JP2012022884A - Manufacturing method of organic electroluminescent element, organic electroluminescent element, organic el lighting device, and organic el display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic electroluminescent element capable of stably manufacturing the organic electroluminescent element with high performance without deterioration of performance of the element obtained even after a certain period of time elapses before forming upper layer after forming luminescent layer, in a manufacturing process.SOLUTION: A manufacturing method of an organic electroluminescent element which includes a first electrode, luminescent layer and second electrode in this order comprises the step of, after luminescent layer formation, forming a layer corresponding to the upper layer of the luminescent layer after heat treatment of the luminescent layer after elapse of six hours or more after forming the luminescent layer.

Description

  The present invention relates to a method for producing an organic electroluminescent element, an organic electroluminescent element using the same, and an application thereof.

In recent years, electroluminescent elements using organic layers (organic electroluminescent elements; hereinafter also referred to as “organic EL elements” as appropriate) have been developed. Examples of the method for forming the organic layer in the organic electroluminescence device include a vacuum deposition method and a wet film formation method.
Since the vacuum deposition method is easy to stack, it has an advantage that the charge injection from the anode and / or the cathode is improved, and the exciton light-emitting layer is easily contained. On the other hand, the wet film formation method does not require a vacuum process, is easy to increase in area, and can be easily mixed with a plurality of materials having various functions in one layer (coating liquid). There is.

JP 2006-257409 A

In general, an organic electroluminescent element has a plurality of organic layers between a pair of electrodes. However, when an organic electroluminescent element is manufactured by an industrial process, the organic electroluminescent element is not less than a certain value during the lamination process due to various circumstances. It is expected that there will be a case where time work must be interrupted. For example, in the case of forming an upper layer (that is, a layer provided immediately in contact with a target layer (here, a light emitting layer) after a certain amount of time has elapsed after the light emitting layer is formed, When the light emitting layer is left standing (that is, after a certain period of time has elapsed after formation), the surface of the layer is roughened due to crystallization of the compound contained in the layer or other reasons, and the flatness is impaired. There is.
An element having such a light emitting layer cannot obtain uniform light emission, and tends to cause a reduction in light emission efficiency and driving life. According to the study by the present inventors, the above phenomenon is often observed on the surface of the light emitting layer when 6 hours or more have elapsed since the formation of the light emitting layer.

As a result of intensive studies to solve the above-mentioned problem, the present inventors solve the above-mentioned problem by providing an upper layer after the heat treatment is performed on the light-emitting layer after a certain time has elapsed after formation. I found out. By performing the heat treatment, the unevenness generated on the surface of the light emitting layer is reduced, and the resulting driving life of the device can be avoided.
That is, the present invention is a method for producing an organic electroluminescent device comprising a first electrode, a light emitting layer, and a second electrode in this order. The present invention resides in a method for manufacturing an organic electroluminescent element, wherein a layer corresponding to an upper layer of the light emitting layer is formed after the heat treatment.

Another gist of the present invention resides in an organic electroluminescent device manufactured by the above-described organic electroluminescent device manufacturing method.
Still another subject matter of the present invention resides in an organic EL illumination and an organic EL display device having the organic electroluminescent element manufactured by the method for manufacturing an organic electroluminescent element.

  According to the present invention, in the manufacturing process of the organic electroluminescent element, even when a certain time or more has elapsed from the formation of the light emitting layer to the formation of the upper layer, the performance of the obtained element is not reduced, A high-performance organic electroluminescence device can be stably produced. As a result, the process margin is widened, which is very useful in the industrial production of organic electroluminescent devices.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention. It is sectional drawing which shows typically the other example of the structure of the organic electroluminescent element of this invention.

The present invention will be described in detail below, but the present invention is not limited to the following description, and various modifications can be made without departing from the scope of the invention.
The method for producing an organic electroluminescent element of the present invention (hereinafter also referred to as “organic EL element” as appropriate) produces an organic electroluminescent element having a first electrode, a light emitting layer, and a second electrode in this order. It is a method to do.
One of the “first electrode” and the “second electrode” represents an “anode” and the other represents a “cathode”. It can be appropriately selected according to the desired element configuration.
That is, the organic electroluminescent element manufactured by the present invention includes an anode, a cathode formed so as to face the anode, and a light emitting layer formed between the anode and the cathode. Usually, in addition to the light emitting layer, for example, a hole transport layer, a hole injection layer, an electron transport layer, an electron transport layer, and the like may be provided between the anode and the cathode. There is no particular limitation on the method of forming these layers (hereinafter sometimes referred to as “organic layers”), and the layers can be formed by any method such as vapor deposition or wet film formation.

  In the method for producing an organic EL element of the present invention, a light emitting layer is treated by a specific method among the organic layers formed between the anode and the cathode. That is, after the formation of the light emitting layer, the light emitting layer is subjected to a heat treatment after a lapse of a certain time. In addition, there is no restriction | limiting in particular in the film-forming method of a light emitting layer, For example, it can form by any methods, such as a vapor deposition method and a wet film-forming method.

  When the upper layer is formed after a certain amount of time has elapsed after the formation of the light emitting layer, the left light emitting layer has a rough or uneven surface due to crystallization of the compound contained in the layer or other reasons. In some cases, flatness may be impaired. An element having such a light emitting layer cannot obtain uniform light emission, and tends to cause a reduction in light emission efficiency and driving life. According to the study by the present inventors, the above phenomenon is often observed on the surface of the light emitting layer when 6 hours or more have elapsed since the formation of the light emitting layer.

On the other hand, it discovered that the said problem was solved by providing an upper layer after heat-processing about the light emitting layer to which the fixed time passed after formation. By performing the heat treatment, the unevenness generated on the surface of the light emitting layer is reduced, and the driving life of the resulting element can be avoided.
Although details of the mechanism of the effect are unknown, it is presumed that flattening proceeds by heating each component in the layer uniformly re-dispersed by heating.
Hereinafter, the light emitting layer forming / processing method in the manufacturing method of the organic EL device of the present invention will be described, and then the organic EL device manufactured by the present invention will be described.

1. Light-Emitting Layer Formation / Treatment Method The light-emitting layer formation / treatment method of the present invention is characterized in that a heat treatment step of the light-emitting layer is provided after the emissive layer is formed and after 6 hours or more have elapsed and before the upper layer is formed.
The light emitting layer forming / processing method may include other processes as appropriate in addition to the film forming process, the storage process, and the heat treatment process described in detail below. Examples of other processes include a pretreatment process, a drying process, and a cooling process described below.
Hereinafter, although each process in a light emitting layer formation and a processing method is demonstrated, a pre-processing process and a cooling process shall be performed as needed.

1-1. Pretreatment step Before the light emitting layer is formed, a pretreatment step for removing impurities adhering to the formation surface (for example, the first electrode) can be performed. Thereby, an ionization potential can be adjusted and the hole or electron injection property to a light emitting layer can be improved. As a pretreatment method, for example, when the light emitting layer is formed on the first electrode, the surface is cleaned with an alcohol or the like, treated with ultraviolet rays (UV) / ozone, oxygen plasma, argon A plasma treatment method is preferable.

  It should be noted that the layer to be the formation surface of the light emitting layer, that is, the type of the lower layer formed adjacent to the light emitting layer is appropriately selected according to the structure of the organic EL element and the formation method of this layer is not particularly limited. For example, it may be a layer formed by a vapor deposition method, or may be a layer formed by a wet film formation method.

1-2. Film-forming process The film-forming process can be carried out by arbitrarily selecting means as long as the effects of the present invention are not significantly impaired. For example, a vacuum deposition method or a wet film-forming method can be used.
As a method of forming a light emitting layer by a vacuum deposition method, first, one or more materials for forming a light emitting layer are put in a crucible installed in a vacuum vessel (if two or more materials are used, Then, the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. After that, the crucible is heated (each crucible is heated when two or more materials are used), and the evaporation amount is controlled to evaporate (when two or more materials are used, the evaporation amount is independently controlled and evaporated). And a thin film of the material can be formed on a substrate placed facing the crucible. In addition, when using 2 or more types of materials, those mixtures can be put into a crucible, and it can heat and evaporate, and can also form the light emitting layer which consists of a mixture.

  On the other hand, when the light emitting layer is formed by a wet film forming method, a composition containing the material of the light emitting layer and a solvent (hereinafter sometimes referred to as “coating composition”) is applied and formed into a film shape. To form a film and dry it. Hereinafter, a solvent used when the light emitting layer is formed by a wet film forming method, a film forming method, film forming conditions (film forming humidity, oxygen concentration, number of particles, etc.), a drying method, and the like will be described.

(1-2-1) Solvent The solvent used in the coating composition is not limited as long as the effects of the present invention are not significantly impaired, and examples thereof include n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane. Alkanes; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxy Aromatic ethers such as benzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenylether; phenyl acetate, phenylpropionate, Benzoic acid Aromatic esters such as chill, ethyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, alicyclic ketones such as cyclohexanone, cyclooctanone, and Fencon; alicyclic rings such as cyclohexanol and cyclooctanol Aliphatic alcohols such as methyl ethyl ketone and dibutyl ketone; aliphatic alcohols such as butanol and hexanol; aliphatics such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and propylene glycol-1-monomethyl ether acetate (PGMEA) Ethers; and the like.

Of these, alkanes and aromatic hydrocarbons are preferable.
One of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.
The boiling point of the solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 200 ° C. or higher. The boiling point is usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower. Below this range, film formation stability may be reduced by evaporation of the solvent from the composition during wet film formation.

