JP2005123205A - Organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a need in a top emission type organic EL element to form in a negative electrode a transparent electrode of a metal oxide, such as ITO requiring high-temperature annealing which adversely influences organic layer, and eliminate disadvantages caused by the formation of the transparent electrode of a metal oxide. <P>SOLUTION: The organic EL element 10 has on a substrate 11 a sequential lamination of a positive electrode 12, the organic layer 13 including at least an emission layer 17, and the negative electrode 14, and emits light from the emission layer 17 from the opposite side to the substrate 11. The organic layer 17 includes an emission layer containing a fluorescent dopant, and an emission layer containing a phosphorescent dopant. The fluorescent dopant including emission layer is laminated nearer to the negative electrode than to the phosphorescent dopant including emission layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic EL (electroluminescence) element, and more particularly to an organic EL element having a cathode as a transparent electrode.

  In general, in an organic EL element, a transparent electrode (anode) made of ITO (indium tin oxide) is formed on a glass substrate, an organic layer including a light emitting layer is formed on the transparent electrode, and an opaque cathode Is formed by laminating the light emitting layers, and the light emitted from the light emitting layer is extracted from the glass substrate side. Such an element is called a bottom emission type element. In the bottom emission type organic EL element, the cathode is provided on the side opposite to the light extraction side with respect to the light emitting layer, and therefore it is not necessary to be particularly transparent. Generally, lithium, magnesium, calcium, aluminum, etc. Metals with relatively small work functions, metal oxides, and metal alloys are used.

  In such a bottom emission type organic EL element, a conventional technique with an improved cathode has been proposed. For example, a conventional technique is proposed in which the cathode has a two-layer structure of an alloy layer containing 6 mol% or more of alkali metal and a 50 nm or more non-corrosive metal cathode layer containing no alkali metal element thereon. (For example, see Patent Document 1).

  Further, an alloy region having a thickness of 5 to 50 nm containing 0.5 to 5 at% of an alkali metal or an alkaline earth metal having a work function of 2.9 eV or less as a cathode in a total amount of the alkali metal and the alkaline earth metal; There has also been proposed a structure in which two regions including an upper metal region having a thickness of 50 to 300 nm and made of a metal having a work function of 3.0 eV or more are provided (see, for example, Patent Document 2). In this prior art, the alloy region and the upper metal region are sequentially formed so that the alloy region is on the organic layer side, and the concentration of oxygen in the cathode is 1 at% or less.

  On the other hand, a top emission type organic EL element that extracts light emitted from the light emitting layer from the side opposite to the glass substrate has also been proposed (see, for example, Patent Document 3). The organic EL element described in Patent Document 3 uses a metal electrode for the anode, and the cathode is an extremely thin (0.5 to 20 nm film thickness) electron injection metal layer, and a transparent conductive layer (200 nm film thickness In—Zn). -O-based transparent conductive film).

  When organic EL elements are used as display devices, there are a passive matrix method and an active matrix method as driving methods. The active matrix method is often more advantageous for organic EL elements. For example, as compared with the passive matrix system, the actual luminance may be lower in order to obtain the same luminance per unit time.

  On the other hand, it is also required to provide a transparent cathode other than the ITO electrode when the cathode is a transparent electrode, regardless of whether it is a bottom emission type or a top emission type.

JP-A-4-212287 (paragraphs [0022] to [0043] in FIG. 1, FIG. 1) Japanese Patent Laid-Open No. 9-232079 (paragraphs [0011] to [0029] of the specification) JP 2001-43980 A (paragraphs [0014] to [0015] in FIG. 1, FIG. 1)

  As a result of diligent efforts, the present inventors have found an organic EL element having a novel transparent cathode.

  The first organic EL element found by the present inventors is an organic EL element in which an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially laminated on a substrate. The organic layer includes a light emitting layer containing a fluorescent dopant and a light emitting layer containing a phosphorescent dopant. And the light emitting layer containing the said fluorescent dopant is laminated | stacked on the cathode side rather than the light emitting layer containing the said phosphorescence dopant.

  The second organic EL device found by the inventors of the present application is that an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially stacked on a substrate, and the light emission of the light emitting layer is different from that of the substrate. It is an organic EL element taken out from the opposite side. The organic layer includes a light emitting layer containing a fluorescent dopant and a light emitting layer containing a phosphorescent dopant. And the light emitting layer containing the said fluorescent dopant is laminated | stacked on the cathode side rather than the light emitting layer containing the said phosphorescence dopant.

In such an organic EL device of the present invention, the fluorescent dopant is preferably a blue fluorescent dopant. The phosphorescent dopant is preferably at least one of a red phosphorescent dopant and a green phosphorescent dopant. Moreover, it is also preferable that the light emitting layer containing the said phosphorescent dopant contains a red phosphorescent dopant and a green phosphorescent dopant.
Moreover, it is preferable that the light emitting layer containing the said phosphorescent dopant consists of a light emitting layer containing a red phosphorescent dopant, and a light emitting layer containing a green phosphorescent dopant.
Further, it is preferable to further provide a hole block layer adjacent to the cathode side of the light emitting layer containing the fluorescent dopant.
The cathode covers an electron injection layer formed transparently using a metal, a metal alloy, or a metal compound, and a surface of the electron injection layer opposite to the surface facing the organic layer. It is made of ITO (indium tin oxide) made of a metal or metal alloy that plays a role of protection, and the cathode has the same resistance value and the same shape as the cathode. The transparent electrode is preferably formed to have a resistance value or less.

  As is clear from the above description, the inventors of the present application have found an organic EL element having a novel configuration including a novel transparent cathode.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic cross-sectional view of an organic EL element.

  As shown in FIG. 1, the organic EL element 10 is formed by sequentially laminating an anode 12, an organic layer 13 including at least a light emitting layer, and a cathode 14 on a substrate 11. The substrate 11 is made of a transparent glass substrate, and a metal anode 12 is formed thereon (in FIG. 1, the upper surface of the substrate 11). The anode 12 has reflectivity for visible light. The cathode 14 is formed transparent. That is, the organic EL element 10 is a top emission type organic EL element in which light emission of the light emitting layer is extracted from the side opposite to the substrate 11.

The anode 12 is formed of chromium by sputtering and formed to a thickness of, for example, 200 nm, and then patterned by etching using a photolithography process.
On the anode 12, an organic layer 13 composed of a hole injection layer 15, a hole transport layer 16, and a light emitting layer 17 is laminated and formed in this order from the anode 12 side. In this embodiment, the hole injection layer 15 is made of copper phthalocyanine (CuPc) and is formed to be a layer having a thickness of 10 nm. The hole transport layer 16 is made of a tetraphenylamine tetramer (TPTE) having a methyl group at the meta position of the terminal phenyl, and is formed to be a 10 nm thick layer. The light emitting layer 17 is made of an organic light emitting material such as tris (8-quinolinol) aluminum (Alq3), which is an aluminum complex of an 8-quinolinol derivative, and is formed to be a 65 nm thick layer. The hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 are all formed by vapor deposition at a pressure of 5 × 10 ⁻⁵ Pa or less.

  The cathode 14 covers the surface opposite to the surface of the electron injection layer 18 that faces the organic layer 13 of the electron injection layer 18 that is transparently formed of a metal, metal alloy, or metal compound, and protects the electron injection layer 18. It is comprised from the coating layer 19 formed transparently by the metal or metal alloy which plays a role. In this embodiment, both the electron injection layer 18 and the coating layer 19 are formed of a very thin metal layer and are transparent. Transparent means that the visible light transmittance is 50% or more. Further, “very thin” means 50 nm or less. The cathode 14 is formed so that its resistance value is equal to or less than the resistance value of the ITO transparent electrode formed in the same position and at the same position as the cathode 14.

In this embodiment, the electron injection layer 18 is formed of alkaline earth metal calcium (Ca), and the coating layer 19 is formed of silver (Ag). The electron injection layer 18 and the coating layer 19 are also formed by vapor deposition at a pressure of 5 × 10 ⁻⁵ Pa or less. That is, the organic EL element 10 of this embodiment is formed by vapor deposition from the hole injection layer 15 to the coating layer 19 that are sequentially laminated on the anode 12.

  When the electron injection layer 18 is formed of calcium, the film thickness is preferably in the range of 5 to 50 nm. If it is this range, the transmittance | permeability will become larger than 50% and sheet resistance will not become so large. When the coating layer 19 is formed of silver, the film thickness is 5 to 20 nm, preferably 7 to 11 nm. If it is thinner than 5 nm, it is difficult to form a good layer, and if it is thicker than 20 nm, the visible light transmittance is insufficient. When the film thickness is in the range of 7 to 11 nm, the transmittance of the coating layer 19 is greater than 50%, and the sheet resistance is not so large.

