Aromatic amine derivative, and organic electroluminescent element using same

Abstract

An aromatic amine derivative represented by formula (1): ##STR00001##
wherein R.sup.1, R.sup.2, R.sup.3, L, Ar.sup.1, Ar.sup.2, k, m, and n are the same as defined in the specification, is useful as a material for an organic EL device and realizes an organic EL device with a high efficiency and a long lifetime even when driving it at a low voltage.

Claims

1. An organic electroluminescence device, comprising, in the order listed: an anode; a first hole transporting layer; a second hole transporting layer; a light emitting layer; and a cathode; wherein at least one of the first hole transporting layer and second hole transporting layer comprises an aromatic amine derivative represented by formula (1): ##STR00163## wherein in formula (1): R.sup.1 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group; R.sup.2 and R.sup.3 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, k represents an integer of 1 to 5; m represents an integer of 1 to 4; n represents an integer of 1 to 3; when groups R.sup.1 exist, the groups R.sup.1 may be the same or different, when groups R.sup.2 exist, the groups R.sup.2 may be the same or different; and when groups R.sup.3 exist; the groups R.sup.3 may be the same or different; L represents a single bond or a divalent group represented by formula (16): ##STR00164## wherein in formula (16): R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group; m represents an integer of 1 to 4; and when groups R.sup.1 exist, the groups R.sup.1 may be the same or different; Ar.sup.1 represents a group represented by formula (30): ##STR00165## wherein in formula (30): R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group; m represents an integer of 1 to 4; when groups R.sup.1 exist, the groups R.sup.1 may be the same or different; and two R.sup.4 may be the same or different and each independently represents a methyl group or a phenyl group; Ar.sup.2 represents a group represented by formula (7): ##STR00166## wherein in formula (7): R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group; k represents an integer of 1 to 5; m represents an integer of 1 to 4; and when groups R.sup.1 exist, the groups R.sup.1 may be the same or different.

2. The organic electroluminescence device according to claim 1, wherein two R.sup.4 represent methyl groups.

3. The organic electroluminescence device according to claim 1, wherein one of two R.sup.4 represents a methyl group and the other represents a phenyl group.

4. The organic electroluminescence device according to claim 1, wherein two R.sup.4 represent phenyl groups.

5. The organic electroluminescence device according to claim 1, wherein Ar.sup.2 represents a group represented by formula (7-1) or (7-2): ##STR00167## wherein R.sup.1, k and m are as defined in formulae (7).

6. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (1) each independently represents a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a s-butyl group, a t-butyl group or a phenyl group.

7. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (30) represents a hydrogen atom or a phenyl group.

8. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (7) represents a hydrogen atom, a methyl group, a t-butyl group, or a phenyl group.

9. The organic electroluminescence device according to claim 1, wherein R.sup.1, R.sup.2 and R.sup.3 in formula (1) represent hydrogen atoms.

10. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (16) represents a hydrogen atoms.

11. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (30) represents a hydrogen atom.

12. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (7) represents a hydrogen atom.

13. The organic electroluminescence device according to claim 1, wherein R.sup.1, R.sup.2 and R.sup.3 in formula (1), R.sup.1 in formula (16), R.sup.1 in formula (30), and R.sup.1 in formula (7) represent hydrogen atoms.

14. The organic electroluminescence device according to claim 1, wherein the aromatic amine derivative is any one of the following compounds: ##STR00168## ##STR00169## ##STR00170## ##STR00171## ##STR00172## ##STR00173## ##STR00174## ##STR00175## ##STR00176## ##STR00177## ##STR00178## ##STR00179## ##STR00180## ##STR00181## ##STR00182##

15. The organic electroluminescence device according to claim 1, wherein the first hole transporting layer comprises the aromatic amine derivative.

16. The organic electroluminescence device according to claim 1, wherein R.sup.2 and R.sup.3 in formula (1) each independently represents a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a s-butyl group, or a t-butyl group.

17. The organic electroluminescence device according to claim 1, wherein R.sup.1 in formula (1) each independently represents a hydrogen atom or a phenyl group.

