KR101706203B1 - Novel Red-emitting Iridium(III) Complexes with Hole Transporting Substitutent and Organic Light-Emitting Diodes Containing the Same - Google Patents

Abstract

The present invention relates to a novel red luminescent iridium (III) complex and an organic electroluminescent device comprising the same. More particularly, the present invention relates to a novel red luminescent iridium (III) complex compound having a quinoline and thiophene derivative as main ligands, (9H-carbazol-9-yl) phenyl) methanol, mCP (9H-carbazol-9-yl) (III) complex in which a picolinic acid derivative substituted with a substituted derivative thereof is introduced, and an organic electroluminescent device comprising the iridium (III) complex.
The iridium (III) complex according to the present invention is a red phosphorescent compound which is excellent in electrical stability, has high luminescence characteristics and brightness, and can realize color purity. It has excellent interfacial property with electrodes due to its improved solubility and heat resistance to organic solvents And is useful as a coloring material for an organic electroluminescent device.

Description

(Novel Red-emitting Iridium (III) Complexes with Hole Transporting Substituent and Organic Light-Emitting Diodes Containing the Same)

The present invention relates to a novel red luminescent iridium (III) complex and an organic electroluminescent device comprising the same. More particularly, the present invention relates to a novel red luminescent iridium (III) complex compound having a quinoline and thiophene derivative as main ligands, (9H-carbazol-9-yl) phenyl) methanol, mCP (9H-carbazol-9-yl) (III) complex in which a picolinic acid derivative substituted with a substituted derivative thereof is introduced, and an organic electroluminescent device comprising the iridium (III) complex.

2. Description of the Related Art Recently, as the size of a display device has been increased, a demand for a flat display device such as a liquid crystal display (LCD), a plasma display panel (PDP) and the like has increased. These planar display devices are slower in response speed than CRTs and have limited viewing angles, and research on other display devices is underway, one of which is an electroluminescent device.

Conventionally, an inorganic electroluminescent device using a luminescent phase which occurs when an electric field is applied to an inorganic semiconductor made of pn junction such as ZnS or CaS is used as a conventional electroluminescent device. However, in the case of an inorganic electroluminescent device, Since the device is fabricated in a vacuum state, it is difficult to increase the size of the device, and in particular, it is difficult to obtain a high-efficiency blue color.

Organic light-emitting diodes (OLEDs) using organic materials have been studied due to such problems. An organic electroluminescent device is a display using an organic material that emits light by itself. When an electric field is applied to an organic material, electrons and holes are transmitted from the cathode and the anode, respectively, and are bonded in the organic material. Lt; RTI ID = 0.0 > electroluminescence < / RTI > The organic electroluminescent device has a better viewing angle, lower power consumption, and a significantly improved response speed as compared with LCDs and the like, and is capable of processing high-quality images.

The emission of light in such an organic electroluminescent device can be largely divided into fluorescence and phosphorescence. When fluorescence occurs, the organic molecules emit light when the organic molecules fall from a single excited state to a ground state. Phosphorescence is a phenomenon in which organic molecules emit light when they fall from a triplet excited state to a ground state.

The electrophosphorescence device for phosphorescence capable of remarkably improving the luminous efficiency of the organic electroluminescent device was developed by SR Forrest Professor of Princeton University in USA and ME Thompson professor team of USC in 1999, - Orbital bonding is proportional to the fourth power of the atomic number, so it is known that complexes of heavy atoms such as platinum (Pt), iridium (Ir), europium (Eu), and terbium (Tb) In the case of the platinum complex, the lowest triplet exciton is a ligand-centered exciton (LC exciton) centered at the ligand, whereas the iridium complex is the triplet exciton with the lowest energy, which is the metal- ligand charge transfer, MLCT). Therefore, the iridium complex forms a larger spin-orbit coupling as compared with the platinum complex, resulting in a higher phosphorescence efficiency with a shorter triplet exciton lifetime.

In this regard, C. Adachi et al bis (2-phenylpyridine) iridium having green phosphorescent pigment into the central metal iridium () acetylacetonate [(ppy) 2 Ir (acac)] of 3-phenyl-4- (1'- naphthyl ) -5-phenyl-1,2,4-triazole (TAZ) to obtain a maximum luminous efficiency of 60 lm / W and a maximum internal quantum efficiency of 87%. In addition, US Universal Display Corp. (UDC) has announced that the green phosphorescent pigment is doped in the light emitting layer and a high luminous efficiency of 82 lm / W is achieved using the hole injecting material developed by LG Chem.

Organic electroluminescent devices for phosphorescence exhibiting blue, green and red colors have been developed, but organic electroluminescent devices for phosphorescence for three primary colors having excellent luminous efficiency, color coordinates and lifetime have not yet been developed.

