JP2004178986A - Organic el panel and its repairing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely realize self-repair of a picture element in an organic EL panel. <P>SOLUTION: In an organic panel having the picture element 50. which is provided with an organic layer 30 containing a luminescent layer 33 between a lower electrode 20 and an upper electrode 40, a reverse bias voltage of not more than the withstand voltage of the organic layer 30 under a voltage application condition in use is applied to the picture element. Preferably, a reverse bias voltage of not more than 1/2 of the withstand voltage of the organic layer 30 is applied to it. Therefore, the value of the reverse bias voltage for self-repair can be moderately determined with the withstand voltage of the organic layer under the voltage application condition in use as an index, and a defective part in the picture element 50 can be repaired by itself. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic electroluminescence (EL) panel and a method of repairing the same, and more particularly to an organic EL panel excellent in light emission stability in which display defects such as pixel defects and lines due to short-circuiting of upper and lower electrodes during use are suppressed.
[0002]
[Prior art]
The organic EL panel has pixels provided with an organic layer including a light emitting layer made of an organic EL material between a pair of electrodes, ie, a lower electrode and an upper electrode. The driving is performed by applying a pulse voltage to the pixel such that a forward bias voltage is applied during light emission and a reverse bias voltage is applied during non-emission.
[0003]
Since such an organic EL panel is self-luminous, it has excellent visibility, and can be driven at a low voltage of several V to several tens V, so that the weight including the driving circuit can be reduced. Therefore, it can be expected to be used as a thin film display, lighting, and backlight.
[0004]
However, since the organic EL panel uses an organic material, the organic material is liable to be deteriorated or mutually diffused by an electric field or heat, and as a result, a short circuit may occur between the upper and lower electrodes.
[0005]
Conventionally, as a countermeasure against this problem, there has been known a method in which a reverse pulse voltage (reverse bias voltage) is applied to anodize an upper electrode, which is an electron injection electrode, or to scatter the upper electrode to self-repair. (For example, see Patent Document 1). The basic concept of this technology is that only the upper electrode is scattered by the voltage energy of the reverse bias pulse.
[0006]
[Patent Document 1]
JP-A-11-162637 (page 3-6, FIG. 2-3)
[0007]
[Problems to be solved by the invention]
In the above-described conventional countermeasures against short-circuiting of the upper and lower electrodes, the parameters for determining the voltage applied for self-healing are determined by conditions such as the magnitude of the reverse bias voltage and its pulse width, and the thickness of the upper electrode Al. It has been.
[0008]
However, the present inventors have verified the above-described conventional technology and found that it is impossible to effectively realize self-repair with only these parameters.
[0009]
Specifically, when applying the reverse bias voltage of 35 V in the embodiment of Patent Document 1, the voltage energy of the reverse bias pulse is too large, and not only the defective portion of the pixel but also the entire upper electrode is scattered. It happened. Conversely, with a reverse bias voltage of 15 V, the upper electrode was not sufficiently scattered at the defective portion, self-repair did not effectively occur, and a short circuit occurred between the upper and lower electrodes.
[0010]
As described above, in the related art, a method of applying a reverse bias voltage to a pixel for the purpose of preventing a short circuit between the upper and lower electrodes has been proposed, but a reverse bias voltage application condition that can surely self-repair is determined. It was difficult.
[0011]
In view of the above problems, an object of the present invention is to provide an organic EL panel and a method for repairing the organic EL panel, which can reliably realize self-repair of pixels.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, as a result of diligent research, focusing on the withstand voltage of the organic layer, by adopting an element structure and a method of applying a reverse bias voltage corresponding to the withstand voltage, the self-healing effect can be effectively exhibited. It turned out to be possible. In other words, it has been found that the organic layer is involved in the scattering of the upper electrode, and is not limited to the scattering of the upper electrode.
[0013]
The breakdown voltage of the organic layer was defined as follows. Basically, it was the withstand voltage of the organic layer under the voltage application condition during use. The withstand voltage of the organic layer is the withstand voltage when a reverse bias voltage is applied from the principle of the organic EL panel. The breakdown voltage of the organic layer depends on the method of applying the reverse bias voltage.
[0014]
Therefore, in the evaluation of the withstand voltage, the reverse bias voltage should be set based on the voltage measured in the same state as the pulse width defined by the duty ratio, frequency, and the like in actual driving.
[0015]
For this reason, the withstand voltage of the organic layer is evaluated by applying a pulse voltage having a predetermined duty ratio and a pulse width to the pixel and causing a current to flow in the forward direction to emit light. The test was performed under the condition of voltage application during use (see FIG. 3).
[0016]
In this operation, while the forward current is kept constant (that is, the emission luminance is almost constant), the reverse bias voltage at which no light is emitted while the reverse bias voltage is increased is set as the breakdown voltage. The reverse bias voltage was changed by increasing the voltage by several volts while maintaining the voltage for 5 seconds or more and 1 minute or less for each voltage (see FIG. 4).
[0017]
When the reverse bias voltage is increased in this way, part or all of the upper electrode in the pixel scatters. The value of the reverse bias voltage at this time is defined as the breakdown voltage of the organic layer. According to this method, a substantially constant value can be obtained as the breakdown voltage of the organic layer under the voltage application condition during use.
[0018]
The present invention has been created by obtaining the breakdown voltage of the organic layer as described above in an organic EL panel and using the obtained breakdown voltage.
[0019]
According to the first aspect of the present invention, there is provided an organic EL panel having a pixel (50) including an organic layer (30) including a light emitting layer (33) between a lower electrode (20) and an upper electrode (40). When a reverse bias voltage lower than the withstand voltage of the organic layer under a voltage application condition during use is applied, the pixel can self-repair.
[0020]
According to this, the value of the reverse bias voltage for self-healing can be determined to be an appropriate value by using the breakdown voltage of the organic layer under the voltage application condition during use as an index. In other words, by setting the reverse bias voltage applied during non-light emission to a value equal to or less than the withstand voltage of the organic layer in the voltage applied during use, setting of an excessive reverse bias voltage such that the entire upper electrode is scattered. Can be prevented.
[0021]
In addition, since the breakdown voltage of the organic layer is used as an index, the magnitude of the reverse bias voltage is permissible below the breakdown voltage. Therefore, it is possible to prevent the self-healing from becoming insufficient due to the reverse bias voltage being too small.
[0022]
As described above, according to the present invention, it is possible to provide an organic EL panel that can realize self-repair of pixels more reliably than before in use.
[0023]
Here, the self-repairing referred to in the present invention means that a part of the upper electrode, specifically, a part of the upper electrode located above the defect part is scattered, and the upper and lower electrodes are electrically connected at the scattered part. Open, and no more defects spread.
[0024]
In other words, although some defects remain as pixels, the breakdown voltage of the pixels is restored, and light emission becomes possible. Furthermore, the phenomenon also includes a phenomenon in which a short circuit with the lower electrode is prevented by oxidizing the upper electrode remaining after the occurrence of the scattering and making it nonconductive.
