JP4785386B2 - Organic electroluminescent device and organic electroluminescent display device - Google Patents

Description

  The present invention relates to an organic electroluminescent element and an organic electroluminescent display device.

  Organic electroluminescent elements (organic EL elements) are being actively developed from the viewpoint of application to displays and lighting. The driving principle of the organic EL element is as follows. That is, holes and electrons are injected from the anode and the cathode, respectively, and these are transported through the organic thin film, recombined in the light emitting layer to generate an excited state, and light emission can be obtained from this excited state. In order to increase the luminous efficiency, it is necessary to inject holes and electrons efficiently and transport the organic thin film. However, since the movement of carriers in the organic EL element is limited by the energy barrier between the electrode and the organic thin film and the low carrier mobility in the organic thin film, there is a limit to improving the light emission efficiency.

  On the other hand, as another method for improving the light emission efficiency, there is a method of laminating a plurality of light emitting layers. For example, it may be possible to obtain higher luminous efficiency than a single layer by laminating an orange light-emitting layer and a blue light-emitting layer that are in a complementary color relationship so as to be in direct contact with each other. For example, when the light emission efficiency of the blue light emitting layer is 10 cd / A and the light emission efficiency of the orange light emitting layer is 8 cd / A, when these are stacked to form a white light emitting element, the light emission efficiency of 15 cd / A Is obtained.

  However, when three or more light emitting layers are laminated so as to be in direct contact with each other, improvement in light emission efficiency cannot be obtained. This is because there is a limit to the expansion of the recombination region of electrons and holes, and the recombination region does not extend over three layers.

In Non-Patent Document 1, two light emitting units are stacked via inorganic semiconductor layers such as V ₂ O ₅ and ITO, carriers are generated inside the inorganic semiconductor layer, and the carriers are supplied to the two light emitting layers. A method has been reported. This method uses carriers contained in the inorganic semiconductor layer, and a high voltage must be applied in order to generate carriers. For this reason, a drive voltage becomes high and cannot be applied to low voltage drive of a portable device or the like.

  Patent Documents 1 to 4 also propose an organic EL element in which a plurality of light emitting units are stacked via a charge generation layer or the like, but it is necessary to drive at a high voltage, and high luminous efficiency can be obtained. It wasn't.

Non-Patent Document 2 describes a method for producing HAT-CN6 described later.
JP 2003-272860 A JP 2003-264085 A Japanese Patent Laid-Open No. 11-329748 JP 2004-39617 A 2004 Spring 51st Applied Physics Related Conference Lecture Proceedings No. 3 Page 1464 Lecture number 28p-ZQ-14 “Carrier recombination organic EL device with double insulation layer” SYNTHESIS, April, 1994, 378-380 “Improved Synthesis of 1,4,5,8,9,12-Hexaazatriphenylenehexacarboxylic Acid”

  An object of the present invention is to provide an organic EL element having high luminous efficiency and an organic EL display device using the same in an organic EL element in which a plurality of light emitting units are stacked.

  An organic EL device according to a first aspect of the present invention includes a cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units, and includes an intermediate unit. Has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer is a layer for extracting electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer | LUMO (A) | and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer | HOMO (B) | , | HOMO (B) | − | LUMO (A) | ≦ 2.0 eV, and the intermediate unit is configured to remove holes generated by the extraction of electrons from the adjacent layer by the electron extraction layer on the cathode side. An organic electroluminescent device that supplies an extracted light to a light emitting unit on the anode side through an electron transport layer and supplies the extracted electron to an optical unit, and the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (C) | is characterized in that the electron extraction layer is doped with an electron extraction promoting material having a relationship of | HOMO (B) |> | LUMO (C) |> | LUMO (A) |.

  An organic EL device according to a second aspect of the present invention includes a cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units. Has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer is a layer for extracting electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer | LUMO (A) | and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer | HOMO (B) | , | HOMO (B) | − | LUMO (A) | ≦ 2.0 eV, and the intermediate unit is configured to remove holes generated by the extraction of electrons from the adjacent layer by the electron extraction layer on the cathode side. An organic electroluminescent device that supplies an extracted light to a light emitting unit on the anode side through an electron transport layer and supplies the extracted electron to an optical unit, and the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (C) | is | HOMO (B) |> | LUMO (C) |> | LUMO (A) | It is characterized by being provided.

  An organic EL device according to a third aspect of the present invention includes a cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units. Has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer is a layer for extracting electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer | LUMO (A) | and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer | HOMO (B) | , | HOMO (B) | − | LUMO (A) | ≦ 2.0 eV, and the intermediate unit is configured to remove holes generated by the extraction of electrons from the adjacent layer by the electron extraction layer on the cathode side. An organic electroluminescent device that supplies an extracted light to a light emitting unit on the anode side through an electron transport layer and supplies the extracted electron to an optical unit, and the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (D) | is the absolute value | LUMO (E) | and | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron transport layer, whereas | LUMO (A) |> | LUMO (D ) |> | LUMO (E) | is characterized in that the electron-injecting organic material is doped in the electron-transporting layer and / or the electron-withdrawing layer.

  An organic EL device according to a fourth aspect of the present invention includes a cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units. Has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer is a layer for extracting electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer | LUMO (A) | and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer | HOMO (B) | , | HOMO (B) | − | LUMO (A) | ≦ 2.0 eV, and the intermediate unit is configured to remove holes generated by the extraction of electrons from the adjacent layer by the electron extraction layer on the cathode side. An organic electroluminescent device that supplies an extracted light to a light emitting unit on the anode side through an electron transport layer and supplies the extracted electron to an optical unit, and the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (D) | is the absolute value | LUMO (E) | and | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron transport layer, whereas | LUMO (A) |> | LUMO (D ) |> | LUMO (E) |, an electron injecting organic material layer made of an electron injecting organic material is provided between the electron extracting layer and the electron transporting layer.