US 7,250,512 discloses an Ir (btp) ₂ (acac) [Iridium (bis) 2- (2-benzothienyl) pyridinato-N, C2) (acetylacetonate) as an iridium complex However, new compounds are still required in terms of color purity, efficiency and solubility.

United States Patent No. 7,250,512

In order to solve the above problems,

(3,5-di (9H-carbazol-9-yl) carbodiimide derivative having quinoline and thiophene derivatives as main ligands and a halogen derivative or hole transporting property at para position relative to nitrogen atom of picolinic acid as auxiliary ligand (III), which exhibits a red phosphorescent light-emitting property and into which a picolinic acid derivative substituted with a [(3,5-di (9H-carbazol-9-yl) phenyl) And to provide a complex compound.

Another object of the present invention is to provide a process for producing the above iridium (III) complex.

Another object of the present invention is to provide an organic electroluminescent device including the iridium (III) complex in the light emitting layer.

In order to solve the above-mentioned problems, the present invention provides an iridium (III) complex represented by the following general formula (1)

[Chemical Formula 1]

(Wherein, in the above formula,

Ar is aryl or C ₃ to C ₂₀ heteroaryl of C ₆ to C ₂₀ ;

Z is O, S or Se;

R ₁ is hydrogen, halogen, C ₁ to C ₂₀ alkyl, C ₁ to C ₂₀ alkoxy, cyanide or nitro;

이고;R ₂ is halogen or

ego;

L ₁ is C ₁ to C ₂₀ alkyl;

Wherein said aryl and heteroaryl are each independently selected from the group consisting of halogen, hydroxy, C ₁ to C ₁₀ alkyl, C ₁ to C ₁₀ alkoxy, C ₃ to C ₂₀ cycloalkyl and C ₆ to C ₂₀ aryl Or more of the substituents;

Wherein said heteroaryl comprises at least one heteroatom selected from N, O and S.

(1) reacting a compound represented by the following general formula (2) with a compound represented by the following general formula (3) to obtain a quinoline derivative represented by the following general formula (4) and a thiophene derivative Producing a ligand compound;

Generating a cross-linked dimer (2) a halogen compound to the primary ligand of iridium halide hydrate (IrX ₃ 3H ₂ O) and the reaction; And

(3) synthesizing an iridium (III) complex represented by the following formula (1) by mixing and reacting the halogen-crosslinked dimer and a picolinic acid derivative represented by the following formula (5) Lt; RTI ID = 0.0 > of:

[Chemical Formula 1]

(Wherein, in the above formula,

Ar is aryl or C ₃ to C ₂₀ heteroaryl of C ₆ to C ₂₀ ;

Z is O, S or Se;

R ₁ is hydrogen, halogen, C ₁ to C ₂₀ alkyl, C ₁ to C ₂₀ alkoxy, cyanide or nitro;

이고;R ₂ is halogen or

ego;

L ₁ is C ₁ to C ₂₀ alkyl;

Wherein said aryl and heteroaryl are each independently selected from the group consisting of halogen, hydroxy, C ₁ to C ₁₀ alkyl, C ₁ to C ₁₀ alkoxy, C ₃ to C ₂₀ cycloalkyl and C ₆ to C ₂₀ aryl Or more of the substituents;

Wherein said heteroaryl comprises at least one heteroatom selected from N, O and S.

According to another aspect of the present invention, there is provided an organic electroluminescent device including an iridium (III) complex represented by Formula 1 in a light emitting layer.

The iridium (III) complex according to the present invention is a red phosphorescent compound, and quinoline and thiophene derivatives are introduced as main ligands. At the same time, as an auxiliary ligand, a halogen derivative or a hole transferring property A picolinic acid derivative substituted with 3,5-di (9H-carbazol-9-yl) phenyl] methanol [(3,5-di (9H-carbazol-9-yl) phenyl) methanol, mCP] So that not only excellent light emission characteristics and luminance characteristics but also high color purity can be realized. In addition, the iridium (III) complex according to the present invention has excellent interfacial characteristics with the electrode due to its improved solubility and heat resistance to an organic solvent, so that a solution process can be performed in the fabrication of an organic electroluminescent device.

1 is a cross-sectional view schematically showing a single layer type organic electroluminescent device to which an iridium (III) complex according to the present invention is applied.
FIG. 2 is a cross-sectional view schematically showing a multi-layer type organic electroluminescent device to which an iridium (III) complex according to the present invention is applied.
FIG. 3 is a graph showing the UV-visible absorption spectrum of iridium (III) complexes synthesized according to an embodiment of the present invention.
FIG. 4 is a graph showing photoluminescence (PL) intensity measurement results of iridium (III) complexes synthesized according to an embodiment of the present invention.
FIG. 5 is a graph showing electroluminescence (EL) intensity measurement results of an organic electroluminescent device including an iridium (III) complex compound synthesized according to an embodiment of the present invention.
6 is a graph showing current density-voltage-luminance characteristic measurement results of an organic electroluminescent device including an iridium (III) complex compound synthesized according to an embodiment of the present invention.
7 is a graph showing the results of measurement of external quantum efficiency for an iridium (III) complex synthesized according to an embodiment of the present invention.
8 is a graph showing the results of measurement of external quantum efficiency for the iridium complex according to the comparative test example of the present invention.

