JP6260894B2 - Compound and organic electroluminescence device - Google Patents

Description

  The present invention relates to a compound and an organic electroluminescence (hereinafter referred to as organic EL) device provided with a hole transport layer containing the compound.

The organic EL element is usually constituted by laminating an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode in this positional relationship on a transparent substrate.
The light emission of the organic EL element is (1) holes and electrons are injected from the electrodes, (2) the injected holes and electrons are transported, (3) the holes and electrons are recombined in the light emitting layer, (4) The light-emitting material forms an electronically excited state, and (5) it emits energy as light when returning from the electronically excited state to the ground state.

When the luminescent material obtains energy and enters an excited state, a singlet excited state (S ₁ ) and a triplet excited state (T ₁ ) are generated with a probability of 1: 3.
In general, the fluorescent material can convert only the energy from S ₁ into light, whereas the phosphorescent material also converts the energy from T ₁ into light. When the phosphorescent material is used for the element, higher efficiency of the organic EL element can be expected (Non-Patent Document 1, Non-Patent Document 2).

  In general, the phosphorescent material is used in a method of being contained in the host material. Holes and electrons injected from the electrode recombine in the light-emitting layer formed of the host material and phosphorescent material (guest material), and the energy of the excited host material moves to the guest material. A certain phosphorescent material is excited and emitted as light energy, whereby efficient light emission can be obtained.

In order to enable efficient energy transfer from the host material to the guest material, it is desirable that the T ₁ energy of the host material is larger than the T ₁ energy of the phosphorescent material that is the guest (Non-Patent Document 3). If towards the T ₁ energy of the guest material is large, it will be going on opposite energy transfer from the guest to the host, because it becomes a factor that hinders the efficiency of light emission.

  Here, in order to increase the recombination efficiency, which is one of the factors of the external quantum efficiency of the organic EL device, the holes and electrons are efficiently recombined in the light emitting layer. It is necessary to adjust the transportation balance.

  To adjust the transport balance of holes and electrons, the hole mobility of hole injection materials, hole transport materials, electron mobility of electron injection materials, electron transport materials, charge injection barriers at layer interfaces, The balance must be adjusted after considering many factors such as the thickness of each film.

  However, the hole and electron transport properties of the material itself differ depending on the material, and a charge injection barrier occurs at the interface between layers made of different materials. It is not easy to combine. Possible cases where the charge injection / transport balance is poor include when there are few holes or electrons, or when either of them is extremely large and passes through without recombination, but the charge flows out to the counter electrode. In such a case, there is a method in which a charge blocking layer is provided so that the charge is confined in the light emitting layer and the recombination efficiency is increased. Usually, the hole transport layer and the electron transport layer often play the role of blocking outflowing charges and confining the charges in the light emitting layer.

  The characteristics required for the hole transport material of the organic EL element are high hole transport property and low electron transport property from the viewpoint of enhancing recombination efficiency and the like, as well as band gap, ionization potential (IP), electron It is important that the affinity (Ea) value has an appropriate value. It is desirable that the ionization potential be a value between the work function of the anode or the ionization potential of the hole injection material and the ionization potential of the light emitting material, thereby reducing the hole injection barrier to the light emitting layer. The electron affinity is desirably larger than the electron affinity of the light-emitting material, whereby the electron blocking effect can be obtained. Note that the HOMO level is almost synonymous with the ionization potential (IP) which is one of the charge injection indexes, and the LUMO level is almost synonymous with the electron affinity (Ea) in some cases. And it is calculated | required that electrical stability is high from a viewpoint of lifetime extension. In addition, since the thermal stability needs to be high, the glass transition temperature (Tg), the melting point, the thermal decomposition point, and the like are required to be high.

  As a hole transport material, for example, many compounds composed of combinations of tertiary amines and aromatic hydrocarbons such as α-NPD, TPD, NPAPF, Spiro-TTB represented by the following chemical formulas (7) to (9) have been reported. (Non-patent document 4, Non-patent document 5, Patent document 1, Non-patent document 6).

  α-NPD and TPD have glass transition temperatures (Tg) of 95 ° C. and 60 ° C., respectively, and considering the organic EL production process and application (use environment), Tg is desirably at least 100 ° C. or higher. It cannot be said that the thermal stability requirement is satisfied. On the other hand, since the Tg of NPAPF and Spiro-TTB are 166 ° C. and 149 ° C., respectively, it can be said that it is an example of a material that satisfies thermal stability requirements. Moreover, it can be said that the thermal stability of a compound having fluorene or spirofluorene in the central skeleton is relatively high.

  However, even with hole transport materials that are commonly used, there are few materials that are particularly excellent in thermal stability, and even if they are materials that are excellent in thermal stability, all the performance required for hole transport materials is achieved. There are still few materials available, and development is required.

US6586120

Nature, 395, 151 (1998) Nature, 403, 750 (2000) Appl. Phys. Lett. , 83, 569 (2003) Appl. Phys. Lett. , 69, 2160 (1996) Monthly display separate volume "Organic EL display" pp. 51 (1998) Adv. Funct. Mater. 2006, 16,966

It is an object of the present invention to provide a novel compound that has a large band gap and T ₁ energy, is excellent in electrical stability and thermal stability, and can be used in a hole transport layer of an organic EL device. . It is another object of the present invention to provide an organic EL device having a long lifetime and high luminous efficiency, which is provided with a hole transport layer containing the above compound.

  As a result of the study, the inventors have found that the compound having a central skeleton of spirobifluorene represented by the following general formula (1) and further containing aminodibenzothiophene represented by the following general formula (2) can be provided.

The compound of the present invention can also be suitably used as a hole transport material for organic EL devices. When the compound of the present invention is used for a hole transport layer, a highly efficient and long-life organic EL device can be obtained. I found out that

  The reason why high efficiency and long life of the organic EL element can be achieved by using the compound represented by the general formula (1) as a hole transport material is not necessarily clear, but the inventors have described the reason as follows. It is estimated as follows.

  The hole transport material of the organic EL element has positive charge transport properties such as a high hole transport property and a low electron transport property from the viewpoint of increasing the charge recombination efficiency in the light emitting layer. From the viewpoint of enhancing hole injection / electron blocking characteristics, it has a large band gap and appropriate HOMO and LUMO levels. Furthermore, it is a material with high electrical and thermal stability from the viewpoint of extending the life. Ideally.

  In the compound of the present invention, it is considered that the collapse of molecular planarity due to the central skeleton composed of spirobifluorene contributes to the expansion of the band gap. However, when the planarity of the molecule is lost, there is a demerit that the electrical characteristics usually deteriorate. Nevertheless, the material of the present invention not only has an appropriate HOMO and LUMO level while having a large band gap by having an aminodibenzothiophene skeleton in addition to a spirobifluorene skeleton in the molecule, High electrical stability and thermal stability can be provided.

