JP4794919B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to a light-emitting element that can emit light by converting electric energy into light, and particularly relates to an organic electroluminescent element (hereinafter also referred to as “light-emitting element” or “organic EL element” as appropriate).

An organic electroluminescence (EL) element has attracted attention as a promising display element because it can emit light with high luminance at a low voltage. As a means for improving luminous efficiency, a light-emitting element using a carbazole derivative as a host material has been reported (for example, refer to Patent Document 1), but further improvement is desired in terms of luminous efficiency and durability.
JP 2003-133075 A

  An object of the present invention is to provide an organic electroluminescence device having high luminous efficiency (low driving voltage, power consumption, etc.) and good driving durability.

The above object has been achieved by the following means.
In the organic electroluminescent device having at least one organic compound layer including a light emitting layer between <1> pair of electrodes, the light-emitting layer, and at least one phosphorescent material, represented by the SL one general formula (2) the organic electroluminescent device characterized by containing at least one kind of that compound.

In general formula (2), R ²⁰¹ and R ²¹¹ each represent a hydrogen atom, R ²⁰⁶ and R ²¹⁶ each independently represent an alkyl group or an aryl group, and R ²⁰⁴ and R ²¹⁴ each independently represent an alkyl group. Or an aryl group, R ²⁰⁵ and R ²¹⁵ each represent a hydrogen atom, and R ²²¹ , R ²²² , R ²²³ , R ²²⁴ , R ²²⁵ , R ²²⁶ , R ²²⁷ , and R ^{228 each} represent a hydrogen atom.

< 2 > The organic electroluminescent element according to < 1 >, wherein the light emitting layer further contains at least one kind of electron transporting material.
<3> The organic electroluminescent element as described in <1> or <2>, wherein the phosphorescent material is an iridium complex.

  According to the present invention, it is possible to provide an organic electroluminescent element having high luminous efficiency (low driving voltage, power consumption, etc.) and good driving durability.

Hereinafter, the present invention will be described in detail.
The organic EL device of the present invention is an organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, the light-emitting layer, and at least one phosphorescent material, the following general formula (1) characterized in that it contains at least one compound represented by a preferred embodiment the general formula of the compounds represented in (2).

In general formula (1), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , and R ¹¹⁶ are each independently hydrogen Represents an atom or a substituent, and at least two of R ¹⁰¹ , R ¹⁰⁶ , R ¹¹¹ , and R ¹¹⁶ represent a substituent. The substituents represented by R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , and R ¹¹⁶ are adjacent to each other. They may combine to form a ring structure.

In general formula (2), R ²⁰¹ and R ²¹¹ each represent a hydrogen atom, R ²⁰⁶ and R ²¹⁶ each independently represent an alkyl group or an aryl group, and R ²⁰⁴ and R ²¹⁴ each independently represent an alkyl group. Or an aryl group, R ²⁰⁵ and R ²¹⁵ each represent a hydrogen atom, and R ²²¹ , R ²²² , R ²²³ , R ²²⁴ , R ²²⁵ , R ²²⁶ , R ²²⁷ , and R ^{228 each} represent a hydrogen atom .

  Since the organic EL device of the present invention has the above-described configuration, it can be a device having high luminous efficiency and good driving durability.

Preferably Ri I as the organic EL device of the present invention, in the light emitting layer, at least one compound represented by the general formula (2), phosphorescent materials, and, in an organic EL element containing at least an electron transporting material is there.
In the following description, a compound represented by one general formula (2), sometimes collectively referred to as "the compounds of the present invention".

The compound represented by the general formula (1) will be described.
In general formula (1), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , and R ¹¹⁶ are each independently hydrogen Represents an atom or a substituent, and at least two of R ¹⁰¹ , R ¹⁰⁶ , R ¹¹¹ , and R ¹¹⁶ represent a substituent.
The substituents represented by R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , and R ¹¹⁶ are adjacent to each other. They may combine to form a ring structure. As the substituent forming the ring structure, R ¹⁰² and R ¹⁰³ , and R ¹¹² and R ¹¹³ are preferable. For example, R ¹⁰² and R ¹⁰³ may be bonded to form a benzo condensed ring to form a carbazole ring in the molecule.