[0025]
In the invention described in claim 2, the withstand voltage of the organic layer (30) is a withstand voltage when the organic layer (30) is driven for 1 minute or less under a voltage application condition during use.
[0026]
Although the withstand voltage of the organic layer decreases with the elapse of use time, it is preferable to adopt the withstand voltage at the beginning of use in order to exert the effect over the entire use. Such an initial withstand voltage can be a withstand voltage when the organic EL panel is driven for 1 minute or less under a voltage application condition during use.
[0027]
According to a third aspect of the present invention, the reverse bias voltage is not more than の of the withstand voltage of the organic layer (30).
[0028]
Even with the reverse bias voltage described in the first aspect, the upper electrode (40) of the entire pixel may be scattered depending on the element structure. Therefore, it is preferable to set the reverse bias voltage to be equal to or less than 1/2 of the withstand voltage of the organic layer (30). I knew it.
[0029]
In the invention according to claim 4, when the breakdown voltage of the organic layer (30) is represented by the electric field strength per unit thickness of the organic layer, the electric field strength is 3 × 10 ⁶ V / cm or more.
[0030]
It has been found that in the organic EL panel, the breakdown voltage of the organic layer can be defined by its total thickness regardless of the type of the organic material. The organic EL panel of the present invention has the electric field strength of 3 × 10 ⁶ V / cm or more. According to this, the effect of the above means can be effectively exhibited.
[0031]
In the invention according to claim 5, when the withstand voltage of the organic layer (30) is expressed by the electric field strength per unit thickness of the organic layer, when calculating the electric field strength, the conductive organic film is separated from the organic layer. When excluded, the electric field strength is 3.4 × 10 ⁶ V / cm or more.
[0032]
In an organic EL panel, when the thickness of a layer using a porphyrin-based conductive material typified by copper phthalocyanine is different in a panel to be compared, especially when the thickness is as large as about 30 nm or more, the electric field intensity becomes higher. May not be constant.
[0033]
In order to more accurately compare the electric field strength, it was found that it is more preferable to exclude the conductive organic film from the organic layer. In that case, if the electric field strength according to claim 4 is reviewed, 3.4 × 10 ⁶ V / cm or more.
[0034]
According to this, the effect of the above means can be effectively exhibited. An important concept here is that a porphyrin-based conductive material represented by copper phthalocyanine contributes as a resistor and is not a semiconductor (insulator) having a withstand voltage.
[0035]
In the invention according to claim 6, when the reverse bias voltage is Vr, the thickness of the upper electrode (40) is Da, and the ratio Vr / Da between Vr and Da is Xa, Xa is 2.2 × 10 ⁶ V / cm or more.
[0036]
If the reverse bias voltage is too small or the upper electrode is too thick, the upper electrode is less likely to scatter and self-repair is less likely. At this point, the ratio Vr / Da = Xa of the reverse bias voltage Vr and the thickness Da of the upper electrode is set to 2.2 × 10 ⁶ When V / cm or more, self-repair can be performed more appropriately (see FIG. 7), which is preferable.
[0037]
According to the seventh aspect of the present invention, the thickness Da of the upper electrode (40) is reduced to 100 nm or less, so that Xa is 2.2 × 10 2. ⁶ V / cm or more is ensured.
[0038]
As a method for realizing the value of Xa according to claim 6, it is better not to make the reverse bias voltage Vr too high. That is, as in the second aspect of the present invention, it is preferable that the breakdown voltage of the organic layer is about ２ or less.
[0039]
Therefore, it is preferable to realize the above-mentioned value of Xa by setting the reverse bias voltage to be low and reducing the thickness Da of the upper electrode to 100 nm or less. Setting the thickness Da to 100 nm or less means that the scattering shape of the upper electrode at the time of self-repair is measured by laser irradiation or the like, so that the scattering shape becomes a small and effectively electrically open shape. It is decided by examining Da.
[0040]
In the invention according to claim 8, when the reverse bias voltage is Vr, the thickness of the organic layer (30) is Dy, and the ratio Vr / Dy of these Vr and Dy is Ya, Ya is 1.2 × 10 ⁶ V / cm or more and 2.2 × 10 ⁶ V / cm or less.
[0041]
A small value of the ratio Ya indicates a case where the thickness Dy of the organic layer is large under the same reverse bias voltage, and a large value of the ratio Ya indicates a case where the thickness Dy of the organic layer is small. If the organic layer is too thick, self-healing is unlikely to occur because the organic layer is not easily scattered. On the other hand, if the organic layer is too thin, a uniform thickness of the organic layer cannot be realized due to the influence of the unevenness of the lower electrode and the like, so that the organic layer is scattered too much, causing a significant decrease in display quality, which is not preferable.
[0042]
In this regard, the ratio Vr / Dy = Ya of the reverse bias voltage Vr and the thickness Dy of the organic layer is set to 1.2 × 10 ⁶ V / cm or more and 2.2 × 10 ⁶ The range of V / cm or less is preferable because self-repair can be performed more appropriately (see FIG. 8).
[0043]
In the ninth aspect of the present invention, the reverse bias voltage is Vr, the thickness of the organic layer (30) excluding the conductive organic film is Dy ′, and the ratio Vr / Dy ′ between Vr and Dy ′ is Assuming that Ya ′, Ya ′ is 1.4 × 10 ⁶ Not less than V / cm and 2.4 × 10 ⁶ V / cm or less.
[0044]
According to a tenth aspect of the present invention, the pixel (50) is sealed with a gas containing 0.5% or more of a supporting gas.
[0045]
In order to effectively generate self-healing, a supporting gas such as oxygen may be used. Not only the scattering of the electrodes but also the oxidizing action (non-conductivity) of the electrodes makes it possible to more reliably open the electrical connection.
[0046]
An eleventh aspect of the present invention is characterized in that the lower electrode (20) has an average surface roughness Ra of 2 nm or less as a surface roughness.
[0047]
If the surface roughness of the lower electrode is rough, the distance between the upper and lower electrodes is partially reduced, the withstand voltage of the organic layer is also reduced, and self-repair is excessively generated, and defects such as disconnection of the upper electrode are likely to occur. In this regard, setting the average surface roughness Ra as the surface roughness of the lower electrode to 2 nm or less can easily avoid such a problem, which is preferable.
[0048]
According to the twelfth aspect of the present invention, an organic EL having a pixel (50) including an organic layer (30) including a light emitting layer (33) between a lower electrode (20) and an upper electrode (40). The method for repairing a panel is characterized in that pixels are self-repaired by applying a reverse bias voltage equal to or lower than the withstand voltage of the organic layer under voltage application conditions during use.
[0049]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the first aspect of the present invention.
[0050]
According to a thirteenth aspect of the present invention, as the withstand voltage of the organic layer (30), the withstand voltage when the organic layer (30) is driven for 1 minute or less under a voltage application condition during use is used.
[0051]
In the repair method according to the twelfth aspect, as in the invention according to the thirteenth aspect, when the organic EL panel is driven for one minute or less under the voltage application condition during use as the initial breakdown voltage, It can be withstand pressure.
