JP2004139746A - Method for manufacturing organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide an organic EL (electroluminescence) element having a long luminance lifetime. <P>SOLUTION: A method for manufacturing the organic EL element includes a step of sequentially forming a lower electrode layer made of an ITO (indium tin oxide), an organic layer containing an organic EL material and an upper electrode layer on a substrate. In this method, a surface treatment of the lower electrode layer is performed to set a carbonyl compound existing on a surface of the ITO, to a specified amount or less at a surface state of the ITO immediately before the organic layer is formed. It means to set the carbonyl compound to the specific amount or less that in a spectrum of the surface of the ITO obtained by an XPS (X-ray photoelectron spectroscopy) analyzing method, a ratio (P2/P1) of an oxygen peak P1 originating from an In<SB>2</SB>O<SB>3</SB>present at 530 eV and the peak P2 originated from C=O present at 532 eV becomes 0.43 or less, where the peaks P1, P2 are among the peaks P1, P2 and P3 obtained by waveform separating a peak P0 originating from O1s by a curve fitting method. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic EL device in which a lower electrode layer made of ITO (indium tin oxide), an organic layer made of an organic EL material, and an upper electrode layer are sequentially formed on a substrate, and a method of manufacturing the same. The present invention relates to a method for surface treatment of a layer.
[0002]
[Prior art]
In general, an organic EL (electroluminescence) element has excellent visibility due to self-emission and can be driven at a low voltage of several V to several tens of V, so that the weight including a driving circuit can be reduced. Therefore, it can be expected to be used as a thin film display, lighting, and backlight. Further, the organic EL element is characterized by abundant color variations.
[0003]
In such an organic EL device, a lower electrode layer made of ITO (indium tin oxide) is formed on a substrate such as glass, and then the lower electrode layer is subjected to a surface treatment. One or more organic layers made of an organic EL material are formed by an evaporation method or the like, and an upper electrode layer is formed on the organic layer.
[0004]
Here, the surface treatment is performed on the lower electrode layer on the substrate before forming the organic layer. The purpose of this is to largely clean the electrode surface and improve the physical properties of the electrode surface. The work function is adjusted so that charges are easily injected into the layer.
[0005]
As a surface treatment of such a lower electrode layer, conventionally, a treatment of irradiating ultraviolet rays at room temperature while introducing ozone as necessary (hereinafter referred to as UV treatment) has been used (for example, see Patent Document 1). A method of exposing the electrode surface to plasma such as oxygen plasma (hereinafter referred to as plasma processing) is used.
[0006]
The plasma treatment is a very advantageous method as a process because the treatment is performed in a vacuum and can be directly used for forming an organic layer through the vacuum. However, since the physical energy of the plasma particles is very high, depending on the processing conditions, if the surface composition of the ITO is changed or excessive, the ITO itself is etched and the unevenness of the electrode surface is deteriorated. Occasionally, it is difficult to handle.
[0007]
On the other hand, UV treatment is a technique that can be applied relatively easily because it has little effect on ITO itself. In this UV treatment, contaminants such as organic substances existing on the surface of the lower electrode layer are decomposed by UV irradiation, and decomposition products generated thereby are removed by reacting with ozone and gasifying, thereby cleaning the surface. You.
[0008]
[Patent Document 1]
JP-A-10-261484
[0009]
[Problems to be solved by the invention]
However, the present inventors have found that in the UV treatment and the plasma treatment, the luminance life of the organic EL element may be insufficient depending on the treatment conditions.
[0010]
In the related art, when surface treatment is performed on the lower electrode layer, the relationship between the luminance life of the organic EL element and the processing conditions has not been clarified, and it has been difficult to reliably manufacture an organic EL element that can ensure the luminance life. Was.
[0011]
In view of the above problems, it is an object of the present invention to stably provide an organic EL device having a long luminance life.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the surface treatment of the lower electrode layer, the inventors focused on the state of the electrode surface after the surface treatment and made intensive studies.
[0013]
Contaminants existing in the air and the like adhere to the lower electrode layer before the surface treatment, but as a result of the investigation, it was found that, in the conventional surface treatment method, the carbonyl compound remained among them and greatly affected the luminance life. Was.
[0014]
This carbonyl compound cannot be sufficiently removed from the ITO surface constituting the lower electrode layer by the conventional UV treatment, and remains. The carbonyl compound has a C ＝ O bond, and the binding energy of this C ＝ O bond (about 190 kcal / mol) is higher than the binding energy of other organic compounds. Particularly, in the case of UV treatment, a commonly used UV wavelength is used. This is because cutting cannot be performed with an energy of, for example, 185 nm (about 154 kcal / mol).
[0015]
In this carbonyl compound, since the CＯO bond has a small energy gap, the energy of light emission used in the organic EL element is transferred to the C ＝ O bond portion and released, and as a result, It is considered that energy for light emission is wastefully consumed, leading to a reduction in luminance life.
[0016]
However, the present inventors have found that the carbonyl compound existing on the ITO surface can be sufficiently removed by changing the conditions of the surface treatment as compared with the related art. That is, it has been found that a sufficient luminance life can be secured if the amount of the carbonyl compound remaining on the ITO surface after the surface treatment is equal to or less than a specified amount. The present invention has been created based on the results of such studies.
[0017]
That is, according to the first aspect of the present invention, after a lower electrode layer (20) made of ITO (indium tin oxide) is formed on a substrate (10), a surface treatment of the lower electrode layer is performed. In a method of manufacturing an organic EL device, one or more organic layers (30) made of an organic EL material are formed on a lower electrode layer, and an upper electrode layer (40) is formed on the organic layer. In the surface treatment step of the electrode layer, the surface state of the lower electrode layer immediately before forming the organic layer is subjected to a surface treatment so that the carbonyl compound present on the ITO surface constituting the lower electrode layer is not more than a specified amount. is there.
[0018]
Here, when the carbonyl compound is reduced to the specified amount or less, the peaks (P1, P2, and P2) obtained by separating the peak (P0) derived from O1s from the waveform by the curve fitting method in the spectrum obtained by the XPS analysis method on the ITO surface. In P3), In which appears at 530 eV ₂ O ₃ The carbonyl / oxygen peak ratio (P2 / P1), which is the ratio of the oxygen peak (P1) derived from C ＝ O and the peak (P2) appearing at 532 eV, is 0.43 or less.
[0019]
According to the study of the present inventors, in order to make the luminance life of the organic EL element sufficiently long, the carbonyl / oxygen peak ratio is reduced to 0.43 or less when the lower electrode layer is subjected to surface treatment. Experimentally, it was found that reducing the carbonyl compound was sufficient (see FIG. 18).
[0020]
Therefore, according to the present manufacturing method, an organic EL device having a long luminance life can be stably provided.
[0021]
Furthermore, as a result of further study, when the carbonyl compound remaining on the ITO surface is reduced to a specified amount or less in the surface treatment of the lower electrode layer, the change in the composition state of the ITO is further limited to a predetermined amount or less. It has been found that the use of appropriate processing conditions can more reliably improve the luminance life.
[0022]
That is, in the invention according to claim 2, in the manufacturing method according to claim 1, the surface treatment step of the lower electrode layer (20) is such that the composition ratio of oxygen and indium of ITO constituting the lower electrode layer is changed before and after the surface treatment. The surface treatment is performed so as to keep the change within a predetermined amount.
