JP5831459B2 - ORGANIC ELECTROLUMINESCENT ELEMENT AND LIGHTING DEVICE - Google Patents

Description

  The present invention relates to an organic electroluminescence element that contains a plurality of phosphorescent dopants having different emission wavelengths, and particularly emits white light, and an illumination device using the same.

  As a light-emitting electronic display device, there is an electroluminescence display (hereinafter abbreviated as ELD). As a constituent element of ELD, an inorganic electroluminescence element (hereinafter also referred to as an inorganic EL element) and an organic electroluminescence element (hereinafter also referred to as an organic EL element) can be given. Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic electroluminescence device has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and excitons (exciton) are injected by injecting electrons and holes into the light emitting layer and recombining them. ), Which emits light by using light emission (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several V to several tens of V, and further self-emission. Since it is a mold, it has a wide viewing angle, high visibility, and a thin, completely solid element, and thus has attracted attention from the viewpoints of space saving and portability.

  Another major feature of the organic electroluminescence element is that it is a surface light source, unlike main light sources that have been put to practical use, such as light-emitting diodes and cold-cathode tubes. Applications that can effectively utilize this characteristic include illumination light sources and various display backlights. In particular, it is also suitable for use as a backlight of a liquid crystal full color display whose demand has been increasing in recent years.

  When the organic electroluminescence element is used as such an illumination light source or a display backlight, it is used as a light source that exhibits white or a so-called light bulb color (hereinafter collectively referred to as white). In order to obtain white light emission with an organic electroluminescence element, a method of adjusting a plurality of light emitting dopants having different emission wavelengths in one element and obtaining white color by mixing, a multicolor light emitting pixel, for example, blue, green, red Examples of the method include obtaining a white color by mixing three colors and emitting light simultaneously, and obtaining a white color using a color conversion dye (for example, a combination of a blue light emitting material and a color conversion fluorescent dye).

  However, judging from various demands required for light sources for illumination and backlights, such as low cost, high productivity, and simple driving method, a plurality of light emitting dopants having different light emission wavelengths are adjusted in one element to mix colors. The method of obtaining a white color is effective for these applications, and in recent years, research and development by this method has been vigorously advanced.

  The method for obtaining white light by the above-described method will be described in more detail. A method for obtaining white by a mixed color method using two-color light emitting dopants having complementary colors in the element, for example, a blue light emitting dopant and a yellow light emitting dopant, For example, a method of obtaining white color by a mixed color method using three or more luminescent dopants of green and red.

  For example, a method for obtaining a white organic electroluminescent element by doping high-efficiency phosphors of blue, green, and red as a light emitting material is disclosed (for example, see Patent Documents 1 and 2). .

  In addition, in an organic electroluminescence device that emits white light, the layers having different emission colors are not separated from each other, but two or more colors of luminescent dopants are allowed to coexist in one layer, and relative to the luminescent dopant having high emission energy. There is a method of emitting multiple colors by energy transfer to a light emitting dopant with low efficiency. This method is one of the effective methods for obtaining a white light-emitting organic EL device because the number of organic layers can be reduced and the amount of light-emitting dopant used can be reduced. For example, Patent Document 3 discloses an organic electroluminescent device having a configuration in which a red light emitting layer and a blue light emitting layer are sequentially provided from an anode, and the red light emitting layer contains at least one green light emitting dopant. Is disclosed.

  By the way, in recent years, a phosphorescent dopant capable of obtaining a higher-luminance organic electroluminescence device has been actively developed for fluorescent materials (see, for example, Patent Document 4 and Non-Patent Documents 1 and 2). The light emission from the conventional fluorescent material is light emission from the excited singlet, and the generation ratio of the singlet exciton and the triplet exciton is 1: 3. Therefore, the generation probability of the luminescent excited species is 25%. On the other hand, in the case of a phosphorescent dopant using light emission from an excited triplet, the upper limit of the internal quantum efficiency is 100% due to the exciton generation ratio and the internal conversion from a singlet exciton to a triplet exciton. Therefore, in principle, the luminous efficiency is up to four times that in the case of the fluorescent luminescent dopant.

  However, by using a phosphorescent dopant, two or more colors of luminescent dopants can coexist in one layer, and a multicolor light is emitted by energy transfer from a luminescent dopant having a high luminescence energy to a dopant having a relatively low efficiency. When it is intended to obtain an organic electroluminescent element, it is easier to ensure relatively high chromaticity driving conditions and environmental stability, compared with the case of obtaining a white color by laminating a plurality of layers having different emission colors. However, it has been found that the stability of chromaticity with respect to driving conditions, device driving aging or storage aging is not necessarily at a sufficient level. In particular, in lighting light source applications, there is a strict requirement for the stability of the emission color, and in order to put an organic electroluminescence element into practical use as an illumination light source, how to ensure chromaticity stability is an important issue. It has become.

  For example, Patent Document 5 discloses a method for facilitating charge transfer by changing the concentration of the light emitting material in the light emitting layer, thereby reducing the voltage and increasing the light emission efficiency. Although a method is disclosed, a configuration example of a white element using a phosphorescent material that emits blue light is not disclosed. In Patent Document 7, there is a description regarding the concentration gradient of the blue phosphorescent dopant, but there is no description or suggestion regarding the chromaticity stability in the white element and the white element, and the HOMO level of the phosphorescent material in the present invention is There is no description about the relationship.

JP-A-6-207170 JP 2004-235168 A International Publication No. 2004/077786 Pamphlet US Pat. No. 6,097,147 Japanese Patent No. 3778623 Japanese Patent No. 4181895 Special table 2010-515255

M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000)

  The present invention has been made in view of the above problems, and the problem to be solved is that in an organic electroluminescence device having a plurality of phosphorescent dopants having different emission wavelengths and emitting white light, power efficiency and storage stability. Another object of the present invention is to provide a white phosphorescent organic electroluminescence element which is excellent in operability and excellent in driving voltage, high-temperature storage and chromaticity stability in continuous driving, and a lighting device using the same.

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

1. At least one phosphorescent dopant A having at least one emission maximum in a short wavelength region of 480 nm or less and at least one phosphorescent dopant B having an emission maximum in a long wavelength region of 580 nm or more between opposed electrodes. The phosphorescent light-emitting dopant A has a light-emitting layer contained in the same layer, and the phosphorescent light-emitting dopant A is at least one compound selected from the compounds represented by the following general formulas (A) to (C). It is contained at a high concentration on the anode side of the light emitting layer, is contained with a concentration distribution so as to become a low concentration toward the cathode side, and the content of the phosphorescent dopant A at the end on the anode side is An organic electroluminescence device characterized by being 60 mass% or more and less than 100 mass% of the total mass of the anode side end of the light emitting layer.

〔式中、Ｒａは水素原子、脂肪族基、芳香族基または複素環基を表し、Ｒｂ、Ｒｃは各々水素原子、アルキル基、アリール基、アルコキシル基またはハロゲン原子を表し、Ａ１は芳香族環または芳香族複素環を形成するのに必要な残基を表し、ＭはＩｒまたはＰｔを表す。Ｘ_１、Ｘ_２は各々炭素原子、窒素原子または酸素原子を表し、Ｌ_１はＸ_１及びＸ_２と共に２座の配位子を形成する原子群を表す。ｍ１は１、２または３の整数を表し、ｍ２は０、１または２の整数を表すが、ｍ１＋ｍ２は２または３である。〕

〔式中、Ｒａは水素原子、脂肪族基、芳香族基または複素環基を表し、Ｒｂ、Ｒｃ、Ｒｂ_１、Ｒｃ_１は各々水素原子を表し、Ａ１は芳香族環または芳香族複素環を形成するのに必要な残基を表し、ＭはＩｒまたはＰｔを表す。Ｘ_１、Ｘ_２は各々炭素原子、窒素原子または酸素原子を表し、Ｌ_１はＸ_１及びＸ_２と共に２座の配位子を形成する原子群を表す。ｍ１は１、２または３の整数を表し、ｍ２は０、１または２の整数を表すが、ｍ１＋ｍ２は２または３である。〕

〔式中、Ｒａは水素原子、脂肪族基、芳香族基または複素環基を表し、Ｒｂ、Ｒｃは各々水素原子またはアルキル基を表し、Ａ１は芳香族環または芳香族複素環を形成するのに必要な残基を表し、ＭはＩｒまたはＰｔを表す。Ｘ_１、Ｘ_２は各々炭素原子、窒素原子または酸素原子を表し、Ｌ_１はＸ_１及びＸ_２と共に２座の配位子を形成する原子群を表す。ｍ１は１、２または３の整数を表し、ｍ２は０、１または２の整数を表すが、ｍ１＋ｍ２は２または３である。〕
２．前記燐光発光ドーパントＡの最高電子占有準位が、５．３ｅＶより浅いことを特徴とする前記１に記載の有機エレクトロルミネッセンス素子。

[Wherein, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represents a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group or a halogen atom, and A1 represents an aromatic ring. Alternatively, it represents a residue necessary for forming an aromatic heterocyclic ring, and M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]

[Wherein, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb, Rc, Rb ₁ and Rc ₁ each represent a hydrogen atom, and A1 represents an aromatic ring or an aromatic heterocyclic ring. Represents the residue necessary to form, M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]

[In the formula, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represent a hydrogen atom or an alkyl group, and A1 forms an aromatic ring or an aromatic heterocyclic ring. And M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]
2. 2. The organic electroluminescence device according to 1 above, wherein the phosphorescent dopant A has a highest electron occupation level shallower than 5.3 eV.

  3. 3. The light emitting layer containing the phosphorescent dopants A and B contains at least one phosphorescent dopant C having an emission maximum in a wavelength range of 500 nm or more and less than 580 nm, Organic electroluminescence device.

  4). 4. The organic electroluminescent device according to any one of 1 to 3, wherein the light emitting layer containing the phosphorescent dopants A and B contains a host compound represented by the following general formula (a): .

