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Sample records for a-si thin-film solar

  1. Light trapping in a-Si:H thin film solar cells using silver nanostructures

    NASA Astrophysics Data System (ADS)

    Wang, P. H.; Theuring, M.; Vehse, M.; Steenhoff, V.; Agert, C.; Brolo, A. G.

    2017-01-01

    Plasmonic thin film solar cells (modified with metallic nanostructures) often display enhanced light absorption due to surface plasmon resonance (SPR). However, the plasmonic field localization may not be significantly beneficial to improved photocurrent conversion efficiency for all types of cell configurations. For instance, the integration of random metallic nanoparticles (NPs) into thin film solar cells often introduces additional texturing. This texturing might also contribute to enhanced photon-current efficiency. An experimental systematic investigation to decouple both the plasmonic and the texturing contributions is hard to realize for cells modified with randomly deposited metallic nanoparticles. This work presents an experimental and computational investigation of well-defined plasmonic (Ag) nanoparticles, fabricated by nanosphere lithography, integrated to the back contact of hydrogenated amorphous silicon (a-Si:H) solar cells. The size, shape, periodicity and the vertical position of the Ag nanoparticles were well-controlled. The experimental results suggested that a-Si:H solar cells modified with a periodic arrangement of Ag NPs (700 nm periodicity) fabricated just at the top of the metal contact in the back reflector yields the highest improvement in terms of current density (JSC). Finite-difference time-domain (FDTD) simulations also indicated that Ag nanoparticles located at the top of the metal contact in the back reflector is expected to lead to the most efficient light confinement inside the a-Si:H absorber intrinsic layer (i-layer).

  2. Hybrid ZnO nanowire/a-Si:H thin-film radial junction solar cells using nanoparticle front contacts

    NASA Astrophysics Data System (ADS)

    Pathirane, M.; Iheanacho, B.; Tamang, A.; Lee, C.-H.; Lujan, R.; Knipp, D.; Wong, W. S.

    2015-10-01

    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.

  3. 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.

  4. 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).

  5. Nanoimprinted backside reflectors for a-Si:H thin-film solar cells: critical role of absorber front textures.

    PubMed

    Tsao, Yao-Chung; Fisker, Christian; Pedersen, Thomas Garm

    2014-05-05

    The development of optimal backside reflectors (BSRs) is crucial for future low cost and high efficiency silicon (Si) thin-film solar cells. In this work, nanostructured polymer substrates with aluminum coatings intended as BSRs were produced by positive and negative nanoimprint lithography (NIL) techniques, and hydrogenated amorphous silicon (a-Si:H) was deposited hereon as absorbing layers. The relationship between optical properties and geometry of front textures was studied by combining experimental reflectance spectra and theoretical simulations. It was found that a significant height variation on front textures plays a critical role for light-trapping enhancement in solar cell applications. As a part of sample preparation, a transfer NIL process was developed to overcome the problem of low heat deflection temperature of polymer substrates during solar cell fabrication.

  6. 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.

  7. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  8. a-SiCxNy:H thin films for applications in solar cells as passivation and antireflective coatings

    NASA Astrophysics Data System (ADS)

    Swatowska, Barbara; Kluska, Stanisława; Lewińska, Gabriela; Golańska, Julia; Stapiński, Tomasz

    2016-12-01

    Amorphous a-SiCxNy:H thin films may be an alternative to a-Si:N:H coatings which are commonly used in silicon solar cells. This material was obtained by PECVD (13.56 MHz) method. The reaction gases used: silane, methane, nitrogen and ammonia. The structure of the layers were investigated by scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). IR absorption spectra of a-SiCxNy:H layers confirmed the presence of various hydrogen bonds - it is important for passivation of Si structural defects. The ellipsometric measurements were implemented to determine the thickness of layers d, refractive index n, extinction coefficient k and energy gap Eg. The values of the energy gap of a-SiCxNy:H layers are in the range from 1.89 to 4.34 eV. The correlation between energy gap of materials and refractive index was found. Generally the introduction of N and/or C into the amorphous silicon network rapidly increases the Eg values.

  9. 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).

  10. ZnO/a-Si distributed Bragg reflectors for light trapping in thin film solar cells from visible to infrared range

    NASA Astrophysics Data System (ADS)

    Chen, Aqing; Yuan, Qianmin; Zhu, Kaigui

    2016-01-01

    Distributed Bragg reflectors (DBRs) consisting of ZnO and amorphous silicon (a-Si) were prepared by magnetron sputtering method for selective light trapping. The quarter-wavelength ZnO/a-Si DBRs with only 6 periods exhibit a peak reflectance of above 99% and have a full width at half maximum that is greater than 347 nm in the range of visible to infrared. The 6-pair reversed quarter-wavelength ZnO/a-Si DBRs also have a peak reflectance of 98%. Combination of the two ZnO/a-Si DBRs leads to a broader stopband from 686 nm to 1354 nm. Using the ZnO/a-Si DBRs as the rear reflector of a-Si thin film solar cells significantly increases the photocurrent in the spectrum range of 400⿿1000 nm, in comparison with that of the cells with Al reflector. The obtained results suggest that ZnO/a-Si DBRs are promising reflectors of a-Si thin-film solar cells for light trapping.

  11. Manipulating hybrid structures of polymer/a-Si for thin film solar cells

    NASA Astrophysics Data System (ADS)

    Peng, Ying; He, Zhiqun; Diyaf, Adel; Ivaturi, Aruna; Zhang, Zhi; Liang, Chunjun; Wilson, John I. B.

    2014-03-01

    A series of uniform polymer/amorphous silicon hybrid structures have been fabricated by means of solution-casting for polymer and radio frequency excited plasma enhanced chemical vapour deposition for amorphous silicon (a-Si:H). Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) functioned as a photoactive donor, while the silicon layer acted as an acceptor. It is found that matching the hole mobility of the polymer to the electron mobility of amorphous silicon is critical to improve the photovoltaic performance from hybrid cells. A three-layer p-i-n structure of ITO/PEDOT:PSS(200 nm)/i-Si(450 nm)/n-Si(200 nm)/Al with a power conversion efficiency of 4.78% under a standard test condition was achieved.

  12. Manipulating hybrid structures of polymer/a-Si for thin film solar cells

    SciTech Connect

    Peng, Ying; He, Zhiqun E-mail: J.I.B.Wilson@hw.ac.uk; Zhang, Zhi; Liang, Chunjun; Diyaf, Adel; Ivaturi, Aruna; Wilson, John I. B. E-mail: J.I.B.Wilson@hw.ac.uk

    2014-03-10

    A series of uniform polymer/amorphous silicon hybrid structures have been fabricated by means of solution-casting for polymer and radio frequency excited plasma enhanced chemical vapour deposition for amorphous silicon (a-Si:H). Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) functioned as a photoactive donor, while the silicon layer acted as an acceptor. It is found that matching the hole mobility of the polymer to the electron mobility of amorphous silicon is critical to improve the photovoltaic performance from hybrid cells. A three-layer p-i-n structure of ITO/PEDOT:PSS(200 nm)/i-Si(450 nm)/n-Si(200 nm)/Al with a power conversion efficiency of 4.78% under a standard test condition was achieved.

  13. Study and Simulation of the Heterojunction Thin Film Solar Cell a-Si( n)/a-Si( i)/c-Si( p)/a-Si( i)/a-Si( p)

    NASA Astrophysics Data System (ADS)

    Toufik, Zarede; Hamza, Lidjici; Mohamed, Fathi; Achour, Mahrane

    2016-08-01

    In this article, we present a study based on numerical simulation of the electrical characteristics of a thin-film heterojunction solar cell (a-Si( n)/a-Si( i)/c-Si( p)/a-Si( i)/a-Si( p)), using the automat for simulation of hetero-structures (AFORS-Het) software. This cell is composed of four main layers of silicon (Si): (i) 5 nm amorphous silicon doped n, (ii) 100 μm crystalline silicon (substrate) doped p, (iii) 5 nm amorphous silicon doped p, and (iv) 3 nm amorphous silicon intrinsic. This cell has a front and rear metal contact of aluminum and zinc oxide (ZnO) front layer transparent conductive oxide of 80 nm thickness. The simulations were performed at conditions of "One Sun" irradiation with air mass 1.5 (AM1.5), and under absolute temperature T = 300 K. The simulation results have shown a high electrical conversion efficiency of about 30.29% and high values of open circuit voltage V oc = 779 mV. This study has also shown that the studied cell has good quality light absorption on a very broad spectrum.

  14. Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration

    NASA Astrophysics Data System (ADS)

    Huang, Zhiquan

    Spectroscopic ellipsometry (SE) is a non-invasive optical probe that is capable of accurately and precisely measuring the structure of thin films, such as their thicknesses and void volume fractions, and in addition their optical properties, typically defined by the index of refraction and extinction coefficient spectra. Because multichannel detection systems integrated into SE instrumentation have been available for some time now, the data acquisition time possible for complete SE spectra has been reduced significantly. As a result, real time spectroscopic ellipsometry (RTSE) has become feasible for monitoring thin film nucleation and growth during the deposition of thin films as well as during their removal in processes of thin film etching. Also because of the reduced acquisition time, mapping SE is possible by mounting an SE instrument with a multichannel detector onto a mechanical translation stage. Such an SE system is capable of mapping the thin film structure and its optical properties over the substrate area, and thereby evaluating the spatial uniformity of the component layers. In thin film photovoltaics, such structural and optical property measurements mapped over the substrate area can be applied to guide device optimization by correlating small area device performance with the associated local properties. In this thesis, a detailed ex-situ SE study of hydrogenated amorphous silicon (a-Si:H) thin films and solar cells prepared by plasma enhanced chemical vapor deposition (PECVD) has been presented. An SE analysis procedure with step-by-step error minimization has been applied to obtain accurate measures of the structural and optical properties of the component layers of the solar cells. Growth evolution diagrams were developed as functions of the deposition parameters in PECVD for both p-type and n-type layers to characterize the regimes of accumulated thickness over which a-Si:H, hydrogenated nanocrystalline silicon (nc-Si:H) and mixed phase (a

  15. Transparent conductive oxide layer with monolayer closed-pack Al-doped ZnO spheres and their application to a-Si thin-film solar cells.

    PubMed

    Lo, Shih-Shou; Lin, Chen-Yu; Jan, Der-Jun

    2011-09-15

    We report a new (to the best of our knowledge) transparent conductive oxide (TCO) layer with a monolayer of closed-pack Al-doped ZnO (AZO) spheres partly embedded in an AZO thin film. The average transmittance and haze ratio in the wavelength range of 380-800 nm achieves 65% and 55%, respectively, when AZO spheres with a diameter of 500 nm are embedded in a thickness of 240 nm AZO thin films. The a-Si thin-film solar cell with a regular p-i-n TCO structure is demonstrated. Under air mass 1.5 global illumination, conversion efficiencies of 5.6%, a fill factor of 0.55, V(oc) of 0.81 V, and a J(sc) of 2.44 mA/cm² are obtained. The Letter helps us to open up potential applications of a new TCO in advanced solar cells and light-emitting diodes.

  16. 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.

  17. 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.

  18. Recent progress in Si thin film technology for solar cells

    NASA Astrophysics Data System (ADS)

    Kuwano, Yukinori; Nakano, Shoichi; Tsuda, Shinya

    1991-11-01

    Progress in Si thin film technology 'specifically amorphous Si (a-Si) and polycrystalline Si (poly-Si) thin film' for solar cells is summarized here from fabrication method, material, and structural viewpoints. In addition to a-Si, primary results on poly-Si thin film research are discussed. Various applications for a-Si solar cells are mentioned, and consumer applications and a-Si solar cell photovoltaic systems are introduced. New product developments include see-through solar cells, solar cell roofing tiles, and ultra-light flexible solar cells. As for new systems, air conditioning equipment powered by solar cells is described. Looking to the future, the proposed GENESIS project is discussed.

  19. 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.

  20. Preparation of born-doped a-SiC:H thin films by ICP-CVD method and to the application of large-area heterojunction solar cells.

    PubMed

    Jeong, Chaehwan; Kim, Young-Back; Lee, Suk-Ho; Kim, Jin Hyeok

    2010-05-01

    Hydrogenated amorphous silicon carbide (a-SiC:H) film has been widely used as an emitter p layer in solar cells. For the better p layer, wide optical bandgap, and high electrical conductivity should be obtained from the effective method. We prepared the boron-doped a-SiC:H thin films using inductively coupled plasma chemical vapor deposition (ICP-CVD) method and characteristics on the small-area (2 cm x 2 cm) as well as the large-area films (diameter of 100 mm) were shown on it. As a substrate, the n-type (100) oriented CZ c-Si (5.5 approximately 6.5 omega x cm, 650 microm) wafers were used and cleaned by using the reduced RCA method. A silane (SiH4) of 99.999% purity, H2 and 60% hydrogen diluted ethylene (C2H4) was used as source gas for the deposition of intrinsic a-SiC:H films, and then diborane (B2H6), as the doping gas, is added to C2H4 and SiH4/H2 during the deposition of films. The uniformity of thickness and optical bandgap from large-area as-dep. films was at 1.8% and 0.3%, respectively. Heterojunction solar cell with 2 wt%-AZO/p-a-SiC:H/i-a-Si:H/c-Si/Ag structure was fabricated and characterized with diameter of 152.3 mm in this large-area ICP-CVD system. Conversion efficiency of 9.123% was achieved with a practical area of 100 mm x 100 mm, which can show the potentials to the fabrication of the large-area solar cell using ICP-CVD method.

  1. Mechanical Properties of ZTO, ITO, and a-Si:H Multilayer Films for Flexible Thin Film Solar Cells

    PubMed Central

    Hengst, Claudia; Menzel, Siegfried B; Rane, Gayatri K; Smirnov, Vladimir; Wilken, Karen; Leszczynska, Barbara; Fischer, Dustin; Prager, Nicole

    2017-01-01

    The behavior of bi- and trilayer coating systems for flexible a-Si:H based solar cells consisting of a barrier, an electrode, and an absorption layer is studied under mechanical load. First, the film morphology, stress, Young’s modulus, and crack onset strain (COS) were analyzed for single film coatings of various thickness on polyethylene terephthalate (PET) substrates. In order to demonstrate the role of the microstructure of a single film on the mechanical behavior of the whole multilayer coating, two sets of InSnOx (indium tin oxide, ITO) conductive coatings were prepared. Whereas a characteristic grain–subgrain structure was observed in ITO-1 films, grain growth was suppressed in ITO-2 films. ITO-1 bilayer coatings showed two-step failure under tensile load with cracks propagating along the ITO-1/a-Si:H-interface, whereas channeling cracks in comparable bi- and trilayers based on amorphous ITO-2 run through all constituent layers. A two-step failure is preferable from an application point of view, as it may lead to only a degradation of the performance instead of the ultimate failure of the device. Hence, the results demonstrate the importance of a fine-tuning of film microstructure not only for excellent electrical properties, but also for a high mechanical performance of flexible devices (e.g., a-Si:H based solar cells) during fabrication in a roll-to-roll process or under service. PMID:28772609

  2. Mechanical Properties of ZTO, ITO, and a-Si:H Multilayer Films for Flexible Thin Film Solar Cells.

    PubMed

    Hengst, Claudia; Menzel, Siegfried B; Rane, Gayatri K; Smirnov, Vladimir; Wilken, Karen; Leszczynska, Barbara; Fischer, Dustin; Prager, Nicole

    2017-03-01

    The behavior of bi- and trilayer coating systems for flexible a-Si:H based solar cells consisting of a barrier, an electrode, and an absorption layer is studied under mechanical load. First, the film morphology, stress, Young's modulus, and crack onset strain (COS) were analyzed for single film coatings of various thickness on polyethylene terephthalate (PET) substrates. In order to demonstrate the role of the microstructure of a single film on the mechanical behavior of the whole multilayer coating, two sets of InSnOx (indium tin oxide, ITO) conductive coatings were prepared. Whereas a characteristic grain-subgrain structure was observed in ITO-1 films, grain growth was suppressed in ITO-2 films. ITO-1 bilayer coatings showed two-step failure under tensile load with cracks propagating along the ITO-1/a-Si:H-interface, whereas channeling cracks in comparable bi- and trilayers based on amorphous ITO-2 run through all constituent layers. A two-step failure is preferable from an application point of view, as it may lead to only a degradation of the performance instead of the ultimate failure of the device. Hence, the results demonstrate the importance of a fine-tuning of film microstructure not only for excellent electrical properties, but also for a high mechanical performance of flexible devices (e.g., a-Si:H based solar cells) during fabrication in a roll-to-roll process or under service.

  3. Analysis of poly-Si thin film p^+-n-n+ homojunction solar cell and heterojunction solar cell with and without a thin μc-Si layer at the interface of a-Si and poly-Si layers

    NASA Astrophysics Data System (ADS)

    Letha, A. J.; Hwang, H. L.

    2009-05-01

    In this study, new possibilities for higher efficiency poly-Si thin film solar cells are investigated using MEDICI^TM device simulator. The poly-Si p^+-n-n+ thin film solar cell with a thin a-Si p+ layer is found to have higher efficiency than the homojunction p^+-n-n+ cell. Further improvement in efficiency of the heterojunction p^+-n-n+ cell is achieved by introducing a thin μc-Si layer at the interface of a-Si emitter and poly-Si absorber layers. The μc-Si layer at the interface is found to reduce the recombination losses at the interface and improved the fill factor and efficiency of the cell. The photovoltaic parameters of the cell and the absorber layer thickness for optimum efficiency are highly influenced by grain size and passivation at the grain boundary.

  4. Progress in a-SiOx:H thin film solar cells with patterned MgF2 dielectric for top cell of multi-junction system

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Won; Sichanugrist, Porponth; Konagai, Makoto

    2016-07-01

    We successfully designed and experimentally demonstrated an application of patterned MgF2 dielectric material at rear Al-doped ZnO (AZO)/Ag interface in thin film amorphous silicon oxide ( a-SiOx:H) solar cells. When it was realized in practical device process, MgF2 coverage with patterned morphology was employed to allow for current flow between the AZO and Ag against highly resistive MgF2 material. On the basis of the suggested structure, we found an improvement in quantum efficiency of the solar cells with the patterned MgF2. In addition, an enhancement of open circuit voltage ( V oc ) and fill factor ( FF) was observed. A remarkable increase in shunt resistance of the cells with the MgF2 would possibly indicate that the highly resistive MgF2 layer can partly suppress physical shunting across top and bottom electrodes caused by very thin absorber thickness of only 100 nm. The approach showed that our best-performing device revealed an essential improvement in conversion efficiency from 7.83 to 8.01% with achieving markedly high V oc (1.013 V) and FF (0.729). [Figure not available: see fulltext.

  5. 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

  6. Results of some initial space qualification testing on triple junction a-Si and CuInSe2 thin film solar cells

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.; Anspaugh, Bruce E.

    1993-01-01

    A series of environmental tests were completed on one type of triple junction a-Si and two types of CuInSe2 thin film solar cells. The environmental tests include electron irradiation at energies of 0.7, 1.0, and 2.0 MeV, proton irradiation at energies of 0.115, 0.24, 0.3, 0.5, 1.0, and 3.0 MeV, post-irradiation annealing at temperatures between 20 C and 60 C, long term exposure to air mass zero (AM0) photons, measurement of the cells as a function of temperature and illumination intensity, and contact pull strength tests. As expected, the cells are very resistant to electron and proton irradiation. However, when a selected cell type is exposed to low energy protons designed to penetrate to the junction region, there is evidence of more significant damage. A significant amount of recovery was observed after annealing in several of the cells. However, it is not permanent and durable, but merely a temporary restoration, later nullified with additional irradiation. Contact pull strengths measured on the triple junction a-Si cells averaged 667 grams, and pull strengths measured on the Boeing CuInSe2 cells averaged 880 grams. Significant degradation of all cell types was observed after exposure to a 580 hour photon degradation test, regardless of whether the cells had been unirradiated or irradiated (electrons or protons). Although one cell from one manufacturer lost approximately 60 percent of its power after the photon test, several other cells from this manufacturer did not degrade at all.

  7. 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.

  8. 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.

  9. 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.

  10. Preliminary Measurements of Thin Film Solar Cells

    NASA Image and Video Library

    1967-06-21

    George Mazaris, works with an assistant to obtain the preliminary measurements of cadmium sulfide thin-film solar cells being tested in the Space Environmental Chamber at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis’ Photovoltaic Fundamentals Section was investigating thin-film alternatives to the standard rigid and fragile solar cells. The cadmium sulfide semiconductors were placed in a light, metallized substrate that could be rolled or furled during launch. The main advantage of the thin-film solar cells was their reduced weight. Lewis researchers, however, were still working on improving the performance of the semiconductor. The new thin-film solar cells were tested in a space simulation chamber in the CW-6 test cell in the Engine Research Building. The chamber created a simulated altitude of 200 miles. Sunlight was simulated by a 5000-watt xenon light. Some two dozen cells were exposed to 15 minutes of light followed by 15 minutes of darkness to test their durability in the constantly changing illumination of Earth orbit. This photograph was taken for use in a NASA recruiting publication.

  11. High-Rate Fabrication of a-Si-Based Thin-Film Solar Cells Using Large-Area VHF PECVD Processes

    SciTech Connect

    Deng, Xunming; Fan, Qi Hua

    2011-12-31

    The University of Toledo (UT), working in concert with it’s a-Si-based PV industry partner Xunlight Corporation (Xunlight), has conducted a comprehensive study to develop a large-area (3ft x 3ft) VHF PECVD system for high rate uniform fabrication of silicon absorber layers, and the large-area VHF PECVD processes to achieve high performance a-Si/a-SiGe or a-Si/nc-Si tandem junction solar cells during the period of July 1, 2008 to Dec. 31, 2011, under DOE Award No. DE-FG36-08GO18073. The project had two primary goals: (i) to develop and improve a large area (3 ft × 3 ft) VHF PECVD system for high rate fabrication of > = 8 Å/s a-Si and >= 20 Å/s nc-Si or 4 Å/s a-SiGe absorber layers with high uniformity in film thicknesses and in material structures. (ii) to develop and optimize the large-area VHF PECVD processes to achieve high-performance a-Si/nc-Si or a-Si/a-SiGe tandem-junction solar cells with >= 10% stable efficiency. Our work has met the goals and is summarized in “Accomplishments versus goals and objectives”.

  12. 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.

  13. 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.

  14. 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.

  15. Enhancement of optical absorption in silicon thin-film solar cells with metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shi, Bo; Wang, Wei; Yu, Xueqing; Yang, Lili; Xu, Yuanpei

    2017-05-01

    Light trapping structures are a promising method of improving the efficiency of solar cells. We focused on the plasmonic thin-film solar cell. A structure is proposed consisting of an indium tin oxide layer with embedded metal nanoparticles, a hydrogenated amorphous silicon (a-Si:H) layer, and an aluminum (Al) layer. The finite-difference-time-domain (FDTD) method was used to calculate the absorption characteristics of the a-Si:H thin-film solar cells containing nanoparticles. By arranging the material, size, and locations of metal nanoparticles to maximize the scattering and minimize absorption of nanoparticles themselves, the optical absorption in the solar cell is significantly enhanced.

  16. 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.

  17. 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.

  18. 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.

  19. Metastability of a-SiOx:H thin films for c-Si surface passivation

    NASA Astrophysics Data System (ADS)

    Serenelli, L.; Martini, L.; Imbimbo, L.; Asquini, R.; Menchini, F.; Izzi, M.; Tucci, M.

    2017-01-01

    The adoption of a-SiOx:H films obtained by PECVD in heterojunction solar cells is a key to further increase their efficiency, because of its transparency in the UV with respect to the commonly used a-Si:H. At the same time this layer must guarantee high surface passivation of the c-Si to be suitable in high efficiency solar cell manufacturing. On the other hand the application of amorphous materials like a-Si:H and SiNx on the cell frontside expose them to the mostly energetic part of the sun spectrum, leading to a metastability of their passivation properties. Moreover as for amorphous silicon, thermal annealing procedures are considered as valuable steps to enhance and stabilize thin film properties, when performed at opportune temperature. In this work we explored the reliability of a-SiOx:H thin film layers surface passivation on c-Si substrates under UV exposition, in combination with thermal annealing steps. Both p- and n-type doped c-Si substrates were considered. To understand the effect of UV light soaking we monitored the minority carriers lifetime and Sisbnd H and Sisbnd O bonding, by FTIR spectra, after different exposure times to light coming from a deuterium lamp, filtered to UV-A region, and focused on the sample to obtain a power density of 50 μW/cm2. We found a certain lifetime decrease after UV light soaking in both p- and n-type c-Si passivated wafers according to a a-SiOx:H/c-Si/a-SiOx:H structure. The role of a thermal annealing, which usually enhances the as-deposited SiOx passivation properties, was furthermore considered. In particular we monitored the UV light soaking effect on c-Si wafers after a-SiOx:H coating by PECVD and after a thermal annealing treatment at 300 °C for 30 min, having selected these conditions on the basis of the study of the effect due to different temperatures and durations. We correlated the lifetime evolution and the metastability effect of thermal annealing to the a-SiOx:H/c-Si interface considering the evolution

  20. 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.

