Journal of Physical Chemistry vol:97 issue:34 pages:8808-8811
Hole mobilities have been measured in vapor deposited films of 5'-[4-[bis(4-ethylphenyl)amino]phenyl]-N,N,N',N'-tetrakis(4-ethylphenyl)-1,1':3',1''-terphenyl-4,4''-diamine(p-pEFTP), a compound containing three donor functionalities per molecule. The results are described within the framework of a model based on disorder, due to Bassler and co-workers. The model is based on the assumption that charge transport occurs by hopping through a Gaussian distribution of localized states with superimposed positional disorder. The key parameters of the model are sigma, the energy width of the hopping site manifold, and SIGMA, a parameter that describes the degree of positional disorder. For p-pEFTP, sigma = 0.068 eV and SIGMA congruent-to 1.0. A comparison of these results with literature results for compounds with similar donor functionalities leads to the conclusion that the energy width of the hopping site manifold is independent of the conjugation of the donor functionalities and largely determined by dipole moments associated with the donor molecules.