KR20070081406A - Cyclometalated transition metal complex and organic electroluminescence device using the same - Google Patents

Abstract

Cyclometalated transitional compound for organic electro-luminescence device is provided to emit light in red regions through intersystem crossing(ISC) and MLCT(metal-to-ligand charge-transfer) and to be used for an organic film for the EL device by comprising particular assistant ligands. A transitional compound is represented by any one of the formulae(1) and (2), wherein M is transitional metal; ligands comprises bidentate chelating ligand, mono anionic bidentate chelating ligand, and mono anionic bidentate chelating ligand; X is independently C, S, O or N; CY1, CY2, CY3 and CY4 are aromatic or aliphatic ring; and n is 1 or 2. The organic EL device includes a pair of electrodes and an organic film comprising the transitional compound. The organic film further includes at least one selected from higher polymer host, lower polymer host, mixture thereof and non-emitting polymer matrix.

Description

Cyclometalated transition metal complex and organic electroluminescence device using the same}

1A to 1C are cross-sectional views briefly illustrating a structure of an organic light emitting diode according to the present invention.

2 is a graph showing the results of the ¹ H NMR experiment of the compound 7 according to the present invention.

3 is a graph showing the results of UV and PL experiments of compound 7 according to the present invention.

4 is a graph showing the results of UV and PL experiments of compound 9 according to the present invention.

5 is a graph showing the results of UV and PL experiments of compounds 8 and 10 according to the present invention.

6 is a diagram showing the results of X-ray single crystal analysis of Compound 7 according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cyclometalated transition metal compound and an organic electroluminescent device using the same, and more particularly cyclometallization capable of emitting light in a red region from triplet metal-to-ligand charge-transfer A transition metal compound and an organic electroluminescent element employing the same as an organic film forming material.

An organic electroluminescent device (organic EL device) is an active light emitting type using a phenomenon in which light is generated while electrons and holes are combined in an organic film when a current flows through a thin film of fluorescent or phosphorescent organic compound (hereinafter referred to as an organic film). As a display element, it is lightweight, has a simple structure, a simple manufacturing process, and secures a wide viewing angle at high image quality. In addition, high color purity and video can be perfectly realized, and low power consumption and low voltage driving make it suitable for portable electronic devices.

A general organic electroluminescent device has an anode in which an anode is formed on a substrate, and a hole transporting layer, a light emitting layer, an electron transporting layer and a cathode are sequentially formed on the anode. Here, the hole transport layer, the light emitting layer, and the electron transport layer are organic films made of an organic compound. The driving principle of the organic EL device having the structure as described above is as follows. When voltage is applied between the anode and the cathode, holes injected from the anode are moved to the light emitting layer via the hole transport layer. On the other hand, electrons are injected into the light emitting layer from the cathode via the electron transport layer, and carriers are recombined in the light emitting layer to generate excitons. As the excitons are radiated decay, light of a wavelength corresponding to the band gap of the material is emitted.

The light emitting layer forming material of the organic EL device may be classified into a fluorescent material using excitons in a singlet state and a phosphorescent material using a triplet state according to the light emitting mechanism thereof. The fluorescent or phosphorescent material is doped on its own or in a suitable host material to form a light emitting layer, and as a result of electron excitation, singlet excitons and triplet excitons are formed in the host. At this time, the statistical ratio of singlet excitons and triplet excitons is 1: 3.

The organic EL device using a fluorescent material as a light emitting layer forming material has a disadvantage in that the triplet generated in the host is wasted. On the other hand, when a phosphor is used as the light emitting layer forming material, singlet excitons and triplet excitons are used. Both have the advantage of reaching 100% internal quantum efficiency (Baldo, et al., Nature, Vol. 395, 151-154, 1998). Therefore, when the phosphor is used as the light emitting layer forming material, it can have a much higher luminous efficiency than the fluorescent material.

When heavy metals such as Ir, Pt, Rh, and Pd are introduced into organic molecules, triplet and singlet states are induced through spin-orbital coupling caused by heavy atom effects. This results in a forbidden transition, which allows for efficient phosphorescence at room temperature.

Recently, high-efficiency green materials using phosphorescence with internal quantum efficiency up to 100% have been developed.

However, as a high efficiency light emitting material using such phosphorescence, various materials using transition metal compounds including transition metals such as iridium and platinum have been published, but high efficiency full color displays or low power consumption white light emitting applications It is a situation that does not satisfy the luminous efficiency etc. which are the characteristics required for realization.

Particularly, in the case of red, luminous efficiency of about 3 lm / W is required for full colorization, but currently only about 1 lm / W is reached.

Therefore, the technical limitations of the conventional red light emitting materials are overcome, and further improved physical properties and development of the red light emitting materials are still required.

The first technical problem to be achieved by the present invention is to provide a cyclometalated transition metal compound capable of efficiently emitting red wavelength light from triplet MLCT.

The second technical problem to be achieved by the present invention is to provide an organic EL device capable of efficiently emitting red light.

The present invention to achieve the first technical problem,

It provides a cyclometalated transition metal compound represented by the following formula (1) or formula (2):

<Formula 1> <Formula 2>

In Chemical Formula 1 or 2,

M is a transition metal,

는 제 1 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is the first mono anionic bidentate chelating ligand,

는 제 2 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is a second mono anionic bidentate chelating ligand,

는 제 3 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is a third mono anionic bidentate chelating ligand,

Each X is independently C, S, O or N,

CY1, CY2, CY3 and CY4 are aromatic or aliphatic rings,

n is 1 or 2.

