JP2010263030A - Organic el device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device which prolongs the lifetime while reducing the drive voltage. <P>SOLUTION: The organic EL device 10 includes an anode, a cathode (Al layer 17), and an organic layer 20 which is arranged between the anode and the cathode and includes a light emission layer. At least the organic layer 20 side of the anode consists of a translucent oxide semiconductor layer (an ITO layer 12). A molybdenum dioxide layer 13 is arranged between the oxide semiconductor layer and the organic layer 20. Assuming that the molybdenum dioxide layer 13 is a layer of uniform thickness, thickness of the molybdenum dioxide layer 13 is 2 nm or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL element.

  Organic EL devices have attracted a great deal of attention because they can produce displays and light sources that have the advantages of flexibility, thinness, and light weight. However, the organic EL element still has many problems, and in order to develop its utilization, further improvement in characteristics is required.

As one method for improving the characteristics of the organic EL device, a method of inserting a hole injection layer at the interface between the anode and the hole transport layer is known. It has been reported that the characteristics can be improved by using a MoO ₃ layer as the hole injection layer (Patent Documents 1 and 2, Non-Patent Documents 1 to 5). However, the MoO ₃ layer which has been generally used conventionally, the thickness is in the range of 2 to 50 nm.

  The invention described in Patent Document 2 is intended to increase the luminance and save power of the organic EL element. Patent Document 2 discloses a top emission type organic EL element that emits light on the side opposite to the substrate. In this organic EL element, an anode made of aluminum, an organic layer, and a cathode made of ITO are formed on a substrate in this order. Light generated in the organic layer is emitted outside through the cathode. A Mo oxide layer (thickness is, for example, 3.5 to 1000 angstroms) is disposed between the anode and the organic layer. When the anode of the top emission type organic EL element includes a transparent electrode such as ITO, light traveling from the light emitting layer toward the anode is transmitted twice through the transparent electrode before being emitted to the outside. Therefore, Patent Document 2 describes that when the anode of the top emission type organic EL element includes a transparent electrode such as ITO, light absorption by the transparent electrode becomes a problem ([0004 of Patent Document 2]. ] Paragraph). Further, Patent Document 2 describes that when ITO is used for the anode, there arises a problem that the current density decreases (paragraph [0005] of Patent Document 2).

Japanese Patent Laying-Open No. 2005-32618 JP 2006-344774 A

Tokyo et al. Phys. D: Appl. Phys. 29, 2750 (1996) Miyashita et al., Jpn. J. et al. Appl. Phys. 44, 3682 (2005) Chen et al., Appl. Phys. Lett. 87, 241121 (2005) Satoh et al., Jpn. J. et al. Appl. Phys. 45, 1829 (2006) You et al. Appl. Phys. 101, 026105 (2007)

  At present, reduction of power consumption and extension of device life are problems in organic EL devices. Under such circumstances, an object of the present invention is to provide an organic EL element capable of reducing the driving voltage and extending the lifetime.

  By disposing a very thin molybdenum dioxide layer between the light-transmitting oxide semiconductor layer (anode) and the organic layer, the present inventors have conventionally known the effect of the molybdenum oxide layer. Has found that a completely different and excellent effect can be obtained. The present invention is based on this new knowledge.

  In order to achieve the above object, a first organic EL element of the present invention is an organic EL element comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode and including a light emitting layer. And at least the organic layer side of the anode is made of a light-transmitting oxide semiconductor layer, a molybdenum dioxide layer is disposed between the oxide semiconductor layer and the organic layer, and the molybdenum dioxide layer is When it is assumed that the thickness is a uniform layer, the thickness of the molybdenum dioxide layer is 2 nm or less.

  The second organic EL element of the present invention is an organic EL element comprising an anode, a cathode, and an organic layer that is disposed between the anode and the cathode and includes a light emitting layer. At least the organic layer side is formed of a light-transmitting oxide semiconductor layer, and the oxide semiconductor layer and the organic layer are not in contact with the interface between the oxide semiconductor layer and the organic layer. A uniformly formed molybdenum dioxide layer is arranged.

  ADVANTAGE OF THE INVENTION According to this invention, the organic EL element which can reduce a drive voltage and prolong a lifetime is obtained.