  An organic EL device according to a fifth aspect of the present invention includes a cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units. Has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer is a layer for extracting electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer | LUMO (A) | and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer | HOMO (B) | , | HOMO (B) | − | LUMO (A) | ≦ 2.0 eV, and the intermediate unit is configured to remove holes generated by the extraction of electrons from the adjacent layer by the electron extraction layer on the cathode side. An organic electroluminescent element that supplies an extracted unit with an extracted electron to an anode side light emitting unit through an electron transport layer, and is selected from alkali metals, alkaline earth metals, and oxides thereof. At least one kind of electron injection layer is provided between the electron extraction layer and the electron transport layer, and the absolute value | LUMO (D) | of the lowest unoccupied molecular orbital (LUMO) energy level is In contrast to the absolute values | LUMO (E) | and | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the transport layer, | LUMO (A) |> | LUMO (D) |> | LUMO (E The electron injection organic material or the electron extraction layer material in the relationship |) is doped in the electron injection layer.

  Hereinafter, the function of the intermediate unit common to the first to fifth aspects of the present invention will be described.

  In the present invention, an intermediate unit is disposed between a plurality of light emitting units, and the light emitting unit is caused to emit light by supplying a carrier from the intermediate unit. Hereinafter, the function of the intermediate unit of the present invention will be described. In the following description, it is assumed that there are two light emitting units, the light emitting unit on the cathode side is the first light emitting unit, and the light emitting unit on the anode side is the second light emitting unit.

  According to the present invention, the intermediate unit is provided between the first light emitting unit and the second light emitting unit, and the electronic extraction layer is provided in the intermediate unit. An adjacent layer is provided on the cathode side of the electron extraction layer. The absolute value of the HOMO energy level of the adjacent layer | HOMO (B) | and the absolute value of the LUMO energy level of the electron extraction layer | LUMO (A) | are | HOMO (B) | --LUMO (A) │ ≦ 2.0 eV. That is, the LUMO energy level of the electron extraction layer is close to the HOMO energy level of the adjacent layer. For this reason, the electron extraction layer can extract electrons from the adjacent layer. Due to the extraction of electrons from the adjacent layer, holes are generated in the adjacent layer. When the adjacent layer is provided in the first light emitting unit, holes are generated in the first light emitting unit. Further, when the adjacent layer is provided between the electron extraction layer and the first light emitting unit, that is, provided in the intermediate unit, holes generated in the adjacent layer are formed in the first light emitting unit. Supplied. The holes supplied to the first light emitting unit recombine with the electrons from the cathode or the adjacent intermediate unit, whereby the first light emitting unit emits light.

  On the other hand, the electrons extracted by the electron extraction layer are supplied to the second light emitting unit and recombined with the holes supplied from the anode or the adjacent intermediate unit, whereby the second light emitting unit emits light.

  Therefore, according to the present invention, a recombination region can be formed in each of the first light-emitting unit and the second light-emitting unit, whereby each of the first light-emitting unit and the second light-emitting unit emits light separately. Can be made.

In the present invention, in order for the electron extraction layer to extract electrons from the adjacent layer, the LUMO energy level of the electron extraction layer is preferably closer to the HOMO energy level of the adjacent layer than the LUMO energy level of the adjacent layer. . That is, it is preferable that the absolute value | LUMO (B) | of the LUMO energy level of the adjacent layer satisfies the following relationship.
│HOMO (B) │-│LUMO (A) │ <│LUMO (A) │-│LUMO (B) │

In addition, since the absolute value of the LUMO energy level of the material used as the electron extraction layer is generally smaller than the absolute value of the energy level of the adjacent layer, the absolute value of each energy level is as follows: It is shown by the relational expression.
0eV <│HOMO (B) │-│LUMO (A) │ ≦ 2.0eV

  Each of the first light emitting unit and the second light emitting unit in the present invention may be formed of a single light emitting layer, or may be configured by laminating a plurality of light emitting layers so as to be in direct contact with each other. However, the present invention is particularly useful when at least one of the first light-emitting unit and the second light-emitting unit has a structure in which two light-emitting layers are stacked in direct contact. That is, in such a case, when the first light emitting unit and the second light emitting unit are directly stacked, a structure in which three or four light emitting layers are directly stacked is formed, and as described above, recombination of electrons and holes is performed. Due to the limited extent of the region, the recombination region does not span three or four light emitting layers. For this reason, recombination occurs at one location in the thickness direction of the three or four light emitting layers, and high luminous efficiency cannot be obtained. In addition, since the first light emitting unit and the second light emitting unit are recombined in a region different from the recombination region when each of the first light emitting unit and the second light emitting unit emits light separately, the light emission color of the combination of the first light emitting unit and the second light emitting unit Different colors may emit light.

  According to the present invention, by providing an intermediate unit between the first light emitting unit and the second light emitting unit, recombination can be performed in each of the first light emitting unit and the second light emitting unit. That is, a recombination region can be formed in each of the first light emitting unit and the second light emitting unit, and each of the first light emitting unit and the second light emitting unit can independently emit light. For this reason, while being able to obtain high luminous efficiency, it is possible to emit the same color as the emission color of the combination of the first light emitting unit and the second light emitting unit.

  In the present invention, the adjacent layer is preferably formed of a hole transporting material, and particularly preferably formed of an arylamine-based hole transporting material.

  In the present invention, the adjacent layer may be provided in the first light emitting unit. In particular, when the host material of the light emitting layer located on the intermediate unit side in the first light emitting unit is a hole transporting material suitable as the adjacent layer, the light emitting layer on the intermediate unit side in the first light emitting unit is adjacent. It can be a layer.

  In the present invention, the adjacent layer may be provided in the intermediate unit. In the case where the host material of the light emitting layer on the intermediate unit side in the first light emitting unit is not a hole transporting material suitable as the adjacent layer, it may not function as the adjacent layer. Adjacent layers can be provided in the intermediate unit. In such a case, the adjacent layer is disposed between the electron extraction layer and the first light emitting unit.

  In the present invention, the electron extraction layer can be used without particular limitation as long as the absolute value of the LUMO energy level is 2.0 eV smaller than the absolute value of the HOMO energy level of the adjacent layer. As a specific example, for example, it can be formed from a pyrazine derivative represented by the structural formula shown below.

