Method for preparing a series of carbazole derivatives and use thereof in organic light-emitting diodes

Abstract

Disclosed are a method for preparing a series of carbazole derivatives and use thereof in organic light-emitting diodes. The structure of the material is as shown in Formula I. An organic electroluminescent device prepared by the material can have a significantly improved power efficiency and an external quantum efficiency for the device and an extended life for an orange light or red light device; moreover, the material has characteristics, for example, methods for the synthesis and purification of the material are simple and suitable for large-scale production, and is an ideal choice as a luminescent material for organic electroluminescent devices. The use of the organic electroluminescent diode material as a carrier transport material or as a luminescent material alone or as a host material in a light-emitting layer also falls within the scope of protection. ##STR00001##

Claims

1. A compound selected from the group consisting of the following compounds: ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047## ##STR00048##

2. An organic electroluminescent device comprising a luminescent layer containing a compound of claim 1.

3. The organic electroluminescent device according to claim 2, wherein the organic electroluminescent device is composed of a transparent substrate, an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer and a cathode layer in sequence from the bottom to the top.

4. The organic electroluminescent device according to claim 3, wherein the material constituting said transparent substrate is glass or a flexible substrate; and the material constituting said anode layer is an inorganic material or an organic electrically conductive polymer; wherein said inorganic material is indium tin oxide, zinc oxide, tin zinc oxide, gold, silver or copper; and said organic electrically conductive polymer is selected from at least one of a polythiophene, sodium polyvinylbenzene sulphonate and a polyaniline.

5. The device according to claim 4, wherein said hole injection layer contains one or more of the following compounds: ##STR00049## ##STR00050## said hole transport layer contains one or more of the following compounds: ##STR00051## the material constituting said organic light-emitting layer further comprises one or more of the following materials: ##STR00052## ##STR00053## ##STR00054## the material constituting said electron transport layer is Liq, Gaq3, TPBI or Slichem-EL-068, the structures being as follows: ##STR00055## and the material constituting said cathode layer is selected from any one of or an alloy of any two of or a fluoride of the following elements: lithium, magnesium, silver, calcium, strontium, aluminium, indium, copper, gold and silver.

6. The device according to claim 4, wherein the thickness of said hole injection layer is 30-50 nm; the thickness of said hole transport layer is 5-15 nm; the thickness of said organic light-emitting layer is 10-100 nm; the thickness of said electron transport layer is 10-50 nm; and the thickness of said cathode layer is 90-110 nm.

7. The device according to claim 4, wherein the thickness of said hole injection layer is 40 nm; the thickness of said hole transport layer is 10 nm; the thickness of said organic light-emitting layer is 20 nm; the thickness of said electron transport layer is 40 nm; and the thickness of said cathode layer is 100 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The technical solutions and other advantageous effects of the present invention will be apparent from the following detailed description of the specific examples of the invention in conjunction with the accompanying drawings.

(2) In the drawings,

(3) FIG. 1 is a flow chart of a method for preparing a series of carbazole derivatives of the present invention;

(4) FIG. 2 is a schematic structural diagram of an OLED device structure manufactured by using a compound of Formula (1) of the present invention;

(5) FIG. 3 is an ultraviolet absorption spectrum of a compound of formula (A21) of the present invention;

(6) FIG. 4 is a fluorescence spectrum of the compound of formula (A21) of the present invention;

(7) FIG. 5 is an ultraviolet absorption spectrum of a compound of formula (A30) of the present invention; and

(8) FIG. 6 is a fluorescence spectrum of the compound of formula (A30) of the present invention.

PARTICULAR EMBODIMENTS

(9) The present invention is further illustrated by the specific examples below, but is not limited to these specific examples.

Example 1: Preparation of Compound A11

Step I: Preparation of Intermediate Benzothiadiazole

(10) 10.0 g (92.5 mmol) of o-phenylenediamine is mixed with 300 ml of dichloromethane, 37.4 g (370 mmol) of triethylamine is added and dissolved with stirring, 13.6 ml (184.9 mmol) of thionyl chloride is dropwise added slowly, after being heated to reflux for a reaction for 5 hours, the material is cooled to room temperature and concentrated to dryness under a reduced pressure, 700 ml of water is added, concentrated hydrochloric acid is dropwise added to adjust the pH to acidic, and after filtration, the filter cake is recrystallized with ethanol to give 11 g of a yellow solid, with a yield of 88%.

