JP2006278068A - Method for manufacturing organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an organic electroluminescent element excellent in durability without attenuating emission luminance even by long-term drive, and to provide an organic electroluminescent element obtained by the manufacturing method. <P>SOLUTION: In the method for manufacturing the organic electroluminescent element wherein layers are deposited by vapor deposition, in at least one layer of a charge injection layer, a charge transport layer, and the light emitting layer which are included in the organic compound layer, the method comprises a cleaning step for decreasing the content of aromatic hydrocarbon, alicyclic hydrocarbon, and aliphatic hydrocarbon, wherein the optical band gap (Eg) is 400 nm or less, or the content of aromatic hydrocarbon, alicyclic hydrocarbon, and aliphatic hydrocarbon wherein the molecular weight is 300-750 to less than 5 mass% per one layer, and a deposition step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an organic electroluminescent element, and an organic electroluminescent element obtained by the production method (hereinafter sometimes referred to as “organic EL element” as appropriate).

In an organic EL element, it is known that the purity of various organic compounds used as a constituent material of the element strongly influences light emission efficiency and light emission luminance degradation.
For example, the following Non-Patent Document 1 and Non-Patent Document 2 have a description that the purity of various organic compounds used as a constituent material of the organic EL element strongly affects the light emission efficiency and the attenuation of the light emission luminance.
Furthermore, as a practical problem in the organic EL element, it is possible to establish a technique that can suppress the attenuation of the light emission luminance of the organic EL element due to long-term driving and can withstand practical use.
However, the details of the effects of the structures and properties of various organic compounds used in organic EL devices on the performance of organic EL devices are not yet clear, and a method for quantitatively elucidating them has been established. Not in. Actually, the luminance degradation is greatly influenced by the film forming conditions, and the variation in luminance degradation itself is extremely large, and the secondary cause as well as the main cause is often unclear.
Under the above circumstances, an organic EL element that can be applied to a lightweight, thin, low-voltage drive display, has little deterioration in light emission luminance due to long-term driving, and has excellent driving durability, and The manufacturing method for obtaining such an organic EL element has not yet been provided.
Monthly display, September issue, 15 pages (1995) Applied Physics, Vol. 66, No. 2, 114-115 (1997)

  An object of the present invention is to provide a method for producing an organic electroluminescent device having a small attenuation of light emission luminance due to long-term driving and excellent durability, and an organic electroluminescent device obtained by the production method. .

  As a result of various studies to solve the above problems, the inventor of the present invention, in an organic compound layer (at least one of a charge injection layer, a charge transport layer, and an organic light emitting layer) formed by vapor deposition, The inventors have found that the object can be achieved by reducing the content of the specific hydrocarbon contained in the present invention, and have completed the present invention.

That is, the means for solving the problems of the present invention are as follows.
(1) A method for producing an organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition.
Aromatic hydrocarbons and alicyclic hydrocarbons having an optical band gap (Eg) of 400 nm or less in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer among the layers included in the organic compound layer. And a cleaning step for reducing the content of aliphatic hydrocarbons to less than 5% by mass per layer;
A method for producing an organic electroluminescent element, comprising: a vapor deposition step.
(2) A method for producing an organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer, the molecular weight is 300 to 750, the aromatic hydrocarbon, the alicyclic hydrocarbon, and the aliphatic A cleaning step for reducing the hydrocarbon content to less than 5% by weight per layer;
A method for producing an organic electroluminescent element, comprising: a vapor deposition step.

(3) The method for producing an organic electroluminescent element according to (1) or (2), wherein the organic light emitting layer contains at least one phosphorescent material.
(4) The method for producing an organic electroluminescent element as described in (3), wherein a peak emission wavelength of the phosphorescent material contained in the organic light emitting layer is 550 nm or less.
(5) The method for producing an organic electroluminescent element according to (3), wherein the peak emission wavelength of the phosphorescent material contained in the organic light emitting layer is 500 nm or less.

(6) An organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer has an optical band gap (Eg) of 400 nm or less, an aromatic hydrocarbon, an alicyclic carbonization An organic electroluminescent element, wherein the content of hydrogen and aliphatic hydrocarbon is less than 5% by mass per layer.

(7) An organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer, the molecular weight is 300 to 750, the aromatic hydrocarbon, the alicyclic hydrocarbon, and the fat An organic electroluminescent element, wherein the content of the group hydrocarbon is less than 5% by mass per layer.

(8) The organic electroluminescent element as described in (7) or (8), wherein the organic light emitting layer contains at least one phosphorescent material.
(9) The organic electroluminescent element as described in (8), wherein the peak emission wavelength of the phosphorescent material contained in the organic light emitting layer is 550 nm or less.
(10) The organic electroluminescent element as described in (8), wherein the peak emission wavelength of the phosphorescent material contained in the organic light emitting layer is 500 nm or less.

