Organic light-emitting element, film-forming method, and film-forming apparatus

Abstract

To provide an organic light emitting element with higher reliability, a deposition method for forming the organic light emitting element with higher reliability, and a deposition equipment.SOLUTION: In an organic light emitting element, a light emitting layer is provided between the cathode layer and the anode layer. An electron injection layer is provided between the cathode layer and the light-emitting layer. The hole injection layer is provided between the anode layer and the emission layer. The electron transport layer is provided between the electron injection layer and the emission layer. The hole transport layer is provided between the hole injection layer and the emission layer. The cathode layer is composed of a transparent conductive layer. The electron injection layer contains a first component including at least one of silver, aluminum, copper, gold, and platinum, and a second component including at least one of an alkali metal, an alkaline earth metal, fluoride of an alkali metal, fluoride of an alkaline earth metal, and lanthanoids.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an organic light-emitting device, a film-forming method, and a film-forming apparatus.

Background Art

[0002] In an organic light-emitting device, electrons are injected from a cathode electrode into a light-emitting layer, holes are injected from an anode electrode, and electrons and holes are recombined in the light-emitting layer to generate light.

[0003] Here, as a main electrode (for example, a cathode) of an organic light-emitting device, there is a technique of using a silver layer having excellent electron injection properties (see, for example, Patent Document 1). Further, in order to increase the light transmittance of the light emitted from the light-emitting layer, there is a technique of using a transparent conductive layer (for example, ITO) having excellent light transparency as a material for the main electrode (see, for example, Patent Document 2). Further, in an organic EL display device, the size is increasing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a silver layer is used as the cathode electrode of an organic light-emitting device, in order to increase the light transmission through the cathode electrode, it is necessary to form the silver layer with a thin thickness. However, if the silver layer is thinly formed by an evaporation method having an excellent thickness distribution even in large-area film formation, the silver layer may become island-shaped due to heat radiation from the evaporation source.

[0006] On the other hand, when a transparent conductive layer is used instead of a silver layer as the cathode electrode, the electron injection layer, which is the base layer of the transparent conductive layer, may be deteriorated by oxygen and water generated in the vacuum chamber when the transparent conductive layer is formed.

[0007] In view of the above circumstances, an object of the present invention is to provide a more reliable organic light-emitting device, a film-forming method for forming a more reliable organic light-emitting device, and a film-forming apparatus.

Means for Solving the Problems

[0008] To achieve the above object, an organic light-emitting device according to an aspect of the present invention includes a light-emitting layer, an electron injection layer, a hole injection layer, an electron transport layer, and a hole transport layer. The light-emitting layer is provided between a cathode layer and an anode layer. The electron injection layer is provided between the cathode layer and the light-emitting layer. The hole injection layer is provided between the anode layer and the light-emitting layer. The electron transport layer is provided between the electron injection layer and the light-emitting layer. The hole transport layer is provided between the hole injection layer and the light-emitting layer. The cathode layer is composed of a transparent conductive layer. The electron injection layer contains a first component including at least one of silver, aluminum, copper, gold, and platinum, and a second component including at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid. In the electron injection layer, the concentration of the first component is relatively higher than the concentration of the second component on the side of the transparent conductive layer.

[0009] With such an organic light-emitting device, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer, and a more reliable organic light-emitting device is provided.

[0010] In the above organic light-emitting device, in the above electron injection layer, the concentration of the second component is relatively higher than the concentration of the first component on the side of the electron transport layer, and from the side of the electron transport layer toward the side of the cathode layer, the concentration of the first component relative to the concentration of the second component may gradually increase.

[0011] For such an organic light-emitting device, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer, and a more reliable organic light-emitting device is provided.

[0012] Also, a metal layer composed of the first component may be provided between the electron injection layer and the cathode layer.

[0013] For such an organic light-emitting device, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer, and a more reliable organic light-emitting device is provided.

