Simulation of narrow-bandgap mixed Pb–Sn perovskite solar cells with inverted p-i-n structure

Abstract

Mixed Pb–Sn perovskite solar cells are gaining growing research interest, due to the promise of narrow bandgaps and low toxicity. However, theoretical understanding of the device performance and the effect of band alignment in mixed Pb–Sn perovskite solar cells are still in lack. In this contribution, the effect of band offsets of FA0.5MA0.5Pb0.5Sn0.5I3 based perovskite solar cells with inverted p-i-n planar structure was analyzed using SCAPS-1D. The variations of conduction band offset (CBO) and valence band offset (VBO) at the absorber/interface defect layer (IDL)/charge transfer layer were simulated through altering the electron affinity (χ) of IDL. It was disclosed that built-in potential across the perovskite absorber and interface recombination were affected by the band offsets. Consequently, the optimum ranges of CBOs at the FA0.5MA0.5Pb0.5Sn0.5I3/IDL interface and the IDL/PCBM interface were set to be 0–0.3 eV and 0.15 ~ −0.15 eV, respectively. Meanwhile, the optimum ranges for VBOs at the FA0.5MA0.5Pb0.5Sn0.5I3/IDL interface and the IDL/PEDOT: PSS interface were set to be −0.3 ~ −0.1 eV and 0.1 ~ −0.1 eV, respectively. This study can provide theoretical guidance for the design of mixed Pb–Sn perovskite solar cells.