JP2018190804A - Organic electroluminescent element, organic electroluminescent device, electronic apparatus, and method of manufacturing organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element whose light emission characteristics can be easily controlled, and to provide an organic electroluminescent device, an electronic apparatus, and a method of manufacturing an organic electroluminescent element.SOLUTION: The organic electroluminescent element according to one embodiment of the present disclosure includes a first electrode, a hole transport layer, an organic light-emitting layer, an electron transport layer, and a second electrode in this order. The organic light-emitting layer contains host materials and dopant materials. The concentrations of all the dopant materials contained in the organic light-emitting layer are high on the hole transport layer side and low on the electron transport layer side.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to an organic electroluminescent element, an organic electroluminescent device, an electronic apparatus, and a method for manufacturing the organic electroluminescent element.

  Various types of organic electroluminescent devices (organic electroluminescent displays) using organic electroluminescent elements have been proposed (see, for example, Patent Document 1).

JP 2006-157799 A JP 2011-009205 A JP 2014-225710 A

  By the way, in the organic electroluminescent device, it is not easy to control the light emission characteristics of the organic electroluminescent element. Therefore, it is desirable to provide an organic electroluminescent element, an organic electroluminescent device, an electronic apparatus, and a method for manufacturing the organic electroluminescent element that can easily control the light emission characteristics.

  The organic electroluminescent element of one embodiment of the present disclosure includes a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order. The organic light emitting layer contains a host material and a dopant material, and the concentration of all the dopant materials contained in the organic light emitting layer is high on the hole transport layer side and low on the electron transport layer side.

  An organic electroluminescent device according to an embodiment of the present disclosure includes a plurality of organic electroluminescent elements. In this organic electroluminescent device, at least one of the plurality of organic electroluminescent elements has the same components as the above organic electroluminescent elements.

  An electronic apparatus according to an embodiment of the present disclosure includes an organic electroluminescent device. The organic electroluminescent device in this electronic apparatus has the same components as the above organic electroluminescent device.

  The manufacturing method of the 1st organic electroluminescent element of one Embodiment of this indication is equipped with the 1st electrode, the positive hole transport layer, the organic light emitting layer, the electron carrying layer, and the 2nd electrode in this order, and is organic. It is a manufacturing method of the organic electroluminescent element in which a light emitting layer contains host material and dopant material. This manufacturing method includes a step of forming the organic light emitting layer by multiple times of vapor deposition so that the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side.

  The manufacturing method of the 2nd organic electroluminescent element of one embodiment of this indication is provided with the 1st electrode, the positive hole transport layer, the organic light emitting layer, the electron carrying layer, and the 2nd electrode in this order, and is organic. It is a manufacturing method of the organic electroluminescent element in which a light emitting layer contains host material and dopant material. In this manufacturing method, an organic light emitting layer is formed by coating, and the organic light emitting layer is formed at a drying speed adjusted so that the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side. Process.

  According to the organic electroluminescent device, the organic electroluminescent device, the electronic device, the first organic electroluminescent device manufacturing method, and the second organic electroluminescent device manufacturing method according to an embodiment of the present disclosure, the organic light emitting device includes Since the concentration of all dopant materials is high on the hole transport layer side and low on the electron transport layer side, the light emission characteristics of the organic electroluminescent element can be easily controlled. 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 an example of concentration distribution of the dopant material in the light emitting layer of FIG. 1, and the position of a light emission area | region. It is a figure showing an example of concentration distribution of the dopant material in the light emitting layer of the organic electroluminescent element which concerns on a comparative example, and the position of a light emission area | region. It is a figure showing an example of concentration distribution of the dopant material in the light emitting layer of the organic electroluminescent element which concerns on a comparative example, and the position of a light emission area | region. It is a figure showing an example of the manufacturing procedure of the light emitting layer of FIG. It is a figure showing an example of concentration distribution of the dopant material in the light emitting layer of FIG. 1, and the position of a light emission area | region. It is a figure showing an example of the manufacture procedure of the light emitting layer of FIG. It is a figure showing an example of schematic structure of an organic electroluminescent device concerning a 2nd embodiment of this indication. It is a figure showing an example of the circuit structure of the pixel 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. Second embodiment (organic electroluminescence device)
3. 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 13 and a hole transport layer 12 and an electron transport layer 14 disposed so as to sandwich the light emitting layer 13. The hole transport layer 12 is provided on the hole injection side of the light emitting layer 13, and the electron transport layer 14 is provided on the electron injection side of the light emitting layer 13. The organic electroluminescent element 1 has an element structure including, for example, an anode 11, a hole transport layer 12, a light emitting layer 13, an electron transport layer 14, and a cathode 15 in this order from the substrate 10 side. In the organic electroluminescent element 1, other functional layers (for example, a hole injection layer, an electron injection layer, etc.) may be included.

