JP6136175B2 - White electroluminescence device - Google Patents

Description

  The present invention relates to a white electroluminescence device, and more particularly to a white electroluminescence device excellent in luminous efficiency, luminous lifetime and production stability.

  In recent years, organic electroluminescence elements using organic substances (hereinafter, abbreviated as “organic EL elements” where appropriate) are promising for use as solid light-emitting inexpensive large-area full-color display elements and writing light source arrays. Research and development is actively underway.

  The organic EL element is composed of an organic functional layer (single layer portion or multilayer portion) having a thickness of only about 0.1 μm containing an organic light emitting material between a pair of anode and cathode formed on a film. It is a thin film type all solid state device. When a relatively low voltage of about 2 to 20 V is applied to such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the organic compound layer. It is known that emission is obtained by releasing energy as light when the electrons and holes recombine in the light emitting layer and the energy level returns from the conduction band to the valence band. This technology is expected as a flat display and lighting.

  The recently discovered organic EL element using phosphorescence emission can in principle achieve light emission efficiency of about 4 times compared to that using previous fluorescence emission. Research and development of functional layers and electrodes are conducted all over the world. In particular, as one of the measures to prevent global warming, application to lighting fixtures that occupy much of human energy consumption has begun to be studied. There are many attempts to reduce costs.

  A white light emitting panel for illumination is required to have high efficiency and long life, and in particular, in the life extension, the performance is low with respect to fluorescent lamps and white LEDs. Further, although blue phosphorescent light emitting materials have been found to have high luminous efficiency, no actual material that can be applied and is satisfactory in terms of long life and color purity has not been found. is there.

  Furthermore, in recent years, there has been an active movement to produce a desired white color by combining a plurality of phosphorescent light emitting materials for practical application of a white light emitting panel.

  However, phosphorescent light-emitting materials are known to cause energy transfer between the respective light-emitting materials, and in order to perform desired white light emission, the components of blue light-emitting materials are changed into green light-emitting materials and red light-emitting materials. There is a problem in producing a white light emitting device in which the amount of light emission needs to be greatly increased and the emission color is controlled and the chromaticity is stable.

  As a method of solving these problems, there is a method of using “quantum dots” that are inorganic light emitting materials as light emitting materials. Quantum dots are applicable to the coating process because they are inorganic in addition to a sharp emission spectrum and have good durability and are soluble in various solvents.

  For example, in Patent Document 1, white light emission is achieved by forming quantum dots on the light emission side surface of a light emitting element and supplementing the emission color of the light emitting layer by light emission excited by down-conversion. However, in this method, the light emission lifetime depends on the light emitting layer material, and a sufficiently long lifetime has not been obtained yet.

  On the other hand, in Patent Document 2, white is achieved by combining a plurality of quantum dots. However, the white external quantum yield is as low as about 4%, and there are still problems in practical use.

  In Patent Document 3, a charge transporting material is used as a quantum dot capping material for the purpose of improving luminous efficiency. Although it has been confirmed in this patent that charge recombination is promoted, further improvement in performance is desired.

JP 2006-190682 A International Publication No. 2007/095173 International Publication No. 2009/041595

  The present invention has been made in view of the above problems and circumstances, and its solution is to provide a white electroluminescent device with high luminous efficiency and long life, which is particularly excellent in productivity and continuous production. However, it is to provide a white electroluminescent device that emits white light with stable chromaticity.

  As a result of examining the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor found that the mass ratio of quantum dots emitting in three specific wavelength regions of blue, green, and red in the light-emitting layer and two or more kinds The present inventors have found that the above problems can be solved by specifying the photoluminescence emission quantum yield of the quantum dots of the present invention.

  That is, the said subject which concerns on this invention is solved by the following means.

1. 1. A white electroluminescent device having a reverse layer structure having a light emitting layer sandwiched between an anode and a cathode provided on a support substrate, wherein the light emitting layer is a quantum having a light emission maximum wavelength in a range of 400 to 500 nm. One or more dots (BQD), quantum dots (GYQD) having an emission maximum wavelength in the range of 500 to 580 nm, and quantum dots (ORQD) having an emission maximum wavelength in the range of 580 to 650 nm, respectively The mass ratio of the quantum dots in the light emitting layer satisfies the following formulas (A) and (B), and at least two of the BQD, GYQD, and ORQD have a photoluminescence emission quantum yield of 70% or more. Ah is, furthermore, a white-elect said light emitting layer has a that you containing host compounds represented by the following general formula (1) Luminescence device.

（式中、Ｘは、ＮＲ′、酸素原子、硫黄原子、ＣＲ′Ｒ″、又はＳｉＲ′Ｒ″を表す。ｙ _１ 及びｙ _２ は、各々ＣＲ′又は窒素原子を表す。Ｒ′及びＲ″は、各々水素原子又は置換基を表す。Ａｒ _１ 及びＡｒ _２ は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎは０〜４の整数を表す。） Formula (A) 5.5 ≦ BQD / GYQD ≦ 12.0
Formula (B) 1.0 ≦ GYQD / ORQD ≦ 1.3

(In the formula, X represents NR ′, oxygen atom, sulfur atom, CR′R ″, or SiR′R ″. Y ₁ and y ₂ each represent CR ′ or a nitrogen atom. R ′ and R ″. Each represents a hydrogen atom or a substituent, Ar ₁ and Ar ₂ each represent an aromatic ring, and may be the same or different, and n represents an integer of 0 to 4.)

2 . 2. The white electroluminescent device according to item 1 , wherein the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of the host compound is 459 nm or less.

3 . X in the said General formula (1) is NR ', The white electroluminescent device of Claim 1 or 2 characterized by the above-mentioned.

4 . X in the said General formula (1) is an oxygen atom, The white electroluminescent device as described in any one of Claim 1 to 3 characterized by the above-mentioned.

5 . The white electroluminescence device according to any one of Items 1 to 4, wherein the light emitting layer contains a conductive polymer.

6 . 6. The white electroluminescent device according to any one of items 1 to 5, wherein the quantum dot has an average particle size in the range of 1 to 20 nm.

7 . The quantum dot is composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In ₂ S ₃ , ZnO, CdO, or a mixture thereof. Item 9. The white electroluminescent device according to any one of Items 6 to 6 .

8 . The molecular weight of the host compound, white electroluminescent device according to any one of the first term, which is a range of 500 to 1000 to paragraph 7.

  By the above means of the present invention, it is to provide a white electroluminescent device having high luminous efficiency and long life, and in particular, to provide a white electroluminescent device having excellent productivity and stable chromaticity even in continuous production. it can.

  Furthermore, by including a host compound in the light emitting layer as a preferred embodiment, it is possible to obtain a high internal quantum efficiency in a white light emitting device using a plurality of quantum dots, and to provide a long-life electroluminescent device. it can. In particular, it is possible to provide an electroluminescent device that is excellent in productivity, which is difficult with known combinations, and has stable chromaticity even in continuous production.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows. Quantum dots with high photoluminescence emission quantum yields have very few lattice constant defects between the core and the shell that make up the quantum dots. In addition, since the diffusion of energy is suppressed, it is considered that as a result, it is possible to achieve a white electroluminescence device with high emission efficiency and long life with improved quantum yield and energy transfer between quantum dots. In addition, since it is excellent in stability and the addition amount of the three types of quantum dots is leveled, it is considered that an electroluminescent device having stable chromaticity can be provided even in continuous production.

Schematic sectional view showing an example of the configuration of a white electroluminescence device of a reference example FIG. 1 is a schematic cross-sectional view showing a modification (reverse layer configuration) of FIG. Schematic diagram of atmospheric pressure plasma discharge treatment equipment Schematic of lighting device Cross section of the lighting device

The white electroluminescent device of the present invention is a white electroluminescent device having a reverse layer structure having a single light emitting layer sandwiched between an anode and a cathode provided on a support substrate, the light emitting layer having a thickness of 400 to 500 nm. Quantum dots (BQD) having an emission maximum wavelength in the range, quantum dots (GYQD) having an emission maximum wavelength in the range of 500 to 580 nm, and quantum dots (ORQD) having an emission maximum wavelength in the range of 580 to 650 nm Each of which has a mass ratio in the light-emitting layer of the quantum dots satisfying the following formulas (A) and (B), and photoluminescence of at least two of the quantum dots among the BQD, GYQD, and ORQD Ri der emission quantum yield of 70% or more, further, ho said light emitting layer is represented by the following general formula (1) Characterized that you containing bets compound.

（式中、Ｘは、ＮＲ′、酸素原子、硫黄原子、ＣＲ′Ｒ″、又はＳｉＲ′Ｒ″を表す。ｙ _１ 及びｙ _２ は、各々ＣＲ′又は窒素原子を表す。Ｒ′及びＲ″は、各々水素原子又は置換基を表す。Ａｒ _１ 及びＡｒ _２ は、各々芳香環を表し、それぞれ同一でも異なっていても良い。ｎは０〜４の整数を表す。）
この特徴は、請求項１から請求項８までの請求項に係る発明に共通する技術的特徴である。 Formula (A) 5.5 ≦ BQD / GYQD ≦ 12.0
Formula (B) 1.0 ≦ GYQD / ORQD ≦ 1.3

(In the formula, X represents NR ′, oxygen atom, sulfur atom, CR′R ″, or SiR′R ″. Y ₁ and y ₂ each represent CR ′ or a nitrogen atom. R ′ and R ″. Each represents a hydrogen atom or a substituent, Ar ₁ and Ar ₂ each represent an aromatic ring, and may be the same or different, and n represents an integer of 0 to 4.)
This feature is a technical feature common to the inventions according to claims 1 to 8 .

The embodiments of the present invention, before Symbol X in the general formula (1), it is NR ', further wherein X in the general formula (1) is preferably an oxygen atom. The light emitting layer preferably contains a conductive polymer.

Moreover, it is preferable that the average particle diameter of the said quantum dot exists in the range of 1-20 nm. Furthermore, it is red, green that the quantum dots are composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In ₂ S ₃ , ZnO, CdO, or a mixture thereof. And preferable for obtaining white light from blue-emitting quantum dots.

  Moreover, it is preferable that the molecular weight of the said host compound exists in the range of 500-1000.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

《White electroluminescence device》
A white electroluminescence device referred to will be described with reference to the drawings. As shown in FIG. 1, a reference white electroluminescence device 16 (hereinafter, also referred to as an electroluminescence device) has a flexible support substrate 1. An anode 2 is formed on the flexible support substrate 1, an organic functional layer 15 is formed on the anode 2, and a cathode 8 is formed on the organic functional layer 15.

  The organic functional layer 15 refers to each layer constituting the electroluminescence device 16 provided between the anode 2 and the cathode 8.

  In addition to the light emitting layer 5, the organic functional layer 15 includes, for example, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, and an electron injection layer 7. Or an electronic block layer may be included. The light emitting layer 5 has at least three types of quantum dots 11 (one or more of each of BQD, GYQD, and ORQD) described later as a light emitting material.

  The anode 2, the organic functional layer 15, and the cathode 8 on the flexible support substrate 1 are sealed with a flexible sealing member 10 through a sealing adhesive 9.

Incidentally, (see FIG. 1) These layer structures of electroluminescent devices device 16 Ru der shows an example that is a reference. For example, the electroluminescence device 16 according to the present invention and the organic electroluminescence device 16 referred to may have the layer structures (i) to (ix), but are not limited thereto.
(I) Flexible support substrate / anode / light emitting layer / electron transport layer / cathode / thermal conductive layer / sealing adhesive / sealing member (ii) flexible support substrate / anode / hole transport layer / light emission Layer / electron transport layer / cathode / thermal conductive layer / sealing adhesive / sealing member (iii) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode / Heat conduction layer / adhesive for sealing / sealing member (iv) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat conduction Layer / adhesive for sealing / sealing member (v) flexible support substrate / anode / anode buffer layer / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat Conductive layer / sealing adhesive / sealing member (vi) glass support / anode / hole injection layer / light emitting layer / electron injection layer / cathode / sealing member (vii) glass support / Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode / sealing member (viii) glass support / anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode / sealing member (ix) glass support / cathode / electron transport layer / electron injection layer / emitting layer / hole transport layer / hole injection layer / positive electrode / sealing member "white electroluminescent Organic functional layer 15 of the device >>
Subsequently, the detail of the organic functional layer which comprises the white electroluminescent device of this invention is demonstrated.

The “white electroluminescence device” of the present invention refers to an electroluminescence device that emits white light having three emission colors of red, green, and blue. The color emitted from the electroluminescence device is shown in FIG. 4.16 on page 108 of the “New Color Science Handbook” (edited by the Japan Society for Color Science, University of Tokyo Press, 1985), with a spectral radiance meter CS-2000 (Konica Minolta Optics). It is determined by the color when the result measured by (made by Co., Ltd.) is applied to the CIE chromaticity coordinates. In the present invention, white means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is x = 0.33 ± 0.07, y = 0 when the 2 ° viewing angle front luminance is measured by the above method. Preferably in the region of 33 ± 0.1.

