Dimeric Carbazole Core Based Dopant‐Free Hole Transport Material for n‐i‐p Planar Perovskite Solar Cell.

A profitable approach for improving the stability of n‐i‐p planar perovskite solar cell (PSC) is developing dopant‐free hole transport materials (HTMs) with desirable intrinsic charge transport properties. In this work, by adopting a metal‐free catalytic intramolecular C─C coupling reaction, a carbazole dimer‐based fused‐ring is synthesized, and further developed a small molecular dopant‐free HTM abbreviated as NCz‐DM with appropriate energy level, excellent hole transport and film formation properties. Applied in n‐i‐p planar PSC, an impressive power conversion efficiency (PCE) of 24.0% is achieved, together with enhanced humidity, thermal and light stability, which is among the high level of ever‐reported results for PSCs utilizing small molecular dopant‐free HTM. [ABSTRACT FROM AUTHOR]