Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
2000-02-10
2002-07-02
O'Shea, Sandra (Department: 2875)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S505000, C313S509000, C428S917000
Reexamination Certificate
active
06414432
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an organic electroluminescent (hereinafter referred to as “EL”) device and a method for manufacturing the same, and more particularly to an organic EL device constructed of a thin film of an organic compound material emitting light due to injection of positive holes and electrons and recombination therebetween while utilizing electroluminescence of the organic compound material, and a method for manufacturing the same.
An organic EL device is constructed into a laminate structure in which a thin film containing a fluorescent organic compound is interposed between anodes and cathodes. In the organic EL device thus constructed, positive holes and electrons are injected into the thin film, to thereby be recombined together, leading to production of excitons, resulting in display being carried out utilizing light (fluorescence, phosphorescence or the like) emitted from the excitons during deactivation thereof.
Now, a conventional organic EL device will be described with reference to FIG.
6
.
An organic EL device designated at reference numeral
101
includes a glass substrate
102
made of an insulating and transparent material, on which anodes
103
in the form of a transparent conductive film made of indium tin oxide (ITO) are arranged in a predetermined pattern such as, for example, a stripe-like pattern. The organic EL device also includes an organic EL layer
105
formed of a thin film made of an organic compound and arranged on the anodes
103
. The organic EL layer
105
includes a luminous layer. The organic EL layer
105
is formed thereon with cathodes
106
, which are made of a thin film of metal such as Al—Li or the like and arranged on the organic EL layer
105
in a predetermined pattern. The cathodes
106
may be arranged in, for example, a stripe-like pattern which cooperates with the stripe-like pattern of the anodes
103
to define a matrix.
In the organic EL device thus constructed, the cathodes
106
are typically formed by PVD such as molecular beam deposition, resistance heating or the like. In the conventional organic EL device shown in
FIG. 6
, the organic EL layer
105
is covered on a portion thereof on which the cathodes
106
are not to be arranged with masks
112
during formation of the cathodes
106
, so that deposition of the cathodes
106
is carried out from above the masks
112
. This permits the cathodes
106
to be formed on a portion of the organic EL layer
105
which are not covered with the masks
112
, leading to patterning of the cathodes
106
.
Unfortunately, formation of the cathodes
106
using the masks
112
requires to increase both dimensional accuracy of the masks
112
and accuracy of positioning of the masks
112
necessary to positionally correspond the cathodes
106
to the anodes
103
. In particular, information of a fine pattern wherein the cathodes
106
are arranged in a complicated manner rather than the above-described stripe-like manner defining the matrix, it is required to further increase dimensional accuracy of the masks
112
.
Also, formation of the cathodes
106
by means of the masks
112
tends to cause a material for the cathodes
106
to enter or intrude into a portion of the organic EL layer
105
on which formation of the cathodes is not desired such as the portion of the organic EL layer
105
covered with the masks
112
and the like during formation of the cathodes
106
. This often leads to short-circuiting between the cathodes
106
which must be electrically separated from each other.
In order to solve the problem, it is proposed to arrange a rib
109
between each adjacent two of the cathodes
106
to separate the cathodes from each other for insulation therebetween, as shown in each of FIGS.
7
(
a
) to
7
(
c
).
In FIG.
7
(
a
), the anodes
103
are previously formed thereon with the ribs
109
and then the organic EL layer
105
is formed on the anodes
103
, followed by formation of the cathodes
106
. The cathodes
106
are deposited on the organic EL layer
105
while being separated from each other through the ribs
109
. Such formation of the cathodes
106
by means of the ribs
109
increases both dimensional accuracy and positioning accuracy of the cathodes as compared with those by means of the masks
112
.
However, in formation of the cathodes
106
using the ribs
109
shown in FIG.
7
(
a
), the cathodes which must be separated from each other on both sides of each of the ribs
109
fail to be separated from each other due to adhesion of the cathode material to the rib
109
. In order to solve the problem, ribs
109
shown in FIGS.
7
(
b
) and
7
(
c
) are proposed for formation of the cathodes
106
.
The rib
109
shown in FIG.
7
(
b
) is formed into a downwardly or invertedly tapered shape in section to prevent the cathode material from reaching a lower portion of the rib
109
. Alternatively, the rib
109
may be formed into a T-like shape in section rather than the invertedly tapered shape, resulting in a shade being formed under the rib
109
.
The rib
109
shown in FIG.
7
(
c
) is formed into an increased height, so that the cathode material may be obliquely deposited on the organic EL layer
105
from one side of the rib
109
. This permits the cathode,
106
to be satisfactorily blocked on the other side of the rib
109
.
In the rib
109
shown in FIG.
7
(
b
) proposed in order to improve the rib of FIG.
7
(
a
), although the invertedly tapered configuration of the rib
109
effectively prevents the cathode material from reaching the shade under the rib
109
, it fails to permit the organic EL layer
105
formed prior. to formation of the cathodes
109
to be formed on the shade of the rib
109
. Thus, when the cathode material intrudes into a portion of the anodes on which the organic EL layer
105
fails to be formed, short-circuiting occurs between the anodes
103
and the cathodes
106
. Thus, the rib
109
shown in FIG.
7
(
b
) requires to rotate the substrate
102
during formation of the organic EL layer
105
, to thereby permit an organic material for the organic EL layer
105
to be deposited under the rib
109
. Also, in the rib
109
of FIG.
7
(
b
), it is required to subject the rib
109
to etching to form it into the invertedly tapered shape after such arrangement of the rib
109
on the anode
103
as shown in FIG.
7
(
a
).
In the rib
109
shown in FIG.
7
(
c
), an increase in height of the ribs
109
and oblique deposition of the cathodes
106
on the organic EL layer
105
cooperate with each other to separate the cathodes
106
from each other. However, requirements on an aspect ratio (height/width) in section of the rib
109
renders an increase in height of the rib substantially difficult. Also, the oblique deposition causes a direction in which patterning of the ribs
109
is carried out to be limited to only a vertical direction or a manner in which the patterning is carried out to be limited to only a stripe-like manner, to thereby fail to provide complicated patterning of the ribs
109
which permits bending or meandering of the cathodes
106
.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide an organic EL device which is capable of permitting insulation between electrodes during patterning of the electrodes to be reliably and readily ensured.
It is another object of the present invention to provide a method for manufacturing an organic EL device which is capable of reliably and readily accomplishing insulation between electrodes during patterning of the electrodes.
In accordance with one aspect of the present invention, an organic EL device is provided. The organic EL device includes a substrate, on which first electrodes and second electrodes are arranged. The first electrodes and/or second electrodes are formed to be transparent. The organic EL device also includes an organic EL layer including a luminous layer and arranged on the first electrodes. The sec
Hieda Shigeru
Ogawa Yukio
Alavi Ali
Futaba Corporation
O'Shea Sandra
Oblon, Spivak, McClelland, Maier & Neustad, P.C.
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