Band-Offset-Governed Design of Lead-Free SrTaO2N Wide-Bandgap Perovskite Solar Cells: A SCAPS-1D Study of Different ETL/HTL Configurations

This work establishes a SCAPS-1D design framework for SrTaO2N wide-bandgap solar cells by combining six ETL/HTL configurations with signed band-offset analysis. A controlled one-factor rear-ΔEV sensitivity study further isolates the voltage-loss mechanism, showing an almost linear reduction in VOC while JSC remains nearly unchanged. The results provide a bounded interface-design rule for improving voltage retention in STON-based devices and support its future assessment as a lead-free tandem-top absorber.