Furan-Bridged SAMs: Anchoring Position Regulation for High-Performance Inverted Perovskite Solar Cells

Self-assembled monolayers (SAMs) play an important role in high-efficiency inverted perovskite solar cells (PSCs), which optimize interfacial contact and facilitate efficient hole extraction. Conventional SAMs adopt flexible alkyl chains as linkers, which may suffer from loose molecular arrangement, unfavorable surface coverage, and poor interfacial stability, limiting the overall device performance. Although SAMs incorporating rigid linkers have recently been reported, their molecular structures are mostly confined to phenyl-based linkers. In this work, a rigid furan linker was introduced for the first time to construct new SAMs, and we investigated how anchoring-group substitution positions affect device performance. Results showed that the rigid furan linker effectively enabled a uniform and dense coverage on the substrate. Moreover, TA2 with a carboxylic acid at C5 position possesses a larger dipole moment than TA1, which could more effectively modulate the substrate work function, facilitate interfacial charge transport, and suppress nonradiative recombination. Inverted PSCs based on TA2 achieved an optimized efficiency of 25.34%. Additionally, large-area devices (1 cm²) and modules (15.136 cm²) delivered efficiencies of 23.3% and 22.99%, respectively. This work suggests that furan could work well as the linker to connect the terminal group and the anchoring unit, establishing an effective molecular design guideline for high-performance SAMs.