Phenothiazine‐Phenoxazine Hybrid Cross Hole‐Transporting Material for High Performance Perovskite Solar Cell

Abstract Hole transport materials (HTMs) critically influence perovskite solar cell (PSC) performance through three key mechanisms: facilitating hole transport, blocking electron recombination, and protecting the perovskite layer. Herein, we present novel HTMs featuring diphenothiazine (D‐PTZ) and diphenoxazine (D‐POZ) core architectures. Comprehensive characterization reveals that the hybrid cross phenothiazine‐phenoxazine (PTZ‐POZ) synergistically integrates the complementary advantages of D‐PTZ and D‐POZ demonstrating good solubility, improved film uniformity, and superior hole mobility. When implemented in small‐area PSC (0.0625 cm 2 ), PTZ‐POZ achieves record power conversion efficiency (PCE) of 25.85% with negligible hysteresis, outperforming D‐PTZ (23.09%) and D‐POZ (14.33%) based reference devices and representing the highest PCE reported to date for phenothiazine/phenoxazine‐based HTM devices. Additionally, the large‐area PSC (1.0 cm 2 ) based on PTZ‐POZ also achieved a high PCE of 23.23%. Moreover, the engineered HTM also exhibits exceptional stability, maintaining 90.4% of initial PCE after 1080 h at 40%s–50% humidity and ambient temperature. This study establishes a novel molecular design paradigm for developing low‐cost high‐efficiency PSCs.