A comparative study of photoconductivity and carrier transport in oligomeric films

S. Reynolds, J. T. Shepherd, C. Main, J. M. Marshall, J. M. Maud

    Research output: Contribution to journalArticle

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    Abstract

    DC conductivity and transient photoconductivity (TPC) measurements on 1 µm films of pentacene and thienylene-vinylene oligomers deposited by thermal evaporation (TE) and by laser ablation are reported. Conduction properties are found to be relatively insensitive to both chemical composition and deposition method. DC conductivity prefactor magnitudes of order 0.1 S cm-1, and the observation of field-dependent conduction, are indicative of hopping transport. In all formulations we observed a two-power-law photocurrent decay, consistent with transport initially by hopping down in energy in an exponential distribution of localised states followed by thermal excitation and multiple-trapping (MT). The temperature-dependence of photocurrent decay has been studied for pentacene and yields an exponential tail slope of 650 K (56 meV). A maximum mobility of 10-5 cm2 V-1 s-1 is estimated from the TPC data, 2–3 orders less than field-effect mobilities reported previously. This discrepancy may be due to differences between surface and interior conduction processes.

    Original languageEnglish
    Pages (from-to)994-998
    Number of pages5
    JournalJournal of Non-Crystalline Solids
    Volume266
    Issue number2
    DOIs
    Publication statusPublished - May 2000

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    Carrier transport
    Photoconductivity
    Photocurrents
    photoconductivity
    conduction
    photocurrents
    Thermal evaporation
    Laser ablation
    direct current
    Oligomers
    conductivity
    decay
    oligomers
    laser ablation
    chemical composition
    Chemical analysis
    trapping
    evaporation
    slopes
    formulations

    Cite this

    Reynolds, S. ; Shepherd, J. T. ; Main, C. ; Marshall, J. M. ; Maud, J. M. / A comparative study of photoconductivity and carrier transport in oligomeric films. In: Journal of Non-Crystalline Solids. 2000 ; Vol. 266, No. 2. pp. 994-998.
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    abstract = "DC conductivity and transient photoconductivity (TPC) measurements on 1 µm films of pentacene and thienylene-vinylene oligomers deposited by thermal evaporation (TE) and by laser ablation are reported. Conduction properties are found to be relatively insensitive to both chemical composition and deposition method. DC conductivity prefactor magnitudes of order 0.1 S cm-1, and the observation of field-dependent conduction, are indicative of hopping transport. In all formulations we observed a two-power-law photocurrent decay, consistent with transport initially by hopping down in energy in an exponential distribution of localised states followed by thermal excitation and multiple-trapping (MT). The temperature-dependence of photocurrent decay has been studied for pentacene and yields an exponential tail slope of 650 K (56 meV). A maximum mobility of 10-5 cm2 V-1 s-1 is estimated from the TPC data, 2–3 orders less than field-effect mobilities reported previously. This discrepancy may be due to differences between surface and interior conduction processes.",
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    A comparative study of photoconductivity and carrier transport in oligomeric films. / Reynolds, S.; Shepherd, J. T.; Main, C.; Marshall, J. M.; Maud, J. M.

    In: Journal of Non-Crystalline Solids, Vol. 266, No. 2, 05.2000, p. 994-998.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - A comparative study of photoconductivity and carrier transport in oligomeric films

    AU - Reynolds, S.

    AU - Shepherd, J. T.

    AU - Main, C.

    AU - Marshall, J. M.

    AU - Maud, J. M.

    PY - 2000/5

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    N2 - DC conductivity and transient photoconductivity (TPC) measurements on 1 µm films of pentacene and thienylene-vinylene oligomers deposited by thermal evaporation (TE) and by laser ablation are reported. Conduction properties are found to be relatively insensitive to both chemical composition and deposition method. DC conductivity prefactor magnitudes of order 0.1 S cm-1, and the observation of field-dependent conduction, are indicative of hopping transport. In all formulations we observed a two-power-law photocurrent decay, consistent with transport initially by hopping down in energy in an exponential distribution of localised states followed by thermal excitation and multiple-trapping (MT). The temperature-dependence of photocurrent decay has been studied for pentacene and yields an exponential tail slope of 650 K (56 meV). A maximum mobility of 10-5 cm2 V-1 s-1 is estimated from the TPC data, 2–3 orders less than field-effect mobilities reported previously. This discrepancy may be due to differences between surface and interior conduction processes.

    AB - DC conductivity and transient photoconductivity (TPC) measurements on 1 µm films of pentacene and thienylene-vinylene oligomers deposited by thermal evaporation (TE) and by laser ablation are reported. Conduction properties are found to be relatively insensitive to both chemical composition and deposition method. DC conductivity prefactor magnitudes of order 0.1 S cm-1, and the observation of field-dependent conduction, are indicative of hopping transport. In all formulations we observed a two-power-law photocurrent decay, consistent with transport initially by hopping down in energy in an exponential distribution of localised states followed by thermal excitation and multiple-trapping (MT). The temperature-dependence of photocurrent decay has been studied for pentacene and yields an exponential tail slope of 650 K (56 meV). A maximum mobility of 10-5 cm2 V-1 s-1 is estimated from the TPC data, 2–3 orders less than field-effect mobilities reported previously. This discrepancy may be due to differences between surface and interior conduction processes.

    U2 - 10.1016/S0022-3093(99)00891-1

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    M3 - Article

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    JF - Journal of Non-Crystalline Solids

    SN - 0022-3093

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    ER -