[0052]
According to a fourteenth aspect of the present invention, as the reverse bias voltage, a voltage that is equal to or less than half the withstand voltage of the organic layer (30) is used.
[0053]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the invention according to claim 3.
[0054]
In the invention according to claim 15, when the breakdown voltage of the organic layer (30) is represented by the electric field strength per unit thickness of the organic layer, the electric field strength is 3 × 10 ⁶ An organic EL panel having a V / cm or more is used.
[0055]
According to this, it is possible to provide a repair method that can exhibit the same effect as the invention described in claim 4.
[0056]
In the invention according to claim 16, when the breakdown voltage of the organic layer (30) is expressed by the electric field strength per unit thickness of the organic layer, the conductive organic film is excluded from the organic layer when calculating the electric field strength. Then, the electric field intensity is 3.4 × 10 ⁶ An organic EL panel having a V / cm or more is used.
[0057]
According to this, it is possible to provide a repair method that can exhibit the same effect as the invention described in claim 5.
[0058]
In the invention according to claim 17, when the reverse bias voltage is Vr, the thickness of the upper electrode (40) is Da, and the ratio Va / Da between Vr and Da is Xa, Xa is 2.2 × 10 ⁶ V / cm or more.
[0059]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the invention described in claim 6.
[0060]
According to the eighteenth aspect of the present invention, the thickness Da of the upper electrode (40) is reduced to 100 nm or less so that Xa is 2.2 × 10 2. ⁶ V / cm or more.
[0061]
According to this, it is possible to provide a repair method that can exhibit the same effect as the invention described in claim 7.
[0062]
According to the nineteenth aspect, when the reverse bias voltage is Vr, the thickness of the organic layer (30) is Dy, and the ratio Va / Dy between Vr and Dy is Ya, Ya is 1.2 × 10 ⁶ V / cm or more and 2.2 × 10 ⁶ V / cm or less.
[0063]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the invention described in claim 8.
[0064]
In the twentieth aspect, the reverse bias voltage is Vr, the thickness of the organic layer (30) excluding the conductive organic film is Dy ′, and the ratio Vr / Dy ′ between Vr and Dy ′ is Assuming that Ya ′, Ya ′ is 1.4 × 10 ⁶ Not less than V / cm and 2.4 × 10 ⁶ V / cm or less.
[0065]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the invention described in claim 9.
[0066]
According to a twenty-first aspect of the present invention, self-repair is performed while the pixel (50) is sealed with a gas containing 0.5% or more of a supporting gas.
[0067]
According to this, it is possible to provide a repair method that can exhibit the same effect as the invention described in claim 10.
[0068]
The invention according to claim 22 is characterized in that the lower electrode (20) having an average surface roughness Ra of 2 nm or less is used.
[0069]
According to this, it is possible to provide a repair method capable of exhibiting the same effect as the invention described in claim 11.
[0070]
It should be noted that reference numerals in parentheses of the above-described units are examples showing the correspondence with specific units described in the embodiments described later.
[0071]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 1 is a diagram showing a schematic sectional configuration of an organic EL panel S1 according to an embodiment of the present invention. In the organic EL panel S1, a lower electrode 20, an organic layer 30 including a light emitting layer 33, and an upper electrode 40 are sequentially formed on an insulating substrate 10 such as glass or resin.
[0072]
Here, the upper and lower electrodes 20 and 40 and the organic layer 30 in a region 50 where the lower electrode 20 and the upper electrode 40 overlap each other are formed as pixels 50. Here, FIG. 2 is a diagram showing an example of a schematic plan configuration of the organic EL panel S1 shown in FIG.
[0073]
In this example, as shown in FIG. 2, the electrodes 20 and 40 have a stripe shape orthogonal to each other, and the intersection of the stripe electrodes 20 and 40 is a pixel 50. Each of the pixels 50 has a size of 0.3 mm square and constitutes a 256 × 64 dot matrix.
[0074]
The lower electrode 20 is made of an optically transparent ITO (Indium Tin Oxide) film or the like. In the present embodiment, the organic layer 30 includes a hole injection layer 31 made of a hole injection organic material or the like, a hole transport layer 32 made of a hole transport organic material or the like, a hole transport property or an electron transport property. A light-emitting layer 33 made of a material containing a light-emitting dye in the organic material described above and an electron transport layer 34 made of an electron-transport organic material are sequentially laminated.
[0075]
Each of the layers 31, 32, 33, and 34 constituting the organic layer 30 may be formed of a plurality of layers made of different materials. For example, as shown by a broken line in FIG. 1, the light emitting layer 33 may be composed of two layers 33a and 33b, and the electron transport layer 34 may be composed of two layers 34a and 34b.
[0076]
The upper electrode 40 is made of a metal film such as Al. To each of the layers constituting the pixels 50, a material used for a normal organic EL panel or a material that can be used can be applied. Such an organic EL panel S1 can be manufactured by sequentially forming the layers 20 to 40 on the substrate 10 by using a sputtering method, a vacuum evaporation method, or the like.
[0077]
The organic EL panel S1 is driven by applying a voltage between the upper and lower electrodes 20, 40 using the lower electrode 20 as an anode and the upper electrode 40 as a cathode. At this time, the pixel 50 emits light by applying a forward bias voltage during light emission, and applies a reverse bias voltage during non-emission to suppress light emission due to crosstalk or the like.
[0078]
Specifically, in the dot matrix type organic EL panel S1 of this example, a pulse voltage having a drive waveform having a predetermined duty ratio and a predetermined pulse width as shown in FIG. . The light emitting layer 33 emits light when a forward bias voltage (forward pulse) is applied, and enters a non-light emitting state when a reverse bias voltage (reverse bias pulse) is applied.
[0079]
[Self-healing action of the organic EL panel]
The driving waveform as shown in FIG. 3 is a voltage application condition during use in the organic EL panel. In the present embodiment, a reverse bias voltage equal to or lower than the withstand voltage of the organic layer 30 under the voltage application condition during use is applied. Sometimes, the pixel 50 is capable of self-repair.
[0080]
The withstand voltage of the organic layer is determined based on a voltage measured in the same state as a pulse width defined by a duty ratio, a frequency, and the like in actual driving. That is, in the driving waveform shown in FIG. 3, the reverse bias voltage at which no light is emitted while the magnitude of the reverse bias voltage is increased while the forward current remains constant (that is, the light emission luminance is substantially constant) is defined as the breakdown voltage.
[0081]
Here, as a method of changing the reverse bias voltage, as shown in FIG. 4, a method of increasing the voltage by several volts while keeping the holding time for each voltage at 5 seconds or more and 1 minute or less. As described above, when the reverse bias voltage is increased, part or all of the upper electrode 40 in the pixel 50 is scattered. The value of the reverse bias voltage when this scattering occurs is defined as the breakdown voltage of the organic layer 30.
