KR101105242B1 - Solution Processable Blue Iridium Complex with Picolinic acid or Picolinic acid-N-oxide Derivatives Ancillary Ligand and Organic Light-Emitting Diodes Containing Iridium Complex - Google Patents

Abstract

In the present invention, an aryl derivative substituted with a halogen compound and a pyridine derivative introduced with an alkyl or alkoxy substituent are introduced as a main ligand, and an alkyl, alkyloxyalkoxy, alkylamine, arylamine or aminoalkylamine derivative is used as an auxiliary ligand. The present invention also provides a phosphorescent organic electroluminescent device comprising a light emitting layer introduced at carbon 4 of picolinic acid-N-oxide as a dopant of an iridium complex compound capable of forming a thin film by a solution process and a light emitting layer into which the iridium complex compound is introduced. The iridium complex for the solution process synthesized by the main and secondary ligands introduced into the iridium according to the present invention can be formed by doping the iridium complex compound into the light emitting layer because the solubility is increased so that the light emitting layer can be formed by the solution process instead of vacuum deposition. In addition to the large-area, it is possible to obtain a device having a greatly improved efficiency in the manufacturing process compared with the prior art of manufacturing a device by vacuum deposition.

Iridium Complex, Solution Process, 4-alkoxypicolinic acid, 4-alkyloxyalkoxypicolinic acid, 4-alkylaminepicolinic acid, 4-arylaminepicolinic acid, 4-aminoalkylaminepicoli Nicnic acid, 4-alkoxypicolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide, 4-alkylaminepicolinic acid-N-oxide, 4-arylaminepicolinic acid-N-oxide, 4-Aminoalkylamine picolinic acid-N-oxide organic electroluminescent device (OLED)

Description

Iridium blue light-emitting compound having a picolinic acid or picolinic acid-en-oxide derivative capable of solution processing as an auxiliary ligand, and an organic electroluminescent device comprising the same (Solution Processable Blue Iridium Complex with Picolinic acid or Picolinic acid-N-oxide) Derivatives Ancillary Ligand and Organic Light-Emitting Diodes Containing Iridium Complex}

The present invention relates to an iridium complex and an organic semiconductor device including the same. More specifically, examples thereof include a blue iridium complex and an iridium complex having an appropriate ligand having excellent solubility in a solvent so as to form a thin film by a solution process. For example, the present invention relates to an organic light emitting device introduced into a dopant of a light emitting layer.

Recently, as the size of display devices increases, the demand for flat display devices such as liquid crystal displays (LCDs) and plasma display panels (PDPs) is increasing. These flat display devices have slower response speeds and limited viewing angles compared to cathode ray tubes (CRTs). Therefore, studies on other display devices are being conducted. One of them is an electroluminescent device.

Conventional electroluminescent devices have mainly used inorganic electroluminescent devices using the light emission phenomenon that occurs when an electric field is applied to an inorganic semiconductor made of a pn junction such as ZnS, Cas, etc. However, in the case of inorganic electroluminescent devices, the driving voltage is higher than AC 220V. There is a problem that it is difficult to increase the size because the device is manufactured in a vacuum state, and in particular, it is difficult to obtain blue with high efficiency.

Due to these problems, organic light-emitting diodes (OLEDs) using organic materials, which can realize colors through appropriate power sources rather than inorganic materials, have been developed. As such organic electroluminescent devices, vacuum deposition type organic electroluminescent devices have been proposed by Tang et al. Of Eastman Kodak (CW Tang and SA VanSlyke, Organic electroluminescent diodes, Applied Physics Letters , vol. 51, issue 12, 913-915, 1987), by reporting Polymer Light-Emitting Diodes (PLEDs) using conjugated polymers, it has been shown that organic electroluminescent devices can be fabricated through a solution process rather than vacuum deposition (JH). Burroughes, DDC Bradley, AR Brown, RN Marks, K. Mackay, RH Friend, PL Burns, and AB Holmes, Light-Emitting Diodes Based on Conjugated Polymers, Nature, vol. 347, issue 6293, 539-541, 1990).

In general, the organic light emitting device is a display using an organic material that emits light by itself, and when an electric field is applied to the organic material, electrons and holes are transferred from the cathode and the anode, respectively, to be combined within the organic material. At this time, the generated energy uses the organic electroluminescence emitted as light. That is, the organic light emitting display device has a structure in which a thin film is inserted into an organic material capable of emitting light between two electrodes. The organic light emitting diode is classified into a vacuum deposition type and a solution process type according to how the organic thin film is formed.

The organic light emitting display device is not only able to realize a very thin screen due to the characteristics of the device structure, but also has a good response speed because it emits light, and has a good viewing angle and low power consumption. can do. In particular, the organic EL device manufactured through the solution process is suitable for low-cost mass production through a flexible device such as a roll and a printing process. Therefore, the organic light emitting display device is attracting attention as a next generation flat panel display device instead of the liquid crystal display device in the flat panel display industry, which is currently dominated by liquid crystal display (LCD).

The phenomenon of light emission in such an organic light emitting device can be classified into fluorescence and phosphorescence. When fluorescence is emitted from an organic molecule to a ground state from a singlet excited state, it emits light. Phosphorescence is a phenomenon in which organic molecules emit light when they fall from the triplet excited state to the ground state.

This will be described in detail as follows. Organic compounds doped in organic electroluminescent devices, including the light emitting layer, share electrons between atomic carbon and other carbon atoms, or between atomic carbon and other atoms to form molecules through covalent bonds. Atomic electron orbits (atomic orbital, AO) are converted to molecular orbitals (molecular orbital, MO). In molecular electron orbits, two pairs of atomic orbitals in the atomic state each participate to form a bonding orbital and an antibonding orbital, respectively. At this time, the band formed by many coupling orbits is called a valence band, and the die formed by many anti-bonding orbits is called a conduction band. The highest energy level of the valence band is called HOMO. The highest energy level of the conductive band is called Lowest Unoccupied Molecular Orbital (LUMO), and the energy difference between the energy of HOMO and LUMO is called the band gap.

However, electrons and holes injected into the organic light emitting layer constituting the organic light emitting device are recombined to form excitons, and the color of the color corresponding to the energy band gap of the light emitting layer in the process of converting the electrical energy of the excitons into light energy. Implement light. In this process, a single spin exciton with zero spin and triplet exciton with a spin of 1 are generated at a ratio of 1: 3. According to the selection rule for the electric dipole transition, the spin quantum number should not be changed when transitioning from the excited state to the ground state. Since the ground state of the organic molecules is the singlet state, the singlet excitons emit light and transition to the ground state. However, triplet excitons can't glow and transition. Therefore, in general, the maximum internal quantum efficiency is limited to 25% in the case of organic electroluminescent devices doped with fluorescent dyes. However, if the spin-orbital coupling is large, the triplet excitons are phosphorescent to the ground state because the inter-system crossing occurs between the singlet and triplet states by mixing the singlet form and the triplet state. Can make a transition. After all, if the triplet excitons can be used to emit light, the internal quantum efficiency of the organic light emitting device can theoretically be improved to 100%.

Phosphorescent organic electroluminescent devices that can dramatically improve the luminous efficiency of organic electroluminescent devices were developed by SR Forrest professor of Princeton University and ME Thompson professor of USC in 1999 (MA Baldo). , S. Lamansky, PE Burrows, ME Thompson and SR Forrest, Very high-efficiency green organic light-emitting devices based on electrophosphorescence, Applied Physics Letters , vol. 75, issue 1, 4-6, 1999), in particular spin-orbit Since the bond is proportional to the square of the atomic number, it is known that a complex of heavy atoms such as platinum (Pt), iridium (Ir), europium (Eu), terbium (Tb) and the like has high phosphorescence efficiency. In the case of platinum complexes, the lowest triplet excitons are ligand-centered excitons (LC excitons), while the iridium complexes have the lowest energy triplet excitons. ligand charge transfer (MLCT). Thus, iridium complexes form larger spin-orbit bonds than platinum complexes, resulting in much shorter triplet exciton lifetimes and high phosphorescence efficiencies.