  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, and 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 transport layer 12 has a function of transporting holes injected from the anode 11 to the light emitting layer 13. The hole transport layer 12 is a coating film, and is formed, for example, by applying and drying a solution containing the hole transport material 12M as a solute. That is, the hole transport layer 12 includes the hole transport material 12M. Moreover, the hole transport material 12M which is a solute has a function of insolubilizing. The insolubilizing function refers to a function in which an insolubilizing group such as a crosslinkable group or a heat dissociable soluble group undergoes a chemical change by irradiation with heat or ultraviolet light or a combination thereof, and insolubilizes in an organic solvent or water. Therefore, the hole transport layer 12 is an insolubilized hole transport layer.

  The hole transport layer 12 is composed of a hole transport material 12M having a function of insolubilization. The hole transporting material 12M which is a raw material (material) of the hole transporting layer 12 is, for example, an arylamine derivative, a triazole derivative, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative and a pyrazolone derivative, phenylenediamine Derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, butadiene compounds, polystyrene derivatives, hydrazone derivatives, triphenylmethane derivatives, tetraphenylbenzine derivatives, etc., or a combination thereof Material. The hole transporting material 12M further has, for example, a soluble group, a crosslinkable group, or a thermally dissociable soluble group in its molecular structure for the function of solubility and insolubilization.

  The light emitting layer 13 has a function of emitting light of a predetermined color by recombination of holes and electrons. The light emitting layer 13 is a coating film, and is formed, for example, by applying and drying a solution containing the organic light emitting material 13M as a solute. The solution containing the organic light emitting material 13M as a solute is configured to include, for example, the organic light emitting material 13M and a solvent. The light emitting layer 13 is a layer that emits light by generating excitons by recombining holes injected from the anode 11 and electrons injected from the cathode 15 in the light emitting layer 13. The light emitting layer 13 is, for example, a blue light emitting layer made of a blue organic light emitting material. The organic light emitting material 13M that is a raw material (material) of the light emitting layer 13 includes a host material and a dopant material. The host material mainly has the function of transporting electrons or holes, and the dopant material has the function of light emission. Each of the host material and the dopant material included in the organic light emitting material 13M is not limited to only one type, and may be a combination of two or more types.

  As a host material of the light emitting layer 13, 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 dopant material of the light emitting layer 13, 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. In addition, a metal complex may be used as the dopant material of the light emitting layer 13. 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 light emitting layer 13 is made of an organic light emitting material having a hole mobility larger than the electron mobility. That is, the light emitting layer 13 is a layer made of a material having a high hole transporting property, and has a hole mobility larger than the electron mobility. The material constituting the hole transport layer 12 and the electron transport layer 14 is made of a material corresponding to the material constituting the light emitting layer 13.

  The electron transport layer 14 has a function of transporting electrons injected from the cathode 15 to the light emitting layer 13. The electron transport layer 14 is a vapor deposition film. The electron transport layer 14 is made of, for example, an organic material having an electron transport property (hereinafter referred to as “electron transport material 14M”). The electron transport layer 14 is made of an organic material having a wide energy gap suitable for preventing hole blocking and exciton deactivation. The electron transport layer 14 is made of an organic material in which the energy gap of the electron transport layer 14 is larger than the energy gap of the light emitting layer 13.

