JP5750821B2 - Organic compound, organic electroluminescent element material, composition for organic electroluminescent element, organic electroluminescent element, organic EL display device, and organic EL lighting - Google Patents

Description

  The present invention is a compound useful as a charge transport material suitably used for an organic electroluminescence device having high luminous efficiency and excellent driving life including heat resistance, and can be suitably used for a wet film-forming method, The present invention relates to an organic compound having high solubility in an organic solvent.

  In recent years, as a thin film type electroluminescent element, an organic electroluminescent element using an organic thin film has been developed instead of using an inorganic material. Organic electroluminescent devices are usually formed by providing a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, etc. between the anode and the cathode, and materials suitable for each layer are being developed. . In addition, the light emission colors of organic electroluminescent elements are being developed in red, green, and blue, respectively.

However, blue organic electroluminescent elements have not been satisfactory in terms of efficiency, life, and heat resistance, and there is a problem that application to full color display is limited.
As a method for forming each constituent layer of the organic electroluminescent element, there are a vacuum vapor deposition method and a wet film formation method. Among these, the vacuum deposition method has a problem in terms of yield when manufacturing a medium- or large-sized full-color panel for a television or a monitor. Therefore, the wet film-forming method is suitable for these large area applications.

However, in order to form an organic layer of an organic electroluminescent element by a wet film formation method, the material for forming the organic layer is dissolved in a solvent, and the high performance required as a component layer of the element after the wet film formation is obtained. It is desirable to have. However, even materials that have been conventionally developed for wet film formation methods often do not satisfy the conditions required for such wet film formation methods.
For example, Patent Document 1 discloses an element manufactured by a wet film formation method using a material represented by the following formula.

  Patent Document 2 discloses an element manufactured by a wet film forming method using a material represented by the following formula.

  However, these materials do not satisfy the physical properties required in the process of wet film formation such as solubility in solvents and heat resistance, and the driving voltage is high or sufficient life is not obtained even when used in an element. There were problems such as. Patent Document 3 describes an element formed by vapor deposition using (A-1) and (A-2) and Patent Document 4 (A-3) as a charge transport material. is there.

International Publication No. 2006/070712 Pamphlet JP 2004-224766 A JP 2005-314239 A International Publication No. 2005-11353 Pamphlet

The present invention is an organic compound that is soluble in various solvents and that can form an organic layer of an organic electroluminescent device by a wet film forming method to produce an organic electroluminescent device having a low driving voltage and a sufficient lifetime. And an organic electroluminescent element having an organic layer formed by a wet film-forming method using the composition for organic electroluminescent element, and an organic EL including the organic electroluminescent element
It is an object to provide a display device and organic EL lighting.

As a result of intensive studies by the present inventors, the reason why the drive life of the device is not sufficient is presumed to be due to a decrease in recombination probability with holes due to fast movement of electrons in the light emitting layer. did.
As a result of further studies, the inventors have found that the above problem can be solved by adjusting the electron transfer ability of the compound by using a compound having a specific structure, and have reached the present invention.
That is, the present invention is represented by the following formula (1): an organic compound, an organic electroluminescent element material, an organic electroluminescent element composition, an organic electroluminescent element, an organic EL display device, and an organic It exists in EL lighting.

(In the formula, Ar ¹ substituted by Table also aromatic ring, R ¹ and R ^2, a naphthalene ring bonded to together with ring A together, phenanthrene ring, or form a quinoline ring To do.

n represents an integer of 0 to 2.
Moreover, the dibenzofuran ring, the anthracene ring, and the benzene ring in a formula may have a substituent other than a connection part. )

The organic compound of the present invention has steric hindrance at a portion other than the anthracene ring, so that it has excellent redox durability and appropriate charge mobility, and has both high solubility in an organic solvent. .
Therefore, the organic electroluminescence device having the layer containing the organic compound of the present invention has a low driving voltage and a long driving life.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.
[Explanation of words]
In the present invention, the simple term “aromatic ring” includes both an aromatic hydrocarbon ring and an aromatic heterocyclic ring.

In the present invention, the term “(hetero) aryl” includes both an aromatic hydrocarbon ring and an aromatic heterocycle.
In the present invention, “may have a substituent” means that one or more substituents may be present.
<Organic compounds>
The organic compound of the present invention is an organic compound represented by the following formula (1).

(In the formula, Ar ¹ represents an aromatic ring which may have a substituent,
R ¹ represents an arbitrary substituent having 1 or more carbon atoms, R ² represents a hydrogen atom or an arbitrary substituent, and R ¹ and R ² may be bonded to each other to form a ring.
Ring A represents a 5- or 6-membered aromatic ring. However, ring A may have a substituent other than R ¹ and R ² .

n represents an integer of 0 to 2.
Moreover, the dibenzofuran ring, the anthracene ring, and the benzene ring in a formula may have a substituent other than a connection part. )
[Structural features]
The reason why the organic compound of the present invention is excellent in oxidation-reduction durability, has a moderately adjusted charge mobility, and has a high solubility in an organic solvent is presumed as follows.

The organic compound of the present invention contains an anthracene ring having redox durability and electron transfer ability and a dibenzofuran ring having hole transfer ability.
When this anthracene ring and other partial structures cause steric hindrance (strain) in the molecule, the excitation energy is concentrated on the anthracene ring. Thereby, energy transfer from the anthracene ring to a group bonded in the vicinity of the strain generation site occurs, and the anthracene ring and the group are cleaved. As a result, charge durability and charge mobility are lowered.

On the other hand, in the organic compound of the present invention, steric hindrance occurs between the benzene ring bonded to the ring A at the m-position and R ¹ bonded to the o-position of the ring A. That is, the anthracene ring and other partial structures do not cause steric hindrance. As a result, the organic compound of the present invention is not easily dissociated from the anthracene ring and has good redox durability. Further, due to steric hindrance, the organic compound of the present invention has good solubility in an organic solvent.

In addition, by-(Ar ¹ ) n-phenyl group-ring A, the intermolecular distance of an anthracene ring-anthracene ring from a neighboring molecule can be increased, and the electron mobility can be adjusted.
As a result of adjusting the electron mobility, the recombination probability between holes and electrons is increased in the light emitting layer, so that the light emitting efficiency of the resulting device is increased and the driving life is long.
Further, it is preferable to increase the probability of bond cleavage by energy transfer from anthracene by separating the distance between the steric hindrance and the anthracene ring.

As described above, by using the organic compound of the present invention in the organic layer of the organic electroluminescent element formed by the wet film forming method, the durability of the organic electroluminescent element is improved, the driving voltage is lowered, and the lifetime is improved.
The wet film forming method in the present invention is a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, a capillary coating method, an ink jet method, a screen printing method, A gravure printing method, flexographic printing method, offset printing method, or the like is a method for forming a film using an ink containing a solvent. Of these, the die coating method, the roll coating method, the spray coating method, the ink jet method, and the flexographic printing method are preferable from the viewpoint of easy patterning.

Hereinafter, each component in the above formula (1) will be described in detail.
[About Ar ¹ ]
Ar ¹ represents an aromatic ring which may have a substituent.
As the aromatic ring, those having 30 or less carbon atoms are preferable. For example, aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, naphthacene ring, chrysene ring, pyrene ring, triphenylene ring, coronene ring, and thiophene ring , Furan ring, pyrrole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, quinoline ring, isoquinoline ring, indole ring, benzothiophene ring, benzofuran ring, dibenzofuran ring, dibenzothiophene ring, carbazole ring, etc. Is mentioned. Of these, a benzene ring, a naphthalene ring, a pyridine ring, a dibenzofuran ring and a dibenzothiophene ring are preferable, a benzene ring and a naphthalene ring are particularly preferable, and a benzene ring is most preferable from the viewpoint of the stability of the compound.

Ar ¹ may have a substituent, and examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 25 carbon atoms, and an aromatic group having 3 to 20 carbon atoms. A heterocyclic group, an alkoxy group having 1 to 20 carbon atoms, a (hetero) aryloxy group having 3 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, a (hetero) arylthio group having 3 to 20 carbon atoms, and a cyano group. Can be mentioned.

Among these, as a substituent which Ar < ¹ > has, the C1-C20 alkyl group and C6-C25 aromatic hydrocarbon group are preferable from the surface of the stability of a compound, C6-C25 aromatic A group hydrocarbon group is particularly preferred.
As more specific examples of a preferable Ar ¹ is the substituent which may have, include the following.