The present invention also to achieve the first technical problem,

It provides a cyclometalated transition metal compound represented by the formula (3):

<Formula 3>

In Chemical Formula 3,

M is a transition metal,

는 제 1 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is the first mono anionic bidentate chelating ligand,

는 디 음이온성 테트라덴테이트 킬레이팅 리간드이고,

Is a dianionic tetradentate chelating ligand,

X is C, S, O or N,

CY1, CY2 and CY5 are aromatic or aliphatic rings,

n is 1 or 2.

The present invention also to achieve the first technical problem,

According to one embodiment of the invention, it is preferred that the first monoanionic bidentate ligand in the cyclometallated transition metal compounds is any one selected from the group consisting of ligands represented by the formula:

In which Z is S, O or NR ₈ ,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino Or an arylene group, and adjacent R's may be fused to each other to form an aliphatic or aromatic ring having 5 to 7 angles.

According to another embodiment of the present invention, it is preferable that the second monoanionic bidentate ligand in the cyclometalated transition metal compound is any one selected from the group consisting of ligands represented by the following formulas:

In the above formulas,

Z is C, N, O, S, or P, q is an integer from 0 to 5,

R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed.

According to another embodiment of the present invention, it is preferable that the second monoanionic bidentate ligand in the cyclometalated transition metal compound is any one selected from the group consisting of ligands represented by the following formulas:

According to another embodiment of the present invention, in the cyclometalated transition metal compound, it is preferable that the third monoanionic bidentate ligand is any one selected from the group consisting of ligands represented by the following formulas.

In the above formulas,

Z is C, N, O, S, or P, q is an integer from 0 to 5,

R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed.

According to another embodiment of the present invention, the dianionic tetradentate ligand in the cyclometalated transition metal compound is preferably any one selected from the group consisting of ligands represented by the following formula:

In the above formulas,

Z is C, N, O, S, or P, q is an integer from 0 to 5,

R ₁ and R ₂ are each independently hydrogen, halogen, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene group, and adjacent Rs are fused to each other It may form an aliphatic or aromatic ring.

According to another embodiment of the present invention, the dianionic tetradentate ligand in the cyclometalated transition metal compound is preferably any one selected from the group consisting of ligands represented by the following formula:

According to another embodiment of the present invention, in the cyclometalated transition metal compound, M is preferably Ru, Rh, Os, Ir, Pt or Au.

According to another embodiment of the present invention, in the cyclometalated transition metal compound, M is preferably Ir.

According to another embodiment of the present invention, in the cyclometalated transition metal compound, the transition metal compound of Formula 1 or Formula 2 is preferably any one of compounds represented by the following formula:

<Formula 4> <Formula 5>

<Formula 6>

<Formula 7> <Formula 8>

According to another embodiment of the present invention, in the cyclometalated transition metal compound, the transition metal compound of Formula 3 is preferably any one of compounds represented by the following formula:

<Formula 9>

<Formula 10>

The present invention to achieve the second technical problem,

In an organic electroluminescent device comprising an organic film between a pair of electrodes,

It provides an organic electroluminescent device characterized in that the organic film comprises a cyclometalated transition metal compound according to the above.

According to an embodiment of the present invention, the organic layer in the organic electroluminescent device further comprises one or more selected from the group consisting of at least one polymer host, a mixture of a polymer host and a low molecular host, a low molecular host, and a non-luminescent polymer matrix It is desirable to.

According to another embodiment of the present invention, it is preferable that the organic layer further includes a green light emitting material or a blue light emitting material in the organic electroluminescent device.

The cyclomethylated transition metal compound according to the present invention can efficiently emit phosphorescence in the red region through metal to ligand charge transfer (MLCT) after ISC (Intersystem Crossing) to triplet by including a new auxiliary ligand. The organic EL device manufactured using the transition metal compound may provide improved light emission characteristics such as high light emission efficiency and external quantum efficiency, unlike conventional light emitting devices having low light emission efficiency in the red region.

Hereinafter, the present invention will be described in more detail.

The present invention provides a cyclometalated transition metal compound represented by Formula 1 below:

<Formula 1> <Formula 2>

In Chemical Formula 1 or 2,

M is a transition metal,

는 제 1 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is the first mono anionic bidentate chelating ligand,

는 제 2 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is a second mono anionic bidentate chelating ligand,

는 제 3 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is a third mono anionic bidentate chelating ligand,

X is C, S, O or N,

CY1, CY2, CY3 and CY4 are aromatic or aliphatic rings,

n is 1 or 2.

The compounds of Formula 1 and Formula 2 may be in an isomeric relationship with each other depending on the type of ligand.

The present invention also provides a binuclear cyclometalated transition metal compound represented by Formula 3 below:

<Formula 3>

In Chemical Formula 3,

M is a transition metal,

는 제 1 모노 음이온성 바이덴테이트 킬레이팅 리간드이고,

Is the first mono anionic bidentate chelating ligand,

는 디 음이온성 테트라덴테이트 킬레이팅 리간드이고,

Is a dianionic tetradentate chelating ligand,

X is C, S, O or N,

CY1, CY2 and CY5 are aromatic or aliphatic rings,

n is 1 or 2.

The cyclometallation transition metal compound of Chemical Formulas 1 to 3 may include a first monoanionic bidentate chelating ligand as a main ligand and a second monoanionic bidentate chelating ligand as a secondary ligand, a third monoanionic bi Its structural feature is the transition metal compound coordinated with a dentate chelating ligand, or a dianionic tetradentate chelating ligand, with the coordination of a novel ligand auxiliary structure. The coordination of the auxiliary ligand of the new structure greatly improves the luminous efficiency of the device when used in the organic electroluminescent device as compared to the conventional red fluorescent material as well as the red phosphorescent material.

