JP3452128B2 - Organic electroluminescence device - Google Patents

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 simply referred to as "organic EL device") used for a flat light source or a display device, and more particularly to a red light emitting organic EL device.

[0002]

2. Description of the Related Art Organic EL devices are considered to be promising for use as self-luminous flat display devices. Unlike inorganic EL elements, organic EL elements do not have the constraints of being driven by alternating current and needing high voltage, and due to the variety of organic compounds, it is thought that it is easy to make multiple colors. Is expected to be applied, and is being actively developed.

When the above organic EL device is applied to a full color display, three primary colors, red, green and blue, are used.
It is necessary to obtain color emission.

Many examples of green light emission have been reported. For example, a green device is tris (8-quinolinol).
Devices made of aluminum (Applied Physics Le
ters), 51, 913, 1987) A device using a diarylamine derivative (Japanese Patent Laid-Open No. 8-53397).
No.) etc. have been reported.

As the blue light emitting element, an element using a stilbene compound (JP-A-5-295359) and an element using a triarylamine derivative (JP-A-7-53955).
No.), a device using a tetraaryldiamine derivative (JP-A-8-48656), and a device using a styryl-biphenyl compound (JP-A-6-13080). In addition, using a distyrylarylene derivative as a light emitting material, a luminance of 20,000 cd / m ² or more and a light emitting efficiency of 5
Im / W and half life of 5,000 hours or more have been reported.
(Special Lecture at the 70th Annual Meeting of the Chemical Society of Japan).

Regarding the organic EL device capable of obtaining red light emission, Japanese Patent Application Laid-Open No. 3-152897 discloses a method of wavelength conversion of blue light emission in a fluorescent dye layer.
In JP-A-272854, JP-A-7-288184 or JP-A-8-286033, red light emission is obtained by doping a light-emitting layer capable of emitting green or blue light with a red fluorescent dye. It is not sufficient in terms of brightness and color purity. Further, in JP-A-3-791, an organic EL in which a red fluorescent dye is used alone in a light emitting layer is disclosed.
An element is disclosed, and in JP-A-6-93257, the following structural formula is contained in the light emitting layer.

[0007]

[Chemical 7]

Or

[0009]

[Chemical 8]

Although the use of the squarylium compound as a dopant is disclosed, a sufficient color purity for red light emission has not been obtained, and further improvement is required for practical use.

However, in the method using the color conversion filter, the quantum yield for color conversion of EL emission by the filter is limited, so that sufficient emission efficiency cannot be obtained and the cost of using the filter is low. There was a problem that I could not escape high.

In addition, the red light emitting material exemplified in the above-mentioned conventional example has a low quantum yield of fluorescence and can emit light only with a brightness of about 1000 cd / m ² even if the current flowing inside the device is increased, which is practical. Was lacking.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a red organic EL having high emission brightness, excellent color purity, emission life and the like.

[0014]

The above object can be achieved by the following means. That is, the present invention is an organic electroluminescence device having a cathode, an anode, and at least one organic thin film layer including a light emitting layer between the pair of electrodes, wherein (a) at least one of the organic thin film layers has the following structure: Formula (1)

[0015]

[Chemical 9]

(In the formula, R1 to R3 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted carbon number 1 to
5 represents an alkyl group, a nitro group, a cyano group, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, an aryl group or a halogen atom. ) Or the following structural formula (2)

[0017]

[Chemical 10]

(Wherein R1 to R5 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted carbon number 1 to
5 represents an alkyl group, a nitro group, a cyano group, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, an aryl group, or a halogen atom. (B) The organic electroluminescent device is characterized by containing a squarylium compound represented by
A layer containing a green or yellow light emitting material having an EL spectrum at 0 nm to 580 nm and a squarylium compound represented by the structural formula (1) or the structural formula (2); and (c) the light emitting layer is a host material. And the above structural formula (1) as a guest material
Or a layer containing the squarylium compound represented by the structural formula (2), (d) 0.001 wt% of the squarylium compound represented by the structural formula (1) or the structural formula (2) with respect to the host material % To 50 wt% is included.

[0019]

The present invention will be described in more detail below.

