JPH06203963A - Organic electroluminescent device - Google Patents

Abstract

(57) [Abstract] [Purpose] Development of an organic EL device that has a color conversion function, excellent luminous efficiency, and is easy to manufacture. An organic electroluminescence device having a color-converting hole injecting and transporting region for color-converting light generated in a light emitting layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device, and more particularly to an organic electroluminescence device having a hole injecting / transporting region for color conversion of light generated in a light emitting layer.

[0002]

2. Description of the Related Art A method of converting an emission color of an organic electroluminescence element (hereinafter, sometimes abbreviated as an organic EL element) into another color or a method of mixing different colors. Conventionally, there are a doping method (JP-A-63-264692) and a fluorescence conversion method (US Pat. No. 5,126,214). The above doping method is
This is a method in which a small amount (5% by weight or less) of fluorescent molecules are mixed in the light emitting layer in order to enable color conversion, and luminescence can be extracted from the fluorescent molecules. However, in this doping method, when the fluorescent molecules are mixed in the light emitting layer, it is necessary to completely control the mixed amount to form a uniform film on the substrate. Since the hue and the efficiency are uneven, it is difficult to manufacture the organic EL device. In this method, the applied voltage to the organic EL element is often increased by about 1 to 2 V by mixing the dopant, and improvement has been demanded. Further, in the fluorescence conversion method, it is necessary to provide a color conversion film outside the organic EL element, which makes the manufacturing of the element complicated. By the way, WO91 /
No. 03142 discloses a device in which a conjugated oligomer is used as an organic semiconductor in a device structure of anode / organic semiconductor layer / organic insulator layer / cathode. It has been shown that a thiophene oligomer is used as an organic semiconductor in this device, and light emission with high brightness and high light emission efficiency is obtained from the light emitting layer in the organic insulator layer. This organic semiconductor is
In some cases, the energy gap is smaller than that of the light emitting material, and it is possible to provide an organic EL element having excellent light emitting efficiency. This is similar to the present invention, but does not disclose any color conversion using a hole injection layer with high fluorescence yield. Thus, the conventional device structure is basically anode / hole injection / transport layer (HTL) / electron transport region / cathode. Here, the electron injecting and transporting region is the light emitting layer, or the light emitting layer and the electron injecting layer. Specifically, the conventional element structure is as follows. (1) Anode / HTL / light emitting layer (EML) / cathode (2) Anode / HTL / EML / electron injection layer (ETL)
/ Cathode For the above device, a single hole injection layer, a multi-layer hole injection layer, or a layer in which a plurality of hole injection materials are mixed is used.
It is known to be used as a TL. On the other hand, an element structure of (3) anode / EML / ETL / cathode, in which HTL is used as a hole transporting light emitting layer, is also known. In the known device configurations (1) to (3), there is a recombination region in the EML where electrons and holes are recombined to generate an excited state. Therefore,
Light (hue) specific to the light emitting material forming the light emitting layer is generated. Further, in the above HTL, the hole mobility is sufficiently satisfied in the known hole injection region or the organic semiconductor, and the energy gap is also known in the known triarylamine-based, hydrazone-based or stilbene-based positive hole mobility. When using a hole injection material, one having a larger energy gap than that of the light emitting layer has been used. This allows electrons to be confined in the light emitting layer, and has a property that excitons generated in the light emitting layer are not transmitted to the hole injection layer side.

[0003]

Therefore, the present inventors have conducted intensive studies to solve the above-mentioned drawbacks of the prior art and develop a new color conversion method for an organic EL device. as a result,
It has been found that the above object can be achieved by using a hole injecting and transporting region that converts the energy generated by the recombination of electrons and holes generated in the light emitting layer to color-convert the light generated in the light emitting layer. The present invention has been completed based on such findings.

That is, the present invention provides an organic electroluminescent device having a color-converting hole injecting and transporting region for color-converting light generated in the light emitting layer.

The organic EL device of the present invention is characterized by having a color-converting hole injecting / transporting region for color-converting the light generated in the light emitting layer. The color-converting hole injecting and transporting region preferably has the following properties. The hole mobility in the color conversion hole injecting and transporting region is 10 ^−6.
cm ² / (V · sec) or more, preferably 10 ⁻⁵ cm ² / (V
・ Second) or more. The energy gap (excitation energy) of the color-converting hole injecting and transporting region is smaller than the energy gap of the light emitting layer. Preferably, the energy gap difference is 0.1
~ 1 eV. By using the color-converting hole injecting and transporting region in the organic EL device, it has a remarkably high fluorescence yield. The fluorescence yield is preferably 3% or more, more preferably 5% or more.