  1. Opto-electronic properties of P-doped nc-Si–QD/a-SiC:H thin films as foundation layer for all-Si solar cells in superstrate configuration

    SciTech Connect

    Kar, Debjit; Das, Debajyoti

    2016-07-14

    With the advent of nc-Si solar cells having improved stability, the efficient growth of nc-Si i-layer of the top cell of an efficient all-Si solar cell in the superstrate configuration prefers nc-Si n-layer as its substrate. Accordingly, a wide band gap and high conducting nc-Si alloy material is a basic requirement at the n-layer. Present investigation deals with the development of phosphorous doped n-type nanocrystalline silicon quantum dots embedded in hydrogenated amorphous silicon carbide (nc-Si–QD/a-SiC:H) hetero-structure films, wherein the optical band gap can be widened by the presence of Si–C bonds in the amorphous matrix and the embedded high density tiny nc-Si–QDs could provide high electrical conductivity, particularly in P-doped condition. The nc-Si–QDs simultaneously facilitate further widening of the optical band gap by virtue of the associated quantum confinement effect. A complete investigation has been made on the electrical transport phenomena involving charge transfer by tunneling and thermionic emission prevailing in n-type nc-Si–QD/a-SiC:H thin films. Their correlation with different phases of the specific heterostructure has been carried out for detailed understanding of the material, in order to improve its device applicability. The n-type nc-Si–QD/a-SiC:H films exhibit a thermally activated electrical transport above room temperature and multi-phonon hopping (MPH) below room temperature, involving defects in the amorphous phase and the grain-boundary region. The n-type nc-Si–QD/a-SiC:H films grown at ∼300 °C, demonstrating wide optical gap ∼1.86–1.96 eV and corresponding high electrical conductivity ∼4.5 × 10{sup −1}–1.4 × 10{sup −2} S cm{sup −1}, deserve to be an effective foundation layer for the top nc-Si sub-cell of all-Si solar cells in n-i-p structure with superstrate configuration.

  2. Opto-electronic properties of P-doped nc-Si-QD/a-SiC:H thin films as foundation layer for all-Si solar cells in superstrate configuration

    NASA Astrophysics Data System (ADS)

    Kar, Debjit; Das, Debajyoti

    2016-07-01

    With the advent of nc-Si solar cells having improved stability, the efficient growth of nc-Si i-layer of the top cell of an efficient all-Si solar cell in the superstrate configuration prefers nc-Si n-layer as its substrate. Accordingly, a wide band gap and high conducting nc-Si alloy material is a basic requirement at the n-layer. Present investigation deals with the development of phosphorous doped n-type nanocrystalline silicon quantum dots embedded in hydrogenated amorphous silicon carbide (nc-Si-QD/a-SiC:H) hetero-structure films, wherein the optical band gap can be widened by the presence of Si-C bonds in the amorphous matrix and the embedded high density tiny nc-Si-QDs could provide high electrical conductivity, particularly in P-doped condition. The nc-Si-QDs simultaneously facilitate further widening of the optical band gap by virtue of the associated quantum confinement effect. A complete investigation has been made on the electrical transport phenomena involving charge transfer by tunneling and thermionic emission prevailing in n-type nc-Si-QD/a-SiC:H thin films. Their correlation with different phases of the specific heterostructure has been carried out for detailed understanding of the material, in order to improve its device applicability. The n-type nc-Si-QD/a-SiC:H films exhibit a thermally activated electrical transport above room temperature and multi-phonon hopping (MPH) below room temperature, involving defects in the amorphous phase and the grain-boundary region. The n-type nc-Si-QD/a-SiC:H films grown at ˜300 °C, demonstrating wide optical gap ˜1.86-1.96 eV and corresponding high electrical conductivity ˜4.5 × 10-1-1.4 × 10-2 S cm-1, deserve to be an effective foundation layer for the top nc-Si sub-cell of all-Si solar cells in n-i-p structure with superstrate configuration.

  3. Recent technological advances in thin film solar cells

    SciTech Connect

    Ullal, H.S.; Zwelbel, K.; Surek, T.

    1990-03-01

    High-efficiency, low-cost thin film solar cells are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. This paper reviews the substantial advances made by several thin film solar cell technologies, namely, amorphous silicon, copper indium diselenide, cadmium telluride, and polycrystalline silicon. Recent examples of utility demonstration projects of these emerging materials are also discussed. 8 refs., 4 figs.

  4. 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.

  5. Flexible Thin-Film Silicon Solar Cells

    SciTech Connect

    Vijh, Aarohi; Cao, Simon; Mohring, Brad

    2014-01-11

    High fuel costs, environmental concerns and issues of national energy security have brought increasing attention to a distributed generation program for electricity based on solar technology. Rooftop photovoltaic (PV) systems provide distributed generation since the power is consumed at the point of production, thus eliminating the need for costly additional transmission lines. However, most current photovoltaic modules are heavy and require a significant amount of labor and accessory hardware such as mounting frames for installation on rooftops. This makes rooftop systems impractical or cost prohibitive in many instances. Under this project, Xunlight has advanced its manufacturing process for the production of lightweight, flexible thin-film silicon based photovoltaic modules, and has enhanced the reliability and performance of Xunlight’s products. These modules are easily unrolled and adhered directly to standard commercial roofs without mounting structures or integrated directly into roofing membrane materials for the lowest possible installation costs on the market. Importantly, Xunlight has now established strategic alliances with roofing material manufacturers and other OEMs for the development of building integrated photovoltaic roofing and other PV-enabled products, and has deployed its products in a number of commercial installations with these business partners.

  6. 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)

  7. Improvement in optical and structural properties of ZnO thin film through hexagonal nanopillar formation to improve the efficiency of a Si-ZnO heterojunction solar cell

    NASA Astrophysics Data System (ADS)

    Maity, S.; Bhunia, C. T.; Sahu, P. P.

    2016-05-01

    We propose to use ZnO thin film with hexagonal nanopillars deposited on Si substrate to enhance the efficiency of a solar cell. It has been treated chemically and thermally and various crystal orientations have been obtained. X-ray diffraction of ZnO thin film shows relatively high intensity peak at 34.3° angle (0 0 2) compared to other orientations. Photoluminescence measurements also confirm a narrow full width at half maximum peak at 3.3 eV, which is more than that obtained for as-grown (broad emission peak around 3.0 eV). The alignment of nanorod structure made by adding a dopant of 0.15 mole fraction of magnesium increases both photon collection and electron collection efficiency. As a result, the solar cell efficiency is enhanced from 10% to 20%.

  8. 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.

  9. Study of microstructural and optical properties of a-Si:H thin films

    NASA Astrophysics Data System (ADS)

    Jurečka, Stanislav; Müllerová, Jarmila

    2010-12-01

    Undoped amorphous silicon thin films pasivated by hydrogen (a-Si:H) are important for a number of industrial and research applications, especially for optoelectronics, photovoltaics, optical communications, senzorics, laser technology and so on. We experimentally studied properties of the a-Si:H thin films prepared by the plasma-enhanced chemical vapour deposition (PECVD) method. Sample microstructure properties and the effect of the microstructure on optical properties of the a-Si:H thin films deposited by PECVD on glass were analysed. The spectral refractive index, extinction coefficient, and surface morphology were analysed for the series of a-Si:H samples prepared in different technological conditions from H diluted silane plasma. Surface morphology of studied samples was described by the atomic force microscopy (AFM) method. Optical properties of a-Si:H thin films were analysed by numerical optimization of the microstructural and dispersion model of optical parameters relative to the experimental spectral reflectance. The results show that at dilution between 20 and 30 the transition between amorphous and polycrystalline phase occurs. The sample becomes a mixture of amorphous and polycrystalline phase with nano-sized grains and voids with decreasing hydrogen concentration.

  10. 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.

  11. 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.

  12. Performance-improved thin-film a-Si:H/μc-Si:H tandem solar cells by two-dimensionally nanopatterning photoactive layer

    PubMed Central

    2014-01-01

    Tandem solar cells consisting of amorphous and microcrystalline silicon junctions with the top junction nanopatterned as a two-dimensional photonic crystal are studied. Broadband light trapping, detailed electron/hole transport, and photocurrent matching modulation are considered. It is found that the absorptances of both junctions can be significantly increased by properly engineering the duty cycles and pitches of the photonic crystal; however, the photocurrent enhancement is always unevenly distributed in the junctions, leading to a relatively high photocurrent mismatch. Further considering an optimized intermediate layer and device resistances, the optimally matched photocurrent approximately 12.74 mA/cm2 is achieved with a light-conversion efficiency predicted to be 12.67%, exhibiting an enhancement of over 27.72% compared to conventional planar configuration. PMID:24521244

  13. Peeling process of thin-film solar cells using graphene layers

    NASA Astrophysics Data System (ADS)

    Ishikawa, Ryousuke; Kurokawa, Yasuyoshi; Miyajima, Shinsuke; Konagai, Makoto

    2017-08-01

    A novel peeling process for thin-film solar cells using graphene layers was demonstrated. We fabricated amorphous silicon (a-Si) solar cells as substitutes for the undeveloped nanostructured silicon solar cells on graphene layers in order to investigate the solar cell performance after peeling for the first time. The graphene layers functioned as transparent electrodes after the peeling process, even though the series resistance increased after the peeling. Next, we fabricated a silicon nanowire (SiNW) array on graphene layers by a combination of chemical etching and thermal crystallization. Finally, we successfully peeled a SiNW array using graphene layers.

  14. 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.

  15. 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.

  16. 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.

  17. Potential of thin-film solar cell module technology

    NASA Technical Reports Server (NTRS)

    Shimada, K.; Ferber, R. R.; Costogue, E. N.

    1985-01-01

    During the past five years, thin-film cell technology has made remarkable progress as a potential alternative to crystalline silicon cell technology. The efficiency of a single-junction thin-film cell, which is the most promising for use in flat-plate modules, is now in the range of 11 percent with 1-sq cm cells consisting of amorphous silicon, CuInSe2 or CdTe materials. Cell efficiencies higher than 18 percent, suitable for 15 percent-efficient flat plate modules, would require a multijunction configuration such as the CdTe/CuInSe2 and tandem amorphous-silicon (a-Si) alloy cells. Assessments are presented of the technology status of thin-film-cell module research and the potential of achieving the higher efficiencies required for large-scale penetration into the photovoltaic (PV) energy market.

  18. 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.

  19. 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.

  20. Photon upconversion for thin film solar cells

    NASA Astrophysics Data System (ADS)

    de Wild, J.

    2012-09-01

    . For this, another host material (Gd2O2S:Er3+, Yb3+) was characterized and coupling of β-NaYF4 upconverter with a plasmon resonance is investigated. The second part of the research is concerned with application of the upconverter onto solar cells. In this research the β-NaYF4 and Gd2O2S upconverters were applied onto amorphous silicon solar cells (a-Si:H). At first, proof of principle experiments on solar cells with β-NaYF4 upconverter were performed with laser light. I-V curves were measured and an increased response was determined in the upconverter solar cells. Finally, to proof viability of the concept further a set-up was made to concentrate simulated solar light. Concentration of solar light is not uncommon and more real life than laser light. All wavelengths longer than 900 nm were concentrated, which means that the range of the spectrum was much broader than the part that is absorbed by the upconverter. As upconverter material Gd2O2S was applied. Though a large part of the response is due to sub band gap defect absorption an increased response due to the upconverter was measured as well. The upconverter efficiency is thus high enough under moderate concentration of sunlight.

  1. Thin-film absorber for a solar collector

    SciTech Connect

    Wilhelm, W.G.

    1982-02-09

    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.

  2. Determination of Selected Material Properties of Castable Thin Film Polyimides for Applications in Solar Thermal Propulsion

    NASA Astrophysics Data System (ADS)

    Paxton, James P.

    1994-04-01

    Partial contents; This Study will, WHat is a thin film?, An application of Thin Film polyimides, Typical Solar Thermal Rocket Configuration, Benefits of 6FDA +APB Thin Films, Design Parameters for Articles constructed with thin film polyimides, theory, thin film test apparatus, unlaxial test appartus, toggle grip design, computer test panel, experimental procedure, Modulus of Elasticity results, Coefficient of Thermal Expansion results, Conclusions and Recommendations, Acknowledgement.

  3. 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.

  4. 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 %.

  5. 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.

  6. Ag Nanodots Emitters Embedded in a Nanocrystalline Thin Film Deposited on Crystalline Si Solar Cells.

    PubMed

    Park, Seungil; Ryu, Sel Gi; Ji, HyungYong; Kim, Myeong Jun; Peck, Jong Hyeon; Kim, Keunjoo

    2016-06-01

    We fabricated crystalline Si solar cells with the inclusion of various Ag nanodots into the additional emitters of nanocrystallite Si thin films. The fabricated process was carried out on the emitter surface of p-n junction for the textured p-type wafer. The Ag thin films were deposited on emitter surfaces and annealed at various temperatures. The amorphous Si layers were also deposited on the Ag annealed surfaces by hot-wire chemical vapor deposition and then the deposited layers were doped by the second n-type doping process to form an additional emitter. From the characterization, both the Ag nanodots and the deposited amorphous Si thin films strongly reduce photo-reflectances in a spectral region between 200-400 nm. After embedding Ag nanodots in nanocrystallite Si thin films, a conversion efficiency of the sample with added emitter was achieved to 15.1%, which is higher than the 14.1% of the reference sample and the 14.7% of the de-posited sample with a-Si:H thin film after the Ag annealing process. The additional nanocrystallite emitter on crystalline Si with Ag nanodots enhances cell properties.

  7. The challenge of crystalline thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Werner, J. H.; Bergmann, R.; Brendel, R.

    The high production costs of thick high-efficiency crystalline Si solar cells are inhibiting widespread application of photovoltaic devices, amorphous Si suffers from inherent instability. Thus, crystalline thin film Si may offer a chance for low cost and high efficiency cells. The present contribution reviews the status of thin film Si photovoltaics, which have reached efficiencies of above 17 % with single crystalline films of 50 μm thickness using high-efficiency techniques. We discuss the basic problems which have to be solved in the development of a polycrystalline thin film Si cell. The most challenging problem is to control the nucleation and growth of crystalline Si on foreign substrates. While there are some promising results, mainly based on recrystallization techniques for Si deposition on high temperature substrates such as graphite, deposition at low temperatures is still in a very early stage of investigation. Thin film cells need light trapping; we discuss here the principles and compare experiments with results from our simulation program SUNRAYS. Polycrystalline cells contain grain boundaries which have to be passivated in order to achieve high efficiencies. It seems that liquid phase epitaxy opens a new road to intrinsic physical grain boundary passivation. In the last part of our paper, we demonstrate that the technologies of amorphous Si may be useful for the formation of low-temperature charge separating junctions as well as for surface passivation for efficient cells based on thin film crystalline Si.

  8. 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.

  9. Polycrystalline thin-film solar cells and modules

    SciTech Connect

    Ullal, H.S.; Stone, J.L.; Zweibel, K.; Surek, T.; Mitchell, R.L.

    1991-12-01

    This paper describes the recent technological advances in polycrystalline thin-film solar cells and modules. Three thin film materials, namely, cadmium telluride (CdTe), copper indium diselenide (CuInSe{sub 2}, CIS) and silicon films (Si-films) have made substantial technical progress, both in device and module performance. Early stability results for modules tested outdoors by various groups worldwide are also encouraging. The major global players actively involved in the development of the these technologies are discussed. Technical issues related to these materials are elucidated. Three 20-kW polycrystalline thin-film demonstration photovoltaic (PV) systems are expected to be installed in Davis, CA in 1992 as part of the Photovoltaics for Utility-Scale Applications (PVUSA) project. This is a joint project between the US Department of Energy (DOE), Pacific Gas and Electric (PG E), Electric Power Research Institute (EPRI), California Energy Commission (CEC), and a utility consortium.

  10. 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.

  11. 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.

  12. 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%.

  13. 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.

  14. Characterization of the visible photoluminescence from porous a-Si:H and porous a-Si:C:H thin films

    SciTech Connect

    Estes, M.J.; Hirsch, L.R.; Wichart, S.; Moddel, G.

    1996-12-31

    The authors report on the influence of doping, temperature, porosity, and bandgap on the visible photoluminescence properties of anodically-etched porous a-Si:H and a-Si:C:H thin films. Only boron-doped, p-type a-Si:H or a-Si:C:H samples exhibited any visible photoluminescence. The authors see evidence of discrete defect or impurity levels in temperature-dependent luminescence measurements. Unlike in porous crystalline silicon, they see no correlation of luminescence energy with porosity. The authors do, though, observe a correlation of luminescence energy with bandgap of the starting a-Si:C:H films. They discuss the implication of these observations on the nature of the luminescence mechanism.

  15. Surface roughness evolution in the growth of a-Si: H thin films studied by ellipsometry

    NASA Astrophysics Data System (ADS)

    Canillas, A.; Campmany, J.; Andújar, J. L.; Bertran, E.; Morenza, J. L.

    1991-07-01

    In situ real time ellipsometry at 3.4 eV photon energy has been used to analyze the deposition of hydrogenated amorphous silicon (a-Si:H) thin films obtained by RF glow discharge decomposition of silane gas. The study is focused on the evolution of the microstructure during the films growth. The results are explained considering a theoretical model which assumes a homogeneous growth of the a-Si:H below a surface roughness layer which increases 0.5-0.7 nm in thickness during the first 400 nm of film growth. The bulk layer microstructure appears to be homogeneous within 1% of density variations.

  16. 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.

  17. 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.

  18. Calculation of optical band gaps of a-Si:H thin films by ellipsometry and UV-Vis spectrophotometry

    NASA Astrophysics Data System (ADS)

    Qiu, Yijiao; Li, Wei; Wu, Maoyang; Fu, Junwei; Jiang, Yadong

    2010-10-01

    Hydrogenated amorphous silicon (a-Si:H) thin films doped with Phosphorus (P) and Nitrogen (N) were deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). The optical band gaps of the thin films obtained through either changing the gas pressure (P-doped only) or adulterating nitrogen concentration (with fixed P content) were investigated by means of Ellipsometric and Ultraviolet-Visible (UV-Vis) spectroscopy, respectively. Tauc formula was used in calculating the optical band gaps of the thin films in both methods. The results show that Ellipsometry and UV-Vis spectrophotometry can be applied in the research of the optical properties of a-Si:H thin films experimentally. Both methods reflect the variation law of the optical band gaps caused by CVD process parameters, i.e., the optical band gap of the a-Si:H thin films is increased with the rise of the gas pressure or the nitrogen concentration respectively. The difference in optical band gaps of the doped a-Si:H thin films calculated by Ellipsometry or UV-Vis spectrophotometry are not so great that they both can be used to measure the optical band gaps of the thin films in practical applications.

  19. 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.

  20. 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.

  1. 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.

  2. White light emission and optical gains from a Si nanocrystal thin film.

    PubMed

    Wang, Dong-Chen; Hao, Hong-Chen; Chen, Jia-Rong; Zhang, Chi; Zhou, Jing; Sun, Jian; Lu, Ming

    2015-11-27

    We report a Si nanocrystal thin film consisting of free-standing Si nanocrystals, which can emit white light and show positive optical gains for its red, green and blue (RGB) components under ultraviolet excitation. Si nanocrystals with ϕ = 2.31 ± 0.35 nm were prepared by chemical etching of Si powder, followed by filtering. After being mixed with SiO2 sol-gel and thermally annealed, a broadband photoluminescence (PL) from the thin film was observed. The RGB ratio of the PL can be tuned by changing the annealing temperature or atmosphere, which is 1.00/3.26/4.59 for the pure white light emission. The origins of the PL components could be due to differences in oxygen-passivation degree for Si nanocrystals. The results may find applications in white-light Si lasing and Si lighting.

  3. White light emission and optical gains from a Si nanocrystal thin film

    NASA Astrophysics Data System (ADS)

    Wang, Dong-Chen; Hao, Hong-Chen; Chen, Jia-Rong; Zhang, Chi; Zhou, Jing; Sun, Jian; Lu, Ming

    2015-11-01

    We report a Si nanocrystal thin film consisting of free-standing Si nanocrystals, which can emit white light and show positive optical gains for its red, green and blue (RGB) components under ultraviolet excitation. Si nanocrystals with ϕ = 2.31 ± 0.35 nm were prepared by chemical etching of Si powder, followed by filtering. After being mixed with SiO2 sol-gel and thermally annealed, a broadband photoluminescence (PL) from the thin film was observed. The RGB ratio of the PL can be tuned by changing the annealing temperature or atmosphere, which is 1.00/3.26/4.59 for the pure white light emission. The origins of the PL components could be due to differences in oxygen-passivation degree for Si nanocrystals. The results may find applications in white-light Si lasing and Si lighting.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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%.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. Growth temperature effect on a-Si:H thin films studied by constant photocurrent method

    NASA Astrophysics Data System (ADS)

    Wadibhasme, N. A.; Dusane, R. O.

    2013-02-01

    Hydrogenated amorphous silicon (a-Si:H) thin films are synthesized by tuning different process parameters among which substrate temperature of film growth plays an important role in monitoring the device quality of the film. In this paper we have used the constant photocurrent method (CPM) to study the effect of growth temperature on the electronic and optical parameters of a-Si:H films at different photon energies. This technique primarily measures the absorption coefficient which is a result of different electronic transitions that contribute to the photocurrent. The nature of absorption coefficient changes with growth temperature that explicitly provides the information about the density of defect states present in the mid gap of a-Si:H.

  16. Thin-film polycrystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Funghnan, B. W.; Blanc, J.; Phillips, W.; Redfield, D.

    1980-08-01

    Thirty-four new solar cells were fabricated on Wacker Sislo substrates and the AM-1 parameters were measured. A detailed comparison was made between the measurement of minority carrier diffusion length by the OE method and the penetrating light laser scan grain boundary photoresponse linewidth method. The laser scan method has more experimental uncertainty and agrees within 10 to 50% with the QE method. It allows determination of L over a large area. Atomic hydrogen passivation studies continued on Wacker material by three techniques. A method of determining surface recombination velocity, s, from laser scan data was developed. No change in s in completed solar cells after H-plasma treatment was observed within experimental error. H-passivation of bare silicon cars as measured by the new laser scan photoconductivity technique showed very large effects.

  17. 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.

  18. 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.

  19. 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.

  20. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications.

    PubMed

    Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

    2015-07-22

    Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells.

  1. Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

    PubMed Central

    Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

    2015-01-01

    Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells. PMID:28793457

  2. Investigation of the vertical electrical transport in a-Si:H/nc-Si:H superlattice thin films.

    PubMed

    Das, Debajyoti; Kar, Debjit

    2015-07-14

    Tuning the size of silicon nano-crystallites (Si-ncs) has been realized simply by controlling the thickness of the nc-Si:H sub-layer (tnc) in the a-Si:H/nc-Si:H superlattice thin films grown by low temperature plasma processing in PE-CVD. The vertical electrical transport phenomena accomplished in superlattice films have been investigated in order to identify their effective utilization in practical device configuration. The reduced size of the Si-ncs at thinner tnc and the associated band gap widening due to quantum confinement effects generates the Coulomb potential barrier at the a-Si/nc-Si interface which in turn obstructs the transport of charge carriers to the allowed energy states in Si-ncs, leading to the Poole-Frenkel tunneling as the prevailing charge transport mechanism in force. The advantages of the conduction process governed by the Poole-Frenkel mechanism are two-fold. The lower barrier height caused by the a-Si:H sub-layer in the superlattice than the silicon oxide sub-layer in conventional structures enhances the conduction current. Moreover, increasing trapped charges in the a-Si:H sub-layer can arbitrarily increase the current conduction. Accordingly, a-Si:H/nc-Si:H superlattice structures could provide superior electrical transport in stacked layer devices e.g., multi-junction all silicon solar cells.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Sputter-Deposited AlTiO Thin Films for Semi-Transparent Silicon Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Yun; Bang, Ki Su; Lim, Jung Wook

    2014-09-01

    This paper reports on sputter-deposited AlTiO (ATO) thin films and their effects on the performance of semi-transparent silicon thin film solar cells. The electrical resistivity and the transparency of the ATO films depend significantly on the flow ratio of oxygen to argon during the reactive sputtering process. With highly transparent ATO films, transmittances of over 80% were obtained by increasing this flow ratio. When the ATO films were used on silicon substrates, they exhibited an anti-reflection property, where the minimum reflectance at visible light wavelength was decreased to 1.2%. The introduction of ATO thin film layers into solar cells resulted in a 24% increase in transmittance at wavelengths of around 700 nm, due to the film's anti-reflection characteristic. In addition, the color of the cells changed from green to bright red as the ATO layers were adopted. These beneficial effects of the sputter-deposited ATO films suggest an effective pathway towards the semi-transparent silicon thin film solar cells for building-integrated photovoltaic system applications.