Step II: Preparation of Intermediate 4,7-Dibromobenzothiadiazole

(11) 10 g (73.4 mmol) of the intermediate from the last step is mixed with 100 ml of 48% hydrobromic acid, 35 g (22.3 mmol) of bromine is dropwise added at room temperature, after being heated to reflux for a reaction for 5 hours, the material is cooled to room temperature, 100 ml of a saturated aqueous solution of sodium bisulphite is added, and after filtration, the filter cake is recrystallized with ethanol to give 20.7 g of a yellow solid, with a yield of 96%.

Step III: Preparation of Compound A2

(12) 5 g (17.0 mmol) of 4,7-dibromobenzothiadiazole is mixed with 2.8 g (16.8 mmol) of 3-(N,N-diphenyl)aminocarbazole, 324 mg (1.7 mmol) of cuprous iodide and 9.4 g (68 mmol) of potassium carbonate are added, 100 ml of xylene is added, 399 mg (3.4 mmol) of L-proline is added, after being heated to reflux with stirring for a reaction for 12 hours, the material is cooled to room temperature and filtered, the filter cake is washed with toluene, the filtrate is concentrated to dryness under a reduced pressure, 100 ml of anhydrous ethanol is added, and the material is heated to boiling and filtered immediately when hot to give 8.4 g of a yellow solid, with a yield of 62%. MS (MALDI-TOF): m/z 801.273 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.055-7.358 (28H, m), 7.563-7.584 (2H, m), 7.624-7.638 (2H, m), 7.644-7.662 (2H, m), 8.324-8.341 (2H, m).

Step IV: Preparation of Intermediate 3,6-bis(3-diphenylamino)carbazole)benzene-1,2-diamine

(13) 5 g (6.2 mmol) of a compound A2 is mixed with 725 mg (18.7 mmol) of sodium borohydride, 100 ml of tetrahydrofuran and 10 ml of water are added, after being heated to reflux with stirring for a reaction for 12 hours, the material is cooled to room temperature and concentrated to dryness under a reduced pressure, 100 ml of water is added, and the material is filtered to give 4.6 g of a yellow solid, with a yield of 95%.

Step V: Preparation of Compound A11

(14) 4 g (5.1 mmol) of the diamine intermediate prepared above is mixed with 750 mg (5.1 mmol) of a 40% an aqueous solution of glyoxal, 50 ml of tetrahydrofuran is added, after heating to reflux with stirring, 0.1 ml of concentrated hydrochloric acid is added, after a reflux reaction for 4 hours, the material is cooled to room temperature and concentrated to dryness under a reduced pressure, 50 ml of water is added, and the material is filtered to give 2.8 g of a yellow solid, with a yield of 68%. MS (MALDI-TOF): m/z 794.323 [M].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.054-7.353 (28H, m), 7.561-7.582 (2H, m), 7.623-7.637 (2H, m), 7.643-7.661 (2H, m), 8.322-8.339 (2H, m), 8.852 (2H, s).

Example 2: Preparation of Compound A21

Step I: Preparation of Compound A3

(15) The synthesis operation is carried out with reference to Step III in Example 1, with 3-(N,N-diphenyl)aminocarbazole in Step III in Example 1 replaced with 3-carbazolylcarbazole, to give a yellow solid, with a yield of 55%. MS (MALDI-TOF): m/z 797.244 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.153-7.448 (16H, m), 7.562-7.585 (4H, m), 7.664-7.692 (6H, m), 7.847-7.865 (2H, m), 8.124-8.146 (4H, m).

Step II: Intermediate 3,6-bis(9H-[3,9-dicarbazole]-9-yl)benzene-1,2-diamine

(16) The synthesis operation is carried out with reference to Step IV in Example 1, with A2 in Step IV in Example 1 replaced with A3, to give a yellow solid, with a yield of 95%.

Step III: Preparation of Compound A21

(17) 5 g (6.5 mmol) of the diamine intermediate prepared above is mixed with 1.3 g (6.2 mmol) of phenanthrenequinone, 50 ml of glacial acetic acid is added, after being heated to reflux with stirring for a reaction for 6 hours, the material is cooled to 60 C. and filtered, and the filter cake is washed with acetic acid and then washed with water and ethanol to give 5 g of a yellow solid, with a yield of 81.7%.