(1) Light emitting layer 5
The light emitting layer constituting the electroluminescent device of 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 the light emitting layer. It may be in the layer or the interface between the light emitting layer and the adjacent layer.

  The light emitting layer according to the present invention is not particularly limited in its configuration as long as the contained light emitting material satisfies the above requirements.

  The total thickness of the light emitting layers in the present invention is preferably in the range of 1 to 100 nm, and more preferably 50 nm or less because a lower driving voltage can be obtained. The film thickness of the light emitting layer is preferably adjusted in the range of 1 to 50 nm. The light emitting layer of the present invention needs to exhibit blue, green, red or intermediate color light emission for showing white light emission.

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

  In the present invention, at least three types (BQD, GYQD, and ORQD each) of quantum dots are contained as the light emitting material of the light emitting layer. Further, the light emitting layer preferably contains a charge transport material, for example, a host compound or a charge transport polymer is preferably contained. It is particularly preferable to contain a host compound.

(1.1) Quantum dot In the white electroluminescent element of this invention, the light emitting layer has at least 3 types (BQD, GYQD, and 1 or more types of ORQD) of quantum dots.

  A quantum dot is composed of a crystal of a semiconductor material and is a fine particle having a particle diameter of about several nanometers to several tens of nanometers. The particle diameter of the quantum dots (fine particles) is specifically 1 to 20 nm, preferably 1 to 10 nm.

  The energy level E of such a fine particle is generally represented by the formula (I) where the Planck constant is “h”, the effective mass of the electron is “m”, and the radius of the fine particle is “R”. .

Formula (1) E∝h ² / mR ²
As shown by the formula (I), the band gap of the fine particles increases in proportion to “R ⁻² ”, and a so-called quantum dot effect is obtained. Thus, the band gap value of a quantum dot can be controlled by controlling and defining the particle diameter of the quantum dot. That is, by controlling and defining the particle diameter of the fine particles, it is possible to provide diversity not found in ordinary atoms. For this reason, it is possible to convert electrical energy into light of the desired wavelength by exciting electrons with light or applying voltage to an electroluminescent device that includes quantum dots to confine electrons and holes in the quantum dots and recombine them. Can be emitted. Such a luminescent quantum dot is referred to as a “quantum dot” in the present application.

  As described above, the average particle diameter of the quantum dots is about several nm to several tens of nm, but when used as one of the white light emitting materials, the particle diameter corresponds to the target light emission color.

  For example, when it is desired to obtain red light emission, the quantum dot particle size is preferably 3 to 20 nm. When green light emission is desired to be obtained, the quantum dot particle size is preferably 1.5 to 10 nm. When it is desired to obtain the quantum dot, it is preferable to set the particle diameter of the quantum dot to 1 to 3 nm.

  As a method for measuring the average particle diameter, a known method can be used.

  For example, the quantum dot particles are observed with a transmission electron microscope (TEM), and the number average particle size of the particle size distribution is obtained therefrom, or the particle size distribution of the quantum dots is measured by a dynamic light scattering method. Examples thereof include a method for obtaining the number average particle size and a method for deriving the particle size distribution from the spectrum obtained by the X-ray small angle scattering method using the particle size distribution simulation calculation of the quantum dots.

  The addition amount of the quantum dots is preferably 0.01 to 100% by mass, more preferably 0.05 to 80% by mass, with respect to 100 parts by mass of all the constituent materials of the layer to be added. Most preferably, it is -60 mass%. In the case of 0.01% by mass or more, white light emission with sufficient luminance efficiency and good color rendering can be obtained.

  The addition amount of each quantum dot necessary for exhibiting white light emission is a quantum dot (referred to as BQD) emitting blue (B) having an emission maximum wavelength within a range of 400 to 500 nm, and a range of 500 to 580 nm. A quantum dot (referred to as GYQD) that emits green (G) having a light emission maximum wavelength and a quantum dot (referred to as ORQD) that emits red (R) having a light emission maximum wavelength within a range of 580 to 650 nm. In the light emitting region, at least one kind of quantum dots is necessary, and the mass ratio of the quantum dots in the light emitting layer must satisfy the following formulas (A) and (B).

Formula (A) 5.5 ≦ BQD / GYQD ≦ 12.0
Formula (B) 1.0 ≦ GYQD / ORQD ≦ 1.3
In addition, these ratios are significantly lower for blue materials than for phosphorescent materials to show white light emission, which means that the exciton confinement effect of quantum dots is higher than that of phosphorescent materials. In addition, as a preferred embodiment, it can be achieved at a high level by a combination with a host compound described later.

  In the white electroluminescence device of the present invention, at least two of BQD, GYQD, and ORQD used in the light emitting layer have a photoluminescence emission quantum yield (hereinafter also referred to as PLQE) of 70% or more. Preferably it is 80% or more, More preferably, it is 90% or more. If it is less than 70%, the number of defects between the core and the shell of the quantum dot is relatively large, resulting in insufficient energy diffusion and durability as a particle. Become.

  Preferably, PLQE is such that both GYQD and ORQD are 70% or more. Furthermore, it is preferable that BQD, GYQD, and ORQD are all 70% or more.

  The PLQE of each quantum dot can be measured using the method described in International Publication No. 2008/063652, except those described in the catalog of commercial products.

  The PL spectrum can be measured using a spectrophotometer such as USB2000 (manufactured by Ocean Optics) or CARY Eclipse (manufactured by Agilent Technologies) at room temperature (23 to 25 ° C.) and an excitation wavelength of 373 nm.

  Quantum dots with high PLQE have very few crystal lattice defects between the core and the shell that constitute the quantum dots. Therefore, in addition to the high exciton confinement effect in the core of the quantum dots, energy diffusion is inherent. As a result, it is considered that the quantum yield is improved and the energy transfer between the quantum dots is suppressed as a result. In addition, it is considered that a white electroluminescence device with stable chromaticity can be provided even in continuous production because of excellent stability and the level of addition of the three types of quantum dots.

  In addition, since the above-described phosphorescent light emitting material has a relatively long excitation lifetime of the order of millisecond or microsecond, if the concentration in the layer is too high, the energy of excitons relaxes and disappears, so-called concentration quenching problem There is. However, by adding these quantum dots to the light emitting layer, not only can the light emission of the quantum dots themselves be obtained, but the details are unknown, but besides the improvement of carrier injection by the combination of quantum dots and the above-mentioned host compound, It is considered that the effect of suppressing the energy transfer presumed to be due to the improvement of the dispersibility of the quantum dots due to the surface energy of the host compound and the accompanying improvement in the light emission efficiency can be obtained.

Examples of the constituent material of the quantum dot include a simple substance of a periodic table group 14 element such as carbon, silicon, germanium, and tin, a simple substance of a periodic table group 15 element such as phosphorus (black phosphorus), and a periodicity of selenium, tellurium, and the like. Table 16 group element simple substance, compound consisting of a plurality of periodic table group 14 elements such as silicon carbide (SiC), tin oxide (IV) (SnO ₂ ), tin sulfide (II, IV) (Sn (II) Sn (IV) S ₃ ), tin sulfide (IV) (SnS ₂ ), tin (II) sulfide (SnS), tin (II) selenide (SnSe), tin telluride (II) (SnTe), lead sulfide (II) ) (PbS), lead selenide (II) (PbSe), lead telluride (II) (PbTe) periodic table group 14 element and periodic table group 16 element compound, boron nitride (BN), phosphorus Boron halide (BP), Boron arsenide (BAs), Aluminum nitride (AlN), Al phosphide Ni (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium antimonide (GaSb), indium nitride (InN), Compound (or III-V group compound semiconductor) of periodic table group 13 element and periodic table group 15 element such as indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), aluminum sulfide ( Al ₂ S ₃ ), aluminum selenide (Al ₂ Se ₃ ), gallium sulfide (Ga ₂ S ₃ ), gallium selenide (Ga ₂ Se ₃ ), gallium telluride (Ga ₂ Te ₃ ), indium oxide (In ₂₎ O _3), indium sulfide _{(In 2 S} 3), indium selenide (I ₂ Se _3), compounds of tellurium indium _(In 2 Te ₃₎ periodic table group 13 elements and the periodic table group 16 element such as, thallium chloride (I) (TlCl), thallium bromide (I) (TlBr ), Compounds of group 13 elements of the periodic table and elements of group 17 of the periodic table such as thallium (I) iodide (TlI), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), tellurium Zinc iodide (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe) ) periodic table group 12 element and the periodic table compound of group 16 element such as (or II-VI compound semiconductor), arsenic sulfide (III) (as 2 S _3), selenium arsenic (III _(As 2 _Se 3), telluride arsenic _{(III) (As 2 Te 3} ), antimony sulfide _{(III) (Sb 2 S 3} ), selenium antimony _{(III) (Sb 2 Se 3} ), antimony telluride (III ) (Sb ₂ Te ₃ ), bismuth sulfide (III) (Bi ₂ S ₃ ), bismuth selenide (III) (Bi ₂ Se ₃ ), bismuth telluride (III) (Bi ₂ Te ₃ ), etc. Compounds of Group 15 elements and Group 16 elements of the periodic table, Group 11 elements of the periodic table and Group 16 of the periodic table such as copper (I) (Cu ₂ O), copper selenide (Cu ₂ Se), etc. Periodic tables of compounds with elements, copper chloride (I) (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), silver chloride (AgCl), silver bromide (AgBr), etc. Compounds of Group 11 elements and Periodic Table Group 17 elements, nickel oxide (II) (N compounds of periodic table group 10 elements such as iO) and periodic table group 16 elements, periodic table group 9 elements such as cobalt (II) oxide (CoO), cobalt sulfide (II) (CoS) and periodic table Compounds with Group 16 elements, compounds of Group 8 elements of the periodic table such as triiron tetroxide (Fe ₃ O ₄ ), iron (II) sulfide (FeS), and Group 16 elements of the periodic table, manganese (II) oxide A compound of a periodic table group 7 element such as (MnO) and a periodic table group 16 element, a periodic table group 6 element such as molybdenum sulfide (IV) (MoS ₂ ), tungsten oxide (IV) (WO ₂ ), etc. Compounds with Group 16 elements of the Periodic Table, Periodic Table Group 5 elements such as vanadium (II) oxide (VO), vanadium oxide (IV) (VO ₂ ), tantalum oxide (V) (Ta ₂ O ₅ ) and the period Table compound of group 16 element, a titanium oxide _{(TiO 2, Ti 2 O 5} , Ti 2 O , A compound of Group 4 of the periodic table element and Periodic Table Group 16 element of _Ti 5 _{O 9,} etc.) and the like, magnesium sulfide (MgS), the second group elements and the periodic table periodic table such as magnesium selenide (MgSe) Compounds with group 16 elements, cadmium (II) chromium (III) (CdCr ₂ O ₄ ), cadmium selenide (II) chromium (III) (CdCr ₂ Se ₄ ), copper sulfide (II) chromium (III) ( Examples thereof include chalcogen spinels such as CuCr ₂ S ₄ ), mercury (II) selenide, chromium (III) (HgCr ₂ Se ₄ ), barium titanate (BaTiO ₃ ), etc., but SnS ₂ , SnS, SnSe, SnTe, PbS , PbSe, PbTe, etc. compounds of periodic table group 14 elements and periodic table group 16 elements, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, etc. III-V group compound semiconductors, Ga ₂ O ₃ , Ga ₂ S ₃ , Ga ₂ Se ₃ , Ga ₂ Te ₃ , In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ , In ₂ Te _3, etc. Compounds of Group 13 elements and Group 16 elements of the Periodic Table, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe and other II-VI group compound semiconductors, As ₂ O ₃ , As ₂ S ₃ , As ₂ Se ₃ , As ₂ Te ₃ , Sb ₂ O ₃ , Sb ₂ S ₃ , Sb ₂ Se ₃ , Sb ₂ Te ₃ , Bi ₂ O ₃ , Bi ₂ S ₃ , Bi ₂ A compound of a periodic table group 15 element such as Se ₃ or Bi ₂ Te ₃ and a group 16 element of the periodic table, a compound of periodic table group 2 element such as MgS or MgSe, and a group 16 element of the periodic table are preferable, Among them, Si, Ge GaN, GaP, InN, InP, Ga ₂ O ₃ , Ga ₂ S ₃ , In ₂ O ₃ , In ₂ S ₃ , ZnO, ZnS, CdO, and CdS are more preferable.

  Since these substances do not contain highly toxic negative elements, they are excellent in environmental pollution resistance and safety to living organisms, and since a pure spectrum can be stably obtained in the visible light region, light emitting devices Is advantageous for the formation of Of these materials, CdSe, ZnSe, and CdS are preferable in terms of light emission stability. From the viewpoints of luminous efficiency, high refractive index, and safety, ZnO and ZnS quantum dots are preferable. Moreover, said material may be used by 1 type and may be used in combination of 2 or more type.

