The effects of annealing process on the characteristics of β-In2S3 powder in pellet form

Due to its significant expansion as a sustainable energy source, the investigation of thin-film-based solar cells is a very important field of research among materials scientists. Nowadays, CdTe based photovoltaic devices are developed using indium sulfide (In2S3) as potential material. This study reports the effect of the annealing temperature, up to 450 °C, on In2S3 physical properties, and the consequences for the use of the In2S3 in photovoltaic devices. Structural analysis on indium sulfide pellets, made from commercial indium sulfide powder, reveals that all the samples are polycrystalline, crystallizing in the tetragonal structure (β phase). Above the annealing temperature of 400 °C, indium oxide (In2O3) is also detected. Optical absorption, in the visible and near-infrared region, is close to zero for all the samples (as-prepared and annealed). The measured band gap energy decreases with annealing temperature up to 350 °C, and increases above this temperature. The conductance of the samples increases with increasing measured temperature, confirming the semiconductor behavior. This work provides an example of the potential application of β-In2S3, in the powder form, for environmental rehabilitation.