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Sample records for bulk-heterojunction solar cells

  1. 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.

  2. 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...

  3. Polymer-fullerene bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Organic solar cells have the potential to be low-cost and efficient solar energy converters, with a promising energy balance. They are made of carbon-based semiconductors, which exhibit favourable light absorption and charge generation properties, and can be manufactured by low temperature processes such as printing from solvent-based inks, which are compatible with flexible plastic substrates or even paper. In this review, we will present an overview of the physical function of organic solar cells, their state-of-the-art performance and limitations, as well as novel concepts to achieve a better material stability and higher power conversion efficiencies. We will also briefly review processing and cost in view of the market potential.

  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. 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

  6. Bulk-heterojunction organic solar cells based on merocyanine colorants

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, Nils M.; Lademann, Hans W.A.; Meerholz, Klaus [Department fuer Chemie, Universitaet zu Koen (Germany); Buerckstuemmer, Hannah; Tulyakova, Elena V.; Deppisch, Manuela; Wuerthner, Frank [Institut fuer Organische Chemie, Universitaet Wuerzburg (Germany)

    2009-07-01

    To take advantage of the full potential of organic Bulk Heterojunction (BHJ) solar cells, there is a need to explore new materials. We introduced merocyanines dyes (MCs) as a new class of electron donor materials for the application in solution-processed BHJ solar cells. MCs are traditional low-molecular colorants that are widely applied in textile coloration, for printing purposes, and nonlinear optics. Due to their structure, consisting of an electron-donating and an electron-accepting subunit, they possess high absorption coefficients which is favorable for the use in solar cells. The vast variety of the MC synthesis allows for a variation of the absorption properties in a wide range and a tuning of the solar cell absorption to the emission spectrum of the sun. Another advantage of MCs compared to some long-wavelength absorbing polymers is the relatively low HOMO-energy (down to -6.0 eV), which is beneficial for large open-circuit voltages. We tested various different MC-dyes in the application as donor compound in BHJ solar cells in combination with the soluble C{sub 60} derivative PCBM. Power conversion efficiencies up to 2.1% under standard illumination and 2.7% at reduced intensities were achieved.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Effects of Germanium Tetrabromide Addition to Zinc Tetraphenyl Porphyrin / Fullerene Bulk Heterojunction Solar Cells

    Directory of Open Access Journals (Sweden)

    Atsushi Suzuki

    2014-03-01

    Full Text Available The effects of germanium tetrabromide addition to tetraphenyl porphyrin zinc (Zn-TPP/fullerene (C60 bulk heterojunction solar cells were characterized. The light-induced charge separation and charge transfer were investigated by current density and optical absorption. Addition of germanium tetrabromide inserted into active layer of Zn-TPP/C60 as bulk heterojunction had a positive effect on the photovoltaic and optical properties. The photovoltaic mechanism of the solar cells was discussed by experimental results. The photovoltaic performance was due to light-induced exciton promoted by insert of GeBr4 and charge transfer from HOMO of Zn-TPP to LUMO of C60 in the active layer.

  12. Investigating the role of efficiency enhancing interlayers for bulk heterojunction solar cells by scanning probe microscopy

    OpenAIRE

    DRIJKONINGEN, Jeroen; KESTERS, Jurgen; VANGERVEN, Tim; Bourgeois, Emilie; Lutsen, Laurence; Vanderzande, Dirk; Maes, Wouter; D'Haen, Jan; Manca, Jean

    2014-01-01

    Detailed optimization of the device architecture of bulk heterojunction organic solar cells is of crucial importance when eventually targeting commercial applications. It has been shown before that the efficiency of such devices can be increased significantly upon incorporation of an imidazolium-substituted polythiophene interlayer. The cause of this increase in efficiency was, however, still unclear and is investigated here by a combination of PeakForce Quantitative Nanomechanical Mapping...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. “Electrical annealing” effect in bulk heterojunction polymer solar cells

    International Nuclear Information System (INIS)

    The effect of electrical annealing treatment under different reverse bias on the performance of bulk heterojunction photovoltaic cells based on poly(3-hexylthiophene): 6,6-phenyl-C61-butyric acid methyl ester is explored. After electrical annealing at − 6 V, the polymer solar cell exhibits a 7.77 mA/cm2 short circuit current density, a 0.53 fill factor, and a 0.63 V open circuit voltage. A corresponding efficiency of 2.59% was achieved. In comparison, solar cell without electrical annealing exhibits power conversion efficiency of 2.37%. This enhanced efficiency is attributed to the modified orientation of the polymer chains inside the photoactive layer that increases the mobility of charge carriers. In addition, after electrical annealing, the Al cathode will penetrate further into the active layer increases the contact area and reduces the contact resistance. This Al penetration was confirmed by the depth profile of atomic concentration in the X-ray photoemission spectroscopy. - Highlights: ► Electrical annealing improves performance of bulk heterojunction photovoltaic cells. ► Enhanced efficiency attributed to modified orientation of polymer chains. ► Al penetration confirmed by X-ray photoemission spectroscopy depth profiles

  20. 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.

  1. 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.

  2. Polymer defect states modulate open-circuit voltage in bulk-heterojunction solar cells

    International Nuclear Information System (INIS)

    Defect states influence the operation of organic solar cells altering transport, recombination, and energetic mechanisms. This work investigates how processing conditions induce morphology-related, electrically active defects in the donor polymer of bulk-heterojunction solar cells. Structural order is inferred from absorption and X-ray diffraction data, while defect density is determined from capacitance methods. A correlation is observed between the polymer nanocrystallite size, the defect concentration, and the output voltage. For the case of poly(3-hexylthiophene), processing that promote crystallinity is beneficial for the device performance as it decreases the defect density (energy disorder) that finally enlarges the maximum achievable open-circuit voltage. Defect states within the effective bandgap modulate the downshift of the hole Fermi level upon illumination that in turn establishes the achievable open-circuit voltage

  3. Polymer defect states modulate open-circuit voltage in bulk-heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ripolles, Teresa S.; Guerrero, Antonio; Garcia-Belmonte, Germà, E-mail: garciag@uji.es [Photovoltaic and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, ES-12071 Castelló (Spain)

    2013-12-09

    Defect states influence the operation of organic solar cells altering transport, recombination, and energetic mechanisms. This work investigates how processing conditions induce morphology-related, electrically active defects in the donor polymer of bulk-heterojunction solar cells. Structural order is inferred from absorption and X-ray diffraction data, while defect density is determined from capacitance methods. A correlation is observed between the polymer nanocrystallite size, the defect concentration, and the output voltage. For the case of poly(3-hexylthiophene), processing that promote crystallinity is beneficial for the device performance as it decreases the defect density (energy disorder) that finally enlarges the maximum achievable open-circuit voltage. Defect states within the effective bandgap modulate the downshift of the hole Fermi level upon illumination that in turn establishes the achievable open-circuit voltage.

  4. 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%.

  5. 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

  6. 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.

  7. 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.

  8. Capacitance Voltage of P3HT:Graphene Nanocomposites Based Bulk-Heterojunction Organic Solar Cells

    Science.gov (United States)

    Shakina Mohd Shariff, Nur; Mohamad Saad, Puteri Sarah; Rusop Mahmood, Mohamad

    2015-11-01

    After the discovery of conjugated polymer and bulk-heterojunction concept, organic solar cell has gain many interest in the photovoltaic world. The main problem for organic solar cells is that the power conversion efficiency (PCE) is still considered low even though it is much more low cost compared to inorganic solar cell such as Silicon (Si). Therefore, the objective of this research is to investigate the effect of Poly(3-hexylthiophene) (P3HT) thickness and concentration towards the capacitance voltage of the P3HT:Graphene solar cells. A simulation software called SCAPS is used in this research to simulate the effect on the solar cells. SCAPS is specialized for photovoltaic simulation studies. The solar cell's structure will be drawn inside the simulation and the parameters for each layers is inserted. The voltage range will be fixed and the capacitance voltage will be calculated by the software and all the results will be put into one graph. For thickness results, P3HT's layer at a thickness of 100nm has the lowest value of capacitance and clearly shows a peak at 0.86V. Where for the concentration, 1×1016 cm-3 is the only value that clearly shows there is the built-in voltage (Vbi) in the solar cells. Therefore, P3HT's thickness of 100 nm and concentration of 1×1016 cm-3 has the best overall results.

  9. 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

  10. 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

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

    International Nuclear Information System (INIS)

    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

  12. 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.

  13. 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.

  14. Hydrogen-bonded oligothiophene rosettes with a benzodithiophene terminal unit: self-assembly and application to bulk heterojunction solar cells.

    Science.gov (United States)

    Ouchi, Hayato; Lin, Xu; Kizaki, Takahiro; Prabhu, Deepak D; Silly, Fabien; Kajitani, Takashi; Fukushima, Takanori; Nakayama, Ken-Ichi; Yagai, Shiki

    2016-06-14

    Benzodithiophene-functionalized oligothiophene with barbituric acid hydrogen-bonding unit self-assembles into nanoscopic structures via the formation of rosettes. The nanostructures show a power conversion efficiency of 3% upon mixing with PC61BM in bulk-heterojunction solar cells without thermal annealing. PMID:27251116

  15. 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.

  16. 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).

  17. Solution processable organic polymers and small molecules for bulk-heterojunction solar cells: A review

    International Nuclear Information System (INIS)

    Solution processed bulk heterojunction (BHJ) organic solar cells (OSCs) have gained wide interest in past few years and are established as one of the leading next generation photovoltaic technologies for low cost power production. Power conversion efficiencies up to 6% and 6.5% have been reported in the literature for single layer and tandem solar cells, respectively using conjugated polymers. A recent record efficiency about 8.13% with active area of 1.13 cm2 has been reported. However Solution processable small molecules have been widely applied for photovoltaic (PV) devices in recent years because they show strong absorption properties, and they can be easily purified and deposited onto flexible substrates at low cost. Introducing different donor and acceptor groups to construct donor--acceptor (D--A) structure small molecules has proved to be an efficient way to improve the properties of organic solar cells (OSCs). The power conversion efficiency about 4.4 % has been reported for OSCs based on the small molecules. This review deals with the recent progress of solution processable D--A structure small molecules and discusses the key factors affecting the properties of OSCs based on D--A structure small molecules: sunlight absorption, charge transport and the energy level of the molecules.

  18. Understanding the Effect of Unintentional Doping on Transport Optimization and Analysis in Efficient Organic Bulk-Heterojunction Solar Cells

    OpenAIRE

    Deledalle, Florent; Kirchartz, Thomas; Vezie, Michelle S.; Campoy-Quiles, Mariano; Shakya Tuladhar, Pabitra; Nelson, Jenny; Durrant, James R.

    2015-01-01

    In this paper, we provide experimental evidence of the effects of unintentional p-type doping on the performance and the apparent recombination dynamics of bulk-heterojunction solar cells. By supporting these experimental observations with drift-diffusion simulations on two batches of the same efficient polymer-fullerene solar cells with substantially different doping levels and at different thicknesses, we investigate the way the presence of doping affects the interpretation of optoelectroni...

  19. 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.

  20. P3HT/ZnO bulk-heterojunction solar cell sensitized by a perylene derivative

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingqing; Wang, Xiaogong [Department of Chemical Engineering, Laboratory for Advanced Materials, Tsinghua University, Beijing 100084 (China)

    2008-07-15

    In this work, a soluble perylene-derivative dye, N, N'-didodecyl-3,4,9,10-perylene tetracarboxylic diimide (PDI), was used to improve the photovoltaic performance of poly(3-hexylthiophene) (P3HT)/ZnO bulk heterojunction cells through blending with the composite. Results show that by incorporation of PDI in the P3HT/ZnO composite, the light absorption and exciton separation can be significantly improved. The photocurrent under white-light irradiation can be increased from 6.35 to 9.55 mA/cm{sup 2}. Solar decay experiment shows that V{sub OC} of the ITO/PEDOT:PSS/P3HT:ZnO:PDI/Al device decreases rapidly to almost zero in 1 h under persistent white-light illumination. After placing a 420 nm cutoff filter between the cell and the xenon lamp, the stability of the cell can be significantly improved. The device performance can maintain about 80% of the original value within 30 h and I{sub SC} degraded to zero after 142 h. The addition of PDI into the P3HT/ZnO device up to 5 wt% does not show observable effect on the solar cell decay behavior. (author)

  1. 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.

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

    International Nuclear Information System (INIS)

    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 (TiOx) 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

  3. 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)

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Electrical conductivity of chlorophyll with poly thiophene thin film as a bulk heterojunction solar cell

    International Nuclear Information System (INIS)

    Full text: In this work, electrical conductivity of the combinations mixture with different ratio of Poly thiophene (PT) and Chlorophyll (CHLO) thin film as a bulk heterojunction solar cell was studied. Spin coating technique was used to deposit the combination of PT and CHLO thin film on the Aurum (Au) layer which acts as a substrate. The optical characterization of thin film was measured using UV-Visible Spectrophotometer and four point probes were used to determine the film electrical properties in the dark and under the light. From the optical absorption study, the combination mixture between PT and CHLO altered the energy band gap of the thin film. The increasing of the mixture ratio of both solutions decreased the electrical conductivity in the dark and also under light. Under the light, the electrical conductivity of combine mixture shows the increasing with the increased of light intensity. The lowest mixture ratio shows the highest electrical conductivity ± 1.389 S/m under dark and increased with the increasing of the light intensity. (author)

  10. Optimization of characteristics of the j-v bulk heterojunction organic solar cells based on polymer/fullerene

    International Nuclear Information System (INIS)

    There are many models of optical and electrical that with them can be evaluated optical absorption and voltage - current properties in organic solar cells. Study of adsorption phenomena to an optical model and to achieve voltage-current characteristics is a new method for calculating the conversion efficiency that considered in this paper. In this study with this method is reviewed two bulk heterojunction structures based on polymer/fullerene and Power conversion efficiency in these structures has been compared with each other.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. 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

  16. 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.

  17. 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 ...

  18. 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.

  19. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    International Nuclear Information System (INIS)

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s

  20. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Hyun-Sik; Khang, Dahl-Young, E-mail: dykhang@yonsei.ac.kr

    2015-08-31

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s.

  1. Electron density profile at the interfaces of bulk heterojunction solar cells and its implication on the S-kink characteristics

    Science.gov (United States)

    Gusain, Abhay; Singh, Surendra; Chauhan, A. K.; Saxena, Vibha; Jha, P.; Veerender, P.; Singh, Ajay; Varde, P. V.; Basu, Saibal; Aswal, D. K.; Gupta, S. K.

    2016-02-01

    The efficiency of a bulk heterojunction (BHJ) solar cell critically depends upon quality of its interfaces. The imperfect interfaces can lead to S-kink in the current-voltage characteristics that reduce the efficiency of BHJ solar cells. In this letter, using PCDTBT:PCBM based BHJ solar cells, we demonstrate that non-destructive X-ray reflectivity is powerful technique to estimate the electron density profile across the BHJ solar cells. A direct correlation is observed between the enhanced electron density at PEDOT:PSS/PCDTBT:PCBM interface and appearance of S-kink in J-V characteristics, which is also supported by X-ray photoelectron spectroscopy and Kelvin probe measurements.

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

    Science.gov (United States)

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

    2016-05-01

    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. PMID:26468898

  3. 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.

  4. 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.

  5. Spectral sensitivity dependence on the details of preparation for P3HT:PCBM bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    The performance of bulk heterojunction P3HT :PCBM polymer solar cells is studied using current-voltage and spectral sensitivity measurements. Front transparent contacts of either ITO or a sputtered multilayer TiO2/Ag/TiO2 transparent conductive electrode are applied. Thin PEDOT:PSS and P3HT:PCBM polymer layers are deposited on these substrates by spin coating. The degradation of the solar cells is studied by subjecting them to UV irradiation. The obtained spectral sensitivity curves are analyzed in comparison with the optical absorption spectra of the transparent electrodes and active layers employed. It is observed that there is a pronounced dependence of the spectral sensitivity curves on the thermal treatment and UV irradiation applied to the solar cells. The performance of the multilayer TiO2/Ag/TiO2 transparent conductive electrodes is also studied in comparison with that of the ITO ones

  6. Spectroscopic investigation of charge injection process in the bulk-heterojunction P3HT:PCBM solar cell

    International Nuclear Information System (INIS)

    The effect of charge injection in solar cells is usually difficult to examine although it is expected to highly affect the solar cell operation. The effect of charge injection on the operation of bulk-heterojunction (BHJ) solar cells made from blend films of poly(3-hexylthiophene) (P3HT) and methanofullerene (PCBM) is studied using a spectroscopic technique combined with modulation of applied bias, termed a device modulation (DM) spectroscopic technique. The DM measurements enable selective detection of spectroscopic signals from injected P3HT polarons. The voltage dependent-DM measurements in the dark condition reveal the starting point bias of charge injection (∝0 V) and the voltage-dependence of the polaron density, directly from the spectroscopic signals. The frequency dependence of DM signals in the dark condition demonstrates that a bimolecular recombination process dominates the loss mechanism for the injected polarons (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Effect of light incidence angle on optical absorption characteristics of low bandgap polymer-based bulk heterojunction organic solar cells

    Science.gov (United States)

    Lee, Kwan-Yong; Park, Sun-Joo; Kim, Do-Hyun; Kim, Young-Joo

    2014-08-01

    The bulk heterojunction organic solar cell based on thieno[3,4-b]thiophene/benzodithiophene (PTB7) is one of an alternative candidate for traditional silicon-based solar cells owing to its advantages of ease of manufacture, low cost, and flexibility. Currently, many research studies of these devices focus on power conversion efficiency (PCE) enhancement with only normal sunlight incidence. In this study, we have experimentally verified that PCE markedly decreased from 5.51 to 3.47% as incidence angle was changed from 0 to 60°. Using the finite-difference time-domain method, we found that the degeneration of optical absorption is caused by the decreased electrical field intensity in the photoactive layer over the entire wavelength range due to the optical interference profile change. In addition, we confirmed that a higher incidence angle also results in unbalanced charge carrier transport characteristics, resulting in further decrease in solar cell efficiency.

  8. 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)

  9. 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)

  10. 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

  11. 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.

  12. A new terthiophene-thienopyrrolodione copolymer-based bulk heterojunction solar cell with high open-circuit voltage

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Jang; Leong, Wei Lin; Yuen, Jonathan D.; Moon, Ji Sun; Heeger, Alan J. [Center for Polymers and Organic Solids, University of California, Santa Barbara, Santa Barbara, CA 93106-5090 (United States); Pron, Agnieszka; Berrouard, Philippe; Leclerc, Mario [Department of Chemistry, Universite Laval, Quebec City, QC, G1V 0A6 (Canada)

    2012-11-15

    A new semiconducting polymer based on terthiophene-thienopyrrolodione alternating building blocks with a deep HOMO energy level (5.66 eV) is presented. The polymer is prepared by a direct heteroarylation polycondensation reaction, which is a low-cost and green alternative to the standard Stille coupling reaction and thus avoids any use of toxic stannyl derivatives. Integrating the polymer into bulk heterojunction solar cells with [6,6]-phenyl C71-butyric acid methyl ester ([70]PCBM) leads to a PCE of over 6% and a high open-circuit voltage of up to 0.94 V. To obtain these results a unique processing additive, 1-chloronaphthalene, is used, and a relatively low concentration of [70]PCBM is used in the blend solution. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. 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.

  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. 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

  16. 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

  17. 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.

  18. Photogeneration process in bulk heterojunction solar cell based on quaterthiophene and CdS nanoparticles

    Science.gov (United States)

    Benchaabane, Aida; Hamed, Zied Ben; Kouki, Fayçal; Zeinert, Andreas; Bouchriha, Habib

    2015-09-01

    In this paper, the blended systems composed of organic oligothiophenes and CdS nanoparticles were investigated through their optical and photoelectrical measurements for their potential applications in photovoltaic devices. The electrical and photoelectrical properties of the devices fabricated with the active layer sandwiched between the metal anode and the metal cathode have been reported. Dependence of the performance of this bulk heterojunction photovoltaic device on their composition has been investigated with respect to charge transport. The organic/inorganic interface area in bulk heterojunction is an important factor in the photovoltaic process. The incorporation of nanoparticles in the polymer matrix, for the purpose to fabricate hybrid inorganic-organic materials, could be a good alternative to enhance the charge generation process of free carriers. The J- V curves of the quaterthiophene (4T) and hybrid quaterthiophene/cadmium sulfide nanoparticles CdS show the important role played by the nanoparticles for energy conversion improvement. The experimental data were found to be in good agreement with a modified Braun-Onsager model.

  19. Understanding the Role of Additives in Improving the Performance of Polymer:Fullerene Bulk Heterojunction Solar Cells

    Science.gov (United States)

    Chen, Wei

    2014-03-01

    Solar cells based on the polymer:fullerene bulk heterojunction (BHJ) represent one of the most promising technologies for next-generation solar energy conversion due to their low-cost and scalability. In the last fifteen years, research efforts have led to organic photovoltaic (OPV) devices with power conversion efficiencies (PCEs) ~ 12%, but these values are still insufficient for the devices to become widely marketable. To further improve solar cell performance, a thorough understanding of the complex processing-structure-performance relationships in OPV devices is required. Recently, the use of processing additives have been proved to be one of the most effective methods to tune the nanomorphology of polymer:fullerene active layer, as the incorporation of a small percentage of solvent additives results in a nearly doubling of device efficiency. However, the physics behind these improved performances by processing additives still remains unclear. In this work, by taking advantage of resonant soft x-ray scattering (RSoXS) and energy-filtered transmission electron microscopy (EFTEM), we have determined that the solvent additives induce the change in the formation mechanism of polymer:fullerene nanomorphologies in the process of film casting. Progress established in the course of these studies on structural and morphological characterizations will serve as the foundation for further improving the efficiency of polymer solar cells to realize their large-scale commercial use.

  20. P3HT/TiO{sub 2} bulk-heterojunction solar cell sensitized by a perylene derivative

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingqing; Wang, Xiaogong [Department of Chemical Engineering, Laboratory for Advanced Materials, Tsinghua University, Beijing 100084 (China)

    2007-11-23

    In this work, a new type of dye-sensitized bulk-heterojunction hybrid solar cells has been developed. The heterojunction films were prepared to contain poly(3-hexylthiophene) (P3HT), N,N'-diphenyl glyoxaline-3,4,9,10-perylene tetracarboxylic acid diacidamide (PDI) and TiO{sub 2}. In the architecture, TiO{sub 2} and P3HT were designed to act as the electron acceptor and donor. PDI was used as sensitizer to enhance the photon absorption. Results showed that by incorporation of PDI in the P3HT/TiO{sub 2} composite, the light absorption, exciton separation and photocurrent under white light were dramatically enhanced. Solar decay analyses showed that devices contained TiO{sub 2} required 12 h to obtain maximum current density and the addition of PDI did not affect the solar decay behavior and stability of device composed of P3HT/TiO{sub 2}. The devices of P3HT, P3HT/TiO{sub 2}, P3HT/TiO{sub 2}/PDI could work for 5, 42, 45 h under continuous white light illumination (100 mW/m{sup 2}) under the ambient condition. (author)

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Current-voltage characteristics of bulk heterojunction organic solar cells: connection between light and dark curves

    Energy Technology Data Exchange (ETDEWEB)

    Boix, Pablo P.; Guerrero, Antonio; Garcia-Belmonte, Germa; Bisquert, Juan [Photovoltaic and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, ES-12071 Castello (Spain); Marchesi, Luis F. [Laboratorio Interdisciplinar de, Eletroquimica e Ceramica (LIEC), Universidade Federal de Sao Carlos (Brazil); Photovoltaic and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, ES-12071 Castello (Spain)

    2011-11-15

    A connection is established between recombination and series resistances extracted from impedance spectroscopy and current-voltage curves of polythiophene:fullerene organic solar cells. Recombination is shown to depend exclusively on the (Fermi level) voltage, which allows construction of the current-voltage characteristics in any required conditions based on a restricted set of measurements. The analysis highlights carrier recombination current as the determining mechanism of organic solar cell performance. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. 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)

  18. Morphology versus vertical phase segregation in solvent annealed small molecule bulk heterojunction organic solar cells

    Czech Academy of Sciences Publication Activity Database

    Kovalenko, A.; Stoyanova, V.; Pospisil, J.; Zhivkov, I.; Fekete, Ladislav; Karashanova, D.; Kratochvílová, Irena; Vala, M.; Weiter, M.

    2015-01-01

    Roč. 2015, Oct (2015), s. 238981. ISSN 1110-662X R&D Projects: GA ČR(CZ) GA15-05095S; GA TA ČR TA04020156; GA MŠk LO1409 Institutional support: RVO:68378271 Keywords : organic solar cells Subject RIV: JJ - Other Materials Impact factor: 1.563, year: 2014

  19. 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....

  20. 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.

  1. 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

  2. Enhancement of power conversion efficiency of bulk-heterojunction polymer solar cells by plasmonic gold nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Pfleger, Jiří; Tran, V. S.; Halašová, Klára; Kazim, Samrana; Šlouf, Miroslav

    Thessaloniki: Laboratory for Thin Films Nanosystems and Nanometrology, Physics Department, Aristotle University of Thessaloniki, 2012. s. 80. [International Symposium on Flexible Organic Electronics /5./ - ISFOE12. 02.07.2012-05.07.2012, Thessaloniki] R&D Projects: GA ČR GAP208/10/0941; GA MŠk 7E10040 EU Projects: European Commission(XE) 247745 - FlexNet Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : nanoparticles * polymer * solar cells Subject RIV: CF - Physical ; Theoretical Chemistry

  3. 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...

  4. 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.

  5. Photovoltaic properties of bulk heterojunction solar cells with improved spectral coverage

    International Nuclear Information System (INIS)

    The potential of dye sensitization of organic solar cells has been investigated. The electrical and photoelectrical properties of such devices have been studied. The architecture of the solar cell is based on spin-coated thin films of MEH-PPV sensitized with Hydrogen Phthalocyanine (PcH2) and Coumarin 343 dyes, which are sandwiched between indium tin oxide (ITO)-coated glass and aluminium electrodes. By adding PcH2 and Coumarin 343 to the MEH-PPV active layer the width of absorption spectrum increases drastically. Introduction of a methine unit (-CH=CH-) connecting the cyano (-CN) and carboxyl (-COOH) groups into the Coumarin 343 framework expanded the π - conjugated in the dye and thus resulted in a wide absorption in the visible region. The sensitization of the MEH-PPV thin film by PcH2 and Coumarin 343 dyes leads to photoluminescence (PL) enhancement whereas the incorporation of fullerene molecules (C6) in the blend, acting as electron acceptors, induces PL quenching due to the separation of the photogenerated charges. Photocurrent enhancement and increase of the open circuit voltage are induced by dye sensitization of MEH-PPV/C6 blends

  6. 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.

  7. 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

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

    Directory of Open Access Journals (Sweden)

    Wang Yan

    2009-01-01

    Full Text Available 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 different ZnCdTe:[MEH-PPV + C60] weight ratios of 10 wt% (D1–1, 20 wt% (D1–2, 40 wt% (D1–3, and 70 wt% (D1–4, it was found that the device D1–3exhibits the best performance. The power conversion efficiency (η is improved doubly compared with that of the MEH-PPV:C60device.

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

    International Nuclear Information System (INIS)

    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/cm2). 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/cm2, an open-circuit voltage of 0.67 V, and a fill factor of 0.46, under AM 1.5 illumination (100 mW/cm2). - 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%

  10. 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.

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

    OpenAIRE

    Abdulra'uf Lukman Bola; Habibun Nabi Muhammad Ekramul Mahmud; Rosiyah Yahya; Wasiu Adebayo Hammed

    2013-01-01

    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 im...

  12. Interface and charge transport studies in organic solar cells based on P3HT:PCBM bulk heterojunctions

    Science.gov (United States)

    Rujisamphan, Nopporn

    Interfaces and charge transport in organic solar cells based on P3HT:PCBM bulk heterojunctions (BHJ) were studied. State-of-the-art TEM sample preparation techniques, including in-situ lift-out, were used with a dual focused ion beam (FIB) system on a typical device (ITO/PEDOT:PSS/P3HT:PCBM/Al). Through bright field (BF) TEM micrographs a mixed layer between the Al electrode and the organic active layer (P3HT:PCBM) was clearly observed in both as-fabricated and annealed devices. The effect of Al contact resistance before and after annealing was studied using the vertical transmission line model (TLM). It was found that by annealing after Al evaporation, the contact resistivity decreased by 38%. Energy filtered transmission electron microscopy (EFTEM) clearly revealed a nanoscopic phase separation. From the EFTEM images, the average length and the diameter of P3HT fibrils were found to be approximately 70 nm and 15 nm, respectively. Combining the EFTEM, selected area electron diffraction (SAED) patterns and X-ray diffraction (XRD) results, the number and spacing of the ordered polymer chains in P3HT fibrils were calculated. There were about 18 repeating units of P3HT perpendicular to the fibril, about 184 layers of pi-pi* stacking along the fibril and about 9 layers of interchain stacking within the fibril. Accompanied by cross-section samples prepared by the FIB technique, the vertical morphology of each phase was analyzed. By collecting 30 eV energy loss images, the phase separation in the blend of P3HT:PCBM was distinguishable. A higher P3HT concentration was observed at the top of the cell. The temperature dependent charge separation and charge transport were studied using modulated surface photovoltage spectroscopy (SPV) on layers of P3HT, PCBM, and the blend. The unchanged character of the SPV spectra on the P3HT provides evidence that the mechanisms of charge separation, recombination and charge transport does not change qualitatively after cooling. It was

  13. 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.

  14. Fabrication and Characterization of Fullerene-Based Bulk Heterojunction Solar Cells with Porphyrin, CuInS2, Diamond and Exciton-Diffusion Blocking Layer

    Directory of Open Access Journals (Sweden)

    Takeo Oku

    2010-04-01

    Full Text Available Fullerene-based bulk heterojunction solar cells were fabricated, and the electronic and optical properties were investigated. C60 were used as n-type semiconductors, and porphyrin, CuInS2 and diamond were used as p-type semiconductors. An effect of exciton-diffusion blocking layer of perylene derivative on the solar cells between active layer and metal layer was also investigated. Optimized structures with the exciton-diffusion blocking layer improved conversion efficiencies. Electronic structures of the molecules were investigated by molecular orbital calculation, and energy levels of the solar cells were discussed. Nanostructures of the solar cells were investigated by transmission electron microscopy, electron diffraction and X-ray diffraction, which indicated formation of mixed nanocrystals.

  15. 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).

  16. Modeling of Open-Circuit Voltage of Phenyl-C61-Butyric Acid Methyl Ester-Like Based Bulk-Heterojunction Solar Cells.

    Science.gov (United States)

    Ferreira, Rodrigo M; Batagin-Neto, Augusto; Lavarda, Francisco C

    2015-12-01

    New materials are currently being sought for use in active layers of bulk-heterojunction organic solar cells, and computational modeling plays an important role in this search. Although open circuit voltage (V(oc)) is one of the fundamental quantities that determine the efficiency of a solar cell, there is no consensus on the best way to estimate this magnitude for new materials from calculations of the electronic structure. In this paper, we compare ways of predicting V(oc) values employing a diverse group of blends and conclude that it is possible to have a good prediction tool for organic solar cells based on phenyl-C61-butyric acid methyl ester (PCBM) acceptor molecules. PMID:26682440

  17. 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

  18. Molecular packing and electronic processes in amorphous-like polymer bulk heterojunction solar cells with fullerene intercalation.

    Science.gov (United States)

    Xiao, Ting; Xu, Haihua; Grancini, Giulia; Mai, Jiangquan; Petrozza, Annamaria; Jeng, U-Ser; Wang, Yan; Xin, Xin; Lu, Yong; Choon, Ng Siu; Xiao, Hu; Ong, Beng S; Lu, Xinhui; Zhao, Ni

    2014-01-01

    The interpenetrating morphology formed by the electron donor and acceptor materials is critical for the performance of polymer:fullerene bulk heterojunction (BHJ) photovoltaic (PV) cells. In this work we carried out a systematic investigation on a high PV efficiency (>6%) BHJ system consisting of a newly developed 5,6-difluorobenzo[c] thiadiazole-based copolymer, PFBT-T20TT, and a fullerene derivative. Grazing incidence X-ray scattering measurements reveal the lower-ordered nature of the BHJ system as well as an intermixing morphology with intercalation of fullerene molecules between the PFBT-T20TT lamella. Steady-state and transient photo-induced absorption spectroscopy reveal ultrafast charge transfer (CT) at the PFBT-T20TT/fullerene interface, indicating that the CT process is no longer limited by exciton diffusion. Furthermore, we extracted the hole mobility based on the space limited current (SCLC) model and found that more efficient hole transport is achieved in the PFBT-T20TT:fullerene BHJ as compared to pure PFBT-T20TT, showing a different trend as compared to the previously reported highly crystalline polymer:fullerene blend with a similar intercalation manner. Our study correlates the fullerene intercalated polymer lamella morphology with device performance and provides a coherent model to interpret the high photovoltaic performance of some of the recently developed weakly-ordered BHJ systems based on conjugated polymers with branched side-chain. PMID:24909640

  19. Spray pyrolysed In2S3 thin films: A potential electron selective layer for large area inverted bulk-heterojunction polymer solar cells

    International Nuclear Information System (INIS)

    In this paper, we report the results of investigations on the potential of spray pyrolysis technique in depositing electron selective layer over larger area for the fabrication of inverted bulk-heterojunction polymer solar cells. The electron selective layer (In2S3) was deposited using spray pyrolysis technique and the linear heterojunction device thus fabricated exhibited good uniformity in photovoltaic properties throughout the area of the device. An MEH-PPV:PCBM inverted bulk-heterojunction device with In2S3 electron selective layer (active area of 3.25 x 3.25 cm2) was also fabricated and tested under indoor and outdoor conditions. From the indoor measurements employing a tungsten halogen lamp (50 mW/cm2 illumination), an open-circuit voltage of 0.41 V and a short-circuit current of 5.6 mA were obtained. On the other hand, the outdoor measurements under direct sunlight (74 mW/cm2) yielded an open-circuit voltage of 0.46 V and a short-circuit current of 9.37 mA. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Impact of the energy difference in LUMO and HOMO of the bulk heterojunctions components on the efficiency of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Derouiche, H. [ISSTE, Technopole de Borj-Cedria. B.P. 95, 2050 Hammam-Lif (Tunisia); Djara, V. [LPSE-FSTN, 2 Rue de la Houssiniere, BP 92208, Nantes Cedex 3, 44322 (France)

    2007-08-15

    The characteristics of two bulk heterojunctions photovoltaic devices composed of zinc phthalocyanine (ZnPc) as electron donor and as electron acceptor, for which we used perylene tetracarboxylic dianhydrid (PTCDA) or 1,4-diaminoanthraquinone (1,4-DAAQ) having been studied. Organic semiconductor-blended films were formed by highvacuum co-evaporation. To study the properties of the different samples, the films were characterized by optical absorption, scanning electron microscopy (SEM) measurements, and solar cell I-V measurements, AM1.5 (1000 W/m{sup 2}) irradiance. Theoretical and experimental results have shown that a better efficiency is obtained in blending ZnPc with PTCDA more than with 1,4-DAAQ. The offset of the band edges of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the blended components will prove responsible for the improvement of all photovoltaic properties of the organic solar cells. (author)

  1. 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.

  2. 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...

  3. Effects of acetone-soaking treatment on the performance of polymer solar cells based on P3HT/PCBM bulk heterojunction

    International Nuclear Information System (INIS)

    The improvement of the acetone-soaking treatment to the performance of polymer solar cells based on the P3HT/PCBM bulk heterojunction is reported. Undergoing acetone-soaking, the PCBM does not distribute uniformly in the vertical direction, a PCBM enrichment layer forms on the top of the active layer, which is beneficial to the collection of the carriers and blocking the inverting diffusion carriers. X-ray photoelectron spectroscopy (XPS) analysis reveals that the PCBM weight ratio on the top of the active layer increases by 20% after the acetone-soaking treatment. Due to the nonuniform distribution of PCBM, the short-circuit current density, the open-circuit voltage, and the fill factor are enhanced significantly. Finally, the power conversion efficiency of the acetone-soaking device increases by 31% compared with the control device. (interdisciplinary physics and related areas of science and technology)

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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%.

  11. Modeling the increased efficiency due to light scattering effects in conjugated polymer/fullerene-based bulk heterojunction solar cells

    Czech Academy of Sciences Publication Activity Database

    Purkrt, Adam; Špringer, Jiří; Poruba, Aleš; Vaněček, Milan; Goris, L.; Haenen, K.; Nesladek, M.; Vandewal, K.; Manca, J.; Vanderzande, D.

    Munich: WIP-Renewable Energies, 2005 - (Palz, W.; Ossenbrink, H.; Helm, P.), s. 362-365 ISBN 3-936338-19-1. [European Photovoltaic Solar Energy Conference /20./. Barcelona (ES), 06.06.2005-10.06.2005] R&D Projects: GA MŽP(CZ) SN/320/11/03 Institutional research plan: CEZ:AV0Z10100521 Keywords : organic solar cell * light trapping * modeling Subject RIV: BM - Solid Matter Physics ; Magnetism

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Effect of simultaneous electrical and thermal treatment on the performance of bulk heterojunction organic solar cell blended with organic salt

    Energy Technology Data Exchange (ETDEWEB)

    Sabri, Nasehah Syamin; Yap, Chi Chin; Yahaya, Muhammad [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Salleh, Muhamad Mat [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    This work presents the influence of simultaneous electrical and thermal treatment on the performance of organic solar cell blended with organic salt. The organic solar cells were composed of indium tin oxide as anode, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]: (6,6)-phenyl-C61 butyric acid methyl ester: tetrabutylammonium hexafluorophosphate blend as organic active layer and aluminium as cathode. The devices underwent a simultaneous fixed-voltage electrical and thermal treatment at different temperatures of 25, 50 and 75 °C. It was found that photovoltaic performance improved with the thermal treatment temperature. Accumulation of more organic salt ions in the active layer leads to broadening of p-n doped regions and hence higher built-in electric field across thin intrinsic layer. The simultaneous electrical and thermal treatment has been shown to be able to reduce the electrical treatment voltage.

  19. 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.

  20. 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.

  1. A novel fabrication of MEH-PPV/Al:ZnO nanorod arrays based ordered bulk heterojunction hybrid solar cells

    International Nuclear Information System (INIS)

    Vertically aligned Al:ZnO nanorod arrays has been used as window layer in the fabrication of ordered bulk heterojuction hybrid solar cells. The utilization of the nanorod arrays will enhance the electron transport in vertical direction and also for light harvesting applications for high performance devices. The performance of this hybrid polymer/metal oxide photovoltaic devices based on MEH-PPV [poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene)] and oriented Al:ZnO nanorod arrays is studied. The Al:ZnO nanorod arrays with a diameter of about 70–80 nm and thickness of approximately 500 nm were successfully grown on Al:ZnO-coated ITO substrate by sonicated sol–gel immersion technique. The photovoltaic performance of a short-circuit current density of 5.320 mA/cm2, an open-circuit voltage of 195 mV and a fill factor of 27.71%, with a power conversion efficiency of about 0.287% under AM 1.5 illumination (100 mW/cm2). To the best of our knowledge, preparation of aligned Al:ZnO nanorod arrays for this type of solar cell fabrication has not been reported by any research group.

  2. Influence of Surface Recombination on Charge-Carrier Kinetics in Organic Bulk Heterojunction Solar Cells with Nickel Oxide Interlayers

    Science.gov (United States)

    Wheeler, Scot; Deledalle, Florent; Tokmoldin, Nurlan; Kirchartz, Thomas; Nelson, Jenny; Durrant, James R.