  Note that the above-described quantum dots can be doped with a small amount of various elements as impurities as necessary. By adding such a doping substance, the emission characteristics can be greatly improved.

  The band gap energy of the quantum dot of the present invention is preferably not more than the band gap energy of the adjacent layer of the light emitting layer, and more preferably not more than the band gap energy of the host material of the light emitting layer. Specifically, it is preferably in the range of 1.8 eV to 3.2 eV, more preferably 2.2 eV to 3 eV, and most preferably 2.6 eV to 3.0 eV.

  Methods for estimating the energy levels of these organic and inorganic functional materials include scanning tunneling spectroscopy, ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, energy levels determined by Auger electron spectroscopy, and optically. There is a method for estimating the band gap energy.

  These quantum dots not only emit light by direct recombination of holes and electrons in the light emitting material, but also the excitation generated in the organic electron block hole transport layer, organic light emitting layer, or hole block electron transport layer. The energy of the child may be absorbed by the quantum dot to obtain light emission from the core of the quantum dot.

  The surface of the quantum dot is preferably coated with an inert inorganic coating layer or a coating composed of an organic ligand. That is, the surface of the quantum dot preferably has a core region composed of quantum dots and a shell region composed of an inert inorganic coating layer or organic ligand.

  The core / shell structure is preferably formed of at least two types of compounds, and a gradient structure may be formed of two or more types of compounds. This effectively prevents aggregation of the quantum dots in the coating liquid, improves the dispersibility of the quantum dots, improves the luminance efficiency, and prevents color shifts that occur when driven continuously. Can be suppressed. Further, the light emission characteristics can be stably obtained by the presence of the coating layer.

  Moreover, when the surface of the quantum dot is coated with a coating, a surface modifier as described later can be reliably supported in the vicinity of the surface of the quantum dot.

  Although the thickness of a film is not specifically limited, It is preferable that it is 0.1-10 nm, and it is more preferable that it is 0.1-5 nm. In general, if the emission color can be controlled by the size of the quantum dots and the thickness of the coating is within the above range, the thickness of the coating is less than one quantum dot from the thickness corresponding to several atoms. The quantum dots can be filled with high density, and a sufficient amount of light emission can be obtained. Further, the presence of the coating can suppress the transfer of non-emissive electron energy due to the defects existing on the particle surfaces of the core particles and the electron traps on the dangling bonds, and the decrease in quantum efficiency can be suppressed.

(1.2) Functional surface modifier It is preferable that the surface modifier is adhered to the surface of the quantum dot in the coating solution. Thereby, especially the dispersibility of the quantum dot in a coating liquid can be made excellent. Also, by attaching a surface modifier to the surface of the quantum dots during the manufacture of the quantum dots, the shape of the formed quantum dots has a high sphericity, and the particle size distribution of the quantum dots can be kept narrow. Therefore, for example, it can be made particularly excellent.

  These functional surface modifiers may be those directly attached to the surface of the quantum dot, or those attached via the shell (the surface modifier is directly attached to the shell, It may be that which is not in contact.

  Examples of the surface modifier include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, and the like. Trialkylphosphines; polyoxyethylene alkylphenyl ethers such as polyoxyethylene n-octylphenyl ether and polyoxyethylene n-nonylphenyl ether; tri (n-hexyl) amine, tri (n-octyl) amine, tri ( Tertiary amines such as n-decyl) amine; tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide Organic phosphorus compounds such as tridecylphosphine oxide; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine and quinolines; hexylamine and octyl Aminoalkanes such as amine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine; dialkyl sulfides such as dibutyl sulfide; dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide; sulfur-containing aromatic compounds such as thiophene Organic sulfur compounds such as: higher fatty acids such as palmitic acid, stearic acid and oleic acid; alcohols; sorbitan fatty acid esters; fatty acid-modified polyesters Ters; tertiary amine-modified polyurethanes; polyethyleneimines and the like. When the quantum dots are prepared by the method described later, the surface modifier is coordinated to the fine particles in the high-temperature liquid phase. In particular, trialkylphosphines, organic phosphorus compounds, aminoalkanes, tertiary amines, organic nitrogen compounds, dialkyl sulfides, dialkyl sulfoxides, organic sulfur compounds Higher fatty acids and alcohols are preferred. By using such a surface modifier, the dispersibility of the quantum dots in the coating solution can be made particularly excellent. Moreover, the shape of the quantum dot formed at the time of manufacture of a quantum dot can be made into a higher sphericity, and the particle size distribution of a quantum dot can be made sharper.

(1.3) Quantum Dot Manufacturing Method Examples of the quantum dot manufacturing method include the following conventional quantum manufacturing methods, but are not limited thereto, and are any known method. Can be used. For example, as a process under high vacuum, a molecular beam epitaxy method, a CVD method or the like; As a liquid phase production method, an aqueous raw material is an alkane such as n-heptane, n-octane, isooctane, or benzene, toluene. Inverted micelles, which exist as reverse micelles in non-polar organic solvents such as aromatic hydrocarbons such as xylene, and crystal growth in this reverse micelle phase, inject a thermally decomposable raw material into a high-temperature liquid-phase organic medium Examples thereof include a hot soap method for crystal growth and a solution reaction method involving crystal growth at a relatively low temperature using an acid-base reaction as a driving force, as in the hot soap method.

  Any method can be used from these production methods, and among these, the liquid phase production method is preferred.

  In the liquid phase production method, an organic surface modifier that exists on the surface during the synthesis of quantum dots is referred to as an initial surface modifier.

  For example, examples of the initial surface modifier in the hot soap method include trialkylphosphines, trialkylphosphine oxides, alkylamines, dialkyl sulfoxides, alkanephosphonic acid and the like. These initial surface modifiers are preferably exchanged for the above-described functional surface modifiers by an exchange reaction.

  Specifically, for example, the initial surface modifier such as trioctyl phosphine oxide obtained by the hot soap method described above is obtained by performing the functional surface modification described above by an exchange reaction performed in a liquid phase containing the functional surface modifier. It is possible to replace it with an agent.

  Below, an example of the manufacturing method of a quantum dot is shown.

<1> Production example 1 of quantum dots
First, CdO powder (1.6 mmol, 0.206 g; Aldrich, + 99.99%) and oleic acid (6.4 mmol, 1.8 g; Aldrich, 95%) were mixed with 40 ml of trioctylamine (TOA, Aldrich, 95 %). The mixed solution was heat-treated at 150 ° C. while stirring at high speed, and the temperature was increased to 300 ° C. while N ₂ was allowed to flow. Then, at 300 ° C., 0.2 ml of 2.0 mol / L Se (Alfa Aesar) added to trioctylphosphine (TOP, Strem, 97%) is injected into the Cd-containing mixture at high speed.

  After 90 seconds, 1.2 mmol of n-octanethiol added to TOA (210 μl in 6 ml) is injected at a rate of 1 ml / min using a syringe pump and allowed to react for 40 minutes.

Next, 0.92 g of zinc acetate and 2.8 g of oleic acid are dissolved in 20 ml of TOA at 200 ° C. in an N ₂ atmosphere to prepare a 0.25 mol / L Zn precursor solution.

  A 16 ml aliquot of Zn-oleic acid solution (heated at 100 ° C.) is then injected into the Cd-containing reaction medium at a rate of 2 ml / min. Then, 6.4 mmol n-octanethiol in TOA (1.12 ml in 6 ml) is infused at a rate of 1 ml / min using a syringe pump.

  The entire reaction is performed over 2 hours. After the reaction is complete, the product is cooled to about 50-60 ° C. and the organic sludge is removed by centrifugation (5,600 rpm). Add ethanol (Fisher, HPLC grade) until there is no opaque mass. Subsequently, the precipitate obtained by centrifugation is dissolved in toluene (Sigma-Aldrich, Anhydrous 99.8%) to obtain a CdSe / CdS / ZnS core-shell quantum dot colloidal solution.

<2> Production example 2 of quantum dots
When a quantum dot having a core / shell structure of CdSe / ZnS is to be obtained, (CH ₃ ) ₂ Cd (dimethyl cadmium), TOPSe (trioctylphosphine selenium) is used as an organic solvent using TOPO (trioxyphosphine oxide) as a surfactant. A precursor material corresponding to the core (CdSe) is injected to generate a crystal, and is maintained at a high temperature for a certain period of time so that the crystal grows at a certain size, and then corresponds to the shell (ZnS). CdSe / ZnS quantum dots capped with TOPO can be obtained by injecting the precursor material so that a shell is formed on the surface of the core already formed.

<3> Production example 3 of quantum dots
Under an argon stream, 7.5 g of tri-n-octylphosphine oxide (TOPO) (manufactured by Kanto Chemical Co.), 2.9 g of stearic acid (manufactured by Kanto Chemical Co., Ltd.), 620 mg of n-tetradecylphosphonic acid (manufactured by AVOCADO), And 250 mg of cadmium oxide (made by Wako Pure Chemical Industries Ltd.) was added, and it heat-mixed at 370 degreeC. After naturally cooling this to 270 ° C., a solution of 200 mg of selenium (STREM CHEMICAL) dissolved in 2.5 ml of tributylphosphine (manufactured by Kanto Chemical Co.) was added in advance, dried under reduced pressure, and CdSe coated with TOPO. Get fine particles.

  Next, 15 g of TOPO was added to the obtained CdSe fine particles and heated, and subsequently a solution of 1.1 g of zinc diethyldithiocarbamate (manufactured by Tokyo Kasei Co.) dissolved in 10 ml of trioctylphosphine (manufactured by Sigma Aldrich) was added at 270 ° C. Then, nanoparticles with CdSe nanocrystals with TOPO fixed on the surface and ZnS as the core (hereinafter also referred to as TOPO fixed quantum dots) were obtained. In addition, the quantum dot of this state is soluble in organic solvents, such as toluene and tetrahydrofuran (THF).

  Thereafter, the prepared TOPO fixed quantum dots were dissolved in THF, heated to 85 ° C., and N-[(S) -3-mercapto-2-methylpropionyl] -L-proline (Sigma) dissolved in ethanol there. (Aldrich) 100 mg was added dropwise and refluxed for about 12 hours. After refluxing for 12 hours, an aqueous NaOH solution was added, and the mixture was heated at 90 ° C. for 2 hours to evaporate THF. By purifying and concentrating the obtained unpurified quantum dots using ultrafiltration (Millipore, "Microcon") and Sephadex column (Amersham Biosciences, "MicroSpin G-25 Columns"). A hydrophilic quantum dot in which N-[(S) -3-mercapto-2-methylpropionyl] -L-proline is immobilized on the surface of the quantum dot can be produced.

(1.4) Host compound As a host compound applied to the light emitting layer constituting the white electroluminescent device, the emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum is 459 nm or less (up to 3.0 eV). It is a compound with a short emission wavelength. That is, the compound is preferably a compound having a high triplet energy level. Preferably it exists in the range of 337-459 nm or less, More preferably, it is in the range of 414-459 nm or less (2.7-3.0 eV).

  In this way, even in the triplet energy level, by using a host compound having a wider band gap than the quantum dot compound, carrier injection into the quantum dot compound and exciton confinement become efficient. Increased lifetime due to efficient light emission and reduced thermal deactivation process can be obtained.

  The emission wavelength attributed to the 0-0 transition band in the phosphorescence spectrum of the host compound according to the present invention can be determined by the following method.

  First, the host compound to be measured is dissolved in a well-deoxygenated ethanol / methanol = 4/1 (vol / vol) mixed solvent, put into a phosphorescence measurement cell, and then excited with liquid nitrogen temperature of 77K. After irradiating with excitation light, an emission spectrum at 100 ms is measured. 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 shorter delay time, but phosphorescence and fluorescence cannot be separated if the delay time is shortened so that it cannot be distinguished from fluorescence. Since this is a problem, it is necessary to select a delay time that can be separated.

  For the host compound that cannot be dissolved in the solvent system, any solvent that can dissolve the host compound may be used. In practice, the above-described measurement method is considered to have no problem because the solvent effect of phosphorescence wavelength is negligible.

  Next, the 0-0 transition band is obtained. In the present invention, in the phosphorescence spectrum chart obtained by the above-described measurement method, an emission band having an emission maximum wavelength that appears on the shortest wavelength side (emission band). ) Is the 0-0 transition 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 the excitation light irradiation (for convenience, this is called a steady light spectrum) is expanded, and after the excitation light is irradiated, the emission spectrum after 100 ms (for convenience, this is called the phosphorescence spectrum) It can be determined by reading the peak wavelength of the phosphorescence spectrum from the stationary light spectrum portion derived from the superposed phosphorescence 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.

  As a measurement apparatus that can be used in the above measurement, a fluorescence photometer F4500 manufactured by Hitachi High-Technology Corporation can be exemplified.

