The electrical conductivity in a zinc oxide thin film is increased by light absorption in an adjacent layer of eosin (Na). Activation spectra show that response is excited by irradiation in the eosin monomer and dimer absorption bands and in the long wavelength tail induced by the zinc oxide substrate. The photo-response in bilayers varies with the one-half power of the illuminance, builds up and decays by first-order processes, and is proportional to the zinc oxide dark current. The temperature dependence approximately follows the zinc oxide dark conductivity. Measurements with voltaic couples show that charge transfer takes place across the interface. Possible mechanisms are discussed.
S. J. DUDKOWSKI and L. I. GROSSWEINER, "Sensitization of Photoconduction in a Zinc Oxide Film by Eosin," J. Opt. Soc. Am. 54, 486-491 (1964)