JP2005170851A - Metal coordinated compound and organic light-emitting device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphorescence-emitting material which has high luminous efficiency, maintains high luminance, and enables red light emission, and a light-emitting device and a display device which use the phosphorescence-emitting material. <P>SOLUTION: These metal coordinated compounds are specific coordinated compound including, for example, tetrakis(7,8-dihydro-1-aza-benzo[4,5]cyclohepta[1,2,3-de]naphthalene-C<SP>12</SP>,N)(μ-dichloro)diiridium (III), bis(7,8-dihydro-1-aza-[4,5]cyclohepta[1,2,3-de]naphthalene-C<SP>12</SP>,N)(acetylacetonato)iridium (III), and tris(7,8-dihydro-1-aza-benzo[4,5]cyclohepta[1,2,3-de]naphthalene-C<SP>12</SP>,N)iridium (III). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel metal coordination compound, an organic light-emitting device (also referred to as an organic electroluminescence device or an organic EL device) using the metal coordination compound, and an image display device using the organic light-emitting device.

  In the past, there has been an example in which an organic light emitting element emits light by applying a voltage to an anthracene vapor deposition film (Non-patent Document 1). In recent years, however, it has become easier to increase the area compared to inorganic light-emitting elements, can achieve a desired color by developing various new materials, and can be driven at a low voltage, resulting in higher response speed. As a light-emitting element with high efficiency and high efficiency, applied research for device development, including material development, has been vigorously conducted.

  For example, as detailed in Non-Patent Document 2, an organic EL element generally has a configuration in which an upper and lower two layers of electrodes are formed on a transparent substrate, and an organic material layer including a light emitting layer is formed therebetween. .

  For the light-emitting layer, an aluminum quinolinol complex having electron transport properties and light-emitting properties, and representative examples include Alq3 shown below. For the hole transport layer, for example, a material having an electron donating property such as a triphenyldiamine derivative, typically α-NPD shown below, is used.

  These elements exhibit electrical rectification properties. When an electric field is applied between the electrodes, electrons are injected from the cathode into the light emitting layer, and holes are injected from the anode. The injected holes and electrons recombine in the light emitting layer to generate excitons, which emit light when they transit to the ground state. In this process, the excited state has an excited singlet state and a triplet state. The transition from the former to the ground state is called fluorescence, and the transition from the latter is called phosphorescence. Certain substances are called singlet excitons and triplet excitons, respectively.

  Many of the organic light emitting devices that have been studied so far utilize fluorescence when transitioning from a singlet exciton to a ground state. On the other hand, recently, devices using phosphorescence emission via triplet excitons have been studied (Non-Patent Documents 3 and 4). In these documents, a structure in which four organic layers sandwiched between electrodes are laminated is mainly used, and materials used are a carrier transport material and a phosphorescent material described below.

In addition, the abbreviation of each material is as follows.
Alq3: Aluminum-quinolinol complex α-NPD: N4, N4′-Di-naphthalen-1-yl-N4, N4′-diphenyl-biphenyl-4, 4′-diamine
CBP: 4,4′-N, N′-dicarbazole-biphenyl
BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline
PtOEP: platinum-octaethylporphyrin complex Ir (ppy) 3: iridium-phenylpyrimidine complex

  Both non-patent documents 3 and 4 have high efficiency. The device is phosphorescent with α-NPD as the hole transport layer, Alq3 as the electron transport layer, BCP as the exciton diffusion preventing layer, and CBP as the light emitting layer as host materials. It was an element using a light emitting material in which PtOEP or Ir (ppy) 3 was dispersed and mixed at a concentration of about 6%.

  The reason why phosphorescent light-emitting materials are particularly attracting attention is that high luminous efficiency can be expected in principle for the following reasons. That is, excitons generated by carrier recombination are composed of singlet excitons and triplet excitons, and the probability is 1: 3. Conventional organic EL devices have used fluorescence emission, but in principle, the emission yield is 25% of the number of excitons generated, which is the upper limit. However, if phosphorescence generated from triplet excitons is used, a yield of at least three times is expected in principle, and the transition due to intersystem crossing from singlet to triplet, which is higher in energy, is considered. In principle, a light emission yield of 100%, which is 4 times, can be expected.

  However, the organic light emitting device using phosphorescence emission is generally required to be further improved with respect to deterioration of light emission efficiency and device stability, like the fluorescent light emitting device. Although details of the cause of this deterioration are unclear, the present inventors consider the following as based on the mechanism of phosphorescence emission.

When the organic light emitting layer is composed of a carrier transporting host material and a phosphorescent guest, the main process from triplet exciton to phosphorescence is composed of the following several processes.
1. 1. Transport of electrons and holes in the light emitting layer 2. Host exciton generation 3. Excitation energy transfer between host molecules 4. Excitation energy transfer from host to guest 5. Triplet exciton generation of guest Ground state transition and phosphorescence emission from guest triplet exciton

  The desired energy transfer and light emission in each process is a competitive reaction with various energy deactivation processes.

  Needless to say, in order to increase the light emission efficiency of the organic light emitting device, the emission quantum yield of the light emission center material itself is increased.

  In particular, in a phosphorescent material, it is generally considered that the lifetime of the triplet exciton is longer than that of the singlet exciton by three orders of magnitude or more. In other words, since the energy is kept in an excited state for a long time, there is an increased probability that a deactivation process will occur due to reactions with surrounding substances and the formation of multimers between excitons, resulting in changes in the substance. The present inventors believe that the life is likely to be deteriorated.

  As a light emitting material used for a phosphorescent light emitting device, a compound having high efficiency light emission and high stability is desired. In particular, since the lifetime in the energy excited state is long, it is strongly desired that energy loss is unlikely to occur, and that it is chemically stable and the device lifetime is extended. Furthermore, since there has been no material capable of producing pure red in the past, there has been a strong expectation for a red light-emitting material, particularly in producing a full-color display element.

