JP5261745B2 - Organic electroluminescence element, display device, liquid crystal display device, and illumination device - Google Patents

Description

  The present invention relates to an organic electroluminescence element, a display device, a liquid crystal display device, and a lighting device.

  As a light-emitting electronic display device, there is an electroluminescence display (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.

  An organic EL 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 (excitons) are generated by injecting electrons and holes into the light-emitting layer and recombining them. The device emits light by utilizing the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoints of space saving and portability.

  Another major feature of the organic EL element is that it is a surface light source, unlike main light sources that have been conventionally used in practice, such as light-emitting diodes and cold-cathode tubes. Applications that can make effective use of this characteristic include illumination light sources and backlights for various displays. In particular, it can be suitably used as a backlight of a liquid crystal full-color display whose demand has been increasing in recent years.

  When used as a backlight of such a full color display, it is used as a white light source. In order to obtain white light with an organic EL element, a method of obtaining a white color by adjusting a light emitting material in one element, a multicolored light emitting pixel, for example, blue, green, and red are separately applied to emit light simultaneously. There are a method of obtaining a white color by mixing colors, a method of 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), and the like.

  However, in view of various demands required for backlights, such as low cost, high productivity, and a simple driving method, a method of adjusting the light emitting material in one organic EL element and obtaining white color by mixing is effective for this application. In recent years, research and development has been actively promoted.

  Describing in more detail about this method, in order to obtain white light, a method of obtaining a white color by mixing two light emitting materials having complementary colors in an organic EL element, for example, a blue light emitting material and a yellow light emitting material, There is a method to obtain a white color by mixing light emitting materials of three colors of blue, green, and red, but light emission of three colors of blue, green, and red from the viewpoint of color reproducibility and reducing light loss in the color filter. A method of mixing colors using materials is preferred. For example, it has been reported that white organic EL elements can be obtained by doping high-efficiency phosphors of blue, green, and red as light emitting materials (see, for example, Patent Documents 1 and 2).

  However, even when using light emitting materials of three colors, blue, green and red, the color reproducibility is not yet satisfactory in combination with a color filter. This is because the emission spectrum characteristics of the organic EL element cannot be sufficiently adjusted from the viewpoint of color reproducibility with respect to the transmission spectrum of a color filter developed mainly for liquid crystal displays.

  For example, Patent Document 1 describes the emission maximum wavelengths of blue, green, and red, but does not describe the shape of the emission spectrum, which is an important factor that affects color reproducibility. There is no description about a spectrum also about the said patent document 2. FIG.

  Furthermore, although there is an example of a white organic EL element, there is no description regarding the spectrum shape (see, for example, Patent Documents 3 to 5). Furthermore, in the spectrum, since the maximum wavelength of the emission band corresponding to green is less than 500 nm (for example, see Patent Document 4), preferable color reproducibility (especially for the hues of the green region and the blue region) is not obtained. Further, in the spectrum, since the absorption maximum of the emission band corresponding to green is larger than 550 nm (for example, see Non-Patent Document 1), preferable color reproducibility (especially for the hues of the green region and the red region) has not been obtained. .

  In addition, since a brighter organic EL element can be obtained, development of phosphorescent light emitting materials has been promoted in recent years (for example, see Non-Patent Documents 2 and 3 and Patent Document 5). This is because the emission from the conventional phosphor is emission from the excited singlet, and the generation ratio of the singlet exciton and triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. On the other hand, in the case of a phosphorescent material using light emission from an excited triplet, the upper limit of internal quantum efficiency is 100 due to the exciton generation ratio and internal conversion from singlet excitons to triplet excitons. Therefore, in principle, the luminous efficiency can be up to four times that of fluorescent materials.

  However, in the case of phosphorescence, the emission spectrum tends to be broader due to the vibration band structure. This is not preferable in order to obtain good color reproducibility in combination with a color filter, and when using a phosphorescent material, it is necessary to pay attention to its emission spectrum waveform, and waveform adjustment technology A combination with is also required.

As a white organic EL element using a phosphorescent material, the maximum wavelength of the emission band corresponding to green is larger than 550 nm (for example, see Non-Patent Document 4). It is difficult to obtain the hue of the red region), and the maximum wavelength of the red emission band and the minimum emission intensity between the green region and the blue region are disclosed (for example, see Non-Patent Document 5). Somehow, the preferred color reproducibility is not obtained.
JP-A-6-207170 JP 2004-235168 A JP-A-8-78163 JP-A-8-96959 US Pat. No. 6,097,147 Y. Kawamura et al. , Journal of Applied Physics, 92 (2002), p. 87 M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) B. W. D'Andrade et al. , Adv. Mater. 14 (2002), p. 147 Y. Tung et al. SID 2004 DIGEST, p. 48

  An object of the present invention is to provide a white light-emitting organic EL element having high luminance and good color reproducibility in combination with a color filter, and a display device and an illumination device using the same.

  The above object of the present invention has been achieved by the following constitutions 1-12.

1. In an organic electroluminescence device having an organic layer including at least an anode, a cathode, and a plurality of light emitting layers between the anode and the cathode on a support substrate,
Yes emission spectrum, 440Nm～480nm (blue region) in emission maximum A, 500nm~540nm (green region) emission maximum B, and emission maximum C to 600Nm～640nm (red region), as the emission maximum by each different emitters The light emission minimum intensity a between the light emission maximum A and the light emission maximum B and the light emission minimum intensity b between the light emission maximum B and the light emission maximum C each have a low light emission intensity among the adjacent light emission maximums. The emission minimum intensity is 60% or less, and at least one of the emission minimum intensity a and the emission minimum intensity b is an intensity of 45% or less of the adjacent emission maximum intensity. Organic electroluminescence device.