  As a host compound contained in the light emitting layer of the organic EL device of the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% 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, as a host compound used for this invention, it is preferable that the emission wavelength which belongs to the 0-0 transition band in a phosphorescence spectrum is 459 nm or less. It may be a conventionally known low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound (polymerizable light-emitting host) having a polymerizable group such as a vinyl group or an epoxy group. In the case of using a polymer material, the compound is likely to cause a phenomenon that the solvent is difficult to escape, such as swelling or gelation due to the compound taking in the solvent. Therefore, in order to prevent this, it is preferable that the molecular weight is not high. It is preferable to use a material having a molecular weight of 2000 or less at the time, more preferably a material having a molecular weight of 1000 or less at the time of coating, and a host compound having a molecular weight in the range of 500 to 1000 is particularly preferable.

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

  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, etc., and a compound having the above-mentioned conditions defined in the present invention can be selected and used. it can.

  Furthermore, the host compound according to the present invention is preferably a compound represented by the following general formula (1). This is because the compound represented by the following general formula (1) has a condensed ring structure and thus has a high carrier transport property, and also has the above-described high triplet energy level (0-0 band of phosphorescence). It is.

In the general formula (1), X represents NR ′, oxygen atom, sulfur atom, CR′R ″, or SiR′R ″. y ₁ and y ₂ each represent CR ′ or a nitrogen atom. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar ₁ and Ar ₂ each represent an aromatic ring and may be the same or different. N represents an integer of 0 to 4. As the host compound represented by the general formula (1), a carbazole derivative is particularly preferable.

In X, y ₁ and y ₂ in the general formula (1), examples of the substituent represented by R ′ and R ″ include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, t -Butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg, vinyl group, allyl group) Group), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl Group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl , Indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1 , 2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group Quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is nitrogen (Represented by atoms replaced), quinoxalini Group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy) Group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.) Alkylthio groups (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio groups (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio Group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group ( For example, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylamino) Sulfonyl groups, dodecylaminosulfonyl groups, phenylaminosulfonyl groups, naphthylaminosulfonyl groups, 2-pyridylaminosulfonyl groups, etc.), acyl groups (eg Acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethyl group) Carbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octyl Rucarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group) Cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, Ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2 Pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group) Etc.), alkylsulfonyl groups (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl groups or heteroarylsulfonyl groups (for example, phenylsulfonyl) Group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butyrate) Amino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom), fluorinated carbonization Hydrogen group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), 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. A plurality of these substituents may be bonded to each other to form a ring.

  Among them, a compound in which X is NR ′ or an oxygen atom in the general formula (1) is preferable as a structure having a low LUMO energy level and excellent electron transport properties. That is, a compound having a (aza) carbazole ring or a (aza) dibenzofuran ring is preferable. More preferably, it is a compound having a (aza) carbazole ring which is more excellent in electron transport property. Here, as R ′, an aromatic hydrocarbon group (also referred to as an aromatic carbocyclic group, an aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, Azulenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, biphenylyl) or aromatic heterocyclic groups (eg furyl, thienyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl) Group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.) are particularly preferred.

  The above aromatic hydrocarbon group and aromatic heterocyclic group may each have a substituent represented by R ′ and R ″ in X of the general formula (1).

In the general formula (1), examples of the atoms represented by y ₁ and y ₂ include CR ′ and nitrogen atom, and CR ′ is more preferable. Such a compound is excellent in hole transportability, and can efficiently recombine and emit holes and electrons injected from the anode and cathode in the light emitting layer.

In the general formula (1), examples of the aromatic ring represented by Ar ₁ and Ar ₂ include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent represented by R ′ and R ″ in X of the general formula (1).

In the general formula (1), examples of the aromatic hydrocarbon ring represented by Ar ₁ and Ar ₂ include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, Naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, Examples include a picene ring, a pyrene ring, a pyranthrene ring, and an anthraanthrene ring.

In the general formula (1), examples of the aromatic heterocycle represented by Ar ₁ and Ar ₂ include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, and a pyrazine. Ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, Cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) Etc.) It is.

  These rings may further have substituents represented by R ′ and R ″ in the general formula (1).

Among the above, in the general formula (1), the aromatic ring represented by Ar ₁ and Ar ₂ is preferably a carbazole ring, carboline ring, dibenzofuran ring, or benzene ring, and more preferably used. , A carbazole ring, a carboline ring, and a benzene ring, more preferably a benzene ring having a substituent, and particularly preferably a benzene ring having a carbazolyl group.

In the general formula (1), the aromatic rings represented by Ar ₁ and Ar ₂ are each preferably a condensed ring of three or more rings, and as an aromatic hydrocarbon condensed ring in which three or more rings are condensed. Specifically, naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, Coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene ring, naphthocoronene ring , Ovalene ring, Ansula Ntoren ring and the like. In addition, these rings may further have the above substituent.

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

  In the general formula (1), n represents an integer of 0 to 4, preferably 0 to 2, and particularly 1 to 2 when X is an oxygen atom or a sulfur atom. It is preferable.

  In the present invention, a host compound having both a dibenzofuran ring and a carbazole ring is particularly preferable.

  As the host compound according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (2). That is, a compound having a carbazole ring substituted at the 3-position with a phenyl group is preferable. This is because such a compound tends to be particularly excellent in carrier transportability and excellent in carrier injection into quantum dots.

In the general formula (2), Ar _{3 to} Ar ₅ each represent an aromatic ring, and may be the same or different. n1 represents an integer of 0 to 4, and n2 represents an integer of 0 to 5.

Examples of the aromatic ring represented by Ar _{3 to} Ar ₅ include the same aromatic rings as those represented by Ar ₁ and Ar ₂ in the general formula (1).

  Hereinafter, as a host compound according to the present invention having an emission wavelength attributed to 0-0 transition band in phosphorescence spectrum of 459 nm or less, a compound represented by general formula (1), represented by general formula (2) Examples of such compounds and compounds having other structures are shown below, but are not limited thereto.

(1.5) Conductive polymer In the white electroluminescent device of the present invention, the light emitting layer may contain a conductive polymer.

  Preferable examples of the conductive polymer include polyacetylene, poly (p-phenylene vinylene), polypyrrole, polythiophene, polyaniline, poly (p-phenylene sulfide) and the like. These conductive polymers are considered to have a function of facilitating a conductive path between the quantum dot light emitting material, the above-described charge transporting material, and the host compound in the light emitting layer.

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

(2) Injection layer: hole injection layer 3, electron injection layer 7
In the organic EL device of the present invention, the injection layer can be provided as necessary. As the injection layer, there are an electron injection layer and a hole injection layer. As described above, the injection layer may exist between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer.

  The injection layer referred to in the present invention is a layer provided between the electrode and the organic functional layer in order to lower the driving voltage and improve the light emission luminance. 2) Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “S. Co., Ltd.”, and includes a hole injection layer and an electron injection layer.

  The details of the hole injection layer are described, for example, in JP-A-9-45479, JP-A-9-260062, and JP-A-8-288069. Injection materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives. , Polymers containing silazane derivatives, aniline copolymers, polyarylalkane derivatives, or conductive polymers, preferably polythiophene derivatives, polyaniline derivatives, and polypyrrole derivatives, more preferably polythiol derivatives. It is phen derivatives.

  Details of the electron injection layer are described in, for example, JP-A-6-325871, JP-A-9-17574, and JP-A-10-74586, and specifically, strontium, aluminum and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide. In the present invention, the buffer layer (injection layer) is desirably a very thin film, and potassium fluoride and sodium fluoride are preferable. The film thickness is about 0.1 nm to 5 μm, preferably 0.1 to 100 nm, more preferably 0.5 to 10 nm, and most preferably 0.5 to 4 nm.

(3) Hole transport layer 4
As the hole transport material constituting the hole transport layer, the same compounds as those applied in the hole injection layer can be used, and further, porphyrin compounds, aromatic tertiary amine compounds, and styryl. It is preferable to use an amine 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-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), JP-A-11-251067, J. MoI. Huang et. al. It is also possible to use a hole transport material that has a so-called p-type semiconducting property as described in the literature (Applied Physics Letters 80 (2002), p. 139), JP 2003-519432 A. it can.

  The hole transport layer is 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. Can do. 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. This hole transport layer may have a single layer structure composed of one or more of the above materials.

  Hereinafter, although the preferable specific example ((1)-(60)) of the compound used for the hole transport material of the electroluminescent device of this invention is given, this invention is not limited to these.

  In addition, n described in the above exemplary compounds represents the degree of polymerization and represents an integer having a weight average molecular weight in the range of 50,000 to 200,000. If the weight average molecular weight is less than this range, there is a concern of mixing with other layers during film formation due to the high solubility in the solvent. Even if a film can be formed, the light emission efficiency does not increase at a low molecular weight. When the weight average molecular weight is larger than this range, problems arise due to difficulty in synthesis and purification. Since the molecular weight distribution increases and the residual amount of impurities also increases, the light emission efficiency, voltage, and lifetime of the electroluminescence device deteriorate.

  These polymer compounds are disclosed in Makromol. Chem. , Pages 193, 909 (1992) and the like.

(4) Electron transport layer 6
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, 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 is injected from the cathode. As long as it has a function of transmitting electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, fluorene derivatives, carbazole derivatives, azacarbazole Examples thereof include metal complexes such as derivatives, oxadiazole derivatives, triazole derivatives, silole derivatives, pyridine derivatives, pyrimidine derivatives, and 8-quinolinol derivatives.

  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 transport material.

  Among these, a carbazole derivative, an azacarbazole derivative, a pyridine derivative, and the like are preferable in the present invention, and an azacarbazole derivative is more preferable. Preferable examples of the electron transport material used for the electron transport layer 6 of the white electroluminescence device of the present invention are compounds represented by the following general formulas (3) to (8).

In the general formula (3), E _{101 to} E ₁₀₈ each represent —C (R ₁₂ ) ═ or N═, and at least one of E _{101 to} E ₁₀₈ is —N═. Moreover, R < ₁₁ > in General formula (3) and said R < ₁₂ > represent a hydrogen atom or a substituent.

  Examples of this substituent include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group). Etc.), cycloalkyl groups (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl groups (for example, vinyl group, allyl group, etc.), alkynyl groups (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon groups (aromatic Also called group carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group , Pyrenyl group, biphenylyl group), aromatic heterocyclic group (for example, Furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group Any carbon atom constituting the carboline ring is substituted with a nitrogen atom), 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.), cycloalkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group ( For example, Nonoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group) Etc.), arylthio groups (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl groups (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryl Oxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group) 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, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenyl group Carbonyloxy group, etc.), amide groups (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonyl) Amino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexyl) Aminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl Bonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group naphthylureido) Group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2 -Pyridylsulfinyl group etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2 -Ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (eg, amino group, ethylamino group, Dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, piperidyl group (also called piperidinyl group), 2,2,6,6 -Tetramethylpiperidinyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluoro) Phenyl group, etc.), cyano group, Toro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), phosphate ester group (for example, dihexyl phosphoryl group, etc.), phosphorous acid An ester group (for example, diphenylphosphinyl group etc.), a phosphono group, etc. are mentioned.

  Some of 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.

The general formula (4) is also an embodiment of the general formula (3). In the formula of the general formula (4), Y21 represents a divalent linking group composed of an arylene group, a heteroarylene group, or a combination thereof. E _{201 to} E ₂₁₆ and E _{221 to} E ₂₃₈ each represent —C (R ₂₁ ) ═ or N═, and R ₂₁ represents a hydrogen atom or a substituent. However, at least one of E _{221 to} E ₂₂₉ and at least one of E _{230 to} E ₂₃₈ represents -N =. k21 and k22 represent an integer of 0 to 4, but k21 + k22 is an integer of 2 or more.

In the general formula (2), examples of the arylene group represented by Y ₂₁ include an o-phenylene group, p-phenylene group, naphthalenediyl group, anthracenediyl group, naphthacenediyl group, pyrenediyl group, naphthylnaphthalenediyl group, and biphenyl. Diyl group (for example, [1,1′-biphenyl] -4,4′-diyl group, 3,3′-biphenyldiyl group, 3,6-biphenyldiyl group), terphenyldiyl group, quaterphenyldiyl Group, kinkphenyldiyl group, sexiphenyldiyl group, septiphenyldiyl group, octiphenyldiyl group, nobiphenyldiyl group, deciphenyldiyl group and the like.

In the general formula (4), examples of the heteroarylene group represented by Y ₂₁ include a carbazole ring, a carboline ring, a diazacarbazole ring (also referred to as a monoazacarboline ring, and one of carbon atoms constituting the carboline ring). Derived from the group consisting of triazole ring, pyrrole ring, pyridine ring, pyrazine ring, quinoxaline ring, thiophene ring, oxadiazole ring, dibenzofuran ring, dibenzothiophene ring, indole ring) And the like.