  8. 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.

  9. Single crystalline film on glass for thin film solar cells.

    PubMed

    Lin, C H; Yang, Y J; Encinas, E; Chen, W Y; Tsai, J J; Liu, C W

    2009-06-01

    A simple Ge-on-glass metal-oxide-semiconductor solar cell has been demonstrated by wafer bonding and smart-cut. Since single crystalline Ge is directly bonded on glass, the crystalline substrate is not necessary. The metal-oxide-semiconductor structure can be easily fabricated without n and p dopant diffusion or implantation. The reason for low efficiency is discussed, and then the optimized structures are designed by simulation. An outstanding enhancement on efficiency can be achieved with the Si/Ge/Si structure. The best performance can be achieved by optimization of the position of the Ge layer, the thickness of the Ge layer, and the number of the Ge layers. The efficiency of the thin film Si/Ge/Si solar cell with single layer of 30-nm-thick Ge outside the depletion region reaches 15.9%, as compared to the control Si sample of 11.8%. Based on the simulation and technologies, high efficiency thin film solar cells can be demonstrated in the future.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Leakage current and performance loss of thin film solar modules

    NASA Astrophysics Data System (ADS)

    Gossla, Mario; Hälker, Thomas; Krull, Stefan; Rakusa, Fabia; Roth, Florian; Sinicco, Ivan

    2010-08-01

    Due to the system voltage, solar modules in power plants have to withstand continuous high bias voltages between the absorber/conductive layers of the solar module and the grounded mounting structure. Mon et al.1, 2 showed in several publications during the 1980s that the charge transferred by this electrical field is leading to strong electrochemical degradation effects in the modules, both crystalline and thin-film. The bias voltage, especially for thin film modules, can cause transparent conductive oxide (TCO) corrosion via sodium diffusion through the glass together with the presence of water molecules in the TCO/glass interface.3, 4 Based on these previous works, we analyzed the accelerated degradation effects as well as the end of life conditions of different module technologies and module designs. By means of indoor climate chamber and outdoor experiments and based on a simple model we give an example of service life time in terms of electrochemical damage due to high bias voltages caused by the PV system voltage.

  17. New Thin-Film Solar Cells Compared to Normal Solar Cells

    NASA Image and Video Library

    1966-06-21

    Adolph Spakowski, head of the Photovoltaic Fundamentals Section at the National Aeronautics and Space Administration (NASA) Lewis Research Center, illustrated the difference between conventional silicon solar cells (rear panel) and the new thin-film cells. The larger, flexible thin-film cells in the foreground were evaluated by Lewis energy conversion specialists for possible future space use. The conventional solar cells used on most spacecraft at the time were both delicate and heavy. For example, the Mariner IV spacecraft required 28,000 these solar cells for its flyby of Mars in 1964. NASA Lewis began investigating cadmium sulfide thin-film solar cells in 1961. The thin-film cells were made by heating semiconductor material until it evaporated. The vapor was then condensed onto an electricity-producing film only one-thousandth of an inch thick. The physical flexibility of the new thin-film cells allowed them to be furled, or rolled up, during launch. Spakowski led an 18-month test program at Lewis to investigate the application of cadmium sulfide semiconductors on a light metallized substrate. The new thin-film solar cells were tested in a space simulation chamber at a simulated altitude of 200 miles. Sunlight was recreated by a 5000-watt xenon light. Two dozen cells were exposed to 15 minutes of light followed by 15 minutes of darkness to test their durability in the constantly changing illumination of Earth orbit.

  18. 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%.

  19. The structure of a-Si 1-xSn x:H thin films

    NASA Astrophysics Data System (ADS)

    Edwards, A. M.; Fairbanks, M. C.; Newport, R. J.

    1990-12-01

    The doping of a-Si:H with Sn is known to modify the electrical and optical properties of the material. The optical band gap decreases as the doping level is increased, however, there is no insulator-metal transition of the type observed, for example, when transition metals are used as dopants. In order to increase the understanding of the conductivity processes that occur in a-Si:metal:H alloys we have measured the atomic scale structure of a series of a-Si 1- xSn x:H thin-films using EXAFS. Samples were prepared by RF reactive co-sputtering and both Si and Sn K-edge EXAFS examined. The results indicate that the Sn atoms are substituted randomly into the a-Si tetrahedral random network. Both Si and Sn atoms retain fourfold co-ordination over the composition range studied (0⩽ x⩽0.18). In contrast to results obtained using transition metal dopants there is no local modification of the tetrahedral random network.

  20. Hydrogen plasma induced modification of photoluminescence from a-SiNx:H thin films

    NASA Astrophysics Data System (ADS)

    Bommali, R. K.; Ghosh, S.; Vijaya Prakash, G.; Gao, K.; Zhou, S.; Khan, S. A.; Srivastava, P.

    2014-02-01

    Low temperature (250-350 °C) hydrogen plasma annealing (HPA) treatments have been performed on amorphous hydrogenated silicon nitride (a-SiNx:H) thin films having a range of compositions and subsequent modification of photoluminescence (PL) is investigated. The PL spectral shape and peak positions for the as deposited films could be tuned with composition and excitation energies. HPA induced modification of PL of these films is found to depend on the N/Si ratio (x). Upon HPA, the PL spectra show an emergence of a red emission band for x ≤ 1, whereas an overall increase of intensity without change in the spectral shape is observed for x > 1. The emission observed in the Si rich films is attributed to nanoscale a-Si:H inclusions. The enhancement is maximum for off-stoichiometric films (x ˜ 1) and decreases as the compositions of a-Si (x = 0) and a-Si3N4 (x = 1.33) are approached, implying high density of non-radiative defects around x = 1. The diffusion of hydrogen in these films is also analyzed by Elastic Recoil Detection Analysis technique.

  1. Excitation dependent photoluminescence study of Si-rich a-SiNx:H thin films

    NASA Astrophysics Data System (ADS)

    Kumar Bommali, Ravi; Preet Singh, Sarab; Rai, Sanjay; Mishra, P.; Sekhar, B. R.; Vijaya Prakash, G.; Srivastava, P.

    2012-12-01

    We report photoluminescence (PL) investigations on Si-rich amorphous hydrogenated silicon nitride (a-SiNx:H) thin films of different compositions, using three different excitation lasers, viz., 325 nm, 410 nm, and 532 nm. The as-deposited films contain amorphous Si quantum dots (QDs) as evidenced in high resolution transmission electron microscopy images. The PL spectral shape is in general seen to change with the excitation used, thus emphasizing the presence of multiple luminescence centres in these films. It is found that all the spectra so obtained can be deconvoluted assuming Gaussian contributions from defects and quantum confinement effect. Further strength to this assignment is provided by low temperature (300 °C) hydrogen plasma annealing of these samples, wherein a preferential enhancement of the QD luminescence over defect luminescence is observed.

  2. 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.}

  3. 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.

  4. 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.

  5. Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture

    PubMed Central

    Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

    2014-01-01

    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. PMID:25145774

  6. Two-dimensional high efficiency thin-film silicon solar cells with a lateral light trapping architecture

    NASA Astrophysics Data System (ADS)

    Fang, Jia; Liu, Bofei; Zhao, Ying; Zhang, Xiaodan

    2014-08-01

    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.

  7. 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.

  8. Cu(In, Ga)Se2 thin film solar cells grown at low temperatures

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhu, H.; Zhang, L.; Guo, Y.; Niu, X.; Li, Z.; Chen, J.; Liu, Q.; Mai, Y.

    2017-06-01

    Cu(In, Ga)Se2 (CIGS) thin film solar cells were grown on polyimide (PI) and soda lime glass (SLG) substrates at low substrate temperatures between 400 °C and 500 °C. Different material properties of the CIGS thin films and photovoltaic performances of the solar cells were systematically investigated. It is found that the (112), (220)/(204) and (116)/(312) peaks from X-ray diffraction (XRD) patterns show double-peak patterns as the substrate temperature decreases. The CIGS thin films grown on both PI and SLG substrates shows layered structures. The bottom and surficial layers of CIGS thin films display small size polycrystalline grains while the middle layers show large size polycrystalline grains. Both types of CIGS thin film solar cells exhibit similar efficiencies while CIGS thin film solar cells grown on PI substrates show lower open circuit voltage and fill factor but higher short circuit current density, as compared to those of CIGS thin film solar cells on SLG substrates. The highest efficiency of 6.14% has been achieved for the CIGS thin film solar cells on PI with the structure of PI/Mo/CIGS/CdS/i-ZnO/ZnO:Al/Al grid here.

  9. Optimization of photonics for corrugated thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Deparis, Olivier; Vigneron, Jean Pol; Agustsson, Otto; Decroupet, Daniel

    2009-11-01

    The amount of solar energy reaching the active (photovoltaic) layer in a thin-film solar cell can be increased by reducing the Fresnel reflection losses at the interfaces. By using corrugated interfaces (at the wavelength scale), adiabatic propagation of the electromagnetic radiation is achieved over a broad wavelength range throughout the structure, which leads to an increase in the light that is absorbed in the active layer and, ultimately, to the improvement of the photovoltaic conversion efficiency. In this article, we have considered the case of corrugated thin-film solar cell structures and we have studied theoretically the optimization of such structures from the point of view of photonics. The focus was put on periodic pyramidal interface corrugations because they were similar to those existing at the surface of corrugated transparent electrodes on which active layers can be deposited. Because of their technological importance, we chose to work with fluorine-doped tin oxide as front electrode material and with amorphous silicon as active material. Using an original three dimensional transfer matrix method, we solved the electromagnetic wave propagation problem in the general case of laterally periodic stratified media and we compared this solution with effective medium approximated solution. On the basis of typical pyramid sizes, we demonstrated, through numerical simulations, the optimization of the global light energy intake by means of corrugations of increasing complexity. The best structures were found to be based on pyramid arrays having subwavelength periods and aspect ratio values close to one. Typically, a pyramidal structure with base and height both equal to 300 nm led to a global energy intake equal to I =0.98 (integrated over the spectral range 400-710 nm), which represented a 24% improvement in comparison with the global energy intake of a planar structure (I =0.79).

  10. Flexible carbon nanotube/mono-crystalline Si thin-film solar cells

    PubMed Central

    2014-01-01

    Flexible heterojunction solar cells were fabricated from carbon nanotubes (CNTs) and mono-crystalline Si thin films at room temperature. The Si thin films with thickness less than 50 μm are prepared by chemically etching Si wafer in a KOH solution. The initial efficiency of the thin-film solar cell varies from approximately 3% to 5%. After doping with a few drops of 1 M HNO3, the efficiency increases to 6% with a short-circuit current density of 16.8 mA/cm2 and a fill factor of 71.5%. The performance of the solar cells depends on the surface state and thickness of Si thin films, as well as the interface of CNT/Si. The flexible CNT/Si thin-film solar cells exhibit good stability in bending-recovery cycles. PMID:25258617

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Laser treatment of a-SiC:H thin films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Ghica, D.; Mincu, Niculae E.; Stanciu, Catrinel A.; Dinescu, Gheorghe H.; Aldea, E.; Sandu, Viorel; Andrei, A.; Dinescu, Maria; Ferrari, A.; Balucani, M.; Lamedica, G.

    1998-07-01

    Amorphous and hydrogenated (a-SiC:H) as well as crystalline silicon carbide are widespread materials for optoelectronic applications. In this paper, we studied the effect of laser/RF plasma jet treatment of a-SiC:H thin films deposited by Plasma Enhanced Chemical Vapor Deposition, on Si wafers. A Nd:YAG laser ((lambda) equals 1.06 micrometers , tFWHM equals 14 ns, E0 equals 0.015 J/pulse) was used with a fluence of 4 mJ/cm2 incident on the sample, the number of pulses being varied. Plasma treatments were performed in a plasma jet generated by a capacity coupled RF discharge in N2. Different analysis techniques were used to investigate the films, before and after the irradiation: X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. We followed the modification of their structure and composition as an effect of the laser/plasma treatment. A comparison with the excimer and also with the RF treatments was performed.

  2. FT-IR analysis of high temperature annealing effects in a-SiC:H thin films

    NASA Astrophysics Data System (ADS)

    Frischmuth, Tobias; Schneider, Michael; Grille, Thomas; Schmid, U.

    2017-06-01

    Hydrogenated amorphous SiC (a-SiC:H) is an attractive material for MEMS applications where high robustness or operation in harsh environments is targeted. In previous publications, it was demonstrated, that the properties of a-SiC:H thin films can be tailored over a wide range by changing the auxiliary table excitation power of a dual plasma source deposition process using an inductively coupled plasma-enhanced chemical vapour deposition system. In this work, the annealing behavior of dual plasma source deposited a-SiC:H thin films under argon atmosphere is investigated by using Fourier transform infrared (FT-IR) spectroscopy for chemical analysis. All investigated layers show a decrease of hydrogen containing bonds (X-Hx) and an increase of Si-C bonds with increasing annealing temperature in the FT-IR spectrum. This behaviour is directly linked to the effusion of hydrogen from the thin films at elevated temperatures. In addition, films deposited at higher auxiliary plasma power show more X-Hx and less Si-C bonds, indicating a higher hydrogen amount in those films. All layers shrink with increasing annealing temperature due to the effusion of hydrogen with a stronger shrink at higher PT values caused by the increased hydrogen amount. This shrink also leads to a densification of the thin films.

  3. 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.

  4. Simulated Space Environmental Effects on Thin Film Solar Array Components

    NASA Technical Reports Server (NTRS)

    Finckenor, Miria; Carr, John; SanSoucie, Michael; Boyd, Darren; Phillips, Brandon

    2017-01-01

    The Lightweight Integrated Solar Array and Transceiver (LISA-T) experiment consists of thin-film, low mass, low volume solar panels. Given the variety of thin solar cells and cover materials and the lack of environmental protection typically afforded by thick coverglasses, a series of tests were conducted in Marshall Space Flight Center's Space Environmental Effects Facility to evaluate the performance of these materials. Candidate thin polymeric films and nitinol wires used for deployment were also exposed. Simulated space environment exposures were selected based on SSP 30425 rev. B, "Space Station Program Natural Environment Definition for Design" or AIAA Standard S-111A-2014, "Qualification and Quality Requirements for Space Solar Cells." One set of candidate materials were exposed to 5 eV atomic oxygen and concurrent vacuum ultraviolet (VUV) radiation for low Earth orbit simulation. A second set of materials were exposed to 1 MeV electrons. A third set of samples were exposed to 50, 100, 500, and 700 keV energy protons, and a fourth set were exposed to >2,000 hours of near ultraviolet (NUV) radiation. A final set was rapidly thermal cycled between -55 and +125degC. This test series provides data on enhanced power generation, particularly for small satellites with reduced mass and volume resources. Performance versus mass and cost per Watt is discussed.

  5. Simulated Space Environmental Effects on Thin Film Solar Array Components

    NASA Technical Reports Server (NTRS)

    Finckenor, Miria; Carr, John; SanSoucie, Michael; Boyd, Darren; Phillips, Brandon

    2017-01-01

    The Lightweight Integrated Solar Array and Transceiver (LISA-T) experiment consists of thin-film, low mass, low volume solar panels. Given the variety of thin solar cells and cover materials and the lack of environmental protection afforded by typical thick coverglasses, a series of tests were conducted in Marshall Space Flight Center's Space Environmental Effects Facility to evaluate the performance of these materials. Candidate thin polymeric films and nitinol wires used for deployment were also exposed. Simulated space environment exposures were selected based on SSP 30425 rev. B, "Space Station Program Natural Environment Definition for Design" or AIAA Standard S-111A-2014, "Qualification and Quality Requirements for Space Solar Cells." One set of candidate materials were exposed to 5 eV atomic oxygen and concurrent vacuum ultraviolet (VUV) radiation for low Earth orbit simulation. A second set of materials were exposed to 1 MeV electrons. A third set of samples were exposed to 50, 500, and 750 keV energy protons, and a fourth set were exposed to >2,000 hours of ultraviolet radiation. A final set was rapidly thermal cycled between -50 and +120 C. This test series provides data on enhanced power generation, particularly for small satellites with reduced mass and volume resources. Performance versus mass and cost per Watt is discussed.

  6. Simulated Space Environmental Effects on Thin Film Solar Array Components

    NASA Technical Reports Server (NTRS)

    Finckenor, Miria; Carr, John; SanSoucie, Michael; Boyd, Darren; Phillips, Brandon

    2017-01-01

    The Lightweight Integrated Solar Array and Transceiver (LISA-T) experiment consists of thin-film, low mass, low volume solar panels. Given the variety of thin solar cells and cover materials and the lack of environmental protection typically afforded by thick coverglasses, a series of tests were conducted in Marshall Space Flight Center's Space Environmental Effects Facility to evaluate the performance of these materials. Candidate thin polymeric films and nitinol wires used for deployment were also exposed. Simulated space environment exposures were selected based on SSP 30425 rev. B, "Space Station Program Natural Environment Definition for Design" or AIAA Standard S-111A-2014, "Qualification and Quality Requirements for Space Solar Cells." One set of candidate materials were exposed to 5 eV atomic oxygen and concurrent vacuum ultraviolet (VUV) radiation for low Earth orbit simulation. A second set of materials were exposed to 1 MeV electrons. A third set of samples were exposed to 50, 100, 500, and 700 keV energy protons, and a fourth set were exposed to >2,000 hours of near ultraviolet (NUV) radiation. A final set was rapidly thermal cycled between -55 and +125 C. This test series provides data on enhanced power generation, particularly for small satellites with reduced mass and volume resources. Performance versus mass and cost per Watt is discussed.

  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. Characterisation of photovoltaic modules based on thin film solar cells in environmental operating conditions of Algerian Sahara

    NASA Astrophysics Data System (ADS)

    Agroui, K.; Hadj Mahammed, I.; Hadj Arab, A.; Belghachi, A.

    2008-08-01

    This paper summarizes the electrical and thermal characterizations of thin film PV modules based on amorphous triple junctions (3J: a-Si) and Copper Indium Selenide (CIS) thin film solar cells. Tests are operated in outdoor exposure and under natural sunlight of Ghardaia, Algeria) as specific desert climate environment, characterized by high irradiation and temperature levels. Data acquired from Environmental Operating Conditions (EOC) was converted into solar module output characteristics at Standard Test Conditions (STC) by using three method suggested by Anderson and Mermoud as well as the equations already standardized as IEC 60891. Then, based on the investigation results of the conversion equations, differences among the converting methods (range of application, specificity of solar cell material, and experimental test conditions) were studied.

  10. 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.

  11. 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.

  12. 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

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Increased upconversion performance for thin film solar cells: a trimolecular composition

    PubMed Central

    Cheng, Yuen Yap; Nattestad, Andrew; Schulze, Tim F.; MacQueen, Rowan W.; Fückel, Burkhard; Lips, Klaus; Wallace, Gordon G.; Khoury, Tony; Crossley, Maxwell J.

    2016-01-01

    Photochemical upconversion based on triplet–triplet annihilation (TTA-UC) is employed to enhance the short-circuit currents generated by two varieties of thin-film solar cells, a hydrogenated amorphous silicon (a-Si:H) solar cell and a dye-sensitized solar cell (DSC). TTA-UC is exploited to harvest transmitted sub-bandgap photons, combine their energies and re-radiate upconverted photons back towards the solar cells. In the present study we employ a dual-emitter TTA-UC system which allows for significantly improved UC quantum yields as compared to the previously used single-emitter TTA systems. In doing so we achieve record photo-current enhancement values for both the a-Si:H device and the DSC, surpassing 10–3 mA cm–2 sun–2 for the first time for a TTA-UC system and marking a record for upconversion-enhanced solar cells in general. We discuss pertinent challenges of the TTA-UC technology which need to be addressed in order to achieve its viable device application. PMID:28791105

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates

    PubMed Central

    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. PMID:23277871

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Enhancing light trapping properties of thin film solar cells by plasmonic effect of silver nanoparticles.

    PubMed

    Jung, Junhee; Ha, Kyungyeon; Cho, Jaehyun; Ahn, Shihyun; Park, Hyeongsik; Hussain, Shahzada Qamar; Choi, Mansoo; Yi, Junsin

    2013-12-01

    The preparation of thin film silicon solar cells containing Ag nanoparticles is reported in this article. Ag nanoparticles were deposited on fluorine doped tin oxide coated glass substrates by the evaporation and condensation method. a-Si:H solar cells were deposited on these substrates by cluster type plasma enhanced chemical vapor deposition. We discuss the double textured surface effect with respect to both the surface morphology of the substrate and the plasmonic effect of the Ag nanoparticles. Ag nanoparticles of various sizes from 10 to 100 nm were deposited. The haze values of the Ag embedded samples increased with increasing particle size whereas the optical transmittance decreased at the same conditions. The solar cell with the 30 nm size Ag nanoparticles showed a short circuit current density of 12.97 mA/cm2, which is 0.53 mA/cm2 higher than that of the reference solar cell without Ag nanoparticles, and the highest quantum efficiency for wavelengths from 550 to 800 nm. When 30 nm size nanoparticles were employed, the conversion efficiency of the solar cell was increased from 6.195% to 6.696%. This study reports the application of the scattering effect of Ag nanoparticles for the improvement of the conversion efficiency of amorphous silicon solar cells.

  12. 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.

  13. Patterned ion beam implantation of Co ions into a SiO2 thin film via ordered nanoporous alumina masks.

    PubMed

    Guan, Wei; Ghatak, Jay; Peng, Yong; Peng, Nianhua; Jeynes, Chris; Inkson, Beverley; Möbus, Günter

    2012-02-03

    Spatially patterned ion beam implantation of 190 keV Co(+) ions into a SiO(2) thin film on a Si substrate has been achieved by using nanoporous anodic aluminum oxide with a pore diameter of 125 nm as a mask. The successful synthesis of periodic embedded Co regions using pattern transfer is demonstrated for the first time using cross-sectional (scanning) transmission electron microscopy (TEM) in combination with analytical TEM. Implanted Co regions are found at the correct relative lateral periodicity given by the mask and at a depth of about 120 nm.

  14. Spectroscopic and microscopic studies of self-assembled nc-Si/a-SiC thin films grown by low pressure high density spontaneous plasma processing.

    PubMed

    Das, Debajyoti; Kar, Debjit

    2014-12-14

    In view of suitable applications in the window layer of nc-Si p-i-n solar cells in superstrate configuration, the growth of nc-Si/a-SiC composite films was studied, considering the trade-off relation between individual characteristics of its a-SiC component to provide a wide optical-gap and electrically conducting nc-Si component to simultaneously retain enough crystalline linkages to facilitate proper crystallization to the i-nc-Si absorber-layer during its subsequent growth. Self-assembled nc-Si/a-SiC thin films were spontaneously grown by low-pressure planar inductively coupled plasma CVD, operating in electromagnetic mode, providing high atomic-H density. Spectroscopic simulations of ellipsometry and Raman data, and systematic chemical and structural analysis by XPS, TEM, SEM and AFM were performed. Corresponding to optimized inclusion of C essentially incorporated as Si-C bonds in the network, the optical-gap of the a-SiC component widened, void fraction including the incubation layer thickness reduced. While the bulk crystallinity decreased only marginally, Si-ncs diminished in size with narrower distribution and increased number density. With enhanced C-incorporation, formation of C-C bonds in abundance deteriorates the Si continuous bonding network and persuades growth of an amorphous dominated silicon-carbon heterostructure containing high-density tiny Si-ncs. Stimulated nanocrystallization identified in the Si-network, induced by a limited amount of carbon incorporation, makes the material most suitable for applications in nc-Si solar cells. The novelty of the present work is to enable spontaneous growth of self-assembled superior quality nc-Si/a-SiC thin films and simultaneous spectroscopic simulation-based optimization of properties for utilization in devices.

  15. 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.

  16. Characterization of ion-assisted induced absorption in A-Si thin-films used for multivariate optical computing

    NASA Astrophysics Data System (ADS)

    Nayak, Aditya B.; Price, James M.; Dai, Bin; Perkins, David; Chen, Ding Ding; Jones, Christopher M.

