KR20150101865A - Phosphorescent iridium compound containing carboranes and oled devices using the same - Google Patents

Abstract

The present invention relates to a phosphorescent compound and a phosphorescent organic light-emitting device using the same and, more specifically, to a phosphorescent compound having carborane induced therein and substituted as a functional group at a predetermined position of a heteroleptic complex compound having iridum (Ir) as a central metal element, and to a phosphorescent organic light-emitting device using the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a phosphorescent compound containing carboranes and a phosphorescent organic light emitting device using the phosphorescent compound.

The present invention relates to a phosphorescent compound and a phosphorescent organic electroluminescent device using the phosphorescent compound, and more particularly, to a phosphorescent organic electroluminescent device using iridium (Ir) as a central metal element, And a phosphorescent organic light emitting device using the same.

However, as the demand for lightweight, low power consumption, portable, and flattening has increased, interest in flat panel displays has increased, and LCD (Liquid Crystal Display) Currently, organic light emitting diodes (OLEDs) are attracting attention as next-generation flat panel displays. OLED is a display capable of realizing characters and images of various colors by emitting a self-luminous organic substance when voltage is applied to a thin film made of an organic material (polymer or low molecule). It is a self-emitting type, ultra thin type ), Fast response speed (1000 times of LCD), low power consumption (1/2 of LCD), high definition and flexibility, it is attracting attention as a display for smart phones, tablets, notebooks, and wall-hanging TVs.

OLEDs have a structure in which a plurality of organic layers are laminated between a cathode and an anode as a principle of emitting visible light by recombination of holes and electrons. In general, glass is used as a substrate for OLED device manufacture, but sometimes a flexible plastic or film is applied. Indium-tin-oxide (ITO), which is formed by vacuum deposition or sputtering, is mainly used as the anode on the substrate. Vacuum deposition is used for the low molecular weight compound, spin coating is used for the high molecular weight compound, To form a thin film. The cathode requires magnesium or lithium having a small work function, but aluminum is mainly used in consideration of stability with respect to moisture and oxygen in the atmosphere.

A simple structure of the OLED has a sandwich structure in which an organic material having semiconductor characteristics exists between a cathode and an anode in the form of a thin film. When a DC electric field is applied to the two electrodes, electrons and holes are formed into organic materials Emitting layer to emit light in a visible light region. Generally, in order to improve the luminous efficiency of an OLED, various kinds of organic materials are formed in multiple layers between a cathode and an anode. For example, a hole injection layer (HIL) is formed on the anode electrode, and then a hole transporting layer (HTL), an emissive layer (EML), an electron transporting layer (ETL) , An electron injection layer (EIL), and a cathode electrode are sequentially formed. In the case of a light emitting layer, a host material and a dopant material are generally used, and doping with a very small amount of dopant can greatly improve light emitting efficiency.

In general, a vacuum deposition method using a fine metal mask is used as an OLED patterning technique. However, such a vacuum deposition method has a limitation in that it can not be applied to a large display due to its high process price and technical limitations. Accordingly, a variety of patterning techniques that can replace the vacuum evaporation method have been developed. In particular, a wet process such as a spin coating, an ink jet printing, a casting process and the like does not require a vacuum technique, It is easy to manufacture and is attracting attention in large display industry.

However, when the organic thin film layer is formed by a wet process, there is a problem that the material of the lower film already formed is dissolved by the organic solvent. Because of this problem, it is difficult to stack the organic thin film layer in multiple layers. There is a problem that can not be implemented.

In order to solve the above problems, a polymer material is mainly used as a wet process material. These polymeric materials are formed in a conjugated form in which aromatic substituents such as aryl groups and arylamine groups are extended covalently. Generally, as the molecular length increases, the conjugation length also increases. In this case, the energy bandgap of the molecule is consequently reduced. Since polymer materials having different energy band gaps are synthesized according to degree of polymerization even when the same monomer is used, polymer materials having various molecular weight distributions are synthesized even in a single reactor, and therefore, a polymer material having a specific energy band gap It is very difficult to obtain a thin film layer.

Therefore, in order to provide an organic light emitting device having excellent lifetime and efficiency characteristics by using a wet process which is easy to fabricate a device and has more advantages in terms of cost and size, the interface stability between the organic thin film layers is excellent and the energy band gap It is necessary to develop a new polymer which can be easily controlled.

On the other hand, phosphorescent organic light emitting diodes (PhOLED) based on heavy metal complexes are attracting interest because they can theoretically achieve 100% internal quantum efficiency by using both singlet and triplet excitons (JAG 2007, 281, 205-268., L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura and F. Barigelletti, Top. Curr. Chem., 2007, 281, 143 -20).

To prevent triplet-triplet extinction and condensation termination, the PHOLED typically comprises an active layer, wherein the phosphorescent compound is doped into a suitable host material.

In general, the host material of the PhOLED must have a higher triplet energy level (ET) than the phosphorescent compound for efficient energy transfer from the host to the guest and confinement of the triplet excitation of the guest material.

Conventional carbazole derivative-based low molecular weight host materials have been studied (V. Cleave, G. Yahioglu, P. Le Barny, RH Friend and N. Tessler, Adv. Mater., 1999, 11, 285-288; The polymer host material can also be used for the preparation of their solutions (see, for example, K. Brunner, A. van Dijken, H. Borner, JJAM Bastiaansen, NMM Kiggen and BMW Langeveld, J. Am. Chem. Soc., 2004, 126, 6035-6042) Which is the subject of interest.

However, unlike the light emitting layer in the low molecular weight PhOLED device, the light emitting layer of the PhOLED device manufactured by mixing the polymer host and the phosphorescent compound easily causes the phase separation, that is, the integration of the phosphorescent compound, have.

In order to overcome this problem, various techniques for preparing a PhOLED device in which a host material and a phosphorescent iridium (III) complex are inserted into a single copolymer, such as an iridium complex covalently bonded conjugated copolymer, Many studies have been reported on copolymers in which the complexes and host materials are attached to the side chain of the polymer backbone conjugated as pendant moieties. Prior art documents related thereto include Korean Patent Laid-Open Publication No. 2006-0098860, Korean Patent Laid-Open Publication No. 2008-0080765, Korean Patent Laid-Open Publication No. 2012-0140034, Korean Patent Laid-open Publication No. 2013-0070507, have.

However, the performance of the conjugated or residue copolymer based phosphorescent organic light emitting device is lower than that of general vacuum deposition devices.

In order to improve the efficiency of the phosphorescent organic light emitting device, it is required that the high triplet energy of the host molecule and the excellent charge transporting property, as well as the high electrical properties such as the high photoluminescence property of the iridium complex containing the phosphorescent iridium complex as the low molecular weight host and pendant residues, It is required to be designed to be combined with the processability of the skeleton. Accordingly, there is a growing demand for new phosphorescent compounds applicable to phosphorescent organic light emitting devices having high efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a phosphorescent compound capable of realizing high color purity, high efficiency and long life characteristics as dopants dopable in a light emitting layer of a phosphorescent organic light emitting device, Emitting organic electroluminescent device.

In order to achieve the above object, one aspect of the present invention provides a phosphorescent compound represented by the following general formula (1).

≪ Formula 1 >

가

,

, 또는

이며, 상기 작용기(R)가 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기이다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

end

,

, or

Wherein said functional group (R) is selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, Methylphenyl, and biphenyl.

(오르소-, ortho-),

(메타-, meta-), 및

(파라-, para-)로 이루어진 군으로부터 선택되는 하나일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).

(오르소-, ortho-)일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-).

In one embodiment, the functional group (R) may be a methyl group.

According to another aspect of the present invention, there is provided a phosphorescent compound represented by the following general formula (2).

(2)

가

,

, 또는

이며, 상기 작용기(R)가 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기이다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

end

,

, or

Wherein the functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Lt; / RTI > is a single functional group selected from the group consisting of fluoromethylphenyl, fluoromethylphenyl, and biphenyl.

(오르소-, ortho-),

(메타-, meta-), 및

(파라-, para-)로 이루어진 군으로부터 선택되는 하나일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).

(오르소-, ortho-)일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-).

In one embodiment, the functional group (R) may be a methyl group.

According to another aspect of the present invention, there is provided a phosphorescent compound represented by Formula 3 below.

(3)

이

또는

이며, 상기

가

,

, 또는

이고, 상기 작용기(R)가 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기이다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

this

or

, And

end

,

, or

Wherein said functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Lt; / RTI > is a single functional group selected from the group consisting of fluoromethylphenyl, fluoromethylphenyl, and biphenyl.

(오르소-, ortho-),

(메타-, meta-), 및

(파라-, para-)로 이루어진 군으로부터 선택되는 하나일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).

(오르소-, ortho-)일 수 있다.In one embodiment, the functional (R) substituted carbene group is

(Ortho-).

In one embodiment, the functional group (R) may be a methyl group or an n-butyl group.

In one embodiment, the phosphorescent compound may be represented by the following general formula (4) or (5).

≪ Formula 4 >

≪ Formula 5 >

가

,

, 또는

이고, 상기 R이 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기이다.In the above formula,

end

,

, or

Wherein R is a group selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t- butyl, n- pentyl, neopentyl, n-hexyl, phenyl, tolyl, , And biphenyl.

In one embodiment, R may be a methyl or n-butyl group.

According to another aspect of the present invention, there is provided a phosphorescent organic electroluminescent device including a cathode, a cathode, and a light emitting layer between both electrodes, wherein the phosphorescent compound is a phosphorescent organic electroluminescent Device.

In one embodiment, the anode is a transparent electrode, and the cathode may be a metal electrode.

In one embodiment, a first charge transport layer may be further included between the anode and the light emitting layer.

In one embodiment, the first charge transport layer may include a hole injection layer and a hole transport layer.

In one embodiment, a second charge transport layer may be further included between the cathode and the light emitting layer.

In one embodiment, the second charge transport layer may include an electron transport layer and an electron injection layer.

In one embodiment, a hole blocking layer may be further disposed between the light emitting layer and the electron transporting layer.

In one embodiment, an electron blocking layer may be further disposed between the light emitting layer and the hole transporting layer.