Examples of the substituent represented by R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , and R ¹¹⁶ include an alkyl group ( Preferably it has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, Vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), alkynyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably carbon 2-10, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably 6-30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-12 carbon atoms). Yes, for example, phenyl, p-methylphenyl, naphthyl, anthranyl, etc.), amino group (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms). For example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, etc.), an alkoxy group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, especially Preferably it has 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy An aryloxy group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2 -Naphthyloxy, etc.), heterocyclic oxy groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyloxy, pyrazyloxy, Pyrimidyloxy, quinolyloxy, etc.),

An acyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl), an alkoxycarbonyl group. (Preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group (preferably 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include phenyloxycarbonyl and the like, acyloxy groups (preferably 2 to 30 carbon atoms, and more). Preferably it has 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy, benzo And acylamino groups (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino. ), An alkoxycarbonylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonyl An amino group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), a sulfonylamino group (preferably 1-30 carbon atoms, more preferably 1-20 carbon atoms, particularly preferably 1-12 carbon atoms. Yes, for example, methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl group (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 12 carbon atoms, , Sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 carbon atom). -12, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, and the like.

An alkylthio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), an arylthio group (preferably having a carbon number) 6 to 30, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, etc.), a heterocyclic thio group (preferably 1 to 30 carbon atoms, more preferably carbon The number is from 1 to 20, particularly preferably from 1 to 12, and examples thereof include pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio and the like, and a sulfonyl group (preferably). Has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc. ), Sulfinyl groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido A group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include ureido, methylureido, phenylureido), phosphoric acid amide group (Preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include diethyl phosphate amide and phenyl phosphate amide), a hydroxy group, Mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, Ruboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably having 1 to 12 carbon atoms). Atoms, oxygen atoms, sulfur atoms, specifically imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group and the like. A group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, such as trimethylsilyl, triphenylsilyl, etc.), a silyloxy group (preferably carbon 3 to 40, more preferably 3 to 30 carbon atoms, particularly preferably C3-C24, for example, trimethylsilyloxy, triphenylsilyloxy, etc. are mentioned. ) And the like.
These substituents may be further substituted.

As the substituent represented by R ¹⁰¹ and R ¹¹¹ , an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, and an amino group are preferable, an alkyl group and an aryl group are more preferable, an aryl group is further preferable, A phenyl group is particularly preferred.

R ¹⁰² , R ¹⁰³ , R ¹¹² , and R ¹¹³ are preferably a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, or a group that forms a ring structure by combining with an adjacent substituent. A group which is bonded to form a ring structure is more preferable, and a group which is bonded to an adjacent substituent to form an aromatic ring (nitrogen-containing heterocycle, aromatic hydrocarbon ring) is more preferable, and is bonded to an adjacent substituent. Particularly preferred is a group which forms an aromatic hydrocarbon ring.

The substituent represented by R ¹⁰⁴ and R ¹¹⁴ is preferably an alkyl group, an aryl group, or a heteroaryl group, more preferably an aryl group or a heteroaryl group, still more preferably an aryl group, and particularly preferably a phenyl group.

R ¹⁰⁵ and R ¹¹⁵ are preferably a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom or an amino group, more preferably a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, and a hydrogen atom An aryl group is more preferable, and a hydrogen atom is particularly preferable.

R ¹⁰⁶ and R ¹¹⁶ are preferably a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom or an amino group, more preferably a hydrogen atom, an alkyl group or an aryl group, and a hydrogen atom or an aryl group. More preferred is a hydrogen atom.

At least two of R ¹⁰¹ , R ¹⁰⁶ , R ¹¹¹ , and R ¹¹⁶ are substituents.

The compound represented by the general formula (1) is more preferably a compound represented by the general formula (2). In the compound represented by the general formula (2), R ¹⁰² and R ¹⁰³ and R ¹¹² and R ¹¹³ in the general formula (1) are bonded to form a benzo-fused ring, thereby forming two carbazole rings in the molecule. This is the embodiment.

The general formula (2) which is a compound according to the present invention will be described.
R ²⁰¹ and R ²¹¹ represent a hydrogen atom.
R ²⁰⁶ and R ²¹⁶ each independently represents an alkyl group or an aryl group, and the alkyl group or aryl group has the same meaning as the alkyl group or aryl group represented by R ¹⁰⁶ and R ¹¹⁶ in the general formula (1) ; The preferred range is also the same.
R ²⁰⁴ and R ²¹⁴ each independently represents an alkyl group or an aryl group, and the alkyl group or aryl group has the same meaning as the alkyl group or aryl group represented by R ¹⁰⁴ and R ¹¹⁴ in the general formula (1) , The preferred range is also the same.
R ²⁰⁵ and R ²¹⁵ represent a hydrogen atom.