Thin Solid Films, 94 (1982) 171 Macromol. Symp. 125,1-48 (1997) Improve energy transfer in electrophoretic device (DF O'Brien et al., Applied Physics Letters Vol 74, No3 p422 (1999)) Very high-efficiency green organic light-emitting devices basd on electrophorescence (MA Baldo et al., Applied Physics Letters Vol 75, No1 p4)

  Accordingly, an object of the present invention is to provide a phosphorescent material that has high luminous efficiency, maintains high luminance for a long period of time, and can emit red light, and a light emitting element and a display device using the phosphorescent light emitting material. .

  The present inventors have found that a specific metal coordination compound emits light with high efficiency in a red region near 600 nm, maintains high luminance for a long period of time, and has little deterioration in energization, thereby completing the present invention.

  That is, the metal coordination compound of the present invention is characterized by having at least one partial structure represented by the following general formula (1).

ML (1)
[Wherein the partial structure ML is represented by the following general formula (2), M is a metal atom of Ir, Pt, Rh, Re, Cu, W or Pd, C is a carbon atom, and A is a carbon atom A cyclic group which may have a substituent bonded to the metal atom M via N is a nitrogen atom, and B is a cyclic group which may have a substituent bonded to the metal atom M through the nitrogen atom. The cyclic group B is bonded to the cyclic group A through a single bond and X.

  The following general formula (3) including the cyclic group B in the general formula (2)

Is represented by the following general formula (4).

In the general formula (4), E _{1 to} E ₅ each represent a nitrogen atom or a CH group, and the hydrogen atom of the CH group may be replaced with a substituent. X is a linear or branched alkylene group having 2 to 10 carbon atoms (one or two or more methylene groups in the alkylene group are —O—, —S—, —CO—, —CO -O-, -O-CO-, -CH = CH-, -C≡C- may be substituted, and a hydrogen atom in the alkylene group may be substituted by a fluorine atom). .

The substituents of E _{1 to} E ₅ and cyclic group A are a halogen atom, a cyano group, a nitro group, a di-substituted amino group {the substituents may each independently have a phenyl group or a naphthyl group. (The substituent is a halogen atom, a methyl group or a trifluoromethyl group) or a linear or branched alkyl group having 1 to 8 carbon atoms, and the hydrogen atom in the alkyl group is a fluorine atom. May be substituted. }, A trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear or branched group having 1 to 20 carbon atoms An alkyl group {one or two or more non-adjacent methylene groups in the alkyl group are -O-, -S-, -CO-, -CO-O-, -O-CO-, -CH = CH-, -C≡C- may be substituted, and one or more methylene groups in the alkyl group may have a substituent, a divalent aromatic ring group (the substituent is a halogen atom) , A cyano group, a nitro group, a trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear chain having 1 to 20 carbon atoms Or a branched alkyl group (if one of the alkyl groups Two or more non-adjacent methylene groups are replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—. Or a hydrogen atom in the alkyl group may be substituted with a fluorine atom.)), Or a hydrogen atom in the alkyl group may be substituted with a fluorine atom. Good. }. Further, adjacent substituents may be bonded to form a ring structure. ]

  The organic light-emitting device of the present invention is an organic light-emitting device comprising a light-emitting portion containing at least one organic compound between a pair of electrodes provided on a substrate, wherein the organic compound contains the metal coordination compound. It is characterized by including.

  An image display apparatus according to the present invention includes the organic light emitting element and means for supplying an electric signal to the organic light emitting element.

  A light-emitting element using the metal coordination compound of the present invention as an emission center material is an excellent element capable of not only high-efficiency light emission but also high luminance for a long period of time and a longer wavelength. In addition, the light-emitting element of the present invention is also excellent as a display element.

  First, the metal coordination compound of the present invention will be described.

  The metal coordination compound of the present invention has at least one partial structure represented by the general formula (1), and examples thereof include those represented by the following general formulas (5) and (12).

MLm L'n (5)
[Wherein, M is a metal atom of Ir, Pt, Rh or Pd, and L and L ′ represent different bidentate ligands. m is 1 or 2 or 3, and n is 0 or 1 or 2. However, m + n is 2 or 3. The partial structure ML′n is represented by the following general formula (6), (7), (8) or (9).

  In general formulas (6), (7), and (9), N and C are nitrogen and a carbon atom. A ′ and A ″ are cyclic groups which may have a substituent bonded to the metal atom M via a carbon atom, and B ′, B ″ and B ′ ″ are each a metal atom via a nitrogen atom. A cyclic group which may have a substituent bonded to M, and the cyclic group B ′ is bonded to the cyclic group A ′ via a single bond and X ′, and the cyclic group A ″ and the cyclic group B ″ Are linked by a covalent bond.

  The following general formula (10) containing the cyclic group B ′ in the general formula (6)

Is represented by the following general formula (11).

In General Formula (11), E ₁ ′ to E ₅ ′ each represent a nitrogen atom or a CH group, and the hydrogen atom of the CH group may be replaced with a substituent. X ′ represents a linear or branched alkylene group having 2 to 10 carbon atoms (one or two or more non-adjacent methylene groups in the alkylene group are —O—, —S—, —CO—, — CO—O—, —O—CO—, —CH═CH—, —C≡C— may be substituted, and a hydrogen atom in the alkylene group may be substituted with a fluorine atom). is there.

