Iridium complexes and organic electroluminescence device using the same

Abstract

The present invention discloses an iridium complexes and the organic EL device employing the iridium complexes as light emitting guest of emitting layer can display good performance like as lower driving voltage and power consumption, increasing efficiency and half-life time. Additional, the present invention provide the suitable emitting host (H1 to H6) to collocate with the energy level of iridium complexes for the present invention. Also provided a novel preparation method to synthesize the novel ligand such as 6-bromo-3,3-dimethyl-1-phenyl-1,3-dihydroindeno[2,1-b]carbazole.

Claims

1. An iridium complex is represented by the following formula (1): ##STR00031## wherein m represents an integer of 1 or 2, X represents a divalent bridge selected from the group consisting of O, S and N(R.sub.7), A ring represents a substituted or unsubstituted benzene ring, Y.sub.1 and Y.sub.2 are different and Y.sub.1, Y.sub.2 represent nitrogen or carbon atom; R.sub.1 to R.sub.7 are the same or different, R.sub.1 to R.sub.7 are independently selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

2. The iridium complex according to claim 1, wherein the iridium complex formula (1) is represented by the following formula (2) to formula (7): ##STR00032## ##STR00033## wherein X represents a divalent bridge selected from the group consisting of O, S and N(R.sub.7), R.sub.1 to R.sub.7 are the same or different, R.sub.1 to R.sub.7 independently selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

3. An organic electroluminescence device comprising a pair of electrodes consisting of a cathode and an anode, and between the pairs of electrodes comprising at least a light emitting layer, one or more layers of organic thin film layer, wherein the light emitting layer comprising the iridium complex for an organic electroluminescence device according to claim 1.

4. The organic electroluminescence device according to claim 3, wherein the light emitting layer comprising the iridium complex with a general formula (1) is a phosphorescent guest material.

5. The organic electroluminescent device according to claim 3, wherein the light emitting layer comprising two or three types of emitting host with the following formulas: ##STR00034## wherein X is a divalent bridge selected from the group consisting of O, S, C(R.sub.8).sub.2, N(R.sub.9) and Si(R.sub.10).sub.2, m represents an integer of 0 to 4, n represents an integer of 0 to 8, R.sub.1 to R.sub.4 and R.sub.8 to R.sub.10 are independently selected from the group consisting of a hydrogen atom, a halide, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

6. The organic electroluminescent device according to claim 3, wherein the light emitting host is selected from the group consisting of: ##STR00035## ##STR00036##

7. The organic electroluminescent device according to claim 3, wherein the light emitting layer emits phosphorescent green and yellow lights.

8. The organic electroluminescent device according to claim 3, wherein the device is an organic light emitting device.

9. The organic electroluminescent device according to claim 3, wherein the device is a lighting panel.

10. The iridium complex according to claim 1 with a general formula (1) is selected from the group consisting of: ##STR00037## ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 show one example of organic EL device in the present invention, wherein 6 is transparent electrode, 14 is metal electrode, 7 is hole injection layer which is deposited onto 6, 8 is hole transport layer which is deposited onto 7, 9 is electron blocking layer which is deposited onto 8, 10 is fluorescent or phosphorescent emitting layer which is deposited onto 9, 11 is hole blocking layer which is deposited onto 10, 12 is electron transport layer which is deposited onto 11, and 13 is electron injection layer which is deposited onto 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) What probed into the invention is the iridium complexes and organic EL device using the iridium complexes. Detailed descriptions of the production, structure and elements will be provided in the following to make the invention thoroughly understood. Obviously, the application of the invention is not confined to specific details familiar to those who are skilled in the art. On the other hand, the common elements and procedures that are known to everyone are not described in details to avoid unnecessary limits of the invention. Some preferred embodiments of the present invention will now be described in greater detail in the following. However, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, that is, this invention can also be applied extensively to other embodiments, and the scope of the present invention is expressly not limited except as specified in the accompanying claims.