In this regard, C. Adachi et al. Described bis (2-phenylpyridine) iridium (III) acetylacetonate [(ppy) ₂ Ir (acac)], a green phosphorescent pigment with iridium as its central metal, with 3-phenyl-4- (1'- An organic electroluminescent device with a maximum luminous efficiency of 60 lm / W and a maximum internal quantum efficiency of 87% has been announced by doping naphthyl) -5-phenyl-1,2,4-triazole (TAZ). In addition, U.S. Universal Display Corp. (UDC) has announced that it has achieved high luminous efficiency of 82 lm / W by doping such a green phosphorescent dye into the light emitting layer and using a hole injection material developed by LG Chem.

As described above, phosphorescent organic light emitting diodes emitting green and red light have been developed, but blue phosphorescent organic light emitting diodes having excellent luminous efficiency, color coordinates, and lifetimes have not been developed. For example, Flrpic (Iridium (III) bis [2,2 '(4'-difluorophenyl) -pyridinato-N, C2'] picolinate) has been developed recently, but it is still not a pure blue light emitting material in terms of color purity. There is a crowd. In particular, conventional blue phosphorescent organic light emitting diodes mostly form a light emitting layer by vacuum deposition, and there are no blue phosphorescent organic light emitting diodes that can form a light emitting layer by a solution process.

The present invention has been proposed to solve the above problems, an object of the present invention is to improve the solubility of the blue phosphorescent light emitting material and UV-visible, PL and EL spectral characteristics that were developed for the conventional vacuum deposition, for example It is an object of the present invention to provide an iridium complex compound capable of forming a light emitting layer by a solution process and an organic electroluminescent device and a method of manufacturing the light emitting device including such an iridium complex compound in a light emitting layer.

Another object of the present invention is to provide an organic light emitting device capable of forming a thin film through a solution process and an improved manufacturing process, and a method of manufacturing the organic light emitting device.

Other objects and advantages of the present invention will become more apparent from the following drawings and the configuration of the invention.

According to one aspect of the present invention having the above object, there is provided an iridium complex compound represented by the following formula (1).

Formula 1

는 4-알콕시피콜리닉산, 4-알킬옥시알콕시피콜리닉산, 4-알킬아민피콜리닉산, 4-아릴아민피콜리닉산, 4-아미노알킬아민피콜리닉산, 4-알콕시피콜리닉산-N-옥사이드, 4-알킬옥시알콕시피콜리닉산-N-옥사이드, 4-알킬아민피콜리닉산-N-옥사이드, 4-아릴아민피콜리닉산-N-옥사이드, 4-아미노알킬아민피콜리닉산-N-옥사이드이다.)In Formula 1, R ₁ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms; Ar is an aryl group; R ₂ is halogen, R ₃ is hydrogen or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms ;

Is 4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid, 4-alkylamine picolinic acid, 4-arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxy picolinic acid-N -Oxide, 4-alkyloxyalkoxypicolinic acid -N-oxide, 4-alkylaminepicolinic acid -N-oxide, 4-arylaminepicolinic acid -N-oxide, 4-aminoalkylaminepicolinic acid -N Oxides.)

In this case, R ₁ of Formula 1 is an alkyl group having 1 to 10 carbon atoms, and the aryl group is phenyl, naphthalene, fluorene, fluorene, carbazole, phenazine, phenanthroline ), Phenanthridine, acridine, acinnoline, cinnoline, quinazoline, quinoxaline, naphthydrine, phthalazine, quinolazine (quinolizine), indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyridine, pyrazole, imidazole (imidazole) and pyrrole, and R ₃ in Formula 1 may be an alkyl group having 1 to 10 carbon atoms substituted with halogen, and R ₂ in Formula 1 may be fluorine or chlorine. It is done.

On the other hand, according to another aspect of the present invention, there is provided an organic electroluminescent device in which the above-mentioned iridium complex compound is included in the light emitting layer.

According to an aspect of the present invention, the organic light emitting device includes a first electrode and a second electrode formed to face the first electrode, wherein the light emitting layer is stacked between the first electrode and the second electrode It is characterized by being.

According to another aspect of the present invention, the buffer layer may further include a buffer layer between the first electrode and the light emitting layer, and an electron transport layer and an electron injection layer between the light emitting layer and the second electrode, wherein the buffer layer is the first electrode. And a hole injection layer stacked on top of the hole injection layer, and a hole transport layer stacked on top of the hole injection layer.

In particular, the iridium complex according to the present invention may be included as a dopant of the light emitting layer, in which case the iridium complex is characterized in that it is contained in a concentration of 3 to 20% by weight based on the total amount of the light emitting layer.

Furthermore, according to another aspect of the present invention, there is provided a method of manufacturing an organic electroluminescent device comprising the step of laminating a light emitting layer containing the above-mentioned iridium complex compound to the upper portion of the first electrode.

In this case, the light emitting layer may be stacked on top of the first electrode by a solution process, and the light emitting layer may be stacked on top of the first electrode with a thickness of 5 to 200 nm.

The solution process iridium complex synthesized according to the present invention has a similar UV-visible, PL and EL spectra compared to the blue iridium-based light emitting material, greatly improved light emission color and solubility, and can be easily dissolved in an organic solvent. The area can be produced.

That is, the iridium complex for the solution process of the present invention introduces a pyridine derivative substituted with an alkyl or alkoxy group and a phenyl derivative substituted with a halogen compound, and especially 4-alkoxy picolinic acid, 4-alkyloxyalkoxy as a secondary ligand. Picolinic acid, 4-alkylaminepicolinic acid, 4-arylaminepicolinic acid, 4-aminoalkylaminepicolinic acid, 4-alkoxypicolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N A blue iridium-based light emitting material conventionally known by introducing an oxide, 4-alkylamine picolinic acid-N-oxide, 4-arylamine picolinic acid-N-oxide, and 4-aminoalkylamine picolinic acid-N-oxide; In comparison, as a material capable of forming a light emitting layer by a solution process, it may be used as a dopant of a light emitting layer to manufacture a blue phosphorescent organic light emitting device.

In addition, the iridium complex compound of the present invention is soluble in general organic solvents and improves heat resistance characteristics by introducing various types of substituents into pyridine derivatives substituted with alkyl or alkoxy groups introduced into the main ligand and phenyl derivatives substituted with halogen compounds. In addition, it can be used as a light emitting material having excellent interfacial properties with the electrode and excellent thin film properties.

The present inventors completed the present invention while developing compounds that can be used in organic semiconductor devices, for example, organic electroluminescent devices, which are less complicated in the manufacturing process through the solution process rather than the vacuum deposition method while improving the luminous efficiency. EMBODIMENT OF THE INVENTION Hereinafter, the technical idea of this invention is demonstrated with reference to attached drawing.

As described above, in the organic electroluminescent device, it is advantageous to use the light emitting material having the phosphorescence property rather than the light emitting material having the fluorescent property in terms of luminous efficiency and the like, and not into the conventional vacuum deposition method but into the device by the solution process. It is preferable that an organic thin film can be formed. In other words, the manufacturing process of the device is less complicated when the device is manufactured through a solution process such as inkjet printing or screen printing in the organic semiconductor manufacturing because it does not have to go through steps such as vacuum deposition and photo-lithography. In addition to easy and large-area processing, it can be applied to flexible substrates and ultra-low cost manufacturing. Therefore, if the device can be formed by such a solution process, it can be applied not only to a driving device of a next-generation flexible substrate but also to a so-called 'e-book' and an electronic information tag (RFID).

In the present invention, among the blue light emitting materials having such phosphorescence properties, especially the existing blue phosphorescent iridium complexes and UV-visible, PL and EL spectral characteristics are improved, the emission color and solubility are greatly improved, and the solubility is improved, so as to improve compatibility with the host. An organic electroluminescent device comprising an excellent iridium complex for solution processing and an iridium complex for solution processing has been developed.

