JP2005209414A - Light-emitting element, manufacturing method of the same, and light-emitting device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element with an improved yield, capable of preventing breaking and exfoliation of an electrode film, and to provide a manufacturing method of the same and a light-emitting device using the same. <P>SOLUTION: A hole injection electrode 9 is formed on a flattened layer of a TFT substrate, and an organic layer 10 is formed on the hole injection electrode 9. The organic layer 10 has a lamination structure of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron injection layer. A pixel separation film 11 is formed on a flattened layer 7 formed between the organic layers 10 of respective pixels. An electron injection electrode 12 is formed on the organic layer 10 and the pixel separation film 11. The electron injection electrode 12 has a lamination structure of a metal thin film 25 and a transparent conductive film 26. The transparent conductive film 26 is formed by a sputtering method using gas containing krypton. By the above, a crystal size of the transparent conductive film is made 60Å or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting element, a manufacturing method thereof, and a light emitting device using the light emitting element.

  With the progress and diversification of the advanced information society in recent years, there has been a demand for a display device that consumes less power than a CRT (cathode ray tube) that has been conventionally used and is thin. In response to such a demand, attention is paid to a display using an organic electroluminescence element (hereinafter referred to as an organic EL element). A display using an organic EL element has features such as low power consumption, high-speed response, thinness, light weight, and low viewing angle dependency, and research and development are being actively conducted because of its high potential.

  In organic EL devices, electrons and holes are injected into the light emitting part from the electron injecting electrode (cathode) and hole injecting electrode (anode), respectively, and these electrons and holes recombine at the emission center to excite organic molecules. When this organic molecule returns to the ground state from the excited state, fluorescence is generated. Such a light emission phenomenon is applied to a display.

  An organic electroluminescence device (hereinafter abbreviated as an organic EL device) includes a plurality of organic EL elements, and each organic EL element constitutes a pixel. In particular, an active matrix type organic EL device having a TFT (thin film transistor) as a switching element for each pixel can hold display data for each pixel, so that a large screen and high definition can be achieved. It is considered as the leading role of the display device.

  In a normal organic EL element, a hole injection electrode made of a transparent conductive film, a light emitting layer made of an organic material, and an electron injection electrode are sequentially provided on a glass substrate. Thereby, the light generated in the light emitting layer passes through the hole injection electrode made of a transparent conductive film and is extracted to the outside from the back side of the glass substrate.

  On the other hand, a structure has been proposed in which light generated in the light emitting layer is extracted from the upper surface side by forming an electron injection electrode on the upper side of each organic EL element using a transparent conductive film (for example, Patent Document 1). To 4). A structure in which light generated by the light emitting layer is extracted from the upper surface side is called a top emission structure.

In the organic EL device having the top emission structure, the color filter or the color conversion layer can be disposed on the upper electron injection electrode, so that the manufacture becomes easy. In an organic EL device having an active matrix top emission structure, light generated by the light emitting layer is extracted outside without being blocked by a plurality of TFTs on the glass substrate. Therefore, the aperture ratio of the pixel (the ratio of the area of the light emitting portion in the pixel) is improved.
US Pat. No. 5,776,623 Japanese Patent Laid-Open No. 10-162959 Japanese Patent No. 3254417 JP 2001-085157 A

  However, in the conventional organic EL device having an active matrix type top emission structure, the thickness of the electron injection electrode is set to a predetermined value in order to transmit the light generated from the light emitting layer through the electron injection electrode on the upper surface side and extract the light to the outside. It is necessary to make it as thin as possible. As a result, the electron injection electrode is likely to be cut due to the unevenness of the base, and the yield is lowered.

  Further, in the manufacture of an organic EL device having an active matrix type top emission structure, when the thickness of the electron injection electrode is increased in order to increase the yield, the stress applied to the electron injection electrode is increased and the electron injection electrode is peeled off.

  An object of the present invention is to provide a light-emitting element that can prevent film breakage and peeling of an electrode and that can improve yield, a manufacturing method thereof, and a light-emitting device using the light-emitting element.

  A light-emitting element according to a first invention includes a first electrode, an organic film including a light-emitting layer, and a second electrode in order, and the second electrode includes a conductive film having a crystallite size of 60 mm or less. It is a waste.

  In the light emitting device according to the first invention, since the second electrode includes a conductive film having a crystallite size of 60 mm or less, the stress of the conductive film can be reduced. Therefore, the thickness of the second electrode is increased. Even if it does not peel off. In addition, since the thickness of the second electrode can be increased, it is possible to prevent the second electrode from being cut and to improve the yield.

  Further, when the crystallite size is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic film side through the conductive film. As a result, the reliability of the light emitting element can be improved.

  The conductive film may have a sheet resistance value smaller than 12.5Ω / □. Thereby, when a light-emitting device is comprised using a some light emitting element, luminance in-plane distribution can be made small.

