CONDENSED MATTER: Dielectric and Optical Properties (PACS 77-79)-Changes in the photoelectrical properties and generation of photoinduced defects under lig... Academic Article uri icon

abstract

  • We report on the time development of surface photovoltage (SPV) and electron paramagnetic resonance (EPR) spectra for C 60 films irradiated by room light in air. Such exposure is shown to result in the progressive reduction of the SPV signal at 0.9–1.1 eV and in an increase in the signal at approximately 1.3 eV, as well as in the reduction of the signals at about 1.6 and 2.3 eV. A decrease in the dark contact potential difference signal as a result of surface band-bending reduction is also observed after exposure. These results are explained assuming that gap states at E c−(0.9–1.1) eV in our samples are attributed to nonbonded intercalated O 2 in the C 60 lattice while other states at E v+ 1.3 eV are related to oxygen chemically bonded to the C 60 molecules. EPR measurements reveal that light/air exposure causes an increase in the number of C 60+ paramagnetic defects. A hypothesis …

publication date

  • January 1, 1998