The substituents of the cyclic groups A ′, A ″, B ″, B ′ ″ and E ₁ ′ to E ₅ ′ are halogen atoms, cyano groups, nitro groups, disubstituted amino groups {the substituents are each independently An optionally substituted phenyl group, naphthyl group (the substituent is a halogen atom, a methyl group or a trifluoromethyl group), or a linear or branched alkyl having 1 to 8 carbon atoms; A hydrogen atom in the alkyl group may be substituted with a fluorine atom. }, A trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear or branched structure having 1 to 20 carbon atoms An alkyl group in which one or two or more methylene groups in the alkyl group are —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— , -C≡C-, and one or two or more methylene groups in the alkyl group may be substituted with a divalent aromatic ring group (the substituent is a halogen atom) An atom, a cyano group, a nitro group, a trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a straight chain having 1 to 20 carbon atoms, A chain or branched alkyl group (including one of the alkyl groups) Or two or more non-adjacent methylene groups are replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—. And a hydrogen atom in the alkyl group may be substituted with a fluorine atom.)), And a hydrogen atom in the alkyl group may be substituted with a fluorine atom. Also good. }. Further, adjacent substituents may be bonded to form a ring structure.

  In the general formula (8), E, G and J are each independently a linear or branched alkyl group having 1 to 20 carbon atoms {one or two or more methylene groups not adjacent to each other in the alkyl group] May be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—, and 1 in the alkyl group. One or two or more methylene groups may have a divalent aromatic ring group (the substituent is a halogen atom, a cyano group, a nitro group, a trialkylsilyl group (the alkyl group is independently A straight-chain or branched alkyl group having 1 to 8 carbon atoms.), A straight-chain or branched alkyl group having 1 to 20 carbon atoms (one or two adjacent groups in the alkyl group). One or more methylene groups are —O—, —S—, —CO—, —CO—. -, -O-CO-, -CH = CH-, -C≡C- may be substituted, and a hydrogen atom in the alkyl group may be substituted by a fluorine atom). The adjacent substituents may be bonded to form a ring structure.), And a hydrogen atom in the alkyl group may be substituted with a fluorine atom. } Or a di-substituted amino group {the substituents may each independently have a phenyl group, a naphthyl group (the substituent is a halogen atom, a methyl group or a trifluoromethyl group) or carbon. A linear or branched alkyl group having 1 to 8 atoms, and a hydrogen atom in the alkyl group may be substituted with a fluorine atom. }. J may be a hydrogen atom. ]

[Wherein Cl means a chlorine atom, and M ′ is Ir or Rh. ]

The metal coordination compound represented by the general formula (5) preferably has a partial structure ML′n represented by the general formula (6). N is preferably 0 or 1, and more preferably 0. In addition, the phenylene group, naphthylene group, thienylene group, fluorenylene group, thianaphthylene group, acenaphthylene group, anthranylene group, phenanthrenylene group, pyrenylene group, which is an aromatic ring group that the cyclic group A ′ may have a substituent. , A carbazolinylene group (one or two of the CH groups constituting the aromatic ring group may be replaced by a nitrogen atom), and the cyclic group A ″ may have a substituent Phenyl group, naphthyl group, thienyl group, fluorenyl group, thianaphthyl group, acenaphthyl group, anthranyl group, phenanthrenyl group, pyrenyl group, carbazolyl group (one or two of the CH groups constituting the aromatic ring group are nitrogen It may be replaced by an atom.), And the phenylene group in which the cyclic group A ′ may have a substituent is preferable. More preferably, the phenylene group, which may have a substituent, is adjacent to the cyclic group B ′ (1-position) next to the position (1-position) (6-position) via X ′. It is further preferable that the cyclic group B ′ is bonded to the cyclic group B ′. The cyclic groups A ′, A ″, B ″, B ′ ″ and E ₁ ′ to E ₅ ′ are each unsubstituted, halogen atom, carbon A linear or branched alkyl group having 1 to 20 atoms (one or two or more non-adjacent methylene groups in the alkyl group are -O-, -S-, -CO-, -CH = CH- , -C≡C-, and one or two or more methylene groups in the alkyl group may be substituted with a divalent aromatic ring group (the substituent is a halogen atom) An atom, a linear or branched alkyl group having 1 to 20 carbon atoms (one or adjacent to the alkyl group) Or two or more methylene groups may be replaced with -O-, and a hydrogen atom in the alkyl group may be replaced with a fluorine atom). A hydrogen atom in the alkyl group may be substituted with a fluorine atom. } It is preferable to have a substituent selected from.

The metal coordination compound of the present invention includes a phenylene group, a naphthylene group, a thienylene group, a fluorenylene group, a thianaphthylene group, an acenaphthylene group, an anthranylene group, a phenol group whose cyclic group A is an aromatic ring group which may have a substituent. It is preferably selected from a nanthrenylene group, a pyrenylene group, and a carbazolinylene group (one or two of the CH groups constituting the aromatic ring group may be replaced by a nitrogen atom), and the cyclic group A is a substituent. It is more preferable that it is a phenylene group which may have a substituent, which is adjacent to the position (1-position) where the phenylene group which may have a substituent is bonded to the cyclic group B by a single bond (6 More preferably, it is bonded to the cyclic group B via X at the -position). In addition, each of the cyclic groups A and E _{1 to} E ₅ is unsubstituted, a halogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms {one of the alkyl groups or two not adjacent to each other] The above methylene groups may be replaced by —O—, —S—, —CO—, —CH═CH—, —C≡C—, and one or more methylene groups in the alkyl group Is a divalent aromatic ring group which may have a substituent (the substituent is a halogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms (one or adjacent to the alkyl group) Or two or more methylene groups may be replaced with -O-, and a hydrogen atom in the alkyl group may be replaced with a fluorine atom). The hydrogen atom in the alkyl group is a fluorine atom. It may be conversion. } It is preferable to have a substituent selected from. M is preferably iridium.

  The metal coordination compound of the present invention emits phosphorescent light, and the lowest excited state is a triplet state MLCT * (Metal-to-Land charge transfer) excited state or π- * excited state. it is conceivable that. Phosphorescence emission occurs when transitioning from these states to the ground state.