[0023]
Here, the term “change within a predetermined amount” refers to a peak obtained by separating the peak (P0) derived from O1s from the waveform obtained by the XPS analysis method on the ITO surface by the curve fitting method, and is 530 eV. Appearing In ₂ O ₃ The value after the surface treatment in the oxygen / indium peak ratio, which is the ratio of the oxygen peak (P1) derived from the semiconductor and the peak derived from In at 444 eV in the same spectrum is 90% or more of the value before the surface treatment. It is.
[0024]
According to the study of the present inventors, the change in the ITO composition ratio before and after the surface treatment was adjusted so that the value of the oxygen / indium peak ratio after the surface treatment was 90% or more of the value before the surface treatment. It was experimentally found that the smaller the size, the more reliably the luminance life of the organic EL element can be made long (see FIG. 19).
[0025]
Here, specifically, the surface treatment of the lower electrode layer (20) in the manufacturing method according to the first or second aspect is specifically performed on the substrate (10) as in the third aspect of the invention. It can be appropriately realized by performing a treatment by irradiating ultraviolet rays while heating the substrate so that the temperature becomes 145 ° C. or higher.
[0026]
The present invention has been found experimentally as a result of examination. By performing UV treatment at 145 ° C. or higher, a carbonyl compound which was difficult to decompose by conventional UV treatment at normal temperature is decomposed. Can be removed.
[0027]
In particular, in realizing the manufacturing method of the second aspect, it is possible to realize the manufacturing method of the second aspect by adjusting the processing conditions even in the plasma processing, but in the present invention, the manufacturing method of the second aspect is more easily realized than the plasma processing. Can be preferred.
[0028]
According to a fourth aspect of the present invention, in the method of manufacturing an organic EL device according to the third aspect, the surface treatment of the lower electrode layer (20) is performed in advance in the inside of the treatment tank before performing the treatment by ultraviolet irradiation. Ozone is introduced and filled.
[0029]
According to this, when UV treatment is performed in the surface treatment of the lower electrode layer, the treatment atmosphere becomes a state in which ozone is sufficiently present, so that decomposition products generated in the UV treatment are more reliably gasified. Is preferred.
[0030]
According to a fifth aspect of the present invention, in the method for manufacturing an organic EL device according to the third or fourth aspect, as a surface treatment of the lower electrode layer (20), a treatment by ultraviolet irradiation is performed, and then a treatment by plasma is performed. Is performed.
[0031]
According to this, after performing UV treatment in the surface treatment of the lower electrode layer, a trace amount of decomposition products can be surely removed by plasma treatment, which is preferable.
[0032]
The preferable method described in the manufacturing method of claim 4 or claim 5 is, in particular, as described in claim 6, in the surface treatment step of the lower electrode layer (20), the lower electrode layer (20) is used as the substrate (10). In addition, the present invention is preferably applied to a case where members (60, 70) made of an organic substance are formed on a substrate.
[0033]
When UV treatment is performed on a substrate on which a member such as a partition and a film made of an organic material is formed in addition to the lower electrode layer to be subjected to the surface treatment, the organic material of the partition or the film remains as a decomposition product and remains after the treatment, There is a possibility that device characteristics may be adversely affected. In this regard, it is effective if the above-described method capable of reliably removing the decomposition product is employed.
[0034]
In addition, the invention according to claim 7 is that, on the substrate (10), a lower electrode layer (20) made of indium tin oxide, one or more organic layers (30) made of an organic EL material, and an upper electrode layer (20). 40), in the spectrum obtained by analyzing the surface state of the lower electrode layer before the organic layer is formed by the XPS analysis method as the lower electrode layer in the organic EL element formed sequentially, the peak derived from O1s. Of the peaks (P1, P2, P3) obtained by separating the waveform of (P0) by the curve fitting method, In which appears at 530 eV ₂ O ₃ The peak having a carbonyl / oxygen peak ratio (P2 / P1) of 0.43 or less, which is the ratio of the oxygen peak (P1) derived from C = O and the peak (P2) derived from C = O appearing at 532 eV, is used. It is characterized by the following.
[0035]
The present invention can be appropriately manufactured by the manufacturing method according to the first aspect, and its effects are the same as those of the first aspect.
[0036]
Here, as in the invention according to claim 8, a member (60, 70) made of an organic substance can be formed on the substrate (10) in addition to the organic layer (30). This is the same as the sixth aspect of the present invention.
[0037]
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.
[0038]
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 cross-sectional configuration of an organic EL (electroluminescence) element S1 according to an embodiment of the present invention.
[0039]
The organic EL element S1 includes a substrate 10 made of a transparent glass substrate or a resin substrate. On this substrate 10, an anode 20 made of ITO (indium tin oxide) as a lower electrode layer, and an organic EL material The organic layer 30 including the light emitting layer 33 and the cathode 40 as an upper electrode layer are sequentially laminated.
[0040]
Here, the stacked body 50 in which the anode 10 to the cathode 40 are stacked is divided into a plurality by an electrically insulating insulating film 60, and a partition wall higher than the stacked body 50 is provided on the insulating film 60. 70 are formed. As a result, each stacked body 50 divided by the insulating film 60 and the partition 70 is configured as a pixel.
[0041]
Next, the material and the like of each of the layers and the like formed on the substrate 10 will be described. As described above, the anode 20 is a transparent electrode film made of ITO (oxide of indium and tin) or the like. The anode 20 is formed by patterning an ITO film formed to a thickness of about 150 nm by a sputtering method or the like by a normal photolithography method.
[0042]
The organic layer 30 includes, in order from the anode 20 side, a hole injection layer 31 made of a hole injection organic material, a hole transport layer 32 made of a hole transport organic material, a light emitting layer 33 made of an organic EL material, and electron transport. An electron transport layer 34 made of a conductive organic material is laminated by a vapor deposition method or the like.
[0043]
In this example, the hole injection layer 31 is CuPc (copper phthalocyanine complex) having a thickness of about 10 nm, the hole transporting layer 32 is a triphenylamine tetramer having a thickness of about 40 nm, and the light emitting layer 33 is an electron transporting material. A film obtained by adding dimethylquinacridone to certain Alq and having a thickness of about 40 nm, and the electron transport layer 34 is made of Alq having a thickness of about 20 nm.
[0044]
Further, the cathode 40 is formed by evaporating a metal material or the like. In this example, a LiF film 41 having a thickness of about 0.5 nm as an electron injection layer and an Al film 42 having a thickness of about 150 nm are sequentially formed from the organic layer 30 side. It is formed of a film by a vapor deposition method or the like.
[0045]
The members 60 and 70 made of organic substances other than the organic layer 30 formed on the substrate 10, that is, the insulating film 60 is made of a resin material such as photosensitive polyimide, while the partition wall 70 is made of a negative photosensitive resin resist material or the like. Become.
[0046]
Although not shown, the organic EL element S1 is provided with a sealing can made of stainless steel or the like on the substrate 10, and covers and protects each part on the substrate 10 with the sealing can.
[0047]
In such an organic EL element S1, light emission is performed at a desired pixel, that is, the stacked body 50. Specifically, electrons and holes are injected into the light emitting layer 33 by applying a voltage between the anode 20 and the cathode 40, and the light emitting layer 33 emits light by the energy generated by the combination of these electrons and holes. I do. This light emission is extracted from, for example, the substrate 10 side.