Further the inventors found that in order to prevent reverse energy transfer in the light-emitting layer, the T ₁ energy of the host material is focused on that must be greater than the T ₁ energy of the guest material, the efficiency due to the reverse energy transfer The phenomenon of the decrease was considered to be related to the hole transport material in contact with the light emitting layer and the electron transport material. That is, from the viewpoint of suppressing the reverse energy transfer described above, it is desirable that the T ₁ energy of the hole transport material is larger than that of the light emitting material.
In this regard, the compounds of the present invention, since it has a relatively large the T ₁ energy, particularly in the green to red organic EL element, high efficiency can be estimated to contribute to the long life.

The gist of the present invention is as follows.
(A) A compound represented by the following general formula (1).

X ^{1 to} X ⁴ are each independently selected from hydrogen or any one of the following general formula (2), and at least one of X ^{1 to} X ⁴ is the following general formula (2).

R ^{1 to} R ⁶ are each independently selected from hydrogen, an alkyl group that may have a substituent, or a halogen group, and each may be independently present in one or more, When two or more are present, they may be the same or different groups.
Y represents an aromatic cyclic group which may have a substituent.

(B) X ^{1 to} X ⁴ in the general formula (1) are each independently selected from hydrogen, the following general formula (3), or the following general formula (4), and X ^{1 to} X The compound according to claim 1, wherein at least one of ^{4 is represented by} the following general formula (3) or the following general formula (4).

R ^{1 to} R ⁶ are each independently selected from hydrogen, an alkyl group that may have a substituent, or a halogen group, and each may be independently present in one or more, When two or more are present, they may be the same or different groups.
Y represents an aromatic cyclic group which may have a substituent.
(C) The compound according to (a) or (b), wherein X ^{1 to} X ⁴ are other than hydrogen.
(D) The compound according to (a) or (b), wherein X ⁴ is hydrogen.
(E) The compound according to (a) or (b), wherein X ³ and X ⁴ are hydrogen.
(F) The compound according to (a) or (b), wherein X ² and X ⁴ are hydrogen.
(G) The compound according to (a) or (b), wherein X ² , X ³ and X ⁴ are hydrogen.
(H) Any one of (a) to (g), wherein the bonding positions of X ^{1 to} X ⁴ are the 2nd, 7th, 2 ′ and 7 ′ positions of the spirobifluorene skeleton, respectively. Compound described in 1.
(I) The compound according to any one of (a) to (h), wherein Y is a phenyl group.
(J) The compound according to any one of (a) to (i), wherein R ^{1 to} R ⁶ are hydrogen.
(K) A compound represented by the following chemical formula (5).

  (L) A compound represented by the following chemical formula (6).

(M) an organic electroluminescence device comprising an electrode, an anode, and a layer formed of an organic compound between these electrodes,
The organic electroluminescent element characterized by including the compound in any one of (a)-(l) in the layer formed with the said organic compound.
(N) an organic electroluminescence device containing a charge transport material between an anode, a cathode, and both electrodes,
An organic electroluminescence device comprising the compound according to any one of (a) to (l) in the charge transport material.
(O) an organic electroluminescent device comprising a positive hole, a negative electrode, and a hole transport layer between both electrodes,
An organic electroluminescence element comprising the compound according to any one of (a) to (l) in the hole transport layer.
(P) An organic electroluminescence device comprising a light emitting layer and a hole transport layer layer between an anode, a cathode, and both of these electrodes,
The light emitting layer includes a host material and a guest material made of a light emitting material,
The host material is an electron transporting material or a charge transporting material of both electrons and holes,
An organic electroluminescence element comprising the compound according to any one of (a) to (l) in the hole transport layer.
(Q) The organic electroluminescence device according to (p), wherein the guest material is a phosphorescent material.

According to the present invention, it is possible to provide a compound that has a large band gap and T ₁ energy, is excellent in electrical stability and thermal stability, and can be used in a hole transport layer of an organic EL device.
Furthermore, it is possible to provide an organic EL device having a long lifetime and high luminous efficiency, which includes a hole transport layer containing the above compound.

(About the aspect of a compound)
X ^{1 to} X ⁴ in the following general formula (1) are each independently selected from hydrogen or any one of the following general formula (2), the following general formula (3), or the following general formula (4), At least one of X ¹ to X ⁴ is any one of the following general formula (2), the following general formula (3), or the following general formula (4).

R ^{1 to} R ⁶ in the above general formulas (1) to (4) are from the viewpoint of improving film quality after film formation, improving electrical stability and thermal stability, and easiness of compound synthesis and purification. To be elected.

R ^{1 to} R ⁶ are each independently selected from any of hydrogen, an optionally substituted alkyl group, and a halogen group. The substituent of the alkyl group that may have a substituent in R ^{1 to} R ⁶ is selected from any of an alkyl group, an alkoxy group, and a halogen group.

The alkyl group that may have a substituent in R ^{1 to} R ⁶ may be linear or cyclic. The linear alkyl group preferably has 1 to 18 carbon atoms from the viewpoint of solubility in a general-purpose organic solvent, film-forming properties at the time of creating an organic EL element, and from the viewpoint of glass transition temperature, steric hindrance, etc. C1-C6 is more preferable. The linear alkyl group having 1 to 18 carbon atoms is methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group. Tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group. The cyclic alkyl group preferably has 3 to 18 carbon atoms, and preferably has 3 to 8 carbon atoms from the viewpoint of glass transition temperature, steric hindrance and the like. The cyclic alkyl group includes, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, a cyclododecyl group, a cyclotridecyl group, a cyclotridecyl group, Examples include a cycloalkyl group such as a tetradecyl group, a cycloheptadecyl group, and a cyclohexyl group, or a polycyclic alkyl group such as a bicycloalkyl group and a tricycloalkyl group.

The substituents of the alkyl group that may have a substituent in R ^{1 to} R ⁶ may be substituted two or more, and each may be different.
The alkyl group selected as the substituent of the alkyl group that may have a substituent is the sum of the alkyl group serving as the main chain and the alkyl group that is the substituent, from the viewpoint of film-forming properties during the preparation of the organic EL device. The number of carbons thus obtained is preferably 1-18, and more preferably the total number of carbons is 1-6 from the viewpoint of glass transition temperature, steric hindrance and the like.