According to an embodiment of the present invention, a phosphorescent compound in which carborane substituted with a functional group is introduced at a certain position of a heteroleptic complex having iridium (Ir) as a central metal element is applied to a light emitting layer of a phosphorescent organic light emitting device High color purity, high efficiency and long life characteristics of the phosphorescent organic light emitting device can be realized.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a cross-sectional view of a phosphorescent organic light emitting diode according to an embodiment of the present invention.
2 is a cross-sectional view of a phosphorescent organic light emitting diode according to another embodiment of the present invention.
3 is a cross-sectional view of a phosphorescent organic light-emitting device according to another embodiment of the present invention.
FIG. 4 is a diagram illustrating UV-vis absorption and photoluminescence (PL) spectra of a phosphorescent compound according to an embodiment of the present invention.
5 is a voltage-current diagram of a phosphorescent compound according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating UV-vis absorption and photoluminescence (PL) spectra of a phosphorescent compound according to another embodiment of the present invention.
7 is a voltage-current diagram of a phosphorescent compound according to another embodiment of the present invention.
8 is a schematic view of an electroluminescence spectrum of a phosphorescent organic light emitting diode according to an embodiment of the present invention.
9 is a diagram illustrating external quantum efficiency-luminance and power efficiency-luminance curve of a phosphorescent organic light emitting device according to an embodiment of the present invention.
10 is a graphical representation of an electroluminescence spectrum of a phosphorescent organic light emitting device according to another embodiment of the present invention.
11 is a diagram illustrating external quantum efficiency-luminance and power efficiency-luminance curve of a phosphorescent organic light emitting device according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Phosphorescent compound

One aspect of the present invention provides a phosphorescent compound represented by the following general formula (1).

≪ Formula 1 >

가

,

, 또는

이며, 상기 작용기(R)가 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기일 수 있고, 바람직하게는 메틸기일 수 있으나, 이에 한정되는 것은 아니다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

end

,

, or

Wherein said functional group (R) is selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, Methylphenyl, and biphenyl, and it may preferably be a methyl group, but is not limited thereto.

과

가 이리듐에 배위 결합된 고리 금속 이리듐 착화합물(cyclometalated complex)이다.The phosphorescent compound contains iridium (Ir) as a central metal element and ligand

and

Is a cyclometalated complex coordinated to iridium.

이 선택되고, 상기

리간드의 페닐기 중 4번 탄소 위치에 작용기(R) 치환된 오르소-카보레인기(ortho-carborane group, R-C₂B₁₀H₁₀)가 치환된 구조를 가진다.The phosphorescent compound represented by the general formula (1) is a ligand of the cyclic metal iridium complex

Is selected,

Carborane group (RC ₂ B ₁₀ H ₁₀ ) substituted with a functional group (R) at the 4-carbon position of the phenyl group of the ligand.

Since the iridium and ligand have a metal-carbon bond in the cyclic metal iridium complex, transition of the charge to the pyridine ring of the ligand (metal to ligand charge transfer, MLCT) is apt to occur. As described above, the MLCT transition is apt to occur, resulting in easy generation of phosphorescence as a forbidden transition, shortening the triplet excitation lifetime, and improving the luminous efficiency of the cyclic metal iridium complex.

리간드의 치환기를 다변화함으로써 달성될 수 있다.In addition, by partially modifying the cyclic metal iridium complex, the emission color over the entire visible light region can be controlled. Such correction or adjustment of the phosphorescence color

Can be achieved by diversifying the substituent of the ligand.

리간드의 구조를 변화시킴으로써 여기 상태(excited state) 에너지를 변화시킬 수 있다.Specifically, the above-mentioned effects on the energy levels of HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital)

The excited state energy can be changed by changing the structure of the ligand.

리간드에 있어서, 상기 고리 금속 이리듐 착화합물의 HOMO는 페닐 고리의 π 오비탈과 이리듐의 d_π 오비탈에 의해 조절될 수 있고, LUMO는 피리딜 고리의 π* 오비탈에 의해 조절될 수 있다. 결과적으로, 불소 원소와 같은 전자 당김기(electron withdrawing group)의 상기 리간드의 페닐 고리로의 도입은 HOMO 준위를 낮춤으로써 HOMO-LUMO 밴드 갭을 증가시키는 반면에, 상기 리간드의 피리딜 고리로의 도입은 LUMO 준위를 낮춤으로써 밴드 갭을 감소시킬 수 있다. 즉, HOMO-LUMO 전이로부터 형성되는 삼중항 상태의 에너지 준위는 밴드 갭을 변화시킴으로써 정밀하게 조절될 수 있다.For example,

In the ligand, the HOMO of the cyclic metal iridium complex can be controlled by the π orbitals of the phenyl ring and the d _π orbitals of iridium, and the LUMO can be controlled by the π * orbitals of the pyridyl ring. As a result, the introduction of an electron withdrawing group such as a fluorine element into the phenyl ring of the ligand increases the HOMO-LUMO band gap by lowering the HOMO level, while the introduction of the ligand into the pyridyl ring Can reduce the bandgap by lowering the LUMO level. That is, the energy level of the triplet state formed from the HOMO-LUMO transition can be precisely controlled by changing the bandgap.

On the other hand, the carborane group is a substance having specific physical properties, such as a high-polarity sigma -aromatic characteristic, an electron deficiency characteristic, and excellent heat and chemical stability, which is substituted at a specific position of the ligand, The luminescent efficiency of the metal iridium complex can be improved and the lifetime can be prolonged.

The carbene group not only directly contributes to the delocalization of LUMO but also can significantly lower the LUMO level due to the strong electron withdrawing effect. In addition, since the carborean group has a large molecular size, it can interfere with intermolecular interaction between phosphorescent light emitting molecules, thereby preventing triplet-triplet extinction and concentration termination in a solid state.

(오르소-, ortho-),

(메타-, meta-), 및

(파라-, para-)로 이루어진 군으로부터 선택되는 하나일 수 있고, 바람직하게는

(오르소-, ortho-)일 수 있다.The functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-), and preferably one selected from the group consisting of

(Ortho-).

리간드의 페닐 고리 중 4번 또는 5번 탄소 위치에 도입 또는 치환된 고리 금속 이리듐 착화합물은, 기타의 유기 화합물이 도입 또는 치환되지 않은 것에 비해 적색에서 청색 시프트까지 방출 파장이 용이하게 조정될 수 있다.
Particularly, when the ortho-carbene group is the

The ring metal iridium complex introduced or substituted at the carbon position 4 or 5 of the phenyl ring of the ligand can easily adjust the emission wavelength from red to blue shift as compared to the other organic compound is not introduced or substituted.

According to another aspect of the present invention, there is provided a phosphorescent compound represented by the following general formula (2).

(2)

가

,

, 또는

이며, 상기 작용기(R)가 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기일 수 있고, 바람직하게는 메틸기일 수 있으나, 이에 한정되는 것은 아니다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

end

,

, or

Wherein the functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Methylphenyl, fluoromethylphenyl, and biphenyl, preferably methyl, but is not limited thereto.

이 선택되고, 상기

리간드의 페닐기 중 5번 탄소 위치에 작용기(R) 치환된 오르소-카보레인기(ortho-carborane group, R-C₂B₁₀H₁₀)가 치환된 구조를 가진다.The phosphorescent compound represented by the general formula (2) is a ligand of the cyclic metal iridium complex

Is selected,

Carborane group (RC ₂ B ₁₀ H ₁₀ ) substituted with a functional group (R) at the carbon position 5 in the phenyl group of the ligand.

Regarding the improvement of the phosphorescent emission efficiency by the interaction of the central metal element, the ligand, the type of carboranes and the carbazole substitution of the functional group in the phosphorescent compound of the above formula (2) 1. ≪ / RTI >

가

이고, 상기

리간드의 페닐기 중 4번 또는 5번 탄소 위치에 작용기(R)가 치환되며, 상기 R이 메틸기인 인광 화합물은 하기 반응식 1에 의해 표시되는 경로에 따라 제조될 수 있다.In the phosphorescent compounds represented by the above Chemical Formulas 1 to 2,

end

, And

A phosphorescent compound in which the functional group (R) is substituted at the 4th or 5th carbon position of the phenyl group of the ligand and the R is a methyl group can be prepared according to the route represented by the following reaction formula (1).

[Reaction Scheme 1]

According to Reaction Scheme 1, the phosphorescent compound of Formula 1 to Formula 2 may be prepared by: (i) preparing a first ligand to which a methyl group-substituted carbene group is introduced; (ii) reacting the first ligand with iridium (III) chloride to produce a first cyclic metal iridium complex; And (iii) reacting the first cyclic metal iridium complex with a second ligand to produce a second cyclic iridium complex.

The step (i) is a step of preparing a first ligand of a heteroleptic cyclic metal iridium complex according to an embodiment. The first ligand may have a different structure depending on the position at which the carbene group is introduced in the starting material. When the starting material of the first ligand is 1- (4-bromophenyl) -2-methyl-1,2-chloro- carbonyl, the resulting cyclic metal iridium complex according to Formula 2 may be synthesized And when the starting material is 1- (3-bromophenyl) -2-methyl-1,2-chloro- carbonyl, the resulting cyclic metal iridium complex according to Formula 3 may be finally synthesized.

Hereinafter, (4-CBppy) ₂ Ir (acac) (CB: ortho-methylcarboranes (IV)) using 1- (4-bromophenyl) , ppy: 2-phenylpyridinato-C ² , N, acac: acetylacetonate) A method for preparing a phosphorescent compound of Formula 1 to Formula 2 will be described in detail, The method for producing the phosphorescent compound according to the present invention is not limited thereto, and may include known reactions, processes, and combinations thereof.

The step (i) is a step of preparing a first ligand of the cyclic metal iridium complex, specifically, 1- (4-bromophenyl) -2-methyl-1,2-chloro- 2- (trimethylstannyl) -pyridine is reacted in an organic solvent in the presence of a catalyst to give 2- {p- (2-methyl-2-methyl- (2-methyl-1, 2-carbazol-1-yl) phenyl} pyridine) .

The step (ii) is a step of coordinating the first ligand with iridium, which is a central metal element, to prepare a first cyclic metal iridium complex, specifically, the 2- {p- (2-methyl- (III) (IrCl ₃ ) was prepared by reacting an organic (2-methyl-1, 2-trifluoroethyl) [(4-CBppy) ₂ Ir (μ-Cl)] ₂ (or [(5-CBppy) ₂ Ir (μ-Cl)] ₂ ) is prepared by heating and stirring in a mixed solvent of a solvent and distilled water. .

The step (iii) comprises coordinating the second ligand with iridium, which is a central metal element, to prepare a second cyclic metal iridium complex, specifically, [(4-CBppy) ₂ Ir ₂ (or [(5-CBppy) ₂ Ir (μ-Cl)] ₂ ) and 2,4-pentanedione are reacted in an organic solvent in the presence of a catalyst to obtain a phosphorescent compound represented by Formula 1 (4-CBppy) ₂ Ir (acac) (or (5-CBppy) ₂ Ir (acac)) (acac: acetylacetonate).

According to another aspect of the present invention, there is provided a phosphorescent compound represented by the following general formula (3).

