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Sample records for cigs thin-film solar

  1. Printable CIGS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Fan, Xiaojuan

    2013-03-01

    Among the various thin film solar cells in the market, CuInGaSe thin film solar cells have been considered as the most promising alternatives to crystalline silicon solar cells because of their high photo-electricity conversion efficiency, reliability, and stability. However, many fabrication methods of CIGS thin film are based on vacuum processes such as evaporation and sputtering techniques which are not cost efficient. This work develops a solution method using paste or ink liquid spin-coated on glass that would be competitive to conventional ways in terms of cost effective, non-vacuum needed, and quick processing. A mixture precursor was prepared by dissolving appropriate amounts of composition chemicals. After the mixture solution was cooled, a viscous paste was prepared and ready for spin-coating process. A slight bluish CIG thin film on substrate was then put in a tube furnace with evaporation of metal Se followed by depositing CdS layer and ZnO nanoparticle thin film coating to complete a solar cell fabrication. Structure, absorption spectrum, and photo-electricity conversion efficiency for the as-grown CIGS thin film solar cell are under study.

  2. Printable CIGS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Fan, Xiaojuan

    2014-03-01

    Among the various thin film solar cells in the market, CuInGaSe thin film cells have been considered as the most promising alternatives to silicon solar cells because of their high photo-electricity efficiency, reliability, and stability. However, many fabrication of CIGS thin film are based on vacuum processes such as evaporation sputtering techniques which are not cost efficient. This work develops a method using paste or ink liquid spin-coated on glass that would be to conventional ways in terms of cost effective, non-vacuum needed, quick processing. A mixture precursor was prepared by dissolving appropriate amounts of chemicals. After the mixture solution was cooled, a viscous paste prepared and ready for spin-coating process. A slight bluish CIG thin film substrate was then put in a tube furnace with evaporation of metal Se by depositing CdS layer and ZnO nanoparticle thin film coating to a solar cell fabrication. Structure, absorption spectrum, and photo-conversion efficiency for the as-grown CIGS thin film solar cell under study.

  3. Electrical impact of MoSe2 on CIGS thin-film solar cells.

    PubMed

    Hsiao, Kuo-Jui; Liu, Jing-Da; Hsieh, Hsing-Hua; Jiang, Ting-Shiuan

    2013-11-07

    The CIGS solar cell is one of the most promising photovoltaic devices due to the achievement of the highest conversion efficiency (>20%) among all thin-film solar cells. The CIGS cell has a glass/Mo/CIGS/CdS/TCO configuration, and the CIGS-Mo interface is a Schottky barrier to holes. During the sulfurization-after-selenization (SAS) CIGS formation process with H2Se gas, the Mo surface transforms naturally into MoSe2 at the CIGS-Mo interface. In this work, the electrical impact of MoSe2 on CIGS solar cells was investigated. Different CIGS-Mo interfaces were prepared with two CIGS processes. One is SAS, and the other is the sequential-sputtering-selenization CIGS process with Se gas. Formation of MoSe2 is hardly observed in the latter process. Samples were characterized by XRD, the van der Pauw method, reflectance, and visual inspection. Besides, Schottky barrier heights of cells were extracted from J-V-T measurements. For the first time, it was experimentally shown that the existence of thin MoSe2 film can decrease the apparent Schottky barrier height of CIGS solar cells. In addition, 1-dimensional numerical simulation showed that a larger barrier height affects both the fill factor and open-circuit voltage. Therefore, the formation of MoSe2 during the CIGS process should minimize the negative effect of Schottky barrier on solar-cell performances, especially with large Schottky barrier.

  4. High efficiency copper indium gallium diselenide (CIGS) thin film solar cells

    NASA Astrophysics Data System (ADS)

    Rajanikant, Ray Jayminkumar

    The generation of electrical current from the solar radiation is known as the photovoltaic effect. Solar cell, also known as photovoltaic (PV) cell, is a device that works on the principle of photovoltaic effect, and is widely used for the generation of electricity. Thin film polycrystalline solar cells based on copper indium gallium diselenide (CIGS) are admirable candidates for clean energy production with competitive prices in the near future. CIGS based polycrystalline thin film solar cells with efficiencies of 20.3 % and excellent temperature stability have already been reported at the laboratory level. The present study discusses about the fabrication of CIGS solar cell. Before the fabrication part of CIGS solar cell, a numerical simulation is carried out using One-Dimensional Analysis of Microelectronic and Photonic Structures (AMPS-ID) for understanding the physics of a solar cell device, so that an optimal structure is analyzed. In the fabrication part of CIGS solar cell, Molybdenum (Mo) thin film, which acts as a 'low' resistance metallic back contact, is deposited by RF magnetron sputtering on organically cleaned soda lime glass substrate. The major advantages for using Mo are high temperature, (greater than 600 °C), stability and inertness to CIGS layer (i.e., no diffusion of CIGS into Mo). Mo thin film is deposited at room temperature (RT) by varying the RF power and the working pressure. The Mo thin films deposited with 100 W RF power and 1 mTorr working pressure show a reflectivity of above average 50 % and the low sheet resistance of about 1 O/□. The p-type CIGS layer is deposited on Mo. Before making thin films of CIGS, a powder of CIGS material is synthesized using melt-quenching method. Thin films of CIGS are prepared by a single-stage flash evaporation process on glass substrates, initially, for optimization of deposition parameters and than on Mo coated glass substrates for device fabrication. CIGS thin film is deposited at 250 °C at a

  5. Laser scribing of CIGS thin-film solar cell on flexible substrate

    NASA Astrophysics Data System (ADS)

    Hwang, David J.; Kuk, Seungkuk; Wang, Zhen; Fu, Shi; Zhang, Tao; Kim, Gayeon; Kim, Won Mok; Jeong, Jeung-hyun

    2017-01-01

    Laser scribing technology has been actively developed for thin-film solar cell fabrication taking a number of advantages over mechanical scribing. Its non-contact processing nature enables reliable and precise scribing processes. In particular, it is almost unavoidable to use laser scribing method for fabricating high-quality flexible thin-film solar cells. Despite the fundamental merits that laser scribing can offer, still a number of challenges should be addressed in order to replace the mechanical counterpart for wider range of thin-film solar cells. In this study, we explore optimal laser scribing conditions for copper-indium-gallium-selenide (CIGS) thin-film solar cells, especially based on flexible polyimide (PI) substrate in close comparison with that based on soda-lime glass substrate. Picosecond-pulsed laser of repetition rate up to 100 kHz and wavelength of 532 nm ( 12 ps temporal pulse width) was mainly tested, and scribing speed in the range of 0.01-1 m/s was examined with a few different laser focal spot diameters (27, 34, and 62 μm). Main focus of this study is in understanding distinct laser scribing mechanisms for flexible substrate configurations, thereby finding out intrinsic optimal processing parameters. One of the most critical requirements is to prevent possible damage or deformation of underlying thin-film layer(s) or PI substrate. Effect of microstructures of thin films (in particular, Mo and CIGS) on the scribing behavior was also examined. In order to further improve the performance of the scribing process and reduce the laser power budget as well, mild gas injection scheme was tested.

  6. CIGS2 Thin-Film Solar Cells on Flexible Foils for Space Power

    NASA Technical Reports Server (NTRS)

    Dhere, Neelkanth G.; Ghongadi, Shantinath R.; Pandit, Mandar B.; Jahagirdar, Anant H.; Scheiman, David

    2002-01-01

    CuIn(1-x)Ga(x)S2 (CIGS2) thin-film solar cells are of interest for space power applications because of the near optimum bandgap for AM0 solar radiation in space. CIGS2 thin film solar cells on flexible stainless steel (SS) may be able to increase the specific power by an order of magnitude from the current level of 65 Wkg(sup -1). CIGS solar cells are superior to the conventional silicon and gallium arsenide solar cells in the space radiation environment. This paper presents research efforts for the development of CIGS2 thin-film solar cells on 127 micrometers and 20 micrometers thick, bright-annealed flexible SS foil for space power. A large-area, dual-chamber, inline thin film deposition system has been fabricated. The system is expected to provide thickness uniformity of plus or minus 2% over the central 5" width and plus or minus 3% over the central 6" width. During the next phase, facilities for processing larger cells will be acquired for selenization and sulfurization of metallic precursors and for heterojunction CdS layer deposition both on large area. Small area CIGS2 thin film solar cells are being prepared routinely. Cu-rich Cu-Ga/In layers were sputter-deposited on unheated Mo-coated SS foils from CuGa (22%) and In targets. Well-adherent, large-grain Cu-rich CIGS2 films were obtained by sulfurization in a Ar: H2S 1:0.04 mixture and argon flow rate of 650 sccm, at the maximum temperature of 475 C for 60 minutes with intermediate 30 minutes annealing step at 120 C. Samples were annealed at 500 C for 10 minutes without H2S gas flow. The intermediate 30 minutes annealing step at 120 C was changed to 135 C. p-type CIGS2 thin films were obtained by etching the Cu-rich layer segregated at the surface using dilute KCN solution. Solar cells were completed by deposition of CdS heterojunction partner layer by chemical bath deposition, transparent-conducting ZnO/ZnO: Al window bilayer by RF sputtering, and vacuum deposition of Ni/Al contact fingers through metal

  7. Designing novel thin film polycrystalline solar cells for high efficiency: sandwich CIGS and heterojunction perovskite

    NASA Astrophysics Data System (ADS)

    Wang, Tianyue; Chen, Jiewei; Wu, Gaoxiang; Song, Dandan; Li, Meicheng

    2017-01-01

    Heterojunction and sandwich architectures are two new-type structures with great potential for solar cells. Specifically, the heterojunction structure possesses the advantages of efficient charge separation but suffers from band offset and large interface recombination; the sandwich configuration is favorable for transferring carriers but requires complex fabrication process. Here, we have designed two thin-film polycrystalline solar cells with novel structures: sandwich CIGS and heterojunction perovskite, referring to the advantages of the architectures of sandwich perovskite (standard) and heterojunction CIGS (standard) solar cells, respectively. A reliable simulation software wxAMPS is used to investigate their inherent characteristics with variation of the thickness and doping density of absorber layer. The results reveal that sandwich CIGS solar cell is able to exhibit an optimized efficiency of 20.7%, which is much higher than the standard heterojunction CIGS structure (18.48%). The heterojunction perovskite solar cell can be more efficient employing thick and doped perovskite films (16.9%) than these typically utilizing thin and weak-doping/intrinsic perovskite films (9.6%). This concept of structure modulation proves to be useful and can be applicable for other solar cells. Project supported by the National High-Tech R&D Program of China (No. 2015AA034601), the National Natural Science Foundation of China (Nos. 91333122, 61204064, 51202067, 51372082, 51402106, 11504107), the Ph.D. Programs Foundation of Ministry of Education of China (Nos. 20120036120006, 20130036110012), the Par-Eu Scholars Program, and the Fundamental Research Funds for the Central Universities.

  8. Structural, Electrical, and Optical Properties of ZnO Film Used as Buffer Layer for CIGS Thin-Film Solar Cell.

    PubMed

    Choi, Eun Chang; Cha, Ji-Hyun; Jung, Duk-Young; Hong, Byungyou

    2016-05-01

    The CuIn(x)Ga(1-x)Se2 (CIGS) using the solution-based fabrication method is attractive for thin film solar cells because of its possibilities for large-area and low-cost production. ZnO films between transparent conductive oxide (TCO) and the CdS films can improve the performances of CIGS thin-film solar cells. In this study, we investigated the characteristics of ZnO film between TCO and CIGS layers in a solar cell (AZO/ZnO/CdS/CIGS/Mo), which were deposited at various thicknesses to investigate the role of the films in CIGS solar cells. It was confirmed that the conversion efficiency of a CIGS solar cell depends on the ZnO film. For a ZnO film thickness of 80 nm, the highest power conversion efficiency that a solar cell achieved was J(sc) of 18.73 mA/cm2.

  9. CIGS thin-film solar module processing: case of high-speed laser scribing

    NASA Astrophysics Data System (ADS)

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; de Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-01

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated – ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities.

  10. CIGS thin-film solar module processing: case of high-speed laser scribing.

    PubMed

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; De Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-13

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated - ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities.

  11. CIGS thin-film solar module processing: case of high-speed laser scribing

    PubMed Central

    Gečys, Paulius; Markauskas, Edgaras; Nishiwaki, Shiro; Buecheler, Stephan; De Loor, Ronny; Burn, Andreas; Romano, Valerio; Račiukaitis, Gediminas

    2017-01-01

    In this paper, we investigate the laser processing of the CIGS thin-film solar cells in the case of the high-speed regime. The modern ultra-short pulsed laser was used exhibiting the pulse repetition rate of 1 MHz. Two main P3 scribing approaches were investigated – ablation of the full layer stack to expose the molybdenum back-contact, and removal of the front-contact only. The scribe quality was evaluated by SEM together with EDS spectrometer followed by electrical measurements. We also modelled the electrical behavior of a device at the mini-module scale taking into account the laser-induced damage. We demonstrated, that high-speed process at high laser pulse repetition rate induced thermal damage to the cell. However, the top-contact layer lift-off processing enabled us to reach 1.7 m/s scribing speed with a minimal device degradation. Also, we demonstrated the P3 processing in the ultra-high speed regime, where the scribing speed of 50 m/s was obtained. Finally, selected laser processes were tested in the case of mini-module scribing. Overall, we conclude, that the top-contact layer lift-off processing is the only reliable solution for high-speed P3 laser scribing, which can be implemented in the future terawatt-scale photovoltaic production facilities. PMID:28084403

  12. On the origin of the spatial inhomogeneity of photoluminescence in thin-film CIGS solar devices

    NASA Astrophysics Data System (ADS)

    El-Hajje, Gilbert; Ory, Daniel; Guillemoles, Jean-François; Lombez, Laurent

    2016-07-01

    In this letter, we investigate the origin of the spatial inhomogeneity of the photoluminescence (PL) intensity maps obtained on thin-film solar cells. Based on a hyperspectral imager setup, we record an absolute map of the quasi-Fermi level splitting Δμ by applying the generalized Planck's law. Then, using scanning confocal microscopy, we perform spatially and time-resolved photoluminescence measurements. This allowed us to quantify and map the micrometric fluctuations of the trapping defect density within these solar cells. Finally, we demonstrate the existence of a direct correlation between the spatial fluctuations of the quasi-Fermi level splitting and the trapping defect density. The latter was found to be correlated with the frequently reported spatially inhomogeneous PL maps of thin-film solar cells. Based on the observed correlation, we can quantify the local losses in quasi-Fermi level splitting induced by the spatial distribution of the trapping defects.

  13. One-pot electrodeposition, characterization and photoactivity of stoichiometric copper indium gallium diselenide (CIGS) thin films for solar cells.

    PubMed

    Harati, Mohammad; Jia, Jia; Giffard, Kévin; Pellarin, Kyle; Hewson, Carly; Love, David A; Lau, Woon Ming; Ding, Zhifeng

    2010-12-14

    Herein we report the one-pot electrodeposition of copper indium gallium diselenide, CuIn(1-x)Ga(x)Se(2) (CIGS), thin films as the p-type semiconductor in an ionic liquid medium consisting of choline chloride/urea eutectic mixture known as Reline. The thin films were characterized by scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman microspectroscopy, and UV-visible spectroscopy. Based on the results of the characterizations, the electrochemical bath recipe was optimized to obtain stoichiometric CIGS films with x between 0.2 and 0.4. The chemical activity and photoreactivity of the optimized CIGS films were found to be uniform using scanning electrochemical microscopy and scanning photoelectrochemical microscopy. Low-cost stoichiometric CIGS thin films in one-pot were successfully fabricated.

  14. High-Efficiency CdTe and CIGS Thin-Film Solar Cells: Highlights and Challenges; Preprint

    SciTech Connect

    Noufi, R.; Zweibel, K.

    2006-05-01

    Thin-film photovoltaic (PV) modules of CdTe and Cu(In,Ga)Se2 (CIGS) have the potential to reach cost-effective PV-generated electricity. These technologies have transitioned from the laboratory to the market place. Pilot production and first-time manufacturing are ramping up to higher capacity and enjoying a flood of venture-capital funding. CIGS solar cells and modules have achieved 19.5% and 13% efficiencies, respectively. Likewise, CdTe cells and modules have reached 16.5% and 10.2% efficiencies, respectively. Even higher efficiencies from the laboratory and from the manufacturing line are only a matter of time. Manufacturing-line yield continues to improve and is surpassing 85%. Long-term stability has been demonstrated for both technologies; however, some failures in the field have also been observed, emphasizing the critical need for understanding degradation mechanisms and packaging options. The long-term potential of the two technologies require R&D emphasis on science and engineering-based challenges to find solutions to achieve targeted cost-effective module performance, and in-field durability. Some of the challenges are common to both, e.g., in-situ process control and diagnostics, thinner absorber, understanding degradation mechanisms, protection from water vapor, and innovation in high-speed processing and module design. Other topics are specific to the technology, such as lower-cost and fast-deposition processes for CIGS, and improved back contact and voltage for CdTe devices.

  15. Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells.

    PubMed

    Pianezzi, Fabian; Reinhard, Patrick; Chirilă, Adrian; Bissig, Benjamin; Nishiwaki, Shiro; Buecheler, Stephan; Tiwari, Ayodhya N

    2014-05-21

    Thin film solar cells with a Cu(In,Ga)Se2 (CIGS) absorber layer achieved efficiencies above 20%. In order to achieve such high performance the absorber layer of the device has to be doped with alkaline material. One possibility to incorporate alkaline material is a post deposition treatment (PDT), where a thin layer of NaF and/or KF is deposited onto the completely grown CIGS layer. In this paper we discuss the effects of PDT with different alkaline elements (Na and K) on the electronic properties of CIGS solar cells. We demonstrate that whereas Na is more effective in increasing the hole concentration in CIGS, K significantly improves the pn-junction quality. The beneficial role of K in improving the PV performance is attributed to reduced recombination at the CdS/CIGS interface, as revealed by temperature dependent J-V measurements, due to a stronger electronically inverted CIGS surface region. Computer simulations with the software SCAPS are used to verify this model. Furthermore, we show that PDT with either KF or NaF has also a distinct influence on other electronic properties of the device such as the position of the N1 signal in admittance spectroscopy and the roll-over of the J-V curve at low temperature. In view of the presented results we conclude that a model based on a secondary diode at the CIGS/Mo interface can best explain these features.

  16. Characterization of Flexible CIGS Thin Film Solar Cells or Stainless Steel with Intrinsic ZnO Diffusion Barriers.

    PubMed

    Kim, Chae-Woong; Kim, Hye Jin; Kim, Jin Hyeok; Jeong, Chaehwan

    2016-05-01

    ZnO diffusion barrier layer was deposited by RF magnetron sputtering by using the same method as intrinsic ZnO layer. The CIGS solar cells were fabricated on stainless steel substrate. The 50-200 nm thin ZnO diffusion barriers effectively reduced the diffusion of Fe and Cr, from stainless steel substrates into the CIGS absorbers. The CIGS solar cells with ZnO diffusion barriers increased the J(sc) and FF, which resulted in an increase of cell efficiency from 5.9% up to 9.06%.

  17. Silicon nitride films as the diffusion barriers for flexible CIGS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Qin, Juan; Li, Aimin; Chen, Zhenyi; Zhao, Lei; Zhang, Xiaoli; Shi, Weimin; Wei, Guangpu

    2011-02-01

    Impurity diffusion from the flexible metal substrate into CIGS absorption layer can remarkably reduce cell performance comparing with conventional glass substrate. A diffusion barrier layer lying between the metal substrate and Mo backcontact layer is required to prevent this spread of impurities. In this paper, a set of Si3+xN4-x barrier layers are grown on stainless steel sheets and alloy foils by the magnetron sputtering under different conditions. The morphological, structural and electrical properties of the samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and I-V measurements. Our results indirectly support good blocking effect of Si3+xN4-x barrier to the metal impurities from the stainless steel substrate.

  18. Electrodeposition of Mg doped ZnO thin film for the window layer of CIGS solar cell

    NASA Astrophysics Data System (ADS)

    Wang, Mang; Yi, Jie; Yang, Sui; Cao, Zhou; Huang, Xiaopan; Li, Yuanhong; Li, Hongxing; Zhong, Jianxin

    2016-09-01

    Mg doped ZnO (ZMO) film with the tunable bandgap can adjust the conduction band offset of the window/chalcopyrite absorber heterointerface to positive to reduce the interface recombination and resulting in an increasement of chalcopyrite based solar cell efficiency. A systematic study of the effect of the electrodeposition potential on morphology, crystalline structure, crystallographic orientation and optical properties of ZMO films was investigated. It is interestingly found that the prepared doped samples undergo a significant morphological change induced by the deposition potential. With negative shift of deposition potential, an obvious morphology evolution from nanorod structrue to particle covered films was observed. A possible growth mechanism for explaining the morphological change is proposed and briefly discussed. The combined optical techniques including absorption, transmission and photoluminescence were used to study the obtained ZMO films deposited at different potential. The sample deposited at -0.9 V with the hexagonal nanorods morphology shows the highest optical transparency of 92%. The photoluminescence spectra reveal that the crystallization of the hexagonal nanorod ZMO thin film deoposited at -0.9 V is much better than the particles covered ZMO thin film. Combining the structural and optical properties analysis, the obtained normal hexagonal nanorod ZMO thin film could potentially be useful in nanostructured chalcopyrite solar cells to improve the device performance.

  19. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    PubMed

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3).

  20. Thin Film CIGS and CdTe Photovoltaic Technologies: Commercialization, Critical Issues, and Applications; Preprint

    SciTech Connect

    Ullal, H. S.; von Roedern, B.

    2007-09-01

    We report here on the major commercialization aspects of thin-film photovoltaic (PV) technologies based on CIGS and CdTe (a-Si and thin-Si are also reported for completeness on the status of thin-film PV). Worldwide silicon (Si) based PV technologies continues to dominate at more than 94% of the market share, with the share of thin-film PV at less than 6%. However, the market share for thin-film PV in the United States continues to grow rapidly over the past several years and in CY 2006, they had a substantial contribution of about 44%, compared to less than 10% in CY 2003. In CY 2007, thin-film PV market share is expected to surpass that of Si technology in the United States. Worldwide estimated projections for CY 2010 are that thin-film PV production capacity will be more than 3700 MW. A 40-MW thin-film CdTe solar field is currently being installed in Saxony, Germany, and will be completed in early CY 2009. The total project cost is Euro 130 million, which equates to an installed PV system price of Euro 3.25/-watt averaged over the entire solar project. This is the lowest price for any installed PV system in the world today. Critical research, development, and technology issues for thin-film CIGS and CdTe are also elucidated in this paper.

  1. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased.

  2. Thin film solar cell workshop

    NASA Technical Reports Server (NTRS)

    Armstrong, Joe; Jeffrey, Frank

    1993-01-01

    A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

  3. Overview and Challenges of Thin Film Solar Electric Technologies

    SciTech Connect

    Ullal, H. S.

    2008-12-01

    In this paper, we report on the significant progress made worldwide by thin-film solar cells, namely, amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). Thin-film photovoltaic (PV) technology status is also discussed in detail. In addition, R&D and technology challenges in all three areas are elucidated. The worldwide estimated projection for thin-film PV technology production capacity announcements are estimated at more than 5000 MW by 2010.

  4. Interaction of ultra-short laser pulses with CIGS and CZTSe thin films

    NASA Astrophysics Data System (ADS)

    Gečys, P.; Markauskas, E.; Dudutis, J.; Račiukaitis, G.

    2014-01-01

    The thin-film solar cell technologies based on complex quaternary chalcopyrite and kesterite materials are becoming more attractive due to their potential for low production costs and optimal spectral performance. As in all thin-film technologies, high efficiency of small cells might be maintained with the transition to larger areas when small segments are interconnected in series to reduce photocurrent and related ohmic losses in thin films. Interconnect formation is based on the three scribing steps, and the use of a laser is here crucial for performance of the device. We present our simulation and experimental results on the ablation process investigations in complex CuIn1- x Ga x Se2 (CIGS) and Cu2ZnSn(S,Se)4 (CZTSe) cell's films using ultra-short pulsed infrared (~1 μm) lasers which can be applied to the damage-free front-side scribing processes. Two types of processes were investigated—direct laser ablation of ZnO:Al/CIGS films with a variable pulse duration of a femtosecond laser and the laser-induced material removal with a picosecond laser in the ZnO:Al/CZTSe structure. It has been found that the pulse energy and the number of laser pulses have a significantly stronger effect on the ablation quality in ZnO:Al/CIGS thin films rather than the laser pulse duration. For the thin-film scribing applications, it is very important to carefully select the processing parameters and use of ultra-short femtosecond pulses does not have a significant advantage compared to picosecond laser pulses. Investigations with the ZnO:Al/CZTSe thin films showed that process of the absorber layer removal was triggered by a micro-explosive effect induced by high pressure of sublimated material due to a rapid temperature increase at the molybdenum-CZTSe interface.

  5. Development of CIGS2 Thin Films on Ultralightweight Flexible Large Area Foil Sunstrates

    NASA Technical Reports Server (NTRS)

    Dhere, Neelkanth G.; Gade, Vivek S.; Kadam, Ankur A.; Jahagirdar, Anant H.; Kulkarni, Sachin S.; Bet, Sachin M.

    2005-01-01

    The development of thin film solar cells is aimed at reducing the costs for photovoltaic systems. Use of thin film technology and thin foil substrate such as 5-mil thick stainless steel foil or 1-mil thick Ti would result in considerable costs savings. Another important aspect is manufacturing cost. Current single crystal technology for space power can cost more than $ 300 per watt at the array level and weigh more than 1 kg/sq m equivalent to specific power of approx. 65 W/kg. Thin film material such as CuIn1-xGaxS2 (CIGS2), CuIn(1-x)Ga(x)Se(2-y)S(y) (CIGSS) or amorphous hydrogenated silicon (a-Si:H) may be able to reduce both the cost and mass per unit area by an order of magnitude. Manufacturing costs for solar arrays are an important consideration for total spacecraft budget. For a medium sized 5kW satellite for example, the array manufacturing cost alone may exceed $ 2 million. Moving to thin film technology could reduce this expense to less than $ 500K. Earlier publications have demonstrated the potential of achieving higher efficiencies from CIGSS thin film solar cells on 5-mil thick stainless steel foil as well as initial stages of facility augmentation for depositing thin film solar cells on larger (6 in x 4 in) substrates. This paper presents the developmental study of achieving stress free Mo coating; uniform coatings of Mo back contact and metallic precursors. The paper also presents the development of sol gel process, refurbishment of selenization/sulfurization furnace, chemical bath deposition (CBD) for n-type CdS and scrubber for detoxification of H2S and H2Se gases.

  6. Study on the Humidity Susceptibility of Thin-Film CIGS Absorber

    SciTech Connect

    Pern, F. J.; Egaas, B.; To, B.; Jiang, C. S.; Li, J. V.; Glynn, S.; DeHart, C.

    2010-01-01

    The report summarizes the research on the susceptibility of a thermally co-evaporated CuInGaSe2 (CIGS) thin-film absorber to humidity and its consequence on composition, morphology, electrical and electronic properties, and device efficiency.

  7. Laminated thin film solar module

    SciTech Connect

    Berman, E.; Eisner, K.P.

    1986-11-25

    This patent describes a solar module comprising: a first untempered glass sheet having a first side forming a light receiving face of a solar module and a second side, a thin film photovoltaic device fabricated on the second side of the first glass sheet, a second tempered glass sheet spaced from the second side of the first sheet and forming the primary structural member of the solar module; and a pottant layer filling substantially all space between the first and second glass sheets and bonding the sheets together. This patent describes a solar module according to claim 1 further including a second thin film photovoltaic device fabricated on a surface of the second tempered glass sheet.

  8. NREL Produces Highly Efficient, Wide-Bandgap, Thin-Film Solar Cells (Fact Sheet)

    SciTech Connect

    Not Available

    2012-09-01

    Researchers at the National Renewable Energy Laboratory (NREL) are finding new ways to manufacture thin-film solar cells made from copper, indium, gallium, and selenium - called CIGS cells - that are different than conventional CIGS solar cells. Their use of high-temperature glass, designed by SCHOTT AG, allows higher fabrication temperatures, opening the door to new CIGS solar cells employing light-absorbing materials with wide 'bandgaps.'

  9. XPS Investigation of Surface Secondary Phase Segregation in CIGS Thin Film

    SciTech Connect

    Al-Thani, H. A.; Abdullah, M. M.; Hasoon, F. S.

    2011-01-01

    Cu(In, Ga)Se{sub 2} (CIGS) thin films were deposited on Molybdenum (Mo) coated soda lime glass (SLG/Mo) substrates, using physical vapor deposition (PVD) 3-stage process. The Mo thin films were sputtered on SLG substrates using DC planar magnetron sputtering at a working gas (Ar) pressure that varies from 0.8 mT to 12 mT with a sputtering power density of 1.2 W/cm{sub 2}. The sputtering pressure of Mo thin films was varied in order to induce variations in the sputtered films morphology and porosity; as well as to subsequently induce variations in the Na out-diffusion from SLG substrate. The surface chemistry of CIGS thin films was investigated by X-Ray Photoelectron Spectroscopy (XPS). The XPS surface surveys (top 30A) and depth profiling survey (top 100A) for the elements, their chemical states, and their relative concentration were analyzed for CIGS thin films. The XPS surface analysis and composition of CIGS thin films were correlated to the bulk composition and Na out-diffusion in the CIGS films from SLG substrates.

  10. Modeling of polycrystalline thin film solar cells

    NASA Astrophysics Data System (ADS)

    Fahrenbruch, Alan L.

    1999-03-01

    This paper describes modeling polycrystalline thin-film solar cells using the program AMPS-1D1 to visualize the relationships between the many variables involved. These simulations are steps toward two dimensional modeling the effects of grain boundaries in polycrystalline cells. Although this paper describes results for the CdS/CdTe cell, the ideas presented here are applicable to copper-indium-gallium selenide (CIGS) cells as well as other types of cells. Results of these one-dimensional simulations are presented: (a) the duplication of experimentally observed cell parameters, (b) the effects of back-contact potential barrier height and its relation to stressing the cell, (c) the effects of the depletion layer width in the CdTe layer on cell parameters, and (d) the effects of CdS layer thickness on the cell parameters. Experience using the software is also described.

  11. Thin film solar energy collector

    DOEpatents

    Aykan, Kamran; Farrauto, Robert J.; Jefferson, Clinton F.; Lanam, Richard D.

    1983-11-22

    A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

  12. [Study on the modified surface layers of the CIGS thin films by Raman spectra].

    PubMed

    Liu, Wei; Sun, Yun; Li, Feng-Yan; He, Qing; Li, Chang-Jian; Tian, Jian-Guo

    2007-04-01

    In the present paper, the properties of Cu(In(1-x) Ga(x)) Se2 (CIGS) thin film absorber materials for the solar cells obtained by selenization of the precursors with In-rich or CuGa-rich surface layers were studied by XRD, SEM and Raman spectra. The photovoltaic devices based on the absorbers were measured and analyzed by illuminated J-V curve subsequently. The performance of the device constructed by the absorbers obtained by selenization of the precursors with CuGa-rich surface layer was improved greatly compared to that with In-rich surface layer. Through Raman spectra measurement, it was found that the Raman peak of the A1 mode was shifted for the CuGa-rich one, which is verified that the band gap of the surface layers was elevated. Moreover the value of increased Ga contents within the surface region of films were calculated by the relation between the Raman shifts and the Ga contents. As a result, the devices based on the thin films with the elevated surface energy band by selenizing the precursors with the CuGa-rich surface layer improved further the V(oc) and FF by about 74 mV and 8% respectively compared to that of corresponding to the one with In-rich surface layers, so that the conversion efficiency of the photovoltaic devices based on these thin films with CuGa-rich surface layer was improved by up to 9.4%. Meanwhile Raman scattering spectroscopy has proven to be a very powerful and useful technique for the surface analysis of such thin film solar cell semiconducuor materials.

  13. Investigation of crystallization behavior of CIG-Se bi-layer thin films.

    PubMed

    Park, Mi Sun; Sung, Shi-Joon; Kim, Dae-Hwan; Kang, Jin-Kyu

    2012-04-01

    Copper indium gallium diselenide (CIGSe) thin film was fabricated via a thermal treatment of GIG-Se bi-layer thin films. A CIG layer was prepared first, by a chemical solution deposition (CSD) process. The Se layer was deposited separately on the CIG layer by evaporation. The GIG-Se bi-layer then underwent a thermal treatment to cause a reaction between the two layers. In order to investigate the mechanism of CIG-Se bi-layer crystallization, the thermal treatment temperature was varied. The properties of the prepared CIGSe2 thin films were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometry (EDS), and UV-visible spectrophotometry.

  14. Comparative alternative materials assessment to screen toxicity hazards in the life cycle of CIGS thin film photovoltaics.

    PubMed

    Eisenberg, Daniel A; Yu, Mengjing; Lam, Carl W; Ogunseitan, Oladele A; Schoenung, Julie M

    2013-09-15

    Copper-indium-gallium-selenium-sulfide (CIGS) thin film photovoltaics are increasingly penetrating the market supply for consumer solar panels. Although CIGS is attractive for producing less greenhouse gas emissions than fossil-fuel based energy sources, CIGS manufacturing processes and solar cell devices use hazardous materials that should be carefully considered in evaluating and comparing net environmental benefits of energy products. Through this research, we present a case study on the toxicity hazards associated with alternative materials selection for CIGS manufacturing. We applied two numeric models, The Green Screen for Safer Chemicals and the Toxic Potential Indicator. To improve the sensitivity of the model outputs, we developed a novel, life cycle thinking based hazard assessment method that facilitates the projection of hazards throughout material life cycles. Our results show that the least hazardous CIGS solar cell device and manufacturing protocol consist of a titanium substrate, molybdenum metal back electrode, CuInS₂ p-type absorber deposited by spray pyrolysis, ZnS buffer deposited by spray ion layer gas reduction, ZnO:Ga transparent conducting oxide (TCO) deposited by sputtering, and the encapsulant polydimethylsiloxane.

  15. Modeling and Simulation of a Dual-Junction CIGS Solar Cell Using Silvaco ATLAS

    DTIC Science & Technology

    2012-12-01

    Indium Gallium Selenide (CIGS) photovoltaic cell is investigated in this thesis. Research into implementing a dual-junction solar cell ...is the use of thin-film solar cells (TFSC) such as the Copper Indium Gallium Selenide, Cu(In,Ga)Se2, (CIGS). Despite their lower cost of production...Silvaco ATLASTM model of a single CIGS cell was created by utilizing actual solar cell parameters (such as layer thicknesses, gallium ratio,

  16. Solution-deposited CIGS thin films for ultra-low-cost photovoltaics

    NASA Astrophysics Data System (ADS)

    Eldada, Louay A.; Hersh, Peter; Stanbery, Billy J.

    2010-09-01

    We describe the production of photovoltaic modules with high-quality large-grain copper indium gallium selenide (CIGS) thin films obtained with the unique combination of low-cost ink-based precursors and a reactive transfer printing method. The proprietary metal-organic inks contain a variety of soluble Cu-, In- and Ga- multinary selenide materials; they are called metal-organic decomposition (MOD) precursors, as they are designed to decompose into the desired precursors. Reactive transfer is a two-stage process that produces CIGS through the chemical reaction between two separate precursor films, one deposited on the substrate and the other on a printing plate in the first stage. In the second stage, these precursors are rapidly reacted together under pressure in the presence of heat. The use of two independent thin films provides the benefits of independent composition and flexible deposition technique optimization, and eliminates pre-reaction prior to the synthesis of CIGS. In a few minutes, the process produces high quality CIGS films, with large grains on the order of several microns, and preferred crystallographic orientation, as confirmed by compositional and structural analysis by XRF, SIMS, SEM and XRD. Cell efficiencies of 14% and module efficiencies of 12% were achieved using this method. The atmospheric deposition processes include slot die extrusion coating, ultrasonic atomization spraying, pneumatic atomization spraying, inkjet printing, direct writing, and screen printing, and provide low capital equipment cost, low thermal budget, and high throughput.

  17. Fabrication of CIGS thin films by using spray pyrolysis and post-selenization

    NASA Astrophysics Data System (ADS)

    Kim, Seong Yeon; Kim, JunHo

    2012-06-01

    We fabricated Cu(In1- x Ga x )Se2 ( x: 0 ˜ 0.4) thin films by using ultrasonic spray pyrolysis and post-selenization. First, we made Cu(In1- x Ga x )S2 ( x: 0 ˜ 0.4) films by ultrasonic spray pyrolysis under an air environment. Then, we converted as-sprayed Cu(In1- x Ga x )S2 (CIGS) films to Cu-(In1- x Ga x )Se2 (CIGSe) films through post-selenization. For all Ga fractions, the sprayed CIGS films were well recrystallized into poly-crystalline CIGSe films with a dominant (112) texture, which was confirmed by X-ray diffraction, Raman spectroscopy and energy dispersive X-ray analyses. This result indicates that CIGSe films with any amount of Ga substitution can be made by converting sprayed CIGS to CIGSe with post-selenization.

  18. High-Efficiency Polycrystalline Thin Film Tandem Solar Cells.

    PubMed

    Kranz, Lukas; Abate, Antonio; Feurer, Thomas; Fu, Fan; Avancini, Enrico; Löckinger, Johannes; Reinhard, Patrick; Zakeeruddin, Shaik M; Grätzel, Michael; Buecheler, Stephan; Tiwari, Ayodhya N

    2015-07-16

    A promising way to enhance the efficiency of CIGS solar cells is by combining them with perovskite solar cells in tandem devices. However, so far, such tandem devices had limited efficiency due to challenges in developing NIR-transparent perovskite top cells, which allow photons with energy below the perovskite band gap to be transmitted to the bottom cell. Here, a process for the fabrication of NIR-transparent perovskite solar cells is presented, which enables power conversion efficiencies up to 12.1% combined with an average sub-band gap transmission of 71% for photons with wavelength between 800 and 1000 nm. The combination of a NIR-transparent perovskite top cell with a CIGS bottom cell enabled a tandem device with 19.5% efficiency, which is the highest reported efficiency for a polycrystalline thin film tandem solar cell. Future developments of perovskite/CIGS tandem devices are discussed and prospects for devices with efficiency toward and above 27% are given.

  19. Structuring of thin film solar cells

    NASA Astrophysics Data System (ADS)

    Eberhardt, Gabriele; Banse, Henrik; Wagner, Uwe; Peschel, Thomas

    2010-02-01

    Laser structuring of different types of thin film layers is a state of the art process in the photovoltaic industry. TCO layers and molybdenum are structured with e.g. 1064 nm lasers. Amorphous silicon, microcrystalline silicon or cadmium telluride are ablated with 515/532 nm lasers. Typical pulse durations of the lasers in use for these material ablation processes are in the nanosecond range. Up to now the common process for CIS/CIGS cells is needle structuring. Hard metal needles scribe lines with a width of 30 to 60 μm into the semiconductor material. A laser technology would have some advantages compared to mechanical scribing. The precision of the lines would be higher (no chipping effects), the laser has no wear out. The dead area (distance from P1 structuring line to P3 structuring line) can be significantly smaller with the laser technology. So we investigate the structuring of CIS/CIGS materials with ultra short pulse lasers of different wavelengths. The ablation rates and the structuring speeds versus the repetition rates have been established. For the different layer thicknesses and line widths we determined the necessary energy densities. After all tests we can calculate the possible reduction of the dead area on the thin film module. The new technology will result in an increase in the efficiency per module of up to 4 %.

  20. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  1. Plasmonics in Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

    2009-10-01

    Thin film solar cells made of amorphous or microcrystalline silicon provide renewable energy at the benefits of low material consumption. As a drawback, these materials don't offer the high carrier mobilities of their crystalline counterpart. Due to low carrier mobilities, increased process times and material consumption, thick absorbing layers have to be avoided. For maintaining the absorption of the impinging light as high as possible, such thin film devices ask for photon management. Here we show how metallic nanoparticles that sustain the excitation of localized plasmon polaritons placed atop of the solar cell or in between two absorbing layers can increase the efficiency of solar cells. Numerical results for 1D as well as 2D periodic arrangements of nanoparticles will be shown.

  2. Effect of substrate temperature and post-annealing on the properties of CIGS thin films deposited using e-beam evaporation

    NASA Astrophysics Data System (ADS)

    Chen, Jieyi; Shen, Honglie; Zhai, Zihao; Li, Jinze; Wang, Wei; Shang, Huirong; Li, Yufang

    2016-12-01

    Cu(InGa)Se2 (CIGS) thin films were prepared using e-beam evaporation on a soda-lime glass substrate. The effect of substrate temperature and the difference between substrate temperature and post-annealing on the properties of the CIGS thin films and solar cells were studied. X-ray diffraction (XRD) and Raman spectroscopy, energy-dispersive spectroscopy, scanning electron microscopy, UV-Vis-NIR and the Hall effect were used to characterize the structural properties, composition, morphology, optical properties and electrical properties of the as-prepared CIGS thin films, respectively. The results demonstrated that the photoelectric properties of CIGS thin films prepared at a substrate temperature of 300 °C were optimal, with an efficiency of 7.1%. As the substrate temperature increased to over 300 °C, element gallium tended to evaporate from the substrate, which resulted in the variation of the Cu/(In  +  Ga) and Ga/(In  +  Ga) ratios of the films. The post-annealing process with in situ annealing temperatures of 300 °C and 400 °C was also studied. The results indicated that the post-annealing process, unlike the process of direct deposition at certain substrate temperatures, was able to avoid the element loss. At 300 °C in situ post-annealing temperature, there formed a ‘polygon grains’ Cu2-x Se phase, which disappeared when the in situ post-annealing temperature rose to 400 °C. The XRD patterns revealed that the post-annealing process made the element diffusion in films more uniform. The post-treated sample with an in situ post-annealing temperature at 400 °C, as a result, showed the highest efficiency of 9.0%, accompanied by the highest open-circuit voltage, short circuit current and fill factor.

  3. Fabrication of solution processed 3D nanostructured CuInGaS₂ thin film solar cells.

    PubMed

    Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

    2014-03-28

    In this study we demonstrate the fabrication of CuInGaS₂ (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ∼1.3 μm. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ∼6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions.

  4. Effects of potassium doping on solution processed kesterite Cu2ZnSnS4 thin film solar cells

    NASA Astrophysics Data System (ADS)

    Tong, Zhengfu; Yan, Chang; Su, Zhenghua; Zeng, Fangqin; Yang, Jia; Li, Yi; Jiang, Liangxing; Lai, Yanqing; Liu, Fangyang

    2014-12-01

    Alkaline metals doping is one of the approaches for achieving high efficiency Cu(In,Ga)Se2 (CIGS) solar cell. Recently, potassium doping helps to break the record efficiency of CIGS solar cell doped with sodium. In this paper, we have investigated how incorporation of potassium can influence the properties of Cu2ZnSnS4 (CZTS) thin film and the performance of resulting solar cell. Our results showed that K doping can enhance the (112) preferred orientation, increase the grain size and reduce the second phase ZnS of the CZTS thin films. After K doping, despite of some drop of Voc for CZTS thin film solar cells, the Rs is decreased and the Jsc is improved markedly, and the solar cell efficiency is boosted.

  5. Thin film CIGS photovoltaic modules: monolithic integration and advanced packaging for high performance, high reliability and low cost

    NASA Astrophysics Data System (ADS)

    Eldada, Louay

    2011-01-01

    In recent years, thin-film photovoltaic companies started realizing their low manufacturing cost potential, and have been grabbing an increasingly larger market share. Copper Indium Gallium Selenide (CIGS) is the most promising thin-film PV material, having demonstrated the highest energy conversion efficiency in both cells and modules. However, most CIGS manufacturers still face the challenge of delivering a reliable and rapid manufacturing process that can scale effectively and deliver on the promise of this material system. HelioVolt has developed a reactive transfer process for CIGS absorber formation that has the benefits of good compositional control, and a fast high-quality CIGS reaction. The reactive transfer process is a two stage CIGS fabrication method. Precursor films are deposited onto substrates and reusable cover plates in the first stage, while in the second stage the CIGS layer is formed by rapid heating with Se confinement. HelioVolt also developed best-in-class packaging technologies that provide unparalleled environmental stability. High quality CIGS films with large grains were fabricated on the production line, and high-performance highreliability monolithic modules with a form factor of 120 cm × 60 cm are being produced at high yield and low cost. With conversion efficiency levels around 14% for cells and 12% for modules, HelioVolt is commercializing the process on its first production line with 20 MW capacity, and is planning its next GW-scale factory.

  6. Antimony selenide thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Zeng, Kai; Xue, Ding-Jiang; Tang, Jiang

    2016-06-01

    Due to their promising applications in low-cost, flexible and high-efficiency photovoltaics, there has been a booming exploration of thin-film solar cells using new absorber materials such as Sb2Se3, SnS, FeS2, CuSbS2 and CuSbSe2. Among them, Sb2Se3-based solar cells are a viable prospect because of their suitable band gap, high absorption coefficient, excellent electronic properties, non-toxicity, low cost, earth-abundant constituents, and intrinsically benign grain boundaries, if suitably oriented. This review surveys the recent development of Sb2Se3-based solar cells with special emphasis on the material and optoelectronic properties of Sb2Se3, the solution-based and vacuum-based fabrication process and the recent progress of Sb2Se3-sensitized and Sb2Se3 thin-film solar cells. A brief overview further addresses some of the future challenges to achieve low-cost, environmentally-friendly and high-efficiency Sb2Se3 solar cells.

  7. Monolithic DSSC/CIGS tandem solar cell fabricated by a solution process.

    PubMed

    Moon, Sung Hwan; Park, Se Jin; Kim, Sang Hoon; Lee, Min Woo; Han, Jisu; Kim, Jin Young; Kim, Honggon; Hwang, Yun Jeong; Lee, Doh-Kwon; Min, Byoung Koun

    2015-03-11

    Tandem architecture between organic (dye-sensitized solar cell, DSSC) and inorganic (CuInGaSe2 thin film solar cell, CIGS) single-junction solar cells was constructed particularly based on a solution process. Arc-plasma deposition was employed for the Pt interfacial layer to minimize the damage to the layers of the CIGS bottom cell. Solar cell efficiency of 13% was achieved, which is significant progress from individual single-junction solar cells (e.g., 7.25 and 6.2% for DSSC and CIGS, respectively).

  8. Monolithic DSSC/CIGS tandem solar cell fabricated by a solution process

    PubMed Central

    Moon, Sung Hwan; Park, Se Jin; Kim, Sang Hoon; Lee, Min Woo; Han, Jisu; Kim, Jin Young; Kim, Honggon; Hwang, Yun Jeong; Lee, Doh-Kwon; Min, Byoung Koun

    2015-01-01

    Tandem architecture between organic (dye-sensitized solar cell, DSSC) and inorganic (CuInGaSe2 thin film solar cell, CIGS) single-junction solar cells was constructed particularly based on a solution process. Arc-plasma deposition was employed for the Pt interfacial layer to minimize the damage to the layers of the CIGS bottom cell. Solar cell efficiency of 13% was achieved, which is significant progress from individual single-junction solar cells (e.g., 7.25 and 6.2% for DSSC and CIGS, respectively). PMID:25759191

  9. Nanocrystalline silicon based thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ray, Swati

    2012-06-01

    Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

  10. Photovoltaic manufacturing cost and throughput improvements for thin-film CIGS-based modules: Phase 1 technical report, July 1998--July 1999

    SciTech Connect

    Wiedeman, S.; Wendt, R.G.

    2000-03-01

    The primary objectives of the Global Solar Energy (GSE) Photovoltaic Manufacturing Technology (PVMaT) subcontract are directed toward reducing cost and expanding the production rate of thin-film CuInGaSe{sub 2} (CIGS)-based PV modules on flexible substrates. Improvements will be implemented in monolithic integration, CIGS deposition, contact deposition, and in-situ CIGS control and monitoring. In Phase 1, GSE has successfully attacked many of the highest risk aspects of each task. All-laser, selective scribing processes for CIGS have been developed, and many end-of-contract goals for scribing speed have been exceeded in the first year. High-speed ink-jet deposition of insulating material in the scribes now appears to be a viable technique, again exceeding some end-of-contract goals in the first year. Absorber deposition of CIGS was reduced corresponding to throughput speeds of up to 24-in/min, also exceeding an end-of-contract goal. Alternate back-contact materials have been identified that show potential as candidates for replacement of higher-cost molybdenum, and a novel, real-time monitoring technique (parallel-detector spectroscopic ellipsometry) has shown remarkable sensitivity to relevant properties of the CIGS absorber layer for use as a diagnostic tool. Currently, one of the bilayers has been baselined by GSE for flexible CIGS on polymeric substrates. Resultant back-contacts meet sheet-resistance goals and exhibit much less intrinsic stress than Mo. CIGS has been deposited, and resultant devices are comparable in performance to pure Mo back-contacts. Debris in the chamber has been substantially reduced, allowing longer roll-length between system cleaning.

  11. Research on polycrystalline thin-film CuGaInSe2 solar cells

    NASA Astrophysics Data System (ADS)

    Stanbery, B. J.; Chen, W. S.; Devaney, W. E.; Stewart, J. W.

    1992-11-01

    This report describes research to fabricate high-efficiency CdZnS/CuInGaSe2 (CIGS) thin-film solar cells, and to develop improved transparent conductor window layers such as ZnO. A specific technical milestone was the demonstration of an air mass (AM) 1.5 global, 13 percent efficient, 1-sq cm total-area CIGS thin-film solar cell. Our activities focused on three areas. First, a CIGS deposition system was modified to double its substrate capacity, thus increasing throughput, which is critical to speeding the process development by providing multiple substrates from the same CIGS run. Second, new tooling was developed to enable an investigation of a modified aqueous CdZnS process. The goal was to improve the yield of this critical step in the device fabrication process. Third, our ZnO sputtering system was upgraded to improve its reliability, and the sputtering parameters were further optimized to improve its properties as a transparent conducting oxide. The characterization of the new CIGS deposition system substrate fixturing was completed, and we produced good thermal uniformity and adequately high temperatures for device-quality CIGS deposition. Both the CIGS and ZnO deposition processes were refined to yield a ZnO / Cd(0.82)Zn(0.18)S / CuIn(0.80)Ga(0.20)Se2 cell that was verified at NREL under standard testing conditions at 13.1 percent efficiency with V(sub oc) = 0.581 V, J(sub sc) = 34.8 mA/sq cm, FF = 0.728, and a cell area of 0.979 sq cm.

  12. Nanostructured refractory thin films for solar applications

    NASA Astrophysics Data System (ADS)

    Ollier, E.; Dunoyer, N.; Dellea, O.; Szambolics, H.

    2014-08-01

    Selective solar absorbers are key elements of all solar thermal systems. Solar thermal panels and Concentrated Solar Power (CSP) systems aim respectively at producing heat and electricity. In both cases, a surface receives the solar radiation and is designed to have the highest optical absorption (lowest optical reflectivity) of the solar radiation in the visible wavelength range where the solar intensity is the highest. It also has a low emissivity in the infrared (IR) range in order to avoid radiative thermal losses. Current solutions in the state of the art usually consist in deposited interferential thin films or in cermets [1]. Structured surfaces have been proposed and have been simulated because they are supposed to be more efficient when the solar radiation is not normal to the receiving surface and because they could potentially be fabricated with refractory materials able to sustain high operating temperatures. This work presents a new method to fabricate micro/nanostructured surfaces on molybdenum (refractory metal with a melting temperature of 2623°C). This method now allows obtaining a refractory selective surface with an excellent optical selectivity and a very high absorption in the visible range. This high absorption performance was obtained by achieving a double structuration at micro and nano scales thanks to an innovative process flow.

  13. Selective Ablation of Thin Films with Picosecond-Pulsed Lasers for Solar Cells

    NASA Astrophysics Data System (ADS)

    Račiukaitis, G.; Gečys, P.; Gedvilas, M.; Regelskis, K.; Voisiat, B.

    2010-10-01

    Functional thin-films are of high importance in modern electronics for flat panel displays, photovoltaics, flexible and organic electronics. Versatile technologies are required for patterning thin-film materials on rigid and flexible substrates. The large-area applications of thin films such as photovoltaics need high speed and simple to use techniques. Ultra-short laser processing with its flexibility is one of the ways to achieve high quality material etching but optimization of the processes is required to meet specific needs of the applications. Lasers with picosecond pulse duration were applied in selective ablation of conducting, semi-conducting and isolating films in the complex multilayered thin-film solar cells based on amorphous Si and CuInxGa(1-x)Se2 (CIGS) deposited on glass and polymer substrates. Modeling of energy transition between the layers and temperature evolution was performed to understand the processes. Selection of the right laser wavelength was important to keep the energy coupling in a well defined volume at the interlayer interface. Ultra-short pulses ensured high energy input rate into absorbing material permitting peeling of the layers with no influence on the remaining material. Use of high repetition rate lasers with picosecond pulse duration offers new possibilities for high quality and efficiency patterning of advanced materials for thin-film electronics.

  14. Efficiency limiting factors in Cu(In,Ga)Se2 thin film solar cells prepared by Se-free rapid thermal annealing of sputter-deposited Cu-In-Ga-Se precursors

    NASA Astrophysics Data System (ADS)

    Young Park, Ha; Gwon Moon, Dong; Ho Yun, Jae; Ahn, Seoung Kyu; Yoon, Kyung Hoon; Ahn, SeJin

    2013-12-01

    We report an efficiency limiting factor of CuInGaSe2 (CIGS) thin film solar cells fabricated by rapid thermal annealing (RTA) of sputter-deposited Cu-In-Ga-Se films without an additional supply of Se vapor. The CIGS thin films show a single-phase chalcopyrite structure without Ga segregation, and there is no apparent Se deficiency in overall composition measured by routine compositional analysis. However, detailed investigation on properties of the CIGS films and devices reveals that the formation of Se vacancies on the CIGS film surface during Se-free RTA is a main limiting factor of the device efficiency.

  15. Cosine light-trapping nanostructures for thin film solar cells.

    PubMed

    Guo, Xiaowei; Zhou, Yong; Liu, Bang; Li, Yi

    2015-08-15

    In this Letter, we present a cosine light-trapping texture for thin-film silicon solar cells. The surface texture was numerically demonstrated to exhibit comparable light-trapping performance to the inverted pyramid one, which is classic high-efficiency light-trapping structure. The cosine texture can be directly formed by interference lithography, while the inverted pyramid needs more complicated processing. The proposed structure has the potential to play a key role in thin-film solar cells.

  16. Thin-Film Solar Cells on Metal Foil Substrates for Space Power

    NASA Technical Reports Server (NTRS)

    Raffaelle, Ryne P.; Hepp, Aloysius F.; Hoffman, David J.; Dhere, N.; Tuttle, J. R.; Jin, Michael H.

    2004-01-01

    Photovoltaic arrays have played a key role in power generation in space. The current technology will continue to evolve but is limited in the important mass specific power metric (MSP or power/weight ratio) because it is based on bulk crystal technology. The objective of this research is to continue development of an innovative photovoltaic technology for satellite power sources that could provide up to an order of magnitude saving in both weight and cost, and is inherently radiation-tolerant through use of thin film technology and thin foil substrates such as 5-mil thick stainless steel foil or 1-mil thick Ti. Current single crystal technology for space power can cost more than $300 per watt at the array level and weigh more than 1 kg/sq m equivalent to specific power of approx. 65 W/kg. Thin film material such as CuIn(1-x),Ga(x)S2, (CIGS2), CuIn(1-x), G(x)Se(2-y),S(y), (CIGSS) or amorphous hydrogenated silicon (a-Si:H) may be able to reduce both the cost and mass per unit area by an order of magnitude. Manufacturing costs for solar arrays are an important consideration for total spacecraft budget. For a medium sized 5kW satellite, for example, the array manufacturing cost alone may exceed $2 million. Moving to thin film technology could reduce this expense to less than $500 K. Previous work at FSEC demonstrated the potential of achieving higher efficiencies from CIGSS thin film solar cells on 5-mil thick stainless steel foil as well as initial stages of facility augmentation for depositing thin film solar cells on larger (6"x 4") substrates. This paper presents further progress in processing on metal foil substrates. Also, previous work at DayStar demonstrated the feasibility of flexible-thin-film copper-indium-gallium-diselenide (CIGS) solar cells with a power-to-weight ratio in excess of 1000 W/kg. We will comment on progress on the critical issue of scale-up of the solar cell absorber deposition process. Several important technical issues need to be resolved

  17. Novel wide band gap materials for highly efficient thin film tandem solar cells. Final report

    SciTech Connect

    Brian E. Hardin; Connor, Stephen T.; Peters, Craig H.

    2012-06-11

    films using a mixture of solution and physical vapor deposition processing, but these films lacked the p-type doping levels that are required to make decent solar cells. Over the course of the project PLANT PV was able to fabricate efficient CIGS solar cells (8.7%) but could not achieve equivalent performance using AIGS. During the nine-month grant PLANT PV set up a variety of thin film characterization tools (e.g. drive-level capacitance profiling) at the Molecular Foundry, a Department of Energy User Facility, that are now available to both industrial and academic researchers via the grant process. PLANT PV was also able to develop the back end processing of thin film solar cells at Lawrence Berkeley National Labs to achieve 8.7% efficient CIGS solar cells. This processing development will be applied to other types of thin film PV cells at the Lawrence Berkeley National Labs. While PLANT PV was able to study AIGS film growth and optoelectronic properties we concluded that AIGS produced using these methods would have a limited efficiency and would not be commercially feasible. PLANT PV did not apply for the Phase II of this grant.

  18. PHOTOVOLTAIC AND THERMOELECTRIC SOLAR ENERGY CONVERSION USING THIN FILMS,

    DTIC Science & Technology

    Solar energy conversion by the use of thin films in photovoltaic and thermoelectric devices is discussed. Experimental work is presented on the fabrication of a thin film cadmium sulfide cell which utilizes the photovoltaic effect. A theoretical investigation is made of the temperature differences obtainable in space by using thin, light-weight plastic sheets, and the use of such plastics for thermoelectric generators is discussed. Temperature differences of several hundred centrigrade degrees can be obtained. (Author)

  19. Recent Progress in CuInS2 Thin-Film Solar Cell Research at NASA Glenn

    NASA Technical Reports Server (NTRS)

    Jin, M. H.-C.; Banger, K. K.; Kelly, C. V.; Scofield, J. H.; McNatt, J. S.; Dickman, J. E.; Hepp, A. F.

    2005-01-01

    The National Aeronautics and Space Administration (NASA) is interested in developing low-cost highly efficient solar cells on light-weight flexible substrates, which will ultimately lower the mass-specific power (W/kg) of the cell allowing extra payload for missions in space as well as cost reduction. In addition, thin film cells are anticipated to have greater resistance to radiation damage in space, prolonging their lifetime. The flexibility of the substrate has the added benefit of enabling roll-to-roll processing. The first major thin film solar cell was the "CdS solar cell" - a heterojunction between p-type CuxS and n-type CdS. The research on CdS cells started in the late 1950s and the efficiency in the laboratory was up to about 10 % in the 1980s. Today, three different thin film materials are leading the field. They include amorphous Si, CdTe, and Cu(In,Ga)Se2 (CIGS). The best thin film solar cell efficiency of 19.2 % was recently set by CIGS on glass. Typical module efficiencies, however, remain below 15 %.

  20. Thin-Film Solar Array Earth Orbit Mission Applicability Assessment

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Kerslake, Thomas W.; Hepp, Aloysius F.; Raffaelle, Ryne P.

    2002-01-01

    This is a preliminary assessment of the applicability and spacecraft-level impact of using very lightweight thin-film solar arrays with relatively large deployed areas for representative Earth orbiting missions. The most and least attractive features of thin-film solar arrays are briefly discussed. A simple calculation is then presented illustrating that from a solar array alone mass perspective, larger arrays with less efficient but lighter thin-film solar cells can weigh less than smaller arrays with more efficient but heavier crystalline cells. However, a proper spacecraft-level systems assessment must take into account the additional mass associated with solar array deployed area: the propellant needed to desaturate the momentum accumulated from area-related disturbance torques and to perform aerodynamic drag makeup reboost. The results for such an assessment are presented for a representative low Earth orbit (LEO) mission, as a function of altitude and mission life, and a geostationary Earth orbit (GEO) mission. Discussion of the results includes a list of specific mission types most likely to benefit from using thin-film arrays. NASA Glenn's low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is also briefly discussed to provide a perspective on one approach to achieving this enabling technology. The paper concludes with a list of issues to be addressed prior to use of thin-film solar arrays in space and the observation that with their unique characteristics, very lightweight arrays using efficient, thin-film cells on flexible substrates may become the best array option for a subset of Earth orbiting missions.

