WO2012172883A1

WO2012172883A1 - Method for manufacturing organic electroluminescent element

Info

Publication number: WO2012172883A1
Application number: PCT/JP2012/061727
Authority: WO
Inventors: 敦今村
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2011-06-14
Filing date: 2012-05-08
Publication date: 2012-12-20
Also published as: JPWO2012172883A1; JP5862665B2

Abstract

Provided is a method for manufacturing an organic electroluminescent element, whereby an organic electroluminescent element having excellent power efficiency and long service life can be obtained. In a method for manufacturing an organic electroluminescent element, a light emitting layer of the organic electroluminescent element is formed by depositing the organic compound on a substrate from a plurality of deposition sources. The method is characterized in that 1) the deposition sources are respectively filled with a host compound and a dopant compound, 2) the deposition sources respectively have different mass ratios of the dopant compound to the host compound, and 3) regions where deposition areas of the deposition sources overlap on the substrate are 10 % or more of the total deposition area.

Description

Method for manufacturing organic electroluminescence device

The present invention relates to a method for producing an organic electroluminescent element having a plurality of phosphorescent dopants having different emission wavelengths in a light emitting layer, particularly a white light emitting organic electroluminescent element.

An organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer and recombines them to exciton (exciton). ) And emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated. This organic electroluminescence device can emit light at a voltage of several volts to several tens of volts, and is a self-luminous type, so it has a wide viewing angle, high visibility, and is a thin film type solid state device. Currently, it is attracting attention from the viewpoint of space saving and portability.

However, as a problem when the organic electroluminescence element is put to practical use as a light source for illumination or a backlight of a display, improvement of light emission efficiency and light emission life, particularly improvement of light emission life can be cited as an important problem.

Generally, among blue light emitting dopants used as light emitting dopants in the light emitting layer, there are substances having a high hole transporting property. Therefore, when a blue light emitting dopant with high hole transportability is used for the light emitting layer and the blue light emitting dopant concentration in the vicinity of the anode side interface is set high, the holes are quickly separated from the anode side interface and enter the center of the light emitting layer. Will move. As a result, the center of the light emitting layer is the place where holes and electrons come into contact and emit light. It is known that a loss of light emission is large near the interface with the adjacent layer, and it is advantageous to emit light at the center of the light emitting layer far from the interface in terms of setting the light emission efficiency high.

On the other hand, at the cathode side interface, the blue light emitting dopant having a high hole transporting property acts as an electron blocking material for preventing the intrusion of electrons, so that the concentration of the blue light emitting dopant near the cathode side interface is lowered and electrons can easily enter. By doing so, electrons move away from the anode-side interface quickly to the center of the light-emitting layer, and light is emitted at the center of the light-emitting layer away from the interface.

Therefore, in the light emitting layer, the concentration of the blue light emitting dopant near the anode side interface is increased and the concentration of the blue light emitting dopant near the cathode side interface has a low concentration gradient. Since it emits light, it leads to the improvement of luminous efficiency and luminous lifetime, especially the luminous lifetime.

Conversely, when a material having a high electron transport property is used for the blue light emitting dopant, the same effect can be obtained by increasing the concentration of the blue light emitting dopant in the vicinity of the cathode side interface of the light emitting layer.

As described above, in order to solve the problems of chromaticity stability, luminous efficiency and luminous lifetime improvement, in particular, luminous lifetime enhancement, the concentration of the blue luminous dopant having a high hole transporting property on the anode interface side of the luminous layer. Is required to have a concentration gradient so that the concentration becomes lower toward the cathode interface side.

The concentration gradient of the blue light emitting dopant is preferably formed over the entire light emitting layer, and green, red, and host are preferably distributed over the entire light emitting layer. In this case, it is required that the dopant concentrations of green and red are low and evenly distributed compared to blue.

Incidentally, as a method for forming the light emitting layer, generally, there are methods such as vapor deposition, coating, and transfer, but vapor deposition is preferably used. As a vapor deposition apparatus using a vapor deposition method, a technique capable of co-vapor deposition using a plurality of materials by laminating a plurality of dispersion containers having discharge ports for discharging a vapor deposition material is disclosed (for example, Patent Documents). 1). According to the technique described in Patent Document 1, the in-plane variation in film formation can be reduced. However, in the vapor deposition apparatus described in Patent Document 1, it is difficult to perform vapor deposition so as to have a concentration gradient with high accuracy.

On the other hand, as a co-evaporation method having a concentration gradient, a technique in which two types of vapor deposition sources are arranged in the substrate conveyance direction, and the two vapor deposition sources are arranged in the substrate conveyance direction. In addition, a technique is disclosed in which the aperture diameter of each vapor deposition source is changed so that one is increased and the other is decreased along the conveyance direction (see, for example, Patent Document 2). However, in the vapor deposition apparatus described in Patent Document 2, 1) a technique for uniformly co-depositing at a low concentration is not shown, and 2) a host compound and a blue light emitting dopant are emitted from independent vapor deposition sources. It is difficult to obtain a desired concentration gradient, and 3) there are problems such as a concentration gradient not being possible with a plurality of dopants.

On the other hand, an organic electroluminescence element having a plurality of stacked layers and an overlap layer in which each constituent material of adjacent layers has a continuous concentration gradient is disclosed between the layers (see, for example, Patent Document 3). .) According to Patent Document 3, by forming an overlap layer between each layer, the constituent material concentration does not become discontinuous at the layer interface with each layer. As a result, the layer interface where the overlap layer is formed Therefore, it is said that it is possible to improve the lifetime and reliability of the device without easily accumulating charges locally or deteriorating the flow of electrons. However, the invention described in Patent Document 3 is an invention corresponding to a color display, and a white light emitting element cannot be formed. The invention described in Patent Document 3 is a method in which only one kind of material is filled in the vapor deposition source, and co-evaporation cannot be performed, and a gradient concentration structure that continuously changes the dopant concentration is formed. Can not do it.

Further, in a vapor deposition method for forming a vapor deposition layer on a substrate, a plurality of vapor deposition sources are arranged, and an angle with respect to a horizontal direction of at least one vapor deposition molecule generation surface of the vapor deposition source is different from an angle of a vapor deposition molecule generation surface of another vapor deposition source. A vapor deposition method characterized by being different is disclosed (for example, see Patent Document 4). According to the invention described in Patent Document 4, for example, even if foreign matter exists on the substrate, vapor deposition molecules are radiated from an oblique angle, and the vapor deposition film is formed so as to wrap the foreign matter without gaps. Therefore, the anode and the cathode formed with the vapor deposition film sandwiched by foreign substances are not in direct contact with each other, and the lifetime, luminous efficiency and quality of the display device can be improved by preventing the light emitting failure of the element. It is supposed to be possible. However, in Patent Document 4, there is no description or suggestion that the concentration of the constituent elements of the deposited film is continuously changed to adopt the inclined structure.

JP 2008-075095 A JP 2003-077662 A Japanese Patent Laid-Open No. 2003-077656 JP 2007-100132 A

The present invention has been made in view of the above-described problems, and its purpose is to combine a host compound, a blue light-emitting dopant with a concentration gradient, a green light-emitting dopant with a low concentration uniform distribution, and a red light-emitting dopant when forming a light-emitting layer by vapor deposition. An object of the present invention is to provide a method for producing an organic electroluminescent element capable of forming an emissive layer by vapor deposition, obtaining an organic electroluminescent element having excellent power efficiency and a long driving life.

The above object of the present invention is achieved by the following configuration.

1. In the method of manufacturing an organic electroluminescent element, the organic compound is deposited from a plurality of vapor deposition sources filled with the organic compound on the moving substrate to form a light emitting layer of the organic electroluminescent element.
1) Each of the plurality of vapor deposition sources is filled with a host compound and a dopant compound,
2) The plurality of vapor deposition sources have different mass ratios of the dopant compound to the host compound,
3) The area where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate is 10% or more of the total vapor deposition area,
The manufacturing method of the organic electroluminescent element characterized by these.

