Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1999-01-06
2001-09-04
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S504000, C313S503000, C345S082000
Reexamination Certificate
active
06285124
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an organic EL (Electroluminescence) display panel and its manufacturing method, and particularly to an organic EL display panel and its manufacturing method using a conductive high polymer layer between an anode layer and an organic EL layer.
BACKGROUND OF THE INVENTION
A display panel has been known which uses an organic electroluminescence element (hereinafter referred to as “organic EL element) which passes a current through a fluorescent body formed on a glass plate or a transparent organic film to emit light. The organic EL element, as shown in
FIG. 4
, includes an organic layer
2
comprising a plurality of transparent electrodes of ITO, a conductive high polymer layer
104
for improving reliability, an organic EL layer
3
comprising a hole transporting layer and a light emitting layer, and a cathode layer
1
comprising a plurality of metallic electrodes intersecting the anode layer
2
. These layers are successively stacked on a transparent substrate
6
of glass or the like. The anode layer
2
and cathode layer
1
, between which the organic EL layer
3
intervenes and which are opposite to each other to form a couple, constitutes a light emitting portion serving as an organic EL layer
3
. An intersecting region where each of the transparent electrodes of the anode layer
2
and each of the metallic electrodes of the cathode layer
1
are opposite to intersect constitutes a pixel of one unit.
As the cathode
1
, a metal having a small work function such as an alloy of Al, In, Ag, etc. (e.g. Al-Li alloy) is used. As the anode layer
2
, a conductive material having a large work function of ITO (work function of ITO=about 0.5 eV) or gold (work function of Au=about 5.1 eV) is used. When gold is used as an electrode material, the electrode is made semi-transparent.
As the high polymer layer
104
, polyaniline is used. Improvement of reliability in the conductive high polymer layer is disclosed in JP-A-9-45479. (The term “JP-A” as herein means “unexamined published Japanese patent application”.)
When the technique for improving reliability by the conductive high polymer layer is adopted for a display panel having a structure where an anode and cathode are divided into plural regions, such as a dot matrix, because the resistance of the conductive high polymer layer is low, the adjacent anode regions are electrically connected to each other and hence crosstalk occurs. Namely, even when a current is not passed through the anode in order that the pixel on a certain anode does not emit light, the current flows from the adjacent anode because the electric resistance of the high polymer layer is low. Thus, the pixel which should not emit light will emit light. As a result, a desired image cannot be obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an organic EL display panel with improved reliability and a method of manufacturing it in such a manner that after a high polymer layer has been deposited on an anode layer, a desired region is made conductive or non-conductive to form the conductive high polymer layer thereon.
In order to solve the above problem, an organic EL display panel defined in a first aspect of the present invention comprises a plurality of anode layers laminated on a substrate and arranged with intervals in a direction perpendicular to the laminating direction (hereinafter sometimes simply referred to as a plurality of anode layers at intervals), a high polymer layer made of polymeric material, an organic EL layer and a plurality of cathode layers arranged with spaces (intervals) in a direction perpendicular to the laminating direction, these layers being successively stacked, and characterized in that gap regions corresponding to the intervals in the high polymer layer (gap regions disposed between the adjacent anode layers) are formed to have a lower conductivity than regions corresponding to the anode layers (energizing regions facing the cathode layers).
The organic EL display panel defined in a second aspect of the present invention is an organic EL display panel according to the first aspect of the present invention, wherein the gap regions of the high polymer layer are insulating (insulative)
The organic EL display panel defined in a third aspect of the present invention is an organic EL display panel comprising a plurality of anode layers formed to be arranged at predetermined intervals on a substrate, and a conductive high polymer layer, an organic EL layer and a cathode layer, these layers being successively stacked on the anode layers, wherein the conductive high polymer layer, after it has been stacked, is subjected to a conductivity reducing step of reducing the conductivity of gap regions corresponding to the intervals.
The organic EL display panel defined in a fourth aspect of the present invention is an organic EL display panel according to the third aspect of the present invention, wherein the gap regions of the conductive high polymer layer is made insulating by the conductivity reducing step.
The organic EL display panel defined in a fifth aspect of the present invention is an organic EL display panel according to the third or fourth aspect of the present invention, wherein the conductive high polymer is made of polyaniline mixed with camphor-sulfonic acid, and the conductivity reducing step is carried out in such a manner that the gap regions of the conductive high polymer layer is immersed in an alkaline solution.
The organic EL display panel defined in a sixth aspect of the present invention is an organic EL display panel comprising a plurality of anode layers formed to be arranged at intervals on a substrate, a non-conductive high polymer layer, which can be imparted conductivity, formed thereon, and an organic EL layer and a cathode layer which are successively stacked on the non-conductive high polymer layer, wherein the non- conductive high polymer layer, after it has been stacked, is subjected to a conductivity imparting step of reducing the conductivity of energizing regions corresponding to the anode layers.
The organic EL display panel defined in a seventh aspect of the present invention is an organic EL display panel according to the sixth aspect of the present invention, wherein the non-conductive high polymer is made of polyaniline, and the conductivity imparting step is carried out in such a manner that the energizing regions are immersed in an acidic solution.
The method defined in a eighth aspect of the present invention is a method of manufacturing an organic EL display panel comprising the steps of: forming a plurality of a plurality of anode layers so as to be arranged at predetermined intervals on a substrate; stacking a conductive high polymer layer on the substrate so as to cover the plurality of anode layers; reducing the conductivity of gap regions corresponding to the intervals of the conductive high polymer layer; and successively stacking an organic EL layer and a cathode layer on the conductive high polymer layer.
The method defined in ninth aspect of the present invention is a method of manufacturing an organic EL display panel according to the eight aspect of the present invention, wherein the step of reducing conductivity is to make the gap regions insulating.
The method defined in a tenth aspect of the present invention is a method of manufacturing an organic EL display panel according to the eighth or ninth aspect of the present invention, wherein the conductive high polymer layer is polyaniline mixed with camphor-sulfonic acid, and the conductivity reducing step is carried out in such a manner that the gap regions of the conductive high polymer layer is immersed in an alkaline solution.
The method defined in a eleventh aspect of the present invention is a method of manufacturing an organic EL display panel comprising the steps of: forming a plurality of anode layers so as to be arranged at intervals on a substrate, stacking a non-conductive high polymer layer, which can be imparted conductivity, on
Nagayama Kenichi
Nakada Hitoshi
Ogasawara Atsushi
Patel Nimeshkumar D.
Pioneer Electronic Corporation
Santiago Mariceli
Sughrue Mion Zinn Macpeak & Seas, PLLC
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