JP2002093577A - Aging method of organic el device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aging method of an organic EL device that the change of chromaticity after shipment can be prevented, in the organic EL device which has a luminescence layer of which the chromaticity changes by its elasping luminescence time. SOLUTION: When the amount of the chromaticity change until the chromaticity of a luminescence layer 30 turns into the chromaticity which the chromaticity change is saturated from its early chromaticity, is made as 100%, the time length in which the aging is carried out, is made as the time length until the chromaticity of the luminescence layer 30 turns into the chromaticity which changes to at least 50% of the amount of chromaticity change concerned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic EL (electroluminescence) element having a light emitting layer whose chromaticity changes with the elapse of light emitting time, and more particularly, to preventing a change in chromaticity of the light emitting layer. Aging method.

[0002]

2. Description of the Related Art An organic EL element is self-luminous, has excellent visibility, and can be driven at a low voltage of several volts to several tens of volts, so that it can be reduced in weight including a driving circuit. So, organic E
The L element can be expected to be used as a thin-film display, lighting equipment, backlight and the like.

Conventionally, as an aging method for passing a current through the light emitting layer of an organic EL device, as described in Japanese Patent Application Laid-Open No. Hei. A method has been proposed.

[0004]

However, the present inventors are not limited to organic EL devices having a single-color (single) light-emitting layer, but are capable of mixing colors by stacking different-color light-emitting layers or arranging them in a plane. When the obtained organic EL device was examined, it was found that the following problems occurred.

[0005] That is, the operation of the organic EL element is performed by applying a direct current to the light emitting layer to emit light. There is a problem that the chromaticity changes, resulting in a light emission color different from the initial chromaticity.

For example, an organic EL having a light emitting layer formed by laminating a blue light emitting layer and a red light emitting layer to obtain a mixed color of both light emitting layers
When the device emits light with the same current value during driving, the emission color is CIE (International Commission on Illumination) chromaticity coordinates, which initially was (0.33, 0.35).
After 100 hours (0.315, 0.335), 1000
After hours, it changed to (0.312, 0.325).

Further, when the change in the chromaticity of the mixed colors of the different color light emitting layers was examined by an emission spectrum, as shown in FIG. 10, the change in the luminance balance of each monochromatic spectrum (FIG. 1)
In addition to the change in the light emission position inside the light emitting layer, the change in the peak position of the light emission spectrum caused by optical interference (the solid line in FIG. It is also found that the change in chromaticity also occurs due to the change in the chromaticity.

[0008] Further, the occurrence of chromaticity change due to the change of the peak position of the emission spectrum is considered that the chromaticity change may occur not only in the mixed color type but also in an organic EL device having a single color light emitting layer.

From the above study, in order to manufacture an organic EL device in which chromaticity change after shipment is prevented, an aging method that focuses only on luminance deterioration as in the aging method described in the above-mentioned conventional publication is considered. Instead, it is necessary to create an aging method that focuses on chromaticity change.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and relates to an organic EL device having a light-emitting layer whose chromaticity changes with the lapse of light-emitting time. It is intended to provide an aging method.

[0011]

The present inventors have studied the change in the emission color with respect to the emission time. As a result, the change in the emission color greatly changes in the initial stage of operation, and changes relatively with the lapse of time. I found that it was getting smaller. Therefore, it was conceived that if a large chromaticity change was forcibly caused by aging before shipment, the chromaticity change after shipment could be reduced.

According to the first aspect of the present invention, there is provided an organic EL device having a light emitting layer whose chromaticity changes with the lapse of light emitting time, wherein the chromaticity of the light emitting layer is predetermined. It is characterized in that aging is performed in which a current is supplied to the light emitting layer so as to fall within a change within the range, and the luminescent layer is shipped after the aging.

According to the present invention, the chromaticity of the light emitting layer falls within a predetermined range by aging before shipment, so that the chromaticity can be prevented from changing after shipment. Therefore, according to the present invention, it is possible to provide an aging method for an organic EL device capable of preventing a change in chromaticity.

