Influence of sulfurization temperature on grain growth in Cu₂ZnSnS₄ thin films synthesized for solar cell applications

Abstract Copper-zinc-tin-sulfur (CZTS) thin films, prepared through a dip-coating solution method, present a highly attractive option as absorber materials for thin-film solar cells. This is due to their affordability, environmentally friendly composition, and abundant availability of raw materials. Although films processed with hydrazine-based solutions have achieved the highest efficiency of approximately 12.6%, the toxic and carcinogenic nature of hydrazine negates these advantages. In the ongoing global research on solution-based processing methods, the size of the grains has emerged as a critical factor in the fabrication of efficient solar cells. In our study, we have successfully prepared CZTS thin films with a pure kesterite phase, characterized by large micro-sized grains, using a dip-coating process with an ethanol-based precursor solution, followed by sulfurization. We investigated how the grain size evolves with varying sulfurization temperatures. Notably, we observed that increasing the temperature led to larger and more uniform grain growth. These results underscore the potential of our approach for the straightforward production of high-quality films with sizable grains, ultimately enhancing their photosensitivity and making them a promising candidate for efficient solar cell applications.