2. 2. The method for producing an organic electroluminescence element according to 1 above, wherein the dopant compounds filled in the plurality of vapor deposition sources are all the same.

3. 3. The method for producing an organic electroluminescent element according to 1 or 2, wherein the host compounds filled in the plurality of vapor deposition sources are all the same.

4. At least one of the said vapor deposition sources contains a several dopant compound, The manufacturing method of the organic electroluminescent element of any one of said 1 to 3 characterized by the above-mentioned.

5. The dopant compound is a blue light emitting dopant, a green light emitting dopant, and a red light emitting dopant, and the concentration of the blue light emitting dopant in the plurality of vapor deposition sources is different, and the blue light emitting dopant has a gradient concentration in the thickness direction in the light emitting layer. 5. The method for producing an organic electroluminescent element according to any one of 1 to 4, wherein the organic electroluminescent element is provided.

6. The dopant compound is a blue light-emitting dopant, a green light-emitting dopant, and a red light-emitting dopant, and the concentrations of the green light-emitting dopant and the red light-emitting dopant in the plurality of vapor deposition sources are equal, and the green light-emitting dopant and the red light-emitting in the light-emitting layer. 6. The method for producing an organic electroluminescent element according to any one of 1 to 5, wherein the dopant concentration is uniform in the thickness direction.

7. 7. The method of manufacturing an organic electroluminescent element according to any one of 1 to 6, wherein a surface of the vapor deposition source with respect to a discharge normal is non-parallel to the substrate surface.

8. 8. The method of manufacturing an organic electroluminescent element according to any one of 1 to 7, wherein an intersection point on a substrate where a discharge normal line of the plurality of vapor deposition sources and a substrate surface intersect with each other is different. .

According to the method of manufacturing an organic electroluminescence device of the present invention, the concentration gradient material has a concentration gradient in the thickness direction of the vapor deposition member, and the concentration uniform material is vapor deposited on the vapor deposition member with a uniform in-plane concentration distribution. can do. Therefore, for example, when a blue light emitting dopant is used as the concentration gradient material and a red light emitting dopant and a green light emitting dopant are used as the concentration uniforming material, the blue light emitting dopant can have a high concentration concentration gradient. The blue light emitting dopant concentration is increased at the anode side interface of the light emitting layer, so that the hole transport property can be further increased, and light emission at the center of the light emitting layer leads to improvement in light emission efficiency and life.

As a result, it is possible to provide a method for producing an organic electroluminescence element having excellent power efficiency and a long lifetime.

It is a schematic sectional drawing which shows an example of a structure of the organic electroluminescent element which concerns on this invention. It is the schematic which shows an example of a structure of the vapor deposition source applicable by this invention. It is a schematic diagram which shows an example of the formation method of the light emitting layer using the some vapor deposition source of this invention. It is a graph for demonstrating the output intensity distribution of the light emitting layer forming gas discharged from a vapor deposition source, and a vapor deposition area. It is a graph which shows an example of the density | concentration profile in the film thickness direction of the blue light emission dopant in a light emitting layer. It is a schematic diagram which shows an example of arrangement | positioning with the vapor deposition source which concerns on this invention, and a board | substrate. It is a schematic diagram which shows arrangement | positioning with the some vapor deposition source and board | substrate which were used in the Example. It is a graph which shows an example of the density | concentration profile in the film thickness direction of the blue light emission dopant in the light emitting layer formed in the Example. It is a graph which shows another example of the concentration profile in the film thickness direction of the blue light emission dopant in the light emitting layer formed in the Example. It is a graph which shows another example of the concentration profile in the film thickness direction of the blue light emission dopant in the light emitting layer formed in the Example.

Hereinafter, embodiments for carrying out the present invention will be described in detail.

As a result of intensive studies in view of the above problems, the inventor forms a light emitting layer of an organic electroluminescence element by depositing the organic compound from a plurality of vapor deposition sources filled with the organic compound on a moving substrate. In the method for producing an organic electroluminescence device, 1) the plurality of vapor deposition sources are all filled with a host compound and a dopant compound, and 2) the mass ratio of the dopant compound to the host compound with respect to each other. 3) The region where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate is 10% or more of the total vapor deposition area. Found that an organic electroluminescence device manufacturing method with excellent and long driving life can be realized. It is up that led to.

Hereinafter, the details of the method for producing the organic electroluminescence element of the present invention will be described.

First, details of each component of the organic electroluminescence element according to the present invention (hereinafter also referred to as the organic EL element or the organic electroluminescence element according to the present invention) will be sequentially described.

<< Layer structure of organic EL element >>
Although the preferable specific example of the layer structure of the organic EL element which concerns on this invention below is shown below, this invention is not limited to these.

(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emission Layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode In the organic EL device according to the present invention, the light emitting layer unit has at least one light emitting layer having a configuration satisfying the requirements defined in the present invention. As long as it is configured, any number of layers may be stacked, but it is preferable that the light-emitting layer is preferably composed of only one light-emitting layer having requirements that satisfy the requirements of the present invention.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an organic electroluminescence element according to the present invention.

FIG. 1 a shows a schematic view of a lighting device using an organic EL element according to the present invention, and the organic EL element 101 of the present invention is covered with a glass cover 102. The sealing operation with the glass cover is performed in a glove box (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere.

In the organic EL element shown in FIG. 1 b), 105 denotes a cathode, 106 denotes an organic EL layer including a light emitting layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

The light emission color of the organic electroluminescent device according to the present invention is white, and the light emitting layer of the organic electroluminescent device preferably contains a host compound, a blue light emitting dopant, a green light emitting dopant and a red light emitting dopant. The maximum wavelength in the wavelength region of each light emitting dopant is preferably 465 to 480 nm for blue light emitting dopant, 500 to 515 nm for green light emitting dopant, and 600 to 620 nm for red light emitting dopant.

<Structure of light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer. The structure of the light emitting layer according to the present invention is not particularly limited as long as it satisfies the requirements defined in the present invention.

The formation of the light emitting layer is characterized by being performed by a vapor deposition method, but it is preferable to use a vacuum vapor deposition method that easily forms a concentration gradient of the light emitting dopant, and a line source type vapor deposition apparatus is more preferable for mass production.

As a method for forming a constituent layer other than the light emitting layer described later, for example, a vacuum deposition method, a spin coating method, a casting method, an LB method (Langmuir-Blodget method), an ink jet method, a spray method, a printing method, a slot The film can be formed by a known thin film forming method such as a mold coater method.

In the organic EL device according to the present invention, the light emitting layer may have two or more layers, but preferably comprises only one light emitting layer as described above.

<Method for forming light emitting layer>
Subsequently, the manufacturing method of the organic EL element of this invention and the formation method of a light emitting layer using the same are demonstrated in detail using figures.

In the method for producing an organic electroluminescent element of the present invention, an organic electroluminescent element is formed by evaporating the organic compound from a plurality of vapor deposition sources filled with the organic compound on a moving substrate to form a light emitting layer of the organic electroluminescent element. 1) The plurality of vapor deposition sources are all filled with a host compound and a dopant compound,
2) The plurality of vapor deposition sources have different mass ratios of the dopant compound to the host compound,
3) The area where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate is 10% or more of the total vapor deposition area,
Is a structural feature.

As described above, the first structural feature of the method for manufacturing an organic EL device of the present invention is that a plurality of vapor deposition sources are used in forming the light emitting layer, and each vapor deposition source is filled with a host compound and a dopant compound. It is the structure which is done.

FIG. 2 is a schematic view showing an example of a configuration example of an evaporation source used in the method for producing an organic electroluminescence element of the present invention.