The present invention relates to a novel red luminescent iridium (III) complex and an organic electroluminescent device comprising the same. More particularly, the present invention relates to a novel red luminescent iridium (III) complex compound having a quinoline and thiophene derivative as main ligands, (9H-carbazol-9-yl) phenyl) methanol, mCP (9H-carbazol-9-yl) (III) complex in which a picolinic acid derivative substituted with a substituted derivative thereof is introduced, and an organic electroluminescent device comprising the iridium (III) complex.

Hereinafter, the present invention will be described in detail.

According to one aspect of the present invention, there is provided an iridium (III) complex represented by the following general formula (1): < EMI ID =

[Chemical Formula 1]

(Wherein, in the above formula,

Ar is aryl or C ₃ to C ₂₀ heteroaryl of C ₆ to C ₂₀ ;

Z is O, S or Se;

R ₁ is hydrogen, halogen, C ₁ to C ₂₀ alkyl, C ₁ to C ₂₀ alkoxy, cyanide or nitro;

이고;R ₂ is halogen or

ego;

L ₁ is C ₁ to C ₂₀ alkyl;

Wherein said aryl and heteroaryl are each independently selected from the group consisting of halogen, hydroxy, C ₁ to C ₁₀ alkyl, C ₁ to C ₁₀ alkoxy, C ₃ to C ₂₀ cycloalkyl and C ₆ to C ₂₀ aryl Or more of the substituents;

Wherein said heteroaryl comprises at least one heteroatom selected from N, O and S.

이고; 상기 L₁은 C₁ 내지 C₂₀인 알킬이다.Preferably, in the iridium (III) complex compound represented by Formula 1, Ar is C ₆ to C ₂₀ aryl; Z is S; R &_lt; ₁ > is hydrogen; R < _{2 >} is halogen or

ego; Wherein L ₁ is a C ₁ to C ₂₀ alkyl.

이다. More preferably, in the iridium (III) complex compound represented by Formula 1, R ₂ is fluoro, chloro, bromo, iodo or

to be.

Specifically, the iridium (III) complex represented by Formula 1 according to the present invention may be represented by the following compounds, but is not limited thereto.

,

,

The iridium (III) complex according to the present invention is a major ligand for determining the luminescence color in iridium complexes exhibiting phosphorescence characteristics. The iridium (III) complex can be obtained by introducing quinoline and thiophene derivatives as main ligands to realize a pure red luminescent color do.

In addition, in the iridium (III) complex of the present invention, a picolinic acid derivative is introduced as an auxiliary ligand in addition to the main ligand, and the solution can be easily dissolved in an organic solvent. Particularly, the picolinic acid derivative has a halogen derivative or a (3,5-di (9H-carbazol-9-yl) phenyl) methanol [ -di (9H-carbazol-9-yl) phenyl) methanol, mCP] derivative is substituted to improve luminescent color to improve color purity and improve luminescent efficiency.

As described above, the iridium (III) complex of the present invention is characterized in that quinoline and thiophene derivatives are introduced as main ligands, and at the same time, a halogen derivative at the para position relative to the nitrogen atom of picolinic acid as an auxiliary ligand Picolinic acid derivative substituted with 5-di (9H-carbazol-9-yl) phenyl] methanol [(3,5-di (9H-carbazol-9-yl) phenyl) methanol, mCP] Accordingly, the luminescent color and the luminous efficiency are greatly improved, and it can be easily dissolved in an organic solvent. Therefore, not only the luminescent area of a large area can be maintained, but also the excellent heat resistance, excellent interfacial characteristics with the electrode, And can be used as a light emitting material which realizes a pure red luminescent color.

According to another aspect of the present invention, there is provided a process for preparing a quinoline derivative of the formula (1), comprising reacting a compound represented by the following formula (2) with a compound represented by the following formula (3) Producing a ligand compound; Generating a cross-linked dimer (2) a halogen compound to the primary ligand of iridium halide hydrate (IrX ₃ 3H ₂ O) and the reaction; And (3) reacting the halogen-crosslinked dimer and a picolinic acid derivative represented by the following formula (5) to produce an iridium (III) complex represented by the following formula (1) ≪ RTI ID = 0.0 >

[Chemical Formula 1]

(Wherein, in the above formula,

Ar is aryl or C ₃ to C ₂₀ heteroaryl of C ₆ to C ₂₀ ;

Z is O, S or Se;

R ₁ is hydrogen, halogen, C ₁ to C ₂₀ alkyl, C ₁ to C ₂₀ alkoxy, cyanide or nitro;

이고;R ₂ is halogen or

ego;

L ₁ is C ₁ to C ₂₀ alkyl;

Wherein said aryl and heteroaryl are each independently selected from the group consisting of halogen, hydroxy, C ₁ to C ₁₀ alkyl, C ₁ to C ₁₀ alkoxy, C ₃ to C ₂₀ cycloalkyl and C ₆ to C ₂₀ aryl Or more of the substituents;

Wherein said heteroaryl comprises at least one heteroatom selected from N, O and S.