As a material used for such a color-converting hole injecting and transporting region, a stilbene-based material having the above-mentioned properties and an absorption wavelength of 440 nm or less is preferable, and a stilbene derivative or a distyrylarylene derivative is particularly preferable. Can be mentioned. Examples of the stilbene derivative include those represented by the general formula (I) or (II)

[0007]

[Chemical 1]

(In the formula, Ar ¹ represents an aryl group having 6 to 20 carbon atoms. R ^{1 to} R ⁴ each independently represent a hydrogen atom or an aryl group having 6 to 20 carbon atoms. D ^{1 to} D ³ represent 6 to 20 carbon atoms each independently substituted with an electron donating group
The aryl group of is shown. Here, Ar ¹ and R ^{1 to} R ⁴ may each independently be unsubstituted, or may be an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 1 carbon atoms.
It may be substituted with an aryloxy group having 0, an arylalkyl group having 6 to 10 carbon atoms, or an amino group having 1 to 20 carbon atoms. ) Is included. Further, as the distyrylarylene derivative, general formulas (III) and (I
V) or (V)

[0009]

[Chemical 2]

(In the formula, Ar ² and Ar ³ each independently represent an arylene group having 6 to 20 carbon atoms, Ar ⁴ represents an aryl group having 6 to 20 carbon atoms, and D ^{4 to} D ⁶ are the same as above. R ^{5 to} R ¹² each independently represent a hydrogen atom, wherein Ar ^{2 to} Ar ⁴ and R ^{5 to} R ¹² may each independently be unsubstituted or may be an alkyl group having 1 to 10 carbon atoms,
It may be substituted with an alkoxy group having 1 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylalkyl group having 6 to 10 carbon atoms, or an amino group having 1 to 20 carbon atoms. )

[0011]

[Chemical 3]

(Wherein Ar ⁵ , Ar ⁶ , Ar ⁸ and A
r < ⁹ > shows a C6-C20 aryl group each independently, Ar < ⁷ > shows a C6-C20 arylene group. R
¹³ and R ¹⁴ are each independently a hydrogen atom or a carbon number of 6
~ 20 aryl groups are shown. Here, Ar ^{5 to} Ar ⁹ may each independently be unsubstituted or may be an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 6 to 6 carbon atoms.
It may be substituted with an aryloxy group having 10 or an arylalkyl group having 6 to 10 carbon atoms. ) Is included.

The aryl group in the above general formulas (I) to (V) is preferably a phenyl group, a biphenylyl group, a naphthyl group, a pyrenyl group, a terphenylyl group, an anthranyl group, a tolyl group or a xylyl group. . Preferable examples of the arylene group include a phenylene group, a biphenylene group, a naphthylene group, an anthranylene group, a terphenylene group and a pyrenylene group. Further, the aryloxy group as the above substituent is a phenyloxy group,
Examples include biphenyloxy group, naphthyloxy group, anthranyloxy group, terphenyloxy group, pyrenyloxy group, etc., and alkyl groups include methyl group, ethyl group, isopropyl group, tertiary butyl group, pentyl group, hexyl group, etc. To be Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, and a pentyloxy group. Examples of the amino group include a dimethylamino group, a diethylamino group,
Examples thereof include diphenylamino group, phenylethylamino group, phenylmethylamino group, ditolylamino group, ethylphenylamino group, phenylnaphthylamino group and phenylbiphenylamino group. The general formula (I)-
D ^{1 to} D ⁶ in (V) are aryl groups having 1 to 20 carbon atoms and substituted with an electron donating group. Here, the electron donating group is preferably an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms, and particularly preferably 1 to 6 carbon atoms. 20 amino groups can be mentioned. This amino group has the general formula (VI)

[0014]

[Chemical 4]

(In the formula, X ¹ and X ² each independently represent an aryl group having 6 to 20 carbon atoms, an alkyl group having 1 to 10 carbon atoms or an arylalkyl group having 6 to 20 carbon atoms, which are bonded to each other. A saturated or unsaturated cyclic structure may be formed, and X ¹ and X ^{2 each} have an alkyl group having 1 to 10 carbon atoms, an arylalkyl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms. Alternatively, it may be substituted with an alkoxy group having 6 to 10 carbon atoms.
An aryl group substituted by an amino group represented by and X ¹ and X ²
It may be a nitrogen-containing aromatic ring group in which is bonded. ) Is included. Examples of the electron-donating group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and pentyl group, phenyloxy group, biphenyloxy group, naphthyloxy group, anthranyloxy group, terphenylyloxy group, methoxy group. Groups, ethoxy groups, isopropoxy groups, tert-butyloxy groups, pentyloxy groups and other alkoxy groups, dimethylamino groups, diethylamino groups, diphenylamino groups, phenylmethylamino groups, phenylethylamino groups, phenylmethylethylamino groups, Examples thereof include amino groups such as ditolylamino group, ethylphenylamino group, phenylnaphthylamino group and phenylbiphenylylamino group. Also, D
^As specific examples of ^{1 to} D ⁶ ,

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

Specific examples of the compounds represented by the general formulas (I) to (V) include the following compounds.