In the iridium complex according to the present invention, aromatic aryl derivatives and pyridine derivatives are introduced as main ligands, and 4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid, 4-alkylamine picolinic acid, 4 are introduced as auxiliary ligands. -Arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxy picolinic acid -N-oxide, 4-alkyloxyalkoxy picolinic acid -N-oxide, 4-alkylamine picolinic acid -N- Oxides, 4-arylaminepicolinic acid-N-oxides, 4-aminoalkylaminepicolinic acid-N-oxides were introduced. Accordingly, when the light emitting layer is formed by a solution process as compared with a conventionally known iridium-based light emitting material, when used as a dopant of the light emitting layer, a large area organic light emitting device for blue phosphorescence can be manufactured. According to a preferred embodiment, the iridium complex synthesized in the present invention has a structure of formula (1).

Formula 1

는 4-알콕시피콜리닉산, 4-알킬옥시알콕시피콜리닉산, 4-알킬아민피콜리닉산, 4-아릴아민피콜리닉산, 4-아미노알킬아민피콜리닉산, 4-알콕시피콜리닉산-N-옥사이드, 4-알킬옥시알콕시피콜리닉산-N-옥사이드, 4-알킬아민피콜리닉산-N-옥사이드, 4-아릴아민피콜리닉산-N-옥사이드, 4-아미노알킬아민피콜리닉산-N-옥사이드이다.)In Formula 1, R ₁ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms; Ar is an aryl group; R ₂ is halogen, R ₃ is hydrogen or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms ;

Is 4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid, 4-alkylamine picolinic acid, 4-arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxy picolinic acid-N -Oxide, 4-alkyloxyalkoxypicolinic acid -N-oxide, 4-alkylaminepicolinic acid -N-oxide, 4-arylaminepicolinic acid -N-oxide, 4-aminoalkylaminepicolinic acid -N Oxides.)

As can be seen in the above formula (1), the iridium complex according to the present invention is an aromatic pyridine derivative introduced with an alkyl or alkoxy group and an aryl derivative introduced with a halogen compound as a main ligand. In the iridium complex compound exhibiting the phosphorescence property as in the present invention, the main ligand is a main factor for determining the emission color, and in particular, the emission property may be converted according to the electron density of nitrogen (N) contained in the ligand. In the case of the aromatic aryl derivative and the pyridine derivative introduced into the main ligand according to the present invention, the electron density of the nitrogen included in the structure is greatly increased compared to the conventionally developed iridium complex compound, thereby showing pure blue light emission.

The aryl group introduced into the main chain of the iridium complex synthesized according to the present invention includes phenyl, naphthalene, carbazole, fluorene, phenazine, phenanthroline, phenan Tridine (phenanthridine), acridine (acridine), sinoline (cinnoline), quinazoline (quinazoline), quinoxaline, naphthydrine, phthalazine (quintalzine), quinolizine , Indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyridine, pyrazole, imidazole , Pyrrole and the like, preferably phenyl, naphthalene, carbazole, fluorene and the like, but the present invention is not limited thereto.

Meanwhile, the aromatic aryl derivative and the pyridine derivative introduced into the main ligand according to the present invention may be substituted by various substituents such as alkyl groups, alkoxy groups, halogens and the like. As such, the iridium complex compound synthesized according to the present invention due to the substitution of various functional groups may be commonly used in organic solvents used, and when applied to organic electroluminescent devices, the interfacial characteristics with the electrodes may be improved.

In particular, in the context of the present invention, substituents that may be substituted on the aromatic ring linked to pyridine are, for example, straight or branched alkyl groups of 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 20 carbon atoms. It contains 1-10 alkoxy groups. Meanwhile, halogen atoms such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) may be used as substituents on the aryl ring, and preferred halogen atoms include fluorine and chlorine. In addition, according to an embodiment of the present invention, for example, an aryl ring introduced into the main ligand, a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, may be introduced separately from the halogen atom described above. In this case, the alkyl group introduced into the aryl ring may be substituted by a halogen atom such as fluorine or chlorine.

On the other hand, the iridium complex synthesized according to the preferred embodiment of the present invention is an ancillary ligand (ancillary ligand) is introduced separately from the above-described main ligand. The auxiliary ligands are selected to adjust the fine color in the luminescence properties of the synthesized complex compound. In particular, the iridium complex compound for the solution process of the present invention may exhibit pure blue light emission and is preferably formed with less conjugated structure. Do.

)는 용해 가능한 작용기로서, 탄소수 1~10의 알킬기 또는 알콕시기, 바람직하게는 탄소수 1~5의 알킬기 또는 알콕시기가 치환되어 있는 4-알콕시피콜리닉산,4-알킬옥시알콕시피콜리닉산(

), 4-알킬아민피콜리닉산, 4-아릴아민피콜리닉산, 4-아미노알킬아민피콜리닉산, 4-알콕시피콜리닉산-N-옥사이드,4-알킬옥시알콕시피콜리닉산-N-옥사이드(

), 4-알킬아민피콜리닉산-N-옥사이드, 4-아릴아민피콜리닉산-N-옥사이드, 4-아미노알킬아민피콜리닉산-N-옥사이드와 같이, 4번 탄소 위치에 다양한 작용기가 치환되어 있는 피콜리닉산 유도체를 들 수 있다. In addition, a feature of the present invention is a secondary ligand that can be selected in connection with the present invention in which various forms of substituents are introduced into the secondary ligand to improve solubility (

) Is a dissolvable functional group, 4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid (C1-C10 alkyl group or alkoxy group, preferably a C1-C5 alkyl group or alkoxy group is substituted)

), 4-alkylaminepicolinic acid, 4-arylaminepicolinic acid, 4-aminoalkylaminepicolinic acid, 4-alkoxypicolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide (

), 4-alkylaminepicolinic acid-N-oxide, 4-arylaminepicolinic acid-N-oxide, 4-aminoalkylaminepicolinic acid-N-oxide, various functional groups are substituted at the carbon position 4 And picolinic acid derivatives.

4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid, 4-alkylamine picolinic acid, 4-arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxy picolinic acid -N-oxide, 4-alkyloxyalkoxypicolinic acid -N-oxide, 4-alkylaminepicolinic acid -N-oxide, 4-arylaminepicolinic acid -N-oxide, 4-aminoalkylaminepicolinic acid With the introduction of -N-oxide, UV-visible, PL and EL spectral characteristics as well as solubility have been greatly improved compared to the conventional red phosphorescent iridium complex for vacuum deposition, and productivity due to the ease of device fabrication process Can be greatly improved.

In other words, the present invention relates to a blue iridium complex compound capable of a solution process and an organic light emitting device including the same, and more particularly, alkyl, alkyloxyalkoxy, alkylamine so as to greatly improve the thin film formation efficiency by the solution process. Iridium complexes in which a picolinic acid or picolinic acid-N-oxide derivative is introduced into a secondary ligand in which a arylamine or aminoalkylamine derivative is introduced at carbon 4 of picolinic acid or picolinic acid-N-oxide And it relates to an organic light emitting device comprising the same.

Next, the synthesis | combining process of the iridium complex compound which concerns on this invention is demonstrated. 1A is a schematic diagram illustrating a process of synthesizing the iridium complex of Chemical Formula 1 according to an embodiment of the present invention. As shown, first, an aromatic boronic acid ((1)) such as a pyridine derivative ((2)) substituted with an alkyl or alkoxy group having 1 to 20 carbon atoms and a phenylboronic acid substituted with a halogen atom such as fluorine is replaced with K ₂ CO. _The arylpyridine ligand ((3)) is produced by Suzuki synthesis in ₃ and Pd (PPh ₃ ) ₄ and THF solvents. The arylpyridine dimer ((4)) can then be synthesized by dissolving the mixture of the resulting arylpyridine ligand and iridium chloride hydrate (IrCl ₃ · 3H ₂ O) in a suitable solvent and then mixing. Finally, the obtained chlorine-crosslinked dimer ((11)) is 4-chloropicolinic acid or 4-chloropicolinic acid-N-oxide, dibutylaminepicolinic acid, dibutylaminepicolinic acid-N-. Oxides, aminopropylaminepicolinic acid, aminopropylaminepicolinic acid-N-oxide auxiliary ligands and suitable solvents (2-ethoxyethanol, glycerol, dimethylformamide (DMF), N-methylpirrolidone (NMP), dimethylsulfoxide (DMSO), etc.) Pyridine derivatives which are finally substituted with alkyl or alkoxy groups and aryl groups substituted with halogen atoms are mixed with the main chain, 4-alkoxypicolinic acid, 4-alkyloxyalkoxypicolinic acid, 4-alkylaminepicolinic acid and 4-arylamine. Picolinic , 4-aminoalkylamine picolinic acid, 4-alkoxypicolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide, 4-alkylaminepicolinic acid-N-oxide, 4-arylamine Iridium complex compound ((5)) for solution process in which picolinic acid-N-oxide and 4-aminoalkylamine picolinic acid-N-oxide are introduced into the secondary ligand can be synthesized. The iridium complex showed a peak emission peak from approximately 450 nm- to 470 nm, confirming that it had pure blue emission properties.