  The energy gap refers to an energy difference between a HOMO (highest occupied molecular orbital) energy level and a LUMO (lowest unoccupied molecular orbital) energy level. The energy gap is also called a band gap. Examples of the method for measuring the HOMO level include atmospheric photoelectron spectroscopy, electrochemical techniques (cyclic voltammetry), and photoelectron spectroscopy (PES). On the other hand, examples of the LUMO level measurement method include inverse photoelectron spectroscopy (IPES), a method of calculating from the energy gap obtained from the absorption edge by light absorption spectroscopy and the HOMO level. In addition, a method of calculating the HOMO level and the LUMO level rank for each level using molecular activation method calculation may be used.

  The electron transport layer 14 is interposed between the light emitting layer 13 and the cathode 15 and has a function of transporting electrons injected from the cathode 15 to the light emitting layer 13. Note that the electron transport layer 14 further has a charge blocking function for suppressing penetration of charges (holes in the present embodiment) from the light emitting layer 13 to the cathode 15 and a function for suppressing quenching of the excited state of the light emitting layer 13. Etc. are preferable. The electron transporting material 14M that is a raw material (material) of the electron transport layer 14 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 electron transport layer 14 may include a metal having an electron transport property. The electron transport layer 14 can improve the electron transport property of the electron transport layer 14 by containing the metal which has electron transport property. Examples of the metal contained in the electron transport layer 14 include barium (Ba), lithium (Li), calcium (Ca), potassium (K), cesium (Cs), sodium (Na), and rubidium (Rb). be able to.

  The cathode 15 is a reflective electrode having light reflectivity, for example, a metal electrode formed using a metal material having reflectivity. As the material of the cathode 15, for example, aluminum (Al), magnesium (Mg), silver (Ag), an aluminum-lithium alloy, a magnesium-silver alloy, or the like is used. The cathode 15 is not limited to the reflective electrode, and may be a transparent electrode such as an ITO film, like the anode 11. In the present embodiment, since the substrate 10 and the anode 11 are translucent and the cathode 15 is reflective, the organic electroluminescent element 1 has a bottom emission structure in which light is emitted from the substrate 10 side. The organic electroluminescent element 1 is not limited to the bottom emission structure, and may have a top emission structure.

  Next, the characteristics of the organic electroluminescent element 1 according to the present embodiment will be described with reference to a comparative example. FIG. 2 shows an example of the concentration distribution of the dopant material in the light emitting layer 13 and the position of the light emitting region. The concentration distribution of the dopant material and the position of the light emitting region in the light emitting layer 13 are not limited to those in FIG. 3 and 4 show examples of the concentration distribution of the dopant material and the position of the light emitting region in the light emitting layer of the organic electroluminescent element according to the comparative example.

  The light emitting region refers to the distribution of excitons generated in the light emitting layer in the light emitting layer. 2 to 4, the light emitting layer is divided in the middle, and is divided into two equal parts: a region on the side where the hole transport layer is disposed and a region on the side where the electron transport layer is disposed. In FIG. 2, the concentration of all the dopant materials contained in the light emitting layer 13 is high on the hole transport layer 12 side and low on the electron transport layer 14 side. 3 and 4, the concentration of all dopant materials contained in the light emitting layer 13 is constant regardless of the position in the light emitting layer 13.

  In FIG. 2, the light emitting layer 13 has a light emitting region on the electron transport layer 14 side in the light emitting layer 13. In FIG. 2, all dopant materials contained in the light emitting layer 13 have a concentration distribution such that the position of the light emitting region is on the electron transport layer 14 side in the light emitting layer 13. In FIG. 3, the light emitting layer according to the comparative example has a light emitting region on the hole transport layer side in the light emitting layer. In FIG. 4, the light emitting layer according to the comparative example has a light emitting region on the electron transport layer side in the light emitting layer.