It is a figure which shows typically the structure of the organic EL element produced in the Example. It is a figure which shows the structure of (alpha) -NPD used in the Example. It is a graph which shows the relationship between the virtual thickness of a molybdenum dioxide layer, and a drive voltage. It is a graph which shows the relationship between the virtual thickness of a molybdenum dioxide layer, and energy conversion efficiency. It is a graph which shows the relationship between the virtual thickness of molybdenum dioxide, and the maintenance factor of a brightness | luminance. It is a graph showing the relationship between the virtual thickness and drive time T ₉₀ of molybdenum dioxide.

  Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments and examples. In the following description, specific numerical values and specific materials may be exemplified, but other numerical values and other materials may be applied as long as the effect of the present invention is obtained.

[Organic EL device]
Hereinafter, matters common to the first and second organic EL elements of the present invention will be described. The organic EL device of the present invention includes an anode, a cathode, and an organic layer. The organic layer is disposed between the anode and the cathode and includes a light emitting layer. At least the organic layer side of the anode is made of a light-transmitting oxide semiconductor layer. A molybdenum dioxide layer is disposed between the oxide semiconductor layer and the organic layer. That is, the organic EL element of the present invention has a laminated structure of oxide semiconductor layer / molybdenum dioxide layer / organic layer. Note that in a typical example, the molybdenum dioxide layer is formed non-uniformly, and the oxide semiconductor layer and the organic layer are in partial contact at the interface between the oxide semiconductor layer and the organic layer.

  Preferable examples of the oxide semiconductor include ITO (Indium Tin Oxide), zinc oxide added with aluminum (AZO), and zinc oxide added with indium (IZO). A film formed of these materials is sometimes called a transparent conductive film. Among these, ITO is preferable because good characteristics can be obtained.

  The anode is an electrode for injecting holes. The anode may be formed of only an oxide semiconductor layer. A typical example of the anode is made of only ITO, zinc oxide added with aluminum (AZO), or zinc oxide added with indium (IZO). However, the anode may be formed of a multilayer film. For example, an anode including a metal layer such as aluminum and an oxide semiconductor layer (AZO layer, IZO layer, or ITO layer) formed thereon may be used.

  The organic layer is a layer substantially composed of an organic compound. However, an inorganic compound (such as a dopant) may be added to the organic layer.

  The organic layer may include other layers in addition to the light emitting layer. For example, the organic layer may include at least one layer selected from a hole transport layer, an electron transport layer, and an electron injection layer. Although the molybdenum dioxide layer is considered to function as a hole injection layer, the organic EL device of the present invention may include another hole injection layer in addition to the molybdenum dioxide layer as long as the effects of the present invention are obtained. These layers are laminated in the order of anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode. Note that layers other than the anode (including the oxide semiconductor layer), the cathode, and the light-emitting layer can be omitted depending on circumstances. These may be laminated on a substrate (for example, a transparent substrate, for example, a glass substrate) in order from the anode side, or may be laminated in order from the cathode side. As long as the effect of the present invention can be obtained, the material of these layers is not particularly limited, and for example, a known organic material can be used.

  When light generated in the light emitting layer is emitted from the substrate side, a substrate made of a light-transmitting material is used as the substrate. For example, a glass substrate or a resin substrate such as a polyimide substrate can be used. In the case where light generated in the light emitting layer is emitted from the side opposite to the substrate side, the substrate may or may not be translucent.

An aromatic amine derivative can be used as the material for the hole transport layer. For example, triphenylamine derivatives (TPD, α-NPD, β-NPD, MeO-TPD, TAPC), phenylamine tetramer (TPTE), starburst triphenylamine derivatives (m-MTDADA, NATA, 1-TNATA 2-TNATA), spiro-type triphenylamine derivatives (Spiro-TPD, Spiro-NPD, Spiro-TAD), rubrene, pentacene, copper phthalocyanine (CuPc), titanium oxide phthalocyanine (TiOPc), alpha-sexithiophene (α −6T) can be used. Examples of the material for the light emitting layer include an aluminoquinolinol complex (Alq ₃ ), a carbazole derivative (MCP, CBP, TCTA), a triphenylsilyl derivative (UGH2, UGH3), an iridium complex (Ir (ppy) ₃ , Ir (ppy) ₂ (acac), FIrPic, Fir6, Ir (piq) ₃ , Ir (btp) ₂ (acac)), rubrene, coumarin derivatives (Coumarin6, C545T), quinacridone derivatives (DMQA), pyran derivatives (DCJTB), europium complexes ( Eu (dbm) ₃ (phen)). Examples of the material for the electron transport layer include quinolinol complexes (Alq ₃ , BAlq, Liq), oxadiazole derivatives (OXD-7, PBD), triazole derivatives (TAZ), phenanthroline derivatives (BCP, BPhen), and phosphorus oxide derivatives. (POPy ₂ ) and triazine derivatives (TRZ, DPT, MPT). An example of the material for the electron injection layer made of an organic compound is lithium phenanthridionate (Liph). These materials are selected and combined in consideration of their characteristics. Note that one compound may be a material for a layer having different functions in elements having different structures. For example, Alq ₃ may be a material for the light emitting layer, may be a material for the electron transport layer, or may be a material for a layer that serves as both the light emitting layer and the electron transport layer.