(18) MS (MALDI-TOF): m/z 941.322 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.155-7.252 (12H, m), 7.465-7.626 (14H, m), 7.846-7.869 (4H, m), 7.882-7.905 (4H, m), 8.123-8.145 (4H, m), 9.121-9.133 (2H, m).

Example 3: Preparation of Compound of Formula A40

Step I: Preparation of Intermediate 1-(4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)indole-2,3-dione

(19) 10 g (0.068 mol) of isatin is mixed with 100 ml of N,N-dimethylformamide, 18.8 g (0.136 mol) of potassium carbonate and 1.3 g (6.8 mmol) of cuprous iodide are added, 2 g (17 mmol) of L-proline and 29.6 g (0.075 mol) of 2-(4-iodophenyl)-1-phenyl-1H-benzo[d]imidazole are further added, under the protection of nitrogen, the material is heated to 150 C. with stirring and reacted for 12 hours, cooled to room temperature and filtered, the filtrate is poured into 500 ml of ice water and filtered, and the filter cake is washed with water and then with ethanol to give 16 g of a brown solid, with a yield of 58%.

Step II: Preparation of Compound A40

(20) 10.5 g (24 mmol) of 3,6-dicarbazolyl-1,2-diaminobenzene intermediate is mixed with 10 g (24 mmol) of the intermediate from the last step, 150 ml of acetic acid is added, after being heated to reflux with stirring for a reaction for 8 hours, the material is cooled to room temperature and filtered, and the filter cake is washed with water and then ethanol to give 11 g of a yellow solid, with a yield of 56%. MS (MALDI-TOF): m/z 818.294 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.253-7.528 (21H, m), 7.535-7.641 (8H, m), 7.816-7.824 (2H, m), 8.246-8.259 (3H, m), 8.6467.655 (1H, m).

Example 4: Preparation of Compound A52

(21) 10 g (22.8 mmol) of a 3,6-dicarbazolyl-1,2-diaminobenzene intermediate is mixed with 2.3 g (7.6 mmol) of hexaketocyclohexane octahydrate, 200 ml of acetic acid is added, 0.5 g of p-toluenesulphonic acid is added, after being heated to reflux with stirring for a reaction for 12 hours, the material is cooled to room temperature and filtered, and the filter cake is washed with water and then ethanol to give 8.3 g of a brown solid, with a yield of 82%. MS (MALDI-TOF): m/z 1374.460 [M].sup.+. .sup.1H-NMR (, DMSO-d.sub.6): 7.155-7.468 (36H, m), 7.822-7.840 (6H, m), 7.865-7.884 (6H, m), 8.122-8.139 (6H, m).

Example 5: Preparation of Compound A77

Step I: Preparation of Intermediate 4,4-dicarbazolylbenzil

(22) 4 g (10.8 mmol) of 4,4-dibromobenzil is dispersed in 80 ml of nitrobenzene, 4 g (24 mmol) of carbazole, 419 mg (2.2 mmol) of cuprous iodide, 4.5 g (32 mmol) of potassium carbonate and 1.1 g of 18-crown-6 are added, under the protection of nitrogen, the material is heated to reflux and reacted for 8 hours, cooled to room temperature and filtered, and the filtrate is concentrated to dryness under a reduced pressure and separated and purified with a silica gel column to give 4.6 g of a yellow solid, with a yield of 78%.

Step II: Preparation of Compound A72

(23) 3.5 g (7.4 mmol) of a 3,6-dicarbazolyl-1,2-diaminobenzene intermediate is mixed with 4 g (7.4 mmol) of the intermediate from the last step, 80 ml of glacial acetic acid is added, after being heated to reflux with stirring for a reaction for 12 hours, the material is cooled to room temperature and filtered, and the filter cake is washed with water and then ethanol to give 6.4 g of a yellow solid, with a yield of 92%. MS (MALDI-TOF): m/z 943.352 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.155-7.293 (12H, m), 7.324-7.396 (10H, m), 7.724-7.792 (12H, m), 7.816-7.827 (4H, m), 8.116-8.131 (4H, m).

