then converted in situ to a semiconducting material. This study employs 2,6-di(2-thienyl)anthracene (DTA) and [6,6]-phenyl-C71-butyric acid methyl ester as p- and n-type materials, respectively, in which DTA is generated by the photoprecursor approach from the corresponding α-diketone-type derivative DTADK. When only chloroform is used as a cast solvent, the photovoltaic performance of the resulting BHJ films is severely limited because of unfavorable film morphology. The addition of a high-boiling-point cosolvent, o-dichlorobenzene (o-DCB), to the cast solution leads to significant improvement such that the resulting active layers afford up to approximately 5 times higher power conversion efficiencies. The film structure is investigated by two-dimensional grazing-incident wide-angle X-ray diffraction, atomic force microscopy, and fluorescence microspectroscopy to demonstrate that the use of o-DCB leads to improvement in film crystallinity and increase in charge-carrier generation efficiency. The change in film structure is assumed to originate from dynamic molecular motion enabled by the existence of solvent during the in situ photoreaction. The unique features of the photoprecursor approach will be beneficial in extending the material and processing scopes for the development of organic thin-film devices. PMID

  13. In situ morphology studies of the mechanism for solution additive effects on the formation of bulk heterojunction films

    KAUST Repository

    Richter, Lee J.

    2014-09-29

    The most successful active film morphology in organic photovoltaics is the bulk heterojunction (BHJ). The performance of a BHJ arises from a complex interplay of the spatial organization of the segregated donor and acceptor phases and the local order/quality of the respective phases. These critical morphological features develop dynamically during film formation, and it has become common practice to control them by the introduction of processing additives. Here, in situ grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) studies of the development of order in BHJ films formed from the donor polymer poly(3-hexylthiophene) and acceptor phenyl-C61-butyric acid methyl ester under the influence of two common additives, 1,8-octanedithiol and 1-chloronaphthalene, are reported. By comparing optical aggregation to crystallization and using GISAXS to determine the number and nature of phases present during drying, two common mechanisms by which the additives increase P3HT crystallinity are identified. Additives accelerate the appearance of pre-crystalline nuclei by controlling solvent quality and allow for extended crystal growth by delaying the onset of PCBM-induced vitrification. The glass transition effects vary system-to-system and may be correlated to the number and composition of phases present during drying. Synchrotron X-ray scattering measurements of nanoscale structure evolution during the drying of polymer-fullerene photovoltaic films are described. Changes in the number and nature of phases, as well as the order within them, reveals the mechanisms by which formulation additives promote structural characteristics leading to higher power conversion efficiencies.

  14. Bifacial Si Heterojunction-Perovskite Organic-Inorganic Tandem to Produce Highly Efficient Solar Cell

    CERN Document Server

    Asadpour, Reza; Khan, M Ryyan; Alam, Muhammad A

    2015-01-01

    As single junction thin-film technologies, both Si heterojunction (HIT) and Perovskite based solar cells promise high efficiencies at low cost. One expects that a tandem cell design with these cells connected in series will improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics, however, we find that a traditional series connected tandem design suffers from low Jsc due to band-gap mismatch and current matching constraints. It requires careful thickness optimization of Perovskite to achieve any noticeable efficiency gain. Specifically, a traditional tandem cell with state-of-the-art HIT (24%) and Perovskite (20%) sub-cells provides only a modest tandem efficiency of ~25%. Instead, we demonstrate that a bifacial HIT/Perovskite tandem design decouples the optoelectronic constraints and provides an innovative path for extraordinary efficiencies. In the bifacial configuration, the same state-of the-art sub-cells achieve a normalized output of 33%, exceed...

  15. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    International Nuclear Information System (INIS)

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2-xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells

  16. Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells

    OpenAIRE

    Etgar, Lioz; Gao, Peng; Xue, Zhaosheng; Peng, Qin; Chandiran, Aravind Kumar; Liu, Bin; Nazeeruddin, Md. K.; Grätzel, Michael

    2012-01-01

    We report for the first time on a hole conductor-free mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell, produced by deposition of perovskite nanoparticles from a solution of CH3NH3I and PbI2 in γ-butyrolactone on a 400 nm thick film of TiO2 (anatase) nanosheets exposing (001) facets. A gold film was evaporated on top of the CH3NH3PbI3 as a back contact. Importantly, the CH3NH3PbI3 nanoparticles assume here simultaneous...

  17. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ambade, Swapnil B. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Mane, R.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Kale, S.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Sonawane, S.H. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Shaikh, Arif V. [Department of Electronic Science, AKI' s Poona College of Arts, Science and Commerce, Camp, Pune 411 001 (India); Han, Sung-Hwan [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of)]. E-mail: shhan@hanyang.ac.kr

    2006-12-15

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu{sub 2-x}Se phase was confirmed by XRD pattern and spherical grains of 30 {+-} 4 - 40 {+-} 4 nm in size aggregated over about 130 {+-} 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm{sup 2} light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  18. Nc-Si Thin Film Deposited at Low Temperature and Nc-Si Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    赵占霞; 崔容强; 孟凡英; 于化丛; 周之斌

    2004-01-01

    This paper reported some results about intrinsic nanocrystalline silicon thin films deposited by high frequency (HF) sputtering on p-type c-Si substrates at low temperature. Samples were examined by atomic force microscopy (AFM), X-ray diffraction (XRD), infrared absorption, and ellipsometry. XRD measurements show that this film has a new microstructure, which is different from the films deposited by other methods. The ellipsometry result gives that the optical band gap of the film is about 2.63 eV. In addition, the n-type nc-Si ∶ H/p-type c-Si heterojunction solar cell, which has open circuit voltage (Uoc) of 558 mV and short circuit current intensity (Isc) of 29 mA/cm2, was obtained based on the nanocrystalline silicon thin film. Irradiated under AM1.5, 100 mW/cm2 light intensity, the Uoc, Isc, and FF can keep stable for 10 h.

  19. Improved efficiency of electrodeposited p-CuO/n-Cu2O heterojunction solar cell

    Science.gov (United States)

    Jayathilaka, Charith; Kapaklis, Vassilios; Siripala, Withana; Jayanetti, Sumedha

    2015-06-01

    We report electrodeposition of n-type cuprous oxide (Cu2O) films on p-type CuO films electrodeposited on Ti substrates for forming p-CuO/n-Cu2O heterostructures. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed that the films had good structural quality, with substrates being well-covered by the films. The p-CuO/n-Cu2O heterojunctions exhibited good photovoltaic properties and diode characteristics. The surfaces of Cu2O films subject to ammonium sulfide treatment exhibited enhanced photocurrents. Under AM 1.5 illumniation, the obtained sulfur-treated and annealed Ti/p-CuO/n-Cu2O/Au solar cell structure yielded energy conversion efficiency of 0.64%, with Voc = 220 mV and Jsc = 6.8 mA cm-2.

  20. Looking at bulk-heterojunction organic photovoltaics from two viewpoints: morphology development and charge transfer

    Science.gov (United States)

    Van den Brande, Niko; Demir, Fatma; Geerlings, Paul; Van Mele, Bruno; Van Lier, Gregory; Van Assche, Guy

    2012-06-01

    In this paper, a combined experimental and theoretical study was performed on the P3HT:PCBM system used in organic photovoltaics. Fast-scanning differential chip calorimetry, an advanced thermal analysis technique, was used to simulate the thermal annealing used in the production of P3HT:PCBM solar cells to increase the degree of crystallinity, and thus efficiency. The main advantage of this technique for stuying the thermal annealing are the very high rates of heating and cooling that can be used, up to 106 K.s-1, permitting one to avoid crystallization during cooling. In parallel with the experimental study, the charge transfer between donor (P3HT) and acceptor (PCBM) at the interface is studied using density functional theory. The charge separation between donor and acceptor present for the ground state of the combined system, diminished when the first triplet was investigated. This was explained by the formation of a bridge state, formed after population by the LUMO with one electron. Such a molecular orbital can facilitate charge transfer.

  1. Explicit analytical modeling of the low frequency a-Si:H/c-Si heterojunction capacitance: Analysis and application to silicon heterojunction solar cells

    International Nuclear Information System (INIS)

    We develop a fully analytical model in order to describe the temperature dependence of the low frequency capacitance of heterojunctions between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). We demonstrate that the slope of the capacitance-temperature (C-T) curve is strongly enhanced if the c-Si surface is under strong inversion conditions compared to the usually assumed depletion layer capacitance. We have extended our analytical model to integrate a very thin undoped (i) a-Si:H layer at the interface and the finite thickness of the doped a-Si:H layer that are used in high efficiency solar cells for the passivation of interface defects and to limit short circuit current losses. Finally, using our calculations, we analyze experimental data on high efficiency silicon heterojunction solar cells. The transition from the strong inversion limited behavior to the depletion layer behavior is discussed in terms of band offsets, density of states in a-Si:H, and work function of the indium tin oxide (ITO) front electrode. In particular, it is evidenced that strong inversion conditions prevail at the c-Si surface at high temperatures down to 250 K, which can only be reproduced if the ITO work function is larger than 4.7 eV

  2. Explicit analytical modeling of the low frequency a-Si:H/c-Si heterojunction capacitance: Analysis and application to silicon heterojunction solar cells

    Science.gov (United States)

    Maslova, O.; Brézard-Oudot, A.; Gueunier-Farret, M.-E.; Alvarez, J.; Kleider, J.-P.

    2015-09-01

    We develop a fully analytical model in order to describe the temperature dependence of the low frequency capacitance of heterojunctions between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). We demonstrate that the slope of the capacitance-temperature (C-T) curve is strongly enhanced if the c-Si surface is under strong inversion conditions compared to the usually assumed depletion layer capacitance. We have extended our analytical model to integrate a very thin undoped (i) a-Si:H layer at the interface and the finite thickness of the doped a-Si:H layer that are used in high efficiency solar cells for the passivation of interface defects and to limit short circuit current losses. Finally, using our calculations, we analyze experimental data on high efficiency silicon heterojunction solar cells. The transition from the strong inversion limited behavior to the depletion layer behavior is discussed in terms of band offsets, density of states in a-Si:H, and work function of the indium tin oxide (ITO) front electrode. In particular, it is evidenced that strong inversion conditions prevail at the c-Si surface at high temperatures down to 250 K, which can only be reproduced if the ITO work function is larger than 4.7 eV.

  3. Explicit analytical modeling of the low frequency a-Si:H/c-Si heterojunction capacitance: Analysis and application to silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Maslova, O. [Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Miusskaya sq., 4, Moscow 125047 (Russian Federation); GeePs (Group of electrical engineering of Paris), CNRS UMR 8507, CentraleSupélec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France); Brézard-Oudot, A.; Gueunier-Farret, M.-E.; Alvarez, J.; Kleider, J.-P. [GeePs (Group of electrical engineering of Paris), CNRS UMR 8507, CentraleSupélec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France)

    2015-09-21

    We develop a fully analytical model in order to describe the temperature dependence of the low frequency capacitance of heterojunctions between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). We demonstrate that the slope of the capacitance-temperature (C-T) curve is strongly enhanced if the c-Si surface is under strong inversion conditions compared to the usually assumed depletion layer capacitance. We have extended our analytical model to integrate a very thin undoped (i) a-Si:H layer at the interface and the finite thickness of the doped a-Si:H layer that are used in high efficiency solar cells for the passivation of interface defects and to limit short circuit current losses. Finally, using our calculations, we analyze experimental data on high efficiency silicon heterojunction solar cells. The transition from the strong inversion limited behavior to the depletion layer behavior is discussed in terms of band offsets, density of states in a-Si:H, and work function of the indium tin oxide (ITO) front electrode. In particular, it is evidenced that strong inversion conditions prevail at the c-Si surface at high temperatures down to 250 K, which can only be reproduced if the ITO work function is larger than 4.7 eV.

  4. Additive to regulate the perovskite crystal film growth in planar heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xin; Sun, Po; Chen, Zhi-Kuan, E-mail: wlma@suda.edu.cn, E-mail: iamzkchen@njtech.edu.cn [Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), National Jiangsu Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816 (China); Wang, Weiwei; Ma, Wanli, E-mail: wlma@suda.edu.cn, E-mail: iamzkchen@njtech.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM) and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren' ai Road, Suzhou 215123 (China)

    2015-01-19

    We reported a planar heterojunction perovskite solar cell fabricated from MAPbI{sub 3−x}Cl{sub x} perovskite precursor solution containing 1-chloronaphthalene (CN) additive. The MAPbI{sub 3−x}Cl{sub x} perovskite films have been characterized by UV-vis, SEM, XRD, and steady-state photoluminescence (PL). UV-vis absorption spectra measurement shows that the absorbance of the film with CN additive is significantly higher than the pristine film and the absorption peak is red shift by 30 nm, indicating the perovskite film with additive possessing better crystal structures. In-situ XRD study of the perovskite films with additive demonstrated intense diffraction peaks from MAPbI{sub 3−x}Cl{sub x} perovskite crystal planes of (110), (220), and (330). SEM images of the films with additive indicated the films were more smooth and homogenous with fewer pin-holes and voids and better surface coverage than the pristine films. These results implied that the additive CN is beneficial to regulate the crystallization transformation kinetics of perovskite to form high quality crystal films. The steady-state PL measurement suggested that the films with additive contained less charge traps and defects. The planar heterojunction perovskite solar cells fabricated from perovskite precursor solution containing CN additive demonstrated 30% enhancement in performance compared to the devices with pristine films. The improvement in device efficiency is mainly attributed to the good crystal structures, more homogenous film morphology, and also fewer trap centers and defects in the films with the additive.

  5. Full Printable Processed Mesoscopic CH3NH3PbI3/TiO2 Heterojunction Solar Cells with Carbon Counter Electrode

    OpenAIRE

    Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Tongfa; Han, Hongwei

    2013-01-01

    A mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 heterojunction solar cell is developed with low-cost carbon counter electrode (CE) and full printable process. With carbon black/spheroidal graphite CE, this mesoscopic heterojunction solar cell presents high stability and power conversion efficiency of 6.64%, which is higher than that of the flaky graphite based device and comparable to the conventional Au version.

  6. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    inherent a-Si:H/c-Si band offset distribution with a low conduction band offset and a large valence band offset is disadvantageous for p-c-Si heterojunction solar cells if compared to their n-c-Si counterparts. A calculation of the saturation current densities of the cell's emitter, bulk and back contact demonstrates that the n-a-Si:H/p-c-Si emitter suffers from a low built-in potential. Modelling of the back contact based on the charge carrier transport equations shows that the insertion of an i-a-Si:H layer with a thickness d {>=} 3 nm (that is mandatory for a high surface passivation quality) leads to a series resistance that is critical for usage in a solar cell. The model mainly ascribes the high back contact resistance to the large valence band offset at the heterojunction. (orig.)

  7. Impact of incorporating sodium into polycrystalline p-type Cu2O for heterojunction solar cell applications

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2014-11-01

    The resistivity was controlled in the range of 103 to 10-2 Ω cm in polycrystalline p-type Cu2O sheets (incorporating sodium (Na)), which are suitable for Cu2O-based heterojunction solar cell applications. The Na-doped Cu2O sheets exhibited a hole concentration that ranged from 1013 to 1019 cm-3. In particular, a hole concentration of 1013-1016 cm-3 was obtained while maintaining a high Hall mobility above 100 cm2/V s, and, in addition, a degenerated semiconductor exhibiting metallic conduction was realized with a hole concentration above about 1 × 1019 cm-3. The mechanism associated with the Na doping can be explained by a copper vacancy produced due to charge compensation effects that result when a Na atom is incorporated at an interstitial site in the Cu2O lattice. For solar cell applications, the use of the Cu2O:Na sheet in a heterojunction solar cell successfully improved the obtained efficiency over that found in heterojunction solar cells fabricated using an undoped Cu2O sheet.

  8. Highly efficient hybrid solar cells based on an octithiophene-gaas heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, J.; Videlot, C.; El Kassmi, A.; Fages, F. [Laboratoire des Materiaux Moleculaires et des Biomateriaux, GCOM2 CNRS UMR 6114, Faculte des Sciences de Luminy, Case 901, 163 avenue de Luminy, F-13288 Marseille Cedex 09 (France); Guglielmetti, R. [Laboratoire de Chimie et Materiaux Organiques-Modelisation, GCOM2 CNRS UMR 6114, Faculte des Sciences de Luminy, Case 901, 163 avenue de Luminy, F-13288 Marseille Cedex 09 (France)

    2005-05-01

    We report a new type of hybrid heterojunction solar cell based on rod-like octithiophene (8T) as the organic p-type semiconductor and GaAs(111) as the inorganic n-type semiconductor. By using a semitransparent gold layer as the front contact deposited onto the 8T films, solar-energy conversion efficiencies of up to 4.2 % could be obtained. The reduction in the contact resistance at the Au/8T interface induced by iodine doping is found to be a very crucial factor for the high efficiency. Furthermore, we demonstrate that hybrid solar cells can be successfully used to investigate the photovoltaic properties of organic semiconductors in detail. By means of external quantum efficiency (EQE) measurements, the influence of film morphology on the photocurrent collection length in 8T films is studied. The results show that, in hybrid solar cells using highly ordered microcrystalline 8T films, an active contribution of the organic-layer semiconductor to the total photocurrent exists. A very large photocurrent collection length of up to 100 nm has been estimated from EQE measurements, indicating that exciton diffusion is very efficient in microcrystalline 8T. On the other hand, the use of nanocrystalline 8T leads to high photocurrent losses in the organic part of the hybrid solar cell. The strong influence of the film morphology on the photocurrent collection in 8T is attributed to a reduction in the exciton diffusion length due to a high trap density in nanocrystalline 8T films. Thus, our results reveal the importance of high crystalline order for obtaining efficient photocurrent collection in 8T films. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  9. Low temperature back-surface-field contacts deposited by hot-wire CVD for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain)], E-mail: delfina@eel.upc.edu; Voz, C.; Martin, I.; Orpella, A.; Alcubilla, R. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain); Villar, F.; Bertomeu, J.; Andreu, J. [CeRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain); Roca-i-Cabarrocas, P. [LPICM-Ecole Polytechnique, CNRS 91128 Palaiseau (France)

    2008-08-30

    The growing interest in using thinner wafers (< 200 {mu}m) requires the development of low temperature passivation strategies for the back contact of heterojunction solar cells. In this work, we investigate low temperature deposited back contacts based on boron-doped amorphous silicon films obtained by Hot-Wire CVD. The influence of the deposition parameters and the use of an intrinsic buffer layer have been considered. The microstructure of the deposited thin films has been comprehensively studied by Spectroscopic Ellipsometry in the UV-visible range. The effective recombination velocity at the back surface has been measured by the Quasi-Steady-State Photoconductance technique. Complete double-side heterojunction solar cells (1 cm{sup 2}) have been fabricated and characterized by External Quantum Efficiency and current-voltage measurements. Total-area conversion efficiencies up to 14.5% were achieved in a fully low temperature process (< 200 deg. C)

  10. Investigating the effect of carbon nanotube diameter and wall number in carbon nanotube/silicon heterojunction solar cells

    OpenAIRE

    Tom Grace; LePing Yu; Christopher Gibson; Daniel Tune; Huda Alturaif; Zeid Al Othman; Joseph Shapter

    2016-01-01

    Suspensions of single-walled, double-walled and multi-walled carbon nanotubes (CNTs) were generated in the same solvent at similar concentrations. Films were fabricated from these suspensions and used in carbon nanotube/silicon heterojunction solar cells and their properties were compared with reference to the number of walls in the nanotube samples. It was found that single-walled nanotubes generally produced more favorable results; however, the double and multi-walled nanotube films used in...

  11. Plasma-enhanced atomic-layer-deposited MoO{sub x} emitters for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Johannes; Schneider, Thomas; Sprafke, Alexander N. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Mews, Mathias; Korte, Lars [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Silicon-Photovoltaics, Berlin (Germany); Kaufmann, Kai [Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Germany); University of Applied Sciences, Hochschule Anhalt Koethen, Koethen (Germany); Wehrspohn, Ralf B. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Fraunhofer Institute for Mechanics of Materials IWM Halle, Halle (Germany)

    2015-09-15

    A method for the deposition of molybdenum oxide (MoO{sub x}) with high growth rates at temperatures below 200 C based on plasma-enhanced atomic layer deposition is presented. The stoichiometry of the over-stoichiometric MoO{sub x} films can be adjusted by the plasma parameters. First results of these layers acting as hole-selective contacts in silicon heterojunction solar cells are presented and discussed. (orig.)

  12. Fullerene mixing effect on carrier formation in bulk-hetero organic solar cell

    Science.gov (United States)

    Moritomo, Yutaka; Yasuda, Takeshi; Yonezawa, Kouhei; Sakurai, Takeaki; Takeichi, Yasuo; Suga, Hiroki; Takahashi, Yoshio; Inami, Nobuyuki; Mase, Kazuhiko; Ono, Kanta

    2015-03-01

    Organic solar cells (OSCs) with a bulk-heterojunction (BHJ) are promising energy conversion devices, because they are flexible and environmental-friendly, and can be fabricated by low-cost roll-to-roll process. Here, we systematically investigated the interrelations between photovoltaic properties and the domain morphology of the active layer in OSCs based on films of poly-(9,9-dioctylfluorene-co-bithiophene) (F8T2)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) blend annealed at various temperatures (Tan). The scanning transmission X-ray microscopy (STXM) revealed that fullerene mixing (ΦFullerene) in the polymer matrix decreases with increase in Tan while the domain size (L) is nearly independent of Tan. The TEM-S mapping image suggests that the polymer matrix consist of polymer clusters of several nm and fullerene. We found that the charge formation efficiency (ΦCF), internal quantum efficiency (ΦIQ), and power conversion efficiency (PCE) are dominantly determined by ΦFullerene. We interpreted these observations in terms of the polymer clusters within the polymer matrix.

  13. Interface Engineering of Organic Schottky Barrier Solar Cells and Its Application in Enhancing Performances of Planar Heterojunction Solar Cells

    Science.gov (United States)

    Jin, Fangming; Su, Zisheng; Chu, Bei; Cheng, Pengfei; Wang, Junbo; Zhao, Haifeng; Gao, Yuan; Yan, Xingwu; Li, Wenlian

    2016-01-01

    In this work, we describe the performance of organic Schottky barrier solar cells with the structure of ITO/molybdenum oxide (MoOx)/boron subphthalocyanine chloride (SubPc)/bathophenanthroline (BPhen)/Al. The SubPc-based Schottky barrier solar cells exhibited a short-circuit current density (Jsc) of 2.59 mA/cm2, an open-circuit voltage (Voc) of 1.06 V, and a power conversion efficiency (PCE) of 0.82% under simulated AM1.5 G solar illumination at 100 mW/cm2. Device performance was substantially enhanced by simply inserting thin organic hole transport material into the interface of MoOx and SubPc. The optimized devices realized a 180% increase in PCE of 2.30% and a peak Voc as high as 1.45 V was observed. We found that the improvement is due to the exciton and electron blocking effect of the interlayer and its thickness plays a vital role in balancing charge separation and suppressing quenching effect. Moreover, applying such interface engineering into MoOx/SubPc/C60 based planar heterojunction cells substantially enhanced the PCE of the device by 44%, from 3.48% to 5.03%. Finally, we also investigated the requirements of the interface material for Schottky barrier modification. PMID:27185635

  14. Heterojunction Diodes and Solar Cells Fabricated by Sputtering of GaAs on Single Crystalline Si

    Directory of Open Access Journals (Sweden)

    Santiago Silvestre

    2015-04-01

    Full Text Available This work reports fabrication details of heterojunction diodes and solar cells obtained by sputter deposition of amorphous GaAs on p-doped single crystalline Si. The effects of two additional process steps were investigated: A hydrofluoric acid (HF etching treatment of the Si substrate prior to the GaAs sputter deposition and a subsequent annealing treatment of the complete layered system. A transmission electron microscopy (TEM exploration of the interface reveals the formation of a few nanometer thick SiO2 interface layer and some crystallinity degree of the GaAs layer close to the interface. It was shown that an additional HF etching treatment of the Si substrate improves the short circuit current and degrades the open circuit voltage of the solar cells. Furthermore, an additional thermal annealing step was performed on some selected samples before and after the deposition of an indium tin oxide (ITO film on top of the a-GaAs layer. It was found that the occurrence of surface related defects is reduced in case of a heat treatment performed after the deposition of the ITO layer, which also results in a reduction of the dark saturation current density and resistive losses.

  15. Effects of Different Solvents on the Planar Hetero-junction Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Lin Shunquan

    2015-01-01

    Full Text Available The perovskite (CH3NH3PbI3 films on the planar hetero-junction perovskite solar cells (PHJ-PSCs are fabricated by “two-steps” process with the wet spin-coating method. The precursor (PbI2 solutions are compounded with 4 types of solvents: N-Methyl Pyrrolidone (NMP, γ-butyrolactone (GBL, Dimethyl Sulfoxide (DMSO and N, N-dimethylformamide (DMF. All the solutions have the same concentration. The influences of different precursor solvents to the micro-structures of CH3NH3PbI3 films and device performance are studied. Atomic force microscopy (AFM and scanning electron microscope (SEM are used to characterize the CH3NH3PbI3 films. The results indicate that the CH3NH3PbI3 film using DMF solvent possesses more rough morphology and thickest thickness. The monolithic PHJ-PSCs devices based on DMF solvent are tested under a standard one sun of simulated solar irradiation (AM1.5. The results show that the open-circuit voltage (Voc reaches 872mV, the short-circuit current (Jsc reaches 9.35mA/cm2, the filling factor(FF is 0.62 and the photo-current conversion efficiency (PCE is 5.05%. DMF is the best one among these 4 types of solvents for PHJ-PSCs.

  16. Numerical study of metal oxide hetero-junction solar cells with defects and interface states

    Science.gov (United States)

    Zhu, Le; Shao, Guosheng; Luo, J. K.

    2013-05-01

    Further to our previous work on ideal metal oxide (MO) hetero-junction solar cells, a systematic simulation has been carried out to investigate the effects of defects and interface states on the cells. Two structures of the window/absorber (WA) and window/absorber/voltage-enhancer (WAV) were modelled with defect concentration, defect energy level, interface state (ISt) density and ISt energy level as parameters. The simulation showed that the defects in the window layer and the voltage-enhancer layer have very limited effects on the performance of the cells, but those in the absorption layer have profound effects on the cell performance. The interface states at the W/A interface have a limited effect on the performance even for a density up to 1013 cm-2, while those at the A/V interface cause the solar cell to deteriorate severely even at a low density of lower than 1 × 1011 cm-2. It also showed that the back surface field (BSF) induced by band gap off-set in the WAV structure loses its function when defects with a modest concentration exist in the absorption layer and does not improve the open voltage at all.

  17. Silicon Heterojunction Solar Cells Using AlOx and Plasma-Immersion Ion Implantation

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2014-06-01

    Full Text Available Aluminum oxide (AlOx and plasma immersion ion implantation (PIII were studied in relation to passivated silicon heterojunction solar cells. When aluminum oxide (AlOx was deposited on the surface of a wafer; the electric field near the surface of wafer was enhanced; and the mobility of the carrier was improved; thus reducing carrier traps associated with dangling bonds. Using PIII enabled implanting nitrogen into the device to reduce dangling bonds and achieve the desired passivation effect. Depositing AlOx on the surface of a solar cell increased the short-circuit current density (Jsc; open-circuit voltage (Voc; and conversion efficiency from 27.84 mA/cm2; 0.52 V; and 8.97% to 29.34 mA/cm2; 0.54 V; and 9.68%; respectively. After controlling the depth and concentration of nitrogen by modulating the PIII energy; the ideal PIII condition was determined to be 2 keV and 10 min. As a result; a 15.42% conversion efficiency was thus achieved; and the Jsc; Voc; and fill factor were 37.78 mA/cm2; 0.55 V; and 0.742; respectively.

