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

Liquid phase epitaxy provides a new impetus for thin film photovoltaic s based on silicon; we apply this method for about 20-mum-thick solar cells with high efficiencies. The analysis of internal quantum efficie ncy 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 magn itude. The conversion efficiencies exceed 14% with a record value of 1 4.7% for a 16.8-mum-thick epitaxial layer without special antireflecti ng coatings. The high open circuit voltages promise a possible boost o f the efficiency toward 20% by applying light trapping schemes to opti mize the short circuit current.