JP6524578B2 - Compound and organic electroluminescent device - Google Patents

Description

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

Organic electroluminescent (hereinafter referred to as organic EL) elements are self-luminous type, wide viewing angle, excellent visibility, low voltage drive, surface emission, thin and lightweight, multicolor display possible, etc. Can be used as a display or lighting.
The organic EL device is usually configured 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 on this transparent substrate in this positional relationship.
In the light emission of the organic EL device, (1) holes and electrons are injected from the electrode, (2) the injected holes and electrons are transported, and (3) holes and electrons are recombined in the light emitting layer, (4) The light emitting material is generated through the process of forming an electronically excited state and (5) emitting light from the electronically excited state.

In order to obtain high luminous efficiency (external quantum efficiency) in the organic EL element, it is necessary to efficiently carry out charge recombination in the process of (3) above, and for that purpose, the above (1) (2) The injection and transport of charge in the process of
That is, in order to improve the recombination efficiency, it is necessary to adjust the transport balance of holes and electrons, but to adjust the transport balance of holes and electrons, it is necessary to use positive hole injection materials and positive hole transport materials. Many factors need to be considered, such as hole mobility, electron injection materials, electron mobility of electron transport materials, charge injection barriers at layer interfaces, and the thickness of each film.

However, the hole and electron transportability of the material itself differs depending on the material, and a charge injection barrier occurs at the interface of layers formed of different materials, so that holes and electrons are rebalanced in a well-balanced manner in the light emitting layer. It is not easy to combine. Therefore, there is used a method of providing a layer that blocks excess charge that would flow to the counter electrode without recombination to confine the charge in the light emitting layer to enhance recombination efficiency. In general, the hole transport layer and the electron transport layer often play the role of blocking the charge that has flowed out and confining the charge in the light emitting layer.

The properties required for the hole transport material used to enhance the recombination efficiency of the organic EL element are high hole transportability and low electron transportability, as well as band gap, ionization potential (IP), electron affinity It is important that the value of (Ea) has an appropriate value. The ionization potential is desirably 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, which can reduce the hole injection barrier to the light emitting layer. It is desirable that the electron affinity be greater than the electron affinity of the light-emitting material, whereby an electron blocking effect can be obtained. In addition, the HOMO level is used almost synonymous with the ionization potential (IP) which is one of the parameter | index of charge injection, and the word of the LUMO level may be used substantially synonymous with electron affinity (Ea).
An example in which the external quantum efficiency of the organic EL device and the device lifetime change by changing the hole transport material has been reported (Non-Patent Document 1).

Appl. Phys. Lett. 103, 143306 (2013)

An object of the present invention is to provide a novel compound which has a large band gap, T1 energy, is excellent in electrical stability and thermal stability, and can be used also for a hole transport layer of an organic EL device. Furthermore, it is an object of the present invention to provide an organic EL device having a long life and high luminous efficiency, which is provided with a hole transport layer containing the above-mentioned compound.

As a result of various studies, the inventors succeeded in synthesizing a compound represented by the following general formula (1), and the compound is extremely useful as a hole transport material of an organic EL device, and the efficiency of the organic EL device is enhanced And found that it contributes to prolonging the life.

That is, the present invention relates to the following.
(A) The compound shown by following General formula (1).

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

Here, R 1 to R 6 are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present in a single or plural number, When there exist two or more, they may be the same or different from each other.
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, or the following general formula (3), or the following general formula (4), and at least of X 1 to X 4 The compound as described in (a) whose one is following General formula (3) or following General formula (4).

Here, R 1 to R 6 are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present in a single or plural number, When there exist two or more, they may be the same or different from each other.
Y represents an aromatic cyclic group which may have a substituent.
(C) The compound according to (a) or (b), wherein X1 to X4 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 X3 and X4 are hydrogen.
(F) The compound according to (a) or (b), wherein X2 and X4 are hydrogen.
(G) The compound according to (a) or (b), wherein X2, X3 and X4 are hydrogen.
(H) The bonding position of X1 to X4 is respectively at the 2nd, 7th, 2 'and 7' positions of the spirobifluorene skeleton, according to any one of (a) to (g) Compound described.
(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 R1 to R6 are hydrogen.
(K) The compound shown by following Chemical formula (5).

(L) The compound shown by following Chemical formula (6).

(M) The compound shown by following Chemical formula (7).

(N) A compound represented by the following chemical formula (8).

(O) An organic electroluminescent device comprising an electrode, an anode, and a layer formed of an organic compound between the both electrodes,
An organic electroluminescent device comprising the layer according to any one of (a) to (n) in a layer formed of the organic compound.
(P) An organic electroluminescent device comprising a charge transport material between an anode, a cathode, and both electrodes thereof,
An organic electroluminescent device comprising the charge transport material according to any one of (a) to (n).
(Q) An organic electroluminescent device comprising an anode, a cathode, and a hole transport layer between the both electrodes,
An organic electroluminescent device comprising the compound according to any one of (a) to (n) in the hole transport layer.
(R) An organic electroluminescent device comprising an anode, a cathode, and a light emitting layer and a hole transport layer between the both 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 an electron and hole charge transporting material,
An organic electroluminescent device comprising the compound according to any one of (a) to (n) in the hole transport layer.
(S) The organic electroluminescent device according to (r), wherein the guest material is a phosphorescent material.

The compound of the present invention can also be suitably used as a hole transport material of an organic EL element, and when the compound of the present invention is used for a hole transport layer, a highly efficient and long-lived organic EL element can be obtained it can.