    2015-08-01

    The choice of electrode for organic photovoltaics is known to be of importance to both device stability and performance, especially regarding the open-circuit voltage (VOC ). Here we show that the work function of a nickel oxide anode, varied using an O2 plasma treatment, has a considerable influence on the open-circuit voltage VOC of an organic solar cell. We probe recombination in the devices using transient photovoltage and charge extraction to determine the lifetime as a function of charge-carrier concentration and compare the experimental results with numerical drift-diffusion simulations. This combination of experiment and simulations allows us to conclude that the variations in VOC are due to a change in surface recombination, localized at the NiO anode, although only a small change in carrier lifetime is observed.

  3. The dependence of the cathode architecture on the photoactive layer morphology in bulk-heterojunction polymeric solar cells

    International Nuclear Information System (INIS)

    Poly (3-hexylthiophene) (P3HT), [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and polymethylmethacrylate (PMMA) have been chosen to prepare binary and ternary blend thin films. In the case of the binary blend thin films of P3HT:PCBM used as the photoactive layers, the LiF/Al cathode offered nearly the same power conversion efficiency (PCE) as bathocuproine (BCP) 2 nm Al−1 and BCP 10 nm Al−1 cathodes. While ternary blend thin films of P3HT:PCBM:PMMA were applied as the photoactive layers, the BCP 2 nm Al−1 cathode showed an increase of roughly 42% in the PCE relative to ternary blend thin film with LiF/Al and BCP 10 nm Al−1 cathodes. The vertical phase separation of P3HT and PCBM was found to be more suppressed in the ternary blend films than in the binary ones, due to the confinement of PMMA. The P3HT:PCBM:PMMA with the BCP 2 nm Al−1 cathode showed an increase of 20% in the PCE as compared to the binary thin film of P3HT:PCBM with the LiF/Al cathode. We provide some insights into the correlation between the morphology control of active layer and cathode structure, useful for the development of polymeric solar cells towards the commercialization. (paper)

  4. 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.

  5. Effect of solvent additives and P3HT on PDTSTTz/PCBM-based bulk heterojunction solar cells

    Science.gov (United States)

    Ergete, Assegid; Sabir, Fedlu K.; Li, Yongfang; Yohannes, Teketel

    2015-01-01

    In this investigation, photovoltaic (PV) parameters improvements in poly[2,6-(4,4‧-bis(2-ethylhexyl)dithieno[3,2-b:2‧,3‧-d]silole)-alt-5,5‧-(3,6-bis[4-(2-ethylhexyl)thienyl-2-yl]-s-tetrazine] and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PDTSTTz:PCBM) blend were made through solvent additives and secondary donor addition. Short carbon chain solvent additives such as iodomethane (IMe), iodoethane (IEt), iodobutane (IBu), and diiodomethane (DIMe) were used. The results have shown that the short circuit current density (Jsc), as well as power conversion efficiency (PCE) of PDTSTTz:PCBM blend cell increased with the increase in length of carbon chains of the additives. IBu, with relatively the longest carbon chain, has better performance-improving impact than IMe (with the shortest carbon chain). The same trend was observed for fill factor. The other PV parameter, open circuit voltages (Voc), did not show significant change following these solvent additives. The effect of a secondary (additional) donor on the PDTSTTz/PCBM system was investigated by adding different proportions of poly(3-hexylthiophene-2,5-diyl) (P3HT). Because P3HT (secondary donor) and PDTSTTz (hosting donor) complement each other in light absorption, the PDTSTTz/PCBM system containing an optimum proportion of P3HT could provide a wider range of light absorption, and as a result it exhibited a higher short circuit current (11.08 mA/cm2) and then a PCE of 2.42%.

  6. 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)

  7. 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.

  8. 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

  9. Interface-engineering additives of poly(oxyethylene tridecyl ether) for low-band gap polymer solar cells consisting of PCDTBT:PCBM₇₀ bulk-heterojunction layers.

    Science.gov (United States)

    Huh, Yoon Ho; Park, Byoungchoo

    2013-01-14

    We herein report on the improved photovoltaic (PV) effects of using a polymer bulk-heterojunction (BHJ) layer that consists of a low-band gap electron donor polymer of poly(N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)) (PCDTBT) and an acceptor of [6,6]-phenyl C₇₁ butyric acid methyl ester (PCBM₇₀), doped with an interface-engineering surfactant additive of poly(oxyethylene tridecyl ether) (PTE). The presence of an interface-engineering additive in the PV layer results in excellent performance; the addition of PTE to a PCDTBT:PCBM₇₀ system produces a power conversion efficiency (PCE) of 6.0%, which is much higher than that of a reference device without the additive (4.9%). We attribute this improvement to an increased charge carrier lifetime, which is likely to be the result of the presence of PTE molecules oriented at the interfaces between the BHJ PV layer and the anode and cathode, as well as at the interfaces between the phase-separated BHJ domains. Our results suggest that the incorporation of the PTE interface-engineering additive in the PCDTBT:PCBM₇₀ PV layer results in a functional composite system that shows considerable promise for use in efficient polymer BHJ PV cells. PMID:23389265

  10. 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.

  11. Driving vertical phase separation in a bulk-heterojunction by inserting a poly(3-hexylthiophene) layer for highly efficient organic solar cells

    International Nuclear Information System (INIS)

    A desirable vertical phase separation of a bulk-heterojunction was achieved by inserting a P3HT layer between the blend layer and the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) layer. According to the high (PEDOT:PSS) and low (P3HT) surface energies of substrate, it might be possible to modulate the vertical phase separation in the bulk-heterojunction. The result of vertical phase separation was determined using time-of-flight secondary-ion mass spectroscopy analysis. A controlled thickness of 50 nm for the inserted P3HT layer prevented undesirable light absorption and the power conversion efficiency of this condition was increased by 44% compared to that of a reference device.

  12. 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

  13. 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.

  14. 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.

  15. Modelling the current density increase due to the "light-trapping" effect in conjugated polymer/fullerene-based bulk heterojunction solar cells

    Czech Academy of Sciences Publication Activity Database

    Purkrt, Adam; Špringer, Jiří; Poruba, Aleš; Vaněček, Milan; Goris, L.; Manca, J.

    Gent: Academia Press, 2007 - (Burgelman, M.), s. 133-139 ISBN 978-90-382-1109-1. [NUMOS International Workshop on Numerical Modelling of Thin Film Solar Cells. Gent (BE), 28.03.2007-30.03.2007] R&D Projects: GA MŠk LC510 EU Projects: European Commission(XE) 19670 - ATHLET Institutional research plan: CEZ:AV0Z10100521 Keywords : solar cell * organic * simulation Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Effect of metal nanoparticles interfacial layer on bulk heterojunction PV cell

    Czech Academy of Sciences Publication Activity Database

    Podhájecká, Klára; Pfleger, Jiří

    Strasbourg: European Science Foundation, 2009. P3_80. [E-MRS 2009 Spring Meeting. 08.06.2009-12.06.2009, Strasbourg] R&D Projects: GA AV ČR KAN100500652 Institutional research plan: CEZ:AV0Z40500505 Keywords : metal nanoparticles * bulk heterojunction * photovoltaic cells Subject RIV: CD - Macromolecular Chemistry

  17. 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。

  18. 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%.

  19. Enhanced power conversion efficiency in bulk heterojunction solar cell based on new polyazomethine with vinylene moieties and [6,6]-phenyl C61 butyric acid methyl ester by adding 10-camphorsulfonic acid

    International Nuclear Information System (INIS)

    A polyazomethine (PPV-PAZ-DMB) containing vinylene and aliphatic side chains was synthesized by polycondensation method. The structure of polymer was characterized by means Fourier transform infrared (ATR-FTIR), proton and carbon nuclear magnetic resonance (1H, 13C NMR) spectroscopy and the results show an agreement with the proposed structure. Photovoltaic properties of PPV-PAZ-DMB were studied by constructing bulk heterojunction (BHJ) solar cells with the architecture ITO/PEDOT:PSS/PPV-PAZ-DMB:PCBM/Al, where ITO: indium tin oxide, PEDOT:PSS: poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). Photovoltaic parameters were analyzed taking into account amount of [6,6]-phenyl C61 butyric acid methyl ester (PCBM) added to PPV-PAZ-DMB and presence of 10-camphorsulfonic acid (CSA) in active layer. With the weight ratio PPV-PAZ-DMB:PCBM of 1:3 and the presence of CSA, the power conversion efficiency (PCE) of the device reached 0.32% with open circuit voltage Voc = 0.47 V, short circuit current density Jsc = 2.91 mA/cm2 and fill factor (FF) 0.25 under simulated 100 mW/cm2 AM 1.5 G irradiation. It is showed that the PCE of device with CSA was 40 times higher than that of the device without CSA. Devices were additionally tested by electrochemical impedance spectroscopy. An influence of CSA as a dopant on absorption wavelengths, energy gap and HOMO-LUMO levels was investigated

  20. 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.

  1. 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...

  2. Impact of the Crystalline Packing Structures on Charge Transport and Recombination via Alkyl Chain Tunability of DPP-Based Small Molecules in Bulk Heterojunction Solar Cells.

    Science.gov (United States)

    Song, Chang Eun; Kim, Yu Jin; Suranagi, Sanjaykumar R; Kini, Gururaj P; Park, Sangheon; Lee, Sang Kyu; Shin, Won Suk; Moon, Sang-Jin; Kang, In-Nam; Park, Chan Eon; Lee, Jong-Cheol

    2016-05-25

    A series of small compound materials based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) with three different alkyl side chains were synthesized and used for organic photovoltaics. These small compounds had different alkyl branches (i.e., 2-ethylhexyl (EH), 2-butyloctyl (BO), and 2-hexyldecyl (HD)) attached to DPP units. Thin films made of these compounds were characterized and their solar cell parameters were measured in order to systematically analyze influences of the different side chains of compounds on the film microstructure, molecular packing, and hence, charge-transport and recombination properties. The relatively shorter side chains in the small molecules enabled more ordered packing structures with higher crystallinities, which resulted in higher carrier mobilities and less recombination factors; the small molecule with the EH branches exhibited the best semiconducting properties with a power conversion efficiency of up to 5.54% in solar cell devices. Our study suggested that tuning the alkyl chain length of semiconducting molecules is a powerful strategy for achieving high performance of organic photovoltaics. PMID:27156705

  3. Film morphology effects on the electrical and optical properties of bulk heterojunction organic solar cells based on MEH-PPV/C60 composite

    International Nuclear Information System (INIS)

    The influence of film morphology on the electrical behaviour of an MEH-PPV/C60 organic solar cells has been investigated. The dissociation of photogenerated charge pairs in composites of buckminsterfullerenes (C60) in a conjugated polymer matrix (MEH-PPV) forming dispersed heterojunctions was studied at low C60 acceptor concentrations to separate electron transfer from charge transport effects. The motivation of this study was to analyse the strong dependence of organic solar cell efficiencies on the morphology of the composite. Two effects controlling film morphology have been investigated; the first one being the influence of the fullerene concentration and the second one is the effect of the organic solvent used to deposit the photoactive layer. The sample morphology was studied using atomic force microscopy (AFM). Photoluminescence (PL) experiments and current-voltage (I-V) measurements were performed on the deposited photovoltaic film to investigate the influence of dispersion on the charge transfer process between MEH-PPV and C60. An attempt to explain all the results will be presented

  4. Reel-to-reel wet coating as an efficient up-scaling technique for the production of bulk-heterojunction polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Blankenburg, Lars; Schultheis, Karin; Schache, Hannes; Sensfuss, Steffi; Schroedner, Mario [Thueringisches Institut fuer Textil- und Kunststoff-Forschung e.V., An-Institut der Technischen Universitaet Ilmenau, Breitscheidstrasse 97, D-07407 Rudolstadt (Germany)

    2009-04-15

    In this paper we report for the first time very promising results in up-scaling coating processes for thin flexible polymer solar cell (PSC) application. Two functional layers for PSC devices, the conducting poly- (3,4-ethylene-dioxythiophene):polystyrenesulfonate and the photoactive one (poly-3-hexylthiophene/[6,6]-phenyl-C61-butyric acid methyl ester), could be successfully prepared by continuous reel-to-reel (R2R) wet coating of low-viscosity solutions and dispersions on ITO-coated PET substrates. A laboratory coating machine (LBA-200) was used for R2R slot die coating (1-4 m/min). Out of this R2R-produced bilayer-system PSCs were accomplished and tested. Light power conversion efficiencies up to 1.7% under AM 1.5 illumination (100 mW/cm{sup 2}) could be obtained. (author)

  5. 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.

  6. Electrochromic device and bulk heterojunction solar cell applications of poly 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-dodecyl-2H-benzo[1,2,3]triaz ole (PBEBT)

    Energy Technology Data Exchange (ETDEWEB)

    Balan, Abidin; Baran, Derya; Toppare, Levent [Department of Chemistry, Middle East Technical University, 06531 Ankara (Turkey); Solar Energy Research and Development Center (GUeNAM), Middle East Technical University, 06531 Ankara (Turkey); Sariciftci, Niyazi Serdar [Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University of Linz (Austria)

    2010-10-15

    4,7-Bis(2,3-dihydrothieno [3,4-b] [1,4] dioxin-5-yl)-2-dodecyl-2H-benzo [1,2,3] triazole (BEBT) was polymerized both electrochemically (ePBEBT) and chemically (cPBEBT). Since chemical polymerization enabled a soluble polymer in common organic solvents, a single layer electrochromic device of ePBEBT was constructed. The polymer cPBEBT was also used in bulk heterojunction (BHJ) solar cells as the active layer in combination with a soluble fullerene derivative, 1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C{sub 61} PCBM. (author)

  7. Controlled phase separation for efficient energy conversion in dye/polymer blend bulk heterojunction photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Guo Xiaoyang; Bu Laju; Zhao Yun [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022 (China); Xie Zhiyuan, E-mail: xiezy_n@ciac.jl.c [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022 (China); Geng Yanhou; Wang Lixiang [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022 (China)

    2009-06-30

    Low-cost photovoltaic energy conversion using conjugated polymers has achieved great improvement due to the invention of organic bulk heterojunction, in which the nanoscale phase separation of electron donor and acceptor favors realizing efficient charge separation and collection. We investigated the polymer photovoltaic cells using N, N'-bis(1-ethylpropyl)-3,4,9,10-perylene bis(tetracarboxyl diimide)/poly(3-hexyl thiophene) blend as an active layer. It is found that processing conditions for the blend films have major effects on its morphology and hence the energy conversion efficiency of the resulting devices. By optimizing the processing conditions, the sizes of donor/acceptor phase separation can be adjusted for realizing efficient charge separation and collection. The overall energy conversion efficiency of the photovoltaic cell processed with optimized conditions increases by nearly 40% compared to the normally spin-coated and annealed cell.

  8. 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.

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

    International Nuclear Information System (INIS)

    Bulk heterojunction organic solar cell devices were fabricated using the spray deposited poly [N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′-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:PC61BM active layer based solar cell device under illumination of AM 1.5 G, 100 mW/cm2. Highlights: ► Organic solar cells were fabricated using a spray deposited PCDTBT:PC61BM active layer. ► The active layers deposited with spray conditions show flat morphology. ► Using the selected active layers power conversion efficiency of 1.08% is obtained.

  10. 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.

  11. [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.

  12. 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.

  13. 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%.

  14. Solution-processed tBu4-ZnPc:C61 bulk heterojunction organic photovoltaic cells

    Science.gov (United States)

    Bekalé, Laurent; Barazzouk, Saïd; Sakai, Nobuya; Murakami, Takurou; Miyoshi, Kozo; Miyasaka, Tsutomu; Hotchandani, Surat

    2016-03-01

    A bulk heterojunction (BHJ) organic photovoltaic cell employing tetra-tert-butyl zinc phthalocyanine as electron donor and [6,6]-phenyl C61-buturic acid methyl ester as electron acceptor has been fabricated. The effect of TiOx cathode interlayer, the weight ratio of donor:acceptor in the photoactive layer, and the thermal annealing of photoactive layer on the performance of the cells were investigated. The results show that the insertion of TiOx layer leads to an increase in the photocurrent density of the cells by 11 times compared to those without cathode interlayer. Atomic force microscopy images reveal the formation of well-connected percolated pathways for each phase separated component (donor and acceptor) upon annealing of the film at 150 °C. An important aspect of the present BHJ photovoltaic cell is that it has been obtained by simple wet processes, and most of the fabrication steps have been carried out in ambient air without the use of a glove box.

  15. Performance Improvement of Bulk Heterojunction Organic Photovoltalc Cell by Addition of a Hole Transport Material

    Institute of Scientific and Technical Information of China (English)

    ZHANG Nan; LIU Qian; MAO Jie; LIU Zun-Feng; YANG Li-Ying; YIN Shou-Gen; CHEN Yong-Sheng

    2008-01-01

    @@ A novel photovoltaic cell with an active layer of poly(phenyleneethynylene)(PPE)/C60/N,N'-diphenyl-N,N'-di-(m-tolyl)-p-benzidine(TPD)is designed.In the active layer,PPE is the major component;C60 and TPD are the minor ones.Compared with a control BHJ device based on PPE/C60,the short circuit current density Jsc is increased by 1 order of magnitude,and the whole device performance is increased greatly,however the open circuit voltage Voc is largely decreased.The possible mechanism of the improved performance may be as follows:In the PPE/C60/TPD device,PPE,C60,and TPD serve as the energy harvesting material,the electron transport material,and the hole transport materiall respectively.As the TPD and C60 are spatially separated by PPE,the charge recombination is effectively retarded.

  16. 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.)

  17. 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....

  18. 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

  19. 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.

  20. Organic solar cells: Going green

    Science.gov (United States)

    Luo, Guoping; Wu, Hongbin

    2016-02-01

    High-performance polymer solar cells are normally processed with halogenated solvents, which are toxic and hazardous. Now, high power-conversion efficiency in bulk-heterojunction devices is achieved by using a non-toxic hydrocarbon solvent through an environmentally friendly processing route.

  1. 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.

  2. 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...

  3. 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.

  4. 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

  5. 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...

  6. 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

  7. 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)

  8. 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.

  9. Organic hybrid planar-nanocrystalline bulk heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Forrest, Stephen R.; Yang, Fan

    2013-04-09

    A photosensitive optoelectronic device having an improved hybrid planar bulk heterojunction includes a plurality of photoconductive materials disposed between the anode and the cathode. The photoconductive materials include a first continuous layer of donor material and a second continuous layer of acceptor material. A first network of donor material or materials extends from the first continuous layer toward the second continuous layer, providing continuous pathways for conduction of holes to the first continuous layer. A second network of acceptor material or materials extends from the second continuous layer toward the first continuous layer, providing continuous pathways for conduction of electrons to the second continuous layer. The first network and the second network are interlaced with each other. At least one other photoconductive material is interspersed between the interlaced networks. This other photoconductive material or materials has an absorption spectra different from the donor and acceptor materials.

  10. 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)

  11. 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

  12. 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...

  13. Thermocleavable Materials for Polymer Solar Cells with High Open Circuit Voltage-A Comparative Study

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Gevorgyan, Suren; Jørgensen, Mikkel;

    2009-01-01

    The search for polymer solar cells giving a high open circuit voltage was conducted through a comparative study of four types of bulk-heterojunction solar cells employing different photoactive layers. As electron donors the thermo-cleavable polymer poly-(3-(2-methylhexyloxycarbonyl)dithiophene) (P3...

  14. 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 ...

  15. 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)

  16. Understanding the morphology of solution processed fullerene-free small molecule bulk heterojunction blends.

    Science.gov (United States)

    Namepetra, Andrew; Kitching, Elizabeth; Eftaiha, Ala'a F; Hill, Ian G; Welch, Gregory C

    2016-05-14

    Bulk-heterojunction (BHJ) molecular blends prepared from small molecules based on diketopyrrolopyrrole (DPP) and perylene-diimide (PDI) chromophores have been studied using optical absorption, cyclic voltammetry, photoluminescence quenching, X-ray diffraction, atomic force microscopy, and current-voltage measurements. The results provided useful insights into the use of DPP and PDI based molecules as donor-acceptor composites for organic photovoltaic (OPV) applications. Beside optoelectronic compatibility, the choice of active layer processing conditions is of key importance to improve the performance of BHJ solar cells. In this context, post-production treatments, viz. thermal and solvent vapour annealing, and the use of 1,8-diiodooctane as a solvent additive were employed to optimize the morphology of blend films. X-ray diffraction and atomic force microscopy indicated that the aforementioned processing strategies led to non-optimal composite morphologies with significantly large crystallites in comparison to exciton diffusion lengths. Although the open circuit voltage of the OPV devices was satisfactory (0.78 V), it was anticipated that the bulky domains hamper charge dissociation and transport, which resulted in low photovoltaic performance. PMID:27087259

  17. 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.

  18. 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.

  19. 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...

  20. 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

  1. Self-Organized One-Dimensional TiO2 Nano tube/Nano wire Array Films for Use in Excitonic Solar Cells

    International Nuclear Information System (INIS)

    We review the use of self-assembled, vertically oriented one-dimensional (1 D) titania nano wire and nano tube geometries in several third-generation excitonic solar cell designs including those based upon bulk heterojunction, ordered heterojunction, Forester resonance energy transfer (FRET), and liquid-junction dye-sensitized solar cells (DSSCs)

  2. Self-Organized One-Dimensional TiO2 Nanotube/Nanowire Array Films for Use in Excitonic Solar Cells: A Review

    OpenAIRE

    Ningzhong Bao; Xinjian Feng; Grimes, Craig A.

    2012-01-01

    We review the use of self-assembled, vertically oriented one-dimensional (1D) titania nanowire and nanotube geometries in several third-generation excitonic solar cell designs including those based upon bulk heterojunction, ordered heterojunction, Förster resonance energy transfer (FRET), and liquid-junction dye-sensitized solar cells (DSSCs).

  3. Organic solar cells fundamentals, devices, and upscaling

    CERN Document Server

    Rand, Barry P

    2014-01-01

    Solution-Processed DonorsB. Burkhart, B. C. ThompsonSmall-Molecule and Vapor-Deposited Organic Photovoltaics R. R. Lunt, R. J. HolmesAcceptor Materials for Solution-Processed Solar Cells Y. HeInterfacial Layers R. Po, C. Carbonera, A. BernardiElectrodes in Organic Photovoltaic Cells S. Yoo, J.-Y. Lee, H. Kim, J. LeeTandem and Multi-Junction Organic Solar Cells J. Gilot, R. A. J. JanssenBulk Heterojunction Morphology Control and Characterization T. Wang, D. G. LidzeyOptical Modeling and Light Management

  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. 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

  6. 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...

  7. 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...

  8. 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...

  9. Auger electron nanoscale mapping and x-ray photoelectron spectroscopy combined with gas cluster ion beam sputtering to study an organic bulk heterojunction

    International Nuclear Information System (INIS)

    The lateral and vertical distributions of organic p/n bulk heterojunctions for an organic solar cell device are, respectively, investigated using nanometer-scale Auger electron mapping and using X-ray photoelectron spectroscopy (XPS) with Ar gas cluster ion beam (GCIB) sputtering. The concentration of sulfur, present only in the p-type material, is traced to verify the distribution of p-type (donor) and n-type (acceptor) materials in the blended structure. In the vertical direction, a considerable change in atomic sulfur concentration is observed using XPS depth profiling with Ar GCIB sputtering. In addition, Auger electron mapping of sulfur reveals the lateral 2-dimensional distribution of p- and n-type materials. The combination of Auger electron mapping with Ar GCIB sputtering should thereby allow the construction of 3-dimensional distributions of p- and n-type materials in organic photovoltaic cells

  10. 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.

  11. Persistent photovoltage in methylammonium lead iodide perovskite solar cells

    OpenAIRE

    Baumann, A.; Tvingstedt, K.; Heiber, M. C.; Väth, S.; C. Momblona; H. J. Bolink; Dyakonov, V.

    2014-01-01

    We herein perform open circuit voltage decay (OCVD) measurements on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to increase the understanding of the charge carrier recombination dynamics in this emerging technology. Optically pulsed OCVD measurements are conducted on CH3NH3PbI3 solar cells and compared to results from another type of thin-film photovoltaics, namely, the two reference polymer–fullerene bulk heterojunction solar cell devices based on P3HT:PC60BM and PTB7:PC70...

  12. High Efficiency Polymer Solar Cells with Long Operating Lifetimes

    KAUST Repository

    Peters, Craig H.

    2011-04-20

    Organic bulk-heterojunction solar cells comprising poly[N-9\\'-hepta-decanyl- 2,7-carbazole-alt-5,5-(4\\',7\\'-di-2-thienyl-2\\', 1\\',3\\'-benzothiadiazole) (PCDTBT) are systematically aged and demonstrate lifetimes approaching seven years, which is the longest reported lifetime for polymer solar cells. An experimental set-up is described that is capable of testing large numbers of solar cells, holding each device at its maximum power point while controlling and monitoring the temperature and light intensity. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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).

  14. 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

  15. 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. ...

  16. Adhesion in flexible organic and hybrid organic/inorganic light emitting device and solar cells

    International Nuclear Information System (INIS)

    This paper presents the results of an experimental study of the adhesion between bi-material pairs that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, organic bulk heterojunction solar cells, and hybrid organic/inorganic solar cells on flexible substrates. Adhesion between the possible bi-material pairs is measured using force microscopy (AFM) techniques. These include: interfaces that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, bulk heterojunction solar cells, and hybrid combinations of titanium dioxide (TiO2) and poly(3-hexylthiophene). The results of AFM measurements are incorporated into the Derjaguin-Muller-Toporov model for the determination of adhesion energies. The implications of the results are then discussed for the design of robust organic and hybrid organic/inorganic electronic devices

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

    International Nuclear Information System (INIS)

    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

  18. 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.

  19. Electrospun Polymer-Fiber Solar Cell

    Directory of Open Access Journals (Sweden)

    Shinobu Nagata

    2013-01-01

    Full Text Available A novel electrospun polymer-fiber solar cell was synthesized by electrospinning a 1 : 2.5 weight% ratio mixture of poly[2-methoxy-5-(2-ethylhexyloxy-1,4-phenylenevinylene] (MEH-PPV and [6,6]-phenyl C61 butyric acid methyl ester (PCBM resulting in bulk heterojunctions. Electrospinning is introduced as a technique that may increase polymer solar cell efficiency, and a list of advantages of the technique applied to solar cells is discussed. The device achieved a power conversion efficiency of %. The absorption and photoluminescence of MEH-PPV nanofibers are compared to thin films of the same material. Electrospun nanofibers are discussed as a favorable structure for application in polymer solar cells.

  20. Inverted heterojunction solar cells incorporating fullerene/polythiophene composite core/shell nanorod arrays

    International Nuclear Information System (INIS)

    We have fabricated inverted heterojunction solar cell devices incorporating [6,6]-phenyl-C61-butyric acid methyl ester/poly(3-hexylthiophene) core/shell nanorod arrays by using an anodic alumina oxide template. The internal quantum efficiencies and external quantum efficiencies of these core/shell nanorod inverted solar cells were higher than those of the corresponding conventional inverted bulk heterojunction device. The optimized nanorod array structure had a high hole mobility that was over one order magnitude greater than that of the conventional bulk heterojunction structure, as determined by fitting the dark J-V curves into the space charge limited current model. The more efficient carrier transport of the device incorporating the core/shell nanorod arrays provided it with both a higher short-circuit current density and power conversion efficiency.

  1. 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.

  2. Sample preparation for scanning Kelvin probe microscopy studies on cross sections of organic solar cells

    OpenAIRE

    Michael Scherer; Rebecca Saive; Dominik Daume; Michael Kröger; Wolfgang Kowalsky

    2013-01-01

    We prepared cross sections of P3HT:PCBM bulk heterojunction (BHJ) organic solar cells (OSCs) for the characterization of their potential distribution with scanning Kelvin probe microscopy. We compared results of samples obtained by microtome cutting of OSCs on plastic substrates, cleaving of OSCs on glass substrates, and milling with a focused ion beam. Their potential distributions were in good agreement with each other. Under short circuit conditions, potential gradients were detected in vi...

  3. Photoinduced Charge Transport in a BHJ Solar Cell Controlled by an External Electric Field

    OpenAIRE

    Yongqing Li; Yanting Feng; Mengtao Sun

    2015-01-01

    This study investigated theoretical photoinduced charge transport in a bulk heterojunction (BHJ) solar cell controlled by an external electric field. Our method for visualizing charge difference density identified the excited state properties of photoinduced charge transfer, and the charge transfer excited states were distinguished from local excited states during electronic transitions. Furthermore, the calculated rates for the charge transfer revealed that the charge transfer was strongly i...

  4. Observation of the subgap optical absorption in polymer-fullerene blend solar cells

    Czech Academy of Sciences Publication Activity Database

    Goris, L.; Poruba, Aleš; Hoďáková, Lenka; Vaněček, Milan; Haenen, K.; Nesladek, M.; Wagner, P.; Vanderzande, D.; De Schepper, L.; Manca, J.V.

    2006-01-01

    Roč. 88, č. 5 (2006), 052113/1-052113/3. ISSN 0003-6951 Grant ostatní: BIL Cooperation Flanders-Czech Republic(BE) BOF04B03 Institutional research plan: CEZ:AV0Z10100521 Keywords : solar cells * optical spectroscopy * polymer- fulleren e bulk heterojunctions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.977, year: 2006

  5. Photovoltaic properties and morphology of organic solar cells based on liquid-crystal semiconducting polymer with additive

    International Nuclear Information System (INIS)

    Bulk heterojunction organic solar cell based on liquid crystal semiconducting polymers of poly[9,9-dioctylfluorene-co-bithiophene] (F8T2) as p-type semiconductors and fullerenes (C60) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron donor and acceptor has been fabricated and characterized for improving photovoltaic and optical properties. The photovoltaic performance including current voltage curves in the dark and illumination of the F8T2/C60 conventional and inverted bulk heterojunction solar cells were investigated. Relationship between the photovoltaic properties and morphological behavior was focused on tuning for optimization of photo-voltaic performance under annealing condition near glass transition temperature. Additive-effect of diiodooctane (DIO) and poly(3-hexylthiophene-2,5-diyl) (P3HT) on the photovoltaic performance and optical properties was investigated. Mechanism of the photovoltaic properties of the conventional and inverted solar cells will be discussed by the experimental results

  6. Innovative approaches to improve bulk heterojunction organic photovoltaic device performance

    Science.gov (United States)

    Zhang, Ye

    In this thesis we studied the electrical properties of bulk heterojunction organic photovoltaic (OPV) devices fabricated using a variety of conjugated polymers, including regioregular P3HT, regiorandom P3HT, MEH-PPV and Mercedes, and several fullerene derivatives including [C61]PCBM, [C71]PCBM, bis-PCBM, Jalapeno and Habanero. We first optimized the fabrication recipe for P3HT/PCBM devices to yield a power conversion efficiency ˜3.5%, which is comparable to the reported state-of-the-art P3HT/PCBM device performance. We then fabricated OPV devices using alternative high LUMO fullerenes and a narrow bandgap/deep HOMO polymer to enhance OPV device performance and studied the electrical properties of these devices. Devices fabricated using P3HT/Jalapeno demonstrate a high efficiency ˜5%. Finally, we discovered an innovative spin-related method, which can potentially compliment the use of alternative donor/acceptor materials, to enhance OPV device performance. We doped the spin ½ radial Galvinoxyl into P3HT/PCBM devices and improved efficiency from 3.5% to 4%. Our experimental results suggest that the existence of Galvinoxyl at the P3HT/PCBM interface facilitates the exciton/polaron dissociation process, while Galvinoxyl molecules that are sparsely distributed in PCBM domains yield enhanced free charge carrier transport.

  7. 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.

  8. Substituted perylene diimides as electron acceptors in organic solar cells: Suppressing aggregate formation to increase device efficiency

    International Nuclear Information System (INIS)

    Perylene diimide (PDI) is a promising electron acceptor material for high open circuit voltage bulk heterojunction organic solar cells. However, many PDI molecules have the drawback of strong aggregation leading to intermolecular excited state formation that results in exciton trapping. These traps can effectively limit the diffusion of excitons to the interface where charge separation occurs and thus strongly reduce the charge generation efficiency. In this contribution we study the influence of substitution of PDI molecules with side groups attached to the terminal and to the perylene core positions on the formation of aggregates. In particular transient photoluminescence and absorption spectroscopy are used to probe the impact of aggregation on the dynamics of charge generation and recombination in bulk heterojunction solar cells. Besides, AFM, x-ray and solid state NMR techniques are used to get further insight into the solid state morphology of polymer: PDI blends on different length scales. Finally, we correlate the photophysical properties of the PDI derivatives with the efficiency of bulk heterojunction organic solar cells and present unprecedented efficiencies from polymer: PDI solar cells.

  9. Small-bandgap polymer solar cells with unprecedented short-circuit current density and high fill factor.

    Science.gov (United States)

    Choi, Hyosung; Ko, Seo-Jin; Kim, Taehyo; Morin, Pierre-Olivier; Walker, Bright; Lee, Byoung Hoon; Leclerc, Mario; Kim, Jin Young; Heeger, Alan J

    2015-06-01

    Small-bandgap polymer solar cells (PSCs) with a thick bulk heterojunction film of 340 nm exhibit high power conversion efficiencies of 9.40% resulting from high short-circuit current density (JSC ) of 20.07 mA cm(-2) and fill factor of 0.70. This remarkable efficiency is attributed to maximized light absorption by the thick active layer and minimized recombination by the optimized lateral and vertical morphology through the processing additive. PMID:25899940

  10. A Bicontinuous Double Gyroid Hybrid Solar Cell

    KAUST Repository

    Crossland, Edward J. W.

    2009-08-12

    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 block copolymer film. The highly ordered pore structure is ideal for uniform infiltration of an organic hole transporting material, and solid-state dye-sensitized solar cells only 400 nm thick exhibit up to 1.7% power conversion efficiency. This patterning technique can be readily extended to other promising heterojunction systems and is a major step toward realizing the full potential of self-assembly in the next generation of device technologies. © 2009 American Chemical Society.

  11. 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.

  12. Poly(3-hexylthiophene) - CdSe quantum dot bulk heterojunction solar cells: Influence of the functional end-group of the polymer

    KAUST Repository

    Palaniappan, Kumaranand

    2009-06-23

    The synthesis of H/thiol terminated P3HT from Br/allyl-terminated P3HT precursor was analyzed. The photovoltaic response of blends were prepared of H/thiol terminated P3HT with spherical CdSe quantum dots(QD) and compares the results with regioregular H/Br and Br/aryl-terminated P3HT. Phase segregation was carried by mixing relatively polar pyridine treated CdSe QD with nonpolar P3HT. The experiment revealed that a high loading of CdSe is necessary for an efficient charge transport and different loading ratios of CdSe has been investigated to correlate the photovoltaic response as a function of ration between donor H/thiol-P3ht polymer and acceptor Cdse QD. The results show that H/Br-P3HT, H/thiol- and Br/allyl-terminated P3HT exhibits better performance and Cdse quantum dots were used to obtain results.

  13. Fabrication and study of organic solar cells composed of P3HT/PCBM blend with monolayers of P(VDF-TrFE)

    Science.gov (United States)

    Carrasco, Hector; Vedrine, Josee; Luis Rosa Collaboration

    2014-03-01

    Organic polymeric materials that are conducting provide an added facility in device fabrication, particularly in solar cell applications. In this work, we study the electrical and morphological properties of bulk hetero-junction solar cells fabricated with poly (3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric-acid-methyl ester (PCBM) blends, when a monolayer of the ferroelectric polymer poly[(vinylidenefluoride-co-trifluoroethylene] [P(VDF-TrFE)] is deposited between ITO conductor and bulk heterojunction. The bulk heterojunction and ferroelectric films are annealed at 140 °C under vacuum atmosphere to improve their crystallinity, which may assist in enhanced charge transfer. We measure device photovoltaic properties with changing blend thickness, while keeping the ferroelectric layer constant.. The current-voltage characteristics are measured and compared for the different film thicknesses. AFM techniques are used to analyze their morphological and conductive properties.

  14. Incorporation of Furan into Low Band-Gap Polymers for Efficient Solar Cells

    KAUST Repository

    Woo, Claire H.

    2010-11-10

    The design, synthesis, and characterization of the first examples of furan-containing low band-gap polymers, PDPP2FT and PDPP3F, with substantial power conversion efficiencies in organic solar cells are reported. Inserting furan moieties in the backbone of the conjugated polymers enables the use of relatively small solubilizing side chains because of the significant contribution of the furan rings to overall polymer solubility in common organic solvents. Bulk heterojunction solar cells fabricated from furan-containing polymers and PC71BM as the acceptor showed power conversion efficiencies reaching 5.0%. © 2010 American Chemical Society.

  15. Cross Kelvin force microscopy and conductive atomic force microscopy studies of organic bulk heterojunction blends for local morphology and electrical behavior analysis

    Energy Technology Data Exchange (ETDEWEB)

    Villeneuve-Faure, C., E-mail: Christina.villeneuve@laplace.unvi-tlse.fr [LAPLACE, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse (France); UPS, INPT, Université de Toulouse, LCC 31077 Toulouse (France); Le Borgne, D. [LAPLACE, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse (France); UPS, INPT, Université de Toulouse, LCC 31077 Toulouse (France); LCC-CNRS, 205 route de Narbonne, F-31077 Toulouse Cedex 4 (France); Bedel-Pereira, E.; Séguy, I. [UPS, INPT, Université de Toulouse, LCC 31077 Toulouse (France); LAAS-CNRS, 7 Avenue du Colonel Roche, 31077 Toulouse Cedex 4 (France); Moineau Chane-Ching, K. I.; Hernandez-Maldonado, D. [UPS, INPT, Université de Toulouse, LCC 31077 Toulouse (France); LCC-CNRS, 205 route de Narbonne, F-31077 Toulouse Cedex 4 (France)

    2015-02-07

    Bulk Heterojunction (BHJ) organic photovoltaic devices performances depend on the relative organization and physical properties of the electron-donor and -acceptor materials. In this paper, BHJs of poly(3-hexyl-thiophene) (P3HT) associated with an electron acceptor material, 1-(3-methoxycarbonyl)-propyl-1-phenyl[6,6]C6 (PCBM) or [Ni(4dodpedt){sub 2}], are studied in terms of morphology, ordering, and electrical properties. First, comparison between the two BHJs performed by Atomic Force Microscopy (AFM) and Raman characterizations shows that P3HT structuration is improved by blending with [Ni(4dodpedt){sub 2}]. Then, the relationship between charges trapping, electrical properties, and film morphology is investigated using conductive AFM and Kelvin Force Microscopy. Measurements in dark condition and under solar cell simulator provide complementary information on electrical phenomena in these organic nanostructures. Finally, time dependent measurement highlights the influence of charges stacking on conduction. Specifically, we demonstrate that charge accumulation initiated by illumination remains valid after switching off the light, and induces the modification in current versus voltage characteristic of P3HT: PCBM blend. Finally, we observe a current increasing which can be attributed to the energy barrier decreasing due to charges trapping in PCBM.

  16. Achieving High Performance Perovskite Solar Cells

    Science.gov (United States)

    Yang, Yang

    2015-03-01

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

  17. 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

  18. 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.

  19. Deep absorbing porphyrin small molecule for high-performance organic solar cells with very low energy losses.

    Science.gov (United States)

    Gao, Ke; Li, Lisheng; Lai, Tianqi; Xiao, Liangang; Huang, Yuan; Huang, Fei; Peng, Junbiao; Cao, Yong; Liu, Feng; Russell, Thomas P; Janssen, René A J; Peng, Xiaobin

    2015-06-17

    We designed and synthesized the DPPEZnP-TEH molecule, with a porphyrin ring linked to two diketopyrrolopyrrole units by ethynylene bridges. The resulting material exhibits a very low energy band gap of 1.37 eV and a broad light absorption to 907 nm. An open-circuit voltage of 0.78 V was obtained in bulk heterojunction (BHJ) organic solar cells, showing a low energy loss of only 0.59 eV, which is the first report that small molecule solar cells show energy losses X-ray diffraction, resonant soft X-ray scattering, and transmission electron microscopy under different fabrication conditions. PMID:26035342

  20. 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.