  Further, the concentration of the material of the light emitting layer in the coating composition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.1% by weight or more, and more preferably. Is 0.5% by weight or more. Moreover, it is 70 weight% or less normally, Preferably it is 60 weight% or less, More preferably, it is 50 weight% or less. If the concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the film.

  In addition, since the organic EL element is usually formed by laminating layers (organic layers) made of a large number of organic compounds, each layer is preferably a uniform layer. Here, when a layer is formed by a wet film formation method, if there is a certain amount or more of moisture in the composition for forming each organic layer, moisture is mixed into the coating film and the durability of the film is impaired. The water content in the solution is preferably as low as possible. In general, the organic EL element uses many materials such as a cathode whose function is remarkably deteriorated due to moisture, so that the presence of moisture is preferably as small as possible from the viewpoint of reducing the function of the element. For the above reasons, the amount of water contained in the coating composition is usually 1% by weight or less, preferably 0.1% by weight or less.

(1-2-2) Film Forming Method The film forming method in the case where the light emitting layer is formed by the wet film forming method does not significantly impair the effects of the present invention as long as it can be applied uniformly to the target region. There is no limit. For example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, ink jet method, screen printing method, nozzle coating method, gravure printing method, flexographic printing Law, etc.
Among these film forming methods, a spin coating method, a spray coating method, an ink jet method, and a nozzle coating method are preferable. This is because the liquid property specific to the coating composition used in the organic EL element is met.

(1-2-3) Film formation conditions (Film formation temperature)
The film forming temperature in the environment where the film forming process is performed by the wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, and preferably 13 ° C. or higher in terms of easy control of the drying rate. Is more preferable, and 16 ° C. or higher is even more preferable. Moreover, 50 degrees C or less is preferable and 40 degrees C or less is more preferable.

(Deposition humidity)
The relative humidity in the environment in which the film forming process is performed is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, and usually 80% or less, preferably 60% or less, more preferably 15% or less, More preferably, it is 1% or less, and particularly preferably 100 ppm or less. If the relative humidity is too low, it may be difficult to control film formation conditions during wet film formation. On the other hand, if it is too large, moisture adsorption on the organic layer may be easily affected.

(Oxygen concentration)
The volume concentration of oxygen in the environment in which the film forming process is performed by the wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 0.01 ppm or more, preferably 50% or less, more preferably 25. % Or less, more preferably 1% or less, and particularly preferably 100 ppm or less. An environment in which the oxygen concentration is too low is difficult to control, and if the oxygen concentration is too high, oxygen diffuses inside the light emitting layer, which may affect device characteristics.

(1-2-4) Drying The light emitting layer is usually dried after film formation by a wet film formation method. As long as the effect of the present invention is not significantly impaired, drying of the light emitting layer can be carried out with arbitrary changes. However, drying means a step of removing the solvent in the coating composition formed by the wet film forming method.

(Dry method)
The drying method at the time of drying is not limited as long as the effects of the present invention are not significantly impaired, and examples thereof include heat treatment, reduced pressure treatment, inert gas treatment, and sputtering treatment. Of these, heat treatment is preferred because it is easy to reduce the residual solvent in the film.
The above processing may be performed alone or in combination. When combining a plurality of processes, the processes may be performed in an arbitrary order, or all or a part of the processes may be performed in parallel. However, it is preferable to perform drying under conditions that reduce drying unevenness.

(Drying temperature)
The drying temperature at the time of drying is not limited as long as the effects of the present invention are not significantly impaired. However, in the case of performing heat treatment, among the materials (solid content) constituting the light emitting layer, the compound having the lowest glass transition point (Tg) is used. With respect to Tg, it is usually (Tg-80) ° C. or higher, preferably (Tg-50) ° C. or higher. Further, it is usually (Tg + 100) ° C. or lower, preferably (Tg + 50) ° C. or lower. By setting it to the upper limit or less, decomposition and alteration of the compound contained in the layer can be sufficiently avoided, and by setting the upper limit or more, the solvent in the film can be effectively removed.

On the other hand, from the viewpoint of removing the solvent in the film, it is preferable to dry at a temperature equal to or higher than the boiling point of the solvent. Therefore, when drying by heat treatment, it is preferable to select the solvent used for the light emitting layer forming (coating) composition from those having a boiling point lower than the upper limit of the drying temperature.
The drying temperature means an environmental temperature in the case of an in-furnace baking method, a plate temperature in the case of a hot plate method, and an environmental temperature in the case of a method using a heater.
When drying is performed by heat treatment, a cooling step may be provided thereafter if necessary.

(Drying time)
The drying time at the time of drying is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 30 seconds or more, more preferably 1 minute or more, and further preferably 2 minutes or more. Further, it is preferably 5 hours or less, more preferably 2 hours or less, and further preferably 1 hour or less. If the drying time is too long, the components of the layers other than the light emitting layer tend to diffuse, and if it is too short, the film tends to be inhomogeneous.

(Relative humidity)
The relative humidity at the time of drying is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, and usually 80% by weight or less, preferably 60% by weight or less, more preferably 15% by weight or less. More preferably, it is 1% by weight or less, particularly preferably 100 ppm or less. If the relative humidity is too high, moisture tends to remain in the film.

(Degree of vacuum)
The degree of vacuum at the time of drying is not limited as long as the effect of the present invention is not significantly impaired. However, in the case of performing a pressure reduction treatment, it is preferably 1000 Pa or less, more preferably 500 Pa or less, and further preferably 300 Pa or less. Moreover, although there is no restriction | limiting in a lower limit, it is 1 * 10 < ^-5 > Pa or more normally. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control tends to be difficult during that time. If it is too low, the solvent tends to remain in the film.

1-3. Storage process The present invention is a method for producing an organic electroluminescent element using a light emitting layer after a certain time has elapsed after formation. In the following description, the passage of a certain time or more is used for convenience. This is called “storage process”. In other words, the storage step means the time until the upper layer (another organic layer or electrode) is formed on the light emitting layer that has been subjected to the cooling step or the like after the formation in the film formation step. In addition to storage in a stationary state, storage in a transportation state such as transportation is also included. In addition, storing the light emitting layer includes storing the entire substrate on which the light emitting layer is formed.

(1-3-1) Storage period The storage period in the storage process is not particularly limited as long as the effect of the present invention is not significantly impaired, but is usually 6 hours or more, preferably 16 hours or more, more preferably 1 day or more. . Moreover, it is 30 days or less normally, Preferably it is 10 days or less, More preferably, it is 4 days or less. If this upper limit is exceeded, the amount of moisture and volatile organic substances adsorbed on the light-emitting layer increases in addition to crystallization of the compound contained in the light-emitting layer and other reasons, which is necessary for the heat treatment step described later. The heating time required for this may increase, and the material constituting the light emitting layer may be affected. Moreover, the effect of this invention is easy to be acquired when it is more than the said lower limit.

(1-3-2) Storage humidity The relative humidity in the storage process is not particularly limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, and usually 80% by weight or less, preferably 60% by weight. Hereinafter, it is more preferably 15% by weight or less, further preferably 1% by weight or less, and particularly preferably 100 ppm or less. When the above upper limit is exceeded, the amount of moisture adsorbed on the light emitting layer increases, so that the heating time required for the heat treatment step described later becomes longer, which may affect the material constituting the light emitting layer. There is sex.

(1-3-3) Storage Environment The environment in the storage process is not particularly limited as long as the effects of the present invention are not significantly impaired, and the temperature during storage is usually 4 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 It can be set to at least ° C. Moreover, it is 90 degrees C or less normally, Preferably it is 70 degrees C or less, More preferably, it is 40 degrees C or less. As a result, the device can be stored in a stable environment. The atmosphere is usually an inert gas environment, but may be a vacuum environment, a dry air environment, or the atmosphere.

1-4. Heat treatment step The heat treatment step in the present invention is a step of heat-treating the light-emitting layer after the storage step and before forming a new organic layer or electrode on the light-emitting layer. The heat treatment can be carried out by arbitrarily changing unless the effects of the present invention are impaired.

(1-4-1. Heating means)
As a specific method of the heating means, for example, a hot plate method in which a substrate having a light emitting layer formed on a plate (hot plate) is mounted and the light emitting layer is heated through the plate, the upper surface side of the light emitting layer and / or Alternatively, a method in which a heater is disposed on the lower surface side (base material side) and the light emitting layer is heated by irradiating electromagnetic waves (for example, infrared rays) from the heater can be used. Of these, the plate (hot plate) method is preferable. This is because the light emitting layer can be uniformly heated, and moisture adsorbed in the light emitting layer, volatile organic substances, and the like can be removed. One heating means may be used, or two or more heating means may be used in any combination and ratio.

(1-4-2) Heating temperature The heating temperature in the heat treatment step is not limited as long as the effects of the present invention are not significantly impaired, but the glass transition point (Tg) is the most among the materials (solid content) constituting the light emitting layer. Is usually (Tg-30) ° C. or higher, preferably (Tg-20) ° C. or higher, with respect to Tg of a compound having a low A. Further, it is usually (Tg + 50) ° C. or lower, preferably (Tg + 40) ° C. or lower. By setting it to the upper limit value or less, decomposition or alteration of the compound contained in the light emitting layer can be sufficiently avoided, and setting it to the lower limit value or more is preferable because the surface flattening effect of the light emitting layer is sufficiently manifested.

(1-4-3) Heating time Although the heat processing time in a heat processing process is not restrict | limited unless the effect of this invention is impaired remarkably, Preferably it is 1 minute or more, More preferably, it is 5 minutes or more. Moreover, Preferably it is 5 hours or less, More preferably, it is 3 hours or less. For the purpose of promoting flattening, there is no upper limit on the heating time, but by setting it to the upper limit or less, diffusion of components of other layers to the light emitting layer can be suppressed, and by setting it to the upper limit or more, light emission Since the planarization of the layer surface becomes more remarkable, it is preferable.

