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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. 2015

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

A “zigzag” naphthodithiophene-based copolymer, poly[4,9-bis(2-ethylhexyloxy)naphtho[1,2-b:5,6-b′]dithiophene-2,7-diyl-alt-1,3-(5-heptadecan-9-yl)-4H-thieno[3,4-c]pyrrole-4,6-dione] (P1) is synthesized and its properties are compared to “linear” naphthodithiophene-based copolymer, poly[4,9-bis(2-ethylhexyloxy)naphtho[2,3-b:6,7-d′]dithiophene-2,7-diyl-alt-1,3-(5-heptadecan-9-yl)-4H-thieno[3,4-c]pyrrole-4,6-dione] (P2). The field-effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers are systematically investigated. The results suggest that the backbone of the copolymer structure significantly influences the band gap, electronic energy levels, carrier mobilities, and photovoltaic properties of the resultant thin films. In this work, the zigzag naphtho[1,2-b:5,6-b′]dithiophene-based copolymer displays a good hole mobility and a high open-circuit voltage; however, polymer solar cells in which the linear naphtho[2,3-b;6,7-d′]dithiophene-based copolymer is used as the electron donor material perform better than the cells prepared using the zigzag naphtho[1,2-b:5,6-b′]dithiophene-based copolymer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 305–312

A series of new donor–acceptor-type low-band-gap semiconducting polymers were synthesized as electron donors for organic photovoltaic cells. The polymers comprised quinoxaline derivatives as the acceptors and a benzodithiophene (BDT) derivative as the donors. 5,8-Dibromoquinoxaline (Qx), 8,11-dibromobenzo[a]phenazine (BPz), 10,13-dibromodibenzo[a,c]phenazine (DBPz), and 8,11-dibromo-5-(9H-carbazol-9-yl)benzo[a]phenazine) (CBPz) were synthesized and polymerized with 2,6-bis(trimethyltin)−4,8-diethylhexyloxybenzo-[1,2-b;3,4-b]dithiophene (BDT) through Stille cross-coupling to produce four types of fully conjugated semiconducting polymers: PBDT-Qx, PBDT-BPz, PBDT-DBPz, and PBDT-CBPz, respectively. Intramolecular charge transfer between the electron donating and accepting units in the polymeric backbone induced a broad absorption from 300 to 800 nm. The optical band gap energies of the polymers were measured from their absorption onsets to be 1.54–1.80 eV depending on the polymer structure. Solution-processed field-effect transistors were fabricated to measure the hole mobilities of the polymers, and bulk hetero-junction photovoltaic devices were fabricated using the synthesized polymers as electron donors and fullerene derivatives as electron acceptors. One of these devices showed a high power conversion efficiency of 3.87% with an open-circuit voltage of 0.78 V, a short-circuit current of 9.68 mA/cm2, and a fill factor of 0.51 under air mass 1.5 global (AM 1.5 G) illumination conditions (100 mW/cm2). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4136–4149