  “The light emitting region is on the electron transport layer side” means that, for example, 50% or more of the light emitting region in the light emitting layer exists in the region on the side where the electron transport layer is disposed. That is, “the light emitting region is on the electron transport layer side” includes “the light emitting region is located near the interface with the electron transport layer”. “The light emitting region is on the hole transport layer side” means, for example, that 50% or more of the light emitting region in the light emitting layer exists in the region on the side where the hole transport layer is disposed. Yes. That is, “the light emitting region is on the hole transport layer side” also includes “the light emitting region is located near the interface with the electron transport layer”. In FIG. 2, the peak of the light emitting region may be located at the interface of the light emitting layer 13 or may be located within the light emitting layer 13.

  2 to 4 indicate the difference between the HOMO energy level E1 of the dopant material and the HOMO energy level E2 of the host material in the light-emitting layer 13. In both of the present embodiment and the comparative example, ΔE is a value larger than 0.4 eV (for example, 0.6 eV or more). When ΔE is larger than 0.4 eV, the dopant material in the light emitting layer 13 has a function of trapping holes in the carrier recombination region (light emitting region) in the light emitting layer 13.

  Dc in FIGS. 2 to 4 indicates a minimum value (for example, a value larger than 10%) of the concentration of the dopant material with respect to the host material, in which the dopant material in the light emitting layer exhibits carrier transport ability. In the region where the concentration of the dopant material with respect to the host material is Dc or more, the dopant material in the light emitting layer exhibits carrier transport ability. Therefore, in a region where the concentration of the dopant material with respect to the host material is less than Dc, the dopant material in the light emitting layer does not exhibit carrier transport ability. At this time, when ΔE is larger than 0.4 eV, a region where the concentration of the dopant material with respect to the host material is less than Dc is a light emitting region.

  In FIG. 2, in the entire region of the light emitting layer 13 on the hole transport layer 12 side, the concentration Dd1 of all dopant materials with respect to the host material is greater than or equal to Dc. In FIG. 2, the concentration Dd2 of all dopant materials with respect to the host material is less than Dc in at least the boundary with the electron transport layer 14 in the region of the light emitting layer 13 on the electron transport layer 14 side. Yes. Accordingly, in FIG. 2, at least a boundary portion with the electron transport layer 14 in the region on the electron transport layer 14 side of the light emitting layer 13 is a light emitting region. In the present embodiment, the concentration Dd2 with respect to the host material of all dopant materials may be less than Dc in at least a part of the region on the electron transport layer 14 side of the light emitting layer 13.

  In FIG. 3, the concentration Dd of all dopant materials with respect to the host material is less than Dc in all regions in the light emitting layer. Therefore, in FIG. 3, since the dopant material in the light emitting layer does not show carrier transporting ability, the region on the hole transporting layer side of the light emitting layer becomes the light emitting region. In FIG. 4, the concentration Dd of all dopant materials with respect to the host material in all regions in the light emitting layer is greater than or equal to Dc. Therefore, in FIG. 4, since the dopant material in the light emitting layer exhibits carrier transport ability, holes are not trapped by the dopant material in the light emitting layer, and the boundary of the light emitting layer on the electron transport layer side becomes the light emitting region.

  2 to 4 indicate the minimum concentration (Dc is also a large value) of the dopant material relative to the host material when concentration quenching occurs. In the region where the concentration of the dopant material with respect to the host material is Dq or more, concentration quenching occurs. Therefore, concentration quenching does not occur in the region where the concentration of the dopant material with respect to the host material is less than Dq. In FIG. 2, concentration quenching does not occur because there is no light emitting region in the region where the concentration of the dopant material with respect to the host material is Dq or higher. 3 and 4, there is no region where the concentration of the dopant material with respect to the host material is equal to or higher than Dq, and therefore concentration quenching does not occur.