^{R 221, R 222, R 223} , R 224, R 225, R 226, R 227, and R ²²⁸ represents a hydrogen atom.

  The compound according to the present invention may be a low molecular compound, and is an oligomer compound, a polymer compound having a structure represented by the general formula (1) or the general formula (2) in a main chain or a side chain (weight average) The molecular weight (in terms of polystyrene) may preferably be 1000 to 5000000, more preferably 2000 to 1000000, and still more preferably 3000 to 100,000. The compound according to the present invention is preferably a low molecular compound.

Next, although the compound example of the compound concerning this invention is shown, this invention is not limited to these.

The compound according to the present invention can be synthesized using various known methods.
For example, as shown in the following scheme, the compound listed above as the exemplary compound (1-1) is prepared by reducing a known nitro compound, adjusting the halide by diazotization and Sandmeyer reaction, and further with hydrazone. It can be synthesized through a coupling reaction, cyclization (JACS 121, 10251 (1999)), and oxidation.

  Other compounds than the exemplary compound (1-1) can be similarly synthesized from the corresponding nitro compound, amino compound, and halide.

The compound according to the present invention is contained in at least one layer of the organic compound layer, preferably contained in the light emitting layer, a layer existing between the anode and the light emitting layer, and more preferably contained in the light emitting layer. .
Compounds according to the present invention, embodiments are contained in the light emitting layer as both a host material and a light-emitting materials is phosphorescent material is particularly preferred.

The compound which concerns on this invention may be used individually by 1 type, and may use 2 or more types together.
As content in the organic compound layer 1 layer of the compound based on this invention, 30-100 mass% is preferable, 40-99 mass% is more preferable, 40-95 mass% is further more preferable.

  The light emitting material contained in the light emitting layer is preferably a phosphorescent material such as an iridium complex, platinum complex, rhenium complex, osmium complex, ruthenium complex, or a metal complex having a tridentate or higher ligand. It is more preferably a metal complex-based phosphorescent light-emitting material having a ligand of at least a locus, and further preferably a platinum complex-based phosphorescent material having a tetradentate ligand.

  Examples of the phosphorescent light emitting material include Japanese Patent Application No. 2004-088575, Japanese Patent Application No. 2004-162849, Japanese Patent Application No. 2005-069963, Japanese Patent Application No. 2004-270644, Japanese Patent Application No. 2005-04939, Japanese Patent Application No. 2004-279153, Japanese Patent Application No. 2005-075759, The compounds (phosphorescent materials, metal complexes (platinum complexes)) described in each specification such as Japanese Patent Application Nos. 2005-075341, 2005-07092, and 2005-0753340 are also preferably used.

  The light emitting materials as described above may be used alone or in combination of two or more in the light emitting layer. As content of the luminescent material in a light emitting layer, 1-50 mass% is preferable, 3-30 mass% is more preferable, 5-20 mass% is further more preferable.

In the present invention, in the light emitting layer, the compound according to the present invention, a phosphorescent material, which is contained, as these content ratio (mass ratio), the compound is a phosphorescent light emitting material according to the present invention More preferably, the compound according to the present invention is more preferably twice or more of the phosphorescent material, and the compound of the present invention is more preferably four times or more of the phosphorescent material.

In the present invention, from the viewpoint of luminous efficiency (power consumption) and durability, the light emitting layer contains at least a compound represented by the general formula (1), a phosphorescent light emitting material, and an electron transporting material. This is a more preferred embodiment.
The electron transporting material used in the light emitting layer is not particularly limited, but is preferably a nitrogen-containing heterocyclic compound, a metal complex, or a silicon-containing compound, more preferably a nitrogen-containing heterocyclic compound or a metal complex, and a nitrogen-containing heterocyclic compound. Further preferred.

  In the case where the light emitting layer contains an electron transporting material together with the compound according to the present invention and the phosphorescent light emitting material, the content of the electron transporting material is preferably 30 to 100% by mass, more preferably 40 to 99% by mass. 40 to 95% by mass is more preferable. The content ratio between the compound according to the present invention and the electron transporting material is preferably more than the electron transporting material from the viewpoint of durability, and the compound according to the present invention is preferably an electron transporting material. 1.5 times or more of the conductive material is more preferable, and the compound according to the present invention is more preferably twice or more of the electron transporting material.