  18. Numerical study of metal oxide hetero-junction solar cells with defects and interface states

    International Nuclear Information System (INIS)

    Further to our previous work on ideal metal oxide (MO) hetero-junction solar cells, a systematic simulation has been carried out to investigate the effects of defects and interface states on the cells. Two structures of the window/absorber (WA) and window/absorber/voltage-enhancer (WAV) were modelled with defect concentration, defect energy level, interface state (ISt) density and ISt energy level as parameters. The simulation showed that the defects in the window layer and the voltage-enhancer layer have very limited effects on the performance of the cells, but those in the absorption layer have profound effects on the cell performance. The interface states at the W/A interface have a limited effect on the performance even for a density up to 1013 cm−2, while those at the A/V interface cause the solar cell to deteriorate severely even at a low density of lower than 1 × 1011 cm−2. It also showed that the back surface field (BSF) induced by band gap off-set in the WAV structure loses its function when defects with a modest concentration exist in the absorption layer and does not improve the open voltage at all. (paper)

  19. Nanostructured Organic Solar Cells

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Rubahn, Horst-Günter; Madsen, Morten

    Recent forecasts for alternative energy generation predict emerging importance of supporting state of art photovoltaic solar cells with their organic equivalents. Despite their significantly lower efficiency, number of application niches are suitable for organic solar cells. This work reveals...... the principles of bulk heterojunction organic solar cells fabrication as well as summarises major differences in physics of their operation....

  20. Semiconductor heterojunctions

    CERN Document Server

    Sharma, B L

    1974-01-01

    Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers.Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then

  1. Correlation of Interfacial Transportation Properties of CdS/CdTe Heterojunction and Performance of CdTe Polycrystalline Thin-Film Solar Cells

    OpenAIRE

    Guanggen Zeng; Jingquan Zhang; Wenwu Wang; Lianghuan Feng

    2015-01-01

    The light and dark output performances of CdS/CdTe solar cells made by close-spaced sublimation (CSS) were investigated to elucidate the transportation properties of carriers at CdS/CdTe heterojunction interface. It has been found that the interfacial transportation properties were relatively sensitive to variations of the characteristics of heterojunction due to the series resistance and shunting effects. For the high quality cell with 12.1% efficiency, narrow depletion region of ~1.1 micron...

  2. Opto-electronic properties of a TiO2/PS/mc-Si heterojunction based solar cell

    Science.gov (United States)

    Janene, N.; Ghrairi, N.; Allagui, A.; Alawadhi, H.; Khakani, M. A. El; Bessais, B.; Gaidi, M.

    2016-04-01

    In this work, we show the results of our investigation on the photoelectric properties of heterojunction solar cells based on Au/PS/mc-Si/Al and Au/TiO2/PS/mc-Si/Al structures. Porous silicon (PS) were prepared by an electrochemical etching process with different values of current density. The surface porosity was found to increase with the increase of current density. Pulsed laser deposition was used to deposit 80 nm TiO2 thin films. Surface morphology and structural properties of TiO2/PS were characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). An enhancement of the electrical properties of the TiO2/PS/mc-Si heterojunction was observed after coating with TiO2. As a consequence, the solar cell efficiencies increased from 1.4% for the uncoated PS/mc-Si structure to 5% for the TiO2 coated one. Impedance spectroscopy confirmed the passivation effect of TiO2 through the improvement of the elaborated cells' electron lifetime and the formation of a TiO2/PS/Au heterojunction with the appearance of a second semi-circle in the Nyquist plot.

  3. Hybrid nanostructure heterojunction solar cells fabricated using vertically aligned ZnO nanotubes grown on reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Yang Kaikun; Huang Liwei; Zou Lianfeng; Wang, Howard [Institute for Materials Research, Binghamton University, State University of New York, Binghamton, NY 13902 (United States); Xu Congkang, E-mail: wangh@binghamton.edu [Department of Mechanical Engineering, Binghamton University, State University of New York, Binghamton, NY 13902 (United States)

    2011-10-07

    Using reduced graphene oxide (rGO) films as the transparent conductive coating, inorganic/organic hybrid nanostructure heterojunction photovoltaic devices have been fabricated through hydrothermal synthesis of vertically aligned ZnO nanorods (ZnO-NRs) and nanotubes (ZnO-NTs) on rGO films followed by the spin casting of a poly(3-hexylthiophene) (P3HT) film. The data show that larger interfacial area in ZnO-NT/P3HT composites improves the exciton dissociation and the higher electrode conductance of rGO films helps the power output. This study offers an alternative to manufacturing nanostructure heterojunction solar cells at low temperatures using potentially low cost materials.

  4. Improving the performance of amorphous and crystalline silicon heterojunction solar cells by monitoring surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Schuettauf, J.W.A.; Van der Werf, C.H.M.; Kielen, I.M.; Van Sark, W.G.J.H.M.; Rath, J.K.; Schropp, R.E.I. [Utrecht University, Debye Institute for Nanomaterials Science, Nanophotonics, Physics of Devices, Princetonplein 5, 3584 CC Utrecht (Netherlands)

    2012-09-15

    The influence of thermal annealing on the crystalline silicon surface passivating properties of selected amorphous silicon containing layer stacks (including intrinsic and doped films), as well as the correlation with silicon heterojunction solar cell performance has been investigated. All samples have been isochronally annealed for 1 h in an N{sub 2} ambient at temperatures between 150C and 300C in incremental steps of 15C. For intrinsic films and intrinsic/n-type stacks, an improvement in passivation quality is observed up to 255C and 270C, respectively, and a deterioration at higher temperatures. For intrinsic/n-type a-Si:H layer stacks, a maximum minority carrier lifetime of 13.3 ms at an injection level of 10{sup 15} cm{sup -3} has been measured. In contrast, for intrinsic/p-type a-Si:H layer stacks, a deterioration in passivation is observed upon annealing over the whole temperature range. Comparing the lifetime values and trends for the different layer stacks to the performance of the corresponding cells, it is inferred that the intrinsic/p-layer stack is limiting device performance. Furthermore, thermal annealing of p-type layers should be avoided entirely. We therefore propose an adapted processing sequence, leading to a substantial improvement in efficiency to 16.7%, well above the efficiency of 15.8% obtained with the 'standard' processing sequence.

  5. Laser Induced Forward Transfer for front contact improvement in silicon heterojunction solar cells

    Science.gov (United States)

    Colina, M.; Morales-Vilches, A.; Voz, C.; Martín, I.; Ortega, P.; Orpella, A.; López, G.; Alcubilla, R.

    2015-05-01

    In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms occurs when a sequence of laser pulses impinging onto the doped layer propels the material toward the substrate. The laser irradiation not only transfers the doping material but also produces a local heating that promotes its diffusion into the substrate. The laser employed was a 1064 nm, lamp-pumped system, working at pulse durations of 100 and 400 ns. In order to obtain a good electrical performance a comprehensive optimization of the applied laser fluency and number of pulses was carried out. Subsequently, arrays of n + p local junctions were created by LIFT and the resulting J-V curves demonstrated the formation of good quality n+ regions. These structures were finally incorporated to enhance the front contact in conventional silicon heterojunction solar cells leading to an improvement of conversion efficiency.

  6. Pyramidal texturing of silicon surface via inorganic-organic hybrid alkaline liquor for heterojunction solar cells

    Science.gov (United States)

    Wang, Fengyou; Zhang, Xiaodan; Wang, Liguo; Jiang, Yuanjian; Wei, Changchun; Zhao, Ying

    2015-10-01

    We demonstrate a new class of silicon texturing approach based on inorganic (sodium hydroxide, NaOH) and organic (tetramethylammonium hydroxide, TMAH) alkaline liquor etching processes for photovoltaic applications. The first stage of inorganic alkaline etching textures the silicon surface rapidly with large pyramids and reduces the cost. The subsequent organic alkaline second-etching improves the coverage of small pyramids on the silicon surface and strip off the metallic contaminants produced by the first etching step. In addition, it could smoothen the surface of the pyramids to yield good morphology. In this study, the texturing duration of both etching steps was controlled to optimize the optical and electrical properties as well as the surface morphology and passivation characteristics of the silicon substrates. Compared with traditional inorganic NaOH texturing, this hybrid process yields smoother (111) facets of the pyramids, fewer residual Na+ ions on the silicon surface, and a shorter processing period. It also offers the advantage of lower cost compared with the organic texturing method based on the use of only TMAH. We applied this hybrid texturing process to fabricate silicon heterojunction solar cells, which showed a remarkable improvement compared with the cells based on traditional alkaline texturing processes.

  7. Temperature dependent competition between different recombination channels in organic heterojunction solar cells

    International Nuclear Information System (INIS)

    A modification of the Shockley–Queisser theory for organic heterojunctions is presented with a special focus on constellations, where a linear extrapolation of the temperature dependence of the open circuit voltage results in the optical gap of the absorber rather than in the intermolecular charge transfer (CT) gap. We demonstrate that, depending on the electronic coupling strength between donor and acceptor molecules, either singlet or CT recombination is dominant in different temperature regimes. The different regimes are separated by a transition temperature that is usually well above room temperature (RT). However, in the case of small energy level offset and weak electronic coupling, it can be around 300 K or even below. We point out that a linear extrapolation of the open circuit voltage V oc towards 0 K for measured temperatures larger than the transition temperature results in a photovoltaic gap that is close to the optical gap, whereas for values below the transition temperature the CT gap will be extracted. We show that for α-sexithiophene (6T)/diindenoperylene (DIP) solar cells heating the substrate during 6T deposition leads to a molecular configuration at the interface where the coupling between donor and acceptor molecules is strongly reduced. This leads to a transition temperature well below RT which is confirmed by temperature dependent electroluminescence measurements. By comparing the temperature dependent spectra of high temperature and RT grown 6T/DIP solar cells to the spectra of the individual materials, the different contributions from the CT gap and the optical gap are separated. (paper)

  8. Harnessing light energy with a planar transparent hybrid of graphene/single wall carbon nanotube/n-type silicon heterojunction solar cell

    DEFF Research Database (Denmark)

    Chen, Leifeng; Yu, Hua; Zhong, Jiasong;

    2015-01-01

    The photovoltaic conversion efficiency of a solar cell fabricated by a simple electrophoretic method with a planar transparent hybrid of graphenes (GPs) and single wall carbon nanotubes (SCNTs)/n-type silicon heterojunction was significantly increased compared to GPs/n-Si and SCNTs/n-Si solar cel...

  9. Built-in voltage of organic bulk heterojuction p-i-n solar cells measured by electroabsorption spectroscopy

    Directory of Open Access Journals (Sweden)

    E. Siebert-Henze

    2014-04-01

    Full Text Available We investigate the influence of the built-in voltage on the performance of organic bulk heterojuction solar cells that are based on a p-i-n structure. Electrical doping in the hole and the electron transport layer allows to tune their work function and hence to adjust the built-in voltage: Changing the doping concentration from 0.5 to 32 wt% induces a shift of the work function towards the transport levels and increases the built-in voltage. To determine the built-in voltage, we use electroabsorption spectroscopy which is based on an evaluation of the spectra caused by a change in absorption due to an electric field (Stark effect. For a model system with a bulk heterojunction of BF-DPB and C60, we show that higher doping concentrations in both the electron and the hole transport layer increase the built-in voltage, leading to an enhanced short circuit current and solar cell performance.

  10. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-07-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials.

  11. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-01-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials. PMID:27411487

  12. A composite light-harvesting layer from photoactive polymer and halide perovskite for planar heterojunction solar cells.

    Science.gov (United States)

    Wang, Heming; Rahaq, Yaqub; Kumar, Vikas

    2016-01-01

    A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials. PMID:27411487

  13. High-Efficiency Cu2O-Based Heterojunction Solar Cells Fabricated Using a Ga2O3 Thin Film as N-Type Layer

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2013-04-01

    High-efficiency heterojunction solar cells consisting of a nondoped Ga2O3 thin film as an n-type semiconductor layer and a p-type Cu2O sheet as the active layer as well as the substrate, prepared by thermally oxidizing a Cu sheet, are demonstrated. The use of an n-type Ga2O3 thin film can greatly improve the performance of n-Ga2O3/p-Cu2O heterojunction solar cells. The highest efficiency of 5.38% was obtained in an Al-doped ZnO/Ga2O3/Cu2O heterojunction solar cell fabricated with an n-Ga2O3 thin-film layer prepared at room temperature with a thickness of 75 nm by a pulsed laser deposition method.

  14. Titanium dioxide/zinc indium sulfide hetero-junction: An efficient photoanode for the dye-sensitized solar cell

    Science.gov (United States)

    Hou, Wenjing; Xiao, Yaoming; Han, Gaoyi; Zhang, Ying; Chang, Yunzhen

    2016-10-01

    A facile strategy is developed for the fabrication of titanium dioxide/zinc indium sulfide (TiO2/ZnIn2S4) hetero-junction photoanode with an adjustable ZnIn2S4 doping content and application in the dye-sensitized solar cell (DSSC). Comparing to the pure TiO2, TiO2/ZnIn2S4 hetero-junction materials demonstrate an enhanced light utilizing efficiency, a reduced recombination rate of electron-hole pairs, and an accelerated migration process of photoinduced electrons. Due to above merits, DSSC based on TiO2/ZnIn2S4 hetero-junction photoanode achieves a greatly enhanced short-circuit current density, leading to an improved photoelectric conversion efficiency of 8.09% under full sunlight illumination (100 mW cm-2, AM 1.5 G), which is almost 14.43% higher than that of the pure TiO2-based DSSC (7.07%).

  15. Low temperature characteristic of ITO/SiO x /c-Si heterojunction solar cell

    Science.gov (United States)

    Du, H. W.; Yang, J.; Li, Y.; Gao, M.; Chen, S. M.; Yu, Z. S.; Xu, F.; Ma, Z. Q.

    2015-09-01

    Based on the temperature-dependent measurements and the numerical calculation, the temperature response of the photovoltaic parameters for a ITO/SiO x /c-Si heterojunction solar cell have been investigated in the ascending sorting of 10-300 K. Under unique energy concentrated photon irradiation with the wavelength of 405 nm and power density of 667 mW cm-2, it was found that the short-circuit current (I SC) was nonlinearly increased and the open-circuit voltage (V OC) decreased with temperature. The good passivation of the ITO/c-Si interface by a concomitant SiO x buffer layer leads to the rare recombination of carriers in the intermediate region. The inversion layer model indicated that the band gap of c-silicon was narrowed and the Fermi level of n-type silicon (E\\text{F}n ) tended to that of the intrinsic Fermi level (E\\text{F}i ) (in the middle of band gap) with the increase of the temperature, which lessened the built-in voltage (V D) and thus the V OC. However, the reduction by 90% of V OC is attributed to the shift of E\\text{F}n in c-silicon rather than the energy band narrowing. Through the analysis of the current-voltage relationship and the data fitting, we infer that the series resistance (R s) is not responsible for the increase of I SC, but the absorption coefficient and the depletion-width of c-silicon are the causes of the enhancing I SC. Mostly, the interaction of the photon-generated excess ‘cold hole’ and the acoustic phonon in n-Si would influence the variation of I ph or I SC with temperature.

  16. Electrochemical Deposition of CuxSnySzO Thin Films and Their Application for Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Yuki Nakashima

    2012-01-01

    Full Text Available CuxSnySzO (CTSO thin films were deposited from an aqueous solution containing CuSO4, SnSO4, and Na2S2O3 by electrochemical techniques. The deposited films were characterized by Auger electron spectroscopy, X-ray diffraction, and optical transmission spectroscopy. The photoelectrochemical measurement showed that the films have p-type conduction and photosensitivity. ZnO/CTSO heterojunction solar cells were fabricated. Rectification properties were observed, and the cell showed an efficiency of 4.9×10−3% under AM1.5 illumination.

  17. 19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact

    OpenAIRE

    Yin, Xingtian; Battaglia, Corsin; Lin, Yongjing; Chen, Kevin; Hettick, Mark; Zheng, Maxwell; Chen, Cheng-Ying; Kiriya, Daisuke; Javey, Ali

    2014-01-01

    We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO2 deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-w...

  18. Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

    Science.gov (United States)

    Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

    2016-07-01

    The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300 °C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline silicon wafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450 °C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450 °C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltage of over 710 mV and an efficiency of over 19%.

  19. Efficient silicon heterojunction solar cells based on p- and n-type substrates processed at temperatures < 220 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Maydell, K.v.; Conrad, E.; Schmidt, M. [Hahn-Meitner-Institut, Berlin (Germany)

    2006-07-01

    We present the optimization and characterization of heterojunction solar cells consisting of an amorphous silicon emitter, a single crystalline absorber and an amorphous silicon rear side which causes the formation of a back surface field (a-Si:H/c-Si/a-Si:H). The solar cells were processed at temperatures <220 deg C. An optimum of the gas phase doping concentration of the a-Si:H layers was found. For high gas phase doping concentrations, recombination via defects located at or nearby the interface leads to a decrease in solar cell efficiency. We achieved efficiencies >17% on p-type c-Si absorbers and >17.5% on n-type absorbers. In contrast to the approach of Sanyo, no additional intrinsic a-Si:H layers between the substrate and the doped a-Si:H layers were inserted. (Author)

  20. Effect of annealing on silicon heterojunction solar cells with textured ZnO:Al as transparent conductive oxide

    Directory of Open Access Journals (Sweden)

    Roca i Cabarrocas P.

    2012-07-01

    Full Text Available We report on silicon heterojunction solar cells using textured aluminum doped zinc oxide (ZnO:Al as a transparent conductive oxide (TCO instead of flat indium tin oxide. Double side silicon heterojunction solar cell were fabricated by radio frequency plasma enhanced chemical vapor deposition on high life time N-type float zone crystalline silicon wafers. On both sides of these cells we have deposited by radio frequency magnetron sputtering ZnO:Al layers of thickness ranging from 800 nm to 1400 nm. These TCO layers were then textured by dipping the samples in a 0.5% hydrochloric acid. External quantum efficiency as well as I-V under 1 sun illumination measurements showed an increase of the current for the cells using textured ZnO:Al. The cells were then annealed at 150 °C, 175 °C and 200 °C during 30 min in ambient atmosphere and characterized at each annealing step. The results show that annealing has no impact on the open circuit voltage of the devices but that up to a 175 °C it enhances their short circuit current, consistent with an overall enhancement of their spectral response. Our results suggest that ZnO:Al is a promising material to increase the short circuit current (Jsc while avoiding texturing the c-Si substrate.

  1. Bulk- and layer-heterojunction phototransistors based on poly [2-methoxy-5-(2′-ethylhexyloxy-p-phenylenevinylene)] and PbS quantum dot hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xiaoxian; Zhang, Yating, E-mail: yating@tju.edu.cn; Wang, Ran; Cao, Mingxuan; Che, Yongli; Wang, Jianlong; Wang, Haiyan; Jin, Lufan; Ding, Xin; Zhang, Guizhong; Yao, Jianquan [Institute of Laser and Opto-Electronics, College of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Opto-Electronics Information Technology (Tianjin University), Ministry of Education, Tianjin 300072 (China); Dai, Haitao [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China)

    2015-06-22

    The responsivity (R) of a thin film photodetector is proportional to the product of its photo-induced carrier density (n) and mobility (μ). However, when choosing between layer heterojunction (LH) and bulk heterojunction (BH) field-effect phototransistors (FEpTs), it is still unclear which of the two device structures is more conducive to photodetection. A comparison study is performed on the two structures based on polymer and PbS quantum dot hybrids. Both devices exhibit ambipolar behavior, with μ{sub E} ≈ μ{sub H} = 3.7 cm{sup 2} V{sup −1} s{sup −1} for BH-FEpTs and μ{sub H} = 36 cm{sup 2} V{sup −1} s{sup −1} and μ{sub E} = 52 cm{sup 2} V{sup −1} s{sup −1} for LH-FEpTs. Because of the improvements in μ and the channel order degree (α), the responsivity of LH-FEpTs is as high as 10{sup 1 }A/W, which is as much as two orders of magnitude higher than that of BH-FEpTs (10{sup −1}A/W) under the same conditions. Although the large area of the BH improves both the exciton separation degree (β) and n in the BH-FEpT, the lack of an effective transport mechanism becomes the main constraint on high device responsivity. Therefore, LH-FEpTs are better candidates for use as photo detectors, and a “three-high” principle of high α, β, and μ is found to be required for high responsivity.

  2. An Organic D-π-A Dye for Record Efficiency Solid-State Sensitized Heterojunction Solar Cells

    KAUST Repository

    Cai, Ning

    2011-04-13

    The high molar absorption coefficient organic D-π-A dye C220 exhibits more than 6% certified electric power conversion efficiency at AM 1.5G solar irradiation (100 mW cm-2) in a solid-state dye-sensitized solar cell using 2,2′,7,7′-tetrakis(N,N-dimethoxyphenylamine)-9,9′- spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. This contributes to a new record (6.08% by NREL) for this type of sensitized heterojunction photovoltaic device. Efficient charge generation is proved by incident photon-to-current conversion efficiency spectra. Transient photovoltage and photocurrent decay measurements showed that the enhanced performance achieved with C220 partially stems from the high charge collection efficiency over a wide potential range. © 2011 American Chemical Society.

  3. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.

    2014-04-14

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  4. Role of the buffer layer in the active junction in amorphous-crystalline silicon heterojunction solar cells

    Science.gov (United States)

    Pallarès, J.; Schropp, R. E. I.

    2000-07-01

    We fabricated pn and pin a-SiC:H/c-Si heterojunction solar cells following two different processes. In the first approach, wafers were subjected to an extra atomic hydrogen (produced by hot wire chemical vapor deposition) prior to the deposition of the amorphous layer. A reduction in the open-circuit voltage was observed for the passivated cells due to their higher leakage current. In the second process, pin solar cells with two different quality intrinsic a-Si:H buffer layers were fabricated using plasma enhanced chemical vapor deposition. The cells with a device quality buffer layer (deposited at higher temperature) showed better performance than those with a buffer layer with high hydrogen content and higher defect density (deposited at lower temperatures).

  5. Construction of flexible photoelectrochemical solar cells based on ordered nanostructural BiOI/Bi2S3 heterojunction films.

    Science.gov (United States)

    Fang, Mingqing; Jia, Huimin; He, Weiwei; Lei, Yan; Zhang, Lizhi; Zheng, Zhi

    2015-05-28

    Ordered 2D nanostructural BiOI nanoflake arrays decorated with Bi2S3 nanospheres have been designed and in situ fabricated for the first time, to form BiOI/Bi2S3 bulk heterojunctions through a soft chemical route. A modified successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate BiOI nanoflake arrays on flexible ITO/PET substrates at room temperature. The degree of transformation of BiOI to Bi2S3 was controlled through the adjustment of exposure time of the BiOI/ITO substrate to thioacetamide (TAA) aqueous solution. The morphologies of BiOI, BiOI/Bi2S3 heterojunctions and Bi2S3 films were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) patterns, and high resolution transmission electron microscopy (HRTEM). The presence of Bi2S3 was further validated through Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Especially, photoelectrochemical measurements demonstrated that such a Bi2S3 decorated BiOI photoanode based cell exhibits significant augments of short-circuit current density (Jsc) and incident photon-to-current conversion efficiency (IPCE, 3 times higher than the pure BiOI photoanode), attributable to the stronger photo-absorption and better photogenerated charge carrier separation and transport efficiency. The surface photovoltage (SPV) measurements further confirmed the importance of BiOI/Bi2S3 heterojunctions in such PEC cells. This solution-based process directly on flexible ITO offers the promise for low-cost, large-area, roll-to-roll application of the manufacturing of the third generation thin-film photovoltaic devices. PMID:25941684

  6. Improvement of the SiOx passivation layer for high-efficiency Si/PEDOT:PSS heterojunction solar cells.

    Science.gov (United States)

    Sheng, Jiang; Fan, Ke; Wang, Dan; Han, Can; Fang, Junfeng; Gao, Pingqi; Ye, Jichun

    2014-09-24

    Interfacial properties currently hinder the performance of Si/organic heterojunction solar cells for an alternative to high-efficiency and low-cost photovoltaics. Here, we present a simple and repeatable wet oxidation method for developing the surface passivation layer, SiOx, on the Si surface for the fabrication of high-efficiency Si/poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) heterojunction solar cells. The uniform and dense SiOx thin layer introduced by the oxidizing aqueous solution of H2O2 or HNO3 provided the better surface passivation and stronger wettability of the Si surface, compared to those in the native oxide case. These two types of progress helped create a lower defect density at the Si/PEDOT:PSS interface and thus a high-quality p-n junction with a lower interface recombination velocity. As a result, the HNO3-oxidized device displayed better performance with a power conversion efficiency (PCE) of 11%, representing a 28.96% enhancement from the PCE of 8.53% in the native oxide case. The effects on the performance of the Si/PEDOT:PSS hybrid solar cells of the wet oxidation treatment procedure, including the differences in surface roughness and wettability of the Si substrate, the quality and thickness of the SiOx, etc., were explored extensively. Such a simple and controllable oxidizing treatment could be an effective way to promote the interfacial properties that are an important cornerstone for more efficient Si/organic hybrid solar cells.

  7. Current enhancement of aluminum doped ZnO/n-Si isotype heterojunction solar cells by embedding silver nanoparticles.

    Science.gov (United States)

    Yun, Juhyung; Kim, Joondong; Kojori, Hossein Shokri; Kim, Sung Jim; Tong, Chong; Anderson, Wayne A

    2013-08-01

    To improve Plasmonic energy harvesting, the Al doped ZnO (AZO) and Si heterojunction was studied for plasmonic photovoltaic applications. Silver nanoparticles (Ag NPs) were embedded in AZO, resulting in direct energy absoption from Ag NPs, positioned close to the junction. This structure has a benefit of avoiding highly doped lossy layers of conventional solar cell structures. Al doped ZnO (AZO) was deposited on n-Si substrate by dual beam sputtering method to fabricate AZO/Si heterojunction solar cells. AZO provides a transparent current spreading effect and rectifying junction with n type silicon (Si). Silver nanoparticles (Ag NPs) were embedded in AZO film (240-270 nm thick) with a sandwich-like structure. The position of Ag NPs in the AZO film was controlled to be located at 10, 20 and 40 nm distance from the Si absorber layer. Fabricated solar cells show improved performance in terms of the short circuit current (J(sc)) and the quantum efficiency (QE). Finite difference time domain (FDTD) simulations were carried out to investigate the QE enhancement and optimize photocurrent gain under an AM1.5G solar spectrum. In calculation, absorption enhancement is maximized when Ag NPs are located close to the Si layer in the range of 10-40 nm. Experimentally, 20 nm distance of Ag NPs from the Si showed the best performance with 0.36 V of open circuit voltage (V(oc)), 28.3 mA/cm2 of J(sc) and 5.91% of coversion efficiency. The QE showed 15% of enhancement around lambda = 435 nm and 5-10% of enhancement within lambda = 600-1000 nm. PMID:23882792

  8. Multi-length-scale morphologies in PCPDTBT/PCBM bulk-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yu. [Department of Polymer Science and Engineering, University of Massachusetts-Amherst, Amherst, MA 01003 (United States); Wang, Cheng [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Russell, Thomas P. [Department of Polymer Science and Engineering, University of Massachusetts-Amherst, Amherst, MA 01003 (United States); WPI Advanced Institute of Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2012-06-15

    Additives are known to improve the performance of organic photovoltaic devices based on mixtures of a low bandgap polymer, poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). The evolution of the morphology during the evaporation of the mixed solvent, which comprises additive and chlorobenzene (CB), is investigated by in-situ grazing incidence X-ray scattering, providing insight into the key role the additive plays in developing a multi-length-scale morphology. Provided the additive has a higher vapor pressure and a selective solubility for PCBM, as the host solvent (CB) evaporates, the mixture of the primary solvent and additive becomes less favorable for the PCPDTBT, while completely solubilizing the PCBM. During this process, the PCPDTBT first crystallizes into fibrils and then the PCBM, along with the remaining PCPDTBT, is deposited, forming a phase-separated morphology comprising domains of pure, crystalline PCPDTBT fibrils and another domain that is a PCBM-rich mixture with amorphous PCPDTBT. X-ray/neutron scattering and diffraction methods, in combination with UV-vis absorption spectroscopy and transmission electron microscopy, are used to determine the crystallinity and phase separation of the resultant PCPDTBT/PCBM thin films processed with or without additives. Additional thermal annealing is carried out and found to change the packing of the PCPDTBT. The two factors, degree of crystallinity and degree of phase separation, control the multi-length-scale morphology of the thin films and significantly influence device performance. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Organic bulk heterojunction solar cells: from single cell towards flexible photovoltaic module.