Meanwhile, FIG. 1B is a reaction diagram schematically illustrating a process of synthesizing the iridium complex compound of Formula 1 according to an embodiment of the present invention. As shown, first, an aromatic boronic acid ((7)) such as a pyridine derivative ((6)) derivative substituted with an alkyl or alkoxy group having 1 to 20 carbon atoms and a phenylboronic acid substituted with a halogen atom such as fluorine is K _2. Synthesis was performed under CO ₃ , Pd (PPh ₃ ) _4, and THF solvent to form an arylpyridine zuligand ((8)) by Suzuki synthesis. Subsequently, the arylpyridine ligand obtained is reacted with a halogen substance such as iodine to synthesize, for example, an arylpyridine ligand substituted with three halogens ((9)). Subsequently, an arylpyridine uriganide ((9)) substituted with three halogens was reacted with an N-alkylpyrrolidinone to synthesize an alkyl group substituted with a halogen and a zuguride ((10)) substituted with two halogens, respectively. The mixture of iridium chloride hydrate (IrCl ₃ · 3H ₂ O) can then be dissolved in a suitable solvent and mixed to synthesize a chloride-bridged dimer ((11)). Crosslinked dimer ((6)) to 4-chloropicolinic acid or 4-chloropicolinic acid-N-oxide, dibutylaminepicolinic acid, dibutylaminepicolinic acid-N-oxide, aminopropylaminepi Cholinic acid, aminopropylaminepicolinic acid-N-oxide co-ligand and a suitable solvent (2-ethoxyethanol, glycerol, dimethylformamide (DMF), N-methylpirrolidone (NMP), dimethylsulfoxide (DMSO), etc.) Pyridine derivatives substituted with alkoxy groups An aryl group substituted with a halogen atom is selected from the main chain, 4-alkoxy picolinic acid, 4-alkyloxyalkoxy picolinic acid, 4-alkylamine picolinic acid, 4-arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxypicolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide, 4-alkylaminepicolinic acid-N-oxide, 4-arylaminepicolinic acid-N-oxide, 4- The iridium complex compound ((12)) for solution process in which aminoalkylamine picolinic acid-N-oxide was introduce | transduced into an auxiliary ligand can be synthesize | combined.

The iridium complex for the solution process synthesized through the above-described method, together with the existing blue phosphorescent iridium complex and UV-visible, PL and EL spectra, has greatly improved the emission color and solubility, and is used as a dopant for the light emitting layer of the organic light emitting diode. By using a solution process instead of vacuum deposition to obtain a pure blue light emitting layer, an organic electroluminescent device to which the iridium complex compound for the solution process synthesized according to the present invention can be applied will be described.

2a schematically illustrates an organic light emitting display device 100 in a single layer to which the above-described iridium complex compound may be applied according to an aspect of the present invention. The single layer organic light emitting diode 100 has a structure in which the substrate 110, the first electrode 120, the light emitting layer 160, and the second electrode 190 are sequentially stacked. The substrate 110 may be made of a material such as, for example, glass or plastic.

On the other hand, the first electrode 120 and the second electrode 190, for example, as a portion (anode) and the cathode (cathode), respectively, the first electrode 120 is compared to the second electrode 190 Use materials with large work functions. In particular, in relation to the present invention, the first electrode 120 is an effective material for injecting a hole, which is a positive-charged carrier, and is a metal, a mixed metal, an alloy, a metal oxide, or a mixed metal oxide or a conductive polymer. Can be. Specifically, the first electrode 120 may be indium-tin oxide (ITO), fluorine doped tin oxide (FTO), ZnO-Ga ₂ O ₃ , or ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O ₃ Materials such as mixed metal oxides, conductive polymers such as polyaniline, polythiophene, and the like may be used, and according to a preferred embodiment, ITO.

In contrast, the second electrode 190 is a material effective for injecting electrons, which are negative-charged carriers, as gold, aluminum, copper, silver, or alloys thereof; Aluminum, indium, calcium, barium, magnesium and alloys thereof, such as calcium / aluminum alloys, magnesium / silver alloys, aluminum / lithium alloys, and the like; Or in some cases, may be selected from metals belonging to rare earths, lanthanides, actinides, preferably aluminum, or aluminum / calcium alloys.

On the other hand, in the light emitting layer 160 stacked between the first electrode 120 and the second electrode 190, the above-described iridium complex for a solution process synthesized according to the present invention is used as a dopant. In this regard, the light emitting layer 160 includes a host, which is a light emitting material, to increase luminous efficiency by suppressing energy loss processes such as color purity change and quenching. In particular, in the case of the solution process iridium complex synthesized according to the present invention shows almost pure red light emission, the host is selected so that the energy emitted from the host included in the light emitting layer 160 can be transferred to the iridium complex compound, which is a dopant. Can be. According to the present invention, the host included in the light emitting layer 160 may include both a host having a fluorescent characteristic and a host having a phosphorescent characteristic, but a host having a phosphorescent characteristic. By way of example, the host, which is a light emitting material in the red region, may be, for example, poly (phenylenevinylene), polyvinylene (poly (fluorene)), or polyparaphenylene (poly (para-). polymer materials such as phenylene, PPP), poly (alkyllythiophene), and poly (pyridine), PPy), distyrylbenzene (DSB) and distyrylbenzene derivatives ( PESB), distyrylarylene (DSA), distyrylarylene derivatives, 1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (1,2,3,4,5- cyclopentadiene derivatives such as pentaphenyl-1,3-cyclopentadiene, PPCP), DPVBi (4,4'-bis (2,2'-diphenyl vinyl) -1,1'-biphenyl), DPVBi derivatives, spiro- Material such as DPVBi.

In particular, hosts having phosphorescent properties that can be used in connection with the present invention include aryl amines, carbazoles, and spiros. Specifically, 4,4-N, N-dicarbazole-biphenyl (4,4-N, N-dicarbazole-biphenyl, CBP), N, N-dicarbazoyl-3,5-benzene (N, N- dicarbazoyl-3,5-benzene, mCP), poly (vinylcarbazole, PVK), polyfluorene, 4,4'-bis [9- (3,6biphenylcarbazolyl)]-1- 1,1'-biphenyl4,4'-bis [9- (3,6-biphenylcarbazolyl)]-1-1,1'-biphenyl, 9,10-bis [(2 ', 7' -t-butyl) -9 ', 9' '-spirobifluorenyl anthracene, tetrafluorene (tetrafluorene) and the like may be included, preferably CBP and mCP may be used.

According to a preferred embodiment, the light emitting layer 160 is stacked on top of the first electrode 120 at a thickness of approximately 5 to 200 nm, preferably 50 to 10 nm, wherein the iridium complex synthesized according to the present invention is a dopant. It is included in a concentration of 3 to 20% by weight, preferably 5 to 10% by weight with respect to the light emitting layer 1170. In this case, the above-described iridium complex compound synthesized according to the present invention may adopt a conventional solution process, for example, an inkjet printing method or a screen printing method, in the process of laminating the upper portion of the first electrode 120.

On the other hand, the iridium complex synthesized according to the present invention, as well as the organic light emitting device 100 of the single layer type described above, a multi-layer organic field provided with a separate layer for electron / hole transport between the light emitting layer and the electrode. 2B is a schematic cross-sectional view of an organic light emitting display device 200 having a multi-layer type to which an iridium complex compound synthesized according to the present invention can be applied. As shown, the organic light emitting display device 200 includes a substrate 210, a first electrode 220, a hole injection layer HIL 240, and a hole transporting layer HTL 250. A buffer layer 230, a light emitting layer 260, an electron transporting layer (ETL, 270), an electron injection layer (EIL, 280), and a second electrode 290 sequentially stacked. It has a form.

