Use of Etching to Improve Efficiency of the Multicrystalline Silicon Solar Cell by Using an Acidic Solution

Abstract

Surface texturing methods using an alkaline solution for monocrystalline Si (c-Si) solar cells have been widely accepted to improve cell performance. However, multicrystalline Si (mc-Si) cells are difficult to be texturized by alkaline etching, because the grains in the substrates are randomly oriented. In this study, we considered a HF/HNO 3/H 2O acid solution for texturing the mc-Si cells. The conversion efficiency of mc-Si solar cells textured with the solution (HF/HNO 3/H 2O = 30:1:2.5) has relatively high values. In our study, sufficient light confinement is achieved, which contributes to the improvement of both the short circuit current and the conversion efficiency of the acid textured cells. The optimal acid etching ratio HF:HNO 3:H 2O = 30:1:2.5 with etching time of 60 s and lowering 41.9 % of the R value can improve 111.8 % of the conversion efficiency (η) of the developed solar cell. More detailed information is used to measure the internal quantum efficiency (IQE) and the lifetime of minority carriers. Thus, the acid texturing approach is instrumental to achieve high efficiency in mass production using relatively low-cost mc-Si as the starting material with proper optimization of the fabrication steps.