Optimizing Sb2Se3 solar cells with CdIn2S4 buffer for high-efficiency and stability: a comprehensive analysis

The long-standing dependence of S b 2 S e 3 thin-film photovoltaics on CdS buffer layers continues to hinder device scalability due to parasitic UV absorption and unfavorable interface band energy. In this work, a simulation-guided interfacial engineering strategy is established by replacing CdS with C d I n 2 S 4 buffer layer. SCAPS-1D calculations demonstrate that C d I n 2 S 4 simultaneously increases the built-in electric field and suppresses defect-mediated interfacial recombination, leading to a significant enhancement in the open-circuit voltage (from 0.48 to 0.77 V), short-circuit current density (from 30.87 to 34.18 mA·cm −2 ), fill factor (from 67.8 to 72.16%), and overall efficiency (from 10.12% to 19.06%). Mott–Schottky analysis reveals a substantial improvement in the depletion region with an elevated built-in potential (from 0.78 to 1.05 V), whereas impedance spectroscopy indicates reduced recombination resistance and enhanced carrier extraction dynamics. These electronic improvements are coupled with the optical benefits of C d I n 2 S 4 , whose wide bandgap (2.6 eV) reduces parasitic absorption and increases UV photon utilization. Furthermore, the material’s thermochemical formation pathway in spray pyrolysis, governed by thiourea-derived sulfur release, ensures defect-tolerant growth and chemical compatibility with S b 2 S e 3 . This combined physicochemical–optoelectronic synergy positions C d I n 2 S 4 as a viable industrial alternative to CdS , offering a scalable pathway toward high-efficiency, environmentally friendly S b 2 S e 3 photovoltaics.