Interfacial engineering via dipolar fullerene derivative for efficient tin halide perovskite indoor photovoltaics

Modulating hot carrier dynamics is crucial in tin halide perovskite photovoltaics, particularly under indoor illumination with limited photon flux. Herein, a fullerene derivative bearing four piperazine groups (denoted as TPPC) is synthesized to engineer the perovskite/C 60 interface. The TPPC molecule exhibits a dipole moment of 1.97 Debye, leading to enhanced adsorption energy on perovskite surface and robust interfacial interaction. The newly formed surface dipole optimizes the interfacial energy level alignment via a cascade gradient, enabling modulation of interfacial hot carrier dynamics. Consequently, TPPC-treated photovoltaic devices achieve a champion power conversion efficiency (PCE) of 22.49% and a maximum output power density ( P out ) of 64.1 μW cm -2 under white light-emitting diode illumination (3000 K, 1000 lux, 285 μW cm -2 ). Large-area (1.21 cm 2 ) devices attain a PCE of 17.94% (certified: 15.93%) and a maximum P out of 51.2 μW cm -2 under the same illumination conditions.