  1. Ternary Precursors for Depositing I-III-VI2 Thin Films for Solar Cells via Spray CVD

    NASA Technical Reports Server (NTRS)

    Banger, K. K.; Hollingsworth, J. A.; Jin, M. H.-C.; Harris, J. D.; Duraj, S. A.; Smith, M.; Scheiman, D.; Bohannan, E. W.; Switzer, J. A.; Buhro, W. E.

    2002-01-01

    The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors (SSP's) can be used in either a hot or cold-wall spray chemical vapour deposition (CVD) reactor, for depositing CuInS2, CuGaS2, and CuGaInS2 at reduced temperatures (400 to 450 C), which display good electrical and optical properties suitable for photovoltaic (PV) devices. X-ray diffraction studies, energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures.

  2. Thin-film copper indium gallium selenide solar cell based on low-temperature all-printing process.

    PubMed

    Singh, Manjeet; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-09-24

    In the solar cell field, development of simple, low-cost, and low-temperature fabrication processes has become an important trend for energy-saving and environmental issues. Copper indium gallium selenide (CIGS) solar cells have attracted much attention due to the high absorption coefficient, tunable band gap energy, and high efficiency. However, vacuum and high-temperature processing in fabrication of solar cells have limited the applications. There is a strong need to develop simple and scalable methods. In this work, a CIGS solar cell based on all printing steps and low-temperature annealing is developed. CIGS absorber thin film is deposited by using dodecylamine-stabilized CIGS nanoparticle ink followed by printing buffer layer. Silver nanowire (AgNW) ink and sol-gel-derived ZnO precursor solution are used to prepare a highly conductive window layer ZnO/[AgNW/ZnO] electrode with a printing method that achieves 16 Ω/sq sheet resistance and 94% transparency. A CIGS solar cell based on all printing processes exhibits efficiency of 1.6% with open circuit voltage of 0.48 V, short circuit current density of 9.7 mA/cm(2), and fill factor of 0.34 for 200 nm thick CIGS film, fabricated under ambient conditions and annealed at 250 °C.

  3. Thin-Film Photovoltaic Solar Array Parametric Assessment

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.; Kerslake, Thomas W.; Hepp, Aloysius F.; Jacobs, Mark K.; Ponnusamy, Deva

    2000-01-01

    This paper summarizes a study that had the objective to develop a model and parametrically determine the circumstances for which lightweight thin-film photovoltaic solar arrays would be more beneficial, in terms of mass and cost, than arrays using high-efficiency crystalline solar cells. Previous studies considering arrays with near-term thin-film technology for Earth orbiting applications are briefly reviewed. The present study uses a parametric approach that evaluated the performance of lightweight thin-film arrays with cell efficiencies ranging from 5 to 20 percent. The model developed for this study is described in some detail. Similar mass and cost trends for each array option were found across eight missions of various power levels in locations ranging from Venus to Jupiter. The results for one specific mission, a main belt asteroid tour, indicate that only moderate thin-film cell efficiency (approx. 12 percent) is necessary to match the mass of arrays using crystalline cells with much greater efficiency (35 percent multi-junction GaAs based and 20 percent thin-silicon). Regarding cost, a 12 percent efficient thin-film array is projected to cost about half is much as a 4-junction GaAs array. While efficiency improvements beyond 12 percent did not significantly further improve the mass and cost benefits for thin-film arrays, higher efficiency will be needed to mitigate the spacecraft-level impacts associated with large deployed array areas. A low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is briefly described. The paper concludes with the observation that with the characteristics assumed for this study, ultra-lightweight arrays using efficient, thin-film cells on flexible substrates may become a leading alternative for a wide variety of space missions.

  4. Single Source Precursors for Thin Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Hollingsworth, Jennifer A.; Harris, Jerry D.; Cowen, Jonathan; Buhro, William E.; Hepp, Aloysius F.

    2002-01-01

    The development of thin film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. At NASA GRC we have focused on the development of new single source precursors (SSP) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD (chemical vapor deposition) process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV (photovoltaic) devices.

  5. Thin film solar cells: research in an industrial perspective.

    PubMed

    Edoff, Marika

    2012-01-01

    Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se(2) and Cu(2)ZnSn(S,Se)(4) as the sunlight-absorbing layer.

  6. Advanced Thin Film Solar Arrays for Space: The Terrestrial Legacy

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Hepp, Aloysius; Raffaelle, Ryne; Flood, Dennis

    2001-01-01

    As in the case for single crystal solar cells, the first serious thin film solar cells were developed for space applications with the promise of better power to weight ratios and lower cost. Future science, military, and commercial space missions are incredibly diverse. Military and commercial missions encompass both hundreds of kilowatt arrays to tens of watt arrays in various earth orbits. While science missions also have small to very large power needs there are additional unique requirements to provide power for near sun missions and planetary exploration including orbiters, landers, and rovers both to the inner planets and the outer planets with a major emphasis in the near term on Mars. High power missions are particularly attractive for thin film utilization. These missions are generally those involving solar electric propulsion, surface power systems to sustain an outpost or a permanent colony on the surface of the Moon or Mars, space based lasers or radar, or large Earth orbiting power stations which can serve as central utilities for other orbiting spacecraft, or potentially beaming power to the Earth itself. This paper will discuss the current state of the art of thin film solar cells and the synergy with terrestrial thin film photovoltaic evolution. It will also address some of the technology development issues required to make thin film photovoltaics a viable choice for future space power systems.

  7. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-08-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple.

  8. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    PubMed Central

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-01-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple. PMID:27489138

  9. Integrated thin film cadmium sulfide solar cell module

    NASA Technical Reports Server (NTRS)

    Mickelsen, R. A.; Abbott, D. D.

    1971-01-01

    The design, development, fabrication and tests of flexible integrated thin-film cadmium sulfide solar cells and modules are discussed. The development of low cost and high production rate methods for interconnecting cells into large solar arrays is described. Chromium thin films were applied extensively in the deposited cell structures as a means to: (1) achieve high adherence between the cadmium sulfide films and the vacuum-metallized copper substrates, (2) obtain an ohmic contact to the cadmium sulfide films, and (3) improve the adherence of gold films as grids or contact areas.

  10. Annealing of Solar Cells and Other Thin Film Devices

    NASA Technical Reports Server (NTRS)

    Escobar, Hector; Kuhlman, Franz; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

    2001-01-01

    Annealing is a key step in most semiconductor fabrication processes, especially for thin films where annealing enhances performance by healing defects and increasing grain sizes. We have employed a new annealing oven for the annealing of CdTe-based solar cells and have been using this system in an attempt to grow US on top of CdTe by annealing in the presence of H2S gas. Preliminary results of this process on CdTe solar cells and other thin-film devices will be presented.

  11. Micro-structuring of CIGS thin-film coated on Mo back contact by ultrafast laser 'rail-roading' patterning.

    PubMed

    Jeoung, Sae Chae; Lee, Heung-Soon; Yahng, Ji Sang; Lee, Hyun Kyu; Moon, Heh Young; Kim, Kyoun Joon; Lee, Dong Geun; Park, Duck Hoon; Yu, Young Sam; Ji, Suk-Jae

    2011-08-29

    We report selective patterning process, laser 'rail-roading' scribing method, of which operating principle is based on transient force balance between the material properties including cohesion and adhesion forces subjected to underlying substrate and laser-induced shock compression and shear forces. By using dual fs-laser beam lines with an interval larger than laser spot size, we provide a proof of the concept by patterning the photovoltaic modules based on CIGS (Cu(In,Ga)Se2) coated on Mo electrode. With varying the interval between the two laser beam tracks, we can provide intact Mo back contact surface without any residues in a manner of more facile, high-speed and high scribing efficiency. We have interpreted the effect of the ambient gases and grooving width on the scribing performance in terms of the cohesion forces between the grains of CIGS thin films as well as adhesion force between underlying Mo layer and CIGS, which are mainly governed by local laser ablation and peening process followed by laser-induced shock compression, respectively.

  12. Thin film metallic glass as a diffusion barrier for copper indium gallium selenide solar cell on stainless steel substrate: A feasibility study

    NASA Astrophysics Data System (ADS)

    Diyatmika, Wahyu; Xue, Lingjun; Lin, Tai-Nan; Chang, Chia-wen; Chu, Jinn P.

    2016-08-01

    The feasibility of using Zr53.5Cu29.1Al6.5Ni10.9 thin-film metallic glass (TFMG) as a diffusion barrier for copper indium gallium selenide (CIGS) solar cells on stainless steel (SS) is investigated. The detrimental Fe diffusion from SS into CIGS is found to be effectively hindered by the introduction of a 70-nm-thick TFMG barrier; the cell performance is thus improved. Compared with the 2.73% of CIGS on bare SS, a higher efficiency of 5.25% is obtained for the cell with the Zr52Cu32Al9Ni7 TFMG barrier.

  13. A Comprehensive Study of One-Step Selenization Process for Cu(In1-x Ga x )Se2 Thin Film Solar Cells.

    PubMed

    Chen, Shih-Chen; Wang, Sheng-Wen; Kuo, Shou-Yi; Juang, Jenh-Yih; Lee, Po-Tsung; Luo, Chih Wei; Wu, Kaung-Hsiung; Kuo, Hao-Chung

    2017-12-01

    In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn1-x Ga x Se2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H2Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra. The surface morphologies examined by scanning electron microscope (SEM) further suggested that voids and binary phase commonly existing in CIGS films could be successfully eliminated by the present one-step selenization process. The agglomeration phenomenon attributable to the formation of MoSe2 layer was also observed. Due to the significant microstructural improvement, the current-voltage (J-V) characteristics and external quantum efficiency (EQE) of the devices made of the present CIGS films have exhibited the remarkable carrier transportation characteristics and photon utilization at the optimal location, resulting in a high conversion efficiency of 11.28%. Correlations between the defect states and device performance of the one-step selenized CIGS thin film were convincingly delineated by femtosecond pump-probe spectroscopy.

  14. A Comprehensive Study of One-Step Selenization Process for Cu(In1- x Ga x )Se2 Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Chen; Wang, Sheng-Wen; Kuo, Shou-Yi; Juang, Jenh-Yih; Lee, Po-Tsung; Luo, Chih Wei; Wu, Kaung-Hsiung; Kuo, Hao-Chung

    2017-03-01

    In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn1- x Ga x Se2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H2Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra. The surface morphologies examined by scanning electron microscope (SEM) further suggested that voids and binary phase commonly existing in CIGS films could be successfully eliminated by the present one-step selenization process. The agglomeration phenomenon attributable to the formation of MoSe2 layer was also observed. Due to the significant microstructural improvement, the current-voltage ( J- V) characteristics and external quantum efficiency (EQE) of the devices made of the present CIGS films have exhibited the remarkable carrier transportation characteristics and photon utilization at the optimal location, resulting in a high conversion efficiency of 11.28%. Correlations between the defect states and device performance of the one-step selenized CIGS thin film were convincingly delineated by femtosecond pump-probe spectroscopy.

  15. Research on polycrystalline thin-film CuInGaSe2 solar cells

    NASA Astrophysics Data System (ADS)

    Chen, W. S.; Stewart, J. M.; Mickelsen, R. A.; Devaney, W. E.; Stanbery, B. J.

    1993-10-01

    This report describes work to fabricate high-efficiency CdZnS/CuInGaSe2, thin-film solar cells and to develop improved transparent conductor window layers such as ZnO. The specific technical milestone for Phase 1 was to demonstrate an air mass (AM) 1.5 global 13% , 1-cm(exp 2) total-area CuInGaSe2 (CIGS) thin-film solar cell. For Phase 2, the objective was to demonstrate an AM1.5 global 13.5%, 1-cm(exp 2) total-area efficiency. We focused our activities on three areas. First, we modified the CIGS deposition system to double its substrate capacity. Second, we developed new tooling to enable investigation of a modified aqueous CdZnS process in which the goal was to improve the yield of this critical step in the device fabrication process. Third, we upgraded the ZnO sputtering system to improve its reliability and reproducibility. A dual rotatable cathode metallic source was installed, and the sputtering parameters were further optimized to improve ZnO's properties as a transparent conducting oxide (TCO). Combining the refined CdZnS process with CIGS from the newly fixtured deposition system enable us to fabricate and deliver a ZnO/Cd(0.08)Zn(0.20)S/CuIn(0.74)Ga(0.26)Se2 cell on alumina with I-V characteristics, as measured by NREL under standard test conditions, of 13.7% efficiency with V(proportional to) = 0.5458 V, J(sub sc) = 35.48 mA/cm(exp 2), FF = 0.688, and efficiency = 14.6%.

  16. Buried contact multijunction thin film silicon solar cell

    SciTech Connect

    Green, M.

    1995-08-01

    In early 1994, the Center for Photovoltaic Devices and Systems announced the filing of patent applications on an improved silicon thin film photovoltaic module approach. With material costs estimated to be about 20 times lower than those in present silicon solar cell modules along with other production advantages, this technology appears likely to make low cost, high performance solar modules available for the first time. This paper describes steps involved in making a module and module performance.

  17. Membrane transfer of crystalline silicon thin film solar cells

    NASA Astrophysics Data System (ADS)

    Vempati, Venkata Kesari Nandan

    Silicon has been dominating the solar industry for many years and has been touted as the gold standard of the photovoltaic world. The factors for its dominance: government subsidies and ease of processing. Silicon holds close to 90% of the market share in the material being used for solar cell production. Of which 14% belongs to single-crystalline Silicon. Although 24% efficient bulk crystalline solar cells have been reported, the industry has been looking for thin film alternatives to reduce the cost of production. Moreover with the new avenues like flexible consumer electronics opening up, there is a need to introduce the flexibility into the solar cells. Thin film films make up for their inefficiency keeping their mechanical properties intact by incorporating Anti-reflective schemes such as surface texturing, textured back reflectors and low reflective surfaces. This thesis investigates the possibility of using thin film crystalline Silicon for fabricating solar cells and has demonstrated a low cost and energy efficient way for fabricating 2microm thick single crystalline Silicon solar cells with an efficiency of 0.8% and fill factor of 35%.

  18. Scanning Tunneling Microscopy of Multilayer Thin Film Solar Cell Materials^*

    NASA Astrophysics Data System (ADS)

    Mantovani, J. G.; Friedfeld, R.; Raffaelle, R. P.

    1996-03-01

    We have been investigating electrochemically deposited multilayer structures based on the Cu_xIn_2-xSe2 system for use in thin film solar cells. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. We have imaged the artificially imposed superstructure of our nanoscale multilayers using a scanning tunneling microscope. A comparison is made between the theoretically calculated modulation wavelengths and those generated by Fourier analysis of the scanning tunneling microscope images. A discussion of the use of photo-assisted tunneling spectroscopy in a modified STM is presented. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  19. Optical properties of Cd{sub 1-x}Zn{sub x}S thin films for CuInGaSe{sub 2} solar cell application

    SciTech Connect

    Zhou, Zhen; Zhao, Kui; Huang, Fuqiang

    2010-10-15

    The photovoltaic Cd{sub 1-x}Zn{sub x}S thin films, fabricated by chemical bath deposition, were successfully used as n-type buffer layer in CuInGaSe{sub 2} (CIGS) solar cells. Comprehensive optical properties of the Cd{sub 1-x}Zn{sub x}S thin films were measured and modeled by spectroscopic ellipsometry (SE), which is proven to be an excellent and non-destructive technique to determine optical properties of thin films. The optical band gap of Cd{sub 1-x}Zn{sub x}S thin films can be tuned from 2.43 eV to 3.25 eV by controlling the Zn content (x) and deposition conditions. The wider-band-gap Cd{sub 1-x}Zn{sub x}S film was found to be favorable to improve the quantum efficiency in the wavelength range of 450-550 nm, resulting in an increase of short-circuits current for solar cells. From the characterization of quantum efficiency (QE) and current-voltage curve (J-V) of CIGS cells, the Cd{sub 1-x}Zn{sub x}S films (x = 0.32, 0.45) were demonstrated to significantly enhance the photovoltaic performance of CIGS solar cell. The highest efficiency (10.5%) of CIGS solar cell was obtained using a dense and homogenous Cd{sub 0.68}Zn{sub 0.32}S thin film as the buffer layer.

  20. ADVANCED THIN-FILM SOLAR CELLS.

    DTIC Science & Technology

    SEMICONDUCTING FILMS), (* SOLAR CELLS , GALLIUM ARSENIDES, TRANSPORT PROPERTIES, SUBSTRATES, MASS SPECTROSCOPY, CAPACITANCE, PREPARATION, PROCESSING, LABORATORY FURNACES, IMPURITIES, STABILITY, OXIDES.

  1. High efficiency thin-film GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.

    1977-01-01

    Several oxidation techniques are discussed which have been found to increase the open circuit (V sub oc) of metal-GaAs Schottky barrier solar cells, the oxide chemistry, attempts to measure surface state parameters, the evolving characteristics of the solar cell as background contamination (has been decreased, but not eliminated), results of focused Nd/YAG laser beam recrystallization of Ge films evaporated onto tungsten, and studies of AMOS solar cells fabricated on sliced polycrystalline GaAs wafers. Also discussed are projected materials availability and costs for GaAs thin-film solar cells.

  2. Light-Induced Degradation of Thin Film Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Hamelmann, F. U.; Weicht, J. A.; Behrens, G.

    2016-02-01

    Silicon-wafer based solar cells are still domination the market for photovoltaic energy conversion. However, most of the silicon is used only for mechanical stability, while only a small percentage of the material is needed for the light absorption. Thin film silicon technology reduces the material demand to just some hundred nanometer thickness. But even in a tandem stack (amorphous and microcrystalline silicon) the efficiencies are lower, and light-induced degradation is an important issue. The established standard tests for characterisation are not precise enough to predict the performance of thin film silicon solar cells under real conditions, since many factors do have an influence on the degradation. We will show some results of laboratory and outdoor measurements that we are going to use as a base for advanced modelling and simulation methods.

  3. Polymer Substrates For Lightweight, Thin-Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Lewis, Carol R.

    1993-01-01

    Substrates survive high deposition temperatures. High-temperature-resistant polymers candidate materials for use as substrates of lightweight, flexible, radiation-resistant solar photovoltaic cells. According to proposal, thin films of copper indium diselenide or cadmium telluride deposited on substrates to serve as active semiconductor layers of cells, parts of photovoltaic power arrays having exceptionally high power-to-weight ratios. Flexibility of cells exploited to make arrays rolled up for storage.

  4. ADVANCED THIN-FILM SOLAR CELLS.

    DTIC Science & Technology

    SEMICONDUCTING FILMS), (* SOLAR CELLS , MANUFACTURING, GALLIUM ALLOYS, ARSENIC ALLOYS, PLATINUM, OXIDES, TRANSPORT PROPERTIES, MOLYBDENUM, METAL FILMS, COPPER, HYDROGEN, GERMANIUM ALLOYS, TIN ALLOYS, ZINC, CRYSTAL GROWTH.

  5. Photon upconversion for thin film solar cells

    NASA Astrophysics Data System (ADS)

    de Wild, J.

    2012-09-01

    In this research one of the many possible methods to increase the efficiency of solar cells is described. The method investigated is based on adapting the solar light in such a way that the solar cell can convert more light into electricity. The part of the solar spectrum that is adapted is the part that cannot be absorbed by the solar cells, because the photon energy is too low. This conversion of light is done by so called upconversion, which means that lower energy photons are converted into higher energy photons that can be absorbed by the solar cell. The upconverters used in this thesis are those based on lanthanide ions doped in crystalline hosts. Lanthanide ions have very specific absorption and emission lines, which means that by choosing an appropriate ion one can convert any arbitrary wavelength. One of the most important aspects when one wants to apply upconverters onto solar cells is the light intensity necessary for efficient conversion. Because the upconversion process requires two photons to make a new, higher energy photon, the conversion process is non-linearly dependent on the light intensity. This is the main limitation for practical applications. Therefore, next to applying upconverters onto solar cells also more fundamental questions are addressed in this thesis, for instance, the question what determines efficient conversion. At first the upconverter materials in different hosts are characterized and investigated. The host material influences non-radiative decays, the absorption strength, the lifetime and the energy transfer rate between the lanthanide ions. By investigating two upconverter hosts with small differences (α and β-NaYF4 doped with Er3+ and Yb3+), we have tried to investigate the origin of the difference in upconversion efficiency. For this, emission and absorption spectra are measured under the same conditions and concentrations of the lanthanide ions. Also the absorption strength on the upconverter efficiency is investigated

  6. Modeling of optical losses in graphene contacted CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Houshmand, Mohammad; Zandi, M. Hossein

    2016-09-01

    For the first time, an optical model is applied to superstrate configuration of CdS/CIGS thin film solar cells with graphene front/back contact (FC/BC) to simulate the loss in current density and efficiency. Graphene shows to be a great candidate to replace with the metallic BC transparent conductive oxides as the front electrode. Our model is based on the refractive index and extinction coefficient and takes into account the reflection and absorption in interfaces and layer’s thickness, respectively. CIGS cells with graphene as front electrode have a lower current density and efficiency than the one with graphene BC. However, the bifacial configuration shows a higher current density and efficiency, mostly because of a higher transmission rate. The interference effect was observed in simulation of transmission rate of hybrid cells representing that graphene can cause multiple reflection. We simulated the device parameters versus the ZnO layer’s thickness, which is essential for high quality interfaces. However, the simulation results are also consistent when CdS thickness is replaced with inorganic ZnO.

  7. Plasmonic versus dielectric enhancement in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Dühring, Maria B.; Asger Mortensen, N.; Sigmund, Ole

    2012-05-01

    Several studies have indicated that broadband absorption of thin-film solar cells can be enhanced by use of surface-plasmon induced resonances of metallic parts like strips or particles. The metallic parts may create localized modes or scatter incoming light to increase absorption in thin-film semiconducting material. For a particular case, we show that coupling to the same type of localized slab-waveguide modes can be obtained by a surface modulation consisting of purely dielectric strips. The purely dielectric device turns out to have a significantly higher broadband enhancement factor compared to its metallic counterpart. We show that the enhanced normalized short-circuit current for a cell with silicon strips can be increased 4 times compared to the best performance for strips of silver, gold, or aluminium. For this particular case, the simple dielectric grating may outperform its plasmonic counterpart due to the larger Ohmic losses associated with the latter.

  8. Polycrystalline Thin-Film Photovoltaic Technologies: Progress and Technical Issues

    SciTech Connect

    Ullal, H. S.

    2004-08-01

    Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for a thin-film CIGS solar cell and 16.5% for thin-film CdTe solar cell. A number of technical R&D issues related to CIS and CdTe have been identified. Thin-film power module efficiencies up to 13.4% has been achieved thus far. Tremendous progress has been made in the technology development for module fabrication, and multi-megawatt manufacturing facilities are coming on line with expansion plans in the next few years. Several 40-480 kW polycrystalline thin-film, grid-connected PV arrays have been deployed worldwide. Hot and humid testing is also under way to validate the long-term reliability of these emerging thin-film power products. The U.S. thin-film production (amorphous silicon[a-Si], CIS, CdTe) is expected to exceed 50 MW by the end of 2005.

  9. Optical and electrical characterization of CIGS thin films grown by electrodeposition route

    NASA Astrophysics Data System (ADS)

    Adel, Chihi; Fethi, Boujmil Mohamed; Brahim, Bessais

    2016-02-01

    In this paper, the electrochemical impedance spectroscopy was handled to study the electrochemical attitude of quaternary alloy Cu (In, Ga) Se2/Na2SO4 electrolyte interface. Subsequently, an annealing treatment was performed at various temperatures (250-400 °C). The material features of Cu (In, Ga) Se2 films are controlled by the percentage of gallium content. XRD studies showed three favorite orientations along the (112), (220), and (116) planes for all samples. The morphological and chemical composition studies exhibited Ga/(Ga + In) ratio ranging from 0.27 to 0.32, and RMS surface roughness was in the range 54.2-77.8 nm, respectively. The optical band gap energy of the CIGS alloys can be strongly controlled by adjusting gallium and indium concentrations. EIS measurement has been modeled by using an equivalent circuit. Mott-Schottky plot illustrates p-type conductivity of CIGS film with a carrier concentration around 1016 cm-3, a flat band potential V fb ranging from -0.68 to -0.57 V, and depletion layer thickness rises from 0.24 to 0.36 μm.

  10. Thin film solar cell including a spatially modulated intrinsic layer

    DOEpatents

    Guha, Subhendu; Yang, Chi-Chung; Ovshinsky, Stanford R.

    1989-03-28

    One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.

  11. Methods for fabricating thin film III-V compound solar cell

    DOEpatents

    Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

    2011-08-09

    The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

  12. Diode laser processed crystalline silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Varlamov, S.; Eggleston, B.; Dore, J.; Evans, R.; Ong, D.; Kunz, O.; Huang, J.; Schubert, U.; Kim, K. H.; Egan, R.; Green, M.

    2013-03-01

    Line-focus diode laser is applied to advance crystalline silicon thin-film solar cell technology. Three new processes have been developed: 1) defect annealing/dopant activation; 2) dopant diffusion; 3) liquid phase crystallisation of thin films. The former two processes are applied to either create a solar cell device from pre-crystallised films or improve its performance while reducing the maximum temperature experienced by substrate. The later process is applied to amorphous silicon films to obtain high crystal and electronic quality material for thin-film solar cells with higher efficiency potential. Defect annealing/dopant activation and dopant diffusion in a few micron thick poly-Si films are achieved by scanning with line-focus 808 nm diode laser beam at 15-24 kW/cm2 laser power and 2~6 ms exposure. Temperature profile in the film during the treatment is independent from laser power and exposure but determined by beam shape. Solar cell open-circuit voltages of about 500 mV after such laser treatments is similar or even higher than voltages after standard rapid-thermal treatments while the highest temperature experienced by glass is 300C lower. Amorphous silicon films can be melted and subsequently liquid-phase crystallised by a single scan of line laser beam at about 20 kW/cm2 power and 10-15 ms exposure. Solar cells made of laser-crystallised material achieve 557 mV opencircuit voltage and 8.4% efficiency. Electronic quality of such cells is consistent with efficiencies exceeding 13% and it is currently limited by research-level simplified cell metallisation.

  13. Development of sputtering systems for large-area deposition of CuIn1-xGaxSe1-ySy thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Dhere, Neelkanth G.; Gade, Vivek S.; Jahagirdar, Anant H.; Kadam, Ankur A.; Patil, Harshad P.; Kulkarni, Sachin S.

    2003-07-01

    CuIn1-xGaxSe1-ySy (CIGS) thin-film modules are expected to become cheaper than crystalline silicon modules within 5 yr. At present, commissioning and reaching full production of thin film modules is delayed because of nonavailability of turnkey manufacturing plants. Very few universities are conducting research on development of PV plants. CIGS thin-film solar cells are being prepared routinely at Florida Solar Energy Center (FSEC) on glass and metallic foil substrates for terrestrial and space applications. Earlier, the substrate size was limited to 3×3 cm2. This article presents results of development of large-area sputtering systems for preparation of large (15.2×15.2 cm2) CIGS thin-film solar cells. The facilities have the potential of serving as a nucleus of a pilot plant for fabrication of CIGS minimodules. Initial problems of bowing of the brass diaphragm, restriction of effective water flow and consequent heating of the target material were resolved by increasing the thickness of the backing plate and redesigning the structural members. Thickness uniformity was improved by modifying the magnetic field distribution in the middle 15 cm portion of the 10.2×30.5 cm2 magnetron sputtering sources by selectively removing nickel-coated soft-iron pieces at the rear. This resulted in Mo layer thickness uniformity of +/-3% over 10.2×10.2 cm2. The magnetic field was boosted at extremities to avoid precipitous ~15% drop beyond 10.2 cm. With this, thickness uniformities of +/-2.5% for Mo and +/-4.5% for ZnO over 12.7×10.2 cm2 have been achieved however with a continuing drop beyond 12.7 cm width. Modifying the magnetic field to achieve better distribution by preferentially removing soft irons pieces and also boosting of the magnetic field at the ends are two new concepts introduced and successfully utilized in this study. Scaling up of the large-area uniform deposition of metallic precursor layers was a challenging task. The efforts were directed towards obtaining

  14. Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Winans, Joshua David

    As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

  15. Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells.

    PubMed

    Hossain, Md Anower; Wang, Mingqing; Choy, Kwang-Leong

    2015-10-14

    Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc=0.518 V, jsc=28.79 mA cm(-2), fill factor=64.02%, and a promising power conversion efficiency of η=9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost.

  16. High efficiency nanostructured thin film solar cells for energy harvesting

    NASA Astrophysics Data System (ADS)

    Welser, Roger E.; Sood, Ashok K.; Lewis, Jay S.; Dhar, Nibir K.; Wijewarnasuriya, Priyalal S.

    2016-05-01

    Thin-film III-V materials are an attractive candidate material for solar energy harvesting devices capable of supplying portable and mobile power in both terrestrial and space environments. Nanostructured quantum well and quantum dot solar cells are being widely investigated as a means of extending infrared absorption and enhancing photovoltaic device performance. In this paper, we will review recent progress on realizing high-voltage InGaAs/GaAs quantum well solar cells that operate at or near the radiative limit of performance. These high-voltage nanostructured device designs provide a pathway to enhance the performance of existing device technologies, and can also be leveraged for next-generation solar cells.

  17. Thin-film Solar Cells for Space Applications

    NASA Technical Reports Server (NTRS)

    Lush, Gregory B.

    2003-01-01

    The proposed work supports MURED goals by fostering research and development activities at Fisk and UTEP which contribute substantially to NASA's mission, preparing faculty and students at Fisk and UTEP to successfully participate in the conventional, competitive research and education process, and increasing the number of students to successfully complete degrees in NASA related fields. The project also addresses directly a core need of NASA for space power and is consistent with the Core Responsibilities of the John Glenn Space Center. Current orbital missions are limited by radiation from high energy particles trapped in the Van Allen Belt because that solar radiation degrades cell performance by damaging the crystalline lattice. Some potential orbits have been inaccessible because the radiation is too severe. Thin-film solar cells, if they can be adapted for use in the unfriendly space environment, could open new orbits to satellites by providing a radiation hard source of power. The manned mission to Mars requires photovoltaic devices for both the trip there and as a power supply on the surface. Solar arrays using thin films offer a low power/weight ratio solution that provides reliable photovoltaic power.

  18. Recycling of high purity selenium from CIGS solar cell waste materials.

    PubMed

    Gustafsson, Anna M K; Foreman, Mark R StJ; Ekberg, Christian

    2014-10-01

    Copper indium gallium diselenide (CIGS) is a promising material in thin film solar cell production. To make CIGS solar cells more competitive, both economically and environmentally, in comparison to other energy sources, methods for recycling are needed. In addition to the generally high price of the material, significant amounts of the metals are lost in the manufacturing process. The feasibility of recycling selenium from CIGS through oxidation at elevated temperatures was therefore examined. During oxidation gaseous selenium dioxide was formed and could be separated from the other elements, which remained in solid state. Upon cooling, the selenium dioxide sublimes and can be collected as crystals. After oxidation for 1h at 800°C all of the selenium was separated from the CIGS material. Two different reduction methods for reduction of the selenium dioxide to selenium were tested. In the first reduction method an organic molecule was used as the reducing agent in a Riley reaction. In the second reduction method sulphur dioxide gas was used. Both methods resulted in high purity selenium. This proves that the studied selenium separation method could be the first step in a recycling process aimed at the complete separation and recovery of high purity elements from CIGS.

  19. Thin Film Solar Cells: Organic, Inorganic and Hybrid

    NASA Technical Reports Server (NTRS)

    Dankovich, John

    2004-01-01

    Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive

  20. Synthesis and characterization of copper antimony tin sulphide thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Ali, N.; Hussain, A.; Ahmed, R.; Wan Shamsuri, W. N.; Fu, Y. Q.

    2016-12-01

    Low price thin film modules based on Copper antimony tin sulphide (CATS) are introduced for solar harvesting to compete for the already developed compound semiconductors. Here, CATS thin films were deposited on soda lime glass by thermal evaporation technique followed by a rapid thermal annealing in an argon atmosphere. From Our XRD analysis, it was revealed that the annealed samples were poly-crystalline and their crystallinity was improved with increasing annealing temperature. The constituent elements and their corresponding chemical states were identified using X-ray photoelectron spectroscopy. The obtained optical band gap of 1.4 eV for CATS thin film is found nearly equal to GaAs - one of the highly efficient thin film material for solar cell technology. Furthermore, our observed good optical absorbance and low transmittance for the annealed CATS thin films in the visible region of light spectrum assured the aptness of the CATS thin films for solar cell applications.

  1. Lead Iodide Thin Film Crystallization Control for High-Performance and Stable Solution-Processed Perovskite Solar Cells.

    PubMed

    Yang, Lijun; Wang, Jingchuan; Leung, Wallace Woon-Fong

    2015-07-15

    PbI2 thin film crystallization control is a prerequisite of high-quality perovskite thin film for sequentially solution-processed perovskite solar cells. An efficient and simple method has been developed by adding HCl to improve perovskite thin film quality, and an efficiency of 15.2% is obtained. This approach improves coverage, uniformity, and stability of pervoskite thin film.

  2. Chemically Deposited Thin-Film Solar Cell Materials

    NASA Technical Reports Server (NTRS)

    Raffaelle, R.; Junek, W.; Gorse, J.; Thompson, T.; Harris, J.; Hehemann, D.; Hepp, A.; Rybicki, G.

    2005-01-01

    We have been working on the development of thin film photovoltaic solar cell materials that can be produced entirely by wet chemical methods on low-cost flexible substrates. P-type copper indium diselenide (CIS) absorber layers have been deposited via electrochemical deposition. Similar techniques have also allowed us to incorporate both Ga and S into the CIS structure, in order to increase its optical bandgap. The ability to deposit similar absorber layers with a variety of bandgaps is essential to our efforts to develop a multi-junction thin-film solar cell. Chemical bath deposition methods were used to deposit a cadmium sulfide (CdS) buffer layers on our CIS-based absorber layers. Window contacts were made to these CdS/CIS junctions by the electrodeposition of zinc oxide (ZnO). Structural and elemental determinations of the individual ZnO, CdS and CIS-based films via transmission spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive spectroscopy will be presented. The electrical characterization of the resulting devices will be discussed.

  3. High-efficiency cadmium-free Cu(In,Ga)Se{sub 2} thin-film solar cells with chemically deposited ZnS buffer layers

    SciTech Connect

    Nakada, Tokio; Furumi, Keisuke; Kunioka, Akio

    1999-10-01

    Cadmium-free Cu(In,Ga)Se{sub 2} (CIGS) thin-film solar cells with a MgF{sub 2}/ZnO:Al/CBD-ZnS/CIGS/Mo/SLG structure have been fabricated using chemical bath deposition (CBD)-ZnS buffer layers and high-quality CIGS absorber layers grown using molecular beam epitaxy (MBE) system. The use of CBD-ZnS, which is a wider band gap material than CBD-CdS, improved the quantum efficiency of fabricated cells at short wavelengths, leading to an increase in the short-circuit current. The best cell at present yielded an active area efficiency of 16.9% which is the highest value reported previously for Cd-free CIGS thin-film solar cells. The as-fabricated solar cells exhibited a reversible light-soaking effect under AM 1.5, 100 mW/cm{sup 2} illumination. This paper also presents a discussion of the issues relating to the use of the CBD-ZnS buffer material for improving device performance.

  4. High-efficiency heterojunction crystalline Si solar cell and optical splitting structure fabricated by applying thin-film Si technology

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kenji; Adachi, Daisuke; Uzu, Hisashi; Ichikawa, Mitsuru; Terashita, Toru; Meguro, Tomomi; Nakanishi, Naoaki; Yoshimi, Masashi; Hernández, José Luis

    2015-08-01

    Thin-film Si technology for solar cells has been developed for over 40 years. Improvements in the conversion efficiency and industrialization of thin-film Si solar cells have been realized through continuous research and development of the thin-film Si technology. The thin-film Si technology covers a wide range of fields such as fundamental understanding of the nature of thin-film Si, cell/module production, simulation, and reliability technologies. These technologies are also significant for solar cells other than the thin-film Si solar cells. Utilizing the highly developed thin-film Si solar cell technology, we have achieved ∼24% efficiency heterojunction crystalline Si solar cells using 6-in. wafers and >26% efficiency solar cells with an optical splitting structure. These results indicate that further improvement of thin-film Si technology and its synergy with crystalline Si solar cell technology will enable further improvement of solar cells with efficiencies above 26%.

  5. Non-ionizing energy loss calculations for modeling electron-induced degradation of Cu(In, Ga)Se2 thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Lu, Ming; Xu, Jing; Huang, Jian-Wei

    2016-09-01

    The lowest energies which make Cu, In, Ga, and Se atoms composing Cu(In, Ga)Se2 (CIGS) material displaced from their lattice sites are evaluated, respectively. The non-ionizing energy loss (NIEL) for electron in CIGS material is calculated analytically using the Mott differential cross section. The relation of the introduction rate (k) of the recombination centers to NIEL is modified, then the values of k at different electron energies are calculated. Degradation modeling of CIGS thin-film solar cells irradiated with various-energy electrons is performed according to the characterization of solar cells and the recombination centers. The validity of the modeling approach is verified by comparison with the experimental data. Project supported by the National Natural Science Foundation of China (Grant No. 11547151).

  6. Design, development and manufacture of high-efficiency low-cost solar modules based on CIGS PVICs

    NASA Astrophysics Data System (ADS)

    Eldada, Louay

    2010-02-01

    We describe the design, development and manufacture of solar power panels based on photovoltaic integrated circuits (PVICs) with high-quality high-uniformity Copper Indium Gallium Selenide (CIGS) thin films produced with the unique combination of low-cost ink-based and physical vapor deposition (PVD) based nanoengineered precursor thin films and a reactive transfer printing method. Reactive transfer is a two-stage process relying on chemical reaction between two separate precursor films to form CIGS, one deposited on the substrate and the other on a printing plate in the first stage. In the second stage, these precursors are brought into intimate contact and rapidly reacted under pressure in the presence of an electrostatic field while heat is applied. The use of two independent thin films provides the benefits of independent composition and flexible deposition technique optimization, and eliminates pre-reaction prior to the synthesis of CIGS. High quality CIGS with large grains on the order of several microns, and of preferred crystallographic orientation, are formed in just several minutes based on compositional and structural analysis by XRF, SIMS, SEM and XRD. Cell efficiencies of 14% and module efficiencies of 12% have been achieved using this method. When atmospheric pressure deposition of inks is utilized for the precursor films, the approach additionally provides lower energy consumption, higher throughput, and further reduced capital equipment cost with higher uptime.

  7. Copper gallium diselenide thin film absorber growth for solar cell device fabrication

    NASA Astrophysics Data System (ADS)

    Kaczynski, Ryan

    2007-12-01

    A custom-built migration-enhanced epitaxy reactor originally optimized for CuInSe2 (CIS) deposition was modified to grow gallium-containing compound semiconductor thin films, such as CuGaSe2 (CGS) and CuIn1-xGaxSe2 (CIGS). The addition of gallium allows for the manufacturing of solar cell absorber layers with wider band gaps. Three distinct growth recipes under several growth temperatures and a wide range of metal-composition ratios are used to deposit polycrystalline CGS thin films. The surface morphology of gallium-rich films is typically very uniform, with long needle-like grains when grown by the first recipe, a constant copper-rate process. In contrast, copper-rich films grown by this same recipe or by a modified three-stage process have island structures with very large grains embedded in a matrix region that possesses small grains. The surface morphology becomes more uniform and the grains in the matrix region become larger when a higher growth temperature is used. The third recipe, an emulated three-stage process, does not produce films with an island-matrix structure, and the grains are uniformly large. The highest conversion efficiency achieved for solar cells based on CGS is 5.3%, delivered by a copper-rich absorber deposited at the highest sustainable growth temperature of 491°C. This device has a large fill factor of 66%, but the open-circuit voltage of 0.48 V is lower than what is expected from a wide band-gap absorber. A set of CIGS solar cells was completely fabricated and characterized in-house. This led to the most efficient device produced from an absorber grown in our reactor, in the form of a 9% CIS solar cell featuring a one-micron film deposited at 491°C. Finally, a dynamic reactor model was created to describe the deposition environment in our epitaxial reactor. All relevant physical features are incorporated, including the cyclic motion of a rotating platen and the spatial distribution of the flux produced by three metal effusion sources

  8. Effect of post deposition annealing on the structure, morphology, optical and electrical properties of CuInGaSe2 thin films

    NASA Astrophysics Data System (ADS)

    Pugalenthi, A. S.; Balasundaraprabhu, R.; Prasanna, S.; Habibuddin, S.; Muthukumarasamy, N.; Mohan Rao, G.; Kannan, M. D.

    2016-12-01

    Polycrystalline copper indium gallium diselenide (CIGS) thin film is a favourable candidate for solar cell applications. In the present work the effect of post-deposition annealing on the structure, surface morphology, optical and electrical properties are discussed. Initially, gallium rich CIG thin films were deposited by RF magnetron sputtering followed by an indium rich CIG layer and subjected to selenization to realize CIGS stoichiometry. X-ray diffraction (XRD) results revealed the polycrystalline nature of the films with chalcopyrite structure having preferential orientation along <112> direction normal to the substrate. Optical properties of CIGS thin films were studied using UV-vis spectrophotometry and the band gap of CIGS was found to be around 1.15 eV. Hall Effect studies carried out on the CIGS thin films showed a linear dependence of conductivity with post deposition annealing. The elemental composition of the films was quantified using X-ray photoelectron spectroscopy (XPS) and the results are discussed.

  9. Systems and methods for solar cells with CIS and CIGS films made by reacting evaporated copper chlorides with selenium

    DOEpatents

    Albin, David S.; Noufi, Rommel

    2015-06-09

    Systems and methods for solar cells with CIS and CIGS films made by reacting evaporated copper chlorides with selenium are provided. In one embodiment, a method for fabricating a thin film device comprises: providing a semiconductor film comprising indium (In) and selenium (Se) upon a substrate; heating the substrate and the semiconductor film to a desired temperature; and performing a mass transport through vapor transport of a copper chloride vapor and se vapor to the semiconductor film within a reaction chamber.

  10. Recent advances in thin film CdTe solar cells

    SciTech Connect

    Ferekides, C.S.; Ceekala, V.; Dugan, K.; Killian, L.; Oman, D.; Swaminathan, R.; Morel, D.

    1996-01-01

    CdTe thin film solar cells have been fabricated on a variety of glass substrates (borosilicate and soda lime). The CdS films were deposited to a thickness of 500{endash}2000 A by the chemical bath deposition (CBD), rf sputtering, or close spaced sublimation (CSS) processes. The CdTe films were deposited by CSS in the temperature range of 450{endash}625{degree}C. The main objective of this work is to fabricate high efficiency solar cells using processes that can meet low cost manufacturing requirements. In an attempt to enhance the blue response of the CdTe cells, ZnS films have also been prepared (CBD, rf sputtering, CSS) as an alternative window layer to CdS. Device behavior has been found to be consistent with a recombination model. {copyright} {ital 1996 American Institute of Physics.}

  11. High efficiency copper ternary thin film solar cells

    SciTech Connect

    Basol, B.M.; Kapur, V.K. )

    1991-04-01

    This report describes work to develop a high efficiency, thin film CuInSe{sub 2} solar cell using a potentially low-cost process. The technique used in this development program is a two-stage process. The two-stage process involves depositing the metallic elements of the CuInSe{sub 2} compound (i.e., Cu and In) on a substrate in the form of stacked layers, and then selenizing this stacked metallic film in an atmosphere containing Se. Early results showed that the electrodeposition/selenization technique could yield CuInSe{sub 2} films with good electrical and optical properties on small-area substrates. This report concentrates on the later half of the research effort; this portion was directed toward developing a two-stage process using evaporated Cu-In layers. The selenization technique has the potential of yielding solar cells with efficiencies in excess of 15 percent. 7 refs., 12 figs.

  12. Commercial Development Of Ovonic Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Ovshinsky, Stanford R.

    1983-09-01

    subsequent paper) which has clearly demonstrated that the basic barrier to low-cost production has been broken through and that one can now speak realistically of delivering power directly from the sun for under a dollar per peak watt merely by making larger versions of this basic continuous web, large-area thin-film machine. We have made one square foot amorphous silicon alloy PIN devices with conversion efficiencies in the range of 7%, and in the laboratory, we have reported smaller area PIN de-vices in the 10% conversion efficiency range. In addition, much higher energy conversion efficiencies can be obtained within the same process by using multi-cell layered or tandem thin-film solar cell structures (see Figure 1). These devices exhibit enhanced efficiency by utilizing a wider range of the solar spectrum. Since the theoretical maximum efficiency for multi-cell structures is over 60%, one can certainly realistically anticipate the pro-duction of thin-film amorphous photovoltaic devices with efficiencies as high as 30%. Our production device is already a two-cell tandem, as we have solved not only the problems of interfacing the individual cell components but also the difficulties associated with a one foot square format deposited on a continuous web. Figure 2 shows a continuous roll of Ovonic solar cells. Realistic calculations for a three-cell tandem thin-film device using amorphous semiconductor alloys with 1.8eV, 1.5eV, and 1.0eV optical band gaps indicate that solar energy conversion efficiencies of 20-30% can be achieved.

  13. Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin Film Solar Cells (Presentation)

    SciTech Connect

    Pern, J.; Noufi, R.; Li, X.; DeHart, C.; To, B.

    2008-05-01

    The objectives are: (1) To achieve a high long-term performance reliability for the thin-film CIGS PV modules with more stable materials, device structure designs, and moisture-resistant encapsulation materials and schemes; (2) to evaluate the DH stability of various transparent conducting oxides (TCOs); (3) to identify the degradation mechanisms and quantify degradation rates; (4) to seek chemical and/or physical mitigation methods, and explore new materials. It's important to note that direct exposure to DH represents an extreme condition that a well-encapsulated thin film PV module may never experience.

  14. Quantum efficiency as a device-physics interpretation tool for thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Nagle, Timothy J.

    2007-12-01

    Thin-film solar cells made from CdTe and CIGS p-type absorbers are promising candidates for generating pollution-free electricity. The challenge faced by the thin-film photovoltaics (PV) community is to improve the electrical properties of devices, without straying from low-cost, industry-friendly techniques. This dissertation will focus on the use of quantum-efficiency (QE) measurements to deduce the device physics of thin-film devices, in the hope of improving electrical properties and efficiencies of PV materials. Photons which are absorbed, but not converted into electrical energy can modify the energy bands in the solar cell. Under illumination, photoconductivity in the CdS window layer can result in bands different from those in the dark. QE data presented here was taken under a variety of light-bias conditions. These results suggest that 0.10 sun of white-light bias incident on the CdS layer is usually sufficient to achieve accurate QE results. QE results are described by models based on carrier collection by drift and diffusion, and photon absorption. These models are sensitive to parameters such as carrier mobility and lifetime. Comparing calculated QE curves with experiments, it was determined that electron lifetimes in CdTe are less than 0.1 ns. Lifetime determinations also suggest that copper serves as a recombination center in CdTe. The spatial uniformity of QE results has been investigated with the LBIC apparatus, and several experiments are described which investigate cell uniformity. Electrical variations that occur in solar cells often occur in a nonuniform fashion, and can be detected with the LBIC apparatus. Studies discussed here include investigation of patterned deposition of Cu in back-contacts, the use of high-resistivity TCO layers to mitigate nonuniformity, optical effects, and local shunts. CdTe devices with transparent back contacts were also studied with LBIC, including those that received a strong bromine/dichrol/hydrazine (BDH) etch

  15. Cu(In,Ga)S2, Thin-Film Solar Cells Prepared by H2S Sulfurization of CuGa-In Precursor

    NASA Technical Reports Server (NTRS)

    Dhere, Neelkanth G.; Kulkarni, Shashank R.; Chavan, Sanjay S.; Ghongadi, Shantinath R.

    2005-01-01

    Thin-film CuInS2 solar cell is the leading candidate for space power because of bandgap near the optimum value for AM0 solar radiation outside the earth's atmosphere, excellent radiation hardness, and freedom from intrinsic degradation mechanisms unlike a-Si:H cells. Ultra-lightweight thin-film solar cells deposited on flexible polyimide plastic substrates such as Kapton(trademark), Upilex(trademark), and Apical(trademark) have a potential for achieving specific power of 1000 W/kg, while the state-of-art specific power of the present day solar cells is 66 W/kg. This paper describes the preparation of Cu-rich CuIn(sub 1-x)Ga(sub x)S(sub 2) (CIGS2) thin films and solar cells by a process of sulfurization of CuGa-In precursor similar to that being used for preparation of large-compact-grain CuIn(sub 1-x)Ga(sub x)Se2 thin films and efficient solar cells at FSEC PV Materials Lab.

  16. CdS thin film solar cells for terrestrial power

    NASA Technical Reports Server (NTRS)

    Shirland, F. A.

    1975-01-01

    The development of very low cost long lived Cu2S/CdS thin film solar cells for large scale energy conversion is reported. Excellent evaporated metal grid patterns were obtained using a specially designed aperture mask. Vacuum evaporated gold and copper grids of 50 lines per inch and 1 micron thickness were adequate electrically for the fine mesh contacting grid. Real time roof top sunlight exposure tests of encapsulated CdS cells showed no loss in output after 5 months. Accelerated life testing of encapsulated cells showed no loss of output power after 6 months of 12 hour dark-12 hour AMI illumination cycles at 40 C, 60 C, 80 C and 100 C temperatures. However, the cells changed their basic parameters, such as series and shunt resistance and junction capacitance.

  17. Circuit analysis method for thin-film solar cell modules

    NASA Technical Reports Server (NTRS)

    Burger, D. R.

    1985-01-01

    The design of a thin-film solar cell module is dependent on the probability of occurrence of pinhole shunt defects. Using known or assumed defect density data, dichotomous population statistics can be used to calculate the number of defects expected in a module. Probability theory is then used to assign the defective cells to individual strings in a selected series-parallel circuit design. Iterative numerical calculation is used to calcuate I-V curves using cell test values or assumed defective cell values as inputs. Good and shunted cell I-V curves are added to determine the module output power and I-V curve. Different levels of shunt resistance can be selected to model different defect levels.

  18. Circuit analysis method for thin-film solar cell modules

    NASA Astrophysics Data System (ADS)

    Burger, D. R.

    1985-12-01

    The design of a thin-film solar cell module is dependent on the probability of occurrence of pinhole shunt defects. Using known or assumed defect density data, dichotomous population statistics can be used to calculate the number of defects expected in a module. Probability theory is then used to assign the defective cells to individual strings in a selected series-parallel circuit design. Iterative numerical calculation is used to calcuate I-V curves using cell test values or assumed defective cell values as inputs. Good and shunted cell I-V curves are added to determine the module output power and I-V curve. Different levels of shunt resistance can be selected to model different defect levels.

  19. Photoelectric processes in CdSe thin film solar cells

    SciTech Connect

    Rickus, E.

    1984-05-01

    Efficiencies exceeding 7 percent have been achieved with CdSe/ZnSe/Au thin film solar cells. The collection efficiency of carriers in highly oriented CdSe films is near unity, resulting in short circuit current densities comparable to values observed on single crystalline cells. Recombination of carriers at the CdSe/ZnSe interface plays a minor role. CdSe /SUB x/ Te /SUB 1-x/ cells show the potential of enhanced short circuit current densities. Crystallographic and chemical inhomogeneities have a major influence on their performance. The comparison of photoelectrochemical cells based on CdSe single crystals and on polycrystalline layers demonstrates the photovoltaic quality of our CdSe films.

  20. Recycling of high purity selenium from CIGS solar cell waste materials

    SciTech Connect

    Gustafsson, Anna M.K. Foreman, Mark R.StJ.; Ekberg, Christian

    2014-10-15

    Highlights: • A new method for recycling of selenium from CIGS solar cell materials is presented. • Separation of selenium as selenium dioxide after heating in oxygen atmosphere. • Complete selenium separation after oxidation of <63 μm particles at 800 °C for 1 h. • After reduction of selenium dioxide the selenium purity was higher than 99.999 wt%. - Abstract: Copper indium gallium diselenide (CIGS) is a promising material in thin film solar cell production. To make CIGS solar cells more competitive, both economically and environmentally, in comparison to other energy sources, methods for recycling are needed. In addition to the generally high price of the material, significant amounts of the metals are lost in the manufacturing process. The feasibility of recycling selenium from CIGS through oxidation at elevated temperatures was therefore examined. During oxidation gaseous selenium dioxide was formed and could be separated from the other elements, which remained in solid state. Upon cooling, the selenium dioxide sublimes and can be collected as crystals. After oxidation for 1 h at 800 °C all of the selenium was separated from the CIGS material. Two different reduction methods for reduction of the selenium dioxide to selenium were tested. In the first reduction method an organic molecule was used as the reducing agent in a Riley reaction. In the second reduction method sulphur dioxide gas was used. Both methods resulted in high purity selenium. This proves that the studied selenium separation method could be the first step in a recycling process aimed at the complete separation and recovery of high purity elements from CIGS.

  1. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate

    NASA Astrophysics Data System (ADS)

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-07-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination.

  2. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate

    PubMed Central

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-01-01

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination. PMID:27435899

  3. Highly efficient single-junction GaAs thin-film solar cell on flexible substrate.

    PubMed

    Moon, Sunghyun; Kim, Kangho; Kim, Youngjo; Heo, Junseok; Lee, Jaejin

    2016-07-20

    There has been much interest in developing a thin-film solar cell because it is lightweight and flexible. The GaAs thin-film solar cell is a top contender in the thin-film solar cell market in that it has a high power conversion efficiency (PCE) compared to that of other thin-film solar cells. There are two common structures for the GaAs solar cell: n (emitter)-on-p (base) and p-on-n. The former performs better due to its high collection efficiency because the electron diffusion length of the p-type base region is much longer than the hole diffusion length of the n-type base region. However, it has been limited to fabricate highly efficient n-on-p single-junction GaAs thin film solar cell on a flexible substrate due to technical obstacles. We investigated a simple and fast epitaxial lift-off (ELO) method that uses a stress originating from a Cr/Au bilayer on a 125-μm-thick flexible substrate. A metal combination of AuBe/Pt/Au is employed as a new p-type ohmic contact with which an n-on-p single-junction GaAs thin-film solar cell on flexible substrate was successfully fabricated. The PCE of the fabricated single-junction GaAs thin-film solar cells reached 22.08% under air mass 1.5 global illumination.

  4. Structures, optical absorption and electrical properties of pulsed-laser-deposited CuIn0.8Ga0.2Se2 thin films and their use in CIGS/PCBM photovoltaic structures

    NASA Astrophysics Data System (ADS)

    Zhao, Yu; Wu, JiaDa; Xu, Ning

    2016-10-01

    Polycrystalline CuIn0.8Ga0.2Se2 (CIGS) thin films are deposited on ITO-glass substrates at different substrate temperatures by pulsed laser deposition using a Nd:YAG laser. The crystallinity of the as-deposited CIGS films significantly improved as the substrate temperature increased. The experimental results indicate that the ordered defect compound model is also applicable to the CIGS films deposited in these experiments. All the as-deposited CIGS thin films show absorption coefficients of 105 cm-1 magnitude in a wavelength range of 400-900 nm. The CIGS thin films deposited at substrate temperatures lower than 400 °C exhibit n-type conductivity while those deposited at a substrate temperature of 500 °C display p-type conductivity. The CIGS/phenyl-C61-butyric acid methyl ester (PCBM) photovoltaic structure, with a CIGS layer as the only absorber, demonstrates an apparent photovoltaic response with a short circuit current density of 0.389 mA cm-2 and an open circuit voltage of 0.327 V.

  5. The German Joint Project "Flexible CIGSe Thin Film Solar Cells for Space Flight

    NASA Astrophysics Data System (ADS)

    Zajac, Kai; Brunner, Sebastian; John, Ralf; Kaufmann, Christian A.; Otte, Karsten; Rahm, Andreas; Kessler, Friedrich

    2008-09-01

    The purpose of the presented joint project is the development and verification of a flexible, lightweight and highly efficient Cu(In,Ga)Se2 (CIGSe) thin film solar cell technology on polyimide foil substrate for use in space. Due to the worldwide leading present German activities on the field of chalcopyrite based thin film solar cells a harmonisation of resources shall push this development. Furthermore, this project supports the European Space Agency (ESA) program for the development of thin film solar cell technology for space applications. Recent results of substrate evaluation and CIGSe solar cell and module manufacturing on polyimide foil substrate are presented.

  6. Molecular solution processing of metal chalcogenide thin film solar cells

    NASA Astrophysics Data System (ADS)

    Yang, Wenbing

    The barrier to utilize solar generated electricity mainly comes from their higher cost relative to fossil fuels. However, innovations with new materials and processing techniques can potentially make cost effective photovoltaics. One such strategy is to develop solution processed photovoltaics which avoid the expensive vacuum processing required by traditional solar cells. The dissertation is mainly focused on two absorber material system for thin film solar cells: chalcopyrite CuIn(S,Se)2 (CISS) and kesterite Cu2ZnSn(S,Se) 4 organized in chronological order. Chalcopyrite CISS is a very promising material. It has been demonstrated to achieve the highest efficiency among thin film solar cells. Scaled-up industry production at present has reached the giga-watt per year level. The process however mainly relies on vacuum systems which account for a significant percentage of the manufacturing cost. In the first section of this dissertation, hydrazine based solution processed CISS has been explored. The focus of the research involves the procedures to fabricate devices from solution. The topics covered in Chapter 2 include: precursor solution synthesis with a focus on understanding the solution chemistry, CISS absorber formation from precursor, properties modification toward favorable device performance, and device structure innovation toward tandem device. For photovoltaics to have a significant impact toward meeting energy demands, the annual production capability needs to be on TW-level. On such a level, raw materials supply of rare elements (indium for CIS or tellurium for CdTe) will be the bottleneck limiting the scalability. Replacing indium with zinc and tin, earth abundant kesterite CZTS exhibits great potential to reach the goal of TW-level with no limitations on raw material availability. Chapter 3 shows pioneering work towards solution processing of CZTS film at low temperature. The solution processed devices show performances which rival vacuum

  7. Amorphous silicon thin films: The ultimate lightweight space solar cell

    NASA Technical Reports Server (NTRS)

    Vendura, G. J., Jr.; Kruer, M. A.; Schurig, H. H.; Bianchi, M. A.; Roth, J. A.

    1994-01-01

    Progress is reported with respect to the development of thin film amorphous (alpha-Si) terrestrial solar cells for space applications. Such devices promise to result in very lightweight, low cost, flexible arrays with superior end of life (EOL) performance. Each alpha-Si cell consists of a tandem arrangement of three very thin p-i-n junctions vapor deposited between film electrodes. The thickness of this entire stack is approximately 2.0 microns, resulting in a device of negligible weight, but one that must be mechanically supported for handling and fabrication into arrays. The stack is therefore presently deposited onto a large area (12 by 13 in), rigid, glass superstrate, 40 mil thick, and preliminary space qualification testing of modules so configured is underway. At the same time, a more advanced version is under development in which the thin film stack is transferred from the glass onto a thin (2.0 mil) polymer substrate to create large arrays that are truly flexible and significantly lighter than either the glassed alpha-Si version or present conventional crystalline technologies. In this paper the key processes for such effective transfer are described. In addition, both glassed (rigid) and unglassed (flexible) alpha-Si cells are studied when integrated with various advanced structures to form lightweight systems. EOL predictions are generated for the case of a 1000 W array in a standard, 10 year geosynchronous (GEO) orbit. Specific powers (W/kg), power densities (W/sq m) and total array costs ($/sq ft) are compared.

  8. Amorphous silicon thin films: The ultimate lightweight space solar cell

    SciTech Connect

    Vendura, G.J. Jr.; Kruer, M.A.; Schurig, H.H.; Bianchi, M.A.; Roth, J.A.

    1994-09-01

    Progress is reported with respect to the development of thin film amorphous (alpha-Si) terrestrial solar cells for space applications. Such devices promise to result in very lightweight, low cost, flexible arrays with superior end of life (EOL) performance. Each alpha-Si cell consists of a tandem arrangement of three very thin p-i-n junctions vapor deposited between film electrodes. The thickness of this entire stack is approximately 2.0 microns, resulting in a device of negligible weight, but one that must be mechanically supported for handling and fabrication into arrays. The stack is therefore presently deposited onto a large area (12 by 13 in), rigid, glass superstrate, 40 mil thick, and preliminary space qualification testing of modules so configured is underway. At the same time, a more advanced version is under development in which the thin film stack is transferred from the glass onto a thin (2.0 mil) polymer substrate to create large arrays that are truly flexible and significantly lighter than either the glassed alpha-Si version or present conventional crystalline technologies. In this paper the key processes for such effective transfer are described. In addition, both glassed (rigid) and unglassed (flexible) alpha-Si cells are studied when integrated with various advanced structures to form lightweight systems. EOL predictions are generated for the case of a 1000 W array in a standard, 10 year geosynchronous (GEO) orbit. Specific powers (W/kg), power densities (W/sq m) and total array costs ($/sq ft) are compared.