  The conductive film may include at least one of krypton, xenon, and radon. When a conductive film is formed by a sputtering method using at least one of krypton, xenon, and radon as a sputtering gas, a conductive film having a crystallite size of 60 mm or less can be formed. In this case, the conductive film contains at least one of krypton, xenon, and radon.

  The conductive film may have a thickness of 2400 mm or more. In this case, the conductive film is not cut. Thereby, the yield can be improved.

  The conductive film may include an inorganic conductive film that transmits light emitted from the light emitting layer. In this case, since the second electrode includes an inorganic conductive film that transmits light, light emitted from the light-emitting element can be extracted from the second electrode side.

  The second electrode may further include a metal film stacked on the conductive film. In this case, the microcavity effect of the metal film can be positively utilized, and the external extraction efficiency is increased.

  A light emitting device according to a second invention includes a substrate and one or a plurality of organic electroluminescent elements disposed on the substrate, and each of the organic electroluminescent elements includes a first electrode and a light emitting layer. An organic film and a second electrode are included in order, and the second electrode includes a conductive film having a crystallite size of 60 mm or less.

  In the light emitting device according to the second invention, since the stress of the conductive film can be reduced by including the conductive film having a crystallite size of 60 mm or less, the thickness of the second electrode is increased. Even if it does not peel off. In addition, since the thickness of the second electrode can be increased, it is possible to prevent the second electrode from being cut and to improve the yield.

  Further, when the crystallite size is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic film side through the conductive film. As a result, the reliability of the light emitting device can be improved.

  In the method for manufacturing a light-emitting element according to the third invention, a conductive film having a crystallite size of 60 mm or less is formed on an organic film including a light-emitting layer.

  In the method for manufacturing the light emitting element according to the third invention, since the second electrode includes a conductive film having a crystallite size of 60 mm or less, the stress of the conductive film can be reduced. Even if the thickness is increased, peeling does not occur. In addition, since the thickness of the second electrode can be increased, it is possible to prevent the second electrode from being cut and to improve the yield.

  Further, when the crystallite size is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic film side through the conductive film. As a result, the reliability of the light emitting element can be improved.

  The conductive film may be formed by a sputtering method using a gas containing at least one of krypton, xenon, and radon. In this case, when a conductive film is formed by a sputtering method using at least one of krypton, xenon, and radon as a sputtering gas, a conductive film having a crystallite size of 60 mm or less can be formed.

  According to the present invention, since the second electrode includes the conductive film having a crystallite size of 60 mm or less, the stress of the conductive film can be reduced. Therefore, even if the thickness of the second electrode is increased, peeling is caused. Does not occur. In addition, since the thickness of the second electrode can be increased, it is possible to prevent the second electrode from being cut and to improve the yield.

  Further, when the crystallite size is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic film side through the conductive film. As a result, the reliability of the light emitting element and the light emitting device can be improved.

  Hereinafter, an organic electroluminescence device (hereinafter referred to as an organic EL device) will be described as an example of a light emitting device according to the present invention.

  FIG. 1 is a schematic cross-sectional view of an organic EL device according to a first embodiment of the present invention. The organic EL device of FIG. 1 is composed of a plurality of organic electroluminescence elements (hereinafter referred to as organic EL elements) arranged in a matrix. Each organic EL element constitutes a pixel.

  Here, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction. The X direction and the Y direction are directions parallel to the surface of the glass substrate 1, and the Z direction is a direction perpendicular to the surface of the glass substrate 1. The plurality of pixels are arranged along the X direction and the Y direction.

  An active layer 2 made of polycrystalline silicon or the like is formed on a glass substrate 1, and a TFT (thin film transistor) 3 having a gate oxide film and a gate electrode is formed on the active layer 2. On the active layer 2, a plurality of wiring layers 5a, 5b, 5c made of Al are formed. The drain electrode of the TFT 3 is connected to the wiring layer 5a, and the source electrode of the TFT 3 is connected to the wiring layer 5b.

  An interlayer insulating film 4 is formed on the active layer 2 except for the TFT 3, and a planarizing layer 7 made of polyimide resin or the like is formed so as to cover the TFT 3 and the interlayer insulating film 4. Thus, the glass substrate 1 having the plurality of TFTs 3 and the planarizing layer 7 is referred to as a TFT substrate 8.

  A hole injection electrode (anode) 9 made of a metal such as Mo (molybdenum) is formed on the planarizing layer 7 of the TFT substrate 8 for each pixel. Each hole injection electrode 9 is connected to the wiring layer 5a.

  An organic layer 10 is formed on the hole injection electrode 9. For example, when the same emission color is adjacent in the X direction, the organic layer 10 is formed to extend in a stripe shape along the X direction, and when the same emission color is adjacent in the Y direction, the organic layer 10 is It is formed to extend in a stripe shape along the Y direction. When the same emission color is not adjacent, the organic layer 10 is formed for each pixel.

