DIPOLE-MOMENTS OF HOLE-TRANSPORTING MATERIALS AND THEIR INFLUENCE ON HOLE MOBILITY IN MOLECULARLY DOPED POLYMERS

Dipole moments have been measured for a number of hole-transporting do nor compounds. Where possible, the results are interpreted in terms of group dipole moments and molecular conformations. The mobility of hol es in molecularly doped polymers containing some of these compounds ge nerally (but not universally) correlates with the dipole moment of the donor, consistent with previous results. Compensating effects that ap parently contribute to the correlation are pointed out, as are difficu lties in constructing an ''equitable'' comparison of disparate materia ls. The physical origin of the correlation is discussed. An appendix p resents formulas for the distribution of possible hole energies for a donor molecule containing a dipolar substituent with a rotational degr ee of freedom.