FIG. 1 is a cross-sectional view showing an example of the organic EL element of the present invention. An anode 2 and a cathode 3 provided on a glass substrate 1 are shown.
The hole transport layer 5, the light emitting layer 6, and the electron transport layer 7 are sequentially provided between the above and.

The organic EL device is not limited to the example shown in FIG. 1, but as shown in FIG. 2, the hole injection layer 4, the hole transport layer 5, the light emitting layer 6 and the electron transport layer are provided between the anode 2 and the cathode 3 on the glass substrate 1. A layer 7 and a hole transport layer 5 and a light emitting layer 6 are provided between the anode 2 and the cathode 3 as shown in FIG. 3, and light is emitted between the anode 2 and the cathode 3 as shown in FIG. An example is a structure in which the layer 6 and the electron transport layer 7 are provided.

In the organic EL device of the present invention, the light emitting layer 6 having the above structure has the following structural formula (1).

[0023]

[Chemical 11]

(Wherein R1 to R3 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted carbon number 1 to
5 represents an alkyl group, a nitro group, a cyano group, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, an aryl group or a halogen atom. ) Or the following structural formula (2)

[0025]

[Chemical 12]

(In the formula, R1 to R5 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted carbon number 1 to
5 represents an alkyl group, a nitro group, a cyano group, a substituted or unsubstituted alkoxy group having 1 to 5 carbon atoms, an aryl group, or a halogen atom. ) The squarylium compound represented by the formula (4) is included.

A substituted or unsubstituted carbon number 1 to 1 represented by R1 to R3 in the formula (1) or R1 to R5 in the formula (2).
Examples of the alkyl group of 5 include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl,
Examples thereof include tert-butyl, pentyl, trichloromethyl group and the like. Substituted or unsubstituted carbon number 1 represented by R1 to R3 in formula (1) or R1 to R5 in formula (2)
As the alkoxy group of ~ 5, methoxy, ethoxy, n
-Butoxy, tert-butoxy, trichloromethoxy, trichloroethoxy groups and the like can be mentioned. Examples of the aryl group include a phenyl group and a naphthyl group.

Examples of the above compounds are shown in Table 1, but are not limited to these examples.

[0029]

[Table 1]

Even the compounds in Table 1 have the following structural formulas:

[0031]

[Chemical 13] 2,4-bis-[(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium of the following structural formula

[0032]

[Chemical 14] 2,4-bis [(1-ethyl-3,3-dimethyl-2)
-Indolinylidene) methyl] squarylium is particularly preferable in consideration of luminance, luminous efficiency, luminance half life, and chromaticity coordinates.

The squarylium compound used in the present invention can be obtained by subjecting squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione) and a compound having a corresponding chromophore to a condensation reaction.
For the condensation reaction, it is preferable to use a solvent, for example, alcohols such as methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, the alcohols and benzene, toluene. And mixed solvents of aromatic hydrocarbons such as xylene. The reaction temperature is 7
0-120 degreeC is desirable. For example, 1-propyl alcohol is added to 3,4-dihydroxy-3-cyclobutene-1,2-dione and heated to about 100 ° C. Then (1,
3,3-Trimethyl-2-indolinylidene) methyl and toluene are added and reacted, and after cooling, purification by column chromatography gives R1 and R in the structural formula (2).
_{2, R3 = CH 3, R4} , R5 = squarylium compound of H are obtained.

As the host material of the light emitting layer, the following structural formula is used.

[0035]

[Chemical 15] 8-hydroxyquinoline metal complex represented by tris (8-quinolinol) aluminum, 1,4-bis (2
-Methylstyryl) benzene and other distyrylbenzene derivatives, bisstyrylanthracene derivatives, coumarin derivatives, oxathiazole derivatives, perinone derivatives, and the like. Representative 8-hydroxyquinoline metal complexes, coumarin derivatives and the like are particularly preferable because high luminance and luminous efficiency can be obtained.

In the light emitting layer, it is also possible to use the squarylium compound as a mixture of another hole transporting material, an electron transporting material and a light emitting material.

