SILICON SOLAR-CELL OF 16.8 MU-M THICKNESS AND 14.7-PERCENT EFFICIENCY

Liquid phase epitaxy provides a new impetus for thin film photovoltaics based on silicon; we apply this method for about 20-mum-thick solar cells with high efficiencies. The analysis of internal quantum efficiency measurements reveals that the open circuit voltages around 660 mV arise from an excellent electronic quality of our thin silicon films. Their effective minority carrier diffusion lengths range up to 317 mum, a value that exceeds the thickness of the layers by an order of magnitude. The conversion efficiencies exceed 14% with a record value of 14.7% for a 16.8-mum-thick epitaxial layer without special antireflecting coatings. The high open circuit voltages promise a possible boost of the efficiency toward 20% by applying light trapping schemes to optimize the short circuit current.