Showing papers on "Polymer solar cell published in 1997"
TL;DR: Porous silicon was formed on mono- and multicrystalline Si substrates by stain etching in aqueous HF/HNO3 solutions as discussed by the authors, which was investigated by reflectance spectroscopy and related to the main etch parameters.
81 citations
TL;DR: The performance improvement of solar cells due to the formation of a porous silicon layer on deep-junction n+/p silicon structures has been investigated in this paper, where the photovoltaic properties of two identical sample groups with and without porous silicon layers are compared.
72 citations
TL;DR: Shallow junction multicrystalline Si solar cells have been processed by an anodical etching technique and more than 25% improvement in short-circuit current and photovoltaic energy conversion efficiency was demonstrated.
65 citations
TL;DR: In this paper, the performance of the AlGaAs Si tandem solar cells was evaluated by time resolved photoluminescence and double crystal X-ray diffraction while varying the thermal cycle annealing temperature.
58 citations
TL;DR: In this article, the authors proposed a new cell design that utilizes submicron thin silicon layers to compensate for low minority carrier diffusion lengths, which exhibits excellent light trapping properties and allows for 10% efficiency at an optimum cell thickness of 0.4 μm only.
Abstract: We fabricate thin crystalline silicon solar cells with a minority carrier diffusion length of 0.6±0.2 μm by direct high-temperature chemical vapor deposition on glass substrates. This small diffusion length does not allow high cell efficiencies with conventional cell designs. We propose a new cell design that utilizes submicron thin silicon layers to compensate for low minority carrier diffusion lengths. According to theoretical modeling, our design exhibits excellent light trapping properties and allows for 10% efficiency at an optimum cell thickness of 0.4 μm only. This submicron range of cell thicknesses was formerly thought to require direct band gap semiconductors.
57 citations
Proceedings Article•
29 Sep 1997
TL;DR: In this article, the growth of CuIn3Se5 layer on bulk CuInSe2 films has been studied for the fabrication of In2Se2 solar cells, using the three-stage process which involved the sequential evaporation of In-, Se, and In-Se elemental sources.
Abstract: Abstract The growth of CuIn3Se5 layer on bulk CuInSe2 films has been studied for the fabrication of CuInSe2 solar cells, using the three-stage process which involved the sequential evaporation of In–Se, Cu–Se, and In–Se elemental sources. After growing CuInSe2 films, the film surface was converted to a defect chalcopyrite (CuIn3Se5) compound. The X-ray diffraction and AES depth analysis indicated the formation of the CuIn3Se5 phase on the CuInSe2 surface. By the formation of the CuIn3Se5 phase, the absorption edge was shifted from 1200 to 1000 nm wavelength and the binding energies of Cu, In, and Se were shifted to higher energies. The current–voltage curves of In2Se3/CuInSe2 cells fabricated with a thick CuIn3Se5 layer on a CuInSe2 film displayed a kink effect which was possibly caused by the increase of series resistance and light absorption in the CuIn3Se5 layer instead of the junction region. The cells with a thin CuIn3Se5 layer at the In2Se3/CuInSe2 interface yielded solar efficiency of 8.46% with an active area of 0.2 cm2.
56 citations
TL;DR: In this paper, the properties of thin boron doped microcrystalline silicon layers deposited by PECVD on crystalline silicon wafers and on amorphous silicon buffer layers were studied by Raman spectroscopy and electro-optical characterization.
Abstract: We have studied by Raman spectroscopy and electro-optical characterization the properties of thin boron doped microcrystalline silicon layers deposited by plasma enhanced chemical vapor deposition (PECVD) on crystalline silicon wafers and on amorphous silicon buffer layers. Thin 20–30 nm p+ μc-Si:H layers with a considerably large crystalline volume fraction (∼22%) and good window properties were deposited on crystalline silicon under moderate PECVD conditions. The performance of heterojunction solar cells incorporating such window layers were critically dependent on the interface quality and the type of buffer layer used. A large improvement of open circuit voltage is observed in these solar cells when a thin 2–3 nm wide band-gap buffer layer of intrinsic a-Si:H deposited at low temperature (∼100 °C) is inserted between the microcrystalline and crystalline silicon [complete solar cell configuration: Al/(n)c-Si/buffer/p+μc-Si:H/ITO/Ag)]. Detailed modeling studies showed that the wide band-gap a-Si:H buffe...