Preferably, the iridium (III) complex thus prepared is a compound in which the quinoline and thiophene derivatives are introduced as main ligands and the halogen derivative or mCP derivative is substituted at the para position with respect to the nitrogen atom of the picolinic acid as an auxiliary ligand (III) red phosphorescent compound into which a picolinic acid derivative is introduced.

The synthesis mechanism according to an embodiment of the present invention can be expressed as follows.

Further, the iridium (III) complex of the present invention can realize a pure red luminescent color and can be used as a dopant of a luminescent layer, thereby making it possible to manufacture an organic electroluminescent device for phosphorescence capable of a red solution process.

Thus, according to another aspect of the present invention, there is provided an organic electroluminescent device including an iridium (III) complex represented by Formula 1 in the light emitting layer.

More specifically, the organic electroluminescent device includes a first electrode and a second electrode opposed to the first electrode, wherein the emission layer includes an organic electroluminescent (EL) layer stacked between the first electrode and the second electrode Device.

The organic electroluminescent device of the present invention may further include a hole injecting layer and a hole transporting layer between the first electrode and the light emitting layer, and an electron transporting layer and an electron transporting layer between the light emitting layer and the second electrode.

In addition, the iridium (III) complex of the present invention may be included as a dopant of the light emitting layer, and the iridium (III) complex may be included in an amount of 3 to 20 wt% based on the total amount of the light emitting layer. The efficiency is remarkably lowered due to the aggregation or dilution effect of the dopant of the light emitting layer when the light emitting layer is contained in the light emitting layer above or below the above range and the characteristics of the thin film are very bad due to the phase separation of the light emitting layer, And so on.

Hereinafter, a method of manufacturing an organic electroluminescent device according to the present invention will be described.

FIG. 1 schematically shows a single-layer type organic electroluminescent device 1000 to which the above-described iridium complex can be applied according to an embodiment of the present invention. The organic electroluminescent device 1000 having a single layer structure has a structure in which a substrate 1100, a first electrode 1110, a light emitting layer 1140, and a second electrode 1170 are sequentially stacked. The substrate 1100 may be made of a material such as glass or plastic, for example.

In particular, the first electrode 1110 may be formed of 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 And conductive polymers such as polyaniline and polythiophene may be used. According to a preferred embodiment, ITO is used.

The second electrode 1170 is an effective material for injecting electrons, which are negative-charged carriers, and is formed of gold, aluminum, copper, silver, or an alloy thereof; Aluminum, indium, calcium, barium, magnesium and alloys thereof, such as calcium / aluminum alloys, magnesium / silver alloys, aluminum / lithium alloys and the like; Or a metal belonging to rare earth, lanthanide or actinide, preferably aluminum, or aluminum / calcium alloy.

Hosts having phosphorescent properties that may be used in connection with the present invention include aryl amines, carbazole, spiro. Specific examples thereof include 4,4-N, N-dicarbazole-biphenyl, CBP, N, N-dicarbazoyl- (4-carbazoyl-9-ylphenyl) amine, TCTA), poly (vinylcarbazole) , PVK), polyfluorene, 4,4'-bis [9- (3,6-biphenylcarbazolyl)] -1,1'-biphenyl 4,4'-bis [9- -Biphenylcarbazolyl)] - 1-1, 1'-biphenyl, 9,10-bis [(2 ', 7'- tert- butyl) -9', 9 "-spirobifluorenyl ) Anthracene, tetrafluorene, and the like, and TCTA can be preferably used.

The light emitting layer 1140 of the present invention is laminated to the upper portion of the first electrode 1110 with a thickness of approximately 5 to 200, preferably 50 to 100. The iridium complex according to the present invention may be used as a dopant for the light emitting layer 1140 3 to 20% by weight, more particularly 5 to 20% by weight.

Meanwhile, the iridium complex according to the present invention includes not only the single layer organic electroluminescent device 1000 described above but also a multi-layer organic electroluminescent device having a separate layer for electron / hole transport between the light emitting layer and the electrode. FIG. 2 schematically shows a cross section of a multilayer organic electroluminescent device 2000 to which an iridium complex compound synthesized according to the present invention can be applied. The organic electroluminescent device 2000 includes a substrate 2100, a first electrode 2110, a hole injection layer (HIL) 2120, a hole transporting layer (HTL) 2130, A light emitting layer 2140, an electron transporting layer (ETL) 2150, an electron injection layer (EIL) 2160, and a second electrode 2170 are sequentially stacked.

