HOLE TRAPPING IN MOLECULARLY DOPED POLYMERS : THE HOESTEREY-LETSON FORMALISM

Hole trapping has been investigated in di-p-anisyl-p-tolylamine (DAT), tri-p-tolylamine (TTA), di-p-tolylphenylamine (DTP), and diphenyl-p-tolylamine (DPT) doped poly(styrene) containing different concentrations of tri-p-anislyamine (TAA). From oxidation potential measurements, TAA is a trap for DAT, TTA, DTP, and DPT with depths 0.07, 0.22, 0.27, and 0.34 eV, respectively. In such a way, it is possible to investigate the effect of trap depth using the same trap molecule. The mobilities decrease with increasing trap depth and concentration. For a TAA molar concentration of 10-2, the room temperature mobilities are suppressed by as much as four orders of magnitude. The results are compared to predictions of the Hoesterey-Letson formalism and discussed within the framework of the recent simulations of Wolf et al.. [Chem. Phys. 222 (1997) 259] and Borsenberger et al.. (submitted to Chem. Phys.)