2. 2. The organic electroluminescence device according to 1, wherein the host compound contained in the light emitting layer is represented by the following general formula (1) .
In the formula, Z ₁ represents an aromatic heterocyclic ring which may have a substituent, Z ₂ represents an aromatic heterocyclic ring or an aromatic hydrocarbon ring which may have a substituent, and Z ₃ Represents a divalent linking group or a simple bond. R ₁₀₁ represents a hydrogen atom or a substituent.
However, 4,4′-N, N′-dicarbazole biphenyl and polyvinyl carbazole are excluded.

3. 3. The organic electroluminescence device according to 2 above, wherein the compound represented by the general formula (1) is contained in a layer adjacent to the light emitting layer .

4). 4. The organic electroluminescence device according to 3 above, wherein the adjacent layer of the light emitting layer is a hole blocking layer .

5. 5. The organic electroluminescence device according to any one of 1 to 4, wherein a non-light emitting intermediate layer is provided between the plurality of light emitting layers .

6). 6. The organic electroluminescence device as described in 5 above , wherein the adjacent layer of the light emitting layer is the non-light emitting intermediate layer .

7). 7. A display device comprising the organic electroluminescence device according to any one of 1 to 6 as a backlight, and at least a color filter as one of its constituent members.

8). It has the organic electroluminescent element of any one of said 1-6 as a backlight, The liquid crystal display device characterized by the above-mentioned.

9. It has an organic electroluminescent element of any one of said 1-6 , The illuminating device characterized by the above-mentioned.

  According to the present invention, it is possible to provide a white light-emitting organic EL element having high luminance and good color reproducibility in combination with a color filter, and a display device and an illumination device using the same.

It is an emission spectrum of an organic EL element. It is an emission spectrum of an organic EL element. It is an emission spectrum of an organic EL element. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device. It is a schematic diagram which shows an example of the laminated constitution of a barrier film, and its density profile. It is the schematic which shows an example of the atmospheric pressure plasma discharge processing apparatus which processes a base material.

Explanation of symbols

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 trapping agent 201 Barrier film 202 Base material 203 Low density layer 204 Medium density layer 205 High density layer 230 Plasma discharge processing apparatus 231 Plasma discharge treatment vessel 235 Roll rotating electrode 236 Square tube type fixed electrode group 240 Electric field applying means 250 Gas supply means 251 Gas generating means 253 Exhaust port 260 Electrode temperature adjusting means 261 Piping 266 Nip roll 267 Guide roll 268, 269 Partition plate F Base material P liquid pump

In the organic EL device of the present invention, a white backlight having high luminance and excellent color reproducibility in combination with a color filter is provided by adopting the configuration defined in any one of 1 to 9 above. It is possible to provide an organic EL element that can be used, a display device using the organic EL element, and a lighting device.

  Hereinafter, details of each component according to the present invention will be sequentially described.

<< Organic EL element >>
The organic EL element of the present invention will be described.

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

The organic EL device of the present invention is a white light emitting device, but preferably the chromaticity in the CIE 1931 color system is X = 0.33 ± 0.07, Y = 0.33 ± 0.07, more preferably The chromaticity in the CIE1931 color system at 1000 cd / m ² is X = 0.33 ± 0.07, Y = 0.33 ± 0. It is preferable that it exists in the area | region of 07.

  The emission spectrum of the organic EL device of the present invention is that the emission spectrum is emission maximum A at 440 nm to 480 nm (blue region), emission maximum B at 500 nm to 540 nm (green region), and emission at 600 nm to 640 nm (red region). The light emission minimum intensity a between the light emission maximum A and the light emission maximum B, and the light emission minimum intensity b between the light emission maximum B and the light emission maximum C are respectively adjacent light emission maximums. The emission maximum intensity showing a low emission intensity is 60% or less, and at least one of the emission minimum intensity a or the emission minimum intensity b is an intensity of 45% or less of the adjacent emission maximum intensity. .

  If the emission maximum wavelength is out of the above range, it is generally difficult to obtain good color reproducibility when combined with a color filter composed of BGR three-color pixels, and it is particularly difficult to achieve both luminance and color reproducibility. In addition, when the light emission minimum intensity is larger than the above value, the color purity of the three primary colors of blue, green, and red is low in the combination with the color filter, and it is difficult to ensure a sufficient color reproduction range. This is because the transmitted light spectrum of each color of the color filter is generally broad, and the color purity of each primary color is not necessarily high. In the present invention, any one of at least one emission minimum intensity selected between the blue area and the green area or between the green area and the red area is 45% or less of the emission maximum intensity. Although it is adjusted, color separation between the blue region and the green region or between the red region and the green region can be improved, and a characteristic color reproduction can be obtained. More preferably, the light emission minimum intensity in the three regions of the blue region, the green region, and the red region is more preferably 45% or less of the light emission maximum intensity.

  In the present invention, the emission minimum wavelength between the blue region and the green region is 470 nm to 510 nm, the emission minimum wavelength between the green region and the red region is 570 nm to 600 nm, or a light emitting panel by combining color filters, When forming the display device, it is preferable that the spectral transmission characteristics of the color filter and the minimum emission wavelength are adjusted so as to satisfy the following relationship.

λ _BG −20 ≦ λ ₁ ≦ λ _BG +10
λ _GR −20 ≦ λ ₂ ≦ λ _GR +10
Here, λ ₁ (nm) is an emission minimum wavelength between the blue region and the green region, λ ₂ (nm) is an emission minimum wavelength between the green region and the red region, and λ _BG (nm) is a wavelength of 450 nm to 550 nm. The wavelength at which the product of the transmittance of the color filter blue pixel and the transmittance of the green pixel in the range becomes the maximum, λ _GR (nm) is the transmittance of the color filter green pixel and the transmittance of the red pixel in the wavelength range of 550 nm to 630 nm. The wavelength at which the product is maximum.

  By reducing the light emission in the overlapping region of the transmitted light spectrum of each color filter of the color filter, the purity of each primary color can be increased and the color reproduction range can be expanded.

