Solvothermal synthesis of CuInS2 powders and CuInS2 thin films for solar cell application

Abstract

In this study, a facile solvothermal method was developed to prepare CuInS2 powders and CuInS2 thin films. The CuInS2 powders and CuInS2 thin films were prepared by solvothermal route using the precursor of Copper (II) chloride, indium (III) nitrate, thiourea, oxalic acid, hexadecyl trimethyl ammonium bromide and ethanol. The morphology, crystallographic structure, chemical composition and optical band gap of CuInS2 powders and CuInS2 thin films were investigated using scanning electronic microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and UV–vis spectroscopy. The results reveal that both CuInS2 powders and CuInS2 thin films are in chalcopyrite phase. The CuInS2 powders are mainly composed of flower-like microspheres. Both microstructure of the sphere surface and diameter of sphere are affected by indium nitrate concentration in precursors. The CuInS2 thin films are composed of a large number of uniform flower-like nanosheets, and the nanosheets become smaller in size and denser in distribution density with increasing concentration of thiourea. The optical band gap is found to be 1.44 and 1.52 eV for CuInS2 powders and CuInS2 thin films, respectively. The deposition mechanism of the CuInS2 is discussed.