KR100596132B1 - Phenyl pyridine-iridium metal complex compounds for organic electroluminescent device, process for preparing thereof and organic electroluminescent device using thereof - Google Patents

Abstract

The present invention relates to a phenylpyridine-iridium metal complex compound represented by the following Chemical Formula 1, a method for preparing the same, and an organic electroluminescent device using the same. The light emitting material of the present invention and the organic electroluminescent device using the same provide excellent luminous efficiency and driving life.

Wherein R ₁ to R ₈ , A ₁ and Py are as defined in the specification.

Organic Electroluminescence, Phenylpyridine-Iridium

Description

Phenyl pyridine-iridium metal complex compounds for organic electroluminescent device, process for preparing etc and organic electroluminescent device using

1 is a cross-sectional view of an organic electroluminescent device according to an embodiment of the present invention.

2 is an absorption spectrum represented by using the compound of Formula 1, Ir-1 according to an embodiment of the present invention.

3 is an absorption spectrum represented by using the compound of Formula 1, Ir-2, according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: glass substrate 2: first electrode

3: hole transport layer 4: organic light emitting layer

5: hole blocking layer 6: electron transport layer

7: electron injection layer 8: second electrode

The present invention relates to a light emitting material for an organic electroluminescent device, and more particularly to a phenylpyridine-iridium metal complex compound represented by the formula (1) and a method for producing the same.

[Formula 1]

Where

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , and R ₈ are each independently hydrogen, a straight or branched chain alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen 5- to 18-membered aromatic heterocycles containing one or more heteroatoms selected from the group consisting of a group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, or N, O and S Represents a group,

A ₁ is each independently selected from the group consisting of a linear or branched alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, a carbonyl group or N, O and S; A 5-18 membered aromatic heterocyclic group containing at least one heteroatom,

Py represents substituted or unsubstituted pyridine or isoquinoline

The present invention also provides an organic electroluminescent device containing the compound of Formula 1, and more particularly, at least one of the constituent layers of the organic thin film layer contains at least one compound represented by Formula 1 An organic thin film layer comprising an organic electroluminescent device is provided between a first electrode (anode) and a second electrode (cathode).

Recently, as the development of the information and communication industry is accelerated, higher performance is required in the field of display devices, which is one of the most important fields. Such displays may be classified into light emitting and non-light emitting types. The light emitting display includes a cathode ray tube (CRT), an electroluminescence display (ELD), a light emitting diode (LED), or a plasma display panel (PDP). The non-light emitting display includes a liquid crystal display (LCD).

The light emitting and non-light emitting displays have respective basic performances such as operating voltage, power consumption, brightness, contrast, response speed and lifespan. However, among these, the liquid crystal display, which is a non-light emitting display that has been widely used to date, has problems in response speed, contrast, and visual dependence among the above basic performances. In this situation, the display using the light emitting diode has a fast response time and does not need a back light because it is a self-luminous type, and it has excellent brightness and has various advantages, thus complementing the problems of the liquid crystal display. It is expected to take place as an element. However, since the light emitting diode mainly uses an inorganic material having a crystalline form, it is difficult to be applied to a large area electroluminescent device, requires a high driving voltage of 200 V or more, and has a disadvantage of being expensive.

The research on electroluminescent devices using organic materials in addition to the inorganic electroluminescent devices as described above was actively conducted in 1987 by Eastman Kodak, when a device manufactured from a material having a π-conjugated structure called alumina quinone was released. Done

The organic electroluminescent device is a self-luminous device that electrically excites fluorescent organic compounds and emits light, and is superior to inorganic electroluminescent devices in that it is capable of multi-color light emission with low driving voltage, high brightness, high-speed response, wide viewing angle, surface emission, and thinness. With its features, applications are expected in full-color flat panel displays.

For the organic electroluminescent device, in 1987, C. W. Tang et al. Reported the device having practical performance for the first time (Applied Physics Letters, Vol. 51, No. 12, 913-915 (1987)). The document describes a structure in which a thin film (hole transport layer) of a diamine derivative and a thin film (electron transport light emitting layer) of Alq3 (tris (8-hydroxy-quinolate) aluminum) are laminated as an organic layer. By using such a laminated structure, it is possible to lower the barrier of injection of electrons and holes from the electrode to the organic layer, and to increase the probability of recombination of electrons and holes inside the organic layer.