In the organic light emitting diode having a multilayer structure configured as described above, the buffer layer 230 stacked between the first electrode 220 and the light emitting layer 260 is disposed between the material used as the first electrode 220 and the light emitting layer 260. Function to improve the interfacial properties of or to supply holes to the light emitting layer 260 stably. The buffer layer 230 may be divided into a hole injection layer 240 functionally stacked on the upper surface of the first electrode 220, and a hole transport layer 250 stacked between the hole injection layer 240 and the light emitting layer 260. Can be.

In this case, the hole injection layer 240 constituting the buffer layer 230 not only improves the interfacial properties between the ITO used as the first electrode 220 and the organic material used as the hole transport layer 250 but also has a flat surface. It is applied on top of ITO which is not used to make the surface of ITO smooth. In particular, the hole injection layer 240 is a work function level of ITO and hole transport layer 250 to adjust the difference between the work function level of ITO and the HOMO level of the hole transport layer 250 that can be used as the first electrode 220 As a material having a median value of HOMO level of), a material having a particularly suitable conductivity is selected. As a material forming the hole injection layer 240 in relation to the present invention, copper phthlalocyanine (CuPc), N, N'-dinaphthyl-N, N'-phenyl- (1,1'-biphenyl) -4,4'- diamine, NPD), 4,4 ', 4' '-tris [methylphenyl (phenyl) amino] triphenyl amine (m-MTDATA), 4,4', 4 ''-tris [1-naphthyl (phenyl) amino] triphenyl amine (1-TNATA), 4,4 ', 4' '-tris [2-naphthyl (phenyl) amino] triphenyl amine (2-TNATA), 1,3,5-tris [N- (4-diphenylaminophenyl) phenylamino aromatic amines such as benzene (p-DPA-TDAB), and poly (3,4-ethylenedioxythiophene) -poly (styrnesulfonate) (PEDOT), which is a polythiophene derivative as a conductive polymer, can be used. Was used. For example, the hole injection layer 240 may be coated on the upper portion of the first electrode 220 to a thickness of 20 ~ 200Å.

Meanwhile, a hole transport layer 250 is formed on the hole injection layer 240 so as to stably supply the holes introduced through the hole injection layer 2140 to the light emitting layer 260. Holes may be smoothly transported and transmitted. The material of which the HOMO level of the hole transport layer 240 is higher than the HOMO level of the light emitting layer 260 is selected. As a material that may be used in the hole transport layer 250 in accordance with the present invention, N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'-diphenyl-4,4'- diamine (TPD), N, N'-bis (1-naphthyl) -N, N'-biphenyl- [1,1'-biphenyl] -4,4'-diamine (TPB), N, N'-di ( naphthalene-1-yl) -N, N'-diphenyl-benzidene (NPB), triphenylamine (TPA), bis [4- (N, N-diethylamino) -2-methylphenyl] (4-methylphenyl) methane (MPMP ), N, N, N ', N'-tetrakis (4-methylphenyl)-(1,1'-biphenyl) -4,4-diamine (TTB), N, N'-bis (4-methylphenyl) -N Low molecular hole transport materials such as, N'-bis (4-ethylphenyl)-[1,1 '-(3,3'-dimethyl) biphenyl] -4,4'-diamine (ETPD); Polymer hole transport materials such as polyvinylcarbazole, polyaniline, (phenylmenyl) polysilane, and the like can be used. For example, the hole transport layer 250 may be deposited on the hole injection layer 240 to a thickness of about 10 to 100 nm.

However, substantially each material used in the hole injection layer 240 and the hole transport layer 250 includes both functions rather than having any one function. That is, in the above, it should be noted that the material used as the hole injection layer 240 not only improves the hole transport or transport but also the material used as the hole transport layer 250 also improves the hole injection. something to do. In other words, in the above description, the materials used for the hole injection layer 240 and the hole transport layer 250 can be distinguished, but such materials are only a matter of choice, and these materials are used as the first electrode 220 as a whole. ) And the buffer layer 230 between the light emitting layer 260.

Meanwhile, according to the present invention, the electron injection layer 280 and the electron transport layer 270 that may correspond to the above-described hole injection layer 240 and the hole transport layer 250 between the emission layer 260 and the second electrode 290. ) Is formed. The electron injection layer 280 is intended to induce smooth electron injection. Unlike other charge transfer layers, an alkali metal or alkaline earth metal ion form is used, such as LiF, BaF ₂ , CsF, and the like. And may be capable of inducing doping for 270.

On the other hand, the electron transport layer 270 is mainly composed of a material containing a chemical component that attracts electrons, for which high electron mobility is required, and stably supplies electrons to the light emitting layer 260 through smooth electron transport. In this case, particularly strong electron-receiver components can quench electrons, so it is preferable to use an appropriate electron-receiving component to improve electron mobility. Electron transport layer 270 that may be used in accordance with the present invention includes Alq ₃ and oxadizole components. Specifically, Tris (8-hydroxyquinolinato) aluminum (Alq ₃ ); 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA); 2- (4-biphenyl) -5- (4-tert-butyl) -1,3,4-oxadizole (PBD), 3- (4-biphenyl) -4-phenyl-5- (4-tert-butyl) Azole compounds such as -1,2,4-triazole (TAZ); phenylquinozaline and the like. For example, the electron transport layer 270 may be stacked on the emission layer 260 to a thickness of about 5 to 150 nm.

On the other hand, although not shown in the drawings, the life of the device when the holes introduced through the hole injection layer 240 and the hole transport layer 250 passes through the light emitting layer 260 to the second electrode 290 Since the efficiency may be reduced, a hole blocking layer (HBL) having a very low HOMO level may be formed between the emission layer 260 and the electron transport layer 270. Materials that can be used in the hole blocking layer in the present invention include 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), the light emitting layer 260 to a thickness of approximately 5 ~ 150 nm It may be deposited on top of).

As described above, the solution process iridium complex synthesized according to the present invention exhibits a wavelength corresponding to the pure blue region, and the improved solution process iridium complex is, as shown in FIG. 3, singlet and triplet. It was confirmed that not only the charge transfer state between the center metal-ligand of the term occurred but also light emission in the blue region of about 470 nm, as can be seen from the electrical characteristics of FIG. 4.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples.

Example 1 Preparation of 2- (2,4-Difluorophenyl) -4-methylpyridine Jurigan

In a 250 mL three-necked flask, 2-bromo-4-methylpyridine (6.88 g, 40 mmol, (2) in FIG. 1A) and 2,4-difluorophenylboronic acid (6.95 g, 44 mmol, (1) in FIG. 1A) Put it in. A reflux apparatus is placed in the flask containing the reagent and the solvent is added under nitrogen. THF (150 mL) purified by sodium / benzophenone is used as a solvent, and an additional 4 M aqueous potassium carbonate solution (10 mL) and ethanol (4 mL) are added thereto. Here potassium carbonate acts as a base during the reaction. Then remove the gas from the flask containing the mixture with liquid nitrogen and add additional tetrakis (triphenylphosphine palladium) (2.3 g, 2 mmol) as reaction catalyst under nitrogen. The reaction mixture was refluxed at 85 ° C. for 15 hours. After completion of the reaction, the mixture was cooled to room temperature. The organic layer was extracted with diethyl ether (2 × 200 mL) and brine. Water remaining in the organic layer extracted with anhydrous magnesium sulfate (MgSO ₄ ) is removed, and the magnesium sulfate containing water is filtered, and then the solvent is removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; hexane / ethyl acetate = 4: 1, v / v) to give a liquid 2- (2,4-difluorophenyl) -4-methylpyridine [(2- (2 , 4-Difluoro-3-trifluoromethyphenyl) -4-methylpyridine)] ((3) of FIG. 1A) can be obtained.

