JP2012094616A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element with low drive voltage which is high in light extraction efficiency (also, external extraction quantum efficiency) and long in emission lifetime.SOLUTION: An organic electroluminescent element includes, on a substrate: a positive electrode; a negative electrode; and at least one organic-inorganic composite luminescent layer between the positive electrode and the negative electrode. The organic-inorganic composite luminescent layer contains an organic phosphorescent material, an organic support medium and inorganic particles.

Description

  The present invention relates to an organic electroluminescence element.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. As a constituent element of ELD, an inorganic electroluminescence element (hereinafter also referred to as an inorganic EL element) and an organic electroluminescence element (hereinafter also referred to as an organic EL element) can be given.

  Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements. An organic EL element has a structure in which a light emitting layer containing a compound that emits light (an organic compound thin film containing a fluorescent organic compound) is sandwiched between a cathode and an anode. It is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when excitons (excitons) are generated by bonding and the excitons are deactivated.

  Usually, in order to utilize this light emission, at least one of the electrodes sandwiching the organic compound thin film is a transparent electrode such as ITO, and the transparent electrode is further supported by a transparent substrate such as glass.

  Organic EL elements can emit light at a low voltage of several volts to several tens of volts, are self-luminous, have a wide viewing angle, have high visibility, and are thin-film, completely solid elements, saving space. It is attracting attention from the viewpoint of portability.

  However, in organic EL elements for practical use in the future, development of organic EL elements that emit light efficiently and with high luminance with lower power consumption is desired.

  In the development of organic EL devices, fluorescent light emitting materials were initially developed. However, since the generation of excited states and the transition from singlet to triplet occur, a shift to the development of theoretically advantageous phosphorescent materials was made. Have been doing.

  As a conventionally known phosphorescent material, many polymer materials have been generally studied, and many low-molecular phosphorescent materials have been developed.

  The characteristics of the organic EL element using these phosphorescent materials are different from the fluorescent materials, and the phosphorescent materials are generally contained in an amount exceeding 5% by mass of the entire light emitting layer. In contrast to a monochromatic organic EL element, it has become more prominent in an element using a light emitting material of a plurality of colors such as a white light emitting organic EL element.

  In such phosphorescent organic EL devices, it has been a problem to be solved to increase the lifetime of the device, and many materials have been developed so far, but it is still in an insufficient state. Is the current situation.

  In addition, as one of the major problems to be solved in order to improve the performance in the future, the conventional organic EL element has a low light extraction efficiency (ratio of energy that goes out of the substrate to emitted energy). The problem is mentioned.

  That is, the light emission of the light emitting layer of the organic EL element is not directional and dissipates in all directions, so there is a large loss when guiding light forward from the light emitting layer, the light intensity is insufficient, and the display screen is dark There is a problem.

The light emitted from the light emitting layer uses only the light emitted in the forward direction, but the light extraction efficiency (light emission efficiency) in the forward direction derived from multiple reflection based on classical optics is 1 / 2n ² . It can be approximated, and is almost determined by the refractive index n of the light emitting layer.

  If the refractive index of the light emitting layer is about 1.7, the light emission efficiency from the organic EL part is simply about 20%. The remaining light propagates in the area direction of the light emitting layer (spray in the lateral direction) or disappears at the metal electrode facing the transparent electrode with the light emitting layer interposed therebetween (absorption in the backward direction).

  In other words, the organic electroluminescence element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and about 15% to 20% of the light generated in the light emitting layer. Can only take out the light.

  This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.

  Various methods for improving the light extraction efficiency have been studied. For example, colloidal silica or silica aerogel is used as a medium for holding at least one organic light emitting material in the light emitting layer and the organic light emitting material. An organic EL element containing the light-emitting layer and having a refractive index adjusted to 1.10 or more and less than 1.50 (see, for example, Patent Document 1), and as constituent layers, conductive particles, semiconductor fine particles, and insulating fine particles An organic EL light emitting device having a functional layer in which at least one of the above is dispersed and the refractive index is adjusted to be larger than that of the light emitting layer (see, for example, Patent Document 2), and further smaller than the thickness of the light emitting layer An organic EL element (for example, see Patent Document 3) having a luminescent nanoparticle made of a metal coordination compound having a particle size as a luminescent center is known.

  However, the light emitting layer formed using colloidal silica or silica airgel having a high porosity as described in Patent Document 1 has low physical durability (scratches are likely to occur, as a result, In addition, the organic EL element formed using the light emitting layer can achieve high light extraction efficiency, but the light emitting life and driving voltage of the light emitting layer are increased. There was a problem.

  In addition, for the light emitting layer composition containing dispersed semiconductor fine particles or insulating fine particles described in Patent Document 2 and the light emitting layer composition containing light emitting nanoparticles described in Patent Document 3, both of the liquids after preparation There is a problem in stagnation, and the physical durability of the light emitting layer formed using each of the light emitting layer compositions is low. As a result, the organic EL device manufactured using the above light emitting layer composition In either case, the external extraction quantum efficiency (simply referred to as light emission efficiency), which indicates the light extraction efficiency, was insufficient from a practical viewpoint.

JP 2007-266243 A JP 2007-242927 A JP 2008-117828 A

  An object of the present invention is to provide an organic EL device having a low driving voltage, high light extraction efficiency (also referred to as external extraction quantum efficiency), and a long light emission lifetime.

  The object of the present invention has been achieved by the following constitution.

1. In an organic electroluminescence device having an anode and a cathode on a substrate, a light emitting layer between the anode and the cathode, and at least one of the light emitting layers being an organic-inorganic composite light emitting layer,
The organic-inorganic composite light-emitting layer contains an organic phosphorescent light-emitting material, an organic carrier medium, and inorganic particles.

  2. 2. The organic electroluminescence device according to 1 above, wherein the organic carrier medium has a molecular weight of 10,000 or less.

  3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein the organic carrier medium is a host material.

  4). 4. The organic electroluminescence device according to any one of 1 to 3, wherein the inorganic particles have an isoelectric point of less than pH 4 or pH 9.8 or more.

5). The inorganic particles are WO ₃ , Sb ₂ O ₅ , V ₂ O ₅ , SiO ₂ , SiC, Ta ₂ O ₅ , La ₂ O ₃ , NiO, PbO, MgO, BeO, CdO, Cd (OH) ₂ , Co (OH) ₂ , Fe (OH) ₂ , Mg (OH) ₂ , Mn (OH) ₂ , Ni (OH) _2, or inorganic particles having a composition of V ₃ O ₈ 5. The organic electroluminescence device according to 4.

  6). Content of the inorganic particle in the said organic inorganic composite light emitting layer is 0.1 mass%-50 mass%, The organic electroluminescent element of any one of said 1-5 characterized by the above-mentioned.

  7). Any one of the above 1 to 6, wherein the inorganic-inorganic composite functional particle is a combination of the inorganic particle and the organic phosphorescent material, and the organic-inorganic composite functional particle is dispersed in an organic carrier medium. 2. The organic electroluminescence device according to item 1.