[0048]
[Method of Manufacturing Organic EL Element S1]
Next, a method for manufacturing the above-described organic EL element S1 will be described. First, an anode 20 made of ITO is formed at a predetermined position on the substrate 10 (anode forming step). In this example, the anode 20 is formed by depositing ITO to a thickness of about 150 nm by a sputtering method or the like and patterning the film by a normal photolithography method.
[0049]
Next, the insulating film 60 is formed of a resin such as photosensitive polyimide on the substrate 10 in a portion between the stacked bodies (pixels) 50 (insulating film forming step). Further, a partition 70 for separating the organic layer 30 and the cathode 40 is formed by photolithography on the insulating film 60 (partition forming step).
[0050]
After the anode (lower electrode layer) 20, the partition wall 70 made of an organic material, and the insulating film 60 as a film made of an organic material are formed in this way, the surface treatment of the anode 20 is performed before the organic layer 30 is formed (the anode). Surface treatment step).
[0051]
The surface treatment of the anode 20 is performed by changing the surface state of the anode 20 immediately before the formation of the organic layer 30 to the carbonyl existing on the ITO surface constituting the anode 20 in order to make the luminance life of the organic EL element sufficiently long. The reaction is performed so that the amount of the compound is not more than the specified amount.
[0052]
Specifically, when the carbonyl compound content is reduced to a specified amount or less, a peak derived from O1s in a spectrum obtained by an analysis method using XPS (X-ray photoelectron spectroscopy) on the ITO surface is used. Then, processing conditions are determined such that the carbonyl compound is not more than a specified amount in the spectrum of the ITO surface after the surface processing, and the surface processing is performed based on the obtained processing conditions.
[0053]
This spectrum is obtained as follows. The glass substrate 10 on which the anode 20 made of ITO is formed is subjected to a surface treatment and then transferred to a glove box. In a glove box, it is loaded into a transfer sealing jig (hereinafter referred to as a vessel) attached to the XPS and transferred to the analyzer. Since the vessel is directly connected to the analyzer, it can be inserted into the analyzer without being exposed to the atmosphere. Then, the analysis is performed.
[0054]
FIG. 2 is a diagram showing an example of a peak derived from O1s in a spectrum obtained by the XPS analysis. In FIG. 2, what is indicated by a broken line P0 is a peak derived from O1s in the actually measured spectrum.
[0055]
This O1s peak P0 has a shape like a superposition of a plurality of peaks, because oxygen of some compounds is present. This peak P0 can be separated into waveforms by a curve fitting method.
[0056]
In this case, as shown in FIG. 2, calculation was performed by the curve fitting method so as to match the peak P0 of O1s, and the peak was separated into three peaks P1, P2, and P3. The sum of the peaks P1 to P3 obtained separately is shown as a peak P0 ′, and this peak P0 ′ is in good agreement with the actually measured peak P0.
[0057]
It is theoretically known from which compound the oxygen of each of the separated peaks P1, P2, and P3 is derived from, and the peak P1 corresponds to ITO (In ₂ O ₃ ), The peak P2 is a peak derived from C ＝ O (carbonyl group) of the contaminant remaining after the treatment, and the peak P3 is a peak derived from C—O of the contaminant.
[0058]
Here, the peak P2 derived from C = O can be confirmed by waveform separation of the peak of C1s as well as the peak of O1s. By utilizing this fact, it was confirmed that the separated peak P2 in the O1s peak P0 really originated from C ＝ O.
[0059]
Some ITO surfaces were measured, and the peak intensity of the peak P2 (C = O in O1s) at O1s and the peak intensity of C = O-derived peak (C = O in C1s) obtained from waveform separation of the C1s peak were measured. The correlation was confirmed. The result is shown in FIG. As shown in FIG. 3, the peak intensities of both peaks are well correlated, and from this result, it was confirmed that the peak P2 of O1s was derived from C ＝ O.
[0060]
As the definition of the residual amount of the carbonyl compound in the present embodiment, the intensity of the peak P1 derived from ITO does not change even if the surface treatment conditions of the anode are changed. The ratio (P2 / P1) between the peak P1 appearing at 530 eV and the peak P2 appearing at 532 eV was used.
[0061]
In the surface treatment of the anode 20 in the present embodiment, as a surface state of the anode 20 immediately before the formation of the organic layer 30, a peak P0 derived from O1s in a spectrum obtained by the XPS analysis method on the ITO surface is formed by a curve fitting method. In which appears at 530 eV among peaks P1 to P3 obtained by waveform separation ₂ O ₃ The treatment is performed under such surface treatment conditions that the ratio (P2 / P1) of the oxygen peak P1 derived from C = O and the peak P2 derived from C = O appearing at 532 eV becomes 0.43 or less. This peak ratio is hereinafter referred to as carbonyl / oxygen peak ratio (P2 / P1).
[0062]
Although the details will be described later, if the surface treatment of the anode 20 is performed so that the carbonyl / oxygen peak ratio (P2 / P1) is 0.43, the carbonyl compound present on the ITO surface can be sufficiently reduced, The fact that the luminance life of the organic EL element can be made sufficiently long has been experimentally found by the study of the present inventors.
[0063]
Further, as the surface treatment of the anode 20, in order to more surely make the luminance life of the organic EL element sufficiently long, a treatment condition is adopted such that the change in the composition state of ITO is kept within a predetermined amount. Is preferred. Although it is preferable that the change in the ITO composition is small, the present inventors have found that if the degree of the change is within a predetermined amount, it is highly effective in securing the luminance life.
[0064]
That is, in the surface treatment step of the anode 20, the oxygen and the indium of ITO are adjusted while keeping the carbonyl / oxygen peak ratio (P2 / P1) at 0.43 as the surface state of the anode 20 immediately before forming the organic layer 30. It is preferable to perform the surface treatment so that the composition ratio of the above remains within a predetermined amount before and after the surface treatment.
[0065]
Specifically, staying within a change within a predetermined amount means that in a spectrum obtained by XPS analysis on the ITO surface, the peak P0 derived from O1s appears at 530 eV obtained by separating the waveform by a curve fitting method. ₂ O ₃ The value after the surface treatment in the oxygen / indium peak ratio, which is the ratio between the oxygen peak P1 originating from P1 (see FIG. 2) and the peak derived from In (not shown) at 444 eV, is 90% of the value before the surface treatment. That is all.
[0066]
Although the details will be described later, if the change in the ITO composition ratio before and after the surface treatment is reduced so that the value of the oxygen / indium peak ratio after the surface treatment is 90% or more of the value before the surface treatment, it is more preferable. It has been experimentally found by the present inventors that the luminance life of the organic EL element can be made sufficiently long.
[0067]
The above-described surface treatment in consideration of the carbonyl / oxygen peak ratio (P2 / P1) and the oxygen / indium peak ratio is performed by heating the substrate 10 such that the temperature of the substrate 10 (substrate temperature) becomes 145 ° C. or higher. It can be realized by appropriately adjusting the processing conditions by using a treatment by ultraviolet irradiation (UV treatment) or a plasma treatment using an oxygen-argon mixed gas or the like.
[0068]
For example, as the UV processing conditions, UV irradiation can be performed at an ozone flow rate of 0.5 to 10 liters / minute for about 3 to 20 minutes with the actual substrate temperature kept at 145 ° C. or higher. As the plasma processing conditions, an oxygen gas and an argon gas are introduced at a ratio of 1: 9 so that the pressure becomes 1.0 Pa, and the RF power is set to 50 W and the processing is performed for 200 seconds.