[0014] To achieve the above object, a film formation method according to one embodiment of the present invention is a film formation method for forming an electron injection layer on an electron transport layer included in an organic light-emitting device. As a film formation source, a first film formation source including at least one of silver, aluminum, copper, gold, and platinum, and a second film formation source including at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid are prepared. With the film formation source and the electron transport layer opposed to each other in a first direction, while relatively moving the electron transport layer and the film formation source in a second direction intersecting the first direction, when forming the electron injection layer with the components of the first film formation source and the components of the second film formation source, the first film formation source and the second film formation source are arranged in the second direction so that the second film formation source and the electron transport layer overlap earlier than the first film formation source in the first direction, and film formation is executed.

[0015] For such a film formation method, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer, and a more reliable organic light-emitting device is formed.

[0016] In the above-described film-forming method, the above-described film formation may be performed by sputtering film formation.

[0017] In such a film-forming method, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer by the sputtering method, and a more reliable organic light-emitting device is formed.

[0018] In the above-described film-forming method, after performing the above-described film formation to form the electron injection layer on the above-described electron transport layer, a transparent conductive layer as the cathode layer may be formed on the above-described electron injection layer.

[0019] In such a film-forming method, an organic light-emitting device having both an electron injection layer that is less likely to be deteriorated by the film formation of the cathode layer and a highly transparent cathode layer is formed.

[0020] In order to achieve the above object, a film-forming apparatus according to one embodiment of the present invention includes a substrate holder, a film-forming source, and a moving mechanism. The above-described substrate holder can support a substrate on which the electron transport layer included in the organic light-emitting device is exposed toward the film-forming source. The above-described film-forming source includes a first film-forming source that faces the above-described substrate holder in a first direction and includes at least one of silver, aluminum, copper, gold, and platinum, and a second film-forming source that includes at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid. The above-described moving mechanism relatively moves the above-described substrate and the above-described film-forming source in a second direction intersecting the above-described first direction. When relatively moving the above-described electron transport layer and the above-described film-forming source, the above-described first film-forming source and the above-described second film-forming source are arranged side by side in the above-described second direction such that the above-described second film-forming source and the above-described substrate overlap before the above-described first film-forming source in the above-described first direction.

[0021] In such a film-forming apparatus, the electron injection layer is less likely to be deteriorated by the film formation of the cathode layer, and a more reliable organic light-emitting device is formed.

[0022] In the above-described film-forming apparatus, a partition plate extending in the first direction may be provided between the first film-forming source and the second film-forming source.

[0023] In such a film-forming apparatus, the sputtering particles emitted from the first film-forming source are less likely to adhere to the target surface of the second film-forming source, and the sputtering particles emitted from the second film-forming source are less likely to adhere to the target surface of the first film-forming source, and stable discharge continues.

Advantages of the Invention

[0024] As described above, according to the present invention, a more reliable organic light-emitting element, a film-forming method for forming a more reliable organic light-emitting element, and a film-forming apparatus are provided.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, XYZ-axis coordinates may be introduced. Also, the same reference numerals may be given to the same members or members having the same function, and the description may be omitted as appropriate after the description of such members. Further, the numerical values shown below are examples and are not limited to this example.

[0027] FIG. 1(a) is a schematic cross-sectional view showing the organic light-emitting device of the present embodiment. In FIG. 1(a), as an example, the main part of the top emission type organic light-emitting device 1 is shown. FIG. 1(b) is a graph showing the concentration distribution of components contained in the electron injection layer of the organic light-emitting device.

[0028] The organic light-emitting device 1 includes a light-emitting layer (EML) 10, an electron transport layer (ETL) 21, a hole transport layer (HTL) 22, an electron injection layer (EIL) 31, a hole injection layer (HIL) 32, a cathode layer 41, and an anode layer 42. In the organic light-emitting device 1, the hole injection layer 32, the hole transport layer 22, the light-emitting layer 10, the electron transport layer 21, and the electron injection layer 31 are laminated in this order from the anode layer 42 toward the cathode layer 41.

