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

Abstract

Abstract 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.