  The phosphorescent quantum yield of the luminescent material of the present invention was as high as 0.10 to 0.83, and the phosphorescence lifetime was as short as 0.1 to 12 μsec.

  A short phosphorescence lifetime is one condition for increasing luminous efficiency because there is little energy loss when an EL element is formed. That is, when the phosphorescence lifetime is long, the number of molecules in the triplet excited state waiting for light emission increases, and there is a problem that the light emission efficiency decreases particularly at a high current density. The metal coordination compound of the present invention is a material suitable for a light-emitting material of an EL element having a high phosphorescence quantum yield and a short phosphorescence lifetime.

  In the metal coordination compound of the present invention, the emission wavelength can be adjusted by introducing an electron-withdrawing substituent or an electron-donating substituent. In addition, by introducing substituents with large electronic effects such as alkoxy groups and polyfluorinated alkyl groups, and sterically bulky substituents, it is possible to simultaneously control the emission wavelength and suppress concentration quenching due to intermolecular interactions. It becomes. In addition, it is considered that the introduction of a sterically bulky substituent having a small electronic effect such as an alkyl group can suppress concentration quenching without changing the emission wavelength. Further, by replacing one or two CH groups constituting the aromatic ring of the metal coordination compound of the present invention with a nitrogen atom, the emission wavelength can be adjusted without introducing a substituent.

  Also from the above viewpoints, the metal coordination compound of the present invention is suitable as a light emitting material for an organic EL device.

  Further, the thermal stability of the material is important for the constituent organic material of the organic EL element. This strongly affects the production stability at the time of element creation and the element stability at the time of energization operation. When creating an organic EL element, the creation process may be a process using vacuum deposition, spin coating, or inkjet. In particular, in the vacuum deposition method, the organic material is deposited on the substrate by being sublimated or evaporated by resistance heating, so that there is time to be exposed to a high temperature. Therefore, the thermal stability of the constituent material is very important. The metal coordination compound of the present invention has high thermal stability and is also a material suitable for vacuum deposition.

  When the metal coordination compound of the present invention is used as a light emitting material, it may be dispersed in other materials, or the metal coordination compound of the present invention may be laminated at 100% without using other materials. .

  Hereinafter, specific structural formulas of the metal coordination compounds used in the present invention are shown in Tables 1 to 15. Tables 1 to 11 are specific examples of the compound represented by the general formula (5) (Tables 1 to 4 show the case where n = 0, Tables 5 and 6 show that the partial structure ML′n is the general formula (6)) When the partial structure ML′n is represented by the general formula (7), Tables 9 and 8 are represented when the partial structure ML′n is represented by the general formula (9). Table 12 to Table 15 are specific examples of the compound represented by the general formula (12), when the structure ML′n is represented by the general formula (8). However, these are merely representative examples, and the present invention is not limited thereto.

  In these tables, the abbreviations used for A and A ′ represent the structures shown below.

  The abbreviations used for X and X ′ represent the structures shown below.

  The abbreviations used for A ″ represent the structures shown below.

  The abbreviations used for B ″ and B ′ ″ represent the structures shown below.

  An example of the synthesis route of the metal coordination compound of the present invention is shown below using an iridium coordination compound as an example.

  In addition, the measuring method of the physical-property value in this invention is as follows.

(1) Method for determining phosphorescence and fluorescence The method for determining phosphorescence was determined by whether or not oxygen was lost. When the compound was dissolved in chloroform and irradiated with light to the oxygen-substituted solution and the nitrogen-substituted solution, and the photoluminescence was compared, the oxygen-substituted solution showed almost no light emission derived from the compound, but was substituted with nitrogen. Solutions can be distinguished by the fact that photoluminescence can be confirmed. The compounds of the present invention are all confirmed to be phosphorescent by this method unless otherwise specified.

(2) Phosphorescence yield The method for obtaining the phosphorescence yield used in the present invention is given by the following equation.
Φ (sample) / Φ (st) = [Sem (sample) / Iabs (sample)] / [Sem (st) / Iabs (st)]
Iabs (st): Absorption coefficient Sem (st) at the excitation wavelength of the standard sample: Emission spectrum area intensity when excited at the same wavelength Iabs (sample): Absorption coefficient Sem (sample) at the excitation wavelength of the target compound : Emission spectrum area intensity when excited at the same wavelength

  The phosphorescence quantum yield mentioned here is shown by relative evaluation with Φ of Ir (ppy) 3 as the standard 1.

(3) Phosphorescence lifetime The method for measuring the phosphorescence lifetime is as follows.

  First, the compound was dissolved in chloroform and spin-coated on a quartz substrate with a thickness of about 0.1 μm. This was irradiated with a pulse of nitrogen laser light having an excitation wavelength of 337 nm at room temperature using a light emission lifetime measuring device manufactured by Hamamatsu Photonics. The decay time of the emission intensity after the excitation pulse ended was measured.

When the initial emission intensity is I ₀ , the emission intensity I after t seconds is defined by the following equation using the emission lifetime τ.

I = I ₀ exp (−t / τ)

  Next, the organic light emitting device of the present invention will be described.

  The organic light-emitting device of the present invention is an organic light-emitting device comprising a light-emitting portion containing at least one organic compound between a pair of electrodes provided on a substrate, wherein the organic compound contains the metal coordination compound. It is preferable that phosphorescence is emitted by applying a voltage between the electrodes, and the emission color of the phosphorescence is more preferably red.

  As shown in FIG. 1, in general, an organic EL element is formed on a transparent substrate 15 with a transparent electrode 14 having a film thickness of 50 to 200 nm, a plurality of organic film layers, and a metal electrode 11 so as to sandwich this. Is formed.