  As a preferred embodiment of the divalent linking group consisting of an arylene group, heteroarylene group or a combination thereof represented by Y21, among the heteroarylene groups, a condensed aromatic heterocycle formed by condensation of three or more rings. A group derived from a condensed aromatic heterocyclic ring formed by condensing three or more rings is preferably included, and a group derived from a dibenzofuran ring or a dibenzothiophene ring is preferable. Are preferred.

In the general formula _(4), if -C _{(R 21)} = in _{R 21,} represented respectively by _{E 201 ~E 216, E 221 ~E} 238 is a substituent, and examples of the substituent of the general formula The substituents exemplified as R ₁₁ and R _{12 in} (3) are similarly applied.

In the general formula _(4), more than six of E 201 _{to E 208,} and more six of _{E209～ E216} are each -C _{(R 21)} = is preferably represented by.

In the general formula _(4), at least one of E 225 _{to E 229,} and at least one of _E 234 _{to E 238} preferably represents a -N =.

Further, in the general formula _(4), any one of E 225 _{to E 229,} and any one of _E 234 _{to E 238} preferably represents a -N =.

In the general formula _{(4), E} 221 ~E ₂₂₄ and _E 230 _{to E 233} may be mentioned as each -C _{(R 21)} = are preferable embodiments be represented by.

Further, in the compound represented by the general formula (4), it is preferable that E ₂₀₃ is represented by —C (R ₂₁ ) ═ and R ₂₁ represents a linking site, and E ₂₁₁ is also represented by —C (R ₂₁ ) = and R ₂₁ preferably represents a linking site.

_Further, it is preferable _{that E 225} and _{E 234} are represented by -N _{=, E} 221 ~E ₂₂₄ and _E 230 _{to E 233} are each -C _{(R 21)} = is preferably represented by.

The general formula (5) is also an embodiment of the general formula (3). In the general formula (5), E _{301 to} E ₃₁₂ each represent —C (R ₃₁ ) ═, and R ₃₁ represents a hydrogen atom or a substituent. Y ₃₁ represents a divalent linking group composed of an arylene group, a heteroarylene group, or a combination thereof.

In the general formula _(5), if -C _{(R 31)} = in _{R 31} represented by each of E 301 _{to E 312} are substituents, examples of the substituent of the general formula (1) R _The substituents exemplified as ₁₁ and R ₁₂ are similarly applied.

In the general formula (5), the arylene group represented by Y _31, a preferred embodiment of the divalent linking group of a heteroarylene group, or a combination thereof, is of the general formula similar to Y ₂₁ (4) Can be mentioned.

The general formula (6) is also an embodiment of the general formula (3). In the general formula (6), E _{401 to} E ₄₁₄ each represent —C (R ₄₁ ) ═, and R ₄₁ represents a hydrogen atom or a substituent. Ar ₄₁ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. Furthermore, k41 represents an integer of 3 or more.

In the general formula _(6), if -C _{(R 41)} = in _{R 41} represented by each of E 401 _{to E 414} are substituents, examples of the substituent of the general formula (3) R _The substituents exemplified as ₁₁ and R ₁₂ are similarly applied.

In the general formula (6), when Ar ₄₁ represents an aromatic hydrocarbon ring, the aromatic hydrocarbon ring includes a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, a 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, Examples include a pentaphen ring, a picene ring, a pyrene ring, a pyranthrene ring, and an anthraanthrene ring. These rings may further have the substituents exemplified as R ₁₁ and R _{12 in} the general formula (3).

In the general formula (6), when Ar ₄₁ represents an aromatic heterocycle, the aromatic heterocycle includes a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, and a pyrazine ring. , Triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole Ring, azacarbazole ring and the like. The azacarbazole ring refers to one in which at least one carbon atom of the benzene ring constituting the carbazole ring is replaced with a nitrogen atom. These rings may further have the substituents exemplified as R ₁₁ and R ₁₂ in the general formula (3).

In the general formula (7), at least one of E ₅₀₁ and E ₅₀₂ is a nitrogen atom, at least one of E _{511 to} E ₅₁₅ is a nitrogen atom, and E _{521 to} E ₅₂₅ At least one of them is a nitrogen atom. R ₅₁ represents a substituent.

In the general formula (7), when R ₅₁ represents a substituent, the substituents exemplified as R ₁₁ and R _{12 in} the general formula (3) are similarly applied as examples of the substituent.

In the general formula (8), E _{601 to} E ₆₁₂ each represent —C (R ₆₁ ) ═ or N═, and R ₆₁ represents a hydrogen atom or a substituent. Ar ₆₁ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring.

In the general formula _(8), if -C _{(R 61)} = in _{R 61} represented by each of E 601 _{to E 612} are substituents, examples of the substituent of the general formula (3) R _The substituents exemplified as ₁₁ and R ₁₂ are similarly applied.

In the general formula 8), the substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring represented by Ar ₆₁ may be the same as Ar _{41 in the} general formula (6).

  Although the preferable example of the electron transport material used for the electron carrying layer 6 of the white electroluminescent device of this invention is given to the following, this invention is not limited to these.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a spin coating method, a casting method, a printing method including an ink jet method, an LB method, and the like, preferably It can be formed by a wet process using a coating solution containing an electron transport material and a fluorinated alcohol solvent.

  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.

  Alternatively, an electron transport layer with high n property doped with impurities as a guest material can 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.

  The electron transport layer in the present invention preferably contains an organic alkali metal salt. There are no particular restrictions on the type of organic substance, but formate, acetate, propionic acid, butyrate, valerate, caproate, enanthate, caprylate, oxalate, malonate, succinate Benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate , Preferably formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate, more preferably Is preferably an alkali metal salt of an aliphatic carboxylic acid such as formate, acetate, propionate or butyrate, and the aliphatic carboxylic acid preferably has 4 or less carbon atoms. Most preferred is acetate.

  The type of alkali metal of the alkali metal salt of the organic substance is not particularly limited, and examples thereof include Na, K, and Cs, preferably K, Cs, and more preferably Cs. Examples of the alkali metal salt of the organic substance include a combination of the organic substance and the alkali metal, preferably, formic acid Li, formic acid K, formic acid Na, formic acid Cs, acetic acid Li, acetic acid K, Na acetate, acetic acid Cs, propionic acid Li, Propionic acid Na, propionic acid K, propionic acid Cs, oxalic acid Li, oxalic acid Na, oxalic acid K, oxalic acid Cs, malonic acid Li, malonic acid Na, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, more preferably Li acetate, K acetate, Na acetate, Cs acetate, most preferably Cs acetate.

  The content of these dope materials is preferably 1.5 to 35% by mass, more preferably 3 to 25% by mass, and most preferably 5 to 15% by mass with respect to the electron transport layer to be added.

<< Anode 2 >>
As the anode constituting the white electroluminescent device, an electrode material made of a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode substances 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 desired shape pattern may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. 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 in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.

<< Cathode 8 >>
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 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 metal with a film thickness of 1 to 20 nm on the cathode, a transparent or semitransparent cathode can be produced by forming the conductive transparent material mentioned in the explanation of the anode on the cathode, By applying this, an organic EL element in which both the anode and the cathode are transmissive can be produced.

<Supporting substrate 1>
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the white electroluminescent device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. Or opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. Since the effect of suppressing high-temperature storage stability and chromaticity variation appears greatly in a flexible substrate rather than a rigid substrate, a particularly preferable support substrate has flexibility that can give flexibility to an electroluminescent device. Resin film.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, 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 film, an organic film, or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and more preferably oxygen permeability measured by a method according to JIS K 7126-1987. The film is preferably a high barrier film having a degree of 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less and a water vapor transmission rate of 10 ⁻³ g / (m ² · 24 h) or less. More preferably, the degree is 10 ⁻⁵ g / (m ² · 24 h) or less.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of factors that cause deterioration of the organic EL element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. Can do. 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 order of an inorganic layer and an organic functional layer, It is preferable to laminate | stack both alternately several times.

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

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

<< Sealing (sealing adhesive 9, sealing member 10) >>
As a sealing means applicable to the white electroluminescence device of the present invention, for example, a method of adhering a sealing member, an electrode, and a support substrate with an adhesive can be mentioned.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an electroluminescent device may be covered, and concave plate shape or flat plate shape may be sufficient. Further, 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, silicone, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, and conforms to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by the above method is preferably 1 × 10 ⁻³ g / (m ² · 24 h) or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. 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 electroluminescent device may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. Further, 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 like screen printing.

  It is also preferable that the electrode and the organic functional layer are coated on the outside of the electrode facing the support substrate with the organic functional layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. Can be. 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, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the electroluminescent device, an inert gas such as nitrogen or argon, an inert gas such as fluorinated hydrocarbon or silicon oil is used for the purpose of forming a gas phase and a liquid phase. It is preferable to inject a liquid. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

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

  Sealing includes casing type sealing (can sealing) and close contact type sealing (solid sealing), but solid sealing is preferable from the viewpoint of thinning. Moreover, when producing a flexible electroluminescent device, since a sealing member also needs flexibility, solid sealing is preferable.

  Below, the preferable aspect in the case of performing solid sealing is demonstrated.

  As the sealing adhesive according to the present invention, a thermosetting adhesive, an ultraviolet curable resin, or the like can be used, but preferably a thermosetting adhesive such as an epoxy resin, an acrylic resin, or a silicone resin, more preferably moisture resistant. It is an epoxy thermosetting adhesive resin that is excellent in water resistance and water resistance and has little shrinkage during curing.

  The water content of the sealing adhesive according to the present invention is preferably 300 ppm or less, more preferably 0.01 to 200 ppm, and most preferably 0.01 to 100 ppm.

  The moisture content referred to in the present invention may be measured by any method. For example, a volumetric moisture meter (Karl Fischer), an infrared moisture meter, a microwave transmission moisture meter, a heat-dry weight method, GC / MS, IR, DSC (Differential Scanning Calorimeter), TDS (Temperature Desorption Analysis) can be mentioned. Further, using a precision moisture meter AVM-3000 (Omnitech) or the like, moisture can be measured from a pressure increase caused by evaporation of moisture, and moisture content of a film or a solid film can be measured.

  In the present invention, the moisture content of the sealing adhesive can be adjusted by, for example, placing it in a nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, and changing the time. Further, it can be dried in a vacuum state of 100 Pa or less while changing the time. Further, the sealing adhesive can be dried only with an adhesive, but can also be placed in advance on the sealing member and dried.

  When close sealing (solid sealing) is performed, as the sealing member, for example, a 50 μm thick PET (polyethylene terephthalate) laminated with an aluminum foil (30 μm thick) is used. Using this as a sealing member, it is uniformly applied to the aluminum surface using a dispenser, a sealing adhesive is placed in advance, the resin substrate 1 and the sealing member 5 are aligned, and then both are crimped ( 0.1-3 MPa) and a temperature of 80-180 ° C. for tight adhesion / bonding (adhesion) for tight sealing (solid sealing).

  The heating or pressure bonding time varies depending on the type, amount, and area of the adhesive, but temporary bonding is performed at a pressure of 0.1 to 3 MPa, and the thermosetting time is within a range of 5 seconds to 10 minutes at a temperature of 80 to 180 ° C. Just choose.

  The use of a heated crimping roll is preferred because it allows simultaneous crimping (temporary bonding) and heating, and also eliminates internal voids.

  As a method for forming the adhesive layer, a coating method such as roll coating, spin coating, screen printing, or spray coating, or a printing method can be used depending on the material.

  As described above, the solid sealing is a form in which there is no space between the sealing member and the electroluminescence device substrate and the resin is cured with a cured resin.

  Examples of the sealing member include metals such as stainless steel, aluminum, and magnesium alloys, polyethylene terephthalate, polycarbonate, polystyrene, nylon, plastics such as polyvinyl chloride, and composites thereof, glass, and the like. In the case of a resin film, a laminate of gas barrier layers such as aluminum, aluminum oxide, silicon oxide, and silicon nitride can be used as in the case of a resin substrate.

The gas barrier layer can be formed by sputtering, vapor deposition or the like on both surfaces or one surface of the sealing member before molding the sealing member, or may be formed on both surfaces or one surface of the sealing member after sealing by a similar method. . Also in this case, the oxygen permeability is 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less, and the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is 1 ×. It is preferably 10 ⁻³ g / (m ² · 24 h) or less.

  The sealing member may be a film laminated with a metal foil such as aluminum. As a method for laminating the polymer film on one side of the metal foil, a generally used laminating machine can be used. As the adhesive, polyurethane-based, polyester-based, epoxy-based, acrylic-based adhesives and the like can be used. You may use a hardening | curing agent together as needed. A hot melt lamination method, an extrusion lamination method and a coextrusion lamination method can also be used, but a dry lamination method is preferred.

  In addition, when the metal foil is formed by sputtering or vapor deposition and is formed from a fluid electrode material such as a conductive paste, it may be produced by a method of forming a metal foil on a polymer film as a base material. Good.

