JP2000080362A - Organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an element exhibiting a large luminance and excellent in color purity, a luminescence lifetime and the like by forming, between electrodes, at least one organic thin film layer containing naphthoquinoneimine- based compound forming a light-emitting layer. SOLUTION: This electroluminescence element is equipped with an anode and a cathode, and has at least one organic thin film layer including a light- emitting layer between a pair of electrodes, at least one of thin film layers containing a naphthoquinoneimine-based compound represented by formula I or II. As the naphthoquinoneimine-based compounds there can be exemplified 4-[4-(dimethylamino)phenylimino]-2-ethylcarbamoyl-1,4-naphthoquinone and the like, and 4,8-bis(4-ethylphenylamino)-1,5-naphthoquinone and the like, and these naphthoquinoneimine compounds are admixed in an amount of 0.001-50 wt.% based on a light-emitting host material. As the host material is employed a quinoline-based metal complex or the like such as tris(8-quinolinol)aluminum or the like. In the formulae, R1-R4 each represents hydrogen, halogen, alkyl, alkoxy, aryl or the like.

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 (hereinafter, sometimes simply referred to as "organic EL device") used for a flat light source or a display device.
More specifically, the present invention relates to a red light emitting organic EL device.

[0002]

2. Description of the Related Art Organic EL elements are expected to be used as self-luminous flat display elements. Organic EL elements are different from inorganic EL elements in that they are not restricted by AC drive and require high voltage, and are considered to be easy to be multi-colored due to the variety of organic compounds. It is expected to be applied and is being actively developed.

When the organic EL device is applied to a full-color display, three primary colors of red, green and blue are used.
It is necessary to obtain color light emission. Many examples of green light emission have been reported. For example, a device using Tris (8-quinolinol) aluminum (Applied Physics Letters (Applied P
hyisics Letters), 51, 913
1987) and devices using a diarylamine derivative (JP-A-8-53397).

As for the blue light emitting device, a device using a stilbene compound (Japanese Patent Application Laid-Open No. 5-295359) and a device using a triarylamine derivative (Japanese Patent Application Laid-Open No. 7-539) are also available.
No. 55), an element using a tetraaryldiamine derivative (JP-A-8-48656), an element using a styrylated biphenyl compound (JP-A-6-132080), and the like.
There are numerous reports. In addition, there have been reports of devices using a distyrylarylene conductor as a light-emitting material and achieving a luminance of 20,000 cd / m ² or more, a luminous efficiency of 51 m / W, and a half-life of 5,000 hours or more. (Special lecture of the 70th Annual Meeting of the Chemical Society of Japan).

Japanese Patent Application Laid-Open No. Hei 3-15297 discloses an organic EL device which can emit red light by converting the wavelength of blue light emitted from a fluorescent dye layer into a fluorescent dye layer. In JP-A-288184 and JP-A-8-286033, red light emission is obtained by doping a red fluorescent dye into a light-emitting layer capable of emitting green or blue light. Is not enough, and further improvement is required for practical use.

[0006]

However, in the above-mentioned method using a color conversion filter, a sufficient luminous efficiency cannot be obtained because the quantum yield for color conversion of EL light emission by the filter is limited. However, there is a problem that the cost due to the use of the filter cannot be avoided.

Further, the red light-emitting material exemplified above as a conventional example has a low quantum yield of fluorescence, and can emit light only at a luminance of about 1000 cd / m ² even when the current flowing inside the element is increased, and is practical. Was lacking.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a red light-emitting organic EL device having high light emission luminance, excellent color purity, and excellent light emission life.

[0009]

The present invention provides the following (A) to (I) organic EL devices to achieve the above object.

(A) In an organic electroluminescence device having a cathode and an anode and having at least one organic thin film layer including a light emitting layer between the pair of electrodes, at least one of the organic thin film layers has the following structural formula ( An organic electroluminescent device comprising the naphthoquinone imine compound represented by the above 1).

Embedded image (In the formula, R _{1 to} R ₄ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an aryl group, or a hydroxyl group.)

(B) The naphthoquinone imine compound represented by the structural formula (1) is 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone or 4- (4-dimethyl) (Amino-2-methylphenylimino) -2-ethylcarbamoyl-1,4-
The organic electroluminescent device according to (A), which is naphthoquinone.

(C) In an organic electroluminescence device having a cathode and an anode and having at least one organic thin film layer including a light emitting layer between the pair of electrodes, at least one of the organic thin film layers has the following structural formula ( An organic electroluminescent device comprising the naphthoquinone imine compound represented by the above 2).

