Nanocrystalline thin films of CuInS2 grown by spray pyrolysis

Nanocrystalline thin films of CuInS2 were grown on glass substrates using the spray pyrolysis technique. An aqueous mixture of solutions of CuCl2, InCl3 and CS(NH2)2 was converted into a fine colloidal solution by adding acetonitrile, and was then sprayed on to heated glass substrates, to produce the nanocrystalline films of CuInS2. The films were characterized using XRD, TEM, electron diffraction, SEM, EDAX, AFM and optical transmission spectra. AFM and TEM micrographs together with electron diffraction and XRD show that the films grown in the temperature range 275–325 °C are made up of single phase nano-sized (10–25 nm) particles of CuInS2. XRD calculations show that the crystallite size of the films ranges from 8 nm to about 15 nm. Optical absorption studies show that the band gap of the sprayed CuInS2 films is in the range 1.48–1.54 eV.