《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 on the side facing the support substrate with the organic functional layer interposed therebetween or on the outer side of the sealing film. In particular, when sealing is performed with a 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.

  In the present invention, it is preferable to have a light extraction member between the flexible support substrate and the anode or at any location on the light emission side from the flexible support substrate.

  Examples of the light extraction member include a prism sheet, a lens sheet, and a diffusion sheet. Moreover, the diffraction grating introduce | transduced in the interface which raise | generates total reflection, or any medium, a diffusion structure, etc. are mentioned.

  In general, in an organic electroluminescence element that emits light from a substrate, a part of the light emitted from the light emitting layer causes total reflection at the interface between the substrate and air, causing a problem of loss of light. In order to solve this problem, the prism surface, lens-like processing is applied to the surface of the substrate, or the prism sheet, the lens sheet and the diffusion sheet are attached to the surface of the substrate, thereby suppressing the total reflection and the light extraction efficiency. To improve.

  In order to increase the light extraction efficiency, a method of introducing a diffraction grating or a method of introducing a diffusion structure in an interface or any medium that causes total reflection is known.

<< Method for Producing White Electroluminescence Device 16 >>
As an example of the method for producing a white electroluminescent device of the present invention, a method for producing a white electroluminescent device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described. .

  First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate by a thin film forming method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, An anode is produced.

  Next, an organic functional layer (organic compound thin film) of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is formed thereon.

  The step of forming the organic functional layer mainly includes: (i) a step of applying and laminating the coating liquid constituting the organic functional layer on the anode of the support substrate; and (ii) a coating liquid after coating and lamination. And drying.

  In the step (i), as a method for forming each layer, as described above, a vapor deposition method, a wet process (for example, spin coating method, casting method, die coating method, blade coating method, roll coating method, ink jet method, printing method, spray coating). Method, curtain coating method, LB method (Langmuir Brodgett method and the like can be used), and at least a layer containing quantum dots is preferably formed by a wet process.

  In the formation of the organic functional layer other than the hole injection layer, a wet process is preferable in the present invention because it is easy to obtain a homogeneous film and it is difficult to generate pinholes. Film formation by a coating method such as a method, a die coating method, a blade coating method, a roll coating method or an ink jet method is preferred.

  Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethylsulfoxide (DMSO) can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  In addition, the preparation step for dissolving or dispersing the organic EL material according to the present invention and the application step until the organic EL material is applied on the substrate are preferably in an inert gas atmosphere. Since the film can be formed without degrading the performance of the organic EL element even if it is not carried out in step 1, it may not necessarily be carried out in an inert gas atmosphere. In this case, the manufacturing cost can be suppressed, which is more preferable.

  In the step (ii), the coated and laminated organic functional layer is dried.

  The term “drying” as used herein refers to a reduction to 0.2% or less when the solvent content of the film immediately after coating is 100%.

  As a means for drying, those generally used can be used, and examples thereof include reduced pressure or pressure drying, heat drying, air drying, IR drying, and electromagnetic wave drying. Of these, heat drying is preferable, the temperature is equal to or higher than the boiling point of the solvent having the lowest boiling point in the organic functional layer coating solvent, and the temperature is lower than (Tg + 20) ° C. of the material having the lowest Tg among Tg of the organic functional layer material Most preferably, it is held at In the present invention, more specifically, it is preferably held and dried at 80 ° C. or higher and 150 ° C. or lower, and more preferably held at 100 ° C. or higher and 130 ° C. or lower and dried.

  The atmosphere when drying the coating liquid after coating / lamination is preferably an atmosphere having a volume concentration of a gas other than the inert gas of 200 ppm or less, but it is not necessarily in an inert gas atmosphere as in the liquid preparation coating process. It may not be necessary. In this case, the manufacturing cost can be suppressed, which is more preferable.

  The inert gas is preferably a rare gas such as nitrogen gas and argon gas, and most preferably nitrogen gas in terms of production cost.

  The coating / laminating and drying steps of these layers may be single wafer manufacturing or line manufacturing. Further, the drying process may be performed while being conveyed on the line, but from the viewpoint of productivity, it may be deposited or rolled in a non-contact manner in a roll form.

  After these layers are dried, 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. By providing, a desired white electroluminescent device can be obtained.

  A white electroluminescence device can be produced by adhering the close-sealing or sealing member, the electrode, and the support substrate with an adhesive after the heat treatment.

<Application>
The white electroluminescence device 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. Furthermore, it can be used in a wide range of applications such as general household appliances that require a display device, but it can be used effectively as a backlight for a liquid crystal display device combined with a color filter, and as a light source for illumination. it can.

  In the white electroluminescent device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

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

( Reference Example 1)
<< Preparation of white electroluminescence device >>
(1) Preparation of Reference Example Sample 1 (1.1) Preparation of Gas Barrier Flexible Film First of polyethylene naphthalate film (Teijin DuPont Film, hereinafter abbreviated as PEN) as the flexible film. An inorganic gas barrier film made of SiOx is continuously formed on a flexible film by using an atmospheric pressure plasma discharge treatment apparatus having a structure described in Japanese Patent Application Laid-Open No. 2004-68143 on the entire surface on the electrode forming side. A gas barrier flexible film formed to have a thickness of 500 nm and having an oxygen permeability of 0.001 ml / (m ² · 24 h · atm) or less and a water vapor permeability of 0.001 g / (m ² · 24 h) or less. Produced.

(Discharge treatment)
FIG. 3 is a schematic view of an atmospheric pressure plasma discharge treatment apparatus. In addition to the plasma discharge processing apparatus and the electric field applying means having two power sources, this atmospheric pressure plasma discharge processing apparatus has a gas supply means and an electrode temperature adjusting means, which are not shown in FIG. The plasma discharge treatment apparatus 30 has a counter electrode composed of a first electrode 31 and a second electrode 32, and the frequency ω ₁ from the first power supply 21 from the first electrode 31 between the counter electrodes. A first high-frequency electric field having electric field strength V ₁ and current I ₁ is applied, and a second high-frequency electric field having frequency ω ₂ , electric field strength V ₂ , and current I ₂ from second power source 22 is applied from second electrode 32. Is applied.

In the atmospheric pressure plasma discharge treatment, the electrode gap between the first electrode 31 and the second electrode 32 is set to 1 mm so as to face each other in parallel, and the first electric field (frequency 5 kHz, electric field strength 8 kV, output density 1 W / cm ² ) and second electric field. (Frequency 13.56 MHz, electric field strength 0.8 kV, output density 10 W / cm ² ) was installed. The power source was used at a continuous mode of 100 kHz.

(1.2) Formation of first electrode layer A 120 nm thick ITO (Indium Tin Oxide) film is formed on the prepared gas barrier flexible film by sputtering and patterned by photolithography. An electrode layer (anode) was formed. The pattern was such that the light emission area was 50 mm square.

(1.3) Formation of hole injection layer The patterned ITO substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. On this substrate, a solution of poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (abbreviated as PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083) diluted to 70% with pure water at 3000 rpm for 30 seconds. After film formation by a spin coating method, the film was dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 30 nm.

(1.4) Formation of hole transport layer This substrate was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and exemplary compound (60) (Mw = 80,000) as the hole transport material was transferred. A solution of 0.5% dissolved in chlorobenzene was formed by spin coating at 1500 rpm for 30 seconds, and then kept at 160 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.

(1.5) Formation of light emitting layer Next, a light emitting layer composition having the following composition and a composition diluted twice with the same solvent were formed by spin coating at 1500 rpm for 30 seconds, and then kept at 120 ° C. for 30 minutes. A light emitting layer having a thickness of 40 nm was formed.

<Light emitting layer composition>
Quantum dot A (manufactured by Evident Technologies) Emission wavelength 490 ± 10 nm Particle diameter 7.2 nm 10 parts by mass Quantum dot B (manufactured by Evident Technologies) Emission wavelength 540 ± 10 nm Particle diameter 7.8 nm 2 parts by mass quantum dot C ( (Evident Technologies Co., Ltd.) Emission wavelength 620 ± 10 nm Particle size 9.6 nm 1 part by mass Toluene 1,000 parts by mass (1.6) Formation of electron transport layer Subsequently, the substrate is exposed to the vacuum deposition apparatus without being exposed to the atmosphere. Attached. Moreover, what put exemplary compound (compound A) in the resistance heating boat made from molybdenum is attached to a vacuum evaporation system, and after reducing the vacuum tank to 4 × 10 ⁻⁵ Pa, the boat is energized and heated to heat the exemplary compound. An electron transport layer having a film thickness of 30 nm was formed on Compound (A) at a rate of 1 nm / second on the light emitting layer.

(1.7) Formation of Electron Injection Layer and Cathode Subsequently, a thin film having a thickness of 1 nm was formed on the electron transport layer at a rate of 0.02 nm / second with sodium fluoride. An electron injection layer having a thickness of 1.5 nm was formed on sodium fluoride at 02 nm / second.

  Subsequently, 100 nm of aluminum was deposited to form a cathode.

(1.8) Sealing and Production of White Electroluminescence Device Subsequently, a sealing member was bonded using a commercially available roll laminating apparatus to produce Reference Example Sample 1 (white electroluminescence device).

  In addition, as a sealing member, a flexible aluminum foil (manufactured by Toyo Aluminum Co., Ltd.), a polyethylene terephthalate (PET) film (12 μm thickness) and an adhesive for dry lamination (two-component reaction type urethane system) Adhesive) laminated (adhesive layer thickness 1.5 μm) was used.

  A thermosetting adhesive was uniformly applied to the aluminum surface as a sealing adhesive with a thickness of 20 μm along the adhesive surface (glossy surface) of the aluminum foil using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Furthermore, it moved to nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, dried for 12 hours or longer, and adjusted the moisture content of the sealing adhesive to 100 ppm or lower.

  As the thermosetting adhesive, an epoxy adhesive mixed with the following (a) to (c) was used.

(A) Bisphenol A diglycidyl ether (DGEBA)
(B) Dicyandiamide (DICY)
(C) Epoxy adduct curing accelerator As described above, the sealing substrate is closely attached and arranged so as to cover the joint between the extraction electrode and the electrode lead so as to be in the form shown in FIG. A reference example sample 1 (white electroluminescence device) was produced by tightly sealing using a roll at a thick deposition condition, a pressure roll temperature of 120 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min. When the element of Reference Example 1 was energized, white light emission was observed.

(2) Preparation of Reference Samples 2 to 21 and Comparative Sample 4
In Reference Example Sample Samples 2 to 21 and Comparative Example Sample 4, white light emitting devices were produced by combining the following quantum dots.

  The quantum dots D to H were synthesized by the method shown below. That is, blue / light-emitting CdZnS / ZnS quantum dots C having a core / shell structure were produced in the following manner in the same manner as in International Publication No. 2008/063652, Examples 5A and 5B.

(Preparation of blue light-emitting CdZnS / ZnS quantum dots D)
(1): Preparation of core (CdZnS) 0.050 grams CdO (99.998 percent purity Alpha) and 0.066 grams of ZnO (purity 99.999% —Sigma Aldrich) were equipped with a condenser. Weighed into a three-necked flask. To this was added 32 ml of 4 ml high tech grade oleic acid (Aldrich) and high tech grade octadecene (ODE) (Aldrich). The contents of the flask were degassed at 80 ° C. for 20 minutes (200 mtorr) in vacuo.

  Separately, 0.035 grams of sulfur (99.999% Strem) was dissolved in 10 milliliters of high-tech grade ODE in a septum-capped vial by stirring and heating at 130 ° C. in an oil bath. Heating was continued under nitrogen after the oil bath temperature was 85 ° C. and the vessel pressure was reduced to 200 mTorr while the sample was heating. After 1 hour, after all the sulfur had dissolved, the sample was cooled to room temperature.

  The contents of the three-necked flask were stirred and heated to 310 ° C. for 20 minutes and then to 290 ° C. under nitrogen until all the oxide was a clear solution. The temperature controller was then set to 300 ° C. and once stabilized at a temperature of 300 ° C., approximately 8.0 milliliters of S in the ODE was rapidly injected. The temperature of the solution dropped to about 270 degrees and returned to 300 ° C. in ˜30 minutes. The reaction was stopped after 5 hours and the contents of the flask were transferred to a degassed vial under nitrogen and transferred to an inert atmosphere box for further purification.

  The core was purified by precipitation as follows. The solution was centrifuged for 5 minutes at 4000 rpm. After centrifugation, the supernatant was poured out while retaining the solid in the centrifuge tube. -10 ml of methanol was added to the tube and then decanted. Anhydrous hexane to 10 milliliters, then added to solids in a centrifuge tube and the tube contents were mixed using a vortex mixer. After mixing, the contents of the tube were centrifuged. The supernatant was transferred to another clean tube and the solid in the tube after centrifugation was discarded. The core was precipitated from the supernatant by adding excess butanol (20-25 milliliters) while stirring. The tube containing the precipitated core was decanted and centrifuged, leaving the precipitated core in the tube. The core was added to the precipitate core, solvate to ~ 7.5 ml anhydrous hexane, and the contents of the tube were filtered through a 0.2 micron filter (the core is in the filtrate).