〔式中、Ｘは、ＮＲ′、Ｏ、Ｓ、ＣＲ′Ｒ″またはＳｉＲ′Ｒ″を表す。Ｒ′、Ｒ″は、各々水素原子、アルキル基または芳香族炭化水素基を表す。Ａｒは芳香族環を表す。ｎは０から８の整数を表す。〕
５．前記５８０ｎｍ以上の長波長域に発光極大を有する少なくとも１種の燐光発光ドーパントＢの濃度が、発光層の膜厚方向で一定濃度であることを特徴とする前記１から４のいずれか一項に記載の有機エレクトロルミネッセンス素子。
６．前記１から５のいずれか１項に記載の有機エレクトロルミネッセンス素子を用いることを特徴とする照明装置。

[Wherein, X represents NR ′, O, S, CR′R ″ or SiR′R ″. R ′ and R ″ each represent a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. Ar represents an aromatic ring. N represents an integer of 0 to 8.]
5. Any one of 1 to 4 above, wherein the concentration of the at least one phosphorescent dopant B having an emission maximum in a long wavelength region of 580 nm or more is a constant concentration in the film thickness direction of the light emitting layer. The organic electroluminescent element of description.
6 . 6. An illuminating device using the organic electroluminescence element according to any one of 1 to 5 above.

  According to the present invention, in an organic electroluminescent device having a plurality of phosphorescent dopants having different emission wavelengths, and particularly emitting white light, it is excellent in power efficiency and storage stability, and has a driving voltage, color at high temperature storage and continuous driving. It is possible to provide a white phosphorescent organic electroluminescence element excellent in temperature stability and a lighting device using the same.

It is the schematic which shows an example of the illuminating device incorporating the organic EL element of this invention. It is sectional drawing which shows an example of the illuminating device incorporating the organic EL element of this invention.

  Hereinafter, details of each component of the white phosphorescent organic electroluminescence device of the present invention (hereinafter also referred to as the organic EL device of the present invention) will be described in order.

<< White chromaticity of organic electroluminescence element >>
The preferred chromaticity as the white display element in the present invention is that the correlated color temperature is 2500 K to 7000 K, and in the CIE1931 color system, the y value deviation width from the black body radiation at each color temperature is 0.1 or less. .

  The emission color of the organic EL device of the present invention and the compound related to the device is, for example, as shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). The result of measurement with a luminance meter CS-1000 (manufactured by Konica Minolta Sensing) is determined by the color when applied to the CIE chromaticity coordinates.

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

(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emission Layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode In the organic EL device of the present invention, the light emitting layer unit has at least one light emitting layer having a configuration satisfying the requirements defined in the present invention. Any number of layers may be used as long as it is present, but it is preferably composed of only one light emitting layer having a requirement satisfying the provisions of the present invention.

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

  The total thickness of the light emitting layer is not particularly limited, but it prevents the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color with respect to the driving current. From a viewpoint, it is preferable to adjust to the range of 5-200 nm, More preferably, it adjusts to the range of 20-150 nm. Moreover, as a film thickness of the light emitting layer which consists of a structure prescribed | regulated by this invention, it is preferable to adjust to the range of 5-200 nm, More preferably, it is adjusting to the range of 20-150 nm.

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

  In the present invention, in the same light emitting layer, at least one phosphorescent dopant A having at least one emission maximum in a short wavelength region of 480 nm or less, and at least one phosphorescence emission having an emission maximum in a long wavelength region of 580 nm or more. It has at least one light emitting layer containing the dopant B, and the phosphorescent dopant A has at least one partial structure selected from the general formulas (A) to (C), and further the phosphorescent dopant. A is contained in a high concentration on the anode side of the light emitting layer, and is contained with a concentration distribution so that the concentration becomes low toward the cathode side.

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

  The light emitting layer containing the phosphorescent dopants A and B preferably further includes at least one phosphorescent dopant C having an emission maximum in a wavelength region of 500 nm or more and less than 580 nm in order to improve color rendering. In the light emitting layer, the phosphorescent dopant A and the phosphorescent dopants B to C have a molar concentration ratio in which the phosphorescent dopant A is 10 times or more of the phosphorescent dopant B or C in order to obtain suitable white light emission. preferable.

  Next, the concentration distribution of the phosphorescent dopant A in the light emitting layer will be described.

  In the present invention, the light-emitting dopant A is contained at a high concentration on the anode side of the light-emitting layer, and is distributed with a concentration gradient so that the concentration decreases toward the cathode side. The phosphorescent light emitting dopant A average content in the portion from the anode side end portion to the light emitting layer central portion of the light emitting layer may be larger than the average content from the cathode side end portion to the light emitting layer central portion, preferably the anode side end. It is preferable that the portion has the highest concentration and monotonously decreases from the anode side end portion to the cathode side end portion. Monotonically decreasing means that there is no maximum concentration portion except for the anode side end of the light emitting layer. In the present invention, the anode side end portion refers to a region of the thinner one of the thickness of 5 nm from the anode side interface of the light emitting layer or 1/20 of the entire light emitting layer, Denotes a region having a smaller thickness of 5 nm from the cathode side interface of the light emitting layer or 1/20 of the thickness of the entire light emitting layer.

  One content of the phosphorescent dopant A at the end on the anode side in the light emitting layer is 60% by mass or more and less than 100% by mass. When the content of the phosphorescent light-emitting dopant A is less than 60% by mass, the power efficiency is lowered, and the chromaticity stability over time of driving tends to be inferior. When the content is 100% by mass, the chromaticity stability tends to be inferior in the storage time of the device and the change in driving voltage.

  The light-emitting layer having the structure defined in the present invention provides a white phosphorescent organic electroluminescence device that is excellent in power efficiency and excellent in chromaticity versus drive voltage, versus drive aging, and in stability during device storage. . The mechanism of action that brings about the effects of the present invention is not necessarily elucidated and is not speculative. However, phosphorescent layers, particularly phosphorescent layers that emit blue light, have a large energy gap, and electrons or holes. It is expected that there will be a large barrier to the injection of such charges into the light emitting layer. The structure of the present invention is expected to improve the injection of this charge into the light-emitting layer, but the effect of the present invention is not obtained in any combination with any material, and the phosphorescence of the present invention is not particularly effective. It has been found that a remarkable effect can be obtained in combination with the light emitting dopant A and further with the host compound.

  For example, Japanese Patent No. 3786023 discloses a method for facilitating charge transfer by changing the concentration of the light emitting material in the light emitting layer to lower the voltage and increase the light emission efficiency. A similar method is disclosed, but a configuration example of a white element using a phosphorescent material that emits blue light is not disclosed, and in particular, the effect of the present invention regarding chromaticity stability cannot be predicted. Absent. Furthermore, the remarkable effect in combination with the phosphorescent material prescribed | regulated by this invention cannot be foreseen. JP-T-2010-515255 discloses the concentration gradient of the blue phosphorescent dopant, but does not describe the white element and the chromaticity stability in the white element, and the HOMO level of the phosphorescent material in the present invention. It does not foresee any significant effect on the relationship.

<Measurement method of dopant distribution>
There are several methods for measuring the distribution of the dopant in the depth direction, but dynamic secondary ion mass spectrometry (D-SIMS) is preferred when there are specific elements. D-SIMS can analyze the amount of elements in the film with high sensitivity and can follow the concentration change of elements in the depth direction. As for secondary ion mass spectrometry, for example, Japanese Society for Surface Science “Secondary ion mass spectrometry (Surface Science and Technology Selection)” (Maruzen) can be referred to.

In dynamic secondary ion mass spectrometry, a sample surface is irradiated with an ion beam called primary ions under a high vacuum of about 1 × 10 ⁻⁸ Pa to perform sputtering. This is a method of analyzing elements present on the surface by mass spectrometry of secondary ions in the constituent particles released thereby. Although the surface is sputtered and scraped off, it is possible to analyze the change in element concentration from the surface to a depth of the order of μm or more, although it is a destructive analysis.

As the primary ions, for example, metal ion species such as Cs ⁺ and O ₂ ⁺ are preferable, but which ion species is preferably used depends on the element to be measured.

When it is desired to measure the compound itself, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) method is preferable. In this case, the distribution of the dopant compound in the depth direction can be known by measuring the distribution of fragment ions obtained from the compound in the oblique cross-section portion that has been cut off obliquely and the shaved cross-section. Examples of the oblique cutting method include a method using an ultramicrotome used for preparing a sample for an electron microscope, and a method using a precision oblique cutting device such as a die-plautes Cycus NN type. Regarding the ToF-SIMS method, for example, the Japan Surface Science Society “Secondary Ion Mass Spectrometry (Surface Science and Technology Selection)” (Maruzen) can be referred to. In the ToF-SIMS method, sputtering is performed by irradiating the sample surface with an ion beam called primary ions under a high vacuum of about 1 × 10 ⁻⁸ Pa. By making the primary ion beam very low current and pulsed, very gentle sputtering occurs, and by analyzing the compounds present on the surface by mass analysis of the secondary ions emitted by it, is there. By measuring while scanning the primary ions, the distribution of secondary ions emitted by sputtering can be measured. As the primary ions, for example, metal ion species such as Ga ⁺ , In ⁺ , Bi ⁺ , and Au ⁺ and their cluster ions are preferable. Which ion species is preferably used depends on the element to be measured.

  For example, when forming by vapor deposition, the concentration gradient of the light-emitting dopant is formed by changing the vapor deposition ratio with other co-deposition components, but after formation, by performing sputtering in the depth direction by the above method, The distribution in the depth direction can be measured.

[Host compound]
Next, a host compound and a light emitting dopant (hereinafter also referred to as a light emitting host compound and a light emitting dopant compound) contained in the light emitting layer will be described.

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

  As a host compound, a host compound may be used independently or may be used in combination of multiple types.

  The luminescent host compound used in the present invention is not particularly limited in terms of structure, but representative compounds include carbazole derivatives, triarylamine derivatives, aromatic borane derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, Those having a basic skeleton such as a furan derivative or an oligoarylene compound, or a carboline derivative or a diazacarbazole derivative (here, a diazacarbazole derivative is at least one carbon of a hydrocarbon ring constituting a carboline ring of a carboline derivative) Represents an atom substituted with a nitrogen atom.) And the like.

  As the light emitting host compound used in the light emitting layer according to the present invention, the compound represented by the general formula (a) is preferable.