(3)

이

또는

이며, 상기

가

,

, 또는

이고, 상기 작용기(R)가 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기일 수 있고, 바람직하게는 메틸기 또는 n-부틸기일 수 있으나, 이에 한정되는 것은 아니다.Wherein the R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )

this

or

, And

end

,

, or

Wherein said functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Fluoromethylphenyl, and biphenyl, preferably methyl or n-butyl, but is not limited thereto.

The phosphorescent emission mechanism by the interaction of the central metal element, the ligand, and the carbazole-substituted carbazole in the phosphorescent compound of the above formula (3), and thus the improvement of the phosphorescence efficiency and the type of the carbobore popular Is the same as that described above with respect to Formula 1 above.

In one embodiment, the phosphorescent compound of Formula 3 may be represented by Formula 4 or Formula 5.

≪ Formula 4 >

≪ Formula 5 >

가

,

, 또는

이고, 상기 R이 수소, 메틸, 에틸, n-프로필, i-프로필, n-부틸, i-부틸, t-부틸, n-펜틸, 네오펜틸, n-헥실, 페닐, 톨릴, 트리플루오로메틸페닐, 및 바이페닐로 이루어진 군으로부터 선택되는 하나의 작용기일 수 있고, 바람직하게는 메틸기 또는 n-부틸기일 수 있으나, 이에 한정되는 것은 아니다.In the above formula,

end

,

, or

Wherein R is a group selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t- butyl, n- pentyl, neopentyl, n-hexyl, phenyl, tolyl, , And biphenyl, and may be preferably a methyl group or an n-butyl group, but is not limited thereto.

를 그대로 사용한 예는 공지된 바 있으며, 이 때의 착화합물이 적색의 고에너지 한계(620~700 nm)에 근접한 612 nm에서 인광 파장을 가지는 것으로 보고되었다. 일반적으로, 착화합물의 HOMO 준위를 상승시키거나 LUMO 준위를 하강시킴으로써 적색 발광체를 설계할 수 있다. 이 중, 전자의 방법은 상기 리간드의 페닐 고리에 전자 공여기를 도입시켜 달성될 수 있고, 후자의 방법은 상기 리간드의 피리딘 고리에 전자 당김기를 도입시켜 달성될 수 있다.As the ligand of the cyclic metal iridium complex

Has been known, and it has been reported that the complex at this time has a phosphorescence wavelength at 612 nm close to the high energy limit of red (620 to 700 nm). Generally, red phosphors can be designed by increasing the HOMO level of the complex or by lowering the LUMO level. Among them, the former method can be achieved by introducing an electron donor into the phenyl ring of the ligand, and the latter method can be achieved by introducing an electron withdrawing group into the pyridine ring of the ligand.

가 선택되고, 상기

리간드의 피리딘 고리 중 5번 탄소 위치에 작용기(R) 치환된 오르소-카보레인기(ortho-carborane group, R-C₂B₁₀H₁₀)가 치환된 구조를 가진다. 상기

리간드에 오르소 카보레인기가 도입되면,

만을 리간드로 사용하는 경우에 비해 깊은 적색 발광(644 nm)을 구현할 수 있다.The phosphorescent compound of formula (4) is a ligand of the cyclic metal iridium complex

Is selected,

Carborane group (RC ₂ B ₁₀ H ₁₀ ) substituted with a functional group (R) at the carbon position 5 of the pyridine ring of the ligand. remind

When an orthocarborane group is introduced into the ligand,

(644 nm) as compared with the case where only the ligand is used as the ligand.

가 선택되고, 상기

리간드의 2,4-디플루오로페닐기 중 3번 탄소 위치에 작용기(R) 치환된 오르소-카보레인기(ortho-carborane group, R-C₂B₁₀H₁₀)가 치환된 구조를 가진다.The phosphorescent compound of formula (5) is a ligand of the cyclic metal iridium complex

Is selected,

Carborane group (RC ₂ B ₁₀ H ₁₀ ) substituted with a functional group (R) at the 3-carbon position of the 2,4-difluorophenyl group of the ligand.

이고, 상기 R이 메틸기인 인광 화합물은 하기 반응식 2에 의해 표시되는 경로에 따라 제조될 수 있다.In the phosphorescent compound of Formula 4, end

And R is a methyl group, can be prepared according to the route represented by the following reaction formula (2).

[Reaction Scheme 2]

According to Reaction Scheme 2, the phosphorescent compound of Formula 4 may be prepared by (i) replacing the hydrogen end of 2-chloro-5-ethynylpyridine with a methyl or n-butyl group to give 2-chloro-5- -1-yl) pyridine or 2-chloro-5- (hex-1-yn-1-yl) pyridine; (ii) Synthesis of 2-chloro-5- (prop-1-yn-1-yl) pyridine or 2-chloro-5- (hex- -Benzo [b] thiophen-2-yl) -5- (prop-1-yn-1-yl) pyridine Or 2- (benzo [b] thiophen-2-yl) -5- (hex-1-yn-1-yl) pyridine; (iii) 2- (benzo [b] thiophen-2-yl) -5- (prop- - (hex-1-yn-1-yl) pyridine with decaborane (B ₁₀ H ₁₄ ) to produce a first ligand; (iv) reacting the first ligand with iridium (III) chloride to produce a first cyclic metal iridium complex; And (v) reacting the first cyclic metal iridium complex with a second ligand to produce a second cyclic iridium complex.

The above steps (i) to (iii) are the steps of preparing a first ligand of a heteroleptic cyclic metal iridium complex according to an embodiment. The first ligand may have a different structure depending on the kind of the functional group (R) substituted at the terminal of 2-chloro-5-ethynylpyridine as a raw material. If the functional group (R) is a methyl group, the first ligand is 5-MeCBbtpH (5-MeCBbtp: 2- (2'-benzothiazolyl) -5- (2-methyl-ortho-carbonyl- pyrido Dina sat -C ^2, N) may be, n- butyl group is 5-BuCBbtpH (5-BuCBbtp: 2- (2'- between benzo carbonyl) -5- (2-butyl-ortho-carborane -1-yl) -pyridinato-C ² , N).

(5-MeCBbtp) ₂ Ir (acac) (acac: acetylacetonate) cyclic metal iridium complex using 5-MeCBbtpH as a first ligand in the above reaction scheme 2, Although the method will be described in detail, the method for producing the phosphorescent compound according to the present invention is not limited thereto, and may include known reactions, processes, and combinations thereof.

The above steps (i) to (iii) are the steps of preparing a first ligand of the cyclic metal iridium complex, specifically, 2-chloro-5- (prop- Yl) pyridine and benzo [b] thiophene-2-yl-boronic acid in an organic solvent in the presence of a catalyst to form 2- (benzo [b] thiophene- (5-MeCBbtp: 2-yl) -5- (prop-1-yn-1-yl) pyridine was obtained by reacting dicarboranine (B ₁₀ H ₁₄ ) (2'-benzothienyl) -5- (2-methyl-ortho-carbonyl- 1-yl) -pyridinato-C ² , N).

The (iv) step is a step for preparing a first ring of metal iridium complex by coordination bond to the central metal element to the first ligand of iridium, specifically the 5-MeCBbtpH and iridium chloride (III) (IrCl ₃₎ (5-MeCBbtp) ₂ Ir (μ-Cl)] ₂ is prepared by heating and stirring in a mixed solvent in which an organic solvent and distilled water are mixed and heated in a mixed solvent in which an organic solvent and distilled water are mixed.

The step (v) comprises the step of coordinating the second ligand with iridium, which is a central metal element, to prepare a second ring metal iridium complex, specifically, [(5-MeCBbtp) ₂ Ir ₂ and 2,4-pentanedione are reacted in an organic solvent in the presence of a catalyst to prepare (5-MeCBbtp) ₂ Ir (acac) which is one of the phosphorescent compounds represented by the formula (4).

Phosphorescent organic light emitting element

In another aspect of the present invention, there is provided a phosphorescent organic light emitting device including a cathode, a cathode, and a light emitting layer between both electrodes, wherein the phosphorescent compound of Chemical Formulas 1 to 5 is used as a dopant material, -emitting diodes (OLEDs).

The anode may be a transparent electrode, and the cathode may be a metal electrode. For example, the transparent electrode may be formed of indium tin oxide (ITO) or SnO ₂ , and the metal electrode may be formed of a metal such as Li, Mg, Ca, Ag, Al, In, In particular, the metal electrode may have a single layer or a multilayer structure of two or more layers.

The light emitting layer may include a phosphorescent compound of the general formulas (1) to (5) as a dopant material, and may have a single layer or a multilayer structure of two or more layers. A host material can be used together with a phosphorescent dopant in the light emitting layer, and a low molecular weight or high molecular weight host can be used. Examples of the low molecular weight host include 9,9 '- (1,1'-biphenyl) -4,4'-diyl bis-9H-carbazole (CBP) and 9,9' (PNB CBP), polynorbornene-mCP (PNB mCP), and poly- (N-vinylcarbazole) (PVCz CBP) ): PBD (or OXD-7).

Generally, a multilayered device in which a light emitting layer and a charge transport layer are combined, exhibits excellent device characteristics, rather than a single-layered device composed of only a single light emitting layer. This is because an appropriate combination of a light emitting material and a charge transporting material, The barrier is reduced, and the charge transport layer confines the holes or electrons injected from the electrodes to the light emitting layer region, so that the number density of injected holes and electrons is balanced. In particular, in the case of a phosphorescent organic light emitting device, since the emission duration of the phosphorescent compound is long, holes are confined in the light emitting layer to stay in the light emitting layer for a long time in order to increase the efficiency.

1 and 2, the phosphorescent organic light emitting diode 100 includes an anode (transparent electrode) 110, a first charge transport layer 120, a light emitting layer 130, a second charge transport layer 140, (Metal electrode) 150 may be sequentially stacked. The light emitting layer 130 may include a phosphorescent compound of the above Chemical Formulas 1 to 5 as a dopant material. The first charge transporting layer 120 and the second charge transporting layer 140 are formed of a hole injection layer 121 and a hole transporting layer 122 and an electron transporting layer 141 and an electron injection layer 142, Can be separated.

The hole injection layer 121 may be inserted into a conventional hole injection layer including, for example, copper phthalocyanine (CuPc), and the electron injection layer 142 may include, for example, LiF And may be inserted into a conventional electron injecting layer.

The hole transport layer 122 may be formed using conventional hole transport materials such as 4,4-bis [N- (1-naphthyl) -N-phenylamine] biphenyl (N-NPD) Diphenyl-N, N-bis (3-methylphenyl) -1,1-biphenyl-4,4-diamine (TPD) and poly- (N-vinylcarbazole) (PVCz) And may have a multilayer structure in which two or more layers are stacked as required.

