Hole mobilities have been measured in vapor deposited films of 1, I-bis ( di -4-toly laminopheny 1) cyclohexane (T APC) and T APC-doped bisphenol-A-polycarbonate (BPPC). Over an extended range of temperatures, the mobilities decrease with increasing field at low fields. At high fields, a log Jl a: E1!2 relationship is observed with a slope that approaches zero at high temperatures. The results are described within the framework of the disorder transport formalism. By comparison of the experimental results with Monte Carlo simulations, we show that the observed behavior is a signature of the simultaneous presence of diagonal and off-diagonal disorder. Agreement between simulation results and experiment is excellent. Generalizing these results provides a framework for determining the magnitude of the relevant diagonal and off-diagonal disorder parameters from an analysis of mobility measurements.

Charge transport in molecular doped polymers has important applications in xerography, as well as being a theoretical challenge. Its investigation by determination of transient photocurrents is reviewed, with experiments and pertinent theories, such as hopping in a Gaussian density of states and the small polaron model, being outlined. The temporal features of the photocurrents, the field and temperature dependence of the charge carrier mobilities, and the influence of molecular properties—and what can be inferred from these—are discussed.

The effect of permanent dipoles on the density-of-states (DOS) function of an array of hopping sites is examined by summing the contributions of individual dipoles to the total potential at a given site. For relative dipolar site concentrations ≳0.1, the DOS function is of Gaussian shape. At lower concentrations, it approaches a Lorentzian. Good agreement with literature data on the dipolar contribution to the DOS function for hole transport in molecularly doped polymers and molecular glasses differing with regard to dipole moment and concentration of dipolar moieties is found.