Toward Efficient Thin-Film Polycrystalline-Silicon Modules using Interdigitated Top Contacts

Efficient thin-film polycrystalline-silicon (pc-Si) modules on inexpensive substrates could substantially lower the price of photovoltaic electricity. To obtain efficient pc-Si modules, processes different from those applied for standard bulk-Si solar cells have to be developed. In this paper we report on a monolithic module process for thin-film pc-Si solar cells in substrate configuration. In this process all contacts are made on top of the cells in an interdigitated pattern. Individual pc-Si cells with interdigitated top contacts showed very good fill factors up to 75% in combination with Voc values well above 500 mV. First module tests showed that cell isolation is the most crucial step to obtain properly working pc-Si modules using our process. These results indicate that a module concept based on interdigitated top contacts could lead to highly efficient pc-Si modules.