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Absorber Layer (absorber + layer)
Selected AbstractsPhotovoltaic Devices: High-Efficiency Solar Cell with Earth-Abundant Liquid-Processed Absorber (Adv. Mater.ADVANCED MATERIALS, Issue 20 201020/2010) The image shows a thin-film solar cell, deposited from a hybrid solution-nanoparticle ink, with a background scanning electron microscopy (SEM) image of the zinc-compound particle component of the ink. A cross-sectional SEM image of the device shows the large-grained kesterite absorber layer composed of readily available elements: Cu-Zn-Sn-S-Se. The solution-processed devices offer record power conversion efficiency for kesterite absorber layers, as presented by D. B. Mitzi et al. on page E156. [source] Microcrystalline silicon n-i-p solar cells prepared with microcrystalline silicon oxide (,c-SiOx:H) n-layerPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010Vladimir Smirnov Abstract N-type hydrogenated microcrystalline silicon oxide (,c-SiOx:H) layers were used as window layers in n-side illuminated microcrystalline silicon n,i,p solar cells. Optical, electrical and structural properties of ,c-SiOx:H films were investigated by Photothermal Deflection Spectroscopy, conductivity and Raman scattering measurements. ,c-SiOx:H layers were prepared over a range of carbon dioxide (CO2) flow and film thickness, and the effects on the solar cell performance were investigated. By optimising the ,c-SiOx:H window layer properties, an improved short-circuit current density of 23.4 mA/cm2 is achieved, leading to an efficiency of 8.0% for 1,m thick absorber layer and Ag back contact. The correlation between cell performance and ,c-SiOx:H layer properties is discussed. The results are compared to the performance of solar cells prepared with alternative optimised window layers. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Admittance spectroscopy defect density of electrodeposited CuIn(S,Se)2 and its correlation with solar cells performancesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2008A. Darga Abstract Electrodeposited CuIn(S,Se)2 based solar cells with varying CdS buffer layer thicknesses were studied by admittance spectroscopy. An electrically active defect was identified. Its density of states which varies with CdS layer deposition process was found to be correlated with solar cell performance. This defect seems to be CdS/CuIn(S,Se)2 interface defect or to be located within the grain boundaries of the absorber layer. Direct dark I,V measurements reveal that the dominant recombination mechanism is a tunnelling assisted process. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] TCOs for nip thin film silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2009T. Söderström Abstract Substrate configuration allows for the deposition of thin film silicon (Si) solar cells on non-transparent substrates such as plastic sheets or metallic foils. In this work, we develop processes compatible with low Tg plastics. The amorphous Si (a-Si:H) and microcrystalline Si (µc-Si:H) films are deposited by plasma enhanced chemical vapour deposition, at very high excitation frequencies (VHF-PECVD). We investigate the optical behaviour of single and triple junction devices prepared with different back and front contacts. The back contact consists either of a 2D periodic grid with moderate slope, or of low pressure CVD (LP-CVD) ZnO with random pyramids of various sizes. The front contacts are either a 70,nm thick, nominally flat ITO or a rough 2,µm thick LP-CVD ZnO. We observe that, for a-Si:H, the cell performance depends critically on the combination of thin flat or thick rough front TCOs and the back contact. Indeed, for a-Si:H, a thick LP-CVD ZnO front contact provides more light trapping on the 2D periodic substrate. Then, we investigate the influence of the thick and thin TCOs in conjunction with thick absorbers (µc-Si:H). Because of the different nature of the optical systems (thick against thin absorber layer), the antireflection effect of ITO becomes more effective and the structure with the flat TCO provides as much light trapping as the rough LP-CVD ZnO. Finally, the conformality of the layers is investigated and guidelines are given to understand the effectiveness of the light trapping in devices deposited on periodic gratings. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-efficiency µc-Si solar cells made by very high-frequency plasma-enhanced chemical vapor depositionPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 4 2006A. Gordijn Abstract Microcrystalline silicon-based single-junction p,i,n solar cells have been fabricated by very high-frequency plasma enhanced chemical vapor deposition using a showerhead cathode at high pressures and under silane depletion conditions. The i -layers are made near the transition from amorphous to crystalline. It was found that, especially at high crystalline fractions, the open-circuit voltage and fill factor are very sensitive to the morphology of the substrate. At an i -layer deposition rate 0·45,nm/s, we have measured a stabilised efficiency of 10% (Voc,=,0·52,V, FF,=,0·74) for a cell made on texture-etched ZnO:Al. The performance is stable under light soaking. The defect density of the absorber layer is in the 1015,cm,3 range. In spite of the presence of oxygen contamination, good electrical properties and good infrared cell response are obtained. Copyright © 2006 John Wiley & Sons, Ltd. [source] Comparison of device performance and measured transport parameters in widely-varying Cu(In,Ga) (Se,S) solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2006I. L. Repins Abstract We report the results of an extensive study employing numerous methods to characterize carrier transport within copper indium gallium sulfoselenide (CIGSS) photovoltaic devices, whose absorber layers were fabricated by