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ABSTRACT The synthesis of donor-acceptor type semiconducting copolymers is described. Quinoxaline (QX) or difluorinated quinoxaline (DFQX) derivatives serve as electron acceptors, while thiophene (T) or selenophene (Se) serve as electron donors. Alternating polymers are synthesized through Stille cross-coupling, and their thermal stability, optical and electrochemical properties, field-effect carrier mobilities, film crystallinities, and photovoltaic performances are investigated. The intramolecular charge transfer between the electron-donating and electron-accepting units in the backbone induces absorption from 450 to 750 nm. The optical band-gap energies of the polymers are between 1.65 and 1.73 eV, and depend on the polymer structure. Organic photovoltaic cells fabricated using a polymer composed of DFQX and selenophene (PSe-DFQX) exhibit a power conversion efficiency of 5.14% with an open-circuit voltage of 0.78 V, a short-circuit current density of 11.71 mA/cm2, and fill factor of 0.57 under AM 1.5 G irradiation (100 mW cm−2). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1904-1914 [ABSTRACT FROM AUTHOR]

ABSTRACT Two donor-acceptor conjugated polymers, PTSSO-TT and PTSSO-BDT, composed of acenaphtho[1,2-c]thiophene -S,S-dioxide (TSSO) as a new electron acceptor and thienothiophene (TT) or benzo[1,2-b:4,5-b']dithiophene (BDT) as electron donors, were synthesized with Stille cross-coupling reactions. The number-averaged molecular weights ( Mn) of PTSSO-TT and PTSSO-BDT were found to be 15100 and 26000 Da, with dispersity of 1.8 and 2.4, respectively. The band-gap energies of PTSSO-TT and PTSSO-BDT are 1.56 and 1.59 eV, respectively. The HOMO levels of PTSSO-TT and PTSSO-BDT are −5.4 and −5.5 eV, respectively. These results indicate that the inclusion of TSSO accepting units into polymers is a very effective method for lowering their HOMO energy levels. The field-effect mobilities of PTSSO-TT and PTSSO-BDT were determined to be 1.5 × 10−3 and 4.5 × 10−4 cm2 V−1 s−1, respectively. A polymer solar cell device prepared with PTSSO-TT as the active layer was found to exhibit a power conversion efficiency (PCE) of 3.79% with an open circuit voltage of 0.71 V under AM 1.5 G (100 mW cm−2) conditions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 498-506 [ABSTRACT FROM AUTHOR]