As shown in FIG. 2, a vapor deposition source 1 that can be used for forming a light emitting layer applicable to the present invention mainly generates a vapor deposition head 2 for injecting a vapor deposition gas and a vapor deposition source gas. It is composed of units.

In the vapor deposition head 2, a plurality of nozzles 3 for injecting vapor deposition source gas is arranged in a row on the side facing the substrate. The nozzles 3 arranged in this line are installed so as to be perpendicular to the transport direction of the substrate P. The unit for generating the vapor deposition source gas is connected to the vapor deposition head 2 via a conduit 5.

As a dopant compound, a holder BD filled with a blue light emitting dopant, a holder GD filled with a green light emitting dopant, a holder RD filled with a red light emitting dopant, and a holder Host filled with a host compound are respectively connected via a control valve (needle valve) 10. Connected to the conduit 9. Each holder is provided with a raw material pallet 7 for holding a predetermined compound. In addition, a heating member H, for example, a ribbon heater or the like, is mounted on the outer periphery of each holder, and each holder is heated to a predetermined temperature to gasify the luminescent dopant or the host compound. The heating member H and the outer peripheral portions of the conduits 5 and 9 are also mounted.

Each light emitting dopant and host compound are introduced into the conduit 9 in a predetermined ratio by appropriately adjusting the heating temperature of each holder and the control valve (needle valve) 10, and then an inert gas from the end. While supplying G, the mixed gas containing each compound is introduced into the vapor deposition head 2. Examples of inert substances applicable to the present invention include nitrogen, carbon dioxide, and Group 18 elements of the periodic table, specifically neon, argon, krypton, xenon, radon, etc. In the invention, nitrogen and argon are particularly preferable.

In the method for producing an organic EL element of the present invention, as a second feature, a plurality of vapor deposition sources having the configuration described in FIG. 2 are arranged as shown in FIG. In addition, the plurality of vapor deposition sources are characterized in that the mass ratio of the dopant compound to the host compound is different from each other.

FIG. 3 is a schematic view showing an example of a method for arranging a plurality of vapor deposition sources and forming a light emitting layer on a substrate.

In FIG. 3, two

evaporation sources

2A and 2B having the structure shown in FIG. 2 are arranged at positions opposed to the substrate P moving from the right to the left in the drawing. A light-emitting layer having a concentration gradient is formed on the substrate by injecting a forming gas containing. The

evaporation sources

2A and 2B shown in FIG. 3 are shown as viewed from the direction A shown in FIG. 2, and the

nozzle portions

3A and 3B of the evaporation sources are arranged at right angles with respect to the transport direction of the substrate P. ing.

In the method for producing an organic EL element of the present invention, a specific method for forming a gradient structure of dopant concentration in the thickness direction of the light emitting layer will be described with reference to FIG.

As an example of forming a gradient structure of dopant concentration in the light emitting layer, a method of forming a configuration in which the blue light emitting dopant concentration is changed in the inclined structure in the film thickness direction of the light emitting layer and the green light emitting dopant and the red light emitting dopant concentration are constant. explain.

3, the first evaporation source 2A is arranged on the downstream side of the substrate P transported in the direction of the arrow, and the second evaporation source 2B is arranged on the upstream side thereof. At this time, on the substrate P surface, from the first evaporation source 2A, in the vapor deposition area 11 constituted by the vapor deposition area end 11A and the other vapor deposition area end 11B, the emission layer forming gas is 11C normal. It is injected in the direction to do. Similarly, from the second evaporation source 2B, in the vapor deposition area 12 constituted by the vapor deposition area end portion 12A and the other vapor deposition area end portion 12B, the light emitting layer forming gas is injected in a direction having 12C as a normal line. The

The vapor deposition area as used in the present invention is defined as follows.

FIG. 4 is a schematic diagram for explaining a vapor deposition area formed by a vapor deposition source.

As shown in FIG. 4, the light emitting layer forming gas containing each color dopant and host compound is discharged from the nozzle 3 A of the vapor deposition source 2 A using the vapor deposition source having the configuration shown in FIG. 2. As shown in FIG. 4, the ionic strength decreases as the central portion 11C becomes the maximum value and becomes the peripheral portion.

In the profile having such an ion intensity distribution, the vapor deposition area referred to in the present invention is up to a region range (PWmin) having an output intensity of PWmax × 0.05, where PWmax is the output intensity at the central portion showing the maximum value. Is defined as a deposition area. That is, when the maximum output intensity PWmax is set to 100%, it is set as an area up to 5% of the maximum output intensity PWmax at both ends.

In the present invention, the dopant compound held by the vapor deposition source is a blue light emitting dopant, a green light emitting dopant, and a red light emitting dopant, and the concentration of the blue light emitting dopant in the plurality of vapor deposition sources is different, and the blue light emitting dopant is present in the light emitting layer. It is preferable to have a gradient concentration in the thickness direction.

That is, the blue light emission dopant concentration in the first vapor deposition source 2A is set to be higher than the blue light emission dopant concentration in the second vapor deposition source 2B. That is, as defined in the above item 2), the mass ratio of the dopant compound to the host compound is different from each other in the plurality of vapor deposition sources.

In the present invention, the dopant compound held by the vapor deposition source is a blue light emission dopant, a green light emission dopant, and a red light emission dopant, and the concentrations of the green light emission dopant and the red light emission dopant in the plurality of vapor deposition sources are equal, It is preferable that the concentration of the green light-emitting dopant and the red light-emitting dopant is uniform in the thickness direction. That is, by setting the green light emission dopant and the red light emission dopant concentration to the same concentration between the two

vapor deposition sources

2A and 2B, the concentration can be made constant in the entire film thickness region of the light emitting layer to be formed.

Further, as shown in FIG. 3, a configuration in which the vapor deposition area 11 formed by the first vapor deposition source 2 A and a part of the vapor deposition area 12 formed by the second vapor deposition source overlap on the substrate P, that is, As defined in the above item 3), the area where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate is 10% or more of the total vapor deposition area. Specifically, on the substrate P, the area I formed by the light emitting layer forming gas alone containing the higher concentration blue light emitting dopant, which is emitted from the first vapor deposition source 2A, and the first vapor deposition source 2A. It is formed by mixing a light emitting layer forming gas containing a high concentration blue light emitting dopant that is emitted more from a light emitting layer forming gas containing a low concentration blue light emitting dopant that is emitted from the second vapor deposition source 2B. The area II which is the low concentration region is formed by the area II which is the intermediate concentration region and the light emitting layer forming gas containing the low concentration blue light emitting dopant emitted from the second vapor deposition source 2B. The area where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate as defined in the present invention is 10% or more of the total vapor deposition area. The ratio of the area II to the total vapor deposition area (area I + area II + area III) The ratio of the area II is further preferably 20% or more, and particularly preferably 35% or more including 100% as the upper limit.

In the present invention, the discharge surfaces of the plurality of vapor deposition sources and the substrate surface may be parallel as shown in FIG. 7 a, but a more preferable configuration is as shown in FIGS. 3 and 6. In addition, the surface 14 with respect to the discharge normals 11C and 12C of the respective

vapor deposition sources

2A and 2B is arranged so as to be non-parallel to the surface of the substrate P. From the viewpoint of being formed.

Therefore, in the present invention, as shown in FIG. 3, the intersection point 11D between the discharge normal line 11C of the vapor deposition source 2A and the substrate P and the intersection point 12D between the discharge normal line 12C of the vapor deposition source 2B and the substrate P are different. Position.

By forming the light-emitting layer on the substrate P with the above-described configuration, a light-emitting layer having a gradient concentration as the blue light-emitting dopant concentration can be formed in the area II that is an intermediate concentration region.