[0020]

[Chemical 8]

[0021]

[Chemical 9]

[0022]

[Chemical 10]

[0023]

[Chemical 11]

[0024]

[Chemical 12]

And the like.

Such a color converting hole injecting and transporting material is
As described above, it is preferable to have an energy gap smaller than that of the light emitting layer. By satisfying this condition, color conversion in the organic EL element is efficiently performed. Furthermore, in order to improve the color conversion efficiency, it is effective to use a color conversion material having a high fluorescence quantum yield in the solid state.

Next, the color conversion action in the hole injecting and transporting region, which is a feature of the present invention, will be described with reference to FIG. FIG. 1 shows the absorption spectrum (broken line) and the emission spectrum (thick line) of the light emitting layer and the absorption spectrum (thin line) of the color-converting hole injecting and transporting layer. Here, Eg1 in FIG. 1 indicates the upper limit wavelength of the absorption spectrum of the light emitting layer, and Eg2 indicates the upper limit wavelength of the absorption spectrum of the color-converting hole injecting and transporting layer. Here, Eg1 and Eg2 have a relationship of Eg1 <Eg2. As can be seen from FIG. 1, the absorption spectrum of the color-converting hole injecting and transporting layer and the emission spectrum of the light emitting layer are as follows.
Overlaps occur. The energy of this overlapping portion is absorbed by the hole injecting and transporting layer, whereby another emission spectrum that is color-converted by the emission of the hole injecting and transporting layer is generated. That is, the color conversion effect obtained in the present invention is such that the energy of light emission resulting from recombination of electrons and holes in the light emitting layer is
It is caused by absorption by the hole injecting and transporting material and new emission of light from the hole injecting and transporting layer. The light emission degree at this time is larger as the overlapping portion of the spectra is larger.

Further, the color conversion operation will be described by taking partial color conversion and complete color conversion as examples. (1) Partial color conversion FIG. 2 shows a spectrum that has been subjected to partial color conversion. Here, E is an emission spectrum by the light emitting layer, and C is an emission spectrum generated by color conversion. According to the spectrum shown in FIG. 2, it can be seen that color mixture is obtained because emission bands of E and C are generated. For example, when a blue light emission band is used for E, the color development after C is green when C is green, and the color development after C is white when C is red. (2) Complete color conversion FIG. 3 shows a spectrum subjected to perfect color conversion. E and C
Is the same as above. According to the spectrum shown in FIG. 3, it is understood that a complete color conversion is performed because only the C emission band is generated. According to this complete color conversion, various color conversions can be performed by using the hole injecting / transporting material that develops a color according to the purpose.

The color-converting hole injecting and transporting region used in the organic EL device of the present invention does not have to be layered, but is preferably used in the form of a layer or a layer. The following constitutions can be mentioned as preferable constitutions of the organic EL device of the present invention. Anode / color conversion hole injection transport region (CHTR) / E
ML / Cathode Anode / HTL / CHTR / HTL / EML / Cathode Anode / CHTR / HTL / EML / Cathode Anode / HTL / CHTR / EML / Cathode Anode / HTL / CHTR / EBL / EML / Cathode Anode / CHTR / EML / ETL / Cathode Here, HTL shows a well-known color non-converting hole injection layer.

As the above-mentioned EML, (a) an injection function (when a voltage is applied, holes can be injected from an anode or a hole injection layer, and electrons can be injected from a cathode or an electron injection layer) as in the case of a normal EML. , (B) transporting function (holes and electrons can be moved by the force of an electric field) and (c) light emitting function (providing a field for recombination of holes and electrons, It is possible to emit light.). The thickness of this layer is not particularly limited and can be appropriately determined depending on the situation, but is preferably 1 n.
m to 10 μm, particularly preferably 5 nm to 5 μm.
Here, as a preferable EML light emitting material (host material), a compound represented by the general formula (A) is used.

