JP6036204B2 - Organic electroluminescence element, display device and lighting device - Google Patents

Description

  The present invention relates to an organic electroluminescence element, a display device using the organic electroluminescence element, and a lighting device. More specifically, the present invention relates to an organic electroluminescence element having high luminous efficiency, a long emission lifetime, and a low driving voltage, and a display device and an illumination device using the organic electroluminescence element.

  Conventionally, as a light-emitting electronic display device, there is an electroluminescence display (hereinafter referred to as “ELD”). As a component of ELD, an inorganic electroluminescent element and an organic electroluminescent element are mentioned.

  Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements. An organic electroluminescent device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and excitons (excitons) are generated by injecting electrons and holes into the light emitting layer and recombining them. It is an element that emits light by utilizing light emission (fluorescence / phosphorescence) when this exciton is deactivated. The organic electroluminescence device can emit light at a voltage of several volts to several tens of volts. Further, since it is a self-luminous type, it has a wide viewing angle, high visibility, and is a thin film type solid state device. It attracts attention from the viewpoint of space saving and portability.

  However, in the organic electroluminescence element for practical use in the future, development of an organic electroluminescence element that emits light efficiently and with high luminance with lower power consumption is desired.

  In recent years, a phosphorescent compound has been actively studied as one of techniques for increasing luminous efficiency. This phosphorescent compound is attracting attention as a lighting application because it may have a luminous efficiency almost equal to that of a cold cathode tube.

  The method using such a phosphorescent compound is an extremely high potential method. However, in an organic EL device using a phosphorescent compound, a method for controlling the position of the emission center, in particular, the emission layer is used. The luminous efficiency and lifetime of the organic electroluminescent device depend on how the carriers can be recombined internally to stabilize the light emission and how the phosphorescent compound itself can improve the light emission. From this point of view, it is an extremely important technical issue.

  As compounds (dopants) for blue phosphorescence used in organic electroluminescence devices, for example, iridium complexes having a phenylpyrazole structure, an imidazophenanthridine structure, and a phenylimidazole structure as a ligand are known. However, these iridium complexes still have problems to satisfy the luminous efficiency (luminance), short wavelength emission characteristics (blue compatibility) and high durability at the same time.

  An iridium complex having a phenylimidazole-based ligand is known to be a material having a relatively short emission wavelength (see, for example, Patent Document 1). However, it is difficult to say that the conventionally known techniques have completely solved problems such as further life extension of the element and resistance to discoloration of the emitted color over time.

  Furthermore, an iridium complex aimed at improving the thermal stability of the compound itself by binding ligands of the iridium complex to form a tetradentate or higher polydentate ligand is disclosed (for example, patents) Reference 2). In each technique disclosed in Patent Document 2, a certain effect can be seen with respect to the improvement of the device lifetime, but the problem with respect to the stability of the emission color over time is said to be completely solved. hard.

  In recent years, a cyclometalated platinum complex using platinum instead of iridium as a central metal has attracted attention (see, for example, Non-Patent Document 1 and Patent Document 3). Among them, a platinum complex having a tetravalent platinum atom as a central metal has recently been disclosed to realize the stability of the complex itself by improving heat resistance and the high luminous efficiency of an organic EL device (for example, Patent Document 4, 5).

  The tetravalent platinum complex in Patent Document 4 has three bidentate ligands, and the coordination mode with respect to the central metal is an octahedral type. For this reason, it has been reported that quenching due to stacking between identical molecules can be suppressed and luminous efficiency has been improved as compared with a bivalent platinum complex whose coordination mode is a planar type.

  However, since the carrier injecting property from the adjacent layer, particularly the carrier injecting property from the electron transporting layer is lowered, the effect of improving the light emission efficiency is not sufficient.

International Publication No. 2006/046980 International Publication No. 2005/113563 JP 2007-84635 A JP 2009-1114086 A JP 2007-99961 A

Rashidi et al. Dalton Trans. No. 4, pages 619-622 (2004)

  The present invention has been made in view of the above-described problems and situations, and the problem to be solved is to use an organic electroluminescence element having high luminous efficiency, a long emission lifetime, and a low driving voltage, and the organic electroluminescence element. Display device and lighting device.

  As a result of studying the cause of the above problems in order to solve the above problems, the present inventor has a light emitting layer containing a hexacoordinate tetravalent platinum complex coordinated with a carbene ligand as a light emitting material, and emitting light. When the electron transport layer adjacent to the cathode side of the layer contains a compound having an aromatic heterocycle containing a nitrogen atom, an organic electroluminescence device with high emission efficiency, long emission lifetime, and low driving voltage is obtained. As a result, the present invention has been found.

  That is, the said subject which concerns on this invention is solved by the following means.

一般式（Ａ）
（式中、Ｐｔは、白金原子を表し；Ｋは、無電荷の一座または二座配位子を表し；Ｌは、一座または二座の、モノアニオン性またはジアニオン性配位子を表し；ｍは、０〜５の整数を表し；ｏは、０〜５の整数を表し；ｎは、１〜３の整数を表し；ｐは、錯体の荷電数であり、０〜４の整数を表し；Ｗ−は、モノアニオン性の対イオンを表し；ｍ、ｏ、ｎおよびｐは、Ｐｔである白金原子の酸化状態と配位数、または、配位子の電荷と錯体の全体として電荷に依存し；Ｙ１、Ｙ２、Ｙ３およびＹ４は、各々独立して、水素、アルキル基、シクロアルキル基、ヘテロシクロアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルケニル基、アルキニル基またはアルコシキ基を表し、これらの基は置換されていても非置換であってもよく；Ｙ１とＹ２、Ｙ２とＹ３およびＹ３とＹ４は、各々独立に、それらの一部が結合して一体となって、窒素原子間に少なくとも２個の原子を有する飽和又は不飽和の環構造を形成していてもよく、これらの環構造の一個以上の原子はアルキル基またはアリール基で置換されていてもよく（これらの置換基はさらに置換されていてもまたは無置換であってもよく）、またこれらの環構造はさらに、一個以上の環構造を形成していてもよく；Ｒ１およびＲ２は、各々独立して、水素、アルキル基、シクロアルキル基、ヘテロシクロアルキル基、アリール基、アラルキル基、ヘテロアリール基、アルケニル基、アルキニル基またはアルコキシ基を表し、これらの基は置換されていても無置換であってもよい。） 1. An organic electroluminescent device having a light emitting layer and an electron transport layer adjacent to the cathode side of the light emitting layer between an anode and a cathode,
The light-emitting layer contains a hexacoordinate tetravalent platinum complex having a polydentate ligand (except for the case where it is a dicarbene transition metal complex represented by the following general formula (A)) ,
At least one of the polydentate ligands is a carbene ligand having a site coordinated to a platinum atom,
An organic electroluminescence device, wherein the electron transport layer adjacent to the cathode side of the light emitting layer contains a compound having an aromatic heterocycle containing a nitrogen atom as a skeleton.

Formula (A)
Wherein Pt represents a platinum atom; K represents an uncharged monodentate or bidentate ligand; L represents a monodentate or bidentate monoanionic or dianionic ligand; m Represents an integer of 0 to 5; o represents an integer of 0 to 5; n represents an integer of 1 to 3; p represents the number of charges of the complex, and represents an integer of 0 to 4; W- represents a monoanionic counter ion; m, o, n and p depend on the oxidation state and coordination number of the platinum atom which is Pt, or the charge of the ligand and the overall charge of the complex Y1, Y2, Y3 and Y4 each independently represents hydrogen, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group, an alkynyl group or an alkoxy group. These groups may be substituted or unsubstituted. Each of Y1 and Y2, Y2 and Y3, and Y3 and Y4 independently forms a saturated or unsaturated ring structure having at least two atoms between nitrogen atoms. And one or more atoms of these ring structures may be substituted with an alkyl group or an aryl group (these substituents may be further substituted or unsubstituted) In addition, these ring structures may further form one or more ring structures; each of R 1 and R 2 independently represents hydrogen, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, an aralkyl group, A group, a heteroaryl group, an alkenyl group, an alkynyl group or an alkoxy group, and these groups may be substituted or unsubstituted.)

  2. 2. The organic electroluminescence device according to item 1, wherein the hexacoordinate tetravalent platinum complex is a compound represented by the following general formula (I).

