Jingmei Xu

Electrically conductive and fluorescent poly[1,4-bis(3-alkyl-2- thienyl)phenylenes]: syntheses and preliminary characterization aspects

Abstract A series of polymers containing alternating phenylene and symmetrically substituted bithiophene repeat units have been synthesized and characterized using UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, conductivity measurement and thermal analyses. The results reveal that the polymers have a bandgap energy of 2.5 eV and a fluorescence quantum yield of up to 26% with respect to quinine sulfate. The polymers show a maximum conductivity of 0.2 S cm −1 upon doping with I 2 and display good thermal stability in both neutral and doped states. The influence of alkyl chain size on conductivity, spectral behavior and thermal stability is discussed.

Regioregular poly[3-butyl-2,5-thienylene-alt-1,4-phenylene]: synthesis, preliminary characterization aspects and application in the fabrication of light-emitting diodes

A novel regioregular polymer comprising alternating 1,4-phenylene and 3-butyl-2,5-thienylene repeat units has been synthesized and characterized using 1 H NMR, FTIR, UV-VIS absorption and fluorescence emission spectroscopy. The derived polymer showed strong fluorescence with a solution quantum yield of 48% relative to quinine sulfate and a film phase photoluminescence yield of 17%. Green light-emitting diodes were fabricated using the polymer as the emitter layer.

Thermal stability and kinetic study of conductive polymers containing phenylene and bithiophene units

Abstract A series of conductive polymers containing alternating phenylene and substituted bithiophene repeat units was synthesized and studied using thermogravimetry (TG). Polymers with longer substituted alkyl chains exhibit lower thermal stability compared to those with shorter alkyl chains. Activation energies obtained by the Kissingers method gave support to this observation. Poly[1,4-bis(3-octyl-2-thienyl)phenylene] (PBTBC 8 ), one of the polymers in the series, was also studied under isothermal conditions and the activation energies obtained agreed quite well with those from dynamic TG. The thermal stability of polymers in the doped state was also studied and the adverse effect caused by dopant was less pronounced compared to the polyalkylthiophenes reported in the literature.

A new approach to the synthesis of substituted bithiophene and polymers containing thiophene

Abstract Palladium-catalyzed reaction of Bu 3 SnSnBu 3 with bromo-substituted thiophene or bromo-substituted thiophene-containing monomers is found to generate bithiophene or symmetric polymers containing thiophene in very good yields, respectively.

Polymers containing alternating 1,4-bis(3-octyl-2,5-thienylene)phenylene and 2,5-pyridyl, 4,4’-biphenylene or phenylene repeating units

Abstract Two polymers based on polymer backbone modification, poly[1,4-bis(3-octyl-2,5-thienylene)phenylene- alt -2,5-pyridyl] (PBTYC 8 ) and poly[1,4-bis(3-octyl-2,5-thienylene)phenylene- alt -4,4’-biphenylene] (PBTBBC 8 ), were synthesized and characterized in comparison with other two polymers reported earlier: poly[3-octyl-2,5-thienylene- alt -1,4-phenylene] (PBTC 8 ) and poly[1,4-bis(3-octyl-2-thienylene)phenylene] (PBTBC 8 ). PBTBBC 8 shows a lower conductivity in comparison with PBTC 8 and PBTBC 8 . A trend in absorption peak wavelength ( λ max ) of solution samples and in emission peak wavelength ( λ em ) of film samples is also noted for the polymers: PBTBBC 8 8 8 , with the decrease of phenylene content. The optical behavior of PBTYC 8 seems to suggest the existence of charge transfer (CT) and energy charge (ET) phenomenon due to the incorporation of electron-deficient pyridyl units. Interesting electrochemical observation is also obtained, which is supported directly by the spectral change measured in situ.