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

The hole transport material of the organic EL element is positive in addition to having charge transport properties such as high hole transportability and low electron transportability from the viewpoint of enhancing charge recombination efficiency and the like in the light emitting layer. Materials with high band gap and appropriate HOMO and LUMO levels from the viewpoint of enhancing hole injection and electron blocking characteristics, and materials with high electrical stability and thermal stability from the viewpoint of prolonging the life. It is ideal to have.

In the compound of the present invention, the collapse of the planarity of the molecule by the central skeleton consisting of spirobifluorene is considered to contribute to the expansion of the band gap. However, there is also a demerit that, if the planarity of the molecule is broken, the electrical characteristics usually deteriorate. Nevertheless, it is possible that the compounds of the present invention not only have adequate HOMO, LUMO levels, but also high electrical stability and thermal stability, while having a large band gap. It can be considered as a synergistic effect by having an aminodibenzofuran skeleton in addition to the spirobifluorene skeleton inside.

Furthermore, the inventors note that the T1 energy of the host material needs to be larger than the T1 energy of the guest material to prevent reverse energy transfer in the light emitting layer, and the decrease in efficiency due to this reverse energy transfer is The phenomenon 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 above-described reverse energy transfer, it is considered desirable that the T1 energy of the hole transport material be larger than that of the light emitting material.
In this respect, the compound of the present invention has a large T1 energy as compared with α-NPD, which is a general hole transport material, so that the efficiency is enhanced in various colors, particularly in green to red organic EL elements. Can be estimated to contribute to prolonging the life.

The present invention relates to the following general formula (1)

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

Here, R 1 to R 6 are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present in a single or plural number, When there exist two or more, they may be the same or different from each other.
Y represents an aromatic cyclic group which may have a substituent.
Relating to the compound represented by
Or X 1 to X 4 in the general formula (1) are each independently selected from hydrogen, or the following general formula (3), or the following general formula (4), and at least one of X 1 to X 4 Is the following general formula (3), or the following general formula (4)

Here, R 1 to R 6 are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present in a single or plural number, When there exist two or more, they may be the same or different from each other.
Y represents an aromatic cyclic group which may have a substituent.
Relating to the compound represented by

R1 to R6 in the above general formulas (1) to (4) are selected from the viewpoints of improvement of film quality after film formation, improvement of electrical stability, improvement of thermal stability, and ease of synthesis and purification of compounds .

Each of R 1 to R 6 is independently selected from hydrogen, an alkyl group which may have a substituent, or a halogen group. The substituent of the alkyl group which may have a substituent in R1 to R6 is selected from any of an alkyl group, an alkoxy group, and a halogen group.

The alkyl group which may have a substituent in R1 to R6 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 property at the time of producing an organic EL element, and the like, 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 a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group And tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl. The cyclic alkyl group preferably has 3 to 18 carbon atoms, and preferably 3 to 8 carbon atoms from the viewpoint of glass transition temperature, steric hindrance, and the like. The cyclic alkyl group is, for example, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, cycloundecyl group, cyclododecyl group, cyclotridecyl group, cyclo Examples thereof include cycloalkyl groups such as tetradecyl group, cycloheptadecyl group and cyclohexyl group, and polycyclic alkyl groups such as bicycloalkyl group and tricycloalkyl group.

The substituents of the alkyl group which may have a substituent in R 1 to R 6 may be substituted by two or more, and each may be different.
The alkyl group selected as the substituent of the alkyl group which may have a substituent is the total of the alkyl group which becomes the main chain and the alkyl group which is the substituent from the viewpoint of film forming property at the time of producing the organic EL device. The number of carbon atoms is preferably 1 to 18, and the total number of carbon atoms is more preferably 1 to 6 from the viewpoint of glass transition temperature, steric hindrance and the like.

When an alkyl group is selected as a substituent of the alkyl group which may have a substituent, 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-propyl heptyl group, 1-n-butyl heptyl group, 1-n-pentyl heptyl group, 1-n-heptyl heptyl 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 group Octyl group, 1-n-octyl octyl group, 1-methyl nonyl group, 1-ethyl nonyl group, 1-n-propyl nonyl group, 1-n-butyl nonyl group, 1-n-pentyl nonyl group, 1-n-hexyl nonyl group Group, 1-n-heptyl nonyl group, 1-n-octyl nonyl group, 1-n-nonyl nonyl group, 1-methyl decyl group, iso-propyl group, t-butyl group, 2-methyl butyl group, 2-ethyl butyl group, 2 -N-propylpentyl group, 2-methylhexyl group, 2-ethylhexyl group, 2-n-propylhexyl group, 2-n-butylhexyl group, 2-methylheptene group Group, 2-ethylheptyl group, 2-n-propyl heptyl group, 2-n-butyl heptyl group, 2-n-pentyl heptyl group, 2-methyloctyl group, 2-ethyloctyl group, 2-n-propyl group Octyl, 2-n-butyloctyl, 2-n-pentyloctyl, 2-n-hexyloctyl, 2-methylnonyl, 2-ethylnonyl, 2-n-propylnonyl, 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- Methyl butyl group, 3-methyl pentyl group, 3-ethyl pentyl group, 4-methyl pentyl group, 4-ethyl hexyl group, 2,3-dimethyl pentyl group, 2,4- dimethyl pen And 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. may be mentioned.