(3) In a first embodiment of the present invention, iridium complexes which can be used as phosphorescent guest material of emitting layer for organic EL device are disclosed. The mentioned iridium complexes is represented by the following formula (1):

(4) ##STR00002##
wherein m represents an integer of 1 or 2, X independently represents a divalent bridge selected from the atom or group consisting from O, S and N(R.sub.7), A ring represents a substituted or unsubstituted benzene ring, Y.sub.1 and Y.sub.2 are different and Y.sub.1, Y.sub.2 represent nitrogen or carbon atom; R.sub.1 to R.sub.7 are the same or different, R.sub.1 to R.sub.7 independently selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

(5) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes is represented as the following formula (2):

(6) ##STR00003##
in the above-mention formula (2), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(7) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes are represented as the following formula (3):

(8) ##STR00004##
in the above-mention formula (3), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(9) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes are represented as the following formula (4):

(10) ##STR00005##
in the above-mention formula (4), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(11) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes are represented as the following formula (5):

(12) ##STR00006##
in the above-mention formula (5), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(13) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes are represented as the following formula (6):

(14) ##STR00007##
in the above-mention formula (6), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(15) The iridium complexes according to the above-mentioned formula (1), wherein the iridium complexes are represented as the following formula (7):

(16) ##STR00008##
in the above-mention formula (7), wherein X and R.sub.1 to R.sub.6, each is the same as the described in the formula (1).

(17) In this embodiment, some specific iridium complexes are shown below:

(18) ##STR00009## ##STR00010## ##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016##

(19) Detailed preparation for the iridium complexes in the present invention could be clarified by exemplary embodiments, but the present invention is not limited to exemplary embodiments. EXAMPLE 1 show the preparation for examples of the derivative in the present invention. EXAMPLE 2 shows the fabrication of organic EL device and I-V-B, half-life time of organic EL device testing report.

EXAMPLE 1

Synthesis of EX11

Synthesis of 3-bromo-9,9-dimethyl-6-(2-nitrophenyl)-9H-fluorene

(20) ##STR00017##

(21) A mixture of 35.2 g (100 mmol) of 3,6-dibromo-9,9-dimethyl-9H-fluorene, 18.4 g (110 mmol) of 2-nitrophenylboronic acid, 2.31 g (2 mmol) of Pd(PPh.sub.3).sub.4, 75 ml of 2M Na.sub.2CO.sub.3, 150 ml of EtOH and 300 ml toluene was degassed and placed under nitrogen, and then heated at 100 C. for 24 h. After finishing the reaction, the mixture was allowed to cool to room temperature. The organic layer was extracted with ethyl acetate and water, dried with anhydrous magnesium sulfate, the solvent was removed and the residue was purified by column chromatography on silica gel to give product (30.7 g, 78.0 mmol, 78%) as a white solid.

Synthesis of 6-bromo-3,3-dimethyl-1,3-dihydroindeno[2,1-b] carbazole

(22) ##STR00018##

(23) A mixture of 30.7 g (78 mmol) of 3-bromo-9,9-dimethyl-6-(2-nitrophenyl)-9H-fluorene, 200 ml of triethylphosphite, 100 ml of 1,2-dichlorobenzene, was placed under nitrogen, and then heated at 160 C. overnight. After finishing the reaction, the mixture was allowed to cool to room temperature. Than 1200 ml of MeOH was added, while stirring and the precipitated product was filtered off with suction. To give 7.9 g (yield 28%) of yellow product which was purified by column chromatography on silica gel (Hx-CH.sub.2Cl.sub.2).

Synthesis of 6-bromo-3,3-dimethyl-1-phenyl-1,3-dihydro indeno[2,1-b]carbazole

(24) ##STR00019##

(25) A mixture of 7.9 g (21.8 mmole) 6-bromo-3,3-dimethyl-1,3-dihydroindeno[2,1-b]carbazole, 4.9 g (24 mmole) of iodobenzene, 17.1 g (90 mmole) of copper(I)iodide, 18.9 g (90 mmole) of potassium phosphate, 10.2 g (90 mmole) of trans-1,2-cyclohexanediamine and 1,4-dioxane 300 ml were refluxed under nitrogen for about overnight. Then, the solution was filtered at 110 C. To receive the filtrate, And the 1,4-dioxane was removed under reduced pressure from the filtrate. The filtrate was extracted with 200 ml dichloromethane and 400 ml of water, the organic layer was dried with anhydrous magnesium sulfate, the solvent was removed and the residue was purified by column chromatography on silica gel (hexane-ethyl acetate) to give product 6.8 g (71%). 1NMR(CDCl3, 400 MHz): chemical shift (ppm) 8.568.23 (m, 3H), 7.918.81 (m, 2H), 7.777.75 (m, 4H), 7.527.28 (m, 5H), 1.66 (s, 6H).