[0082]
According to this method, a substantially constant value can be obtained as the breakdown voltage of the organic layer under the voltage application condition during use. Although not limited, in this example, the breakdown voltage of the organic layer 30 is increased by increasing the forward bias voltage to 10 V and increasing the holding time at each reverse bias voltage by 5 V for each second from 20 V by 1 V. You can ask.
[0083]
Furthermore, since the organic EL panel S1 of this example has a plurality of pixels 50, the breakdown voltage of the organic layer 30 in each pixel 50 has a certain distribution. Specifically, in this example, as a result of examining the withstand voltage of the organic layer 30 for the plurality of pixels 50, the distribution as shown in FIG. 5 was obtained. The withstand voltage of the organic layer 30 in this example is an average value, that is, an average withstand voltage (50 V in FIG. 5).
[0084]
In this manner, in the organic EL panel S1 in which the withstand voltage of the organic layer 30 is defined under the voltage application condition during use, in this embodiment, when a reverse bias voltage equal to or lower than the withstand voltage of the organic layer 30 is applied, the pixel 50 are self-healing.
[0085]
According to this, the value of the reverse bias voltage for self-healing can be determined to an appropriate value by using the breakdown voltage of the organic layer 30 under the voltage application condition during use as an index. That is, under the voltage condition applied during use (see FIG. 3 above), the entire upper electrode 40 is scattered by setting the reverse bias voltage applied during non-light emission to be equal to or smaller than the withstand voltage of the organic layer 30. Setting of such an excessive reverse bias voltage can be prevented.
[0086]
Then, even if the reverse bias voltage is smaller than the withstand voltage of the organic layer 30, the self-healing can be sufficiently performed. This is because the portion of the pixel 50 to be self-repaired is a defective portion, so that even if a reverse bias voltage lower than the withstand voltage of the organic layer 30 is applied, the upper electrode 40 above the defective portion is scattered. This is presumably because voltage energy and Joule heat can be generated.
[0087]
In addition, since the breakdown voltage of the organic layer 30 is used as an index, the magnitude of the reverse bias voltage is allowable as far as the breakdown voltage or less. Therefore, it is possible to prevent the self-healing from becoming insufficient due to the reverse bias voltage being too small.
[0088]
As described above, according to the present embodiment, it is possible to provide an organic EL panel and a method for repairing such an organic EL panel that can more reliably realize self-repair of pixels during use than before.
[0089]
6A and 6B are cross-sectional views schematically illustrating an example of the self-repair according to the present embodiment. FIG. 6A shows that the defect K1 scatters to a part of the lower electrode 20 in addition to the upper electrode 40 and the organic layer 30, and the upper and lower electrodes 20 and 40 are electrically opened to be self-repaired. It is an example. FIG. 6B shows an example in which the upper and lower electrodes 20 and 40 are electrically opened in a state where a part 30 ′ of the organic layer 30 remains, and is thus self-repaired.
[0090]
The self-repair as shown in FIG. 6 is performed, for example, as follows. In the pixel 50 in use (during driving), when a minute breakdown point due to a short circuit occurs as the defective portion K1, voltage energy and Joule heat are generated in the defective portion K1 by application of a self-repairable reverse bias voltage.
[0091]
As a result, the upper electrode 40 blows upward and retreats outward from the end of the defective portion K1, so that the portion where the upper electrode 40 is lost becomes larger than the diameter of the defective portion K1. For this reason, the upper electrode 40 does not exist at the end of the defective portion K1, and the upper and lower electrodes 20 and 40 are electrically open at that portion, and the defect does not further advance to the surroundings.
[0092]
In other words, although some defects remain as the pixel 50, the withstand voltage of the pixel 50 is restored, and self-repair is performed by enabling light emission. Further, the self-repairing also includes a phenomenon (not shown) in which the surface of the upper electrode 40 remaining after the occurrence of the scattering is oxidized and rendered nonconductive, thereby preventing a short circuit with the lower electrode 20. In this case, even if the scattering of the upper electrode 40 is insufficient to some extent and the upper electrode 40 hangs down toward the lower electrode 20, a short circuit is prevented.
[0093]
Further, as described above with reference to FIG. 4, in the present embodiment, the withstand voltage of the organic layer 30 is a withstand voltage when the organic layer 30 is driven for 1 minute or less under a voltage application condition during use. That is, it means that the holding time in FIG. 4 is set to 1 minute or less and the withstand voltage of the organic layer 30 is obtained.
[0094]
Since the withstand voltage of the organic layer 30 decreases with the elapse of the use time, it is preferable to adopt the withstand voltage in the initial use in order to exert the effect from the initial use to a long time, that is, over the entire use. It is clear. Such an initial withstand voltage can be a withstand voltage when the organic EL panel is driven for 1 minute or less under a voltage application condition during use.
[0095]
[Preferred Means]
Next, preferred means in the present embodiment will be described. In the organic EL panel S1 and the repair method according to the present embodiment, it is preferable that the reverse bias voltage under the voltage application condition during use has a relationship of not more than １ ／ of the withstand voltage of the organic layer 30.
[0096]
Even if the reverse bias voltage is lower than the withstand voltage of the organic layer 30, the upper electrode 40 of the entire pixel 50 may be scattered depending on the element structure. On the other hand, if the reverse bias voltage is set to 以下 or less of the withstand voltage of the organic layer 30, it is possible to ensure that the upper electrode 40 can be scattered only at the portion to be self-repaired regardless of the element structure.
[0097]
Further, as described above, the breakdown voltage of the organic layer 30 has a distribution due to manufacturing variations among the plurality of pixels 50 and variations among manufacturing lots. The breakdown voltage of 30 was examined, and the average breakdown voltage was adopted. On the other hand, if the reverse bias voltage is suppressed to half or less of the withstand voltage of the organic layer 30, it is easy to prevent the upper electrode 40 from scattering too much in the pixels that are out of the average value.
[0098]
In the organic EL panel S1 and the repair method of the present embodiment, when the breakdown voltage of the organic layer 30 is represented by the electric field intensity per unit thickness of the organic layer 30, the electric field intensity is 3 × 10 ⁶ V / cm or more is preferable.
[0099]
According to the study by the present inventors, it has been found that in the organic EL panel, the breakdown voltage of the organic layer 30 can be defined by its total thickness regardless of the type of the organic material (see FIG. 10 described later). For the organic EL panel S1, the electric field intensity is 3 × 10 ⁶ V / cm or more, whereby the effects of the present embodiment described above can be effectively exhibited.
[0100]
More preferably, the conductive organic film is excluded from the organic layer 30 when calculating the electric field strength, and the electric field strength is 3.4 × 10 ⁶ V / cm or more. According to this, the effects of the present embodiment described above can be effectively exhibited.
[0101]
In the organic EL panel S1 and the repair method of the present embodiment, when the reverse bias voltage is Vr, the thickness of the upper electrode 40 is Da, and the ratio Vr / Da between Vr and Da is Xa, Xa (= Vr / Da) value is 2.2 × 10 ⁶ It is preferably at least V / cm.
