JP2019009411A - Organic electroluminescent element, organic electroluminescent device, and electronic apparatus - Google Patents

Abstract

An organic electroluminescent element, an organic electroluminescent device, and an electronic apparatus capable of suppressing a decrease in luminous efficiency are provided.
An organic electroluminescent device according to an embodiment of the present disclosure includes a first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode in this order. The organic electroluminescent device further includes a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the organic light emitting layer and the organic electron transport layer.
[Selection] Figure 1

Description

  The present disclosure relates to an organic electroluminescent element, an organic electroluminescent device, and an electronic apparatus.

  Various types of organic electroluminescent devices (organic electroluminescent displays) using organic electroluminescent elements have been proposed. In organic electroluminescent devices, excitons are generated when electrons and holes injected from the cathode and anode recombine in the light-emitting layer, and light is emitted when the excitons return to the low energy level or ground state. It is an element to do. Therefore, in an organic electroluminescent element, it is necessary to inject carriers effectively.

  Here, paying attention to electron injection among carrier injections, it is known to use an electron injection layer in which an organic material is doped with a low work function metal as an organic layer for injecting electrons into a light emitting layer (for example, See Patent Documents 1 to 8 below).

JP 2008-98475 A JP 2006-173230 A JP 2007-88015 A JP 2013-38432 A JP 2013-102006 A JP 2014-82524 A JP2015-109470A JP 2008-6459 A

  However, when such an electron injection layer is used, the doped metal may diffuse into the light emitting layer, and the light emission efficiency may be reduced. Therefore, it is desirable to provide an organic electroluminescent element, an organic electroluminescent device, and an electronic device that can suppress a decrease in luminous efficiency.

  The 1st organic electroluminescent element of one embodiment of this indication is provided with the 1st electrode, the organic light emitting layer, the organic electron carrying layer containing a dope metal, and the 2nd electrode in this order. The first organic electroluminescent device further includes a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the organic light emitting layer and the organic electron transport layer. .

  A second organic electroluminescent element according to an embodiment of the present disclosure includes a first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order. The second organic electroluminescent device further includes a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the organic light emitting layer and the organic electron injection layer. .

  A first organic electroluminescent device according to an embodiment of the present disclosure includes a light emitting panel having a plurality of organic electroluminescent elements and a drive circuit that drives each organic electroluminescent element. In the first organic electroluminescent device, at least one of the plurality of organic electroluminescent elements has the same components as the first organic electroluminescent element.

  A second organic electroluminescent device according to an embodiment of the present disclosure includes a light emitting panel having a plurality of organic electroluminescent elements and a drive circuit that drives each organic electroluminescent element. In the second organic electroluminescent device, at least one of the plurality of organic electroluminescent elements has the same component as the second organic electroluminescent element.

  A first electronic device according to an embodiment of the present disclosure includes an organic electroluminescent device. The organic electroluminescent device in the first electronic device has the same components as the first organic electroluminescent device.

  A second electronic device according to an embodiment of the present disclosure includes an organic electroluminescent device. The organic electroluminescent device in the second electronic device has the same components as the above-described second organic electroluminescent device.

  According to the first organic electroluminescent element, the first organic electroluminescent device, and the first electronic device of an embodiment of the present disclosure, the organic electron transport layer is disposed between the organic light emitting layer and the organic electron transport layer. Since the metal thin film comprised with the same metal as the dope metal contained, or the alloy of the same metal as the dope metal contained in the organic electron carrying layer was provided, the fall of luminous efficiency can be suppressed.

  According to the second organic electroluminescent element, the second organic electroluminescent device, and the second electronic device according to an embodiment of the present disclosure, the organic electron injection layer is interposed between the organic light emitting layer and the organic electron injection layer. Since a metal thin film made of the same metal as the doped metal contained or an alloy of the same metal as the doped metal contained in the organic electron injection layer is provided, it is possible to suppress a decrease in luminous efficiency.

  The above content is an example of the present disclosure. The effects of the present disclosure are not limited to those described above, and may be other different effects or may include other effects.

It is a figure showing an example of the section composition of the organic electroluminescence element concerning a 1st embodiment of this indication. It is a figure showing the modification of a cross-sectional structure of the organic electroluminescent element of FIG. It is a figure which represents notionally an example of the energy level of each layer of the organic electroluminescent element of FIG. It is a figure which represents notionally a modification of the energy level of each layer of the organic electroluminescent element of FIG. It is a figure showing an example of schematic structure of an organic electroluminescent device concerning a 2nd embodiment of this indication. FIG. 6 is a diagram illustrating an example of a circuit configuration of a pixel in FIG. 5. It is a figure showing the modification of a cross-sectional structure of the organic electroluminescent element of FIG. It is a figure showing the modification of a cross-sectional structure of the organic electroluminescent element of FIG. It is a figure which represents perspectively an example of the appearance of electronic equipment provided with the organic electroluminescent device of this indication. It is a figure which represents perspectively an example of the external appearance of the illuminating device provided with the organic electroluminescent element of this indication.

Hereinafter, modes for carrying out the present disclosure will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, component arrangement positions, connection forms, and the like shown in the following embodiments are merely examples and do not limit the present disclosure. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present disclosure are described as arbitrary constituent elements. Each figure is a schematic diagram and is not necessarily illustrated strictly. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, The overlapping description is abbreviate | omitted or simplified. The description will be given in the following order.