  In the general formula (a), X represents NR ′, O, S, CR′R ″ or SiR′R ″, and R ′ and R ″ each represents a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. Ar represents an aromatic ring, and n represents an integer of 0 to 8.

  Specific examples of the alkyl groups and aromatic hydrocarbon groups represented by R ′ and R ″ in X in the general formula (a) include alkyl groups such as methyl, ethyl, propyl, and isopropyl. Group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and the like, and as an aromatic hydrocarbon group (also called aromatic carbocyclic group, aryl, etc.) Is, for example, phenyl, p-chlorophenyl, mesityl, tolyl, xylyl, naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, biphenylyl, etc. It is done.

  These groups may be further substituted with the following substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

  Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), Cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, 1-propenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, isopropenyl group) Etc.), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, Xylyl, naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl Phenanthryl, indenyl, pyrenyl, biphenylyl, etc.), aromatic heterocyclic groups (eg, furyl, thienyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, imidazolyl, pyrazolyl, thiazolyl) Group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), phthalazinyl group, etc. Ring groups (eg, pyrrolidyl, imidazolidyl, morpholyl, oxazolidyl, etc.), alkoxy groups (eg, methoxy, ethoxy, propyloxy, pentyloxy, hexyloxy, octyloxy, dodecyloxy, etc.) ), A cycloalkoxy group ( For example, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, Dodecylthio group etc.), cycloalkylthio group (eg cyclopentylthio group, cyclohexylthio group etc.), arylthio group (eg phenylthio group, naphthylthio group etc.), alkoxycarbonyl group (eg methyloxycarbonyl group, ethyloxycarbonyl group, Butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfur Amoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthyl) Aminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, Phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, Tilcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (eg, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group) Group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, Dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl Group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexyl) Ureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexyl) Sulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, Acetylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridyl group) Sulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group) Etc.), halogen atoms (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon groups (eg fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group etc.), shear Group, nitro group, hydroxy group, a mercapto group, a silyl group (e.g., trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, a phenyl diethyl silyl group and the like), a phosphono group, and the like.

  In the general formula (a), X is preferably NR ′ or O, and R ′ is particularly preferably an aromatic hydrocarbon group.

  In the general formula (a), examples of the aromatic ring represented by Ar include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. Further, the aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent as described later.

  In the general formula (a), examples of the aromatic hydrocarbon ring represented by Ar include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, Examples include a pyranthrene ring and anthraanthrene ring. These rings may further have a substituent.

  In the general formula (a), examples of the aromatic heterocycle represented by Ar include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a triazine ring. , Benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indazole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, cinnoline ring, quinoline Ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (showing a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom), etc. Can be mentioned. These rings may further have a substituent.

  Among these, in the general formula (a), the aromatic ring represented by Ar is preferably a carbazole ring, a carboline ring, a dibenzofuran ring, or a benzene ring, and particularly preferably used is a carbazole ring, A carboline ring or a benzene ring. Among these, a benzene ring having a substituent is preferable, and a benzene ring having a carbazolyl group is particularly preferable.

  In the general formula (a), the aromatic ring represented by Ar is preferably a condensed ring having three or more rings, as shown below, and is an aromatic hydrocarbon in which three or more rings are condensed. Specific examples of the condensed ring include naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, Triphenylene ring, coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthoperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene ring , Naphthocoronene ring, Ovalene ring, Anse Antoren ring and the like. In addition, these rings may further have a substituent.

  Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, A Tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan Tren ring (naphthaldehyde thiophene ring), and the like. In addition, these rings may further have a substituent.

  Here, in the general formula (a), the substituents that the aromatic ring represented by Ar may have are the same as the substituents represented by R ′ and R ″.

  In the general formula (a), n represents an integer of 0 to 8, preferably 0 to 2, and particularly preferably 1 or 2 when X is O or S.

  Specific examples of the luminescent host compound represented by the general formula (a) and other luminescent host compounds that can be preferably used in the present invention are shown below, but are not limited thereto.

また、本発明に用いるホスト化合物は、低分子化合物でも、繰り返し単位を有する高分子化合物でもよく、ビニル基やエポキシ基のような重合性基を有する低分子化合物（蒸着重合性発光ホスト）でもいい。

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

  As the host compound, a compound having a hole transporting ability and an electron transporting ability, which prevents emission of longer wavelengths and has a high Tg (glass transition temperature) is preferable.

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

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

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

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

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

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

[Luminescent dopant]
Next, the light emitting dopant according to the present invention will be described.

  As the light-emitting dopant according to the present invention, a phosphorescent dopant (hereinafter also referred to as a phosphorescent emitter, a phosphorescent compound, or a phosphorescent compound) is used.

(Phosphorescent emitter)
The phosphorescent material according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield of 25 ° C. In this case, the phosphorescence quantum yield is preferably 0.1 or more.

  The phosphorescent quantum yield can be measured by, for example, the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence emitter according to the present invention achieves the above phosphorescence quantum yield (0.01 or more) in any solvent. It only has to be done.

  There are two types of phosphorescent light emitting principles. One type is the recombination of carriers on the host compound to which carriers are transported, and an excited state of the host compound is generated. In another type, the phosphorescent emitter becomes a carrier trap, and carrier recombination occurs on the phosphorescent emitter, resulting in emission from the phosphorescent emitter. Although it is a carrier trap type in which light emission can be obtained, in any case, the energy of the excited state of the phosphorescent emitter is required to be lower than the energy of the excited state of the host compound.

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

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

  Among the phosphorescent dopants according to the present invention, the phosphorescent dopant B or the phosphorescent dopant C is selected from these. Specific examples of compounds used as phosphorescent emitters, that is, phosphorescent dopant B or phosphorescent dopant C, are shown below. These compounds are described in, for example, Inorg. Chem. 40, 1704-1711, and the like.

（一般式（Ａ）〜（Ｃ）で表される部分構造）
本発明においては、前記燐光発光ドーパントＡが、前記一般式（Ａ）〜（Ｃ）で表される化合物から選ばれる少なくとも１つの化合物であることを特徴とする。

(Partial structure represented by formulas (A) to (C))
In the present invention, the phosphorescent dopant A is at least one compound selected from the compounds represented by the general formulas (A) to (C).

In the general formula (A), Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represents a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group or a halogen atom, and A1 Represents a residue necessary for forming an aromatic ring or an aromatic heterocyclic ring, and M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3.

In the general formula (B), Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb, Rc, Rb ₁ and Rc ₁ each represents a hydrogen atom, and A1 represents an aromatic ring. Alternatively, it represents a residue necessary for forming an aromatic heterocyclic ring, and M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3.

In the general formula (C), Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represents a hydrogen atom or an alkyl group, and A1 represents an aromatic ring or an aromatic group. It represents a residue necessary for forming a heterocyclic ring, and M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3.

  In the general formulas (A) to (C), Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and the aliphatic group represented by Ra includes an alkyl group (for example, a methyl group, an ethyl group, Group, propyl group, butyl group, pentyl group, isopentyl group, 2-ethyl-hexyl group, octyl group, undecyl group, dodecyl group, tetradecyl group), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group), and the like. As the aromatic group, for example, phenyl group, tolyl group, azulenyl group, anthranyl group, phenanthryl group, pyrenyl group, chrysenyl group, naphthacenyl group, o-terphenyl group, m-terphenyl group, p-terphenyl group, Examples include acenaphthenyl group, coronenyl group, fluorenyl group, perylenyl group, etc. It may have. As the heterocyclic group, for example, pyrrolyl group, indolyl group, furyl group, thienyl group, imidazolyl group, pyrazolyl group, indolizinyl group, quinolinyl group, carbazolyl group, indolinyl group, thiazolyl group, pyridyl group, pyridazinyl group, thiadiazinyl group, An oxadiazolyl group, a benzoquinolinyl group, a thiadiazolyl group, a pyrrolothiazolyl group, a pyrrolopyridazinyl group, a tetrazolyl group, an oxazolyl group, a chromanyl group, and the like can be mentioned, and these groups each may have a substituent.

  In the general formula (A), Rb and Rc each represent a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group or a halogen atom. Specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, An isopropyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group and the like can be mentioned. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkoxyl group include a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, A bromine atom etc. are mentioned.

In the general formula (B), Rb, Rc, Rb ₁ and Rc ₁ each represent a hydrogen atom.

  In the general formula (C), Rb and Rc each represent a hydrogen atom or an alkyl group. Specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and tert-butyl. Group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and the like.

  Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), A cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), an alkenyl group (eg, vinyl group, allyl group, etc.), an alkynyl group (eg, ethynyl group, propargyl group, etc.), an aryl group (eg, phenyl group, naphthyl group). Etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.), complex A cyclic group (for example, pyrrolidyl group, imidazolidyl group, Ruphoryl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxyl group (eg, cyclopentyloxy group) Cyclohexyloxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group etc.), A cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxy) Rubonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylamino) Sulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group) An acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbo group) Nyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group) , Dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2- Ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoy Groups (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, Phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group) Naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group) Cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl) Group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, Butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (for example, Fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxyl group, mercapto Group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

  In the general formulas (A) to (C), A1 represents a residue necessary for forming an aromatic ring or an aromatic heterocyclic ring. Examples of the aromatic ring include a benzene ring, a biphenyl ring, a naphthalene ring, and an azulene ring. , Anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring Naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthrene ring, etc., and the aromatic heterocycle includes furan ring, thiophene ring, pyridine ring, pyridazine ring , Pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring Imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, diazacarbazole ring (carbonization constituting carboline ring) A ring in which one of the carbon atoms of the hydrogen ring is further substituted with a nitrogen atom).

In the general formulas (A) to (C), X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom. L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . Specific examples of the bidentate ligand represented by X ₁ -L ₁ -X ₂ include, for example, a substituted or unsubstituted phenylpyridine group, phenylpyrazole group, phenylimidazole group, phenyltriazole group, phenyl, respectively. Examples thereof include a tetrazole group, a pyrazaball group, a picolinic acid, and an acetylacetone group. These groups may be further substituted with the substituents shown above.

  m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. Furthermore, it is preferable that m2 is 0.