The suitable aspect of the organic EL element (organic EL element of this invention ) which contains the compound which concerns on this invention in an organic compound layer (light emitting layer) is further demonstrated.

The external quantum efficiency of the organic EL device of the present invention is preferably 5% or more, more preferably 10% or more, and further preferably 13% or more. The value of the external quantum efficiency should be the maximum value of the external quantum efficiency when the device is driven at 20 ° C. or the value of the external quantum efficiency near 100 to 300 cd / m ² when the device is driven at 20 ° C. Can do.

The external quantum efficiency is calculated by “external quantum efficiency φ = number of photons emitted from the device / number of electrons injected into the device” (“external quantum efficiency φ = internal quantum efficiency × light extraction efficiency”). It can be said that a larger element is more advantageous in terms of power consumption.
In the present invention, using a source measure unit type 2400 manufactured by Toyo Technica, a constant DC voltage was applied to the organic EL element to emit light, and the luminance was measured using a luminance meter BM-8 manufactured by Topcon Corporation. On the other hand, the emission peak wavelength and the emission spectrum waveform are measured using a spectrum analyzer PMA-11 manufactured by Hamamatsu Photonics, and the external quantum efficiency at 100 cd / m ² can be calculated therefrom.
The external quantum efficiency in this specification is measured by this method.

  Specifically, the external quantum efficiency of the light-emitting element can be calculated from a result of measuring the luminance, emission spectrum, and current density and a specific luminous efficiency curve. That is, the number of input electrons can be calculated using the current density value. The emission luminance can be converted into the number of photons emitted by integral calculation using the emission spectrum and the relative visibility curve (spectrum). From these, the external quantum efficiency (%) can be calculated by “(number of emitted photons / number of electrons input to the device) × 100”.

  The internal quantum efficiency of the organic EL device of the present invention is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. The internal quantum efficiency of the device is calculated by internal quantum efficiency = external quantum efficiency / light extraction efficiency. In a normal organic EL element, the light extraction efficiency is about 20%. However, the shape of the substrate, the shape of the electrode, the thickness of the organic layer, the thickness of the inorganic layer, the refractive index of the organic layer, the refractive index of the inorganic layer, etc. By devising it, it is possible to increase the light extraction efficiency to 20% or more.

  The details of each layer constituting the organic electroluminescent element of the present invention are as described later, but an element having at least three layers of a hole transport layer, a light emitting layer, and an electron transport layer is preferable.

  The ionization potential of the host material contained in the light emitting layer is preferably 5.8 eV or more and 6.3 eV or less, and preferably 5.95 eV or more and 6.25 eV or less from the viewpoint of reducing the driving voltage of the device. More preferably, it is 6.0 eV or more and 6.2 eV or less.

The electron mobility of the host material contained in the light emitting layer is preferably 1 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻¹ cm ² / Vs or less from the viewpoint of reducing the driving voltage of the device. It is more preferably 5 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less, and 1 × 10 ⁻⁵ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less. Is more preferably 5 × 10 ⁻⁵ cm ² / Vs or more and cm ² / Vs or less.

The hole mobility of the host material contained in the light emitting layer is preferably 1 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻¹ cm ² / Vs or less from the viewpoint of reducing the driving voltage of the device. It is more preferably 5 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less, and 1 × 10 ⁻⁵ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less. Is more preferably 5 × 10 ⁻⁵ cm ² / Vs or more and 1 × 10 ⁻² cm 2 / Vs or less.

  From the viewpoint of improving the thermal stability of the device, the glass transition point of the host material contained in the light emitting layer in the present invention, the electron transport material contained in the electron transport layer, and the hole transport material contained in the hole transport layer is It is preferably 90 ° C or higher and 400 ° C or lower, more preferably 100 ° C or higher and 380 ° C or lower, further preferably 120 ° C or higher and 370 ° C or lower, and particularly preferably 140 ° C or higher and 360 ° C or lower. .

Moreover, when applying the organic EL element of this invention to blue light emission, it is preferable that it is the following aspects.
The maximum wavelength of light emission is preferably from 390 nm to 495 nm, more preferably from 400 nm to 490 nm, from the viewpoint of blue color purity. The organic EL device of the present invention may have a light emission maximum wavelength of 500 nm or more, or may be a white light emitting device.

