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 SiN_x anti-reflective coating. Thermally-grown SiO₂ was applied as the front surface passivation of industrial Si solar cells with high sheet-resistivity (115 Ω/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 ~18 nm thick SiO₂ grown at 850 °C over the industrial-type reference cells.