[0069]
Further, in the case of performing UV treatment at a substrate temperature of 145 ° C. or higher as the surface treatment of the anode 20 of the present embodiment, a more preferable embodiment will be described below. One is to inject ozone into the UV processing tank and fill it beforehand before performing the ultraviolet irradiation.
[0070]
If ozone is preliminarily introduced in this way, when UV treatment is performed in the surface treatment of the anode 20, the treatment atmosphere becomes sufficient for ozone, so that decomposition products generated in the UV treatment are reduced. It is preferable because it can be surely gasified. When the substrate becomes large and the processing tank becomes large and ozone tends to be insufficient, the above decomposition products tend to remain. However, this method can avoid such a problem.
[0071]
The second one is to perform processing by plasma after performing processing by ultraviolet irradiation, that is, to perform plasma assist. According to this, after performing the UV treatment, a small amount of decomposition products remaining on the ITO surface of the anode 20 can be reliably removed by the plasma treatment, which is preferable.
[0072]
As the conditions of such auxiliary plasma processing, for example, oxygen gas and argon gas are introduced at a ratio of 1: 9 so that the pressure becomes 1.0 Pa, the RF power is set to 30 W, and the processing is performed for several tens of seconds. You can do it.
[0073]
Further, these two preferred embodiments are the same as the organic EL element of the present embodiment, except that in the anode surface treatment step, a member made of an organic substance (that is, the insulating film 60 and the partition wall 70 in this example) is used as the substrate 10 as the substrate 10. It is suitable when using what was formed on 10.
[0074]
When the substrate 10 on which a member made of an organic substance is formed other than the anode 20 to be subjected to the surface treatment is subjected to UV treatment, these organic substances become decomposition products, remain after the treatment, and may adversely affect device characteristics. . In this regard, it is effective if the above-described method capable of reliably removing the decomposition product is employed.
[0075]
After performing the anode surface treatment step in this manner, the organic layer 30 is formed and laminated on the anode 20 by using a vapor deposition method or the like (organic layer forming step), and the cathode is formed on the organic layer 30. The layered body 50 is formed by forming and stacking the layers 40 (cathode film forming step). The film formation example of the organic layer 30 and the cathode 40 in this example is as described above.
[0076]
Although not shown, in practice, a film similar to the organic layer 30 and the cathode 40 is also stacked on the upper end surface of the partition 70 by such a film forming method. Thereafter, by performing a process such as attaching the sealing can, the organic EL element S1 is completed.
[0077]
In the organic EL element S1 completed in this way, particularly as the anode 20 made of ITO, in the spectrum obtained by analyzing the surface state of the anode 20 before forming the organic layer 30 by the XPS analysis method, O1s Of the peak P0 originating from the peak P0 obtained at 530 eV out of the peaks P1 to P3 obtained by separating the waveform by the curve fitting method. ₂ O ₃ The carbonyl / oxygen peak ratio (P2 / P1), which is the ratio of the peak P2 derived from C ＝ O appearing at 532 eV to the peak P1 derived from 532 eV, is 0.43 or less. .
[0078]
As described above, according to the manufacturing method of the present embodiment, by performing the surface treatment of the anode 20 in consideration of the carbonyl / oxygen peak ratio (P2 / P1) or the oxygen / indium peak ratio, a long luminance life can be achieved. The organic EL device can be provided stably.
[0079]
Next, in the above-described manufacturing method of the present embodiment, the grounds for adopting the surface treatment in consideration of the carbonyl / oxygen peak ratio (P2 / P1) and the oxygen / indium peak ratio, and the grounds for adopting a more preferable form, etc. State. The grounds for adoption are based on the following studies by the present inventors.
[0080]
[Examination of UV irradiation 1]
The conventional UV treatment is performed at room temperature, and energy due to UV irradiation cannot provide sufficient energy to break the CＯO bond. Therefore, it was studied to increase the energy applied to the C 付 与 O bond by heating the substrate.
[0081]
As shown in FIG. 4, a sample as a substrate with ITO was formed on a glass substrate 10 up to an anode 20 made of ITO.
[0082]
Then, using this sample, no UV treatment was performed (no UV treatment), Study Example 1 was a UV treatment at ordinary temperature as in the past (UV (normal temperature) treatment), and Study Example 2 was UV-treated at a set temperature of 100 ° C. (UV (100 ° C.) treatment), and as Study Example 3, UV-treated at a set temperature of 150 ° C. of the processing apparatus (UV (150 ° C.) treatment) were produced.
[0083]
Here, the UV treatment was performed for 20 minutes at an ozone flow rate of 0.5 L / min at the above-mentioned set temperatures of normal temperature, 100 ° C., and 150 ° C. using a UV ozone treatment apparatus for a 100 mm square substrate. Then, XPS analysis was performed on the ITO surface of each of the samples of Study Examples 1 to 3 to which no UV treatment and each temperature were applied.
[0084]
This XPS analysis was performed as described above, and the carbonyl / oxygen peak ratio (P2 / P1) was determined for each of the treated samples. The result is shown in FIG. From FIG. 5, it can be seen that heating the substrate 10 reduces the peak ratio (P2 / P1) and enhances the effect of removing the carbonyl compound.
[0085]
Here, the set temperature of the processing apparatus, that is, the processing temperature is slightly different from the actual temperature of the substrate 10, that is, the substrate temperature. This is because the substrate temperature becomes higher than the processing temperature due to the radiant heat of the UV lamp. In FIG. 5, when the processing temperature is room temperature, 100 ° C., and 150 ° C., the substrate temperature is 60 ° C., 115 ° C., and 170 ° C., respectively.
[0086]
Then, in examining the relationship between the substrate temperature and the luminance life, the samples of the examination examples 1 to 3 that were subjected to the above-mentioned UV (normal temperature) treatment, UV (100 ° C.) treatment, and UV (150 ° C.) treatment were The organic layer 30 and the cathode 40 were formed on the anode 20 in the same manner as in the above-described example, and an organic EL element was formed by assembling a sealing can (not shown).
[0087]
FIG. 6 shows a sectional configuration thereof. In this organic EL element, there is no member made of an organic material other than the organic layer such as a partition and an insulating film.
[0088]
Again, in the organic EL device shown in FIG. 6, the organic layer 30 has a hole injection layer 31 made of CuPc with a thickness of 10 nm, and a hole transport layer 32 made of a triphenylamine tetramer with a thickness of 40 nm. A light-emitting layer 33 formed by adding dimethylquinacridone to Alq and having a thickness of 40 nm, and an electron transport layer 34 of Alq having a thickness of 20 nm are sequentially laminated. The cathode 40 is formed by sequentially forming a 0.5 nm thick LiF film 41 and a 150 nm thick Al film 42 as an electron injection layer by an evaporation method or the like.
[0089]
Further, in examining the relationship between the substrate temperature and the luminance lifetime, an organic EL device similar to that shown in FIG. 6 was manufactured using a substrate with ITO similarly subjected to UV treatment at a processing temperature of 200 ° C. (substrate temperature: 230 ° C.). This element was designated as Study Example 4.
[0090]
The luminance life of the organic EL devices of Study Examples 1 to 4 obtained at each substrate temperature was examined. Brightness life is 2400 cd / m2 initial brightness at 85 ° C ² , The time during which the luminance when the DC drive was performed was halved, that is, the luminance half life was used. That is, the luminance half life is such that the luminance is 1200 cd / m at 85 ° C. ² Driving time.
