13% Silicon FilmTM solar cells on low-cost barrier-coated substrates

Thin-film polycrystalline silicon solar cells offer significant cost savings over single crystal and cast polycrystalline wafers that are sliced from ingots, and they are more stable than amorphous silicon solar cells which suffer from photo-induced degradation. A new barrier layer and low cost substrate that meet the criteria for thin films of polycrystalline silicon to be grown using the Silicon Film^TM process has been developed. Films grown on this new barrier/substrate combination have exhibited minority carrier diffusion lengths as high as 250 μm when external phosphorous gettering is employed. Using conventional silicon processing technologies, with special provision made for electrical connection to the base layer, an efficiency of 13.8% has been measured in a 0.46 cm² thin-film polycrystalline silicon solar cell grown on this new barrier-coated substrate. Technical details of the development are presented in this paper