diverse process methods in multiple laboratories. This collection of samples exhibits a wide variation of morphologies, compositions, and solar power conversion efficiencies. An extensive characterization of transport properties is reported here,including those derived from capacitance,voltage, admittance spectroscopy, deep level transient spectroscopy, time-resolved photoluminescence, Auger emission profiling, Hall effect, and drive level capacitance profiling. Data from each technique were examined for correlation with device performance, and those providing indicators of related properties were compared to determine which techniques and interpretations provide credible values for transport properties. Although these transport properties are not sufficient to predict all aspects of current-voltage characteristics, we have identified specific physical and transport characterization methods that can be combined using a model-based analysis algorithm to provide a quantitative prediction of voltage loss within the absorber. The approach has potential as a tool to optimize and understand device performance irrespective of the specific process used to fabricate the CIGSS absorber layer. Copyright © 2005 John Wiley & Sons, Ltd. [source] The effect of oxygen on interface microstructure evolution in CdS/CdTe solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2002D.S. Albin Microstructural changes at the CdS/CdTe solar cell interface where close-spaced sublimation (CSS) is used as the growth technique to deposit the p -type CdTe absorber layer are studied by systematic layer characterization at various stages during heterojunction growth. CdS layers grown by both chemical bath deposition (CBD) and CSS provide a basis for determining the effects of CdS crystallinity, grain size, and oxygen content on the subsequent CdTe layer. As-grown CBD CdS films exhibit small grains and variations in optical properties attributed to film impurities. In contrast, CSS yields CdS films with good crystallinity, larger grains, and nearly ideal optical properties. The hexagonal nature of CSS-grown CdS is seen to nucleate hexagonal CdTe during the initial stages of CdTe film growth. Cubic CdS deposited by CBD in contrast promotes cubic CdTe nucleation. Oxygen anneals in the latter case can aid hexagonal CdTe nucleation. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) of the CdS/CdTe interface show CdS-dependent differences in interdiffusion at the interface. This interdiffusion appears to be determined by the oxygen level in the CdS. When low-oxygen-containing CSS CdS films are used, sulfur diffusion is substantial, leading to significant consumption of the CdS layer. When these same films are annealed in oxygen, the consumption is reduced. Te diffusion into the CdS layer is also observed to decrease with oxygen anneals. Optical modeling shows that Te alloying with the CdS layer can greatly reduce the short-circuit current of CdS/CdTe devices. Copyright © 2002 John Wiley & Sons, Ltd. [source] Ternary single-source precursors for polycrystalline thin-film solar cellsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2002Kulbinder K. Banger The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution for fabricating solar arrays with high specific power (W kg,1). The use of a polycrystalline chalcopyrite absorber layer for thin-film solar cells is considered as the next generation in photovoltaic devices. At NASA GRC we have focused on the development of new single-source precursors (SSPs) and their utility to deposit the chalcopyrite semiconducting layer (CIS) onto flexible substrates for solar-cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering are described. Thin-film fabrication studies demonstrate that the SSPs can be used in a spray chemical vapor deposition process for depositing CIS at reduced temperatures, and result in electrical properties that are suitable for photovoltaic devices. Copyright © 2002 John Wiley & Sons, Ltd. [source] Photovoltaic Devices: High-Efficiency Solar Cell with Earth-Abundant Liquid-Processed Absorber (Adv. Mater.ADVANCED MATERIALS, Issue 20 201020/2010) The image shows a thin-film solar cell, deposited from a hybrid solution-nanoparticle ink, with a background scanning electron microscopy (SEM) image of the zinc-compound particle component of the ink. A cross-sectional SEM image of the device shows the large-grained kesterite absorber layer composed of readily available elements: Cu-Zn-Sn-S-Se. The solution-processed devices offer record power conversion efficiency for kesterite absorber layers, as presented by D. B. Mitzi et al. on page E156. [source] Pyroelectric coupling in thin film photovoltaicsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 4 2007Victor G. Karpov Abstract We propose a theory of thin film photovoltaics in which one of the polycrystalline films is made of a pyroelectric material grains such as CdS. That film is shown to generate strong polarization improving the device open circuit voltage. Implications and supporting facts for the major photovoltaic types based on CdTe and CuIn(Ga)Se2 absorber layers are discussed. Band diagram of a pyroelectric (CdS) based PV junction. Arrows represent the charge carrier photo-generation. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High potential of thin (<1,µm) a-Si: H/µc-Si:H tandem solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2010S. Schicho Abstract Silicon based thin tandem solar cells were fabricated by plasma enhanced chemical vapor deposition (PECVD) in a 30,×,30,cm2 reactor. The layer thicknesses of the amorphous top cells and the microcrystalline bottom cells were significantly reduced compared to standard tandem cells that are optimized for high efficiency (typically with a total absorber layer thickness from 1.5 to 3,µm). The individual absorber layer thicknesses of the top and bottom cells were chosen so that the generated current densities are similar to each other. With such thin cells, having a total absorber layer thickness varying from 0.5 to 1.5,µm, initial efficiencies of 8.6,10.7% were achieved. The effects of thickness variations of both absorber layers on the device properties have been separately investigated. With the help of quantum efficiency (QE) measurements, we could demonstrate that by reducing the bottom cell thickness the top cell current density increased which is addressed to back-reflected light. Due to a very thin a-Si:H top cell, the thin tandem cells show a much lower degradation rate under continuous illumination at open circuit conditions compared to standard tandem and a-Si:H single junction cells. We demonstrate that thin tandem cells of around 550,nm show better stabilized efficiencies than a-Si:H and µc-Si:H single junction cells of comparable thickness. The results show the high potential of thin a-Si/µc-Si tandem cells for cost-effective photovoltaics. Copyright © 2010 John Wiley & Sons, Ltd. [source] 8% Efficient thin-film polycrystalline-silicon solar cells based on aluminum- induced crystallization and thermal CVDPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2007I. Gordon Abstract A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline-silicon (pc-Si) thin films on inexpensive substrates. We recently showed promising solar cell results using pc-Si layers obtained by aluminum-induced crystallization (AIC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc-Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk-Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc-Si solar cells on alumina substrates made by AIC in combination with thermal CVD. Our present pc-Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 8·0%. Spin-on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a-Si layers that yield much higher Voc values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc-Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc-Si solar cells based on the AIC seed layer approach. Copyright © 2007 John Wiley & Sons, Ltd. [source] Optical properties of thin-film silicon solar cells with grating couplersPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2006C. Haase Abstract The effect of grating couplers on the optical properties of silicon thin-film solar cells was studied by a comparison of experimental results with numerical simulations. The thin-film solar cells studied are based on microcrystalline silicon (,c-Si:H) absorber layers of thickness in the micrometer range. To investigate the light propagation in these cells, especially in the red wavelength region, three-dimensional power loss profiles are simulated. The influence of different grating parametres,such as period size, groove height, and shape of the grating,was studied to gain more insight into the light propagation within thin-film silicon solar cells and to determine an optimized light trapping scheme. The effect of the TCO front and TCO back side layer thickness was investigated. The calculated quantum efficiencies and short-circuit current densities are in good agreement with the experimental data. The simulations predict further optimization criteria. Copyright © 2006 John Wiley & Sons, Ltd. [source] Comparison of device performance and measured transport parameters in widely-varying Cu(In,Ga) (Se,S) solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2006I. L. Repins Abstract We report the results of an extensive study employing numerous methods to characterize carrier transport within copper indium gallium sulfoselenide (CIGSS) photovoltaic devices, whose absorber layers were fabricated by diverse process methods in multiple laboratories. This collection of samples exhibits a wide variation of morphologies, compositions, and solar power conversion efficiencies. An extensive characterization of transport properties is reported here,including those derived from capacitance,voltage, admittance spectroscopy, deep level transient spectroscopy, time-resolved photoluminescence, Auger emission profiling, Hall effect, and drive level capacitance profiling. Data from each technique were examined for correlation with device performance, and those providing indicators of related properties were compared to determine which techniques and interpretations provide credible values for transport properties. Although these transport properties are not sufficient to predict all aspects of current-voltage characteristics, we have identified specific physical and transport characterization methods that can be combined using a model-based analysis algorithm to provide a quantitative prediction of voltage loss within the absorber. The approach has potential as a tool to optimize and understand device performance irrespective of the specific process used to fabricate the CIGSS absorber layer. Copyright © 2005 John Wiley & Sons, Ltd. [source] Development of thin-film Cu(In,Ga)Se2 and CdTe solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2-3 2004A. Romeo Abstract Cu(In,Ga)Se2 and CdTe heterojunction solar cells grown on rigid (glass) or flexible foil substrates require p -type absorber layers of optimum optoelectronic properties and n -type wide-bandgap partner layers to form the p,n junction. Transparent conducting oxide and specific metal layers are used for front and back electrical contacts. Efficiencies of solar cells depend on various deposition methods as they control the optoelectronic properties of the layers and interfaces. Certain treatments, such as addition of Na in Cu(In,Ga)Se2 and CdCl2 treatment of CdTe have a direct influence on the electronic properties of the absorber layers and efficiency of solar cells. Processes for the development of superstrate and substrate solar cells are reviewed. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||