  9. Plasmonic nanodot array optimization on organic thin film solar cells using anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Bae, Kyuyoung; Kim, Kyoungsik

    2013-09-01

    The fabrication method of plasmonic nanodots on ITO or nc-ZnO substrate has been developed to improve the efficiency of organic thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of metallic nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of organic thin film solar cells. It is found that optical properties of the organic thin film solar cells are improved by finding optimization values of the structural parameters of the metallic nanodot array.

  10. Progress in polycrystalline thin-film solar cells

    SciTech Connect

    Zweibel, K; Hermann, A; Mitchell, R

    1983-07-01

    Photovoltaic devices based on several polycrystalline thin-film materials have reached near and above 10% sunlight-to-electricity conversion efficiencies. This paper examines the various polycrystalline thin-film PV materials including CuInSe/sub 2/ and CdTe in terms of their material properties, fabrication techniques, problems, and potentials.

  11. Thin film, concentrator and multijunction space solar cells: Status and potential

    NASA Technical Reports Server (NTRS)

    Flood, Dennis J.

    1991-01-01

    Recent, rapid advances in a variety of solar cell technologies offer the potential for significantly enhancing, or enabling entirely new, mission capabilities. Thin film solar cells are of particular interest in that regard. A review is provided of the status of those thin film cell technologies of interest for space applications, and the issues to be resolved before mission planners can consider them. A short summary is also given of recent developments in concentrator and multijunction space solar cell and array technology.

  12. Thin film, concentrator, and multijunction space solar cells: Status and potential

    NASA Technical Reports Server (NTRS)

    Flood, Dennis J.

    1991-01-01

    Recent, rapid advances in a variety of solar cell technologies offer the potential for significantly enhancing, or enabling entirely new, mission capabilities. Thin film solar cells are of particular interest. A review is provided of the status of those thin film cell technologies of interest for space applications, and the issues to be resolved before mission planners can consider them. A short summary of recent developments in concentrator and multijunction space solar cell and array technology is given.

  13. Recent Progress Towards Space Applications Of Thin Film Solar Cells- The German Joint Project 'Flexible CIGSE Thin Film Solar Cells For Space Flight' And OOV

    NASA Astrophysics Data System (ADS)

    Brunner, Sebastian; Zajac, Kai; Nadler, Michael; Seifart, Klaus; Kaufmann, Christian A.; Caballero, Raquel; Schock, Hans-Werner; Hartmann, Lars; Otte, Karten; Rahm, Andreas; Scheit, Christian; Zachmann, Hendrick; Kessler, Friedrich; Wurz, Roland; Schulke, Peter

    2011-10-01

    A group of partners from an academic and industrial background are developing a flexible Cu(In,Ga)Se2 (CIGSe) thin film solar cell technology on a polyimide substrate that aims to be a future alternative to current rigid solar cell technologies for space applications. In particular on missions with high radiation volumes, the superior tolerance of chalcopyrite based thin film solar cell (TFSC) technologies with respect to electron and proton radiation, when compared to the established Si- or III-V based technologies, can be advantageous. Of all thin film technologies, those based on CIGSe have the highest potential to reach attractive photovoltaic conversion efficiencies and combine these with low weight in order to realize high power densities on solar cell and generator level. The use of a flexible substrate ensures a high packing density. A working demonstrator is scheduled for flight this year.

  14. Chemical Vapor Deposition for Ultra-lightweight Thin-film Solar Arrays for Space

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Jin, Michael H.; Lau, Janice E.; Harris, Jerry D.; Cowen, Jonathan E.; Duraj, Stan A.

    2002-01-01

    The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. A key technical issues outlined in the 2001 U.S. Photovoltaic Roadmap, is the need to develop low cost, high throughput manufacturing for high-efficiency thin film solar cells. At NASA GRC we have focused on the development of new single-source-precursors (SSPs) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV devices.

  15. Utility of Thin-Film Solar Cells on Flexible Substrates for Space Power

    NASA Technical Reports Server (NTRS)

    Dickman, J. E.; Hepp, A. F.; Morel, D. L.; Ferekides, C. S.; Tuttle, J. R.; Hoffman, D. J.; Dhere, N. G.

    2004-01-01

    The thin-film solar cell program at NASA GRC is developing solar cell technologies for space applications which address two critical metrics: specific power (power per unit mass) and launch stowed volume. To be competitive for many space applications, an array using thin film solar cells must significantly increase specific power while reducing stowed volume when compared to the present baseline technology utilizing crystalline solar cells. The NASA GRC program is developing two approaches. Since the vast majority of the mass of a thin film solar cell is in the substrate, a thin film solar cell on a very lightweight flexible substrate (polymer or metal films) is being developed as the first approach. The second approach is the development of multijunction thin film solar cells. Total cell efficiency can be increased by stacking multiple cells having bandgaps tuned to convert the spectrum passing through the upper cells to the lower cells. Once developed, the two approaches will be merged to yield a multijunction, thin film solar cell on a very lightweight, flexible substrate. The ultimate utility of such solar cells in space require the development of monolithic interconnections, lightweight array structures, and ultra-lightweight support and deployment techniques.

  16. Thin film multilayer filters for solar EUV telescopes.

    PubMed

    Chkhalo, N I; Drozdov, M N; Kluenkov, E B; Kuzin, S V; Lopatin, A Ya; Luchin, V I; Salashchenko, N N; Tsybin, N N; Zuev, S Yu

    2016-06-10

    Al, with a passband in the wavelength range of 17-60 nm, and Zr, with a passband in the wavelength range of 6.5-17 nm, thin films on a support grid or support membrane are frequently used as UV, visible, and near-IR blocking filters in solar observatories. Although they possess acceptable optical performance, these filters also have some shortcomings such as low mechanical strength and low resistance to oxidation. These shortcomings hinder meeting the requirements for filters of future telescopes. We propose multilayer thin film filters on the basis of Al, Zr, and other materials with improved characteristics. It was demonstrated that stretched multilayer films on a support grid with a mesh size up to 5 mm can withstand vibration loads occurring during spacecraft launch. A large mesh size is preferable for filters of high-resolution solar telescopes, since it allows image distortion caused by light diffraction on the support grid to be avoided. We have investigated the thermal stability of Al/Si and Zr/Si multilayers assuming their possible application as filters in the Intergelioprobe project, in which the observation of coronal plasma will take place close to the Sun. Zr/Si films show high thermal stability and may be used as blocking filters in the wavelength range of 12.5-17 nm. Al/Si films show lower thermal stability: a significant decrease in the film's transmission in the EUV spectral range and an increase in the visible spectrum have been observed. We suppose that the low thermal stability of Al/Si films restricts their application in the Intergelioprobe project. Thus, there is a lack of filters for the wavelength range of λ>17  nm. Be/Si and Cr/Si filters have been proposed for the wavelength range near 30.4 nm. Although these filters have lower transparency than Al/Si, they are superior in thermal stability. Multilayer Sc/Al filters with relatively high transmission at a wavelength of 58.4 nm (HeI line) and simultaneously sufficient rejection in the

  17. Cocktails of paste coatings for performance enhancement of CuInGaS(2) thin-film solar cells.

    PubMed

    An, Hee Sang; Cho, Yunae; Park, Se Jin; Jeon, Hyo Sang; Hwang, Yun Jeong; Kim, Dong-Wook; Min, Byoung Koun

    2014-01-22

    To fabricate low-cost and printable wide-bandgap CuInxGa1-xS2 (CIGS) thin-film solar cells, a method based on a precursor solution was developed. In particular, under this method, multiple coatings with two pastes with different properties (e.g., viscosity) because of the different binder materials added were applied. Paste A could form a thin, dense layer enabling a high-efficiency solar cell but required several coating and drying cycles for the desired film thickness. On the other hand, paste B could easily form one-micrometer-thick films by means of a one-time spin-coating process but the porous microstructure limited the solar cell performance. Three different configurations of the CIGS films (A + B, B + A, and A + B + A) were realized by multiple coatings with the two pastes to find the optimal stacking configuration for a combination of the advantages of each paste. Solar cell devices using these films showed a notable difference in their photovoltaic characteristics. The bottom dense layer increased the minority carrier diffusion length and enhanced the short-circuit current. The top dense layer could suppress interface recombination but exhibited a low optical absorption, thereby decreasing the photocurrent. As a result, the A + B configuration could be suggested as a desirable simple stacking structure. The solar cell with A + B coating showed a highly improved efficiency (4.66%) compared to the cell with a film prepared by paste B only (2.90%), achieved by simple insertion of a single thin (200 nm), dense layer between the Mo back contact and a thick porous CIGS layer.

  18. Nano-photonic Light Trapping In Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Callahan, Dennis M., Jr.

    Over the last several decades there have been significant advances in the study and understanding of light behavior in nanoscale geometries. Entire fields such as those based on photonic crystals, plasmonics and metamaterials have been developed, accelerating the growth of knowledge related to nanoscale light manipulation. Coupled with recent interest in cheap, reliable renewable energy, a new field has blossomed, that of nanophotonic solar cells. In this thesis, we examine important properties of thin-film solar cells from a nanophotonics perspective. We identify key differences between nanophotonic devices and traditional, thick solar cells. We propose a new way of understanding and describing limits to light trapping and show that certain nanophotonic solar cell designs can have light trapping limits above the so called ray-optic or ergodic limit. We propose that a necessary requisite to exceed the traditional light trapping limit is that the active region of the solar cell must possess a local density of optical states (LDOS) higher than that of the corresponding, bulk material. Additionally, we show that in addition to having an increased density of states, the absorber must have an appropriate incoupling mechanism to transfer light from free space into the optical modes of the device. We outline a portfolio of new solar cell designs that have potential to exceed the traditional light trapping limit and numerically validate our predictions for select cases. We emphasize the importance of thinking about light trapping in terms of maximizing the optical modes of the device and efficiently coupling light into them from free space. To further explore these two concepts, we optimize patterns of superlattices of air holes in thin slabs of Si and show that by adding a roughened incoupling layer the total absorbed current can be increased synergistically. We suggest that the addition of a random scattering surface to a periodic patterning can increase incoupling by

  19. Review of thin film solar cell technology and applications for ultra-light spacecraft solar arrays

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    1991-01-01

    Developments in thin-film amorphous and polycrystalline photovoltaic cells are reviewed and discussed with a view to potential applications in space. Two important figures of merit are discussed: efficiency (i.e., what fraction of the incident solar energy is converted to electricity), and specific power (power to weight ratio).

  20. A Parametric Assessment of the Mission Applicability of Thin-film Solar Arrays

    NASA Technical Reports Server (NTRS)

    Hoffman, David J.

    2002-01-01

    Results are presented from a parametric assessment of the applicability and spacecraft-level impacts of very lightweight thin-film solar arrays with relatively large deployed areas for representative space missions. The most and least attractive features of thin-film solar arrays are briefly discussed. A calculation is then presented illustrating that from a solar array alone mass perspective, larger arrays with less efficient but lighter thin-film solar cells can weigh less than smaller arrays with more efficient but heavier crystalline cells. However, a spacecraft-level systems assessment must take into account the additional mass associated with solar array deployed area: the propellant needed to desaturate the momentum accumulated from area-related disturbance torques and to perform aerodynamic drag makeup reboost. The results for such an assessment are presented for a representative low Earth orbit (LEO) mission, as a function of altitude and mission life, and a geostationary Earth orbit (GEO) mission. Discussion of the results includes a list of specific mission types most likely to benefit from using thin-film arrays. The presentation concludes with a list of issues to be addressed prior to use of thin-film solar arrays in space and the observation that with their unique characteristics, very lightweight arrays using efficient, thin film cells on flexible substrates may become the best array option for a subset of Earth orbiting and deep space missions.

  1. Dual-Layer Nanostructured Flexible Thin-Film Amorphous Silicon Solar Cells with Enhanced Light Harvesting and Photoelectric Conversion Efficiency.

    PubMed

    Lin, Yinyue; Xu, Zhen; Yu, Dongliang; Lu, Linfeng; Yin, Min; Tavakoli, Mohammad Mahdi; Chen, Xiaoyuan; Hao, Yuying; Fan, Zhiyong; Cui, Yanxia; Li, Dongdong

    2016-05-04

    Three-dimensional (3-D) structures have triggered tremendous interest for thin-film solar cells since they can dramatically reduce the material usage and incident light reflection. However, the high aspect ratio feature of some 3-D structures leads to deterioration of internal electric field and carrier collection capability, which reduces device power conversion efficiency (PCE). Here, we report high performance flexible thin-film amorphous silicon solar cells with a unique and effective light trapping scheme. In this device structure, a polymer nanopillar membrane is attached on top of a device, which benefits broadband and omnidirectional performances, and a 3-D nanostructure with shallow dent arrays underneath serves as a back reflector on flexible titanium (Ti) foil resulting in an increased optical path length by exciting hybrid optical modes. The efficient light management results in 42.7% and 41.7% remarkable improvements of short-circuit current density and overall efficiency, respectively. Meanwhile, an excellent flexibility has been achieved as PCE remains 97.6% of the initial efficiency even after 10 000 bending cycles. This unique device structure can also be duplicated for other flexible photovoltaic devices based on different active materials such as CdTe, Cu(In,Ga)Se2 (CIGS), organohalide lead perovskites, and so forth.

  2. Optimized laser patterning for high performance Cu(In,Ga)Se2 thin-film solar modules

    NASA Astrophysics Data System (ADS)

    Burn, Andreas; Muralt, Martin; Witte, Reiner; Buecheler, Stephan; Nishiwaki, Shiro; Krainer, Lukas; Spuehler, Gabriel J.; Romano, Valerio

    2014-03-01

    The thin-film solar cell market has seen a period of consolidation during the last years and many involved companies were forced to stop production due to increasing price pressure from competing cell technologies. Today, thin-film solar industry is gaining momentum again. Especially Cu(In,Ga)Se2 technology evolves at high pace fired by recently achieved record efficiencies of 20.4 percent on flexible polyimide substrate [1] and 20.8 percent on glass substrate [2]. Fresh companies are preparing market entry with matured products and manufacturing technology suitable for high-volume and high-throughput production. Among these key-enabling technologies is laser patterning for cell-to-cell interconnects. Several research groups worked on efficient and reliable laser processes that are now ready for the industrial assessment. Here we present a set of work-horse processes for P1, P2 and P3 scribing of CIGS cells on glass substrate. Optimized parameters are presented for 532 nm and 1064 nm using 50 ps pulses from an all-in-fiber laser system. We further demonstrate the successful realization of functional 8-cell modules with a reduced "dead-zone" width of 70±5 μm and high efficiencies. The certified efficiency of 16.6 percent for our low-dead-zone champion module confirms the observation that shrinking of interconnects has no adverse effects on their electrical quality.

  3. Advances in thin-film solar cells for lightweight space photovoltaic power

    SciTech Connect

    Landis, G.A.; Bailey, S.G.; Flood, D.J.

    1989-01-01

    The present stature and current research directions of photovoltaic arrays as primary power systems for space are reviewed. There have recently been great advances in the technology of thin-film solar cells for terrestrial applications. In a thin-film solar cell the thickness of the active element is only a few microns; transfer of this technology to space arrays could result in ultralow-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe2) and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon:hydrogen and alloys. The best experimental efficiency on thin-film solar cells to date is 12 percent AMO for CuInSe2. This efficiency is likely to be increased in the next few years. The radiation tolerance of thin-film materials is far greater than that of single-crystal materials. CuInSe2 shows no degradation when exposed to 1 MeV electrons. Experimental evidence also suggests that most of all of the radiation damage on thin-films can be removed by a low temperature anneal. The possibility of thin-film multibandgap cascade solar cells is discussed, including the tradeoffs between monolithic and mechanically stacked cells. The best current efficiency for a cascade is 12.5 percent AMO for an amorphous silicon on CuInSe2 multibandgap combination. Higher efficiencies are expected in the future. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovolatic arrays may be a mission-enabling technology.

  4. Advances in thin-film solar cells for lightweight space photovoltaic power

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Bailey, Sheila G.; Flood, Dennis J.

    1989-01-01

    The present stature and current research directions of photovoltaic arrays as primary power systems for space are reviewed. There have recently been great advances in the technology of thin-film solar cells for terrestrial applications. In a thin-film solar cell the thickness of the active element is only a few microns; transfer of this technology to space arrays could result in ultralow-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper-indium selenide (CuInSe2) and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon:hydrogen and alloys. The best experimental efficiency on thin-film solar cells to date is 12 percent AMO for CuIn Se2. This efficiency is likely to be increased in the next few years. The radiation tolerance of thin-film materials is far greater than that of single-crystal materials. CuIn Se2 shows no degradation when exposed to 1 MeV electrons. Experimental evidence also suggests that most of all of the radiation damage on thin-films can be removed by a low temperature anneal. The possibility of thin-film multibandgap cascade solar cells is discussed, including the tradeoffs between monolithic and mechanically stacked cells. The best current efficiency for a cascade is 12.5 percent AMO for an amorphous silicon on CuInSe2 multibandgap combination. Higher efficiencies are expected in the future. For several missions, including solar-electric propulsion, a manned Mars mission, and lunar exploration and manufacturing, thin-film photovolatic arrays may be a mission-enabling technology.

  5. Influence of CuxS back contact on CdTe thin film solar cells

    NASA Astrophysics Data System (ADS)

    Zhi, Lei; Lianghuan, Feng; Guanggen, Zeng; Wei, Li; Jingquan, Zhang; Lili, Wu; Wenwu, Wang

    2013-01-01

    We present a detailed study on CuxS polycrystalline thin films prepared by chemical bath method and utilized as back contact material for CdTe solar cells. The characteristics of the films deposited on Si-substrate are studied by XRD. The results show that as-deposited CuxS thin film is in an amorphous phase while after annealing, samples are in polycrystalline phases with increasing temperature. The thickness of CuxS thin films has great impact on the performance of CdS/CdTe solar cells. When the thickness of the film is about 75 nm the performance of CdS/CdTe thin film solar cells is found to be the best. The energy conversion efficiency can be higher than 12.19%, the filling factor is higher than 68.82% and the open-circuit voltage is more than 820 mV.

  6. Toward omnidirectional light absorption by plasmonic effect for high-efficiency flexible nonvacuum Cu(In,Ga)Se2 thin film solar cells.

    PubMed

    Chen, Shih-Chen; Chen, Yi-Ju; Chen, Wei Ting; Yen, Yu-Ting; Kao, Tsung Sheng; Chuang, Tsung-Yeh; Liao, Yu-Kuang; Wu, Kaung-Hsiung; Yabushita, Atsushi; Hsieh, Tung-Po; Charlton, Martin D B; Tsai, Din Ping; Kuo, Hao-Chung; Chueh, Yu-Lun

    2014-09-23

    We have successfully demonstrated a great advantage of plasmonic Au nanoparticles for efficient enhancement of Cu(In,Ga)Se2(CIGS) flexible photovoltaic devices. The incorporation of Au NPs can eliminate obstacles in the way of developing ink-printing CIGS flexible thin film photovoltaics (TFPV), such as poor absorption at wavelengths in the high intensity region of solar spectrum, and that occurs significantly at large incident angle of solar irradiation. The enhancement of external quantum efficiency and photocurrent have been systematically analyzed via the calculated electromagnetic field distribution. Finally, the major benefits of the localized surface plasmon resonances (LSPR) in visible wavelength have been investigated by ultrabroadband pump-probe spectroscopy, providing a solid evidence on the strong absorption and reduction of surface recombination that increases electron-hole generation and improves the carrier transportation in the vicinity of pn-juction.

  7. Mechanism of optical absorption enhancement in thin film organic solar cells with plasmonic metal nanoparticles.

    PubMed

    Qu, Di; Liu, Fang; Huang, Yidong; Xie, Wanlu; Xu, Qi

    2011-11-21

    The optical absorption enhancement in thin film organic solar cells (OSCs) with plasmonic metal nanoparticles (NPs) has been studied by means of finite element method with a three-dimension model. It is found that significant plasmonic enhancement of above 100% can be obtained by introducing Ag-NPs at the interface between P3HT:PCBM active layer and PEDOT:PSS anode layer. This enhancement is even larger than that with Ag-NPs totally embedded in the P3HT:PCBM active layer of thin film OSCs. Furthermore, the enhancement mechanism of Ag-NPs at different positions of thin film OSCs is investigated.

  8. Rapid Deposition Technology Holds the Key for the World's Largest Manufacturer of Thin-Film Solar Modules (Fact Sheet)

    SciTech Connect

    Not Available

    2013-08-01

    First Solar, Inc. has been collaborating with NREL since 1991, advancing its thin-film cadmium telluride solar technology to grow from a startup company to become one of the world's largest manufacturers of solar modules, and the world's largest manufacturer of thin-film solar modules.

  9. Fabrication of contact holes by rear side laser ablation of polyimide foils for CIGS solar modules

    NASA Astrophysics Data System (ADS)

    Ehrhardt, Martin; Scheit, Christian; Ragnow, Steffen; Lorenz, Pierre; Wehrmann, Anja; Braun, Alexander; Zimmer, Klaus

    2013-08-01

    Laser technology is of increasing interest for the improvement of photovoltaic generators also for mass production. Copper-indium-gallium-diselenide (CIGS) thin film solar cells on flexible polyimide (PI) foil have great potential for specific applications requiring mechanical flexibility. To reduce the dead area of solar modules especially that of the serial interconnection shingling of the solar cells is one encouraging approach. The former developed back side opening process is utilized for via preparation to realize the serial interconnection at the rear side of the solar cells. Arrays of square vias that were fabricated into the polyimide foil by UV laser ablation were filled with a silver-based conductive adhesive for realizing the electrical and mechanical interconnection. Contact resistance of the silver-based adhesive to the solar cell back contact of less than 0.2 Ω mm2 has been measured. Shingled CIGS modules with a size of 100 cm2 having an open circuit voltage of 2.3 V and a short circuit current of more than 500 mA demonstrate the great potential of this interconnection approach for flexible electronic applications.

  10. Carrier lifetimes in thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  11. Study and Optimization of Metal Nanoparticles for the Enhanced Efficiency Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Shilpa, G. D.; Subramanyam, T. K.; Sreelakshmi, K.; Uttarakumari

    2016-09-01

    Thin film silicon solar cells have the potential to considerably decrease the cost of photovoltaic. To increase the conversion efficiency of thin film solar cells, nano-sized structures, such as nanoparticle deposition at the front end, were proposed. In the present study, spherical metal nanoparticles such as gold (Au) and silver (Ag) were deployed at the front of the silicon solar cell. The effect of metal nanoparticles on the absorption enhancement factor of the thin film solar cells was investigated using Lumerical Finite Difference Time Domain (FDTD) solutions. Also the influence of geometrical parameters of spherical nanoparticles on absorption enhancement factor was examined. The maximum absorption enhancement factor was achieved by optimizing the geometrical parameters of nanoparticles. The structure with Ag nanoparticles at the front end of the silicon solar cell exhibits higher absorption enhancement factor than the structure with Au nanoparticles.

  12. A comprehensive study for the plasmonic thin-film solar cell with periodic structure.

    PubMed

    Sha, Wei E I; Choy, Wallace C H; Chew, Weng Cho

    2010-03-15

    A comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary condition and the one-sided difference scheme are adopted. The parameter extraction methods for the zeroth-order reflectance and the absorbed power density are also discussed, which is important for testing and optimizing the solar cell design. For the numerical results, the physics of the absorption peaks of the amorphous silicon thin-film solar cell are explained by electromagnetic theory; these peaks correspond to the waveguide mode, Floquet mode, surface plasmon resonance, and the constructively interference between adjacent metal strips. The work is therefore important for the theoretical study and optimized design of the plasmonic thin-film solar cell.

  13. Applications of thin film technology toward a low-mass solar power satellite

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Cull, Ronald C.

    1990-01-01

    Previous concepts for solar power satellites have used conventional-technology photovoltaics and microwave tubes. The authors propose using thin film photovoltaics and an integrated solid state phased array to design an ultra-lightweight solar power satellite, resulting in a potential reduction in weight by a factor of ten to a hundred over conventional concepts for solar power satellites.

  14. Role of surface recombination in affecting the efficiency of nanostructured thin-film solar cells.

    PubMed

    Da, Yun; Xuan, Yimin

    2013-11-04

    Nanostructured light trapping is a promising way to improve the efficiency in thin-film solar cells recently. In this work, both the optical and electrical properties of thin-film solar cells with 1D periodic grating structure are investigated by using photoelectric coupling model. It is found that surface recombination plays a key role in determining the performance of nanostructured thin-film solar cells. Once the recombination effect is considered, the higher optical absorption does not mean the higher conversion efficiency as most existing publications claimed. Both the surface recombination velocity and geometric parameters of structure have great impact on the efficiency of thin-film solar cells. Our simulation results indicate that nanostructured light trapping will not only improve optical absorption but also boost the surface recombination simultaneously. Therefore, we must get the tradeoffs between optical absorption and surface recombination to obtain the maximum conversion efficiency. Our work makes it clear that both the optical absorption and electrical recombination response should be taken into account simultaneously in designing the nanostructured thin-film solar cells.

  15. Analyzing periodic and random textured silicon thin film solar cells by Rigorous Coupled Wave Analysis

    PubMed Central

    Dewan, Rahul; Jovanov, Vladislav; Hamraz, Saeed; Knipp, Dietmar

    2014-01-01

    A simple and fast method was developed to determine the quantum efficiency and short circuit current of thin-film silicon solar cells prepared on periodically or randomly textured surfaces. The optics was studied for microcrystalline thin-film silicon solar cells with integrated periodic and random surface textures. Rigorous Coupled Wave Analysis (RCWA) was used to investigate the behaviour of the solar cells. The analysis of the periodic and random textured substrates allows for deriving optimal surface textures. Furthermore, light trapping in periodic and randomly textured substrates will be compared. PMID:25112301

  16. Optimization of CdS Buffer Layer for High Efficiency CIGS Solar Cells.

    PubMed

    Kim, Donguk; Jang, Yong-Jun; Jung, Ho-Sung; Kim, Minha; Baek, Dohyun; Yi, Junsin; Lee, Jaehyeong; Choi, Youngkwan

    2016-05-01

    In present work, effects of the thickness on the structural and optical properties of chemically deposited CdS thin films were investigated. In addition, we fabricated Cu(In, Ga)Se2 solar cells with various thicknesses of CdS buffer layer and optimized the thickness for a high efficiency. When the CdS thin films were thicker, the crystallinity improved but the transmittance decreased. The short-circuit current density (J(sc)) and the fill factor are the major efficiency limiting factors for the CIGS solar cells. As the thickness of the CdS buffer layer, the open-circuit voltage (V(oc)) and the fill factor increased, whereas the J(sc) slightly decreased. The improvement of the fill factor and thus efficiency resulted from larger shunt resistance. For the solar cells without a high resistive intrinsic ZnO layer, the highest efficiency was acquired at the thickness of 89 nm. With further increasing the thickness, the J(sc) decreased significantly, resulting in poor efficiency.

  17. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    PubMed

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk.

  18. Effects of Cd-free buffer layer for CuInSe{sub 2} thin-film solar cells

    SciTech Connect

    Nii, T.; Sugiyama, I.; Kase, T.; Sato, M.; Kaniyama, Y.; Kuriyagawa, S.; Kushiya, K.; Takeshita, H.

    1994-12-31

    ZnO buffer layer by a chemical-bath deposition (CBD) method is developed in this study to improve the interface quality between n-ZnO window layer and p-CuInSe{sub 2} (CIS) thin-film absorber in CIS thin-film solar cells as one of the approaches to the fabrication of Cd-free thin-film solar cells. The optimization of the fabrication conditions of CBD-ZnO leads to the efficiency of about 10%. These results indicate the CBD-ZnO buffer layer has rather high capability to fabricate high-efficiency CIS thin-film solar cells.

  19. Broadband Absorption Enhancement in Thin Film Solar Cells Using Asymmetric Double-Sided Pyramid Gratings

    NASA Astrophysics Data System (ADS)

    Alshal, Mohamed A.; Allam, Nageh K.

    2016-11-01

    A design for a highly efficient modified grating crystalline silicon (c-Si) thin film solar cell is demonstrated and analyzed using the two-dimensional (2-D) finite element method. The suggested grating has a double-sided pyramidal structure. The incorporation of the modified grating in a c-Si thin film solar cell offers a promising route to harvest light into the few micrometers active layer. Furthermore, a layer of silicon nitride is used as an antireflection coating (ARC). Additionally, the light trapping through the suggested design is significantly enhanced by the asymmetry of the top and bottom pyramids. The effects of the thickness of the active layer and facet angle of the pyramid on the spectral absorption, ultimate efficiency ( η), and short-circuit current density ( J sc) are investigated. The numerical results showed 87.9% efficiency improvement over the conventional thin film c-Si solar cell counterpart without gratings.

  20. Two-terminal, thin film, tandem solar cells

    SciTech Connect

    Stanbery, B.J.

    1987-07-14

    This patent describes a polycrystalline, tandem, photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising a heterojunction of n-type CdSe and p-type ZnTe, the junction being formed by depositing the ZnTe on the CdSe at low temperatures below about 350/sup 0/C; (b) a lower cell electrically connected to the upper cell, having a bandgap of about 1.0 eV, and comprising a thin film heterojunction between a graded ternary I-III-VI/sub 2/ semiconductor and a thin film II-VI semiconductor window layer.

  1. Properties of Cd and Zn Partial Electrolyte Treated CIGS Solar Cells: Preprint

    SciTech Connect

    Ramanathan, K.; Hasoon, F. S.; Smith, S.; Mascarenhas, A.; Al-Thani, H.; Alleman, J.; Ullal, H. S.; Keane, J.; Johnson, P. K.; Sites, J. R.

    2002-05-01

    We study the influence of Cd partial baths on the photovoltaic properties of CuInGaSe2 (CIGS) and CuIn-GaSSe2 (CIGSS) thin film absorbers. We find that efficient solar cells can be fabricated by this treatment, and we compare their properties with those containing CdS window layers grown by chemical bath deposition. The results suggest that Cd plays a dominant role in establishing efficient photovoltaic junctions in CuInSe2 alloys. Micron scale photoluminescence scans show non-uniformity along the length probed. Cd treatment quenches one of the luminescence transitions, which indicates a change in shallow acceptor level density. We present a model that helps to explain the evolution of photovoltaic action.

  2. Electrodeposition of ZnO-doped films as window layer for Cd-free CIGS-based solar cells

    NASA Astrophysics Data System (ADS)

    Tsin, Fabien; Vénérosy, Amélie; Hildebrandt, Thibaud; Hariskos, Dimitrios; Naghavi, Negar; Lincot, Daniel; Rousset, Jean

    2016-02-01

    The Cu(In,Ga)Se2 (CIGS) thin film solar cell technology has made a steady progress within the last decade reaching efficiency up to 22.3% on laboratory scale, thus overpassing the highest efficiency for polycrystalline silicon solar cells. High efficiency CIGS modules employ a so-called buffer layer of cadmium sulfide CdS deposited by Chemical Bath Deposition (CBD), which presence and Cd-containing waste present some environmental concerns. A second potential bottleneck for CIGS technology is its window layer made of i-ZnO/ZnO:Al, which is deposited by sputtering requiring expensive vacuum equipment. A non-vacuum deposition of transparent conductive oxide (TCO) relying on simpler equipment with lower investment costs will be more economically attractive, and could increase competitiveness of CIGS-based modules with the mainstream silicon-based technologies. In the frame of Novazolar project, we have developed a low-cost aqueous solution photo assisted electrodeposition process of the ZnO-based window layer for high efficiency CIGS-based solar cells. The window layer deposition have been first optimized on classical CdS buffer layer leading to cells with efficiencies similar to those measured with the sputtered references on the same absorber (15%). The the optimized ZnO doped layer has been adapted to cadmium free devices where the CdS is replaced by chemical bath deposited zinc oxysulfide Zn(S,O) buffer layer. The effect of different growth parameters has been studied on CBD-Zn(S,O)-plated co-evaporated Cu(In,Ga)Se2 substrates provided by the Zentrum für Sonnenenergie-und Wasserstoff-Forschung (ZSW). This optimization of the electrodeposition of ZnO:Cl on CIGS/Zn(S,O) stacks led to record efficiency of 14%, while the reference cell with a sputtered (Zn,Mg)O/ZnO:Al window layer has an efficiency of 15.2%.

  3. Optical Metrology for CIGS Solar Cell Manufacturing and its Cost Implications

    NASA Astrophysics Data System (ADS)

    Sunkoju, Sravan Kumar

    Solar energy is a promising source of renewable energy which can meet the demand for clean energy in near future with advances in research in the field of photovoltaics and cost reduction by commercialization. Availability of a non-contact, in-line, real time robust process control strategies can greatly aid in reducing the gap between cell and module efficiencies, thereby leading to cost-effective large-scale manufacturing of high efficiency CIGS solar cells. In order to achieve proper process monitoring and control for the deposition of the functional layers of CuIn1-xGaxSe 2 (CIGS) based thin film solar cell, optical techniques such as spectroscopic reflectometry and polarimetry are advantageous because they can be set up in an unobtrusive manner in the manufacturing line, and collect data in-line and in-situ. The use of these techniques requires accurate optical models that correctly represent the properties of the layers being deposited. In this study, Spectroscopic ellipsometry (SE) has been applied for the characterization of each individual stage of CIGS layers deposited using the 3-stage co-evaporation process along with the other functional layers. Dielectric functions have been determined for the energy range from 0.7 eV to 5.1 eV. Critical-point line-shape analysis was used in this study to determine the critical point energies of the CIGS based layers. To control the compositional and thickness uniformity of all the functional layers during the fabrication of CIGS solar cells over large areas, multilayer photovoltaics (PV) stack optical models were developed with the help of extracted dielectric functions. In this study, mapping capability of RC2 spectroscopic ellipsometer was used to map all the functional layer thicknesses of a CIGS solar cell in order to probe the spatial non-uniformities that can affect the performance of a cell. The optical functions for each of the stages of CIGS 3-stage deposition process along with buffer layer and transparent

  4. The potential and device physics of interdigitated thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Metzger, Wyatt K.

    2008-05-01

    The device physics of thin-film solar cells with interdigitated p-n junctions is examined for a range of spatial sizes, band offsets, and material parameters. The results are illustrated by focusing on recent nanoscale concepts for Cu(In,Ga)Se2 solar cells. Ideally, nanoscale interdigitated junctions can improve solar cell performance relative to planar-junction devices, and make reasonably high solar cell efficiencies (>15%) attainable even with mediocre electro-optical materials.

  5. Absorption efficiency enhancement in inorganic and organic thin film solar cells via plasmonic honeycomb nanoantenna arrays.

    PubMed

    Tok, Rüştü Umut; Sendur, Kürşat

    2013-08-15

    We demonstrate theoretically that by embedding plasmonic honeycomb nanoantenna arrays into the active layers of inorganic (c-Si) and organic (P3HT:PCBM/PEDOT:PSS) thin film solar cells, absorption efficiency can be improved. To obtain the solar cell absorption spectrum that conforms to the solar radiation, spectral broadening is achieved by breaking the symmetry within the Wigner-Seitz unit cell on a uniform hexagonal grid. For optimized honeycomb designs, absorption efficiency enhancements of 106.2% and 20.8% are achieved for c-Si and P3HT:PCBM/PEDOT:PSS thin film solar cells, respectively. We have demonstrated that the transverse modes are responsible for the enhancement in c-Si solar cells, whereas both the longitudinal and transverse modes, albeit weaker, are the main enhancement mechanisms for P3HT:PCBM/PEDOT:PSS solar cells. For both inorganic and organic solar cells, the absorption enhancement is independent of polarization.

  6. Optoelectronic characterization of wide-bandgap (AgCu)(InGa)Se 2 thin-film polycrystalline solar cells including the role of the intrinsic zinc oxide layer

    NASA Astrophysics Data System (ADS)

    Obahiagbon, Uwadiae

    Experiments and simulations were conducted to vary the thickness and the sheet resistance of the high resistance (HR) ZnO layer in polycrystalline thin film (AgCu)(GaIn)Se2 (ACIGS) solar cells. The effect of varying these parameters on the electric field distribution, depletion width and hence capacitance were studied by SCAPS simulation. Devices were then fabricated and characterized by a number of optoelectronic techniques. Thin film CIGS has received a lot of attention, for its use as an absorber layer for thin film solar cells. However, the addition of Silver (Ag) to the CIGS alloy system increases the band gap as indicated from optical transmission measurements and thus higher open circuit voltage (Voc) could be obtained. Furthermore, addition of Ag lowers the melting temperature of the alloy and it is expected that this lowers the defect densities in the absorber and thus leads to higher performance. Transient photocapacitance analysis on ACIGS devices shows sharper band edge indicating lower disorder than CIGS. Presently there is a lack of fundamental knowledge relating film characteristics to device properties and performance. This is due to the fact that some features in the present solar cell structure have been optimized empirically. The goal of this research effort was to develop a fundamental and detailed understanding of the device operation as well as the loss mechanism(s) limiting these devices. Recombination mechanisms in finished ACIGS solar cell devices was studied using advanced admittance techniques (AS, DLCP, CV) to identify electronically active defect state(s) and to study their impact on electronic properties and device performance. Analysis of various optoelectronic measurements of ACIGS solar cells provided useful feedback regarding the impact on device performance of the HR ZnO layer. It was found that thickness between 10-100 nm had negligible impact on performance but reducing the thickness to 0 nm resulted in huge variability in all

  7. Advances in thin-film solar cells for lightweight space photovoltaic power

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Bailey, Sheila G.; Flood, Dennis J.

    1989-01-01

    The development of photovoltaic arrays beyond the next generation is discussed with attention given to the potentials of thin-film polycrystalline and amorphous cells. Of particular importance is the efficiency (the fraction of incident solar energy converted to electricity) and specific power (power to weight ratio). It is found that the radiation tolerance of thin-film materials is far greater than that of single crystal materials. CuInSe2 shows no degradation when exposed to 1-MeV electrons.

  8. Improved Transparent Conducting Oxides Boost Performance of Thin-Film Solar Cells (Fact Sheet)

    SciTech Connect

    Not Available

    2011-02-01

    Today?s thin-film solar cells could not function without transparent conducting oxides (TCOs). TCOs act as a window, both protecting the cell and allowing light to pass through to the cell?s active layers. Until recently, TCOs were seen as a necessary, but static, layer of a thin-film photovoltaic (PV) cell. But a group of researchers at the National Renewable Energy Laboratory (NREL) has identified a pathway to producing improved TCO films that demonstrate higher infrared transparency. To do so, they have modified the TCOs in ways that did not seem possible a few years ago.

  9. Optical and structural properties of sputtered CdS films for thin film solar cell applications

    SciTech Connect

    Kim, Donguk; Park, Young; Kim, Minha; Choi, Youngkwan; Park, Yong Seob; Lee, Jaehyoeng

    2015-09-15

    Graphical abstract: Photo current–voltage curves (a) and the quantum efficiency (QE) (b) for the solar cell with CdS film grown at 300 °C. - Highlights: • CdS thin films were grown by a RF magnetron sputtering method. • Influence of growth temperature on the properties of CdS films was investigated. • At higher T{sub g}, the crystallinity of the films improved and the grains enlarged. • CdS/CdTe solar cells with efficiencies of 9.41% were prepared at 300 °C. - Abstract: CdS thin films were prepared by radio frequency magnetron sputtering at various temperatures. The effects of growth temperature on crystallinity, surface morphology and optical properties of the films were characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectra, UV–visible spectrophotometry, and photoluminescence (PL) spectra. As the growth temperature was increased, the crystallinity of the sputtered CdS films was improved and the grains were enlarged. The characteristics of CdS/CdTe thin film solar cell appeared to be significantly influenced by the growth temperature of the CdS films. Thin film CdS/CdTe solar cells with efficiencies of 9.41% were prepared at a growth temperature of 300 °C.

  10. Method of forming particulate materials for thin-film solar cells

    DOEpatents

    Eberspacher, Chris; Pauls, Karen Lea

    2004-11-23

    A method for preparing particulate materials useful in fabricating thin-film solar cells is disclosed. Particulate materials is prepared by the method include for example materials comprising copper and indium and/or gallium in the form of single-phase, mixed-metal oxide particulates; multi-phase, mixed-metal particulates comprising a metal oxide; and multinary metal particulates.

  11. Dielectric Scattering Patterns for Efficient Light Trapping in Thin-Film Solar Cells.

    PubMed

    van Lare, Claire; Lenzmann, Frank; Verschuuren, Marc A; Polman, Albert

    2015-08-12

    We demonstrate an effective light trapping geometry for thin-film solar cells that is composed of dielectric light scattering nanocavities at the interface between the metal back contact and the semiconductor absorber layer. The geometry is based on resonant Mie scattering. It avoids the Ohmic losses found in metallic (plasmonic) nanopatterns, and the dielectric scatterers are well compatible with nearly all types of thin-film solar cells, including cells produced using high temperature processes. The external quantum efficiency of thin-film a-Si:H solar cells grown on top of a nanopatterned Al-doped ZnO, made using soft imprint lithography, is strongly enhanced in the 550-800 nm spectral band by the dielectric nanoscatterers. Numerical simulations are in good agreement with experimental data and show that resonant light scattering from both the AZO nanostructures and the embedded Si nanostructures are important. The results are generic and can be applied on nearly all thin-film solar cells.

  12. Disorder improves nanophotonic light trapping in thin-film solar cells

    SciTech Connect

    Paetzold, U. W. Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Carius, R.; Rau, U.; Michaelis, D.; Waechter, C.

    2014-03-31

    We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500 nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500 nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures.

  13. Effects of simulated solar radiation on the transmission of magnesium fluoride and cryolite thin films

    NASA Technical Reports Server (NTRS)

    Heslin, T.

    1974-01-01

    Thin films of cryolite magnesium fluoride on fused silica substrates were exposed to 1126 equivalent sun-hours of radiation. The optical transmissions of the samples were measured before and after irradiation. The results indicate that, after the degradation of the silica substrate is accounted for, the cryolite is severely affected by the simulated solar radiation, but the magnesium fluoride is only slightly affected.

  14. Disorder improves nanophotonic light trapping in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Paetzold, U. W.; Smeets, M.; Meier, M.; Bittkau, K.; Merdzhanova, T.; Smirnov, V.; Michaelis, D.; Waechter, C.; Carius, R.; Rau, U.

    2014-03-01

    We present a systematic experimental study on the impact of disorder in advanced nanophotonic light-trapping concepts of thin-film solar cells. Thin-film solar cells made of hydrogenated amorphous silicon were prepared on imprint-textured glass superstrates. For periodically textured superstrates of periods below 500 nm, the nanophotonic light-trapping effect is already superior to state-of-the-art randomly textured front contacts. The nanophotonic light-trapping effect can be associated to light coupling to leaky waveguide modes causing resonances in the external quantum efficiency of only a few nanometer widths for wavelengths longer than 500 nm. With increasing disorder of the nanotextured front contact, these resonances broaden and their relative altitude decreases. Moreover, overall the external quantum efficiency, i.e., the light-trapping effect, increases incrementally with increasing disorder. Thereby, our study is a systematic experimental proof that disorder is conceptually an advantage for nanophotonic light-trapping concepts employing grating couplers in thin-film solar cells. The result is relevant for the large field of research on nanophotonic light trapping in thin-film solar cells which currently investigates and prototypes a number of new concepts including disordered periodic and quasi periodic textures.

  15. Research on polycrystalline thin-film CuInGaSe{sub 2} solar cells. Annual subcontract report, 3 May 1991--21 May 1993

    SciTech Connect

    Chen, W.S.; Stewart, J.M.; Mickelsen, R.A.; Devaney, W.E.; Stanbery, B.J.

    1993-10-01

    This report describes work to fabricate high-efficiency CdZnS/CuInGaSe{sub 2}, thin-film solar cells and to develop improved transparent conductor window layers such as ZnO. The specific technical milestone for Phase I was to demonstrate an air mass (AM) 1.5 global 13% , 1-cm{sup 2} total-area CuInGaSe{sub 2} (CIGS) thin-film solar cell. For Phase II, the objective was to demonstrate an AM1.5 global 13.5%, 1-cm{sup 2} total-area efficiency. We focused our activities on three areas. First, we modified the CIGS deposition system to double its substrate capacity. Second, we developed new tooling to enable investigation of a modified aqueous CdZnS process in which the goal was to improve the yield of this critical step in the device fabrication process. Third, we upgraded the ZnO sputtering system to improve its reliability and reproducibility. A dual rotatable cathode metallic source was installed, and the sputtering parameters were further optimized to improve ZnO`s properties as a transparent conducting oxide (TCO). Combining the refined CdZnS process with CIGS from the newly fixtured deposition system enable us to fabricate and deliver a ZnO/Cd{sub 0.08}Zn{sub 0.20}S/CuIn{sub 0.74}Ga{sub 0.26}Se{sub 2} cell on alumina with I-V characteristics, as measured by NREL under standard test conditions, of 13.7% efficiency with V{proportional_to} = 0.5458 V, J{sub sc} = 35.48 mA/cm{sup 2}, FF = 0.688, and efficiency = 14.6%.

  16. Fabrication of organic-inorganic perovskite thin films for planar solar cells via pulsed laser deposition

    SciTech Connect

    Liang, Yangang; Zhang, Xiaohang; Gong, Yunhui; Shin, Jongmoon; Wachsman, Eric D.; Takeuchi, Ichiro; Yao, Yangyi; Hsu, Wei-Lun; Dagenais, Mario

    2016-01-15

    We report on fabrication of organic-inorganic perovskite thin films using a hybrid method consisting of pulsed laser deposition (PLD) of lead iodide and spin-coating of methylammonium iodide. Smooth and highly crystalline CH{sub 3}NH{sub 3}PbI{sub 3} thin films have been fabricated on silicon and glass coated substrates with fluorine doped tin oxide using this PLD-based hybrid method. Planar perovskite solar cells with an inverted structure have been successfully fabricated using the perovskite films. Because of its versatility, the PLD-based hybrid fabrication method not only provides an easy and precise control of the thickness of the perovskite thin films, but also offers a straightforward platform for studying the potential feasibility in using other metal halides and organic salts for formation of the organic-inorganic perovskite structure.

  17. Plasmonic effects in amorphous silicon thin film solar cells with metal back contacts.

    PubMed

    Palanchoke, Ujwol; Jovanov, Vladislav; Kurz, Henning; Obermeyer, Philipp; Stiebig, Helmut; Knipp, Dietmar

    2012-03-12

    Plasmonic effects in amorphous silicon thin film solar cells with randomly textured metal back contact were investigated experimentally and numerically. The influence of different metal back contacts with and without ZnO interlayer was studied and losses in the individual layers of the solar cell were quantified. The amorphous silicon thin film solar cells were prepared on randomly textured substrates using large area production equipment and exhibit conversion efficiencies approaching 10%. The optical wave propagation within the solar cells was studied by Finite Difference Time Domain simulations. The quantum efficiency of solar cells with and without ZnO interlayer was simulated and the interplay between the reflection, quantum efficiency and absorption in the back contact will be discussed.

  18. Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

    DOEpatents

    Wang, Qi; Iwaniczko, Eugene

    2006-10-17

    A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

  19. Surface Engineering of ZnO Thin Film for High Efficiency Planar Perovskite Solar Cells

    PubMed Central

    Tseng, Zong-Liang; Chiang, Chien-Hung; Wu, Chun-Guey

    2015-01-01

    Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties. PMID:26411577

  20. Thermally evaporated methylammonium tin triiodide thin films for lead-free perovskite solar cell fabrication

    SciTech Connect

    Yu, Yue; Zhao, Dewei; Grice, Corey R.; Meng, Weiwei; Wang, Changlei; Liao, Weiqiang; Cimaroli, Alexander J.; Zhang, Hongmei; Zhu, Kai; Yan, Yanfa

    2016-01-01

    We report on the synthesis of methylammonium tin triiodide (MASnI3) thin films at room temperature by a hybrid thermal evaporation method and their application in fabricating lead (Pb)-free perovskite solar cells. The as-deposited MASnI3 thin films exhibit smooth surfaces, uniform coverage across the entire substrate, and strong crystallographic preferred orientation along the <100> direction. By incorporating this film with an inverted planar device architecture, our Pb-free perovskite solar cells are able to achieve an open-circuit voltage (Voc) up to 494 mV. The relatively high Voc is mainly ascribed to the excellent surface coverage, the compact morphology, the good stoichiometry control of the MASnI3 thin films, and the effective passivation of the electron-blocking and hole-blocking layers. Our results demonstrate the potential capability of the hybrid evaporation method to prepare high-quality Pb-free MASnI3 perovskite thin films which can be used to fabricate efficient Pb-free perovskite solar cells.

  1. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

    SciTech Connect

    Chu, T.L. )

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

  2. Angular dependence of light trapping in nanophotonic thin-film solar cells.

    PubMed

    Smeets, Michael; Smirnov, Vladimir; Bittkau, Karsten; Meier, Matthias; Carius, Reinhard; Rau, Uwe; Paetzold, Ulrich W

    2015-11-30

    The angular dependence of light-trapping in nanophotonic thin-film solar cells is inherent due to the wavelength-scale dimensions of the periodic nanopatterns. In this paper, we experimentally investigate the dependence of light coupling to waveguide modes for light trapping in a-Si:H solar cells deposited on nanopatterned back contacts. First, we accurately determine the spectral positions of individual waveguide modes in thin-film solar cells in external quantum efficiency and absorptance. Second, we demonstrate the strong angular dependence of this spectral position for our solar cells. Third, a moderate level of disorder is introduced to the initially periodic nanopattern of the back contacts. As a result, the angular dependence is reduced. Last, we experimentally compare this dependence on the angle of incidence for randomly textured, 2D periodically nanopatterned and 2D disordered back contacts in external quantum efficiency and short-circuit current density.

  3. Real time intelligent process control system for thin film solar cell manufacturing

    SciTech Connect

    George Atanasoff

    2010-10-29

    This project addresses the problem of lower solar conversion efficiency and waste in the typical solar cell manufacturing process. The work from the proposed development will lead toward developing a system which should be able to increase solar panel conversion efficiency by an additional 12-15% resulting in lower cost panels, increased solar technology adoption, reduced carbon emissions and reduced dependency on foreign oil. All solar cell manufacturing processes today suffer from manufacturing inefficiencies that currently lead to lower product quality and lower conversion efficiency, increased product cost and greater material and energy consumption. This results in slower solar energy adoption and extends the time solar cells will reach grid parity with traditional energy sources. The thin film solar panel manufacturers struggle on a daily basis with the problem of thin film thickness non-uniformity and other parameters variances over the deposited substrates, which significantly degrade their manufacturing yield and quality. Optical monitoring of the thin films during the process of the film deposition is widely perceived as a necessary step towards resolving the non-uniformity and non-homogeneity problem. In order to enable the development of an optical control system for solar cell manufacturing, a new type of low cost optical sensor is needed, able to acquire local information about the panel under deposition and measure its local characteristics, including the light scattering in very close proximity to the surface of the film. This information cannot be obtained by monitoring from outside the deposition chamber (as traditional monitoring systems do) due to the significant signal attenuation and loss of its scattering component before the reflected beam reaches the detector. In addition, it would be too costly to install traditional external in-situ monitoring systems to perform any real-time monitoring over large solar panels, since it would require

  4. Thin film solar cells. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1997-11-01

    The bibliography contains citations concerning research and development of high-efficiency and low-cost thin film solar cells. References discuss the design and fabrication of silicon, gallium arsenide, copper selenide, indium selenide, cadmium telluride, and copper indium selenide solar cells. Applications in space and utilities are examined. Government projects and foreign technology are also reviewed. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  5. Processing and modeling issues for thin-film solar cell devices. Final report

    SciTech Connect

    Birkmire, R.W.; Phillips, J.E.

    1997-11-01

    During the third phase of the subcontract, IEC researchers have continued to provide the thin film PV community with greater depth of understanding and insight into a wide variety of issues including: the deposition and characterization of CuIn{sub 1-x}Ga{sub x}Se{sub 2}, a-Si, CdTe, CdS, and TCO thin films; the relationships between film and device properties; and the processing and analysis of thin film PV devices. This has been achieved through the systematic investigation of all aspects of film and device production and through the analysis and quantification of the reaction chemistries involved in thin film deposition. This methodology has led to controlled fabrications of 15% efficient CuIn{sub 1-x}Ga{sub x}Se{sub 2} solar cells over a wide range of Ga compositions, improved process control of the fabrication of 10% efficient a-Si solar cells, and reliable and generally applicable procedures for both contacting and doping films. Additional accomplishments are listed below.

  6. Growth mechanism of Ge-doped CZTSSe thin film by sputtering method and solar cells.

    PubMed

    Li, Jinze; Shen, Honglie; Chen, Jieyi; Li, Yufang; Yang, Jiale

    2016-10-19

    Ge-doped CZTSSe thin films were obtained by covering a thin Ge layer on CZTS precursors, followed by a selenization process. The effect of the Ge layer thickness on the morphologies and structural properties of Ge-doped CZTSSe thin films were studied. It was found that Ge doping could promote grain growth to form a compact thin film. The lattice shrank in the top-half of the film due to the smaller atomic radius of Ge, leading to the formation of tensile stress. According to thermodynamic analysis, Sn was easier to be selenized than Ge. Thus, Ge preferred to remain on the surface and increased the surface roughness when the Ge layer was thin. CZTSe was easier to form than Ge-doped CZTSe, which caused difficulty in Ge doping. These results offered a theoretical and experimental guide for preparing Ge-doped CZTSSe thin films for the potential applications in low-cost solar cells. With a 10 nm Ge layer on the top of the precursor, the conversion efficiency of the solar cell improved to 5.38% with an open-circuit voltage of 403 mV, a short-circuit current density of 28.51 mA cm(-2) and a fill factor of 46.83% after Ge doping.

  7. Light trapping in thin-film silicon solar cells with photonic structures

    NASA Astrophysics Data System (ADS)

    Andreani, Lucio C.; Bozzola, Angelo; Kowalczewski, Piotr; Liscidini, Marco

    2013-05-01

    Efficient photovoltaic conversion of solar energy requires optimization of both light absorption and carrier collection. This manuscript reviews theoretical studies of thin-film silicon solar cells with various kinds of ordered and disordered photonic structures. Light trapping capabilities of these systems are analyzed by means of rigorous coupled-wave analysis and compared with the so-called Lambertian limit as given by a fully randomizing light scatterer. The best photonic structures are found to require proper combinations of order and disorder, and can be fabricated starting from pre-patterned rough substrates. Carrier collection is studied by means of analytic models and by full electro-optical simulations. The results indicate that thin-film silicon solar cells can outperform bulk ones with comparable material quality, provided surface recombination is kept below a critical level, which is compatible with present-day surface passivation technologies.

  8. Thin-film solar cell fabricated on a flexible metallic substrate

    DOEpatents

    Tuttle, John R.; Noufi, Rommel; Hasoon, Falah S.

    2006-05-30

    A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

  9. Transfer printing methods for flexible thin film solar cells: basic concepts and working principles.

    PubMed

    Lee, Chi Hwan; Kim, Dong Rip; Zheng, Xiaolin

    2014-09-23

    Fabricating thin film solar cells (TFSCs) on flexible substrates will not only broaden the applications of solar cells, but also potentially reduce the installation cost. However, a critical challenge for fabricating flexible TFSCs on flexible substrates is the incompatibility issues between the thermal, mechanical, and chemical properties of these substrates and the fabrication conditions. Transfer printing methods, which use conventional substrates for the fabrication and then deliver the TFSCs onto flexible substrates, play a key role to overcome these challenges. In this review, we discuss the basic concepts and working principles of four major transfer printing methods associated with (1) transfer by sacrificial layers, (2) transfer by porous Si layer, (3) transfer by controlled crack, and (4) transfer by water-assisted thin film delamination. We also discuss the challenges and opportunities for implementing these methods for practical solar cell manufacture.

  10. Recent advances in the transparent conducting ZnO for thin-film Si solar cells

    NASA Astrophysics Data System (ADS)

    Moon, Taeho; Shin, Gwang Su; Park, Byungwoo

    2015-11-01

    The key challenge for solar-cell development lies in the improvement of power-conversion efficiency and the reduction of fabrication cost. For thin-film Si solar cells, researches have been especially focused on the light trapping for the breakthrough in the saturated efficiencies. The ZnO-based transparent conducting oxides (TCOs) have therefore received strong attention because of their excellent light-scattering capability by the texture-etched surface and cost effectiveness through in-house fabrication. Here, we have highlighted our recent studies on the transparent conducting ZnO for thin-film Si solar cells. From the electrical properties and their degradation mechanisms, bilayer deposition and organic-acid texturing approaches for enhancing the light trapping, and finally the relation between textured ZnO and electrical cell performances are sequentially introduced in this review article. [Figure not available: see fulltext.

  11. Thin-Film Solar Cell Fabricated on a Flexible Metallic Substrate

    DOEpatents

    Tuttle, J. R.; Noufi, R.; Hasoon, F. S.

    2006-05-30

    A thin-film solar cell (10) is provided. The thin-film solar cell (10) comprises a flexible metallic substrate (12) having a first surface and a second surface. A back metal contact layer (16) is deposited on the first surface of the flexible metallic substrate (12). A semiconductor absorber layer (14) is deposited on the back metal contact. A photoactive film deposited on the semiconductor absorber layer (14) forms a heterojunction structure and a grid contact (24) deposited on the heterjunction structure. The flexible metal substrate (12) can be constructed of either aluminium or stainless steel. Furthermore, a method of constructing a solar cell is provided. The method comprises providing an aluminum substrate (12), depositing a semiconductor absorber layer (14) on the aluminum substrate (12), and insulating the aluminum substrate (12) from the semiconductor absorber layer (14) to inhibit reaction between the aluminum substrate (12) and the semiconductor absorber layer (14).

  12. Buffer layer optimization for high efficiency CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Severino, N.; Bednar, N.; Adamovic, N.

    2016-10-01

    This work presents a study concerning the numerical optimization of a buffer layer for high efficiency CIGS solar cells. The dependence of the solar cell properties on the buffer layer material, the layer thickness, the type and density of defects within the same layer were numerically investigated and analysed. Promising results were obtained with alternative Cd-free buffer layers (ZnSnO, InS and ZnS) in place of the standard CdS.

  13. Space Plasma Testing of High-Voltage Thin-Film Solar Arrays with Protective Coatings

    NASA Technical Reports Server (NTRS)

    Tlomak, Pawel; Hausgen, Paul E.; Merrill, John; Senft, Donna; Piszczor, Michael F., Jr.

    2007-01-01

    This paper gives an overview of the space plasma test program for thin-film photovoltaics (TFPV) technologies developed at the Air Force Research Laboratory (AFRL). The main objective of this program is to simulate the effects of space plasma characteristic of LEO and MEO environments on TFPV. Two types of TFPV, amorphous silicon (a-Si) and copper-indium-gallium-diselenide (CIGS), coated with two types of thin-film, multifunctional coatings were used for these studies. This paper reports the results of the first phase of this program, namely the results of preliminary electrostatic charging, arcing, dielectric breakdown, and collection current measurements carried out with a series of TFPV exposed to simulated space plasma at the NASA Glenn Plasma Interaction Facility. The experimental data demonstrate that multifunctional coatings developed for this program provide effective protection against the plasma environment while minimizing impact on power generation performance. This effort is part of an ongoing program led by the Space Vehicles Directorate at the AFRL devoted to the development and space qualification of TFPV and their protective coatings.

  14. Light-trapping design of graphene transparent electrodes for efficient thin-film silicon solar cells.

    PubMed

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2012-09-01

    In this paper, the performance of solar cells with graphene transparent electrodes is compared with cells using conventional indium tin oxide (ITO) electrodes, and it is demonstrated the optical absorption of solar cells with bare graphene structure is worse than that of bare ITO structure because of the higher refractive index of graphene. To enhance the light trapping of graphene-based thin-film solar cells, a simple two-layer SiO(2)/SiC structure is proposed as antireflection coatings deposited on top of graphene transparent electrodes, and the thickness of each layer is optimized by differential evolution in order to enhance the optical absorption of a-Si:H thin-film solar cells to the greatest degree. The optimization results demonstrate the optimal SiO(2)/SiC/graphene structure can obtain 37.30% enhancement with respect to bare ITO structure, which has obviously exceeded the light-trapping enhancement of 34.15% for the optimal SiO(2)/SiC/ITO structure. Therefore, with the aid of the light-trapping structure, the graphene films are a very promising indium-free transparent electrode substitute for the conventional ITO electrode for use in cost-efficient thin-film silicon solar cells.

