JP6264603B2 - Copper complex and organic electroluminescence device - Google Patents

Description

  The present invention relates to a copper complex and an organic electroluminescence device. More specifically, the present invention relates to a copper complex having improved luminous efficiency.

  An organic EL element (also referred to as “organic electroluminescence element”) using an organic material electroluminescence (hereinafter abbreviated as “EL”) has already been put into practical use as a new light emitting system that enables planar light emission. Technology. Organic EL elements are not only applied to electronic displays but also recently applied to lighting equipment, and their development is expected.

There are two types of organic EL emission methods: “phosphorescence emission” that emits light when returning from the triplet excited state to the ground state and “fluorescence emission” that emits light when returning from the singlet excited state to the ground state. There is.
When an electric field is applied to the organic EL element, holes and electrons are injected from the anode and the cathode, respectively, and recombine in the light emitting layer to generate excitons. At this time, singlet excitons and triplet excitons are generated at a ratio of 25%: 75%. Furthermore, singlet excitons can be converted into triplet excitons by intersystem crossing, so triplet excitons are used. It is known that phosphorescent light emission that yields a theoretically higher internal quantum efficiency (˜100%) than fluorescent light emission.
However, in order to actually obtain high quantum efficiency (hereinafter also referred to as quantum yield) in the phosphorescence emission method, it is necessary to use a complex using a rare metal such as iridium or platinum as a central metal, In addition, there is concern that the reserves of rare metals and the price of the metals themselves will be a major issue in the industry.

On the other hand, various developments have been made to improve the light emission efficiency in the fluorescent light emitting type, and a new movement has recently been made.
For example, Patent Document 1 discloses a phenomenon in which singlet excitons are generated by collision of two triplet excitons (hereinafter referred to as “triplet-triplet annihilation”, hereinafter abbreviated as “TTA” as appropriate. Triplet-Triplet Fusion: Focusing on “TTF”), a technique for efficiently raising the fluorescence emission by efficiently causing TTA is disclosed. This technology improves the power efficiency of fluorescent compounds (hereinafter also referred to as fluorescent materials), up to 2-3 times that of conventional fluorescent compounds, but the theoretical singlet in TTA. Since the exciton generation efficiency is limited to about 40%, there is still a problem of higher emission efficiency than phosphorescence emission.
Furthermore, in recent years, Adachi et al. Have developed a fluorescent compound using a thermally activated delayed fluorescence (also referred to as “thermally activated delayed fluorescence”: hereinafter, abbreviated as “TADF” as appropriate) mechanism. And the possibility of use for organic EL elements has been reported (for example, see Non-Patent Document 1).

  As shown in FIG. 1, the TADF mechanism is a compound having a smaller difference (ΔEst) between the singlet excitation energy level and the triplet excitation energy level (ΔEst (TADF) in FIG. 1) as compared with a normal fluorescent compound. Is a light emission mechanism utilizing a phenomenon in which a reverse intersystem crossing from a triplet exciton to a singlet exciton occurs in a case where is smaller than ΔEst (F). A compound that causes only fluorescence emission that does not cause phosphorescence emission cannot contribute to light emission because triplet excitons generated with a probability of 75% by electric field excitation are deactivated without radiation from the triplet excited state. On the other hand, since the TADF compound has a small ΔEst, the TADF compound transitions to a singlet excited state by thermal energy or the like when driving the organic EL element, and radiation deactivation (“radiation transition” or “radiation deactivation”) from the state to the ground state. It also causes fluorescence emission. If delayed fluorescence due to the TADF mechanism is used, it is considered that 100% internal quantum efficiency is theoretically possible even in fluorescence emission.

Therefore, as a luminescent compound, there is an expectation for research on a copper complex exhibiting delayed fluorescence using copper, which can be obtained at a lower cost than iridium, as a central metal (Patent Documents 1 to 3 and Non-Patent Document 2). ~ 4).
However, the copper complexes described in Patent Documents 1 to 3 and Non-Patent Documents 2 to 4 are considered to have room for improvement from the viewpoint of adaptability to organic EL elements.

International Publication No. 2011/063083 JP 2012-25690 A JP 2011-213643 A

H. Uoyama, et al. , Nature, 2012, 492, 234-238. A. Wada et al. , Chem. Commun. 2012, 48, 5340-5342 M.M. Hashimoto, et al. , J .; Am. Chem. Soc. , 2011, 133, 10348-10351 R. Czerwienec et al. Inorg. Chem. , 2011, 50, 8293-8301

  This invention is made | formed in view of the said problem and the situation, The solution subject is providing the organic electroluminescent element using the novel copper complex which shows delayed fluorescence, and the said copper complex.

As a result of studying the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor has found that a new copper complex can be obtained when the copper complex has a structure represented by the following general formula (2). As a result, the present invention has been achieved.
That is, the said subject which concerns on this invention is solved by the following means.

（一般式（２）中、Ｘは、硫黄原子を表す。Ｌは、アリーレン基を表す。Ｗは、ハロゲン化アルキル基を表す。Ｚ_１〜Ｚ_４は、それぞれ、アルキル基を表し、互いに異なっていてもよい。ｎ１〜ｎ４は、それぞれ０又は１の整数を表す。ｍは、０〜５の整数を表す。） 1. Copper complex you characterized by having a structure represented by the following general formula (2).

(In the general formula (2), X, .L representing the vulcanization Kihara child is .W which represents an arylene group, _.Z 1 to Z ₄ representing an alkyl halide groups each represent an alkyl group, the Ttei and may .n1~n4 different from each other, .m each represents an integer of 0 or 1 represents an integer of 0-5.)

2 . An organic electroluminescence device having at least one light emitting layer sandwiched between an anode and a cathode,
An organic electroluminescence device comprising the light emitting layer containing the copper complex according to item 1.

  By the above means of the present invention, a novel copper complex exhibiting delayed fluorescence and an organic electroluminescence device using the copper complex can be provided.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
In general, a monovalent copper complex exhibits delayed fluorescence, but in order to exhibit particularly high luminous efficiency (delayed fluorescence), it has been found that the structure of the electron orbit of the complex is important. That is, it is important that the trajectory forming the HOMO (highest occupied molecular orbital) and the trajectory forming the LUMO (lowest unoccupied molecular orbital) are substantially separated and exist at relatively close positions.
It is known that such an electronic structure can lower ΔEst, which is the energy difference between singlet energy and triplet energy, and can exhibit high delayed fluorescence. We have found that copper complexes are suitable. A monovalent copper complex has a three-coordinate structure of a neutral ligand and an anionic ligand, and the HOMO level is present in the vicinity of the copper atom due to a strong interaction between the copper atom and the chalcogen atom. It becomes. As a result, the HOMO electron cloud and the LUMO electron cloud can be present at positions close to the extent that they can be moved by hopping while being substantially separated. As a result, it has been found that the copper complex of the present invention exhibits high luminous efficiency (delayed fluorescence) and becomes a useful compound as a luminescent compound for an organic EL device.

Schematic diagram showing energy diagrams of general fluorescent compounds and TADF compounds Schematic of lighting device Schematic diagram of lighting device Crystal structure of copper complex Cu-36 Emission spectrum of copper complex Cu-36 Emission spectrum of copper complex Cu-37 Emission spectrum of copper complex Cu-45

The copper complex of the present invention has a structure represented by the general formula (2) . This feature is technical feature common to the invention according to each claim.

The embodiments of the present invention, one in general formula (1), any of the ligand represented by Y ₁ or Y ₂ preferably contains a coordinating phosphorus atom in the copper metal centers.
This is because a zero-valent (neutral) ligand containing phosphorus can form a stable complex with strong coordinating power to copper, and can have three substituents from the phosphorus atom. This is because the obtained copper complex can have a three-dimensional geometry, and agglomeration that causes a decrease in light emission efficiency in the light emitting layer of the organic EL element can be reduced.

Further, in one general formula (1), ligand represented by Y ₁ and Y _2, may each include a coordinating phosphorus atom in the copper metal centers, preferably.
It is possible to select variously from a relatively high excitation level (S _{1 in the} singlet excited state and T _{1 in the} triplet excited state) to a low one (emission color from short blue to long red). This is because there is a merit that the degree of freedom in selecting the emission color is high.

Further, in one general formula (1), atoms represented by X is, it is a sulfur atom is preferable in order to enhance the effect of the present invention further. This is because the sulfur is particularly high in bonding with Group 11 elements such as copper. From such an effect, the stability of the resulting complex can be increased.

Further, in one general formula (1), the substituent represented by R is preferably a substituted or unsubstituted aromatic ring group. This is because the substituent represented by the above -X-R in the general formula (1) has approximately the HOMO orbital, so that the HOMO orbital is stabilized and the transition probability from the excited state, that is, the luminous efficiency is high. This is because it can be done.

Another aspect general formula represented by structure (1), it is preferable that the a structure represented by the general formula (2). That is, of the structure represented by a general formula (1), it is preferable substituents represented by Y ₁ and Y ₂ is a bidentate ligand which is linked by linking group L. By selecting such a ligand, the rigidity of the structure in the excited state is increased, the deactivation due to thermal vibration in the excited state can be suppressed, and the light emission efficiency can be increased. In addition, HOMO and LUMO are substantially determined from the coordination positions of the bidentate ligand in which the substituents represented by Y ₁ and Y ₂ are linked by the linking group L and the substituent represented by —X—R. Therefore, ΔEst is reduced and delayed fluorescence is easily obtained. In addition, with respect to the emission wavelength, it is also possible to emit high energy light such as blue.

In the general formula (2), each of the substituents represented by Z _{1 to} Z ₄ is preferably an electron donating group. As a result, the LUMO level of the ligand containing phosphorus can be made high, which improves the degree of separation between the HOMO orbital and LUMO orbitals and helps to improve delayed fluorescence. Moreover, it is preferable for obtaining a blue light emitting compound. Examples of the electron donating group include an alkyl group, an amino group, an alkoxy group, a cycloalkyl group, and a phenoxy group.