Yield: 83.6% (6.86 g)

^One H-NMR (CDCl ₃ , δppm): 8.55 (d, 1H), 7.94 (m, 1H), 7.57 (s, 1H), 7.08 (d, 1H), 7.01 (t, 1H), 6.98 (m, 2H), 2.42 (s, 3H)

Example 2. Preparation of chloride-bridged dimer

In a 100 mL flask, IrCl ₃ · 3H ₂ O (1.48 g, 4.2 mmol) and 2- (2,4-difluorophenyl) -4-methylpyridine (2.56 g, 12.5 mmol). To this was added 2-ethoxyethanol (30 mL) and water (10 mL) in a 3: 1 ratio, added as a solvent, and the mixture was refluxed at 130 ° C for 24 hours. It can be seen that the product is in a solid state during the reaction and is cooled to room temperature when the reaction is completed. The product is then filtered, washed with ethanol and dried in vacuo. The dried solid is a chlorine-crosslinked dimer which is yellow and intermediate of the final product ((4) of FIG. 1A).

Yield: 49.6% (3.16 g)

Elemental Analysis: Calcd. for (C ₄₈ H ₃₂ Cl ₂ F ₈ Ir ₂ N ₄ ): C, 45.32; H, 2.54; N, 4.40. Found: C, 46.12; H, 2. 44; N, 4.46.

Example 3 Preparation of Complex Compound Having Ethyloxyethoxy Picolinic Acid as Secondary Ligand

50 mL of the chlorine-crosslinked dimer obtained in Example 2 (1.02 g, 0.8 mmol), 4-chloropicolinic acid (0.33 g, 2.4 mmol), a secondary ligand precursor, and Na ₂ CO ₃ (0.82 g, 8 mmol) Put 2-ethoxyethanol (20 mL) into the volumetric flask and reflux at 130 ℃ for 15 ~ 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue is separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v) to obtain an iridium complex in which picolinic acid-N-oxide is introduced as a secondary ligand. The iridium complex obtained through this example is abbreviated as "(dfpmpy) ₂ Ir (EO-pic)".

Yield: 73% (0.43 g)

^One H-NMR (CDCl ₃ , δppm): 8.55 (d, 1H), 8.32 (d, 1H), 8.08 (d, 2H), 7.93 (t, 1H), 7.77 (d, 1H), 7.41 (t, 1H), 7.24 (d, 1H), 7.01 (d, 1H), 6.79 (d, 1H), 6.51-6.32 (m, 2H), 5.84 (d, 1H), 5.59 (d, 1H), 2.59 (s, 6H)

Example 4 Preparation of Complex Compound Having Ethyloxyethoxy Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 2 (1.02 g, 0.8 mmol) and 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8 mmol) as a secondary ligand precursor. ) Is added to a 50 mL volumetric flask and 2-ethoxyethanol (20 mL) is added as a solvent, and the mixture is refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v) and an iridium complex having ethyloxyethoxypicolinic acid-N-oxide introduced as a secondary ligand (FIG. 1A (5)). Get) The iridium complex obtained through this example is abbreviated as "(dFpmpy) ₂ Ir (EO-picN-O)".

Yield: 74% (0.49 g)

^One H-NMR (CDCl ₃ , δppm): 8.52 (d, 1H), 8.08 (s, 1H), 8.02 (s, 1H), 7.82 (d, 1H), 7.48 (d, 1H), 7.28 (d, 1H), 6.98 (d, 1H), 6.90 (dd, 1H), 6.77 (d, 1H), 6.46-6.31 (m, 2H), 5.80 (dd, 1H), 5.60 (dd, 1H), 4.22 (dd, 2H), 3.79 (t , 2H), 3.56 (dd, 2H), 2.53 (s, 6H), 1.22 (t, 3H)

Example 5 Preparation of Complex Compound Having Dibutylamine Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 2 (1.02 g, 0.8 mmol), 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8 mmol) as auxiliary ligand precursor ) Is added to a 50 mL volumetric flask and dibutylamine (20 mL) is added as a solvent and refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v), and an iridium complex having 4-dibutylamine picolinic acid-N-oxide introduced as an auxiliary ligand (FIG. 1A (5) )) The iridium complex obtained through this example is abbreviated as "(dFpmpy) ₂ Ir (Bu ₂ N-picN-O)".

Yield: 70% (0.48 g)

^One H-NMR (CDCl ₃ , δppm): 8.86 (d, 1H), 8.57 (d, 2H), 7.61 (s, 1H), 7.44 (s, 2H), 7.12 (d, 1H), 6.8-6.88 (m, 6H), 3.49 ( t, 4H), 2.37 (s, 6H), 1.56 (m, 4H), 1.35 (m, 4H), 0.96 (t, 6H)

Example 6 Preparation of Complex Compound Having Aminopropylamine Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 2 (1.02 g, 0.8 mmol), 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8) as co-ligand precursor mmol) is added to a 50 mL volumetric flask, and 1,3-diaminopropane (20 mL) is added as a solvent and refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v) and an iridium complex into which 4-aminopropylamine picolinic acid-N-oxide was introduced as a secondary ligand (FIG. 1A (5). )) The iridium complex obtained through this example is abbreviated as "(dFpmpy) ₂ Ir (H ₂ N- (CH ₂ ) ₃ N-picN-O)".

Yield: 71% (0.5 g)

^One H-NMR (CDCl ₃ , δ ppm: 8.86 (d, 1H), 8.57 (d, 2H), 7.61 (s, 1H), 7.44 (s, 2H), 7.12 (d, 1H), 6.8-6.88 (m, 6H), 3.06 ( t, 4H), 2.65 (t, 4H), 2.37 (s, 6H), 2.0 (s, 4H), 1.52-1.55 (m, 8H)

Example 7. Preparation of 2- (2,4-difluoro-3-iodophenyl) -4-methylpyridine zuligand

Into a 250 mL three-necked flask was added 2- (2,4-difluorophenyl) -4-methylpyridine (6.65 g, 33.4 mmol, (8) in FIG. 1B) obtained in Example 1. Into a flask containing reagents, THF (60 mL) purified with sodium / benzophenone is added under nitrogen. Maintaining -78 ℃ using acetoner / dry ice, add lithium diisopropylamine (3.72 g, 36.8 mmol) in hexane / THF, and stirred for 1 hour. Then add additional iodine (9.34 g, 36.8 mmol) dissolved in THF (50 mL). The reaction mixture was stirred for 4 hours at -78 ° C. After completion of the reaction by TLC, the mixture was returned to room temperature, and the organic layer was extracted using diethyl ether (2 x 200 mL) and brine. The separated organic layer was washed with distilled water (100 mL) and Na ₂ S ₂ O ₃ aqueous solution (100 mL), magnesium sulfate (MgSO ₄ ) was added thereto, dried, filtered and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; hexane / ethyl acetate = 4: 1, v / v) to give a liquid 2- (2,4-difluorophenyl-3-iodophenyl) -4-methylpyridine. [(2- (2,4-Difluoro-3-iodophenyl) -4-methylpyridine)] ((9) of FIG. 1B) can be obtained.

Yield: 76% (8.43 g)

^One H-NMR (CDCl ₃ , δppm): 8.57 (d, 1H), 7.95 (m, 1H), 7.57 (s, 1H), 7.12 (d, 1H), 7.03 (m, 1H), 2.42 (s, 3H)

Example 8 Preparation of 2- (2,4-Difluoro-3-trifluoromethylphenyl) -4-methylpyridine zuligand

Into a 100 mL flask, add copper (I) iodide (12.09 g, 63.5 mmol) and anhydrous potassium fluoride (2.21 g, 38.1 mmol) and heat under reduced pressure until it turns yellow. Nitrogen was sufficiently flowed into the reaction vessel, and 2- (2,4-difluoro-3-iodophenyl) -4-methylpyridine (8.43 g, 25.4 mmol) synthesized in Example 6 was added thereto, followed by N-methylpyrrolidinone. Add (24.4 mL) and (trifluoromethyl) trimethysilane (7.85 mL). The reaction mixture was stirred at room temperature for 24 hours, and after completion of reaction by TLC, 14% aqueous ammonia solution (100 mL) was added to the mixture, and the organic layer was extracted using dichloromethane (2 × 200 mL). The separated organic layer was washed with distilled water (100 mL) and brine (50 mL), and then added with magnesium sulfate (MgSO ₄ ), dried, filtered and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; hexane / ethyl acetate = 4: 1, v / v) to give a liquid 2- (2,4-difluoro-3-trifluoromethylphenyl) -4-methylpyridine. [(2- (2,4-Difluoro-3- trifluoromethyphenyl) -4-methylpyridine)] ((10) of FIG. 1B) can be obtained.