  8). The absolute value of ζ (zeta) potential of the organic-inorganic composite functional particle is 10 mV or more, and the organic-inorganic composite functional particle is covalently bonded to the organic phosphorescent material. 8. The organic electroluminescence device according to 7.

  According to the present invention, an organic EL element having a low driving voltage, high light extraction efficiency (also referred to as external extraction quantum efficiency), and a long emission lifetime can be provided.

  In the organic EL device of the present invention, by having the configuration according to any one of claims 1 to 9, the driving voltage is low, the light extraction efficiency (also referred to as external extraction quantum efficiency) is high, and An organic EL element having a long light emission lifetime could be provided.

  Hereinafter, the detail of each component of the organic EL element of this invention is demonstrated sequentially.

<Organic / inorganic composite light-emitting layer>
The organic-inorganic composite light emitting layer according to the present invention will be described.

  The organic EL device of the present invention has at least one organic-inorganic composite light-emitting layer as a light-emitting layer, and the organic-inorganic composite light-emitting layer contains an organic phosphorescent light-emitting material, an organic carrier medium, and inorganic particles. An organic EL element having the effects described in the invention (low driving voltage, high light extraction efficiency (also referred to as external extraction quantum efficiency), and long emission lifetime) could be provided.

(Organic phosphorescent material)
The organic phosphorescent material according to the present invention will be described.

  As the organic phosphorescent light emitting material according to the present invention, a specific example of the phosphorescent light emitting material used for the light emitting layer in the constituent layer of the organic EL element described later can be used.

  Among the phosphorescent materials, a complex compound containing a transition element of Group 8 to Group 10 as a central metal in the periodic table of elements can be preferably used, and more preferably the complex system. Among these compounds, iridium complex compounds, osmium complex compounds, platinum complex compounds) and rare earth complexes are preferred, with iridium complex compounds being particularly preferred.

  An example of a preferred embodiment of the organic phosphorescent light emitting material according to the present invention includes organic / inorganic composite functional particles in which inorganic particles described later and an organic phosphorescent light emitting material (also referred to as a light emitting dopant or simply a dopant) are combined. .

  The content of the organic phosphorescent light emitting material in the organic-inorganic composite light emitting layer according to the present invention is preferably in the range of 0.01% by mass to 50% by mass, and is one of the preferred forms of the organic phosphorescent light emitting material. The content of the organic / inorganic composite functional particles is preferably in the range of 0.1% by mass to 50% by mass, more preferably in the range of 1% by mass to 45% by mass, and particularly preferably 3% by mass. % To 40% by mass.

  The average particle size of the organic / inorganic composite functional particles is preferably in the range of 0.5 nm to 250 nm.

  A general method for synthesizing organic-inorganic composite functional particles, which is a preferred embodiment of the organic phosphorescent material according to the present invention, will be described.

  First, a process of synthesizing organic / inorganic composite functional particles according to the present invention by supporting an organic phosphorescent material on silica particles will be described below.

  In the above general synthesis method, the presence of chloroplatinic acid or the like (catalyst) is a compound having at least one known substituent that can react with the polar group (hydroxyl group or the like) on the surface of inorganic particles (silica or the like). The above compound (A), compound (B) or compound (C) can be obtained by heating in nitrogen (40 ° C. to reflux (reflux)).

  Here, R is a group constituting an organic phosphorescent material, and L is a known divalent linking group (an alkylene group, an alkenylene group, an alkynylene group, an arylene group, a heteroarylene group, etc.) without particular limitation. it can.

  In addition, as an example for enabling the organic phosphorescent light emitting material according to the present invention to react with the polar group on the surface of the above inorganic particles (silica or the like), as shown below, the organic phosphorescent light emitting material represented by R A method in which a vinyl group is introduced into a group constituting, and then an alkoxysilane group is introduced and then bonded to inorganic particles is preferably used. However, the present invention is not limited thereto, and the inorganic particles can be formed by a conventionally known method. It is also possible to combine them.

In the above, R represents a group constituting the organic phosphorescent material, and X _{1 to} X ₃ each represents an alkoxy group, a halogen atom, an alkyl group, an aromatic hydrocarbon group (an aryl group, an aromatic hydrocarbon ring group, etc.). Or at least one of X _{1 to} X ₃ represents an alkoxy group or a halogen atom.

Among these, the most preferable embodiment is that when X _{1 to} X ₃ both represent an alkoxy group (for example, a methoxy group, an ethoxy group, an isopropoxy group, etc.), or X 1 and X 2 both represent a methyl group, and X 3 represents This is the case when representing a hydrogen atom.

When both of X _{1 to} X ₃ represent an alkoxy group, organic-inorganic composite functional particles represented by (C) shown in the above general synthesis method can be obtained.

  Hereinafter, although the organic-inorganic composite functional particle concerning this invention and the synthesis example of this organic-inorganic composite functional particle are shown, this invention is not limited to these.

<< Synthesis of Organic-Inorganic Composite Functional Particle Blue-1 >>
(Step 1): Synthesis of Si-B1 (introducing a trimethoxysilyl group into an organic phosphorescent material)

To 100 ml of Dry-THF, 0.1 mol of Vinyl-B1, 0.1 mol of (CH ₃ O) ₃ SiH and 0.003 mol of chloroplatinic acid as a catalyst were added and refluxed at 40 ° C. for 1 hour in a nitrogen stream. Si-B1 was synthesized.

The obtained compound was identified using ¹ H-NMR and ¹³ C-NMR (DPX-300 (Bruker Avance)).

  (Step 2: Synthesis of Blue-1)

  Blue-1 was synthesized by adding 30 ml of Si-B1 (2 g) and organosilica gel (Tol-St manufactured by Nissan Chemical Co., Ltd.) to 100 ml of toluene, and irradiating with 200 kHz ultrasonic waves at room temperature for 30 minutes.

The obtained compound was identified using ¹ H-NMR and ¹³ C-NMR (DPX-300 (Bruker Avance)).

  Further, Blue-1 (a) and Blue-1 (b) were respectively synthesized in the same manner except that 5 g and 7 g of Si-B1 were used.

  In Example 2 described later, Blue-1 is used for the preparation of the organic / inorganic composite light emitting layer composition G, and Blue-1 (a) is used for the preparation of the organic / inorganic composite light emitting layer composition H. Blue-1 (b) Was used for the preparation of the organic-inorganic composite light-emitting layer composition I.

<< Synthesis of Organic-Inorganic Composite Functional Particles Blue-2 >>
In the synthesis of the organic / inorganic composite functional particle Blue-1, the organic / inorganic composite functional particle Blue-2 was similarly prepared except that the group constituting the organic phosphorescent material represented by R in Si-B1 was changed. Was synthesized.

  << Synthesis of Organic-Inorganic Composite Functional Particles Green-1 and 2 >>

  In the synthesis of the organic / inorganic composite functional particle Blue-1, the organic / inorganic composite functional particle Green-1 was similarly performed except that the group constituting the organic phosphorescent material represented by R in Si-B1 was changed. 2 was synthesized.

