Synthesis and characterization of sprayed Zn-doped polycrystalline CuInS2 thin films

Copper indium disulphide (CuInS2) is an efficient absorber material for photovoltaic applications. In this work Zn (0.02 and 0.03 M) doped CuInS2 thin films are (Cu/In = 1.25) deposited onto glass substrates in the temperature range 300–400 °C. XRD patterns depict, Zn-doping facilitates the growth of CuInS2 thin films along (1 1 2) preferred plane and other characteristic planes. Optical studies show, 90% of light transmission occurs in the IR regions; hence Zn-doped CuInS2 can be used as an IR transmitter. The absorption coefficient in the UV–vis region is found to be in the order of 104–105 cm−1. Optical band gap energies increase with increase of temperatures (0.02 M – (1.93–2.05 eV) and 0.03 M – (1.94–2.04 eV)). Well defined, broad Blue and Green band emissions are exhibited. Resistivity study reveals the deposited films exhibit semiconducting nature. Zn species can be used as a donor and acceptor impurity in CuInS2 films to fabricate efficient solar cells and photovoltaic devices.