Photoconductivity and small-polaron effects in tetracyanoquinodimethan

A. A. Bright, P. M. Chaikin, A. R. McGhie

    Research output: Contribution to journalArticle

    Abstract

    Photoconductivity has been observed in high-purity tetracyanoquinodimethan (TCNQ) single crystals and polycrystalline evaporated thin films. The photocurrent was measured as a function of wavelength, light intensity, and temperature. A photoconducting edge is observed at about 1.7 eV. The spectral response of the crystals and films are essentially identical. Comparison with optical-absorption, reflection, and resistivity data imply that the 1.7-eV edge is a measurement of the band gap. The relatively small value is attributed to the high electron affinity of TCNQ and its polaron binding energy. Pulsed photocurrent measurements give a drift mobility for both electrons and holes of about 0.4 cm2/V sec in single crystals and somewhat lower in thin films. The electron mobility is about 10% higher than the hole mobility, and both are independent of temperature from 204 to 306 °K. The results suggest that conduction occurs by diffusion of small polarons in a conduction band whose width is comparable to the phonon energies. The relevance of this study to other systems is discussed.

    Original languageEnglish (US)
    Pages (from-to)3560-3568
    Number of pages9
    JournalPhysical Review B
    Volume10
    Issue number8
    DOIs
    StatePublished - 1974

    Fingerprint

    Gene Conversion
    Photoconductivity
    Photocurrents
    photoconductivity
    photocurrents
    Single crystals
    Thin films
    Polarons
    Electron affinity
    Hole mobility
    Electron mobility
    single crystals
    hole mobility
    polarons
    thin films
    electron affinity
    Conduction bands
    Binding energy
    spectral sensitivity
    electron mobility

    ASJC Scopus subject areas

    • Condensed Matter Physics

    Cite this

    Photoconductivity and small-polaron effects in tetracyanoquinodimethan. / Bright, A. A.; Chaikin, P. M.; McGhie, A. R.

    In: Physical Review B, Vol. 10, No. 8, 1974, p. 3560-3568.

    Research output: Contribution to journalArticle

    Bright, A. A. ; Chaikin, P. M. ; McGhie, A. R. / Photoconductivity and small-polaron effects in tetracyanoquinodimethan. In: Physical Review B. 1974 ; Vol. 10, No. 8. pp. 3560-3568.
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