Minimizing Buried Interface Energy Losses with Post-Assembled Chelating Molecular Bridges for High-Performance and Stable Inverted Perovskite Solar Cells.

Self-assembled monolayers (SAMs) as hole-collecting materials have made remarkable progress in inverted perovskite solar cells (PSCs). However, the incomplete coverage of SAMs and the non-intimate interface contact between perovskite/SAMs usually cause inferior interface characteristics and significant energy losses at the heterojunction interface. Herein, a post-assembled chelating molecular bridge strategy using 5-(9H-carbazol-9-yl)isophthalicacid (CB-PA) is developed to modify the perovskite/SAMs buried interface. It is found that CB-PA can be chemically coupled with MeO-2PACz through π-π stacking between carbazole groups, and chelate with perovskite by forming double C═O···Pb bonds, thus constructing a bridge-connected interface to promote carrier extraction. Simultaneously, the post-assembled CB-PA can fill the voids of MeO-2PACz to form dense hybrid SAMs, resulting in uniform surface potential and improved interface contact. Moreover, CB-PA treatment also tends to induce the oriented crystallization of perovskite films, passivate interface defects, and release lattice stress at the buried interface. Consequently, the CB-PA-based inverted PSCs achieve a champion efficiency of 25.27% with superior operational stability, retaining ≈94% of their initial efficiency after maximum power point (MPP) tracking (65 °C) for 1000 h with ISOS-L-2I protocol. This work provides an innovative strategy to address the buried interface challenges for high-performance inverted PSCs.