18. The organic electroluminescence device according to claim 1, wherein in (R.sup.1)m of formula (1): R.sup.1 represents a phenyl group and m represents 1; and wherein in (R.sup.1)n of formula (1): R.sup.1 represents a hydrogen atom and n represents 3.

Description

EXAMPLES

(1) The present invention will be described below in more detail with reference to the examples. However, it should be noted that the scope of the invention is not limited thereto.

(2) Intermediate Synthesis 1-1 (Synthesis of Intermediate 1-1)

(3) Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of 4-iodobromobenzene, 22.3 g (105.0 mmol) of dibenzofuran-4-boronic acid, and 2.31 g (2.00 mmol) of Pd[PPh.sub.3].sub.4, 150 ml of toluene, 150 ml of dimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution of Na.sub.2CO.sub.3 were added, and the resultant mixture was stirred for 10 h while refluxing under heating.

(4) After the reaction, the obtained mixture was cooled to room temperature and extracted with dichloromethane in a separatory funnel. The organic layer was dried over MgSO.sub.4, and then filtered and condensed. The condensate was purified by silica gel column chromatography to obtain 26.2 g of a white solid, which was identified as the intermediate 1-1 by FD-MS analysis (Field Desorption Mass Spectrometry Analysis) (yield: 81%).

(5) ##STR00126##
Intermediate Synthesis 1-2 (Synthesis of Intermediate 1-2)

(6) Under an argon atmosphere, into a mixture of 24.0 g (112.0 mmol) of 4′-bromoacetanilide, 28.6 g (135.0 mmol) of dibenzofuran-4-boronic acid, and 2.6 g (2.24 mmol) of Pd[PPh.sub.3].sub.4, 450 ml of toluene, 100 ml of dimethoxyethane, and 110 ml (220.0 mmol) of a 2 M aqueous solution of Na.sub.2CO.sub.3 were added, and the resultant mixture was stirred for 10 h while refluxing under heating.

(7) After the reaction, the obtained mixture was cooled to room temperature, and the precipitated crystal was collected by filtration. The collected crystal was dissolved in tetrahydrofuran and filtered through celite/silica gel. The filtrate was condensed under reduced pressure. The obtained residue was washed with methanol/hexane and dried to obtain 18.0 g of a white solid, which was identified as the intermediate 1-2 by FD-MS analysis (yield: 53%)

(8) ##STR00127##
Intermediate Synthesis 1-3 (Synthesis of Intermediate 1-3)

(9) Into 18.0 g (59.7 mmol) of the intermediate 1-2, 120 ml of xylene, 1200 ml of water, and 60 ml of ethanol were added, and the resultant mixture was stirred. After adding 20.0 g (360.0 mmol) of potassium hydroxide, the mixture was stirred for 10 h while refluxing under heating.

(10) After the reaction, the obtained mixture was cooled to room temperature and extracted with toluene in a separatory funnel. The organic layer was dried over MgSO.sub.4, and then filtered and condensed. The obtained residue was recrystallized from xylene. The crystal was collected by filtration and dried to obtain 14.7 g of a white solid, which was identified as the intermediate 1-3 by FD-MS analysis (yield: 95%).

(11) ##STR00128##
Intermediate Synthesis 1-4 (Synthesis of Intermediate 1-4)

(12) Under a nitrogen atmosphere, 150 g (0.89 mol) of dibenzofuran was dissolved in 1000 ml of acetic acid under heating. After further adding 188 g (1.18 mol) of bromine dropwise, the resultant mixture was stirred at room temperature for 20 h.

(13) The precipitated crystal was collected by filtration and washed successively with acetic acid and water. The recrystallization of the crude product from methanol was repeated several times to obtain 66.8 g of a white crystal, which was identified as the intermediate 1-4 by FD-MS analysis (yield: 30%).