The electron transporting layer (electron transporting light emitting layer) 141 may be a conventional electron transporting material such as tris (8-quinolinolato) aluminum (Alq3), 4,7-diphenyl-1,10-phenanthroline (Bphen) Or rubrene may be used singly or in combination of two or more, and may have a multilayer structure in which two or more layers are stacked as required.

3, the phosphorescent organic light emitting diode 100 includes an electron blocking layer 170 between the light emitting layer 130 and the hole transporting layer 122, and a light emitting layer 130 and the electron transporting layer 141 The hole blocking layer 160 may be formed on the hole blocking layer 160.

As the electron blocking layer 170, a material having a large LUMO value is generally used, and iridium (III) tris (1-phenylpyrazole-N, C2 ') (Ir (ppz) ₃ ) is suitable. Also, the hole blocking layer 160 has a lowest unoccupied molecular orbital (LUMO) value between 5.5 and 7.0, and has a hole transporting ability remarkably deteriorated, and a material having an excellent electron transporting ability, for example, 1,3,5-tris (BCP), 3- (4-biphenylyl) -4-phenyl-5- (4-t-butoxycarbonyl) -Butylphenyl) -1,2,4-triazole (TAZ), bis (8-hydroxy-2-methylquinolinato) -aluminum biphenoxide (BAlq) and the like.

The anode, the cathode, the light emitting layer, the transport layer, the injection layer, and the barrier layer may be formed by a conventional deposition method. Since the phosphorescent compound of Formula 1 to Formula 5 is included as a dopant in the phosphorescent organic light emitting device and exhibits stable luminescence and exhibits excellent external quantum efficiency and power efficiency, And can be usefully used in light emitting devices (PhOLEDs).

Hereinafter, embodiments of the present invention will be described in detail. However, these examples are intended to further illustrate the present invention, and the scope of the present invention is not limited to these examples.

Example  1: phosphorescent compound 1, (4- CBppy ) ₂ Ir ( acac )

(i) Step: The first ligand of  Produce

(1.48 g, 5.57 mmol), 2- (trimethylstannyl) -pyridine (1.48 g, 6.13 mmol), and Pd (PPh ₃ ) ₄ (Tetrakis (triphenylphosphine) palladium) (0.13 g, 2.0 mol%) in toluene (70 mL) was heated and refluxed for 1 day. After cooling to room temperature, the reaction mixture was quenched by adding saturated aqueous NH ₄ Cl solution. The organic phase was separated and the aqueous layer was further extracted with Et ₂ O (30 mL). Dry the combined organic layers with MgSO ₄ and concentrated under reduced pressure. The residue was purified by flash column chromatography using CH ₂ Cl ₂ / toluene (1/1, v / v) as the eluent. After vacuum drying, 2- {p- (2-methyl-1,2-carbonyl-1-yl) phenyl} pyridine as a white solid was obtained (Yield: 1.03 g, yield: 54%).

_{^{1 H NMR (CDCl 3):}} δ 8.70 (dq, 1H, J = 4.8, 0.9 Hz), 7.99 (dt, 2H, J = 8.7, 2.1 Hz), 7.70-7.80 (m, 4H), 7.27 (ddd, 1H, J = 6.9, 4.8, 1.5 Hz), 1.70 (s, 3H, B-CH 3), 1.50-3.70 (br, 10H, BH). _{^{13 C NMR (CDCl 3):}} δ 155.7, 149.9, 141.5, 137.1, 131.5, 131.3, 127.3, 123.0, 120.8 (ppy-C), 81.8, 77.4 (C 2 B 10 H 10), 23.2 (B-CH 3 ). _{^{11 B NMR (CDCl 3):}} -3.0, -4.4, -10.0. HR EI-MS (C ₁₄ H ₂₁ B ₁₀ N): m / z 313.2605 (calculated); 313.2606 (experimental value).

( ii ) Step: Preparation of first ring metal iridium complex

Phenyl) pyridine (1.03 g, 3.29 mmol) and IrCl ₃ .3H ₂ O (0.51 g, 1.43 mmol) were added to a solution of 2- {p- (2-methyl-1,2- Was dissolved in a mixed solvent of ethoxyethanol (40 mL) and distilled water (20 mL), and the mixture was heated to 110 DEG C and stirred for one day. After cooling to room temperature, 30 mL of distilled water was added to precipitate a solid material. The precipitate was filtered and washed with a small amount of ethanol (2 x 10 mL). The crude solid was extracted with CH ₂ Cl ₂ and the solution was dried with MgSO ₄ . Filtered and vacuum dried to obtain [(4-CBppy) ₂ Ir (μ-Cl)] ₂ (CB: ortho-methylcarboranes, ppy: 2-phenylpyridinato-C ² , N) in a yellow solid state . (Yield: 1.07 g, yield: 88%).

_{^{1 H NMR (CDCl 3):}} δ 9.31 (d, 4H, J = 5.7 Hz), 7.92 (m, 8H), 7.44 (d, 4H, J = 8.4 Hz), 7.01 (m, 8H), 6.01 (d , 4H, J = 1.8 Hz) , 1.33 (s, 12H, B-CH 3), 1.20-3.50 (br, 40H, BH). _{^{13 C NMR (CDCl 3):}} δ 167.1, 151.7, 145.9, 144.1, 137.4, 132.7, 130.6, 124.4, 123.4, 123.2, 120.0, 82.0, 71.5 (C 2 B 10 H 10), 22.9 (B-CH 3) . _{^{11 B NMR (CDCl 3):}} δ -4.3, -9.5. Analysis (C ₅₆ H ₈₀ B ₄₀ Cl ₂ Ir ₂ N ₄ ): C, 39.63; H, 4.75; N, 3.30 (calculated). C, 39.63; H, 4.81; N, 3.27 (experimental value).

( iii ) Step: Preparation of phosphorescent compound 1, (4- CBppy ) ₂ Ir ( acac )

_{[(4-CBppy) 2 Ir} (μ-Cl)] 2 (CB: ortho-methyl-carborane, ppy: 2- phenylpyridinato Dina sat ^{-C 2, N) (1.03 g} , 0.63 mmol), 2,4 -Pentanedione (0.19 g, 1.90 mmol), Na ₂ CO ₃ (0.67 g, 6.32 mmol) and acetonitrile (50 mL) were placed in a flask and heated to 80 ° C. and stirred for 2 days. After cooling to room temperature, the orange precipitate formed was collected by filtration and washed with acetonitrile (10 mL). The undissolved solid was extracted with CH ₂ Cl ₂ to remove residual salts. The solution was dried with MgSO ₄ and filtered. The solvent was evaporated and vacuum dried to obtain (4-CBppy) ₂ Ir (acac) (CB: ortho-methylcarboranes, ppy: 2-phenylpyridinato-C ² , N, acac: Nate). (Yield: 0.95 g, yield: 83%). The acetone / methanol solution of (4-CBppy) ₂ Ir (acac) was slowly evaporated to obtain a single crystal suitable for the X-ray diffraction test.

_{^{1 H NMR (CDCl 3):}} δ 8.50 (d, 2H, J = 6.0 Hz), 7.87 (m, 4H), 7.42 (d, 2H, J = 8.4 Hz), 7.30 (td, 2H, J = 6.0, 2H, J = 2.1 Hz), 5.31 (s, 1H, acac-CH), 1.83 (s, 6H, acac-CH3 ), 1.14 (s, 6H, B-CH 3), 1.10-3.00 (br, 20H, BH). ^{_{13 C NMR (CD 2 Cl 2}} ): δ 185.7 (acac-CO), 167.2, 149.2, 147.9, 147.8, 138.5, 135.0, 130.4, 124.5, 123.8, 123.6, 120.0, 101.2 (acac-CH), 83.2, 77.9 (C ₂ B ₁₀ H ₁₀ ), 28.8 (acac-CH ₃ ), 22.9 (B-CH ₃ ). _{^{11 B NMR (CDCl 3):}} δ -4.8 (br, 4B), -10.4 (br, 6B). Analysis (C ₃₃ H ₄₇ B ₂₀ IrN ₂ O ₂ ): C, 43.45; H, 5.19; N, 3.07 (calculated). C, 43.38; H, 5.19; N, 3.08 (experimental value).

Example  2: phosphorescent compound 2, (5- CBppy ) ₂ Ir ( acac )

(i) Step: The first ligand of  Produce

(1.79 g, 5.72 mmol), 2- (trimethylstannyl) -pyridine (1.66 g, 6.87 mmol), and Pd _{(PPh 3) 4 (Tetrakis (} triphenylphosphine) palladium) (0.13 g, 2.0 mol%) in the same manner as the step (i) of example 1, except for using 2- {m- (2- methyl-1 , 2-carbonyl-1-yl) phenyl} pyridine. (Yield: 1.24 g, yield: 70%).

_{^{1 H NMR (CDCl 3):}} δ 8.71 (dq, 1H, J = 4.8, 1.8 Hz), 8.30 (t, 1H, J = 1.8 Hz), 8.03 (dt, 1H, J = 7.8, 1.2 Hz), 7.81 (td, 1H, J = 7.8,1.8 Hz), 7.70 (tt, 2H, J = 7.8,1.2 Hz), 7.48 (t, 1H, J = 7.8 Hz), 7.27 Hz), 1.72 (s, 3H , B-CH 3), 1.50-3.70 (br, 10H, BH). _{^{13 C NMR (CDCl 3):}} δ 156.1, 150.2, 140.5, 137.2, 131.7, 131.5, 130.0, 129.5, 129.1, 123.0, 120.9 (ppy-C), 82.3, 77.5 (C 2 B 10 H 10), 23.5 ( B-CH _{3). ^{11 B NMR (CDCl 3):}} δ -3.0, -4.5, -10.0. HR EI-MS (C ₁₄ H ₂₁ B ₁₀ N): m / z 313.2605 (calculated); 313.2605 (experimental value).

step ( ii ): Preparation of first cyclic metal iridium complex

Except that the above 2- {m- (2-methyl-1,2-carbonyl-1-yl) phenyl} pyridine (1.24 g, 3.99 mmol) and IrCl ₃ .3H ₂ O (0.61 g, 1.73 mmol) [(5-CBppy) ₂ Ir (μ-Cl)] ₂ (CB: ortho-methylcarboline, ppy: 2-phenylpyridinato-C ² , N). (Yield: 1.46 g, yield: 93%).

