Steric-hindrance-driven molecular wedges suppress SAM aggregation for 30.5 %-efficient perovskite/silicon tandem solar cells

Despite the exceptional efficiency of hole-selective self-assembled molecular layer (SAML), challenges persist due to SAML agglomeration and the incomplete passivation of buried perovskite defects, which hinder efficient hole transfer and compromise device stability. In this study, we introduce a novel V-shaped molecule, 4,4′-(perfluorocyclopent-1-ene-1,2-diyl)bis( N , N -bis(4-methoxyphenyl)aniline) (DPTAE), comprising a perfluorocyclopentene core flanked by two triphenylamine units, designed for incorporation at the perovskite buried interface. Owing to its sterically hindered, nonplanar structure, DPTAE functions as a “wedge” within the SAML, disrupting molecular aggregation and yielding an amorphous hole-selective layer. This redefined interfacial architecture facilitates enhanced charge extraction and minimizes interfacial defect states. As a result, the optimized wide-bandgap perovskite solar cells (PSCs) with a bandgap of 1.68 eV achieved an impressive power conversion efficiency (PCE) of 22.33 % and a fill factor ( FF ) of 86.24 %. Notably, the encapsulated devices exhibited superior stability under damp-heat conditions (ISOS-D-3, 85 % RH, 85 °C) with a T 88 of 1000 h, and maintained stable maximum power point tracking (ISOS-L-2, 40 % RH) with a T 92 of 500 h. Furthermore, DPTAE-based monolithic perovskite/silicon tandem solar cells attained a remarkable efficiency of 30.50 %. This innovative approach not only deepens our understanding of interfacial dynamics but also opens new avenues for engineering advanced solar cell architectures, thereby advancing perovskite-based photovoltaic technologies.