1. 1st Embodiment (organic electroluminescent element)
2. Modification of the first embodiment (organic electroluminescence device)
3. Second embodiment (organic electroluminescence device)
4). Application examples (electronic equipment, lighting equipment)

<1. First Embodiment>
[Constitution]
FIG. 1 illustrates an example of a cross-sectional configuration of the organic electroluminescent element 1 according to the first embodiment of the present disclosure. The organic electroluminescent element 1 is provided on the substrate 10, for example. The organic electroluminescent element 1 includes, for example, a light emitting layer 14 and an anode 11 and a cathode 18 disposed so as to sandwich the light emitting layer 14. The organic electroluminescent device 1 further includes, for example, a hole injection layer 12 and a hole transport layer 13 in this order from the anode 11 side between the anode 11 and the light emitting layer 14. One of the hole injection layer 12 and the hole transport layer 13 may be omitted. The organic electroluminescent device 1 further includes, for example, an electron transport layer 16 and an electron injection layer 17 in this order from the light emitting layer 14 side between the light emitting layer 14 and the cathode 18. One of the electron transport layer 16 and the electron injection layer 17 may be omitted. The organic electroluminescent element 1 further includes, for example, a diffusion suppression layer 15 that does not include an organic material between the light emitting layer 14 and the electron transport layer 16. The organic electroluminescent element 1 includes, for example, an anode 11, a hole injection layer 12, a hole transport layer 13, a light emitting layer 14, a diffusion suppression layer 15, an electron transport layer 16, an electron injection layer 17, and a cathode 18 from the substrate 10 side. The element structure is configured to include in this order. The organic electroluminescent element 1 may further include another functional layer.

  The substrate 10 is a light-transmitting substrate such as a transparent substrate, and is a glass substrate made of a glass material, for example. The substrate 10 is not limited to a glass substrate, but is a translucent resin substrate made of a translucent resin material such as polycarbonate resin or acrylic resin, or a TFT (thin film transistor) substrate that is a backplane of an organic EL display device. There may be.

  The anode 11 is formed on the substrate 10, for example. The anode 11 is a transparent electrode having translucency, for example. For the anode 11, for example, a transparent conductive film made of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) is used. The anode 11 is not limited to a transparent electrode, and may be, for example, aluminum (Al), silver (Ag), aluminum or a silver alloy, or a reflective electrode having reflectivity. The anode 11 may be a laminate of a reflective electrode and a transparent electrode.

  The hole injection layer 12 has a function of injecting holes injected from the anode 11 into the hole transport layer 13 and the light emitting layer 14. The hole injection layer 12 is made of, for example, a material (hole injection material) having a function of promoting injection of holes from the anode 11 to the hole transport layer 13 and the light emitting layer 14. Examples of the hole injecting material include Ag, Mo, chromium (Cr), vanadium (V), tungsten (W), nickel (Ni), iridium (Ir), and other oxides, or PEDOT (polythiophene). A conductive polymer material such as a mixture with polystyrene sulfonic acid).

  The hole transport layer 13 has a function of transporting holes injected from the anode 11 to the light emitting layer 14. The hole transport layer 13 is made of, for example, a material (hole transport material) having a function of transporting holes injected from the anode 11 to the light emitting layer 14. The above hole transport materials include, for example, arylamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styryl. An anthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a butadiene compound, a polystyrene derivative, a hydrazone derivative, a triphenylmethane derivative, a tetraphenylbenzine derivative, or a combination thereof.

  The light emitting layer 14 has a function of emitting fluorescence of a predetermined color by recombination of holes and electrons. The light emitting layer 14 is, for example, a coating film, and is formed, for example, by applying and drying a solution containing an organic light emitting material as a solute. The solution containing an organic light emitting material as a solute is configured to include, for example, an organic light emitting material and a solvent. The light emitting layer 14 may be comprised with the vapor deposition film.

  The light-emitting layer 14 is a layer that emits light by generating excitons by recombining holes injected from the anode 11 and electrons injected from the cathode 18 in the light-emitting layer 14. The light emitting layer 14 is made of, for example, an organic light emitting material. The organic light emitting material that is a raw material (material) of the light emitting layer 14 is a material in which a host material and a fluorescent dopant material are combined. That is, the light emitting layer 14 includes, for example, a host material and a fluorescent dopant material as an organic light emitting material. The host material mainly has a function of transporting electrons or holes, and the fluorescent dopant material has a function of fluorescent emission. The host material and the fluorescent dopant material are not limited to one type, and may be a combination of two or more types.

  As the host material of the light emitting layer 14, for example, an amine compound, a condensed polycyclic aromatic compound, or a heterocyclic compound is used. As the amine compound, for example, a monoamine derivative, a diamine derivative, a triamine derivative, or a tetraamine derivative is used. Examples of the condensed polycyclic aromatic compound include anthracene derivatives, naphthalene derivatives, naphthacene derivatives, phenanthrene derivatives, chrysene derivatives, fluoranthene derivatives, triphenylene derivatives, pentacene derivatives, and perylene derivatives. Examples of heterocyclic compounds include carbazole derivatives, furan derivatives, pyridine derivatives, pyrimidine derivatives, triazine derivatives, imidazole derivatives, pyrazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, pyrrole derivatives, indole derivatives, azaindole derivatives, Azacarbazole, a pyrazoline derivative, a pyrazolone derivative, a phthalocyanine derivative, or the like can be given.

  Moreover, as a fluorescent dopant material of the light emitting layer 14, a pyrene derivative, a fluoranthene derivative, an aryl acetylene derivative, a fluorene derivative, a perylene derivative, an oxadiazole derivative, an anthracene derivative, or a chrysene derivative is used, for example. Further, a metal complex may be used as the fluorescent dopant material of the light emitting layer 14. Examples of the metal complex include a metal atom and a ligand such as iridium (Ir), platinum (Pt), osmium (Os), gold (Au), rhenium (Re), or ruthenium (Ru). Is mentioned.

  The electron transport layer 16 has a function of transporting electrons injected from the cathode 18 to the light emitting layer 14. The electron transport layer 16 includes, for example, a material (electron transport material) having a function of transporting electrons injected from the cathode 18 to the light emitting layer 14. The electron transport layer 16 is made of, for example, a vapor deposition film. The electron transport layer 16 has a charge blocking function that suppresses penetration of charges (holes in the present embodiment) from the light emitting layer 14 to the cathode 18, a function that suppresses quenching of the excited state of the light emitting layer 14, and the like. It is preferable.