[Substituent group Z]
Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, iso-butyl group, sec-butyl group, tert-butyl group, hexyl group, octyl group and cyclohexyl group. Group, decyl group, octadecyl group and the like. Among these, Preferably, they are a methyl group, an ethyl group, and an isopropyl group, and a methyl group and an ethyl group are preferable from the point of being easy to obtain a raw material and cheap, and an iso-butyl group and a sec-butyl group. , Tert-butyl group is preferable because of its high solubility in nonpolar solvents.

Examples of the aromatic hydrocarbon group having 6 to 25 carbon atoms include a naphthyl group such as a phenyl group, a 1-naphthyl group and a 2-naphthyl group, a phenanthyl group such as a 9-phenanthyl group and a 3-phenanthyl group, and 1-anthryl. Group, 2-anthryl group, anthryl group such as 9-anthryl group, 1-naphthacenyl group, naphthacenyl group such as 2-naphthacenyl group, 1-chrysenyl group, 2-chrysenyl group, 3-chrysenyl group, 4-chrysenyl group, 5-chrycenyl group, 6-chrycenyl group and other chrycenyl groups, 1-pyrenyl group and other pyrenyl groups, 1-triphenylenyl group and other triphenylenyl groups, 1-coronenyl group and other coronenyl groups, 4-biphenyl group,
And biphenyl groups such as 3-biphenyl group. From the viewpoint of stability of the compound, phenyl group, 2-naphthyl group, 1-anthranyl group, 9-phenanthryl group, 9-anthranyl group, 4-biphenyl group, 3- A biphenyl group is preferable, and a phenyl group, a 2-naphthyl group, and a 3-biphenyl group are particularly preferable because of easy purification of the compound.

  Examples of the aromatic heterocyclic group having 3 to 20 carbon atoms include thienyl group such as 2-thienyl group, furyl group such as 2-furyl group, imidazolyl group such as 2-imidazolyl group, and carbazolyl such as 9-carbazolyl group. Groups, pyridyl groups such as 2-pyridyl group, triazin-yl groups such as 1,3,5-triazin-2-yl group, and the like. Of these, a 9-carbazolyl group is preferable from the viewpoint of stability of the compound.

Examples of the alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, isopropyloxy group, cyclohexyloxy group, octadecyloxy group and the like.
Examples of the (hetero) aryloxy group having 3 to 20 carbon atoms include phenoxy group, 1-naphthyloxy group, 9-anthranyloxy group, 2-thienyloxy group and the like.
Examples of the alkylthio group having 1 to 20 carbon atoms include methylthio group, ethylthio group, isopropylthio group, cyclohexylthio group and the like.

Examples of the (hetero) arylthio group having 3 to 20 carbon atoms include a phenylthio group, a 1-naphthylthio group, a 9-anthranylthio group, and a 2-thienylthio group.
n represents an integer of 0 to 2.
n is preferably 1 to 2 in terms of improving the durability of the compound by separating a bond site having a large strain from the anthracene ring, and 0 is particularly preferable in terms of improving the solubility in organic solvents and the film forming property.

Moreover, the molecular weight of the moiety represented by (Ar ¹ ) _n including its substituents is usually 700 or less, preferably 500 or less, more preferably 200 or less, and usually 0 or more.
Within the above range, it is preferable in terms of easy purification of the compound.
[About Ring A]
Ring A represents a 5- or 6-membered aromatic ring.

  The aromatic ring of ring A is preferably an aromatic ring having 30 or less carbon atoms, for example, an aromatic hydrocarbon ring such as a benzene ring, naphthalene ring, anthracene ring, naphthacene ring, chrysene ring, pyrene ring, triphenylene ring, coronene ring, Aromatics such as thiophene ring, furan ring, pyrrole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, quinoline ring, isoquinoline ring, indole ring, benzothiophene ring, benzofuran ring, dibenzofuran ring, dibenzothiophene ring, carbazole ring Heterocycle etc. are mentioned.

Of these, a benzene ring, a naphthalene ring, a pyridine ring, a dibenzofuran ring and a dibenzothiophene ring are preferable, a benzene ring and a naphthalene ring are particularly preferable, and a benzene ring is most preferable from the viewpoint of the stability of the compound.
[About R ¹ and R ² ]
R ¹ represents an arbitrary substituent having 1 or more carbon atoms, and R ² represents a hydrogen atom or an arbitrary substituent. R ¹ and R ² may be bonded to each other to form a ring.

Specific examples of R ¹ include an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 25 carbon atoms, an aromatic heterocyclic group having 3 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, Examples thereof include a (hetero) aryloxy group having 3 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, a (hetero) arylthio group having 3 to 20 carbon atoms, and a cyano group. Among these, an alkyl group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 25 carbon atoms are preferable, and an aromatic hydrocarbon group is particularly preferable from the viewpoint of the stability of the compound.

Specific examples of R ² include a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 25 carbon atoms, an aromatic heterocyclic group having 3 to 20 carbon atoms, and an alkyl group having 1 to 20 carbon atoms. Examples thereof include an alkoxy group, a (hetero) aryloxy group having 3 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, a (hetero) arylthio group having 3 to 20 carbon atoms, and a cyano group. Of these, a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aromatic hydrocarbon group having 6 to 25 carbon atoms are preferable, and a hydrogen atom and an aromatic hydrocarbon group are particularly preferable from the viewpoint of stability of the compound.

A preferred combination of R ¹ and R ^{2 is} a combination in which R ¹ is an aromatic hydrocarbon group and R ² is a hydrogen atom, more preferably a group in which R ¹ and R ² are bonded to each other to form a ring. is there.
Examples of the group in which R ¹ and R ² are bonded to each other to form a ring include a naphthalene ring, a phenanthrene ring, and a quinoline ring together with ring A.

Ring A may have a substituent other than R ¹ and R ² as long as the effects of the present invention are not impaired. Examples of the substituent that the ring A may have other than R ¹ and R ² include the same groups as those described in the above-mentioned section [about R ¹ and R ² ].
However, ring A preferably has no substituent other than R ¹ and R ^{2 in} terms of oxidation-reduction durability.

[Dibenzofuran ring and anthracene ring]
The anthracene ring and dibenzofuran ring may have a substituent.
The substituent that the anthracene ring and dibenzofuran ring may have is preferably a substituent having 50 or less carbon atoms, and the substituent may further have a substituent.
Specific examples of the substituent that the anthracene ring and dibenzofuran ring may have include an alkyl group having 1 to 20 carbon atoms, an aromatic hydrocarbon ring group having 6 to 25 carbon atoms, and an aromatic group having 3 to 20 carbon atoms. Heterocyclic group, C1-C20 alkoxy group, C3-C20 (hetero) aryloxy group, C1-C20 alkylthio group, C3-C20 (hetero) arylthio group, cyano group, etc. Is mentioned. Among these, as a substituent which an anthracene ring has, from the surface of stability of a compound, a C1-C20 alkyl group, a C6-C25 aromatic hydrocarbon group, a C3-C20 aromatic A heterocyclic group is preferable, and an aromatic hydrocarbon ring group is particularly preferable.

  Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, iso-butyl group, sec-butyl group, tert-butyl group, hexyl group, octyl group and cyclohexyl group. Group, decyl group, octadecyl group and the like. Among these, Preferably, they are a methyl group, an ethyl group, and an isopropyl group, and a methyl group and an ethyl group are preferable from the point of being easy to obtain a raw material and cheap, and an iso-butyl group and a sec-butyl group. , Tert-butyl group is preferable because of its high solubility in nonpolar solvents.

  Examples of the aromatic hydrocarbon group having 6 to 25 carbon atoms include a naphthyl group such as a phenyl group, a 1-naphthyl group and a 2-naphthyl group, a phenanthyl group such as a 9-phenanthyl group and a 3-phenanthyl group, and 1-anthryl. Group, 2-anthryl group, anthryl group such as 9-anthryl group, 1-naphthacenyl group, naphthacenyl group such as 2-naphthacenyl group, 1-chrysenyl group, 2-chrysenyl group, 3-chrysenyl group, 4-chrysenyl group, 5-chrycenyl group, 6-chrycenyl group and other chrycenyl groups, 1-pyrenyl group and other pyrenyl groups, 1-triphenylenyl group and other triphenylenyl groups, 1-coronenyl group and other coronenyl groups, 4-biphenyl group and 3-biphenyl group In view of the stability of the compound, phenyl group, 2-naphthyl group, 1-ant Group, 9-phenanthryl group, 9-anthranyl group is preferably a phenyl group, 2-naphthyl group is particularly preferred from the purification ease of the compound.