[0029] The light-emitting layer 10 is provided between the cathode layer 41 and the anode layer 42. The electron injection layer 31 is provided between the cathode layer 41 and the light-emitting layer 10. The hole injection layer 32 is provided between the anode layer 42 and the light-emitting layer 10. The electron transport layer 21 is provided between the electron injection layer 31 and the light-emitting layer 10. The hole transport layer 22 is provided between the hole injection layer 32 and the light-emitting layer 10.

[0030] In the organic light-emitting device 1, light emitted from the light-emitting layer 10 is extracted from the cathode layer 41. On the opposite side of the cathode layer 41, that is, under the anode layer 42, a support substrate (not shown) for supporting the organic light-emitting device 1 is disposed. Circuits such as thin-film transistors and wirings, and interlayer insulating layers, etc. are disposed on the substrate (all not shown). The support substrate may be a flexible substrate or a non-flexible plate-shaped substrate.

[0031] The cathode layer 41 is composed of a transparent conductive layer. As the material of the transparent conductive layer, for example, a transparent conductive oxide (TCO: Transparent Conductive Oxide) is applied. For example, as the material of the transparent conductive layer, ITO (In2O3 - SnO2), IZO (In2O3 - ZnO), ITO - IZO, etc. can be mentioned.

[0032] The electron injection layer 31 contains a first component including at least one of silver and aluminum, and a second component including at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid. The first component is not limited to at least one of silver and aluminum, and may include at least one of silver, aluminum, copper, gold, and platinum. For example, the electron injection layer 31 includes at least one of Ag and Al, and at least one of LiF, CsF, NaF, Ca, Ba, and Yb. The thickness of the electron injection layer 31 is configured to be extremely thin in order to enhance light transmission, for example, 5 nm or more and 10 nm or less. For example, the distance from the position of the depth where the concentration of the first component exceeds the concentration of the second component (the intersection of the concentration gradient line of the second component and the concentration gradient line of the first component) to the interface B is at least 2.0 nm.

[0033] When a voltage is applied to the anode layer 42 and the cathode layer 41, holes are injected from the hole injection layer 32 into the hole transport layer 22, and electrons are injected from the electron injection layer 31 into the electron transport layer 21. Subsequently, the holes that have moved through the hole transport layer 22 and the electrons that have moved through the electron transport layer 21 recombine in the light - emitting layer 10, and light is generated in the light - emitting layer 10. The light generated in the light - emitting layer 10 is emitted from the light - emitting layer 10 to each side of the anode layer 42 and the cathode layer 41.

[0034] The organic light-emitting device 1 is a top emission type, and the hole injection layer 32, the hole transport layer 22, the light-emitting layer 10, the electron transport layer 21, the electron injection layer 31, and the cathode layer 41 are configured to have a high light transmittance with respect to the emitted light. Further, the anode layer 42 is configured to reflect the emitted light. Thereby, the light emitted from the light-emitting layer 10 directly toward the cathode layer 41 and the light emitted light bounced back by the anode layer 42 are combined, and the light emitted light in the organic light-emitting device 1 passes through the cathode layer 41 and is emitted to the outside of the organic light-emitting device 1. In particular, since the cathode layer 41 is not an ultrathin metal film but is composed of a transparent conductive oxide, in the organic light-emitting device 1, the cathode layer 41 has a high light transmittance.

[0035] Here, in the electron injection layer 31 which is the base of the cathode layer 41, on the side of the transparent conductive layer (cathode layer 41), the concentration (atomic %) of the first component is relatively higher than the concentration (atomic %) of the second component.

[0036] For example, FIG. 1(b) shows the relationship between the concentration of the first component and the concentration of the second component from the interface A between the electron transport layer 21 and the electron injection layer 31 to the interface B between the electron injection layer 31 and the cathode layer 41. As shown in FIG. 1(b), in the electron injection layer 31, the concentration of the second component is relatively higher than the concentration of the first component on the side of the electron transport layer 21, and the concentration of the first component is relatively higher than the concentration of the second component on the side of the cathode layer 41. For example, from the side of the electron transport layer 21 toward the side of the cathode layer 41, the concentration of the first component with respect to the concentration of the second component gradually increases. For example, the element of the first component (for example, Ag element) is solid-solved with the second component in the electron injection layer 31.