The hole injection layer 2120 stacked between the first electrode 2110 and the light emitting layer 2140 in the multilayer organic electroluminescent device 2000 may be formed of ITO used as the first electrode 2100, Not only improves the interfacial property between the organic materials used as the transfer layer 2130 but also functions to smooth the surface of the ITO by being coated on the upper surface of the ITO whose surface is not flat. In particular, the hole injection layer 2120 may be formed by adjusting the work function level of the ITO and the hole transport layer 2130 to adjust the difference between the work function level of ITO and the HOMO level of the hole transport layer 2130, ) ≪ / RTI > as the material having a median value of the HOMO level. The hole injecting layer 2120 may be made of copper phthalocyanine (CuPc), N, N'-dinaphthyl-N, N'-phenyl- (1,1'- diamine, NPD), 4,4 ', 4' '- tris [methylphenyl (phenyl) amino] triphenyl amine (m-MTDATA), 4,4' (1-TNATA), 4,4 ', 4 "-tris [2-naphthyl (phenyl) amino] triphenyl amine (2-TNATA), 1,3,5-tris [N- (4-diphenylaminophenyl) phenylamino benzene (p-DPA-TDAB), poly (3,4-ethylenedioxythiophene) -poly (styrnesulfonate) (PEDOT) which is a polythiophene derivative as a conductive polymer can be used. In the embodiment of the present invention, PEDOT Were used. The hole injection layer 2120 may be coated on the first electrode 2110 with a thickness of 20 to 200 nm.

A hole transporting layer 2130 is formed on the hole injecting layer 2120 so that the holes introduced through the hole injecting layer 2120 can be stably supplied to the light emitting layer 2140. A material whose HOMO level of the hole transport layer 2130 is higher than the HOMO level of the light emitting layer 2140 is selected. In connection with the present invention, materials usable for the hole transport layer 2130 include N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'- diamine (TPD), N, N'-bis (1-naphthyl) -N, N'-biphenyl- [1,1'-biphenyl] -4,4'- bis (4-methylphenyl) methane (MPMP), bis [4- (N, N-diethylamino) -2-methylphenyl] ), N, N'-bis (4-methylphenyl) -N (N, N ', N'-tetrakis A low molecular weight hole transporting material such as N'-bis (4-ethylphenyl) - [1,1 '- (3,3'- dimethyl) biphenyl] -4,4'-diamine (ETPD); A polymer hole transporting material such as polyvinylcarbazole, polyaniline, or (phenylmethyl) polysilane may be used. The hole injection layer 2130 may be deposited to a thickness of about 10 to 100 on top of the hole injection layer 2120 .

An electron injecting layer 2160 and an electron transporting layer 2150 which correspond to the hole injecting layer 2120 and the hole transporting layer 2130 are formed between the light emitting layer 2140 and the second electrode 2170 . Unlike the other charge transporting layers, the electron injection layer 2160 is used to induce smooth electron injection. In contrast to other charge transporting layers, alkali metal or alkaline earth metal ion forms such as LiF, BaF ₂ , and CsF are used. Gt; 2150 < / RTI >

The electron transport layer 2150 is mainly composed of a material containing a chemical component that attracts electrons, which requires high electron mobility and stably supplies electrons to the light emitting layer 2140 through smooth electron transport. The electron transport layer that can 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-oxadisole (PBD) Azole compounds such as 1,2,4-triazole (TAZ); phenylquinazoline; 1, 3 ', 5'- [3- (3-Pyridinyl) phenyl] [1,1': 3 ', 1''- terphenyl] -3,3'-diyl] bispyridine (TmPyPB) 3,5-Tri (1-phenyl-1H-benzo [d] imidazol-2-yl) phenyl (TPBi). In an embodiment of the present invention, TPBi is used as the electron transport layer 2150, and the electron transport layer 2150 may be deposited on the emission layer 2140 at a thickness of 5 to 150 nm.

Hereinafter, exemplary embodiments of the novel iridium (III) complex according to the present invention, a method for producing the iridium (III) complex and a luminescent property of the device will be described. However, the following examples serve to help understanding the present invention. The present invention is not limited to the following examples.

<Examples>

Example 1: Preparation of a chloride-bridged dimer

The synthesis mechanism of 4-phenyl-2- (thiophen-2-yl) quinoline according to this example is as follows.

