Kinetic Enhancement of Self-Assembled Molecular Deposition via Catalytic Additive for Inverted Perovskite Solar Cells

Perovskite solar cells (pero-SCs) with inverted architectures have gained significant attention due to their operational stability and compatibility with tandem structures. The hole transport layer, particularly self-assembled molecules (SAMs), plays a crucial role in efficient charge extraction. However, optimizing the binding kinetics of SAMs to metal oxide substrates remains unexplored. Here, we introduce a catalytic additive 4-dimethylaminopyridine (DMAP) to enhance the adsorption of phosphonic acid-based SAM on indium tin oxide. DMAP facilitates the formation of a phosphorylpyridinium intermediate, which accelerates the binding reaction and improves SAM film density and uniformity. Spectroscopic and microscopic analyses confirm the intermediate formation and enhanced surface coverage. The optimized SAM layer promotes better perovskite film quality, reduces interfacial defects, and suppresses non-radiative recombination. Consequently, the optimized pero-SCs achieve a power conversion efficiency of 26.93% (certified as 26.44%). Furthermore, the improved molecular packing enhances device stability, retaining 95% of initial PCE after 700 h of operation.