  In the general formulas (A) to (C), M represents Ir or Pt, and Ir is particularly preferable. Moreover, as a compound represented by general formula (A)-(C), a tris body is preferable.

  Hereinafter, although the compound represented by the said general formula (A)-(C) of the light emission dopant which concerns on this invention is illustrated, it is not limited to these.

更に、本発明においては、前記発光ドーパントのイオン化ポテンシャルエネルギーが５．３ｅＶより小さいものであることが、高効率かつ色度の安定性を良好にする上で好ましい。即ち、燐光発光ドーパントＡの最高電子占有準位が、５．３ｅＶより浅いことが好ましい。

Furthermore, in the present invention, it is preferable that the ionization potential energy of the light emitting dopant is smaller than 5.3 eV from the viewpoint of high efficiency and good chromaticity stability. That is, it is preferable that the highest electron occupation level of the phosphorescent dopant A is shallower than 5.3 eV.

  The highest electron occupation level (HOMO) level (also referred to as ionization potential) of the phosphorescent dopant A can be obtained by using, for example, ultraviolet photoelectron spectroscopy (UPS). That is, the HOMO level can be measured by measuring the UPS of a single film of these compounds formed on a glass substrate.

  Specifically, for example, the value measured by ESCA 5600 UPS (ultraviolet photoemission spectroscopy) manufactured by ULVAC-PHI Co., Ltd. can be used.

《Middle layer》
In the organic EL device of the present invention, when a plurality of light emitting layers are provided, a non-light emitting intermediate layer (also referred to as an undoped region) may be provided between the light emitting layers.

  The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 to 50 nm, and more preferably in the range of 3 to 10 nm, which suppresses interaction such as energy transfer between adjacent light emitting layers and is organic. This is preferable because a large load is not applied to the current-voltage characteristics of the EL element.

  The material used for the non-light emitting intermediate layer may be the same as or different from the host compound of the light emitting layer, but may be the same as the host material of at least one of the adjacent light emitting layers. preferable.

  The non-light emitting intermediate layer may contain a compound (for example, a host compound) common to the non-light emitting layers, and each of the common host materials (here, the common host material is used) means phosphorescence. (In which the physicochemical characteristics such as luminescence energy and glass transition point are the same, or the host compound has the same molecular structure, etc.) Thus, even if the voltage (current) is changed, the hole and electron injection balance can be easily maintained. Furthermore, by using a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer, device fabrication, which is a major problem in conventional organic EL device fabrication, is achieved. Complexity can also be eliminated.

  Further, in order to optimally adjust the injection balance of holes and electrons, it is also preferable that the non-light emitting intermediate layer functions as a blocking layer described later, that is, a hole blocking layer and an electron blocking layer. .

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

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

  Details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, and the like. As a specific example, copper phthalocyanine Phthalocyanine buffer layer typified by (1), oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene, and the like. Moreover, it is also preferable to use the material described in Japanese translations of PCT publication No. 2003-519432 gazette.

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

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

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

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

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

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

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

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

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

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

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

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

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

  For the hole transport layer, the hole transport material may be selected from, for example, vacuum deposition method, spin coating method, casting method, LB method (Langmuir-Blodget method), ink jet method, spray method, printing method, slot type coater method, etc. The film can be formed by a known thin film forming method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is the range of 5 nm-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

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

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

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

  For the electron transport layer, the above-mentioned electron transport material may be a known material such as a vacuum deposition method, a spin coat method, a cast method, an LB method (Langmuir-Blodget method), an ink jet method, a spray method, a printing method, or a slot type coater method. The film can be formed by a thin film forming method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, it is the range of 5 nm-5 micrometers, Preferably it is the range of 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

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

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

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

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones, Cycloolefin resins such as polyether imide, polyether ketone imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned. An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability measured by a method according to JIS K 7129-1992 is 0.01 g / (m ² · 24 h · atm) or less, and the oxygen permeability measured by a method according to JIS K 7126-1992 is 1 × 10 ⁻³ g / (m ² · 24 h. ) Hereinafter, a high barrier film having a water vapor permeability of 1 × 10 ⁻³ g / (m ² · 24 h) or less is preferable, and both the water vapor permeability and the oxygen permeability are 1 × 10 ^−5. More preferably, it is g / (m ² · 24h) or less.

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

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

  Examples of the opaque support substrate include metal plates / films such as aluminum and stainless steel, opaque resin substrates, ceramic substrates, and the like.

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

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

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

In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Furthermore, the polymer film may have an oxygen permeability of 1 × 10 ⁻³ g / (m ² · 24 h) or less and a water vapor permeability of 1 × 10 ⁻³ g / (m ² · 24 h) or less. preferable. Further, it is more preferable that both the water vapor permeability and the oxygen permeability are 1 × 10 ⁻⁵ g / (m ² · 24 h) or less.

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

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

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

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

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

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

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

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

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

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of an anode material is formed on an appropriate support substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 10 to 200 nm. Is made. Next, an organic compound thin film is formed on the organic EL element material in this order: a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer.

As a method for thinning the organic compound thin film, as described above, the vapor deposition method, the wet process (spin coating method, casting method, ink jet method, printing method, LB method (Langmuir-Blodgett method), spray method, printing method, However, vacuum deposition, spin coating, ink-jet, printing, and slot-type coater methods are particularly preferred from the standpoint that a homogeneous film is easily obtained and pinholes are not easily formed. preferable. Further, different film forming methods may be applied for each layer. When the vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally the boat heating temperature is in the range of 50 ° C. to 450 ° C., and the degree of vacuum is 1 × 10 ⁻⁶ to 1 × 10 ^{−. 2} Pa, the deposition rate is 0.01 to 50 nm / second, the substrate temperature is −50 to 300 ° C., and the film thickness is 0.1 to 5 μm, preferably 5 to 200 nm. It is desirable. After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm. By providing, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

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

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

  As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, JP-A-63-314795), a method for forming a reflective surface on a side surface of an element (for example, JP-A-1-220394), a substrate, etc. A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the light emitting body and the light emitting body (for example, Japanese Patent Application Laid-Open No. 62-172691), lower refraction than the substrate between the substrate and the light emitting body A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), and a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (including between the substrate and the outside world) ( JP 1 No. -283751 Publication), and the like.

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

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

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

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

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

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

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

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

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

  The organic electroluminescent device of the present invention is formed in a specific direction by combining, for example, a so-called condensing sheet or a method of processing so as to provide a structure on a microlens array on the light extraction side of a support substrate (substrate). For example, a method of increasing the luminance in a specific direction by condensing light in the front direction with respect to the element light emitting surface can be applied.

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

  As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Co., Ltd. can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from an organic EL element, you may use a light-diffusion plate and a film together with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<Display device>
Next, a display device to which the organic EL element of the present invention is applied will be described.

  The organic EL element of the present invention is used for a multicolor or white display device. In the case of a multicolor or white display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, slot coater, or the like. When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

  Further, the cathode, the electron transport layer, the hole blocking layer, and the light emitting layer unit (having at least three layers of the above light emitting layers A, B, and C, and a non-light emitting intermediate layer between the light emitting layers) It is also possible to produce the hole transport layer and the anode in this order. When a DC voltage is applied to the multicolor or white display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

《Lighting device》
Next, an illumination device to which the organic EL element of the present invention is applied will be described.

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

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

  As described above, the white organic EL element of the present invention is taken out from the organic electroluminescence element by combining the CF (color filter) and arranging the element and the driving transistor circuit in accordance with the CF (color filter) pattern. Using white light as a backlight, blue light, green light, and red light are obtained through a blue filter, a green filter, and a red filter, so that a full-color organic electroluminescence display with a low driving voltage and a long life can be obtained.

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

  Taking advantage of the characteristics of the organic EL device of the present invention, it can be applied to various lighting fixtures and light emitting displays as shown below.

[For product display and display]
For product display and display, there are store product display, freezer / refrigerated showcase, light up of exhibits in museums, art galleries, exhibition halls, vending machines, play tables, traffic advertisements, etc.

  Store merchandise displays include decorative displays, showcases, POPs and signs for the store itself. Among stores, high-end brand shops, precious metals, fashion, high-end restaurants, and other stores that place emphasis on the brand image have a great influence on the store image that lighting gives, so lighting has been selected with strong attention This is a field. By using organic EL, the space for the light source and equipment can be omitted in the field of indirect lighting, which has created an atmosphere by devising the structure of the building so that the light source can not be seen directly, and no complicated structure is required When creating diffused light for interiors and signs, the shape of the light source cannot be seen through, so the space between the necessary light source and the diffuser can be omitted, and workability is improved. Also, as a tool for changing the image of the store, it takes advantage of the feature that it is a light source that does not take up space such as display shelves, floors, fixtures, etc., and it has design freedom, easy workability, and easy There is an advantage that it can be adopted.

  Frozen and refrigerated showcases are placed in supermarkets and convenience stores to make fresh foods such as vegetables, fruits, fresh fish, and meats full of beauty and freshness. Therefore, the lighting equipment is one of the important parts. By using an organic EL light source, low temperature emission has little effect on the cooling function, and since it is thin, the light source space can be greatly reduced, so the storage space can be expanded, and it is easy to select food with a smart design. It can be made easier. In addition, it can appeal to consumers with colored light that makes it easy to understand the goodness of food, contributing to sales.

  In order to light up exhibits at museums, art galleries, exhibition halls, etc., it is necessary to select a light source that is suitable for the conditions of use from the viewpoint of visual recognition and sunburn. Has been developed. Since the organic EL light source does not contain ultraviolet rays and the calorific value is low, there is no adverse effect on the exhibit, it is uniform glare with the surface light source, and it is possible to faithfully appreciate the display as it is with high color rendering. it can. In addition, since a large light source device is not required, it is possible to focus only on the exhibits without the need for extra equipment protruding in the field of view. Also, in large-scale exhibition halls such as shows, large-sized electric decorations that attract attention can be assembled relatively easily due to their lightweight and thin features.