  According to the present invention, it is possible to provide a method for manufacturing an organic electroluminescent device having a small attenuation of light emission luminance due to long-term driving and excellent durability, and an organic electroluminescent device obtained by the manufacturing method. .

  Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Method of manufacturing organic electroluminescent element]
The method for producing an organic electroluminescent element of the present invention has an organic compound layer including at least an organic luminescent layer between a pair of electrodes, and the organic electroluminescent element is formed by vapor deposition. An aromatic hydrocarbon or an oil having an optical band gap (Eg) of 400 nm or less in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer among the layers included in the organic compound layer. A cleaning step for reducing the content of the cyclic hydrocarbon and the aliphatic hydrocarbon to less than 5% by mass per layer, and a vapor deposition step (hereinafter referred to as “production method” as appropriate). 1) ").

In another aspect of the method for producing an organic electroluminescent element of the present invention, an organic compound layer including at least an organic light emitting layer is provided between a pair of electrodes, and the organic compound layer is formed by an evaporation method. A method for producing an electroluminescent device, wherein among the layers included in the organic compound layer, an aromatic hydrocarbon having a molecular weight of 300 to 750 in at least one of a charge injection layer, a charge transport layer, and an organic light emitting layer, A cleaning step for reducing the content of the alicyclic hydrocarbon and the aliphatic hydrocarbon to less than 5% by mass per layer, and a vapor deposition step (hereinafter referred to as “production method” as appropriate). (2) ").
In the following description, the cleaning process in the manufacturing methods (1) and (2) may be simply referred to as “cleaning process”.
Further, “an aromatic hydrocarbon, an alicyclic hydrocarbon, and an aliphatic hydrocarbon having an optical band gap (Eg) of 400 nm or less”, or “an aromatic hydrocarbon having a molecular weight of 300 to 750, The “alicyclic hydrocarbon and aliphatic hydrocarbon” may be simply referred to as “specific hydrocarbon”.

Manufacturing methods (1) and (2) are methods for forming an organic compound layer by vapor deposition, and include at least a cleaning step and a vapor deposition step.
Here, the vapor deposition method is generally a vacuum in which a substance is heated and evaporated under high vacuum (10 ⁻² Pa or less), and a gaseous substance is deposited on a target (substrate). Although it means a vapor deposition method, the vapor deposition method referred to in this specification includes all vapor deposition techniques in a broader sense. For example, a CVD method for forming a film by a chemical reaction on the target surface is also included in the vapor deposition method of the present invention.
Details of the vapor deposition method are described in Chapter 8 of "New Edition / Vacuum Handbook" (edited by ULVAC, Inc.) published by Ohm.

  In the production methods (1) and (2) of the present invention, when the organic compound layer is formed by the evaporation method as described above, among the layers contained in the organic compound layer, the charge injection layer, the charge transport layer, the organic Focusing on the presence of specific hydrocarbons that can be mixed as impurities in at least one layer of the light-emitting layer, and including a cleaning process for reducing such specific hydrocarbons, the emission luminance associated with long-term driving An organic EL element having a small attenuation and excellent durability can be manufactured.

-Cleaning process-
The cleaning process in the present invention is a process for cleaning the inside of the chamber in which the vapor deposition process is performed, and is performed prior to the vapor deposition process. The vapor deposition process will be described in detail later.

  As an aspect of cleaning in this step, the specific hydrocarbon can be decomposed and removed into carbon dioxide and steam by an oxidizing power using oxygen.

In cleaning by plasma discharge, a cleaning gas (oxygen, silicon tetrafluoride, etc.) is introduced into a vacuum vessel, and plasma is generated by applying high frequency power or direct current power to an electrode provided in the vacuum vessel. The gas is decomposed by a chemical reaction with plasma energy, and the deposits on the wall of the vacuum reaction vessel are removed by etching mainly due to the reactivity of the chemically active species of the decomposed radicals. As an example, Ar 1000 ml / min, O ₂ 1000 ml / mim, 25 ° C., vacuum degree 300 Pa, and high-frequency power 300 W can be used.

