Impact of heating on the properties of CZTS thin film solar cells produced through sol-gel spin-coated

This paper investigates the influence of annealing temperatures on the properties of copper-zinc-tin sulfide (CZTS) thin films synthesized using a low-cost sol-gel spin-coating technique. The thin films were annealed at different temperatures: 340°C, 360°C, 380°C, and 400°C. Analysis of the X-ray diffraction data revealed a consistent kesterite structure in all thin films, with a preferred orientation along the (112) plane. Raman’s spectra confirmed the purity of the phase and confirmed the presence of the CZTS kesterite structure. The morphological and elemental compositions of the thin films showed significant fluctuations in response to changes in annealing temperature. This effect is due to the influence of temperature on the reaction dynamics during the preparation of the deposition solution. The optical properties showed a robust absorption coefficient (>104 cm−1) with optical bandgaps ranging from 1.38 to 1.72 eV. In particular, the CZTS sample annealed at 340°C showed superior crystallinity and outperformed others in optical and electrical properties. To expand the practical implications, the parameters derived from this study were theoretically integrated into a solar cell model (CZTS/(CdS or ZnS)/ZnO:i). Using SCAPS-1D simulation, efficiencies of 11.40% and 10.55% were predicted for the CdS and ZnS buffer layers, respectively. These results provide valuable information for optimizing CZTS thin films to improve solar cell performance.