Yield: 49% (3.41 g)

^One H-NMR (CDCl ₃ , δppm): 8.59 (d, 1H), 7.98 (m, 1H), 7.60 (s, 1H), 7.17 (d, 1H), 7.04 (m, 1H), 2.46 (s, 3H)

Example 9 Preparation of chloride-bridged dimer

(Phenyl by 2,4 deployment in a _{triple-3) IrCl 3 · 3H 2 O (} 1.48 g, 4.2 mmol) as in one weeks ligand 2 prepared in Example 7 in the flask of 100 mL capacity 4 Methylpyridine (3.41 g, 12.5 mmol) is added. To this was added 2-ethoxyethanol (30 mL) and water (10 mL) in a 3: 1 ratio, added as a solvent, and the mixture was refluxed at 130 ° C for 24 hours. It can be seen that the product is in a solid state during the reaction and is cooled to room temperature when the reaction is completed. The product is then filtered, washed with ethanol and dried in vacuo. The dried solid is a chlorine-crosslinked dimer (11 in FIG. 1B) which is yellow and intermediate of the final product.

Yield: 52% (3.39 g)

Elemental Analysis: Calcd. for (C ₅₂ H ₂₈ Cl ₂ F ₂₀ Ir ₂ N ₄ ): C, 40.45; H, 1.83; N, 3.63. Found: C, 41.12; H, 1.72; N, 3.68.

Example 10 Preparation of Complex Compound Having Ethyloxyethoxy Picolinic Acid as Secondary Ligand

The chlorine-crosslinked dimer obtained in Example 9 (1.22 g, 0.8 mmol), 4-chloropicolinic acid (0.33 g, 2.4 mmol), a coligand auxiliary ligand precursor, and Na ₂ CO ₃ (0.82 g, 8 mmol) Into a 50 mL volumetric flask, 2-ethoxyethanol (20 mL) was added as a solvent and refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue is separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v) to obtain an iridium complex (12) of FIG. 1B into which picolinic acid-N-oxide is introduced as a secondary ligand. The iridium complex obtained through this example is abbreviated as "(dFCF ₃ pmpy) ₂ Ir (EO-pic)".

Yield: 74% (0.45 g)

^One H-NMR (CDCl ₃ , δppm): 8.57 (d, 1H), 8.35 (d, 1H), 8.16 (d, 2H), 7.76 (d, 1H), 7.49 (t, 1H), 7.11 (d, 1H), 6.90 (d, 1H), 5.96 (d, 1H), 2.59 (s, 6H)

Example 11 Preparation of Complex Compound Having Ethyloxyethoxy Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 9 (1.22 g, 0.8 mmol), 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8 mmol) as auxiliary ligand precursor ) Is added to a 50 mL volumetric flask and 2-ethoxyethanol (20 mL) is added as a solvent, and the mixture is refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v) and an iridium complex having ethyloxyethoxypicolinic acid-N-oxide introduced as a secondary ligand (FIG. 1B (12)). Get) The iridium complex obtained through this example is abbreviated as "(dFCF ₃ pmpy) ₂ Ir (EO-picN-O)".

Yield: 73% (0.49 g)

^One H-NMR (CDCl ₃ , δppm): 8.52 (d, 1H), 8.08 (s, 1H), 8.02 (s, 1H), 7.82 (d, 1H), 7.48 (d, 1H), 7.28 (d, 1H), 6.98 (d, 1H), 6.90 (dd, 1H), 6.43-6.31 (m, 1H), 5.80 (dd, 1H), 5.60 (dd, 1H), 4.22 (dd, 2H), 3.79 (t, 2H), 3.56 (dd , 2H), 2.53 (s, 6H), 1.22 (t, 3H)

Example 12 Preparation of Complex Compound Having Dibutylamine Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 9 (1.02 g, 0.8 mmol), 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8 mmol) as a secondary ligand precursor ) Is added to a 50 mL volumetric flask and dibutylamine (20 mL) is added as a solvent and refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v), and an iridium complex having 4-dibutylamine picolinic acid-N-oxide introduced as an auxiliary ligand (Fig. )) The iridium complex obtained through this example is abbreviated as "(dFCF ₃ pmpy) ₂ Ir (Bu ₂ N-picN-O)".

Yield: 68% (0.54 g)

^One H-NMR (CDCl ₃ , δppm): 9.5 (d, 1H), 8.7 (s, 1H), 8.57 (d, 2H), 8.2 (d, 1H), 7.44 (s, 2H), 6.88 (d, 2H), 6.8 (d, 2H), 3.49 (t, 4H), 2.37 (s, 6H), 1.56 (m, 4H), 1.35 (m, 2H), 0.96 (t, 6H)

Example 13. Preparation of Complex Compound Having Aminopropylamine Picolinic Acid-N-Oxide as Secondary Ligand

Chlorine-crosslinked dimer obtained in Example 9 (1.02 g, 0.8 mmol), 4-chloropicolinic acid-N-oxide (0.42 g, 2.4 mmol) and Na ₂ CO ₃ (0.82 g, 8 mmol) as a secondary ligand precursor ) Is added to a 50 mL volumetric flask and 1,3-diaminopropane (20 mL) is added as a solvent and refluxed at 130 ° C. for 15 to 17 hours. After completion of the reaction by TLC, the mixture was cooled to room temperature, the solvent was removed under reduced pressure, and the organic layer was extracted with dichloromethane (2 × 50 mL) and brine. The separated organic layer was dried over anhydrous magnesium sulfate (MgSO ₄ ), filtered, and the solvent was removed under reduced pressure. The obtained residue was separated by flash column chromatography (eluent; dichloromethane / methanol = 50: 1, v / v), and an iridium complex having 4-aminopropylamine picolinic acid-N-oxide introduced as an auxiliary ligand (Fig. )) The iridium complex obtained through this example is abbreviated as "(dFCF ₃ pmpy) ₂ Ir (H ₂ N- (CH ₂ ) ₃ N-picN-O)".

Yield: 70% (0.53 g)

^One H-NMR (CDCl ₃ , δppm): 9.5 (d, 1H), 8.7 (s, 1H), 8.57 (d, 2H), 8.2 (d, 1H), 8.06 (s, 1H), 7.44 (s, 2H), 6.8-6.88 ( m, 4H), 3.06 (t, 2H), 2.65 (t, 2H), 2.37 (s, 6H), 2.0 (s, 2H), 1.78 (m, 2H)

Example 14 Measurement of Absorption Spectrum of Iridium Complex

In the present embodiment, Shimadzu is prepared in the state of dissolving (dfpmpy) ₂ Ir (EO-picN-O) light emitting material, which is an iridium complex for solution processing, in which the soluble substituent synthesized through the process of Example 4 is introduced into the secondary ligand. UV-visible absorption spectra were measured using a UV-3100 spectrometer.

FIG. 3 is a graph showing UV-visible absorption spectrum measurement results for these light emitting materials in the state of using the iridium complex compound (dfpmpy) ₂ Ir (EO-picN-O) synthesized in Example 4 as a light emitting material. Looking at the UV absorption peak of the iridium complex synthesized according to the present invention, the transition phenomenon of the pyridine and phenyl derivative occurs at a wavelength of about 260 nm, the charge transfer between the central metal and the ligand of the singlet and triplet at a wavelength of about 380 ~ 480 nm It can be seen that the condition occurs. That is, the blue iridium complex (dfpmpy) ₂ Ir (EO-picN-O) synthesized for the solution process shows an absorption spectrum with better spectral characteristics than the conventional blue iridium complex.

