Organic electroluminescence device and ink composition

Abstract

An organic electroluminescence device including: an anode and a cathode; and at least one organic thin film layer between the anode and the cathode, wherein one of the organic thin film layer(s) comprises a polymer represented by the following formula (1). ##STR00001##

Claims

1. An organic electroluminescence device comprising: an anode and a cathode; and at least one organic thin film layer between the anode and the cathode, wherein one of the organic thin film layer(s) comprises a polymer represented by the following formula (2): ##STR00070## wherein in the formula (2), R.sub.1 and R.sub.2 are independently a hydrogen atom, an alkyl group including 1 to 8 carbon atoms, a cycloalkyl group including 5 to 6 carbon atoms, an alkoxy group including 1 to 8 carbon atoms, an aryl group including 6 to 10 ring carbon atoms, an aryloxy group including 6 to 10 ring carbon atoms, a fluorine atom, a chlorine atom, an alkoxyalkyl group including 2 to 16 carbon atoms, a substituted or unsubstituted amino group or a substituted or unsubstituted mercapto group; R.sub.1 and R.sub.2 may independently be bonded to another atom to form a ring or may be bonded to each other to form a ring; X.sub.1 is —O— or —S—; R.sub.3 is an alkyl group including 1 to 8 carbon atoms, a substituted or unsubstituted alkoxy group including 1 to 8 carbon atoms, a substituted or unsubstituted alkyl carbonyl group including 1 to 8 carbon atoms, a substituted or unsubstituted aryl group including 6 to 10 carbon atoms, a substituted or unsubstituted aryloxy group including 6 to 10 carbon atoms, a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms or a substituted or unsubstituted aralkyl group including 7 to 20 carbon atoms; R.sub.4 is a hydrogen atom, an alkyl group including 1 to 8 carbon atoms, a substituted or unsubstituted alkoxy group including 1 to 8 carbon atoms, a substituted or unsubstituted alkyl carbonyl group including 1 to 8 carbon atoms, a substituted or unsubstituted aryl group including 6 to 10 carbon atoms, a substituted or unsubstituted aryloxy group including 6 to 10 carbon atoms, a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms or a substituted or unsubstituted aralkyl group including 7 to 20 carbon atoms; n is an integer of 10 to 3000; L.sub.1 is a single bond or a group represented by the following formula (2′) or the following formula (3′);
-L.sub.11-L.sub.12-L.sub.13-  (2′) wherein in the formula (2′), L.sub.11 is an alkylene group including 1 to 8 carbon atoms; L.sub.12 is a single bond, —O— or —S— and L.sub.13 is a single bond or an alkylene group including 1 to 8 carbon atoms; and L.sub.11 is bonded to R.sub.4;
-L.sub.14-L.sub.15-B-L.sub.16-(3′) wherein in the formula (3′), L.sub.14 is a single bond or an alkylene group including 1 to 8 carbon atoms; L.sub.15 is a single bond, —O— or —S—, B is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring; L.sub.16 is a single bond, —O— or —S—, and L.sub.14 is bonded to R.sub.4.

2. The organic electroluminescence device according to claim 1, wherein R.sub.4 is an alkyl group including 1 to 8 carbon atoms, a substituted or unsubstituted alkoxy group including 1 to 8 carbon atoms, a substituted or unsubstituted alkyl carbonyl group including 1 to 8 carbon atoms, a substituted or unsubstituted aryl group including 6 to 10 carbon atoms, a substituted or unsubstituted aryloxy group including 6 to 10 carbon atoms, a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms or a substituted or unsubstituted aralkyl group including 7 to 20 carbon atoms.

3. The organic electroluminescence device according to claim 1, wherein R.sub.3 and R.sub.4 are independently a substituted or unsubstituted aryl group including 6 to 10 carbon atoms or a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms.

4. The organic electroluminescence device according to claim 1, wherein R.sub.1 and R.sub.2 are independently a hydrogen atom, an alkyl group including 1 to 8 carbon atoms, a cycloalkyl group including 5 to 6 carbon atoms, an alkoxy group including 1 to 8 carbon atoms, an aryl group including 6 to 10 ring carbon atoms, an aryloxy group including 6 to 10 ring carbon atoms or an alkoxyalkyl group including 2 to 16 carbon atoms.