  The work function of calcium forming the electron injection layer 18 is 2.9 eV, and the lowest unoccupied molecular orbital (LUMO) level of Alq3 constituting the light emitting layer 17 as an organic layer adjacent to the electron injection layer 18 is about − 3.1 eV. That is, in this embodiment, the work function of the metal (calcium) forming the electron injection layer 18 is equal to or less than the absolute value of the LUMO level of the adjacent organic layer (light emitting layer 17). Further, since silver is an element having the lowest resistivity among metal elements, the covering layer 19 is formed of a material having a resistivity lower than that of the metal forming the electron injection layer 18.

  The coating layer 19 is a layer that prevents deterioration of the electron injection layer 18 such as oxidation. A material suitable for the electron injection layer 18 is generally highly reactive. When the cathode 14 is composed of only the electron injection layer 18, deterioration such as oxidation tends to proceed. However, the provision of the coating layer 19 suppresses the deterioration.

  In the organic EL element 10, the anode 12, the organic layer 13, and the cathode 14 are exposed to the electrode extraction side portions of the anode 12 and the cathode 14 (both not shown), and the organic layer 13 is not in contact with the outside air. Thus, it is sealed with a glass cover (not shown).

Next, a method for manufacturing the organic EL element 10 configured as described above will be described.
When manufacturing the organic EL element 10, first, the anode 12 is formed on the substrate 11. The anode 12 is formed by depositing chromium on the substrate 11 with a film thickness of 200 nm by sputtering. Next, patterning is performed by etching in a photolithography process.

Next, the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 constituting the organic layer 13 are sequentially formed by vapor deposition at a pressure of 5 × 10 ⁻⁵ Pa or less so as to have a predetermined film thickness. Next, the electron injection layer 18 and the covering layer 19 constituting the cathode 14 are sequentially formed by vapor deposition at a pressure of 5 × 10 ⁻⁵ Pa or less in the same manner as in the formation of the organic layer 13. To do. That is, each layer constituting the organic layer 13 and the cathode 14 is formed in the same vapor deposition apparatus. Finally, the anode 12, the organic layer 13, and the cathode 14 are sealed with a glass cover. The operation of attaching the glass cover to the substrate 11 is performed, for example, in a nitrogen gas atmosphere.

Next, the operation of the organic EL element 10 configured as described above will be described.
When a DC voltage is applied between the anode 12 and the cathode 14 of the organic EL element 10, holes are injected from the anode 12 into the hole transport layer 16 through the hole injection layer 15 and injected into the hole transport layer 16. The formed holes are transported to the light emitting layer 17 by the TPTE of the hole transport layer 16. On the other hand, electrons are injected from the electron injection layer 18 constituting the cathode 14 into the light emitting layer 17. Then, holes and electrons are recombined in the light emitting layer 17, the organic light emitting material is excited, and light is emitted when the material returns to the ground state.

  The cathode 14 has a two-layer structure of an electron injection layer 18 and a covering layer 19, and both layers are formed of a metal layer and are transparent. Therefore, it is not necessary to form a transparent electrode made of a metal oxide such as ITO on the cathode 14, and problems caused by the formation of the transparent electrode made of the metal oxide can be eliminated.

The organic EL element 10 (Example 1) configured as described above, and the anode 12 of the organic EL element 10 are changed to an ITO layer having a thickness of 200 nm, and the cathode 14 is changed to an aluminum layer having a thickness of 150 nm. With respect to the organic EL element having the same configuration (Comparative Example 1) except that the mold was used, the emission characteristics were measured at 11 mA / cm ² . The results are shown in Table 1.

  As shown in Table 1, the organic EL element 10 of Example 1 was slightly lower in applied voltage than the organic EL element of Comparative Example 1, and was excellent in terms of luminance, power efficiency, and current efficiency. Therefore, even if the cathode 14 is made of metal and the film thickness is made extremely thin in order to provide transparency, light emission at the same level or higher with an applied voltage equal to or lower than that of a conventional bottom emission type organic EL device. It was confirmed that the organic EL element 10 having characteristics was obtained.

As described above, in the organic EL element 10 according to the present embodiment, the cathode 14 disposed on the light extraction side is formed on the electron injection layer 18 formed of metal and transparent, and the organic layer 13 of the electron injection layer 18. A covering layer 19 that covers a surface opposite to the opposite surface and is transparently formed of a metal that serves to protect the electron injection layer 18; and the resistance value of the cathode 14 is the same as that of the cathode 14. It is formed so as to be equal to or less than the resistance value of the transparent electrode made of ITO formed in the same position.
The organic EL element configured as described above has the following effects.

(1) A transparent cathode can be formed by a vapor deposition method.
Since the electron injection layer 18 and the coating layer 19 are thin, and productivity is not greatly reduced even when film formation is performed by vapor deposition, it is not necessary to form a film by sputtering or the like. Therefore, a large amount of heat is not applied to the organic layer 13 when the transparent cathode is formed, and the possibility of causing damage such as deterioration or alteration to the organic layer 13 when forming the transparent cathode can be extremely reduced.

(2) Annealing is unnecessary.
This is because, as described above, the transparent cathode according to the present embodiment can obtain a practically sufficient resistivity without performing annealing. Therefore, the organic layer is not damaged by performing the annealing process as in the prior art.

(3) It is not necessary to provide a layer (damage prevention layer) for preventing damage to the organic layer 13 when forming the transparent cathode.
This is because the possibility of damaging the organic layer 13 when forming the transparent cathode is extremely low as described above. As a result, the organic layer 13 is not deteriorated at the time of forming the damage preventing layer, the transmittance is not lowered due to the presence of the damage preventing layer, and the conventional organic EL is not provided because this layer is not provided. It is also possible to make it thinner than the element.

  As is clear from the above (1) to (3), by adopting the transparent cathode according to the present embodiment, the cathode can be formed by a vapor deposition method, so that the organic layer 13 is not deteriorated during the production of the cathode or the like. I'm sorry.

(4) The light emission efficiency in the light emitting layer 17 can be increased.
This is because the work function of the material forming the electron injection layer 18 is equal to or lower than the LUMO level of the adjacent organic layer 13, so that electrons are injected well from the electron injection layer 18 into the organic layer 13.

(5) The efficiency of electron injection into the organic layer can be increased.
Since the material for forming the electron injection layer 18 is an alkaline earth metal, the electron injection efficiency is higher than when the electron injection layer 18 is formed of a metal other than an alkali metal and an alkaline earth metal.

(6) The transmittance can be increased.
Since calcium is used as a material for forming the electron injection layer 18, the transmittance of the electron injection layer 18 is improved as compared with other metals, and as a result, brightness is improved.

(7) The resistance of the cathode 14 as a whole can be lowered.
Since the coating layer 19 is made of a material having a resistivity lower than that of the electron injection layer 18, the resistance of the cathode 14 as a whole can be lowered by making the coating layer 19 thicker than the electron injection layer 18.
Therefore, as compared with the configuration in which the electron injection layer 18 is formed thicker than the coating layer 19, the protective effect of the electron injection layer 18 in which deterioration such as oxidation easily proceeds is improved.

(8) The applied voltage required when driving the organic EL element 10 can be lowered.
This is because the material of the covering layer 19 is silver. That is, as the material of the coating layer 19, silver having the lowest resistivity is used. Therefore, as long as the coating layer 19 has the same film thickness as compared to the case of using another metal, the organic EL The applied voltage required when driving the element 10 can be lowered.
When the applied voltage is the same, the thickness of the coating layer 19 can be reduced, the transmittance of the entire cathode 14 can be increased, and the light emission efficiency of the light emitting layer 17 can be increased.

(9) Effects such as productivity improvement can be obtained as compared with the conventional case.
Since calcium, which is the material of the electron injection layer 18, and silver, which is the material of the coating layer 19, are both easy to form by vapor deposition, the cathode 14 can be formed consistently from the organic layer 13 by the same vapor deposition apparatus. Because it can.
Further, after the organic layer 13 is formed, the intermediate product does not need to be transported to another apparatus to form the cathode 14, and environmental particles may adhere to the surface of the organic layer 13 during transport. Because there is no.

  Next, a second embodiment according to the present invention will be described.

(Second Embodiment)
In this embodiment, the configuration of the organic layer is different from that of the first embodiment, and the other configurations are the same. The same parts as those in the above embodiment are given the same reference numerals, and detailed description thereof is omitted.
As shown in FIG. 2, the organic EL element 20 is formed by sequentially laminating an anode 12, an organic layer 21, and a cathode 14 on a substrate 11.
The organic layer 21 includes five layers including a hole injection layer 15, a hole transport layer 16, a first light emitting layer 22a, a second light emitting layer 22b, and a third light emitting layer 22c. It is laminated on the hole transport layer 16. The light emitting layer 22 includes a first light emitting layer 22 a as a red light emitting layer, a second light emitting layer 22 b as a blue light emitting layer, and a third light emitting layer 22 c as a green light emitting layer, which are sequentially stacked on the hole transport layer 16. Thus, a white light emitting layer is formed.

  The first light emitting layer 22a is formed to a thickness of 5 nm using TPTE as a host and DCJT as a dopant. DCJT is contained at 0.5 wt% with respect to TPTE. DCJT is represented by the following chemical formula (1).

