Improvement in Photoconductive Properties of Coumarin 30-Evaporated Film by Fullerene Doping for Blue-Sensitive Photoconductors

• Published in: Japanese Journal of Applied Physics 2010-11, Vol.49 (11), p.111601-111601-4
• Main Authors: Seo, Hokuto, Aihara, Satoshi, Kubota, Misao, Egami, Norifumi
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.49.111601

We fabricated two types of organic photoconductive film consisting of coumarin 30/tris(8-hydroxyquinoline)aluminum (Alq 3 ) and fullerene (C 60 , 10%) : coumarin 30 (90%)/Alq 3 by vacuum evaporation and measured the effect of doping C 60 as an electron acceptor on the photoconductive properties of the film. The spectral photoresponse characteristics of both films showed good wavelength selectivity in the blue-light region: the peak wavelength of a coumarin 30 neat film was 410 nm and that of a $\text{C$_{60}$}:\text{coumarin 30}$ codeposited film was 440 nm. The external quantum efficiency of the codeposited film reached 64% at an applied voltage of 10 V, while that of the neat film remained at 10% at its highest. These results clearly indicate that the dissociation of electron-hole pairs at the coumarin 30/C 60 interface occurs in the codeposited film.