FIG. 5 is a graph showing an example of a profile of the blue light emitting dopant concentration in the light emitting layer, where the vertical axis indicates the blue light emitting dopant concentration (ionic strength), and the horizontal axis indicates the film thickness of the light emitting layer. The value side is the anode side, and the maximum value side of the film thickness is the cathode side. As shown in FIG. 5, as the vapor deposition area, a blue light emitting dopant concentration area I, an intermediate concentration area II, and a low concentration area area III are obtained. After that, the area II where the concentration gradually decreases gradually is formed in the range of 10% or more of the total evaporation area using the evaporation source 2A and the evaporation source 2B, and finally the blue color near the cathode Area III having a low luminescent dopant concentration is formed by the vapor deposition source 2B alone.

In the present invention, the concentration distribution of the light-emitting dopant contained in the light-emitting layer of the organic EL element can be detected in the film thickness direction by TOF-SIMS (time-of-flight secondary ion mass spectrometry). In the present invention, a constituent element of a light emitting dopant, for example, Ir or the like is selected as a target element, elemental analysis in the depth direction of the light emitting layer is performed, and the concentration gradient of the light emitting dopant in the light emitting layer is measured from the result. can do.

Hereinafter, an example of measurement when Ir is used as a target element as a constituent element of the luminescent dopant will be described.

<Concentration gradient analysis of target element (Ir) in light emitting layer>
For analysis of the concentration gradient of the target element in the light emitting layer, Ir (iridium) is selected as the target element, and elemental analysis in the depth direction in the light emitting layer is performed. When it is desired to measure the compound itself, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) method is preferred. In this case, the distribution of the dopant compound in the depth direction can be known by measuring the distribution of fragment ions obtained from the compound in the oblique cross-section portion that has been cut off obliquely and the shaved cross-section. Examples of the oblique cutting method include a method using an ultramicrotome used for preparing a sample for an electron microscope, and a method using a precision oblique cutting device such as a die-plautes Cycus NN type. For the ToF-SIMS method, for example, the Japanese Society of Surface Science “Secondary Ion Mass Spectrometry (Surface Science and Technology Selection)” (Maruzen) can be referred to. In the ToF-SIMS method, sputtering is performed by irradiating a sample surface with an ion beam called primary ions under a high vacuum of about 10 ⁻⁸ Pa. It is a method of analyzing compounds present on the surface by mass spectrometry of secondary ions emitted by very gentle sputtering by making the primary ion beam very low current and pulsed. . By measuring while scanning the primary ions, the distribution of secondary ions emitted by sputtering can be measured.

The effectiveness of the concentration distribution profile in the light emitting layer of the blue light emitting dopant in the present invention will be described in more detail. In the present invention, in the case of a material having a high hole transporting property of the blue light emitting dopant, it is contained at a high concentration at the anode side end of the light emitting layer, and has a concentration distribution so that the concentration decreases toward the cathode side. It is preferable that it is the structure which has. The average content of the blue light emitting dopant in the portion from the anode side interface of the light emitting layer to the center portion of the light emitting layer may be larger than the average content from the cathode side interface to the center portion of the light emitting layer, but preferably the end portion on the anode side is the most. It is preferable that the concentration is high and decreases monotonically from the anode side end to the cathode side end. Monotonically decreasing means that there is no maximum concentration portion except for the anode side end of the light emitting layer. In the present invention, the anode side end portion refers to a region having a smaller thickness of 5 nm from the anode side interface of the light emitting layer or 1/20 of the thickness of the entire light emitting layer, Denotes a region having a smaller thickness of 5 nm from the cathode side interface of the light emitting layer or 1/20 of the entire light emitting layer.

If the blue light-emitting dopant has a high electron transport property, the same effect can be obtained if it is contained at a high concentration on the cathode side of the light-emitting layer and has a concentration distribution so that the concentration decreases toward the anode side. It is done.

The light emitting layer having the structure of the present invention provides an organic electroluminescence device having excellent power efficiency, long life, and excellent chromaticity stability and uniformity.

On the other hand, in the entire light emitting layer (area I to area III) shown in FIG. 5, it is preferable that the concentrations of the green light emitting dopant and the red light emitting dopant are constant.

Hereinafter, the concentration distribution of the green light emitting dopant and the red light emitting dopant in the light emitting layer in the present invention will be described in detail.

In the present invention, when blue, green, and red phosphorescent dopants are contained in the same light emitting layer, the lowest excited triplet energy level is changed from the blue emitting dopant having the highest lowest excited triplet energy level (T1). Since the green light-emitting dopant and the red light-emitting dopant with low energy have exciton energy transfer, when the blue, green, and red concentrations are the same, blue hardly emits light and white light emission cannot be obtained. Therefore, when the light emitting layer is formed by vapor deposition, for example, the co-evaporation is performed by setting the concentrations of the light emitting dopants of blue, green, and red to 15% by volume, 0.13% by volume, and 0.13% by volume, respectively. Luminescence is obtained. In this case, the blue light-emitting dopant is not affected by the concentration fluctuation, but the low-concentration green light-emitting dopant and the red light-emitting dopant need to have a low deposition rate, and the deposition rate is unstable due to the low rate. Color unevenness is likely to occur due to slight fluctuations in the deposition rate. Therefore, in the light emitting layer of the organic EL device according to the present invention, it is important that the green light emitting dopant and the red light emitting dopant are uniformly distributed in the light emitting layer as low concentration dopants.

<Components of organic EL elements>
Next, details of each component of the organic EL element according to the present invention will be described.

[Components of light-emitting layer]
(Luminescent dopant)
First, the light emitting dopant according to the present invention will be described.

Examples of the light emitting dopant according to the present invention include a phosphorescent light emitting dopant (hereinafter also referred to as a phosphorescent light emitter, a phosphorescent compound, and a phosphorescent light emitting compound) and a fluorescent light emitting dopant. In order to improve efficiency, it is more preferable to use a phosphorescent emitter.

<Phosphorescent dopant>
The phosphorescent dopant applicable to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield. The phosphorescence quantum yield is preferably 0.1 or more, although it is defined as a compound of 0.01 or more at 25 ° C.

The phosphorescent quantum yield can be measured, for example, by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7.

There are two types of light emission principles of phosphorescent dopants. One type is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is phosphorescent. The energy transfer type that obtains light emission from the phosphorescent dopant by transferring to the phosphorescent dopant, and the other type is that the phosphorescent dopant becomes a carrier trap, and carrier recombination occurs on the phosphorescent dopant, Although it is a carrier trap type in which light emission from a phosphorescent dopant can be obtained, in any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound. .

The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL device.

The phosphorescent dopant according to the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex system). Compound) and rare earth complexes, and most preferred is an iridium compound.

Specifically, it is a compound described in the following patent publications, for example, International Publication No. 00/70655 pamphlet, JP 2002-280178 A, 2001-181616, 2002-280179, 2001-181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002-324679, WO 02/15645, JP-A 2002-332291, 2002-50484, 2002-332292, 2002-83684, 2002-540572 Publication, JP 002-117978, 2002-338588, 2002-170684, 2002-352960, WO01 / 93642, JP2002-50483, 2002-1000047 No. 2002-173684, No. 2002-359082, No. 2002-175484, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808 JP2003-7471, JP2002-525833A, JP2003-31366A, 2002-226495, 2002-234894, 2002-233506, 2002-2417. No. 1, No. 2001-319779, No. 2001-319780, No. 2002-62824, No. 2002-1000047, No. 2002-203679, No. 2002-343572, No. 2002-203678. Can be used.

In addition, these exemplified compounds are, for example, Inorg. Chem. , 40, 1704 to 1711.

(Host compound)
Next, the host compound contained in the light emitting layer will be described.