[0037] Note that FIG. 1(b) shows a linear function of the first order as the concentration of the first component or the second component with respect to the depth, but the concentration of the first component with respect to the concentration of the second component may increase as a linear function of the nth order or may increase stepwise from the side of the electron transport layer 21 toward the side of the cathode layer 41.

[0038] A method for manufacturing the electron injection layer 31 having such a concentration distribution will be described. FIG. 2 is a schematic cross-sectional view of a main part of a film forming apparatus in which the film forming method of the present embodiment is executed. FIG. 2 shows a film forming apparatus 100 for forming an electron injection layer 31 on an electron transport layer 21 included in the organic light emitting element 1. In FIG. 2, during film formation, the direction in which the film forming source 60 and the substrate 91 or the substrate holder 90 face each other is defined as the Z-axis direction (first direction). Further, the direction in which the substrate 91 and the film forming source 60 relatively move is defined as the Y-axis direction (second direction). The first direction and the second direction intersect (for example, are orthogonal).

[0039] The film forming apparatus 100 includes a substrate holder 90, a film forming source 60, a moving mechanism 70, and a sputtering shield 95. The substrate holder 90 is capable of supporting the substrate 91. On the film forming surface of the substrate 91, a laminate 50 on which a light emitting layer 10, an electron transport layer 21, a hole transport layer 22, a hole injection layer 32, and an anode layer 42 of the organic light emitting element 1 are already formed is provided.

[0040] During film formation, the substrate 91 is not shielded by the sputtering shield 95 from the film forming source 60, and the sputtering shield 95 is exposed through an opening 96 that is interrupted in the Y-axis direction. In the substrate 91, the electron transport layer 21 included in the organic light emitting element 1 is exposed toward the film forming source 60. The electron transport layer 21 may be exposed from a mask pattern (not shown).

[0041] The film forming source 60 includes a first film forming source 61 and a second film forming source 62. For example, the first film forming source 61 is a sputtering target containing at least one of silver, aluminum, copper, gold, and platinum. The second film forming source 62 is a sputtering target containing at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid.

[0042] The sputtering targets of the first film-forming source 61 and the second film-forming source 62 are planar targets. The first film-forming source 61 and the second film-forming source 62 extend in the X-axis direction that intersects (for example, is orthogonal to) the Z-axis direction and the Y-axis direction. That is, the sputtering target has a longitudinal direction in the X-axis direction. In the sputtering target, the surface facing the substrate 91 is the sputtering surface.

[0043] Also, a magnet mechanism 67 is provided behind each of the sputtering targets on the side opposite to the sputtering surface. Thereby, in the film-forming apparatus 100, magnetron sputtering film formation becomes possible. The magnet mechanism 67 swings in the Y-axis direction behind the sputtering target. Each of the first film-forming source 61 and the second film-forming source 62 is supplied with discharge power independently from a power source (not shown).

[0044] In the film-forming apparatus 100, when the electron transport layer 21 formed on the substrate 91 and the film-forming source 60 move relative to each other, the first film-forming source 61 and the second film-forming source 62 are arranged side by side in the Y-axis direction such that the second film-forming source 62 and the substrate 91 overlap with each other before the first film-forming source 61 in the Z-axis direction. A partition plate 65 extending in the Z-axis direction is provided between the first film-forming source 61 and the second film-forming source 62. The partition plate 65 also extends in the X-axis direction. The partition plate 65 has a longitudinal direction in the X-axis direction.