The alkoxy group selected as a substituent of the alkyl group which may have a substituent is preferably an alkyl group and its substituent from the viewpoint of solubility in a general-purpose organic solvent, film forming property at the time of preparation of an organic EL device, etc. It is preferable that the carbon number which totaled the alkoxy group which is these becomes 1-18, and it is more preferable that the total carbon number becomes 1-6 from a viewpoint of a glass transition temperature, a steric hindrance, etc.

Examples of the halogen group selected as the substituent of the alkyl group which may have a substituent include a fluorine group, a chloro group, a bromo group and an iodine group, and among them, electrical and thermal stability and easiness of synthesis From the viewpoint of height, a fluorine group is preferred.

Here, for R5 and R6, as described above, hydrogen, an alkyl group or a halogen group is selected, but electrical stability, thermal stability, film forming property, ease of synthesis and purification, etc. Judging, hydrogen or methyl is most preferred. In addition, when a methyl group is selected, substitution at the 2-position or 4-position which is a reaction point of dibenzofuran is considered to increase the electrical stability, which is preferable.

In the general formulas (2) to (4), Y is the HOMO level, LUMO level, electrical effect such as band gap of the compound, and thermal stability such as melting point, glass transition temperature, and steric hindrance effect. It is chosen from the point of view.

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 be substituted and 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 aromatic hydrocarbon ring groups of 6π electron system, 10π electron system, 12π electron system, and 14π electron system. And phenyl, biphenyl, naphthyl, terphenyl, anthryl, azulenyl, fluorenyl, pyrenyl, phenanthryl, naphthlyl and the like, among which phenyl group and naphthyl are particularly preferred from the viewpoint of obtaining appropriate electrical effects and thermal stability. And a biphenyl group is preferred.
Further, in the case of a biphenyl group, when an alkyl group such as a methyl group is introduced at a position corresponding to the ortho position of the bonding position of phenyls among the biphenyls, the biphenyl skeleton is twisted due to steric hindrance and the spread of π conjugated system is suppressed. In particular, 2,2′-dimethyl-1,1′-biphenyl is preferable because it is possible to obtain an electrical effect.

Examples of the aromatic heterocyclic group represented by Y include 6π electron system, 10π electron system, 12π electron system, 14π electron system aromatic heterocyclic group, and specific examples thereof include thienyl, furyl, pyrrolyl, thiazolyl, Isothiazolyl, pyrazolyl, oxazolyl, isooxazolyl, pyridyl, pyridazyl, oxadiazolyl, imidazolyl, triazyl, thiadiazolyl, benzothiazolyl, benzoimidazolyl, 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 , Phenanth Lil, Fenajiriru, Fenikisajiriru, and the like. Among them, dibenzothiophenyl is particularly preferable from the viewpoint of obtaining an appropriate electrical effect.

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

X1 to X4 in the general formula (1) are each independently selected from hydrogen, or any of the following general formula (2), the following general formula (3), or the following general formula (4), and X1 to X4 Among them, at least one is any of the following general formula (2), the following general formula (3), or the following general formula (4). Among them, from the viewpoint of easiness of synthesis, among X1 to X4, X3 and X4 are preferably hydrogen, or X2 and X4 are preferably hydrogen. Moreover, it is preferable that X1-X4 is General formula (3) or General formula (4) from a viewpoint of electrical stability and the easiness of synthetic | combination. Furthermore, from the viewpoint of easiness of synthesis, it is preferable that the bonding position of X1 to X4 is respectively at the 2-position, 7-position, 2'-position and 7'-position of the spirobifluorene skeleton.

Below, a more specific compound is illustrated.
X1 to X4 in the general formula (1) are represented by the general formula (2), and are substituted at one or more at any position of the spirofluorene skeleton. For example, it is represented by the following general formula.

X1 to X4 in the general formula (1) are represented by the general formula (2), and further, the general formula (2) is represented by the following general formula. The bond position with spirofluorene is indicated by a broken line.

The substituent represented by the general formula (2-1) is substituted at the 2-position, 2, 2'-position, 2, 7-position, 2, 2'-, 7-position, 2, 2 ', 7, 7'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-2) is substituted at the 2-position, 2, 2'-position, 2, 7-position, 2, 2'-, 7-position, 2, 2 ', 7, 7'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-3) is substituted at the 2-position, 2, 2'-position, 2, 7-position, 2, 2'-, 7-position, 2, 2 ', 7, 7'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-4) is substituted at position 2, 2, 2 ', 2, 7, 2, 2', 7 and 2, 2 ', 7, 7' of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-1) is substituted at the 3-position, the 3,3'-position, the 3,6-position, the 3,3 ', 6-position, the 3,3', 6,6'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-2) is substituted at the 3-position, the 3,3'-position, the 3,6-position, the 3,3 ', 6-position, the 3,3', 6,6'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-3) is substituted at the 3-position, the 3,3'-position, the 3,6-position, the 3,3 ', 6-position, the 3,3', 6,6'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

The substituent represented by the general formula (2-4) is substituted at the 3-position, the 3,3'-position, the 3,6-position, the 3,3 ', 6-position, the 3,3', 6,6'-position of spirofluorene The chemical formula in this case is shown by the following general formula.

When the substituent represented by the general formula (2-1) (2-2) (2-3) (2-4) is substituted at the 4-position and the 4,4 'position of spirofluorene, the chemical formula is the following general formula Indicated.

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

(About composition)
A representative synthetic procedure for the compounds of the present invention is described.
A representative synthetic method of the compound represented by the following general formula (9) will be described.