  The electron transporting material is, for example, an aromatic heterocyclic compound containing one or more heteroatoms in the molecule. Examples of the aromatic heterocyclic compound include compounds containing a pyridine ring, a pyrimidine ring, a triazine ring, a benzimidazole ring, a phenanthroline ring, a quinazoline ring or the like in the skeleton. The above electron transporting material may be doped with an electron transporting metal. In this case, the electron transport layer 16 is an organic electron transport layer containing a doped metal. By including the metal having the electron transporting property in the electron transporting layer 16, the electron transporting property of the electron transporting layer 16 can be improved. Examples of the doped metal contained in the electron transport layer 16 include transition metals such as Yb (ytterbium).

  The electron injection layer 17 has a function of injecting electrons injected from the cathode 18 into the electron transport layer 16 and the light emitting layer 14. The electron injection layer 17 is made of, for example, a material (electron injectable material) having a function of promoting injection of electrons from the cathode 18 to the electron transport layer 16 and the light emitting layer 14. The electron injecting material may be, for example, an organic material having an electron injecting property doped with a metal having an electron injecting property. At this time, the electron injection layer 17 is an organic electron injection layer containing a doped metal. The doped metal contained in the electron injection layer 17 is, for example, the same metal as the doped metal contained in the electron transport layer 16. Examples of the doped metal contained in the electron injection layer 17 include transition metals such as Yb (ytterbium). At this time, the metal doping amount of the electron transport layer 16 (organic electron transport layer) is smaller than the metal doping amount of the electron injection layer 17 (organic electron injection layer). This reduces the diffusion of the metal into the light emitting layer 14 and suppresses the decrease in the transmittance of the electron transport layer 16 and suppresses the decrease in the light emission efficiency compared to when the same amount of metal as that of the electron injection layer 17 is doped. Can do. The metal doping amount of the electron transport layer 16 (organic electron transport layer) is, for example, 15 wt%. From the viewpoint of suppressing transmittance reduction and reducing metal diffusion, the amount of metal dope in the electron transport layer 16 (organic electron transport layer) is preferably 5 wt%. The electron injection layer 17 may be a metal thin film made of the same metal as the doped metal contained in the electron transport layer 16.

  The electron injection layer 17 is an organic electron injection layer containing the same doped metal as the doped metal contained in the electron transporting layer 16, or a metal thin film made of the same metal as the doped metal contained in the electron transporting layer 16. Regardless of the thickness, the electron injection layer 17 is thinner than the electron transport layer 16. The thickness of the electron transport layer 16 is, for example, greater than 15 nm, and the thickness of the electron injection layer 17 is, for example, 15 nm or less. Since the electron transport layer 16 is doped with metal and has conductivity, even if the electron transport layer 16 is made thick, the influence on the driving voltage of the organic electroluminescent element 1 is small.

  The cathode 18 is, for example, a reflective electrode having light reflectivity, and is, for example, a metal electrode formed using a metal material having reflectivity. As the material of the cathode 18, for example, aluminum (Al), magnesium (Mg), silver (Ag), aluminum-lithium alloy, magnesium-silver alloy, or the like is used. The cathode 18 is not limited to the reflective electrode, and may be a transparent electrode such as an ITO film. In the present embodiment, when the substrate 10 and the anode 11 have a light-transmitting property and the cathode 18 has a reflecting property, the organic electroluminescent element 1 emits light from the substrate 10 side. It has a structure. In the present embodiment, when the substrate 10 and the anode 11 have reflectivity and the cathode 18 has translucency, the organic electroluminescent element 1 emits light from the cathode 18 side. It has a bottom emission structure.

  Next, the diffusion suppression layer 15 will be described. The diffusion suppression layer 15 is a layer for suppressing the diffusion of the doped metal contained in the electron transport layer 16 or the electron injection layer 17 into the light emitting layer 14. The diffusion suppression layer 15 is disposed between the light emitting layer 14 and the electron transport layer 16 or the electron injection layer 17. When the electron transport layer 16 is provided, the diffusion suppression layer 15 is in contact with the electron transport layer 16. When the electron transport layer 16 is omitted, the diffusion suppression layer 15 is in contact with the electron injection layer 17.

  The diffusion suppression layer 15 is the same as the doped metal contained in the electron transport layer 16 or the electron injection layer 17 (for example, a transition metal such as Yb) or the same doped metal contained in the electron transport layer 16 or the electron injection layer 17. It is a metal thin film made of a metal alloy (for example, a transition metal alloy such as YbIn). The thickness of the metal thin film is, for example, not less than 0.1 nm and not more than 2 nm. If the thickness of the metal thin film exceeds 2 nm, the transmittance of light transmitted through the diffusion suppression layer 15 may be reduced. Further, when the thickness of the metal thin film is less than 0.1 nm, the function of suppressing the diffusion of the doped metal contained in the electron transport layer 16 or the electron injection layer 17 into the light emitting layer 14 may be reduced. .

[effect]
Next, the effect of the organic electroluminescent element 1 of the present embodiment will be described.

  Various types of organic electroluminescent devices using organic electroluminescent elements have been proposed. In organic electroluminescent devices, excitons are generated when electrons and holes injected from the cathode and anode recombine in the light-emitting layer, and light is emitted when the excitons return to the low energy level or ground state. It is an element to do. Therefore, in an organic electroluminescent element, it is necessary to inject carriers effectively.

