HOLE TRANSPORT IN HYDRAZONE DOPED POLYMERS

Hole mobilities have been measured in poly(styrene) doped with a serie s of hydrazone (HDZ) molecules with different dipole moments. The resu lts are described by a formalism based on disorder. The formalism is p remised on the argument that charge transport occurs by hopping throug h a manifold of localized states that are distributed in energy. The p arameters of the formalism are sigma, the energy width of the hopping site manifold or DOS (density-of-states), mu(0) a prefactor mobility, and Sigma the degree of positional disorder. The results show that the widths are between 0.098 and 0.113eV, increasing with increasing dipo le moment. The widths are described by an argument based on dipolar di sorder. The argument is that the total width of the DOS is comprised o f a dipolar component and a van der Waals component. Describing the di polar component by the model of Young leads to the conclusion that the van der Waals components are approximately 0.091eV. The prefactor mob ilities are between 6 and 9 x 10(-3) cm(2)/Vs. Values of Sigma are app roximately 1.5. Compared to other classes of doped polymers with simil ar dipole moments, the relatively low mobilities of these materials ar e attributed to the high values of the van der Waals components and th e low prefactor mobilities. The degree of positional disorder is simil ar to literature values reported for a wide range of doped polymers.