[Production method]
Next, the manufacturing method of the light emitting layer 13 of the organic electroluminescent element 1 of this Embodiment is demonstrated. FIG. 5 shows an example of the manufacturing procedure of the light emitting layer 13. A light emitting layer 13 ′ is formed on the hole transport layer 12 by a coating method using a solution containing the organic light emitting material 13M as a solute (step S101). Next, the light emitting layer 13 ′ is dried at a predetermined drying speed to form the light emitting layer 13 having a predetermined concentration distribution (step S102). Here, the predetermined drying rate refers to a drying rate adjusted so that the concentration of all dopant materials in the light emitting layer 13 is high on the hole transport layer 12 side and low on the electron transport layer 14 side. .

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

  In recent years, attention has been paid to forming an organic light-emitting layer or the like by coating with a simple manufacturing process and easy area enlargement. When forming an organic light emitting layer or the like by coating, it is necessary to insolubilize the underlayer, for example. When the hole transport layer as the underlayer is also formed by coating, for example, there is a method of using a material having a function of insolubilizing as a material constituting the hole transport layer. However, when a material with solubility and insolubilization functions is used in the hole transport layer, the material with solubility and insolubilization functions has a soluble group, bridging group, and thermal dissociation in its molecular structure. Since soluble groups are incorporated in the molecular structure, conjugation is widened and the energy gap is narrowed. Therefore, there is a problem that the device performance is deteriorated particularly in the blue organic electroluminescent device.

  On the other hand, in this Embodiment, the density | concentration of all the dopant materials contained in the light emitting layer 13 is high at the hole transport layer 12 side, and is low at the electron transport layer 14 side. Thereby, since the light emitting region in the light emitting layer 13 is on the electron transport layer 14 side, deactivation by the hole transport layer 12 hardly occurs. Therefore, even if it is the coating type organic electroluminescent element which formed the positive hole transport layer 12 which is a coating film, and the light emitting layer 13 which is a coating film, the fall of element performance can be suppressed.

  In the present embodiment, all dopant materials contained in the light emitting layer 13 function as hole traps in the light emitting region and function as hole transport in regions other than the light emitting region. Therefore, since these functions can be realized with the same material, the light emitting layer 13 can be configured with a simple layer configuration.

  Moreover, in this Embodiment, the area | region where the density | concentration of all the dopant materials contained in the light emitting layer 13 is high exists in areas other than a light emitting area. Thereby, since quenching in the light emitting region does not occur, the light emission efficiency can be increased.

  In the present embodiment, for example, by adjusting the drying speed in the coating method, the concentration of all dopant materials contained in the light emitting layer 13 is high on the hole transport layer 12 side and low on the electron transport layer 14 side. can do. Therefore, the light emission characteristics of the organic electroluminescent element 1 can be easily controlled.

  In the present embodiment, the light emitting layer 13 has a light emitting region on the electron transport layer 14 side in the light emitting layer 13. Thereby, the deactivation by the hole transport layer 12 hardly occurs. Therefore, even if it is the coating type organic electroluminescent element which formed the positive hole transport layer 12 which is a coating film, and the light emitting layer 13 which is a coating film, the fall of element performance can be suppressed.

  In the present embodiment, all dopant materials in the light emitting layer 13 have a concentration distribution such that the position of the light emitting region is on the electron transport layer 14 side in the light emitting layer 13. Such a concentration distribution can be realized, for example, by adjusting the drying speed in the coating method. Therefore, the light emission characteristics of the organic electroluminescent element 1 can be easily controlled.

  In the present embodiment, ΔE is a value larger than 0.4 eV. Thereby, since the dopant material in the light emitting layer 13 has a function of trapping holes in the light emitting region, light can be emitted on the electron transport layer 14 side in the light emitting layer 13. As a result, deactivation due to the hole transport layer 12 is difficult to occur. Therefore, even if it is the coating type organic electroluminescent element which formed the positive hole transport layer 12 which is a coating film, and the light emitting layer 13 which is a coating film, the fall of element performance can be suppressed.

