Comprehensive review of CZTS deposition techniques and experimental insights into low-temperature chemical synthesis of CZTS thin film solar cells

This review describes various deposition methods and subsequent processes for synthesizing Cu₂ZnSnS₄ thin films, a promising chalcogenide photovoltaic absorber material from an earth-abundant, non-toxic element inventory. CZTS promises a benign alternative route in contrast to conventional CIGS and CdTe photovoltaics based on rare and expensive elements. The review classifies CZTS fabrication as either a one-step or a two-step process and then elaborates on the different processes involved, such as PLD, electrodeposition, spray pyrolysis, spin coating, and sputtering. Investigation has been carried out in this work for each technique with respect to respective advantages and deficiencies regarding scalability, film quality, and any need for sulfurization to improve crystallinity and phase purity for efficient photovoltaic performance. This work also gives an insight into the experimental study through low-temperature chemical synthesis methodology for depositing CZTS films, while combining techniques such as spin coating and sulfurization in a controlled manner in order to achieve optimized material composition and electronic properties. Characterization through XRD and XPS revealed optimal stoichiometry with minor secondary phases. From this, one can consider that CZTS could be a very promising material candidate toward a scalable, efficient solar cell. The aim of this work is to underpin further advances in CZTS-based photovoltaics by optimization of deposition strategies and improvement in film quality for sustainable energy applications.