(9)

The compound represented by the general formula (9) is obtained by halogenating a dibenzofuran derivative using a general halogenation reaction as shown in the following reaction formula (10), and a halogenated dibenzofuran derivative and an aromatic carbonized compound having an amino group. It is synthesized by performing an N-arylation reaction with hydrogen.

(10)

The halogenation reaction includes, for example, a method of directly reacting halogen such as bromine and iodine in the presence of a catalyst, and a method of using a halogenating agent. The halogenating agent is a chlorinating agent, a brominating agent, or an iodizing agent. 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.

Halogenated dibenzofurans having different substitution positions of halogen can be synthesized, for example, by the method shown below.

In order to obtain a compound in which the 4-position of dibenzofuran is halogenated, for example, the method shown in the following reaction formula (11) can be mentioned.

(11)

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

In order to obtain a compound in which the 2-position of dibenzofuran is halogenated, for example, the method shown in the following reaction formula (12) can be mentioned.

(12)

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

As shown in the following reaction formula (13), a halogenated dibenzofuran and an aromatic cyclic group into which an amino group has been introduced are, for example, Buchwald-Hartwig reaction (eg, Org. Synth., 2002, 78, 23), The compound can be synthesized by performing an N-arylation reaction to which Ullmann reaction (eg, Angew. Chem., Int. Ed. 2003, 42, 5400) or the like is applied.

(13)

Incidentally, as shown in the following reaction formula (14), even if N-arylation is carried out using a dibenzofuran derivative into which an amino group is introduced and a halogenated aromatic cyclic group, the above general formula (13) The compounds of) can be synthesized analogously.

(14)

As shown in the following reaction formula (15), an alkyl group etc. can be introduced into dibenzofuran if dibenzofuran halogenated at an arbitrary place and, for example, an alkyl Grignard reagent etc. are used.

(15)

As shown in the following reaction formula (16), it is also possible to introduce an aromatic cyclic group into dibenzofuran if Suzuki coupling reaction (for example, Chem. Rev., 1995, 95, 2457) or the like is used. Further, as the boronic acid derivative, Ra can be selected from any boronic acid derivative such as hydrogen, methyl, isopropyl and the like as needed.

(16)

A dibenzofuran derivative having a substituent R introduced and represented by the following general formula (17) can also be synthesized by applying the above reaction.

(17)

For example, the compound represented by the above general formula (17) can be synthesized by the method represented by the following reaction formula (18).

(18)

In order to introduce the spirobifluorene of the central skeleton in the compound of the present invention, for example, the compounds represented by the following general formulas (19) and (20) can be used as an intermediate.

As shown in the following reaction formula (21), in general halogenation, the 2-position, 2'-position, 7-position and 7'-position of spirofluorene are preferentially halogenated.

(21)

However, after the 2-position of spirofluorene is halogenated, which position among the 2'-position, the 7-position and the 7'-position is preferentially halogenated depends on the reaction conditions.
The halogenation reaction includes, for example, a method of directly reacting halogen such as bromine and iodine in the presence of a catalyst, and a method of using a halogenating agent. The halogenating agent is a chlorinating agent, a brominating agent, or an iodizing agent. 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. The halogenated spirofluorene can also be synthesized by using the method shown in the following reaction formula (23), to which the method described in Chem.

(22)

In addition, spirofluorenes having different substitution positions of halogen can be synthesized by using the method described above. For example, the 2,7-halogenated spirofluorene can be synthesized by the method shown in the following reaction formula (23).

(23)

The spirofluorene skeleton into which a substituent is introduced can also be synthesized by a method shown in the following reaction formula (24) to which the above reaction formula is applied.

(24)

The synthesis of 2,2'-halogenated spirofluorene is described, for example, in Chem. Rev. 2007, 107, 1011 can be used, and the method shown in the following reaction formula (25) can be used.

(25)

In addition, synthesis of 4,4‘-halogenated spirofluorene is described, for example, in Org. Lett. The method shown in the following reaction formula (26), to which the method described in J. Chem.

(26)

Furthermore, a substituent can also be introduced into spirofluorene by the method shown in the following reaction formula (27).

(27)

Furthermore, Chem. Rev. 2007, 107, 1011, various spirofluorene derivatives can be synthesized.
As shown in the following reaction formulas (28) and (29), an N-arylation reaction of the general formula (17) and the general formula (20) or (21) is carried out to obtain the following general formula (28) Or the compounds of the present invention shown in (29) can be synthesized.

(28)

(29)

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

The measurement of the molecular weight of a compound can be performed by mass spectrometry (MS). Mass spectrometry is performed by applying a high voltage in vacuum to the sample introduced from the sample introduction part to ionize the sample, separating ions according to the mass-to-charge ratio, and detecting in the detection part .
The sample introduction unit can be directly connected to gas chromatography (GC / MS), high performance liquid chromatography (LC / MS), capillary electrophoresis (CE / MS), and it measures MS and also measures purity. be able to. In addition, a direct injection method (DI / MS) which directly ionizes a sample may also be adopted.
Various ionization schemes are adopted for the ion source. For example, electron ionization (EI), fast atom bombardment (FAB), electrospray ionization (ESI), inductively coupled plasma (ICP), etc. may be mentioned.

Nuclear magnetic resonance spectrum (NMR) can be used for compound identification. In NMR measurement, information on chemical shift and coupling can be known according to the bonding state of atoms and the like, so that a spectrum unique to a compound can be obtained and a compound can be identified. The measurement is performed by dissolving a small amount of sample in a heavy solvent.