[0091]
FIG. 7 shows the relationship between the substrate temperature (° C.) and the luminance half life (hr). The half life of luminance was 60 hours in Study example 1, 75 hours in Study example 2, 95 hours in Study example 3, and 98 hours in Study example 4. By the way, the time without UV treatment was about 20 hours. From this result, it was clarified that the luminance half life was sufficiently improved when the substrate temperature was at least about 170 ° C. or higher.
[0092]
In addition, the carbonyl / oxygen peak ratio (P2 / P1) determined for the samples (Examination Examples 1 to 3) having no UV treatment and treatment temperatures of normal temperature, 100 ° C., and 150 ° C. in the above-described study, and prepared using the samples The relationship with the luminance half life obtained for the obtained organic EL device was examined. FIG. 8 shows the result.
[0093]
From the result of FIG. 8, it is sufficient that the carbonyl compound exists on the surface of the anode 20 immediately before the formation of the organic layer 30 as long as the carbonyl / oxygen peak ratio (P2 / P1) is about 0.33 or less. It can be said that the luminance half-life may be reduced by setting the carbonyl / oxygen peak ratio (P2 / P1) to 0.33 or less.
[0094]
As described above, the UV irradiation study 1 has been performed using the test piece in which only the anode 20 (ITO) is formed on the glass substrate 10 and the organic EL element in which the organic layer 30 and the cathode 40 are laminated using the test piece. .
[0095]
From this study, it was found that the surface treatment of the anode 20 was performed by performing UV treatment at a substrate temperature of 170 ° C. or higher, and the surface state of the anode after the surface treatment and before the formation of the organic layer was a carbonyl existing on the ITO surface. It has been found that the compound may be reduced so that the carbonyl / oxygen peak ratio (P2 / P1) is about 0.33 or less. That is, the rough surface treatment conditions could be narrowed down.
[0096]
Based on this result, a study was performed to confirm the effects of the above conditions on the substrate as an actual panel configuration, that is, the substrate 10 on which the partition wall 70 made of an organic substance and the insulating film 60 shown in FIG. Next, this study will be described as “Study of UV irradiation 2”.
[0097]
[Examination of UV irradiation 2]
First, as the organic EL element S1 shown in FIG. 1, an element subjected to UV (150 ° C.) treatment was produced as Study Example 5. Incidentally, the UV (150 ° C.) treatment in the study example 5 was performed in the same manner as the study example 3 in the study 1 of the UV irradiation.
[0098]
That is, while the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 are formed is heated at a processing temperature of 150 ° C. (substrate temperature is 170 ° C.), an ozone flow rate of 0.5 The surface treatment was performed at liter / minute for 20 minutes. Then, similarly, the organic layer 30, the cathode 40, and the sealing can were assembled in the same manner to produce an organic EL device of Study Example 5.
[0099]
With respect to the organic EL device S1 of this study example 5, a standing test at 120 ° C. for 2 hours was performed. FIG. 9 is a diagram showing the results of examining the voltage-current characteristics as element characteristics before and after this standing test. As can be seen from FIG. 9, the current-voltage characteristics were significantly reduced after being left as compared to the initial stage. For example, the current density at a voltage of 8 V was about 14% of that before leaving.
[0100]
When the light emitting state of the organic EL element S1 of the study example 5 in which the characteristics were thus reduced was confirmed, it was found that luminance unevenness and luminance reduction occurred around the partition wall 70 and the insulating film (flattening film) 60. . From this, it was determined that the charge was hardly injected around the partition 70 and the insulating film 60.
[0101]
The reason for this is that organic substances such as the partition wall 70 and the insulating film 60 are decomposed by ultraviolet rays and are not gasified due to insufficient oxidation reaction between the decomposition product and ozone, and the ITO surface around the partition wall 70 and the insulating film 60 It is conceivable that it adhered to the surface. Then, it was presumed that the adhesion caused a change in the surface state of the ITO (anode), thereby deteriorating the film quality and adhesion of the organic layer 30 formed thereon.
[0102]
Two verification experiments were performed to verify the estimation model. The first is to reduce the processing time of the UV processing. Reducing this processing time should reduce the amount of decomposition products that accumulate. The second is to increase the ozone concentration. Increasing the ozone concentration should increase the probability of oxidation reaction and reduce the amount of decomposition products.
[0103]
“Verification of shortening of processing time”: First, verification of reduction of processing time was performed. Here, the processing conditions of the UV (150 ° C.) processing in Study Example 5 above, that is, the processing conditions of an ozone flow rate of 0.5 liter / minute and 20 minutes were used as a reference.
[0104]
Then, a surface treatment was performed with the ozone flow rate and the treatment time changed under the reference treatment conditions, and thereafter, the organic EL element S1 shown in FIG. 1 was manufactured in the same procedure.
[0105]
Specifically, as an investigation example 6, an ozone flow rate of 0.5 liter / min for 10 minutes, as an investigation example 7, an ozone flow rate of 1.0 liter / min for 10 minutes, and as an investigation example 8, an ozone flow rate of 0 liter / min. 0.5 l / min for 5 minutes, Study Example 9 for an ozone flow rate of 1.0 L / min for 5 minutes, and Study Example 10 for an ozone flow rate of 1.0 L / min for 3 minutes Produced.
[0106]
The organic EL devices of Examination Examples 5 to 10 were subjected to the same high-temperature storage test at 120 ° C. for 2 hours, and the current density ratio at a voltage of 8 V before and after the storage test was examined. This current density ratio is a ratio after the standing at a voltage of 8 V before the standing, and the larger the current density ratio, the smaller the change in characteristics and the better. That is, it is an index of the change in the voltage-current characteristics.
[0107]
As a result of examining the current density ratio, as described above, the current density ratio was 14% in Study Example 5, 12% in Study Example 6, 41% in Study Example 7, 63% in Study Example 8, 73% in Study Example 9, and In Study Example 10, the ratio was 100%. FIG. 10 is a graph of the result.
[0108]
From the results shown in FIG. 10, it can be seen that the shorter the processing time, the larger the current density ratio, that is, the smaller the change in element characteristics. Therefore, from these results, it was confirmed that the estimation that the reduction of the processing time was effective was appropriate.
[0109]
In addition, it was feared that the reduction effect of the original carbonyl compound was reduced by shortening the processing time, but since the luminance half life was not changed, the removal effect was sufficient even if the processing time was reduced. it is conceivable that.
[0110]
Incidentally, in the above-described Study Example 10 in which the processing time was shortened to 3 minutes to achieve a current density ratio of 100%, the luminance half life was 97 hours, and the fully improved luminance half life shown in FIGS. The same level of life is ensured.
[0111]
If the processing time is too long, the partition wall 70 and the insulating film 60 are also etched by the UV processing. Therefore, shortening the processing time is also effective in reducing the etching amount. As a result of SEM observation, it was confirmed that when the UV (150 ° C.) treatment was actually performed for 20 minutes, the partition wall 70 and the insulating film 60 were largely etched.
[0112]
"Verification on ozone concentration": Also, from the results shown in FIG. 10, the larger the ozone flow rate, the larger the current density ratio. That is, it was confirmed that the higher the ozone concentration in the UV treatment, the smaller the change in device characteristics even when subjected to high-temperature storage. Verification of this ozone concentration was further advanced.
[0113]
In the present verification 2, the above-mentioned examination examples 5 to 10 were performed using a small-sized 100 mm square substrate UV ozone treatment apparatus. It was considered that the ozone concentration would not be sufficient if the capacity of the processing tank of the apparatus was large, and in order to confirm this, ozone concentration was verified using a large-sized UV ozone treatment apparatus for a 400 mm square substrate. At this time, the processing time was 3 minutes, which is the optimum time in FIG.