  Examples of the aromatic heterocyclic group having 3 to 20 carbon atoms include thienyl group such as 2-thienyl group, furyl group such as 2-furyl group, imidazolyl group such as 2-imidazolyl group, and carbazolyl such as 9-carbazolyl group. Groups, pyridyl groups such as 2-pyridyl group, triazin-yl groups such as 1,3,5-triazin-2-yl group, and the like. Of these, a 9-carbazolyl group is preferable from the viewpoint of stability of the compound.

Examples of the alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, isopropyloxy group, cyclohexyloxy group, octadecyloxy group and the like. Of these, a methoxy group and an ethoxy group are preferable from the viewpoint of improving solubility in a solvent and the glass transition point of the compound, that is, heat resistance.
Examples of the (hetero) aryloxy group having 3 to 20 carbon atoms include a phenoxy group, a 2-naphthyloxy group, a 9-anthranyloxy group, and a 2-thienyloxy group. Among these, a phenoxy group and a 2-naphthyloxy group are preferable from the viewpoint of improving the solubility in a solvent.

Examples of the alkylthio group having 1 to 20 carbon atoms include methylthio group, ethylthio group, isopropylthio group, cyclohexylthio group and the like. Among these, a methylthio group and an ethylthio group are preferable from the viewpoint of improving solubility in a solvent and the glass transition point of the compound, that is, heat resistance.
Examples of the (hetero) arylthio group having 3 to 20 carbon atoms include a phenylthio group, a 1-naphthylthio group, a 9-anthranylthio group, and a 2-thienylthio group. Among these, a phenylthio group is preferable from the viewpoint of improving solubility in a solvent.

These groups may further have a substituent, and examples of the substituent include the same substituents as the above-mentioned Ar ¹ may have.
[About molecular weight]
The molecular weight of the organic compound represented by the formula (1) is usually 7000 or less, preferably 5,000 or less when considering the ease of purification of the compound, and particularly preferable when considering solubility in a solvent. Is preferably 3000 or less, and most preferably 1500 or less in view of high purity by sublimation purification. In general, the molecular weight of the organic compound represented by the formula (1) is 500 or more, and when considering the thermal stability of the compound, the molecular weight is preferably 600 or more.

[Solubility in solvents]
The organic compound represented by the formula (1) is preferably one that usually dissolves 0.5% by weight or more in toluene at room temperature (25 ° C.). It is preferable that it dissolves in an amount of not less than 0.0% by weight, and more preferable is that it dissolves in an amount of not less than 1.5% by weight because the film thickness of the coating film can be easily controlled. Those that dissolve at 0% by weight or more are particularly preferable, and those that dissolve at least 2.5% by weight are most preferable.

<About physical properties>
The organic compound represented by the formula (1) has a glass transition temperature (Tg) of preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and usually 180 ° C. or lower.
Within the above range, it is easy to control the arrangement of molecules in the film during wet film formation, performance fluctuation is reduced, thermal stability is improved, and driving as an element after film formation is performed. It is more preferable that the durability is good.

The electron mobility (μe) of the organic compound of the present invention is the method described in the section “Method for Measuring Electron Mobility” below, and μe is usually 2.0 × 10 ⁻⁷ cm ² / V · s or more. , Preferably 1.0 × 10 ⁻⁶ cm ² / V · s or more, more preferably 1.0 × 10 ⁻⁵ cm ² / V · s or more, and usually 1.0 × 10 ⁻¹ cm ² / V · s. s or less, preferably 1.0 × 10 ⁻² cm ² / V · s or less, more preferably 3.0 × 10 ⁻³ cm ² / V · s or less.
[Measurement Method of Charge Mobility] A measurement method by the TOF method will be described below.

(Preparation of charge mobility measurement sample)
As a sample for charge mobility measurement, a single element formed in the order of an anode, an organic layer, and a cathode is prepared on a substrate (hereinafter referred to as “measurement sample”). In addition, in order to measure, the anode and the cathode use one that transmits light. When measuring from the substrate side, a transparent substrate is also used for the substrate.

The organic layer is formed by a wet film formation method using a composition containing an organic compound and an organic solvent. The organic solvent used for preparing the composition is not particularly limited as long as it dissolves the organic compound well.
Although there is no restriction | limiting in particular in the wet film-forming method which forms an organic layer, For example, the casting method etc. are mentioned.

The film thickness of the organic layer is not particularly limited as long as it can be measured, but is set to 1 μm, for example.
(Measuring method)
The measurement method and principle are as follows.
In order to measure charge mobility, for example, Brio (lamp excitation Nd: YAG pulse laser, manufactured by Quantel) is used as a pulse light source, and a TDS2022 type oscilloscope (manufactured by Tektronix) is used as an oscilloscope.

In the measurement of charge mobility in the present invention, a voltage (0.3 to 0.5 MV / cm) is applied to a measurement sample prepared as described above at 25 ° C. In this state, pulse light is irradiated from the transparent electrode side of the measurement sample using, for example, Brio (lamp excitation Nd: YAG pulse laser, manufactured by Quantel).
At this time, the generated current is subjected to a current-voltage change by a shunt resistor, and a voltage waveform is observed using an oscilloscope.

Here, in order to further improve the measurement sensitivity, a voltage amplifier, for example, a DA1855A differential amplifier (manufactured by LeCroy) may be used.
Here, the time required for the charge to move from end to end in the organic layer, that is, between the electrodes, can be considered as the time from when the current is generated until the current disappears.
The time required for this charge to move in the organic layer is T (sec), and the voltage applied to the organic layer is V (V) (however, the voltage is 0.3 to 0.5 MV / cm. Assuming that the thickness of the organic layer is d (cm), the charge mobility is μ = d / [T × (V / d)] (cm ² / V · s)
Can be calculated.

By this method, for example, charge mobility is calculated at three or more voltages, and the Pool-Frenkel equation μ (E) = μ (0) × exp (β × E ^0.5 )
E = V / d
μ (0) = zero-field mobility
β: Poole-Frenkel factor
The charge mobility at an arbitrary electric field strength is calculated by fitting measured data by using the least square method.

By reversing the polarity of the voltage applied to the measurement sample, the polarity of the charge moving from the transparent electrode surface to the counter electrode is reversed, so that the hole mobility and the electron mobility are measured by the same method.
Note that the measuring instrument used for measuring the charge mobility is not limited to the above-described measuring instrument as long as the same measurement as described above is possible. It is preferable to use equipment.

<Specific example>
Although the preferable specific example of the organic compound of this invention is shown below, this invention is not limited to these.

<Synthesis Method of Organic Compound>
The organic compound of the present invention can be synthesized by selecting a raw material according to the structure of the target compound and using a known method.
For example, as shown in the figure below, by performing a combination of a boronic acid or a boronic acid ester and a halogen compound, a Suzuki coupling, a halogenation of an aromatic ring, and a reaction of converting a halogen moiety into a boronic acid or a boronic acid ester, Although the method etc. which produce | generate an aromatic-aromatic bond can be used preferably, it is not limited to this.

<Use of the organic compound of the present invention>
The organic compound of the present invention is preferably used as a light emitting material or a charge transport material (charge transporting compound), and is preferably used as a light emitting material or a charge transport material for a light emitting layer in an organic electroluminescent device. It is preferably used as a transport material.
Moreover, since the manufacturing method can be simplified, the organic compound of the present invention is preferably used for an organic layer formed by a wet film forming method.

In addition, the organic compound of this invention can be used suitably also for an electrophotographic photoreceptor, a photoelectric conversion element, an organic solar cell, an organic rectifying element, etc. besides an organic electroluminescent element.
<Composition for organic electroluminescence device>
The composition for organic electroluminescent elements of the present invention contains at least the organic compound of the present invention and a solvent.

The content of the organic compound of the present invention in the composition for organic electroluminescent elements is usually 0.5% by weight or more, preferably 1% by weight or more, usually 50% by weight or less, preferably 10% by weight or less. By setting it within this range, the effect of improving the light emission efficiency and lowering the voltage of the element can be obtained. In addition, the said organic compound may be contained only in 1 type in the composition, and may be contained in combination of 2 or more type.

The solvent contained in the composition is a volatile liquid component used for forming a layer containing the organic compound of the present invention by wet film formation.
The solvent is not particularly limited as long as the solute dissolves well, but the following examples are preferable.
For example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, and tetralin; halogenated fragrances such as chlorobenzene, dichlorobenzene, and trichlorobenzene Group hydrocarbons: 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethyl Aromatic ethers such as anisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; Alicyclic ketones such as Sanone, Cyclooctanone and Fencon; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Aliphatic alcohols such as butanol and hexanol; Ethylene And aliphatic ethers such as glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA).

