Managing Secondary Phase Lead Iodide in Hybrid Perovskites via Surface Reconstruction for High‐Performance Perovskite Solar Cells with Robust Environmental Stability

Abstract

AbstractRationally managing the secondary‐phase excess lead iodide (PbI2) in hybrid perovskite is of significance for pursuing high performance perovskite solar cells (PSCs), while the challenge remains on its conversion to a homogeneous layer that is robust stable against environmental stimuli. We herein demonstrate an effective strategy of surface reconstruction that converts the excess PbI2 into a gradient lead sulfate‐silica bi‐layer, which substantially stabilizes the perovskite film and reduces interfacial charge transfer barrier in the PSCs device. The perovskite films with such bi‐layer could bear harsh conditions such as soaking in water, light illumination at 70 % relative humidity, and the damp‐thermal (85 °C and 30 % humidity) environment. The resulted PSCs deliver a champion efficiency up to 24.09 %, as well as remarkable environmental stability, e.g., retaining 78 % of their initial efficiency after 5500 h of shelf storage, and 82 % after 1000 h of operational stability testing.