  The case where an alkyl group is selected as a substituent of the alkyl group which may have a substituent is, for example, 1-methylethyl group, 1-methylpropyl group, 1-ethylpropyl group, 1-n-propylpropyl Group, 1-methylbutyl group, 1-ethylbutyl group, 1-propylbutyl group, 1-n-butylbutyl group, 1-methylpentyl group, 1-ethylpentyl group, 1-n-propylpentyl group, 1-n-pentyl group Pentyl group, 1-methylhexyl group, 1-ethylhexyl group, 1-n-propylhexyl group, 1-n-butylhexyl group, 1-n-pentylhexyl group, 1-n-hexylhexyl group, 1-methylheptyl Group, 1-ethylheptyl group, 1-n-propylheptyl group, 1-n-butylheptyl group, 1-n-pentylheptyl group, 1-n-heptylheptyl 1-methyloctyl group, 1-ethyloctyl group, 1-n-propyloctyl group, 1-n-butyloctyl group, 1-n-pentyloctyl group, 1-n-hexyloctyl group, 1-n-heptyl Octyl group, 1-n-octyloctyl group, 1-methylnonyl group, 1-ethylnonyl group, 1-n-propylnonyl group, 1-n-butylnonyl group, 1-n-pentylnonyl group, 1-n-hexylnonyl Group, 1-n-heptylnonyl group, 1-n-octylnonyl group, 1-n-nonylnonyl group, 1-methyldecyl group, iso-propyl group, t-butyl group, 2-methylbutyl group, 2-ethylbutyl group, 2 -N-propylpentyl group, 2-methylhexyl group, 2-ethylhexyl group, 2-n-propylhexyl group, 2-n-butylhexyl group, 2-methylheptyl group Group, 2-ethylheptyl group, 2-n-propylheptyl group, 2-n-butylheptyl group, 2-n-pentylheptyl group, 2-methyloctyl group, 2-ethyloctyl group, 2-n-propyl Octyl group, 2-n-butyloctyl group, 2-n-pentyloctyl group, 2-n-hexyloctyl group, 2-methylnonyl group, 2-ethylnonyl group, 2-n-propylnonyl group, 2-n-butylnonyl Group, 2-n-pentylnonyl group, 2-n-hexylnonyl group, 2-n-heptylnonyl group, 2-methyldecyl group, 2,3-dimethylbutyl group, 2,3,3-trimethylbutyl group, 3- Methylbutyl group, 3-methylpentyl group, 3-ethylpentyl group, 4-methylpentyl group, 4-ethylhexyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentene Tyl group, 2,4,4-trimethylpentyl group, 2,3,3,4-tetramethylpentyl group, 3-methylhexyl group, 2,5-dimethylhexyl group, 3-ethylhexyl group, 3,5,5 -Trimethylhexyl group, 4-methylhexyl group, 6-methylheptyl group, 3,7-dimethyloctyl group, 6-methyloctyl group, etc. are mentioned.

  The alkoxy group selected as the substituent of the alkyl group which may have a substituent is an alkyl group and its substituent from the viewpoints of solubility in a general-purpose organic solvent, film-forming properties at the time of preparing an organic EL device, and the like. The total number of carbon atoms of the alkoxy groups is preferably 1 to 18, and from the viewpoint of glass transition temperature, steric hindrance and the like, the total number of carbon atoms is more preferably 1 to 6.

  Examples of the halogen group selected as the substituent of the alkyl group that may have a substituent include a fluorine group, a chloro group, a bromo group, and an iodo group, and among these, electrical and thermal stability, and ease of synthesis. From this viewpoint, a fluorine group is preferred.

Here, as described above, R ⁵ and R ⁶ are each selected from hydrogen, an alkyl group, or a halogen group. However, electrical stability, thermal stability, film formability, easiness of synthesis and purification, etc. In view of the above, hydrogen or a methyl group is most preferable. Further, when a methyl group is selected, it is considered preferable that substitution is made at the 2-position or 4-position, which is the reaction point of dibenzothiophene, to increase electrical stability.

  Further, Y in the general formulas (2) to (4) represents electrical effects such as HOMO level, LUMO level and band gap of the compound, thermal stability such as melting point and glass transition temperature, and steric hindrance effect. Selected from the perspective.

Y represents an aromatic cyclic group which may have a substituent.
The aromatic cyclic group represents an aromatic hydrocarbon group or a heterocyclic group.

  Examples of the aromatic cyclic group which may have a substituent represented by Y include an aromatic hydrocarbon group having 6 to 30 carbon atoms and an aromatic heterocyclic group having 1 to 30 carbon atoms.

Here, examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms represented by Y include 6π electron system, 10π electron system, 12π electron system, and 14π electron system aromatic hydrocarbon ring groups. Are phenyl, biphenyl, naphthyl, terphenyl, anthryl, azulenyl, fluorenyl, pyrenyl, phenanthryl, naphthyl, etc., and among them, phenyl group, naphthyl are particularly preferred from the viewpoint of obtaining appropriate electrical effects and thermal stability. Group and biphenyl group are preferred.
In addition, in the case of a biphenyl group, when an alkyl group such as a methyl group is introduced into the portion corresponding to the ortho position of the phenyl-to-phenyl bond, the biphenyl skeleton is twisted due to steric hindrance, and the spread of the π-conjugated system is suppressed. In particular, 2,2′-dimethyl-1,1′-biphenyl is preferable because a good electrical effect can be obtained.

  Examples of the aromatic heterocyclic group represented by Y include 6π electron system, 10π electron system, 12π electron system, and 14π electron system aromatic heterocyclic groups. Specifically, thienyl, furyl, pyrrolyl, thiazolyl, Isothiazolyl, pyrazolyl, oxazolyl, isooxolyl, pyridyl, pyridazyl, oxadiazolyl, imidazolyl, triazyl, thiadiazolyl, benzothiazolyl, benzimidazolyl, benzoxazolyl, benzooxadiazolyl, benzotriazolyl, benzothiadiazolyl, benzoselenadiazolyl, thieno [2,3-b] thienyl, thieno [3,2-b] thienyl, thieno [3,4-b] thienyl, 9-oxofluorenyl, carbazolyl, dibenzothiophenyl, silafluorenyl, selenofluorenyl, xanthenyl The phenant Lil, Fenajiriru, Fenikisajiriru, and the like. Of these, a dibenzothiophenyl group is particularly preferable from the viewpoint of obtaining an appropriate electrical effect.

Two or more substituents of the aromatic cyclic group which may have a substituent may be substituted, or may be different from each other.
Examples of the substituent of the aromatic cyclic group which may have a substituent include a linear, branched, or cyclic alkyl group, a halogen group, an amino group, a nitro group, and a cyano group. Moreover, as an alkyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group etc. are preferable from a viewpoint of obtaining an appropriate steric effect. As the halogen, a fluorine group is preferable from the viewpoint of easy synthesis.