  15. Design optimization of thin-film/wafer-based tandem junction solar cells using analytical modeling

    NASA Astrophysics Data System (ADS)

    Davidson, Lauren; Toor, Fatima

    2016-03-01

    Several research groups are developing solar cells of varying designs and materials that are high efficiency as well as cost competitive with the single junction silicon (Si) solar cells commercially produced today. One of these solar cell designs is a tandem junction solar cell comprised of perovskite (CH3NH3PbI3) and silicon (Si). Loper et al.1 was able to create a 13.4% efficient tandem cell using a perovskite top cell and a Si bottom cell, and researchers are confident that the perovskite/Si tandem cell can be optimized in order to reach higher efficiencies without introducing expensive manufacturing processes. However, there are currently no commercially available software capable of modeling a tandem cell that is based on a thin-film based bottom cell and a wafer-based top cell. While PC1D2 and SCAPS3 are able to model tandem cells comprised solely of thin-film absorbers or solely of wafer-based absorbers, they result in convergence errors if a thin-film/wafer-based tandem cell, such as the perovskite/ Si cell, is modeled. The Matlab-based analytical model presented in this work is capable of modeling a thin-film/wafer-based tandem solar cell. The model allows a user to adjust the top and bottom cell parameters, such as reflectivity, material bandgaps, donor and acceptor densities, and material thicknesses, in order to optimize the short circuit current, open circuit voltage, and quantum efficiency of the tandem solar cell. Using the Matlab-based analytical model, we were able optimize a perovskite/Si tandem cell with an efficiency greater than 30%.

  16. Organometallic halide perovskite/barium di-silicide thin-film double-junction solar cells

    NASA Astrophysics Data System (ADS)

    Vismara, R.; Isabella, O.; Zeman, M.

    2016-04-01

    Barium di-silicide (BaSi2) is an abundant and inexpensive semiconductor with appealing opto-electrical properties. In this work we show that a 2-μm thick BaSi2-based thin-film solar cell can exhibit an implied photo-current density equal to 41.1 mA/cm2, which is higher than that of a state-of-the-art wafer-based c-Si hetero-junction solar cell. This performance makes BaSi2 an attractive absorber for high-performing thin-film and multi-junction solar cells. In particular, to assess the potential of barium di-silicide, we propose a thin-film double-junction solar cell based on organometallic halide perovskite (CH3NH3PbI3) as top absorber and BaSi2 as bottom absorber. The resulting modelled ultra-thin double-junction CH3NH3PbI3 / BaSi2 (< 2 μm) exhibits an implied total photo-current density equal to 38.65 mA/cm2 (19.84 mA/cm2 top cell, 18.81 mA/cm2 bottom cell) and conversion efficiencies up to 28%.

  17. Application of ICP-OES to the determination of CuIn(1-x)Ga(x)Se2 thin films used as absorber materials in solar cell devices.

    PubMed

    Fernández-Martínez, Rodolfo; Caballero, Raquel; Guillén, Cecilia; Gutiérrez, María Teresa; Rucandio, María Isabel

    2005-05-01

    CuIn(1-x)Ga(x)Se2 [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO3 alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  18. Solution-processed In2S3 buffer layer for chalcopyrite thin film solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Lin, Xianzhong; Ennaoui, Ahmed; Wolf, Christian; Lux-Steiner, Martha Ch.; Klenk, Reiner

    2016-02-01

    We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in different printing and coating techniques. Here we report on two techniques, namely spin-coating and inkjet printing. Active area efficiencies of 12.8% and 12.2% have been achieved for In2S3-buffered solar cells respectively, matching the performance of CdS-buffered cells prepared with the same batch of absorbers.

  19. Schottky solar cells based on CsSnI3 thin-films

    NASA Astrophysics Data System (ADS)

    Chen, Zhuo; Wang, Jian J.; Ren, Yuhang; Yu, Chonglong; Shum, Kai

    2012-08-01

    We describe a Schottky solar cell based on the perovskite semiconductor CsSnI3 thin-film. The cell consists of a simple layer structure of indium-tin-oxide/CsSnI3/Au/Ti on glass substrate. The measured power conversion efficiency is 0.9%, which is limited by the series and shunt resistance. The influence of light intensity on open-circuit voltage and short-circuit current supports the Schottky solar cell model. Additionally, the spectrally resolved short-circuit current was measured, confirming the unintentionally doped CsSnI3 is of p-type characteristics. The CsSnI3 thin-film was synthesized by alternately depositing layers of SnCl2 and CsI on glass substrate followed by a thermal annealing process.

  20. Operation of a Thin-Film Inflatable Concentrator System Demonstrated in a Solar Thermal Vacuum Environment

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.

    2002-01-01

    Thin-film inflatable solar concentrators offer significant advantages in comparison to stateof- the-art rigid panel concentrators, including low weight, low stowage volume, and simple gas deployment. From June 10 to 22, 2001, the ElectroMagnetic Radiation Control Experiment (EMRCE) Team used simulated solar energy to demonstrate the operation of an inflatable concentrator system at NASA Glenn Research Center's Tank 6 thermal vacuum facility. The joint Government/industry test team was composed of engineers and technicians from Glenn, the Air Force Research Laboratory, SRS Technologies, and ATK Thiokol Propulsion. The research hardware consisted of the following: 1) A thin-film inflatable concentrator; 2) The hexapod pointing and focus control system; 3) Two rigidized support struts using two candidate technologies - ultraviolet-rigidized glass and radiation-cured isographite.

  1. 2D modeling of silicon based thin film dual and triple junction solar cells

    NASA Astrophysics Data System (ADS)

    Xiao, Y. G.; Uehara, K.; Lestrade, M.; Li, Z. Q.; Li, Z. M. S.

    2009-08-01

    Based on Crosslight APSYS, thin film amorphous Si (a-Si:H)/microcrystalline (μc-Si) dual-junction (DJ) and a- Si:H/amorphous SiGe:H (a-SiGe:H)/μc-Si triple-junction (TJ) solar cells are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves for individual junctions are presented for current matching analyses. The whole DJ and TJ cell I-V curves are also presented and the results are discussed with respect to the top surface ZnO:Al TCO layer affinity. The interface texture effect is modeled with FDTD (finite difference time domain) module and results for top junction are presented. The modeling results give possible clues to achieve high efficiency for DJ and TJ thin film solar cells.

  2. Energy band alignment in chalcogenide thin film solar cells from photoelectron spectroscopy.

    PubMed

    Klein, Andreas

    2015-04-10

    Energy band alignment plays an important role in thin film solar cells. This article presents an overview of the energy band alignment in chalcogenide thin film solar cells with a particular focus on the commercially available material systems CdTe and Cu(In,Ga)Se2. Experimental results from two decades of photoelectron spectroscopy experiments are compared with density functional theory calculations taken from literature. It is found that the experimentally determined energy band alignment is in good agreement with theoretical predictions for many interfaces. These alignments, in particular the theoretically predicted alignments, can therefore be considered as the intrinsic or natural alignments for a given material combination. The good agreement between experiment and theory enables a detailed discussion of the interfacial composition of Cu(In,Ga)Se2/CdS interfaces in terms of the contribution of ordered vacancy compounds to the alignment of the energy bands. It is furthermore shown that the most important interfaces in chalcogenide thin film solar cells, those between Cu(In,Ga)Se2 and CdS and between CdS and CdTe are quite insensitive to the processing of the layers. There are plenty of examples where a significant deviation between experimentally-determined band alignment and theoretical predictions are evident. In such cases a variation of band alignment of sometimes more than 1 eV depending on interface preparation can be obtained. This variation can lead to a significant deterioration of device properties. It is suggested that these modifications are related to the presence of high defect concentrations in the materials forming the contact. The particular defect chemistry of chalcogenide semiconductors, which is related to the ionicity of the chemical bond in these materials and which can be beneficial for material and device properties, can therefore cause significant device limitations, as e.g. in the case of the CuInS2 thin film solar cells or for new

  3. Porous copper zinc tin sulfide thin film as photocathode for double junction photoelectrochemical solar cells.

    PubMed

    Dai, Pengcheng; Zhang, Guan; Chen, Yuncheng; Jiang, Hechun; Feng, Zhenyu; Lin, Zhaojun; Zhan, Jinhua

    2012-03-21

    Porous copper zinc tin sulfide (CZTS) thin film was prepared via a solvothermal approach. Compared with conventional dye-sensitized solar cells (DSSCs), double junction photoelectrochemical cells using dye-sensitized n-type TiO(2) (DS-TiO(2)) as the photoanode and porous p-type CZTS film as the photocathode shows an increased short circuit current, external quantum efficiency and power conversion efficiency.

  4. Synthesis of Cu2ZnSnS4 thin films by a precursor solution paste for thin film solar cell applications.

    PubMed

    Cho, Jin Woo; Ismail, Agus; Park, Se Jin; Kim, Woong; Yoon, Sungho; Min, Byoung Koun

    2013-05-22

    Cu2ZnSnS4 (CZTS) is a very promising semiconductor material when used for the absorber layer of thin film solar cells because it consists of only abundant and inexpensive elements. In addition, a low-cost solution process is applicable to the preparation of CZTS absorber films, which reduces the cost when this film is used for the production of thin film solar cells. To fabricate solution-processed CZTS thin film using an easily scalable and relatively safe method, we suggest a precursor solution paste coating method with a two-step heating process (oxidation and sulfurization). The synthesized CZTS film was observed to be composed of grains of a size of ~300 nm, showing an overall densely packed morphology with some pores and voids. A solar cell device with this film as an absorber layer showed the highest efficiency of 3.02% with an open circuit voltage of 556 mV, a short current density of 13.5 mA/cm(2), and a fill factor of 40.3%. We also noted the existence of Cd moieties and an inhomogeneous Zn distribution in the CZTS film, which may have been triggered by the presence of pores and voids in the CZTS film.

  5. INVESTIGATION OF THIN FILM CADMIUM SULFIDE SOLAR CELLS.

    DTIC Science & Technology

    SOLAR CELLS , *CADMIUM COMPOUNDS, FILMS, SULFIDES, VAPOR PLATING, VACUUM APPARATUS, SINGLE CRYSTALS, TITANIUM, COPPER COMPOUNDS, CHLORIDES, INDIUM, MOLYBDENUM, SILICON COMPOUNDS, MONOXIDES, SURFACE PROPERTIES, ENERGY CONVERSION.

  6. PEDOT:PSS emitters on multicrystalline silicon thin-film absorbers for hybrid solar cells

    NASA Astrophysics Data System (ADS)

    Junghanns, Marcus; Plentz, Jonathan; Andrä, Gudrun; Gawlik, Annett; Höger, Ingmar; Falk, Fritz

    2015-02-01

    We fabricated an efficient hybrid solar cell by spin coating poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) on planar multicrystalline Si (mc-Si) thin films. The only 5 μm thin Si absorber layers were prepared by diode laser crystallization of amorphous Si deposited by electron beam evaporation on glass. On these absorber layers, we studied the effect of SiOx and Al2O3 terminated Si surfaces. The short circuit density and power conversion efficiency (PCE) of the mc-Si/Al2O3/PEDOT:PSS solar cell increase from 20.6 to 25.4 mA/cm2 and from 7.3% to 10.3%, respectively, as compared to the mc-Si/SiOx/PEDOT:PSS cell. Al2O3 lowers the interface recombination and improves the adhesion of the polymer film on the hydrophobic mc-Si thin film. Open circuit voltages up to 604 mV were reached. This study demonstrates the highest PCE so far of a hybrid solar cell with a planar thin film Si absorber.

  7. PEDOT:PSS emitters on multicrystalline silicon thin-film absorbers for hybrid solar cells

    SciTech Connect

    Junghanns, Marcus; Plentz, Jonathan Andrä, Gudrun; Gawlik, Annett; Höger, Ingmar; Falk, Fritz

    2015-02-23

    We fabricated an efficient hybrid solar cell by spin coating poly(3,4-ethylene-dioxythiophene):polystyrenesulfonate (PEDOT:PSS) on planar multicrystalline Si (mc-Si) thin films. The only 5 μm thin Si absorber layers were prepared by diode laser crystallization of amorphous Si deposited by electron beam evaporation on glass. On these absorber layers, we studied the effect of SiO{sub x} and Al{sub 2}O{sub 3} terminated Si surfaces. The short circuit density and power conversion efficiency (PCE) of the mc-Si/Al{sub 2}O{sub 3}/PEDOT:PSS solar cell increase from 20.6 to 25.4 mA/cm{sup 2} and from 7.3% to 10.3%, respectively, as compared to the mc-Si/SiO{sub x}/PEDOT:PSS cell. Al{sub 2}O{sub 3} lowers the interface recombination and improves the adhesion of the polymer film on the hydrophobic mc-Si thin film. Open circuit voltages up to 604 mV were reached. This study demonstrates the highest PCE so far of a hybrid solar cell with a planar thin film Si absorber.

  8. Development of a Thin Film Solar Cell Interconnect for the Powersphere Concept

    NASA Technical Reports Server (NTRS)

    Simburger, Edward J.; Matsumoto, James H.; Giants, Thomas W.; Garcia, Alexander, III; Liu, Simon; Rawal, Suraj P.; Perry, Alan R.; Marshall, Craig H.; Lin, John K.; Scarborough, Stephen

    2003-01-01

    Progressive development of microsatellite technologies has resulted in increased demand for lightweight electrical power subsystems including solar arrays. The use of thin film photovoltaics has been recognized as a key solution to meet the power needs. The lightweight cells can generate sufficient power and still meet critical mass requirements. Commercially available solar cells produced on lightweight substrates are being studied as an option to fulfill the power needs. The commercially available solar cells are relatively inexpensive and have a high payoff potential. Commercially available thin film solar cells are primarily being produced for terrestrial applications. The need to convert the solar cell from a terrestrial to a space compatible application is the primary challenge. Solar cell contacts, grids and interconnects need to be designed to be atomic oxygen resistant and withstand rapid thermal cycling environments. A mechanically robust solar cell interconnect is also required in order to withstand handling during fabrication and survive during launch. The need to produce the solar cell interconnects has been identified as a primary goal of the Powersphere program and is the topic of this paper. Details of the trade study leading to the final design involving the solar cell wrap around contact, flex blanket, welding process, and frame will be presented at the conference.

  9. Quantum efficiency enhancement in selectively transparent silicon thin film solar cells by distributed Bragg reflectors.

    PubMed

    Kuo, M Y; Hsing, J Y; Chiu, T T; Li, C N; Kuo, W T; Lay, T S; Shih, M H

    2012-11-05

    This work demonstrated a-Si:H thin-film solar cells with backside TiO(2)/ SiO(2) distributed Bragg reflectors (DBRs) for applications involving building-integrated photovoltaics (BIPVs). Selectively transparent solar cells are formed by adjusting the positions of the DBR stop bands to allow the transmission of certain parts of light through the solar cells. Measurement and simulation results indicate that the transmission of blue light (430 ~500 nm) with the combination of three DBR mirrors has the highest increase in conversion efficiency.

  10. Quantum efficiency enhancement in selectively transparent silicon thin film solar cells by distributed Bragg reflectors.

    PubMed

    Kuo, M Y; Hsing, J Y; Chiu, T T; Li, C N; Kuo, W T; Lay, T S; Shih, M H

    2012-11-05

    This work demonstrated a-Si:H thin-film solar cells with backside TiO(2) / SiO(2) distributed Bragg reflectors (DBRs) for applications involving building-integrated photovoltaics (BIPVs). Selectively transparent solar cells are formed by adjusting the positions of the DBR stop bands to allow the transmission of certain parts of light through the solar cells. Measurement and simulation results indicate that the transmission of blue light (430 ~500 nm) with the combination of three DBR mirrors has the highest increase in conversion efficiency.

  11. Drift Mobility Measurements and Electrical Characterization in Thin Film Cadmium Telluride Solar Cells

    NASA Astrophysics Data System (ADS)

    Long, Qi

    Thin film CdTe solar cells are leading the production in the thin film photovoltaic industry for the recent few years. The electric properties and mechanism for fabrication of high efficiency solar cells are still not well established. In this thesis, I'll report electron and hole drift mobilities measurements in thin film CdTe solar cells based on two characterization methods: time-of-flight and photocapacitance. For a deposition process similar to that used for high-efficiency cells, the electron drift mobilities are in the range 10-1 -- 100 cm2/Vs, and holes are in the range 100 -- 101 cm2/Vs. The electron drift mobilities are three orders of magnitude smaller than those measured in single crystal CdTe, the hole mobilities are about ten times smaller. Cells were examined before and after a vapor phase treatment with CdCl2; treatment had little effect on the hole drift mobility, but decreased the electron mobility. The electron mobility shows an interesting inverse correlation with the open-circuit voltage for the CdTe coupons with and without the CdCl2 treatment. We speculate that this correlation is due to the diffusion limited recombination. We also discuss the mechanisms reducing the mobilities from the single crystal values. In this thesis, we are able to exclude bandtail trapping and dispersion as a mechanism for the small drift mobilities in thin film CdTe. Other mechanisms like classic scattering, grain boundaries effect, and also polaron interaction will also be discussed in this thesis. All mechanisms mentioned above show little evidence on the influence to the mobility value. The true reason for such a huge change of the drift mobility from its single crystal values still need more interpretations.

  12. Thin film solar cell inflatable ultraviolet rigidizable deployment hinge

    NASA Technical Reports Server (NTRS)

    Simburger, Edward J. (Inventor); Matsumoto, James H. (Inventor); Giants, Thomas W. (Inventor); Garcia, III, Alec (Inventor); Perry, Alan R. (Inventor); Rawal, Suraj (Inventor); Marshall, Craig H. (Inventor); Lin, John K. H. (Inventor); Day, Jonathan Robert (Inventor); Kerslake, Thomas W. (Inventor)

    2010-01-01

    A flexible inflatable hinge includes curable resin for rigidly positioning panels of solar cells about the hinge in which wrap around contacts and flex circuits are disposed for routing power from the solar cells to the power bus further used for grounding the hinge. An indium tin oxide and magnesium fluoride coating is used to prevent static discharge while being transparent to ultraviolet light that cures the embedded resin after deployment for rigidizing the inflatable hinge.

  13. Plasmonic light trapping in thin-film Si solar cells

    NASA Astrophysics Data System (ADS)

    Spinelli, P.; Ferry, V. E.; van de Groep, J.; van Lare, M.; Verschuuren, M. A.; Schropp, R. E. I.; Atwater, H. A.; Polman, A.

    2012-02-01

    Plasmonic nanostructures have been recently investigated as a possible way to improve absorption of light in solar cells. The strong interaction of small metal nanostructures with light allows control over the propagation of light at the nanoscale and thus the design of ultrathin solar cells in which light is trapped in the active layer and efficiently absorbed. In this paper we review some of our recent work in the field of plasmonics for improved solar cells. We have investigated two possible ways of integrating metal nanoparticles in a solar cell. First, a layer of Ag nanoparticles that improves the standard antireflection coating used for crystalline and amorphous silicon solar cells has been designed and fabricated. Second, regular and random arrays of metal nanostructures have been designed to couple light in waveguide modes of thin semiconductor layers. Using a large-scale, relative inexpensive nano-imprint technique, we have designed a back-contact light trapping surface for a-Si:H solar cells which show enhanced efficiency over standard randomly textured cells.

  14. High efficiency thin-film CuIn1-xGaxSe2 photovoltaic cells using a Cd1-xZnxS buffer layer

    NASA Astrophysics Data System (ADS)

    Bhattacharya, R. N.; Contreras, M. A.; Egaas, B.; Noufi, R. N.; Kanevce, A.; Sites, J. R.

    2006-12-01

    The authors have fabricated 19.52% thin-film CuIn1-xGaxSe2 (CIGS)-based photovoltaic devices using single layer chemical bath deposited Cd1-xZnxS (CdZnS) buffer layer. The efficiency equals the world record for any thin-film solar cell and is achieved with reduced optical absorption in the window layer. Using current-voltage, quantum efficiency, and capacitance-voltage measurements, the CIGS/CdZnS device parameters are directly compared with those of CIGS/CdS devices fabricated with equivalent absorbers.

  15. Full potential of radial junction Si thin film solar cells with advanced junction materials and design

    NASA Astrophysics Data System (ADS)

    Qian, Shengyi; Misra, Soumyadeep; Lu, Jiawen; Yu, Zhongwei; Yu, Linwei; Xu, Jun; Wang, Junzhuan; Xu, Ling; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-07-01

    Combining advanced materials and junction design in nanowire-based thin film solar cells requires a different thinking of the optimization strategy, which is critical to fulfill the potential of nano-structured photovoltaics. Based on a comprehensive knowledge of the junction materials involved in the multilayer stack, we demonstrate here, in both experimental and theoretical manners, the potential of hydrogenated amorphous Si (a-Si:H) thin film solar cells in a radial junction (RJ) configuration. Resting upon a solid experimental basis, we also assess a more advanced tandem RJ structure with radially stacking a-Si:H/nanocrystalline Si (nc-Si:H) PIN junctions, and show that a balanced photo-current generation with a short circuit current density of Jsc = 14.2 mA/cm2 can be achieved in a tandem RJ cell, while reducing the expensive nc-Si:H absorber thickness from 1-3 μ m (in planar tandem cells) to only 120 nm. These results provide a clearly charted route towards a high performance Si thin film photovoltaics.

  16. New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Eijt, S. W. H.; Shi, W.; Mannheim, A.; Butterling, M.; Schut, H.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R. W.; Callewaert, V.; Saniz, R.; Partoens, B.; Barbiellini, B.; Bansil, A.; Melskens, J.; Zeman, M.; Smets, A. H. M.; Kulbak, M.; Hodes, G.; Cahen, D.; Brück, E.

    2017-01-01

    Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.

  17. Large area CuInSe2 thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Mickelsen, R. A.; Stanbery, B. J.; Avery, J. E.; Chen, Wen S.; Devaney, W. E.

    The simulated AM1 efficiency of evaporated CuInSe2/CdZnS polycrystalline thin-film solar cells prepared in a production-oriented, monolithically interconnected submodule configuration of 91 sq cm area on low-cost glass substrates has been increased from 6.2 to 9.6 percent. The results are attributed to the formation of coevaporated selenide films with improved compositional and structural uniformities. Submodule structures and fabrication processes, including electron gun evaporation of the mixed CdZnS films, are presented along with the submodule photovoltaic performances. The preparation of silicon oxide and nitride optical thin films by a plasma-enhanced CVD process and their application as quarter-wavelength double-layer antireflection coatings are discussed.

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

    NASA Astrophysics Data System (ADS)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

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

  19. Optimization of microcrystalline silicon thin film solar cell isolation processing parameters using ultraviolet laser

    NASA Astrophysics Data System (ADS)

    Kuo, Chung-Feng Jeffery; Tu, Hung-Min; Liang, Shin-Wei; Tsai, Wei-Lun

    2010-09-01

    This study used ultraviolet laser to perform the microcrystalline silicon thin film solar cell isolation scribing process, and applied the Taguchi method and an L 18 orthogonal array to plan the experiment. The isolation scribing materials included ZnO:Al, AZO transparent conductive film with a thickness of 200 nm, microcrystalline silicon thin film at 38% crystallinity and of thickness of 500 nm, and the aluminum back contact layer with a thickness of 300 nm. The main objective was to ensure the success of isolation scribing. After laser scribing isolation, using the minimum scribing line width, the flattest trough bottom, and the minimum processing edge surface bumps as the quality characteristics, this study performed main effect analysis and applied the ANOVA (analysis of variance) theory of the Taguchi method to identify the single quality optimal parameter. It then employed the hierarchical structure of the AHP (analytic hierarchy process) theory to establish the positive contrast matrix. After consistency verification, global weight calculation, and priority sequencing, the optimal multi-attribute parameters were obtained. Finally, the experimental results were verified by a Taguchi confirmation experiment and confidence interval calculation. The minimum scribing line width of AZO (200 nm) was 45.6 μm, the minimum scribing line width of the microcrystalline silicon (at 38% crystallinity) was 50.63 μm and the minimum line width of the aluminum thin film (300 nm) was 30.96 μm. The confirmation experiment results were within the 95% confidence interval, verifying that using ultraviolet laser in the isolation scribing process for microcrystalline silicon thin film solar cell has high reproducibility.

  20. Thin film solar cell configuration and fabrication method

    DOEpatents

    Menezes, Shalini

    2009-07-14

    A new photovoltaic device configuration based on an n-copper indium selenide absorber and a p-type window is disclosed. A fabrication method to produce this device on flexible or rigid substrates is described that reduces the number of cell components, avoids hazardous materials, simplifies the process steps and hence the costs for high volume solar cell manufacturing.

  1. Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cells.

    PubMed

    Chirilă, Adrian; Reinhard, Patrick; Pianezzi, Fabian; Bloesch, Patrick; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Keller, Debora; Gretener, Christina; Hagendorfer, Harald; Jaeger, Dominik; Erni, Rolf; Nishiwaki, Shiro; Buecheler, Stephan; Tiwari, Ayodhya N

    2013-12-01

    Thin-film photovoltaic devices based on chalcopyrite Cu(In,Ga)Se2 (CIGS) absorber layers show excellent light-to-power conversion efficiencies exceeding 20%. This high performance level requires a small amount of alkaline metals incorporated into the CIGS layer, naturally provided by soda lime glass substrates used for processing of champion devices. The use of flexible substrates requires distinct incorporation of the alkaline metals, and so far mainly Na was believed to be the most favourable element, whereas other alkaline metals have resulted in significantly inferior device performance. Here we present a new sequential post-deposition treatment of the CIGS layer with sodium and potassium fluoride that enables fabrication of flexible photovoltaic devices with a remarkable conversion efficiency due to modified interface properties and mitigation of optical losses in the CdS buffer layer. The described treatment leads to a significant depletion of Cu and Ga concentrations in the CIGS near-surface region and enables a significant thickness reduction of the CdS buffer layer without the commonly observed losses in photovoltaic parameters. Ion exchange processes, well known in other research areas, are proposed as underlying mechanisms responsible for the changes in chemical composition of the deposited CIGS layer and interface properties of the heterojunction.

  2. Radiation resistance of thin-film solar cells for space photovoltaic power

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.; Landis, Geoffrey A.

    1991-01-01

    Copper indium diselenide, cadmium telluride, and amorphous silicon alloy solar cells have achieved noteworthy performance and are currently being studied for space power applications. Cadmium sulfide cells had been the subject of much effort but are no longer considered for space applications. A review is presented of what is known about the radiation degradation of thin film solar cells in space. Experimental cadmium telluride and amorphous silicon alloy cells are reviewed. Damage mechanisms and radiation induced defect generation and passivation in the amorphous silicon alloy cell are discussed in detail due to the greater amount of experimental data available.

  3. Needle Profile Grating Structure for Absorption Enhancement in GaAs Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Yile; Zhang, Xu; Guo, Minqiang; Sun, Xiaohong; Yu, Yanguang; Xi, Jiangtao

    2015-11-01

    We conduct a systematic study of thin film solar cells consisting of a GaAs needle profile (NP) grating structure as a light-trapping layer. The influence of geometric parameters on the optical absorption of the NP grating is investigated using rigorous coupled wave analysis and the finite element method. This type of structure can lead to broadband optical absorption enhancement throughout the wavelength range that we studied. Our simulation results reveal that the absorption efficiency of NP grating can be improved significantly compared with its rectangular grating counterpart. The proposed structure is expected to illuminate the design and fabrication of high-efficiency solar cells.

  4. Role of 2-D periodic symmetrical nanostructures in improving efficiency of thin film solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jiang, Liyong; Li, Xiangyin

    2016-01-01

    We systematically investigated several different nanostructures in crystalline silicon (c-Si) thin film solar cells and then proposed a brand-new structure with two dimensional (2-D) periodic dielectric cylinders on the top and annular metal columns on bottom surface to enhance the optical harvesting. The periodic symmetrical nanostructures affect the solar cell efficiency due to the grating diffraction effect of dielectric columns and surface plasmon polaritons (SPPs) effect induced by metal nanostructures at the dielectric-metal interface. About 52.1% more optical absorption and 33.3% more power conversion efficiency are obtained, and the maximum short current reaches to 33.24 mA/cm2.

  5. Antireflective submicrometer gratings on thin-film silicon solar cells for light-absorption enhancement.

    PubMed

    Song, Young Min; Yu, Jae Su; Lee, Yong Tak

    2010-02-01

    This study reports highly efficient light-absorbing structures based on submicrometer gratings (SMGs) for thin-film crystalline silicon solar cells. The integration of SMGs into the cell structure leads to superior broadband antireflection properties compared to conventional antireflection coatings. With careful design optimization, an improvement of the cell efficiency of nearly 25.1% was obtained compared to double-layer coated solar cells. Optimized SMG structures were fabricated on a silicon substrate using interference lithography and a lenslike shape transfer process. The fabricated SMG structures exhibited low reflectivity in the wavelength range of 300-1200 nm, indicating good agreement with the simulated results.

  6. Photoelectrochemistry of Cu(In,Ga)Se2 thin-films fabricated by sequential pulsed electrodeposition

    NASA Astrophysics Data System (ADS)

    Mandati, Sreekanth; Sarada, Bulusu V.; Dey, Suhash R.; Joshi, Shrikant V.

    2015-01-01

    A novel approach for the fabrication of compact stoichiometric copper indium gallium selenium (CIGS) thin-films is reported. It uses a solution of CuCl2, GaCl3 and H2SeO3, pH adjusted with HCl with LiCl as additive employing a high purity graphite plate anode and Mo sputtered glass cathode during a simplified sequential pulsed current electrodeposition which avoids impurities from the use of a reference electrode during deposition and a separate selenization step. A Cu-Ga-Se film is optimally deposited by optimizing the deposition voltage, followed by deposition of In from InCl3 solution, and then annealing of the Cu-Ga-Se/In thin-film in an Argon atmosphere at 550 °C. A single phase chalcopyrite CIGS forms with a compact morphology and well-controlled composition of individual elements. The flat-band potential and carrier density of CIGS thin-films are -0.15 V and 2.6 × 1016 cm-3, respectively, as determined by Mott-Schottky studies. The photoelectrochemical performance of CIGS films shows a photocurrent density of -0.8 mA cm-2 at -0.4 V vs. SCE, an eight fold increment compared to our previous reported value. This simplified preparation using pulse plating gives superior quality CIGS films which are promising for application in thin-film solar cells and photoelectrochemical cells.

  7. Solar cells from thin films prepared by periodic pulse electrodeposition

    NASA Astrophysics Data System (ADS)

    Morris, G. C.; Vanderveen, R. J.

    1996-02-01

    Periodic pulse electrodeposition (PPE) of CdS and CdTe polycrystalline films is reported. These films adhered more strongly to FTO than to ITO and better to either substrate than films prepared by DC methods. Solar cells of the type glass/conducting transparent oxide/nCdS/pCdTe/Au had superior properties when PPE CdS films were used. A CdCl 2 treatment of the CdS layer was an essential fabrication step for stable, efficient, larger area cells.

  8. Challenges to Scaling CIGS Photovoltaics

    NASA Astrophysics Data System (ADS)

    Stanbery, B. J.

    2011-03-01

    The challenges of scaling any photovoltaic technology to terawatts of global capacity are arguably more economic than technological or resource constraints. All commercial thin-film PV technologies are based on direct bandgap semiconductors whose absorption coefficient and bandgap alignment with the solar spectrum enable micron-thick coatings in lieu to hundreds of microns required using indirect-bandgap c-Si. Although thin-film PV reduces semiconductor materials cost, its manufacture is more capital intensive than c-Si production, and proportional to deposition rate. Only when combined with sufficient efficiency and cost of capital does this tradeoff yield lower manufacturing cost. CIGS has the potential to become the first thin film technology to achieve the terawatt benchmark because of its superior conversion efficiency, making it the only commercial thin film technology which demonstrably delivers performance comparable to the dominant incumbent, c-Si. Since module performance leverages total systems cost, this competitive advantage bears directly on CIGS' potential to displace c-Si and attract the requisite capital to finance the tens of gigawatts of annual production capacity needed to manufacture terawatts of PV modules apace with global demand growth.

  9. Electrodeposition of antimony selenide thin films and application in semiconductor sensitized solar cells.

    PubMed

    Ngo, T Tuyen; Chavhan, Sudam; Kosta, Ivet; Miguel, Oscar; Grande, Hans-Jurgen; Tena-Zaera, Ramón

    2014-02-26

    Sb2Se3 thin films are proposed as an alternative light harvester for semiconductor sensitized solar cells. An innovative electrodeposition route, based on aqueous alkaline electrolytes, is presented to obtain amorphous Sb2Se3. The amorphous to crystalline phase transition takes place during a soft thermal annealing in Ar atmosphere. The potential of the Sb2Se3 electrodeposited thin films in semiconductor sensitized solar cells is evaluated by preparing TiO2/Sb2Se3/CuSCN planar heterojunction solar cells. The resulting devices generate electricity from the visible and NIR photons, exhibiting the external quantum efficiency onset close to 1050 nm. Although planar architecture is not optimized in terms of charge carrier collection, photocurrent as high as 18 mA/cm(2), under simulated (AM1.5G) solar light, is achieved. Furthermore, the effect of the Sb2Se3 thickness and microstructural properties on the photocurrent is analyzed, suggesting the hole transport is the main limiting mechanism. The present findings provide significant insights to design efficient semiconductor sensitized solar cells based on advanced architectures (e.g., nanostructured and tandem), opening wide possibilities for progresses in this emerging photovoltaics technology.

  10. Sinusoidal nanotextures for light management in silicon thin-film solar cells.

    PubMed

    Köppel, G; Rech, B; Becker, C

    2016-04-28

    Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

  11. Advanced APCVD-processes for high-temperature grown crystalline silicon thin film solar cells.

    PubMed

    Driessen, Marion; Merkel, Benjamin; Reber, Stefan

    2011-09-01

    Crystalline silicon thin film (cSiTF) solar cells based on the epitaxial wafer-equivalent (EpiWE) concept combine advantages of wafer-based and thin film silicon solar cells. In this paper two processes beyond the standard process sequence for cSiTF cell fabrication are described. The first provides an alternative to wet chemical saw damage removal by chemical vapor etching (CVE) with hydrogen chloride in-situ prior to epitaxial deposition. This application decreases the number of process and handling steps. Solar cells fabricated with different etching processes achieved efficiencies up to 14.7%. 1300 degrees C etching temperature led to better cell results than 1200 degrees C. The second investigated process aims for an improvement of cell efficiency by implementation of a reflecting interlayer between substrate and active solar cell. Some characteristics of epitaxial lateral overgrowth (ELO) of a patterned silicon dioxide film in a lab-type reactor constructed at Fraunhofer ISE are described and first solar cell results are presented.

  12. Sinusoidal nanotextures for light management in silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Köppel, G.; Rech, B.; Becker, C.

    2016-04-01

    Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

  13. Design principle for absorption enhancement with nanoparticles in thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Yuanpei; Xuan, Yimin

    2015-07-01

    The use of nanoparticles in solar cells has created many controversies. In this paper, different mechanisms of nanoparticles with different materials with diameters varying from 50 to 200 nm, surface coverage at 5, 20, and 60 %, and different locations are analyzed systematically for efficient light trapping in a thin-film c-Si solar cell. Mie theory and the finite difference time domain method are used for analysis to give a design principle with nanoparticles for the solar cell application. Metals exhibit plasmonic resonances and angular scattering, while dielectrics show anti-reflection and scattering in the incident direction. A table is given to summarize the advantages and disadvantages in different conditions. The silicon absorption enhancement with nanoparticles on top is mainly in the shorter wavelengths below 700 nm, and both Al and SiO2 nanoparticles with diameter around 100 nm show the most significant enhancement. The silicon absorption enhancement with embedded nanoparticles takes place in the longer wavelengths over 700 nm, and Ag and SiO2 nanoparticles with larger diameter around 200 nm perform better. However, the light absorbed by Ag nanoparticles will be converted to heat and will lead to decrease in cell efficiency; hence, the choice of metallic nanoparticles in applications to solar cells should be carefully considered. The design principle proposed in this work gives a guideline by choosing reasonable parameters for the different requirements in the application of thin-film solar cells.

  14. Low-Cost, Light Weight, Thin Film Solar Concentrator

    NASA Technical Reports Server (NTRS)

    Ganapathi, G.; Palisoc, A.; Nesmith, B.; Greschik, G.; Gidanian, K.; Kindler, A.

    2013-01-01

    This research addresses a cost barrier towards achieving a solar thermal collector system with an installed cost of $75/sq m and meet the Department of Energy's (DOE's) performance targets for optical errors, operations during windy conditions and lifetime. Current concentrators can cost as much as 40-50% of the total installed costs for a CSP plant. In order to reduce the costs from current $200-$250/sq m, it is important to focus on the overall system. The reflector surface is a key cost driver, and our film-based polymer reflector will help significantly in achieving DOE's cost target of $75/sq m. The ease of manufacturability, installation and replacement make this technology a compelling one to develop. This technology can be easily modified for a variety of CSP options including heliostats, parabolic dishes and parabolic troughs.

  15. High efficiency thin-film GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Zwerdling, S.; Wang, K. L.; Yeh, Y. C. M.

    1981-01-01

    The paper demonstrates the feasibility of producing high-efficiency GaAs solar cells with high power-to-weight ratios by organic metallic chemical vapor deposition (OM-CVD) growth of thin epi-layers on suitable substrates. An AM1 conversion efficiency of 18% (14% AM0), or 17% (13% AM0) with a 5% grid coverage is achieved for a single-crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer. Thin GaAs epi-layers OM-CVD grown can be fabricated with good crystallographic quality using a Si-substrate on which a thin Ge epi-interlayer is first deposited by CVD from GeH4 and processed for improved surface morphology

  16. On-Orbit Demonstration of a Lithium-Ion Capacitor and Thin-Film Multijunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Kukita, Akio; Takahashi, Masato; Shimazaki, Kazunori; Kobayashi, Yuki; Sakai, Tomohiko; Toyota, Hiroyuki; Takahashi, Yu; Murashima, Mio; Uno, Masatoshi; Imaizumi, Mitsuru

    2014-08-01

    This paper describes an on-orbit demonstration of the Next-generation Small Satellite Instrument for Electric power systems (NESSIE) on which an aluminum- laminated lithium-ion capacitor (LIC) and a lightweight solar panel called KKM-PNL, which has space solar sheets using thin-film multijunction solar cells, were installed. The flight data examined in this paper covers a period of 143 days from launch. We verified the integrity of an LIC constructed using a simple and lightweight mounting method: no significant capacitance reduction was observed. We also confirmed that inverted metamorphic multijunction triple-junction thin-film solar cells used for evaluation were healthy at 143 days after launch, because their degradation almost matched the degradation predictions for dual-junction thin-film solar cells.

  17. Exploring the potential of semiconducting BaSi2 for thin-film solar cell applications

    NASA Astrophysics Data System (ADS)

    Suemasu, Takashi; Usami, Noritaka

    2017-01-01

    Semiconducting barium disilicide (BaSi2), which is composed of earth-abundant elements, has attractive features for thin-film solar cell applications. Both a large absorption coefficient comparable to copper indium gallium diselenide and a minority-carrier diffusion length much larger than the grain size of BaSi2 can be used to improve solar cell properties. In this review article, we explore the potential of semiconducting BaSi2 film for thin-film solar cell applications. We start by describing its crystal and energy band structure, followed by discussing thin-film growth techniques and the optical and electrical properties of BaSi2 films. We use a first-principles calculation based on density-functional theory to calculate the position of the Fermi level to predict the carrier type of impurity-doped BaSi2 films using either a group 13 or 15 element, and compare the calculated results with the experimental ones. Special attention was paid to the minority-carrier properties, such as minority-carrier lifetime, minority-carrier diffusion length, and surface passivation. The potential variations across the grain boundaries measured by Kelvin-probe force microscopy allowed us to detect a larger minority-carrier diffusion length in BaSi2 on Si(1 1 1) compared with BaSi2 on Si(0 0 1). Finally, we demonstrate the operation of p-BaSi2/n-Si heterojunction solar cells and discuss prospects for future development.

  18. Analysis of the p+/p window layer of thin film solar cells by simulation

    NASA Astrophysics Data System (ADS)

    Aiguo, Lin; Jianning, Ding; Ningyi, Yuan; Shubo, Wang; Guanggui, Cheng; Chao, Lu

    2012-02-01

    The application of a p+/p configuration in the window layer of hydrogenated amorphous silicon thin film solar cells is simulated and analyzed utilizing an AMPS-1D program. The differences between p+-p—i—n configuration solar cells and p—i—n configuration solar cells are pointed out. The effects of dopant concentration, thickness of p+-layer, contact barrier height and defect density on solar cells are analyzed. Our results indicate that solar cells with a p+-p—i—n configuration have a better performance. The open circuit voltage and short circuit current were improved by increasing the dopant concentration of the p+ layer and lowering the front contact barrier height. The defect density at the p/i interface which exceeds two orders of magnitude in the intrinsic layer will deteriorate the cell property.

  19. Optical simulation of photonic random textures for thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Bittkau, K.; Hoffmann, A.

    2014-05-01

    We investigate light-scattering textures for the application in thin-film solar cells which consist of a random texture, as commonly applied in thin-film solar cells, that are superimposed with a two-dimensional grating structure. Those textures are called photonic random texture. A scalar optical model is applied to describe the light-scattering properties of those textures. With this model, we calculate the angular resolved light scattering into silicon in transmission at the front contact and for reflection at the back contact of a microcrystalline silicon solar cell. A quantity to describe the lighttrapping efficiency is derived and verified by rigorous diffraction theory. We show that this quantity is well suitable to predict the short-circuit current density in the light-trapping regime, where the absorptance is low. By varying the period, height and shape of the unit cell, we optimize the grating structure with respect to the total generated current density. The maximal predicted improvement in the spectral range from 600-900 nm is found to be about 3 mA/cm2 compared to the standard random texture and about 6 mA/cm2 compared to a flat solar cell.

  20. n +-Microcrystalline-Silicon Tunnel Layer in Tandem Si-Based Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Lee, Hsin-Ying; Chen, Kuan-Hao

    2016-10-01

    In this study, the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell deposited using plasma-enhanced chemical vapor deposition were cascaded for forming the tandem Si-based thin film solar cells to absorb the wide solar spectrum. To further improve the performances of the tandem Si-based thin film solar cells, a 5-nm-thick n +-microcrystalline-Si ( n +-μc-Si) tunnel layer deposited using the laser-assisted plasma-enhanced chemical vapor deposition was inserted between the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell. Since both the plasma and the CO2 laser were simultaneously utilized to efficiently decompose the reactant and doping gases, the carrier concentration and the carrier mobility of the n +-μc-Si tunnel layer were significantly improved. The ohmic contact formed between the p-SiC layer and the n +-μc-Si tunnel layer with low resistance was beneficial to the generated current transportation and the carrier recombination rate. Therefore, the conversion efficiency of the tandem solar cells was promoted from 8.57% and 8.82% to 9.91% compared to that without tunnel layer and with 5-nm-thick n +-amorphous-Si tunnel layer.

  1. A facile fabrication of chemically converted graphene oxide thin films and their uses as absorber materials for solar cells

    NASA Astrophysics Data System (ADS)

    Adelifard, Mehdi; Darudi, Hosein

    2016-07-01

    There is a great interest in the use of graphene sheets in thin film solar cells with low-cost and good-optoelectronic properties. Here, the production of absorbent conductive reduced graphene oxide (RGO) thin films was investigated. RGO thin films were prepared from spray-coated graphene oxide (GO) layers at various substrate temperature followed by a simple hydrazine-reducing method. The structural, morphological, optical, and electrical characterizations of graphene oxide (GO) and RGO thin films were investigated. X-ray diffraction analysis showed a phase shift from GO to RGO due to hydrazine treatment, in agreement with the FTIR spectra of the layers. FESEM images clearly exhibited continuous films resulting from the overlap of graphene nanosheets. The produced low-cost thin films had high absorption coefficient up to 1.0 × 105 cm-1, electrical resistance as low as 0.9 kΩ/sq, and effective optical band gap of about 1.50 eV, close to the optimum value for solar conversion. The conductive absorbent properties of the reduced graphene oxide thin films would be useful to develop photovoltaic cells.

  2. Engineering polymer-fullerene thin films and solar cells with external fields

    NASA Astrophysics Data System (ADS)

    Cabral, Joao

    2014-03-01

    Trace amounts of nanoparticles, including fullerenes, can impart stability to thin polymer films against dewetting by the combined effects of pinning the contact lines of dewetting holes and by effectively altering the polymer-substrate interaction. Polymer nanocomposite (meta)stable thin films can yield well-defined morphologies from uniform to spinodal-like, via spontaneous polymer-nanoparticle phase separation and crystallization. Confinement breaks the structural isotropy and generally causes (partial) segregation of components orthogonally to the film surface. Surface energy patterning can thus modulate composition and morphology, both in plane and normal to the surface. Further, UV-visible, and even background, light exposure, in both solutions and melts, is shown to tune the solution stucture and morphology of dewetting and phase separating polymer-fullerene thin films. Neutron reflectivity allows us to locate the various constituents within the film. We find a coupling of fullerene photo-sensitivity and both self-assembly processes which results in controlled pattern formation, and we illustrate the potential with a model polymer-fullerene circuit pattern. We then translate this approach into the directed assembly of energy harvesting bulk heterojunctions thin films. Indeed, a key challenge to the commercialization of organic solar cells remains the achievement of morphological stability, particularly under thermal stress conditions. The directed assembly a blend polymer:PC60BM solar cells via a simple light processing step results in a 10-100 fold increase in device thermal stability and, under certain conditions, enhanced device performance. The enhanced stability is linked to the light-induced oligomerisation of PC60BM that effectively hinders diffusion and crystallization in blends. This effect appears to be general and promises to be an effective and cost-effective strategy to optimize fullerene-based solar cell performance.

  3. Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures.

    PubMed

    Hilali, Mohamed M; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S V

    2012-10-12

    In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent.

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

    NASA Astrophysics Data System (ADS)

    Fang, Fang

    2011-12-01

    Public awareness of the increasing energy crisis and the related serious environmental concerns has led to a significantly growing demand for alternative clean and renewable energy resources. Thin film are widely applied in multiple renewable energy devices owing to the reduced amount of raw materials and increase flexibility of choosing from low-cost candidates, which translates directly into reduced capital cost. This is a key driving force to make renewable technology competitive in the energy market. This thesis is focused on the measurement of energy level alignments at interfaces of thin film structures for renewable energy applications. There are two primary foci: II -VI semiconductor ZnSe/ZnTe thin film solar cells and Bi2Te3/Sb2Te3 thin film structures for thermoelectric applications. In both cases, the electronic structure and energy band alignment at interfaces usually controls the carrier transport behavior and determines the quality of the device. High-resolution photoemission spectroscopy (lab-based XPS & synchrotron-based UPS) was used to investigate the chemical and electronic properties of epitaxial Bi2Te3 and Sb2Te3 thin films, in order to validate the anticipated band alignment at interfaces in Bi 2Te3/Sb2Te3 superlattices as one favoring electron-transmission. A simple, thorough two-step treatment of a chemical etching in dilute hydrochloric acid solution and a subsequent annealing at ˜150°C under ultra-high vacuum environment is established to remove the surface oxides completely. It is an essential step to ensure the measurements on electronic states are acquired on stoichimetric, oxide-free clean surface of Bi 2Te3 and Sb2Te3 films. The direct measurement of valence band offsets (VBO) at a real Sb 2Te3/Bi2Te3 interface is designed based on the Kraut model; a special stacking film structure is prepared intentionally: sufficiently thin Sb2Te3 film on top of Bi2Te 3 that photoelectrons from both of them are collected simultaneously. From a

  5. Comparison and optimization of randomly textured surfaces in thin-film solar cells.

    PubMed

    Rockstuhl, C; Fahr, S; Bittkau, K; Beckers, T; Carius, R; Haug, F-J; Söderström, T; Ballif, C; Lederer, F

    2010-09-13

    Using rigorous diffraction theory we investigate the scattering properties of various random textures currently used for photon management in thin-film solar cells. We relate the haze and the angularly resolved scattering function of these cells to the enhancement of light absorption. A simple criterion is derived that provides an explanation why certain textures operate more beneficially than others. Using this criterion we propose a generic surface profile that outperforms the available substrates. This work facilitates the understanding of the effect of randomly textured surfaces and provides guidelines towards their optimization.

  6. Angular response of thin-film organic solar cells with periodic metal back nanostrips.

    PubMed

    Sha, Wei E I; Choy, Wallace C H; Chew, Weng Cho

    2011-02-15

    We theoretically study the angular response of thin-film organic solar cells with periodic Au back nanostrips. In particular, the equation of the generalized Lambert's cosine law for arbitrary periodic nanostructure is formulated. We show that the periodic strip structure achieves wide-angle absorption enhancement compared with the planar nonstrip structure for both the s- and p-polarized light, which is mainly attributed to the resonant Wood's anomalies and surface plasmon resonances, respectively. The work is important for designing and optimizing high-efficiency photovoltaic cells.

  7. Enhanced light absorption in thin film silicon solar cells with Fourier-series based periodic nanostructures.

    PubMed

    Guo, Xiaowei; Wang, Dashuai; Liu, Bang; Li, Shaorong; Sheng, Xing

    2016-01-25

    We proposed a Fourier-series based periodic nanostructure(FSPN) for light trapping in thin film silicon solar cells. By globally optimizing the Fourier coefficients across entire silicon absorption spectrum, we obtained a FSPN structure with short circuit current density greater than 24 mA/cm(2) for a 1μm real silicon absorption layer. The spectral analysis shows at normal incidence the FSPN exhibits a collection effect of periodic gratings and performs over 84.6% better than random texture. The angular analysis shows that the FSPN outperforms grating and random textures within 70 °.

  8. Chemical etching of zinc oxide for thin-film silicon solar cells.

    PubMed

    Hüpkes, Jürgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

    2012-01-16

    Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided.

  9. Mode coupling by plasmonic surface scatterers in thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    van Lare, M.; Lenzmann, F.; Verschuuren, M. A.; Polman, A.

    2012-11-01

    We demonstrate effective mode coupling by light scattering from periodic Ag nanoparticle arrays printed onto a completed thin-film a-Si:H solar cell. Current-voltage measurements show a photocurrent enhancement of 10% compared to a flat reference cell with a standard antireflection coating. External quantum efficiency measurements for the nanopatterned cells show clear infrared photocurrent enhancement peaks, corresponding to coupling to discrete waveguide modes in the a-Si:H layer. The data are in good agreement with three-dimensional finite element simulations, which are used to further optimize the design. We show that broadband photocurrent enhancement can be obtained over the 450-750 nm spectral range.

  10. Self-organized broadband light trapping in thin film amorphous silicon solar cells.

    PubMed

    Martella, C; Chiappe, D; Delli Veneri, P; Mercaldo, L V; Usatii, I; Buatier de Mongeot, F

    2013-06-07

    Nanostructured glass substrates endowed with high aspect ratio one-dimensional corrugations are prepared by defocused ion beam erosion through a self-organized gold (Au) stencil mask. The shielding action of the stencil mask is amplified by co-deposition of gold atoms during ion bombardment. The resulting glass nanostructures enable broadband anti-reflection functionality and at the same time ensure a high efficiency for diffuse light scattering (Haze). It is demonstrated that the patterned glass substrates exhibit a better photon harvesting than the flat glass substrate in p-i-n type thin film a-Si:H solar cells.

  11. High photocurrent polycrystalline thin-film CdS/CuInSe2 solar cell

    NASA Astrophysics Data System (ADS)

    Mickelsen, R. A.; Chen, W. S.

    1980-03-01

    A polycrystalline thin-film CdS/CuInSe2 heterojunction solar cell with an efficiency of 5.7% has been prepared using a simultaneous elemental evaporation technique to deposit the CuInSe2 film. The cell's short-circuit current of 31 mA/sq cm under 100 mW/sq cm is the highest ever reported for a 1-sq-cm cell. Heat treatments have been found to improve cell efficiency and to also change the cell I-V and C-V characteristics.

  12. First-Principles Study of Back Contact Effects on CdTe Thin Film Solar Cells

    SciTech Connect

    Du, Mao-Hua

    2009-01-01

    Forming a chemically stable low-resistance back contact for CdTe thin-film solar cells is critically important to the cell performance. This paper reports theoretical study of the effects of the back-contact material, Sb{sub 2}Te{sub 3}, on the performance of the CdTe solar cells. First-principles calculations show that Sb impurities in p-type CdTe are donors and can diffuse with low diffusion barrier. There properties are clearly detrimental to the solar-cell performance. The Sb segregation into the grain boundaries may be required to explain the good efficiencies for the CdTe solar cells with Sb{sub 2}Te{sub 3} back contacts.

  13. Multifunctional integration of thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites

    SciTech Connect

    Jason Maung, K.; Hahn, H. Thomas; Ju, Y.S.

    2010-03-15

    Multifunction integration of solar cells in load-bearing structures can enhance overall system performance by reducing parasitic components and material redundancy. The article describes a manufacturing strategy, named the co-curing scheme, to integrate thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites and eliminate parasitic packaging layers. In this scheme, an assembly of a solar cell and a prepreg is cured to form a multifunctional composite in one processing step. The photovoltaic performance of the manufactured structures is then characterized under controlled cyclic mechanical loading. The study finds that the solar cell performance does not degrade under 0.3%-strain cyclic tension loading up to 100 cycles. Significant degradation, however, is observed when the magnitude of cyclic loading is increased to 1% strain. The present study provides an initial set of data to guide and motivate further studies of multifunctional energy harvesting structures. (author)

  14. Mixing Effect of Gold and Silver Nanoparticles on Enhancement in Performance of Organic Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Akiyama, Tsuyoshi; Yamamoto, Tomoki; Oku, Takeo; Yahiro, Masayuki; Kurihara, Takashi; Adachi, Chihaya; Yamada, Sunao

    2013-12-01

    Bulk-heterojunction organic thin-film solar cells incorporating gold and silver nanoparticles were fabricated and evaluated. These nanoparticles were embedded in the hole-transport layer of the solar cells. Plasmonic absorption peaks of isolated gold and silver nanoparticles were confirmed from extinction spectra even in the hole-transport material. The incorporation of gold and silver nanoparticles increased the photoelectric conversion efficiency of organic thin-film solar cells, whose enhancement ratio was further increased by mixing gold and silver nanoparticles.

  15. Hole-conductor-free perovskite organic lead iodide heterojunction thin-film solar cells: High efficiency and junction property

    NASA Astrophysics Data System (ADS)

    Shi, Jiangjian; Dong, Juan; Lv, Songtao; Xu, Yuzhuan; Zhu, Lifeng; Xiao, Junyan; Xu, Xin; Wu, Huijue; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2014-02-01

    Efficient hole-conductor-free organic lead iodide thin film solar cells have been fabricated with a sequential deposition method, and a highest efficiency of 10.49% has been achieved. Meanwhile, the ideal current-voltage model for a single heterojunction solar cell is applied to clarify the junction property of the cell. The model confirms that the TiO2/CH3NH3PbI3/Au cell is a typical heterojunction cell and the intrinsic parameters of the cell are comparable to that of the high-efficiency thin-film solar cells.

  16. Photonic and plasmonic structures for enhancing efficiency of thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Pattnaik, Sambit

    Crystalline silicon solar cells use high cost processing techniques as well as thick materials that are ˜ 200µm thick to convert solar energy into electricity. From a cost viewpoint, it is highly advantageous to use thin film solar cells which are generally made in the range of 0.1-3µm in thickness. Due to this low thickness, the quantity of material is greatly reduced and so is the number and complexity of steps involved to complete a device, thereby allowing a continuous processing capability improving the throughput and hence greatly decreasing the cost. This also leads to faster payback time for the end user of the photovoltaic panel. In addition, due to the low thickness and the possibility of deposition on flexible foils, the photovoltaic (PV) modules can be flexible. Such flexible PV modules are well suited for building-integrated applications and for portable, foldable, PV power products. For economical applications of solar cells, high efficiency is an important consideration. Since Si is an indirect bandgap material, a thin film of Si needs efficient light trapping to achieve high optical absorption. The previous work in this field has been mostly based on randomly textured back reflectors. In this work, we have used a novel approach, a periodic photonic and plasmonic structure, to optimize current density of the devices by absorbing longer wavelengths without hampering other properties. The two dimensional diffraction effect generated by a periodic structure with the plasmonic light concentration achieved by silver cones to efficiently propagate light in the plane at the back surface of a solar cell, achieves a significant increase in optical absorption. Using such structures, we achieved a 50%+ increase in short circuit current in a nano-crystalline (nc-Si) solar cell relative to stainless steel. In addition to nc-Si solar cells on stainless steel, we have also used the periodic photonic structure to enhance optical absorption in amorphous cells and

  17. Solar Selective Coatings Prepared From Thin-Film Molecular Mixtures and Evaluated

    NASA Technical Reports Server (NTRS)

    Jaworske, Don A.

    2003-01-01

    Thin films composed of molecular mixtures of metal and dielectric are being considered for use as solar selective coatings for a variety of space power applications. By controlling molecular mixing during ion-beam sputter deposition, researchers can tailor the solar selective coatings to have the combined properties of high solar absorptance and low infrared emittance. On orbit, these combined properties simultaneously maximize the amount of solar energy captured by the coating and minimize the amount of thermal energy radiated. The solar selective coatings are envisioned for use on minisatellites, for applications where solar energy is used to power heat engines or to heat remote regions in the interior of the spacecraft. Such systems may be useful for various missions, particularly those to middle Earth orbit. Sunlight must be concentrated by a factor of 100 or more to achieve the desired heat inlet operating temperature. At lower concentration factors, the temperature of the heat inlet surface of the heat engine is too low for efficient operation, and at high concentration factors, cavity type heat receivers become attractive. The an artist's concept of a heat engine, with the annular heat absorbing surface near the focus of the concentrator coated with a solar selective coating is shown. In this artist's concept, the heat absorbing surface powers a small Stirling convertor. The astronaut's gloved hand is provided for scale. Several thin-film molecular mixtures have been prepared and evaluated to date, including mixtures of aluminum and aluminum oxide, nickel and aluminum oxide, titanium and aluminum oxide, and platinum and aluminum oxide. For example, a 2400- Angstrom thick mixture of titanium and aluminum oxide was found to have a solar absorptance of 0.93 and an infrared emittance of 0.06. On the basis of tests performed under flowing nitrogen at temperatures as high as 680 C, the coating appeared to be durable at elevated temperatures. Additional durability

  18. Broadband absorption enhancement in plasmonic thin-film solar cells with grating surface

    NASA Astrophysics Data System (ADS)

    Liu, Li; Huo, Yiping; Zhao, Kaijun; Zhao, Ting; Li, Yuan

    2015-10-01

    The plasmonic thin-film solar cells with grating surface is structured and simulated by Comsol Multiphysics software using finite element method. The absorption efficiency of solar cells has been systemically studied by considering structure characteristic parameters. The absorption of grating surface cell is much broader and stronger than that of smooth surface on a-Si at the wavelength from 400 to 700 nm. The value of total absorption efficiency (TAE) increases from 47% to 69.3%. The embedded Ag nanoparticle array contributes to the improvement of the absorption of a-Si at longer wavelength range. The localized surface plasmon resonance is induced by Ag nanoparticles, and so that the TAE is increased to 75.1% when the radius of nanoparticle is 60 nm at the bottom of a-Si with periodic width 200 nm. The grating surface always plays a role to suppress light scattering from the active region, so more light can be absorbed again by a-Si in the infrared-region. Therefore, the results have significance in providing a theoretical foundation for the applications of thin-film solar cell.

  19. Plasmonic enhancement of thin-film solar cells using gold-black coatings

    SciTech Connect

    Fredricksen, Christopher J.; Panjwani, D. R.; Arnold, J. P.; Figueiredo, P. N.; Rezaie, F. K.; Colwell, J. E.; Baillie, K.; Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.; Peale, Robert E.