  1. Theoretical and experimental investigations of the 2-(4-chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile molecule as a potential acceptor in organic solar cells.

    Science.gov (United States)

    Kazici, Mehmet; Bozar, Sinem; Yuksel, Sureyya Aydin; Ongul, Fatih; Gokce, Halil; Gunes, Serap; Goreci, Cigdem Yorur

    2016-06-10

    A novel soluble asymmetric acrylonitrile derivative, 2-(4-Chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile (CPCPFA, 3) was synthesized in three steps by Knoevenagel condensation. The structure of the CPCPFA was characterized using UV-vis, FTIR, (1)H NMR, (13)C NMR, and LC-MS. CPCPFA was evaluated as an electron acceptor in bulk heterojunction organic solar cells. Its optical and electronic properties as well as photovoltaic performance were investigated. PMID:27145976

  2. Theoretical and experimental investigations of the 2-(4-chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile molecule as a potential acceptor in organic solar cells

    Science.gov (United States)

    Kazici, Mehmet; Bozar, Sinem; Aydin Yuksel, Sureyya; Ongul, Fatih; Gokce, Halil; Gunes, Serap; Yorur Goreci, Cigdem

    2016-06-01

    A novel soluble asymmetric acrylonitrile derivative, 2-(4-Chlorophenyl)-3-{[5-(2-cyano-2-phenylethenyl)]furan-2-yl}acrylonitrile (CPCPFA, 3) was synthesized in three steps by Knoevenagel condensation. The structure of the CPCPFA was characterized using UV–vis, FTIR, 1H NMR, 13C NMR, and LC-MS. CPCPFA was evaluated as an electron acceptor in bulk heterojunction organic solar cells. Its optical and electronic properties as well as photovoltaic performance were investigated.

  3. Oligo and Poly-thiophene/Zno Hybrid Nanowire Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Briseno, Alejandro L.; Holcombe, Thomas W.; Boukai, Akram I.; Garnett, Erik C.; Shelton, Steve W.; Frechet, Jean J. M.; Yang, Peidong

    2009-11-03

    We demonstrate the basic operation of an organic/inorganic hybrid single nanowire solar cell. End-functionalized oligo- and polythiophenes were grafted onto ZnO nanowires to produce p-n heterojunction nanowires. The hybrid nanostructures were characterized via absorption and electron microscopy to determine the optoelectronic properties and to probe the morphology at the organic/inorganic interface. Individual nanowire solar cell devices exhibited well-resolved characteristics with efficiencies as high as 0.036percent, Jsc = 0.32 mA/cm2, Voc = 0.4 V, and a FF = 0.28 under AM 1.5 illumination with 100 mW/cm2 light intensity. These individual test structures will enable detailed analysis to be carried out in areas that have been difficult to study in bulk heterojunction devices.

  4. Interface engineering for efficient fullerene-free organic solar cells

    International Nuclear Information System (INIS)

    We demonstrate the role of zinc oxide (ZnO) morphology and addition of an acceptor interlayer to achieve high efficiency fullerene-free bulk heterojunction inverted organic solar cells. Nanopatterning of the ZnO buffer layer enhances the effective light absorption in the active layer, and the insertion of a twisted perylene acceptor layer planarizes and decreases the electron extraction barrier. Along with an increase in current homogeneity, the reduced work function difference and selective transport of electrons prevent the accumulation of charges and decrease the electron-hole recombination at the interface. These factors enable an overall increase of efficiency to 4.6%, which is significant for a fullerene-free solution-processed organic solar cell

  5. Interface engineering for efficient fullerene-free organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shivanna, Ravichandran; Narayan, K. S., E-mail: rajaram@jncasr.ac.in, E-mail: narayan@jncasr.ac.in [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Rajaram, Sridhar, E-mail: rajaram@jncasr.ac.in, E-mail: narayan@jncasr.ac.in [International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2015-03-23

    We demonstrate the role of zinc oxide (ZnO) morphology and addition of an acceptor interlayer to achieve high efficiency fullerene-free bulk heterojunction inverted organic solar cells. Nanopatterning of the ZnO buffer layer enhances the effective light absorption in the active layer, and the insertion of a twisted perylene acceptor layer planarizes and decreases the electron extraction barrier. Along with an increase in current homogeneity, the reduced work function difference and selective transport of electrons prevent the accumulation of charges and decrease the electron-hole recombination at the interface. These factors enable an overall increase of efficiency to 4.6%, which is significant for a fullerene-free solution-processed organic solar cell.

  6. The inverse correlation between series resistance and parallel resistance of small molecule organic solar cells

    Institute of Scientific and Technical Information of China (English)

    Kewei Wang; Yufeng Zheng; Gu Xu; Xiuping Xu

    2015-01-01

    Understanding the inversely correlated series resistance (Rs) and parallel resistance (Rp) remains a challenge. Here we report that the variation of Rs and Rp is inversely related through the morphology of the donor and acceptor interface in CuPc organic solar cells, when comparing the bilayer structure and bulk heterojunction structure. It was also found that the charge carrier concentration near the donor–acceptor interface plays an important role in the relationships of Rs and Rp under fixed interfacial morphology, which was verified by the change of Voc. The inversely correlated Rs and Rp contributes to the improvement of the fill factor, and in turn the power conversion efficiency.

  7. Sample preparation for scanning Kelvin probe microscopy studies on cross sections of organic solar cells

    Directory of Open Access Journals (Sweden)

    Michael Scherer

    2013-09-01

    Full Text Available We prepared cross sections of P3HT:PCBM bulk heterojunction (BHJ organic solar cells (OSCs for the characterization of their potential distribution with scanning Kelvin probe microscopy. We compared results of samples obtained by microtome cutting of OSCs on plastic substrates, cleaving of OSCs on glass substrates, and milling with a focused ion beam. Their potential distributions were in good agreement with each other. Under short circuit conditions, potential gradients were detected in vicinity of the electrode/organics interfaces, with negligible electric fields within the bulk. We contacted the OSCs in a defined manner and studied their potential distribution under operating conditions.

  8. Charge Formation, Recombination, and Sweep-Out Dynamics in Organic Solar Cells

    OpenAIRE

    Cowan, Sarah R.; Banerji, Natalie; Leong, Wei Lin; Heeger, Alan J.

    2012-01-01

    This article presents a critical discussion of the various physical processes occurring in organic bulk heterojunction (BHJ) solar cells based on recent experimental results. The investigations span from photoexcitation to charge separation, recombination, and sweep-out to the electrodes. Exciton formation and relaxation in poly[N-9?-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole) (PCDTBT) and poly-3(hexylthiophene) (P3HT) are discussed based on a fluorescen...

  9. PCDTBT based solar cells: one year of operation under real-world conditions

    Science.gov (United States)

    Zhang, Yiwei; Bovill, Edward; Kingsley, James; Buckley, Alastair R.; Yi, Hunan; Iraqi, Ahmed; Wang, Tao; Lidzey, David G.

    2016-02-01

    We present measurements of the outdoor stability of PCDTBT:PC71BM based bulk heterojunction organic solar cells for over the course of a year. We find that the devices undergo a burn-in process lasting 450 hours followed by a TS80 lifetime of up to 6200 hours. We conclude that in the most stable devices, the observed TS80 lifetime is limited by thermally-induced stress between the device layers, as well as materials degradation as a result of edge-ingress of water or moisture through the encapsulation.

  10. Geometric light trapping with a V-trap for efficient organic solar cells

    KAUST Repository

    Kim, Soo Jin

    2013-03-14

    The efficiency of today’s most efficient organic solar cells is primarily limited by the ability of the active layer to absorb all the sunlight. While internal quantum efficiencies exceeding 90% are common, the external quantum efficiency rarely exceeds 70%. Light trapping techniques that increase the ability of a given active layer to absorb light are common in inorganic solar cells but have only been applied to organic solar cells with limited success. Here, we analyze the light trapping mechanism for a cell with a V-shape substrate configuration and demonstrate significantly improved photon absorption in an 5.3%-efficient PCDTBT:PC70BM bulk heterojunction polymer solar cell. The measured short circuit current density improves by 29%, in agreement with model predictions, and the power conversion efficiency increases to 7.2%, a 35% improvement over the performance in the absence of a light trap.

  11. 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

    The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Under illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P+, and negative, P-, polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of 1H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40 - 60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR. Strong

  12. Flow-enhanced solution printing of all-polymer solar cells

    Science.gov (United States)

    Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A.; Gu, Kevin; Gu, Xiaodan; Tee, Benjamin C. K.; Pang, Changhyun; Yan, Hongping; Zhao, Dahui; Toney, Michael F.; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2015-08-01

    Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a ~90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. We expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility.

  13. Exploring Spray-Coating Techniques for Organic Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Wanyi Nie

    2012-01-01

    Full Text Available We have investigated spray coating as a novel processing method for organic solar cell fabrication. In this work, spraying parameters and organic solvent influences have been correlated with cell performance. Using airbrush fabrication, bulk heterojunction photovoltaic devices based on a new low band gap donor material: poly[(4,8-bis(1-pentylhexyloxybenzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-2,1,3-benzoxadiazole-4,7-diyl] with the C60-derivative (6,6-phenyl C61-butyric acid methyl ester (PCBM as an acceptor, have achieved power conversion efficiencies over 3%. We show that airbrush fabrication can be carried out with simple solvents such as pristine 1,2-dichlorobenzene. Moreover, the influence of device active area has been studied and the 1 cm2 device by spray coating maintained an excellent power conversion efficiency of 3.02% on average.

  14. Molecular and Nanoscale Engineering of High Efficiency Excitonic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jenekhe, Samson A. [Univ. of Washington, Seattle, WA (United States); Ginger, David S. [Univ. of Washington, Seattle, WA (United States); Cao, Guozhong [Univ. of Washington, Seattle, WA (United States)

    2016-01-15

    We combined the synthesis of new polymers and organic-inorganic hybrid materials with new experimental characterization tools to investigate bulk heterojunction (BHJ) polymer solar cells and hybrid organic-inorganic solar cells during the 2007-2010 period (phase I) of this project. We showed that the bulk morphology of polymer/fullerene blend solar cells could be controlled by using either self-assembled polymer semiconductor nanowires or diblock poly(3-alkylthiophenes) as the light-absorbing and hole transport component. We developed new characterization tools in-house, including photoinduced absorption (PIA) spectroscopy, time-resolved electrostatic force microscopy (TR-EFM) and conductive and photoconductive atomic force microscopy (c-AFM and pc-AFM), and used them to investigate charge transfer and recombination dynamics in polymer/fullerene BHJ solar cells, hybrid polymer-nanocrystal (PbSe) devices, and dye-sensitized solar cells (DSSCs); we thus showed in detail how the bulk photovoltaic properties are connected to the nanoscale structure of the BHJ polymer solar cells. We created various oxide semiconductor (ZnO, TiO2) nanostructures by solution processing routes, including hierarchical aggregates and nanorods/nanotubes, and showed that the nanostructured photoanodes resulted in substantially enhanced light-harvesting and charge transport, leading to enhanced power conversion efficiency of dye-sensitized solar cells.

  15. Water-Induced Degradation of Polymer Solar Cells Studied by (H2O)-O-18 Labeling

    DEFF Research Database (Denmark)

    Norrman, Kion; Gevorgyan, Suren; Krebs, Frederik C

    2009-01-01

    Water-induced degradation of polymer photovoltaics based on the active materials poly(3-hexylthiophene) (P3HT) or poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) was studied. The solar cell devices comprised a bulk heterojunction formed by the active material and [6,6]-phenyl-C......61-butyric acid methyl ester (PCBM) in a standard device geometry. The use of H218O in conjunction with time-of-flight secondary ion mass spectrometry enabled mapping of the parts of the device that were induced by water. A comparison was made between the two active materials and between devices that...

  16. Possibility to Use Low Temperature Pulsed RF Sputtered Indium Tin Oxide for the Fabrication of Organic Solar Cell

    OpenAIRE

    Partha Pratim Ray; Animesh Layek; Somnath Middya

    2013-01-01

    In this work we have used pulsed RF sputtering method to deposit indium tin oxide (ITO) for the fabrication of P3HT:PCBM based bulk heterojunction polymer solar cell. We have deposited ITO at low substrate temperature (100°C) and for different pulse modes. Oxygen was used as an admixture to the sputtering gas argon, and the percentage was varied from 0 to 6%. During deposition, plasma was studied by optical emission spectroscopy (OES) method. For our present range of deposition conditions low...

  17. Electrodeposited cobalt sulfide hole collecting layer for polymer solar cells

    International Nuclear Information System (INIS)

    In polymer solar cells based on the blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester, the hole collecting layer has to be endowed with its ionization potential close to or greater than that of P3HT (∼5 eV). Conductive polymer blends such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and metal oxides such as vanadium pentoxide (V2O5) and molybdenum trioxide (MoO3) satisfy this requirement and have been the most common materials used so far in bulk heterojunction structures. We report here cobalt sulfide (CoS) to be a promising hole collecting material deposited by convenient and room temperature electrodeposition. By simply tuning the CoS electrodeposition parameters, power conversion efficiencies similar (within 15%) to a reference structure with PEDOT:PSS were obtained

  18. Charge generation and recombination in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Meister, Michael; Wonneberger, Henrike; Li, Chen; Muellen, Klaus; Laquai, Frederic [Max-Planck-Institute for Polymer Research, Mainz (Germany)

    2010-07-01

    Charge recombination is one of the efficiency limiting processes in bulk heterojunction and dye-sensitized organic solar cells. To determine the presence of charges and the dynamics of charge generation and recombination photoinduced absorption spectroscopy (PIA) and transient absorption spectroscopy (TAS) are particularly useful techniques, since most of the investigated states are non-emissive. These methods allow to investigate all important mechanisms that lead to photocurrent generation beginning with the excitation of the dye, followed by charge transfer to a metal oxide semiconductor and regeneration of the dye by an electrolyte or an organic solid state hole conductor. In this study, we present spectroscopic experiments on dye-doped titanium dioxide films using novel all-organic perylene monoimide dyes as sensitizer with and without solid state hole conductor and on real device structures. We correlate the observed charge generation and recombination dynamics with the device efficiency to understand the relation between dye-structure, photophysics and device performance.

  19. Persistent photovoltage in methylammonium lead iodide perovskite solar cells

    Directory of Open Access Journals (Sweden)

    A. Baumann

    2014-08-01

    Full Text Available We herein perform open circuit voltage decay (OCVD measurements on methylammonium lead iodide (CH3NH3PbI3 perovskite solar cells to increase the understanding of the charge carrier recombination dynamics in this emerging technology. Optically pulsed OCVD measurements are conducted on CH3NH3PbI3 solar cells and compared to results from another type of thin-film photovoltaics, namely, the two reference polymer–fullerene bulk heterojunction solar cell devices based on P3HT:PC60BM and PTB7:PC70BM blends. We observe two very different time domains of the voltage transient in the perovskite solar cell with a first drop on a short time scale that is similar to the decay in the studied organic solar cells. However, 65%–70% of the maximum photovoltage persists on much longer timescales in the perovskite solar cell than in the organic devices. In addition, we find that the recombination dynamics in all time regimes are dependent on the starting illumination intensity, which is also not observed in the organic devices. We then discuss the potential origins of these unique behaviors.

  20. Model for the J-V characteristics of degraded polymer solar cells

    Science.gov (United States)

    Kumar, Pankaj; Gaur, Ankita

    2013-03-01

    An equivalent circuit model was developed for polymer solar cells (PSCs), which explains correctly their behavior under different test conditions. We examine here the validity of that model for degraded PSCs. For that purpose, investigations were carried out on solar cells based on the interpenetrating bulk heterojunctions of poly(3-hehylthiophene) and phenyl[6,6] C61 butyric acid methyl ester. Current density-voltage (J-V) characteristics were measured in dark and under illumination at different time intervals. The characteristics of fresh solar cells are explained well by the developed model, with exponential dependence of photocurrent on applied voltage. However, the degraded characteristics showed space charge limited conduction and the characteristics could be explained well by the same model but with different voltage dependence of photocurrent.

  1. Methods of Measuring Energy Conversion Efficiency in Dye-sensitized Solar Cells

    Science.gov (United States)

    Koide, Naoki; Chiba, Yasuo; Han, Liyuan

    2005-06-01

    The current-voltage characteristics of dye-sensitized solar cells (DSCs) were measured and compared with those of crystalline silicon solar cells. It was found that the energy conversion efficiency of DSCs is dependent on voltage sweep direction and sampling delay time (Td). Measurement of the transient photocurrent revealed that this dependence is due to the longer time constant of DSCs. This dependence was also confirmed in a simulation of current-voltage curves based on an equivalent circuit model of DSCs. Analysis of the current-voltage characteristics of polymer-based bulk heterojunction solar cells (BHSCs) and simulated measurements showed that the longer time constant is due to slow movement of ions in the electrolyte. To improve accuracy, the I-V measurement should be carried out from short circuit to open circuit with Td of 100 ms or longer.

  2. MoO3 Thickness, Thermal Annealing and Solvent Annealing Effects on Inverted and Direct Polymer Photovoltaic Solar Cells

    Directory of Open Access Journals (Sweden)

    Guillaume Wantz

    2012-11-01

    Full Text Available Several parameters of the fabrication process of inverted polymer bulk heterojunction solar cells based on titanium oxide as an electron selective layer and molybdenum oxide as a hole selective layer were tested in order to achieve efficient organic photovoltaic solar cells. Thermal annealing treatment is a common process to achieve optimum morphology, but it proved to be damageable for the performance of this kind of inverted solar cells. We demonstrate using Auger analysis combined with argon etching that diffusion of species occurs from the MoO3/Ag top layers into the active layer upon thermal annealing. In order to achieve efficient devices, the morphology of the bulk heterojunction was then manipulated using the solvent annealing technique as an alternative to thermal annealing. The influence of the MoO3 thickness was studied on inverted, as well as direct, structure. It appeared that only 1 nm-thick MoO3 is enough to exhibit highly efficient devices (PCE = 3.8% and that increasing the thickness up to 15 nm does not change the device performance. 

  3. High efficiency inverted polymer solar cells with the sol–gel derived vanadium oxide interlayer

    International Nuclear Information System (INIS)

    A solution-processable vanadium oxide film was prepared by sol–gel reaction on a bulk-heterojunction and adopted as the hole collection interlayer of inverted polymer solar cells that were based on a blend of commercial low bandgap polymer and [6,6]-phenyl C61 butyric acid methyl ester as the photoactive layer. The developed cell shows an efficiency of 6.29% compare to 6.24% efficiency from the normal devices, the thus-prepared inverted devices demonstrated the feasibility of this alternative approach for developing an ease all-solution route for fabricating air-stable device using low-temperature processes in air ambient. - Highlights: ►A highly efficient inverted polymer solar cell was demonstrated. ►The hole transport interlayer was prepared by a sol–gel derived vanadium oxide. ►The developed cell shows an efficiency of 6.29%.

  4. 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.

  5. All solution processed tandem polymer solar cells based on thermocleavable materials

    Energy Technology Data Exchange (ETDEWEB)

    Hagemann, Ole; Krebs, Frederik C. [Risoe National Laboratory for Sustainable Energy, Polymer Department, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Bjerring, Morten; Nielsen, Niels Chr. [Center for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus C (Denmark)

    2008-11-15

    Multilayer tandem polymer solar cells were prepared by solution processing using thermocleavable polymer materials that allow for conversion to an insoluble state through a short thermal treatment. The problems associated with solubility during application of subsequent layers in the stack were efficiently solved. Devices comprised a transparent front cathode based on solution processed zinc oxide nanoparticles, a large band gap active layer based on a bulk heterojunction between zinc oxide and poly(3-carboxydithiophene) (P3CT) followed by a layer of PEDOT:PSS processed from water. The second cell in the stack employed a zinc oxide front cathode processed on top of the PEDOT:PSS layer from an organic solvent, a low band gap active layer based on a bulk heterojunction between zinc oxide and the novel poly(carboxyterthiophene-co-diphenylthienopyrazine) (P3CTTP) followed by a layer of PEDOT:PSS again processed from water and finally a printed silver electrode. The devices were prepared without the use of fullerenes and vacuum steps and employ only thermal treatments and orthogonal solvents. The devices exhibited operational stability in air without any form of encapsulation. (author)

  6. Aligned carbon nanotube webs as a replacement for indium tin oxide in organic solar cells

    International Nuclear Information System (INIS)

    Bulk heterojunction solar cells were fabricated with flexible webs of aligned multiwalled carbon nanotubes (MWNTs). These webs were drawn from a forest of MWNTs and placed directly onto the device substrate to form the hole collecting electrode. Devices were fabricated on glass substrates with one or two MWNT web layers to study the trade-off between transparency and resistivity on device performance. Devices with two web layers performed better with a fill factor of 0.47 and a device power conversion efficiency of 1.66% due to their higher conductivity. Flexible devices on Mylar substrates were also demonstrated with an efficiency of 1.2% indicating the potential of MWNT webs as a flexible alternative to the more conventional indium tin oxide. - Highlights: ► Drawable carbon nanotube webs were used as an anode in bulk heterojunction cells. ► One and two layers of carbon nanotube webs were compared. ► A thick active layer of ∼ 530 nm was needed to avoid shunting through nanotubes. ► Two layers of web gave the better efficiency of 1.6%. ► Flexible devices on Mylar were demonstrated with 1.2% efficiency

  7. Quantitative analysis of electroluminescence images from polymer solar cells

    Science.gov (United States)

    Seeland, Marco; Rösch, Roland; Hoppe, Harald

    2012-01-01

    We introduce the micro-diode-model (MDM) based on a discrete network of interconnected diodes, which allows for quantitative description of lateral electroluminescence emission images obtained from organic bulk heterojunction solar cells. Besides the distributed solar cell description, the equivalent circuit, respectively, network model considers interface and bulk resistances as well as the sheet resistance of the semitransparent electrode. The application of this model allows direct calculation of the lateral current and voltage distribution within the solar cell and thus accounts well for effects known as current crowding. In addition, network parameters such as internal resistances and the sheet-resistance of the higher resistive electrode can be determined. Furthermore, upon introduction of current sources the micro-diode-model also is able to describe and predict current-voltage characteristics for solar cell devices under illumination. The local nature of this description yields important conclusions concerning the geometry dependent performance and the validity of classical models and equivalent circuits describing thin film solar cells.

  8. Development and characterization of PCDTBT:CdSe QDs hybrid solar cell

    International Nuclear Information System (INIS)

    Solar cell consisting of low band gap polymer poly[N-900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10, 30-benzothiadiazole)] (PCDTBT) as donor and cadmium selenide/zinc sulphide (CdSe/ZnS) core shell quantum dots (QDs) as an acceptor has been developed. The absorption measurements show that the absorption coefficient increases in bulk heterojunction (BHJ) structure covering broad absorption spectrum (200nm–700nm). Also, the photoluminescence (PL) of the PCDTBT:QDs film is found to decrease by an order of magnitude showing a significant transfer of electrons to the QDs. With this approach and under broadband white light with an irradiance of 8.19 mW/cm2, we have been able to achieve a power conversion efficiency (PCE) of 3.1 % with fill factor 0.42 for our typical solar cell

  9. Molecular design and ordering effects in π-functional materials for transistor and solar cell applications

    KAUST Repository

    Beaujuge, Pierre

    2011-12-21

    Organic electronics are broadly anticipated to impact the development of flexible thin-film device technologies. Among these, solution-processable π-conjugated polymers and small molecules are proving particularly promising in field-effect transistors and bulk heterojunction solar cells. This Perspective analyzes some of the most exciting strategies recently suggested in the design and structural organization of π-functional materials for transistor and solar cell applications. Emphasis is placed on the interplay between molecular structure, self-assembling properties, nanoscale and mesoscale ordering, and device efficiency parameters. A critical look at the various approaches used to optimize both materials and device performance is provided to assist in the identification of new directions and further advances. © 2011 American Chemical Society.

  10. Ultrathin oxidized Ti to increase stability and smoothness of Al doped ZnO transparent conductors for high efficiency indium-free polymer solar cells

    Science.gov (United States)

    Formica, N.; Ghosh, D. S.; Martinez-Otero, A.; Chen, T. L.; Martorell, Jordi; Pruneri, V.

    2013-10-01

    We propose a transparent electrode consisting of an aluminum doped zinc oxide (AZO) layer capped with an ultrathin oxidized Ti film for indium-free bulk-heterojunction polymer solar cells (PSCs). The oxidized Ti increases the chemical, environmental, stability and the surface smoothness of AZO while still maintaining its electrical and optical properties. The application potential of the proposed transparent electrode is demonstrated in an inverted PSC, which shows an efficiency of 6.3%, very close to the value (7%) obtained in a similar structure using indium tin oxide. This efficiency is the highest reported to date for PSCs incorporating AZO electrodes.

  11. A comparative study of fluorine substituents for enhanced stability of flexible and ITO-free high-performance polymer solar cells

    DEFF Research Database (Denmark)

    Carlé, Jon Eggert; Helgesen, Martin; Zawacka, Natalia Klaudia;

    2014-01-01

    Two low-band gap polymer series based on benzo[1,2-b:4,5-b?]dithiophene (BDT) and dithienylbenzothiadiazole, with different numbers of fluorine substituents on the 2,3,1-benzothiadiazole unit, have been synthesized and explored in a comparative study of the photochemical stability and operational...... lifetime in flexible large area roll-coated bulk heterojunction solar cells. The two polymer series have different side chains on the BDT unit, namely 2-hexyldecyloxy (BDTHDO) (P1-P3) or 2-hexyldecylthiophene (BDT THD) (P4-P6). The photochemical stability clearly shows that the stability enhances along...

  12. Decohesion Kinetics in Polymer Organic Solar Cells

    KAUST Repository

    Bruner, Christopher

    2014-12-10

    © 2014 American Chemical Society. We investigate the role of molecular weight (MW) of the photoactive polymer poly(3-hexylthiophene) (P3HT) on the temperature-dependent decohesion kinetics of bulk heterojunction (BHJ) organic solar cells (OSCs). The MW of P3HT has been directly correlated to its carrier field effect mobilities and the ambient temperature also affects OSC in-service performance and P3HT arrangement within the BHJ layer. Under inert conditions, time-dependent decohesion readily occurs within the BHJ layer at loads well below its fracture resistance. We observe that by increasing the MW of P3HT, greater resistance to decohesion is achieved. However, failure consistently occurs within the BHJ layer representing the weakest layer within the device stack. Additionally, it was found that at temperatures below the glass transition temperature (∼41-45 °C), decohesion was characterized by brittle failure via molecular bond rupture. Above the glass transition temperature, decohesion growth occurred by a viscoelastic process in the BHJ layer, leading to a significant degree of viscoelastic deformation. We develop a viscoelastic model based on molecular relaxation to describe the resulting behavior. The study has implications for OSC long-term reliability and device performance, which are important for OSC production and implementation.

  13. Poly(3-hexylthiophene)/C{sub 60} heterojunction solar cells: Implication of morphology on performance and ambipolar charge collection

    Energy Technology Data Exchange (ETDEWEB)

    Geiser, Alain [EPFL STI IMX LOMM, PH D2 464 Batiment PH, Station 3, CH 1015 Lausanne (Switzerland); Fan, Bin; Benmansour, Hadjar; Castro, Fernando; Heier, Jakob; Nueesch, Frank; Hany, Roland [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Functional Polymers, Ueberlandstr. 129, CH 8600 Duebendorf (Switzerland); Keller, Beat; Mayerhofer, Karl Emanuel [Empa, Laboratory for Nanoscale Materials Science (Switzerland)

    2008-04-15

    The performance of heterojunction organic solar cells is critically dependent on the morphology of the donor and acceptor components in the active film. We report results of photovoltaic devices consisting of bilayers and bulk heterojunctions using poly(3-hexylthiophene) (P3HT) and Buckminsterfullerene C{sub 60}. White light power efficiencies of {eta}{proportional_to}2.2% (bulk heterojunction) and 2.6% (bilayer) were measured after a thermal annealing step on completed devices. Optical and structural investigations on non-annealed bilayer thin films indicated a distinct porosity of the spin-coated polymer, which allows C{sub 60} to penetrate the P3HT layer and to touch the anode. This resulted for these bilayer solar cells in the experimental observation that electrons were collected predominantly at the cathode after photo-excitation of P3HT, but predominantly at the anode after C{sub 60} excitation. A morphological model to explain the ambipolar charge collection phenomenon is proposed. (author)

  14. 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

  15. Infrared photocurrent response of charge-transfer exciton in polymer bulk heterojunction

    International Nuclear Information System (INIS)

    We study the charge-transfer exciton absorption and photocurrent response in solution-processed bulk heterojunction based on poly(3-hexylthiophene) donor and (6,6)-phenyl-C61-butyric acid methyl ester acceptor in the near-infrared wavelength region. While the exciton absorption exists only for wavelength below 650 nm, direct generation of charge-transfer exciton formed between the donor and acceptor extends the absorption wavelength to 950 nm. For films with micrometer thickness, the photon-to-electron conversion efficiency is about 60% at 750 nm wavelength under reverse voltage bias and the photocurrent to dark current ratio is about 8.6 at 900 nm and remains 3.6 even at 1000 nm. Photodetector with high sensitivity covering exclusively the 650-1000 nm near infrared region can therefore be made without a low bandgap material. The charge-transfer exciton absorption coefficient and photocurrent sensitivity depend on the annealing condition which controls the donor-acceptor morphology

  16. Dielectric nanostructures for broadband light trapping in organic solar cells

    KAUST Repository

    Raman, Aaswath

    2011-09-15

    Organic bulk heterojunction solar cells are a promising candidate for low-cost next-generation photovoltaic systems. However, carrier extraction limitations necessitate thin active layers that sacrifice absorption for internal quantum efficiency or vice versa. Motivated by recent theoretical developments, we show that dielectric wavelength-scale grating structures can produce significant absorption resonances in a realistic organic cell architecture. We numerically demonstrate that 1D, 2D and multi-level ITO-air gratings lying on top of the organic solar cell stack produce a 8-15% increase in photocurrent for a model organic solar cell where PCDTBT:PC71BM is the organic semiconductor. Specific to this approach, the active layer itself remains untouched yet receives the benefit of light trapping by nanostructuring the top surface below which it lies. The techniques developed here are broadly applicable to organic semiconductors in general, and enable partial decoupling between active layer thickness and photocurrent generation. © 2011 Optical Society of America.

  17. Fully Solution-Processed Inverted Polymer Solar Cells with Laminated Nanowire Electrodes

    KAUST Repository

    Gaynor, Whitney

    2010-01-26

    We demonstrate organic photovoltaic cells in which every layer is deposited by solution processing on opaque metal substrates, with efficiencies similar to those obtained in conventional device structures on transparent substrates. The device architecture is enabled by solution-processed, laminated silver nanowire films serving as the top transparent anode. The cells are based on the regioregular poly(3- hexylthiophene) and C 61 butyric acid methyl ester bulk heterojunction and reach an efficiency of 2.5% under 100 mW/cm 2 of AM 1.5G illumination. The metal substrates are adequate barriers to moisture and oxygen, in contrast to transparent plastics that have previously been used, giving rise to the possibility of roll-to-roll solutionprocessed solar cells that are packaged by lamination to glass substrates, combining the cost advantage of roll-toroll processing with the barrier properties of glass and metal foil. © 2010 American Chemical Society.

  18. Solar cells

    Science.gov (United States)

    Cuquel, A.; Roussel, M.

    The physical and electronic characteristics of solar cells are discussed in terms of space applications. The principles underlying the photovoltaic effect are reviewed, including an analytic model for predicting the performance of individual cells and arrays of cells. Attention is given to the effects of electromagnetic and ionizing radiation, micrometeors, thermal and mechanical stresses, pollution and degassing encountered in space. The responses of different types of solar cells to the various performance-degrading agents are examined, with emphasis on techniques for quality assurance in the manufacture and mounting of Si cells.

  19. 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

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

    International Nuclear Information System (INIS)

    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-C61-butyric acid methyl ester (PCDTBT:PC61BM) 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

  1. The influence of polymer purification on the efficiency of poly(3-hexylthiophene):fullerene organic solar cells

    Science.gov (United States)

    Bannock, James H.; Treat, Neil D.; Chabinyc, Michael; Stingelin, Natalie; Heeney, Martin; de Mello, John C.

    2016-01-01

    We report the influence of different polymer purification procedures on the photovoltaic performance of bulk heterojunction solar cells formed from binary blends of poly(3-hexylthiophene) (P3HT) and fullerenes. Selective Soxhlet extractions and metal scavenging agents were used to remove residual monomer, magnesium salt by-products and catalyst from high-weight P3HT (Mw 121 kg/mol, PDI 1.8, RR 99%) synthesised by the Grignard metathesis (GRIM) polymerization route. Using phenyl-C61-butyric acid methyl ester (PC60BM) as an electron acceptor, we observed an increase in average power conversion efficiency from 2.3 to 4.8% in going from crude to fully purified material. Using indene-C60 bisadduct (IC60BA) in place of PC60BM, we observed a further increase to an average value of 6.6% - high for a bulk heterojunction formed from a binary blend of P3HT and C60 fullerene derivatives. PMID:27029994

  2. Ordering effects in benzo[1,2-b:4,5-b']difuran-thieno[3,4-c]pyrrole-4,6- dione polymers with >7% solar cell efficiency

    KAUST Repository

    Warnan, Julien

    2014-05-15

    Benzo[1,2-b:4,5-b\\']difuran-thieno[3,4-c]pyrrole-4,6-dione (PBDFTPD) polymers prepared by microwave-assisted synthesis can achieve power conversion efficiencies (PCEs) >7% in bulk-heterojunction solar cells with phenyl-C61/71-butyric acid methyl ester (PCBM). In "as-cast" PBDFTPD-based devices solution-processed without a small-molecule additive, high PCEs can be obtained in spite of the weak propensity of the polymers to self-assemble and form π-aggregates in thin films. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Electronic excitations in solution-processed oligothiophene small-molecules for organic solar cells.

    Science.gov (United States)

    Gala, F; Mattiello, L; Brunetti, F; Zollo, G

    2016-02-28

    First principles calculations based on density functional theory and many body perturbation theory have been employed to study the optical absorption properties of a newly synthesized oligo-thiophene molecule, with a quaterthiophene central unit, that has been designed for solution-processed bulk-heterojunction solar cells. To this aim we have employed the GW approach to obtain quasiparticle energies as a pre-requisite to solve the Bethe-Salpeter equation for the excitonic Hamiltonian. We show that the experimental absorption spectrum can be explained only by taking into account the inter-molecular transitions among the π-stacked poly-conjugated molecules that are typically obtained in solid-state organic samples. PMID:26931705

  4. Flexible organic/inorganic hybrid solar cells based on conjugated polymer and ZnO nanorod array

    International Nuclear Information System (INIS)

    We report on the photovoltaic characteristics of organic/inorganic hybrid solar cells fabricated on ‘flexible’ transparent substrates. The solar cell device is composed of ZnO nanorod array and the bulk heterojunction structured organic layer which is the blend of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM). The ZnO nanorod array was grown on indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates via a low-temperature (85 °C) aqueous solution process. The blend solution consisting of conjugated polymer P3HT and fullerene PCBM was spin coated at a low spinning rate of 400 rpm on top of the ZnO nanorod array structure and then the photoactive layer was slow dried at room temperature in air to promote its infiltration into the nanorod network. As a top electrode, silver was sputtered on top of the photoactive layer. The flexible solar cell with the structure of PET/ITO/ZnO thin film/ZnO nanorods/P3HT:PCBM/Ag exhibited a photovoltaic performance with an open circuit voltage (VOC) of 0.52 V, a short circuit current density (JSC) of 9.82 mA cm−2, a fill factor (FF) of 35% and a power conversion efficiency (η) of 1.78%. All the measurements were performed under 100 mW cm−2 of illumination with an air mass 1.5 G filter. To the best of our knowledge, this is the first presentation of investigation into the fabrication and characterization of organic/inorganic hybrid solar cells based on bulk heterojunction structured conjugated polymer/fullerene photoactive layer and ZnO nanorod array constructed on flexible transparent substrates. (paper)

  5. Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory

    Science.gov (United States)

    Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

    2015-11-01

    The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells.

  6. Morphology and Performance of Polymer Solar Cell Characterized by DPD Simulation and Graph Theory.

    Science.gov (United States)

    Du, Chunmiao; Ji, Yujin; Xue, Junwei; Hou, Tingjun; Tang, Jianxin; Lee, Shuit-Tong; Li, Youyong

    2015-01-01

    The morphology of active layers in the bulk heterojunction (BHJ) solar cells is critical to the performance of organic photovoltaics (OPV). Currently, there is limited information for the morphology from transmission electron microscopy (TEM) techniques. Meanwhile, there are limited approaches to predict the morphology /efficiency of OPV. Here we use Dissipative Particle Dynamics (DPD) to determine 3D morphology of BHJ solar cells and show DPD to be an efficient approach to predict the 3D morphology. Based on the 3D morphology, we estimate the performance indicator of BHJ solar cells by using graph theory. Specifically, we study poly (3-hexylthiophene)/[6, 6]-phenyl-C61butyric acid methyl ester (P3HT/PCBM) BHJ solar cells. We find that, when the volume fraction of PCBM is in the region 0.4 ∼ 0.5, P3HT/PCBM will show bi-continuous morphology and optimum performance, consistent with experimental results. Further, the optimum temperature (413 K) for the morphology and performance of P3HT/PCBM is in accord with annealing results. We find that solvent additive plays a critical role in the desolvation process of P3HT/PCBM BHJ solar cell. Our approach provides a direct method to predict dynamic 3D morphology and performance indicator for BHJ solar cells. PMID:26581407

  7. Film stresses and electrode buckling in organic solar cells

    KAUST Repository

    Brand, Vitali

    2012-08-01

    We investigate the film stresses that develop in the polymer films and metal electrodes of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells. A compressive biaxial stress of ∼-36 MPa was measured in PEDOT:PSS while a tensile stress of ∼6 MPa was measured in the BHJ layer. We then analyze the effect of electrode deposition rate on the film stresses in the Al electrode. Compressive stresses of ∼-100 to -145 MPa in the Al electrode lead to a buckling instability resulting in undulating electrode surface topography. The BHJ layer was found to have the lowest cohesion (∼1.5-1.8 J/m 2) among the layers of the solar cell and dependent on the Al electrode deposition rate. The cohesive failure path in the BHJ layer exhibited the same periodicity and orientation of the Al electrode buckling topography. We discuss the implications of the film stresses on damage processes during device fabrication and operation. © 2012 Elsevier B.V. All rights reserved.

  8. Solar cells

    International Nuclear Information System (INIS)

    A method of producing solar cells is described which consists of producing a substantially monocrystalline tubular body of silicon or other suitable semiconductor material, treating this body to form an annular rectifying junction and then cutting it longitudinally to form a number of nearly flat ribbons from which the solar cells are fabricated. The P=N rectifying junction produced by the formation of silicon dioxide on the layers at the inner and outer surfaces of the body can be formed by ion-implantation or diffusion. (U.K.)

  9. Thermally induced vertical phase separation and photovoltaic characteristics of polymer solar cells for P3HT/PCBM composites

    Science.gov (United States)

    Nagai, Masaru; Wei, Huang; Yoshida, Yuji

    2016-06-01

    The occurrence of vertical phase separation has been reported for various spin-cast polymer films, including bulk-heterojunction films of polymer solar cells (PSCs). Focusing on real-space analysis, we conducted a study on the relationship between the morphology and processing conditions of PSCs for typical poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) cells. Our results demonstrated that spin-casting caused a localized reduction in the P3HT concentration in the bulk center. Thermal annealing after cathode formation enhanced the unevenness in concentration and created a multilayered vertical phase-separated morphology in which the P3HT domains were gathered near the electrodes, leaving only PCBM domains at the center of the film. Cells with this morphology had good power conversion efficiency (∼3%).

