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Proceedings Paper

Charge relaxation and dynamics in organic semiconductors
Author(s): H. L. Kwok
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Paper Abstract

Charge relaxation in dispersive materials is often described in terms of the stretched exponential function (Kohlrausch law). The process can be explained using a "hopping" model which in principle, also applies to charge transport such as current conduction. This work analyzed reported transient photoconductivity data on functionalized pentacene single crystals using a geometric hopping model developed by B. Sturman et al and extracted values (or range of values) on the materials parameters relevant to charge relaxation as well as charge transport. Using the correlated disorder model (CDM), we estimated values of the carrier mobility for the pentacene samples. From these results, we observed the following: i) the transport site density appeared to be of the same order of magnitude as the carrier density; ii) it was possible to extract lower bound values on the materials parameters linked to the transport process; and iii) by matching the simulated charge decay to the transient photoconductivity data, we were able to refine estimates on the materials parameters. The data also allowed us to simulate the stretched exponential decay. Our observations suggested that the stretching index and the carrier mobility were related. Physically, such interdependence would allow one to demarcate between localized molecular interactions and distant coulomb interactions.

Paper Details

Date Published: 14 September 2006
PDF: 8 pages
Proc. SPIE 6320, Complex Photonic Media, 63200I (14 September 2006); doi: 10.1117/12.673715
Show Author Affiliations
H. L. Kwok, Univ. of Victoria (Canada)

Published in SPIE Proceedings Vol. 6320:
Complex Photonic Media
Graeme Dewar; Martin W. McCall; Mikhail A. Noginov; Nikolay I. Zheludev, Editor(s)

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