Preparation of 4-phenyl-2- (thiophen-2-yl) quinoline

First, a three-necked flask equipped with a nitrogen atmosphere was charged with 1.43 g (11.3 mmol) of 1- (thiophene-2-yl) ethanone and 2.46 g 3.41 g (13.6 mmol) of diphenylphosphate and 8.0 mL of metacresol [m-Cresol] were added, stirred at room temperature for 20 minutes, and then refluxed at 140 DEG C for 12 hours. Then, the three-necked flask was cooled to room temperature, and 60 mL of methylene chloride and 30 mL of a 10% aqueous solution of sodium hydroxide (NaOH) were added to separate the organic layer. The organic layer thus obtained was washed several times with distilled water, dried using magnesium sulfate, and then separated by column chromatography using hexane and ethyl acetate to obtain 4-phenyl-2 (Yield: 77%) of [4-phenyl-2- (thiophene-2-yl) quinoline]. The results of ¹ H NMR and ¹³ C NMR analyzes of the obtained compound are shown below.

_{^{1 H NMR (CDCl 3):}} (ppm) 7.41-7.47 (m, 2H), 7.08-7.19 (m, 3H), 6.83-6.95 (m, 2H), 3.89-3.84 (t, J = 7.8Hz, 2H ), 2.58 (s, 3H), 1.82 (m, 2H), 1.25 (m, 4H), 0.98 (t, J = 6.6 Hz, 3H);

¹³ C NMR (CDCl ₃ ): (ppm) 199.8, 144.9, 144.8, 136.1, 132.1, 132.0, 128.2, 122.7, 119.7, 118.9, 47.4, 31.5, 29.3, 27.5, 27.0, 22.7, 14.1

Preparation of Chloride-bridged Dimer

5.0 g (17.40 mmol) of 4-phenyl-2- (thiophen-2-yl) quinoline obtained above and 2.08 g (6.96 mmol) of iridium chloride hydrate (IrCl ₃ 3H ₂ O) Ethoxyethanol) and distilled water (3: 1 v / v), and the mixture was stirred at 140 ° C for 24 hours. Subsequently, the stirred solution was cooled to room temperature, and the resulting yellow solid was filtered and washed well with a water-ethanol solution (3: 1 v / v) to obtain 3.36 g of chlorine-bridged dimer (yield: 60 %).

Example 2. Synthesis of an iridium (III) complex [(Th-PQ) 2-thiophene-2-yl) quinoline primary ligand and an auxiliary ligand of 4-chloropicolinic acid ₂ Ir (4-pic-Cl)]

The synthesis mechanism of the iridium (III) complex [(Th-PQ) ₂ Ir (4-pic-Cl)] according to this embodiment is as follows.

Chlorine obtained from Example 1-crosslinked dimer 2.3g (1.44 mmol), 4- chloro avoid collision acid _{0.68g (4.31 mmol), K 2} CO 3 1.99g of 20 mL of 2-ethoxyethanol in (14.4 mmol) And the mixture was refluxed at a temperature of 25 DEG C for 8 hours. Then, the refluxed solution was cooled to room temperature, and the resulting solid was filtered and washed well with a water-ethanol solution (3: 1 v / v) to obtain an iridium (III) salt solution having 4-chloropicolinic acid introduced as an auxiliary ligand. 0.84 g (yield: 63%) of the complex was obtained.

Hereinafter, the iridium (III) complex obtained through this example is abbreviated as "(Th-PQ) ₂ Ir (4-pic-Cl)". ¹ H NMR , ¹³ C NMR and HRESI-MS analysis results are shown below.

_{^{1 H NMR (300MHz, CDCl 3}} ): (ppm) 8.73-8.70 (d, 1H), 7.96 (s, 1H), 7.85-7.83 (d, 1H), 7.75-7.72 (d, 2H), 7.67-7.63 (m, 3H), 6.96-6.95 (m, 1H), 6.66-6.64 (m, 1H), 7.31-7.33 (m, 3H), 7.22-7.15 , 6.19-6.17 (m, 1 H);

¹³ C NMR (300 MHz, CDCl ₃ ): (ppm) 171.8, 166.6, 165.2, 154.38, 152.91, 152.82, 151.57, 149.80, 148.96, 147.64, 146.51, 141.52, 139.29, 137.40, 137.36, 134.79, , 130.09, 130.01, 129.87, 129.27, 129.13, 128.98, 128.34, 128.27, 126.52, 126.36, 125.88, 125.68, 124.94, 124.79, 117.98, 116.9; Calcd for C ₄₄ H ₂₇ ClIrN ₃ O ₂ S ₂ : C, 57.35; H, 2.95; N, 4.56. Found: C, 57.24; H, 2.82; N, 4.52.

HRESI-MS [M + H] &lt; ⁺ &gt;: m / z found 921.4926, calcd for 921.49.

