Fluorinated triphenylamine-based dopant-free hole-transporting material for high-performance inverted perovskite solar cells

A fluorinated methoxytriphenylamine-based small molecule H2 is demonstrated as an effective hole-transporting material (HTM) to simultaneously enhance the efficiency and stability of the dopant-free inverted perovskite solar cells (PSCs). The fluorine-methoxytriphenylamine hybrid strategy in H2 is found to improve energy level alignment, hole extraction, and most importantly, the film morphology, which enables the growth of high quality perovskite active layer and superior interfacial contact. Consequently, the dopant-free H2-based inverted PSCs achieve an excellent efficiency of 18.69% with negligible hysteresis and good ambient stability, representing one of the best dopant-free organic-small-molecule HTMs for conventional perovskite MAPbI3 PSCs reported thus far. These results demonstrate the promising applications of fluorine-methoxytriphenylamine hybrid strategy in designing efficient and stable HTMs for dopant-free PSCs.