Novel technique for large area n-type black silicon solar cell by formation of silicon nanograss after diffusion process

Abstract

Metal-assisted chemical etching (MACE) method is the most convenient and cost-effective nanowire fabrication method compared to other nanowire fabrication processes although a major problem arises in silicon nanowire, formed by MACE solution during n-type c-Si solar cell fabrication steps. High-temperature boron diffusion in conventional open tube furnace breaks down the nanowire resulting in a non-uniform surface pattern which is responsible to decrease overall conversion efficiency of the finished cell. In this work, this drawback is resolved by considering silicon nanowire formation after diffusion step. A slow etchant is considered for nanostructure on diffused silicon wafer to protect the diffused junction. The generated nanowire size is very less and has forage-like structure, and so termed as nanograss. Surface morphology and the characterization of the silicon nanograss structure after diffusion process on large area (156 mm × 156 mm) c-Si solar cells using MACE method have been investigated elaborately. Further, the complete solar cell has been fabricated with an efficiency of 17.20%.