Of these, alkanes and aromatic hydrocarbons are preferable. One of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.
In order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower.

  The amount of the solvent used is preferably 10% by weight or more, more preferably 50% by weight or more, particularly preferably 80% by weight or more, and preferably 99.95% with respect to 100% by weight of the composition for organic electroluminescent elements. % By weight or less, more preferably 99.9% by weight or less, particularly preferably 99.8% by weight or less. When the content is lower than the lower limit, the viscosity becomes too high, and the film forming workability may be lowered. On the other hand, if the value exceeds the upper limit, the film thickness obtained by removing the solvent after film formation cannot be obtained, so that film formation tends to be difficult.

In addition to the organic compound and the solvent of the present invention, the composition for an organic electroluminescent element of the present invention can contain a charge transporting compound used for an organic electroluminescent element, particularly a light emitting layer.
When forming a light emitting layer using the composition for organic electroluminescent elements of the present invention, the organic compound of the present invention may be used as a host material, and another charge transporting compound may be included as a dopant material, The organic compound of the present invention may be used as a dopant material, and another charge transporting compound may be included as a host material. Further, both the dopant material and the host material may be the organic compound of the present invention.

As other charge transporting compounds, those conventionally used as materials for organic electroluminescence devices can be used. For example, naphthalene, perylene, anthracene, pyrene, triphenylene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis (
2-phenylethenyl) benzene and derivatives thereof, quinacridone derivatives, DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) series compounds, benzopyran derivatives, rhodamine derivatives, benzothio Examples thereof include xanthene derivatives, azabenzothioxanthene, condensed aromatic ring compounds substituted with an arylamino group, and styryl derivatives substituted with an arylamino group.

The other charge transporting compound is usually 1% by weight or more, and usually 50% by weight or less, preferably 30% by weight or less, assuming that the composition is 100% by weight.
The composition for organic electroluminescent elements may further contain other compounds in addition to the above-described compounds as necessary. For example, in addition to the above solvent, another solvent may be contained. Examples of such a solvent include amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide. One of these may be used alone, or two or more may be used in any combination and ratio.

In addition, any other known material can be used as the other light emitting material, and a fluorescent light emitting material or a phosphorescent light emitting material can be used alone or in combination.
For the purpose of improving the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the light emitting material molecule or to introduce a lipophilic substituent such as an alkyl group.
Examples of fluorescent dyes that emit blue light include perylene, pyrene, anthracene, chrysene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

  Among these, derivatives of chrysene are preferable, and examples include the following specific examples.

Examples of the green fluorescent dye include quinacridone derivatives and coumarin derivatives.
Examples of yellow fluorescent dyes include rubrene and perimidone derivatives.
Examples of red fluorescent dyes include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene and the like.
Examples of the phosphorescent material include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table.

Preferred examples of the metal in the phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.
Moreover, you may contain various additives, such as a leveling agent and an antifoamer, for the purpose of the improvement of film formability.

<Organic electroluminescent device>
The organic electroluminescent element of the present invention has at least an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate, and is wet-film-formed using the composition for organic electroluminescent elements of the present invention. It has the layer formed by the method. The layer formed by the wet film formation method is preferably the light emitting layer.

FIG. 1 is a schematic cross-sectional view showing a structure example suitable for the organic electroluminescent device of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a light emitting layer, Each of the electron injection layers 6 represents a cathode.
[Organic electroluminescence device]
The organic electroluminescent element of the present invention has at least an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate, and is wet-film-formed using the composition for organic electroluminescent elements of the present invention. It has the layer formed by the method. The layer formed by the wet film formation method is preferably the light emitting layer.

FIG. 1 is a schematic cross-sectional view showing a structure example suitable for the organic electroluminescent device of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a light emitting layer, Each of the electron injection layers 6 represents a cathode.
[1] Substrate
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

[2] Anode
An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (such as the hole injection layer 3 or the light emitting layer 4).
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or A conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline is used.

  In general, the anode 2 is often formed by sputtering, vacuum deposition, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing and coating the substrate 1. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.
(Hole injection layer)
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.

The method for forming the hole injection layer 3 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When forming the hole injection layer 3 by wet film formation, the material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (hole injection layer solvent) to form a film-forming composition (positive A composition for forming a hole injection layer), and applying the composition for forming a hole injection layer on a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate technique. The hole injection layer 3 is formed by coating and drying.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer.
The hole transporting compound is a compound having a hole transporting property that is usually used in a hole injection layer of an organic electroluminescence device, and may be a polymer compound or the like, a monomer or the like. Although it may be a low molecular weight compound, it is preferably a high molecular weight compound.

  The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.
The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. It is preferable to use the above in combination.
Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

  The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In the formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{3 to} Ar ⁵ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Represents a linking group selected from the group of linking groups, and among Ar ^{1 to} Ar ⁵ , two groups bonded to the same N atom may be bonded to each other to form a ring.

(In the above formulas, Ar ^{6 to} Ar ¹⁶ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an arbitrary substituent.))
As the aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.
When R ¹ and R ² are optional substituents, examples of the substituent include alkyl groups, alkenyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, and the like. .

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.
In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), a polythiophene derivative, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, the end of this polymer may be capped with methacrylate or the like.

Furthermore, as the hole transporting compound, a crosslinkable compound described in the section of [Hole transporting layer] described later may be used. When a crosslinkable compound is used, the film forming method is the same.
The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(Electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron accepting compound as a constituent material of the hole injection layer.
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.

Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

These electron accepting compounds can improve the conductivity of the hole injection layer by oxidizing the hole transporting compound.
The content of the electron-accepting compound in the hole-injecting layer or the composition for forming a hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(Other components)
As a material for the hole injection layer, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly 200 ° C. or higher, usually 400 ° C. or lower, and preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying step, which may adversely affect other layers and the substrate.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.
Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide, and the like.

In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.
(Film formation method)
After preparing the composition for forming the hole injection layer, the composition is applied on the layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by wet film formation, and dried. The hole injection layer 3 is formed.

The temperature in the coating step is preferably 10 ° C. or higher and preferably 50 ° C. or lower in order to prevent film loss due to the formation of crystals in the composition.
Although the relative humidity in an application | coating process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally, and usually 80% or less.
After coating, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

  In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.

<Formation of hole injection layer by vacuum deposition>
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum vessel. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and control the evaporation amount to evaporate (when using two or more materials, control each evaporation amount independently) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate placed on the substrate. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but usually 0.1 × 10 ⁻⁶ Torr (0.13 × 10 ⁻⁴ Pa) or more, usually 9.0 × 10 ⁻⁶ Torr. (12.0 × 10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

[Hole transport layer]
The method for forming the hole transport layer 4 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole transport layer 4 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The hole transport layer 4 can be formed on the hole injection layer 3 when there is a hole injection layer and on the anode 2 when there is no hole injection layer 3. The organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.

  The material for forming the hole transport layer 4 is preferably a material having high hole transportability and capable of efficiently transporting injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, it is preferable not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency because it is in contact with the light emitting layer 5.

Such a material for the hole transport layer 4 may be any material conventionally used as a constituent material for the hole transport layer. For example, the hole transport property used for the hole injection layer 3 described above What was illustrated as a compound is mentioned. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives,
Examples include porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes, and the like.

  In addition, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.

Of these, polyarylamine derivatives and polyarylene derivatives are preferred.
The polyarylamine derivative is preferably a polymer containing a repeating unit represented by the following formula (II). In particular, the polymer is preferably composed of a repeating unit represented by the following formula (II). In this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)
Examples of the aromatic hydrocarbon group which may have a substituent include, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, and acenaphthene. Examples include a group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a fluoranthene ring, a fluorene ring, and a group in which these rings are linked by a direct bond.

  Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine Ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. ring Are those groups group and the rings of from 2-4 fused ring is linked by a direct bond or two or more rings.

Ar ^a and Ar ^b are each independently a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring, a fluorene from the viewpoint of solubility and heat resistance in an organic solvent. A group derived from a ring selected from the group consisting of rings or a group formed by linking two or more benzene rings (for example, a biphenyl group (biphenylene group) or a terphenyl group (terphenylene group)) is preferable.

Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.
Examples of the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group in Ar ^a and Ar ^b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and a dialkyl. Examples thereof include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent exemplified as Ar ^a or Ar ^b in the formula (II) is used as ^a repeating unit. The polymer which has is mentioned.
As a polyarylene derivative, the polymer which has a repeating unit which consists of following formula (III-1) and / or following formula (III-2) is preferable.

(In formula (III-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, they are contained in one molecule. A plurality of R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In formula (III-2), R ^e and R ^f are each independently the same as R ^a , R ^b , R ^c or R ^d in formula (III-1). Independently represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or R ^f may form a ring, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)
Specific examples of X are —O—, —BR—, —NR—, —SiR ₂ —, —PR—, —SR—, —CR ₂ —, or a group formed by bonding thereof. R represents a hydrogen atom or an arbitrary organic group. The organic group in the present invention is a group containing at least one carbon atom.

  The polyarylene derivative has a repeating unit represented by the following formula (III-3) in addition to the repeating unit consisting of the formula (III-1) and / or the formula (III-2). Is preferred.

(In formula (III-3), Ar ^{c to} Ar ^j each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, and v and w each represent Independently represents 0 or 1.)
Specific examples of Ar ^{c to} Ar ^j are the same as Ar ^a and Ar ^b in the formula (II).
Specific examples of the above formulas (III-1) to (III-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.

In the case of forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer 3 and then heated and dried after the wet film formation. .
The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the composition for forming a hole injection layer. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

In the case where the hole transport layer is formed by the vacuum deposition method, the film forming conditions are the same as those in the case of forming the hole injection layer 3.
The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.
The hole transport layer 4 may also be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.
The crosslinkable compound may be any of a monomer, an oligomer, and a polymer. The crosslinkable compound may have only 1 type, and may have 2 or more types by arbitrary combinations and ratios.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include those exemplified above, and those having a crosslinkable group bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) and formulas (III-1) to (III-3) can be used as a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of hole transporting compounds include pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives,
Nitrogen-containing aromatic compound derivatives such as phthalocyanine derivatives and porphyrin derivatives; triphenylamine derivatives; silole derivatives; oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes, and the like. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives.

In order to form a hole transport layer 4 by crosslinking a crosslinkable compound, a composition for forming a hole transport layer in which a crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.
The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that promote the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, And photosensitizers such as porphyrin compounds and diaryl ketone compounds.

Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin;
In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20%. It is contained in an amount of not more than wt%, more preferably not more than 10 wt%.

After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinked by heating and / or irradiation with active energy such as light. Are crosslinked to form a network polymer compound.
Conditions such as temperature and humidity during film formation are the same as those during the wet film formation of the hole injection layer 3.
The heating method after film formation is not particularly limited. As heating temperature conditions, it is 120 degreeC or more normally, Preferably it is 400 degrees C or less.

The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a coated film layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.
In the case of irradiation with active energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, or the above-mentioned light source is incorporated. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In active energy irradiation other than light, for example, there is a method of irradiation using a so-called microwave oven that irradiates a microwave generated by a magnetron. As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

The irradiation of active energy such as heating and light may be performed alone or in combination. When combined, the order of implementation is not particularly limited.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.
[4] Light emitting layer
A light emitting layer 4 is usually provided on the hole injection layer 3. The light emitting layer 4 is, for example, a layer containing the above-described light emitting material. Between the electrodes to which an electric field is applied, holes injected from the anode 2 through the hole injection layer 3 and from the cathode 6 through the electron transport layer 5 are injected. It is a layer that is excited by recombination with other electrons and becomes the main light emitting source. The light-emitting layer 4 preferably contains a light-emitting material (dopant) and one or more host materials, and the light-emitting layer 4 more preferably contains the organic compound of the present invention as a host material, and is formed by a vacuum evaporation method. However, it is particularly preferable that the layer be prepared by a wet film-forming method using the composition for organic electroluminescent elements of the present invention.

Here, the wet film forming method is, as described above, a composition containing a solvent, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating. This method is a wet film formation method such as a method, an ink jet method, a screen printing method, a gravure printing method, or a flexographic printing method.
In addition, the light emitting layer 4 may contain other materials and components as long as the performance of the present invention is not impaired.

  In general, when the same material is used in the organic electroluminescent element, the thinner the film thickness between the electrodes, the larger the effective electric field, so that the injected current increases, so the driving voltage decreases. For this reason, the driving voltage of the organic electroluminescence device decreases when the total film thickness between the electrodes is thin, but if it is too thin, a short circuit occurs due to the protrusion caused by the electrode such as ITO. Necessary.

  In the present invention, in addition to the light emitting layer 4, when the organic layer such as the hole injection layer 3 and the electron transport layer 5 described later is provided, the light emitting layer 4 and other organic materials such as the hole injection layer 3 and the electron transport layer 5 are used. The total film thickness combined with the layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 4 and the electron injection layer 5 described later is high, the amount of charge injected into the light emitting layer 4 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 4 and maintaining the total thickness to some extent.

Therefore, the thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present invention has only the light emitting layer 4 between the anode and the cathode, the thickness of the light emitting layer 4 is usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm or less. is there.
[5] Electron injection layer
The electron injection layer 5 serves to efficiently inject electrons injected from the cathode 6 into the light emitting layer 4. In order to perform electron injection efficiently, the material for forming the electron injection layer 5 is preferably a metal having a low work function, and alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium are used.

The film thickness of the electron injection layer 5 is preferably 0.1 to 5 nm.
Also, an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ may be inserted at the interface between the cathode 6 and the light emitting layer 4 or the electron transport layer 8 described later. This is an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; JP-A-10-74).
586 publication; IEEE Trans. Electron. Devices, 44, 1245, 1997; SID 04 Digest, 154).

  Furthermore, organic metal transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in JP-A-10-270171, JP-A 2002-1000047, JP-A 2002-1000048, and the like) makes it possible to improve electron injection / transport properties and achieve excellent film quality. Therefore, it is preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 5 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum deposition method in the same manner as the light emitting layer 4. In the case of the vacuum vapor deposition method, the vapor deposition source is put in a crucible or metal boat installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with an appropriate vacuum pump, and then the crucible or metal boat is Evaporate by heating to form an electron injection layer on the substrate placed facing the crucible or metal boat.

The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are simultaneously heated and evaporated to form an electron injection layer on the substrate placed facing the crucible and dispenser.

At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 5, but there may be a concentration distribution in the film thickness direction.
The electron injection layer 5 may be omitted as shown in FIGS.
[6] Cathode
The cathode 6 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 5 or the light emitting layer 4). The material used for the cathode 6 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, such as tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

The film thickness of the cathode 6 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.
[7] Other constituent layers
As described above, the element having the layer structure shown in FIG. 1 has been mainly described. However, the above description is provided as long as the performance is not impaired between the anode 2 and the cathode 6 and the light emitting layer 4 in the organic electroluminescent element of the present invention. In addition to the layers, any layer may be included, and any layer other than the light emitting layer 4 may be omitted.

Examples of the layer that may be included include the electron transport layer 7. The electron transport layer 7 is provided between the light emitting layer 4 and the electron injection layer 5 as shown in FIG. 2 for the purpose of further improving the light emission efficiency of the device.
The electron transport layer 7 is formed of a compound capable of efficiently transporting electrons injected from the cathode 6 between electrodes to which an electric field is applied in the direction of the light emitting layer 4. As the electron transporting compound used for the electron transport layer 7, the electron injection efficiency from the cathode 6 or the electron injection layer 5 is high, and the injected electrons can be efficiently transported with high electron mobility. It must be a compound.

Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, Styryl biphenyl derivatives, silole derivatives, 3- or 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948)
No.), quinoxaline compounds (JP-A-6-207169), phenanthroline derivatives (JP-A-5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogen Amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like.

The lower limit of the thickness of the electron transport layer 7 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm.
The electron transport layer 7 is formed by laminating on the light emitting layer 4 by the wet film formation method or the vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.
In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting substance, it is also effective to provide the hole blocking layer 8 as shown in FIG. The hole blocking layer 8 has a function of confining holes and electrons in the light emitting layer 4 and improving luminous efficiency. That is, the hole blocking layer 8 is generated by blocking the holes moving from the light emitting layer 4 from reaching the electron transport layer 7, thereby increasing the recombination probability with electrons in the light emitting layer 4. There is a role of confining excitons in the light emitting layer 4 and a role of efficiently transporting electrons injected from the electron transport layer 8 toward the light emitting layer 4.

