Optimized surface passivation via para-carbonylated polymers for durable MAPbl3 perovskite solar cells

Abstract

Developing polymers with passivation functions has been demonstrated to be effective for fabricating efficient and durable perovskite solar cells (PSCs). In this work, para-carbonylated isophthalic acid (IPA) was introduced as the passivation group in polymeric hole-transport materials (HTMs) through density functional theory calculations and isomeric engineering, owing to its potential for lattice-matching coordination with Pb²⁺. By incorporating IPA into the molecular skeleton as a bridge linker, a flexible binaphthol-cored polymer, BN8, was successfully synthesized via mild esterification. Compared to the reference BN1 with the non-passivating ethyl linker, the synergistic steric-hindrance effect in BN8 consolidates the merits of its flexible backbone, further improving the solubility and film-forming ability. Moreover, the strong dipole–dipole interactions in BN8 facilitate efficient hole extraction/transport and effective surface passivation. Consequently, the inverted MAPbI₃-based PSCs with polymer BN8 exhibited a power conversion efficiency of 19.3% and good device stability, which is competitive with those using PTAA-based devices. This study introduces a versatile defect-passivation building block, paving new avenues for optimizing group passivation effects and surface regulation.