Embedded image (Wherein, R _{1 and} R ₂ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an aryl group, or a hydroxyl group.)

(D) The naphthoquinone imine compound represented by the structural formula (2) is 4,8-bis (4-ethylphenylamino) -1,5-naphthoquinone or 4,8-bis (4-methoxyphenylamino) ) The organic electroluminescent device of (C), which is -1,5-naphthoquinone.

(E) The organic electroluminescent device of (A) to (D), wherein the light emitting layer is a layer containing a naphthoquinone imine compound represented by the structural formula (1) or (2). .

(F) The light emitting layer has a thickness of 500 nm to 580 nm.
(A) to (A), comprising a green and yellow light-emitting material having an EL spectrum and a naphthoquinone imine compound represented by the structural formula (1) or (2).
(D) The organic electroluminescence element.

(G) A naphthoquinone imine compound represented by the structural formula (1) or (2) is contained in a range of 0.001 wt% to 50 wt% with respect to the green and yellow light emitting materials. F) The organic electroluminescence device.

(H) The light-emitting layer comprises: a quinoline-based metal complex;
The organic electroluminescent device according to any one of (A) to (D), which is a layer containing the naphthoquinone imine compound represented by the structural formula (1) or (2).

(I) The light emitting layer is a layer containing a bisstyrylanthracene derivative and a naphthoquinone imine compound represented by the structural formula (1) or (2). D) The organic electroluminescent element.

The red light-emitting material used in the present invention, that is, the naphthoquinone imine compound represented by the structural formula (1) or (2) has an absorption in the green region and has a wavelength of 600 to 700.
Since the compound exhibits fluorescence with a high quantum yield in the red region of nm, red light required for colorization of the organic EL device can be obtained with high luminance and high efficiency by using the above-described light emitting material. Further, since the red light-emitting material used in the present invention has a high quantum yield, light emission can be obtained in a red region with high luminance by mixing a small amount into the light-emitting layer of the organic EL element. It does not hinder the movement of carriers injected into the substrate. In addition, the red light-emitting material is
A thin film can be easily formed by a resistance heating type film forming method, the thin film state is extremely stable and excellent in flatness, and no change in the film structure such as crystallization or formation of an aggregated state is observed. The organic EL device of the invention can easily achieve a long life. From the above, the organic E according to the present invention
L element is a red light emitting element of a color display device,
It is valid.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the organic EL device of the present invention. This organic EL device has a hole transport layer 5 between an anode 2 and a cathode 3 provided on a glass substrate 1.
, A light emitting layer 6 and an electron transport layer 7 in this order.

The structure of the organic EL device of the present invention is not limited. For example, the structure shown in FIGS. The organic EL device shown in FIG. 2 is provided with a hole injection layer 4, a hole transport layer 5, a light emitting layer 6, and an electron transport layer 7 between an anode 2 and a cathode 3. Organic E in FIG.
The L element has a structure in which a hole transport layer 5 and a light emitting layer 6 are sequentially provided between an anode 2 and a cathode 3. The organic EL device of FIG. 4 has a light emitting layer 6 and an electron transport layer 7 between an anode 2 and a cathode 3.
Are sequentially provided.

The organic EL device of the present invention comprises at least one organic thin film layer between the cathode and the anode, in particular, a light-emitting layer.
The naphthoquinone imine compound represented by the structural formula (1) or (2) is contained.

Here, examples of R _{1 to} R ₄ in the naphthoquinone imine compound represented by the structural formula (1) are shown below, but the compound of the structural formula (1) is not limited to the following examples. _{· R 1 = R 2 = R} 3 = R 4 = CH 3 · R 1 = R 2 = R 3 = CH 3 R 4 = C 2 H 5 · R 1 = R 2 = R 3 = CH 3 R 4 = C _{3 H 7 · R 1 = R} 2 = R 3 = CH 3 R 4 = H · R 1 = R 2 = CH 3 R 3 = H R 4 = C 2 H 5 · R 1 = R 2 = C 2 H 5 R ₃ = R ₄ = CH ₃ · R ₁ = R ₂ = C ₂ H ₅ R ₃ = R ₄ = H · R ₁ = R ₂ = CH ₃ R ₃ = OCH ₃ R ₄ = CH ₃ · R ₁ = R _{2 = C 6 H 5 R 3} = H R 4 = CH 3

Examples of R _{1 to} R ₂ in the naphthoquinone imine compound represented by the structural formula (2) are shown below, but the compound of the structural formula (2) is not limited to the following examples. _{· R 1 = R 2 = CH} 3 · R 1 = R 2 = C 2 H 5 · R 1 = R 2 = C 3 H 7 · R 1 = R 2 = H · R 1 = R 2 = OCH 3 · R _{1 = R 2 = Cl · R} 1 = R 2 = OH