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

By measuring the UV-visible absorption spectrum (UV / VIS), the fluorescence spectrum (PL) and the phosphorescence spectrum of the compound, it is possible not only to know the UV absorption wavelength, the fluorescence wavelength and the phosphorescence wavelength specific to the compound but also the band gap of the compound , Information such as fluorescence quantum yield and T1 energy can be known.

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

(About organic EL element)
The organic EL device of the present invention is characterized by using the compound of the present invention as a hole transport material.

Generally, in an organic EL device, 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 arranged on a substrate in this positional relationship. It is laminated and configured.
The organic EL elements do not have to be entirely formed of an organic substance, and an inorganic material may be used for an electrode, a hole injection layer, an electron injection layer, and the like.
Further, among the layers forming the organic EL element, one of the hole injection layer, the electron transport layer, and the electron injection layer may be omitted.
The organic EL element is classified into a bottom emission type element for extracting light from the substrate side and a top emission type for extracting light from the side opposite to the substrate, and either type can be adopted in the organic EL element of the present invention.

The material used for the substrate may be different between the top emission type and the bottom emission type. A transparent substrate is used for the bottom emission device. 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 glasses such as quartz glass, soda glass, pyrex and the like can be used. In addition, various plastic substrates such as polycarbonate, polyacrylate and polyethylene terephthalate can also be used. Furthermore, two or more of these can be used in combination.

In general, a transparent conductive material is used for the anode of the bottom emission device. In the top emission type, although there is no particular limitation, reflective electrodes 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, as the anode, materials that function as anodes, such as various metal materials having a relatively large work function, various alloys, etc., are used. For example, gold, copper iodide, tin oxide, aluminum-doped zinc oxide (ZnO: Al), indium tin oxide (ITO), indium zinc oxide (IZO), fluorine tin oxide (FTO) and the like can be mentioned. 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 relationship between the work function of the anode and the IP of the hole transport layer, charge transport characteristics, and the like. For example, poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS), copper phthalocyanine (CuPc), molybdenum oxide (MoOx), vanadium oxide (V2O5) and the like can be mentioned. Various organic compounds and inorganic compounds can be selected, regardless of whether they are low molecular weight or high molecular weight compounds, as long as they have appropriate IP and charge transport properties. In addition, two or more of these materials can be used in combination.

The compound of the present invention can be used in the hole transport layer. The compound has a wide band gap, appropriate HOMO and LUMO levels, and is excellent in electrical stability and thermal stability, by having a spirofluorene central skeleton and an aminodibenzofuran skeleton. Accordingly, the charge recombination efficiency in the light emitting layer can be enhanced, and a long-life organic EL element can be realized with higher light emission efficiency, which is preferable.

The compound of the present invention may be used alone, or may be used by mixing one or two or more existing hole transporting materials, or may be used by laminating one or two or more layers. . Examples of the hole transporting material include compounds such as α-NPD.

For the light emitting layer, a fluorescent material or a phosphorescent material can be used. A light emitting material can also be used by including 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. In addition, since the hole transporting material of the present invention is also excellent in electron blocking performance, an electron transporting material can also be used as a host material.

When a phosphorescent material is selected as the guest material, it is preferable to select the host material such that the T1 energy of the host material is higher than the T1 energy of the guest material. In addition, since the compound of the present invention has excellent electron blocking performance, a compound having electron transportability such as Bepp 2 or PIC-TRZ described below can also be used as a host material.

In order for the light emitting material 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. When the guest material is a phosphorescent material, it is preferable that the T1 energy of the host material be larger than the T1 energy of the guest material.

The light emitting material is not particularly limited, but is selected from a fluorescent material, a phosphorescent material and the like, and examples thereof include Ir (mPPy) 3 shown below.

As a material used for an electron carrying layer, TPBI etc. which are shown below can be used, for example. If 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, and further from the electron transport layer The electron injection barrier to the light emitting layer can be relaxed. In addition, when the material has an appropriate HOMO level, it blocks holes that flow out to the counter electrode without recombination in the light emitting layer, confines holes in the light emitting layer, and enhances recombination efficiency in the light emitting layer. be able to. However, if the electron injection barrier is not a problem, and furthermore, the electron transporting ability 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 in view of the work function of the cathode and the LUMO level of the electron transport layer. When the electron transporting 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 injecting 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 may be used in addition to alkali metals and alkaline earth metals. be able to.

The cathode of the organic EL element plays a role of injecting electrons into the electron injecting layer or the electron transporting layer. For the cathode, various metal materials having a relatively small work function, various alloys, and the like that function as a cathode 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 mentioned.
In the case of employing the bottom emission method, an opaque electrode made of metal can be used as the cathode. The cathode can also be used as a reflective electrode.
When the top emission system is adopted, a transparent electrode such as ITO or IZO can be used as the cathode. Here, since ITO has a large work function, in addition to the difficulty in electron injection, sputtering or ion beam evaporation is used to form an ITO film, but it can be used as an electron transport layer or the like during film formation. It can cause damage. Therefore, in order to improve electron injection and to 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 the ITO.

(Synthesis of intermediates)
The compound represented by the following chemical formula (30) was synthesized by the synthetic route shown below.