  Here, focusing on electron injection among carrier injections, it is known to use an electron injection layer in which an organic material is doped with a low work function metal as an organic layer for injecting electrons into a light emitting layer. However, when such an electron injection layer is used, the doped metal may diffuse into the light emitting layer, and the light emission efficiency may be reduced. In order to solve this problem, it is disclosed in Patent Documents 1 to 8 to provide a diffusion suppression layer that suppresses the diffusion of the doped metal.

  However, in the inventions described in Patent Documents 1 to 7, since various organic compounds (for example, crown ether derivatives) and their metal salts (for example, fluorides) are used for the diffusion suppression layer, the diffusion suppression layer It itself lacks stability. In particular, when a salt of an organic compound containing an alkali metal or alkaline earth metal is used for the diffusion suppression layer, the metal in the diffusion suppression layer is likely to diffuse into the light emitting layer. In the invention described in Patent Document 8, since a crystalline inorganic material (for example, Si) is used for the diffusion suppressing layer, the electron injection property and the electron transport property are poor.

  On the other hand, in the present embodiment, the same metal as the doped metal contained in the electron transport layer 16 or the electron injection layer 17, or the electron transport layer 16 or between the light emitting layer 14 and the electron transport layer 16 or the electron injection layer 17. A metal thin film (diffusion suppression layer 15) made of an alloy of the same metal as the doped metal contained in the electron injection layer 17 is provided. Thereby, the diffusion suppression layer 15 suppresses the diffusion of the doped metal contained in the electron transport layer 16 or the electron injection layer 17 into the light emitting layer 14. Moreover, since the metal contained in the diffusion suppression layer 15 and the metal contained in the layer in contact with the diffusion suppression layer 15 (electron transport layer 16 or electron injection layer 17) are the same, the diffusion suppression layer 15 and the diffusion suppression layer 15 are There is almost no electron barrier between the layers in contact with the layer. Further, even in the case where a large amount of diffusion metal is present in a portion close to the diffusion suppression layer 15 among the layers in contact with the diffusion suppression layer 15 (electron transport layer 16 or electron injection layer 17), the diffusion suppression layer The part close to 15 does not become a defect. In addition, there is no possibility that the metal contained in the diffusion suppression layer 15 causes an abnormal reaction to the diffusion suppression layer 15 and the layer in contact with the diffusion suppression layer 15. In addition, the thickness of the diffusion suppression layer 15 is, for example, 0.1 nm or more and 2 nm or less, and is very thin. Therefore, there is almost no possibility that the electron injection property is inhibited by the diffusion suppression layer 15, and the diffusion There is almost no possibility that the transmittance of light transmitted through the suppression layer 15 will decrease. Therefore, it is possible to suppress a decrease in luminous efficiency.

  In the present embodiment, the light emitting layer 14 and the electron injection layer 17 are formed of the same metal as the metal included in the electron injection layer 17 or an alloy of the same metal as the metal included in the electron injection layer 17. A metal thin film (diffusion suppression layer 15) is provided. Thereby, diffusion of the metal contained in the electron injection layer 17 into the light emitting layer 14 is suppressed by the diffusion suppression layer 15. At this time, the thickness of the diffusion suppression layer 15 is, for example, 0.1 nm or more and 2 nm or less, and since it is very thin, there is almost no possibility that the electron injection property is inhibited by the diffusion suppression layer 15, There is almost no possibility that the transmittance of light transmitted through the diffusion suppressing layer 15 is lowered. Therefore, it is possible to suppress a decrease in luminous efficiency.

  In the present embodiment, the doped metal contained in the electron transport layer 16 or the electron injection layer 17 is a transition metal such as Yb. Thereby, the diffusion suppression layer 15 itself is stable, and the metal in the diffusion suppression layer 15 is difficult to diffuse into the light emitting layer 14. Therefore, it is possible to suppress a decrease in luminous efficiency.

  In the present embodiment, the electron transport layer 16 is doped with metal. Thereby, compared with the case where the metal is not doped to the electron carrying layer 16, the applied voltage to the organic electroluminescent element 1 can be restrained low. Further, the metal doping amount of the electron transport layer 16 is smaller than the metal doping amount of the electron injection layer 17 (organic electron injection layer). Thereby, compared with the case where the same amount of metal as that of the electron injection layer 17 is doped in the electron transport layer 16, the diffusion of the doped metal into the light emitting layer 14 is reduced and the transmittance of the electron transport layer 16 is reduced. It can suppress and the fall of luminous efficiency can be suppressed. In addition, the diffusion of the doped metal into the light emitting layer 14 can be effectively suppressed by the diffusion suppressing layer 15. As a result, it is possible to suppress a decrease in light emission efficiency while keeping the drive voltage low.

  In the present embodiment, the thickness of the electron injection layer 17 is smaller than the thickness of the electron transport layer 16. The thickness of the electron transport layer 16 is, for example, greater than 15 nm, and the thickness of the electron injection layer 17 is, for example, 15 nm or less. At this time, since the electron transport layer 16 is doped with metal and has conductivity, even if the electron transport layer 16 is made thick, the influence on the driving voltage of the organic electroluminescent element 1 is small. Therefore, the electron transport layer 16 can be made thick so that the organic electroluminescent element 1 can correspond to a higher-order cavity length. Therefore, even if the organic electroluminescent element 1 is made to correspond to a higher-order cavity length. Thus, a decrease in luminous efficiency can be suppressed.

<2. Modification of First Embodiment>
[Modification A]
In the above embodiment, when the diffusion suppression layer 15 is thick, diffusion prevention functions sufficiently, but the transmittance of the diffusion suppression layer 15 is lowered, and the light emission efficiency is likely to deteriorate. Moreover, in the said embodiment, when the diffusion suppression layer 15 is made thin, diffusion prevention may not function sufficiently, but the transmittance of the diffusion suppression layer 15 is improved and the light emission efficiency is improved. Thus, the transmittance and the light emission efficiency are in a trade-off relationship. In the above embodiment, the diffusion suppression layer 15 is in direct contact with the light emitting layer 14. Therefore, quenching may occur, and the metal contained in the diffusion suppression layer 15 may slightly diffuse into the light emitting layer 14.