 The organic layer 10 has a stacked structure of, for example, a hole injection layer, a hole transport layer, a light emitting layer, and an electron injection layer. In this case, the light emitting layer has electron transport properties.

The hole injection layer is made of, for example, CuPc (copper phthalocyanine). The hole transport layer may be, for example, NPB (N, N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine; N, N′-Di (naphthalen-1-yl) -N, N′— diphenyl-benzidine). The light emitting layer is made of, for example, Alq ₃ (Tris (8-hydroxyquinolinato) aluminum). The electron injection layer is made of, for example, Li ₂ O, LiF, BCP (bathocuproin), Cs (cesium), or the like.

  In the present embodiment, the hole injection electrode 9 corresponds to the first electrode, the organic layer 10 corresponds to the organic film, the electron injection electrode 12 corresponds to the second electrode, the transparent conductive film 26 is the conductive film, It corresponds to an inorganic conductive film, and the metal thin film 25 corresponds to a metal film.

  Various known organic materials can be used as the material of the organic layer 10 of the organic EL element.

  An insulating pixel separation film 11 extending in a grid pattern in the X and Y directions is formed on the planarization layer 7 between the organic layers 10 of each pixel.

  An electron injection electrode (cathode) 12 is formed on the entire upper surface of the organic layer 10 and the pixel separation film 11. The electron injection electrode 12 has a laminated structure of a metal thin film and a transparent conductive film. As a material of the metal thin film, for example, a metal or an alloy such as Ag (silver), Al (aluminum), Mg (magnesium), Ca (calcium), or Sc (scandium) is used. As a material of the transparent conductive film, for example, IZO (indium / zinc oxide), ITO (indium / tin oxide), or the like is used.

  Next, a method for manufacturing the organic EL device of FIG. 1 will be described.

  A plurality of hole injection electrodes 9 are formed for each pixel on the TFT substrate 8 of FIG. 1 by sputtering and photolithography.

  Next, after forming a polyimide film by applying a photosensitive polyimide resin on the TFT substrate 8 and the hole injection electrode 9, a pixel separation film extending in a lattice shape in the X and Y directions by performing exposure and development. 11 is formed.

  Thereafter, on the hole injection electrode 9 between the pixel separation films 11, for example, an organic layer 10 having a laminated structure of a hole injection layer, a hole transport layer, a light emitting layer, and an electron injection layer is formed by using a vacuum evaporation method by current heating. .

  Thereafter, a metal thin film of the electron injection electrode 12 is formed on the organic layer 10 and on the entire upper surface of the pixel separation film 11 by a vacuum vapor deposition method by current heating. Further, a transparent conductive film is formed on the metal thin film by ECR (Electron Cyclotron Resonance) sputtering. As a sputtering gas, Kr (krypton) is used. Xe (xenon) or Rn (radon) may be used instead of Kr, and two or more of Kr, Xe and Rn may be mixed and used.

  By using such Kr, Xe or Rn as a sputtering gas, a transparent conductive film having a crystallite size of 60 mm or less can be formed.

  The transparent conductive film is formed to have a thickness of 2400 mm or more. Thereby, the sheet resistance of the transparent conductive film can be reduced to 12.5Ω / □ or less.

  In this embodiment, since the electron injection electrode 12 includes a transparent conductive film having a crystallite size of 60 mm or less, the stress of the transparent conductive film can be reduced. Therefore, the thickness of the electron injection electrode 12 is increased. No peeling occurs. Further, since the thickness of the transparent conductive film can be increased, it is possible to prevent the electron injecting electrode 12 from being cut and to improve the yield.

  Further, when the crystallite size of the transparent conductive film is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic layer 10 side through the transparent conductive film. As a result, the reliability of the organic EL device can be improved.

  Furthermore, since the electron injection electrode 12 includes a metal thin film, the microcavity effect of the metal thin film can be actively used, and light generated by the light emitting layer 10 can be extracted with high efficiency from the electron injection electrode 12 side. Can do.

  On the other hand, the transparent conductive film may be provided as a single layer without including the metal thin film of the electron injection electrode 12. In this case, since the electron injection electrode 12 includes an inorganic conductive film that transmits light, the dependency on the viewing angle is small, and light generated from the light emitting layer 10 can be effectively extracted from the electron injection electrode 12 side.

  The structure of the organic EL element is not limited to the above structure, and various structures can be used. For example, an electron transport layer may be provided between the light emitting layer and the electron injection layer. Further, the hole transport layer may not be provided.

  Furthermore, the material of the pixel separation film 11 is not limited to polyimide resin, and other resins such as acrylic resin can be used, or inorganic materials such as SiN can be used.

  In the above embodiment, the case where the present invention is applied to an active matrix type organic EL device has been described. However, the present invention is not limited to an active matrix type, and a simple matrix type (passive type) having no TFT. The same can be applied to the organic EL device.