According to the study of the present inventors, when the chromaticity change from the initial chromaticity to the chromaticity at which the chromaticity change is saturated from the initial chromaticity is assumed to be 100%, The time after which the chromaticity of the light emitting layer changes rapidly becomes longer than the time until the chromaticity of the layer becomes the chromaticity changed by 50% of the chromaticity change amount. Therefore, it was found that there was no practical problem if the chromaticity of the light emitting layer was changed to 50% of the chromaticity change amount by aging.

The invention described in claim 2 has been made in view of the result of this study, and the time for performing aging is reduced.
Assuming that the chromaticity change from the initial chromaticity to the saturated chromaticity of the chromaticity change was 100%, the chromaticity of the luminescent layer changed at least 50% of the chromaticity change amount. It is characterized by the time until the chromaticity is reached. Thereby, the chromaticity can be prevented from changing after shipment, so that it is possible to provide an aging method for an organic EL device capable of preventing the chromaticity from changing.

According to the study of the present inventors, an organic E having a light emitting layer whose chromaticity changes with the lapse of light emitting time.
In the L element, depending on the material of the light emitting layer, the chromaticity change characteristic of the light emitting layer may have an inflection point, that is, an extreme value, from the initial chromaticity to the chromaticity at which the chromaticity change is saturated. I found it.

In the organic EL device having such an extreme value, the chromaticity of the light-emitting layer changes greatly from the initial chromaticity to the extreme chromaticity, and after the extreme chromaticity is reached. It changes greatly until the chromaticity of the light emitting layer becomes saturated chromaticity again. Therefore, when performing aging, it is necessary to distinguish between the time from the beginning to the extreme value and the time thereafter.

The invention according to claim 3 relates to an aging method for an organic EL element having such an extreme value, and the aging time is reduced by changing the chromaticity of the light emitting layer from the initial chromaticity. The time until the chromaticity of the light emitting layer is reached, and the chromaticity of the light emitting layer when the chromaticity change amount from the extreme chromaticity to the chromaticity in which the chromaticity change is saturated is assumed to be 100%. Is the total time until the chromaticity changes by at least 50% of the chromaticity change amount.

Accordingly, the light emitting device has a light emitting layer whose chromaticity changes with the elapse of the light emitting time, and the chromaticity change characteristic of this light emitting layer is changed from the initial chromaticity to the saturated chromaticity change. In an organic EL element having an extreme value, chromaticity can be prevented from changing after shipment. Therefore, it is possible to provide an aging method for an organic EL device capable of preventing a change in chromaticity.

Here, in the aging method according to any one of the first to third aspects, the light emitting layer is formed by laminating a plurality of layers that emit light of different colors, and the color mixing of the plurality of layers is not performed. What emits light (Laminated arrangement type of different color light emitting layer)
In addition, the light emitting layer has a structure in which a plurality of layers emitting different emission colors are arranged in the same plane, and a mixture of the plurality of layers emits light (a plane arrangement type of different color emission layer). Can also be applied.

Further, since the plurality of different color light emitting layers are different from each other in material, film thickness, etc., the optimum aging time is different. Here, in the planar arrangement type of the different color light emitting layers, it is possible to monitor the chromaticity during aging for each of the plurality of layers arranged in a plane.

Therefore, the aging time is obtained for each of the plurality of layers, and the aging is performed for the longest time among the obtained aging times (the invention of claim 6). Aging can be appropriately performed on all of the above layers, which is preferable.

According to the study of the present inventors, the change in chromaticity due to aging is promoted as the current flowing through the light emitting layer is increased by aging or as the temperature at the time of aging is increased.

Therefore, in order to shorten the aging time, the aging is performed with a current that is higher than the luminance used by the organic EL element (the invention of claim 7). It is preferable to carry out at a temperature higher than the operating temperature of the EL element (the invention of claim 8).

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention shown in the drawings will be described below. FIG. 1 is a diagram showing a schematic cross-sectional configuration of an organic EL device of a stacked arrangement type of different color light emitting layers according to the first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a substrate having transparency to visible light, which is made of, for example, glass. An anode 20 made of a transparent conductive film is formed on one surface of the substrate 10. The anode 20 can be made of, for example, indium-tin oxide (ITO) or indium-zinc oxide. The thickness of the anode 20 is about 100 nm to 1 μm, preferably 150 nm.
nm.

