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

Abstract

Polycondensation via direct arylation of tetrafluorobenzene or octafluorobiphenyl was investigated for the synthesis of π-conjugated polymers consisting of fluorinated arylene units. The optimization of reaction conditions revealed that a combination of Pd(OAc)2 and P t Bu2Me-HBF4 is the most efficient catalytic system for the polycondensation reactions. The polycondensation reactions produced four types of π-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.

Pd- and Ni-catalyzed cross-coupling reactions in the synthesis of organic electronic materials

“…Copolymerization of 1,2,4,5-tetrafluorobenzene (TFB) with brominated dioctylfluorene (F8) or N -alkylcarbazoles has been achieved in the presence of Pd(OAc) 2 with P t Bu 2 Me and base (scheme 28) [98, 99]. The regioselectivity in C−H bond activation can be rather sensitive to the solvent system and reaction time, a significant limitation in direct arylation protocols [93].…”

Recent Advances in Polymer Organic Light-Emitting Diodes (PLED) Using Non-conjugated Polymers as the Emitting Layer and Contrasting Them with Conjugated Counterparts

“…Direct arylation polymerization (DAP) has recently attracted intense research attention, because it is more economical (fewer synthetic steps) and environmentally friendly (less organometallic by-products) than the traditional C-C bond formation chemistry. 130,131 PFO-TFP synthesized via DAP had a M n and PDI of 31.5 kDa and 3.5, respectively, in an 81% yield, 114 whereas the same polymer synthesized via Suzuki coupling showed a M n and PDI of 16.5 kDa and 2.2, respectively, in a 74% yield. 113 Both conjugated and non-conjugated polymers are economical because the majority of the two classes of polymers were obtained with >70% yields.…”

Development of Synthetic Method for ^|^pi;-Conjugated Polymers via Direct Arylation Polycondensation

“…The optimal conditions were also applicable to the reaction of octa uorobiphenyl instead of tetra uorobenzene (Scheme 3). 12 Several dibromoarylenes, such as dibromocarbazole analogs, are amenable to polycondensation under the optimized conditions. …”

“…The luminance of the device utilizing Polymer 1 in the hole blocking layer was higher than that of the device without the hole blocking layer over the entire current density region. 12 In addition, the dye containing polymers Polymer 4 and 5 served as active materials in bulk heterojunction solar cells with fullerene derivatives. 16 The polymers in Table 2 were assessed as OFET and OPV materials for evaluating the impact of the synthetic method on the characteristics of the optoelectronic materials (Table 3).…”