Development of flexible silicon thin-film solar cells on nanotextured Ag/Al:Si bilayers

Highly textured Ag/Al:Si back reflectors were used to improve the short-circuit current density of flexible nanocrystalline silicon thin-film solar cells by means of enhanced light trapping. A nanotextured topography with a root-mean-square (σ_rms) surface roughness of 60.1 nm was induced at low substrate temperature of 100°C by abnormal grain growth of dc-sputtered Al:Si films. After depositing highly reflective Ag films on nanotextured Al:Si films, effective light scattering of the long wavelength over 500 nm was achieved, resulting in enhanced absorption of weakly absorbing, long-wavelength light in the solar cells. The effects of nanotextured surfaces of the bilayers on the light scattering properties and on the resultant cell performance were investigated.