(30)

Under an argon atmosphere, 33.6 g (0.2 mol) of dibenzofuran and 200 mL of dehydrated diethyl ether were charged in a 500 mL Schlenk tube equipped with a stirrer, and the reaction solution was cooled to 0 ° C. under ice cooling. To this was added dropwise 138 mL (0.22 mol) of a 1.6 M n-butyllithium / hexane solution, followed by reaction under reflux for 16 hours to anionize the 4-position of dibenzofuran.
Furthermore, after cooling the anionization thing of dibenzo furan to -8 ° C, the powder of 50.8 g (0.2M) of iodine was added here, and it stirred for 15 hours, returning to room temperature gradually.
The reaction mixture was poured into water and extracted with diethyl ether, and the obtained organic layer was washed with water and dried over anhydrous sodium sulfate. Then, after the solvent was distilled off, the obtained residue was recrystallized with hexane.
Through the above steps, the desired product was obtained in a yield of 24.8 g and a yield of 42%. The identification of the compound was performed by the molecular ion peak (M + 294) corresponding to the target substance in 1 H-NMR and mass spectrometry.

1 H-NMR (DMSO-d6) δ 7.23 (t, J = 7.8 Hz, 1 H), 7.45 (t, J = 6.8 Hz, 1 H), 7.58 (t, J = 7.4 Hz, 1H), 7.80 (d, J = 8.2 Hz), 7.91 (dd, J = 7.8 Hz, 1.4 Hz, 1 H), 8.17 (d, J = 8.7 Hz, 2 H)

The compound shown by following Chemical formula (31) was synthesize | combined by the method shown below.
(31)

In an argon atmosphere, in a 300 mL Schlenk tube equipped with a stirrer, 15 g (51.0 mmol) of 4-iododibenzofuran, 4.83 g (52.0 mM) of aniline, 7.14 g (63.8 mmol) of potassium-tert-butoxide, Pd2 (Dba) 3 0.47 g (0.51 mmol) and 80 mL of dehydrated toluene were stored and degassed. Thereafter, 0.1 g (0.51 mmol) of tri-tert-butylphosphine was added, the solution was sealed, and stirred at 85 ° C. for 28 hours. Thereafter, the reaction vessel was allowed to cool to around room temperature, the lid was opened, and water (150 mL) was put therein. The contents were transferred to a separating funnel, and after separating the organic layer and the aqueous layer, the aqueous layer was removed and the organic phase was further washed with water. The organic layer was dried over sodium sulfate. Thereafter, sodium sulfate was removed by filtration and the organic layer was concentrated. The concentrated mixture thus obtained was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the desired target compound (yield 6.26 g, 47.4%).

1 H-NMR (DMSO-d6) δ: 6.85 (t, J = 7.3 Hz, 1 H), 7.09 (d, J = 7.4 Hz, 2 H), 7.22-7.35 (m, m) 4H), 7.41 (t, J = 7.4 Hz, 1 H), 7.52 (dt, J = 1.4 Hz, 7.4 Hz, 1 H), 7.69 (d, J = 8.7 Hz, 2 H) ), 8.14 (d, J = 6.9 Hz, 1 H), 8. 38 (s, 1 H)

The intermediate shown in the following chemical formula (32) was synthesized by the synthetic route shown below.

(32)
Dibenzofuran (3.36 g, 20 mmol), NBS (3.92 g, 22 mmol), zirconium chloride (0.10 g, 0.44 mmol), and DMF (40 mL) in a 100 mL Schlenk tube equipped with a stir bar and purged with argon. In addition, it was stirred at 70 ° C. for 18 hours. The reaction solution was added to water (200 mL) to precipitate a solid, and the suspension was stirred for 30 minutes. The suspension was filtered and the resulting solid on filter paper was slowly poured into hot water (100 mL) at 90 ° C. The solid on the filter was collected and then dried to obtain 4.1 g of the desired product (yield 83%).
The compounds were identified by MS spectrum and NMR.

1 H-NMR (DMSO-d6) δ 7.44 (t, J = 7.8 Hz, 1 H), 7.57 (t, J = 8.2 Hz, 1 H), 7.66-7.74 (m, 3 H) 8.21 (dd, J = 1.4 Hz, 7.8 Hz, 1 H), 8.45 (d, J = 2.3 Hz, 1 H)

The compound shown by following Chemical formula (33) was synthesize | combined by the method shown below.
(33)

2-Bromodibenzofuran (2.47 g, 10 mmol), aniline (1.12 g, 12 mmol), palladium acetate (90 mg, 0.4 mmol), toluene (50 mL) in a 100 mL Schlenk tube equipped with a stirrer and purged with argon. Tri-t-butylphosphine (81 mg, 0.4 mmol) and t-butoxy potassium (2.24 g, 20 mmol) were added, and after sealing, the mixture was stirred at 100 ° C. for 18 hours. Thereafter, the reaction vessel was allowed to cool to around room temperature, the lid was opened, and water (50 mL) was put therein. The contents were transferred to a separating funnel, and after separating the organic layer and the aqueous layer, the aqueous layer was removed, and the organic layer was further washed with water. The organic layer was dried over sodium sulfate. Thereafter, sodium sulfate was removed by filtration and the organic layer was concentrated. The concentrated mixture thus obtained was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the desired target compound (yield 1.32 g, 51%).
The compounds were identified by MS spectrum and NMR.

1 H-NMR (DMSO-d6) δ: 6.79 (t, J = 7.3 Hz, 1 H), 7.07 (d, J = 7.3 Hz, 2 H), 7.21-7.25 (m, m) 3H), 7.35 (t, J = 7.3 Hz, 1 H), 7.49 (t, J = 7.6 Hz, 1 H), 7.60 (d, J = 9.2 Hz, 1 H), 7. 65 (d, J = 8.2 Hz, 1 H), 7.83 (d, J = 2.3 Hz, 1 H) 8. 10 (d, J = 6.9 Hz, 1 H), 8. 18 (s, 1 H)

Example 1
The compound shown by following Chemical formula (34) was synthesize | combined by the method shown below.