  Furthermore, as described above, the present invention can obtain a greater effect when applied to an organic EL device having a top emission structure. However, the present invention is also applied to an organic EL device having a structure in which light is extracted from the back side of the substrate. It can also be applied.

  Note that an electron injection electrode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and a hole injection electrode may be laminated on the TFT substrate 8 in this order.

  Next, FIG. 2A is a schematic plan view of the organic EL device according to the second embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line AA of the organic EL device of FIG. FIG.

  The organic EL device of FIG. 2 has a top emission structure and is configured by a single organic EL element. This organic EL device is used as a backlight of a liquid crystal display device, for example.

  A hole injection electrode (anode) 102 is formed on the glass substrate 101. An organic layer 103 is formed on the hole injection electrode 102 made of metal, alloy, or the like. The organic layer 103 has a stacked structure of, for example, a hole injection layer, a hole transport layer, a light emitting layer, and an electron injection layer. In this case, the light emitting layer has electron transport properties.

  In addition, an insulating protective film 104 is formed so as to surround the organic layer 103.

  On the organic layer 103 and the protective film 104, an electron injection electrode (cathode) 105 made of a metal thin film and a transparent conductive film is formed. The configuration and formation method of the electron injection electrode 105 are the same as the configuration and formation method of the electron injection electrode 12 according to the first embodiment. In the present embodiment, the electron injection electrode 12 corresponds to the second electrode.

  Also in this embodiment, a transparent conductive film having a crystallite size of 60 mm or less can be formed by using Kr, Xe, or Rn as a sputtering gas.

  The transparent conductive film is formed to have a thickness of 2400 mm or more. Thereby, the sheet resistance of the transparent conductive film can be reduced to 12.5Ω / □ or less.

  In the present embodiment, since the electron injection electrode 12 includes a transparent conductive film having a crystallite size of 60 mm or less, the stress of the transparent conductive film can be reduced, so that the thickness of the electron injection electrode 12 is increased. Even if it does not peel off. Further, since the thickness of the transparent conductive film can be increased, it is possible to prevent the electron injecting electrode 12 from being cut and to improve the yield.

  Further, when the crystallite size of the transparent conductive film is 60 mm or less, the columnar crystal structure is not formed, so that it is possible to prevent moisture from the outside from entering the organic layer 10 side through the transparent conductive film. As a result, the reliability of the organic EL device can be improved.

Further, since the electron injection electrode 12 includes a metal thin film, the microcavity effect of the metal thin film can be positively used, and the external extraction efficiency is increased.
The transparent conductive film may be provided as a single layer without providing the metal thin film of the electron injection electrode 12. In this case, since the electron injection electrode 12 includes an inorganic conductive film that transmits light, light emitted from the organic EL element can be extracted from the electron injection electrode 12 side.

  Further, by using a metal substrate instead of the glass substrate 1, a thin and highly rigid light source is realized.

  Hereinafter, in Examples 1 to 3 and Comparative Examples 1 and 2, organic EL devices having the structure of FIG. 1 were manufactured under different conditions. In Example 1, a plurality of organic EL devices with different transparent conductive film thicknesses were produced. In Example 1 and Example 2, a transparent conductive film was formed using Kr as a sputtering gas. The transparent conductive film was formed using Xe as the sputtering gas.

  In Comparative Examples 1 and 2, a transparent conductive film was formed using Ar as the sputtering gas. Each example will be described below.

(Example 1)
FIG. 3 is a partially enlarged view of the organic EL device manufactured in Example 1.

A hole injection electrode 9 made of Mo (molybdenum) having a thickness of 1000 mm is formed on the TFT substrate 8 having the structure of FIG. 1, and then hole injection made of CuPc having a thickness of 100 mm is formed on the hole injection electrode 9 as an organic layer 10. The layer 21, the hole transport layer 22 made of NPB having a thickness of 500 mm, the light emitting layer 23 made of Alq ₃ having a thickness of 500 mm, and the electron injection layer 24 made of Li ₂ O having a thickness of 15 mm were laminated in this order. Further, a metal thin film 25 made of Ag having a thickness of 150 mm and a transparent conductive film 26 made of IZO (indium / zinc oxide) were sequentially formed on the organic layer 10 as the electron injection electrode 12. The thickness of the transparent conductive film 26 was 3000 mm, 5000 mm, and 1000 mm.

The hole injection electrode 9 was formed by RF (high frequency) sputtering. Ar (argon) gas was used as the sputtering gas, the pressure during film formation was 1.5 × 10 ⁻¹ Pa, and the high frequency output was 200 W. Each layer of the organic layer 10 and the metal thin film 25 were formed using a vacuum evaporation method by energization heating, and the pressure during film formation was set to 5.0 × 10 ⁻¹ Pa.