On the anode 20, a hole transporting layer 31 made of an organic material having a hole transporting property is laminated.
In this example, the hole transport layer 31 is made of α-naphthylphenylbenzene (α-NPD), and has a thickness of about 20 nm.

On the hole transporting layer 31, a hole transporting light emitting layer 32a is laminated. The hole-transporting light-emitting layer 32a is formed by using a hole-transporting organic material as a base material and adding a fluorescent dye. In this example, α-NP as the base material is used.
In D, 1 w of perylene as a fluorescent dye that emits blue light is used.
t%, and its film thickness is about 20 nm.

An electron transporting light emitting layer 32b is formed on the hole transporting light emitting layer 32a. The electron transporting light emitting layer 32b is formed by adding a fluorescent dye to an electron transporting organic material as a base material. In this example, BAlq (bis (-2-methyl-quinolinolate)-
DCM- (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) as a fluorescent dye that emits red light on (4-phenylphenolato) aluminum (3) 0.5 wt% is added, and its film thickness is about 40 nm.

Here, the hole transporting light emitting layer 32a is configured as a blue light emitting layer, the electron transporting light emitting layer 32b is configured as a red light emitting layer, and these different colored light emitting layers 32a and 32b are laminated. It is configured as a light emitting layer 32.

An electron transporting layer 33 made of an organic material having an electron transporting property is formed on the electron transporting light emitting layer 32b. In this example, the electron transport layer 33 is made of BAlq
And its film thickness is about 20 nm. Also,
In the present embodiment, these hole transport layer 31, light emitting layer 32,
The organic layer 30 is constituted by three layers of the electron transport layer 33.

The cathode 40 is formed on the electron transport layer 33. The thickness of the cathode 40 is 100 nm to 1 μm.
m, and the constituent material of the cathode 40 is LiF /
Al or other two-layer structure, or Mg and Ag, Al and Li
It is possible to use a mixed layer of such metal atoms. In this example, the cathode 40 is configured such that LiF is deposited to a thickness of 0.5 nm from the electron transport layer 33 side and Al is deposited to a thickness of 100 nm.

The organic EL device having such a structure is formed on the substrate 10 by using a known vapor deposition method, sputtering method or the like by using the anode 20, the hole transport layer 31, and the hole transport light emitting layer 32.
a, electron transporting light emitting layer 32b, electron transporting layer 33, cathode 4
It is formed by forming a film in the order of 0. Note that the hole transporting light emitting layer 32a and the electron transporting light emitting layer 32b in which the base material is doped with a fluorescent dye can be formed by co-evaporation of the base material and the fluorescent dye.

Then, the organic EL element thus formed is provided on the substrate 10 with each of the layers 20 to 40 as shown in FIG.
Is laminated with a can member 5 made of stainless steel or the like.
0 is used in a sealed state, and is driven at a constant current. Here, the can member 50 is adhered to the periphery of the substrate 10 with an adhesive 51, and the inside of the can member 50 is filled with dry nitrogen or the like.

In this organic EL device, a direct current (driving current) is applied between the pair of electrodes 20 and 40, so that the anode 20 passes through the hole transport layer 31 to the hole transporting light emitting layer 32 a. At the same time as holes are injected, electrons are injected from the cathode 40 into the electron transporting light emitting layer 32b via the electron transporting layer 33. Here, carriers (holes, electrons) move across the interface between the two light-emitting layers 32a and 32b and recombine to generate excitons.

Each of the fluorescent dyes in the two light emitting layers 32a and 32b transmits and receives the energy of the exciton, and simultaneously emits light of a color corresponding to the fluorescent peak wavelength of each solid state. It is visually recognized as light emission from. In this example, blue light emission is performed in the hole transporting light emitting layer 32a, red light emission is performed in the electron transporting light emitting layer 32b, and CIE chromaticity coordinates (0.33, 0.35) are used as color mixture.
White light emission with good color purity is obtained.