Example 3: Auxiliary of picolinic acid derivatives substituted with 4-phenyl-2- (thiophen-2-yl) quinoline primary ligand and (3,5-di (9H-carbazol- Iridium (III) complex with ligand [(Th-PQ) ₂ Synthesis of Ir (4-pic-mCP)

1.0 g (1.09 mmol) of the iridium (III) complex [(Th-PQ) ₂ Ir (4-pic-Cl)] obtained in Example 2, Phenyl) methanol, 452 mg (3.27 mmol) of K ₂ CO ₃ and 20 mL of DMF were added to the solution, and the mixture was refluxed in a nitrogen atmosphere at 80 ° C. for 8 hours. After confirming that the reaction was completed, the reaction product was cooled, and the solution was poured into 100 mL of distilled water, extracted three times with 50 mL of methylene chloride, and water was removed with anhydrous MgSO ₄ . Subsequently, the product was separated by column chromatography at a ratio of ethyl acetate-hexane (1: 4 v / v) to give picolor substituted with (3,5-di (9H-carbazol-9-yl) phenyl) 0.59 g (yield: 44%) of iridium (III) complex compound into which a nitric acid derivative was introduced was obtained.

The iridium (III) complex obtained through this example is abbreviated as "(Th-PQ) ₂ Ir (4-pic-mCP)" and ¹ H NMR And HRESI-MS analysis results are shown below.

¹ H NMR (300 MHz, CDCl ₃ ): (ppm) 8.80-8.77 (d, 1 H), 8.17-8.15 (m, 4H), 7.88 2H), 7.51 (s, 2H), 7.48-7.40 (m, 4H), 7.38-7.31 (m, 5H), 7.68-7.66 (m, 2H), 6.92-6.90 (d, 1H), 6.70-6.68 (m, 2H), 7.28 d, 1 H), 6.22-6.20 (d, 1 H), 5.28 (s, 2 H); Calcd for C ₇₅ H ₄₈ IrN ₃ O ₃ S ₂ : C, 68.06; H, 3.66; N, 5.29. Found: C, 68.04; H, 3.65; N, 5.25.

HRESI-MS [M + H] &lt; ⁺ &gt;: m / z found 1323.2873 calcd for 1323.56.

Comparative Example 1: Synthesis of iridium (III) complex (Th-PQ) having an auxiliary ligand with 4-phenyl-2- (thiophen-2-yl) quinoline primary ligand and picolinic acid ₂ Synthesis of Ir (pic)

Ethoxyethanol (1.5 mL) was added to 49.4 mg (0.048 mmol) of the chlorine-crosslinked dimer obtained in Example 1 and 15 mg (0.12 mmol) of picolinic acid, and the mixture was refluxed at 25 ° C for 20 hours. Then, the refluxed solution was cooled to room temperature, and the resulting solid was filtered and washed with water-ethanol (3: 1) to obtain 20.5 mg of iridium (III) complex in which picolinic acid was introduced as an auxiliary ligand 71%).

Hereinafter, the iridium (III) complex obtained through this Comparative Example is abbreviated to "(Th-PQ) ₂ Ir ₍ pic)". ¹ H NMR and ¹³ C NMR of the iridium (III) The results of the analysis are shown below.

¹ H NMR (300 MHz, CDCl ₃ ): (ppm) 9.01 (d, J = 6 Hz, 2H), 7.59-7.78 (m, 10H), 7.36-7.47 (T, J = 7.2 Hz, 4H), 1.62 (m, 6H), 1.50 (m, 4H), 6.83-6.86 (t, J = 7.8 Hz, 2H) , 1.26-1.34 (m, 12H), 0.98 (m, 6H);

^{13 C NMR (300 MHz, CDCl} 3): (ppm) 158.1, 150.5, 148.9, 146.0, 144.9, 145.4, 139.0, 137.9, 135.1, 132.1, 132.0, 129.9, 129.3, 128.9, 128.5, 128.3, 128.2, 127.4, 127.3. 127.0, 119.7, 119.4, 118.8, 118.3, 117.6, 117.0, 116.9, 108.8, 102.4, 59.0, 47.4, 31.5, 27.5, 27.0, 26.6, 25.6, 22.7, 14.1; Calcd for C ₇₁ H ₆₅ IrN ₄ O ₂ S ₂ : C, 66.47; H, 4.65; N, 4.70. Found: C, 66.27; H, 4.73; N, 4.72.

Test Example 1: Measurement of absorption spectrum of iridium (III) complex

The UV-visible absorption spectrum was measured using a Shimadzu UV-3100 spectrometer in the chloroform-dissolved form of the luminescent material (Th-PQ) ₂ Ir (4-pic-mCP) And the results are shown in Fig.

Referring to FIG. 3, in the UV absorption peak of the iridium (III) complex (Th-PQ) ₂ Ir (4-pic-mCP), transition of phenylquinoline and thiophene derivative occurs at a wavelength shorter than about 440 nm , And the charge transfer state between the single metal and the center metal ligand of the triplet occurs at about 500 nm, which is the long wavelength.