Example 15. Fabrication of phosphorescent organic electroluminescent device

The iridium complexes (dfpmpy) ₂ Ir (EO-picN-O) and (dFCF ₃ pmpy) ₂ Ir (EO-picN-O), which are the iridium complexes synthesized through the processes of Examples 4 and 12, respectively, were prepared. An organic electroluminescent device used as a dopant for a light emitting layer was fabricated. In order to fabricate the organic light emitting device, first, the transparent electrode substrate coated with indium-tin oxide (ITO) on the glass substrate is thoroughly cleaned, and then the transparent electrode substrate coated with the ITO is coated with a photoresist resin and an etching solution ( etchant) was used to form the anode using a micromachining process and then washed again.

The hole injection layer was coated with poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonate) (PEDOT), a polythiophene derivative, which is a conductive polymer, and then baked at 110 ° C. for about 50 minutes. As the hole transport layer, NPB was vacuum deposited to a thickness of about 50 nm. In order to form the light emitting layer, CBP or mCP, which is widely used as a host material of a phosphorescent light emitting layer, is used as a host material of the light emitting layer, and the iridium complex of Example 4 (dfpmpy) ₂ Ir (EO-picN-O) And (dFCF ₃ pmpy) ₂ Ir (EO-picN-O) of Example 11 were used as dopants for the light emitting layer, and the concentration of the dopant was about 5-10%. The light emitting layer was formed by a vapor deposition method.

BCP and Alq ₃ were vacuum deposited to a thickness of 20-60 nm as the hole blocking layer and the electron transporting layer, respectively. The thin film was sequentially formed by vacuum deposition of LiF, which is an electron injection layer, to form an Al electrode, which is a cathode, to fabricate an organic light emitting display device. The vacuum degree for vacuum deposition was deposited while maintaining the 4x10 ^-6 torr or less to form a thin film. During deposition, the film thickness and growth rate were controlled by using a crystal sensor. The emission area was 4 ㎜ and the driving voltage was a direct bias voltage.

Example 16 Measurement of Electro-optical Properties of Organic Electroluminescent Light Emitting Diodes

Through Example 4 and Example 11, the iridium complex compounds (dfpmpy) ₂ Ir (EO-picN-O) and (dFCF ₃ pmpy) ₂ Ir (EO-picN-O) according to the present invention were respectively used as dopants of the light emitting layer. Electro-optic characteristics of the organic light emitting diodes used were measured. The current density and luminance of the organic light emitting diode fabricated according to Example 14 according to the increase in voltage were measured using Keithley 236 Source Measurement and Minolta LS-100. (dfCF ₃ pmpy) _{2 The} EL intensity of the phosphorescent organic electroluminescent device using Ir (EO-picN-O) as a dopant was measured. It can be seen that the device exhibits a maximum emission peak at about 456 nm, which is the same as the maximum emission peak in PL, thereby greatly improving the blue emission characteristics.

On the other hand, EL intensity measurement results of phosphorescent organic light emitting devices using (dfpmpy) ₂ Ir (EO-picN-O) as a dopant of the light emitting layer also showed a maximum emission peak at about 470 nm similar to the PL maximum emission peak. It can be seen that the blue light emission property is greatly improved.

Comparative Example: Measurement of physical properties of blue light-emitting phosphorescent organic electroluminescent device manufactured using Flrpic as a dopant

In this embodiment, organic electroluminescence using Flrpic (Iridium (III) bis [2-2 ', 4'-difluorophenyl) -pyridinato-N, C2'] picolinate, disclosed in US Pat. No. 6,835,469, is used as a dopant for the light emitting layer. EL intensity was measured for the device, and the measurement result is shown in FIG. 5. As shown, Flrpic, reported as a phosphorescent compound of conventional blue emission, exhibited a maximum emission peak at about 475 nm. It was confirmed that the blue light emission characteristics and efficiency were inferior to the iridium complex compound synthesized according to the present invention.

In the above, the present invention has been described in detail based on the preferred embodiments of the present invention, but the present invention is not limited thereto. Rather, those skilled in the art will be able to easily make various modifications and changes based on the embodiments described above. However, it will be more apparent through the appended claims that such variations and modifications fall within the scope of the present invention.

1A to 1B illustrate an aryl derivative substituted with a halogen atom and a pyridine derivative introduced with an alkyl or alkoxy substituent, respectively, according to an embodiment of the present invention, introduced into the main ligand, 4-alkoxypicolinic acid, 4-alkyloxyalkoxypicoli Nickel acid, 4-alkylamine picolinic acid, 4-arylamine picolinic acid, 4-aminoalkylamine picolinic acid, 4-alkoxy picolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide The mechanism by which iridium complexes into which 4-alkylaminepicolinic acid-N-oxide, 4-arylaminepicolinic acid-N-oxide and 4-aminoalkylaminepicolinic acid-N-oxide are introduced as auxiliary ligands is prepared. It is a schematic reaction diagram.

2A and 2B are cross-sectional views schematically showing organic light emitting diodes having a single layer type and a multi layer type, to which a iridium complex for a solution process synthesized according to the present invention is applied.

Figure 3 is a graph showing the results of measuring the UV-visible absorption spectrum using the iridium complex compound (dfpmpy) ₂ Ir (EO-picN-O) synthesized in accordance with an embodiment of the present invention in the light emitting layer.

Figure 4 is a graph showing the results of measuring the intensity of the photoluminescent (Photoluminescent, PL) of the iridium complex (dfpmpy) ₂ Ir (EO-picN-O) synthesized in accordance with an embodiment of the present invention.

FIG. 5 is a graph showing electroluminescence (EL) intensity measurement results for an electroluminescent device using Flrpic, an iridium complex compound known to exhibit blue light, as a dopant of a light emitting layer.

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

100, 200: light emitting element 110, 210: substrate

120, 220: first electrode 230: buffer layer

240: hole injection layer 250: hole transport layer

160, 260: light emitting layer 270: electron transport layer

280: electron injection layer 190, 290: second electrode

Claims (14)

Iridium complex compound represented by the following formula (1). Formula 1

(Formula 1 R ₁ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms; Ar is a phenyl group; R ₂ is halogen; R ₃ is hydrogen or an unsubstituted or substituted alkyl group having 1 to 20 carbon atoms;

Is 4-alkoxy picolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide, 4-alkylamine picolinic acid-N substituted with an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms -Oxide, 4-aminoalkylaminepicolinic acid-N-oxide.) The method of claim 1, R ₁ of Formula 1 is an iridium complex, characterized in that the alkyl group having 1 to 10 carbon atoms. The method of claim 1, Of Formula 1

Is 4-alkoxy picolinic acid-N-oxide, 4-alkyloxyalkoxypicolinic acid-N-oxide, 4-alkylamine picolinic acid-N substituted with an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms Iridium complex selected from -oxides, 4-aminoalkylaminepicolinic acid-N-oxides. The method of claim 1, R ₃ of Formula 1 is an iridium complex, characterized in that the alkyl group having 1 to 10 carbon atoms substituted by halogen. The method of claim 1, R ₂ of Formula 1 is an iridium complex, characterized in that fluorine or chlorine. An organic electroluminescent device in which the iridium complex compound according to any one of claims 1 to 5 is contained in a light emitting layer. The method of claim 6, The organic light emitting diode includes a first electrode and a second electrode formed to face the first electrode, and the light emitting layer is stacked between the first electrode and the second electrode. device. The method of claim 7, wherein An organic electroluminescent device further comprising a buffer layer between the first electrode and the light emitting layer, and an electron transfer layer and an electron injection layer between the light emitting layer and the second electrode. The method of claim 8, The buffer layer may include a hole injection layer stacked on top of the first electrode, and a hole transport layer stacked on top of the hole injection layer. The method of claim 6, The iridium complex compound is an organic electroluminescent device, characterized in that included as a dopant of the light emitting layer. The method of claim 6, The iridium complex compound is an organic light emitting device, characterized in that contained in a concentration of 3 to 20% by weight based on the total amount of the light emitting layer. A method of manufacturing an organic light emitting display device, the method comprising: laminating a light emitting layer containing an iridium complex compound according to any one of claims 1 to 5 on an upper portion of a first electrode. The method of claim 12, The light emitting layer is a method of manufacturing an organic light emitting display device, characterized in that stacked on top of the first electrode by a solution process. The method of claim 13, The light emitting layer is a method of manufacturing an organic light emitting display device, characterized in that stacked on top of the first electrode with a thickness of 5 ~ 200nm.

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