[0102]
If the reverse bias voltage is too small or the upper electrode 40 is too thick, the upper electrode 40 is hardly scattered and self-repair is difficult. That is, if the value of Xa (= Vr / Da) is too small, self-healing is difficult. Then, the present inventors examined the relationship between the ratio Vr / Da = Xa and the short-circuit rate of the upper and lower electrodes 20 and 40 in the organic EL panel S1. FIG. 7 shows the result.
[0103]
In FIG. 7, the short-circuit rate of the upper and lower electrodes is such that the short-circuit portion of the upper and lower electrodes 20 and 40 is not self-repaired after the endurance time as a use time is 1000 hours, that is, after driving the organic EL panel S1 for 1000 hours. (For example, a line defect).
[0104]
From FIG. 7, the ratio Vr / Da = Xa is 2.2 × 10 ⁶ If it is less than V / cm, the upper electrode 40 is too thick or the reverse bias voltage is too small, so that the scattering of the upper electrode 40 is insufficient and self-repair is difficult, but the ratio Vr / Da = Xa is not satisfied. 2.2 × 10 ⁶ It can be seen that self-healing can be appropriately performed if the value is V / cm or more.
[0105]
Further, this ratio Xa (= Vr / Da) is set to 2.2 × 10 ⁶ It is preferable to secure V / cm or more by reducing the thickness Da of the upper electrode 40 to 100 nm or less.
[0106]
This is because it is better not to make the reverse bias voltage Vr too high as a technique for realizing the value of the ratio Xa. That is, as described above, it is preferable to suppress the reverse bias voltage Vr to about 1/2 or less of the withstand voltage of the organic layer 30 as much as possible.
[0107]
Therefore, it is preferable to realize the above-mentioned value of Xa by setting the reverse bias voltage to a lower value and reducing the thickness Da of the upper electrode 40 to 100 nm or less. Setting the thickness Da to 100 nm or less means that the scattering shape of the upper electrode 40 at the time of self-repair is measured by laser irradiation or the like, so that the scattering shape becomes a small and effectively electrically open shape. This is determined by examining the thickness Da.
[0108]
In the organic EL panel S1 and the repair method of the present embodiment, when the reverse bias voltage is Vr, the thickness of the organic layer 30 is Dy, and the ratio Vr / Dy between Vr and Dy is Ya, The ratio Ya is 1.2 × 10 ⁶ V / cm or more and 2.2 × 10 ⁶ It is preferably at most V / cm.
[0109]
A small value of the ratio Ya indicates a case where the thickness Dy of the organic layer 30 is large when considered at the same reverse bias voltage, and a large value of the ratio Ya indicates a case where the thickness Dy of the organic layer 30 is small. .
[0110]
If the organic layer 30 is too thick, the organic layer 30 is less likely to scatter and self-repair is less likely to occur. On the other hand, if the organic layer 30 is too thin, the uniform thickness of the organic layer 30 cannot be realized due to the influence of the unevenness of the lower electrode 20, so that the organic layer 30 is scattered too much, causing a significant reduction in display quality. Not preferred.
[0111]
Then, the present inventors examined the relationship between the ratio Vr / Da = Ya and the short-circuit rate of the upper and lower electrodes 20 and 40 in the organic EL panel S1 of the present embodiment. FIG. 8 shows the result.
[0112]
In FIG. 8, the short-circuit rate of the upper and lower electrodes is defined the same as in FIG. From FIG. 8, the ratio Vr / Da = Ya is 1.2 × 10 ⁶ In the case of less than V / cm, it is understood that the organic layer 30 is too thick or the reverse bias voltage is too small, so that the organic layer 30 and the upper electrode 40 are not sufficiently scattered and self-repair is difficult.
[0113]
On the other hand, the ratio Vr / Da = Ya is 2.2 × 10 ⁶ When it is larger than V / cm, the organic layer 30 is too thin and the organic layer 30 is scattered too much, which causes a significant decrease in display quality, which is not preferable. From such a study result, the ratio Vr / Da = Ya was set to 1.2 × 10 ⁶ V / cm or more and 2.2 × 10 ⁶ It has been found that self-healing can be appropriately performed at a V / cm or less.
[0114]
Further, in the organic EL panel S1 and the repair method of the present embodiment, it is preferable that the pixels 50 be sealed with a gas containing 0.5% or more of a combustible gas such as oxygen.
[0115]
This is not specifically illustrated, but the upper part of the organic EL panel S1 is sealed with a sealing can filled with a gas such as dry nitrogen containing a supporting gas such as oxygen of 0.5% or more. Can be realized.
[0116]
In order to effectively generate self-healing, a supporting gas such as oxygen may be used. According to this, not only the scattering of the upper electrode 40 but also the oxidizing action (non-conductivity) of the upper electrode 40 can more reliably open the electrical connection, which is preferable.
[0117]
In the organic EL panel S1 and the repair method of the present embodiment, it is preferable that the lower electrode 20 has a surface roughness of 2 nm or less in average surface roughness Ra.
[0118]
Specifically, when the lower electrode 20 serving as a base is made of ITO, smoothing can be achieved by polishing the ITO by buff polishing or the like after the formation of the ITO. More preferably, it is necessary to prevent the organic layer 30 from becoming thinner at the edge of the lower electrode 20, such as by polishing after patterning the ITO.
[0119]
If the surface roughness of the lower electrode 20 is rough, the distance between the upper and lower electrodes 20 and 40 is partially reduced. As a result, the withstand voltage of the organic layer 30 is also reduced, and self-repair occurs too much and the upper electrode 40 is disconnected. Is likely to occur. In this regard, setting the average surface roughness Ra of the lower electrode 20 to 2 nm or less is preferable because such a problem can be easily avoided.
[0120]
Next, the present embodiment will be described more specifically with reference to specific examples 1 to 5 as examples below.
[0121]
FIG. 9 shows the lower electrode surface roughness Ra (nm), the organic layer thickness Dy (nm), the upper electrode (cathode) thickness Da, and the reverse bias voltage Vr of the organic EL panel S1 used in each of Examples 1 to 5. 5 is a table showing (V), the withstand voltage Vd (V) of the organic layer, the electric field strength Vd / Dy (V / cm) of the withstand voltage of the organic layer, the above-described ratio Xa, ratio Ya, and the like.
[0122]
In the following specific examples, the electric field intensity per unit thickness of the organic layer when the withstand voltage Vd of the organic layer (30) is divided by the organic layer thickness Dy ′ (nm) excluding the conductive organic film is shown. Vd / Dy ′ (V / cm) and Ya ′ (V / cm) which is the ratio Vr / Dy ′ of the reverse bias voltage Vr to the thickness Dy ′ of the organic layer 30 excluding the conductive organic film. Indicated.
[0123]
[Specific example 1]
In this example, the substrate 10 was a glass substrate, the lower electrode (anode) 20 was an ITO film having a thickness of about 150 nm formed by a sputtering method, and was configured as a hole injecting electrode, that is, an anode. The surface of the lower electrode 20 was polished to Ra = 1.2 nm.