The hole blocking layer 8 prevents the holes moving from the anode 2 from reaching the cathode 6 and can efficiently transport the electrons injected from the cathode 6 toward the light emitting layer 4. The compound is laminated on the light emitting layer 4 so as to be in contact with the interface of the light emitting layer 4 on the cathode 6 side.
The physical properties required for the material constituting the hole blocking layer 8 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the hole blocking layer material satisfying such conditions include mixed arrangements of bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryl compounds such as distyrylbiphenyl derivatives ( JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7-41759) And phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297).

Furthermore, compounds having at least one pyridine ring substituted at the 2,4,6-positions described in International Publication No. 2005/022962 are also preferable as the hole blocking material.
The film thickness of the hole blocking layer 8 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.
The hole blocking layer 8 can also be formed by the same method as the hole injection layer 3, but a vacuum deposition method is usually used.

The electron transport layer 7 and the hole blocking layer 8 may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole blocking layer, 3) Stack of hole blocking layer / electron transport layer, 4) There are usages such as not using.
For the same purpose as the hole blocking layer 8, it is also effective to provide an electron blocking layer 9 between the hole injection layer 3 and the light emitting layer 4 as shown in FIG. The electron blocking layer 9 increases the probability of recombination with holes in the light emitting layer 4 by blocking the electrons moving from the light emitting layer 4 from reaching the hole injection layer 3, thereby generating excitons generated. Has a role of confining the light in the light emitting layer 4 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 4.

The characteristics required for the electron blocking layer 9 are high hole transportability, energy gap (H
The difference between OMO and LUMO is large, and the excited triplet level (T1) is high. Further, when the light emitting layer 4 is formed by a wet film forming method, it is preferable that the electron blocking layer 9 is also formed by a wet film forming method because the device manufacturing becomes easy.
For this reason, it is preferable that the electron blocking layer 9 also has wet film forming compatibility, and examples of the material used for such an electron blocking layer 9 include dioctylfluorene represented by F8-TFB in addition to the organic compound of the present invention. And a copolymer of triphenylamine (WO 2004/084260 pamphlet) and the like.

The structure opposite to that shown in FIG. 1, that is, the cathode 6, the electron injection layer 5, the light emitting layer 4, the hole injection layer 3, and the anode 2 can be laminated on the substrate 1 in this order. It is also possible to provide the organic electroluminescent element of the present invention between two substrates, at least one of which is highly transparent. Similarly, it is also possible to laminate | stack to the structure opposite to the said each layer structure shown in FIGS.
Further, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of luminous efficiency and driving voltage.

The present invention can be applied to any of an organic electroluminescent element having a single element, an element having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix.
<Organic EL display device>
The organic EL display device of the present invention uses the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the model and structure of the organic electroluminescent display apparatus of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.

For example, the organic EL display device of the present invention can be obtained by the method described in “Organic EL display” (Ohm, published on Aug. 20, 2004, Shizushi Tokito, Chiba Adachi, Hideyuki Murata). Can be formed.
<Organic EL lighting>
The organic EL illumination of the present invention uses the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the model and structure of the organic EL illumination of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.

<Example>
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be arbitrarily modified and implemented without departing from the gist thereof.
[Synthesis Example of Compound H-1]
(Synthesis of Compound 2)

3-bromo-iodobenzene (25 g, 88 mmol) and 1-naphthylboronic acid (
13.8 g, 80 mmol) was dissolved in a mixed solvent of 240 ml of toluene / 120 ml of ethanol, 1 g of tetrakis (triphenylphosphine) palladium and 125 ml of 2M sodium carbonate aqueous solution were added, and the reaction was carried out under a nitrogen stream for 4 hours with stirring under reflux. Toluene and water were added, and the mixture was separated and purified by silica gel column chromatography. This operation was performed twice to obtain 37 g of Compound 2 in total.

  (Synthesis of Compound 3)

1-Bromo-3-naphthylbenzene (20 g, 71 mmol) was dissolved in 250 ml dehydrated THF. The solution was kept at −78 ° C. and 50 ml of 1.2 MR n-BuLi in hexane was added. After stirring for 1 hour, 25 ml of trimethyl borate was added, and after stirring for 2 hours, the temperature was gradually raised. 1N-HCl was added, and 50 ml of methylene chloride was added for extraction, followed by concentration and drying. This operation was repeated twice to obtain 37 g of Compound 3.

  (Synthesis of Compound 4)

3-Bromo-iodobenzene (17.6 g, 62 mmol) and naphthylphenylboronic acid 3 (14.0 g, 62.1 mmol) were dissolved in a mixed solvent of 170 ml of toluene / 85 ml of ethanol, 85 ml of 2M aqueous sodium carbonate solution, tetrakis (triphenyl) Phosphine) palladium (2 g) was added, and the mixture was allowed to react with stirring under reflux for 6 hours under a nitrogen stream. Toluene and water were added, and the mixture was separated and purified by silica gel column chromatography to obtain 13.0 g of compound 4.

  (Synthesis of Compound 5)

3′-Bromophenyl-3- (1-naphthyl) benzene 4 (13.0 g, 36 mmol) was dissolved in 200 ml of dehydrated THF. The solution was kept at −78 ° C. and 24 ml of 1.05 MR n-BuLi in hexane was added. After stirring for 1 hour, 12 ml of trimethyl borate was added, and after stirring for 2.5 hours, the temperature was gradually raised. Add 200 ml of 1N-HCl,
Extracted with 400 ml of ethyl acetate, concentrated to dryness, washed with hexane to obtain 13.6 g of compound 5.

  (Compound 6)

Naphtylbiphenylboronic acid 5 (5.34 g, 16.5 mmol) and 9-bromoanthracene (4.03 g, 15.7 mmol) are dissolved in a mixed solvent of 100 ml of toluene / 50 ml of ethanol, 40 ml of 2M aqueous sodium carbonate solution is added, and tetrakis ( 0.9 g of triphenylphosphine) palladium was added, and the reaction was allowed to stir at 80 ° C. for 6.5 hours under a nitrogen stream. Toluene and water were added, and the mixture was separated and purified by silica gel column chromatography to obtain 4.1 g of compound 6.

  (Synthesis of Compound 7)

Naphthylbiphenylanthracene 6 (4.11 g, 9 mmol) was added to 20 ml of N, N-dimethylformamide at room temperature and stirred, and N-bromosuccinimide (1.6 g, 9 m) was stirred.
mol) in DMF (20 ml) was added, and the mixture was further stirred for 2 hr. Water and methanol were added to obtain 4.66 g of crystals by filtration. The product was used in the next reaction without further purification.

  (Synthesis of Compound H-1)

Compound 7 (2.64 g, 4.9 mmol) and dibenzofuranboronic acid (1.46 g, 6.9 mmol) were dissolved in a mixed solvent of toluene (50 ml) / ethanol (25 ml), 25 mL of 2M aqueous sodium carbonate solution was added, and tetrakis ( Triphenylphosphine)
Palladium (0.11 g) was added, and the reaction was allowed to stir at 80 ° C. for 3.5 hours under a nitrogen stream. Toluene and water were added, and the mixture was separated, purified by silica gel column chromatography, and then purified by sublimation to obtain 2.31 g of H-1.
The compound H-1 was confirmed by DEI-MS (m / z = 622 (M +)).

[Synthesis Example of Compound H-2]
(Synthesis of Compound 8)

Under nitrogen flow, 9-Broomoanthracene, (5.0 g, 19.45 mmol), Compound 3 (6.76 g, 27.24 mmol), Toluene / EtOH, 70 ml / 35 ml, NaCO ₃ (2M) 30 ml were stirred at 65 ° C. for 1 h, and Pd ( PPh3) 4 (1.32 g, 1.16 mmol) was added and refluxed for 6 hours. Liquid separation was performed twice with Toluene. Filter and concentrate with organic layer activated clay + MgSO4. Purification by column chromatography gave Compound 8 (7.0 g).
(Synthesis of Compound 9)

At room temperature, naphthylphenylanthracene 8 (7.5 g, 19.71 mmol) is added to 140 ml of DMF, and NBS, (3.51 g, 19.71 mmol) is dissolved in 20 ml DMF while stirring and added dropwise. After stirring for 1 hour, MeOH and water are mixed. Reprecipitate in solvent. Wash with MeOH and filter. 7.1 g of light yellow solid compound 9 was obtained.
(Synthesis of Compound H-2)

Under nitrogen stream, compound 9 (4.64g, 10.11mmol), 4- (Dibenzofuranyl) boronic acid, (3.0g, 14.15mmol), Toluene / EtOH, 80ml / 40ml, Na2CO3 (2M) 30ml is stirred at 65 ℃ for 1h. , Pd (PPh3) 4, 0.58 g (0.506 mmol) was added and refluxed for 4.5 hours. After liquid separation twice with Toluene, it was concentrated and purified by column chromatography (n-Hexane: Toluene = 5: 1) to obtain 2.5 g of pale yellow solid compound H-2. The compound H-2 was confirmed by DEI-MS (m / z = 546 (M +)).