Subsequently, C. Adachi et al. Consisted of a three-layer structure of a hole transporting layer, a light emitting layer, and an electron transporting layer (Japanese Journal of Applied Physics, Vol. Optimize device characteristics by designing an organic electroluminescent device with an organic layer of a layered structure (Applied Physics Letter, Vol. 55, No. 1589-1491 (1989)), and building a multilayer structure suitable for proper material selection and combination It can be shown.

A normal organic electroluminescent element can be comprised with a 1st electrode (anode), a 2nd electrode (cathode), and an organic light emitting medium. In addition to the light emitting layer, the organic light emitting medium may include two separate organic layers, that is, one layer for injecting and transporting electrons and another layer for injecting and transporting holes in the device. The layer for injecting and transporting electrons and the layer for injecting and transporting holes may be divided into an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer, respectively.

The organic EL device having a simple structure can be composed of a first electrode / electron transport layer and a light emitting layer / second electrode. In addition, each organic functional layer may be separated to constitute a first electrode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / second electrode.

The driving principle of the organic EL device having the structure as described above is as follows.

When a voltage is applied between the anode and the cathode, holes (holes) injected from the anode move 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. The excitons change from the excited state to the ground state, whereby the fluorescent molecules in the light emitting layer emit light to form an image.

Currently, the material generally used as the hole transport layer is a triphenylamine derivative. In addition, organometallic complex compounds or heterocyclic compounds are used for the electron transport layer. In the light emitting layer, an organic compound or an organometallic complex compound is used alone or as a host of the light emitting layer. When an organic compound or an organometallic complex compound is used as a host of the light emitting layer, the emission color may be controlled by doping the organic light emitting material or the metal complex organic light emitting material with a dopant.

The internal quantum efficiency of the organic electroluminescent device is expressed as the ratio of photons generated inside the device to the number of charges injected from the external electrode. If the quantum efficiency can be improved, the lifetime of the device can be increased. In general, fluorescence is what emits light when a molecule falls from the singlet excited state to the ground state, and phosphorescence is what emits light when it falls from the triplet excited state to the ground state. The maximum efficiency at which molecules will emit light from an excited state is 25% for fluorescence and 75% for phosphorescence. Therefore, many studies have been made to extend the life of the device by introducing a phosphor having such a high luminous efficiency into an organic thin film layer of the organic electroluminescent device, preferably the light emitting layer, but no suitable material has been developed.

One method for the practical use of such a full-color display is to develop a material having a high luminous efficiency to be applied to an organic thin film layer, preferably a light emitting layer of an organic EL device. Currently, research is being conducted on iridium metal complex organic compounds which are phosphors as high efficiency light emitting materials for organic electroluminescent devices. Organic electroluminescent devices using this material as the dopant of the light emitting layer are known to have high luminous efficiency when driven (Nature, 403, 750-753 (2000)).

The iridium metal complex organic compound constituting the light emitting layer has a light emission color depending on the molecular structure of the ligand. In this case, the light emitting layer may use only an iridium metal complex organic compound that is a phosphor, or may include an iridium metal complex organic compound that is another phosphor as a dopant.

Accordingly, it is an object of the present invention to provide a novel phenylpyridine-iridium metal complex compound and a method for producing the same for use in an organic electroluminescent device.

In addition, the present invention provides a light emitting region characterized in that the organic electroluminescent device containing the light emitting material, more specifically, at least one layer of the constituent layer of the organic thin film layer contains at least one compound represented by the formula (1). An object of the present invention is to provide an organic electroluminescent device comprising an organic thin film layer provided between a first electrode (anode) and a second electrode (cathode).

In order to achieve the above object, the present invention provides a phenylpyridine-iridium metal complex compound which is a light emitting material for an organic electroluminescent device represented by the following formula (1).

[Formula 1]

Where

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , and R ₈ are each independently hydrogen, a straight or branched chain alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen 5- to 18-membered aromatic heterocycles containing one or more heteroatoms selected from the group consisting of a group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, or N, O and S Represents a group,

A ₁ is each independently selected from the group consisting of a linear or branched alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, a carbonyl group or N, O and S; A 5-18 membered aromatic heterocyclic group containing at least one heteroatom,

Py is each independently a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, or N Pyridine or isoquinoline substituted or unsubstituted with a 5 to 18 membered aromatic heterocyclic group containing at least one heteroatom selected from the group consisting of O, S and.