The above-mentioned squarylium compound must be mixed in the range of 0.001 wt% to 50 wt% with respect to the host material of the light emitting layer. The amount of squarylium mixed is 0.
If less than 001 wt%, there is a problem that chromaticity deteriorates.
If it exceeds wt%, concentration quenching and a decrease in luminous efficiency occur, 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 4 of the organic EL device according to the present invention is not particularly limited and may be represented by the following structural formula.

[0040]

[Chemical 16] Metal-free phthalocyanine (X is hydrogen, M
-Y is Cu, VO, TiO, Mg, is selected from H _2. ), 4,4 ′, 4 ″ -tris (diphenylamino)
Starburst type molecules such as triphenylamine

[0041]

[Chemical 17] The compound shown by can be used.

Further, the hole transport material for forming the hole transport 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 transport material. is there.

For example, the following structural formula

[0044]

[Chemical 18] Bis (di (p-tolyl) aminophenyl)-
1,1-cyclohexane, the following structural formula

[0045]

[Chemical 19] Represented by N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,
4'-diamine, the following structural formula

[0046]

[Chemical 20] Represented by N, N′-diphenyl-N, N′-bis (1-naphthyl)-(1,1′-biphenyl) -4,
4'-diamine starburst type molecule or the following structural formula

[0047]

[Chemical 21] And the like.

Further, the electron transport material for forming the electron transport layer of the organic EL device of the present invention is not particularly limited, and any electronic material can be used as long as it is a compound usually used as the electron transport material. is there.

For example, the following structural formula

[0050]

[Chemical formula 22]

2- (4-biphenyl) -5 represented by
(4-t-butylphenyl) -1,3,4-oxadiazole, the following structural formula

[0052]

[Chemical formula 23]

Oxadiazole derivatives such as bis {2- (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene represented by: triazole derivatives, oxine metal complexes, pyrazine derivatives , Pyridine derivatives, perylene derivatives, perinone derivatives, bissteryl derivatives and the like.

Examples of the material of the anode include transparent materials having a large work function, examples of which include conductive metal oxides such as indium tin oxide (ITO), tin oxide and indium oxide, gold, platinum and chromium. Examples of materials for the cathode include metals having a small work function, and alloys of the above metals with alkali metals and alkaline earth metals, such as aluminum, silver, tin, and alloys of these with lithium, magnesium, potassium, sodium and the like.

When co-evaporating the squarylium derivative and another material in forming the light emitting layer, it is important to pay attention to the doping concentration and position.

[0056]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 A sectional structure of an organic EL device according to Example 1 is shown in FIG. The organic EL device according to the present 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. It consists of 5-7. Less than,
A procedure for manufacturing the organic EL element according to Example 1 will be described. First, ITO was sputtered on a glass substrate to form a film having a sheet resistance of 15 Ω / □ or less, thereby forming an anode 2. After ultrasonic cleaning the glass with ITO with pure water and isopropyl alcohol,
Further dried over boiled isopropyl alcohol. Furthermore, this substrate is cleaned with a UV ozone cleaning device,
It was attached to a substrate holder of a vacuum vapor deposition device.

The hole transporting layer 5 is formed on the molybdenum board as N, N'-diphenyl-N, N'-bis (α-
Naphthyl) -1,1′-biphenyl-4,4′-diamine (abbreviated as α-NPD) 200 mg, tris (8-quinolinol) aluminum (abbreviated as Alq3) as a host of the light emitting layer 6 and the electron transport layer 7. 200 mg, and 100 mg of 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium as a guest of the light emitting layer, and after attaching this to a current-carrying terminal, a vacuum chamber The inside was evacuated to 2 × 10 ⁻⁴ Pa. Then, energize the board containing α-NPD, 0.3 nm
Vapor deposition was performed at a vapor deposition rate of / Sec to a film thickness of 50 nm. Next, tris (8-quinolinol) aluminum,
A board containing 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium has the former of 0.3 nm / Sec and the latter of 0.02-
It is energized by using another vapor deposition power source so that the rate becomes 0.03 nm / Sec, the shutter is opened when the vapor deposition rate of both materials becomes stable, and 2,4-bis [] is obtained when the film thickness of the mixed film becomes 30 nm. The deposition power source of (1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium was stopped, and then only tris (8-quinolinol) aluminum was deposited to a thickness of 30 nm.