  In the synthesis of Green-1 above, materials obtained by synthesizing 2 g, 5 g, and 7 g of Si-B1 in which the portion of the group constituting the organic phosphorescent light emitting material represented by R is synthesized, respectively, −1, Green-1 (a), and Green-1 (b).

  In Example 2 to be described later, Green-1, Green-1 (a), and Green-1 (b) were used for preparation of the organic-inorganic composite light-emitting layer compositions G, H, and I, respectively.

  << Synthesis of Organic-Inorganic Composite Functional Particles Red-1 and 2 >>

  In the synthesis of the above Red-1, those obtained by synthesizing 2 g, 5 g, and 7 g, respectively, of materials in which the part of the group constituting the organic phosphorescent light emitting material represented by R of Si-B1 is changed, respectively. -1, Red-1 (a), Red-1 (b).

  In Example 2 described later, Red-1, Red-1 (a), and Red-1 (b) were used for the preparation of the organic-inorganic composite light-emitting layer compositions G, H, and I, respectively.

  In the synthesis of the organic-inorganic composite functional particle Blue-1, organic-inorganic composite functional particle Red-1 was similarly performed except that the group of the group constituting the organic phosphorescent material represented by R in Si-B1 was changed. 2 was synthesized.

(Molecular weight of organic phosphorescent materials)
The molecular weight of the organic phosphorescent material according to the present invention is preferably less than 3000 from the viewpoint of obtaining a light emitting layer having high light extraction efficiency.

(Definition of molecular weight and measurement method of molecular weight)
The molecular weight definition and molecular weight measurement method according to the present invention includes a low molecular weight compound having no molecular weight distribution, an oligomer or a high molecular compound having a molecular weight distribution (here, a high molecular compound has a weight average molecular weight of 10,000 or more). The definition and measurement method differ depending on

(A) In the case of a low molecular compound having no molecular weight distribution In the case of a low molecular compound having no molecular weight distribution, data obtained by a conventionally known mass spectrometry method (mass spectrum method) is shown.

(B) In the case of an oligomer or polymer compound having a molecular weight distribution On the other hand, in the case of an oligomer or polymer compound having a molecular weight distribution, the weight average molecular weight is used as the molecular weight according to the present invention. The measurement is determined by the GPC method as will be described later.

  The detail of the measurement of the weight average molecular weight of a high molecular compound is shown below.

(Measurement of weight average molecular weight)
The molecular weight (weight average molecular weight (Mw)) of the polymer compound according to the present invention can be measured using GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a column solvent.

  Specifically, 1 ml of THF (using a degassed sample) is added to 1 mg of a measurement sample, and the sample is stirred using a magnetic stirrer at room temperature to be sufficiently dissolved. Subsequently, after processing with a membrane filter having a pore size of 0.45 μm to 0.50 μm, it is injected into a GPC (gel permeation chromatograph) apparatus.

  GPC measurement conditions are measured by stabilizing the column at 40 ° C., flowing THF (tetrahydrofuran) at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml.

  As the column, it is preferable to use a combination of commercially available polystyrene gel columns. For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard, etc. manufactured by Tosoh Corporation A combination of these is preferred.

  As the detector, a refractive index detector (RI detector) or a UV detector is preferably used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points are preferably used as polystyrene for preparing a calibration curve.

  In the present invention, the molecular weight was measured under the following measurement conditions.

(Measurement condition)
Equipment: Tosoh High Speed GPC Equipment HLC-8220GPC
Column: TOSOH TSKgel Super HM-M
Detector: RI and / or UV
Eluent flow rate: 0.6 ml / min Sample concentration: 0.1% by mass
Sample volume: 100 μl
Calibration curve: Prepared with standard polystyrene: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 10000 to 500,000 was used to create a calibration curve (also referred to as calibration curve) and used to calculate molecular weight . It is preferable that the 13 samples are substantially equally spaced.

(Organic support medium)
The organic carrier medium according to the present invention will be described.

  The organic supporting medium according to the present invention is a medium that supports the constituent material of the organic-inorganic composite light emitting layer (for example, organic phosphorescent light emitting material, inorganic particles, etc.). Host materials, light-emitting hosts, and the like) and conventionally known polymer materials (also referred to as organic resins and resins) can be used. Of these, host compounds are preferable.

  Among host compounds and polymer materials, a host compound having a high Tg (glass transition point) and an organic resin having a high Tg (glass transition point) are preferable.

  As a specific example of the host compound, a host compound (host material, light-emitting host, etc.) described in the light-emitting layer according to the constituent layer of the organic EL element described later can be used.

  Examples of the polymer material used as the organic support medium according to the present invention include acrylic polymer, polyvinyl butyral resin, polyurethane resin, polyamide resin, polyester resin, epoxy resin, phenol resin, polycarbonate resin, polyvinyl formal resin, shellac, and cellulose. Series resins and other conventionally known natural resins can be used.

  Note that the above polymer materials may be used alone or in combination.

  Furthermore, as a polymer material, an engineering plastic is preferable as a resin having a high Tg (glass transition point). Specifically, the following resins or derivatives of those resins may be used alone or in combination of two or more. Is preferred.

  Specifically, polyacetal (POM), polyamide (PA), polycarbonate (PC), modified polyphenylene ether (m-PPE), polybutylene terephthalate (PBT), GF reinforced polyethylene terephthalate (GF-PET), ultrahigh molecular weight polyethylene (UHPE), syndiotactic polystyrene (SPS), amorphous polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyimide ( PI), polyetherimide (PEI), fluororesin, liquid crystal polymer (LCP) and the like.

(Molecular weight of organic carrier medium)
The molecular weight of the organic carrier medium according to the present invention is preferably 10,000 or less from the viewpoint of obtaining a light emitting layer with high light extraction efficiency.

  The molecular weight of 10,000 or less according to the present invention indicates data obtained by a conventionally known mass spectrometry method (mass spectrum method) in the case of a low molecular compound having no molecular weight distribution.

  On the other hand, in the case of a compound having a molecular weight distribution such as a polymer compound, the weight average molecular weight is used as the molecular weight, but the details of the measurement of the weight average molecular weight are the same as those described in the organic phosphorescent light emitting material. It is.

(Inorganic particles)
The inorganic particles according to the present invention will be described.

  By including the inorganic particles according to the present invention in the organic carrier medium together with the organic phosphorescent light emitting material, external extraction quantum efficiency (simply referred to as light extraction efficiency or light emission efficiency) is improved, and Thus, an element that can be driven at a low voltage was obtained.

  As a reason for this, the present inventors have greatly improved the dispersibility of the organic phosphorescent light-emitting material by coordinating in the vicinity of the inorganic particles due to the surface charge of the inorganic particles, and as a result, It is presumed that the light emission efficiency is improved and, at the same time, deterioration over time such as aggregation and recrystallization in the light emitting layer of the organic phosphorescent light emitting material is effectively prevented.

  Moreover, as a preferable physical property of the inorganic particles according to the present invention, those having an isoelectric point of less than pH 4 or more than pH 10 are preferable.