The host compound contained in the light emitting layer of the organic EL device according to the present invention is preferably a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1, more preferably phosphorescence quantum. The compound yield is less than 0.01. Moreover, in the compound contained in a light emitting layer, it is preferable that the mass ratio in the layer is 20 mass% or more.

As the host compound according to the present invention, the host compound may be used alone or in combination of two or more.

The light-emitting host compound used in the present invention is not particularly limited in terms of structure, but typically, a carbazole derivative, a triarylamine derivative, an aromatic borane derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, Those having a basic skeleton such as an oligoarylene compound, or a carboline derivative or a diazacarbazole derivative (herein, a diazacarbazole derivative means that at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is nitrogen Represents an atom substituted with an atom).

The host compound used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). .

As the host compound, a compound having a hole transporting ability and an electron transporting ability, which prevents emission of light from being increased in wavelength and has a high Tg (glass transition temperature) is preferable.

As specific examples of conventionally known host compounds, compounds described in the following documents are suitable. For example, Japanese Patent Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. No. 2002-302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, and the like.

In the present invention, in the case of having a plurality of light emitting layers, the host compound may be different for each light emitting layer, but it is preferable that they are the same compound because excellent driving life characteristics can be obtained.

Further, it is preferable that the host compound has a minimum excitation triplet energy (T1) larger than 2.7 eV because higher luminous efficiency can be obtained. The lowest excited triplet energy as used in the present invention refers to the peak energy of an emission band corresponding to the transition between the lowest vibrational bands of a phosphorescence emission spectrum observed at a liquid nitrogen temperature after dissolving a host compound in a solvent.

In the present invention, a compound having a glass transition point of 90 ° C. or higher is preferable, and a compound having a glass transition temperature of 130 ° C. or higher is preferable because excellent driving life characteristics can be obtained.

Here, the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

In the organic EL device according to the present invention, since the host material is responsible for carrier transportation, a material having carrier transportation ability is preferable. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance of hole and electron injection / transport, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material.

Next, other constituent layers other than the light emitting layer of the organic EL device according to the present invention will be described.

[Injection layer: electron injection layer, hole injection layer]
The injection layer can be provided as necessary, and may exist between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer.

An injection layer is a layer provided between an electrode and an organic layer in order to lower drive voltage and improve light emission luminance. For example, “Organic EL element and its forefront of industrialization (November 30, 1998, NTS Corporation) Issue) ”, Chapter 2,“ Electrode Materials ”(pages 123 to 166), which is described in detail, and has a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer). .

Details of the structure of the anode buffer layer (hole injection layer) are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc. Examples include a phthalocyanine buffer layer typified by copper phthalocyanine, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. . Further, a layer using a material described in JP-T-2003-519432 is also preferable.

Details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. .

The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material used.

[Blocking layer: hole blocking layer, electron blocking layer]
The blocking layer is provided as necessary in addition to the light emitting layer, which is the basic constituent layer of the organic EL device according to the present invention. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)” on page 237. There is a hole blocking (hole blocking) layer.

The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer as needed.

The hole blocking layer provided in the organic EL device according to the present invention is preferably provided adjacent to the light emitting layer.

On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.

The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

(Hole transport layer)
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has either hole injection or transport or electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

As the hole transport material, the above-mentioned compounds can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, as well as those described in US Pat. No. 5,061,569 Having four condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type ( MTDATA) and the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), JP-A-11-251067, J. MoI. Huang et. al. It is also possible to use a hole transport material that has so-called p-type semiconducting properties, as described in the literature (Applied Physics Letters 80 (2002), p. 139), JP 2003-519432 A. it can. In the present invention, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

For the hole transport layer, the hole transport material may be selected from, for example, a vacuum deposition method, a spin coating method, a casting method, an LB method (Langmuir Blodget method), an ink jet method, a spray method, a printing method, a slot type coater method, etc. The film can be formed by a known thin film forming method. The film thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 nm to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

(Electron transport layer)
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

Conventionally, when a single electron transport layer and a plurality of electron transport layers are used, as an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side Any material may be used as long as it has a function of transmitting electrons injected from the cathode to the light-emitting layer, and any material known in the art can be selected and used. For example, nitro-substituted fluorene Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Further, the distyrylpyrazine derivatives exemplified as the material of the light emitting layer can also be used as an electron transport material, and like the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC can be used. A semiconductor can also be used as an electron transport material.

For the electron transport layer, the above-mentioned electron transport material is a known material such as a vacuum deposition method, a spin coating method, a casting method, an LB method (Langmuir-Blodget method), an ink jet method, a spray method, a printing method, or a slot type coater method. The film can be formed by a thin film forming method. The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use an electron transport material that has n-type semiconductor properties doped with impurities. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use an electron transport material that has such n-type semiconductor properties because an element with lower power consumption can be produced.

〔substrate〕
The substrate applied to the organic EL device according to the present invention (hereinafter also referred to as a substrate, a support substrate, a substrate, a support, etc.) is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the substrate side, the substrate is preferably transparent. Examples of the transparent substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable substrate is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones, Cycloolefin resins such as polyether imide, polyether ketone imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned. An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability measured by a method according to JIS K 7129-1992 is 0.01 g / m ^2. It is preferably a barrier film of day · atm or less, and further, the oxygen permeability measured by a method according to JIS K 7126-1992 is 10 ⁻³ g / m ² / day or less, water vapor permeability Is preferably a high barrier film of 10 ⁻³ g / m ² / day or less, and the water vapor permeability and oxygen permeability are both 10 ⁻⁵ g / m ² / day or less. Further preferred.

The material for forming the barrier film may be any material as long as it has a function of suppressing intrusion of elements that cause deterioration of the element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Furthermore, in order to improve the fragility of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is also preferable.

Examples of the opaque substrate include a metal plate / film such as aluminum and stainless steel, an opaque resin substrate, a ceramic substrate, and the like.

[Sealing]
Examples of the sealing means used for sealing the organic EL element according to the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive.

The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Moreover, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Furthermore, the polymer film preferably has an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻³ g / m ² / day or less. Further, it is more preferable that both the water vapor permeability and the oxygen permeability are 10 ⁻⁵ g / m ² / day or less.

For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used. Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, the heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

In addition, since an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print it like screen printing.

In addition, it is also preferable to coat the electrode and the organic layer on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and form an inorganic or organic layer in contact with the support substrate to form a sealing film. it can. In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of the element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. it can. Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil is injected in the gas phase and the liquid phase. Is preferred. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.

Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (eg, barium perchlorate) , Magnesium perchlorate, etc.), and sulfates, metal halides and perchloric acids are preferably anhydrous salts.

[Protective film, protective plate]
In order to increase the mechanical strength of the organic EL element, a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the substrate with the organic layer interposed therebetween. In particular, when sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. as those used for the sealing can be used, but the polymer plate is light and thin. -It is preferable to use a film.

〔anode〕
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode substance include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. When light emission is taken out from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

〔cathode〕
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.

In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a film thickness of 1 nm to 20 nm. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, anode / hole injection layer / hole transport layer / light emitting layer (formed in accordance with the method for producing the organic EL device of the present invention) / hole blocking layer / electron transport A method for producing an organic EL element having a layer / cathode will be described.

First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate so as to have a thickness of 1 μm or less, preferably 10 nm to 200 nm, by a method such as vapor deposition or sputtering to produce an anode. . Next, a hole injection layer which is an organic EL element material, a hole transport layer, and then a light emitting layer are formed according to the method for producing an organic EL element of the present invention, and further a hole blocking layer and an electron transport layer. An organic compound thin film is formed.