    OpenAIRE

    Aernouts, Tom

    2006-01-01

    Verschillende geo-politieke conflicten, maar ook vele natuurrampen maken duidelijk dat er zowel economisch als ecologisch een grote nood is om w erk te maken van duurzamere methodes voor de opwekking van energie. Er z ijn al heel wat technologieën beschikbaar om dit te verwezenlijken en no g andere worden verder ontwikkeld of onderzocht. De verwachtingen zijn d at fotovoltaische omzetting van het overvloedig beschikbare zonlicht in onmiddellijk bruikbare electriciteit binnen enkele tientallen...

  10. Synthesis and Characterization of Quinoxaline-Based Low-Bandgap Copolymers for Bulk Heterojunction Solar Cells

    Science.gov (United States)

    Lee, Yoonkyoo; Jo, Won Ho

    2011-03-01

    A series of low-bandgap alternating copolymers consisting of quinoxaline derivatives and electron-donating carbazole or fluorene were synthesized via the Suzuki coupling reaction. For the purpose to improve the molecular packing of polymer chains and to enhance the charge carrier mobility in the packing direction, a new quinoxaline derivative, 5,8-dithien-2-yl-dibenzophenazine which has perfectly planar polycyclic structure, was synthesized and introduced as a new building block for alternating copolymers instead of frequently-used 5,8-dithien-2-yl-2,3-diphenylquinoxaline. The use of planar quinoxaline derivative exhibited better optical, electrochemical, and structural properties of the resulting copolymers as compared to those of polymers with less planar quinoxaline derivatives. Charge transport and photovoltaic properties of these two classes of copolymers are compared and discussed.

  11. Solution-Processed Bulk Heterojunction Solar Cells with Silyl End-Capped Sexithiophene

    Directory of Open Access Journals (Sweden)

    Jung Hei Choi

    2013-01-01

    Full Text Available We fabricated solution-processed organic photovoltaic cells (OPVs using substituted two sexithiophenes, a,w-bis(dimethyl-n-octylsilylsexithiophene (DSi-6T and a,w-dihexylsexithiophene (DH-6T, as electron donors, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM as an electron acceptor. Solution-processed OPVs using DH-6T and DSi-6T showed good photovoltaic properties in spite of their poor solubility. The best performance was observed on DSi-6T : PCBM 1 : 5 (w/w blend cell with an open circuit voltage (Voc of 0.63 V, short circuit current density (Jsc of 1.34 mA/cm2, fill factor (FF of 55%, and power conversion efficiency of 0.44% under AM 1.5 G illumination. Although DH-6T has higher hole mobility than DSi-6T, the DSi-6T : PCBM blend cell showed higher hole mobility than DH-6T : PCBM cell. Therefore, DSi-6T cell showed higher device performance than DH-6T cell due to its silyl substitutions, which lead to the increase of the solubility. The incorporation of solution-processed TiO2 interfacial layer in the DSi-6T : PCBM devices significantly enhances FF due to the reduced charge recombination near active layer/Al interface.

  12. Direct and charge transfer state mediated photogeneration in polymer-fullerene bulk heterojunction solar cells

    Science.gov (United States)

    Mingebach, M.; Walter, S.; Dyakonov, V.; Deibel, C.

    2012-05-01

    We investigated photogeneration yield and recombination dynamics in blends of poly(3-hexyl thiophene) (P3HT) and poly[2-methoxy-5 -(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) with [6,6]-phenyl-C61butyric acid methyl ester (PC61BM) by means of temperature dependent time delayed collection field measurements. In MDMO-PPV:PC61BM, we find a strongly field dependent polaron pair dissociation which can be attributed to geminate recombination in the device. Our findings are in good agreement with field dependent photoluminescence measurements published before, supporting a scenario of polaron pair dissociation via an intermediate charge transfer state. In contrast, polaron pair dissociation in P3HT:PC61BM shows only a very weak field dependence, indicating an almost field independent polaron pair dissociation or a direct photogeneration. Furthermore, we found Langevin recombination for MDMO-PPV:PC61BM and strongly reduced Langevin recombination for P3HT:PC61BM.

  13. High-Permittivity Conjugated Polyelectrolyte Interlayers for High-Performance Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Kesters, Jurgen; Govaerts, Sanne; Pirotte, Geert; Drijkoningen, Jeroen; Chevrier, Michèle; Van den Brande, Niko; Liu, Xianjie; Fahlman, Mats; Van Mele, Bruno; Lutsen, Laurence; Vanderzande, Dirk; Manca, Jean; Clément, Sébastien; Von Hauff, Elizabeth; Maes, Wouter

    2016-03-16

    Conjugated polyelectrolyte (CPE) interfacial layers present a powerful way to boost the I-V characteristics of organic photovoltaics. Nevertheless, clear guidelines with respect to the structure of high-performance interlayers are still lacking. In this work, impedance spectroscopy is applied to probe the dielectric permittivity of a series of polythiophene-based CPEs. The presence of ionic pendant groups grants the formation of a capacitive double layer, boosting the charge extraction and device efficiency. A counteracting effect is the diminishing affinity with the underlying photoactive layer. To balance these two effects, we found copolymer structures containing nonionic side chains to be beneficial. PMID:26927416

  14. Measuring the complete cross-cell carrier mobility distributions in bulk heterojunction solar cells

    Science.gov (United States)

    Seifter, Jason; Sun, Yanming; Choi, Hyosung; Lee, Byoung Hoon; Heeger, Alan

    2015-03-01

    Carbon nanotube-enabled, vertical, organic field effect transistors (CN-VFETs) based on the small molecule dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) have demonstrated high current, low-power operation suitable for driving active matix organic light emitting diode (AMOLED) displays. This performance is achieved without the need for costly high-resolution patterning, despite the low mobility of the organic semiconductor, by employing sub-micron channel widths, defined in the vertical devices by the thickness of the semiconducting layer. Replacing the thermally evaporated small molecule semiconductor with a solution-processed polymer would possibly further simplify the fabrication process and reduce manufacturing cost. Here we investigate several polymer systems as wide bandgap semiconducting channel layers for potentially air stable and transparent CN-VFETs. The field effect mobility and optical transparency of the polymer layers are determined, and the performance and air stability of CN-VFET devices are measured. A. S. gratefully acknowledges support from the National Science Foundation under DMR-1156737.

  15. Electrical characterization of all-sputtered CdS/CuInSe sub 2 solar cell heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Santamaria, J.; Martil, I.; Iborra, E.; Gonzalez Diaz, G.; Sanchez Quesada, F. (Dept. Electricidad y Electronica, Univ. Complutense, Madrid (Spain))

    1990-01-01

    Current-voltage (J-V) and capacitance-frequency (C-F) measurements were taken for all-sputtered CdS/CuInSe{sub 2} solar cell heterojunctions, in the range 100 Hz - 10 MHz, to investigate the effect of interface states on the conduction mechanism. The samples analyzed had different compositions for the chalcopyrite CuInSe{sub 2} layer. All of the samples showed a hybrid tunneling/interface recombination mechanism with the major contribution coming from the interface recombination mechanism for devices having a stoichiometric or indium-rich CuInSe{sub 2} layer, and from the tunneling conduction mechanism for copper-rich devices. An estimation of the relative distribution of interface states has been performed. The values obtained for interface state density were as high as 6x10{sup 12} V{sup -1} cm{sup -2} for copper-rich heterojunctions, and were lower than 2x10{sup 11} V{sup -1} cm{sup -2} for devices having a stoichiometric or indium-rich CuInSe{sub 2} layer. (orig.).

  16. Effect of emitter layer doping concentration on the performance of a silicon thin film heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Zhang Lei; Shen Hong-Lie; Yue Zhi-Hao; Jiang Feng; Wu Tian-Ru; Pan Yuan-Yuan

    2013-01-01

    A novel type of n/i/i/p heterojunction solar cell with a-Si:H(15 nm)/a-Si:H(10 nm)/epitaxial c-Si(47 μm)/epitaxial c-Si(3 μm) structure is fabricated by using the layer transfer technique,and the emitter layer is deposited by hot wire chemical vapour deposition.The effect of the doping concentration of the emitter layer Sd (Sd=PH3/(PH3+SiH4+H2)) on the performance of the solar cell is studied by means of current density-voltage and external quantum efficiency.The results show that the conversion efficiency of the solar cell first increases to a maximum value and then decreases with Sd increasing from 0.1% to 0.4%.The best performance of the solar cell is obtained at Sd =0.2% with an open circuit voltage of 534 mV,a short circuit current density of 23.35 mA/cm2,a fill factor of 63.3%,and a conversion efficiency of 7.9%.

  17. Spontaneous Polarization and Bulk Photovoltaic Effect Driven by Polar Discontinuity in LaFeO_{3}/SrTiO_{3} Heterojunctions.

    Science.gov (United States)

    Nakamura, M; Kagawa, F; Tanigaki, T; Park, H S; Matsuda, T; Shindo, D; Tokura, Y; Kawasaki, M

    2016-04-15

    Structurally coherent and chemically abrupt interfaces formed between polar and nonpolar perovskite oxides provide an ideal platform for examining the purely electronic reconstruction known as the polar catastrophe and the emergence of mobile or bound charges at the interface. The appearance of mobile charges induced by the polar catastrophe is already established in the LaAlO_{3}/SrTiO_{3} heterojunctions. Although not experimentally verified, the polar catastrophe can also lead to the emergence of spontaneous polarization. We report that thin films of originally nonpolar LaFeO_{3} grown on SrTiO_{3} are converted to polar as a consequence of the polar catastrophe. The induced spontaneous polarization evokes photovoltaic properties distinct from conventional p-n junctions, such as a switching of the photocurrent direction by changing the interfacial atomic sequence. The control of the bulk polarization by engineering the interface demonstrated here will expand the possibilities for designing and realizing new polar materials with photovoltaic functions.

  18. Spontaneous Polarization and Bulk Photovoltaic Effect Driven by Polar Discontinuity in LaFeO3 /SrTiO3 Heterojunctions

    Science.gov (United States)

    Nakamura, M.; Kagawa, F.; Tanigaki, T.; Park, H. S.; Matsuda, T.; Shindo, D.; Tokura, Y.; Kawasaki, M.

    2016-04-01

    Structurally coherent and chemically abrupt interfaces formed between polar and nonpolar perovskite oxides provide an ideal platform for examining the purely electronic reconstruction known as the polar catastrophe and the emergence of mobile or bound charges at the interface. The appearance of mobile charges induced by the polar catastrophe is already established in the LaAlO3 /SrTiO3 heterojunctions. Although not experimentally verified, the polar catastrophe can also lead to the emergence of spontaneous polarization. We report that thin films of originally nonpolar LaFeO3 grown on SrTiO3 are converted to polar as a consequence of the polar catastrophe. The induced spontaneous polarization evokes photovoltaic properties distinct from conventional p -n junctions, such as a switching of the photocurrent direction by changing the interfacial atomic sequence. The control of the bulk polarization by engineering the interface demonstrated here will expand the possibilities for designing and realizing new polar materials with photovoltaic functions.

  19. Broadband All-Polymer Phototransistors with Nanostructured Bulk Heterojunction Layers of NIR-Sensing n-Type and Visible Light-Sensing p-Type Polymers.

    Science.gov (United States)

    Han, Hyemi; Nam, Sungho; Seo, Jooyeok; Lee, Chulyeon; Kim, Hwajeong; Bradley, Donal D C; Ha, Chang-Sik; Kim, Youngkyoo

    2015-11-13

    We report 'broadband light-sensing' all-polymer phototransistors with the nanostructured bulk heterojunction (BHJ) layers of visible (VIS) light-sensing electron-donating (p-type) polymer and near infrared (NIR) light-sensing electron-accepting (n-type) polymer. Poly[{2,5-bis-(2-ethylhexyl)-3,6-bis-(thien-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-diyl}-co-{2,2'-(2,1,3-benzothiadiazole)]-5,5'-diyl}] (PEHTPPD-BT), which is synthesized via Suzuki coupling and employed as the n-type polymer, shows strong optical absorption in the NIR region (up to 1100 nm) in the presence of weak absorption in the VIS range (400~600 nm). To strengthen the VIS absorption, poly(3-hexylthiophene) (P3HT) is introduced as the p-type polymer. All-polymer phototransistors with the BHJ (P3HT:PEHTPPD-BT) layers, featuring a peculiar nano-domain morphology, exhibit typical p-type transistor characteristics and efficiently detect broadband (VIS~NIR) lights. The maximum corrected responsivity (without contribution of dark current) reaches up to 85~88% (VIS) and 26~40% (NIR) of theoretical responsivity. The charge separation process between P3HT and PEHTPPD-BT components in the highest occupied molecular orbital is proposed as a major working mechanism for the effective NIR sensing.

  20. How High Local Charge Carrier Mobility and an Energy Cascade in a Three-Phase Bulk Heterojunction Enable >90% Quantum Efficiency

    KAUST Repository

    Burke, Timothy M.

    2013-12-27

    Charge generation in champion organic solar cells is highly efficient in spite of low bulk charge-carrier mobilities and short geminate-pair lifetimes. In this work, kinetic Monte Carlo simulations are used to understand efficient charge generation in terms of experimentally measured high local charge-carrier mobilities and energy cascades due to molecular mixing. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Si nanowires organic semiconductor hybrid heterojunction solar cells toward 10% efficiency.

    Science.gov (United States)

    He, Lining; Jiang, Changyun; Wang, Hao; Lai, Donny; Rusli

    2012-03-01

    High-efficiency hybrid solar cells are fabricated using a simple approach of spin coating a transparent hole transporting organic small molecule, 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD) on silicon nanowires (SiNWs) arrays prepared by electroless chemical etching. The characteristics of the hybrid cells are investigated as a function of SiNWs length from 0.15 to 5 μm. A maximum average power conversion efficiency of 9.92% has been achieved from 0.35 μm length SiNWs cells, despite a 12% shadowing loss and the absence of antireflective coating and back surface field enhancement. It is found that enhanced aggregations in longer SiNWs limit the cell performance due to increased series resistance and higher carrier recombination in the shorter wavelength region. The effects of the Si substrate doping concentrations on the performance of the cells are also investigated. Cells with higher substrate doping concentration exhibit a significant drop in the incident photons-to-current conversion efficiency (IPCE) in the near infrared region. Nevertheless, a promising short circuit current density of 19 mA/cm(2) and IPCE peak of 57% have been achieved for a 0.9 μm length SiNWs cell fabricated on a highly doped substrate with a minority-carrier diffusion length of only 15 μm. The results suggest that such hybrid cells can potentially be realized using Si thin films instead of bulk substrates. This is promising towards realizing low-cost and high-efficiency SiNWs/organic hybrid solar cells. PMID:22391479

  2. Optical and electronic proprieties of thin films based on (Z-5-(4-chlorobenzylidene-3-(2-ethoxyphenyl-2 thioxothiazolidin-4-one, (CBBTZ and possible application as exciton-blocking layer in heterojunction organic solar cells

    Directory of Open Access Journals (Sweden)

    Morsli M.

    2012-06-01

    Full Text Available In this work, organic thin film solar cells with structures based on CuPc/C60 bulk heterojunctions, have been fabricated and characterized. The effect of introducing an exciton blocking layer (EBL between the active layer and the metal layer in the solar cell was investigated. For that (Z-5-(4-chlorobenzylidene-3-(2-ethoxyphenyl-2-thioxothiazolidin-4-one, that we called (CBBTZ has been synthesized, characterized and probed as EBL. It was shown that optimized structures containing EBLs resulted in an improvement in solar cell conversion efficiencies. The energy levels corresponding to the highest occupied molecular orbital (HOMO and the lowest unoccupied molecular orbital (LUMO of the CBBTZ have been determined from the first oxidation and reduction potential respectively, using cyclic voltametric (CV measurements. From CV curves, CBBTZ in dichloromethane showed a one electron reversible reduction and oxidation waves. The values of its HOMO and LUMO have been estimated to be 6.42 eV and 3.42 eV respectively. Such values show that CBBTZ could be probed as EBL in organic solar cells based on the ED/EA couple copper phthalocyanine(CuPc/fullerene (C60. The photovoltaic solar cells have been obtained by sequential deposition under vacuum of the different films where their thicknesses were measured in situ by a quartz monitor. When obtained, the averaged efficiency of the cells using the CBBTZ is higher than that achieved without EBL layer.

  3. Correlation of Interfacial Transportation Properties of CdS/CdTe Heterojunction and Performance of CdTe Polycrystalline Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Guanggen Zeng

    2015-01-01

    Full Text Available The light and dark output performances of CdS/CdTe solar cells made by close-spaced sublimation (CSS were investigated to elucidate the transportation properties of carriers at CdS/CdTe heterojunction interface. It has been found that the interfacial transportation properties were relatively sensitive to variations of the characteristics of heterojunction due to the series resistance and shunting effects. For the high quality cell with 12.1% efficiency, narrow depletion region of ~1.1 microns and large electric field intensity of ~1.3 V/μm allow the sufficient energy-band bending close to CdS layer at CdS/CdTe heterojunction, which changes the carrier transportation mechanism from emission to diffusion and leads to the optimal rectifying characteristics with small dark saturation current density ~6.4 × 10−10 A/cm2. As a result, the schematic diagram of heterojunction band structure corresponding to various performances of solar cells has also been presented.

  4. Low cost back contact heterojunction solar cells on thin c-Si wafers. Integrating laser and thin film processing for improved manufacturability

    Energy Technology Data Exchange (ETDEWEB)

    Hegedus, Steven S. [Univ. of Delaware, Newark, DE (United States)

    2015-09-08

    An interdigitated back contact (IBC) Si wafer solar cell with deposited a-Si heterojunction (HJ) emitter and contacts is considered the ultimate single junction Si solar cell design. This was confirmed in 2014 by both Panasonic and Sharp Solar producing IBC-HJ cells breaking the previous record Si solar cell efficiency of 25%. But manufacturability at low cost is a concern for the complex IBC-HJ device structure. In this research program, our goals were to addressed the broad industry need for a high-efficiency c-Si cell that overcomes the dominant module cost barriers by 1) developing thin Si wafers synthesized by innovative, kerfless techniques; 2) integrating laser-based processing into most aspects of solar cell fabrication, ensuring high speed and low thermal budgets ; 3) developing an all back contact cell structure compatible with thin wafers using a simplified, low-temperature fabrication process; and 4) designing the contact patterning to enable simplified module assembly. There were a number of significant achievements from this 3 year program. Regarding the front surface, we developed and applied new method to characterize critical interface recombination parameters including interface defect density Dit and hole and electron capture cross-section for use as input for 2D simulation of the IBC cell to guide design and loss analysis. We optimized the antireflection and passivation properties of the front surface texture and a-Si/a-SiN/a-SiC stack depositions to obtain a very low (< 6 mA/cm2) front surface optical losses (reflection and absorption) while maintaining excellent surface passivation (SRV<5 cm/s). We worked with kerfless wafer manufacturers to apply defect-engineering techniques to improve bulk minority-carrier lifetime of thin kerfless wafers by both reducing initial impurities during growth and developing post-growth gettering techniques. This led insights about the kinetics of nickel, chromium, and dislocations in PV-grade silicon and to

  5. Low cost back contact heterojunction solar cells on thin c-Si wafers. integrating laser and thin film processing for improved manufacturability

    Energy Technology Data Exchange (ETDEWEB)

    Hegedus, Steven S. [Univ. of Delaware, Newark, DE (United States)

    2015-09-08

    An interdigitated back contact (IBC) Si wafer solar cell with deposited a-Si heterojunction (HJ) emitter and contacts is considered the ultimate single junction Si solar cell design. This was confirmed in 2014 by both Panasonic and Sharp Solar producing IBC-HJ cells breaking the previous record Si solar cell efficiency of 25%. But manufacturability at low cost is a concern for the complex IBC-HJ device structure. In this research program, our goals were to addressed the broad industry need for a high-efficiency c-Si cell that overcomes the dominant module cost barriers by 1) developing thin Si wafers synthesized by innovative, kerfless techniques; 2) integrating laser-based processing into most aspects of solar cell fabrication, ensuring high speed and low thermal budgets ; 3) developing an all back contact cell structure compatible with thin wafers using a simplified, low-temperature fabrication process; and 4) designing the contact patterning to enable simplified module assembly. There were a number of significant achievements from this 3 year program. Regarding the front surface, we developed and applied new method to characterize critical interface recombination parameters including interface defect density Dit and hole and electron capture cross-section for use as input for 2D simulation of the IBC cell to guide design and loss analysis. We optimized the antireflection and passivation properties of the front surface texture and a-Si/a-SiN/a-SiC stack depositions to obtain a very low (< 6 mA/cm2) front surface optical losses (reflection and absorption) while maintaining excellent surface passivation (SRV<5 cm/s). We worked with kerfless wafer manufacturers to apply defect-engineering techniques to improve bulk minority-carrier lifetime of thin kerfless wafers by both reducing initial impurities during growth and developing post-growth gettering techniques. This led insights about the kinetics of nickel, chromium, and dislocations in PV-grade silicon and to

  6. Strategies for optimizing organic solar cells. Correlation between morphology and performance in DCV6T-C{sub 60} heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Wynands, David

    2011-02-04

    This work investigates organic solar cells made of small molecules. Using the material system {alpha}{omega}-bis(dicyanovinylene)-sexithiophene (DCV6T)-C{sub 60} as model, the correlation between the photovoltaic active layer morphology and performance of the solar cell is studied. The chosen method for controlling the layer morphology is applying different substrate temperatures (T{sub sub}) during the deposition of the layer. In neat DCV6T layers, substrate heating induces higher crystallinity as is shown by X-ray diffraction and atomic force microscopy (AFM). The absorption spectrum displays a more distinct fine structure, a redshift of the absorption peaks by up to 11 nm and a significant increase of the low energy absorption band at T{sub sub}=120 C compared to T{sub sub}=30 C. Contrary to general expectations, the hole mobility as measured in field effect transistors and with the method of charge extraction by linearly increasing voltage (CELIV) does not increase in samples with higher crystallinity. In mixed layers, investigations by AFM and UV-Vis spectroscopy reveal a stronger phase separation induced by substrate heating, leading to larger domains of DCV6T. This is indicated by an increased grain size and roughness of the topography, the increase of the DCV6T luminescence signal, and the more distinct fine structure of the DCV6T related absorption. Based on the results of the morphology analysis, the effect of different substrate temperatures on the performance of solar cells with flat and mixed DCV6T-C{sub 60} heterojunctions is investigated. In flat heterojunction solar cells, a slight increase of the photocurrent by about 10% is observed upon substrate heating, attributed to the increase of DCV6T absorption. In mixed DCV6T:C{sub 60} heterojunction solar cells, much more pronounced enhancements are achieved. By varying the substrate temperature from -7 C to 120 C, it is shown that the stronger phase separation upon substrate heating facilitates the

  7. Atomic layer deposition precursor step repetition and surface plasma pretreatment influence on semiconductor–insulator–semiconductor heterojunction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Talkenberg, Florian, E-mail: florian.talkenberg@ipht-jena.de; Illhardt, Stefan; Schmidl, Gabriele; Schleusener, Alexander; Sivakov, Vladimir [Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena (Germany); Radnóczi, György Zoltán; Pécz, Béla [Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege Miklós u. 29-33, H-1121 Budapest (Hungary); Dikhanbayev, Kadyrjan; Mussabek, Gauhar [Department of Physics and Engineering, al-Farabi Kazakh National University, 71 al-Farabi Ave., 050040 Almaty (Kazakhstan); Gudovskikh, Alexander [Nanotechnology Research and Education Centre, St. Petersburg Academic University, Russian Academy of Sciences, Hlopina Str. 8/3, 194021 St. Petersburg (Russian Federation)

    2015-07-15

    Semiconductor–insulator–semiconductor heterojunction solar cells were prepared using atomic layer deposition (ALD) technique. The silicon surface was treated with oxygen and hydrogen plasma in different orders before dielectric layer deposition. A plasma-enhanced ALD process was applied to deposit dielectric Al{sub 2}O{sub 3} on the plasma pretreated n-type Si(100) substrate. Aluminum doped zinc oxide (Al:ZnO or AZO) was deposited by thermal ALD and serves as transparent conductive oxide. Based on transmission electron microscopy studies the presence of thin silicon oxide (SiO{sub x}) layer was detected at the Si/Al{sub 2}O{sub 3} interface. The SiO{sub x} formation depends on the initial growth behavior of Al{sub 2}O{sub 3} and has significant influence on solar cell parameters. The authors demonstrate that a hydrogen plasma pretreatment and a precursor dose step repetition of a single precursor improve the initial growth behavior of Al{sub 2}O{sub 3} and avoid the SiO{sub x} generation. Furthermore, it improves the solar cell performance, which indicates a change of the Si/Al{sub 2}O{sub 3} interface states.

  8. Atomic layer deposition precursor step repetition and surface plasma pretreatment influence on semiconductor–insulator–semiconductor heterojunction solar cell

    International Nuclear Information System (INIS)

    Semiconductor–insulator–semiconductor heterojunction solar cells were prepared using atomic layer deposition (ALD) technique. The silicon surface was treated with oxygen and hydrogen plasma in different orders before dielectric layer deposition. A plasma-enhanced ALD process was applied to deposit dielectric Al2O3 on the plasma pretreated n-type Si(100) substrate. Aluminum doped zinc oxide (Al:ZnO or AZO) was deposited by thermal ALD and serves as transparent conductive oxide. Based on transmission electron microscopy studies the presence of thin silicon oxide (SiOx) layer was detected at the Si/Al2O3 interface. The SiOx formation depends on the initial growth behavior of Al2O3 and has significant influence on solar cell parameters. The authors demonstrate that a hydrogen plasma pretreatment and a precursor dose step repetition of a single precursor improve the initial growth behavior of Al2O3 and avoid the SiOx generation. Furthermore, it improves the solar cell performance, which indicates a change of the Si/Al2O3 interface states

  9. Development of LASER fired contacts on silicon heterojunction solar cells for the application to rear contact structures

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D.; Desrues, T.; Ribeyron, P.J. [INES-CEA, Le Bourget du Lac (France); Orpella, A.; Martin, I.; Voz, C.; Alcubilla, R. [Grup de Recerca en Micro i Nanotecnologies, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2010-04-15

    In this work, we present our progress in contacting both doped and undoped a-Si:H layers using a LASER tool and show some applications for three different HJ solar cell designs: standard (p-type), rear emitter (n-type) and back contact (n-type). First, we have fabricated 25 cm{sup 2} standard and rear emitter double heterojunction (DHJ) solar cells on planar 1-5 {omega}.cm n-type FZ c-Si wafers using intrinsic instead of the p-doped a-Si:H layers. The influence of the different parameters of the LASER firing (pitch, number of pulses and energy) has been deeply studied to find optimized conditions. Solar cells have been obtained systematically with reasonable efficiencies although we have observed that the V{sub oc} is limiting the efficiency. Finally, we have also performed the Laser Fired Contacts (LFC) on lowly-doped (p) a-Si:H layers to compare the results obtained. We have observed that the LFC of the rear emitter contact enhances both short circuit current and fill factor while keeping the same V{sub oc} (646 mV). This leads to a 0.8% absolute increase of the cell efficiency. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. The simulation of physical mechanism for HTM-free perovskite organic lead iodide planar heterojunction solar cells

    International Nuclear Information System (INIS)

    Recently, organo-metal halide perovskites have attracted much attention from the scientific community because of their successful application in the absorber layer of low-cost solar cells. For the further improvement of the performance of such cells, a thorough understanding of the influence of the material properties on the working mechanism of a device is very necessary and important. In this study, two-dimensional modeling of hole transport material free planar heterojunction solar cells was performed, in which electromagnetic simulation was directly linked to carrier transport calculations. An optimum absorber thickness of 200 nm was reproduced in the simulation at carrier diffusion length of 100 nm, in good agreement with previous experiments. This optimum thickness increased with the increase of diffusion length, and an efficiency of about 11% was obtained at 300 nm with a diffusion length of 300 nm. Finally, it was demonstrated that the relatively low efficiency of such solar cells was directly related to the low short-circuit photocurrent density (J SC) and the low open-circuit voltage (V OC) due to the insufficient absorption of the long-wavelength region and the nearly intrinsic doping concentration, respectively. (paper)

  11. Effect of relative humidity on crystal growth, device performance and hysteresis in planar heterojunction perovskite solar cells

    Science.gov (United States)

    Gangishetty, Mahesh K.; Scott, Robert W. J.; Kelly, Timothy L.