Step III: Preparation of Compound A77

(24) 6.0 g (6.36 mmol) of a compound A72 is dissolved in 600 ml of anhydrous dichloromethane, under the protection of nitrogen, 10.3 g (63.6 mmol) of anhydrous ferric chloride is added, after a reaction with stirring at room temperature for 6 hours, the material is concentrated to dryness under a reduced pressure, 100 ml of anhydrous methanol is added, and the material is heated to boiling and filtered immediately when hot to give a grey solid, and then separated and purified with a silica gel column to give 3.3 g of a yellow solid, with a yield of 55%. MS (MALDI-TOF): m/z 941.343 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.156-7.294 (12H, m), 7.325-7.397 (10H, m), 7.627-7.642 (6H, m), 7.662-7.679 (6H, m), 7.806-7.810 (4H, m), 8.546 (2H, s).

Example 6: Preparation of Compound A82

Step I: Preparation of Intermediate 4-(4,7-bis(9H-carbazol-9-yl)-1H-benzo[d]imidazol-2-yl)-N,N-diphenylamine

(25) 4.4 g (10 mmol) of a 3,6-dicarbazolyl-1,2-diaminobenzene intermediate is mixed with 2.8 g (10 mmol) of 4-dianilinobenzaldehyde, 50 ml of N,N-dimethylformamide is added, the material is heated to 150 C. with stirring and reacted for 8 hours and cooled to room temperature, the reaction solution is poured into ice water and filtered, the filter cake is washed with water and then ethanol to give 6 g of a yellow solid, with a yield of 88%.

Step II: Preparation of Compound A82

(26) 5 g (7.2 mmol) of the intermediate from the last step is mixed with 1.77 g (8.6 mmol) of iodobenzene, 80 ml of N,N-dimethylformamide is added, 138 mg (0.72 mmol) of cuprous iodide and 344 mg (8.6 mmol) of sodium hydroxide are further added, the material is heated to reflux with stirring and reacted for 2 hours and cooled to room temperature, the reaction solution is poured into ice water and filtered, the filter cake is washed with water and then ethanol to give 4.8 g of a yellow solid, with a yield of 87%. MS (MALDI-TOF): m/z 768.312 [M+1].sup.+. .sup.1H-NMR (, CDCl.sub.3): 7.032-7.163 (14H, m), 7.206-7.468 (15H, m), 7.736-7.776 (4H, m), 7.884-7.904 (2H, m), 8.279-8.297 (2H, m).

Example 7: Preparation of OLED-1 to OLED-3

(27) 1) A glass substrate on which an ITO conductive layer is sputtered is subjected to an ultrasonic treatment in a cleaning agent for 30 minutes, rinsed in deionized water, subjected to a ultrasonic treatment in an acetone/ethanol mixed solvent for 30 minutes, baked in a clean environment to completely dryness and irradiated with an ultraviolet light cleaner for 10 minutes, and the surface is bombarded with low energy cations;

(28) 2) the above-treated ITO glass substrate is placed in a vacuum chamber, the vacuum chamber is evacuated to 110.sup.5 Pa to 910.sup.3 Pa, and a compound HATCN is evaporated as a hole injection layer onto the above-mentioned anode layer film, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 40 nm;

(29) 3) on the above-mentioned hole injection layer, NPB is further evaporated as a hole transport layer, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 10 nm;

(30) 4) on the hole transport layer, an organic light-emitting layer of the device with DPEPO as a host material and a compound (of Formula I) of the present invention as a doping material, with DPEPO: the compound of Formula I=90:10 is further evaporated, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated organic light-emitting layer film being 20 nm;

(31) 5) on the organic light-emitting layer, a layer of Liq as an electron transport layer of the device is further evaporated, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 40 nm; and

(32) 6) on the electron transport layer, a magnesium/silver alloy layer as a cathode layer of the device is evaporated in turn to give an OLED device provided by the present invention, wherein the evaporation rate for the magnesium/silver alloy layer is 2.0-3.0 nm/s, the thickness of the evaporated film is 100 nm, and the mass ratio of magnesium to silver is 1:9.

(33) According to the same procedure as above, as the compound (of Formula I) in Step 4), a compound A21 is selected to give OLED-1 provided by the present invention;

(34) according to the same procedure as above, as the compound (of Formula I) in Step 4), a compound A82 is selected to give OLED-2 provided by the present invention; and

(35) according to the same procedure as above, the compound (of Formula I) in Step 4) is replaced with DMAC-DPS to give a comparative device OLED-3;

(36) ##STR00030##

(37) and the performance test results of the resulting devices OLED-1 to OLED-3 are as shown in Table 1.