(34)

N-phenyldibenzo [b, d] furan-4-amine (1.15 g, 4.43 mmol), 2,2'-dibromo-9,9'-spiro, in a 100 mL Schlenk tube, equipped with a stirrer and purged with argon. Bifluorene (1.00 g, 2.11 mmol), palladium acetate (40 mg, 0.18 mmol), toluene (40 mL), tri-t-butyl phosphine (36 mg, 0.18 mmol), and t-butoxy potassium (1.0 g) , 8.9 mmol), and after sealing, stirred at 100 ° C. for 20 hours. Thereafter, the reaction vessel was allowed to cool to around room temperature, the lid was opened, and water (30 mL) was put therein. The contents were transferred to a separating funnel, and after separating the organic layer and the aqueous layer, the aqueous layer was removed, and the organic layer was further washed with water. The organic layer was dried over sodium sulfate. Thereafter, sodium sulfate was removed by filtration and the organic layer was concentrated. The concentrated mixture obtained was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the chemical formula (31) (yield: 1.51 g, collection) 86.2%).

The purity measurement by HPLC was performed under the conditions shown below.
Column “InertSustain, 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”

Identification of the compound was carried out by coincidence of the molecular ion peak with the target in MS spectrum and proton NMR.

1 H-NMR (DMSO-d6) δ: 6.38 (d, J = 2.3 Hz, 2H), 6.66 (d, J = 7.8 Hz, 2H), 6.86-6.98 (m, m) 8H), 6.07-7.10 (m, 4H), 7.19 (t, J = 8.2 Hz, 4H), 7.28-7.34 (m, 4H), 7.48-7. 52 (m, 2 H), 7.59 (d, 8.7 Hz, 2 H), 7.67 (d, J = 8.3 Hz, 2 H), 7.76-7.81 (m, 6 H), 8. 00 (d, J = 7.4 Hz, 2 H)

Example 2
The compound shown by following Chemical formula (35) was synthesize | combined by the method shown below.

(35)

N-phenyldibenzo [b, d] thiophene-4-amine (1.09 g, 4.20 mmol), 2,7-dibromo-9,9'-spirobii, provided in a 100 mL Schlenk tube, equipped with a stirrer and purged with argon. Fluorene (0.95 g, 2.0 mmol), Pd2 (dba) 3 or tris (dibenzylideneacetone) palladium (0) (36 mg, 0.04 mmol), toluene (40 mL), tri-t-butylphosphine (8.1 mg) , 0.04 mmol) and potassium t-butoxide (0.56 g, 5.0 mmol), and after sealing, stirred at 100 ° C. for 2 hours. Thereafter, the reaction vessel was allowed to cool to around room temperature, the lid was opened, and water (30 mL) was put therein. The contents were transferred to a separating funnel, and after separating the organic layer and the aqueous layer, the aqueous layer was removed, and the organic layer was further washed with water. The organic layer was dried over sodium sulfate. Thereafter, sodium sulfate was removed by filtration and the organic layer was concentrated. The concentrated mixture obtained was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the above chemical formula (36) (yield: 1.56 g, collection) 94.0%).

The purity measurement by HPLC was performed under the conditions shown below.
Column “InertSustain, 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”

Identification of the compound was carried out by coincidence of the molecular ion peak with the target in MS spectrum and proton NMR.

1 H-NMR (DMSO-d6) δ: 6.06 (d, J = 2.3 Hz, 2 H), 6.66 (d, J = 7.8 Hz, 2 H), 6.80-6.87 (m, 6H), 6.93-7.01 (m, 6H), 7.10 (t, J = 7.8 Hz, 2H), 7.15-7.24 (m, 6H), 7.35-7. 48 (m, 6 H), 7.63 (d, 7.8 Hz, 2 H), 7.81 (t, J = 7.8 Hz, 4 H), 8.05 (d, J = 7.8 Hz, 2 H)

Example 3
The compound shown by following Chemical formula (36) was synthesize | combined by the method shown below.

(36)

N-phenyldibenzo [b, d] thiophene-4-amine (1.40 g, 5.40 mmol), 2,7-dibromo-9,9'-spirobib, in a 100 mL Schlenk tube, equipped with a stir bar and purged with argon. Fluorene (1.10 g, 2.57 mmol), Pd2 (dba) 3 (47 mg, 0.05 mmol), toluene (25 mL), tri-t-butylphosphine (10 mg, 0.05 mmol), and t-butoxy potassium (0 mg) .72 g (6.4 mmol) was added and after sealing, it was stirred at 100.degree. C. for 2 hours. Thereafter, the reaction vessel was allowed to cool to around room temperature, the lid was opened, and water (30 mL) was put therein. The contents were transferred to a separating funnel, and after separating the organic layer and the aqueous layer, the aqueous layer was removed, and the organic layer was further washed with water. The organic layer was dried over sodium sulfate. Thereafter, sodium sulfate was removed by filtration and the organic layer was concentrated. The concentrated mixture obtained was purified by silica gel column chromatography (developing solvent: hexane / dichloromethane = 3/1) to obtain the target compound represented by the above chemical formula (33) (yield: 1.66 g, collection) 77.9%).