In the general formula (2), each of the substituents represented by Z _{1 to} Z ₄ is preferably an alkyl group. Thereby, the rigidity of the bidentate ligand can be improved and the expression of delayed fluorescence can be enhanced. Moreover, a highly soluble luminescent compound can be obtained for the organic EL element formed by coating. In addition, as a position which these electron donating substituents substitute, an ortho position and a para position are preferable with respect to the phosphorus atom on a benzene ring, Most preferably, it is an ortho position. A compound having a substituent at the ortho position has the highest rigidity and can enhance the expression of high delayed fluorescence.

  In the general formula (2), the substituent represented by W is preferably an electron withdrawing group in order to further enhance the effect of the present invention. As a result, the energy level of the HOMO orbital formed by the anionic ligand containing chalcogen can be lowered, and the degree of separation between the HOMO orbital and LUMO orbitals is improved, which is useful for improving delayed fluorescence. Moreover, it is preferable for obtaining a blue light emitting compound.

  In the general formula (2), the substituent represented by W is preferably a fluorine-containing substituent in order to further enhance the effects of the present invention. In addition, the fluorine substituent is preferable because it has an effect of preventing the light emitting compound from aggregating in the light emitting layer.

  The organic electroluminescent element of the present invention is an organic electroluminescent element having at least one light emitting layer sandwiched between an anode and a cathode, and preferably contains a copper complex in the light emitting layer. As a result, an organic electroluminescence element having high light emission can be obtained.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.
Before going into this discussion, an organic EL light emitting system and a light emitting compound related to the technical idea of the present invention will be described.

<Light emitting method of organic EL>
There are two types of organic EL emission methods: “phosphorescence emission” that emits light when returning from the triplet excited state to the ground state, and “fluorescence emission” that emits light when returning from the singlet excited state to the ground state. is there.
When excited by an electric field such as an organic EL, triplet excitons are generated with a probability of 75% and singlet excitons are generated with a probability of 25%. Therefore, phosphorescence is more efficient than fluorescence. This is an excellent method for realizing low power consumption.
On the other hand, in the fluorescence emission, the triplet excitons, which are generated with a probability of 75% and the exciton energy is likely to become heat due to non-radiation deactivation, are present at high density. A system using a TTA (triplet-triplet annealing: also abbreviated as “TTF”) mechanism that generates singlet excitons from excitons to improve luminous efficiency has been found.

  Furthermore, in recent years, the discovery of Adachi et al. Has reduced the energy gap between the singlet excited state and the triplet excited state. Reverse intersystem crossing from the singlet excited state to the singlet excited state, and as a result, a phenomenon that enables nearly 100% fluorescence emission (also referred to as thermally excited delayed fluorescence or thermally excited delayed fluorescence: “TADF”) And a fluorescent substance that makes this possible have been found (for example, see Non-Patent Document 1).

<Phosphorescent compound>
As described above, phosphorescence emission is theoretically 3 times more advantageous than fluorescence emission in terms of light emission efficiency, but energy deactivation (= phosphorescence emission) from triplet excited state to singlet ground state is a forbidden transition. Similarly, since the intersystem crossing from the singlet excited state to the triplet excited state is also a forbidden transition, the rate constant is usually small. That is, since the transition is difficult to occur, the exciton lifetime is increased from millisecond to second order, and it is difficult to obtain desired light emission.
However, when a complex using a heavy metal such as iridium or platinum emits light, the rate constant of the forbidden transition increases by 3 digits or more due to the heavy atom effect of the central metal. % Phosphorescence quantum yield can be obtained.
However, in order to obtain such ideal light emission, it is necessary to use a rare metal called a white metal such as iridium, palladium, or platinum, which is a rare metal. The price of the metal itself is a major industrial issue.

<Fluorescent compound>
A general fluorescent compound is not particularly required to be a heavy metal complex such as a phosphorescent compound, and a so-called organic compound composed of a combination of general elements such as carbon, oxygen, nitrogen, and hydrogen is used. Applicable. Furthermore, it is possible to use other non-metallic elements such as phosphorus, sulfur and silicon, and it is possible to use complexes of typical metals such as aluminum and zinc.
However, since only 25% of excitons can be applied to light emission as described above with conventional fluorescent materials, high efficiency light emission such as phosphorescence emission cannot be expected.

<Delayed fluorescent compound>
[Excited triplet-triplet annihilation (TTA) delayed fluorescent compound]
In order to solve the problems of fluorescent compounds, a light emission method using delayed fluorescence has appeared. The TTA method that originates from collisions between triplet excitons can be described by the following general formula. That is, there is a merit that a part of triplet excitons, in which the energy of excitons has been converted only to heat due to non-radiation deactivation, can cross back to singlet excitons that can contribute to light emission. Even in an actual organic EL device, it is possible to obtain an external extraction quantum efficiency approximately twice that of a conventional fluorescent light emitting device.
General formula: T ^* + T ^* → S ^* + S
(In the formula, T ^* represents a triplet exciton, S ^* represents a singlet exciton, and S represents a ground state molecule.)
However, as can be seen from the above equation, since only one singlet exciton that can be used for light emission is generated from two triplet excitons, it is impossible in principle to obtain 100% internal quantum efficiency.

[Thermoactive delayed fluorescence (TADF) luminescent compound]
The TADF method, which is another highly efficient fluorescent emission, is a method that can solve the problems of TTA.
As described above, the fluorescent compound has the advantage that the molecule can be designed infinitely. That is, among the molecularly designed compounds, there is a compound in which the energy level difference between the triplet excited state and the singlet excited state (hereinafter referred to as ΔEst) is extremely close (see FIG. 1). .
Although such a compound does not have a heavy atom in the molecule, a reverse intersystem crossing from a triplet excited state to a singlet excited state, which cannot normally occur due to a small ΔEst, occurs. Furthermore, since the rate constant of deactivation from singlet excited state to ground state (= fluorescence emission) is extremely large, triplet excitons themselves are thermally deactivated to ground state (non-radiative deactivation). It is more kinetically advantageous to return to the ground state while emitting fluorescence via the singlet excited state. Therefore, TADF can ideally emit 100% fluorescence.

<Molecular design concept for ΔEst>
The molecular design for reducing the ΔEst will be described.
In order to reduce ΔEst, in principle, it is most effective to reduce the spatial overlap between the highest occupied orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in the molecule. It is.
In general, it is known that HOMO is distributed in electron donating sites and LUMO is distributed in electron withdrawing sites in the electron orbit of the molecule. By introducing an electron donating and electron withdrawing skeleton into the molecule, HOMO is distributed. It is possible to move away the position where LUMO exists.
For example, in Non-Patent Document 1 described above, by introducing an electron-withdrawing skeleton such as a cyano group, a sulfonyl group, or a triazine and an electron-donating skeleton such as a carbazole or a diphenylamino group, LUMO and HOMO Are localized.
It is also effective to reduce the change in molecular structure between the ground state and triplet excited state of the compound. As a method for reducing the structural change, for example, making the compound rigid is effective. Rigidity described here means that there are few sites that can move freely in the molecule, for example, by suppressing free rotation in the bond between rings in the molecule or by introducing a condensed ring with a large π conjugate plane. means. In particular, it is possible to reduce the structural change in the excited state by making the portion involved in light emission rigid.

<General problems with TADF compounds>
TADF compounds have various problems in terms of their light emission mechanism and molecular structure.
The following describes some of the problems generally associated with TADF compounds.
In the TADF compound, it is necessary to separate the HOMO and LUMO sites as much as possible in order to reduce ΔEst. Therefore, the electronic state of the molecule is a donor / acceptor type molecule in which the HOMO and LUMO sites are separated. It becomes a state close to the inner CT (intramolecular charge transfer state).
When there are a plurality of such molecules, stabilization is achieved by bringing the donor part of one molecule and the acceptor part of the other molecule close to each other. Such a stabilized state is not limited to the formation between two molecules, but can also be formed between a plurality of molecules such as three or five molecules. As a result, various stabilized states having a wide distribution exist, and the shapes of the absorption spectrum and the emission spectrum become broad. In addition, even when a multimolecular assembly exceeding two molecules is not formed, various existence states can be taken depending on the direction and angle of interaction between the two molecules. The shape of the emission spectrum becomes broad.

The broad emission spectrum leads to two major problems.
One problem is that the color purity of the emitted color is lowered. This is not a big problem when applied to lighting applications, but when used for electronic displays, the color gamut is small and the color reproducibility of pure colors is low. It becomes difficult.

Another problem is the rising wavelength on the short wavelength side of the emission spectrum ( "fluorescence Zero - Zero Band". Referred to as) of shorter wavelength, that is, high S ₁ (higher energy of the lowest excited singlet energy) It is to end.
Naturally, when the fluorescence zero-zero band is shortened, the phosphorescence zero-zero band derived from T ₁ having lower energy than S ₁ is also shortened (higher T ₁ ). Therefore, the compound used in the host compound in order not to cause reverse energy transfer from the dopant, arises the need to ₁ reduction and high T ₁ of high S.
This is a very big problem. A host compound consisting essentially of an organic compound takes a plurality of active and unstable chemical species such as a cation radical state, an anion radical state, and an excited state in an organic EL device. By expanding the π-conjugated system, it can exist relatively stably.

However, in order to achieve high S ₁ and high T ₁ , it is necessary to reduce or cut off the π-conjugated system in the molecule, which makes it difficult to achieve both stability and as a result. The life of the light emitting element is shortened.
In addition, in a TADF compound that does not contain a heavy metal, the transition that is deactivated from the triplet excited state to the ground state is a forbidden transition, and therefore the existence time (exciton lifetime) in the triplet excited state is several hundred microseconds to millisecond. It is very long with second order. Therefore, even if the T ₁ energy of the host compound is higher than that of the luminescent compound, the reverse energy transfer from the triplet excited state of the luminescent compound to the host compound due to the length of its existence time. The probability of waking up increases. As a result, the reverse reverse energy transfer from the triplet excited state to the singlet excited state of the originally intended TADF compound does not occur sufficiently, and unfavorable reverse energy transfer to the host compound becomes the mainstream, resulting in sufficient luminous efficiency. Inconvenience that cannot be obtained.

