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 0.9ā€“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 cāˆ’(0.9ā€“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 ā€¦

publication date

  • January 1, 1998