Next, supporting substrate / ITO / α-NPD / tris (8-quinolinol) aluminum: 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium / Tris. A stainless shadow mask was attached to the top of the (8-quinolinol) aluminum. Here, 3 g of aluminum was put into a BN boat and attached to the energizing terminal. Similarly, 500 mg of Li was put into a tungsten filament and attached to another energizing terminal. After evacuating the vacuum chamber to 1 × 10 ⁻⁴ Pa, the deposition rate of aluminum is 0.2 nm / S.
The current was applied so as to obtain ec, and at the same time, the current was supplied using another vapor deposition power source so that the deposition rate of lithium was 0.02 to 0.03 nm / Sec. When the deposition rate of both materials became stable, the shutter was opened and the mixed film thickness was 20 nm.
At that point, the evaporation power source for lithium was stopped, and an aluminum film was formed to a film pressure of 170 nm to form the cathode 3. Return the vacuum chamber to atmospheric pressure, and then support substrate / ITO /
α-NPD / tris (8-quinolinol) aluminum: 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl)] squarylium / tris (8-quinolinol) aluminum / AlLi / A
An organic EL device consisting of 1 was prepared. ITO of this element
With a positive electrode and an aluminum electrode as a negative electrode, the current when 10 V is applied is 9 mA / cm ² , and the maximum brightness is 5900 cd / m ² (24
V) was obtained. The chromaticity coordinate at 400 cd / m ² is (X
0.641, Y 0.328), and the luminous efficiency at this time was 0.83 lm / W (lumens / watt).

This element was placed in nitrogen and the initial luminance was 400 cd /
As a result of a driving test at m ² , the luminance half-life was 2300 hours.

After the element was stored in nitrogen for 5000 hours, a non-light emitting portion called a dark spot was observed. As a result, no change was observed immediately after 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 was used as a hole injecting and transporting material on a molybdenum board. '-Di (3-methylphenyl) -1,
2'of 1'-biphenyl-4,4'-diamine (TPD)
00 mg, Tris (8 as host and electron transport layer
-Quinolinol) aluminum (200 mg) and 2,4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl] squarylium as guest (1)
After the amount of 00 mg was charged and this was attached to a current-carrying terminal, the inside of the vacuum chamber was evacuated to 2 × 10 ⁻⁴ Pa. Then, the board containing the hole injecting and transporting layer was energized, and vapor deposition was performed at a vapor deposition rate of 0.3 nm / Sec to a film thickness of 50 nm. next,
Tris (8-quinolinol) aluminum, and 2,
The board containing 4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl] squarylium was energized to 0.3 nm / Sec for the former and 0.02 for the latter.
Co-evaporation was performed at a vapor deposition rate of 0.03 nm / Sec to 30 nm. Subsequently, only tris (8-quinolinol) aluminum was vapor-deposited with a thickness of 30 nm.

Next, supporting substrate / ITO / TPD / tris (8-quinolinol) aluminum: 2,4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl] squarylium / Tris ( 8-quinolinol) A stainless shadow mask was attached on top of the aluminum. Here, 3 g of aluminum was put into a BN boat and attached to the energizing terminal. Similarly, 500 mg of Li was put into a tungsten filament and attached to another energizing terminal. After the vacuum chamber was evacuated to 1 × 10 ⁻⁴ Pa, the deposition rate of aluminum was 0.2 nm / Se.
The current was applied so as to obtain c, and at the same time, the current was supplied using another vapor deposition power source so that the deposition rate of lithium was 0.02 to 0.03 nm / Sec. When the deposition rate of both materials became stable, the shutter was opened and the mixed film thickness was 20 nm.
At that point, the deposition power source for lithium was stopped, and an aluminum film was formed to a film thickness of 170 nm. again,
The vacuum chamber was returned to atmospheric pressure, and the supporting substrate / ITO / TPD / tris (8-quinolinol) aluminum: 2,4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl)] squarylium / Tris (8-quinolinol) aluminum / AlLi / Al organic E
An L element was produced. As a result of applying 10 V with ITO of this element as a positive electrode and an aluminum electrode as a negative electrode, the current was 8 m.
A / cm ² flow, maximum brightness 5500 cd / m ² (24V),
Chromaticity coordinates at 400 cd / m ² (X 0.619, Y
A red emission of 0.340) was obtained. At this time, the luminous efficiency was 0.78 lm / W.

