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 (O-CBz, 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.