As described above, the light emitting layer 30 of the present embodiment is
When an electric field is applied, holes can be injected from the anode 20 or the hole transport layer 31, and electrons can be injected from the cathode 40 or the electron transport layer 33. It has a transport function of moving by electric field force, a light emitting function of providing a field for recombination of electrons and holes and connecting it to light emission, and the like.

In the present embodiment, since the organic EL element is used in the configuration as shown in FIG. 2, the luminescent layer 30 has such a configuration that the chromaticity of the luminescent layer 30 falls within a predetermined range. Aging is performed in which a current is passed through. Next, the aging method will be described.

The aging condition is determined in consideration of the light emission characteristics under driving conditions during use, that is, during operation. At this time, not only the luminance but also the change in chromaticity are measured. The measurement can be performed using a chromaticity meter that can measure luminance and chromaticity which are generally known.

For example, in the above-described organic EL device of the present example, when a direct current of 1 mA / cm ² is passed as a drive current, the initial luminance is 300 cd / m ² and the initial chromaticity of the light emitting layer 30 is CIE. The chromaticity coordinates (x, y) were (0.33, 0.35). When this drive current was kept constant and the chromaticity change was measured under a high-temperature operating environment of 70 ° C., the emission time was 100 hours (0.315, 0.3
35) and after 1000 hours (0.312, 0.32
Changed to 5).

FIG. 3 shows the chromaticity change in the organic EL element of this embodiment as a change in CIE chromaticity coordinates. FIG. 3 shows the coordinates x and y with respect to the light emission time (hr). FIG. 4 shows the change.

As shown in FIG. 4, the chromaticity (emission color) of the light emitting layer 30 changes greatly in the initial stage of the operation, changes relatively little with the elapse of the light emission time, and after 1000 hours. Saturates. Here, in FIG. 4, as the amount of chromaticity change, the change rate from 100 hours to 1000 hours is 0.0002 or less per 10 hours, and the chromaticity change is substantially 100 hours. It can be considered saturated.

By performing aging, the organic EL
It is possible to forcibly cause the above chromaticity change in the element. Therefore, in the present embodiment, aging is performed on the organic EL element while monitoring the chromaticity so that the chromaticity of the light emitting layer 30 falls within a change within a predetermined range.
We will ship after this aging.

According to this, since the chromaticity of the light-emitting layer is set to fall within a predetermined range by aging before shipping, it is possible to prevent the chromaticity from changing after shipping. For example, in the case of an organic EL element having chromaticity change characteristics as shown in FIG.
If the chromaticity change is forcibly caused to the chromaticity corresponding to 0 hours, the chromaticity change is substantially saturated, and the chromaticity change after aging is substantially prevented.

The chromaticity change amount (hereinafter referred to as an initial-saturated chromaticity change amount) from when the chromaticity of the light emitting layer 30 changes from the initial chromaticity to the chromaticity where the chromaticity change is saturated is set to 100%. .
For example, in FIG. 4, the initial chromaticity is (0.33, 0.3
5) The chromaticity after 1000 hours of saturation is (0.312,
0.325), and the initial-saturated chromaticity change amount (Δx, Δ
y) is (0.018, 0.025).

At this time, the time until the chromaticity of the light emitting layer 30 changes from the time until the chromaticity of the light emitting layer reaches the chromaticity changed by 50% of the initial-saturated chromaticity change amount. Has been experimentally found to increase rapidly. One example is
As shown in FIG.

FIG. 5 shows the emission time required for the chromaticity coordinate y to change by 10% of the initial-saturated chromaticity change amount in the organic EL device having the chromaticity change characteristics shown in FIG. It is shown. In FIG. 5, the horizontal axis represents the color change ratio (%), and the vertical axis represents the time required for each color change of 10% (h).
r) is shown.

For example, when the color change rate is 10% and the required time is 10 hours, and the color change rate is 100% and the required time is 250 hours, the chromaticity is the initial-saturated chromaticity change. The time required for changing the amount from 0% to 10% is 10 hours, and the time required for changing the chromaticity from 90% of the initial-saturated chromaticity change amount to 100% is 250 hours. Means that.