An aliquot of 2.5 μl of the filtrate was diluted 100-fold with anhydrous hexane, the UV VIS spectrum after dilution was measured, and the absorbance was measured at a wavelength of 350 nm.
Core characterization:
Maximum peak emission 461nm
FWHM = 14nm
Photoluminescence emission quantum yield ~ 17%
(2) Preparation of shell (ZnS) 5 ml of 97% trioctylphosphine and 5 ml of oleylamine (distilled before use) were placed in a four-necked flask equipped with a condenser and a thermocouple. The sample was stirred and degassed at 100 ° C. for ˜1 hour. When nitrogen was introduced into the flask, the temperature of 3.8 ml of anhydrous hexane containing the core (see (1) above) was reduced to 80 ° C., nitrogen gas was added, and the solvent was removed under vacuum for 2 hours. Raise the temperature to 170 ° C. and separate 4 ml containing bis-trimethylsilyl sulfide (92.53 mg) in TOP and 4 ml containing diethylzinc (32.00 mg) in TOP at a rate of 50 microliters / minute. Injected from. It was observed that the solution in the flask developed a bluish color. After the addition was complete, the solution was cloudy. Samples were transferred through a degassed vial into an inert atmosphere box.

  The core containing the ZnS shell was purified by precipitation as follows. The sample was transferred to tube 1 and centrifuged at 4000 rpm for 5 minutes.

Tube 1 (Batch 1):
After centrifugation, the supernatant was poured into the tube 2 (centrifugation tube 2) while keeping the solid in the tube 1 (centrifuge tube 1). -5 ml of anhydrous hexane was added to the solid in tube 1 and the contents were mixed using a vortex mixer. The semiconductor nanocrystals containing the core and the ZnS shell disposed on the core were precipitated by adding excess butanol (20-25 ml) with stirring. The contents of tube 1 were centrifuged. The supernatant was decanted leaving the semiconductor nanocrystals in the centrifuge tube. ˜3 milliliters of anhydrous hexane was added as a solvate, and semiconductor nanocrystals in tube 1 of semiconductor nanocrystals were added. The mixture containing anhydrous hexane and semiconductor nanocrystals was filtered from the centrifuge tube 1 with a 0.2 micron filter (the shelled core is in the filtrate).

Tube 2 (Batch 2):
Excess butanol (20-30) was added to tube 2. Tube 2 was centrifuged at 4000 rpm for 5 minutes. After centrifuging, the supernatant was poured out while keeping the solid in the centrifuge tube. Anhydrous hexane to 5 ml was added to each centrifuge tube to the solid and the contents of each centrifuge tube were mixed using a vortex mixer. The semiconductor nanocrystals containing the core and the ZnS shell disposed on the core were precipitated by adding excess butanol (20-25 ml) with stirring. The contents of the centrifuge tube were centrifuged. The supernatant was decanted leaving the semiconductor nanocrystals in the centrifuge tube. ˜3 ml anhydrous hexane solvate semiconductor nanocrystals were added to any of the semiconductor nanocrystals in the centrifuge tube. The mixture containing anhydrous hexane and semiconductor nanocrystals was filtered through a 0.2 micron filter from both centrifuge tubes (the core with shells (quantum dots) is in the filtrate).
Characterization of core / shell nanocrystals:
Maximum peak emission 463 nm FWHM = 18 nm
Photoluminescence emission quantum yield ~ 100% (batch 1 & 2)
(Preparation of blue light emitting CdZnS / ZnS quantum dots EH)
The core particle system was changed by increasing the amount of core added by the same method, and H was produced from quantum dots D.

  The emission maximum wavelength and PL quantum yield of the obtained quantum dots D to H are shown below.

Other types of quantum dots used in the white electroluminescence device of the present invention are shown below.
Quantum dot I (CTD450 manufactured by Cytodiagnostics Inc.) Emission wavelength 463 nm PLQE 70%
The PLQE of quantum dots A to C was 80% or more.
Quantum dot J emission wavelength 570-575 nm PLQE 55-60%
Quantum dot K (manufactured by Nanoco) Emission wavelength 480 ± 5 nm Particle size 4.4 nm PLQE 30-50%
Green emitting quantum dots J were prepared in the same manner as in Example 10 of International Publication No. 2008/133660, and InP / ZnSe _x S _1-x quantum dots J were prepared.

(Preparation of green emitting InP / ZnSe _x Si _1-x quantum dots J)
5 ml squalane and 5 ml methyl myristate were placed in a container preheated to 100 ° C. and evacuated for 30 minutes. (Four-necked, 50 ml round bottom flask with stir bar, temperature probe and condenser connected to N ₂ / depressurization source (Schren wire). The flask was heated with a mantle heater connected to a digital temperature controller. The solvent was degassed for 1 hour at 75 ° C. and then placed under a nitrogen atmosphere.

  An InP-based solution in n-hexane was prepared in a glove box and poured into a container containing a degassed solvent. The n-hexane was removed in vacuo at 75 ° C. for 1 hour, after which the pot was returned to the nitrogen atmosphere. Zn, Se and S precursor solutions were prepared in a glove box. IMTOP-Se and bis (trimethylsilyl) sulfide were weighed in one vial, filled into a 5 ml syringe and diluted to a total of 2.0 ml with squalane to form a selenide / sulfide precursor solution. The amount corresponding to the calculated amount of diethylzinc was weighed in a vial to form a total of 2.0 ml of squalane and zinc precursor solution and filled into another 5 ml syringe. All of the 77-hexane was removed and the vessel was placed under a nitrogen atmosphere at 75 ° C. The two precursor syringes were removed from the glove box, the tube was connected to a capillary, and loaded into a syringe pump. Both ends of the capillary were set in the flask. The temperature was set to 200 ° C., and when the temperature reached 170 ° C., the precursor solution was injected at a rate of 2 ml / hour. Several minutes later, when the temperature reached 200 ° C., 2 ml of oleylamine was injected into the flask. Once the addition is complete, the shelled nanocrystals are preferably annealed prior to crash-out (eg, precipitation from the reaction mixture). For example, the temperature is set to 150 ° C. and left overnight under a nitrogen atmosphere. The next day, the solution is then evacuated for transport into the glove box and injected into a septum-capped vial.

  Upon cooling, a flocculent, reddish solid precipitates from the red reaction mixture. The reaction mixture was reheated to 70 ° C. and redissolved to form a red homogeneous solution. The mixture formed is diluted with 20 ml of hexane and cooled to a sufficient length for the precipitated solid. After centrifugation at 4000 rpm for 8 minutes, the red supernatant is decanted and the collected reddish solid is washed with 10 ml of hexane and centrifuged again. Decant the supernatant and add to the first fraction. Add 20 ml of n-butanol to the red nanocrystal solution, followed by enough methanol (generally ~ 20 ml) to make the solution turbid. Centrifuge the cloudy solution and decant and discard the supernatant. The remaining reddish solid is dissolved in 5 milliliters of W-hexane and filtered through a 0.2 μm PTFE syringe filter. Optical properties were obtained with dilute hexane solution. In the photophysical spectrum of the obtained quantum dots, the first absorption peak was 540 to 545 nm, the emission peak was FWHM = 50 to 55 nm, 570 to 575 nm, and PLQE was 55 to 55%.

<< Measurement of photoluminescence emission quantum yield >>
The photoluminescence quantum yield (PLQE) was measured by the same method as in the above-mentioned International Publication No. 2008/063652.

  That is, various concentration standards were prepared using diphenylanthracene (DPA) to dissolve cyclohexane DPA in an amount appropriate to prepare the various desired concentrations. The absorbance of each reference was measured at 373 nm and measured after the emission region was excited at 373 nm. For example, a series of standards at various concentrations were prepared and the following absorbance values, 0.135, 0.074, 0.044 and 0.023, were obtained as a reference at 373 nm. The straight line was plotted between the light emission amount and the absorbance for obtaining the slope, and the slope was determined from the straight line. The slope obtained from the linear plot of the four absorbance measurements above was about 73661 units. The measurement was performed with a spectrophotometer of CARY Eclipse (manufactured by Agilent Technologies). The CARY Eclipse settings used when making measurements were as follows. The measurement was performed at room temperature (23 to 25 ° C.).

Data mode fluorescence Scan mode emission X mode wavelength (nm)
Start (nm) 383.00
Stop (nm) 700.00
EX. Wavelength (nm) 373.00
EX. Slit (nm) 2.5
Em. Slit (nm) 2.5
Scan rate (nm / min) 600.00
Data interval (nm) 1.0000
Averaging time (s) 0.1000
Excitation filter auto Emission filter open PMT voltage (V) Medium Spectrum correction OFF
The PLQE of the quantum dot can be obtained by calculation using the following formula.

PLQE = {[maximum peak emission area of quantum dots × 0.90 × (1.375) ² ]} / {[inclination of standard line plot × absorbance of quantum dots at 373 nm × (1.423) ² ]}
Where 0.90 (DPA) is the standard PLQE used, 1.375 is the refractive index of hexane, 1.423 is the refractive index of cyclohexane, and the photoluminescence quantum yield in% is It can be calculated from the PLQE value using an equation.

PLQE% = 100 × PLQE
In the production of Reference Example Sample 1, the light emitting layer was produced by combining the quantum dots in the light emitting layer, the light emitting host and the conductive polymer as an additive with the compositions shown in Tables 2 and 3 below. The values in parentheses () in the column of the added host compound and conductive polymer indicate the respective parts by mass added to the light emitting layer. In Tables 2 and 3, when there were two types of quantum dots, the total amount was not changed, and the mass ratio was 1: 1.

In the following tables, quantum dots A to K are abbreviated as A to K. The PLQE value of the quantum dot is shown in parentheses () following the type of quantum dot.
(3) Preparation of Comparative Example Sample 1 The light emitting layer composition was changed to the following composition. Reference Example except that 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris (1-phenyl-1H-benzimidazole (TPBI: manufactured by Kishida Chemical Co.) was used as the electron transport material component. Same as Sample 1.

<Light emitting layer composition>
Iridium complex A 7.6 parts by mass of iridium complex B 0.1 parts by mass Ir (ppy) ₃ 0.3 parts by mass Host component: PVK 92.0 parts by mass Toluene 1000 parts by mass The following iridium complex A and iridium complex B used the compounds described in JP-A-2003-86376 (paragraph numbers [0039] and [0040], respectively).

(3) Preparation of Comparative Example Sample 2 The light emitting layer composition was changed to the following composition. After filling 200 mg each of a molybdenum resistance heating boat with mCBP (charge transport material A) as a host and blue phosphorescent material A and red phosphorescent material A shown below as phosphorescent materials, the heating boat containing mCBP The boat containing the blue phosphorescent material A and the boat containing the red phosphorescent material A are energized independently to deposit mCBP as the light emitting host and the blue phosphorescent material A and the red phosphorescent material A as the light emitting dopant. The speed was adjusted to 85: 15: 0.5, vapor deposition was performed to a thickness of 30 nm, and a light emitting layer was provided.

After the light emitting layer, Comparative Example Sample 2 was produced in the same manner as Reference Example Sample 1.

  For mCBP (charge transport material A), blue phosphorescent material A, and red phosphorescent material A, the following compounds described in paragraph No. [0077] of JP2011-18887A were used.

(4) Preparation of Comparative Example Sample 3 The light emitting layer composition was changed to the following composition. After 200 mg each of a styryl derivative DPVBi and a fluorescent compound (E1, fluorescence peak wavelength: 565 nm) were filled in a molybdenum resistance heating boat, the heating boat containing DPVBi and the boat containing E1 were energized independently, The deposition rate of DPVBi and E1 was adjusted to be 40: 0.04, vapor deposition was performed to a thickness of 40 nm, and a light emitting layer was provided. After the light emitting layer, Comparative Example Sample 3 was produced in the same manner as Reference Example Sample 1.

  DPVBi and E1 are compounds described in Japanese Patent No. 4255610 (paragraph number [0055]).

<< Evaluation of white electroluminescence device >>
The following evaluations were performed on reference example samples 1 to 21 and comparative example samples 1 to 4.

(1) Measurement of luminous efficiency Each of the produced electroluminescent devices was allowed to emit light at room temperature (about 23 ° C.) under a constant current of ^2.5 mA / cm ² , and the emission luminance L immediately after the start of light emission was measured as spectral emission. It measured using luminance meter CS-2000 (made by Konica Minolta Optics).

  Next, a relative light emission luminance was obtained by setting the light emission luminance of Comparative Example Sample 1 as a comparative example to 1.0, and this was used as a measure of the light emission efficiency (external extraction quantum efficiency). It represents that it is excellent in luminous efficiency, so that a numerical value is large.

