Optical Transparency and Surface Recombination Considerations for High Sheet Resistance Emitter Passivation on Silicon Solar Cells

The optical impacts of thin SiO2 passivation layer on industrial Si solar cells are modeled. The modeling shows that negligible optical loss results from SiO2 of <18 nm thickness in combination with an adjusted thickness of conventional SiNx anti-reflective coating. Thermally-grown SiO2 was applied as the front surface passivation of industrial Si solar cells with high sheet-resistivity (115 Omega/sq) emitter. Considerable improvement was observed in effective minority carrier lifetime, and 9 mV of Voc and 0.1% ( absolute) of cell efficiency gains have been attained with similar to 18 nm thick SiO2 grown at 850 degrees C over the industrial-type reference cells.