    2016-03-01

    Due to the hygroscopic nature of organolead halide perovskites, humidity is one of the most important factors affecting the efficiency and longevity of perovskite solar cells. Although humidity has a long term detrimental effect on device performance, it also plays a key role during the initial growth of perovskite crystals. Here we demonstrate that atmospheric relative humidity (RH) plays a key role during the formation of perovskite thin films via the sequential deposition technique. Our results indicate that the RH has a substantial impact on the crystallization process, and hence on device performance. SEM and pXRD analysis show an increase in crystallite size with increasing humidity. At low RH, the formation of small cubic crystallites with large gaps between them is observed. The presence of these voids adversely affects device performance and leads to substantial hysteresis in the device. At higher RH, the perovskite crystals are larger in size, with better connectivity between the crystallites. This produced efficient planar heterojunction solar cells with low hysteresis. By careful control of the RH during the cell fabrication process, efficiencies of up to 12.2% are reached using P3HT as the hole-transport material.Due to the hygroscopic nature of organolead halide perovskites, humidity is one of the most important factors affecting the efficiency and longevity of perovskite solar cells. Although humidity has a long term detrimental effect on device performance, it also plays a key role during the initial growth of perovskite crystals. Here we demonstrate that atmospheric relative humidity (RH) plays a key role during the formation of perovskite thin films via the sequential deposition technique. Our results indicate that the RH has a substantial impact on the crystallization process, and hence on device performance. SEM and pXRD analysis show an increase in crystallite size with increasing humidity. At low RH, the formation of small cubic crystallites

  12. Indium-tin oxide films obtained by DC magnetron sputtering for improved Si heterojunction solar cell applications

    Institute of Scientific and Technical Information of China (English)

    谷锦华; 司嘉乐; 王九秀; 冯亚阳; 郜小勇; 卢景霄

    2015-01-01

    The indium–tin oxide (ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction (HJ) solar cells. To obtain high transmittance and low resistivity ITO films by direct-current (DC) magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4×10−4Ω·m and average transmittance of 89%in the wavelength range of 380–780 nm were obtained under the optimized conditions:oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si:H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage (Voc) of 0.626 V, a filling factor (FF) of 0.50, and a short circuit current density (Jsc) of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si:H layer was inserted between the (p) a-Si:H and (n) c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si:H.

  13. Carbon Nanotube-Silicon Nanowire Heterojunction Solar Cells with Gas-Dependent Photovoltaic Performances and Their Application in Self-Powered NO2 Detecting

    Science.gov (United States)

    Jia, Yi; Zhang, Zexia; Xiao, Lin; Lv, Ruitao

    2016-06-01

    A multifunctional device combining photovoltaic conversion and toxic gas sensitivity is reported. In this device, carbon nanotube (CNT) membranes are used to cover onto silicon nanowire (SiNW) arrays to form heterojunction. The porous structure and large specific surface area in the heterojunction structure are both benefits for gas adsorption. In virtue of these merits, gas doping is a feasible method to improve cell's performance and the device can also work as a self-powered gas sensor beyond a solar cell. It shows a significant improvement in cell efficiency (more than 200 times) after NO2 molecules doping (device working as a solar cell) and a fast, reversible response property for NO2 detection (device working as a gas sensor). Such multifunctional CNT-SiNW structure can be expected to open a new avenue for developing self-powered, efficient toxic gas-sensing devices in the future.

  14. Carbon Nanotube-Silicon Nanowire Heterojunction Solar Cells with Gas-Dependent Photovoltaic Performances and Their Application in Self-Powered NO2 Detecting.

    Science.gov (United States)

    Jia, Yi; Zhang, Zexia; Xiao, Lin; Lv, Ruitao

    2016-12-01

    A multifunctional device combining photovoltaic conversion and toxic gas sensitivity is reported. In this device, carbon nanotube (CNT) membranes are used to cover onto silicon nanowire (SiNW) arrays to form heterojunction. The porous structure and large specific surface area in the heterojunction structure are both benefits for gas adsorption. In virtue of these merits, gas doping is a feasible method to improve cell's performance and the device can also work as a self-powered gas sensor beyond a solar cell. It shows a significant improvement in cell efficiency (more than 200 times) after NO2 molecules doping (device working as a solar cell) and a fast, reversible response property for NO2 detection (device working as a gas sensor). Such multifunctional CNT-SiNW structure can be expected to open a new avenue for developing self-powered, efficient toxic gas-sensing devices in the future. PMID:27299654

  15. Carbon Nanotube-Silicon Nanowire Heterojunction Solar Cells with Gas-Dependent Photovoltaic Performances and Their Application in Self-Powered NO2 Detecting.

    Science.gov (United States)

    Jia, Yi; Zhang, Zexia; Xiao, Lin; Lv, Ruitao

    2016-12-01

    A multifunctional device combining photovoltaic conversion and toxic gas sensitivity is reported. In this device, carbon nanotube (CNT) membranes are used to cover onto silicon nanowire (SiNW) arrays to form heterojunction. The porous structure and large specific surface area in the heterojunction structure are both benefits for gas adsorption. In virtue of these merits, gas doping is a feasible method to improve cell's performance and the device can also work as a self-powered gas sensor beyond a solar cell. It shows a significant improvement in cell efficiency (more than 200 times) after NO2 molecules doping (device working as a solar cell) and a fast, reversible response property for NO2 detection (device working as a gas sensor). Such multifunctional CNT-SiNW structure can be expected to open a new avenue for developing self-powered, efficient toxic gas-sensing devices in the future.

  16. The Importance of End Groups for Solution-Processed Small-Molecule Bulk-Heterojunction Photovoltaic Cells.

    Science.gov (United States)

    Duan, Ruomeng; Cui, Yong; Zhao, Yanfei; Li, Chen; Chen, Long; Hou, Jianhui; Wagner, Manfred; Baumgarten, Martin; He, Chang; Müllen, Klaus

    2016-05-10

    End groups in small-molecule photovoltaic materials are important owing to their strong influence on molecular stability, solubility, energy levels, and aggregation behaviors. In this work, a series of donor-acceptor pentads (D2 -A-D1 -A-D2 ) were designed and synthesized, aiming to investigate the effect of the end groups on the materials properties and photovoltaic device performance. These molecules share identical central A-D1 -A triads (with benzodithiophene as D1 and 6-carbonyl-thieno[3,4-b]thiophene as A), but with various D2 end groups composed of alkyl-substituted thiophene (T), thieno[3,2-b]thiophene (TT), and 2,2'-bithiophene (BT). The results indicate a relationship between conjugated segment/alkyl chain length of the end groups and the photovoltaic performance, which contributes to the evolving molecular design principles for high efficiency organic solar cells.

  17. The Importance of End Groups for Solution-Processed Small-Molecule Bulk-Heterojunction Photovoltaic Cells.

    Science.gov (United States)

    Duan, Ruomeng; Cui, Yong; Zhao, Yanfei; Li, Chen; Chen, Long; Hou, Jianhui; Wagner, Manfred; Baumgarten, Martin; He, Chang; Müllen, Klaus

    2016-05-10

    End groups in small-molecule photovoltaic materials are important owing to their strong influence on molecular stability, solubility, energy levels, and aggregation behaviors. In this work, a series of donor-acceptor pentads (D2 -A-D1 -A-D2 ) were designed and synthesized, aiming to investigate the effect of the end groups on the materials properties and photovoltaic device performance. These molecules share identical central A-D1 -A triads (with benzodithiophene as D1 and 6-carbonyl-thieno[3,4-b]thiophene as A), but with various D2 end groups composed of alkyl-substituted thiophene (T), thieno[3,2-b]thiophene (TT), and 2,2'-bithiophene (BT). The results indicate a relationship between conjugated segment/alkyl chain length of the end groups and the photovoltaic performance, which contributes to the evolving molecular design principles for high efficiency organic solar cells. PMID:27008919

  18. Sequentially Different AB Diblock and ABA Triblock Copolymers as P3HT:PCBM Interfacial Compatibilizers for Bulk-Heterojunction Photovoltaics.

    Science.gov (United States)

    Fujita, Hiroyuki; Michinobu, Tsuyoshi; Fukuta, Seijiro; Koganezawa, Tomoyuki; Higashihara, Tomoya

    2016-03-01

    The P3HT:PCBM (P3HT = poly(3-hexylthiophene, PCBM = phenyl-C61-butyric acid methyl ester) bulk-heterojunction (BHJ) organic photovoltaic (OPV) cells using the AB diblock and ABA triblock copolymers (A = polystyrene derivative with donor-acceptor units (PTCNE) and B = P3HT) as compatibilizers were fabricated. Under the optimized blend ratio of the block copolymer, the power conversion efficiency (PCE) was enhanced. This PCE enhancement was clearly related to the increased short-circuit current (J(sc)) and fill factor (FF). The incident photon to current efficiency (IPCE) measurement suggested that the P3HT crystallinity was improved upon addition of the block copolymers. The increased P3HT crystallinity was consistent with the increased photovoltaic parameters, such as J(sc), FF, and consequently the PCE. The surface energies of these block copolymers suggested their thermodynamically stable location at the interface of P3HT:PCBM, showing the efficient compatibilizing performance, resulting in enlarging and fixing the interfacial area and suppressing the recombination of the generated carriers. Grazing incidence X-ray scattering (GIXS) results confirmed the superior compatibilizing performance of the ABA triblock copolymer when compared to the AB diblock copolymer by the fact that, after blending the ABA triblock copolymer in the P3HT:PCBM system, the enhanced crystallinity of matrix P3HT was observed in the excluded areas of the less-aggregated PCBM domains, changing the P3HT crystalline domain orientation from "edge-on" to "isotropic". This is, to the best of our knowledge, the first sequential effect (AB vs ABA) of the block copolymers on the compatibilizing performances based on BHJ OPV device systems.

  19. Sequentially Different AB Diblock and ABA Triblock Copolymers as P3HT:PCBM Interfacial Compatibilizers for Bulk-Heterojunction Photovoltaics.

    Science.gov (United States)

    Fujita, Hiroyuki; Michinobu, Tsuyoshi; Fukuta, Seijiro; Koganezawa, Tomoyuki; Higashihara, Tomoya

    2016-03-01

    The P3HT:PCBM (P3HT = poly(3-hexylthiophene, PCBM = phenyl-C61-butyric acid methyl ester) bulk-heterojunction (BHJ) organic photovoltaic (OPV) cells using the AB diblock and ABA triblock copolymers (A = polystyrene derivative with donor-acceptor units (PTCNE) and B = P3HT) as compatibilizers were fabricated. Under the optimized blend ratio of the block copolymer, the power conversion efficiency (PCE) was enhanced. This PCE enhancement was clearly related to the increased short-circuit current (J(sc)) and fill factor (FF). The incident photon to current efficiency (IPCE) measurement suggested that the P3HT crystallinity was improved upon addition of the block copolymers. The increased P3HT crystallinity was consistent with the increased photovoltaic parameters, such as J(sc), FF, and consequently the PCE. The surface energies of these block copolymers suggested their thermodynamically stable location at the interface of P3HT:PCBM, showing the efficient compatibilizing performance, resulting in enlarging and fixing the interfacial area and suppressing the recombination of the generated carriers. Grazing incidence X-ray scattering (GIXS) results confirmed the superior compatibilizing performance of the ABA triblock copolymer when compared to the AB diblock copolymer by the fact that, after blending the ABA triblock copolymer in the P3HT:PCBM system, the enhanced crystallinity of matrix P3HT was observed in the excluded areas of the less-aggregated PCBM domains, changing the P3HT crystalline domain orientation from "edge-on" to "isotropic". This is, to the best of our knowledge, the first sequential effect (AB vs ABA) of the block copolymers on the compatibilizing performances based on BHJ OPV device systems. PMID:26864393

  20. Improvement of Electrochemically Deposited Cu2O/ZnO Heterojunction Solar Cells by Modulation of Deposition Current

    Science.gov (United States)

    Song, Ying; Ichimura, Masaya

    2012-10-01

    Cu2O thin films were deposited on indium-tin-oxide-coated glass from an aqueous solution containing CuSO4, lactic acid and KOH by the galvanostatic electrochemical deposition at 40 °C with several different current densities. The photo-absorption of Cu2O was increased and the conduction type was changed from weak p-type to clear p-type by raising the current value. Cu2O(2)/Cu2O(1)/ZnO three-layer heterojunctions were fabricated electrochemically by modulation of deposition current density of Cu2O. The first Cu2O layer Cu2O(1) was deposited at a lower deposition current, and the second one Cu2O(2) at a higher current. Under the optimized condition, the conversion efficiency of a Cu2O(2)/Cu2O(1)/ZnO solar cell was found to be higher than that of a Cu2O(1)/ZnO solar cell.

  1. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    Science.gov (United States)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-01

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  2. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    Science.gov (United States)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-01

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation. PMID:27232727

  3. Demonstration of solar-blind AlxGa1−xN-based heterojunction phototransistors

    International Nuclear Information System (INIS)

    Al0.4Ga0.6N/Al0.65Ga0.35N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 103 was obtained at 6 V bias

  4. Degradation of bulk diffusion length in CZ silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Reiss, J.H.; King, R.R.; Mitchell, K.W. [Siemens Solar Industries, Camarillo, CA (United States)

    1995-08-01

    Commercially-produced, unencapsulated, CZ silicon solar cells can lose 3 to 4% of their initial efficiency after exposure to light. After this initial, rapid ( < 30 min.) decrease, the cell power output remains stable. The cell performance recovers in a matter of hours in the dark at room temperature, and degrades again under light exposure. The different conditions under which CZ silicon cells degrade, and the reverse process, annealing, are characterized with the methods of spectral response and current-voltage (I-V) measurements. Iron impurities are a possible cause of this effect.

  5. Application of PECVD for bulk and surface passivation of high efficiency silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Krygowski, T.; Doshi, P.; Cai, L.; Doolittle, A.; Rohatgi, A. [Georgia Inst. of Technology, Atlanta, GA (United States)

    1995-08-01

    Plasma enhanced chemical vapor deposition (PECVD) passivation of bulk and surface defects has been shown to be an important technique to improve the performance of multicrystalline silicon (mc-Si) and single crystalline silicon solar cells. In this paper, we report the status of our on-going investigation into the bulk and surface passivation properties of PECVD insulators for photovoltaic applications. The objective of this paper is to demonstrate the ability of PECVD films to passivate the front (emitter) surface, bulk, and back surface by proper tailoring of deposition and post-PECVD annealing conditions.

  6. Engineering Schottky contacts in open-air fabricated heterojunction solar cells to enable high performance and ohmic charge transport.

    Science.gov (United States)

    Hoye, Robert L Z; Heffernan, Shane; Ievskaya, Yulia; Sadhanala, Aditya; Flewitt, Andrew; Friend, Richard H; MacManus-Driscoll, Judith L; Musselman, Kevin P

    2014-12-24

    The efficiencies of open-air processed Cu2O/Zn(1-x)Mg(x)O heterojunction solar cells are doubled by reducing the effect of the Schottky barrier between Zn(1-x)Mg(x)O and the indium tin oxide (ITO) top contact. By depositing Zn(1-x)Mg(x)O with a long band-tail, charge flows through the Zn(1-x)Mg(x)O/ITO Schottky barrier without rectification by hopping between the sub-bandgap states. High current densities are obtained by controlling the Zn(1-x)Mg(x)O thickness to ensure that the Schottky barrier is spatially removed from the p-n junction, allowing the full built-in potential to form, in addition to taking advantage of the increased electrical conductivity of the Zn(1-x)Mg(x)O films with increasing thickness. This work therefore shows that the Zn(1-x)Mg(x)O window layer sub-bandgap state density and thickness are critical parameters that can be engineered to minimize the effect of Schottky barriers on device performance. More generally, these findings show how to improve the performance of other photovoltaic system reliant on transparent top contacts, e.g., CZTS and CIGS. PMID:25418326

  7. Radiation effect on the optical and electrical properties of CdSe(In)/p-Si heterojunction photovoltaic solar cells

    Institute of Scientific and Technical Information of China (English)

    M. Ashry; S. Fares

    2012-01-01

    The efficiency and radiation resistance of solar cells are graded.They are then fabricated in the form of n-CdeSe(In)/p-Si heterojunction cells by electron beam evaporation of a stoichiomteric mixture of CdSe and In to make a thin film on a p-Si single crystal wafer with a thickness of 100 μm and a resistivity of ~ 1.5Ω·cm at a temperature of 473 K.The short-circuit current density (jsc),open-circuit voltage (Voc),fill factor (ff) and conversion efficiency (η) under 100 mW/cm2 (AM1) intensity,are 20 mA/cm2,0.49 V,0.71 and 6% respectively.The cells were exposed to different electron doses (electron beam accelerator of energy 1.5 MeV,and beam intensity 25 mA).The cell performance parameters are measured and discussed before and after gamma and electron beam irradiation.

  8. The Effect of Molecular Structure and Environment on the Miscibility and Diffusivity in Polythiophene-Methanofullerene Bulk Heterojunctions: Theory and Modeling with the RISM Approach

    Directory of Open Access Journals (Sweden)

    Alexander E. Kobryn

    2016-04-01

    Full Text Available Although better means to model the properties of bulk heterojunction molecular blends are much needed in the field of organic optoelectronics, only a small subset of methods based on molecular dynamics- and Monte Carlo-based approaches have been hitherto employed to guide or replace empirical characterization and testing. Here, we present the first use of the integral equation theory of molecular liquids in modelling the structural properties of blends of phenyl-C61-butyric acid methyl ester (PCBM with poly(3-hexylthiophene (P3HT and a carboxylated poly(3-butylthiophene (P3BT, respectively. For this, we use the Reference Interaction Site Model (RISM with the Universal Force Field (UFF to compute the microscopic structure of blends and obtain insight into the miscibility of its components. Input parameters for RISM, such as optimized molecular geometries and charge distribution of interaction sites, are derived by the Density Functional Theory (DFT methods. We also run Molecular Dynamics (MD simulation to compare the diffusivity of the PCBM in binary blends with P3HT and P3BT, respectively. A remarkably good agreement with available experimental data and results of alternative modelling/simulation is observed for PCBM in the P3HT system. We interpret this as a step in the validation of the use of our approach for organic photovoltaics and support of its results for new systems that do not have reference data for comparison or calibration. In particular, for the less-studied P3BT, our results show that expectations about its performance in binary blends with PCBM may be overestimated, as it does not demonstrate the required level of miscibility and short-range structural organization. In addition, the simulated mobility of PCBM in P3BT is somewhat higher than what is expected for polymer blends and falls into a range typical for fluids. The significance of our predictive multi-scale modelling lies in the insights it offers into nanoscale

  9. Impact of Improved Solar Forecasts on Bulk Power System Operations in ISO-NE (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Brancucci Martinez-Anido, C.; Florita, A.; Hodge, B.M.

    2014-11-01

    The diurnal nature of solar power is made uncertain by variable cloud cover and the influence of atmospheric conditions on irradiance scattering processes. Its forecasting has become increasingly important to the unit commitment and dispatch process for efficient scheduling of generators in power system operations. This presentation is an overview of a study that examines the value of improved solar forecasts on Bulk Power System Operations.

  10. Heterojunction PbS Nanocrystal Solar Cells with Oxide Charge-Transport Layers

    KAUST Repository

    Hyun, Byung-Ryool

    2013-12-23

    Oxides are commonly employed as electron-transport layers in optoelectronic devices based on semiconductor nanocrystals, but are relatively rare as hole-transport layers. We report studies of NiO hole-transport layers in PbS nanocrystal photovoltaic structures. Transient fluorescence experiments are used to verify the relevant energy levels for hole transfer. On the basis of these results, planar heterojunction devices with ZnO as the photoanode and NiO as the photocathode were fabricated and characterized. Solution-processed devices were used to systematically study the dependence on nanocrystal size and achieve conversion efficiency as high as 2.5%. Optical modeling indicates that optimum performance should be obtained with thinner oxide layers than can be produced reliably by solution casting. Roomerature sputtering allows deposition of oxide layers as thin as 10 nm, which enables optimization of device performance with respect to the thickness of the charge-transport layers. The best devices achieve an open-circuit voltage of 0.72 V and efficiency of 5.3% while eliminating most organic material from the structure and being compatible with tandem structures. © 2013 American Chemical Society.

  11. The effects of CdCl sub 2 on the electronic properties of molecular-beam epitaxially grown CdTe/CdS heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ringel, S.A.; Smith, A.W.; MacDougal, M.H.; Rohatgi, A. (School of Electrical Engineering and Microelectronics Research Center, Georgia Institute of Technology, Atlanta, Georgia 30332 (US))

    1991-07-15

    Significant improvements in CdTe/CdS solar cell efficiency are commonly observed as a result of a postdeposition CdCl{sub 2} dip followed by a 400 {degree}C heat treatment during cell processing which increases CdTe grain size. In this paper, we investigate the electronic mechanisms responsible for CdCl{sub 2}-induced improvement in cell performance along with possible performance-limiting defects resulting from this process in molecular-beam epitaxy-grown polycrystalline CdTe/CdS solar cells. Current density-voltage-temperature ({ital J}-{ital V}-{ital T}) analysis revealed that the CdCl{sub 2} treatment changes the dominant current transport mechanism from interface recombination/tunneling to depletion region recombination, suggesting a decrease in the density and dominance of interface states due to the CdCl{sub 2} treatment. It is shown that the change in transport mechanism is associated with (a) an increase in heterojunction barrier height from 0.56 to 0.85 eV, (b) a decrease in dark leakage current from 4.7{times}10{sup {minus}7} A/cm{sup 2} to 2.6{times}10{sup {minus}9} A/cm{sup 2} and, (c) an increase in cell {ital V}{sub oc} from 385 to 720 mV. The CdCl{sub 2} also improved the optical response of the cell. Substantial increases in the surface photovoltage and quantum efficiency accompanied by a decrease in the bias dependence of the spectral response in the CdCl{sub 2}-treated structures indicate that the CdCl{sub 2} treatment improves carrier collection from the bulk as well as across the heterointerface. However, deep level transient spectroscopy measurements detected a hole trap within the CdTe depletion region of the CdCl{sub 2}-treated devices at {ital E}{sub {ital v}} + 0.64 eV which is attributed to the formation of {ital V}{sub Cd}-related defects during the annealing process after the CdCl{sub 2} dip.

  12. The effects of CdCl2 on the electronic properties of molecular-beam epitaxially grown CdTe/CdS heterojunction solar cells

    Science.gov (United States)

    Ringel, S. A.; Smith, A. W.; MacDougal, M. H.; Rohatgi, A.

    1991-07-01

    Significant improvements in CdTe/CdS solar cell efficiency are commonly observed as a result of a postdeposition CdCl2 dip followed by a 400 °C heat treatment during cell processing which increases CdTe grain size. In this paper, we investigate the electronic mechanisms responsible for CdCl2-induced improvement in cell performance along with possible performance-limiting defects resulting from this process in molecular-beam epitaxy-grown polycrystalline CdTe/CdS solar cells. Current density-voltage-temperature (J-V-T) analysis revealed that the CdCl2 treatment changes the dominant current transport mechanism from interface recombination/tunneling to depletion region recombination, suggesting a decrease in the density and dominance of interface states due to the CdCl2 treatment. It is shown that the change in transport mechanism is associated with (a) an increase in heterojunction barrier height from 0.56 to 0.85 eV, (b) a decrease in dark leakage current from 4.7×10-7 A/cm2 to 2.6×10-9 A/cm2 and, (c) an increase in cell Voc from 385 to 720 mV. The CdCl2 also improved the optical response of the cell. Substantial increases in the surface photovoltage and quantum efficiency accompanied by a decrease in the bias dependence of the spectral response in the CdCl2-treated structures indicate that the CdCl2 treatment improves carrier collection from the bulk as well as across the heterointerface. However, deep level transient spectroscopy measurements detected a hole trap within the CdTe depletion region of the CdCl2-treated devices at Ev + 0.64 eV which is attributed to the formation of VCd-related defects during the annealing process after the CdCl2 dip. J-V-T analysis demonstrated that this trap is the probable source of dominant recombination in the CdCl2-treated cells. An inverse correlation was found between the density of the Ev + 0.64 eV trap and cell Voc, suggesting that the heat treatment with CdCl2 may eventually limit the CdTe/CdS cell performance unless the

  13. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  14. Optimization of p-GaN/InGaN/n-GaN Double Heterojunction p-i-n Solar Cell for High Efficiency: Simulation Approach

    Directory of Open Access Journals (Sweden)

    Aniruddha Singh Kushwaha

    2014-01-01

    Full Text Available We have conducted numerical simulation of p-GaN/In0.12Ga0.88N/n-GaN, p-i-n double heterojunction solar cell. The doping density, individual layer thickness, and contact pattern of the device are investigated under solar irradiance of AM1.5 for optimized performance of solar cell. The optimized solar cell characteristic parameters for cell area of 1  × 1 mm2 are open circuit voltage of 2.26 V, short circuit current density of 3.31 mA/cm2, fill factor of 84.6%, and efficiency of 6.43% with interdigitated grid pattern.

  15. Formamidinium lead trihalide: a broadly tunable perovskite for efficient planar heterojunction solar cells

    OpenAIRE

    Eperon, GE; Stranks, SD; Menelaou, C.; Johnston, MB; Herz, LM; Snaith, HJ

    2014-01-01

    Perovskite-based solar cells have attracted significant recent interest, with power conversion efficiencies in excess of 15% already superceding a number of established thin-film solar cell technologies. Most work has focused on a methylammonium lead trihalide perovskites, with a bandgaps of ∼1.55 eV and greater. Here, we explore the effect of replacing the methylammonium cation in this perovskite, and show that with the slightly larger formamidinium cation, we can synthesise formamidinium le...

  16. Power Spectral Density of Fluctuations of Bulk and Thermal Speeds in the Solar Wind

    Science.gov (United States)

    Šafránková, J.; Němeček, Z.; Němec, F.; Přech, L.; Chen, C. H. K.; Zastenker, G. N.

    2016-07-01

    This paper analyzes solar wind power spectra of bulk and thermal speed fluctuations that are computed with a time resolution of 32 ms in the frequency range of 0.001–2 Hz. The analysis uses measurements of the Bright Monitor of the Solar Wind on board the Spektr-R spacecraft that are limited to 570 km s‑1 bulk speed. The statistics, based on more than 42,000 individual spectra, show that: (1) the spectra of bulk and thermal speeds can be fitted by two power-law segments; (2) despite their large variations, the parameters characterizing frequency spectrum fits computed on each particular time interval are very similar for both quantities; (3) the median slopes of the bulk and thermal speeds of the segment attributed to the MHD scale are ‑1.43 and ‑1.38, respectively, whereas they are ‑3.08 and ‑2.43 in the kinetic range; (4) the kinetic range slopes of bulk and thermal speed spectra become equal when either the ion density or magnetic field strength are high; (5) the break between MHD and kinetic scales seems to be controlled by the ion β parameter; (6) the best scaling parameter for bulk and thermal speed variations is a sum of the inertial length and proton thermal gyroradius; and (7) the above conclusions can be applied to the density variations if the background magnetic field is very low.