  The second light emitting layer 22b uses 4,4-bis (2,2-diphenyl-ethen-1-yl) -biphenyl (DPVBi) as a host and 4,4 ′-(bis (9-ethyl-3-carbazovinylene). -1,1′-biphenyl (BCzVBi) is used as a dopant to form a film thickness of 30 nm, and BCzVBi is contained at 5.0 wt% with respect to DPVBi.

  The third light emitting layer 22c uses Alq3 as a host and 10- (2-benzothiazolyl) -2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H- [1] benzopyrano. [6,7,8-ij] quinolizin-11-one (C545T) is used as a dopant to form a film with a thickness of 20 nm. C545T is contained at 1.0 wt% with respect to Alq3.

  The organic EL element 20 of this embodiment is formed in the same manner as the organic EL element 10 of the above-described embodiment, after the metal anode 12 is formed on the substrate 11, and then the organic EL element 20 and the cathode 14 are sequentially formed by vapor deposition. Is done.

Except that the organic EL element 20 (Example 2) configured as described above and the anode 12 of the organic EL element 20 were changed to an ITO layer having a thickness of 200 nm and the cathode 14 was changed to an aluminum layer having a thickness of 200 nm, respectively. The emission characteristics of the organic EL element having the same configuration (Comparative Example 2) were measured at 11 mA / cm ² . The results are shown in Table 2.

  As shown in Table 2, the applied voltage of the organic EL element 20 of Example 2 was slightly higher than that of the organic EL element of Comparative Example 2, but was excellent in terms of luminance, power efficiency, and current efficiency. Therefore, it was confirmed that even when the configuration of the light emitting layer was changed, the organic EL device 20 having a light emission characteristic equivalent to or higher than that of the conventional organic EL device having the bottom emission type configuration was obtained.

This embodiment has the following effects in addition to the same effects as (1) to (9) of the first embodiment.
(10) It can be used for a full-color display device.
Since the light emitting layer 22 emits white light, it can be used as the display device by combining the organic EL element 20 with a color filter.

The above-described organic EL element can obtain the above-described effects as long as it has at least the following conditions, and has the same or better performance than the conventional top emission type organic EL element having a transparent cathode made of ITO. Can be provided.
(I) A top emission type structure in which an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially formed on a substrate, and light emitted from the light emitting layer is extracted from the side opposite to the substrate, The cathode is composed of an electron injection layer and a coating layer, and has the following requirements.
The electron injection layer is formed transparently using a metal, a metal alloy, or a metal compound as a material. Note that the term “transparent” means that it is sufficient to be transparent with respect to the light extracted outside the element, and the light transmittance is at least 50% or more.
The covering layer is a layer formed transparently from a metal or metal alloy, and covers the surface opposite to the surface facing the organic layer in the electron injection layer, and is a layer for protecting the electron injection layer from the outside. is there.
The resistance value of the cathode is set to be equal to or less than the resistance value of the transparent electrode formed of ITO in the same shape and at the same position.

  Therefore, the organic EL element according to the present embodiment can be modified as follows, for example. Moreover, it is naturally possible to adopt a configuration in which the following modifications are appropriately combined.

-Modification of the material used for the electron injection layer 18 The electron injection layer 18 should just be transparently formed with the metal, the metal alloy, or the metal compound, but generally the metal and the metal alloy are more resistant than the metal compound. Since the rate is small, metals and metal alloys can be preferably employed from the viewpoint of resistance.

Examples of materials particularly suitable as a material for forming the electron injection layer 18 Among the materials as described above, the electron injection layer 18 includes, in particular, alkali metals (Li, Na, K, Rb, Cs) and alkaline earths. Metals (Ca, Ba, Sr, Ra) are preferably contained. That is, the electron injection layer 18 is preferably composed of an alkali metal, an alkaline earth metal, an alloy of these metals, or a metal compound containing these metals. Desirably, these metals are used. The reason is that these metals have a lower work function than other metals.
For example, the work functions (units eV) of easily available alkali metals and alkaline earth metals are Li: 2.93, K: 2.28, Cs: 1.95, and Ca: 2.9, which are easily available. The work functions (unit: eV) of other metals are Al: 4.28, Ag: 4.26, Cr: 4.5, Cu: 4.65, Mg: 3.36, Mo: 4.6. Therefore, these materials are particularly preferably employed.
Further, a metal compound having a small work function may be used as the material of the electron injection layer 18. Metal compounds have a large range of work function values. The work function (unit eV) of a metal compound having a relatively small work function is the following value, and the following materials are preferably employed.
NdC: 2.24-4.10
TaC: 3.05 to 3.98
ThO ₂ : 1.66 to 6.32
TiC: 2.35 to 4.09
ZrC: 2.18 to 4.22

Configuration example of the relationship between the material for forming the electron injection layer 18 and the adjacent organic layer 13 The material for forming the electron injection layer 18 has a work function equal to or less than the absolute value of the LUMO level of the adjacent organic layer 13. Preferably there is. Alkali metals and alkaline earth metals satisfy this condition.
Moreover, even if the organic layer has a laminated structure and the work function of the material forming the electron injection layer is set to be equal to or less than the absolute value of the LUMO level in the organic layer adjacent to the electron injection layer, a good organic EL element can be obtained. Can be provided.

A configuration example in which the electron injection layer 18 is made of a highly stable material The electron injection layer 18 may be an alloy. This is because a metal having a small work function is chemically unstable, and therefore, stability is often increased when used as an alloy rather than when used alone.

Configuration example in which the electron injection layer 18 is made of a material having a high electron injection property to the organic layer 13 When the electron injection layer 18 is made of a single metal, electron injection is performed more efficiently than the case of being made of an alloy. Because. Since the surface of the electron injection layer 18 is covered with the coating layer 19, even if the electron injection layer 18 is formed of a metal having a small work function, the electron injection layer 18 is protected by the coating layer 19.

Modification in which the electron injection layer 18 is not a completely uniform layer If the electron injection layer 18 is not necessarily formed on the entire surface of the organic layer 13, there is a pinhole or the like without forming a uniform layer. Also good. This is because the electron injection layer 18 is covered with the coating layer 19, so that even if there is a pinhole in the electron injection layer 18, there is no problem by forming the coating layer 19 in a uniform layer without pinholes.
In general, the coating layer is preferably 7 to 11 nm. If the film thickness is set to this level, the above-described effects can be obtained, and the pinholes in the electron injection layer 18 can be supplemented.
Further, the electron injection layer 18 may be formed in an island shape. That the electron injection layer is island-shaped means that the average film thickness of the electron injection layer 18 is equal to or less than the film thickness of the monomolecular film of the compound constituting this layer. When the electron injection layer 18 is composed of a plurality of compounds, the average film thickness may be equal to or less than the average value of the monomolecular film thickness of each compound.

Configuration Example in which Covering Layer 19 is Formed from a Material with a Resistivity that is Smaller than the Material for Forming Electron Injection Layer 18 Covering layer 19 is preferably formed from a material that has a smaller resistivity than the material that forms electron injection layer 18. When the resistivity of alkali metal and alkaline earth metal is compared, alkaline earth metal is smaller. For example, the resistivity of calcium is 3.91 × 10 ⁻⁶ Ωm, the resistivity of potassium is 6.15 × 10 ⁻⁶ Ωm, and the resistivity of lithium is 8.55 × 10 ⁻⁶ Ωm. As a stable metal having a small resistivity, silver (1.59 × 10 ⁻⁶ Ωm), copper (1.67 × 10 ⁻⁶ Ωm), aluminum (2.65 × 10 ⁻⁶ Ωm), gold (2. 35 × 10 ⁻⁶ Ωm) and the like.

Example of adopting the configuration of a known organic EL element The configurations of the organic layers 13 and 21 are the same as those in the first to second embodiments, the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17. The configuration of the known organic EL element is not limited to the configuration of the three types of 22 and can be appropriately employed.
For example, one of the hole injection layer 15 and the hole transport layer 16 may be eliminated or both may be eliminated. Further, a layer in which a hole injection material and a hole transport material are mixed may be provided between the anode 12 and the light emitting layers 17 and 22. Further, an electron transport layer may be provided between the light emitting layers 17 and 22 and the electron injection layer 18. It may be composed only of the light emitting layers 17 and 22.

More specifically, the organic layer can have a layer structure as follows, for example.
・ (Anode) / Hole injection layer / Hole transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole injection layer / Hole transport layer / Light emitting layer / Electron injection transport layer / (Cathode)
・ (Anode) / Hole injection / transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole injection / transport layer / Light emitting layer / Electron injection / transport layer / (Cathode)
・ (Anode) / Hole transport layer / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Hole transport layer / Light emitting layer / Electron injection transport layer / (Cathode)
・ (Anode) / Light emitting layer / Electron transport layer / Electron injection layer / (Cathode)
・ (Anode) / Light emitting layer / Electron injection / transport layer / (Cathode)
・ (Anode) / Light emitting layer / (Cathode)
Note that the electron injection layer in the organic layer in the above layer configuration example means a layer in which electrons are injected from the cathode in the organic layer, unlike the electron injection layer of the cathode in the present embodiment.

