Constructing of Cu2ZnSnS4 thin films with enhanced optical properties for solar cell application

Abstract

Thin films of Cu2ZnSnS4 (CZTS) were created utilizing the thermal evaporation method. For the (CZTS) nanoparticles, thermogravimetric analysis (TGA) was initially carried out. According to TGA analysis, different annealing temperatures (400, 450, 475, and 500 °C) were used to anneal the (CZTS) thin films. Investigations were done into how different annealing temperatures affected the structural, morphological, and optical characteristics of the CZTS films. The development of a thin CZTS crystal with a high-quality crystal structure has been demonstrated by XRD patterns and Raman spectra. Using Debye-Scherrer's equation, the crystallite size for CZTS thin films was determined to be between 8 and 69.9 nm. As the annealing temperature rises, crystallite size increases. Using a double-beam computer-controlled spectrophotometer with a 400–2500 nm wavelength range, the optical characteristics were examined. While the reflectance was discovered to increase with an increase in annealing temperature, the transmittance was found to decrease. Calculating the extinction coefficient and refractive index was done using Kramers-Kronig relations. Using Tauc's relation, the optical energy gap was estimated, and it was discovered that it shrank as annealing temperature was raised. The (CZTS) thin film that was annealed at 500 °C had the highest power conversion efficiency (PCE).