Ion–Dipole Interaction Enabling Highly Efficient CsPbI3 Perovskite Indoor Photovoltaics

Abstract Metal halide perovskites are ideal candidates for indoor photovoltaics (IPVs) because of their easy‐to‐adjust bandgaps, which can be designed to cover the spectrum of any artificial light source. However, the serious non‐radiative carrier recombination under low light illumination restrains the application of perovskite‐based IPVs (PIPVs). Herein, polar molecules of amino naphthalene sulfonates are employed to functionalize the TiO 2 substrate, anchoring the CsPbI 3 perovskite crystal grains with a strong ion–dipole interaction between the molecule‐level polar interlayer and the ionic perovskite film. The resulting high‐quality CsPbI 3 films with the merit of defect‐immunity and large shunt resistance under low light conditions enable the corresponding PIPVs with an indoor power conversion efficiency of up to 41.2% ( P in : 334.11 µW cm −2 , P out : 137.66 µW cm −2 ) under illumination from a commonly used indoor light‐emitting diode light source (2956 K, 1062 lux). Furthermore, the device also achieves efficiencies of 29.45% ( P out : 9.80 µW cm −2 ) and 32.54% ( P out : 54.34 µW cm −2 ) at 106 ( P in : 33.84 µW cm −2 ) and 522 lux ( P in : 168.21 µW cm −2 ), respectively.