In Formulas 1 to 3, CY1, CY2, CY3, CY4 and CY5 are aromatic or aliphatic rings, which may be aliphatic or aromatic rings including one or more heteroatoms, and may include one or more substituents.

The substituents are halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent substituents are fused to each other to add 5-7 aliphatic or aromatic rings. Can be formed.

In the substituent, preferably, the alkyl group has 1 to 30 carbon atoms, the aryl group has 5 to 30 carbon atoms, the alkoxy group has 1 to 30 carbon atoms, and the aryloxy group has 5 to 30 carbon atoms, The arylene group has 2 to 30 carbon atoms.

In the cyclometallated transition metal compound represented by Formula 1 and Formula 2, the first monoanionic bidentate ligand is preferably any one selected from the group consisting of ligands represented by the following formula:

In which Z is S, O or NR ₈ ,

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino Or an arylene group, and adjacent R's may be fused to each other to form an aliphatic or aromatic ring having 5 to 7 angles. And the adjacent R's include R ₁ and R ₂ .

In the R ₁ to R ₈ , preferably, the alkyl group has 1 to 30 carbon atoms, the aryl group has 5 to 30 carbon atoms, the alkoxy group has 1 to 30 carbon atoms, and the aryloxy group has 5 to 30 carbon atoms 30 and the arylene group has 2 to 30 carbon atoms.

In the cyclometalated transition metal compound represented by Formula 1, the second monoanionic bidentate ligand is preferably any one selected from the group consisting of ligands represented by the following formulas:

In the above formulas,

Z is C, N, O, S, or P, q is an integer from 0 to 5,

Z may be present in a plurality of chemical formulas but may be C, N, O, S, or P independently of each other depending on the position

R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring may be formed, wherein the adjacent Rs comprise R ₁ and R ₂ .

In R ₁ and R ₂ , preferably, the alkyl group has 1 to 30 carbon atoms, the aryl group has 5 to 30 carbon atoms, the alkoxy group has 1 to 30 carbon atoms, and the aryloxy group has 5 to 30 carbon atoms 30 and the arylene group has 2 to 30 carbon atoms.

More specifically, the cyclometallated transition metal compound, characterized in that the second monoanionic bidentate ligand is any one selected from the group consisting of ligands represented by the following formula:

In the cyclometalated transition metal compound represented by Formula 2, the third monoanionic bidentate ligand is preferably any one selected from the group consisting of ligands represented by the following formulas.

In the above formulas,

Z is C, N, O, S, or P, q is an integer from 0 to 5,

R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed.

In R ₁ and R ₂ , preferably, the alkyl group has 1 to 30 carbon atoms, the aryl group has 5 to 30 carbon atoms, the alkoxy group has 1 to 30 carbon atoms, and the aryloxy group has 5 to 30 carbon atoms 30 and the arylene group has 2 to 30 carbon atoms.

In the cyclometalated transition metal compound represented by Formula 3, the dianionic tetradentate ligand is preferably any one selected from the group consisting of ligands represented by the following formula:

In the above formulas,

Z is C, N, O, S, or P, q is an integer of 0 to 5, wherein Z is a plurality in the formulas but independently from each other according to the position C, N, O, S, Or P

R ₁ and R ₂ are each independently hydrogen, halogen, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene group, and adjacent Rs are fused to each other And may form an aliphatic or aromatic ring, wherein adjacent Rs comprise R ₁ and R ₂ .

In R ₁ and R ₂ , preferably, the alkyl group has 1 to 30 carbon atoms, the aryl group has 5 to 30 carbon atoms, the alkoxy group has 1 to 30 carbon atoms, and the aryloxy group has 5 to 30 carbon atoms 30 and the arylene group has 2 to 30 carbon atoms.

More specifically, the dianionic tetradentate ligand in the cyclometalated transition metal compound is preferably any one selected from the group consisting of ligands represented by the following formula:

In the cyclometallated transition metal compound of Chemical Formulas 1 to 3, M is preferably Ru, Rh, Os, Ir, Pt, or Au.

More specifically, it is particularly preferable that M is Ir in the cyclometallated transition metal compound.

In the cyclometallated transition metal compound, the transition metal compound of Formula 1 or Formula 2 is more preferably any one of the compounds represented by the following Formulas 4 to 7 :

<Formula 4> <Formula 5>

<Formula 6>

<Formula 7> <Formula 8>

The compound of Formula 4 and the compound of Formula 7 are isomeric to each other, and the compound of Formula 5 and the compound of Formula 8 are also isomeric to each other. That is, the compounds of Formulas 4, 5, 7 and 8 can be expressed as follows.

Further, in the cyclometalated transition metal compound, the transition metal compound of Formula 3 is more preferably any one of the compounds represented by the following Formulas 9 to 10:

<Formula 9>

<Formula 10>

The cyclometalated transition metal compound according to the present invention has a luminescence property in the wavelength band between 500nm and 670nm.

Cyclometallated transition metal compounds according to the invention are reported by the Watts group using the starting material [Ir (CY1) (CY2) Cl] ₂ derivative, for example when M is Ir (FOGarces) , RJ Watts, Inorg. Chem. 1988, (35), 2450).

Hereinafter, a synthetic route of a transition metal compound having a bipyridinediol ligand, which is an embodiment of the compound of Formula 1, will be described.