[0031]

[Chemical 13]

(Wherein Y ^{1 to} Y ⁴ are hydrogen atoms,
Alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, aralkyl group having 7 to 8 carbon atoms, substituted or unsubstituted aryl group having 6 to 18 carbon atoms, substituted or unsubstituted cyclohexyl group, substituted Or unsubstituted 6 to 1 carbon atoms
8 shows an aryloxy group and an alkoxy group having 1 to 6 carbon atoms. Here, the substituent is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 8 carbon atoms, an aryloxy group having 6 to 18 carbon atoms, and 1 to 6 carbon atoms.
, An acyloxy group having 1 to 6 carbon atoms, a carboxyl group, a styryl group, an arylcarbonyl group having 6 to 20 carbon atoms, an aryloxycarbonyl group having 6 to 20 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, Indicates a vinyl group, anilinocarbonyl group, carbamoyl group, phenyl group, nitro group, hydroxyl group or halogen. These substituents may be single or plural. In addition, Y ^{1 to} Y ⁴ may be the same or different from each other, and Y ¹ and Y ²
And Y ³ and Y ⁴ are bonded to the groups which are mutually substituted,
A substituted or unsubstituted saturated 5-membered ring or a substituted or unsubstituted saturated 6-membered ring may be formed. Ar represents a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, which may be mono-substituted or plural-substituted, and the binding site may be ortho, para, or meta. However,
When Ar is unsubstituted phenylene, Y ^{1 to} Y ⁴ are each an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 8 carbon atoms, a substituted or unsubstituted naphthyl group, a biphenyl group, a cyclohexyl group, an aryloxy group. More selected. ), General formula (B)

[0033]

[Chemical 14]

(In the formula, A and B each represent a monovalent group obtained by removing one hydrogen atom from the compound represented by the general formula (A), and may be the same or different. Q
Indicates a divalent group that cuts the conjugated system. ) Or general formula (C)

[0035]

[Chemical 15]

(In the formula, A¹Is a substituted or unsubstituted carbon
An arylene group of formula 6 to 20 or a divalent aromatic heterocyclic group
Indicates. The binding position can be ortho, meta, or para
Yes. A ²Is a substituted or unsubstituted ant having 6 to 20 carbon atoms
Group or a monovalent aromatic heterocyclic group. Y^FiveAnd Y
⁶Is a hydrogen atom, substituted or unsubstituted carbon number, respectively
6-20 aryl groups, cyclohexyl groups, monovalent aromas
Group heterocyclic group, C1-C10 alkyl group, C7
-20 aralkyl groups or C1-C10 alkoxy
Indicates a group. Note that Y^Five, Y⁶Can be the same or different
Yes. Here, the substituent is alkyl in the case of single substitution.
Having a group, an aryloxy group, an amino group or a substituent
It is a phenyl group that does not have a special feature. Y^FiveEach substituent of is A
¹Saturated or unsaturated five-membered or six-membered ring bound to
May be formed, and similarly Y⁶Each substituent of is A²Combined with
To form a saturated or unsaturated five-membered or six-membered ring
May be. In addition, Q represents a divalent group that cuts conjugation. )so
The compounds represented may be mentioned. The general formula (B) and
And Q in (C) represents a divalent group that cuts the conjugated system.
Here, the conjugation is due to the non-locality of π electrons and
Also due to heavy bonds or unpaired electrons or lone pairs
Including. Specifically for Q, from a straight-chain alkane to an H atom
A divalent group excluding one by one, for example,

[0037]

[Chemical 16]

It is represented. The reason for using a divalent group that cuts the conjugated system in this way is that A or B shown above is used.
(That is, the compound of the general formula (A)) is used alone as an organic EL device of the present invention, an EL emission color obtained;
This is because the EL emission color obtained when the compound represented by the general formula (B) is used as the organic EL device of the present invention does not change. That is, this is to prevent the light emitting layer represented by the general formula (A) or the general formula (B) from having a shorter wavelength or a longer wavelength. Also,
When connecting with a divalent group that cuts the conjugated system, the glass transition temperature (T
It can be confirmed that g) increases, and a uniform pinhole-free microcrystalline or amorphous thin film can be obtained, which improves the light emission uniformity. Furthermore, by binding with a divalent group that cuts the conjugated system, EL emission does not have a longer wavelength, and it has the advantage that synthesis or purification is easy. Further, as a preferable light emitting material (host material), 8-hydroxyquinoline,
Alternatively, a metal complex of a derivative thereof can be given. Specifically, oxines (generally 8-quinolinol or 8-
It is a metal chelate oxinoid compound containing a chelate of (hydroxyquinoline). Such compounds exhibit high levels of performance and are easily cast into thin film form. Examples of oxinoid compounds satisfy the following structural formula.