In order to solve the above problems, it is necessary to sharpen the emission spectrum shape of the TADF compound and reduce the difference between the emission maximum wavelength and the rising wavelength of the emission spectrum. This can be basically achieved by reducing the change in the molecular structure of the singlet excited state and the triplet excited state. Specifically, it is effective to use a ligand having a strong coordinating power, a multidentate ligand in which ligands are linked, and the like.
In order to suppress reverse energy transfer to the host compound, it is effective to shorten the existence time (exciton lifetime) of the triplet excited state of the TADF compound. To achieve this, it is necessary to take measures such as reducing the molecular structure change between the ground state and the triplet excited state and introducing suitable substituents and elements to undo the forbidden transition. Can be solved.

The present invention includes, as a design concept, a copper complex that suppresses the structural change of the excited state as described above and a copper complex that has a short existence time of the triplet excited state.
Below, the various measuring methods regarding the copper complex of this invention are described.

[Electron density distribution]
In the copper complex of the present invention, it is preferable that HOMO and LUMO are substantially separated in the molecule from the viewpoint of reducing ΔEst. The distribution states of these HOMO and LUMO can be obtained from the electron density distribution when the structure is optimized by molecular orbital calculation.
The calculation method of structure optimization and calculation of electron density distribution by molecular orbital calculation of copper complex in the present invention is calculated using molecular orbital calculation software using B3LYP as functional and 6-31G (d) as basis function. There is no particular limitation on the software, and any of them can be obtained similarly.
In the present invention, Gaussian 09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian, USA was used as molecular orbital calculation software.
Further, “HOMO and LUMO are substantially separated” means that the HOMO orbital distribution calculated by the above molecular calculation and the central part of the LUMO orbital distribution are separated, more preferably the HOMO orbital distribution and the LUMO orbital. This means that the distributions of do not overlap.
As for the separation state of HOMO and LUMO, from the above-described structure optimization calculation using B3LYP as the functional and 6-31G (d) as the basis function, the time-dependent density functional method (Time-Dependent DFT) is used. It is also possible to calculate the energy of S ₁ and T ₁ (respectively E (S ₁ ) and E (T ₁ )) by calculating the excited state and calculate ΔEst = E (S ₁ ) −E (T ₁ ). It is. As the calculated ΔEst is smaller, HOMO and LUMO are more separated. In the present invention, ΔEst calculated using the same calculation method as described above is preferably 0.5 eV or less, more preferably 0.2 eV or less, and further preferably 0.1 eV or less.

[Minimum excitation singlet energy S ₁ ]
The lowest excited singlet energy S ₁ of the copper complex in the present invention is defined in the present invention as calculated in the same manner as a normal method. That is, a sample to be measured is deposited on a quartz substrate to prepare a sample, and the absorption spectrum (vertical axis: absorbance, horizontal axis: wavelength) of this sample is measured at room temperature (300 K). A tangent line is drawn with respect to the rising edge of the absorption spectrum on the long wavelength side, and is calculated from a predetermined conversion formula based on the wavelength value at the intersection of the tangent line and the horizontal axis.
However, in the case where the copper complex used in the present invention has a relatively high aggregation property of the molecule itself, an error due to aggregation may occur in the measurement of the thin film. Considering that the Stokes shift of the copper complex in the present invention is relatively small and that the structural change between the excited state and the ground state is small, the lowest excited singlet energy S ₁ in the present invention is a copper complex at room temperature (25 ° C.). The peak value of the maximum emission wavelength in the solution state was used as an approximate value. Here, as the solvent to be used, a solvent that does not affect the aggregation state of the copper complex, that is, a solvent having a small influence of the solvent effect, for example, a nonpolar solvent such as cyclohexane or toluene can be used.

[Minimum excitation triplet energy T ₁ ]
The lowest excited triplet energy (T ₁ ) of the copper complex in the present invention can be calculated from the photoluminescence (PL) characteristics of a solution, a powdered solid, or a thin film. For example, as a calculation method for a thin film, after making a thin copper complex dispersion into a thin film, the transient PL characteristics are measured using a streak camera to separate the fluorescent component and the phosphorescent component, and the energy The lowest excited triplet energy can be obtained from the lowest excited singlet energy with the difference as ΔEst. The same applies to powder solids. In addition, in the case of the copper complex of this invention, since it can light-emit with a high quantum yield almost without the fall of the quantum yield resulting from aggregation etc. in a solid state, it can measure also in a solid state.
In measurement / evaluation, an absolute PL quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics) or the like can be used for measuring the absolute PL quantum yield. The light emission lifetime can be measured by exciting a sample with laser light using a streak camera C4334 (manufactured by Hamamatsu Photonics).
As in S _1, the peak value of the maximum emission wavelength in the solution state of the copper complex at low temperature (77K) can be used as an approximate value for the lowest excited triplet energy T ₁ in the present invention. This is because the system crossing due to heat does not occur in a low temperature state, and only light emission from the triplet, that is, phosphorescence is observed. Here, as the solvent to be used, a solvent that does not affect the aggregation state of the copper complex, that is, a solvent having a small influence of the solvent effect, for example, a nonpolar solvent such as cyclohexane or toluene can be used.

<< Constituent layers of organic EL elements >>
As typical element structures in the organic EL element of the present invention, the following structures can be exemplified, but the invention is not limited thereto.
(1) Anode / light emitting layer // cathode (2) Anode / light emitting layer / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer / cathode (4) Anode / hole transport layer / light emitting layer / Electron transport layer / cathode (5) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (6) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode (7) Anode / hole injection layer / hole transport layer / (electron blocking layer /) light emitting layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode Among the above, the configuration of (7) is Although used preferably, it is not limited to this.
The light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers.

If necessary, a hole blocking layer (also referred to as a hole blocking layer) or an electron injection layer (also referred to as a cathode buffer layer) may be provided between the light emitting layer and the cathode. An electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided therebetween.
The electron transport layer used in the present invention is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Moreover, you may be comprised by multiple layers.
The hole transport layer used in the present invention is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. Moreover, you may be comprised by multiple layers.
In the above-described typical element configuration, the layer excluding the anode and the cathode is also referred to as “organic layer”.

(Tandem structure)
The organic EL element of the present invention may be a so-called tandem element in which a plurality of light emitting units including at least one light emitting layer are stacked.
As typical element configurations of the tandem structure, for example, the following configurations can be given.
Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode Here, the first light emitting unit, the second light emitting unit and the third light emitting unit are all the same, May be different. Two light emitting units may be the same, and the remaining one may be different.
A plurality of light emitting units may be laminated directly or via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate layer. A known material structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.

Examples of materials used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiO _x , VO _x , CuI, InN, GaN, Conductive inorganic compound layers such as CuAlO ₂ , CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ and Al, two-layer films such as Au / Bi ₂ O ₃ , SnO ₂ / Ag / SnO ₂ , ZnO / Multi-layer film such as Ag / ZnO, Bi ₂ O ₃ / Au / Bi ₂ O ₃ , TiO ₂ / TiN / TiO ₂ , TiO ₂ / ZrN / TiO ₂ , fullerenes such as C ₆₀ , conductivity such as oligothiophene Examples include organic material layers, conductive organic compound layers such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, and metal-free porphyrins. The present invention is not limited thereto.
As a preferable configuration in the light emitting unit, for example, a configuration in which the anode and the cathode are excluded from the configurations (1) to (7) described in the above-described typical element configurations, and the like is described. It is not limited.

  Specific examples of the tandem organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734, US Pat. No. 6,337,492, International JP 2005/009087, JP 2006-228712, JP 2006-24791, JP 2006-49393, JP 2006-49394, JP 2006-49396, JP 2011. No. -96679, JP 2005-340187, JP 47114424, JP 34096681, JP 3884564, JP 431169, JP 2010-192719, JP 2009-076929, JP Open 2008-0784 No. 4, JP 2007-059848 A, JP 2003-272860 A, JP 2003-045676 A, International Publication No. 2005/094130, and the like. The present invention is not limited to these.

  Hereinafter, each layer which comprises the organic EL element of this invention is demonstrated.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that provides a field in which electrons and holes injected from an electrode or an adjacent layer are recombined to emit light via excitons, and the light emitting portion is a layer of the light emitting layer. Even within, it may be the interface between the light emitting layer and the adjacent layer. The structure of the light emitting layer according to the present invention is not particularly limited as long as it satisfies the requirements defined in the present invention.
The total thickness of the light emitting layer is not particularly limited, but it prevents the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color against the drive current. From a viewpoint, it is preferable to adjust to the range of 2 nm-5 micrometers, More preferably, it adjusts to the range of 2-500 nm, More preferably, it adjusts to the range of 5-200 nm.
The layer thickness of each light emitting layer according to the present invention is preferably adjusted to a range of 2 nm to 1 μm, more preferably adjusted to a range of 2 to 200 nm, and further preferably adjusted to a range of 3 to 150 nm. Is done.
The light-emitting layer according to the present invention contains the above-described light-emitting compound as a light-emitting dopant (light-emitting compound, dopant compound, also simply referred to as a dopant), and further includes the above-described host compound (matrix material, light-emitting host compound, simply host). It is also preferable to contain.

(1) Luminescent dopant As the luminescent dopant, a fluorescent luminescent dopant (also referred to as a fluorescent luminescent compound, a fluorescent dopant, or a fluorescent compound) and a phosphorescent dopant (phosphorescent compound, phosphorescent dopant, phosphorescence). It is also referred to as a functional compound). In the present invention, at least one light emitting layer contains a copper complex.
The concentration of the luminescent dopant in the luminescent layer can be arbitrarily determined based on the specific dopant used and the requirements of the device, and is contained at a uniform concentration in the thickness direction of the luminescent layer. It may also have an arbitrary concentration distribution.
Moreover, the light emission dopant used for this invention may be used in combination of multiple types, and may combine and use the combination of the dopants from which a structure differs, and the fluorescence emission dopant and a phosphorescence emission dopant. Thereby, arbitrary luminescent colors can be obtained.

The light emission color of the organic EL device of the present invention and the copper complex of the present invention is shown in FIG. 3.16 on page 108 of “New Color Science Handbook” (edited by the Japan Society for Color Science, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total of CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.
In the present invention, it is also preferable that the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting dopants having different emission colors and emits white light.
There are no particular limitations on the combination of the light-emitting dopants that exhibit white, and examples include blue and orange, and a combination of blue, green, and red. About the combination of these 2 types and 3 types of light emission dopant, all may be a delayed fluorescence light emission dopant, and may be combined with a phosphorescence emission dopant as mentioned above.
The white color in the organic EL device of the present invention means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is x = 0.39 ± 0.09 when the 2 ° viewing angle front luminance is measured by the method described above. Y = 0.38 ± 0.08.