[Synthesis Example of Compound H-3]
(Synthesis of Compound 10)

Under a nitrogen stream, 65 mg of 7-hydroxy-1-iodonaphthalene (6.62 g, 26.7 mmol), compound 3 (9.28 g, 37.38 mmol), Toluene / EtOH, 100 ml / 50 ml, NaCO ₃ (2M) 42 ml The mixture was stirred at ° C. for 1 h, Pd (PPh ₃ ) ₄ (1.85 g, 1.624 mmol) was added, and the mixture was refluxed for 6 hr. Liquid separation was performed twice with Toluene. Filter and concentrate with organic layer activated clay + MgSO ₄ . Purification by column chromatography gave 6.1 g of compound 10.

  (Synthesis of Compound 11)

Under a nitrogen stream, compound 10 (6.1 g, 17.6 mmol), dichloromethane (15 ml) and triethylamine (3.56 g) were added to a 200 ml flask, and trifluoromethanesulfonic anhydride (5.96 g) was cooled in an ice-water bath. 21.1 mmol) was added.
After the entire amount was added, the mixture was returned to room temperature and stirred for 5 hours. Water and 1N hydrochloric acid were added, extracted with dichloromethane, washed with dilute hydrochloric acid, dried over MgSO ₄ , concentrated, and purified by column chromatography to obtain 6.69 g of compound 11.

  (Synthesis of Compound 12)

Under a nitrogen stream, 4-dibenzofuranboronic acid (4.99 g, 23.5 mmol), 9-bromoanthracene (6.96 g, 27.1 mmol), Toluene / EtOH, 140 ml / 70 ml, NaCO ₃ (2M) 35 ml, Pd ( PPh ₃ ) ₄ (1.27 g, 1.1 mmol) was added and refluxed for 6 hours. Liquid separation was performed twice with Toluene. Filter with MgSO4 and concentrate. 6. Purify by column chromatography to obtain compound 12.
23 g was obtained.

  (Synthesis of Compound 13)

N-Bromo Amber dissolved in 20 ml of DMF while stirring a mixture of Compound 12 (7.23 g, 21.0 mmol) with N, N-dimethylformamide (DMF, 100 ml) in an ice-water bath under a nitrogen stream. Acid imide (3.78 g, 21.2 mmol) was added dropwise over 30 minutes. Thereafter, the ice-water bath was removed, DMF (55 ml) was added, and the mixture was stirred at room temperature for 6 hours. Water (about 100 ml) and dichloromethane (about 200 ml) were added for liquid separation. Filter with MgSO ₄ and concentrate. Washing with methanol (100 ml) gave 8.09 g of compound 13.

  (Synthesis of Compound 14)

Under a nitrogen stream, 12 (8.0 g, 18.9 mmol) was dehydrated in tetrahydrofuran (300 ml).
And was immersed in a dry ice / ethanol bath to adjust the internal temperature to −60 ° C. or lower. Thereafter, a normal butyl lithium / hexane solution (1.65 mol / l, 15 ml) was added dropwise over 30 minutes. Then, after stirring at −60 ° C. or lower for 2 hours, triisopropyl borate (4.07 g, 21.6 mmol) was added dropwise over 10 minutes, and then stirred for 20 minutes. The dry ice ethanol bath was removed and the mixture was further stirred for 30 minutes. Thereafter, 1N-HCl (50 ml) was added, and water (about 100 ml) and ethyl acetate (about 200 ml) were added for liquid separation. Filter with MgSO4 and concentrate. After dissolving in dichloromethane, methanol was added for reprecipitation, and the mixture was washed repeatedly with hot hexane. 3.77 g of compound 14 was obtained.

  (Synthesis of Compound H-3)

Under nitrogen flow, Compound 14 (3.54 g, 9.12 mmol), Compound 11 (3.61 g, 7.55 mmol), Toluene / EtOH, 38 ml / 19 ml, NaCO ₃ (2M) 12 ml, Pd (PPh ₃ ) ₄ ( 0.432g
0.374 mmol) was added and refluxed for 3 hours. Liquid separation was performed twice with Toluene. The organic layer was treated with MgSO4, filtered and concentrated. Purification by column chromatography gave 3.9 g of compound H-3.

The compound H-3 was confirmed by DEI-MS (m / z = 672 (M +)).
<Measurement of physical properties of organic compounds>
[Measurement of glass transition temperature]
Product names of Compounds H-1 to H-3 synthesized in [Synthesis Example of Compound H-1] to [Synthesis Example of Compound H-3] and Comparative Compounds J-1 to J-3 shown below : Glass transition temperature was measured using DSC 6220, manufactured by SII Nanotechnology. The results are summarized in Table 1.

[Measurement of solubility in toluene]
[Synthesis Example of Compound H-1] to [Synthesis Example of Compound H-3] Compounds H-1 to H synthesized in [Synthesis Example of Compound H-3]
-3 and Comparative Compounds (J-1) to (J-3) were measured for solubility in toluene at room temperature (25 ° C.). The results are summarized in Table 1.
[Measurement of electron mobility]
<Creation of measurement sample>
On a glass substrate 1, an indium tin oxide (ITO) transparent conductive film deposited to a thickness of 150 nm (manufactured by Sanyo Vacuum Co., Ltd., sputtered film) is subjected to normal photolithography technology and hydrochloric acid etching. Then, an ITO layer was formed as an anode 2 by patterning into a stripe having a width of 2 mm to obtain an ITO substrate.

The ITO substrate was cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, and then dried with compressed air.
Next, the material of the present invention is dissolved in toluene to prepare a coating solution, and this is applied on the anode 2 under the conditions of spinner rotation speed: 1500 rpm, spinner rotation time: 30 seconds, spin coating atmosphere: in nitrogen. A sample layer was formed by spin coating and baking. In addition, 0.03-0.04 weight% of surface smoothing agent was added to each coating liquid with respect to toluene. As the surface smoothing agent, KF-96-10cs (manufactured by Shin-Etsu Silicone) was used.

The element on which the sample layer was formed was placed in the vacuum deposition layer. At that time, a stripe shadow mask having a width of 2 mm, which is a mask for cathode vapor deposition, was brought into close contact with the element so as to be orthogonal to the ITO stripe of the anode 2. The inside of the apparatus was evacuated roughly by a scroll pump and then evacuated by a turbo molecular pump until the degree of vacuum in the apparatus was 9.9 × 10 ⁻⁴ Pa or less.

Thereafter, aluminum is heated by a molybdenum boat, and an aluminum layer having a film thickness of 40 to 80 nm is formed on the cathode 9 by controlling the deposition rate from 0.6 to 16.0 Å / sec and the degree of vacuum from 2.0 to 25 × 10 ⁻⁴ Pa. Formed as. In addition, the substrate temperature at the time of vapor deposition of the above aluminum layer was kept at room temperature.
Subsequently, in order to prevent the measuring element from being deteriorated by moisture in the atmosphere during storage, a sealing treatment was performed by the method described below. In a nitrogen glove box connected to a vacuum deposition apparatus, a photocurable resin 30Y-437 (manufactured by ThreeBond Co., Ltd.) with a width of about 1 mm is applied to the outer periphery of a 23 mm × 23 mm glass plate, and moisture is applied to the center. A getter sheet (manufactured by Dynic) was installed. On top of this, the measuring element was bonded so that the surface on which the cathode 9 was deposited was opposed to the desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened. As described above, a measuring element having an element area of 2 mm × 2 mm was produced.

  As a method for measuring the charge mobility, the time of flight measurement method (ToF method) was used. Electric field strength E (V / cm) was applied so that the cathode 2 side of the measuring element was at a high potential. Next, the anode 2 on the measuring element surface was irradiated with light having a wavelength of 355 nm, which is the third harmonic, for a short time using an Nd: YAG nanosecond pulse laser. The transient photocurrent generated at that time was detected, and the inflection point was defined as the flight time ttr (s). From the flight time ttr and the electric field strength E (= V / d, V: potential difference between the anode 2 and the cathode 9 of the measuring element, d: film thickness of the sample layer 10 of the measuring element), the following equation is used. Thus, the electron mobility μe was calculated. Values are shown in the table at an electric field strength of 0.4 MV / cm.