(Here, Ar represents an aryl group, and R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, a dialkylamine group, or F, Cl, Br, I, or CN.)
In the present invention, more preferably, an electron extraction layer can be formed from a hexaazatriphenylene derivative represented by the structural formula shown below.

(Here, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, a dialkylamine group, or F, Cl, Br, I, or CN.)
The light emitting layer constituting the light emitting unit in the present invention is preferably formed from a host material and a dopant material. If necessary, a carrier-transporting second dopant material may be contained. The dopant material may be a singlet light-emitting material or a triplet light-emitting material (phosphorescent material).

  The organic EL device according to the first aspect of the present invention is the organic EL device of the present invention, wherein the absolute value | LUMO (C) | of the lowest unoccupied molecular orbital (LUMO) energy level is | HOMO (B) |> An electron extraction promoting material having a relationship of | LUMO (C) |> | LUMO (A) | is doped in the electron extraction layer. The LUMO energy level of the electron extraction promoting material has a value between the HOMO energy level of the adjacent layer and the LUMO energy level of the electron extraction layer. For this reason, in the electron extraction layer doped with such an electron extraction promoting material, electrons can be easily extracted from the adjacent layer. Therefore, according to the first aspect of the present invention, the electron extraction layer can efficiently extract electrons from the adjacent layer, so that the light emission efficiency can be further increased.

  In the organic EL device according to the second aspect of the present invention and the organic EL device of the present invention, the absolute value | LUMO (C) | of the lowest unoccupied molecular orbital (LUMO) energy level is | HOMO (B) |> | An electron extraction promoting layer made of an electron extraction promoting material having a relationship of LUMO (C) |> | LUMO (A) | is provided between the electron extraction layer and the adjacent layer. In the second aspect of the present invention, an electron extraction promoting layer made of an electron extraction promoting material is provided between the electron extraction layer and the adjacent layer. As described above, the LUMO energy level of the electron extraction promoting material has a value between the HOMO energy level of the adjacent layer and the LUMO energy level of the electron extraction layer. For this reason, compared with the case where the electron extraction layer is in direct contact with the adjacent layer, electrons can be extracted from the adjacent layer more easily. Therefore, according to the second aspect of the present invention, the electrons from the adjacent layer can be efficiently extracted, so that the light emission efficiency can be further increased.

  The organic EL device according to the third aspect of the present invention is the organic EL device of the present invention, wherein the absolute value | LUMO (D) | of the energy level of the lowest unoccupied molecular orbital (LUMO) is the lowest unoccupied molecule of the electron transport layer. There is a relationship of | LUMO (A) |> | LUMO (D) |> | LUMO (E) | with respect to absolute values | LUMO (E) | and | LUMO (A) | of orbital (LUMO) energy levels. The electron injection organic material is doped in the electron transport layer and / or the electron extraction layer. The LUMO energy level of the electron injecting organic material is a value between the LUMO energy level of the electron extraction layer and the LUMO energy level of the electron transport layer. Since such an electron injecting organic material is doped in the electron transport layer and / or the electron abstraction layer, an intermediate energy level can be provided between the electron abstraction layer and the electron transport layer. The injection of electrons from the layer into the electron transport layer can be facilitated. Therefore, according to the third aspect of the present invention, electrons can be efficiently injected from the electron extraction layer into the electron transport layer, so that the light emission efficiency can be further increased.

  The organic EL device according to the fourth aspect of the present invention is the organic EL device of the present invention, wherein the absolute value | LUMO (D) | of the energy level of the lowest unoccupied molecular orbital (LUMO) is the lowest unoccupied molecule of the electron transport layer. There is a relationship of | LUMO (A) |> | LUMO (D) |> | LUMO (E) | with respect to absolute values | LUMO (E) | and | LUMO (A) | of orbital (LUMO) energy levels. An electron injection organic material layer made of an electron injection organic material is provided between the electron extraction layer and the electron transport layer. In the fourth aspect, an electron injection organic material layer made of an electron injection organic material is provided between the electron extraction layer and the electron transport layer. Therefore, the LUMO energy level of the electron injecting organic material layer having an intermediate value between the LUMO energy level of the electron extraction layer and the LUMO energy level of the electron transport layer is provided. The injection of electrons from the electron extraction layer into the electron transport layer is promoted. Therefore, according to the fourth aspect of the present invention, electrons can be efficiently injected from the electron extraction layer into the electron transport layer, and the light emission efficiency can be further improved.

  In 1st aspect-3rd aspect of this invention, the electron injection layer which consists of at least 1 sort (s) chosen from an alkali metal, alkaline-earth metal, and those oxides is between an electron extraction layer and an electron carrying layer. Is preferably provided. The absolute value of the LUMO energy level of the electron injection layer | LUMO (F) | or the absolute value of the work function | WF (F) | is smaller than the absolute value of the LUMO energy level of the electron extraction layer | LUMO (A) | It is preferable. The electrons extracted from the electron extraction layer move to the electron injection layer and are supplied from the electron injection layer to the light emitting unit through the electron transport layer.

  The absolute value of the LUMO energy level of the electron transport layer | LUMO (E) | is the absolute value of the LUMO energy level of the electron injection layer | LUMO (F) | or the absolute value of the work function | WF (F) | Preferably it is smaller. The electrons that have moved to the electron injection layer are supplied to the light emitting unit through the electron transport layer.

  In the fourth aspect of the present invention, the electron injection layer is preferably provided between the electron extraction layer and the electron injection organic material layer. By providing the electron injection layer between the electron extraction layer and the electron injection organic material layer, electrons from the electron extraction layer can be supplied to the electron transport layer more efficiently.

  In a fifth aspect of the present invention, the electron injection layer is provided between an electron extraction layer and an electron transport layer, and the electron injection organic material or the material of the electron extraction layer is doped into the electron injection layer. It is characterized by having. By doping the electron injection organic material or the material of the electron extraction layer into the electron injection layer, electrons from the electron extraction layer can be supplied to the electron transport layer more efficiently. The electron injection layer doped with the electron injection organic material and the material of the electron extraction layer may be composed of a plurality of layers. For example, the electron injection layer is composed of a stacked structure in which a first electron injection layer doped with a material for an electron extraction layer is disposed on the cathode side, and a second electron injection layer doped with an electron injection organic material is disposed on the anode side. May be.