<2. Modification of First Embodiment>
In the said embodiment, the light emitting layer 13 was formed using the apply | coating method. However, for example, in the above embodiment, the light emitting layer 13 may be formed by using a vapor deposition method.

  FIG. 6 shows an example of the concentration distribution of the dopant material and the position of the light emitting region in the light emitting layer 13 according to this modification. The concentration distribution of the dopant material and the position of the light emitting region in the light emitting layer 13 according to this modification are not limited to those in FIG. In the light emitting layer 13 illustrated in FIG. 6, the change in the concentration distribution is steep compared to the light emitting layer 13 illustrated in FIG. 2. The light emitting layer 13 shown in FIG. 6 is composed of two vapor deposition layers 13a and 13b with a boundary where a change in concentration distribution is steep. Here, the vapor deposition layer 13 a is on the hole transport layer 12 side in the light emitting layer 13, and the vapor deposition layer 13 b is on the electron transport layer 14 side in the light emitting layer 13.

[Production method]
Next, a method for manufacturing the light emitting layer 13 according to this modification will be described. FIG. 7 shows an example of a manufacturing procedure of the light emitting layer 13 according to this modification. The light emitting layer 13 is formed by vapor deposition with an evaporation source adjusted so that the concentration of all dopant materials in the light emitting layer 13 is high on the hole transport layer 12 side and low on the electron transport layer 14 side. Specifically, first, the evaporation source control plate is adjusted on the hole transport layer 12 so that the concentration of all dopant materials in the light emitting layer 13 is relatively high, and the light emitting layer 13a is formed by vapor deposition. Is formed (step S201). Next, the evaporation source control plate is adjusted on the light emitting layer 13a so that the concentration of all the dopant materials in the light emitting layer 13 is relatively low, and the light emitting layer 13b is formed by vapor deposition (step S202). ).

[effect]
Next, the effect of the organic electroluminescent element 1 according to this modification will be described. In this modification, for example, by adjusting the control plate of the evaporation source in the vapor deposition method, the concentration of all dopant materials contained in the light emitting layer 13 is high on the hole transport layer 12 side and low on the electron transport layer 14 side. can do. Therefore, the light emission characteristics of the organic electroluminescent element 1 can be easily controlled.

<3. Second Embodiment>
[Constitution]
FIG. 8 illustrates an example of a schematic configuration of the organic electroluminescent device 2 according to the second embodiment of the present disclosure. FIG. 9 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 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 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. For example, each pixel 21 that emits red light and each pixel 21 that emits green light includes an organic light emitting layer 113 in place of the light emitting layer 13 in the organic electroluminescent element 1 of the above embodiment as the organic electroluminescent element 21B. You may have what was provided.

  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.

<3. 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. 10 is a perspective view of the appearance of the electronic device 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. 11 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, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode are provided in this order,
The organic light emitting layer includes a host material and a dopant material,
The organic electroluminescent element in which the concentration of all the dopant materials contained in the organic light emitting layer is high on the hole transport layer side and low on the electron transport layer side.
(2)
The organic electroluminescent element according to (1), wherein the organic light emitting layer has a light emitting region on the electron transport layer side in the organic light emitting layer.
(3)
The organic electroluminescent element according to (2), wherein the dopant material has a concentration distribution such that a position of the light emitting region is on the electron transport layer side in the organic light emitting layer.
(4)
In the said organic light emitting layer, the said host material and the said dopant material satisfy | fill the following relationship. The organic electroluminescent element as described in any one of (1) thru | or (3).
E1-E2> 0.4 eV
E1: HOMO energy level of the host material E2: HOMO energy level of the dopant material (5)
Comprising a plurality of organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements is:
Having a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order;
The organic light emitting layer includes a host material and a dopant material,
In the organic light emitting layer, the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side.
(6)
Comprising an organic electroluminescent device having a plurality of organic electroluminescent elements;
At least one of the plurality of organic electroluminescent elements is:
A first electrode;
A hole transport layer composed of a coating film;
An organic light emitting layer composed of a coating film;
An electron transport layer;
Having the second electrode in this order,
The organic light emitting layer includes a host material and a dopant material,
In the organic light emitting layer, the host material and the dopant material satisfy the following relationship.
(7)
A method for producing an organic electroluminescent device comprising a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order, wherein the organic light emitting layer includes a host material and a dopant material. There,
The manufacturing method of an organic electroluminescent element including the process of forming the said organic light emitting layer by vapor deposition which adjusted the evaporation source so that the density | concentration of the said dopant material might be high on the said positive hole transport layer side, and low on the said electron transport layer side.
(8)
A method for producing an organic electroluminescent device comprising a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order, wherein the organic light emitting layer includes a host material and a dopant material. There,
The organic light emitting layer is formed by coating, and the organic light emitting layer is formed at a drying speed adjusted so that the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side. The manufacturing method of an organic electroluminescent element including a process.

