Effect of grain size and dislocation density on the performance of thin film polycrystalline silicon solar cells

Abstract

Three kinds of important properties of the solar cell were calculated: short-circuit current density, open-circuit voltage, and conversion efficiency. Two equations which show the relationship between the minority-carrier diffusion length and the grain size or the etch pit density were used for the calculation. The dependence of the properties on the cell thickness were estimated as a function of grain size and etch-pit density. The effect of the internal reflectance with varying minority-carrier diffusion length was also examined. The results show that thin film polycrystalline silicon solar cells have the potential to attain an efficiency of 17% even at a film thickness of 2 μm if the grain size is bigger than 10 μm and the etch-pit density of less than 1×106 cm−2. The principal requirement is to achieve efficient light trapping.