As can be seen from FIG. 5, after the chromaticity changes to 50% of the initial-saturated chromaticity change, 60%, 7%
The time of changing from 0%,..., 100% to the initial-saturated chromaticity change amount by 10% rapidly increases. That is, the chromaticity of the light emitting layer 30 is equal to the initial-saturated chromaticity change amount of 50.
Even if it changes in the range of% to 100%, the degree is such that the user (viewer) does not recognize a change in chromaticity (a degree that color unevenness is not recognized).

Therefore, if the chromaticity of the light emitting layer 30 is changed by at least 50% of the initial-saturated chromaticity change amount by aging, it can be said that there is no practical problem. From this,
By setting the aging time to a time until the chromaticity changes by at least 50% of the initial-saturated chromaticity change amount, the chromaticity change is saturated to such a degree that color unevenness is not recognized, and the chromaticity is changed after shipment. It can be prevented from changing.

As described above, the aging method of this embodiment is characterized in that aging is performed so that the chromaticity of the light emitting layer falls within a predetermined range. -At least 5 of saturation chromaticity change
By setting the time until the chromaticity changes by 0%, it is possible to prevent the chromaticity from changing after shipping.

Next, a specific example of the aging method of this embodiment and its effects will be described. In this example, in the organic EL element having the chromaticity change characteristics shown in FIG. 4, the initial-saturated chromaticity change amount (Δx, Δy) = (0.018, 0.
025) as 100%, a change of 83% on the x coordinate and 60% on the y coordinate for 100 hours (at 70 ° C. environment, driving current 1)
Aging was performed until a chromaticity equivalent to mA / cm ² ) was reached.

Here, in order to shorten the aging time, a driving current of 10 mA / cm ² was passed under an environment of 100 ° C., and aging was performed for 7 hours. At this time, the initial chromaticity (0.33, 0.35) changes to (0.315, 0.335) after the end of aging, and
Under the environment, the same chromaticity change as obtained by aging for 100 hours at a driving current of 1 mA / cm ² was obtained.

Then, in the organic EL device after the aging as described above, 1 mA was again obtained at 70 ° C.
/ Cm ² , the initial chromaticity was (0.315, 0.335), and the chromaticity after driving for 1000 hours was (0.312, 0.325). The color change was substantially prevented. As described above, according to the present embodiment, it is possible to provide an aging method for an organic EL element capable of preventing a change in chromaticity.

FIG. 6 is a graph showing the relationship between the luminance in aging and the aging time. Here, the horizontal axis indicates the luminance at the beginning of aging (initial luminance, cd / m ² ) as the luminance in aging, and this initial luminance can be changed by changing the current density of aging. The aging time (hr) on the vertical axis is the aging time required until the chromaticity becomes the same as the chromaticity (0.315, 0.335) after 100 hours in FIG. In FIG. 6, aging was performed in an environment at an ambient temperature of 70 ° C.

FIG. 7 is a graph showing the relationship between the ambient temperature (° C.) and the aging time (hr) in aging. Here, the aging time (hr) is a time required until the chromaticity changes by 50% of the initial-saturated chromaticity change amount in FIG. In FIG. 7, aging was performed by supplying a current so that the initial luminance was 300 cd / m ² .

As can be seen from FIGS. 6 and 7, as the luminance during aging increases, that is, as the current flowing through the light emitting layer 30 due to aging increases, or
The higher the temperature at the time of aging, the more the change in chromaticity due to aging can be promoted.

Therefore, in order to shorten the aging time, the aging is performed with a current having a luminance higher than the operating luminance of the organic EL element, or the aging is performed at a temperature higher than the operating temperature of the organic EL element. It is preferable to perform

Second Embodiment According to the study of the present inventors, in the organic EL device according to the first embodiment, the chromaticity change characteristic of the light emitting layer 30 is such that the chromaticity change is different from the initial chromaticity. In some cases, an inflection point, that is, an extreme value, was reached before the saturation chromaticity was reached. This phenomenon is shown in FIG. 8 as a change with respect to the light emission time (hr) for each of the coordinates x and y of the CIE chromaticity coordinates.

The second embodiment provides aging related to an organic EL device having such an extreme chromaticity change characteristic. Hereinafter, differences from the first embodiment will be described. The description of the part is omitted.