As a method of thinning the organic compound thin film excluding the light emitting layer, as described above, vapor deposition method, wet process (spin coating method, casting method, ink jet method, printing method, LB method (Langmuir Blodget method), spray method Printing method, slot type coater method, etc., but it is easy to obtain a homogeneous film and it is difficult to generate pinholes, vacuum deposition method, spin coating method, ink jet method, printing method, slot type. The coater method is particularly preferred. Further, different film forming methods may be applied for each layer. When the vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally the boat heating temperature is 50 ° C. to 450 ° C., the degree of vacuum is 10 ⁻⁶ Pa to 10 ⁻² Pa, and the vapor deposition rate is 0. It is desirable to select appropriately within the range of 01 nm / second to 50 nm / second, substrate temperature −50 ° C. to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 nm to 200 nm. After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

It is also possible to reverse the production order to produce a cathode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 V to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

An organic electroluminescence device emits light inside a layer having a refractive index higher than that of air (refractive index of about 1.6 to 2.1), and can extract only about 15% to 20% of light generated in the light emitting layer. It is generally said that there is no. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.

As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-134795), a method for forming a reflective surface on the side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Laid-Open No. 62-172691), lower refractive than the substrate between the substrate and the light emitter A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer, and the light emitting layer (including between the substrate and the outside) ( JP 1 No. -283751 Publication), and the like.

In the present invention, these methods can be used in combination with the organic electroluminescence device of the present invention, but a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, A method of forming a diffraction grating between any layers of the transparent electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

When a low refractive index medium is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. .

Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is preferable that it is 1.35 or less.

Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

The method of introducing a diffraction grating into an interface that causes total reflection or in any medium is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction, such as first-order diffraction or second-order diffraction. The light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode). , Trying to extract light out.

It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.

However, by making the refractive index distribution a two-dimensional distribution, the light traveling in all directions is diffracted, and the light extraction efficiency is increased.

The position where the diffraction grating is introduced may be in any layer or in the medium (in the transparent substrate or transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium. The arrangement of the diffraction gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

The organic electroluminescence device of the present invention is processed in a specific direction by, for example, providing a structure on a microlens array on the light extraction side of a support substrate (substrate) or combining it with a so-called condensing sheet. For example, the brightness | luminance in a specific direction can be raised by condensing in a front direction with respect to an element light emission surface.

As an example of a microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

As the condensing sheet, it is possible to use, for example, an LED backlight of a liquid crystal display device that has been put into practical use. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, a substrate may be formed with a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or the apex angle is rounded and the pitch is changed randomly. Other shapes may also be used.

Further, in order to control the light emission angle from the organic EL element, a light diffusion plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

《Lighting device》
An illumination device to which the organic EL element according to the present invention is applied will be described.

The organic EL device according to the present invention may be used as a kind of lamp such as an illumination or exposure light source, a projection device that projects an image, or a display that directly recognizes a still image or a moving image. It may be used as a device (display). The driving method when used as a display device for moving image reproduction may be either a simple matrix (passive matrix) method or an active matrix method.

In the white organic electroluminescence element used in the present invention, patterning may be performed by a metal mask, an inkjet printing method, or the like at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned. The light emitting dopant used in the light emitting layer is not particularly limited. For example, in the case of a backlight in a liquid crystal display element, the platinum complex according to the present invention is adapted so as to conform to the wavelength range corresponding to the CF (color filter) characteristics. Any one of known light-emitting dopants may be selected and combined, or combined with the light extraction and / or light collecting sheet according to the present invention to be whitened.

Thus, the white organic EL element of the present invention is described in claim 7 by combining the CF (color filter) and arranging the element and the driving transistor circuit in accordance with the CF (color filter) pattern. In this way, white light extracted from the organic electroluminescence device is used as a backlight, and blue light, green light, and red light are obtained through a blue filter, a green filter, and a red filter. An organic electroluminescence display is preferable and preferable.

<< Industrial field to which the organic EL element according to the present invention is applied >>
The organic EL element according to the present invention can be used as a display device, a display, and various light sources. Examples of light sources include home lighting, interior lighting, backlights for watches and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Although it is not limited to this, it can be effectively used for backlights of various display devices combined with color filters, light diffusion plates, light extraction films, etc., and as a light source for illumination.

Utilizing the characteristics of the organic EL device according to the present invention, product display / display lighting, built-in lighting for interior / furniture / building materials, automotive lighting, light-emitting display, public transportation (train, subway, bus, aircraft) , Ships, etc.) in-car lighting and display bodies, light sources for OA equipment, industrial inspection systems (for example, illumination light sources used for image sensors, backlights, etc.), light sources for agricultural products, evacuation lighting, and photography In addition to lighting, home appliances (light sources for sewing machines, microwave ovens, dishwashers / dryers, refrigerators, AV equipment, etc.), amusement facilities, illumination lighting, lighting for belongings and clothes, communication light source, medical light source, As a pest control apparatus as disclosed in JP 2001-269105 A, as a mirror illumination as disclosed in JP 2001-286373 A, As a bathroom lighting system as disclosed in Japanese Unexamined Patent Publication No. 2003-288895, as an artificial light source for plant growth as disclosed in Japanese Patent Application Laid-Open No. 2004-321074, a water pollution measuring device as disclosed in Japanese Patent Application Laid-Open No. 2004-354232 is disclosed. As a light-emitting body, a therapeutic adherend using a photosensitive drug as disclosed in JP-A-2004-358063, useful as a medical surgical light as disclosed in JP-A-2005-322602. is there.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Organic EL element >>
[Production of Organic EL Element 1]
(Formation of anode)
Transparent support with this ITO transparent electrode attached after depositing ITO (Indium Tin Oxide) with a thickness of 110 nm on a 30 mm × 30 mm, 0.7 mm thick glass substrate as an anode. The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then the transparent support substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

(Formation of hole injection layer)
Next, after reducing the vacuum to 1 × 10 ⁻⁴ Pa, the molybdenum deposition crucible containing m-MTDATA was energized and heated, and deposited on a transparent support substrate at a deposition rate of 0.1 nm / second to 20 nm. The hole injection layer was provided.

(Formation of hole transport layer)
Next, with a vacuum degree of 1 × 10 ⁻⁴ Pa, the molybdenum vapor deposition crucible containing α-NPD was energized and heated, and vapor deposition was performed at a vapor deposition rate of 0.1 nm / second to provide a 30 nm hole transport layer. It was.

(Light emitting layer forming method 1)
Only one vapor deposition source having the configuration shown in FIG. 2 is used, and the arrangement of the substrate provided with the hole transport layer and the vapor deposition source is as shown in FIG. 7 d). As shown, the light emitting layer 1 in which the blue light emitting dopant was formed at a uniform concentration of 35% by mass was formed over the entire light emitting layer. This method is referred to as a light emitting layer forming method 1.

Specifically, FIrpic (compound B) is loaded as a blue light emitting dopant on the material palette 7 of the holder BD holding the blue light emitting dopant shown in FIG. 2, and the green light emitting dopant is loaded on the material palette 7 of the holder GD holding the green light emitting dopant. Ir (ppy) ₃ (compound G) as a raw material palette 7 of the holder RD holding the red light emitting dopant, Ir (piq) ₃ (compound R) as a red light emitting dopant, and a raw material palette of the holder Host holding the host compound 7 was charged with CBP (Compound H) as a host compound.

Next, after each compound in the raw material pallet 7 is vaporized by the heating member H attached to each holder, the argon gas is supplied as an inert gas G from the end of the conduit 9, and the heating temperature by the heater 8 and each holder The control valve (needle valve) 10 is appropriately adjusted, the blue light emitting dopant (Compound B) is 35% by mass, the green light emitting dopant (Compound B) is 0.2% by mass, and the red light emitting dopant (Compound R) is 0.2%. A gas for forming a light emitting layer containing 6% by mass of the host compound (Compound H) is prepared, a gas for forming the light emitting layer containing each compound is introduced into the vapor deposition head 2, and holes are transported from the nozzle 3. The blue light emitting dopant concentration profile (uniform content of 35% by mass) shown in FIG. To form a light-emitting layer 1 having a thickness of 70nm with.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 1 are 0.2 mass% uniform concentration distribution in the whole region.