[0039]

[Chemical 17]

(In the formula, Mt represents a metal, n is an integer of 1 to 3, and Z is independent in each position, and in order to complete at least two or more condensed aromatic rings. Here, the necessary atoms are shown.) Here, the metal represented by Mt can be a monovalent, divalent or trivalent metal, and examples thereof include alkali metals such as lithium, sodium or potassium, magnesium or It is an alkaline earth metal such as calcium or an earth metal such as boron or aluminum. Any monovalent, divalent or trivalent metal generally known to be a useful chelating compound can be used.

Z represents an atom that forms a heterocycle in which one of at least two fused aromatic rings is azole or azine. Here, if necessary, another different ring can be added to the condensed aromatic ring. The number of atoms represented by Z is 18 in order to avoid adding a bulky molecule without any functional improvement.
It is preferable to keep below. Furthermore, specifically exemplifying the chelated oxinoid compound, tris (8-
Quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo-8-quinolinol)
Zinc, bis (2-methyl-8-quinolinate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8-quinolinol) Gallium, bis (5-chloro-8)
-Quinolinol) calcium, 5,7-dichloro-8-
Examples include quinolinol aluminum and tris (5,7-dibromo-8-hydroxyquinolinol) aluminum.

The EML can be formed by forming it into a thin film by a known method such as a vapor deposition method, a spin coating method, a casting method or an LB method, but a molecular volume film is particularly preferable. preferable. here,
The molecular volume film is a thin film formed by depositing the compound in a gas phase state, or a film formed by solidifying a molten state or a liquid phase state of the compound. Usually, this molecular volume film can be distinguished from a thin film (molecular cumulative film) formed by the LB method based on the difference in the agglomeration structure and the higher order structure, and the functional difference resulting therefrom. In addition, EML can be formed by dissolving it in a solvent together with a binder such as a resin to form a solution, and then thinning it by a spin coating method or the like. The film thickness of the EML thus formed is not particularly limited and can be appropriately selected depending on the situation, but is preferably 1 nm to 10 μm, particularly preferably 5 nm.
The range of nm to 5 μm is preferable. The general formulas (A) to (C)
Examples of the light emitting material represented by are the following compounds.

[0043]

[Chemical 18]

[0044]

[Chemical 19]

[0045]

[Chemical 20]

[0046]

[Chemical 21]

[0047]

[Chemical formula 22]

[0048]

[Chemical formula 23]

[0049]

[Chemical formula 24]

[0050]

[Chemical 25]

Further, the anode has a large work function.
(4 eV or more) metal, alloy, electrically conductive compound and this
Those using the mixture of these as electrode materials are preferably used.
It Specific examples of such an electrode material include Au and the like.
Metal, CuI, ITO, SnO ₂, ZnO, etc.
Examples include transparent materials. The anode uses these electrode materials
A thin film is formed by a method such as vapor deposition or sputtering.
It can be produced by Emitted from this electrode
When extracting light, make the transmittance greater than 10%
It is desirable that the sheet resistance as an electrode is several hundred.
Ω / □ or less is preferable. Furthermore, the film thickness depends on the material,
Usually, the range of 10 nm to 1 μm, especially 10 to 20 nm is preferable.
Good

On the other hand, as the cathode, a material having a low work function (4 eV or less), an alloy, an electrically conductive compound or a mixture thereof as an electrode substance is used. Specific examples of such electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium-silver alloys, Al / AlO ₂ , indium, rare earth metals and the like. The cathode can be prepared by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. Further, the sheet resistance as an electrode is preferably several hundreds Ω / □ or less, and the film thickness is usually 10 nm to 1 μm, particularly preferably 50 to 200 nm. In the device of the present invention, although not particularly specified, it is preferable that either the anode or the cathode is transparent or semi-transparent, because the emission is transmitted and the extraction efficiency is good.

Next, the HTL is not always necessary for this element, but it is preferable to use it for improving the light emission performance. As this HTL, a material that transports holes to EML at a lower electric field is preferable, and further, the mobility of holes is, for example, at least 10 ⁻⁶ cm ² / V when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied.・ Second is more preferable. Also, to keep the electrons in the EML, the EML
An electron barrier layer (EBL) can be used between the anode and the anode. There is no particular limitation on the material of such HTL as long as it has the above-mentioned preferable properties.
In the light-transmitting material, any material can be selected and used from materials commonly used as hole charge transport materials and known materials used in hole injection layers of EL devices.

