Dipole-engineered self-assembled monolayer for buried interface in fully textured perovskite-silicon tandem solar cells

Monolithic perovskite-silicon tandem solar cells (PSTs) represent a promising avenue for surpassing the efficiency limits of single-junction photovoltaics, but their performance is still hampered by significant open-circuit voltage (VOC) losses arising from interfacial inefficient charge extraction and non-radiative recombination. To mitigate these losses, we introduce a push–pull bridging molecule, 4′-amino-[1,1′-biphenyl]-4-carboxylic acid (ABBA), which forms a 2PACz/ABBA assembly through phosphor-amidate. The 2PACz/ABBA assembly suppresses 2PACz aggregation caused by π-π stacking while simultaneously enhancing the interfacial dipole moment, thereby facilitating the built-in electric field to promote more efficient hole extraction. Meanwhile, –COOH groups within ABBA passivate deep-level defects (e.g., uncoordinated Pb2+) at buried perovskite interface and contribute to the growth of perovskite films with large grains, reduced residual stress, and optimized energy level alignment. Consequently, the champion tandem device fabricated via the two-step sequential vapor-solution process achieves a PCE of 30.37 % and an open-circuit voltage (VOC) of 1.891 V. Furthermore, unencapsulated devices maintain 88 % of their initial performance after 1000 h under maximum power point tracking (MPPT), highlighting its superior stability.