Molecular engineering of dibenzo-heterocyclic core based hole-transporting materials for perovskite solar cells

Heterocyclic compounds play an important role in organic hole transport materials (HTMs) for perovskite solar cells (PSCs). Herein, a series of linear D-π-D HTMs (OCBz, S-CBz, SO2-CBz) with different dibenzo-heterocycles core (dibenzofuran, dibenzothiophene, dibenzothiophene sulfone) were designed and synthesized, and their applications in PSCs were investigated. The intrinsic properties (CV, UV–vis, hole mobility and conductivity) were systematically investigated, demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs. Benefiting from the excellent hole mobility and conductivity, good film forming ability, and outstanding charge extraction and transport capability of S-CBz, FAPbI₃-based PSCs using S-CBz as HTM achieved a PCE of 25.0 %, which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions (23.9 %). Furthermore, due to the interaction between S and Pb²⁺, S-CBz-based PSC devices exhibited improved stability. This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.