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.