In the cleaning process, the specific hydrocarbon to be removed (reduced) is “an aromatic hydrocarbon, an alicyclic hydrocarbon, and an aliphatic hydrocarbon having an optical band gap (Eg) of 400 nm or less”, or “Aromatic hydrocarbons, alicyclic hydrocarbons and aliphatic hydrocarbons having a molecular weight of 300 to 750”.
It is presumed that such specific hydrocarbons are mixed into the organic EL element through equipment or personnel involved in the production of the organic EL element, particularly due to back diffusion from the oil (oil) of the rotary pump. I guess that.
By performing the cleaning process, it is possible to decompose and remove not only the specific hydrocarbons but also organic substances as raw materials adhering in the chamber wall and impurities such as metallic sodium coming out of the chamber wall.

  The cleaning process is performed before the substrate that is the deposition target is carried into the chamber. Specifically, after filling the chamber with oxygen gas, plasma discharge is performed, and the chamber is cleaned with ozone generated thereby.

  The cleaning is more effective as the number of times increases until the number of times of saturation is reached.

As described above, the specific hydrocarbon in the present invention has an optical band gap (Eg) of 400 nm or less, or a molecular weight of 300 to 750, an aromatic hydrocarbon, an alicyclic hydrocarbon, and an aliphatic carbon. Hydrogen.
Such specific hydrocarbons include not only typical linear unsaturated hydrocarbons but also unsaturated hydrocarbons in addition to branched-chain hydrocarbons. Specific examples include saturated or unsaturated hydrocarbons such as n-nonacosane, n-dotriacontane, n-pentatriacontane, and dococene. In this case, the number of carbons in the hydrocarbon, the number of unsaturations, and the side chain are not significantly affected.

In the present invention, among the layers included in the organic compound layer, the content of the specific hydrocarbon is reduced to less than 5% by mass in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer. It is necessary to reduce it to less than 3% by mass.
In the present invention, if the specific hydrocarbon content in any one of the charge injection layer, the charge transport layer, and the organic light emitting layer is less than 5% by mass per layer, the effects of the present invention can be exhibited. However, the content of the specific hydrocarbon in all these layers is more preferably less than 5% by mass.
In addition, the organic EL device (organic EL device of the present invention) obtained by the production method of the present invention is required to include an organic light emitting layer in the organic compound layer, but for the charge injection layer and the charge transport layer, It can also be omitted. When the organic EL device of the present invention is an embodiment in which the organic compound layer does not include a charge injection layer and / or a charge transport layer, an organic light emitting layer, a charge injection layer present in the organic compound layer And / or the content of the specific hydrocarbon in any one of the charge transport layers may be less than 5% by mass per layer.

Among the specific hydrocarbons contained in the organic compound layer, as a method for measuring the content of “aromatic hydrocarbons, alicyclic hydrocarbons, and aliphatic hydrocarbons having a molecular weight of 300 to 750”, Examples of the method include FD-MS, TOF-SIMS, GC-MS, and high performance liquid chromatography. In this specification, high performance liquid chromatography is employed. Below, the measurement of the specific hydrocarbon which applied the high performance liquid chromatography method is demonstrated.
<Preparation of sample>
For example, when the organic compound layer is deposited by resistance heating, the sample is placed on a glass substrate for sample preparation in one of a plurality of patterns provided on the mask, and the organic compound layer deposited on the glass surface ( Organic material) can be obtained by taking it out and storing it in a clean container without sealing like an element.
<Quantitative measurement>
Next, the organic material adhering to the glass substrate was scraped off with a spatula to obtain a powdery sample, which was extracted with a solvent. This sample is quantitatively measured by high performance liquid chromatography.

In the measurement, the specific hydrocarbon has a molecular weight of 300 to 750. In actual measurement, many molecules having a molecular weight in the above range are detected, and the content of the specific hydrocarbon is calculated from the sum of the masses of the individual molecules.
After performing the above cleaning process, a vapor deposition process is performed.

-Vapor deposition process-
As described above, the vapor deposition process in the present invention is a vapor deposition method in which a vapor deposition material in a storage container is evaporated by heating or the like, and an organic EL element such as an organic compound layer is deposited on a deposition target such as a substrate. This refers to the step of forming the constituent layers.
The heating or the like is not particularly limited as long as it is a method for evaporating a vapor deposition material (organic material, etc.), and includes a heating method and a method other than heating. A method of heating is preferred.

  As a heating method for evaporating the vapor deposition material, there are a resistance heating method, a high frequency heating method, an electron beam heating method, a laser heating method, and the like, but the resistance heating method is preferable in terms of simplicity. These heating methods may be either indirect heating for heating the storage container or direct heating of the vapor deposition material, but indirect heating in which the storage container is heated is preferable.

  Moreover, as a method of evaporating the material by a method other than heating, there are a sputtering method, an ion plating method, a molecular beam epitaxy method, and the like, which can be properly used depending on the purpose.

  Although it depends on the vapor deposition material used, the heating temperature is generally 100 ° C to 1000 ° C, and preferably 100 ° C to 500 ° C.