Referring to the following scheme, the sodium salt of [Ir (CY1) (CY2) Cl] ₂ derivative and 2,2-bipyridine-3,3-diol was added to a mixed solvent of chloroform and methanol (3: 1), By stirring for 18 hours at a temperature of 30 ~ 50C it is possible to synthesize a cyclometalated transition metal compound of the present invention.

<Scheme 1>

The present invention provides an organic electroluminescent device comprising an organic film between a pair of electrodes (first electrode and second electrode), wherein the organic film comprises a cyclometalated transition metal compound according to the above. Provided is a light emitting device.

At this time, the transition metal compound represented by Chemical Formulas 1 to 3 is very useful as a phosphorescent dopant material which is a light emitting layer forming material, and exhibits excellent light emission characteristics in the red wavelength region.

When the transition metal compound is used as a phosphorescent dopant in the organic electroluminescent device, the organic layer may include at least one selected from the group consisting of at least one polymer host, a mixture of a polymer host and a low molecular host, a low molecular host, and a non-luminescent polymer matrix. It is preferable to further include.

Herein, the polymer host, the low molecular host, and the non-luminescent polymer matrix may be used as long as they are commonly used in forming an emission layer for an organic EL device. Examples of the polymer host include PVK (polyvinylcarbazole) and polyfluorene. Examples of low molecular weight hosts include CBP (4,4'-N, N'-dicarbazole-biphenyl), 4,4'-bis [9- (3,6-biphenylcarbazolyl)]-1, 1'-biphenyl, 9,10-bis [(2 ', 7'-t-butyl) -9', 9 ''-spirobifluorenylanthracene, tetrafluorene, and the like. Polymethyl methacrylate, polystyrene, and the like, but is not limited thereto.

The content of the transition metal compound according to the present invention is preferably 1 to 30 parts by weight based on 100 parts by weight of the total weight of the light emitting layer forming material. In order to introduce such a transition metal compound into the light emitting layer, a vacuum deposition method, a sputtering method, a printing method, a coating method, an inkjet method, a method using an electron beam, or the like can be used.

In the organic electroluminescent device, the organic layer may further include a green light emitting material or a blue light emitting material. In this case, white light may be emitted.

It is preferable that the thickness of an organic film is 10-1000 nm here. Herein, the organic film refers to a film made of an organic compound formed between a pair of electrodes in an organic electroluminescent device, such as an electron transport layer and a hole transport layer, in addition to the light emitting layer.

Fabrication of the organic electroluminescent device of the present invention does not require a special device or method, it can be produced according to the manufacturing method of the organic electroluminescent device using a conventional light emitting material.

The structure of the organic electroluminescent device according to the present invention is very diverse. Between the pair of electrodes may further include one or more layers selected from the group consisting of a buffer layer, a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer and an electron injection layer.

More specifically, an embodiment of the organic light emitting device according to the present invention refers to Figures 1a, 1b and 1c. The organic light emitting device of FIG. 1A has a structure consisting of a first electrode / hole injection layer / light emitting layer / electron transport layer / electron injection layer / second electrode, and the organic light emitting device of FIG. 1B includes a first electrode / hole injection layer / hole transport layer. / Light emitting layer / electron transport layer / electron injection layer / second electrode. In addition, the organic light emitting device of FIG. 1C has a structure of a first electrode / hole injection layer / light emitting layer / hole blocking layer / electron injection layer / second electrode. In this case, the light emitting layer may include a transition metal compound according to the present invention. The light emitting layer of the organic light emitting device according to the present invention may include a phosphorescent or fluorescent dopant including green, blue or white. Hereinafter, a method of manufacturing an organic light emitting diode according to the present invention will be described with reference to the organic light emitting diode illustrated in FIG. 1C.

First, a first electrode material having a high work function on the substrate is formed by a deposition method or a sputtering method to form a first electrode. The first electrode may be an anode. Herein, a substrate used in a conventional organic light emitting device is used, and a glass substrate or a transparent plastic substrate having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproofness is preferable. Indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2), zinc oxide (ZnO), and the like, which are transparent and have excellent conductivity, are used as the material for the first electrode.

Next, a hole injection layer HIL may be formed on the first electrode by using various methods such as vacuum deposition, spin coating, casting, and LB.

In the case of forming the hole injection layer by vacuum deposition, the deposition conditions vary depending on the compound used as the material of the hole injection layer, the structure and thermal properties of the hole injection layer, and the like. It is preferable that a vacuum degree of 10 ^-8 to 10 ^-3 torr, a deposition rate of 0.01 to 100 mW / sec, and a film thickness are usually appropriately selected in the range of 10 mV to 5 m.

In the case of forming the hole injection layer by spin coating, the coating conditions vary depending on the compound used as the material of the hole injection layer, the structure and the thermal properties of the desired hole injection layer, but the coating speed is about 2000 rpm to 5000 rpm. The heat treatment temperature for solvent removal after coating is preferably selected in the temperature range of about 80 ° C to 200 ° C.

The hole injection layer material is not particularly limited, and for example, a phthalocyanine compound such as copper phthalocyanine disclosed in U.S. Patent No. 4,356,429 or a starburst amine derivative described in Advanced Material, 6, p.677 (1994). Residual TCTA, m-MTDATA, m-MTDAPB, Pani / DBSA (Polyaniline / Dodecylbenzenesulfonic acid: polyaniline / dodecylbenzenesulfonic acid) or PEDOT / PSS (Poly (3,4-ethylenedioxythiophene) / Poly () 4-styrenesulfonate): poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate)), Pani / CSA (Polyaniline / Camphor sulfonic acid: polyaniline / camphorsulfonic acid) or PANI / PSS (Polyaniline) / Poly (4-styrenesulfonate): polyaniline) / poly (4-styrenesulfonate)) and the like can be used.

