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Proceedings Paper

Charge carrier mobility in highly ordered smectic and discotic mesophases
Author(s): A. Pecchia; L. Siebbeles; Bijan Movaghar
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Paper Abstract

The recently published data on phototransit signals in smectic and discotic liquid crystals, have led us to reconsider the old problem of the weak temperature dependence of the mobility in ordered narrow band systems and inthe liquid crystalline phases. We argue that one has to distinguish between currents which are due to light-generated carriers and currents due to band conduction in equilibrium and which can be described using the Kubo-Greenwood formula. We use a first principle band model in an electric field and show how a T-independent mobility can be derived for a single particle which obeys band transport, includes joule energy relaxation, elastic disorder, and agrees with the few carrrier limit of the Kubo formula. The result is essentially a generalized Drude velocity applicable to describe "single particle currents". We also discuss alternative explanations for the observed temperature independent mobilities which are based on hopping with weak disorder and polaron theories.

Paper Details

Date Published: 14 July 2003
PDF: 21 pages
Proc. SPIE 4991, Organic Photonic Materials and Devices V, (14 July 2003); doi: 10.1117/12.478359
Show Author Affiliations
A. Pecchia, Univ. of Rome Tor Vergata (Italy)
L. Siebbeles, Delft Univ. of Technology (Netherlands)
Bijan Movaghar, Univ. of Leeds (United Kingdom)

Published in SPIE Proceedings Vol. 4991:
Organic Photonic Materials and Devices V
James G. Grote; Toshikuni Kaino, Editor(s)

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