Light modulation strategy for highest-efficiency water-processed perovskite solar cells

Summary

Even though the power conversion efficiency (PCE) of the perovskite solar cell has been increased to 25.7%, essentially all solvent systems implemented for the deposition of perovskites are toxic to the environment. In this study, a light modulation strategy is used to prepare perovskite from an absolutely green water-solvent-based precursor (Pb(NO₃)₂/H₂O) system. The "light" effect significantly promotes the conversion kinetics and tailors the microstructure of lead halide, which will template the growth of perovskite. It is found that, when the light intensity reaches 1 Sun illumination, α-to-δ FAPbI₃ phase transition occurs. In the absence of light, metallic lead will be formed in perovskite. A unique iodide self-compensation effect is observed when the light intensity is optimized under 0.01 Sun illumination. The water-processed perovskite renders a record-high PCE of 23.74% and exhibits outstanding environmental stability. The feasibility of using water as the solvent paves an avenue for authentic green synthesis of perovskite materials.