  From the viewpoint of blue color purity, the x value of the CIE chromaticity value of light emission is preferably 0.22 or less, and more preferably 0.20 or less.

  From the viewpoint of blue color purity, the y value of the CIE chromaticity value of luminescence is preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.15 or less.

  The half width of the emission spectrum is preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less, and particularly preferably 70 nm or less from the viewpoint of blue color purity.

The T ₁ level (energy level of the lowest triplet excited state) of the phosphorescent material in the light emitting layer is 60 kcal / mol or more (251.4 kJ / mol or more), 90 kcal / mol from the viewpoint of improving the light emission efficiency of blue light emission. Or less (377.1 kJ / mol or less) is preferable, 62 kcal / mol or more (259.78 kJ / mol or more), 85 kcal / mol or less (356.15 kJ / mol or less) is more preferable, and 65 kcal / mol or more (272.35 kJ / mol). mol or more) and 80 kcal / mol or less (335.2 kJ / mol or less).

The T ₁ level (minimum triplet excited state energy level) of the host material in the light emitting layer is 60 kcal / mol or more (251.4 kJ / mol or more), 90 kcal / mol or less from the viewpoint of improving the emission efficiency of blue light emission. (377.1 kJ / mol or less) is preferable, 62 kcal / mol or more (259.78 kJ / mol or more), 85 kcal / mol or less (356.15 kJ / mol or less) is more preferable, and 65 kcal / mol or more (272.35 kJ / mol). More preferably, it is 80 kcal / mol or less (335.2 kJ / mol or less).

The layer adjacent to the light emitting layer (hole transport layer, electron transport layer, charge block layer, exciton block layer, etc.) has a T ₁ level (lowest triplet excited state energy level) of 60 kcal / mol or more (251.4 kJ / Mol or higher), 90 kcal / mol or lower (377.1 kJ / mol or lower) is preferable, 62 kcal / mol or higher (259.78 kJ / mol or higher), 85 Kcal / mol or lower (356.15 kJ / mol or lower) is more preferable, and 65 kcal. / Mol or more (272.35 kJ / mol or more) and 80 kcal / mol or less (335.2 kJ / mol or less).

The configuration of the organic EL element of the present invention will be described in more detail.
The organic EL device of the present invention is configured to have at least one organic compound layer including a light emitting layer between a pair of electrodes of an anode and a cathode, and the general formula (1) and the general formula are provided in at least one layer of the organic compound layer. It contains at least one compound represented by the formula (2) (compound according to the present invention).

The organic EL element of the present invention is not particularly limited such as a system, a driving method, and a usage form.
Moreover, the organic EL element of this invention can improve light extraction efficiency by various well-known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The organic EL device of the present invention is a so-called top emission method in which light emission is extracted from the cathode side (described in JP-A Nos. 2003-208109, 2003-248441, 2003-257651, 2003-282261, etc.) It may be.

  The substrate used in the organic EL device of the present invention is not particularly limited, but inorganic materials such as zirconia-stabilized yttrium and glass, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polycarbonate, and polyether. High molecular weight materials such as sulfone, polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), Teflon (registered trademark), polytetrafluoroethylene-polyethylene copolymer Also good.

  The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like, and a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Is a material having a work function of 4 eV or more. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver, chromium and nickel, and these metals and conductive metal oxides. Inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO, preferably conductive metals It is an oxide, and ITO is particularly preferable from the viewpoint of productivity, high conductivity, transparency, and the like. The thickness of the anode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, and further preferably 100 nm to 500 nm.

As the anode, a layer formed on a soda-lime glass, non-alkali glass, a transparent resin substrate or the like is usually used. When glass is used, it is preferable to use non-alkali glass as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. The thickness of the substrate is not particularly limited as long as it is sufficient to maintain the mechanical strength, but when glass is used, a thickness of 0.2 mm or more, preferably 0.7 mm or more is usually used.
Various methods are used for producing the anode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.), a coating of a dispersion of indium tin oxide, etc. A film is formed by this method.
The anode can be subjected to cleaning or other treatments to lower the drive voltage of the element or increase the light emission efficiency. For example, in the case of ITO, UV-ozone treatment, plasma treatment, etc. are effective.