Preferred compounds of the formula 1 are specifically illustrated below, but the present invention is not limited to the following representative examples.

Substituents of the compound of Formula 1 may be each substituted by a linear or branched alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, but are not limited thereto.

The present invention also provides a method for preparing the compound of Formula 1.

Compound of Formula 1 is

1) reacting a substituted phenylpyridine compound of formula 2 with IrCl ₃ * xH ₂ O or Na ₃ IrCl ₆ * xH ₂ O to obtain a precursor (wherein x represents a range of 1 to 3, respectively) ; And

2) The precursor obtained in step 1) may be prepared by reacting the compound of Formula 3 to obtain a compound of Formula 1.

Wherein Py and A ₁ are as defined above,

R ₉ to R ₁₃ are each independently hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, and 5 to 18 carbon atoms. Or a cycloalkyl group of 5 to 18 membered aromatic heterocyclic group containing at least one heteroatom selected from the group consisting of N, O and S.

In the first step of the preparation method, the reaction temperature is 0 degrees Celsius to 140 degrees Celsius, preferably 100 degrees to 135 degrees Celsius, and the reaction time is 1 to 240 hours, preferably 10 to 48 hours. As the solvent, a general organic solvent used for a chemical reaction may be used, but preferably alcohol derivatives, and more preferably 2-ethoxyethanol may be used.

In addition, the amount of the iridium complex compound relative to the compound of the formula (2) may be used in a molar ratio of 0.0001 to 10 times, preferably a molar ratio of 0.1 to 1 times.

In the second step of the preparation method, the reaction temperature is 0 degrees Celsius to 140 degrees Celsius, preferably 100 degrees to 135 degrees Celsius, and the reaction time is 0.01 hours to 240 hours, preferably 0.1 hours to 10 hours As the solvent, a conventional organic solvent used in a chemical reaction may be used, but preferably alcohol derivatives, and more preferably 2-ethoxyethanol may be used. The amount of the compound of formula 3 relative to the precursor of the iridium complex compound obtained in step 1 may be used in a molar ratio of 0.01 to 100 times, preferably 0.1 to 5 times. As the basic material used for the reaction, metal oxides, metal hydroxides, metal carbonates may be used, preferably metal carbonates, and more preferably K ₂ CO ₃ may be used.

For example, the manufacturing process of the compound of Formula 1 described above will be described as follows. Other compounds belonging to Formula 1 may be prepared by a process similar to the following.

The present invention also relates to an organic electroluminescent device containing the above-described light emitting material, and more particularly to an organic electroluminescent device in which an organic thin film layer including a light emitting region is provided between a first electrode (anode) and a second electrode (cathode). It provides an organic electroluminescent device, characterized in that at least one of the constituent layers of the organic thin film layer contains at least one light emitting material according to the present invention.

The compound of formula 1 according to the present invention may be used alone or as a mixture in any of the above organic thin film layers, or may be used as a host in these layers, and may be doped with other hole transport materials, light emitting materials, or electron transport materials as dopants. It may be. Preferably, the compound according to the present invention can be used alone or as a dopant in the light emitting layer.

Various embodiments are possible for an organic EL device manufactured using the light emitting material of the present invention. Basically, a light emitting layer is inserted between a pair of electrodes (anode and cathode), and a hole injection layer and / or a hole transport layer and / or an electron injection layer and / or an electron transport layer are inserted therein as necessary. Specifically, for example, the structure thereof includes (1) an anode / light emitting layer / cathode; (2) anode / hole transport layer / light emitting layer / cathode; (3) anode / hole injection layer / hole transport layer / light emitting layer / cathode; (4) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode; (5) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode; (6) anode / hole injection layer / light emitting layer / electron injection layer / cathode; And (7) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode. It is preferable that each element which has the said structure is supported by a board | substrate. There is no particular limitation on the substrate, and those conventionally used in organic electroluminescent devices may be used, for example, glass, transparent plastic, quartz or the like.

The shaping | molding method of each layer which comprises the organic electroluminescent element of this invention can be formed by thinning by applying a well-known method, for example, a vapor deposition method, a spin coat method, a cast method, etc. according to the material which comprises each layer.