52 citations
TL;DR: In this paper, the application of porous silicon (PS) as an antireflection coating material for commercial multicrystalline silicon solar cells was reported. But the application was restricted to the areas between the grid fingers without changing the front contact (selective PS formation).
48 citations
TL;DR: In this article, the authors studied light-induced degradation in hydrogenated and deuterated amorphous silicon alloy solar cells and showed that replacing hydrogen with deuterium in the intrinsic layer of the cell improves stability against light exposure.
Abstract: We have studied light-induced degradation in hydrogenated and deuterated amorphous silicon alloy solar cells. Replacing hydrogen with deuterium in the intrinsic layer of the cell improves stability against light exposure. Possible explanations for the improved stability are discussed.
48 citations
TL;DR: In this paper, the effects of sodium on off-stoichiometric Cu(In,Ga)Se2 (CIGS)-based thin films and solar cells were investigated.
48 citations
TL;DR: In this article, the authors demonstrate the fabrication of such micron-sized light traps by embossing of sol-gel glasses and demonstrate that the deposition of crystalline silicon layers of thickness, W = 4 μ m, on textured glass substrates doubles the cell current for facet angles and texture periods.
Abstract: An increase of light absorption by light trapping is a key issue for the design of thin film solar cells from crystalline silicon. According to our numerical work, the deposition of crystalline silicon layers of thickness, W = 4 μ m, on textured glass substrates doubles the cell current for facet angles, α = 75°, and texture periods p μ m, without the need for anti reflection coatings. We demonstrate the fabrication of such micron-sized light traps by embossing of sol—gel glasses.
TL;DR: In this article, the photovoltaic (PV) characteristics of both glow discharge deposited hydrogenated amorphous silicon (a-Si:H) on crystalline silicon (c-Si) in a n + a-Si h/undoped a-H/p c-Si type structure were investigated.
TL;DR: In this paper, the dependence of the solar cell parameters on the properties of the n-type a-Si:H layer is discussed and it is shown that this cell type exhibits no degradation under light exposure.
TL;DR: The quest for understanding and especially controlling the reversible light induced changes in a-Si:H-based materials has been ongoing for the last twenty years as discussed by the authors, with a corresponding large effort in minimizing their effects on more efficient aSi-H based solar cells.
Abstract: The quest for understanding and especially controlling the reversible light induced changes in a-Si:H based materials has been ongoing for the last twenty years. This has been accompanied by a corresponding large effort in minimizing their effects on more efficient a-Si:H based solar cells. Despite the complexities in both the phenomena as well as the solar cells, progress has been made in both the scientific and technological arenas. This paper briefly reviews primarily studies on the characterization and reduction of the metastable changes in materials and the correlation of these changes with those in efficient solar cells. It will discuss the impact of studies on materials as well as the continuous advances made with “engineering” of solar cell structures on their improved stabilized performance.
ENEA1
TL;DR: In this paper, the authors focus on the technology of the ITO front contact fabrication, that also is used as an antireflective coating, and show that this layer acts as a barrier layer against the diffusion of metal during the annealing treatments of the front contact grid.
31 Dec 1997
TL;DR: In this article, the authors proposed a collector structure with a high potential for thermal conversion efficiency while maintaining high electrical conversion efficiency for a-Si:H cells, with emphasis on a ZnO coat on top of the solar cell.
