Buried Interface Chelating Molecular Bridge Strategy Enables Highly Efficient and Stable Inverted Perovskite Solar Cells

ABSTRACT [4‐(3,6‐dimethyl‐9H‐carbazol‐9yl)butyl]phosphonic acid (Me‐4PACz) self‐assembled monolayers (SAMs) as hole‐transport layers (HTLs) have enabled remarkable performance in inverted perovskite solar cells (PSCs). However, the uneven coverage and terminal carbazole groups of Me‐4PACz SAMs cannot effectively passivate defects, which constrains further improvements in device performance. Herein, we use post‐assembled chelating molecular bridge strategy to introduce 2,5‐thiophenedicarboxylic acid (TDCA) as interface layer between Me‐4PACz HTL and perovskite layer, which not only ensures the priority deposition of the primary Me‐4PACz SAM, but also fills voids within the Me‐4PACz HTL to form dense and uniform bilayer HTL. In addition, the C═O groups and S atom in TDCA can chelate with uncoordinated Pb 2+ in perovskite, effectively passivating buried interface defects. Consequently, the PSCs based on TDCA interface layer achieved a champion PCE of 26.15%. It is noteworthy that this strategy has excellent process compatibility. The PCE of narrow‐bandgap (1.55 eV) and wide‐bandgap (1.77 eV) PSCs are 26.20% and 21.65%, respectively. Furthermore, the corresponding PSCs maintain more than 94.2% and 90.7% of initial efficiency after 2500 h in a glove box and 1000 h under one‐sun illumination, respectively. This work provides a promising buried interface molecular bridge strategy for high‐performance PSCs.