The film thickness of each of the layers thus formed, for example, the light emitting layer, is not particularly limited and can be appropriately selected depending on the situation.

As the anode in the organic electroluminescent device of the present invention, a metal, an alloy, an electrically conductive compound having a large work function of 4.0 eV or more, or a mixture thereof can be used as the electrode material. Examples of such an electrode material include conductive transparent or opaque materials such as ITO, SnO ₂ , ZnO, Au, and the like, which may be manufactured by forming a thin film by performing a method such as deposition or sputtering of the electrode material described above. have.

On the other hand, as the cathode, metals, alloys, electroconductive compounds, and mixtures thereof having a work function of 4.2 eV or less can be used as the electrode material. Examples of such electrode materials include calcium, magnesium, lithium, aluminum, magnesium alloys, lithium alloys, aluminum alloys, aluminum / lithium mixtures, magnesium / silver mixtures, indium and the like. Such a cathode can be produced by forming a thin film by applying a method such as vapor deposition, sputtering, or the like to these electrode materials. In addition, the sheet resistance as the electrode is preferably several hundred? / Mm or less, and the film thickness is usually selected in the range of 10 nm to 1 m, preferably 50 to 200 nm.

In the organic electroluminescent device of the present invention, it is preferable that one or both of the anode and the cathode are made transparent or semitransparent, and the light emission is transmitted to improve the light emission efficiency.

Other hole injection materials and hole transport materials that can be used in the organic electroluminescent device of the present invention include those conventionally commonly used as charge transport materials for holes in photoconductive materials, or hole injection layers for organic electroluminescent devices; Any of known materials used for the hole transport layer may be selected and used.

The electron transport layer in the organic electroluminescent element of the present invention contains an electron transport compound and has a function of transferring electrons injected from the cathode to the light emitting layer. There is no restriction | limiting in particular about such an electron transfer compound, Arbitrary thing can be selected and used out of a conventionally well-known compound.

Hereinafter, a synthesis example of the phenylisoquinoline-iridium metal complex compound of the present invention and an organic electroluminescent device to which the compounds are applied will be described in detail in the following Synthesis Examples and Examples. It is not limited, It can change and implement in various ways within the scope of the invention as described in an attached claim.

Synthesis Example 1

Synthesis of Precursors of Substituted Iridium Complexes

First, 1-chloro-isoquinoline (3.0g, 18mmmol), phenylboronic acid (2.7g, 21mmol), tetrakis-triphenylphosphine palladium (1.6g, 0.8mmol%) and potassium carbonate in 100ml reaction vessel (2.9 g, 21 mmol) was added thereto, and a solvent ethylene-glycol-dimethyl-ether (50 ml) purified under nitrogen stream was added thereto, and the mixture was refluxed at 90 ° C. for 12 hours. After the temperature was lowered to room temperature, the mixture was extracted with chloroform and distilled water and separated by column chromatography (chloroform: hexane = 1: 3) to obtain 3.32 g (90%) of 1-phenyl-isoquinoline.

1-phenyl-isoquinoline (900 mg, 4.4 mmol) and Na ₃ IrCl ₆ * 3H ₂ O (947.8 mg, 2.0 mmol) were added to a 100 ml reaction vessel, and 30 ml of 2-ethoxyethanol purified solvent under nitrogen stream The reaction was refluxed at 110 degrees Celsius for 12 hours. After cooling to room temperature, 15 ml of distilled water was added, and the obtained precipitate was filtered through a glass filter of G4 size, and then washed with methanol (15 ml) and ethyl ether (15 ml). This precipitate was dried to obtain a precursor of the iridium complex compound.

Synthesis Example 2

Synthesis of Iridium Complex Compound (Ir-1)

In a 50 ml reaction vessel, the precursor (900.0 mg, 0.7 mmol) prepared in Synthesis Example 1, 2-acetyl-1,3-cyclohexanedione (218 mg, 1.4 mmol), and K ₂ CO ₃ (100 mg) were added to a nitrogen stream. 30 ml of 2-ethoxyethanol purified solvent was added thereto, and the mixture was refluxed at 110 degrees Celsius for 1 hour. After the temperature was lowered to room temperature, the precipitate was filtered through a glass filter of G4 size, and the precipitate was washed with MeOH (15 ml) and recovered. The synthesized material was sublimed and purified using a vacuum sublimation apparatus for use in an organic electroluminescent device. The obtained material was confirmed by molecular structure using NMR and mass spectrometry, and the analysis results confirmed that the compound of Ir-1 was synthesized.

