Charge transport in tri-p-tolylamine doped trinaphthalylbenzene glass

The charge transport properties of tri-p-tolylamine (TTA) doped trinaphthal ylbenzene have been measured as a function of electric field and temperatur e. The charge mobilities of the composite are comparable to but somewhat lo wer than that of TTA doped polystyrene, a nonpolar polymeric host, at simil ar weight fractions. We suggest that the difference is due to inhomogeneity between the host and the dopant. The results suggest that, similar to poly mer hosts in molecularly doped polymers, the molecular host only functions as an inert diluter and does not directly participate in the charge transpo rt manifold. The results also substantiate the importance of molecular pack ing to charge hopping in disordered organic materials. The charge mobility data are analyzed with a disorder model due to Bassler and coworkers and a recently modified expression due to Novikov and coworkers [Phys. Rev. Lett. 81, 4472 (1998)]. Both models provide adequate descriptions of charge tran sport in organic amorphous materials. (C) 2000 American Institute of Physic s. [S0021-8979(00)08519-4].