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

A facile solution-based non-vacuum process for deposition of CuIn(Se,S) sub(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 C sub(4)H sub(11)N 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 [alpha]-phase possess a double-layer structure, and also incorporate with a little ordered vacancy compounds (OVCs) and Cu sub(2-x)Se impurities. The typical near stoichiometric CISeS films without Carbon residuals have superior photoelectric properties with carrier concentration of 3.46 x 10 super(16) N cm super(-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.