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Low Bandgap (low + bandgap)
Selected AbstractsLow bandgap ,-conjugated copolymers based on fused thiophenes and benzothiadiazole: Synthesis and structure-property relationship studyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Shiming Zhang Abstract A series of low bandgap conjugated polymers consisting of benzothiadiazole alternating with dithienothiophene (DTT) or dithienopyrrole (DTP) unit with or without 3-alkylthiophene bridge have been synthesized. Effect of the fused rings and 3-alkylthiophene bridge on the thermal, optical, electrochemical, charge transport, and photovoltaic properties of these polymers have been investigated. These polymers show broad absorption extending from 300 to 1000 nm with optical bandgaps as low as 1.2 eV; the details of which can be varied either by incorporating 3-alkylthiophene bridge or by replacing DTT with DTP. The LUMO levels (,2.9 to ,3.3 eV) are essentially unaffected by the specific choice of donor moiety, whereas the HOMO levels (,4.6 to ,5.6 eV) are more sensitive to the choice of donor. The DTT and DTP polymers with 3-alkylthiophene bridge were found to exhibit hole mobilities of 8 × 10,5 and 3 × 10,2 cm2 V,1 s,1, respectively, in top-contact organic field-effect transistors. Power conversion efficiencies in the range 0.17,0.43% were obtained under simulated AM 1.5, 100 mW cm,2 irradiation for polymer solar cells using the DTT and DTP-based polymers with 3-alkylthiophene bridge as donor and fullerene derivatives as acceptor. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5498,5508, 2009 [source] Highly Emissive and Electrochemically Stable Thienylene Vinylene Oligomers and Copolymers: An Unusual Effect of Alkylsulfanyl SubstituentsADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Shehzad Jeeva Abstract The synthesis, unexpected efficient photoluminescence, and reversible electrochemical p- and n-doping of new conjugated thienylene vinylene materials functionalized with alkylsulfanyl substituents poly(trithienylene vinylene) (PTTV) and poly(dithienylvinyl- co -benzothiadiazole) (PDTVB) along with dithienylvinylene-based oligomers is reported. The materials are studied by thermal and X-ray diffraction analysis, optical spectroscopy, cyclic voltammetry, and spectroelectrochemistry. Organic field-effect transistors (OFETs) are fabricated with PTTV and PDTVB. The polymers, prepared by Stille polycondensation, exhibit good thermal stability and a photoluminescent quantum yield in the range 34%,68%. Low bandgaps (1.5,1.8,eV), estimated by optical and electrochemical measurements along with high stability of both redox states, suggest that these structures are promising materials for photovoltaic applications. OFETs fabricated with PDTVB reveal a hole mobility of 7,×,10,3,cm2 V,1 s,1 with on/off ratio 105, which are comparatively high values for completely amorphous polymer semiconductors. [source] Low bandgap ,-conjugated copolymers based on fused thiophenes and benzothiadiazole: Synthesis and structure-property relationship studyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Shiming Zhang Abstract A series of low bandgap conjugated polymers consisting of benzothiadiazole alternating with dithienothiophene (DTT) or dithienopyrrole (DTP) unit with or without 3-alkylthiophene bridge have been synthesized. Effect of the fused rings and 3-alkylthiophene bridge on the thermal, optical, electrochemical, charge transport, and photovoltaic properties of these polymers have been investigated. These polymers show broad absorption extending from 300 to 1000 nm with optical bandgaps as low as 1.2 eV; the details of which can be varied either by incorporating 3-alkylthiophene bridge or by replacing DTT with DTP. The LUMO levels (,2.9 to ,3.3 eV) are essentially unaffected by the specific choice of donor moiety, whereas the HOMO levels (,4.6 to ,5.6 eV) are more sensitive to the choice of donor. The DTT and DTP polymers with 3-alkylthiophene bridge were found to exhibit hole mobilities of 8 × 10,5 and 3 × 10,2 cm2 V,1 s,1, respectively, in top-contact organic field-effect transistors. Power conversion efficiencies in the range 0.17,0.43% were obtained under simulated AM 1.5, 100 mW cm,2 irradiation for polymer solar cells using the DTT and DTP-based polymers with 3-alkylthiophene bridge as donor and fullerene derivatives as acceptor. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5498,5508, 2009 [source] Novel two-dimensional donor,acceptor conjugated polymers containing quinoxaline units: Synthesis, characterization, and photovoltaic propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2008Lijun Huo Abstract Novel two-dimensional donor,acceptor (D,A) structured conjugated polymers, P1,P4, were designed and synthesized by introducing electron-deficient quinoxaline as core and electron-rich alkoxyl-phenylenevinylene in side chains and p -phenylenevinylene, triphenylamine, or thiophene in main chain. Benefited from the D,A structures, the polymers possess low bandgaps of 1.75 eV, 1.86 eV, 1.59 eV, and 1.58 eV for P1, P2, P3, and P4, respectively, and show broad absorption band in the visible region: the shorter wavelength absorption peak at ,400 nm ascribed to the conjugated side chains and the longer wavelength absorption peak between 500 nm and 750 nm belonging to the absorption of the conjugated main chains. Especially, the absorption band of P4 film covers the whole visible range from 300 nm to 784 nm. The power conversion efficiencies of the polymer solar cells based on P1,P4 as donor and PCBM as acceptor are 0.029%, 0.14%, 0.46%, and 0.57%, respectively, under the illumination of AM 1.5, 100 mW/cm2. The polymers with the low bandgap and broad absorption band are promising photovoltaic materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4038,4049, 2008 [source] | ||||||||||