Three new polymers poly(3,4′′′-didodecyl) hexaselenophene) (P6S), poly(5,5′-bis(4,4′-didodecyl-2,2′-biselenophene-5-yl)-2,2′-biselenophene) (HHP6S), and poly(5,5′-bis(3′,4-didodecyl-2,2′-biselenophene-5-yl)-2,2′-biselenophene) (TTP6S) that have the same selenophene-based polymer backbone but different side chain patterns were designed and synthesized. The weight-averaged molecular weights (Mw) of P6S, HHP6S, and TTP6S were found to be 19,100, 24,100, and 19,700 with polydispersity indices of 2.77, 1.48, and 1.41, respectively. The UV–visible absorption maxima of P6S, HHP6S, and TTP6S are at 524, 489, and 513 nm, respectively, in solution and at 569, 517, and 606 nm, respectively, in the film state. The polymers P6S, HHP6S, and TTP6S exhibit low band gaps of 1.74, 1.95, and 1.58 eV, respectively. The field-effect mobilities of P6S, HHP6S, and TTP6S were measured to be 1.3 × 10−4, 3.9 × 10−6, and 3.2 × 10−4 cm2 V−1 s−1, respectively. A photovoltaic device with a TTP6S/[6,6]-phenyl C71-butyric acid methyl ester (1:3, w/w) blend film active layer was found to exhibit an open circuit voltage (VOC) of 0.71 V, a short circuit current (JSC) of 5.72 mA cm−2, a fill factor of 0.41, and a power conversion efficiency (PCE) of 1.67% under AM 1.5 G (100 mW cm−2) illumination. TTP6S has the most planar backbone of the tested polymers, which results in strong π–π interchain interactions and strong aggregation, leading to broad absorption, high mobility, a low band gap, and the highest PCE. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Condensation copolymerization reactions of carbazole 3,6-diboronate with 4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole (DTBT) only produce low-molecular-weight donor (D)-π-acceptor (A) copolymers. High-molecular-weight copolymers for use in optoelectronic devices are necessary for achieving extended π-conjugation and for controlling the copolymer processibility. To elucidate the cause of the persistently low molecular weight, we synthesized three 3,6-carbazole-based D-A copolymers using copolymerizations of N-9′-heptadecanyl-3,6-carbazole with DTBT, N-9′{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethyl}-3,-6-carbazole with DTBT, and N-9′-heptadecanyl-3,6-carbazole with alkyl-substituted DTBT. We investigated several parameters for their influence on molecular copolymer weight, including the conformation of the chain during growth, the solubility of the monomers, and the dihedral angles between the donor and acceptor units. Size exclusion chromatography, UV–vis absorption spectroscopy, and computational studies revealed that the low molecular weights of 3,6-carbazole-based D-A copolymers resulted from conjugation breaks and the resulting high coplanarity, which led to strong interactions between polymer chains. These interactions limited formation of high-molecular-weight-copolymers during copolymerization. The strong intermolecular interactions of the 3,6-carbazole moiety were exploited by incorporating 3,6-carbazole units into poly[9′,9′-dioctyl-2,7-flourene-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] prepared from 9′,9′-dioctyl-2,7-flourene and DTBT. Interestingly, the number average molecular weight increased gradually with increasing 2,7-fluorene monomer content but the number of conjugation breaks was a range of 6–7. The hole mobilities of the copolymers were studied for comparison purposes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A novel series of thiazolothiazole (Tz)-based copolymers, poly[9,9-didecylfluorene-2,7-diyl-alt-2,5-bis-(3-hexylthiophene-2-yl)thiazolo[5,4-d]thiazole] (P1), poly[9,9-dioctyldibenzosilole-2,7-diyl-alt-2,5-bis-(3-hexylthiophene-2-yl)thiazolo[5,4-d]thiazole] (P2), and poly[4,4′-bis(2-ethylhexyl)-dithieno[3,2-b:2′,3′-d]silole-alt-2,5-bis-(3-hexylthiophene-2-yl)thiazolo[5,4-d]thiazole] (P3), were synthesized for the use as donor materials in polymer solar cells (PSCs). The field-effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers were investigated. The results suggest that the donor units in the copolymers significantly influenced the band gap, electronic energy levels, carrier mobilities, and photovoltaic properties of the copolymers. The band gaps of the copolymers were in the range of 1.80–2.14 eV. Under optimized conditions, the Tz-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range of 2.23–2.75% under AM 1.5 illumination (100 mW/cm2). Among the three copolymers, P1, which contained a fluorene donor unit, showed a PCE of 2.75% with a short-circuit current of 8.12 mA/cm2, open circuit voltage of 0.86 V, and a fill factor (FF) of 0.39, under AM 1.5 illumination (100 mW/cm2). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A series of new phenothiazylene vinylene-based semiconducting polymers, poly[3,7-(4′-dodecyloxyphenyl)phenothiazylene vinylene] (P1), poly[3,7-(4′-dodecyloxyphenyl)phenothiazylene vinylene-alt-1,4-phenylene vinylene] (P2), and poly[3,7-(4′-dodecyloxyphenyl)phenothiazylene vinylene-alt-2,5-thienylene vinylene] (P3), have been synthesized via a Horner-Emmons reaction. FTIR and 1H NMR spectroscopies confirmed that the configurations of the vinylene groups in the polymers were all-trans (E). The weight-averaged molecular weights (Mw) of P1, P2, and P3 were found to be 27,000, 22,000, and 29,000, with polydispersity indices of 1.91, 2.05, and 2.25, respectively. The thermograms for P1, P2, and P3 each contained only a broad glass transition, at 129, 167, and 155 °C, respectively, without the observation of melting features. UV–visible absorption spectra of the polymers showed two strong absorption bands in the ranges 315–370 nm and 450–500 nm, which arose from absorptions of the phenothiazine segments and the conjugated main chains. Solution-processed field-effect transistors fabricated from these polymers showed p-type organic thin-film transistor characteristics. The field-effect mobilities of P1, P2, and P3 were measured to be 1.0 × 10−4, 3.6 × 10−5, and 1.0 × 10−3 cm2 V−1 s−1, respectively, and the on/off ratios were in the order of 102 for P1 and P2, and 103 for P3. Atomic force microscopy and X-ray diffraction analysis of thin films of the polymers show that they have amorphous structures. A photovoltaic device in which a P3/PC71BM (1/5) blend film was used as the active layer exhibited an open-circuit voltage (VOC) of 0.42 V, a short circuit current (JSC) of 5.17 mA cm−2, a fill factor of 0.35, and a power conversion efficiency of 0.76% under AM 1.5 G (100 mW cm−2) illumination. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 635–646, 2010

