Electrical and optical properties of thin film silicon solar cells with sub-wavelength surface structure and TiO2 passivation

This study presents the electrical and optical properties of a thin-film p-on-n silicon solar cell with a sub-wavelength nanoporous surface structure etched into the emitter layer using metal-assisted chemical etching (MACE) before being coated with a dielectric passivation layer. The application of MACE etching for more than 5 s significantly enhanced light trapping efficiency. Surface recombination in the roughening emitter layer was suppressed by the application of a TiO2 passivation film deposited by e-beam evaporation at a low deposition rate in conjunction with substrate rotation. A thin film silicon solar cell that underwent MACE for 10 s with a 15 nm TiO2 passivation layer produced an impressive 51% improvement in conversion efficiency (from 6.27% to 9.62%), compared to reference solar cells fabricated without MACE processing or dielectric passivation.