Pyramid size control and its effects on the performance of silicon heterojunction solar cells

Abstract

This paper explores the formation process of surface pyramid morphologies and etching characteristics during the texturing process of silicon heterojunction (SHJ) solar cells. Our research discovered that pyramid size followed a linear correlation with etch amount at the transition point of planes {100} to {111} as the etch rate reached the transition point. Several techniques were developed to control pyramid size by monitoring and adjusting the etching amount at the transition point. Using this approach, the average pyramid size was successfully controlled from 0.5 µm to 12 µm. We concluded that for pyramids smaller than 1 µm or greater than 12 µm, the light reflectance, minority carrier lifetime (MCLT), and performance of SHJ solar cells were adversely affected. In conclusion, a desirable range of pyramid sizes was empirically determined by our investigation.