Synergistic dual-interface modification for high-performance CsPbBr₃ perovskite solar cells: a combined experimental...

All-inorganic CsPbBr₃ perovskite solar cells (PSCs) suffer from efficiency losses due to their interfacial energy level mismatch. Herein, we propose a synergistic dual-interface modification strategy to improve the photoelectrical performance of C/CsPbBr₃/SnO₂-structure PSCs. At the CsPbBr₃/carbon interface, N,N'-dicyclohexylcarbodiimide (DCC) could elevate the CsPbBr₃ Fermi level to suppress the interfacial non-radiative recombination to increase the open-circuit voltage (V _OC). At the SnO₂/CsPbBr₃ interface, NH₄F could upshift the SnO₂ Fermi level to enhance the crystallinity of CsPbBr₃ to markedly improve the fill factor (FF). The optimized device could achieve a power conversion efficiency of 9.59% with a V _OC of 1.53 V and an FF of 82.4%. To elucidate the underlying mechanism, we established a dual-diode series model (DDSM), which revealed that the V _OC was governed by the CsPbBr₃/carbon barrier and the FF was controlled by the SnO₂/CsPbBr₃ barrier. The theoretical predictions were consistent with the experimental results, providing a robust framework for designing high-performance all-inorganic PSCs.