Examples of the alkali metal that forms the electron injection layer include Li and Cs. Examples of the alkali metal oxide include Li ₂ O. Examples of the alkaline earth metal include Mg. Further, the electron injection layer can also be formed by an alkali metal or alkaline earth metal carbonate (for example, Cs ₂ CO ₃ ).

  The electron transport layer in the intermediate unit in the present invention can be formed from a material generally used as an electron transport material in an organic EL element. Examples include phenanthroline derivatives, silole derivatives, triazole derivatives, quinolinol metal complex derivatives, oxadiazole derivatives, and the like.

  The organic electroluminescent display device of the present invention supplies an organic electroluminescent element having an element structure sandwiched between an anode and a cathode and a display signal corresponding to each display pixel to the organic electroluminescent element. An active matrix driving substrate provided with the active element and a transparent sealing substrate provided opposite to the active matrix driving substrate, and the organic electroluminescent element is disposed between the active matrix driving substrate and the sealing substrate. A top emission type organic electroluminescent display device in which an electrode provided on the sealing substrate side of the cathode and the anode is a transparent electrode, wherein the organic electroluminescent element is the first aspect of the present invention. An organic electroluminescent device according to any one of aspects 1 to 5 It is characterized in that.

  When the organic electroluminescent element is a white light emitting element, it is preferable to dispose a color filter between the sealing substrate and the organic electroluminescent element.

  Since the organic electroluminescent display device of the present invention is a top emission type display device, the light emitted by the organic electroluminescent element is emitted from the sealing substrate on the side opposite to the side where the active matrix is provided. Emitted. In general, an active matrix circuit is formed by laminating a large number of layers. In the case of a bottom emission type, emitted light is attenuated by the presence of such an active matrix circuit, but the organic electroluminescent display device of the present invention. Can emit light without being affected by such an active matrix circuit. In particular, since the organic electroluminescent device of the present invention has a plurality of light emitting units, the number of films through which emitted light passes is smaller in the case of the top emission type than in the case of the bottom emission type, so that the light interference. The degree of freedom of design for controlling the attenuation of the emitted light or the attenuation of the viewing angle of the emitted light can be increased.

  The organic EL element and the organic EL display device of the present invention are provided with a plurality of light emitting units stacked, and exhibit high luminous efficiency.

  According to the first aspect and the second aspect of the present invention, the electron extraction promoting material is doped in the electron extraction layer, or the electron extraction promotion layer made of the electron extraction promotion material has the electron extraction layer and the adjacent layer. It is provided between. For this reason, electrons can be more efficiently extracted from the adjacent layers by the electron extraction layer, and the light emission efficiency can be further increased. According to the third to fifth aspects of the present invention, the electron injection organic material is doped in the electron transport layer and / or the electron extraction layer, or the electron injection organic material or the electron extraction layer is an electron. An electron injection organic material layer doped with an injection layer or made of an electron injection organic material is provided between the electron extraction layer and the electron transport layer. Thereby, the injection | pouring of an electron from an electron extraction layer to an electron carrying layer can be performed more efficiently. For this reason, luminous efficiency can be further increased.

  FIG. 1 is a schematic cross-sectional view showing an organic EL element according to the present invention. As shown in FIG. 1, a first light emitting unit 41 and a second light emitting unit 42 are provided between the cathode 51 and the anode 52. An intermediate unit 30 is provided between the first light emitting unit 41 and the second light emitting unit 42. The first light emitting unit 41 is provided on the cathode 51 side with respect to the intermediate unit 30, and the second light emitting unit 42 is provided on the anode 52 side with respect to the intermediate unit 30.

  In the intermediate unit 30, an electron extraction layer 31 and an electron transport layer 33 are provided.

  According to the first aspect of the present invention, the electron extraction layer 31 is doped with an electron extraction promoting material. The content of the electron extraction promoting material in the electron extraction layer 31 is preferably in the range of 0.1 to 50% by weight, more preferably 1 to 45% by weight.

  According to the second aspect of the present invention, the electron extraction promoting layer 34 is provided between the electron extraction layer 31 and the first light emitting unit 41. The thickness of the electron extraction promoting layer 34 is preferably in the range of 0.1 to 100 nm, more preferably in the range of 0.5 to 50 nm.

  According to the third aspect of the present invention, the electron transport layer 33 and / or the electron extraction layer 31 is doped with an electron injection organic material. The content of the electron injection organic material is preferably in the range of 0.1 to 50% by weight, more preferably in the range of 1 to 45% by weight.

  According to the fourth aspect of the present invention, an electron injection organic material layer 35 made of an electron injection organic material is provided between the electron extraction layer 31 and the electron transport layer 33. The thickness of the electron injection organic material layer 35 is preferably in the range of 0.1 to 100 nm, and more preferably in the range of 0.5 to 50 nm.

  In the present invention, when the electron injection layer 32 is provided, it is provided between the electron extraction layer 31 and the electron transport layer 33. When the electron injection organic material layer 35 is present, the electron extraction layer 31 and the electron injection are provided. Provided between the organic material layers 35. The thickness of the electron injection layer 32 is preferably in the range of 0.1 to 100 nm, and more preferably in the range of 0.2 to 50 nm. Since the thickness of the electron injection layer 32 is very thin, the electron injection layer 32 may be diffused and doped on the surface of the adjacent electron injection organic material layer 35 or the electron transport layer 33.

  FIG. 2 is a diagram showing an energy diagram around an intermediate unit of one embodiment according to the first aspect of the present invention. The intermediate unit 30 includes an electron extraction layer 31, an electron injection layer 32, and an electron transport layer 33. On the cathode side of the electron extraction layer 31, an adjacent layer 40 that is a light emitting layer on the intermediate unit 30 side of the first light emitting unit 41 is provided. A second light emitting unit 42 is provided on the anode side of the intermediate unit 30. In FIG. 2, only the light emitting layer on the intermediate unit 30 side of the second light emitting unit 42 is shown.

