Variation of back reflector morphology in n–i–p microcrystalline silicon thin film solar cells using texture-etched ZnO

Abstract

Surface morphology of ZnO layers was varied by changing etching time and statistically analyzed in terms of the root mean square roughness and the distribution of surface feature (crater) size. The texture-etched ZnO covered with Ag and ZnO layers was applied into n–i–p μc-Si:H solar cells as back reflectors. The effects of the back reflector morphologies on solar cell performances were investigated. The correlation between the back reflector morphology and the light trapping properties of solar cells was investigated, including the effect of crater size on the short circuit current density (JSC). We find that craters with the lateral size between 900nm and 2500nm are beneficial for light trapping and are suggested to be mainly responsible for the change in JSC in the solar cells. An improved light trapping results in an increase in JSC by 4.5mA/cm2 (25%) relative to a flat back reflector.