  The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, and stability between the negative electrode and the adjacent layer such as the electron injection layer, the electron transport layer, and the light emitting layer. It is selected in consideration of etc. As a material for the cathode, a metal, an alloy, a metal halide, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include an alkali metal (for example, Li, Na, K, etc.) and its fluoride. Or oxides, alkaline earth metals (eg Mg, Ca, etc.) and fluorides or oxides thereof, gold, silver, lead, aluminum, sodium-potassium alloys or their mixed metals, lithium-aluminum alloys or their mixtures Examples thereof include metals, magnesium-silver alloys or mixed metals thereof, rare earth metals such as indium and ytterbium, preferably materials having a work function of 4 eV or less, more preferably aluminum, lithium-aluminum alloys or mixed metals thereof. , Magnesium-silver alloys or mixed metals thereof. The cathode can take not only a single layer structure of the compound and the mixture but also a laminated structure including the compound and the mixture. For example, a laminated structure of aluminum / lithium fluoride and aluminum / lithium oxide is preferable. The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, and further preferably 100 nm to 1 μm.

For production of the cathode, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a coating method, and a transfer method are used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.
The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

In the present invention, the organic compound layer may have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, and the like in addition to the light emitting layer. It may be provided with the function. Various materials can be used for forming each layer.
In the present invention, an embodiment having at least three layers of a hole transport layer, a light emitting layer, and an electron transport layer is preferable.
The method for forming the organic compound layer in the present invention is not particularly limited, but resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method (spray coating method, dip coating method, impregnation method, roll coating method) , Gravure coating method, reverse coating method, roll brush method, air knife coating method, curtain coating method, spin coating method, flow coating method, bar coating method, micro gravure coating method, air doctor coating, blade coating method, squeeze coating method Transfer roll coat method, kiss coat method, cast coat method, extrusion coat method, wire bar coat method, screen coat method, etc.), ink jet method, printing method, transfer method, etc. are used. Resistance heating vapor deposition, coating method, transfer It is preferred.

The light-emitting layer in the invention, you containing at least one phosphorescent material and at least one compound according to the present invention. Compounds according to the present invention contained in the light emission layer, phosphorescent material, and the details of the electron transporting material are as described above.

  The material contained in the light emitting layer can inject holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, and can inject electrons from the cathode, the electron injection layer, or the electron transport layer. Any layer can be used as long as it can form a layer having a function, a function of moving injected charges, and a function of emitting light by providing a recombination field of holes and electrons.

  As a material contained in the light emitting layer, in addition to materials such as the compound according to the present invention described in detail above, for example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, Metals of naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, 8-quinolinol Various metal complexes represented by complexes and rare earth complexes, polymer compounds such as polythiophene, polyphenylene, polyphenylene vinylene, organic silane, iridium trisphenylpyridine complex, and Transition metal complexes typified by gold porphyrin complexes, and derivatives thereof.

  Although the film thickness of a light emitting layer is not specifically limited, Usually, the thing of the range of 1 nm-5 micrometers is preferable, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.

  The formation method of the light emitting layer is not particularly limited, but among the above-described organic compound layer formation methods, resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method, ink jet method, printing method, LB And a transfer method are used, and resistance heating vapor deposition and coating methods are preferable.

Also, the light emitting layer may be one more even (single layer) (stacked structure), and each layer may emit light in different luminescent colors may be emitted as a whole such as white , White light may be emitted from a single light emitting layer. When there are a plurality of light emitting layers, each light emitting layer may be formed of a single material or a plurality of compounds.

  When the light emitting layer has a laminated structure, the number of laminated layers is preferably 2 or more and 50 or less, more preferably 4 or more and 30 or less, and still more preferably 6 or more and 20 or less.

  When the light emitting layer has a laminated structure, the thickness of each layer constituting the laminated structure is not particularly limited, but is preferably 0.2 nm to 20 nm, more preferably 0.4 nm to 15 nm, and more preferably 0.5 nm to 10 nm. More preferably, 1 nm to 5 nm is particularly preferable.

The light emitting layer may have a plurality of domain structures. The light emitting layer may have another domain structure. For example, the light emitting layer, and a region of approximately 1 nm ³ of a mixture of a host material A and phosphorescent material B, may be constituted in the region of about 1 nm ³ of a mixture of a host material C and phosphorescent material D. The diameter of each domain is preferably from 0.2 nm to 10 nm, more preferably from 0.3 nm to 5 nm, still more preferably from 0.5 nm to 3 nm, and particularly preferably from 0.7 nm to 2 nm.