That is, the following functions required for the organic layer may be realized by a single layer or by a plurality of layers.
-Electron injection function Function to inject electrons from the electrode (cathode). Electron injection.
・ Hole injection function Function to inject holes from the electrode (anode). Hole injection property.
・ Carrier transport function Function to transport at least one of electrons and holes. Carrier transportability.
The function of transporting electrons is called an electron transport function (electron transportability), and the function of transporting holes is called a hole transport function (hole transportability).
-Luminescence function A function that emits light when returning to the ground state by recombining injected and transported electrons and carriers to generate excitons (in an excited state).

  Of course, other layers constituting a known organic layer may be provided.

An example of constituting an organic material employed in a known organic EL element Naturally, the organic material for forming the hole injection layer 15, the hole transport layer 16, and the light emitting layers 17 and 22 is the same as that of the first and second embodiments. It is not restricted to what was described in the form.
For example, instead of TPTE, the hole injection material may be a triphenylamine dimer (TPD) or a compound in which two phenyl groups of TPD are changed to naphthyl groups. Examples of the electron transporting material include a compound containing an oxadiazole or triazole structure or trinitrofluorenone (TNF). The light emitting material is not limited to the material in the above embodiment, and can be used.
In the following, an example in which the organic layer is composed of a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer will be described, and the case where other structures are employed will be described.

<Hole injection transport layer>
The hole injection transport layer is a layer provided between the anode 10 and the light emitting layer, and is a layer in which holes are injected from the anode 10 and the injected holes are transported to the light emitting layer. Generally, the ionization potential of the hole injection transport layer is set to be between the work function of the anode 10 and the ionization potential of the light emitting layer, and is usually set to 5.0 eV to 5.5 eV.
The organic EL element shown in FIG. 1 has the following properties by including a hole injecting and transporting layer.
・ Low drive voltage.
-Since the hole injection from the anode 10 to the light emitting layer is stabilized, the life of the device is extended.
-Since the adhesion between the cathode 10 and the light emitting layer is increased, the uniformity of the light emitting surface is increased.
-Element defects can be reduced by covering the protrusions of the anode 10 and the like.

  Further, when the hole injecting and transporting layer is provided closer to the light extraction side than the light emitting layer, it is formed transparent to the extracted light. A material that is transparent to the light when the film is thinned is appropriately selected from materials that can form the hole injecting and transporting layer. Generally, the transmittance for the extracted light is set to be larger than 10%. Is done.

  The material for forming the hole injecting and transporting layer is not particularly limited as long as it imparts the above properties to the hole injecting and transporting layer, and known materials that can be used as the hole injecting material for the photoconductive material, Any material can be selected and used from known materials used for the hole injection transport layer of the organic EL element.

  For example, phthalocyanine derivatives, triazole derivatives, triarylmethane derivatives, triarylamine derivatives, oxazole derivatives, oxadiazole derivatives, stilbene derivatives, pyrazoline derivatives, pyrazolone derivatives, polysilane derivatives, imidazole derivatives, phenylenediamine derivatives, amino-substituted chalcone derivatives, Styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, polyarylalkane derivatives, polyphenylene vinylene and its derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole derivatives, thiophene oligomers, etc. Conductive polymer oligomer, phthalocyanine derivative, carbazole derivative, quinacridone compound, aromatic Tertiary amine compounds, and the like styrylamine compound.

  Triarylamine derivatives include, for example, triphenylamine dimer to tetramer, 4,4′-bis [N-phenyl-N- (4 ″ -methylphenyl) amino] biphenyl, 4,4′- Bis [N-phenyl-N- (3 ″ -methylphenyl) amino] biphenyl, 4,4′-bis [N-phenyl-N- (3 ″ -methoxyphenyl) amino] biphenyl, 4,4′-bis [ N-phenyl-N- (1 ″ -naphthyl) amino] biphenyl, 3,3′-dimethyl-4,4′-bis [N-phenyl-N- (3 ″ -methylphenyl) amino] biphenyl, 1,1 -Bis [4 '-[N, N-di (4 "-methylphenyl) amino] phenyl] cyclohexane, 9,10-bis [N- (4'-methylphenyl) -N- (4" -n-butyl) Phenyl) amino] phena Tren, 3,8-bis (N, N-diphenylamino) -6-phenylphenanthridine, 4-methyl-N, N-bis [4 ", 4 '"-bis [N', N "- Di (4-methylphenyl) amino] biphenyl-4-yl] aniline, N, N ″ -bis [4- (diphenylamino) phenyl] -N, N′-diphenyl-1,3-diaminobenzene, N, N'-bis [4- (diphenylamino) phenyl] -N, N'-diphenyl-1,4-diaminobenzene, 5,5 "-bis [4- (bis [4-methylphenyl] amino) phenyl]- 2,2 ′: 5 ′, 2 ″ -terthiophene, 1,3,5-tris (diphenylamino) benzene, 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine, 4,4 ′, 4 "-Tris [N- (3 '' ' Methylphenyl) -N-phenylamino] triphenylamine, 4,4 ′, 4 ″ -tris [N, N-bis (4 ′ ″-tert-butylbiphenyl-4 ″ ″-yl) amino] triphenylamine 1,3,5-tris [N- (4′-diphenylaminophenyl) -N-phenylamino] benzene.

  Examples of porphyrin compounds include porphine, 1,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 1,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II). 5,10,15,20-tetrakis (pentafluorophenyl) -21H, 23H-porphine and the like.

  Examples of phthalocyanine derivatives include silicon phthalocyanine oxide, aluminum phthalocyanine chloride, phthalocyanine (metal free), dilithium phthalocyanine, copper tetramethylphthalocyanine, copper phthalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, copper Examples include octamethyl phthalocyanine.

  Examples of the aromatic tertiary amine compound and the styrylamine compound include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N′-bis. -(3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine, 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4- Di-p-tolylaminophenyl) cyclohexane, N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminophenyl, 1,1-bis (4-di-p-tolylaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N′-diphenyl-N, N′-di ( 4-me Xylphenyl) -4,4′-diaminobiphenyl, N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl ether, 4,4′-bis (diphenylamino) quadriphenyl, N, N , N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4 ′-[4 (di-p-tolylamino) styryl] stilbene, 4-N, N-diphenylamino- (2-diphenyl) Vinyl) benzene, 3-methoxy-4′-N, N-diphenylaminostilbenzene, N-phenylcarbazole and the like. Aromatic dimethylidin compounds can also be used as the material for the hole injecting and transporting layer 310.

Examples of the carbazole derivative include carbazole biphenyl and N-methyl-
N-phenylhydrazone-3-methylidene-9-ethylcarbazole, polyvinylcarbazole, Nisopropylcarbazole, Nphenylcarbazole and the like can be mentioned.

  The hole injecting and transporting layer may be formed from one of the materials as described above, or may be formed by mixing a plurality of materials. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

The hole injecting and transporting layer may be formed on the anode by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.
Although the film thickness depends on the material to be selected, it is usually 5 nm to 5 μm.

<Light emitting layer>
The light-emitting layer is mainly composed of an organic material, and holes and electrons are injected from the anode 10 side and the cathode side, respectively, and transports at least one of the holes and electrons to recombine them to form excitons (excitation). A layer that emits light when the exciton returns to the ground state.

Therefore, the material for forming the light emitting layer (organic material) only needs to have the following functions.
A hole injection function capable of injecting holes from the hole injection transport layer (or the anode 10).
An electron injection function that can inject electrons from the electron injection transport layer.
A transport function that moves at least one of injected holes and electrons by the force of an electric field.
A function that recombines electrons and holes to generate an excited state (exciton).
A function for generating light when returning from the excited state to the ground state.

Typical examples of the material having the above functions include Alq3 and Be-benzoquinolinol (BeBq2).
The following materials can also be used.