Synthesis of 3,3-dimethyl-1-phenyl-6-(pyridin-2-yl)-1,3-dihydroindeno[2,1-b]carbazole

(26) ##STR00020##

(27) A mixture of 6.8 g (15.5 mmol) of 6-bromo-3,3-dimethyl-1-phenyl-1,3-dihydroindeno[2,1-b]carbazole, 3.3 g (21 mmol) of pyridin-2-ylboronic acid, 0.44 g (0.4 mmol) of tetrakis(triphenylphosphine) palladium, 30 ml of 2M Na.sub.2CO.sub.3, 40 ml of EtOH and 80 ml toluene was degassed and placed under nitrogen, and then heated at 90 C. overnight. After finishing the reaction, the mixture was allowed to cool to room temperature. The solution was extracted with 250 ml of ethyl acetate and 1000 ml of water. The organic layer was dried with anhydrous magnesium sulfate and the solvent was evaporated under reduced pressure. The residue was purified by column chromatography on silica (HxEA) to give product 5.3 g (78%).

(28) Synthesis of Dichloro-Bridged Dimer

(29) ##STR00021##

(30) A mixture of 7.35 g (20 mmol) of iridium(III)chloride, 13 g (85 mmol) of 2-phenylpyridine, 120 ml of 2-methoxyethanol and 30 ml of distilled water, was placed under nitrogen, and then heated reflux overnight. After finishing the reaction, the mixture was allowed to cool to room temperature. The yellow precipitate formed was vacuum filtered and washed with ethanol and hexanes. The dichloro-bridged dimer was dried in a vacuum oven to give 1.0 g. The product was not purified any further but used directly in the next step.

(31) Synthesis of Iridium Triflate Precursor

(32) ##STR00022##

(33) A mixture of 9.6 g of dichloro-bridged dimer, 4.6 g (17.5 mmol) of silver triflate, 300 ml of dichloromethane and 5 ml of methanol, was placed under nitrogen, and then stirred overnight. After finishing the reaction, the silver chloride was filtered off. The solvent was evaporated. 10.6 g of product was obtained. The product was not purified any further but used directly in the next step.

Synthesis of Example 11

(34) ##STR00023##

(35) A mixture of 4.7 g (6 mmol) of iridium triflate precursor, 5.3 g (12.1 mmol) of 3,3-dimethyl-1-phenyl-6-(pyridin-2-yl)-1,3-dihydroindeno[2,1-b]carbazole, 60 ml of EtOH and 15 ml of MeOH, was placed under nitrogen, and then heated reflux overnight. After finishing the reaction, the mixture was allowed to cool to room temperature. The yellow precipitate formed was vacuum filtered and washed with ethanol and hexanes, the product was purified by vacuum sublimation to give 2.1 g of yellow product. MS (m/z, FAB.sup.+): 936.4; 1H NMR (CDCl.sub.3, 500 MHz): chemical shift (ppm) 8.93 (s, 1H), 8.648.61 (m, 5H), 8.177.9 (m, 4H), 7.837.50 (m, 13H), 7.447.15 (m, 8H), 6.946.89 (m, 2H), 1.65 (s, 6H).

GENERAL METHOD OF PRODUCING ORGANIC EL DEVICE

(36) ITO-coated glasses with 912 ohm/square in resistance and 120160 nm in thickness are provided (hereinafter ITO substrate) and cleaned in a number of cleaning steps in an ultrasonic bath (e.g. detergent, deionized water). Before vapor deposition of the organic layers, cleaned ITO substrates are further treated by UV and ozone. All pre-treatment processes for ITO substrate are under clean room (class 1000).

(37) These organic layers are applied onto the ITO substrate in order by vapor deposition in a high-vacuum unit (10.sup.7 Torr), such as: resistively heated quartz boats. The thickness of the respective layer and the vapor deposition rate (0.10.3 nm/sec) are precisely monitored or set with the aid of a quartz-crystal monitor. It is also possible, as described above, for individual layers to consist of more than one compound, i.e. in general a host material doped with a dopant material. This is achieved by co-vaporization from two or more sources.

(38) Dipyrazino[2,3-f: 2,3-]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) is used as hole injection layer in this organic EL device, and N,N-Bis (naphthalene-1-yl)-N,N-bis(phenyl)-benzidine (NPB) is most widely used as the hole transporting layer, N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-phenylbiphenyl-4-yl)-9H-fluoren-2-amine (EB2) is used as electron blocking layer, and the chemical structure shown below:

(39) ##STR00024##

(40) In the present invention the phosphorescent emitting host used as the following formulas:

(41) ##STR00025##
wherein X is a divalent bridge selected from the atom or group consisting from O, S, C(R.sub.8).sub.2, N(R.sub.9) and Si(R.sub.10).sub.2, m represents an integer of 0 to 4, n represents an integer of 0 to 8, R.sub.1 to R.sub.4 and R.sub.8 to R.sub.10 are independently selected from the group consisting of a hydrogen atom, a halide, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms; wherein the preferably phosphorescent light emitting host is selected from the group consisting of:

(42) ##STR00026## ##STR00027##

(43) Organic iridium complexes are widely used as phosphorescent guest for light emitting layer, Ir(ppy).sub.3 is widely used for phosphorescent green guest of light emitting layer for comparable materials in the present invention.