  10. Solar cells

    Science.gov (United States)

    Treble, F. C.

    1980-11-01

    The history, state of the art, and future prospects of solar cells are reviewed. Solar cells are already competitive in a wide range of low-power applications, and during the 1980's they are expected to become cheaper to run than diesel or gasoline generators, the present mainstay of isolated communities. At this stage they will become attractive for water pumping, irrigation, and rural electrification, particularly in developing countries. With further cost reduction, they may be used to augment grid supplies in domestic, commercial, institutional, and industrial premises. Cost reduction to the stage where photovoltaics becomes economic for large-scale power generation in central stations depends on a technological breakthrough in the development of thin-film cells. DOE aims to reach this goal by 1990, so that by the end of the century about 20% of the estimated annual additions to their electrical generating capacity will be photovoltaic.

  11. 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.

  12. Silver Nanoparticles in PEDOT:PSS Layer for Polymer Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Agnieszka Iwan

    2015-01-01

    Full Text Available We compare the performance of polymer solar cells based on poly(3-hexylthiophene (P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM with silver nanoparticles (Ag NPs incorporated in poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS. The structure of constructed solar devices was ITO/PEDOT:PSS:Ag NPs/P3HT:PCBM/Al. Typical polyol chemistry was used to synthesize silver in water solution. Ag nanoparticles were investigated by UV-vis, atomic force microscopy (AFM, and dynamic light scattering (DLS methods. We investigated influence of amount of silver in a hole transporting layer on the performance of bulk heterojunction polymer solar cells. The value of power conversion efficiency (PCE, equal to 2.16% under simulated 100 mW/cm2 AM 1.5G irradiation, was found for device created in air with 60 µL of Ag NPs added to 1 mL of PEDOT:PSS. Along with the increase amount of Ag NPs from 60 to 150 µL, the PCE decrease was found. Stability of solar cells with Ag was also investigated. The loss in value of PCE after 8 months was found in the range 13–47% depending on the device architecture. The solar cells were additionally measured with impedance spectroscopy.

  13. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    Science.gov (United States)

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong

    2015-12-01

    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn2SnO4 nanowires/Cu4Bi4S9 (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  14. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    International Nuclear Information System (INIS)

    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn2SnO4 nanowires/Cu4Bi4S9 (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future

  15. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangyang, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn [Institute of Microsystems Physics and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2015-12-14

    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn{sub 2}SnO{sub 4} nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  16. Fullerene-based materials for solar cell applications: design of novel acceptors for efficient polymer solar cells--a DFT study.

    Science.gov (United States)

    Mohajeri, Afshan; Omidvar, Akbar

    2015-09-14

    Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Polymer solar cells (PSCs) hold promise for their potential to be used as low-cost and efficient solar energy converters. PSCs have been commonly made from bicontinuous polymer:fullerene composites or so-called bulk heterojunctions. The conjugated polymer donors and the fullerene derivative acceptors are the key materials for high performance PSCs. In the present study, we have performed density functional theory calculations to investigate the electronic structures and magnetic properties of several representative C60 fullerene derivatives, seeking ways to improve their efficiency as acceptors of photovoltaic devices. In our survey, we have successfully correlated the LUMO energy level as well as chemical hardness, hyper-hardness, nucleus-independent chemical shift, and static dipole polarizability of PC60BM-like fullerene derivative acceptors with the experimental open circuit voltage of the photovoltaic device based on the P3HT:fullerene blend. The obtained structure-property correlations allow finding the best fullerene acceptor match for the P3HT donor. For this purpose, four new fullerene derivatives are proposed and the output parameters for the corresponding P3HT-based devices are predicted. It is found that the proposed fullerene derivatives exhibit better photovoltaic properties than the traditional PC60BM acceptor. The present study opens the way for manipulating fullerene derivatives and developing promising acceptors for solar cell applications. PMID:26248255

  17. Graphene composite for improvement in the conversion efficiency of flexible poly 3-hexyl-thiophene:[6,6]-phenyl C71 butyric acid methyl ester polymer solar cells

    International Nuclear Information System (INIS)

    The solution of thin graphene-sheets obtained from a simple ultrasonic exfoliation process was found to chemically interact with [6,6]-phenyl C71 butyric acid methyl ester (PCBM) molecules. The thinner graphene-sheets have significantly altered the positions of highest occupied molecular orbital and lowest unoccupied molecular orbital of PCBM, which is beneficial for the enhancement of the open circuit voltage of the solar cells. Flexible bulk heterojunction solar cells fabricated using poly 3-hexylthiophene (P3HT):PCBM-graphene exhibited a power conversion efficiency of 2.51%, which is a ∼2-fold increase as compared to those fabricated using P3HT:PCBM. Inclusion of graphene-sheets not only improved the open-circuit voltage but also enhanced the short-circuit current density owing to an improved electron transport

  18. Utilizing insulating nanoparticles as the spacer in laminated flexible polymer solar cells for improved mechanical stability.

    Science.gov (United States)

    Lu, Yunzhang; Alexander, Clement; Xiao, Zhengguo; Yuan, Yongbo; Zhang, Runyu; Huang, Jinsong

    2012-08-31

    Roll-to-roll lamination is one promising technique to produce large-area organic electronic devices such as solar cells with a large through output. One challenge in this process is the frequent electric point shorting of the cathode and anode by the excess or concentrated applied stress from many possible sources. In this paper, we report a method to avoid electric point shorting by incorporating insulating and hard barium titanate (BaTiO(3)) nanoparticles (NPs) into the active layer to work as a spacer. It has been demonstrated that the incorporated BaTiO(3) NPs in poly(3-hexylthiophene):[6,6]-phenyl-c-61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction solar cells cause no deleterious effect to the power conversion process of this type of solar cell. The resulting laminated devices with NPs in the active layer display the same efficiency as the devices without NPs, while the laminated devices with NPs can sustain a ten times higher lamination stress of over 6 MPa. The flexible polymer solar cell device with incorporated NPs shows a much smaller survivable curvature radius of 4 mm, while a regular flexible device can only sustain a bending curvature radius of 8 mm before fracture. PMID:22886059

  19. Hybrid solar cells based on semiconductor nanocrystals and poly(3-hexylthiophene)

    International Nuclear Information System (INIS)

    Semiconductor nanoparticles are promising electron acceptor materials for polymer-based bulk heterojunction solar cells. Size-dependent optical properties enable adaptation of the absorption to the solar spectrum, and the possibility to use elongated nanoparticles should be favorable for efficient electron transport. Despite these potential advantages, efficiencies reported for such hybrid solar cells are still below those of organic polymer/fullerene cells. In the presented work, CdSe nanoparticles were prepared by colloidal chemistry and their usability for hybrid solar cells in conjunction with poly(3-hexylthiophene) (P3HT) as electron donor material was studied. Systematic studies of correlations between the device performance and blend morphology are presented. Furthermore, charge separation in the donor/acceptor systems was studied in detail by electron spin resonance (ESR) and photoinduced absorption spectroscopy (PIA). The studies revealed the existence of a large amount of trap states which might be the origin of the limitations for the device efficiency. First results with colloidally prepared CuInS2 nanoparticles are presented as well.

  20. Understanding polycarbazole-based polymer:CdSe hybrid solar cells

    International Nuclear Information System (INIS)

    We report for the first time the fabrication and characterization of organic–inorganic bulk heterojunction (BHJ) hybrid solar cells made of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′-benzothiadiazole)] (PCDTBT) and pyridine-capped CdSe nanorods. By optimizing both CdSe loading and active layer film thickness, the power conversion efficiencies (PCEs) of PCDTBT:CdSe hybrid solar cells were able to reach 2%, with PCDTBT:CdSe devices displaying an open-circuit voltage (VOC) that is 35% higher than P3HT:CdSe devices due to the deeper HOMO level of PCDTBT polymer. The performance of PCDTBT:CdSe devices is limited by its morphology and also its lower LUMO energy offset compared to P3HT:CdSe devices. Hence, the performance of PCDTBT:CdSe solar cells could be further improved by modifying the morphology of the films and also by including an interlayer to generate a built-in voltage to encourage exciton dissociation. Our results suggest that PCDTBT could be a viable alternative to P3HT as an electron donor in hybrid BHJ solar cells for high photovoltage application. (paper)

  1. 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.

  2. Thermocleavable materials for polymer solar cells with high open circuit voltage-a comparative study.

    Science.gov (United States)

    Tromholt, Thomas; Gevorgyan, Suren A; Jørgensen, Mikkel; Krebs, Frederik C; Sylvester-Hvid, Kristian O

    2009-12-01

    The search for polymer solar cells giving a high open circuit voltage was conducted through a comparative study of four types of bulk-heterojunction solar cells employing different photoactive layers. As electron donors the thermo-cleavable polymer poly-(3-(2-methylhexyloxycarbonyl)dithiophene) (P3MHOCT) and unsubstituted polythiophene (PT) were used, the latter of which results from thermo cleaving the former at 310 degrees C. As reference, P3HT solar cells were built in parallel. As electron acceptors, either PCBM or bis-[60]PCBM were used. In excess of 300 solar cells were produced under as identical conditions as possible, varying only the material combination of the photo active layer. It was observed that on replacing PCBM with bis[60]PCBM, the open circuit voltage on average increased by 100 mV for P3MHOCT and 200 mV for PT solar cells. Open circuit voltages approaching 1 V were observed for the PT:bis[60]PCBM solar cells and a maximum conversion efficiency of 1.3% was obtained for solar cells with P3MHOCT:PCBM as the photoactive material. For the reference solar cells maximum efficiencies of 2.1 and 2.4% were achieved for P3HT:PCBM and P3HT:bis[60]PCBM, respectively. Despite special measures taken in terms of substrate design and device processing, a substantial spread in the photovoltaic properties was generally observed. This spread could not be correlated with the optical properties of the solar cells, the thickness of the photo active layer or the electrode deposition conditions of the aluminum top electrode. PMID:20356155

  3. 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.

  4. Aryl end-capped quaterthiophenes applied as anode interfacial layers in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Heiskanen, Juha P., E-mail: juha.heiskanen@oulu.fi [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Manninen, Venla M. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Pankov, Dmitri [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Omar, Walaa A.E. [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland); Department of Chemistry and Mathematics, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43721 (Egypt); Kastinen, Tuuva; Hukka, Terttu I.; Lemmetyinen, Helge J. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere (Finland); Hormi, Osmo E.O. [Department of Chemistry, P.O. Box 3000, FI-90014 University of Oulu (Finland)

    2015-01-01

    Four aryl end-capped quaterthiophene derivatives were synthesized and their material properties were studied by computational, spectroscopic, electrochemical, and thermoanalytical methods. Compounds were applied as interfacial layers between the bulk heterojunction active layer and Ag anode in inverted organic solar cells. Results show that p-cyanophenyl end-capped quaterthiophene with hexyl side chains increases both the short circuit current density and power conversion efficiency notably compared to reference interlayer material, tris-(8-hydroxyquinoline)aluminum. The improved cell performance was attributed to the optimal positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital (LUMO) of this material, relative to those of the photoactive electron donor poly(3-hexylthiophene) and Ag anode, and evenly distributed LUMO. In addition, the use of these materials as an anode interfacial layer increases the absorption of the solar cell, which could contribute to the formation of excitons and additional current production by the cell. - Highlights: • Aryl end-capped oligothiophenes were synthesized in good overall yields. • Materials could be applied as anode interfacial layers in organic solar cells. • Computational, spectroscopic, and electrochemical analyses support conclusions. • Substitution patterns determine HOMO and LUMO levels of interfacial material. • Improved cell performance was attributed mainly to optimal HOMO and LUMO levels.

  5. Aryl end-capped quaterthiophenes applied as anode interfacial layers in inverted organic solar cells

    International Nuclear Information System (INIS)

    Four aryl end-capped quaterthiophene derivatives were synthesized and their material properties were studied by computational, spectroscopic, electrochemical, and thermoanalytical methods. Compounds were applied as interfacial layers between the bulk heterojunction active layer and Ag anode in inverted organic solar cells. Results show that p-cyanophenyl end-capped quaterthiophene with hexyl side chains increases both the short circuit current density and power conversion efficiency notably compared to reference interlayer material, tris-(8-hydroxyquinoline)aluminum. The improved cell performance was attributed to the optimal positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital (LUMO) of this material, relative to those of the photoactive electron donor poly(3-hexylthiophene) and Ag anode, and evenly distributed LUMO. In addition, the use of these materials as an anode interfacial layer increases the absorption of the solar cell, which could contribute to the formation of excitons and additional current production by the cell. - Highlights: • Aryl end-capped oligothiophenes were synthesized in good overall yields. • Materials could be applied as anode interfacial layers in organic solar cells. • Computational, spectroscopic, and electrochemical analyses support conclusions. • Substitution patterns determine HOMO and LUMO levels of interfacial material. • Improved cell performance was attributed mainly to optimal HOMO and LUMO levels

  6. Characterization of the dominating bulk recombination in bulk-heterojunction blends using photoinduced absorption

    Science.gov (United States)

    Sandén, S.; Wilson, N. M.; Sandberg, O. J.; Ã-sterbacka, R.

    2016-05-01

    In this work we show how to clarify the dominating bulk recombination in organic solar cells by using photoinduced absorption. We show how to use the intensity and frequency dependence of the in-phase and quadrature signals to obtain the effective reaction order. For trap-assisted recombination, we can show using a multiple trapping and retrapping model with an exponential tail-state distribution that a temperature dependent reaction order is obtained which allows for determination of the characteristic energy of the exponential distribution of trap-states. In the model system pBTTT:PC60BM, we show that trap-assisted recombination is the dominating bulk recombination in 1:1 blends with a characteristic energy of the exponential trap distribution E c h = 44 ± 5 meV. The 1:4 blend, on the other hand, shows temperature independent behavior in good agreement with a dominating 2D Langevin bulk recombination.

  7. Eco-friendly spray coating of organic solar cells through water-based nanoparticles ink (Presentation Recording)

    Science.gov (United States)

    Stryckers, Jeroen; D'Olieslaeger, Lien; Manca, Jean; Ethirajan, Anitha; Deferme, Wim

    2015-09-01

    Ultrasonic spray coating is currently proven to be a reliable, flexible and cost efficient fabrication method for printed electronics [1-2]. Ultrasonic nozzles are by design especially well-suited to deposit nano-suspension dispersions. Due to the ultrasonic vibration of the nozzle, droplets having a median diameter of 20 μm are created in a homogeneous droplet cloud and directed towards the substrate. When one prepares an ink having the right wetting properties, thin and homogeneous layers, fully covering the surface, can be achieved. Together with conjugated polymer nanoparticles (NPs), emerging as a new class of nanomaterials, [3] it opens possibilities towards eco-friendly roll-to-roll processing of state-of-the-art organic bulk heterojunction solar cells. A ultrasonic spray coater was used to print the conjugated polymer NP layers under different conditions. A first optimization of the spray coater settings (flow rate, spray speed and temperature) and the ink formulation (water and co-solvent mixture and NP content) was performed for polystyrene particles dissolved in a water-ethanol mixture. As a next step, the low bandgap donor polymer poly[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophene-diyl] (PCDTBT) [4] and the fullerene acceptor phenyl-C71-butyric acid methyl ester (PCBM[70]) were combined in a water-based blend NP dispersion which was prepared using the mini-emulsion technique. [5,6] Optical Microscopy, profilometry and Scanning Electron Microscopy (SEM) are performed to study the roughness, surface structure, thickness and coverage of the spray coated layers. Finally the printed NP layers are integrated in organic bulk heterojunction solar cells and compared to spin coated reference devices.

  8. MoO3/poly(9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine) double-interlayer effect on polymer solar cells

    Science.gov (United States)

    Subbiah, Jegadesan; Kim, Do Young; Hartel, Michael; So, Franky

    2010-02-01

    A double interlayer composed of MoO3 and poly(9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine) (TFB) was used as an anode contact for bulk heterojunction polymer solar cells. Using this strategy, photovoltaic cells with poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene]: [6,6]-phenyl-C61 butyric acid methyl ester (MDMO-PPV:PCBM) blend as a photoactive layer were fabricated. An enhancement in power conversion efficiency of 53% was observed in cells with a double interlayer compared with cells having a PEDOT: PSS interlayer. The enhancement is attributed to the combined effects of electron blocking and enhanced charge extraction from the photoactive layer to the anode.

  9. Reduced energy offset via substitutional doping for efficient organic/inorganic hybrid solar cells.

    Science.gov (United States)

    Jin, Xiao; Sun, Weifu; Zhang, Qin; Ruan, Kelian; Cheng, Yuanyuan; Xu, Haijiao; Xu, Zhongyuan; Li, Qinghua

    2015-06-01

    Charge carrier transport in bulk heterojunction that is central to the device performance of solar cells is sensitively dependent on the energy level alignment of acceptor and donor. However, the effect of energy level regulation induced by nickel ions on the primary photoexcited electron transfer and the performance of P3HT/TiO2 hybrid solar cells remains being poorly understood and rarely studied. Here we demonstrate that the introduction of the versatile nickel ions into TiO2 nanocrystals can significantly elevate the conduction and valence band energy levels of the acceptor, thus resulting in a remarkable reduction of energy level offset between the conduction band of acceptor and lowest unoccupied molecular orbital of donor. By applying transient photoluminescence and femtosecond transient absorption spectroscopies, we demonstrate that the electron transfer becomes more competitive after incorporating nickel ions. In particular, the electron transfer life time is shortened from 30.2 to 16.7 ps, i.e., more than 44% faster than pure TiO2 acceptor, thus leading to a notable increase of power conversion efficiency in organic/inorganic hybrid solar cells. This work underscores the promising virtue of engineering the reduction of 'excess' energy offset to accelerate electron transport and demonstrates the potential of nickel ions in applications of solar energy conversion and photon detectors. PMID:26072869

  10. Interlayer adhesion in roll-to-roll processed flexible inverted polymer solar cells

    KAUST Repository

    Dupont, Stephanie R.

    2012-02-01

    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 demonstrate how a thin-film adhesion technique can be applied to flexible organic solar cells to obtain quantitative adhesion values. For the P3HT:PCBM-based BHJ polymer solar cells, the interface of the BHJ with the conductive polymer layer PEDOT:PSS was found to be the weakest. The adhesion fracture energy varied from 1.6 J/m2 to 0.1 J/m2 depending on the composition of the P3HT:PCBM layer. Post-deposition annealing time and temperature were shown to increase the adhesion at this interface. Additionally the PEDOT:PSS cells are compared with V2O5 cells whereby adhesive failure marked by high fracture energies was observed. © 2011 Elsevier B.V.

  11. Triphenylamine-based amorphous polymers for bulk-heterojunction photovoltaic cells

    International Nuclear Information System (INIS)

    In this paper, the recent research progress on triphenylamine (TPA)-based donor-acceptor (D-A) amorphous polymers including our developed polymers is reviewed. TPA has three-dimensional branched structures and can provide D-A polymers containing D and A units in the main chain or side chain. The use of TPA-based amorphous polymers in the fabrication of organic photovoltaics (OPVs) offers great advantages over the use of a polycrystalline film in terms of high reproducibility of the OPV performance. The amorphous polymer design using TPA, therefore, indicates a promising direction for the development of new donor materials in OPVs

  12. Influence of morphology of PCDTBT:PC71BM on the performance of solar cells

    Science.gov (United States)

    Zhao, Ling; Zhao, Suling; Xu, Zheng; Gong, Wei; Yang, Qianqian; Fan, Xing; Xu, Xurong

    2014-03-01

    Because of the restriction of low energy difference between the highest occupied molecular orbital of P3HT and the lowest unoccupied molecular orbital of PCBM, the obtained power conversion efficiency of P3HT:PCBM solar cells is merely half the ideal value. In this paper, we have fabricated bulk heterojunction solar cells based on PCDTBT and PC71BM (structure: ITO/PEDOT:PSS/PCDTBT:PC71BM/LiF (0.8 nm)/Al (80 nm)). In order to optimize the performance of the cells, the weight ratio of PCDTBT to PC71BM, the thickness of the active layer and thermal annealing are investigated. When the weight ratio of PCDTBT to PC71BM is 1:2 and the thickness of the active layer is 73 nm, a short circuit current density of 10.36 mA/cm2, an open-circuit voltage of 0.91 V, a fill factor of 55.06 % and a power conversion efficiency of 5.19 % can be achieved. Moreover, we probe the influence of annealing temperature on the performance of organic solar cells, and find that the thermal treatment methodology (apart from the removal of trapped casting solvent) is of limited benefit.

  13. Polymer solar cells based on poly(3-hexylthiophene) and fullerene: Pyrene acceptor systems

    Energy Technology Data Exchange (ETDEWEB)

    Cominetti, Alessandra; Pellegrino, Andrea; Longo, Luca [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Po, Riccardo, E-mail: riccardo.po@eni.com [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Tacca, Alessandra; Carbonera, Chiara; Salvalaggio, Mario [Research Center for Renewable Energies and Environment, Istituto Donegani, Eni S.p.A, Via Fauser 4, IT-28100 Novara (Italy); Baldrighi, Michele; Meille, Stefano Valdo [Dipartimento di Chimica, Materiali e Ingegneria Chimica “G. Natta”, Politecnico di Milano, via Mancinelli 7, IT-20131 Milano (Italy)

    2015-06-01

    The replacement of widely used fullerene derivatives, e.g. [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), with unfunctionalized C60 and C70 is an effective approach to reduce the costs of organic photovoltaics. However, solubility issues of these compounds have always represented an obstacle to their use. In this study, bulk-heterojunction solar cells made of poly(3-hexylthiophene) donor polymer, C60 or C70 acceptors and a pyrene derivative (1-pyrenebutiric acid butyl ester) are reported. Butyl 1-pyrenebutirate limits the aggregation of fullerenes and improves the active layer morphology, plausibly due to the formation of pyrene-fullerene complexes which, in the case of pyrene-C70, were also obtained in a crystalline form. Maximum power conversion efficiencies of 1.54% and 2.50% have been obtained using, respectively, C60 or C70 as acceptor. Quantum mechanical modeling provides additional insight into the formation of plausible supermolecular structures via π-π interactions and on the redox behaviour of pyrene-fullerene systems. - Highlights: • Pyrene derivatives favour the dispersion of unfunctionalized fullerenes. • Polymer solar cells with pyrene: C60 adduct as acceptor have efficiencies of 1.54%. • When C60 is substituted with C70 the efficiency is increased to 2.50%. • DFT calculations support the plausibility of the formation of pyrene: fullerene adducts. • The use of unfunctionalized fullerenes may decrease the costs of polymer solar cells.

  14. Polymer solar cells based on poly(3-hexylthiophene) and fullerene: Pyrene acceptor systems

    International Nuclear Information System (INIS)

    The replacement of widely used fullerene derivatives, e.g. [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), with unfunctionalized C60 and C70 is an effective approach to reduce the costs of organic photovoltaics. However, solubility issues of these compounds have always represented an obstacle to their use. In this study, bulk-heterojunction solar cells made of poly(3-hexylthiophene) donor polymer, C60 or C70 acceptors and a pyrene derivative (1-pyrenebutiric acid butyl ester) are reported. Butyl 1-pyrenebutirate limits the aggregation of fullerenes and improves the active layer morphology, plausibly due to the formation of pyrene-fullerene complexes which, in the case of pyrene-C70, were also obtained in a crystalline form. Maximum power conversion efficiencies of 1.54% and 2.50% have been obtained using, respectively, C60 or C70 as acceptor. Quantum mechanical modeling provides additional insight into the formation of plausible supermolecular structures via π-π interactions and on the redox behaviour of pyrene-fullerene systems. - Highlights: • Pyrene derivatives favour the dispersion of unfunctionalized fullerenes. • Polymer solar cells with pyrene: C60 adduct as acceptor have efficiencies of 1.54%. • When C60 is substituted with C70 the efficiency is increased to 2.50%. • DFT calculations support the plausibility of the formation of pyrene: fullerene adducts. • The use of unfunctionalized fullerenes may decrease the costs of polymer solar cells

  15. Organic solar cells with graded absorber layers processed from nanoparticle dispersions

    Science.gov (United States)

    Gärtner, Stefan; Reich, Stefan; Bruns, Michael; Czolk, Jens; Colsmann, Alexander

    2016-03-01

    The fabrication of organic solar cells with advanced multi-layer architectures from solution is often limited by the choice of solvents since most organic semiconductors dissolve in the same aromatic agents. In this work, we investigate multi-pass deposition of organic semiconductors from eco-friendly ethanol dispersion. Once applied, the nanoparticles are insoluble in the deposition agent, allowing for the application of further nanoparticulate layers and hence for building poly(3-hexylthiophene-2,5-diyl):indene-C60 bisadduct absorber layers with vertically graded polymer and conversely graded fullerene concentration. Upon thermal annealing, we observe some degrees of polymer/fullerene interdiffusion by means of X-ray photoelectron spectroscopy and Kelvin probe force microscopy. Replacing the common bulk-heterojunction by such a graded photo-active layer yields an enhanced fill factor of the solar cell due to an improved charge carrier extraction, and consequently an overall power conversion efficiency beyond 4%. Wet processing of such advanced device architectures paves the way for a versatile, eco-friendly and industrially feasible future fabrication of organic solar cells with advanced multi-layer architectures.

  16. Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

    Directory of Open Access Journals (Sweden)

    Yasser A. M. Ismail

    2011-01-01

    Full Text Available We have fabricated bulk heterojunction organic solar cells using coumarin 6 (C6 as a small organic dye, for light harvesting and electron donation, with fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM, acting as an electron acceptor, by spin-coating technique. We have investigated thermal annealing and blend concentration effects on light harvesting, photocurrent, and performance parameters of the solar cells. In this work, we introduced an experimental method by which someone can easily detect the variation in the contact between active layer and cathode due to thermal annealing after cathode deposition. We have showed, in this work, unusual behavior of solar cell composed of small organic molecules under the influence of thermal annealing at different conditions. This behavior seemed uncommon for polymer solar cells. We try from this work to understand device physics and to locate a relationship between production parameters and performance parameters of the solar cell based on small organic molecules.

  17. 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

  18. Influence of Blend Ratio and Processing Additive on Free Carrier Yield and Mobility in PTB7:PC71BM Photovoltaic Solar Cells

    Science.gov (United States)

    2016-01-01

    Charge separation and extraction dynamics were investigated in high-performance bulk heterojunction solar cells made from the polymer PTB7 and the soluble fullerene PC71BM on a broad time scale from subpicosecond to microseconds using ultrafast optical probing of carrier drift and the integral-mode photocurrent measurements. We show that the short circuit current is determined by the separation of charge pairs into free carriers, which is strongly influenced by blend composition. This separation is found to be efficient in fullerene-rich blends where a high electron mobility of >0.1 cm2 V–1 s–1 is observed in the first 10 ps after excitation. Morphology optimization using the solvent additive 1,8-diiodooctane (DIO) doubles the charge pair separation efficiency and the short-circuit current. Carrier extraction at low internal electric field is slightly faster from the cells prepared with DIO, which can reduce recombination losses and enhance a fill factor. PMID:27293495

  19. Polymer solar cells. Morphology-property-correlation; Polymere Solarzellen. Morphologie-Eigenschafts-Korrelation

    Energy Technology Data Exchange (ETDEWEB)

    Erb, Tobias

    2008-09-22

    The aim of the presented dissertation is to clarify open questions concerning the development and control of the morphology in the active layer of polymer bulk heterojunction solar cells. The new findings hereby derived shall modify the existing models of the active layer morphology as found in today's literature. The experimental investigations were performed by X-ray diffraction, spectroscopic ellipsometry, and photoluminescence spectroscopy. In addition to those methods, light microscopy and differential scanning calorimetry were applied to investigate three chosen material systems: P3HT/PCBM-C{sub 60}, P3HT/MDHE-C{sub 60}, and P3HT/(MDHE){sub 2}-C{sub 60}. On the basis of experimental results a morphological model is developed, which is discussed in the context of existing literature. The solar cells were electrically characterised by current-voltage and external quantum efficiency measurements. The structural model is set into relation with photovoltaic parameters of the polymer solar cell, such as short circuit photocurrent, open circuit voltage, fill factor, and power conversion efficiency. This contributes to the explanation and analysis of the electrical properties of the organic solar cell as a device. In summary, this work yields morphology-property-relations that are able to explain the interaction between physical properties, such as light absorption, charge carrier generation, and transport, with the morphology present within the active layer. Finally, the three investigated systems are compared and evaluated with respect to their applicability in polymer solar cells. Further on, the morphology-propertyrelations are used to develop a strategy to estimate the suitability of new twocomponent polymer-fullerene donor-acceptor systems for polymer solar cells. Based on these findings it becomes possible to evaluate the optimization potential for new materials. In conclusion, this helps to develop polymer solar cells with increased power conversion

  20. A way for studying the impact of PEDOT:PSS interface layer on carrier transport in PCDTBT:PC71BM bulk hetero junction solar cells by electric field induced optical second harmonic generation measurement

    International Nuclear Information System (INIS)

    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:PC71BM bulk heterojunction (BHJ) organic solar cells (OSCs). We revealed that the electric fields in the PCDTBT and PC71BM 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:PC71BM 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

  1. 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.

  2. Design Principles in Polymer-Fullerene BHJ Solar Cells: PBDTTPD as a Case Study

    KAUST Repository

    Beaujuge, Pierre

    2015-06-29

    Among Organic Electronics, solution-processable π-conjugated polymers are proving particularly promising in bulk-heterojunction (BHJ) solar cells with fullerene acceptors such as PCBM.[1] In recent years, great headway has been made in the development of efficient polymer donors across the community, with published power conversion efficiencies (PCE) >8% in single cells and >10% in tandems. In most reports, these systems involve elaborate repeat unit and side chain patterns, and deviating from those patterns induces substantial drops in device PCE. While the range of polymer design parameters that impact BHJ solar cell performance remains a matter of some debate, our recent developments indicate that the combination of side-chain substituents appended to the main chain critically impacts polymer performance. For example, in poly(benzo[1,2-b:4,5-b’]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD), side-chain substituents of various size and branching impart distinct molecular packing distances (i.e., π–π stacking and lamellar spacing), varying degrees of nanostructural order in thin films, and preferential backbone orientation relative to the device substrate.[2-5] While these structural variations seem to correlate with BHJ solar cell performance, with power conversion efficiencies ranging from 4% to 8.5%,[2,3] we believe that other contributing parameters – such as the local conformations between the polymer and the fullerene, and the domain distribution/composition across the BHJ (i.e., pure/mixed phases) – should also be taken into account.[6,7] Other discrete modifications of PBDTTPD’s molecular structure affect polymer performance in BHJ solar cells with PCBM, and our recent developments emphasize how systematic structure-property relationship studies impact the design of efficient polymer donors for BHJ solar cell applications.[8-10] It is important to further our understanding of these effects as we look to continue improving BHJ solar

  3. 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.

  4. High-efficiency bulk heterojunction memory devices fabricated using organometallic halide perovskite:poly(N-vinylcarbazole) blend active layers.

    Science.gov (United States)

    Wang, Cheng; Chen, Yu; Zhang, Bin; Liu, Shanshan; Chen, Qibin; Cao, Yaming; Sun, Sai

    2016-01-14

    A solution-processed organometallic halide perovskite-based bulk heterojunction (BHJ) memory device with a configuration of indium-doped tin oxide (ITO)/CH3NH3PbI3:PVK/Al has been successfully fabricated. Under a threshold voltage of -1.57 V, this device shows a nonvolatile write-once read-many-times (WORM) memory effect, with a maximum ON/OFF current ratio exceeding 10(3). In contrast, the ITO/CH3NH3PbI3/Al device showed only conductor characteristics, while the PVK-based device exhibited insulator behavior. Upon being subjected to voltages, an interesting filamentary nature of the CH3NH3PbI3:PVK film was also observed in situ at the microscopic nanometer level using a conductive atomic force microscopy (C-AFM) technique with a device configuration of Si/Pt/CH3NH3PbI3:PVK/Pt. The mechanism associated with the memory effect is discussed. The electric-field-induced intermolecular charge transfer effect between CH3NH3PbI3 and PVK, and the possible conformational ordering of the PVK side-chains/backbone under an applied bias voltage, may cause the electrical conductivity switching and WORM effect in the reported BHJ device. PMID:26645358

  5. Top-down prepared silicon nanocrystals and a conjugated polymer-based bulk heterojunction: Optoelectronic and photovoltaic applications

    International Nuclear Information System (INIS)

    Blends consisting of doped silicon nanocrystals (Si-ncs) and two conjugated polymers (poly(3-hexylthiophene) (P3HT) and poly(methoxy ethylexyloxy phenylenevinilene) (MEH PPV)) with improved photostability were fabricated. We show that a top-down approach by electrochemical etching is suitable for preparing doped (boron and phosphorus) freestanding and surfactant-free Si-ncs. The doping of Si-ncs was confirmed by low temperature photoluminescence and electron spin resonance analysis. It is demonstrated that such Si-ncs can be successfully used for the fabrication of room temperature photoluminescent and photosensitive blends. We argue that the luminescence and transport properties of the blends are controlled by the Si-ncs properties and could be assigned to quantum confinement of excitons in nanocrystalites with an energy band gap of ∼2 eV. Furthermore, the blending of doped Si-ncs in both conjugated polymers led to the establishment of a bulk heterojunction between the Si-ncs and polymer. The difference in electron affinity and ionization potential between nanocrystals and polymer dissociated the excitons. Those blends showed increased carrier transport and photoconductivity under ambient conditions. It was found that introduction of less defective p-type doped Si-ncs significantly improved overall photostability of the blend. The Si-ncs non-toxicity and easy integration into well-established silicon technologies might bring considerable benefit for hybrid optoelectronic and photovoltaic device development.

  6. 1,3,5-Tris(phenyl-2-benzimidazole)-benzene cathode buffer layer thickness dependence in solution-processable organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine

    Science.gov (United States)

    De Roméo Banoukepa, Gilles; Fujii, Akihiko; Shimizu, Yo; Ozaki, Masanori

    2015-04-01

    Studies on the insertion effects of a cathode buffer layer on bulk heterojunction organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM) by using 1,3,5-tris(phenyl-2-benzimidazole)-benzene (TPBi) as a cathode buffer layer material have been carried out. The external quantum efficiency and the short-circuit current markedly increased, resulting in the enhancement of the power conversion efficiency. The solar cell performance has been discussed from the atomic force microscopy, photoelectron yield spectroscopy and X-ray photoelectron spectroscopy measurements.

  7. Graphene composite for improvement in the conversion efficiency of flexible poly 3-hexyl-thiophene:[6,6]-phenyl C{sub 71} butyric acid methyl ester polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, A. K., E-mail: akchau@barc.gov.in, E-mail: akc.barc@gmail.com; Gusain, Abhay; Jha, P.; Koiry, S. P.; Saxena, Vibha; Veerender, P.; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India)

    2014-03-31

    The solution of thin graphene-sheets obtained from a simple ultrasonic exfoliation process was found to chemically interact with [6,6]-phenyl C{sub 71} butyric acid methyl ester (PCBM) molecules. The thinner graphene-sheets have significantly altered the positions of highest occupied molecular orbital and lowest unoccupied molecular orbital of PCBM, which is beneficial for the enhancement of the open circuit voltage of the solar cells. Flexible bulk heterojunction solar cells fabricated using poly 3-hexylthiophene (P3HT):PCBM-graphene exhibited a power conversion efficiency of 2.51%, which is a ∼2-fold increase as compared to those fabricated using P3HT:PCBM. Inclusion of graphene-sheets not only improved the open-circuit voltage but also enhanced the short-circuit current density owing to an improved electron transport.

  8. Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging.

    Science.gov (United States)

    Pedersen, E B L; Angmo, D; Dam, H F; Thydén, K T S; Andersen, T R; Skjønsfjell, E T B; Krebs, F C; Holler, M; Diaz, A; Guizar-Sicairos, M; Breiby, D W; Andreasen, J W

    2015-08-28

    Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced. PMID:26220159

  9. Side-chain Engineering of Benzo[1,2-b:4,5-b']dithiophene Core-structured Small Molecules for High-Performance Organic Solar Cells.

    Science.gov (United States)

    Yin, Xinxing; An, Qiaoshi; Yu, Jiangsheng; Guo, Fengning; Geng, Yongliang; Bian, Linyi; Xu, Zhongsheng; Zhou, Baojing; Xie, Linghai; Zhang, Fujun; Tang, Weihua

    2016-01-01

    Three novel small molecules have been developed by side-chain engineering on benzo[1,2-b:4,5-b']dithiophene (BDT) core. The typical acceptor-donor-acceptor (A-D-A) structure is adopted with 4,8-functionalized BDT moieties as core, dioctylterthiophene as π bridge and 3-ethylrhodanine as electron-withdrawing end group. Side-chain engineering on BDT core exhibits small but measurable effect on the optoelectronic properties of small molecules. Theoretical simulation and X-ray diffraction study reveal the subtle tuning of interchain distance between conjugated backbones has large effect on the charge transport and thus the photovoltaic performance of these molecules. Bulk-heterojunction solar cells fabricated with a configuration of ITO/PEDOT:PSS/SM:PC71BM/PFN/Al exhibit a highest power conversion efficiency (PCE) of 6.99% after solvent vapor annealing. PMID:27140224

  10. Side-chain Engineering of Benzo[1,2-b:4,5-b’]dithiophene Core-structured Small Molecules for High-Performance Organic Solar Cells

    Science.gov (United States)

    Yin, Xinxing; An, Qiaoshi; Yu, Jiangsheng; Guo, Fengning; Geng, Yongliang; Bian, Linyi; Xu, Zhongsheng; Zhou, Baojing; Xie, Linghai; Zhang, Fujun; Tang, Weihua

    2016-05-01

    Three novel small molecules have been developed by side-chain engineering on benzo[1,2-b:4,5-b’]dithiophene (BDT) core. The typical acceptor-donor-acceptor (A-D-A) structure is adopted with 4,8-functionalized BDT moieties as core, dioctylterthiophene as π bridge and 3-ethylrhodanine as electron-withdrawing end group. Side-chain engineering on BDT core exhibits small but measurable effect on the optoelectronic properties of small molecules. Theoretical simulation and X-ray diffraction study reveal the subtle tuning of interchain distance between conjugated backbones has large effect on the charge transport and thus the photovoltaic performance of these molecules. Bulk-heterojunction solar cells fabricated with a configuration of ITO/PEDOT:PSS/SM:PC71BM/PFN/Al exhibit a highest power conversion efficiency (PCE) of 6.99% after solvent vapor annealing.

  11. Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

    Science.gov (United States)

    Adachi, Chihaya

    2016-01-01

    Summary Solution-processable star-shaped and linear π-conjugated oligomers consisting of an electron-donating tetrathienoanthracene (TTA) core and electron-accepting diketopyrrolopyrrole (DPP) arms, namely, TTA-DPP4 and TTA-DPP2, were designed and synthesized. Based on density functional theory calculations, the star-shaped TTA-DPP4 has a larger oscillator strength than the linear TTA-DPP2, and consequently, better photoabsorption property over a wide range of visible wavelengths. The photovoltaic properties of organic solar cells based on TTA-DPP4 and TTA-DPP2 with a fullerene derivative were evaluated by varying the thickness of the bulk heterojunction active layer. As a result of the enhanced visible absorption properties of the star-shaped π-conjugated structure, better photovoltaic performances were obtained with relatively thin active layers (40–60 nm).

