decomp one part of a polyvinyl butyral resin 34 blx 34 produced by sekisui chemical co ltd was dissolved in 40 parts of cyclohexanone and the solution was mixed with 3 parts of the bisazo compound of formula i 1 the resulting mixture was throughly dispersed in a paint shaker and the dispersion was coated on an aluminum sheet using an applicator and dried to form a charge generating layer having a dry thickness of 0 2 u03bcm a uniform solution consisting of 1 part of n n 39 diphenyl n n 39 bis 3 methylphenyl 1 1 39 biphenyl 4 4 39 diamine 1 part of a polycarbonate resin 34 lexan 145 34 produced by general electric co molecular weight from 35 000 to 40 000 and 15 parts of dichloromethane was then coated on the charge generating layer by means of an applicator and dried to form a charge transport layer having a dry thickness of 20 u03bcm the thus produced electrophotographic photoreceptor was evaluated for performance characteristics by means of an electrostatic copying paper testing apparatus 34 sp 428 34 manufactured by kawaguchi denki seisakusho as follows the photoreceptor was negatively charged to 6 kv by corona discharge and allowed to stand in a dark place for 2 seconds the surface potential vpo volt at this point was measured thereafter the photoreceptor was exposed to light of a tungsten lamp at an illuminance of.