  FIG. 1A shows an example in which the organic layer is composed of the light emitting layer 12 and the hole transport layer 13. As the transparent electrode 14, ITO or the like having a large work function is used to facilitate hole injection from the transparent electrode 14 into the hole transport layer 13. The metal electrode 11 is made of a metal material having a small work function, such as aluminum, magnesium, or an alloy using them, to facilitate electron injection into the organic layer.

  For the light emitting layer 12, the compound of the present invention is used. For the hole transporting layer 13, for example, a material having an electron donating property such as a triphenyldiamine derivative, a representative example is α-NPD shown in Chemical Formula 1 is appropriately used. Can be used.

  The element having the above configuration exhibits electrical rectification. When an electric field is applied so that the metal electrode 11 serves as a cathode and the transparent electrode 14 serves as an anode, electrons are injected from the metal electrode 11 into the light emitting layer 12, and the transparent electrode 15. Holes are injected. The injected holes and electrons recombine in the light emitting layer 12 to generate excitons and emit light. At this time, the hole transport layer 13 serves as an electron blocking layer, and the recombination efficiency at the interface between the light emitting layer 12 and the hole transport layer 13 is increased, and the light emission efficiency is increased.

  Further, in FIG. 1B, an electron transport layer 16 is provided between the metal electrode 11 and the light emitting layer 12 in FIG. Luminous efficiency is increased by separating the light emitting function and the electron and hole transporting function to form a more effective carrier blocking structure. As the electron transport layer 16, for example, an oxadiazole derivative or the like can be used.

  Further, as shown in FIG. 1C, a four-layer structure including a hole transport layer 13, a light emitting layer 12, an exciton diffusion preventing layer 17, an electron transport layer 16, and a metal electrode 11 from the transparent electrode 14 side that is an anode. It is also a desirable form.

  The organic light-emitting device of the present invention can be applied to products that require energy saving and high luminance. Application examples include light sources for display devices / illuminators and printers, backlights for liquid crystal display devices, and the like. As a display device, energy saving, high visibility, and a lightweight flat panel display are possible. In addition, as a light source of a printer, a laser light source unit of a laser beam printer that is widely used at present can be replaced with the light emitting element of the present invention. With respect to the lighting device and the backlight, the energy saving effect according to the present invention can be expected.

  In application to a display, a driving method using a thin film transistor (abbreviated as TFT) driving circuit which is an active matrix method can be considered.

  Hereinafter, an example using an active matrix substrate in the element of the present invention will be briefly described with reference to FIGS.

  FIG. 2 schematically shows an example of the configuration of a panel provided with EL elements and driving means. A scanning signal driver, an information signal driver, and a current supply source are arranged on the panel, and are connected to a gate selection line, an information signal line, and a current supply line, respectively. A pixel circuit shown in FIG. 3 is arranged at the intersection of the gate selection line and the information signal line. The scanning signal driver includes gate selection lines G1, G2, G3. . . Gn is sequentially selected, and an image signal is applied from the information signal driver in synchronization therewith.

  Next, the operation of the pixel circuit will be described. In this pixel circuit, when a selection signal is applied to the gate selection line, the TFT1 is turned on, an image signal is supplied to Cadd, and the gate potential of the TFT2 is determined. A current is supplied to the EL element from the current supply line according to the gate potential of the TFT 2. Since the gate potential of the TFT 2 is held at Cadd until the next scanning selection of the TFT 1, the EL element continues to flow until the next scanning is performed. This makes it possible to always emit light for one frame period.

  FIG. 4 is a schematic diagram showing an example of a cross-sectional structure of a TFT substrate used in the present invention. A p-Si layer is provided on the glass substrate, and necessary impurities are doped into the channel, drain, and source regions, respectively. A gate electrode is provided thereon via a gate insulating film, and a drain electrode and a source electrode connected to the drain region and the source region are formed. An insulating layer and an ITO electrode as a pixel electrode are stacked on these, and the ITO and the drain electrode are connected by a contact hole.

  The present invention is not particularly limited to switching elements, and can be easily applied to single crystal silicon substrates, MIM elements, a-Si type, and the like.

  A multilayer or single-layer organic EL layer / cathode layer is sequentially laminated on the ITO electrode to obtain an organic EL display panel. By driving a display panel using the light-emitting material of the present invention for the light-emitting layer, stable display can be performed with good image quality and long-time display.

  The present invention will be specifically described below with reference to examples.

  <Example 1> (Synthesis of Exemplified Compound Nos. 256, 231 and 1)

  Tokyo Chemical Industry Dibenzosuberon (A) 95.0 g (456 mmole) and toluene 950 ml were dissolved in a 3 L three-necked flask, and 182.3 g (1369 mmole) of Tokyo Chemical Industry aminoacetal was added while stirring at room temperature. Thereafter, 64.7 g (456 mmole) of boron trifluoride / diethyl ether complex was added dropwise over 10 minutes while stirring at room temperature. Thereafter, the temperature was raised and reflux stirring was performed for 32 hours. The reaction product was allowed to cool to room temperature, and 950 ml of 10% aqueous sodium carbonate solution was added for liquid separation. The organic layer was washed with water until neutrality, and the solvent was evaporated to dryness. The residue was purified by silica gel column chromatography (eluent: toluene / tetrahydrofuran: 20/1) and (2,2-diethoxy-ethyl)-(10,11-dihydro-dibenzo [ad] cycloheptene-5-ylidene) -amine. 47.7 g (yield 32.3%) of an oily product of (B) was obtained.