  Furthermore, the content of inorganic particles in the organic-inorganic composite light-emitting layer is preferably in the range of 0.1% by volume to 50% by volume.

  Hereinafter, although the specific example (name of an inorganic compound and isoelectric point) of the inorganic particle which concerns on this invention is shown, this invention is not limited to these. Of the inorganic particles shown below, those having an isoelectric point of less than pH 4 or more than pH 10 are preferably used.

Name of inorganic compound Isoelectric point (pH)
Tungsten (VI) oxide WO ₃ 0.2-0.5
Sb ₂ O ₅ 0.4 to 1.9 of oxide of antimony (V)
Vanadium (V) oxide V ₂ O ₅ 1-2
Silicon oxide (anhydrous silicic _acid) SiO 2 _1.7~3.5
Silicon carbide (alpha) SiC 2-3.5
Tantalum (V) oxide, Ta ₂ O ₅ 2.7-3.0
Tin (IV) oxide SnO ₂ 4 to 5.5
Zirconium (IV) Oxide ZrO ₂ 4-11
Manganese (IV) oxide MnO ₂ 4-5
Delta MnO ₂ 1.5
Beta MnO ₂ 7.3
Titanium (IV) oxide (titania)
(Rutile or _anatase) TiO 2 3.9~8.2
Silicon nitride Si ₃ N ₄ 6-7
Iron (II, III) oxide (magnetite) Fe ₃ O ₄ 6.5-6.8
Oxide of gamma iron (III) Fe ₂ O ₃ 3.3-6.7
(IV) oxide cerium _(ceria) CeO 2 _6.7~8.6
Chromium (III) oxide (chromia) Cr ₂ O ₃ 6.2-8.1
Gamma aluminum oxide (gamma alumina) Al ₂ O ₃ 7-8
Thallium (I) oxide TL ₂ O 8
Alpha Iron (III) Oxide (Hematite) Fe ₂ O ₃ 8.4-8.5
Aluminum oxide (alpha alumina, cobblestone) Al ₂ O ₃ 8-9
Silicon nitride Si ₃ N ₄ 9
Yttrium (III) oxide _(yttria) Y ₂ O 3 7.15~8.95
Copper (II) oxide CuO 9.5
Zinc oxide ZnO 8.7 to 10.3
Lanthanum (III) oxide La ₂ O ₃ 10
Nickel (II) oxide NiO 9.9 to 11.3
Lead (II) oxide PbO 10.7 to 11.6
Magnesium oxide (magnesia) MgO 9.8 to 12.7
For the above inorganic particles and isoelectric point,
Marek Kosmulski, “Chemical Properties of Material Surfaces”, Marcel Dekker, 2001. The description of was quoted.

However, only for the tin (IV) oxide SnO ₂ ,
Kosmulski M and Saneluta C (2004). 'Point of zero charge / isoelectric point of exotic oxides: Tl ₂ O ₃ ', Journal of Colloid and Interface Science vol. 280, no. 2, pp. 544-545. The description of was quoted.

  Although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.

Note that the isoelectric points of hydroxides such as Cd (OH) ₂ , Fe (OH) ₂ , Mg (OH) ₂ , and Ni (OH) ₂ are defined to be the same as the isoelectric points of the corresponding oxides. .

(Average primary particle size of inorganic particles)
The average primary particle size of the inorganic particles according to the present invention is preferably adjusted in the range of 0.1 nm to 30 nm, more preferably in the range of 0.1 nm to 20 nm, and particularly preferably in the range of 1 nm to 10 nm. It is a range.

  Moreover, the average primary particle diameter of the inorganic particles according to the present invention can be measured using, for example, a particle diameter measuring device DLS-7000 (manufactured by Otsuka Electronics Co., Ltd.).

<< Constituent layers of organic EL elements >>
(I) Anode / hole injection layer / light emitting layer / electron injection layer / cathode (ii) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode (iii) Anode / hole injection layer / Hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode At least one of the “light emitting layer” includes the organic / inorganic composite light emitting layer according to the present invention, and other than the organic / inorganic composite light emitting layer. A conventionally known light emitting layer may be used in combination.

<< Injection layer: hole injection layer, electron injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

  The injection layer is a layer provided between the electrode and the organic layer for lowering the driving voltage and improving the light emission luminance. “Organic EL element and its forefront of industrialization (published by NTT Corporation on November 30, 1998)” Part 2 Chapter 2 “Electrode Materials” (pages 123 to 166) in detail, there are a hole injection layer and an electron injection layer.

  The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like, and the hole injection material of the present invention includes a triazole derivative. , 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, silazane derivatives, etc. Or an aniline copolymer, a polyarylalkane derivative, or a conductive polymer, preferably a polythiophene derivative, a polyaniline derivative, a polypyrrole derivative, and more preferably a polythiophene derivative.

  The details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specifically, metals represented by strontium, aluminum and the like. Examples thereof include a 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. The buffer layer (injection layer) is desirably a very thin film, although depending on the material, the film thickness is about 0.1 nm to 5 μm, preferably 0.1 nm to 100 nm, more preferably 0.5 nm to 10 nm, Most preferably, it is 0.5 nm-4 nm.

《Hole transport layer》
Although the thing of the said hole injection layer can be used as a hole transport material, Furthermore, using a porphyrin compound, an aromatic tertiary amine compound, and a styryl amine compound, especially an aromatic tertiary amine compound is used. Is preferred.

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

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

  Conventionally, 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 light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, the material can be selected and used from among conventionally known compounds, such as nitro-substituted fluorene derivatives, dibenzofuran derivatives, Examples include diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like.

  Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  In addition, 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.

Metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq) ₃ , tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.

  In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

  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, or an LB method. About the film thickness of an electron carrying layer, the range of 5 nm-5 micrometers is preferable, More preferably, it is the range of 5 nm-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

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

<Light emitting layer>
The light emitting layer according to the present invention will be described.

  As described in 1 above, the organic EL device of the present invention is characterized in that at least one of the light emitting layers is an organic / inorganic composite light emitting layer and contains an organic phosphorescent light emitting material, an organic carrier medium and inorganic particles. And

  In addition to the organic-inorganic composite light-emitting layer, the light-emitting layer according to the organic EL device of the present invention may further include a light-emitting layer described in a conventionally known document. A phosphorescent material can be used.

  The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

  The 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.

  Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. It is preferable to have a non-light emitting intermediate layer between each light emitting layer.

  The total thickness of the light emitting layers according to the present invention is preferably in the range of 1 nm to 100 nm, and more preferably 50 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.

  The film thickness of each light emitting layer is preferably adjusted in the range of 1 nm to 50 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

  For the production of the light emitting layer, a light emitting 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, a plurality of light emitting materials may be mixed in each light emitting layer, and a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.

  In the present invention, the structure of the light-emitting layer preferably contains a host compound and a light-emitting material (also referred to as a light-emitting dopant compound) and emits light from the light-emitting material.