Abstract: Amorphous silicon (a-Si:H) based solar cells are highly interesting in the context of hybrid (i.e. photovoltaic/thermal) solar energy conversion. First, their large area capability and the variety of possible substrate materials permit to apply a-Si:H PV modules directly on the surface of conventional heat collectors at low cost. Further, the low temperature coefficient of a-Si:H cells (0.1%/K) allows operation of a-Si:H solar modules at temperatures as high as 100/spl deg/C without substantial power loss. The authors focus on the thermal performance of such hybrid collectors based on a-Si:H cells, with emphasis on a ZnO coat on top of the solar cell. ZnO can be "tuned" to absorb the infrared part of sunlight and, at the same time, its emission coefficient for heat-radiation is nearly as low as that of the optimized selective surfaces used in thermal collectors. The authors propose a collector structure with a high potential for thermal conversion efficiency while maintaining high electrical conversion efficiency.
TL;DR: In this paper, the authors review the principles and performance features of very efficient solar cells that are being developed in our laboratories based on the concept of dye-sensitization of wide bandgap semiconductors used in the form of mesoporous nanocrystalline membrane type films.
Abstract: The direct conversion of sunlight to electricity via photoelectrochemical solar cells is an attractive option that has been pursued for nearly two decades in several laboratories. In this paper, we review the principles and performance features of very efficient solar cells that are being developed in our laboratories. These are based on the concept of dye-sensitization of wide bandgap semiconductors used in the form of mesoporous nanocrystalline membrane-type films. The key feature is charge injection from the excited state of an anchored dye to the conduction band of an oxide semiconductor such as TiO2. In the use of the semiconductor in the form of high surface area, highly porous film offers several unique advantages: monomeric distribution of a large quantity of the dye in a compact (few micron thick) film, efficient charge collection and drastic inhibition of charge recombination (‘capture of charge carriers by oxidized dye’). Near quantitative efficiency for charge collection for monochromatic light excitation gives rise to sunlight conversion efficiency in the range of 8–10% This has led to fruitful collaboration with several industrial partners. Possible applications and commercialization of these solar cells and also other practical applications of nanosized films are briefly outlined.
TL;DR: In this article, the emitter geometry, front and rear contact size and pitch were optimized, and the cells were fabricated through a set of environmentally considered processes, especially for surface treatment, oxidation, diffusion, and electrode fabrication.
TL;DR: A photoelectrochemical solar cell from camphoric p-carbon semiconducting pellet has been developed for the first time from the soot of a natural source, camphor as discussed by the authors.
29 Sep 1997
TL;DR: In this article, a dry-chemical solar cell process was developed by substituting conventional wet etching steps by reactive ion etching, where graphite with two kinds of encapsulation have been used as a foreign substrate for the silicon deposition.
Abstract: A dry-chemical solar cell process has been developed by substituting conventional wet etching steps by reactive ion etching. The performance of mc-Si solar cells that have been made by this new technology is comparable to that of conventionally processed cells. Thin-film solar cells have been prepared by applying zone melting recrystallisation of CVD-grown, highly doped p/sup +/-Si layers, that were used as seeding layers for the growth of the active Si-layers. Graphite with two kinds of encapsulation have been used as a foreign substrate for the silicon deposition: (a) covered with conducting SiC, the graphite acts as base contact of the cells; and (b) graphite encapsulated with insulating SiC- and SiO/sub 2//SiN/SiO/sub 2/-layers (ONO) leads to solar cells on insulating foreign substrates, with front side base contact. The graphite/SiC/Si layer system was developed by ASE; ONO deposition and recrystallisation were realised at Fraunhofer ISE. Applying the authors' dry solar cell technology, conversion efficiencies up to 11% were achieved.
TL;DR: Amorphous diamond-like carbon films (a:DLC) were used as anti-reflecting coatings and as hard protecting materials for silicon solar cells as discussed by the authors, and a good correlation exists between the experimental and theoretical values.