(14) ##STR00129##
Intermediate Synthesis 1-5 (Synthesis of Intermediate 1-5)

(15) Under an argon atmosphere, into 24.7 g (100.0 mmol) of the intermediate 1-4, 400 ml of dry tetrahydrofuran was added and the resultant mixture was cooled to−40° C. Further, 63 ml (100.0 mmol) of a 1.6 M hexane solution of n-butyllithium was gradually added. The reaction solution was stirred for one hour while heating to 0° C. Then, the reaction solution was cooled again to −78° C. and then a solution of 26.0 g (250.0 mmol) of trimethyl borate in 50 ml of dry tetrahydrofuran was added dropwise. After the dropwise addition, the reaction solution was stirred at room temperature for 5 h. After adding 200 ml of a 1 N hydrochloric acid, the solution was stirred for one hour and then the aqueous layer was removed. The organic layer was dried over MgSO.sub.4, and the solvent was evaporated off under reduced pressure. The obtained solid was washed with toluene to obtain 15.2 g of a white crystal (yield: 72%).

(16) ##STR00130##
Intermediate Synthesis 1-6 (Synthesis of Intermediate 1-6)

(17) Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of 4-iodobromobenzene, 22.3 g (105.0 mmol) of the intermediate 1-5, and 2.31 g (2.00 mmol) of Pd[PPh.sub.3].sub.4, 150 ml of toluene, 150 ml of dimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution of Na.sub.2CO.sub.3 were added, and the resultant mixture was stirred for 10 h while refluxing under heating.

(18) After the reaction, the obtained mixture was extracted with dichloromethane in a separatory funnel. The organic layer was dried over MgSO.sub.4, and then filtered and condensed. The condensate was purified by silica gel column chromatography to obtain 24.2 g of a white solid, which was identified as the intermediate 1-6 by FD-MS analysis (yield: 75%).

(19) ##STR00131##
Intermediate Synthesis 1-7 (Synthesis of Intermediate 1-7)

(20) In the same manner as in Intermediate Synthesis 1-2 except for using 28.6 g of the intermediate 1-5 in place of dibenzofuran-4-boronic acid, 19.1 g of a white solid was obtained, which was identified as the intermediate 1-7 by FD-MS analysis (yield: 56%).

(21) ##STR00132##
Intermediate Synthesis 1-8 (Synthesis of Intermediate 1-8)

(22) In the same manner as in Intermediate Synthesis 1-3 except for using 18.0 g of the intermediate 1-7 in place of the intermediate 1-2, 14.5 g of a white solid was obtained, which was identified as the intermediate 1-8 by FD-MS analysis (yield: 93%).

(23) ##STR00133##
Intermediate Synthesis 1-9 (Synthesis of Intermediate 1-9)

(24) Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of 4-iodobromobenzene, 23.9 g (105.0 mmol) of dibenzothiophene-4-boronic acid, and 2.31 g (2.00 mmol) of Pd[PPh.sub.3].sub.4, 150 ml of toluene, 150 ml of dimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution of Na.sub.2CO.sub.3 were added, and the resultant mixture was stirred for 10 h while refluxing under heating.

(25) After the reaction, the obtained mixture was cooled to room temperature, and extracted with dichloromethane in a separatory funnel. The organic layer was dried over MgSO.sub.4, and then filtered and condensed. The condensate was purified by silica gel column chromatography to obtain 27.1 g of a white solid, which was identified as the intermediate 1-9 by FD-MS analysis (Field Desorption Mass Spectrometry Analysis) (yield: 80%).

(26) ##STR00134##
Intermediate Synthesis 1-10 (Synthesis of Intermediate 1-10)

(27) Under an argon atmosphere, into a mixture of 24.0 g (112.0 mmol) of 4′-bromoacetanilide, 30.8 g (135.0 mmol) of dibenzothiophene-4-boronic acid, and 2.6 g (2.24 mmol) of Pd[PPh.sub.3].sub.4, 450 ml of toluene, 100 ml of dimethoxyethane, and 110 ml (220.0 mmol) of a 2 M aqueous solution of Na.sub.2CO.sub.3 were added, and the resultant mixture was stirred for 10 h while refluxing under heating.

