Presentation Information
[9p-PB1-14]Analysis of structure-property relationships in crystals of BFD oligomers
〇Hayato Taguchi1, Seiya Yokokura1,2, Hiroki Waizumi1,2, Toshihiro Shimada1,2 (1.Grad. Sch. Chem. Sci. Eng., Hokkaido Univ., 2.Fac. Eng., Hokkaido Univ.)
Keywords:
organic semicomductors,Crystal structure
This study examines BFD-based oligomer crystals as model systems for n-PBDF, a conductive polymer with transparency, conductivity, and air stability. Although n-PBDF is promising for thermoelectric devices and electrochemical transistors, polymer disorder obscures its intrinsic structure–property relationship. Although CCD units generated by isomerization are believed to hinder charge transport, the underlying mechanism remains unclear. Here, BFD, BFD2, and CCD crystals were compared, and their electronic couplings and band structures were calculated. BFD and BFD2 formed brickwork packing with short-axis slipped stacks, close carbonyl-related contacts, transfer integrals of about 100 meV, and band widths of about 0.4 eV. In contrast, CCD showed long-axis slipped packing, smaller dispersed transfer integrals, and a narrower band width of about 0.25 eV. Thus, CCD suppresses charge transport not only through its shallower LUMO level, but also through unfavorable packing and weaker coupling.