    Pani / DBSA PEDOT / PSS

The hole injection layer may have a thickness of about 100 kPa to 10000 kPa, preferably 100 kPa to 1000 kPa. This is because when the thickness of the hole injection layer is less than 100 kV, the hole injection characteristic may be lowered, and when the thickness of the hole injection layer exceeds 10000 kV, the driving voltage may increase.

Next, the light emitting layer EML may be formed on the hole injection layer by using a vacuum deposition method, a spin coating method, a cast method, an LB method, or the like. When the light emitting layer is formed by the vacuum deposition method or the spin coating method, the deposition conditions vary depending on the compound used, but are generally selected from the ranges of conditions substantially the same as those of forming the hole injection layer.

The light emitting layer may be prepared using an arylene derivative including a polar functional group of Formula 1 according to the present invention as described above. In this case, an organic semiconductor may be used together with the soluble compound. For example, pentacene, polythiophene, tetrathiafulvalene, or the like can be used.

On the other hand, the arylene-based derivative of Formula 1 may be used with a suitable known host material. In the case of the host material, for example, Alq ₃ or CBP (4,4'-N, N'-dicarbazole-biphenyl), PVK (poly (n-vinylcarbazole)) or the like can be used.

       PVK

Meanwhile, as the light emitting layer forming material, various known dopants may be used in addition to the aminostyryl compound according to the present invention. For example, as the fluorescent dopant, IDE102, IDE105, and C545T, available from Hayamibara, may be used. The phosphorescent dopant may be a red phosphorescent dopant PtOEP, an UD RD 61, or a green phosphorescent dopant Ir. (PPy) ₃ (PPy = 2-phenylpyridine), F2Irpic which is a blue phosphorescent dopant, red phosphorescent dopant RD 61 by UDC, etc. can be used.

Doping concentration is not particularly limited, but the content of the dopant is generally 0.01 to 15 parts by weight based on 100 parts by weight of the host.

The thickness of the light emitting layer may be about 100 kPa to 1000 kPa, preferably 200 kPa to 600 kPa. This is because, when the thickness of the light emitting layer is less than 100 kW, the light emission characteristics may be reduced, and when the thickness of the light emitting layer exceeds 1000 kW, the driving voltage may increase.

In the case of using the phosphorescent dopant in the light emitting layer, in order to prevent the triplet excitons or holes from diffusing into the electron injection layer, holes such as vacuum deposition, spin coating, cast, LB, etc. are formed on the light emitting layer. The blocking layer HBL may be formed. In the case of forming the hole blocking layer by vacuum deposition or spin coating, the conditions vary depending on the compound used, but are generally selected from the ranges of conditions almost the same as that of forming the hole injection layer. Known hole blocking materials which can be used, for example, oxadiazole derivatives or triazole derivatives, phenanthroline derivatives, or hole blocking materials described in JP 11-329734 (A1), BCP (2,9-dimethyl-4 , 7-diphenyl-1,10-phenanthroline).

The hole blocking layer may have a thickness of about 50 kPa to 1000 kPa, preferably 100 kPa to 300 kPa. This is because when the thickness of the hole blocking layer is less than 50 kV, the hole blocking property may be deteriorated. When the thickness of the hole blocking layer is more than 1000 kV, the driving voltage may increase.

In addition, an electron injection layer (EIL), which is a material having a function of facilitating injection of electrons from the cathode, may be stacked on the hole blocking layer, which does not particularly limit the material.

As the electron injection layer, any material known as an electron injection layer forming material such as LiF, NaCl, CsF, Li ₂ O, BaO or the like can be used. The deposition conditions of the electron injection layer vary depending on the compound used, but are generally selected from the range of conditions almost the same as the formation of the hole injection layer.

The electron injection layer may have a thickness of about 1 kPa to 100 kPa, preferably 5 kPa to 50 kPa. This is because, when the thickness of the electron injection layer is less than 1 kW, the electron injection characteristic may be deteriorated, and when the thickness of the electron injection layer exceeds 100 kW, the driving voltage may increase.

Finally, the second electrode may be formed on the electron injection layer by using a vacuum deposition method or a sputtering method. The second electrode may be used as a cathode. As the metal for forming the second electrode, a metal, an alloy, an electrically conductive compound having a low work function, and a mixture thereof may be used. Specific examples include lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and the like. Can be mentioned. In addition, a transmissive cathode using ITO and IZO may be used to obtain the front light emitting device.

The organic light emitting device of the present invention is an organic light emitting device having a first electrode, a hole injection layer (HIL), a light emitting layer (EML), a hole blocking layer (HBL), an electron injection layer (EIL), a second electrode structure shown in FIG. In addition, of course, it includes an organic light emitting device having a variety of structures. In addition, the layers may be omitted if necessary.

For example, a buffer layer, a hole transport layer and an electron transport layer may be added.

As a material of the buffer layer, a material commonly used may be used, and copper phthalocyanine, polythiophene, polyaniline, polyacetylene, polypyrrole, polyphenylenevinylene, or derivatives thereof may be used, but is not limited thereto. Do not.

