Low-Trap-Density CsPbX₃ Film for High-Efficiency Indoor Photovoltaics

The continuous advancement of the Internet of Things (IoT) and photovoltaic technology has promoted the development of indoor photovoltaics (IPVs) that powers wireless devices. Nowadays, the CsPbX₃ perovskite has received widespread attention because of its high power conversion efficiency (PCE) in an indoor environment and suitable band gap for IPVs. In this work, we regulated the thickness of the photoactive layer (to optimize the carrier transport process without affecting indoor absorption) and bromine substitution (to adjust the band gap and improve the quality of the film) to reduce trap-assisted carrier recombination. A CsPbI_2.7Br_0.3 perovskite cell with excellent performance was obtained, which is superior to c-Si cells in a low-light environment. The optimized device achieved PCE values of 32.69 and 33.11% under a 1000 lux fluorescent lamp and white light-emitting diode (WLED) illumination. The J-V hysteresis of the device is also effectively suppressed. Moreover, it has a steady-state output power of 7.76 μW (0.09 cm², and can be enhanced by enlarging the areas), which can meet the consumption of many small wireless devices. It is worth noting that the optimized device has excellent applicability to be used in a complex indoor environment.