    2015-06-01

    Multivariate optical computing (MOC), an optical sensing technique for analog calculation, allows direct and robust measurement of chemical and physical properties of complex fluid samples in high-pressure/high-temperature (HP/HT) downhole environments. The core of this MOC technology is the integrated computational element (ICE), an optical element with a wavelength-dependent transmission spectrum designed to allow the detector to respond sensitively and specifically to the analytes of interest. A key differentiator of this technology is it uses all of the information present in the broadband optical spectrum to determine the proportion of the analyte present in a complex fluid mixture. The detection methodology is photometric in nature; therefore, this technology does not require a spectrometer to measure and record a spectrum or a computer to perform calculations on the recorded optical spectrum. The integrated computational element is a thin-film optical element with a specific optical response function designed for each analyte. The optical response function is achieved by fabricating alternating layers of high-index (a-Si) and low-index (SiO2) thin films onto a transparent substrate (BK7 glass) using traditional thin-film manufacturing processes (e.g., ion-assisted e-beam vacuum deposition). A proprietary software and process are used to control the thickness and material properties, including the optical constants of the materials during deposition to achieve the desired optical response function. The ion-assisted deposition is useful for controlling the densification of the film, stoichiometry, and material optical constants as well as to achieve high deposition growth rates and moisture-stable films. However, the ion-source can induce undesirable absorption in the film; and subsequently, modify the optical constants of the material during the ramp-up and stabilization period of the e-gun and ion-source, respectively. This paper characterizes the unwanted

  17. Aluminum recycling from reactor walls: A source of contamination in a-Si:H thin films

    SciTech Connect

    Longeaud, C.; Ray, P. P.; Bhaduri, A.; Daineka, D.; Johnson, E. V.; Roca i Cabarrocas, P.

    2010-11-15

    In this article, the authors investigate the contamination of hydrogenated amorphous silicon thin films with aluminum recycled from the walls and electrodes of the deposition reactor. Thin films of hydrogenated amorphous silicon were prepared under various conditions by a standard radio frequency plasma enhanced chemical vapor deposition process in two reactors, the chambers of which were constructed of either aluminum or stainless steel. The authors have studied the electronic properties of these thin films and have found that when using an aluminum reactor chamber, the layers are contaminated with aluminum recycled from the chamber walls and electrode. This phenomenon is observed almost independently of the deposition conditions. The authors show that this contamination results in slightly p-doped films and could be detrimental to the deposition of device grade films. The authors also propose a simple way to control and eventually suppress this contamination.

  18. 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.

  19. 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.

  20. Nanosized Structural Anti-Reflection Layer for Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Han, Kang-Soo; Shin, Ju-Hyeon; Kim, Kang-In; Lee, Heon

    2011-02-01

    A nanosized pattern layer was formed on the front surface (glass side) of the thin film solar cell using nanoimprint lithography with a Ni based moth-eye imprint mold in order to increase the total conversion efficiency of the amorphous silicon based thin film solar cell. The imprinted pattern layer had nanosized protrusions, which suppressed the reflection of light on the glass surfaces. The nanopatterns were formed using a methacryloxypropyl terminated poly(dimethylsiloxane) (MPDMS) based hard polymeric resin. The reflectance of the thin film solar cell significantly decreased because of the nanosized structural anti-reflection layer, and the total conversion efficiency of the cell increased about 3% compared to the identical solar cell without the nanosized pattern layer. Moreover, the surface exhibited a hydrophobic nature because of the surface nanopatterns and the self-assembled monolayer coating, and this hydrophobicity provided the solar cell with a self-cleaning functionality.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Parameter variation of the one-diode model of a-Si and a- Si/μc-Si solar cells for modeling light-induced degradation

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    For analyzing the long-term behavior of thin film a-Si/μc-Si photovoltaic modules, it is important to observe the light-induced degradation (LID) in dependence of the temperature for the parameters of the one-diode model for solar cells. According to the IEC 61646 standard, the impact of LID on module parameters of these thin film cells is determined at a constant temperature of 50°C with an irradiation of 1000 W/m2 at open circuit conditions. Previous papers examined the LID of thin film a-Si cells with different temperatures and some others are about a-Si/μc-Si. In these previous papers not all parameters of the one-diode model are examined. We observed the serial resistance (Rs), parallel resistance (Rp), short circuit current (Isc), open circuit voltage (Uoc), the maximum power point (MPP: Umpp, Impp and Pmpp) and the diode factor (n). Since the main reason for the LID of silicon-based thin films is the Staebler Wronski effect in the a-Si part of the cell, the temperature dependence of the healing of defects for all parameters of the one-diode model is also taken into account. We are also measuring modules with different kind of transparent conductive oxides: In a-Si thin film solar cells fluorine-doped tin oxide (FTO) is used and for thin film solar cells of a-Si/μc-Si boron- doped zinc oxide is used. In our work we describe an approach for transferring the parameters of a one-diode model for tandem thin film solar cells into the one-diode model for each part of the solar cell. The measurement of degradation and regeneration at higher temperatures is the necessary base for optimization of the different silicon-based thin films in warm hot climate.

  7. 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.

  8. 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.

  9. 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.

  10. Formation of Tio2 Thin Film for Dye-Sensitized Solar Cell Application Using Electrophoresis Deposition

    NASA Astrophysics Data System (ADS)

    Nuryadi, Ratno; Akbar, Zico Alaia; Wargadipura, Agus Hadi S.; Gunlazuardi, Jarnuzi

    2010-10-01

    One of important processes on the fabrication of dye-sensitized solar cell (DSSC) is formation of TiO2 thin film. Thickness of TiO2 thin film is needed to be controlled in order to obtain optimum TiO2 thickness. Electrophoresis deposition is simple method for thin film deposition which enable us to control the thickness of thin film. In this work, the formation of TiO2 thin film on indium-doped tin oxide (ITO) glass using electrophoresis deposition is numerically and experimentally studied. We have succeeded to control the thickness of TiO2 thin film by changing of electrophoresis applied voltage and deposition time. In the experiment, TiO2 particles were suspended into isopropyl alcohol solution. Mg(NO3)2 was added to the solution in order to obtain the stable solution for electrophoresis. We found numerically that the Mg(NO3)2 in the range from 10-6 M to 10-4 M, is appropriate condition for the electrophoresis deposition. Using this method, we have fabricated DSSC device and study the effect of TiO2 thickness on DSSCs characteristic. Our results shows that the electrophoresis is not only essential for DSSC application but also for the other devices with a given thickness of TiO2 film.

  11. 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.

  12. 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.

  13. Quick design of high efficiency light trapping nanostructures for thin film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Guo, Xiaowei; Wang, Dashuai; Liu, Bang; Zhou, Yong; Li, Shaorong

    2017-07-01

    Photonic nanostructures are now widely investigated as light trapping textures to achieve significant absorption in thin film solar cells. In this paper, we quickly designed a high efficiency photonic structure for thin film silicon solar cells. Based on the coupled mode theory, we compared classic lattice photonic structures and demonstrated triangular lattice structure exhibits better light trapping performance. Through analysis of short circuit current density, unit cells with heart-pentagon polygon arrangement were verified to offer superior absorption in entire silicon absorption spectrum. Finally, the comparisons with other reported textures validated our design.

  14. Enhancing the driving field for plasmonic nanoparticles in thin-film solar cells.

    PubMed

    Santbergen, Rudi; Tan, Hairen; Zeman, Miro; Smets, Arno H M

    2014-06-30

    The scattering cross-section of a plasmonic nanoparticle is proportional to the intensity of the electric field that drives the plasmon resonance. In this work we determine the driving field pattern throughout a complete thin-film silicon solar cell. Our simulations reveal that by tuning of the thicknesses of silicon and transparent conductive oxide layers the driving field intensity experienced by an embedded plasmonic nanoparticle can be enhanced up to a factor of 14. This new insight opens the route towards more efficient plasmonic light trapping in thin-film solar cells.

  15. 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.

  16. 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

  17. Silicon solar cell performance deposited by diamond like carbon thin film ;Atomic oxygen effects;

    NASA Astrophysics Data System (ADS)

    Aghaei, Abbas Ail; Eshaghi, Akbar; Karami, Esmaeil

    2017-09-01

    In this research, a diamond-like carbon thin film was deposited on p-type polycrystalline silicon solar cell via plasma-enhanced chemical vapor deposition method by using methane and hydrogen gases. The effect of atomic oxygen on the functioning of silicon coated DLC thin film and silicon was investigated. Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the structure and morphology of the DLC thin film. Photocurrent-voltage characteristics of the silicon solar cell were carried out using a solar simulator. The results showed that atomic oxygen exposure induced the including oxidation, structural changes, cross-linking reactions and bond breaking of the DLC film; thus reducing the optical properties. The photocurrent-voltage characteristics showed that although the properties of the fabricated thin film were decreased after being exposed to destructive rays, when compared with solar cell without any coating, it could protect it in atomic oxygen condition enhancing solar cell efficiency up to 12%. Thus, it can be said that diamond-like carbon thin layer protect the solar cell against atomic oxygen exposure.

  18. Effects of intermediate plasmonic structures on the performance of ultra-thin-film tandem solar cells

    NASA Astrophysics Data System (ADS)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2017-02-01

    Although solar cells can meet the increasing demand for energy of modern world, their usage is not as widespread as expected because of their high production cost and low efficiency. Thin-film and ultra-thin-film solar cells with single and multiple active layers are being investigated to reduce cost. Additionally, multiple active layers of different energy bandgaps are used in tandem in order to absorb the solar spectra more efficiently. However, the efficiency of ultra-thin-film tandem solar cells may suffer significantly mainly because of low photon absorption and current mismatch between active layers. In this work, we study the effects of intermediate plasmonic structures on the performance of ultra-thin-film tandem solar cells. We consider three structures| each with a top amorphous silicon layer and a bottom micro-crystalline silicon layer, and an intermediate plasmonic layer between them. The intermediate layer is either a metal layer with periodic holes or periodic metal strips or periodic metal nano-clusters. Using a finite difference time domain technique for incident AM 1.5 solar spectra, we show that these intermediate layers help to excite different plasmonic and photonic modes for different light polarizations, and thereby, increase the absorption of light significantly. We find that the short-circuit current density increases by 12%, 6%, and 9% when the intermediate plasmonic structure is a metal hole-array, strips, and nano-clusters, respectively, from that of a structure that does not have the intermediate plasmonic layer.

  19. Ultrafast Lasers Improve the Efficiency of CIS Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Heise, Gerhard; Heiss, Andreas; Vogt, Helmut; Huber, Heinz P.

    CIS (Cu(In,Ga)(S,Se)2) thin film solar cells show a high potential to achieve the efficiencies of Si wafer-based solar cells. The commonly applied patterning processes for the integrated interconnects are based on nanosecond laser ablation and mechanical scribing. Both methods introduce damages on the thin films by thermal effects and mechanical forces. By picosecond laser processing we realized all three patterning steps to the monolithic thin films CIS modules, namely the separation of the molybdenum back electrode, the absorber and the ZnO font electrode (P1, P2 and P3 respectively). We achieved an efficiency of 14.7% for 300 x 300 mm2 modules.

  20. 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.

  1. Roll to roll fabrication of thin film silicon solar cells on nano-textured substrates.

    PubMed

    Soppe, W J; Borg, H; Van Aken, B B; Devilee, C; Dörenkämper, M; Goris, M; Heijna, M C R; Löffler, J; Peeters, P

    2011-12-01

    ECN is developing a novel fabrication process for thin film silicon solar cells on steel foil. Key features in this process are: (1) application of an insulating barrier layer which enables monolithic interconnection and texturization of the rear contact with submicron structures for light trapping; (2) Si deposition with remote, linear PECVD; (3) series interconnection by laser scribing and printing after deposition of all layers, which reduces the total number of process steps. The barrier layer is essential for the monolithic series interconnection of cells, but we show that it also enables optimum light trapping in the solar cells. We can fabricate any arbitrary sub-micron surface profile by hot embossing the barrier layer. For deposition of doped and intrinsic silicon layers we use novel remote, linear plasma sources, which are excellently suited for continuous roll-to-roll processing. We have been able to fabricate device-quality amorphous and microcrystalline silicon layers with these sources. The first nip a-Si cells were made on steel substrates with flat barrier layer and had initial efficiencies of 6.3%, showing the potential of the concept.

  2. Amorphous-silicon thin-film heterojunction solar cells

    SciTech Connect

    Cretella, M. C.; Gregory, J. A.; Sandstrom, D. B.; Paul, W.

    1981-01-01

    The investigation of amorphous silicon materials at MTSEC has had two major thrusts: (1) to improve the amorphous material, i.e., obtain a low state density in the gap, improve the carrier collection depth and diminish non-radiative recombinations; and (2) to attempt to understand and improve on the limitations of the junction devices while evaluating the amorphous silicon materials. In the first of these efforts, the investigation has continued to examine the modifications to the a-Si(H) network by alloying silicon with other group IVA elements, either in binary or ternary compositions, and/or by replacing the hydrogenation for defect compensation with a combination of hydrogenation and alkylation or hydrogenation and halogenation. The doped junction layers are being examined in an attempt to determine the limiting characteristics of the junctions in solar cell devices of these amorphous materials. Amorphous alloys of Si-Ge, Si-C, Si-Sn were prepared as well as ternary compositions of Si-Ge-C and Si-Sn-C. In addition, Na vapor was added to the gas feed to deposit a-Si(Na, H) films, and to prepare Si-Sn, fluoride was added along with the tin by vapor additions of SnF/sub 4/ to the gas feed. The optical properties of these materials were measured, and structural and compositional information was obtained from the IR vibrational spectra using the scanning electron microscope and from analyses using scanning Auger microscopy. Electrical measurements have included the dark conductivity and the photo conductivity under room fluorescent light and at AM1 conditions. With alloys that displayed promising photoconductive properties n-i-p devices were prepared to assess the solar cell properties. Details are presented. (WHK)

  3. Al Thermal Diffusion in a-Si1-xCx:H Thin Film Studied by XAFS

    SciTech Connect

    Prado, R. J.; Carreno, M. N. P.; Pereyra, I.

    2007-02-02

    In this work the local structure around the aluminium atoms, diffused by thermal annealing in a-SiC:H thin films was analyzed by x-ray absorption near edge structure (XANES), aiming to obtain information about the Al ordering after annealing. The thermal annealing of the films was performed in ultra high-vacuum (UHV), in order to avoid Al oxidation. The XANES spectra were obtained in-situ at the Al K-edge (1559 eV), immediately after the annealing process, showing that Al diffusion clearly takes place for carbon rich films. The theoretical simulation of these spectra shows that the Al in carbon rich a-SiC:H has structural order similar to that of c-Al4C3.

  4. Al Thermal Diffusion in a-Si1-xCx:H Thin Film Studied by XAFS

    NASA Astrophysics Data System (ADS)

    Prado, R. J.; Fantini, M. C. A.; Carreño, M. N. P.; Pereyra, I.; Flank, A. M.

    2007-02-01

    In this work the local structure around the aluminium atoms, diffused by thermal annealing in a-SiC:H thin films was analyzed by x-ray absorption near edge structure (XANES), aiming to obtain information about the Al ordering after annealing. The thermal annealing of the films was performed in ultra high-vacuum (UHV), in order to avoid Al oxidation. The XANES spectra were obtained in-situ at the Al K-edge (1559 eV), immediately after the annealing process, showing that Al diffusion clearly takes place for carbon rich films. The theoretical simulation of these spectra shows that the Al in carbon rich a-SiC:H has structural order similar to that of c-Al4C3.

  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. 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.

  7. 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.

  8. Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

    PubMed

    Ram, Sanjay K; Desta, Derese; Rizzoli, Rita; Bellettato, Michele; Lyckegaard, Folmer; Jensen, Pia B; Jeppesen, Bjarke R; Chevallier, Jacques; Summonte, Caterina; Larsen, Arne Nylandsted; Balling, Peter

    2017-06-01

    Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl. Subsequently, the solar cells are detached from the substrate by dissolution of the sacrificial NaCl layer in water and then transferred onto a plastic sheet, with a resultant post-transfer efficiency of 9%. The light-trapping effect of the surface nanotextures originating from the NaCl layer on the overlying solar cell is studied theoretically and experimentally. The enhanced light absorption in the solar cells on NaCl-coated substrates leads to significant improvement in the photocurrent and energy-conversion efficiency in solar cells with both 350 and 100 nm thick absorber layers, compared to flat-substrate solar cells. Efficient transferable thin-film solar cells hold a vast potential for widespread deployment of off-grid photovoltaics and cost reduction.

  9. Integration of solar sail and thin film solar cell using spectrum splitting technology for deep space exploration

    NASA Astrophysics Data System (ADS)

    Feng, Yudong; Zuo, Huaping; Wang, Zhimin

    It is very important to lighten weight for deep space exploration. Thin film type spacecrafts like solar sails may be the good choice. Due to the favourable photoelectric effect in weak light and light weight, flexible thin film solar sell will also be considered as new generation energy. In order to integrate thin film solar cell into solar sail perfectly, the spectrum splitting technology using optical multilayer film is employed to divide the solar spectrum. The transmissivity of the designed optical film is calculated by a developed computer program. It shows that that the transmissivity is larger than 95% in the range 400-1000nm, and obviously decrease above 400 nm, and below 1000 nm. The result given in this work will provide a new way to realize a low area mass of the solar sail.

  10. 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.'

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Fabrication and performance of organic thin film solar cells using a painting method

    NASA Astrophysics Data System (ADS)

    Ochiai, S.; Ishihara, H.; Mizutani, T.; Kojima, K.

    2010-05-01

    As organic thin film solar cells fabricated by the active layer of organic materials are economical, lightweight, and flexible, as well as generating no CO2, and being easy to fabricate, they have attracted significant attention as green energy sources from a past decade to date. Therefore, their power conversion efficiency (PCE) has been investigated and studied worldwide. In organic thinfilm solar cells, the effect of the performance depends not only on the adopted active material but also relates to the molecular orientation on the electrode. Using a mixed solution of Poly(3-hexylthiophene) and PCBM, both of which were dissolved in a solvent, the organic thin films were fabricated using the paint and spray methods, while the morphology of the thin film was evaluated by an AFM image, UV/vis spectra, and so forth. Based on these data, an organic thin-film solar cell using both solution methods for the active layer was fabricated, and the performance evaluated and examined. For organic thin film solar cells fabricated using a spin-coating method, the open-circuit voltage (Voc) is 0.41V, the short circuit current density (Jsc) is 2.07mA/cm2, and the fill factor is 0.34, while the efficiency η of PCE become 0.29%. In the spray method, the short circuit current (Isc) is 2.5 mA/cm2, the open circuit voltage (Voc) is 0.45 V, the fill factor (FF) is 0.28, and the power conversion factor (PCE) 0.35%. The area of organic solar cells fabricated by spin coating and spray methods is 1 cm2 respectively. The organic solar cells are not thermally treated, and hence have high respective power conversion efficiencies.

  20. 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.

  1. ZnSe/ITO thin films: candidate for CdTe solar cell window layer

    NASA Astrophysics Data System (ADS)

    Khurram, A. A.; Imran, M.; Khan, Nawazish A.; Nasir Mehmood, M.

    2017-09-01

    The crystal structure, electrical and optical properties of ZnSe thin films deposited on an In2O3:Sn (ITO) substrate are evaluated for their suitability as the window layer of CdTe thin film solar cells. ZnSe thin films of 80, 90, and 100 nm thickness were deposited by a physical vapor deposition method on Indium tin oxide coated glass substrates. The lattice parameters are increased to 5.834 Å when the film thickness was 100 nm, which is close to that of CdS. The crystallite size is decreased with the increase of film thickness. The optical transmission analysis shows that the energy gap for the sample with the highest thickness has also increased and is very close to 2.7 eV. The photo decay is also studied as a function of ZnSe film thickness.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We report on fabrication of organic-inorganic perovskite thin films using a hybrid method consisting of pulsed laser deposition (PLD) of lead iodide and spin-coating of methylammonium iodide. Smooth and highly crystalline CH3NH3PbI3 thin films have been fabricated on silicon and glass coated substrates with fluorine doped tin oxide using this PLD-based hybrid method. Planar perovskite solar cells with an inverted structure have been successfully fabricated using the perovskite films. Because of its versatility, the PLD-based hybrid fabrication method not only provides an easy and precise control of the thickness of the perovskite thin films, but also offers a straightforward platform for studying the potential feasibility in using other metal halides and organic salts for formation of the organic-inorganic perovskite structure.

  3. Perovskite Solar Cell Using a Two-Dimensional Titania Nanosheet Thin Film as the Compact Layer

    SciTech Connect

    Li, Can; Li, Yahui; Xing, Yujin; Zhang, Zelin; Zhang, Xianfeng; Li, Zhen; Shi, Yantao; Ma, Tingli; Ma, Renzhi; Wang, Kunlin; Wei, Jinquan

    2015-07-22

    The compact layer plays an important role in conducting electrons and blocking holes in perovskite solar cells (PSCs). Here, we use a two-dimensional titania nanosheet (TNS) thin film as the compact layer in CH3NH3PbI3 PSCs. TNS thin films with thicknesses ranging from 8 to 75 nm were prepared by an electrophoretic deposition method from a dilute TNS/tetrabutylammonium hydroxide solution. The TNS thin films contact the fluorine-doped tin oxide grains perfectly. Our results show that a 8-nm-thick TNS film is sufficient for acting as the compact layer. Currently, the PSC with a TNS compact layer has a high efficiency of 10.7% and relatively low hysteresis behavior.

  4. Enhanced electrical characteristics of a-Si thin films by hydrogen passivation with Nd3+:YAG laser treatment in underwater for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Vidhya, Y. Esther Blesso; Vasa, Nilesh J.

    2017-08-01

    Post deposition underwater treatment with a nanosecond Nd3+:YAG laser is proposed and demonstrated for the passivation of electrical defects in 400-1000 nm-thick a-Si thin films needed for solar cells. The proposed pulsed laser beam-overlap technique also allows simultaneous annealing and texturing. Atomic hydrogen, oxygen, and hydroxyl radicals activated by the breakdown of water by laser heating passivate the dangling bonds in the crystal grains, improving the solar cell performance. The presence of hydrogen observed after water annealing using X-ray photo electron spectroscopy (XPS), Raman spectroscopy, and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) shows that the passivation improvement is caused by diffusion of atomic hydrogen. After underwater annealing, relative improvement in the life time of minority carriers was measured to be approximately 13% and the efficiency of n-aSi/p-cSi solar cells is found to be increased ( 2 to 3%) when compared to that in air.

  5. 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

  6. Impurity-doped ZnO Thin Films Prepared by Physical Deposition Methods Appropriate for Transparent Electrode Applications in Thin-film Solar Cells

    NASA Astrophysics Data System (ADS)

    Minami, Tadatsugu; Miyata, Toshihiro; Nomoto, Jun-ichi

    2012-04-01

    This paper describes the development of transparent conducting impurity-doped ZnO thin films that would be appropriate for applications as transparent electrodes in thin-film solar cells. Transparent conducting Al-, B- and Ga-doped ZnO (AZO, BZO and GZO) thin films were prepared in a thickness range from 500 to 2000 nm on glass substrates at 200°C using various physical deposition methods: BZO films with vacuum arc plasma evaporation, AZO and GZO films with different types of magnetron sputtering depositions (MSDs) and all films with pulsed laser deposition (PLD). The suitability and stability of the electrical properties and, in addition, the suitability of the light scattering characteristics and surface texture formation were investigated in the prepared thin films. In particular, the suitability and stability evaluation was focused on the use of AZO, BZO and GZO thin films prepared by doping each impurity at an appropriate content to attain the lowest resistivity. The higher Hall mobility obtained in impurity-doped ZnO thin films with a resistivity on the order of 10-4 Ωcm was related more to the content, i.e., the obtained carrier concentration, rather than the kind of impurity doped into the films. The stability of resistivity of the BZO thin films in long-term moisture-resistance tests (in air at 85% relative humidity and 85°C) was found to be lower than that of the AZO and GZO thin films. The surface texture formation was carried out by wet-chemical etching (in a 0.1% HCl solution at 25°C) conducted either before or after being heat-treated either with rapid thermal annealing (RTA) or without RTA. The suitability of the light scattering characteristics and the surface texture formation obtainable by wet-chemical etching (for use in transparent electrode applications) was considerably dependent on the deposition method used as well as whether the wet-chemical etching was conducted with or without RTA. A significant improvement of both transmittance and

  7. 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.

  8. Thin-film filament-based solar cells and modules

    NASA Astrophysics Data System (ADS)

    Tuttle, J. R.; Cole, E. D.; Berens, T. A.; Alleman, J.; Keane, J.

    1997-04-01

    This concept paper describes a patented, novel photovoltaic (PV) technology that is capable of achieving near-term commercialization and profitability based upon design features that maximize product performance while minimizing initial and future manufacturing costs. DayStar Technologies plans to exploit these features and introduce a product to the market based upon these differential positions. The technology combines the demonstrated performance and reliability of existing thin-film PV product with a cell and module geometry that cuts material usage by a factor of 5, and enhances performance and manufacturability relative to standard flat-plate designs. The target product introduction price is 1.50/Watt-peak (Wp). This is approximately one-half the cost of the presently available PV product. Additional features include: increased efficiency through low-level concentration, no scribe or grid loss, simple series interconnect, high voltage, light weight, high-throughput manufacturing, large area immediate demonstration, flexibility, modularity.

