ELECTRONIC CARRIER TRANSPORT AND PHOTOGENERATION IN BUCKMINSTERFULLERENE FILMS

Information concerning electronic carrier transport and photogeneration in films of undoped C60/70 has been obtained from photoinduced xerographic discharge curves in sublimed films up to 40 mum in thickness. The results, using strongly absorbed light, unambiguously reveal that the electron range, mutau, where mu is the electron drift mobility and tau the deep trapping lifetime, is approximately 10(-7) cm2/V. By contrast, a barely detectable discharge is observed to be associated with holes. The photogeneration efficiency for electrons is field dependent with a value at 4000 angstrom of 5 X 10(-2) at a field of 2 X 10(5) V/cm. These results are discussed in a context where both charge photogeneration and transport in undoped C60/70 involve localized electronic states.