(Host compound (also called host material, luminescent host, etc.))
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, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.

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

  As the known host compound, a compound having a hole transporting ability and an electron transporting ability, preventing an increase in the wavelength of light emission, and having a high Tg (glass transition temperature) is preferable. 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 the host compound preferably used in the present invention are listed below, but the present invention is not limited to these.

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

(Luminescent material)
Next, the light emitting material will be described.

  As described in 1 above, the organic EL device of the present invention has at least one organic-inorganic composite light-emitting layer as a light-emitting layer, and the organic-inorganic composite light-emitting layer has at least one organic phosphorescent light-emitting material as a light-emitting material. Contained.

  The organic EL device of the present invention may have a conventionally known light emitting layer in addition to the organic-inorganic composite light emitting layer as the light emitting layer. The light emitting material contained in the light emitting layer may be fluorescent. A compound or an organic phosphorescent material (also referred to as a phosphorescent compound or a phosphorescent compound) can be used, but an organic phosphorescent material is preferable.

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

  The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. The phosphorescence quantum yield in a solution can be measured using various solvents. However, when a phosphorescent material is used in the present invention, the phosphorescence quantum yield (0.01 or more) is achieved in any solvent. Just do it.

  There are two types of light emission of the phosphorescent material. In principle, the carrier recombination occurs on the host compound to which the carrier is transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent material. Energy transfer type to obtain light emission from the phosphorescent light emitting material, and another one is that the phosphorescent light emitting material becomes a carrier trap, and recombination of carriers occurs on the phosphorescent light emitting material, and light emission from the phosphorescent light emitting material is obtained. Although it is a trap type, in any case, the excited state energy of the phosphorescent material is required to be lower than the excited state energy of the host compound.

  The organic phosphorescent light-emitting material according to the present invention can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, but is preferably a Group 8 to Group 10 metal in the element periodic table. More preferred are iridium compounds, osmium compounds, platinum compounds (platinum complex compounds), and rare earth complexes, and most preferred are iridium compounds.

  Specific examples of the compound used as the organic phosphorescent material according to the present invention are shown below, but the present invention is not limited thereto. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, etc.

  For the organic EL device of the present invention, a fluorescent light emitter can also be used. Typical examples of fluorescent emitters (fluorescent dopants) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Examples thereof include dyes, perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

  Conventionally known dopants can also be used in the present invention. For example, International Publication No. 00/70655, JP-A Nos. 2002-280178, 2001-181616, 2002-280179, 2001- No. 181717, No. 2002-280180, No. 2001-247859, No. 2002-299060, No. 2001-313178, No. 2002-302671, No. 2001-345183, No. 2002-324679. Publication No. WO 02/15645, JP 2002-332291 A, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572 A, JP No. 2002-117978 No. 2002-338588, No. 2002-170684, No. 2002-352960, No. WO 01/93642, JP-A No. 2002-50483, No. 2002-1000047, No. 2002-173684. Gazette, 2002-359082 gazette, 2002-17584 gazette, 2002-363552 gazette, 2002-184582 gazette, 2003-7469 gazette, 2002-525808 gazette, JP2003-7471 gazette. Gazette, Japanese translations of PCT publication No. 2002-525833, JP-A-2003-31366, JP-A-2002-226495, JP-A-2002-234894, JP-A-2002-235076, JP-A-2002-241751, JP-A-2001-2001. 319779 Broadcast, the 2001-319780, JP same 2002-62824, JP same 2002-100474, JP same 2002-203679, JP same 2002-343572 and JP Laid Nos. 2002-203678 and the like.

  In the present invention, at least one light emitting layer may contain two or more kinds of light emitting materials, and the concentration ratio of the light emitting materials in the light emitting layer may vary in the thickness direction of the light emitting layer.

《Middle layer》
In the present invention, a case where a non-light emitting intermediate layer (also referred to as an undoped region) is provided between the light emitting layers will be described.

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

  The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 nm to 20 nm, and further in the range of 3 nm to 10 nm suppresses interaction such as energy transfer between adjacent light emitting layers, and This is preferable because a large load is not applied to the current-voltage characteristics.

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

  The non-light-emitting intermediate layer may contain a non-light-emitting layer, a compound common to each light-emitting layer (for example, a host compound), and each common host material (where a common host material is used) In the case where the physicochemical characteristics such as phosphorescence emission energy and glass transition point are the same, or the molecular structure of the host compound is the same, etc.) The barrier is reduced, and the effect of easily maintaining the injection balance of holes and electrons even when the voltage (current) is changed can be obtained.

  Furthermore, by using a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer, device fabrication, which is a major problem in conventional organic EL device fabrication, is achieved. Complexity can also be eliminated.

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

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

  Hereinafter, although the preferable specific example of the compound used for the hole transport material, electron transport material, etc. of the organic EL element of this invention is given, this invention is not limited to these.

  (Hole transport material)

  In addition, said n represents a polymerization degree and represents the integer from which the weight average molecular weight becomes the range of 50,000-200,000. 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 life of the organic EL element deteriorate.

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

  (Electron transport material)

  These compounds are disclosed in JP 2007-288035 A, Chem. Mater. , 2008, 20, 5951, Experimental Chemistry Course 5th Edition (Edited by the Chemical Society of Japan), etc.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO.

Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when 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 preferably in the range of 10 nm to 1000 nm, more preferably in the range of 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.

Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.

  The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually preferably in the range of 10 nm to 5 μm, more preferably in the range of 50 nm to 200 nm.

  In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque.

  When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. Since the effect of the film-enhancing functional layer appears greatly with a flexible substrate rather than a rigid substrate, a particularly preferable support substrate is a resin film that can give flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. And a relative humidity (90 ± 2)% RH) of 0.01 g / (m ² · 24 h) or less is preferable.

Moreover, the oxygen permeability measured by the method according to JIS K 7126-1987 is 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, and the water vapor permeability is 10 ⁻³ g / (m ² · 24 h). The following high-barrier film is preferable, and the water vapor permeability is more preferably 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 elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used.

  Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  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.

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more.

  Here, the external extraction quantum efficiency is defined as follows.

External extraction quantum efficiency (%) = number of photons emitted to the outside of the organic EL element / number of electrons sent to the organic EL element × 100
In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element 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, silicon, 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 photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

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

  In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.

  Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster-ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. 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.

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

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be extracted outside the device, This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

  As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method of improving efficiency by providing a light collecting property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

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

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

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

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

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

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

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

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

  As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

  At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention is processed on the light extraction side of the substrate so as to provide, for example, a microlens array structure, or combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the device light emitting surface. By condensing in the front direction, the luminance in a specific direction can be increased.

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

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

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

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / 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 so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm, to form an anode.

  Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

  As a method for forming each of these layers, there are a vapor deposition method, a wet process (spin coating method, a cast method, an ink jet method, a printing method) and the like as described above, but the hole injection layer used in the present invention is a wet process (wet process). (Also referred to as).