  9. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. 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

    Tandem solar cells (TSCs), which use two or more materials to absorb sunlight, have achieved power conversion efficiencies of >25% versus 11-20% for commercialized single junction solar cell modules. The key to widespread commercialization of TSCs is to develop the wide-band, top solar cell that is both cheap to fabricate and has a high open-circuit voltage (i.e. >1V). Previous work in TSCs has generally focused on using expensive processing techniques with slow growth rates resulting in costs that are two orders of magnitude too expensive to be used in conventional solar cell modules. The objective of the PLANT PV proposal was to investigate the feasibility of using Ag(In,Ga)Se2 (AIGS) as the wide-bandgap absorber in the top cell of a thin film tandem solar cell (TSC). Despite being studied by very few in the solar community, AIGS solar cells have achieved one of the highest open-circuit voltages within the chalcogenide material family with a Voc of 949 mV when grown with an expensive processing technique (i.e. Molecular Beam Epitaxy). PLANT PV's goal in Phase I of the DOE SBIR was to (1) develop the chemistry to grow AIGS thin films via solution processing techniques to reduce costs and (2) fabricate new device architectures with high open-circuit voltage to produce full tandem solar cells in Phase II. PLANT PV attempted to translate solution processing chemistries that were successful in producing >12% efficient Cu(In,Ga)Se2 solar cells by replacing copper compounds with silver. The main thrust of the research was to determine if it was possible to make high quality AIGS thin films using solution processing and to fully characterize the materials properties. PLANT PV developed several different types of silver compounds in an attempt to fabricate high quality thin films from solution. We found that silver compounds that were similar to the copper based system did not result in high quality thin films. PLANT PV was able to deposit AIGS thin

  11. 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

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

    DOE PAGES

    Yu, Yue; Zhao, Dewei; Grice, Corey R.; ...

    2016-09-16

    Here, 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, themore » good stoichiometry control of the MASnI3 thin films, and the effective passivation of the electron-blocking and hole-blocking layers. Finally, 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.« less

  13. 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

    2016-09-16

    Here, 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. Finally, 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.

  14. 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.

  15. Etching of a-Si:H thin films by hydrogen plasma: a view from in situ spectroscopic ellipsometry.

    PubMed

    Hadjadj, Aomar; Larbi, Fadila; Gilliot, Mickaël; Roca i Cabarrocas, Pere

    2014-08-28

    When atomic hydrogen interacts with hydrogenated amorphous silicon (a-Si:H), the induced modifications are of crucial importance during a-Si:H based devices manufacturing or processing. In the case of hydrogen plasma, the depth of the modified zone depends not only on the plasma processing parameters but also on the material. In this work, we exposed a-Si:H thin films to H2 plasma just after their deposition. In situ UV-visible spectroscopic ellipsometry measurements were performed to track the H-induced changes in the material. The competition between hydrogen insertion and silicon etching leads to first order kinetics in the time-evolution of the thickness of the H-modified zone. We analyzed the correlation between the steady state structural parameters of the H-modified layer and the main levers that control the plasma-surface interaction. In comparison with a simple doped layer, exposure of a-Si:H based junctions to the same plasma treatment leads to a thinner H-rich subsurface layer, suggesting a possible charged state of hydrogen diffusing.

  16. Processing and modeling issues for thin-film solar cell devices. Annual subcontract report, January 16, 1994--January 15, 1995

    SciTech Connect

    Birkmire, R.W.; Phillips, J.E.; Buchanan, W.A.; Hegedus, S.S.; McCandless, B.E.; Shafarman, W.N.

    1995-06-01

    This report describes results achieved during the second phase of a four year subcontract to develop and understand thin film solar cell technology related to a-Si and its alloys, CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2}, and CdTe. Accomplishments during this phase include, development of equations and reaction rates for the formation of CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} films by selenization, fabrication of a 15% efficient CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} cell, development of a reproducible, reliable Cu-diffused contact to CdTe, investigation of the role of CdTe-CdS interdiffusion on device operation, investigation of the substitution of HCl for CdCl{sub 2} in the post-deposition heat treatment of CdTe/CdS, demonstration of an improved reactor design for deposition of a-Si films, demonstration of improved process control in the fabrication of a ten set series of runs producing {approximately}8% efficient a-Si devices, demonstration of the utility of a simplified optical model for determining quantity and effect of current generation in each layer of a triple stacked a-Si cell, presentation of analytical and modeling procedures adapted to devices produced with each material system, presentation of baseline parameters for devices produced with each material system, and various investigations of the roles played by other layers in thin film devices including the Mo underlayer, CdS and ZnO in CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} devices, the CdS in CdTe devices, and the ZnO as window layer and as part of the back surface reflector in a-Si devices. In addition, collaborations with over ten research groups are briefly described. 73 refs., 54 figs., 34 tabs.

  17. Technical use of solar energy. Part 1. Thin films solar cells

    NASA Astrophysics Data System (ADS)

    Arndt, W.; Bauer, G. H.; Berger, H. U.; Bloss, W. H.; Hewig, G. H.; Pfisterer, F.; Schock, H. W.

    1983-12-01

    Due to the potentialities of Cu2-xS-CdS thin film solar cells, several companies installed production lines for this type of solar cell. Besides investigations for further enhancing efficiency and long-term stability, for gaining data of physical and electronical parameters, and for improving the theoretical knowledge of the cell, materials and technologies are investigated which look promising for large-scale industrial production. Solar cells with an area of 42 sq cm are realized, showing efficiencies of up to 8%; outdoor tests reveal that no system-inherent degradation mechanism exists when properly encapsulated cells are tested under realistic operation conditions. Large-area thin films of amorphous silicon with definite and reproducible properties are produced with two methods, both of which are well suited for the preparation: RF-sputtering in Ar/H2-mixtures and glow discharge in SiH4. Correlations exist between results of plasma diagnostics and analyses of the layers, allowing definite variations and an optimization of the production parameters. Various methods for the injection of different types of dopants into the plasma result in the implantation of electronically active dopants into the layers.

  18. New designs and characterization techniques for thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Pang, Yutong

    This thesis presents a fundamentally new thin-film photovoltaic design and develops several novel characterization techniques that improve the accuracy of thin-film solar cell computational models by improving the accuracy of the input data. We first demonstrate a novel organic photovoltaic (OPV) design, termed a "Slot OPV", in which the active layer is less than 50 nm; We apply the principles of slot waveguides to confine light within the active layer. According to our calculation, the guided-mode absorption for a 10nm thick active layer equal to the absorption of normal incidence on an OPV with a 100nm thick active layer. These results, together with the expected improvement in charge extraction for ultrathin layers, suggest that slot OPVs can be designed with greater power conversion efficiency than today's state-of-art OPV architectures if practical challenges, such as the efficient coupling of light into these modes, can be overcome. The charge collection probability, i.e. the probability that charges generated by absorption of a photon are successfully collected as current, is a critical feature for all kinds of solar cells. While the electron-beam-induced current (EBIC) method has been used in the past to successfully reconstruct the charge collection probability, this approach is destructive and requires time-consuming sample preparation. We demonstrate a new nondestructive optoelectronic method to reconstruct the charge collection probability by analyzing the internal quantum efficiency (IQE) data that are measured on copper indium gallium diselenide (CIGS) thin-film solar cells. We further improve the method with a parameter-independent regularization approach. Then we introduce the Self-Constrained Ill-Posed Inverse Problem (SCIIP) method, which improves the signal-to-noise of the solution by using the regularization method with system constraints and optimization via an evolutionary algorithm. For a thin-film solar cell optical model to be an accurate

  19. 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.

  20. 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%.

  1. 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%.

  2. Improving thin-film crystalline silicon solar cell efficiencies with photonic crystals.

    PubMed

    Bermel, Peter; Luo, Chiyan; Zeng, Lirong; Kimerling, Lionel C; Joannopoulos, John D

    2007-12-10

    Most photovoltaic (solar) cells are made from crystalline silicon (c-Si), which has an indirect band gap. This gives rise to weak absorption of one-third of usable solar photons. Therefore, improved light trapping schemes are needed, particularly for c-Si thin film solar cells. Here, a photonic crystal-based light-trapping approach is analyzed and compared to previous approaches. For a solar cell made of a 2 mum thin film of c-Si and a 6 bilayer distributed Bragg reflector (DBR) in the back, power generation can be enhanced by a relative amount of 24.0% by adding a 1D grating, 26.3% by replacing the DBR with a six-period triangular photonic crystal made of air holes in silicon, 31.3% by a DBR plus 2D grating, and 26.5% by replacing it with an eight-period inverse opal photonic crystal.

  3. Behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic modules under outdoor long term exposure

    PubMed Central

    Kichou, Sofiane; Silvestre, Santiago; Nofuentes, Gustavo; Torres-Ramírez, Miguel; Chouder, Aissa; Guasch, Daniel

    2016-01-01

    Four years׳ behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic (PV) modules installed in a relatively dry and sunny inland site with a Continental-Mediterranean climate (in the city of Jaén, Spain) are presented in this article. The shared data contributes to clarify how the Light Induced Degradation (LID) impacts the output power generated by the PV array, especially in the first days of exposure under outdoor conditions. Furthermore, a valuable methodology is provided in this data article permitting the assessment of the degradation rate and the stabilization period of the PV modules. Further discussions and interpretations concerning the data shared in this article can be found in the research paper “Characterization of degradation and evaluation of model parameters of amorphous silicon photovoltaic modules under outdoor long term exposure” (Kichou et al., 2016) [1]. PMID:26977439

  4. Behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic modules under outdoor long term exposure.

    PubMed

    Kichou, Sofiane; Silvestre, Santiago; Nofuentes, Gustavo; Torres-Ramírez, Miguel; Chouder, Aissa; Guasch, Daniel

    2016-06-01

    Four years׳ behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic (PV) modules installed in a relatively dry and sunny inland site with a Continental-Mediterranean climate (in the city of Jaén, Spain) are presented in this article. The shared data contributes to clarify how the Light Induced Degradation (LID) impacts the output power generated by the PV array, especially in the first days of exposure under outdoor conditions. Furthermore, a valuable methodology is provided in this data article permitting the assessment of the degradation rate and the stabilization period of the PV modules. Further discussions and interpretations concerning the data shared in this article can be found in the research paper "Characterization of degradation and evaluation of model parameters of amorphous silicon photovoltaic modules under outdoor long term exposure" (Kichou et al., 2016) [1].

  5. 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

  6. 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)

  7. 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.

  8. Transparent solar antenna of 28 GHz using transparent conductive oxides (TCO) thin film

    NASA Astrophysics Data System (ADS)

    Ali, N. I. Mohd; Misran, N.; Mansor, M. F.; Jamlos, M. F.

    2017-05-01

    This paper presents the analysis of 28GHz solar patch antenna using the variations of transparent conductive oxides (TCO) thin film as the radiating patch. Solar antenna is basically combining the function of antenna and solar cell into one device and helps to maximize the usage of surface area. The main problem of the existing solar antenna is the radiating patch which made of nontransparent material, such as copper, shadowing the solar cell and degrades the total solar efficiency. Hence, by using the transparent conductive oxides (TCO) thin film as the radiating patch, this problem can be tackled. The TCO thin film used is varied to ITO, FTO, AgHT-4, and AgHT-8 along with glass as substrate. The simulation of the antenna executed by using Computer Simulation Technology (CST) Microwave Studio software demonstrated at 28 GHz operating frequency for 5G band applications. The performance of the transparent antennas is compared with each other and also with the nontransparent patch antenna that using Rogers RT5880 as substrate, operating at the same resonance frequency and then, the material that gives the best performance is identified.

  9. Non-vacuum deposition methods for thin film solar cell: Review

    NASA Astrophysics Data System (ADS)

    Yang, Ruisheng; Mazalan, Elham; Chaudhary, Kashif Tufail; Haider, Zuhaib; Ali, Jalil

    2017-03-01

    Solar power is a promising abundant, pollution free, inexhaustible and clean source of energy. Development of cost-effective solar system with high conversion efficiency is the key challenge in field of solar panel manufacturing industry. Different non-vacuum deposition methods have been developed to reduce the cost of solar panel system along with high conversion efficiency. In this paper, a review is presented with major focus on three non-vacuum deposition methods, as spin coating, dip coating and spray coating. Each mentioned deposition technique is discussed in details along with role of different deposition parameters on the characteristics of grown solar thin films.

  10. 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.

  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. 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).

  13. 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.

  14. 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.

  15. 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.

  16. Scattering effect of the high-index dielectric nanospheres for high performance hydrogenated amorphous silicon thin-film solar cells

    PubMed Central

    Yang, Zhenhai; Gao, Pingqi; Zhang, Cheng; Li, Xiaofeng; Ye, Jichun

    2016-01-01

    Dielectric nanosphere arrays are considered as promising light-trapping designs with the capability of transforming the freely propagated sunlight into guided modes. This kinds of designs are especially beneficial to the ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells due to the advantages of using lossless material and easily scalable assembly. In this paper, we demonstrate numerically that the front-sided integration of high-index subwavelength titanium dioxide (TiO2) nanosphere arrays can significantly enhance the light absorption in 100 nm-thick a-Si:H thin films and thus the power conversion efficiencies (PCEs) of related solar cells. The main reason behind is firmly attributed to the strong scattering effect excited by TiO2 nanospheres in the whole waveband, which contributes to coupling the light into a-Si:H layer via two typical ways: 1) in the short-waveband, the forward scattering of TiO2 nanospheres excite the Mie resonance, which focuses the light into the surface of the a-Si:H layer and thus provides a leaky channel; 2) in the long-waveband, the transverse waveguided modes caused by powerful scattering effectively couple the light into almost the whole active layer. Moreover, the finite-element simulations demonstrate that photocurrent density (Jph) can be up to 15.01 mA/cm2, which is 48.76% higher than that of flat system. PMID:27455911

  17. Scattering effect of the high-index dielectric nanospheres for high performance hydrogenated amorphous silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Yang, Zhenhai; Gao, Pingqi; Zhang, Cheng; Li, Xiaofeng; Ye, Jichun

    2016-07-01

    Dielectric nanosphere arrays are considered as promising light-trapping designs with the capability of transforming the freely propagated sunlight into guided modes. This kinds of designs are especially beneficial to the ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells due to the advantages of using lossless material and easily scalable assembly. In this paper, we demonstrate numerically that the front-sided integration of high-index subwavelength titanium dioxide (TiO2) nanosphere arrays can significantly enhance the light absorption in 100 nm-thick a-Si:H thin films and thus the power conversion efficiencies (PCEs) of related solar cells. The main reason behind is firmly attributed to the strong scattering effect excited by TiO2 nanospheres in the whole waveband, which contributes to coupling the light into a-Si:H layer via two typical ways: 1) in the short-waveband, the forward scattering of TiO2 nanospheres excite the Mie resonance, which focuses the light into the surface of the a-Si:H layer and thus provides a leaky channel; 2) in the long-waveband, the transverse waveguided modes caused by powerful scattering effectively couple the light into almost the whole active layer. Moreover, the finite-element simulations demonstrate that photocurrent density (Jph) can be up to 15.01 mA/cm2, which is 48.76% higher than that of flat system.

  18. Scattering effect of the high-index dielectric nanospheres for high performance hydrogenated amorphous silicon thin-film solar cells.

    PubMed

    Yang, Zhenhai; Gao, Pingqi; Zhang, Cheng; Li, Xiaofeng; Ye, Jichun

    2016-07-26

    Dielectric nanosphere arrays are considered as promising light-trapping designs with the capability of transforming the freely propagated sunlight into guided modes. This kinds of designs are especially beneficial to the ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells due to the advantages of using lossless material and easily scalable assembly. In this paper, we demonstrate numerically that the front-sided integration of high-index subwavelength titanium dioxide (TiO2) nanosphere arrays can significantly enhance the light absorption in 100 nm-thick a-Si:H thin films and thus the power conversion efficiencies (PCEs) of related solar cells. The main reason behind is firmly attributed to the strong scattering effect excited by TiO2 nanospheres in the whole waveband, which contributes to coupling the light into a-Si:H layer via two typical ways: 1) in the short-waveband, the forward scattering of TiO2 nanospheres excite the Mie resonance, which focuses the light into the surface of the a-Si:H layer and thus provides a leaky channel; 2) in the long-waveband, the transverse waveguided modes caused by powerful scattering effectively couple the light into almost the whole active layer. Moreover, the finite-element simulations demonstrate that photocurrent density (Jph) can be up to 15.01 mA/cm(2), which is 48.76% higher than that of flat system.

  19. 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%.

  20. Requirements for Thin Film Solar Arrays and the Development Status of a New Solar Cell Blanket Concept

    NASA Astrophysics Data System (ADS)

    Zwanenburg, R.; Kroon, M.

    2005-05-01

    A novel blanket concept for thin film solar cells has been developed by Dutch Space. This blanket design, called the "Matrix" (patent pending), is formed by just connecting the thin film solar cells to each other at their corner points with plastic connection strips. The typical mass is only 240 g/m2 with CIGS solar cells made on 25 μm titanium foil. Interconnects are established by a pressure contact between the solar cells. Blanket samples of 48 connected solar cells (partly with live prototype solar cells) have been made and will be tested soon for thermal cycling and acoustic noise environments. The Matrix blanket design appears to be a very attractive solution and can be used on solar array level for solar cell blankets tensioned in panel frames and for large fold-out blanket arrays using masts.

  1. Relationships between Lead Halide Perovskite Thin-Film Fabrication, Morphology, and Performance in Solar Cells.

    PubMed

    Sharenko, Alexander; Toney, Michael F

    2016-01-20

    Solution-processed lead halide perovskite thin-film solar cells have achieved power conversion efficiencies comparable to those obtained with several commercial photovoltaic technologies in a remarkably short period of time. This rapid rise in device efficiency is largely the result of the development of fabrication protocols capable of producing continuous, smooth perovskite films with micrometer-sized grains. Further developments in film fabrication and morphological control are necessary, however, in order for perovskite solar cells to reliably and reproducibly approach their thermodynamic efficiency limit. This Perspective discusses the fabrication of lead halide perovskite thin films, while highlighting the processing-property-performance relationships that have emerged from the literature, and from this knowledge, suggests future research directions.

  2. 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.

  3. 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.

  4. 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.

  5. BiSI Micro-Rod Thin Films: Efficient Solar Absorber Electrodes?

    PubMed

    Hahn, Nathan T; Self, Jeffrey L; Mullins, C Buddie

    2012-06-07

    The development of improved solar energy conversion materials is critical to the growth of a sustainable energy infrastructure in the coming years. We report the deposition of polycrystalline BiSI thin films exhibiting promising photoelectrochemical properties on both metal foils and fluorine-doped tin-oxide-coated glass slides using a single-source chemical spray pyrolysis technique. Their strong light absorption in the visible range and well-crystallized layered structure give rise to their excellent photoelectrochemical performance through improved electron-hole generation and separation. The structure and surface composition of the films are dependent on deposition temperature, resulting in dramatic differences in performance over the temperature range studied. These results reveal the potential of n-BiSI as an alternative thin film solar energy conversion material and may stimulate further investigation into V-VI-VII compounds for these applications.

  6. Plasmonic Light Trapping in Thin-Film Solar Cells: Impact of Modeling on Performance Prediction

    PubMed Central

    Micco, Alberto; Pisco, Marco; Ricciardi, Armando; Mercaldo, Lucia V.; Usatii, Iurie; La Ferrara, Vera; Delli Veneri, Paola; Cutolo, Antonello; Cusano, Andrea

    2015-01-01

    We present a comparative study on numerical models used to predict the absorption enhancement in thin-film solar cells due to the presence of structured back-reflectors exciting, at specific wavelengths, hybrid plasmonic-photonic resonances. To evaluate the effectiveness of the analyzed models, they have been applied in a case study: starting from a U-shaped textured glass thin-film, µc-Si:H solar cells have been successfully fabricated. The fabricated cells, with different intrinsic layer thicknesses, have been morphologically, optically and electrically characterized. The experimental results have been successively compared with the numerical predictions. We have found that, in contrast to basic models based on the underlying schematics of the cell, numerical models taking into account the real morphology of the fabricated device, are able to effectively predict the cells performances in terms of both optical absorption and short-circuit current values.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Persistent photoconductivity studies in a-Si:H/nc-Si:H thin film superlattices

    NASA Astrophysics Data System (ADS)

    Yadav, Asha; Agarwal, Pratima

    2015-09-01

    The electronic properties of undoped a-Si:H/nc-Si:H superlattice structures have been investigated by photoconductivity measurements. Multilayer structures having alternate layers of a-Si:H and nc-Si:H were deposited on corning 1737 glass substrate by Hot wire chemical vapor deposition technique, keeping the total thickness of films constant at 700 nm. Dark and photo conductivity along with persistent photoconductivity (PPC) are measured in coplanar geometry using Ag paste as electrodes. Quite interestingly room temperature PPC has been observed in these undoped a-Si:H/nc-Si:H superlattice structures. PPC decay time constant, its dependence on exposure time, electric field, number of periods and annealing temperature have been studied in detail. The origin of PPC is understood in terms of competition between carriers transport in the lateral direction due to external field and along the depth due to band bending at a-Si:H/nc-Si:H interfaces. Carriers trapped in the interfaces states or the separation of carriers due to band bending are likely to be responsible for observed PPC.

  15. 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.

  16. 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.

  17. Design and Optimization of Copper Indium Gallium Selenide Thin Film Solar Cells

    DTIC Science & Technology

    2015-09-01

    system is rated at providing 300 W of continuous power that is generated from a set of solar panels rated at 1.6 kW and includes a set of batteries that...region=8 conmob # SOLAR LIGHT (AM 1.5) beam num=1 x.origin=0.5 y.origin=-2 angle =90 am1.5 wavel.start=0.285 wavel.end=1.655 wavel.num=137...OPTIMIZATION OF COPPER INDIUM GALLIUM SELENIDE THIN FILM SOLAR CELLS by Daniel B. Katzman September 2015 Thesis Advisor: Sherif Michael Second

  18. Approaching the Lambertian limit in randomly textured thin-film solar cells.

    PubMed

    Fahr, Stephan; Kirchartz, Thomas; Rockstuhl, Carsten; Lederer, Falk

    2011-07-04

    The Lambertian limit for solar cells is a benchmark for evaluating their efficiency. It has been shown that the performance of either extremely thick or extremely thin solar cells can be driven close to this limit by using an appropriate photon management. Here we show that this is likewise possible for realistic, practically relevant thin-film solar cells based on amorphous silicon. Most importantly, we achieve this goal by relying on random textures already incorporated into state-of-the-art superstrates; with the only subtlety that their topology has to be downscaled to typical feature sizes of about 100 nm.

  19. 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.

  20. 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.

  1. Use of sol-gel thin films in solar energy applications

    SciTech Connect

    Pettit, R.B.; Brinker, C.J.

    1985-01-01

    The sol-gel process uses metal alkoxides of network forming cations, such as Si, B, or Al, in alcohol/water solutions to form glass-like, polymeric networks in liquid solution. Thin films are formed by depositing the solution on a substrate by spinning, dipping or spraying. When the film is then heated to moderate temperatures (400 to 500/sup 0/C), dense glass films or stable porous films are obtained. The use of sol-gel thin films in four solar energy materials applications is discussed. Encapsulation of black chrome solar selective coatings improved the high temperature thermal stability by a factor of 2.7. Formation of porous, antireflection coatings on glass envelopes used in solar thermal collectors increased the solar transmittance of the glass from 0.91 to greater than 0.96. Double-layer, antireflection coatings of SiO/sub 2/ and TiO/sub 2/ on silicon solar cells reduced the solar reflectance of the cells from 0.36 to 0.04 and thereby improved cell efficiencies by 50%. Protective coatings applied to silvered stainless steel substrates were used to form structural solar mirrors. Solar averaged specular reflectance values of 0.90 to 0.91 were obtained.

  2. 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)

  3. Advanced light-trapping effect of thin-film solar cell with dual photonic crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Anjun; Guo, Zhongyi; Tao, Yifei; Wang, Wei; Mao, Xiaoqin; Fan, Guanghua; Zhou, Keya; Qu, Shiliang

    2015-05-01

    A thin-film solar cell with dual photonic crystals has been proposed, which shows an advanced light-trapping effect and superior performance in ultimate conversion efficiency (UCE). The shapes of nanocones have been optimized and discussed in detail by self-definition. The optimized shape of nanocone arrays (NCs) is a parabolic shape with a nearly linearly graded refractive index (GRI) profile from the air to Si, and the corresponding UCE is 30.3% for the NCs with a period of 300 nm and a thickness of only 2 μm. The top NCs and bottom NCs of the thin film have been simulated respectively to investigate their optimized shapes, and their separate contributions to the light harvest have also been discussed fully. The height of the top NCs and bottom NCs will also influence the performances of the thin-film solar cell greatly, and the result indicates that the unconformal NCs have better light-trapping ability with an optimal UCE of 32.3% than the conformal NCs with an optimal UCE of 30.3%.