  2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) -1,3,4-thiadiazole, 4,4′-bis (5,7-benzyl-2-benzoxazolyl L) Stilbene, 4,4′-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-) Benzyl-2-benzoxazolyl) thiophine, 2,5-bis ([5-α, α-dimethylbenzyl] -2-benzoxazolyl) thiophene, 2,5-bis [5,7-di- ( 2-methyl-2-butyl) -2-benzoxazolyl] -3,4-diphenylthiophene, 2,5-bis (5-methyl-2-benzoxazolyl) thiophene, 4,4′-bis ( 2-Benzoxazolyl) biphenyl, 5-methyl-2- [2- [4 Benzoxazoles such as-(5-methyl-2-benzoxazolyl) phenyl] vinyl] benzoxazolyl, 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole; 2 , 2 ′-(p-phenylenedivinylene) -bisbenzothiazole and the like; 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyl) Phenyl) vinyl] benzimidazole and other fluorescent whitening agents,

Bis (8-quinolinol) magnesium, bis (benzo-8-quinolinol) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum 8-quinolinol lithium, tris (5-chloro-8-quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc-bis (8-hydroxy-5-quinolinyl) methane] Hydroxyquinoline-based metal complexes; metal chelated oxinoid compounds such as dilithium ependridione; 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis (4-methylstyryl) benzene, distyrylbenzene, 1,4- Styrylbenzene compounds such as s (2-ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene, 1,4-bis (2-methylstyryl) 2-methylbenzene; 2,5-bis ( 4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, Distil pyrazine derivatives such as 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine; naphthalimide derivatives; perylene derivatives; oxadiazole Derivatives; aldazine derivatives; cyclopentadiene derivatives; styrylamine derivatives; coumarin derivatives; aromatic dimethylidin derivatives; anthracene Salicylate; pyrene; coronene and,

Fac-tris (2-phenylpyridine) iridium, bis (2-phenylpyridinato-N, C2 ′) iridium (acetylacetonate), 6-di (fluorophenyl) -pyridinate-N, C2 ′) iridium (acetyl) Acetonato), iridium (III) bis [4,6-di (fluorophenyl) -pyridinate-N, C2 ′] picolinate, platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ') (2,4-pentaneconionate), platinum (II) (2- (4', 6'-difluorophenyl) pyridinate N, C2 ') (6-methyl-2,4-heptaneconate- O, O), bis (2- (2′-benzo [4,5-a] thienyl) pyridinate-platium (II) (2- (4 ′, 6′-difluorophenyl) pyridine N, C3 '), such as phosphorescent material such as iridium (acetylacetonate).

Further, the light emitting layer may contain a material (organic light emitting material / dopant) responsible for the electroluminescence generation function and a material (host material) responsible for other functions. In this case, the host material performs carrier injection and carrier transport, and is excited by recombination. The host material in an excited state moves excitation energy to the dopant. The dopant generates light when returning to the ground state. In addition, a mechanism in which the host material transports carriers to the dopant, performs recombination within the dopant, and generates light when the dopant returns to the ground state can be employed.
In general, a fluorescent material or a phosphorescent material is used as the dopant.

  The host material only needs to have the above functions, and a known material can be used. For example, distyrylarylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolato metal complexes, triarylamine derivatives, azomethine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, silole derivatives, naphthalene derivatives, anthracene derivatives, di Examples thereof include carbazole derivatives, perylene derivatives, oligothiophene derivatives, coumarin derivatives, pyrene derivatives, tetraphenylbutadiene derivatives, benzopyran derivatives, europium complexes, rubrene derivatives, quinacridone derivatives, triazole derivatives, benzoxazole derivatives, and benzothiazole derivatives.

  The fluorescent material is a fluorescent material (fluorescent dye, fluorescent dopant), and emits light from the singlet excited state at room temperature, which emits light when transitioning to the ground state by obtaining energy from the host material. Material. In addition, a material that emits light when returning to the ground state by recombining carriers transported from the host material at room temperature can be employed. In general, a material having high fluorescence quantum efficiency is selected, and the addition amount is 0.01 wt% or more and 20 wt% or less with respect to the host material.

  The fluorescent material may be appropriately selected from known materials having the above properties, for example, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, coumarin derivatives, europium complexes, rubrene derivatives, Nile Red 2- (1,1-dimethylethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolidine-9 -Yl) ethenyl) -4H-pyran-4H-ylidene) propanedinitrile (DCJTB), DCM, coumarin derivatives, quinacridone derivatives, distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives , Benzimidazole derivatives, chrysanthemum Derivatives, phenanthrene derivatives, distyryl benzene derivatives, tetraphenyl butadiene derivatives, rubrene derivatives, and the like.

  As a coumarin derivative, what is represented by the following general formula 1 can be mentioned, for example.

In General Formula 1, R ^{1 to} R ⁵ each independently represent a hydrogen atom or a hydrocarbon group, and the hydrocarbon group may have one or more substituents. The hydrocarbon group for R ^{1 to} R ⁵ is usually an aliphatic hydrocarbon group, preferably, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an isopropenyl group, a 1-propenyl group, or a 2-propenyl group. , Butyl group, isobutyl group, sec-butyl group, tert-butyl group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-pentenyl group, etc. Short chain long aliphatic hydrocarbon groups up to several 5, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclohexenyl group and other alicyclic hydrocarbon groups, phenyl group, o-tolyl group, m-tolyl group , P-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, biphenylyl Aromatic hydrocarbon group such as, more, a hydrocarbon group of these combinations thereof. One or more of the hydrogen atoms in the hydrocarbon group are, for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group , Ether groups such as isopentyloxy group, phenoxy group, benzyloxy group, acetoxy group, benzoyloxy group, ester group such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, fluoro group, chloro group, bromo group, iodo It may be substituted with a halogen group such as a group, or a substituent by a combination thereof. Although it depends on the use of the organic EL device, preferred is a coumarin derivative in which all of R ^{2 to} R ⁵ are aliphatic hydrocarbon groups, and in particular, a coumarin derivative in which R ^{2 to} R ⁵ are all methyl groups, It is particularly excellent in physical properties and economy.

R ^{6 to} R ¹³ in the general formula 1 each independently represent a hydrogen atom or a substituent. Examples of the substituent in R ^{6 to} R ¹³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, a butyl group, an isobutyl group, a sec-butyl group, tert-butyl group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, 2-pentenyl group, hexyl group , An isohexyl group, a 5-methylhexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an octadecyl group and the like, an aliphatic hydrocarbon group having up to 20 carbon atoms, a cyclopropyl group, a cyclobutyl group, Such as cyclopentyl, cyclohexyl, cyclohexenyl, cycloheptyl, etc. Cyclic hydrocarbon group, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, benzyl group, phenethyl group , Aromatic hydrocarbon group such as biphenylyl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, phenoxy group, benzyloxy group Ether groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, acetoxy group, benzoyloxy group and other ester groups, fluoro group, chloro group, bromo group, iodo group and other halogen groups, hydroxy group, carboxy group, Examples include cyano groups, nitro groups, and substituents based on combinations of these. It is done.

  More specifically, those represented by the following chemical formulas 1 to 23 can be mentioned. Like these compounds, the group of coumarin derivatives represented by the above general formula 1 has a high melting point and glass transition point, and as a result, the thermal stability is high.

The phosphorescent material is a phosphorescent material (phosphorescent pigment, phosphorescent dopant), and emits light from the singlet and triplet excited states at room temperature, which emits light when transitioning to the ground state by obtaining energy from the host material. It is a material that can be used. As the phosphorescent material, a material that can recombine carriers transported from the host material to be in an excited state and extract light from a singlet and a triplet when returning to a ground state can be used.
The addition amount (dope amount) of the phosphorescent material is generally 0.01% by weight or more and 30% by weight or less with respect to the host material.

The phosphorescent material is not particularly limited as long as it is a material that can utilize light emission from a singlet state and a triplet state in an excited state at normal temperature. For example, a known material selected as a phosphorescent material for a light-emitting layer, 2-phenylpyridine) iridium, bis (2-phenylpyridinato-N, C2 ′) iridium (acetylacetonate), 6-di (fluorophenyl) -pyridinate-N, C2 ′) iridium (acetylacetonate), Iridium (III) bis [4,6-di (fluorophenyl) -pyridinate-N, C2 ′] picolinate, platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ′) (2 , 4-pentaneconionate), platinum (II) (2- (4 ′, 6′-difluorophenyl) pyridinate N, C2 ′) (6-methy -2,4-heptaneconionate-O, O), bis (2- (2'-benzo [4,5-a] thienyl) pyridinate-platium (II) (2- (4 ', 6'- Difluorophenyl) pyridinate N, C3 ′) iridium (acetylacetonate), etc. In general, phosphorescent heavy metal complexes are often used.
For example, tris (2-phenylpyridine) iridium can be used as the green phosphorescent material. As the red phosphorescent material, 2,3,7,8,12,13,17,18-octaethyl-21H23H-porphine platinum (II) can be used. Moreover, you may change the center metal of these materials into another metal or a nonmetal.

The light emitting layer may be provided on the hole injecting and transporting layer by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.
The film thickness is generally about 1 nm to 100 nm, preferably about 2 to 50 nm, although it depends on the material used.

In addition, by adding a plurality of dopants in the same layer, the emission color is mixed, or two or more lights are emitted, or after energy transfer from the host material to the low energy first dopant, It is possible to efficiently transfer energy to the dopant.
When the host material adopts a mechanism that transports carriers to the dopant and causes recombination in the carriers, the efficiency of carrier movement can be improved.

  Note that the chromaticity, saturation, brightness, luminance, and the like of the light emitted from the light emitting layer can be adjusted by selecting the type of material forming the light emitting layer, adjusting the amount of addition, adjusting the film thickness, and the like.