X ^{1 to} X ⁴ in the general formula (1) are each independently selected from hydrogen or any one of the following general formula (2), the following general formula (3), or the following general formula (4). ^At least one of ¹ to X ⁴ is any one of the following general formula (2), the following general formula (3), or the following general formula (4). Among these, from the viewpoint of ease of synthesis, among X ^{1 to} X ⁴ , it is preferable that X ³ and X ⁴ are hydrogen, or X ² and X ⁴ are hydrogen. Also, electrical stability, in terms of ease of synthesis, it is preferred that X ¹ to X ⁴ is a general formula (3), or general formula (4). Furthermore, from the viewpoint of ease of synthesis, it is preferable that the bonding positions of X ^{1 to} X ⁴ are the 2nd, 7th, 2 'and 7' positions of the spirobifluorene skeleton, respectively.

Specific examples of the compounds are shown below.
^X 1 to X ⁴ in the general formula (1) is, as represented by the general formula (2) include compounds of the following compounds (11) - (20).

Among X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are represented by the general formula (2), for example, the compound groups of the following compounds (21) to (32) may be mentioned. .

Among X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are represented by the general formula (2), for example, the compound groups of the following compounds (33) to (44) may be mentioned. .

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (2) and a methyl group is selected as R, for example, the following compounds (45) to The compound group of (56) is mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (2) and a methyl group is selected as R, for example, the following compounds (57) to The compound group of (68) is mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (2) and a t-butyl group is selected for R, for example, the following compound (69 ) To (80).

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (2) and a t-butyl group is selected as R, for example, the following compound (81 ) To (92).

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (2) and a phenyl group is selected as Y, for example, the following compounds (93) to The compound group of (102) is mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (2) and a phenyl group is selected as Y, for example, the following compounds (103) to The compound group of (114) is mentioned.

Among X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (2) and Y is a 2,2′-dimethyl-1,1′-biphenyl group Is, for example, a group of compounds (115) to (122) shown below.

Among X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (2) and a 2,2′-dimethyl-1,1′-biphenyl group is selected as Y Includes, for example, compound groups (123) to (132) shown below.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (3), for example, the compound groups of the following compounds (133) to (136) are exemplified. .

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (3) and a phenyl group is selected as Y, for example, the following compounds (137) to The compound group of (140) is mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (3), examples include the compound groups of the following compounds (141) to (144). .

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (3) and a phenyl group is selected as Y, for example, the following compounds (145) to The compound group of (148) is mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (4), for example, the following compound groups of the compounds (149) to (152) are exemplified. .

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ⁴ are the general formula (4) and a phenyl group is selected as Y, for example, the following compounds (153) to The compound group of (156) is mentioned.

Among X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (4), for example, the following compound groups of the compounds (157) to (160) are exemplified. .

Of X ^{1 to} X ⁴ in the general formula (1), when X ¹ and X ² are the general formula (4) and a phenyl group is selected as Y, for example, the following compounds (161) to The compound group of (164) is mentioned.

Among X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (2), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. In the case of substitution, for example, the following compound groups (165) to (168) can be mentioned.

Among X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (2), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. When it is substituted and Y is a phenyl group, for example, the following compound groups (169) to (172) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (2), and X ¹ and X ² are substituted at positions 2 and 7 of the central skeleton, spirobifluorene In the case where it is, for example, the following compound groups (173) to (176) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (2), and X ¹ and X ² are substituted at positions 2 and 7 of the central skeleton, spirobifluorene In the case where Y is a phenyl group, for example, the following compound groups (177) to (180) may be mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (3), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. In the case of substitution, for example, the following compound groups (181) to (184) can be mentioned.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (3), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. When it is substituted and Y is a phenyl group, for example, the following compound groups (6) and (185) to (187) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (3), and X ¹ and X ² are substituted at the 2nd and 7th positions of the central skeleton, spirobifluorene In the case where it is, for example, the following compound groups (188) to (191) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (3), and X ¹ and X ² are substituted at the 2nd and 7th positions of the central skeleton, spirobifluorene When Y is a phenyl group, for example, the following compound groups (5) and (193) to (194) are exemplified.

Among X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (4), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. In the case of substitution, for example, the following compound groups (195) to (198) can be mentioned.

Among X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ⁴ are the general formula (4), and X ¹ and X ⁴ are in the 2,2 ′ positions of the central skeleton, spirobifluorene. When it is substituted and Y is a phenyl group, for example, the following compound groups (199) to (202) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (4), and X ¹ and X ² are substituted at positions 2 and 7 of the central skeleton, spirobifluorene In the case where it is, for example, the following compound groups (203) to (206) are exemplified.

Of X ^{1 to} X ⁴ in the general formula (1), X ¹ and X ² are the general formula (4), and X ¹ and X ² are substituted at positions 2 and 7 of the central skeleton, spirobifluorene In the case where Y is a phenyl group, for example, the following compound groups (207) to (210) are exemplified.

  In addition, the compound quoted here is an illustration, Comprising: It is not limited to this.

(About synthesis)
A typical synthesis method of the compound according to the present invention will be described.
A typical synthesis method of the compound represented by the following general formula (211) will be described.

  As shown in the following reaction formula (S1), the compound represented by the general formula () is a halogenated dibenzothiophene derivative using a general halogenation reaction, followed by the halogenation represented by the following general formula (213). It is synthesized by performing an N-arylation reaction between dibenzothiophene and an aromatic hydrocarbon having an amino group represented by the following general formula (214).

  Examples of the halogenation reaction include a method of directly reacting halogens such as bromine and iodine in the presence of a catalyst, and a method of using a halogenating agent. Halogenating agents include chlorinating agents, brominating agents, and iodinating agents. Examples of the chlorinating agent include N-chlorosuccinimide (NCS) and the like, and examples of the brominating agent include N-bromosuccinimide (NBS) and dibromoisocyanuric acid (DBI). Examples thereof include N-iodosuccinimide (NIS), 1,3-diiodo-5,5′-dimethyl hirudantoin (DIH) and the like.

  Next, the synthesis of halogenated dibenzothiophenes with different halogen substitution positions will be described.

  In order to obtain a compound represented by the following general formula (215) in which the 4-position of dibenzothiophene is halogenated, for example, a method represented by the following reaction formula (S2) may be mentioned.

  That is, an anionized carbon can be halogenated using a dihalogenated ethane such as 1,2-dichloroethane, 1,2-dibromoethane, or 1,2-diiodoethane. The 4-position can be preferentially halogenated.

  In order to obtain a compound in which the 2-position of dibenzothiophene is halogenated, for example, a method shown in the following reaction formula (S3) can be mentioned.

  For example, by reacting NBS, which is a kind of halogenating agent, with dibenzothiophene, the 2-position of dibenzothiophene is preferentially halogenated. It is also possible to introduce two or more halogen groups by adjusting the amount of the halogenating agent.

  Also, for example, J. Org. Org. Chem. , 2006, 71, 6291 applied to the method shown in the following reaction formula (S4), the dibenzothiophene halogenated at the 1-position shown in the following general formula (222) and its Derivatives can be synthesized.