  Therefore, in the above embodiment, the organic electroluminescent element 1 includes, for example, a buffer layer 19 made of a conductive organic material between the light emitting layer 14 and the diffusion suppressing layer 15 as shown in FIG. May be provided. In FIG. 2, one of the hole injection layer 12 and the hole transport layer 13 may be omitted. In FIG. 2, one of the electron transport layer 16 and the electron injection layer 17 may be omitted. The buffer layer 19 may be in contact with the light emitting layer 14 or may not be in contact with the light emitting layer 14.

  The buffer layer 19 is a layer for preventing the light emitting layer 14 and the diffusion suppressing layer 15 from directly contacting each other. The buffer layer 19 is disposed between the light emitting layer 14 and the electron transport layer 16 or the electron injection layer 17, and is disposed closer to the light emitting layer 14 than the diffusion suppression layer 15. When the electron transport layer 16 is provided, the buffer layer 19 is in contact with the diffusion suppression layer 15. When the electron transport layer 16 is omitted, the buffer layer 19 is in contact with the electron injection layer 17. The buffer layer 19 may have a function as a hole blocking layer. The buffer layer 19 is made of, for example, a π-electron low molecular weight organic material such as an oxadiazole derivative (OXD), a triazole derivative (TAZ), or a phenanthroline derivative (BCP, Bphen).

  FIG. 3 conceptually shows an example of the energy level of each layer of the organic electroluminescent element 1 according to this modification.

In the layer composed of organic materials, the upper line is LUMO (lowest unoccupied molecular orbital) and the lower line is HOMO (highest occupied molecular orbital). is there. In FIG. 3, E <b> 1 is the work function of the diffusion suppression layer 15, and E <b> 2 is the LUMO energy level of the buffer layer 19. As shown in FIG. 3, E2 is deeper than E1, and E1 and E2 satisfy the following expression (1). E1 and E2 preferably further satisfy the following formula (2).
| E1-E2 |> 0 (1)
0 <| E1-E2 | <0.6 eV (2)

When E1 and E2 are too close to each other, electron orbit overlap occurs, and a metal complex may be formed in the buffer layer 19. When a metal complex is formed in the buffer layer 19, the formed metal complex may diffuse into the light emitting layer 14 and the light emission efficiency may be reduced. Therefore, the buffer layer 19 is preferably made of an organic material that does not form a metal complex even when it contacts the diffusion suppression layer 15. Also, if E1 and E2 are too close to each other, quenching is likely to occur. In addition, when E1 and E2 are too far from each other, the drive voltage of the organic electroluminescent element 1 may become too high. When the difference between E1 and E2 is 0.6 eV or more, the drive voltage of the organic electroluminescent element 1 becomes several volts, for example. Accordingly, E1 and E2 preferably satisfy the following expression (3) in order to make the drive voltage about 1 volt or less, for example, and | E1-E2 | is 0.3 eV. More preferred.
0.2 <| E1-E2 | <0.4 eV (3)

  In this modification, diffusion suppression layers 15 and 19 are provided between the light emitting layer 14 and the electron transport layer 16 or the electron injection layer 17. Accordingly, by making the diffusion suppression layer 15 relatively thin and making the diffusion suppression layer 19A relatively thick, the diffusion prevention layer 15 and 19A have a sufficiently high transmittance while sufficiently preventing diffusion. can do. In the present modification, the diffusion suppression layer 15 is not in direct contact with the light emitting layer 14, and E1 and E2 satisfy the above formula (1), formula (2), or formula (3). The possibility of quenching is low, and there is almost no possibility that the metal contained in the diffusion suppressing layer 15 diffuses into the light emitting layer 14. Therefore, it is possible to suppress a decrease in light emission efficiency while keeping the driving voltage low.

  In the present modification, for example, as shown in FIG. 4, E2 may be shallower than E1, and E1 and E2 may satisfy the above formula (1).

[Modification B]
In the said embodiment and modification A, the organic electroluminescent element 1 may be provided with the film thickness adjustment layer 22, as shown, for example in FIG. 5, FIG. The film thickness adjusting layer 22 is provided on the light emitting layer 14 side of the cathode 18. When the electron transport layer 16 and the electron injection layer 17 are provided in the organic electroluminescent element 1, the film thickness adjusting layer 22 is provided between, for example, the cathode 18 and the electron injection layer 17, and , Is in contact with the electron injection layer 17. When the electron injection layer 17 is omitted and the electron transport layer 16 is provided, the film thickness adjusting layer 22 is provided, for example, between the cathode 18 and the electron transport layer 16, and the electron transport. In contact with layer 16.

  The film thickness adjusting layer 22 is a layer for adjusting the distance between the anode 11 and the cathode 18 to be a predetermined optical path length. The film thickness adjusting layer 22 is made of, for example, a transparent conductive material such as ITO or IZO. The film thickness adjusting layer 22 is, for example, an ITO layer or an IZO layer. ITO and IZO are materials having high transparency and low resistance. The film thickness of the ITO layer or the IZO layer used for the film thickness adjusting layer 22 is, for example, a value larger than 15 nm.

  By providing the film thickness adjusting layer 22, the optical path length can be set to an arbitrary value. As a result, the light extraction efficiency can be increased. By the way, ITO layers and IZO layers are often formed by sputtering films. In that case, sputter damage occurs in the underlayer when forming the ITO layer or the IZO layer, and as a result, deterioration of the organic EL characteristics such as short circuit, leak, decrease in light emission efficiency, and increase in drive voltage occurs. Sometimes. Therefore, for example, a layer obtained by doping an organic material with a metal having a low work function is used as an underlayer for forming an ITO layer or an IZO layer, thereby suppressing sputter damage and suppressing deterioration of organic EL characteristics. Can be considered.

