Transient photocurrents in a charge transfer complex of trinitrofluorenone with a carbazole substituted discotic liquid crystal |
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Authors: | K.J. Donovan K. Scott M. Somerton J. Preece M. Manickam |
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Affiliation: | 1. Physics Department, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom;2. School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom |
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Abstract: | We describe transient photoconduction studies on a well known triphenylene discotic liquid crystal molecule modified to incorporate a single carbazole moiety on one side chain and doped with the acceptor, trinitrofluorenone. This material is found to show both electron and hole photocurrents when the transient photoconduction study is carried out in the time of flight geometry although no time of flight transits are observed. Of interest here is the fact that the temperature dependence of the hole and electron photocurrents are radically different, the electron photocurrent being strongly activated while the hole photocurrent decreases with increasing temperature. We suggest a mechanism whereby the electron photocurrent controls the hole photocurrent through recombination. Furthermore, the electron activation energy varies with the applied electric field, indicating the influence of the Poole Frenkel barrier lowering mechanism in the production of the charge carriers. |
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Keywords: | Photoconduction Discotic liquid crystals Charge transfer complex Recombination |
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