  Further, by using the method shown in the following reaction formula (S5) to which the method described in Tetrahedron, 2002, 58, 1709 is applied, dibenzothiophene in which the 3-position shown in the following general formula (227) is halogenated, The derivative can be synthesized.

  As shown in the following reaction formula (S6), a halogenated dibenzothiophene and an aromatic cyclic group into which an amino group has been introduced are converted into, for example, a Buchwald-Hartwig reaction (for example, Org. Synth., 2002, 78, 23). , Ullmann reaction (for example, Angew. Chem., Int. Ed. 2003, 42, 5400) and the like are applied to synthesize the compound described in the general formula (211). it can.

  In addition, as shown in the following reaction formula (S7), even when N-arylation is performed using a dibenzothiophene derivative having an amino group introduced therein and a halogenated aromatic cyclic group, the above general formula ( 211) can be synthesized similarly.

  As shown in the following reaction formula (S8), an alkyl group or the like can be introduced into dibenzothiophene by using a halogenated dibenzothiophene and an alkyl Grignard reagent, for example.

  As shown in the following reaction formula (S9), if a Suzuki coupling reaction (for example, Chem. Rev., 1995, 95, 2457) or the like is used, it is also possible to introduce an aromatic cyclic group into dibenzothiophene. . In addition, as the boronic acid derivative, R may be any boronic acid derivative such as hydrogen, methyl, isopropyl and the like as required.

  The above-mentioned J. Org. Chem. , 2006, 71, 6291, the method shown in the following reaction formula (S10) is also possible.

  A dibenzothiophene derivative having a substituent R introduced therein, represented by the following general formula (234), can also be synthesized by applying the above reaction.

  For example, the compound represented by the general formula (234) can be synthesized by the method represented by the following reaction formula (S11).

  In order to introduce spirobifluorene having a central skeleton in the compound of the present invention, for example, compounds represented by the following general formulas (239) and (240) can be used as intermediates.

  As shown in the following reaction formula (S12), in general halogenation, the 2nd, 2 ', 7th and 7' positions of spirofluorene are preferentially halogenated.

However, after the second position of spirofluorene is halogenated, which position is preferentially halogenated among the 2′-position, the 7-position and the 7′-position depends on the reaction conditions.
Examples of the halogenation reaction include a method of directly reacting halogens such as bromine and iodine in the presence of a catalyst, and a method of using a halogenating agent. Halogenating agents include chlorinating agents, brominating agents, and iodinating agents. Examples of the chlorinating agent include N-chlorosuccinimide (NCS) and the like, and examples of the brominating agent include N-bromosuccinimide (NBS) and dibromoisocyanuric acid (DBI). Examples thereof include N-iodosuccinimide (NIS), 1,3-diiodo-5,5′-dimethyl hirudantoin (DIH) and the like.

  For example, Org. Lett. , 12, 24, 5648 (2010), a halogenated spirofluorene can also be synthesized by using the method shown in the following reaction formula (S13) using the method described in the following.

  Spirofluorenes having different halogen substitution positions can be synthesized by using the above method. For example, 2,7-halogenated spirofluorene can be synthesized by the method shown in the following reaction formula (S14).

  A spirofluorene skeleton into which a substituent is introduced can also be synthesized by the method shown in the following reaction formula (S15) applying the above reaction formula.

  The synthesis of 2,2'-halogenated spirofluorene is described, for example, in Chem. Rev. , 2007, 107, 1011 can be applied, and the method shown in the following reaction formula (S16) can be used.

  The synthesis of 4,4′-halogenated spirofluorene is described in, for example, Org. Lett. , 12, 24, 5648 (2010), the method shown in the following reaction formula (S17) can be used.

  Furthermore, a spirofluorene can also be substituted by the method shown in the following reaction formula (S18).

In addition, the Chem. Rev. , 2007, 107, 1011, various spirofluorene derivatives can be synthesized.
As shown in the following reaction formulas (S19) and (S20), an N-arylation reaction between the general formula (234) and the above general formula (239) or (240) is performed to obtain the following general formula (263). ) Or (264) can be synthesized.

(About physical property evaluation)
The purity of the compound can be measured, for example, by high performance liquid chromatography (HPLC). High-performance liquid chromatography applies pressure to the mobile phase into which the material is introduced, passes the solvent through the mobile phase at a high flow rate, separates the material (mixture) with a column, and detects the separated material with a detector. This is a method to measure the purity of the data.
A normal layer system or a reverse layer system can be used for the column. Normal layer chromatography refers to a separation system in which the polarity of the stationary phase is higher than the polarity of the mobile phase, and alumina or the like is used for the stationary phase, and a solvent with a small polarity such as hexane can be used for the mobile phase. Reverse-layer chromatography refers to a separation system in which the polarity of the mobile phase is higher than that of the stationary phase. Hydrophobic silica is used for the stationary phase, and a polar solvent such as methanol or acetonitrile is used for the mobile phase. Can be used.
Various detectors can be used according to the physical properties of the data. For example, an absorptiometric detector (UV / VIS), a fluorescence detector (FLD), a mass spectrometer (MS), etc. are mentioned.

The molecular weight of the compound can be measured by mass spectrometry (MS). Mass spectrometry is performed by applying a high voltage in a vacuum to the material introduced from the material introduction unit, ionizing the material, separating the ions according to the mass-to-charge ratio, and detecting them by the detection unit. .
The data introduction unit can be directly connected to gas chromatography (GC / MS), high performance liquid chromatography (LC / MS), and capillary electrophoresis (CE / MS), and measures MS and also measures purity. be able to. A direct injection method (DI / MS) that directly ionizes the material may be employed.
Various ionization methods are adopted for the ion source. For example, an electron ionization method (EI), a fast atom bombardment method (FAB), an electrospray ionization method (ESI), an inductively coupled plasma method (ICP), and the like can be given.

  A nuclear magnetic resonance spectrum (NMR) can be used for identification of the compound. In NMR measurement, since chemical shift and coupling information can be known from the bonding state of atoms and the like, a spectrum unique to the compound can be obtained and the compound can be identified. The measurement is performed by dissolving a small amount of data in a heavy solvent.

  The thermal stability of the compound can be evaluated by differential scanning calorimetry (DSC). The DSC measurement is performed by detecting a difference in the amount of heat from the standard sample when the material undergoes a thermal change such as phase transition or melting. DSC can know the melting point and glass transition temperature of a compound.

By measuring the UV-visible absorption spectrum (UV / VIS), fluorescence spectrum (PL), and phosphorescence spectrum of a compound, not only can the UV absorption wavelength, fluorescence wavelength, and phosphorescence wavelength unique to the compound be known, but also the band gap of the compound. It is possible to know information such as fluorescence quantum yield and T ₁ energy.