  In order to obtain the emission spectrum of the organic EL device of the present invention, a method for adjusting an optimal waveform by combining arbitrary light emitting materials, incorporating a material having absorption in the region of the light emission minimum wavelength into the organic EL device, and using a filter effect A method for adjusting the light emission waveform coming out of the organic EL element, a method for adjusting the light emission waveform by a filter effect by incorporating a material having absorption in the region of the light emission minimum wavelength outside the organic EL element, light reflection in the organic EL element A method for adjusting the waveform coming out of the organic EL element by intensifying or weakening light in an arbitrary wavelength region by the optical interference effect, and the principle of the diffraction grating in the organic EL element and / or on the surface of the organic EL element There is a method of adjusting the waveform coming out of the organic EL element by intensifying or weakening light in an arbitrary wavelength region.

  In the present invention, since the waveform can be adjusted while suppressing optical loss, a method for adjusting to an optimal waveform by combining arbitrary light emitting materials, an arbitrary wavelength due to an optical interference effect using light reflection in the organic EL element A method of adjusting the waveform that is emitted outside the organic EL element by intensifying the light in the region, the organic EL element by intensifying the light in an arbitrary wavelength region by the diffraction grating principle in the organic EL element and / or on the surface of the organic EL element A method of adjusting the waveform coming out is preferable.

  In the present invention, any light emitting material as will be described later can be used. However, since materials having a light emission efficiency and a preferable light emission waveform are limited, the light interference effect using the light reflection in the organic EL element is arbitrary. The method of adjusting the waveform coming out of the organic EL element by intensifying the light in the wavelength range and / or the light in any wavelength range in the organic EL element and / or the surface of the organic EL element by the diffraction grating principle It is particularly preferable to incorporate the method of adjusting the waveform coming out of the organic EL element by strengthening into the organic EL element as an adjustment method.

  A method for adjusting the waveform based on the diffraction grating principle will be described later in the section of light extraction and light collection technology.

  Regarding the method of adjusting the waveform that emerges outside the organic EL element by intensifying the light in an arbitrary wavelength range by the light interference effect using the light reflection in the organic EL element, each layer and each member in the organic EL element Although it is not particularly limited as long as the waveform can be adjusted using reflection / interference generated at the interface, in the present invention, the interface between the light emitting layer, the cathode, and the organic layer, and the interface between the light emitting layer, the support substrate, and the anode are used. Reflection and interference between them can be preferably used.

In the present invention, in order to utilize this effect, the film thickness d of the organic layer sandwiched between the anode and the cathode particularly with respect to the light emission maximum wavelength λmax (nm) of either the blue region or the green region. It is preferable that ₁ and d ₂ (nm) satisfy the relationship of the following formula (1) and the following formula (2).

Formula (1)
(2m + 1) λmax / 4-10 ≦ d ₁ ≦ (2m + 1) λmax / 4 + 10
Formula (2)
(M + 1) λmax / 2−10 ≦ d ₂ ≦ (m + 1) λmax / 2 + 10
Here, d ₁ (nm) is an optical distance between the cathode side end of the light emitting region of the blue region or the green region to which λmax (nm) belongs and the cathode surface, and d ₂ (nm) is λmax (nm The optical distance between the cathode side end of the light emitting region of the blue region or the green region to which the substrate) belongs and the anode-substrate interface. m is 0 or a positive integer. When the blue or green light emitting region is divided into a plurality of regions or layers, d ₂ is defined by the optical distance between the cathode side end of the region or layer having the highest luminance and the cathode surface.

  The light emitting layer that is a constituent layer of the organic EL element of the present invention is not particularly limited as long as the light emission spectrum of the organic EL element has the above shape, but the maximum emission wavelength is in the blue region. It is preferable to have at least three light emitting layers of a blue light emitting layer, a green light emitting layer in the green region, and a red light emitting layer in the red region.

  The light-emitting layer according to the organic EL element of the present invention will be described in detail in the layer configuration of the organic EL element described later.

  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.

(1) Anode / light emitting layer unit / electron transport layer / cathode (2) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (4) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode (5) anode / anode buffer layer / hole transport layer / light emission Layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer unit may be a single light emitting layer or a plurality of light emitting layers. Furthermore, when it has a several light emitting layer, it is preferable to have a nonluminous intermediate | middle layer between each light emitting layer.

<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 configuration of the light emitting layer according to the present invention is not particularly limited as long as the light emission maximum wavelength satisfies the above requirements, but the light emission maximum wavelength is a blue light emitting layer in the blue region, and a green light emission in the green region. Preferably, the light emitting layer has at least three light emitting layers of the red light emitting layer in the red region.

  In addition, when the number of light emitting layers is more than four, there may be a plurality of layers having the same emission spectrum or emission maximum wavelength.

  Hereinafter, in the present invention, a layer having an emission maximum wavelength of 440 nm to 480 nm is referred to as a blue light emitting layer, a layer having a wavelength in the range of 500 nm to 540 nm is referred to as a green light emitting layer, and a layer in the range of 600 nm to 640 nm is referred to as a red light emitting layer.

  There is no restriction | limiting in particular as a lamination order of a light emitting layer, It is preferable to have a nonluminous intermediate | middle layer between each light emitting layer. In the present invention, it is preferable that at least one blue light emitting layer is provided at a position closest to the anode in all the light emitting layers. When four or more light-emitting layers are provided, for example, blue / green / red / blue, blue / green / red / blue / green, blue / green / red / blue / green / red from the order close to the anode. In order to improve luminance stability, it is preferable to sequentially stack blue, green, and red.

  The total film thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film, preventing unnecessary application of high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferable to adjust in the range of 2 nm to 5 μm, more preferably in the range of 2 nm to 200 nm, and particularly preferably in the range of 10 nm to 20 nm.