The hole transport layer (HTL) may be formed on the hole injection layer using various methods such as vacuum deposition, spin coating, cast, LB, and the like. When the hole transport layer is formed by the vacuum deposition method or the spinning method, the deposition conditions and the coating conditions vary depending on the compound used, but are generally selected from a range of conditions almost the same as that of the formation of the hole injection layer.

The hole transport layer material is not particularly limited and may be selected from any of known ones used in the hole transport layer. For example, carbazole derivatives such as N-phenylcarbazole and polyvinylcarbazole, N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl]- Conventional amine derivatives having aromatic condensed rings such as 4,4'-diamine (TPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD), and the like Used.

The hole transport layer may have a thickness of about 50 kPa to 1000 kPa, preferably 100 kPa to 600 kPa. This is because when the thickness of the hole transport layer is less than 50 kV, hole transport characteristics may be degraded, and when the thickness of the hole transport layer exceeds 1000 kW, the driving voltage may increase.

On the other hand, the electron transport layer (ETL) is formed using a variety of methods, such as vacuum deposition, spin coating, casting. When the electron transport layer is formed by the vacuum deposition method or the spin coating method, the conditions vary depending on the compound used, but are generally selected from the ranges of conditions almost the same as that of the formation of the hole injection layer. The electron transport layer material functions to stably transport electrons injected from an electron injection electrode (Cathode), polyoxadiazole, quinoline derivatives, especially tris (8-quinolinorate) aluminum (Alq ₃ ), It is also possible to use known materials such as TAZ.

TAZ

The electron transport layer may have a thickness of about 100 kPa to 1000 kPa, preferably 200 kPa to 500 kPa. This is because when the thickness of the electron transport layer is less than 100 kV, the electron transport characteristic may be degraded, and when the thickness of the electron transport layer exceeds 1000 kW, the driving voltage may increase.

The cyclometalated transition metal compound according to the present invention can emit light in the 500 to 670 nm region. The light emitting diode using the organometallic compound can be used for light source lighting for full color display, backlight, outdoor billboard, optical communication, interior decoration, and the like.

Synthesis method of the cyclometalated transition metal compound of Formula 1 to Formula 3 is a conventional organic synthesis method. All synthesized compounds were confirmed their structure by 1H NMR and Mass spectrometer.

Hereinafter, compounds 4 to 11 represented by the formulas 4 to 11 according to the present invention (hereinafter referred to as "compound 4" to "compound 11", respectively), the formula of each compound refers to the formula having the same number as each compound Synthesis examples and examples of the) are specifically illustrated, but the present invention is not limited to the following synthesis examples and examples.

Synthesis Example

Synthesis Example 1 Synthesis of Piq Dimer

<Scheme 2>

Piq dimer ([Ir (Piq) ₂ Cl] ₂ ), a red powder, was synthesized using _2- phenylisoquinoline ligand and IrCl ₃ nH ₂ O. At this time, the synthesis method is J. Am. Che. Soc., 1984, 106, 6647-6653.

Synthesis Example 2 Synthesis of 2- [3- (3,5-dimethoxyphenyl) -1-phenyl] isoquinoline (DMPPiq) Dimer

<Scheme 3>

2- [3- (3,5-dimethoxyphenyl) -1-phenyl] -isoquinoline ligand synthesized through general Suzuki Coupling and IrCl ₃ ㆍ nH ₂ O [3- (3,5-dimethoxyphenyl) -1-phenyl] -isoquinoline dimer [Ir (DMPPiq) ₂ Cl] ₂ was synthesized. At this time, the synthesis method is J. Am. Che. Soc., 1984, 106, 6647-6653.

 EXAMPLE

Example 1 Synthesis of Compound 7 and Compound 9 Represented by <Formula 7> and <Formula 9>

<Formula 7>

<Formula 9>

635 mg (0.5 mmol) of [(Piq) ₂ IrCl] ₂ and 2,2-bipyridine-3,3 prepared in Synthesis Example 1 under a nitrogen atmosphere in a 100 ml two-necked flask equipped with a thermometer, a mechanical stirrer and a reflux condenser. 250 mg (1.2 mmol) of sodium salt of 2,2-bipyridine-3,3-diol treated with diol in a methylene chloride / methanol solvent were dissolved in a chloroform solution and reacted at 50 ° C. for 18 hours. After the reaction was completed, all the solvents were removed by vacuum after cooling to room temperature. The remaining solid was purified by chloroform, and then purified and separated by column chromatography. As a developing solution (Eluent), a mixed solution of chloroform and methanol (10: 1) was used. The final product thus obtained was Compound 7 and Compound 9, red and orange, respectively, with yields of 30 and 10%, respectively. Compound 7 and Compound 9 were identified by ¹ H NMR, respectively. FIG. 2 is a ¹ H NMR chart of Compound 7 and FIG. 6 is an X-ray crystal structure analysis result of Compound 7. FIG.

¹ H-NMR of compound 7 (CDCl ₃ , ppm): 8.96 [m, 2H], 8.28 [d, 2H], 7.91 [m, 2H], 7.76 [m, 4H], 7.60 [d, 2H], 7.33 [d, 2H], 7.07 [m, 4H], 6.83 [m, 4H], 6.29 [dd, 2H]

Example 2 Synthesis of Compound 8 and Compound 10 Represented by <Formula 8> and <Formula 10>

<Formula 8>

<Formula 10>

836 mg (0.5 mmol) and 2,2-bipyridine-3 ([Ir (DMPPiq) ₂ Cl] ₂ ) prepared in Synthesis Example 2 under a nitrogen atmosphere in a 100 ml two-necked flask equipped with a thermometer, a mechanical stirrer and a reflux condenser. 250 mg (1.2 mmol) of sodium salt of 2,2-bipyridine-3,3-diol treated with NaOH in a methylene chloride / methanol solvent were dissolved in a chloroform solution and reacted at 50 ° C. for 18 hours. . After the reaction was completed, all the solvents were removed by vacuum after cooling to room temperature. The remaining solid was purified by chloroform, and then purified and separated by column chromatography. As a developing solution (Eluent), a mixed solution of chloroform and methanol (10: 1) was used. The final product thus obtained was Compound 8 and Compound 10, red and orange, respectively, with yields of 30 and 10%, respectively.

