HOLE TRANSPORT IN 1,1-BIS((DI-4-TOLYLAMINO)PHENYL)CYCLOHEXANE (TAPC) DOPED POLY(STYRENE)S

Hole mobilities have been measured in TAPC doped into a series of poly(styrene)s with different dipole moments. The results are described within the framework of the disorder formalism, due to Bassler and co-workers. In the disorder formalism, charge transport occurs when charges hop through a Gaussian distribution of localized states with superimposed positional disorder. The key parameters of the formalism are sigma, the energy width of the hopping site manifold and SIGMA, a parameter that describes the degree of positional disorder. The results show that sigma increases with increasing dipole moment of the polymer while SIGMA is independent of the polymer. The dependence of sigma on dipole moment is attributed to random fluctuations in electrostatic potential due to dipole moments of the polymer. The absence of a dependence of SIGMA on the polymer is suggested to be due to the fact that positional disorder is determined by packing constraints which are mainly determined by the styrene group of the polymer repeat unit.