  12. Effects of thermal-annealing and processing-additive treatment on crystallization-induced phase separation in organic solar cells utilizing octapentyl tetrabenzotriazaporphyrins

    International Nuclear Information System (INIS)

    Effects of thermal-annealing and processing-additive treatment on crystallization-induced phase separation and photovoltaic performance in bulk heterojunction (BHJ) organic solar cells utilizing non-peripherally substituted octapentyl tetrabenzotriazaporphyrin (C5TBTAPH2) mixed in 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C71 ([70]PCBM) were reported. By using either thermal-annealing or processing-additive treatment, the C5TBTAPH2-crystallite sizes in the BHJ films were enlarged and the power conversion efficiencies (PCEs) were increased due to improvement of the crystallization-induced phase separation. However, the optimum PCEs (4.2%) of the processing-additive treated devices were markedly higher than those PCEs (1.4%) of devices treated by thermal annealing. These results were discussed by taking the thermal properties and molecular aggregation of [70]PCBM into consideration. (paper)

  13. A comparative study of fluorine substituents for enhanced stability of flexible and ITO-free high-performance polymer solar cells

    DEFF Research Database (Denmark)

    Carlé, Jon Eggert; Helgesen, Martin; Zawacka, Natalia Klaudia;

    2014-01-01

    Two low-band gap polymer series based on benzo[1,2-b:4,5-b?]dithiophene (BDT) and dithienylbenzothiadiazole, with different numbers of fluorine substituents on the 2,3,1-benzothiadiazole unit, have been synthesized and explored in a comparative study of the photochemical stability and operational...... lifetime in flexible large area roll-coated bulk heterojunction solar cells. The two polymer series have different side chains on the BDT unit, namely 2-hexyldecyloxy (BDTHDO) (P1-P3) or 2-hexyldecylthiophene (BDT THD) (P4-P6). The photochemical stability clearly shows that the stability enhances along...... series showed the best performance, reaching efficiencies up to 3.8% for an active area of 1 cm2, due to an enhanced current compared to P1-P3. Lifetime measurements, carried out according to international summit on OPV stability (ISOS), of encapsulated devices reveals an initial fast decay for P1-P6 in...

  14. Charge Recombination, Transport Dynamics, and Interfacial Effects in Organic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Heeger, Alan; Bazan, Guillermo; Nguyen, Thuc-Quyen; Wudl, Fred

    2015-02-27

    The need for renewable sources of energy is well known. Conversion of sunlight to electricity using solar cells is one of the most important opportunities for creating renewable energy sources. The research carried out under DE-FG02-08ER46535 focused on the science and technology of “Plastic” solar cells comprised of organic (i.e. carbon based) semiconductors. The Bulk Heterojunction concept involves a phase separated blend of two organic semiconductors each with dimensions in the nano-meter length scale --- one a material that functions as a donor for electrons and the other a material that functions as an acceptor for electrons. The nano-scale inter-penetrating network concept for “Plastic” solar cells was created at UC Santa Barbara. A simple measure of the impact of this concept can be obtained from a Google search which gives 244,000 “hits” for the Bulk Heterojunction solar cell. Research funded through this program focused on four major areas: 1. Interfacial effects in organic photovoltaics, 2. Charge transfer and photogeneration of mobile charge carriers in organic photovoltaics, 3. Transport and recombination of the photogenerated charge carriers in organic photovoltaics, 4. Synthesis of novel organic semiconducting polymers and semiconducting small molecules, including conjugated polyelectrolytes. Following the discovery of ultrafast charge transfer at UC Santa Barbara in 1992, the nano-organic (Bulk Heterojunction) concept was formulated. The need for a morphology comprising two interpenetrating bicontinuous networks was clear: one network to carry the photogenerated electrons (negative charge) to the cathode and one network to carry the photo-generated holes (positive charge) to the anode. This remarkable self-assembled network morphology has now been established using Transmission electron Microscopy (TEM) either in the Phase Contrast mode or via TEM-Tomography. The steps involved in delivering power from a solar cell to an external circuit

  15. Effect of Fluorine Substitution on the Charge Carrier Dynamics of Benzothiadiazole-Based Solar Cell Materials.

    Science.gov (United States)

    Kim, In-Sik; Kim, In-Bok; Kim, Dong-Yu; Kwon, Seong-Hoon; Ko, Do-Kyeong

    2016-08-01

    The femtosecond transient absorption (TA) characterization of a new benzothiadiazole (BT)-based donor-acceptor conjugated copolymer, poly[(2,6-dithieno[3,2-b:2',3'-d]thiophene)-alt-(4,7-di(4-octyldodecylthiopen-2-yl)-2,1,3-benzo[c][1,2,5]thiadiazole (PBT), as well as its fluorinated derivatives, PFBT and PDFBT, is carried out. Additionally, bulk heterojunction (BHJ) films consisting of the copolymers and [6,6]-phenyl-C71 -butylic acid methyl ester (PC70 BM) are examined using TA spectroscopy. Both the singlet excited state dynamics in the copolymers and the charge transfer state dynamics in the BHJs are investigated in terms of fluorination dependency; the fluorinated copolymers exhibit less singlet exciton recombination rate than the fluorine-free copolymer, and the BHJs including the fluorinated copolymers display slower monomolecular recombination than the fluorine-free analogue. Furthermore, the excitation-intensity-dependent TA dynamics of the copolymers and BHJs is investigated, revealing that, when sufficiently high excitation intensity is used to induce annihilation processes, the fluorinated copolymers and BHJs incorporating the fluorinated copolymers show more rapid TA decay ascribable to morphological enhancement. These TA spectroscopic findings are found to correlate with the device characteristics with respect to fluorinated content in the polymer solar cells. In particular, both the short-circuit current density and fill factor of BHJ solar cells correspond closely with the fast decay parameters of the BHJ films under high excitation intensity. PMID:27226245

  16. Pad printing as a film forming technique for polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Frederik C. [Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark)

    2009-04-15

    Pad printing as a technique for preparing the active layer in polymer solar cells is presented. The technique employs a silicone rubber stamp to pick up the motif from a gravure plate and transfer it to the substrate. The strengths and limitations of pad printing are discussed and polymer solar cells prepared by pad printing are presented. Devices were prepared on indium tin oxide substrates but in principle the entire photovoltaic device comprising front and back electrodes, barrier layers and active layer could be printed with no need for vacuum steps. The device geometry comprises a spin coated transparent zinc oxide front electrode, a pad printed active layer based on a bulk heterojunction of the thermocleavable polymer poly(3-(2-methylhexyloxycarbonyl)thiophene-co-thiopene) (P3MHOCT) and zinc oxide nanoparticles, spin coated PEDOT:PSS and finally a manually cast thermally cured silver paste back electrode. The P3MHOCT was converted to poly(3-carboxy-dithiophene) (P3CT) in situ by heating the film to 200 C for a brief period. The entire printing and device preparation was carried out in the ambient atmosphere and the devices obtained had a good stability in air during storage and operation. (author)

  17. Reducing burn-in voltage loss in polymer solar cells by increasing the polymer crystallinity

    KAUST Repository

    Heumueller, Thomas

    2014-08-01

    In order to commercialize polymer solar cells, the fast initial performance losses present in many high efficiency materials will have to be managed. This burn-in degradation is caused by light-induced traps and its characteristics depend on which polymer is used. We show that the light-induced traps are in the bulk of the active layer and we find a direct correlation between their presence and the open-circuit voltage loss in devices made with amorphous polymers. Solar cells made with crystalline polymers do not show characteristic open circuit voltage losses, even though light-induced traps are also present in these devices. This indicates that crystalline materials are more resistant against the influence of traps on device performance. Recent work on crystalline materials has shown there is an energetic driving force for charge carriers to leave amorphous, mixed regions of bulk heterojunctions, and charges are dominantly transported in pure, ordered phases. This energetic landscape allows efficient charge generation as well as extraction and also may benefit the stability against light-induced traps. This journal is © the Partner Organisations 2014.

  18. Physical and electrical models for interpreting AC and DC transport measurements in polymer solar cells

    Science.gov (United States)

    McIntyre, Max; Tzolov, Marian; Cossel, Raquel; Peeler, Seth

    We have fabricated and studied bulk heterojunction solar cells using a mixture of the low bandgap material PCPDTBT and PCBM-C60. Our transport studies show that the devices in dark have good rectification and they respond to AC voltage as a simple RC circuit. The illumination causes an additional contribution to the impedance, which varies with the level of illumination. One proposed model is that photo-generated charges can become trapped in potential wells. These charges then follow a Debye relaxation process, which contributes to a varying dielectric constant. Another proposed model is based on a RC circuit model with two capacitors which can describe the varying capacitance behavior. The physical mechanism for this model is that photo-generated charges become accumulated at the interface between PCPDTBT and PCBM-C60 and form an additional layer of charge. We will show that our circuit models and their analogous physical models can predict the AC and DC responses of polymer solar cells.

  19. Optical and electrical effects of plasmonic nanoparticles in high-efficiency hybrid solar cells.

    Science.gov (United States)

    Fu, Wei-Fei; Chen, Xiaoqiang; Yang, Xi; Wang, Ling; Shi, Ye; Shi, Minmin; Li, Han-Ying; Jen, Alex K-Y; Chen, Jun-Wu; Cao, Yong; Chen, Hong-Zheng

    2013-10-28

    Plasmonics have been proven to be an effective way to harness more incident light to achieve high efficiency in photovoltaic devices. Herein, we explore the possibility that plasmonics can be utilized to enhance light trapping and power conversion efficiency (PCE) for polymer-quantum dot (QD) hybrid solar cells (HSCs). Based on a 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) and a CdSe QD bulk-heterojunction (BHJ) system, gold nanoparticles were doped at different locations of the devices. Successfully, an improved PCE of 3.20 ± 0.22% and 3.16 ± 0.15% was achieved by doping the hole transporting layer and the active layer, respectively, which are among the highest values reported for CdSe QD based HSCs. A detailed study of processing, characterization, microscopy, and device fabrication is conducted to understand the underlying mechanism for the enhanced device performance. The success of this work provides a simple and generally applicable approach to enhance light harnessing of polymer-QD hybrid solar cells. PMID:24006000

  20. Numerical simulations of the role of a ferroelectric polymer interfacial layer in organic solar cells.

    Science.gov (United States)

    Liu, Bo; Xu, Feng; Zhang, Xinghua; Yan, Dadong; Lu, Dan

    2016-02-21

    A Pauli master equation method is adopted for the simulation of polymer bulk heterojunction (BHJ) solar cells with vinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) films as interfacial layers. According to previous reports, using highly crystalline P(VDF-TrFE) films as interfacial layers can highly enhance the efficiency of polymer BHJ solar cells, and possible mechanisms for the enhancement by two different groups were given as the dipole induced permanent internal electric field or simply the electrode improvement which implied that the origin is the barrier lowering effect. The correlation between the appearance of S-shaped current density-voltage (J-V) characteristics and the energy barrier is studied first, and then further results indicate that the previous electrode improvement model provides a consistent explanation for the origin of performance enhancement due to the insertion of polarized P(VDF-TrFE) interfacial layers. Moreover, the phenomenon of an increase of the internal electric field observed before can be attributed to better contact conditions which help reduce the bimolecular recombination rate. Comparatively speaking, the electrode improvement model can give a more rational explanation for the origin of performance enhancement experimentally found. In contrast, the dipole induced permanent internal electric field model was not complete enough. PMID:26822850

  1. Improving performance of inverted organic solar cells using ZTO nanoparticles as cathode buffer layer

    Science.gov (United States)

    Tsai, Meng-Yen; Cheng, Wen-Hui; Jeng, Jiann-Shing; Chen, Jen-Sue

    2016-06-01

    In this study, a low-temperature solution-processed zinc tin oxide (ZTO) films are successfully utilized as the cathode buffer layer in the inverted organic P3HT:PCBM bulk heterojunction solar cells. ZTO film cathode buffer layer with an appropriate Sn-doping concentration outperforms the zinc oxide (ZnO) film with an improved power conversion efficiency (1.96% (ZTO film) vs. 1.56% (ZnO film)). Furthermore, ZTO nanoparticles (NPs) are also synthesized via low-temperature solution route and the device with ZTO NPs buffer layer exhibits a significant improvement in device performance to reach a PCE of 2.60%. The crystallinity of the cathode buffer layer plays an influential factor in the performance. From impedance spectroscopy analysis, a correlation between short circuit current (Jsc), carrier life time (τavg) and, thus, PCE is observed. The interplay between composition and crystallinity of the cathode buffer layers is discussed to find their influences on the solar cell performance.

  2. Introduction to solar cell production

    International Nuclear Information System (INIS)

    This book introduces solar cell production. It is made up eight chapters, which are summary of solar cell with structure and prospect of the business, special variable of solar cell on light of the sun and factor causing variable of solar cell, production of solar cell with surface texturing, diffusion, metal printing dry and firing and edge isolation, process of solar cell on silicone wafer for solar cell, forming of electrodes, introduction of thin film solar cell on operating of solar cell, process of production and high efficiency of thin film solar cell, sorting of solar cell and production with background of silicone solar cell and thin film solar cell, structure and production of thin film solar cell and compound solar cell, introduction of solar cell module and the Industrial condition and prospect of solar cell.

  3. 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.

  4. Organic-inorganic hybrid nanostructures for solar cell applications

    Science.gov (United States)

    AbdulAlmohsin, Samir M.

    with large surface area and ideal corrosion-inertness toward polysulfide redox exhibit promising application potential as a counter electrode for NCSSCs. This study demonstrates that the solution grown CdS nanocrystals and polyaniline are potentially useful for fabricating high performance NCSSCs, which is technically attractive for large scale and economic production. A hybrid structure containing graphene-enriched poly (3-hexylthiophene) (G-P3HT) or poly (3-hexylthiophene):(6, 6)-phenyl C60 butyric acid methyl esterand tetra (4-carboxyphenyle) porphyrin-grafted ZnO nanowire arrays was investigated for nanowire/polymer hybrid solar cells. The vertically aligned nanowires embedded in the organic films act as an active n-type semiconductor and a high-efficiency charge collection electrode. The grafting surface of ZnO nanowires by porphyrin was found to significantly improve the cell efficiency as compared with those using pristine ZnO nanowires. The improvement is attributed to the enhanced light harvesting and charge injection with the presence of porphyrin at the junction interface. A comparison study showed that the use of G-P3HT further increase the efficiency of the nanowire solar cells from 0.09 to 0.4%, benefiting from the improved hole collection with graphene in the polymer. This study indicates that hybrid structure comprising surface modified, vertically aligned ZnO nanowire arrays embedded in G-P3HT is promising for solar cell applications. A combination of bulk heterojunction of P3HT: PCBM with ZnO nanorod arrays was also studied for solar cell applications. In the P3HT: PCBM devices, electron donors such as poly (3-hexythiophene) (P3HT) and acceptors as (6, 6)-phenyl C61 butyric acid methyl ester (PCBM) are blended to form one mixed layer (a bulk heterojunction). The charge separation of photo-induced excitons is greatly enhanced by ultra-fast electron transfer and large interface between the two components. However, the charge collection is one of the

  5. Improvements of fill factor in solar cells based on blends of polyfluorene copolymers as electron donors

    International Nuclear Information System (INIS)

    The photovoltaic characteristics of solar cells based on alternating polyfluorene copolymers, poly(2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3' -benzothia diazole)) (APFO-3), and poly(2,7-(9,9-didodecyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3' -benzothiadiazole)) (APFO-4), blended with an electron acceptor fullerene molecule [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been investigated and compared. The two copolymers have the same aromatic backbone structure but differ by the length of their alkyl side chain. The overall photovoltaic performance of the solar cells is comparable irrespective of the copolymer used in the active layer. However, the fill factor (FF) values of the devices are strongly affected by the copolymer type. Higher FF values were realized in solar cells with APFO-4 (with longer alkyl side chain)/PCBM bulk heterojunction active layer. On the other hand, devices with blends of APFO-3/APFO-4/PCBM were found to render fill factor values that are intermediate between the values obtained in solar cells with APFO-3/PCBM and APFO-4/PCBM active film. Upon using APFO-3/APFO-4 blends as electron donors, the cell efficiency can be enhanced by about 16% as compared to cells with either APFO-3 or APFO-4. The transport of holes in each polymer obeys the model of hopping transport in disordered media. However, the degree of energetic barrier against hopping was found to be larger in APFO-3. The tuning of the photovoltaic parameters will be discussed based on studies of hole transport in the pure polymer films, and morphology of blend layers. The effect of bipolar transport in PCBM will also be discussed

  6. PEROVSKITE SOLAR CELLS (REVIEW ARTICLE)

    OpenAIRE

    Benli, Deniz Ahmet

    2015-01-01

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

  7. Quantitative characterization of phase separation in the photoactive layer of polymer solar cells by the phase image of atomic force microscopy

    International Nuclear Information System (INIS)

    We have quantitatively characterized the phase separation of poly(3-hexylthiophene) (P3HT):C61-butyric acid methyl ester (PCBM) blend films and studied the effect of phase separation of photoactive layer on the performance of polymer solar cells. A mixed solvent of dichlorobenzene and chlorobenzene was adopted to prepare the P3HT:PCBM blend films, and a series of blend films with different morphologies were obtained by adjusting both the volume ratio of dichlorobenzene to chlorobenzene and the solvent annealing time. The surface morphology and phase distribution were measured by atomic force microscopy (AFM). The interface length between the domains of donor and acceptor, which is extracted from the AFM phase image of blend film, was used to quantitatively characterize the phase separation of photoactive layer. It was found that the short-circuit current density (JSC) of bulk heterojunction solar cells is proportional to the interfacial area of two phases, while it has a negligible effect on the open-circuit voltage. These results indicate that the larger interfacial area of donor and acceptor phases is beneficial to the exciton dissociation and carrier transport resulting in a significant increase of JSC and power conversion efficiency. - Highlights: • Phase separation of photoactive layers in polymer solar cells was evaluated quantitatively. • Interface contours between the donor and acceptor were extracted from AFM phase images. • Effects of phase separation on polymer solar cell performance were investigated. • The interface area mainly influences short-circuit current of the polymer solar cells

  8. Highly efficient organic solar Cells based on a robust room-temperature solution-processed copper iodide hole transporter

    KAUST Repository

    Zhao, Kui

    2015-07-30

    Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole–transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200 °C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in an inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, are also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films.

  9. The effect of functionalized single walled carbon nanotube with octadecylamine on efficiency of poly-(3-hexylthiophene): [(6,6)] phenyl C61 butyric acid methyl ester organic solar cells

    International Nuclear Information System (INIS)

    We fabricated bulk heterojunction (BHJ) solar cells with a configuration ITO/PEDOT:PSS/P3HT:PCBM:o-SWNT/Al that consisted of different carbon nanotubes concentrations functionalized with octadecylamine (o-SWNT). The three solar cells which consisted of o-SWNT concentrations of 0.01%, 0.001% and 0.0001% by weight were prepared at the same process conditions. The absorption measurements of active layer (P3HT:PCBM: x wt% of o-SWNT) and current–voltage measurements of solar cells have shown that VOC does not change depending on the used contribution rates. However, JSC has increased by 23.8% in solar cells that are fabricated with o-SWNT concentrations of 0.001 wt% compared with solar cell without o-SWNT. The power conversion efficiency has also increased by 31.8%. While IPCE is about 37% in 350 nm in the reference solar cell, IPCE of the solar cell comprised of o-SWNT of 0.001 wt% is about 45%

  10. Solar cell concentrating system

    International Nuclear Information System (INIS)

    This study reviews fabrication techniques and testing facilities for different solar cells under concentration which have been developed and tested. It is also aimed to examine solar energy concentrators which are prospective candidates for photovoltaic concentrator systems. This may provide an impetus to the scientists working in the area of solar cell technology

  11. Impact of Molecular Orientation and Spontaneous Interfacial Mixing on the Performance of Organic Solar Cells

    KAUST Repository

    Ngongang Ndjawa, Guy O.

    2015-07-28

    A critically important question that must be answered to understand how organic solar cells operate and should be improved is how the orientation of the donor and acceptor molecules at the interface influences exciton diffusion, exciton dissociation by electron transfer and recombination. It is exceedingly difficult to probe the orientation in bulk heterojunctions because there are many interfaces and they are arranged with varying angles with respect to the substrate. One of the best ways to study the interface is to make bilayer solar cells with just one donor-acceptor interface. Zinc phthalocyanine is particularly interesting to study because its orientation can be adjusted by using a 2-nm-thick copper iodide seed layer before it is deposited. Previous studies have claimed that solar cells in which fullerene acceptor molecules touch the face of zinc phthalocyanine have more current than ones in which the fullerenes touch the edge of zinc phthalocyanine because of suppressed recombination. We have more thoroughly characterized the system using in situ x-ray photoelectron spectroscopy and found that the interfaces are not as sharp as previous studies claimed when formed at room temperature or above. Fullerenes have a much stronger tendency to mix into the face-on films than into the edge-on films. Moreover we show that almost all of the increase in the current with face-on films can be attributed to improved exciton diffusion and to the formation of a spontaneously mixed interface, not suppressed recombination. This work highlights the importance of spontaneous interfacial molecular mixing in organic solar cells, the extent of which depends on molecular orientation of frontier molecules in donor domains.

  12. Photovoltaic solar cell

    Science.gov (United States)

    Nielson, Gregory N.; Gupta, Vipin P.; Okandan, Murat; Watts, Michael R.

    2015-09-08

    A photovoltaic solar concentrator is disclosed with one or more transverse-junction solar cells (also termed point contact solar cells) and a lens located above each solar cell to concentrate sunlight onto the solar cell to generate electricity. Piezoelectric actuators tilt or translate each lens to track the sun using a feedback-control circuit which senses the electricity generated by one or more of the solar cells. The piezoelectric actuators can be coupled through a displacement-multiplier linkage to provide an increased range of movement of each lens. Each lens in the solar concentrator can be supported on a frame (also termed a tilt plate) having three legs, with the movement of the legs being controlled by the piezoelectric actuators.

  13. The effect of methanol treatment on the performance of polymer solar cells

    International Nuclear Information System (INIS)

    Significant performance enhancement was observed for the bulk-heterojunction polymer solar cell of ITO/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly[N-9″-heptadecanyl-2,7-carbazole-alt-5,5-(4′, 7′-di-2-thienyl-2′,1′,3′ -benzodithiazole)]:[6,6]-phenyl C71 butyric acid methyl ester (PCDTBT:PC71BM)/Al when the as-cast active layer was rinsed with methanol before the deposition of the metal electrode. Comparison of independent anode interfacial layers of PEDOT:PSS and MoO3 indicated that the effects of methanol treatment on the improvement of device performance are more pronounced for PEDOT:PSS-based devices. No discernible changes can be observed in film thickness, surface topography and UV–vis absorption profiles of the photoactive layer, indicating the absence of film reconstruction and the improvement of device performance are hence attributed to the modification of the interface between the PEDOT:PSS and the fresh active layer. Further examination of the devices containing a cathode interlayer of poly[(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)] (PFN) also demonstrates the potential modification of the interface between the PEDOT:PSS and the active layer by methanol in addition to the widely observed PFN functionality. (paper)

  14. Solution-processed nickel compound as hole collection layer for efficient polymer solar cells

    International Nuclear Information System (INIS)

    We demonstrated efficient bulk heterojunction polymer solar cells (PSCs) by inserting a solution-processable hole collection layer (HCL) between the indium tin oxide (ITO) electrode and photoactive layer. The HCL was prepared by spin-coating nickel acetylacetonate (Ni(acac)2) isopropanol solution on ITO, and then baking in air at 180 °C for 10 min followed by UV ozone treatment, which was marked as a-Ni(acac)2. The a-Ni(acac)2 HCL shows suitable energy levels, high hole mobility of 4.09  ×  10−3 cm2 V−1·s−1, and high transparency with light transmittance better than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) in the wavelength range 550–800 nm. The PSCs with a-Ni(acac)2 HCL showed improved performance compared with the PSCs without or with traditional PEDOT:PSS HCL. The power conversion efficiency of the PSC based on PBDTTT-C-T:PC70BM with a-Ni(acac)2 HCL reached 7.84% under the illumination of AM 1.5 G, 100 mW cm−2. (paper)

  15. Pushing structural limits to reveal fundamental mechanisms of organic solar cell operation

    Science.gov (United States)

    Rand, Barry

    2015-03-01

    Organic-based solar cells are beginning to emerge with the potential to compete with other thin film photovoltaic technologies, with efficiencies of 12% recently demonstrated. Unique to the function of organic photovoltaics are the creation of tightly bound excitons that can only be efficiently separated at a donor/acceptor (D/A) interface capable of providing the necessary energetic driving force for dissociation. The consequences of this are the need for long exciton diffusion lengths and the presence of charge transfer (CT) states, ground state complexes that exist at the D/A interface. We have found that charge transfer states are more easily separated into free charge if they are delocalized; an aspect that becomes most feasible for highly ordered systems. I will discuss our recent efforts to template and control film morphology and molecular orientation. These studies allow us to understand the importance of molecular orientation, crystallite size, and crystal phase. We will show templated devices utilizing neat films as well as bulk heterojunctions, with crystallite dimensions spanning from the more standard nano-sized grains to those with highly ordered micron-sized crystalline domains revealing unprecedented thin film exciton diffusion lengths of 100s of nm. In these highly ordered films, owing to significant delocalization, we are able to directly measure photocurrent from multiple CT states, an aspect which has important consequences for the design of more efficient photocurrent generation. We acknowledge support from DOE BES Grant #11493344.

  16. Charge transport and recombination in P3HT:PbS solar cells

    International Nuclear Information System (INIS)

    The charge carrier transport in thin film hybrid solar cells is analyzed and correlated with device performance and the mechanisms responsible for recombination loss. The hybrid bulk heterojunction consisted of a blend of poly(3-hexylthiophene) (P3HT) and small size (2.4 nm) PbS quantum dots (QDs). The charge transport in the P3HT:PbS blends was determined by measuring the space-charge limited current in hole-only and electron-only devices. When the loading of PbS QDs exceeds the percolation threshold, a significant increase of the electron mobility is observed in the blend with PbS QDs. The hole mobility, on the other hand, only slightly decreased upon increasing the loading of PbS QDs. We also showed that the photocurrent is limited by the low shunt resistance rather than by space-charge effects. The significant reduction of the fill factor at high light intensity suggests that under these conditions the non-geminate recombination dominates. However, at open-circuit conditions, the trap-assisted recombination dominates over non-geminate recombination

  17. Transient Photocurrent Response of Plasmon-Enhanced Polymer Solar Cells with Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yi Fang

    2015-07-01

    Full Text Available In this work, the transient photocurrent of the plasmon-enhanced polymer bulk heterojunction solar cells based on poly(3-hexylthiophene (P3HT and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM is investigated. Two kinds of localized surface plasmon resonance (LSPR enhanced devices were fabricated by doping the gold nanoparticles (Au NPs into the anode buffer layer and inserting Au NPs between the anode buffer layer and the active layer. We probed the dynamics of the turn-on and turn-off responses to 400 μs square-pulse optical excitation from the 380 nm and 520 nm light-emitting diodes (LED driven by an electric pulse generator. The transient photocurrent curves of devices with Au NPs at different positions and under different excitation wavelength are compared and analyzed. The charge trapping/detrapping processes that occurred at the interface of Au NPs and the active layer were observed; these exhibit an overshoot in the initial fast rise of photocurrent response. Our results show that the incorporating position of Au NPs is an important key factor to influence the transient photocurrent behaviors.

  18. Morphology Evolution of Molecular Weight Dependent P3HT: PCBM Solar Cells

    Science.gov (United States)

    Liu, Feng; Chen, Dian; Briseno, Alejandro; Russell, Thomas

    2011-03-01

    Effective strategies to maximize the performance of bulk heterojunction (BHJ) photovoltaic devices have to be developed and understood to realize their full potential. In BHJ solar cells, the morphology of the active layer is a critical issue to improve device efficiency. In this work, we choose poly(3-hexyl-thiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) system to study the morphology evolution. Different molecular weight P3HTs were synthesized by using Grignard Metathesis (GRIM)~method. In device optimization, polymer with a molecular weight between 20k-30k shows the highest efficiency. It was observed that the as-spun P3HT: PCBM (1:1) blends do not have high order by GISAXS. Within a few seconds of thermal annealing at 150& circ; the crystallinity of P3HT increaased substantially and the polymer chains adopted an edge-on orientation. An-bicontinous morphology was also developed within this short thermal treatment. The in situ GISAXS experiment showed that P3HT of high molecular weight was more easily crystallized from a slowly evaporated chlorobenzene solution and their edge-on orientation is much more obvious than for the lower molecular weight P3HTs. DSC was used to study the thermal properties of P3HTs and P3HT: PCBM blend. The χ of P3HT-PCBM was also calculated by using melting point depression method.

  19. Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells with Good Mechanical Stability.

    Science.gov (United States)

    Kim, Wanjung; Kim, Soyeon; Kang, Iljoong; Jung, Myung Sun; Kim, Sung June; Kim, Jung Kyu; Cho, Sung Min; Kim, Jung-Hyun; Park, Jong Hyeok

    2016-05-10

    Herein, we report a tailored Ag mesh electrode coated with poly(3,4-ethylenedioxythiophene) (PEDOT) polymer on a flexible polyethylene terephthalate (PET) substrate. The introduction of this highly conductive polymer solves the existing problems of Ag mesh-type transparent conductive electrodes, such as high pitch, roughness, current inhomogeneity, and adhesion problems between the Ag mesh grid and PEDOT polymer or PET substrate, to result in excellent electron spreading from the discrete Ag mesh onto the entire surface without sacrificing sheet conductivity and optical transparency. Based on this hybrid anode, we demonstrate highly efficient flexible polymer solar cells (PSCs) with a high fill factor of 67.11 %, which results in a power conversion efficiency (PCE) of 6.9 % based on a poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl}):[6,6]-phenyl-C71 -butyric acid methyl ester bulk heterojunction device. Furthermore, the PSC device with the Ag mesh electrode also exhibits a good mechanical bending stability, as indicated by a 70 % retention of the initial PCE after 500 bending cycles compared with the PSC device with a PET/indium tin oxide electrode, which retained 0 % of the initial PCE after 300 bending cycles. PMID:27038288

  20. π-Bridge-Independent 2-(Benzo[c][1,2,5]thiadiazol-4-ylmethylene)malononitrile-Substituted Nonfullerene Acceptors for Efficient Solar Cells

    KAUST Repository

    Wang, Kai

    2016-02-25

    Molecular acceptors are promising alternatives to fullerenes (e.g. PC61/71BM) in the fabrication of high-efficiency bulk-heterojunction (BHJ) solar cells. While solution-processed polymer-fullerene BHJ devices have recently met the 10% efficiency threshold, molecular acceptors have yet to prove comparably efficient with polymer donors. At this point in time, it is important to forge a better understanding of the design parameters that directly impact small-molecule (SM) acceptor performance in BHJ solar cells. In this report, we show that 2-(benzo[c][1,2,5]thiadiazol-4-ylmethylene)malononitrile (BM)-terminated SM acceptors can achieve efficiencies as high as 5.3% in BHJ solar cells with the polymer donor PCE10. Through systematic device optimization and characterization studies, we find that the nonfull-erene analogues (FBM, CBM and CDTBM) all perform comparably well, independent of the molecular structure and electronics of the π-bridge that links the two electron-deficient BM end groups. With estimated electron affinities within range of those of common fullerenes (4.0-4.3 eV), and a wider range of ionization potentials (6.2-5.6 eV), the SM acceptors absorb in the visible spectrum and effectively contribute to the BHJ device photocurrent. BM-substituted SM acceptors are promising alterna-tives to fullerenes in solution-processed BHJ solar cells.

  1. High-Performance Solution-Processed Non-Fullerene Organic Solar Cells Based on Selenophene-Containing Perylene Bisimide Acceptor.

    Science.gov (United States)

    Meng, Dong; Sun, Dan; Zhong, Chengmei; Liu, Tao; Fan, Bingbing; Huo, Lijun; Li, Yan; Jiang, Wei; Choi, Hyosung; Kim, Taehyo; Kim, Jin Young; Sun, Yanming; Wang, Zhaohui; Heeger, Alan J

    2016-01-13

    Non-fullerene acceptors have recently attracted tremendous interest because of their potential as alternatives to fullerene derivatives in bulk heterojunction organic solar cells. However, the power conversion efficiencies (PCEs) have lagged far behind those of the polymer/fullerene system, mainly because of the low fill factor (FF) and photocurrent. Here we report a novel perylene bisimide (PBI) acceptor, SdiPBI-Se, in which selenium atoms were introduced into the perylene core. With a well-established wide-band-gap polymer (PDBT-T1) as the donor, a high efficiency of 8.4% with an unprecedented high FF of 70.2% is achieved for solution-processed non-fullerene organic solar cells. Efficient photon absorption, high and balanced charge carrier mobility, and ultrafast charge generation processes in PDBT-T1:SdiPBI-Se films account for the high photovoltaic performance. Our results suggest that non-fullerene acceptors have enormous potential to rival or even surpass the performance of their fullerene counterparts. PMID:26652276

  2. Roll-coating fabrication of flexible large area small molecule solar cells with power conversion efficiency exceeding 1%

    DEFF Research Database (Denmark)

    Liu, Wenqing; Liu, Shiyong; Zawacka, Natalia Klaudia;

    2014-01-01

    All solution-processed flexible large area small molecule bulk heterojunction solar cells were fabricated via roll-coating technology. Our devices were produced from slot-die coating on a lab-scale mini roll-coater under ambient conditions without the use of spin-coating or vacuum evaporation...... methods. Four diketopyrrolopyrrole based small molecules (SMs 1-4) were utilized as electron donors with (6,6)phenyl- C61-butyric acid methyl ester as an acceptor and their photovoltaic performances based on roll-coated devices were investigated. The best power conversion efficiency (PCE) of 1.......01%, combined with an open circuit voltage of 0.73 V, a short-circuit current density of 3.13 mA cm (2) and a fill factor of 44% were obtained for the device with SM1, which was the first example reported for efficient roll-coating fabrication of flexible large area small molecule solar cells with PCE exceeding...

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

    International Nuclear Information System (INIS)

    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

  4. 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.

  5. Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Dong; Xu Xu-Rong; Zhao Su-Ling; Xu Zheng; Zhang Fu-Jun; Zhang Tian-Hui; Gong Wei; Yan Guang; Kong Chao; Wang Yong-Sheng

    2011-01-01

    In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in scries resistance (Rs), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.

  6. Solution-Processed Organic Solar Cells with Power Conversion Efficiencies of 2.5% using Benzothiadiazole/Imide-Based Acceptors

    KAUST Repository

    Bloking, Jason T.

    2011-12-27

    A new series of electron-deficient molecules based on a central benzothiadiazole moiety flanked with vinylimides has been synthesized via Heck chemistry and used in solution-processed organic photovoltaics (OPV). Two new compounds, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (PI-BT) and 4,7-bis(4-(N-hexyl-naphthalimide)vinyl)benzo[c]1,2,5-thiadiazole (NI-BT), show significantly different behaviors in bulk heterojunction (BHJ) solar cells using poly(3-hexylthiophene) (P3HT) as the electron donor. Two-dimensional grazing incidence X-ray scattering (2D GIXS) experiments demonstrate that PI-BT shows significant crystallization in spin-coated thin films, whereas NI-BT does not. Density functional theory (DFT) calculations predict that while PI-BT maintains a planar structure in the ground state, steric interactions cause a twist in the NI-BT molecule, likely preventing significant crystallization. In BHJ solar cells with P3HT as donor, PI-BT devices achieved a large open-circuit voltage of 0.96 V and a maximum device power-conversion efficiency of 2.54%, whereas NI-BT containing devices only achieved 0.1% power-conversion efficiency. © 2011 American Chemical Society.

  7. A quantum-chemical perspective into low optical-gap polymers for highly-efficient organic solar cells

    KAUST Repository

    Risko, Chad

    2011-03-15

    The recent and rapid enhancement in power conversion efficiencies of organic-based, bulk heterojunction solar cells has been a consequence of both improved materials design and better understanding of the underlying physical processes involved in photocurrent generation. In this Perspective, we first present an overview of the application of quantum-chemical techniques to study the intrinsic material properties and molecular- and nano-scale processes involved in device operation. In the second part, these quantum-chemical tools are applied to an oligomer-based study on a collection of donor-acceptor copolymers that have been used in the highest-efficiency solar cell devices reported to date. The quantum-chemical results are found to be in good agreement with the empirical data related to the electronic and optical properties. In particular, they provide insight into the natures of the electronic excitations responsible for the near-infrared/visible absorption profiles, as well as into the energetics of the low-lying singlet and triplet states. These results lead to a better understanding of the inherent differences among the materials, and highlight the usefulness of quantum chemistry as an instrument for material design. Importantly, the results also point to the need to continue the development of integrated, multi scale modeling approaches to provide a thorough understanding of the materials properties. © The Royal Society of Chemistry 2011.

  8. Annealing-free P3HT:PCBM-based organic solar cells via two halohydrocarbons additives with similar boiling points

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Xichang; Wang, Ting [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Yang, Ailing [Department of Physics, Ocean University of China, Qingdao 266100 (China); Yang, Chunpeng; Dou, Xiaowei; Chen, Weichao; Wang, Ning [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Yang, Renqiang, E-mail: yangrq@qibebt.ac.cn [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)

    2014-02-15

    Highlights: • Two halohydrocarbons were selected as additives for polymer solar cells. • The additives can improve the photocurrent of photovoltaic devices. • Extensive characterization of the blends was done to explore the mechanism. -- Abstract: Efficient annealing-free inverted bulk heterojunction (BHJ) organic solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C{sub 61}-butyric acid methyl ester (PCBM) (1:1, w/w) have been obtained using two easily accessible halohydrocarbons (1,6-dibromohexane (DBH) and 1-bromodecane (BD)) with the same boiling points as solvent additives. The devices treated with 2.5 wt% additives removed the grain boundary of the large PCBM-rich phase, resulting in more-uniform film morphology on the nanoscale. The more-uniform film morphology greatly improved the short circuit current density of the devices. Finally, PCEs of the devices processed with DBH and BD reached 3.81% and 3.68%, respectively. Both additives with almost the same boiling points had a similar impact on device performance, despite of different chemical structures with different polarities and other physical properties.

  9. Improvement of power efficiency of polymer solar cell based on P3HT: PCBM blends

    Science.gov (United States)

    Li, Weimin; Guo, Jinchuan; Sun, Xiuquan; Zhou, Bin

    2008-03-01

    The effect of interlayer on the performance of a poly[2-methoxy-5-(3',7'-dimethylocty)-1,4-phenylenevinylene] (MDMO-PPV)/1-(3-methoxycarbony 1)-propy1-1 phney1-(6-6)C 61 (PCBM) composite solar cell device has been reported recently. Herein we report bulk heterojunction organic solar cell with efficiency enhanced by interlayer made from blend film of regioregular poly(3-hexylthiophene)(P3HT) and PCBM. The interlayer, poly(9,9-dioctylfluorene)-co-N-(1,4-butylphenyl)diphenylamine)(TFB), was inserted between the poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic acid)(PEDOT:PPS) and the active layer. With the interlayer, the efficiency was enhanced due to the increased short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) obtained from testing and calculation. According to the analysis, the interlayer TFB, acting as an effective exciton-blocking layer, prevented the severe quenching of radiative excitons between the interface of PEDOT:PSS. In the study, the interlayer increased Jsc from 0.891 mA/cm2 to 1.025 mA/cm -2, Voc from 0.478 V to 0.526 V, and FF from 0.327 to 0.416, under illumination by white light from a solar simulator with an incident intensity of 80mW/cm2; the power conversion efficiency of the device reached higher value 0.280% comparing with 0.174% with no interlayer.

  10. 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.

  11. Rectenna solar cells

    CERN Document Server

    Moddel, Garret

    2013-01-01

    Rectenna Solar Cells discusses antenna-coupled diode solar cells, an emerging technology that has the potential to provide ultra-high efficiency, low-cost solar energy conversion. This book will provide an overview of solar rectennas, and provide thorough descriptions of the two main components: the diode, and the optical antenna. The editors discuss the science, design, modeling, and manufacturing of the antennas coupled with the diodes. The book will provide concepts to understanding the challenges, fabrication technologies, and materials required to develop rectenna structures. Written by e

  12. Efficient Electron Collection in Hybrid Polymer Solar Cells: In-Situ-Generated ZnO/Poly(3-hexylthiophene) Scaffolded by a TiO2 Nanorod Array.