(28) After the reaction, the obtained mixture was cooled to room temperature, and the precipitated crystal was collected by filtration. The collected crystal was dissolved in tetrahydrofuran and filtered through celite/silica gel. The filtrate was condensed under reduced pressure. The obtained residue was washed with methanol/hexane and dried to obtain 17.8 g of a white solid, which was identified as the intermediate 1-10 by FD-MS analysis (yield: 50%)

(29) ##STR00135##
Intermediate Synthesis 1-11 (Synthesis of Intermediate 1-11)

(30) Into 18.0 g (56.1 mmol) of the intermediate 1-10, 120 ml of xylene, 1200 ml of water, and 60 ml of ethanol were added, and the resultant mixture was stirred. After adding 20.0 g (360.0 mmol) of potassium hydroxide, the mixture was stirred for 10 h while refluxing under heating.

(31) After the reaction, the obtained mixture was cooled to room temperature and extracted with toluene in a separatory funnel. The organic layer was dried over MgSO.sub.4 and then filtered and condensed. The obtained residue was recrystallized from xylene. The crystal was collected by filtration and dried to obtain 14.7 g of a white solid, which was identified as the intermediate 1-11 by FD-MS analysis (yield: 95%).

(32) ##STR00136##
Intermediate Synthesis 1-12 (Synthesis of Intermediate 1-12)

(33) In the same manner as in Intermediate Synthesis 1-5 except for using 26.3 g of 2-bromodibenzothiophene in place of the intermediate 1-4, 15.0 g of a white solid was obtained (yield: 66%).

(34) ##STR00137##
Intermediate Synthesis 1-13 (Synthesis of Intermediate 1-13)

(35) In the same manner as in Intermediate Synthesis 1-6 except for using 23.9 g of the intermediate 1-12 in place of the intermediate 1-5, 25.4 g of a white solid was obtained, which was identified as the intermediate 1-13 by FD-MS analysis (yield: 75%).

(36) ##STR00138##
Intermediate Synthesis 1-14 (Synthesis of Intermediate 1-14)

(37) In the same manner as in Intermediate Synthesis 1-2 except for using 30.8 g of the intermediate 1-12 in place of dibenzofuran-4-boronic acid, 18.1 g of a white solid was obtained, which was identified as the intermediate 1-14 by FD-MS analysis (yield: 51%).

(38) ##STR00139##
Intermediate Synthesis 1-15 (Synthesis of Intermediate 1-15)

(39) In the same manner as in Intermediate Synthesis 1-3 except for using 18.0 g of the intermediate 1-14 in place of the intermediate 1-2, 13.9 g of a white solid was obtained, which was identified as the intermediate 1-15 by FD-MS analysis (yield: 90%).

(40) ##STR00140##
Intermediate Synthesis 2-1 (Synthesis of Intermediate 2-1)

(41) Under an argon atmosphere, into a mixture of 19.9 g (50.0 mmol) of 2-bromo-9,9′-diphenylfluorene, 13.0 g (50.0 mmol) of the intermediate 1-3, and 9.6 g (100.0 mmol) of t-butoxysodium, 250 ml of dry toluene was added, and the resultant mixture was stirred. After adding 225 mg (1.0 mmol) of palladium acetate and 202 mg (1.0 mmol) of tri-t-butylphosphine, the mixture was allowed to react at 80° C. for 8 h.

(42) After cooling, the reaction mixture was filtered through celite/silica gel. The filtrate was condensed under reduced pressure. The obtained residue was recrystallized from toluene and the crystal was collected by filtration and dried to obtain 23.0 g of a white solid, which was identified as the intermediate 2-1 by FD-MS analysis (yield: 80%).

(43) ##STR00141##
Intermediate Synthesis 2-2 (Synthesis of Intermediate 2-2)

(44) In the same manner as in Intermediate Synthesis 2-1 except for using 13.0 g of the intermediate 1-8 in place of the intermediate 1-3, 23.2 g of a white solid was obtained, which was identified as the intermediate 2-2 by FD-MS analysis (yield: 81%).

(45) ##STR00142##
Intermediate Synthesis 2-3 (Synthesis of Intermediate 2-3)

(46) In the same manner as in Intermediate Synthesis 2-1 except for using 10.5 g of 2-amino-9,9′-dimethylfluorene in place of the intermediate 1-3, 19.7 g of a white solid was obtained, which was identified as the intermediate 2-3 by FD-MS analysis (yield: 75%).