  (B) 38.5 g (119 mmole) and polyphosphoric acid 178 g (25.0 mmole) were placed in a 300 ml three-necked flask, and the reaction temperature was maintained at 100 ° C. to 102 ° C., and the mixture was heated and stirred with a mechanical stirrer for 3 hours 30 minutes. The reaction product was allowed to cool, 100 ml of water and 250 ml of methyl t-butyl ether were added and stirred, and 200 ml of 28% aqueous ammonia was slowly added dropwise to separate the layers. The organic layer was washed with water until neutrality, and the solvent was evaporated to dryness. The residue was purified by silica gel column chromatography (eluent: toluene / tetrahydrofuran: 50/1), recrystallized from ethanol, and 7,8-dihydro-1-aza-benzo [4,5] cyclohepta [1,2,3. -De] 14.0 g (yield 50.9%) of naphthalene (C) crystals were obtained.

In a 300 ml three-necked flask, 1.24 g (3.30 mmole) of iridium (III) chloride trihydrate manufactured by N.E. Catcat Co., Ltd., 1.68 g (7.26 mmole) of (C), 90 ml of ethoxyethanol and water 30 ml was added and stirred at room temperature for 30 minutes under a nitrogen stream, and then refluxed for 24 hours. The reaction product was cooled to room temperature, and the precipitate was collected by filtration, washed with water, and then washed with ethanol. Dried under reduced pressure at room temperature, tetrakis (7,8-dihydro-1-aza - benzo [4,5] cyclohepta [1, 2, 3-de] naphthalene -C ^12, N) (.mu.-dichloro) diiridium (III ) (D) (Exemplary Compound No. 256) 1.60 g (yield 70.4%) of a red powder was obtained. 1376.3, which is M ⁺ , of this compound was confirmed by MALDI-TOF MS (matrix-assisted ionization-time-of-flight mass spectrometry).

A 200 ml three-necked flask was charged with 55 ml of ethoxyethanol, 1.60 g (1.16 mmole) of (D), 0.35 g (2.10 mmole) of acetylacetone and 1.69 g (15.9 mmole) of sodium carbonate, For 1 hour and then refluxed for 15 hours. The reaction product is ice-cooled, the precipitate is collected by filtration, washed successively with water and ethanol, and bis (7,8-dihydro-1-aza-benzo [4,5] cyclohepta [1,2,3-de]. to obtain a red powder 1.30g of naphthalene -C ^12, N) (acetylacetonato) iridium (III) (E) (exemplary compound No.231) (74.5% yield). 752.2 which is M ^<+> of this compound was confirmed by MALDI-TOF MS.

(C) 0.58 g (2.5 mmole), (E) 0.75 g (1.0 mmole) and glycerol 50 ml were placed in a 100 ml three-necked flask, and the mixture was heated and stirred at about 180 ° C. for 8 hours under a nitrogen stream. The reaction product was cooled to room temperature and poured into 300 ml of 1N hydrochloric acid, and the precipitate was collected by filtration and washed successively with water and ethanol. This precipitate was purified by silica gel column chromatography using chloroform as an eluent, and tris (7,8-dihydro-1-aza-benzo [4,5] cyclohepta [1,2,3-de] naphthalene-C ¹² , N) 0.13 g (yield 14.7%) of red powder of iridium (III) (F) (Exemplary Compound No. 1) was obtained. MALDI-TOF MS confirmed 877.2 as M ⁺ of this compound. Λmax of the emission spectrum of the toluene solution of this compound was 625 nm, and the quantum yield was 0.79 when Ir (ppy) 3 = 1.0.

<Example 2> (Synthesis of Exemplified Compound Nos. 314, 235 and 59)
The following compounds were synthesized in the following yields in the same manner as in Example 1 except that dibenzosuberone (G) was used instead of dibenzosuberone (A) in Example 1.

<Examples 3 to 8, Comparative Example 1>
A device having three organic layers as shown in FIG.

ITO (transparent electrode 14) having a thickness of 100 nm was patterned on a glass substrate (transparent substrate 15) so that the opposing electrode area was 3 mm ² . On the ITO substrate, the following organic layer and electrode layer were vacuum-deposited by resistance heating in a vacuum chamber of 10 ⁻⁴ Pa to form a continuous film.
Hole transport layer 13 (40 nm): α-NPD
Light-emitting layer 12 (30 nm): CBP and metal coordination compounds shown in Table 16 (weight ratio of metal coordination compounds 5% by weight)
Electron transport layer 16 (30 nm): Alq3
Metal electrode layer 1 (15 nm): AlLi alloy (Li content 1.8 wt%)
Metal electrode layer 2 (100 nm): Al

An electric field was applied with the transparent electrode 14 side as an anode and the metal electrode 11 side as a cathode, and a voltage was applied so that the current value was the same in each element, and a change in luminance with time was measured. Since oxygen and water are the causes of device deterioration, the above measurement was performed in a dry nitrogen flow after removal from the vacuum chamber in order to remove the cause. The constant current amount was 70 mA / cm ² . The luminance range of each element obtained at that time was 90 to 280 cd / m ² . The results are shown in Table 16.

  The luminance half-life is clearly greater than that of the device of Comparative Example 1 using a conventional light emitting material, and a highly durable device derived from the stability of the material of the present invention is now possible.

<Example 9>
A color organic EL display was prepared using the TFT circuit shown in FIGS. Using a hard mask in the region corresponding to each color pixel, the organic layer and the metal layer were vacuum-deposited for patterning. The configuration of the organic layer corresponding to each pixel is as follows.
Green pixel: α-NPD (50 nm) / Alq (50 nm)
Blue pixel: α-NPD (50 nm) / BCP (20 nm) / Alq (50 nm)
Red pixel: α-NPD (40 nm) / CBP: Phosphorescent material (30 nm) / BCP (20 nm) / Alq (40 nm)

  Examples of phosphorescent materials include Exemplified Compound Nos. 1 was used at a weight ratio of 8%.

  The number of pixels was 128 × 128 pixels. It was confirmed that desired image information could be displayed, and it was found that good image quality was stably displayed.