  In this modification, the electron transport layer 16 or the electron injection layer 17 can function as a base layer of the film thickness adjusting layer 22. Specifically, when the electron transport layer 16 or the electron injection layer 17 is made of an organic material containing a doped metal, the light extraction efficiency can be increased while suppressing the deterioration of the organic EL characteristics. A diffusion suppression layer 15 is provided between the film thickness adjusting layer 22 and the light emitting layer 14. Therefore, even when the electron transport layer 16 or the electron injection layer 17 is made of an organic material containing a doped metal, the diffusion suppression layer 15 is formed of a doped metal contained in the electron transport layer 16 or the electron injection layer 17. When the metal thin film is composed of the same metal or an alloy of the same metal as the doped metal contained in the electron transport layer 16 or the electron injection layer 17, the emission of the doped metal contained in the electron transport layer 16 or the electron injection layer 17 Diffusion to the layer 14 is suppressed by the diffusion suppression layer 15. Therefore, it is possible to suppress a decrease in light emission efficiency due to the electron transport layer 16 or the electron injection layer 17 that is the underlayer of the film thickness adjusting layer 22. As described above, in this modification, the light extraction efficiency is increased by the film thickness adjustment layer 22, the deterioration of the organic EL characteristics is suppressed by the electron transport layer 16 or the electron injection layer 17, and the light emission is performed by the diffusion suppression layer 15. A decrease in efficiency can be suppressed.

<3. Second Embodiment>
[Constitution]
FIG. 5 illustrates an example of a schematic configuration of the organic electroluminescent device 2 according to the second embodiment of the present disclosure. FIG. 6 illustrates an example of a circuit configuration of each pixel 21 provided in the organic electroluminescent device 2. The organic electroluminescent device 2 includes, for example, a display panel 20, a controller 30, and a driver 40. The driver 40 is mounted on the outer edge portion of the display panel 20. The display panel 20 has a plurality of pixels 21 arranged in a matrix. The controller 30 and the driver 40 drive the display panel 20 (the plurality of pixels 21) based on the video signal Din and the synchronization signal Tin input from the outside.

(Display panel 20)
The display panel 20 displays an image based on the video signal Din and the synchronization signal Tin input from the outside, by the active matrix driving of each pixel 21 by the controller 30 and the driver 40. The display panel 20 includes a plurality of scanning lines WSL extending in the row direction, a plurality of signal lines DTL and a plurality of power supply lines DSL extending in the column direction, and a plurality of pixels 21 arranged in a matrix. doing. The display panel 20 includes, for example, a substrate that supports each pixel 21. Examples of the substrate that supports each pixel 21 include a glass substrate or a flexible substrate.

  The scanning line WSL is used for selecting each pixel 21 and supplies a selection pulse for selecting each pixel 21 for each predetermined unit (for example, pixel row) to each pixel 21. The signal line DTL is used for supplying each pixel 21 with a signal voltage Vsig corresponding to the video signal Din, and supplies a data pulse including the signal voltage Vsig to each pixel 21. The power supply line DSL supplies power to each pixel 21.

  The plurality of pixels 21 includes, for example, a plurality of pixels 21 that emit red light, a plurality of pixels 21 that emit green light, and a plurality of pixels 21 that emit blue light. In addition, the some pixel 21 may be comprised including the some pixel 21 which emits another color (for example, white, yellow, etc.) further, for example.

  Each signal line DTL is connected to an output terminal of a horizontal selector 41 described later. For example, one signal line DTL is assigned to each pixel column. Each scanning line WSL is connected to an output end of a write scanner 42 described later. For example, one scanning line WSL is assigned to each pixel row. Each power line DSL is connected to the output terminal of the power source. For example, one power line DSL is allocated to each pixel row.

  Each pixel 21 includes, for example, a pixel circuit 21A and an organic electroluminescent element 21B. The organic electroluminescent element 21B is, for example, the organic electroluminescent element 1 of the above embodiment. At least one of the plurality of pixels 21 included in the display panel 20 has the organic electroluminescent element 1 of the above embodiment. That is, at least one of the plurality of organic electroluminescent elements 21B included in the display panel 20 is configured by the organic electroluminescent element 1 of the above embodiment. For example, each pixel 21 that emits blue light has the organic electroluminescent element 1 of the above embodiment as the organic electroluminescent element 21B.

  The pixel circuit 21A controls light emission / quenching of the organic electroluminescent element 21B. The pixel circuit 21A has a function of holding a voltage written in each pixel 21 by writing scanning described later. The pixel circuit 21A includes, for example, a drive transistor Tr1, a write transistor Tr2, and a storage capacitor Cs.

  The write transistor Tr2 controls application of the signal voltage Vsig corresponding to the video signal Din to the gate of the drive transistor Tr1. Specifically, the write transistor Tr2 samples the voltage of the signal line DTL and writes the voltage obtained by the sampling to the gate of the drive transistor Tr1. The drive transistor Tr1 is connected in series to the organic electroluminescent element 21B. The drive transistor Tr1 drives the organic electroluminescent element 21B. The drive transistor Tr1 controls the current flowing through the organic electroluminescent element 21B according to the voltage sampled by the write transistor Tr2. The holding capacitor Cs holds a predetermined voltage between the gate and source of the driving transistor Tr1. The storage capacitor Cs has a role of holding the gate-source voltage Vgs of the drive transistor Tr1 constant during a predetermined period. The pixel circuit 21A may have a circuit configuration in which various capacitors and transistors are added to the above-described 2Tr1C circuit, or may have a circuit configuration different from the above-described 2Tr1C circuit configuration.

