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

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 cm²), 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 cm²) 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.