Further, as described above, the light emitting layer may have a laminated structure, and each layer may emit light having a wavelength (peak wavelength) different from at least the other layer. When white is expressed by such a laminated structure, for example, the following layer configuration may be adopted.
・ (Anode side) / Red light emitting layer / Blue light emitting layer / Green light emitting layer / (Cathode side)
・ (Anode side) / Red light emitting layer / Green light emitting layer / Blue light emitting layer / (Cathode side)
・ (Anode side) / Green light emitting layer / Blue light emitting layer / Red light emitting layer / (Cathode side)
・ (Anode side) / Green light emitting layer / Red light emitting layer / Blue light emitting layer / (Cathode side)
・ (Anode side) / Blue light emitting layer / Red light emitting layer / Green light emitting layer / (Cathode side)
・ (Anode side) / Blue light emitting layer / Green light emitting layer / Red light emitting layer / (Cathode side)
・ (Anode side) / Red and green light emitting layer / Blue light emitting layer / (Cathode side)
・ (Anode side) / Blue light emitting layer / Red and green light emitting layer / (Cathode side)
・ (Anode side) / Red light emitting layer / Green and blue light emitting layer / (Cathode side)
・ (Anode side) / Green and blue light emitting layer / Red light emitting layer / (Cathode side)
・ (Anode side) / Red and blue light emitting layer / Green light emitting layer / (Cathode side)
・ (Anode side) / Green light emitting layer / Red and blue light emitting layer / (Cathode side)
・ (Anode side) / Red, green and blue light emitting layer (white light emitting layer) / (Cathode side)

  In the above layer structure, white is expressed by red, green, and blue, but in a complementary color relationship such as blue light emitting layer / yellow light emitting layer, light blue light emitting layer / orange light emitting layer, green light emitting layer / purple light emitting layer. A certain color may be emitted to express white. Of course, colors other than white may be expressed.

The blue light-emitting layer is preferably formed on the cathode side of the red and green light-emitting layers by mixing a dopant having a blue emission color and a host material, for example, by co-evaporation.
As the dopant whose emission color is blue, known dopants for blue light emission can be appropriately employed. For example, distyrylamine derivatives, pyrene derivatives, perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, chrysene Derivatives, phenanthrene derivatives, distyrylbenzene derivatives, tetraphenylbutadiene and the like can be mentioned.

  As the host material for the blue light-emitting layer, a known host material used in the light-emitting layer of the organic EL element having a blue emission color can be appropriately employed. For example, a distyrylarylene derivative, a stilbene derivative, a carbazole derivative, a triaryl Examples thereof include amine derivatives, anthracene derivatives, pyrene derivatives, coronene derivatives, bis (2-methyl-8-quinolinolato) (p-phenylphenolato) aluminum (BAlq), and the like.

  Examples of the dopant whose emission color is red include, for example, a europium complex, a benzopyran derivative, a rhodamine derivative, a benzothioxanthene derivative, a porphyrin derivative, Nile red, 2- (1,1-dimethylethyl) -6- (2- (2, 3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolizin-9-yl) ethenyl) -4H-pyran-4H-ylidene) propanedinitrile (DCJTB) And DCM.

  Examples of the dopant having a green emission color include a coumarin derivative and a quinacridone derivative.

  As a host material used for a red light emitting layer or a green light emitting layer, a known host material used in a light emitting layer of an organic EL element having a light emission color of red or green can be appropriately employed. For example, a distyrylarylene derivative or distyryl is used. Benzene derivatives, distyrylamine derivatives, quinolinolato metal complexes, triarylamine derivatives, oxadiazole derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, etc. Alq3, a tetramer of triphenylamine, and 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) are particularly preferably used.

  A light emitting layer that emits a plurality of colors, such as red and green light emitting layers, can be formed by, for example, mixing a dopant that emits each color and a host material by co-evaporation or the like.

  There are the following methods for adjusting the emission color of the light emitting layer. The emission color may be adjusted using one or more of these methods.

A method of adjusting by providing a color filter on the light extraction side of the light emitting layer.
The color filter adjusts the emission color by limiting the wavelength to transmit. As the color filter, for example, cobalt oxide is used as a blue filter, a mixed system of cobalt oxide and chromium oxide is used as a green filter, and a known material such as iron oxide is used as a red filter. It may be formed on the substrate 2 using the thin film deposition method.

A method of adjusting the emission color by adding a material that promotes or inhibits emission.
For example, a so-called assist dopant that receives energy from the host material and transfers this energy to the dopant can be added to facilitate energy transfer from the host material to the dopant. As an assist dopant, it selects from a well-known material suitably, for example, may be selected from the above-mentioned host material and the material which can be utilized as a dopant.

A method of adjusting the emission color by adding a wavelength converting material to a layer (including the substrate 2) on the light extraction side of the light emitting layer.
As this material, a known wavelength conversion material can be used. For example, a fluorescence conversion substance that converts light emitted from the light emitting layer into other light having a low energy wavelength can be used. The type of the fluorescence conversion substance is appropriately selected according to the wavelength of light to be emitted from the target organic EL device and the wavelength of light emitted from the light emitting layer. The amount of the fluorescent conversion substance used can be appropriately selected according to the type within a range that does not cause concentration quenching, but is 10 ⁻⁵ to 10 ⁻⁴ mol / percent of the transparent resin (uncured). A liter is appropriate. Only one type of fluorescent conversion substance may be used, or a plurality of types may be used in combination. When a plurality of types are used in combination, white light or intermediate color light can be emitted in addition to blue light, green light, and red light. Specific examples of the fluorescence conversion substance include the following substances (a) to (c).

(A) What emits blue light when excited by ultraviolet light, Stilbene dyes such as 1,4-bis (2-methylstyrin) benzene, trans-4,4'-diphenylstilbene, 7-hydroxy-4-methylcoumarin Coumarin dyes such as 4,4'-bis (2,2-diphenylvinyl) biphenyl and other aromatic dimethylidin dyes.

(B) one that emits green light when excited by blue light 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin (coumarin 153 ) And other coumarin dyes.

(C) Excited by light having a wavelength from blue to green and emitting light having a wavelength from orange to red 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyrylyl) -4H -Pyran, 4- (dicyanomethylene) -2-phenyl-6- (2- (9-eurolidyl) ethenyl) -4H-pyran, 4- (dicyanomethylene) -2,6-di (2- (9-eurolidyl) ) Ethenyl) -4H-pyran, 4- (dicyanomethylene) -2-methyl-6- (2- (9-eurolidyl) ethenyl) -4H-pyran, 4- (dicyanomethylene) -2-methyl-6- ( Cyanine dyes such as 2- (9-eurolidyl) ethenyl) -4H-thiopyran, 1-ethyl-2- (4- (p-dimethylaminophenyl) -1,3-butadienyl) -pyridium- Pyridine dyes such as percollate (pyridine 1), xanthine dyes such as rhodamine B and rhodamine 6G, and oxazine dyes.

《Electron injection transport layer》
An electron injection transport layer is a layer provided between a cathode and a light emitting layer, and is a layer which transports the electron inject | poured from the cathode to a light emitting layer, and provides the following properties to an organic EL element.
・ Drive voltage is lowered.
・ Since electron injection from the cathode to the light emitting layer is stabilized, the service life is extended.
-Since the adhesion between the cathode and the light emitting layer is increased, the uniformity of the light emitting surface can be increased.
-Covers the protrusions of the cathode and reduces device defects.

As a material for forming an electron injection / transport layer, a known material that can be used as an electron injection material of a photoconductive material, or an arbitrary material among known materials used for an electron injection / transport layer of an organic EL device In general, a material whose electron affinity is between the work function of the cathode and the electron affinity of the light emitting layer is used.
Specifically, 1,3-bis [5 ′-(p-tert-butylphenyl) -1,3,4-oxadiazol-2′-yl] benzene or 2- (4-bifinylyl) -5- Oxadiazole derivatives such as (4-t-butylphenyl) -1,3,4-oxadiazole; 3- (4′-tert-butylphenyl) -4-phenyl-5- (4 ″ -biphenyl) Triazine derivatives such as -1,2,4-triazole, etc. Triazine derivatives, perylene derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorenone derivatives, thiopyrandioxide derivatives, anthraquinodis Heterocyclic tetracarboxylic anhydrides such as methane derivatives, thiopyran dioxide derivatives, naphthalene perylene, carbodiimi It can be used fluorenylidene methane derivatives, anthraquinodimethane derivatives, anthrone derivatives, distyryl pyrazine derivatives, silole derivatives, phenanthroline derivatives, also imidazopyridine derivatives.