(47) ##STR00143##
Intermediate Synthesis 2-4 (Synthesis of Intermediate 2-4)

(48) In the same manner as in Intermediate Synthesis 2-1 except for using 13.8 g of the intermediate 1-11 in place of the intermediate 1-3, 23.7 g of a white solid was obtained, which was identified as the intermediate 2-4 by FD-MS analysis (yield: 80%).

(49) ##STR00144##
Intermediate Synthesis 2-5 (Synthesis of Intermediate 2-5)

(50) In the same manner as in Intermediate Synthesis 2-1 except for using 13.8 g of the intermediate 1-15 in place of the intermediate 1-3, 22.2 g of a white solid was obtained, which was identified as the intermediate 2-5 by FD-MS analysis (yield: 75%).

(51) ##STR00145##
Synthesis Example 1 (Production of Aromatic Amine Derivative H1)

(52) Under an argon atmosphere, into a mixture of 3.2 g (10.0 mmol) of the intermediate 1-1, 5.8 g (10.0 mmol) of the intermediate 2-1, 0.14 g (0.15 mmol) of Pd.sub.2(dba).sub.3, 0.087 g (0.3 mmol) of P(tBu).sub.3HBF.sub.4, and 1.9 g (20.0 mmol) of t-butoxysodium, 50 ml of dry xylene was added, and the resultant mixture was refluxed for 8 h under heating.

(53) After the reaction, the reaction liquid was cooled to 50° C. and filtered through celite/silica gel. The filtrate was condensed and the obtained condensate was purified by silica gel column chromatography to obtain a white solid. The crude product was recrystallized from toluene to obtain 3.7 g of a white crystal, which was identified as the aromatic amine derivative H1 by FD-MS analysis (yield: 45%).

(54) ##STR00146##
Synthesis Example 2 (Production of Aromatic Amine Derivative H2)

(55) In the same manner as in Synthesis Example 1 except for using 3.2 g of the intermediate 1-6 in place of the intermediate 1-1 and using 5.8 g of the intermediate 2-2 in place of the intermediate 2-1, 5.2 g of a white crystal was obtained, which was identified as the aromatic amine derivative H2 by FD-MS analysis (yield: 63%).

(56) ##STR00147##
Synthesis Example 3 (Production of Aromatic Amine Derivative H3)

(57) In the same manner as in Synthesis Example 1 except for using 3.2 g of the intermediate 1-6 in place of the intermediate 1-1, 4.5 g of a white crystal was obtained, which was identified as the aromatic amine derivative H3 by FD-MS analysis (yield: 55%).

(58) ##STR00148##

(59) Synthesis Example 4 (Production of Aromatic Amine Derivative H4)

(60) In the same manner as in Synthesis Example 1 except for using 2.3 g of 4-bromobiphenyl in place of the intermediate 1-1, 3.6 g of a white crystal was obtained, which was identified as the aromatic amine derivative H4 by FD-MS analysis (yield: 50%).

(61) ##STR00149##
Synthesis Example 5 (Production of Aromatic Amine Derivative H5)

(62) Under an argon atmosphere, into a mixture of 2.3 g (10.0 mmol) of 2-bromobiphenyl, 5.3 g (10.0 mmol) of the intermediate 2-3, 0.14 g (0.15 mmol) of Pd.sub.2(dba).sub.3, 0.087 g (0.3 mmol) of P(tBu).sub.3HBF.sub.4, and 1.9 g (20.0 mmol) of t-butoxysodium, 50 ml of dry xylene was added, and the resultant mixture was refluxed for 8 h under heating.

(63) After the reaction, the reaction liquid was cooled to 50° C. and filtered through celite/silica gel. The filtrate was condensed and the obtained condensate was purified by silica gel column chromatography to obtain a white solid. The crude product was recrystallized from toluene to obtain 3.1 g of a white crystal, which was identified as the aromatic amine derivative H5 by FD-MS analysis (yield: 45%).