Among the above exemplified compounds, 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone represented by the following structural formula (1-1): )), 4- (4-dimethylamino-2-methylphenylimino) -2-ethylcarbamoyl-1,4-naphthoquinone, 4,8-bis (4-ethylphenylamino)-of the following structural formula (2-1) 1,5-
Naphthoquinone and 4,8-bis (4-methoxyphenylamino) -1,5-naphthoquinone of the following structural formula (2-2) are particularly preferable in consideration of luminance, luminous efficiency, luminance half-life, and chromaticity coordinates.

[0026]

Embedded image

Embedded image

Embedded image

Embedded image

Examples of the host material (green and yellow light-emitting materials) of the light-emitting layer include quinoline-based metal complexes such as 8-hydroxyquinoline metal complex represented by tris (8-quinolinol) aluminum of the following structural formula (a). Examples include bisstyrylanthracene derivatives of structural formula (b), distyrylbenzene derivatives such as 1,4-bis (2-methylstyryl) benzene, coumarin derivatives, oxadiazole derivatives, and perinone derivatives. As a combination with the compound, tris (8-
A quinoline-based metal complex such as an 8-hydroxyquinoline metal complex represented by quinolinol) aluminum, and a bisstyrylanthracene derivative are preferable because high luminance and luminous efficiency can be obtained.

[0028]

Embedded image

Embedded image

The light emitting layer may contain the naphthoquinone imine compound as a mixture with other hole transporting materials, electron transporting materials and light emitting materials.

The naphthoquinone imine compound is present in an amount of 0.001 wt% to 50 wt% based on the host material of the light emitting layer.
It is appropriate to mix in the range of. If the amount of the naphthoquinone imine-based compound is less than 0.001 wt%, there is a problem that the chromaticity is deteriorated.
Luminous efficiency decreases, which is not preferable. The thickness of the light emitting layer is preferably in the range of 10 to 100 nm.

The hole injecting material forming the hole injecting layer of the organic EL device according to the present invention is not particularly limited, and a metal or metal-free phthalocyanine represented by the following structural formula (c) (X is hydrogen, M- Y is selected from Cu, VO, TiO, Mg, and H ₂ ), and a star burst type molecule such as 4,4 ′, 4 ″ -tris (diphenylamino) triphenylamine of the following structural formula (d) is used. It is possible.

[0032]

Embedded image

Embedded image

The hole transporting material for forming the hole transporting layer of the organic EL device of the present invention is not particularly limited, and any compound can be used as long as it is a compound usually used as a hole transporting material. is there. For example, as the hole transporting material, bis (di (p-tolyl) aminophenyl-1,1-cyclohexane represented by the following structural formula (e), N, N ′ represented by the following structural formula (f) Diphenyl-N, N-bis (3-methylphenyl) -1,1′-biphenyl-
4,4′-diamine, N, represented by the following structural formula (g)
N'-diphenyl-NN-bis (1-naphthyl)-
(1,1′-biphenyl) -4,4′-diamine, a star burst type molecule represented by the structural formula (d), and the like.

[0034]

Embedded image

Embedded image

Embedded image

The electron transporting material for forming the electron transporting layer of the organic EL device of the present invention is not particularly limited, and any compound that is commonly used as an electron transporting material can be used. For example, as the electron transporting material, 2- (4-biphenyl) -5- (4-t-butylphenyl) -1,3,4- represented by the following structural formula (h)
Oxadiazole, oxadiazole derivatives such as bis {2- (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene represented by the following structural formula (i), and triazole derivatives Oxine metal complex, pyrazine derivative, pyridine derivative, perylene derivative, perillin derivative, bisstyryl derivative and the like.

[0036]

Embedded image

Embedded image

As the material for the anode, a transparent material having a large work function and can be suitably used. For example, a conductive metal oxide such as indium tin oxide (ITO), tin oxide or indium oxide may be used. Materials, gold, platinum, chromium, and the like. As a material of the cathode, a metal having a small work function or an alloy of the metal and an alkali metal, an alkaline earth metal can be suitably used.Examples thereof include aluminum, silver, tin, and lithium, magnesium,
Alloys with potassium and sodium.

[0038]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 FIG. 1 shows a sectional structure of an organic EL device according to Example 1. The organic EL device according to this embodiment includes a transparent support substrate (glass substrate) 1, an anode 2 and a cathode 3 formed on the glass substrate 1, and an organic thin film layer sandwiched between the anode 2 and the cathode 3. 5 to 7.