(In general formula (I), Pt represents a platinum atom having a coordination number of 6 and tetravalent. Ring A represents an aromatic ring formed together with Y ₁ and a carbon atom, and further has a substituent. The substituents may be bonded to each other to form a ring, Y ₁ represents a carbon atom or a nitrogen atom, and X _{1 to} X ₄ represent a 5-membered aromatic together with a carbene carbon atom coordinated to Pt. Is a group of atoms forming a group heterocycle, and represents a carbon atom, C—R ₁ , nitrogen atom, N—R ₁ , oxygen atom or sulfur atom, and at least one represents a nitrogen atom or N—R _{1. 1} represents a hydrogen atom or a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. And the two L ₁ may be the same or different from each other.)
3. 3. The organic electroluminescence device according to item 2, wherein the ring A in the general formula (I) represents a 5-membered or 6-membered aromatic ring.

  4). 4. The organic electroluminescence device according to item 2 or 3, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (II).

(In General Formula (II), Pt represents a tetravalent platinum atom having a coordination number of 6. Y ₂ to Y ₆ are an atomic group that forms a 6-membered aromatic ring together with a carbon atom coordinated to Pt. And represents a carbon atom, C—R ₂ or a nitrogen atom, wherein X ₅ and X ₆ are a group of atoms forming a 5-membered aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and C—R ₃ or nitrogen R ₂ and R ₃ represent a hydrogen atom or a substituent, R ₄ represents a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, and m and n represent an integer of 1 or more. And satisfies the relational expression m + n = 3.When m is 2, the two L ₁ may be the same or different from each other.)
5. 5. The organic electroluminescence device according to item 4, wherein the compound represented by the general formula (II) is a compound represented by the following general formula (III).

(In General Formula (III), X ₇ and X ₈ are carbon atoms having a single bond or a double bond, and may have a substituent. R _{6 to} R ₉ represent a hydrogen atom or a substituent. , R ₅ represents a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. Two L ₁ may be the same or different from each other.)
6). 2. The organic electrolysis according to item 1, wherein the hexacoordinate tetravalent platinum complex is a platinum complex having at least one tridentate carbene ligand represented by the following general formula (IV): Luminescence element.

(In general formula (IV), Pt represents a tetravalent platinum atom having a coordination number of 6. Ring B, ring C and ring D represent an aromatic ring, at least one of which is an aromatic heterocycle containing a nitrogen atom. Ring B, Ring C and Ring D may have a substituent, and these substituents may be bonded to each other to form a ring V, W and Z are carbon atoms, carbene A carbon atom or a nitrogen atom, at least one of which is a carbene carbon atom, L ₁ represents an auxiliary ligand coordinated to Pt, and p represents 1 or 2. When p is 2, two L ₁ may be the same as or different from each other.
7). In the said general formula (IV), both V and Z are carbene carbon atoms, or only W is a carbene carbon atom, The organic electroluminescent element of Claim 6 characterized by the above-mentioned.

  8). The compound having an aromatic heterocycle containing a nitrogen atom contained in an electron transport layer adjacent to the cathode side of the light emitting layer as a skeleton is a compound having a pyridine ring as a skeleton. The organic electroluminescence device according to any one of items 7 to 7.

  9. 9. The organic electroluminescence device according to item 8, wherein the compound having a pyridine ring as a skeleton is a pyridine derivative or an azacarbazole derivative.

10. 10. The organic electroluminescence device according to item 9, wherein the compound having a pyridine ring as a skeleton is an azacarbazole derivative.
11 . The organic electroluminescence device according to any one of items 1 to 10 , wherein the organic electroluminescence device has a plurality of light emitting layers.

12 . The organic electroluminescence element according to any one of items 1 to 11, wherein the organic electroluminescence element contains two or more kinds of light-emitting materials and the emission color is white.

13 . A display device comprising the organic electroluminescence element according to any one of items 1 to 12 .

14 . A lighting device comprising the organic electroluminescence element according to any one of items 1 to 12 .

  By the above means of the present invention, it is possible to provide an organic electroluminescence device having high luminous efficiency, long luminous lifetime, and low driving voltage. In addition, a display device and a lighting device using the organic electroluminescence element can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  The tetravalent platinum complex has three bidentate ligands, and the coordination mode with respect to the central metal is an octahedral type. Therefore, compared with a bivalent platinum complex whose coordination mode is a planar type, there is an effect that quenching due to stacking between the same molecules can be suppressed. On the other hand, it is considered that the problem that the carrier injection property from the adjacent layer is lowered due to the difficulty of hopping of carriers due to the structure that is difficult to stack. In particular, it has been clarified that the influence of a decrease in the injection property of electrons from the electron transport layer is large.

  Therefore, by containing a nitrogen-containing compound in the electron transport layer adjacent to the light-emitting layer and a hexacoordinate tetravalent platinum complex having a carbene ligand in the light-emitting layer, electrons from the electron transport layer to the light-emitting layer can be obtained. It is considered that the luminous efficiency is improved by improving the injection property. In addition, the use of a carbene ligand is considered to improve the stability of the complex itself and extend the lifetime of the light-emitting element.

  That is, when the electron transport material is composed of a compound having an aromatic heterocycle containing a nitrogen atom, the interaction between the carbene ligand and the electron transport material is strong at the interface between the light emitting layer and the electron transport layer (EML-ETL). Thus, it has been found that the electron injecting property is improved. This also contributes to reduction of the driving voltage of the element.

Furthermore, at least one of the polydentate ligands has the following effects by being a carbene ligand having a site that coordinates to a platinum atom.
(1) The coordination power of the carbene atom to the central metal is strong, and the complex itself is stable. (2) The structure in the excited state is stable. These are considered to contribute to extending the lifetime of the device.

  The reason why the structure of the excited state is stabilized is considered to be as follows.

In the carbene ligand in the hexacoordinate tetravalent platinum complex, the X ₁ -Y ₁ bond axis in the general formula (I) is twisted as compared with the phenyl-pyridine ligand or the phenyl-imidazole ligand. Coordinates to the platinum atom and the entire ligand is non-planar. This form is the most stable structure in the complex.

  In general, when a ground state is changed to an excited state, distortion occurs with a structural change of the complex. However, since the complex according to the present invention is originally twisted in the ground state, the structural change associated with the excited state is small and distortion is unlikely to occur. Therefore, it can be said that the structure is still stable even in the excited state. Therefore, the deterioration with time in the excited state is small, and it is presumed that the lifetime of the organic electroluminescence element has been extended.

  In the present invention, the “carbene ligand” refers to a ligand having a carbene carbon atom as a coordination site. In the present invention, a polydentate ligand having two or more coordination sites refers to a ligand in which at least one coordination site is a carbene carbon atom.

Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of the display unit of the display device of FIG. Schematic diagram of a pixel of the display device of FIG. Schematic diagram of passive matrix type full color display device Schematic diagram showing an example of a lighting device Sectional drawing which shows an example of an illuminating device

  The organic electroluminescence device of the present invention (hereinafter also referred to as “organic EL device”) is an organic EL device having a light emitting layer and an electron transport layer adjacent to the cathode side of the light emitting layer between an anode and a cathode. The light-emitting layer contains a hexacoordinate tetravalent platinum complex having at least one polydentate ligand, and at least one of the polydentate ligands is a site that is coordinated to a platinum atom. The electron transport layer adjacent to the cathode side of the light emitting layer contains a compound having an aromatic heterocycle containing a nitrogen atom as a skeleton. This feature is a technical feature common to the inventions according to claims 1 to 13.

  As an embodiment of the present invention, from the viewpoint of expression of the effect of the present invention, the hexacoordinate tetravalent platinum complex is a compound represented by the general formula (I), the luminous efficiency (luminance), It is preferable because the effect of simultaneously satisfying short wavelength light emission characteristics (blue compatibility) and high durability can be obtained.

  Furthermore, in the present invention, it is preferable that the ring A in the general formula (I) is a 5-membered or 6-membered aromatic ring because an effect of exhibiting short wavelength light emission characteristics (blue compatibility) is obtained.

  Furthermore, in this invention, it has an aromatic heterocyclic ring containing the nitrogen atom of an electron carrying layer that the compound represented by the said general formula (I) is a compound represented by the said general formula (II) The strong interaction with the compound is preferable because the electron injecting property is improved and the driving voltage can be reduced.

