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Nondispersive hole transport of liquid crystalline glasses and a cross-linked network for organic electroluminescence

2002; American Physical Society; Volume: 66; Issue: 12 Linguagem: Inglês

10.1103/physrevb.66.125107

1095-3795

S. R. Farrar, Adam E. A. Contoret, Mary O’Neill, J.E. Nicholls, Gary J. Richards, Stephen M. Kelly,

Photonic Crystals and Applications

Photocurrent time-of-flight experiments are used to study the transport properties of hole-conducting nematic liquid crystals. Nondispersive transients are observed and a value of $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}{\mathrm{cm}}^{2}{\mathrm{V}}^{\ensuremath{-}1}{\mathrm{s}}^{\ensuremath{-}1}$ is found for the hole mobility of a chiral nematic glass at room temperature. The hole mobility of a reactive mesogen in the nematic glass phase is increased by photopolymerization of its reactive end chains to form an insoluble network. The mobility of the network shows a weak field dependence over the temperature range 295--373 K. The experimental data can be explained by hopping between the nematic cores using a Gaussian disorder model that includes spatial correlations in the carrier energy. The density-of-state distribution obtained from the model agrees with that measured spectroscopically.