ELECTRONIC HOPPING VELOCITIES THAT DECREASE AS THE ELECTRIC-FIELD STRENGTH INCREASES

Two molecularly doped polymer systems have been found in which the drift velocity of holes at high field strength (E) is a decreasing function of E: Molecules containing multiple electron-donor moieties dissolved at low concentration in an amorphous polymer. The most likely explanation involves geometric disorder and hopping sites that are most readily escaped by hopping against the field direction.