Examples of the HTL material include triazole derivatives (see US Pat. No. 3,112,197, etc.),
Oxadiazole derivatives (see US Pat. No. 3,189,447, etc.), imidazole derivatives (JP-B-37-160)
96, etc.), polyarylalkane derivatives (US Pat. Nos. 3,615,402 and 3,820,989,
3,542,544, JP-B-45-555, JP-A-51-10983, JP-A-51-93224, JP-A-55-17105, JP-A-56-4148, and JP-A-55-108667. , Ibid. 55-15695
No. 3, JP-A-56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3,180,
729, 4,278,746, JP-A-55-8
No. 8064, No. 55-88065, No. 49-
No. 105537, No. 55-51086, No. 5
6-80051, 56-88141, 57-54545, 54-112637, 55-74546, etc.), phenylenediamine derivatives (US Pat. No. 3,615,404, patent) JP-A-51-10105, JP-A-46-3712, JP-A-47-25336, JP-A-54-53435, JP-A-54-1510536, and JP-A-54-11992.
No. 5, etc.), arylamine derivatives (US Patent No.
3,567,450, 3,180,703, 3,240,
No. 597, No. 3,658,520, No. 4,232,103, No. 4,175,961, No. 4,012,376, No. Sho 49-35702, No. 39-2757.
No. 7, JP-A-55-144250, No. 56-
119132, 56-22437, West German Patent 1,110,518, etc.), amino-substituted chalcone derivatives (US Pat. No. 3,526,501, etc.), oxazole derivatives (US Pat. No. 3,257,203, etc.) Those described), styrylanthracene derivatives (see JP-A-56-46234, etc.), fluorenone derivatives (see JP-A-54-110837, etc.), hydrazone derivatives (US Pat. No. 3,717,462, JP-A-SHO). 54
-59143, 55-52063, 5
No. 5-52064, No. 55-46760, No. 55-85495, No. 57-11350.
No. 57-148749, etc.), stilbene derivatives (Japanese Patent Laid-Open No. 61-210363, 61-228).
No. 451, No. 61-14642, No. 61-7.
No. 2255, No. 62-47646, No. 62-
36674, 62-10652, 62.
-30255, 60-93445, and 6
0-94462, 60-174749,
No. 60-175052, etc.) and the like. Furthermore, silazane derivatives (US Pat. No. 4,950,
950), polysilane type (Japanese Patent Laid-Open No. 20499/1990)
6), an aniline-based copolymer (JP-A-2-2822).
63).

In the present invention, as the material of HTL,
The following porphyrin compounds (JP-A-63-29569)
65, etc.) and aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,12.
7,412, JP-A-53-27033, 5
4-58445, 54-149634,
54-64299, 55-79450, 55-144250, 56-11913.
No. 2, gazette 61-295558 gazette, gazette 61-98.
353, 63-295695, etc.),
It is particularly preferable to use the aromatic tertiary amine compound.

As a typical example of the porphyrin compound,
Porphine, 1,10,15,20-tetraphenyl-
21H, 23H-porphine copper (II); 1,10,1
5,20-Tetraphenyl 21H, 23H-porphine cuprous (II); 5,10,15,20-Tetrakis (pentafluorophenyl) -21H, 23H-porphine;
Silicon phthalocyanine oxide; Aluminum phthalocyanine chloride; Phthalocyanine (no metal); Dilithium phthalocyanine; Copper tetramethylphthalocyanine;
Copper phthalocyanine; chromium phthalocyanine; zinc phthalocyanine; lead phthalocyanine; titanium phthalocyanine oxide; magnesium phthalocyanine; copper octamethylphthalocyanine and the like.

Typical examples of the aromatic tertiary amine compound and the styrylamine compound include N, N, N ',
N'-tetraphenyl-4,4'-diaminophenyl,
N, N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diaminobiphenyl, 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-tolylaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di) -P-tolylaminophenyl) phenylmethane, N, N'-diphenyl-
N, N'-di (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-
Examples include phenylcarbazole and aromatic dimethylidene compounds.

HTL can be formed by forming the above compound into a film by a known thin film method such as a vacuum vapor deposition method, a spin coating method and an LB method. The thickness of the hole injection layer is not particularly limited, but is usually 5 nm to 5 μm.
The hole injecting layer may be composed of one or more of the above hole injecting materials, or may be a single layer, or
The hole injection layer may be formed by stacking a hole injection layer made of a compound different from the hole injection layer.