  The light emitting layer may further contain a blue fluorescent light emitting compound. Moreover, you may produce a multicolor light emission device and a full color light emission device using the blue light emitting element containing a blue fluorescent compound, and the organic EL element of this invention simultaneously.

  The material of the hole injection layer and the hole transport layer may be any one having a function of injecting holes from the anode, a function of transporting holes, or a function of blocking electrons injected from the cathode. Good. Specific examples include carbazole, triazole, oxazole, oxadiazole, imidazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic group Tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic Examples include silane, carbon films, compounds of the present invention, and derivatives thereof.

  The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and further preferably 10 nm to 500 nm. is there.

  The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

  As a method for forming the hole injection layer and the hole transport layer, among the methods for forming the organic compound layer described above, a vacuum deposition method, an LB method, or a method of coating by dissolving or dispersing the hole injection transport material in a solvent Ink jet method, printing method, and transfer method are used. In the case of the coating method, it can be dissolved or dispersed together with the resin component. Examples of the resin component include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, and poly (N -Vinyl carbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, and the like.

  The material contained in the electron injection layer and the electron transport layer may be any material having any one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes injected from the anode. . Specific examples include fragrances such as triazole, oxazole, oxadiazole, imidazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyrandioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, naphthalene, and perylene. Various metal complexes represented by metal complexes of cyclic tetracarboxylic anhydride, phthalocyanine, 8-quinolinol, metal phthalocyanine, benzoxazole and benzothiazole as ligands, organic silanes, and derivatives thereof Can be mentioned.

The film thicknesses of the electron injection layer and the electron transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and further preferably 10 nm to 500 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  As a method for forming the electron injection layer and the electron transport layer, among the above-described organic compound layer formation methods, a vacuum deposition method, an LB method, a method in which the electron injection transport material is dissolved or dispersed in a solvent, and a coating method, an ink jet method , Printing method, transfer method and the like are used. In the case of the coating method, it can be dissolved or dispersed together with the resin component. As the resin component, for example, those exemplified in the case of the hole injection transport layer can be applied.

The organic EL device of the present invention may have a protective layer in order to prevent moisture and oxygen from entering.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device. Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ , and CaF ₂ , SiN _x , SiO _x N _y Such as nitride, polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene And a copolymer obtained by copolymerizing a monomer mixture containing at least one comonomer, a fluorine-containing copolymer having a cyclic structure in the copolymer main chain, a water-absorbing substance having a water absorption of 1% or more, a water absorption of 0 .1% or less of moisture-proof substances and the like.
There is also no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation) (Ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

  Furthermore, in this invention, you may seal the whole element of this invention using a sealing container. Moreover, you may enclose a water | moisture-content absorber or an inert liquid in the space between a sealing container and an element. The moisture absorbent is not particularly limited, but for example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride, Examples thereof include cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. .

  The use of the light emitting device of the present invention is not particularly limited, but is suitable for the fields of display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source, sign, signboard, interior, optical communication, etc. Can be used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Comparative Example 1]
The cleaned ITO substrate was put in a vapor deposition apparatus, and copper phthalocyanine was vapor-deposited to 5 nm, and NPD (N, N′-di-α-naphthyl-N, N′-diphenyl) -benzidine) was vapor-deposited thereon to 40 nm. On top of this, Ir (ppy) ₃ and CBP were vapor-deposited at a ratio of 6:94 (mass ratio) at 30 nm, and BAlq was vapor-deposited thereon at 6 nm, on which Alq (tris (8-hydroxyquinoline) was deposited. Aluminum complex) was deposited by 20 nm. On top of this, 3 nm of lithium fluoride was vapor-deposited, and then 60 nm of aluminum was vapor-deposited, whereby the light emitting device of Comparative Example 1 was produced.

As a result of applying a DC constant voltage to the light emitting element to emit light using a source measure unit type 2400 manufactured by Toyo Technica, green light emission derived from Ir (ppy) ₃ was obtained.

The structures of NPD, CBP, Ir (ppy) ₃ , BAlq, and Alq used above are shown below.

[Comparative Example 2]
A light emitting device of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the following Compound A was used instead of CBP used in Comparative Example 1.

