Charge trapping in molecularly doped polymers

Hole mobilities have been measured in di-p-tolylphenylamine doped poly(styrene) containing p-diethylaminobenzaldehyde diphenylhydrazone (DEH), an 0.32 eV trap. A DEH molar concentration of 10(-5) decreases the mobility by a factor of two. For concentrations in excess of 10(-5), the mobilities decrease with increasing concentration as approximately sigma(-1.1), the field and temperature dependencies remaining essentially unchanged. For concentrations in excess of 10(-1), transport is dominated by trap-to-trap hopping and the mobility increases with increasing rnp concentration. The results are discussed within the framework of the Hoesterey-Letson formalism and the recent simulations of Wolf et al. and Borsenberger et al.