(38) TABLE-US-00001 TABLE 1 Performance test results of the resulting devices OLED-1 to OLED-3 Doping Electric material Turn-on current Device Compound voltage density Brightness EQE CIE T.sub.95 No. formula (V) (mA/cm.sup.2) (Cd/m.sup.2) (%) (x, y) (hour) OLED-1 A21 3.8 3.2 1000 17.5 0.44, 4500 0.50 OLED-2 A82 3.6 2.8 1000 18.6 0.24, 5000 0.66 OLED-3 DMAC-DPS 3.8 3.5 1000 17.0 0.16, 3000 0.20

(39) As can be seen from above, the devices prepared by the organic materials of the present patent invention have a low turn-on voltage, under the same brightness conditions, the external quantum efficiencies of the devices are obviously higher than that of the comparative device OLED-3 with DMAC-DPS as the doping material, and the lives of the devices are much longer.

Example 8: Preparation of OLED-4 to OLED-6

(40) 1) A glass substrate on which an ITO conductive layer is sputtered is subjected to an ultrasonic treatment in a cleaning agent for 30 minutes, rinsed in deionized water, subjected to a ultrasonic treatment in an acetone/ethanol mixed solvent for 30 minutes, baked in a clean environment to completely dryness and irradiated with an ultraviolet light cleaner for 10 minutes, and the surface is bombarded with low energy cations;

(41) 2) the above-treated ITO glass substrate is placed in a vacuum chamber, the vacuum chamber is evacuated to 110.sup.5 Pa to 910.sup.3 Pa, and a compound HATCN is evaporated as a hole injection layer onto the above-mentioned anode layer film, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 40 nm;

(42) 3) on the above-mentioned hole injection layer, NPB is further evaporated as a hole transport layer, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 10 nm;

(43) 4) on the hole transport layer, an organic light-emitting layer of the device with a compound (of Formula I) of the present invention as a host material and Ir(CHPIQ).sub.2acac as a doping material, with the compound of Formula I: Ir(CHPIQ).sub.2acac=90:10 is further evaporated, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated organic light-emitting layer film being 20 nm;

(44) 5) on the organic light-emitting layer, a layer of Liq as an electron transport layer of the device is further evaporated, with the evaporation rate being 0.1 nm/s and the thickness of the evaporated film being 40 nm; and

(45) 6) on the electron transport layer, a magnesium/silver alloy layer as a cathode layer of the device is evaporated in turn to give an OLED device provided by the present invention, wherein the evaporation rate for the magnesium/silver alloy layer is 2.0-3.0 nm/s, the thickness of the evaporated film is 100 nm, and the mass ratio of magnesium to silver is 1:9.

(46) According to the same procedure as above, as the compound (of Formula I) in Step 4), a compound A30 is selected to give OLED-4 provided by the present invention;

(47) according to the same procedure as above, as the compound (of Formula I) in Step 4), a compound A57 is selected to give OLED-5 provided by the present invention; and

(48) according to the same procedure as above, the compound (of Formula I) in Step 4) is replaced with PPQ-BCZ to give a comparative device OLED-6;

(49) ##STR00031##

(50) and the performance test results of the resulting devices OLED-4 to OLED-6 are as shown in Table 2.

(51) TABLE-US-00002 TABLE 2 Performance test results of the resulting devices OLED-4 to OLED-6 Host Electric material Turn-on current DEVICES Compound voltage density Brightness EQE CIE T.sub.95 No. formula (V) (mA/cm.sup.2) (Cd/m.sup.2) (%) (x, y) (hour) OLED-4 A30 3.8 3.6 1000 21.4 0.67, 5000 0.32 OLED-5 A57 3.6 3.4 1000 21.6 0.67, 6000 0.31 OLED-6 PPQ-BCZ 4.4 3.8 1000 20.0 0.68, 5000 0.32

(52) As can be seen from above, the devices prepared by the organic materials of the present patent invention have a low turn-on voltage, under the same brightness conditions, the external quantum efficiencies of the devices are obviously higher than that of the comparative device OLED-6 with PPQ-BCZ as the host material, and the lives of the devices are much longer.

(53) Although the present invention has been described in conjunction with the preferred examples, the present invention is not limited to the above-described examples and drawings; and it is to be understood that under the guidance of the inventive concept, various modifications and improvements can be made by a person skilled in the art, and that the scope of the invention is embraced in the appended claims summarize.