THICKNESS EFFECT ON PHOTOCONDUCTION SPECTRA IN SOLID FILMS OF C-60

Steady-state photoconductivity action spectra in the wavelength range between 200 and 800 nm have been measured in C-60 formed vacuum evapor ated films of different thickness. The photoconduction can be describe d by the interplay between two charge generation mechanisms : auto-ion ization of excited states in the bulk, accompained by excitonic inject ion of electrons from the Al cathode. The thickness of the films reduc es the negative-to-positive photocurrent ratio in the strongest absorp tion region.