  In the case of forming a film with a mixture of two or more substances, a mixture of a plurality of substances may be evaporated in one storage container. However, in this method, the composition of the substance in the evaporated gas is kept constant. Since it is difficult, it is common to fly molecules from different evaporation sources at the same time. The latter is also preferred in the present invention.

  The organic compound layer formed by vapor deposition does not contain impurities, oxygen, or moisture derived from solvents, binders, etc., compared to the case where wet film formation methods typified by spin coating and ink jet methods are applied. It is excellent in terms of luminance and driving durability, and a light emitting layer thin film having a desired film thickness can be easily obtained without worrying about dissolving an existing lower layer with a solvent.

  Further, by performing masking at the time of vapor deposition, different light emitting materials and host materials can be used for each pixel to have different light emitting characteristics, which is suitable for manufacturing a fine color display with high definition and high image quality.

Hereinafter, although an example of the vapor deposition process in the manufacturing method of the organic EL element of this invention is shown concretely, this invention is not limited to this.
The metal chamber of the vacuum evaporation machine is brought into a vacuum state by a rotary pump, and the vacuum is reduced to about 10 ⁻⁴ (Pa) to remove internal oxygen and moisture. After that, the crucible was heated by a plurality of crucibles and respective heating devices (resistance heating type) in a part of the inside (mostly in the lower part) to evaporate the organic material put in the crucible (in the upper part Often, organic materials are deposited on a substrate attached to a substrate holder. The crucible and the heating device are changed in order, and deposition with an organic material corresponding to the organic compound layer is repeated. Finally, after depositing the entire organic compound layer, the substrate on which the organic compound layer is formed is transported to another vacuum chamber, and a metal material is placed in the crucible, and the crucible is heated to deposit the metal. This is transported again from the vacuum chamber, the substrate on which the metal is deposited is transported to a separate room filled with nitrogen, and a thermoplastic resin is applied around the substrate to prevent oxygen and moisture from entering. Seal with.

[Organic electroluminescence device]
Hereinafter, the organic electroluminescent element (organic EL element) of the present invention will be described in detail.
The organic EL device of the present invention is an organic electroluminescent device having an organic compound layer including at least an organic light emitting layer between a pair of electrodes, and the organic compound layer is formed by vapor deposition. Among the layers included in the compound layer, at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer has an optical band gap (Eg) of 400 nm or less, an aromatic hydrocarbon, an alicyclic hydrocarbon, And the content of the aliphatic hydrocarbon is less than 5% by mass per layer.
Another aspect of the organic EL device of the present invention is an organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, and the organic compound layer is formed by vapor deposition. An aromatic hydrocarbon or an alicyclic hydrocarbon having a molecular weight of 300 to 750 in at least one of a charge injection layer, a charge transport layer, and an organic light emitting layer among the layers included in the organic compound layer. And the content of the aliphatic hydrocarbon is less than 5% by mass per layer.
The organic EL device of the present invention can be obtained by the production methods (1) and (2) of the present invention described above. Hereinafter, the details of the organic EL device of the present invention will be described.

  The organic EL device of the present invention has a cathode and an anode on a substrate, and an organic compound layer including an organic light emitting layer (hereinafter sometimes simply referred to as “light emitting layer”) between both electrodes. In view of the properties of the light-emitting element, at least one of the anode and the cathode is preferably transparent.

As the organic compound layer, in addition to the light emitting layer, a charge transport layer (hole transport layer, electron transport layer), a charge block layer (hole block layer, electron block layer), a charge injection layer (hole injection layer, electron injection) Layer), and the like.
In the present invention, among the layers contained in these organic compound layers, the content of the specific hydrocarbon in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer is less than 5% by mass per layer. It is characterized by being.
The details of the specific hydrocarbon and the content thereof are as described in the above-described method for producing an organic EL element of the present invention.

As a lamination mode of the organic compound layer, a mode in which a hole transport layer, a light emitting layer, and an electron transport layer are stacked in this order from the anode side is preferable. Further, a charge blocking layer or the like may be provided between the hole transport layer and the light-emitting layer, or between the light-emitting layer and the electron transport layer. A hole injection layer may be provided between the anode and the hole transport layer, and an electron injection layer may be provided between the cathode and the electron transport layer. Each layer may be divided into a plurality of secondary layers.
Next, the element which comprises the organic EL element of this invention is demonstrated in detail.