  4. Cross-sectional electrostatic force microscopy of thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Ballif, C.; Moutinho, H. R.; Al-Jassim, M. M.

    2001-01-01

    In a recent work, we showed that atomic force microscopy (AFM) is a powerful technique to image cross sections of polycrystalline thin films. In this work, we apply a modification of AFM, namely, electrostatic force microscopy (EFM), to investigate the electronic properties of cleaved II-VI and multijunction thin-film solar cells. We cleave the devices in such a way that they are still working with their nominal photovoltaic efficiencies and can be polarized for the measurements. This allows us to differentiate between surface effects (work function and surface band bending) and bulk device properties. In the case of polycrystalline CdTe/CdS/SnO2/glass solar cells, we find a drop of the EFM signal in the area of the CdTe/CdS interface (±50 nm). This drop varies in amplitude and sign according to the applied external bias and is compatible with an n-CdS/p-CdTe heterojunction model, thereby invalidating the possibility of a deeply buried n-p CdTe homojunction. In the case of a triple-junction GaInP/GaAs/Ge device, we observe a variation of the EFM signal linked to both the material work-function differences and to the voltage bias applied to the cell. We attempt a qualitative explanation of the results and discuss the implications and difficulties of the EFM technique for the study of such thin-film devices.

  5. Advanced light-trapping effect of thin-film solar cell with dual photonic crystals.

    PubMed

    Zhang, Anjun; Guo, Zhongyi; Tao, Yifei; Wang, Wei; Mao, Xiaoqin; Fan, Guanghua; Zhou, Keya; Qu, Shiliang

    2015-01-01

    A thin-film solar cell with dual photonic crystals has been proposed, which shows an advanced light-trapping effect and superior performance in ultimate conversion efficiency (UCE). The shapes of nanocones have been optimized and discussed in detail by self-definition. The optimized shape of nanocone arrays (NCs) is a parabolic shape with a nearly linearly graded refractive index (GRI) profile from the air to Si, and the corresponding UCE is 30.3% for the NCs with a period of 300 nm and a thickness of only 2 μm. The top NCs and bottom NCs of the thin film have been simulated respectively to investigate their optimized shapes, and their separate contributions to the light harvest have also been discussed fully. The height of the top NCs and bottom NCs will also influence the performances of the thin-film solar cell greatly, and the result indicates that the unconformal NCs have better light-trapping ability with an optimal UCE of 32.3% than the conformal NCs with an optimal UCE of 30.3%.

  6. 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.

  7. 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.

  8. Solvent Effect on the Formation of Photoactive Thin Films for the Polymeric Solar Cells

    NASA Astrophysics Data System (ADS)

    Yusli, Mohd Nizam; Sulaiman, Khaulah

    2009-07-01

    This work investigates the influence of the solvent used on the morphology of polymer photoactive layer for solar cells. The photoactive layer consists a mixture of poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), to produce P3HT:PCBM (1:1 ratio) blend thin films, deposited by spin-coating technique of the materials solution. Two types of the solvents used namely; 100% dichlorobenzene (DCB) and 50%:50% cosolvent of DCB and chloroform. The morphological characterizations of P3HT:PCBM blend thin films have been carried out by UV-Visible absorption spectroscopy, X-ray diffraction (XRD) spectroscopy, and Atomic Force Microscopy (AFM). The results reveal that the mixtures of solvent give a better solubility than the pure single solvent. And thus, the choice of solvent used during the fabrication process can significantly affect the optical and morphological properties of the films.

  9. Identification of critical stacking faults in thin-film CdTe solar cells

    SciTech Connect

    Yoo, Su-Hyun; Walsh, Aron; Butler, Keith T.; Soon, Aloysius; Abbas, Ali; Walls, John M.

    2014-08-11

    Cadmium telluride (CdTe) is a p-type semiconductor used in thin-film solar cells. To achieve high light-to-electricity conversion, annealing in the presence of CdCl{sub 2} is essential, but the underlying mechanism is still under debate. Recent evidence suggests that a reduction in the high density of stacking faults in the CdTe grains is a key process that occurs during the chemical treatment. A range of stacking faults, including intrinsic, extrinsic, and twin boundary, are computationally investigated to identify the extended defects that limit performance. The low-energy faults are found to be electrically benign, while a number of higher energy faults, consistent with atomic-resolution micrographs, are predicted to be hole traps with fluctuations in the local electrostatic potential. It is expected that stacking faults will also be important for other thin-film photovoltaic technologies.

  10. Theoretical study of alternative thin film solar cells. Final report

    SciTech Connect

    Pauwels, H.

    1984-01-01

    The investigation covers two main subjects:- (1) energy barriers and interface effects on the efficiency of heterojunction solar cells, and (2) a literature search on materials that would perform best in optimum structures. Work reported on point (1) includes the effect of tunnelling, the generation and recombination of charge carriers, as well as on the current-voltage characteristics of solar cells. After detailed studies on the best performing materials, subjects for future work were suggested, such as research into metal-semi-conductor junctions. Appendices give relevant extracts from various publications.

  11. Development of High Efficient Organic Thin-film Solar Cells

    NASA Astrophysics Data System (ADS)

    Hiramoto, Masahiro

    Fundamental principles and p-i-n junction concept of organic solar cells are described. Methods for improvement of conversion efficiency such as nanostructure design of co-deposited i-layer and high-purification of organic semiconductors are explained. Conversion efficiency exceeding 5% was observed. Cell operation for 1000 hours (42 days) was successfully accomplished.

  12. High efficiency thin-film GaAs solar cells

    SciTech Connect

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

    1981-01-01

    This research is directed toward demonstrating the feasibility of producing high-efficiency GaAs solar cells with high power-to-weight ratio by organo-metallic chemical vapor deposition (OM-CVD) growth of thin epi-layers on suitable substrates. 4 refs.

  13. 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.

  14. 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.

  15. Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays.

    PubMed

    Contreras, Javier; Tornero, Josep; Ferreira, Isabel; Martins, Rodrigo; Gomes, Luis; Fortunato, Elvira

    2015-11-30

    A MATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array.

  16. Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays

    PubMed Central

    Contreras, Javier; Tornero, Josep; Ferreira, Isabel; Martins, Rodrigo; Gomes, Luis; Fortunato, Elvira

    2015-01-01

    A MATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array. PMID:26633403

  17. Patterning of Transparent Conducting Oxide Thin Films by Wet Etching for a-Si:H TFT-LCDs

    SciTech Connect

    Lan, J. H.; Kanicki, J.; Catalano, A.; Keane, J.; Den Boer, W.; Gu, T.

    1996-12-01

    The patterning characteristics of the indium tin oxide (ITO) thin films having different microstructures were investigated. Several etching solutions (HCl, HBr, and their mixtures with HNO3) were used in this study. We have found that ITO films containing a larger volume fraction of the amorphous phase show higher etch rates than those containing a larger volume fraction of the crystalline phase. Also, the crystalline ITO fims have shown a very good uniformity in patterning, and following the etching no ITO residue (unetched ITO) formation has been observed. In contrast, ITO residues were found after the etching of the films containing both amorphous and crystalline phases. We have also developed a process for the fabrication of the ITO with a tapered edge profile. The taper angle can be controlled by varying the ratio of HNO3 to the HCl in the etching solutions. Finally, ITO films have been found to be chemically unstable in a hydrogen containing plasma environment. On the contrary, aluminum doped zinc oxide (AZO) films, having an optical transmittance and electrical resisitivity comparable to ITO films, are very stable in the same hydrogen containing plasma environment. In addition, a high etch rate, no etching residue formation, and a uniform etching have been found for the AZO films, which make them suitable for a-Si:H TFT-LCD applications.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.

    PubMed

    Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

    2014-10-01

    A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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

  5. Doping-free silicon thin film solar cells using a vanadium pentoxide window layer and a LiF/Al back electrode

    NASA Astrophysics Data System (ADS)

    Jung, Hyung Hwan; Kwon, Jung-Dae; Lee, Sunghun; Su Kim, Chang; Nam, Kee-Seok; Jeong, Yongsoo; Chung, Kwun-Bum; Yoon Ryu, Seung; Ocak, Tülay; Eray, Aynur; Kim, Dong-Ho; Park, Sung-Gyu

    2013-08-01

    This work describes the preparation of a doped layer-free hydrogenated amorphous silicon (a-Si:H) thin film solar cell consisting of a vanadium pentoxide (V2O5-x) window layer, an intrinsic a-Si:H absorber layer, and a lithium fluoride (LiF)/aluminum (Al) back electrode. The large difference between the work functions of the V2O5-x layer and the LiF/Al electrode permitted photogenerated carriers in the i-a-Si:H absorber layer to be effectively separated and collected. The effects of the V2O5-x layer thickness and the oxidation states on the photovoltaic performance were investigated in detail. X-ray photoelectron spectroscopy analysis confirmed that the major species of the sputtered V2O5-x thin films were V5+ and V4+. Optimization of the V2O5-x window layer yielded a power conversion efficiency of 7.04%, which was comparable to the power conversion efficiency of a typical a-Si:H solar cell (7.09%).

  6. 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.

  7. 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.

  8. Inserted layer of AZO thin film with high work function between transparent conductive oxide and p-layer and its solar cell application.

    PubMed

    Park, Hyeongsik; Lee, Jaehyeong; Lee, Youn-Jung; Kim, Heewon; Jung, Junhee; Hussain, S Qamar; Park, Jinjoo; Shin, Chonghoon; Kim, Sunbo; Ahn, Shihyun; Yil, Junsin

    2013-10-01

    We report aluminum doped zinc oxide (AZO) films with high work function as an insertion layer between transparent conducting oxides (TCO) and hydrogenated amorphous silicon carbide (a-SiC:H) layer to improve open circuit voltage (V(oc)) and fill factor (FF) for thin film solar cells. Amorphous silicon (a-Si:H) solar cells exhibit poor fill factors due to a Schottky barrier at the interface between a-SiC:H window and TCO. The interface engineering is carried out by inserting an AZO layer with high work function (4.95 eV at O2 = 2 sccm). As a result, V(oc) and FF improved significantly. FF as high as 63.35% is obtained.

  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. 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.

  11. 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.

  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. 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.

  14. Effects of Plasmonic Metal Core -Dielectric Shell Nanoparticles on the Broadband Light Absorption Enhancement in Thin Film Solar Cells.

    PubMed

    Yu, Peng; Yao, Yisen; Wu, Jiang; Niu, Xiaobin; Rogach, Andrey L; Wang, Zhiming

    2017-08-09

    To guide the design of plasmonic solar cells, theoretical investigation of core (metal)-shell (dielectric) nanoparticles for light absorption enhancement in thin film Si solar cells is performed. In contrast to the reported simulations and experimental results that rear-located surface plasmon on bare metallic nanoparticles is preferred, the core-shell nanoparticles demonstrate better performance when surface plasmon is located in front of a solar cell. This has been attributed to the enhanced forward scattering with vanishing backward scattering preserved over a wide spectral range in core-shell nanoparticles. This work provides a concept to achieve enhanced forward scattering with weakened backward scattering in plasmonic thin film solar cells.

  15. 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.

  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. 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.

  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. Carrier collection losses in interface passivated amorphous silicon thin-film solar cells

    SciTech Connect

    Neumüller, A. Sergeev, O.; Vehse, M.; Agert, C.; Bereznev, S.; Volobujeva, O.; Ewert, M.; Falta, J.

    2016-07-25

    In silicon thin-film solar cells the interface between the i- and p-layer is the most critical. In the case of back diffusion of photogenerated minority carriers to the i/p-interface, recombination occurs mainly on the defect states at the interface. To suppress this effect and to reduce recombination losses, hydrogen plasma treatment (HPT) is usually applied. As an alternative to using state of the art HPT we apply an argon plasma treatment (APT) before the p-layer deposition in n-i-p solar cells. To study the effect of APT, several investigations were applied to compare the results with HPT and no plasma treatment at the interface. Carrier collection losses in resulting solar cells were examined with spectral response measurements with and without bias voltage. To investigate single layers, surface photovoltage and X-ray photoelectron spectroscopy (XPS) measurements were conducted. The results with APT at the i/p-interface show a beneficial contribution to the carrier collection compared with HPT and no plasma treatment. Therefore, it can be concluded that APT reduces the recombination centers at the interface. Further, we demonstrate that carrier collection losses of thin-film solar cells are significantly lower with APT.

  20. Carrier collection losses in interface passivated amorphous silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Neumüller, A.; Bereznev, S.; Ewert, M.; Volobujeva, O.; Sergeev, O.; Falta, J.; Vehse, M.; Agert, C.

    2016-07-01

    In silicon thin-film solar cells the interface between the i- and p-layer is the most critical. In the case of back diffusion of photogenerated minority carriers to the i/p-interface, recombination occurs mainly on the defect states at the interface. To suppress this effect and to reduce recombination losses, hydrogen plasma treatment (HPT) is usually applied. As an alternative to using state of the art HPT we apply an argon plasma treatment (APT) before the p-layer deposition in n-i-p solar cells. To study the effect of APT, several investigations were applied to compare the results with HPT and no plasma treatment at the interface. Carrier collection losses in resulting solar cells were examined with spectral response measurements with and without bias voltage. To investigate single layers, surface photovoltage and X-ray photoelectron spectroscopy (XPS) measurements were conducted. The results with APT at the i/p-interface show a beneficial contribution to the carrier collection compared with HPT and no plasma treatment. Therefore, it can be concluded that APT reduces the recombination centers at the interface. Further, we demonstrate that carrier collection losses of thin-film solar cells are significantly lower with APT.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Non-Uniformities in Thin-Film Cadmium Telluride Solar Cells Using Electroluminescence and Photoluminescence: Preprint

    SciTech Connect

    Zaunbrecher, K.; Johnston, S.; Yan, F.; Sites, J.

    2011-07-01

    It is the purpose of this research to develop specific imaging techniques that have the potential to be fast, in-line tools for quality control in thin-film CdTe solar cells. Electroluminescence (EL) and photoluminescence (PL) are two techniques that are currently under investigation on CdTe small area devices made at Colorado State University. It is our hope to significantly advance the understanding of EL and PL measurements as applied to CdTe. Qualitative analysis of defects and non-uniformities is underway on CdTe using EL, PL, and other imaging techniques.

  9. Chemical Etching of Zinc Oxide for Thin-Film Silicon Solar Cells

    PubMed Central

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

    2012-01-01

    Abstract 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. PMID:22162035

  10. Surpassing the classical light-trapping limit in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Munday, Jeremy; Callahan, Dennis; Atwater, Harry

    2011-03-01

    We describe a methodology for designing thin film solar cells that have light-trapping intensity and absorption enhancements that exceed the classical, ergodic light-trapping limit. From thermodynamic arguments, Yablonovitch and Cody determined the maximum absorption enhancement in the ray optics limit for a bulk material to be 4n2 , where n is the index of refraction of the absorbing layer. Stuart and Hall expanded this approach to study a simple waveguide structure; however, for the waveguide structures they considered, the maximum absorption enhancement was <4n^ 2 . Usingacombinationofanalyticalandnumericalmethods , wedescribewhythesestructuresdonotsurpasstheergodiclimitandshowhowtodesignstructuresthatcan . Wepresenthereaphysicalinterpretationintermsofthewaveguidedispersionrelationsandopticaldensityofstates . Wefurtherdescribethenecessarycriteriaforsurpassingtheclassicallimitandprovideexamplesofwaveguidestructureswithabsorptionenhancementsinexcessof 4n2 .

  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. 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.

  13. 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 °.

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Fabrication of Source/Drain Electrodes for a-Si:H Thin-Film Transistors Using a Single Cu Alloy Target

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Lee, C. Y.; Nam, H. S.; Lee, J. G.; Yang, H. J.; Ho, W. J.; Jeong, J. Y.; Koo, D. H.

    2011-11-01

    A Cu alloy/Cu alloy oxide bilayer structure was formed on an n +-a-Si:H substrate using a single Cu alloy target. It was employed for the source/drain electrodes in the fabrication of a-Si:H thin-film transistors with good electrical performance, high thermal stability, and good adhesion. Transmission electron microscopy and electron energy-loss spectroscopy analyses revealed that the initial sputtering of the Cu alloy in O2/Ar allowed for preferential oxidation of Si and the formation of a SiO x /Cu-supersaturated a-Si:H bilayer at the copper oxide-a-Si:H interface. This bilayer turned into an SiO x /Cu3Si bilayer after annealing at 300°C. It provided a stable contact structure with low contact resistance.

  20. 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

  1. Optimal design of one-dimensional photonic crystal back reflectors for thin-film silicon solar cells

    SciTech Connect

    Chen, Peizhuan; Hou, Guofu Zhang, Jianjun Zhang, Xiaodan; Zhao, Ying

    2014-08-14

    For thin-film silicon solar cells (TFSC), a one-dimensional photonic crystal (1D PC) is a good back reflector (BR) because it increases the total internal reflection at the back surface. We used the plane-wave expansion method and the finite difference time domain (FDTD) algorithm to simulate and analyze the photonic bandgap (PBG), the reflection and the absorption properties of a 1D PC and to further explore the optimal 1D PC design for use in hydrogenated amorphous silicon (a-Si:H) solar cells. With identified refractive index contrast and period thickness, we found that the PBG and the reflection of a 1D PC are strongly influenced by the contrast in bilayer thickness. Additionally, light coupled to the top three periods of the 1D PC and was absorbed if one of the bilayers was absorptive. By decreasing the thickness contrast of the absorptive layer relative to the non-absorptive layer, an average reflectivity of 96.7% was achieved for a 1D PC alternatively stacked with a-Si:H and SiO{sub 2} in five periods. This reflectivity was superior to a distributed Bragg reflector (DBR) structure with 93.5% and an Ag film with 93.4%. n-i-p a-Si:H solar cells with an optimal 1D PC-based BR offer a higher short-circuit current density than those with a DBR-based BR or an AZO/Ag-based BR. These results provide new design rules for photonic structures in TFSC.

  2. Shrinking and growing: grain boundary density reduction for efficient polysilicon thin-film solar cells.

    PubMed

    Kim, Dong Rip; Lee, Chi Hwan; Weisse, Jeffrey M; Cho, In Sun; Zheng, Xiaolin

    2012-12-12

    Polycrystalline Si (poly-Si) thin-film, due to its low Si consumption, low substrate cost, and good stability, is an attractive candidate for cost-effective solar cells, but the as-deposited poly-Si typically has a columnar structure with grain boundaries in between, severely limiting the efficiency of the poly-Si. Here, we report a micropillar poly-Si solar cell that utilizes the columnar structure of the as-deposited poly-Si grains. We first formed submicrometer diameter poly-Si pillars, smaller than the initial grain sizes, and used these pillars as the seeds for the subsequent epitaxial growth of Si, which effectively reduces grain boundary density in the final poly-Si crystal. In addition, the vertically aligned micropillar arrays form radial p-n junctions that further mitigate the grain boundary recombination losses by improving the light absorption and charge-carrier collection efficiencies. Consequently, the maximum efficiency of micropillar poly-Si thin-film solar cells is 6.4%, that is, ∼1.5 times higher than that of the planar cells.

  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. 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.

  5. 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.

  6. 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.

  7. Multi-Material Front Contact for 19% Thin Film Solar Cells.

    PubMed

    van Deelen, Joop; Tezsevin, Yasemin; Barink, Marco

    2016-02-06

    The trade-off between transmittance and conductivity of the front contact material poses a bottleneck for thin film solar panels. Normally, the front contact material is a metal oxide and the optimal cell configuration and panel efficiency were determined for various band gap materials, representing Cu(In,Ga)Se₂ (CIGS), CdTe and high band gap perovskites. Supplementing the metal oxide with a metallic copper grid improves the performance of the front contact and aims to increase the efficiency. Various front contact designs with and without a metallic finger grid were calculated with a variation of the transparent conductive oxide (TCO) sheet resistance, scribing area, cell length, and finger dimensions. In addition, the contact resistance and illumination power were also assessed and the optimal thin film solar panel design was determined. Adding a metallic finger grid on a TCO gives a higher solar cell efficiency and this also enables longer cell lengths. However, contact resistance between the metal and the TCO material can reduce the efficiency benefit somewhat.

  8. 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

  9. 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.

  10. 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.

  11. Development of Earth-Abundant and Non-Toxic Thin-Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Park, Helen Hejin

    Although solar energy is the most abundant energy resource available, photovoltaic solar cells must consist of sufficiently abundant and environmentally friendly elements, for scalable low-cost production to provide a major amount of the world's energy supply. However, scalability is limited in current thin-film solar cell technologies based on Cu(In,Ga)(S,Se)2 and CdTe due to scarce, expensive, and toxic elements. Thin-film solar cells consisting of earth-abundant and non-toxic materials were made from pulsed chemical vapor deposition (pulsed-CVD) of SnS as the p-type absorber layer and atomic layer deposition (ALD) of Zn(O,S) as the n-type buffer layer. Solar cells with a structure of Mo/SnS/Zn(O,S)/ZnO/ITO were studied by varying the synthesis conditions of the SnS and Zn(O,S) layers. Annealing SnS in hydrogen sulfide increased the mobility by more than one order of magnitude, and improved the power conversion efficiency of the solar cell devices. Solar cell performance can be further optimized by adjusting the stoichiometry of Zn(O,S), and by tuning the electrical properties of Zn(O,S) through various in situ or post-annealing treatments. Zn(O,S) can be post-annealed in oxygen atmosphere or doped with nitrogen, by ammonium hydroxide or ammonia gas, during the ALD growth to reduce the carrier concentration, which can be critical for reducing interface recombination at the p-n junction. High carrier concentration buffer layers can be critical for reducing contact resistance with the ITO layer. Zn(O,S) can also be incorporated with aluminum by trimethylaluminum (TMA) doses to either increase or decrease the carrier concentration based on the stoichiometry of Zn(O,S).

  12. Investigation of the effect of anodization time and annealing temperature on the physical properties of ZrO2 thin film on a Si substrate

    NASA Astrophysics Data System (ADS)

    Goh, Kian Heng; Lee, Hui Jing; Lau, Sze Kuan; Chiew Teh, Pei; Ramesh, S.; Tan, Chou Yong; Hoong Wong, Yew

    2017-08-01

    This research work studied the effects of various anodization times (5, 10, 15, 20 and 25 min) and various annealing temperatures (500, 600, 700, 800 and 900 °C) on ZrO2 thin film on a Si substrate. The ZrO2 thin film was prepared via sputtering and anodization processes on a Si substrate. The existence of Si, SiO2, m-ZrO2, t-ZrO2 and ZrSiO4 was confirmed by x-ray diffraction, Fourier transform infrared microscopy and Raman spectroscopy. In addition, NaOH was observed as a residue on the surface of the thin film. The grain size and microstrain of both m-ZrO2, and t-ZrO2 were calculated using the Williamson-Hall and/or Scherrer equation. The morphology of samples was examined by scanning electron microscopy. In contrast to unannealed samples, the annealed samples have a smaller grain size, less NaOH, and SiO2 with a smoother surface. However, the SiO2 existed when being annealed at higher temperatures (⩾800 °C).

  13. 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.

  14. 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.

  15. Controllable Electrochemical Synthesis of Reduced Graphene Oxide Thin-Film Constructed as Efficient Photoanode in Dye-Sensitized Solar Cells

    PubMed Central

    Chong, Soon Weng; Lai, Chin Wei; Abd Hamid, Sharifah Bee

    2016-01-01

    A controllable electrochemical synthesis to convert reduced graphene oxide (rGO) from graphite flakes was introduced and investigated in detail. Electrochemical reduction was used to prepare rGO because of its cost effectiveness, environmental friendliness, and ability to produce rGO thin films in industrial scale. This study aimed to determine the optimum applied potential for the electrochemical reduction. An applied voltage of 15 V successfully formed a uniformly coated rGO thin film, which significantly promoted effective electron transfer within dye-sensitized solar cells (DSSCs). Thus, DSSC performance improved. However, rGO thin films formed in voltages below or exceeding 15 V resulted in poor DSSC performance. This behavior was due to poor electron transfer within the rGO thin films caused by poor uniformity. These results revealed that DSSC constructed using 15 V rGO thin film exhibited high efficiency (η = 1.5211%) attributed to its higher surface uniformity than other samples. The addition of natural lemon juice (pH ~ 2.3) to the electrolyte accelerated the deposition and strengthened the adhesion of rGO thin film onto fluorine-doped tin oxide (FTO) glasses. PMID:28787869

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Synthesis of TiN/a-Si3N4 thin film by using a Mather type dense plasma focus system

    NASA Astrophysics Data System (ADS)

    Hussain, T.; R., Ahmad; Khalid, N.; A. Umar, Z.; Hussnain, A.