    Science.gov (United States)

    Liao, Wen-Pin; Wu, Jih-Jen

    2013-06-01

    A nanoarchitectural hybrid polymer solar cell, integrating the ordered and the bulk heterojunction hybrid polymer solar cells, is fabricated by infiltrating the diethylzinc/poly(3-hexylthiophene) (P3HT) solution into the interstices of the TiO2 nanorod (NR) array. An inorganic network composed of tiny ZnO nanocrystals is constructed in the in-situ-generated hybrid within the interstice of the single-crystalline TiO2 NRs. The TiO2 NR array, which possesses a longer electron lifetime and an appropriate electron-transport rate, serves not only as an electron transporter/collector extended from fluorine-doped tin oxide (FTO) electrode to sustain the efficient electron collection but also as a scaffold to hold the sufficient amount of ZnO/P3HT hybrid. The in-situ-generated ZnO/P3HT hybrid layer with superior charge separation efficiency can therefore be thickened in the presence of a TiO2 NR array for increasing the light-harvesting efficiency. A notable efficiency of 2.46% is therefore attained in the TiO2 NR-ZnO/P3HT hybrid solar cell. PMID:26283138

  13. Polymer Solar Cells with Efficiency >10% Enabled via a Facile Solution-Processed Al-Doped ZnO Electron Transporting Layer

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2015-04-22

    A facile and low-temperature (125 °C) solution-processed Al-doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates is described. The ammonia-treatment of the aqueous AZO nanoparticle solution produces compact, crystalline, and smooth thin films, which retain the aluminum doping, and eliminates/reduces the native defects by nitrogen incorporation, making them good electron transporters and energetically matched with the fullerene acceptor. It is demonstrated that highly efficient solar cells can be achieved without the need for additional surface chemical modifications of the buffer layer, which is a common requirement for many metal oxide buffer layers to yield efficient solar cells. Also highly efficient solar cells are achieved with thick AZO films (>50 nm), highlighting the suitability of this material for roll-to-roll coating. Preliminary results on the applicability of AZO as electron injection layer in F8BT-based polymer light emitting diode are also presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Colloidal gold nanoparticles. Synthesis, characterization and effect in polymer/fullerene solar cells; Kolloidale Goldnanopartikel. Synthese, Charakterisierung und Wirkung in Polymer/Fulleren-Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Topp, Katja

    2011-06-08

    It has been reported in the literature that the efficiency of polymer/fullerene solar cells has been improved by the incorporation of Au nanoparticles. The improvement was attributed to an enhanced electrical conductivity of the active layer and to an enhanced light absorption due to the plasmon resonance of the Au nanoparticles. In this work colloidal Au nanoparticles coated with different stabilizing ligands were synthesized and characterized. Then the impact of their incorporation into P3HT/PCBM solar cells was studied. On the one hand the Au nanoparticles were incorporated into the bulk heterojunction active layer, otherwise they were deposited as an interlayer in the device set-up. No improvement of the solar cell efficiency could be observed neither for the incorporation of Au nanoparticles with isolating ligand shell nor for those with direct contact to the photoactive molecules. The efficiency even dropped, the more the higher the concentration of the Au nanoparticles was. Possible reasons are pointed out on the basis of detailed photophysical and structural investigations.

  15. Nanostructured photovoltaic devices for next generation solar cell

    Science.gov (United States)

    Kim, Sung Jin

    2008-10-01

    dissociation and charge transport, novel NQDs with functionalized ligands were developed. This research included the development of an approach to produce predefined patterns of quantum dots and multipod nanocrystals. The technique used optical lithography for direct writing of device structures for optoelectronic and electronic devices as well as the ability to change the ligand properties by using heat treatment. CdSe, CdTe, and PbSe nanocrystals were all functionalized by the incorporation of the functional ligand t-butoxycarbonyl (t-BOC). The ability to modify ligands of spin-casted nanocrystal layers by heating enables the fabrication of multi-layered structures. Moreover, the direct photopatterning of nanocrystal device structures was facilitated by the incorporation of a photo acid generator with the t-BOC functionalized nanocrystals. Finally, three different approaches that were recently developed to use t-BOC protected NQDs for photovoltaic devices will be discussed. The three types of devices that were developed include: (1) a multi-layered NQD all inorganic heterojunction photovoltaic devices; (2) a Schottky junction solar cell using a metal electrode on a NQD thin film; and (3) a hybrid (NQD/Polymer) bulk heterojunction device. Detailed characterization of these devices demonstrated that the t-BOC protected NQDs can be used to boost device performance (as compared to devices made from NQD with other ligands). This result provides significant advantages for realizing complicated device structures in the future.

  16. Dithiapyrannylidenes as efficient hole collection interfacial layers in organic solar cells.

    Science.gov (United States)

    Berny, Stéphane; Tortech, Ludovic; Véber, Michelle; Fichou, Denis

    2010-11-01

    One inherent limitation to the efficiency of photovoltaic solar cells based on polymer/fullerene bulk heterojunctions (BHJs) is the accumulation of positive charges at the anodic interface. The unsymmetrical charge collection of holes and electrons dramatically decreases the short-circuit current. Interfacial layers (IFLs) such as poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) have no effect on the unbalanced electron/hole transport across the BHJ. We report here on the use of dithiapyrannylidenes (DITPY), a new class of planar quinoid compounds, as efficient hole-transporting/electron-blocking layers in organic solar cells based on poly(3-hexylthiophene)/[6,6]-phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) BHJs. Inserting a 15-nm-thick IFL of 4,4'-bis(diphenyl-2,6-thiapyrannylidene) (DITPY-Ph(4)) between the indium-tin oxide electrode and the P3HT:PCBM BHJ prevents detrimental space-charge effects and favors recombination-limited currents. Current-sensing atomic force microscopy reveals a drastic increase of the hole-carrying pathways in DITPY-Ph(4) compared to PEDOT:PSS. In ambient conditions, photovoltaic cells using DITPY-Ph(4) exhibit an 8% increase in the current density, although the conversion efficiency remains slightly lower compared to PEDOT:PSS-based devices. Finally, we present a detailed analysis of the photocurrent generation, showing that DITPY-Ph(4) IFLs induce a transition from unproductive space-charge-limited currents to recombination-limited currents. PMID:21028838

  17. 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).

  18. Quantum dot solar cells

    CERN Document Server

    Wu, Jiang

    2013-01-01

    The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou

  19. Solar cell radiation handbook

    Science.gov (United States)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  20. π-Conjugated Organometallic Isoindigo Oligomer and Polymer Chromophores: Singlet and Triplet Excited State Dynamics and Application in Polymer Solar Cells.

    Science.gov (United States)

    Goswami, Subhadip; Gish, Melissa K; Wang, Jiliang; Winkel, Russell W; Papanikolas, John M; Schanze, Kirk S

    2015-12-01

    An isoindigo based π-conjugated oligomer and polymer that contain cyclometalated platinum(II) "auxochrome" units were subjected to photophysical characterization, and application of the polymer in bulk heterojunction polymer solar cells with PCBM acceptor was examined. The objective of the study was to explore the effect of the heavy metal centers on the excited state properties, in particular, intersystem crossing to a triplet (exciton) state, and further how this would influence the performance of the organometallic polymer in solar cells. The materials were characterized by electrochemistry, ground state absorption, emission, and picosecond-nanosecond transient absorption spectroscopy. Electrochemical measurements indicate that the cyclometalated units have a significant impact on the HOMO energy level of the chromophores, but little effect on the LUMO, which is consistent with localization of the LUMO on the isoindigo acceptor unit. Picosecond-nanosecond transient absorption spectroscopy reveals a transient with ∼100 ns lifetime that is assigned to a triplet excited state that is produced by intersystem crossing from a singlet state on a time scale of ∼130 ps. This is the first time that a triplet state has been observed for isoindigo π-conjugated chromophores. The performance of the polymer in bulk heterojunction solar cells was explored with PC61BM as an acceptor. The performance of the cells was optimum at a relatively high PCBM loading (1:6, polymer:PCBM), but the overall efficiency was relatively low with power conversion efficiency (PCE) of 0.22%. Atomic force microscopy of blend films reveals that the length scale of the phase separation decreases with increasing PCBM content, suggesting a reason for the increase in PCE with acceptor loading. Energetic considerations show that the triplet state in the polymer is too low in energy to undergo charge separation with PCBM. Further, due to the relatively low LUMO energy of the polymer, charge transfer

  1. Optimizing the fabrication process and interplay of device components of polymer solar cells using a field-based multiscale solar-cell algorithm

    International Nuclear Information System (INIS)

    Both the device composition and fabrication process are well-known to crucially affect the power conversion efficiency of polymer solar cells. Major advances have recently been achieved through the development of novel device materials and inkjet printing technologies, which permit to improve their durability and performance considerably. In this work, we demonstrate the usefulness of a recently developed field-based multiscale solar-cell algorithm to investigate the influence of the material characteristics, like, e.g., electrode surfaces, polymer architectures, and impurities in the active layer, as well as post-production treatments, like, e.g., electric field alignment, on the photovoltaic performance of block-copolymer solar-cell devices. Our study reveals that a short exposition time of the polymer bulk heterojunction to the action of an external electric field can lead to a low photovoltaic performance due to an incomplete alignment process, leading to undulated or disrupted nanophases. With increasing exposition time, the nanophases align in direction to the electric field lines, resulting in an increase of the number of continuous percolation paths and, ultimately, in a reduction of the number of exciton and charge-carrier losses. Moreover, we conclude by modifying the interaction strengths between the electrode surfaces and active layer components that a too low or too high affinity of an electrode surface to one of the components can lead to defective contacts, causing a deterioration of the device performance. Finally, we infer from the study of block-copolymer nanoparticle systems that particle impurities can significantly affect the nanostructure of the polymer matrix and reduce the photovoltaic performance of the active layer. For a critical volume fraction and size of the nanoparticles, we observe a complete phase transformation of the polymer nanomorphology, leading to a drop of the internal quantum efficiency. For other particle-numbers and -sizes

  2. Photovoltaic solar cell

    Science.gov (United States)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2013-11-26

    A photovoltaic solar cell for generating electricity from sunlight is disclosed. The photovoltaic solar cell comprises a plurality of spaced-apart point contact junctions formed in a semiconductor body to receive the sunlight and generate the electicity therefrom, the plurality of spaced-apart point contact junctions having a first plurality of regions having a first doping type and a second plurality of regions having a second doping type. In addition, the photovoltaic solar cell comprises a first electrical contact electrically connected to each of the first plurality of regions and a second electrical contact electrically connected to each of the second plurality of regions, as well as a passivation layer covering major surfaces and sidewalls of the photovoltaic solar cell.

  3. Improving the long-term stability of PBDTTPD polymer solar cells through material purification aimed at removing organic impurities

    KAUST Repository

    Mateker, William R.

    2013-01-01

    While bulk heterojunction (BHJ) solar cells fabricated from high M n PBDTTPD achieve power conversion efficiencies (PCE) as high as 7.3%, the short-circuit current density (JSC) of these devices can drop by 20% after seven days of storage in the dark and under inert conditions. This degradation is characterized by the appearance of S-shape features in the reverse bias region of current-voltage (J-V) curves that increase in amplitude over time. Conversely, BHJ solar cells fabricated from low Mn PBDTTPD do not develop S-shaped J-V curves. However, S-shapes identical to those observed in high Mn PBDTTPD solar cells can be induced in low M n devices through intentional contamination with the TPD monomer. Furthermore, when high Mn PBDTTPD is purified via size exclusion chromatography (SEC) to reduce the content of low molecular weight species, the JSC of polymer devices is significantly more stable over time. After 111 days of storage in the dark under inert conditions, the J-V curves do not develop S-shapes and the JSC degrades by only 6%. The S-shape degradation feature, symptomatic of low device lifetimes, appears to be linked to the presence of low molecular weight contaminants, which may be trapped within samples of high Mn polymer that have not been purified by SEC. Although these impurities do not affect initial device PCE, they significantly reduce device lifetime, and solar cell stability is improved by increasing the purity of the polymer materials. © 2013 The Royal Society of Chemistry.

  4. Design of perylene diimides for organic solar cell: Effect of molecular steric hindrance and extended conjugation

    Energy Technology Data Exchange (ETDEWEB)

    Kozma, Erika, E-mail: erika.kozma@ismac.cnr.it [Istituto per lo Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, 20133 Milano (Italy); Kotowski, Dariusz; Catellani, Marinella; Luzzati, Silvia [Istituto per lo Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, 20133 Milano (Italy); Cavazzini, Marco; Bossi, Alberto; Orlandi, Simonetta [Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, 20133 Milano (Italy); Bertini, Fabio [Istituto per lo Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, 20133 Milano (Italy)

    2015-08-01

    Core-substituted perylene diimides (PDI) are promising candidates as n-type semiconductor materials for organic photovoltaics. The chemical functionalization of perylene diimides in the bay positions is a versatile tool to obtain a series of electron acceptor materials with tunable electron affinity. These materials usually feature a donor-acceptor D-A structure in which the electron withdrawing PDI core is covalently linked with different electron donating chemical groups. The structural and electronic properties of the substituents define and modulate the optical/electrical properties of the semiconductor and the performance as photovoltaic material. In this work we designed two PDI molecules with D-A-D structure using spirobifluorene group as substituent directly linked to the perylene core (PDI-SF) and with insertion of a bithiophene moiety (PDI-BSF). In both molecules we found a reduced tendency to form aggregates in the solid state thanks to the cross-shaped rigid structure and strong steric hindrance of the spirobifluorene group. Additionally, in the case of PDI-BSF the presence of the bithiophene linker contributes significantly to extend the conjugation, resulting in a panchromatic absorption in the whole visible to NIR region. We present the synthesis of these materials and their characterisation in terms of absorption spectroscopy, cyclic voltammetry and computational calculations. Finally we show preliminary results of their use as active components in P3HT/PDIs bulk heterojunction solar cells. - Highlights: • New D-A-D n-type materials have been synthesized. • PDI-SF and PDI-BSF were used as acceptors in organic solar cells. • Performances of 1.32% were achieved in blend with P3HT in a BHJ conventional architecture.

  5. Solution-Processed 8-Hydroquinolatolithium as Effective Cathode Interlayer for High-Performance Polymer Solar Cells.

    Science.gov (United States)

    Liu, Wenqing; Liang, Tao; Chen, Qi; Yu, Zhikai; Zhang, Yingying; Liu, Yujing; Fu, Weifei; Tang, Feng; Chen, Liwei; Chen, Hongzheng

    2016-04-13

    Solution-processed 8-hydroxyquinolinatolithium (s-Liq) was successfully applied as an efficient cathode interlayer in bulk heterojunction polymer solar cells (PSCs), giving rise to enhancement in device performance. The ultraviolet photoelectron spectra results revealed that the presence of s-Liq could lower work function of Al cathode, allowing for the ohmic contacts with the fullerene acceptor for better electron extraction and also a larger work function difference between the two electrodes, which leads to an increase in open-circuit voltage (Voc). Scanning Kelvin probe microscopy study on the surface potential of active layers suggested that an interfacial dipole was formed in the s-Liq interlayer between the active layer and the Al cathode, which enhanced the intrinsic built-in potential in the device for better charge transportation and extraction. Consequently, the Voc, fill factor, and current density of the device can be improved by the introduction of s-Liq interlayer, leading to a power conversion efficiency (PCE) improvement. With PTB7 (or PTB7-Th) as the donor and PC71BM as the acceptor, the s-Liq-based PSC devices exhibited a PCE of 8.37% (or 9.04%), much higher than those of devices with the evaporated Liq (7.62%) or commonly used PFN (8.14%) as the cathode interlayer. Moreover, the s-Liq-based devices showed good stability, maintaining 75% (in N2) and 45% (in air) of the initial PCE after 7 days, respectively. These results suggest the great potential of s-Liq as cathode interlayer material for high-performance solar cells application. PMID:27015527

  6. Design of perylene diimides for organic solar cell: Effect of molecular steric hindrance and extended conjugation

    International Nuclear Information System (INIS)

    Core-substituted perylene diimides (PDI) are promising candidates as n-type semiconductor materials for organic photovoltaics. The chemical functionalization of perylene diimides in the bay positions is a versatile tool to obtain a series of electron acceptor materials with tunable electron affinity. These materials usually feature a donor-acceptor D-A structure in which the electron withdrawing PDI core is covalently linked with different electron donating chemical groups. The structural and electronic properties of the substituents define and modulate the optical/electrical properties of the semiconductor and the performance as photovoltaic material. In this work we designed two PDI molecules with D-A-D structure using spirobifluorene group as substituent directly linked to the perylene core (PDI-SF) and with insertion of a bithiophene moiety (PDI-BSF). In both molecules we found a reduced tendency to form aggregates in the solid state thanks to the cross-shaped rigid structure and strong steric hindrance of the spirobifluorene group. Additionally, in the case of PDI-BSF the presence of the bithiophene linker contributes significantly to extend the conjugation, resulting in a panchromatic absorption in the whole visible to NIR region. We present the synthesis of these materials and their characterisation in terms of absorption spectroscopy, cyclic voltammetry and computational calculations. Finally we show preliminary results of their use as active components in P3HT/PDIs bulk heterojunction solar cells. - Highlights: • New D-A-D n-type materials have been synthesized. • PDI-SF and PDI-BSF were used as acceptors in organic solar cells. • Performances of 1.32% were achieved in blend with P3HT in a BHJ conventional architecture

  7. Performance enhancement in inverted solar cells by interfacial modification of ZnO nanoparticle buffer layer.

    Science.gov (United States)

    Ambade, Swapnil B; Ambade, Rohan B; Kim, Seojin; Park, Hanok; Yoo, Dong Jin; Leel, Soo-Hyoung

    2014-11-01

    Polymer solar cells (PSCs) have attracted increasing attention in recent years. The rapid progress and mounting interest suggest the feasibility of PSC commercialization. However, critical issues such as stability and the weak nature of their interfaces posses quite a challenge. In the context of improving stability, PSCs with inverted geometry consising of inorganic oxide layer acting as an n-buffer offer quite the panacea. Zinc oxide (ZnO) is one of the most preferred semiconducting wide band gap oxides as an efficient cathode layer that effectively extracts and transports photoelectrons from the acceptor to the conducting indium-doped tin oxide (ITO) due to its high conductivity and transparency. However, the existence of a back charge transfer from metal oxides to electron-donating conjugated polymer and poor contact with the bulk heterojunction (BHJ) active layer results in serious interfacial recombination and leads to relatively low photovoltaic performance. One approach to improving the performance and charge selectivity of these types of inverted devices consists of modifying the interface between the inorganic metal oxide (e.g., ZnO) and organic active layer using a sub-monolayer of interfacial materials (e.g., functional dyes). In this work, we demonstrate that the photovoltaic parameters of inverted solar cells comprising a thin overlayer of functional dyes over ZnO nanoparticle as an n-buffer layer are highly influenced by the anchoring groups they possess. While an inverted PSC containing an n-buffer of only ZnO exhibited an overall power conversion efficiency (PCE) of 2.87%, the devices with an interlayer of dyes containing functional cyano-carboxylic, cyano-cyano, and carboxylic groups exhibited PCE of 3.52%, 3.39%, and 3.21%, respectively, due to increased forward charge collection resulting from enhanced electronic coupling between the ZnO and BHJ active layers. PMID:25958563

  8. Phenyl vs Alkyl Polythiophene: A Solar Cell Comparison Using a Vinazene Derivative as Acceptor

    KAUST Repository

    Woo, Claire H.

    2010-03-09

    The solar cell performance of poly[3-(4-n-octyl)-phenylthiophene] (POPT) and poly(3hexylthiophene) (P3HT) are compared in devices using 4,7-bis(2-(l-(2-ethylhexyl)-4,5-dicyanoimidazol-2-yl)vinyi)benzo[c][l,2,5] -thiadiazole (EV-BT) as the electron acceptor. Despite their reduced light absorption, POPT:EV-BT devices generate higher photocurrents in both bilayer and bulk heterojunction (BHJ) architectures than analogous P3HT:EV-BT devices. Optimized POPT:EV-BT BHJ devices achieve 1.4% average efficiency, whereas the analogous P3HT devices only reach 1.1%. Morphology does not account for the large difference in performance as AFM studies of the active layer suggest, comparable levels of phase separation in the two systems. Reverse bias analysis demonstrates that P3HT devices have a higher maximum potential than POPT devices, but P3HT devices appear to be more severely limited by recombination losses under standard operating conditions. A possible explanation for the superior performance in POPT devices is that the pendant phenyl ring in POPT can twist out-of-plane and increase the separation distance with the acceptor molecule. A larger donor/acceptor separation distance can destabilize the geminate pair and lead to more efficient charge separation in POPT:EV-BT devices. Our results emphasize the importance of donor/acceptor pair interactions and its effect on charge separation, processes in polymer solar cells. © 2010 American Chemical Society.

  9. Nanocrystal Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gur, Ilan

    2006-12-15

    This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.

  10. Thin silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  11. Sliver solar cells

    Science.gov (United States)

    Franklin, Evan; Blakers, Andrew; Everett, Vernie; Weber, Klaus

    2007-12-01

    Sliver solar cells are thin, mono-crystalline silicon solar cells, fabricated using micro-machining techniques combined with standard solar cell fabrication technology. Sliver solar modules can be efficient, low cost, bifacial, transparent, flexible, shadow-tolerant, and lightweight. Sliver modules require only 5 to 10% of the pure silicon and less than 5% of the wafer starts per MW p of factory output when compared with conventional photovoltaic modules. At ANU, we have produced 20% efficient Sliver solar cells using a robust, optimised cell fabrication process described in this paper. We have devised a rapid, reliable and simple method for extracting Sliver cells from a Sliver wafer, and methods for assembling modularised Sliver cell sub-modules. The method for forming these Sliver sub-modules, along with a low-cost method for rapidly forming reliable electrical interconnections, are presented. Using the sub-module approach, we describe low-cost methods for assembling and encapsulating Sliver cells into a range of module designs.

  12. Unsubstituted Benzodithiophene-Based Conjugated Polymers for High-Performance Organic Field-Effect Transistors and Organic Solar Cells.

    Science.gov (United States)

    Chen, Weichao; Xiao, Manjun; Han, Liangliang; Zhang, Jidong; Jiang, Huanxiang; Gu, Chuantao; Shen, Wenfei; Yang, Renqiang

    2016-08-01

    Unsubstituted benzo[1,2-b:4,5-b']dithiophene (BDT) was used to construct a high-performance conjugated polymer with 5,6-difluoro-4,7-bis[4-(2-octyldodecyl)thiophene-2-yl]benzo[c][1,2,5] thiadiazole (DTFFBT), named PBDT-DTFFBT. The polymer shows the low-lying highest occupied molecular orbital (HOMO) energy level (-5.40 eV) and a broad absorption spectra with strong vibronic absorption peak. Pure polymer films exhibit good crystallinity and edge-on orientation, partially attributed to the BDT units without any side chains, and as a result, the corresponding thin-film transistor showed excellent hole mobility over 1 cm(2) V(-1) s(-1). Interestingly, a well-distributed nanofibrillar polymer aggregation with face-on orientation was obviously formed when blending with PC71BM, which was in favor of the charge transportation. Consequently, the bulk heterojunction polymer solar cells based on the blends showed high power conversion efficiency of 9.29% with large short-current density (14.56 mA cm(-2)) and high fill factor (0.751) without any process additives or thermal annealing. PMID:27403850

  13. Improved performance of polymer solar cells using PBDTT-F-TT:PC71BM blend film as active layer

    Science.gov (United States)

    Zang, Yue; Gao, Xiumin; Lu, Xinmiao; Xin, Qing; Lin, Jun; Zhao, Jufeng

    2016-07-01

    A detailed study of high-efficiency polymer solar cells (PSCs) based on a low bandgap polymer PBDTT-F-TT and PC71BM as the bulk heterojunction (BHJ) layer is carried out. By using 1,8-diiodooctane (DIO) as solvent additive to control the morphology of active layer and comparing different device architecture to optimize the optical field distribution, the power conversion efficiency (PCE) of the resulted devices can be reached as high as 9.34%. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of DIO and device geometry on photovoltaic performance. It was found that the addition of DIO can significantly improve the nanoscale morphology and increased electron mobility in the BHJ layer. The inverted device architecture was chosen because the results from optical modeling shows that it offers better optical field distribution and exciton generation profile. Based on these results, a low-temperature processed ZnO was finally introduced as an electron transport layer to facility the fabrication on flexible substrates and showed comparable performance with the device based on conventional ZnO interlayer prepared by sol-gel process.

  14. Roles of Energy/Charge Cascades and Intermixed Layers at Donor/Acceptor Interfaces in Organic Solar Cells

    Science.gov (United States)

    Nakano, Kyohei; Suzuki, Kaori; Chen, Yujiao; Tajima, Keisuke

    2016-01-01

    The secret to the success of mixed bulk heterojunctions (BHJs) in yielding highly efficient organic solar cells (OSCs) could reside in the molecular structures at their donor/acceptor (D/A) interfaces. In this study, we aimed to determine the effects of energy and charge cascade structures at the interfaces by using well-defined planar heterojunctions (PHJs) as a model system. The results showed that (1) the charge cascade structure enhanced VOC because it shuts down the recombination pathway through charge transfer (CT) state with a low energy, (2) the charge cascade layer having a wider energy gap than the bulk material decreased JSC because the diffusion of the excitons from the bulk to D/A interface was blocked; the energy of the cascade layers must be appropriately arranged for both the charges and the excitons, and (3) molecular intermixing in the cascade layer opened the recombination path through the low-energy CT state and decreased VOC. Based on these findings, we propose improved structures for D/A interfaces in BHJs. PMID:27404948

  15. Quantum dot solar cell

    International Nuclear Information System (INIS)

    Full text: The much awaited desire of replacing fossil fuel with photovoltaic will remain a fairy tale if the myriad of issues facing solar cell development are marginalized. Foremost in the list is the issue of cost. Silicon has reached a stage where its use on large scale can no longer be lavishly depended upon. The demand for high grade silicon from the microelectronics and solar industries has soared leading to scarcity. New approach has to be sought. Notable is the increased attention on thin films such as cadmium telluride, copper indium gallium diselenide, amorphous silicon, and the not so thin non-crystalline family of silicon. While efforts to address the issues of stability, toxicity and efficiency of these systems are ongoing, another novel approach is quietly making its appearance - quantum dots. Quantum dots seem to be promising candidates for solar cells because of the opportunity to manipulate their energy levels allowing absorption of a wider solar spectrum. Utilization of minute quantity of these nano structures is enough to bring the cost of solar cell down and to ascertain sustainable supply of useful material. The paper outlines the progress that has been made on quantum dot solar cells. (author)

  16. Parameterization of solar cells

    Science.gov (United States)

    Appelbaum, J.; Chait, A.; Thompson, D.

    1992-10-01

    The aggregation (sorting) of the individual solar cells into an array is commonly based on a single operating point on the current-voltage (I-V) characteristic curve. An alternative approach for cell performance prediction and cell screening is provided by modeling the cell using an equivalent electrical circuit, in which the parameters involved are related to the physical phenomena in the device. These analytical models may be represented by a double exponential I-V characteristic with seven parameters, by a double exponential model with five parameters, or by a single exponential equation with four or five parameters. In this article we address issues concerning methodologies for the determination of solar cell parameters based on measured data points of the I-V characteristic, and introduce a procedure for screening of solar cells for arrays. We show that common curve fitting techniques, e.g., least squares, may produce many combinations of parameter values while maintaining a good fit between the fitted and measured I-V characteristics of the cell. Therefore, techniques relying on curve fitting criteria alone cannot be directly used for cell parameterization. We propose a consistent procedure which takes into account the entire set of parameter values for a batch of cells. This procedure is based on a definition of a mean cell representing the batch, and takes into account the relative contribution of each parameter to the overall goodness of fit. The procedure is demonstrated on a batch of 50 silicon cells for Space Station Freedom.

  17. Relating Charge Transport, Contact Properties, and Recombination to Open-Circuit Voltage in Sandwich-Type Thin-Film Solar Cells

    Science.gov (United States)

    Sandberg, Oskar J.; Sundqvist, Anton; Nyman, Mathias; Österbacka, Ronald

    2016-04-01

    To avoid surface recombination at the contacts and ensure efficient charge collection and high open-circuit voltages (VOC) in organic bulk heterojunction and perovskite solar cells, selective contacts with optimized energy levels are needed. However, a detailed theoretical understanding of how the device performance is affected by surface recombination at the contacts is still lacking. In this work, the influence of surface recombination on the open-circuit voltage in sandwich-type solar cells, with optically thin active layers, is clarified using numerical simulations. Furthermore, analytical expressions are derived, directly relating VOC to relevant device parameters, such as surface recombination velocity (Sp), mobility, and active layer thickness. At large Sp, the surface recombination is determined by diffusion-limited transport in the bulk. By reducing Sp, thus increasing the charge selectivity of the electrode, the surface recombination is eventually reduced as the transport becomes limited by interface kinetics at the contact. Depending on the interplay between surface recombination and bulk recombination, and the properties of the contacts, different operating regimes are identified featuring different light ideality factors and thickness dependences.

  18. Polymer solar cells with efficiency >10% enabled via a facile solution-processed Al-doped ZnO electron transporting layer

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2015-10-05

    The present work details a facile and low-temperature (125C) solution-processed Al-doped ZnO (AZO) buffer layer functioning very effectively as electron accepting/hole blocking layer for a wide range of polymer:fullerene bulk heterojunction systems, and yielding power conversion efficiency in excess of 10% (8%) on glass (plastic) substrates. We show that ammonia addition to the aqueous AZO nanoparticle solution is a critically important step toward producing compact and smooth thin films which partially retain the aluminum doping and crystalline order of the starting AZO nanocrystals. The ammonia treatment appears to reduce the native defects via nitrogen incorporation, making the AZO film a very good electron transporter and energetically matched with the fullerene acceptor. Importantly, highly efficient solar cells are achieved without the need for additional surface chemical passivation or modification, which has become an increasingly common route to improving the performance of evaporated or solution-processed ZnO ETLs in solar cells.

  19. Chalcogenophene comonomer comparison in small band gap diketopyrrolopyrrole-based conjugated polymers for high-performing field-effect transistors and organic solar cells

    KAUST Repository

    Ashraf, Raja Shahid

    2015-01-28

    The design, synthesis, and characterization of a series of diketopyrrolopyrrole-based copolymers with different chalcogenophene comonomers (thiophene, selenophene, and tellurophene) for use in field-effect transistors and organic photovoltaic devices are reported. The effect of the heteroatom substitution on the optical, electrochemical, and photovoltaic properties and charge carrier mobilities of these polymers is discussed. The results indicate that by increasing the size of the chalcogen atom (S < Se < Te), polymer band gaps are narrowed mainly due to LUMO energy level stabilization. In addition, the larger heteroatomic size also increases intermolecular heteroatom-heteroatom interactions facilitating the formation of polymer aggregates leading to enhanced field-effect mobilities of 1.6 cm2/(V s). Bulk heterojunction solar cells based on the chalcogenophene polymer series blended with fullerene derivatives show good photovoltaic properties, with power conversion efficiencies ranging from 7.1-8.8%. A high photoresponse in the near-infrared (NIR) region with excellent photocurrents above 20 mA cm-2 was achieved for all polymers, making these highly efficient low band gap polymers promising candidates for use in tandem solar cells. (Graph Presented).

  20. Side Chain Engineering of Naphthalenediimide-Based N-type Polymer for High-Performance All-Polymer Solar Cell near 6% Efficiency

    Science.gov (United States)

    Lee, Changyeon; Kang, Hyunbum; Lee, Wonho; Kim, Taesu; Kim, Ki-Hyun; Woo, Han Young; Wang, Cheng; Kim, Bumjoon; Pusan National University (PNU) Collaboration; Lawrence Berkeley National Laboratory Collaboration

    2015-03-01

    Despite the attractive features of all-polymer solar cells (all-PSCs), i.e., enhanced absorption coefficients, the tunability of their energetic and chemical properties and their thermal and mechanical stabilities, they still face the great challenge of having significantly low power conversion efficiency (PCE) values of only 3-5%. The prominent origins of the poor efficiency of all-PSCs are the undesirable features of the bulk-heterojunction (BHJ) blend morphology including the phase-separated large-scale domain size, reduced ordering of the polymer chains. Tuning side alkyl chains of conjugated polymers is an effective route for manipulating the blend morphology in BHJ type solar cells. However, the role of side chains in all-PSCs is poorly understood. Herein, we report high-performing all-PSCs with 5.96% efficiency by developing a series of naphthalenediimide (NDI)-based polymer acceptors with different alkyl side chains. We demonstrated that the use of the PNDIT with hexyldecyl side chains produced highly-ordered polymer stackings with strong face-on geometry and at the same time, forming the optimal BHJ morphology with finely separated phase domains, all of which contributed together to induce well-balanced μe/ μh ratio and generate efficient all-PSCs with PCEs near 6%.

  1. Solar cell element

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Akihiko; Matsumoto, Hitoshi; Uda, Hiroshi; Komatsu, Yasumitsu; Ikegami, Kiyoharu.

    1989-05-18

    In the existing CdS/CdTe-based solar cell element, nothing is formed except the component effective for generating electromotive force and the components necessary for leading, collecting and extracting the generated electricity, hence even when the element shows deterioration of its performance during its usage, it has been difficult to analyze the above situation. In addition, it has also a defect that its characteristic such as the transfer efficiency in the neighborhood of its glass substrate in connection also with its manufacturing process. In order to solve the above problematical points, this invention proposes, with regard to a CdS-based solar cell element composed by forming a thin film on its substrate, to make a blank space on the above substrate and form thereon a thin film which composes the solar cell element concerned alone or in a piling up manner. 4 figs.

  2. Correlation between blend morphology and recombination dynamics in additive-added P3HT:PCBM solar cells.

    Science.gov (United States)

    Solanki, Ankur; Wu, Bo; Salim, Teddy; Lam, Yeng Ming; Sum, Tze Chien

    2015-10-21

    The addition of a small amount of high boiling point solvent in organic donor/acceptor blends to control their morphology is a viable approach to enhance the power conversion efficiency of bulk heterojunction (BHJ) organic solar cells. Herein, through transient absorption spectroscopy (TAS) correlated with physical characterizations and device studies, we investigate the effects of a family of thiol-based additives (i.e., 1,5-pentanedithiol (PDT), 1,6-hexanedithiol (HDT) and 1,8-octanedithiol (ODT)) in P3HT:PCBM blend films in a bid to establish a morphology-function-charge dynamics relationship with their photovoltaic performances. The performance of solar cell devices (ηHDT = 2.8%, ηODT = 2.8%, ηPDT = 1.7%) is related to the additive-induced phase separation and the degree of ordering of P3HT. TAS uncovers a more efficient initial exciton and polaron generation in the additive-treated blend samples compared to the non-additive treated control sample. HDT and ODT-added blends exhibit decay dynamics and performances similar to those of the thermally annealed samples. However, the PDT-added blend exhibits a strong trap-assisted recombination in the subsequent nanosecond-microsecond timescales. We attribute this to the loss of charge carriers in the larger isolated P3HT domains due to the lack of percolation paths to the electrode. Our findings illustrate that understanding the complex interplay of the crystalline order, intermixed phases and percolation pathways is key to optimizing the performance of thermal-annealing free, additive-treated organic solar cells. PMID:26377255

  3. Organometallic tris(8-hydroxyquinoline)aluminum complexes as buffer layers and dopants in inverted organic solar cells

    International Nuclear Information System (INIS)

    Tris(8-hydroxyquinoline)aluminum (Alq3) is a frequently used material for organic light emitting diodes. The electronic properties and solubility can be tuned by chemical tailoring of the quinoline part, which makes it an interesting candidate for organic solar cells. Steady-state absorption and fluorescence, as well as time-resolved fluorescence properties of the parent Alq3 and a series of complexes consisting of derivatives, such as 4-substituted pyrazol, methylpyrazol, arylvinyl, and pyridinoanthrene moieties, of the quinoline ligand, were studied in solutions and in thin films. Suitability of the complexes as anodic buffer layers or dopants in inverted organic solar cells based on the well known bulk heterojunction of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) was tested. The devices equipped with the derivatives showed higher power conversion efficiency (η) compared to the photocells containing the parent Alq3. Open circuit voltage (Voc) was increased when the derivatives were utilized as the anodic buffer layer. Doping of the P3HT:PCBM with a small amount of Alq3 or its derivative improved short circuit current density, Voc, fill factor, and η, while the series resistance decreased. In addition, the devices were stable in air over several weeks without encapsulation. Possible mechanisms leading to the improvements in the photovoltaic performance by using the parent Alq3 or its derivative as buffer layer or dopant are discussed. - Highlights: ► Tris(8-hydroxyquinoline)aluminum (Alq3) complexes in inverted organic solar cells. ► The Alq3 complexes were used as an anodic buffer layer and as a dopant. ► Efficiency increased and the derivatives revealed varying open circuit voltage. ► Photovoltaic performance was stable after storage in a dark ambient atmosphere.

  4. Organometallic tris(8-hydroxyquinoline)aluminum complexes as buffer layers and dopants in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tolkki, Antti, E-mail: antti.tolkki@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Kaunisto, Kimmo [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Heiskanen, Juha P. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Omar, Walaa A.E. [Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Chemistry Branch, Department of Science and Mathematics, Suez Canal University, Suez 43721 (Egypt); Huttunen, Kirsi; Lehtimaeki, Suvi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Hormi, Osmo E.O. [Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Lemmetyinen, Helge [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland)

    2012-04-30

    Tris(8-hydroxyquinoline)aluminum (Alq{sub 3}) is a frequently used material for organic light emitting diodes. The electronic properties and solubility can be tuned by chemical tailoring of the quinoline part, which makes it an interesting candidate for organic solar cells. Steady-state absorption and fluorescence, as well as time-resolved fluorescence properties of the parent Alq{sub 3} and a series of complexes consisting of derivatives, such as 4-substituted pyrazol, methylpyrazol, arylvinyl, and pyridinoanthrene moieties, of the quinoline ligand, were studied in solutions and in thin films. Suitability of the complexes as anodic buffer layers or dopants in inverted organic solar cells based on the well known bulk heterojunction of poly(3-hexylthiophene) (P3HT) and phenyl-C{sub 61}-butyric acid methyl ester (PCBM) was tested. The devices equipped with the derivatives showed higher power conversion efficiency ({eta}) compared to the photocells containing the parent Alq{sub 3}. Open circuit voltage (V{sub oc}) was increased when the derivatives were utilized as the anodic buffer layer. Doping of the P3HT:PCBM with a small amount of Alq{sub 3} or its derivative improved short circuit current density, V{sub oc}, fill factor, and {eta}, while the series resistance decreased. In addition, the devices were stable in air over several weeks without encapsulation. Possible mechanisms leading to the improvements in the photovoltaic performance by using the parent Alq{sub 3} or its derivative as buffer layer or dopant are discussed. - Highlights: Black-Right-Pointing-Pointer Tris(8-hydroxyquinoline)aluminum (Alq{sub 3}) complexes in inverted organic solar cells. Black-Right-Pointing-Pointer The Alq{sub 3} complexes were used as an anodic buffer layer and as a dopant. Black-Right-Pointing-Pointer Efficiency increased and the derivatives revealed varying open circuit voltage. Black-Right-Pointing-Pointer Photovoltaic performance was stable after storage in a dark ambient

  5. Controlling hierarchical structures in organic solar cell using π- π interactions and their analysis using SANS and PSoXS

    International Nuclear Information System (INIS)

    Controlling the morphology of bulk-heterojunction (BHJ) films in organic photovoltaics (OPVs) is critical in overcoming inherent drawbacks (short exciton diffusion length and low charge mobility) of organic materials and achieving optimal device efficiency. Taking into account the energy conversion process, it is important to understand the hierarchical structure in organic solar cells ranging from molecule-scale and domain-scale to device-scale structure to realize efficient charge separation, transfer, and extraction. However, most of research has so far focused on the domain-level structure such as crystallinity, domain size, and domain orientation because there lacks methods to control hierarchical structures and systematic studies on it. In the present study, we report a new approach to control hierarchical structures in organic solar cells, which was characterized by PSoXS and SANS and their relationship with device performance. We could induce highly anisotropic P3HT crystalline structures (P3HT nanowires), which were grown in a direction of pi-pi stack, facilitating charge transport, through adding poor solvents for P3HT. In addition, the anisotropy of P3HT nanowire was controlled by utilizing additives which have different affinity with PCBM. By employing controlled P3HT nanowires having different anisotropy and following thermal annealing process, we could control the molecular orientation of P3HT at PCBM interfaces (molecular-scale), domain sizes of P3HT and PCBM (domain-scale) and network structures (device-scale). Based on our new method, we could effectively control the hierarchical structures of organic solar cells with an overall view on the relationship between multiscale nanostructure and device performance.