  Vending machines use light sources for push buttons, product samples, and posters on the front of the vending machine. It is a field where the advantage of organic EL that does not take up a thin light source space can be utilized because the space for the additional function to be taken in and the storage space are combined with the size of the entire device, especially on the outlet Needs are high in poster space. In recent years, there are many devices that have game characteristics such as hit / miss along with sales, and it is possible to make further use of the benefits by installing a light source (video display) with a pixel control function on the front poster. Can do.

  There are pachinko and pachislots at the playground. In these playgrounds, it is most important for users to experience and enjoy amusement (games, gambling, etc.). Although there is a merit of thinness that can reduce the thickness of one device by thinning the light source, like the vending machine, it can make further use of the merit by installing a light source (video display) with a pixel control function. Can do.

  Traffic advertisements include posters and signboards in public spaces, internal posters and screens such as trains and buses, and advertisements on the body. In particular, posters and billboards are of a box type using a fluorescent lamp as a backlight, and the box itself can be made thinner and lighter by replacing it with an organic EL.

  In addition, by thinning the box for hanging signboards, dust and dirt can be prevented from being accumulated, and bird damage caused by birds can be prevented.

[Built-in lighting for interior, furniture and building materials]
In terms of architecture, a combination of floors, walls, ceilings, etc. and lighting is called “architectural lighting”. Typical examples of “architectural lighting” include cornice lighting, troffer lighting, cove lighting, light ceiling, and louver ceiling, depending on the method. These require lighting sources to be built into the ceiling, walls and floors, extinguish their presence and signs as lighting, and the building materials themselves to emit light.

  Light sources using organic EL elements are the most suitable light sources for “architecture lighting” due to their thinness, lightness, color adjustment, and design variability, and can be applied to interiors, furniture, and fixtures. It is. Conventionally, such architectural lighting, which has been used only in stores and museums, can be extended to ordinary houses by developing organic EL light sources, and new demand can be found.

  In commercial facilities, organic EL light sources are used in semi-underground stores, arcade ceilings, etc., and by changing the brightness and color temperature of illumination, it is possible to construct an optimal commercial space that is not affected by the weather or day and night.

  Examples of interior / furniture / furniture include desks and chairs, storage of cupboards / shoeboxes / lockers, vanities, altars, bed lights, footlights, handrails, doors, shoji screens, shojis, etc. It is not limited to that.

  On the other hand, transparent / opaque can be switched by using a transparent electrode for the organic EL light source and turning it off / emitting light. As a result, it can be used as any window, door, curtain, blind, and partition.

[Automotive lighting, luminous display]
For automobiles, organic EL elements can be used for external lighting fixtures and light emitting display bodies, in-vehicle lighting fixtures and light emitting display bodies, and the like. The former is a front (sub-classification) headlamp, auxiliary light, vehicle width light, fog lamp, direction indicator light, etc., and the rear is a rear combination lamp as stop lamp, vehicle width light, back light, direction indicator light, and There are license plate lights. In particular, by forming a single rear combination lamp using an organic EL element and attaching it to the rear part, it is possible to reduce the space for the rear lamp and widen the trunk room. In addition, when the visibility is poor due to rain or fog, the visibility of the vehicle can be increased by widening the area of the vehicle width lights and stop lamps. On the other hand, the visibility from the side surface can be enhanced by causing the wheel to emit light with the organic EL element. Furthermore, the entire body can be made of organic EL elements to emit light, and new ideas can be incorporated into the body color and design.

  Examples of the latter in-vehicle lighting fixtures and light-emitting displays include indoor lights, map lights, boarding lights at the bottom of doors, meter displays, car navigation displays, warning lights, and the like. In particular, taking advantage of the transparency of the organic EL element, a sunroof can be used during the daytime and light can be emitted during the nighttime to provide a room light with a gentle surface light source. For taxis, etc., a lighting system consisting of organic EL elements is pasted on the back of the front seat, creating a handy lighting system that is easy for customers to use without hindering driver driving and sacrificing indoor space. Can be built.

〔Public transport〕
The characteristics of the organic EL of the present invention can be utilized in lighting and display bodies in vehicles in public transportation such as trains, subways, buses, airplanes, and ships.

  Although many lighting fixtures are installed in aircraft, among the cabin lighting, cargo cabin lighting, cockpit lighting, etc. mounted inside the aircraft, the benefits of organic EL lighting are fully demonstrated, especially for cabin indirect lighting. Is done.

  Fluorescent lamps and light bulbs are used for room lighting, but these use indirect lighting reflected on the side of the ceiling, which gives the room a calm atmosphere and breaks into glass in the event of a trouble. The device is designed to prevent debris from falling on the audience seats.

  If an organic EL light source is used, it is easy to make indirect illumination because of its thinness, and even if it is directly illuminated, there is no risk of cracking and scattering of fragments, and it is possible to create a calm atmosphere with diffuse light.

  In addition, even in consideration of the importance of power consumption and weight reduction for aircraft, a light-weight organic EL light source with low power consumption is preferable. These benefits not only illuminate the customer, but are also demonstrated in the lighting inside the baggage storage, and can contribute to the reduction of leftovers.

  Display and lighting to guide customers can also be used at facilities such as stations, bus stops, and airports attached to public transportation. In addition, at night or at an outdoor bus stop, a person waiting for the bus can be detected to brighten the lighting, thereby contributing to crime prevention.

[Light source for OA equipment]
Examples of light sources for office automation equipment include facsimiles, copying machines, scanners, printers, and multi-function machines equipped with reading sensors.

  The reading sensor is divided into a contact type sensor (CIS) combined with an equal magnification optical system and a reduction type sensor (CCD linear) combined with a reduction optical system.

  The definition of CIS varies depending on the manufacturer. When the sensor, rod lens array, and LED base are modularized, the module is called CIS, or the modularized module is called CISM (contact image sensor module). The sensor chip is sometimes called CIS. For these light sources, LEDs, xenon, CCFL lamps, LDs and the like are used.

  There is a demand for further miniaturization and low-voltage driving as an OA device, and the feature that the organic EL has no thickness and can be driven with a low calorific value and low voltage can meet these demands. .

[Industrial inspection system]
In the past, manufacturing companies used a lot of man-hours and manpower for the visual inspection process, but this is automated by using a photographed image to determine the shortage. The image of the object captured by the CCD camera is converted into a digital signal, and various arithmetic processes are performed to extract features such as the area, length, number, and position of the object. The one that outputs the result of the determination is that a light source is required to capture the image. Such an inspection system is also used for package, shape size inspection, micro component inspection, and the like.

  Illumination light sources used for image sensors include fluorescent lamps, LEDs, and halogens. Among them, a planar and uniform light is required as a backlight for illuminating a transparent container or a lead frame from the background.

  In addition, the detection content of the light source varies depending on the article to be inspected. For example, light for illuminating the front surface in the width direction of the sheet with linearly uniform light is necessary for detecting the contamination of the sheet.

  By adopting an organic EL light source in this field, for example, in the bottling process, it is possible to illuminate all 360 degrees around the bottle and illuminate and shoot at once, enabling inspection in a short time Become. Moreover, the space taken by the light source itself in the inspection equipment can be greatly reduced. Further, since the surface light source is used, it is possible to avoid a detection error due to difficulty in determining a captured image due to light reflection.

[Light source for agricultural products]
The plant factory is “an annual plant production system using high technology such as environmental control and automation”. A technology that automatically produces crops by controlling the plant cultivation environment with a computer, without being affected by the weather, and without the need for manpower. Considering the world's population growth and environmental issues in the future, the introduction of high technology in agriculture will require so-called agricultural industrialization that leads to stable food production. Recently, LED and LD have been increasingly used as light sources for plant cultivation. Light sources such as high-pressure sodium lamps that are often used in the past have poor spectral balance between red light and blue light, and a large amount of heat radiation increases the air conditioning load and requires a sufficient distance from the plant. In addition, there is a drawback that the facility becomes larger.

  Since the organic EL light source has no light source thickness, many shelves can be installed, and since the calorific value is small, it is highly efficient and can increase the amount of cultivation by bringing it close to the plant.

  Also, taking advantage of space-saving in ordinary households, you can create a kitchen garden in a small indoor space such as a kitchen, changing the concept of a kitchen garden that was possible only in outdoor spaces such as gardens, verandas, and rooftops. It allows people to enjoy widely.

[Evacuation lighting]
The emergency lighting equipment stipulated in the Fire Service Law and Building Standard Law is a guide light that indicates the exit and route for evacuation in the event of a building fire, and an emergency light that ensures the brightness of the evacuation route and ensures quick evacuation. There is.

  Signals, guide lights, emergency lights, etc. used for FA / consumer use are premised on being easy to see, but the enlargement for that is unbalanced with the building depending on the installation location, and it is pointed out by architects and designers There were many things. As countermeasures, measures are taken to make the display a practicable graph at a glance and to increase the attractive effect with a light source. Conventionally, a fluorescent lamp is often used as a light source of a guide lamp, but recently, a guide lamp using an LED has also come out.

  By using an organic EL light source for these guide lights, there is no reduction in brightness due to brightness spots and angular characteristics, visibility can be improved, and low power consumption and thinness make it easy to install without special work. Compared to conventional fluorescent lamp types, there is no need for replacement, and maintenance can be facilitated. In addition, since there is little heat generation, there is little color burn on the light emitting surface. Therefore, it can be installed in many places such as floors of evacuation routes, stairs handrails, fire doors, etc. to improve safety. In addition, there is no problem of mercury, which is currently regarded as a problem with fluorescent lamps, it is difficult to break, and it has excellent safety. Furthermore, it can be said that it is a light source that can enhance the attractive effect without impairing the beauty of the space-saving thin design.

[Lighting for shooting]
Halogen, tungsten, strobe light, fluorescent light, etc. are used as light sources used in photo studios, studios, and lighting photo boxes. Applying these light sources directly to the subject to add a strong shadow, or diffuse light to create soft light with little shadow, a combination of two types of light from various angles. Is made. In order to diffuse light, there are methods such as sandwiching a diffuser between a light source and a subject, or using reflected light applied to another surface (reflective plate or the like).

  The organic EL light source is diffused light, and light corresponding to the latter can be emitted without using a diffuser. In that case, the space between the light source and the diffuser required by the existing light source becomes unnecessary, and the light that has been adjusted with a fine angle by adjusting the direction of the light with a reflex plate etc. is flexible There is an advantage that it can be implemented by bending the type of organic EL itself.