  The film thickness of each light emitting layer is preferably adjusted to a range of 2 nm to 100 nm, and more preferably adjusted to a range of 2 nm to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

  For the production of the light-emitting layer, a light-emitting dopant or a host compound, which will be described later, is formed and formed by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink-jet method. it can.

  In addition, a plurality of light emitting compounds may be mixed in each light emitting layer within a range in which the above spectral shape requirement is maintained. For example, a blue light emitting layer may be used by mixing a blue light emitting compound having a maximum wavelength of 440 nm to 480 nm and a green light emitting compound having a maximum wavelength of 500 nm to 540 nm.

  Next, a host compound and a light emitting dopant (also referred to as a light emitting dopant compound) included in the light emitting layer will be described.

(Host compound)
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, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary luminescent colors can be obtained.

  As the host compound according to the present invention, a compound represented by the following general formula (1) is preferably used. Moreover, the said compound is preferably used also for the adjacent layer (for example, hole-blocking layer etc.) of a light emitting layer.

  An organic EL device comprising a compound represented by the following general formula (1) in a light emitting layer or a layer adjacent to the light emitting layer and using the phosphorescent emitter according to the present invention for the light emitting layer has high luminous efficiency. A device with high brightness can be obtained.

In the formula, Z ₁ represents an aromatic heterocyclic ring which may have a substituent, Z ₂ represents an aromatic heterocyclic ring or an aromatic hydrocarbon ring which may have a substituent, and Z ₃ Represents a divalent linking group or a simple bond. R ₁₀₁ represents a hydrogen atom or a substituent.

In the general formula (1), examples of the aromatic heterocycle represented by Z ₁ and Z ₂ include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a benzimidazole ring, Diazole 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, carboline ring And a ring in which the carbon atom of the hydrocarbon ring is further substituted with a nitrogen atom. Furthermore, the aromatic heterocyclic ring may have a substituent represented by R ₁₀₁ described later.

In the general formula (1), examples of the aromatic hydrocarbon ring represented by Z ₂ include 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, pyranthrene ring, anthraanthrene ring and the like. Furthermore, the aromatic hydrocarbon ring may have a substituent represented by R ₁₀₁ described later.

In the general formula (1), examples of the substituent represented by R ₁₀₁ include an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group). Group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.) Etc.), aryl groups (eg phenyl group, naphthyl group etc.), aromatic heterocyclic groups (eg 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.), heterocyclic group (eg Pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cyclo An alkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), an aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), an 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 methyl Xycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, Aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2 -Pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexane) A silcarbonyl group, an octylcarbonyl group, a 2-ethylhexylcarbonyl group, a dodecylcarbonyl group, a phenylcarbonyl group, a naphthylcarbonyl group, a pyridylcarbonyl group, etc.), an acyloxy group (for example, an acetyloxy group, an ethylcarbonyloxy group, a butylcarbonyloxy group) Octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonyl) Amino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylca Carbonylamino 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, cyclohexylureido group, octylureido group, Dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfide group, etc.) Sulfonyl 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, ethyl group) Amino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridyla Group), halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon groups (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), And cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

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

  Preferred substituents are an alkyl group, a cycloalkyl group, a fluorinated hydrocarbon group, an aryl group, and an aromatic heterocyclic group.

  As the divalent linking group, in addition to hydrocarbon groups such as alkylene, alkenylene, alkynylene, and arylene, those containing a hetero atom may be used, and a thiophene-2,5-diyl group, pyrazine-2, It may be a divalent linking group derived from a compound having an aromatic heterocycle (also called a heteroaromatic compound) such as a 3-diyl group, or may be a chalcogen atom such as oxygen or sulfur. . Further, it may be a group such as an alkylimino group, a dialkylsilanediyl group, or a diarylgermandiyl group that connects and connects heteroatoms.

  A mere bond is a bond that directly bonds the connecting substituents together.

In the present invention, Z _{1 in the} general formula (1) is preferably a 6-membered ring. Thereby, luminous efficiency can be made higher. Furthermore, the lifetime can be further increased.

In the present invention, it is preferable that the Z ₂ in the general formula (1) is a 6-membered ring. Thereby, luminous efficiency can be made higher. Furthermore, the lifetime can be further increased.

Furthermore, it is preferable that Z ₁ and Z _{2 in} the general formula (1) are both 6-membered rings because the luminous efficiency can be further increased. Furthermore, it is preferable because the lifetime can be further increased.

  Hereinafter, although the specific example of a compound represented by General formula (1) based on this invention is shown, this invention is not limited to these.

  The light emitting host used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (deposition polymerization property). Light emitting host).

  As the known host compound, a compound having a hole transporting ability and an electron transporting ability, preventing an increase in the wavelength of light emission, and having a high Tg (glass transition temperature) is preferable.

  Specific examples of known host compounds include compounds described in the following documents. 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, the light emitting maximum wavelength has at least three light emitting layers of a blue light emitting layer in the range of 440 to 480 nm, a green light emitting layer in the range of 500 to 540 nm, and a red light emitting layer in the range of 600 to 640 nm. Preferably, 50% by mass or more of the host compounds of at least two layers of the three layers each have a phosphorescence emission energy of 2.9 eV or more and a Tg (glass transition point) of 90 ° C. or more. A compound is preferable, More preferably, it is a compound of 100 degreeC or more. Among these, from the viewpoint of improving the storage stability of organic EL elements (also referred to as durability improvement) and reducing the uneven distribution of the compound at the light emitting layer interface, the molecular structures of the compounds are preferably the same.

  Here, the reason why it is preferable that the host compounds have the same physicochemical characteristics or the same molecular structure will be described in detail in the non-light emitting intermediate layer described later.