(64) ##STR00150##
Synthesis Example 6 (Production of Aromatic Amine Derivative H6)

(65) In the same manner as in Synthesis Example 5 except for using 2.3 g of 4-bromobiphenyl in place of 2-bromobiphenyl, 2.7 g of a white crystal was obtained, which was identified as the aromatic amine derivative H6 by FD-MS analysis (yield: 40%).

(66) ##STR00151##

(67) Synthesis Example 7 (Production of Aromatic Amine Derivative H7)

(68) In the same manner as in Synthesis Example 1 except for using 3.4 g of the intermediate 1-9 in place of the intermediate 1-1 and using 5.9 g of the intermediate 2-4 in place of the intermediate 2-1, 4.7 g of a white crystal was obtained, which was identified as the aromatic amine derivative H7 by FD-MS analysis (yield: 55%).

(69) ##STR00152##
Synthesis Example 8 (Production of Aromatic Amine Derivative H8)

(70) In the same manner as in Synthesis Example 1 except for using 3.4 g of the intermediate 1-13 in place of the intermediate 1-1 and using 5.9 g of the intermediate 2-5 in place of the intermediate 2-1, 5.1 g of a white crystal was obtained, which was identified as the aromatic amine derivative H8 by FD-MS analysis (yield: 55%).

(71) ##STR00153##

Example 1-1

(72) Production of Organic EL Device

(73) A glass substrate with an ITO transparent electrode line having a size of 25 mm×75 mm×1.1 mm (manufactured by GEOMATEC Co., Ltd.) was ultrasonically cleaned in isopropyl alcohol for 5 min and then UV (ultraviolet)/ozone cleaned for 30 min.

(74) The cleaned glass substrate with the transparent electrode line was mounted on the substrate holder of a vacuum deposition apparatus. First, the following electron-accepting compound A was vapor-deposited onto the surface on the side where the transparent electrode line was formed so as to cover the transparent electrode, thereby forming a film A having a thickness of 5 nm.

(75) On the film A, the following aromatic amine derivative X1 as a first hole transporting material was vapor-deposited to form a first hole transporting layer having a thickness of 160 nm. Successively after the formation of the first hole transporting layer, the aromatic amine derivative H1 as a second hole transporting material was vapor-deposited to form a second hole transporting layer having a thickness of 10 nm.

(76) On the hole transporting layer, the host compound BH and the dopant compound BD were vapor co-deposited into a film having a thickness of 25 nm, to form a light emitting layer. The concentration of the dopant compound BD was 4% by mass.

(77) On the light emitting layer, the compound ET1 was vapor-deposited in a thickness of 20 nm and then the compound ET2 and Li were vapor co-deposited each in a thickness of 10 nm and 25 nm, thereby forming an electron transporting/injecting layer. The concentration of Li was 4% by mass.

(78) Then, metallic Al was deposited in a thickness of 80 nm to form a cathode, thereby producing an organic EL device.

(79) ##STR00154## ##STR00155##

Examples 1-2 to 1-6

(80) Each organic EL device of Examples 1-2 to 1-6 was produced in the same manner as in Example 1-1 except for using each aromatic amine derivative listed in Table 1 as the second hole transporting material.

(81) ##STR00156## ##STR00157##

Comparative Examples 1-1 and 1-2

(82) Each organic EL device of Comparative Examples 1-1 and 1-2 was produced in the same manner as in Example 1-1 except for using each aromatic amine derivative listed in Table 1 as the second hole transporting material.

(83) ##STR00158##
Evaluation of Emission Performance of Organic EL Device

(84) Each organic EL device thus produced was measured for the luminance (L) and the current density by allowing the device to emit light under a direct current drive. Using the measured results, the current efficiency (L/J) and the driving voltage (V) at a current density of 10 mA/cm.sup.2 were determined. In addition, the organic EL device was measured for the lifetime at a current density of 50 mA/cm.sup.2. The 80% lifetime is the time taken until the luminance was reduced to 80% of the initial luminance when driving the device at constant current. The results are shown in Table 1.