  In the embodiment shown in FIG. 2, the electron extraction layer 31 is made of hexaazatriphenylene hexacarbonitrile (hereinafter referred to as “HAT-CN6”). HAT-CN6 can be manufactured by the method described in the nonpatent literature 2, for example.

  The electron injection layer 32 is made of Li (metallic lithium).

  The electron transport layer 33 is made of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline).

  The adjacent layer (light emitting layer) 40 contains NBP (N, N′-di (naphthacene-1-yl) -N, N′-diphenylbenzidine) as a host material.

  The light emitting layer shown as the second light emitting unit 42 contains TBADN (2-tertiary-butyl-9,10-di (2-naphthyl) anthracene) as a host material.

  In the embodiment shown in FIG. 2, the electron extraction layer 31 is doped with 4F-TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane). That is, 4F-TCNQ is doped as an electron extraction promoting material. 4F-TCNQ has the following structure.

  In Examples described later, OHBBDT (4, 5, 6, 7, 4 ', 5', 6 ', 7'-octahydro- [2,2'] bi [benzo [1,3]) used as an electron extraction promoting material Dithiolylidene]) has the following structure:

  In Examples described later, TPBT (2,2,2 ′, 2′-tetraphenyl-bithiapyran-4,4′-diylidene) used as an electron extraction promoting material has the following structure. .

  In addition, DTN (2,3-diphenyl-1,4,6,11-tetraaza-naphthacene) used as an electron injecting organic material in Examples described later has the following structure.

  HAT-CN6 forming the electron extraction layer 31 has the following structure.

  BCP has the following structure.

  NPB has the following structure.

  TBADN has the following structure.

  As shown in FIG. 2, the difference between the absolute value (4.4 eV) of the LUMO energy level of the electron extraction layer 31 and the absolute value (5.4 eV) of the HOMO energy level of the adjacent layer 40 is within 2.0 eV. Yes, in the case of FIG. 2, it is 1.0 eV. When this value is 2.0 eV, the electron extraction layer 31 can extract electrons from the adjacent layer 40 when a voltage is applied to the anode and the cathode. Furthermore, the smaller this value, the greater the electron extraction effect. For example, when this value is 1.5 eV, the effect of extracting electrons is greater than when this value is 2.0 eV, and it is most preferable that the value is 1.0 eV or less as shown in FIG. The electron extraction layer 31 is doped with 4F-TCNQ, and the absolute value of the LUMO energy level of this 4F-TCNQ is 4.6 eV. Therefore, by doping the electron extraction promoting material, it becomes easy to extract electrons from the adjacent layer 40, and electrons can be extracted efficiently. The extracted electrons pass through the electron injection layer 32 and the electron transport layer 33 and are supplied to the second light emitting unit 42.

  In the adjacent layer 40, holes are generated because electrons are extracted. The holes recombine with electrons supplied from the cathode in the first light emitting unit. As a result, light is emitted in the first light emitting unit.

  The electrons supplied to the second light emitting unit recombine with the holes supplied from the anode in the second light emitting unit 42. As a result, the second light emitting unit 42 emits light.

  As described above, recombination regions can be formed in the first light-emitting unit and the second light-emitting unit, respectively, and light can be emitted. Therefore, it is possible to increase the light emission efficiency and to emit the light emission colors of the first light emission unit and the second light emission unit.

  FIG. 3 is a diagram showing an energy diagram around the intermediate unit according to the first and fourth aspects of the present invention. In the embodiment shown in FIG. 3, an electron injection organic material layer 35 made of DTN is provided between the electron extraction layer 31 and the electron transport layer 33.

  As in the embodiment shown in FIG. 2, the electron extraction layer 31 is doped with 4F-TCNQ as an electron extraction promoting material. Therefore, electrons can be easily extracted from the adjacent layer 40. The electrons extracted by the electron extraction layer 31 are supplied to the electron transport layer 33. An electron injection organic material layer 35 is provided between the electron extraction layer 31 and the electron transport layer 33, and the energy of the LUMO is provided. Since the level is a value between the electron extraction layer 31 and the electron transport layer 33, electrons can be efficiently injected into the electron transport layer 33.

  In the embodiment shown in FIG. 3, an electron organic material layer 35 made of an electron injecting organic material is provided between the electron extraction layer 31 and the electron transport layer 33. According to the third aspect of the present invention, the electron organic material layer 35 is made of DTN. Similar effects can be obtained by doping the electron extraction layer 31 and / or the electron transport layer 33 with an electron injection organic material.

  In each of the embodiments shown in FIGS. 2 and 3, the electron extraction layer 31 is doped with 4F-TCNQ, which is an electron extraction promoting material, but the electron extraction promoting layer 34 made of 4F-TCNQ is added to the adjacent layer. Even if it is provided between 40 and the electron extraction layer 31, the same effect can be obtained.

<Experiment 1>
(Examples 1-12 and Comparative Examples 1-3)
The organic EL elements of Examples 1 to 12 and Comparative Examples 1 to 3 having the anode, hole injection layer, second light emitting unit, intermediate unit, first light emitting unit, electron transport layer, and cathode shown in Table 1 were prepared. did.

The anode was prepared by forming a fluorocarbon (CF _x ) layer on a glass substrate on which an ITO (indium tin oxide) film was formed. The fluorocarbon layer was formed by plasma polymerization of CHF ₃ gas. The thickness of the fluorocarbon layer was 1 nm.

  A hole injection layer, a second light emitting unit, an intermediate unit, a first light emitting unit, an electron transport layer, and a cathode were sequentially deposited on the anode manufactured as described above by an evaporation method.

  The first light emitting unit and the second light emitting unit are formed by laminating an orange light emitting layer (NPB + 10% tBuDPN + 3.0% DBzR) and a blue light emitting layer (TBADN + 20% NPB + 2.5% TBP). In any light emitting unit, the orange light emitting layer is located on the anode side, and the blue light emitting layer is located on the cathode side. % Is% by weight unless otherwise specified.

  In the orange light emitting layer, NPB and tBuDPN are used as host materials, and DBzR is used as a dopant material. DBzR is 5,12-bis {4- (6-methylbenzothiazol-2-yl) phenyl} -6,11-diphenylnaphthacene and has the following structure.

  tBuDPN is 5,12-bis (4-tertiary-butylphenyl) naphthacene and has the following structure.