¹ H-NMR (CDCl ₃ , ppm) of Compound 8: 9.11 [d, 1 H], 9.05 [d, 1 H], 8.93 [d, 1 H], 8.56 [m, 2 H], 8.30 [d, 1 H], 7.89 [m, 1H], 7.76-7.74 [m, 6H], 7.39 [d, 1H], 7.23 [d, 1H], 7.01 [dd, 1H], 6.87 [m, 2H], 6.77 [d, 2H], 6.61 [d, 2H], 6.55 [dd, 1H], 6.43 [t, 1H], 6.35 [t, 1H], 6.20 [dd, 1H], 6.12 [d, 1H], 5.61 [m, 1H]

Example 3 Synthesis of Compound 6 Represented by Chemical Formula 6 [Ir (Piq) 2 (hbq)]

<Formula 6>

In a 100 ml two-necked flask equipped with a thermometer, a mechanical stirrer and a reflux condenser, 635 mg (0.5 mmol) of [(Piq) ₂ IrCl] ₂ and 10-hydoxybenzo [h] quinoline (234 mmol) prepared in Synthesis Example 1 under nitrogen atmosphere ), 345 mg (2.5 mmol) of potassium carbonate (K 2 CO 3) was dissolved in a solution of chloroform and methanol (3: 1) and reacted at 50 ° C. for 18 hours. After the reaction was completed, all the solvents were removed by vacuum after cooling to room temperature. The remaining solid was purified using column chromatography by filtration of the melting part using chloroform. As a developing solution (Eluent), a mixed solution of chloroform and methanol (10: 1) was used. The final product thus obtained was red as compound 6, with a yield of 66% each.

Comparative Example 1: Synthesis of Compound 11 (Ir (Piq) ₃ ) of Formula <11>

<Formula 11>

In a 100 ml two-necked flask equipped with a thermometer, a mechanical stirrer and a reflux condenser, 245 mg (0.5 mmol) of Ir (acac) ₃ and 615 mg (3.0 mmol) of 2-phenylisoquinoline were dissolved in a glycerol solution under a nitrogen atmosphere. The reaction was carried out for 26 hours at ℃. After the reaction was cooled to room temperature and water was added to form a precipitate. After filtering this, the remaining solid was washed with cold methanol and diethyl ether, and then the soluble portion using chloroform was purified by column chromatography. As a developing solution (Eluent), a mixed solution of chloroform and methanol (10: 1) was used. The final product thus obtained was red as compound 11, with a yield of 43%.

Evaluation Example 1 Evaluation of Luminescent Properties of Compounds

The luminescence properties were evaluated by evaluating the absorption spectrum and PL (photoluminescence) spectrum of compound 7. First, compound 7 was diluted in chloroform or dichloromethane (CHCl ₃ or CH ₂ Cl ₂ ) at a concentration of 0.2 mM, and absorption spectra were measured using a Shimadzu UV-350 Spectrometer. Meanwhile, Compound 7 was diluted in chloroform or dichloromethane (CHCl ₃ or CH ₂ Cl ₂ ) at a concentration of 10 mM, and PL (Photoluminecscence) using an ISC PC1 Spectrofluorometer equipped with a Xenon lamp was used. The spectrum was measured. The results are shown in Table 1 and FIG. 3. Compound 6 and compounds 8 to 11 were also measured in the same manner.

The results are shown in Table 1, Figure 3 (Compound 7), Figure 4 (Compound 9) and Figure 5 (Compound 8 and 10).

Compound no Absorption wavelength for MLCT (nm) Maximum PL Wavelength (nm) 7 474 626 8 490 626 9 396 598 10 404 603 6 400 618 11 - 624

Evaluation Example 2 Evaluation of Device Characteristics of Samples

Using compound 7 as a dopant for the light emitting layer, an organic light emitting device was manufactured having the following structure: ITO / PEDOT (50 nm) / CBP + PVK + Compound 7 (60 nm) / BAlq 3 (30 nm) / LiF (0.8 nm) / Al (150 nm).

Anode cuts Corning's 15Ω / cm ² (1200Å) ITO glass substrate into 50mm x 50mm x 0.7mm size, ultrasonically cleans for 5 minutes in isopropyl alcohol and pure water, and UV ozone cleansing for 30 minutes. Was used. Bayer PEDOT-PSS (AI4083) was coated on the substrate and heat-treated at 120 ° C. for 5 hours to form a hole injection layer of 50 nm. On top of the hole injection layer, 70 wt% CBP, 24 wt% PVK, and 6 wt% compound 7 were spin-coated, followed by heat treatment at 110 ° C. for 2 hours to form a light emitting layer having a thickness of 60 nm. Thereafter, a BAlq3 compound was vacuum deposited to a thickness of 30 nm on the emission layer to form a hole blocking layer. LiF 0.8 nm (electron injection layer) and Al 150 nm (cathode) were sequentially vacuum deposited on the hole blocking layer to manufacture an organic light emitting device as illustrated in FIG. 1C. This was called Sample 7.