(Formation of electron transport layer)
On the light emitting layer 1, compound M-1 was vapor-deposited so that it might become a film thickness of 30 nm, the electron carrying layer was formed, and also KF was formed in thickness 2nm.

(Formation of cathode)
An aluminum thin film was deposited to 110 nm on the electron transport layer to form a cathode.

(Production of organic EL element)
Subsequently, the non-light-emitting surface of the element was covered with a glass case, and an organic EL element 1 having the configuration shown in FIG. 1 was produced.

[Production of Organic EL Element 2]
In the production of the organic EL element 1, the organic EL element 2 was produced in the same manner except that the light emitting layer forming method 1 was replaced with the following light emitting layer forming method 2.

(Light emitting layer forming method 2)
In the light emitting layer forming method 1, the heating temperature by the heater 8 and the control valve (needle valve) 10 of each holder are adjusted as appropriate, and the concentration of the blue light emitting dopant (compound B) in the light emitting layer forming gas is 5% by mass. In the same manner except that the content concentration of the host compound (Compound H) is changed to 94.6% by mass, the arrangement of the substrate provided with the hole transport layer and the vapor deposition source is as shown in FIG. A light emitting layer 2 having a thickness of 70 nm having a blue light emitting dopant concentration profile (uniform content of 5% by mass) shown in FIG. This method is referred to as a light emitting layer forming method 2.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 2 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 3]
In the production of the organic EL element 1, an organic EL element 3 was produced in the same manner except that the light emitting layer forming method 1 was replaced with the light emitting layer forming method 3 described below.

(Light emitting layer forming method 3)
In the formation of the light emitting layer 1, the heating temperature by the heater 8 and the control valve (needle valve) 10 of each holder are appropriately adjusted, and the concentration of the blue light emitting dopant (compound B) in the light emitting layer forming gas is 20% by mass, Except for changing the content concentration of the host compound (Compound H) to 79.6% by mass, the arrangement of the substrate provided with the hole transport layer and the vapor deposition source is configured as shown in FIG. A light-emitting layer 3 having a thickness of 70 nm having a blue light-emitting dopant concentration profile (uniform content of 20% by mass) shown in 8) a) -3 was formed. This method is referred to as a light emitting layer forming method 3.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 3 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 4]
In the production of the organic EL element 1, an organic EL element 4 was produced in the same manner except that the light emitting layer forming method 1 was replaced with the light emitting layer forming method 4 described below.

(Light emitting layer forming method 4)
Two vapor deposition sources having the configuration shown in FIG. 2 are used, the arrangement of the substrate and the vapor deposition source is as shown in FIG. 7 b), and the vapor deposition source surface is inclined by 15 degrees with respect to the substrate surface. As shown in FIG. 8 b), the blue light emitting dopant concentration at the time of forming the light emitting layer is 25 mass%, and is 15 mass% at the time of completing the light emitting layer formation (light emitting layer outermost surface portion). The light emitting layer 4 having the gradient concentration of the blue light emitting dopant changing from 25% by mass to 15% by mass was formed. This method is referred to as a light emitting layer forming method 4. The entire area of the light emitting layer 4 formed by the forming method 4 is the area II shown in FIG. 5, and the area I and the area III do not exist.

The detailed conditions of the first evaporation source 2A and the second evaporation source 2B are shown below.

<First evaporation source>
2 is loaded with FIrpic (compound B) as a blue light emitting dopant in the holder BD raw material palette 7 holding the blue light emitting dopant shown in FIG. ppy) ₃ (compound G) is hosted in the raw material palette 7 of the holder RD holding the red light emitting dopant, Ir (piq) ₃ (compound R) as a red light emitting dopant, and hosted in the raw material palette 7 of the holder Host holding the host compound CBP (Compound H) was charged as a compound, respectively.

Next, after each compound in the raw material pallet 7 is vaporized by the heating member H attached to each holder, the argon gas is supplied as an inert gas G from the end of the conduit 9, and the heating temperature by the heater 8 and each holder The control valve (needle valve) 10 is appropriately adjusted, 25% by mass of the blue luminescent dopant (Compound B), 0.2% by mass of the green luminescent dopant (Compound B), and 0.2% of the red luminescent dopant (Compound R). A light emitting layer forming gas 4A containing 74.6% by weight of a host compound (Compound H) is prepared, and the light emitting layer forming gas 4A containing each compound is introduced into the vapor deposition head 2, and is positively supplied from the nozzle 3. While transporting the substrate provided with the hole transport layer, it was emitted at a deposition rate of 0.0002 nm / second.

<Second evaporation source>
In the first vapor deposition source, instead of the light emitting layer forming gas 4A, 15% by weight of the blue light emitting dopant (Compound B), 0.2% by weight of the green light emitting dopant (Compound B), and the red light emitting dopant (Compound R) ) Was changed to 0.2% by mass and the host compound (Compound H) was changed to 84.6% by mass, and the light emitting layer forming gas 4B was used.

<Formation of light emitting layer>
As shown in FIG. 7b), the area 11 formed by the first evaporation source 2A and the vapor deposition area 12 formed by the second vapor deposition source 2B overlap in the whole area, The light emitting layer 4 having a thickness of 70 nm having the blue light emitting dopant concentration profile shown in FIG.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 4 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 5]
In the production of the organic EL element 4, the organic EL element 5 was produced in the same manner except that the light emitting layer forming method 4 was replaced with the following light emitting layer forming method 5.

(Light emitting layer forming method 5)
<First evaporation source>
35% by mass of the blue luminescent dopant (Compound B), 0.2% by mass of the green luminescent dopant (Compound B), 0.2% by mass of the red luminescent dopant (Compound R), and 64.6 of the host compound (Compound H). A gas 5A for forming a light emitting layer containing 5% by mass was prepared and used.

<Second evaporation source>
5% by mass of the blue luminescent dopant (Compound B), 0.2% by mass of the green luminescent dopant (Compound B), 0.2% by mass of the red luminescent dopant (Compound R), and 94.6 of the host compound (Compound H). A gas 5A for forming a light emitting layer containing 5% by mass was prepared and used.

<Formation of light emitting layer>
Two vapor deposition sources having the configuration shown in FIG. 2 are used, and the arrangement of the substrate and the vapor deposition source shown in FIG. 7 b is an arrangement in which the vapor deposition source surface is inclined by 15 degrees with respect to the substrate surface. As shown in c), the blue light-emitting dopant concentration at the time of forming the light-emitting layer is 35% by weight, and 35% by weight over the entire light-emitting layer so that the light-emitting layer formation is 5% by weight when the light-emitting layer is formed (outermost surface portion) The light emitting layer 5 having a gradient concentration of the blue light emitting dopant that changes from 5 to 5% by mass was formed. This method is referred to as a light emitting layer forming method 5. The entire area of the light emitting layer 5 formed by the forming method 5 is the area II shown in FIG. 5, and the area I and the area III do not exist.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 5 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 6]
In the production of the organic EL element 4, the organic EL element 6 was produced in the same manner except that the light emitting layer forming method 4 was replaced with the following light emitting layer forming method 6.

(Light emitting layer forming method 6)
The compositions of the light emitting layer forming gas (blue light emitting dopant: 25% by mass) used in the first evaporation source 2A and the light emitting layer forming gas (blue light emitting dopant: 15% by mass) used in the second evaporation source 2B emit light. The method was the same as in Layer formation method 4.

