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The precisely customizable attributes of self-assembled monolayers (SAMs) molecules at the atomic level hold the potential to facilitate efficient hole selection and interface passivation simultaneously. However, the correlation between the exposure of passivating groups on the surface and device performance remains unexplored. Herein, we introduce two newly designed SAM molecules, Cbz2S and Cbz2SMe, incorporating cyclic disulfide or two flanking thiomethyls by modifying the 4,5-position of carbazole to adjust the Lewis basicity of the SAM-modified surface. Despite possessing suitable energetic alignment, Cbz2S with more-exposed sulfur atoms exhibited inferior device performance due to excessive reactivity, leading to an overpopulation of PbI2 crystallites at the buried perovskite interface. In contrast, the screening effect from the methyl groups of Cbz2SMe optimized SAM reactivity, exquisitely integrating buried interface passivation and hole selection together. Consequently, the champion inverted perovskite solar cell (PSC) employing Cbz2SMe achieved an impressive power conversion efficiency of 24.42%, accompanied by prolonged stability. This work demonstrates the feasibility of incorporating Lewis-basic passivation groups into SAM molecules and elucidates the relationship between the reactivity of SAM passivation groups and device performance. These findings provide valuable insights for the design of novel multifunctional SAM molecules, further advancing the performance of PSCs.
Jiang et al. (Tue,) studied this question.