  Even in the formation of functional layers other than the hole injection layer, a wet process (wet process) is preferable in the present invention from the viewpoint that a homogeneous film is easily obtained and pinholes are not easily generated. Film formation by a coating method such as a method, an ink jet method, or a printing method is preferably used.

  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 DMF and 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.

  After these layers are formed, a thin film made of a cathode material is formed thereon by 1 μm or less, preferably by a method such as vapor deposition or sputtering so that the film thickness is in the range of 50 nm to 200 nm. By providing, a desired organic EL element can be obtained.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order.

  When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 V to 40 V with the anode as + and the cathode as-polarity. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. 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 organic EL element 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, although an Example demonstrates this invention, this invention is not limited to these. Moreover, the structure of the compound used in the Example is shown below. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

Example 1
<< Preparation of Light-Emitting Layer Composition 1 and Organic-Inorganic Composite Light-Emitting Layer Compositions A to E >>
(Light-Emitting Layer Composition 1): For Light-Emitting Layer Preparation of Comparative Organic EL Element 1 Host-25 22.5 parts by mass D-28 2.4 parts by mass Ir-1 0.05 parts by mass Ir-14 0.05 parts by mass Parts isopropyl acetate 2,000 parts by mass (organic-inorganic composite light-emitting layer compositions A to E)
Host-25 21.75 parts by weight Inorganic particles (described in Table 1) 0.75 parts by weight D-28 2.4 parts by weight Ir-1 0.05 parts by weight Ir-14 0.05 parts by weight Isopropyl acetate 2,000 Part by mass The details of silica, γ-alumina, titanium oxide, tungsten oxide, and magnesium oxide listed in Table 1 are shown below.

Organosilica: NBac-ST manufactured by Nissan Chemical Co., Ltd.
Alumina: CIK Nanotech ALPA 15% by mass X480
Titanium oxide: CIK Nanotech TIPA 15% by mass X480
Tungsten oxide: Beckman Coulter Butan-1-ol Magnesium oxide: Ube Material Prior to the evaluation of the organic EL elements 1 to 6, the light emitting layer composition used for the preparation of each light emitting layer of the organic EL elements 1 to 6 1. Using each of the organic-inorganic composite light-emitting layer compositions A to E, the liquid stagnation of the composition, the scratch rank evaluation (physical durability) of the light-emitting layer alone produced using the composition, Refractive index and the like were evaluated.

  Further, the ζ potential and isoelectric point of the inorganic particles used for the production of the light emitting layer were measured as follows.

(Evaluation of light emitting layer composition)
In the production of the organic EL elements 1 to 6, the light-emitting layer composition used for the production of the light-emitting layer is liquid stagnation, the light-emitting layer alone scratch rank obtained using the light-emitting layer composition as described below, light emission The refractive index of the layer alone was evaluated.

(Liquid stagnation)
The prepared light emitting layer coating solution was allowed to stand for 1 week in an environment of 23 ° C. and 50% RH, and the deposits of the solution after standing were visually evaluated. About the thing which could confirm precipitation, it filtered and calculated the precipitation rate. : No precipitate at all: Very slight precipitation (less than 5% of dissolved amount): Precipitated (5-20% of dissolved amount) x: Vigorous precipitation (20% or more)
(Scratch rank of light emitting layer)
A light emitting layer coating solution was formed on quartz glass by spin coating at 1500 rpm for 30 seconds, and then held at 120 ° C. for 30 minutes to form a light emitting layer having a thickness of 50 nm. The prepared film was subjected to a continuous load test with a 0.3 mmR sapphire needle with a scratch tester (manufactured by HEIDON), and ranked according to the average load at which the film was peeled off from quartz.

◎: No damage at 100 g. ○: Less than 20% at 100 g. △: 80-100 g
Δ: 50-80g
Δ ×: 20-50 g
X: Less than 20 g (refractive index of light emitting layer)
In the same manner as described above, a light emitting layer coating solution was formed on quartz glass by spin coating at 1500 rpm for 30 seconds, then held at 120 ° C. for 30 minutes to form a light emitting layer with a thickness of 50 nm, and measured with an existing ellipsometer I asked.

  In addition, it is confirmed separately that the single light emitting layer formed by applying only the light emitting layer composition on the substrate and the light emitting layer formed as one of the constituent layers of the organic EL element described later have the same refractive index. It is done.

(Zeta potential, isoelectric point)
The zeta potential referred to in the present application was measured with a mixed solution in which the inorganic particle dispersion was diluted to 5% by mass with a 1: 1 mixed solution of isopropyl alcohol and methanol.

  An ultrasonic particle size distribution / zeta potential measuring device DT-1200 (Dispersion Technology, USA) was used.

  For each of the light emitting layer composition 1 and the organic / inorganic composite light emitting layer compositions A to E, the constituent material of the light emitting layer, presence or absence of inorganic particles, isoelectric point, ζ potential, refractive index of the produced light emitting layer, scratch rank, liquid Table 1 shows the results of stagnation.

<< Preparation of Organic EL Element 1-1 >>: Comparative Example After patterning a substrate (NH Techno Glass Co., Ltd .: NA-45) on which 100 nm of ITO was formed on glass as an anode, this ITO transparent electrode was provided. The transparent support substrate was ultrasonically cleaned with iso-propyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes to produce an anode (also referred to as a first electrode).

  On the obtained anode, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P AI 4083) to 50% with pure water at 3000 rpm for 30 seconds. After forming the film by spin coating, the film was held at 150 ° C. for 30 minutes to provide a hole injection layer having a thickness of 60 nm.

  This substrate was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and a solution obtained by dissolving 0.5% by mass of the exemplified hole transport material (8) (Mw = 80,000) in chlorobenzene was 1500 rpm for 30 seconds. After forming the film by spin coating, the film was held at 160 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.

  Furthermore, after forming the light emitting layer composition 1 prepared above by a spin coat method at 1500 rpm for 30 seconds, the light emitting layer having a film thickness of 50 nm was formed by holding at 120 ° C. for 30 minutes.

  Subsequently, a solution obtained by dissolving 30 mg of ET-A in 4 ml of tetrafluoropropanol (TFPO) was applied and formed into a film using a spin coating method at 1500 rpm for 30 seconds, and maintained at 120 ° C. for 30 minutes. A 30 nm electron transport layer was prepared.

Subsequently, the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Further, a molybdenum resistance heating boat with KF added thereto is attached to a vacuum deposition apparatus, and after the vacuum tank is depressurized to 4 × 10 ⁻⁵ Pa, the boat is energized and heated to KF of 0.02 nm / second. To deposit an electron injecting layer having a thickness of 2 nm. Subsequently, 100 nm of aluminum was deposited to form a cathode.

(Sealing (sealing treatment of organic EL element))
An aluminum foil with a thickness of 100 μm was prepared as a barrier layer, and a thermosetting liquid adhesive (epoxy resin) was applied with a thickness of 30 μm on one surface of the aluminum foil to obtain a sealing member.

