A π-Conjugated Molecular Bridge Strategy for Constructing Efficient Hole Transport Pathways in Inverted Perovskite...

Metal halide perovskite solar cells (PSCs) hold promise for next-generation photovoltaics but are restricted by suboptimal efficiency and poor long-term stability. In inverted PSC architectures, self-assembled monolayers (SAMs) are widely employed as hole-selective layers (HSLs) due to their favorable energy-level alignment and negligible parasitic absorption. However, traditional SAMs often exhibit weak intermolecular interactions, leading to film aggregation, poor interfacial contact, and severe nonradiative recombination. To address these issues, we designed a multifunctional π-conjugated molecule, 2TPA-SP, featuring a spirofluorene-bridged backbone that promotes strong π-π stacking with carbazole-based SAMs. This molecular design enhances film compactness and interfacial coverage. Additionally, methoxy groups within the structure coordinate with undercoordinated Pb²⁺, effectively passivating interfacial defects. Triphenylamine moieties further enhance hole extraction and transport. Devices incorporating 2TPA-SP achieve a satisfactory PCE of 26.45% and retain 93.6% of the initial efficiency after 1000 h of continuous illumination under AM 1.5 G conditions. Moreover, a 10 cm × 10 cm mini-module also demonstrates a high efficiency of 22.26%, underscoring both the scalability and practical potential of this approach for future PSC applications.