  Furthermore, in the present invention, the compound represented by the general formula (II) is a compound represented by the general formula (III), whereby the stability of the complex itself in an excited state is improved, and the device is Since the effect of extending the life is obtained, it is preferable.

  Furthermore, in the present invention, the hexacoordinate tetravalent platinum complex is a platinum complex having at least one tridentate carbene ligand represented by the following general formula (IV): (Brightness), short wavelength emission characteristics (blue compatibility), and high durability are obtained at the same time.

  Furthermore, in the present invention, in the general formula (IV), both V and Z are carbene carbon atoms, or only W is a carbene carbon atom, which improves the stability of the complex itself in an excited state. However, it is preferable because an effect of extending the life of the element can be obtained.

  Furthermore, in the present invention, the compound having an aromatic heterocyclic ring containing a nitrogen atom contained in an electron transport layer adjacent to the cathode side of the light emitting layer as a skeleton is a compound having a pyridine ring as a skeleton, It is preferable that the interaction with the hexacoordinate tetravalent platinum complex which is a light-emitting dopant is strengthened, so that the electron injecting property is improved and the driving voltage can be reduced.

  Furthermore, in the present invention, it is preferable that the compound having the pyridine ring as a skeleton is a pyridine derivative or an azacarbazole derivative, because an effect of improving electron injection property is obtained by stronger interaction.

  Furthermore, in the present invention, it is preferable that the organic EL element has a plurality of light-emitting layers because an effect of providing a long-life organic EL element in which a change in emission color with time is suppressed can be obtained.

  Furthermore, in the present invention, it is preferable that the organic EL element contains two or more kinds of light emitting materials and the light emission color is white because an effect that can be provided in a display device, a lighting device, and the like is obtained.

  The organic EL element of the present invention can be suitably included in a display device and a lighting device. As a result, a display device and a lighting device with low driving voltage, high luminance, and excellent durability 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.

≪Organic electroluminescence element≫
The organic EL device of the present invention is an organic EL device having a light emitting layer and an electron transport layer adjacent to the cathode side of the light emitting layer between an anode and a cathode, the light emitting layer comprising a multidentate ligand. A hexacoordinate tetravalent platinum complex having at least one of the above, and at least one of the polydentate ligands is a carbene ligand having a site coordinated to a platinum atom, The electron transport layer adjacent to the cathode side is characterized by containing a compound having an aromatic heterocycle containing a nitrogen atom as a skeleton.

≪Six coordinated tetravalent platinum complex≫
The hexacoordinate tetravalent platinum complex having at least one multidentate ligand according to the present invention will be described below. The hexacoordinate tetravalent platinum complex according to the present invention is contained in the light emitting layer as a phosphorescent compound (also referred to as a light emitting dopant or a phosphorescent dopant).

  The hexacoordinate tetravalent platinum complex according to the present invention is preferably a compound represented by the following general formula (I).

In general formula (I), Pt represents a tetravalent platinum atom having a coordination number of 6. Ring A formed together with Y ₁ and the carbon atom represents an aromatic ring, and may further have a substituent, and these substituents may be bonded to each other to form a ring. Y ₁ represents a carbon atom or a nitrogen atom. X _{1 to} X ₄ are a group of atoms that form a 5-membered aromatic heterocycle with a carbene carbon atom coordinated to Pt, and are a carbon atom, C—R ₁ , nitrogen atom, N—R ₁ , oxygen atom or sulfur. Represents an atom, and at least one represents a nitrogen atom or N—R ₁ . R ₁ represents a hydrogen atom or a substituent. L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. When m is 2, the two L ₁ may be the same or different from each other.

The ring A formed together with Y ₁ and the carbon atom in the general formula (I) is preferably a 5-membered or 6-membered aromatic ring.

  Examples of the aromatic ring represented by the ring A in the general formula (I) include a benzene ring, naphthalene ring, biphenyl 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, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene Examples thereof include aromatic hydrocarbon rings such as a ring and anthraanthrene ring.

  In addition, furan ring, thiophene ring, oxazole 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, Benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, and diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is nitrogen An aromatic heterocycle such as a ring substituted with an atom). Among these, a thiophene ring, a pyridine ring, a carbazole ring, a carboline ring, and a diazacarbazole ring are preferable.

Examples of the 5-membered aromatic heterocycle formed with the carbene carbon atom coordinated to X _{1 to} X ₄ and Pt in the general formula (I) include a pyrazole ring, an imidazole ring, a thiazole ring, an oxazole ring, and an isoxazole ring. , Indole ring, triazole ring, benzimidazole ring, benzopyrazole ring, benzothiazole ring, benzoxazole ring, and benzoisoxazole ring. Among these, an imidazole ring, a thiazole ring, an oxazole ring, and a triazole ring are preferable.

  Examples of the substituent substituted on the 5-membered or 6-membered aromatic ring represented by the ring A include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, (t) butyl group, pentyl group). Group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl Group (for example, propargyl group), aryl group (also called aromatic hydrocarbon ring group, for example, phenyl group, tolyl group, xylyl group, naphthyl group, biphenylyl group, anthryl group, phenanthryl group, etc.), heterocyclic group ( For example, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), aromatic heterocyclic group (for example, For example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-triazol-1-yl group, 1,2,3- Triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group , Indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (in which one of carbon atoms constituting carboline ring is replaced by nitrogen atom), quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl Group), alkoki 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.), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group) Cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octylio) Xycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyl) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl 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.), 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 (eg, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (eg, methyl Carbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propyl) Aminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfinyl Groups (eg, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexyl group) Rusulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group or arylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), 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.), nitro group, cyano group and the like. Among these, a methyl group, an isopropyl group, a (t) butyl group, and a cyclohexyl group are preferable.

  The above substituent may further have a substituent, and the aromatic ring is further substituted with an aromatic ring hydrocarbon group, an aromatic heterocyclic group or the like to form a condensed ring structure. It is also possible.

Examples of the substituent represented by R ₁ include a substituent substituted on the 5-membered or 6-membered aromatic ring represented by the ring A.

  The compound represented by the general formula (I) is preferably a compound represented by the following general formula (II).

In general formula (II), Pt represents a tetravalent platinum atom having a coordination number of 6. Y ₂ to Y ₆ is a group of atoms forming an aromatic ring of 6 members together with the carbon atom coordinating to Pt, it represents a carbon atom, C-R ₂ or a nitrogen atom. X ₅ and X ₆ are an atomic group forming a 5-membered aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₂ and R ₃ represent a hydrogen atom or a substituent, and R ₄ represents a substituent. L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. When m is 2, the two L ₁ may be the same or different from each other.

The 6-membered aromatic ring formed together with the carbon atoms coordinated to Y _{2 to} Y ₆ and Pt in the general formula (II) includes a benzene ring, a naphthalene ring, a biphenyl ring, an azulene ring, an anthracene ring, and a phenanthrene ring. , Pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring , Aromatic hydrocarbon rings such as perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, and anthraanthrene ring.

  Also, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring And an aromatic heterocycle such as a diazacarbazole ring (which represents a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom). Among these, a pyridine ring, a triazine ring, a carbazole ring, a carboline ring, and a diazacarbazole ring are preferable.

In addition, these aromatic rings may have a substituent, and examples of the substituent include a substituent that substitutes for the 5-membered or 6-membered aromatic ring represented by the ring A. Examples of the substituent represented by R ₂ , R _3, and R ₄ include a substituent substituted on the 5-membered or 6-membered aromatic ring represented by the ring A.

X ₅ and X ₆ in the general formula (II) include an imidazole ring, a benzimidazole ring, a triazole ring and the like as the 5-membered aromatic heterocycle formed together with a carbene carbon atom and a nitrogen atom. Among these, an imidazole ring is preferable.

  These aromatic heterocycles may have a substituent, and examples of the substituent include a substituent that substitutes for the 5-membered or 6-membered aromatic ring represented by the ring A.

  The compound represented by the general formula (II) is preferably a compound represented by the following general formula (III).

In general formula (III), X ₇ and X ₈ are carbon atoms having a single bond or a double bond, and may have a substituent. R _{6 to} R ₉ represent a hydrogen atom or a substituent, and R ₅ represents a substituent. L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. When m is 2, the two L ₁ may be the same or different from each other.

