Enhanced Efficiency and Stability of Wide‐Bandgap Perovskites via Br‐Rich Bulk and Surface 2D Passivation for Indoor Photovoltaics

Indoor photovoltaics (IPV) is a promising technology to power the rapidly developing Internet of Things (IoT) devices, offering advantages of distributed power source and reduced maintenance cost. Wide‐bandgap perovskite solar cells (PSCs), with the features of easy bandgap tuning and low‐cost solution process, hold significant potential for powering indoor IoT devices. However, the efficiency and stability of wide‐bandgap PSCs suffers from severe phase segregation and surface defects. Herein, a novel bromide‐rich 2D passivation strategy targeting both bulk and surface passivation of wide‐bandgap PSCs for IPV application is introduced. Ammonium salts with optimized alkyl chain length is confirmed to suppress the phase segregation in the bulk. Bromide‐rich 2D perovskite exhibit superior performance compared to their iodide counterparts, effectively suppressing nonradiative recombination and forming favorable energy band alignment with the electron transport layer (ETL). The wide‐bandgap PSCs achieved an impressive power conversion efficiency (PCE) up to 41.58% under 1000 lux light emitting diode (LED) illumination. Furthermore, the wide‐bandgap perovskite module efficiently powers a Bluetooth IoT sensor at 400 lux indoor illumination, which can sense and broadcast the environmental information. This work highlights the remarkable potential of wide‐bandgap PSCs for indoor IoT devices and provides valuable insights into enhancing the efficiency and stability of PSCs for future IoT applications.