_{^{1 H NMR (CDCl 3):}} δ 9.08 (d, 4H, J = 5.7 Hz), 7.88 (m, 8H), 7.69 (s, 4H), 6.88 (t, 4H, J = 6.6 Hz), 6.79 (d , 4H, J = 8.1 Hz) , 5.90 (d, 4H, J = 8.1 Hz), 1.53 (s, 12H, B-CH 3), 1.20-3.50 (br, 40H, BH). ^{13 C NMR (acetone-d6)} : δ 167.9, 153.1, 151.2, 147.1, 139.8, 132.5, 132.4, 127.3, 125.9, 125.4, 121.5, 85.5, 79.7 (C 2 B 10 H 10), 22.9 (B-CH 3 ). _{^{11 B NMR (CDCl 3):}} δ -4.4, -10.1. Analysis (C ₅₆ H ₈₀ B ₄₀ Cl ₂ Ir ₂ N ₄ ): C, 39.63; H, 4.75; N, 3.30 (calculated). C, 39.38; H, 4.37; N, 3.09 (experimental value).

step ( iii ): Phosphor compound 2, (5- CBppy ) ₂ Ir ( acac )

_{[(5-CBppy) 2 Ir} (μ-Cl)] 2 (1.37 g, 0.81 mmol), 2,4- pentanedione (0.24 g, 2.43 mmol), and _{Na 2 CO 3 (0.86 g,} 8.09 mmol) to (5-CBppy) ₂ Ir (acac) (CB: ortho-methylcarboline, ppy: 2-phenylpyridinato-C ² , N , acac: acetylacetonate). (Yield: 1.40 g, yield: 95%).

_{^{1 H NMR (CDCl 3):}} δ 8.48 (d, 2H, J = 5.4 Hz), 7.92 (d, 2H, J = 8.1 Hz), 7.83 (dt, 2H, J = 8.4, 1.5 Hz), 7.71 (d 2H, J = 2.1 Hz), 7.23 (m, 2H), 6.87 (dd, 2H, J = 8.1, 2.1 Hz), 6.22 CH), 1.79 (s, 6H , acac-CH 3), 1.57 (s, 6H, B-CH 3), 1.10-3.10 (br, 20H, BH). ^{_{13 C NMR (CD 2 Cl 2}} ): δ 185.4 (acac-CO), 167.0, 152.5, 148.7, 146.5, 138.1, 134.0, 131.2, 126.2, 123.7, 123.2, 119.4, 100.9 (acac-CH), 84.1, 78.1 (C ₂ B ₁₀ H ₁₀ ), 28.5 (acac-CH ₃ ), 23.3 (B-CH ₃ ). _{^{11 B NMR (CDCl 3):}} δ -4.5 (br, 4B), -10.1 (br, 6B). Analysis (C ₃₃ H ₄₇ B ₂₀ IrN ₂ O ₂ ): C, 43.45; H, 5.19; N, 3.07 (calculated). C, 43.56; H, 5.21; N, 3.06 (experimental value).

Example  3: phosphorescent compound 3, (5- MeCBbtp ) ₂ Ir ( acac )

(i): introduction of functional group (R)

2-Chloro-5-ethynylpyridine, which is the raw material of step (i), and 2-chloro-5- (hex-1-yn-1-yl) pyridine in which the hydrogen terminal thereof is substituted with n- (Haponachchige, S .; Montano, G .; Ramesh, C .; Rodriguez, D .; Henson, LH; Williams, CC; Kadavakkollu, S.; Johnson, DL; Shuster, CB; Arterburn, JBJ Chem. Soc, 2011, 133, 6780-6790, Arterburn, JB; Corona, C .; Rao, KV; Carlson, KE; Katzenellenbogen, JAJ Org. Chem., 2003, 68, 7063-7070).

Meanwhile, a tetrahydrofuran solution of 2-chloro-5-ethynylpyridine (0.80 g, 5.8 mmol) was treated with lithium diisopropylamide (3.2 mL, 6.4 mmol) at 0 ° C. and stirred for 1 hour. (3 eq, 2.5 g, 17.5 mmol) in MeI (methyl iodide) was added to the mixture. The reaction mixture was slowly warmed to room temperature and stirred for 2 hours. The reaction mixture was quenched with water (30 mL) and the aqueous layer was extracted with ether. The organic layer was filtered and dried with MgSO _4, and concentrated under reduced pressure. Purification by silica column chromatography using n-hexane / CH ₂ Cl ₂ (2: 1) as an eluent gave 2-chloro-5- (prop-1-yn-1-yl) pyridine. (Yield: 0.72 g, yield: 82%).

_{^{1 H NMR (CDCl 3):}} δ 8.27 (dd, J = 5.1, 0.5 Hz, 1H), 7.26 (s, 1H), 7.13 (dd, J = 5.1, 1.4 Hz, 1H), 2.05 (s, 3H) . ¹³ C NMR (CDCl ₃ ): δ 151.53, 149.38, 135.14, 126.17, 124.40, 93.20, 76.54, 4.47. Analysis (C ₈ H ₆ ClN): C, 63.38; H, 3.99; N, 9.24 (calculated). C, 63.60; H, 4.07; N, 9.12 (experimental value).

( ii ) step : Benzo [b] thiophene group  Introduction

(0.72 g, 4.7 mmol), benzo [b] thiophen-2-yl-boronic acid (0.93 g, 4.7 mmol) in tetrahydrofuran to a mixture of, 5.2 mmol), and _{Pd (PPh 3) 4 (0.11} g, 0.10 mmol) Na 2 CO 3 Aqueous solution (1.5 g, 14.2 mmol, 10 mL). The mixture was stirred at 80 < 0 > C for 24 hours. After cooling to room temperature, water (20 mL) was added, the organic layer was separated, and the aqueous layer was extracted with CH ₂ Cl ₂ (30 mL). The combined organic layers were dried over MgSO ₄ , filtered, concentrated under reduced pressure and the yellow residue was purified by column chromatography using n-hexane / CH ₂ Cl ₂ (3: 1) as eluent to give (Benzo [b] thiophen-2-yl) -5- (prop-1-yn-1-yl) pyridine as a white solid. (Yield: 0.80 g, yield: 68%).

_{^{1 H NMR (CDCl 3):}} δ 8.61 (t, J = 1.4 Hz, 1H), 7.86-7.82 (m, 1H), 7.80-7.75 (m, 2H), 7.68 (t, J = 1.3 Hz, 2H) , 7.34-7.30 (m, 2H), 2.08 (s, 3H). ¹³ C NMR (CDCl ₃ ): δ 152.14, 150.67, 144.30, 140.78, 140.42, 138.89, 125.14, 124.55, 124.14, 122.55, 121.43, 119.87, 118.75, 90.41, 76.74, 4.52. Analysis (C ₁₆ H ₁₁ NS): C, 77.07; H, 4.45; N, 5.62 (calculated). C, 77.12; H, 4.46; N, 5.55 (experimental value).

( iii ) Step: The first ligand of  Produce

(B ₁₀ H ₁₄ , 0.43 g, 3.52 mmol) and 2- (benzo [b] thiophen-2-yl) -5- (prop- 1 -yl- 1 -yl) pyridine Et ₂ S (2.5 eq., 0.95 mL, 8.86 mmol with respect to B ₁₀ H ₁₄ ) was added to a toluene solution (100 mL) of the compound Lt; / RTI > Solvent was removed under vacuum and methanol (50 mL) was administered. The resulting red solid was filtered off and redissolved in toluene. The solution was filtered through an alumina column and the solvent was removed in vacuo to afford a white solid. Recrystallization from a mixed solvent of acetone and methanol gave 5-MeCBbtpH (5-MeCBbtp: 2- (2'-benzothiazolyl) -5- (2-methyl-ortho-carbonyl- Dinato-C ² , N). (Yield: 0.74 g, yield: 63%).

_{^{1 H NMR (CDCl 3):}} δ 8.86 (d, J = 2.2 Hz, 1H), 7.94 (dd, J = 8.6, 2.4 Hz, 1H), 7.89-7.86 (m, 2H), 7.83-7.81 (m, 1H), 7.78 (d, J = 8.6 Hz, 1H), 7.39-7.36 (m, 2H), 3.20-1.60 (br, 10H, CB-BH), 1.74 (s, _{^{13 C NMR (CDCl 3):}} δ 154.25, 151.39, 142.83, 141.15, 140.20, 139.00, 125.79, 125.67, 124.82, 124.52, 123.01, 122.68, 118.88, 78.86 (CB-C), 77.12 (CB-C), 23.26 . _{^{11 B NMR (CDCl 3):}} δ -2.5, -4.3 (br s, 3B), -9.8 (br s, 7B). Analysis (C ₁₆ H ₂₁ B ₁₀ NS): C, 52.29; H, 5.76; N, 3.81 (calculated). C, 52.31; H, 5.76; N, 3.80 (experimental value).

( iv ) Step: Preparation of first ring metal iridium complex

5-MeCBbtpH (0.63 g, 1.71 mmol) and IrCl ₃ .3H ₂ O (0.23 g, 0.78 mmol) were dissolved in a mixed solvent of 2-ethoxyethanol (40 mL) and distilled water (20 mL). The reaction mixture was heated to 110 DEG C and stirred for one day. The reaction mixture was cooled to room temperature and 30 mL of distilled water was then added to precipitate the solid material. The precipitate was filtered off and washed with a small amount of ethanol (2 x 10 mL) and water (3 x 10 mL). And dried under vacuum to obtain [(5-MeCBbtp) ₂ Ir (μ-Cl)] ₂ in a red solid state. (Yield: 0.37 g, yield: 49%) Analysis result (C ₆₄ H ₈₀ B ₄₀ Cl ₂ Ir ₂ N ₄ S ₄ ): C, 40.01; H, 4.20; N, 2.92 (calculated). C, 39.66; H, 4.35; N, 2.97 (experimental value).

(v): Phosphor compound 3, (5- MeCBbtp ) ₂ Ir ( acac )

_{[(5-MeCBbtp) 2 Ir} (μ-Cl)] 2 (0.10 g, 0.052 mmol), 2,4- pentanedione (0.015 g, 0.15 mmol), and _{Na 2 CO 3 (0.055 g,} 0.52mmol) is Acetonitrile (15 mL) was added to the flask. The reaction mixture was heated to 80 DEG C and stirred for 2 days. After cooling to room temperature, the resulting yellow precipitate was collected by filtration and washed with acetonitrile (10 mL). Unrefined solids were extracted with CH ₂ Cl ₂ . The filtrate was evaporated under reduced pressure to obtain (5-MeCBbtp) ₂ Ir (acac) in a red solid state. A single crystal suitable for X-ray diffraction analysis was obtained by slow evaporation of the methanol solution of (5-MeCBbtp) ₂ Ir (acac). (Yield: 0.072 g, yield: 68%

_{^{1 H NMR (CDCl 3):}} δ 8.68 (d, J = 1.9 Hz, 2H), 7.96 (dd, J = 8.6, 2.4 Hz, 2H), 7.66 (d, J = 7.9 Hz, 2H), 7.60 (d J = 8.6 Hz, 2H), 7.10 (t, J = 7.3 Hz, 2H), 6.73 (t, J = 7.3 Hz, 2H), 6.18 ), 3.1-1.5 (br, 20H, CB-BH), 1.84 (s, 6H), 1.80 (s, 6H). _{^{13 C NMR (CDCl 3):}} δ 185.29, 167.43, 151.41, 150.77, 146.53, 143.23, 140.62, 134.33, 126.09, 125.71, 123.73, 123.12, 121.72, 117.55, 100.64, 78.83 (CB-C), 77.72 (CB- C), 28.16,23.24. _{^{11 B NMR (CDCl 3):}} δ -3.1 and -4.2 (br s, 5B), -9.9 (br s, 15B). Mp = 357 < 0 > C. Analysis (C ₃₇ H ₄₇ B ₂₀ IrN ₂ O ₂ S ₂ ): C, 43.38; H, 4.62; N, 2.73 (calculated). C, 43.69; H, 4.77; N, 2.71 (experimental value).

