Charge-Carrier Transport in Liquid-Crystal Based Organic Photoconductors

概要

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In this work we have used a one-dimensional model which incorporates energetic disorder to analyse the anomalous temperature dependence of the charge-carrier mobility in the liquid crystalline discotic twin HPAT_2 and the broadening of the photocurrent decays. In order to render tha main ideas as transparent as possible we have aimed at the simplest possible description which still includes the basic features. The model allows a closed-form expression for the Laplace transformed photocurrent. The temperature dependence of charge-carrier mobility can simply be calculated analytically if assuming a boxlike trap distribution. Assuming a temperature dependent trap parameter we could model the anomalous temperature dependence of charge-carrier mobilities. This temperature dependent dependent peculiarity of the trap distribution is inferred from the temperature dependent molecular dynamics in the D_h phase, as concluded from X-ray measurements and NMR experiments. A 'parellel connection' of different types of columns with different characteristic trap distributions could reproduce the broadened decay of photocurrent transients. The parallel connection was concluded from a homeotropic polydomain texture as seen in the polarizing microscope.
社団法人応用物理学会の論文
1996-03-15