The procedure for fabricating the organic EL device according to Example 1 will be described below. First, an anode 2 was formed on a glass substrate by sputtering so as to have a sheet resistance of 15 Ω / □ or less. The glass with ITO was subjected to ultrasonic cleaning with pure water and isopropyl alcohol, respectively, and then dried over boiling isopropyl alcohol. Further, the substrate was cleaned with a UV ozone cleaning device and attached to a substrate holder of a vacuum evaporation device.

Further, N, N′-diphenyl-N, N′-bis (α-naphthyl) -1,1′-biphenyl-4,4′-diamine (α) was used as a hole transport layer 5 on a board made of molybdenum. -NPD), 200 mg of tris (8-quinolinol) aluminum (Alq3) as the host of the light emitting layer 6 and the electron transport layer 7, and 4- [4- (dimethylamino) phenylimino] -2- as the guest of the light emitting layer.
100 m of ethylcarbamoyl-1,4-naphthoquinone
g, which was attached to a current-carrying terminal, and the inside of the vacuum layer was evacuated to 2 × 10 ⁻⁴ Pa. Then, electricity is supplied to a board containing N, N'-diphenyl-N, N'-bis (α-naphthyl) -1,1'-biphenyl-4,4'-diamine, and a deposition rate of 0.3 nm / sec. Was evaporated to a thickness of 50 nm.

Next, a board containing tris (8-quinolinol) aluminum and 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone was added to a board containing 0.3 nm / sec. An electric current is supplied using another deposition power supply so that the latter has a deposition rate of 0.02 to 0.03 nm / sec. When the deposition rates of both materials are stabilized, the shutter is opened and the thickness of the mixed film is reduced. At 30 nm, 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-
The deposition power of 1,4-naphthoquinone was turned off, and then only tris (8-quinolinol) aluminum was deposited to a thickness of 30 nm.

Next, support substrate / ITO / α-NPD / tris (8-quinolinol) aluminum: 4- [4-
(Dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone / tris (8-quinolinol) aluminum was fitted with a stainless steel shadow mask. Here, 3 g of aluminum was put in a BN boat, and attached to a terminal for energization. Similarly, 500 mg of Li was put into a tungsten filament and attached to another current-carrying terminal. After evacuating the vacuum layer to 1 × 10 ⁻⁴ Pa, the deposition rate of aluminum was 0.2 nm /
The current was supplied using another deposition power supply such that the deposition rate of lithium was 0.02 to 0.03 nm / sec. When the deposition rates of both materials are stabilized, the shutter is opened and the thickness of the mixed film is reduced to 30 n.
m, the lithium vapor deposition power supply was stopped, and an aluminum film was formed until the film pressure reached 170 nm.
Was formed.

The vacuum layer is returned to atmospheric pressure, and the supporting substrate / ITO
/ Α-NPD / tris (8-quinolinol) aluminum: 4- [4- (dimethylamino) phenylimino]-
2-ethylcarbamoyl-1,4-naphthoquinone / tris (8-quinolinol) aluminum / AlLi / Al
An organic EL device was produced. In this device, ITO was used as a positive electrode, an aluminum electrode was used as a negative electrode, the current when 10 V was applied was 8 mA / cm ² , and the maximum luminance was 4800 cd / m ² (2
0 V). The chromaticity coordinates at 400 cd / m ² were red light emission of (X: 0.629, Y: 0.331), and the light emission efficiency at this time was 0.80 [lm / W].

Further, the above-mentioned device was placed in nitrogen and the initial luminance was 200
As a result of a driving test performed at cd / m ² , the luminance half time was 5
It was 300 hours. Further, the above-described device is
After storage for 00 hours, a non-light-emitting portion called a dark spot was observed. As a result, there was no change from that immediately after the film formation, and no growth was observed.

Example 2 After a glass substrate with ITO prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, N, N'-diphenyl-N, N '-Di (3-methylphenyl) -1,1'
-Biphenyl-4,4'-diamine (TPD)
mg, 200 mg of tris (8-quinolinol) aluminum as a host and an electron transport layer, and 4-mg as a guest.
(4-dimethylamino-2-methylphenylimino)-
2-ethylcarbamoyl-1,4-naphthoquinone in 10
After putting 0 mg into the terminal and attaching it to a current-carrying terminal, the inside of the vacuum layer was evacuated to 2 × 10 ⁻⁴ Pa. Then, a current was applied to the board containing the hole injecting and transporting layer, and vapor deposition was performed at a vapor deposition rate of 0.3 nm / sec until the film thickness reached 50 nm.

