A facile Ion-Exchange assisted chemical bath deposition of CuSbS2 for thin film solar cells

Abstract

Copper antimony sulfur (CuSbS2) possesses a band gap of about 1.5 eV, high absorption coefficient of > 104 cm−1 and abundant compositions, which is considered as one of the potential photovoltaic absorbers. In this work, we propose a facile ion-exchange assisted chemical bath deposition (IEACBD) method, which uses Cu+ to replace Sb3+ from the matrix of Sb2S3 and then combine into CuSbS2 alloy. Through systematic study, we found that this ion-exchange is a simultaneous interdiffusion process of Cu+ and Sb3+ ions, which enables a uniform mixture of those two elements. But it also inevitably produces a Sb2O3 by-product on the surface of the film because of the alkaline environment of this chemical bath. To further remove it, we introduce a mild etching process with BDCA solution for Sb2O3 and then obtain a high-quality CuSbS2. Finally, we assemble an inorganic CuSbS2 solar cell with the architecture of FTO/TiO2/CdS/CuSbS2/Carbon/Ag, and delivering a photoelectric conversion efficiency of 0.75 %. This enriches the preparation method of CuSbS2 thin film and also provides guidance for the synthesis of the similar multiple chalcogen compounds.