(1-4-4) Humidity The relative humidity in the heat treatment step is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, and usually 80% by weight or less, preferably 60% by weight or less, More preferably, it is 15 weight% or less, More preferably, it is 1 weight% or less, Most preferably, it is 100 ppm or less. If the relative humidity is too high, moisture remains in the light emitting layer, and the effects of the present invention may not be sufficiently obtained.

(1-4-5) Degree of vacuum The degree of vacuum in the heat treatment step is not limited as long as the effects of the present invention are not significantly impaired. However, in the case of performing a decompression treatment, it is preferably 1000 Pa or less, more preferably 500 Pa or less. Preferably it is 300 Pa or less. Moreover, although there is no restriction | limiting in a lower limit, it is 1 * 10 < ^-5 > Pa or more normally. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control during that time tends to be difficult, and if it is too low, solvents, moisture, etc. tend to remain in the light emitting layer. There is.

1-6. Other Steps In the light emitting layer formation / treatment method, steps other than the above may be included before and after each step or during the steps, as necessary.
2. Organic Electroluminescent Device Hereinafter, the organic EL device according to the present invention will be described. The organic EL device according to the present invention includes at least the light emitting layer forming / processing method in its manufacturing process. As an organic EL device manufactured by such a method, a substrate is usually provided, a first electrode is formed on the substrate, one or more organic layers are formed thereon, and the organic layer is further formed on the organic layer. It has a stacked structure in which a second electrode is formed. Here, one of the first electrode and the second electrode is an anode, and the other is a cathode. At least one of the organic layers is a light emitting layer, and examples of other organic layers include a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and an electron blocking layer. And the like.

In addition, for the purpose of further improving the efficiency of hole or electron injection and improving the adhesion between the whole organic layer and the first electrode, a known buffer layer or the like between the first electrode and the organic layer May be formed.
Hereinafter, the case where the first electrode is an anode and the second electrode is a cathode will be described in the order of stacking from the substrate side. FIG. 1 is a cross-sectional view schematically showing an example of the structure of an organic EL device manufactured according to the present invention. An organic EL element 10a shown in FIG. 1 is configured by laminating an anode 2, a hole injection layer 3, a light emitting layer 5, an electron transport layer 7, an electron injection layer 8, and a cathode 9 in this order on a substrate 1. Is done.
Hereinafter, each of these components will be described.

2-1. Substrate The substrate 1 serves as a support for the organic EL element 10a, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, it is preferable to use a transparent substrate made of a general-purpose material such as a glass plate, a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone.

  Examples of the material of the substrate 1 include various types of shot glass such as BK7, SF11, LaSFN9, BaK1, and F2, synthetic phased silica glass, optical crown glass, low expansion borosilicate glass, sapphire glass, soda glass, and alkali-free glass. Glass, TFT-formed glass, and polymer materials include acrylic resins such as polymethylmethacrylate and cross-linked acrylate, aromatic polycarbonate resins such as bisphenol A polycarbonate, polyester resins such as polyethylene terephthalate, and polycycloolefins. Examples thereof include crystalline polyolefin resins, epoxy resins, styrene resins such as polystyrene, polysulfone resins such as polyethersulfone, and synthetic resins such as polyetherimide resin. Moreover, 2 or more types of laminated bodies may be sufficient among these. Depending on the purpose and application, an optical film such as an antireflection film, a circularly polarizing film, or a retardation film may be formed on or bonded to these substrates.

  However, it is preferable to pay attention to gas barrier properties when using a synthetic resin substrate. This is because if the gas barrier property of the substrate 1 is too small, the performance of the organic EL element 10a may be deteriorated by the outside air that has passed through the substrate 1. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

2-2. An anode 2 is provided on the anode substrate 1. The anode 2 plays a role of injecting holes into a layer (such as the hole injection layer 3 or the light emitting layer 5) on the light emitting layer 5 side.
This anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; a carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline. In addition, only 1 type may be used for the material of the anode 2, and 2 or more types may be used together by arbitrary combinations and a ratio.

  Although there is no restriction | limiting in the formation method of the anode 2, Usually, it carries out by sputtering method, a vapor deposition method, etc. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing them and applying them onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

In addition, the anode 2 is usually a single layer structure, but may be a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more. Also, it is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when the anode 2 may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Further, it is possible to laminate different conductive materials on the anode 2.

Further, for the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is subjected to ultraviolet (UV) / ozone treatment, oxygen plasma, argon plasma. It is preferable to process.
Furthermore, as described above, a known anode is provided between the hole injection layer 3 and the anode 2 for the purpose of further improving the efficiency of hole injection and improving the adhesion of the whole organic layer to the anode. A buffer layer may be inserted.

2-3. Hole Injection Layer The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5. Usually, this hole injection layer 3 is formed on the anode 2. Therefore, the hole injection layer 3 is preferably configured to contain a hole injection compound and an electron accepting compound. Furthermore, the hole injection layer 3 may contain other components without departing from the spirit of the present invention.

  Examples of the method for forming the hole injection layer 3 on the anode 2 include a wet film formation method and a vacuum deposition method. However, a uniform and defect-free thin film can be easily obtained, and the formation time is short. In view of this, the wet film forming method is preferable. ITO (indium tin oxide) generally used as the anode 2 has a surface roughness (Ra) of about 10 nm in addition to its surface, and often has local protrusions, and short-circuit defects. There was a problem that it was easy to produce. Forming the hole injection layer 3 on the anode 2 by the wet film formation method reduces the occurrence of device defects due to the unevenness of the surface of the anode 2 as compared with the case of forming by the vacuum deposition method. It also has advantages.

(Hole injection compound)
Examples of the hole-injecting compound include aromatic amine compounds. Among them, compounds containing a triarylamine structure are preferable, but compounds that have been conventionally used as a material for forming a hole-injecting layer in an organic electroluminescence device are used. You may select from the inside suitably. As an aromatic amine compound, the binaphthyl type compound represented by following General formula (1) is mentioned, for example.

In the general formula (1), Ar ^{a to} Ar ^d are each independently a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic monocyclic group or condensed ring group which may have a substituent. Ar ^a and Ar ^b , Ar ^c and Ar ^d may be bonded to each other to form a ring. W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. X ¹ and X ² each independently represent a direct bond or a divalent linking group. Further, a naphthalene ring in the general formula ^(1), - (X 1 ^NAr a Ar ^b) and ^- in addition to the ^{(X 2 NAr c Ar d)} , may have an arbitrary substituent.

In the general formula (1), as the monocyclic group or condensed ring group of a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring which may have a substituent of Ar ^{a to} Ar ^d , respectively. Independently, for example, a 5- or 6-membered monocyclic ring or a 2-3 condensed ring, specifically, a group derived from an aromatic hydrocarbon ring such as a phenyl group, a naphthyl group, an anthryl group; a pyridyl group, a thienyl group A group derived from an aromatic heterocycle such as Any of these may have a substituent.

As the substituent that Ar ^{a to} Ar ^d may have, those described later as the substituent that Ar ^{e to} Ar ^l may have, and an arylamino group (that is,-(NAr ^e Ar ^f ) described later, -(Corresponding to NAr ^g Ar ^h )).
Ar ^a and Ar ^b and / or Ar ^c and Ar ^d may be bonded to each other to form a ring. In this case, specific examples of the ring to be formed include a carbazole ring, a phenoxazine ring, an iminostilbene ring, a phenothiazine ring, an acridone ring, an acridine ring, an iminodibenzyl ring and the like that may have a substituent. Of these, a carbazole ring is preferred.

In the general formula (1), W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. Particularly preferred are W1 = 1 and W2 = 1. The arylamino groups in the case where W1 and / or W2 is 2 or more may be the same or different.
X ¹ and X ² each independently represent a direct bond or a divalent linking group. Although there is no restriction | limiting in particular as a bivalent coupling group, For example, what is shown below etc. are mentioned. A direct bond is particularly preferable as X ¹ and X ² .

In addition to — (X ¹ NAr ^a Ar ^b ) and — (X ² NAr ^c Ar ^d ), the naphthalene ring in the general formula (1) has one or more arbitrary substituents at an arbitrary position. It may be. Preferred examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and an alkenyl group which may have a substituent. , One or more substituents selected from the group consisting of optionally substituted alkoxycarbonyl groups. Of these, an alkyl group is particularly preferred.

As the binaphthyl compound represented by the general formula (1), a binaphthyl compound in which Ar ^a and Ar ^c are each further substituted with an arylamino group is preferable, as represented by the following general formula (1-1). .

(In the general formula (1-1), Ar ^{e to} Ar ¹ each independently represents a 5- or 6-membered aromatic hydrocarbon ring or aromatic monocyclic group which may have a substituent, or Represents a condensed ring group, Ar ^e and Ar ^f , Ar ^g and Ar ^h may be bonded to each other to form a ring, and W 1 and W 2 have the same meanings as in general formula (1), X ¹ and X ² has the same meaning as in general formula (1).)

The naphthalene ring in the general formula (1-1) includes substituents — (X ¹ NA Ar ⁱ Ar ^j NAr ^f Ar ^e ) and — (X ² NAr ^k Ar ^l NAr ^g ) each containing an arylamino group bonded to the naphthalene ring. In addition to Ar ^h ), it may have an arbitrary substituent. In addition, these substituents — (X ¹ NA ⁱ Ar ^j NAr ^f Ar ^e ) and — (X ² NAr ^k Ar ^l NAr ^g Ar ^h ) have a substituent at any substitution position of the naphthalene ring. Also good. Especially, the binaphthyl type compound substituted to 4-position and 4'-position of the naphthalene ring in General formula (1-1) respectively is more preferable.