[0124]
The organic layer 30 of this example was formed by a vacuum evaporation method after pre-treatment of the ITO surface with UV ozone, and then placed in a vacuum chamber. First, copper phthalocyanine (CuPc) is deposited to a thickness of 15 nm as a hole injection layer 31, α-naphthyl phenyl benzene is deposited to a thickness of 50 nm as a hole transport layer 32, and coumarin is deposited as a light emitting layer 33. Aluminum quinolinol doped with 1% was deposited to a thickness of 40 nm, and as the electron transport layer 34, aluminum quinolinol was deposited to a thickness of about 30 nm. In this case, the emission color is green.
[0125]
Further, as the upper electrode (cathode) 40, LiF was deposited in a thickness of 0.5 nm and Al was deposited in a thickness of 80 nm. Then, the panel was placed in a dry nitrogen atmosphere having a dew point of -70 ° C., and 1% oxygen was introduced as a combustible gas, and the panel was sealed with a sealing can.
[0126]
When the organic EL panel S1 was driven at 120 Hz with a duty ratio of 1/64, the withstand voltage Vd of the organic layer 30 was 50V. Note that the withstand voltage of 50 V of the organic layer 30 in this example corresponds to the average withstand voltage shown in FIG. The withstand voltage of the organic layer 30 is 3.7 × 10 in electric field intensity Vd / Dy per unit thickness of the organic layer 30. ⁶ V / cm.
[0127]
When the thickness of the copper phthalocyanine (CuPc) of the hole injection layer 31 which is a conductive organic film is 15 nm, the electric field intensity Vd / Dy ′ is 4.2 × 10 ⁶ V / cm.
[0128]
For driving, the forward pulse (forward bias voltage) is driven at a constant current so that the duty ratio is 1/64, and the initial luminance is 200 cd / m2. ² It was adjusted to be. The voltage of the forward pulse at that time was about 10V. At times other than the forward direction pulse, a reverse bias pulse of 20 V was applied as a reverse bias voltage.
[0129]
At this time, the ratio Xa (= Vr / Da) is 2.5 × 10 ⁶ V / cm, and Ya (= Vr / Dy) is 1.48 × 10 ⁶ V / cm. Ya ′ (= Vr / Dy ′) is 1.7 × 10 ⁶ V / cm.
[0130]
When the durability of the organic EL panel S1 was evaluated, even when the device was operated at a high temperature of 80 ° C., no trouble such as a line defect or a short circuit of the upper and lower electrodes 20, 40 occurred at all for more than 1000 hours, and the self-repair was properly performed. confirmed. Incidentally, as a comparative example, when a reverse bias voltage exceeding a withstand voltage of 50 V of the organic layer 30 was applied and the organic layer 30 was similarly driven and evaluated for durability, a line defect occurred within 100 hours.
[0131]
In addition, although the oxygen concentration in the sealing can in Example 1 was set to 1%, it has been confirmed that if the oxygen concentration is 0.5% or more, it is effective in oxidizing (passivating) the upper electrode 40.
[0132]
Here, a modified example of the first specific example will be described. In the first modification, 2.5 × 10 which is Xa (= Vr / Da) of the first specific example is used. ⁶ The same panel S1 as in Example 1 was driven at a reverse bias voltage of 13 V (Xa = 1.6 × 10 ⁶ V / cm).
[0133]
As a result, in the high-temperature operation, no line defect occurred due to a short circuit between the upper and lower electrodes 20 and 40 for up to 200 hours. This indicates that the self-healing effect was smaller than that of the specific example 1, but the self-healing effect was higher than that of the comparative example.
[0134]
In the second modification, the reverse bias voltage is higher than the reverse bias voltage of 20 V with respect to the breakdown voltage of 50 V of the organic layer 30 of the first embodiment. (Xa = 3.1 × 10) ⁶ V / cm).
[0135]
As a result, in the high-temperature operation, no line defect occurred due to a short circuit between the upper and lower electrodes 20 and 40 for up to 700 hours. This indicates that the self-healing effect was smaller than that of the specific example 1, but the self-healing effect was higher than that of the comparative example.
[0136]
In the third modification, 2.5 × 10 which is Xa (= Vr / Da) of the first specific example is used. ⁶ V / cm, which was set to lower Xa. In the same panel S1 as in Example 1, the thickness of the upper electrode 40 was reduced to 130 nm, and the panel was driven with a reverse bias voltage of 20 V (Xa = 1.53 × 10 3 ⁶ V / cm).
[0137]
As a result, in the high-temperature operation, no line defect occurred due to a short circuit between the upper and lower electrodes 20 and 40 for up to 600 hours. This indicates that the self-healing effect was smaller than that of the specific example 1, but the self-healing effect was higher than that of the comparative example.
[0138]
[Example 2]
In the present specific example 2, a white light emitting element was used, the organic layer 30 was thicker, and the upper electrode (cathode) was thinner than the specific example 1 (see FIG. 9).
[0139]
An ITO film having a thickness of about 320 nm was formed as an upper electrode (anode) 20 on the glass substrate 10. The surface of the ITO film was polished to Ra = 1.2 nm. Then, after pretreatment of the ITO surface with UV ozone, it was placed in a vacuum chamber.
[0140]
In the organic layer 30 of this example, first, copper phthalocyanine (CuPc) was formed to a thickness of 15 nm as the hole injection layer 31, and a tertiary amine tetramer was formed to a thickness of 57 nm as the hole transport layer 32 thereon.
[0141]
The light emitting layer 33 has a two-layer structure of a yellow light emitting layer 33a and a blue light emitting layer 33b in order from the hole transport layer 32 side, and emits white light as a mixed color. In this example, a tertiary amine tetramer doped with 6% rubrene was deposited to a thickness of 1 nm as the yellow light emitting layer 33a, and an adamantane derivative doped with 5% perylene was deposited to a thickness of 40 nm as the blue light emitting layer 33b.
[0142]
Next, in this example, the electron transport layer 34 has a two-layer structure of a first electron transport layer 34a and a second electron transport layer 34b in order from the light emitting layer 33 side. A non-doped layer of an adamantane derivative was formed to a thickness of 20 nm as the first electron transport layer 34a, and aluminum quinolinol was formed to a thickness of about 10 nm as the second electron transport layer 34b.
[0143]
Further, as the upper electrode (cathode) 40, LiF was deposited in a thickness of 0.5 nm and Al was deposited in a thickness of 70 nm. Then, the panel was placed in a dry nitrogen atmosphere having a dew point of -70 ° C., and 1% oxygen was introduced as a combustible gas, and the panel was sealed with a sealing can.
[0144]
When the organic EL panel S1 was driven at 120 Hz with a duty ratio of 1/64, the withstand voltage Vd of the organic layer 30 was 53V. The withstand voltage of the organic layer 30 is 3.7 × 10 in electric field intensity Vd / Dy per unit thickness of the organic layer 30. ⁶ V / cm.