    2011-08-11

    Coatings of conducting gold-black nano-structures on commercial thin-film amorphous-silicon solar cells enhance the short-circuit current by 20% over a broad spectrum from 400 to 800 nm wavelength. The efficiency, i.e. the ratio of the maximum electrical output power to the incident solar power, is found to increase 7% for initial un-optimized coatings. Metal blacks are produced cheaply and quickly in a low-vacuum process requiring no lithographic patterning. The inherently broad particle-size distribution is responsible for the broad spectrum enhancement in comparison to what has been reported for mono-disperse lithographically deposited or self-assembled metal nano-particles. Photoemission electron microscopy reveals the spatial-spectral distribution of hot-spots for plasmon resonances, where scattering of normally-incident solar flux into the plane increases the effective optical path in the thin film to enhance light harvesting. Efficiency enhancement is correlated with percent coverage and particle size distribution, which are determined from histogram and wavelet analysis of scanning electron microscopy images. Electrodynamic simulations reveal how the gold-black particles scatter the radiation and locally enhance the field strength.

  20. Thin film polycrystalline silicon: Promise and problems in displays and solar cells

    SciTech Connect

    Fonash, S.J.

    1995-08-01

    Thin film polycrystalline Si (poly-Si) with its carrier mobilities, potentially good stability, low intragrain defect density, compatibility with silicon processing, and ease of doping activation is an interesting material for {open_quotes}macroelectronics{close_quotes} applications such as TFTs for displays and solar cells. The poly-Si films needed for these applications can be ultra-thin-in the 500{Angstrom} to 1000{Angstrom} thickness range for flat panel display TFTs and in the 4{mu}m to 10{mu}m thickness range for solar cells. Because the films needed for these microelectronics applications can be so thin, an effective approach to producing the films is that of crystallizing a-Si precursor material. Unlike cast materials, poly-Si films made this way can be produced using low temperature processing. Unlike deposited poly-Si films, these crystallized poly-Si films can have grain widths that are much larger than the film thickness and almost atomically smooth surfaces. This thin film poly-Si crystallized from a-Si precursor films, and its promise and problems for TFTs and solar cells, is the focus of this discussion.

  1. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Lipovšek, Benjamin; Krč, Janez; Isabella, Olindo; Zeman, Miro; Topič, Marko

    2010-11-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-film solar cells. The parameters of white paint, such as the paint film thickness, the pigment volume concentration (PVC), and the pigment/binder refractive index ratio (RIR), are examined and optimized to achieve the required optical properties for back reflector application. The simulation trends indicate that white paint back reflectors with sufficient film thickness and higher PVC and RIR values exhibit improved reflectivity characteristics which results in an increased long-wavelength quantum efficiency of thin-film silicon solar cells. The simulation results based on the 1D model agree very well with the experimental data obtained from reflectance measurements of various white paint compositions and quantum efficiency measurements of amorphous silicon solar cells with white paint back reflectors.

  2. Perovskite/germanium tandem: A potential high efficiency thin film solar cell design

    NASA Astrophysics Data System (ADS)

    Zi, Wei; Ren, Xiaodong; Ren, Xianpei; Wei, Qinbo; Gao, Fei; Liu, Shengzhong Frank

    2016-12-01

    Perovskite absorbs from ultraviolet (UV) to ∼800 nm, and germanium covers to 1800 nm, the combination shows excellent match in terms of solar spectrum-splitting. The optical properties of CH3NH3PbI3-xClx perovskite and single-crystalline germanium (c-Ge) tandem solar cell on a special designed substrate with triangular grating are analyzed and discussed. The finite difference time domain (FDTD) approach is used to solve the Maxwell's equations in three dimensions rigorously. By optimizing the absorption layer thickness, the current match between the top and the bottom component cells is achieved using very thin films as thin as 1500 nm. By controlling the thickness of perovskite and c-Ge to 750 nm each, high short circuit current density (Jsc) of the tandem solar cell is achieved to as high as 23.70 mA/cm2. The perovskite/c-Ge tandem thin film cell design is capable of a potential efficiency 24.88% based on the simulation.

  3. Novel concepts for low-cost and high-efficient thin film solar cells

    NASA Astrophysics Data System (ADS)

    Gómez, D.; Menéndez, A.; Sánchez, P.; Martínez, A.; Andrés, L. J.; Menéndez, M. F.; Campos, N.; García, A.; Sánchez, B.

    2011-09-01

    This work presents the activities carried out at ITMA Materials Technology related to the building integration of thin film (TF) photovoltaics (PV). Three different approaches have been developed in order to achieve high efficient solar cells at low manufacturing costs: (i) a new route for manufacturing monolithical silicon based thin film solar cells on building materials, (ii) the use of metallic nanoparticles for light trapping (plasmonic effects and light scattering) and (iii) the luminescent sol-gel coating on glass for solar concentration. In the first case, amorphous silicon modules (single junction) have been successfully manufactured at lab scale on steel and commercial ceramic substrates with efficiencies of 5.4% and 4.0%, respectively. Promising initial attempts have been also made in ethylene tetrafluoroethylene (ETFE), a polymer with high potential in textile architecture. In a similar way, the development of nanotechnology based coatings (metallic nanoparticles and luminescent materials) represent the most innovative part of the work and some preliminary results are showed.

  4. P-doped strontium titanate grown using two target pulsed laser deposition for thin film solar cells

    NASA Astrophysics Data System (ADS)

    Man, Hamdi

    Thin-film solar cells made of Mg-doped SrTiO3 p-type absorbers are promising candidates for clean energy generation. This material shows p-type conductivity and also demonstrates reasonable absorption of light. In addition, p-type SrTiO3 can be deposited as thin films so that the cost can be lower than the competing methods. In this work, Mg-doped SrTiO3 (STO) thin-films were synthesized and analyzed in order to observe their potential to be employed as the base semiconductor in photovoltaic applications. Mg-doped STO thin-films were grown by using pulsed laser deposition (PLD) using a frequency quadrupled Yttrium Aluminum Garnet (YAG) laser and with a substrate that was heated by back surface absorption of infrared (IR) laser light. The samples were characterized using X-ray photoelectron spectroscopy (XPS) and it was observed that Mg atoms were doped successfully in the stoichiometry. Reflection high energy electron diffraction (RHEED) spectroscopy proved that the thin films were polycrystalline. Kelvin Probe work function measurements indicated that the work function of the films were 4.167 eV after annealing. UV/Vis Reflection spectroscopy showed that Mg-doped STO thin-films do not reflect significantly except in the ultraviolet region of the spectrum where the reflection percentage increased up to 80%. Self-doped STO thin-films, Indium Tin Oxide (ITO) thin films and stainless steel foil (SSF) were studied in order to observe their characteristics before employing them in Mg-doped STO based solar cells. Self-doped STO thin films were grown using PLD and the results showed that they are capable of serving as the n-type semiconductor in solar cell applications with oxygen vacancies in their structure and low reflectivity. Indium Tin Oxide thin-films grown by PLD system showed low 25-50 ?/square sheet resistance and very low reflection features. Finally, commercially available stainless steel foil substrates were excellent substrates for the inexpensive growth of

  5. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    PubMed

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  6. A two-layer structured PbI2 thin film for efficient planar perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Ying, Chao; Shi, Chengwu; Wu, Ni; Zhang, Jincheng; Wang, Mao

    2015-07-01

    In this paper, a two-layer structured PbI2 thin film was constructed by the spin-coating procedure using a 0.80 M PbI2 solution in DMF and subsequent close-spaced vacuum thermal evaporation using PbI2 powder as a source. The bottom PbI2 thin film was compact with a sheet-like appearance, parallel to the FTO substrate, and can be easily converted to a compact perovskite thin film to suppress the charge recombination of the electrons of the TiO2 conduction band and the holes of the spiro-OMeTAD valence band. The top PbI2 thin film was porous with nano-sheet arrays, perpendicular to the FTO substrate, and can be easily converted to a porous perovskite thin film to improve the hole migration from the perovskite to spiro-OMeTAD and the charge separation at the perovskite/spiro-OMeTAD interface. The planar perovskite solar cells based on the two-layer structured PbI2 thin film exhibited a photoelectric conversion efficiency of 11.64%, along with an open-circuit voltage of 0.90 V, a short-circuit photocurrent density of 19.29 mA cm-2 and a fill factor of 0.67.

  7. A two-layer structured PbI2 thin film for efficient planar perovskite solar cells.

    PubMed

    Ying, Chao; Shi, Chengwu; Wu, Ni; Zhang, Jincheng; Wang, Mao

    2015-07-28

    In this paper, a two-layer structured PbI2 thin film was constructed by the spin-coating procedure using a 0.80 M PbI2 solution in DMF and subsequent close-spaced vacuum thermal evaporation using PbI2 powder as a source. The bottom PbI2 thin film was compact with a sheet-like appearance, parallel to the FTO substrate, and can be easily converted to a compact perovskite thin film to suppress the charge recombination of the electrons of the TiO2 conduction band and the holes of the spiro-OMeTAD valence band. The top PbI2 thin film was porous with nano-sheet arrays, perpendicular to the FTO substrate, and can be easily converted to a porous perovskite thin film to improve the hole migration from the perovskite to spiro-OMeTAD and the charge separation at the perovskite/spiro-OMeTAD interface. The planar perovskite solar cells based on the two-layer structured PbI2 thin film exhibited a photoelectric conversion efficiency of 11.64%, along with an open-circuit voltage of 0.90 V, a short-circuit photocurrent density of 19.29 mA cm(-2) and a fill factor of 0.67.

  8. A computational study on the energy bandgap engineering in performance enhancement of CdTe thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Ameen M.; Rahman, K. S.; Ali, Lamya M.; Akhtaruzzaman, M.; Sopian, K.; Radiman, S.; Amin, N.

    In this study, photovoltaic properties of CdTe thin film in the configuration of n-SnO2/n-CdS/p-CdTe/p-CdTe:Te/metal have been studied by numerical simulation software named ;Analysis of Microelectronic and Photonic Structure; (AMPS-1D). A modified structure for CdTe thin film solar cell has been proposed by numerical analysis with the insertion of a back contact buffer layer (CdTe:Te). This layer can serve as a barrier that will decelerate the copper diffusion in CdTe solar cell. Four estimated energy bandgap relations versus the Tellurium (Te) concentrations and the (CdTe:Te) layer thickness have been examined thoroughly during simulation. Correlation between energy bandgap with the CdTe thin film solar cell performance has also been established.

  9. Enhancement of optical absorption in thin-film solar cells through the excitation of higher-order nanoparticle plasmon modes.

    PubMed

    Akimov, Yu A; Koh, W S; Ostrikov, K

    2009-06-08

    Recent research in the rapidly emerging field of plasmonics has shown the potential to significantly enhance light trapping inside thin-film solar cells by using metallic nanoparticles. In this article it is demonstrated the plasmon enhancement of optical absorption in amorphous silicon solar cells by using silver nanoparticles. Based on the analysis of the higher-order surface plasmon modes, it is shown how spectral positions of the surface plasmons affect the plasmonic enhancement of thin-film solar cells. By using the predictive 3D modeling, we investigate the effect of the higher-order modes on that enhancement. Finally, we suggest how to maximize the light trapping and optical absorption in the thin-film cell by optimizing the nanoparticle array parameters, which in turn can be used to fine tune the corresponding surface plasmon modes.

  10. Transparent conducting oxide contacts and textured metal back reflectors for thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Franken, R. H.-J.

    2006-09-01

    With the growing population and the increasing environmental problems of the 'common' fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic (PV) systems, can play a major role in the urgently needed energy transition in electricity production. At the present time PV module production is dominated by the crystalline wafer technology. Thin film silicon technology is an alternative solar energy technology that operates at lower efficiencies, however, it has several significant advantages, such as the possibility of deposition on cheap (flexible) substrates and the much smaller silicon material consumption. Because of the small thickness of the solar cells, light trapping schemes are needed in order to obtain enough light absorption and current generation. This thesis describes the research on thin film silicon solar cells with the focus on the optimization of the transparent conducting oxide (TCO) layers and textured metal Ag substrate layers for the use as enhanced light scattering back reflectors in n-i-p type of solar cells. First we analyzed ZnO:Al (TCO) layers deposited in an radio frequent (rf) magnetron deposition system equipped with a 7 inch target. We have focused on the improvement of the electrical properties without sacrificing the optical properties by increasing the mobility and decreasing the grain boundary density. Furthermore, we described some of the effects on light trapping of ZnO:Al enhanced back reflectors. The described effects are able to explain the observed experimental data. Furthermore, we present a relation between the surface morphology of the Ag back contact and the current enhancement in microcrystalline (muc-Si:H) solar cells. We show the importance of the lateral feature sizes of the Ag surface on the light scattering and introduce a method to characterize the quality of the back reflector by combining the vertical and lateral feature sizes

  11. Improving the efficiency of thin film tandem solar cells by plasmonic intermediate reflectors

    NASA Astrophysics Data System (ADS)

    Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

    2010-09-01

    Thin film tandem solar cells made of amorphous and microcrystalline silicon provide renewable energy at the benefit of low material consumption. As a drawback, these materials do not posses the high carrier mobilities of their crystalline counterpart which limits the feasible material thickness. For maintaining the light absorption as high as possible, photon management is required. Here we show that metallic nanodiscs that sustain localized plasmon polaritons can increase the efficiency of such solar cells if they are incorporated into the dielectric intermediate reflector separating the top and the bottom cell. We provide quantitative estimates for the possible absorption enhancement of optimized bi-periodic nanodiscs that are feasible for fabrication. Emphasis is also put on discussing the impact of obliquely incident sun light on the solar cell performance.

  12. Research on the optimum hydrogenated silicon thin films for application in solar cells

    NASA Astrophysics Data System (ADS)

    Lei, Qing-Song; Wu, Zhi-Meng; Geng, Xin-Hua; Zhao, Ying; Sun, Jian; Xi, Jian-Ping

    2006-12-01

    Hydrogenated silicon (Si:H) thin films for application in solar cells were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 oC. The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage (I-V) characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

  13. Enhancing the absorption capabilities of thin-film solar cells using sandwiched light trapping structures.

    PubMed

    Abdellatif, S; Kirah, K; Ghannam, R; Khalil, A S G; Anis, W

    2015-06-10

    A novel structure for thin-film solar cells is simulated with the purpose of maximizing the absorption of light in the active layer and of reducing the parasitic absorption in other layers. In the proposed structure, the active layer is formed from an amorphous silicon thin film sandwiched between silicon nanowires from above and photonic crystal structures from below. The upper electrical contact consists of an indium tin oxide layer, which serves also as an antireflection coating. A metal backreflector works additionally as the other contact. The simulation was done using a new reliable, efficient and generic optoelectronic approach. The suggested multiscale simulation model integrates the finite-difference time-domain algorithm used in solving Maxwell's equation in three dimensions with a commercial simulation platform based on the finite element method for carrier transport modeling. The absorption profile, the external quantum efficient, and the power conversion efficiency of the suggested solar cell are calculated. A noticeable enhancement is found in all the characteristics of the novel structure with an estimated 32% increase in the total conversion efficiency over a cell without any light trapping mechanisms.

  14. 14% sputtered thin-film solar cells based on CdTe

    NASA Astrophysics Data System (ADS)

    Compaan, A. D.; Gupta, A.; Drayton, J.; Lee, S.-H.; Wang, S.

    2004-02-01

    Polycrystalline II-VI semiconductor materials show great promise for thin-film photovoltaic cells and modules. Large-area deposition of these II-VI semiconductors such as CdTe is possible by a variety of methods but the use of a plasma-based method such as magnetron sputtering can have significant advantages. Here we present recent results in the fabrication of CdS/CdTe cells using rf magnetron sputtering and discuss some of the advantages that appear possible from the use of sputtering methods in this class of materials. Some of these advantages are particularly relevant as the polycrystalline thin-film PV community addresses issues related to the challenges of fabricating high efficiency tandem cells with efficiencies over 25%. Our best results have been obtained with sputtered ZnO:Al to achieve a CdTe solar cell with 14.0% efficiency at one sun for an air-mass-1.5 global spectrum. In addition, we have studied reactive sputtering of ZnTe:N which shows promise for use as a transparent back contact or recombination junction for alloyed II-VI-based top cells in a tandem solar-cell configuration.

  15. ZnO transparent conductive oxide for thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Söderström, T.; Dominé, D.; Feltrin, A.; Despeisse, M.; Meillaud, F.; Bugnon, G.; Boccard, M.; Cuony, P.; Haug, F.-J.; Faÿ, S.; Nicolay, S.; Ballif, C.

    2010-03-01

    There is general agreement that the future production of electric energy has to be renewable and sustainable in the long term. Photovoltaic (PV) is booming with more than 7GW produced in 2008 and will therefore play an important role in the future electricity supply mix. Currently, crystalline silicon (c-Si) dominates the market with a share of about 90%. Reducing the cost per watt peak and energy pay back time of PV was the major concern of the last decade and remains the main challenge today. For that, thin film silicon solar cells has a strong potential because it allies the strength of c-Si (i.e. durability, abundancy, non toxicity) together with reduced material usage, lower temperature processes and monolithic interconnection. One of the technological key points is the transparent conductive oxide (TCO) used for front contact, barrier layer or intermediate reflector. In this paper, we report on the versatility of ZnO grown by low pressure chemical vapor deposition (ZnO LP-CVD) and its application in thin film silicon solar cells. In particular, we focus on the transparency, the morphology of the textured surface and its effects on the light in-coupling for micromorph tandem cells in both the substrate (n-i-p) and superstrate (p-i-n) configurations. The stabilized efficiencies achieved in Neuchâtel are 11.2% and 9.8% for p-i-n (without ARC) and n-i-p (plastic substrate), respectively.

  16. Ultimate form freedom in thin film solar cells by postmanufacture laser-based processing

    NASA Astrophysics Data System (ADS)

    Gilot, Jan; Emelin, Baptiste; Galagan, Yulia; Mandamparambil, Rajesh; Andriessen, Ronn

    2015-01-01

    Thin film photovoltaics can be beneficial for specific applications like building integrated photovoltaics. To fully exploit the differentiator of form freedom, the interconnections in thin film modules can be tuned depending on the required module output. Traditionally, an alternation of coating and scribing steps is applied, determining the form from the start. Here, we present a set of techniques to define the module design from a master substrate with homogeneously coated electroactive layers. By applying subtractive and additive laser-based processes, the size and form of the module are only fixed after the manufacturing of the whole solar cell stack. By laser-induced forward transfer, an isolating dielectric material and a conductive top electrode are deposited in laser ablated scribes to enable the interconnection between two adjacent cells. After optimization of the laser settings for ablation and forward transfer, the optimal annealing time and temperature for the curing of the silver top electrode were determined. The proof of principle was demonstrated by constructing a 4-cell organic solar module of 1.0% efficiency on an area of over 3 cm2 showing the anticipated short-circuit current and open-circuit voltage.

  17. Characteristics of Sputtered ZnO Thin Films for an Inverted Organic Solar Cell.

    PubMed

    Park, Yong Seob; Park, Chul Min; Lee, Jaehyeong

    2016-05-01

    Several research groups have claimed high energy conversion efficiency in organic solar cells. However, it still has low efficiency and is unstable, because organic materials are easily oxidized by atmospheric humidity and UV light. In this work, ZnO thin film as the blocking layer attributed to the interference of the injection of the hole from the P3HT and no charge carrier recombination. We obtained the maximum power conversion efficiency of 1.9% under AM 1.5 G spectral illumination of 100 MWcm(-2), when we used a ZnO film of 60 nm and the optimized P3HT:PCBM, and Au as the back electrode to solve the reaction problem of Al electrode and to control the work function between the HOMO level of P3HT and the energy level of the metal electrode. Power conversion efficiency of inverted organic solar cell (IOSC) is significantly dependent on the thickness of the ZnO thin film deposited by unbalanced magnetron sputtering method. Also, the stability of IOSC is measured under ambient conditions.

  18. Thin film solar cells with Si nanocrystallites embedded in amorphous intrinsic layers by hot-wire chemical vapor deposition.

    PubMed

    Park, Seungil; Parida, Bhaskar; Kim, Keunjoo

    2013-05-01

    We investigated the thin film growths of hydrogenated silicon by hot-wire chemical vapor deposition with different flow rates of SiH4 and H2 mixture ambient and fabricated thin film solar cells by implementing the intrinsic layers to SiC/Si heterojunction p-i-n structures. The film samples showed the different infrared absorption spectra of 2,000 and 2,100 cm(-1), which are corresponding to the chemical bonds of SiH and SiH2, respectively. The a-Si:H sample with the relatively high silane concentration provides the absorption peak of SiH bond, but the microc-Si:H sample with the relatively low silane concentration provides the absorption peak of SiH2 bond as well as SiH bond. Furthermore, the microc-Si:H sample showed the Raman spectral shift of 520 cm(-1) for crystalline phase Si bonds as well as the 480 cm(-1) for the amorphous phase Si bonds. These bonding structures are very consistent with the further analysis of the long-wavelength photoconduction tail and the formation of nanocrystalline Si structures. The microc-Si:H thin film solar cell has the photovoltaic behavior of open circuit voltage similar to crystalline silicon thin film solar cell, indicating that microc-Si:H thin film with the mixed phase of amorphous and nanocrystalline structures show the carrier transportation through the channel of nanocrystallites.

  19. Roles of Fullerene-Based Interlayers in Enhancing the Performance of Organometal Perovskite Thin-Film Solar Cells

    DOE PAGES

    Liang, Po-Wei; Chueh, Chu-Chen; Williams, Spencer T.; ...

    2015-02-27

    Roles of fullerene-based interlayers in enhancing the performance of organometal perovskite thin-film solar cells are elucidated. By studying various fullerenes, a clear correlation between the electron mobility of fullerenes and the resulting performance of derived devices is determined. The metallic characteristics of the bilayer perovskite/fullerene field-effect transistor indicates an effective charge redistribution occurring at the corresponding interface. Lastly, a conventional perovskite thin-film solar cell derived from the C60 electron-transporting layer (ETL) affords a high power conversion efficiency of 15.4%.

  20. Roles of Fullerene-Based Interlayers in Enhancing the Performance of Organometal Perovskite Thin-Film Solar Cells

    SciTech Connect

    Liang, Po-Wei; Chueh, Chu-Chen; Williams, Spencer T.; Jen, Alex K. -Y.

    2015-02-27

    Roles of fullerene-based interlayers in enhancing the performance of organometal perovskite thin-film solar cells are elucidated. By studying various fullerenes, a clear correlation between the electron mobility of fullerenes and the resulting performance of derived devices is determined. The metallic characteristics of the bilayer perovskite/fullerene field-effect transistor indicates an effective charge redistribution occurring at the corresponding interface. Lastly, a conventional perovskite thin-film solar cell derived from the C60 electron-transporting layer (ETL) affords a high power conversion efficiency of 15.4%.

  1. Recrystallized thin-film silicon solar cell on graphite substrate with laser single side contact and hydrogen passivation

    NASA Astrophysics Data System (ADS)

    Li, Da; Wittmann, Stephan; Kunz, Thomas; Ahmad, Taimoor; Gawehns, Nidia; Hessmann, Maik T.; Ebser, Jan; Terheiden, Barbara; Auer, Richard; Brabec, Christoph J.

    2015-05-01

    Laser single side contact formation (LSSC) and the hydrogen passivation process are studied and developed for crystalline silicon thin film (CSiTF) solar cells on graphite substrates. The results demonstrate that these two methods can improve cell performance by increasing the open circuit voltage and fill factor. In comparison with our previous work, we have achieved an increase of 3.4% absolute cell efficiency for a 40 μm thick 4 cm2 aperture area silicon thin film solar cell on graphite substrate. Current density-voltage (J-V) measurement, quantum efficiency (QE) and light beam induced current (LBiC) are used as characterization methods.

  2. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    NASA Astrophysics Data System (ADS)

    de Jong, M. M.

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a wide range of applications, such as in green house, lighting etc, are applied in these solar cells for light trapping. Thin silicon films can be produced by decomposing silane gas, using a plasma process. In these types of processes, the temperature of the growing surface has a large influence on the quality of the grown films. Because plastic substrates limit the maximum tolerable substrate temperature, new methods have to be developed to produce device-grade silicon layers. At low temperature, polysilanes can form in the plasma, eventually forming dust particles, which can deteriorate device performance. By studying the spatially resolved optical emission from the plasma between the electrodes, we can identify whether we have a dusty plasma. Furthermore, we found an explanation for the temperature dependence of dust formation; Monitoring the formation of polysilanes as a function of temperature using a mass-spectrometer, we observed that the polymerization rate is indeed influenced by the substrate temperature. For solar cell substrate material, our choice was polycarbonate (PC), because of its low cost, its excellent transparency and its relatively high glass transition temperature of 130-140°C. At 130°C we searched for deposition recipes for device quality silicon, using a very high frequency plasma enhanced chemical deposition process. By diluting the feedstock silane with hydrogen gas, the silicon quality can be improved for amorphous silicon (a-Si), until we reach the

  3. Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

    DOE PAGES

    Xiao, Zhengguo; Yuan, Yongbo; Wang, Qi; ...

    2016-02-19

    Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From “dye” in dye sensitized solar cells to “hole conductors” and “electron conductors” in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Gratzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after themore » demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH3NH3PbI3 (MAPbI3) polycrystalline thin films. Here, this review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically impact device efficiency in the OTP thin film devices; 5) photocurrent hysteresis; 6) tandem solar cells; 7) stability of the perovskite materials and solar cell devices.« less

  4. Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

    SciTech Connect

    Xiao, Zhengguo; Yuan, Yongbo; Wang, Qi; Shao, Yuchuan; Bai, Yang; Deng, Yehao; Dong, Qingfeng; Hu, Miao; Bi, Cheng; Huang, Jinsong

    2016-02-19

    Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From “dye” in dye sensitized solar cells to “hole conductors” and “electron conductors” in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Gratzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after the demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH3NH3PbI3 (MAPbI3) polycrystalline thin films. Here, this review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically impact device efficiency in the OTP thin film devices; 5) photocurrent hysteresis; 6) tandem solar cells; 7) stability of the perovskite materials and solar cell devices.

  5. Post-growth process for flexible CdS/CdTe thin film solar cells with high specific power.

    PubMed

    Cho, Eunwoo; Kang, Yoonmook; Kim, Donghwan; Kim, Jihyun

    2016-05-16

    We demonstrated a flexible CdS/CdTe thin film solar cell with high specific power of approximately 254 W/kg. A flexible and ultra-light weight CdS/CdTe cell treated with pre-NP etch process exhibited high conversion efficiency of 13.56% in superstrate configuration. Morphological, structural and optical changes of CdS/CdTe thin films were characterized when pre-NP etch step was incorporated to the conventional post-deposition process. Improvement of photovoltaic parameters can be attributed to the removal of the oxide and the formation of Te-rich layer, which benefit the activation process. Pre-NP etched cell maintained their flexibility and performance under the repeated tensile strain of 0.13%. Our method can pave a way for manufacturing flexible CdS/CdTe thin film solar cells with high specific power for mobile and aerospace applications.

  6. Alkali-templated surface nanopatterning of chalcogenide thin films: a novel approach toward solar cells with enhanced efficiency.

    PubMed

    Reinhard, Patrick; Bissig, Benjamin; Pianezzi, Fabian; Hagendorfer, Harald; Sozzi, Giovanna; Menozzi, Roberto; Gretener, Christina; Nishiwaki, Shiro; Buecheler, Stephan; Tiwari, Ayodhya N

    2015-05-13

    Concepts of localized contacts and junctions through surface passivation layers are already advantageously applied in Si wafer-based photovoltaic technologies. For Cu(In,Ga)Se2 thin film solar cells, such concepts are generally not applied, especially at the heterojunction, because of the lack of a simple method yielding features with the required size and distribution. Here, we show a novel, innovative surface nanopatterning approach to form homogeneously distributed nanostructures (<30 nm) on the faceted, rough surface of polycrystalline chalcogenide thin films. The method, based on selective dissolution of self-assembled and well-defined alkali condensates in water, opens up new research opportunities toward development of thin film solar cells with enhanced efficiency.

  7. A study of shape optimization on the metallic nanoparticles for thin-film solar cells.

    PubMed

    Zhou, Shiwei; Huang, Xiaodong; Li, Qing; Xie, Yi Min

    2013-10-29

    The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm2. Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions.

  8. Geometrical shape design of nanophotonic surfaces for thin film solar cells.

    PubMed

    Nam, W I; Yoo, Y J; Song, Y M

    2016-07-11

    We present the effect of geometrical parameters, particularly shape, on optical absorption enhancement for thin film solar cells based on crystalline silicon (c-Si) and gallium arsenide (GaAs) using a rigorous coupled wave analysis (RCWA) method. It is discovered that the "sweet spot" that maximizes efficiency of solar cells exists for the design of nanophotonic surfaces. For the case of ultrathin, rod array is practical due to the effective optical resonances resulted from the optimum geometry whereas parabola array is viable for relatively thicker cells owing to the effective graded index profile. A specific value of thickness, which is the median value of other two devices tailored by rod and paraboloid, is optimized by truncated shape structure. It is therefore worth scanning the optimum shape of nanostructures in a given thickness in order to achieve high performance.

  9. Concepts for thin-film GaAs concentrator cells. [for solar photovoltaic space power systems

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Gale, R. P.; Mcclelland, R.; King, B.; Dingle, J.

    1989-01-01

    The development of advanced GaAs concentrator solar cells, and in particular, the use of CLEFT (cleavage of lateral epitaxial films for transfer) processes for formation of thin-film structures is reported. The use of CLEFT has made possible processing of the back, and cells with back surface grids are discussed. Data on patterned junction development are presented; such junctions are expected to be useful in back surface applications requiring point contacts, grating structures, and interdigitated back contacts. CLEFT concentrator solar cells with grids on the front and back surfaces are reported here; these cells are 4 microns thick and are bonded to glass covers for support. Air mass zero efficiency of 18.8 percent has been obtained for a CLEFT concentrator operating at 18.5 suns.

  10. A study of shape optimization on the metallic nanoparticles for thin-film solar cells

    PubMed Central

    2013-01-01

    The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm2. Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions. PMID:24168131

  11. Design principles for plasmonic thin film GaAs solar cells with high absorption enhancement

    NASA Astrophysics Data System (ADS)

    Hong, Lei; Rusli; Wang, Xincai; Zheng, Hongyu; He, Lining; Xu, Xiaoyan; Wang, Hao; Yu, HongYu

    2012-09-01

    In this paper, a systematic design and analysis of gallium arsenide thin film solar cells incorporated with a periodic silver nanoparticles (NPs) structure to enhance light absorption is presented using the finite element method. The influence of the silver nanoparticles diameter and structure periodicity on light absorption has been examined. It is found that the absorption is significantly enhanced due to the surface plasmon induced by the silver nanoparticles. The optimal structural parameters are achieved when the diameter of the nanoparticles is 200 nm and the periodicity is 444 nm. This gives rise to a maximum ultimate photocurrent of 26.32 mA/cm2 under AM1.5G solar irradiation. In addition, the underlying physics that accounts for the enhancement is discussed.

  12. Thin film solar cell design based on photonic crystal and diffractive grating structures.

    PubMed

    Mutitu, James G; Shi, Shouyuan; Chen, Caihua; Creazzo, Timothy; Barnett, Allen; Honsberg, Christiana; Prather, Dennis W

    2008-09-15

    In this paper we present novel light trapping designs applied to multiple junction thin film solar cells. The new designs incorporate one dimensional photonic crystals as band pass filters that reflect short light wavelengths (400 - 867 nm) and transmit longer wavelengths(867 -1800 nm) at the interface between two adjacent cells. In addition, nano structured diffractive gratings that cut into the photonic crystal layers are incorporated to redirect incoming waves and hence increase the optical path length of light within the solar cells. Two designs based on the nano structured gratings that have been realized using the scattering matrix and particle swarm optimization methods are presented. We also show preliminary fabrication results of the proposed devices.

  13. Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

    SciTech Connect

    Shao, Guojian; Lou, Chaogang; Kang, Jian; Zhang, Hao

    2015-12-21

    Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluate roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency.

  14. Temperature dependent electrical characterization of thin film Cu2ZnSnSe4 solar cells

    NASA Astrophysics Data System (ADS)

    Kask, E.; Krustok, J.; Giraldo, S.; Neuschitzer, M.; López-Marino, S.; Saucedo, E.

    2016-03-01

    Impedance spectroscopy (IS) and current-voltage characteristics measurements were applied to study properties of a Cu2ZnSnSe4 (CZTSe) thin film solar cell. IS measurements were done in the frequency range 20 Hz to 10 MHz. The measurement temperature was varied from 10 K to 325 K with a step ▵T  =  5 K. Temperature dependence of V oc revealed an activation energy of 962 meV, which is in the vicinity of the band gap energy of CZTSe and hence the dominating recombination mechanism in this solar cell is bulk recombination. Different temperature ranges, where electrical properties change, were found. Interface states at grain boundaries with different properties were revealed to play an important role in impedance measurements. These states can be described by introducing a constant phase element in the equivalent circuit.

  15. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    NASA Astrophysics Data System (ADS)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  16. Identification and Analysis of Distinct Features in Imaging Thin-Film Solar Cells: Preprint

    SciTech Connect

    Zaunbrecher, K. N.; Johnston, S. W.; Sites, J. R.

    2012-06-01

    Electroluminescence and photoluminescence (EL and PL) are two imaging techniques employed at NREL that are used to qualitatively evaluate solar cells. In this work, imaging lab-scale CdTe and CIGS devices provides information about small-area PV response, which will aid in determining the effects of non-uniformities on cell performance. EL, PL, and dark lock-in thermography signatures are first catalogued. Their responses to varying conditions are then studied. Further analysis includes acquiring spectral data, making microscopy measurements, and correlating luminescence to device performance. The goal of this work is to quantitatively determine non-uniformity effects on cell performance using rapid imaging techniques.

  17. Approaches to encapsulation of flexible CIGS cells

    NASA Astrophysics Data System (ADS)

    Olsen, L. C.; Gross, M. E.; Graff, G. L.; Kundu, S. N.; Chu, Xi; Lin, Steve

    2008-08-01

    Thin-film solar cells based on CIGS are being considered for large scale power plants as well as building integrated photovoltaic (BIPV) applications. Past studies indicate that CIGS cells degrade rapidly when exposed to moisture. As a result, an effective approach to encapsulation is required for CIGS cells to satisfy the international standard IEC 61646. CIGS modules fabricated for use in large power plants can be encapsulated with glass sheets on the top and bottom surfaces and can be effectively sealed around the edges. In the case of BIPV applications, however, it is desirable to utilize CIGS cells grown on flexible substrates, both for purposes of achieving reduced weight and for cases involving non-flat surfaces. For these cases, approaches to encapsulation must be compatible with the flexible substrate requirement. Even in the case of large power plants, the glass-to-glass approach to encapsulation may eventually be considered too costly. We are investigating encapsulation of flexible CIGS cells by lamination. Sheets of PET or PEN coated with multilayer barrier coatings are used to laminate the flexible cells. Results are discussed for laminated cells from two CIGS manufacturers. In both cases, the cell efficiency decreases less than 10% after 1000 hours of exposure to an environment of 85°C/85%RH. This paper discusses these two approaches, and reviews results for uncoated cells and mini-modules fabricated by the former Shell Solar Industries (SSI).

  18. Light trapping in thin film solar cells using photonic engineering device concepts

    NASA Astrophysics Data System (ADS)

    Mutitu, James Gichuhi

    In this era of uncertainty concerning future energy solutions, strong reservations have arisen over the continued use and pursuit of fossil fuels and other conventional sources of energy. Moreover, there is currently a strong and global push for the implementation of stringent measures, in order to reduce the amount of green house gases emitted by every nation. As a consequence, there has emerged a sudden and frantic rush for new renewable energy solutions. In this world of renewable energy technologies is where we find photovoltaic (PV) technology today. However, as is, there are still many issues that need to be addressed before solar energy technologies become economically viable and available to all people, in every part of the world. This renewed interest in the development of solar electricity, has led to the advancement of new avenues that address the issues of cost and efficiency associated with PV. To this end, one of the prominent approaches being explored is thin film solar cell (TFSC) technology, which offers prospects of lower material costs and enables larger units of manufacture than conventional wafer based technology. However, TFSC technologies suffer from one major problem; they have lower efficiencies than conventional wafer based solar cell technologies. This lesser efficiency is based on a number of reasons, one of which is that with less material, there is less volume for the absorption of incident photons. This shortcoming leads to the need for optical light trapping; which is concerned with admitting the maximum amount of light into the solar cell and keeping the light within the structure for as long as possible. In this thesis, I present the fundamental scientific ideas, practice and methodology behind the application of photonic engineering device concepts to increase the light trapping capacity of thin film solar cells. In the introductory chapters, I develop the basic ideas behind light trapping in a sequential manner, where the effects

  19. Polypyrrole thin films decorated with copper nanostructures as counter electrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ghani, Sheeba; Sharif, Rehana; Bashir, Saima; Zaidi, Azhar A.; Rafique, M. S.; Ashraf, Ayesha; Shahzadi, Shamaila; Rafique, Shaista; Kamboh, Afzal H.

    2015-05-01

    A two-step electrochemical polymerization method for the fabrication of polypyrrole (PPY) thin films decorated with copper nanostructures on a stainless steel has been employed. The PPY film thickness affects the size, shape, and the number density of the copper nanostructures and provides an easy approach to control the morphology of these nanostructures. SEM images show nanorod like structures of copper on 200 nm PPY film. By employing this composite film as counter electrode (CE), a dye-sensitized solar cell (DSSC) achieves a conversion efficiency of 7.42%, which is greater than Pt CE based DSSC (5.63%). The superior photovoltaic efficiency for the Cu-PPY film is attributed to unique porous PPY thin film and copper nanorods structure that leads to higher cathodic current density (5.38 mA/cm2), large electrocatalytic activity, and small charge transfer resistance(1.92 Ω cm-2). Therefore, Cu-PPY composite can be considered a competitive and promising CE material with the traditional and expensive Pt CE, for large-scale DSSCs production.

  20. Three dimensionally structured interdigitated back contact thin film heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Hangarter, C. M.; Hamadani, B. H.; Guyer, J. E.; Xu, H.; Need, R.; Josell, D.

    2011-04-01

    Three dimensionally structured thin film photovoltaic devices based on interdigitated arrays of microscale electrodes are examined by external quantum efficiency simulations, indicating considerable JSC enhancement is possible through elimination of the front contact and window layer required in planar geometry devices. Electrode parameters including, pitch, width, height, and material are modeled and experimentally probed, demonstrating experimentally and capturing in models dependence on intrinsic material properties and electrode dimensions. In contrast to analogous silicon wafer back contact solar cells where the electrodes are placed on the silicon absorber at the end of processing, in this design the semiconductor is deposited on the electrodes, taking advantage of the thin film processing already required. Electrodeposited CdS/CdTe heterojunction devices approach 1% efficiencies with simulations as well as optical measurements indicating significant potential for improvement. Suboptimal performance is attributed to unintended materials reactions that preclude annealing at the temperatures required for absorber optimization as well as the Schottky barrier formation on the nonoptimal electrode materials. The test bed structures and absorber synthesis processes are amenable to an array of deposition techniques for fabrication and measurements of three dimensionally structured semiconductors, contact materials, and photovoltaic devices subject to processing feasibility and materials compatibility.

  1. Peel-and-stick: fabricating thin film solar cell on universal substrates.

    PubMed

    Lee, Chi Hwan; Kim, Dong Rip; Cho, In Sun; William, Nemeth; Wang, Qi; Zheng, Xiaolin

    2012-01-01

    Fabrication of thin-film solar cells (TFSCs) on substrates other than Si and glass has been challenging because these nonconventional substrates are not suitable for the current TFSC fabrication processes due to poor surface flatness and low tolerance to high temperature and chemical processing. Here, we report a new peel-and-stick process that circumvents these fabrication challenges by peeling off the fully fabricated TFSCs from the original Si wafer and attaching TFSCs to virtually any substrates regardless of materials, flatness and rigidness. With the peel-and-stick process, we integrated hydrogenated amorphous silicon (a-Si:H) TFSCs on paper, plastics, cell phone and building windows while maintaining the original 7.5% efficiency. The new peel-and-stick process enables further reduction of the cost and weight for TFSCs and endows TFSCs with flexibility and attachability for broader application areas. We believe that the peel-and-stick process can be applied to thin film electronics as well.

  2. Thin-Film Solar Cells on Polymer Substrates for Space Power

    NASA Technical Reports Server (NTRS)

    Hepps, A. F.; McNatt, Jeremiah; Morel, D. L.; Ferckides, C. S.; Jin, M. H.; Orbey, N.; Cushman, M.; Birkmire, R. W.; Shafarman, W. N.; Newton, R.

    2004-01-01

    Photovoltaic arrays have played a key role in power generation in space. The current technology will continue to evolve but is limited in the important mass specific power metric (MSP or power/weight ratio) because it is based on bulk crystal technology. Solar cells based on thin-film materials offer the promise of much higher MSP and much lower cost. However, for many space applications, a 20% or greater AM0 efficiency (eta) may be required. The leading thin-film materials, amorphous Si, CuInSe, and CdTe have seen significant advances in efficiency over the last decade but will not achieve the required efficiency in the near future. Several new technologies are herein described to maximize both device eta and MSP. We will discuss these technologies in the context of space exploration and commercialization. One novel approach involves the use of very lightweight polyimide substrates. We describe efforts to enable this advance including materials processing and device fabrication and characterization. Another approach involves stacking two cells on top of each other. These tandem devices more effectively utilize solar radiation by passing through non-absorbed longer wavelength light to a narrow-bandgap bottom cell material. Modeling of current devices in tandem format indicates that AM0 efficiencies near 20% can be achieved with potential for 25% in the near future. Several important technical issues need to be resolved to realize the benefits of lightweight technologies for solar arrays, such as: monolithic interconnects, lightweight array structures, and new ultra-light support and deployment mechanisms. Recent advances will be stressed.

  3. Individual identification of free hole and electron dynamics in CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films by simultaneous monitoring of two optical transitions

    SciTech Connect

    Okano, Makoto; Hagiya, Hideki; Sakurai, Takeaki; Akimoto, Katsuhiro; Shibata, Hajime; Niki, Shigeru; Kanemitsu, Yoshihiko

    2015-05-04

    The photocarrier dynamics of CuIn{sub 1−x}Ga{sub x}Se{sub 2} (CIGS) thin films were studied using white-light transient absorption (TA) measurements, as an understanding of this behavior is essential for improving the performance of solar cells composed of CIGS thin films. A characteristic double-peak structure due to the splitting of the valence bands in the CIGS was observed in the TA spectra under near-band-gap resonant excitation. From a comparison of the TA decay dynamics monitored at these two peaks, it was found that the slow-decay components of the electron and hole relaxation are on the nanosecond timescale. This finding is clear evidence of the long lifetimes of free photocarriers in polycrystalline CIGS thin films.

  4. Interfacial quality improvement of Cu(In,Ga)Se2 thin film solar cells by Cu-depletion layer formation

    NASA Astrophysics Data System (ADS)

    Nishimura, Takahito; Toki, Soma; Sugiura, Hiroki; Nakada, Kazuyoshi; Yamada, Akira

    2016-09-01

    Se irradiation with time, t Se, was introduced after the second stage of a three-stage process to control the Cu2Se layer during Cu(In,Ga)Se2 (CIGS) deposition. Open circuit voltage and fill factor of CIGS solar cells could be improved by introducing Se irradiation. We concluded that the control of the Cu2Se layer led to the formation of a Cu-depletion CIGS layer (CDL), which improved conversion efficiency owing to suppression of interfacial recombination by a valence band offset formed between CIGS and the CDL. Finally, highest efficiency of 19.8% was achieved with t Se of 5 min. This very simple and new technique is promising for the improvement of photovoltaic performance.

  5. Synthesis of nanostructured CuInS2 thin films and their application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhao, Yu; Luo, Fazhi; Zhuang, Mixue; Liu, Zhen; Wei, Aixiang; Liu, Jun

    2016-03-01

    CuInS2 (CIS) nanostructure thin films were successfully synthesized on FTO conductive glass substrates by solvothermal method. It is found that the surface morphology and microstructure of CIS thin films can be tailored by simply adjusting the concentration of oxalic acid. CIS nanostructure films with texture of "nanosheet array" and "flower-like microsphere" were obtained and used as Pt-free counter electrode for dye-sensitized solar cells (DSSCs). The nanosheet array CIS was found to have a better electrocatalytic activity than the flower-like microsphere one. DSSCs based on nanosheet array CIS thin film counter electrode show conversion efficiency of 3.33 %, which is comparable to the Pt-catalyzed DSSCs. The easy synthesis, low cost, morphology tunable and excellent electrocatalytic property may make the CuInS2 nanostructure competitive as counter electrode in DSSCs.

  6. CdS/CdTe thin-film solar cell with a zinc stannate buffer layer

    NASA Astrophysics Data System (ADS)

    Wu, X.; Sheldon, P.; Mahathongdy, Y.; Ribelin, R.; Mason, A.; Moutinho, H. R.; Coutts, T. J.

    1999-03-01

    This paper describes an improved CdS/CdTe polycrystalline thin-film solar-cell device structure that integrates a zinc stannate (Zn2SnO4 or ZTO) buffer layer between the transparent conductive oxide (TCO) layer and the CdS window layer. Zinc stannate films have a high bandgap, high transmittance, low absorptance, and low surface roughness. In addition, these films are chemically stable and exhibit higher resistivities that are roughly matched to that of the CdS window layer in the device structure. Preliminary device results have demonstrated that by integrating a ZTO buffer layer in both SnO2-based and Cd2SnO4 (CTO)-based CdS/CdTe devices, performance and reproducibility can be significantly enhanced.

  7. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    PubMed Central

    Major, J. D.; Al Turkestani, M.; Bowen, L.; Brossard, M.; Li, C.; Lagoudakis, P.; Pennycook, S. J.; Phillips, L. J.; Treharne, R. E.; Durose, K.

    2016-01-01

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated that while improvements in fill factor and short circuit current may be achieved through use of the ineffective chlorides, or indeed simple air annealing, voltage improvement is linked directly to chlorine incorporation at the grain boundaries. This suggests that focus on improved or more controlled grain boundary treatments may provide a route to achieving higher cell voltages and thus efficiencies. PMID:27775037

  8. Perovskite solar cells based on nanocolumnar plasma-deposited ZnO thin films.

    PubMed

    Ramos, F Javier; López-Santos, Maria C; Guillén, Elena; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

    2014-04-14

    ZnO thin films having a nanocolumnar microstructure are grown by plasma-enhanced chemical vapor deposition at 423 K on pre-treated fluorine-doped tin oxide (FTO) substrates. The films consist of c-axis-oriented wurtzite ZnO nanocolumns with well-defined microstructure and crystallinity. By sensitizing CH3NH3PbI3 on these photoanodes a power conversion of 4.8% is obtained for solid-state solar cells. Poly(triarylamine) is found to be less effective when used as the hole-transport material, compared to 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), while the higher annealing temperature of the perovskite leads to a better infiltration in the nanocolumnar structure and an enhancement of the cell efficiency.

  9. Studying nanostructured nipple arrays of moth eye facets helps to design better thin film solar cells.

    PubMed

    Dewan, Rahul; Fischer, Stefan; Meyer-Rochow, V Benno; Özdemir, Yasemin; Hamraz, Saeed; Knipp, Dietmar

    2012-03-01

    Nipples on the surface of moth eye facets exhibit almost perfect broadband anti-reflection properties. We have studied the facet surface micro-protuberances, known as corneal nipples, of the chestnut leafminer moth Cameraria ohridella by atomic force microscopy, and simulated the optics of the nipple arrays by three-dimensional electromagnetic simulation. The influence of the dimensions and shapes of the nipples on the optics was studied. In particular, the shape of the nipples has a major influence on the anti-reflection properties. Furthermore, we transferred the structure of the almost perfect broadband anti-reflection coatings to amorphous silicon thin film solar cells. The coating that imitates the moth-eye array allows for an increase of the short circuit current and conversion efficiency of more than 40%.

  10. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    DOE PAGES

    Major, J. D.; Al Turkestani, M.; Bowen, L.; ...

    2016-10-24

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated that while improvements in fill factor and short circuit current may be achieved through use of the ineffective chlorides, or indeed simple air annealing, voltage improvement is linked directlymore » to chlorine incorporation at the grain boundaries. Lastly, this suggests that focus on improved or more controlled grain boundary treatments may provide a route to achieving higher cell voltages and thus efficiencies.« less

  11. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    SciTech Connect

    Major, J. D.; Al Turkestani, M.; Bowen, L.; Brossard, M.; Li, C.; Lagoudakis, P.; Pennycook, Stephen J.; Phillips, L. J.; Treharne, R. E.; Durose, K.

    2016-10-24

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated that while improvements in fill factor and short circuit current may be achieved through use of the ineffective chlorides, or indeed simple air annealing, voltage improvement is linked directly to chlorine incorporation at the grain boundaries. Lastly, this suggests that focus on improved or more controlled grain boundary treatments may provide a route to achieving higher cell voltages and thus efficiencies.

  12. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Major, J. D.; Al Turkestani, M.; Bowen, L.; Brossard, M.; Li, C.; Lagoudakis, P.; Pennycook, S. J.; Phillips, L. J.; Treharne, R. E.; Durose, K.

    2016-10-01

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated that while improvements in fill factor and short circuit current may be achieved through use of the ineffective chlorides, or indeed simple air annealing, voltage improvement is linked directly to chlorine incorporation at the grain boundaries. This suggests that focus on improved or more controlled grain boundary treatments may provide a route to achieving higher cell voltages and thus efficiencies.

  13. Antireflective downconversion ZnO:Er3+,Yb3+ thin film for Si solar cell applications

    NASA Astrophysics Data System (ADS)

    Elleuch, R.; Salhi, R.; Deschanvres, J.-L.; Maalej, R.

    2015-02-01

    Hexagonal wurtzite phased ZnO:Er3+/Yb3+ thin films with various Yb concentrations were deposited on Si(111) substrate by Aerosol Assisted Chemical Vapor Deposition process. Post-annealed films at 1000 °C in air atmosphere showed a crystallinity enhancement. Yb3+ (4F7/2 → 4F5/2) 1000 nm emission increased with the increase of Yb3+ concentration emanating from an Er-Yb energy transfer. The reflectance percentage of 12% was achieved in the [250-1000 nm] range, and the refractive index of 1.97 was obtained for 632 nm wavelength. These results suggest that the (3 mol. % Er, 9 mol. % Yb) codoped film is a highly efficient antireflective downconversion layer for enhancing Si solar cell efficiency.

  14. Tailoring randomly rough textures for light trapping in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Kowalczewski, Piotr; Bozzola, Angelo; Liscidini, Marco; Andreani, Lucio Claudio

    2014-05-01

    In this contribution, we use a rigorous electro-optical model to study randomly rough crystalline silicon solar cells with the absorber thickness ranging from 1 to 100 μm. We demonstrate a significant efficiency enhancement, particularly strong for thin cells. We estimate the "region of interest" for thin-film photovoltaics, namely the thickness range for which the energy conversion efficiency reaches maximum. This optimal thickness results from the opposite trends of current and voltage as a function of the absorber thickness. Finally, we focus on surface recombination. In our design, the cell efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore engineering the front surface to a large extent does not reduce the efficiency. The presented model of roughness adds a significant functionality to previous approaches, for it allows performing rigorous calculations at a much reduced computational cost.

  15. Commercial-scale process design for thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Russell, T. W. F.; Baron, B. N.; Rocheleau, R. E.

    Process and manufacturing costs for commercial-scale production of thin-film solar cells are examined from the viewpoint of the chemical process industry, with emphasis on CdS/Cu2S cells. The cells comprise opaque contact, collector/converter, absorber/generator, transparent contact, and encapsulation/antireflective coating layers. Each layer is deposited as a separate unit operation, through either continuous or batch processing methods. The scale-up of laboratory-verified cell manufacturing steps to commercial processing is detailed from the choice of a Zn-plated copper foil substrate to the bonding of a 1/16 in. tempered glass protective layer with polyvinyl butyral. The total product cost is calculated as a sum of raw materials, utilities, labor, and capital investment costs, using a cost/W for a 1 GW plant. Continuous processing results in a $0.50/W cell with raw materials accounting for 38% of the total product cost.

  16. Dip coated nanocrystalline CdZnS thin films for solar cell application

    NASA Astrophysics Data System (ADS)

    Dongre, J. K.; Chaturvedi, Mahim; Patil, Yuvraj; Sharma, Sandhya; Jain, U. K.

    2015-07-01

    Nanocrystalline cadmium sulfide (CdS) and zinc cadmium sulfide (ZnCdS) thin films have been grown via simple and low cost dip coating technique. The prepared films are characterized by X-ray diffraction (XRD), atomic force microscopic (AFM) and UV-VIS spectrophotometer techniques to reveal their structural, morphological and optical properties. XRD shows that both samples grown have zinc blende structure. The grain size is calculated as 6.2 and 8 nm using Scherrer's formula. The band gap value of CdS and CdZnS film is estimated to be 2.58 and 2.69 eV respectively by UV-vis spectroscopy. Photoelectrochemical (PEC) investigations are carried out using cell configuration as n-CdZnS/(1M NaOH + 1M Na2S + 1M S)/C. The photovoltaic output characteristic is used to calculate fill-factor (FF) and solar conversion efficiency (η).

  17. Criteria for the design of high efficiency thin film solar cells - Theory and practice

    NASA Astrophysics Data System (ADS)

    Rothwarf, Allen

    1987-08-01

    The design and processing of thin-film solar cells involves 20 - 30 material- and processing-related parameters, each of which can produce at least a 5-percent variation in the output of the cell. Hence, to achieve a high efficiency cell, virtually all of them must be controlled. Each of the four types of cell that have achieved efficiencies greater than 10 percent have specific problems which are not well understood. Progress in improving cell performance has been achieved by a combination of empiricism and modeling. The models for the heterojunction cells Cu2S/CdZnS and CuInSe2/CdZnS are discussed, as well as the empirical approaches that have been succesful in improving cell performance.

  18. Thin-Film Multilayer Filter Designs For Hybrid Solar Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    DeSandre, L.; Song, D. Y.; Macleod, H. A.; Jacobson, M. R.; Osborn, D. E.

    1985-12-01

    The efficiency of hybrid photothermal/photovoltaic energy conversion can be increased by separating the solar spectrum into portions matched to the photothermal and photovoltaic processes. Thin-film multilayer filters can implement this concept; five such filters consisting of all-dielectric or metal-dielectric layers have been designed. The transmission profile of each design is calculated by computer, considering dispersion, absorption, and angle of incidence effects. These profiles are compared and evaluated with respect to the desired spectral performance. The most successful candidate design is an optical minus filter consisting of Ti02, Zr02, and Si02. Results show very sharp selection of the targeted photovoltaic spectral region and low ripple in the transmission region outside the bandstop.

  19. Formation of thin films of organic-inorganic perovskites for high-efficiency solar cells.

    PubMed

    Stranks, Samuel D; Nayak, Pabitra K; Zhang, Wei; Stergiopoulos, Thomas; Snaith, Henry J

    2015-03-09

    Organic-inorganic perovskites are currently one of the hottest topics in photovoltaic (PV) research, with power conversion efficiencies (PCEs) of cells on a laboratory scale already competing with those of established thin-film PV technologies. Most enhancements have been achieved by improving the quality of the perovskite films, suggesting that the optimization of film formation and crystallization is of paramount importance for further advances. Here, we review the various techniques for film formation and the role of the solvents and precursors in the processes. We address the role chloride ions play in film formation of mixed-halide perovskites, which is an outstanding question in the field. We highlight the material properties that are essential for high-efficiency operation of solar cells, and identify how further improved morphologies might be achieved.

  20. One-pot Synthesis of Soluble Nanoscale CIGS Photoactive Functional Materials.

    PubMed

    Lin, Ying; Chen, Yu; Feng, Miao; Yan, Aixia; Zhuang, Xiaodong

    2007-12-04

    Promising alternatives for solar energy utilization are thin film technologies involving various new materials. This contribution describes an easy and inexpensive synthetic method that can be used to prepare soluble nanoscale triphenyl phosphine-coordinated CIGS (TPP-CIGS) photoactive functional materials. This complex is stable in the solid state under the irradiation of the ambient light, but its solution becomes a little bit unstable under the illumination of the low intensity laser.

  1. Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture.

    PubMed

    Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

    2014-08-22

    Introducing light trapping structures into thin-film solar cells has the potential to enhance their solar energy harvesting as well as the performance of the cells; however, current strategies have been focused mainly on harvesting photons without considering the light re-escaping from cells in two-dimensional scales. The lateral out-coupled solar energy loss from the marginal areas of cells has reduced the electrical yield indeed. We therefore herein propose a lateral light trapping structure (LLTS) as a means of improving the light-harvesting capacity and performance of cells, achieving a 13.07% initial efficiency and greatly improved current output of a-Si:H single-junction solar cell based on this architecture. Given the unique transparency characteristics of thin-film solar cells, this proposed architecture has great potential for integration into the windows of buildings, microelectronics and other applications requiring transparent components.

  2. Substrate temperature optimization for Cu(In, Ga)Se2 solar cells on flexible stainless steels

    NASA Astrophysics Data System (ADS)

    Liang, X.; Zhu, H.; Chen, J.; Zhou, D.; Zhang, C.; Guo, Y.; Niu, X.; Li, Z.; Mai, Y.

    2016-04-01

    Cu(In, Ga)Se2 (CIGS) thin films are deposited on flexible stainless steel (SS) substrates using the so called 3-stage co-evaporation process at different substrate temperatures ranging from 440 °C to 640 °C during the 2nd stage and the 3rd stage (TS2). The effects of TS2 on the properties of CIGS thin films are systematically investigated. It is found by secondary ion mass spectrometry measurement that CIGS thin films deposited at different TS2 show different Ga/(Ga + In) ratio (GGI) profiles along the growth direction. High TS2 facilitates the grain growth and leads to larger grain size. However, high TS2 worsens the spectral response of CIGS solar cells in the long wavelength range, which is partly attributed to the too much iron atom diffusion from the SS substrates into the CIGS thin films. All CIGS thin films show (112) preferred orientations with a shift to higher angle due to variation of compositions. A shoulder-like two-peak structure of (112) and (220/204) peaks appears for CIGS thin films deposited at lower TS2. Conversion efficiency of 11.3% is obtained for CIGS thin film solar cells deposited at the TS2 of 500 °C.

  3. Thin film polycrystalline silicon solar cells: first technical progress report, April 15, 1980-July 15, 1980

    SciTech Connect

    1980-07-01

    The objectives of this contract are to fabricate large area thin film silicon solar cells with AM1 efficiency of 10% or greater with good reproducibility and good yield and to assess the feasibility of implementing this process for manufacturing solar cells at a cost of $300/kWe. Efforts during the past quarter have been directed to the purification of metallurgical silicon, the preparation of substrates, and the fabrication and characterization of solar cells. The partial purification of metallurgical silicon by extraction with aqua regia has been investigated in detail, and the resulting silicon was analyzed by the atomic absorption technique. The unidirectional solidification of aqua regia-extracted metallurgical silicon on graphite was used for the preparation of substrates, and the impurity distribution in the substrate was also determined. Large area (> 30 cm/sup 2/) solar cells have been prepared from aqua regia-extracted metallurgical silicon substrates by the thermal reduction of trichlorosilane containing appropriate dopants. Chemically deposited tin-dioxide films were used as antireflection coatings. Solar cells with AM1 efficiencies of about 8.5% have been obtained. Their spectral response, minority carrier diffusion length, and I/sub sc/-V/sub oc/ relation have been measured.

  4. Surface Plasmon Polaritons in Metallic Nanostructures: Fundamentals and Their Application to Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Rockstuhl, Carsten; Fahr, Stephan; Lederer, Falk

    A surface plasmon polariton is a hybrid excitation where the electromagnetic field is resonantly coupled to a free carrier oscillation in noble metals. Once excited, a large enhancement of the local electromagnetic field and the amount of scattered light can be observed. Since both properties are beneficial for the purpose ofphoton management, in the past several years an increasing share of research was devoted to exploit such effects in solar cells. In this contribution, we review the fundamentals of surface plasmon polaritons and outline different approaches how to incorporate metallic nanostructures into solar cells. We detail to which extent they are useful to enhance the solar cell efficiency and describe different schemes for their experimental implementation. Emphasis is put on thin-film solar cells, since in this class of solar cells metallic nanostructures may have the largest impact. This chapter is written with the intention to make researchers from either the field of plasmonics or the field of photovoltaics familiar with their respective counterpart to foster research in this applied domain.