[0045] The moving mechanism 70 relatively moves the substrate 91 and the film-forming source 60 in the Y-axis direction (second direction) that intersects the Z-axis direction. For example, the moving mechanism 70 relatively moves the substrate 91 and the film-forming source 60 in the Y-axis direction orthogonal to the Z-axis direction. For example, the substrate holder 90 and the anti-deposition plate 95 are fixed, and the film-forming source 60 moves in the scanning direction. It should be noted that the film-forming source 60 may be fixed under the opening 96, and the substrate holder 90 and the substrate holder 90 may move in the Y-axis direction.

[0046] Figs. 3(a) to 3(c) are schematic cross-sectional views showing the film-forming method of the present embodiment.

[0047] When attempting to form an electron injection layer 31 on the electron transport layer 21 included in the organic light-emitting element 1, for example, sputtering film formation using a binary film formation source is performed. For example, as a film formation source 60, a first film formation source 61 and a second film formation source 62 are prepared. Note that the scanning of the film formation source 60 in sputtering film formation is set to one pass in one direction. The substrate 91 is, for example, a large substrate of 1.5 m to 3.0 m (Y-axis direction) and 1.5 m to 3.5 m (X-axis direction). An electron transport layer 21 is formed on the outermost surface of the substrate 91 facing the film formation source 60.

[0048] In the film formation method of the present embodiment, the film formation source 60 and the electron transport layer 21 are opposed in the Z-axis direction, and discharge power is supplied to both the first film formation source 61 and the second film formation source 62. Then, while relatively moving the electron transport layer 21 and the film formation source 60 in the Y-axis direction, the components of the first film formation source 61 and the components of the second film formation source 62 are formed on the electron transport layer 21.

[0049] For example, as shown in FIG. 3(a), in the film formation source 60, when the film formation source 60 is moved in the scanning direction, the first film formation source 61 and the second film formation source 62 are arranged so that the second film formation source 62 and the electron transport layer 21 overlap earlier than the first film formation source 61 in the Z-axis direction.

[0050] As a result, at an arbitrary position P1 on the substrate 91, sputtering particles 62s emitted from the second film formation source 62 at the beginning of film formation are preferentially deposited on the electron transport layer 21. Also, in the middle stage of film formation, as shown in FIG. 3(b), sputtering particles 62s emitted from the second film formation source 62 and sputtering particles 61s emitted from the first film formation source 61 are deposited on the electron transport layer 21. Then, in the final stage of film formation, as shown in FIG. 3(c), sputtering particles 61s emitted from the first film formation source 61 are preferentially formed on the electron transport layer 21. As a result, an electron injection layer 31 having the concentration distribution shown in FIG. 1(b) is formed on the electron transport layer 21.

[0051] As the discharge gas, Ar gas is used. The discharge power is 0.5 W / cm for the first film formation source 61 2 ~10 W / cm 2 and 0.5 W / cm for the second film formation source 622 ~10 W / cm 2 It is. The discharge power may be DC power, pulsed DC power, or AC power (RF, VHF, etc.). The film formation pressure is 0.2 Pa to 3.0 Pa. The distance (T / S) between the substrate and the film formation source is 9 cm to 30 cm. The target length (the length of the target in the X-axis direction) is 180 cm to 350 cm. The scanning speed is 200 cm / min to 1000 cm / min. The film formation speed on the substrate 91 by the first film formation source 61 or the second film formation source 62 is 10 nm / second to 100 nm / second. The film formation temperature is 25°C to 80°C. The film formation speed may be set to the same film formation speed or different film formation speeds in the first film formation source 61 and the second film formation source 62.

[0052] After the film formation of the electron injection layer 31 is performed and the electron injection layer 31 is formed on the electron transport layer 21, a transparent conductive layer as the cathode layer 41 is formed on the electron injection layer 31. The film formation conditions of the transparent conductive layer are shown below. Thereby, the organic light-emitting element 1 is formed. The film formation conditions shown below are an example and are appropriately changed according to the configuration of the film formation apparatus.

