EFFECT OF POLYMER MATRICES ON HOPPING CHARGE TRANSPORT IN MOLECULARLY DOPED POLYMERS

We have studied the effect of polymer matrices on time-of-flight (TOF) photocurrent pulse shape and the drift mobility of holes in polymers doped with 2-(p-dipropylaminophenyl)-4-(p-dimethylaminophenyl)-5-(o-chlorophenyl)-1, 3-oxazole in order to understand the nature of hopping charge transport in molecularly doped polymers (MDPs). The TOF pulse shapes in oxazole-doped polymers are classed into two groups: near rectangular or dispersive shapes. The drift mobility of holes in MDPs exhibiting near-rectangular TOF shape is large compared with that exhibiting dispersive. Moreover, the drift mobility of holes depends on the dielectric constant and the glass transition temperature of polymers. These results show that the polarization and phonon mode of polymers play an important role in hopping charge transport in MDPs.