Low-temperature synthesis and characterization of the single chalcopyrite phase CuInS2 compound by vacuum sintering method

We report herein low-temperature synthesis and characterization of the single chalcopyrite phase CuInS2 compound by vacuum sintering method. In this study, the ball-milled precursors including copper, indium, and sulfur powders were sintered under vacuum at various temperatures ranging from 423 K to 823 K. The product sintered at 523 K showed the phases of CuInS2, CuxS and CuIn11S17, and the products sintered above 623 K were identified as the single chalcopyrite phase and close to stoichiometry by X-ray diffraction, Raman scattering and energy dispersive X-ray spectroscopy. The band gap value of the CuInS2 compound was estimated as about 1.53 eV by optical transmittance and reflectance spectra, which is close to the ideal band gap for photovoltaic devices.