[0053] Film formation source: ITO-IZO target Discharge power: 0.5 W / cm 2 ~5.0 W / cm 2 (DC discharge) Discharge gas: Ar / O2 Film formation pressure: 0.2 Pa to 3.0 Pa Film formation temperature: 25°C to 80°C

[0054] In the organic light-emitting element 1, in order to lower the energy barrier for electrons at the interface between the electron transport layer 21 and the electron injection layer 31, as the material of the electron injection layer 31, a material (second component) containing at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid is used. Also, in the organic light-emitting element 1, a transparent conductive layer is used as the cathode layer 41 in order to enhance the light transmission of the light emitted from the cathode layer 41.

[0055] However, the second component such as an alkali metal is easily oxidized by trace amounts of oxygen, water, etc. Therefore, when forming a transparent conductive layer on the electron injection layer 31 using a sputtering target containing the material of the transparent conductive layer, the electron injection layer 31 may deteriorate due to oxygen contained in the film formation atmosphere during film formation or trace amounts of water remaining in the vacuum chamber.

[0056] On the other hand, in this embodiment, the electron injection layer 31 serving as the base of the transparent conductive layer has the concentration distribution shown in Fig. 1(b). Therefore, when forming a transparent conductive layer on the electron injection layer 31, even if the electron injection layer 31 is exposed to oxygen and water, Ag or Al, which is the first component, serves as a barrier against oxygen and water, suppressing the deterioration of the electron injection layer 31.

[0057] Also, in this embodiment, the electron injection layer 31 is formed by a sputtering method instead of a vapor deposition method using a crucible. As a result, during film formation, the electron injection layer 31 is less likely to be affected by heat radiation from the crucible. For example, if the electron injection layer 31 is affected by heat radiation from the crucible during film formation, migration of the first component is promoted on the electron transport layer 21, and there is a possibility that the first component becomes locally particulate by sintering in the electron injection layer 31.

[0058] In this embodiment, the electron injection layer 31 is formed by a sputtering method instead of a vapor deposition method using a crucible. Therefore, during film formation, the electron injection layer 31 is less likely to be affected by heat radiation from the film formation source, suppressing migration of the first component on the electron transport layer 21. As a result, in the electron injection layer 31, the first component is less likely to become locally particulate, and the first component and the second component are solid-solubilized with each other.

[0059] As a result, the organic light-emitting element 1 has both a cathode layer 41 with excellent light transmittance and an electron injection layer 31 that does not deteriorate even when attempting to form the cathode layer 41 (transparent conductive layer) on the electron injection layer 31, improving the reliability of the organic light-emitting element.

[0060] In addition, in this embodiment, the first film-forming source 61 and the second film-forming source 62 are partitioned by a partition plate 65. Therefore, during film formation, the sputtering particles 61s emitted from the first film-forming source 61 are less likely to adhere to the target surface of the second film-forming source 62, and the sputtering particles 62s emitted from the second film-forming source 62 are less likely to adhere to the target surface of the first film-forming source 61.

[0061] As a result, during film formation, plasma discharge is stabilized on the target surfaces of the first film-forming source 61 and the second film-forming source 62, and the emission amounts of the sputtering particles of the first film-forming source 61 and the second film-forming source 62 per unit time are stabilized.

[0062] (Modification 1) FIG. 4(a) is a schematic cross-sectional view showing an organic light-emitting device according to Modification 1 of this embodiment. FIG. 4(b) is a graph showing the concentration distribution of components contained in the layer between the cathode layer and the electron transport layer according to Modification 1.

[0063] In the organic light-emitting device 2, a metal layer 35 made of a first component is provided between the electron injection layer 31 and the cathode layer 41. The metal layer 35 is formed, for example, by a sputtering method. The thickness of the metal layer 35 is at least 2.0 nm and is set to 2.0 nm to 10 nm. Since the metal layer 35 is formed by a sputtering method, it is less likely to become particulate compared to the case of forming by an evaporation method, and a uniform layer is formed between the electron injection layer 31 and the cathode layer 41.

