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New Charge Transport Agents for Photoconductors

IP.com Disclosure Number: IPCOM000120124D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Adley, JM: AUTHOR [+6]

Abstract

4-Diethylaminobenzaldehyde diphenylhydrazone (DEH) represents a class of organic molecules which may be used for hole transport in organic layered photoconductors. DEH is contained in the charge transport layer (CTL) whose typical formulation is 40% by weight of DEH in a polymeric binder, and whose thickness is Z20 mm. Unfortunately, when the photoconductor is exposed to 400-480 nm light, DEH undergoes a photochemical reaction to an indazole derivative (*). Associated with the photochemistry is an inability of the photoconductor to completely photodischarge, thereby rendering the organic photoconductor unsuitable for further electrophotographic applications and severely curtailing its useful lifetime.

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New Charge Transport Agents for Photoconductors

      4-Diethylaminobenzaldehyde diphenylhydrazone (DEH)
represents a class of organic molecules which may be used for hole
transport in organic layered photoconductors.  DEH is contained in
the charge transport layer (CTL) whose typical formulation is 40% by
weight of DEH in a polymeric binder, and whose thickness is Z20 mm.
Unfortunately, when the photoconductor is exposed to 400-480 nm
light, DEH undergoes a photochemical reaction to an indazole
derivative (*).  Associated with the photochemistry is an inability
of the photoconductor to completely photodischarge, thereby rendering
the organic photoconductor unsuitable for further electrophotographic
applications and severely curtailing its useful lifetime.

      Disclosed is a new class of hydrazones similar to the structure
in DEH but which are considerably more stable to <480 nm light.  The
general structures of these derivatives are shown in the figure
above.  By placing methyl substituents in the ortho position of the
hydrazone phenyl ring, which is Zperpendicular to the plane of the
molecule, the photocyclization reaction is significantly inhibited.
Thus, organic photoconductors were formulated from each of the
prepared derivatives and their electrical properties measured as a
function of exposure to 400-480 nm light.  It was observed that the
residual surface charges on the photoconductor after photodischarge,
as a function of exposure to light (<480 nm), was significantly
reduced.  The photochemical rate of the DEH derivatives was also much
slower than DEH itself.

      Synthesis
N-o-tolyl-N-phenylamine .  98 g of o-methylacetanilide (EK Chemical),
129 g of bromobenzene (Aldrich Chemical), 136 g dry potassium
carbonate, and 20 g cuprous chloride were refluxed in a 500 ml resin
flash for 24 hours, cooled, and extracted with toluene.  The extract
was filtered and evaporated.  The crude N-o-tolyl-N-phenylacetamide
was hydrolyzed in 500 ml EtOH and 100 g KOH; the EtOH was evaporated
and the residue collected and poured into water. The aqeous solution
was ether e...