Photoleitfaehige Schicht

1375719 Photo-conductive material KALLE AG 1 Dec 1971 [3 Dec 1970] 55758/71 Heading G2C A photo-conductive material comprises one or more aromatic photo-conductors and an electron acceptor other than 2, 4, 7-trinitrofluorenone. The photo-conductor has an ionization potential between 5 and 8 eV and; the electron acceptor has an electron affinity between 0.5 and 1.5 eV and passes at least one cross-conjugated # - electron system and the electron acceptor is present in the ratio of 0.3 to 1.3 moles per mole of photo-conductor base unit. In the embodiments poly vinyl carbazole or N-vinyl carbazole and electron acceptor are mixed with a polyester and an organic solvent and coated on an evaporated film of aluminium on a polyester support. The electron acceptor is preferably a polynitrated derivative of naphthalene, azlactone, anthraquinone, cyclohexanone or acenephthene but other electron acceptors are specified. The Specification also discloses the use of tetrachlorophthalic anhydride, 1, 3, 6, 8-tetranitrocarbazole,2, 3-dichloronaphthoquinone, 2, 3-dicyanonaphthoquinone and 2-choloro-3-nitro-1,4-naphthoquinone to sensitize N-vinyl-carbazole but these are not as effective.