[0114]
As a study example 11, while heating the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 were formed at a processing temperature of 150 ° C. (the substrate temperature was 170 ° C.), the ozone flow rate was measured using a UV ozone treatment apparatus for 400 mm square substrate. Surface treatment was performed at 1.0 liter / minute for 3 minutes.
[0115]
Then, similarly, the organic layer 30, the cathode 40, and the sealing can were assembled, and an organic EL device as Study Example 11 was manufactured. The device was subjected to a high-temperature storage test at 120 ° C. for 2 hours, and the current density ratio at a voltage of 8 V before and after the storage was examined.
[0116]
As a study example 12, while heating the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 were formed at a processing temperature of 150 ° C. (the substrate temperature was 170 ° C.), a UV ozone treatment apparatus for a 400 mm □ substrate was used. Surface treatment was performed at an ozone flow rate of 10 liters / minute for 3 minutes.
[0117]
Then, similarly, the organic layer 30, the cathode 40, and the sealing can are assembled to produce an organic EL device as Study Example 12, and the current density at a voltage of 8 V before and after standing as in Study Example 11 When the ratio was examined, it was 12% in Study Example 12. FIG. 11 shows the relationship between the ozone flow rate and the current density ratio in these Study Examples 11 and 12.
[0118]
As described above, the flow rate of ozone was changed in Study Example 11 and Study Example 12, but a decrease in the current density ratio was inevitable. Even in the case of using the same method in a large UV processing apparatus, the same method as in the small UV processing apparatus was used. It turned out that the effect was not reproduced. In particular, although the flow rate of ozone in Study Example 12 was the maximum value of the processing apparatus, the current density ratio decreased.
[0119]
This may be because, in a large-sized UV processing apparatus, since the capacity of the processing tank is large, a longer time is required from the start of processing to the saturation of the ozone concentration as compared with a small-sized UV processing apparatus. Therefore, it is presumed that decomposition products adhere at low concentrations.
[0120]
"Verification of preliminary introduction of ozone" For this reason, before starting the UV treatment, ozone was sufficiently introduced into the treatment tank before starting the treatment, that is, the preliminary introduction of ozone was attempted.
[0121]
As a study example 13, while heating the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 are formed at a processing temperature of 150 ° C. (substrate temperature is 170 ° C.), a UV ozone treatment apparatus for a 400 mm □ substrate is used to remove ozone. After performing the preliminary introduction for 5 minutes, the surface treatment was performed for 3 minutes at an ozone flow rate of 10 L / min.
[0122]
Then, similarly, the organic layer 30, the cathode 40, and the sealing can are assembled in the same manner to produce an organic EL device as Study Example 13, and the current at a voltage of 8 V before and after standing as in Study Example 11 above. When the density ratio was examined, it was 80% in Study Example 13. FIG. 12 shows the result of the study example 13 in comparison with the study example 12 described above.
[0123]
As described above, the current density ratio was significantly improved by the preliminary introduction of ozone, and reached a level comparable to that of a small-sized UV processing apparatus as shown in Study Example 10. From this result, it was confirmed that the oxidation efficiency by ozone was universally important.
[0124]
"Verification of Plasma Assist": Next, in Study 2 of this UV irradiation, the current density ratio could be improved to about 80% when ozone was preliminarily introduced in a large UV processing device. Was further improved to reach 100%.
[0125]
The plasma treatment is an effect due only to plasma particles, and is not a combined effect of UV-induced breaking of molecular bonds and oxidation reaction (gasification) by ozone as in UV treatment. For this reason, it is not necessary to consider much the influence of the decomposition products in the middle stage.
[0126]
However, in the plasma treatment, as described in the section of “Prior Art”, there is a concern that the composition of ITO may be changed or etched, and that the etching of organic substances such as partition walls may be affected. In particular, when the energy of plasma particles is high, , The effect becomes remarkable. However, when the energy of the plasma particles is low, this effect is small.
[0127]
For this reason, in order to remove the decomposition products that may have remained slightly after performing the UV treatment, processing with a very weak plasma for a short time, that is, plasma assist was studied.
[0128]
Here, the definition of the extremely weak plasma is that the magnitude of the pressure or power in the plasma processing is smaller than that at which the plasma processing causes etching or change in the surface morphology of the partition 70 or the insulating film 60. I do.
[0129]
Specifically, as Study Example 14, UV ozone treatment for a 400 mm square substrate is performed while heating the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 are formed at a processing temperature of 150 ° C (substrate temperature is 170 ° C). After preliminarily introducing ozone for 5 minutes by the apparatus, surface treatment was performed for 3 minutes at an ozone flow rate of 10 liters / min. Subsequently, oxygen gas and argon gas were introduced at a ratio of 1: 9, and RF power of 30 W, Plasma treatment was performed for 10 seconds at a pressure of 1.0 Pa.
[0130]
Thereafter, the organic layer 30, the cathode 40, and the sealing can were assembled in the same manner as described above to produce an organic EL device as Study Example 14. The device was subjected to a high-temperature storage test at 120 ° C. for 2 hours, and the current density ratio at a voltage of 8 V before and after storage was 100% in Study Example 14.
[0131]
FIG. 13 shows the result of the study example 14 added to FIG. As described above, it was confirmed that the plasma assist can further improve the current density ratio.
[0132]
The device of this study example 14 was subjected to DC driving in an atmosphere of 85 ° C. to have an initial luminance of 2400 cd / m 2. ² When the luminance life was evaluated, the luminance half life was 99 hr, no adverse effect due to plasma assist was observed, and a sufficiently long life level was secured.
[0133]
As described above, a universal UV treatment method for prolonging the life of the organic EL element could be found from the results of the studies described in “Study of UV irradiation 1” and “Study of UV irradiation 2”. Therefore, an attempt was made to determine whether the same effect could be exhibited by the plasma method.
[0134]
[Study of plasma treatment]
“Study of oxygen plasma”: First, the effect of oxygen plasma, which is a general technique, was confirmed. As a study example 15, using the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 were formed, an oxygen gas was introduced so as to have a pressure of 1.0 Pa as a plasma condition, and RF power was set to 50 W and 200 Plasma treatment was performed for seconds. Incidentally, the plasma conditions are determined as conditions under which organic substances such as the insulating film 60 and the partition 70 are hardly etched.
[0135]
After performing the plasma treatment, the organic layer 30, the cathode 40, and the sealing can were assembled in the same manner as described above, to produce an organic EL device as Study Example 15. When this device was subjected to a high-temperature storage test at 120 ° C. for 2 hours, no change in current-voltage characteristics before and after storage was observed.
[0136]
However, the organic EL device of this study example 15 was prepared at 85 ° C. with an initial luminance of 2400 cd / m 2. ² , The half life of luminance when the DC drive was performed was 60 hr. The surface state of ITO subjected to the anode surface treatment by oxygen plasma was analyzed by XPS analysis, and as a result, the carbonyl / oxygen peak ratio (P2 / P1) was 0.44.
[0137]
FIG. 14 shows the values of the luminance half-life and the carbonyl / oxygen peak ratio (P2 / P1) in Study Example 15 in addition to FIG. As can be seen from the results shown in FIG. 14, even in the present investigation example 15, although the amount of the carbonyl compound is relatively reduced, the luminance half life is not improved as much as in the case of the UV treatment.