(1.1) Fluorescent luminescent dopant The fluorescent luminescent dopant used for this invention is demonstrated.
The fluorescent light-emitting dopant used in the present invention is a copper complex. The copper complex preferably exhibits fluorescence, and more preferably exhibits delayed fluorescence.
Specifically, the copper complex has a structure represented by the following general formula (1).

In general formula (1), X represents an atom selected from an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. Y ₁ and Y ₂ each represent a ligand containing a coordination atom that forms a coordination bond with copper as a central metal, and each may form a ring or may be bonded via a linking group. The ligands represented by Y ₁ and Y ₂ each contain an atom selected from a phosphorus atom, a nitrogen atom, a sulfur atom, and an oxygen atom as a coordination atom. R represents a substituent.

Examples of the substituent represented by R include a substituted or unsubstituted aromatic ring group, heteroaromatic ring group, alkyl group, alkenyl group, alkynyl group, cycloalkyl group, silyl group, boryl group, and cyano group. Can be mentioned. Moreover, you may have a substituent further in these substituents.
The substituent represented by R is particularly preferably an aromatic ring group. Examples of the group that may further substitute these substituents include the same substituents as the substituents represented by R _{101 to} R ₁₀₄ described later.

In the general formula (1), any of the ligands represented by Y ₁ or Y ₂ preferably contains a phosphorus atom coordinated to copper as a central metal.
Furthermore, it is preferable that the ligands represented by Y ₁ and Y ₂ each contain a phosphorus atom that coordinates to copper as a central metal.

  In the general formula (1), the atom represented by X is preferably a sulfur atom.

  In the copper complex of the present invention, the structure represented by the general formula (1) is preferably a structure represented by the following general formula (2).

In general formula (2), X represents an atom selected from an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. L represents a substituted or unsubstituted divalent linking group. W represents a substituent. Z _{1 to} Z ₄ each represent a substituent, and may be different from each other. n1 to n4 each represents an integer of 0 or 1. m represents an integer of 0 to 5.

Examples of the divalent linking group represented by L include an alkylene group, an alkenylene group, a cycloalkylene group, an arylene group, and a heteroarylene group.
Examples of the substituent represented by W include an aromatic ring group, a heteroaromatic ring group, an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a silyl group, a boryl group, a cyano group, a nitro group, Examples thereof include a carbonyl group, a sulfonyl group, a halogen, a halogenated alkyl group, an amino group, an alkoxy group, and a sulfanyl group. The substituent represented by W is preferably an electron-withdrawing group (boryl group, cyano group, nitro group, carbonyl group, sulfonyl group, halogen, halogenated alkyl group, halogenated aryl group). (Halogenated alkyl group, halogenated aryl group) is more preferable.
Examples of the substituent represented by Z _{1 to} Z ₄ include an aromatic ring group, a heteroaromatic ring group, an alkenyl group, an alkynyl group, a silyl group, a boryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, Examples include halogen, halogenated alkyl group, sulfanyl group, alkyl group, amino group, alkoxy group, and cycloalkyl group. The carbon number is preferably in the range of 1-20.
These substituents may further have a substituent.

The substituents represented by Z _{1 to} Z ₄ may be the same substituents or different substituents. The substituent represented by Z _{1 to} Z ₄ is preferably an electron donating group (an alkyl group, an amino group, an alkoxy group, a cycloalkyl group, and a phenoxy group), and an alkyl group such as a methyl group or isopropyl group. More preferably, it is a group.
A preferable light-emitting compound used in the present invention may be a low-molecular compound having a molecular weight sufficient for sublimation purification or a polymer having a repeating unit.
In the case of a low molecular weight compound, sublimation purification is possible, so that there is an advantage that purification is easy and a high-purity material is easily obtained. The molecular weight is not particularly limited as long as sublimation purification is possible, but the preferred molecular weight is 3000 or less, more preferably 2000 or less.

Although the specific example of the copper complex of this invention is shown below, it is not limited to this.
The copper complex of the present invention has a tricoordinate structure, and a monodentate ligand -XR (M-1 to M-46) having an ionic valence of −1 which can be used as a ligand of the exemplary compound. Y ₁ and Y ₂ are bidentate ligands whose valence (the number of bonds (number of hands) that can be bonded as a linking group) is bonded through the divalent linking group L is zero. A combination with Y ₁ -L—Y ₂ — (N−1 to N-50) and one monodentate ligand with an ionic valence of −1, and ionic valences corresponding to Y ₁ and Y ₂ respectively. 0 valent monodentate ligands -Y ₁ and _{-Y 2 (P-1~P-12} ) shows a copper complex which consist of a combination of the two. That is, Table 1 shows exemplary compounds of the copper complex of the present invention as a combination of a monodentate ligand having an ionic valence of −1 and a bidentate ligand having an valence of 0. Table 2 shows exemplary compounds of the copper complex of the present invention as a combination of a monodentate ligand having an ionic valence of −1 and two monodentate ligands having an valence of 0.
In addition, * of monodentate ligand M-1 to M-46 and P-1 to P-12 represents a coordination position. Two atoms selected from a phosphorus atom, a nitrogen atom, a sulfur atom, and an oxygen atom contained in the bidentate ligands N-1 to N-50 are coordination atoms.

(1.2) Phosphorescent dopant The phosphorescent dopant used in the present invention will be described.
As will be described later, for example, when the light-emitting element of the present invention is used as a white light-emitting device such as a lighting device, a compound that emits light of a plurality of colors needs to be included in the light-emitting layer. In this case, at least one copper complex of the present invention may be included, and a compound other than the present invention may be further included. Examples of materials useful for white light emitting devices other than the present invention include phosphorescent dopants. The phosphorescent dopant is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 25 ° C. Although defined as 0.01 or more compounds, the preferred phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant used in the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. Just do it.
The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL device. Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Application Publication No. 2006/835469, US Patent Application Publication No. 2006 /. No. 0202194, U.S. Patent Application Publication No. 2007/0087321, U.S. Patent Application Publication No. 2005/0244673, Inorg. Chem. 40, 1704 (2001), Chem. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chem. Lett. 34, 592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Application Publication No. 2002/0034656, US Pat. No. 7,332,232, US Patent Application Publication No. 2009/0108737, United States Patent Application Publication No. 2009/0039776, United States Patent No. 6921915, United States Patent No. 6,687,266, United States Patent Application Publication No. 2007/0190359, United States Patent Application Publication No. 2006/0008670, United States Patent Application Publication No. 2009/0165846, United States Patent Application Publication No. 2008/0015355, United States Patent No. 7250226, United States Patent No. 7396598, United States Patent Application Publication No. 200 / 0263635 Pat, U.S. Patent Application Publication No. 2003/0138657, U.S. Patent Application Publication No. 2003/0152802, U.S. Patent No. 7090928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, US Patent Application Publication No. 2006/0251923, US Patent Application Publication No. 2005/0260441, US Pat. No. 7,393,599. , US Pat. No. 7,534,505, US Pat. No. 7,445,855, US Patent Application Publication No. 2007/0190359, US Patent Application Publication No. 2008/0297033, US Pat. No. 7,338,722, US Patent Application Publication No. 2002 / No. 134984, U.S. Pat. No. 7,279,704, U.S. Patent Application Publication No. 2006/098120, U.S. Patent Application Publication No. 2006/103874, International Publication No. 2005/076380, International Publication No. 2010/032663 International Publication No. 2008140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, US Patent Application Publication No. 2012/228583, US Patent Application Publication No. 2012/21211. No. 26, JP 2012-069737 A, Japanese Patent Application No. 2011-181303, JP 2009-114086, JP 2003-81988, JP 2002-302671, JP 2002-363552. No. gazette.
Among these, a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, or a metal-sulfur bond is preferable.

(2) Host compound The host compound used in the present invention is a compound mainly responsible for charge injection and transport in the light emitting layer, and its own light emission is not substantially observed in the organic EL device.
The host compound preferably has a mass ratio in the layer of 20% or more among the compounds contained in the light emitting layer.
A host compound may be used independently or may be used in combination of multiple types. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient.
The host compound that is preferably used in the present invention will be described below.

Although there is no restriction | limiting in particular as a host compound used with the copper complex in this invention, From the viewpoint of reverse energy transfer, what has excitation energy larger than the excitation singlet energy of the copper complex of this invention is preferable, and also the copper of this invention Those having an excited triplet energy greater than the excited triplet energy of the complex are more preferred.
The host compound is responsible for carrier transport and exciton generation in the light emitting layer. Therefore, it can exist stably in all active species states such as cation radical state, anion radical state, and excited state, and does not cause chemical changes such as decomposition and addition reaction. It is preferable not to move at the angstrom level.

In particular, when the light-emitting dopant used in combination exhibits TADF light emission, since the existence time of the triplet excited state of the TADF material is long, the T ₁ energy of the host compound itself is high, and the host compounds are associated with each other. In such a molecular structure that the host compound does not have a low T ₁ , such as not creating a low T ₁ state, TADF material and the host compound do not form an exciplex, or the host compound does not form an electromer due to an electric field. Appropriate design is required.
In order to satisfy these requirements, the host compound itself must have high electron hopping mobility, high hole hopping movement, and small structural change when it is in a triplet excited state. It is. Representative examples of host compounds that satisfy these requirements include high π-energy conjugated skeletons having high T ₁ energy such as carbazole skeleton, azacarbazole skeleton, dibenzofuran skeleton, dibenzothiophene skeleton, or azadibenzofuran skeleton. What has as a partial structure is mentioned preferably. In particular, when the light emitting layer contains a carbazole derivative, it is possible to promote appropriate carrier hopping and dispersion of the light emitting compound in the light emitting layer, and the effect of improving the light emitting performance of the device and the stability of the thin film can be obtained. Therefore, it is preferable.