As shown in FIG. 8, the chromaticity decreases greatly from the initial chromaticity, decreases to an extreme value, rapidly increases again, and then gradually increases. Such a phenomenon is caused by the type and concentration of the organic material and the fluorescent dye of the light emitting layer 30,
It is considered that the chromaticity change characteristic has an extreme value due to the difference in the film thickness or the like.

In the organic EL element having such an extreme value, the chromaticity of the light emitting layer 30 changes greatly from the initial chromaticity to the extreme chromaticity, and after the extreme chromaticity is reached. Also greatly changes until the chromaticity of the light emitting layer becomes saturated chromaticity again. Therefore, when performing aging, it is necessary to distinguish between the time from the beginning to the extreme value and the time thereafter.

In the aging method of this embodiment,
As shown in FIG. 8, it is necessary to first perform aging for a time t1 (hereinafter referred to as “initial-extreme time”) until the chromaticity of the light emitting layer 30 changes from the initial chromaticity to the extreme chromaticity. Also,
Regarding the chromaticity change after the extreme value, the chromaticity change can be prevented based on the same idea as in the first embodiment.

That is, the chromaticity change amount (hereinafter, referred to as “the chromaticity after 1000 hours” in FIG. 8) from the extreme chromaticity of the chromaticity light emitting layer 30 to the saturated chromaticity (the chromaticity after 1000 hours in FIG. 8). (Extreme value-saturated chromaticity change amount) is set to 100%. Then, in addition to the initial-extreme time t1, the aging is performed for a time t2 until the chromaticity of the light emitting layer 30 becomes a chromaticity changed by at least 50% of the extreme-saturated chromaticity change amount. That is, the aging time is the total time (t1 + t2) of the two times.

As a result, in the organic EL device having the chromaticity change characteristic having an extreme value, the chromaticity of the light emitting layer is within a predetermined range (a range in which the user does not recognize the chromaticity change) by aging before shipping. Since the change can be accommodated, it is possible to prevent the chromaticity from changing after shipping. Therefore,
Also in this embodiment, an organic EL that can prevent chromaticity change
A method for aging the device can be provided.

(Third Embodiment) The third embodiment is different from the above-described first embodiment in which the different color light emitting layers are stacked and arranged, and the light emitting layer is composed of a plurality of layers emitting light of different colors. This is related to a planar arrangement type of a different color light emitting layer that emits a mixed color light of the plurality of layers. Hereinafter, differences from the first embodiment will be mainly described.

FIG. 9 is a diagram showing a schematic cross-sectional structure of an organic EL device of a planar arrangement type of a different color light emitting layer according to the present embodiment. 9, the substrate 10, the anode 20, the hole transport layer 31, the electron transport layer 33, and the cathode 40 are the same as those in FIG.

However, in FIG. 9, a plurality of anodes 20 (four shown in the figure) extending in the direction perpendicular to the paper are arranged in a stripe pattern.
Multiple extending in the direction perpendicular to the direction (only one is shown in the figure)
Are arranged in a stripe pattern, and the anode 2
A light emitting portion R is provided at a portion where 0 and the cathode 40 intersect and overlap with each other.
B is formed.

In FIG. 9, light emitting layers 35a and 35b having different emission colors are formed on adjacent anodes 20 with one anode 20 as a unit. In this example, the light-emitting layers 35a and 35b having different light-emitting colors are constituted by a blue light-emitting layer 35a and a red light-emitting layer 35b, and as shown in FIG.
The light-emitting portion indicated by the symbol R emits red light.

In this example, the blue light emitting layer 35a is made of B
An electron transporting light-emitting layer in which 1 wt% of perylene is added to Alq is employed, and DCM1 is added to Alq (tris (8-quinolyl) aluminum) with 0.5% as a red light-emitting layer 35b.
An electron transporting light emitting layer to which wt% is added is employed. The electron transport layer 33 is made of Alq. Also,
The thickness of the blue light emitting layer 35a is about 40 nm, and the thickness of the red light emitting layer 35b is about 30 nm.