Further, the transparent conductive film 26 was formed by ECR (Electron Cyclotron Resonance) sputtering. As a sputtering gas, a mixed gas of Kr (krypton) and O ₂ (oxygen) (mixing ratio: 0.3%) was used, the pressure during film formation was 1.9 × 10 ⁻¹ Pa, and the high frequency output was 300 W. did.

(Comparative Example 1)
In Comparative Example 1, an organic EL device was produced in the same manner as in Example 1 except for the method for forming the transparent conductive film 26 of the electron injection electrode 12. In Comparative Example 1, a mixed gas of Ar gas and O ₂ gas (0.3%) was used as the sputtering gas, the pressure during film formation was 1.9 × 10 ⁻¹ Pa, and the high frequency output was 300 W. The thickness of the transparent conductive film 26 was 3000 mm, 5000 mm, and 1000 mm.

(Evaluation)
The crystallinity of the three types of transparent conductive films 26 produced in Example 1 and Comparative Example 1 was confirmed using X-ray diffraction. For comparison, the X-ray diffraction of glass (Corning # 1737) was also measured.

  4 is a diagram showing an X-ray diffraction spectrum of the transparent conductive film 26 of the organic EL device manufactured in Example 1, and FIG. 5 is an X-ray diffraction spectrum of the transparent conductive film 26 of the organic EL device manufactured in Comparative Example 1. FIG.

  As shown in FIG. 5, in the case where the thickness of the transparent conductive film 26 in Comparative Example 1 was 1000 mm, a diffraction peak from the crystal plane was not seen, whereas the thickness of the transparent conductive film 26 was 3000 mm and In the case of 5000 mm, a sharp diffraction peak from the (222) plane, a sharp diffraction peak from the (433) plane, and a sharp diffraction peak from the (332) plane appeared. This shows that the transparent conductive film 26 having a thickness of 3000 mm and 5000 mm has high crystallinity.

  On the other hand, as shown in FIG. 4, when the thickness of the transparent conductive film 26 formed in Example 1 was 1000 mm, no diffraction peak was observed from the crystal plane. Furthermore, when the transparent conductive film 26 had a thickness of 3000 mm and 5000 mm, a broad diffraction peak from the (222) plane was observed, but diffraction peaks from the (332) plane and the (433) plane were observed. There wasn't. As a result, it was confirmed that the transparent conductive film 26 produced in Example 1 had low crystallinity and was in an amorphous or microcrystalline state.

  Next, the sheet resistance of each transparent conductive film 26 in Example 1 and Comparative Example 1 was measured. The measurement results are shown in Table 1.

  FIG. 6 is a diagram showing the relationship between the thickness of each transparent conductive film 26 and the sheet resistance in Example 1 and Comparative Example 1.

  The vertical axis in FIG. 6 indicates the sheet resistance (Ω / □), and the horizontal axis indicates the thickness (Å). In Example 1 and Comparative Example 1, when the thickness of the transparent conductive film 26 was 1000 mm, the value of the sheet resistance was as large as 30Ω / □ or more. On the other hand, when the thickness of the transparent conductive film 26 was 3000 mm and 5000 mm, the value of the sheet resistance was as small as 10Ω / □ or less.

  Next, the luminance in-plane distribution of the organic EL devices produced in Example 1 and Comparative Example 1 was measured. The measurement results are shown in Table 2.

  FIG. 7 is a diagram showing the relationship between the sheet resistance and the luminance in-plane distribution of the organic EL devices in Example 1 and Comparative Example 1.

  The vertical axis in FIG. 7 indicates the luminance in-plane distribution (%), and the horizontal axis indicates the sheet resistance (Ω / □). In addition, in the organic EL device of Comparative Example 1 having a thickness of 3000 Å and 5000 透明 of the transparent conductive film 26, the transparent conductive film 26 was peeled off, so the measurement result of the luminance in-plane distribution was not obtained.

  As shown in FIG. 7, the luminance in-plane distribution value increased as the sheet resistance value increased. A method for measuring the luminance in-plane distribution will be described later.

  Generally, the luminance in-plane distribution that cannot be recognized by human vision in the displayed still image is assumed to be ± 5% or less. Therefore, in FIG. 7, in order to make the luminance in-plane distribution ± 5% or less, the sheet resistance value needs to be 12.5Ω / □ or less.

  From the result of FIG. 6, it is understood that the thickness of the transparent conductive film 26 needs to be 2400 mm or more in order to make the sheet resistance value 12.5Ω / □ or less.

  Next, FIG. 8 is a diagram for explaining a method for measuring the luminance in-plane distribution.

  In FIG. 8, the major axis direction of the panel (display screen) 600 of the organic EL device is the x direction, and the minor axis direction is the y direction.

  First, when measuring the luminance in-plane distribution, the x direction and the y direction of the panel 600 shown in FIG. 8 are each divided into 25 points. Next, the luminance of 625 (25 × 25) points is measured. An average value of luminance of 625 points is calculated, a difference between the luminance of each point and the average value is calculated, and a percentage of the calculated value with respect to the average value is calculated. The maximum value among the calculated percentages is set as the luminance in-plane distribution.