Next, a current was supplied to the board containing tris (8-quinolinol) aluminum and 4- (4-dimethylamino-2-methylphenylimino) -2-ethylcarbamoyl-1,4-naphthoquinone. 0.3 nm /
The latter was co-deposited at a deposition rate of 0.02 to 0.03 nm / sec until the thickness became 30 nm. Subsequently, only tris (8-quinolinol) aluminum was deposited to a thickness of 30 nm.

Next, support substrate / ITO / TPD / tris (8-quinolinol) aluminum: 4- (4-dimethylamino-2-methylphenylimino) -2-ethylcarbamoyl-1,4-naphthoquinone / tris (8 -Quinolinol) A stainless steel shadow mask was mounted on top of the aluminum. Here, 3 g of aluminum was put in a BN boat, and attached to a terminal for energization. Similarly, 500 mg of Li is put into a tungsten filament,
Attached to another energizing terminal. The vacuum layer is 1 × 10 ^-4 Pa
After evacuation, the deposition rate of aluminum is 0.2 nm
/ Sec, and at the same time, using another deposition power source so that the deposition rate of lithium is 0.02 to 0.03 nm / sec. When the deposition rates of both materials have stabilized, the shutter is opened and the thickness of the mixed film is reduced to 30.
When the thickness reached nm, the power supply for lithium deposition was stopped, and an aluminum film was formed to a thickness of 170 nm.

The vacuum layer is returned to the atmospheric pressure again, and the supporting substrate /
ITO / TPD / Tris (8-quinolinol) aluminum
Um: 4- (4-dimethylamino-2-methylphenyl)
Imino) -2-ethylcarbamoyl-1,4-naphthoki
Non / Tris (8-quinolinol) aluminum / Al
An organic EL device made of Li / Al was produced. This element
10V with ITO as positive electrode and aluminum electrode as negative electrode
As a result, the current is 7 mA / cm^TwoFlow, maximum brightness
4500 cd / m^Two(20V), 400 cd / m ^TwoTime color
Red light emission at degree coordinates (X: 0.640, Y: 0.316)
I got The luminous efficiency at this time is 0.76 [lm / W].
Was.

Further, the above-mentioned element was placed in nitrogen at an initial luminance of 200.
As a result of a driving test performed at cd / m ² , the luminance half time was 5
500 hours. Further, the above-described device is
After storage for 00 hours, a non-light-emitting portion called a dark spot was observed. As a result, there was no change from that immediately after the film formation, and no growth was observed.

Example 3 An ITO glass substrate prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, five crucibles made of high-purity graphite were prepared, and copper phthalocyanine was used separately as a hole injection layer. And N, N′-diphenyl-N, N′-bis (α-naphthyl) as a hole transport layer
-1,1'-biphenyl-4,4'-diamine (α-NP
D), 1 g of tris (8-quinolinol) aluminum as a light emitting host material, and 4,8-bis (4-ethylphenylamino) -1,5- as a light emitting guest material.
1 g of naphthoquinone and bis @ 2- as an electron transport material
1 g of (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene was added, and each was attached to another current-carrying terminal. After evacuating the vacuum layer to 1 × 10 ⁻⁴ Pa, a current was passed through a crucible containing copper phthalocyanine,
Film formation was performed at a deposition rate of 0.3 nm / sec until the film thickness reached 30 nm. An electric current was applied to the crucible containing α-NPD, and a film was formed at a deposition rate of 0.3 nm / sec until the film thickness reached 30 nm.

Next, tris (8-quinolinol) aluminum and 4,8-bis (4-ethylphenylamino)
Each of crucibles containing -1,5-naphthoquinone was energized, and tris (8-quinolinol) aluminum was 0.3
nm / sec, 4,8-bis (4-ethylphenylamino) -1,5-naphthoquinone is 0.02 to 0.03 nm.
The current was controlled so that the deposition rate became / sec, and when both became stable, the deposition was started at the same time. At the stage when the film thickness of tris (8-quinolinol) aluminum was formed to 20 nm, the energization of 4,8-bis (4-ethylphenylamino) -1,5-naphthoquinone was stopped, and tris (8-quinolinol) aluminum was turned off. Only the film having a thickness of 20 nm was continuously formed.

