Hydrothermal fabrication of chalcopyrite-type CuInS2 film and their optical properties

In this work, CuInS2 (CIS) particles were prepared by a simple hydrothermal method using the precursors of Cu(NO3)(2), In(NO3)(3) and CS(NH2)(2) in aqueous solution at 160 degrees C for 2 h, followed by a spin coating process on the quartz substrate, so a CIS thin film was obtained. The CIS film was analyzed by means of a transmission electron microscope, an atomic force microscope, x-ray diffraction, energy dispersive spectroscopy, x-ray photoelectron spectroscopy and UV-visible absorption spectroscopy. The results show that the even and compact CIS thin film is composed of particles with a regular morphology and a uniform size distribution, with chalcopyrite structure. The crystalline quality of CIS film is significantly improved, growing along the (112) orientation. Its composition is close to the stoichiometric ratio (1: 1: 2) of the single CIS phase. Besides, the CIS thin film has an obvious absorption in the visible light region, and the band gap energy of the CIS film is approximately 1.40 eV. The method provides a potential new approach to fabricating CIS thin film applied in the field of solar cells.