(2) Measurement of initial driving voltage For each sample, the emission luminance of each sample was measured at room temperature (about 23 to 25 ° C.) using a spectral radiance meter CS-2000 (manufactured by Konica Minolta Optics). The initial drive voltage at an emission luminance of 1000 cd / m ² was determined. The results obtained are shown in Tables 2 and 3.

In Tables 2 and 3, the initial drive voltage of Comparative Example Sample 1 is 1.00, and the initial drive voltages of Reference Samples 1 to 21 and Comparative Samples 1 to 4 are shown as relative values.

(3) Evaluation of continuous drive stability (lifetime) Each sample is wound around a cylinder with a radius of 5 cm, and then continuously driven in a state in which each sample is bent, and the luminance is measured using the spectral radiance meter CS-2000. The time (LT50) during which the measured luminance was reduced by half was determined. The driving condition was set to a current value of 4000 cd / m ² at the start of continuous driving.

  The light emission luminance of Comparative Example Sample 1 was obtained as a relative value with a time (LT50) 50 until the light emission was half of the initial light emission being 1.00, and this was used as a measure of continuous drive stability. The evaluation results are shown in Tables 2 and 3. In Table 2 and Table 3, it shows that it is excellent in continuous drive stability (long life), so that a numerical value is large.

(4) Chromaticity stability Further, the chromaticity (CIE1931 color system x, y) is obtained from the driving voltage and the spectral distribution characteristic result when the luminance is intermittently measured from the start of continuous driving to LT50, and the amount of each change Asked. A smaller value indicates better chromaticity stability. The results are shown in Tables 2 and 3.

(5) Emission color evaluation Each of the produced samples was energized, and the emitted light was measured with a spectral radiance meter CS-2000 (manufactured by Konica Minolta Optics). The sample of the present invention has three colors, red, green and blue. It was confirmed that white light having a luminescent color was emitted.

The above results are shown in Tables 2 and 3. The following compounds were used in the table.
CBP: 4,4'-N, N'-dicarbazole-diphenyl (manufactured by Tokyo Chemical Industry)
PVK: Poly (n-vinylcarbazole) (manufactured by Tokyo Chemical Industry)
Poly (p-phenylene vinylene): poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene] (manufactured by Sigma-Aldrich)
Polythiophene: Poly (3-hexylthiophene-2,5-diyl) (manufactured by Sigma-Aldrich)
Polyaniline: Polyaniline (emeraldine base) (manufactured by Sigma-Aldrich) Poly (p-phenylene sulfide): Poly (1,4-phenylene sulfide) (manufactured by Sigma-Aldrich)

As shown in Tables 2 and 3, in the reference example samples, the luminous efficiency is high, the driving voltage is low, the life is improved, and the chromaticity is stable. In particular, it can be said that this effect is remarkably exhibited by using a specific host compound whose emission wavelength attributed to the 0-0 transition band is 459 nm or less. Furthermore, it has been found that the above effect is further amplified by doping the light emitting layer with a small amount of a conductive polymer. That is, it can be seen that the excellent quantum confinement effect of the quantum dots is brought out by the interaction of the host molecule and the conductive polymer by appropriate doping. Furthermore, it has been found that white light-emitting elements can be produced with a distribution ratio that can be used in production by combining with an appropriate host compound without causing significant energy transfer as in the case of phosphorescent light-emitting materials known in the past. It was.

(Example 2)
<< Preparation of white electroluminescence device 2 >>
( Preparation of Reference Example Sample 22)
A cathode is provided on the support, and an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode are provided in the reverse order of the configuration of Reference Example 1 (reverse layer). White electroluminescence A device was fabricated. An example of such a reverse layer configuration is shown in FIG.

  A transparent support substrate provided with this ITO transparent electrode after patterning was performed on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm ITO (indium tin oxide) film was formed on a 100 mm × 100 mm × 1.1 mm glass substrate. Ultrasonic cleaning with isopropyl alcohol, drying with dry nitrogen gas, and UV ozone cleaning were performed for 5 minutes. A ZnO electron transport layer was provided on the ITO.

Preparation of the electron transport layer is described in J. Org. Am. Chem. Soc 2010, 132, produced using the method described in PP17381-17383. Specifically, zinc acetate and 2-aminoethanol were reacted in anhydrous MeOH for 24 hours, spin-coated on ITO at 4000 rpm, and baked at 300 ° C. for 5 minutes to prepare a 50 nm ZnO electron transport layer. A light emitting layer having a composition as shown in Table 4 was formed on this ZnO, and then 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was formed by vacuum deposition. Hole transport layer made of (50 nm), hole injection layer made of 1,4,5,8,9,12-hexaazatriphenylenehexacarbonyltolyl (HAT-CN) (15 nm), aluminum (Al) (100 nm) A reference example sample 22 was prepared.

  The non-light emitting surface of each white light emitting device after fabrication is covered with a glass case, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy-based photocurable adhesive (Luxe manufactured by Toagosei Co., Ltd.) is used as a sealing material around. Track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, and sealed, as shown in FIGS. Such a lighting device was formed and evaluated.

  One mode of a lighting apparatus including the white light emitting device of the present invention will be described.

  The non-light emitting surface of the white light emitting device of the present invention is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy photocurable adhesive (LUX TRACK manufactured by Toagosei Co., Ltd.) is used as a sealant around the periphery. LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, and an illumination device as shown in FIGS. Can be formed.

  FIG. 4 shows a schematic diagram of the lighting device. The lighting device 101 is covered with a glass cover 102 (note that the sealing operation with the glass cover is performed in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere. In a glove box (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).

  FIG. 5 shows a cross-sectional view of the lighting device. In FIG. 5, 105 denotes a cathode, 106 denotes a light emitting layer, and 107 denotes a glass substrate with a transparent electrode.

  The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

( Production of Example Samples 24, 26, 29, 31, 32, Reference Example Samples 23, 25, 27, 28, 33, and Comparative Samples 30 to 33 )
In the preparation of Reference Example Sample 22, Example Samples 24, 26, 29, 31, 32, Reference were made in the same manner as Reference Example Sample 22 of Example 2 except that the light emitting layer was formed with the composition shown in Table 4. Example samples 23, 25, 27, 28, and 33 and comparative sample samples 30 to 33 were prepared. () In the column of added host compound and conductive polymer indicates the mass ratio of the added amount to the total mass of the quantum dots in the light emitting layer. In Table 4, when there were two types of quantum dots, the total amount was not changed and the mass ratio was 1: 1.

<< Evaluation of white electroluminescence device >>
For each sample, were each evaluated as follows.

(1) Luminous efficiency About the produced white electroluminescent device, external extraction quantum efficiency (%) when applying a ^2.5 mA / cm2 constant current in 23 degreeC and dry nitrogen gas atmosphere was measured as a measure of luminous efficiency. . Similarly, a spectral radiance meter CS-2000 (manufactured by Konica Minolta Optics) was used for the measurement.

The measurement results of luminous efficiency (external extraction quantum efficiency) in Table 4 were expressed as relative values when the measurement value of Reference Example Sample 22 was 100.

(2) Half-life The half-life was evaluated according to the measurement method shown below.

Each white electroluminescent device was driven at a constant current with a current giving an initial luminance of 1000 cd / m ² , and a time required to be ½ of the initial luminance (500 cd / m ² ) was obtained. The half-life was expressed as a relative value when the reference sample 22 of Example 2 was set to 100.

(3) Initial degradation Initial degradation was evaluated according to the measurement method shown below. When the half-life was measured, the time required for the luminance to reach 90% was measured and used as a measure of initial deterioration. The initial deterioration was expressed as a relative value when the measured value of the reference example sample 22 of Example 2 was set to 100. The initial deterioration was calculated based on the following formula.

Initial deterioration = 100 × (luminance 90% arrival time of white electroluminescence device) / (luminance 90% arrival time of each element)
That is, the smaller the initial deterioration value is, the smaller the initial deterioration is.

(4) Dark spot The light emitting surface when each white electroluminescence device was continuously lit under a constant current condition of ^2.5 mA / cm ² at room temperature was visually evaluated. Each element after 10 hours of continuous lighting was evaluated by the following evaluation criteria by visual evaluation by 10 people extracted at random.

×: When the number of confirmed dark spots is 5 or more Δ: When the number of confirmed dark spots is 1 to 4 ○: When the number of confirmed dark spots is 0 (5) Evaluation of luminescent color Each sample was energized, and the emitted light was measured with a spectral radiance meter CS-2000 (manufactured by Konica Minolta Optics). The sample of the present invention emitted white light consisting of three emission colors of red, green and blue. Confirmed to do.

  The above evaluation results are shown in Table 4.

  From the above results, it is possible to provide a white electroluminescent device with high efficiency, excellent stability and small initial deterioration even in the reverse layer configuration. In particular, in a system using a specific host compound, the quantum dot quantum It can be seen that the confinement effect is fully exhibited.

( Reference Example 3)
<< Preparation of white electroluminescence device >>
Samples obtained by changing the compositions of Example Samples 3, 6, 8, 11, 14, 18, 21 and Comparative Samples 1, 2, 3, and 4 prepared in Reference Example 1 as shown in Table 5, Each solution was prepared once, and a white electroluminescence device was produced 10 times in total. Chromaticity (CIE1931 color system x, y) is obtained from the spectral distribution characteristic result when each of the 10 samples produced is driven at an emission luminance of 1000 cd / m ² , and the chromaticity change from the reference sample produced the first time The results of determining the amount are shown in Table 5.

  The amount of change is an average value of absolute values of the amount of change in the (x, y) coordinates. This value was shown as (| Δx |, | Δy |). Spectral distribution characteristics were measured using the spectral radiance meter CS-2000. The results are shown in Table 5.

From the above results, in the device using the phosphorescent materials of comparison, the energy transfer luminescent material is significant, whereas prone to color shift subtle changes in distribution ratio of the quantum dots, reference example The white electroluminescence device has a very low color shift during continuous production, and exhibits a quantum confinement effect of quantum dots, especially in combination with a specific host, which is highly robust and highly productive. You can say that.

DESCRIPTION OF SYMBOLS 1 Flexible support substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Sealing adhesive 10 Flexible sealing member 11 Quantum dot 15 Organic functional layer 16 White electroluminescence device 30 Plasma discharge treatment apparatus 31 1st electrode 32 2nd electrode 101 Illumination apparatus 102 Glass cover 105 Cathode 106 Light emitting layer 107 Glass substrate with a transparent electrode 108 Nitrogen gas 109 Water capturing agent L Released light

Claims (8)

1. A white electroluminescent device having a reverse layer structure having a light emitting layer sandwiched between an anode and a cathode provided on a support substrate, wherein the light emitting layer is a quantum having a light emission maximum wavelength in a range of 400 to 500 nm. One or more dots (BQD), quantum dots (GYQD) having an emission maximum wavelength in the range of 500 to 580 nm, and quantum dots (ORQD) having an emission maximum wavelength in the range of 580 to 650 nm, respectively The mass ratio of the quantum dots in the light emitting layer satisfies the following formulas (A) and (B), and at least two of the BQD, GYQD, and ORQD have a photoluminescence emission quantum yield of 70% or more. Ah is, furthermore, a white-elect said light emitting layer has a that you containing host compounds represented by the following general formula (1) Luminescence device.
Formula (A) 5.5 ≦ BQD / GYQD ≦ 12.0
Formula (B) 1.0 ≦ GYQD / ORQD ≦ 1.3

(In the formula, X represents NR ′, oxygen atom, sulfur atom, CR′R ″, or SiR′R ″. Y ₁ and y ₂ each represent CR ′ or a nitrogen atom. R ′ and R ″. Each represents a hydrogen atom or a substituent, Ar ₁ and Ar ₂ each represent an aromatic ring, and may be the same or different, and n represents an integer of 0 to 4.) White electroluminescent device of claim 1, emission wavelength attributed to 0-0 transition band in phosphorescence spectrum of said host compound is equal to or less than 459 nm. White electroluminescent device according to claim 1 or 2, wherein X in the general formula (1) is characterized in that it is a NR '. X in the said General formula (1) is an oxygen atom, The white electroluminescent device as described in any one of Claim 1 to 3 characterized by the above-mentioned. White electroluminescent device according to any one of claims 1 to 4, characterized in that it contains a conductive polymer to the light-emitting layer. Average particle diameter, white electroluminescent device according to any one of claims 1 to 5, characterized in that in the range of 1~20nm of the quantum dots. The quantum dot is composed of at least Si, Ge, GaN, GaP, CdS, CdSe, CdTe, InP, InN, ZnS, In ₂ S ₃ , ZnO, CdO, or a mixture thereof. The white electroluminescent device according to any one of 1 to 6 . White electroluminescent device according to any one of claims 1 to 7 in which the molecular weight of the host compound, characterized in that it is in the range of 500 to 1000.

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