8% Efficient thin‐film polycrystalline‐silicon solar cells based on aluminum‐ induced crystallization and thermal CVD

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.

Influence of Hydrogen Plasma on the Defect Passivation of Polycrystalline Si Thin Film Solar Cells

“…[8][9][10][11] An approach where the deposition is done at temperatures of about 1100 8C shows promising results, but requires substrates capable of withstanding these temperatures. [12] Processes using lower deposition temperatures are attractive since they are compatible with the usage of glass substrates. The most prominent low temperature technique is based on solid phase crystallization (SPC) of amorphous Si films that are deposited by either chemical (CVD) [7] or physical vapour deposition (PVD) processes.…”

High-mobility pentacene phototransistor with nanostructured SiO2 gate dielectric synthesized by sol–gel method

“…Rech et al showed that ZnO:Al films prepared by magnetron sputtering and post deposition wet chemical etching demonstrate an effective light trapping and the textured surface reduces reflection losses at the ZnO:Al/Si-interface with excellent light scattering properties for silicon thin film solar cells and modules [3,4]. Grained polycrystalline silicon (poly-Si) films were prepared on nano-textured glass substrates by epitaxial thickening of seed layers formed by the aluminum-induced layer exchange (ALILE) process [5,6] for poly-Si thin film solar cell application with 8% efficiencies with improved material quality [7][8][9][10].…”

Thin film pc-Si by aluminium induced crystallization on metallic substrate

“…Large grains p-type pc-Si can be obtained by aluminum induced crystallization (AIC) [7]. Thin-film polycrystalline-silicon solar cells based on AIC and thermal CVD with 8% efficiency has already been reported on alumina substrate [8].…”