The organic light emitting device was manufactured by the same method as described above for the compound 6 and the compound 8 to 11. These were called Sample 6 and Samples 8-11, respectively.

For samples 6 to 11, driving voltage, brightness, and efficiency were respectively evaluated using a PR650 (Spectroscan) Source Measurement Unit.

Sample number Driving voltage (V) Maximum Current Efficiency (Cd / A) Maximum External Quantum Efficiency (%) Color coordinates (10mA / cm ² ) 7 5 7.5 (at 19.5V) 10.4 (0.68, 0.32) 8 7 5.8 (at 21.5V) 9.8 (0.64,0.36) 9 6 4.1 (at 16V) 8.5 (0.63,0.38) 10 10 3.2 (at 21.5V) 6.5 (0.67, 0.33) 6 7 6.2 (at 20.5V) 9.2 (0.66, 0.32) 11 5 4.6 (at 16V) 9.3 (0.67, 0.33)

As shown in Table 2 above, in the case of Samples 6 to 11 according to the present invention, the maximum current efficiency and the maximum external quantum efficiency are greatly improved compared to Sample 11 of Comparative Example 1, which shows that device characteristics are excellent. .

The cyclomethylated transition metal compound according to the present invention can efficiently emit phosphorescence in the red region through metal to ligand charge transfer (MLCT) after ISC (Intersystem Crossing) to triplet by including a new auxiliary ligand. The organic EL device manufactured using the transition metal compound may provide improved light emission characteristics such as high light emission efficiency and external quantum efficiency.

Claims (15)

A cyclometalated transition metal compound represented by the following formula (1) or (2): <Formula 1> <Formula 2>

In Chemical Formula 1 or 2, M is a transition metal,

Is the first mono anionic bidentate chelating ligand,

Is a second mono anionic bidentate chelating ligand,

Is a third mono anionic bidentate chelating ligand, Each X is independently C, S, O or N, CY1, CY2, CY3 and CY4 are aromatic or aliphatic rings, n is 1 or 2. A cyclometalated transition metal compound represented by the following formula (3): <Formula 3> In Chemical Formula 3, M is a transition metal,

Is the first mono anionic bidentate chelating ligand,

Is a dianionic tetradentate chelating ligand, Each X is independently C, S, O or N, CY1, CY2 and CY5 are aromatic or aliphatic rings, n is 1 or 2. The cyclometalated transition metal compound according to claim 1 or 2, wherein the first monoanionic bidentate ligand is any one selected from the group consisting of ligands represented by the following formulas:

In which Z is S, O or NR ₈ , R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino Or an arylene group, and adjacent R's may be fused to each other to form an aliphatic or aromatic ring having 5 to 7 angles. The cyclometalated transition metal compound according to claim 1, wherein the second monoanionic bidentate ligand is any one selected from the group consisting of ligands represented by the following formulas:

In the above formulas, Z are independently of each other C, N, O, S, or P, q is an integer from 0 to 5, R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed. The cyclometalated transition metal compound according to claim 1, wherein the second monoanionic bidentate ligand is any one selected from the group consisting of ligands represented by the following formulas:

In the above formulas, Y is O, S or NR ₁ , wherein R ₁ , R ₃ , and R ₄ , are independently of each other hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or aryl It's Rengi. The cyclometalated transition metal compound according to claim 1, wherein the third parent is any one selected from the group consisting of ligands represented by the following formula:

In the above formulas, Z is C, N, O, S, or P, q is an integer from 0 to 5, R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed. The cyclometalated transition metal compound according to claim 2, wherein the dianionic tetradentate ligand is any one selected from the group consisting of ligands represented by the following formulas:

In the above formulas, Z is C, N, O, S, or P, q is an integer from 0 to 5, R ₁ and R ₂ are each independently hydrogen, halogen, OH, CF ₃ , CN, silyl, alkyl, aryl, alkoxy, aryloxy, amino or arylene groups, and adjacent Rs are fused to each other to form 5 to 7 Each aliphatic or aromatic ring can be formed. The cyclometalated transition metal compound according to claim 2, wherein the dianionic tetradentate ligand is any one selected from the group consisting of ligands represented by the following formulas:

3. The cyclometallated transition metal compound according to claim 1 or 2, wherein M is Ru, Rh, Os, Ir, Pt or Au. 10. The cyclometalated transition metal compound according to claim 9, wherein M is Ir. The cyclometalated transition metal compound according to claim 1, wherein the transition metal compound of Formula 1 or Formula 2 is any one of compounds represented by the following Formulas 4 to 10: <Formula 4> <Formula 5>

<Formula 6>

<Formula 7> <Formula 8>

The cyclometalated transition metal compound according to claim 2, wherein the transition metal compound of Formula 3 is any one of compounds represented by the following formula: <Formula 7>

<Formula 8>

In an organic electroluminescent device comprising an organic film between a pair of electrodes, The organic electroluminescent device according to any one of claims 1 to 12, wherein the organic film comprises a cyclometalated transition metal compound according to any one of claims 1 to 12. The organic electroluminescent device according to claim 13, wherein the organic film further comprises at least one selected from the group consisting of at least one polymer host, a mixture of a polymer host and a low molecular host, a low molecular host, and a non-luminescent polymer matrix. . The organic electroluminescent device according to claim 13, wherein the organic layer further comprises a green light emitting material or a blue light emitting material.

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