5. The organic electroluminescence device according to claim 1, wherein R.sub.1 and R.sub.2 are independently an alkyl group including 1 to 8 carbon atoms, an alkoxy group including 1 to 8 carbon atoms or an aryl group including 6 to 10 ring carbon atoms.

6. The organic electroluminescence device according to claim 1, wherein X.sub.1 is —O—.

7. The organic electroluminescence device according to claim 1, wherein L.sub.1 is a single bond.

8. The organic electroluminescence device according to claim 1, wherein a polymer represented by the formula (2) is a polymer represented by the following formula (3): ##STR00071## wherein in the formula (3), R.sub.1 to R.sub.4 and n are as defined for R.sub.1 to R.sub.4 and n in the formula (2).

9. The organic electroluminescence device according to claim 1, wherein the polymer represented by the formula (2) is a polymer represented by the following formula (4): ##STR00072## wherein in the formula (4), R.sub.1, R.sub.2 and n are as defined for R.sub.1, R.sub.2 and n in the formula (2); and Ar.sub.3 and Ar.sub.4 are independently an aryl group including 6 to 10 ring carbon atoms.

10. The organic electroluminescence device according to claim 1, wherein the layer comprising the polymer represented by the formula (2) is an emitting layer.

11. The organic electroluminescence device according to claim 1, wherein the layer comprising the polymer represented by the formula (2) comprises said polymer in an amount of 1 to 80 wt %.

12. An ink composition comprising the polymer represented by the following formula (2) and an organic semiconductor material; ##STR00073## wherein in the formula (2), R.sub.1 and R.sub.2 are independently a hydrogen atom, an alkyl group including 1 to 8 carbon atoms, a cycloalkyl group including 5 to 6 carbon atoms, an alkoxy group including 1 to 8 carbon atoms, an aryl group including 6 to 10 ring carbon atoms, an aryloxy group including 6 to 10 ring carbon atoms, a fluorine atom, a chlorine atom, an alkoxyalkyl group including 2 to 16 carbon atoms, a substituted or unsubstituted amino group or a substituted or unsubstituted mercapto group; R.sub.1 and R.sub.2 may independently be bonded to another atom to form a ring or may be bonded to each other to form a ring; X.sub.1 is —O— or —S—; R.sub.3 is an alkyl group including 1 to 8 carbon atoms, a substituted or unsubstituted alkoxy group including 1 to 8 carbon atoms, a substituted or unsubstituted alkyl carbonyl group including 1 to 8 carbon atoms, a substituted or unsubstituted aryl group including 6 to 10 carbon atoms, a substituted or unsubstituted aryloxy group including 6 to 10 carbon atoms, a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms or a substituted or unsubstituted aralkyl group including 7 to 20 carbon atoms; R.sub.4 is a hydrogen atom, an alkyl group including 1 to 8 carbon atoms, a substituted or unsubstituted alkoxy group including 1 to 8 carbon atoms, a substituted or unsubstituted alkyl carbonyl group including 1 to 8 carbon atoms, a substituted or unsubstituted aryl group including 6 to 10 carbon atoms, a substituted or unsubstituted aryloxy group including 6 to 10 carbon atoms, a substituted or unsubstituted arylcarbonyl group including 6 to 10 carbon atoms or a substituted or unsubstituted aralkyl group including 7 to 20 carbon atoms; n is an integer of 10 to 3000; L.sub.1 is a single bond or a group represented by the following formula (2′) or the following formula (3′);
-L.sub.11-L.sub.12-L.sub.13-  (2′) wherein in the formula (2′), L.sub.11 is an alkylene group including 1 to 8 carbon atoms; L.sub.12 is a single bond, —O— or —S— and L.sub.13 is a single bond or an alkylene group including 1 to 8 carbon atoms; and L.sub.11 is bonded to R.sub.4;
-L.sub.14-L.sub.15-B-L.sub.16-  (3′) wherein in the formula (3′), L.sub.14 is a single bond or an alkylene group including 1 to 8 carbon atoms; L.sub.15 is a single bond, —O— or —S—, B is a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring; L.sub.16 is a single bond, —O— or —S—, and L.sub.14 is bonded to R.sub.4.