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

  By using a host compound having the same physical characteristics as described above, and more preferably by using a host compound having the same molecular structure, the entire organic compound layer (also referred to as an organic layer) of the organic EL element is used. In addition, it is possible to obtain a uniform film property and to adjust the phosphorescence emission energy of the host compound to be 2.9 eV or more. In particular, when a phosphorescent dopant is used, the energy transfer to the dopant is efficient. And higher brightness can be obtained.

(Phosphorescent energy)
The phosphorescence emission energy according to the present invention will be described.

  The phosphorescence emission energy according to the present invention is the peak energy of the 0-0 band of phosphorescence emission obtained when measuring the photoluminescence of a deposited film of 100 nm on a support substrate (which may be simply a substrate) with a host compound. say.

<< Measurement Method of 0-0 Band of Phosphorescence >>
First, a method for measuring a phosphorescence spectrum will be described.

  The luminescent host compound to be measured is dissolved in a well-deoxygenated mixed solvent of ethanol / methanol = 4/1 (volume / volume), put into a phosphorescence measurement cell, and then irradiated with excitation light at a liquid nitrogen temperature of 77K. Then, an emission spectrum at 100 ms is measured after the excitation light irradiation. Since phosphorescence has a longer emission lifetime than fluorescence, it can be considered that light remaining after 100 ms is almost phosphorescence. For compounds with a phosphorescence lifetime shorter than 100 ms, measurement may be performed with a short delay time. However, if the delay time is set so short that it cannot be distinguished from fluorescence, phosphorescence and fluorescence cannot be separated. Therefore, it is necessary to select a delay time that can be separated.

  In addition, for a compound that cannot be dissolved in the solvent system, any solvent that can dissolve the compound may be used (substantially, the solvent effect of the phosphorescence wavelength is negligible in the above measurement method).

  Next, the 0-0 band is determined. In the present invention, the emission maximum wavelength that appears on the shortest wavelength side in the phosphorescence spectrum chart obtained by the above measurement method is defined as the 0-0 band.

  Since the phosphorescence spectrum usually has a low intensity, when it is enlarged, it may be difficult to distinguish between noise and peak. In such a case, the emission spectrum during excitation light irradiation (for convenience, this is referred to as a steady light spectrum) is expanded, and the emission spectrum 100 ms after excitation light irradiation (for convenience, this is referred to as a phosphorescence spectrum) is superimposed. It can be determined by reading the peak wavelength of the phosphorescence spectrum from the stationary light spectrum portion derived from the light spectrum.

  Further, by performing a smoothing process on the phosphorescence spectrum, it is possible to separate the noise and the peak and read the peak wavelength. As the smoothing process, a smoothing method of Savitzky & Golay can be applied.

(Luminescent dopant)
The light emitting dopant according to the present invention will be described.

As the light-emitting dopant according to the present invention, a fluorescent compound or a phosphorescent emitter (also referred to as a phosphorescent compound or a phosphorescent compound) can be used, but a viewpoint of obtaining an organic EL element with higher luminous efficiency. From the above, the light-emitting dopant used in the light-emitting layer and the light-emitting unit of the organic EL device of the present invention (sometimes simply referred to as a light-emitting material) contains the above-mentioned host compound and simultaneously contains a phosphorescent light-emitting material. It is preferable.

  It is preferable to have a phosphorescent body having a light emission maximum in each of the green region and the blue region. Moreover, it is preferable to have a phosphorescent light emitter having a light emission maximum in the red region.

(Phosphorescent light emitter)
The phosphorescent emitter according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is Although defined as a compound of 0.01 or more at 25 ° C., a preferred phosphorescence quantum yield is 0.1 or more.

  The phosphorescence quantum yield can be measured by 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 phosphorescence quantum yield (0.01 or more) in any solvent. Just do it.

  There are two types of light emission of phosphorescent emitters in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent emitter. The energy transfer type that emits light from the phosphorescent emitter by moving to the other, the phosphorescent emitter becomes a carrier trap, carrier recombination occurs on the phosphorescent emitter, and from the phosphorescent emitter Although it is a carrier trap type in which light emission is obtained, in any case, it is a condition that the excited state energy of the phosphorescent emitter is lower than the excited state energy of the host compound.

  The phosphorescent emitter can be appropriately selected from known ones used for the light emitting layer of the organic EL element.

  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.

  Although the specific example of the compound used as a phosphorescent body is shown below, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

(Fluorescent light emitter (also called fluorescent dopant))
Typical examples of fluorescent emitters (fluorescent dopants) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Examples thereof include dyes, perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

  Conventionally known dopants can also be used in the present invention. For example, International Publication No. 00/70655 pamphlet, JP-A Nos. 2002-280178, 2001-181616, 2002-280179, 2001 181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002. No. 324679, International Publication No. 02/15645, JP 2002-332291 A, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572, JP 2 No. 02-117978, No. 2002-338588, No. 2002-170684, No. 2002-352960, Pamphlet of International Publication No. 01/93642, JP 2002-50483, No. 2002-1000047. No. 2002-173684, No. 2002-359082, No. 2002-17584, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808. JP-A 2003-7471, JP-T 2002-525833, JP-A 2003-31366, JP-A 2002-226495, JP-A 2002-234894, JP-A 2002-2335076, JP-A 2002-24175 Gazette, 2001-319779, 2001-319780, 2002-62824, 2002-1000047, 2002-203679, 2002-343572, 2002-203678. A gazette etc. are mentioned.

<Non-light emitting intermediate layer>
A non-light emitting intermediate layer (also referred to as an undoped region or the like) used in the present invention will be described.

  The non-light emitting intermediate layer is a layer provided between the light emitting layers in the case of having a plurality of light emitting layers.

