Cyclopentadithiophene-Based Hole-Transporting Material for Highly Stable Perovskite Solar Cells with Stabilized Efficiencies Approaching 21%

There is an urge to develop new hole-transporting materials (HTMs) for perovskite solar cells (PSCs), which can yield comparable power conversion efficiencies (PCEs) yet mitigate the issue of stability associated with the state-of-the-art HTM spiro-MeOTAD. Herein, we designed and prepared C2v-symmetric spiro-configured HTM-1 comprising a central acridine-cyclopentadithiophene core unit flanked with triarylamine moieties. PSCs containing a 40 nm thin HTM-1 layer for hole extraction yielded a stabilized PCE approaching 21% under standard illumination. Owing to its higher hole mobility (μh) at low electric field, an impressive short-circuit current density (JSC) of 24.7 mA cm-2 and a high fill factor (FF) of 0.77 have been achieved. More importantly, HTM-1-based PSCs presented an excellent long-term operational stability under continuous illumination for 400 h and thermal stability at 80 °C, which can be ascribed to its high glass transition temperature of 168 °C and superior moisture tolerance. Arguably, the confluence of high performance and remarkable stability will lead to the development of technologically interesting new, stable, and efficient PSCs.