The HOMO level and LUMO level of a compound can be measured by cyclic voltammetry (CV). As an idea similar to the HOMO level, ionization potential (IP) measurement is also used.
Furthermore, a method is also used in which an optical band gap is obtained from the UV absorption wavelength, and a LUMO level (or Ea) is obtained by calculation from the HOMO level (or IP).

(About organic EL elements)
The organic EL device of the present invention is characterized by using the compound of the present invention for a hole transport layer.

In an organic EL element, an anode, a hole injection layer, a hole transport layer (electron blocking layer), a light emitting layer, an electron transport layer (hole blocking layer), an electron injection layer, and a cathode are laminated on this substrate in this positional relationship. Configured.
The organic EL element does not need to be entirely formed of an organic material, and an inorganic material may be used for an electrode, a hole injection layer, an electron injection layer, or the like.
Of the layers forming the organic EL element, any of the hole injection layer, the electron transport layer, and the electron injection layer may be omitted.
The organic EL element includes a bottom emission type element that extracts light from the substrate side and a top emission type element that extracts light from the side opposite to the substrate, and the organic EL element of the present invention can take either method.

The material used for the substrate may differ between the top emission type element and the bottom emission type element. A transparent substrate is used for the bottom emission type element. On the other hand, in the top emission type, not only a transparent substrate but also an opaque substrate can be used.
As a material used for the substrate, various kinds of glass such as quartz glass, soda glass, and Pyrex can be used. Various plastic substrates such as polycarbonate, polyacrylate, polyethylene terephthalate, and the like can also be used. Further, two or more of these can be used in combination.

  For the bottom emission type element, a transparent conductive material is generally used for the anode. The top emission type is not particularly limited, but a reflective electrode may be used. The role of the anode is to inject holes into the hole injection layer or the hole transport layer. For this reason, materials functioning as the anode, such as various metal materials having a relatively large work function and various alloys, are used for the anode. Examples thereof include gold, copper iodide, tin oxide, aluminum-doped zinc oxide (ZnO: Al), indium tin oxide (ITO), indium zinc oxide (IZO), and fluorine tin oxide (FTO). Among these, ITO, IZO, and FTO are preferable from the viewpoint of transparency and work function.

The material used for the hole injection layer is selected from the viewpoint of the work function of the anode and the IP of the hole transport layer, charge transport characteristics, and the like. Examples thereof include compounds represented by the following chemical formulas (265) to (282). Among these, poly (3,4-ethylenedioxythiophene) represented by the following chemical formula (275): poly (styrene sulfonate) (PEDOT: PSS), copper phthalocyanine (CuPc) represented by the following general formula (267), molybdenum Oxides (MoOx), vanadium oxide (V ₂ O ₅ ), and the like are preferable, and PEDOT: PSS may also be suitably used. As long as the compound has appropriate IP and charge transport properties, various organic compounds and inorganic compounds can be selected regardless of whether they are low molecular or high molecular. Also, two or more of these materials can be used in combination.

  The compound of the present invention can be used for the hole transport layer. Since the compound has an orthophenylene central skeleton and an aminodibenzothiophene skeleton, it has a wide band gap, appropriate HOMO and LUMO levels, and is excellent in electrical stability and thermal stability. Therefore, the charge recombination efficiency in the light emitting layer can be increased, and a long-life organic EL element with higher light emission efficiency can be realized, which is preferable.

  Although the compound of this invention can also be used independently, it can also be used 1 type, or 2 or more types of existing hole transportable materials can be mixed, and can also be used by laminating | stacking 1 layer or 2 layers or more. . Examples of the hole transporting material include compounds represented by the following general formulas (7) to (10) and (283) to (313).

A fluorescent material or a phosphorescent material can be used for the light-emitting layer. The light-emitting material can also be used by containing a light-emitting material (guest) in a host material that performs charge transport and charge recombination.
As the host material, a dual charge transporting material having a hole transporting property and an electron transporting property can be used. Further, since the hole transporting material of the present invention is also excellent in electron blocking performance, an electron transporting material can be used as the host material.

When a phosphorescent material is selected as the guest material, it is preferable to select the host material so that the T ₁ energy of the host material is higher than the T ₁ energy of the guest material.

  Examples of the host material include compounds represented by the following general formulas (314) to (336).

In order to effectively transfer energy from the host material, it is preferable that the emission wavelength of the host material and the absorption wavelength of the guest material overlap. Further, when the guest material is a phosphorescent material, the T ₁ energy of the host material is preferably larger than the T ₁ energy of the guest material.

  The light emitting material is not particularly limited. Examples of the fluorescent material include compounds represented by the following general formulas (337) to (358). Examples of the phosphorescent material include the following general formulas (359) to (387). The compound shown by these is mentioned.

  As a material used for an electron carrying layer, the compound shown by the following general formula (388)-(415) is mentioned, for example. When an electron transport layer having an appropriate LUMO level is provided between the light-emitting layer and the cathode or the electron injection layer, the electron injection barrier from the cathode or the electron injection layer to the electron transport layer is relaxed. The barrier for electron injection into the light emitting layer can be relaxed. Moreover, when the material has an appropriate HOMO level, holes that do not recombine in the light emitting layer but flow out to the counter electrode are blocked, holes are confined in the light emitting layer, and recombination efficiency in the light emitting layer is increased. be able to. However, when the electron injection barrier is not a problem and the electron transporting capability of the light emitting layer is sufficiently high, it is not necessary to provide an electron transporting (hole blocking) layer, and the layer may be omitted. .

The material used for the electron injection layer is selected from the viewpoint of the work function of the cathode and the LUMO level of the electron transport layer. When the electron transport layer is not provided, it is selected in consideration of the LUMO level of the light emitting material or the host material described later. The electron injection material may be an organic compound or an inorganic compound.
When the electron injection layer is made of an inorganic compound, for example, lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, cesium carbonate, or the like is used in addition to an alkali metal or an alkaline earth metal. be able to.

The cathode of the organic EL element plays a role of injecting electrons into the electron injection layer or the electron transport layer. For the cathode, materials that act as the cathode, such as various metal materials and various alloys having a relatively small work function, are used. For example, aluminum, silver, magnesium, calcium, gold, indium tin oxide (ITO), indium zinc oxide (IZO), magnesium indium alloy (MgIn), silver alloy, and the like can be given.
When the bottom emission method is employed, an opaque electrode made of metal can be used for the cathode. In addition, the cathode can be a reflective electrode.
When the top emission method is adopted, a transparent electrode such as ITO or IZO can be used for the cathode. Here, since ITO has a large work function, it becomes difficult to inject electrons, and in order to form an ITO film, a sputtering method or an ion beam evaporation method is used. May cause damage. Therefore, in order to improve electron injection and reduce damage to the electron transport layer during film formation, a magnesium layer or a copper phthalocyanine layer can be provided between the electron transport layer and ITO.