13. The ink composition according to claim 12, wherein the organic semiconductor material is a material for an organic electroluminescence device.

14. The ink composition according to claim 12 that further comprises a solvent.

15. A method for producing an organic semiconductor device, wherein at least one layer of an organic semiconductor device is produced by a wet method by using the ink composition according to claim 12.

16. A display apparatus that is provided with the organic electroluminescence device according to claim 1.

17. The organic electroluminescence device according to claim 1, wherein B is a substituted or unsubstituted aromatic hydrocarbon ring containing 6 to 20 ring carbon atoms or a substituted or unsubstituted aromatic heterocyclic ring containing 5 to 20 ring atoms with 1 to 3 ring atoms selected from a nitrogen atom, an oxygen atom and a sulfur atom.

18. The ink composition according to claim 12, wherein B is a substituted or unsubstituted aromatic hydrocarbon ring containing 6 to 20 ring carbon atoms or a substituted or unsubstituted aromatic heterocyclic ring containing 5 to 20 ring atoms with 1 to 3 ring atoms selected from a nitrogen atom, an oxygen atom and a sulfur atom.

Description

EXAMPLES

Preparation Example 1 (Synthesis of 2,6-dimethylphenol (xylenol))

(1) After firing 10 g of iron oxide at 450° C. for 3 hours, the iron oxide as fired, 50 g of phenol, 200 g of methanol and 100 g of water were placed in an autoclave and reacted at 360° C. for 15 minutes. After completion of the reaction, the product was collected by filtration, and 100 g of decane was added thereto. The organic phase was separated and dried with sodium sulfate, and then, subjected to distillation (131-135° C./100 mmHg) to obtain 49.5 g of 2,6-xylenol.

(2) The measurement result of 400 MHz NMR indicated δ 2.2 ppm —CH.sub.3, δ 4.6 ppm —OH and δ 6.7-6.9 Ar—H, and it was found that the compound obtained was the above-captioned substance.

Preparation Example 2 (Polymerization of 2,6-dimethylphenol)

(3) In a 500 mL-flask equipped with a stirrer, a thermometer and an oxygen introduction tube, 12.0 g of 2,6-xylenol obtained in Preparation Example 1, 60 mL of toluene, 0.1 g of cuprous chloride and 10 mL of pyridine were placed and stirred at 30° C. for 120 minutes while introducing oxygen. After completion of the reaction, the reaction solution was poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate a polymer. The polymer was dissolved in toluene, again poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate a polymer. The polymer was dissolved in 500 mL of methylene chloride, and 120 mL of methanol was added thereto. Subsequently, the solution was heated at 60° C. and left at rest. After cooling, the polymer separated was subjected to reprecipitation with methanol to obtain 5.4 g of 2,6-dimethyl-1,4-phenylene ether (P1). As a result of GPC measurement, it was found that the Mw of this polymer in terms of polystyrene was 94000, and Mw/Mn=2.33.

Preparation Example 3 (Terminal Modification of poly2,6-dimethyl-1,4-phenylene ether)

(4) 3.0 g of poly2,6-dimethyl-1,4-phenylene ether obtained in Preparation Example 2 was dissolved in 30 mL of methylene chloride, and 1.0 g of triethylamine and 1.0 g of benzoyl chloride were added thereto, followed by stirring at room temperature for 1 hour. Deposited salt was separated by filtration, a polymer was precipitated with methanol, and then washed with methanol. 2.9 g of poly2,6-dimethyl-1,4-phenylene ether (PX1) modified in the terminal was obtained.

(5) It was found that a benzoyl group was introduced because new peaks were observed at δ 8.1 ppm, 7.7 ppm and 7.5 ppm, and no peak was observed at 4 to 5 ppm in the 400 MHz NMR measurement result.

Preparation Example 4 (Synthesis of 2,6-dimethoxyphenol)

(6) A flask was charged with 32 g of 1,2,3-trimethoxybenzene (product manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mL of chloroform and 44 g of iodide trimethylsilane, and stirred at room temperature for 48 hours. After the reaction, diethyl ether was added thereto, and the resultant solution was washed with water three times, followed by drying with magnesium sulfate, and diethyl ether was distilled to obtain a solid. The solid was subjected to recrystallization by using acetone to obtain 28 g of 2,6-dimethoxyphenol. The measurement result of 400 MHz NMR indicated δ 3.6 ppm —OCH3, δ 6.1 ppm —OH, δ 6.4-6.9 Ar—H, and it was found that the compound obtained was the above-captioned substance.