The purity measurement by HPLC was performed under the conditions shown below.
Column “InertSustain, 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”

Identification of the compound was carried out by coincidence of the molecular ion peak with the target in MS spectrum and proton NMR.

1 H-NMR (DMSO-d6) δ: 6.23 (d, J = 1.8 Hz, 2 H), 6.83-6.94 (m, 10 H), 7.05 (dd, J = 2.3 Hz, 8.7 Hz, 2 H), 7.1 1 to 7.20 (m, 6 H), 7. 25 (t, J = 7.3 Hz, 2 H), 7. 34 (t, J = 7.3 Hz, 2 H), 7.48-7.55 (m, 4H), 7.65 (d, J = 8.7 Hz, 2 H), 7.73 (q, J = 2.3 Hz, 4 H), 7.78 (d, J = 8.2 Hz, 2 H), 7.97 (d, J = 7.8 Hz, 2 H)

"Organic EL element"
In order to show the usefulness of the developed material, the organic EL element using three types of the following compounds was produced.

Example 4
On the substrate, an anode made of ITO (indium tin oxide), a hole injection layer of 30 nm in thickness made of PEDOT: PSS, a second hole transport layer of 20 nm in thickness made of α-NPD, and the chemical formula (35) (36) Using a hole transport layer having a thickness of 10 nm comprising the compound shown in (37), Ir (mppy) 3 as a guest material, PIC-TRZ as a host material, and the content of the guest material in the light emitting layer A 25 nm-thick light emitting layer with 1% by weight, an electron transporting layer of 35 nm in thickness made of TPBI, an electron injecting layer of 1 nm in thickness made of a LiF film, and a cathode made of an Al film were sequentially formed by a known method.

Comparative Example 1
An organic EL device was formed in the same manner as Example 4, except that the material of the hole transport layer was replaced with SPIRO-TTB or α-NPD represented by the following chemical formula.

The element characteristics of the obtained organic EL elements of Example 4 and Comparative Example 1 were examined. Table 1 shows the voltage at a current density of 1.0 (mA / cm 2), the device efficiency, and the device life results.

As shown in Table 1, an organic EL device having a hole transport layer consisting of a compound represented by the chemical formulas (35), (36), (37) and a Spiro-TTB having a central skeleton common to spirobifluorene are used. When the various characteristics are compared, the device using the compound of the present invention is significantly improved in both the device efficiency and the device life. This is considered to be due to the fact that the compound of the present invention has suitable electrical properties as a hole transporting material, and the band gap energy and the T1 energy are large.

DSC measurement was performed on the compound represented by the chemical formulas (31), (32), and (33) and α-NPD for which the usefulness as a hole transport material was thus confirmed. The results of the glass transition temperature are shown in Table 2.

As shown in Table 2, the compounds represented by the chemical formulas (35), (36), and (37) have high Tg and excellent thermal stability compared to α-NPD which is a general hole transport material. I understand.

Measure the emission spectrum at a low temperature of 77 K using a thin film consisting of a compound represented by the chemical formula (35) and a thin film consisting of α-NPD, using FluoroMax-4 manufactured by HORIBA, and using a 300 nm wavelength excitation light source The T1 energy of each thin film was calculated. The results are shown in Table 3 below.

From the viewpoint of energy confinement, the T1 energy of the hole transport layer material is preferably large. From the results shown in the above figure, the hole transport layer made of the compound according to the present invention has a large triplet energy compared to α-NPD which is a general hole transport material, and the energy confinement of more light emitting materials It becomes possible.

Claims (14)

The compound shown by following General formula (1).
Each of X ^{1 to} X ⁴ independently represents the following general formula (2).
Here, R ^{1 to} R ⁶ are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present alone or in combination. When two or more are present, they 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 X ^{1 to} X ⁴ in the general formula (1) are each independently selected from any of the following general formula (3) or the following general formula (4).
Here, R ^{1 to} R ⁶ are each independently selected from any of hydrogen, an alkyl group which may have a substituent, or a halogen group, and each may be independently present alone or in combination. When two or more are present, they 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 or 2, wherein the bonding position of X ^{1 to} X ⁴ is respectively at position 2, 7 position, 2 'position and 7' position of spirobifluorene skeleton. A compound according to any one of claims 1 to 3 wherein Y is a phenyl group. 5. A compound according to any one of claims 1 to 4 wherein R < ¹ > to R < ⁶ > are hydrogen. The compound shown by following Chemical formula (5).
The compound shown by following Chemical formula (6).
The compound shown by following Chemical formula (7).
The compound shown by following Chemical formula (8).
An organic electroluminescent device comprising an electrode, an anode, and a layer formed of an organic compound between the two electrodes,
An organic electroluminescent device comprising the compound according to any one of claims 1 to 9 in a layer formed of the organic compound. What is claimed is: 1. An organic electroluminescent device comprising a charge transport material between an anode, a cathode, and both electrodes thereof,
An organic electroluminescent device comprising the charge transport material according to any one of claims 1 to 9. What is claimed is: 1. An organic electroluminescent device comprising an anode, a cathode, and a hole transport layer between the both electrodes,
An organic electroluminescent device comprising the compound according to any one of claims 1 to 9 in the hole transport layer. An organic electroluminescent device comprising an anode, a cathode, and a light emitting layer and a hole transport layer between the both 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 an electron and hole charge transporting material,
An organic electroluminescent device comprising the compound according to any one of claims 1 to 9 in the hole transport layer. The organic electroluminescent device according to claim 13, wherein the guest material is a phosphorescent material.