Poly[(3-hexyliminomethyl)thiophene]s (P3HITs) were synthesized from the polymerizations of 2,5-dibromo-(hexyliminomethyl)thiophene and 5-bromo-2-iodo-3-(hexyliminomethyl)thiophene by Grignard metathesis method. The corresponding P3HITs with low regioregularity (70%) and high regioregularity (95%) were obtained, respectively. UV-vis and photoluminescence spectra of P3HIT were dependent on the regioregularity and solvent polarity. By hydrolysis of the imino groups in the side chains under acidic conditions, P3HIT was successfully converted into the polythiophene (P3TCHO) having aldehyde groups. This transformation was also performed facilely by exposing the P3HIT film to HCl gas to give the polythiophene having aldehyde moiety. The reverse way from aldehyde to imine was also successfully demonstrated by treating the film with triethylamine vapor. V

Abstractπ‐Conjugated polymers, PBDT‐CNETT and PBDT‐CNECPDT, were prepared by the Stille cross‐coupling polymerization. Optical and thermal properties of the obtained polymers were investigated by UV–vis spectroscopy and thermogravimetric analysis. PBDT‐CNETT and PBDT‐CNECPDT exhibited very narrow band gaps of 1.39 and 1.13 eV, respectively. Highest occupied molecular orbital energy levels estimated by surface analyzer were −5.17 and −5.11 eV for PBDT‐CNETT and PBDT‐CNECPDT, respectively. The solar cells based on these polymers were evaluated with the cell configuration of ITO/PEDOT‐PSS/polymer:PC61BH/LiF/Al. The power conversion efficiencies of the solar cells were estimated to be 1.57 and 0.16% for PBDT‐CNETT and PBDT‐CNECPDT, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

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Soluble polythiophenes bearing strong electron withdrawing groups, dicyanoethenyl [ACH¼ ¼C(CN) 2 ] (PTDCN) and cyano-methoxycarbonylethenyl [ACH¼ ¼C(CO 2 Me)CN] (PTCNME), in the side chains have been prepared. Optical band gaps calculated from onset absorption were 1.70 eV and 1.73 eV for PTDCN and PTCNME, respectively. Highest occupied molecular orbital energy levels measured with a surface analyzer (AC-2) were À5.53 eV and À5.29 eV for PTDCN and PTCNME, respectively, which were much lower than that of poly(3-hexylthiophene) (À4.81 eV). To investigate photovoltaic properties, bulk heterojunction polymer solar cells based on PTDCN and PTCNME were fabricated with a structure of ITO/ PEDOT:PSS/active layer/LiF/Al, where the active layer was a blend film of polymer and [6,6]-phenyl C 61 butyric acid hexyl ester (PC 61 BH). Solar cell parameters were estimated from current density-voltage (J-V) characteristics under the illumination of AM1.5 at 100 mW/cm 2 . The solar cell based on the blend film of PTCNME:PC 61 BH (1:1) showed power conversion efficiency (PCE) of 0.72% together with the open current voltage (V oc ) of 0.61 V, the short current density (J sc ) of 3.90 mA/cm 2 , and the fill factor of 30.3%. The PCE of a solar cell fabricated from PTDCN in a similar way was 0.56%. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [234][235][236][237][238][239][240][241] 2011

π‐Conjugated polymers, PTOTBT, PTEHTBT, and PTt‐BTBT, composed of benzothiadiazole as an electron accepting unit and terthiophene as an electron donating unit in the backbone were prepared. PTOTBT, PTEHTBT, and PTt‐BTBT contained side chain groups of n‐octyl, 2‐ethylhexyl, and t‐butyl groups, respectively. Solubility, optical and thermal properties of the polymers showed strong dependences on their side chain groups. PTEHTBT having 2‐ethylhexyl groups in the side chain exhibited absorption maximum (λmax) at longer wavelength (565 nm) than PTOTBT (534 nm) and PTt‐BTBT (495 nm). PTOTBT showed higher thermal stability than the others. The prepared polymers were employed to polymer solar cells (PSCs) with a configuration of ITO/PEDOT‐PSS/polymer: PC61BH/LiF/Al. Power conversion efficiency of the PSC‐based on PTEHTBT was 1.32%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011