Examples of the substituent represented by R _{5 to} R ₉ and the substituent substituted on X ₇ and X ₈ include a substituent substituted on the 5-membered or 6-membered aromatic ring represented by the ring A. .

  The hexacoordinate tetravalent platinum complex is preferably a platinum complex having at least one tridentate carbene ligand represented by the following general formula (IV).

In the general formula (IV), Pt represents a tetravalent platinum atom having a coordination number of 6. Ring B, Ring C and Ring D represent an aromatic ring, at least one is an aromatic heterocycle containing a nitrogen atom, and Ring B, Ring C and Ring D may have a substituent, The substituents may be bonded to each other to form a ring. V, W and Z are a carbon atom, a carbene carbon atom or a nitrogen atom, and at least one is a carbene carbon atom. L ₁ represents an auxiliary ligand coordinated to Pt, and p represents 1 or 2. When p is 2, two L ₁ may be the same or different from each other.

  Ring B, ring C and ring D in the general formula (IV) include benzene ring, naphthalene ring, biphenyl ring, azulene ring, anthracene ring, phenanthrene ring, quinoline ring, benzoquinoline ring, pyrene ring, chrysene ring, naphthacene. Ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene Ring, pyranthrene ring, anthraanthrene ring and the like. The aromatic heterocycle includes furan ring, thiophene ring, oxazole 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, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, and diazacarbazole ring (the carbon atom of the hydrocarbon ring constituting the carboline ring) One of which represents a ring further substituted with a nitrogen atom). Among these, a benzene ring, a pyridine ring, a quinoline ring, and a benzoquinoline ring are preferable.

  Examples of the substituent substituted on the ring B, ring C, and ring D include a substituent substituted on the 5-membered or 6-membered aromatic ring represented by the ring A.

  In the general formula (IV), it is preferable that both V and Z are carbene carbon atoms, or only W is a carbene carbon atom.

<Description of auxiliary ligand>
As the general formula auxiliary ligand represented by L ₁ in the general formula (IV) from (I), conventionally known ones can be used. By selecting an auxiliary ligand, it is possible to optimize the emission wavelength and improve the emission quantum efficiency. Alternatively, the interaction between the complexes can be suppressed by the steric effect of the auxiliary ligand, whereby the light emission efficiency when an organic EL element is obtained can be improved.

  One or a plurality of auxiliary ligands may be used. When there are a plurality of auxiliary ligands, they may be the same or different from each other, but the valence and coordination between the central metal and the platinum atom may be different. The number must be satisfied, i.e. a hexacoordinate tetravalent platinum complex as a whole must be formed.

  When there are a plurality of vacant coordination sites, a bidentate ligand is more preferable in order to obtain stabilization of the complex itself by a chelate effect.

  Conventionally known ligands used for metal complexes include, for example, “Photochemistry and Photophysics of Coordination Compounds” Springer-Verlag H. Published by Yersin in 1987, “Organometallic Chemistry-Fundamentals and Applications-” Liu Huabo Company, Akio Yamamoto, published in 1982, etc. (for example, halogen ligands (preferably chlorine ligands), Nitrogen heterocyclic ligands (for example, bipyridyl, phenanthroline, etc.) and diketone ligands). Furthermore, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabol, picolinic acid, carbene, and the like can be used in combination as preferable ligands.

  Hereinafter, the auxiliary ligand capable of constituting the hexacoordinate tetravalent platinum complex according to the present invention will be described.

(Minus monovalent anionic monodentate ligand)
The minus monovalent anionic monodentate ligand represents a monodentate ligand that forms a covalent bond with a platinum atom. The coordination atom of the ligand is preferably a carbon atom, a hydrogen atom, an oxygen atom, a fluorine atom, or a chlorine atom.

(Minus monovalent anionic bidentate ligand)
The minus monovalent anionic bidentate ligand represents a bidentate ligand that forms a covalent bond and a coordinate bond with the platinum atom. The coordination atom of the ligand is preferably a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, or a phosphorus atom.

(Minus divalent anionic bidentate ligand)
The minus divalent anionic bidentate ligand represents a bidentate ligand that forms a covalent bond with a platinum atom. As a coordination atom of the ligand, a combination of a carbon atom and a nitrogen atom is preferable, and a phenylpyridine ligand, a phenylimidazole ligand, and a benzoquinoline ligand are preferable.

  The hexacoordinate tetravalent platinum complex according to the present invention is preferably a neutral complex (nonionic). This is because a neutral metal complex is easily sublimated because there is no ionic interaction between the complexes, and is advantageous for sublimation purification of the metal complex and vacuum deposition for producing an organic EL device. Specific examples of the hexacoordinate tetravalent platinum complex according to the present invention are illustrated below.

(Exemplary compounds)

  These hexacoordinate tetravalent platinum complexes can be synthesized by a known method.

≪Compound having aromatic heterocycle containing nitrogen atom as skeleton≫
The constituent material of the electron transport layer adjacent to the cathode side of the light emitting layer of the organic EL device of the present invention (hereinafter referred to as electron transport material) is “a compound having a nitrogen atom-containing aromatic heterocycle as a skeleton”. Chosen from. Aromatic heterocycles containing a nitrogen atom include pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, quinoline ring, isoquinoline ring, benzoquinoline ring, cincinoline ring Quinoxaline ring, carbazole ring, indole ring, isoindole ring, carboline ring, diazacarboline ring, carboline ring, azadibenzofuran ring, diazadibenzofuran ring, benzopyrazole ring, benzimidazole ring, benzotriazole ring, oxazole ring, oxazol ring Diazole ring, benzoxazole ring, benzooxadiazole ring, thiazole ring, thiadiazole ring, benzothiazole ring, benzothiadiazole ring, thiazolothiazole ring, phenanthroline ring, porphyrin ring, lid And cyanine ring, and preferably a compound having a pyridine ring as a skeleton, and more preferably pyridine derivative or aza carbazole derivative.

  Hereinafter, although the specific example of the compound which has the aromatic heterocyclic ring containing the nitrogen atom which concerns on this invention as a skeleton is shown, this invention is not limited to these.

(Exemplary compounds)

≪Configuration of organic EL element≫
Next, the configuration of the organic EL element of the present invention will be described in detail. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these. In this embodiment, the layer between the anode and the cathode corresponds to the organic layer.

(I) Anode / light emitting layer / cathode (ii) Anode / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iv) Anode / hole transport layer / Light emitting layer / hole blocking layer / electron transport layer / cathode (v) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer (cathode buffer layer) / cathode (vi) anode / Hole injection layer (anode buffer layer) / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer (cathode buffer layer) / cathode (vii) anode / hole transport layer / electron blocking layer / Light emitting layer / Hole blocking layer / Electron transport layer / Cathode In the organic EL device of the present invention, the light emitting layer is composed of, for example, a blue light emitting layer, a green light emitting layer, and a red light emitting layer. It can be set as a light emitting layer. At this time, the light emission maximum wavelength of the blue light emitting layer is preferably in the range of 430 to 480 nm, and the light emission maximum wavelength of the green light emitting layer is preferably in the range of 510 to 550 nm. The maximum wavelength is preferably a monochromatic light emitting layer in the range of 600 to 640 nm, and can be configured as a display device using these. Moreover, in the illuminating device of this invention, it is preferable to set it as the structure which laminated | stacked these at least 3 layers of light emitting layers, and made it the white light emitting layer. Further, a non-light emitting intermediate layer may be provided between the plurality of light emitting layers.

  Hereinafter, the detail of each structural layer which comprises an organic EL element is demonstrated.

<Light emitting layer>
The light-emitting layer according to the present invention contains a host compound and a dopant, and is a layer that emits light by recombination of electrons and holes injected from an electrode or an electron transport layer and a hole transport layer. It may be in the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

  The total thickness of the light emitting layer is not particularly limited, but it is 2 nm from the viewpoint of the uniformity of the film and the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color against the drive current. It is preferable to adjust to the range of -5 micrometers, More preferably, it adjusts to the range of 2-200 nm, Especially preferably, it is the range of 5-20 nm.

  For the formation of the light emitting layer, a dopant or host compound which is a metal complex according to the present invention is used, for example, a known thin film such as a vacuum deposition method, a wet coating method such as a spin coating method, a casting method, an LB method, or an inkjet method. The film can be formed by a chemical method. In the present invention, it is particularly preferable to form using a wet process method.