NMR analysis ( ¹ H NMR (CDCl ₃ )): δ 9.06-6.36 (m, aromatic 20H), 2.34 (s, 2CH ₂ -CO, 4H), 1.55 (s, CH ₃ -CO, CH ₂ CH ₂ CH _{2 .} 5H)

Mass Analysis: Calculated Value: 756, Experimental Value: 756

Example

A first electrode ITO was formed to a thickness of 100 nm on the transparent substrate, and 50 nm thick using NPD (N, N-dinaphthyl-N, N-phenyl- (1,1-biphenyl) -4,4-diamine) thereon. To form a hole transport layer. Next, an organic light emitting layer was deposited to a thickness of 30 nm using CBP (4,4-Bis (carbazole-9-yl) -biphenyl). At this time, 10% of compound Ir-1 was added as a dopant. BCP (2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline) was used to form a hole blocking layer with a thickness of 5 nm, and Alq3 (tris (8-hydroxy-quinolate) aluminum) was used. An electron transport layer was deposited to a thickness of 30 nm. Thereafter, an electron injection layer made of an alkali metal LiF having a thickness of 0.3 nm was formed, and a second electrode Al having a thickness of 100 nm was coated.

Luminescent characteristics were evaluated by applying a forward bias DC voltage to the organic electroluminescent device of Example 1 thus produced. The emission color was red, and spectroscopic measurements were carried out to obtain a spectrum having an emission peak near 612 nm. Moreover, when voltage-luminance measurement was performed, the brightness | luminance of 3,400 cd / m <2> was obtained at 8V, and the efficiency at this time was 1.35 lm / W.

The organic electroluminescent device to which the luminescent material of the present invention is applied exhibits excellent luminous efficiency and brightness as compared to a device to which a known luminescent material is applied, and contributes to improving the stability of the device and increasing the life of the device.

Claims (7)

A compound of formula 1 [Formula 1]

Where R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , and R ₈ are each independently hydrogen, a straight or branched chain alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen 5- to 18-membered aromatic heterocycles containing one or more heteroatoms selected from the group consisting of a group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, or N, O and S Represents a group, A ₁ is each independently selected from the group consisting of a linear or branched alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, a carbonyl group or N, O and S; A 5-18 membered aromatic heterocyclic group containing at least one heteroatom, Py is each independently a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, a cycloalkyl group having 5 to 18 carbon atoms, or N Pyridine or isoquinoline substituted or unsubstituted with a 5 to 18 membered aromatic heterocyclic group containing at least one heteroatom selected from the group consisting of O, S and. The compound of claim 1 wherein: Ir-1 or Ir-2.

1) reacting a compound of Formula 2 with IrCl ₃ * xH ₂ O or Na ₃ IrCl ₆ * xH ₂ O to obtain a precursor (wherein each x represents a range of 1 to 3); And 2) A process for preparing the compound of formula 1 according to claim 1, wherein the precursor obtained in step 1) is reacted with a compound of formula 3 to obtain a compound of formula 1. [Formula 2]

[Formula 3]

Wherein, _Py, and A ₁ are as defined in claim 1, R ₉ to R ₁₃ are each independently hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen group, a substituted or unsubstituted aromatic group having 5 to 18 carbon atoms, and 5 to 18 carbon atoms. Or a cycloalkyl group of 5 to 18 membered aromatic heterocyclic group containing at least one heteroatom selected from the group consisting of N, O and S. At least one of the constituent layers of the organic thin film layer contains at least one compound represented by the formula (1) according to claim 1 or claim 2 wherein the organic thin film layer comprising a light emitting region comprises a first electrode (anode) and The organic electroluminescent element provided between 2nd electrode (cathode). The organic electroluminescent device according to claim 4, wherein the organic thin film layer has a multilayer structure including a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, or an electron injection layer. The organic electroluminescent device according to claim 5, wherein at least one compound according to claim 1 or 2 is used as a dopant of the light emitting layer. The organic electroluminescent device according to claim 5, wherein at least one compound according to claim 1 or 2 is used as a host of the light emitting layer.

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