Imaging member having a dual charge transport layer

An imaging member comprising

• an electrically conductive supporting substrate or a supporting substrate comprising an electrically conductive layer;
• an optional hole blocking layer;
• a charge generating layer;
• and
• a charge transport layer having at least a first (bottom) charge transport layer and a second (top) charge transport layer each of which comprises a hole mobility organic transport compound molecularly dispersed in a film forming polymer binder;
• wherein the first (bottom) charge transport layer comprises a hole mobility organic transport compound selected from the group consisting of triphenylmethane;
• bis(4-diethylamine-2-methylphenyl)phenylmethane;
• 4,4′-bis(diethylamino)-2,2′-dimethyltriphenyl-methane;
• N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine;
• N,N′-diphenyl-N,N′-bis(4-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine;
• N,N′-diphenyl-N,N′-bis(alkylphenyl)-1,1′-biphenyl-4,4′-diamine;
• N,N′-diphenyl-N,N′-bis(chlorophenyl)-1,1′-biphenyl-4,4′-diamine;
• tritolylamine;
• N,N′-bis-(3,4-dimethylphenyl)-4-biphenyl amine;
• N,N′-bis-(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-1,1′-(3,3′-dimethylbiphenyl)-4,4′-diamine;
• N,N′-diphenyl-N,N′-bis(halophenyl)-1,1′-biphenyl-4,4′-diamine;
• N,N′-diphenyl-N,N′-bis(hydroxyphenyl)-1,1′-biphenyl-4,4′-diamine;
• phenanthrene diamine;
• arylamine;
• enamine;
• stilbene;
• and hydrazone molecules;
• and
• wherein the first (bottom) charge transport layer comprises between about 50 and about 90 weight percent hole mobility organic transport compound based on the total weight of the first (bottom) charge transport layer;
• wherein the second (top) charge transport layer comprises a film forming polymer binder and a high hole mobility organic transport compound selected from the group consisting of a diamine represented by the formula:
• where R1, R2, R3, R4, R5, and R6 are independently selected from the group consisting of hydrogen, halogen, alkyl, aryl, and a cyclo-alkyl group having 1 to 18 carbon atoms, and at least one of R1, R2, R3, R4, R5, and R6 is halogen;
• wherein the second (top) charge transport layer comprises a lesser amount by weight of this high hole mobility diamine organic transport compound than the hole transport compound used in the first (bottom) charge transport layer;
• and wherein the film forming polymer binder is selected from the group consisting of polycarbonates, polystyrene, and poly(vinyl carbazole).