PHOTOCURRENT AND OPTICAL LIMITING STUDIES OF C-60 FILMS AND SOLUTIONS

Photocarrier generation efficiency (PGE) and reverse saturable absorpt ion (RSA) measurements have been conducted on fullerene (C-60)/polymet hyl methacrylate (PMMA) thin films and C-60/toluene solutions. The pho tocarrier generation has been measured at 330 and 532 nm for various c oncentrations and electron donor/acceptor addition. The photocarrier g eneration yield for 330 nm traversed a maximum with increasing concent ration which was not observed for 532 nm excitation. This concentratio n dependence is explained via electron-hole pair dissociation. A large enhancement of photocarrier generation was observed in the case of tr iphenylamine addition to C-60. Fullerene solutions containing electron donors and accepters demonstrated optical limiting with a vertical sh ift in the transmittance versus fluence optical limiting plots. This v ertical shift could not account for the optical limiting profile of C- 60/dimethylbenzoquinone samples.