  The blue light emitting layer uses TBADN and NPB as host materials, and uses TBP as a dopant material.

  TBP is 2,5,8,11-tetra-tertiary-butylperylene and has the following structure.

About each produced organic EL element, luminous efficiency was measured and the measurement result was shown in Table 1 with the drive voltage. The luminous efficiency is a value at 10 mA / cm ² .

  As shown in Table 1, in Example 1, 4F-TCNQ is doped into the electron transport layer as an electron extraction promoting material. In Example 2, OHBBDT is doped into the electron extraction layer as an electron extraction promoting material. In Example 3, the electron extraction layer is doped with TPBT as an electron extraction promoting material.

  In Example 4, the electron extraction promoting layer made of TPBT is provided between the electron transport layer and the orange light emitting layer of the first light emitting unit which is an adjacent layer.

In Example 5, an electron injection organic material layer made of DTN, which is an electron injection organic material, is provided between an electron transport layer made of BCP and an electron injection layer made of Li ₂ O.

In Example 6, a BCP layer doped with 50% DTN is provided between an electron transport layer made of BCP and an electron injection layer made of Li ₂ O. Therefore, an electron injection organic material made of DTN is doped on the surface of the electron transport layer.

In Example 7, an electron injection organic material layer made of DTN is provided between an electron transport layer made of BCP and an electron injection layer made of Li ₂ O. The electron extraction layer is doped with an electron extraction promoting material made of 4F-TCNQ.

In Example 8, an electron injection organic material layer made of DTN is provided between an electron transport layer made of BCP and an electron injection layer made of Li ₂ O. The electron extraction layer is doped with 4F-TCNQ, and as an adjacent layer, a layer made of NPB is provided in the intermediate unit.

  In Example 9, a layer made of HAT-CN6 doped with 50% DTN is provided between the electron extraction layer and the electron transport layer made of BCP. Accordingly, the surface of the electron extraction layer is doped with an electron injection organic material made of DTN.

  In Example 10, an electron injection organic material layer made of DTN is provided between an electron transport layer made of BCP and an electron injection layer made of Li. The electron extraction layer is doped with 4F-TCNQ, and an adjacent layer made of NPB is provided in the intermediate unit.

  In Example 11, an electron injection organic material layer made of DTN is provided between an electron transport layer made of BCP and an electron injection layer made of Cs. The electron extraction layer is doped with an electron extraction promoting material made of 4F-TCNQ. The intermediate unit is provided with an adjacent layer made of NPB.

  In Example 12, the electron extraction layer is doped with an electron extraction promoting material made of 4F-TCNQ.

  In Example 13, the electron injection layer made of Mg is doped with 50% of HAT-CN6 as a material for the electron extraction layer. Note that the work function of Mg is −3.7 eV.

  In Example 14, the electron injection layer made of Mg is doped with 50% of DTN as an electron injection organic material.

  In Example 15, a first electron injection layer in which Mg is doped with 50% HAT-CN6 and a second electron injection layer in which Mg is doped with 50% DTN are provided. The first electron injection layer is disposed on the cathode side, and the second electron injection layer is disposed on the anode side.

  In Comparative Example 1, only the electron extraction layer and the electron transport layer are provided in the intermediate unit.

  In Comparative Example 2, only the electron extraction layer, the electron injection layer, and the electron transport layer are provided.

  In Comparative Example 3, no intermediate unit is provided.

  As is apparent from the results shown in Table 1, Examples 1 to 3 according to the first aspect of the present invention show better luminous efficiency than Comparative Examples 1 to 3.

  Example 4 according to the second aspect of the present invention shows better luminous efficiency than Comparative Examples 1 to 3.

  Example 5 according to the fourth aspect of the present invention shows better luminous efficiency than Comparative Examples 1 to 3.

  Example 6 according to the third aspect of the present invention shows better luminous efficiency than Comparative Examples 1 to 3.

  Examples 7 and 8 according to the first and fourth aspects of the present invention show better luminous efficiency than Comparative Examples 1 to 3.

  Example 9 according to the third aspect of the present invention shows better luminous efficiency than Comparative Examples 1 to 3.

  Examples 10 and 11 according to the first aspect and the fourth aspect of the present invention show better luminous efficiency than Comparative Examples 1 to 3.

  Example 12 according to the first aspect of the present invention shows better luminous efficiency than Comparative Examples 1 to 3.

  Examples 13 to 15 according to the fifth aspect of the present invention show better luminous efficiency than Comparative Examples 1 to 3.

  Table 2 shows the absolute value of the HOMO energy level of 4F-TCNQ, OHBBDT, TPBT, DTN, HAT-CN6, NPB, and BCP, and the absolute value of the LUMO energy level.

  As shown in Table 2, in the present invention, the absolute value of the LUMO energy level of 4F-TCNQ, OHBBDT, and TPBT used as the electron extraction promoting material is the energy level of the LUMO energy level of HAT-CN6 of the electron extraction layer. It is higher than the absolute value and lower than the absolute value of the HOMO energy level of NPB which is the host material of the adjacent layer.

  In the present invention, the LUMO energy level of DTN used as the electron injecting organic material is smaller than the absolute value of the HAT-CN6 LUMO energy level of the electron extraction layer, and the BCP LUMO energy level of the electron transport layer. It is larger than the absolute value of.

  FIG. 4 is a cross-sectional view showing an organic EL display device including an organic EL element according to an embodiment of the present invention. In this organic EL display device, light emission in each pixel is driven using a TFT as an active element. A diode or the like can be used as the active element. In this organic EL element, a color filter is provided. This organic EL display device is a bottom emission type display device that emits and displays light below the substrate 1 as indicated by arrows.

Referring to FIG. 4, a first insulating layer 2 is provided on a substrate 1 made of a transparent substrate such as glass. The first insulating layer 2 is made of, for example, SiO ₂ and SiN _x . A channel region 20 made of a polysilicon layer is formed on the first insulating layer 2. A drain electrode 21 and a source electrode 23 are formed on the channel region 20, and a gate electrode 22 is provided between the drain electrode 21 and the source electrode 23 via the second insulating layer 3. Yes. A fourth insulating layer 4 is provided on the gate electrode 22. The second insulating layer 3 is made of, for example, SiN _x and SiO ₂ , and the third insulating layer 4 is made of SiO ₂ and SiN _x .