  5. Epitaxially grown polycrystalline silicon thin-film solar cells on solid-phase crystallised seed layers

    NASA Astrophysics Data System (ADS)

    Li, Wei; Varlamov, Sergey; Xue, Chaowei

    2014-09-01

    This paper presents the fabrication of poly-Si thin film solar cells on glass substrates using seed layer approach. The solid-phase crystallised P-doped seed layer is not only used as the crystalline template for the epitaxial growth but also as the emitter for the solar cell structure. This paper investigates two important factors, surface cleaning and intragrain defects elimination for the seed layer, which can greatly influence the epitaxial grown solar cell performance. Shorter incubation and crystallisation time is observed using a simplified RCA cleaning than the other two wet chemical cleaning methods, indicating a cleaner seed layer surface is achieved. Cross sectional transmission microscope images confirm a crystallographic transferal of information from the simplified RCA cleaned seed layer into the epi-layer. RTA for the SPC seed layer can effectively eliminate the intragrain defects in the seed layer and improve structural quality of both of the seed layer and the epi-layer. Consequently, epitaxial grown poly-Si solar cell on the RTA treated seed layer shows better solar cell efficiency, Voc and Jsc than the one on the seed layer without RTA treatment.

  6. Wurtzite CZTS nanocrystals and phase evolution to kesterite thin film for solar energy harvesting.

    PubMed

    Ghorpade, Uma V; Suryawanshi, Mahesh P; Shin, Seung Wook; Hong, Chang Woo; Kim, Inyoung; Moon, Jong H; Yun, Jae Ho; Kim, Jin Hyeok; Kolekar, Sanjay S

    2015-08-14

    A quaternary indium- and gallium-free kesterite (KS)-based compound, copper zinc tin sulfide (Cu2ZnSnS4, CZTS), has received significant attention for its potential applications in low cost and sustainable solar cells. It is well known that the reaction time, reactivity of the precursors, and types of capping ligands used during the synthesis of colloidal nanocrystals (NCs) strongly influence the crystallographic phase of the NCs. In this research, a non-toxic and green synthetic strategy for both the synthesis of CZTS NCs and the fabrication of a highly efficient CZTS absorber layers using an ink formulation without a toxic solvent, which meets the comprehensive framework for green chemistry that covers major aspects of the environmental strain, is demonstrated. In particular, pure metastable wurtzite (WZ) CZTS NCs are synthesized using the environmentally harmless, polyol mediated hot-injection (HI) technique at a low reaction temperature. The influence of the reaction time on the properties of the CZTS NCs is investigated in detail. Based on detailed reaction time dependent phase evolution, a possible growth and formation mechanism is proposed. Furthermore, a scalable, low cost, binder free ink formulation process without ligand exchange is developed using ethanol as the dispersal solvent. The as-prepared WZ-derived CZTS NC thin films are observed to undergo a phase transformation to KS during annealing in a sulfur vapor atmosphere via rapid thermal annealing above 500 °C, and surprisingly, this process results in fully sintered, compact and uniform CZTS thin films with large sized grains. The best solar cell device fabricated using a CZTS absorber that was sulfurized at an optimized temperature exhibits a power conversion efficiency of 2.44%, which is the highest efficiency obtained using the polyol-based HI route.

  7. Preparation of multiband structure with Cu2Se/Ga3Se2/In3Se2 thin films by thermal evaporation technique for maximal solar spectrum utilization

    NASA Astrophysics Data System (ADS)

    Mohan, A.; Rajesh, S.; Gopalakrishnan, M.

    2016-10-01

    The paper investigates and discusses the formation of multiband structure through the Cu2Se-Ga3Se-In3Se2 thin films for maximal solar spectrum utilization. Stacking different semiconductor materials with various band gaps were done by successive evaporation method. Based on the band gap values the layers are arranged (low to high bandgap from the substrate). The XRD results exhibits the formation of CIGS composites through this successive evaporation of Cu2Se/Ga3Se/In3Se2 and treating then with temperature. Scanning Electron Microscope images shows improved crystallinity with the reduction in the larger grain boundary scattering after annealing. Optical spectra shows the stronger absorption in an UV-Visible region and higher transmission in the infrared and near infrared region. The optical band gap values calculated for as prepared films is 2.20 eV and the band gap was split into 1.62, 1.92 eV and 2.27eV for annealed samples. This multiband structures are much needed to utilize the full solar spectrum.

  8. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    NASA Astrophysics Data System (ADS)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2016-05-01

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatch between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or

  9. A pilot investigation on laser annealing for thin-film solar cells: Crystallinity and optical properties of laser-annealed CdTe thin films by using an 808-nm diode laser

    NASA Astrophysics Data System (ADS)

    Kim, Nam-Hoon; Park, Chan Il; Park, Jinseong

    2013-02-01

    Compared to conventional furnace and rapid thermal annealing, laser annealing for heterojunctioned thin-film solar cells has several advantages including excellent annealing selectivity to the under-layers with a localized high temperature for a short process time. A continuous wave 808-nm diode laser was used for the laser annealing process of CdTe thin films for various output powers. The grains in the laser-annealed CdTe thin films grew along the C (111), H (110), and C (311) planes. Laser annealing resulted in an increase in grain size and a decrease in surface roughness. The optical band gap energy of the CdTe thin films was affected directly by the grain size, showing 1.460 eV and 1.415 eV for the as-deposited and laser-annealed CdTe thin films, respectively. The absorbance of the CdTe thin films with better crystallinity showed an improved value of 99.5-99.9% in the visible spectral region after laser annealing at an output power of 0.91 W.

  10. CIGSS Thin Film Solar Cells: Final Subcontract Report, 10 October 2001-30 June 2005

    SciTech Connect

    Dhere, N. G.

    2006-02-01

    This report describes the I-III-VI2 compounds that are developing into a promising material to meet the energy requirement of the world. CuInSe2 (CIS) and its alloy with Ga and S have shown long-term stability and highest conversion efficiency of 19.5%. Among the various ways of preparing CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells, co-evaporation and sputtering techniques are the most promising. Sputtering is an established process for very high-throughput manufacturing. ARCO Solar, now Shell Solar, pioneered the work in CIS using the sputtering technique. The two-stage process developed by ARCO Solar involved sputtering of a copper and indium layer on molybdenum-coated glass as the first step. In the second step, the copper-indium layers were exposed to a selenium-bearing gas such as hydrogen selenide (H2Se) mixed with argon. The hydrogen selenide breaks down and leaves selenium, which reacts and mixes with the copper and indium in such a way to produce very high-quality CIS absorber layer. Sputtering technology has the added advantage of being easily scaled up and promotes roll-to-roll production on flexible substrates. Preliminary experiments were carried out. ZnO/ZnO:Al deposition by RF magnetron sputtering and CdS deposition by chemical-bath deposition are being carried out on a routine basis.

  11. Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation

    NASA Astrophysics Data System (ADS)

    Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K.; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J.

    2015-12-01

    Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0-200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400-2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5-17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m-2. This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies.

  12. Silicon nanospheres for directional scattering in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-07-01

    Reducing active layer thickness of solar cell stresses on efficient light trapping mechanisms to keep the cell efficiency intact. Directional light scattering and promising refractive index of silicon nanoparticles make them encouraging scattering centers for thin-film silicon solar cells. Finite-difference time-domain simulations are used to study the optical properties of silicon nanospheres embedded in the top and bottom buffer layer of solar cells. Diameter of a silicon nanoparticle plays a crucial role in the forward and backward scattering of incident light into the cell. Silicon nanospheres outperform commonly used metallic and dielectric nanospheres and trapped the incident light over a broad spectrum. Silicon nanospheres require special attention when placed in both the buffer layers of the solar cell simultaneously, and lateral displacement of the silicon nanospheres at the top buffer layer with respect to nanospheres at the bottom buffer layer is beneficial. Lateral displacement of nanospheres provides a total quantum efficiency of 51.49% in comparison to 21.9% of the pristine cell. These exceptional scattering competencies of silicon nanospheres make them a promising candidate for photovoltaic applications. Silicon scatterers may be used with well-established fabrication techniques.

  13. Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation

    PubMed Central

    Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K.; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J.

    2015-01-01

    Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0–200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400–2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5–17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m−2. This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies. PMID:26657535

  14. Dye sensitized solar cells based on nanowire sculptured thin film titanium dioxide photoanodes

    NASA Astrophysics Data System (ADS)

    Pursel, Sean M.

    Energy harvested from the sun using photovoltaics (PVs) is a renewable resource in high demand. Photovoltaics convert photons into electron-hole pairs which are then separated and used for electrical power. 75 TW of energy arrives from the sun every year onto US soil. Harvesting it all would provide enough energy to power the entire world for more than five years. It is this abundance of energy that makes PVs an attractive alternative to fossil fuels. PVs currently produce 0.15% of the energy consumed in the US. Production needs to grow as the worldwide demand for energy is projected to almost double by 2050. Fundamental and device based PV research have made steady efficiency gains in silicon based devices and thin film devices have started to become commercially viable. However, less expensive devices with suitable efficiency have not been fully developed. Dye sensitized solar cells (DSSCs) are one such device which has been optimized using standard components. However, device efficiency has not increased significantly since DSSCs were first conceived in 1991. Interestingly, none of the standard components are optimized, but act in a synergistic way in the most efficient devices. This research, along with other parallel research, attempts to optimize a single component of DSSCs with the goal of combining efforts to produce a device with increased efficiency. This research attempts to optimize the TiO2 photoanode used in DSSCs in terms of electron collection, dye coverage, light harvesting, and novel electrolyte infiltration by replacing the standard colloidal structure with nanowires deposited using physical vapor deposition at an oblique angle to form sculptured thin films. The results are quantified through standard photovoltaic testing, electrochemical impedance spectroscopy, UV-Vis-NIR spectroscopy, and general materials characterization techniques. The nanowire photoanodes are engineered during deposition using reactive evaporation, substrate heating

  15. Investigation of solar cell performance using multilayer thin film structure (SiO2/Si3N4) and grating

    NASA Astrophysics Data System (ADS)

    Dubey, R. S.; Jhansirani, K.; Singh, Shyam

    Thin film silicon solar cells are the better choice due to their low cost as compared to the crystalline solar cells. However, thin film silicon solar cells are suffering from a problem of weak absorption of incident light and hence, light trapping mechanism is essential for the harvesting of maximum solar radiation. In this paper, we present the performance of solar cell using an efficient back reflector composed of multilayer thin film (SiO2/Si3N4) and a diffraction grating. The use of a back reflector showed enhanced light absorption due to the folding of unabsorbed light coming to it after crossing the active region in a wide wavelength range. Further, the effect of active layer thickness and grating height were also discussed for the optimal performance of the solar cell. In the case of magnetic transverse mode, a relative enhancement in cell efficiency about 79 and 21% respectively have been observed with respect to a planar and SC4 solar cells.

  16. Development of High Band Gap Absorber and Buffer Materials for Thin Film Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Dwyer, Dan

    2011-12-01

    CuInGaSe2 (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, alpha-Si, CuInSe2). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models [1]. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes any combination of the cations Cu, Al, Ga, and In along with the anions S, Se, and Te). This thesis focuses on the second option, substituting aluminum for gallium in the chalcopyrite lattice to form a CuInAlSe2 (CIAS) film using a sputtering and selenization approach. Both sequential and co-sputtering of metal precursors is performed. Indium was found to be very mobile during both sputtering processes, with a tendency to diffuse to the film surface even when deposited as the base layer in a sequential sputtering process. Elemental diffusion was controlled to a degree using thicker Cu top layer in co-sputtering. The greater thermal conductivity of stainless steel foil (16 W/mK) vs. glass (0.9-1.3 W/mK) can also be used to limit indium diffusion, by keeping the substrate cooler during sputtering. In both sputtering methods aluminum is deposited oxygen-free by capping the film with a Cu capping layer in combination with controlling the indium diffusion. Selenization of metal precursor films is completed using two different techniques. The first is a thermal evaporation approach from a heated box source (method 1 -- reactive thermal evaporation (RTE-Se)). The second is batch selenization using a heated tube furnace (method 2 -- batch selenization). Some batch selenized precursors were capped with ˜ 1mum of selenium. In both selenization methods

  17. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    PubMed

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-07

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.

  18. Amorphous Indium Selenide Thin Films Prepared by RF Sputtering: Thickness-Induced Characteristics.

    PubMed

    Han, Myoung Yoo; Park, Yong Seob; Kim, Nam-Hoon

    2016-05-01

    The influence of indium composition, controlled by changing the film thickness, on the optical and electrical properties of amorphous indium selenide thin films was studied for the application of these materials as Cd-free buffer layers in CI(G)S solar cells. Indium selenide thin films were prepared using RF magnetron sputtering method. The indium composition of the amorphous indium selenide thin films was varied from 94.56 to 49.72 at% by increasing the film thickness from 30 to 70 nm. With a decrease in film thickness, the optical transmittance increased from 87.63% to 96.03% and Eg decreased from 3.048 to 2.875 eV. Carrier concentration and resistivity showed excellent values of ≥1015 cm(-3) and ≤ 10(4) Ω x cm, respectively. The conductivity type of the amorphous indium selenide thin films could be controlled by changing the film-thickness-induced amount of In. These results indicate the possibility of tuning the properties of amorphous indium selenide thin films by changing their composition for use as an alternate buffer layer material in CI(G)S solar cells.

  19. Influence of patterning the TCO layer on the series resistance of thin film HIT solar cells

    NASA Astrophysics Data System (ADS)

    Champory, Romain; Mandorlo, Fabien; Seassal, Christian; Fave, Alain

    2017-01-01

    Thin HIT solar cells combine efficient surface passivation and high open circuit voltage leading to high conversion efficiencies. They require a TCO layer in order to ease carriers transfer to the top surface fingers. This Transparent Conductive Oxide layer induces parasitic absorption in the low wavelength range of the solar spectrum that limits the maximum short circuit current. In case of thin film HIT solar cells, the front surface is patterned in order to increase the effective life time of photons in the active material, and the TCO layer is often deposited with a conformal way leading to additional material on the sidewalls of the patterns. In this article, we propose an alternative scheme with a local etching of both the TCO and the front a-Si:H layers in order to reduce the parasitic absorption. We study how the local resistivity of the TCO evolves as a function of the patterns, and demonstrate how the increase of the series resistance can be compensated in order to increase the conversion efficiency.

  20. Light trapping in thin-film solar cells measured by Raman spectroscopy

    SciTech Connect

    Ledinský, M.; Moulin, E.; Bugnon, G.; Meillaud, F.; Ballif, C.; Ganzerová, K.; Vetushka, A.; Fejfar, A.

    2014-09-15

    In this study, Raman spectroscopy is used as a tool to determine the light-trapping capability of textured ZnO front electrodes implemented in microcrystalline silicon (μc-Si:H) solar cells. Microcrystalline silicon films deposited on superstrates of various roughnesses are characterized by Raman micro-spectroscopy at excitation wavelengths of 442 nm, 514 nm, 633 nm, and 785 nm, respectively. The way to measure quantitatively and with a high level of reproducibility the Raman intensity is described in details. By varying the superstrate texture and with it the light trapping in the μc-Si:H absorber layer, we find significant differences in the absolute Raman intensity measured in the near infrared wavelength region (where light trapping is relevant). A good agreement between the absolute Raman intensity and the external quantum efficiency of the μc-Si:H solar cells is obtained, demonstrating the validity of the introduced method. Applications to thin-film solar cells, in general, and other optoelectronic devices are discussed.

  1. Tailored heterojunctions for efficient thin-film organic solar cells: a photoinduced absorption study

    NASA Astrophysics Data System (ADS)

    Schueppel, R.; Schmidt, K.; Uhrich, C.; Schulze, K.; Wynands, D.; Brédas, J. L.; Maennig, B.; Pfeiffer, M.; Leo, K.; Brier, E.; Reinold, E.; Bu, H.-B.; Baeuerle, P.

    2007-09-01

    Recently, we have demonstrated an open circuit voltage of 1.0V and a power conversion efficiency of 3.4% in thin film solar cells, utilizing a new acceptor-substituted oligothiophene with an optical gap of 1.77 eV as donor and C 60 as acceptor. Stimulated by this result, we systematically study the energy and electron transfer processes taking place at the oligothiophene:fullerene heterojunction along a homologous series of these oligothiophenes. The heterojunction is modified by tuning the HOMO level using different oligothiophene chain lengths, while the LUMO level is essentially fixed by the choice of the acceptor-type end-groups (dicyanovinyl) attached to the oligothiophene. We study electron transfer at the heterojunction to C 60 using photoinduced absorption. The observed transitions are unambiguously identified by TD-DFT calculations. With increasing the effective energy gap of the donor-acceptor pair, charge carrier dissociation following the photoinduced electron transfer is eventually replaced by recombination into the triplet state, which alters the photovoltaic operation conditions. Therefore, the optimum open-circuit voltage of a solar cell is a trade-off between an efficient charge separation at the interface and a maximized effective gap. We conclude that values between 1.0 and 1.1 V for the open-circuit voltage in our solar cell devices present an optimum, as higher voltages were only achieved with concomitant losses in charge separation efficiency.

  2. Series circuit of organic thin-film solar cells for conversion of water into hydrogen.

    PubMed

    Aoki, Atsushi; Naruse, Mitsuru; Abe, Takayuki

    2013-07-22

    A series circuit of bulk hetero-junction (BHJ) organic thin-film solar cells (OSCs) is investigated for electrolyzing water to gaseous hydrogen and oxygen. The BHJ OSCs applied consist of poly(3-hexylthiophene) as a donor and [6,6]-phenyl C61 butyric acid methyl ester as an acceptor. A series circuit of six such OSC units has an open circuit voltage (V(oc)) of 3.4 V, which is enough to electrolyze water. The short circuit current (J(sc)), fill factor (FF), and energy conversion efficiency (η) are independent of the number of unit cells. A maximum electric power of 8.86 mW cm(-2) is obtained at the voltage of 2.35 V. By combining a water electrolysis cell with the series circuit solar cells, the electrolyzing current and voltage obtained are 1.09 mA and 2.3 V under a simulated solar light irradiation (100 mW cm(-2), AM1.5G), and in one hour 0.65 mL hydrogen is generated.

  3. Advances in the Electrical Connection Technique of Thin Film Solar Cells on a Titanium Substrate

    NASA Astrophysics Data System (ADS)

    Zwanenburg, R.

    2008-09-01

    Dutch Space has developed a new solar blanket (the MATRIX) that consists of just Thin Film (TF) solar cells made on titanium substrates. The cells are electrically connected via a number of contact points (pressure contact only). It was found that degradation of these electrical contacts was mainly caused by a too low contact pressure. Measures have been taken to increase the contact pressure and number of contact points. An alternative contact method using conductive adhesive has been tested, but this solution failed as cell delamination from the substrate underneath the bonding spots was observed after thermal cycling tests. An improved contact system with four contact points along the cell width was implemented in an assembly of 24 new TF solar cells. Thermal cycling tests showed a stable performance of the electrical connection. Further improvements are foreseen using a new cell layout with 8 contact points. Unfortunately, cell delamination was observed after the thermal cycling testing. The adhesion between the cell coating and the molybdenum undercoat needs to be improved for the future production of TF cells.

  4. Semiperiodicity versus periodicity for ultra broadband optical absorption in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Jalali, Mandana; Nadgaran, Hamid; Erni, Daniel

    2016-07-01

    We propose the use of one-dimensional semiperiodic front and back gratings based on Thue-Morse, Fibonacci, and Rudin-Shapiro (RS) binary sequences as promising photon management techniques for enhancing ultra-broadband optical absorption in thin-film solar cells. The semiperiodicity allows an aggregate light in-coupling into the active layer within the range of the solar spectrum that is less weak compared to an inherently broadband random grating, but has a much larger bandwidth than the strong in-coupling via a periodic grating configuration. The proper design procedure proposed here deviates from a canonical double grating synthesis as it adheres to an ultra-broadband design where the spectrally integrated absorption in the active material is the proper subject to optimization, leaving the grating perturbations just a measure to perturb and mold the trapped light field in the active layer accordingly. It is shown that by using a well-defined RS double grating in a 400-nm thick crystalline silicon solar cell, a 110.2% enhancement of the spectrally integrated optical absorption can be achieved relative to the reference case without grating.

  5. Electro deposition of cuprous oxide for thin film solar cell applications

    NASA Astrophysics Data System (ADS)

    Shahrestani, Seyed Mohammad

    electro-deposition of Cu2O n-type were identified consistently for the first time. The electro-deposition electrolyte is based 0.01M acetate copper and 0.1 M sodium acetate: it has a pH between 6.3 and 4, a potential of from 0 to -0.25 V vs. Ag / AgCl and a temperature of 60oC. The optimum annealing temperature of the n-type Cu2O layers is between 120-150oC for the annealing time of 30 to 120 minutes. Resistivity of the n-type films varies between 5 x 103 and 5 x 104 at pH 4 to pH 6.4. We have shown for the first time that bubbling nitrogen gas in the electroplating cell improves significantly the spectral response of the electro-deposited n-type thin film. A two steps electro-deposition process was implemented to make the p-n homojunction cuprous oxide. Indium tin oxide (ITO) was used as a transparent conductive oxide substrate. A p-Cu2O was electrodeposited on ITO. After heat treatment a thin film layer of n-Cu 2O was electrodeposited on top of previous layer. The performance of a p-n homojunction photovoltaic solar cell of Cu2O was determined. The short-circuit current and the open circuit voltage were respectively determined to be as 0.35 volts and 235 muA/cm2. The fill factor (FF) and conversion efficiency of light into electricity were respectively measured to be 0.305 and 0.082%.

  6. Temperature-dependent electrical characteristics of c-Si and CIGS solar cells.

    PubMed

    Choi, Pyung Ho; Baek, Do Hyun; Park, Hyoung Sun; Kim, Sang Soo; Yi, Jun Sin; Kim, Sang Soo; Choi, Byoung Deog

    2014-12-01

    We characterized the electrical behavior of crystalline silicon (c-Si) and Cu(In(1-x)Ga(x))Se2 (CIGS) solar cells by current-voltage (I-V) and capacitance-voltage (C-V) methods. We investigated the temperature-dependent carrier transport mechanism by determining the parameters of ideality factor (n) and activation energy (E(a)) deduced from I-V measurements. CLGS solar cells, as a function of temperature, showed drastic changes in n and E(a) in the space charge region (SCR) that forms near the ZnS/CIGS interface. Furthermore, by using a C-V measured substrate doping profiling method, we confirmed that the CIGS absorption layer had a graded band-gap structure from the end point of the SCR to the CIGS/Mo back contacts, while c-Si solar cells had a uniformly doped carrier concentration.

  7. Self-aligned growth of thin film Cu(In,Ga)Se2 solar cells on various micropatterns

    NASA Astrophysics Data System (ADS)

    Duchatelet, A.; Nguyen, K.; Grand, P.-P.; Lincot, D.; Paire, M.

    2016-12-01

    We provide the demonstration of a self-aligned growth of thin film Cu(In,Ga)Se2 solar cells and microcells. We created Cu(In,Ga)Se2 solar cells by direct localized electrodeposition and annealing on two patterns: lines of 1105 μm and 105 μm width and 1 cm long. We obtained up to 7.6% efficiency on the 1105 μm wide lines and 5.3% efficiency on 105 μm wide lines. This work demonstrates the possibility to directly grow efficient solar cells on tunable patterns, with very efficient material usage. This is important in the perspective of thin film micro-concentrators and also semi-transparent photovoltaic windows for building integrated applications.

  8. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    SciTech Connect

    Pathirane, M. Iheanacho, B.; Lee, C.-H.; Wong, W. S.; Tamang, A.; Knipp, D.; Lujan, R.

    2015-10-05

    Hydrothermally synthesized disordered ZnO nanowires were conformally coated with a-Si:H thin-films to fabricate three dimensional hybrid nanowire/thin-film structures. The a-Si:H layer formed a radial junction p-i-n diode solar cell around the ZnO nanowire. The cylindrical hybrid solar cells enhanced light scattering throughout the UV-visible-NIR spectrum (300 nm–800 nm) resulting in a 22% increase in short-circuit current density compared to the reference planar p-i-n device. A fill factor of 69% and a total power conversion efficiency of 6.5% were achieved with the hybrid nanowire solar cells using a spin-on indium tin oxide nanoparticle suspension as the top contact.

  9. Symmetry-breaking nanostructures on crystalline silicon for enhanced light trapping in thin film solar cells.

    PubMed

    Han, Seok Jun; Ghosh, Swapnadip; Abudayyeh, Omar K; Hoard, Brittany R; Culler, Ethan C; Bonilla, Jose E; Han, Sang M; Han, Sang Eon

    2016-12-26

    We introduce a new approach to systematically break the symmetry in periodic nanostructures on a crystalline silicon surface. Our focus is inverted nanopyramid arrays with a prescribed symmetry. The arrangement and symmetry of nanopyramids are determined by etch mask design and its rotation with respect to the [110] orientation of the Si(001) substrate. This approach eliminates the need for using expensive off-cut silicon wafers. We also make use of low-cost, manufacturable, wet etching steps to fabricate the nanopyramids. Our experiment and computational modeling demonstrate that the symmetry breaking can increase the photovoltaic efficiency in thin-film silicon solar cells. For a 10-micron-thick active layer, the efficiency improves from 27.0 to 27.9% by enhanced light trapping over the broad sunlight spectrum. Our computation further reveals that this improvement would increase from 28.1 to 30.0% in the case of a 20-micron-thick active layer, when the unetched area between nanopyramids is minimized with over-etching. In addition to the immediate benefit to solar photovoltaics, our method of symmetry breaking provides a useful experimental platform to broadly study the effect of symmetry breaking on spectrally tuned light absorption and emission.

  10. Electrophoretic deposited TiO(2) pigment-based back reflectors for thin film solar cells.

    PubMed

    Bills, Braden; Morris, Nathan; Dubey, Mukul; Wang, Qi; Fan, Qi Hua

    2015-02-09

    Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This work reports titanium dioxide (TiO(2)) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si solar cell. Electrophoretic deposition is used to produce pigment-based back reflectors with high pigment density, controllable film thickness and site-specific deposition. Electrical conductivity of the pigment-based back reflectors is improved by creating electrical vias throughout the pigment-based back reflector by making holes using an electrical discharge / dielectric breakdown approach followed by a second electrophoretic deposition of conductive nanoparticles into the holes. While previous studies have demonstrated the use of pigment-based back reflectors, for example white paint, on glass superstrate configured thin film Si solar cells, this work presents a scheme for producing pigment-based reflectors on complex shape and flexible substrates. Mechanical durability and scalability are demonstrated on a continuous electrophoretic deposition roll-to-roll system which has flexible metal substrate capability of 4 inch wide and 300 feet long.

  11. Electrophoretic deposited TiO2 pigment-based back reflectors for thin film solar cells

    DOE PAGES

    Bills, Braden; Morris, Nathan; Dubey, Mukul; ...

    2015-01-16

    Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This paper reports titanium dioxide (TiO2) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si solar cell. Electrophoretic deposition is used to produce pigment-based back reflectors with high pigment density, controllable film thickness and site-specific deposition. Electrical conductivity of the pigment-based back reflectors is improved by creating electrical vias throughout the pigment-based back reflector by making holes using an electrical discharge / dielectric breakdownmore » approach followed by a second electrophoretic deposition of conductive nanoparticles into the holes. While previous studies have demonstrated the use of pigment-based back reflectors, for example white paint, on glass superstrate configured thin film Si solar cells, this work presents a scheme for producing pigment-based reflectors on complex shape and flexible substrates. Finally, mechanical durability and scalability are demonstrated on a continuous electrophoretic deposition roll-to-roll system which has flexible metal substrate capability of 4 inch wide and 300 feet long.« less

  12. The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.

    PubMed

    Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M

    2014-12-21

    The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization.

  13. Synthesis of FeS2 Nano Crystals for ink based thin film solar cells

    NASA Astrophysics Data System (ADS)

    Dhakal, Tara; Ganta, Lakshmi; Westgate, Charles

    2012-02-01

    With a band gap of 0.95 eV and high absorption coefficient (?10^5 cm-1), FeS2 is ideal for use as a p-type hetero-junction partner in a solar cell. Although pyrite is abundant in nature, getting the right phase for thin films is difficult due to the various phases of iron sulfides. We propose an ink based process for attaining the pyrite phase. Our experimental process involves use of low cost non-toxic chemicals for synthesis. The process involves reacting iron (II) chloride, 1, 2-hexadecanediol with 70% Oleylamine at 100 C for 1 hour followed by introduction of sulfur and reacting for 2 hours at 220 C. The reaction provides perfect nano crystals dispersed in a carbon based solution which is later subjected to centrifugation to separate the crystals. After multiple cleaning cycles, the crystals were dispersed in chloroform for uniform suspension. SEM image the film formed by drop casting followed by argon-annealing revealed that the nano-crystals were hexagonal with sizes ranging from 100-500nm with perfect symmetry. EDAX analysis showed the iron to sulfur atomic percentage ratio 1:1. The argon annealed film was then sulfurized using an organic sulfur source at 400 C, which gave a desired pyrite cubic phase. We will present the growth process and the efficiency data for this ink based FeS2 solar cell.

  14. InGaN-based thin film solar cells: Epitaxy, structural design, and photovoltaic properties

    SciTech Connect

    Sang, Liwen; Liao, Meiyong; Koide, Yasuo; Sumiya, Masatomo

    2015-03-14

    In{sub x}Ga{sub 1−x}N, with the tunable direct bandgaps from ultraviolet to near infrared region, offers a promising candidate for the high-efficiency next-generation thin-film photovoltaic applications. Although the adoption of thick InGaN film as the active region is desirable to obtain efficient light absorption and carrier collection compared to InGaN/GaN quantum wells structure, the understanding on the effect from structural design is still unclear due to the poor-quality InGaN films with thickness and difficulty of p-type doping. In this paper, we comprehensively investigate the effects from film epitaxy, doping, and device structural design on the performances of the InGaN-based solar cells. The high-quality InGaN thick film is obtained on AlN/sapphire template, and p-In{sub 0.08}Ga{sub 0.92}N is achieved with a high hole concentration of more than 10{sup 18 }cm{sup −3}. The dependence of the photovoltaic performances on different structures, such as active regions and p-type regions is analyzed with respect to the carrier transport mechanism in the dark and under illumination. The strategy of improving the p-i interface by using a super-thin AlN interlayer is provided, which successfully enhances the performance of the solar cells.

  15. Light trapping in thin-film solar cells with randomly rough and hybrid textures.

    PubMed

    Kowalczewski, Piotr; Liscidini, Marco; Andreani, Lucio Claudio

    2013-09-09

    We study light-trapping in thin-film silicon solar cells with rough interfaces. We consider solar cells made of different materials (c-Si and μc-Si) to investigate the role of size and nature (direct/indirect) of the energy band gap in light trapping. By means of rigorous calculations we demonstrate that the Lambertian Limit of absorption can be obtained in a structure with an optimized rough interface. We gain insight into the light trapping mechanisms by analysing the optical properties of rough interfaces in terms of Angular Intensity Distribution (AID) and haze. Finally, we show the benefits of merging ordered and disordered photonic structures for light trapping by studying a hybrid interface, which is a combination of a rough interface and a diffraction grating. This approach gives a significant absorption enhancement for a roughness with a modest size of spatial features, assuring good electrical properties of the interface. All the structures presented in this work are compatible with present-day technologies, giving recent progress in fabrication of thin monocrystalline silicon films and nanoimprint lithography.

  16. Impact of thermal annealing on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Dhaka, M. S.

    2016-06-01

    A study on impact of post-deposition thermal annealing on the physical properties of CdTe thin films is undertaken in this paper. The thin films of thickness 500 nm were grown on ITO and glass substrates employing thermal vacuum evaporation followed by post-deposition thermal annealing in air atmosphere within low temperature range 150-350 °C. These films were subjected to the XRD, UV-Vis NIR spectrophotometer, source meter, SEM coupled with EDS and AFM for structural, optical, electrical and surface topographical analysis respectively. The diffraction patterns reveal that the films are having zinc-blende cubic structure with preferred orientation along (111) and polycrystalline in nature. The crystallographic parameters are calculated and discussed in detail. The optical band gap is found in the range 1.48-1.64 eV and observed to decrease with thermal annealing. The current-voltage characteristics show that the CdTe films exhibit linear ohmic behavior. The SEM studies show that the as-grown films are homogeneous, uniform and free from defects. The AFM studies reveal that the surface roughness of films is observed to increase with annealing. The experimental results reveal that the thermal annealing has significant impact on the physical properties of CdTe thin films and may be used as absorber layer to the CdTe/CdS thin films solar cells.

  17. CdS quantum dots sensitized Cu doped ZnO nanostructured thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Poornima, K.; Gopala Krishnan, K.; Lalitha, B.; Raja, M.

    2015-07-01

    ZnO nanorods and Cu doped ZnO nanorods thin films have been prepared by simple hydrothermal method. CdS quantum dots are sensitized with Cu doped ZnO nanorod thin films using successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction study reveals that ZnO nanorods, and CdS quantum dot sensitized Cu doped ZnO nanorods exhibit hexagonal structure. The scanning electron microscope image shows the presence of ZnO nanorods. The average diameter and length of the aligned nanorod is 300 nm and 1.5 μm respectively. The absorption spectra shows that the absorption edge of CdS quantum dot sensitized ZnO nanorod thin film is shifted toward longer wavelength region when compared to the absorption edge of ZnO nanorods film. The conversion efficiency of the CdS quantum dot sensitized Cu doped ZnO nanorod thin film solar cell is 1.5%.

  18. Influence of thickness on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Dhaka, M. S.

    2016-02-01

    This paper presents the influence of thickness on physical properties of polycrystalline CdTe thin films. The thin films of thickness 450 nm, 650 nm and 850 nm were deposited employing thermal vacuum evaporation technique on glass and indium tin oxide (ITO) coated glass substrates. The physical properties of these as-grown thin films were investigated employing the X-ray diffraction (XRD), source meter, UV-Vis spectrophotometer, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The structural analysis reveals that the films have zinc-blende cubic structure and polycrystalline in nature with preferred orientation (111). The structural parameters like lattice constant, interplanar spacing, grain size, strain, dislocation density and number of crystallites per unit area are calculated. The average grain size and optical band gap are found in the range 15.16-21.22 nm and 1.44-1.63 eV respectively and observed to decrease with thickness. The current-voltage characteristics show that the electrical conductivity is observed to decrease with thickness. The surface morphology shows that films are free from crystal defects like pin holes and voids as well as homogeneous and uniform. The EDS patterns show the presence of cadmium and tellurium elements in the as grown films. The experimental results reveal that the film thickness plays significant role on the physical properties of as-grown CdTe thin films and higher thickness may be used as absorber layer to solar cells applications.

  19. New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells.

    PubMed

    Wang, DongLin; Su, Gang

    2014-11-24

    Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm-800 nm, the conversion efficiency of solar cells can be further enhanced.

  20. New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

    PubMed Central

    Wang, DongLin; Su, Gang

    2014-01-01

    Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm–800 nm, the conversion efficiency of solar cells can be further enhanced. PMID:25418477

  1. All-Nonvacuum-Processed CIGS Solar Cells Using Scalable Ag NWs/AZO-Based Transparent Electrodes.

    PubMed

    Wang, Mingqing; Choy, Kwang-Leong

    2016-07-06

    With record cell efficiency of 21.7%, CIGS solar cells have demonstrated to be a very promising photovoltaic (PV) technology. However, their market penetration has been limited due to the inherent high cost of the cells. In this work, to lower the cost of CIGS solar cells, all nonvacuum-processed CIGS solar cells were designed and developed. CIGS absorber was prepared by the annealing of electrodeposited metallic layers in a chalcogen atmosphere. Nonvacuum-deposited Ag nanowires (NWs)/AZO transparent electrodes (TEs) with good transmittance (92.0% at 550 nm) and high conductivity (sheet resistance of 20 Ω/□) were used to replace the vacuum-sputtered window layer. Additional thermal treatment after device preparation was conducted at 220 °C for a few of minutes to improve both the value and the uniformity of the efficiency of CIGS pixel cell on 5 × 5 cm substrate. The best performance of the all-nonvacuum-fabricated CIGS solar cells showed an efficiency of 14.05% with Jsc of 34.82 mA/cm(2), Voc of 0.58 V, and FF of 69.60%, respectively, which is comparable with the efficiency of 14.45% of a reference cell using a sputtered window layer.

  2. Electroluminescence of thin-film CdTe solar cells and modules

    NASA Astrophysics Data System (ADS)

    Raguse, John Michael

    Thin-film photovoltaics has the potential to be a major source of world electricity. Mitigation of non-uniformities in thin-film solar cells and modules may help improve photovoltaic conversion efficiencies. In this manuscript, a measurement technique is discussed in detail which has the capability of detecting such non-uniformities in a form useful for analysis. Thin-film solar cells emit radiation while operating at forward electrical bias, analogous to an LED, a phenomena known as electroluminescence (EL). This process relatively is inefficient for polycrystalline CdTe devices, on the order of 10-4%, as most of the energy is converted into heat, but still strong enough for many valuable measurements. A EL system was built at the Colorado State University Photovoltaics Laboratory to measure EL from CdTe cells and modules. EL intensity normalized to exposure time and injection current density has been found to correlate very well with the difference between ideal and measured open-circuit voltage from devices that include a GaAs cell, an AlGaAs LED, and several CdTe cells with variations in manufacturing. Furthermore, these data points were found to be in good agreement when overlaid with calibrated data from two additional sources. The magnitude of the inverse slope of the fit is in agreement with the thermal voltage and the intercept was found to have a value near unity, in agreement with theory. The expanded data set consists of devices made from one of seven different band gaps and spans eight decades of EQELED efficiencies. As expected, cells which exhibit major failure of light-dark J-V superposition did not follow trend of well-behaved cells. EL images of selected defects from CdTe cells and modules are discussed and images are shown to be highly sensitive to defects in devices, since the intensity depends exponentially on the cells' voltages. The EL technique has proven to be a useful high-throughput tool for screening of cells. In addition to EL images

  3. Processing and modeling issues for thin-film solar cell devices. Annual subcontract report, January 16, 1993--January 15, 1994

    SciTech Connect

    Birkmire, R.W.; Phillips, J.E.; Buchanan, W.A.; Hegedus, S.S.; McCandless, B.E.; Shafarman, W.N.; Yokimcus, T.A.

    1994-09-01

    The overall objective of the research presented in this report is to advance the development and acceptance of thin-film photovoltaic modules by increasing the understanding of film growth and processing and its relationship to materials properties and solar cell performance. The specific means toward meeting this larger goal include: (1) investigating scalable, cost-effective deposition processes; (2) preparing thin-film materials and device layers and completed cell structures; (3) performing detailed material and device analysis; and (4) participating in collaborative research efforts that address the needs of PV-manufacturers. These objectives are being pursued with CuInSe{sub 2}, CdTe and a-Si based solar cells.

  4. Sub-100 °C solution processed amorphous titania nanowire thin films for high-performance perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Wu, Wu-Qiang; Chen, Dehong; Huang, Fuzhi; Cheng, Yi-Bing; Caruso, Rachel A.

    2016-10-01

    The present work demonstrates a facile one-step process to fabricate thin films of amorphous titania nanowires on transparent conducting oxide substrates via hydrolysis of potassium titanium oxide oxalate in an aqueous solution at 90 °C. The resultant titania nanowire thin films (that have not undergone further annealing) are efficient electron transport layers in CH3NH3PbI3 perovskite solar cells, yielding full sun solar-to-electricity conversion efficiencies of up to 14.67% and a stabilized efficiency of 14.00% under AM 1.5G one sun illumination, comparable to high temperature sintered TiO2 counterparts. The high photovoltaic performance is attributed to the porous nanowire network that facilitates perovskite infiltration, its unique 1D geometry and excellent surface coverage for efficient electron transport, as well as suppressed charge recombination between FTO and perovskite.

  5. Zn (O,S) buffer layers by atomic layer deposition in Cu (In,Ga)Se2 based thin film solar cells: Band alignment and sulfur gradient

    NASA Astrophysics Data System (ADS)

    Platzer-Björkman, C.; Törndahl, T.; Abou-Ras, D.; Malmström, J.; Kessler, J.; Stolt, L.

    2006-08-01

    Thin film solar cells with the structure sodalimeglass /Mo/Cu(In,Ga)Se2/Zn(O,S)/ZnO/ZnO:Al are studied for varying thickness and sulfur content of the Zn (O,S) buffer layer. These Zn (O,S) layers were deposited by atomic layer deposition (ALD) at 120°C. Devices with no or small concentrations of sulfur in the buffer layer show low open-circuit voltages. This is explained by the cliff, or negative conduction-band offset (CBO), of -0.2eV measured by photoelectron spectroscopy (PES) and optical methods for the Cu (In,Ga)Se2 (CIGS)/ZnO interface. Devices with ZnS buffer layers exhibit very low photocurrent. This is expected from the large positive CBO (spike) of 1.2eV measured for the CIGS /ZnS interface. For devices with Zn (O,S) buffer layers, two different deposition recipes were found to yield devices with efficiencies equal to or above reference devices in which standard CdS buffer layers were used; ultrathin Zn (O,S) layers with S /Zn ratios of 0.8-0.9, and Zn (O,S) layers of around 30nm with average S /Zn ratios of 0.3. The sulfur concentration increases towards the CIGS interface as revealed by transmission electron microscopy and in vacuo PES measurements. The occurrence of this sulfur gradient in ALD-Zn (O,S) is explained by longer incubation time for ZnO growth compared to ZnS growth. For the Zn (O,S) film with high sulfur content, the CBO is large which causes blocking of the photocurrent unless the film is ultrathin. For the Zn (O,S) film with lower sulfur content, a CBO of 0.2eV is obtained which is close to ideal, according to simulations. Efficiencies of up to 16.4% are obtained for devices with this buffer layer.

  6. Thin-film monocrystalline-silicon solar cells based on a seed layer approach with 11% efficiency

    NASA Astrophysics Data System (ADS)

    Gordon, I.; Qiu, Y.; Van Gestel, D.; Poortmans, J.

    2010-09-01

    Solar modules made from thin-film crystalline-silicon layers of high quality on glass substrates could lower the price of photovoltaic electricity substantially. Almost half of the price of wafer-based silicon solar modules is currently due to the cost of the silicon wafers themselves. Using crystalline-silicon thin-film as the active material would substantially reduce the silicon consumption while still ensuring a high cell-efficiency potential and a stable cell performance. One way to create a crystalline-silicon thin film on glass is by using a seed layer approach in which a thin crystalline-silicon layer is first created on a non-silicon substrate, followed by epitaxial thickening of this layer. In this paper, we present new solar cell results obtained on 10-micron thick monocrystalline-silicon layers, made by epitaxial thickening of thin seed layers on transparent glass-ceramic substrates. We used thin (001)-oriented silicon single-crystal seed layers on glass-ceramic substrates provided by Corning Inc. that are made by a process based on anodic bonding and implant-induced separation. Epitaxial thickening of these seed layers was realized in an atmospheric-pressure chemical vapor deposition system. Simple solar cell structures in substrate configuration were made from the epitaxial mono-silicon layers. The Si surface was plasma-textured to reduce the front-side reflection. No other light trapping features were incorporated. Efficiencies of up to 11% were reached with Voc values above 600 mV indicating the good electronic quality of the material. We believe that by further optimizing the material quality and by integrating an efficient light trapping scheme, the efficiency potential of these single-crystal silicon thin films on glass-ceramics should be higher than 15%.

  7. An optimized efficient dual junction InGaN/CIGS solar cell: A numerical simulation

    NASA Astrophysics Data System (ADS)

    Farhadi, Bita; Naseri, Mosayeb

    2016-08-01

    The photovoltaic performance of an efficient double junction InGaN/CIGS solar cell including a CdS antireflector top cover layer is studied using Silvaco ATLAS software. In this study, to gain a desired structure, the different design parameters, including the CIGS various band gaps, the doping concentration and the thickness of CdS layer are optimized. The simulation indicates that under current matching condition, an optimum efficiency of 40.42% is achieved.

  8. Aqueous Solution-Phase Selenized CuIn(S,Se)2 Thin Film Solar Cells Annealed under Inert Atmosphere.

    PubMed

    Oh, Yunjung; Yang, Wooseok; Kim, Jimin; Woo, Kyoohee; Moon, Jooho

    2015-10-14

    A nonvacuum solution-based approach can potentially be used to realize low cost, roll-to-roll fabrication of chalcopyrite CuIn(S,Se)2 (CISSe) thin film solar cells. However, most solution-based fabrication methods involve highly toxic solvents and inevitably require sulfurization and/or postselenization with hazardous H2S/H2Se gases. Herein, we introduce novel aqueous-based Cu-In-S and Se inks that contain an amine additive for producing a high-quality absorber layer. CISSe films were fabricated by simple deposition of Cu-In-S ink and Se ink followed by annealing under an inert atmosphere. Compositional and phase analyses confirmed that our simple aqueous ink-based method facilitated in-site selenization of the CIS layer. In addition, we investigated the molecular structures of our aqueous inks to determine how crystalline chalcopyrite absorber layers developed without sulfurization and/or postselenization. CISSe thin film solar cells annealed at 550 °C exhibited an efficiency of 4.55% under AM 1.5 illumination. The low-cost, nonvacuum method to deposit chalcopyrite absorber layers described here allows for safe and simple processing of thin film solar cells.

  9. Optimal structure of light trapping in thin-film solar cells: dielectric nanoparticles or multilayer antireflection coatings?

    PubMed

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2014-08-10

    Recent research has found an alternative way to enhance light trapping of thin-film solar cells by using dielectric nanoparticles deposited on the cell surface. To improve the performance of light trapping, a systematic study on the influence of dielectric nanoparticles on enhancement efficiency is performed in this paper. We prove that the optimal dielectric nanoparticles are substantially equivalent to the multilayer antireflection coatings (ARCs) with a "low-high-low" dielectric constant profile. Moreover, it is demonstrated that the use of a simple two-layer SiO2/SiC ARC can reach 34.15% enhancement, which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC, and TiO2 nanoparticles. That means the optimal multilayer ARCs structure is obviously superior to the optimal dielectric nanoparticles structure, and the deposition of a simple two-layer SiO2/SiC structure on top of a thin-film silicon solar cell can significantly enhance photoelectron generation and hence, result in superior performance of thin-film solar cells.

  10. Cu-doped CdS and its application in CdTe thin film solar cell

    NASA Astrophysics Data System (ADS)

    Deng, Yi; Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao; Wang, Deliang

    2016-01-01

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the VCd- and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl2 annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  11. Characterization of thin film tandem solar cells by radiofrequency pulsed glow discharge - Time of flight mass spectrometry.

    PubMed

    Fernandez, Beatriz; Lobo, Lara; Reininghaus, Nies; Pereiro, Rosario; Sanz-Medel, Alfredo

    2017-04-01

    Beside low production costs and the use of nontoxic and abundant raw materials, silicon based thin-film solar cells have the advantage to be built up as multi junction devices like tandem or triple junction solar cells. Silicon thin film modules made of tandem cells with hydrogenated amorphous silicon (a-Si:H) top cell and microcrystalline (μc) Si:H bottom cell are available on the market. In this work, the analytical potential of state-of-the art radiofrequency (rf) pulsed glow discharge (PGD) time of flight mass spectrometry (TOFMS) commercial instrumentation is investigated for depth profiling analysis of tandem-junctions solar cells on 2mm thick glass substrate with 1µm thick ZnO:Al. Depth profile characterization of two thin film tandem photovoltaic devices was compared using millisecond and sub-millisecond rf-PGD regimes, as well as the so-called "low mass mode" available in the commercial instrument used. Two procedures for sample preparation, namely using flat or rough cell substrates, were compared and the distribution of dopant elements (phosphorous, boron and germanium) was investigated in both cases. Experimental results obtained by rf-PGD-TOFMS as well as electrical measurements of the samples showed that a worse depth resolution of dopant elements in the silicon layers (e.g. distribution of boron in a thicker region that suggests a diffusion of this dopant in the coating of the sample) found using a rough sample substrate was related to a higher power conversion efficiency.

  12. Cu-doped CdS and its application in CdTe thin film solar cell

    SciTech Connect

    Deng, Yi; Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao; Wang, Deliang

    2016-01-15

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the V{sub Cd{sup −}} and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl{sub 2} annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  13. Absorption enhancement in thin film a-Si solar cells with double-sided SiO2 particle layers

    NASA Astrophysics Data System (ADS)

    Chen, Le; Wang, Qing-Kang; Shen, Xiang-Qian; Chen, Wen; Huang, Kun; Liu, Dai-Ming

    2015-10-01

    Light absorption enhancement is very important for improving the power conversion efficiency of a thin film a-Si solar cell. In this paper, a thin-film a-Si solar cell model with double-sided SiO2 particle layers is designed, and then the underlying mechanism of absorption enhancement is investigated by finite difference time domain (FDTD) simulation; finally the feasible experimental scheme for preparing the SiO2 particle layer is discussed. It is found that the top and bottom SiO2 particle layers play an important role in anti-reflection and light trapping, respectively. The light absorption of the cell with double-sided SiO2 layers greatly increases in a wavelength range of 300 nm-800 nm, and the ultimate efficiency increases more than 22% compared with that of the flat device. The cell model with double-sided SiO2 particle layers reported here can be used in varieties of thin film solar cells to further improve their performances. Project supported by the National High-Tech Research and Development Program of China (Grant No. 2011AA050518), the University Research Program of Guangxi Education Department, China (Grant No. LX2014288), and the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2013GXNSBA019014).

  14. Methods for forming thin-film heterojunction solar cells from I-III-VI{sub 2}

    DOEpatents

    Mickelsen, R.A.; Chen, W.S.

    1985-08-13

    An improved thin-film, large area solar cell, and methods for forming the same are disclosed, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI{sub 2} chalcopyrite ternary materials which is vacuum deposited in a thin ``composition-graded`` layer ranging from on the order of about 2.5 microns to about 5.0 microns ({approx_equal}2.5 {mu}m to {approx_equal}5.0 {mu}m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii) a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion occurs (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer. 16 figs.

  15. Methods for forming thin-film heterojunction solar cells from I-III-VI.sub. 2

    DOEpatents

    Mickelsen, Reid A [Bellevue, WA; Chen, Wen S [Seattle, WA

    1985-08-13

    An improved thin-film, large area solar cell, and methods for forming the same, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI.sub.2 chalcopyrite ternary materials which is vacuum deposited in a thin "composition-graded" layer ranging from on the order ot about 2.5 microns to about 5.0 microns (.congruent.2.5 .mu.m to .congruent.5.0 .mu.m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, causes the The Government has rights in this invention pursuant to Contract No. EG-77-C-01-4042, Subcontract No. XJ-9-8021-1 awarded by the U.S. Department of Energy.

  16. Methods for forming thin-film heterojunction solar cells from I-III-VI[sub 2

    DOEpatents

    Mickelsen, R.A.; Chen, W.S.

    1982-06-15

    An improved thin-film, large area solar cell, and methods for forming the same are disclosed, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (1) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI[sub 2] chalcopyrite ternary materials which is vacuum deposited in a thin composition-graded'' layer ranging from on the order of about 2.5 microns to about 5.0 microns ([approx equal]2.5[mu]m to [approx equal]5.0[mu]m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (2), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, is allowed.

  17. Methods for forming thin-film heterojunction solar cells from I-III-VI.sub. 2

    DOEpatents

    Mickelsen, Reid A.; Chen, Wen S.

    1982-01-01

    An improved thin-film, large area solar cell, and methods for forming the same, having a relatively high light-to-electrical energy conversion efficiency and characterized in that the cell comprises a p-n type heterojunction formed of: (i) a first semiconductor layer comprising a photovoltaic active material selected from the class of I-III-VI.sub.2 chalcopyrite ternary materials which is vacuum deposited in a thin "composition-graded" layer ranging from on the order of about 2.5 microns to about 5.0 microns (.congruent.2.5.mu.m to .congruent.5.0.mu.m) and wherein the lower region of the photovoltaic active material preferably comprises a low resistivity region of p-type semiconductor material having a superimposed region of relatively high resistivity, transient n-type semiconductor material defining a transient p-n homojunction; and (ii), a second semiconductor layer comprising a low resistivity n-type semiconductor material; wherein interdiffusion (a) between the elemental constituents of the two discrete juxtaposed regions of the first semiconductor layer defining a transient p-n homojunction layer, and (b) between the transient n-type material in the first semiconductor layer and the second n-type semiconductor layer, causes the transient n-type material in The Government has rights in this invention pursuant to Contract No. EG-77-C-01-4042, Subcontract No. XJ-9-8021-1 awarded by the U.S. Department of Energy.

  18. Broadband light trapping in thin film solar cells with self-organized plasmonic nano-colloids.

    PubMed

    Mendes, Manuel J; Morawiec, Seweryn; Mateus, Tiago; Lyubchyk, Andriy; Águas, Hugo; Ferreira, Isabel; Fortunato, Elvira; Martins, Rodrigo; Priolo, Francesco; Crupi, Isodiana

    2015-03-27

    The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells' front surface formed from the deposition of material over the spherically shaped colloids.

  19. Relationship Between Absorber Layer Properties and Device Operation Modes For High Efficiency Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Ravichandran, Ram; Kokenyesi, Robert; Wager, John; Keszler, Douglas; CenterInverse Design Team

    2014-03-01

    A thin film solar cell (TFSC) can be differentiated into two distinct operation modes based on the transport mechanism. Current TFSCs predominantly exploit diffusion to extract photogenerated minority carriers. For efficient extraction, the absorber layer requires high carrier mobilities and long minority carrier lifetimes. Materials exhibiting a strong optical absorption onset near the fundamental band gap allows reduction of the absorber layer thickness to significantly less than 1 μm. In such a TFSC, a strong intrinsic electric field drives minority carrier extraction, resulting in drift-based transport. The basic device configuration utilized in this simulation study is a heterojunction TFSC with a p-type absorber layer. The diffusion/drift device operation modes are simulated by varying the thickness and carrier concentration of the absorber layer, and device performance between the two modes is compared. In addition, the relationship between device operation mode and transport properties, including carrier mobility and minority carrier lifetime are explored. Finally, candidate absorber materials that enable the advantages of a drift-based TFSC developed within the Center for Inverse Design are presented. School of Electrical Engineering and Computer Science.

  20. Dip coated nanocrystalline CdZnS thin films for solar cell application

    SciTech Connect

    Dongre, J. K. Chaturvedi, Mahim; Patil, Yuvraj; Sharma, Sandhya; Jain, U. K.

    2015-07-31

    Nanocrystalline cadmium sulfide (CdS) and zinc cadmium sulfide (ZnCdS) thin films have been grown via simple and low cost dip coating technique. The prepared films are characterized by X-ray diffraction (XRD), atomic force microscopic (AFM) and UV-VIS spectrophotometer techniques to reveal their structural, morphological and optical properties. XRD shows that both samples grown have zinc blende structure. The grain size is calculated as 6.2 and 8 nm using Scherrer’s formula. The band gap value of CdS and CdZnS film is estimated to be 2.58 and 2.69 eV respectively by UV-vis spectroscopy. Photoelectrochemical (PEC) investigations are carried out using cell configuration as n-CdZnS/(1M NaOH + 1M Na2S + 1M S)/C. The photovoltaic output characteristic is used to calculate fill-factor (FF) and solar conversion efficiency (η)

  1. Thin Film Silicon Nanowire/PEDOT:PSS Hybrid Solar Cells with Surface Treatment.

    PubMed

    Wang, Hao; Wang, Jianxiong; Hong, Lei; Tan, Yew Heng; Tan, Chuan Seng; Rusli

    2016-12-01

    SiNW/PEDOT:PSS hybrid solar cells are fabricated on 10.6-μm-thick crystalline Si thin films. Cells with Si nanowires (SiNWs) of different lengths fabricated using the metal-catalyzed electroless etching (MCEE) technique have been investigated. A surface treatment process using oxygen plasma has been applied to improve the surface quality of the SiNWs, and the optimized cell with 0.7-μm-long SiNWs achieved a power conversion efficiency (PCE) of 7.83 %. The surface treatment process is found to remove surface defects and passivate the SiNWs and substantially improve the average open circuit voltage from 0.461 to 0.562 V for the optimized cell. The light harvesting capability of the SiNWs has also been investigated theoretically using optical simulation. It is found that the inherent randomness of the MCEE SiNWs, in terms of their diameter and spacing, accounts for the excellent light harvesting capability. In comparison, periodic SiNWs of comparable dimensions have been shown to exhibit much poorer trapping and absorption of light.

  2. Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin-Film Solar Cells: Preprint

    SciTech Connect

    Pern, F. J.; Noufi, R.; Li, X.; DeHart, C.; To, B.

    2008-05-01

    The stability of intrinsic and Al-doped single- and bi-layer ZnO for thin-film CuInGaSe2 solar cells, along with Al-doped Zn1-xMgxO alloy and Sn-doped In2O3 (ITO) and F-doped SnO2, was evaluated by direct exposure to damp heat (DH) at 85oC and 85% relative humidity. The results show that the DH-induced degradation rates followed the order of Al-doped ZnO and Zn1-xMgxO >> ITO > F:SnO2. The degradation rates of Al:ZnO were slower for films of higher thickness, higher substrate temperature in sputter-deposition, and with dry-out intervals. As inferred from the optical micro-imaging showing the initiation and propagation of degrading patterns and regions, the degradation behavior appears similar for all TCOs, despite the obvious difference in the degradation rate. A degradation mechanism is proposed to explain the temporal process involving thermal hydrolysis.

  3. Thin Film Silicon Nanowire/PEDOT:PSS Hybrid Solar Cells with Surface Treatment

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Wang, Jianxiong; Hong, Lei; Tan, Yew Heng; Tan, Chuan Seng; Rusli

    2016-06-01

    SiNW/PEDOT:PSS hybrid solar cells are fabricated on 10.6-μm-thick crystalline Si thin films. Cells with Si nanowires (SiNWs) of different lengths fabricated using the metal-catalyzed electroless etching (MCEE) technique have been investigated. A surface treatment process using oxygen plasma has been applied to improve the surface quality of the SiNWs, and the optimized cell with 0.7-μm-long SiNWs achieved a power conversion efficiency (PCE) of 7.83 %. The surface treatment process is found to remove surface defects and passivate the SiNWs and substantially improve the average open circuit voltage from 0.461 to 0.562 V for the optimized cell. The light harvesting capability of the SiNWs has also been investigated theoretically using optical simulation. It is found that the inherent randomness of the MCEE SiNWs, in terms of their diameter and spacing, accounts for the excellent light harvesting capability. In comparison, periodic SiNWs of comparable dimensions have been shown to exhibit much poorer trapping and absorption of light.

  4. Development towards cell-to-cell monolithic integration of a thin-film solar cell and lithium-ion accumulator

    NASA Astrophysics Data System (ADS)

    Agbo, Solomon N.; Merdzhanova, Tsvetelina; Yu, Shicheng; Tempel, Hermann; Kungl, Hans; Eichel, Rüdiger-A.; Rau, Uwe; Astakhov, Oleksandr

    2016-09-01

    This work focuses on the potentials of monolithic integrated thin-film silicon solar cell and lithium ion cell in a simple cell-to-cell integration without any control electronics as a compact power solution for portable electronic devices. To demonstrate this we used triple-junction thin-film silicon solar cell connected directly to a lithium ion battery cell to charge the battery and in turn discharge the battery through the solar cell. Our results show that with appropriate voltage matching the solar cell provides efficient charging for lab-scale lithium ion storage cell. Despite the absence of any control electronics the discharge rate of the Li-ion cell through the non-illuminated solar cell can be much lower than the charging rate when the current voltage (IV) characteristics of the solar cell is matched properly to the charge-discharge characteristics of the battery. This indicates good sustainability of the ultimately simple integrated device. At the maximum power point, solar energy-to-battery charging efficiency of 8.5% which is nearly the conversion efficiency of the solar cell was obtained indicating potential for loss-free operation of the photovoltaic (PV)-battery integration. For the rest of the charging points, an average of 8.0% charging efficiency was obtained.

