Minimizing Voltage Deficit in Perovskite Indoor Photovoltaics by Interfacial Engineering

Abstract Metal halide perovskites with bandgap of ≈1.8 eV are competitive candidates for indoor photovoltaic (IPV) devices, owing to their superior photovoltaic properties and ideal absorption spectra matched to most indoor light sources. However, these perovskite IPVs suffer from severe trap induced non‐radiative recombination, resulting in large open‐circuit voltage ( V _OC ) losses, particularly under low light intensity. Herein, an effective approach is developed to minimizing trap density by modifying the buried interface of perovskite layer with bifunctional molecular 2‐(4‐Fluorophenyl)ethylamine Hydrobromide (F‐PEABr). The benzene ring of F‐PEABr molecules can firmly anchor at the hole transporting layer by π–π stacking interaction, and the other ends can passivate the defects on the buried interface of perovskite layer. Based on that, the F‐PEABr modified perovskite IPVs achieved power conversion efficiency (PCE) of 42.3% with a remarkable V _OC of 1.13 V under 1000 lux illumination from a 4000 K LED lamp. Finally, perovskite IPV mini‐modules with area of 10.40 cm ² are demonstrated with a PCE of 35.2%. This interface modification strategy paves the way for crafting high‐performance perovskite IPVs, holding great potential for self‐powered internet of things applications.