[0145]
When the thickness of the copper phthalocyanine (CuPc) of the hole injection layer 31 which is a conductive organic film is 15 nm, the electric field strength Vd / Dy ′ is 4.1 × 10 ⁶ V / cm.
[0146]
For driving, the forward pulse (forward bias voltage) is driven at a constant current so that the duty ratio is 1/64, and the initial luminance is 200 cd / m2. ² It was adjusted to be. The voltage of the forward pulse at that time was about 11V. At times other than the forward direction pulse, a reverse bias pulse of 20 V was applied as a reverse bias voltage.
[0147]
At this time, the ratio Xa (= Vr / Da) is 2.85 × 10 ⁶ V / cm, and Ya (= Vr / Dy) is 1.4 × 10 ⁶ V / cm. Ya ′ (= Vr / Dy ′) is 1.6 × 10 ⁶ V / cm.
[0148]
When the durability of this organic EL panel S1 was evaluated, even at a high temperature operation of 80 ° C., no problem such as a line defect or a short circuit of the upper and lower electrodes 20 and 40 occurred at all for 1500 hours or more, and the self-repair was properly performed. confirmed. In the present specific example 2, it is considered that the self-healing function was further enhanced by increasing the ratio Xa.
[0149]
[Specific example 3]
In the specific example 3, the surface roughness of the ITO film as the lower electrode 20 is larger and the upper electrode 40 is thinner than the specific example 1 (see FIG. 9).
[0150]
In the organic EL panel S1 of this example, the surface roughness Ra of the ITO film was 1.8 nm based on the panel of the above-described specific example 1.
[0151]
It is considered that the withstand voltage of the organic layer 30 is lowered by increasing the surface roughness of the lower electrode 20, but the organic EL panel S1 is actually driven at 120 Hz with a 1/64 duty ratio. The withstand voltage Vd of the layer 30 was 40.5V. The withstand voltage of the organic layer 30 is 3.0 × 10 in electric field intensity Vd / Dy per unit thickness of the organic layer 30. ⁶ V / cm. The electric field intensity Vd / Dy 'is 3.4 × 10 ⁶ V / cm.
[0152]
Further, in the present example, when driving at a duty ratio of 120 Hz and 1/64, which is the same as the specific example 1, even if a reverse bias voltage of 16.5 V is applied, the ratio Xa (= Vr / Da) is 2 .2 × 10 ⁶ The thickness Da of the upper electrode (cathode) 40 was set to 60 nm so as to secure V / cm or more. In this example, Ya (= Vr / Dy) is 1.2 × 10 ⁶ V / cm. Ya ′ (= Vr / Dy ′) is 1.4 × 10 ⁶ V / cm.
[0153]
When the durability of the organic EL panel S1 was evaluated, even when the device was operated at a high temperature of 80 ° C., no trouble such as a line defect or a short circuit of the upper and lower electrodes 20, 40 occurred at all for more than 1000 hours, and the self-repair was properly performed. confirmed.
[0154]
[Example 4]
In the specific example 4, the surface roughness of the ITO film as the lower electrode 20 is smaller and the organic layer 30 is thinner than the specific example 1 (see FIG. 9).
[0155]
The organic EL panel S1 of this example is based on the panel of the above-described specific example 1, and the hole transport is performed by reducing the surface roughness Ra of the ITO film to 0.6 nm and keeping the thickness of the hole injection layer 31 at 15 nm. The thickness of the layer 32 was reduced to 30 nm, the thickness of the light emitting layer 33 was reduced to 30 nm, and the thickness of the electron transport layer 34 was reduced to 10 nm.
[0156]
When the organic EL panel S1 was driven at 120 Hz at a duty ratio of 1/64, the withstand voltage Vd of the organic layer 30 was 30V. The withstand voltage of the organic layer 30 is 3.5 × 10 in electric field intensity Vd / Dy per unit thickness of the organic layer 30. ⁶ V / cm. The electric field strength Vd / Dy 'is 4.3 × 10 ⁶ V / cm.
[0157]
Further, in this example, when driving at a duty ratio of 120 Hz and 1/64, which is the same as in the specific example 1, even if a reverse bias voltage of 14 V is applied, the ratio Xa (= Vr / Da) is 2.2. × 10 ⁶ The thickness Da of the upper electrode (cathode) 40 was set to 60 nm so as to secure V / cm or more. In this example, Ya (= Vr / Dy) is 1.6 × 10 ⁶ V / cm. Ya ′ (= Vr / Dy ′) is 2.0 × 10 ⁶ V / cm.
[0158]
When the durability of the organic EL panel S1 was evaluated, even when the device was operated at a high temperature of 80 ° C., no trouble such as a line defect or a short circuit of the upper and lower electrodes 20, 40 occurred at all for more than 1000 hours, and the self-repair was properly performed. confirmed.
[0159]
[Example 5]
In the specific example 5, the withstand voltage of the organic layer 30 is changed by changing the duty ratio in the applied driving voltage as compared with the specific example 1 (see FIG. 9).
[0160]
The withstand voltage of the organic layer 30 when driven at 120 Hz with a duty ratio of 1/32 using the same organic EL panel S1 as in the above example 1 was 46 V, which was smaller than that in the example 1. The withstand voltage Vd of the organic layer 30 is 3.4 × 10 in the electric field strength Vd / Dy per unit thickness of the organic layer 30. ⁶ V / cm. The electric field strength Vd / Dy 'is 3.8 × 10 ⁶ V / cm.
[0161]
For driving, the forward pulse (forward bias voltage) is driven at a constant current so that the duty ratio is 1/32, and the initial luminance is 200 cd / m2. ² It was adjusted to be. The voltage of the forward pulse at that time was about 8V. At times other than the forward pulse, a reverse bias pulse of 18 V was applied as a reverse bias voltage.
[0162]
At this time, the ratio Xa (= Vr / Da) is 2.3 × 10 ⁶ V / cm, and Ya (= Vr / Dy) is 1.33 × 10 ⁶ V / cm. Ya ′ (= Vr / Dy ′) is 1.5 × 10 ⁶ V / cm.
[0163]
When the durability of the organic EL panel S1 was evaluated, even when the device was operated at a high temperature of 80 ° C., no trouble such as a line defect or a short circuit of the upper and lower electrodes 20, 40 occurred at all for more than 1000 hours, and the self-repair was properly performed. confirmed.
[0164]
In each of the above specific examples 1 to 5, the electric field strength per unit thickness of the organic layer 30 is 3 × 10 ⁶ V / cm or more. FIG. 10 is a diagram showing the relationship between the thickness (nm) of the organic layer 30 and the average withstand voltage (V) of the organic layer 30 examined by the present inventors, and the electric field strengths of the specific examples 1 to 5 are also plotted. I have.
[0165]
As shown in FIG. 10, according to the study of the present inventors, it has been found that in the organic EL panel, the breakdown voltage of the organic layer 30 can be defined by the total thickness thereof regardless of the type of the organic material. . And 3 × 10 ⁶ In the specific examples 1 to 5 in which the electric field strength is not less than V / cm, the self-repair effect is sufficiently exhibited.
