Synthesis and Properties of New Dialkoxyphenylene Quinoxaline-Based Donor-Acceptor Conjugated Polymers and Their Applications on Thin Film Transistors and Solar Cells

Synthesis, properties, and optoelectronic device applications of four new bis-14-(2-ethyl-hexyloxy)-phenyllquinoxaline(Qx(EHP))-based donor-acceptor conjugated copolymers are reported, in which the donors are thiophene(T), ditbiophene(DT), dioetylfluorene(FO), and didecyloxyphenyleiie(OC10). The optical band gaps (E-g) of PThQx(EHP), PDTQ(EHP), POCIODTQ(EHP), and PFODTQ(EHP) estimated from the onset absorption are 1.57, 1.65, 1.77, and 1.92 eV, respectively. The smallest E-g of PThQx(EHP) among the four copolymers is attributed to the balanced donor/acceptor ratio and backbone coplanarity, leading to a strong intramolecular charge transfer. The hole mobilities obtained from the thin film transistor (TFT) devices of PThQx(EHP), PDTQ(EHP), POC10DTQ(EHP), and PFODTQ(EHP) are 2.52 x 10(4), 4.50 x 10(3), 4.72 x 10(5), and 9.31 x 10(4) cm(2) V-1 s(1), respectively, with the on-off ratios of 2.00 x 10(4), 1.89 x 10(3), 4.07 x 10(3), and 2.30 x 10(4). Polymer solar cell based on the polymer blends of PFODTQ(EHP), PThQx(EHP), POC10DTQ(EHP), and PDTQ(EHP) with [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) under illumination of AM1.5 (3.00 MW cm(-2)) solar simulator exhibit power conversion efficiencies of 1.75, 0.92, 0.79, and 0.43%, respectively. The donor/acceptor strength, molecular weight, miscibility, and energy level lead to the difference on the TFT or solar cell characteristics. The present study suggests that the prepared bisf4-(2-ethyl-hexyloxy)-phenyllquinoxaline donor-acceptor conjugated copolymers would have promising applications on electronic device applications. (C) 2008 Wiloy Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 973-985, 2009