This device was subjected to an initial luminance of 400 cd / in nitrogen.
As a result of a driving test at m ² , the luminance half-life was 2300 hours.

After the element was stored in nitrogen for 5000 hours, a non-light emitting portion called a dark spot was observed. As a result, no change was observed immediately after film formation and no growth was observed.

(Example 3) The 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 separately prepared as a hole injection layer. 1 g, and N, N′-diphenyl-N, N′-bis (α-naphthyl) -1,1′-biphenyl-4,4′-diamine (α
-NPD), 1 g of tris (8-quinolinol) aluminum as a light emitting host material, and 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium as a light emitting guest material. 1
g, and 1 g of bis {2- (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene as an electron transport material were put therein and attached to separate current-carrying terminals.

After evacuating the vacuum chamber to 1 × 10 ^-4 Pa,
Energize the crucible containing copper phthalocyanine to 0.3 nm
The film was formed at a vapor deposition rate of / Sec until the film thickness became 30 nm. Energize the crucible containing α-NPD to 0.3 nm /
A film was formed at a deposition rate of Sec until the film thickness became 30 nm.
Next, electricity was applied to the crucibles containing tris (8-quinolinol) aluminum and 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl)] squarylium, respectively, and tris (8- Quinolinol)
Aluminum is 0.3 nm / Sec, and 2,4-bis [(1,3,3-trimethyl-2-benzoindorylidene) methyl] squarylium 0.02-0.03n
The current was controlled so as to be m / Sec, and when both were stable, vapor deposition was started at the same time. When the film thickness of tris (8-quinolinol) aluminum was 20 nm, 2,4-bis [(1,3,3-trimethyl-2-
The energization of benzoindolinylidene) methyl] squarylium was stopped, and a film of tris (8-quinolinol) aluminum alone was continuously formed to a thickness of 20 nm.

Next, the crucible containing bis {2- (4-t-butylphenyl) -1,3,4-oxadiazole} -m-phenylene was energized to form a film with a deposition rate of 0.4 nm and a film thickness of 30 nm. The film was formed until it became.

Support substrate / ITO / copper thus produced
Phthalocyanine / α-NPD / Tris (8-quinolino
Ru) Aluminum: 2,4-bis [(1,3,3-tri
Methyl-2-benzoindolinylidene) methyl] squa
Lilium / Tris (8-quinolinol) aluminum /
Bis {2- (4-t-butylphenyl) -1,3,4-
An element having the structure of oxadiazole} -m-phenylene
Further, a cathode is formed on the child by the same method as in Example 1.
(Fig. 2). Then, the energization test is performed in the same manner as in Example 1.
As a result, the current when applying 10 V is 8 mA / cm², Maximum brightness
5300 cd / m ²(24V) was obtained. 400 cd /
m²The chromaticity coordinate at the time is (X 0.630, Y 0.347)
It emits red light, and the luminous efficiency at this time is 0.80 lm / W.
there were. Initial brightness of this device was 400 cd / m in nitrogen.²so
As a result of the driving test, the luminance half time is 2900 hours.
there were.

After the element was stored in nitrogen for 5000 hours, a non-light emitting portion called a dark spot was observed. As a result, no change was observed immediately after film formation and no growth was observed.

(Example 4) 2,4-bi
Sus [(1-ethyl-3,3-dimethyl-2-indolini
Example 3 except that [liden) methyl] squarylium was used.
An organic EL device was produced in the same manner as in. Implement this element
When conducting an energization test in the same manner as in Example 1, when 10 V was applied, current density was reduced.
8mA / cm²A current equivalent to flows, and the maximum brightness is about 50
00 cd / m ², 400 cd / m²The chromaticity coordinate at the time is (X
A red emission of 0.610, Y 0.345) was obtained.