It is a figure which shows an example of the light emitting element of this invention. It is the figure which showed typically an example of the structure of the panel provided with the EL element and the drive means. It is a figure which shows an example of a pixel circuit. It is the schematic diagram which showed an example of the cross-section of a TFT substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Metal electrode 12 Light emitting layer 13 Hole transport layer 14 Transparent electrode 15 Transparent substrate 16 Electron transport layer 17 Exciton diffusion prevention layer

Claims (21)

A metal coordination compound having at least one partial structure represented by the following general formula (1):
ML (1)
[Wherein the partial structure ML is represented by the following general formula (2), M is a metal atom of Ir, Pt, Rh, Re, Cu, W or Pd, C is a carbon atom, and A is a carbon atom A cyclic group which may have a substituent bonded to the metal atom M via N is a nitrogen atom, and B is a cyclic group which may have a substituent bonded to the metal atom M through the nitrogen atom. The cyclic group B is bonded to the cyclic group A through a single bond and X.

The following general formula (3) including the cyclic group B in the general formula (2)

Is represented by the following general formula (4).

In the general formula (4), E _{1 to} E ₅ each represent a nitrogen atom or a CH group, and the hydrogen atom of the CH group may be replaced with a substituent. X is a linear or branched alkylene group having 2 to 10 carbon atoms (one or two or more methylene groups in the alkylene group are —O—, —S—, —CO—, —CO -O-, -O-CO-, -CH = CH-, -C≡C- may be substituted, and a hydrogen atom in the alkylene group may be substituted by a fluorine atom). .
The substituents of E _{1 to} E ₅ and cyclic group A are a halogen atom, a cyano group, a nitro group, a di-substituted amino group {the substituents may each independently have a phenyl group or a naphthyl group. (The substituent is a halogen atom, a methyl group or a trifluoromethyl group) or a linear or branched alkyl group having 1 to 8 carbon atoms, and the hydrogen atom in the alkyl group is a fluorine atom. May be substituted. }, A trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear or branched group having 1 to 20 carbon atoms An alkyl group {one or two or more non-adjacent methylene groups in the alkyl group are -O-, -S-, -CO-, -CO-O-, -O-CO-, -CH = CH-, -C≡C- may be substituted, and one or more methylene groups in the alkyl group may have a substituent, a divalent aromatic ring group (the substituent is a halogen atom) , A cyano group, a nitro group, a trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear chain having 1 to 20 carbon atoms Or a branched alkyl group (if one of the alkyl groups Two or more non-adjacent methylene groups are replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—. Or a hydrogen atom in the alkyl group may be substituted with a fluorine atom.)), Or a hydrogen atom in the alkyl group may be substituted with a fluorine atom. Good. }. Further, adjacent substituents may be bonded to form a ring structure. ] It is shown by following General formula (5), The metal coordination compound of Claim 1 characterized by the above-mentioned.
MLm L'n (5)
[Wherein, M is a metal atom of Ir, Pt, Rh or Pd, and L and L ′ represent different bidentate ligands. m is 1 or 2 or 3, and n is 0 or 1 or 2. However, m + n is 2 or 3. The partial structure ML′n is represented by the following general formula (6), (7), (8) or (9).

In general formulas (6), (7), and (9), N and C are nitrogen and a carbon atom. A ′ and A ″ are cyclic groups which may have a substituent bonded to the metal atom M via a carbon atom, and B ′, B ″ and B ′ ″ are each a metal atom via a nitrogen atom. A cyclic group which may have a substituent bonded to M, and the cyclic group B ′ is bonded to the cyclic group A ′ via a single bond and X ′, and the cyclic group A ″ and the cyclic group B ″ Are linked by a covalent bond.
The following general formula (10) including the cyclic group B ′ in the general formula (6)

Is represented by the following general formula (11).

In General Formula (11), E ₁ ′ to E ₅ ′ each represent a nitrogen atom or a CH group, and the hydrogen atom of the CH group may be replaced with a substituent. X ′ represents a linear or branched alkylene group having 2 to 10 carbon atoms (one or two or more non-adjacent methylene groups in the alkylene group are —O—, —S—, —CO—, — CO—O—, —O—CO—, —CH═CH—, —C≡C— may be substituted, and a hydrogen atom in the alkylene group may be substituted with a fluorine atom). is there.
The substituents of the cyclic groups A ′, A ″, B ″, B ′ ″ and E ₁ ′ to E ₅ ′ are halogen atoms, cyano groups, nitro groups, disubstituted amino groups {the substituents are each independently An optionally substituted phenyl group, naphthyl group (the substituent is a halogen atom, a methyl group or a trifluoromethyl group), or a linear or branched alkyl having 1 to 8 carbon atoms; A hydrogen atom in the alkyl group may be substituted with a fluorine atom. }, A trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a linear or branched structure having 1 to 20 carbon atoms An alkyl group in which one or two or more methylene groups in the alkyl group are —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— , -C≡C-, and one or two or more methylene groups in the alkyl group may be substituted with a divalent aromatic ring group (the substituent is a halogen atom) An atom, a cyano group, a nitro group, a trialkylsilyl group (the alkyl groups are each independently a linear or branched alkyl group having 1 to 8 carbon atoms), a straight chain having 1 to 20 carbon atoms, A chain or branched alkyl group (including one of the alkyl groups) Or two or more non-adjacent methylene groups are replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—. And a hydrogen atom in the alkyl group may be substituted with a fluorine atom.)), And a hydrogen atom in the alkyl group may be substituted with a fluorine atom. Also good. }. Further, adjacent substituents may be bonded to form a ring structure.
In the general formula (8), E, G and J are each independently a linear or branched alkyl group having 1 to 20 carbon atoms {one or two or more methylene groups not adjacent to each other in the alkyl group] May be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH—, —C≡C—, and 1 in the alkyl group. One or two or more methylene groups may have a divalent aromatic ring group (the substituent is a halogen atom, a cyano group, a nitro group, a trialkylsilyl group (the alkyl group is independently A straight-chain or branched alkyl group having 1 to 8 carbon atoms.), A straight-chain or branched alkyl group having 1 to 20 carbon atoms (one or two adjacent groups in the alkyl group). One or more methylene groups are —O—, —S—, —CO—, —CO—. -, -O-CO-, -CH = CH-, -C≡C- may be substituted, and a hydrogen atom in the alkyl group may be substituted by a fluorine atom). The adjacent substituents may be bonded to form a ring structure.), And a hydrogen atom in the alkyl group may be substituted with a fluorine atom. } Or a di-substituted amino group {the substituents may each independently have a phenyl group, a naphthyl group (the substituent is a halogen atom, a methyl group or a trifluoromethyl group) or carbon. A linear or branched alkyl group having 1 to 8 atoms, and a hydrogen atom in the alkyl group may be substituted with a fluorine atom. }. J may be a hydrogen atom. ] It is shown by following General formula (12), The metal coordination compound of Claim 1 characterized by the above-mentioned.

