Spray deposited Cu2CoSnS4 thin films for photovoltaic application: Effect of film thickness

Abstract The Cu2CoSnS4 (copper cobalt tin sulfide) thin films have been prepared onto glass substrate at optimized substrate temperature of 350 °C by chemical spray pyrolysis method. The effect of film thickness on the structural, morphological, optical, surface wettability and photovoltaic properties has been studied by varying the quantity of precursor solution from 40 mL to 100 mL with an interval of 20 mL. X-ray diffraction study revealed the formation of stannite crystal structure of the films. For 383 nm film thickness, Field emission scanning electron microscopy analysis showed the compact and homogeneous flake like morphology. Energy dispersive X-ray analysis confirmed the presence of Cu, Co, Sn, and S elements in the copper cobalt tin sulfide thin films. The energy band gap values are found to be in the range from 1.52 eV to 1.56 eV. The surface wettability study of copper cobalt tin sulfide films with Na2SO4 electrolyte revealed the hydrophilic nature of the films. The power conversion efficiency of 2.33 % is obtained for the photoelectrochemical cell fabricated with 383 nm film thickness as a working electrode.