Impact on Structural, Morphological, and compositional properties of CZTS thin films annealed in different environments

The present study focuses on the impacts of annealing temperature in different ambiances on the morphological behavior and thin-film quality of CZTS nanoparticles. CZTS nanoparticles have been synthesized via the hot-injection colloidal route method. CZTS nanoparticles have been annealed in air, vacuum atmosphere, and sulphur environment (N₂ + H₂S(5%), respectively at 450 °C for 30 min. The structural, morphological, compositional, and optical properties of all CZTS thin films were analyzed. The volume fraction is increased in the vacuum annealed thin film keeping crystallite size as same as in the as-deposited film. This results in a reduction of cracks and voids and thus the surface defects of the vacuum annealed thin film as confirmed by scanning electron microscope (SEM). AFM also confirms the improved quality of CZTS thin film annealed in a vacuum. PL curves also confirm the minimum defects in the case of vacuum-annealed thin films. Thus, the study reveals that the best quality CZTS thin films i.e. films with the least pinholes, cracks, and voids without any significant change from the initial conditions can be obtained after annealing in the vacuum environment.