  Moreover, as a high molecular compound which has a positive hole transport site | part in a molecule | numerator used as a hole injectable compound, the high molecular compound which contains an aromatic tertiary amino group in a main skeleton as a structural unit is mentioned, for example. Specific examples thereof include a hole injecting compound having a structure represented by the following general formula (2) as a repeating unit.

(In formula (2), Ar ^{44 to} Ar ⁴⁸ each independently represent a divalent aromatic ring group which may have a substituent, and R ^a31 and R ^a32 each independently represent a substituent. And Q is selected from a direct bond or the following linking group, wherein “aromatic ring group” means “derived from an aromatic hydrocarbon ring” Including "group" and "group derived from an aromatic heterocycle")

(In formula (3), Ar ⁴⁹ represents a divalent aromatic ring group which may have a substituent, and Ar ⁵⁰ represents a monovalent aromatic ring group which may have a substituent. .)
In the general formula (2), Ar ^{44 to} Ar ⁴⁸ are each preferably a group derived from a divalent benzene ring, naphthalene ring, anthracene ring or biphenyl group which may each independently have a substituent, A group derived from a benzene ring is preferred. Examples of the substituent include a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; and a C 2-7 such as a methoxycarbonyl group and an ethoxycarbonyl group. A linear or branched alkoxycarbonyl group of 1 to 6 carbon atoms such as a methoxy group or an ethoxy group; an aryloxy group of 6 to 12 carbon atoms such as a phenoxy group or a benzyloxy group; And a dialkylamino group having an alkyl chain having 1 to 6 carbon atoms such as a diisopropylamino group. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable. The case where Ar ^{44 to} Ar ⁴⁸ are all unsubstituted aromatic ring groups is particularly preferable.

R ^a31 and R ^a32 are preferably each independently a phenyl group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, or biphenyl group that may have a substituent. Preferably a phenyl group, a naphthyl group or a biphenyl group, more preferably a phenyl group. Examples of the substituent include a group in which an aromatic ring in Ar ⁴⁴ to Ar ⁴⁸ may have include the same groups as previously described.

In the general formula (3), Ar ⁴⁹ is a divalent aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability. Includes a divalent benzene ring, naphthalene ring, anthracene ring-derived group, biphenylene group, and terphenylene group which may have a substituent. Further, examples of the substituent include a group in which an aromatic ring may have at Ar ⁴⁴ to Ar ^48, include the same groups as previously described. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable.

Ar ⁵⁰ is an aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability, and specifically, phenyl which may have a substituent. Group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, biphenyl group and the like. As this substituent, the group similar to the group mentioned above is mentioned as a group which the aromatic ring in Ar < ⁴⁴ > -Ar < ⁴⁸ > of General formula (2) may have.

In the general formula (3), it is particularly preferable that Ar ⁴⁹ and Ar ⁵⁰ are both unsubstituted aromatic ring groups.
Examples of the hole injecting compound including an aromatic tertiary amino group as a side chain include compounds having a repeating unit having a structure represented by the following general formulas (4) and (5).

(In formula (4), Ar ⁵¹ represents a divalent aromatic ring group which may have a substituent, and Ar ^{52 to} Ar ⁵³ may each independently have a substituent 1. R ^{a33 to} R ^a35 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a monovalent aromatic ring group which may have a substituent. .)

(In the formula (5), Ar ^{54 to} Ar ⁵⁸ each independently represent a divalent aromatic ring group which may have a substituent, and R ³⁶ and R ³⁷ each independently represent a substituent. And Y is selected from a direct bond or the following linking group.)

In the general formula (4), Ar ⁵¹ is preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group each optionally having a substituent. For example, examples of the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ in the general formula (2) described above may have include the same groups as those described above, and preferred groups are also the same.
Ar ⁵² and Ar ⁵³ are preferably each independently a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, and a biphenyl group. May have. Examples of the substituent include the same groups as those described above as the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of the general formula (2) may have, and preferred groups are also the same.

R ^{a33 to} R ^a35 are preferably each independently a hydrogen atom; a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group; a carbon such as a methoxy group or an ethoxy group; A linear or branched alkoxy group of 1 to 6; a phenyl group; or a tolyl group.
In the general formula (5), Ar ^{54 to} Ar ⁵⁸ are preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group, each of which may have a substituent. A group derived from a benzene ring. Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

R ³⁶ and R ³⁷ are each preferably a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, or a biphenyl group, each of which may have a substituent. . Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

  Preferred examples of the structures represented by the general formulas (2) to (5) are shown below, but are not limited thereto.

  The hole injecting compound which is a polymer compound having a hole transporting site in the molecule is particularly preferably a homopolymer having a structure represented by any one of the general formulas (2) to (5). It may be a copolymer (copolymer) with any monomer. When it is a copolymer, it is preferable to contain 50 mol% or more, especially 70 mol% or more of the structural units represented by the general formulas (2) to (5). In addition, the hole injectable material which is a high molecular compound may contain multiple types of structures represented by the general formulas (2) to (5) in one compound. Moreover, you may use in combination of multiple types of the compound containing the structure represented by General formula (2)-(5). Of the general formulas (2) to (5), a homopolymer composed of a repeating unit represented by the general formula (2) is particularly preferable.

Examples of the hole injecting material made of a polymer compound further include conjugated polymers. For this purpose, polyfluorene, polypyrrole, polyaniline, polythiophene, polyparaphenylene vinylene are preferred.

(Electron-accepting compound)
The kind of the electron accepting compound used as the material for the hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. Examples thereof include onium salts substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pendafluorophenyl) borate and triphenylsulfonium tetrafluoroborate; No. 251067), high-valence inorganic compounds such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris (pendafluorophenyl) borane (JP-A-2003-31365); fullerene derivatives ; Iodine etc. are mentioned. Of the above compounds, an onium salt substituted with an organic group is preferable in terms of having strong oxidizing power, and an inorganic compound having a high valence is preferable, and an onium salt substituted with an organic group in terms of being soluble in various solvents, A cyano compound and an aromatic boron compound are preferable. Furthermore, an onium salt substituted with an organic group is particularly preferred from the viewpoint of achieving both strong oxidizing power and high solubility, and particularly preferred are compounds represented by the following formulas (II-1) to (II-3). .

(In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ each independently represents an arbitrary group, and two or more adjacent groups of R ^{11 to} R ³⁴ may be bonded to each other to form a ring. A ¹ -A ³ are all elements in the long period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to the long period type periodic table). there are, a ¹ represents an element belonging to group 17 of the periodic table, a ² represents an element belonging to group 16 of the periodic table, a ³ is .Z ₁ representing an element belonging to group 15 of the periodic table ^n1- to Z ₃ n ^3- each independently, _.n 1 ~n ₃ which represents a counter anion, each independently,
It represents the ionic value of the counter anion. )
In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. Therefore, the type of R ¹¹ , R ²¹ and R ³¹ is not particularly limited as long as it is an organic group having a carbon atom at the bonding portion with A ^{1 to} A ³ as long as it is not contrary to the gist of the present invention.

The molecular weights of R ¹¹ , R ²¹ and R ³¹ are each a value including the substituent, and are usually 1000 or less, preferably 500 or less.
Preferable examples of R ¹¹ , R ²¹ and R ³¹ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group from the viewpoint of delocalizing a positive charge. Among them, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it delocalizes positive charges and is thermally stable.

The alkyl group includes, for example, a linear, branched or cyclic alkyl group having a carbon number of usually 1 or more and usually 12 or less, preferably 6 or less. Specific examples include methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, isobutyl group, tert-butyl group, cyclohexyl group and the like.
Examples of the alkenyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less carbon atoms. Specific examples include a vinyl group, an allyl group, and a 1-butenyl group.

Examples of the alkynyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less. Specific examples include ethynyl group and propargyl group.
Examples of the aromatic hydrocarbon group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2 to 5 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include a monovalent group derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluorene ring, and the like. Can be mentioned.

  Examples of the aromatic heterocyclic group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, triazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, Pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline And monovalent groups derived from a ring, an isoquinoline ring, a sinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like.

In the above formulas (II-1) to (II-3), R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ each independently represents an arbitrary substituent. Therefore, the types of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are not particularly limited as long as they are not contrary to the spirit of the present invention.
The molecular weights of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are values including the substituents, and are usually 1000 or less, preferably 500 or less.

Examples of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, an amino group, an alkylamino group, and an arylamino group. , Acylamino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyloxy group, alkylthio group, arylthio group, sulfonyl group, alkylsulfonyl group, arylsulfonyl group, sulfonyloxy group, cyano Group, hydroxyl group, thiol group, silyl group and the like. Among them, like R ¹¹ , R ^21, and R ³¹ , an organic group having a carbon atom in the bonding portion with A ^{1 to} A ³ is preferable from the viewpoint of high electron acceptability. Examples include an alkyl group, an alkenyl group, Alkynyl groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups are preferred. In particular, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it has a large electron accepting property and is thermally stable.
Examples of the alkyl group, alkenyl group, alkynyl group, aromatic hydrocarbon group and aromatic heterocyclic group are the same as those described above for R ¹¹ , R ²¹ and R ³¹ .