  17. Using a low-temperature carbon electrode for preparing hole-conductor-free perovskite heterojunction solar cells under high relative humidity

    Science.gov (United States)

    Liu, Zhiyong; Shi, Tielin; Tang, Zirong; Sun, Bo; Liao, Guanglan

    2016-03-01

    We demonstrate the application of a low-temperature carbon counter electrode with good flexibility and high conductivity in fabricating perovskite solar cells. A modified two-step method was used for the deposition of nanocrystalline CH3NH3PbI3 under high relative humidity. The carbon counter electrode was printed on a perovskite layer directly, with different sizes of graphite powder being employed. The interfacial charge transfer and transport in solar cells were investigated through photoluminescence and impedance measurements. We find that the existence of nano-graphite powder in the electrode has a noticeable influence on the back contact and cell performance. The prepared devices of hole-conductor-free perovskite heterojunction solar cells without encapsulation exhibit advantageous stability in air in the dark, with the optimal power conversion efficiency reaching 6.88%. This carbon counter electrode has the features of low-cost and low-temperature preparation, giving it potential for application in the large-scale flexible fabrication of perovskite solar cells in the future.We demonstrate the application of a low-temperature carbon counter electrode with good flexibility and high conductivity in fabricating perovskite solar cells. A modified two-step method was used for the deposition of nanocrystalline CH3NH3PbI3 under high relative humidity. The carbon counter electrode was printed on a perovskite layer directly, with different sizes of graphite powder being employed. The interfacial charge transfer and transport in solar cells were investigated through photoluminescence and impedance measurements. We find that the existence of nano-graphite powder in the electrode has a noticeable influence on the back contact and cell performance. The prepared devices of hole-conductor-free perovskite heterojunction solar cells without encapsulation exhibit advantageous stability in air in the dark, with the optimal power conversion efficiency reaching 6.88%. This carbon

  18. Theoretical maximum efficiency of solar energy conversion in plasmonic metal-semiconductor heterojunctions.

    Science.gov (United States)

    Cushing, Scott K; Bristow, Alan D; Wu, Nianqiang

    2015-11-28

    Plasmonics can enhance solar energy conversion in semiconductors by light trapping, hot electron transfer, and plasmon-induced resonance energy transfer (PIRET). The multifaceted response of the plasmon and multiple interaction pathways with the semiconductor makes optimization challenging, hindering design of efficient plasmonic architectures. Therefore, in this paper we use a density matrix model to capture the interplay between scattering, hot electrons, and dipole-dipole coupling through the plasmon's dephasing, including both the coherent and incoherent dynamics necessary for interactions on the plasmon's timescale. The model is extended to Shockley-Queisser limit calculations for both photovoltaics and solar-to-chemical conversion, revealing the optimal application of each enhancement mechanism based on plasmon energy, semiconductor energy, and plasmon dephasing. The results guide application of plasmonic solar-energy harvesting, showing which enhancement mechanism is most appropriate for a given semiconductor's weakness, and what nanostructures can achieve the maximum enhancement.

  19. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    OpenAIRE

    Martí, A.; De Luque, A.

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base–emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers th...

  20. Three-terminal heterojunction bipolar transistor solar cell for high-efficiency photovoltaic conversion

    OpenAIRE

    Martí Vega, Antonio; Luque López, Antonio

    2015-01-01

    Here we propose, for the first time, a solar cell characterized by a semiconductor transistor structure (n/p/n or p/n/p) where the base-emitter junction is made of a high-bandgap semiconductor and the collector is made of a low-bandgap semiconductor. We calculate its detailed-balance efficiency limit and prove that it is the same one than that of a double-junction solar cell. The practical importance of this result relies on the simplicity of the structure that reduces the number of layers th...

  1. Core/Shell heterojunction nanowire solar cell fabricated by lithographically patterned nanowire electrodeposition method

    OpenAIRE

    Ghosh, Somnath

    2012-01-01

    Lithographically Patterned NW Electrodeposition (LPNE) is a new technique for preparing NWs that was developed by Prof. Erik Menke while he was doing his research in Penner group in 2006. Here, we discuss some of the common problems in state of the art solar cell technology and how we can effectively use LPNE to make next generation Core/Shell NW based solar cells and NIR photodetectors. The first step in the process is the synthesis of Au/PbSe and Au/copper indium diselenide (CIS) core/shell...

  2. Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO.

    Science.gov (United States)

    Ievskaya, Yulia; Hoye, Robert L Z; Sadhanala, Aditya; Musselman, Kevin P; MacManus-Driscoll, Judith L

    2016-01-01

    Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics. PMID:27500923

  3. High-performance inverted planar heterojunction perovskite solar cells based on a solution-processed CuOx hole transport layer

    Science.gov (United States)

    Sun, Weihai; Li, Yunlong; Ye, Senyun; Rao, Haixia; Yan, Weibo; Peng, Haitao; Li, Yu; Liu, Zhiwei; Wang, Shufeng; Chen, Zhijian; Xiao, Lixin; Bian, Zuqiang; Huang, Chunhui

    2016-05-01

    During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid (PEDOT:PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT:PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (Voc) of 0.99 V, a short-circuit current (Jsc) of 23.2 mA cm-2 and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PEDOT:PSS layer, indicating that CuOx could be a promising HTM for replacing PEDOT:PSS in inverted planar heterojunction perovskite solar cells.During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid (PEDOT:PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT:PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a

  4. Efficient perovskite solar cells based on low-temperature solution-processed (CH3NH3)PbI3 perovskite/CuInS2 planar heterojunctions

    OpenAIRE

    CHEN Chong; Li, Chunxi; Li, Fumin; Wu, Fan; Tan, Furui; Zhai, Yong; Zhang, Weifeng

    2014-01-01

    In this work, the solution-processed CH3NH3PbI3 perovskite/copper indium disulfide (CuInS2) planar heterojunction solar cells with Al2O3 as a scaffold were fabricated at a temperature as low as 250°C for the first time, in which the indium tin oxide (ITO)-coated glass instead of the fluorine-doped tin oxide (FTO)-coated glass was used as the light-incidence electrode and the solution-processed CuInS2 layer was prepared to replace the commonly used TiO2 layer in previously reported perovskite-...

  5. High-performance solar-blind ultraviolet photodetector based on electrospun TiO2-ZnTiO3 heterojunction nano- wires

    Institute of Scientific and Technical Information of China (English)

    Haining Chong[1,2; Guodong Wei[2; Huilin Hou[2; Huijun Yang[1; Minghui Shang[2; Fengmei Gao[2; Weiyou Yang[2; Guozhen Shen[3

    2015-01-01

    High-performance solar-blind UV (ultraviolet) photodetectors (PDs) based on low-dimension semiconducting nanostructures with high sensitivity, excellent cycle stability, and the ability to operate in harsh environments are critical for solar observations, space communication, UV astronomy, and missile tracking. In this study, TiO2-ZnTiO3 heterojunction nanowire-based PDs are successfully developed and used to detect solar-blind UV light. A photoconductive analysis indicates that the fabricated PDs are sensitive to UV illumination, with high sensitivity, good stability, and high reproducibility. Further analysis indicates that the rich existence of grain boundaries within the TiO2-ZnTiO3 nanowire can greatly decrease the dark current and recombination of the electron-hole pairs and thereby significantly increase the device's photosensitivity, spectra responsivity (1.1 ~ 106), and external quantum efficiency (4.3 ~ 108 %). Moreover, the PDs exhibit good photodetective performance with fast photoresponse and recovery and excellent thermal stability at temperatures as high as 175 ℃. According to these results, TiO2-ZnTiO3 heterojunction nanowires exhibit great potential for applications in high-performance optical electronics and PDs, particularly next-generation photodetectors with the ability to operate in harsh environments.

  6. Yttrium-substituted nanocrystalline TiO 2 photoanodes for perovskite based heterojunction solar cells

    KAUST Repository

    Qin, Peng

    2014-01-01

    We report the use of Y3+-substituted TiO2 (0.5%Y-TiO2) in solid-state mesoscopic solar cells, consisting of CH3NH3PbI3 as the light harvester and spiro-OMeTAD as the hole transport material. A power conversion efficiency of 11.2% under simulated AM 1.5 full sun illumination was measured. A 15% improvement in the short-circuit current density was obtained compared with pure TiO2, due to the effect of Y3+ on the dimensions of perovskite nanoparticles formed on the semiconductor surface, showing that the surface modification of the semiconductor is an effective way to improve the light harvesters\\' morphology and electron transfer properties in the solid-state mesoscopic solar cells. © 2013 The Royal Society of Chemistry.

  7. A way for studying the impact of PEDOT:PSS interface layer on carrier transport in PCDTBT:PC{sub 71}BM bulk hetero junction solar cells by electric field induced optical second harmonic generation measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Zubair, E-mail: zubairtarar@um.edu.my; Abdullah, Shahino Mah; Sulaiman, Khaulah [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Taguchi, Dai; Iwamoto, Mitsumasa [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2015-04-28

    Electric-field-induced optical second-harmonic generation (EFISHG) measurement was employed to study the impact of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) interface layer on the carrier transport mechanism of the PCDTBT:PC{sub 71}BM bulk heterojunction (BHJ) organic solar cells (OSCs). We revealed that the electric fields in the PCDTBT and PC{sub 71}BM were allowed to be measured individually by choosing fundamental laser wavelengths of 1000 nm and 1060 nm, respectively, in dark and under illumination. The results showed that the direction of the internal electric fields in the PCDTBT:PC{sub 71}BM BHJ layer is reversed by introducing the PEDOT:PSS layer, and this results in longer electron transport time in the BHJ layer. We conclude that TR-EFISHG can be used as a novel way for studying the impact of interfacial layer on the transport of electrons and holes in the bulk-heterojunction OSCs.

  8. Minority carrier transport length in electrodeposited Cu2O for heterojunction solar cells

    Science.gov (United States)

    Liu, Yingchi; Turley, Hubert K.; Tumbleston, John R.; Lopez, Rene

    2011-09-01

    The minority carrier transport length (L) is a critical parameter limiting the performance of inexpensive Cu2O-ZnO photovoltaic devices. In this work, this length is determined for electrochemically deposited Cu2O by linking the optical carrier generation profile from front and back incident-photon-to-electron conversion efficiency (IPCE) measurements to a one dimensional carrier transport model. A transport length of ~ 400 nm is estimated. This critical length explains the losses typically presented by these devices. The consequences of this L on device design with the aim of improving solar cell performance are described.

  9. Photovoltaic characteristics of diffused P/+N bulk GaAs solar cells

    Science.gov (United States)

    Borrego, J. M.; Keeney, R. P.; Bhat, I. B.; Bhat, K. N.; Sundaram, L. G.; Ghandhi, S. K.

    1982-01-01

    The photovoltaic characteristics of P(+)N junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are described in this paper.Spectral response measurements were analyzed in detail and compared to a computer simulation in order to determine important material parameters. It is projected that proper optimization of the cell parameters can increase the efficiency of the cells from 12.2 percent to close to 20 percent.

  10. Electrodeposited copper front metallization for silicon heterojunction solar cells: materials and processes

    Energy Technology Data Exchange (ETDEWEB)

    Geissbühler, J.; Martin de Nicolas, S.; Faes, A.; Lachowicz, A.; Tomasi, A.; Paviet-Salomon, B.; Lachenal, D.; Papet, P.; Badel, N.; Barraud, L.; Descoeudres, A.; Despeisse, M.; De Wolf, S.; Ballif, C.

    2014-10-20

    Even though screen-printing of low-temperature silver paste remains the state-of-the-art technique for the front-metallization of SHJ solar cells, recent studies have demonstrated large efficiency improvements when copper-electroplated contacts are used instead of screen-printed ones. However, due to the new materials and the new processes introduced by this technique, it is crucial to individually investigate their compatibility with the SHJ cell structure. In this study, we present a detailed analysis of how the performances of SHJ devices may be modified by these new materials and processes. First, effects on the amorphous silicon (a-Si:H) passivation have been studied for various processes such as DI water rinsing, dips in a copper removal solution and direct evaporation of copper on the a-Si:H. Finally, copper electroplating technique has been adapted in order to be applied to more complex cell structures such as high-efficiency IBC-SHJ.

  11. A numerical simulation study of gallium-phosphide/silicon heterojunction passivated emitter and rear solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Hannes [Department of Solar Energy, Institute Solid-State Physics, Leibniz University of Hannover, Appelstr. 2, 30167 Hannover (Germany); ARC Photovoltaics Centre of Excellence, University of New South Wales (UNSW), Sydney, NSW 2052 (Australia); Ohrdes, Tobias [Institute for Solar Energy Research Hamelin (ISFH), 31860 Emmerthal (Germany); Dastgheib-Shirazi, Amir [Div. Photovoltaics, Department of Physics, University of Konstanz, 78457 Konstanz (Germany); Puthen-Veettil, Binesh; König, Dirk [ARC Photovoltaics Centre of Excellence, University of New South Wales (UNSW), Sydney, NSW 2052 (Australia); Altermatt, Pietro P. [Department of Solar Energy, Institute Solid-State Physics, Leibniz University of Hannover, Appelstr. 2, 30167 Hannover (Germany)

    2014-01-28

    The performance of passivated emitter and rear (PERC) solar cells made of p-type Si wafers is often limited by recombination in the phosphorus-doped emitter. To overcome this limitation, a realistic PERC solar cell is simulated, whereby the conventional phosphorus-doped emitter is replaced by a thin, crystalline gallium phosphide (GaP) layer. The resulting GaP/Si PERC cell is compared to Si PERC cells, which have (i) a standard POCl{sub 3} diffused emitter, (ii) a solid-state diffused emitter, or (iii) a high efficiency ion-implanted emitter. The maximum efficiencies for these realistic PERC cells are between 20.5% and 21.2% for the phosphorus-doped emitters (i)–(iii), and up to 21.6% for the GaP emitter. The major advantage of this GaP hetero-emitter is a significantly reduced recombination loss, resulting in a higher V{sub oc}. This is so because the high valence band offset between GaP and Si acts as a nearly ideal minority carrier blocker. This effect is comparable to amorphous Si. However, the GaP layer can be contacted with metal fingers like crystalline Si, so no conductive oxide is necessary. Compared to the conventional PERC structure, the GaP/Si PERC cell requires a lower Si base doping density, which reduces the impact of the boron-oxygen complexes. Despite the lower base doping, fewer rear local contacts are necessary. This is so because the GaP emitter shows reduced recombination, leading to a higher minority electron density in the base and, in turn, to a higher base conductivity.

  12. A numerical simulation study of gallium-phosphide/silicon heterojunction passivated emitter and rear solar cells

    Science.gov (United States)

    Wagner, Hannes; Ohrdes, Tobias; Dastgheib-Shirazi, Amir; Puthen-Veettil, Binesh; König, Dirk; Altermatt, Pietro P.

    2014-01-01

    The performance of passivated emitter and rear (PERC) solar cells made of p-type Si wafers is often limited by recombination in the phosphorus-doped emitter. To overcome this limitation, a realistic PERC solar cell is simulated, whereby the conventional phosphorus-doped emitter is replaced by a thin, crystalline gallium phosphide (GaP) layer. The resulting GaP/Si PERC cell is compared to Si PERC cells, which have (i) a standard POCl3 diffused emitter, (ii) a solid-state diffused emitter, or (iii) a high efficiency ion-implanted emitter. The maximum efficiencies for these realistic PERC cells are between 20.5% and 21.2% for the phosphorus-doped emitters (i)-(iii), and up to 21.6% for the GaP emitter. The major advantage of this GaP hetero-emitter is a significantly reduced recombination loss, resulting in a higher Voc. This is so because the high valence band offset between GaP and Si acts as a nearly ideal minority carrier blocker. This effect is comparable to amorphous Si. However, the GaP layer can be contacted with metal fingers like crystalline Si, so no conductive oxide is necessary. Compared to the conventional PERC structure, the GaP/Si PERC cell requires a lower Si base doping density, which reduces the impact of the boron-oxygen complexes. Despite the lower base doping, fewer rear local contacts are necessary. This is so because the GaP emitter shows reduced recombination, leading to a higher minority electron density in the base and, in turn, to a higher base conductivity.

  13. Correlation between the fine structure of spin-coated PEDOT:PSS and the photovoltaic performance of organic/crystalline-silicon heterojunction solar cells

    Science.gov (United States)

    Funda, Shuji; Ohki, Tatsuya; Liu, Qiming; Hossain, Jaker; Ishimaru, Yoshihiro; Ueno, Keiji; Shirai, Hajime

    2016-07-01

    We investigated the relationship between the fine structure of spin-coated conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrene sulfonate) (PEDOT:PSS) films and the photovoltaic performance of PEDOT:PSS crystalline-Si (PEDOT:PSS/c-Si) heterojunction solar cells. Real-time spectroscopic ellipsometry revealed that there were two different time constants for the formation of the PEDOT:PSS network. Upon removal of the polar solvent, the PEDOT:PSS film became optically anisotropic, indicating a conformational change in the PEDOT and PSS chain. Polarized Fourier transform infrared attenuated total reflection absorption spectroscopy and Raman spectroscopy measurements also indicated that thermal annealing promoted an in-plane π-conjugated Cα = Cβ configuration attributed to a thiophene ring in PEDOT and an out-of-plane configuration of -SO3 groups in the PSS chain with increasing composition ratio of oxidized (benzoid) to neutral (quinoid) PEDOT, Iqui/Iben. The highest power conversion efficiency for the spin-coated PEDOT:PSS/c-Si heterojunction solar cells was 13.3% for Iqui/Iben = 9-10 without employing any light harvesting methods.

  14. Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

    Science.gov (United States)

    Xu, Xiaojie; Bullock, James; Schelhas, Laura T; Stutz, Elias Z; Fonseca, Jose J; Hettick, Mark; Pool, Vanessa L; Tai, Kong Fai; Toney, Michael F; Fang, Xiaosheng; Javey, Ali; Wong, Lydia Helena; Ager, Joel W

    2016-03-01

    P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV). PMID:26855162

  15. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    internal quantum efficiency shows that both types of back contacts lead to effective diffusion lengths in excess of 600 {mu}m. An extended fill factor analysis shows that fill factor limitations for the full-area a-Si:H/c-Si contacts result from non-ideal diode behavior, ascribed to the injection dependence of the heterojunction interface recombination velocity. Analysis of the external quantum efficiency under back side illumination with different bias light intensities delivers the effective surface recombination S{sub eff}({phi}) in dependance of the illumination intensity {phi}. The front contact (emitter) uses a sequence of intrinsic and phosphorous doped amorphous silicon layers together with a ZnO:Al or a SnO{sub 2}:In layer and an Al front contact grid. The emitter is prepared at a maximum temperature of 220 C. Measurements of the minority carrier lifetime on symmetric i/n-a-Si:H coated wafers judge the emitter passivation quality. The best solar cells that use a thermal oxide back side passivation with Al-point contacts and flat a-Si:H emitters have open circuit voltages up to 683 mV and efficiencies up to 17.4 %. The efficiency of such devices is limited by a low short circuit current due to the flat front side. Using the same back contact structure with random pyramid textured wafer front sides and a-Si:H emitters yields open circuit voltages up to 660 mV and efficiencies up to 18.5 %, so far limited by a relatively low fill factor FF {<=} 74.3 %. Analysis of the external quantum efficiency underlines the excellent surface passivation properties of the amorphous emitter. Combining both, amorphous front- and back contacts yields p-type heterojunction solar cells completely fabricated at temperatures below 220 C. The best devices reach an open circuit voltage V{sub oc} = 678 mV and an efficiency {eta} = 18.1 % with random textured wafers, limited by low fill factors FF {approx} 75 %. Besides the cell fabrication and characterization, this thesis reveals that the

  16. Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers

    Directory of Open Access Journals (Sweden)

    Tetsuro Hori

    2010-11-01

    Full Text Available Organic thin-film solar cells with a conducting polymer (CP/fullerene (C60 interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/ poly(3-hexylthiophene (PAT6/Au have been improved by the insertion of molybdenum trioxide (VI (MoO3 and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers.

  17. AC characterization of bulk organic solar cell in the dark and under illumination

    International Nuclear Information System (INIS)

    Highlights: • A study of organic bulk photovoltaic (PV) solar cell. • Current–voltage characteristics in the dark and under illumination. • AC measurements, both under illumination and in the dark conditions. • Equivalent AC circuit. • Effective lifetime assigned with electron–hole recombination and diffusion time of the electron was estimated. - Abstract: Impedance spectroscopy has been used widely to evaluate the transport processes in photovoltaic, mainly based on inorganic semiconductors, structures – solar cells. The aim of this research was to characterize improved organic bulk photovoltaic (PV) solar cells exploiting this method. Progress in technology of investigated organic solar cell involves the use of an active layer based on low band gap type of polymer. The organic PV cell with front transparent electrode and rear metal electrode and active layer produced by Konarka Technologies was analyzed by electrical DC and AC measurements. Current–voltage (I–V) characteristics in the dark and under illumination were measured and basic PV parameters were calculated. AC measurements, both under illumination and in the dark conditions, were processed in order to identify electronic behavior using equivalent AC circuit which was suggested by fitting of measured impedance data. Circuit with the best correlation to measured data is analyzed in details. Voltage and frequency dependences of fitted equivalent circuit components and calculated parameters are explained and presented in the paper

  18. Optimization and degradation of rubrene/C70 heterojunction solar cells

    Institute of Scientific and Technical Information of China (English)

    CHEN Zi-guo; LIU Peng-yi; HOU Lin-tao; MAI Wen-jie; WU Bing

    2012-01-01

    Small molecule organic solar cells (OSCs) with the structure of indium tin oxide (ITO)/molybdenum trioxide (MoO3) (5nm)/rubrene (x nm)/fullerene (C70) (y nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) (6 nm)/aluminum (Al)(150 nm) are fabricated.The thickness of active layer for the devices is investigated in details.The results show that the optimum thicknesses of rubrene layer and C70 layer are 30 nm and 25 nm,respectively.The degradation of the device is also investigated.The result indicates that the open-circuit voltage (Voc) does not change,while the short-circuit current density (Jsc),fill factor (FF) and power conversion efficiency (PCE) decrease continuously with time.The degradation can be attributed to the oxygen in ambient diffusing and infiltrating into the active materials and reacting with C70 in cells,which can result in the increase of interfacial series resistance.

  19. Heterojunction properties of electrodeposited CdTe/CdS solar cells

    Science.gov (United States)

    Rakhshani, A. E.

    2001-10-01

    Solar cells of p-CdTe/n-CdS structure with a conversion efficiency of 10%±1% (AM1 spectrum, 127 mW/cm2 irradiance) were prepared by electrodeposition of CdTe on CdS-coated conducting glass. CdS was coated by chemical bath deposition. The tin-oxide conducting glass was prepared by the spray pyrolysis technique. The current-voltage, capacitance-voltage, photocurrent-voltage, photocurrent spectroscopy, and photoinduced current transient spectroscopy measurements proved to be powerful tools for the characterization of junction. The concentration of donors and acceptors in both sides of the junction are comparable, in the range of 1016cm-3. The cell built-in potential is 1.20 V from which 0.65 V drops across the depletion width of CdTe. From the analysis of experimental data to construct the energy band diagram, it becomes evident that an electric dipole layer must exist at the CdTe/CdS interface. The presence of this layer is associated with a discontinuity of electrostatic potential at the interface by 0.28 V and a conduction-band spike of 64 meV. The conduction-band spike and an interfacial recombination center are accountable for the collection losses of photogenerated carriers. The recombination center that is likely related to the interstitial cadmium defect is energetically located 0.63 eV below the conduction-band edge and has a capture cross section of 8.8×10-12 cm2. 2001 American Institute of Physics.

  20. Towards optical optimization of planar monolithic perovskite/silicon-heterojunction tandem solar cells

    Science.gov (United States)

    Albrecht, Steve; Saliba, Michael; Correa-Baena, Juan-Pablo; Jäger, Klaus; Korte, Lars; Hagfeldt, Anders; Grätzel, Michael; Rech, Bernd

    2016-06-01

    Combining inorganic–organic perovskites and crystalline silicon into a monolithic tandem solar cell has recently attracted increased attention due to the high efficiency potential of this cell architecture. Promising results with published efficiencies above 21% have been reported so far. To further increase the device performance, optical optimizations enabling device related guidelines are highly necessary. Here we experimentally show the optical influence of the ITO thickness in the interconnecting layer and fabricate an efficient monolithic tandem cell with a reduced ITO layer thickness that shows slightly improved absorption within the silicon sub-cell and a stabilized power output of 17%. Furthermore we present detailed optical simulations on experimentally relevant planar tandem stacks to give practical guidelines to reach efficiencies above 25%. By optimizing the thickness of all functional and the perovskite absorber layers, together with the optimization of the perovskite band-gap, we present a tandem stack that can yield ca 17.5 mA cm‑ 2 current in both sub-cells at a perovskite band-gap of 1.73 eV including losses from reflection and parasitic absorption. Assuming that the higher band-gap of the perovskite absorber directly translates into a higher open circuit voltage, the perovskite sub-cell should be able to reach a value of 1.3 V. With that, realistic efficiencies above 28% are within reach for planar monolithic tandem cells in which the thickness of the perovskite top-cell and the perovskite band-gap are highly optimized. When applying light trapping schemes such as textured surfaces and by reducing the parasitic absorption of the functional layers, for example in spiro-OMeTAD, this monolithic tandem can overcome 30% power conversion efficiency.

  1. Highly Efficient Conjugated Polymer/Fulleren Solar Cells

    Science.gov (United States)

    Brabec, Christoph J.

    2001-03-01

    The increase of mobility of hole conducting polmyers upon different processing is also reflected in the improved performance of photovoltaic bulk heterojunction cells, in our case, based on organic blends of MDMO-PPV and [6,6]PCBM. The field-effect hole mobilities of pristine MDMO-PPV have been measured to be 4.8 * 10-6 cm2/Vs and 3.3 * 10-5 cm2/Vs respectively, depending on the solvent-induced modification of the polymer morphology. The performance of such "bulk heterojunction" photovoltaic devices is further critically depending on the formation of the interpenetrating network between the fullerene and the polymer. We discuss the optimization of the photocurrent in thin bulk heterojunctions solar cells where the diffusion/drift lengths are in the order of the device thickness. Solar cells with a power efficiency higher than 2.5illumination and an external quantum efficiency higher than 50

  2. Low temperature surface passivation of crystalline silicon and its application to interdigitated back contact silicon heterojunction (ibc-shj) solar cell

    Science.gov (United States)

    Shu, Zhan

    With the absence of shading loss together with improved quality of surface passivation introduced by low temperature processed amorphous silicon crystalline silicon (a-Si:H/c-Si) heterojunction, the interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell exhibits a potential for higher conversion efficiency and lower cost than a traditional front contact diffused junction solar cell. In such solar cells, the front surface passivation is of great importance to achieve both high open-circuit voltage (Voc) and short-circuit current (Jsc). Therefore, the motivation of this work is to develop a low temperature processed structure for the front surface passivation of IBC-SHJ solar cells, which must have an excellent and stable passivation quality as well as a good anti-reflection property. Four different thin film materials/structures were studied and evaluated for this purpose, namely: amorphous silicon nitride (a-SiNx:H), thick amorphous silicon film (a-Si:H), amorphous silicon/silicon nitride/silicon carbide (a-Si:H/a-SiN x:H/a-SiC:H) stack structure with an ultra-thin a-Si:H layer, and zinc sulfide (ZnS). It was demonstrated that the a-Si:H/a-SiNx:H/a-SiC:H stack surpasses other candidates due to both of its excellent surface passivation quality (SRV<5 cm/s) and lower absorption losses. The low recombination rate at the stack structure passivated c-Si surface is found to be resulted from (i) field effect passivation due to the positive fixed charge (Q fix~1x1011 cm-2 with 5 nm a-Si:H layer) in a-SiNx:H as measured from capacitance-voltage technique, and (ii) reduced defect state density (mid-gap Dit~4x1010 cm-2eV-1) at a-Si:H/c-Si interface provided by a 5 nm thick a-Si:H layer, as characterized by conductance-frequency measurements. Paralleled with the experimental studies, a computer program was developed in this work based on the extended Shockley-Read-Hall (SRH) model of surface recombination. With the help of this program, the experimental

  3. Using a low-temperature carbon electrode for preparing hole-conductor-free perovskite heterojunction solar cells under high relative humidity.

    Science.gov (United States)

    Liu, Zhiyong; Shi, Tielin; Tang, Zirong; Sun, Bo; Liao, Guanglan

    2016-04-01

    We demonstrate the application of a low-temperature carbon counter electrode with good flexibility and high conductivity in fabricating perovskite solar cells. A modified two-step method was used for the deposition of nanocrystalline CH3NH3PbI3 under high relative humidity. The carbon counter electrode was printed on a perovskite layer directly, with different sizes of graphite powder being employed. The interfacial charge transfer and transport in solar cells were investigated through photoluminescence and impedance measurements. We find that the existence of nano-graphite powder in the electrode has a noticeable influence on the back contact and cell performance. The prepared devices of hole-conductor-free perovskite heterojunction solar cells without encapsulation exhibit advantageous stability in air in the dark, with the optimal power conversion efficiency reaching 6.88%. This carbon counter electrode has the features of low-cost and low-temperature preparation, giving it potential for application in the large-scale flexible fabrication of perovskite solar cells in the future. PMID:26660267

  4. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Taweewat Krajangsang

    2014-01-01

    Full Text Available Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage (Voc, fill factor (FF, and temperature coefficient (TC of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5% (Voc=700 mV, Jsc=33.5 mA/cm2, and FF=0.79. The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C.