    2013-05-01

    A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness (root-mean-square).

  2. Optimal design of light trapping in thin-film solar cells enhanced with graded SiNx and SiOxNy structure.

    PubMed

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

    2012-05-07

    In this paper, a graded SiNx and SiOxNy structure is proposed as antireflection coatings deposited on top of amorphous silicon (α-Si) thin-film solar cell. The structural parameters are optimized by differential evolution in order to enhance the optical absorption of solar cells to the greatest degree. The optimal design result demonstrates that the nonlinear profile of dielectric constant is superior to the linear profile, and discrete multilayer graded antireflection coatings can outperform near continuously graded antireflection coatings. What's more, the electric field intensity distributions clearly demonstrate the proposed graded SiNx and SiOxNy structure can remarkably increase the magnitude of electric field of a-Si:H layer and hence, enhance the light trapping of a-Si:H thin-film solar cells in the whole visible and near-infrared spectrum. Finally, we have compared the optical absorption enhancements of proposed graded SiNx and SiOxNy structure with nanoparticles structure, and demonstrated that it can result in higher enhancements compared to the dielectric SiC and TiO2 nanoparticles. We have shown that the optimal graded SiNx and SiOxNy structure optimized by differential evolution can reach 33.31% enhancement which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC and TiO2 nanoparticles.

  3. 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.

  4. Laser textured substrates for light in-coupling in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Chakanga, Kambulakwao; Siepmann, Ortwin; Sergeev, Oleg; Geißendörfer, Stefan; von Maydell, Karsten; Agert, Carsten

    2014-03-01

    In this work we investigate the use of a picosecond (ps) laser used for monolithic connection to pattern glass substrates to achieve light in-coupling in silicon thin film solar cells. We present our results on the patterning of three commercially available and frequently used multi-component glasses Corning EAGLE XG®, Schott BOROFLOAT® 33 and Saint-Gobain SGG DIAMANT®. We find that the different glass structural components influence the degree of texturing obtained. This can be attributed to the different laser induced electron collision times and recombination rates, and thus the critical electron density evolution leading to ablation. Thus the ablated crater profile is glass composition dependent. The surface texture is altered from periodic to random with decreasing scribing speed. The transmission of the textured substrates gradually decreases while the reflection increases as a consequence of the topological and morphological changes. The angular resolved measurements illustrate that highly textured substrates scatter the light towards greater angles. This demonstrates potential for the application in substrate configuration (nip) thin film solar cells, as the scattering can increase the optical path, and hence the absorption in the absorber layer. Simulations of periodically textured glass substrates demonstrate a focused optical generation rate near the front contact and absorber layer interface. The influence of the modified refractive index region on the optical generation rate and reflection depends on the crater profile. The reflection is generally reduced when a periodic texture in the micrometre range is implemented.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Spatially Resolved Cathodoluminescence of CdTe Thin Films and Solar Cells

    SciTech Connect

    Romero, M. J.; Metzger, W.; Gessert, T. A.; Albin, D. S.; Al-Jassim, M. M.

    2003-05-01

    We have investigated the spatial distribution of different transitions identified in the emission spectra of CdTe thin films and solar cells by cathodoluminescence spectroscopic imaging (CLSI). Prior to back-contact deposition, the spectra are dominated by excitons (X) and donor-to-acceptor (DAP) transitions. After contacting, Cu acceptor states are found in addition to the X and DAP recombination processes. A very systematic behavior found in CdTe is that DAP transitions occur preferentially at grain boundaries (GBs). The distribution of these states responsible for the passivation of GBs is not affected by further processing, although additional levels participate in the recombination process. We believe that this stability is one of the reasons for the success of thin-film CdTe solar cells. Estimates of the densities of different donors and acceptors participating in the recombination process are possible from the analysis of the evolution of the emission spectra with the excitation level. It is found that the back contact suppresses some intrinsic acceptors (associated with the A center) near the back-contact interface and, therefore, Cu acceptor states should be responsible for the p-typeness of the back surface more than a reduction of compensation. CLSI measurements are shown to be helpful in understanding the physics of back-contact formation.

  10. 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%.

  11. 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%.

  12. 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.

  13. Plasmonic and photonic designs for light trapping in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ji, Liming

    Thin film solar cells are promising to realize cheap solar energy. Compared to conventional wafer cells, they can reduce the use of semiconductor material by 90%. The efficiency of thin film solar cells, however, is limited due to insufficient light absorption. Sufficient light absorption at the bandgap of semiconductor requires a light path more than 10x the thickness of the semiconductor. Advanced designs for light trapping are necessary for solar cells to absorb sufficient light within a limited volume of semiconductor. The goal is to convert the incident light into a trapped mode in the semiconductor layer. In this dissertation, a critical review of currently used methods for light trapping in solar cells is presented. The disadvantage of each design is pointed out including insufficient enhancement, undesired optical loss and undesired loss in carrier transport. The focus of the dissertation is light trapping by plasmonic and photonic structures in thin film Si solar cells. The performance of light trapping by plasmonic structures is dependent on the efficiency of photon radiation from plasmonic structures. The theory of antenna radiation is used to study the radiation by plasmonic structures. In order to achieve efficient photon radiation at a plasmonic resonance, a proper distribution of surface charges is necessary. The planar fishnet structure is proposed as a substitution for plasmonic particles. Large particles are required in order to resonate at the bandgap of semiconductor material. Hence, the resulting overall thickness of solar cells with large particles is large. Instead, the resonance of fishnet structure can be tuned without affecting the overall cell thickness. Numerical simulation shows that the enhancement of light absorption in the active layer is over 10x compared to the same cell without fishnet. Photons radiated from the resonating fishnet structure travel in multiple directions within the semiconductor layer. There is enhanced field

  14. Development of Thin Film Silicon Solar Cell Using Inkjet Printed Silicon and Other Inkjet Processes: Cooperative Research and Development Final Report, CRADA Number CRD-07-260

    SciTech Connect

    Sopori, B.

    2012-04-01

    The cost of silicon photovoltaics (Si-PV) can be greatly lowered by developing thin-film crystalline Si solar cells on glass or an equally lower cost substrate. Typically, Si film is deposited by thermal evaporation, plasma enhanced chemical vapor deposition, and sputtering. NREL and Silexos have worked under a CRADA to develop technology to make very low cost solar cells using liquid organic precursors. Typically, cyclopentasilane (CPS) is deposited on a glass substrate and then converted into an a-Si film by UV polymerization followed by low-temperature optical process that crystallizes the amorphous layer. This technique promises to be a very low cost approach for making a Si film.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Structural design of photonic crystal thin film silicon solar cells by sensitivity analysis: Inclusion of electrode absorption.

    PubMed

    Kawamoto, Yosuke; Tanaka, Yoshinori; Ishizaki, Kenji; De Zoysa, Menaka; Asano, Takashi; Noda, Susumu

    2015-07-27

    We carry out the structural design of photonic crystals (PCs) using sensitivity analysis for enhancing optical absorption of thin film microcrystalline silicon (μc-Si) solar cells. In this paper, we employ a model which includes absorption of not only the thin film μc-Si, but also the transparent conductive oxide and metal back reflector for design accuracy. We carry out structural design for this model using sensitivity analysis which maximizes optical absorption in μc-Si layer. As a result, we succeed in obtaining the maximum short circuit current density of 25.2 mA/cm2 for thin film (600-nm thick) μc-Si solar cells (1.4-fold increase compared to the case without a PC).

  20. 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.

  1. Thin film poly-Si solar cell with ``STAR structure`` on glass substrate fabricated at low temperature

    SciTech Connect

    Yamamoto, Kenji; Yoshimi, Masashi; Suzuki, Takayuki; Okamoto, Yoshifumi; Tawada, Yuko; Nakajima, Akihiko

    1997-12-31

    The performances of thin film poly-Si solar cells with a thickness of less than 5 {micro}m on a glass substrate have been systematically investigated as a function of thickness. The cell of glass/back reflector/n-i-p poly-Si/ITO is well characterized by the structure of naturally surface texture and enhanced absorption with a back reflector (STAR), where the active i-layer was fabricated by plasma chemical vapor deposition (CVD) at low temperature. The cell with a thickness of 3.5 {micro}M and 2.5 {micro}m demonstrated an intrinsic efficiency of 9.8%, as independently confirmed by Japan Quality Assurance. The optical confinement effect explains the excellent spectral response at long wavelength for the cells through the PC1D analysis. The higher sensitivity at long-wavelength of the cell appeared in quantum efficiency curves is well correlated to the result of reflectance measurement. The open circuit voltage of 0.526 mV and the efficiency of 9.3% has been achieved for the cell with a thickness of 1.5 {micro}m, which was proved to be entirely stable with respect to the light-soaking. The stabilized efficiency of the developed a-Si:H/poly-Si/poly-Si stacked solar cell exhibits the efficiency of 11.5%.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Enhanced photon management in silicon thin film solar cells with different front and back interface texture

    PubMed Central

    Tamang, Asman; Hongsingthong, Aswin; Jovanov, Vladislav; Sichanugrist, Porponth; Khan, Bakhtiar A.; Dewan, Rahul; Konagai, Makoto; Knipp, Dietmar

    2016-01-01

    Light trapping and photon management of silicon thin film solar cells can be improved by a separate optimization of the front and back contact textures. A separate optimization of the front and back contact textures is investigated by optical simulations taking realistic device geometries into consideration. The optical simulations are confirmed by experimentally realized 1 μm thick microcrystalline silicon solar cells. The different front and back contact textures lead to an enhancement of the short circuit current by 1.2 mA/cm2 resulting in a total short circuit current of 23.65 mA/cm2 and an energy conversion efficiency of 8.35%. PMID:27481226

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Interfacial alkali diffusion control in chalcopyrite thin-film solar cells.

    PubMed

    Ishizuka, Shogo; Yamada, Akimasa; Fons, Paul J; Shibata, Hajime; Niki, Shigeru

    2014-08-27

    Alkali elements, specifically sodium (Na), are key materials to enhance the energy conversion efficiencies of chalcopyrite and related thin-film photovoltaic solar cells. Recently, the effect of potassium (K) has also attracted attention because elemental K has unique effects different from Na as well as a similar beneficial effect in improving device performance. In this study, the control of selective alkali K and Na diffusion into chalcopyrite thin-films from soda-lime glass substrates, which serve as the monolithic alkali source material and contain both K and Na, is demonstrated using ternary CuGaSe2. Elemental K is found to be incorporated in the several ten nanometer thick Cu-deficient region, which is formed on the CuGaSe2 film surface, while Na is ejected, although both K and Na diffuse from the substrate to the CuGaSe2 film surface during growth. The alkali [K]/[Na] concentration ratio in the surface region of CuGaSe2 films strongly depends on the film structure and can be controlled by growth parameters under the same substrate temperature conditions. The results we present here offer new concepts necessary to explore and develop emerging new chalcopyrite and related materials and optimize their applications.

  16. 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.

  17. Electron and hole drift mobility measurements on thin film CdTe solar cells

    SciTech Connect

    Long, Qi; Dinca, Steluta A.; Schiff, E. A.; Yu, Ming; Theil, Jeremy

    2014-07-28

    We report electron and hole drift mobilities in thin film polycrystalline CdTe solar cells based on photocarrier time-of-flight measurements. For a deposition process similar to that used for high-efficiency cells, the electron drift mobilities are in the range of 10{sup −1}–10{sup 0} cm{sup 2}/V s, and holes are in the range of 10{sup 0}–10{sup 1} cm{sup 2}/V s. The electron drift mobilities are about a thousand times smaller than those measured in single crystal CdTe with time-of-flight; the hole mobilities are about ten times smaller. Cells were examined before and after a vapor phase treatment with CdCl{sub 2}; treatment had little effect on the hole drift mobility, but decreased the electron mobility. We are able to exclude bandtail trapping and dispersion as a mechanism for the small drift mobilities in thin film CdTe, but the actual mechanism reducing the mobilities from the single crystal values is not known.

  18. Optical and electrical characterization of CdS-Glycine thin films with ammonia free buffer grown at different temperatures for solar cells applications

    NASA Astrophysics Data System (ADS)

    Berman-Mendoza, D.; Quiñones-Urías, D.; Ferra-González, S.; Vera-Marquina, A.; Rojas-Hernández, A.; Gómez Fuentes, R.; García-Juárez, A.; Leal-Cruz, A. L.; Ramos-Carrasco, A.

    2013-11-01

    In this work we report the fabrication and electro-optical characterization of CdS thin films using glycine as complexing agent with ammonia and ammonia free buffer by the Chemical Bath Deposition (CBD) method. The CdS thin films were grown at different temperatures of 50, 60, 70 and 80 °C in a thermal water bath. The morphology of these films was determined using atomic force microscopy; the resultant films were homogeneous, well adhered to the substrate, and specularly reflecting with a varying color depending on the deposition temperature. Transmittance and reflectance measurements of thermally treated CdS films were carried to study the effect of the ammonia buffer on its optical properties and bandgap. The crystallinity of the CdS thin films was determined by means of X Ray diffraction measurements. Therefore, for this study, an ammonia-free complexing agent has been taken for the deposition of CdS. Among different methods, which are being used for the preparation of CdS films, Chemical Bath Deposition (CBD) is the most attractive due to its low cost, easy to handle and large possibilities regarding doping and deposition on various substrates. In particular it can be used to easily obtain field effect devices by depositing CdS thin films over a SiO2/Si substrate. Heterostructures with interesting physical properties can be imagined, realized and tested in this way.. Structures CdS/PbS also were realized and have shown good solar cell characteristics.

  19. Electron-reflector strategy for cadmium telluride thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Hsiao, Kuo-Jui

    The CdTe thin-film solar cell has a large absorption coefficient and high theoretical efficiency. Moreover, large-area photovoltaic panels can be economically fabricated. These features potentially make the CdTe thin-film solar cell the leading alternative energy source. However, the record CdTe efficiency (16.5%) is much less than its theoretical maximum efficiency (29%), primarily because the open-circuit voltage (0.845 V) is well below what is expected for its band gap (1.5 eV). The incorporation of an electron reflector is a strategy to improve the open-circuit voltage of solar cells, and thus a strong possibility to improve the efficiency of CdTe thin-film solar cells. An electron reflector is a conduction-band energy barrier at the back surface of the solar cell, which can reduce the recombination due to the electron flow to the back surface. Different methods to create an electron reflector are explained in the thesis: (1) expanded band gap, either an expanded-band-gap layer or a bulk-band-gap reduction, and (2) alteration to the band bending through a reversed back barrier or a heavily-doped back surface. Investigation shows that the expanded-band-gap layer is the most efficient and practical mechanism for an electron reflector, and the combination of any two mechanisms does not yield additional improvement. To have the optimal effect from the electron-reflector strategy, reasonable CdTe lifetime (1 ns or above) and full depletion of the CdTe layer are required to ensure high carrier collection. Furthermore, a good-quality reflector interface between the p-type CdTe layer and the electron-reflector layer is essential. Preliminary experimental evidence has shown that CdTe cells with a ZnTe back layer do have a slightly higher open-circuit voltage. An electron reflector should be particularly beneficial for thin (less than 2 microm) CdTe cells which have a fully-depleted CdTe absorber layer. Thin CdTe cells can also benefit from the optical reflection at the

  20. 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

  1. 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.

  2. 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.

  3. Anti-reflective microstructure array and its performance evaluation in thin film flexible solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Zhan, Xinghua; Gao, Mengyu; Tie, Shengnian; Gao, Wei

    2017-07-01

    The anti-reflective (AR) structure greatly reduces the light reflection. When it is applied on solar cells, it enables more light to be absorbed by the cells, increasing the energy of the incident light and improving the light-to-electricity conversion efficiency. In this study, the optical properties of AR microstructures are investigated followed by the performance evaluation of solar cells. The AR microstructure is arrayed in a uniform and periodic fashion. When it is applied on PMMA, only 1.0% of the light is reflected away while 2.6% of the light is reflected on glass. The angular dependence performance is also improved with AR structure with 9.4% more light absorption, which can increase the effective energy generation duration for the solar cell. The AR structure is applied to amorphous silicon thin film solar cells by nano-imprinting technology. The solar cell with AR structure gained 8.63% more power compared to the conventional solar cells.

  4. On the way to enhance the optical absorption of a-Si in NIR by embedding Mg{sub 2}Si thin film

    SciTech Connect

    Chernev, I. M. Shevlyagin, A. V.; Galkin, K. N.; Stuchlik, J.; Fajgar, R.; Galkin, N. G.

    2016-07-25

    Mg{sub 2}Si thin film was embedded in amorphous silicon matrix by solid phase epitaxy. The structure and optical properties were investigated by electron energy loss, X-ray photoelectron, Raman, and photo thermal deflection spectroscopy measurements. It was found that in the photon energy range of 0.8–1.7 eV, the light absorption of the structure with magnesium silicide (Mg{sub 2}Si) film embedded in a-Si(i) matrix is 1.5 times higher than that for the same structure without Mg{sub 2}Si.

  5. Transparent TiO2 nanowire networks via wet corrosion of Ti thin films for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shin, Eunhye; Jin, Saera; Hong, Jongin

    2017-09-01

    Transparent TiO2 nanowire networks were prepared by corrosion of Ti thin films on F-doped SnO2 glass substrates in an alkaline (potassium hydroxide: KOH) solution. The formation of the porous TiO2 nanostructures from the Ti thin films was thoroughly investigated. Dye-sensitized solar cells with a photoanode of 1.2-μm-thick nanowire networks exhibit an average optical transmittance of 40% in the visible light region and a power conversion efficiency of 1.0% under one sun illumination.

  6. 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 %.

  7. 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.

  8. 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.

  9. 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.

  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. Electrical detection of Rabi oscillations in microcrystalline silicon thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Meier, C.; Behrends, J.; Bittl, R.

    2013-10-01

    The microscopic structure of light-activated paramagnetic conduction band tail states and their participation in spin-dependent hopping transport is studied in a microcrystalline silicon thin-film solar cell. Application of X- and S-band electrically detected magnetic resonance (EDMR) experiments in combination with numerical simulations of Rabi oscillations indicates that the spin-dependent process takes place between two neighbouring band tail states. For sufficiently high microwave (mw) power, two Rabi frequencies Ω1 and Ω2 = 2Ω1 show up in the coherent EDMR signals. An analysis of their relative contributions to the Rabi traces suggests that the g-values of both spin partners are not correlated for the majority of the EDMR-active pairs. A small fraction of doublet pairs with similar g-values may explain the appearance of a larger Ω2 contribution than predicted by the simulations.

  13. 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%.

  14. 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).

  15. 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.

  16. 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.

  17. 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.

  18. Scalable Production of Mechanically Robust Antireflection Film for Omnidirectional Enhanced Flexible Thin Film Solar Cells

    PubMed Central

    Wang, Min; Ma, Pengsha; Lu, Linfeng; Lin, Yinyue; Chen, Xiaoyuan; Jia, Wei; Cao, Xinmin; Chang, Paichun

    2017-01-01

    Antireflection (AR) at the interface between the air and incident window material is paramount to boost the performance of photovoltaic devices. 3D nanostructures have attracted tremendous interest to reduce reflection, while the structure is vulnerable to the harsh outdoor environment. Thus the AR film with improved mechanical property is desirable in an industrial application. Herein, a scalable production of flexible AR films is proposed with microsized structures by roll‐to‐roll imprinting process, which possesses hydrophobic property and much improved robustness. The AR films can be potentially used for a wide range of photovoltaic devices whether based on rigid or flexible substrates. As a demonstration, the AR films are integrated with commercial Si‐based triple‐junction thin film solar cells. The AR film works as an effective tool to control the light travel path and utilize the light inward more efficiently by exciting hybrid optical modes, which results in a broadband and omnidirectional enhanced performance. PMID:28932667

  19. 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

  20. 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.

  1. CdS/CdTe Thin-Film Solar Cell with a Zinc Stannate Buffer Layer

    SciTech Connect

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

    1998-10-28

    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

  2. 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.

  3. 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.

  4. Impact of Sodium Contamination in Tin Sulfide Thin-Film Solar Cells

    DOE PAGES

    Steinmann, Vera; Brandt, Riley E.; Chakraborty, Rupak; ...

    2016-02-12

    Empirical observations show that sodium(Na) is a benign contaminant in some thin-filmsolar cells. Here, we intentionally contaminate thermally evaporated tin sulfide (SnS)thin-films with sodium and measure the SnS absorber properties and solar cellcharacteristics. The carrier concentration increases from 2 × 1016 cm-3 to 4.3 × 1017 cm-3 in Na-doped SnSthin-films, when using a 13 nm NaCl seed layer, which is detrimental for SnS photovoltaic applications but could make Na-doped SnS an attractive candidate in thermoelectrics. We observed trends in carrier concentration and found that it is in good agreement with density functional theory calculations, which predict an acceptor-type NaSn defectmore » with low formation energy.« less

  5. 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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Intercalation crystallization of phase-pure α-HC(NH₂)₂PbI₃ upon microstructurally engineered PbI₂ thin films for planar perovskite solar cells.

    PubMed

    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 (α-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 α-HC(NH2)2PbI3 perovskite thin films. Planar perovskite solar cells fabricated using these thin films deliver power conversion efficiency (PCE) up to 13.8%.

  7. Amorphous thin films for solar-cell applications. Final report, September 11, 1978-September 10, 1979

    SciTech Connect

    Carlson, D E; Balberg, I; Crandall, R S; Goldstein, B C; Hanak, J J; Pankove, J I; Staebler, D L; Weakliem, H A; Williams, R

    1980-02-01

    In Section II, Theoretical Modeling, theories for the capture of electrons by deep centers in hydrogenated amorphous silicon (a-Si:H) and for field-dependent quantum efficiency in a-Si:H are presented. In Section III, Deposition and Doping Studies, the optimization of phosphorus-doped a-Si:H carried out in four different discharge systems is described. Some details of the dc proximity and rf magnetron discharge systems are also provided. Preliminary mass spectroscopy studies of the rf magnetron discharge in both SiH/sub 4/ and SiF/sub 4/ are presented. In Section IV, Experimental Methods for Characterizing a-Si:H, recent work involving photoluminescence of fluorine-doped a-Si:H, photoconductivity spectra, the photoelectromagnetic effect, the photo-Hall effect and tunneling into a-Si:H is presented. Also, studies of the growth mechanism of Pt adsorbed on both crystalline Si and a-Si:H are described. Measurements of the surface photovoltage have been used to estimate the distribution of surface states of phosphorus-doped and undoped a-Si:H. Section V, Formation of Solar-Cell Structures, contains information on stacked or multiple-junction a-Si:H solar cells. In Section VI, Theoretical and Experimental Evaluation of Solar-Cell Parameters, an upper limit of approx. = 400 A is established for the hole diffusion length in undoped a-Si:H. A detailed description of carrier generation, recombination and transport in a-Si:H solar cells is given. Finally, some characteristics of Pd-Schottky-barrier cells are described for different processing histories.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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%.

  15. Research on polycrystalline thin-film CuGaInSe[sub 2] solar cells

    SciTech Connect

    Stanbery, B.J.; Chen, W.S.; Devaney, W.E.; Stewart, J.W. . Defense and Space Systems Group)

    1992-11-01

    This report describes research to fabricate high-efficiency CdZnS/CuInGaSe[sub 2] (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% efficient, 1-cm[sup 2]-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[sub 0.82]Zn[sub 0.18]S/CuIn[sub 0.80]Ga[sub 0.20]Se[sub 2] cell that was verified at NREL under standard testing conditions at 13.1% efficiency with V[sub oc] = 0.581 V, J[sub sc] = 34.8 mA/cm[sup 2], FF = 0.728, and a cell area of 0.979 cm[sup 2].

  16. Reduced electrical performance of Zn enriched ZnTe nanoinclusion semiconductors thin films for buffer layer in solar cells

    NASA Astrophysics Data System (ADS)

    Mahmood, Waqar; Thomas, Andrew; Haq, Anwar ul; Shah, Nazar Abbas; Farooq Nasir, Muhammad

    2017-06-01

    Closed space sublimation (CSS) technique was employed to deposit thin films of zinc telluride (ZnTe) on a glass substrate under high vacuum. Two sets of ZnTe thin films and Zn enriched ZnTe thin films were prepared for comparative study. The enrichment for Zn onto the as-deposited ZnTe thin films was done by the novel manner of layer by layer deposition with subsequent annealing. X-ray diffraction (XRD) studies revealed before and after the enrichment of Zn the preferred orientation is [1 1 1] having cubic phase. The lattice constant was found to be increased and the crystallite size decreased 28 nm to 24 nm after the enrichment of Zn. A morphological study was carried out through a scanning electron microscope (SEM). For Zn enriched samples the average grain size is smaller as compared to ZnTe thin films. The local compositions of Zn and Te were confirmed by energy dispersive x-rays (EDX) from 51 atomic % of as-deposited ZnTe thin films to 68 atomic % in Zn enriched ZnTe thin films. The Zn enriched samples have a slight decrease in optical transmission in UV-VIS-NIR range as compared to the as-deposited ZnTe thin films. Due to the deposition of Zn there is a very small change in optical band gap energy. A four-probe technique was used to study electrical properties of as-deposited and Zn-enriched ZnTe thin films. These results shows that the as-deposited samples had the resistivity of 106 Ω · cm. For Zn enrichment samples resistivity increases from 106 Ω · cm to 108 Ω · cm, which shows that Zn-enriched samples are not suitable for back contact of II-VI solar cells. X-rays photoelectron spectroscopy (XPS) was used to confirm the elemental compositions and its bonding strength before and after the enrichment of Zn.

