Cyclopentadithiophene-benzothiadiazole oligomers and polymers; Synthesis, characterisation, field-effect transistor and photovoltaic characteristics

Masaki Horie, Jeff Kettle, Chin Yang Yu, Leszek A. Majewski, Shu Wei Chang, James Kirkpatrick, Sachetan M. Tuladhar, Jenny Nelson, Brian R. Saunders, Michael L. Turner

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Conjugated oligomers with various ratios of cyclopentadithiophene (CPDT) to benzothiadiazole (BT) repeating units are reported. These oligomers can be polymerised to high molecular weight polymers (M n > 100k) by oxidative polymerisation using iron(iii)chloride. The electronic properties of these materials were examined by cyclic voltammetry and UV-vis spectroscopy and the results compared to those calculated using density functional theory (DFT). Polymers with optimum ratios of CPDT:BT (2:1) units show hole mobilities in excess of 10 -2 cm 2 V -1 s -1 as the active layer in organic field effect transistors (OFETs). Bulk heterojunction organic photovoltaic (OPV) devices of these polymers with PCBM as the electron acceptor show a power conversion efficiency of 2.1% when processed in the absence of any additives. The reported OFET performance is significantly higher than the parent PCPDTBT alternating copolymer (CPDT:BT = 1:1) and also shows a moderate improvement in OPV performance. © 2012 The Royal Society of Chemistry.
    Original languageEnglish
    Pages (from-to)381-389
    Number of pages8
    JournalJournal of Materials Chemistry
    Volume22
    Issue number2
    DOIs
    Publication statusPublished - 14 Jan 2012

    Keywords

    • cyclopentadithiophene benzothiadiazole oligomer polymer synthesis field effect transistor

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