Dispersive nature of hole transport in polyvinylcarbazole

Hole transport in polyvinylcarbazole (PVK) is investigated, with a particular emphasis on comparing the experimental results with the theoretical predictions of the continuous-time random walk (CTRW) model. It is found that hole transport in this system exhibits all of the characteristic features of the CTRW model including universality, the predicted functional form of the time-of-flight transient, and the appropriate thickness dependence of the transit time. The electrical field dependence of the transit time has also been investigated. It is not possible to distinguish which of the various field-dependence models describes hole transport in PVK. In particular, both the Poole-Frenkel and kinetic models of the hopping process fit the data with physically reasonable parameters. © 1989 The American Physical Society.