  6. Optoelectronics of solar cells

    CERN Document Server

    Smestad, Greg P

    2002-01-01

    With concerns about worldwide environmental security, global warming, and climate change due to emissions of carbon dioxide from the burning of fossil fuels, it is desirable to have a wide range of energy technologies in a nation's portfolio. Photovoltaics, or solar cells, are a viable option as a nonpolluting renewable energy source. This text is designed to be an overview of photovoltaic solar cells for those in the fields of optics and optical engineering, as well as those who are interested in energy policy, economics, and the requirements for efficient photo-to-electric energy conversion.

  7. Characterization of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Haerkoenen, J.; Tuominen, E.; Nybergh, K.; Ezer, Y.; Yli-Koski, M.; Sinkkonen, J. [Helsinki Univ. of Technology, Otaniemi (Finland). Dept. of Electrical and Communications Engineering

    1998-10-01

    Photovoltaic research in the Electron Physics Laboratory started in 1993, when laboratory joined the national TEKES/NEMO 2 research program. Since the beginning of the project, characterization as well as experimentally orientated development of the fabrication process of the solar cells were carried out parallery. The process development research started by the initiatives of the Finnish industry. At the moment a large amount of the laboratory personnel works on solar cell research and the financing comes mainly from external projects. The funding for the research has come from TEKES, Ministry of Education, Finnish Academy, GETA graduate school, special equipment grants of the university, and from the laboratory

  8. Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

    KAUST Repository

    Rumer, Joseph W.

    2015-02-01

    A bis-azide-based small molecule crosslinker is synthesized and evaluated as both a stabilizing and efficiency-boosting additive in bulk heterojunction organic photovoltaic cells. Activated by a noninvasive and scalable solution processing technique, polymer:fullerene blends exhibit improved thermal stability with suppressed polymer skin formation at the cathode and frustrated fullerene aggregation on ageing, with initial efficiency increased from 6% to 7%. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Pad printing as a film forming technique for polymer solar cells

    DEFF Research Database (Denmark)

    Krebs, Frederik C

    2009-01-01

    cells prepared by pad printing are presented. Devices were prepared on indium tin oxide substrates but in principle the entire photovoltaic device comprising front and back electrodes, barrier layers and active layer could be printed with no need for vacuum steps. The device geometry comprises a spin...... coated transparent zinc oxide front electrode, a pad printed active layer based on a bulk heterojunction of the thermocleavable polymer poly(3-(2-methylhexyloxycarbonyl)thiophene-co-thiopene) (P3MHOCT) and zinc oxide nanoparticles, spin coated PEDOT:PSS and finally a manually cast thermally cured silver...

  10. Electron-deficient N-alkyloyl derivatives of thieno[3,4-c]pyrrole-4,6-dione yield efficient polymer solar cells with open-circuit voltages > 1 v

    KAUST Repository

    Warnan, Julien

    2014-05-13

    Poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymer donors yield some of the highest open-circuit voltages (V OC, ca. 0.9 V) and fill factors (FF, ca. 70%) in conventional bulk-heterojunction (BHJ) solar cells with PCBM acceptors. Recent work has shown that the incorporation of ring substituents into the side chains of the BDT motifs in PBDTTPD can induce subtle variations in material properties, resulting in an increase of the BHJ device VOC to ∼1 V. In this contribution, we report on the synthesis of N-alkyloyl-substituted TPD motifs (TPD(CO)) and show that the electron-deficient motifs can further lower both the polymer LUMO and HOMO levels, yielding device VOC > 1 V (up to ca. 1.1 V) in BHJ solar cells with PCBM. Despite the high VOC achieved (i.e., low polymer HOMO), BHJ devices cast from TPD(CO)-based polymer donors can reach power conversion efficiencies (PCEs) of up to 6.7%, making these promising systems for use in the high-band-gap cell of tandem solar cells. © 2014 American Chemical Society.

  11. Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c] pyrrole-4,6-dione polymers direct self-assembly and solar cell performance

    KAUST Repository

    Cabanetos, Clement

    2013-03-27

    While varying the size and branching of solubilizing side chains in π-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages of 0.97 V in BHJ devices with PC71BM, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells. © 2013 American Chemical Society.

  12. A nanoscale study of charge extraction in organic solar cells: the impact of interfacial molecular configurations

    Science.gov (United States)

    Tang, Fu-Ching; Wu, Fu-Chiao; Yen, Chia-Te; Chang, Jay; Chou, Wei-Yang; Gilbert Chang, Shih-Hui; Cheng, Horng-Long

    2014-11-01

    In the optimization of organic solar cells (OSCs), a key problem lies in the maximization of charge carriers from the active layer to the electrodes. Hence, this study focused on the interfacial molecular configurations in efficient OSC charge extraction by theoretical investigations and experiments, including small molecule-based bilayer-heterojunction (sm-BLHJ) and polymer-based bulk-heterojunction (p-BHJ) OSCs. We first examined a well-defined sm-BLHJ model system of OSC composed of p-type pentacene, an n-type perylene derivative, and a nanogroove-structured poly(3,4-ethylenedioxythiophene) (NS-PEDOT) hole extraction layer. The OSC with NS-PEDOT shows a 230% increment in the short circuit current density compared with that of the conventional planar PEDOT layer. Our theoretical calculations indicated that small variations in the microscopic intermolecular interaction among these interfacial configurations could induce significant differences in charge extraction efficiency. Experimentally, different interfacial configurations were generated between the photo-active layer and the nanostructured charge extraction layer with periodic nanogroove structures. In addition to pentacene, poly(3-hexylthiophene), the most commonly used electron-donor material system in p-BHJ OSCs was also explored in terms of its possible use as a photo-active layer. Local conductive atomic force microscopy was used to measure the nanoscale charge extraction efficiency at different locations within the nanogroove, thus highlighting the importance of interfacial molecular configurations in efficient charge extraction. This study enriches understanding regarding the optimization of the photovoltaic properties of several types of OSCs by conducting appropriate interfacial engineering based on organic/polymer molecular orientations. The ultimate power conversion efficiency beyond at least 15% is highly expected when the best state-of-the-art p-BHJ OSCs are combined with present arguments

  13. NASA Facts, Solar Cells.

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    The design and function of solar cells as a source of electrical power for unmanned space vehicles is described in this pamphlet written for high school physical science students. The pamphlet is one of the NASA Facts Science Series (each of which consists of four pages) and is designed to fit in the standard size three-ring notebook. Review…

  14. MoO3–Au composite interfacial layer for high efficiency and air-stable organic solar cells

    DEFF Research Database (Denmark)

    Pan, Hongbin; Zuo, Lijian; Fu, Weifei;

    2013-01-01

    investigated by atomic force microscopy (AFM) and showed that the originally rough ITO substrate became smooth after depositing the composite film, with the root mean square roughness (RMS) decreased from 4.08nm to 1.81nm. The smooth surface reduced the bias-dependent carrier recombination, resulting in a......Efficient and stable polymer bulk-heterojunction solar cells based on regioregular poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) blend active layer have been fabricated with a MoO3–Au co-evaporation composite film as the anode interfacial layer (AIL). The optical...... large shunt resistance and thus improving the fill factor and efficiency of the devices. Additionally, the air stability of devices with different AILs (MoO3–Au composite, MoO3 and PEDOT:PSS) were studied and it was found that the MoO3–Au composite layer remarkably improved the stability of the solar...

  15. Degradation of CIGS solar cells

    NARCIS (Netherlands)

    Theelen, M.J.

    2015-01-01

    Thin film CIGS solar cells and individual layers within these solar cells have been tested in order to assess their long term stability. Alongside with the execution of standard tests, in which elevated temperatures and humidity levels are used, the solar cells have also been exposed to a combinatio

  16. Influence of the polymer matrix on the efficiency of hybrid solar cells based on silicon nanowires

    International Nuclear Information System (INIS)

    Highlights: ► Hybrid solar cells based on silicon nanowires have been fabricated. ► The relation between the morphology of the composite thin films and the charge transfer between the polymer matrices and SiNWs has been examined. ► We have investigated the effect of the polymer matrix on the photovoltaic characteristics. - Abstract: Poly (N-vinylcarbazole) (PVK):SiNWs and poly (2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenyl vinylene) (MEH-PPV):SiNWs bulk-heterojunctions (BHJ) have been elaborated from blends of SiNWs and the polymer in solution from a common solvent. Optical properties of these nanocomposites have been investigated by UV–vis absorption and photoluminescence (PL) spectral measurements. We have studied the charge transfer between SiNWs and the two polymers using the photoluminescence quenching of PVK and MEH-PPV which is a convenient signature of the reduced radiative recombination of the generated charge pairs upon exciton dissociation. We found that PVK and SiNWs constitutes the better donor–acceptor system. In order to understand the difference between PVK:SiNWs or MEH-PPV:SiNWs behaviours, photoluminescence responses were correlated with the topography (SEM) of the thin films. The photovoltaic effect of ITO/PEDOT:PSS/SiNWs:PVK/Al and ITO/PEDOT:PSS/SiNWs:MEH-PPV/Al structures was studied by current–voltage (I–V) measurements in dark and under illumination and interpreted on the basis of the charge transfer differences resulting from the morphologies.

  17. Characterization of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Haerkoenen, J.; Tuominen, E.; Nybergh, K.; Ezer, Y.; Yli-Koski, M.; Sinkkonen, J. [Helsinki Univ. of Technology (Finland). Dept. of Electrical and Communications Engineering

    1998-12-31

    Photovoltaic research began at the Electron Physics Laboratory of the Helsinki University of Tehnology in 1993, when the laboratory joined the national NEMO 2 research program. During the early stages of the photovoltaic research the main objective was to establish necessary measurement and characterisation routines, as well as to develop the fabrication process. The fabrication process development work has been supported by characterisation and theoretical modelling of the solar cells. Theoretical investigations have been concerned with systematic studies of solar cell parameters, such as diffusion lengths, surface recombination velocities and junction depths. The main result of the modelling and characterisation work is a method which is based on a Laplace transform of the so-called spatial collection efficiency function of the cell. The basic objective of the research has been to develop a fabrication process cheap enough to be suitable for commercial production

  18. Solar cell efficiency measurements

    International Nuclear Information System (INIS)

    Solar cells (and solar modules) have to be tested for their performance by means of sound reliable measurement procedures. The need for such measurements arises at various stages of research, of production, and of photovoltaic systems sizing and dimensioning. In fact, accurate measurements are necessary to the researcher, who studies new materials and new processes, to the manufacturer, who has to control his product and, finally, to the user, who needs sound measurements, in order to be in a position to make effective decisions about what kink of product will be needed and with what critical characteristics. In short, standard measurements that allow cells and modules to be characterized serve as a common language, allowing effective communication about products and requirements. 3 refs

  19. Organic Solar Cells with Boron- or Nitrogen-Doped Carbon Nanotubes in the P3HT : PCBM Photoactive Layer

    Directory of Open Access Journals (Sweden)

    Godfrey Keru

    2016-01-01

    Full Text Available Either boron- or nitrogen-doped carbon nanotubes (B- or N-CNTs were incorporated in bulk heterojunction organic solar cells photoactive layer composed of poly(3-hexylthiophene (P3HT : (6,6-phenyl-C61-butyric acid methyl ester (PCBM. The physical and chemical properties were investigated using different spectroscopic techniques. The cell performance was followed from their current-voltage (J-V characteristics. Recombination dynamics of the photo-generated free charge carriers were investigated using micro- to milliseconds transient absorption spectroscopy (TAS. Transmission electron microscopy (TEM images revealed the presence of cone structures and bamboo compartments in B-CNTs and N-CNTs, respectively. X-ray photoelectron spectroscopy (XPS revealed very little boron was substituted in the carbon network and presence of pyrrolic, pyridinic, and quaternary species of nitrogen in N-CNTs. J-V characteristics were found to be similar for the devices with B- and N-CNTs even though boron- and nitrogen-doped CNTs are known to have different properties, that is, p-type and n-type, respectively. TAS results showed that all devices had long lived free charge carriers but the devices with B- or N-CNTs had low power conservation efficiency and voltage.

  20. Formation of vertical concentration gradients in poly(3-hexylthiophene-2,5-diyl): Phenyl-C61-butyric acid methyl ester-graded bilayer solar cells

    International Nuclear Information System (INIS)

    In the present work, we demonstrate that graded bilayer solar cells provide a very interesting alternative to the bulk heterojunction active layers commonly used in organic photovoltaic cells. One of the main advantages of this type of active layers is the possibility to optimize independently both donor and acceptor layers. Using various process methods, we obtain active layers that demonstrate a donor–acceptor vertical concentration gradient. These devices exhibit not only a high fill factor but also a remarkable increase in open-circuit voltage (Voc). In order to understand the influence of the film morphology over the device parameters, we provide a complete study using energy-dispersive x-ray spectroscopy elemental mapping of the device cross sections, showing evidence that ideal donor–acceptor concentration gradient are required to obtain high fill factors. Furthermore, we use a simple equivalent electrical model to extrapolate device parameters such as reverse saturation current for a clearer understanding of the origin of the Voc increase. - Highlights: • Various donor–acceptor concentration-graded devices were fabricated. • Improved donor–acceptor concentration gradient enhances the photovoltaic properties. • The increased open-circuit voltage results from lower reverse saturation currents. • Adjusting the dimensions of buffer and intermixed layers enhances fill factor. • Ideal active layer morphologies lead to an increase of 30% of the efficiency

  1. Nanostructures for Organic Solar Cells

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jarosław

    2016-01-01

    The experimental work in this thesis is focused on the fabrication of nanostructures that can be implemented in organic solar cell (OSC) architecture for enhancement of the device performance. Solar devices made from organic material are gaining increased attention, compared to their inorganic...... for organic solar cell applications, opening new patterning possibilities....

  2. Morphologic improvement of the PBDTTT-C and PC71BM blend film with mixed solvent for high-performance inverted polymer solar cells

    International Nuclear Information System (INIS)

    Tracing the evolution of the bulk heterojunction structure, a dramatic promotion in the efficiency of polymer solar cells has been obtained in recent years. The active layer morphology of low-bandgap polymer solar cells is one of the critical factors for high-efficiency performance. In the past, the relationship between morphology improvement and the device’s characteristics (such as efficiency, fill factor and short-circuit current) in low-bandgap polymer solar cells has been studied intensively with regards to the conventional structure. Here we demonstrate the morphologic improvement of the poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b;4,5-b′]dithiophene) -2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiopene)-2,6-diyl]/[6,6] -phenyl C71 butyric acid methyl ester (PBDTTT-C/PC71BM) blend film for inverted solar cells. By utilizing a mixed solvent of dichlorobenzene/chlorobenzene with (1,8-diiodooctane) additives, the device efficiency can be significantly enhanced, from 0.92% to 4.43%. This enhancement is attributed to active layer morphologic improvement promoting carrier transport. Furthermore, the thickness optimization of the active layer and the electron blocking layer MoO3 further contributes to efficiency. The device performance could be achieved with an efficiency as high as 5.35%, an open-circuit voltage of 0.70 V, a short-circuit current density of 13.5 mA cm−2, and a fill factor of 57%. (paper)

  3. Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

    KAUST Repository

    Lee, Cheng-Kuang

    2014-12-10

    © 2014 American Chemical Society. The nanomorphologies of the bulk heterojunction (BHJ) layer of polymer solar cells are extremely sensitive to the electrode materials and thermal annealing conditions. In this work, the correlations of electrode materials, thermal annealing sequences, and resultant BHJ nanomorphological details of P3HT:PCBM BHJ polymer solar cell are studied by a series of large-scale, coarse-grained (CG) molecular simulations of system comprised of PEDOT:PSS/P3HT:PCBM/Al layers. Simulations are performed for various configurations of electrode materials as well as processing temperature. The complex CG molecular data are characterized using a novel extension of our graph-based framework to quantify morphology and establish a link between morphology and processing conditions. Our analysis indicates that vertical phase segregation of P3HT:PCBM blend strongly depends on the electrode material and thermal annealing schedule. A thin P3HT-rich film is formed on the top, regardless of bottom electrode material, when the BHJ layer is exposed to the free surface during thermal annealing. In addition, preferential segregation of P3HT chains and PCBM molecules toward PEDOT:PSS and Al electrodes, respectively, is observed. Detailed morphology analysis indicated that, surprisingly, vertical phase segregation does not affect the connectivity of donor/acceptor domains with respective electrodes. However, the formation of P3HT/PCBM depletion zones next to the P3HT/PCBM-rich zones can be a potential bottleneck for electron/hole transport due to increase in transport pathway length. Analysis in terms of fraction of intra- and interchain charge transports revealed that processing schedule affects the average vertical orientation of polymer chains, which may be crucial for enhanced charge transport, nongeminate recombination, and charge collection. The present study establishes a more detailed link between processing and morphology by combining multiscale molecular

  4. Transparent solar cell window module

    Energy Technology Data Exchange (ETDEWEB)

    Chau, Joseph Lik Hang; Chen, Ruei-Tang; Hwang, Gan-Lin; Tsai, Ping-Yuan [Nanopowder and Thin Film Technology Center, ITRI South, Industrial Technology Research Institute, Tainan County 709 (China); Lin, Chien-Chu [I-Lai Acrylic Corporation, Tainan City (China)

    2010-03-15

    A transparent solar cell window module based on the integration of traditional silicon solar cells and organic-inorganic nanocomposite material was designed and fabricated. The transparent solar cell window module was composed of a nanocomposite light-guide plate and traditional silicon solar cells. The preparation of the nanocomposite light-guide plate is easy without modification of the traditional casting process, the nanoparticles sol can be added directly to the polymethyl methacrylate (PMMA) monomer syrup during the process. The solar energy collected by this window can be used to power up small household electrical appliances. (author)

  5. Single Molecule Spectroelectrochemistry of Interfacial Charge Transfer Dynamics In Hybrid Organic Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Shanlin [Univ. of Alabama, Tuscaloosa, AL (United States)

    2014-11-16

    Our research under support of this DOE grant is focused on applied and fundamental aspects of model organic solar cell systems. Major accomplishments are: 1) we developed a spectroelectorchemistry technique of single molecule single nanoparticle method to study charge transfer between conjugated polymers and semiconductor at the single molecule level. The fluorescence of individual fluorescent polymers at semiconductor surfaces was shown to exhibit blinking behavior compared to molecules on glass substrates. Single molecule fluorescence excitation anisotropy measurements showed the conformation of the polymer molecules did not differ appreciably between glass and semiconductor substrates. The similarities in molecular conformation suggest that the observed differences in blinking activity are due to charge transfer between fluorescent polymer and semiconductor, which provides additional pathways between states of high and low fluorescence quantum efficiency. Similar spectroelectrochemistry work has been done for small organic dyes for understand their charge transfer dynamics on various substrates and electrochemical environments; 2) We developed a method of transferring semiconductor nanoparticles (NPs) and graphene oxide (GO) nanosheets into organic solvent for a potential electron acceptor in bulk heterojunction organic solar cells which employed polymer semiconductor as the electron donor. Electron transfer from the polymer semiconductor to semiconductor and GO in solutions and thin films was established through fluorescence spectroscopy and electroluminescence measurements. Solar cells containing these materials were constructed and evaluated using transient absorption spectroscopy and dynamic fluorescence techniques to understand the charge carrier generation and recombination events; 3) We invented a spectroelectorchemistry technique using light scattering and electroluminescence for rapid size determination and studying electrochemistry of single NPs in an

  6. Carbon Nanotube Solar Cells

    OpenAIRE

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabr...

  7. 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

  8. Side-chain tunability of furan-containing low-band-gap polymers provides control of structural order in efficient solar cells

    KAUST Repository

    Yiu, Alan T.

    2012-02-01

    The solution-processability of conjugated polymers in organic solvents has classically been achieved by modulating the size and branching of alkyl substituents appended to the backbone. However, these substituents impact structural order and charge transport properties in thin-film devices. As a result, a trade-off must be found between material solubility and insulating alkyl content. It was recently shown that the substitution of furan for thiophene in the backbone of the polymer PDPP2FT significantly improves polymer solubility, allowing for the use of shorter branched side chains while maintaining high device efficiency. In this report, we use PDPP2FT to demonstrate that linear alkyl side chains can be used to promote thin-film nanostructural order. In particular, linear side chains are shown to shorten π-π stacking distances between backbones and increase the correlation lengths of both π-π stacking and lamellar spacing, leading to a substantial increase in the efficiency of bulk heterojunction solar cells. © 2011 American Chemical Society.

  9. A spiro-bifluorene based 3D electron acceptor with dicyanovinylene substitution for solution-processed non-fullerene organic solar cells

    KAUST Repository

    Xia, Debin

    2015-04-20

    A novel electron acceptor, namely 2,2′-(12H,12′H-10,10′-spirobi[indeno[2,1-b]fluorene]-12,12′-diylidene)dimalononitrile (4CN-spiro), exhibiting a three-dimensional molecular structure was synthesized and its thermal, photophysical, electrochemical, crystal, and photovoltaic properties were investigated. The novel acceptor exhibits excellent thermal stability with a decomposition temperature of 460 °C, an absorption extending to 600 nm, and a LUMO level of −3.63 eV. Solution processed bulk-heterojunction (BHJ) organic solar cells were fabricated using 4CN-spiro as an acceptor and polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) as a donor polymer. The effect of the donor-to-acceptor ratio and processing conditions on the device performance was investigated. A device processed from tetrachloroethane with a donor to acceptor weight ratio of 1 : 1 yielded a power conversion efficiency (PCE) of 0.80%.

  10. Improved photovoltaic performance of inverted polymer solar cells through a sol-gel processed Al-doped ZnO electron extraction layer.

    Science.gov (United States)

    Kim, Jun Young; Cho, Eunae; Kim, Jaehoon; Shin, Hyeonwoo; Roh, Jeongkyun; Thambidurai, Mariyappan; Kang, Chan-mo; Song, Hyung-Jun; Kim, SeongMin; Kim, Hyeok; Lee, Changhee

    2015-09-21

    We demonstrate that nanocrystalline Al-doped zinc oxide (n-AZO) thin film used as an electron-extraction layer can significantly enhance the performance of inverted polymer solar cells based on the bulk heterojunction of poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and [6,6]-phenyl C(71)-butyric acid methyl ester (PC(70)BM). A synergistic study with both simulation and experiment on n-AZO was carried out to offer a rational guidance for the efficiency improvement. As a result, An n-AZO film with an average grain size of 13 to 22 nm was prepared by a sol-gel spin-coating method, and a minimum resistivity of 2.1 × 10(-3) Ω·cm was obtained for an Al-doping concentration of 5.83 at.%. When an n-AZO film with a 5.83 at.% Al concentration was inserted between the ITO electrode and the active layer (PCDTBT:PC(70)BM), the power conversion efficiency increased from 3.7 to 5.6%. PMID:26406762

  11. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  12. Diffused quantum well solar cell

    OpenAIRE

    Lee, ASW; Li, EH; Cheng, Y

    1995-01-01

    An alternative multi-bandgap solar cell made of diffused quantum well (DFQW) as the absorber is proposed here. The modeling of the spectral response and energy conversion efficiency of the solar cell will be shown. Significant enhancement in energy conversion efficiency is demonstrated when compared to that of the single bandgap cells.

  13. Solar cell materials developing technologies

    CERN Document Server

    Conibeer, Gavin J

    2014-01-01

    This book presents a comparison of solar cell materials, including both new materials based on organics, nanostructures and novel inorganics and developments in more traditional photovoltaic materials. It surveys the materials and materials trends in the field including third generation solar cells (multiple energy level cells, thermal approaches and the modification of the solar spectrum) with an eye firmly on low costs, energy efficiency and the use of abundant non-toxic materials.

  14. Thermal Management of Solar Cells

    OpenAIRE

    Saadah, Mohammed Ahmed

    2013-01-01

    The focus on solar cells as a source of photovoltaic energy is rapidly increasing nowadays. The amount of sun's energy entering earth surface in one hour is more than the world consume in one year. The photovoltaic market has been increasing by more than 20% annually since 2002. Improving solar cells aims at increasing the power conversion efficiency and reducing manufacturing costs. Crystalline silicon is the most commonly used material in making solar cells with more than 90% market use. So...

  15. Bifacial tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wojtczuk, Steven J.; Chiu, Philip T.; Zhang, Xuebing; Gagnon, Edward; Timmons, Michael

    2016-06-14

    A method of fabricating on a semiconductor substrate bifacial tandem solar cells with semiconductor subcells having a lower bandgap than the substrate bandgap on one side of the substrate and with subcells having a higher bandgap than the substrate on the other including, first, growing a lower bandgap subcell on one substrate side that uses only the same periodic table group V material in the dislocation-reducing grading layers and bottom subcells as is present in the substrate and after the initial growth is complete and then flipping the substrate and growing the higher bandgap subcells on the opposite substrate side which can be of different group V material.

  16. Dye Sensitized Solar Cell, DSSC

    OpenAIRE

    Pongsatorn Amornpitoksuk; Nareelak Leesakul

    2003-01-01

    A dye sensitized solar cell is a new type of solar cell. The operating system of this solar cell type is similar to plant’s photosynthesis process. The sensitizer is available for absorption light and transfer electrons to nanocrystalline metal oxide semiconductor. The ruthenium(II) complexes with polypyridyl ligands are usually used as the sensitizers in solar cell. At the present time, the complex of [Ru(2,2',2'’-(COOH)3- terpy)(NCS)3] is the most efficient sensitizer. The total photon to c...

  17. Space Solar Cell Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Measures, characterizes, and analyzes photovoltaic materials and devices. The primary focus is the measurement and characterization of solar cell response...

  18. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  19. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  20. 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

  1. An Introduction to Solar Cells

    Science.gov (United States)

    Feldman, Bernard J.

    2010-01-01

    Most likely, solar cells will play a significant role in this country's strategy to address the two interrelated issues of global warming and dependence on imported oil. The purpose of this paper is to present an explanation of how solar cells work at an introductory high school, college, or university physics course level. The treatment presented…

  2. Nanostructuring of Solar Cell Surfaces

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk

    Solar energy is by far the most abundant renewable energy source available, but the levelized cost of solar energy is still not competitive with that of fossil fuels. Therefore there is a need to improve the power conversion effciency of solar cells without adding to the production cost. The main...... objective of this PhD thesis is to develop nanostructured silicon (Si) solar cells with higher power conversion efficiency using only scalable and cost-efficient production methods. The nanostructures, known as 'black silicon', are fabricated by single-step, maskless reactive ion etching and used as front...... and characterized for comparison. Power conversion eciency of 16.5% was obtained for this batch of RIE-textured Si solar cells. The eciency of the KOH-textured reference cell was 17.8%. Quantum Efficiency measurements and carrier loss analysis show that the lower eciency of the RIE-textured cells is primarily due...

  3. Back wall solar cell

    Science.gov (United States)

    Brandhorst, H. W., Jr. (Inventor)

    1978-01-01

    A solar cell is disclosed which comprises a first semiconductor material of one conductivity type with one face having the same conductivity type but more heavily doped to form a field region arranged to receive the radiant energy to be converted to electrical energy, and a layer of a second semiconductor material, preferably highly doped, of opposite conductivity type on the first semiconductor material adjacent the first semiconductor material at an interface remote from the heavily doped field region. Instead of the opposite conductivity layer, a metallic Schottky diode layer may be used, in which case no additional back contact is needed. A contact such as a gridded contact, previous to the radiant energy may be applied to the heavily doped field region of the more heavily doped, same conductivity material for its contact.

  4. Mechanistic insights into UV-induced electron transfer from PCBM to titanium oxide in inverted-type organic thin film solar cells using AC impedance spectroscopy.

    Science.gov (United States)

    Kuwabara, Takayuki; Iwata, Chiaki; Yamaguchi, Takahiro; Takahashi, Kohshin

    2010-08-01

    An inverted organic bulk-heterojunction solar cell containing amorphous titanium oxide (TiOx) as an electron collection electrode with the structure ITO/TiO(x)/[6,6]-phenyl C(61) butyric acid methyl ester (PCBM): regioregular poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxylenethiophene):poly(4-styrene sulfonic acid)/Au (TiO(x) cell) was fabricated. Its complicated photovoltaic properties were investigated by photocurrent-voltage and alternating current impedance spectroscopy measurements. The TiO(x) cell required a significant amount of time (approximately 60 min) to reach its maximum power conversion efficiency (PCE) of 2.6%. To investigate the reason for this slow photoresponse, we investigated the influences of UV light and water molecules adsorbed on the TiO(x) layer. Surface treatment of the TiO(x) cell with water induced a rapid photoresponse and enhanced the performance, giving a PCE of 2.97%. However, the durability of the treated cell was considerably inferior that of the untreated cell because of UV-induced photodegradation. The cause of the rapid photoresponse of the treated cell was attributed to the formation of hydrogen bonds between adsorbed water molecules and carbonyl oxygen atoms in PCBM close to the TiO(x) surface. When the TiO(x) surface was positively charged by UV-induced holes, the carbonyl oxygen in PCBM close to the TiO(x) surface can quickly join to the TiO(x) surface, rapidly transporting photogenerated electrons from PCBM to TiO(x) in competition with the photocatalyzed degradation. The experimental results suggested that the slow photoresponse of the untreated TiO(x) cell was because the morphology of the photoactive organic layer changed gradually upon irradiation to improve the transport of photocarriers at the TiO(x)/PCBM:P3HT interface. PMID:20735096

  5. Comparing the Device Physics and Morphology of Polymer Solar Cells Employing Fullerenes and Non-Fullerene Acceptors

    KAUST Repository

    Bloking, Jason T.

    2014-04-23

    There is a need to find electron acceptors for organic photovoltaics that are not based on fullerene derivatives since fullerenes have a small band gap that limits the open-circuit voltage (VOC), do not absorb strongly and are expensive. Here, a phenylimide-based acceptor molecule, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (HPI-BT), that can be used to make solar cells with VOC values up to 1.11 V and power conversion efficiencies up to 3.7% with two thiophene polymers is demonstrated. An internal quantum efficiency of 56%, compared to 75-90% for polymer-fullerene devices, results from less efficient separation of geminate charge pairs. While favorable energetic offsets in the polymer-fullerene devices due to the formation of a disordered mixed phase are thought to improve charge separation, the low miscibility (<5 wt%) of HPI-BT in polymers is hypothesized to prevent the mixed phase and energetic offsets from forming, thus reducing the driving force for charges to separate into the pure donor and acceptor phases where they can be collected. A small molecule electron acceptor, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (HPI-BT), achieves efficiencies of 3.7% and open-circuit voltage values of 1.11 V in bulk heterojunction (BHJ) devices with polythiophene donor materials. The lower internal quantum efficiency (56%) in these non-fullerene acceptor devices is attributed to an absence of the favorable energetic offsets resulting from nanoscale mixing of donor and acceptor found in comparable fullerene-based devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Co-functionalized organic/inorganic hybrid ZnO nanorods as electron transporting layers for inverted organic solar cells.

    Science.gov (United States)

    Ambade, Swapnil B; Ambade, Rohan B; Eom, Seung Hun; Baek, Myung-Jin; Bagde, Sushil S; Mane, Rajaram S; Lee, Soo-Hyoung

    2016-03-01

    In an unprecedented attempt, we present an interesting approach of coupling solution processed ZnO planar nanorods (NRs) by an organic small molecule (SM) with a strong electron withdrawing cyano moiety and the carboxylic group as binding sites by a facile co-functionalization approach. Direct functionalization by SMs (SM-ZnO NRs) leads to higher aggregation owing to the weaker solubility of SMs in solutions of ZnO NRs dispersed in chlorobenzene (CB). A prior addition of organic 2-(2-methoxyethoxy)acetic acid (MEA) over ZnO NRs not only inhibits aggregation of SMs over ZnO NRs, but also provides enough sites for the SM to strongly couple with the ZnO NRs to yield transparent SM-MEA-ZnO NRs hybrids that exhibited excellent capability as electron transporting layers (ETLs) in inverted organic solar cells (iOSCs) of P3HT:PC60BM bulk-heterojunction (BHJ) photoactive layers. A strongly coupled SM-MEA-ZnO NR hybrid reduces the series resistance by enhancing the interfacial area and tunes the energy level alignment at the interface between the (indium-doped tin oxide, ITO) cathode and BHJ photoactive layers. A significant enhancement in power conversion efficiency (PCE) was achieved for iOSCs comprising ETLs of SM-MEA-ZnO NRs (3.64%) advancing from 0.9% for pristine ZnO NRs, while the iOSCs of aggregated SM-ZnO NRs ETL exhibited a much lower PCE of 2.6%, thus demonstrating the potential of the co-functionalization approach. The superiority of the co-functionalized SM-MEA-ZnO NRs ETL is also evident from the highest PCE of 7.38% obtained for the iOSCs comprising BHJ of PTB7-Th:PC60BM compared with extremely poor 0.05% for non-functionalized ZnO NRs. PMID:26864170

  7. Photon management in solar cells

    CERN Document Server

    Rau, Uwe; Gombert, Andreas

    2015-01-01

    Written by renowned experts in the field of photon management in solar cells, this one-stop reference gives an introduction to the physics of light management in solar cells, and discusses the different concepts and methods of applying photon management. The authors cover the physics, principles, concepts, technologies, and methods used, explaining how to increase the efficiency of solar cells by splitting or modifying the solar spectrum before they absorb the sunlight. In so doing, they present novel concepts and materials allowing for the cheaper, more flexible manufacture of solar cells and systems. For educational purposes, the authors have split the reasons for photon management into spatial and spectral light management. Bridging the gap between the photonics and the photovoltaics communities, this is an invaluable reference for materials scientists, physicists in industry, experimental physicists, lecturers in physics, Ph.D. students in physics and material sciences, engineers in power technology, appl...

  8. 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.

  9. Plastic solar cells : understanding the special additive

    OpenAIRE

    van Franeker, Jacobus J.; Janssen, René A.J.

    2015-01-01

    Solar cells use freely available sunlight to make electricity. At the present time, solar electricity does not come cheap, because solar panels are rather expensive. Now imagine that we could reduce costs by printing solar panels like we print newspapers! We can do just that with plastic solar cells. In this article, we explain the basic working principles of these novel plastic solar cells and then show how a stunning threefold increase in solar energy efficiency can be achieved by including...

  10. Fundamentals of thin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. [Univ. of California, Los Angeles, CA (United States)

    1995-08-01

    It is now widely recognized that thin solar cells can present certain advantages for performance and cost. This is particularly the case when light trapping in the semiconductor film is incorporated, as compensation for the diminished single path thickness of the solar cell. In a solar cell thinner than a minority carrier diffusion length, the current collection is of course very easy. More importantly the concentration of an equivalent number of carriers in a thinner volume results in a higher Free Energy, or open circuit voltage. This extra Free Energy may be regarded as due to the concentration factor, just as it would be for photons, electrons, or for any chemical species. The final advantage of a thin solar cell is in the diminished material usage, a factor of considerable importance when we consider the material cost of the high quality semiconductors which we hope to employ.

  11. Solvent Annealing Effects in Dithieno[3,2-b:2',3'-d]pyrrole–5,6-Difluorobenzo[c][1,2,5]thiadiazole Small Molecule Donors for BHJ Solar Cells

    KAUST Repository

    Wang, Kai

    2016-06-17

    Low-bandgap small molecule (SM) donors that can be solution-processed with fullerene acceptors (e.g. PC61/71BM) are proving particularly promising in bulk-heterojunction (BHJ) solar cells. Compared to their π-conjugated polymer counterparts, SM donors are well defined (monodispersed) and more synthetically modular –with relatively wide ranges of bandgaps achievable in stepwise couplings of various donor and acceptor motifs. However, the optimization of SM-fullerene morphologies and BHJ device efficiencies relies more specifically on the use of processing additives, post-processing thermal or solvent vapor annealing (SVA) approaches, and achieving adequate interpenetrating networks and structural order in BHJ thin films can be challenging. In this report, we examine the correlated effects of molecular structure and post-processing SVA on the BHJ solar cell performance of a set of π-extended SM donors composed of dithieno[3,2-b:2\\',3\\'-d]pyrrole (DTP) and 5,6-difluorobenzo[c][1,2,5]thiadiazole ([2F]BT) units. In these systems (SM1-3), the introduction of additional alkyl substituents and unsubstituted thiophene rings on the peripheral unit groups critically impacts the effects of SVA steps on BHJ solar cell efficiency. We show that the more π-extended and alkyl-substituted analogue SM3 stands out –with BHJ device efficiencies of ca. 6% obtained from SVA with CS2– while SVA-treated SM3-based active layers also show the most favorable ordering and carrier mobility patterns. However, unlike numbers of SM donors reported in recent years, DTP–[2F]BT SM analogues are in general not prone to dramatic performance variations in BHJ thin films cast with processing additives. Our results indicate that the role of SVA steps is not independent of the molecular structure of the SM donors used in the BHJ solar cells.

  12. Electronic structure, molecular orientation, charge transfer dynamics and solar cells performance in donor/acceptor copolymers and fullerene: Experimental and theoretical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Basabe, Y.; Borges, B. G. A. L.; Rocco, M. L. M., E-mail: lsroman@fisica.ufpr.br, E-mail: luiza@iq.ufrj.br [Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909 (Brazil); Marchiori, C. F. N.; Yamamoto, N. A. D.; Koehler, M.; Roman, L. S., E-mail: lsroman@fisica.ufpr.br, E-mail: luiza@iq.ufrj.br [Departament of Physics, Federal University of Paraná, Curitiba 81531-990 (Brazil); Macedo, A. G. [Departament of Physics, Technological Federal University of Paraná, Curitiba 80230-901 (Brazil)

    2014-04-07

    By combining experimental and theoretical approaches, the electronic structure, molecular orientation, charge transfer dynamics and solar cell performance in donor/acceptor copolymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PSiF-DBT) films and blended with 6,6.-phenyl-C 61-butyric acid methyl ester (PSiF-DBT:PCBM) were investigated. Good agreement between experimental and theoretical PSiF-DBT UV-Vis absorption spectrum is observed and the main molecular orbitals contributing to the spectrum were determined using DFT single point calculations. Non-coplanar configuration was determined by geometric optimization calculation in isolated PSiF-DBT pentamer and corroborated by angular variation of the sulphur 1s near-edge X-ray absorption fine structure (NEXAFS) spectra. Edge-on and plane-on molecular orientations were obtained for thiophene and benzothiadiazole units, respectively. A power conversion efficiency up to 1.58%, open circuit voltage of 0.51 V, short circuit current of 8.71 mA/cm{sup 2} and a fill factor of 35% was obtained using blended PSiF-DBT:PCBM as active layer in a bulk heterojunction solar cell. Ultrafast electron dynamics in the low-femtosecond regime was evaluated by resonant Auger spectroscopy using the core-hole clock methodology around sulphur 1s absorption edge. Electron delocalization times for PSiF-DBT and PSiF-DBT:PCBM polymeric films were derived for selected excitation energies corresponding to the main transitions in the sulphur 1s NEXAFS spectra. The mixture of PSiF-DBT with PCBM improves the charge transfer process involving the π* molecular orbital of the thiophene units.