    μe = d / [T × (V / d)] (cm2 / V · s)

Example 4
[Creation of organic electroluminescence device]
An organic electroluminescent element having the structure shown in FIG. 1 was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 having a thickness of 150 nm (sputtered film; sheet resistance 15 Ω) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching. Thus, an anode 2 was formed. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

  Next, the hole injection layer 3 was formed by a wet film formation method as follows. As a material for the hole injection layer 3, a polymer compound having an aromatic amino group of the following formula (PB-1) (weight average molecular weight: 52000, number average molecular weight: 32500) and an electron accepting property of the following structural formula Using the compound (A-2), spin coating was performed under the following conditions.

<Composition for hole injection layer>
Solvent ethyl benzoate
Coating solution concentration PB-1 2.0% by weight
A-2 0.4% by weight
<Film formation conditions>
Spinner speed 2250rpm
Spinner rotation time 30 seconds
Spin coat atmosphere Atmosphere 25 ℃
Drying conditions 230 ° C x 60 minutes
A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

  Subsequently, a hole transport layer was formed by a wet film forming method as follows. A composition for organic electroluminescence device was prepared using a charge transport material (PB-2) having the following structural formula as a material for the hole transport layer and cyclohexylbenzene as a solvent, and the composition for organic electroluminescence device Was used for spin coating under the following conditions.

<Composition for hole transport layer>
Solvent Cyclohexylbenzene
Coating solution concentration PB-2 1.4% by weight
<Film formation conditions>
Spinner speed 1500rpm
Spinner rotation time 120 seconds
Spin coat atmosphere 25 ° C in dry nitrogen
Drying conditions 230 ° C x 60 minutes (under dry nitrogen)
A uniform thin film having a thickness of 20 nm was formed by the above spin coating.

Next, in forming the light emitting layer, the organic compound (H-1) of the present invention shown in Synthesis Example 1 is used as the charge transport material, and the organic compound (D-1) having the following structure is used as the light emitting material. The organic electroluminescent element composition shown below was prepared and spin-coated on the hole transport layer under the following conditions to obtain a light emitting layer with a film thickness of 45 nm.
<Composition for light emitting layer>
Solvent Cyclohexylbenzene
Concentration in composition H-1: 5% by weight
D-1: 0.35% by weight
<Spin coating conditions>
Spinner speed 2000rpm
Spinner rotation time 120 seconds
Drying conditions 130 ° C x 60 minutes (under reduced pressure)
A uniform thin film having a thickness of 50 nm was formed by the above spin coating.

Next, a pyridine derivative (HB-1) shown below was laminated as a hole blocking layer at a crucible temperature of 251 to 252 ° C. with a deposition rate of 0.08 to 0.12 nm / second and a thickness of 10 nm. The degree of vacuum during the deposition was 2.1 to 2.4 × 10 ⁻⁴ Pa (about 1.6 to 1.8 × 10 ⁻⁶ Torr).

Next, an aluminum 8-hydroxyquinoline complex (ET-1) shown below was deposited as an electron transport layer on the hole blocking layer in the same manner. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex is controlled in the range of 222 to 239 ° C., and the degree of vacuum during the deposition is 1.7 to 2.0 × 10 ⁻⁴ Pa (about 1.3 to 1. 5 × 10 ⁻⁶ Torr), the deposition rate was 0.1 nm / second, and the film thickness was 30 nm.

The substrate temperature during vacuum deposition of the hole blocking layer and the electron transport layer was kept at room temperature.
Here, the element on which the electron transport layer has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide stripe shadow mask is orthogonal to the ITO stripe of the anode 2 as a mask for cathode deposition. In close contact with the element, it is placed in another vacuum deposition apparatus and the degree of vacuum in the apparatus is 2.3 × 10 ⁻⁶ Torr (about 3.0 × 10 ⁻⁴ Pa) in the same manner as the organic layer. Exhaust until below.

Next, lithium fluoride (LiF) is deposited on the electron transport layer as an electron injection layer by using a molybdenum boat, a deposition rate of 0.015 nm / second, and a degree of vacuum of 2.5 × 10 ⁻⁶ Torr (about 3 3 × 10 ⁻⁴ Pa) and a film thickness of 0.5 nm was formed on the electron transport layer.
Next, on the electron injection layer, aluminum is heated as a cathode by a molybdenum boat, a deposition rate of 0.5 to 3.0 nm / second, and a degree of vacuum of 3.3 to 7.5 × 10 ⁻⁶ Torr (about The film was formed at 4.4 to 10.0 × 10 ⁻⁴ Pa) to form an aluminum layer having a thickness of 80 nm, thereby completing the cathode.

The substrate temperature at the time of vapor deposition of the electron injection layer and the cathode was kept at room temperature.
As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this element are as follows.
Luminance / current: 4.6 [cd / A] (@ 100 cd / m ² )
Voltage: 6.0 [V] (@ 100 cd / m ² )
Luminous efficiency: 2.4 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 464 nm, and the chromaticity was CIE (x, y) = (0.14, 0.16).
(Example 5) An element was prepared in the same manner as in Example 4 except that H-2 was used instead of H-1.
Luminance / current: 4.7 [cd / A] (@ 100 cd / m ² )
Voltage: 5.7 [V] (@ 100 cd / m ² )
Luminous efficiency: 2.6 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 465 nm, and the chromaticity was CIE (x, y) = (0.14, 0.18).
(Example 6) An element was prepared in the same manner as in Example 4 except that H-3 was used instead of H-1.
Luminance / current: 4.4 [cd / A] (@ 100 cd / m ² )
Voltage: 5.7 [V] (@ 100 cd / m ² )
Luminous efficiency: 2.4 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 464 nm, and the chromaticity was CIE (x, y) = (0.14, 0.15).
Comparative Example 4 A device was prepared in the same manner as in Example 4 except that Comparative Compound J-1 was used instead of H-1.
Luminance / current: 4.3 [cd / A] (@ 100 cd / m ² )
Voltage: 6.0 [V] (@ 100 cd / m ² )
Luminous efficiency: 2.2 [1 m / W] (@ 100 cd / m ² )
The maximum wavelength of the emission spectrum of the device was 464 nm, and the chromaticity was CIE (x, y) = (0.14, 0.15).

  As shown in Table 2, the organic electroluminescent device produced using the organic compound of the present invention has high current efficiency and luminous efficiency.

1 Substrate
2 Anode
3 Hole injection layer
4 hole transport layer
5 Light emitting layer
6 Hole blocking layer
7 Electron transport layer
8 Electron injection layer
9 Cathode
10 hole extraction layer 11 photoelectric conversion layer 12 electron extraction layer

Claims (11)

An organic compound represented by the following formula (1):

(In the formula, Ar ¹ represents an aromatic ring which may have a substituent , and R ¹ and R ² are bonded to each other to form a naphthalene ring, a phenanthrene ring, or a quinoline ring together with ring A. N represents an integer of 0 to 2. Further , the dibenzofuran ring, the anthracene ring and the benzene ring in the formula may have a substituent other than the linking site.   In the said Formula (1), n is 0, The organic compound of Claim 1 characterized by the above-mentioned.   The organic compound according to claim 1 or 2, wherein in the formula (1), the ring A is a benzene ring.   An organic electroluminescent element material comprising the organic compound according to any one of claims 1 to 3.   The composition for organic electroluminescent elements characterized by containing the organic compound and solvent as described in any one of Claims 1-3. In an organic electroluminescent device having an organic layer between an anode and a cathode,
An organic electroluminescent device, wherein the organic layer includes a layer formed using the composition for an organic electroluminescent device according to claim 5.   The organic electroluminescent device according to claim 6, wherein the layer formed using the composition for an organic electroluminescent device is a light emitting layer.   The organic electroluminescent device according to claim 7, wherein the organic electroluminescent device according to claim 7, further comprising a hole transport layer adjacent to the light emitting layer, wherein the hole transport layer is a layer formed by a wet film forming method.   The organic electroluminescent device according to claim 8, wherein the hole transport layer is a layer formed by crosslinking a crosslinkable compound.   An organic EL display device comprising the organic electroluminescent element according to claim 6.   Organic EL lighting characterized by including the organic electroluminescent element as described in any one of Claims 6-9.

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