The organic EL device of this embodiment is also used in a state sealed by a can member, as in FIG. Then, light is emitted by applying a direct current (drive current) between the pair of electrodes 20 and 40, and the light emitting layer 3
A mixed color of different emission colors from 5a and 35b is obtained. In this example, blue light emission from the blue light emitting layer 35a (light emitting portion B)
And CIE chromaticity coordinates (0.33, 0.35) as a color mixture by red light emission (light emitting portion R) from the red light emitting layer 35b.
White light emission with good color purity is obtained.

An aging method in the organic EL device of the present embodiment will be described. Here, in the present embodiment, similarly to the first embodiment, aging can be performed by focusing on the chromaticity of the mixed color from the organic EL element. An aging method specific to the planar arrangement type is also possible.

In this embodiment, the different color light emitting layers 35a, 35
Since b is arranged in a plane, luminance and chromaticity of each color can be measured instead of color mixture as in the case of the stacked arrangement type. Therefore, the chromaticity change characteristics of each color with respect to time can be obtained, and the chromaticity of the light emitting layer of each color changed by 50% of the initial-saturated chromaticity change amount can be obtained. Thereby, the optimal aging time can be obtained for the light emitting layers of each color.

The aging is performed for the longest time among the aging times obtained for the light emitting layers of each color. By performing aging in this manner, the chromaticity change is substantially saturated for the light emitting layers of all colors, and the chromaticity change after aging is substantially prevented.

Next, a specific example of the aging method of this embodiment and its effects will be described. For the organic EL element of this example, as in the first embodiment, the drive current is 1
A direct current of mA / cm ² was passed, and changes in luminance and chromaticity were measured under a high-temperature operating environment of 70 ° C.

First, with respect to the blue light emitting layer 35a, the light emission color was initially (0.18, 0.22) and 200 cd / m ² as CIE chromaticity coordinates and luminance, but after 150 hours. (0.190, 0.23), 12
0 cd / m ² , after 1000 hours (saturation of chromaticity)
(0.200, 0.240) and changed to 100 cd / m ² .

On the other hand, with respect to the red light emitting layer 35b, the emission color was initially (0.60, 0.32) and 300 cd / m ² as CIE chromaticity coordinates and luminance, but after 100 hours. (0.59, 0.33), 230
After 1000 hours (cd / m ² , chromaticity was saturated), it changed to (0.58, 0.34) and 160 cd / m ² .

Looking at the amount of change in initial-saturated chromaticity for each color, for example, the time required for the x-coordinate of chromaticity to change to 50% of the amount of change in initial-saturated chromaticity is 150 hours for blue and 150 hours for red. It is 100 hours, and the time required for the chromaticity change of the blue light emitting layer 35a to be smaller than that of the red light emitting layer 35b (light emitting time) is longer.

For this reason, in this example, by performing aging based on the chromaticity of the blue light emitting layer 35a, it is possible to prevent the entire color change. That is, if aging is performed so that the blue color is substantially saturated, the red color, in which the time required for the chromaticity change to be smaller than that of the blue color, is also saturated, is also saturated.

Specifically, in the organic EL device of this example, aging is performed until the x chromaticity coordinate of the blue light emitting layer 35a becomes a chromaticity changed to 50% of the initial-saturated chromaticity change amount. . The time for performing this aging is 1 under the above-mentioned 70 ° C. environment and a driving current of 1 mA / cm ^2.
Although it was 50 hours, in order to shorten the time, a driving current of 10 mA / cm ² was passed in an environment of 100 ° C., and aging was performed for 25 hours.

After passing through this aging process,
When a constant current drive of 1 mA / cm ² was performed in an environment of 70 ° C., the change in chromaticity of blue was changed to the initial chromaticity coordinates (0.19
0, 0.23) after driving for 1000 hours.
0, 0.240), and the red color change is
The initial chromaticity coordinates (0.588, 0.332) are 100
After driving for 0 hour, it stayed at (0.579, 0.342), and color change was substantially prevented. As described above, according to the third embodiment, the organic EL that can prevent the chromaticity change can be prevented.
A method for aging the device can be provided.