  A color rendering property may be required for a light source used for photographing. If the difference in the color appearance when viewed with sunlight is large, the color rendering is poor, and if the difference is small, the color rendering is evaluated as good. Fluorescent lamps used in general households are not preferable for photographing because of their wavelength characteristics, and the portions that are exposed to light tend to be green. The color of skin, makeup, hair, kimono, jewelry, etc. is often required to be reflected in its own color, and color rendering is one of the important factors for light. An organic EL light source is excellent in color rendering, and is preferable for photographing that requires color fidelity as described above. This feature is also used in places where it is desired to faithfully evaluate colors such as printing and dyeing.

  By placing a surface light source, such as an organic EL light source, on the ceiling of the studio, children and pets can freely play indoors when shooting children and pets, etc., and free and natural expressions can be moved without the hassle of moving light sources Can shoot with natural colors.

〔Home appliances〕
Household appliances are often equipped with light sources for ease of viewing details, ease of work, and design. For example, sewing machines, microwave ovens, dishwashers / dryers, refrigerators, AV equipment, etc. have traditionally been equipped with light sources, but newer models have a light source because they are left behind in the horizontal model. It came to be able to. In many cases, incandescent bulbs and LEDs are attached to existing ones. In the future, we will install lighting at the tip of the vacuum cleaner to check the cleaning status of shadow parts such as furniture, install a light source of specific wavelength light on the shaver, and check the shaving status, etc. Development is possible.

  Such home appliances are required to be light and small as a whole and have a large storage space, and the light source part is required to be able to illuminate the whole without taking up as much space as possible. The thin surface light source of organic EL can fully meet the demand.

[Amusement facilities]
By arranging lighting using organic EL under the ice of the skating rink, it is possible to produce an effect different from the spotlight from above. Organic EL is particularly advantageous because of its low emission temperature. It is also possible to detect the position of the skater and emit light according to the movement of the skater. Combination effects with spotlights and light emission linked to the rhythm of music are also effective for show-ups.

  In the planetarium, instead of the conventional projection from the bottom, a system in which fine pixels of organic EL are arranged on the entire dome and the dome itself emits stars is possible, and a planetarium without a projector can be realized.

[Illumination lighting]
In general, the term “illumination” generally refers to illumination of trees, but in recent years there have been many cases of transition to decoration of objects such as houses, gates, and fences from the viewpoint of environmental protection. Yes. The mainstream of this is the use of a large number of point light sources, decorated in a line shape, and it is thought that the appearance of LEDs will further expand.

  By using organic EL lighting in this field, what was previously expressed only by connecting point light sources, it is possible to use leaf-shaped lighting or wrap around trees for illumination of the same tree. Light up the whole tree, or conversely, connect it like a point light source as a standard surface module, and use it as a cocktail palette to shine in various colors to project characters and pictures as a whole, further enhancing the lighting effect by lighting It becomes possible.

[Lighting for belongings and clothes]
Reflective products that protect the safety of pedestrians by reflecting the light from the headlights attached to their belongings, shoes, and clothes for the purpose of making it easier to be recognized by cars and motorcycles during night walking and exercise. Sheet etc.) are sold and used.

  In the case of the glass bead type, fine glass beads are present on the surface, and the incoming light is retroreflected in the direction of the light source by the role of this lens. It seems to shine strongly when I return. The prism type also has the same function but a different lens structure. The glass bead type and the prism type feature that the glass bead type has a high reflection effect on light from an oblique direction, and the prism type reflects light from the front than the glass bead type, but from an oblique direction. The light may have a relatively low reflection effect. In addition, the material and the bonding method can be selected depending on the location to be pasted. In any case, in order to make pedestrians aware of light, it is necessary to be exposed to light. It was necessary to devise such as pasting.

  By using an organic EL light source for these alternatives, the driver can be made to recognize the pedestrian before the headlight hits the area, and safety can be ensured. In addition, the light source can be made light and thin with respect to other light sources, and the effect can be improved while maintaining the merit of the seal. These can be used not only for humans but also for pet clothes. In addition, it is possible to generate electricity by walking to emit light from clothes, etc., with an organic EL with low power consumption. In particular, the present invention can be applied to clothing for specifying a person, and can be used for early protection of a deaf person, for example. By making the wet suit for diving emit light, there is a possibility of confirming the location of the diver and protecting himself from the trap. Of course, it can also be used for stage costumes and wedding dresses at shows.

[Communication light source]
Luminescent bodies using organic EL elements can be effectively used in “visible light tags” that send simple messages and information using visible light. That is, by emitting a signal due to blinking for an extremely short time, a large amount of information can be sent to the receiving side.

  Even if the illuminant emits a signal, since it is extremely short time, it is recognized as simple illumination in human vision. Lighting installed at each location, such as roads, stores, exhibition halls, hotels, and amusement parks, can send information signals specific to each location and provide necessary information to the receiver. In the case of organic EL, a single light emitter provides a plurality of different information by incorporating a plurality of light emitting dopants having different wavelengths into one light emitter and generating different signals for different wavelengths. You can also. Also in this case, an organic EL element having a stable emission wavelength and color tone is superior.

  Unlike providing information by voice, radio waves, infrared light, etc., the “visible light tag” can be incorporated together as a lighting facility, so there is no need for complicated additional installation work.

[Medical light source]
The use of organic EL elements for endoscopes that currently use halogen lamps and for lighting for abdominal surgery in which wires are inserted for surgery contributes to miniaturization, weight reduction, and application expansion. In particular, it is expected to be applicable to endoscope capsules (drinking endoscopes) used for in-vivo examinations and treatments that have attracted attention in recent years.

[Others]
Furthermore, a light-emitting body incorporating the organic EL element of the present invention can easily select a color tone, does not flicker like a fluorescent lamp, and has a stable color tone with low power consumption. Japanese Patent Application Laid-Open No. 2001-269105 As a pest control device as shown in JP-A-2001-286373, as a mirror illumination as shown in JP-A-2001-286373, as a bathroom lighting system as shown in JP-A-2003-28895, as JP-A-2004-321074 As an artificial light source for plant growth shown in Japanese Laid-Open Patent Publication No. 2004-354232, a light-sensitive agent as shown in Japanese Laid-Open Patent Publication No. 2004-358063 is used as a light emitter of a water pollution measuring apparatus as shown in Japanese Laid-Open Patent Publication No. 2004-354232. It is useful as a medical surgical light as disclosed in Japanese Patent Application Laid-Open No. 2005-322602.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented. The specific structures of the compounds used below are summarized at the end of the examples.

  Note that the emission maximum wavelengths of BD-1 to BD-5 described below are all below 480 nm, the emission maximum wavelength of GD-1 is in the range of 500 nm to less than 580 nm, and the emission maximum wavelength of RD-1 Was in the region of 580 nm or more.

Example 1
<< Production of organic EL element >>
[Production of Organic EL Element 1]
As a positive electrode, after patterning a support substrate in which an ITO (indium tin oxide) film having a thickness of 110 nm is formed on a glass substrate having a thickness of 30 mm × 30 mm and a thickness of 0.7 mm, this ITO transparent electrode is attached to the transparent substrate. The support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then this transparent support substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

  Each of the crucibles for vapor deposition in the vacuum vapor deposition apparatus was filled with an optimum amount of the constituent material of each layer for manufacturing each element. The evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.

Next, after reducing the degree of vacuum to 1 × 10 ⁻⁴ Pa, the deposition crucible containing m-MTDATA was energized and heated, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second. A 20 nm hole injection layer was provided. Next, the evaporation crucible containing α-NPD was heated and evaporated in the same manner to provide a hole transport layer having a thickness of 30 nm.

  Next, the compound BD-1, the compound RD-1, and the compound M-1 are adjusted so that the content of the compound BD-1 becomes a uniform concentration of 20% in the entire region of the light emitting layer, and the compound RD-1 has a front chromaticity. Is co-evaporated at a deposition rate of 0.1 nm / second at an optimum concentration so that x = 0.45 ± 0.03 and y = 0.42 ± 0.03 (CIE 1931), and phosphorescence emission with a thickness of 70 nm A layer was formed. In the preparation of all the organic EL elements 1 to 8 below, the concentration of the compound RD-1 does not depend on the thickness of the light emitting layer, and the front chromaticity is x = 0.45 ± 0.03, y = 0.42 ± 0.03 (CIE1931) was adjusted as appropriate.

  Thereafter, Compound M-2 was deposited to a thickness of 30 nm to form an electron transport layer, and potassium fluoride (KF) was further formed to a thickness of 2 nm. Further, aluminum was deposited with a thickness of 110 nm to form a cathode.

  Subsequently, the non-light-emitting surface of the element was covered with a glass case, and an organic EL element 1 having the configuration shown in FIGS. 1 and 2 was produced.

  FIG. 1 shows a schematic diagram of an organic EL element. The organic EL element 101 is covered with a glass cover 102. The sealing operation with the glass cover was performed in a glove box (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere. FIG. 2 shows a cross-sectional view of the organic EL element. In FIG. 2, 105 denotes a cathode, 106 denotes an organic EL layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

[Production of Organic EL Element 2]
It carried out similarly to preparation of the said organic EL element 1, and formed to the positive hole transport layer.

  Next, Compound BD-1, Compound RD-1, and Compound M-1 are combined so that Compound BD-1 has a concentration of 67% to 36% linearly with respect to the film thickness direction from the anode side. The vapor deposition ratio was sequentially changed, and co-deposition was performed at a deposition rate of 0.1 nm / second to a thickness of 25 nm.

  Next, the compound BD-1, the compound RD-1, and the compound M-1 are combined with the compound BD so that the blue phosphorescent compound BD-1 has a concentration of 36% to 19% linearly with respect to the film thickness from the anode side. The vapor deposition ratio of −1 was sequentially changed and co-evaporated to a thickness of 45 nm at a vapor deposition rate of 0.1 nm / second to form a light emitting layer having a thickness of 70 nm as a whole.