  13. Electronic structure, molecular orientation, charge transfer dynamics and solar cells performance in donor/acceptor copolymers and fullerene: Experimental and theoretical approaches

    International Nuclear Information System (INIS)

    By combining experimental and theoretical approaches, the electronic structure, molecular orientation, charge transfer dynamics and solar cell performance in donor/acceptor copolymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PSiF-DBT) films and blended with 6,6.-phenyl-C 61-butyric acid methyl ester (PSiF-DBT:PCBM) were investigated. Good agreement between experimental and theoretical PSiF-DBT UV-Vis absorption spectrum is observed and the main molecular orbitals contributing to the spectrum were determined using DFT single point calculations. Non-coplanar configuration was determined by geometric optimization calculation in isolated PSiF-DBT pentamer and corroborated by angular variation of the sulphur 1s near-edge X-ray absorption fine structure (NEXAFS) spectra. Edge-on and plane-on molecular orientations were obtained for thiophene and benzothiadiazole units, respectively. A power conversion efficiency up to 1.58%, open circuit voltage of 0.51 V, short circuit current of 8.71 mA/cm2 and a fill factor of 35% was obtained using blended PSiF-DBT:PCBM as active layer in a bulk heterojunction solar cell. Ultrafast electron dynamics in the low-femtosecond regime was evaluated by resonant Auger spectroscopy using the core-hole clock methodology around sulphur 1s absorption edge. Electron delocalization times for PSiF-DBT and PSiF-DBT:PCBM polymeric films were derived for selected excitation energies corresponding to the main transitions in the sulphur 1s NEXAFS spectra. The mixture of PSiF-DBT with PCBM improves the charge transfer process involving the π* molecular orbital of the thiophene units

  14. Solar cell with back side contacts

    Science.gov (United States)

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  15. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  16. Biomimetic Dye Aggregate Solar Cells

    OpenAIRE

    Marek, Peter L.

    2012-01-01

    A biomimetic self-assembling dye, which forms aggregates that mimic the natural light-harvesting system of special photosynthetic active bacteria, has been investigated towards its applicability to solar cells. This fully synthetic dye, self-assembles to orderly structured nano- to micrometer sized rod-shaped aggregates, which might improve solar cells based on conventional organic dyes. In order to use the full potential of the dye aggregates, the self-assembly needed to be controlled and a ...

  17. Graphene Applications in Solar Cells

    Directory of Open Access Journals (Sweden)

    JIANG Li-Li, LU Xiong

    2012-11-01

    Full Text Available Graphene has attracted much attention in fields such as physics, chemistry, and materials science, because of its unique properties and potential applications. Interests in graphene applications in solar cells have been motivated to meet the demand of improving the photovoltaic performance. Graphene applications in solar cells, such as graphene based transparent conducting electrodes, photoanodes, and accepter materials, are reviewed systematically. The further prospects and improvement of graphene applications are also discussed.

  18. Plasma Etching Improves Solar Cells

    Science.gov (United States)

    Bunyan, S. M.

    1982-01-01

    Etching front surfaces of screen-printed silicon photovoltaic cells with sulfur hexafluoride plasma found to increase cell performance while maintaining integrity of screen-printed silver contacts. Replacement of evaporated-metal contacts with screen-printed metal contacts proposed as one way to reduce cost of solar cells for terrestrial applications.

  19. Industrial Silicon Wafer Solar Cells

    Directory of Open Access Journals (Sweden)

    Dirk-Holger Neuhaus

    2007-01-01

    Full Text Available In 2006, around 86% of all wafer-based silicon solar cells were produced using screen printing to form the silver front and aluminium rear contacts and chemical vapour deposition to grow silicon nitride as the antireflection coating onto the front surface. This paper reviews this dominant solar cell technology looking into state-of-the-art equipment and corresponding processes for each process step. The main efficiency losses of this type of solar cell are analyzed to demonstrate the future efficiency potential of this technology. In research and development, more various advanced solar cell concepts have demonstrated higher efficiencies. The question which arises is “why are new solar cell concepts not transferred into industrial production more frequently?”. We look into the requirements a new solar cell technology has to fulfill to have an advantage over the current approach. Finally, we give an overview of high-efficiency concepts which have already been transferred into industrial production.

  20. Efficient organic solar cells using copper(I) iodide (CuI) hole transport layers

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Ying [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Department of Physics and Centre for Plastic Electronics, Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Yaacobi-Gross, Nir; Perumal, Ajay K.; Faber, Hendrik A.; Bradley, Donal D. C.; Anthopoulos, Thomas D., E-mail: zhqhe@bjtu.edu.cn, E-mail: t.anthopoulos@imperial.ac.uk [Department of Physics and Centre for Plastic Electronics, Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Vourlias, George; Patsalas, Panos A. [Department of Physics, Laboratory of Applied Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); He, Zhiqun, E-mail: zhqhe@bjtu.edu.cn, E-mail: t.anthopoulos@imperial.ac.uk [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China)

    2015-06-15

    We report the fabrication of high power conversion efficiency (PCE) polymer/fullerene bulk heterojunction (BHJ) photovoltaic cells using solution-processed Copper (I) Iodide (CuI) as hole transport layer (HTL). Our devices exhibit a PCE value of ∼5.5% which is equivalent to that obtained for control devices based on the commonly used conductive polymer poly(3,4-ethylenedioxythiophene): polystyrenesulfonate as HTL. Inverted cells with PCE >3% were also demonstrated using solution-processed metal oxide electron transport layers, with a CuI HTL evaporated on top of the BHJ. The high optical transparency and suitable energetics of CuI make it attractive for application in a range of inexpensive large-area optoelectronic devices.

  1. Efficient organic solar cells using copper(I) iodide (CuI) hole transport layers

    International Nuclear Information System (INIS)

    We report the fabrication of high power conversion efficiency (PCE) polymer/fullerene bulk heterojunction (BHJ) photovoltaic cells using solution-processed Copper (I) Iodide (CuI) as hole transport layer (HTL). Our devices exhibit a PCE value of ∼5.5% which is equivalent to that obtained for control devices based on the commonly used conductive polymer poly(3,4-ethylenedioxythiophene): polystyrenesulfonate as HTL. Inverted cells with PCE >3% were also demonstrated using solution-processed metal oxide electron transport layers, with a CuI HTL evaporated on top of the BHJ. The high optical transparency and suitable energetics of CuI make it attractive for application in a range of inexpensive large-area optoelectronic devices

  2. Comparison of manufactured and modeled solar cell

    OpenAIRE

    Strachala, D.; Hylský, J.

    2015-01-01

    The aim of the work is to compare the model of monocrystalline silicon solar cell in PC1D with the real solar cell structure in terms of using a model in manufacture process. Real solar cell was firstly measured and analyzed to determine input parameters for a simulation and then realized in free available PC1D software. Degree of conformity of modeled and real solar cell was in the end established for basic prediction of solar cell parameters before manufacturing process.

  3. Improved hole mobility and suppressed trap density in polymer-polymer dual donor based highly efficient organic solar cells

    Science.gov (United States)

    Bharti, Vishal; Sharma, Abhishek; Gupta, Vinay; Sharma, Gauri D.; Chand, Suresh

    2016-02-01

    Here we report, the charge transport properties of polymer-polymer dual donor blended film, viz., polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) and poly [N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'benzothiadiazole) (PCDTBT) in the optimized concentration. Trap density and hole mobility in polymer-polymer (PTB7-PCDTBT) dual donor system have been studied by means of current density-voltage (J-V) characteristics at various temperatures, i.e., 280 K-120 K in hole only device configuration, i.e., indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT:PSS)/Polymer film/gold (Au). The J-V curves exhibit the space charge limited conduction behavior. The corresponding hole mobility for PTB7 and PCDTBT are 3.9 × 10-4 cm2 V-1 s-1 and 2.1 × 10-4 cm2 V-1 s-1, respectively, whereas it is 9.1 × 10-4 cm2 V-1 s-1 in the polymer-polymer blend of PTB7:PCDTBT (0.7:0.3). This enhancement in mobility can be attributed to the suppressed trap density in PTB7:PCDTBT (0.7:0.3) of 7.4 × 1016 cm-3, as compared to the trap density of 1.1 × 1017 cm-3 for PTB7 and 1.6 × 1017 cm-3 for PCDTBT. Atomic force microscopy shows an improvement in the morphology of the blend. The J-V characteristic at various light intensities in the bulk heterojunction (BHJ) solar cell reveals that the blending of PCDTBT in PTB7 suppressed the trap-assisted recombination. The corresponding power conversion efficiencies for PTB7:PC71BM, PCDTBT:PC71BM and PTB7:PCDTBT:PC71BM BHJ solar cells are 6.9%, 6.1% and 9.0%, respectively. This work unravels that the enhanced mobility and suppressed trap density play a significant role in the improvement of efficiency in dual donor based organic solar cells.

  4. Inverted organic solar cells using a solution-processed TiO2/CdSe electron transport layer to improve performance

    Science.gov (United States)

    Ma, Xiaoxiao; Xiong, Zhicheng; Wang, Wen; Zhang, Luming; Wu, Sujuan; Lu, Xubing; Gao, Xingsen; Shui, Lingling; Liu, Jun-Ming

    2016-04-01

    In the present work, cadmium selenide (CdSe) nanoparticles are deposited directly on TiO2 film to fabricate the TiO2/CdSe interlayer by a chemical bath deposition method. The inverted organic solar cells using poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk heterojunction as an active layer and TiO2/CdSe interlayer as an electron transport layer (ETL) are fabricated in air. A series of microstructural, photo-electronic, and electrochemical characterizations on these cells are performed. The TiO2/CdSe structure with respect to either the TiO2 layer or the CdSe layer as the ETL exhibits significantly enhanced external quantum efficiency (EQE) in the visible region. The photoluminescence (PL) measurement shows that the exciton dissociation in the TiO2/CdSe structure is more effective than that in either the TiO2 or CdSe structure. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) implies that the charge recombination in the TiO2/CdSe structure can be suppressed with respect to that in either the CdSe or TiO2 structure. The photovoltaic performances of the cells with the TiO2/CdSe ETL are clearly improved compared with the reference cells only with the TiO2 layer or CdSe layer as the ETL.

  5. Solar electron source and thermionic solar cell

    Directory of Open Access Journals (Sweden)

    Parham Yaghoobi

    2012-12-01

    Full Text Available Common solar technologies are either photovoltaic/thermophotovoltaic, or use indirect methods of electricity generation such as boiling water for a steam turbine. Thermionic energy conversion based on the emission of electrons from a hot cathode into vacuum and their collection by an anode is also a promising route. However, thermionic solar conversion is extremely challenging as the sunlight intensity is too low for heating a conventional cathode to thermionic emission temperatures in a practical manner. Therefore, compared to other technologies, little has been done in this area, and the devices have been mainly limited to large experimental apparatus investigated for space power applications. Based on a recently observed “Heat Trap” effect in carbon nanotube arrays, allowing their efficient heating with low-power light, we report the first compact thermionic solar cell. Even using a simple off-the-shelf focusing lens, the device delivered over 1 V across a load. The device also shows intrinsic storage capacity.

  6. Morphology control of polymer: Fullerene solar cells by nanoparticle self-assembly

    Science.gov (United States)

    Zhang, Wenluan

    During the past two decades, research in the field of polymer based solar cells has attracted great effort due to their simple processing, mechanical flexibility and potential low cost. A standard polymer solar cell is based on the concept of a bulk-heterojunction composed of a conducting polymer as the electron donor and a fullerene derivative as the electron acceptor. Since the exciton lifetime is limited, this places extra emphasis on control of the morphology to obtain improved device performance. In this thesis, detailed characterization and novel morphological design of polymer solar cells was studied, in addition, preliminary efforts to transfer laboratory scale methods to industrialized device fabrication was made. Magnetic contrast neutron reflectivity was used to study the vertical concentration distribution of fullerene nanoparticles within poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b]thiophene (pBTTT) thin film. Due to the wide space between the side chains of polymer, these fullerene nanoparticles intercalate between them creating a stable co-crystal structure. Therefore, a high volume fraction of fullerene was needed to obtain optimal device performance as phase separated conductive pathways are required and resulted in a homogeneous fullerene concentration profile through the film. Small angle neutron scattering was used to find there is amorphous fullerene even at lower concentration since it was previously believed that all fullerene formed a co-crystal. These fullerene molecules evolve into approximately 15 nm sized agglomerates at higher concentrations to improve electron transport. Unfortunately, thermal annealing gives these agglomerates mobility to form micrometer sized crystals and reduce the device performance. In standard poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCMBM) solar cells, a higher concentration of PCBM at the cathode interface is desired due to the band alignment structure. This was

  7. Simple Calculation of Power Conversion Efficiency of PC61BM and PC71 BM Based Organic Solar Cells--Good Agreement with Experiments in Donor Materials with Different Band Gap Energies.

    Science.gov (United States)

    Otsura, Takanori; Nakatsuka, Emi; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

    2016-04-01

    The power conversion efficiencies (PCEs) as a function of band gap energies and the lowest unoccupied molecular orbital (LUMO) levels of donor materials are studied in bulk-heterojunction organic solar cells (OSCs) fabricated from donor materials and fullerene acceptors. The PCEs of [6,6]-pheynl-C61-butyric acid methyl ester (PC61BM) and [6,6]-pheynl-C71-butyric acid methyl ester (PC71 BM) based OSCs blended with donor materials under the Air Mass 1.5 (AM1.5) spectrum are calculated. In the calculation, the short circuit current densities are determined by band gap energies of donor materials and the open circuit voltages are derived from the difference between the highest occupied molecular orbital (HOMO) levels of donor materials and LUMO levels of PC61BM and PC71 BM. The calculation is in good agreement with the experiments. The PCEs under a fluorescent lamp are also calculated. The calculated PCEs of PC71 BM based OSCs under a fluorescent lamp are higher than those under the AM1.5 spectrum by a factor of 2. The PCEs of thieno [3,4-b] thiophene and benzodithiophene (PTB7):PC71BM based OSCs are studied under the AM1.5 spectrum and a fluorescent lamp spectrum and are consistent with the calculation. PMID:27451630

  8. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    International Nuclear Information System (INIS)

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs. (paper)

  9. Charge separation in organic solar cells: Effects of Coulomb interaction, recombination and hole propagation

    Science.gov (United States)

    Nemati Aram, Tahereh; Asgari, Asghar; Mayou, Didier

    2016-07-01

    Bulk heterojunction (BHJ) organic photovoltaic cells are analysed within a simple efficient model that includes the important physical properties of such photovoltaic systems. In this model, in contrast with most of the previous studies, we take into account the motion of both the electron and the hole in the separation process at the donor-acceptor interface. We theoretically examine the exciton dissociation yield under the influences of charge Coulomb interaction and non-radiative recombination. We find that the electron-hole local Coulomb attraction and charge carriers' coupling parameters play an important role in the system performance and in the optimal energy conversion efficiency of the BHJ photocell. We show that the fixed-hole models tend to underestimate the yield.

  10. Application of Multifunctional and Crosslinkable Materials in Polymer Solar Cells%多功能可交联材料在聚合物太阳能电池中的应用

    Institute of Scientific and Technical Information of China (English)

    王维; 周铭露; 梁露英; 王文; 凌启淡

    2013-01-01

    Polymer solar cells ( PSCs) offer great potential for fabrication of large-area, lightweight, and flexible organic solar cells by using low-cost printing and coating technologies. The power-conversion efficiencies have improved from 3% to almost 10% in recent years. Despite the advance on polymer solar cells performance, long-term stability is a primary area of concern for PSCs. However, it is highly challenging to develop PSC that can achieve high PCE while maintaining excellent ambient stability of the device. Recently, crosslinkable materials are widely used in the field of organic optical device, especially in polymer solar cells. Using these materials as donor, acceptor, or for fabrication of ordered bulk heterojunction, the stability and power-conversion efficiencies will be enhanced. And when these materials are applied to electron transport layer and hole transport layer, the power-conversion efficiencies, stability, fill factor, short-circuit current and other parameters will be correspondingly improved simultaneously. In the paper, the influence of crosslinkable materials to photoelectric performance is described in detail according to their diverse functions for polymer solar cells, such as the kind of functional groups, treatment time, temperature, initiator. At the same time, the research progress of crosslinkable materials utilizing as buffer layer or for fabrication of ordered bulk heterojunction polymer solar cell is discussed. Finally, we look forward to its development prospects in this field.%近年来,可交联材料在有机光电器件领域,尤其是聚合物太阳能电池领域,得到了广泛的应用研究.可交联材料作为活性层中的给体材料或受体材料以及制作有序本体异质结聚合物太阳能电池,可以提高器件的稳定性及光电转化效率.可交联材料应用于聚合物太阳能电池的电子传输层或空穴传输层,可以提高器件的开路电压、转化效率、稳定性等各项性能参

  11. New Insights into the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction: A Time-of-Flight Quasi-Elastic Neutron Scattering Study.

    Science.gov (United States)

    Guilbert, Anne A Y; Zbiri, Mohamed; Jenart, Maud V C; Nielsen, Christian B; Nelson, Jenny

    2016-06-16

    The molecular dynamics of organic semiconductor blend layers are likely to affect the optoelectronic properties and the performance of devices such as solar cells. We study the dynamics (5-50 ps) of the poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blend by time-of-flight quasi-elastic neutron scattering, at temperatures in the range 250-360 K, thus spanning the glass transition temperature region of the polymer and the operation temperature of an OPV device. The behavior of the QENS signal provides evidence for the vitrification of P3HT upon blending, especially above the glass transition temperature, and the plasticization of PCBM by P3HT, both dynamics occurring on the picosecond time scale. PMID:27192930

  12. Characterization of multicrystalline solar cells

    International Nuclear Information System (INIS)

    The evaluation and assessment of the performance of photovoltaic (PV) cells in terms of measurable parameters requires the measurement of the current as a function of voltage, temperature, intensity, wind speed and spectrum. Most noticeable of all these parameters in the PV conversion efficiency η, defined as the maximum electrical power Pmax produced by the PV cell divided by the incident photon power Pin which is measured with respect to standard test conditions (Sc). These conditions refer to the spectrum (AM 1.5), solar radiation intensity (1000 Wm-2), cell temperature (25 ± 2 degree C) and wind speed (2 mph). Tests under STC are carried out in the laboratory at a controlled environment. There have been several studies that analyze uncertainties in the laboratory measurement of solar cell efficiencies using different solar simulators and their transference to operational situations. Our preliminary results demonstrate that the short circuit current (ISC) of the solar cell decreases when irradiance is less than 1000 Wm-2 irrespective of the working temperature of the cell

  13. Morphology of polymer solar cells

    DEFF Research Database (Denmark)

    Böttiger, Arvid P.L.

    the morphology of the active layer of the solar cells when produced with water based inks using R2R coating. Using a broad range of scattering and imaging techniques, cells coated with water based inks were investigated, and compared to their spin coated counterpart. Two challenges to be addressed were small...... as a function of polymer, type of ink, annealing etc. Ptychography is a new state of the art X-ray imaging technique based on coherent scattering. Together with Scanning X-ray Transmission Microscopy (STXM) it has been used in this study to inspect the morphology of the active layer taken from working solar...

  14. Solar cell circuit and method for manufacturing solar cells

    Science.gov (United States)

    Mardesich, Nick (Inventor)

    2010-01-01

    The invention is a novel manufacturing method for making multi-junction solar cell circuits that addresses current problems associated with such circuits by allowing the formation of integral diodes in the cells and allows for a large number of circuits to readily be placed on a single silicon wafer substrate. The standard Ge wafer used as the base for multi-junction solar cells is replaced with a thinner layer of Ge or a II-V semiconductor material on a silicon/silicon dioxide substrate. This allows high-voltage cells with multiple multi-junction circuits to be manufactured on a single wafer, resulting in less array assembly mass and simplified power management.

  15. Current-Enhanced Quantum Well Solar Cells

    Institute of Scientific and Technical Information of China (English)

    LOU Chao-Gang; SUN Qiang; XU Jun; ZHANG Xiao-Bing; LEI Wei; WANG Bao-Ping; CHEN Wen-Jun; QIAO Zai-Xiang

    2006-01-01

    We present the experimental results that demonstrate the enhancement of the short-circuit current of quantum well solar cells. The spectral response shows that the introduction of quantum wells extends the absorption spectrum of solar cells. The current densities under different truncated spectrums significantly increase, showing that quantum well solar cells are suitable to be the middle cells of GaInP/GaAs/Ge triple-junction solar cells to increase their overall conversion efficiency.

  16. Spectroscopic investigation of new fullerene based acceptors for organic solar cells; Spektroskopische Untersuchung neuartiger Fullerenakzeptoren fuer organische Solarzellen

    Energy Technology Data Exchange (ETDEWEB)

    Liedte, Moritz Nils

    2012-04-27

    The main topic of my thesis was the optical spectroscopy of accepters for organic bulk-heterojunction polymer-fullerene solar cells in the visible till near-infrared regime. Pure fullerene samples as well as blends of fullerenes with polymers were studied. Additionally measurements regarding the morphology, spin states and solar cell performance were done. The aims were to determine the ability of new molecules as acceptors for organic solar cells, to find and understand the photoinduced absorption signatures of optical excited anions on fullerene bulks of different sizes and finally to learn about the charge carrier generation process in polymer:Lu{sub 3}N rate at C{sub 80} blends and thus understand the origin of the comparable low current density in this devices, about 25 % less than for P3HT:PC{sub 61}BM solar cells. In our publications due to these topics we presented that the novel C{sub 70}-C{sub 70} dimer fullerenes are fine acceptors for polymer:fullerene solar cells, showing a better absorption coefficient around 500 nm than C{sub 60} based acceptors and high singlet-exciton quenching rates. Anion signatures for fullerene molecules of different sizes were clearly found for C{sub 60{sup -}} at 1.18 eV and for C{sub 70{sup -}} at 0.92 eV. Less clear are my findings regarding the signatures for C{sub 80{sup -}} and C{sub 84{sup -}}. Due to the low signal-to-noise ratio in these measurements and some unique properties of the available materials I was only able to indicate a range from 0.7 eV down to 0.4 eV for the optically detected anion signatures of these fullerenes. Still all fullerenes showed a red shift to lower energies for the anion signatures getting stronger the more carbon atoms the fullerenes were made of. The most detailed research in this thesis was done about the Lu{sub 3}N rate at C{sub 80} molecules application as electron acceptor in P3HT:Lu{sub 3}N rate at C{sub 80} solar cells. The use of this acceptor in combination with P3HT lead to a

  17. Synthesis, characterization and processing of cubic iron pyrite nanocrystals in a photovoltaic cell

    International Nuclear Information System (INIS)

    Cubic iron pyrite (fool's gold) nanocrystals with an average diameter of ∼60 nm were grown in an oleylamine ligand which acts as a solvent and surfactant without the utilization of alkyl phosphine and phosphonic acids at 230 °C in a Schlenk flask. For the first time photoluminescence properties of such cubic nanocrystals were analyzed at 77 K, showing band gaps of 1.71 eV. However, UV–Vis spectra shows a band gap of 1.41 eV for the same nanocrystals, close to the direct band gap (1.38 eV) of reported pyrite materials. The discrepancy of 0.3 eV in absorption (UV–Vis) and emission spectra (PL) are attributed to the phonon coupling (stokes shift). The prepared cubic nanocrystals were well suited for an inexpensive thin film solar cells and further processed and spin casted with a synthesized CdSe quantum dots in chloroform solvent as a bulk-heterojunction (BHJ) solar cell in order to get photovoltaic responses in real devices. We successfully report here an efficiency of 0.5% with the JSC of 3.7 mA/cm−2 and VOC of 0.16 mV with a cell structure of ITO/PEDOT:PSS/FeS2:CdSe/Au. The morphology and optoelectronic properties are elucidated by SEM, TEM, TEM-EDS, XRD, micro-Raman spectra, IV curve and micro-PL techniques. - Highlights: • Excellent cubic iron pyrite nanocrystals are synthesized by using an oleylamine ligand. • First time PL spectra were used to measure band gaps of such colloidal cubic nanocrytsals. • Pyrite ink was made in suitable solvent to fabricate practical devices. • A successful 0.5% efficiency is reported in bulk-heterojunction cell with CdSe QDs

  18. Silicon for Solar Cells

    OpenAIRE

    Søiland, Anne Karin

    2005-01-01

    This thesis work consists of two parts, each with a different motivation. Part II is the main part and was partly conducted in industry, at ScanWafer ASA’s plant no.2 in Glomfjord.The large growth in the Photo Voltaic industry necessitates a dedicated feedstock for this industry, a socalled Solar Grade (SoG) feedstock, since the currently used feedstock rejects from the electronic industry can not cover the demand. Part I of this work was motivated by this urge for a SoG- feedstock. It was a ...

  19. Organic and hybrid solar cells

    CERN Document Server

    Huang, Hui

    2014-01-01

    This book delivers a comprehensive evaluation of organic and hybrid solar cells and identifies their fundamental principles and numerous applications. Great attention is given to the charge transport mechanism, donor and acceptor materials, interfacial materials, alternative electrodes, device engineering and physics, and device stability. The authors provide an industrial perspective on the future of photovoltaic technologies.

  20. Fullerene based organic solar cells

    NARCIS (Netherlands)

    Popescu, Lacramioara Mihaela

    2008-01-01

    The direct conversion of the sunlight into electricity is the most elegant process to generate environmentally-friendly renewable energy. Plastic solar cells offer the prospect of flexible, lightweight, lower cost of manufacturing, and hopefully an efficient way to produce electricity from sunlight.

  1. Solar-Cell Slide Rule

    Science.gov (United States)

    Yamakawa, K. A.

    1983-01-01

    Slide rule relates efficiency, impurity types, impurity concentrations, and process types. Solar cell slide rule calculations are determination of allowable impurity concentration for nonredistributive process, determination of impurity buildup factor for redistributive process and determination of allowable impurity concentration for redistributive process.

  2. Nanowire-based All Oxide Solar Cells

    OpenAIRE

    Yang, Peidong

    2009-01-01

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is ...

  3. Electromagnetic approach to ultrathin solar cell efficiencies

    OpenAIRE

    Niv, A.; Gharghi, M.; Abrams, Z. R.; Gladden, C.; Zhang, X.

    2011-01-01

    Current methods for evaluating solar cell efficiencies cannot be applied to extremely thin cells where phenomena from the realm of near field optics prevail. We overcome this problem by offering a rigorous electromagnetic calculation of solar cell efficiencies based on the fluctuation dissipation theorem. Our approach is demonstrated by calculating the efficiency of a GaAs solar cell with an Au back reflector for thicknesses well below the typical wavelength of the solar flux. It is shown tha...

  4. Perovskite solar cells: an emerging photovoltaic technology

    OpenAIRE

    Nam-Gyu Park

    2015-01-01

    Perovskite solar cells based on organometal halides represent an emerging photovoltaic technology. Perovskite solar cells stem from dye-sensitized solar cells. In a liquid-based dye-sensitized solar cell structure, the adsorption of methylammonium lead halide perovskite on a nanocrystalline TiO2 surface produces a photocurrent with a power conversion efficiency (PCE) of around 3–4%, as first discovered in 2009. The PCE was doubled after 2 years by optimizing the perovskite coating conditions....

  5. Key Physical Mechanisms in Nanostructured Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Dr Stephan Bremner

    2010-07-21

    The objective of the project was to study both theoretically and experimentally the excitation, recombination and transport properties required for nanostructured solar cells to deliver energy conversion efficiencies well in excess of conventional limits. These objectives were met by concentrating on three key areas, namely, investigation of physical mechanisms present in nanostructured solar cells, characterization of loss mechanisms in nanostructured solar cells and determining the properties required of nanostructured solar cells in order to achieve high efficiency and the design implications.

  6. Solar cells in abundance

    International Nuclear Information System (INIS)

    This article takes a look at the rapidly growing market for photovoltaic systems and the production facilities needed to meet increasing demands. Trends in the construction of manufacturing facilities are quoted as showing that facilities will be attaining a similar size to that found in the automotive industry. The author quotes that production capacities are growing much faster than market demands and that prices on the market are not competitive with other electricity prices. Markets with strong growth are noted, as are others with high administrative impediments and resulting slower growth of installed power. Reduced governmental funding in Germany is commented on. Also, the availability of sufficient silicon is examined. The pressure on costs is considered as being positive, as sinking costs will soon make solar power more competitive on the power market.

  7. Film adhesion in amorphous silicon solar cells

    Indian Academy of Sciences (India)

    A R M Yusoff; M N Syahrul; K Henkel

    2007-08-01

    A major issue encountered during fabrication of triple junction -Si solar cells on polyimide substrates is the adhesion of the solar cell thin films to the substrates. Here, we present our study of film adhesion in amorphous silicon solar cells made on different polyimide substrates (Kapton VN, Upilex-S and Gouldflex), and the effect of tie coats on film adhesion.

  8. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  9. Research of commercial bifacial silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Tiantian; Li, Hongbo [Shanghai Solar Energy Research Center (China); Li, Wennan; Guo, Wenlin [Shanghai Perfect Energy (China); Chen, Mingbo [Shanghai Institute of Space Power-Sources (China)

    2008-07-01

    Because of the special finger shape and junction structure, bifacial silicon solar cells could receive sunlight from both sides. So the cells can absorb much sunlight, have less strict require for installation, and have higher conversion efficiency. We have done research in commercial bifacial silicon solar cells. We designed the bifacial silicon solar cells with realizable structure and high conversion efficiency. We designed and realized proper technics path, which are used to fabricate these bifacial solar cells. The boron backfield is used. The anti-reflection coating and finger contact are fabricated on both surfaces of the solar cells, so the cells have different contact structure. Meanwhile, we realized ohmic contact between finger contacts and surface of solar cells on both sides. We successfully produced the bifacial silicon solar cells with the front and rear efficiencies exceed 15% and 9%(AM1.5, 25 C), respectively, and which can be produced in large-scale. (orig.)

  10. Quality control of roll-to-roll processed polymer solar modules by complementary imaging methods

    DEFF Research Database (Denmark)

    Rösch, R.; Krebs, Frederik C; Tanenbaum, D.M.; Hoppe, H.

    2012-01-01

    We applied complementary imaging methods to investigate processing failures of roll-to-roll solution processed polymer solar modules based on polymer:fullerene bulk heterojunctions. For investigation of processing deficiencies in solar modules we employed dark lock-in thermography (DLIT), electro...... investigation can be divided into a fast DLIT overview of the module and a successive more detailed analysis of the suspicious region by all imaging methods....

  11. INCREMENT OF EFFICIENCY OF SOLAR CELL, WITH CHANGE SHAPE AND SIZE OF SOLAR PENNAL

    OpenAIRE

    S.K. Yadav; K.L. Yadav

    2014-01-01

    -To increase the efficiency of solar system with the help of change shape and size of solar pennal and arrangement of solar cell. And falling of light energy absorbed by solar cells and also dependence of solar energy, efficiency of solar cell on the multireflections of light on the solar cells. We formed different-different shape and size of solar pennal efficiency of solar cell, the internal and external reflections of light occurs many times with high energetic beam of ligh...

  12. High Efficiency Polymer Solar Cells Technologies

    Institute of Scientific and Technical Information of China (English)

    Abdrhman M G; LI Hang-quan; ZHANG Li-ye; ZHOU Bing

    2006-01-01

    The conjugated polymer-based solar cell is one of the most promising devices in search of sustainable, renewable energy sources in last decade. It is the youngest field in organic solar cell research and also is certainly the fastest growing one at the moment. In addition, the key factor for polymer-based solar cells with high-efficiency is to invent new materials. Organic solar cell has attracted significant researches and commercial interest due to its low cost in fabrication and flexibility in applications. However, they suffer from relatively low conversion efficiency. The summarization of the significance and concept of high efficiency polymer solar cell technologies are presented.

  13. Hybrid emitter all back contact solar cell

    Science.gov (United States)

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

  14. Three-Terminal Amorphous Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Cheng-Hung Tai

    2011-01-01

    Full Text Available Many defects exist within amorphous silicon since it is not crystalline. This provides recombination centers, thus reducing the efficiency of a typical a-Si solar cell. A new structure is presented in this paper: a three-terminal a-Si solar cell. The new back-to-back p-i-n/n-i-p structure increased the average electric field in a solar cell. A typical a-Si p-i-n solar cell was also simulated for comparison using the same thickness and material parameters. The 0.28 μm-thick three-terminal a-Si solar cell achieved an efficiency of 11.4%, while the efficiency of a typical a-Si p-i-n solar cell was 9.0%. Furthermore, an efficiency of 11.7% was achieved by thickness optimization of the three-terminal solar cell.

  15. Studies of Inverted Organic Solar Cells Fabricated by Doctor Blading Technique

    OpenAIRE

    Tang, Zheng

    2010-01-01

    Over the last few decades, bulk-heterojunction organic photovoltaic devices comprising an intimately mixed donor-acceptor blend have gained serious attention due to their potential for being cheap, light weight, flexible and environmentally friendly. In this thesis, APFO-3/PCBM bulk-heterojunction based organic photovoltaic devices with an inverted layer sequence were investigated systematically. Doctor blade coating is a technique that is roll-to-roll compatible and cost efficient and has be...

  16. Increasing the efficiency of organic solar cells by photonic and electrostatic-field enhancements

    Energy Technology Data Exchange (ETDEWEB)

    Nalwa, Kanwar [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    recombination of charge carriers. Thus it becomes imperative to understand the effect of processing conditions such as spin coating speed and drying rate on defect density and hence induced carrier recombination mechanism. In this study, It is shown that slow growth (longer drying time) of the active-layer leads to reduction of sub-bandgap traps by an order of magnitude as compared to fast grown active-layer. By coupling the experimental results with simulations, it is demonstrated that at one sun condition, slow grown device has bimolecular recombination as the major loss mechanism while in the fast grown device with high trap density, the trap assisted recombination dominates. It has been estimated that non-radiative recombination accounts nearly 50% of efficiency loss in modern OPVs. Generally, an external bias (electric field) is required to collect all the photogenerated charges and thus prevent their recombination. The motivation is to induce additional electric field in otherwise low mobility conjugated polymer based active layer by incorporating ferroelectric dipoles. This is expected to facilitate singlet exciton dissociation in polymer matrix and impede charge transfer exciton (CTE) recombination at polymer:fullerene interface. For the first time, it is shown that the addition of ferroelectric dipoles to modern bulk heterojunction (BHJ) can significantly improve exciton dissociation, resulting in a ~50% enhancement of overall solar cell efficiency. The devices also exhibit the unique ferroelectric-photovoltaic effect with polarization-controlled power conversion efficiency.

  17. Silicon Carbide Solar Cells Investigated

    Science.gov (United States)

    Bailey, Sheila G.; Raffaelle, Ryne P.

    2001-01-01

    The semiconductor silicon carbide (SiC) has long been known for its outstanding resistance to harsh environments (e.g., thermal stability, radiation resistance, and dielectric strength). However, the ability to produce device-quality material is severely limited by the inherent crystalline defects associated with this material and their associated electronic effects. Much progress has been made recently in the understanding and control of these defects and in the improved processing of this material. Because of this work, it may be possible to produce SiC-based solar cells for environments with high temperatures, light intensities, and radiation, such as those experienced by solar probes. Electronics and sensors based on SiC can operate in hostile environments where conventional silicon-based electronics (limited to 350 C) cannot function. Development of this material will enable large performance enhancements and size reductions for a wide variety of systems--such as high-frequency devices, high-power devices, microwave switching devices, and high-temperature electronics. These applications would supply more energy-efficient public electric power distribution and electric vehicles, more powerful microwave electronics for radar and communications, and better sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. The 6H-SiC polytype is a promising wide-bandgap (Eg = 3.0 eV) semiconductor for photovoltaic applications in harsh solar environments that involve high-temperature and high-radiation conditions. The advantages of this material for this application lie in its extremely large breakdown field strength, high thermal conductivity, good electron saturation drift velocity, and stable electrical performance at temperatures as high as 600 C. This behavior makes it an attractive photovoltaic solar cell material for devices that can operate within three solar radii of the Sun.

  18. Work Station For Inverting Solar Cells

    Science.gov (United States)

    Feder, H.; Frasch, W.

    1982-01-01

    Final work station along walking-beam conveyor of solar-array assembly line turns each pretabbed solar cell over, depositing it back-side-up onto landing pad, which centers cell without engaging collector surface. Solar cell arrives at inverting work station collector-side-up with two interconnect tabs attached to collector side. Cells are inverted so that second soldering operation takes place in plain view of operator. Inversion protects collector from damage when handled at later stages of assembly.

  19. Perovskite Solar Cells:Work Mechanism and Major Factors Affecting Their Performances%钙钛矿太阳电池的工作机理及性能的主要影响因素

    Institute of Scientific and Technical Information of China (English)

    钱柳; 丁黎明

    2015-01-01

    本文综合评述了钙钛矿太阳电池的重要研究成果,解释了其工作机理并总结了影响电池性能的关键因素:钙钛矿化学组成、结晶与形貌、传输层、电极和体异质结等。对钙钛矿太阳电池的未来发展进行了展望。%Hybrid organic-inorganic perovskites were first introduced to photovoltaic community in 2009 . In subsequent years, the power conversion efficiency has increased from 3. 8% to ~20%, leaving dye-sensitized solar cells and bulk-heterojunction solar cells far behind. “Perovskite” is a crystal possessing the same crystal structure as calcium titanate, namely, ABX3 . Perovskites have unique properties, like broad absorption spec-tra, high absorption coefficient, ambipolar charge transport, long exciton lifetime and very low binding energy of exciton. Currently, the architecture of perovskite solar cells has been simplified from meso-structured solar cells to planar-heterojunction solar cells, getting closer to the low-cost, high-efficiency target for practical application. Many innovative researches are pushing the application of this new photovoltaic material to the cli-max . This review summarizes the working mechanism of perovskite solar cells and expounds several key factors affecting device performance, i. e. components, crystallization and morphology, transport layers, electrode materials and planted bulk-heterojunction. However, we should note that perovskites have some drawbacks im-peding its commercialization. Perovskites are sensitive to oxygen and water vapor, making the solar cells un-stable in the ambient;it is challenging to prepare large films because the morphology of perovskite film is diffi-cult to control;the use of the toxic metal, lead, will also undermine the credit earned by their outstanding photovoltaic performance. It is very important for us to understand those mechanism and factors affecting de-vice performance, and to find approaches to deal with instability

  20. Supramolecular photochemistry and solar cells

    Directory of Open Access Journals (Sweden)

    IHA NEYDE YUKIE MURAKAMI

    2000-01-01

    Full Text Available Supramolecular photochemistry as well as solar cells are fascinating topics of current interest in Inorganic Photochemistry and very active research fields which have attracted wide attention in last two decades. A brief outline of the investigations in these fields carried out in our Laboratory of Inorganic Photochemistry and Energy Conversion is given here with no attempt of an exhaustive coverage of the literature. The emphasis is placed on recent work and information on the above mentioned subjects. Three types of supramolecular systems have been the focus of this work: (i cage-type coordination compounds; (ii second-sphere coordination compounds, exemplified by ion-pair photochemistry of cobalt complexes and (iii covalently-linked systems. In the latter, modulation of the photoluminescence and photochemistry of some rhenium complexes are discussed. Solar energy conversion and development of thin-layer photoelectrochemical solar cells based on sensitization of nanocrystalline semiconductor films by some ruthenium polypyridyl complexes are presented as an important application that resulted from specifically engineered artificial assemblies.