  5. Influence of air exposure duration and a-Si capping layer thickness on the performance of p-BaSi2/n-Si heterojunction solar cells

    Science.gov (United States)

    Takabe, Ryota; Yachi, Suguru; Du, Weijie; Tsukahara, Daichi; Takeuchi, Hiroki; Toko, Kaoru; Suemasu, Takashi

    2016-08-01

    Fabrication of p-BaSi2(20nm)/n-Si heterojunction solar cells was performed with different a-Si capping layer thicknesses (da-Si) and varying air exposure durations (tair) prior to the formation of a 70-nm-thick indium-tin-oxide electrode. The conversion efficiencies (η) reached approximately 4.7% regardless of tair (varying from 12-150 h) for solar cells with da-Si = 5 nm. In contrast, η increased from 5.3 to 6.6% with increasing tair for those with da-Si = 2 nm, in contrast to our prediction. For this sample, the reverse saturation current density (J0) and diode ideality factor decreased with tair, resulting in the enhancement of η. The effects of the variation of da-Si (0.7, 2, 3, and 5 nm) upon the solar cell performance were examined while keeping tair = 150 h. The η reached a maximum of 9.0% when da-Si was 3 nm, wherein the open-circuit voltage and fill factor also reached a maximum. The series resistance, shunt resistance, and J0 exhibited a tendency to decrease as da-Si increased. These results demonstrate that a moderate oxidation of BaSi2 is a very effective means to enhance the η of BaSi2 solar cells.

  6. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    International Nuclear Information System (INIS)

    Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C), which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ∼150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene)/Ag architecture

  7. Nanostructured TiO2/CH3NH3PbI3 heterojunction solar cells employing spiro-OMeTAD/Co-complex as hole-transporting material

    KAUST Repository

    Noh, Jun Hong

    2013-01-01

    For using 2,2′,7,7′-tetrakis(N,N′-di-p- methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a hole conductor in solar cells, it is necessary to improve its charge-transport properties through electrochemical doping. With the aim of fabricating efficient mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cells, we used tris[2-(1H-pyrazol-1-yl)-4-tert- butylpyridine)cobalt(iii) tris(bis(trifluoromethylsulfonyl) imide)] (FK209) as a p-dopant for spiro-OMeTAD. The mixture of spiro-OMeTAD, FK209, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI), and 4-tert-butylpyridine (TBP) exhibited significantly higher performance than mixtures of pristine spiro-OMeTAD, spiro-OMeTAD, and FK209, and spiro-OMeTAD, Li-TFSI, and TBP. Such a synergistic effect between the Co-complex and Li-TFSI in conjunction with spiro-OMeTAD effectively improved the power conversion efficiency (PCE) of the fabricated solar cells. As a result, we achieved PCE of 10.4%, measured under standard solar conditions (AM 1.5G, 100 mW cm-2). © 2013 The Royal Society of Chemistry.

  8. An easy-to-fabricate low-temperature TiO{sub 2} electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Conings, B.; Baeten, L.; Jacobs, T.; Dera, R.; D’Haen, J.; Manca, J.; Boyen, H.-G. [Instituut voor Materiaalonderzoek, Universiteit Hasselt, Wetenschapspark 1, 3590 Diepenbeek (Belgium)

    2014-08-01

    Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO{sub 2} electron collection layer that requires a high temperature treatment (>450 °C), which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ∼150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO{sub 2} layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO{sub 2} layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO{sub 2}/CH{sub 3}NH{sub 3}PbI{sub 3-x}Cl{sub x}poly(3-hexylthiophene)/Ag architecture.

  9. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Science.gov (United States)

    Conings, B.; Baeten, L.; Jacobs, T.; Dera, R.; D'Haen, J.; Manca, J.; Boyen, H.-G.

    2014-08-01

    Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C), which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ˜150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene)/Ag architecture.

  10. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells

    Directory of Open Access Journals (Sweden)

    B. Conings

    2014-08-01

    Full Text Available Organometal trihalide perovskite solar cells arguably represent the most auspicious new photovoltaic technology so far, as they possess an astonishing combination of properties. The impressive and brisk advances achieved so far bring forth highly efficient and solution processable solar cells, holding great promise to grow into a mature technology that is ready to be embedded on a large scale. However, the vast majority of state-of-the-art perovskite solar cells contains a dense TiO2 electron collection layer that requires a high temperature treatment (>450 °C, which obstructs the road towards roll-to-roll processing on flexible foils that can withstand no more than ∼150 °C. Furthermore, this high temperature treatment leads to an overall increased energy payback time and cumulative energy demand for this emerging photovoltaic technology. Here we present the implementation of an alternative TiO2 layer formed from an easily prepared nanoparticle dispersion, with annealing needs well within reach of roll-to-roll processing, making this technology also appealing from the energy payback aspect. Chemical and morphological analysis allows to understand and optimize the processing conditions of the TiO2 layer, finally resulting in a maximum obtained efficiency of 13.6% for a planar heterojunction solar cell within an ITO/TiO2/CH3NH3PbI3-xClxpoly(3-hexylthiophene/Ag architecture.

  11. Efficient small molecule bulk heterojunction solar cells with high fill factors via pyrene-directed molecular self-assembly

    KAUST Repository

    Lee, Olivia P.

    2011-10-21

    Efficient organic photovoltaic (OPV) materials are constructed by attaching completely planar, symmetric end-groups to donor-acceptor electroactive small molecules. Appending C2-pyrene as the small molecule end-group to a diketopyrrolopyrrole core leads to materials with a tight, aligned crystal packing and favorable morphology dictated by π-π interactions, resulting in high power conversion efficiencies and high fill factors. The use of end-groups to direct molecular self-assembly is an effective strategy for designing high-performance small molecule OPV devices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Highly efficient organic tandem solar cell with a SubPc interlayer based on TAPC:C70 bulk heterojunction

    Science.gov (United States)

    Gao, Yuan; Jin, Fangming; Li, Wenlian; Su, Zisheng; Chu, Bei; Wang, Junbo; Zhao, Haifeng; Wu, Hairuo; Liu, Chengyuan; Hou, Fuhua; Lin, Tong; Song, Qiaogang

    2016-04-01

    We report a small molecule tandem organic photovoltaic (OPV) cell with a high power conversion efficiency (PCE) of 7.27%. This cell contains two subcells with an identical mixed active layer of C70:5 wt%TAPC (1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane). The performance was dramatically improved by simply inserting a thin boron subphthalocyanine chloride (SubPc) interlayer, which results in an increase of the short-circuit current and open-circuit voltage as well as a decrease of the series resistance of the tandem cell. The response of the cell only contributed from the absorption of C70. The high PCE was attributed to the high absorption efficiency of C70 and improved holes extraction efficiency at the anode due to the band bending occurs at both MoO3/SubPc and SubPc/C70:5 wt%TAPC interfaces.

  13. Comparative studies of photochemical cross-linking methods for stabilizing the bulk hetero-junction morphology in polymer solar cells

    DEFF Research Database (Denmark)

    Carlé, Jon Eggert; Andreasen, Birgitta; Tromholt, Thomas;

    2012-01-01

    We are here presenting a comparative study between four different types of functionalities for cross-linking. With relatively simple means bromine, azide, vinyl and oxetane could be incorporated into the side chains of the low band-gap polymer TQ1. Cross-linking of the polymers was achieved by UV...

  14. Peculiarity of Two Thermodynamically-Stable Morphologies and Their Impact on the Efficiency of Small Molecule Bulk Heterojunction Solar Cells

    OpenAIRE

    Nuradhika Herath; Sanjib Das; Jong K. Keum; Jiahua Zhu; Rajeev Kumar; Ivanov, Ilia N.; Sumpter, Bobby G.; James F. Browning; Kai Xiao; Gong Gu; Pooran Joshi; Sean Smith; Valeria Lauter

    2015-01-01

    Structural characteristics of the active layers in organic photovoltaic (OPV) devices play a critical role in charge generation, separation and transport. Here we report on morphology and structural control of p-DTS(FBTTh2)2:PC71BM films by means of thermal annealing and 1,8-diiodooctane (DIO) solvent additive processing, and correlate it to the device performance. By combining surface imaging with nanoscale depth-sensitive neutron reflectometry (NR) and X-ray diffraction, three-dimensional m...

  15. Peculiarity of Two Thermodynamically-Stable Morphologies and Their Impact on the Efficiency of Small Molecule Bulk Heterojunction Solar Cells.

    Science.gov (United States)

    Herath, Nuradhika; Das, Sanjib; Keum, Jong K; Zhu, Jiahua; Kumar, Rajeev; Ivanov, Ilia N; Sumpter, Bobby G; Browning, James F; Xiao, Kai; Gu, Gong; Joshi, Pooran; Smith, Sean; Lauter, Valeria

    2015-01-01

    Structural characteristics of the active layers in organic photovoltaic (OPV) devices play a critical role in charge generation, separation and transport. Here we report on morphology and structural control of p-DTS(FBTTh2)2:PC71BM films by means of thermal annealing and 1,8-diiodooctane (DIO) solvent additive processing, and correlate it to the device performance. By combining surface imaging with nanoscale depth-sensitive neutron reflectometry (NR) and X-ray diffraction, three-dimensional morphologies of the films are reconstituted with information extending length scales from nanometers to microns. DIO promotes the formation of a well-mixed donor-acceptor vertical phase morphology with a large population of small p-DTS(FBTTh2)2 nanocrystals arranged in an elongated domain network of the film, thereby enhancing the device performance. In contrast, films without DIO exhibit three-sublayer vertical phase morphology with phase separation in agglomerated domains. Our findings are supported by thermodynamic description based on the Flory-Huggins theory with quantitative evaluation of pairwise interaction parameters that explain the morphological changes resulting from thermal and solvent treatments. Our study reveals that vertical phase morphology of small-molecule based OPVs is significantly different from polymer-based systems. The significant enhancement of morphology and information obtained from theoretical modeling may aid in developing an optimized morphology to enhance device performance for OPVs. PMID:26315070

  16. Photocatalytic activities of ultra-small β-FeOOH and TiO{sub 2} heterojunction structure under simulated solar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Mahabubur, E-mail: chowdhurym@cput.ac.za; Ntiribinyange, Mary; Nyamayaro, Kudzanai; Fester, Veruscha

    2015-08-15

    Highlights: • Ultra small β-FeOOH with TiO{sub 2} in heterojunction showed good photocatalytic activity under simulated solar irradiation. • Significant improvement of photocatalytic activity compared to pristine TiO{sub 2}. • The as prepared catalyst decoloured industrial textile effluent within 30 min. - Abstract: Photocatalytic performance of β-FeOOH/TiO{sub 2} heterojunction structure, created from ultra-small β-FeOOH nanorods (2–6 nm diameter) and spherical anatase phase of TiO{sub 2} nanoparticles (∼100 nm), is reported in this study. Three different β-FeOOH mol% of (2, 5 and 10%) β-FeOOH/TiO{sub 2} composite was prepared. 5% β-FeOOH/TiO{sub 2} composite material showed the highest photocatalytic activity. XRD, high temperature XRD, FTIR, TEM, UV–vis diffuse reflectance spectra (DRS) were used to characterise the prepared catalyst. The developed catalyst showed excellent photocatalytic activity in photodegradation of methyl orange (MO) than β-FeOOH and TiO{sub 2} under simulated solar irradiation. Two commercial metal complex dyes and real textile effluent were efficiently photodegraded under identical conditions. The developed catalyst exhibited good recyclability without the need of sintering. No significant loss in efficiency was observed during the recycling cycle. These characteristics highlight the potential application of the developed photocatalyst in textile effluent treatment via photocatalysis. The enhanced photocatalytic activity was attributed to the relative energy band positions and very good electron, e{sup −} and hole, h{sup +} conduction ability of TiO{sub 2} and β-FeOOH particles respectively.

  17. Influence of n-doped μc-Si:H back surface field layer with micro growth in crystalline-amorphous silicon heterojunction solar cells.

    Science.gov (United States)

    Kim, Sangho; Dao, Vinh Ai; Shin, Chonghoon; Balaji, Nagarajan; Yi, Junsin

    2014-12-01

    The back surface field (BSF) plays an important role for the efficiency of the heterojunction intrinsic thin-film (HIT) solar cell. In this paper, the effect of thickness variation in n-type micro crystalline BSF layer was investigated by Raman and spectroscopy ellipsometry. As we increase the crystalline volume fraction (X(c)) from 6% to 59%, the open circuit voltage (V(oc)) increases from 573 to 696 mV with increase in fill factor from 59% to 71%. However, we observed that V(oc) and FF are decreased over 59% X(c) of n-type μc-Si:H BSF layer. It seems that higher X(c) micro layer include lots of defects. The quantum efficiency (QE) measurements were demonstrated on optimized thickness of n-doped micro BSF layer. In the long wavelengths region, the QE slightly increases with increasing the n-type μc-Si:H BSF layer thickness from 10 to 40 nm because of BSF effect, whereas the QE decreases when n-type μc-Si:H BSF layer thickness increases from 40 to 120 nm due to defects in the layer. The performance of heterojunction solar cell device was improved with the optimized thickness on n-doped micro BSF layer the best photo voltage parameters of the device were found to be V(oc) of 696 mV, short-circuit current density of 36.09 mA/cm2 and efficiency of 18.06% at n-doped micro BSF layer thickness of 40 nm. PMID:25971047

  18. Heterojunction of Zinc Blende/Wurtzite in Zn1-xCdxS Solid Solution for Efficient Solar Hydrogen Generation: X-ray Absorption/Diffraction Approaches.

    Science.gov (United States)

    Hsu, Ying-Ya; Suen, Nian-Tzu; Chang, Chung-Chieh; Hung, Sung-Fu; Chen, Chi-Liang; Chan, Ting-Shan; Dong, Chung-Li; Chan, Chih-Chieh; Chen, San-Yuan; Chen, Hao Ming

    2015-10-14

    In the past decade, inorganic semiconductors have been successfully demonstrated as light absorbers in efficient solar water splitting to generate chemical fuels. Pseudobinary semiconductors Zn1-xCdxS (0≤x≤1) have exhibited a superior photocatalytic reactivity of H2 production from splitting of water by artificial solar irradiation without any metal catalysts. However, most studies had revealed that the extremely high efficiency with an optimal content of Zn1-xCdxS solid solution was determined as a result of elevating the conduction band minimum (CBM) and the width of bandgap. In addition to corresponding band structure and bandgap, the local crystal structure should be taken into account as well to determine its photocatalytic performance. Herein, we demonstrated the correlations between the photocatalytic activity and structural properties that were first studied through synchrotron X-ray diffraction and X-ray absorption spectroscopy. The crystal structure transformed from zinc blende to coexisted phases of major zinc blende and minor wurtzite phases at a critical point. The heterojunction formed by coexistence of zinc blende and wurtzite phases in the Zn1-xCdxS solid solution can significantly improve the separation and migration of photoinduced electron-hole pairs. Besides, X-ray absorption spectra and UV-vis spectra revealed that the bandgap of the Zn0.45Cd0.55S sample extended into the region of visible light because of the incorporation of Cd element in the sample. These results provided a significant progress toward the realization of the photoelectrochemical mechanism in heterojunction between zinc blende and wurtzite phases, which can effectively separate the charge-carriers and further suppress their recombination to enhance the photocatalytic reactivity. PMID:26402651

  19. Fabrication of pixilated architecture large panel organic flexible solar cell by reducing bulk electrical resistance

    Science.gov (United States)

    Panag, Jasmeet Singh

    This study investigates experimentally the photovoltaic behavior and performance of a new pixilated architecture of large organic photovoltaic panels made of a large array of high-aspect ratio three-dimensional pillars surrounded by a matrix of polymer photoactive material. A least addressed problem in organic and thin-film solar cells is the high bulk resistance of cathodic and anodic layers that result in drastic reduction of currents and power conversion efficiency (PCE). For such panels to be practical and commercially competitive, this huge bulk-resistance has to be minimized as much as possible. In this study, therefore, we introduce a new novel architecture that essentially compartmentalizes large panels into smaller modules that are connected to each other in a parallel fashion. In this architecture, the metal cathode layer is applied on the top as a series of lines whereas the anodic layer is independently connected to the pixilated cells at the bottom. As a result, these modules act like independent pixel cells wherein the damage from process and operation is limited individual pixel cells. The factors considered in validating the pixilated architecture presented here consisted of effect of number of pixels on efficiency and bulk electrical resistance. In addition, the study shows that pixilated architecture offers more uniform photoactive layers, and hence better photovoltaic performance because of the compartmentalization.

  20. Fabrication and Characterization of Rapidly Oxidized p-Type Cu2O Films from Cu Films and their Application to Heterojunction Thin-Film Solar Cells

    Science.gov (United States)

    Kim, Hyung Soo; Lim, Jung Wook; Yun, Sun Jin; Park, Min A.; Park, Se Yong; Lee, Seong Eui; Lee, Hee Chul

    2013-10-01

    In this study, we report that the metal Cu deposited on a glass substrate is formed into a stable p-type Cu2O film with excellent properties through rapid thermal oxidation (RTO). The pre-deposited Cu film layer went through thermal oxidation in the temperature range of 200-500 °C in O2 and air ambient, and the electrical and optical properties were intensively investigated. The optimized p-type Cu2O film heat-treated at a temperature of 200 °C in an air ambient has a carrier concentration of 1.25×1017 cm-3, mobility of 0.51 cm2 V-1 s-1, and resistivity of 9.86 Ω cm; its optical band gap reaches about 2.4 eV. Using the p-type Cu2O film with i- and n-type amorphous silicon layers, heterojunction thin-film solar cells were fabricated on glass substrates. These transparent solar cells employed Ga-doped ZnO films as top and bottom electrodes. Solar cells with Cu2O film oxidized at 200 °C in an air ambient have an open circuit voltage of 0.36 V, short-circuit current of 15.2 mA/cm2, and photoelectric conversion efficiency of 1.98%.

  1. Optical and Recombination Losses in Thin Film Solar Cells Based on Heterojunctions n-ZnS (n-CdS) / p-CdTe with Current Collecting Contacts ITO and ZnO

    OpenAIRE

    O.A. Dobrozhan; A.S. Opanasyuk; V.V. Grynenko

    2014-01-01

    The optical and recombination losses in auxiliary and absorbing layers of solar cells based on heterojunctions n-ZnS / p-CdTe and n-CdS / p-CdTe with current collecting front sublayers ITO and ZnO were determined. As a result, spectral dependence of light transmittance (T) of solar cells, taking into account its reflections from the boundaries of the contacting materials and in case of absorption in the auxiliary layers of solar cells was calculated. The influence of optical and recombination...

  2. Organic tandem and multi-junction solar cells

    NARCIS (Netherlands)

    Hadipour, Afshin; de Boer, Bert; Blom, Paul W. M.

    2008-01-01

    The emerging field of stacked layers (double- and even multi-layers) in organic photovoltaic cells is reviewed. Owing to the limited absorption width of organic molecules and polymers, only a small fraction of the solar flux can be harvested by a single-layer bulk hetero-junction photovoltaic cell.

  3. A Bicontinuous Double Gyroid Hybrid Solar Cell : Letter

    NARCIS (Netherlands)

    Crossland, E.J.W.; Kamperman, M.M.G.; Nedelcu, M.; Ducati, C.; Wiesner, U.; Smilgies, D.M.; Toombes, G.E.S.; Hillmyer, M.A.; Ludwigs, S.; Steiner, U.; Snaith, H.J.

    2009-01-01

    We report the first successful application of an ordered bicontinuous gyroid semiconducting network in a hybrid bulk heterojunction solar cell. The freestanding gyroid network is fabricated by electrochemical deposition into the 10 nm wide voided channels of a self-assembled, selectively degradable

  4. Patterns of efficiency and degradation of composite polymer solar cells

    NARCIS (Netherlands)

    Jeranko, T; Tributsch, H; Sariciftci, NS; Hummelen, JC

    2004-01-01

    Bulk-heterojunction plastic solar cells (PSC) produced from a conjugated polymer, poly(2-methoxy-5-(3',7'-dimethyloctyl-oxy)-1,4-phenylenevinylene) (MDMO-PPV), and a methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) were investigated using photocurrent imaging techniques to determi

  5. Bipolar polaron pair recombination in polymer/fullerene solar cells

    DEFF Research Database (Denmark)

    Kupijai, Alexander J.; Behringer, Konstantin M.; Schaeble, Florian G.;

    2015-01-01

    We present a study of the rate-limiting spin-dependent charge-transfer processes in different polymer/fullerene bulk-heterojunction solar cells at 10 K. Observing central spin-locking signals in pulsed electrically detected magnetic resonance and an inversion of Rabi oscillations in multifrequency...

  6. Organic-inorganic heterojunction with P3HT and n-type 6H-SiC: Determination of the band alignment and photovoltaic properties

    Energy Technology Data Exchange (ETDEWEB)

    Dietmueller, Roland; Nesswetter, Helmut; Schoell, Sebastian; Hauer, Benedikt; Sharp, Ian David; Stutzmann, Martin [Walter Schottky Institut, Technische Universitaet Muenchen, Garching (Germany)

    2010-07-01

    The exact band alignment in organic/inorganic semiconductor heterojunctions is influenced by a variety of properties and difficult to predict. For the organic/inorganic heterojunction made of poly(3-hexylthiophene) (P3HT) and n-type 6H-SiC, the band alignment is determined via current-voltage measurements. For this purpose a model equivalent circuit, combining a thermionic emission diode and space-charge limited current effects, is proposed which describes the behavior of the heterojunction very well. From the fitting parameters, the interface barrier height of 1.1 eV between the lowest unoccupied molecular orbital (LUMO) of P3HT and the Fermi level of 6H-SiC can be determined. In addition from the maximum open circuit voltage of the diodes, a distance of 0.9 eV between the HOMO of P3HT and the conduction band (CB) of 6H-SiC can be deduced. These two values determine the Fermi level of 6H-SiC, which is about 120 meV below the CB, relative to the HOMO and LUMO of P3HT. The 6H-SiC/P3HT heterojunction exhibits an open circuit voltage of 0.55 eV at room temperature, which would make such a heterojunction a promising candidate for bulk heterojunction hybrid solar cells with 6H-SiC nanoparticles.

  7. Influences of bulk and surface recombinations on the power conversion efficiency of perovskite solar cells

    Science.gov (United States)

    Xie, Ziang; Sun, Shuren; Yan, Yu; Wang, Wei; Qin, Laixiang; Qin, G. G.

    2016-07-01

    For a novel kind of solar cell (SC) material, it is critical to estimate how far the power conversion efficiencies (PCEs) of the SCs made of it can go. In 2010 Han and Chen proposed the equation for the ultimate efficiency of SCs without considering the carrier recombination η un. η un is capable of estimating the theoretical upper limits of the SC efficiencies and has attracted much attention. However, carrier recombination, which is one of the key factors influencing the PCEs of the SCs, is ignored in the equation for η un. In this paper, we develop a novel equation to calculate the ultimate efficiency for the SCs, η ur, which considers both the bulk and the surface carrier recombinations. The novel equation for η ur can estimate how much the bulk and the surface carrier recombinations influence the PCEs of the SCs. Moreover, with η ur we can estimate how much PCE improvement space can be gained only by reducing the influence of the carrier recombination to the least. The perovskite organometal trihalide SCs have attracted tremendous attention lately. For the planar CH3NH3PbI3 SCs, in the material depth range from 31.25–2000 nm, we apply the equation of η ur to investigate how the bulk and the surface carrier recombinations affect PCE. From a typically reported PCE of 15% for the planar CH3NH3PbI3 SC, using the equation of η ur, it is concluded that by reducing the influence of carrier recombination to the least the improvement of PCE is in the range of 17–30%.

  8. Evolution of a Native Oxide Layer at the a-Si:H/c-Si Interface and Its Influence on a Silicon Heterojunction Solar Cell.

    Science.gov (United States)

    Liu, Wenzhu; Meng, Fanying; Zhang, Xiaoyu; Liu, Zhengxin

    2015-12-01

    The interface microstructure of a silicon heterojunction (SHJ) solar cell was investigated. We found an ultrathin native oxide layer (NOL) with a thickness of several angstroms was formed on the crystalline silicon (c-Si) surface in a very short time (∼30 s) after being etched by HF solution. Although the NOL had a loose structure with defects that are detrimental for surface passivation, it acted as a barrier to restrain the epitaxial growth of hydrogenated amorphous silicon (a-Si:H) during the plasma-enhanced chemical vapor deposition (PECVD). The microstructure change of the NOL during the PECVD deposition of a-Si:H layers with different conditions and under different H2 plasma treatments were systemically investigated in detail. When a brief H2 plasma was applied to treat the a-Si:H layer after the PECVD deposition, interstitial oxygen and small-size SiO2 precipitates were transformed to hydrogenated amorphous silicon suboxide alloy (a-SiO(x):H, x ∼ 1.5). In the meantime, the interface defect density was reduced by about 50%, and the parameters of the SHJ solar cell were improved due to the post H2 plasma treatment. PMID:26565116

  9. The roles of bulk and interfacial molecular orientations in determining the performance of organic bilayer solar cells

    KAUST Repository

    Ngongang Ndjawa, Guy O.

    2014-09-09

    Molecular orientation plays a significant role in determining the performance of small molecule solar cells. Key photovoltaic processes in these cells are strongly dependent on how the molecules are oriented in the active layer. We isolate contributions arising from the bulk molecular orientations vs. those from interfacial orientations in ZnPc/C60 bilayer systems and we probe these contributions by comparing device pairs in which only the bulk or the interface differ. By controlling the orientation in the bulk the current can be strongly modulated, whereas controlling the interfacial molecular orientation and degree of intermixing mediate the voltage.

  10. Solution-processed efficient CdTe nanocrystal/CBD-CdS hetero-junction solar cells with ZnO interlayer

    International Nuclear Information System (INIS)

    CdTe nanocrystal (NC)/CdS p–n hetero-junction solar cells with an ITO/ZnO-In/CdS/CdTe/MoOx/Ag-inverted structure were prepared by using a layer-by-layer solution process. The CdS thin films were prepared by chemical bath deposition on top of ITO/ZnO-In and were found to be very compact and pin-hole free in a large area, which insured high quality CdTe NCs thin-film formation upon it. The device performance was strongly related to the CdCl2 annealing temperature and annealing time. Devices exhibited power conversion efficiency (PCE) of 3.08 % following 400 °C CdCl2 annealing for 5 min, which was a good efficiency for solution processed CdTe/CdS NC-inverted solar cells. By carefully designing and optimizing the CdCl2-annealing conditions (370 °C CdCl2 annealing for about 15 min), the PCE of such devices showed a 21 % increase, in comparison to 400 °C CdCl2-annealing conditions, and reached a better PCE of 3.73 % while keeping a relatively high VOC of 0.49 V. This PCE value, to the best of our knowledge, is the highest PCE reported for solution processed CdTe–CdS NC solar cells. Moreover, the inverted solar cell device was very stable when kept under ambient conditions, less than 4 % degradation was observed in PCE after 40 days storage

  11. Heterojunction solar cell with 6% efficiency based on an n-type aluminum-gallium-oxide thin film and p-type sodium-doped Cu2O sheet

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2015-02-01

    In this paper, we describe efforts to enhance the efficiency of Cu2O-based heterojunction solar cells fabricated with an aluminum-gallium-oxide (Al-Ga-O) thin film as the n-type layer and a p-type sodium (Na)-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing copper sheets. The optimal Al content [X; Al/(Ga + Al) atomic ratio] of an AlX-Ga1-X-O thin-film n-type layer was found to be approximately 2.5 at. %. The optimized resistivity was approximately 15 Ω cm for n-type AlX-Ga1-X-O/p-type Cu2O:Na heterojunction solar cells. A MgF2/AZO/Al0.025-Ga0.975-O/Cu2O:Na heterojunction solar cell with 6.1% efficiency was fabricated using a 60-nm-thick n-type oxide thin-film layer and a 0.2-mm-thick Cu2O:Na sheet with the optimized resistivity.