TL;DR: In this paper, a planar junction amorphous and microcrystalline silicon-based thin-film solar cells with diffuse and selective angle rear reflectors were examined in detail, and it was shown that using a TiO2 diffuse reflector could increase the current of optically thin silicon solar cells beyond that possible using rough TCO/glass substrates.
TL;DR: In this paper, the back-surface recombination velocity (Sb) of multicrystalline silicon (mc-Si) was reduced from 10,000 to 2000 cm/s for 1 and 10 μm evaporated aluminum layers, respectively, alloyed in a conventional furnace.
01 Feb 1997
Abstract: Transparent conductors are needed as the front surface electrodes in all types of solar cells. The electrical and optical performance of a transparent conductor may be rated by a figure of merit defined as the ratio of the electrical conductivity to the optical absorption coefficient of the layer. Fluorine-doped zinc oxide is shown to have the highest figure of merit. ZnO:F films with a sheet resistance of 5 ohms per square can have a visible absorption of less than 3 per cent. This high performance makes zinc oxide a candidate for replacing tin oxide in thin film amorphous silicon solar cells, or for replacing part of the highly-doped silicon layer in crystalline silicon solar cells. A new, cost-effective process is described for the chemical vapor deposition of ZnO:F at atmospheric pressure.
29 Sep 1997
TL;DR: In this paper, the use of texture etched ZnO:Al films in amorphous silicon solar cells was investigated and the initial efficiencies were close to 10% for p-n and 8% for n-i-p solar cells.
Abstract: This paper treats the use of texture etched ZnO:Al films in amorphous silicon solar cells. Chemically textured ZnO:Al films were implemented as a front TCO in p-i-n (superstrate) and n-i-p (substrate) solar cells, and in combination with Ag as a textured back reflector in n-i-p (substrate) solar cells. These cells exhibit excellent optical and light-trapping properties demonstrated by high short-circuit current densities. Adapted microcrystalline p-layers solve the ZnO/p-contact problem and thereby provide high fill factors and open-circuit voltages. The initial efficiencies so far obtained are close to 10% for p-i-n and 8% for n-i-p solar cells.
TL;DR: In this paper, the performance of thin-films of CuInS2 solar cells was studied as a function of the H2 gas pressure during sulfurization, and the results showed that the conversion efficiency of the thinfilms was strongly affected by the reduction of the CuInO precursors.
TL;DR: Significant progress has recently been made in improving the stable efficiency of amorphous silicon alloy solar cells through a better understanding of the effect of plasma chemistry and growth kinetics on material characteristics and incorporation of the materials into an optimum device configuration.
Abstract: Significant progress has recently been made in improving the stable efficiency of amorphous silicon alloy solar cells. This has been achieved through a better understanding of the effect of plasma chemistry and growth kinetics on material characteristics and incorporation of the materials into an optimum device configuration.
TL;DR: In this article, a substantially simplified PERC silicon solar cell has been developed at ISFH with independently confirmed 1-sun efficiencies of up to 20.0% using a single phosphorous diffusion (1-step emitter).
TL;DR: In this article, two different applications of PS layers in the solar cell technology were demonstrated, and the increase of short-circuit current and efficiency by nearly 30% has been observed, which was explained by antireflective and surface passivating actions of the porous silicon layer.
Abstract: Two different applications of PS layers in the solar cell technology were demonstrated. In the first case, microporous layers, which are formed on silicon surface after relatively long anodical etching, roughen surface and enhance the optical confinement in the wafer increasing quantum efficiency in the spectral region close to 1 μm. Such a light-trapping effect was verified by spectral transmittivity and photoresponse measurements. In the second case, thin nanoporous layers formed by a short anodical treatment on already manufactured solar cells were investigated. The increase of the short-circuit current and efficiency by nearly 30% has been observed. Such an improvement was explained by antireflective and surface passivating actions of the porous silicon layer.
TL;DR: In this article, the feasibility of polycrystalline silicon (poly-Si) films deposited by catalytic CVD (cat-CVD) method as a solar cell material is studied.