The organic EL element of the present invention may include an inorganic layer made of an inorganic material. The inorganic layer may be disposed between the layers constituting the organic layer, or may be disposed between the organic layer and the electrode (anode and / or cathode). For example, the electron injection layer may be a layer made of an inorganic material. Examples of the inorganic material that can be used for the electron injection layer include lithium, cesium, barium, calcium, sodium, magnesium, lithium fluoride, cesium fluoride, lithium oxide, and cesium carbonate (Cs ₂ CO ₃ ).

  The cathode is an electrode for injecting electrons. As the material of the cathode, a conductive material can be used, and examples thereof include metals such as aluminum, silver, neodymium-aluminum alloy, gold-aluminum alloy, and magnesium-silver alloy. The cathode may be formed of a multilayer film.

  In a typical example of the present invention, light generated in the light emitting layer is emitted from the anode side. However, as long as the effect of the present invention is obtained, the light generated in the light emitting layer may be emitted from the cathode side. In that case, the cathode is formed of a light-transmitting conductive material (for example, the above-described oxide semiconductor or thin metal electrode).

  In an example of the organic EL element of the present invention, the layer adjacent to the anode (the layer closest to the anode) in the organic layer is a hole transport layer. In that case, the molybdenum dioxide layer is disposed between the anode and the hole transport layer. In another example of the organic EL device of the present invention, the layer adjacent to the anode in the organic layer is a light emitting layer. In that case, the molybdenum dioxide layer is disposed between the anode and the light emitting layer. In an example of the organic EL element of the present invention, the organic layer includes a hole transport layer adjacent to the anode, and the hole transport layer is made of α-NPD. That is, in the example, the layer closest to the anode among the layers included in the organic layer is made of α-NPD. The layer closest to the anode among the layers included in the organic layer may be any one selected from the group consisting of α-NPD, TPD, 2-TNATA, α-6T, and CuPc. It may be composed of at least one selected from the group consisting of them. Particularly preferred materials for the hole transport layer in combination with molybdenum dioxide are α-NPD, TPD, and 2-TNATA.

In one example, the molybdenum dioxide layer is made of molybdenum dioxide whose composition formula is represented by MoO ₂ . However, when a molybdenum dioxide layer is formed by a vapor deposition method using molybdenum dioxide (MoO ₂ ) as a raw material, the proportion of oxygen may be lower than the above composition formula. Even in that case, since the formed layer is generally called a molybdenum dioxide layer, in this specification, a layer made of molybdenum oxide whose composition formula is represented by MoO _x (x ≦ 2), for example, A layer made of molybdenum oxide that becomes 2 when x is rounded off is called a molybdenum dioxide layer. In a typical example, molybdenum dioxide layer of the present invention consists of two molybdenum oxide composition formula is represented by _{MoO 2 (1.5 ≦ x ≦ 2} ).

The molybdenum dioxide layer can be formed, for example, by a vapor deposition method such as a vacuum deposition method using MoO ₂ as a deposition source or a sputtering method. In the case of forming the molybdenum dioxide layer by vacuum deposition to a MoO ₂ deposition source, the oxygen concentration of the molybdenum dioxide layer formed reduced than the oxygen concentration of the deposition source (MoO _2), Table above MoO _x A molybdenum dioxide layer may be formed.

[Method of manufacturing organic EL element]
There is no limitation in the manufacturing method of the organic EL element of this invention, For example, you may manufacture by a well-known method. The organic layer and the inorganic layer may be formed by a vapor deposition method such as a vacuum deposition method or a sputtering method. The organic layer may be formed by applying a solution containing an organic material.