[0064] For example, the organic light-emitting device 2 is formed by applying discharge power only to the first film-forming source 61 and further scanning the first film-forming source 61 once after the electron injection layer 31 is formed by the film-forming method illustrated in FIGS. 3(a) to 3(c).

[0065] In such an organic light-emitting device 2, when the cathode layer 41 is formed, since the electron injection layer 31 is covered by the metal layer 35, the electron injection layer 31 is less likely to deteriorate. As a result, the reliability of the organic light-emitting device 2 is further improved.

[0066] (Modification Example 2) FIG. 5(a) is a schematic cross-sectional view showing an organic light-emitting device according to Modification Example 2 of the present embodiment. FIG. 5(b) is a graph showing the concentration distribution of components contained in the layer between the cathode layer and the electron transport layer according to Modification Example 2.

[0067] In the organic light-emitting device 3, a metal layer 35 made of a first component is provided between the electron injection layer 31 and the cathode layer 41. Further, the electron injection layer is an electron injection layer 310 made of a second component. The thickness of the metal layer 35 is at least 2.0 nm and is set to 2.0 nm to 10 nm.

[0068] For example, the organic light-emitting device 3 is formed by applying discharge power only to the second film-forming source 62, scanning the second film-forming source 62, and then applying discharge power only to the first film-forming source 61 and scanning the first film-forming source 61 one more time.

[0069] Even with such a configuration, when the cathode layer 41 is formed, since the electron injection layer 310 is covered by the metal layer 35, the electron injection layer 310 is less likely to deteriorate. As a result, the reliability of the organic light-emitting device 3 is further improved.

[0070] FIG. 6 is a graph showing an example of the relationship between the incident energy of oxygen in the plasma when the cathode layer is sputter-deposited with a silver film or an aluminum film and the depth at which oxygen penetrates into the silver film or the aluminum film. The horizontal axis represents the incident energy of oxygen (eV), and the vertical axis represents the depth at which oxygen penetrates into the silver film or the aluminum film. In the graph, Ag means the case of a silver film, and Al means the case of an aluminum film.

[0071] As shown in FIG. 6, it has been found that at an incident energy of oxygen of 600 eV, which is the maximum on the horizontal axis, oxygen penetrates 1.4 nm into the silver film. In other words, with this level of incident energy, oxygen does not penetrate more than 1.4 nm into the silver film. That is, it has been found that if a layer containing Ag or the like exists at least 1.4 nm or more under the cathode layer 41, the electron injection layer is less likely to be deteriorated by oxygen.

[0072] Also, it has been found that oxygen penetrates 2.0 nm into the Al film at 600 eV where the incident energy of oxygen is maximum on the horizontal axis. In other words, with this level of incident energy, oxygen does not penetrate more than 2.0 nm into the Al film. That is, it has been found that if a layer containing Al or the like exists at least 2.0 nm or more under the cathode layer 41, the electron injection layer is less likely to be deteriorated by oxygen.

[0073] As described above, the embodiments of the present invention have been explained, but the present invention is not limited only to the above-described embodiments, and it goes without saying that various modifications can be made. Each embodiment is not necessarily an independent form, and can be combined as much as technically possible.

Explanation of Reference Numerals

[0074] 1, 2, 3... Organic light-emitting element 10... Light-emitting layer 21... Electron transport layer 22... Hole transport layer 31, 310... Electron injection layer 32... Hole injection layer 35... Metal layer 41... Cathode layer 42... Anode layer 50... Laminate 60... Film-forming source 61... First film-forming source 62... Second film-forming source 61s, 62s... Sputtering particles 65... Partition plate 67... Magnet mechanism 70... Moving mechanism 90... Substrate holder 91... Substrate 95... Anti-deposition plate 96... Opening 100... Film-forming apparatus

