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.