<Board>
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the organic compound layer. Specific examples thereof include zirconia stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Organic materials such as norbornene resin and poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

<Anode>
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. As described above, the anode is usually provided as a transparent anode.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc. Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  There is no restriction | limiting in particular as a formation position of an anode, According to the use and objective of an organic EL element, it can select suitably. Is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  The transparent anode is described in detail in the book “New Development of Transparent Electrode Films” published by CMC (1999), supervised by Yutaka Sawada, and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

<Cathode>
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, Examples thereof include magnesium-silver alloys, rare earth metals such as indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01 to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy, etc.) Say.

  The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these public relations can also be applied in the present invention.

  There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

There is no restriction | limiting in particular in the cathode formation position, You may form in the whole on an organic compound layer, and you may form in the one part.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

<Organic compound layer>
The organic compound layer in the present invention will be described.
The organic EL device of the present invention has at least one organic compound layer including a light emitting layer, and as the organic compound layer other than the organic light emitting layer, as described above, a hole transport layer, an electron transport layer, Examples include a charge blocking layer (hole blocking layer, electron blocking layer), a charge injection layer (hole injection layer, electron injection layer), and the like.

-Formation of organic compound layer-
In the organic EL device of the present invention, each layer constituting the organic compound layer is formed by a vapor deposition method.

-Light emitting layer-
The light-emitting layer receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer which has the function to provide and to emit light.

The light emitting layer may be composed of only the light emitting material, or may be a mixed layer of the host material and the light emitting material. The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, and may be one type or two or more types. The light emitting material in the present invention is preferably a phosphorescent light emitting material. The host material is preferably a charge transport material.
The host material may be one type or two or more types. As an aspect using 2 or more types of host materials, the aspect which mixed the host material of electron transport property and the host material of hole transport property is mentioned, for example. Furthermore, the light emitting layer may include a material that does not have charge transporting properties and does not emit light.
Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

  Examples of fluorescent materials that can be used in the present invention include, for example, benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives. , Condensed aromatic compounds, perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyralidine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, cyclopentadiene derivatives, styryl Of amine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidin compounds, metal complexes of 8-quinolinol derivatives and pyromethene derivatives And various metal complexes typified by metal complex, polythiophene, polyphenylene, polyphenylene vinylene polymer compounds include compounds such as organic silane derivatives.

  When the light emitting layer includes a fluorescent light emitting material as a light emitting material, it can be suitably used to form the light emitting layer only with the fluorescent light emitting material, or the host material can be mixed with the fluorescent light emitting material. Forming a light emitting layer can also be suitably used. The concentration of the fluorescent compound in the case of the mixed layer of the host material and the fluorescent material is preferably 0.1 to 99.9% by mass, and preferably 1 to 99% by mass, per one light emitting layer. It is more preferable that the content is 10 to 90% by mass.

  The phosphorescent material contained in the light emitting layer preferably has a peak emission wavelength of 550 nm or less, and more preferably 500 nm or less.

Examples of the phosphorescent material that can be preferably used in the present invention include complexes containing transition metal atoms or lanthanoid atoms.
Although it does not specifically limit as a transition metal atom, Preferably, ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum are mentioned, More preferably, they are rhenium, iridium, and platinum.
Examples of lanthanoid atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H. Yersin, “Photochemistry and Photophysics of Coordination Compounds,” Springer-Verlag, 1987, Akio Yamamoto. Examples of the ligands described in the book “Organic Metal Chemistry-Fundamentals and Applications-” published in 1982 by Hankabosha.
Specific ligands are preferably halogen ligands (preferably chlorine ligands), nitrogen-containing heterocyclic ligands (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline, etc.), diketones Ligand (for example, acetylacetone), carboxylic acid ligand (for example, acetic acid ligand), carbon monoxide ligand, isonitrile ligand, cyano ligand, more preferably nitrogen-containing Heterocyclic ligand. The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  The phosphorescent material is preferably contained in the light emitting layer in an amount of 0.1 to 40% by mass, and more preferably 0.5 to 20% by mass.

  Examples of the host material contained in the light emitting layer in the present invention include those having a carbazole skeleton, those having a diarylamine skeleton, those having a pyridine skeleton, those having a pyrazine skeleton, those having a triazine skeleton, and aryl. Examples thereof include materials having a silane skeleton and materials exemplified in the sections of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer described later.

  Although the thickness of a light emitting layer is not specifically limited, Usually, it is preferable that they are 1 nm-500 nm, it is more preferable that they are 5 nm-200 nm, and it is still more preferable that they are 10 nm-100 nm.

-Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. Specifically, the hole injection layer and the hole transport layer are carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamines. Derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, organosilane derivatives, carbon , Etc. are preferable.
The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and still more preferably 1 nm to 100 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

-Electron injection layer, electron transport layer-
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. Specifically, the electron injection layer and the electron transport layer are triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, Carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, aromatic tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, benzoxazoles and benzothiazoles as ligands It is preferably a layer containing various metal complexes typified by metal complexes, organosilane derivatives, and the like.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 50 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

-Hole blocking layer-
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the organic compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

<Protective layer>
In the present invention, the entire organic EL element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal nitrides such as SiNx and SiNxOy, metal fluorides such as MgF2, LiF, AlF ₃ and CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea Copolymerizing a monomer mixture comprising polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer The resulting copolymer, containing a cyclic structure in the copolymer main chain Examples thereof include an elemental copolymer, a water-absorbing substance having a water absorption of 1% or more, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited, and for example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

<Sealing>
Furthermore, the organic EL device of the present invention may be sealed using a sealing container.
Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide and the like. The inert liquid is not particularly limited, and examples thereof include fluorinated solvents such as paraffins, liquid paraffins, perfluoroalkanes, perfluoroamines, perfluoroethers, chlorinated solvents, and silicone oils. It is done.

The organic EL light-emitting device of the present invention emits light by applying a direct current (which may include an alternating current component if necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Obtainable.
The driving method of the organic electroluminescence device of the present invention is described in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234658, and JP-A-8-2441047. The driving methods described in each publication, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429, 6023308, and the like can be applied.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
[Example 1]
The following elements were produced as the organic EL elements of Example 1, and in the production of the elements, the cleaning process (chamber cleaning) by plasma discharge described above was performed a single time and the case where the cleaning process was performed a plurality of times. Evaluation was made on "impurity amount (specific hydrocarbon amount)" and "luminance half-life".

<Production of organic EL element>
A transparent electrode substrate was prepared by forming an ITO electrode with a thickness of 100 nm on a white glass substrate having a size of 25 mm × 25 mm × 0.7 mm. The substrate was ultrasonically cleaned with isopropyl alcohol for 30 minutes, then ultrasonically cleaned with ultrapure water for 30 minutes, and further ultrasonically cleaned with isopropyl alcohol for 30 minutes. This transparent electrode substrate is fixed to a substrate holder of a commercially available vapor deposition apparatus (made by Tokki), 50 mg of CuPC is put into a crucible, 50 mg of NPD is put into another crucible, and CBP and Ir (ppy) ₃ ( 40 mg and 2 mg of the mixture of the peak wavelength: 516 nm) were added, 80 mg of Balq ₂ was put in another crucible, and 80 mg of Alq was put in another crucible, and the vacuum layer was decompressed to 1 × 10 ⁻⁴ Pa.
Thereafter, the boat containing CuPC was heated to 300 to 315 ° C. and deposited on the transparent electrode substrate at a deposition rate of 0.3 to 0.6 nm / second to form a 10 nm thick hole injection layer. The substrate temperature at this time was room temperature. Without removing this from the vacuum layer, NPD is heated from 300 ° C. to 320 ° C. from another crucible on the hole injection layer, and a positive film thickness of 30 nm is obtained at a deposition rate of 0.3 to 0.6 nm / second. A hole transport layer was deposited.

On top of this, the crucible was heated to 290 ° C. to 310 ° C., and a mixed film of CBP and Ir (ppy) ₃ was deposited as a light emitting layer at a deposition rate of 0.3 to 0.6 nm / second. On top of this, the crucible was heated and heated to 300 ° C. to 320 ° C. using Balq ₂ as a hole blocking layer, and a film thickness of 10 nm was deposited at a deposition rate of 0.3 to 0.6 nm / second. Moreover, Alq was used as an electron carrying layer on that, the crucible was heated to 300 to 320 degreeC, and 40-nm-thickness vapor deposition was carried out at the vapor deposition rate of 0.3-0.6 nm / sec. The above was evaporated in vacuum without removing the film. The substrate temperature was room temperature.
Next, 1.1 g of LiF ribbon was put into a resistance heating boat made of molybdenum, and Al, 1.3 g was attached to another resistance heating boat made of molybdenum. Thereafter, the vacuum layer was depressurized to 2 × 10 ⁻⁴ Pa, and then the LiF boat was heated to 500 ° C. to deposit LiF at a deposition rate of 0.1 to 0.2 nm / second, and then by a resistance heating method. A boat containing Al was heated to 800 ° C. from the other boat, and Al was deposited at a deposition rate of 1.2 to 1.7 nm / second. Under the above conditions, a metal electrode of LiF and Al was deposited on the electron transport layer by 1 nm and 400 nm, respectively, to form a counter electrode.

When the obtained organic EL device was made to emit light using ITO as an anode and an Al electrode as a cathode, the green light emission with a current density of 10 mA / cm ² and uniform luminance of about 2000 cd / m ² due to Ir (ppy) ₃ was obtained. Was observed.