  12. Efficiency enhancement using a Zn1‑ x Ge x -O thin film as an n-type window layer in Cu2O-based heterojunction solar cells

    Science.gov (United States)

    Minami, Tadatsugu; Nishi, Yuki; Miyata, Toshihiro

    2016-05-01

    Efficiency enhancement was achieved in Cu2O-based heterojunction solar cells fabricated with a zinc–germanium-oxide (Zn1‑ x Ge x -O) thin film as the n-type window layer and a p-type Na-doped Cu2O (Cu2O:Na) sheet prepared by thermally oxidizing Cu sheets. The Ge content (x) dependence of the obtained photovoltaic properties of the heterojunction solar cells is mainly explained by the conduction band discontinuity that results from the electron affinity difference between Zn1‑ x Ge x -O and Cu2O:Na. The optimal value of x in Zn1‑ x Ge x -O thin films prepared by pulsed laser deposition was observed to be 0.62. An efficiency of 8.1% was obtained in a MgF2/Al-doped ZnO/Zn0.38Ge0.62-O/Cu2O:Na heterojunction solar cell.

  13. Band alignment at organic-inorganic heterojunctions between P3HT and n-type 6H-SiC.

    Science.gov (United States)

    Dietmueller, Roland; Nesswetter, Helmut; Schoell, Sebastian J; Sharp, Ian D; Stutzmann, Martin

    2011-11-01

    The exact band alignment at organic/inorganic semiconductor heterojunctions is influenced by a variety of properties and is difficult to predict. For organic/inorganic bilayer heterojunctions made of poly(3-hexylthiophene) (P3HT) and n-type 6H-SiC, the band alignment is determined via current-voltage measurements. For this purpose, a model equivalent circuit, combining thermionic emission and space-charge-limited current effects, is proposed which describes the behavior of the heterojunction very well. From the fitting parameters, an interface barrier height of 1.1 eV between the lowest unoccupied molecular orbital (LUMO) of P3HT and the conduction band (CB) of 6H-SiC is determined. In addition, from the maximum open circuit voltage of 6H-SiC/P3HT diodes, a difference of 0.9 eV between the highest occupied molecular orbital (HOMO) of P3HT and the CB of 6H-SiC is deduced. These two values determine the alignment of the energy bands of 6H-SiC relative to the HOMO and LUMO of P3HT. The 6H-SiC/P3HT bilayer heterojunction exhibits an open circuit voltage of ~0.5 V at room temperature, which makes such a materials system a potential candidate for bulk heterojunction hybrid solar cells with 6H-SiC nanoparticles. PMID:21936559

  14. Electrospinning Nanofiber Based Organic Solar Cell

    Science.gov (United States)

    Yang, Zhenhua; Liu, Ying; Moffa, Maria; Nam, Chang-Yong; Pisignano, Dario; Rafailovich, Miriam

    Bulk heterojunction (BHJ) polymer solar cells are an area of intense interest due to their potential to result in printable, inexpensive solar cells which can be processed onto flexible substrates. The active layer is typically spin coated from the solution of polythiophene derivatives (donor) and fullerenes (acceptor) and interconnected domains are formed because of phase separation. However, the power conversion efficiency (PCE) of BHJ solar cell is restricted by the presence of unfavorable morphological features, including dead ends or isolated domains. Here we MEH-PPV:PVP:PCBM electrospun nanofiber into BHJ solar cell for the active layer morphology optimization. Larger interfacial area between donor and acceptor is abtained with electrospinning method and the high aspect ratio of the MEH-PPV:PVP:PCBM nanofibers allow them to easily form a continuous pathway. The surface morphology is investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrospun nanofibers are discussed as a favorable structure for application in bulk-heterojunction organic solar cells. Electrospinning Nanofiber Based Bulk Heterojunction Organic Solar Cell.

  15. Dependence of Photovoltaic Property of ZnO/Si Heterojunction Solar Cell on Thickness of ZnO Films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-Ying; ZHONG Sheng; SUN Li-Jie; FU Zhu-Xi

    2008-01-01

    N-ZnO/p-Si heterojunctions are prepared by sputtering deposition of intrinsic ZnO films on p-Si substrates.Thicknesses of ZnO films are altered by varying the deposition time from I h to 3 h.The electrical properties of these structures are analysed from capacitance-voltage ( C- V) and current-voltage (I- V) characteristics performed in a dark room.The results demonstrated that all the samples show strong rectifying behaviour.Photovoltalc property for the samples with different thicknesses of ZnO films are investigated by measuring open circuit voltage and short circuit current.It is found that photovoltages are kept to be almost constant of 32OmV along with the thickness while photocurrents changing a lot.The variation mechanism of the photovoltalc effect as a function of thickness of ZnO films is investigated.

  16. Demonstration of solar-blind Al{sub x}Ga{sub 1−x}N-based heterojunction phototransistors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingxia; Tang, Shaoji; Liu, Changshan; Li, Bin; Wu, Hualong; Wang, Hailong [School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wu, Zhisheng [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); Jiang, Hao, E-mail: stsjiang@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); School of Microelectronics, Sun Yat-sen University, Guangzhou 510275 (China)

    2015-12-07

    Al{sub 0.4}Ga{sub 0.6}N/Al{sub 0.65}Ga{sub 0.35}N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 10{sup 3} was obtained at 6 V bias.

  17. Increasing optical density of single-layer multi-polymer bulk-heterojunction OPVs using CdSe(ZnS) core(shell) quantum dots

    Science.gov (United States)

    Bump, Buddy J.; Olson, Grant T.; Savage, Richard; Echols, Robert S.

    2014-10-01

    Photovoltaic technology has powerful implications from commercial and national security standpoints. Due to the high material cost of silicon solar devices, inexpensive and lightweight polymer based solar is desirable to meet the demand for decentralized electrical power production in traditionally "off-grid" areas. Using a blend of Poly(3-hexylthiophene- 2,5-diyl) (P3HT), Phenyl-C61-butyric acid methyl ester (PCBM), and the low band-gap polymer Poly[2,6-(4,4-bis-(2- ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT), we have fabricated devices with a wide spectral response and 3% power conversion efficiency in AM 1.5 conditions. Due to low absorptivity in the peak of the solar spectra (500nm), we have blended this previous polymer system with CdSe(ZnS) core (shell) quantum dots to improve absorption, and thus power conversion efficiencies. Devices were prepared with quantum dots having a peak absorbance at 560nm and an emission wavelength of 577nm, with device loading ranging from 0% to 2.7% by weight. The relationship between quantum dot concentration and device performance is discussed, along with the impact of quantum dot concentration on thermal resistance to morphology changes.

  18. Crystalline Fraction and Doping Concentration Effect on Heterojunction Solar Cells n-Doped µc-Si:H Back Surface Field Layer.

    Science.gov (United States)

    Kim, Sangho; Shin, Chonghoon; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    The back surface field (BSF) plays a vital role for high efficiency in the Heterojunction Intrinsic Thin (HIT) film solar cell. This paper investigated the effect of crystalline volume fraction (Xc) and 1% hydrogen diluted phosphine (PH3) gas doping concentration of the n-type µc-Si:H back surface file (BSF) layer. Initially, the thickness of the n-type µc-Si:H BSF layer was optimized. With increase in Xc from 6% to 59%, the open circuit voltage (Voc) increased from 573 mV to 696 mV, and the fill factor (FF) also increased from 59% to 71%. In the long wavelengths region (≥ 950 nm), the QE of the solar cells decreased over the optimized Xc of the n-doped micro BSF layer, due to the defects of a film. In the second part of this paper, the effect of high conductivity n-type µc-Si:H BSF layer with optimized thickness on the performance of HIT solar cells was investigated, by doping gas ratio variation. Even though Xc decreased, conductivity was increased, with increasing PH3 doping concentration. Under the optimized condition, a n-µc-Si:H BSF layer has a dark conductivity of 2.59 S/cm, activation energy of 0.0519 eV, and X, of 52%. The conversion efficiency of 18.9% was achieved with a Voc of 706 mV, fill factor of 72%, and short circuit current density of 37.1 mW·cm(-2).

  19. Largely enhanced efficiency with a PFN/Al bilayer cathode in high efficiency bulk heterojunction photovoltaic cells with a low bandgap polycarbazole donor

    Energy Technology Data Exchange (ETDEWEB)

    He, Zhicai; Zhang, Chen; Xu, Xiaofeng; Zhang, Lianjie; Huang, Liang; Chen, Junwu; Wu, Hongbin; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Physics and Chemistry of Luminescence, South China University of Technology, Guangzhou 510640 (China)

    2011-07-19

    Quinoxaline-containing poly(4,5-ethylene-2,7-carbazole) (PECz-DTQx) shows a high efficiency of 6.07% in solar cells with a PFN/Al bilayer cathode. This is higher than the efficiency achieved with sole Al (3.99%) or with Ca/Al (4.52%) cathodes. A bilayer cathode could be valuable in device configurations to achieve high efficiency in combination with a high-performance polymer donor. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Photovoltaic properties of ZnO/CdTe heterojunctions prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    An extended investigation has been made of the electrical and photovoltaic properties of heterojunctions prepared by spray-pyrolysis deposition of thin ZnO films on single-crystal p-type CdTe. The principal experimental variables were the substrate temperature and the postdeposition temperature for annealing in H2. Under actual sunlight the optimum cell showed an open-circuit voltage of 0.54 V, a short-circuit current of 19.5 mA/cm2, and a solar efficiency (referred to the active area) of 8.8%, the highest value obtained to date for an authentic heterojunction on CdTe. The nature of the forward transport mechanism has been investigated, and a tunneling model in which bulk and interface deep traps control the forward characteristics is shown to provide good correlation with the experimental data

  1. Evaluation of the indium gallium nitride/silicon broken-gap heterojunction and its potential application for solar cells

    Science.gov (United States)

    Yao, Yuan

    InGaN (especially In-rich alloy) has been actively studied for decades since the band gap of InN was revised downward from ˜2.0 eV to 0.64 eV. The potential applications for alloys of In-rich InGaN hence became apparent. Despite the promising potential, photovoltaic devices based on InGaN have struggled due to a number of key limitations and fundamental physical problems. Firstly, due to the deep excursion of the InN conduction band at the gamma point, defects in InN are almost universally n-type leading to unintentional degenerate doping. This also leads to the problem of electron accumulation at all surfaces and interfaces of InN. Secondly, p-type doping is problematic, partially due to the degenerate doping effect of defects, but it has also been observed that Mg-doping, while leading to a p-type layer, dramatically reduces the quantum efficiency. This thesis explores an alternative approach using n-type InGaN to form a heterojunction with a p-type Si substrate. One potential benefit to using p-type Si as a substrate material for InGaN is that the valence band of Si possibly lines up with the conduction band of InGaN for a specific mole fraction of indium. Such a band alignment is known as a broken gap heterojunction, an example of which is the interface between InAs and AlxGa 1--xSb. The benefits of this broken-gap junction include a low series resistance, high electron mobility, and mobility only weakly dependent on temperature. These properties enable new approach to photovoltaic devices. The InGaN/Si heterojunctions were fabricated by plasma-assisted molecular beam epitaxy under stoichiometric flux conditions. An ultra-thin SiN interface layer was introduced, by Si nitridation process, to passivate the substrate surface and prevent In-Si and Ga-Si eutectic problems. InGaN films with a variety of indium mole fractions were grown by calibrating the In/Ga flux ratio during the deposition. The chemical composition of as-grown films was characterized by x

  2. Behavior of Photocarriers in the Light-Induced Metastable State in the p-n Heterojunction of a Cu(In,Ga)Se2 Solar Cell with CBD-ZnS Buffer Layer.

    Science.gov (United States)

    Lee, Woo-Jung; Yu, Hye-Jung; Wi, Jae-Hyung; Cho, Dae-Hyung; Han, Won Seok; Yoo, Jisu; Yi, Yeonjin; Song, Jung-Hoon; Chung, Yong-Duck

    2016-08-31

    We fabricated Cu(In,Ga)Se2 (CIGS) solar cells with a chemical bath deposition (CBD)-ZnS buffer layer grown with varying ammonia concentrations in aqueous solution. The solar cell performance was degraded with increasing ammonia concentration, due to actively dissolved Zn atoms during CBD-ZnS precipitation. These formed interfacial defect states, such as hydroxide species in the CBD-ZnS film, and interstitial and antisite Zn defects at the p-n heterojunction. After light/UV soaking, the CIGS solar cell performance drastically improved, with a rise in fill factor. With the Zn-based buffer layer, the light soaking treatment containing blue photons induced a metastable state and enhanced the CIGS solar cell performance. To interpret this effect, we suggest a band structure model of the p-n heterojunction to explain the flow of photocarriers under white light at the initial state, and then after light/UV soaking. The determining factor is a p+ defect layer, containing an amount of deep acceptor traps, located near the CIGS surface. The p+ defect layer easily captures photoexcited electrons, and then when it becomes quasi-neutral, attracts photoexcited holes. This alters the barrier height and controls the photocurrent at the p-n junction, and fill factor values, determining the solar cell performance.

  3. Coarsening of one-step deposited organolead triiodide perovskite films via Ostwald ripening for high efficiency planar-heterojunction solar cells.

    Science.gov (United States)

    Zhu, Weidong; Bao, Chunxiong; Wang, Yangrunqian; Li, Faming; Zhou, Xiaoxin; Yang, Jie; Lv, Bihu; Wang, Xiaoyong; Yu, Tao; Zou, Zhigang

    2016-05-01

    Large organolead triiodide perovskite (OTP) grains with little intragranular defects are beneficial to minimize carrier recombination, hence boosting cell performance. However, OTP films deposited by the widely used one-step spin-coating route are usually composed of small grains, because the poor thermal stability of OTP inherently restricts the processing window (temperature, time) during the film preparation, thus limiting grain coarsening in the film. Herein, the remarkable grain coarsening via Ostwald ripening in one-step deposited OTP films has been successfully realized by a facile and effective post-synthesis high-temperature heating treatment assisted with spin-coated CH3NH3I. By systematically investigating the heating treatment parameters, a high-quality OTP film with an enlarged average grain size from ∼280 nm to 1.2 μm, greatly enhanced crystallinity, and excellent stoichiometry is achieved. Benefiting from such improved features, this modified film shows significantly reduced defect states corresponding to the decrease of recombination centers, as well as enhanced carrier transport and injection properties, which lead to the dramatically boosted efficiency from 14.54% to 16.88% for planar-heterojunction solar cells. More importantly, the improved OTP film quality provides the possibility of thickening the absorber layer of cells to realize more sufficient absorption without serious aggravation of charge recombination. By further optimizing the thickness of the coarsened OTP films, highly efficient cells with relatively excellent reproducibility and an optimal efficiency of 19.24% are achieved. PMID:27064445

  4. Potential application of mono/bi-layer molybdenum disulfide (MoS2) sheet as an efficient transparent conducting electrode in silicon heterojunction solar cells

    Science.gov (United States)

    Chaudhary, Rimjhim; Patel, Kamlesh; Sinha, Ravindra K.; Kumar, Sanjeev; Tyagi, Pawan K.

    2016-07-01

    In this paper, we have simulated the structure of n-type MoS2/silicon heterojunction solar cell and studied its function under different conditions. The optimization of parameters of the cell's layer has been carried out by using AFORS-HET software. In the present study, MoS2 has been considered as 3-D in nature instead of the reported 2-D nature. In order to ensure the formation of Schottky junction, electric contact has been made along the c-axis to collect the minority charge carriers. After optimizing the various parameters of n-type single layer MoS2, power efficiency of 12.44% has been achieved at the room temperature, which has further decreased to 9.042% as the layer number has increased up to 40. Furthermore, after optimizing the parameters of silicon wafer maximum efficiency of 16.4% has been achieved. Temperature dependence of the cell performance has also been studied and the maximum efficiency has been achieved at 300 K. In the present study, we have demonstrated that n-type ultrathin layer of MoS2 can be used as an excellent transparent conducting electrode.

  5. Coarsening of one-step deposited organolead triiodide perovskite films via Ostwald ripening for high efficiency planar-heterojunction solar cells.

    Science.gov (United States)

    Zhu, Weidong; Bao, Chunxiong; Wang, Yangrunqian; Li, Faming; Zhou, Xiaoxin; Yang, Jie; Lv, Bihu; Wang, Xiaoyong; Yu, Tao; Zou, Zhigang

    2016-05-01

    Large organolead triiodide perovskite (OTP) grains with little intragranular defects are beneficial to minimize carrier recombination, hence boosting cell performance. However, OTP films deposited by the widely used one-step spin-coating route are usually composed of small grains, because the poor thermal stability of OTP inherently restricts the processing window (temperature, time) during the film preparation, thus limiting grain coarsening in the film. Herein, the remarkable grain coarsening via Ostwald ripening in one-step deposited OTP films has been successfully realized by a facile and effective post-synthesis high-temperature heating treatment assisted with spin-coated CH3NH3I. By systematically investigating the heating treatment parameters, a high-quality OTP film with an enlarged average grain size from ∼280 nm to 1.2 μm, greatly enhanced crystallinity, and excellent stoichiometry is achieved. Benefiting from such improved features, this modified film shows significantly reduced defect states corresponding to the decrease of recombination centers, as well as enhanced carrier transport and injection properties, which lead to the dramatically boosted efficiency from 14.54% to 16.88% for planar-heterojunction solar cells. More importantly, the improved OTP film quality provides the possibility of thickening the absorber layer of cells to realize more sufficient absorption without serious aggravation of charge recombination. By further optimizing the thickness of the coarsened OTP films, highly efficient cells with relatively excellent reproducibility and an optimal efficiency of 19.24% are achieved.

  6. Progress in polymer solar cell

    Institute of Scientific and Technical Information of China (English)

    LI LiGui; LU GuangHao; YANG XiaoNiu; ZHOU EnLe

    2007-01-01

    This review outlines current progresses in polymer solar cell. Compared to traditional silicon-based photovoltaic (PV) technology, the completely different principle of optoelectric response in the polymer cell results in a novel configuration of the device and more complicated photovoltaic generation process. The conception of bulk-heterojunction (BHJ) is introduced and its advantage in terms of morphology is addressed. The main aspects including the morphology of photoactive layer, which limit the efficiency and stability of polymer solar cell, are discussed in detail. The solutions to boosting up both the efficiency and stability (lifetime) of the polymer solar cell are highlighted at the end of this review.

  7. Correlation between dynamic parameters and device performance of organic solar cells

    OpenAIRE

    Kniepert, Juliane

    2015-01-01

    Organic bulk heterojunction (BHJ) solar cells based on polymer:fullerene blends are a promising alternative for a low-cost solar energy conversion. Despite significant improvements of the power conversion efficiency in recent years, the fundamental working principles of these devices are yet not fully understood. In general, the current output of organic solar cells is determined by the generation of free charge carriers upon light absorption and their transport to the electrodes in competiti...

  8. Realization of 13.6% Efficiency on 20 μm Thick Si/Organic Hybrid Heterojunction Solar Cells via Advanced Nanotexturing and Surface Recombination Suppression.

    Science.gov (United States)

    He, Jian; Gao, Pingqi; Liao, Mingdun; Yang, Xi; Ying, Zhiqin; Zhou, Suqiong; Ye, Jichun; Cui, Yi

    2015-06-23

    Hybrid silicon/polymer solar cells promise to be an economically feasible alternative energy solution for various applications if ultrathin flexible crystalline silicon (c-Si) substrates are used. However, utilization of ultrathin c-Si encounters problems in light harvesting and electronic losses at surfaces, which severely degrade the performance of solar cells. Here, we developed a metal-assisted chemical etching method to deliver front-side surface texturing of hierarchically bowl-like nanopores on 20 μm c-Si, enabling an omnidirectional light harvesting over the entire solar spectrum as well as an enlarged contact area with the polymer. In addition, a back surface field was introduced on the back side of the thin c-Si to minimize the series resistance losses as well as to suppress the surface recombination by the built high-low junction. Through these improvements, a power conversion efficiency (PCE) up to 13.6% was achieved under an air mass 1.5 G irradiation for silicon/organic hybrid solar cells with the c-Si thickness of only about 20 μm. This PCE is as high as the record currently reported in hybrid solar cells constructed from bulk c-Si, suggesting a design rule for efficient silicon/organic solar cells with thinner absorbers.

  9. Addition of P3HT-grafted Silica nanoparticles improves bulk-heterojunction morphology in P3HT-PCBM blends

    Science.gov (United States)

    Garg, Mohit; Padmanabhan, Venkat

    2016-09-01

    We present molecular dynamics simulations of a ternary blend of P3HT, PCBM and P3HT-grafted silica nanoparticles (SiNP) for applications in polymer-based solar cells. Using coarse-grained models, we study the effect of SiNP on the spatial arrangement of PCBM in P3HT. Our results suggest that addition of SiNP not only alters the morphology of PCBM clusters but also improves the crystallinity of P3HT. We exploit the property of grafted SiNP to self-assemble into a variety of anisotropic structures and the tendency of PCBM to preferentially adhere to SiNP surface, due to favorable interactions, to achieve morphologies with desirable characteristics for the active layer, including domain size, crystallinity of P3HT, and elimination of isolated islands of PCBM. As the concentration of SiNP increases, the number of isolated PCBM molecules decreases, which in turn improves the crystallinity of P3HT domains. We also observe that by tuning the grafting parameters of SiNP, it is possible to achieve structures ranging from cylindrical to sheets to highly interconnected network of strings. The changes brought about by addition of SiNP shows a promising potential to improve the performance of these materials when used as active layers in organic photovoltaics.

  10. Addition of P3HT-grafted Silica nanoparticles improves bulk-heterojunction morphology in P3HT-PCBM blends.

    Science.gov (United States)

    Garg, Mohit; Padmanabhan, Venkat

    2016-01-01

    We present molecular dynamics simulations of a ternary blend of P3HT, PCBM and P3HT-grafted silica nanoparticles (SiNP) for applications in polymer-based solar cells. Using coarse-grained models, we study the effect of SiNP on the spatial arrangement of PCBM in P3HT. Our results suggest that addition of SiNP not only alters the morphology of PCBM clusters but also improves the crystallinity of P3HT. We exploit the property of grafted SiNP to self-assemble into a variety of anisotropic structures and the tendency of PCBM to preferentially adhere to SiNP surface, due to favorable interactions, to achieve morphologies with desirable characteristics for the active layer, including domain size, crystallinity of P3HT, and elimination of isolated islands of PCBM. As the concentration of SiNP increases, the number of isolated PCBM molecules decreases, which in turn improves the crystallinity of P3HT domains. We also observe that by tuning the grafting parameters of SiNP, it is possible to achieve structures ranging from cylindrical to sheets to highly interconnected network of strings. The changes brought about by addition of SiNP shows a promising potential to improve the performance of these materials when used as active layers in organic photovoltaics. PMID:27628895

  11. Interlayer adhesion in roll-to-roll processed flexible inverted polymer solar cells

    DEFF Research Database (Denmark)

    Dupont, Stephanie R.; Oliver, Mark; Krebs, Frederik C;

    2012-01-01

    The interlayer adhesion of roll-to-roll processed flexible inverted P3HT:PCBM bulk heterojunction (BHJ) polymer solar cells is reported. Poor adhesion between adjacent layers may result in loss of device performance from delamination driven by the thermomechanical stresses in the device. We...

  12. Hybrid polymer solar cells from highly reactive diethylzinc : MDMO-PPV versus P3HT

    NARCIS (Netherlands)

    Moet, Date J.D.; Koster, L. Jan Anton; Boer, Bert de; Blom, Paul W.M.

    2007-01-01

    The degradation of poly[2-methoxy-5-(3',7'-dimethyloetyloxy)-p-phenylene vinylene] (MDMO-PPV) during the processing of hybrid organic/inorganic bulk-heterojunction solar cells with zinc oxide (ZnO) from a molecular precursor as acceptor is reported. Upon addition of diethylzinc, the absorption spect

  13. Structure-Property Relations in Polymer:Fullerene Blends for Organic Solar Cells.

    Science.gov (United States)

    Banerji, Natalie

    2016-01-01

    Organic solar cells consist of thin films combining an electron donor (often a conjugated polymer) with an electron acceptor (often a fullerene derivative), in a blend commonly referred to as bulk heterojunction material. Charge separation between the donor and the acceptor leads to the generation of carriers, which can be extracted from photovoltaic devices in the form of photocurrent. The generation mechanism of free, extractable charges has caused a lot of controversial discussion in literature. Our research has shown that all the steps involved in charge generation are strongly dependent on the arrangement of the donor and the acceptor (i.e. the structure) of the bulk heterojunction. PMID:27561613

  14. Enhancement of Efficiency of a Solar Cell Fabricated on Black Si Made by Inductively Coupled Plasma-Reactive Ion Etching Process: A Case Study of a n-CdS/p-Si Heterojunction Cell.

    Science.gov (United States)

    Katiyar, Ajit K; Mukherjee, S; Zeeshan, M; Ray, Samit K; Raychaudhuri, A K

    2015-10-28

    We show that a significant enhancement of solar cell efficiency can be achieved in cells fabricated on black Si made using inductively coupled plasma-reactive ion etching (ICP-RIE). The ICP-RIE-fabricated black Si results in an array of vertically oriented defect-free Si nanocones (average height ∼150 nm; apex diameter ∼25 nm) exhibiting an average reflectance ≤2% over most of the relevant solar spectral range. The enabling role of the ultralow reflectance of the nanostructured black Si has been demonstrated using a heterojunction solar cell fabricated by depositing a n-type CdS film on p-Si nanocones followed by a transparent conducting coating of Al-doped ZnO (AZO). The fabricated n-CdS/p-Si heterojunction exhibits promising power conversion efficiency close to 3%, up from a mere efficient 0.15% for a similar cell fabricated on a planar Si. The effect of the fabrication process for the black Si on solar cell performance has been investigated through the measurements of carrier lifetime and surface recombination velocity. The accompanying model and simulation analysis shows that the conical structure leads to the effective dielectric constant varying smoothly from the value of the air at the top to the value of Si at the base over the length of the nanocone, leading to a substantial reduction of its reflectance.

  15. 两种异质结太阳能电池聚合物供体材料的设计与理论性质%Theory Design of Two Polymer Donors for Organic Heterojunction Solar Cells

    Institute of Scientific and Technical Information of China (English)

    刘小锐; 陈春香; 何荣幸; 申伟; 李明

    2012-01-01

    organic solar cell.Therefore,we can infer that PBnDT-6CNTAZ may be a potential donor material of bulk heterojunction solar cells.The present calculated results demonstrated a first attempt of providing a theoretical model for the introduction of electron-deficient groups in copolymer donors.These results may provide a structural guideline for optimizing chemical construction of copolymer donors to improve the performance of bulk heterojunction solar cells.Our computational models and conclusions can be applied to design and predict other new polymer donors.%模拟了以苯并噻吩作为富电子基团分别与1H-benzo[d][1,2,3]triazole和1H-benzo[d][1,2,3]triazole-6-carbonitrile作为缺电子基团构成的两种聚合物太阳能电池供体材料(PBnDT-HTAZ,PBnDT-6CNTAZ)及PC60BM为受体材料的理论性质.利用DFT理论分析了两种聚合物的电子和光物理性质,通过Marcus理论研究了供-受体化合物在供受体界面的电荷转移性质和供体聚合物的空穴迁移能力.计算结果表明:供体聚合物具有强而宽的吸收,并且具有强的分子内电子转移和从电子供体到电子受体的分子间电子转移,对应的复合物都具有较小的激子束缚能;与PBnDT-HTAZ相比,设计的供体PBnDT-6CNTAZ,由于引入了强吸电性的氰基而具有更大的开路电压和更好的抗氧化能力,另外,在供受体界面具有更好的电荷转移特性,并且在供体中具有相对大的空穴迁移速率.因此,可以推断得知引入氰基的PBnDT-6CNTAZ是一种潜在的更好的太阳能电池供体材料.