As described above, the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ are further substituted with other substituents unless they are contrary to the spirit of the present invention. It may be. The type of the substituent is not particularly limited, and examples thereof include a halogen atom in addition to the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ . A cyano group, a thiocyano group, a nitro group, etc. are mentioned. Among these, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferable from the viewpoint of not hindering heat resistance and electron accepting property. In addition, the substituent to be further substituted may be substituted with only one, or two or more may be substituted with any combination and ratio.
In the formulas (II-1) to (II-3), two or more adjacent groups out of R ^{11 to} R ³⁴ may be bonded to each other to form a ring.

In formulas (II-1) to (II-3), A ^{1 to} A ³ are all elements after the third period (third to sixth periods) of the periodic table, and A ¹ is a long period type An element belonging to Group 17 of the periodic table is represented, A ² represents an element belonging to Group 16 and A ³ represents an element belonging to Group 15.

Among these, from the viewpoint of electron acceptability and availability, elements before the fifth period (third to fifth periods) of the periodic table are preferable. That is, A ¹ is preferably any ^one of an iodine atom, a bromine atom, and a chlorine atom, A ² is preferably any one of a tellurium atom, a selenium atom, and a sulfur atom, and A ³ is preferably an antimony atom, an arsenic atom, Any of the phosphorus atoms is preferred.
In particular, from the viewpoints of electron acceptability and compound stability, a compound in which A ¹ in formula (II-1) is a bromine atom or an iodine atom, or A ² in formula (II-2) is a selenium atom or a sulfur atom. Of these, a compound in which A ¹ in Formula (II-1) is an iodine atom is particularly preferable.

In formulas (II-1) to (II-3), Z ₁ ^{n1 to} Z ₃ ⁿ³ each independently represent a counter anion. The type of the counter anion is not particularly limited, and may be a monoatomic ion or a complex ion. However, the larger the size of the counter anion, the more the negative charge is delocalized, and the positive charge is also delocalized thereby increasing the electron accepting ability. Therefore, the complex ion is preferable to the monoatomic ion.

In formulas (II-1) to (II-3), n _{1 to} n ₃ are each independently any positive integer corresponding to the ionic value of the counter anion Z ₁ ^{n1 to} Z ₃ ⁿ³ . The values of n _{1 to} n ₃ are not particularly limited, but all are preferably 1 or 2, and particularly preferably 1.
Specific examples of Z ₁ ^{n1- to} Z ₃ ^n3- include hydroxide ions, fluoride ions, chloride ions, bromide ions, iodide ions, cyanide ions, nitrate ions, nitrite ions, sulfate ions, sulfite. Ion, perchlorate ion, perbromate ion, periodate ion, chlorate ion, chlorite ion, hypochlorite ion, phosphate ion, phosphite ion, hypophosphite ion, borate ion , Isocyanate ion, hydrosulfide ion, tetrafluoroborate ion, hexafluorophosphate ion, hexachloroantimonate ion; carboxylate ion such as acetate ion, trifluoroacetate ion, benzoate ion; methanesulfonate ion, trifluoro Sulfonate ions such as methane sulfonate ion; methoxy ions, t-butoxy ions, etc. Kokishiion and the like.

In particular, the counter anions Z ₁ ^{n1 to} Z ₃ ⁿ³ are preferably complex ions represented by the following formulas (II-4) to (II-6) from the viewpoint of stability of the compound and solubility in a solvent. In view of the large size, the negative charge is delocalized, and the positive charge is also delocalized to increase the electron accepting ability. Therefore, a complex ion represented by the following formula (II-6) is more preferable.

In formulas (II-4) and (II-6), E ¹ and E ³ each independently represent an element belonging to Group 13 of the long-period periodic table. Of these, a boron atom, an aluminum atom, and a gallium atom are preferable, and a boron atom is preferable from the viewpoint of stability of the compound and ease of synthesis and purification.
In formula (II-5), E ² represents an element belonging to Group 15 of the long-period periodic table. Among these, a phosphorus atom, an arsenic atom and an antimony atom are preferable, and a phosphorus atom is preferable from the viewpoint of stability of the compound, ease of synthesis and purification, and toxicity.

In the formulas (II-4) and (II-5), X represents a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, and is a fluorine atom in terms of stability of the compound, ease of synthesis and purification, A chlorine atom is preferable, and a fluorine atom is particularly preferable.
In the formula (II-6), Ar ^{61 to} Ar ⁶⁴ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group. Examples of the aromatic hydrocarbon group and aromatic heterocyclic group are the same as those exemplified above for R ¹¹ , R ²¹ and R ³¹ , derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. A monovalent group is mentioned. Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, or an isoquinoline ring is preferable from the viewpoint of stability and heat resistance of the compound.

The aromatic hydrocarbon group and aromatic heterocyclic group exemplified as Ar ^{61 to} Ar ⁶⁴ may be further substituted with another substituent as long as not departing from the gist of the present invention. The type of the substituent is not particularly limited, and any substituent can be applied, but an electron-withdrawing group is preferable.
Illustrative examples of preferred electron-withdrawing groups as the substituent that Ar ^{61 to} Ar ⁶⁴ may have include halogen atoms such as fluorine atom, chlorine atom and bromine atom; cyano group; thiocyano group; nitro group; mesyl group Alkylsulfonyl groups such as tosyl group; arylsulfonyl groups such as tosyl group; acyl groups such as formyl group, acetyl group, benzoyl group and the like, usually having 1 or more, usually 12 or less, preferably 6 or less; methoxycarbonyl group, ethoxycarbonyl An alkoxycarbonyl group having 2 or more carbon atoms, usually 10 or less, preferably 7 or less; a phenoxycarbonyl group, a pyridyloxycarbonyl group or the like, and usually having 3 or more carbon atoms, preferably 4 or more and usually 25 or less. Preferably an aryloxycarbonyl group having 15 or less aromatic hydrocarbon groups or aromatic heterocyclic groups; Carbonyl group; aminosulfonyl group; fluorine atom in a linear, branched or cyclic alkyl group having usually 1 or more, usually 10 or less, preferably 6 or less, such as trifluoromethyl group or pentafluoroethyl group And a haloalkyl group substituted with a halogen atom such as a chlorine atom.

Especially, it is more preferable that at least one group out of Ar ^{61 to} Ar ⁶⁴ has one or two or more fluorine atoms or chlorine atoms as a substituent. In particular, it is particularly a perfluoroaryl group in which all the hydrogen atoms of Ar ^{61 to} Ar ⁶⁴ are substituted with fluorine atoms from the viewpoint of efficiently delocalizing negative charges and having an appropriate sublimation property. preferable. Specific examples of the perfluoroaryl group include a pentafluorophenyl group, a heptafluoro-2-naphthyl group, and a tetrafluoro-4-pyridyl group.
In addition, as for the said substituent, only one may be substituted and two or more may be substituted by arbitrary combinations and ratios.

  The formula amount of the complex ions represented by the formulas (II-4) to (II-6) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 or more, preferably 300 or more, more preferably 400 or more. Moreover, it is usually 5000 or less, preferably 3000 or less, more preferably 2000 or less. If the formula amount of the complex ion is too small, delocalization of the positive charge and the negative charge is insufficient, so that the electron accepting ability may be decreased, and if the formula amount of the complex ion is too large, The compound itself may interfere with charge transport.

  As the material for the hole injection layer, any one of the various electron-accepting compounds described above may be used alone, or two or more may be used in any combination and ratio. When two or more kinds of electron-accepting compounds are used, two or more kinds of electron-accepting compounds corresponding to any one of the formulas (II-1) to (II-3) may be combined. Two or more electron-accepting compounds corresponding to different formulas may be combined.

  The content of the electron-accepting compound in the hole injection layer 3 and the composition for hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. The value relative to the pore-transporting compound is usually 0.1% by weight or more, preferably 1% by weight or more, and usually 100% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. A larger amount of the electron-accepting compound is preferable because it is easier to insolubilize, and the heating time can be insolubilized in a short time. In addition, when using together 2 or more types of electron-accepting compounds, it is made for the total content of these to be contained in the said range.

  In addition, when the hole injection layer 3 is formed or after the formation, the above hole transporting polymer or the following hole transporting compound reacts with the electron accepting compound, so that the hole injection after the formation is performed. In the layer 3, a cation radical and an ionic compound of a hole transporting polymer or a hole transporting compound may be generated.

(Low molecular weight hole transport compound)
As a material for the hole injection layer, it is preferable to use a low molecular weight hole transporting compound as necessary. The low molecular weight hole transporting compound can be appropriately selected from various compounds conventionally used as a hole injection / transport thin film purification material in an organic EL device. Among them, those having high solvent solubility are preferable.
Preferable examples of the low molecular weight hole transporting compound include aromatic amine compounds. Of these, aromatic tertiary amine compounds are particularly preferred.

The molecular weight of the low molecular weight hole transporting compound is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 200 or more, preferably 400 or more, more preferably 600 or more, and usually 5000 or less, preferably Is not more than 3000, more preferably not more than 2000, still more preferably not more than 1700, particularly preferably not more than 1400. If the molecular weight is too small, the heat resistance tends to be low, whereas if the molecular weight of the low molecular weight hole transporting compound is too large, synthesis and purification tend to be difficult.
In addition, a low molecular weight hole transportable compound may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

(Other ingredients)
As a material for the hole injection layer, in addition to the above-described polymer having a hole transporting property, an electron-accepting compound and a hole-transporting compound, as long as the effects of the present invention are not significantly impaired, it further contains other components. You may let them. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, coatability improving agents, and the like. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

(Formation of hole injection layer)
There is no restriction | limiting in particular in the formation method of a positive hole injection layer, It forms with a wet film-forming method or a vacuum evaporation method. In the case of forming by a wet film forming method, the above-described material is dissolved in an appropriate solvent to prepare a coating composition, and a film is formed using the composition. Hereinafter, although the case where a wet film-forming method is used is demonstrated to an example, it is not limited to this.