Preparation Example 5 (Polymerization of 2,6-dimethoxyphenol)

(7) In a 300 mL-flask equipped with a stirrer, a thermometer and an oxygen introduction tube, 5.0 g of 2,6-dimethoxyphenol obtained in Preparation Example 4, 30 mL of toluene, 0.1 g of cuprous chloride and 50 mL of pyridine were placed and stirred at 30° C. for 6 hours while introducing oxygen. After completion of the reaction, the reaction solution was poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate a polymer. The polymer was dissolved in toluene, and again poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate the polymer. The polymer was dissolved in 300 mL of methylene chloride, and 60 mL of methanol was added thereto. Then, the solution was heated at 60° C. and left at rest. After cooling, the polymer separated was subjected to reprecipitation with methanol to obtain 3.1 g of poly2,6-dimethoxy-1,4-phenylene ether (P2). As a result of GPC measurement, it was found that the Mw of this polymer in terms of polystyrene was 22000, and Mw/Mn=2.82.

Preparation Example 6 (Terminal Modification of poly2,6-dimethoxy-1,4-phenylene ether)

(8) 3.0 g of poly2,6-dimethoxy-1,4-phenylene ether obtained in Preparation Example 5 was dissolved in 30 mL of methylene chloride, 1.0 g of triethylamine and 1.0 g of benzoylchloride were added thereto and the mixture was stirred at room temperature for 1 hour. Deposited salt was separated by filtration, a polymer was precipitated with methanol and washed with methanol. 2.2 g of poly2,6-dimethoxy-1,4-phenylene ether (PX2) modified in the terminal was obtained.

(9) It was found that a benzoyl group was introduced because new peaks were observed at δ 8.1 ppm, 7.7 ppm and 7.5 ppm, and no peak was observed at 4 to 5 ppm in the 400 MHz NMR measurement result.

Preparation Example 7 (Synthesis of 2,6-diphenylphenol)

(10) 200 mL of cyclohexane was heated at 150° C. and stirred, and 5.0 g of potassium hydroxide was added thereto to carry out a reaction for 3 hours. After removal of KOH, 10 g of alumina containing 0.5% of platinum was added to the reaction solution and stirred with heat at 330° C. for 8 hours. After cooling, low-boiling point substances were removed by heating under reduced pressure, and recrystallization from toluene was carried out to obtain 11.5 g of 2,6-diphenylphenol (melting point: 103° C.).

(11) The measurement result of 400 MHz NMR indicated δ 5.4 ppm —OH and δ 7.1-7.5 Ar—H, and it was found that the compound obtained was the above-captioned substance.

Preparation Example 8 (Polymerization of 2,6-diphenylphenol)

(12) In a 300 mL-flask equipped with a stirrer, a thermometer and an oxygen introduction tube, 5.0 g of 2,6-diphenylphenol obtained in Preparation Example 7 (product manufactured by Tokyo Chemical Industry Co., Ltd.), 30 mL of toluene, 0.1 g of cuprous chloride and 50 mL of pyridine were placed and stirred at 30° C. for 6 hours while introducing oxygen. After completion of the reaction, the reaction solution was poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate a polymer. The polymer was dissolved in toluene and again poured into 1 L of methanol solution containing 5 g of hydrochloric acid to precipitate the polymer. The polymer was dissolved in 300 mL of methylene chloride, 60 mL of methanol was added thereto, and then, the solution was heated at 60° C. and left at rest. The polymer separated was subjected to reprecipitation with methanol to obtain 3.3 g of poly2,6-diphenyl-1,4-phenylene ether (P3). As a result of GPC measurement, it was found that the Mw of this polymer in terms of polystyrene was 34000, and Mw/Mn=2.11.

