Rapid Surface Reconstruction in Air‐Processed Perovskite Solar Cells by Blade Coating

Abstract Blade coating has been developed to be an essential technique for large‐area fabrication of perovskite solar cells (PSCs). However, effective surface treatment of the perovskite layer, which is a critical step for improving PSC performance, remains challenges during blade coating due to the short interaction time between the modification solution and the perovskite layer, as well as the limited selection of available organic solvents. In this study, a novel modifier N , N ‐diphenylguanidine monohydrobromide (DPGABr) dissolved in acetonitrile (ACN) is blade coated on the MA 0.7 FA 0.3 PbI 3 surface in air to reconstruct the perovskite surface in hundreds of milliseconds. This work finds that the solvent ACN rapidly dissolves organic iodide of the perovskite layer and leads to a PbI 2 ‐rich surface, providing reactive sites for DPGABr to form a thin DPGABr/PbI 2 complex layer. This surface reconstruction can effectively passivate defects and induce n‐type doping on the perovskite surface to facilitate electron transfer. The resultant devices show a 15% improvement in average power conversion efficiency. More importantly, the devices with the surface reconstruction show outstanding long‐term stability, with negligible performance degradation even after 1‐year storage in air. This study presents a convenient and effective approach for improving the performance of blade‐coated PSCs prepared in air.