Next, a current was passed through a crucible containing bis {2- (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene, and the film thickness was 30 nm at a deposition rate of 0.4 nm. Film formation was performed until

The supporting substrate thus produced / ITO / α
-NPD / Tris (8-quinolinol) aluminum:
4,8-bis (4-ethylphenylamino) -1,5-
Naphthoquinone / tris (8-quinolinol) aluminum / bis {2- (4-t-butylphenyl) -1,3,3
A cathode was further formed on the device having the structure of 4-oxadiazole 有 す る -m-phenylene in the same manner as in Example 1. Then, as a result of conducting an energization test in the same manner as in Example 1, a current at the time of application of 10 V was 8 mA / cm ² , and a maximum luminance was 5000 cd / m ² (24 V). 400 cd
The chromaticity coordinates at / m ² are (X: 0.630, Y: 0.32
In the red light emission of 3), the luminous efficiency at this time is 0.85 [lm]
/ W].

Further, the above-mentioned element was placed in nitrogen and the initial luminance was 200
As a result of a driving test performed at cd / m ² , the luminance half time was 6
900 hours. Further, the above-described device is
After storage for 00 hours, a non-light-emitting portion called a dark spot was observed. As a result, there was no change from that immediately after the film formation, and no growth was observed.

(Example 4) After a glass substrate with ITO prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, N, N'-diphenyl-N, N '-Di (3-methylphenyl) -1,1'
-Biphenyl-4,4'-diamine (TPD)
mg, 200 mg of tris (8-quinolinol) aluminum as a host and an electron transport layer, 4,4 as a guest
After 100 mg of 8-bis (4-methoxyphenylamino) -1,5-naphthoquinone was charged and attached to an energizing terminal, the inside of the vacuum layer was evacuated to 2 × 10 ⁻⁴ Pa. Then, a current is applied to the board containing the hole injection transport layer, and
The deposition was performed at a deposition rate of nm / sec until the film thickness became 50 nm.

Next, the board containing tris (8-quinolinol) aluminum and 4,8-bis (4-methoxyphenylamino) -1,5-naphthoquinone was energized,
The former is 0.3 nm / sec, and the latter is 0.02-0.03.
Co-deposition was performed at a deposition rate of nm / sec until the thickness reached 30 nm. Subsequently, only tris (8-quinolinol) aluminum was deposited to a thickness of 30 nm.

Next, support substrate / ITO / TPD / tris (8-quinolinol) aluminum: 4,8-bis (4
-Methoxyphenylamino) -1,5-naphthoquinone /
A stainless steel shadow mask was mounted on top of Tris (8-quinolinol) aluminum. Here, 3 g of aluminum was put in a BN boat, and attached to a terminal for energization. Similarly, 500 mg of Li was put into a tungsten filament and attached to another current-carrying terminal. After the vacuum layer was evacuated to 1 × 10 ⁻⁴ Pa, current was supplied so that the deposition rate of aluminum was 0.2 nm / sec, and at the same time, the deposition rate of lithium was 0.02 to 0.03 nm / sec.
It was energized using another deposition power supply so that When the deposition rates of both materials became stable, the shutter was opened, and when the thickness of the mixed film became 20 nm, the lithium vapor deposition power supply was stopped, and an aluminum film was formed to a thickness of 170 nm.

The vacuum layer is returned to the atmospheric pressure again, and the supporting substrate /
ITO / TPD / tris (8-quinolinol) aluminum: 4,8-bis (4-methoxyphenylamino)-
An organic EL device composed of 1,5-naphthoquinone / tris (8-quinolinol) aluminum / AlLi / Al was produced. As a result of applying 10 V with ITO as a positive electrode and an aluminum electrode as a negative electrode, a current of 8.4 mA /
cm ² flow, maximum brightness 5300 cd / m ² (24 V), 4
Chromaticity coordinates at 00 cd / m ² (X: 0.622, Y:
0.320). The luminous efficiency at this time was 0.82 [lm / W]. A driving test was performed on the device in nitrogen at an initial luminance of 200 cd / m ^2. As a result, the luminance half-life was 5,400 hours.

(Embodiment 5) Prepared in the same manner as in Embodiment 1.
After mounting the glass substrate with ITO on the evaporation machine,
Bis @ 2- as an electron transport material in a graphite crucible
(4-t-butylphenyl) -1,3,4-oxadia
Add 1 g of sol｝ -m-phenylene and sprinkle in another crucible
4- [4- (dimethylamino) phenyli as an optical material
Mino] -2-ethylcarbamoyl-1,4-naphthoquino
1 g was added. 1 × 10 vacuum layer ^-FourEvacuated to Pa
Later, 4- [4- (dimethylamino) phenylimino]-
Contains 2-ethylcarbamoyl-1,4-naphthoquinone
Apply current to the crucible and apply a vapor deposition rate of 0.2 nm / sec.
The film was formed to a thickness of 5 nm. Then, screw @ 2-
(4-t-butylphenyl) -1,3,4-oxadia
Apply electricity to the crucible containing sol｝ -m-phenylene,
The film was formed at a deposition rate of 0.4 nm until the film thickness became 50 nm.

