<title>Hole transport in N,N-bis(2,2-diphenylvinyl)-N,N'-diphenylbenzidine- doped poly(styrene)</title>

Abstract

Hole mobilities have been measured in poly(styrene) (PS) doped with N,N-bis(2,2-diphenylvinyl)-N,N'-diphenylbenzidine (ENA). ENA is a weakly polar donor molecule with a dipole moment of 0.86 Debye. The mobilities were unexpectedly high, exceeding 10-3 cm2/Vs at high fields. The results are described within the framework of a formalism based on disorder, due to Bassler and coworkers. The formalism is based on the argument that charge transport occurs by hopping through a manifold of localized states that are distributed in energy. The key parameters of the formalism are the energy width of the hoping site manifold, the degree of positional disorder, and the prefactor mobility. For ENA doped PS, the widths are between 0.079 and 0.090 eV, increasing with increasing dilution. The widths are described by an argument based on dipolar disorder. The argument is based on the assumption that the total width is comprised of a dipolar component and a van der Waals component. Due to the very low dipole moment of ENA, the dipolar component is near-zero and the total width determined by the van der Waals component. The degree of positional disorder is between 1.6 and 4.8, increasing with increasing dilution. The prefactor mobilities are between 4.2 multiplied by 10-5 and 1.9 multiplied by 10-2 cm2/Vs, and can be described by a wavefunction decay constant (rho) 0 of 1.0 angstrom.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.