A high performance liquid chromatography method was adopted as a method for measuring the content of the specific hydrocarbon.
<Preparation of sample>
When the organic compound layer is deposited by resistance heating, the sample is placed on one of the patterns provided on the mask, and a glass substrate for sample preparation is placed on the glass surface. ) Was prepared by taking it out as it was and storing it in a clean container, without sealing like a device.
<Quantitative measurement>
Next, the organic material adhering to the glass substrate was scraped off with a spatula to obtain a powdery sample, which was extracted with a solvent. This sample is quantitatively measured by high performance liquid chromatography.
In the measurement, the specific hydrocarbon to be removed in the cleaning process has a molecular weight of 300 to 750, so that the molecular weight within this range was used as the measurement target.
In actual measurement, many molecules having a molecular weight in the above range were detected, and the content of the specific hydrocarbon was calculated from the sum of the masses of the individual molecules.

  Some variation in the content was observed depending on the measurement sample, but the content range was increased to 1 wt. % Could be controlled.

  The measurement of light emission luminance was carried out with a luminance meter while passing a constant current. (The same applies to the following examples.)

The measurement results are shown below.
The content of the specific hydrocarbon is 6 to 8% by mass in the case of no cleaning or once, 5 to 3% by mass in the case of 2 times, and 1 to 3 in the case of 3 times according to measurement by high performance chromatography. In the case of 2 mass% and 4 times, it was 1 mass% or less.
That is, when the chamber cleaning is performed once, the component analysis is performed by high performance liquid chromatography. As a result, the specific hydrocarbon is contained in about 6 to 8% by mass. It was about 200 hours.
When the chamber cleaning was performed twice, it was found that about 4% by mass of the specific hydrocarbon was mixed. When these elements were allowed to emit light continuously, the luminance half-life was 580 hours on average.
When the chamber cleaning was performed three times, it was found that about 2% by mass of the specific hydrocarbon was mixed. The luminance half time when this device was allowed to emit light was 680 hours on average.
Further, it was found that the specific hydrocarbon was less than 1% by mass (below the detection limit) when the chamber cleaning was performed four times or more. The luminance half time when this device was allowed to continuously emit light was 700 hours on average. The results are summarized in Table 1.

  In addition, it is identified by GP-MS and a liquid chromatography method that the specific hydrocarbon detected in the present Example is derived from Alcatel 120 (oil for Alcatel's rotary pump) used as a rotary pump oil. And a hydrocarbon having a molecular weight of 450 to 700.

  From the above, in the organic EL device of the example manufactured by performing the craning process, the time when the content of impurities (specific hydrocarbon) is small and the half time of luminance is reduced by half (luminance half time), It was confirmed that the luminance half-time is shortened as the content increases.

[Example 2]
In this example, a rotary pump oil (Alcatel 120) was added to the sample, and the amount added was intentionally increased stepwise for evaluation.
The sample was sample No. 1 in Example 1. It was produced by depositing rotary pump oil together with the material of the light emitting layer at the time of forming the light emitting layer of No. 3 (sample subjected to the cleaning process three times).
As a result, when the rotary pump oil was not added, the luminance half-life time was 700 hours, whereas when it was about 2% by mass (measured by high performance liquid chromatography, the same applies hereinafter), about 690 hours, It was 570 hours at 5% by mass and 300 hours at about 8% by mass. The results are summarized in Table 2.

[Example 3]
In the organic EL device manufactured in Example 1, instead of Ir (ppy) ₃ which is a green light emitting material used for the light emitting layer, a Firic (corresponding structure, peak wavelength: 466 nm) corresponding to blue light emission is used as the light emitting material. An organic EL element was produced in the same manner as in Example 1 except that.

When the obtained organic EL element was made to emit light using ITO as an anode and an Al electrode as a cathode, a uniform blue emission with a current density of 2.5 mA / cm ² and a luminance of about 360 cd / m ² caused by Ferpic was observed. did.

  Also in the present example, the “specific hydrocarbon amount (impurity amount)” and the “luminance half-life” in the case of being performed a single time and in the case of being performed multiple times are evaluated in the same manner as in Example 1. Went.