  As the hole injection layer solvent to be contained in the composition for hole injection layer, any solvent can be used as long as the hole injection layer 3 can be formed. However, among the aforementioned polymers, electron-accepting compounds, and low-molecular-weight hole-transporting compounds, those capable of dissolving at least one, particularly two or more, and particularly all three are preferable. Specifically, the solubility of the polymer is usually 0.005% by weight or more, particularly 0.5% by weight or more, particularly 1% by weight or more at room temperature and normal pressure. It is preferable to dissolve 0.001% by weight or more, especially 0.1% by weight or more, particularly 0.2% by weight or more.

In addition, as the solvent for the hole injection layer, a polymer, an electron-accepting compound, a low-molecular-weight hole-transporting compound, and an inactive substance that can deactivate a free carrier (cation radical) generated from a mixture thereof, or A solvent that does not contain a substance that generates a deactivating substance is preferred.
Suitable examples of the solvent for the hole injection layer are the same as those described in “1. Method for forming and treating light emitting layer”. However, aromatic hydrocarbon solvents such as benzene, toluene, and xylene have a low ability to dissolve the oxidant and the polymer, and are therefore preferably used in a mixture with an ether solvent and an ester solvent.

  The ratio of the hole injection layer solvent to the hole injection layer composition is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50%. It is in the range of not less than weight, usually not more than 99.999% by weight, preferably not more than 99.99% by weight, and more preferably not more than 99.9% by weight. In addition, when mixing and using 2 or more types of solvents as a solvent for positive hole injection layers, it is made for the sum total of these solvents to satisfy | fill this range.

After the application / film formation of the composition for hole injection layer, the obtained coating film is dried, and the hole injection layer 3 is formed by removing the solvent for hole injection layer.
The thickness of the hole injection layer 3 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

2-4. Light-Emitting Layer A light-emitting layer 5 is provided on the hole injection layer 3. The light emitting layer 5 is excited by recombination of holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 9 through the electron injection layer 8 between the electrodes to which an electric field is applied. , Which is the main light-emitting layer.

(Light emitting layer material)
The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transport. A compound (electron transporting compound) having the following properties: (Hereinafter, the hole transporting compound and the electron transporting compound may be collectively referred to as a “charge transporting compound”.) The light emitting substance is not particularly limited, and emits light at a desired light emitting wavelength, and has a light emitting efficiency. A substance that is good may be used. Moreover, it is preferable to contain two or more charge transport compounds. Furthermore, the light emitting layer 5 may contain other components as long as the effects of the present invention are not significantly impaired.

  Note that the light emitting material and the charge transporting compound contained in the light emitting layer are preferably low molecular compounds. These low molecular weight compounds are preferable from the viewpoints of high luminous efficiency and long drive life, high degree of freedom in material design, and wide choice of materials. However, since the molecule is small, it is easy to move in the layer, and generally it is a multi-component system. Therefore, each component is likely to aggregate in the layer, and it is considered more difficult to maintain the flatness of the layer surface. Therefore, the effect of the present invention appears more remarkably. In the present invention, the low molecular weight compound means a compound having a weight average molecular weight of usually 6000 or less, preferably 5000 or less, more preferably 1500 or less.

(Luminescent material)
Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.
For the purpose of improving the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecules of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.

Hereinafter, although the example of a fluorescent dye is mentioned among light emitting materials, a fluorescent dye is not limited to the following illustrations.
Examples of the fluorescent dye that gives blue light emission (blue fluorescent dye) include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

Examples of fluorescent dyes that give green light emission (green fluorescent dyes) include quinacridone derivatives and coumarin derivatives.
Examples of fluorescent dyes that give yellow light (yellow fluorescent dyes) include rubrene and perimidone derivatives.
Examples of fluorescent dyes that give red luminescence (red fluorescent dyes) include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzoates. Examples thereof include thioxanthene derivatives and azabenzothioxanthene.

Next, phosphorescent materials among the light emitting materials will be described. Examples of the phosphorescent material include an organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table.
Preferred examples of the metal selected from Groups 7 to 11 of the periodic table contained in the phosphorescent organometallic complex include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. . Preferred examples of these organometallic complexes include compounds represented by the following formula (V) or formula (VI).

{In Formula (V), M represents a metal, and q represents the valence of the metal. L and L ′ each represents a bidentate ligand. j represents a number of 0, 1 or 2. }

{In Formula (VI), M ⁷ represents a metal, and T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. }
Hereinafter, the compound represented by the formula (V) will be described first.
In formula (V), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.

  In the formula (V), the bidentate ligand L represents a ligand having the following partial structure.

In the partial structure of L, ring A1 ″ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.
Examples of the aromatic hydrocarbon group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene. And a monovalent group derived from a ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

Examples of the aromatic heterocyclic group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, and a benzoic ring. Thiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring , Benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring , Perimidine ring, key Gelsolin ring, quinazolinone ring, and a monovalent group derived from azulene ring.
In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  Examples of the nitrogen-containing aromatic heterocyclic group constituting the ring A2 include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole. Ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, And monovalent group derived from a quinazolinone ring.

Examples of the substituent that each ring A1 ″ or ring A2 may have include: a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a methoxycarbonyl group and an ethoxy group Alkoxycarbonyl groups such as carbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups Carbazolyl group; acyl group such as acetyl group; haloalkyl group such as trifluoromethyl group; cyano group; aromatic hydrocarbon group such as phenyl group, naphthyl group, phenanthyl group and the like.

In addition, as for the said substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.
In formula (V), bidentate ligand L ′ represents a ligand having at least one of the following partial structures. In the following formulae, “Ph” represents a phenyl group.

  Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

  More preferred examples of the compound represented by the formula (V) include compounds represented by at least one of the following formulas (Va), (Vb) and (Vc).

{In Formula (Va), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.}

{In Formula (Vb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent or Represents an aromatic heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.}

{In Formula (Vc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, ring A1 "and ring A1 'represent Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing optionally substituted group. Represents an aromatic heterocyclic group.}
In the above formulas (Va), (Vb) and (Vc), preferred examples of the ring A1 ″ and the ring A1 ′ include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzothienyl group, A benzofuryl group, a pyridyl group, a quinolyl group, an isoquinolyl group, a carbazolyl group, and the like can be given.

In the above formulas (Va), (Vb) and (Vc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, and benzimidazole group. Quinolyl group, isoquinolyl group, quinoxalyl group, phenanthridyl group and the like.
Examples of the substituent that the compound represented by any one of the formulas (Va), (Vb), and (Vc) may have include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group Alkenyl groups such as vinyl groups; alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dimethylamino groups and diethylamino groups A diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group and the like.

  The carbon number of the substituent is arbitrary as long as the effects of the present invention are not significantly impaired. However, when the substituent is an alkyl group, the carbon number is usually 1 or more and 6 or less. When the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less. When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less. Moreover, when a substituent is an alkoxy group, the carbon number is 1 or more and 6 or less normally. Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally. Moreover, when a substituent is a dialkylamino group, the carbon number is 2 or more and 24 or less normally. Moreover, when a substituent is a diarylamino group, the carbon number is 12 or more and 28 or less normally. When the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less. Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

The above substituents may be linked to each other to form a ring. As a specific example, ring A1 "
Or a substituent of ring A2 is bonded, or a substituent of ring A1 ′ and a substituent of ring A2 ′ are bonded to form one condensed ring. Also good. Examples of such a condensed ring include a 7,8-benzoquinoline group.
Among the substituents described above, the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′ are more preferably alkyl groups, alkoxy groups, aromatic hydrocarbon groups, cyano groups, halogen atoms, haloalkyl groups. , Diarylamino group, and carbazolyl group. In addition, as for the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′, only one may be substituted or two or more may be in any combination. And may be substituted with a ratio.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (Va), (Vb), and (Vc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.
Specific examples of the organometallic complex represented by any one of the above formulas (V), (Va), (Vb) and (Vc) are shown below. However, it is not limited to the following compounds.

Further, among the organometallic complexes represented by the above formula (V), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand (that is, 2-arylpyridine, an arbitrary substituent group) And a compound having an arbitrary group condensed thereto) are preferable.
The compounds described in International Publication No. 2005/019373 pamphlet can also be used as the light emitting material.

Next, the compound represented by formula (VI) will be described.
In the formula (VI), M ⁷ represents a metal. Specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the formula (VI), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, It represents at least one selected from the group consisting of an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. Each R ⁹² and R ⁹³ may be the same or different.

Further, when T is a carbon atom in the formula (VI), R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, in the formula (VI), when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. Each T may be the same or different.
In the formula (VI), R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent. Moreover, as for the substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.

Furthermore, in the formula (VI), any two or more groups out of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.
Specific examples (T-1 to T-7) of the organometallic complex represented by the formula (VI) are shown below. However, it is not limited to the following examples. In the following chemical formulae, Me represents a methyl group, and Et represents an ethyl group.

  The molecular weight of the compound used as the light emitting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, Preferably it is 200 or more, More preferably, it is 300 or more, More preferably, it is the range of 400 or more. If the molecular weight is too small, the heat resistance is remarkably reduced, gas generation is caused, the quality of the layer is lowered when the layer is formed, or the morphology of the organic EL element is changed due to migration or the like. Sometimes. On the other hand, if the molecular weight is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

In addition, any 1 type may be used for the luminescent material mentioned above, and 2 or more types may be used together by arbitrary combinations and a ratio.
The ratio of the light emitting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more, preferably 0.3% by weight or more, more preferably 0.5% by weight or more. In addition, it is usually 35% by weight or less, preferably 25% by weight or less, and more preferably 20% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range.