Example 5 A glass substrate with ITO prepared in the same manner as in Example 1 was mounted on a vapor deposition machine, and then a bis (di (p (p)
1 g of -tolyl) aminophenyl) -1,1-cyclohexane was placed in another crucible as a luminescent material, and 1 g of 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium was used as a luminescent material. I put it in. After the vacuum chamber was evacuated to 1 × 10 ⁻⁴ Pa, the crucible containing bis (di (p-tolyl) aminophenyl) -1,1-cyclohexane was energized to form a film at a deposition rate of 0.3 nm / Sec. The film was formed to a thickness of 50 nm. Then, the crucible containing 2,4-bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl] squarylium was energized to form a film at a deposition rate of 0.2 nm until the film thickness reached 25 nm. did. Next, support substrate / ITO / bis (di (p-tolyl)
Aminophenyl) -1,1-cyclohexane / 2,4-
A cathode having a bis [(1,3,3-trimethyl-2-benzoindolinylidene) methyl)] squarylium structure was formed by a method similar to the method of Example 1 (FIG. 3). After taking out the EL device from the vapor deposition machine, a current-carrying test was carried out in the same manner as in Example 1. As a result, when a voltage of 20 V was applied, a current of 5.0 mA / cm ² flowed and a luminance of 390 c was obtained.
A red emission of d / m ² was obtained.

Example 6 Organic compound was prepared in the same manner as in Example 5 except that 2,4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl] squarylium was used as the light emitting material. An EL device was produced. When an energization test was conducted on this element in the same manner as in Example 5, when a voltage of 20 V was applied, a current corresponding to a current density of 4.6 mA / cm ² flowed, and a luminance of 350 was obtained.
A red emission of cd / m ² was obtained.

Example 7 Prepared in the same manner as in Example 1.
After mounting the glass substrate with ITO on the vapor deposition machine,
In the crucible made of Laphite, as a material for electron transport, bis {2-
(4-t-butylphenyl) -1,3,4-oxadia
1g of sol} -m-phenylene is put into another crucible.
2,4-bis [(1,3,3-trimethyl) as an optical material
-2-Benzindolinylidene) methyl] squariliu
I put 1g of mu. 1 x 10 vacuum chamber ^-FourExhausted to Pa
Then, 2,4-bis [(1,3,3-trimethyl-2-beta)
Nzoindolinylidene) methyl] squarylium
Energize the crucible and apply 2 at a deposition rate of 0.2 nm / Sec.
The film was formed to a film thickness of 5 nm. Then screw {2-
(4-t-butylphenyl) -1,3,4-oxadia
Sol} -m-Phenylene in a crucible is energized and steamed
A film was formed at a deposition rate of 0.4 nm to a film thickness of 50 nm.
Next, the vacuum chamber is returned to atmospheric pressure, and the supporting substrate / ITO / 2,4
-Bis [(1,3,3-trimethyl-2-benzoindo
Vinylidene) methyl)] squarylium / bis {2-
(4-t-butylphenyl) -1,3,4-oxadia
Example 1 for a device having a structure of sol} -m-phenylene
A cathode was formed by a method similar to the method (FIG. 4). E
After taking out the L element from the vapor deposition machine, the same procedure as in Example 1 was performed.
As a result of an electric test, when a voltage of 20 V was applied, 4.1
mA / cm²Current flows and the brightness is 160 cd / m²From red
Got the light.

Example 8 An organic EL device was manufactured in the same manner as in Example 7 except that 2,4-bis [(1-ethyl-3,3-dimethyl-2-indolinylidene) methyl] squarylium was used as the light emitting material. A device was produced. When an energization test was conducted on this element in the same manner as in Example 7, when a voltage of 20 V was applied, a current corresponding to a current density of 5 mA / cm ² flowed and the brightness was about 150 cd.
A red emission of / m ² was obtained.

Examples 9 to 12 EL devices were manufactured by the same method as in Example 1 except that the light emitting host material was a bisstyrylanthracene (BSA) derivative. An EL device was produced in the same manner as in Example 3 such that the weight ratio of the light emitting host material and the guest material was under the conditions shown in Table 2. An energization test was performed on these devices in the same manner as in Example 3. Furthermore, this element was exposed to nitrogen in an initial luminance of 400 cd / m ²
The drive test was carried out in order to determine the luminance half time. As a result, as shown in Table 2, under these manufacturing conditions, an element excellent in efficiency and driving life can be obtained.