The measurement results are shown below.
When the chamber cleaning is performed once, component analysis is performed by high performance liquid chromatography. As a result, the specific hydrocarbon is contained in about 6 to 8% by mass, and the luminance half time when this element is continuously emitted is about 12 hours. Met.
When the chamber cleaning was performed twice, it was found that about 4% by mass of the specific hydrocarbon was mixed. The luminance half time when this element was continuously emitted was an average of 25 hours.
When the chamber cleaning was performed three times, it was found that the specific hydrocarbon was mixed in about 3% by mass. The luminance half time when this element was continuously emitted was an average of 55 hours.
When the chamber cleaning was performed four times or more, the specific hydrocarbon was found to be less than 1% by mass (below the detection limit). The luminance half time when this element was continuously emitted was an average of 60 hours. The results are summarized in Table 3.

  As shown in Table 3, even in the case of using an element that uses Firic as the light-emitting material, the element with a small content of impurities (specific hydrocarbons) has a long time to reduce the initial luminance by half (luminance half-time), and the impurities It was found that the luminance half-time is shortened when the amount is large.

[Example 4]
In the present example, in the case of an element using Firpic as a light emitting material, a rotary pump oil (Alcatel 120) was added to a sample, and the amount added was intentionally increased step by step for evaluation.
The sample was No. 1 in Example 3. It was produced by evaporating rotary pump oil together with the raw material of the light emitting layer at the time of forming the light emitting layer of No. 11 (sample subjected to the cleaning process three times).
As a result, when the rotary pump oil was not added, the luminance half-life was 60 hours, whereas it was about 2% by mass (measured by high performance liquid chromatography; the same applies hereinafter) for about 54 hours. It was 26 hours at 5% by mass and 12 hours at about 8% by mass. The results are summarized in Table 4.

  From the above Examples 1 to 4, it was found that in blue light emission having a wavelength shorter than that of green light emission, the effect becomes remarkable at a low impurity concentration.

[Example 4]
In this example, 1-docosene, which is a kind of aliphatic hydrocarbon, was intentionally added and evaluated as an example containing an aliphatic hydrocarbon (specific hydrocarbon).
The sample was No. 1 in Example 1. It was produced by evaporating 1-docosene together with the raw material of the light emitting layer at the time of forming the light emitting layer of 3 (sample subjected to the cleaning process three times).
As a result, in the case where 1-docosene was not added, the luminance half-life was 680 hours, whereas in the case of about 2% by mass (measured by high performance liquid chromatography, the same applies hereinafter), 670 hours, It was 560 hours at 8% by mass and 310 hours at 8% by mass. The results are summarized in Table 5.

  As shown in the above examples, it was confirmed that the luminance half-life was related to the content of impurities (specific hydrocarbons) in the organic compound layer. Therefore, the organic EL device obtained by the manufacturing method of the present invention that can reduce such impurities (organic EL device of the present invention) has a small attenuation of light emission luminance due to long-term driving and is excellent in durability. It turns out that it is an organic electroluminescent element.

Claims (8)

A method for producing an organic electroluminescent element, comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Aromatic hydrocarbons and alicyclic hydrocarbons having an optical band gap (Eg) of 400 nm or less in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer among the layers included in the organic compound layer. And a cleaning step for reducing the content of aliphatic hydrocarbons to less than 5% by mass per layer;
A method for producing an organic electroluminescent element, comprising: a vapor deposition step. A method for producing an organic electroluminescent element, comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer, the molecular weight is 300 to 750, the aromatic hydrocarbon, the alicyclic hydrocarbon, and the aliphatic A cleaning step for reducing the hydrocarbon content to less than 5% by weight per layer;
A method for producing an organic electroluminescent element, comprising: a vapor deposition step.   The method for producing an organic electroluminescent element according to claim 1, wherein the organic light emitting layer contains at least one phosphorescent light emitting material.   The method for manufacturing an organic electroluminescent element according to claim 3, wherein the peak emission wavelength of the phosphorescent material contained in the organic light emitting layer is 550 nm or less. An organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer has an optical band gap (Eg) of 400 nm or less, an aromatic hydrocarbon, an alicyclic carbonization An organic electroluminescent element, wherein the content of hydrogen and aliphatic hydrocarbon is less than 5% by mass per layer. An organic electroluminescent device comprising an organic compound layer including at least an organic light emitting layer between a pair of electrodes, wherein the organic compound layer is formed by vapor deposition,
Among the layers included in the organic compound layer, in at least one of the charge injection layer, the charge transport layer, and the organic light emitting layer, the molecular weight is 300 to 750, the aromatic hydrocarbon, the alicyclic hydrocarbon, and the fat An organic electroluminescent element, wherein the content of the group hydrocarbon is less than 5% by mass per layer.   The organic electroluminescent device according to claim 5 or 6, wherein the organic light emitting layer contains at least one phosphorescent light emitting material.   The organic electroluminescence device according to claim 7, wherein the phosphorescent material contained in the organic light emitting layer has a peak emission wavelength of 550 nm or less.