Multifunctional Chemical Bridge and Defect Passivation for Highly Efficient Inverted Perovskite Solar Cells

The interfacial recombination at the perovskite/hole conductor interface generally results in significant energy losses in inverted perovskite solar cells (PSCs) with a p–i–n device architecture. Herein, a chemical bridge is built at the interface of poly(triarylamine) (PTAA)/perovskites by using 3-(1-pyridinio)-1-propanesulfonate (PPS) molecules to minimize interfacial recombination of charge carriers. Extensively theoretical calculations and experimental studies reveal that the pyridine of PPS molecule and the phenyl group of PTAA could be chemically coupled through π–π stacking, and the sulfonate at the other end of PPS molecule could anchor perovskites through a strong S═O···Pb coordination bond. The chemical bridge structure significantly suppresses charge carrier recombination at the interface of PTAA/perovskites. Meanwhile, after incorporation of PPS molecules as an additive in the perovskites to effectively passivate surface defects of perovskites, an efficiency of up to 21.7% with negligible hysteresis is achieved for inverted PSCs.