<p>The increasing worldwide demand for energy-efficient and sustainable energy solutions has increased efforts towards the creation of low-cost, high-performance solar cell devices. In the range of thin-film photovoltaic compounds, copper zinc tin sulfide (CZTS) is singled out because of its toxicity-free nature, low production cost, and richness of constituent elements. With a direct band gap of ~ 1.5&#xa0;eV and a high absorption coefficient, CZTS is a promising absorber material. However, its overall device efficiency remains behind that of other thin-film technologies, which is attributed mainly to problems such as interface mismatches, high densities of defects, and secondary phase formation, which together account for large charge carrier recombination losses. In response to these shortcomings, this research investigates the fabrication of an improved buffer layer by using nontoxic zinc oxide and examines the possibility of using Al-doped zinc oxide (AZO) as an improved window layer. Both layers were deposited via the chemical spray pyrolysis (CSP) technique, which provides accurate control of the film composition, uniformity, and scalability. The suggested architecture is expected to reduce interface recombination, increase junction quality, enhance charge carrier mobility, and ultimately improve the efficiency of solar cells. The addition of Mn to ZnO facilitates bandgap modulation, enhances optical transparency, and enhances electrical conductivity; thus, it is an ideal substitute for traditional materials such as CdS. The integration of AZO and Mn:ZnO not only enhances device performance but also solves environmental issues related to cadmium-based layers. This research offers a promising and scalable pathway toward realizing high-efficiency, environmentally friendly CZTS solar cells, which will advance next-generation photovoltaic technologies and assist in meeting global clean energy targets.</p>