A novel non-vacuum process for the preparation of CuIn(Se,S)2 thin-film solar cells from air-stable, eco-friendly, metal salts based solution ink

Abstract

A facile solution-based non-vacuum process for deposition of CuIn(Se,S)2 (CISeS) absorber layers is presented in this work, which indicates a promising way for the low-cost applications in thin-film solar cells. Firstly, low-boiling-point solvents Monobutylamine C4H11N and Carbon disulfide CS2 are selected as the complexing and thickening agents and added into the Cu/In metal salts based solution. Thus the air-stable, eco-friendly solution ink is successfully synthesized through a simple solution synthesis route. The detailed chemical reaction mechanism and the influence of the composition of precursor solution have been discussed intensively as well. After sequential spin-coating, hot-treatment and selenization process, the high-quality CISeS films are obtained and then characterized by XRD, Raman, SEM, EDS, Metallographic microscope, Hall Effect measurement and UV–vis–NIR spectroscopy, respectively. It is found that the compact CISeS films with chalcopyrite α-phase possess a double-layer structure, and also incorporate with a little ordered vacancy compounds (OVCs) and Cu2−xSe impurities. The typical near stoichiometric CISeS films without Carbon residuals have superior photoelectric properties with carrier concentration of 3.46 × 1016 N cm−3 and band gap of 1.15 eV. Finally, the original first-made PV devices provide a power conversion efficiency (PCE) of 4.25%, which can be further improved by increasing the thickness of CISeS films and/or optimizing the selenization and sulfuration technologies.