(44) ##STR00028##

(45) HB3 (see the following chemical structure) is used as hole blocking material (HBM) and 2-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-12-yl)-4,6-diphenyl-1,3,5-triazine (ET2) is used as electron transporting material to co-deposit with 8-hydroxyquinolato-lithium (LiQ) in organic EL device. The prior art of other OLED materials for producing standard organic EL device control and comparable material in this invention shown its chemical structure as follows:

(46) ##STR00029##

(47) A typical organic EL device consists of low work function metals, such as Al, Mg, Ca, Li and K, as the cathode by thermal evaporation, and the low work function metals can help electrons injecting the electron transporting layer from cathode. In addition, for reducing the electron injection barrier and improving the organic EL device performance, a thin-film electron injecting layer is introduced between the cathode and the electron transporting layer. Conventional materials of electron injecting layer are metal halide or metal oxide with low work function, such as: LiF, LiQ, MgO, or Li.sub.2O. On the other hand, after the organic EL device fabrication, EL spectra and CIE coordination are measured by using a PR650 spectra scan spectrometer. Furthermore, the current/voltage, luminescence/voltage and yield/voltage characteristics are taken with a Keithley 2400 programmable voltage-current source. The above-mentioned apparatuses are operated at room temperature (about 25 C.) and under atmospheric pressure.

EXAMPLE 2

(48) Using a procedure analogous to the above mentioned general method, phosphorescent emitting organic EL device having the following device structure was produced (See FIG. 1). Device: ITO/HAT-CN(20 nm)/NPB (110 nm)/EB2(5 nm)/Emitting host doped 12% phosphorescent emitting guest (30 nm)/HB3(10 nm)/ET2 doped 40% LiQ (35 nm)/LiQ (1 nm)/Al (160 nm). The I-V-B (at 1000 nits) and half-life time of phosphorescent emitting organic EL device testing report as Table 1. The half-life time is defined that the initial luminance of 1000 cd/m.sup.2 has dropped to half.

(49) TABLE-US-00001 TABLE 1 Emitting Emitting Voltage Efficiency Half-life host guest (V) (cd/A) Color time (hour) H1 EX11 3.6 45 green 1380 H2 Ir(ppy).sub.3 4.1 44 green 960 H2 EX11 3.3 48 green 1250 H3 EX11 3.6 42 green 1150 H4 EX11 3.8 28 green 1100 H5 EX11 4.0 21 green 1050 H6 EX11 3.8 25 green 1010 H2 + H6 Ir(ppy).sub.3 3.5 54 green 1120 H2 + H6 EX11 3.2 56 green 1580

(50) In the above preferred embodiments for phosphorescent organic EL device test report (see Table 1), we show that the iridium complexes with a general formula (1) used as light emitting guest of emitting layer for organic EL device in the present invention display good performance than the prior art of organic EL materials. More specifically, the organic EL device in the present invention use the iridium complexes with a general formula (1) as light emitting guest material to collocate with emitting host material H1 to H6 shown lower power consumption, longer half-life time and higher efficiency.

(51) To sum up, the present invention discloses an iridium complexes which can be used as light emitting guest of emitting layer for organic EL device are disclosed. The mentioned the iridium complexes represented by the following formula (1):

(52) ##STR00030##
wherein m represents an integer of 1 or 2, X independently represents a divalent bridge selected from the atom or group consisting from O, S and N(R.sub.7), A ring represents a substituted or unsubstituted benzene ring, Y.sub.1 and Y.sub.2 are different and Y.sub.1, Y.sub.2 represent nitrogen or carbon atom; R.sub.1 to R.sub.7 are the same or different, R.sub.1 to R.sub.7 independently selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

(53) Obvious many modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the present invention can be practiced otherwise than as specifically described herein. Although specific embodiments have been illustrated and described herein, it is obvious to those skilled in the art that many modifications of the present invention may be made without departing from what is intended to be limited solely by the appended claims.