  17. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    SciTech Connect

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2016-05-21

    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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Natural evolution inspired design of light trapping structure in thin film organic solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-09-01

    Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

  4. 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.

  5. 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

  6. 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.

  7. Organic solar cells based on liquid crystalline and polycrystalline thin films

    NASA Astrophysics Data System (ADS)

    Yoo, Seunghyup

    This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors. Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements. In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7% under broadband illumination (350--900 nm) with a peak external quantum efficiency of 58% have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using

  8. Design rules for net absorption enhancement in pseudo-disordered photonic crystal for thin film solar cells.

    PubMed

    Ding, He; Lalouat, Loïc; Gonzalez-Acevedo, Bastian; Orobtchouk, Régis; Seassal, Christian; Drouard, Emmanuel

    2016-03-21

    The role of pseudo-disordered photonic crystals on the absorption efficiency of simplified thin film crystalline silicon solar cells is presented and discussed. The expected short circuit current can thus be further increased compared to a fully optimized square lattice of holes, thanks to carefully controlled positions of the nanoholes in the considered realistic simplified solar cell stack. In addition, the pseudo-disordered structures are less sensitive to the angle of incidence, especially in the long wavelength range.

  9. Effect of back reflectors on photon absorption in thin-film amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Hossain, Mohammad I.; Qarony, Wayesh; Hossain, M. Khalid; Debnath, M. K.; Uddin, M. Jalal; Tsang, Yuen Hong

    2017-08-01

    In thin-film solar cells, the photocurrent conversion productivity can be distinctly boosted-up utilizing a proper back reflector. Herein, the impact of different smooth and textured back reflectors was explored and effectuated to study the optical phenomena with interface engineering strategies and characteristics of transparent contacts. A unique type of wet-chemically textured glass-substrate 3D etching mask used in superstrate (p-i-n) amorphous silicon-based solar cell along with legitimated back reflector permits joining the standard light-trapping methodologies, which are utilized to upgrade the energy conversion efficiency (ECE). To investigate the optical and electrical properties of solar cell structure, the optical simulations in three-dimensional measurements (3D) were performed utilizing finite-difference time-domain (FDTD) technique. This design methodology allows to determine the power losses, quantum efficiencies, and short-circuit current densities of various layers in such solar cell. The short-circuit current densities for different reflectors were varied from 11.50 to 13.27 and 13.81 to 16.36 mA/cm2 for the smooth and pyramidal textured solar cells, individually. Contrasted with the comparable flat reference cell, the short-circuit current density of textured solar cell was increased by around 24%, and most extreme outer quantum efficiencies rose from 79 to 86.5%. The photon absorption was fundamentally improved in the spectral region from 600 to 800 nm with no decrease of photocurrent shorter than 600-nm wavelength. Therefore, these optimized designs will help to build the effective plans next-generation amorphous silicon-based solar cells.

  10. 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.

  11. Back surface studies of Cu(In,Ga)Se2 thin film solar cells

    NASA Astrophysics Data System (ADS)

    Simchi, Hamed

    Cu(In,Ga)Se2 thin film solar cells have attracted a lot of interest because they have shown the highest achieved efficiency (21%) among thin film photovoltaic materials, long-term stability, and straightforward optical bandgap engineering by changing relative amounts of present elements in the alloy. Still, there are several opportunities to further improve the performance of the Cu(In,Ga)Se2 devices. The interfaces between layers significantly affect the device performance, and knowledge of their chemical and electronic structures is essential in identifying performance limiting factors. The main goal of this research is to understand the characteristics of the Cu(In,Ga)Se2-back contact interface in order to design ohmic back contacts for Cu(In,Ga)Se2-based solar cells with a range of band gaps and device configurations. The focus is on developing either an opaque or transparent ohmic back contact via surface modification or introduction of buffer layers in the back surface. In this project, candidate back contact materials have been identified based on modeling of band alignments and surface chemical properties of the absorber layer and back contact. For the first time, MoO3 and WO 3 transparent back contacts were successfully developed for Cu(In,Ga)Se 2 solar cells. The structural, optical, and surface properties of MoO 3 and WO3 were optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. Valence band edge energies were also obtained by analysis of the XPS spectra and used to characterize the interface band offsets. As a result, it became possible to illuminate of the device from the back, resulting in a recently developed "backwall superstrate" device structure that outperforms conventional substrate Cu(In,Ga)Se2 devices in the absorber thickness range 0.1-0.5 microm. Further enhancements were achieved by introducing moderate amounts of Ag into the Cu(In,Ga)Se2 lattice during the co-evaporation method

  12. 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

  13. 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.

  14. 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.

  15. 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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Surface oxidation of polycrystalline cadmium telluride thin films for Schottky barrier junction solar cells

    NASA Astrophysics Data System (ADS)

    Yi, X.; Liou, J. J.

    1995-06-01

    Polycrystalline CdTe thin films grown on graphite or tungsten-coated graphite substrates by chemical vapor deposition (CVD) were exposed to the air at room temperature in a natural atmosphere of about 60% air humidity for 6 months. X-ray photoemission spectroscopy (XPS) and Auger electron spectroscopy (AES) of the films indicate that a tellurium dioxide (TeO 2) overlayer has formed from this process. The effects of such an overlayer on the electrical property of polycrystalline CdTe-based Schottky barrier junction solar cells have also been discussed for the first time. It is shown that a solar cell formed on a CdTe film with TeO 2 overlayer has considerably higher open-circuit voltage and fill factor than that formed on a CdTe film without TeO 2 overlayer. Our study further indicates that using a polycrystalline CdTe film which is thermally oxidized at above room temperature (100-400°C) does not provide any improvement on the solar cell efficiency.

  17. Impacts of Temperature on the Performance of Cdte Based Thin-Film Solar Cell

    NASA Astrophysics Data System (ADS)

    Asaduzzaman, Md.; Newaz Bahar, Ali; Maksudur Rahman Bhuiyan, Mohammad; Habib, Md. Ahsan

    2017-08-01

    In this investigation, the effect of temperature on the performance of CdTe based thin film solar cells has been studied. The parameters such as open circuit voltage (Voc ), short circuit current density (Jsc ), fill factor and efficiency η determines the performance of solar cell. And an important diode parameter, reverse saturation current density, J 0 controls the impacts of temperature on the performance parameters. The reverse saturation current density of the CdTe photovoltaic cell, J 0 = CT 3exp(‑qEg /kT) was determinedas optimum for C = 17.90 mAcm ‑2 K 3 yields CT 3 = 4.74 × 108 mAcm ‑2. In this case, 298 K is considered to be more suitable temperature to achieve optimized Voc, Jsc, FF, and η calculated for AM1.5G illumination spectra. The maximum attained values of performance parameters are compared with the experimental and theoretical results in the literature of CdTe solar cells. Moreover, the rate of change in performance parameters due to temperature are also measured and compared with the results available in the earlier published works.

  18. 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.

  19. 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.

  20. Photonic light-trapping versus Lambertian limits in thin film silicon solar cells with 1D and 2D periodic patterns.

    PubMed

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

    2012-03-12

    We theoretically investigate the light-trapping properties of one- and two-dimensional periodic patterns etched on the front surface of c-Si and a-Si thin film solar cells with a silver back reflector and an anti-reflection coating. For each active material and configuration, absorbance A and short-circuit current density Jsc are calculated by means of rigorous coupled wave analysis (RCWA), for different active materials thicknesses in the range of interest of thin film solar cells and in a wide range of geometrical parameters. The results are then compared with Lambertian limits to light-trapping for the case of zero absorption and for the general case of finite absorption in the active material. With a proper optimization, patterns can give substantial absorption enhancement, especially for 2D patterns and for thinner cells. The effects of the photonic patterns on light harvesting are investigated from the optical spectra of the optimized configurations. We focus on the main physical effects of patterning, namely a reduction of reflection losses (better impedance matching conditions), diffraction of light in air or inside the cell, and coupling of incident radiation into quasi-guided optical modes of the structure, which is characteristic of photonic light-trapping.

  1. 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%.

  2. 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.

  3. Alternative buffer layer development in Cu(In,Ga)Se2 thin film solar cells

    NASA Astrophysics Data System (ADS)

    Xin, Peipei

    Cu(In,Ga)Se2-based thin film solar cells are considered to be one of the most promising photovoltaic technologies. Cu(In,Ga)Se2 (CIGS) solar devices have the potential advantage of low-cost, fast fabrication by using semiconductor layers of only a few micrometers thick and high efficiency photovoltaics have been reported at both the cell and the module levels. CdS via chemical bath deposition (CBD) has been the most widely used buffer option to form the critical junction in CIGS-based thin film photovoltaic devices. However, the disadvantages of CdS can’t be ignored - regulations on cadmium usage are getting stricter primarily due to its toxicity and environmental impacts, and the proper handling of the large amount of toxic chemical bath waste is a massive and expensive task. This dissertation is devoted to the development of Cd-free alternative buffer layers in CIGS-based thin film solar cells. Based on the considerations of buffer layer selection criteria and extensive literature review, Zn-compound buffer materials are chosen as the primary investigation candidates. Radio frequency magnetron sputtering is the preferred buffer deposition approach since it’s a clean and more controllable technique compared to CBD, and is readily scaled to large area manufacturing. First, a comprehensive study of the ZnSe1-xOx compound prepared by reactive sputtering was completed. As the oxygen content in the reactive sputtering gas increased, ZnSe1-xOx crystallinity and bandgap decreased. It’s observed that oxygen miscibility in ZnSe was low and a secondary phase formed when the O2 / (O2 + Ar) ratio in the sputtering gas exceeded 2%. Two approaches were proposed to optimize the band alignment between the CIGS and buffer layer. One method focused on the bandgap engineering of the absorber, the other focused on the band structure modification of the buffer. As a result, improved current of the solar cell was achieved although a carrier transport barrier at the junction

  4. Preparation of H2SO4 doped Polyaniline thin film solar cells by spin coating technique

    NASA Astrophysics Data System (ADS)

    Patel, Abhishek; Pataniya, Pratik; Patel, K. D.; Solanki, G. K.; Pathak, V. M.

    2017-05-01

    A water diluted H2SO4 solution was used to dissolve Polyaniline in order to obtain a solution for preparation of thin films by spin coating technique. The chemical bonding characteristics of the prepared films were investigated using Furrier transform infrared spectroscopy (FTIR) and the structural characterizations were accomplished by X-ray diffraction (XRD). UV-VIS absorption spectroscopy was used to determine the optical band gap of the deposited PANi films and the indirect optical band gap of PANi was estimated to be in the range of 1.3 to 1.8 eV from the Tauc's plot. Further, these films were deposited on the n-MoSe2 crystal in order to complete a solar cell structure. The polychromatic photo response of the prepared solar cells for different intensities was studied at room temperature and the efficiency and fill factor were found to be 1% and 0.26 respectively. The obtained Photo-conversion characteristics (I-V) were also used to determined series and shunt resistances of the prepared device. The series resistance was found to be around 33.3 kΩ which is quite high. This may be a reason for such a low efficiency of this cell.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Design, fabrication and optical characterization of photonic crystal assisted thin film monocrystalline-silicon solar cells.

    PubMed

    Meng, Xianqin; Depauw, Valérie; Gomard, Guillaume; El Daif, Ounsi; Trompoukis, Christos; Drouard, Emmanuel; Jamois, Cécile; Fave, Alain; Dross, Frédéric; Gordon, Ivan; Seassal, Christian

    2012-07-02

    In this paper, we present the integration of an absorbing photonic crystal within a monocrystalline silicon thin film photovoltaic stack fabricated without epitaxy. Finite difference time domain optical simulations are performed in order to design one- and two-dimensional photonic crystals to assist crystalline silicon solar cells. The simulations show that the 1D and 2D patterned solar cell stacks would have an increased integrated absorption in the crystalline silicon layer would increase of respectively 38% and 50%, when compared to a similar but unpatterned stack, in the whole wavelength range between 300 nm and 1100 nm. In order to fabricate such patterned stacks, we developed an effective set of processes based on laser holographic lithography, reactive ion etching and inductively coupled plasma etching. Optical measurements performed on the patterned stacks highlight the significant absorption increase achieved in the whole wavelength range of interest, as expected by simulation. Moreover, we show that with this design, the angle of incidence has almost no influence on the absorption for angles as high as around 60°.

  10. Electroless (autocatalytic) nickel-cobalt thin films as solar control coatings

    SciTech Connect

    John, S.; Srinivasan, K.N.; Selvam, M.; Anuradha, S.; Rajendran, S.

    1994-12-31

    This paper describes the deposition of nickel-cobalt-phosphorus coatings by the electroless deposition technique for use as solar control coatings in architectural glazing of buildings. Electroless deposition is characterized by the autocatalytic deposition of a metal/alloy from an aqueous solution of its ions by interaction with a chemical reducing agent. The reducing agent provides electrons for the metal ions to be neutralized. The reduction is initiated by the catalyzed surface of the substrate and continued by the self catalytic activity of the deposited metal/alloy as long as the substrate is immersed in the electroless bath and operating conditions are maintained. Electroless nickel-cobalt-phosphorus thin films were deposited from a solution containing 15 g/l nickel sulphate, 5 g/l cobalt sulphate, 60 g/l ammonium citrate and 25 g/l sodium hypophosphite operating at 30 C, at a pH of 9.5 for two minutes. Electroless nickel-cobalt-phosphorus coatings are found to satisfy the basic requirements of solar control coatings. Autocatalytic deposition technique offers the possibilities of producing large area coatings with low capital investment, stability and good adhesion to glass substrates.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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%.

  16. a-Si{sub x}C{sub 1−x}:H thin films with subnanometer surface roughness for biological applications

    SciTech Connect

    Herrera-Celis, José Reyes-Betanzo, Claudia Itzmoyotl-Toxqui, Adrián; Orduña-Díaz, Abdu Pérez-Coyotl, Ana

    2015-09-15

    The characterization of a-Si{sub x}C{sub 1−x}:H thin films by plasma-enhanced chemical vapor deposition with high hydrogen dilution for biological applications is addressed. A root mean square roughness less than 1 nm was measured via atomic force microscopy for an area of 25 μm{sup 2}. Structural analysis was done using Fourier transform infrared spectroscopy in the middle infrared region. It was found that under the deposition conditions, the formation of Si–C bonds is promoted. Electrical dark conductivity measurements were performed to evaluate the effect of high hydrogen dilution and to find the relation between carrier transport properties and the structural arrangement. Conductivities of the order of 10{sup −7} to 10{sup −9} S/cm at room temperature for methane–silane gas flow ratio from 0.35 to 0.85 were achieved, respectively. UV-visible spectra were used to obtain the optical band gap and the Tauc parameter. Optical band gap as wide as 3.55 eV was achieved in the regime of high carbon incorporation. Accordingly, deposition under low power density and high hydrogen dilution reduces the roughness, improves the structure of the network, and stabilizes the film properties as a greater percentage of carbon is incorporated. The biofunctionalization of a-Si{sub x}C{sub 1−x}:H surfaces with NH{sub 2}-terminated self-assembled monolayers was obtained through silanization with 3-aminopropyltrimethoxysilane. This knowledge opens a window for the inclusion of these a-Si{sub x}C{sub 1−x}:H thin films in devices such as biosensors.

  17. Indium tin oxide subwavelength nanostructures with surface antireflection and superhydrophilicity for high-efficiency Si-based thin film solar cells.

    PubMed

    Leem, Jung Woo; Yu, Jae Su

    2012-05-07

    We fabricated the parabola-shaped subwavelength grating (SWG) nanostructures on indium tin oxide (ITO) films/Si and glass substrates using laser interference lithography, dry etching, and subsequent re-sputtering processes. The efficiency enhancement of an a-Si:H/μc-Si:H tandem thin film solar cell was demonstrated theoretically by applying the experimentally measured data of the fabricated samples to the simulation parameters. Their wetting behaviors and effective electrical properties as well as optical reflectance properties of ITO SWGs, together with theoretical prediction using a rigorous coupled-wave analysis method, were investigated. For the parabola-shaped ITO SWG/ITO film, the solar weighted reflectance (SWR) value was ~10.2% which was much lower than that (i.e., SWR~20%) of the conventional ITO film, maintaining the SWR values less than 19% up to a high incident angle of 70° over a wide wavelength range of 300-1100 nm. Also, the ITO SWG with a superhydrophilic surface property (i.e., water contact angle of 6.2°) exhibited an effective resistivity of 2.07 × 10(-3) Ω-cm. For the a-Si:H/μc-Si:H tandem thin film solar cell structure incorporated with the parabola-shaped ITO SWG/ITO film as an antireflective electrode layer, the conversion efficiency (η) of 13.7% was theoretically obtained under AM1.5g illumination, indicating an increased efficiency by 1.4% compared to the device with the conventional ITO film (i.e., η = 12.3%).

  18. 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

  19. 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.

  20. A study of the applicability of ZnO thin-films as anti-reflection coating on Cu{sub 2}ZnSnS{sub 4} thin-films solar cell

    SciTech Connect

    Ray, Abhijit; Patel, Malkeshkumar; Tripathi, Brijesh; Kumar, Manoj

    2012-06-25

    Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF{sub 2}. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

  1. Half-Corbino short-channel amorphous In-Ga-Zn-O thin-film transistors with a-SiOx or a-SiOx/a-SiNx passivation layers

    NASA Astrophysics Data System (ADS)

    Zhao, Chumin; Fung, Tze-Ching; Kanicki, Jerzy

    2016-06-01

    We investigated the electrical properties and stability of short-channel half-Corbino amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). In the linear region, the fabricated half-Corbino a-IGZO TFT with a channel length of 4.5 μm achieves a geometrical factor (fg) of ∼2.7, a threshold voltage (VT) of ∼2.4 V, a field-effect mobility (μeff) of ∼15 cm2/Vs, a subthreshold swing (SS) of ∼320 mV/dec and an off-current (IOFF) < 10-13 A. In the saturation region, asymmetric electrical characteristics such as drain current were observed under different drain bias conditions. The electrical properties asymmetry of half-Corbino a-IGZO TFTs was explained by various geometrical factors owing to the short-channel effect. The reduced VT and increased SS at VDS = 15 V is explained by the drain-induced Schottky barrier lowering. In addition, the bias-temperature stress (BTS) was performed for half-Corbino a-IGZO TFTs with both amorphous silicon oxide (a-SiOx) single layer and a-SiOx/amorphous silicon nitride (a-SiNx) bilayer passivation (PV) structures. The device with bilayer PV shows a threshold voltage shift (ΔVT) of +2.07 and -0.5 V under positive (PBTS = +15 V) and negative BTS (NBTS = -15 V) at 70 °C for 10 ks, respectively. The origins of ΔVT during PBTS and NBTS for half-Corbino a-IGZO TFTs with single and bilayer PV structures were studied. To improve the device electrical stability, the bilayer PV structure should be used.

  2. 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%.

  3. High-Performance and Omnidirectional Thin-Film Amorphous Silicon Solar Cell Modules Achieved by 3D Geometry Design.

    PubMed

    Yu, Dongliang; Yin, Min; Lu, Linfeng; Zhang, Hanzhong; Chen, Xiaoyuan; Zhu, Xufei; Che, Jianfei; Li, Dongdong

    2015-11-01

    High-performance thin-film hydrogenated amorphous silicon solar cells are achieved by combining macroscale 3D tubular substrates and nanoscaled 3D cone-like antireflective films. The tubular geometry delivers a series of advantages for large-scale deployment of photovoltaics, such as omnidirectional performance, easier encapsulation, decreased wind resistance, and easy integration with a second device inside the glass tube. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Optimization of Processing and Modeling Issues for Thin Film Solar Cell Devices: Final Report, 24 August 1998-23 October 2001

    SciTech Connect

    Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Eser, E.; Hegedus, S. S.; McCandless, B. E.; Aparicio, R.; Dobson, K.

    2003-01-01

    This report describes results achieved during a three-year subcontract to develop and understand thin-film solar cell technology associated to CuInSe2 and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE 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 of improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to illumination, temperature, and ambient and with respect to device structure and module encapsulation.

  5. Optimization of Processing and Modeling Issues for Thin-Film Solar Cell Devices; Annual Report, 3 February 1997-2 February 1998

    SciTech Connect

    Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Hegedus, S. S.; McCandless, B. E.

    1998-12-08

    This report describes results achieved during phase I of a four-phase subcontract to develop and understand thin-film solar cell technology associated with CuInSe2 and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE 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 developing 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 of improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to illumination, temperature, and ambient and with respect to device structure and module encapsulation.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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)

  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. Multi-frequency EDMR applied to microcrystalline thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Meier, Christoph; Behrends, Jan; Teutloff, Christian; Astakhov, Oleksandr; Schnegg, Alexander; Lips, Klaus; Bittl, Robert

    2013-09-01

    Pulsed multi-frequency electrically detected magnetic resonance (EDMR) at X-, Q- and W-Band (9.7, 34, and 94 GHz) was applied to investigate paramagnetic centers in microcrystalline silicon thin-film solar cells under illumination. The EDMR spectra are decomposed into resonances of conduction band tail states (e states) and phosphorus donor states (P states) from the amorphous layer and localized states near the conduction band (CE states) in the microcrystalline layer. The e resonance has a symmetric profile at all three frequencies, whereas the CE resonance reveals an asymmetry especially at W-band. This is suggested to be due to a size distribution of Si crystallites in the microcrystalline material. A gain in spectral resolution for the e and CE resonances at high fields and frequencies demonstrates the advantages of high-field EDMR for investigating devices of disordered Si. The microwave frequency independence of the EDMR spectra indicates that a spin-dependent process independent of thermal spin-polarization is responsible for the EDMR signals observed at X-, Q- and W-band.

  13. Multi-frequency EDMR applied to microcrystalline thin-film silicon solar cells.

    PubMed

    Meier, Christoph; Behrends, Jan; Teutloff, Christian; Astakhov, Oleksandr; Schnegg, Alexander; Lips, Klaus; Bittl, Robert

    2013-09-01

    Pulsed multi-frequency electrically detected magnetic resonance (EDMR) at X-, Q- and W-Band (9.7, 34, and 94GHz) was applied to investigate paramagnetic centers in microcrystalline silicon thin-film solar cells under illumination. The EDMR spectra are decomposed into resonances of conduction band tail states (e states) and phosphorus donor states (P states) from the amorphous layer and localized states near the conduction band (CE states) in the microcrystalline layer. The e resonance has a symmetric profile at all three frequencies, whereas the CE resonance reveals an asymmetry especially at W-band. This is suggested to be due to a size distribution of Si crystallites in the microcrystalline material. A gain in spectral resolution for the e and CE resonances at high fields and frequencies demonstrates the advantages of high-field EDMR for investigating devices of disordered Si. The microwave frequency independence of the EDMR spectra indicates that a spin-dependent process independent of thermal spin-polarization is responsible for the EDMR signals observed at X-, Q- and W-band. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. POLYCRYSTALLINE THIN FILM SOLAR CELLS:Present Status and Future Potential

    NASA Astrophysics Data System (ADS)

    Birkmire, Robert W.; Eser, Erten

    1997-08-01

    Polycrystalline thin film solar cells on copper indium diselenide (CulnSe2) and its alloys and cadmium telluride (CdTe) appear to be the most promising candidates for large-scale application of photovoltaic energy conversion because they have shown laboratory-efficiences in excess of 15%. Heterojunction devices with n-type cadmium sulfide (CdS) films show very low minority carrier recombination at the absorber grain boundaries and at the metallurgical interface, which results in high quantum efficiences. Open circuit voltages of these devices are relatively low owing to the recombination in the space charge region in the absorber. Further improvements in efficiency can be achieved by reducing the recombination current, especially in devices based on CulnSe2 and its alloys. Low-cost manufacturing of modules requires better resolution of a number of other technical issues. For modules based on CulnSe2 and its alloys, the role of Na and higher deposition rates on device performance need to be better understood. In addition, replacing the chemical bath deposition method for CdS film deposition with an equally effective, but more environmentally acceptable process is needed. For modules based on CdTe, more fundamental understanding of the effect of chloride/oxygen treatment and the development of more reproducible and manufacturable CdTe contacting schemes are necessary.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.