Further, representative examples include compounds in which these rings have a biaryl and / or multiaryl structure. As used herein, “aryl” includes not only an aromatic hydrocarbon ring but also an aromatic heterocyclic ring.
More preferably, it is a compound in which a carbazole skeleton and a 14π-electron aromatic heterocyclic compound having a molecular structure different from that of the carbazole skeleton are directly bonded, and further a 14π-electron aromatic heterocyclic compound is incorporated in the molecule. A carbazole derivative having at least one is preferred. In particular, the carbazole derivative is preferably a compound having two or more conjugated structures having 14π electrons or more in order to further enhance the effects of the present invention.

Moreover, as a host compound used for this invention, the compound represented by the following general formula (I) is also preferable. This is because the compound represented by the following general formula (I) has a condensed ring structure, and therefore a π electron cloud spreads, the carrier transportability is high, and the glass transition temperature (Tg) is high. Further, generally, the condensed aromatic ring tends to have a small triplet energy (T ₁ ), but the compound represented by the general formula (I) has a high T ₁ and has a short emission wavelength (that is, T _1). and larger S ₁₎ it can be preferably used also for the copper complex.

In the general formula (I), X ₁₀₁ represents NR ₁₀₁ , an oxygen atom, a sulfur atom, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₂ R ₁₀₃ . y _{1 to} y ₈ each represents CR ₁₀₄ or a nitrogen atom.
R _{101 to} R ₁₀₄ each represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring.
Ar ₁₀₁ and Ar ₁₀₂ each represent an aromatic ring and may be the same or different.
n101 and n102 are each an integer of 0 to _4, when _{R 101} is a hydrogen atom, n101 represents 1-4.
R _{101 to} R ₁₀₄ in the general formula (I) represent hydrogen or a substituent, and the substituent referred to here refers to what may be contained within a range that does not inhibit the function of the host compound used in the present invention. In the case where a substituent is introduced in the synthetic scheme, the compound having the effect of the present invention is defined as being included in the present invention.

Examples of the substituent represented by each of R _{101 to} R ₁₀₄ include a linear or branched alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group). Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (aromatic Also called carbocyclic group, aryl group, etc. For example, benzene ring, biphenyl, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m- Terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, indene ring, fluorene ring A group derived from a fluoranthrene ring, a naphthacene ring, a pentacene ring, a perylene ring, a pentaphen ring, a picene ring, a pyrene ring, a pyrantolen ring, an anthraanthrene ring, tetralin, etc.), an aromatic heterocyclic group (for example, a furan ring) , Dibenzofuran ring, thiophene ring, dibenzothiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, Thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, Borin ring, diazacarbazole ring (group derived from a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom, etc. In addition, combining the carboline ring and the diazacarbazole ring Sometimes referred to as “azacarbazole ring”), non-aromatic hydrocarbon ring group (eg, cyclopentyl group, cyclohexyl group, etc.), non-aromatic heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl) Group), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group) Etc.), aryloxy group (for example, phenoxy group, naphthyloxy group) Etc.), alkylsulfanyl group (for example, methylsulfanyl group, ethylsulfanyl group, propylsulfanyl group, pentylsulfanyl group, hexylsulfanyl group, octylsulfanyl group, dodecylsulfanyl group, etc.), cycloalkylsulfanyl group (for example, cyclopentylsulfanyl group, Cyclohexylsulfanyl group, etc.), arylsulfanyl group (eg, phenylsulfanyl group, naphthylsulfanyl group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxy group) Carbonyl group etc.), aryloxycarbonyl group (eg phenyloxycarbonyl group, naphthyloxycarbonyl group etc.), sulfa Yl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthyl) Aminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, Phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, Rucarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group) Group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, Dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido) Group, octylureido group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl) Group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methyl) Sulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl) Group), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc. ), Halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon groups (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group Nitro group, hydroxy group, the thiol group, silyl groups (e.g., trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, a phenyl diethyl silyl group and the like), or the like deuterium atom.

These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.
As y _{1 to} y ₈ in the general formula (I), preferably at least three of y _{1 to} y ₄ or at least three of y _{5 to} y ₈ are represented by CR ₁₀₂ , more preferably y _{1 to} y ₈ are all CR ₁₀₂ . Such a skeleton is excellent in hole transport property or electron transport property, and can efficiently recombine and emit holes / electrons injected from the anode / cathode in the light emitting layer.
Among them, a compound in which X ₁₀₁ is NR ′, an oxygen atom, or a sulfur atom in general formula (I) is preferable as a structure having a low LUMO energy level and excellent electron transport properties. More preferably, the condensed ring formed with X ₁₀₁ and y _{1 to} y ₈ is a carbazole ring, an azacarbazole ring, a dibenzofuran ring or an azadibenzofuran ring.

Further, considering that it is preferable to make the host compound rigid, when X ₁₀₁ is NR ₁₀₁ , R ₁₀₁ is an aromatic hydrocarbon ring which is a π-conjugated skeleton among the substituents mentioned above. It is preferably a group or an aromatic heterocyclic group. Further, these R ₁₀₁ may be further substituted with a substituent represented by the aforementioned R _{101 to} R ₁₀₃ .
In the general formula (I), examples of the aromatic ring represented by Ar ₁₀₁ and Ar ₁₀₂ include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent similar to the substituents represented by R _{101 to} R ₁₀₄ described above.
In the general formula (I), examples of the aromatic hydrocarbon ring represented by Ar ₁₀₁ and Ar ₁₀₂ include the aromatic hydrocarbon rings exemplified as the substituents represented by the aforementioned R _{101 to} R _104. Examples include the same ring as the group.

In the partial structure represented by the general formula (I), examples of the aromatic heterocycle represented by Ar ₁₀₁ and Ar ₁₀₂ include the substituents represented by R _{101 to} R ₁₀₄ described above. The same ring as an aromatic heterocyclic group is mentioned.
In view of the purpose that the host compound represented by the general formula (I) has a large T ₁ , the aromatic ring itself represented by Ar ₁₀₁ and Ar ₁₀₂ preferably has a high T ₁ , and the benzene ring (Including polyphenylene skeletons (biphenyl, terphenyl, quarterphenyl, etc.) with multiple benzene rings), fluorene ring, triphenylene ring, carbazole ring, azacarbazole ring, dibenzofuran ring, azadibenzofuran ring, dibenzothiophene ring, dibenzothiophene ring A pyridine ring, a pyrazine ring, an indoloindole ring, an indole ring, a benzofuran ring, a benzothiophene ring, an imidazole ring or a triazine ring is preferable. More preferred are a benzene ring, a carbazole ring, an azacarbazole ring and a dibenzofuran ring.
When Ar ₁₀₁ and Ar ₁₀₂ are a carbazole ring or an azacarbazole ring, it is more preferable that they are bonded at the N-position (or 9-position) or the 3-position.
When Ar ₁₀₁ and Ar ₁₀₂ are dibenzofuran rings, they are more preferably bonded at the 2-position or 4-position.
In addition to the above purpose, when considering the use of an organic EL element mounted in a vehicle, the environment temperature in the vehicle is assumed to be high, so the Tg of the host compound is high. Is also preferable. Therefore, for the purpose of increasing the Tg of the host compound represented by the general formula (I), each of the aromatic rings represented by Ar ₁ and Ar ₂ is preferably a condensed ring of 3 or more rings. .

Specific examples of the aromatic hydrocarbon condensed ring in which three or more rings are condensed include naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring , Benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthoperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen A ring, a picene ring, a pyranthrene ring, a coronene ring, a naphtho- coronene ring, an ovalen ring, an anthraanthrene ring, and the like. In addition, these rings may further have the above substituent.
Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, A Tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan Tren ring (naphthaldehyde thiophene ring), and the like. In addition, these rings may further have a substituent.

In the general formula (I), n101 and n102 are each preferably 0 to 2, more preferably n101 + n102 is 1 to 3. _Furthermore, since _{the R 101} is the n101 and n102 when the hydrogen atom is 0 at the same time, the general formula (I) only a low Tg small molecular weight of the host compounds represented by not _achievable, when _{R 101} is a hydrogen atom N101 represents 1-4.

  As the host compound used in the present invention, the carbazole derivative is preferably a compound having a structure represented by the general formula (II). This is because such a compound tends to have particularly excellent carrier transportability.

In formula _{(II), X 101, Ar} 101, Ar 102, n102 have the same meanings as _{X 101, Ar 101, Ar 102} , n102 in the formula (I).
n102 is preferably 0 to 2, more preferably 0 or 1.
In general formula (II), the condensed ring formed containing X ₁₀₁ may further have a substituent other than Ar ₁₀₁ and Ar ₁₀₂ as long as the function of the host compound used in the present invention is not impaired. .
Furthermore, it is preferable that the compound represented by general formula (II) is represented by the following general formula (III-1), (III-2), or (III-3).

In the general formula (III-1) ~ (III -3), X 101, Ar 102, n102 have the same meanings as _{X 101,} Ar 102, n102 in the general formula (II).
In the general formulas (III-1) to (III-3), the condensed ring, carbazole ring and benzene ring formed containing X ₁₀₁ are further substituted within a range not inhibiting the function of the host compound used in the present invention. You may have.
Examples of the host compound used in the present invention include compounds represented by the general formulas (I), (II), (III-1) to (III-3) and other structures. It is not limited to these.

The preferred host compound used in the present invention may be a low molecular compound having a molecular weight that can be purified by sublimation or a polymer having a repeating unit.
In the case of a low molecular weight compound, sublimation purification is possible, so that there is an advantage that purification is easy and a high-purity material is easily obtained. The molecular weight is not particularly limited as long as sublimation purification is possible, but the preferred molecular weight is 3000 or less, more preferably 2000 or less.
In the case of a polymer or oligomer having a repeating unit, there is an advantage that it is easy to form a film by a wet process, and since a polymer generally has a high Tg, it is also preferable from the viewpoint of heat resistance. The polymer used as the host compound used in the present invention is not particularly limited as long as the desired device performance can be achieved, but preferably the general formulas (I), (II), (III-1) to (III-) What has the structure of 3) in a principal chain or a side chain is preferable. Although there is no restriction | limiting in particular as molecular weight, Molecular weight 5000 or more is preferable or a thing with 10 or more repeating units is preferable.