[Molybdenum dioxide layer in the first organic EL element]
The first organic EL element of the present invention is characterized in that the molybdenum dioxide layer has a thickness of 2 nm or less when the molybdenum dioxide layer is assumed to be a uniform layer. Hereinafter, the thickness of the molybdenum dioxide layer when the molybdenum dioxide layer is assumed to be a uniform layer may be referred to as a “virtual thickness”. The virtual thickness may be 0.1 nm or more, 0.25 nm or more, and may be less than 2 nm, 1.5 nm or less, 1 nm or less, or 0.5 nm or less. For example, the virtual thickness may be in the range of 0.25 nm to 1 nm or in the range of 0.25 nm to 0.5 nm.

  By disposing the molybdenum dioxide layer between the oxide semiconductor layer and the organic layer, the driving voltage can be reduced and the life can be extended. However, by setting the virtual thickness of the molybdenum dioxide layer to 2 nm or less, Long life is possible. The effect of extending the life due to the molybdenum dioxide layer becomes significant when the virtual thickness of the molybdenum dioxide layer is 1 nm or less (for example, 0.25 nm to 1 nm), and is 0.5 nm or less (for example, 0.25 nm to 0.5 nm). This is particularly noticeable.

  The molybdenum dioxide layer may be formed by, for example, a vapor deposition method such as a vapor deposition method or a sputtering method. It may be difficult to form a molybdenum dioxide layer while measuring its thickness. Therefore, when a molybdenum dioxide layer is formed by a vapor deposition method, the film formation rate is measured in advance, the time for film formation is calculated from the film formation rate, and the film is formed only for that time. The thickness of the molybdenum dioxide layer may be controlled. In the embodiment, the thickness of the molybdenum dioxide layer estimated by this method is defined as “virtual thickness”.

  In the first organic EL element of the present invention, a molybdenum dioxide layer is formed at the interface between the oxide semiconductor layer and the organic layer. The molybdenum dioxide layer may be formed non-uniformly at the interface between the oxide semiconductor layer and the organic layer so that the oxide semiconductor layer and the organic layer are in partial contact. An example of a state in which the molybdenum dioxide layer is formed unevenly will be described in the description of the second organic EL element.

[Molybdenum dioxide layer in second organic EL element]
In the second organic EL device of the present invention, a molybdenum dioxide layer that is non-uniformly formed so that the oxide semiconductor layer and the organic layer are in partial contact with each other is disposed at the interface between the oxide semiconductor layer and the organic layer. It is characterized by being.

  In the second organic EL element, a molybdenum dioxide layer is unevenly formed at the interface between the oxide semiconductor layer and the organic layer. That is, in the second organic EL element, the molybdenum dioxide layer is not formed on the entire interface between the oxide semiconductor layer and the organic layer, but only on a part of the interface. The molybdenum dioxide layer may be formed in an island shape at the interface between the oxide semiconductor layer and the organic layer (the surface of the oxide semiconductor layer). Further, the portion where the molybdenum dioxide layer is formed and the portion where the molybdenum dioxide layer is not formed may be formed so as to be mottled.

  In the second organic EL element, it is preferable that the portion where the molybdenum dioxide layer is formed is uniformly dispersed. For example, when a region of 10 μm square (preferably 0.5 μm square) is arbitrarily selected at the interface between the oxide semiconductor layer and the organic layer, the region where the molybdenum dioxide layer is formed and the molybdenum dioxide layer are formed. It is preferable that these regions are uniformly dispersed so that the regions are not necessarily included.

  Since the molybdenum dioxide layer is formed unevenly, its thickness is not constant. However, the thickness of the molybdenum dioxide layer (the “imaginary thickness”) is 2 nm or less when it is assumed that the molybdenum dioxide layer having a non-uniform thickness is leveled into a uniform thickness layer. The virtual thickness may be 0.1 nm or more, 0.25 nm or more, and may be less than 2 nm, 1.5 nm or less, 1 nm or less, or 0.5 nm or less. For example, the virtual thickness may be in the range of 0.25 nm to 1 nm or in the range of 0.25 nm to 0.5 nm.

  In the second organic EL element, it is important that the molybdenum dioxide layer is not formed on the entire surface of the anode. Although the details are not clear at present, it is thought that an unexpected effect can be obtained by the molybdenum dioxide layer being scattered on the surface of the anode. Therefore, it is considered important to form a very thin molybdenum dioxide layer so that the molybdenum dioxide layer does not become a uniform film.

