Low band gap materials have always been a focus of attention due to their potential applications in various fields. In this work, a series of asymmetric bistricyclic aromatic ene (BAE) compounds with fluorenylidene-cyclopentadithiophene (FYT) skeleton were facially synthesized, which were modified with different substituents (-OMe, -SMe). The FYT core exhibit twisted C=C bond with dihedral angles around 30°, and the introduction of -SMe group can provide additional S⋅⋅⋅S interaction between molecules, which is conducive to the charge transporting. The UV-Vis spectra, electrochemistry and photoelectron spectroscopy revealed that these compounds have relatively narrow band gaps, particularly, the -SMe modified compounds have slightly lower HOMO and Fermi energy levels than that of the -OMe modified compounds. Furthermore, PSCs devices were fabricated with the three compounds as HTMs, and FYT-DSDPA exhibit the best performance among them, revealing the fine-tuning band structure could influence properties of HTMs.
Keywords: asymmetric structure; bistricyclic aromatic ene; hole-transporting material; low bandgap material; redox reversibility.
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