As a result of applying a DC constant voltage to the EL element to emit light using a source measure unit type 2400 manufactured by Toyo Technica, green light emission derived from Ir (ppy) ₃ was obtained.
When the driving durability of this light emitting device was evaluated by the luminance half-life of the device driven at 1 mA (light emitting area 4 mm ² ), it was equivalent to the light emitting device of Comparative Example 1.
In addition, the drive voltage of the element necessary for flowing a current of 1 mA (light emitting area 4 mm ² ) was lower than that of the light emitting element of Comparative Example 1 by about 1V.

[Example 1]
A light emitting device of Example 1 was fabricated in the same manner as Comparative Example 1 except that the exemplified compound (1-1) described above was used instead of CBP used in Comparative Example 1.
Using a source measure unit 2400 type manufactured by Toyo Technica, a direct-current constant voltage was applied to the light emitting element obtained above to emit light, and as a result, green light emission derived from Ir (ppy) ₃ was obtained.
When the driving durability of this light emitting device was evaluated by the luminance half-life of the device driven at 1 mA (light emitting area 4 mm ² ), it was twice that of the light emitting device of Comparative Example 1.
In addition, the driving voltage of the element required for flowing a current of 1 mA (light emitting area 4 mm ² ) was lower by about 2 V than the light emitting element of Comparative Example 1.

[Example 2]
A light emitting device of Example 2 was produced in the same manner as Comparative Example 1 except that the exemplified compound (1-14) described above was used instead of CBP used in Comparative Example 1.
As a result of emitting light by applying a DC constant voltage to the light-emitting element obtained above using a source measure unit type 2400 manufactured by Toyo Technica, blue-green light emission was obtained.
When the driving durability of this light emitting device was evaluated by the luminance half life of the device driven at 1 mA (light emitting area 4 mm ² ), it was 1.5 times that of the device of Comparative Example 1.
In addition, the drive voltage of the element necessary for flowing a current of 1 mA (light emitting area 4 mm ² ) was lower than that of the light emitting element of Comparative Example 1 by about 1V.

[Example 3]
A light emitting device of Example 3 was fabricated in the same manner as Comparative Example 1 except that the exemplified compound (1-1) and the following compound B were used in a ratio of 3: 1 instead of CBP used in Comparative Example 1. did.

Using a source measure unit 2400 type manufactured by Toyo Technica, a direct-current constant voltage was applied to the light emitting element obtained above to emit light, and as a result, green light emission derived from Ir (ppy) ₃ was obtained.
When the driving durability of this light emitting device was evaluated by the luminance half life of the device driven at 1 mA (light emitting area 4 mm ² ), it was 2.5 times that of the light emitting device of Comparative Example 1.
In addition, the driving voltage of the element required for flowing a current of 1 mA (light emitting area 4 mm ² ) was lower by about 2.5 V than the light emitting element of Comparative Example 1.

  As shown in the above examples, the organic EL elements of Examples 1 to 3 containing the compound according to the present invention in the organic compound layer (the light emitting layer in this example) are elements having excellent driving durability. It was confirmed. Moreover, it turned out that the organic EL element of Example 3 in which the light emitting layer contains the compound according to the present invention, the phosphorescent light emitting material, and the electron transporting material exhibits particularly excellent effects.

  In addition to the compounds according to the present invention used in the above-described examples, organic EL elements with high driving durability can also be produced for elements using other compounds according to the present invention.

Claims (3)

In the organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, the light-emitting layer, and at least one phosphorescent material, a compound represented by the following Symbol one general formula (2) the organic electroluminescent device characterized by containing at least one kind.

In general formula (2), R ²⁰¹ and R ²¹¹ each represent a hydrogen atom, R ²⁰⁶ and R ²¹⁶ each independently represent an alkyl group or an aryl group, and R ²⁰⁴ and R ²¹⁴ each independently represent an alkyl group. Or an aryl group, R ²⁰⁵ and R ²¹⁵ each represent a hydrogen atom, and R ²²¹ , R ²²² , R ²²³ , R ²²⁴ , R ²²⁵ , R ²²⁶ , R ²²⁷ , and R ^{228 each} represent a hydrogen atom. The organic light emitting device according to claim 1 , wherein the light emitting layer further contains at least one kind of electron transporting material.   The organic electroluminescent element according to claim 1, wherein the phosphorescent material is an iridium complex.