Tuning FAPbI3 for scalable perovskite indoor photovoltaics

Abstract

We report cesium lead bromide (CsPbBr₃)-alloyed formamidinium lead iodide (FAPbI₃) perovskites for scalable fabrication of indoor photovoltaics. We find that simultaneous alloying of FAPbI₃ with Cs and Br via CsPbBr₃ single crystals prolongs charge carrier lifetimes beyond 1 μs, and improves the morphology of perovskite films fabricated by blade coating in ambient air. The resulting alloy exhibits an improved bandgap alignment with the IEC TS 62607 B4 standard light spectrum, corresponding to white LED illumination, which leads to improved photovoltage. As a result, we report indoor solar cells with a power conversion efficiency of 32.6% for 0.049 cm² active-area devices; and 28.1% for 10.23 cm² modules under white LED illumination. Halide segregation, surprisingly, shows limited impact on the stability of these solar cells, which maintain 80% of their initial performance following 500 hours of operation under continuous high-irradiance indoor light.