[Host compound]
As the host compound used in the light emitting layer constituting the organic EL device of the present invention, a known host compound is used.

  Here, in the present invention, the host compound is defined as a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.01 at room temperature (25 ° C.) among compounds contained in the light emitting layer.

  Further, a plurality of known host compounds may be used in combination. 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. In addition, by using a plurality of phosphorescent compounds, it is possible to mix different light emission, thereby obtaining an arbitrary emission color. White light emission is possible by adjusting the kind of phosphorescent compound as a dopant and the amount of doping, and can also be applied to illumination and backlight.

  As these known host compounds, compounds having a hole transporting ability and an electron transporting ability, preventing the emission of longer wavelengths, and having a high Tg (glass transition temperature) are preferable.

  Specific examples of known host compounds include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

Examples of host compounds preferably used in the organic EL device of the present invention are shown below.
(Exemplary compounds)

  Moreover, the light emitting layer may contain the host compound which has a fluorescence maximum wavelength further as a host compound. In this case, the energy transfer from the other host compound and the phosphorescent compound to the fluorescent compound allows electroluminescence as an organic EL element to be emitted from the other host compound having a fluorescence maximum wavelength. A host compound having a fluorescence maximum wavelength is preferably a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific host compounds having a maximum fluorescence wavelength include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Perylene dyes, stilbene dyes, polythiophene dyes, and the like. The fluorescence quantum yield can be measured by the method described in 362 (1992, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.

[Dopant]
A dopant is a light emitting material used with a host compound. The dopant includes a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound) and a fluorescent dopant (also referred to as a fluorescent dopant or a fluorescent compound). The tetravalent platinum complex is a phosphorescent dopant (phosphorescent compound).

(Phosphorescent compound)
As a material used for the light emitting layer (hereinafter referred to as a light emitting material), the above host compound is contained, and at the same time, the hexacoordinate tetravalent platinum complex according to the present invention is contained as a phosphorescent compound. Thereby, it can be set as an organic EL element with higher luminous efficiency.

  The phosphorescent compound according to the present invention is a compound in which light emission from an excited triplet is observed, is a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 0.2 at 25 ° C. 01 or more compounds. The phosphorescence quantum yield is preferably 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 quantum yield used in the present invention only needs to achieve the above phosphorescence quantum yield in any solvent.

  There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent compound. The energy transfer type is to obtain light emission from the phosphorescent compound by moving to the other, and the other is that the phosphorescent compound becomes a carrier trap, and carrier recombination occurs on the phosphorescent compound, and the phosphorescent compound emits light. Although it is a carrier trap type in which light emission is obtained, in any case, it is a condition that the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  In addition to the hexacoordinate tetravalent platinum complex having a polydentate ligand according to the present invention, it may further contain other known phosphorescent compounds, preferably group 8 to group 10 in the periodic table of elements. It is a complex compound containing a metal, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex compound), or a rare earth complex, and most preferably an iridium compound.

  Although the specific example of the well-known phosphorescent compound which can be used together for the light emitting layer of the organic EL element of this invention below is shown, this invention is not limited to these.

(Exemplary compounds)

  In the present invention, the phosphorescence emission maximum wavelength of the phosphorescent compound is not particularly limited, and can be obtained in principle by selecting a central metal, a ligand, a ligand substituent, and the like. Although the emission wavelength can be changed, it is preferable that the phosphorescent compound has a maximum phosphorescence emission wavelength of 380 to 480 nm. With such a blue phosphorescent organic EL element and a white phosphorescent organic EL element, the luminous efficiency can be further increased.

  The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 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 a total CS-1000 (manufactured by Konica Minolta Optics) is applied to the CIE chromaticity coordinates.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. The light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are one or two or more, or may have a laminated structure in which a plurality of layers having the same composition or different compositions are formed.

《Electron transport layer》
The electron transport layer is made of a material 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. The electron transport layer can be provided as a single layer or a plurality of layers.

  The electron transport layer has a function of transmitting electrons injected from the cathode to the light emitting layer. In the organic EL device of the present invention, the constituent material of the electron transport layer adjacent to the cathode side of the light emitting layer includes nitrogen atoms. A compound having an aromatic heterocyclic ring as a skeleton is used.

  In addition to the electron transport layer of the organic EL device of the present invention, a known electron transport material containing no nitrogen atom can be added. As the material, any one of conventionally known compounds can be selected and used. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquino Dimethane and anthrone derivatives and quinoxaline derivatives having a quinoxaline ring known as an electron withdrawing group can also be used as the electron transport material. Furthermore, 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 addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq ₃ ), 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 ₂ ), and the like, and the central metal of these metal complexes is In, Metal complexes replaced with 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 transporting material. A distyrylpyrazine derivative can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si or n-type-SiC can also be used as an electron transport material in the same manner as the hole injection layer and the hole transport layer. be able to.

  The electron transport layer is made of an electron transport material such as a vacuum deposition method, a wet method (also referred to as a wet process, such as a spin coating method, a casting method, a die coating method, a blade coating method, a roll coating method, an ink jet method, a printing method, or a spraying method. It is preferable to form the thin film by a coating method, a curtain coating method, an LB method (such as Langmuir-Blodgett method)).

  Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, about 5-5000 nm, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Further, an n-type dopant such as a metal compound such as a metal complex or a metal halide may be doped.

《Hole transport layer》
The hole transport layer is made of a hole transport material 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. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples include stilbene derivatives, silazane derivatives, and aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminobiphenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostyrylbenzene; and N-phenylcarbazole, as well as those described in US Pat. No. 5,061,569 Having four condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), and JP 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenyl in which triphenylamine units described in Japanese Patent No. 4-308688 are linked in three starburst types An amine (MTDATA) etc. are mentioned.

  Furthermore, 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 addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an inkjet method, or an LB method. Can do. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Next, an injection layer, a blocking layer and the like used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, exists between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. You may let them.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the hole injection layer (anode buffer layer) are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the electron injection layer (cathode buffer layer) are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer is an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and blocks holes while transporting electrons. Thus, the probability of recombination of electrons and holes can be improved.

  The film thickness of the hole blocking layer and the electron blocking layer is preferably 1 to 15 nm, and more preferably 3 to 10 nm.

  The hole blocking layer of the organic EL device of the present invention is provided adjacent to the light emitting layer.

  In the organic EL device of the present invention, when a hole blocking layer is provided adjacent to the cathode side of the light-emitting layer, the hole blocking layer has a “nitrogen-containing aromatic” according to the present invention described above as the hole blocking material. A compound having a heterocyclic ring. Thereby, it can be set as an organic EL element with much higher luminous efficiency. Further, the lifetime can be further increased.

  On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, conductive transparent materials such as CuI, ITO (Indium Tin Oxide), 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. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or when pattern accuracy is not required (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. 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. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low 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, rare earth metals and the like. Among these, from the point 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 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 light emission luminance is improved, which is convenient.

  Moreover, after producing the metal with a film thickness of 1 to 20 nm on the cathode, a transparent or translucent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

<Substrate>
The organic EL device of the present invention is preferably formed on a substrate.
The substrate (hereinafter also referred to as a 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. Although there is no restriction | limiting in particular, As a board | substrate used preferably, glass, quartz, and a transparent resin film can be mentioned, for example. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.

Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include films made of triacetate (TAC), cellulose acetate propionate (CAP), and the like. On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed as a barrier film. As the barrier film, the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by a method according to JIS K 7129-1992 is 0.01 g / (m ² · 24 h). ) The following barrier film is preferable, and the oxygen permeability measured by a method based on JIS K 7126-1987 is 1 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, water vapor A high barrier film having a transmittance of 1 × 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry 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. Furthermore, in order to improve the brittleness of the barrier film, it is more preferable to have a laminated structure of these inorganic layers and organic layers made of organic materials. 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, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but a method based on an atmospheric pressure plasma polymerization method described in JP-A-2004-68143 is homogeneous. It is particularly preferable from the viewpoint that a barrier film can be formed.