(Synthesis of compounds)
Example 1
A compound represented by the following chemical formula (5) was synthesized by the synthesis route (S21) shown below.

  A compound represented by the following chemical formula (418) was synthesized by the method shown below.

  To a 300 mL Schlenk tube equipped with a stirrer and purged with argon, 4-bromodibenzothiophene (13.16 g, 50 mmol), aniline (4.66 g, 50 mmol), palladium acetate (225 mg, 1.0 mmol), toluene (150 mL) , Tri-t-butylphosphine (202 mg, 1.0 mmol) and t-butoxypotassium (5.61 g, 50 mmol) were added, sealed, and stirred at 100 ° C. for 6 hours. Thereafter, the reaction vessel was allowed to cool to near room temperature, the lid was opened, and water (150 mL) was added thereto. The contents were transferred to a separatory funnel, the organic phase and the aqueous phase were separated, the aqueous phase was removed, and the organic phase was further washed with water. The organic phase was dried with sodium sulfate. Thereafter, sodium sulfate was removed by filtration, and the organic phase was concentrated. The concentrated mixture was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the above general formula (418) (yield 10.7 g, Yield 77.8%).

¹ H-NMR, DMSO-d6, δ: 6.85 (t, J = 7.3 Hz, 1H), 6.98 (d, J = 7.8 Hz, 8H), 7.23 (t, J = 8 .3 Hz, 2H), 7.32 (d, J = 7.8 Hz, 1H), 7.45 (t, J = 7.8 Hz, 1H), 7.50-7.53 (m, 2H), 8 .01-8.03 (m, 2H), 8.17 (s, 1H), 8.33-8.35 (m, 1H)

  A compound represented by the following chemical formula (5) was synthesized by the method shown below.

  A 100 mL Schlenk tube equipped with a stir bar and purged with argon was charged with N-phenyldibenzo [b, d] thiophen-4-amine (0.55 g, 2.0 mmol), 2,7-dibromo-9,9'-spirobi. Fluorene (0.47 g, 1.0 mmol), palladium acetate (9.0 mg, 0.04 mmol), toluene (40 mL), tri-t-butylphosphine (8.1 mg, 0.04 mmol), and t-butoxypotassium ( 0.22 g, 2.0 mmol) was added and sealed, followed by stirring at 100 ° C. for 20 hours. Thereafter, the reaction vessel was allowed to cool to near room temperature, the lid was opened, and water (30 mL) was added thereto. The contents were transferred to a separatory funnel, the organic phase and the aqueous phase were separated, the aqueous phase was removed, and the organic phase was further washed with water. The organic phase was dried with sodium sulfate. Thereafter, sodium sulfate was removed by filtration, and the organic phase was concentrated. The concentrated mixture was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the general formula (5) (yield 0.47 g, Yield 54.5%).

The purity measurement by HPLC was performed under the following conditions.
Column “Inert Sustain, C18, 5 μm, 4.6 mm × 150 mm (reverse phase system)”, eluent “acetonitrile: THF = 90: 10”, flow rate “1.0 ml / min”, UV detector “254 nm”

  The compound was identified by molecular NMR peak coincident with the target compound in MS spectrum and proton NMR.

¹ H-NMR, CDCl ₃ δ: 6.07 (d, J = 1.8 Hz, 2H), 6.74 (d, J = 7.8 Hz, 2H), 6.83 (d, J = 7.8 Hz) 4H), 6.90-6.97 (m, 6H), 7.07-7.18 (m, 8H), 7.38 (t, J = 7.8 Hz, 2H) 7.47-7. 50 (m, 4H), 7.66 (d, J = 7.3 Hz, 2H), 7.82 (d, 8.7 Hz, 2H), 7.88-7.91 (m, 2H), 8. 09 (d, J = 7.0 Hz, 2H), 8.27-8.29 (m, 2H)

Example 2
A compound represented by the following chemical formula (6) was synthesized by the synthesis route (S22) shown below.

A compound represented by the following chemical formula (6) was synthesized by the method shown below.

  A 100 mL Schlenk tube equipped with a stir bar and purged with argon was charged with N-phenyldibenzo [b, d] thiophen-4-amine (0.55 g, 2.0 mmol), 2,2'-dibromo-9,9'-spiro. Bifluorene (0.47 g, 1.0 mmol), palladium acetate (9.0 mg, 0.04 mmol), toluene (40 mL), tri-t-butylphosphine (8.1 mg, 0.04 mmol), and t-butoxypotassium (0.22 g, 2.0 mmol) was added, and after sealing, the mixture was stirred at 100 ° C. for 20 hours. Thereafter, the reaction vessel was allowed to cool to near room temperature, the lid was opened, and water (30 mL) was added thereto. The contents were transferred to a separatory funnel, the organic phase and the aqueous phase were separated, the aqueous phase was removed, and the organic phase was further washed with water. The organic phase was dried with sodium sulfate. Thereafter, sodium sulfate was removed by filtration, and the organic phase was concentrated. The concentrated mixture was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the general formula (6) (yield 0.38 g, Yield 44.0%).

The purity measurement by HPLC was performed under the following conditions.
Column “Inert Sustain, C18, 5 μm, 4.6 mm × 150 mm (reverse phase system)”, eluent “acetonitrile: THF = 90: 10”, flow rate “1.0 ml / min”, UV detector “254 nm”

  The compound was identified by molecular NMR peak coincident with the target compound in MS spectrum and proton NMR.

¹ H-NMR, DMSO-d6 δ: 6.30 (s, 2H), 6.62 (d, J = 7.8 Hz, 2H), 6.81 (d, J = 7.4 Hz, 4H), 6 .89 (dd, J = 2.3 Hz, 8.2 Hz, 2H), 7.00 (q, J = 7.4 Hz, 4H), 7.09 (d, J = 6.9 Hz, 2H) 7.18 -7.28 (m, 6H), 7.44-7.48 (m, 6H), 7.75-7.84 (m, 6H), 8.18 (d, J = 7.8Hz, 2H) , 8.31-8.33 (m, 2H)

  A compound represented by the following chemical formula (217) was synthesized by the method shown below.

To a 300 mL Schlenk tube equipped with a stirrer and purged with argon, 2-bromodibenzothiophene (13.16 g, 50 mmol), aniline (4.66 g, 50 mmol), palladium acetate (225 mg, 1.0 mmol), toluene (150 mL) , Tri-t-butylphosphine (202 mg, 1.0 mmol) and t-butoxypotassium (5.61 g, 50 mmol) were added, sealed, and stirred at 100 ° C. for 18 hours. Thereafter, the reaction vessel was allowed to cool to near room temperature, the lid was opened, and water (150 mL) was added thereto. The contents were transferred to a separatory funnel, the organic phase and the aqueous phase were separated, the aqueous phase was removed, and the organic phase was further washed with water. The organic phase was dried with sodium sulfate. Thereafter, sodium sulfate was removed by filtration, and the organic phase was concentrated. The concentrated mixture was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the above general formula (419) (yield: 7.85 g, Yield 57.1%).
The compound was identified by MS spectrum.