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

  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) In the case where the physicochemical characteristics such as photoluminescence energy and glass transition point are the same, or the molecular structure of the host compound is the same, etc.) The barrier is reduced, and the effect of easily maintaining the injection balance of holes and electrons even when the voltage (current) is changed can be obtained. Furthermore, the host compound contained in each light emitting layer in the undoped light emitting layer is a major problem in the production of a conventional organic EL device by using a host material having the same physical characteristics or the same molecular structure. The complexity of manufacturing the organic EL element can also be eliminated.

  In addition, in an organic EL element having blue, green, and red light emitting layers, when a phosphorescent light emitter is used for each light emitting material, the excited triplet energy of the blue phosphorescent light emitter is the largest. The light emitting layer and the non-light emitting intermediate layer may contain a host material having an excited triplet energy larger than that of the blue phosphorescent emitter as a common host material.

  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 between injection and transport of holes and electrons, 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.

  On the other hand, 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. As mentioned.

  In the present invention, it is preferable that the light emitting maximum wavelength has at least three light emitting layers of a blue light emitting layer in the blue region, a green light emitting layer in the green region, and a red light emitting layer in the red region, The light emitting layer closest to the anode is preferably a blue light emitting layer. In this embodiment, between the blue light emitting layer and the light emitting layer other than blue next to the anode, the ionization potential (the ionization potential measurement method is applied to the blocking layer) with respect to the host compound contained in the blue light emitting layer. It is the same as the method for measuring the ionization potential of such a compound.) From the viewpoint of improving the luminance of the organic EL device of the present invention, it is preferable to have a non-emissive layer containing 50% by mass or more of a compound having a larger 0.2 eV or more. .

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists 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. May be.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The 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 is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, 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 concerning this invention as needed.

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

  The ionization potential is defined by the energy required to emit an electron at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.

  (1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA The ionization potential can be obtained as a value obtained by rounding off the second decimal place of the value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G *. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

  (2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  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 thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 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 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-4-30 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type ( MTDATA) and the like.

  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-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

  The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. 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 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use a hole transport layer having such a high p property because an organic EL element with lower power consumption can be produced.

《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.

  In the case of a single-layer electron transport layer and a plurality of layers, as an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the cathode side with respect to the light emitting layer, electrons injected from the cathode As long as it has a function of transmitting to the light emitting layer, and any of known materials can be selected and used as the material. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiols Examples include pyran 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.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use such an electron transport layer having a high n property because an organic EL element with lower power consumption can be produced.

《Support base》
The support substrate (hereinafter also referred to as a substrate, a substrate, a substrate, a support, etc.) according to the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent or opaque. It may be. In the case where light is extracted from the support base side, the support base is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support base 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 polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, 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 in accordance with JIS K 7129-1992 is 0.01 g / m ^2. It is preferably a barrier film of day · atm or less, and further, the oxygen permeability measured by a method according to JIS K 7126-1992 is 10 ⁻³ g / m ² / day or less, water vapor permeability Is preferably a high barrier film of 10 ⁻³ g / m ² / day or less, and the water vapor permeability and oxygen permeability are both 10 ⁻⁵ g / m ² / day or less, Further preferred.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry 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 organic material layers. 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.

<Method for forming barrier film>
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 weighting. A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

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

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  Here, an example of the layer structure of the transparent barrier film used for the support base according to the present invention will be described with reference to FIG. 6, and further, an example of the atmospheric pressure plasma discharge treatment apparatus preferably used for forming the barrier layer will be described with reference to FIG. Will be described.

  FIG. 6 is a schematic diagram illustrating an example of a layer configuration of a barrier film (also referred to as a gas barrier film) and a density profile thereof.

  The barrier film 201 (which may be transparent or opaque) has a configuration in which layers having different densities are stacked on the base material 202. In the present invention, a medium density layer 204 is provided between the low density layer 203 and the high density layer 205, and the medium density layer 204 is also provided on the high density layer 205, and these low density layer and medium density layer are provided. FIG. 6 shows an example in which a unit composed of a high-density layer and a medium-density layer is one unit and two units are stacked. At this time, the density distribution in each density layer is uniform, and the density change between adjacent layers is stepped. In FIG. 6, the medium density layer 204 is shown as one layer, but a configuration of two or more layers may be adopted as necessary.

  FIG. 7 is a schematic view showing an example of an atmospheric pressure plasma discharge treatment apparatus for treating a substrate.

  The atmospheric pressure plasma discharge processing apparatus is an apparatus having at least a plasma discharge processing apparatus 230, an electric field applying means 240 having two power supplies, a gas supply means 250, and an electrode temperature adjusting means 260.

  FIG. 7 shows an interval (discharge space) 232 between the roll rotating electrode (first electrode) 235 and the square tube type fixed electrode group (second electrode) 236 (each electrode is also a square tube type fixed electrode 236). Thus, the substrate F is subjected to plasma discharge treatment to form a thin film. In FIG. 7, a pair of rectangular tube type fixed electrode group (second electrode) 236 and roll rotating electrode (first electrode) 235 form one electric field. Is formed. FIG. 7 shows a configuration example including a total of five units having such a configuration. In each unit, the types of raw materials to be supplied, the output voltage, and the like are controlled arbitrarily and independently. A mold barrier film (also referred to as a transparent gas barrier layer) can be formed continuously.

In the discharge space (between the counter electrodes) 232 between the roll rotating electrode (first electrode) 235 and the square tube type fixed electrode group (second electrode) 236, the roll rotating electrode (first electrode) 235 has a first power source. The first high-frequency electric field having the frequency ω ₁ , the electric field intensity V ₁ , and the current I ₁ from the frequency 241, and the frequency ω ₂ from each second power source 242 corresponding to the square tube fixed electrode group (second electrode) 236, respectively. A second high frequency electric field of electric field strength V ₂ and current I ₂ is applied.

  A first filter 243 is installed between the roll rotation electrode (first electrode) 235 and the first power source 241. The first filter 243 easily passes a current from the first power source 241 to the first electrode. In addition, the current from the second power source 242 is grounded so that the current from the second power source 242 to the first power source is difficult to pass.

