Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2001-10-16
2003-09-23
Dinkins, Anthony (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S025000, C313S512000, C427S066000, C427S557000
Reexamination Certificate
active
06623324
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing an organic EL (electroluminescence) device and more particularly to the method for manufacturing the organic EL device that can prevent an occurrence of a leakage current caused by heat in an encapsulation process.
The present application claims priority of Japanese Patent Application No.2000-316419 filed on Oct. 17, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
As one type of EL devices to be used in a display device for information devices or a like, an organic EL device is developed.
FIG. 10
is a schematic diagram showing configurations of a conventional organic EL device. The conventional organic EL device, as shown in
FIG. 10
, includes a transparent insulating substrate
51
made of a glass substrate or a like, an anode
52
(lower electrode) formed on the transparent insulating substrate
51
and made of transparent conductive materials such as ITO (Indium Tin Oxide), a hole transporting layer
53
formed on the anode
52
, an organic light emitting layer
54
formed on the hole transporting layer
53
, a cathode
55
(upper electrode) formed on the organic light emitting layer
54
and made of MgAg (magnesium silver) and a cap
57
made of glass or a like and mounted via a resin for encapsulation
56
_on the transparent insulating substrate
51
on which main components including the anode
52
, hole transporting layer
53
, organic light emitting layer
54
, and cathode
55
are formed, in a manner so as to cover the main components.
As the above resin for encapsulation
56
, for example, a UV (Ultra-Violet ray curable resin is used and by irradiating the resin for encapsulation
56
with light containing UV fed from a light source, the resin for encapsulation
56
is cured and is used for encapsulation. At this point, in addition to the UV, heat is emitted from the light source and the emitted heat is further added to the main components of the EL device and, as a result, its temperature reaches 50° C. to 60° C. on the transparent insulating substrate
51
. Moreover, since it is impossible to completely cure the resin for encapsulation
56
only by applying the UV to the resin for encapsulation
56
, after the irradiation with the UV, heat with a temperature of 40° C. to 60° C. is added for about a half day to perform after-curing processing.
However, due to heat existing on the transparent insulating substrate
51
in the encapsulation process and heat produced by the after-curing process, a defect occurring on an interface of the organic light emitting layer
54
and the cathode
55
in an unstable state is increased. The occurrence of the defect means that an impurity level caused by a lattice defect or a like is formed in a region where an interface level is to be formed. The existence of the defect causes a path other than that through which a carrier flows originally to be produced and occurrence of the leakage current to be increased. Moreover, there is a danger that the cathode
55
is shorted to the anode
52
. As a result, a characteristic of the organic EL device becomes unstable, causing an increase of defects. Moreover, since the UV light causes the increase in defects existing on the interface, when the UV light is applied, considerations are given to avoid application of the UV light to the main components of the organic EL device. Therefore, to stabilize characteristics of the organic EL device by preventing the occurrence of the leakage current caused by heat in the encapsulation process, it is desirous to remove the defects before being encapsulated.
In the manufacturing of each of various electronic components, in order to achieve stable characteristics of the organic EL device, generally, aging processing is performed. For example, a semiconductor aging apparatus used in a test for an EPROM (Electrically Programmable Read Only Memory) is disclosed in Japanese Laid-open Patent Application No. Hei 1-191075. The semiconductor aging apparatus, as shown in
FIG. 11
, is so constructed that the aging is performed by applying light with wavelengths of more than 400 nm from a mercury lamp
63
attached outside a thermostatic storage oven
61
through an optical filter
64
to an EPROM substrate
62
mounted in the thermostatic storage oven
61
maintained at temperatures of 200° C. to 300° C. This causes an electron existing in a floating gate to be excited and the excited electron to be discharged beyond a barrier, thus improving a storage characteristic of the organic EL device.
A method of aging of an EL display adapted to stabilize light emission luminance of an EL display panel is disclosed in, for example, Japanese Laid-open Patent Application No. Hei 4-79193.
In the disclosed aging method of the EL display panel, as shown in
FIG. 12
, when the aging is performed, since the organic EL device has many cells (each of them has both the_electrodes
72
and
73
), all the electrodes
72
and
73
are commonly connected, that is, one electrode
72
(for example, cathode) and the other electrode
73
(for example, anode) are commonly connected to the EL display panel
71
and a display voltage
74
fed from an alternating power source is applied between both the electrodes
72
and
73
to emit light and, at a same time, light having energy of more than 0.3 kW is applied to only a side of the EL display panel
71
from an aging light source
75
using a mercury lamp or a like. Thus, by combining irradiation of light and application of voltages, the aging is accelerated and time required for the aging is shortened.
However, the conventional aging processing disclosed above, since it is not intended to be used for aging of the organic EL device, has the following problems.
First, since the semiconductor aging processing disclosed in Japanese Laid-open Patent Application Hei 1-191075 is intended to be used for the EPROM being one of types of the semiconductor devices, it naturally uses the thermostatic storage oven
61
with its temperatures being maintained at 200° C. to 300° C. However, since the organic EL device has the organic light emitting layer
54
and is vulnerable to heat, it is not proper to use the above aging method for the organic EL device. That is, though, in the case of the organic EL device, the aging has to be preferably performed at ordinary temperatures, if the aging processing disclosed above is employed, as a result, the aging is performed at high temperature, which causes problems associated with heat, as described above. Moreover, since the aging processing disclosed above is intended to be applied to a test of the EPROM for screening, no consideration has been given to improvement of device characteristics by, for example, preventing the occurrence of the leakage current caused by heat in the encapsulation process, which presents a problem.
Next, in the aging processing disclosed in Japanese Laid-open Patent Application No. Hei 4-79193, display voltage fed from the alternating power source is applied between both the electrodes and, at the same time, the light using the mercury lamp is applied to the EL display panel. However, since the light energy used for the irradiation is as large as more than 0.3 kW, if it is employed in the aging for the organic EL device, the organic light emitting layer
54
degrades. Moreover, the application of the voltage is essential in the disclosed aging processing, however, since, in the manufacturing method of the organic EL device, almost all the processes have to be performed in an atmosphere of inert gas in order to prevent the degradation of the organic light emitting layer
54
, the application of the voltage is impossible. In the aging processing disclosed in Japanese Laid-open Patent Application No. Hei 4-79193, since the aging is performed in order to achieve stabilization of light emission luminance, no consideration has been given to the improvement of device characteristics by, for example, preventing the occurrence of the leakage curr
Dinkins Anthony
Estrada Angel R.
Hayes & Soloway P.C.
NEC Corporation
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