  Each signal line DTL is connected to an output terminal of a horizontal selector 41, which will be described later, and the source or drain of the write transistor Tr2. Each scanning line WSL is connected to an output terminal of a write scanner 42 described later and a gate of the write transistor Tr2. Each power line DSL is connected to the output terminal of the power circuit 33 and the source or drain of the driving transistor Tr1.

  The gate of the writing transistor Tr2 is connected to the scanning line WSL. The source or drain of the write transistor Tr2 is connected to the signal line DTL. Of the source and drain of the write transistor Tr2, a terminal not connected to the signal line DTL is connected to the gate of the drive transistor Tr1. The source or drain of the drive transistor Tr1 is connected to the power supply line DSL. Of the source and drain of the drive transistor Tr1, a terminal not connected to the power supply line DSL is connected to the anode 11 of the organic electroluminescent element 21B. One end of the storage capacitor Cs is connected to the gate of the drive transistor Tr1. The other end of the storage capacitor Cs is connected to a terminal on the organic electroluminescent element 21B side of the source and drain of the drive transistor Tr1.

(Driver 40)
The driver 40 has, for example, a horizontal selector 41 and a write scanner 42. For example, the horizontal selector 41 applies the analog signal voltage Vsig input from the controller 30 to each signal line DTL in response to (in synchronization with) the input of the control signal. The write scanner 42 scans the plurality of pixels 21 for each predetermined unit.

(Controller 30)
Next, the controller 30 will be described. For example, the controller 30 performs a predetermined correction on the digital video signal Din input from the outside, and generates a signal voltage Vsig based on the video signal obtained thereby. For example, the controller 30 outputs the generated signal voltage Vsig to the horizontal selector 41. For example, the controller 30 outputs a control signal to each circuit in the driver 40 in response to (in synchronization with) a synchronization signal Tin input from the outside.

[effect]
In the present embodiment, at least one of the plurality of organic electroluminescent elements 21B included in the display panel 20 is configured by the organic electroluminescent element 1 of the above-described embodiment. Accordingly, it is possible to realize the organic electroluminescent device 2 with high luminous efficiency.

<4. Application example>
[Application example 1]
Below, the application example of the organic electroluminescent apparatus 2 demonstrated by the said 2nd Embodiment is demonstrated. The organic electroluminescent device 2 is a television signal, a digital camera, a notebook personal computer, a sheet-like personal computer, a mobile terminal device such as a mobile phone, or a video camera. The present invention can be applied to display devices for electronic devices in various fields that display signals as images or videos.

  FIG. 7 is a perspective view of the appearance of the electronic apparatus 3 according to this application example. The electronic device 3 is, for example, a sheet-like personal computer having a display surface 320 on the main surface of the housing 310. The electronic device 3 includes the organic electroluminescent device 2 on the display surface 320 of the electronic device 3. The organic electroluminescent device 2 is arranged so that the display panel 20 faces the outside. In this application example, since the organic electroluminescent device 2 is provided on the display surface 320, the electronic device 3 having high luminous efficiency can be realized.

[Application example 2]
Below, the application example of the organic electroluminescent element 1 demonstrated in the said 1st Embodiment is demonstrated. The organic electroluminescent element 1 can be applied to a light source of a lighting device in various fields such as a desk or floor lighting device or a room lighting device.

  FIG. 8 shows the appearance of an indoor lighting device to which the organic electroluminescent element 1 is applied. This illuminating device has the illumination part 410 comprised including the one or some organic electroluminescent element 1, for example. The illumination units 410 are arranged on the ceiling 420 of the building at an appropriate number and interval. Note that the illumination unit 410 can be installed in an arbitrary place such as a wall 430 or a floor (not shown), not limited to the ceiling 420, depending on the application.

  In these illumination devices, illumination is performed by light from the organic electroluminescent element 1. Thereby, an illuminating device with high luminous efficiency can be realized.

  While the present disclosure has been described with the embodiment and application examples, the present disclosure is not limited to the embodiment and the like, and various modifications can be made. In addition, the effect described in this specification is an illustration to the last. The effects of the present disclosure are not limited to the effects described in this specification. The present disclosure may have effects other than those described in this specification.

For example, this indication can take the following composition.
(1)
A first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode are provided in this order, and the doped metal and the organic light emitting layer are interposed between the organic light emitting layer and the organic electron transport layer. An organic electroluminescent device comprising a metal thin film composed of the same metal or an alloy of the same metal as the doped metal.
(2)
The organic electroluminescent element according to (1), wherein the doped metal is a transition metal.
(3)
The organic electroluminescent element according to (2), wherein the doped metal is Yb (ytterbium).
(4)
The thickness of the said metal thin film is 0.1 nm or more and 2 nm or less. The organic electroluminescent element as described in any one of (1) to (3).
(5)
The organic electroluminescent element according to any one of (1) to (4), further including a film thickness adjusting layer made of a transparent conductive material between the second electrode and the organic electron transport layer.
(6)
The organic electroluminescence according to any one of (1) to (4), further comprising an organic electron injection layer including the same doped metal as the doped metal between the organic electron transporting layer and the second electrode. element.
(7)
The organic electroluminescent element according to (6), wherein a metal doping amount of the organic electron transport layer is smaller than a metal doping amount of the organic electron injection layer.
(8)
The thickness of the said organic electron carrying layer is larger than 15 nm. The organic electroluminescent element as described in (6) or (7).
(9)
The thickness of the said organic electron injection layer is 15 nm or less. The organic electroluminescent element as described in any one of (6) to (8).
(10)
The organic electroluminescence according to any one of (1) to (4), further comprising an electron injection layer made of the same metal as the doped metal between the organic electron transport layer and the second electrode. element.
(11)
The thickness of the said organic electron carrying layer is larger than 15 nm. The organic electroluminescent element as described in (10).
(12)
The thickness of the said electron injection layer is 15 nm or less. The organic electroluminescent element as described in (10) or (11).
(13)
A first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order; and the doped metal between the organic light emitting layer and the organic electron injection layer, An organic electroluminescent device comprising a metal thin film composed of the same metal or an alloy of the same metal as the doped metal.
(14)
The organic electroluminescence device according to (13), wherein the doped metal is a transition metal.
(15)
The organic electroluminescent element according to (14), wherein the doped metal is Yb (ytterbium).
(16)
The thickness of the said metal thin film is 0.1 nm or more and 2 nm or less. The organic electroluminescent element as described in any one of (13) to (15).
(17)
The film thickness adjusting layer made of a transparent conductive material is further provided between the second electrode and the organic electron injecting layer. (6) to (9) and (13) to (16) Organic electroluminescent element.
(18)
The organic electroluminescence device according to any one of (10) to (12), further including a film thickness adjusting layer made of a transparent conductive material between the second electrode and the electron injection layer.
(19)
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode in this order, and further the organic light emitting An organic electroluminescent device having a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron transport layer.
(20)
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order. An organic electroluminescent device comprising a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron injection layer.
(21)
With an organic electroluminescent device,
The organic electroluminescent device is:
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode in this order, and further the organic light emitting An electronic device having a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron transport layer.
(22)
With an organic electroluminescent device,
The organic electroluminescent device is:
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order. An electronic device comprising a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron injection layer.