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, 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 sent 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. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a thin film made of a desired electrode material, for example, a material for an anode is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm to produce an anode. . Next, an organic compound thin film (organic layer) of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which is an organic EL element material, is formed thereon.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission occurs when a voltage of about 2 to 40 V is applied with the polarity of the anode being + (plus) and the cathode being-(minus). Observable. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

As a method for thinning the organic compound thin film, as described above, for example, a vacuum deposition method or a wet method (also referred to as a wet process, for example, a spin coating method, a casting method, a die coating method, a blade coating method, a roll coating method, The film is preferably formed by thinning by an inkjet method, a printing method, a spray coating method, a curtain coating method, or an LB method (such as Langmuir-Blodgett method)). The vacuum deposition method, the spin coating method, the ink jet method, and the printing method are particularly preferable from the viewpoints that a homogeneous film is easily obtained and that pinholes are not easily generated. Further, different film forming methods 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 the range of 50 nm / second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

  After forming these layers, a thin film made of a cathode material is usually formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness in the range of 10 nm to 5 μm, preferably 50 to 200 nm. A desired organic EL device can be obtained by providing a cathode. The organic EL element is preferably produced 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. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

<Display device>
The multicolor display device of the present invention is provided with a shadow mask only at the time of forming a light emitting layer, and the other layers are common, so patterning such as a shadow mask is unnecessary, and a vapor deposition method, a casting method, a spin coating method, an ink jet method on one side. Alternatively, the film can be formed by a printing method or the like. When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

  The display device of the present invention can be used as a display device, a display, and various light emission sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission. Alternatively, a single emission color, for example, white emission, can be changed to BGR using a color filter to achieve full color. Further, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.

  Examples of the display device and the display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in a car. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Moreover, you may use as an organic EL element which gave the organic EL element of this invention the 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.

  An example of a display device composed of organic EL elements will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 2 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below. FIG. 2 shows a case where the light L emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel circuit.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 holds the charged potential of the image data signal even if the driving of the switching transistor 11 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 4 is a schematic diagram of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  A combination of light emitting materials for obtaining a plurality of emission colors includes a combination of a plurality of phosphorescent or fluorescent materials (dopants), a light emitting material that emits fluorescence or phosphorescence, and the light emitting material. However, in the white organic EL device according to the present invention, a method of combining a plurality of dopants is preferable.

  As a layer structure of the organic EL element for obtaining a plurality of emission colors, a method of having a plurality of dopants exist in one emission layer, a plurality of emission layers, and different emission wavelengths in each emission layer Examples thereof include a method in which a dopant is present, and a method in which minute pixels emitting light having different wavelengths are formed in a matrix.

  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. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the platinum complex which concerns on this invention so that it may correspond to the wavelength range corresponding to CF (color filter) characteristic, Any one of known luminescent materials may be selected and combined to whiten.

《Lighting device》
The lighting device of the present invention includes home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, exposure light sources of electrophotographic copying machines, light sources of optical communication processors, light sensors Examples include, but are not limited to, a light source.

  One aspect of the lighting device of the present invention 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. 5 shows a schematic diagram of the lighting device.

  As shown in FIG. 5, the organic EL element 101 is covered with a glass cover 102.

  The sealing operation with the glass cover 102 is preferably performed in a glove box (in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere.

  FIG. 6 shows a cross-sectional view of the lighting device.

  As shown in FIG. 6, the lighting device mainly includes a cathode 105, an organic EL layer 106, and a glass substrate 107 with a transparent electrode, and these members are covered with a glass cover 102.

  The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

  As described above, the organic EL element of the present invention is not only the display device and the display, but also various light emitting sources, lighting devices, home lighting, interior lighting, a kind of lamp such as an exposure light source, and a liquid crystal display. It is also useful for display devices such as device backlights.

  In addition, backlights such as clocks, signboard advertisements, traffic lights, light sources such as optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processing machines, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

Example 1
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

  The structures of compounds other than the exemplified compounds used in the examples described below are shown below.

<< Production of Organic EL Element 1-1 >>
Patterning was performed on a substrate (NA-45, manufactured by AvanStrate Co., Ltd.) in which ITO (Indium Tin Oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. Thereafter, the transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

  On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS (HT-1), Baytron P Al4083, Baytron P Al4083) was diluted to 70% with pure water. A thin film was formed by spin coating using the solution, and then dried at 200 ° C. for 1 hour to provide a first hole transport layer having a thickness of 30 nm.

  On this first hole transport layer, poly [N, N′-bis (4-butylphenyl) -N, N′-diphenylbenzidine] (American Dye Source Co., Ltd., ADS-254) is used as a hole transport material. ) A thin film was formed by spin coating using a chlorobenzene solution of (HT-2). It heat-dried at 150 degreeC for 1 hour, and provided the 2nd hole transport layer with a film thickness of 40 nm.

This transparent support substrate was attached to a vacuum deposition apparatus, and the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa. Next, HOST-11 as a host compound and B-1-55 as a dopant are vapor-deposited on the second hole transport layer at a ratio of HOST-11: B-1-55 = 100: 6 by 30 nm. Was provided.

  Next, 20 nm of ET-32 as an electron transport material was deposited on the light emitting layer to provide an electron transport layer.

  Subsequently, 1.0 nm of lithium fluoride was vapor-deposited as an electron injection layer, and 110 nm of aluminum was vapor-deposited as a cathode, respectively, and the organic EL element 1-1 was produced.

<< Production of Organic EL Elements 1-2 to 1-7 >>
In the production of the organic EL element 1-2, the organic EL elements 1-2 to 1-7 were respectively produced in the same manner except that the dopant of the light emitting layer and the electron transport material were changed to the compounds shown in Table 1.

<< Evaluation of organic EL elements >>
Each evaluation was performed according to the following method about the organic EL element 1-1 to 1-7 produced as mentioned above.

(1) Evaluation of luminous efficiency For each organic EL element, an external extraction quantum efficiency (%) was measured when a constant current of ^2.5 mA / cm ² was applied at a room temperature of 23 ° C. in a dry nitrogen gas atmosphere. It was used as an index of luminous efficiency. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Optics) was used.

  The luminous efficiency was expressed as a relative value when the measured value of the external extraction quantum efficiency of the organic EL element 1-1 was 100. It represents that it is excellent in luminous efficiency, so that a numerical value is large.

(2) Evaluation of durability (half life) Each organic EL element was driven at a constant current under a constant environmental condition of 50 ° C. with a current giving an initial luminance of 1000 cd / m ^2, and 1/2 of the initial luminance (500 cd) / M ² ) The time required to reach (m ² ) (half life at high temperature storage) was determined and used as a measure of durability.

  Durability was calculated | required by the relative value which set the half life of the organic EL element 1-1 to 100. The larger the value, the longer the device life and the better the durability.

(3) Measurement of drive voltage The voltage when each organic EL element was driven at a room temperature (25 ° C.) under a constant current condition of ^2.5 mA / cm ² was obtained and used as the drive voltage.

  Next, the measured driving voltage of each organic EL element was determined as a relative value with the driving voltage of the organic EL element 1-1 being 100 according to the following formula.

Drive voltage (relative value) = (drive voltage of each organic EL element / drive voltage of the organic EL element 1-1) × 100
In addition, it shows that it can drive with a low voltage, so that the relative value of a drive voltage is small.
The evaluation results are shown in Table 1.

  As is clear from the results in Table 1, a hexacoordinate tetravalent platinum complex having a carbene ligand was used as a dopant for the light-emitting layer, and a compound having an aromatic heterocycle containing a nitrogen atom in the electron transport layer was used. The organic EL devices 1-3 to 1-7 of the present invention exhibited good characteristics such as high luminous efficiency, long half-life and low driving voltage. On the other hand, the electron transport property of the organic EL element 1-1 using the 6 coordinate tetravalent platinum complex (B-1-55) which does not have a carbene ligand as a dopant of a light emitting layer, and an electron carrying layer. The organic EL element 1-2 using an aromatic compound (ET-A) having no nitrogen atom as a material was inferior in any of the characteristics.

(Example 2)
The structures of compounds other than the exemplified compounds and the compounds used in the examples described below are shown below.

<< Preparation of Organic EL Element 2-1 >>
Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, manufactured by Bayer Co., Ltd., Baytron P) on the transparent support substrate provided with the ITO transparent electrode used in the production of the organic EL element 1-1. A thin film is formed by spin coating using a solution obtained by diluting Al4083) (HT-1) with pure water to 70%, and then dried at 200 ° C. for 1 hour to form a first hole transport layer having a thickness of 30 nm. Provided.