  5. Co-electroplated Kesterite Bifacial Thin-Film Solar Cells: A Study of Sulfurization Temperature.

    PubMed

    Ge, Jie; Chu, Junhao; Yan, Yanfa; Jiang, Jinchun; Yang, Pingxiong

    2015-05-20

    Earth-abundant material, kesterite Cu2ZnSnS4 (CZTS), demonstrates the tremendous potential to serve as the absorber layer for the bifacial thin-film solar cell. The exploration of appropriate sulfurization conditions including annealing temperature is significant to gain insight into the growth mechanism based on the substrates using transparent conductive oxides (TCO) and improve device performance. The kesterite solar absorbers were fabricated on ITO substrates by sulfurizing co-electroplated Cu-Zn-Sn-S precursors in argon diluted H2S atmosphere at different temperatures (475-550 °C) for 30 min. Experimental proof, including cross-section scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, UV-vis-NIR transmission spectrum, and Raman and far-infrared spectroscopy, is presented for the crystallization of CZTS on an ITO substrate and the interfacial reaction between the ITO back contact and CZTS absorber. The complete conversion of precursor into CZTS requires at least 500 °C sulfurization temperature. The aggressive interfacial reaction leading to the out-diffusion of In into CZTS to a considerable extent, formation of tin sulfides, and electrically conductive degradation of ITO back contact occurs at the sulfurization temperatures higher than 500 °C. The bifacial devices obtained by 520 °C sulfurization exhibit the best conversion efficiencies and open circuit voltages. However, the presence of non-ohmic back contact (secondary diode), the short minority lifetime, and the high interfacial recombination rates negatively limit the open circuit voltage, fill factor, and efficiency, evidenced by illumination/temperature-dependent J-V, frequency-dependent capacitance-voltage (C-V-f), time-resolved PL (TRPL), and bias-dependent external quantum efficiency (EQE) measurements.

  6. Chemically deposited thin films of sulfides and selenides of antimony and bismuth as solar energy materials

    NASA Astrophysics Data System (ADS)

    Nair, M. T.; Nair, Padmanabhan K.; Garcia, V. M.; Pena, Y.; Arenas, O. L.; Garcia, J. C.; Gomez-Daza, O.

    1997-10-01

    Chemical bath deposition techniques for bismuth sulfide, bismuth selenide, antimony sulfide, and antimony selenide thin films of about 0.20 - 0.25 micrometer thickness are reported. All these materials may be considered as solar absorber films: strong optical absorption edges, with absorption coefficient, (alpha) , greater than 104 cm-1, are located at 1.31 eV for Bi2Se3, 1.33 eV for Bi2S3, 1.8 eV for Sb2S3, and 1.35 eV for Sb2Se3. As deposited, all the films are nearly amorphous. However, well defined crystalline peaks matching bismuthinite (JCPDS 17- 0320), paraguanajuatite (JCPDS 33-0214), and stibnite (JCPDS 6-0474) and antimony selenide (JCPDS 15-0861) for Bi2S3, Bi2Se3, Sb2S3 and Sb2Se3 respectively, are observed when the films are annealed in nitrogen at 300 degrees Celsius. This is accompanied by a substantial modification of the electrical conductivity in the films: from 10-7 (Omega) -1 cm-1 (in as prepared films) to 10 (Omega) -1 cm-1 in the case of bismuth sulfide and selenide films, and enhancement of photosensitivity in the case of antimony sulfide films. The chemical deposition of a CuS/CuxSe film on these Vx- VIy films and subsequent annealing at 300 degrees Celsius for 1 h at 1 torr of nitrogen leads to the formation of p-type films (conductivity of 1 - 100 (Omega) -1 cm-1) of multinary composition. Among these, the formation of Cu3BiS3 (JCPDS 9-0488) and Cu3SbS4 (JCPDS 35- 0581), CuSbS2 (JCPDS 35-0413) have been clearly detected. Solar energy applications of these films are suggested.

  7. Processing and modeling issues for thin-film solar cell devices: Annual subcontract report, January 16, 1995 -- January 15, 1996

    SciTech Connect

    Birkmire, R W; Phillips, J E; Buchanan, W A; Eser, E; Hegedus, S S; McCandless, B E; Meyers, P V; Shafarman, W N

    1996-08-01

    The overall mission of the Institute of Energy Conversion is the development of thin film photovoltaic cells, modules, and related manufacturing technology and the education of students and professionals in photovoltaic technology. The objectives of this four-year NREL subcontract are to advance the state of the art and the acceptance of thin film PV modules in the areas of improved technology for thin film deposition, device fabrication, and material and device characterization and modeling, relating to solar cells based on CuInSe{sub 2} and its alloys, on a-Si and its alloys, and on CdTe. In the area of CuInSe{sub 2} and its alloys, EEC researchers have produced CuIn{sub 1-x}GaxSe{sub 2} films by selenization of elemental and alloyed films with H{sub 2}Se and Se vapor and by a wide variety of process variations employing co-evaporation of the elements. Careful design, execution and analysis of these experiments has led to an improved understanding of the reaction chemistry involved, including estimations of the reaction rate constants. Investigation of device fabrication has also included studies of the processing of the Mo, US and ZnO deposition parameters and their influence on device properties. An indication of the success of these procedures was the fabrication of a 15% efficiency CuIn{sub 1-x}GaxSe{sub 2} solar cell.

  8. Room temperature deposition of zinc oxide thin films by rf-magnetron sputtering for application in solar cells

    NASA Astrophysics Data System (ADS)

    Sanal, K. C.; Trujillo, R. R.; Nair, P. K.; Nair, M. T. S.

    2016-09-01

    Recent reports indicate that thin films of oxides of zinc: ZnO, Zn(O,S), or Zn-Mg-O, could be a better buffer component than CdS to provide an adequate band alignment with orthorhombic tin sulphide in thin lm solar cells. Thin films of ZnO were grown by rf-magnetron sputtering on different substrates at room temperature. Thin films of ZnO obtained by different deposition methods show hexagonal crystal structure, usually with a preferential orientation of (002) crystallographic planes parallel to the substrate surface. However, in the present study XRD patterns indicate that thicker ZnO films on glass substrates have preferential growth of (103) planes, while that on chemically deposited CdS or ZnS films preferential orientation of (002) planes persists. Bandgap of ZnO films increases from 3.2 eV to 3.4 eV when the chamber pressure used for deposition varies from 2.3 mTorr to 6 mTorr. ZnO films were incorporated in a solar cell structure stainless steel/SnS(cubic)/SnS(orthorhombic)/SnS(cubic)/CdS/ZnO/ZnO:Al. It showed open-circuit voltage of 0.318 V, short-circuit current density of 3.6 mA/cm2 and conversion efficiency of 0.82%.

  9. Indium tin oxide with titanium doping for transparent conductive film application on CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Sheng; Cheng, Huai-Ming; Hu, Hung-Chun; Li, Ying-Tse; Huang, Shi-Da; Yu, Hau-Wei; Pu, Nen-Wen; Liang, Shih-Chang

    2015-11-01

    In this study, Ti-doped indium tin oxide (ITO:Ti) thin films were fabricated using a DC-magnetron sputtering deposition method. The thin films were grown without introducing oxygen or heating the substrate, and no post-growth annealing was performed after fabrication. The thickness of the ITO:Ti thin films (350 nm) was controlled while increasing the sputtering power from 50 to 150 W. According to the results, the optimal optoelectronic properties were observed in ITO:Ti thin films grown at a sputtering power of 100 W, yielding a reduced resistivity of 3.2 × 10-4 Ω-cm and a mean high transmittance of 83% at wavelengths ranging from 400 to 800 nm. The optimal ITO:Ti thin films were used to fabricate a Cu(In,Ga)Se2 solar cell that exhibited a photoelectric conversion efficiency of 11.3%, a short-circuit current density of 33.1 mA/cm2, an open-circuit voltage of 0.54 V, and a fill factor of 0.64.

  10. Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells; January 28, 2010 -- January 31, 2011

    SciTech Connect

    Slafer, D.; Dalal, V.

    2012-03-01

    Final subcontract report for PV Incubator project 'Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells.' The goal of this program was to produce tandem Si cells using photonic bandgap enhancement technology developed at ISU and Lightwave Power that would have an NREL-verified efficiency of 7.5% on 0.25 cm{sup 2} area tandem junction cell on plastic substrates. This goal was met and exceeded within the timeframe and budget of the program. On smaller area cells, the efficiency was even higher, {approx}9.5% (not verified by NREL). Appropriate polymers were developed to fabricate photonic and plasmonic devices on stainless steel, Kapton and PEN substrates. A novel photonic-plasmon structure was developed which shows a promise of improving light absorption in thin film cells, a better light absorption than by any other scheme.

  11. Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Purohit, A.; Lal, C.; Nehra, S. P.; Dhaka, M. S.

    2016-05-01

    In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays an important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.

  12. Development of Commercial Technology for Thin Film Silicon Solar Cells on Glass: Cooperative Research and Development Final Report, CRADA Number CRD-07-209

    SciTech Connect

    Sopori, B.

    2013-03-01

    NREL has conducted basic research relating to high efficiency, low cost, thin film silicon solar cell design and the method of making solar cells. Two patents have been issued to NREL in the above field. In addition, specific process and metrology tools have been developed by NREL. Applied Optical Sciences Corp. (AOS) has expertise in the manufacture of solar cells and has developed its own unique concentrator technology. AOS wants to complement its solar cell expertise and its concentrator technology by manufacturing flat panel thin film silicon solar cell panels. AOS wants to take NREL's research to the next level, using it to develop commercially viable flat pane, thin film silicon solar cell panels. Such a development in equipment, process, and metrology will likely produce the lowest cost solar cell technology for both commercial and residential use. NREL's fundamental research capability and AOS's technology and industrial background are complementary to achieve this product development.

  13. Investigation of Cu2ZnSnS4 thin-film solar cells with carrier concentration gradient

    NASA Astrophysics Data System (ADS)

    Xu, Jiaxiong

    2016-11-01

    To investigate the effect of carrier concentration gradient on Cu2ZnSnS4 (CZTS) thin-film solar cells, the properties of CZTS solar cells were studied by numerical method. The photovoltaic performances of carrier concentration gradient CZTS solar cells were calculated by the solutions of Poisson's equation, continuity equation, and current density equation using AFors-Het v2.4 program. The carrier concentration gradient was changed to analyze its effect. Compared with CZTS solar cells without carrier concentration gradient, the photovoltaic performances of CZTS solar cells can be enhanced by using carrier concentration gradient absorber. The carrier concentration gradient can extend the distribution region of built-in electric field, which is beneficial to the drift of photo-generated carriers. However, the carrier concentration gradient also affects the recombination and series resistances of solar cells. When the defect density of CZTS layer is high, the photo-generated carriers are affected significantly by recombination, resulting in slight effect of carrier concentration gradient. Therefore, the defect density should be reduced to enhance the effect of carrier concentration gradient on improving conversion efficiency of CZTS thin-film solar cells.

  14. Transparent Conducting ZnO:B Thin Films Grown by Ultraviolet Light Assisted Metal Organic Chemical Vapor Deposition Using Triethylboron for Cu(In,Ga)Se2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Kobayashi, Taizo; Yamauchi, Kotaro; Mise, Takahiro; Nakada, Tokio

    2012-10-01

    High-efficiency cadmium-free Cu(In,Ga)Se2 (CIGS) thin-film solar cells have been fabricated using a zinc compound buffer layer deposited by the chemical bath deposition (CBD) process. However, the zinc compound buffer layers such as ZnS(O,OH) are prone to plasma-induced damage during the subsequent ZnO sputtering process. A process causing less damage such as metal-organic chemical vapor deposition (MOCVD) is thus required for ZnO-based transparent conducting oxide (TCO) layers. In the present work, the boron-doped zinc oxide (ZnO:B) films were grown by MOCVD using diethyl zinc (DEZ), H2O, and low-toxicity triethylboron (TEB). An UV-assisted MOCVD process was developed in order to reduce the resistivity of ZnO:B films. As a result, the resisitivity significantly decreased together with the increased electron mobility and carrier concentration. The comparison of performance was also carried out for the ZnS(O,OH)/CIGS solar cells with MOCVD-deposited ZnO:B and sputter-deposited ZnO:Al window layers.

  15. CIGS absorber layer with double grading Ga profile for highly efficient solar cells

    NASA Astrophysics Data System (ADS)

    Saadat, M.; Moradi, M.; Zahedifar, M.

    2016-04-01

    It is well-known that the band gap grading in CIGS solar cells is crucial for achieving highly efficient solar cells. We stimulate a CIGS solar cell and investigate the effects of the band gap grading on performance of the CIGS solar cell, where Ga/(Ga + In) ratio (GGI) at back (Cb) and front (Cf) of the absorber layer are considered constant. Our simulations show that by increasing the GGI at middle of CIGS absorber layer (Cm), the JSC decreases and VOC increases independent of the distance of the Cm from the back contact (Xm). For Cm lower than Cf, JSC increases and VOC decreases when the Xm shifts to the front of the CIGS layer. The behavior of JSC and VOC became reverse for the case of Cm greater than Cf. Almost in all of the structures, efficiency and FF have same behaviors. Our simulations show that the highest efficiency is obtained at Cm = 0.8 and Xm = 200 nm.

  16. Crystalline Indium Sulphide thin film by photo accelerated deposition technique

    NASA Astrophysics Data System (ADS)

    Dhanya, A. C.; Preetha, K. C.; Deepa, K.; Remadevi, T. L.

    2015-02-01

    Indium sulfide thin films deserve special attention because of its potential application as buffer layers in CIGS based solar cells. Highly transparent indium sulfide (InS) thin films were prepared using a novel method called photo accelerated chemical deposition (PCD). Ultraviolet source of 150 W was used to irradiate the solution. Compared to all other chemical methods, PCD scores its advantage for its low cost, flexible substrate and capable of large area of deposition. Reports on deposition of high quality InS thin films at room temperature are very rare in literature. The precursor solution was initially heated to 90°C for ten minutes and then deposition was carried out at room temperature for two hours. The appearance of the film changed from lemon yellow to bright yellow as the deposition time increased. The sample was characterized for its structural and optical properties. XRD profile showed the polycrystalline behavior of the film with mixed phases having crystallite size of 17 nm. The surface morphology of the films exhibited uniformly distributed honey comb like structures. The film appeared to be smooth and the value of extinction coefficient was negligible. Optical measurements showed that the film has more than 80% transmission in the visible region. The direct band gap energy was 2.47eV. This method is highly suitable for the synthesis of crystalline and transparent indium sulfide thin films and can be used for various photo voltaic applications.

  17. Development of copper sulfide/cadmium sulfide thin-film solar cells

    SciTech Connect

    Szedon, J. R.; Biter, W. J.; Dickey, H. C.

    1982-03-08

    The most important accomplishments during this period were to demonstrate and to elucidate further the complex effects that occur during the aging of Cu/sub 2/S/CdS thin-film solar cells in flowing wet oxygen. There are two distinct effects. At constant illumination, the short-circuit current of cells aged at room temperature consistently decreases with time. The second effect, related to diode opposing current, is more involved and may result from several competing mechanisms. Over the short term (approx. 4 to 5 hours), the magnitude of diode opposing current decreases. After approx. 20 hours of aging, opposing current generally returns to the level achieved after hydrogen annealing which immediately preceded the aging sequence. Optical measurements of the spectral transmission of the Cu/sub 2/S layers in a cell content have been made using a silicon detector epoxied to the back of a CdS cell after the copper foil substrate was removed. There is no significant change in Cu/sub 2/S transmission behavior for wavelengths ranging from 525 to 1000 nm during wet-oxygen aging for periods of 2 to 36 hours. This suggests that the decrease in J/sub SC/ at constant illumination, for the aging experiments in a flowing wet-oxygen ambient, arises because of changes in minority-carrier transport properties of the Cu/sub 2/S. Before developing a method for using an epoxied silicon detector to measure optical behavior of the Cu/sub 2/S layer, we explored the possibility of using a junction-containing wafer of silicon as a substrate for deposited CdS films. Some monolithic structures were successfully fabricated. Comparisons were made of CdS grain structure details in the junction detector area and in an adjacent metallized area.

  18. Electrochemically synthesized CuInSe2 thin films from non-aqueous electrolyte for solar cell applications

    NASA Astrophysics Data System (ADS)

    Londhe, Priyanka U.; Rohom, Ashwini B.; Lakhe, Manorama G.; Bhand, Ganesh R.; Chaure, Nandu B.

    2016-12-01

    Highly polycrystalline CuInSe2 (CIS) thin films have been electrodeposited from non-aqueous ethylene glycol (EG) solvent on fluorine-doped tin-oxide-coated glass substrates at 130 °C. The co-deposition potential for Cu, In and Se was optimized by using cyclic voltammetry. CIS layers have been electrodeposited from -1.1 V to -1.5 V versus the Ag/AgCl reference electrode. The effect of selenization on structural, morphological, optical and compositional properties has been studied extensively. Highly crystalline CIS thin films are electrodeposited for all reported growth potentials without post-annealing treatment. The Raman spectra of stoichiometric CIS thin films showed a dominant A1 mode with features receptive to the crystalline quality of the layers. Noticeable changes in the surface morphology and composition of films deposited at different deposition potential were observed. All CIS layers were void free, compact, uniform, and well adherent to the substrates with particle size ˜1-3 μm. Both as-deposited and selenized samples were Cu-rich, however, the composition of selenium remained closer to the ideal value, 50%. A typical solar cell prepared at -1.3 V measured V OC = 0.316 V, J SC = 26 mA, FF = 49, and η = 4.2, under illuminated conditions at 100 mW cm-2.

  19. The effect of dopant concentration on properties of transparent conducting Al-doped ZnO thin films for efficient Cu2ZnSnS4 thin-film solar cells prepared by electrodeposition method

    NASA Astrophysics Data System (ADS)

    Mkawi, E. M.; Ibrahim, K.; Ali, M. K. M.; Farrukh, M. A.; Mohamed, A. S.

    2015-11-01

    Al-doped ZnO (AZO) thin films were potentiostatically deposited on indium tin oxide substrates. The influence of the doping level of the ZnO:Al films was investigated. The results of the X-ray diffraction and scanning electron microscopy analysis revealed that the structural properties of the AZO films were found polycrystalline with a hexagonal wurtzite-type structure along the (002) plane. The grain size of the AZO films was observed as approximately 3 μm in the film doping with 4 mol% ZnO:Al concentration. The thin films also exhibited an optical transmittance as high as 90 % in the wavelength range of 100-1,000 nm. The optical band gap increased from 3.33 to 3.45 eV. Based on the Hall studies, the lowest resistivity (4.78 × 10-3 Ω cm) was observed in the film doping with 3 mol% ZnO:Al concentration. The sheet resistant, carrier concentration and Hall mobility values were found as 10.78 Ω/ square, 9.03 × 1018 cm-3 and 22.01 cm2/v s, respectively, which showed improvements in the properties of AZO thin films. The ZnO:Al thin films were used as a buffer layer in thin-film solar cells with the structure of soda-lime glass/Mo/Cu2ZnSnS4/ZnS/ZnO/Al grid. The best solar cell efficiency was 2.3 % with V OC of 0.430 V, J SC of 8.24 mA cm-2 and FF of 68.1 %.

  20. Carbon-Nanotube Conductive Layers for Thin-Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2005-01-01

    Thin, transparent layers comprising mats of carbon nanotubes have been proposed for providing lateral (that is, inplane) electrical conductivities for collecting electric currents from the front surfaces of the emitter layers of thin-film solar photovoltaic cells. Traditionally, thin, semitransparent films of other electrically conductive materials (usually, indium tin oxide, zinc oxide, or cadmium sulfide) have been used for this purpose. As in the cases of the traditional semitransparent conductive films, the currents collected by the nanotube layers would, in turn, be further collected by front metal contact stripes. Depending on details of a specific solar-cell design, the layer of carbon nanotubes would be deposited in addition to, or instead of, a semitransparent layer of one of these traditional conductive materials (see figure). The proposal is expected to afford the following advantages: The electrical conductivity of the carbon- nanotube layer would exceed that of the corresponding semitransparent layer of traditional electrically conductive material. The greater electrical conductivity of the carbon-nanotube layer would make it possible to retain adequate lateral electrical conductivity while reducing the thickness of, or eliminating entirely, the traditional semitransparent conductive layer. As a consequence of thinning or elimination of the traditional semitransparent conductive layer, less light would be absorbed, so that more of the incident light would be available for photovoltaic conversion. The greater electrical conductivity of the carbon-nanotube layer would make it possible to increase the distance between front metal contact stripes, in addition to (or instead of) thinning or eliminating the layer of traditional semitransparent conductive material. Consequently, the fraction of solar-cell area shadowed by front metal contact stripes would be reduced again, making more of the incident light available for photovoltaic conversion. The electrical

  1. Study of copper-free back contacts to thin film cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Viswanathan, Vijay

    The goals of this project are to study Cu free back contact alternatives for CdS/CdTe thin film solar cells, and to research dry etching for CdTe surface preparation before contact application. In addition, an attempt has been made to evaluate the stability of some of the contacts researched. The contacts studied in this work include ZnTe/Cu2Te, Sb2Te 3, and Ni-P alloys. The ZnTe/Cu2Te contact system is studied as basically an extension of the earlier work done on Cu2Te at USF. RF sputtering from a compound target of ZnTe and Cu2Te respectively deposits these layers on etched CdTe surface. The effect of Cu2Te thickness and deposition temperature on contact and cell performance will be studied with the ZnTe depositions conditions kept constant. C-V measurements to study the effect of contact deposition conditions on CdTe doping will also be performed. These contacts will then be stressed to high temperatures (70--100°C) and their stability with stress time is analyzed. Sb2Te3 will be deposited on glass using RF sputtering, to study film properties with deposition temperature. The Sb2Te 3 contact performance will also be studied as a function of the Sb 2Te3 deposition temperature and thickness. The suitability of Ni-P alloys for back contacts to CdTe solar cells was studied by forming a colloidal mixture of Ni2P in graphite paste. The Ni-P contacts, painted on Br-methanol etched CdTe surface, will be studied as a function of Ni-P concentration (in the graphite paste), annealing temperature and time. Some of these cells will undergo temperature stress testing to determine contact behavior with time. Dry etching of CdTe will be studied as an alternative for wet etching processes currently used for CdTe solar cells. The CdTe surface is isotropically etched in a barrel reactor in N2, Ar or Ar:O 2 ambient. The effect of etching ambient, pressure, plasma power and etch time on contact performance will be studied.

  2. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells

    NASA Astrophysics Data System (ADS)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, Junho; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-06-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the

  3. Synthesis and characterization of DC magnetron sputtered nano structured molybdenum thin films

    NASA Astrophysics Data System (ADS)

    Rondiya, S. R.; Rokade, A. V.; Jadhavar, A. A.; Pandharkar, S. M.; Kulkarni, R. R.; Karpe, S. D.; Diwate, K. D.; Jadkar, S. R.

    2016-04-01

    Molybdenum (Mo) thin films were deposited on corning glass (#7059) substrates using DC magnetron sputtering system. The effect of substrate temperature on the structural, morphology and topological properties have been investigated. Films were characterized by variety of techniques such as low angle x-ray diffraction (low angle XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM). The low angle XRD analysis revealed that the synthesized Mo films are nanocrystalline having cubic crystal structure with (110) preferential orientation. The microstructure of the deposited Mo thin films observed with FE-SEM images indicated that films are homogeneous and uniform with randomly oriented leaf shape morphology. The AFM analysis shows that with increase in substrate temperature the rms roughness of Mo films increases. The obtained results suggest that the synthesized nanostructured Mo thin films have potential application as a back contact material for high efficiency solar cells like CdTe, CIGS, CZTS etc.

  4. Low work function, stable thin films

    DOEpatents

    Dinh, Long N.; McLean, II, William; Balooch, Mehdi; Fehring, Jr., Edward J.; Schildbach, Marcus A.

    2000-01-01

    Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

  5. Device Physics of Nanoscale Interdigitated Solar Cells (Poster)

    SciTech Connect

    Metzger, W.; Levi, D.

    2008-05-01

    Nanoscale interdigitated solar cell device architectures are being investigated for organic and inorganic solar cell devices. Due to the inherent complexity of these device designs quantitative modeling is needed to understand the device physics. Theoretical concepts have been proposed that nanodomains of different phases may form in polycrystalline CIGS solar cells. These theories propose that the nanodomains may form complex 3D intertwined p-n networks that enhance device performance.Recent experimental evidence offers some support for the existence of nanodomains in CIGS thin films. This study utilizes CIGS solar cells to examine general and CIGS-specific concepts in nanoscale interdigitated solar cells.

  6. Anticipated performance of copper(indium,gallium)diselenide solar cells in the thin-film limit

    NASA Astrophysics Data System (ADS)

    Kanevce, Ana

    Thin-film solar cells are an excellent candidate for clean energy production, but the knowledge of device physics is still incomplete, especially in the low thickness limit. The goal of this work is to enhance the understanding of Cu(In,Ga)Se2 solar cells with submicron absorbers, which would lead to significantly lower production cost. The material usage and the deposition time can be significantly decreased, if the thickness could be reduced without significant efficiency loss. The main focus of this work is on GIGS cells with thin absorbers; (1) influence of parameter variation on device performance; (2) sensitivity to nonuniformities in key parameters, (3) potential of illumination from both sides of the cell, and (4) role of the buffer layer. As the cells become thinner, the distance between the back contact and the electric-field region narrows, or completely disappears. One of the main differences between thick and thin cells is the significance of back-contact recombination in thinner cells. A choice of the back-contact material or increased Ga towards the back are needed to avoid losses. In thin cells, there is a concern of increased sensitivity to nonuniformities. Fluctuations in defect density, band gap, thickness or doping affect the voltage. The low voltage area then influences the nonuniform cell performance. Thinner cells are more sensitive to thickness nonuniformities and therefore deposition methods that produce smooth absorbers are desirable for thin devices. In ultra-thin cells illumination from the back side can yield a significant output performance. If certain optimization steps are taken, the back side performance can approach that of the front side. In the case of a back-illuminated cell, the carrier generation occurs in the bulk, making it critical to lower back-contact recombination, as well as to provide good collection. Illumination with only low energy photons in cells with the commonly used CdS buffer layer causes distortion in the

  7. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  8. Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

    NASA Technical Reports Server (NTRS)

    Lathrop, J. W.

    1985-01-01

    If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

  9. Rigid Biopolymer Nanocrystal Systems for Controlling Multicomponent Nanoparticle Assembly and Orientation in Thin Film Solar Cells

    SciTech Connect

    Cha, Jennifer

    2016-10-31

    We have discovered techniques to synthesize well-defined DN conjugated nanostructures that are stable in a wide variety of conditions needed for DNA mediated assembly. Starting from this, we have shown that DNA can be used to control the assembly and integration of semiconductor nanocrystals into thin film devices that show photovoltaic effects.

  10. Preparation of monolithic cu(In0.7Ga0.3)Se2 nanopowders and subsequent fabrication of sintered CIGS films.

    PubMed

    Song, Bong-Geun; Jung, Jae Hee; Bae, Gwi-Nam; Park, Hyung-Ho; Park, Jong-Ku; Cho, So-Hye

    2013-09-01

    Cu(In,Ga)Se2 (CIGS) is a compound semiconductor and is one of the most attractive light-absorbing materials for use in thin film solar cells. Among the various approaches to prepare CIGS thin films, the powder process offers an extremely simple and materials-efficient method. Here, we report the mechano-chemical preparation of CIGS compound powders suitable for fabrication of CIGS films by a powder process. We found that the CIGS phase was formed from the elemental powders of Cu, In, and Se and liquid Ga using high energy milling process with a milling time as short as 40 min at 200 rpm due to a self-accelerating exothermic reaction. The morphology and size of the CIGS powders changed with a function of the milling speed (100-300 rpm), leading to an optimal condition of milling at 200 rpm for 120 min. We also found that it was difficult to obtain a monolithic phase of the CIGS powders without severe particle aggregation by mechano-chemical milling alone. Therefore, in combination with the milling, subsequent heat-treatment at 300 degrees C was performed, which successfully provided monolithic CIGS nanopowders suitable for powder process. When a thin film was fabricated from the monolithic CIGS nanopowders, a highly dense film with large crystalline grains was obtained. The CIGS film preserved its chemical composition of CuIn0.7Ga0.3Se2 after sintering as evidenced by Raman spectroscopy, EDS and SAED pattern of transmission electron microscopy. The film was also found suitable for a light absorbing layer of CIGS solar cells with its band gap energy of 1.14 eV evaluated by transmittance spectroscopy.

  11. Characterization of Sulfur Bonding in CdS:O Buffer Layers for CdTe-based Thin-Film Solar Cells.

    PubMed

    Duncan, Douglas A; Kephart, Jason M; Horsley, Kimberly; Blum, Monika; Mezher, Michelle; Weinhardt, Lothar; Häming, Marc; Wilks, Regan G; Hofmann, Timo; Yang, Wanli; Bär, Marcus; Sampath, Walajabad S; Heske, Clemens

    2015-08-05

    On the basis of a combination of X-ray photoelectron spectroscopy and synchrotron-based X-ray emission spectroscopy, we present a detailed characterization of the chemical structure of CdS:O thin films that can be employed as a substitute for CdS layers in thin-film solar cells. It is possible to analyze the local chemical environment of the probed elements, in particular sulfur, hence allowing insights into the species-specific composition of the films and their surfaces. A detailed quantification of the observed sulfur environments (i.e., sulfide, sulfate, and an intermediate oxide) as a function of oxygen content is presented, allowing a deliberate optimization of CdS:O thin films for their use as alternative buffer layers in thin-film photovoltaic devices.

  12. Using SiOx nano-films to enhance GZO Thin films properties as front electrodes of a-Si solar cells

    NASA Astrophysics Data System (ADS)

    Chang, Kow-Ming; Ho, Po-Ching; Yu, Shu-Hung; Hsu, Jui-Mei; Yang, Kuo-Hui; Wu, Chin-Jyi; Chang, Chia-Chiang

    2013-07-01

    One of the essential applications of transparent conductive oxides is as front electrodes for superstrate silicon thin-film solar cells. Textured TCO thin films can improve absorption of sunlight for an a-Si:H absorber during a single optical path. In this study, high-haze and low-resistivity bilayer GZO/SiOx thin films prepared using an atmospheric pressure plasma jet (APPJ) deposition technique and dc magnetron sputtering. The silicon subdioxide nano-film plays an important role in controlling the haze value of subsequent deposited GZO thin films. The bilayer GZO/SiOx (90 sccm) sample has the highest haze value (22.30%), the lowest resistivity (8.98 × 10-4 Ω cm), and reaches a maximum cell efficiency of 6.85% (enhanced by approximately 19% compared to a sample of non-textured GZO).

  13. Modification of opto-electronic properties of ZnO by incorporating metallic tin for buffer layer in thin film solar cells

    SciTech Connect

    Deepu, D. R.; Jubimol, J.; Kartha, C. Sudha; Louis, Godfrey; Vijayakumar, K. P.; Kumar, K. Rajeev

    2015-06-24

    In this report, the effect of incorporation of metallic tin (Sn) on opto-electronic properties of ZnO thin films is presented. ZnO thin films were deposited through ‘automated chemical spray pyrolysis’ (CSP) technique; later different quantities of ‘Sn’ were evaporated on it and subsequently annealed. Vacuum annealing showed a positive effect on crystallinity of films. Creation of sub band gap levels due to ‘Sn’ diffusion was evident from the absorption and PL spectra. The tin incorporated films showed good photo response in visible region. Tin incorporated ZnO thin films seem to satisfy the desirable criteria for buffer layer in thin film solar cells.

  14. Nano-structured CuO-Cu2O Complex Thin Film for Application in CH3NH3PbI3 Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Chen, Lung-Chieh; Chen, Cheng-Chiang; Liang, Kai-Chieh; Chang, Sheng Hsiung; Tseng, Zhong-Liang; Yeh, Shih-Chieh; Chen, Chin-Ti; Wu, Wen-Ti; Wu, Chun-Guey

    2016-09-01

    Nano-structured CuO-Cu2O complex thin film-based perovskite solar cells were fabricated on an indium tin oxide (ITO)-coated glass and studied. Copper (Cu) thin films with a purity of 99.995 % were deposited on an ITO-coated glass by magnetron reactive sputtering. To optimize the properties of the nano-structured CuO-Cu2O complex thin films, the deposited Cu thin films were thermally oxidized at various temperatures from 300 to 400 °C. A CH3NH3PbI3 perovskite absorber was fabricated on top of CuO-Cu2O complex thin film by a one-step spin-coating process with a toluene washing treatment. Following optimization, the maximum power conversion efficiency (PCE) exceeded 8.1 %. Therefore, the low-cost, solution-processed, stable nano-structured CuO-Cu2O complex thin film can be used as an alternative hole transport layer (HTL) in industrially produced perovskite solar cells.

  15. Nano-structured CuO-Cu2O Complex Thin Film for Application in CH3NH3PbI3 Perovskite Solar Cells.

    PubMed

    Chen, Lung-Chieh; Chen, Cheng-Chiang; Liang, Kai-Chieh; Chang, Sheng Hsiung; Tseng, Zhong-Liang; Yeh, Shih-Chieh; Chen, Chin-Ti; Wu, Wen-Ti; Wu, Chun-Guey

    2016-12-01

    Nano-structured CuO-Cu2O complex thin film-based perovskite solar cells were fabricated on an indium tin oxide (ITO)-coated glass and studied. Copper (Cu) thin films with a purity of 99.995 % were deposited on an ITO-coated glass by magnetron reactive sputtering. To optimize the properties of the nano-structured CuO-Cu2O complex thin films, the deposited Cu thin films were thermally oxidized at various temperatures from 300 to 400 °C. A CH3NH3PbI3 perovskite absorber was fabricated on top of CuO-Cu2O complex thin film by a one-step spin-coating process with a toluene washing treatment. Following optimization, the maximum power conversion efficiency (PCE) exceeded 8.1 %. Therefore, the low-cost, solution-processed, stable nano-structured CuO-Cu2O complex thin film can be used as an alternative hole transport layer (HTL) in industrially produced perovskite solar cells.

  16. Approaches to Encapsulation of Flexible CIGS Cells

    SciTech Connect

    Olsen, Larry C.; Gross, Mark E.; Graff, Gordon L.; Kundu, Sambhu N.; Chu, Xi; Lin, Steve

    2008-07-16

    Thin-film solar cells based on CIGS are being considered for large scale power plants as well as building integrated photovoltaic (BIPV) applications. Past studies indicate that CIGS cells degrade rapidly when exposed to moisture. As a result, an effective approach to encapsulation is required for CIGS cells to satisfy the international standard IEC 61646. CIGS modules fabricated for use in large power plants can be encapsulated with glass sheets on the top and bottom surfaces and can be effectively sealed around the edges. In the case of BIPV applications, however, it is desirable to utilize CIGS cells grown on flexible substrates, both for purposes of achieving reduced weight and for cases involving non-flat surfaces. For these cases, approaches to encapsulation must be compatible with the flexible substrate requirement. Even in the case of large power plants, the glass-to-glass approach to encapsulation may eventually be considered too costly. We are investigating encapsulation of flexible CIGS cells by lamination. Sheets of PET or PEN coated with multilayer barrier coatings are used to laminate the flexible cells. Results are discussed for laminated cells from two CIGS manufacturers. In both cases, the cell efficiency decreases less than 10% after 1000 hours of exposure to an environment of 85C/85%RH. This paper discusses these two approaches, reviews results achieved with cells and mini-modules fabricated by the former Shell Solar, Industries (SSI) stressed at 60C/90%RH (60/90), and recent studies of encapsulated IEC cells subjected to an environment of 85ºC/85%RH (85/85).

  17. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  18. Effective Light Trapping in Thin Film Silicon Solar Cells with Nano- and Microscale Structures on Glass Substrate.

    PubMed

    Bong, Sungjae; Ahn, Shihyun; Anh, Le Huy Tuan; Kim, Sunbo; Park, Hyeongsik; Shin, Chonghoon; Park, Jinjoo; Lee, Younjung; Yi, Junsin

    2016-05-01

    For thin film silicon-based solar cells, effective light trapping at a broad range of wavelengths (400-1100 nm) is necessary. Normally, etching is only carried out with TCOs, such as SnO2:F and impurity doped ZnO, to form nano-sized craters in the surface morphology to confer a light trapping effect. However, in this study, prior to ZnO:Al etching, periodic structures on the glass substrates were made by photolithography and wet etching to increase the light scattering and internal reflection. The use of periodic structures on the glass substrate resulted in higher haze ratios in the range from 550 nm to 1100 nm, which is the optical absorption wavelength region for thin film silicon solar cells, than obtained by simple ZnO:Al etching. The periodically textured glass with micro-sized structures compensates for the low haze ratio at the middle and long wavelengths of wet etched ZnO:Al. ZnO:Al was deposited on the periodically textured glass, after which the ZnO:Al surface was also etched randomly using a mixed acid solution to form nano-sized craters. The thin film silicon solar cells with 350-nm-thick amorphous silicon absorber layer deposited on the periodic structured glass and etched ZnO:Al generated up to 10.68% more photocurrent, with 11.2% increase of the conversion efficiency compared to the cell deposited on flat glass and etched ZnO:Al.

  19. Sodium-Doped Molybdenum Targets for Controllable Sodium Incorporation in CIGS Solar Cells

    SciTech Connect

    Mansfield, L. M.; Repins, I. L.; Glynn, S.; Carducci, M. D.; Honecker, D. M.; Pankow, J.l W.; Young, M. R.; DeHart, C.; Sundaramoorthy, R.; Beall, C. L.; To, B.

    2011-01-01

    The efficiency of Cu(In, Ga)Se{sub 2} (CIGS) solar cells is enhanced when Na is incorporated in the CIGS absorber layer. This work examines Na incorporation in CIGS utilizing Na-doped Mo sputtered from targets made with sodium molybdate-doped (MONA) powder. Mo:Na films with varying thicknesses were sputtered onto Mo-coated borosilicate glass (BSG) or stainless steel substrates for CIGS solar cells. By use of this technique, the Na content of CIGS can be varied from near-zero to higher than that obtained from a soda-lime glass (SLG) substrate. Targets and deposition conditions are described. The doped Mo films are analyzed, and the resulting devices are compared to devices fabricated on Mo-coated SLG as well as Mo-coated BSG with NaF. Completed devices utilizing MONA exceeded 15.7% efficiency without anti-reflective coating, which was consistently higher than devices prepared with the NaF precursor. Strategies for minimizing adhesion difficulties are presented.

  20. Sodium-Doped Molybdenum Targets for Controllable Sodium Incorporation in CIGS Solar Cells: Preprint

    SciTech Connect

    Mansfield, L. M.; Repins, I. L.; Glynn, S.; Carducci, M. D.; Honecker, D. M.; Pankow, J.; Young, M.; DeHart, C.; Sundaramoorthy, R.; Beall, C. L.; To, B.

    2011-07-01

    The efficiency of Cu(In,Ga)Se2 (CIGS) solar cells is enhanced when Na is incorporated in the CIGS absorber layer. This work examines Na incorporation in CIGS utilizing Na-doped Mo sputtered from targets made with sodium molybdate-doped (MONA) powder. Mo:Na films with varying thicknesses were sputtered onto Mo-coated borosilicate glass (BSG) or stainless steel substrates for CIGS solar cells. By use of this technique, the Na content of CIGS can be varied from near-zero to higher than that obtained from a soda-lime glass (SLG) substrate. Targets and deposition conditions are described. The doped Mo films are analyzed, and the resulting devices are compared to devices fabricated on Mo-coated SLG as well as Mo-coated BSG with NaF. Completed devices utilizing MONA exceeded 15.7% efficiency without anti-reflective coating, which was consistently higher than devices prepared with the NaF precursor. Strategies for minimizing adhesion difficulties are presented.

  1. Investigation of Some Transparent Metal Oxides as Damp Heat Protective Coating for CIGS Solar Cells: Preprint

    SciTech Connect

    Pern, F. J.; Yan, F.; Zaaunbrecher, B.; To, B.; Perkins, J.; Noufi, R.

    2012-10-01

    We investigated the protective effectiveness of some transparent metal oxides (TMO) on CIGS solar cell coupons against damp heat (DH) exposure at 85oC and 85% relative humidity (RH). Sputter-deposited bilayer ZnO (BZO) with up to 0.5-um Al-doped ZnO (AZO) layer and 0.2-um bilayer InZnO were used as 'inherent' part of device structure on CdS/CIGS/Mo/SLG. Sputter-deposited 0.2-um ZnSnO and atomic layer deposited (ALD) 0.1-um Al2O3 were used as overcoat on typical BZO/CdS/CIGS/Mo/SLG solar cells. The results were all negative -- all TMO-coated CIGS cells exhibited substantial degradation in DH. Combining the optical photographs, PL and EL imaging, SEM surface micro-morphology, coupled with XRD, I-V and QE measurements, the causes of the device degradations are attributed to hydrolytic corrosion, flaking, micro-cracking, and delamination induced by the DH moisture. Mechanical stress and decrease in crystallinity (grain size effect) could be additional degrading factors for thicker AZO grown on CdS/CIGS.

  2. Selective structuring of multi-layer functional thin films using a laser-induced shockwave delamination process

    NASA Astrophysics Data System (ADS)

    Ehrhardt, M.; Lorenz, P.; Bayer, L.; Molpeceres, C.; Ramirez, C. Antonio Herrera; Zimmer, K.

    2016-03-01

    The laser assisted micro structuring of thin films especially for electronic applications without influence the functionality of the multi-layer system e.g. due to melting products is a challenge for the laser micro machining techniques. The P2 scribing of copper indium gallium selenide (CIGS) solar cells on stainless steel carrier foil was studied using shockwave- induced film delamination (SWIFD) patterning. The delamination process is induced by a shock wave generated by the laser ablation of the rear side of the carrier foil. In the present study UV nanosecond laser pulses provided by a KrF excimer laser were used to induce the SWIFD process. The morphology and size of the achieved thin-film structures were studied in dependence on various laser irradiation parameters by optical and scanning electron microscopy (SEM). Furthermore, the materials composition after the laser patterning was analyzed by energy dispersive X-ray spectroscopy (EDX). The temporal sequences of processes involved in the SWIFD process were analyzed with high speed shadowgraph experiments. The results of the present study shows that in dependence on the laser parameter used a large process window exist in which the CIGS thin film can be removed from the substrate without visible thermal modification of the CIGS thin film.

  3. Design of optimal buffer layers for CuInGaSe2 thin-film solar cells(Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lordi, Vincenzo; Varley, Joel B.; He, Xiaoqing; Rockett, Angus A.; Bailey, Jeff; Zapalac, Geordie H.; Mackie, Neil; Poplavskyy, Dmitry; Bayman, Atiye

    2016-09-01

    Optimizing the buffer layer in manufactured thin-film PV is essential to maximize device efficiency. Here, we describe a combined synthesis, characterization, and theory effort to design optimal buffers based on the (Cd,Zn)(O,S) alloy system for CIGS devices. Optimization of buffer composition and absorber/buffer interface properties in light of several competing requirements for maximum device efficiency were performed, along with process variations to control the film and interface quality. The most relevant buffer properties controlling performance include band gap, conduction band offset with absorber, dopability, interface quality, and film crystallinity. Control of an all-PVD deposition process enabled variation of buffer composition, crystallinity, doping, and quality of the absorber/buffer interface. Analytical electron microscopy was used to characterize the film composition and morphology, while hybrid density functional theory was used to predict optimal compositions and growth parameters based on computed material properties. Process variations were developed to produce layers with controlled crystallinity, varying from amorphous to fully epitaxial, depending primarily on oxygen content. Elemental intermixing between buffer and absorber, particularly involving Cd and Cu, also is controlled and significantly affects device performance. Secondary phase formation at the interface is observed for some conditions and may be detrimental depending on the morphology. Theoretical calculations suggest optimal composition ranges for the buffer based on a suite of computed properties and drive process optimizations connected with observed film properties. Prepared by LLNL under Contract DE-AC52-07NA27344.

  4. Self-assembly method for controlling spatial frequency response of plasmonic back reflectors in organic thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Okamoto, Takayuki; Shinotsuka, Kei; Kawamukai, Etsuko; Ishibashi, Koji

    2017-01-01

    We propose a novel colloidal lithography technique that uses a mixture of colloidal particles with a few different diameters. This technique can be used for fabricating quasi-random nanostructures whose k-space spectra can be easily controlled by using an appropriate combination of particles. We introduced such nanostructures into the back reflectors of organic thin-film solar cells, where they serve as plasmonic back reflectors for recycling the nonabsorbed transmitted light into surface plasmons. The obtained photon-to-current efficiency was enhanced by 14-20% compared with that of a flat cell.

  5. Thin film CdTe solar cells with an absorber layer thickness in micro- and sub-micrometer scale

    NASA Astrophysics Data System (ADS)

    Bai, Zhizhong; Yang, Jun; Wang, Deliang

    2011-10-01

    CdTe thin film solar cell with an absorber layer as thin as 0.5 μm was fabricated. An efficiency of 7.9% was obtained for a 1-μm-thick CdTe solar cell. An increased intensity of deep recombination states in the band gap, which was responsible for the reduced open-circuit voltage and fill factor for ultra-thin solar cells, was induced due to the not-well-developed polycrystalline CdTe microstructure and the CdS/CdTe heterojunction and the presence of Cu in the back contact. The experimental results presented in this study demonstrated that 1-μm-thick absorber layer is thick enough to fabricate CdTe solar cell with a decent efficiency.

  6. Solution-processed highly efficient Cu2ZnSnSe4 thin film solar cells by dissolution of elemental Cu, Zn, Sn, and Se powders.

    PubMed

    Yang, Yanchun; Wang, Gang; Zhao, Wangen; Tian, Qingwen; Huang, Lijian; Pan, Daocheng

    2015-01-14

    Solution deposition approaches play an important role in reducing the manufacturing cost of Cu2ZnSnSe4 (CZTSe) thin film solar cells. Here, we present a novel precursor-based solution approach to fabricate highly efficient CZTSe solar cells. In this approach, low-cost elemental Cu, Zn, Sn, and Se powders were simultaneously dissolved in the solution of thioglycolic acid and ethanolamine, forming a homogeneous CZTSe precursor solution to deposit CZTSe nanocrystal thin films. Based on high-quality CZTSe absorber layer, pure selenide CZTSe solar cell with a photoelectric conversion efficiency of 8.02% has been achieved without antireflection coating.

  7. High-efficiency, thin-film solar cells. Annual subcontractor report, 1 July 1991--30 June 1992

    SciTech Connect

    Gale, R.P.

    1994-01-01

    This report describes work on a 3-year research program to investigate thin-film GaAs/GaInP cells using the cleavage of lateral epitaxial film for transfer (CLEFT) technique, and to determine the process to enable overgrowth of GaAs films using organometallic chemistry. Application of the CLEFT thin-film technique to GaInP/GaAs solar cells and organometallic overgrowth was investigated. A problem of alloy contamination was identified and controlled, leading to higher quality layers. Solar cell structures were grown and fabricated using previously determined growth parameters for GaAs and GaInP. With the improved materials developed significant improvements were made in solar cell performance. Conditions for in-situ overgrowth by organometallic chemical vapor deposition (OMCVD) were determined and continuous GaAs layers were grown over a separation mask layer. The layers were successfully separated from their substrate using the CLEFT process, demonstrating the application of overgrowth using OM chemistry with HCl.

  8. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications.

    PubMed

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-03

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation &immersion (E &I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm(2)) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  9. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  10. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    PubMed Central

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-01-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance. PMID:26631493

  11. A light-trapping strategy for nanocrystalline silicon thin-film solar cells using three-dimensionally assembled nanoparticle structures.

    PubMed

    Ha, Kyungyeon; Jang, Eunseok; Jang, Segeun; Lee, Jong-Kwon; Jang, Min Seok; Choi, Hoseop; Cho, Jun-Sik; Choi, Mansoo

    2016-02-05

    We report three-dimensionally assembled nanoparticle structures inducing multiple plasmon resonances for broadband light harvesting in nanocrystalline silicon (nc-Si:H) thin-film solar cells. A three-dimensional multiscale (3DM) assembly of nanoparticles generated using a multi-pin spark discharge method has been accomplished over a large area under atmospheric conditions via ion-assisted aerosol lithography. The multiscale features of the sophisticated 3DM structures exhibit surface plasmon resonances at multiple frequencies, which increase light scattering and absorption efficiency over a wide spectral range from 350-1100 nm. The multiple plasmon resonances, together with the antireflection functionality arising from the conformally deposited top surface of the 3D solar cell, lead to a 22% and an 11% improvement in power conversion efficiency of the nc-Si:H thin-film solar cells compared to flat cells and cells employing nanoparticle clusters, respectively. Finite-difference time-domain simulations were also carried out to confirm that the improved device performance mainly originates from the multiple plasmon resonances generated from three-dimensionally assembled nanoparticle structures.

  12. Electron and proton radiation effects on GaAs and CuInSe2 thin film solar cells

    NASA Astrophysics Data System (ADS)

    Burgess, R. M.; Chen, W. S.; Devaney, W. E.; Doyle, D. H.; Kim, N. P.

    The effects of proton and electron radiation on the performances of GaAs and CuInSe2/CdZnS (CIS) thin-film solar cells are evaluated. Bare cells (i.e., with no coverglass) were exposed to several energies of electron and proton radiation, and their performances were monitored by illuminated I-V curves, dark I-V curves, and spectral response measurements at different fluence levels. These experiments reconfirm that no measurable damage occurs to CIS solar cells when exposed to 1 and 2 MeV electrons to a total fluence of 5.0 x 10 to the 15th/sq cm. For proton irradiations, the results indicate that CIS cells are more radiation resistant than GaAs cells, by a factor of ten, when compared at the same energy levels. Comparison of the electron and proton irradiation results to those reported in the literature shows that the thin-film GaAs solar cells are as radiation resistant as other GaAs bulk cells at 1.0 MeV protons and are more radiation resistant at both the 1.0-MeV electron and 200-keV proton energies.

  13. Comparison between periodic and stochastic parabolic light trapping structures for thin-film microcrystalline Silicon solar cells.

    PubMed

    Peters, M; Battaglia, C; Forberich, K; Bläsi, B; Sahraei, N; Aberle, A G

    2012-12-31

    Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a scattering structure, characterized by an atomic force microscope. This structure is used for light trapping in thin-film microcrystalline silicon solar cells. Very good agreement is found in a first comparison between simulation and experimental results. The geometrical parameters of the stochastic structure are varied and it is found that the light trapping mainly depends on the aspect ratio (length/height). Furthermore, the maximum possible light trapping with this kind of stochastic structure geometry is investigated. In a second step, the stochastic structure is analysed and typical geometrical features are extracted, which are then arranged in a periodic structure. Investigating the light trapping properties of the periodic structure, we find that it performs very similar to the stochastic structure, in agreement with reports in literature. From the obtained results we conclude that a potential advantage of periodic structures for PV applications will very likely not be found in the absorption enhancement in the solar cell material. However, uniformity and higher definition in production of these structures can lead to potential improvements concerning electrical characteristics and parasitic absorption, e.g. in a back reflector.

  14. Light trapping efficiency of periodic and quasiperiodic back-reflectors for thin film solar cells: A comparative study

    NASA Astrophysics Data System (ADS)

    Micco, A.; Ricciardi, A.; Pisco, M.; La Ferrara, V.; Mercaldo, L. V.; Delli Veneri, P.; Cutolo, A.; Cusano, A.

    2013-08-01

    Recently, great efforts have been carried out to design optimized metallic nano-grating back-reflectors to improve the light absorption in thin film solar cells. In this work, we compare the performances of deterministic aperiodic backreflectors in the form of 1-D nanogratings based on the generalized Fibonacci deterministic aperiodic sequence with a standard periodic one. The case of study here analyzed relies on a realistic solar cell model, where light absorption is evaluated only in the intrinsic region of an amorphous silicon P-I-N junction. We found that the results of comparison are strongly influenced by the amorphous silicon extinction coefficient within the near-infrared wavelength range, where most photonic-plasmonic modes (responsible for the light absorption enhancement typically observed when structured metal nanogratings are employed) are excited. In particular, with device-grade hydrogenated amorphous silicon, we demonstrate that Fibonacci-like backreflectors are able to provide an absorption enhancement of about 4% and 20% with respect to periodic and flat metallic backreflectors, respectively. We also found that aperiodic gratings guarantee better results in terms of robustness to the incident angle of the incoming radiation. Overall, our results confirm that aperiodic geometries are effectively able to offer some intriguing perspectives to enhance light trapping capability in thin film solar cells especially thanks to the large set of patterns employable to enable a proper design of resonant modes number and their spectral locations.

  15. A comparative study on the performance of Kesterite based thin film solar cells using SCAPS simulation program

    NASA Astrophysics Data System (ADS)

    Simya, O. K.; Mahaboobbatcha, A.; Balachander, K.

    2015-06-01

    A comparative study of thin film solar cells based on CZTS, CZTSe, and CZTSSe (Copper Zinc Tin Sulphur Selenium) absorbers layers were simulated with Cadmium Sulphide (CdS) as buffer layer and Zinc Oxide (ZnO) as window layer using a solar cell capacitance simulator (SCAPS). The influences of series resistance, band to band recombination, defects and interfaces, thickness of (CZTS|CZTSe|CZTSSe) absorber layer, (CdS) buffer layer and transparent conductive oxide layer (ZnO) on the photovoltaic cell parameters were studied in detail. Improvements in efficiency were achieved by changing the back contact metal work function (BMWF) and choosing the flat band option in SCAPS software. Based on the best possible optimisation, an efficiency (η) of 12.03%, 13.16% and 15.77% were obtained for CZTS, CZTSe, and CZTSSe respectively. The performance of thin film photovoltaic devices (TFPV), for Mo back contact before optimisation and the SCAPS simulated values (flat band) after optimisation were described in detail to have in-depth understanding for better design of experiments (DOE) to obtain high efficiency solar cells.

  16. CRADA with United Solar Technologies and Pacific Northwest Laboratory (PNL-021): Thin film materialsfor low-cost high performance solar concentrators

    NASA Astrophysics Data System (ADS)

    Martin, P. M.; Affinito, J. D.; Gross, M. E.; Bennett, W. D.

    1995-03-01

    The objectives of this project were to develop and evaluate promising low-cost dielectric and polymer-protected thin-film reflective metal coatings to be applied to preformed continuously-curved solar reflector panels to enhance their solar reflectance, and to demonstrate protected solar reflective coatings on preformed solar concentrator panels. The opportunity for this project arose from a search by United Solar Technologies (UST) for organizations and facilities capable of applying reflective coatings to large preformed panels. PNL was identified as being uniquely qualified to participate in this collaborative project.

  17. Preparations for low-cost silica substrate of CIGS solar cell

    NASA Astrophysics Data System (ADS)

    Hsu, Ming-Seng; Chang, Chung Chih; Cheng, Hsiang Hshi; Ouyang, Yueh; Der Sheu, Shinn

    2008-08-01

    The production of CuInGaSe2 (CIGS) solar cell is based on vacuum processes, which requires a high manufacturing temperature and high cost. Our result show a simple method has been developed to prepare the silica substrates of CIGS solar cell. It's synthesized by sol-gel process from tetraethylorthosilicate (TEOS), methanol (CH3OH) and pure water (both ion-exchange and distillation) in the presence of ammonia as catalyst. The preparation procedure was elaborated as the flexible sequence to control chemical composition and properties of the particles in sol-gel-derived silica substrate. The morphology, particle size, and size distribution of CIGS substrate were characterized with dynamic light scattering (DLS) and atomic force microscopy (AFM). The results of AFM morphology and statistic evidence we find an easy way, non-vacuum and low temperature processes, to successfully prepare the CIGS solar cell substrates with surface roughness below 3 nm. It is powerful the advance study in low cost solar cell.

  18. Fabrication of Cu2Zn(Sn,Si)S4 thin films using a two-step method for solar cell applications

    NASA Astrophysics Data System (ADS)

    Xu, Jiaxiong; Liu, Yaqun; Yang, Yuanzheng

    2016-09-01

    To explore Cu2ZnSnS4-based materials for solar cell applications, for the first time, Cu2Zn(Sn,Si)S4 thin films were fabricated using a two-step method that consists of sputtering and post-sulfurization. The films were characterized and then incorporated into solar cells. X-ray diffraction and Raman spectroscopy revealed the formation of Cu2Zn(Sn,Si)S4 structure with traces of a secondary phase after sulfurization treatments. The degree of sulfurization was enhanced as the temperature was increased. In addition, these techniques revealed that there was no silicon or silicide phase present. The Si/Sn atomic ratio was 0.04-0.10. The thin films exhibited Cu-poor and Zn-rich characteristics and high absorption coefficients. The direct optical band gap of the thin films ranged between 1.42 and 1.52 eV. Heterojunction solar cells (glass/Mo/Cu2Zn(Sn,Si)S4/CdS/i-ZnO/ZnO:Al/Al) were fabricated and exhibited the highest conversion efficiency of 0.427%. This study showed the feasibilities of fabricating Cu2Zn(Sn,Si)S4 thin films by a two-step method and using Cu2Zn(Sn,Si)S4 thin films as an absorber layer within a solar cell.

  19. Improved Energy Conversion Efficiency of TiO2 Thin Films Modified with Ta2O5 in Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Kao, Ming-Cheng; Chen, Hone-Zern; Young, San-Lin

    2013-01-01

    Tantalum-doped TiO2 thin films [(TiO2)1-x(Ta2O5)x, x=0-0.8%] were prepared on fluorine-doped tin oxide (FTO)-coated substrates by sol-gel technology for uses in dye-sensitized solar cells (DSSCs). The effects of Ta content on the growth and properties of the TiO2 thin films were investigated. The crystallization and microstructures of the thin films were examined by X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller analyses. The performance of DSSCs based on Ta-doped TiO2 thin films was also studied. From the obtained results, the increases in Jsc and Voc may be due to the increased electron concentration of TiO2 thin film and the flat-band potential of the TiO2 shifted by tantalum doping, respectively. The optimum properties of DSSCs of Voc=0.68 V, Jsc=7.84 mA/cm2, FF=45.1%, and η=2.4% were obtained using the Ta-doped TiO2 thin film with x=0.5%.

  20. Deep level transient spectroscopy investigation of deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact

    NASA Astrophysics Data System (ADS)

    Wang, Zhao; Li, Bing; Zheng, Xu; Xie, Jing; Huang, Zheng; Liu, Cai; Feng, Liang-Huan; Zheng, Jia-Gui

    2010-02-01

    Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep defects in the CdTe thin film. With the help of deep level transient spectroscopy (DLTS), we study the deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact. One hole trap and one electron trap are observed. The hole trap H1, localized at Ev + 0.128 eV, originates from the vacancy of Cd (VCd). The electron trap E1, found at Ec -0.178 eV, is considered to be correlated with the interstitial Cuj+ in CdTe.

  1. Controllable thin film crystal growth of a novel squaraine molecule in organic solar cells

    NASA Astrophysics Data System (ADS)

    Conrad, Brad; Spencer, Susan; Bougher, Cortney; Brown, Jesse; Kelley, Kyle; Heaphy, Patrick; Murcia, Victor; Gallivan, Cameron; Monfette, Amber; Andersen, John; Cody, Jeremy; Coffey, Tonya; Collison, Christopher

    2014-03-01

    We will discuss the formation, structures, and properties of squarine and squarine-PCBM blend thin-films using Atomic Force Microscopy, electrical characterization, UV-VIS-NIR, and Thin-film Xray Diffraction. Film properties are inferred from spectroscopic measurements and are correlated with crystallinity as determined by TFXRD and AFM. A comprehensive explanation of DiPSQ(OH)2 structures is provided and related to measured efficiencies up to 4.3. By controlling the blend ratio and other fabrication conditions, crystalline regions of higher mobility can be developed so as to make significant gains in power conversion efficiency, necessary to achieve long term goals for commercially viable NIR-active OPV devices. AppState Office of Student Research; Synthesis by Cody group. BRC thanks ORAU Junior Faculty Enhancement Award. SDS, CPG and AM thank DOE Award number DE-FG36-08GO88110. CJC and JAC thank NSF award number CBET-1236372.

  2. Nanostructure-Preserved Hematite Thin Film for Efficient Solar Water Splitting.

    PubMed

    Kim, Jae Young; Youn, Duck Hyun; Kim, Ju Hun; Kim, Hyun Gyu; Lee, Jae Sung

    2015-07-01

    High-temperature annealing above 700 °C improves the activity of photoelectrochemical water oxidation by hematite photoanodes by increasing its crystallinity. Yet, it brings severe agglomeration of nanostructured hematite thin films and deteriorates electrical conductivity of the transparent conducting oxide (TCO) substrate. We report here that the nanostructure of the hematite and the conductivity of TCO could be preserved, while the high crystallinity is attained, by hybrid microwave annealing (HMA) utilizing a graphite susceptor for efficient microwave absorption. Thus, the hematite thin-film photoanodes treated by HMA record 2 times higher water oxidation photocurrents compared to a conventional thermal-annealed photoanode. The enhanced performance can be attributed to the synergistic effect of a smaller feature size of nanostructure-preserved hematite and a good electrical conductivity of TCO. The method could be generally applied to the fabrication of efficient photoelectrodes with small feature sizes and high crystallinity, which have been mutually conflicting requirements with conventional thermal annealing processes.