  In the production of the second organic EL element, the method for forming the molybdenum dioxide layer is not particularly limited as long as the molybdenum dioxide layer can be formed unevenly. The molybdenum dioxide layer may be formed by, for example, a vapor deposition method such as a vapor deposition method or a sputtering method. When a thin layer (for example, 1 nm or less in thickness) is formed by a vacuum evaporation method, it is considered that a non-uniform layer is formed.

In the examples, organic EL elements were produced and their characteristics were evaluated. The structure of the produced organic EL element 10 is schematically shown in FIG. The organic EL element 10 includes a glass substrate 11, an ITO layer 12 (thickness 150 nm), a molybdenum dioxide layer 13, an α-NPD layer 14 (thickness 60 nm), an Alq ₃ layer 15 (thickness 65 nm), and a LiF layer 16 (thickness). 0.5 nm), and an Al layer 17 (thickness 100 nm). In FIG. 1, the molybdenum dioxide layer 13 is schematically shown as a layer having a uniform thickness.

alpha-NPD layer 14 and the Alq ₃ layer 15, the organic layer 20. The molybdenum dioxide layer 13 is disposed between the ITO layer 12 (anode) and the α-NPD layer 14 functioning as a hole transport layer. Alq ₃ (aluminoquinolinol complex) was used as the material of the light emitting layer. The light generated in the light emitting layer was emitted to the outside of the device through the ITO layer 12 and the glass substrate 11. In the organic EL element 10, α-NPD was used as the material of the organic layer adjacent to the molybdenum dioxide layer 13. The structure of α-NPD is shown in FIG.

The organic layer was formed by a vacuum deposition method at a pressure of 1 × 10 ⁻⁴ to 4 × 10 ⁻⁴ Pa. The inorganic layer (including the MoO ₂ layer) was formed by a vacuum deposition method at a pressure of 1 × 10 ^{−3 to} 3 × 10 ⁻³ Pa. The molybdenum dioxide layer was formed by a vacuum evaporation method using MoO ₂ powder as a material.

  The deposition rate of the molybdenum dioxide layer was 0.05 nm / second. The deposition rate of the molybdenum dioxide layer was obtained in advance by forming a thick film for measuring the deposition rate.

  The thickness of the molybdenum dioxide layer was changed in the range of 0 nm to 10 nm. Here, the “thickness of the molybdenum dioxide layer” is the above-mentioned “virtual thickness”, and the thickness when the molybdenum dioxide layer is assumed to be a uniform layer without unevenness. It is. For example, the molybdenum dioxide layer having a virtual thickness of 0.25 nm was formed by operating the shutter of the vapor deposition apparatus so that the molybdenum dioxide layer was deposited on the ITO layer for 5 seconds. Since the deposition rate of molybdenum dioxide was 0.05 nm / second, assuming that a layer having a uniform thickness and no unevenness was formed, the thickness was 0.25 nm. Actually, a layer having a uniform thickness is not formed, and it is considered that a region where the molybdenum dioxide layer is formed and a region where the molybdenum dioxide layer is not formed exist on the ITO layer. Assuming smoothing, the thickness is 0.25 nm. However, it is considered that the molybdenum dioxide layer is formed almost uniformly without gaps when the thickness exceeds a certain level.

About the produced organic EL element, the drive voltage when an element was driven with the current density of 50 mA / cm < ² > was measured. FIG. 3 shows the relationship between the virtual thickness of the molybdenum dioxide layer and the driving voltage. FIG. 3 shows that the virtual thickness of the molybdenum dioxide layer is 0 nm (no molybdenum dioxide layer), 0.25 nm, 0.5 nm, 0.75 nm, 1.0 nm, 1.5 nm, 2.0 nm, 5 nm, and 10 nm. The result of the case is shown. As shown in FIG. 3, the drive voltage was greatly reduced by forming a molybdenum dioxide layer having a virtual thickness of 0.25 nm or more.

About the produced organic EL element, the energy conversion efficiency when driving an element with the current density of 50 mA / cm < ² > was calculated | required. FIG. 4 shows the relationship between the virtual thickness of the molybdenum dioxide layer and the energy conversion efficiency. In FIG. 4, the hypothetical thickness of the molybdenum dioxide layer is 0 nm (no molybdenum dioxide layer), 0.25 nm, 0.5 nm, 0.75 nm, 1.0 nm, 1.5 nm, 2.0 nm, 5 nm, and 10 nm. The result of the case is shown.