Claims

1. a light-emitting layer provided between a cathode layer and an anode layer; an electron injection layer provided between the cathode layer and the light-emitting layer; a hole injection layer provided between the anode layer and the light-emitting layer; an electron transport layer provided between the electron injection layer and the light-emitting layer; a hole transport layer provided between the hole injection layer and the light-emitting layer and comprising; the cathode layer is composed of a transparent conductive layer; the electron injection layer a first component containing at least one of silver, aluminum, copper, gold, and platinum; a second component containing at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid and containing; from the side of the electron transport layer toward the side of the cathode layer, the concentration of the first component with respect to the concentration of the second component gradually increases; in the electron injection layer, the concentration of the first component is relatively high compared to the concentration of the second component on the side of the transparent conductive layer, and the concentration of the second component is relatively high compared to the concentration of the first component on the side of the electron transport layer an organic light-emitting device.

2. The organic light-emitting device according to claim 1, wherein a metal layer composed of the first component is provided between the electron injection layer and the cathode layer an organic light-emitting device.

3. A film-forming method for forming an electron injection layer on an electron transport layer included in an organic light-emitting device by a sputtering method, wherein as a film-forming source, a first film-forming source having a sputtering target composed of a first component containing at least one of silver, aluminum, copper, gold, and platinum and a second film-forming source having a sputtering target composed of a second component containing at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid are prepared; The film-forming source and the electron transport layer are opposed to each other in a first direction, and while relatively moving the electron transport layer and the film-forming source in a second direction intersecting the first direction, when forming the electron injection layer from components of the first film-forming source and components of the second film-forming source, a partition plate is provided between the first film-forming source and the second film-forming source, which extends in the first direction and prevents adhesion of sputtering particles emitted from the first film-forming source to the target surface of the second film-forming source and adhesion of sputtering particles emitted from the second film-forming source to the target surface of the first film-forming source. By arranging the first film-forming source and the second film-forming source side by side in the second direction so that the second film-forming source and the electron transport layer overlap with each other ahead of the first film-forming source in the first direction, the concentration of the first component gradually increases with respect to the concentration of the second component from the side of the electron transport layer toward the surface side of the electron injection layer, which is the opposite side thereof, and on the surface side of the electron injection layer, the concentration of the first component is made relatively higher than the concentration of the second component, and on the side of the electron transport layer, the concentration of the second component is made relatively higher than the concentration of the first component. Film-forming method.

4. The film-forming method according to claim 3, after forming the electron injection layer on the electron transport layer by performing the film formation, a transparent conductive layer as a cathode layer is formed on the electron injection layer. Film-forming method.

5. a substrate holder capable of supporting a substrate on which an electron transport layer included in an organic light-emitting element is exposed toward a film-forming source, a first film-forming source facing the substrate holder in a first direction and having a sputtering target made of a first component including at least one of silver, aluminum, copper, gold, and platinum, and a second film-forming source having a sputtering target made of a second component including at least one of an alkali metal, an alkaline earth metal, a fluoride of an alkali metal, a fluoride of an alkaline earth metal, and a lanthanoid, which is a film-forming source for forming an electron injection layer on the electron transport layer, a moving mechanism for relatively moving the substrate and the film-forming source in a second direction intersecting the first direction, a partition plate provided between the first film-forming source and the second film-forming source, which extends in the first direction and prevents adhesion of sputtering particles emitted from the first film-forming source to the target surface of the second film-forming source and adhesion of sputtering particles emitted from the second film-forming source to the target surface of the first film-forming source comprising When forming the electron injection layer while relatively moving the electron transport layer and the film-forming source, the first film-forming source and the second film-forming source are arranged side by side in the second direction such that the second film-forming source and the substrate overlap prior to the first film-forming source in the first direction The concentration of the first component gradually increases with respect to the concentration of the second component from the side of the electron transport layer toward the surface side of the electron injection layer, which is the opposite side thereof. On the surface side of the electron injection layer, the concentration of the first component is made relatively higher than the concentration of the second component, and on the side of the electron transport layer, the concentration of the second component is made relatively higher than the concentration of the first component film-forming apparatus

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