The Effect of Substrate Temperature on the Phase Formation of Spray-Pyrolysed Ternary Cu2SnS3 for Thin-Film Solar Cells

Abstract

The Cu2SnS3 thin films are deposited by spray pyrolysis at different substrate temperatures to ensure the phase purity of the photovoltaic absorber material. No pH controlling agent and complexing agent are used in the preparation. Here, Cu2SnS3 thin films have been deposited with the substrate temperature ranging from 200 to 280 °C for finding the optimum phase formation temperature. From the XRD study it is found that the films deposited at the substrate temperature of 280 °C are pure in phase with uniform deposition throughout the film active area. Subsequently, films are heat-treated in rapid thermal annealing furnace under sulphur atmosphere at 420 °C, which shows increased crystallinity of the tetragonal Cu2SnS3 phase with the preferred orientation along (112) crystal direction. Optical study reveals a bandgap (Eg) of 1.39 eV with the absorption coefficient more than 104 cm−1. The films are p-type semiconductor with the electrical conductivity of 2.5 × 102 S/cm. Our study establishes the potential of the Cu2SnS3 thin films developed using inexpensive spray deposition for photovoltaic applications.