(85) TABLE-US-00001 TABLE 1 Measured Results Emission Driving efficiency voltage First, hole Second hole (cd/A) (V) 80% transporting transporting @ @ Lifetime material material 10 mA/cm.sup.2 10 mA/cm.sup.2 (h) Examples 1-1 X1 H1 6.5 4.2 230 1-2 X1 H2 6.9 4.2 190 1-3 X1 H3 7.2 4.2 220 1-4 X1 H4 6.2 4.0 170 1-5 X1 H7 6.4 4.1 210 1-6 X1 H8 7.0 4.1 180 Comparative Examples 1-1 X1 comparative 5.5 4.2 120 compound 1 1-2 X1 comparative 5.2 4.0 100 compound 2

(86) The results of Table 1 show that an organic EL device having a high efficiency even when driving it at a low voltage and having a long lifetime is obtained by using the aromatic amine derivative of the invention.

Example 2-1

(87) Production of Organic EL Device

(88) A glass substrate with an ITO transparent electrode line having a size of 25 mm×75 mm×1.1 mm (manufactured by GEOMATEC Co., Ltd.) was ultrasonically cleaned in isopropyl alcohol for 5 min and then UV (ultraviolet)/ozone cleaned for 30 min.

(89) The cleaned glass substrate with the transparent electrode line was mounted on the substrate holder of a vacuum deposition apparatus. First, the following electron-accepting compound A was vapor-deposited onto the surface on the side where the transparent electrode line was formed so as to cover the transparent electrode, thereby forming a film A having a thickness of 5 nm.

(90) On the film A, the following aromatic amine derivative H5 as a first hole transporting material was vapor-deposited to form a first hole transporting layer having a thickness of 160 nm. Successively after the formation of the first hole transporting layer, the aromatic amine derivative Y1 as a second hole transporting material was vapor-deposited to form a second hole transporting layer having a thickness of 10 nm.

(91) On the hole transporting layer, the host compound BH and the dopant compound BD were vapor co-deposited into a film having a thickness of 25 nm, to form a light emitting layer. The concentration of the dopant compound BD was 4% by mass.

(92) On the light emitting layer, the compound ET1 was vapor-deposited in a thickness of 20 nm and then the compound ET2 and Li were vapor co-deposited each in a thickness of 10 nm and 25 nm, thereby forming an electron transporting/injecting layer. The concentration of Li was 4% by mass.

(93) Then, metallic Al was deposited in a thickness of 80 nm to form a cathode, thereby producing an organic EL device.

(94) ##STR00159## ##STR00160##

Examples 2-2 to 2-4

(95) Each organic EL device of Examples 2-2 to 2-4 was produced in the same manner as in Example 2-1 except for using the aromatic amine derivatives listed in Table 2 as the first hole transporting material and the second hole transporting material.

(96) ##STR00161##

Comparative Examples 2-1 and 2-2

(97) Each organic EL device of Comparative Examples 2-1 and 2-2 was produced in the same manner as in Examples 2-1 and 2-2, respectively, except for using NPD as the first hole transporting material.

(98) ##STR00162##
Evaluation of Emission Performance of Organic EL Device

(99) Each organic EL device thus produced was measured for the luminance (L) and the current density by allowing the device to emit light under a direct current drive. Using the measured results, the current efficiency (L/J) and the driving voltage (V) at a current density of 10 mA/cm.sup.2 were determined. In addition, the organic EL device was measured for the lifetime at a current density of 50 mA/cm.sup.2. The 80% lifetime is the time taken until the luminance was reduced to 80% of the initial luminance when driving the device at constant current. The results are shown in Table 2.

(100) TABLE-US-00002 TABLE 2 Measured Results Emission Driving efficiency voltage First, hole Second hole (cd/A) (V) 80% transporting transporting @ @ Lifetime material material 10 mA/cm.sup.2 10 mA/cm.sup.2 (h) Examples 2-1 H5 Y1 8.3 4.0 150 2-2 H5 Y2 8.5 4.0 230 2-3 H6 Y1 8.1 4.0 130 2-4 H6 Y2 8.4 4.0 180 Comparative Examples 2-1 NPD Y1 7.2 4.2 110 2-2 NPD Y2 6.2 4.2 130

(101) The results of Table 2 show that an organic EL device having a high efficiency even when driving it at a low voltage and having a long lifetime is obtained by using the aromatic amine derivative of the invention.