This substrate was attached to a vacuum deposition apparatus, and the vacuum chamber was decompressed to 4 × 10 ⁻⁴ Pa. On the first hole transport layer, N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (α-NPD: HT-3) was vapor-deposited with a film thickness of 40 nm as a hole transport material. A second hole transport layer was provided.

  Next, on the second hole transport layer, HOST-30 as a host compound and D-19 as a dopant were deposited in a ratio of HOST-30: D-19 = 100: 6 by 30 nm to provide a light emitting layer.

  Subsequently, 1.0 nm of lithium fluoride was vapor-deposited as an electron injection layer, and 110 nm of aluminum was vapor-deposited as a cathode, respectively, and the organic EL element 2-1 was produced.

<< Production of Organic EL Element 2-2 >>
The same 1st positive hole transport layer and 2nd positive hole transport layer as the organic EL element 2-1 were provided in order on the transparent support substrate which provided the ITO transparent electrode used by preparation of the organic EL element 1-1.

  Next, HOST-30 as a host compound and D-19 as a dopant were deposited on the second hole transport layer at a ratio of HOST-30: D-19 = 100: 6 by 30 nm to provide a light emitting layer.

  Next, 20 nm of ET-B was deposited as an electron transport material on the light emitting layer to provide an electron transport layer.

  Next, 1.0 nm of lithium fluoride was deposited as an electron injection layer, and 110 nm of aluminum was deposited as a cathode to prepare an organic EL element 2-2.

<< Production of Organic EL Elements 2-3 to 2-8 >>
In the production of the organic EL element 2-2, organic EL elements 2-3 to 2-8 were produced in the same manner except that the dopant of the light emitting layer and the electron transport material were changed to the compounds shown in Table 2.

  Here, the organic EL element 2-1 is an organic EL element having no electron transport layer, and the organic EL element 2-2 is an aromatic compound (ET-B) having no nitrogen atom in the electron transport layer. The organic EL element 2-3 contains a tetracoordinate divalent platinum complex (Pt-1) instead of the hexacoordinate tetravalent platinum complex having a carbene ligand as a dopant in the light emitting layer. ).

  The organic EL elements 2-1 to 2-8 produced as described above were evaluated for luminous efficiency, half life, and driving voltage in accordance with the methods described above. The results are shown in Table 2. Here, the measured value of the organic EL element 2-2 is set as 100, and each is shown as a relative value.

  As is clear from the above results, by using a hexacoordinate tetravalent platinum complex having a carbene ligand as the dopant of the light emitting layer, the light emission efficiency was improved and the half life was improved. In addition, by using an aromatic heterocyclic compound having a nitrogen atom in the electron transporting layer, the electron injecting property was improved and the driving voltage was reduced. On the other hand, the organic EL elements 2-1, 2-2, and 2-3 outside the present invention were inferior in any of the characteristics.

Example 3
The structures of compounds other than the exemplified compounds and the compounds used in the examples described below are shown below.

<< Production of Organic EL Element 3-1 >>
The transparent support substrate provided with the ITO transparent electrode used in the production of the organic EL element 1-1 was attached to a vacuum deposition apparatus, and the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa. On the substrate, copper phthalocyanine (HT-4) was deposited as a hole transport material with a film thickness of 30 nm to provide a first hole transport layer.

  On the first hole transport layer, N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (α-NPD: HT-3) was vapor-deposited with a film thickness of 40 nm as a hole transport material. A second hole transport layer was provided.

  Next, HOST-33 as a host compound and P-1 as a dopant were deposited on the second hole transport layer by 30 nm to provide a light emitting layer.

  Next, 20 nm of ET-34 as an electron transport material was deposited on the light emitting layer to provide an electron transport layer.

  Subsequently, 1.0 nm of lithium fluoride was vapor-deposited as an electron injection layer, and 110 nm of aluminum was vapor-deposited as a cathode, respectively, and the organic EL element 3-2 was produced.

<< Production of Organic EL Elements 3-2 to 3-6 >>
In the production of the organic EL element 3-1, organic EL elements 3-2 to 3-6 were respectively produced in the same manner except that the dopant of the light emitting layer and the electron transport material were changed to the compounds shown in Table 3.

  Here, the organic EL device 3-1 uses a carbene pincer tetracoordinate divalent metal complex (P-1) as a dopant of the light emitting layer, and the organic EL device 3-2 is used as an electron transport layer. An aromatic compound having no nitrogen atom (ET-A) is used.

  The organic EL elements 3-1 to 3-6 produced as described above were evaluated for luminous efficiency, half life, and driving voltage in accordance with the above methods. The results are shown in Table 3. Here, the measured value of the organic EL element 3-1 is set to 100, and each is shown as a relative value.

  As is clear from the above results, by using a hexacoordinate tetravalent platinum complex having a carbene ligand as the dopant of the light emitting layer, it becomes difficult to stack in a non-planar manner, the light emission efficiency is improved, and the half life is reduced. Improved. In addition, by using an aromatic heterocyclic compound having a nitrogen atom in the electron transporting layer, the electron injecting property was improved and the driving voltage was reduced. On the other hand, the organic EL device 3-1 outside the present invention using a tetracoordinate divalent platinum complex having a carbene ligand as a dopant and the organic using an aromatic compound containing no nitrogen atom in the electron transport layer. The EL element 3-2 was inferior in any of the characteristics.

Example 4
<< Preparation of White Light-Emitting Organic EL Element 4-1 >>
Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, manufactured by Bayer Co., Ltd., Baytron P) on the transparent support substrate provided with the ITO transparent electrode used in the production of the organic EL element 1-1. A thin film is formed by spin coating using a solution obtained by diluting Al4083) (HT-1) with pure water to 70%, and then dried at 200 ° C. for 1 hour to form a first hole transport layer having a thickness of 30 nm. Provided.

  On the first hole transport layer, poly [N, N′-bis (4-butylphenyl) -N, N′-diphenylbenzidine] (American Dye Source Co., Ltd., ADS-) is used as a hole transport material. 254) A thin film was formed by spin coating using a chlorobenzene solution of (HT-2). It heat-dried at 150 degreeC for 1 hour, and provided the 2nd hole transport layer with a film thickness of 40 nm.

  Next, using a solution obtained by dissolving HOST-56 (100 mg) as a host compound and Ir-18 (3 mg) and Ir-19 (3 mg) as dopants in 10 ml of toluene, spin coating was performed at 2000 rpm for 30 seconds. A thin film was formed. The first light emitting layer was formed by vacuum drying at 60 ° C. for 1 hour.

  Furthermore, on this 1st light emitting layer, the solution which melt | dissolved HOST-92 (100 mg) as a host compound and D-111 (16 mg) as a dopant in 6 ml hexafluoroisopropanol (HFIP) was used on condition of 2000 rpm and 30 seconds. A thin film was formed by spin coating and vacuum dried at 60 ° C. for 1 hour to form a second light emitting layer.

This substrate is fixed to a substrate holder of a vacuum deposition apparatus, the vacuum chamber is depressurized to 4 × 10 ⁻⁴ Pa, and then an ET-35 is deposited on the second light emitting layer to form an electron transport layer having a thickness of 30 nm. Subsequently, lithium fluoride was vapor-deposited to form a cathode buffer layer having a thickness of 0.5 nm, and aluminum was further vapor-deposited to form a cathode having a thickness of 110 nm. Thus, an organic EL element 4-1 was produced. .

  When the produced organic EL element 4-1 was energized, almost white light was obtained, and it was found that it could be used as a lighting device. In addition, it turned out that white light emission is obtained similarly even if it replaces with the other compound of illustration.

(Example 5)
<< Preparation of White Light-Emitting Organic EL Element 5-1 >>
Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, manufactured by Bayer Co., Ltd., Baytron P) on the transparent support substrate provided with the ITO transparent electrode used in the production of the organic EL element 1-1. A thin film is formed by spin coating using a solution obtained by diluting Al4083) (HT-1) with pure water to 70%, and then dried at 200 ° C. for 1 hour to form a first hole transport layer having a thickness of 30 nm. Provided.