  In addition, a second filter 244 is installed between the square tube type fixed electrode group (second electrode) 236 and the second power source 242, and the second filter 244 is connected to the second electrode from the second power source 242. It is designed so that the current from the first power source 241 is grounded and the current from the first power source 241 to the second power source is difficult to pass.

The roll rotating electrode 235 may be the second electrode, and the square tube fixed electrode group 236 may be the first electrode. In any case, the first power source is connected to the first electrode, and the second power source is connected to the second electrode. The first power supply preferably applies a higher frequency electric field strength (V ₁ > V ₂ ) than the second power supply. Further, the frequency has the ability to satisfy ω ₁ <ω ₂ .

The current is preferably I ₁ <I ₂ . Current I ₁ of the first high-frequency electric field is preferably ^{0.3mA / cm 2 ~20mA / cm 2} , more preferably at ^{1.0mA / cm 2 ~20mA / cm 2} . The current I ₂ of the second high-frequency electric field is preferably ^{10mA / cm 2 ~100mA / cm 2} , more preferably ^{20mA / cm 2 ~100mA / cm 2} .

  The gas G generated by the gas generator 251 of the gas supply means 250 is introduced into the plasma discharge processing container 231 from the air supply port while controlling the flow rate.

  The base material F is unwound from the original winding (not shown), or is transported from the previous process, or transported from the previous process, and the air or the like that is entrained by the base material by the nip roll 265 via the guide roll 264 is blocked. , While rotating while being in contact with the roll rotating electrode 235, it is transferred between the rectangular tube fixed electrode group 236 and the roll rotating electrode (first electrode) 235 and the rectangular tube fixed electrode group (second electrode) 236. An electric field is applied from both, and discharge plasma is generated between the counter electrodes (discharge space) 232. The base material F forms a thin film with a gas in a plasma state while being wound while being in contact with the roll rotating electrode 235. The substrate F passes through the nip roll 266 and the guide roll 267, and is taken up by a winder (not shown) or transferred to the next process.

  Discharged treated exhaust gas G ′ is discharged from the exhaust port 253.

  In order to heat or cool the roll rotating electrode (first electrode) 235 and the rectangular tube type fixed electrode group (second electrode) 236 during the thin film formation, a medium whose temperature is adjusted by the electrode temperature adjusting means 260 is used as a liquid feed pump. P is sent to both electrodes via the pipe 261, and the temperature is adjusted from the inside of the electrode. Reference numerals 268 and 269 denote partition plates that partition the plasma discharge processing vessel 231 and the outside.

<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 base 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 preferably has an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻³ g / m ² / day or less. Further, it is more preferable that both the water vapor permeability and the oxygen permeability are 10 ⁻⁵ g / m ² / day or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used. Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, 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.

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

  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), 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, In particular, 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 organic EL element, a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the 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 electrode materials include metals such as Au, and conductive transparent materials such as 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 small 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, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. 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.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, 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 a material for an anode is formed on a suitable support base by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm. To do. Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic EL element materials, is formed thereon.

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

  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 of about 2 V to 40 V with the anode as + and the cathode as-. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<< Light extraction and condensing technology >>
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index of about 1.6 to 2.1), and only about 15 to 20% of light generated in the light emitting layer can be extracted. Is generally said. 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 extracted outside the organic EL element, or the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total internal reflection, 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 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 and preventing total reflection at the interface between the transparent substrate and the air (for example, US Pat. No. 4,77,4435). ), A method of improving the efficiency by providing the substrate with a light condensing property (for example, JP-A-63-314795), a method of forming a reflective surface on the side surface of the organic EL element, etc. No. 220394), a method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Application Laid-Open No. Sho 62-172691), between the substrate and the light emitter. A method of introducing a flat layer having a lower refractive index than the substrate (for example, JP-A-2001-202827), a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (between the substrate and the outside) Method of forming There is 11-283751 JP), and the like.

  In the present invention, these methods can be used in combination with the organic EL 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 a substrate, transparent A method of forming a diffraction grating between any layers of the 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.

  As described above, 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 grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

《Condensing sheet parts》
The organic EL device of the present invention can be processed to provide, for example, a structure on a microlens array on the light extraction side of a support base (substrate), or combined with a so-called condensing sheet, for example in a specific direction Condensing light in the front direction with respect to the light emitting surface can increase the luminance in a specific direction.

  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 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 Limited can be used. As the shape of the prism sheet, for example, a substrate may be formed with a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or the apex angle is rounded and the pitch is changed randomly. Other shapes may be used.

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

<Application>
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 especially as a backlight of a liquid crystal display device combined with a color filter and a light source for illumination.

  When used as a backlight of a display in combination with a color filter, it is preferably used in combination with the light collecting sheet in order to further increase the luminance.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “film thickness ratio (%)”. The structures of the compounds used in the examples are shown below.

Example 1
<< Production of Organic EL Element 1-1 >>
Transparent support with this ITO transparent electrode after patterning on a substrate (also called support base) on which a 120 nm ITO (Indium Tin Oxide) film is formed on a 30 mm × 30 mm, 0.7 mm thick glass substrate as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

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

Next, after reducing the vacuum to 4 × 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 hole injection layer was provided.

  Furthermore, with a mixing ratio shown in Table 1, energization is performed to the evaporation crucible loaded with the above materials so that each layer is formed, and co-evaporation or single evaporation is performed to form a hole transport layer, each light emitting layer, and each intermediate layer. Each layer was deposited.

  Further, the deposition crucible containing BAlq was energized and heated, and deposited on the layer at a deposition rate of 0.1 nm / second to produce a hole blocking layer, and then an electron transport layer was provided in the same manner. .

  Furthermore, aluminum 110nm was vapor-deposited, the cathode was formed, and the organic EL element 1-1 was produced.