Preparation Example 9 (Terminal Modification of poly2,6-diphenyl-1,4-phenylene ether)

(13) 3.0 g of poly2,6-diphenyl-1,4-phenylene ether obtained in Preparation Example 8 was dissolved in 30 mL of methylene chloride, 1.0 g of triethylamine and 1.0 g of benzoyl chloride were added thereto, and the mixture was stirred at room temperature for one hour. Deposited salt was separated by filtration, the polymer was precipitated with methanol, and then washed with methanol. 2.2 g of poly2,6-diphenyl-1,4-phenylene ether (PX3) modified in the terminal was obtained. It was found that a benzoyl group was introduced because new peaks were observed at δ 8.1 ppm, 7.7 ppm and 7.5 ppm, and no peak was observed at 4 to 5 ppm in the 400 MHz NMR measurement result.

Example 1

(14) (Cleaning of Substrate)

(15) A glass substrate of 25 mm by 25 mm by 1.1 mm thick with an ITO transparent electrode (manufactured by GEOMATEC Co., Ltd.) was subjected to ultrasonic cleaning with isopropyl alcohol for 5 minutes, and then subjected to UV-ozone cleaning for 5 minutes.

(16) (Forming of Underlayer)

(17) As a hole-transporting layer, CLEVIOUS AI4083 (product name) (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)) manufactured by HERAEUS and is represented below was formed into a film in a thickness of 30 nm on the ITO substrate by the spin coating method. After the film formation, unnecessary portion was removed with acetone, followed by firing on a hot plate at 200° C. for 10 minutes to prepare an underlayer.

(18) ##STR00067##
(Formation of Emitting Layer)

(19) By the use of the below-mentioned Compound H-1 as a host material, the below-mentioned Compound D-1 as a dopant material, and Polymer PX1 obtained in Preparation Example 3, a 1.4 wt % toluene solution was prepared such that the weight ratio of Compound H-1:Compound D-1: Polymer PX1 became 70:20:10. The toluene solution was applied on the above-mentioned substrate with the underlayer to form a film in a thickness of 50 nm by the spin coating method. After the application, unnecessary portion was removed with toluene, and heated and dried on a hot plate at 150° C. to prepare a multi-layered substrate on which an emitting layer was formed. All the procedures for forming the emitting layer were carried out in a glove box under an atmosphere of nitrogen.

(20) ##STR00068##
(Deposition and Sealing)

(21) The multi-layered substrate was transferred into a deposition chamber, and the below-mentioned Compound ET-1 was deposited thereon in a thickness of 50 nm as an electron-transporting layer. Further, lithium fluoride and aluminum were sequentially deposited thereon in a thickness of 1 nm and 80 nm, respectively. After completion of all the deposition steps, sealing with a counter bored glass was conducted in a glove box under an atmosphere of nitrogen to fabricate an organic EL device.

(22) ##STR00069##
(Evaluation of Device)

(23) The resultant organic EL device was driven with a direct current in a voltage of 0 to 10 volt (in a unit of 0.1 volt) to emit light, the emission luminance was measured with a luminance meter, and a voltage at which light emission could be observed at 100 cd/m.sup.2 was determined.

(24) Further, a time when luminance decreased from the initial luminance of 1000 cd/m.sup.2 to 500 cd/m.sup.2 under constant current driving (luminance half time) was measured. Table 1 shows the results.

Example 2

(25) A device was fabricated and evaluated in the same manner as in Example 1 except that PX2 obtained in Preparation Example 6 was used as the polymer for fabrication of the device. Table 1 shows the results.

Example 3

(26) A device was fabricated and evaluated in the same manner as in Example 1 except that PX3 obtained in Preparation Example 9 was used as the polymer for fabrication of the device. Table 1 shows the results.

Comparative Example 1

(27) A device was fabricated and evaluated in the same manner as in Example 1 except that P1 obtained in Preparation Example 2 was used as the polymer for fabrication of the device. Table 1 shows the results.

(28) TABLE-US-00001 TABLE 1 Voltage at emission Luminance half time Example 1 5.4 V 120 hrs Example 2 6.2 V  98 hrs Example 3 5.8 V 101 hrs Comparative Example 1 5.8 V  1 hr

(29) Although only some exemplary embodiments and/or examples of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments and/or examples without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.

(30) The Japanese application specification claiming priority under the Paris Convention are incorporated herein by reference in its entirety.