THIN-FILM POLYCRYSTALLINE-SILICON SOLAR CELLS ON HIGH-TEMPERATURE SUBSTRATES BY ALUMINIUM-INDUCED CRYSTALLIZATION

摘要

A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from thin polycrystalline-silicon (pc-Si) layers on inexpensive substrates. Aluminum-induced crystallization (AIC) of amorphous silicon followed by epitaxial thickening is an effective way to obtain large-grained pc-Si layers with excellent properties for solar cells. To obtain efficient solar cells, the cell design has to be adapted to the material. In this paper, we report on pc-Si solar cells made by AIC in combination with thermal CVD on ceramic alumina and on glass-ceramic substrates. We show that pc-Si cells with V_(oc) values up to 539 mV and fill factors above 70% can be made by the use of amorphous Si / crystalline Si heterojunctions and interdigitated top contacts. By using plasma texturing, we could enhance the current density of our cells. In this way, we reached a maximum cell efficiency of 7.0% on alumina. This is by far the highest efficiency ever achieved with pc-Si solar cells on ceramic substrates where no (re)melting of silicon was used. These results indicate the large potential of pc-Si solar cells based on AIC in combination with epitaxial growth.