  Thereafter, in the same manner as in the organic EL element 1, an electron transport layer, a KF layer, and an aluminum layer (cathode) were formed.

  Next, in the same manner as in the organic EL element 1, the non-light-emitting surface of the organic EL element was covered with a glass case to produce an organic EL element 2.

[Production of Organic EL Element 3]
In the production of the organic EL element 1, an organic EL element 3 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 4]
In the production of the organic EL element 2, an organic EL element 4 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 5]
In the production of the organic EL element 1, an organic EL element 5 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 6]
In the production of the organic EL element 2, an organic EL element 6 was produced in the same manner except that instead of the compound BD-1, the exemplified compound D-82 was used as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 7]
In the production of the organic EL element 1, an organic EL element 7 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 8]
In the production of the organic EL element 2, an organic EL element 8 was produced in the same manner except that the example compound D-85 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 9]
In the production of the organic EL element 1, an organic EL element 9 was produced in the same manner except that the exemplified compound D-86 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 10]
In the production of the organic EL element 2, the organic EL element 10 was produced in the same manner except that the exemplified compound D-86 was used in place of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 11]
In the production of the organic EL device 1, an organic EL device 11 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 12]
In the production of the organic EL element 2, the organic EL element 12 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 13]
In the production of the organic EL element 1, an organic EL element 13 was produced in the same manner except that instead of the compound BD-1, the exemplified compound D-13 was used as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 14]
In the production of the organic EL element 2, an organic EL element 14 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 15]
In the production of the organic EL element 1, an organic EL element 15 was produced in the same manner except that instead of the compound BD-1, the exemplified compound D-15 was used as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 16]
In the production of the organic EL element 2, an organic EL element 16 was produced in the same manner except that instead of the compound BD-1, the exemplified compound D-15 was used as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 17]
In the production of the organic EL element 1, an organic EL element 17 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 18]
In the production of the organic EL element 2, an organic EL element 18 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 19]
In the production of the organic EL element 1, an organic EL element 19 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 20]
In the production of the organic EL element 2, an organic EL element 20 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 21]
In the production of the organic EL element 1, an organic EL element 21 was produced in the same manner except that the exemplified compound D-31 was used in place of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 22]
In the production of the organic EL element 2, an organic EL element 22 was produced in the same manner except that the compound BD-1 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 23]
In the production of the organic EL element 1, an organic EL element 23 was produced in the same manner except that the exemplified compound D-37 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 24]
In the production of the organic EL element 2, an organic EL element 24 was produced in the same manner except that the exemplified compound D-37 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 25]
In the production of the organic EL element 1, an organic EL element 25 was produced in the same manner except that the exemplified compound D-43 was used in place of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 26]
In the production of the organic EL element 2, an organic EL element 26 was produced in the same manner except that the exemplified compound D-43 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 27]
In the production of the organic EL element 1, an organic EL element 27 was produced in the same manner except that the example compound D-52 was used instead of the compound BD-1 as the blue phosphorescent compound used in the light emitting layer.

[Production of Organic EL Element 28]
In the production of the organic EL element 2, an organic EL element 28 was produced in the same manner except that instead of the compound BD-1, the exemplified compound D-52 was used as the blue phosphorescent compound used in the light emitting layer.

<< Evaluation of organic EL elements >>
(Measurement of power efficiency)
Using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing Co., Ltd.), the front luminance and luminance angle dependency of each organic EL element were measured, and the power efficiency at the front luminance of 1000 cd / m ² was obtained. Is shown in Table 1. Table 1 shows organic EL elements having no concentration distribution (organic EL elements 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27) are expressed as relative values with the efficiency as 100. The higher the power efficiency, the higher the efficiency and the better.

[Measurement of chromaticity variation with respect to driving voltage]
A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing Co., Ltd.) was used to determine the chromaticity fluctuation range when the drive voltage was changed. Chromaticity variation range, when obtained by modulating the intensity by changing the driving voltage was determined by the following equation (1) as the fluctuation maximum distance ΔE of CIE 1931 x, y values in the front luminance ^{500cd / m 2 ~2000cd / m 2} . Table 1 shows the relative value of the difference when ΔE of organic EL elements having no concentration distribution (organic EL elements 1, 3, 5, 7, 9) is set to 100 for combinations of the presence or absence of concentration distribution of each blue phosphorescent compound. Is shown in Table 1. ΔE indicates that the smaller the value, the smaller the chromaticity variation and the better the chromaticity stability with respect to the drive voltage.

表１に示されるように、本発明の分子構造を有する青燐光発光化合物を含有する有機ＥＬ素子は、発光層内で濃度分布を付与させることにより電力効率、駆動電圧に対する色度安定性が共に改善されている。一方、本発明外の分子構造の青燐光発光化合物を含有する有機ＥＬ素子２は、発光層内に濃度分布を有することにより電力効率、駆動電圧に対する色度安定性がむしろ劣化している。Formula (1)
ΔE = (Δx ² + Δy ² ) ^1/2

As shown in Table 1, the organic EL device containing the blue phosphorescent compound having the molecular structure of the present invention has both power efficiency and chromaticity stability with respect to driving voltage by providing a concentration distribution in the light emitting layer. It has been improved. On the other hand, the organic EL element 2 containing a blue phosphorescent compound having a molecular structure outside of the present invention has rather deteriorated power efficiency and chromaticity stability with respect to driving voltage due to the concentration distribution in the light emitting layer.

  In addition, in the blue phosphorescent compound having the molecular structure of the present invention, it is better to use a compound having a maximum electron occupation level of less than 5.3 eV of the blue phosphorescent compound when the compound has a concentration distribution. It can be seen that the improvement range is large.

Example 2
<< Production of organic EL element >>
[Production of Organic EL Element 29]
The hole transport layer was provided in the same manner as in the method for producing the organic EL element 1 described in Example 1.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was varied by changing the concentration so that Exemplified Compound D-28 was linearly 50% to 36% of the film thickness from the anode side. Co-evaporation was performed at a rate of 0.1 nm / second to a thickness of 25 nm.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was varied by changing the concentration so that Exemplified Compound D-28 was linearly 36% to 19% of the film thickness from the anode side. Co-evaporation was performed so that the thickness was 45 nm at a speed of 0.1 nm / second, and a light emitting layer having a thickness of 70 nm was formed as a whole. In addition, the vapor deposition amount of the compound RD-1 and the compound M-1 was made the same as the preparation conditions of the organic EL element 1 described in Example 1.

  Thereafter, in the same manner as in the production of the organic EL element 1 described in Example 1, an electron transport layer, a KF layer, and an aluminum layer (cathode) were formed.

  Next, in the same manner as in the production of the organic EL element 1 described in Example 1, the non-light emitting surface of the element was covered with a glass case, and an organic EL element 29 was produced.

[Production of Organic EL Element 30]
The hole transport layer was provided in the same manner as in the method for producing the organic EL element 1 described in Example 1.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was varied by changing the concentration so that Exemplified Compound D-28 was linearly 84% to 36% with respect to the film thickness from the anode side. Co-evaporation was performed at a rate of 0.1 nm / second to a thickness of 25 nm.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was varied by changing the concentration so that Exemplified Compound D-28 was linearly 36% to 19% of the film thickness from the anode side. Co-evaporation was performed so that the thickness was 45 nm at a speed of 0.1 nm / second, and a light emitting layer having a thickness of 70 nm was formed as a whole. In addition, the vapor deposition amount of the compound RD-1 and the compound M-1 was made the same as the preparation conditions of the organic EL element 1 described in Example 1.

  Thereafter, in the same manner as in the production of the organic EL element 1 described in Example 1, an electron transport layer, a KF layer, and an aluminum layer (cathode) were formed.

  Next, in the same manner as the production of the organic EL element 1 described in Example 1, the non-light-emitting surface of the element was covered with a glass case, and the organic EL element 30 was produced.

[Production of Organic EL Element 31]
The hole transport layer was provided in the same manner as in the method for producing the organic EL element 1 described in Example 1.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was changed by changing the concentration so that Exemplified Compound D-28 was linearly 100% to 36% with respect to the film thickness from the anode side. Co-evaporation was performed at a rate of 0.1 nm / second to a thickness of 25 nm.

  Next, the concentration of Exemplified Compound D-28, Compound RD-1, and Compound M-1 was varied by changing the concentration so that Exemplified Compound D-28 was linearly 36% to 19% of the film thickness from the anode side. Co-evaporation was performed so that the thickness was 45 nm at a speed of 0.1 nm / second, and a light emitting layer having a thickness of 70 nm was formed as a whole. In addition, the vapor deposition amount of the compound RD-1 and the compound M-1 was made the same as the preparation conditions of the organic EL element 1 described in Example 1.

  Thereafter, in the same manner as in the production of the organic EL element 1 described in Example 1, an electron transport layer, a KF layer, and an aluminum layer were formed.

  Next, in the same manner as in the production of the organic EL element 1 described in Example 1, the non-light-emitting surface of the element was covered with a glass case to produce an organic EL element 31.

  Next, in the same manner as in Example 1, the chromaticity fluctuation range with respect to the power efficiency and the driving voltage was measured.

  The obtained results are shown in Table 2. In addition, the numerical value of Table 2 is shown by the relative value which sets the power efficiency of the organic EL element 3 and the chromaticity fluctuation range as 100.

表２に示されるように、本発明の好ましい態様である発光層の陽極側端部の青発光材料含有量が６０％以上１００％未満の有機ＥＬ素子は、６０％より低い素子に比較して、電力効率が高く、色度変動も小さいことが判る。また、発光層の陽極側端部の青発光材料含有量が１００％になると電力効率はむしろ濃度分布を有しない素子と比較しても低下しており、また、色度の変動も大きくなり、好ましくないことが分かる。

As shown in Table 2, the organic EL device having a blue light emitting material content of 60% or more and less than 100% in the anode side end of the light emitting layer, which is a preferred embodiment of the present invention, is compared with a device having a lower content than 60%. It can be seen that the power efficiency is high and the chromaticity variation is small. In addition, when the content of the blue light emitting material at the anode side end of the light emitting layer becomes 100%, the power efficiency is rather lowered as compared with an element having no concentration distribution, and the variation in chromaticity also increases. It turns out that it is not preferable.