  Next, since the transparent conductive film 26 of the organic EL device produced in Comparative Example 1 was peeled off, the transparent conductive film 26 was formed on the substrate having a diameter of 3 inches using the same conditions and the same formation method as in Example 1 and Comparative Example 1. The stress was measured. Also in this case, the thickness of the transparent conductive film 26 was 1000 mm, 3000 mm, and 5000 mm. Table 3 shows the measurement results.

  FIG. 9 is a diagram showing the relationship between the thickness and stress of the transparent conductive film 26 in Example 1 and Comparative Example 1.

The vertical axis in FIG. 9 represents stress (dyn / cm ² ), and the horizontal axis represents thickness (Å). In the case of Example 1, the stress did not change greatly regardless of whether the thickness of the transparent conductive film 26 was 1000 mm, 3000 mm, or 5000 mm, and showed a substantially constant value. Thereby, in Example 1, even if the thickness of the transparent conductive film 26 is 2400 mm or more, the stress can be kept small.

  On the other hand, in the case of Comparative Example 1, it was found that the stress increased as the thickness of the transparent conductive film 26 increased from 1000 to 3000 to 5000.

  Next, the crystallite size of the transparent conductive film 26 of the organic EL device produced in Example 1 and Comparative Example 1 was determined.

  The crystallite size of the transparent conductive film 26 of the organic EL device produced in Example 1 and Comparative Example 1 uses the peak intensity of the X-ray diffraction spectrum and Scherrer's equation shown in FIGS. Calculated by

  The Scherrer equation is shown below.

dc = 0.9λ / βcos θ (1)
Here, dc represents a crystallite size, λ represents an X-ray wavelength (CuKα ray: 0.15418 nm), β represents an integral width (integrated intensity / peak intensity), and θ represents a diffraction angle (rad). Show.

  Table 4 shows the calculation results of the crystallite size of the transparent conductive film 26 of the organic EL device produced in Example 1 and Comparative Example 1.

  FIG. 10 is a diagram showing the relationship between the thickness of the transparent conductive film 26 and the crystallite size in Example 1 and Comparative Example 1. The vertical axis represents the crystallite size (Å), and the horizontal axis represents the thickness (Å).

  As shown in FIG. 10, the crystallite size of the transparent conductive film 26 in Example 1 is 26 mm when the thickness of the transparent conductive film 26 is 1000 mm, and when the thickness of the transparent conductive film 26 is 3000 mm. Is 32 mm, and is 48 mm when the thickness of the transparent conductive film 26 is 5000 mm.

  The crystallite size of the transparent conductive film 26 in Comparative Example 1 is 29 mm when the thickness of the transparent conductive film 26 is 1000 mm, and 79 mm when the thickness of the transparent conductive film 26 is 3000 mm, When the thickness of the transparent conductive film 26 is 5000 mm, it is 138 mm.

  In FIG. 10, the range of crystallite size of the transparent conductive film 26 having a thickness of 3000 mm and 5000 mm in Comparative Example 1 in which peeling occurred was set to range a, and the transparent conductive film having a thickness of 1000 mm in Comparative Example 1 in which peeling did not occur. The range of distribution of the crystallite size of 26 and the crystallite size of the transparent conductive film 26 having a thickness of 1000 mm, 3000 mm, and 5000 mm in Example 1 is defined as a range b. As shown in FIG. 10, when the crystallite size is 60 mm or less, the transparent conductive film 26 does not peel off.

  In addition, the luminance in-plane distribution is ± 14.6% in the case of the transparent conductive film 26 having a thickness of 1000 mm in Comparative Example 1, and the luminance in-plane distribution is ± 14.6%. The luminance in-plane distribution is ± 13.5%, both of which greatly exceed ± 5%.

  On the other hand, as shown in Table 2, in the case of the transparent conductive film 26 having a thickness of 3000 mm in Example 1, the luminance in-plane distribution is ± 4.2%, and the transparent conductive film 26 having a thickness of 5000 mm in Example 1 is used. In this case, the luminance in-plane distribution was ± 2.8%, both of which were suppressed to ± 5% or less, and good results were obtained.

  From the above, in order to make the luminance in-plane distribution ± 5% or less, the sheet resistance value needs to be 12.5Ω / □ or less, and the sheet resistance value is 12.5Ω / □. In order to achieve the following, it has been found that the transparent conductive film 26 needs to have a thickness of 2400 mm or more and a crystallite size of 60 mm or less.

  Further, the reason why the electron injection electrode 12 was peeled off when the thickness of the transparent conductive film 26 of Comparative Example 1 was 2400 mm or more and 3000 mm or 5000 mm was as shown in the results of FIG. It is presumed that the crystallinity increases and the stress increases as the thickness of the conductive film 26 increases.