In addition, the host compound has a hole transporting ability or an electron transporting ability, prevents the emission of light from being long-wavelength, and is stable with respect to heat generated when the organic EL element is driven at a high temperature or during the element driving. From the viewpoint of operation, it is preferable to have a high glass transition temperature (Tg). Tg is preferably 90 ° C. or higher, more preferably 120 ° C. or higher.
Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

《Electron transport layer》
In the present invention, the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
Although there is no restriction | limiting in particular about the total layer thickness of the electron carrying layer used for this invention, Usually, it is the range of 2 nm-5 micrometers, More preferably, it is 2-500 nm, More preferably, it is 5-200 nm.
Further, in the organic EL element, when the light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to wake up. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total thickness of the electron transport layer between several nanometers and several micrometers.
On the other hand, when the layer thickness of the electron transport layer is increased, the voltage is likely to increase. Therefore, particularly when the layer thickness is thick, the electron mobility of the electron transport layer is preferably 10 ⁻⁵ cm ² / Vs or more. .
The material used for the electron transport layer (hereinafter referred to as an electron transport material) may have any of an electron injecting property, a transporting property, and a hole blocking property. Any one can be selected and used.

  For example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, Dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene derivatives, etc.) That.

In addition, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7- Dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq) and the like, and their metal complexes A metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.
In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.
Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In the electron transport layer used in the present invention, the electron transport layer may be doped with a dopant as a guest material to form an electron transport layer having a high n property (electron rich). Examples of the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides. Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.

Specific examples of known preferable electron transport materials used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
US Pat. No. 6,528,187, US Pat. No. 7,230,107, US Patent Application Publication No. 2005/0025993, US Patent Application Publication No. 2004/0036077, US Patent Application Publication No. 2009/0115316, US Patent Application Publication No. 2009/0101870, United States Patent Application Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79, 156 (2001), U.S. Patent No. 7964293, U.S. Patent Application Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International Publication No. Public Publication No. 2006/067931, International Publication No. 2007/086552, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011/086935, International Publication No. 2010/150593, International Publication No. 2010/047707, EP23111826, JP2010-251675A, JP2009-209133A, JP2009-124114A, JP JP-A-2008-277810, JP-A-2006-156445, JP-A-2005-340122, JP-A-2003-45662, JP-A-2003-31367, JP-A-2003-282270, International Publication No. 2012. / 115034.

More preferable electron transport materials in the present invention include aromatic heterocyclic compounds containing at least one nitrogen atom. For example, pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, azadibenzofuran derivatives. , Azadibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, benzimidazole derivatives, and the like.
The electron transport material may be used alone or in combination of two or more.

《Hole blocking layer》
The hole blocking layer is a layer having the function of an electron transport layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved.
Moreover, the structure of the electron carrying layer mentioned above can be used as a hole-blocking layer used for this invention as needed.
The hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
The layer thickness of the hole blocking layer used in the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As the material used for the hole blocking layer, the material used for the above-described electron transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the hole blocking layer.

《Electron injection layer》
The electron injection layer (also referred to as “cathode buffer layer”) used in the present invention is a layer provided between the cathode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. 2 and Chapter 2 “Electrode Materials” (pages 123 to 166) of the 2nd edition of “The Forefront of Industrialization” (issued by NTT Corporation on November 30, 1998).
In the present invention, the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 0.1 to 5 nm, although it depends on the material. Moreover, the nonuniform layer (film | membrane) in which a constituent material exists intermittently may be sufficient.

The details of the electron injection layer are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by 8-hydroxyquinolinate lithium (Liq), and the like. Further, the above-described electron transport material can also be used.
Moreover, the material used for said electron injection layer may be used independently, and may be used in combination of multiple types.

《Hole transport layer》
In the present invention, the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
Although there is no restriction | limiting in particular about the total layer thickness of the positive hole transport layer used for this invention, Usually, it is the range of 5 nm-5 micrometers, More preferably, it is 2-500 nm, More preferably, it is 5-200 nm.
As a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymeric materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT / PSS, aniline copolymer, polyaniline, polythiophene, etc.).

Examples of the triarylamine derivative include benzidine type represented by α-NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl), starburst type represented by MTDATA, Examples include compounds having fluorene or anthracene in the triarylamine-linked core.
In addition, hexaazatriphenylene derivatives such as those described in JP-A-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
Furthermore, a hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC, as described in the literature (Applied Physics Letters 80 (2002), p. 139). Further, ortho-metalated organometallic complexes having Ir or Pt as the central metal as typified by Ir (ppy) ₃ are also preferably used.
Although the above-mentioned materials can be used as the hole transport material, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain. The polymer materials or oligomers used are preferably used.

Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not.
For example, Appl. Phys. Lett. 69, 2160 (1996), J. MoI. Lumin. 72-74, 985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chem. 3, 319 (1993), Adv. Mater. 6, 677 (1994), Chem. Mater. 15, 3148 (2003), US Patent Application Publication No. 2003/0162053, US Patent Application Publication No. 2002/0158242, US Patent Application Publication No. 2006/0240279, US Patent Application Publication No. 2008 / No. 0220265, U.S. Patent No. 5061569, International Publication No. 2007/002683, International Publication No. 2009/018009, EP650955, U.S. Patent Application Publication No. 2008/0124572, U.S. Patent Publication No. 2007/0278938. Specification, US Patent Application Publication No. 2008/0106190, US Patent Application Publication No. 2008/0018221, International Publication No. 2012/115034, Japanese Translation of PCT International Publication No. 2003-519432, Japanese Patent Application Laid-Open No. 2006-135145 , US Patent Application No. 13/585981 and the like.
The hole transport material may be used alone or in combination of two or more.

《Electron blocking layer》
The electron blocking layer is a layer having a function of a hole transport layer in a broad sense, and is preferably made of a material having a function of transporting holes and a small ability to transport electrons, and transporting electrons while transporting holes. The probability of recombination of electrons and holes can be improved by blocking.
Moreover, the structure of the positive hole transport layer mentioned above can be used as an electron blocking layer used for this invention as needed.
The electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
The thickness of the electron blocking layer used in the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the electron blocking layer.

《Hole injection layer》
The hole injection layer (also referred to as “anode buffer layer”) used in the present invention is a layer provided between the anode and the light emitting layer in order to lower the driving voltage or improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “Devices and the Forefront of Industrialization (issued by NTT Corporation on November 30, 1998)”.
In the present invention, the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
The details of the hole injection layer are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc. Examples of the material used for the hole injection layer include: Examples thereof include materials used for the above-described hole transport layer.
Among them, phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives as described in JP-T-2003-519432 and JP-A-2006-135145, metal oxides typified by vanadium oxide, amorphous carbon Preferred are conductive polymers such as polyaniline (emeraldine) and polythiophene, orthometalated complexes represented by tris (2-phenylpyridine) iridium complex, and triarylamine derivatives.
The materials used for the hole injection layer described above may be used alone or in combination of two or more.

"Additive"
The organic layer in the present invention described above may further contain other additives.
Examples of the additive include halogen elements such as bromine, iodine and chlorine, halogenated compounds, alkali metals and alkaline earth metals such as Pd, Ca, and Na, transition metal compounds, complexes, and salts.
The content of the additive can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and further preferably 50 ppm or less with respect to the total mass% of the contained layer. .
However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of favoring the exciton energy transfer.

<Method for forming organic layer>
A method for forming an organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) used in the present invention will be described.
The formation method of the organic layer used in the present invention is not particularly limited, and a conventionally known formation method such as a vacuum deposition method or a wet method (also referred to as a wet process) can be used.
Examples of the wet method include a spin coating method, a casting method, an ink jet method, a printing method, a die coating method, a blade coating method, a roll coating method, a spray coating method, a curtain coating method, and an LB method (Langmuir-Blodgett method). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method and a spray coating method is preferable.
Examples of the liquid medium for dissolving or dispersing the organic EL material used in the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, Aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.
Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.
Further, a different film forming method may be applied for each layer. When employing a vapor deposition method for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 ⁻⁶ to 10 ⁻² Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within a range of 50 nm / second, a substrate temperature of −50 to 300 ° C., and a layer (film) thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm.
The organic layer used in the present invention is preferably formed from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. In that case, it is preferable to perform the work in a dry inert gas atmosphere.

"anode"
As the anode in the organic EL element, a material having a work function (4 eV or more, preferably 4.5 eV or more) of a metal, an alloy, an electrically conductive compound, or a mixture thereof is preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used.
The anode may be formed by depositing a thin film of these electrode materials by vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.
Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less.
The film thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

"cathode"
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, aluminum, rare earth metals and the like. Among these, in terms of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.
In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.
Moreover, after producing the above metal with a film thickness of 1 to 20 nm on the cathode, a transparent or translucent cathode can be produced by producing a conductive transparent material mentioned in the description of the anode on the cathode. By applying the above, it is possible to manufacture a device in which both the anode and the cathode are transparent.

[Support substrate]
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. Or opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones, Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

An inorganic film, an organic film, or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / m ² · 24 h or less of a barrier film, and further, oxygen permeability measured by a method according to JIS K 7126-1987. However, it is preferable that the film has a high barrier property of 1 × 10 ⁻³ ml / m ² · 24 h · atm or less and a water vapor permeability of 1 × 10 ⁻⁵ g / m ² · 24 h or less.

As a material for forming the barrier film, any material may be used as long as it has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.
The external extraction quantum efficiency at room temperature (25 ° C.) of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
Here, external extraction quantum efficiency (%) = number of photons emitted to the outside of the organic EL element / number of electrons flowed to the organic EL element × 100.
In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination.

[Sealing]
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive. As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and it may be concave plate shape or flat plate shape. Moreover, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the organic EL element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / m ² · 24 h or less, and measured by a method according to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity 90 ± 2%) is preferably 1 × 10 ⁻³ g / m ² · 24 h or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of adhesives include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. There are no particular limitations on the method of forming these films. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate and the like), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.

[Protective film, protective plate]
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween. In particular, when sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, and the like used for the sealing can be used. Is preferably used.

[Light extraction improvement technology]
An organic EL element emits light inside a layer having a refractive index higher than that of air (within a refractive index of about 1.6 to 2.1), and is about 15% to 20% of light generated in the light emitting layer. It is generally said that it can only be taken out. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.

