Changes in electronic and photoelectronic properties of fullerene (C60) and metal-free phthalocyanine (H2Pc) coevaporated thin films were investigated by changing their mixing ratio. The influences of thermal annealing and oxygen adsorption on the properties were also investigated. The electronic and photoelectronic properties changed by incororation of H2Pc into C60, and thermal annealing changed their properties dramatically. Thin films in which one component was doped lightly into the other showed high photoconductive sensitivity in comparison with that of C60 or H2Pc alone in over all visible region. Existence of sensitization center and process caused from minority carrier trapping was confirmed from thermal quenching of photoconductivity. Mechanisms for carrier generation and transport were discussed using a model in which photons of high and low energies were absorbed in C60 and H2Pc molecules, respectively, followed with majority carrier injection and trapping.
Ryoichi Yasuda, Manabu Takeuchi, "Photoconductivity of C60-H2Pc Coevaporated Thin Films" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP15), 1999, pp 691 - 694, https://doi.org/10.2352/ISSN.2169-4451.1999.15.1.art00081_2