<Formation of light emitting layer>
The first vapor deposition source is formed by using two vapor deposition sources having the configuration shown in FIG. 2 and arranging the substrate and the vapor deposition source as shown in FIG. An area I formed only by 2A, an area II where the first vapor deposition source 2A and the second vapor deposition source 2B overlap, and an area III formed only by the second vapor deposition source 2B are formed. As shown in FIG. 8d), from the start of formation of the light emitting layer to 10% of the total film thickness, the area I where the blue light emitting dopant is a uniform concentration region of 25% by mass, 10% of the total film thickness. As described above, up to 90% is the area II where the concentration of the blue light-emitting dopant is inclined from 25% to 15%, and from 90% to 100% is the area III where the blue light-emitting dopant is a uniform concentration region of 15% by mass. The light emitting layer 6 was formed. This method is referred to as a light emitting layer forming method 6. In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 6 are uniform concentration distribution of 0.2 mass% in the whole region.

[Production of organic EL elements 7 to 11]
In the production of the organic EL element 6, the ratio of the area II to the blue light emitting dopant and the host compound concentration in the first evaporation source 2 A and the blue light emitting dopant and the host compound concentration in the second evaporation source 2 B when forming the light emitting layer. The organic EL elements 7 to 11 were produced in the same manner as the light emitting layer forming methods 7 to 11 except that the conditions described in Table 1 were changed.

The blue light emitting dopant concentration profile in the light emitting layer forming methods 7 to 11 is as follows.

Light emitting layer formation method 7: Blue light emitting dopant concentration profile shown in FIG. 9 a) Light emitting layer forming method 8: Blue light emitting dopant concentration profile shown in FIG. 9 b) Light emitting layer forming method 9: FIG. 9 c) The blue light emitting dopant concentration profile shown in FIG. 10: The light emitting layer forming method 10: The blue light emitting dopant concentration profile shown in FIG. 9d) The light emitting layer forming method 11: The blue light emitting dopant concentration profile shown in FIG. The green light-emitting dopant (compound B) and the red light-emitting dopant in ˜11 have a uniform concentration distribution of 0.2 mass% over the entire area.

[Production of Organic EL Element 12]
In the production of the organic EL element 6, an organic EL element 12 was produced in the same manner except that the following light emitting layer forming method 12 was used instead of the light emitting layer forming method 6.

(Method 12 for forming light emitting layer)
In contrast to the light emitting layer forming method 6, as shown in FIG. 7 c, the substrate and each evaporation source surface are arranged in parallel, and the evaporation area 11 formed by the first evaporation source 2 A, and the second evaporation The vapor deposition area 12 formed by the source 2B did not overlap at all, and this was used as the light emitting layer forming method 12. The blue light emission dopant concentration profile of the formed light emitting layer is shown in FIG. The light emitting layer formed by the light emitting layer forming method 12 is composed of only area I and area III.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 12 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 13]
In the production of the organic EL element 7, an organic EL element 13 was produced in the same manner except that the following light emitting layer forming method 13 was used instead of the light emitting layer forming method 7.

(Method 13 for forming light emitting layer)
With respect to the light emitting layer forming method 7, as shown in FIG. 7c, the substrate and each evaporation source surface are arranged in parallel, and the evaporation area 11 formed by the first evaporation source 2A, and the second evaporation The vapor deposition area 12 formed by the source 2B did not overlap at all, and this was used as the light emitting layer forming method 12. The blue light emission dopant concentration profile of the formed light emitting layer is shown in FIG. The light emitting layer formed by the light emitting layer forming method 13 is composed of only area I and area III.

In addition, the green light emission dopant (compound B) and the red light emission dopant in the light emitting layer 13 are 0.2 mass% uniform concentration distribution in the whole region.

[Production of Organic EL Element 14]
In the production of the organic EL element 6, an organic EL element 14 was produced in the same manner except that the following light emitting layer forming method 14 was used instead of the light emitting layer forming method 6.

(Method 14 of forming light emitting layer)
The light emitting layer is formed in the same manner as the light emitting layer forming method 6 except that the substrate and each evaporation source surface are arranged in parallel as shown in FIG. Method 14 was adopted. The blue light emitting dopant concentration profile of the formed light emitting layer is shown in d) of FIG.

Note that the green light-emitting dopant (compound B) and the red light-emitting dopant in the light-emitting layer 14 have a uniform concentration distribution of 0.2 mass% over the entire area.

<< Evaluation of organic EL elements >>
(Concentration evaluation by TOF-SIMS)
The concentration of the blue light-emitting dopant by TOF-SIMS was measured using a time-of-flight secondary ion mass spectrometer TRIFT2 manufactured by Physical Electronics, using In ions with an acceleration voltage of 25 kV (beam current is 2 nA) as primary ions. The density | concentration of each material from the anode side edge part of a light emitting layer to the cathode side edge part was measured. The obtained results are shown in FIGS.

(Measurement of power efficiency)
Using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing Co., Ltd.), the front luminance and luminance angle dependency of each organic EL element were measured, and the power efficiency at a front luminance of 1000 cd / m ² was obtained. Table 2 shows the relative values when the power efficiency of the organic EL element 3 is 100.

(Measurement of driving life)
The luminance fluctuation at the time of continuous driving was measured with the front luminance of 10,000 cd / m ² as the initial luminance, and the luminance half time was obtained as the driving life. Table 2 shows the relative values when the driving life of the organic EL element 3 is 100.

Table 2 shows the results obtained.

As is clear from the results shown in Table 2, the organic EL element having the light emitting layer having the structure defined in the present invention has a power efficiency and a driving life as compared with the comparative organic EL elements 1 to 3, 12, and 13. It turns out that it is excellent.

1

Deposition source

2, 2A,

2B Deposition head

3, 3A, 3B Nozzle 5, 9 Conduit 10

Control valve

11, 12 Deposition area G Gas H Heating member P Substrate 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen gas 109 Water catching agent

Claims

In the method of manufacturing an organic electroluminescent element, the organic compound is deposited from a plurality of vapor deposition sources filled with the organic compound on the moving substrate to form a light emitting layer of the organic electroluminescent element.
1) Each of the plurality of vapor deposition sources is filled with a host compound and a dopant compound,
2) The plurality of vapor deposition sources have different mass ratios of the dopant compound to the host compound,
3) The area where the vapor deposition areas of the plurality of vapor deposition sources overlap on the substrate is 10% or more of the total vapor deposition area,
The manufacturing method of the organic electroluminescent element characterized by these.
The method for producing an organic electroluminescence element according to claim 1, wherein all of the dopant compounds filled in the plurality of vapor deposition sources are the same.
3. The method of manufacturing an organic electroluminescence element according to claim 1, wherein the host compounds filled in the plurality of vapor deposition sources are all the same.
4. The method of manufacturing an organic electroluminescence element according to claim 1, wherein at least one of the vapor deposition sources contains a plurality of dopant compounds.
The dopant compound is a blue light emitting dopant, a green light emitting dopant, and a red light emitting dopant, and the concentration of the blue light emitting dopant in the plurality of vapor deposition sources is different, and the blue light emitting dopant has a gradient concentration in the thickness direction in the light emitting layer. It has, The manufacturing method of the organic electroluminescent element of any one of Claim 1 to 4 characterized by the above-mentioned.
The dopant compound is a blue light-emitting dopant, a green light-emitting dopant, and a red light-emitting dopant, and the concentrations of the green light-emitting dopant and the red light-emitting dopant in the plurality of vapor deposition sources are equal, and the green light-emitting dopant and the red light-emitting in the light-emitting layer. The method for producing an organic electroluminescent element according to claim 1, wherein the concentration of the dopant is uniform in the thickness direction.
The method for manufacturing an organic electroluminescence element according to any one of claims 1 to 6, wherein a surface of the vapor deposition source with respect to a discharge normal is non-parallel to the substrate surface.
The manufacturing method of the organic electroluminescent element according to claim 1, wherein the intersection points on the substrate where the discharge normals of the plurality of vapor deposition sources and the substrate surface intersect with each other are different. Method.