  16. 细致平衡理论计算CdS/CdTe异质结太阳电池的极限转换效率%DETAIL BALANCE LIMIT OF EFFICIENCY OF CdS/CdTe HETEROJUNCTION SOLAR CELLS

    Institute of Scientific and Technical Information of China (English)

    熊超; 陈磊; 袁洪春; 姚若河

    2013-01-01

    Based on detailed balance theory and considered the barriers at interface of heterojunction,which result from the band offset and block photon-generated carriers transport,a photoelectric conversion model for heterojunction solar cells was established.The problem of the limit efficiency of heterojunction solar cells was solved using the detailed balance theory.A method to realize the Ⅰ-Ⅴ characteristics of the CdS/CdTe heterojunction solar cells under the illumination and the limit conversion efficiency of CdS/CdTe solar cells was proposed in this article.Under the illumination,the Ⅰ-Ⅴ characteristics and maximum conversion efficiency are closely related to the built-in barrier of the CdS/CdTe solar cells.It is shown that a theoretical efficiency limit of 29% can be achieved for CdS/CdTe heterojunction solar cells under AM1.5 illumination.Considering the typical parameters of CdS and CdTe,the maximum conversion efficiency of 25% can be achieved.Analysis of the reality of the efficiency is not high and the feasibility of improving conversion efficiency of the CdS/CdTe heterojunction solar cells.%在细致平衡理论基础上,针对异质结电池在结处由于能带不连续而形成载流子运动势垒可能对光生载流子的运输存在阻碍作用,建立异质结太阳电池的光电转换模型,解决了细致平衡理论无法计算异质结太阳电池极限效率的问题,推导出CdS/CdTe异质结太阳电池光照下的Ⅰ-Ⅴ特性表达式以及最大光电转换效率的求法.指出电池的Ⅰ-Ⅴ特性以及最大转换效率与电池的内建势垒密切相关,并求出在理想情况AM1.5的光照下CdS/CdTe异质结太阳电池最大转换效率可达29%;考虑到CdS和CdTe的典型参数后,计算出其最大转换效率可达25%.分析了现实中电池效率不高的原因,并指出实现电池转换效率提高的可行性.

  17. Structural, electronic and transport properties of armorphous/crystalline silicon heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Tim Ferdinand

    2011-06-15

    application of established concepts for the physical description of a-Si:H in the following chapters. Further, the impact of the PECVD deposition parameters on the properties of the resulting layers is explored and discussed. Next, the lineup of the electronic bands at the heterojunction is elucidated in devicerelevant a-Si:H/c-Si heterostructures. To this end, a novel method combining photoelectron spectroscopy and surface photovoltage measurements is developed and employed. It is found that upon widening the a-Si:H optical band gap by controlling its hydrogen content, predominantly the valence band offset is increasing while the conduction band offset stays constant. The significance of the valence band offset for solar cell operation and possible pathways for tailoring the electronic properties of the heterojunction are discussed. In the last chapter, the microscopic properties of the a- Si:H layers are linked with the resulting passivation of c-Si surface states, which limit the obtainable open-circuit-voltage in a heterojunction solar cell. It is found that in case of ideal processing, the heterojunction does not possess particular properties but can be described by the a-Si:H bulk properties projected onto the actual heterojunction. The principal limit of c-Si surface passivation follows naturally, as does the explanation of passivation degradation effects from the metastability inherent to a-Si:H. The amorphous network has the propensity to adapt upon changes in externally controllable parameters like the Fermi energy. (orig.)

  18. Effects of bath composition on the morphology of electroless-plated Cu electrodes for hetero-junctions with intrinsic thin layer solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woon Young [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Lee, Yu Jin [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Department of Materials Science & Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Lee, Min Hyung, E-mail: minhyung@kitech.re.kr [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of)

    2015-07-31

    The morphology of an electroless-plated Cu electrode was investigated as a function of bath composition. To enhance the selectivity of Cu electrode deposition on the surface of an indium tin oxide layer, a Ti/Cu multi-layer was deposited as a Cu electrode seed layer by physical vapor deposition, and then electroless plating was performed using various complexing agents and a surfactant. The degree of selectivity was effectively influenced by the type of complexing agent. The electroless plating solution containing N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) as complexing agent showed excellent selective growth of the Cu electrode as compared to the solution containing ethylenediaminetetraacetic acid. Even though THPED led to better selective growth of the electroless-plated Cu electrode, the aspect ratio of electrode lateral growth was about 2.7 times that of vertical growth. By adding a nonionic surfactant, the ratio between vertical growth rate and lateral growth rate was improved about 4.6 times. The Cu–THPED electroless plating with nonionic surfactant provided a drastic decrease in lateral growth rate, compared with the Cu–THPED electroless plating bath excluding nonionic surfactant. The Cu–THPED solution including nonionic surfactant is a promising composition of electroless plating solution for the clear selective plating of Cu electrodes on hetero-junctions with intrinsic thin layer solar cells. - Highlights: • Selective electroless plating (SEP) depends on binding strength of complexing agent. • The SEP was performed using Cu-N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine. • A surfactant is able to remove hydrogen bubbles on Cu electrode surface. • The growth of Cu electrode was improved in vertical direction by adding surfactant.

  19. Thermodynamic efficiency limit of molecular donor-acceptor solar cells and its application to diindenoperylene/C{sub 60}-based planar heterojunction devices

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Mark; Wagner, Julia; Hoermann, Ulrich; Opitz, Andreas; Bruetting, Wolfgang [Institut fuer Physik, Universitaet Augsburg, Universitaetsstr.1, 86135 Augsburg (Germany); Klein, Konrad; Stutzmann, Martin [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany)

    2012-09-15

    In organic photovoltaic (PV) cells, the well-established donor-acceptor (D/A) concept enabling photo-induced charge transfer between two partners with suitable energy level alignment has proven extremely successful. Nevertheless, the introduction of such a heterojunction is accompanied with additional energy losses as compared to an inorganic homojunction cell, owing to the presence of a charge-transfer (CT) state at the D/A interface. Based on the principle of detailed balance, a modified Shockley-Queisser theory is developed including the essential effects of interfacial CT states, that allows for a quantitative assessment of the thermodynamic efficiency limits of molecular D/A solar cells. Key parameters, apart from the optical gap of the absorber material, entering the model are the energy (E{sub CT}) and relative absorption strength ({alpha}{sub CT}) of the CT state. It is demonstrated how the open-circuit voltage (V{sub OC}) and thus the power conversion efficiency are affected by different parameter values. Furthermore, it is shown that temperature dependent device characteristics can serve to determine the CT energy, and thus the upper limit of V{sub OC} for a given D/A combination, as well as to quantify non-radiative recombination losses. The model is applied to diindenoperylene (DIP)-based photovoltaic devices, with open-circuit voltages between 0.9 and 1.4 V, depending on the partner, that have recently been reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Thermally reactive Thiazolo[5,4-d]thiazole based copolymers for high photochemical stability in polymer solar cells

    DEFF Research Database (Denmark)

    Helgesen, Martin; Vesterager Madsen, Morten; Andreasen, Birgitta;

    2011-01-01

    New thermally reactive copolymers based on dithienylthiazolo[5,4-d]thiazole (DTZ) and silolodithiophene (SDT) have been synthesized and explored in bulk heterojunction solar cells as mixtures with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). In thin films the polymers had optical band gaps in...

  1. Investigation of optical spacer layers from solution based precursors for polymer solar cells using X-ray reflectometry

    DEFF Research Database (Denmark)

    Andersen, Philip Hvidthøft Delff; Skårhøj, Jakob; Andreasen, Jens Wenzel;

    2009-01-01

    Optical spacer layers based on titaniumalkoxide precursor solutions were prepared by spin-coating on top of bulk heterojunction layers based on poly-3-hexylthiophene (P3HT) and phenyl-C61-butyric acid methylester (PCBM). Models and experiment have shown that the performance of polymer solar cells...

  2. Relating the morphology of poly(p-phenylene vinylene)/methanofullerene blends to solar-cell performance

    NARCIS (Netherlands)

    van Duren, JKJ; Yang, XN; Bulle-Lieuwma, CWT; Sieval, AB; Hummelen, JC; Janssen, RAJ; Yang, Xiaoniu; Bulle-Lieuwma, Corrie W.T.; Janssen, René A.J.

    2004-01-01

    The performance of bulk-heterojunction solar cells based on a phase-separated mixture of donor and acceptor materials is known to be critically dependent on the morphology of the active layer. Here we use a combination of techniques to resolve the morphology of spin cast films of poly(p-phenylene vi

  3. Unsymmetrical triphenylamine-oligothiophene hybrid conjugated systems as donor materials for high-voltage solution-processed organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ripaud, Emilie; Rousseau, Theodulf; Leriche, Philippe; Roncali, Jean [Group Linear Conjugated Systems, CNRS Moltech-Anjou, University of Angers, 2Bd Lavoisier, 49045 Angers (France)

    2011-07-15

    The synthesis of unsymmetrical triphenylamine-oligothiophene hybrid conjugated systems bearing dicyanovinyl electron acceptor end-groups is presented. When used as molecular donor materials in solution-processed bulk heteroj-unction solar cells, these compounds lead to efficient devices with very high open-circuit voltages. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Traveling solar-wind bulk-velocity fluctuations and their effects on electron heating in the inner heliosphere

    CERN Document Server

    Fahr, Hans J; Verscharen, Daniel

    2014-01-01

    Ambient plasma electrons undergo strong heating in regions associated with compressive traveling interplanetary solar-wind bulk-velocity jumps due to their specific interactions with the jump-inherent electric fields. After thermalization of this energy gain per shock passage through the operation of the Buneman instability, strong electron heating occurs that substantially influences the radial electron temperature profile. We describe the reduction of the jump amplitude due to energy expended by the traveling jump structure. We consider three effects; namely energy loss due to heating of electrons, energy loss due to work done against the pick-up-ion pressure gradient, and an energy gain due to nonlinear jump steepening. Taking these effects into account, we show that the decrease in jump amplitude with solar distance is more pronounced when the initial jump amplitude is higher in the inner solar system. Independent of the initial jump amplitude, it eventually decreases with increasing distance to a value o...

  5. Fabrication and Characterization of Organic Solar Cells

    OpenAIRE

    Yengel, Emre

    2010-01-01

    Bulk heterojunction organic solar cells have recently drawn tremendous attention because of their technological advantages for actualization of large-area and cost effective fabrication. Two important criteria of these cells are efficiency and cost. The research in this dissertation focuses on the enhancement of these criteria with two different approaches. In the first approach, power conversion efficiency of organic photovoltaic devices is enhanced by introducing Deoxyribonucleic acids DNA ...

  6. Application of highly-ordered TiO2 nanotube-arrays in heterojunction dye-sensitized solar cells

    Science.gov (United States)

    Paulose, Maggie; Shankar, Karthik; Varghese, Oomman K.; Mor, Gopal K.; Grimes, Craig A.

    2006-06-01

    Highly-ordered TiO2 nanotube arrays are made by potentiostatic anodization of a titanium film in a fluoride containing electrolyte. Here we describe the application of this unique material architecture in both front-side and back-side illuminated dye-sensitized solar cells (DSSCs). The back-side illuminated solar cells are based on the use of 6.2 µm long (110 nm pore diameter, 20 nm wall thickness) highly-ordered nanotube-array films made by anodization of a 250 µm thick Ti foil in a KF electrolyte. Front-side illuminated solar cells use a negative electrode composed of optically transparent nanotube arrays, approximately 3600 nm in length (46 nm pore diameter, 17 nm wall thickness), grown on a fluorine doped tin oxide coated glass substrate by anodic oxidation of a previously deposited RF-sputtered titanium thin film in a HF electrolyte. After crystallization by oxygen annealling the nanotube-arrays are treated with TiCl4 to enhance photocurrent amplitudes. The arrays are then sensitized by a self-assembled monolayer of bis(tetrabutylammonium)-cis-(dithiocyanato)-N, N'- bis(4-carboxylato-4'-carboxylic acid-2, 2'-bipyridine)ruthenium(II) (commonly called 'N719'). Superior photoresponse is obtained using acetonitrile as the dye solvent. Voltage decay measurements indicate that the highly-ordered TiO2 nanotube-arrays, in comparison with nanoparticulate systems, provide excellent pathways for electron percolation with superior electron lifetimes. The front-side illuminated DSSCs, show a typical AM 1.5 photocurrent of 10.3 mA cm-2, open circuit voltage of 0.84 V, 0.54 fill factor, and 4.7% efficiency although the transparent nanotube-array negative electrode is only 360 nm thick. The back-side illuminated DSSCs show an AM 1.5 short-circuit current density of 10.6 mA cm-2, 0.82 V open circuit potential and a 0.51 fill factor yielding a solar conversion efficiency of 4.4%.

  7. Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

    OpenAIRE

    Fatima Buny; Hamid Fardi

    2013-01-01

    Device simulation is used to investigate the current-voltage efficiency performance in CdTe/CdS photovoltaic solar cell. The role of several limiting factors such as back contact Schottky barrier and its relationship to the doping density and layer thickness is examined. The role of surface recombination velocity at back contact interface and extended CdTe layer is included. The base CdS/CdTe experimental device used in this study shows an efficiency of 16-17%. Simulation analysis is used to ...

  8. Characterization and Modeling of CdS/CdTe Heterojunction Thin-Film Solar Cell for High Efficiency Performance

    Directory of Open Access Journals (Sweden)

    Hamid Fardi

    2013-01-01

    Full Text Available Device simulation is used to investigate the current-voltage efficiency performance in CdTe/CdS photovoltaic solar cell. The role of several limiting factors such as back contact Schottky barrier and its relationship to the doping density and layer thickness is examined. The role of surface recombination velocity at back contact interface and extended CdTe layer is included. The base CdS/CdTe experimental device used in this study shows an efficiency of 16-17%. Simulation analysis is used to optimize the experimental base device under AM1.5 solar spectrum. Results obtained indicate that higher performance efficiency may be achieved by adding and optimizing an extended CdTe electron reflector layer at the back Schottky contact. In the optimization of the CdS/CdTe cell an extended electron reflector region with a barrier height of 0.1 eV and a doping density of  cm−3 with an optimum thickness of 100 nm results in best cell efficiency performance of 19.83% compared with the experimental data.

  9. Impact of Improved Solar Forecasts on Bulk Power System Operations in ISO-NE: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Brancucci Martinez-Anido, C.; Florita, A.; Hodge, B. M.

    2014-09-01

    The diurnal nature of solar power is made uncertain by variable cloud cover and the influence of atmospheric conditions on irradiance scattering processes. Its forecasting has become increasingly important to the unit commitment and dispatch process for efficient scheduling of generators in power system operations. This study examines the value of improved solar power forecasting for the Independent System Operator-New England system. The results show how 25% solar power penetration reduces net electricity generation costs by 22.9%.

  10. Recombination rates in heterojunction silicon solar cells analyzed by impedance spectroscopy at forward bias and under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Mora-Sero, Ivan; Luo, Yan; Garcia-Belmonte, Germa; Bisquert, Juan [Departament de Fisica, Universitat Jaume I, E-12071 Castello (Spain); Munoz, Delfina; Voz, Cristobal; Puigdollers, Joaquim; Alcubilla, Ramon [Departament d' Enginyeria Electronica, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)

    2008-04-15

    Impedance spectroscopy (at forward bias and under illumination) of solar cells comprised thin hydrogenated amorphous silicon (a-Si:H) films deposited on crystalline silicon (c-Si) wafers was analyzed in terms of ac equivalent circuits. Shockley-Read-Hall recombination at states on the device interfaces governs the cell dynamic response. Recombination process was modeled by means of simple RC circuits which allow to determine the capture rate of electrons and holes. Carrier lifetime is found to be stated by the electron capture time {tau}{sub SRH}{approx}{tau}{sub n}, and it results in the range of 300 {mu}s. The Al-annealed back contact was regarded as the dominating recombination interface. (author)

  11. Indan-1,3-dione electron-acceptor small molecules for solution-processable solar cells: a structure-property correlation.

    Science.gov (United States)

    Winzenberg, Kevin N; Kemppinen, Peter; Scholes, Fiona H; Collis, Gavin E; Shu, Ying; Singh, Th Birendra; Bilic, Ante; Forsyth, Craig M; Watkins, Scott E

    2013-07-18

    A structure-device performance correlation in bulk heterojunction solar cells for new indandione-derived small molecule electron acceptors, FEHIDT and F8IDT, is presented. Devices based on the former exhibit higher power conversion efficiency (2.4%) and higher open circuit voltage, a finding consistent with reduced intermolecular interactions. PMID:23739171

  12. Side-chain functionalized poly(3-hexylthiophene)-based copolymers: synsthesis and characterization of derivatives for application in polymer solar cells

    OpenAIRE

    CAMPO, Bert

    2009-01-01

    Conjugated polymers combine semi-conductive electrical properties with desirable mechanical properties such as light weight and high mechanical strength and flexibility. This enables the development of new technologies and applications based on these materials. Poly(3-hexylthiophene) is a conjugated polymer that has been extensively investigated in polymer:fullerene bulk heterojunction solar cells. ...

  13. ZnO-ZnTe Nanocone Heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hyun [ORNL; Smith, Barton [ORNL; Zhang, Xiaoguang [ORNL; Seo, Sung Seok A [ORNL; Bell, Zane W [ORNL; Xu, Jun [ORNL

    2010-01-01

    Semiconductor nanostructure heterojunctions are expected to be efficient structures for next-generation photovoltaic solar cells, radiation detectors, and light-emitting diodes. In this letter we report heterojunctions made of vertically aligned ZnO/ZnTe nanocones synthesized using a combination of thermal vapor deposition and pulsed-laser deposition (PLD). The ZnO nanocones and nanorods were synthesized as cores by utilizing the growth rate difference between central and boundary sites of precursor domains during thermal vapor deposition. The p-n heterojunctions were subsequently formed by growing ZnTe as shells on the nanocone surface using PLD. The ZnTe shells were polycrystalline structures, while ZnO cores were wurzite structures. The p-n junction of the nanocone core-shell structure exhibited I-V characteristics consistent with a p-n diode, but the nanorod junction did not. These structural and electric characteristics indicate that the ZnO nanocones are more feasible than ZnO nanorods as heterojunctions because the sloping facets of the nanocones facilitate deposition of ZnTe by PLD without the deleterious effects of shadowing. Furthermore, based on theoretical modeling of nanostructure heterojunctions, the nanocone-based junction exhibits an electrostatic potential profile that is much more effective for carrier transport than the electrostatic potential for the nanorod-based junction.

  14. Optical and Recombination Losses in Thin Film Solar Cells Based on Heterojunctions n-ZnS (n-CdS / p-CdTe with Current Collecting Contacts ITO and ZnO

    Directory of Open Access Journals (Sweden)

    O.A. Dobrozhan

    2014-11-01

    Full Text Available The optical and recombination losses in auxiliary and absorbing layers of solar cells based on heterojunctions n-ZnS / p-CdTe and n-CdS / p-CdTe with current collecting front sublayers ITO and ZnO were determined. As a result, spectral dependence of light transmittance (T of solar cells, taking into account its reflections from the boundaries of the contacting materials and in case of absorption in the auxiliary layers of solar cells was calculated. The influence of optical and recombination losses in the solar cell structure ITO (ZnO / CdS (ZnS / CdTe on the short circuit current (Jsc and efficiency (η of solar cells with different thickness of the window layer CdS (ZnS (50-300 nm and constant current collecting layer (200 nm was investigated. It has been established that the greatest efficiency values (15,9-16,1% solar cells have the structure of ZnO / ZnS / CdTe at a concentration of uncompensated acceptors in the absorbent layer (Na – Nd = 1015-1017 cm – 3 and the window layer thickness of 50 nm.

  15. Quantum dot size dependent J-V characteristics in heterojunction ZnO/PbS quantum dot solar cells.

    Science.gov (United States)

    Gao, Jianbo; Luther, Joseph M; Semonin, Octavi E; Ellingson, Randy J; Nozik, Arthur J; Beard, Matthew C

    2011-03-01

    The current-voltage (J-V) characteristics of ZnO/PbS quantum dot (QD) solar cells show a QD size-dependent behavior resulting from a Schottky junction that forms at the back metal electrode opposing the desirable diode formed between the ZnO and PbS QD layers. We study a QD size-dependent roll-over effect that refers to the saturation of photocurrent in forward bias and crossover effect which occurs when the light and dark J-V curves intersect. We model the J-V characteristics with a main diode formed between the n-type ZnO nanocrystal (NC) layer and p-type PbS QD layer in series with a leaky Schottky-diode formed between PbS QD layer and metal contact. We show how the characteristics of the two diodes depend on QD size, metal work function, and PbS QD layer thickness, and we discuss how the presence of the back diode complicates finding an optimal layer thickness. Finally, we present Kelvin probe measurements to determine the Fermi level of the QD layers and discuss band alignment, Fermi-level pinning, and the V(oc) within these devices.

  16. 纳米硅/晶体硅异质结太阳电池的优化设计%Optimization of nc-SiC : H(p)/c-Si(n) Heterojunction Solar Cells

    Institute of Scientific and Technical Information of China (English)

    汪礼胜; 祝霁沼; 陈凤翔

    2011-01-01

    采用AFORS-HET软件对TCO/nc-SiC∶H(p)/nc-Si∶H(i)/c-Si(n)/nc-Si∶H(n+)/Al异质结太阳电池进行了模拟,分别讨论了窗口层、本征层、界面态和背场对太阳电池性能参数的影响。模拟结果表明,厚度尽可能薄的p层能减少入射光及光生载流子在窗口层的损失,对应最佳的窗口层禁带宽度为1.95eV。本征层的引入主要是钝化异质结界面,降低界面态的影响,提高电池转换效率。合理的背场设计可提高电池的转换效率1.7个百分点左右,此时最佳的异质结太阳电池的性能参数为:开路电压Voc=696.1mV,短路电流密度Jsc=38.49mA/cm^2,填充因子FF=83.52%,转换效率η=22.38%。%High-efficiency TCO/nc-SiC : H(p)/nc-Si : H(i)/c-Si(n)/nc-Si : H(n^+)/Al heterojunction solar cells were simulated by AFORS-HET software. The effects of the emitter, intrinsic layer, interface density and back surface field (BSF) on the characteristics of solar cells were discussed. Simulation results show that the thinner p-type emitter is better for decreasing the loss of the incident light and photo-induced carrier in the emitter, and the corresponding optimal bandgap is 1. 95 eV. The introduction of the intrinsic layer is used to increase the conversion efficiency by passivating the hetero-junction interface and suppressing the interface states density. The conversion efficiency of well-designed hetero-junction solar cells with BSF is 1. 7% higher than that of the solar cells without BSF, and the optimum parameters are Voc=696.1 mV, Jsc=38.49 mA/cm^2 , FF=83.52%, η=22.38%.

  17. 氧化锌/氧化亚铜异质结太阳能电池的研究进展∗%Research Progress in Zinc Oxide/Cuprous Oxide Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    冯云珠; 董磊; 于良民

    2015-01-01

    Much attention recently has been paid on p-n heterojunction solar cells fabricated with cuprous oxide combined with zinc oxide owing to the advantage of favorable alignment of conductive band edges and lattice matching. The formation of heterojunctions can enhance the seperation of photoinduced electrons and holes,as well as the absor-bance of the light.This review compiles the main milestones reached during the last decades in the development of ZnO/Cu2 O heterojunction solar cells comprehensively.Different junction structures of these cells as planar and ZnO nanoarray based ones related to deposition sequences and synthesis methods are introduced separately,while photovol-taic property influence factors as well as improving methods are discussed.Considering the accomplishments achieved in a relatively short period of time,it can be said that this kind of solar cell can be promisingly applied in clean energy exploitation in the future,in spite of improvement of cell performance still in need.%因氧化亚铜(Cu2 O)、氧化锌(ZnO)能级和晶格匹配较好,近年来较多的研究者将两者复合制备异质结太阳能电池。异质结的形成可提高光生电子-空穴对的分离效率,同时拓展复合结构的光响应范围,从而有效提高太阳能电池性能。介绍了3类主流的 ZnO/Cu2 O 异质结结构,分别阐述主要的进展,综述了异质结结构中 Cu2 O、ZnO的制备方法以及制备条件对电池效率的影响,讨论了电池性能的改进措施,并对 ZnO/Cu2 O 异质结太阳能电池未来的发展前景进行展望。

  18. 利用铁电薄膜研究体异质结型有机光伏器件的光电流极性%Investigation on Photocurrent Polarity of a Bulk Heterojunction Organic Photovoltaic Device Using a Ferroelectric Thin Film

    Institute of Scientific and Technical Information of China (English)

    李博

    2012-01-01

    制备了铌镁酸铅-钛酸铅(PMN-PT)铁电薄膜,并通过紫外-可见(UV-Vis)透射光谱、X射线衍射(XRD)和原子力显微镜(AFM)对其进行了表征.为了研究体异质结型有机共混膜的光电流特性,制作了氧化铟锡(ITO)/PMN-PT/有机共混膜/铝(Al)的光伏器件,调制激光照射下外加偏压的极性和大小变化将直接改变瞬态光电流的极性和大小,从而可在实验上证明传统体异质结型有机光伏器件的光电流极性是由器件阴、阳电极的功函数差所导致的内建电场的方向决定.同时也提出了一种利用铁电薄膜来研究体异质结型有机光伏器件光电流特性的新方法.%The ferroelectric thin film of lead magnesium niobate-lead titanate (PMN-PT) was fabricated and characterized using UV-Vis transmission spectroscopy, X-ray diffraction (XRD), and atomic force microscopy (AFM). To determine the photocurrent properties of the bulk heterojunction organic blend film a photovoltaic device with the structure of tin indium oxide (ITO)/PMN-PT/organic blend film/aluminum (Al) was fabricated. Under modulated laser irradiation the amplitude and polarity of the transient photocurrent varied with the bias voltage, which shows that the photocurrent polarity of a conventional bulk heterojunction organic photovoltaic device is determined by the internal electric field that is induced by the difference between the work function of the anode and cathode electrodes. A new method is proposed for investigating the photocurrent properties of bulk heterojunction organic photovoltaic devices.

  19. Exciton-Dissociation and Charge-Recombination Processes in Pentacene/C 60 Solar Cells: Theoretical Insight into the Impact of Interface Geometry

    KAUST Repository

    Yi, Yuanping

    2009-11-04

    The exciton-dissociation and charge-recombination processes in organic solar cells based on pentacene/C60 heterojunctions are investigated by means of quantum-mechanical calculations. The electronic couplings and the rates of exciton dissociation and charge recombination have been evaluated for several geometrical configurations of the pentacene/C60 complex, which are relevant to bilayer and bulk heterojunctions. The results suggest that, irrespective of the actual pentacene-fullerene orientation, both pentacene-based and C60-based excitons are able to dissociate efficiently. Also, in the case of parallel configurations of the molecules at the pentacene/C60 interface, the decay of the lowest charge-transfer state to the ground state is calculated to be very fast; as a result, it can compete with the dissociation process into mobile charge carriers. Since parallel configurations are expected to be found more frequently in bulk heterojunctions than in bilayer heterojunctions, the performance of pentacene/C60 bulk-heterojunction solar cells is likely to be more affected by charge recombination than that of bilayer devices. © 2009 American Chemical Society.

  20. Fabrication and characterization of P3HT:PCBM-based thin film organic solar cells with zinc phthalocyanine

    Energy Technology Data Exchange (ETDEWEB)

    Maruhashi, Haruto, E-mail: oku@mat.usp.ac.jp; Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Suzuki, Atsushi, E-mail: oku@mat.usp.ac.jp; Akiyama, Tsuyoshi, E-mail: oku@mat.usp.ac.jp [The University of Shiga Prefecture, Hikone, Shiga 522-8533 (Japan); Yamasaki, Yasuhiro [Orient Chemical Industries Co., Ltd., Neyagawa, Osaka 572-8581 (Japan)

    2015-02-27

    [6,6]–phenyl C{sub 61}–butyric acid methyl ester and poly(3–hexylthiophene) bulk heterojunction solar cells added with zinc–tetra–tertiary–butyl–phthalocyanine (ZnPc) were fabricated and characterized. The photovoltaic properties of the solar cells with an inverted structure were improved by the ZnPc addition, which were investigated on the bases of current density–voltage characteristics, incident photon to current conversion efficiency.