Optoelectronical properties of indium sulfide thin films prepared by spray pyrolysis for photovoltaic applications

Indium sulfide (In2S3) thin films have been prepared by the spray pyrolysis (SP) technique using indium acetate and N-N dimethyl thiourea as precursor compounds. Samples prepared at different temperatures and atomic ratio of In to S in the starting solution, (In/S)sol, have been characterized using several techniques. X-ray diffraction studies have shown that the preparation temperature (Tp) affects the crystallinity of the deposited materials as well as the optoelectronic properties. For (In/S)sol=1/8, the optical band gap (Eg) increases from 2.2 up to 2.67 eV when Tp increases from 250 up to 450 °C. For (In/S)sol=1 and Tp=450 °C, the deposited material shows n-type electrical conductivity with a dark value of 1 (Ωcm)−1, and Eg=2.04 eV. The In2S3 thin films prepared under these conditions have a big potential use as a window material for photovoltaic heterojunction devices.