[Wherein Cl means a chlorine atom, and M is Ir or Rh. ]   The metal coordination compound according to claim 2, wherein the partial structure ML'n is represented by the general formula (6).   The metal coordination compound according to claim 2, wherein the partial structure ML'n is represented by the general formula (7).   The metal coordination compound according to claim 2, wherein the partial structure ML'n is represented by the general formula (8).   The metal coordination compound according to claim 2, wherein the partial structure ML'n is represented by the general formula (9).   3. The metal coordination compound according to claim 2, wherein n is 0.   The cyclic group A ′ is an aromatic ring group that may have a substituent, such as a phenylene group, a naphthylene group, a thienylene group, a fluorenylene group, a thianaphthylene group, an acenaphthylene group, an anthranylene group, a phenanthrenylene group, a pyrenylene group, Selected from carbazolinylene groups (one or two of the CH groups constituting the aromatic ring group may be replaced by a nitrogen atom), and the cyclic group A ″ may have a substituent Phenyl group, naphthyl group, thienyl group, fluorenyl group, thianaphthyl group, acenaphthyl group, anthranyl group, phenanthrenyl group, pyrenyl group, carbazolyl group (one or two of the CH groups constituting the aromatic ring group are nitrogen The metal coordination compound according to claim 2, wherein the metal coordination compound is selected from the group consisting of:   The metal coordination compound according to claim 8, wherein the cyclic group A 'is a phenylene group which may have a substituent.   Next to the position (1-position) where the phenylene group which may have a substituent is bonded to the cyclic group B ′ by a single bond (6-position), the cyclic group B ′ The metal coordination compound according to claim 9, wherein the metal coordination compound is bonded. The cyclic groups A ′, A ″, B ″, B ′ ″ and E ₁ ′ to E ₅ ′ are each unsubstituted or a halogen atom or a linear or branched alkyl group having 1 to 20 carbon atoms { One or two or more non-adjacent methylene groups in the alkyl group may be replaced by -O-, -S-, -CO-, -CH = CH-, -C≡C-. One or two or more methylene groups in the group may be a divalent aromatic ring group which may have a substituent (the substituent is a halogen atom, a linear or branched group having 1 to 20 carbon atoms) An alkyl group (one or two or more methylene groups not adjacent to each other in the alkyl group may be replaced with -O-, and a hydrogen atom in the alkyl group may be replaced with a fluorine atom); Hydrogen in the alkyl group, which may be replaced by The atom may be substituted with a fluorine atom.} The metal coordination compound according to claim 2, having a substituent selected from the group consisting of:   The cyclic group A is an aromatic ring group which may have a substituent, such as a phenylene group, a naphthylene group, a thienylene group, a fluorenylene group, a thianaphthylene group, an acenaphthylene group, an anthranylene group, a phenanthrenylene group, a pyrenylene group, The metal arrangement according to any one of claims 1 to 14, which is selected from carbazolinylene groups (one or two of the CH groups constituting the aromatic ring group may be replaced by a nitrogen atom). Coordination compound.   The metal coordination compound according to claim 15, wherein the cyclic group A is a phenylene group which may have a substituent.   Next to the position (1-position) where the phenylene group which may have a substituent is bonded to the cyclic group B with a single bond (6-position), The metal coordination compound according to claim 16, wherein: The cyclic groups A and E _{1 to} E ₅ are each unsubstituted, a halogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms {one or two or more not adjacent to the alkyl group The methylene group may be replaced by —O—, —S—, —CO—, —CH═CH—, —C≡C—, and one or more methylene groups in the alkyl group are A divalent aromatic ring group which may have a substituent (the substituent is a halogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms (one or not adjacent to the alkyl group); Two or more methylene groups may be replaced by -O-, and a hydrogen atom in the alkyl group may be replaced by a fluorine atom). The hydrogen atom in the alkyl group is placed on the fluorine atom. It may be. The metal coordination compound according to claim 1, wherein the metal coordination compound has a substituent selected from.   The metal coordination compound according to claim 1, wherein M is iridium.   It is an organic light emitting element provided with the light emission part containing at least 1 type of organic compound between a pair of electrodes provided on the base | substrate, Comprising: The said organic compound is a metal coordination compound in any one of Claims 1-17. An organic light emitting device comprising:   The organic light-emitting device according to claim 18, wherein phosphorescence is emitted by applying a voltage between the electrodes.   The organic light-emitting element according to claim 19, wherein the phosphorescent color is red.   21. An image display device comprising: the organic light-emitting device according to claim 18; and means for supplying an electric signal to the organic light-emitting device.

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