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Transport Properties of Highly Aligned Polymer Light-Emitting-Diodes

A. Kambili·A. B. Walker
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Abstract

We investigate hole transport in polymer light-emitting-diodes in which the emissive layer is made of liquid-crystalline polymer chains aligned perpendicular to the direction of transport. Calculations of the current as a function of time via a random-walk model show excellent qualitative agreement with experiments conducted on electroluminescent polyfluorene demonstrating non-dispersive hole transport. The current exhibits a constant plateau as the charge carriers move with a time-independent drift velocity, followed by a long tail when they reach the collecting electrode. Variation of the parameters within the model allows the investigation of the transition from non-dispersive to dispersive transport in highly aligned polymers. It turns out that large inter-chain hopping is required for non-dispersive hole transport and that structural disorder obstructs the propagation of holes through the polymer film.

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A. Kambili, A. B. Walker. 2000-07-10. Transport Properties of Highly Aligned Polymer Light-Emitting-Diodes. https://doi.org/10.1103/physrevb.63.012201

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