  DESCRIPTION OF SYMBOLS 1 ... Organic electroluminescent element, 2 ... Organic electroluminescent apparatus, 3 ... Electronic device, 10 ... Board | substrate, 11 ... Anode, 12, 112 ... Hole transport layer, 12M ... Hole transport material, 13, 113 ... Light emitting layer , 13A, 113A ... light emitting region, 13M ... organic light emitting material, 14, 114 ... electron transport layer, 14M ... electron transport material, 15 ... cathode, 20 ... display panel, 21 ... pixel, 21A ... pixel circuit, 21B ... organic Electroluminescent device 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, E1, E2, E3, E4, E11, E12, E13, E14 ... energy level, Tr1 ... drive transistor, Tr2 ... write transistor, Vg ... gate - source voltage, Vsig ... signal voltage, WSL ... scanning lines, ΔE, ΔE '... energy gap.

Claims (8)

A first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode are provided in this order,
The organic light emitting layer includes a host material and a dopant material,
The organic electroluminescent element in which the concentration of all the dopant materials contained in the organic light emitting layer is high on the hole transport layer side and low on the electron transport layer side. The organic electroluminescent element according to claim 1, wherein the organic light emitting layer has a light emitting region on the electron transport layer side in the organic light emitting layer. The organic electroluminescent element according to claim 2, wherein the dopant material has a concentration distribution such that a position of the light emitting region is on the electron transport layer side in the organic light emitting layer. The organic electroluminescent element according to claim 1, wherein the host material and the dopant material satisfy the following relationship in the organic light emitting layer.
E1-E2> 0.4 eV
E1: HOMO energy level of the host material E2: HOMO energy level of the dopant material Comprising a plurality of organic electroluminescent elements,
At least one of the plurality of organic electroluminescent elements is:
Having a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order;
The organic light emitting layer includes a host material and a dopant material,
In the organic light emitting layer, the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side. Comprising an organic electroluminescent device having a plurality of organic electroluminescent elements;
At least one of the plurality of organic electroluminescent elements is:
A first electrode;
A hole transport layer composed of a coating film;
An organic light emitting layer composed of a coating film;
An electron transport layer;
Having the second electrode in this order,
The organic light emitting layer includes a host material and a dopant material,
In the organic light emitting layer, the host material and the dopant material satisfy the following relationship. A method for producing an organic electroluminescent device comprising a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order, wherein the organic light emitting layer includes a host material and a dopant material. There,
The manufacturing method of an organic electroluminescent element including the process of forming the said organic light emitting layer by vapor deposition which adjusted the evaporation source so that the density | concentration of the said dopant material might be high on the said positive hole transport layer side, and low on the said electron transport layer side. A method for producing an organic electroluminescent device comprising a first electrode, a hole transport layer, an organic light emitting layer, an electron transport layer, and a second electrode in this order, wherein the organic light emitting layer includes a host material and a dopant material. There,
The organic light emitting layer is formed by coating, and the organic light emitting layer is formed at a drying speed adjusted so that the concentration of the dopant material is high on the hole transport layer side and low on the electron transport layer side. The manufacturing method of an organic electroluminescent element including a process.

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