[0166]
(Other embodiments)
It should be noted that the organic EL panel may be composed of one pixel other than a panel having a plurality of pixels 50 such as a dot matrix type. In this case, the withstand voltage of the organic layer may be determined as an average withstand voltage using a plurality of panels having the same configuration.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an organic EL panel according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of a schematic plan configuration of the organic EL panel shown in FIG.
FIG. 3 is a diagram illustrating an example of a driving waveform as a voltage application condition when the organic EL panel is used.
FIG. 4 is a diagram showing a method of increasing a reverse bias voltage in order to determine a breakdown voltage of an organic layer.
FIG. 5 is a diagram illustrating an example of a breakdown voltage distribution based on a result of examining a breakdown voltage of an organic layer for a plurality of pixels.
FIG. 6 is a sectional view schematically showing an example of self-repair according to the embodiment.
FIG. 7 is a diagram showing a result of examining a relationship between a ratio Va / Da of a reverse bias voltage Vr and an upper electrode thickness Da and a short-circuit rate of upper and lower electrodes.
FIG. 8 is a diagram showing a result of examining a relationship between a ratio Vr / Dy of a reverse bias voltage Vr and an organic layer thickness Dy and a short-circuit rate of upper and lower electrodes.
FIG. 9 is a table showing physical properties of an organic EL panel used in a specific example of the embodiment.
FIG. 10 is a diagram showing the relationship between the thickness of an organic layer and the average breakdown voltage of the organic layer examined by the present inventors.
[Explanation of symbols]
20 lower electrode, 30 organic layer, 33 light emitting layer, 40 upper electrode,
50 pixels.

Claims (22)

In an organic EL panel having a pixel (50) including an organic layer (30) including a light emitting layer (33) between a lower electrode (20) and an upper electrode (40),
An organic EL panel, wherein the pixel is capable of self-repair when a reverse bias voltage equal to or lower than the withstand voltage of the organic layer is applied under a voltage application condition during use. The organic EL panel according to claim 1, wherein the withstand voltage of the organic layer (30) is a withstand voltage when driven for 1 minute or less under a voltage application condition during use. The organic EL panel according to claim 1, wherein the reverse bias voltage is equal to or less than の of a withstand voltage of the organic layer. 4. The method according to claim 1, wherein the withstand voltage of the organic layer is expressed as electric field intensity per unit thickness of the organic layer, and the electric field intensity is 3 × 10 ⁶ V / cm or more. The organic EL panel according to any one of the above. When the withstand voltage of the organic layer (30) is represented by the electric field strength per unit thickness of the organic layer, when calculating the electric field strength, the conductive organic film is excluded from the organic layer, and the electric field strength is The organic EL panel according to claim 1, wherein the organic EL panel has a voltage of 3.4 × 10 ⁶ V / cm or more. When the reverse bias voltage is Vr, the thickness of the upper electrode (40) is Da, and the ratio Vr / Da between Vr and Da is Xa, Xa is 2.2 × 10 ⁶ V / cm or more. The organic EL panel according to claim 1, wherein: The thickness Da of the upper electrode (40) is reduced to 100 nm or less, thereby ensuring that the Xa is 2.2 × 10 ⁶ V / cm or more. The organic EL panel according to 1. Assuming that the reverse bias voltage is Vr, the thickness of the organic layer (30) is Dy, and the ratio Vr / Dy of Vr to Dy is Ya, the Ya is 1.2 × 10 ⁶ V / cm or more. The organic EL panel according to claim 1, wherein the organic EL panel has a voltage of 2.2 × 10 ⁶ V / cm or less. When the reverse bias voltage is Vr, the thickness of the organic layer (30) excluding the conductive organic film is Dy ′, and the ratio Vr / Dy ′ between Vr and Dy ′ is Ya ′, 8. The organic EL panel according to claim 1, wherein Ya ′ is 1.4 × 10 ⁶ V / cm or more and 2.4 × 10 ⁶ V / cm or less. 9. The organic EL panel according to any one of claims 1 to 9, wherein the pixels (50) are sealed with a gas containing 0.5% or more of a supporting gas. The organic EL panel according to any one of claims 1 to 10, wherein the lower electrode (20) has an average surface roughness Ra of 2 nm or less. In a method for repairing an organic EL panel having a pixel (50) including an organic layer (30) including a light emitting layer (33) between a lower electrode (20) and an upper electrode (40),
A method for repairing an organic EL panel, wherein the pixel is self-repaired by applying a reverse bias voltage equal to or lower than the withstand voltage of the organic layer under voltage application conditions during use. The method for repairing an organic EL panel according to claim 12, wherein the withstand voltage of the organic layer (30) when driven for 1 minute or less under a voltage application condition during use is used. 14. The method according to claim 12, wherein a voltage that is equal to or less than half of a withstand voltage of the organic layer is used as the reverse bias voltage. 15. When the withstand voltage of the organic layer (30) is represented by the electric field strength per unit thickness of the organic layer, an organic EL panel having an electric field strength of 3 × 10 ⁶ V / cm or more is used. Item 15. The method for repairing an organic EL panel according to any one of Items 12 to 14. When the withstand voltage of the organic layer (30) is represented by the electric field strength per unit thickness of the organic layer, when calculating the electric field strength, the conductive organic film is excluded from the organic layer, and the electric field strength is The method for repairing an organic EL panel according to claim 12, wherein an organic EL panel having a voltage of 3.4 × 10 ⁶ V / cm or more is used. When the reverse bias voltage is Vr, the thickness of the upper electrode (40) is Da, and the ratio Va / Da between Vr and Da is Xa, Xa is 2.2 × 10 ⁶ V / cm or more. The method for repairing an organic EL panel according to any one of claims 12 to 16, wherein: 18. The method according to claim 17, wherein the thickness Da of the upper electrode (40) is reduced to 100 nm or less to ensure that Xa is 2.2 × 10 ⁶ V / cm or more. The method for repairing an organic EL panel described in the above. When the reverse bias voltage is Vr, the thickness of the organic layer (30) is Dy, and the ratio Va / Dy between Vr and Dy is Ya, the Ya is 1.2 × 10 ⁶ V / cm or more. The method for repairing an organic EL panel according to any one of claims 12 to 18, wherein the pressure is set to 2.2 x 10 ⁶ V / cm or less. When the reverse bias voltage is Vr, the thickness of the organic layer (30) excluding the conductive organic film is Dy ′, and the ratio Vr / Dy ′ between Vr and Dy ′ is Ya ′, 19. The method for repairing an organic EL panel according to claim 12, wherein Ya 'is not less than 1.4 × 10 ⁶ V / cm and not more than 2.4 × 10 ⁶ V / cm. 21. The self-repairing method according to claim 12, wherein the self-repair is performed in a state where the pixel is sealed with a gas containing 0.5% or more of a supporting gas. For repairing organic EL panels. 22. The method according to claim 12, wherein the lower electrode has an average surface roughness Ra of 2 nm or less.

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