We synthesized a novel low-band-gap, conjugated polymer, poly[4,7-bis(3′,3′-diheptyl-3,4-propylenedioxythienyl)-2,1,3-benzothiadiazole] [poly(heptyl4-PTBT)], consisting of alternating electron-rich, diheptyl-substituted propylene dioxythiophene and electron-deficient 2,1,3-benzothiadiazole units, and its photovoltaic properties were investigated. A thin film of poly(heptyl4-PTBT) exhibited an optical band gap of 1.55 eV. A bulk-heterojunction solar cell with indium tin oxide/poly(3,4-ethylenedioxythiophene)/poly(heptyl4-PTBT): methanofullerene [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:4)/LiF/Al was fabricated with poly(heptyl4-PTBT) as an electron donor and PCBM as an electron acceptor and showed an open-circuit voltage, short-circuit current density, and power conversion efficiency of 0.37 V, 3.15 mA/cm2, and 0.35% under air mass 1.5 (AM1.5G) illumination (100 mW/cm2), respectively. A solid-state, dye-sensitized solar cell with a SnO2:F/TiO2/N3 dye/poly(heptyl4-PTBT)/Pt device was fabricated with poly(heptyl4-PTBT) as a hole-transport material. This device exhibited a high power conversion efficiency of 3.1%, which is the highest power conversion efficiency value with hole-transport materials in dye-sensitized solar cells to date. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1394–1402, 2007

A new series of copolymers with high brightness and luminance efficiency were synthesized using the Gilch polymerization method, and their electro-optical properties were investigated. The weight-average molecular weights (Mw) and polydispersities of the synthesized poly(9,9-dioctylfluorenyl-2,7-vinylene) [poly(FV)], poly[2-(3-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] [poly(m-SiPhPV)], and poly[9,9-di-n-octylfluorenyl-2,7-vinylene]-co-(2-(3-dimethyldodecylsilylphenyl)-1,4-phenylene vinylene)] [poly(FV-co-m-SiPhPV)] were found to be in the ranges of (8.7–32.6) × 104 and 2.3–5.4, respectively. It was found that the electro-optical properties of the copolymers could be adjusted by controlling the feed ratios of the comonomers. Thin films of poly(FV), poly(m-SiPhPV), and poly(FV-co-m-SiPhPV) were found to exhibit photoluminescence quantum yields between 21% and 42%, which are higher than those of MEH-PPV. Light-emitting diodes were fabricated in ITO/PEDOT/light-emitting polymer/cathode configurations using either double layer (LiF/Al) or triple layer (Alq3/LiF/Al) cathode structures. The performance of the polymer light-emitting diodes (PLEDs) with triple layer cathodes was found to be better than that of the PLEDs with double layer cathodes in poly(FV) and poly(FV-co-m-SiPhPV). The turn-on voltages of the PLEDs were in the range of 4.5–6.0 V, with maximum brightness and luminance efficiency up to 9691 cd/m2 at 16 V and 3.27 cd/A at 13 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5062–5071, 2005

The reaction of nitroethylene with isobutyl vinyl ether was reinvestigated. In agreement with the report of Kushibiki, Irie, and Hayashi (J Polym Sci Polym Chem Ed 1975, 13, 77), cycloaddition accompanied the anionic homopolymerization of nitroethylene. However, the cycloadduct was not a cyclobutane but a bicyclic oxazolidine, in keeping with the more recent report by Denmark and Hurd (J Org Chem 1998, 63, 3045). Cycloaddition accompanied by the anionic homopolymerization of nitroethylene was general for a series of vinyl and silyl ethers. Mechanistically, the cycloadducts formed by a cis–syn concerted approach of the reactants, whereas a trans–anti approach gave a zwitterionic tetramethylene that initiated anionic homopolymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1886–1891, 2001