Phosphotungstic Acid Regulated Chemical Bath Deposition of Sb2S3 for High-Efficiency Planar Heterojunction Solar Cell

Chemical bath deposition is a convenient method for preparing Sb2S3 film which is considered as a promising photovoltaic material. However, impurity phases such as Sb2O3, SbOCl, Sb-2(SO4)(3) and Sb(OH)(3) are inevitably generated in this solution process. Herein, we demonstrate that phosphotungstic acid in the precursor solution is able to suppress the formation of oxide and oxyhalide by-products, leading to considerably optimized composition and crystallinity for solar cell applications. With this method, a remarkable improvement of power conversion efficiency from 1.91 % to 4.61 % is obtained, which is also the highest efficiency in planar heterojunction solar cells by solution processed Sb2S3 absorber layer.