抄録
In a layered photoreceptor with metal-free phthalocyanine (H2·Pc) as the carrier generation layer (CGL), addition of electron acceptors to CGL was found to improve electrophotographic properties. The effect was clearly exhibited when aceptors whose electron affinities were between L1-L4eV were added to a H2·Pc/acceptor dispersion-coated CGL in a concentration of about 10 weight percent. The charge acceptance did not affected, but the photo-carrier generation efficiency increassed as a result of the interaction probably between excited H2·Pc and acceptor molecules and it raised the photosensitivity as much as 50%. Acceptors of affinity more than L5eV, however, increased the conductivity of CGL and consequently reduced the charge acceptance to an impractical level.
In order to assure a closer interaction between H2·Pc and acceptor molecules, co-sublimated CGL films of H2 Pc and 2,4,5,7-tetranitro-fluorenone (TeNF) were prepared in a vacuum chamber by the flash evaporation technique. The photosensitivity was further improved. The optimum concentration of TeNF in CGL was between 1 to 10 mol.%. The electrophotographic property was excellent. The initial surface voltage of 1000V was decayed to 500V by an exposure of 1.2 μJ/ cm2. It was found that the addition of TeNF to CGL improved not only the initial discharge rate but also the electric field dependence of the decay process.
