A Novel Self‐Assembled Hole‐Transporting Monolayer with Extending Conjugation for Inverted Perovskite Solar Cells

Abstract The application of self‐assembled monolayers (SAMs) as hole‐transporting materials has greatly improved the performance of inverted perovskite solar cells. Structure engineering of SAMs has proven to be an effective approach to enhance device performance. In this work, a novel SAM featuring extended conjugation is designed and synthesized, designated E‐CbzBT. Compared with CbzBT, E‐CbzBT exhibits enhanced asymmetric and noncoplanar screw‐shaped configuration, leading to uniform and tight packing on ITO. The uniform packing of E‐CbzBT increases the wettability of the perovskite precursor solution on the substrate, thereby facilitating perovskite crystallinity and suppressing interfacial trap density more effectively than CbzBT. Accordingly, inverted PSCs employing E‐CbzBT reach a champion power conversion efficiency of 25.15%, surpassing 24.06% for CbzBT‐based devices. Importantly, the E‐CbzBT‐based PSCs demonstrate superior ambient and thermal stability. The extending conjugation approach in SAMs represents a promising avenue for further advancements in perovskite solar cell technology.