Next, the vacuum layer is returned to the atmospheric pressure and the supporting substrate /
ITO / 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone / bis {2- (4-t-butylphenyl) -1,3,4
A cathode was formed on the element having the structure of -oxadiazole｝ -m-phenylene by the same method as in Example 1. E
After the L element was taken out of the evaporator, a current-carrying test was performed in the same manner as in Example 1. As a result, when a voltage of 20 V was applied, 16 m
A current of A / cm ² flowed, and red light emission with a luminance of 140 cd / m ² was obtained.

(Example 6) Except that the light emitting material was 4- (4-dimethylamino-2-methylphenylimino) -2-ethylcarbamoyl-1,4-naphthoquinone,
An organic EL device was manufactured in the same manner as in Example 5. As a result of conducting an energization test in the same manner as in Example 5 using this element,
When a voltage of 20 V was applied, a current corresponding to a current density of 17 mA / cm ² flowed, and red light emission with a luminance of about 130 cd / m ² was obtained.

Example 7 After a glass substrate with ITO prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, (di (p-tolyl) aminophenyl was used as a hole transport layer in a crucible made of high-purity graphite. ) 1,1-cyclohexane
g in a separate crucible as a luminescent material.
-Ethylphenylamino) -1,5-naphthoquinone
g. After the vacuum layer was evacuated to 1 × 10 ⁻⁴ Pa, a current was passed through a crucible containing bis (di (p-tolyl) aminophenyl) -1,1-cyclohexane, and 0.3 nm / sec.
The film was formed at a deposition rate of c until the film thickness became 50 nm. Subsequently, 4,8-bis (4-ethylphenylamino) -1,
The crucible containing 5-naphthoquinone was energized to form a film at a deposition rate of 0.2 nm until the film thickness reached 25 nm.

Next, the supporting substrate / ITO / bis (di (p-
Tolyl) aminophenyl) -1,1-cyclohexane /
4,8-bis (4-ethylphenylamino) -1,5-
A cathode was formed on a device having a naphthoquinone structure in the same manner as in Example 1. After taking out the EL element from the vapor deposition machine, a current-carrying test was performed in the same manner as in Example 1. As a result, when a voltage of 20 V was applied, a current of 21 mA / cm ² flowed, and red light emission with a luminance of 360 cd / m ² was obtained. .

Example 8 The luminescent material was 4,8-bis (4
An organic EL device was produced in the same manner as in Example 5, except that -methoxyphenylamino) -1,5-naphthoquinone was used. A current-carrying test was performed using this device in the same manner as in Example 7, and as a result, the current density was 19 mA /
A current corresponding to cm ² flowed, and red light emission with a luminance of 300 cd / m ² was obtained.

Examples 9 to 12 The same procedures as in Example 1 were carried out except that the luminescent host material was 9,10-bis [4- (diphenylamino) styryl] anthracene (BSA derivative) of the following structural formula (j). An organic EL device was manufactured in the same manner. In this case, an organic EL device was manufactured in the same manner as in Example 3 so that the weight ratio between the light emitting host material and the guest material was as shown in Table 1 below. An energization test was performed in the same manner as in Example 3 using the obtained device. Further, these elements were subjected to a driving test in nitrogen at an initial luminance of 200 cd / m ² , and the luminance half time was determined. As a result, as shown in Table 1, it was confirmed that an organic EL element excellent in efficiency and driving life could be obtained under the above-mentioned manufacturing conditions.

[0067]

Embedded image

[0068]

[Table 1]

(Conventional Example) After a glass substrate with ITO prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, α-NPD was added as a hole transport layer to a crucible made of high-purity graphite.
g of tris (8-quinolinol) aluminum as a light emitting material and an electron transporting material in another crucible,
In another crucible, the following structural formula (k) is used as a dopant.
Of 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-virane (DCM, doping concentration 5 wt%). 1 × 10 ^-4 vacuum layer
After evacuating to Pa, a current was applied to the crucible containing α-NPD, and a film was formed at a deposition rate of 0.3 nm / sec to a thickness of 50 nm.