  3. Absorptive carbon nanotube electrodes: consequences of optical interference loss in thin film solar cells.

    PubMed

    Tait, Jeffrey G; De Volder, Michaël F L; Cheyns, David; Heremans, Paul; Rand, Barry P

    2015-04-28

    A current bottleneck in the thin film photovoltaic field is the fabrication of low cost electrodes. We demonstrate ultrasonically spray coated multiwalled carbon nanotube (CNT) layers as opaque and absorptive metal-free electrodes deposited at low temperatures and free of post-deposition treatment. The electrodes show sheet resistance as low as 3.4 Ω □(-1), comparable to evaporated metallic contacts deposited in vacuum. Organic photovoltaic devices were optically simulated, showing comparable photocurrent generation between reflective metal and absorptive CNT electrodes for photoactive layer thickness larger than 600 nm when using archetypal poly(3-hexylthiophene) (P3HT) : (6,6)-phenyl C61-butyric acid methyl ester (PCBM) cells. Fabricated devices clearly show that the absorptive CNT electrodes display comparable performance to solution processed and spray coated Ag nanoparticle devices. Additionally, other candidate absorber materials for thin film photovoltaics were simulated with absorptive contacts, elucidating device design in the absence of optical interference and reflection.

  4. Effects of Voltage-Bias Annealing on Metastable Defect Populations in CIGS and CZTSe Solar Cells

    SciTech Connect

    Harvey, Steven P.; Johnston, Steve; Teeter, Glenn

    2016-11-21

    We report on voltage-bias annealing (VBA) experiments performed on CIGS and CZTSe solar cells. In these experiments, completed devices were annealed at moderate temperatures and subsequently quenched with continuously applied voltage bias. These treatments resulted in substantial reversible changes in device characteristics. Photovoltaic (PV) conversion efficiency of the CIGS device varied from below 3% to above 15%, with corresponding changes in CIGS hole density from ~1014 cm-3 to ~1017 cm-3. In the CZTSe device, open-circuit voltage varied from 289 meV to 446 meV, caused by an approximately factor of fifty change in the CZTSe hole density. We interpret these findings in terms of reversible changes to the metastable point-defect populations that control key properties in these materials. Implications for optimization of PV materials and connections to long-term stability of PV devices are discussed.

  5. UV micro-imprint patterning for tunable light trapping in p-i-n thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Yanfeng; Zhang, Xiaodan; Han, Bing; Bai, Lisha; Zhao, Huixu; Yang, Fu; Liang, Junhui; Huang, Qian; Chen, Xinliang; Zhao, Ying

    2015-11-01

    In this paper, we used UV micro-imprint lithography periodic patterning combined with self-textured BZO films with a wide range of texture distributions for light trapping in thin-film silicon solar cells. It was found that the feature size of the periodic textures has a significant influence on the light trapping capacity of the glass substrate and the external quantum efficiency (EQE) of microcrystalline silicon (μc-Si:H) solar cells. Microcrystalline silicon solar cells, deposited on periodic textures of 5 μm, showed an improved photocurrent density without any loss in the open-circuit voltage and fill factor; hence, resulting in an overall efficiency increase of 6.28%.

  6. Effect of Sulfurization Temperature on Solution-Processed Cu2ZnSnS4 Thin Films.

    PubMed

    Park, Si-Nae; Sung, Shi-Joon; Son, Dae-Ho; Kim, Dae-Hwan; Sim, Jun-Hyoung; Kang, Jin-Kyu

    2015-03-01

    Cu2ZnSnS4 (CZTS) solar cells are attracting significant attention as an alternative to CIGS (Culn1-xGa(x)S2) solar cells because of the non-toxic and inexpensive constituent elements of CZTS. Recently, solution-based deposition methods are being developed because they have advantages such as suitability for use in large-area deposition, high-throughput manufacturing, and a very short energy payback time with drastically lower manufacturing costs. In this work, we fabricated solution-based CZTS thin films and investigated them in order to observe the effects of sulfurization temperature on CZTS thin films. We confirmed the grain size, morphology, chemical composition, crystallinity, and electrical properties of CZTS thin films depending on various sulfurization temperatures.

  7. Defect engineering in solar cell manufacturing and thin film solar cell development

    SciTech Connect

    Sopori, B.L.

    1995-08-01

    During the last few years many defect engineering concepts were successfully applied to fabricate high efficiency silicon solar cells on low-cost substrates. Some of the research advances are described.

  8. Light coupling into the Whispering Gallery Modes of a fiber array thin film solar cell for fixed partial Sun tracking

    PubMed Central

    Mariano, Marina; Rodríguez, Francisco J.; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

    2014-01-01

    We propose the use of whispering gallery mode coupling in a novel configuration based on implementing a thin film cell on the backside of an array of parallel fibers. We performed numerical calculations using the parameters of a thin film organic cell which demonstrate that light coupling becomes more effective as the angle for the incident light relative to the fiber array normal increases up to an optimal angle close to 55 deg. At this angle the power conversion efficiency of the fiber array solar cell we propose becomes 30% times larger than the one from an equivalent planar cell configuration. We demonstrate that the micro fiber array solar cell we propose may perform an effective partial tracking of the sun movement for over 100 degrees without any mechanical help. In addition, in the event that such fiber array cell would be installed with the adequate orientation on a vertical façade, an optimal photon-to-charge conversion would be reached for sunlight incident at 55 deg with respect to the horizon line, very close to the yearly average position for the sun at Latitude of 40 deg.

  9. Effect of tellurium deposition rate on the properties of Cu-In-Te based thin films and solar cells

    NASA Astrophysics Data System (ADS)

    Mise, Takahiro; Nakada, Tokio

    2011-01-01

    To investigate the effects of tellurium (Te) deposition rate on the properties of Cu-In-Te based thin films (Cu/In=0.30-0.31), the films were grown on both bare and Mo-coated soda-lime glass substrates at 200 °C by co-evaporation using a molecular beam epitaxy system. The microstructural properties were examined by means of scanning electron microscopy and X-ray diffraction. The crystalline quality of the films was improved with increase in the deposition rate of Te, and exhibited a single CuIn 3Te 5 phase with a highly preferred (1 1 2) orientation. Te-deficient film (Te/(Cu+In)=1.07) grown with a low Te deposition rate showed a narrow bandgap of 0.99 eV at room temperature. The solar cell performance was affected by the deposition rate of Te. The best solar cell fabricated using CuIn 3Te 5 thin films grown with the highest deposition rate of Te (2.6 nm/s) yielded a total area (0.50 cm 2) efficiency of 4.4% ( Voc=309 mV, Jsc=28.0 mA/cm 2, and FF=0.509) without light soaking.

  10. Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells

    SciTech Connect

    Siol, Sebastian; Dhakal, Tara P.; Gudavalli, Ganesh S.; Rajbhandari, Pravakar P.; DeHart, Clay; Baranowski, Lauryn L.; Zakutayev, Andriy

    2016-06-08

    High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in ..beta..-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization techniques. It is demonstrated that, by tuning the sulfur partial pressure, phase pure ..beta..-In2S3 could be deposited using a broad range of substrate temperatures between 500 degrees C and ambient temperature. Combinatorial photovoltaic device libraries with Al/ZnO/In2S3/Cu2ZnSnS4/Mo/SiO2 structure were built at optimal processing conditions to investigate the feasibility of the sputtered In2S3 buffer layers and of an accelerated optimization of the device structure. The performance of the resulting In2S3/Cu2ZnSnS4 photovoltaic devices is on par with CdS/Cu2ZnSnS4 reference solar cells with similar values for short circuit currents and open circuit voltages, despite the overall quite low efficiency of the devices (-2%). Overall, these results demonstrate how a high-throughput experimental approach can be used to accelerate the development of contact materials and facilitate the optimization of thin film solar cell devices.

  11. Combinatorial Reactive Sputtering of In2S3 as an Alternative Contact Layer for Thin Film Solar Cells.

    PubMed

    Siol, Sebastian; Dhakal, Tara P; Gudavalli, Ganesh S; Rajbhandari, Pravakar P; DeHart, Clay; Baranowski, Lauryn L; Zakutayev, Andriy

    2016-06-08

    High-throughput computational and experimental techniques have been used in the past to accelerate the discovery of new promising solar cell materials. An important part of the development of novel thin film solar cell technologies, that is still considered a bottleneck for both theory and experiment, is the search for alternative interfacial contact (buffer) layers. The research and development of contact materials is difficult due to the inherent complexity that arises from its interactions at the interface with the absorber. A promising alternative to the commonly used CdS buffer layer in thin film solar cells that contain absorbers with lower electron affinity can be found in β-In2S3. However, the synthesis conditions for the sputter deposition of this material are not well-established. Here, In2S3 is investigated as a solar cell contact material utilizing a high-throughput combinatorial screening of the temperature-flux parameter space, followed by a number of spatially resolved characterization techniques. It is demonstrated that, by tuning the sulfur partial pressure, phase pure β-In2S3 could be deposited using a broad range of substrate temperatures between 500 °C and ambient temperature. Combinatorial photovoltaic device libraries with Al/ZnO/In2S3/Cu2ZnSnS4/Mo/SiO2 structure were built at optimal processing conditions to investigate the feasibility of the sputtered In2S3 buffer layers and of an accelerated optimization of the device structure. The performance of the resulting In2S3/Cu2ZnSnS4 photovoltaic devices is on par with CdS/Cu2ZnSnS4 reference solar cells with similar values for short circuit currents and open circuit voltages, despite the overall quite low efficiency of the devices (∼2%). Overall, these results demonstrate how a high-throughput experimental approach can be used to accelerate the development of contact materials and facilitate the optimization of thin film solar cell devices.

  12. On-Orbit Demonstration Of Thin-Film Multi-Junction Solar Cells And Lithium-Ion Capacitors As Bus Components

    NASA Astrophysics Data System (ADS)

    Kukita, Akio; Takahashi, Masato; Shimazaki, Kazunori; Toyota, Hiroyuki; Imaizumi, Mitsuru; Kobayashi, Yuki; Takamoto, Tatsuya; Uno, Masatoshi; Shimada, Takanobu

    2011-10-01

    This paper describes an on-orbit demonstration plan for a lightweight solar panel using thin-film multi-junction (MJ) solar cells and aluminum-laminated lithium-ion capacitors (LICs). Thin-film MJ solar cells such as inverted metamorphic InGaP/GaAs/InGaAs 3J cells have flexibility as well as conversion efficiencies superior to conventional rigid 3J solar cells. A substantial reduction of satellite mass is achieved by the combination of thin-film MJ solar cells and light flexible paddles. An LIC is a hybrid-type capacitor that uses activated carbon as the cathode and carbon material pre-doped with lithium ion as the anode. LICs can be rapidly charged and discharged, and can operate in a wide temperature range for long periods. LICs are therefore suitable for long-term missions such as planetary explorations. Although these devices are very promising, so far there has been no opportunity to demonstrate their use in orbit. A lightweight thin solar panel with thin-film MJ solar cells will be installed on the Small Scientific Satellite Platform for Rapid Investigation and Test-A (SPRINT-A) satellite, which will be launched on the Epsilon launch vehicle in 2013. Utilizing the capacitor-like voltage behavior of LICs, we will employ a simple constant-power charging circuit without feedback control.

  13. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    SciTech Connect

    Höger, Ingmar Gawlik, Annett; Brückner, Uwe; Andrä, Gudrun; Himmerlich, Marcel; Krischok, Stefan

    2016-01-28

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiO{sub x}N{sub y}) or silicon oxide (SiO{sub 2}) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiO{sub x}N{sub y} formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiO{sub x}N{sub y} top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  14. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    NASA Astrophysics Data System (ADS)

    Höger, Ingmar; Himmerlich, Marcel; Gawlik, Annett; Brückner, Uwe; Krischok, Stefan; Andrä, Gudrun

    2016-01-01

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiOxNy) or silicon oxide (SiO2) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiOxNy formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiOxNy top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  15. Evaluation of back contact in spray deposited SnS thin film solar cells by impedance analysis.

    PubMed

    Patel, Malkeshkumar; Ray, Abhijit

    2014-07-09

    The role of back metal (M) contact in sprayed SnS thin film solar cells with a configuration Glass/F:SnO2/In2S3/SnS/M (M = Graphite, Cu, Mo, and Ni) was analyzed and discussed in the present study. Impedance spectroscopy was employed by incorporating constant phase elements (CPE) in the equivalent circuit to investigate the degree of inhomogeneity associated with the heterojunction and M/SnS interfaces. A best fit to Nyquist plot revealed a CPE exponent close to unity for thermally evaporated Cu, making it an ideal back contact. The Bode phase plot also exhibited a higher degree of disorders associated with other M/SnS interfaces. The evaluation scheme is useful for other emerging solar cells developed from low cost processing schemes like spray deposition, spin coating, slurry casting, electrodeposition, etc.

  16. Non-destructive Evaluation of Compound Semiconductor Thin-Film Solar Cells by Photothermal Beam Deflection Technique

    NASA Astrophysics Data System (ADS)

    Warrier, Anita R.; Sebastian, Tina; Kartha, C. Sudha; Vijayakumar, K. P.

    2015-01-01

    In this paper, it is demonstrated that the photothermal beam deflection technique can be used for measuring the series resistance, optimum load resistance, and conversion efficiency of thin-film solar cells. This technique is also used for determining the carrier transport properties of an absorber and window layer of -based solar cells during different stages of cell fabrication. Transport properties such as the carrier mobility, lifetime, and surface recombination velocity of the individual absorber and window layer are shown to influence the open-circuit voltage and short-circuit current of the final photovoltaic device. The cell parameters measured using the photothermal technique agree well with the electrical measurements. The principle of the technique is explained on the basis of the "mirage effect" and maximum power transfer theorem.

  17. Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS₂ thin film.

    PubMed

    Tsuboi, Yuka; Wang, Feijiu; Kozawa, Daichi; Funahashi, Kazuma; Mouri, Shinichiro; Miyauchi, Yuhei; Takenobu, Taishi; Matsuda, Kazunari

    2015-09-14

    Transition-metal dichalcogenides exhibit great potential as active materials in optoelectronic devices because of their characteristic band structure. Here, we demonstrated that the photovoltaic performances of graphene/Si Schottky junction solar cells were significantly improved by inserting a chemical vapor deposition (CVD)-grown, large MoS2 thin-film layer. This layer functions as an effective electron-blocking/hole-transporting layer. We also demonstrated that the photovoltaic properties are enhanced with the increasing number of graphene layers and the decreasing thickness of the MoS2 layer. A high photovoltaic conversion efficiency of 11.1% was achieved with the optimized trilayer-graphene/MoS2/n-Si solar cell.

  18. New Layered Structures of Cuprous Chalcogenides as Thin Film Solar Cell Materials: Cu2Te and Cu2Se

    NASA Astrophysics Data System (ADS)

    Nguyen, Manh Cuong; Choi, Jin-Ho; Zhao, Xin; Wang, Cai-Zhuang; Zhang, Zhenyu; Ho, Kai-Ming

    2013-10-01

    The stable crystal structures of two cuprous chalcogenides of Cu2X (X=Te or Se) are predicted using an adaptive genetic algorithm in combination with first-principles density functional theory calculations. Both systems are found to prefer a unique and previously unrecognized layered structure, with the total energies much lower than all structures proposed in the literature so far. The newly discovered structures are further shown to be dynamically and mechanically stable, and possess electronic properties consistent with existing experimental observations. In particular, their layered nature is expected to prevail over other structural forms at the interfaces of thin-film solar cells, and knowledge about the precise atomic structures of the interfaces is a prerequisite for achieving long-term stability and high efficiency of CdTe and Cu(In,Ga)Se2 solar cells.

  19. New layered structures of cuprous chalcogenides as thin film solar cell materials: Cu2Te and Cu2Se.

    PubMed

    Nguyen, Manh Cuong; Choi, Jin-Ho; Zhao, Xin; Wang, Cai-Zhuang; Zhang, Zhenyu; Ho, Kai-Ming

    2013-10-18

    The stable crystal structures of two cuprous chalcogenides of Cu2X (X=Te or Se) are predicted using an adaptive genetic algorithm in combination with first-principles density functional theory calculations. Both systems are found to prefer a unique and previously unrecognized layered structure, with the total energies much lower than all structures proposed in the literature so far. The newly discovered structures are further shown to be dynamically and mechanically stable, and possess electronic properties consistent with existing experimental observations. In particular, their layered nature is expected to prevail over other structural forms at the interfaces of thin-film solar cells, and knowledge about the precise atomic structures of the interfaces is a prerequisite for achieving long-term stability and high efficiency of CdTe and Cu(In,Ga)Se2 solar cells.

  20. Accelerated performance degradation of CIGS solar cell determined by in-situ monitoring

    NASA Astrophysics Data System (ADS)

    Theelen, Mirjam; Barreau, Nicolas; Daume, Felix; Steijvers, Henk; Hans, Vincent; Liakopoulou, Aikaterini; Vroon, Zeger; Zeman, Miro

    2014-10-01

    An `hybrid' degradation setup, in which humidity, temperature and illumination are used in order to accelerate degradation of CIGS, has been developed. This setup consists of a climate chamber, which can vary the temperature and humidity. Furthermore, an area of 80x80 cm2 is illuminated, which allows both the study of light induced behvaior and the in-situ measurement of the IV curve of the cell during the test, so the degradation behavior can be observed in time. The IV output is automatically logged and characteristic parameters like efficiency, currents, voltages, ideality factor and resistance can be extracted. The 40x40 cm2 in the center of the illuminated area was calibrated BAA according to IEC norm 60904-9. Twelve cells or minimodules can be degraded and measured in-situ at the same time. The continuous in-situ IV measurements allowed us to do various studies, including the determination of the temperature dependency and of the impact of light and dark exposure on the performance of CIGS solar cells. Furthermore, the impact of different Na and K concentrations in the CIGS absorber layer on the ininial as well as long term performance of CIGS solar cells was studied.

  1. Theoretical Evaluation of Cu-Sn-S and Cu-Sb-S Based Solar Absorbers for Earth-Abundant Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Zawadzki, Pawel; Peng, Haowei; Zakutayev, Andriy; Lany, Stephan

    2013-03-01

    Current thin-film solar absorbers such as Cu(In/Ga)Se2 or CdTe, although remarkably efficient, incorporate limited-supply elements like indium or tellurium. Meeting the cost competiveness criterion necessary for a large-scale deployment of thin-film PV technologies requires development of new earth-abundant solar absorbers. In an effort to accelerate such development we combine first principles theory and high throughput experiments to explore In-free ternary copper chalcogenides. As part of the theoretical evaluation, we study the Cu2SnS3, Cu4SnS4, CuSbS2 and Cu3SbS3 based compounds formed by isovalent alloying on Sn, Sb, and S sites. For this set of materials we predict band-structures and optical absorption coefficients and demonstrate the feasibility of achieving the optimal band gap of 1.3 eV for a single junction cell and a high optical absorption of ~104 cm-1 at Eg+0.2 eV. We additionally perform defect studies to elucidate the doping trends within this class of materials. The project ``Rapid Development of Earth-abundant Thin Film Solar Cells'' is supported as a part of the SunShot initiative by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy under Contract No. DE-AC36-08GO28308 to NREL.

  2. Optimization of processing and modeling issues for thin film solar cell devices: Final report, February 3, 1997--September 1, 1998

    SciTech Connect

    Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S.; McCandless, B. E.

    2000-02-28

    This final report describes results achieved under a 20-month NREL subcontract to develop and understand thin-film solar cell technology associated to CuInSe{sub 2} and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE's long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development and improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to device structure and module encapsulation.

  3. Effect of fluorine plasma treatment with chemically reduced graphene oxide thin films as hole transport layer in organic solar cells

    NASA Astrophysics Data System (ADS)

    Yu, Youn-Yeol; Kang, Byung Hyun; Lee, Yang Doo; Lee, Sang Bin; Ju, Byeong-Kwon

    2013-12-01

    The inorganic materials such as V2O5, MoO3 and WO3 were investigated to replace PEDOT:PSS as hole transport layer (HTL) in organic electronic devices such as organic solar cells (OSCs) and organic lighting emission diodes. However, these methods require vacuum techniques that are long time process and complex. Here, we report about plasma treatment with SF6 and CF4 using reactive ion etching on reduced graphene oxide (rGO) thin films that are obtained using an eco-friendly method with vitamin C. The plasma treated rGO thin films have dipoles since they consist of covalent bonds with fluorine on the surface of rGO. This means it is possible to increase the electrostatic potential energy than bare rGO. Increased potential energy on the surface of rGO films is worth applying organic electronic devices as HTL such as OSCs. Consequently, the power conversion efficiency of OSCs increased more than the rGO films without plasma treatment.

  4. Easily accessible polymer additives for tuning the crystal-growth of perovskite thin-films for highly efficient solar cells.

    PubMed

    Dong, Qingqing; Wang, Zhaowei; Zhang, Kaicheng; Yu, Hao; Huang, Peng; Liu, Xiaodong; Zhou, Yi; Chen, Ning; Song, Bo

    2016-03-14

    For perovskite solar cells (Pero-SCs), one of the key issues with respect to the power conversion efficiency (PCE) is the morphology control of the perovskite thin-films. In this study, an easily-accessible additive polyethylenimine (PEI) is utilized to tune the morphology of CH3NH3PbI3-xClx. With addition of 1.00 wt% of PEI, the smoothness and crystallinity of the perovskite were greatly improved, which were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A summit PCE of 14.07% was achieved for the p-i-n type Pero-SC, indicating a 26% increase compared to those of the devices without the additive. Both photoluminescence (PL) and alternating current impedance spectroscopy (ACIS) analyses confirm the efficiency results after the addition of PEI. This study provides a low-cost polymer additive candidate for tuning the morphology of perovskite thin-films, and might be a new clue for the mass production of Pero-SCs.

  5. K-edge EXAFS and XANES studies of Cu in CdTe thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Xiangxin; Gupta, Akhlesh; Compaan, Alvin D.; Leyarovska, Nadia; Terry, Jeff

    2002-03-01

    Copper has been identified as a very important dopant element in CdTe thin-film solar cells. Cu is a deep acceptor in CdTe and is commonly used to obtain a heavily doped, low resistance back contact to polycrystalline CdTe. Cu also helps to increase the open circuit voltage of the cell. However, Cu is also a fast diffuser in CdTe, especially along grain boundaries, and can accumulate at the CdS/CdTe junction. It is suspected of leading to cell performance degradation in some cases. The present study is designed to help identify the lattice location of the Cu in CdTe. Cu K-edge, x-ray absorption (XAS) measurements were conducted on Cu in thin films of CdTe. Experiments were performed at the MR-CAT beamline at the Advanced Photon Source. The 3 mm CdTe layers were magnetron sputtered onto fused silica substrates. Some films were diffused with Cu from a 200 Å layer of evaporated Cu. XAS spectra were collected in fluorescence geometry with a 13 elements Ge detector. Quantitative fluorescence spectroscopy measurements were also performed. Details of the Cu environment and possible changes with time will be reported.

  6. Solar-light photoamperometric and photocatalytic properties of quasi-transparent TiO2 nanoporous thin films.

    PubMed

    Ji, Yajun; Lin, Keng-Chu; Zheng, Hegen; Liu, Chung-Chiun; Dudik, Laurie; Zhu, Junjie; Burda, Clemens

    2010-11-01

    Transparent photocatalytic surfaces are of ever increasing importance for many applications on self-cleaning windows and tiles in everyday applications. Here, we report the formation and photocatalytic testing of a quasi-transparent thin and nanoporous titania films deposited on glass plates. Sputtered Ti thin films were anodized in fluoride-ion-containing neutral electrolytes to form optically semitransparent nanoporous films, which transformed to be completely transparent after thermal annealing. The nanoporous films were studied at different stages, such as before and after anodization, as well as after thermal annealing using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis and Raman spectroscopy. It was observed that anodization at 20 V of high-temperature deposited titanium films resulted in regular nanopore films with pore diameters of 30 nm. Structural investigations on the transparent nanopore arrays reveal the presence of anatase phase TiO(2) even after annealing at 500 °C, which was confirmed by XRD and Raman spectroscopy measurements. The solar-light induced photocatalytic decomposition of stearic acid and photoconductivity characteristics of these nanoporous thin films are also presented.

  7. Enhanced electrical properties at boundaries including twin boundaries of polycrystalline CdTe thin-film solar cells.

    PubMed

    Li, H; Liu, X X; Lin, Y S; Yang, B; Du, Z M

    2015-05-07

    The effect of grain boundaries (GBs), in particular twin boundaries (TBs), on CdTe polycrystalline thin films is studied by conductive atomic force microscopy (C-AFM), electron-beam-induced current (EBIC), scanning Kelvin probe microscopy (SKPM), electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM). Four types of CdTe grains with various densities of {111} Σ3 twin boundaries (TBs) are found in Cl-treated CdTe polycrystalline thin films: (1) grains having multiple {111} Σ3 TBs with a low angle to the film surface; (2) grains having multiple {111} Σ3 TBs parallel to the film surfaces; (3) small grains on a scale of not more than 500 nm, composed of Cd, Cl, Te, and O; and (4) CdTe grains with not more than two {111} Σ3 TBs. Grain boundaries (including TBs) exhibit enhanced current transport phenomena. However, the {111} Σ3 TB is much more beneficial to micro-current transport. The enhanced current transport can be explained by the lower electron potential at GBs (including TBs) than the grain interiors (GIs). Our results open new opportunities for enhancing solar cell performances by controlling the grain boundaries, and in particular TBs.

  8. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  9. Understanding and Enhancing the Photostability of Nanoporous Metal Oxide Thin Films for Solar Hydrogen Generation

    NASA Astrophysics Data System (ADS)

    Chitrada, Kalyan Chakravarthi

    under dark conditions. The binary bismuth (III) oxide, in spite being a good photocatalytic material, did not receive as much attention as other bismuth based ternary oxides for photoelectrochemical water splitting application. In this present study, large surface area nanoporous bismuth oxide thin films were synthesized by the electrochemical anodization. These anodic oxides exhibited a dual layered structure having a planar inner oxide and nanoporous outer oxide. Effect of the nanoscale dimensions of the oxides on the photoelectrochemical behavior was studied to understand the charge transport, charge recombination behavior, and long term stability of the material. A maximum photo current density of 0.97 mA/cm2 was observed for the sample anodized at 10 V at 1.53 VRHE. The nanoporous anodic oxides showed a charge carrier density in the range of 1.2 x 1017 -- 4.8 x 1018 cm-3 without illumination and about 60% increase in the charge carrier density upon illumination. However a decay in photo current was observed for the bismuth oxide samples was due to accumulation of holes on the electrode surface. This hole-accumulation was mitigated by the addition of hole scavengers. Addition of hydrogen peroxide as hole scavenger increased the photo current density by about 4 times in 0.5 M Na2SO 4 (pH: 5.8) electrolyte. Addition of H2O2 in 1 M KOH (pH: 13.7) showed an increase-decrease behavior and high photo current density of ~10 mA/cm2 at a bias potential of 0.65 VRHE . The high photo activity observed in this electrolyte was attributed to the in-situ formation of Bi2O4-x phase by the photo-conversion of the beta-Bi2O3 at the surface. The photo-converted Bi2O4-x has a smaller band gap (1.4 eV) and therefore harvested more light in the visible region. This in-situ formation of low band gap phases in the presence of H2O2 during solar water splitting is an interesting observation which has been reported for the first time and this will help design material with very high photo-activity.

  10. Ultra-Lightweight Hybrid Thin-Film Solar Cells: A Survey of Enabling Technologies for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; McNatt, Jeremiah S.; Bailey, Sheila G.; Dickman, John E.; Raffaelle, Ryne P.; Landi, Brian J.; Anctil, Annick; DiLeo, Roberta; Jin, Michael H.-C.; Lee, Chung-Young; Friske, Theresa J.; Sun, Sam-S.; Zhang, Cheng; Choi, S.; Ledbetter, Abram; Seo, Kang; Bonner, Carl E.; Banger, Kulbinder K.; Castro, Stephanie L.; Rauh, David

    2007-01-01

    The development of hybrid inorganic/organic thin-film solar cells on flexible, lightweight, space-qualified, durable substrates provides an attractive solution for fabricating solar arrays with high mass specific power (W/kg). Next generation thin-film technologies may well involve a revolutionary change in materials to organic-based devices. The high-volume, low-cost fabrication potential of organic cells will allow for square miles of solar cell production at one-tenth the cost of conventional inorganic materials. Plastic solar cells take a minimum of storage space and can be inflated or unrolled for deployment. We will explore a cross-section of in-house and sponsored research efforts that aim to provide new hybrid technologies that include both inorganic and polymer materials as active and substrate materials. Research at University of Texas at Arlington focuses on the fabrication and use of poly(isothianaphthene-3,6-diyl) in solar cells. We describe efforts at Norfolk State University to design, synthesize and characterize block copolymers. A collaborative team between EIC Laboratories, Inc. and the University of Florida is investigating multijunction polymer solar cells to more effectively utilize solar radiation. The National Aeronautics and Space Administration (NASA)/Ohio Aerospace Institute (OAI) group has undertaken a thermal analysis of potential metallized substrates as well as production of nanoparticles of CuInS2 and CuInSe2 in good yield at moderate temperatures via decomposition of single-source precursors. Finally, preliminary work at the Rochester Institute of Technology (R.I.T.) to assess the impact on performance of solar cells of temperature and carbon nanotubes is reported. Technologies that must be developed to enable ultra-lightweight solar arrays include: monolithic interconnects, lightweight array structures, and new ultra-light support and deployment mechanisms. For NASA applications, any solar cell or array technology must not only meet

  11. Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration

    NASA Astrophysics Data System (ADS)

    Dahal, Lila Raj

    Real time spectroscopic ellipsometry (RTSE), and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization techniques capable of performance optimization and scale-up evaluation of thin film solar cells used in various photovoltaics technologies. These non-invasive optical probes employ multichannel spectral detection for high speed and provide high precision parameters that describe (i) thin film structure, such as layer thicknesses, and (ii) thin film optical properties, such as oscillator variables in analytical expressions for the complex dielectric function. These parameters are critical for evaluating the electronic performance of materials in thin film solar cells and also can be used as inputs for simulating their multilayer optical performance. In this Thesis, the component layers of thin film hydrogenated silicon (Si:H) solar cells in the n-i-p or substrate configuration on rigid and flexible substrate materials have been studied by RTSE and ex-situ mapping SE. Depositions were performed by magnetron sputtering for the metal and transparent conducting oxide contacts and by plasma enhanced chemical vapor deposition (PECVD) for the semiconductor doped contacts and intrinsic absorber layers. The motivations are first to optimize the thin film Si:H solar cell in n-i-p substrate configuration for single-junction small-area dot cells and ultimately to scale-up the optimized process to larger areas with minimum loss in device performance. Deposition phase diagrams for both i- and p -layers on 2" x 2" rigid borosilicate glass substrate were developed as functions of the hydrogen-to-silane flow ratio in PECVD. These phase diagrams were correlated with the performance parameters of the corresponding solar cells, fabricated in the Cr/Ag/ZnO/n/i/ p/ITO structure. In both cases, optimization was achieved when the layers were deposited in the protocrystalline phase. Identical solar cell structures were fabricated on 6" x 6" borosilicate glass with

  12. Preparation and characterization of hydrogenated amorphous silicon thin films and thin film solar cells produced by ion plating techniques. Final report, 1 January 1979-31 May 1980

    SciTech Connect

    1980-05-01

    Ion plating techniques for the preparation of hydrogenated amorphous silicon thin films have been successfully developed. The technique involves essentially the evaporation of elemental silicon through a d.c. produced hydrogen plasma. In this way hydrogen has been successfully incorporated into amorphous silicon films in concentrations as high as 30 atomic percent. Infrared spectroscopy indicates the usual SiH/sub x/ stretching mode at approximately 2000 cm/sup -1/. Further evidence for the bonding of hydrogen was obtained from ESR measurement of hydrogenated and unhydrogenated samples. The measured unpaired spin density was a factor of 25 less in the hydrogenated sample. The optical absorption edges of the hydrogenated films fell in the usual range between 1.7 and 1.9 eV. Electrical conductivity measurements indicated a substantial reduction in the density of defect states in the gap as expected. It was also shown that hydrogenated amorphous silicon prepared by ion-plating could be doped by co-evaporation of the dopant element during film deposition. Both co-evaporated phosphorous and co-evaporated bismuth have been found to substantially increase the dark conductivity of a-Si:H while shifting the Fermi level towards the conduction band edge. An x-ray method for estimating the density and hydrogen content of a-Si:H has been developed. The measurement of strain in a-Si:H thin films is discussed. (WHK)

  13. Multi-junction Thin-film Solar Cells on Flexible Substrates for Space Power

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Smith, Mark; Scofield, John H.; Dickman, John E.; Lush, Gregory B.; Morel, Donald L.; Ferekides, Christos; Dhere, Neelkanth G.

    2002-01-01

    The ultimate objective of the thin-film program at NASA GRC is development of a 20 percent AM0 thin-film device technology with high power/weight ratio. Several approaches are outlined to improve overall device efficiency and power/weight ratio. One approach involves the use of very lightweight flexible substrates such as polyimides (i.e., Kapton(Trademark)) or metal foil. Also, a compound semiconductor tandem device structure that can meet this objective is proposed and simulated using Analysis of Microelectronic and Photonic Structures (AMPS). AMPS modeling of current devices in tandem format indicate that AM0 efficiencies near 20 percent can be achieved. And with improvements in materials, efficiencies approaching 25 percent are achievable. Several important technical issues need to be resolved to realize these complex devices: development of a wide bandgap material with good electronic properties, development of transparent contacts, and targeting a 2-terminal device structure (with more complicated processing and tunnel junction) or 4-terminal device. Recent progress in the NASA GRC program is outlined.

  14. Nanostructured Thin Film Solar Cells: A Heterojunction of PbS Colloidal Quantum Dots and TiO2 Nanopillars

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Cheol; Kramer, Illan; Bass, John; Topuria, Teya; Krupp, Leslie; Rice, Philip; Debnath, Ratan; Brzozowski, Lukasz; Levina, Larissa; Sargent, Edward

    2011-03-01

    Colloidal quantum dot (CQD) has been recognized as a promising solar cell material that offers tunable band gap and inexpensive solution process. Recent report demonstrated the power conversion efficiency (PCE) of above 5% (AM 1.5) using thin films of PbS CQDs and Ti O2 nanoparticles. This so-called depleted-heterojunction-CQD solar cells have overcome limitations of CQD Schottky devices and promised potential for further improvement of solar cell performance. In this paper, we report the effect of nanostructures of Ti O2 on the performance of heterojunction CQD solar cells. Well-defined nanopillars of Ti O2 were prepared on top of F: Sn O2 substrate using micro-transfer molding technique. Ti O2 nanopillars of 70 nm in diameter (half-width), 340 nm in height and 275 nm in center-to-center distance were used for subsequent layer-by-layer spin coating of PbS CQD. PCE of 5% was measured for the nanopillar solar cells without extensive optimization. Detailed studies on the microstructure of materials, surface properties, optical and electrical properties and optimization will be discussed along with performance of flat TiO2 -PbS CQD solar cells.

  15. CuInSe₂ thin-film solar cells with 7.72 % efficiency prepared via direct coating of a metal salts/alcohol-based precursor solution.

    PubMed

    Ahn, Sejin; Son, Tae Hwa; Cho, Ara; Gwak, Jihye; Yun, Jae Ho; Shin, Keeshik; Ahn, Seoung Kyu; Park, Sang Hyun; Yoon, Kyunghoon

    2012-09-01

    A simple direct solution coating process for forming CuInSe₂ (CIS) thin films was described, employing a low-cost and environmentally friendly precursor solution. The precursor solution was prepared by mixing metal acetates, ethanol, and ethanolamine. The facile formation of a precursor solution without the need to prefabricate nanoparticles enables a rapid and easy processing, and the high stability of the solution in air further ensures the precursor preparation and the film deposition in ambient conditions without a glove box. The thin film solar cell fabricated with the absorber film prepared by this route showed an initial conversion efficiency of as high as 7.72 %.

  16. Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

    SciTech Connect

    Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z.

    2015-04-24

    One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

  17. Research on structural characteristics of large-scale CdS thin films deposited by CBD under low ammonia condition

    NASA Astrophysics Data System (ADS)

    Xue, Yu-ming; Gao, Lin; Yin, Fu-hong; Qiao, Zai-xiang; Liu, Hao; Feng, Shao-jun; Sun, Hai-tao; Hang, Wei

    2015-07-01

    Cadmium sulfide (CdS) buffer layers with the scale of 10 cm×10 cm are deposited by chemical bath deposition (CBD) with different temperatures and thiourea concentrations under low ammonia condition. There are obvious hexagonal phases and cubic phases in CdS thin films under the conditions of low temperature and high thiourea concentration. The main reason is that the heterogeneous reaction is dominant for homogeneous reaction. At low temperature, CdS thin films with good uniformity and high transmittance are deposited by adjusting the thiourea concentration, and there is almost no precipitation in reaction solution. In addition, the low temperature is desired in assembly line. The transmittance and the band gap of CdS thin films are above 80% and about 2.4 eV, respectively. These films are suitable for the buffer layers of large-scale Cu(In,Ga)Se2 (CIGS) solar cells.

  18. Understanding the light soaking effect of ZnMgO buffer in CIGS solar cells.

    PubMed

    Kim, Suncheul; Lee, Chang-Soo; Kim, Seungtae; Chalapathy, R B V; Al-Ammar, Essam A; Ahn, Byung Tae

    2015-07-15

    This study investigated the mechanism underlying the light soaking effect of a ZnMgO buffer in Cu(In,Ga)Se2 (CIGS) solar cells, where the cell efficiency increased with an increase of light soaking time. The ZnMgO buffer layer was deposited by an atomic layer deposition method. With light soaking, the cell efficiency of ZnMgO/CIGS cells increased mainly by the increase of the fill factor and partly by the increase of the open-circuit voltage. With light soaking, the electron carrier concentration of the ZnMgO layer increased and the XPS intensity of the hydroxyl bond in the ZnMgO layer decreased. Based on the above results and the comparison of other buffers in literature, we assumed that the hydrogen atoms broken away from the hydroxyl bond by photon irradiation occupied the interstitial sites of the ZnMgO layer as a donor atom and also passivated the defects at the ZnMgO/CIGS interface. The increase of the fill factor and open circuit voltage was explained based on H doping in the ZnMgO layer and H passivation at the ZnO/CIGS interface.

  19. 21-kW Thin-Film PV Technology Validation -- An NREL/Solar Energy Centre of India MOU Cooperative Project

    SciTech Connect

    McNutt, P. F.; Ullal, H. S.

    2005-01-01

    This paper summarizes findings during a one-week (27-31 October 2003) site visit to the Thin-Film Technology Test Bed at India's Solar Energy Centre (SEC) near New Delhi. The U.S. and Indian governments signed a Memorandum of Understanding in March 2000 to undertake a 50-50 cost-shared 21-kW thin-film PV technology validation project to evaluate the performance of thin-film photovoltaic (PV) modules under Indian climatic conditions. This project benefits Indian researchers by giving them experience with cost-effective PV materials, and it benefits the United States because data will be sent to the appropriate U.S. thin-film PV manufacturers for evaluation and analysis. During the visit, NREL personnel engaged in technical discussions regarding thin-film PV technologies with Ministry of Non-Conventional Energy Sources engineers and scientists. Issues included inspecting the newly constructed arrays, discussing better methods of electrically loading the PV arrays, taking I-V traces, and gathering baseline I-V data.

  20. Investigation of blister formation in sputtered Cu{sub 2}ZnSnS{sub 4} absorbers for thin film solar cells

    SciTech Connect

    Bras, Patrice; Sterner, Jan; Platzer-Björkman, Charlotte

    2015-11-15

    Blister formation in Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films sputtered from a quaternary compound target is investigated. While the thin film structure, composition, and substrate material are not correlated to the blister formation, a strong link between sputtering gas entrapment, in this case argon, and blistering effect is found. It is shown that argon is trapped in the film during sputtering and migrates to locally form blisters during the high temperature annealing. Blister formation in CZTS absorbers is detrimental for thin film solar cell fabrication causing partial peeling of the absorber layer and potential shunt paths in the complete device. Reduced sputtering gas entrapment, and blister formation, is seen for higher sputtering pressure, higher substrate temperature, and change of sputtering gas to larger atoms. This is all in accordance with previous publications on blister formation caused by sputtering gas entrapment in other materials.

  1. Intercalation Crystallization of Phase-Pure ..alpha..-HC(NH2)2PbI3 upon Microstructurally Engineered PbI2 Thin Films for Planar Perovskite Solar Cells

    SciTech Connect

    Zhou, Yuanyuan; Yang, Mengjin; Kwun, Joonsuh; Game, Onkar S.; Zhao, Yixin; Pang, Shuping; Padture, Nitin P.; Zhu, Kai

    2016-03-28

    The microstructure of the solid-PbI2 precursor thin film plays an important role in the intercalation crystallization of the formamidinium lead triiodide perovskite (..alpa..-HC(NH2)2PbI3). It is shown that microstructurally engineered PbI2 thin films with porosity and low crystallinity are the most favorable for conversion into uniform-coverage, phase-pure ..alpha..-HC(NH2)2PbI3 perovskite thin films. Planar perovskite solar cells fabricated using these thin films deliver power conversion efficiency (PCE) up to 13.8%.

  2. Conducting glasses recovered from thin film transistor liquid crystal display wastes for dye-sensitized solar cell cathodes.

    PubMed

    Chen, C-C; Chang, F-C; Peng, C Y; Wang, H Paul

    2015-01-01

    Transparent conductive glasses such as thin film transistor (TFT) array and colour filter glasses were recovered from the TFT-liquid crystal display panel wastes by dismantling and sonic cleaning. Noble metals (i.e. platinum (Pt)) and indium tin oxide (ITO) are generally used in the cathode of a dye-sensitized solar cell (DSSC). To reduce the DSSC cost, Pt was replaced with nano nickel-encapsulated carbon-shell (Ni@C) nanoparticles, which were prepared by carbonization of Ni²⁺-β-cyclodextrin at 673 K for 2 h. The recovered conductive glasses were used in the DSSC electrodes in the substitution of relatively expensive ITO. Interestingly, the efficiency of the DSSC having the Ni@C-coated cathode is as high as 2.54%. Moreover, the cost of the DSSC using the recovered materials can be reduced by at least 24%.

  3. Cadmium sulfide nanowires for the window semiconductor layer in thin film CdS-CdTe solar cells.

    PubMed

    Liu, Piao; Singh, Vijay P; Jarro, Carlos A; Rajaputra, Suresh

    2011-04-08

    Thin film CdS/CdTe heterojunction device is a leading technology for the solar cells of the next generation. We report on two novel device configurations for these cells where the traditional CdS window layer is replaced by nanowires (NW) of CdS, embedded in an aluminum oxide matrix or free-standing. An estimated 26.8% improvement in power conversion efficiency over the traditional device structure is expected, primarily because of the enhanced spectral transmission of sunlight through the NW-CdS layer and a reduction in the junction area/optical area ratio. In initial experiments, nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved.

  4. Plasmonic organic thin-film solar cell: light trapping by using conformal vs. non-conformal relief gratings

    NASA Astrophysics Data System (ADS)

    Keshmiri, Hamid; Dostlek, Jakub

    2015-05-01

    Theoretical study of light management in thin film organic photovoltaic cell that utilizes diffraction coupling to guided waves is presented. As a model system, a regular solar cell geometry with P3HT:PCBM active layer, transparent ITO electrode and Al backside electrode is used. The paper discusses enhancement of absorption of incident photons selectively in the active layer by the interplay of surface plasmon polariton and optical waveguide waves, the effect on the profile of their field and damping that affects the spatial distribution of dissipated light energy in the layer structure. The model shows that for optimized grating period and modulation depth the number of absorbed photons in the active layer can be increased by 24 per cent. The comparison of the geometry with conformal and non-conformally corrugated layers reveals that the conformal structure outperforms the non-conformal in the enhancing of photon absorption in the wavelength range of 350-800 nm.

  5. Band alignment in SnS thin-film solar cells: Possible origin of the low conversion efficiency

    NASA Astrophysics Data System (ADS)

    Burton, Lee A.; Walsh, Aron

    2013-04-01

    Tin sulfide is an attractive absorber material for low-cost thin-film solar cells. Despite the ideal physical properties of bulk SnS, the photovoltaic conversion efficiencies achieved in devices to date have been no greater than 2%. Assessment of the valence band energy of the stable orthorhombic phase of SnS reveals a low ionisation potential (4.7 eV) in comparison to typical absorber materials (CdTe, CuInSe2, and Cu2ZnSnS4). A band mis-alignment is therefore predicted with commonly used back contact and buffer layers. Alternative configurations are proposed that should improve device performance.

  6. Surface Modification of Polycrystalline Cu(In,Ga)Se2 Thin-Film Solar Cell Absorber Surfaces for PEEM Measurements

    SciTech Connect

    Wilks, R. G.; Contreras, M. A.; Lehmann, S.; Herrero-Albillos, J.; Bismaths, L. T.; Kronast, F.; Noufi, R.; Bar, M.

    2011-01-01

    We present a thorough examination of the {micro}m-scale topography of Cu(In, Ga)Se{sub 2} ('CIGSe') thin-film solar cell absorbers using different microscopy techniques. We specifically focus on the efficacy of preparing smooth sample surfaces - by etching in aqueous bromine solution - for a spatially resolved study of their chemical and electronic structures using photoelectron emission microscopy (PEEM). The etching procedure is shown to reduce the CIGSe surface roughness from ca. 40 to 25 nm after 40s etching, resulting in an increase in the quality of the obtained PEEM images. Furthermore we find that the average observed grain size at the etched surfaces appears larger than at the unetched surfaces. Using a liftoff procedure, it is additionally shown that the backside of the absorber is flat but finely patterned, likely due to being grown on the finely-structured Mo back contact.

  7. Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions

    SciTech Connect

    Hoque, Md Nadim Ferdous; Yang, Mengjin; Li, Zhen; Islam, Nazifah; Pan, Xuan; Zhu, Kai; Fan, Zhaoyang

    2016-07-08

    Researchers have debated whether methylammonium lead iodide (MAPbI3), with a perovskite crystal structure, is ferroelectric and therefore contributes to the current--voltage hysteresis commonly observed in hybrid perovskite solar cells (PSCs). We thoroughly investigated temperature-dependent polarization, dielectric, and impedance spectroscopies, and we found no evidence of ferroelectric effect in a MAPbI3 thin film at normal operating conditions. Therefore, the effect does not contribute to the hysteresis in PSCs, whereas the large component of ionic migration observed may play a critical role. Our temperature-based polarization and dielectric studies find that MAPbI3 exhibits different electrical behaviors below and above ca. 45 degrees C, suggesting a phase transition around this temperature. In particular, we report the activation energies of ionic migration for the two phases and temperature-dependent permittivity of MAPbI3. This study contributes to the understanding of the material properties and device performance of hybrid perovskites.

  8. Properties Of A Qualified Space Solar Sheet With InGaP/GaAs Dual-Junction Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Imaizumi, Mitsuru; Shimazaki, Kazunori; Kobayashi, Yuki; Takahashi, Masato; Nakamura, Kazuyo; Takamoto, Tatsuya; Sata, Shin-ichiro; Ohshima, Takeshi

    2011-10-01

    JAXA's approach to realizing a high specific power solar paddle by utilizing thin-film III-V multi-junction solar cells is introduced. Thin-film cells laminated with thin and transparent sustaining materials have been named a "Space Solar Sheet (SSS)." Development of the first-generation SSS (SSS-1) was completed in 2010. Thin-film InGaP/GaAs dual-junction (TF2J) cells are used as solar cells in the SSS-1. The AM0 efficiency of the TF2J cells is ~25%. Two types of lamination structure for the active side are employed: one uses transparent films with UV coating, and the other has a conventional configuration using a coverglass. The specific power of the SSS-1 is 0.4-0.5 W/g. Characterization and environmental qualification tests have confirmed their space quality and life at more than 5 years in the LEO environment (the film type) and 10 years in the GEO environment (the coverglass type). The SSS-1 is now commercially available. The second- generation SSS (SSS-2) development started in 2010. The major improvement from the SSS-1 to the SSS-2 will be cell efficiency, achieved by adopting an inverted metamorphic InGaP/GaAs/InGaAs triple-junction solar cell: the target efficiency is 32% at BOL. The lamination technology will be also modified for the SSS-2 to improve specific power. The achievement of such a SSS will enable us to realize lightweight solar paddles with specific power of 150 W/kg or greater.

  9. Effect of the KF post-deposition treatment on grain boundary properties in Cu(In, Ga)Se2 thin films.

    PubMed

    Nicoara, N; Lepetit, Th; Arzel, L; Harel, S; Barreau, N; Sadewasser, S

    2017-01-27

    Significant power conversion efficiency improvements have recently been achieved for thin-film solar cells based on a variety of polycrystalline absorbers, including perovskites, CdTe, and Cu(In,Ga)Se2 (CIGS). The passivation of grain boundaries (GBs) through (post-deposition) treatments is a crucial step for this success. For the case of CIGS, the introduction of a potassium fluoride post-deposition treatment (KF-PDT) has boosted their power conversion efficiency to the best performance of all polycrystalline solar cells. Direct and indirect effects of potassium at the interface and interface-near region in the CIGS layer are thought to be responsible for this improvement. Here, we show that also the electronic properties of the GBs are beneficially modified by the KF-PDT. We used Kelvin probe force microscopy to study the effect of the KF-PDT on the CIGS surface by spatially resolved imaging of the surface potential. We find a clear difference for the GB electronic properties: the KF-PDT increases the band bending at GBs by about 70% and results in a narrower distribution of work function values at the GBs. This effect of the KF-PDT on the GB electronic properties is expected to contribute to the improved efficiency values observed for CIGS thin-film solar cells with KF-PDT.

  10. Effect of the KF post-deposition treatment on grain boundary properties in Cu(In, Ga)Se2 thin films

    PubMed Central

    Nicoara, N.; Lepetit, Th.; Arzel, L.; Harel, S.; Barreau, N.; Sadewasser, S.

    2017-01-01

    Significant power conversion efficiency improvements have recently been achieved for thin-film solar cells based on a variety of polycrystalline absorbers, including perovskites, CdTe, and Cu(In,Ga)Se2 (CIGS). The passivation of grain boundaries (GBs) through (post-deposition) treatments is a crucial step for this success. For the case of CIGS, the introduction of a potassium fluoride post-deposition treatment (KF-PDT) has boosted their power conversion efficiency to the best performance of all polycrystalline solar cells. Direct and indirect effects of potassium at the interface and interface-near region in the CIGS layer are thought to be responsible for this improvement. Here, we show that also the electronic properties of the GBs are beneficially modified by the KF-PDT. We used Kelvin probe force microscopy to study the effect of the KF-PDT on the CIGS surface by spatially resolved imaging of the surface potential. We find a clear difference for the GB electronic properties: the KF-PDT increases the band bending at GBs by about 70% and results in a narrower distribution of work function values at the GBs. This effect of the KF-PDT on the GB electronic properties is expected to contribute to the improved efficiency values observed for CIGS thin-film solar cells with KF-PDT. PMID:28128351

  11. Effect of the KF post-deposition treatment on grain boundary properties in Cu(In, Ga)Se2 thin films

    NASA Astrophysics Data System (ADS)

    Nicoara, N.; Lepetit, Th.; Arzel, L.; Harel, S.; Barreau, N.; Sadewasser, S.

    2017-01-01

    Significant power conversion efficiency improvements have recently been achieved for thin-film solar cells based on a variety of polycrystalline absorbers, including perovskites, CdTe, and Cu(In,Ga)Se2 (CIGS). The passivation of grain boundaries (GBs) through (post-deposition) treatments is a crucial step for this success. For the case of CIGS, the introduction of a potassium fluoride post-deposition treatment (KF-PDT) has boosted their power conversion efficiency to the best performance of all polycrystalline solar cells. Direct and indirect effects of potassium at the interface and interface-near region in the CIGS layer are thought to be responsible for this improvement. Here, we show that also the electronic properties of the GBs are beneficially modified by the KF-PDT. We used Kelvin probe force microscopy to study the effect of the KF-PDT on the CIGS surface by spatially resolved imaging of the surface potential. We find a clear difference for the GB electronic properties: the KF-PDT increases the band bending at GBs by about 70% and results in a narrower distribution of work function values at the GBs. This effect of the KF-PDT on the GB electronic properties is expected to contribute to the improved efficiency values observed for CIGS thin-film solar cells with KF-PDT.

  12. A facile chemical-mechanical polishing lift-off transfer process toward large scale Cu(In,Ga)Se2 thin-film solar cells on arbitrary substrates

    NASA Astrophysics Data System (ADS)

    Tseng, Kuan-Chun; Yen, Yu-Ting; Thomas, Stuart R.; Tsai, Hung-Wei; Hsu, Cheng-Hung; Tsai, Wen-Chi; Shen, Chang-Hong; Shieh, Jia-Min; Wang, Zhiming M.; Chueh, Yu-Lun

    2016-02-01

    The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide variety of flexible substrates, suitable for use in the large scale CIGS photovoltaic industry.The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide

  13. Improving Si solar cell performance using Mn:ZnSe quantum dot-doped PLMA thin film

    NASA Astrophysics Data System (ADS)

    Cheng, Dan-Chen; Hao, Hong-Chen; Zhang, Miao; Shi, Wei; Lu, Ming

    2013-06-01

    Poly(lauryl methacrylate) (PLMA) thin film doped with Mn:ZnSe quantum dots (QDs) was spin-deposited on the front surface of Si solar cell for enhancing the solar cell efficiency via photoluminescence (PL) conversion. Significant solar cell efficiency enhancements (approximately 5% to 10%) under all-solar-spectrum (AM0) condition were observed after QD-doped PLMA coatings. Furthermore, the real contribution of the PL conversion was precisely assessed by investigating the photovoltaic responses of the QD-doped PLMA to monochromatic and AM0 light sources as functions of QD concentration, combined with reflectance and external quantum efficiency measurements. At a QD concentration of 1.6 mg/ml for example, among the efficiency enhancement of 5.96%, about 1.04% was due to the PL conversion, and the rest came from antireflection. Our work indicates that for the practical use of PL conversion in solar cell performance improvement, cautions are to be taken, as the achieved efficiency enhancement might not be wholly due to the PL conversion.

  14. Electrodeposited ZnS Precursor Layer with Improved Electrooptical Properties for Efficient Cu2ZnSnS4 Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Mkawi, E. M.; Ibrahim, K.; Ali, M. K. M.; Farrukh, M. A.; Mohamed, A. S.

    2015-10-01

    Zinc sulfide (ZnS) thin films were prepared on indium tin oxide-coated glass by electrodeposition using aqueous zinc sulfate, thiourea, and ammonia solutions at 80°C. The effects of sulfurization at temperatures of 350°C, 400°C, 450°C, and 500°C on the morphological, structural, optical, and electrical properties of the ZnS thin films were investigated. X-ray diffraction analysis showed that the ZnS thin films exhibited cubic zincblende structure with preferred (111) orientation. The film crystallization improved with increasing annealing temperature. Field-emission scanning electron microscopy images showed that the film morphology became more compact and uniform with increasing annealing temperature. The percentage of sulfur in the ZnS thin films increased after sulfurization until a stoichiometric S/Zn ratio was achieved at 500°C. The annealed films showed good adhesion to the glass substrates, with moderate transmittance (85%) in the visible region. Based on absorption measurements, the direct bandgap increased from 3.71 eV to 3.79 eV with annealing temperature, which is attributed to the change of the buffer material composition and suitable crystal surface properties for effective p- n junction formation. The ZnS thin films were used as a buffer layer in thin-film solar cells with the structure of soda-lime glass/Mo/Cu2ZnSnS4/ZnS/ZnO/Al grid. The best solar cell efficiency was 1.86%.

  15. Structural properties of indium tin oxide thin films prepared for application in solar cells

    SciTech Connect

    Gheidari, A. Mohammadi; Mohajerzadeh, S.; Shams-Kolahi, W.

    2005-08-11

    Indium tin oxide (ITO) thin films prepared by rf sputtering were annealed in several temperatures. The electrical, optical and structural properties of these films are systematically investigated. The post annealing of the samples lead to considerably higher electrical conductivity, better optical transparency and larger grain size for the films. In an optimum annealing temperature of 400 deg. C, we have found that a maximized conductivity of films is achieved without a remarkable loss in their transparency. The sheet resistance of 2.3 {omega}/{open_square} and average grain size of 30 nm, are the results of the optimized post processing of films. The investigation for microstructure of films investigated by X-ray diffraction measurement (XRD) shows that a preferential crystal growth toward the (2 2 2) orientation takes place when the annealing temperature increases to 400 deg. C.

  16. Process for fabricating polycrystalline semiconductor thin-film solar cells, and cells produced thereby

    DOEpatents

    Wu, Xuanzhi; Sheldon, Peter

    2000-01-01

    A novel, simplified method for fabricating a thin-film semiconductor heterojunction photovoltaic device includes initial steps of depositing a layer of cadmium stannate and a layer of zinc stannate on a transparent substrate, both by radio frequency sputtering at ambient temperature, followed by the depositing of dissimilar layers of semiconductors such as cadmium sulfide and cadmium telluride, and heat treatment to convert the cadmium stannate to a substantially single-phase material of a spinel crystal structure. Preferably, the cadmium sulfide layer is also deposited by radio frequency sputtering at ambient temperature, and the cadmium telluride layer is deposited by close space sublimation at an elevated temperature effective to convert the amorphous cadmium stannate to the polycrystalline cadmium stannate with single-phase spinel structure.

  17. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    SciTech Connect

    Burghoorn, M.; Kniknie, B.; Deelen, J. van; Ee, R. van; Xu, M.; Vroon, Z.; Belt, R. van de; Buskens, P. E-mail: buskens@dwi.rwth-aachen.de

    2014-12-15

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (J{sub sc}) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the J{sub sc} and efficiency of CIGS solar cells with an absorber layer thickness (d{sub CIGS}) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (n{sub resist} = 1.792 vs. n{sub AZO} = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, J{sub sc} increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in J{sub sc} with decreasing d{sub CIGS} was observed. Ergo, the increase in J{sub sc} can be fully explained by the reduction in reflection, and we did not observe any increase in J{sub sc} based on an increased photon path length.

  18. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Burghoorn, M.; Kniknie, B.; van Deelen, J.; Xu, M.; Vroon, Z.; van Ee, R.; van de Belt, R.; Buskens, P.

    2014-12-01

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 vs. nAZO = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.

  19. Compositional and Interfacial Modification of Cu2 ZnSn(S,Se)4 Thin-Film Solar Cells Prepared by Electrochemical Deposition.

    PubMed

    Seo, Se Won; Jeon, Jong-Ok; Seo, Jung Woo; Yu, Yi Yin; Jeong, Jeung-Hyun; Lee, Doh-Kwon; Kim, Honggon; Ko, Min Jae; Son, Hae Jung; Jang, Ho Won; Kim, Jin Young

    2016-03-08

    A highly efficient Cu2 ZnSn(S,Se)4 (CZTSSe)-based thin-film solar cell (9.9%) was prepared using an electrochemical deposition method followed by thermal annealing. The Cu-Zn-Sn alloy films was grown on a Mo-coated glass substrate using a one-pot electrochemical deposition process, and the metallic precursor films was annealed under a mixed atmosphere of S and Se to form CZTSSe thin films with bandgap energies ranging from 1.0 to 1.2 eV. The compositional modification of the S/(S+Se) ratio shows a trade-off effect between the photocurrent and photovoltage, resulting in an optimum bandgap of roughly 1.14 eV. In addition, the increased S content near the p-n junction reduces the dark current and interface recombination, resulting in a further enhancement of the open-circuit voltage. As a result of the compositional and interfacial modification, the best CZTSSe-based thin-film solar cell exhibits a conversion efficiency of 9.9%, which is among the highest efficiencies reported so far for electrochemically deposited CZTSSe-based thin-film solar cells.

  20. A general water-based precursor solution approach to deposit earth abundant Cu2ZnSn(S,Se)4 thin film solar cells

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    Earth abundant Cu2ZnSn(S,Se)4 (CZTSSe) has been considered as one of the most promising thin film solar cell absorber candidates. Here, we develop a facile water-based precursor solution approach for depositing high-efficiency Cu2ZnSn(S,Se)4 thin film solar cells. In this environmentally friendly approach, inexpensive elemental Cu, Zn, Sn and S powders are used as the starting materials and are