On the other hand, as a material of EBL, for example,

[0060]

[Chemical formula 26]

[0061]

[Chemical 27]

[0062]

[Chemical 28]

[0063]

[Chemical 29]

[0064]

[Chemical 30]

There may be mentioned: Further, an adhesive layer (electron injection layer, adhesion improving layer) having excellent electron transfer properties and good adhesion to the cathode may be used between the EML and the cathode. The newly added adhesive layer preferably contains a material having high adhesion to the EML and the cathode. Examples of such a material having high adhesiveness include a metal complex of 8-hydroxyquinoline or a derivative thereof. Specific examples include metal chelate oxinoid compounds containing chelates of oxines (generally 8-quinolinol or 8-hydroxyquinoline). Further, a layer made of an oxadiazole derivative may be used instead of the adhesive layer. The oxadiazole derivative is represented by the general formula (IX) or (X)

[0066]

[Chemical 31]

(In the formula, Ar ^{8 to} Ar ¹⁰ and Ar ¹² each independently represent a substituted or unsubstituted aryl group;
r ¹¹ represents a substituted or unsubstituted arylene group. ) And an electron transfer compound represented by. Here, examples of the aryl group include a phenyl group, naphthyl group, biphenyl group, anthranyl group, perylenyl group, and pyrenyl group, and examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, an anthracenylene group, a perylenylene group, and a pyrenylene group. And so on. Examples of the substituent include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cyano group, and the like. The electron transfer compound is preferably one capable of forming a thin film. Specific examples of the electron transfer compound include:

[0068]

[Chemical 32]

And the like.

[0070]

The present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples. The invention is in no way limited by these examples. Example 1 A glass substrate (made by HOYA, NA40) having a size of 25 mm × 75 mm × 1 mm and ITO formed by a vapor deposition method to a thickness of 100 nm (made by HOYA) was used as a transparent support substrate. In addition, this substrate is 5 in isopropyl alcohol.
After ultrasonic cleaning for one minute, it was dried by blowing nitrogen and treated with UV and ozone dry stripper (UV300, manufactured by Samco International Co., Ltd.) for 10 minutes to remove contaminant impurities on the substrate surface. On this transparent support substrate, fixed to a substrate holder of a commercially available vapor deposition device (manufactured by Nippon Vacuum Technology Co., Ltd.), put 200 mg of copper phthalocyanine (CuPc) in a resistance heating boat made of molybdenum, and put it in another resistance heating boat made of molybdenum.

[0071]

[Chemical 33]

200 mg of (DPAVBi) was put into another resistance heating boat made of molybdenum and 4.4'-bis (2,2'-diphenylvinyl) biphenyl (DPVBi).
i)

[0073]

[Chemical 34]

200 mg of was added. Where CuPc
Is a hole injection material, DPAVBi is a color conversion hole transport material, and DPVBi is a light emitting material. Then, vacuum chamber 1
The pressure was reduced to × 10 ⁻⁴ Pa. After that, the boat containing CuPc was heated and vapor-deposited on the transparent support substrate at a vapor deposition rate of 0.1 to 0.3 nm / sec to form a hole injection layer having a film thickness of 20 nm. At this time, the temperature of the substrate was room temperature. Without removing this from the vacuum chamber, DPAV is added to the hole injection layer.
Bi is heated to a film thickness of 60 at a deposition rate of 0.1 to 0.5 nm / sec.
nm color-converting hole transport layer was formed. Then DPV
Bi is heated to a film thickness of 40 at a deposition rate of 0.1 to 0.4 nm / sec.
nm emission layer was formed. The obtained laminate on the substrate was taken out from the vacuum chamber, a mask made of stainless steel was installed, while 200 mg of Al complex (Alq) of 8-hydroxyquinoline was put into a resistance heating boat made of molybdenum, and resistance heating made of other molybdenum was made. Magnesium ribbon 1 on the boat
g, and 500 g of Ag was placed in another tungsten filament. Here, first, a resistance heating boat made of molybdenum containing Alq is heated to a vapor deposition rate of 0.1 to 0.3 nm.
An electron injection layer (adhesion improving layer) having a film thickness of 60 nm was formed at a speed of 10 sec / sec. Then, the magnesium ribbon and the Ag-containing molybdenum resistance heating boat are simultaneously heated to a vapor deposition rate of 1.7 n.
m / sec (magnesium ribbon), vapor deposition rate 0.07 to 0.0
A Mg: Ag alloy cathode was formed at 9 nm / sec (Al).
As a result of applying a voltage of 8 V to the obtained device, 5.6 mA /
A current of cm ² flowed, and green light emission with a light emission luminance of 130 cd / m ² was obtained. Furthermore, the measured emission spectrum is shown in FIG.
Shown in (solid line). From this spectrum, it was found that the TPD does not convert the excited state generated from DPVBi to emit blue light, whereas DPAVBi efficiently converts it to green emission. The emission spectrum of DPAVBi matches the fluorescence spectrum of DPAVBi.

