Design of a Unique Hole‐Transporting Molecule via Introducing a Chloro‐Involved Chelating Moiety for High‐Performance Inverted Perovskite Solar Cells

Abstract Hole‐transporting materials (HTMs) play an important role in transporting photogenerated holes, tuning the perovskite crystallization process, and passivating uncoordinated Pb 2+ defects for high‐performance inverted perovskite solar cells (PSCs). Herein, a unique cost‐effective small molecule‐type HTM based on a triarylamine core bearing a chloro‐assisted chelating moiety (named TPA‐CAA) is synthesized, which has excellent affinity to the perovskite precursor solution leading to smooth and uniform perovskite films. In comparison with the structurally similar molecule TPA‐AA with the absence of the chloro‐substituent, TPA‐CAA can form a chelate structure with Pb 2+ via the carbonyl and the adjacent chloro‐atom, which efficiently tunes the perovskite crystallization, passivates the defects, and enhances the hole transporting at the perovskite/HTL interface. Eventually, the TPA‐CAA‐based inverted PSC achieves a champion power conversion efficiency (PCE) of 21.56% (19.64% and 18.84% for the poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA) and TPA‐AA ones, respectively) with a high open‐circuit voltage ( V OC ) of 1.113 V. Moreover, the stability of the TPA‐CAA‐based device is notably improved, and the PCE maintains over 80% of its initial value over 1000 h storage in ambient air (25 °C, relative humidity 30–40%) without encapsulation, in comparison to that of the PTAA device (only 50% of the initial value left over 1000 h).