  As shown in FIG. 4, the energy conversion efficiency was improved by using the molybdenum dioxide layer. This is considered to be because the drive voltage was reduced. The energy conversion efficiency was particularly high when the virtual thickness of the molybdenum dioxide layer was in the range of 0.25 nm to 5 nm.

The organic EL device produced was driven at a constant current of 50 mA / cm ^2, were evaluated life characteristics. FIG. 5 shows the evaluation results when the virtual thickness of the molybdenum dioxide layer is 0 nm, 0.25 nm, 0.5 nm, 0.75 nm, 1.0 nm, 1.5 nm, 2.0 nm, 5.0 nm, and 10 nm. The horizontal axis in FIG. 5 indicates the drive time. The vertical axis represents the luminance maintenance rate with respect to the initial luminance. The device having a virtual thickness of 0.75 nm showed the same process as the device having a virtual thickness of 1.0 nm. In addition, the device having a virtual thickness of 1.5 nm showed the same progress as the device having a virtual thickness of 2.0 nm. In addition, the device having the virtual thickness of 5.0 nm showed the same progress as the device having the virtual thickness of 10 nm.

FIG. 6 shows the relationship between the driving time until the luminance reaches 90% of the initial luminance (hereinafter sometimes referred to as “driving time T ₉₀ ”) and the virtual thickness of the molybdenum dioxide layer. FIG. 6 shows the results when the virtual thickness of the molybdenum dioxide layer is 0 nm, 0.25 nm, 0.5 nm, 0.75 nm, 1.0 nm, 1.5 nm, 2.0 nm, 5.0 nm, and 10 nm. Show. The relation between the virtual thickness and drive time T ₉₀ of the molybdenum dioxide layer in Table 1.

Under the conditions evaluated, the drive time _T90 was increased by forming the molybdenum dioxide layer. Driving time T _90, the virtual thickness of the molybdenum dioxide layer is increased by the following cases 2.0 nm, made longer if: 1.0 nm, was particularly long in the case of 0.5nm or less. Drive time T _90, the virtual thickness becomes longest in the case of 0.25 nm. When the virtual thickness of the molybdenum dioxide layer was 2.0 nm or less, the driving time _T90 was about three times or more compared with the case where the molybdenum dioxide layer was not formed. Further, when the virtual thickness of the molybdenum dioxide layer is in the range of 0.25 nm to 2.0 nm, the driving time T ₉₀ is 1.5 times or more compared to the case where the virtual thickness of the molybdenum dioxide layer is 10 nm. We were able to. Further, when the virtual thickness of the molybdenum dioxide layer is in the range of 0.25 nm to 0.5 nm, the driving time T ₉₀ should be doubled or more compared to the case where the virtual thickness of the molybdenum dioxide layer is 10 nm. I was able to.

  Although the embodiments of the present invention have been described above by way of examples, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

  The present invention can be applied to an organic EL element. The organic EL element of the present invention can reduce the driving voltage and extend the life as compared with the conventional organic EL element. Extending the life of organic EL elements has been a long-standing issue for organic EL elements, and the present invention has a great influence on industries that use organic EL elements. The present invention is preferably used for, for example, a display panel using an organic EL element.

10 Organic EL element 11 glass substrate 12 ITO layer 13 of molybdenum dioxide layer 14 alpha-NPD layer 15 Alq ₃ layer 16 LiF layer 17 Al layer 20 organic layer

Claims (5)

An organic EL device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode and including a light emitting layer,
At least the organic layer side of the anode is made of a light-transmitting oxide semiconductor layer,
A molybdenum dioxide layer is disposed between the oxide semiconductor layer and the organic layer;
An organic EL element in which the molybdenum dioxide layer has a thickness of 2 nm or less when the molybdenum dioxide layer is assumed to be a uniform layer.   The organic EL element according to claim 1, wherein the oxide semiconductor layer is an ITO layer.   The organic EL element according to claim 1 or 2, wherein the molybdenum dioxide layer has a thickness in the range of 0.25 nm to 0.5 nm when the molybdenum dioxide layer is assumed to be a uniform layer. An organic EL device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode and including a light emitting layer,
At least the organic layer side of the anode is made of a light-transmitting oxide semiconductor layer,
An organic EL element in which a molybdenum dioxide layer formed non-uniformly so that the oxide semiconductor layer and the organic layer are in partial contact with each other is disposed at an interface between the oxide semiconductor layer and the organic layer .   The organic EL element according to claim 4, wherein the oxide semiconductor layer is an ITO layer.