Proton Transfer‐Hydrogen Bonds Network for Highly Efficient and Stable Inverted Perovskite Solar Cells

Abstract The development and application of self‐assembled monolayer (SAM) has revolutionized the advancement of inverted perovskite solar cells (PSCs). However, the performance of inverted PSCs remains limited by intrinsic defects in perovskite thin films, primarily due to inadequate control over crystallization on the poor‐quality SAM substrates. Here, we reported a proton transfer‐hydrogen bond network using a multifunctional additive phenylguanidine carbonate over a co‐adsorbed SAM (Co‐SAM) system. This strategy promoted the formation of guanidinium‐formamidinium hydrogen‐bonded complexes, which stabilize intermediate phases, suppress the generation of impurity phases during nucleation and accelerate the transition from δ‐phase to α‐phase. The significantly delayed crystallization process successfully induced large perovskite grains with suppressed intrinsic defects. Moreover, a high coverage, uniformity, and dense molecular packing was achieved for the Co‐SAM, ensuring an excellent growth substrate for subsequent perovskite deposition. PSCs ultimately achieved a power conversion efficiency (PCE) of 26.65%, with enhanced operational stability‐retaining 92.5% of initial PCE after >1200 h of maximum power point tracking.