Comparative Example 1 An organic EL device was produced in the same manner as in Example 1 except that the color-converting hole transporting material was changed from DPAVBi to TPD which was not a color-converting hole transporting material. As a result of applying a voltage of 8 V to the obtained device, a current of 6 mA / cm ² was flowed, and blue light emission with a light emission luminance of 100 cd / m ² was obtained. This is D
The emission color of PVBi is shown, and color conversion by TPD is not performed. The emission spectrum obtained was the same as the dotted line in FIG.

Example 2 Color Convertible Hole Transport Material from DPAVBi to Color Convertible Hole Transport Material

[0077]

[Chemical 35]

An organic EL device was produced in the same manner as in Example 1 except that DTVA was used instead. As a result of applying a voltage of 14 V to the obtained device, a current of 110 mA / cm ² was flown, and green light emission with a light emission luminance of 610 cd / m ² was obtained. As a result of measuring the emission spectrum, it was found that the emission was color-converted by DTVA.

Comparative Example 2 An organic EL device was produced in the same manner as in Example 2 except that the color conversion hole transport material was changed from DTVA to TPD which was not a color conversion hole transport material. A voltage of 9V is applied to the obtained device.
As a result, a current of 10 mA / cm ² was flown, and blue light emission with an emission luminance of 180 cd / m ² was obtained. This is DP
The emission color of VBi is shown, and color conversion by TPD is not performed. The emission spectrum obtained was the same as the broken line in FIG.

Reference Example 1 The energy gap of the hole transporting material having color conversion property was compared with the energy gap of the light emitting material. For comparison, the energy gap between CuPc and TPD, which has no color conversion property, is shown. Material name Energy gap (eV) 1 DPAVBi 2.7 2 DTVA 2.6 3 DPVBi (EML material) 3.0 4 CuPc 2.0 5 TPD 3.1 From the above comparison results, the following can be confirmed. The energy gap of the color-converting hole transport material is smaller than the energy gap of the light emitting layer. A non-fluorescent material such as CuPc having the above properties but no color conversion cannot be used as a color conversion hole transport material. In contrast, DPAVB
i and DTVA are so fluorescent that they can be clearly confirmed under normal room lighting with a normal UV lamp (mercury lamp). Further, when the energy gap is larger than that of the light emitting layer like TPD, it has no color conversion property. The energy gap value can be measured by various known methods, but this time, the method estimated from the absorption edge was adopted.

[0081]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the emission spectrum obtained in the light emitting layer can be color-converted in the hole injecting and transporting region, more uniform emission can be obtained, and the production efficiency is excellent. An easy organic EL element is provided. Therefore, the organic EL device of the present invention can be effectively used in information industrial equipment such as a display device, particularly in a display device.

[Brief description of drawings]

FIG. 1 shows an absorption spectrum of a light emitting layer of an organic EL device, an emission spectrum of the organic EL device, and an absorption spectrum of a hole injecting and transporting material.

FIG. 2 shows an emission spectrum showing partial color conversion.

FIG. 3 shows an emission spectrum showing complete color conversion.

FIG. 4 shows emission spectra obtained in Example 1 and Comparative Example 1.

[Explanation of symbols]

Eg1: Upper limit wavelength of absorption spectrum of light emitting layer Eg2: Upper limit wavelength of absorption spectrum of color-converting hole injecting and transporting material C: Emission spectrum generated by color conversion E: Emission spectrum of light emitting layer

Claims (6)

[Claims] 1. An organic electroluminescence device having a color-converting hole injecting and transporting region for color-converting light generated in a light emitting layer. 2. The mobility of holes in the color-converting hole injecting and transporting region is 10 ⁻⁶ cm ² / (V · sec) or more, the energy gap of the region is smaller than the energy gap of the light emitting layer, and The organic electroluminescence device according to claim 1, which has a high fluorescence quantum yield. 3. The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is laminated in the order of anode / color conversion hole injecting / transporting region / light emitting layer / cathode. 4. The organic electroluminescent device according to claim 1, wherein the anode / color-converting hole injecting / transporting region / light emitting layer / electron injecting layer / cathode are laminated in this order. 5. The organic electroluminescence according to claim 1, wherein the layers are laminated in the order of anode / color conversion hole injecting / transporting region / hole injecting / transporting layer / light emitting layer / electron injecting layer / cathode. element. 6. The organic electroluminescent device according to claim 1, wherein the anode / color-converting hole injecting / transporting region / hole injecting / transporting layer / light emitting layer / cathode are laminated in this order.