Numerical optimization and comparative analysis of bandgap-engineered BaZrS3 chalcogenide perovskite solar cells with site-specific alloying

This study explores bandgap engineering in BaZrS₃-based photovoltaic devices to enhance their performance and optoelectronic properties. By systematically optimizing the electron transport material (WS₂) and hole transport layer (Cu₂O), as well as key absorber parameters and defect characteristics, we minimized recombination losses and improved charge carrier dynamics. Work function alignment of front and back metal contacts was achieved to optimize energy level matching, while temperature variation analysis validated device stability under operating conditions. The study also investigates site-specific alloying strategies, including Ca substitution at the Ba site, Sn substitution at the Zr site, and Se substitution at the S site, to tailor the bandgap and absorption properties. The resulting devices achieved extended cutoff wavelengths of 725 nm, 983 nm, 837 nm, and 918 nm for BaZrS₃, (Ba,Ca)ZrS₃, Ba(Zr,Sn)S₃, and BaZr(S,Se)₃, respectively. Corresponding efficiencies were 18.13 %, 22.23 %, 21.84 %, and 22.71 %, showcasing the benefits of bandgap engineering in improving both spectral response and power conversion efficiency. This work provides a comprehensive framework for optimizing chalcogenide perovskite devices, offering valuable insights for future research on tandem and multijunction solar cells, and highlights the potential of bandgap engineering in achieving high-efficiency, stable, and sustainable photovoltaic technologies.