  On the first hole transport layer, poly [N, N′-bis (4-butylphenyl) -N, N′-diphenylbenzidine] (American Dye Source Co., Ltd., ADS-) is used as a hole transport material. 254) A thin film was formed by spin coating using a chlorobenzene solution of (HT-2). It heat-dried at 150 degreeC for 1 hour, and provided the 2nd hole transport layer with a film thickness of 40 nm.

  Next, using a solution in which HOST-93 (100 mg) as a host compound, Ir-20 (3 mg) and D-112 (3 mg) as a dopant are dissolved in 10 ml of toluene, spin coating is performed at 2000 rpm for 30 seconds. A thin film was formed. A light emitting layer was formed by vacuum drying at 60 ° C. for 1 hour.

This substrate is fixed to a substrate holder of a vacuum deposition apparatus, and the vacuum chamber is depressurized to 4 × 10 ⁻⁴ Pa. Then, ET-31 is deposited on the light emitting layer to form a first electron transport layer having a thickness of 5 nm. did.

  Next, ET-10 is deposited on the first electron transport layer to form a second electron transport layer having a thickness of 30 nm, and then lithium fluoride is deposited to form a cathode buffer layer having a thickness of 0.5 nm. Then, an organic EL element 5-1 was produced by forming a cathode having a thickness of 110 nm by vapor-depositing aluminum.

  When the produced organic EL element 5-1 was energized, almost white light was obtained, and it was found that it could be used as a lighting device. In addition, it turned out that white light emission is obtained similarly even if it replaces with the other compound of illustration.

(Example 6)
<Production of full-color display device>
(Production of blue light emitting element)
The organic EL element 1-5 of Example 1 was used as a blue light emitting element.

(Production of green light emitting element)
A green light emitting device was produced in the same manner as the organic EL device 1-1 except that Ir-1 was used as a green light emitting dopant.

(Production of red light emitting element)
A red light emitting device was produced in the same manner as the organic EL device 1-1 except that Ir-9 was used as a red light emitting dopant.

  Each of the red, green, and blue light emitting organic EL elements produced above was juxtaposed on the same substrate to produce an active matrix type full color display device having the form as shown in FIG. 1, and FIG. Only the schematic diagram of the display section A of the display device is shown. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. Thus, a full color display device was produced by juxtaposing the red, green, and blue pixels appropriately.

  It was found that by driving the full-color display device, a clear full-color moving image display having high luminance, high durability, and clearness can be obtained.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with a transparent electrode

Claims (14)

An organic electroluminescent device having a light emitting layer and an electron transport layer adjacent to the cathode side of the light emitting layer between an anode and a cathode,
The light-emitting layer contains a hexacoordinate tetravalent platinum complex having a polydentate ligand (except for the case where it is a dicarbene transition metal complex represented by the following general formula (A)) ,
At least one of the polydentate ligands is a carbene ligand having a site coordinated to a platinum atom,
An organic electroluminescence device, wherein the electron transport layer adjacent to the cathode side of the light emitting layer contains a compound having an aromatic heterocycle containing a nitrogen atom as a skeleton.

Formula (A)
Wherein Pt represents a platinum atom and can be in any oxidation state; K represents an uncharged monodentate or bidentate ligand; L represents a monodentate or bidentate monoanionic or dianionic M represents an integer of 0 to 5; o represents an integer of 0 to 5; n represents an integer of 1 to 3; p represents the number of charges of the complex; Represents an integer of ˜4; W− represents a monoanionic counterion; m, o, n, and p represent the oxidation state and coordination number of a platinum atom that is Pt, or the charge of a ligand Y1, Y2, Y3 and Y4 are each independently hydrogen, an alkyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkenyl group; Represents an alkynyl group or an alkoxy group, and these groups are substituted Y 1 and Y 2, Y 2 and Y 3, and Y 3 and Y 4 are each independently a part of them joined together to form at least two atoms between nitrogen atoms. A saturated or unsaturated ring structure, and one or more atoms of these ring structures may be substituted with an alkyl group or an aryl group (these substituents may be further substituted). These ring structures may further form one or more ring structures; each of R 1 and R 2 independently represents hydrogen, an alkyl group, a cycloalkyl group, A heterocycloalkyl group, an aryl group, an aralkyl group, a heteroaryl group, an alkenyl group, an alkynyl group or an alkoxy group, and these groups may be substituted or unsubstituted.) The organic electroluminescence device according to claim 1, wherein the hexacoordinate tetravalent platinum complex is a compound represented by the following general formula (I).

(In general formula (I), Pt represents a platinum atom having a coordination number of 6 and tetravalent. Ring A represents an aromatic ring formed together with Y ₁ and a carbon atom, and further has a substituent. The substituents may be bonded to each other to form a ring, Y ₁ represents a carbon atom or a nitrogen atom, and X _{1 to} X ₄ represent a 5-membered aromatic together with a carbene carbon atom coordinated to Pt. Is a group of atoms forming a group heterocycle, and represents a carbon atom, C—R ₁ , nitrogen atom, N—R ₁ , oxygen atom or sulfur atom, and at least one represents a nitrogen atom or N—R _{1. 1} represents a hydrogen atom or a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. And the two L ₁ may be the same or different from each other.)   The organic electroluminescence device according to claim 2, wherein the ring A in the general formula (I) represents a 5-membered or 6-membered aromatic ring. The organic electroluminescence device according to claim 2 or 3, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (II).

(In General Formula (II), Pt represents a tetravalent platinum atom having a coordination number of 6. Y ₂ to Y ₆ are an atomic group that forms a 6-membered aromatic ring together with a carbon atom coordinated to Pt. And represents a carbon atom, C—R ₂ or a nitrogen atom, wherein X ₅ and X ₆ are a group of atoms forming a 5-membered aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and C—R ₃ or nitrogen R ₂ and R ₃ represent a hydrogen atom or a substituent, R ₄ represents a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, and m and n represent an integer of 1 or more. And satisfies the relational expression m + n = 3.When m is 2, the two L ₁ may be the same or different from each other.) The organic electroluminescent device according to claim 4, wherein the compound represented by the general formula (II) is a compound represented by the following general formula (III).

(In General Formula (III), X ₇ and X ₈ are carbon atoms having a single bond or a double bond, and may have a substituent. R _{6 to} R ₉ represent a hydrogen atom or a substituent. , R ₅ represents a substituent, L ₁ represents an auxiliary ligand coordinated to Pt, m and n represent an integer of 1 or more, and satisfy the relational expression m + n = 3. Two L ₁ may be the same or different from each other.) 2. The organic electro of claim 1, wherein the hexacoordinate tetravalent platinum complex is a platinum complex having at least one tridentate carbene ligand represented by the following general formula (IV): Luminescence element.

(In general formula (IV), Pt represents a tetravalent platinum atom having a coordination number of 6. Ring B, ring C and ring D represent an aromatic ring, at least one of which is an aromatic heterocycle containing a nitrogen atom. Ring B, Ring C and Ring D may have a substituent, and these substituents may be bonded to each other to form a ring V, W and Z are carbon atoms, carbene A carbon atom or a nitrogen atom, at least one of which is a carbene carbon atom, L ₁ represents an auxiliary ligand coordinated to Pt, and p represents 1 or 2. When p is 2, two L ₁ may be the same as or different from each other.   In the said general formula (IV), both V and Z are carbene carbon atoms, or only W is a carbene carbon atom, The organic electroluminescent element of Claim 6 characterized by the above-mentioned.   The compound having an aromatic heterocycle containing a nitrogen atom contained in an electron transport layer adjacent to the cathode side of the light emitting layer as a skeleton is a compound having a pyridine ring as a skeleton. Item 8. The organic electroluminescence device according to any one of Items 7 to 7.   The organic electroluminescence device according to claim 8, wherein the compound having the pyridine ring as a skeleton is a pyridine derivative or an azacarbazole derivative. The organic electroluminescence device according to claim 9, wherein the compound having the pyridine ring as a skeleton is an azacarbazole derivative. The organic electroluminescence element, an organic electroluminescent device as claimed in any one of claims 1 to 10, characterized in that it comprises a light-emitting layer of the multiple layers. The organic electroluminescence device according to any one of claims 1 to 11, wherein the organic electroluminescence device contains two or more kinds of light-emitting materials and the emission color is white. A display device comprising the organic electroluminescence element according to any one of claims 1 to 12 . An illuminating device comprising the organic electroluminescence element according to any one of claims 1 to 12 .

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