A fourth insulating layer 5 is formed on the third insulating layer 4. The fourth insulating layer 5 is made of, for example, SiN _x . A color filter layer 7 is provided in the pixel region on the fourth insulating layer 5. As the color filter layer 7, color filters such as R (red), G (green), and B (blue) are provided. A first planarizing film 6 is provided on the color filter layer 7. A through hole portion is formed in the first planarization film 6 above the drain electrode 21, and a hole injection electrode 8 made of ITO (indium oxide) formed on the first planarization film 6 is through. It is introduced in the hall. A hole injection layer 10 is formed on the hole injection electrode (anode) 8 in the pixel region. A second planarizing film 9 is formed in a portion other than the pixel region.

  On the hole injection layer 10, a white light emitting element layer 11 laminated according to the present invention is provided. The light emitting element layer 11 has a structure according to the present invention in which the first light emitting unit is laminated on the second light emitting unit via an intermediate unit. An electron transport layer 12 is provided on the light emitting element layer 11, and an electron injection electrode (cathode) 13 is provided on the electron transport layer 12.

  As described above, in the organic EL element of this example, the hole injection electrode (anode) 8, the hole injection layer 10, the light emitting element layer 11 having the structure according to the present invention, and the electron transport are formed on the pixel region. The layer 12 and the electron injection electrode (cathode) 13 are laminated to constitute an organic EL element.

  The light emitting element layer 11 emits white light. This white light emission is emitted to the outside through the substrate 1, but since the color filter layer 7 is provided on the light emission side, R, G, or B color is emitted according to the color of the color filter layer 7. The

  FIG. 5 is a sectional view showing an organic EL display device of an embodiment according to the present invention. The organic EL display device of this embodiment is a top emission type organic EL display device that emits light and displays it above the substrate 1 as shown by arrows.

  The portion from the substrate 1 to the anode 8 is fabricated in substantially the same manner as the embodiment shown in FIG. However, the color filter layer 7 is not provided on the fourth insulating layer 5 and is disposed above the organic EL element. Specifically, the color filter layer 7 is attached on a transparent sealing substrate 10 made of glass or the like, and an overcoat layer 15 is coated thereon, and this is applied to the anode 8 via the transparent adhesive layer 14. It is attached by sticking to. In this embodiment, the positions of the anode and the cathode are reversed from those in the embodiment shown in FIG.

  A transparent electrode is formed as the anode 8, and is formed, for example, by laminating ITO having a thickness of about 100 nm and silver having a thickness of about 20 nm. As the cathode 13, a reflective electrode is formed. For example, an aluminum, chromium, or silver thin film having a thickness of about 100 nm is formed. The overcoat layer 15 is formed with an acrylic resin or the like to a thickness of about 1 μm. The color filter layer 7 may be a pigment type or a dye type. Its thickness is about 1 μm.

  White light emitted from the light emitting element layer 11 is emitted to the outside through the sealing substrate 16, but since the color filter layer 7 is provided on the light emitting side, R, G or B color is emitted. Since the organic EL display device of this embodiment is a top emission type, the region where the thin film transistor is provided can also be used as the pixel region, and the color filter layer 7 is provided in a wider range than the embodiment shown in FIG. ing. The light emitting element layer 11 is formed of an organic EL element according to the present invention and is a light emitting element layer having high light emission efficiency. However, according to this embodiment, a wider area can be used as a pixel area, and thus the light emission efficiency of the light emitting element layer 11 is improved. The advantages of a high light emitting element layer can be fully utilized. Further, since the light emitting element layer having a plurality of light emitting units can be formed without considering the influence of the active matrix, the degree of freedom in design can be increased.

In the above embodiment, a glass plate is used as the sealing substrate. However, the sealing substrate is not limited to the glass plate in the present invention. For example, an oxide film such as SiO ₂ or a nitride film such as SiN _{x is used.} A film-like material can also be used as a sealing substrate. In this case, since a film-like sealing substrate can be directly formed on the element, there is no need to provide a transparent adhesive layer.

  In each of the above embodiments, an organic EL element in which two light emitting units (a first light emitting unit and a second light emitting unit) are arranged between an anode and a cathode is illustrated, but the number of light emitting units in the present invention is not limited. Is not limited to two, and three or more light emitting units may be provided, and an intermediate unit may be provided between the respective light emitting units.

The typical sectional view showing the organic EL element of one example according to the present invention. The figure which shows the energy diagram of an intermediate unit periphery. The figure which shows the energy diagram of an intermediate unit periphery. Sectional drawing which shows the bottom emission type organic electroluminescence display using the organic electroluminescent element of the Example according to this invention. Sectional drawing which shows the organic electroluminescence display of the Example according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st insulating layer 3 ... 2nd insulating layer 4 ... 3rd insulating layer 5 ... 4th insulating layer 6 ... 1st planarization film 7 ... Color filter layer 8 ... Hole injection electrode 9 DESCRIPTION OF SYMBOLS ... 2nd planarizing film 10 ... Hole injection layer 11 ... Light emitting element layer 12 ... Electron transport layer 13 ... Electron injection electrode 14 ... Transparent adhesive layer 15 ... Overcoat layer 16 ... Sealing substrate 20 ... Channel region 21 ... Drain Electrode 22 ... Gate electrode 23 ... Source electrode 30 ... Intermediate unit 31 ... Electronic extraction layer 32 ... Electron injection layer 33 ... Electron transport layer 34 ... Electronic extraction facilitating layer 35 ... Electron injection organic material layer 40 ... Adjacent layer 41 ... First Light emitting unit 42 ... second light emitting unit 51 ... cathode 52 ... anode

Claims (16)

A cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units,
The intermediate unit has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer extracts electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer. | HOMO (B) | is in a relationship of | HOMO (B) |-| LUMO (A) | ≦ 2.0 eV, and the intermediate unit is generated by extracting electrons from the adjacent layer by the electron extracting layer. And supplying the extracted holes to the light emitting unit on the cathode side and supplying the extracted electrons to the light emitting unit on the anode side through the electron transport layer. A door element,
An electron extraction promoting material in which the absolute value | LUMO (C) | of the energy level of the lowest unoccupied molecular orbital (LUMO) is in the relationship of | HOMO (B) |> | LUMO (C) |> | LUMO (A) | An organic electroluminescent device, wherein the electron extracting layer is doped. A cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units,
The intermediate unit has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer extracts electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer. | HOMO (B) | is in a relationship of | HOMO (B) |-| LUMO (A) | ≦ 2.0 eV, and the intermediate unit is generated by extracting electrons from the adjacent layer by the electron extracting layer. And supplying the extracted holes to the light emitting unit on the cathode side and supplying the extracted electrons to the light emitting unit on the anode side through the electron transport layer. A door element,
The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (C) | is from the electron extraction promoting material in the relationship of | HOMO (B) |> | LUMO (C) |> | LUMO (A) | An organic electroluminescent device, wherein an electron extraction promoting layer is provided between the electron extraction layer and the adjacent layer. A cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units,
The intermediate unit has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer extracts electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer. | HOMO (B) | is in a relationship of | HOMO (B) |-| LUMO (A) | ≦ 2.0 eV, and the intermediate unit is generated by extracting electrons from the adjacent layer by the electron extracting layer. And supplying the extracted holes to the light emitting unit on the cathode side and supplying the extracted electrons to the light emitting unit on the anode side through the electron transport layer. A door element,
The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (D) | is the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron transport layer | LUMO (E) | and | LUMO (A ) | With respect to | LUMO (A) |> | LUMO (D) |> | LUMO (E) | is doped in the electron transport layer and / or the electron extraction layer. An organic electroluminescent device characterized by comprising: A cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units,
The intermediate unit has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer extracts electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer. | HOMO (B) | is in a relationship of | HOMO (B) |-| LUMO (A) | ≦ 2.0 eV, and the intermediate unit is generated by extracting electrons from the adjacent layer by the electron extracting layer. And supplying the extracted holes to the light emitting unit on the cathode side and supplying the extracted electrons to the light emitting unit on the anode side through the electron transport layer. A door element,
The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (D) | is the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron transport layer | LUMO (E) | and | LUMO (A ) | In contrast to | LUMO (A) |> | LUMO (D) |> | LUMO (E) | An organic electroluminescent device characterized by being provided between layers.   2. The electron injection layer comprising at least one selected from alkali metals, alkaline earth metals, and oxides thereof is provided between the electron extraction layer and the electron transport layer. The organic electroluminescent element of any one of -3.   An electron injection layer made of at least one selected from alkali metals, alkaline earth metals, and oxides thereof is provided between the electron extraction layer and the electron injection organic material layer. Item 5. The organic electroluminescent device according to Item 4. A cathode, an anode, a plurality of light emitting units disposed between the cathode and the anode, and an intermediate unit disposed between the light emitting units,
The intermediate unit has an electron transport layer provided on the anode side and an electron extraction layer provided on the cathode side, and the electron extraction layer extracts electrons from an adjacent layer adjacent to the cathode side of the electron extraction layer. The absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the electron extraction layer and the absolute value of the energy level of the highest occupied molecular orbital (HOMO) of the adjacent layer. | HOMO (B) | is in a relationship of | HOMO (B) |-| LUMO (A) | ≦ 2.0 eV, and the intermediate unit is generated by extracting electrons from the adjacent layer by the electron extracting layer. And supplying the extracted holes to the light emitting unit on the cathode side and supplying the extracted electrons to the light emitting unit on the anode side through the electron transport layer. A door element,
An electron injection layer composed of at least one selected from alkali metals, alkaline earth metals, and oxides thereof is provided between the electron extraction layer and the electron transport layer;
The absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) | LUMO (D) | is the absolute value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron transport layer | LUMO (E) | and | LUMO (A ) | In contrast to | LUMO (A) |> | LUMO (D) |> | LUMO (E) |, the electron injection organic material or the electron extraction layer material is doped into the electron injection layer. An organic electroluminescent device characterized by comprising:   The organic electroluminescent element according to claim 1, wherein at least one of the light emitting units has a structure in which two light emitting layers are stacked so as to be in direct contact with each other.   The organic electroluminescent element according to claim 1, wherein the adjacent layer is provided in the light emitting unit.   The organic electroluminescent element according to claim 1, wherein the adjacent layer is provided in the intermediate unit.   The organic electroluminescent element according to claim 1, wherein the adjacent layer is made of a hole transporting material.   The organic electroluminescent device according to any one of claims 1 to 10, wherein the adjacent layer is formed of an arylamine-based hole transporting material. The organic electroluminescent device according to claim 1, wherein the electron extraction layer is formed of a pyrazine derivative represented by the structural formula shown below.

(Here, Ar represents an aryl group, and R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, a dialkylamine group, or F, Cl, Br, I, or CN.) The organic electroluminescent device according to any one of claims 1 to 12, wherein the electron extraction layer is formed of a hexaazatriphenylene derivative represented by the structural formula shown below.

(Here, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, a dialkylamine group, or F, Cl, Br, I, or CN.) An active matrix drive substrate provided with an organic electroluminescent element having an element structure sandwiched between an anode and a cathode, and an active element for supplying a display signal corresponding to each display pixel to the organic electroluminescent element And a transparent sealing substrate provided opposite to the active matrix driving substrate, the organic electroluminescent element is disposed between the active matrix driving substrate and the sealing substrate, the cathode and the A top emission type organic electroluminescent display device in which an electrode provided on the sealing substrate side of the anode is a transparent electrode,
The said organic electroluminescent element is an organic electroluminescent element of any one of Claims 1-14, The organic electroluminescent display apparatus characterized by the above-mentioned. The organic electroluminescent element according to claim 15, wherein the organic electroluminescent element is a white light emitting element, and a color filter is disposed between the organic electroluminescent element and the sealing substrate. Electroluminescent display device.

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