Example 3
<< Production of organic EL element >>
[Production of Organic EL Element 32]
The hole transport layer was provided in the same manner as in the method for producing the organic EL element 1 described in Example 1.

  Next, the concentration of Exemplified Compound D-28, Compound GD-1, Compound RD-1, and Compound M-1 was such that Illustrative Compound D-28 was linear from 67% to 36% with respect to the film thickness from the anode side. , And co-deposited to a thickness of 25 nm at a deposition rate of 0.1 nm / second.

  Next, the concentration of Exemplified Compound D-28, Compound GD-1, Compound RD-1, and Compound M-1 was such that Exemplified Compound D-28 was linearly 36% to 19% with respect to the film thickness from the anode side. Was changed and co-evaporated to a thickness of 45 nm at a deposition rate of 0.1 nm / second to form a light emitting layer having a thickness of 70 nm as a whole. The concentrations of Compound GD-1 and Compound RD-1 do not depend on the film thickness of the light emitting layer, and the front chromaticity is x = 0.45 ± 0.03, y = 0.42 ± 0.03 ( Conditions such as CIE1931) were appropriately adjusted.

  Thereafter, in the same manner as in the production of the organic EL element 1 described in Example 1, an electron transport layer, a KF layer, and an aluminum layer (cathode) were formed.

  Next, in the same manner as the production of the organic EL element 1 described in Example 1, the non-light-emitting surface of the element was covered with a glass case, and the organic EL element 32 was produced.

  Next, the chromaticity variation width with respect to the power efficiency and the driving voltage was measured in the same manner as in Example 1, and the obtained results are shown in Table 3. In Table 4, the power efficiency and the chromaticity variation range of the organic EL element 4 are shown as relative values, each being 100.

表３に記載の結果より明らかなように、有機ＥＬ素子４に対し、緑燐光発光化合物を加えた有機ＥＬ素子３２は、電力効率、駆動電圧に対する色度安定性（ΔＥ相対値）が更に改善された良好な結果を示している。

As is clear from the results shown in Table 3, the organic EL element 32 in which the green phosphorescent compound is added to the organic EL element 4 further improves the power efficiency and the chromaticity stability (ΔE relative value) with respect to the driving voltage. Shows good results.

Example 4
<< Production of organic EL element >>
[Production of Organic EL Element 33]
The hole transport layer was provided in the same manner as in the method for manufacturing the organic EL element 32 described in Example 3.

  Next, the exemplary compound D-28, the compound GD-1, the compound RD-1, and the compound M-1 were thickened at a deposition rate of 0.1 nm / second so that the exemplary compound D-28 had a uniform concentration of 67%. Co-deposited to a thickness of 10 nm.

  Next, the exemplary compound D-28, the compound GD-1, the compound RD-1, and the compound M-1 were thickened at a deposition rate of 0.1 nm / second so that the exemplary compound D-28 had a uniform concentration of 36%. Co-deposited to a thickness of 20 nm.

  Next, the exemplary compound D-28, the compound GD-1, the compound RD-1, and the compound M-1 were thickened at a deposition rate of 0.1 nm / second so that the exemplary compound D-28 had a uniform concentration of 19%. Co-evaporation was performed to a thickness of 40 nm to form a light emitting layer having a thickness of 70 nm as a whole. The vapor deposition conditions for the compound GD-1, the compound RD-1, and the compound M-1 were the same as those for the display element 32 described in Example 3.

  Thereafter, an electron transport layer, a KF layer, and an aluminum layer (cathode) were formed in the same manner as in the production of the organic EL element 32 described in Example 3.

  Next, in the same manner as the production of the organic EL element 32 described in Example 3, the non-light-emitting surface of the element was covered with a glass case, and the organic EL element 33 was produced.

  Next, in the same manner as in the method described in Example 1, the chromaticity variation width with respect to the power efficiency and the driving voltage was measured.

  In addition, in order to estimate the durability of the organic EL element, the front chromaticity after storage for 300 hours in an 85 ° C. environment as a forced deterioration condition was measured, and the fluctuation width ΔE (refer to Table 4) with the front chromaticity before storage. Was expressed in the same manner as in the above formula (1).

  Table 4 shows the results obtained as described above. In addition, the power efficiency of the organic EL element 32, the chromaticity stability with respect to the driving voltage (shown as “ΔE relative value versus driving voltage” in Table 4), and the fluctuation range ΔE of the front chromaticity before and after storage at 85 ° C., respectively. The relative value is 100.

表４に記載した結果より明らかなように、本発明の好ましい態様である発光層の青燐光発光化合物の濃度を連続的に変化させた有機ＥＬ素子３２は、青燐光発光化合物の濃度を階段状に変化させた有機ＥＬ素子３３と比較し、電力効率、駆動電圧に対する色度安定性は同等であるものの、素子を８５℃で保存した前後での色度変動が小さく、総合的に優れた性能を有していることが分かる。

As is clear from the results shown in Table 4, the organic EL element 32 in which the concentration of the blue phosphorescent compound in the light emitting layer, which is a preferred embodiment of the present invention, was continuously changed, the concentration of the blue phosphorescent compound was changed stepwise. Compared with the organic EL element 33 changed to, the chromaticity stability with respect to power efficiency and driving voltage is equivalent, but the chromaticity fluctuation before and after storing the element at 85 ° C. is small, and overall excellent performance It can be seen that

Example 5
<< Production of organic EL element >>
[Production of Organic EL Element 34]
In the production of the organic EL element 4 described in Example 1, an organic EL element 34 was produced in the same manner except that the compound M-3 was used instead of the compound M-1 as a material used for the light emitting layer.

[Production of Organic EL Element 35]
In the production of the organic EL element 16, an organic EL element 35 was produced in the same manner except that the compound M-4 was used instead of the compound M-3 as the material used for the light emitting layer.

[Production of Organic EL Element 36]
In the production of the organic EL element 16, an organic EL element 36 was produced in the same manner except that the compound M-5 was used instead of the compound M-3 as a material used for the light emitting layer.

  Next, in the same manner as in the method described in Example 1, the chromaticity variation width with respect to the power efficiency and the driving voltage was measured.

Further, continuous driving was performed at an initial luminance of 8000 cd / m ² until the luminance decreased by 50%, and the variation width ΔE of front chromaticity before and after continuous driving (in Table 5, “ΔE relative value vs. continuous driving” Display) was determined according to the equation (1).

  Table 5 shows the results obtained as described above. In Table 5, the power efficiency of the organic EL element 4, the chromaticity stability with respect to the driving voltage (in Table 5, “ΔE relative value vs. driving voltage”) and the chromaticity stability during continuous driving (Table In FIG. 5, “ΔE relative value vs. continuous driving”) is indicated as a relative value with 100 as each.

表５に記載の結果より明らかなように、本発明の好ましいホスト化合物を用いた有機ＥＬ素子４及び３４は、有機ＥＬ素子３５及び３６に比較し優れた性能を示していることが分かる。

As is clear from the results shown in Table 5, it can be seen that the organic EL elements 4 and 34 using the preferred host compound of the present invention show superior performance compared to the organic EL elements 35 and 36.

  Below, in Examples 1-5, the structure of the compound used for preparation of each organic EL element is shown.

  The organic electroluminescence device of the present invention is excellent in power efficiency and excellent in stability in chromaticity versus driving voltage, versus driving time and device storage, and is suitably used as a display device, a display, and various light-emitting light sources. it can.

DESCRIPTION OF SYMBOLS 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with a transparent electrode 108 Nitrogen gas 109 Water catching agent

Claims (6)

At least one phosphorescent dopant A having at least one emission maximum in a short wavelength region of 480 nm or less and at least one phosphorescent dopant B having an emission maximum in a long wavelength region of 580 nm or more between opposed electrodes. The phosphorescent light-emitting dopant A has a light-emitting layer contained in the same layer, and the phosphorescent light-emitting dopant A is at least one compound selected from the compounds represented by the following general formulas (A) to (C). It is contained at a high concentration on the anode side of the light emitting layer, is contained with a concentration distribution so as to become a low concentration toward the cathode side, and the content of the phosphorescent dopant A at the end on the anode side is An organic electroluminescence device characterized by being 60% by mass or more and less than 100% by mass of the total mass of the anode side end of the light emitting layer.

[Wherein, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represents a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group or a halogen atom, and A1 represents an aromatic ring. Alternatively, it represents a residue necessary for forming an aromatic heterocyclic ring, and M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]

[Wherein, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb, Rc, Rb ₁ and Rc ₁ each represent a hydrogen atom, and A1 represents an aromatic ring or an aromatic heterocyclic ring. Represents the residue necessary to form, M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]

[In the formula, Ra represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, Rb and Rc each represent a hydrogen atom or an alkyl group, and A1 forms an aromatic ring or an aromatic heterocyclic ring. And M represents Ir or Pt. X ₁ and X ₂ each represent a carbon atom, a nitrogen atom, or an oxygen atom, and L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . m1 represents an integer of 1, 2 or 3, m2 represents an integer of 0, 1 or 2, and m1 + m2 is 2 or 3. ]   The organic electroluminescence device according to claim 1, wherein the phosphorescent dopant A has a highest electron occupation level shallower than 5.3 eV.   The light emitting layer containing the phosphorescent dopants A and B contains at least one phosphorescent dopant C having an emission maximum in a wavelength region of 500 nm or more and less than 580 nm. Organic electroluminescence device. 4. The organic electroluminescence according to claim 1, wherein the light emitting layer containing the phosphorescent dopants A and B contains a host compound represented by the following general formula (a). 5. element.

[Wherein, X represents NR ′, O, S, CR′R ″ or SiR′R ″. R ′ and R ″ each represent a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. Ar represents an aromatic ring. N represents an integer of 0 to 8.] 5. The concentration of at least one phosphorescent dopant B having an emission maximum in a long wavelength region of 580 nm or longer is a constant concentration in the film thickness direction of the light emitting layer. The organic electroluminescent element of description. Lighting device characterized by use of an organic electroluminescent device according to any one of claims 1 to 5.

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