  On the other hand, the transparent conductive film 26 of Example 1 has a low crystallinity and is considered to be in an amorphous or microcrystalline state, as shown in the results of FIG. Therefore, it is presumed that no peeling occurs.

From the above results, the crystallite size can be reduced to 60 mm or less by forming the transparent conductive film 26 by sputtering using a mixed gas of Kr gas and O ₂ gas as the sputtering gas. No peeling occurs even if the stress is reduced and the thickness of the transparent conductive film 26 is increased. Further, since the thickness of the transparent conductive film 26 can be increased, it is possible to prevent the transparent conductive film 26 from being cut and to improve the yield.

(Example 2)
FIG. 11 is a partially enlarged view of the organic EL device manufactured in Example 2.

  Hereinafter, the difference between the organic EL device of Example 2 and the organic EL device manufactured in Example 1 will be described.

In the organic EL device of Example 2, a light-emitting layer 23a made of Alq ₃ having a thickness of 600 mm was formed instead of the light-emitting layer 23 made of Alq ₃ having a thickness of 500 mm in Example 1. Further, instead of the electron injection layer 24 made of Li ₂ O having a thickness of 15 mm in Example 1, an electron injection layer 24a made of a co-deposited layer of BCP (bathocuproine) and Cs (cesium) having a thickness of 200 mm was formed.

  Further, instead of the electron injection electrode 12 including the metal thin film 25 made of Ag having a thickness of 150 mm and the transparent conductive film 26 made of IZO (indium / zinc oxide) in Example 1, a 3000 mm thick IZO (indium / zinc) is used. An electron injection electrode 12a made of a single layer of the transparent conductive film 26 made of an oxide was formed. The thickness of the transparent conductive film 26 was 3000 mm.

  The method for forming the hole injection electrode 9, the organic layer 10a, and the electron injection electrode 12a is the same as that in the first embodiment.

(Example 3)
In Example 3, an organic EL device was produced in the same manner as in Example 1 except for the method of forming the transparent conductive film 26 of the electron injection electrode 12. In Example 3, a mixed gas of Xe gas and O ₂ gas (0.3%) was used as the sputtering gas, the pressure during film formation was 1.9 × 10 ⁻¹ Pa, and the high frequency output was 300 W. The thickness of the transparent conductive film 26 was 3000 mm.

(Comparative Example 2)
In Comparative Example 2, an organic EL device was produced in the same manner as in Example 2 except for the method of forming the transparent conductive film 26 of the electron injection electrode 12a. In Comparative Example 2, a mixed gas of Ar gas and O ₂ gas (0.3%) was used as the sputtering gas, the pressure during film formation was 1.9 × 10 ⁻¹ Pa, and the high frequency output was 300 W. The thickness of the transparent conductive film 26 was 3000 mm.

(Evaluation)
For Examples 2 and 3 and Comparative Example 2, the in-plane luminance distribution, sheet resistance, and crystallite size of the transparent conductive film 26 were measured in the same manner as in Example 1 and Comparative Example 1.

  Table 5 shows the luminance in-plane distribution, sheet resistance, and crystallite size of the transparent conductive film of the organic EL devices manufactured in Examples 1 to 3 and Comparative Examples 1 and 2 having a transparent conductive film thickness of 3000 mm.

  As described above, in the organic EL device manufactured in Example 1, the luminance in-plane distribution is ± 4.2%, the sheet resistance is 9.8Ω / □, and the crystallite size of the transparent conductive film 26 is 32 mm. Met.

  On the other hand, in the organic EL device produced in Comparative Example 1, since the transparent conductive film 26 was peeled off, the luminance in-plane distribution could not be measured, the sheet resistance was 10.2Ω / □, and the crystallite size of the transparent conductive film was It was 138cm.

  Further, in the organic EL device produced in Example 2, the luminance in-plane distribution was ± 3.7%, the sheet resistance was 9.8Ω / □, and the crystallite size of the transparent conductive film 26 was 32 mm. .

  On the other hand, in the organic EL device produced in Comparative Example 2, since the transparent conductive film 26 was peeled off, the luminance in-plane distribution could not be measured, the sheet resistance was 10.2Ω / □, and the crystallite size of the transparent conductive film was It was 138cm.

  From the comparison between Example 1 and Comparative Example 1 and the comparison between Example 2 and Comparative Example 2, when forming the transparent conductive film 26, the crystallinity is improved by using Kr having a larger atomic size than Ar as the sputtering gas. It can be seen that the transparent conductive film 26 is formed in a low state, either amorphous or microcrystalline.

  As a result, since the crystallite size can be reduced to 60 mm or less by using the sputtering gas as Kr gas, even if the stress of the transparent conductive film 26 is reduced and the thickness of the transparent conductive film 26 is increased to 2400 mm or more. No peeling occurs. Further, since the thickness of the transparent conductive film 26 can be increased, it is possible to prevent the transparent conductive film 26 from being cut and to improve the yield.