  Organometallic complexes such as bis (10-benzo [h] quinolinolato) beryllium, beryllium salt of 5-hydroxyflavone, and aluminum salt of 5-hydroxyflavone are also preferably selected, but 8-hydroxyquinoline or its derivatives A metal complex is also particularly suitably selected. Specific examples include metal chelate oxinoid compounds containing chelates of oxine (generally 8-quinolinol or 8-hydroxyquinoline) such as tris (8-quinolinol) aluminum and tris (5,7-dichloro-8-quinolinol). Examples thereof include aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, and tris (2-methyl-8-quinolinol) aluminum. Moreover, the metal complex etc. which the center metal of these metal complexes replaced with indium, magnesium, copper, calcium, tin, zinc, or lead are mentioned. Metal-free or metal phthalocyanine or those having a terminal substituted with an alkyl group or a sulfone group is also preferably used.

  The electron injecting and transporting layer may be formed of only one kind of material as described above, or may be formed by mixing a plurality. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

The electron injecting and transporting layer is formed by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, a spin coating method, or an electron beam vapor deposition method using the above-described materials.
The film thickness varies depending on the material used, but is usually 5 nm to 5 μm.

  In addition, when an electron injection transport layer is provided in the light extraction side rather than a light emitting layer, it needs to be transparent with respect to the light to extract. Therefore, a material that is transparent to the light when it is thinned is appropriately selected from the materials that can form the electron injecting and transporting layer as described above, and generally the transmittance for the extracted light is more than 10%. Set to be larger.

《Other layers, additives》
The organic EL element according to the present embodiment may be provided with a known layer other than the above-described layers, or a known additive (dopant) or the like may be added (doping) to the constituent layers. Good.

For example, when providing the layers shown in the above-described layer configuration examples such as an electron transport layer, a hole transport layer, a hole injection layer, etc., pay attention to the functions (carrier transport function, carrier injection function) assigned to these layers. Then, an appropriate material may be selected from the materials as described above and manufactured in the same manner as each layer described above.
Further, for example, it can be modified as follows.

<Layers provided between the above layers>
You may provide the layer for improving the adhesiveness of layers, or improving electron injection property or hole injection property.
For example, a cathode interface layer (mixed electrode) in which a material for forming a cathode and a material for forming an electron injecting and transporting layer are co-evaporated may be provided between the two. Thereby, the energy barrier of the electron injection which exists between a light emitting layer and a cathode can be eased. In addition, the adhesion between the cathode and the electron injecting and transporting layer can be improved.
The material for forming the cathode interface layer can be used without particular limitation as long as it is a material that imparts the above performance to the cathode interface layer, and known materials can also be used. For example, use of alkali metal such as lithium fluoride, lithium oxide, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, fluoride of alkaline earth metal, oxide, chloride, sulfide, etc. it can. The cathode interface layer may be formed of a single material or a plurality of materials.
The film thickness is about 0.1 nm to 10 nm, preferably 0.3 nm to 3 nm.
The cathode interface layer may be formed uniformly in the cathode interface layer, may be formed non-uniformly, may be formed in an island shape, or a known thin film forming method such as a vacuum evaporation method. Can be formed.

  A layer (block layer) that prevents the movement of holes, electrons, excitons, and the like may be provided in at least one of the layers described above. For example, a hole blocking layer may be provided adjacent to the cathode side of the light emitting layer in order to prevent holes from passing through the light emitting layer and to efficiently recombine with electrons in the light emitting layer. Examples of the material for forming the hole block layer include known materials such as triazole derivatives, oxadiazole derivatives, BAlq, and phenanthroline derivatives, but are not particularly limited thereto.

  A layer (buffer layer) that relaxes a hole or electron injection barrier may be provided in at least one of the above-described layers. For example, a buffer layer may be inserted between the anode and the hole injecting and transporting layer transporting layer, or between the organic layers stacked adjacent to the anode for the purpose of relaxing the injection barrier against hole injection. As a material for forming the buffer layer, a known material such as copper phthalocyanine is used, but is not particularly limited thereto.

<Protective layer>
For the purpose of preventing the organic EL element from coming into contact with oxygen or moisture, a protective layer (sealing layer, passivation film) may be provided on the side opposite to the substrate.
Examples of the material used for the protective layer include organic polymer materials, inorganic materials, and photocurable resins. The materials used for the protective layer may be used alone or in combination. You may use together. The protective layer may have a single layer structure or a multilayer structure.
Examples of organic polymer materials include fluorinated resins such as chlorotrifluoroethylene polymer, dichlorodifluoroethylene polymer, a copolymer of chlorotrifluoroethylene polymer and dichlorodifluoroethylene polymer, polymethyl methacrylate, poly Acrylic resins such as acrylate, epoxy resins, silicone resins, epoxy silicone resins, polystyrene resins, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyamideimide resins, polyparaxylene resins, polyethylene resins, polyphenylene oxide resins, etc. be able to.
Examples of the inorganic material include polysilazane, diamond thin film, amorphous silica, electrically insulating glass, metal oxide, metal nitride, metal carbonide, metal sulfide and the like.

In addition, you may add an above described fluorescence conversion substance to the above materials.
In addition, the organic EL element can be protected by being enclosed in an inert substance such as paraffin, liquid paraffin, silicon oil, fluorocarbon oil, or zeolite-added fluorocarbon oil.

  Naturally, it may be protected by can sealing. Specifically, the organic layer may be sealed with a sealing member such as a sealing plate or a sealing container for the purpose of blocking moisture and oxygen from the outside. Even if it installs a sealing member only in the electrode side of a back side, you may cover the whole organic EL element with a sealing member. The shape, size, thickness and the like of the sealing member are not particularly limited as long as the organic layer can be sealed and external air can be blocked. As a material used for the sealing member, glass, stainless steel, metal (aluminum, etc.), plastic (polychlorotrifluoroethylene, polyester, polycarbonate, etc.), ceramic, or the like can be used.

  When installing the sealing member on the organic EL element, a sealing agent (adhesive) may be used as appropriate. When covering the whole organic EL element with a sealing member, you may heat-seal sealing members without using a sealing agent. As the sealant, an ultraviolet curable resin, a thermosetting resin, a two-component curable resin, or the like can be used.

  Further, a water absorbent or an inert liquid may be inserted into the space between the sealing container and the organic EL element. The moisture absorbent is not particularly limited, and specific examples include barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride, cesium fluoride. , Niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide and the like. As the inert liquid, paraffins, liquid paraffins, fluorinated solvents (perfluoroalkane, perfluoroamine, perfluoroether, etc.), chlorinated solvents, silicone oils, and the like can be used.

<Doping to hole injection transport layer and electron injection transport layer>
The hole injecting and transporting layer and the electron injecting and transporting layer may be doped with an organic light emitting material (dopant) such as a fluorescent material or a phosphorescent material, and these layers may emit light.

<Doping of alkali metal or alkali metal compound to the layer adjacent to the cathode>
When a metal such as aluminum is used for the cathode, an alkali metal or an alkali metal compound may be doped into a layer adjacent to the cathode in order to reduce the energy barrier between the cathode and the organic light emitting layer 31. Since the organic layer is reduced by the added metal or metal compound to generate anions, the electron injecting property is increased and the applied voltage is decreased. Examples of the alkali metal compound include oxides, fluorides, and lithium chelates.

-Example which deform | transforms anode 12 formation material The material which forms the anode 12 is not restricted to chromium, You may form with transparent conductive materials, such as another metal and ITO. In addition, since a thing with a larger work function can inject | pour a hole easily, it can employ | adopt preferably. The work function (unit: eV) is 4.5 for chromium, 5.15 for nickel, 5.1 for gold, 5.55 for palladium, 4.8 for ITO, and 4.65 for copper.
More specifically, it can be configured as follows.

The anode is an electrode that injects holes into an organic layer such as a hole injection transport layer. Therefore, the material for forming the anode may be any material that imparts this property to the anode. Generally, a known material such as a metal, an alloy, an electrically conductive compound, or a mixture thereof is selected and the surface (hole The work function of the surface in contact with the injection transport layer 11 is 4 eV or more.
Examples of materials for forming the anode include the following.

Metal oxides and metal nitrides such as ITO (indium-tin-oxide), IZO (indium-zinc-oxide), tin oxide, zinc oxide, zinc aluminum oxide, titanium nitride;
Metals such as gold, platinum, silver, copper, aluminum, nickel, cobalt, lead, chromium, molybdenum, tungsten, tantalum, niobium;
These metal alloys and copper iodide alloys,
Conductive polymers such as polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, poly (3-methylthiophene), and polyphenylene sulfide.

When the anode is provided on the light extraction side with respect to the light emitting layer, generally, the anode is set so that the transmittance for the extracted light is larger than 10%. When extracting light in the visible light region, ITO having high transmittance in the visible light region is preferably used.
When used as a reflective electrode, a material having the ability to reflect the light extracted to the outside is appropriately selected from the above materials, and generally a metal, an alloy, or a metal compound is selected.

  The anode may be formed of only one kind of material as described above, or may be formed by mixing a plurality of materials. Moreover, the multilayer structure which consists of several layers of the same composition or a different composition may be sufficient.

  When the resistance of the anode is high, an auxiliary electrode may be provided to lower the resistance. The auxiliary electrode is an electrode in which a metal such as copper, chromium, aluminum, titanium, an aluminum alloy, a silver alloy, or a laminate thereof is partially attached to the anode.

