The influence of deposition temperature in the photovoltaic properties of spray deposited CZTS thin films

• Influence of temperature on the properties of CZTS thin films were investigated.
• The structure of CZTS was confirmed by XRD and Raman spectra.
• The average roughness and grain size increases at higher deposition temperature.
• The band gap lies between 1.45 and 1.55 eV and absorption coefficient ∼106 cm−1.
• It exhibits p-type conductivity and suitable for the fabrication of solar cells.

Thin films of Cu2ZnSnS4 (CZTS) is one of the most promising kesterite semiconductor materials for absorption layer in thin film solar cells because of its suitable optical band gap (1.5 eV), cost-effective and eco-friendly nature. CZTS thin films were successfully deposited on soda lime glass substrates using spray pyrolysis and the effect of variation of substrate temperature on the structural and optoelectronic properties was investigated. The powder X-Ray diffraction of the deposited thin films showed that the crystallinity was improved with increasing substrate temperature and it has a polycrystalline nature with (1 1 2), (2 2 0) and (1 1 6) phases. Surface morphology of the films was studied employing Atomic Force Microscopy which reveals that the average roughness and grain size increases when the substrate temperature increases. Optical band gap of the films had been studied using UV–Vis–NIR spectrometer and was found to be 1.40–1.60 eV which is close to the ideal band gap for highest theoretical conversion efficiency of solar cell. Hall measurements revealed that the films are p-type, with a carrier concentration between 1.524 × 1017 cm−3 and 4.218 × 1017 cm−3 and also the microstructure of these CZTS thin films were studied using Raman spectroscopic measurements.