[0070]

Embedded image

Next, on a board containing tris (8-quinolinol) aluminum and DCM, the former was 0.3 nm /
In the second step, current is supplied to each of the other deposition power supplies so that the deposition rate becomes 0.03 nm / sec. When the deposition rates of both materials become stable, the shutter is opened, and the thickness of the mixed film becomes 30 nm. At that time, the power source for DCM deposition was stopped, and then only tris (8-quinolinol) aluminum was deposited to a thickness of 40 nm.

Next, an element having a structure of support substrate / ITO / α-NPD / tris (8-quinolinol) aluminum: DCM / tris (8-quinolinol) aluminum
A cathode was formed in the same manner as in Example 1. After the EL element was taken out of the vapor deposition machine, a current-carrying test was performed in the same manner as in Example 1. As a result, when a voltage of 6 V was applied, 15 mA / c was obtained.
m ² flows, and the maximum luminance is 12000 cd / m ² (20
V) orange light emission was obtained.

In the above conventional example, the maximum luminance is higher than that of the organic EL device of the present invention, but the chromaticity is C.I. I. Since it is an orange area of (X: 0.528, Y: 0.440) on the E chromaticity coordinates, it becomes white in two colors of blue and blue. Therefore, when the three RGB colors are combined, the color becomes greenish, and white color cannot be obtained. As a result, the conventional organic EL element cannot be used as a full-color display panel element.

[0074]

As described above, the organic EL of the present invention
The element can obtain red light emission with high luminance, high purity, and high efficiency, has a long light emission life, and is therefore effective as a red light emitting element of a color display device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of an organic EL device according to the present invention.

FIG. 2 is a cross-sectional view of an example of the organic EL device according to the present invention.

FIG. 3 is a cross-sectional view of an example of the organic EL device according to the present invention.

FIG. 4 is a sectional view of an example of the organic EL device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent support substrate (glass substrate) 2 Anode 3 Cathode 4 Hole injection layer 5 Hole transport layer 6 Light emitting layer 7 Electron transport layer

Claims (9)

[Claims] 1. An organic electroluminescent device comprising a cathode and an anode and having at least one organic thin film layer including a light emitting layer between the pair of electrodes, wherein at least one of the organic thin film layers has the following structural formula (1) An organic electroluminescent device comprising a naphthoquinone imine compound represented by the formula (1). Embedded image (In the formula, R _{1 to} R ₄ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an aryl group, or a hydroxyl group.) 2. The method of claim 1, wherein the naphthoquinone imine compound represented by the structural formula (1) is 4- [4- (dimethylamino) phenylimino] -2-ethylcarbamoyl-1,4-naphthoquinone or 4- (4-dimethylamino). The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is (-2-methylphenylimino) -2-ethylcarbamoyl-1,4-naphthoquinone. 3. An organic electroluminescent device comprising a cathode and an anode and having at least one organic thin film layer including a light emitting layer between said pair of electrodes, wherein at least one of said organic thin film layers has the following structural formula (2) An organic electroluminescent device comprising a naphthoquinone imine compound represented by the formula (1). Embedded image (Wherein, R _{1 and} R ₂ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, an aryl group, or a hydroxyl group.) 4. The naphthoquinone imine compound represented by the structural formula (2) is 4,8-bis (4-ethylphenylamino) -1,5-naphthoquinone or 4,8-bis (4-methoxyphenylamino) The organic electroluminescence device according to claim 3, wherein the organic electroluminescence device is -1,5-naphthoquinone. 5. The light-emitting layer according to claim 1, wherein the light-emitting layer is a layer containing a naphthoquinone imine compound represented by the structural formula (1) or (2). Organic electroluminescent element. 6. The light emitting layer according to claim 5, wherein said light emitting layer has an EL of 500 nm to 580 nm.
5. A layer containing a green or yellow light-emitting material having a spectrum and a naphthoquinone imine compound represented by the structural formula (1) or (2).
The organic electroluminescent device according to any one of the above items. 7. The method according to claim 1, wherein the naphthoquinone imine compound represented by the structural formula (1) or (2) is contained in a range of 0.001 wt% to 50 wt% with respect to the green and yellow luminescent materials. 7. The organic electroluminescence device according to 6. 8. The light-emitting layer according to claim 1, wherein the light-emitting layer is a layer containing a quinoline-based metal complex and a naphthoquinone imine-based compound represented by the structural formula (1) or (2).
5. The organic electroluminescent device according to any one of items 1 to 4, 9. The light-emitting layer according to claim 1, wherein the light-emitting layer is a layer containing a bisstyrylanthracene derivative and a naphthoquinone imine compound represented by the structural formula (1) or (2). The organic electroluminescence device according to any one of the preceding claims.