The present invention can be applied to an organic EL device having a light emitting layer whose chromaticity changes with the elapse of the light emitting time. In addition to the stacked arrangement or the planar arrangement type, the present invention can be applied to those having a monochromatic (single) light emitting layer.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an organic EL device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a configuration in which the organic EL element shown in FIG. 1 is sealed with a can member.

FIG. 3 is a diagram showing a state of chromaticity change in the organic EL element according to the first embodiment as a change in CIE chromaticity coordinates.

FIG. 4 is a diagram illustrating a change in chromaticity with respect to a light emission time in the organic EL element according to the first embodiment.

FIG. 5 is a diagram showing a light emission time required for the chromaticity to change by 10% of the initial-saturated chromaticity change amount in the organic EL device according to the first embodiment.

FIG. 6 is a graph showing a relationship between luminance and aging time in aging.

FIG. 7 is a graph showing a relationship between an ambient temperature and an aging time in aging.

FIG. 8 is a diagram illustrating a change in chromaticity with respect to a light emission time in an organic EL element according to a second embodiment of the present invention.

FIG. 9 is a schematic sectional view of an organic EL device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a change in a luminance balance and a change in a peak position in a mixed color emission spectrum.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... board | substrate, 20 ... anode, 30 ... organic layer, 31 ... hole transport layer, 32 ... light emitting layer, 32a ... hole transporting light emitting layer, 32
b: electron transporting light emitting layer, 33: electron transporting layer, 35a: blue light emitting layer, 35b: red light emitting layer, 40: cathode, 50: can member, 51: adhesive.

Claims (8)

[Claims] 1. An organic EL device having a light-emitting layer whose chromaticity changes with the lapse of light-emitting time, aging is performed by passing a current through the light-emitting layer such that the chromaticity of the light-emitting layer falls within a predetermined range. A method for manufacturing an organic EL device, wherein the device is shipped after aging. 2. An aging method for an organic EL element having a light emitting layer whose chromaticity changes with the elapse of a light emitting time, wherein the aging is performed by passing a current through the light emitting layer. However, when the chromaticity change amount from the initial chromaticity of the light emitting layer to the chromaticity at which the chromaticity change is saturated is assumed to be 100%, the chromaticity of the light emitting layer is equal to the chromaticity change amount. A method for producing an organic EL device, characterized in that it is a time until the chromaticity changes by at least 50%. 3. A light-emitting layer whose chromaticity changes with the lapse of light-emission time, and the chromaticity change characteristic of the light-emitting layer changes from an initial chromaticity to a chromaticity at which the chromaticity change is saturated. A method for aging an organic EL element, wherein the aging of the organic EL element having a value is performed by passing an electric current through the light emitting layer, wherein the aging time is changed from the initial chromaticity to the chromaticity of the light emitting layer. When the amount of time until the chromaticity of the light emitting layer reaches the extreme chromaticity and the amount of chromaticity change from the extreme chromaticity to the chromaticity at which the chromaticity change is saturated is 100%, the light emission is performed. The chromaticity of the layer is at least 50% of the chromaticity change
A method for manufacturing an organic EL device, wherein the total time is a time required until the chromaticity changes. 4. The light-emitting layer according to claim 1, wherein a plurality of layers emitting different emission colors are stacked, and a mixed color of the plurality of layers emits light.
4. The method for manufacturing an organic EL device according to any one of items 3 to 3. 5. The light emitting layer according to claim 1, wherein a plurality of layers emitting different emission colors are arranged in the same plane, and a mixed color of the plurality of layers emits light. The organic EL device according to claim 1.
Device manufacturing method. 6. The method according to claim 5, wherein a time for performing the aging is determined for each of the plurality of layers, and the aging is performed for a longest time among the determined times for performing the aging. The method for producing the organic EL device according to the above. 7. The method of manufacturing an organic EL device according to claim 1, wherein the aging is performed with a current having a luminance equal to or higher than a use luminance of the organic EL device. Method. 8. The method according to claim 1, wherein the aging is performed at a temperature equal to or higher than a use temperature of the organic EL element.
8. The method for manufacturing an organic EL device according to any one of items 7 to 7.