Example  4: phosphorescent compound 4, (5- BuCBbtp ) ₂ Ir ( acac )

(i): introduction of functional group (R)

2-Chloro-5- (hex-1-yn-1-yl) pyridine in which the hydrogen terminal of 2-chloro-5-ethynylpyridine is substituted with an n-butyl group was prepared by a known method (Hapuarachchige, S .; Sherman, CB, Arterburn, JBJ Am. Chem. Soc., 2011, 133, 6780, Johnson, R.; Ramesh, C .; Rodriguez, D .; Henson, LH; Williams, CC; Kadavakkollu, Arterburn, JB, Corona, C .; Rao, KV; Carlson, KE; Katzenellenbogen, JAJ Org. Chem., 2003, 68, 7063-7070).

( ii ) step : Benzo [b] thiophene group  Introduction

(1.1 g, 5.7 mmol), benzo [b] thiophen-2-yl-boronic acid (1.3 g, 7.3 mmol), Pd (PPh _{3) 4 (0.14 g, 0.12} mmol), and Na ₂ CO ₃ (Benzo [b] thiophen-2-yl) -5- (hexane-1-carboxylate) was obtained in the same manner as in step (ii) of Example 3, except that the aqueous solution (1.9 g, 17.9 mmol) -1-yn-1-yl) pyridine. (Yield: 1.40 g, Yield: 84%).

_{^{1 H NMR (CDCl 3):}} δ 8.60 (t, J = 1.5 Hz, 1H), 7.85-7.83 (m, 1H), 7.78-7.76 (m, 2H), 7.67 (d, J = 1.5 Hz, 2H) , 7.34-7.32 (m, 2H), 2.44 (t, J = 7.0 Hz, 2H), 1.63-1.57 (m, 2H), 1.51-1.45 ). ¹³ C NMR (CDCl ₃ ): δ 152.14, 150.57, 144.32, 140.75, 140.41, 138.89, 125.11, 124.53, 124.12, 122.56, 121.38, 119.93, 118.70, 95.01, 77.52, 30.62, 22.03, 19.26, Analysis (C ₁₉ H ₁₇ NS): C, 78.31; H, 5.88; N, 4.81 (calculated). C, 77.97; H, 5.84; N, 4.81 (experimental value).

( iii ) Step: The first ligand of  Produce

2- (benzo [b] between 2-yl) -5- (hex-1-yl) pyridine (1.25 g, 4.29 mmol), dicarboxylic borane _{(B 10 H 14, 0.63 g} , 5.15 5-BuCBbtpH (5-BuCBbtp: 2- (4-fluorobenzyl) -2,3-dioxolan-2-yl) was prepared in the same manner as in step (iii) of Example 3, except that Et ₂ S (2'-benzothienyl) -5- (2-butyl-ortho-carbonyl-1-yl) -pyridinato-C ² , N). (Yield: 0.95 g, yield: 54%).

_{^{1 H NMR (CDCl 3):}} δ 8.84 (d, J = 2.2 Hz, 1H), 7.92-7.86 (m, 3H), 7.83-7.81 (m, 1H), 7.76 (d, J = 8.0 Hz 1H), (M, 2H), 1.15-1.06 (m, 2H), 7.39-7.36 (m, 2H), 3.20-1.80 (br, , 0.75 (t, J = 7.5 Hz, 3 H). _{^{13 C NMR (CDCl 3):}} δ 154.19, 151.42, 142.82, 141.10, 140.17, 138.99, 125.77, 125.57, 124.80, 124.49, 123.02, 122.63, 118.82, 82.45 (CB-C), 80.28 (CB-C), 34.96 , 31.56, 22.08, 13.46. _{^{11 B NMR (CDCl 3):}} δ -3.4 (br s, 2B), -9.9 (br s, 8B). Analysis (C ₁₉ H ₂₇ B ₁₀ NS): C, 55.71; H, 6.64; N, 3.42 (calculated). C, 55.50; H, 6.65; N, 3.37 (experimental value).

( iv ) Step: Preparation of first ring metal iridium complex

5-BuCBbtpH (5-BuCBbtp: 2- (2'-benzothiazolyl) -5- (2-butyl-ortho-carbonyl-1-yl) -pyridinato-C ² , N) [(5-BuCBbtp) ₂ Ir (μ-Cl)] ₂ was obtained in the same manner as in the above (iv) of Example 3.

(v): Phosphor compound 4, (5- BuCBbtp ) ₂ Ir ( acac )

_{[(5-BuCBbtp) 2 Ir} (μ-Cl)] 2 (0.060 g, 0.029 mmol), 2,4- pentanedione (0.009 g, 0.09 mmol), and _{Na 2 CO 3 (0.031 g,} 0.29 mmol) to (5-BuCBbtp) ₂ Ir (acac) was obtained in the same manner as in the step (v) of Example 3 except that (Yield: 0.043 g, yield: 67%).

_{^{1 H NMR (CDCl 3):}} δ 8.63 (d, J = 1.8 Hz, 2H), 7.93 (dd, J = 8.7, 2.0 Hz, 2H), 7.66 (d, J = 8.1 Hz, 2H), 7.60 (d (D, J = 7.8 Hz, 2H), 5.32 (s, 1H, J = ), 3.2-1.6 (br, 20H, CBBH), 1.88-1.82 (m, 4H), 1.83 (s, 6H), 1.45-1.34 (m, 4H), 1.16-1.06 , ≪ / RTI > J = 7.2 Hz, 6H). _{^{13 C NMR (CDCl 3):}} δ 185.13, 167.37, 151.39, 150.79, 146.49, 143.14, 140.61, 134.26, 126.06, 125.63, 123.90, 123.09, 121.65, 117.52, 100.67, 82.67 (CB-C), 79.87 (CB- C), 35.08, 31.73, 28.19, 22.33, 13.66. _{^{11 B NMR (CDCl 3):}} δ -3.4 (br s, 5B), -9.9 (br s, 15B). Mp = 322 [deg.] C. Analysis (C ₄₃ H ₅₉ B ₂₀ IrN ₂ O ₂ S ₂ ): C, 46.59; H, 5.36; N, 2.53 (calculated). C, 46.33; H, 4.91; N, 2.32 (experimental value).

Comparative Example  1: Phosphor compound 5, (4- fppy ) ₂ Ir ( acac )

(6)

_{[(4-fppy) 2 Ir} (μ-Cl)] 2 (4-fppy: 2- ( 4-fluorophenyl) -pyrido Dina sat ^{-C 2, N) (0.176 g} , 0.154 mmol), 2,4 (5) was obtained in the same manner as in the above step (iii) of Example 1 or Example 2 except that pentanedione (0.039 g, 0.385 mmol) and Na ₂ CO ₃ (0.163 g, (4-fppy) ₂ Ir (acac) was obtained. (Yield: 0.122 g, yield: 62%).

^{_{1 H NMR (CD 2 Cl 2}} ): δ 8.43 (dt, 2H, J = 4.2 Hz), 7.80 (m, 4H), 7.59 (dd, 2H, J = 8.7, 5.7 Hz), 7.21 (dt, 2H, 2H, J = 6.0, 2.1 Hz), 6.58 (dt, 2H, J = 8.7, 2.7 Hz), 5.87 (dd, 2H, J = 9.9, 2.7 Hz), 5.30 (s, ^{_{13 C NMR (CD 2 Cl 2}} ): 185.5 (acac-CO), (acac-CH) 148.7, 138.1, 126.1, 126.0, 122.4, 119.6, 119.3, 119.2, 108.7, 108.4, 101.0, 28.8 (acac-CH3) . Analysis (C ₂₇ H ₂₁ F ₂ IrN ₂ O ₂ ): C, 51.01; H, 3.33; N, 4.41 (calculated). C, 50.99; H, 3.62; N, 4.21 (experimental value).

Comparative Example  2: phosphorescent compound 6, (4- BuCBbtp ) ₂ Ir ( acac )

≪ Formula 7 >

_{[(4-BuCBbtp) 2 Ir} (μ-Cl)] 2 (0.12 g, 0.057 mmol), 2,4- pentanedione (0.018 g, 0.17 mmol), and _{Na 2 CO 3 (0.060 g,} 0.57 mmol) to (4-BuCBbtp) ₂ Ir (acac) represented by the formula (6) was obtained in the same manner as in the step (v) of Example 3 or Example 4, (Yield: 0.092 g, yield: 72%).

_{^{1 H NMR (CDCl 3):}} δ 8.43 (d, J = 6.1, 2H), 7.71 (d, J = 1.6, 2H), 7.66 (d, J = 8.1 Hz, 2H), 7.17 (dd, J = 6.3 (D, J = 8.1 Hz, 2H), 7.09 (t, J = 7.4 Hz, 2H), 6.72 (M, 4H), 1.28-1.19 (m, 4H), 0.83 (m, 4H) , ≪ / RTI > J = 7.4 Hz, 6H). _{^{13 C NMR (CDCl 3):}} δ 185.10, 166.90, 149.39, 149.08, 146.30, 142.69, 141.51, 134.44, 125.72, 125.37, 123.62, 123.07, 119.87, 119.37, 100.84, 82.69 (CB-C), 79.91 (CB- C), 35.18, 31.78, 28.42, 22.31, 13.65. _{^{11 B NMR (CDCl 3):}} δ -2.8 (br s, 5B), -9.7 (br s, 15B). Mp = 358 < 0 > C. Analysis (C ₄₃ H ₅₉ B ₂₀ IrN ₂ O ₂ S ₂ ): C, 46.59; H, 5.36; N, 2.53 (calculated). C, 46.74; H, 5.35; N, 2.55 (experimental value).

