Improved Hole‐Selective Contact Enables Highly Efficient and Stable FAPbBr₃ Perovskite Solar Cells and Semitransparent Modules

Abstract Self‐assembled monolayers (SAMs) as the hole‐selective contact have achieved remarkable success in iodine‐based perovskite solar cells (PSCs), while their impact on bromine‐based PSCs is limited due to the poor perovskite crystallization behavior and mismatched energy level alignment. Here, a highly efficient SAM of (2‐(3,6‐diiodo‐9H‐carbazol‐9‐yl)ethyl)phosphonic acid (I‐2PACz) is employed to address these challenges in FAPbBr₃‐based PSCs. The incorporation of I atoms into I‐2PACz not only releases tensile stress within FAPbBr₃ perovskite, promoting oriented crystallization and minimizing defects through halogen‐halogen bond, but also optimizes the energy levels alignment at hole‐selective interface for enhanced hole extraction. Ultimately, a power conversion efficiency (PCE) of 11.14% is achieved, which stands among the highest reported value for FAPbBr₃ PSCs. Furthermore, the semitransparent devices/modules exhibit impressive PCEs of 8.19% and 6.23% with average visible transmittance of 41.98% and 38.99%. Remarkably, after operating at maximum power point for 1000 h, the encapsulated device maintains 93% of its initial PCE. These results demonstrate an effective strategy for achieving high‐performance bromine‐based PSCs toward further applications.