[0138]
For this reason, it was considered that factors other than the carbonyl compound had an effect on the luminance lifetime, and the analysis results were reexamined. As a result of the reexamination, the composition as ITO was changed in Examination Example 15 in which the oxygen plasma treatment was performed, and specifically, In which is a main component of ITO was In. ₂ O ₃ Was found to have a reduced oxygen ratio.
[0139]
As the ITO composition ratio, that is, the oxygen ratio, In appears at 530 eV obtained by separating the peak P0 derived from O1s from the waveform obtained by the XPS analysis on the ITO surface by the curve fitting method. ₂ O ₃ The oxygen / indium peak ratio, which is the ratio of the derived oxygen peak P1 (see FIG. 2 above) and the peak derived from In at 444 eV in the same spectrum (peak derived from In3d, not shown), was used.
[0140]
The oxygen / indium peak ratio was determined by comparing the above-mentioned “UV irradiation study 1” with no UV treatment, UV (normal temperature) treatment (Study Example 1), UV (100 ° C.) treatment (Study Example 2), UV (150 ° C.) ) Processing (Examination Example 3) and oxygen plasma (Examination Example 15) were determined. The result is shown in FIG.
[0141]
From FIG. 15, it can be seen that the oxygen / indium peak ratio is smaller when the surface treatment is performed with oxygen plasma than when the UV treatment is performed, and the ITO composition ratio is largely changed.
[0142]
The mechanism by which the oxygen ratio of ITO is reduced by oxygen plasma is not well understood, but at least the set plasma power is a condition that does not damage even the resist constituting the partition walls, and thus it is considered that the influence of physical sputtering is small.
[0143]
For this reason, it was presumed that it was a chemical effect of oxygen gas, and plasma treatment with a mixed gas of oxygen and argon was studied to reduce this effect. Incidentally, plasma treatment using only argon gas drastically increased the driving voltage of the device, and was not considered because it was not worthy of evaluation.
[0144]
"Study of oxygen-argon plasma": As Study Example 16, using the substrate 10 on which the anode 20, the insulating film 60, and the partition wall 70 were formed, the plasma conditions were such that oxygen gas and argon were adjusted to a pressure of 1.0 Pa. Gas was introduced at a ratio of 1: 9, RF power was set to 50 W, and processing was performed for 200 seconds.
[0145]
After performing this plasma treatment, the organic layer 30, the cathode 40, and the sealing can were assembled in the same manner as described above, to produce an organic EL device as Study Example 16. This device was subjected to an initial luminance of 2400 cd / m at 85 ° C. ² , The luminance half life when DC driving was performed was 93 hours, which was a sufficiently long level.
[0146]
In addition, in this examination example 16, as a result of analyzing the surface state of the ITO (anode) subjected to the plasma treatment by the XPS analysis method, the carbonyl / oxygen peak ratio (P2 / P1) defining the presence of the carbonyl compound was 0.1%. 43. The oxygen / indium peak ratio indicating the ITO composition ratio was 0.17.
[0147]
FIG. 16 shows a value obtained by adding the values of the luminance half-life and the carbonyl / oxygen peak ratio (P2 / P1) in the study example 16 to the above-described FIG. FIG. 17 shows the result obtained by adding the oxygen / indium peak ratio in this study example 16 to the above-mentioned FIG.
[0148]
From this result, it is clarified that, when the anode 20 is subjected to the surface treatment, if there is no abnormality in the ITO composition ratio on the surface, the luminance life is governed by the abundance of the carbonyl compound. It was found to be an influencing factor.
[0149]
From the results of FIG. 16, it was found that the presence of the carbonyl compound on the surface of the anode 20 immediately before the formation of the organic layer was effective if the carbonyl / oxygen peak ratio (P2 / P1) was about 0.43 or less. . This means that high accuracy has been achieved with respect to the fact that the carbonyl / oxygen peak ratio (P2 / P1) as a result from FIG.
[0150]
The substrate temperature during the UV treatment when the carbonyl / oxygen peak ratio (P2 / P1) is 0.43 is determined by comparing the substrate temperature obtained from Study Example 1 to Study Example 3 shown in FIG. It was calculated using the correlation with the oxygen peak ratio (P2 / P1). FIG. 18 shows the correlation between the substrate temperature and the peak ratio.
[0151]
From FIG. 18, the substrate temperature at the time of UV treatment when the carbonyl / oxygen peak ratio (P2 / P1) becomes 0.43 was calculated to be 145 ° C. Since this almost coincides with the change point in FIG. 7 showing the relationship between the substrate temperature and the luminance half life, it was determined that the result was valid.
[0152]
That is, as the surface state of the anode 20 immediately before the formation of the organic layer 30, performing the surface treatment so that the carbonyl / oxygen peak ratio (P2 / P1) on the ITO surface becomes 0.43 or less requires a substrate temperature of 145 ° C. It was found that UV treatment should be performed in the above state.
[0153]
Further, the correlation between the ITO composition ratio and the luminance life was confirmed for those having a small influence of the carbonyl compound. That is, oxygen plasma, oxygen-argon plasma, and UV surface treatment are performed to obtain the oxygen / indium peak ratio so that the carbonyl / oxygen peak ratio (P2 / P1) becomes close to 0.43. An organic EL device was manufactured, and the luminance half life was examined. FIG. 19 shows the result.
[0154]
FIG. 19 is a diagram showing the relationship between the oxygen / indium peak ratio and the luminance half-life, and shows the results of the above-described Examined Example 15, Examined Example 16, and Examined Example 3 in ascending order of oxygen / indium peak ratio. I have.
[0155]
As shown in FIG. 7, the improvement of the luminance life due to the reduction of the carbonyl compound is saturated in about 90 hours. In order to achieve the luminance half life of about 90 hours, FIG. Needs to be 0.16 or more. This is about 90% of the ITO composition ratio before the surface treatment, that is, the oxygen / indium peak ratio = 0.176.
[0156]
That is, as the surface state of the anode 20 immediately before the formation of the organic layer 30, it was found that the value of the oxygen / indium peak ratio after the surface treatment was 90% or more of the value before the surface treatment.
[0157]
In addition, it has been found that the use of plasma with a mixed gas of oxygen and argon suppresses a change in the composition ratio of ITO and reduces the amount of the carbonyl compound, thereby improving the luminance half life.
[0158]
The results of the examination described above are the basis for adopting the surface treatment in consideration of the carbonyl / oxygen peak ratio (P2 / P1) and the oxygen / indium peak ratio in the above-described manufacturing method of the present embodiment, and a more preferable embodiment. This is the basis for adoption.
[0159]
(Other Embodiment 1)
In the above embodiment, an example of a low-molecular-weight organic EL element in which low-molecular-weight organic materials are formed in multiple layers between the upper and lower electrodes of the anode 20 and the cathode 40 has been described. A similar effect can be obtained in a polymer type organic EL device in which a cathode 40 is formed after forming a hole injection transport layer and a light emitting layer of polyparaphenylenevinylene or polyfluorene.
[0160]
That is, before the organic layer is formed, the ITO surface is subjected to a UV heat treatment so that the carbonyl / oxygen peak ratio (P2 / P1) becomes equal to or less than a predetermined value, whereby the life can be extended. In particular, it is effective when a step of forming the insulating film 60 between the ITO electrodes or forming the partition 70 after the formation of ITO is provided.