Experimental Example  One : Optical physical  And electrochemical properties Example  1 to 2, Comparative Example  One)

division (C ^ N) λ _abs / nm
(ε × 10 ^-3 / M ^-1 cm ^-1 ) ^a λ _em / nm ^a τ / μs ^a Φ _em ^{a , b} E _ox / V ^c (D E _p / mV) E _red / V ^c (D E _p / mV) 298K 77K Example 1 (4- CBppy ) 261 (38.3), 279 (38.1), 353 (5.4), 390 (3.4), 415 (2.7), 474 (2.0), 509 531 524 3.0 0.02 0.51 (90) ^d -2.12 (270) ^e Example 2 (5- CBppy ) (48.4), 274 (43.1), 299 (33.4), 342 (10.1), 378 (4.8), 401 (3.9), 451 (2.4), 481 503 493 0.6 0.15 0.55 (140) ^d -2.19 (360) ^e Comparative Example 1 (4- fppy ) 259 (40.9), 287 (29.5), 331 (11.3), 393 (5.0), 444 (2.5), 474 493 483 1.5 0.40 0.46 Unobserved

The photophysical properties and the electrochemical characteristics of the phosphorescent compounds of Examples 1 and 2 and Comparative Example 1 were measured, and the results are shown in Table 1. Referring to the symbols in Table 1, the measurement conditions for each characteristic are as follows.

-a: Measured under degassed CH ₂ Cl ₂ (~ 10 ^-5 M)

-b: Measured according to the following equation (1) based on quantum efficiency (? = 0.55) of quinine sulfate (0.5 M, H ₂ SO ₄ )

[Equation 1]

Η is the refractive index of the solvent, A is the absorbance at the excitation wavelength, I is the integral area under the luminescence spectrum, s, r is the specimen and the reference value. The η value of CH ₂ Cl ₂ is 1.424 and the η value of 0.5 MH ₂ SO ₄ is 1.346.

-c: Measured under DMF (1 mM, scan rate = 100 mV / s) based on Fc / Fc + redox couple

-d: measured under reversible oxidation conditions

-e: Measured under quasi-reversing conditions

Referring to FIG. 4 (a), the phosphorescent compound of Example 1 exhibits a strong extinction band in the region of 250 to 350 nm, which may be due to the spin-tolerant? -Π * transition of the 4-CBppy ligand. Band shape, band energy, and high extinction coefficient were consistent with those observed for the free ligand, 4-CBppyH. A similar π-π * transition band was observed with a weak blue shift in Example 2. While the low energy band of the phosphorescent compound of Example 1 at 415 nm was due to the spin-tolerant MLCT (metal to ligand charge transfer), the band at 474 nm was attributed to the spin-suppression MLCT and the? -Π * transition of the 4-CBppy ligand . The MLCT band of Example 1 was significantly red shifted (393 and 444 nm) compared to Comparative Example 1 comprising four fluorine elements. Conversely, the lowest energy band of Example 2 was observed in the significantly blue shifted region (401 and 451 nm) compared to Example 1. This means that the carbene substitution for the 4 position of the phenyl ring lowers the excited state energy while the substitution for the 5 position increases the excited state energy. A similar tendency also appeared in the photoluminescence spectrum of Fig. 4 (b). Example 1 showed a red shifted emission band at the center of 531 nm, whereas Example 2 showed a blue shifted band at 503 nm. The luminescent lifetimes of Example 1 and Example 2 were 3.0 mu s and 0.6 mu s, respectively. Despite the electron deficiency characteristic of carboranes, the difference in the emission wavelength of about 40 nm between Example 1 and Comparative Example 1 is unusual, and the 13 nm blue shift shown in Example 2 is also remarkable. These results suggest that changes in the carbene substitution position for the phenyl ring may lead to phosphorescence color tuning.

Referring to FIG. 5, the phosphorescent compounds of Examples 1 and 2 undergo reversible oxidation at 0.51 V and 0.55 V. This oxidation potential shifts to the negative electrode according to Comparative Example 1. This means that the HOMO of Examples 1 and 2 is lower in energy than that of Comparative Example 1 due to effective stabilization of HOMO by the induction effect of carbene. Conversely, Example 1 and Example 2 exhibit chemically reversible but electrochemically quasi-reversible reduction processes. The aryl group substituted ortho-carboranes are generally subjected to a reduction process similar to that observed in Example 1 and Example 2, and such reduction characteristics may allow the carbene to participate in the pyridyl reduction. That is, carboranes can affect LUMO levels. Comparing the reduction potentials shown in FIG. 5, the reduction of Example 1 is the easiest, reflecting the remarkable LUMO stabilization in Example 1. These reduction behaviors of Example 1 and Example 2 were found to be related to the strong induction electron withdrawing effect of carboranes and the participation of carboranes to LUMO nonuniformity.

Experimental Example  2 : Optical physical  And electrochemical properties Example  3 to 4, Comparative Example  2)

division (C ^ N) λ _abs / nm
(ε × 10 ^-3 / M ^-1 cm ^-1 ) ^a λ _em / nm ^a Φ _PL
solution ^{a , b} /
film ^{c , d} τ / μs E _ox / V E _red / V 298K 77K film ^c solid solution film ^c solid Example 3 (5- MeCBbtp ) 288 (37.0), 338 (28.4), 374 (21.4), 522 (10.6) 644 636 644 671 0.05 / 0.13 1.17 3.66 0.19 0.55 ^{e, g} -1.76 ^{e, h} Example 4 (5- BuCBbtp ) 287 (35.0), 338 (25.7), 374 (19.1), 522 (9.3) 644 635 643 649 0.04 / 0.13 Comparative Example 2 (4- BuCBbtp ) 302 (34.7), 382 (15.8), 530 (5.0) - 641 644 657 - /0.01 - 0.50 0.19 0.50 ^{e, g} -1.66 ^{f, h}

The photophysical properties and the electrochemical characteristics of the phosphorescent compounds of Examples 3 to 4 and Comparative Example 2 were tested, and the results are shown in Table 2 above. Referring to the symbols in Table 2, the measurement conditions for each characteristic are as follows.

-a: measured under degassed THF (~ 10 ^-5 M)

-b: quinine sulfate (0.5M, H ₂ SO ₄₎ and the reference value to the quantum efficiency (Φ = 0.55) of the measures according to the equation 1, the value of η at this time, CH ₂ Cl ₂ was 1.424, 0.5 The η value of MH ₂ SO ₄ is 1.346.

-c: spin-coated PMMA film (8 wt% doped Ir (III) complex)

-d: Absolute value of PLQY ()

-e: Measured under DMF (1 mM, scan rate = 100 mV / s) based on Fc / Fc + redox couple

-f: measured at scan rate = 200 mV / s

-g: measured under reversible oxidation conditions

-h: Measured under quasi-reversible reduction conditions

Referring to FIG. 6, the phosphorescent compound of Example 3 exhibited a strong absorption band in the region of 270 to 400 nm, which was analyzed to be due to spin-tolerant? -Π * transition of the CBbtp ligand. Similar π-π * transition bands were also observed in the phosphorescent compound of Comparative Example 2. The broad low energy band in the 450-600 nm region is similar to that observed in (btp) ₂ Ir (acac) and can have a significant impact on mixed MLCT and MLCT transitions. The band positions (522 nm and 530 nm, respectively) of Example 3 and Comparative Example 2 were substantially red shifted compared to btp) ₂ Ir (acac), from which the carbene substitution for position 5 or 4 of the pyridine ring resulted in a bandgap It was confirmed that the energy was lowered. While the emission wavelengths of Example 3 and Comparative Example 2 were similar in film to 77 K, the specimen of Powdered Example 3 exhibited a red shifted emission band compared to that of Comparative Example 2. It is analyzed that Example 3 is due to aggregation in solid state and intermolecular π-π interaction occurs. In Comparative Example 2, it is analyzed that no such interaction is observed due to the steric effect of n-butyl group .

On the other hand, the absorption and the phosphorescence spectra of Example 4 were substantially identical except for the light-emitting band shifted in the solid state from that of Example 3, and the steric effect of the alkyl substituent of ortho-carbene was in the solid state, -π interactions in the sample. In addition, the phosphorescent compound efficiency of the phosphorescent compound of Example 4 was similar to that of Example 3, which means that the influence of the alkyl substituent on the photophysical properties of the complex is not greater than the position where it is substituted.

Referring to FIG. 7, the phosphorescent compounds of Example 3 and Comparative Example 2 undergo reversible oxidation at 0.55 V and 0.50 V, respectively. This oxidation potential is shifted to the cathode relative to (btp) ₂ Ir (acac) (0.36 V), and the energy level of the HOMO of the phosphorescent compound of Example 3 and Comparative Example 2 is lower than (btp) ₂ Ir (acac) Point. These results indicate that the HOMO level is stabilized by the induced pulling effect of carboranes. Conversely, the phosphorescent compounds of Example 3 and Comparative Example 2 were reduced at -1.76 and -1.66 V, respectively, which were chemically reversible but electrochemically quasi-reversible. The appearance of one high intensity anode peak for two oxidation peaks after reduction suggests that one 2-electron reduction can occur in Example 3 and Comparative Example 2 at a scan rate of 100-200 mV / s. This reduction behavior may allow carbene to be involved in pyridyl reduction. That is, carboranes can affect LUMO levels. Comparing the reduction potentials shown in FIG. 7, the reduction of Comparative Example 2 is easier than that of Example 3, indicating that carbene substitution at position 4 has a greater effect on LUMO stabilization than position 5 .

Experimental Example  3: Field  Performance Test of Light Emitting Device Example  1 to 2, Comparative Example  One)

The electric field and the device sequentially include ITO / NPB (40 nm) / CBP: light emitting layer (8 wt%) (30 nm) / BCP (10 nm) / Alq ₃ (40 nm) / LiF (1 nm) / Al And the light emitting layer is (4-CBppy) ₂ Ir (acac) or fac-Ir (ppy) ₃ ; NPB is N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) -benzidine (EM Index, Korea branch,> 99%, exp.); CBP is 4,4'-bis (9-carbazolyl) -biphenyl (Nichem,> 99%, exp.); BCP is Basocuproin (Lumtec, > 99.8%, Limited); Alq ₃ is tris (8-hydroxyquinolinolato) aluminum (EM Index,> 99%, limited edition). A hole-transporting NPB layer was deposited on a glass substrate previously coated with ITO using vacuum deposition (~ 10 ^-7 Torr). The CBP host layer was then deposited with the luminescent material under vacuum. The film thickness of the EML was determined using a TENCOR alpha-step 500 profiler. A positive hole blocking layer, an electron transporting Alq ₃ layer, and a positive electrode layer of LiF and Al were deposited on the EML. (Deposition _{rate: BCP, Alq 3 = 1 A} / s, LiF = 0.1 A / s, Al electrodes = 3 A / s).