The anode is formed by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum vapor deposition method, a spin coating method, or an electron beam vapor deposition method using the above-described materials.
Further, in order to clean the anode surface, UV ozone cleaning or plasma cleaning may be performed. Moreover, the work function of the anode surface can be changed by performing plasma cleaning. In order to suppress the occurrence of short circuits and defects in the organic EL element, the surface roughness may be controlled to 20 nm or less as a mean square value by a method of reducing the particle size or a method of polishing after film formation.

Although the film thickness of the anode depends on the material used, it is generally in the range of about 5 nm to 1 μm, preferably about 10 nm to 1 μm, more preferably about 10 to 500 nm, particularly preferably about 10 nm to 300 nm, desirably 10 to 200 nm. Selected.
The sheet electrical resistance of the anode is preferably set to several hundred Ω / □ or less, more preferably about 5 to 50 Ω / □.

-Configuration example in which the anode 12 does not have light reflectivity The anode 12 may not have light reflectivity.
However, since the light having the reflectivity from the light emitting layers 17 and 22 toward the anode 12 is reflected by the anode 12 and emitted from the cathode 14 side, the reflected light of the anode 12 is not used. The amount of light emitted from the cathode 14 can be increased. Therefore, even if the light emission amount of the light emitting layers 17 and 22 is reduced, a necessary light amount can be obtained and the power consumption can be reduced.

-Configuration employing non-transparent substrate The substrate 11 may not be transparent. For example, a hard material such as metal or ceramics may be used, or a flexible substrate such as resin may be used.
Specifically, the substrate may be configured as follows.

  The substrate is a mainly plate-like member that supports the organic EL element. An organic EL element is generally manufactured as an organic EL device supported by a substrate because each layer constituting the organic EL element is very thin.

Since the substrate is a member on which the organic EL elements are laminated, it is preferable that the substrate has planar smoothness.
Further, when the substrate is on the light extraction side with respect to the light emitting layer, it is transparent to the extracted light.

  Any known substrate can be used as long as it has the above-described performance. In general, a ceramic substrate such as a glass substrate, a silicon substrate, or a quartz substrate, or a plastic substrate is selected. Also, a metal substrate or a substrate in which a metal stay is formed on a support is used. Furthermore, a substrate made of a composite sheet in which a plurality of substrates of the same type or different types are combined can also be used.

In the above embodiment, the resistance value of the cathode is defined as in (i) above. However, instead of defining in this way, the sheet resistance of the cathode is defined as follows. A top emission type organic EL device having a good transparent cathode can be provided.
-The sheet resistance of the cathode should be more than 0Ω / □ and less than 10Ω / □.

  Moreover, even if it does not prescribe | regulate the resistance value of a cathode like said (i), the top emission type organic EL element provided with the favorable transparent cathode can be provided. In other words, when configured as shown in (ii) below, a top emission type organic EL element having performance equal to or higher than that of a conventional top emission type organic EL element employing ITO as a transparent cathode can be obtained. Further, when the resistance value of the cathode is defined as in (i) above or the sheet resistance of the cathode is defined as described above, an extremely good organic EL element can be obtained.

(Ii) In a top emission type device in which an anode, an organic layer, and a cathode are sequentially laminated on a substrate and light emitted from the organic layer is extracted from the side opposite to the substrate, that is, from the cathode side, the cathode is set as follows. Organic EL element.
-It consists of an electron injection layer and a coating layer.
The electron injection layer is formed transparently using a metal, a metal alloy, or a metal compound as a material, and is provided so as to be in contact with the organic layer.
The covering layer is made of a metal or metal alloy as a transparent material, and is formed so as to cover the surface of the electron injection layer opposite to the surface facing the organic layer, and protects the electron injection layer from the outside.

  Further, as is clear from the above description, the cathode is not limited to only the top emission type element because it has the same or better effect than the conventional transparent cathode made of ITO. It can also be used for devices. In other words, when the cathode is disposed on the light extraction side with respect to the organic layer, it functions as a very good electrode as described above, and can replace the conventional transparent cathode made of ITO. More specifically, any one of the following organic EL elements (iii) to (v) can be replaced with a conventional organic EL element having a transparent cathode formed of ITO.

(Iii) An organic EL element in which an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially stacked on a substrate, and light emission of the light emitting layer is extracted from at least the cathode side with reference to the light emitting layer. There,
The cathode covers an electron injection layer formed transparently using a metal, a metal alloy or a metal compound, and a surface opposite to the surface of the electron injection layer facing the organic layer to protect the electron injection layer Made of ITO (indium tin oxide) made of a metal or a metal alloy that is transparently formed of a metal alloy and having the cathode having the same resistance value and the same shape as the cathode. The organic EL element formed so that it may become below the resistance value of a transparent electrode.

(Iv) An organic EL element in which an anode, an organic layer including at least a light-emitting layer, and a cathode are sequentially stacked on a substrate, and light emission of the light-emitting layer is extracted from at least the cathode side with reference to the light-emitting layer. There,
The cathode covers an electron injection layer formed transparently using a metal, a metal alloy or a metal compound, and a surface opposite to the surface of the electron injection layer facing the organic layer to protect the electron injection layer An organic EL device comprising: a coating layer formed transparently from a metal or metal alloy that plays a role of forming a sheet, and having a sheet resistance of more than 0Ω / □ and not more than 10Ω / □ .

(V) An organic EL element in which an anode, an organic layer including at least a light-emitting layer, and a cathode are sequentially stacked on a substrate, and light emission of the light-emitting layer is extracted from at least the cathode side based on the light-emitting layer. There,
The cathode covers an electron injection layer formed transparently using a metal, a metal alloy or a metal compound, and a surface opposite to the surface of the electron injection layer facing the organic layer to protect the electron injection layer An organic EL element comprising: a coating layer formed transparently from a metal or metal alloy that plays a role of

(Vi) An organic EL element in which an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially stacked on a substrate, and light emission of the light emitting layer is taken out from the side opposite to the substrate,
The organic layer includes a light emitting layer containing a fluorescent dopant and a light emitting layer containing a phosphorescent dopant, and the light emitting layer containing the fluorescent dopant is laminated on the cathode side of the light emitting layer containing the phosphorescent dopant. Organic EL element to be used.

  Note that not only the organic EL element of (i) but also any of elements (ii) to (vi) can be modified in the same manner as the element of (i), and the above modification examples are combined. It can also be configured.

The schematic diagram of the organic EL element of 1st Embodiment. The schematic diagram of the organic EL element of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Organic EL element, 11 ... Board | substrate, 12 ... Anode, 13, 21 ... Organic layer, 14 ... Cathode, 17, 22 ... Light emitting layer, 18 ... Electron injection layer, 19 ... Covering layer.

Claims (9)

An organic EL device in which an anode, an organic layer including at least a light emitting layer, and a cathode are sequentially stacked on a substrate,
The organic layer includes a light emitting layer containing a fluorescent dopant and a light emitting layer containing a phosphorescent dopant, and the light emitting layer containing the fluorescent dopant is laminated on the cathode side of the light emitting layer containing the phosphorescent dopant. Organic EL element to be used. An organic EL element in which an anode, an organic layer including at least a light-emitting layer, and a cathode are sequentially stacked on a substrate, and light emission of the light-emitting layer is extracted from a side opposite to the substrate,
The organic layer includes a light emitting layer containing a fluorescent dopant and a light emitting layer containing a phosphorescent dopant, and the light emitting layer containing the fluorescent dopant is laminated on the cathode side of the light emitting layer containing the phosphorescent dopant. Organic EL element to be used.   The organic EL device according to claim 1, wherein the fluorescent dopant is a blue fluorescent dopant.   The organic EL element according to claim 1, wherein the phosphorescent dopant is a red phosphorescent dopant.   The organic phosphor element according to claim 1, wherein the phosphorescent dopant is a green phosphorescent dopant.   The light emitting layer containing the said phosphorescent dopant contains a red phosphorescent dopant and a green phosphorescent dopant, The organic EL element as described in any one of Claims 1-3 characterized by the above-mentioned.   The organic EL device according to claim 1, wherein the light emitting layer containing the phosphorescent dopant comprises a light emitting layer containing a red phosphorescent dopant and a light emitting layer containing a green phosphorescent dopant.   The organic EL device according to claim 1, further comprising a hole block layer adjacent to a cathode side of the light emitting layer containing the fluorescent dopant.   The cathode covers an electron injection layer formed transparently using a metal, a metal alloy or a metal compound, and a surface opposite to the surface of the electron injection layer facing the organic layer to protect the electron injection layer Made of ITO (indium tin oxide) made of a metal or a metal alloy that is transparently formed of a metal alloy and having the cathode having the same resistance value and the same shape as the cathode. 3. The organic EL element according to claim 2, wherein the organic EL element is formed to have a resistance value equal to or lower than that of the transparent electrode.

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