  As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, JP-A-63-314795), a method for forming a reflective surface on a side surface of an element (for example, JP-A-1-220394), a substrate, etc. A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Application Laid-Open No. 62-172691), lower refraction than the substrate between the substrate and the light emitter A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), and a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (including between the substrate and the outside world) ( JP-A-11 No. 283,751 Publication), and the like.

In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

[Condensing sheet]
The organic EL element of the present invention can be processed to provide a structure on a microlens array, for example, on the light extraction side of a support substrate (substrate) or combined with a so-called condensing sheet, for example, in a specific direction, for example, the element Condensing light in the front direction with respect to the light emitting surface can increase the luminance in a specific direction.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably within a range of 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and colored, and if it is too large, the thickness becomes thick, which is not preferable.
As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, a substrate may be formed with a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or the apex angle is rounded and the pitch is changed randomly. Other shapes may be used.
Moreover, in order to control the light emission angle from an organic EL element, you may use a light-diffusion plate and a film together with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

[Usage]
The organic EL element of the present invention can be used as an electronic device such as a display device, a display, and various light emitting devices.
Examples of light-emitting devices include lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.
In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like at the time of film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

  The light emission color of the organic EL device of the present invention and the compound used in the present invention is shown in FIG. 3.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the luminance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE chromaticity coordinates.

When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

<Lighting device>
The organic EL element of the present invention can also be used for a lighting device.
The organic EL element of the present invention may be used as an organic EL element having a resonator structure. Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.
Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a type for directly viewing a still image or a moving image. It may be used as a display device (display).
The driving method when used as a display device for reproducing a moving image may be either a passive matrix method or an active matrix method. Alternatively, it is possible to produce a full-color display device by using two or more organic EL elements of the present invention having different emission colors.

  Moreover, the copper complex of this invention is applicable to the organic EL element which produces substantially white light emission as an illuminating device. For example, when a plurality of luminescent compounds including a copper complex are used, white light emission can be obtained by simultaneously emitting a plurality of emission colors and mixing the colors. The combination of a plurality of emission colors may include three emission maximum wavelengths of three primary colors of red, green, and blue, or two of the complementary colors such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

In addition, the organic EL device forming method of the present invention may be simply arranged by providing a mask only when forming a light emitting layer, a hole transport layer, an electron transport layer, or the like, and separately coating with the mask. Since the other layers are common, patterning of a mask or the like is unnecessary, and for example, an electrode film can be formed on one surface by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like, and productivity is improved.
According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.

[One aspect of lighting device]
One mode of a lighting device including the organic EL element of the present invention will be described.
The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS. A device can be formed.
FIG. 2 shows a schematic view of the lighting device, and the organic EL element of the present invention (organic EL element 101 in the lighting device) is covered with a glass cover 102 (note that the sealing operation with the glass cover is performed by lighting. This was performed in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without bringing the organic EL element 101 in the apparatus into contact with the air.
FIG. 3 shows a cross-sectional view of the lighting device. In FIG. 3, 105 denotes a cathode, 106 denotes an organic layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.
By using the organic EL element of the present invention, a lighting device with improved luminous efficiency can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

[Example 1]
The synthesis | combining method and identification data of the copper complex Cu-36 of this invention, Cu-37, and Cu-45 are shown.
Moreover, about Cu-36, the result of having performed single crystal X-ray structural analysis is also shown.

  [Synthesis Method of Cu-36]

Under an argon atmosphere, 8.2 mg (0.34 mmol) of sodium hydride was dispersed in 25 ml of tetrahydrofuran in a Schlenk tube, and 37.6 mg (0.34 mmol) of benzenethiol was added. After stirring for 30 minutes, 200 mg (0.31 mmol) of 1,2-bisditolylphosphinobenzenecopper (I) bromide was added and further stirred to react. After stirring for 1 hour, the insoluble material was filtered off and the resulting solution was concentrated to 3 ml. By slowly adding 25 ml of diethyl ether, Cu-36 was obtained as white crystals (142 mg, 68% yield). Identification was performed by ¹ H-NMR, ³¹ P-NMR, elemental analysis, and single crystal X-ray structural analysis (see FIG. 4).

¹ H-NMR (400 MHz, CD ₂ Cl ₂ , 220K): δ = 2.26 (s, 6H, methyl), 2.42 (s, 6H, methyl), 6.50 (m, 2H, o-tolyl) ), 6.55 (t, 2H, phenyl), 6.63 (t, 1H, phenyl), 6.75 (m, 2H, o-tolyl), 6.80 (t, 2H, o-tolyl), 6.98 (d, 2H, J = 7.26 Hz, phenyl), 7.07 (t, 2H, o-tolyl), 7.14 (m, 4H, o-tolyl), 7.26 (m, 4H) , O-phenylene), 7.39 (t, 2H, o-tolyl), 7.51 (m, 2H, o-tolyl).
³¹ P NMR (162 MHz, CD ₂ Cl ₂ , 220K): δ = −24.4.
_{Calcd for C 40 H 37 CuP 2} S: C, 71.14; H, 5.52. Found: C, 71.06; H, 5.47
a single crystal X-ray diffraction study (at 90K): a = 10.8776 (1) Å, b = 13.0996 (2) Å, c = 13.2500 (2) Å, α = 82.651 (7 ) Deg, β = 76.9886 (9) deg, γ = 66.0524 (8) deg, V = 1679.05 (4) Å ³ , triclinic P-1, Z = 2, θ _{min / max} = 1. 58 / 30.2deg, 8531 unique observed reflections were used to refine 426 atomic parameters and gave a final R factor of 0.0324.

  [Synthesis Method of Cu-37]

Under an argon atmosphere, 7.0 mg (0.29 mmol) of sodium hydride was dispersed in 25 ml of tetrahydrofuran in a Schlenk tube, and 32.1 mg (0.29 mmol) of benzenethiol was added. After stirring for 30 minutes, 1,2-bis [bis (2-isopropylphenyl) phosphino] benzene copper (I) bromide (200 mg, 0.26 mmol) was added and stirred for further reaction. After stirring for 1 hour, the insoluble material was filtered off and the resulting solution was concentrated to 2 ml. By slowly adding 25 ml of diethyl ether, Cu-37 was obtained as white crystals (89 mg, yield 45%). Identification was performed by ¹ H-NMR, ³¹ P-NMR and elemental analysis.

¹ H-NMR (400 MHz, CD ₂ Cl ₂ , 220K): δ = 0.69 (d, 6H, J = 6.53 Hz, methyl), 0.72 (d, 6H, J = 6.60 Hz, methyl) , 0.85 (d, 6H, J = 6.60 Hz, methyl), 1.32 (d, 6H, J = 6.53 Hz, methyl), 3.35 (m, 2H, methyl), 3.63 ( m, 2H, methine), 6.47 (m, 2H, 2-iPrphenyl), 6.53 (t, 2H, phenyl), 6.60 (t, 1H, phenyl), 6.71 (t, 2H, phenyl), 6.81 (m, 2H, o-tolyl), 7.13 (m, 8H, phenyl and 2-iPrphenyl), 7.31 (m, 2H, 2-iPrphenyl), 7.44 ( , 4H, o-phenylene), 7.50 (m, 2H, 2-iPrphenyl).
³¹ P-NMR (162 MHz, CD ₂ Cl ₂ , 220K): δ = −26.2.
_{Calcd for C 48 H 53 CuP 2} S: C, 73.21; H, 6.78. Found: C, 73.12; H, 6.61.

  [Synthesis Method of Cu-45]

Under an argon atmosphere, 8.2 mg (0.34 mmol) of sodium hydride was dispersed in 25 ml of tetrahydrofuran in a Schlenk tube, and 61 mg (0.34 mmol) of p- (trifluoromethyl) benzenethiol was added. After stirring for 30 minutes, 200 mg (0.31 mmol) of 1,2-bisditolylphosphinobenzenecopper (I) bromide was added and further stirred to react. After stirring for 1 hour, the insoluble material was filtered off and the resulting solution was concentrated to 3 ml. By slowly adding 25 ml of diethyl ether, Cu-45 was obtained as white crystals (131 mg, 57% yield). Identification was performed by ¹ H-NMR, ³¹ P-NMR and elemental analysis.

¹ H-NMR (400 MHz, CD ₂ Cl ₂ , 220K): δ = 2.27 (s, 6H, methyl), 2.40 (s, 6H, methyl), 6.50 (m, 2H, o-tolyl) ), 6.75 (m, 4H, p-phenylene and o-tolyl), 6.81 (t, 2H, o-tolyl), 6.99 (d, 2H, J = 7.12 Hz, p-phenylene) , 7.08 (t, 2H, o-tolyl), 7.16 (t, 2H, o-tolyl), 7.22 (d, 2H, J = 8.07 Hz, o-tolyl), 7.27 ( m, 4H, o-phenylene), 7.40 (t, 2H, o-tolyl), 7.52 (t, 2H, o-tolyl).
³¹ P-NMR (162 MHz, CD ₂ Cl ₂ , 220K): δ = −24.5.
_{Calcd for C 41 H 36 CuF 3} P 2 S: C, 66.25; H, 4.88. Found: C, 66.49; H, 5.01.

(Sublimation confirmation)
When 100 mg of Cu-45 was mounted on a quartz sublimation boat and reduced in pressure to 1 × 10 ⁻⁶ Pa, the sublimation boat was heated to 230 ° C., it was confirmed that it sublimated. Moreover, when the obtained sublimate was collected and the emission spectrum and the NMR spectrum were measured, it showed the same spectrum as the spectrum before sublimation, and it was confirmed that sublimation was possible without decomposition.

The crystal emission characteristics of Cu-36, Cu-37, and Cu-45 were measured. The delayed fluorescence emission was determined by measuring the quantum yield and the emission lifetime.
Specifically, for each of Cu-36, Cu-37, and Cu-45, emission spectra at 77K and 293K (20 ° C.) were measured, and the emission lifetime was calculated. In addition, the Photo Luminescence (PL) quantum yield at 293K was calculated.