(Hole transporting compound)
Further, the light emitting layer 5 may contain a hole transporting compound as a constituent material. Here, among the hole transporting compounds, examples of the low molecular weight hole transporting compound include, in addition to the various compounds exemplified in the above-mentioned column of (Low molecular weight hole transporting compound), for example, 4 , 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl, which includes two or more tertiary amines and two or more condensed aromatic rings substituted with nitrogen atoms Aromatic amine compounds having a starburst structure such as diamine (Japanese Patent Laid-Open No. 5-234811), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), aromatic amine compounds consisting of tetramers of triphenylamine (Chemical Communications, 19). 6 years, pp. 2175), spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene (Synthetic Metals, 1997, Vol. 91, pp. 9 209) etc. In addition, in the light emitting layer 5, only 1 type may be used for a positive hole transport compound, and it may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the hole transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight. In addition, it is usually 99% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of hole transportable compounds, it is made for the total content of these to be contained in the said range.

(Electron transporting compound)
The light emitting layer 5 may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 -Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9-carbazole) -biphenyl (CBP), etc. In the light emitting layer 5, only one type of electron transporting compound may be used, or two or more types may be combined arbitrarily. It may be used in combination with not proportion.

  The ratio of the electron transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more. In addition, it is usually 99% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less. If the amount of the electron transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport compounds, it is made for the total content of these to be contained in the said range.

(Formation of light emitting layer)
The film forming method of the light emitting layer 5 is not particularly limited as described in “1. Light emitting layer forming / processing method”, and can be arbitrarily selected and employed such as a vacuum deposition method and a wet film forming method. In the case of wet film formation, even if each component is evenly dispersed in the composition, the portion slightly different in the composition ratio in the microscopic region causes the aggregation during storage. there is a possibility. Therefore, when the wet film forming method is adopted, the effect of the present invention is more remarkable.
Hereinafter, although the case of the wet film forming method will be described as an example, the film forming method is not limited to this.

  When the light emitting layer 5 is formed by a wet film forming method, the above-described various materials are dissolved in an appropriate solvent to prepare a coating composition, and the film is formed using the composition. In addition, as described in “1. Method for forming and treating light emitting layer”, the formed light emitting layer is subjected to a heat treatment after 6 hours or more, and another layer is laminated.

As the light emitting layer solvent to be contained in the coating composition for forming the light emitting layer 5, any solvent can be used as long as the light emitting layer 5 can be formed. However, those capable of dissolving the light-emitting material, the hole transporting compound, and the electron transporting compound described above are preferable. Specifically, the solubility of the light emitting material, the hole transporting compound, or the electron transporting compound is usually 0.01% by weight or more, particularly 0.05% by weight or more, and particularly preferably 0.00% at room temperature and normal pressure. It is preferable to dissolve 1% by weight or more.
Suitable examples of the solvent for the light emitting layer are the same as those described in “1. Method for forming and treating light emitting layer”.

  The ratio of the solvent for the light emitting layer to the coating composition for producing the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.1% by weight. Above, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. In addition, when mixing and using 2 or more types of solvents as a solvent for light emitting layers, it is made for the sum total of these solvents to satisfy | fill this range.

After the coating composition for producing the light emitting layer 5 is applied and formed, the obtained coating film is dried and the light emitting layer solvent is removed to form the light emitting layer 5. The method of the wet film forming method is not limited as long as the effects of the present invention are not significantly impaired, and any method described in the section of “1. Light emitting layer forming / processing method” can be used.
The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, defects may occur in the light emitting layer, and if it is too thick, the driving voltage of the organic EL element may increase.
In the present invention, after the light emitting layer 5 is formed in this manner and after 6 hours or more has passed, a heat treatment step is performed as described in the section of “1. Another layer such as a transport layer is laminated to produce an organic electroluminescent element.

2-5. Electron Transport Layer An electron transport layer 7 can be formed on the light emitting layer 5. The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

As an electron transporting compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility are efficiently transported. The compound which can be used is used. As a compound satisfying such conditions, for example, 8
-Metal complexes such as aluminum complexes of hydroxyquinoline (JP 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavones Metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds (JP-A-6-207169), phenanthroline derivatives (special No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, etc. Can be mentioned. In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of the electron carrying layer 7, It can form by well-known methods, such as a vacuum evaporation method.
The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

2-6. Electron Injection Layer The electron injection layer 8 serves to efficiently inject electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The film thickness is usually preferably from 0.1 nm to 5 nm.

Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.
In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron injection layer 8, It can form by well-known methods, such as a vacuum evaporation method.

2-7. Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side.
As the material of the cathode 9, the material used for the anode 2 can be used. However, a metal having a low work function is preferable for efficient electron injection. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy. In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The film thickness of the cathode 9 is usually the same as that of the anode 2.

Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

2-8. Other Layers The organic EL element having the layer configuration shown in FIG. 1 has been described above. However, the organic EL element according to the present invention may have another configuration without departing from the gist thereof. . For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

FIG. 2 is a cross-sectional view schematically showing another example of the structure of the organic EL element of the present invention. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.
The organic EL element 10b shown in FIG. 2 has a hole blocking layer 6 between the light emitting layer 5 and the electron transport layer 7 in addition to the same configuration as the organic EL element 10a of FIG. A hole transport layer 4 is provided between the hole injection layer 3 and the light emitting layer 5.

(2-8-1) Hole Transport Layer The material for forming the hole transport layer 4 is the same as the compound exemplified as the hole transport compound that may be used by mixing with the hole injection layer 3. Can be mentioned. In addition, for example, polymer materials such as polyarylene ether sulfone containing polyvinyl carbazole, polyvinyl triphenylamine, and tetraphenylbenzidine can be used. In addition, the material of the positive hole transport layer 4 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of the positive hole transport layer 4, It can form by well-known methods, such as a vacuum evaporation method and a wet film-forming method.
The film thickness of the hole transport layer 4 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10 nm or more, preferably 30 nm or more, and usually 300 nm or less, preferably 100 nm or less.

(2-8-2) Hole blocking layer The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side. The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have

The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. As a material for the hole blocking layer satisfying such conditions, for example, bis (2-methyl-8-quinolinolato), (phenolato) aluminum, bis (2-methyl-8-quinolinolato), (triphenylsilanolato) Mixed ligand complexes such as aluminum, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives Styryl compounds such as JP-A-11-242996 and triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole Kaihei 7-41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297). It is. Further, a compound having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 is also preferable as the material for the hole blocking layer 6. In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of the hole-blocking layer 6, It can form by well-known methods, such as a vacuum evaporation method.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

(2-8-3) Electron blocking layer An electron blocking layer is provided between the hole injection layer 3 (the hole transport layer 4 when the hole transport layer 4 is formed) and the light emitting layer 5. Also good. The electron blocking layer was generated by increasing the recombination probability of holes and electrons in the light emitting layer 5 by blocking electrons moving from the light emitting layer 5 from reaching the hole injection layer 3 side. There are a role of confining excitons in the light emitting layer 5 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 5. In particular, it is effective when a phosphorescent material or a blue light emitting material is used as the light emitting material.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Furthermore, in the present invention, when the light emitting layer 5 is formed as an organic layer according to the present invention by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (described in International Publication No. 2004/084260). In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of an electron blocking layer, It can form by well-known methods, such as a vacuum evaporation method and a wet film-forming method.

(2-8-4) at the interface of the other cathode 9 and the luminescent layer 5 or electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF2), lithium oxide _(Li 2 O), cesium carbonate ( II) Inserting an ultrathin insulating film (0.1 to 5 nm) formed of (CsCO ₃ ) or the like is also an effective method for improving the efficiency of the device (Applied Physics Letters, 1997, Vol. 70). , Pp.152; JP-A-10-74586;
Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154 etc.).

Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the layer configuration of FIG. 1, the cathode 9, the electron injection layer 8, the electron transport layer 7, the light emitting layer 5, the hole injection layer 3, and the anode 2 are provided on the substrate 1 in this order.
Furthermore, the organic EL element of the present invention can be configured by laminating components other than the substrate between two substrates, at least one of which is transparent.

In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (in the case where the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic EL element of the present invention may be configured as a single organic EL element, or may be applied to a configuration in which a plurality of organic EL elements are arranged in an array, and the anode and cathode are X- You may apply to the structure arrange | positioned at Y matrix form.
Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

3. Organic EL Display Device The organic EL display device of the present invention uses the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the model and structure of the organic electroluminescent display apparatus of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.
For example, the organic EL display device of the present invention can be obtained by the method described in “Organic EL display” (Ohm, published on Aug. 20, 2004, Shizushi Tokito, Chiba Adachi, Hideyuki Murata). Can be formed.

4). Organic EL lighting The organic EL lighting of the present invention uses the organic electroluminescent element of the present invention described above. There is no restriction | limiting in particular about the model and structure of the organic EL illumination of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of these examples without departing from the gist thereof.
[Example 1]
An organic electroluminescent device having the structure shown in FIG. 2 was prepared by the following method.

<Anode 2>
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 70 nm on a glass substrate 1 (sputtered film product) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching. Thus, an anode 2 was formed. The substrate on which the anode 2 is formed is cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, and then dried with nitrogen blow. UV ozone cleaning was performed.

<Hole injection layer 3>
Next, a composition for forming a hole injection layer was prepared. 2% by weight of polymer (HI-1) (weight average molecular weight 60000) having the following repeating structure and 0.4% by weight of an electron-accepting compound represented by the following formula (A1) were dissolved in ethyl benzoate as a solvent. A composition for forming a hole injection layer having a solid content concentration of 2.4% by weight was obtained.