  DSC measurement was performed on the compound represented by the chemical formula (5) (Example 3), the compound represented by the chemical formula (6) (Example 4), and the NPAPF (Comparative Example 1) represented by the chemical formula (9). It was. The results of the glass transition temperature are shown in Table 1.

  As shown in Table 1, the compounds represented by the chemical formulas (5) and (6) have a high Tg and excellent thermal stability like the compound represented by the chemical formula (9), which is said to have relatively high thermal stability. It turns out that it is material.

  A thin film comprising a compound represented by the chemical formula (5) (Example 5), a compound represented by the chemical formula (6) (Example 6), and a compound represented by the chemical formula (9) (Comparative Example 2) was respectively formed on a quartz substrate. Formed. The UV / vis spectrum of each of these thin films was measured using UV-2500PC manufactured by SHIMADZU, and the optical band gap was calculated. The results are shown in Table 2.

Excitation of a thin film made of a compound represented by the chemical formula (5) (Example 7) and a thin film made of a compound represented by the chemical formula (9) (Comparative Example 3) at a wavelength of 300 nm using FluoroMax-4 manufactured by HORIBA. Using a light source, emission spectra were measured at a low temperature of 77 K, and T ₁ energy of each thin film was calculated. The results are shown in Table 3 below.

From the viewpoint of the confinement of the energy, the T ₁ energy of the hole transport layer material is preferably greater than the T ₁ energy of the guest material. From the results shown in the above figure, the hole transport layer composed of the compound represented by the chemical formula (5) (Example 7) is in a triplet excited state (T ₁ ) when Ir (mppy) ₃ is used as a guest material. The energy can be confined. Therefore, it can be presumed that an organic EL element with high luminous efficiency can be obtained by including a hole transport layer containing compound 5 and a light emitting layer using Ir (mppy) ₃ as a guest material.

"Organic EL device"
Example 8
On the substrate, an anode made of ITO (indium tin oxide), a hole injection layer with a thickness of 30 nm made of PEDOT: PSS, and a second hole with a thickness of 20 nm made of α-NPD represented by the general formula (7). A transport layer, a 10 nm-thick hole transport layer made of the compound represented by the general formula (5), Ir (mppy) _{3 represented} by the general formula (360) as a guest material, and the general material as a host material Using Bepp _{2 represented} by the formula (330), a 35 nm-thick light-emitting layer in which the content of the guest material in the light-emitting layer is 6% by weight, and a 40 nm-thick electron transport composed of TPBI represented by the following general formula (391) A layer, a 1 nm-thick electron injection layer made of a LiF film, and a cathode made of an Al film were sequentially formed by a known method.

Comparative Example 4
An organic EL device of Comparative Example 8 was formed in the same manner as in Example 3 except that the material of the hole transport layer was changed to NPAPF represented by the general formula (9).

Comparative Example 5
An organic EL device of Comparative Example 4 was formed in the same manner as in Example 8, except that the material of the hole transport layer was changed to SPIRO-TTB represented by the general formula (10).

About the organic EL element of obtained Example 8, the comparative example 4, and the comparative example 5, the element characteristic was investigated. Table 4 shows the voltage, device efficiency, and device life results for a current density of 1.0 (mA / cm ² ).

As shown in the figure, an organic EL device (Example 8) having a hole transport layer composed of the compound represented by the general formula (5) and a comparative example 4 having a hole transport layer composed of NPAPF are compared. It can be seen that the device of Example 8 is greatly improved in any of device efficiency and device life. Further, even when Example 8 and Comparative Example 5 in which the central skeleton is common to spirobifluorene are compared, the device of Example 8 using the compound of the present invention is greatly improved in both device efficiency and device life. The result is improved. This is because Example 8 has appropriate electrical characteristics as a hole transporting material, and has high thermal stability and electrical stability in addition to high band gap energy and T ₁ energy. Conceivable.

Claims (11)

A compound represented by the following general formula (1).
X ^{1 to} X ⁴ are each independently selected from hydrogen or any one of the following general formula (2), and at least one of X ¹ and X ³ is the following general formula (2), and X ² and At least one of X ⁴ is the following general formula (2).
Here, R ^{1 to} R ⁶ are each independently selected from any one of hydrogen, an alkyl group, and a halogen group, and each may be independently present in a singular or plural number. The groups may be the same or different from each other.
Y represents an aromatic cyclic group having no substituent and having a substituent of any one of a linear, branched, or cyclic alkyl group, a halogen group, an amino group, a nitro group, and a cyano group. In the general formula (1), X ^{1 to} X ⁴ are each independently selected from hydrogen, the following general formula (3), or the following general formula (4), and among X ¹ and X ³ At least one is the following general formula (3) or the following general formula (4), and at least one of X ² and X ⁴ is the following general formula (3) or the following general formula (4). Compound described in 1.
Here, R ^{1 to} R ⁶ are each independently selected from any one of hydrogen, an alkyl group, and a halogen group, and each may be independently present in a singular or plural number. The groups may be the same or different from each other.
Y represents an aromatic cyclic group which may have a substituent. The compound according to claim 1 , wherein Y is a phenyl group. The compound according to any one of claims 1 to 3 , wherein R ^{1 to} R ⁶ are hydrogen. A compound represented by the following chemical formula (5).
A compound represented by the following chemical formula (6).
An organic electroluminescence device comprising an electrode, an anode, and a layer formed of an organic compound between the two electrodes,
The organic electroluminescent element characterized by including the compound as described in any one of Claims 1-6 in the layer formed with the said organic compound. An organic electroluminescence device containing a charge transport material between an anode, a cathode, and both of these electrodes,
An organic electroluminescence device comprising the compound according to any one of claims 1 to 6 in the charge transport material. An organic electroluminescence device containing a positive hole transport layer between an anode, a cathode, and both of these electrodes,
The organic electroluminescent element characterized by including the compound as described in any one of Claims 1-6 in the said positive hole transport layer. An organic electroluminescence device containing a light emitting layer and a hole transport layer between an anode, a cathode, and both of these electrodes,
The light emitting layer includes a host material and a guest material made of a light emitting material,
The host material is an electron transporting material or a charge transporting material of both electrons and holes,
The organic electroluminescent element characterized by including the compound as described in any one of Claims 1-6 in the said positive hole transport layer. The organic electroluminescence device according to claim 10 , wherein the guest material is a phosphorescent material.