Here, if the light emission lifetime at 20 ° C. is in the microsecond level, it is considered that triplet is involved in light emission, and phosphorescence or delayed fluorescence is emitted.
Another feature of delayed fluorescence emission is that the emission lifetime at room temperature is significantly shorter than the emission lifetime at low temperatures. For example, even if a phosphorescent compound having a quantum yield of 0.1 at room temperature is assumed that non-radiation deactivation is completely suppressed at low temperature, the emission lifetime at low temperature is 10 times the emission lifetime at room temperature. It is. On the other hand, delayed fluorescent compounds emit light from a singlet at room temperature, but emit light from a triplet at low temperature, so the light emission lifetime at low temperature is more than 10 times the light emission lifetime at room temperature. It is also observed that it is longer than the order of magnitude.

  Further, the temperature characteristic of the emission intensity is also a judgment material for delayed fluorescence emission. In the case of a delayed fluorescence compound, the emission intensity increases with increasing temperature. Therefore, it is possible to determine whether the compound is a delayed fluorescent compound from the emission lifetime, the relationship between the emission lifetime and the quantum yield, and the temperature characteristics of the emission intensity.

The absolute spectrum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics) was used for the measurement of the emission spectrum and the PL quantum yield. The light emission lifetime was measured using a streak camera C4334 (manufactured by Hamamatsu Photonics) while exciting the sample with laser light.
The emission spectrum at 293K is shown in FIGS. 5 to 7 using a sample formed by sandwiching Cu-36, Cu-37 and Cu-45 crystal powders between two quartz glasses and pressing them. In addition, Table 3 shows the emission maximum wavelength and emission lifetime obtained from the emission spectrum.

From the emission spectrum of Cu-36 at 293K, the maximum emission wavelength at 20 ° C. is 488 nm (see FIG. 5), and the maximum emission wavelength at 77K is 481 nm. It was found to be a long wavelength.
On the other hand, the emission start wavelength was 415 nm at 20 ° C. and 424 nm at 77 K, and the shorter wavelength was at 20 ° C. The reason why the maximum emission wavelength at 20 ° C. was longer was considered that the first emission peak at low temperature was weak. Furthermore, the emission lifetime was 6.6 microseconds at 20 ° C. and 1200 microseconds at 77K, and the emission lifetime at 77K was 182 times the emission lifetime at 20 ° C.
From the above emission characteristics, it can be said that Cu-36 is a delayed fluorescence compound.

From the emission spectrum of Cu-37 at 293K, the maximum emission wavelength at 20 ° C. is 500 nm (see FIG. 6), and the maximum emission wavelength at 77K is 504 nm, so the emission wavelength of 77K is longer. It turned out to be a wavelength.
This is considered to be because light emission from a singlet is observed at 293K, but light emission is observed from a triplet having a lower energy level than singlet at 77K. Therefore, it can be said that Cu-37 is a delayed fluorescence compound.

From the emission spectrum of Cu-45 at 293K, the maximum emission wavelength at 20 ° C. is 482 nm (see FIG. 7), and the maximum emission wavelength at 77K is 495 nm, so the emission wavelength of 77K is longer. I found out that
Therefore, it can be said that Cu-45 is a delayed fluorescent compound, like Cu-37.

[Example 2]
(Method for producing vapor deposition type organic EL element 2)
A transparent substrate with an ITO (Indium Tin Oxide) film formed at a thickness of 150 nm as a positive electrode on a glass substrate of 50 mm × 50 mm and a thickness of 0.7 mm, patterned, and then attached with this ITO transparent electrode After ultrasonic cleaning with isopropyl alcohol, drying with dry nitrogen gas and UV ozone cleaning for 5 minutes, this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an amount optimal for device fabrication. The evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.
After reducing the vacuum to 1 × 10 ⁻⁴ Pa, the deposition crucible containing α-NPD was energized and heated, and deposited on the ITO transparent electrode at a deposition rate of 0.1 nm / second. A hole injection transport layer was formed. Next, the deposition crucible containing 1,3-bis (9-carbazolyl) benzene (mCP) and Cu-45 was heated by energization, and the deposition rate was 0.1 nm so as to be 95% and 5% by volume, respectively. A light emitting layer having a layer thickness of 40 nm was formed by vapor deposition on the hole transport layer at a rate of / sec.

  Thereafter, bathocuproine (BCP) was deposited at a deposition rate of 0.1 nm / second to form an electron transport layer having a layer thickness of 30 nm.

Furthermore, after forming lithium fluoride with a film thickness of 0.5 nm, 100 nm of aluminum was vapor-deposited to form a cathode.
The non-light-emitting surface side of the above element was covered with a can-shaped glass case in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more, and an electrode lead-out wiring was installed to produce an organic EL element 2.

When the produced organic EL device 2 was allowed to emit light at room temperature (25 ° C.) under a constant current condition of ^2.5 mA / cm ² , green light emission was confirmed. This emission spectrum was similar to the PL spectrum (λmax 506 nm) of a thin film in which only the light emitting layer was formed on a quartz substrate.

[Example 3]
(Method for producing coating type organic EL element 3)
A transparent substrate with an ITO (Indium Tin Oxide) film formed at a thickness of 150 nm as a positive electrode on a glass substrate of 50 mm × 50 mm and a thickness of 0.7 mm, patterned, and then attached with this ITO transparent electrode Was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

A solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (hereinafter abbreviated as PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083) to 70% with pure water on this ITO substrate is 3000 rpm. After forming the film by spin coating in 30 seconds, the film was dried at 200 ° C. for 1 hour to form a hole injection layer having a thickness of 30 nm.
The substrate on which this hole injection layer was formed was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and Poly-N, N-bis [4- (butylphenyl) manufactured by American Daissource Co., Ltd., which is a hole transport material. -N, N-bis (phenyl) benzidine], a solution of poly-TPD dissolved in 0.5% in chlorobenzene was formed by spin coating at 1500 rpm for 30 seconds, and then kept at 160 ° C. for 30 minutes. A 30 nm hole transport layer was formed.

Next, a light emitting layer composition 3 having the following composition was formed by spin coating at 1500 rpm for 30 seconds, and then held at 120 ° C. for 30 minutes to form a light emitting layer having a thickness of 40 nm.
<Light emitting layer composition 3>
Host compound: mCP 13.95 parts by mass Luminescent dopant: Cu-37 0.70 parts by mass Toluene 2000 parts by mass

Subsequently, the substrate was attached to a vacuum deposition apparatus without being exposed to the air atmosphere. A molybdenum resistance heating boat with bathocuproin (BCP) and lithium fluoride in it is attached to a vacuum deposition apparatus, and the vacuum chamber is depressurized to 4 × 10 ⁻⁵ Pa, and then the boat is energized and heated. BCP forms an electron transport layer with a deposition thickness of 0.1 nm / second and a layer thickness of 30 nm, and further forms a thin film with a thickness of 0.5 nm on the electron transport layer with lithium fluoride at 0.02 nm / second. Thus, an electron injection layer was formed. Subsequently, an aluminum thin film was deposited with a thickness of 100 nm to form a cathode.
The non-light-emitting surface side of the element was covered with a can-shaped glass case in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more, and an electrode lead-out wiring was installed to prepare an organic EL element 3.

When the produced organic EL element 3 was allowed to emit light at room temperature (25 ° C.) under a constant current condition of ^2.5 mA / cm ² , blue-green light emission was confirmed. This emission spectrum was an EL spectrum (λmax 509 nm) shifted blue compared to the PL spectrum (λmax 529 nm) of a thin film in which only the light emitting layer was formed on a quartz substrate.

[Example 4]
(Durability evaluation)
Using the compound of the present invention and Comparative Compound 1 described in Non-Patent Document 4 as a comparison, the light emission durability of the material in a PMMA (Poly (methymethacrylate)) matrix was evaluated.
Two glass substrates having a size of 50 mm × 50 mm and a thickness of 0.7 mm were ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

Next, a light emitting layer composition 4 having the following composition was formed by spin coating at 500 rpm for 30 seconds, and then held at 120 ° C. for 30 minutes in a nitrogen atmosphere to form a thin film 4 having a thickness of 40 nm.
<Light emitting layer composition 4>
Matrix: PMMA 10.00 parts by mass Luminescent dopant: Comparative compound 1 0.45 parts by mass Dichloromethane 1000 parts by mass

The thin film 5 was formed using the light emitting layer composition 5 having the following composition in the same procedure as the thin film 4.
<Light emitting layer composition 5>
Matrix: PMMA 10.00 parts by mass Luminescent dopant: Cu-37 0.42 parts by mass Dichloromethane 1000 parts by mass The concentration of the luminescent dopant in the matrix of the luminescent layer compositions 4 and 5 was adjusted to 5.3 mol%.

  The obtained thin films 4 and 5 were wiped into a predetermined shape, and the side on which the thin film was formed was covered and sealed with a can-shaped glass case in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more.

After measuring the emission spectra of the sealed thin films 4 and 5, irradiation was performed with a 365 nm laser (LC8 manufactured by Hamamatsu Photonics) for 20 minutes. Evaluation was made by comparing with strength. This evaluation is considered to be related to the stability of the compound when exposed to an excited state for a long time, and it is considered that the higher the residual ratio, the more stable the compound.
Residual ratio Comparative compound 1 29%
Compound Cu-37 of the present invention 38%

(effect)
From the above, Cu-36, Cu-37 and Cu-45 of the present invention are delayed fluorescent metal complexes, and Cu-37 and Cu-45 have excellent characteristics as light-emitting compounds for organic EL devices. It became clear to have. Moreover, it became clear that this invention Cu-37 is a compound excellent in durability.
It was found that the copper complex of the present invention has basic characteristics (high emission quantum efficiency, high durability, suitability for production capable of forming a film by both sublimation and coating).

DESCRIPTION OF SYMBOLS 101 Organic EL element 102 in lighting apparatus Glass cover 105 Cathode 106 Organic layer 107 Glass substrate 108 with a transparent electrode Nitrogen gas 109 Water-absorbing agent

Claims (2)

The copper complex characterized by having a structure represented by following General formula (2) .

(In General Formula (2), X represents a sulfur atom. L represents an arylene group. W represents a halogenated alkyl group. Z _{1 to} Z ₄ each represents an alkyl group and are different from each other. N1 to n4 each represents an integer of 0 or 1. m represents an integer of 0 to 5.) An organic electroluminescence device having at least one light emitting layer sandwiched between an anode and a cathode,
An organic electroluminescent device comprising the light emitting layer containing the copper complex according to claim 1 .

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