[0077]

[Table 2]

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

Then, the former was placed on a board containing tris (8-quinolinol) aluminum and DCM at 0.3 nm /
Sec and the latter were each energized using another vapor deposition power source so as to be 0.03 nm / Sec, the shutter was opened when the vapor deposition rate of both materials became stable, and DCM was reached when the film thickness of the mixed film reached 30 nm. Turn off the evaporation power supply of
Subsequently, only tris (8-quinolinol) aluminum was deposited to a thickness of 40 nm.

Then, a cathode was formed on the device having the structure of supporting substrate / ITO / α-NPD / tris (8-quinolinol) aluminum: DCM / tris (8-quinolinol) aluminum by the same method as in Example 1. did. E
After taking out the L element from the vapor deposition machine, a current-carrying test was conducted in the same manner as in the example. As a result, when a voltage of 6 V was applied, it was 15 mA.
A current of / cm ² was flowed, and an orange light emission with a maximum brightness of 12000 cd / m ² was obtained.

The maximum brightness is higher than that of the organic EL device of the present invention, but the chromaticity is C.I. I. On the E chromaticity coordinate (X 0.52
(8, Y 0.440), which is an orange region, so that two colors, blue, become white. Therefore, RGB3
When the colors were matched, a greenish color was obtained, and white could not be obtained. As a result, it could not be used as a device for a full-color display panel.

[0082]

The red light emitting material of the present invention has absorption in the green region and exhibits fluorescence with a high quantum yield in the red region of 600 to 650 nm. Therefore, by using the light emitting material of the present invention, organic EL It is possible to obtain the red light emission required for colorizing the device with high brightness and high efficiency.

Furthermore, since this material has a high quantum yield, it is possible to obtain light emission in the red region with high brightness by mixing in a small amount in the light emitting layer of the organic EL element.
It does not hinder the movement of carriers injected into the L element. In addition, this material can be easily made into a thin film by the resistance heating type film forming method, the thin film state is extremely stable and excellent in flatness, and changes in the film structure such as crystallization and formation of aggregated state are recognized. Therefore, it is easy to extend the life of the organic EL element.

From the above, organic EL using the material of the present invention
The element is effective as a red light emitting element of a color display device.

[Brief description of drawings]

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

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

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

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

[Explanation 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 (6)

(57) [Claims] 1. In an organic electroluminescence device having a cathode, an anode, and 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 structure as a guest material. Formula (1) (Wherein R1 to R3 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-5 alkyl group, a nitro group, a cyano group, a substituted or unsubstituted C1-5 alkoxy group, Represents a aryl group or a halogen atom) and 500 nm
A red light emitting organic electroluminescence device comprising a host material having an EL spectrum at ˜580 nm. 2. The luminescent layer comprises a quinoline-based metal complex as a host material and the structural formula (1) as a guest material.
The red light emitting organic electroluminescent device according to claim 1, which is a layer containing a squarylium compound represented by: 3. The squarylium compound represented by the structural formula (1) in an amount of 0.001 wt% to the host material.
The red light emitting organic electroluminescence device according to claim 1, wherein the red light emitting organic electroluminescence device is contained in a range of 50 wt%. 4. An organic electroluminescence device having a cathode, an anode, and 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 structure as a guest material. Formula (2) (Wherein R1 to R5 are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-5 alkyl group, a nitro group, a cyano group, a substituted or unsubstituted C1-5 alkoxy group, An aryl group or a halogen atom) and a squarylium compound of 500 nm
A red light emitting organic electroluminescent device comprising a host material having an EL spectrum at 580 nm. 5. The luminescent layer comprises a quinoline-based metal complex as a host material and the structural formula (2) as a guest material.
The red light emitting organic electroluminescence device according to claim 4, which is a layer containing a squarylium compound represented by: 6. The squarylium compound represented by the structural formula (2) is added in an amount of 0.001 wt% to the host material.
The red light emitting organic electroluminescence device according to claim 4, wherein the red light emitting organic electroluminescence device is contained in a range of 50 wt%.