<< Production of Organic EL Elements 1-2 to 1-4 >>
Organic EL elements 1-2 to 1-4 were produced in the same manner as the organic EL element 1-1 except that the constituent materials and film thickness of each layer were changed as described in Tables 1 and 2 below.

<< Seal treatment of organic EL element and evaluation of front luminance, chromaticity, emission spectrum >>
Each non-light-emitting surface of the obtained organic EL elements 1-1 to 1-4 was covered with a glass case. 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 into contact with the atmosphere. After making it into an illuminating device as shown in FIG. 4, FIG. 5, the front luminance, chromaticity, and emission spectrum of each organic EL element were evaluated using the spectral radiance meter CS-1000 (made by Konica Minolta Sensing).

Further, all of the organic EL elements 1-1 to 1-4 have a chromaticity in the CIE1931 color system with a 2 ° viewing angle front luminance of 1000 cd / m ² and X = 0.33 ± 0.07, Y = It was within the range of 0.33 ± 0.07.

  Subsequently, the color gamut when the color filter marketed for displays was combined was evaluated. The reproduction range is indicated by a relative value where the area of a triangle connecting the chromaticity points of the transmitted light of each pixel of the color filter BGR is 100 in the combination of the organic EL element 1-1 and the color filter. The larger the value, the wider and better the color reproduction range. These results are shown in Table 3 and FIGS.

  From Table 3, it is clear that the organic EL device having the emission spectrum shape of the present invention has excellent performance in color reproducibility. In the organic EL element 1-4, the emission minimum intensity of both the blue-green region and the green-red region is 60% or less of the emission maximum, but the emission minimum intensity between green and red is 45% or less of the emission maximum. A certain organic EL element 1-3 of the present invention has a wider color gamut.

Example 2
<< Preparation of Organic EL Element 2-1 >>
An organic EL element 2-1 was produced in the same manner as the organic EL element 1-2 of Example 1 except that the constituent materials and film thickness of each layer were changed as described in Tables 4 and 5 below.

<< Seal treatment of organic EL element and evaluation of front luminance, chromaticity, emission spectrum >>
The organic EL element 2-1 was sealed in the same manner as the organic EL element 1-2 produced in Example 1, and the front luminance and color were combined with the organic EL element 1-2 in the same manner as in Example 1. The emission spectrum was evaluated.

  Subsequently, the color reproducibility at the time of combining the color filter marketed for displays was evaluated. The reproduction range is indicated by a relative value where the organic EL element 1-2 is 100. These results are shown in Table 6 and FIG.

  From Table 6, the same material as the organic EL element 1-2 of the comparative example was used, and the organic EL element 2- of the present invention produced by adjusting the film thickness of the organic layer to the formulas (1) and (2) was used. No. 1 clearly shows that the ratio between the light emission minimum intensity and the light emission maximum intensity in the region between blue and green is improved and has excellent performance in the color reproduction range.

Example 3
<Production of white lighting device>
The non-light emitting surfaces of the organic EL elements 1-3 and 2-1 (both of the present invention) obtained in Example 1 were covered with a glass case to obtain an illumination device as shown in FIGS. The illuminating device could be used as a thin illuminating device that emits white light with high luminous efficiency and long emission life. FIG. 4 is a schematic view of the lighting device, and the organic EL element 101 is covered with a glass cover 102. Note that the sealing operation with the glass cover was performed in a glove box under a nitrogen atmosphere without bringing the organic EL element 101 into contact with the air (in a high-purity nitrogen gas atmosphere having a purity of 99.999% or more). FIG. 5 is a cross-sectional view of the lighting device. In FIG. 5, reference numeral 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.

  When the obtained illuminating device was energized, almost white light was obtained, and it was found that the illuminating device could be used.

Claims (9)

In an organic electroluminescence device having an organic layer including at least an anode, a cathode, and a plurality of light emitting layers between the anode and the cathode on a support substrate,
Yes emission spectrum, 440Nm～480nm (blue region) in emission maximum A, 500nm~540nm (green region) emission maximum B, and emission maximum C to 600Nm～640nm (red region), as the emission maximum by each different emitters The light emission minimum intensity a between the light emission maximum A and the light emission maximum B and the light emission minimum intensity b between the light emission maximum B and the light emission maximum C each have a low light emission intensity among the adjacent light emission maximums. The emission minimum intensity is 60% or less, and at least one of the emission minimum intensity a and the emission minimum intensity b is an intensity of 45% or less of the adjacent emission maximum intensity. Organic electroluminescence device. The organic electroluminescence device according to claim 1, wherein the host compound contained in the light emitting layer is represented by the following general formula (1).
In the formula, Z ₁ represents an aromatic heterocyclic ring which may have a substituent, Z ₂ represents an aromatic heterocyclic ring or an aromatic hydrocarbon ring which may have a substituent, and Z ₃ Represents a divalent linking group or a simple bond. R ₁₀₁ represents a hydrogen atom or a substituent.
However, 4,4′-N, N′-dicarbazole biphenyl and polyvinyl carbazole are excluded. The organic electroluminescent element according to claim 2, wherein the compound represented by the general formula (1) is contained in a layer adjacent to the light emitting layer. The organic electroluminescence device according to claim 3, wherein the adjacent layer of the light emitting layer is a hole blocking layer. The organic electroluminescence device according to claim 1, further comprising a non-light emitting intermediate layer between the plurality of light emitting layers. 6. The organic electroluminescent element according to claim 5, wherein the adjacent layer of the light emitting layer is the non-light emitting intermediate layer. A display device comprising the organic electroluminescence element according to claim 1 as a backlight and at least a color filter as one of its constituent members. A liquid crystal display device comprising the organic electroluminescence element according to claim 1 as a backlight. It has an organic electroluminescent element of any one of Claims 1-6 , The illuminating device characterized by the above-mentioned.