  The adhesive surface of the sealing member and the organic layer surface of the element are overlapped so that the end of the extraction electrode of the anode (also referred to as the first electrode) and the cathode (also referred to as the second electrode) of the organic EL element is exposed. Adhesion was performed by a dry laminating method. Organic EL element 1 (comparative example) was produced.

<< Preparation of Organic EL Elements 2-6 >>: Present Invention In the preparation of the organic EL element 1 (comparative example), each of the organic-inorganic composite light-emitting layer compositions A to E was changed in place of the light-emitting layer composition 1. The organic EL elements 2 to 6 were prepared in the same manner except that the composition was prepared, heated at 85 ° C. under sealing, left for 10 minutes, irradiated with 20 kHz ultrasonic waves for 5 minutes, and then irradiated with 1 MHz ultrasonic waves for 5 minutes. Each was produced.

(Drive voltage)
The organic EL element was turned on at room temperature (about 23 ° C. to 25 ° C.) under a constant luminance condition of 1,000 cd / m ² , and the drive voltage immediately after the start of lighting was measured.

(Luminescent life)
The organic EL element was continuously lit at room temperature under a constant current condition with a current having an initial luminance of 1,000 cd / m ^2, and a time (τ1 / 2) until the luminance became half of the initial luminance was measured.

  The light emission lifetime was expressed as a relative value with the light emission lifetime of the organic EL element 1 (comparative example) as 100 (%).

(External quantum efficiency)
With respect to the produced organic EL element, the external extraction quantum efficiency (%) when a constant current of ^2.5 mA / cm ² was passed was measured under an inert gas atmosphere. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used. The obtained result was expressed as a relative value when the measured value of the organic EL element 1 (comparison) was 100 (%).

  The evaluation results for the organic EL elements 1 to 6 are shown in Table 2 below.

  From Table 2, compared with the comparative organic EL element 1, the organic EL elements 2 to 6 of the present invention are excellent in all the characteristics of life (light emission life), efficiency (light emission efficiency), and voltage (drive voltage). It is clear.

Example 2
<< Preparation of Luminescent Layer Composition 2 >>
In the preparation of the light-emitting layer composition 1 of Example 1, the content of the light-emitting layer composition was changed to the following light-emitting layer composition, and after the preparation, heated at 85 ° C. in a sealed state and allowed to stand for 10 minutes, exceeding 20 kHz The light emitting layer composition 2 was prepared in the same manner except that the sound wave was irradiated for 5 minutes and then 1 MHz ultrasonic wave was irradiated for 5 minutes.

(Light emitting layer composition)
Inorganic particles (organosilica: NBac-ST, manufactured by Nissan Chemical Co., Ltd.) 19.8 parts by weight Ir-A 5.0 parts by weight Ir-1 0.1 parts by weight Ir-14 0.1 parts by weight Isopropyl acetate 2,000 parts by weight << Preparation of Luminescent Layer Composition 3 >>
Organosol Quartron PL-2-TOL (Colloidal silica average particle size: 30 nm, colloidal silica content: 40% by mass, manufactured by Fuso Chemical Industry Co., Ltd.) 10 g, a solution obtained by dissolving 1 g of the above Ir complex (B) in 40 g of toluene. Was added to prepare a toluene dispersion having a colloidal silica content of 8% by mass.

<< Preparation of organic-inorganic composite light-emitting layer composition F >>
In the preparation of the organic-inorganic composite light-emitting layer composition A of Example 1, the organic-inorganic composite light-emitting layer composition was changed in the same manner except that the light-emitting layer composition was changed to the following and heated and dissolved at 85 ° C. under sealing after preparation. Product F was prepared.

(Composition of organic-inorganic composite light-emitting layer composition F)
Host-25 21.75 parts by mass Inorganic particle organosilica sol [NBAc-ST]
(According to Table 2) (As active ingredient) 0.75 parts by mass D-28 (according to Table 2) 2.4 parts by mass Ir-1 (according to Table 2) 0.05 parts by mass Ir-14 (according to Table 2) 0 .05 parts by mass Isopropyl acetate 2,000 parts by mass << Preparation of organic-inorganic composite light-emitting layer composition G >>
In the preparation of the organic-inorganic composite light-emitting layer composition F, the organic-inorganic composite light-emitting layer composition G was prepared in the same manner except that the light-emitting layer composition was changed to the following and heated and dissolved at 85 ° C. under sealing after preparation. Prepared.

(Composition of organic-inorganic composite light-emitting layer composition G)
Host-25 (according to Table 2) 21.75 parts by mass Blue-1 (according to Table 2) 0.72 parts by mass Green-1 (according to Table 2) 0.015 parts by mass Red-1 (according to Table 2) 0.015 Part by mass D-28 (according to Table 2) 2.4 part by mass Ir-1 (according to Table 2) 0.05 part by mass Ir-14 (according to Table 2) 0.05 part by mass Isopropyl acetate 2,000 parts by mass << Organic Preparation of inorganic composite light-emitting layer compositions H to O >>
In the preparation of the organic / inorganic composite light-emitting layer composition G, each of the organic / inorganic composite light-emitting layer compositions H to O was prepared in the same manner except that the addition amounts of inorganic particles, dopant, and host were changed as shown in Table 3. did.

<< Preparation of organic-inorganic composite light-emitting layer compositions P and Q >>
In preparing the organic / inorganic composite light-emitting layer composition G, the organic / inorganic composite light-emitting layer compositions P and Q were prepared in the same manner except that the host compound was changed to the polymer host compounds Host-53 and 54 shown in Table 3, respectively. did.

  About each of the obtained light emitting layer composition 2, 3 and organic-inorganic composite light emitting layer composition FQ, the constituent material of a light emitting layer, the presence or absence of organic-inorganic composite functional particles (inorganic particles and organic phosphorescent light emitting materials are shared) Ζ potential of the inorganic particles (indicating the ζ potential in the state of the inorganic particles alone or in the state where the inorganic particles and the organic phosphorescent light-emitting material are bound by covalent bonds), produced using each composition The refractive index of the light-emitting layer (the refractive index of the light-emitting layer produced using the composition is the same as the refractive index of the light-emitting layer produced by the composition alone or the light-emitting layer incorporated in the organic EL element) It was confirmed that the values were the same), and the scratch rank of the light emitting layer alone was evaluated.

  The refractive index and scratch rank were evaluated in the same manner as in Example 1. Moreover, the light emitting layer composition 1 quotes in Example 2 what was prepared in Example 1. FIG.

  The obtained results are shown in Table 3.

  Subsequently, using the light emitting layer compositions 1 to 3 and the organic / inorganic composite light emitting layer compositions F to Q, organic EL elements 2-1 to 2-15 were respectively produced as follows.

<< Production of Organic EL Elements 2-1 to 2-15 >>
An organic EL element 2-1 (comparative example) was produced in the same manner as in the production of the organic EL element 1 of Example 1. Next, in the production of the organic EL element 2-1 (comparative example), instead of the light emitting layer composition 1, the light emitting layer compositions 2 and 3 and the organic / inorganic composite light emitting layer compositions F to Q described in Table 3 were respectively used. Organic EL elements 2-2 and 2-3 (both are comparative examples) and 2-4 to 2-15 (both are the present invention) were produced in the same manner except that they were used.