  Further, in the organic EL device produced in Example 3, the luminance in-plane distribution was ± 4.4%, the sheet resistance was 11.2Ω / □, and the crystallite size of the transparent conductive film 26 was 40 mm.

  From the comparison between Example 3 and Comparative Example 1, when the transparent conductive film 26 is formed, the crystallinity is low by using Xe having a larger atomic size than Ar as the sputtering gas, and it is in an amorphous or microcrystalline state. It can be seen that the transparent conductive film 26 is formed.

  As a result, by forming the transparent conductive film 26 by sputtering using Xe gas as the sputtering gas, the crystallite size can be reduced to 60 mm or less, so that the stress of the transparent conductive film 26 is reduced and the transparent conductive film 26 is reduced. Even if the thickness of 26 is increased to 2400 mm or more, peeling does not occur. Further, since the thickness of the transparent conductive film 26 can be increased, it is possible to prevent the transparent conductive film 26 from being cut and to improve the yield.

  From the above, it can be seen that it is necessary to form the transparent conductive film 26 by sputtering using Kr gas or Xe gas having a large atomic size. Further, it can be presumed that the same result can be obtained even when an Rn gas having a larger atomic size is used as the sputtering gas besides Kr gas or Xe gas.

  Further, as a result of comparing the organic EL devices produced in Example 1 and Example 2, it can be suppressed to within ± 5% regardless of whether or not the metal thin film 25 is present in the electron injection electrode 12. The sheet resistances are both 9.8 Ω / □ lower than 12.5 Ω / □, and the crystallite size of the transparent conductive film 26 is 32 小 さ い smaller than 60 両 者.

  From the above, regardless of whether or not the metal thin film 25 is present on the electron injection electrode 12, the transparent conductive film 26 is formed by sputtering using Kr gas, Xe gas or Rn gas as the sputtering gas. It can be seen that peeling of the conductive film 26 can be prevented and film breakage of the transparent conductive film 26 can be prevented.

    The present invention can be used for a light emitting device.

1 is a schematic cross-sectional view of an organic EL device according to a first embodiment of the present invention. (A) is a typical top view of the organic electroluminescent apparatus which concerns on the 2nd Embodiment of this invention, (b) is the sectional view on the AA line of the organic electroluminescent apparatus of (a). 1 is a partially enlarged view of an organic EL device manufactured in Example 1. FIG. 2 is a diagram showing an X-ray diffraction spectrum of a transparent conductive film of an organic EL device produced in Example 1. FIG. It is a figure which shows the X-ray-diffraction spectrum of the transparent conductive film of the organic electroluminescent apparatus produced in the comparative example 1. It is a figure which shows the thickness of each transparent conductive film in Example 1 and Comparative Example 1, and the relationship of sheet resistance. It is a figure which shows the relationship between the sheet resistance of the organic electroluminescent apparatus in Example 1 and the comparative example 1, and luminance in-plane distribution. It is a figure for demonstrating the measuring method of luminance in-plane distribution. It is a figure which shows the relationship between the thickness of the transparent conductive film in Example 1 and Comparative Example 1, and stress. It is a figure which shows the relationship between the thickness of a transparent conductive film in Example 1 and Comparative Example 1, and a crystallite size. 6 is a partially enlarged view of an organic EL device produced in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 1st electrode 10 Organic layer 12 Electron injection electrode 23 Light emitting layer 24 Electron injection layer 26 Transparent electrically conductive film 25 Metal thin film

Claims (9)

A first electrode;
An organic film including a light emitting layer;
A second electrode in order,
The light emitting element, wherein the second electrode includes a conductive film having a crystallite size of 60 mm or less. The light emitting device according to claim 1, wherein the conductive film has a sheet resistance value smaller than 12.5Ω / □. The light emitting device according to claim 1, wherein the conductive film contains at least one of krypton, xenon, and radon. The light emitting device according to claim 1, wherein the conductive film has a thickness of 2400 mm or more. The light-emitting element according to claim 1, wherein the conductive film includes an inorganic conductive film that transmits light emitted from the light-emitting layer. The light emitting device according to claim 1, wherein the second electrode further includes a metal film stacked on the conductive film. A substrate,
One or more light emitting elements disposed on the substrate,
Each of the light emitting elements is
A first electrode;
An organic film including a light emitting layer;
A second electrode in order,
The light emitting device, wherein the second electrode includes a conductive film having a crystallite size of 60 mm or less. A method for manufacturing a light-emitting element, comprising forming a conductive film having a crystallite size of 60 mm or less on an organic film including a light-emitting layer. The method for manufacturing a light-emitting element according to claim 7, wherein the conductive film is formed by a sputtering method using a gas containing at least one of krypton, xenon, and radon.

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