[0161]
(Other Embodiment 2)
In the above-described embodiment, an example of the passive matrix driving type organic EL element in which the insulating film 60 made of an organic material and the partition 70 are formed on the substrate 10 in addition to the organic layer 30 has been described.
[0162]
FIG. 20 shows a cross-sectional view of an active matrix drive type organic EL element. Reference numeral 20 denotes a thin film transistor, 30 denotes a flattening film made of an organic material, 40 denotes ITO serving as an anode and a cathode, 50 denotes an organic layer, and 60 denotes a cathode and an anode. The reference numeral 60 may be either a metal electrode or a transparent electrode depending on the light extraction direction.
[0163]
Since the flattening film 30 made of an organic material below the ITO 40 is partially exposed, the same problem as that in the case of the passive matrix driving type organic EL element appears during the surface treatment of the ITO 40. That is, the present invention is also effective in an active matrix driving type organic EL device having a flattening film made of an organic material on a thin film transistor. It is more effective when a member made of an organic material is formed after the formation of ITO.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an organic EL device according to an embodiment of the present invention.
FIG. 2 is a view showing an example of a peak derived from O1s in a spectrum obtained by XPS analysis of an ITO surface after ITO surface treatment.
FIG. 3 is a diagram showing a correlation between a peak intensity of a peak derived from C ＝ O in O1s and a peak intensity of a peak derived from C ＝ O in C1s.
FIG. 4 is a schematic cross-sectional view showing the configuration of a substrate with ITO used in the study of the present inventors.
FIG. 5 is a view showing a carbonyl / oxygen peak ratio (P2 / P1) when the processing temperature in the UV processing is changed.
6 is a schematic cross-sectional view of an organic EL element in which an organic layer and a cathode are stacked on ITO in the substrate with ITO shown in FIG. 4;
FIG. 7 is a diagram showing a relationship between a substrate temperature and a luminance half life.
FIG. 8 is a diagram showing a relationship between a carbonyl / oxygen peak ratio (P2 / P1) and a luminance half life.
FIG. 9 is a diagram showing a result of examining voltage-current characteristics after performing a high-temperature storage test on an organic EL element S1 shown in FIG. 1 which has been subjected to UV (150 ° C.) treatment.
FIG. 10 is a diagram showing a relationship between a processing time and a change in element characteristics when UV (150 ° C.) processing is performed as a surface treatment of an anode.
FIG. 11 is a diagram showing a relationship between an ozone flow rate and a current density ratio when a large-sized UV processing apparatus is used.
FIG. 12 is a diagram showing the effect of preliminary introduction of ozone when a large-sized UV processing apparatus is used.
FIG. 13 is a diagram illustrating the effect of plasma assist.
FIG. 14 is a diagram additionally showing the values of the half-life of luminance and the carbonyl / oxygen peak ratio (P2 / P1) in Study Example 15 in FIG.
FIG. 15 is a diagram showing the results of obtaining oxygen / indium peak ratios for UV-treated ITO and oxygen plasma-treated ITO.
FIG. 16 is a diagram additionally showing the values of the half-life of luminance and the carbonyl / oxygen peak ratio (P2 / P1) in Study Example 15 in FIG.
FIG. 17 is a diagram additionally showing the value of the oxygen / indium peak ratio in Study Example 15 in FIG.
FIG. 18 is a diagram showing a correlation between a substrate temperature and a carbonyl / oxygen peak ratio (P2 / P1) during UV processing.
FIG. 19 is a diagram showing the relationship between the oxygen / indium peak ratio and the luminance half life.
FIG. 20 is a cross-sectional view of an active matrix drive type organic EL element.
[Explanation of symbols]
10: substrate, 20: anode as lower electrode layer, 30: organic layer,
40 ... a cathode as an upper electrode layer,
P0: a peak derived from O1s in a spectrum obtained by XPS analysis on the ITO surface;
In appearing at 530 eV obtained by separating the peak P0 derived from P1... O1s by the waveform by the curve fitting method. ₂ O ₃ Derived oxygen peak,
P2... A peak derived from C = O, which appears at 532 eV and is obtained by separating the peak P0 derived from O1s into a waveform by the curve fitting method.

Claims (8)

After a lower electrode layer (20) made of ITO is formed on a substrate (10), a surface treatment of the lower electrode layer is performed, and then one or more layers made of an organic EL material are formed on the lower electrode layer. In a method for manufacturing an organic EL device, an organic layer (30) is formed, and an upper electrode layer (40) is formed on the organic layer.
In the surface treatment step of the lower electrode layer, the surface state of the lower electrode layer immediately before the formation of the organic layer, the carbonyl compound present on the ITO surface constituting the lower electrode layer to a specified amount or less. Surface treatment.
When the amount of the carbonyl compound is not more than the specified amount, the peaks (P1, P2, P3) obtained by separating the peak (P0) derived from O1s from the waveform obtained by the XPS analysis on the ITO surface by curve fitting are used. ), The carbonyl / oxygen peak ratio (P2 / P1), which is the ratio of the peak of oxygen (P1) derived from In ₂ O ₃ at 530 eV and the peak (P2) derived from CＣO at 532 eV, is 0.43. A method for producing an organic EL device, characterized in that: In the surface treatment step of the lower electrode layer (20), the surface treatment is performed so that the composition ratio of oxygen and indium in ITO constituting the lower electrode layer remains within a predetermined amount before and after the surface treatment. Yes,
The term “change within the predetermined amount” refers to a peak obtained by separating the peak (P0) derived from O1s in the spectrum obtained by the XPS analysis method on the ITO surface by the curve fitting method, and appears at 530 eV. The value after the surface treatment in the oxygen / indium peak ratio, which is the ratio between the oxygen peak (P1) derived from In ₂ O ₃ and the peak derived from In at 444 eV in the spectrum, is higher than the value before the surface treatment. The method according to claim 1, wherein the content is 90% or more. The surface treatment of the lower electrode layer (20) is performed by irradiating ultraviolet rays while heating the substrate so that the temperature of the substrate (10) is 145 ° C or higher. 3. The method for producing an organic EL device according to item 1. 4. The organic EL device according to claim 3, wherein the surface of the lower electrode layer (20) is filled with ozone by introducing ozone into the processing tank before performing the processing by the ultraviolet irradiation. 5. Method. 5. The method according to claim 3, wherein the surface treatment of the lower electrode layer is performed by plasma treatment after the treatment by the ultraviolet irradiation. 6. In the surface treatment step of the lower electrode layer (20), a material in which members (60, 70) made of an organic substance are formed on the substrate other than the lower electrode layer is used as the substrate (10). The method for manufacturing an organic EL device according to claim 1. An organic EL device in which a lower electrode layer (20) made of indium tin oxide, one or more organic layers (30) made of an organic EL material, and an upper electrode layer (40) are sequentially formed on a substrate (10). At
In the spectrum obtained by analyzing the surface state of the lower electrode layer before the organic layer is formed by the XPS analysis method as the lower electrode layer, a peak (P0) derived from O1s is separated into waveforms by a curve fitting method. Carbonyl / oxygen, which is the ratio of the peak of oxygen (P1) derived from In ₂ O ₃ appearing at 530 eV and the peak (P2) derived from C 現 れ る O appearing at 532 eV among the peaks (P1, P2, P3) obtained by An organic EL device comprising a device having a peak ratio (P2 / P1) of 0.43 or less. The organic EL device according to claim 7, wherein members (60, 70) made of an organic material are formed on the substrate (10) in addition to the organic layer (30).

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