Synthesis of π-Conjugated Polymers Containing Fluorinated Arylene Units via Direct Arylation: Efficient Synthetic Method of Materials for OLEDs

Polycondensation via direct arylation of tetrafluorobenzene or octafluorobiphenyl was investigated for the synthesis of pi-conjugated polymers consisting of fluorinated arylene units. The optimization of reaction conditions revealed that a combination of Pd(OAc)(2) and (PBu2Me)-Bu-t-HBF4 is the most efficient catalytic system for the polycondensation reactions. The polycondensation reactions produced four types of pi-conjugated polymers having low highest occupied molecular orbital (HOMO) levels due to the strong electron-withdrawing nature of the fluorine substituents. Owing to the low HOMO levels, the synthesized polymers served as an efficient hole-blocking layer (HBL) in OLEDs.