Test Example 2: Measurement of photoluminescence in solution state of iridium (III) complex

Photoluminescence (PL) was measured with a Hitachi F-4500 in the state where the light emitting material of (Th-PQ) ₂ Ir (4-pic-mCP), an iridium (III) complex synthesized in Example 3, was dissolved in chloroform . The PL was measured with the excitation wavelength of the UV absorption maximum measured in the iridium-based light emitting material, and the results are shown in FIG.

4, in the optical luminescence of the iridium (III) complex (Th-PQ) ₂ Ir (4-pic-mCP), the maximum emission peak at 610 nm was formed and a pure red emission color I could confirm.

Test Example 3: Characterization of OLED device including iridium (III) complex

Using the iridium (III) complex of _{(Th-PQ) 2 Ir (} 4-pic-mCP) and _{(Th-PQ) 2 Ir (} pic) synthesized in Example 3 and Comparative Example 1 ITO / PEDOT: PSS / TCTA: TPBi: iridium complex compound OLED devices of nm / TPBi / LiF / Al type were fabricated, and EL spectrum (Hitachi F-4500 fluorescence spectrophotometer), current density-voltage- 238, CS-1000, LS-100) and the external quantum efficiency according to the luminance were measured. The measurement results are shown in FIGS. 5 to 7.

Further, as a comparative test, ITO (biphenyltetracarboxylic dianhydride) in which Ir (btp) ₂ (acac) [Iridium (III) bis / NPD / CBP: Ir (btp) ₂ (acac) / BCP / Alq ₃ / MgAg / Ag type OLED device was manufactured and the external quantum efficiency according to the luminance was measured. The measurement result is shown in FIG.

5 is an organic electroluminescence comprising an iridium (III) complex of _{(Th-PQ) 2 Ir (} 4-pic-mCP) and _{(Th-PQ) 2 Ir (} pic) synthesized in Example 3 and Comparative Example 1 The EL spectrum of (Th-PQ) ₂ Ir (4-pic-mCP) and (Th-PQ) ₂ Ir (pic) in the light emitting device shows the maximum emission peak at 623 nm, (0.674, 0.322). Thus, in comparison with the Ir (btp) ₂ (acac) of the prior art (US 7,250,512) exhibiting a maximum emission at about 620 and an emission peak at 675 nm, the iridium complex according to the present invention exhibits a maximum emission peak at 623 nm And thus it was confirmed that red luminescence characteristics and color purity were further improved.

Further, Figure 6 is an organic light emitting containing the iridium complex of _{(Th-PQ) 2 Ir (} 4-pic-mCP) and _{(Th-PQ) 2 Ir (} pic) synthesized in Example 3 and Comparative Example 1 in the _{device, (Th-PQ) 2 Ir} (4-pic-mCP) and (Th-PQ) ₂ current density Ir (pic) - voltage - illustrates the luminance _{property, (Th-PQ) 2 Ir} (pic and the driving voltage of (Th-PQ) ₂ Ir (pic) is about 8.72 V and 8.53 V, respectively, and the maximum luminance is 3013 cd / m ² and 2985 cd / m &lt; ² &gt;.

Further, Figure 7 is an organic light emitting containing the iridium complex of _{(Th-PQ) 2 Ir (} 4-pic-mCP) and _{(Th-PQ) 2 Ir (} pic) synthesized in Example 3 and Comparative Example 1 in the _{device, (Th-PQ) 2 Ir} (4-pic-mCP) and (Th-PQ) illustrates the external quantum efficiency in accordance with the brightness of _{2 Ir (pic), (Th} -PQ) 2 Ir (pic- mCP) and (Th-PQ) ₂ Ir (pic) were 11.77% and 7.13%, respectively. In the iridium complex of the same structure, the hole transport properties of picolinic acid at position 4 it was found that the maximum quantum efficiency characteristic was excellent when mCP was introduced.

8 shows the external quantum efficiency according to the luminance of Ir (btp) ₂ (acac) in an organic electroluminescent device including Ir (btp) ₂ (acac) %.

1000, 2000: organic electroluminescence device 1100, 2100: substrate
1110, 2110: First electrode 2120: Hole injection layer
2130: hole transport layer 1140, 2140: light emitting layer
2150: electron transport layer 2160: electron injection layer
1170, 2170: second electrode

Claims (11)

An iridium (III) complex characterized by being the following compound.

delete delete delete delete delete An organic electroluminescent device comprising the luminescent layer with an iridium (III) complex according to claim 1. 8. The method of claim 7,
Wherein the organic electroluminescent device comprises a first electrode and a second electrode opposed to the first electrode, and the light emitting layer is stacked between the first electrode and the second electrode. device. 8. The method of claim 7,
A hole injecting layer and a hole transporting layer between the first electrode and the light emitting layer, and an electron transporting layer between the light emitting layer and the second electrode. 8. The method of claim 7,
And the iridium (III) complex as a dopant of the light emitting layer. 11. The method of claim 10,
Wherein the iridium (III) complex comprises 3 to 20% by weight based on the total weight of the light emitting layer.

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