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 Pb²⁺ 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.