  On the board | substrate in which the said anode 2 was formed, it formed into a film by the spin coat method using the said composition for hole injection layer formation. Spin coating was performed in an air atmosphere at a temperature of 23 ° C. and a relative humidity of 50%, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After film formation, the film was dried on a hot plate at 80 ° C. for 1 minute, and then baked in an oven atmosphere at 230 ° C. for 1 hour to crosslink the polymer to form a hole injection layer 3 having a thickness of 30 nm.

<Hole transport layer 4>
Next, a composition for forming a hole transport layer was prepared. A polymer (HT-1) (weight average molecular weight 95000) having the following repeating structure (1.4% by weight) was dissolved in cyclohexylbenzene as a solvent to obtain a composition for forming a hole transport layer. Cyclohexylbenzene was obtained by adding a molecular sieve to a commercial product and dehydrated. The composition for forming a hole transport layer was prepared in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.

  The substrate on which the hole injection layer 3 was formed was put in a nitrogen glove box, and a film was formed on the hole injection layer 3 by the spin coating method using the composition for forming a hole transport layer. The spinner speed was 1500 rpm and the spinner time was 120 seconds. After film formation, the polymer was crosslinked by baking at 230 ° C. for 1 hour on a hot plate to form a hole transport layer 4 having a thickness of 15 nm.

<Light emitting layer 5>
Next, a composition for forming a light emitting layer was prepared. The following compound (BH-1) 1.1% by weight and compound (BD-1) 0.1% by weight were dissolved in xylene as a solvent to obtain a composition for forming a light emitting layer. As the xylene, a commercially available dehydrated grade was used, and the light emitting layer forming composition was prepared in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.

  On the said positive hole transport layer 4, it formed into a film by the spin coat method using the said composition for light emitting layer formation. The spinner speed was 1500 rpm and the spinner time was 50 seconds. After the film formation, it was baked on a hot plate at 130 ° C. for 60 minutes and dried to form a light emitting layer 5 having a thickness of 40 nm.

(Storage of light emitting layer forming substrate)
The substrate on which the light emitting layer 5 was formed was stored for 18 hours in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.
(Bake the light emitting layer-formed substrate after storage (heat treatment process))
The substrate after the storage was heated at 130 ° C. for 30 minutes on a hot plate in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.

Thereafter, the substrate was placed in a chamber of a vacuum deposition apparatus without being exposed to the atmosphere. The degree of vacuum in the chamber was 1.0 × 10 ⁻⁵ Pa. A vapor deposition mask was disposed in a predetermined area on the substrate, and necessary vapor deposition materials were previously placed in separate molybdenum boats in the chamber.

<Hole blocking layer 6>
Next, the light-emitting layer 5 is formed, and after storage, a molybdenum boat containing a compound represented by the following structural formula is deposited on the heat-treated substrate by heating to form a hole blocking layer 6. did. The deposition conditions were such that the degree of vacuum during deposition was 1.0 × 10 ⁻⁵ Pa, the deposition rate was 1.0 Å / s, and the hole blocking layer 6 was formed with a thickness of 10 nm.

<Electron transport layer 7>
Next, a molybdenum boat containing a compound (Alq ₃ ) represented by the following structural formula was heated by current application and evaporated on the hole blocking layer 6 to form an electron transport layer 7. The deposition conditions were such that the degree of vacuum during deposition was 1.0 × 10 ⁻⁵ Pa, the deposition rate was 1.0 Å / s, and the electron transport layer 7 was formed to a thickness of 20 nm.

<Electron injection layer 8>
Next, the substrate laminated up to the hole blocking layer 7 is placed in another vacuum chamber without being exposed to the atmosphere, and a 2 mm wide striped shadow mask is used as a cathode 9 deposition mask. They were arranged so as to be orthogonal. The degree of vacuum in the chamber is 1 × 10 ⁻⁵ Pa
Met. A molybdenum boat containing lithium fluoride (LiF) was energized and heated and deposited on the electron transport layer 7 to form an electron injection layer 8. The deposition conditions were such that the degree of vacuum during deposition was 1.0 × 10 ⁻⁵ Pa, the deposition rate was 0.1 Å / s, and the electron injection layer 8 was formed with a thickness of 0.5 nm.
<Cathode 9>
Next, a molybdenum boat containing aluminum was energized and heated to deposit the cathode 9. The deposition conditions were such that the degree of vacuum during deposition was 3.0 × 10 ⁻⁵ Pa, the deposition rate was 5.0 Å / s, and the cathode 9 was formed with a film thickness of 80 nm.

<Sealing>
The substrate provided up to the cathode was transferred to a glove box substituted with nitrogen without being exposed to the atmosphere. In a glove box substituted with nitrogen, a hygroscopic sheet is attached to the concave portion of the sealing glass plate, and a UV curable resin coating is applied around the concave portion of the sealing glass plate with a dispenser. The parts were brought into close contact with a sealing glass plate, and UV light was irradiated with a UV lamp to cure the UV curable resin.
As described above, an organic electroluminescent element was produced.

[Element evaluation]
The obtained element was continuously energized to 48 mA / cm ² , the luminance change was measured with a photodiode, and the time was measured until it deteriorated to 70% of the initial luminance. The results are shown in Table-1.
[Light emitting layer surface check]
The surface roughness of the light emitting layer 5 before forming the hole blocking layer 6 was measured by VertScan (manufactured by Ryoka Systems Inc.). The results are shown in Table-2 and Table-3. In addition, the evaluation result in Table-2 and Table-3 is an average value of the result of having measured three places within the same surface. The measurement area was 250 μm × 188 μm.
In the table, Sa and Sb are indices representing the surface roughness, Sa represents the arithmetic average roughness, and St represents the maximum cross-sectional height roughness. Each of the surface roughnesses Ra and Rt described in JIS B0601: 2001 is applied to the three-dimensional measurement surface.

[Comparative Example 1]
An organic electroluminescent element was produced in the same manner as in Example 1 except that (storage of the light emitting layer forming substrate) and (baking of the light emitting layer forming substrate after storage (heat treatment step)) were not performed.
[Comparative Example 2]
An organic electroluminescent element was produced in the same manner as in Example 1 except that (the baking of the light emitting layer-formed substrate after storage (heat treatment step)) was not performed.

[Example 2]
An organic electroluminescent element was produced in the same manner as in Example 1 except that (storage of the light emitting layer forming substrate) and (baking of the light emitting layer forming substrate after storage (heat treatment step)) were changed as follows. The surface of the light emitting layer was confirmed. The results are shown in Table-3.
(Storage of light emitting layer forming substrate)
The substrate on which the light emitting layer 5 was formed was stored for 7 days in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.
(Baking of light-emitting layer-formed substrate after storage (heat treatment process))
The substrate after the storage was heated at 130 ° C. for 30 minutes on a hot plate in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.
[Example 3]
An organic electroluminescent element was produced in the same manner as in Example 2 except that (baking of the light emitting layer-formed substrate after storage (heat treatment step)) was changed as follows, and the surface of the light emitting layer was confirmed. The results are shown in Table-3.
(Baking of light-emitting layer-formed substrate after storage (heat treatment process))
The substrate after the storage was heated at 130 ° C. for 3 hours on a hot plate in a nitrogen glove box having an oxygen concentration of 1.0 ppm and a water concentration of 1.0 ppm.
[Comparative Example 3]
An organic electroluminescent element was produced in the same manner as in Example 2 except that the baking of the light emitting layer forming substrate after storage (heat treatment step) was not performed, and the surface of the light emitting layer was confirmed. The results are shown in Table-3.

According to the present invention, in the manufacturing process of the organic electroluminescent element, even when a certain time or more has elapsed from the formation of the light emitting layer to the formation of the upper layer, the performance of the obtained element is not reduced, A high-performance organic electroluminescence device can be stably produced. As a result, the process margin is widened, which is very useful in the industrial production of organic electroluminescent devices.
The organic electroluminescent device obtained by the production method of the present invention is, for example, a flat panel display (for example, for OA computers or wall-mounted televisions) or a light source utilizing characteristics as a surface light emitter (for example, a light source of a copying machine, a liquid crystal (Backlight light source for displays and instruments), display boards, indicator lamps, lighting equipment, etc., can be suitably used.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode

Claims (8)

A method for producing an organic electroluminescent device comprising a first electrode, a light emitting layer, and a second electrode in this order,
A method for producing an organic electroluminescent element, comprising: heating the light emitting layer after 6 hours or more has elapsed after forming the light emitting layer, and then forming a layer corresponding to an upper layer of the light emitting layer.   The manufacturing method of the organic electroluminescent element of Claim 1 which forms the said light emitting layer with a wet film-forming method.   The manufacturing method of the organic electroluminescent element of Claim 1 or 2 in which the said light emitting layer contains the luminescent material which is a low molecular compound, and the charge transportable compound which is a low molecular compound.   4. The method of manufacturing an organic electroluminescent element according to claim 1, wherein at least one charge transport layer is formed between the first electrode and the light emitting layer by a wet film forming method. 5.   The heating temperature in the heat treatment step is (Tg-30) ° C or higher and (Tg + 50) ° C or lower with respect to Tg of the compound having the lowest glass transition point (Tg) among the materials constituting the light emitting layer. The manufacturing method of the organic electroluminescent element as described in any one of 1 thru | or 4.   The organic electroluminescent element obtained by the manufacturing method as described in any one of Claims 1 thru | or 5.   Organic EL illumination provided with the organic electroluminescent element of Claim 6.   An organic EL display device comprising the organic electroluminescent element according to claim 6.

Images