(Evaluation of organic EL elements 2-1 to 2-15)
Each of the obtained organic EL elements 2-1 to 2-15 was evaluated for lifetime (light emission lifetime (%)), efficiency (external extraction quantum efficiency (%)), and voltage (driving voltage). The evaluation was performed in the same manner as described in Example 1.

  The life (%) and efficiency (%) are shown in Table 4 as relative evaluation with the evaluation data of the organic EL element 2-1 (comparative example) as 100 (%).

  From Table 4, compared with the comparative organic EL elements 2-1 to 2-3, the organic EL elements 2-4 to 2-15 of the present invention are superior in all the characteristics of life, efficiency, and voltage. Is clear.

Example 3
<< Preparation of organic-inorganic composite light-emitting layer composition R >>
In the preparation of the organic-inorganic composite light-emitting layer G of Example 2, the composition of the light-emitting layer composition was changed to the following, and the organic-inorganic composite light-emitting layer composition was similarly prepared except that it was heated and dissolved at 85 ° C. under sealing after preparation. R was prepared.

(Composition of organic-inorganic composite light-emitting layer composition)
HA (according to Table 5) 21.75 parts by mass Blue-1 (according to Table 5) 3.12 parts by mass Green-1 (according to Table 5) 0.065 parts by mass Red-1 (according to Table 5) 0.065 Mass parts Isopropyl acetate 2,000 parts by mass << Preparation of organic-inorganic composite light-emitting layer compositions S and T >>
In the preparation of the organic / inorganic composite light-emitting layer composition R, the organic / inorganic composite light-emitting layer composition was similarly prepared except that the addition amounts of inorganic particles, organic / inorganic composite functional particles, dopant and Host were changed as shown in Table 5. S and T were prepared respectively.

  For each of the obtained organic-inorganic composite light-emitting layer compositions R, S, and T, the constituent material of the light-emitting layer, the presence or absence of organic-inorganic composite functional particles (inorganic particles and organic phosphorescent light-emitting material are bonded by a covalent bond) ), Ζ potential of inorganic particles (indicating ζ potential in the state of inorganic particles alone or in the state where inorganic particles and organic phosphorescent light emitting material are bonded by covalent bond), refractive index of light emitting layer prepared using each composition (In addition, the refractive index of the light emitting layer produced using the composition is the same as that of the light emitting layer produced solely by the composition or the light emitting layer incorporated in the organic EL element. The scratch rank of the light emitting layer alone was evaluated.

  The refractive index and scratch rank were evaluated in the same manner as in Example 1.

  The results obtained are shown in Table 5.

  In Table 5, the light-emitting layer composition 1 and the organic / inorganic composite light-emitting layer compositions F and K are those prepared in Example 2.

  Subsequently, using the light emitting layer composition 1 and the organic / inorganic composite light emitting layer compositions F, K, R to T, the organic EL elements 2-1, 2-4, 2-9, 3-1 to 3− are as follows. 3 were prepared.

<< Preparation of organic EL elements 2-1, 2-4, 2-9, 3-1 to 3-3 >>
Similarly to the production of the organic EL element 1 of Example 1, the organic EL element 2-1 (comparative example) and the organic EL elements 2-4 and 2-9 of Example 2 are produced. 2-4 and 2-9 were prepared.

  Next, in the production of the organic EL element 2-9 (invention), the organic EL element was similarly prepared except that each of the light emitting layer compositions R, S and T shown in Table 5 was used instead of the light emitting layer composition K. Elements 3-1, 3-2 and 3-2 (all of the present invention) were produced.

(Evaluation of organic EL elements 2-1, 2-4, 2-9, 3-1 to 3-3)
About each of obtained organic EL element 2-1, 2-4, 2-9, 3-1 to 2-3, lifetime (light emission lifetime (%)), efficiency (external extraction quantum efficiency (%)), voltage Each (drive voltage) was evaluated. The evaluation was performed in the same manner as described in Example 1.

  The life (%) and efficiency (%) are shown in Table 6 as relative evaluation with the evaluation data of the organic EL element 2-1 (comparative example) as 100 (%).

  From Table 6, compared with the comparative organic EL element 2-1, the organic EL elements 2-4, 2-9, and 3-1 to 3-3 of the present invention are excellent in all the characteristics of life, efficiency, and voltage. It is clear that

  Furthermore, compared with the organic EL element 2-4 of the present invention in which the inorganic particles and the organic phosphorescent material are not covalently bonded, the inorganic particles and the organic phosphorescent material are covalently bonded. The organic EL elements 2-9 and 3-1 to 3-3 of the present invention are further excellent in the characteristics of the elements, and are particularly preferred embodiments. Are used, and the organic EL elements 3-1 to 3-3, which are a mode in which a free organic phosphorescent light emitting material is not contained, are further characterized by element characteristics (long life and high efficiency, In addition, it is understood that the low drive voltage is excellent.

  In addition, although the illustration which changed the dopant seed | species and the Host seed | species is not shown in this-application specification and an Example, the same effect is confirmed and the effect of this application is not limited to a specific compound. .

Claims (8)

In an organic electroluminescence device having an anode and a cathode on a substrate, a light emitting layer between the anode and the cathode, and at least one of the light emitting layers being an organic-inorganic composite light emitting layer,
The organic-inorganic composite light-emitting layer contains an organic phosphorescent light-emitting material, an organic carrier medium, and inorganic particles.   The organic electroluminescence device according to claim 1, wherein the organic carrier medium has a molecular weight of 10,000 or less.   The organic electroluminescence device according to claim 1, wherein the organic carrier medium is a host material.   The organic electroluminescent element according to any one of claims 1 to 3, wherein an isoelectric point of the inorganic particles is less than pH 4 or more than pH 9.8. The inorganic particles are WO ₃ , Sb ₂ O ₅ , V ₂ O ₅ , SiO ₂ , SiC, Ta ₂ O ₅ , La ₂ O ₃ , NiO, PbO, MgO, BeO, CdO, Cd (OH) ₂ , Co An inorganic particle having a composition of any one of (OH) ₂ , Fe (OH) ₂ , Mg (OH) ₂ , Mn (OH) ₂ , Ni (OH) _2, or V ₃ O _8. Item 5. The organic electroluminescence device according to Item 4.   Content of the inorganic particle in the said organic inorganic composite light emitting layer is 0.1 mass%-50 mass%, The organic electroluminescent element of any one of Claims 1-5 characterized by the above-mentioned.   The organic-inorganic composite functional particle in which the inorganic particle and the organic phosphorescent material are bonded, and the organic-inorganic composite functional particle is dispersed in an organic carrier medium. The organic electroluminescent element of any one of Claims.   The absolute value of ζ (zeta) potential of the organic-inorganic composite functional particle is 10 mV or more, and the organic-inorganic composite functional particle is covalently bonded to the organic phosphorescent material. Item 8. The organic electroluminescence device according to Item 7.