DARK AND PHOTOCONDUCTIVITY BEHAVIOR OF C-60 THIN-FILMS SANDWICHED WITH METAL-ELECTRODES

Sandwich cells of C60 thin film with a front Al electrode reveal considerable rectifying effects and large photocurrents (quantum yields less-than-or-equal-to 54%) under air. The action spectra closely follow the optical absorption spectrum of the film. The relationship between photocurrent (J(ph)) and incident light intensity (P(in)) changes from J(ph) is-proportional-to (P(in))0.95+/-0.05 at P(in) < 3 X 10(-7) W/cm2 to J(Ph) is-proportional-to (P(in))0.53+/-O.03 at higher P(in), suggesting that the photocurrent is controlled by the interaction of excitons with impurity sites at surface and near-surface of C60 in the absence and presence of bimolecular recombination depending on light intensity.