The electroluminescence spectra were measured using a PR-650 spectrometer and current-voltage (JV) and luminance-voltage (LV) characteristics were measured using a current-voltage source (Keithley 237) and a luminescence detector (PR- . All electroluminescence measurements were made in a glove box filled with nitrogen at room temperature.

division emitter CIE
(x, y) ^b V _{turn - on}
(V) ^c L _max
(cd / m ² ) ^d EQE _max
(%) ^e PE _max
(lm / W) ^f Example 1 (4-CBppy) _2- Ir (acac) (0.392, 0.585) 4.6 13300 6.6 10.7 - fac- Ir (ppy) ₃ (0.330, 0.612) 3.4 40100 10.9 25.0

A performance test was conducted on the phosphorescent organic light emitting device to which Example 1 and fac- Ir (ppy) were applied as a phosphorescent compound, and the results are shown in Table 3 above. Referring to the symbols in Table 3, the measurement conditions for each characteristic are as follows.

-b: Measured under a current density of 10 mA / cm ²

-c: Measures the applied voltage under 1cd / m ² luminance condition

-d: Measures the maximum luminance

-e: Measured maximum external quantum efficiency

-f: Measures maximum power efficiency

Referring to FIG. 8, the phosphorescent organic electroluminescent device (hereinafter referred to as "phosphorescent organic electroluminescent device 1") doped with the phosphorescent compound of Example 1 emits green light very similar to the phosphorescent compound of Example 1, Was found to originate only from the phosphorescent compound of Example 1. Referring to FIG. 9, the phosphorescent organic light emitting device 1 exhibited a higher turn-on voltage (4.6 V) than the phosphorescent organic light emitting device doped with fac- Ir (ppy) ₃ . When the applied voltage was increased, the phosphorescent organic light emitting device 1 exhibited a current density and a luminance having a maximum brightness of 13,300 cd / m ² at 12.0 V. In the lifetime test, the phosphorescent organic light-emitting device 1 exhibited higher stability than the phosphorescent organic light-emitting device doped with fac- Ir (ppy) ₃ and exhibited higher external quantum efficiency (η _EQE , 6.6%) and power efficiency (η _PE , 10.7 lm / W).

Experimental Example  4 : Field  Performance Test of Light Emitting Device Example  3 to 4, Comparative Example  2)

An electroluminescent device was prepared on an ITO-coated glass substrate which had been pre-cleaned and plasma-treated. An aqueous dispersion of poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) (Baytron AI4083, HC Starck) was spin-coated on the substrate for 30 seconds at 2500 rpm, Lt; 0 > C for 10 minutes. The emissive layers composed of PNB-CBP mixed with (5-MeCBbtp) ₂ Ir (acac) or (4-BuCBbtp) ₂ Ir (acac) on the PEDOT: PSS layer Benzene (0.85 wt%) solution at 1500 rpm for 30 seconds. Thereafter, the sample was annealed on a 75 DEG C hot plate for 10 minutes. PNB-CBP is a polynorbornene (PNB) -based polymeric host containing CBP (9,9 '- (1,1'-biphenyl) -4,4'-dibis-9H- = 2.60 eV). The film thickness of the spin-coated layer was determined by AFM and measured at 30 nm. _{(5-MeCBbtp) 2 Ir (} acac) or _{(4-BuCBbtp) 2 Ir (} acac) is coated with a doped PNB-CBP specimen and PEDOT: PSS only the column evaporation chamber (HS-1100 coated samples, Digital Optics &Amp; Vacuum), and sealed with a glove box filled with nitrogen. A 30 nm thick CBP layer was deposited on a PEDOT: PSS specimen with 8 wt% (btp) ₂ Ir (acac) using a selective shadow mask.

Then, PNB-CBP doped with an organic layer [5-MeCBbtp) ₂ Ir (acac) or (4-BuCBbtp) ₂ Ir (acac) using a shadow mask exchanged with openings for all specimens, and (btp) ₂ Ir (acac)] was deposited on the light emitting layer. In this way, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 20 nm), Bphen (4,7-diphenyl-1,10-phenanthroline, LiF (1 nm), and Al (100 nm). Vacuum deposition was performed under high vacuum at BCP and Bphen, LiF, and Al electrodes at deposition rates of 0.5-1.0 A / s, 0.2 A / s, and 3 A / s, respectively.

The spectrum was measured using a fiber optic spectrometer (EPP2000, StellarNet) under a nitrogen atmosphere and the current density-voltage (JV) and luminance-voltage (Vs) were measured using a Source Measure Unit (Keithley 2400) and a calibrated photodiode (FDS100, Thorlab) (LV) characteristics were recorded.

division emitter conc. of emitter (wt%) host CIE (x, y) ^b V _{turn - on} (V) ^c L (cd / m ² ) ^d EQE _max (%) ^e PE _max (lm / W) ^f Example 3 5a 12 PNB-CBP ^g (0.693, 0.290) 4.4 93 3.8 0.6 Comparative Example 2 5b 12 PNB-CBP ^g (0.709, 0.287) 6.7 3 0.3 0.03 - 6 ( btp ) ₂ Ir (acac) 8 CBP ^h (0.682, 0.314) 3.4 671 12.0 7.5

A performance test was conducted on the phosphorescent organic light emitting device to which Example 3, Comparative Example 2 and 6 (btp) 2Ir (acac) were applied as a phosphorescent compound, and the results are shown in Table 4. Referring to the symbols in Table 4, the measurement conditions for each characteristic are as follows.

-b: Measured under a current density of 10 mA / cm ²

-c: Measures the applied voltage under 1cd / m ² luminance condition

-d: Measured luminance at a current density of 10 mA / cm ²

-e: Measured maximum external quantum efficiency

-f: Measures maximum power efficiency

-g: Spin coating

-h: vacuum deposition

Referring to FIG. 10, the phosphorescent organic light emitting device doped with the phosphorescent compound of Example 3 (hereinafter, referred to as "phosphorescent organic electroluminescent device 3") and the phosphorescent organic electroluminescent device doped with the phosphorescent compound of Comparative Example 2, It has been shown that it emits deep red light very similar to the electroluminescence spectrum, and it has been confirmed that this luminescence originates from each phosphorescent compound. The CIE color coordinate of the phosphorescent organic light emitting device 3 was located in a deep red region (x, y = 0.693, 0.290) as compared with the phosphorescent organic light emitting device (0.682, 0.314) to which 6 (btp) 2Ir (acac) was applied. According to electroluminescence characteristics, phosphorescent organic light emitting device 3 exhibited relatively good luminescence performance together with maximum external quantum efficiency (? _EQE = 3.8%) and power efficiency (? _PE = 0.6 lm / W). Even though the power efficiency of the phosphorescent organic light emitting device 3 is somewhat low, the external quantum efficiency was found to be similar to the PNBCBP red PhOLED device (eta _EQE = 3.4 to 5.1%) manufactured by the wet process. The low power efficiency of the phosphorescent organic light emitting device 3 was analyzed to be due to the low phosphorescent quantum efficiency of the phosphorescent compound of Example 3 and the relatively high driving voltage. In addition, although the current density was similar, the device doped with the phosphorescent compound of Comparative Example 2 showed significantly poorer device performance than the phosphorescent organic light emitting device 3. (η _EQE = 0.3%, η _PE = 0.03 lm / W) This is in agreement with the very weak phosphorescence characteristics of the phosphorescent compound of Comparative Example 2, and the effect of carboranes on LUMO at the 4th position of the pyridine ring is ortho- It was found that the triplet exciton was stabilized in combination with various properties of the CC bond of carboranes, which facilitates the non-radiative breakdown process, thereby lowering the electroluminescence efficiency.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (22)

A phosphorescent compound represented by the following formula
≪ Formula 1 >

In this formula,
Wherein said R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )
remind

end

,

, or

Lt;
Wherein said functional group (R) is selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t- butyl, n- pentyl, neopentyl, n- And biphenyl.
The process of claim 1 wherein said functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).
The process of claim 2 wherein said functional (R) substituted carbene group is

(Ortho-).
The phosphorescent compound according to claim 1, wherein the functional group (R) is a methyl group.
A phosphorescent compound represented by the following formula (2):
(2)

In this formula,
Wherein said R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )
remind

end

,

, or

Lt;
Wherein said functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Methylphenyl, and biphenyl.
6. The method of claim 5, wherein the functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).
The process of claim 6, wherein the functional (R) substituted carbene group is

(Ortho-).
The phosphorescent compound according to claim 5, wherein the functional group (R) is a methyl group.
A phosphorescent compound represented by the following formula (3):
(3)

In this formula,
Wherein said R-CB is a functional group (R) substituted carborane group (RC ₂ B ₁₀ H ₁₀ )
remind

this

or

Lt;
remind

end

,

, or

ego,
Wherein said functional group (R) is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Methylphenyl, and biphenyl.
The method of claim 9, wherein the functional (R) substituted carbene group is

(Ortho-),

(Meta-, meta-), and

(Para-, para-).
11. The method of claim 10, wherein the functional (R) substituted carbene group is

(Ortho-).
The phosphorescent compound according to claim 9, wherein the functional group (R) is a methyl group or an n-butyl group.
The phosphorescent compound according to claim 9, which is represented by the following general formula (4) or (5):
≪ Formula 4 >

≪ Formula 5 >

In this formula,
remind

end

,

, or

ego,
Wherein R is hydrogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, Biphenyl. ≪ / RTI >
The phosphorescent compound according to claim 13, wherein R is a methyl group or an n-butyl group.
A phosphorescent organic electroluminescent device comprising an anode, a cathode and an electroluminescent layer between both electrodes, wherein the electroluminescent compound according to any one of claims 1 to 14 is contained in the electroluminescent layer.
16. The organic electroluminescent device according to claim 15, wherein the anode is a transparent electrode, and the cathode is a metal electrode.
16. The organic electroluminescent device according to claim 15, further comprising a first charge transport layer between the anode and the light emitting layer.
18. The organic electroluminescent device according to claim 17, wherein the first charge transport layer comprises a hole injection layer and a hole transport layer.
19. The organic electroluminescent device according to claim 18, further comprising a second charge transport layer between the cathode and the light emitting layer.
The phosphorescent organic electroluminescent device according to claim 19, wherein the second charge transport layer comprises an electron transport layer and an electron injection layer.
The phosphorescent organic light emitting diode according to claim 20, further comprising a hole blocking layer between the light emitting layer and the electron transporting layer.
The organic electroluminescent device according to claim 21, further comprising an electron blocking layer between the light emitting layer and the hole transporting layer.

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