  DESCRIPTION OF SYMBOLS 1 ... Organic electroluminescent element, 2 ... Organic electroluminescent apparatus, 3 ... Electronic device, 10 ... Board | substrate, 11 ... Anode, 12 ... Hole injection layer, 13 ... Hole transport layer, 14 ... Light emitting layer, 15 ... Diffusion suppression 16 ... Electron transport layer, 17 ... Electron injection layer, 18 ... Cathode, 19 ... Buffer layer, 20 ... Display panel, 21 ... Pixel, 21A ... Pixel circuit, 21B ... Organic electroluminescent element, 22 ... Film thickness adjusting layer , 30 ... Controller, 40 ... Driver, 41 ... Horizontal selector, 42 ... Light scanner, 310 ... Housing, 320 ... Display surface, 410 ... Illumination unit, 420 ... Ceiling, 430 ... Wall, Cs ... Holding capacity, DTL ... Signal Line, DSL ... Power supply line, Tr1 ... Drive transistor, Tr2 ... Write transistor, Vgs ... Gate-source voltage, Vsig ... Signal voltage, WSL ... Scanning line.

Claims (22)

A first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode are provided in this order, and the doped metal and the organic light emitting layer are interposed between the organic light emitting layer and the organic electron transport layer. An organic electroluminescent device comprising a metal thin film composed of the same metal or an alloy of the same metal as the doped metal. The organic electroluminescent element according to claim 1, wherein the doped metal is a transition metal. The organic electroluminescent element according to claim 2, wherein the doped metal is Yb (ytterbium). The thickness of the said metal thin film is 0.1 nm or more and 2 nm or less, The organic electroluminescent element as described in any one of Claims 1-3. The organic electroluminescent element according to any one of claims 1 to 4, further comprising a film thickness adjusting layer made of a transparent conductive material between the second electrode and the organic electron transport layer. The organic electroluminescence according to any one of claims 1 to 4, further comprising an organic electron injection layer containing the same doped metal as the doped metal between the organic electron transport layer and the second electrode. element. The organic electroluminescent element according to claim 6, wherein a metal doping amount of the organic electron transport layer is smaller than a metal doping amount of the organic electron injection layer. The organic electroluminescent element according to claim 6 or 7, wherein a thickness of the organic electron transport layer is larger than 15 nm. The thickness of the said organic electron injection layer is 15 nm or less. The organic electroluminescent element as described in any one of Claims 6-8. 5. The organic electroluminescence according to claim 1, further comprising an electron injection layer made of the same metal as the doped metal between the organic electron transport layer and the second electrode. element. The organic electroluminescent element according to claim 10, wherein the thickness of the organic electron transport layer is greater than 15 nm. The organic electroluminescent element according to claim 10 or 11, wherein a thickness of the electron injection layer is 15 nm or less. A first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order; and the doped metal between the organic light emitting layer and the organic electron injection layer, An organic electroluminescent device comprising a metal thin film composed of the same metal or an alloy of the same metal as the doped metal. The organic electroluminescent element according to claim 13, wherein the doped metal is a transition metal. The organic electroluminescent element according to claim 14, wherein the doped metal is Yb (ytterbium). The organic electroluminescent element according to any one of claims 13 to 15, wherein a thickness of the metal thin film is 0.1 nm or more and 2 nm or less. The film thickness adjustment layer which consists of a transparent conductive material was further provided between the said 2nd electrode and the said organic electron injection layer, The Claims 6-9 and Claim 13-16. Organic electroluminescent element. The organic electroluminescent element according to claim 10, further comprising a film thickness adjusting layer made of a transparent conductive material between the second electrode and the electron injection layer. A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode in this order, and further the organic light emitting An organic electroluminescent device having a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron transport layer. A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order. An organic electroluminescent device comprising a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron injection layer. With an organic electroluminescent device,
The organic electroluminescent device is:
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron transport layer containing a doped metal, and a second electrode in this order, and further the organic light emitting An electronic device having a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron transport layer. With an organic electroluminescent device,
The organic electroluminescent device is:
A light-emitting panel having a plurality of organic electroluminescent elements;
A drive circuit for driving each of the organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements has a first electrode, an organic light emitting layer, an organic electron injection layer containing a doped metal, and a second electrode in this order. An electronic device comprising a metal thin film made of the same metal as the doped metal or an alloy of the same metal as the doped metal between the layer and the organic electron injection layer.

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