Organic electroluminescent compound and organic electroluminescent device comprising the same

Abstract

The present disclosure relates to an organic electroluminescent compound and an organic electroluminescent device comprising the same. By comprising the organic electroluminescent compound of the present disclosure, an organic electroluminescent device having low driving voltage, high luminous efficiency, and/or improved lifespan characteristics can be provided.

Claims

1. An organic electroluminescent compound represented by the following formula 1: ##STR00096## wherein X.sub.1 and X.sub.3 represent CR, and X.sub.2 and X.sub.4 represent N; ##STR00097## is represented by the following formulas: ##STR00098## R and R.sub.11, each independently, represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (5- to 30-membered)heteroaryl containing at least one heteroatom selected from B, N, O, S, Si, and P; R.sub.1 and R.sub.2, each independently, represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a substituted or unsubstituted (5- to 30-membered)heteroaryl containing at least one heteroatom selected from B, N, O, S, Si, and P, a substituted or unsubstituted (3- to 7-membered)heterocycloalkyl containing at least one heteroatom selected from B, N, O, S, Si, and P, or a substituted or unsubstituted (C3-C30)cycloalkyl; or may be linked to each other to form a substituted or unsubstituted, mono- or polycyclic, (3- to 30-membered) alicyclic or aromatic ring, or a combination thereof, whose carbon atom(s) may be replaced with at least one heteroatom selected from nitrogen, oxygen, and sulfur; L represents a single bond, or a substituted or unsubstituted (C6-C30)arylene, and, if n is 0, L is not a single bond; m represents an integer of 0 to 4, n represents an integer of 0 to 2, and m+n is 1 or greater; in which if m and n are 2 or greater, each L and each ##STR00099## may be the same or different, and, wherein, * represents a bonding site with (L).sub.m.

2. The organic electroluminescent compound according to claim 1, wherein in formula 1, L is represented by the following formulas: ##STR00100## ##STR00101## wherein * represents a bonding site.

3. The organic electroluminescent compound according to claim 1, wherein formula 1 is represented by any one of the following formulas 4, and 7: ##STR00102## ##STR00103## wherein Y.sub.1 to Y.sub.5, R, R.sub.1, R.sub.2, L, m, and n are as defined in claim 1.

4. The organic electroluminescent compound according to claim 1, wherein the substituents of the substituted alkyl, the substituted aryl(ene), the substituted heteroaryl(ene), the substituted heterocycloalkyl, the substituted cycloalkyl, and the substituted mono- or polycyclic, alicyclic or aromatic ring, or a combination thereof in R, R.sub.1, R.sub.2, R.sub.11, and L, each independently, are at least one selected from the group consisting of deuterium; a halogen; a cyano; a carboxyl; a nitro; a hydroxyl; a (C1-C30)alkyl; a halo(C1-C30)alkyl; a (C2-C30)alkenyl; a (C2-C30)alkynyl; a (C1-C30)alkoxy; a (C1-C30)alkylthio; a (C3-C30)cycloalkyl; a (C3-C30)cycloalkenyl; a (3- to 7-membered)heterocycloalkyl; a (C6-C30)aryloxy; a (C6-C30)arylthio; a (5- to 30-membered)heteroaryl unsubstituted or substituted with a (C6-C30)aryl(s); a (C6-C30)aryl unsubstituted or substituted with a (5- to 30-membered)heteroaryl(s); a tri(C1-C30)alkylsilyl; a tri(C6-C30)arylsilyl; a di(C1-C30)alkyl(C6-C30)arylsilyl; a (C1-C30)alkyldi(C6-C30)arylsilyl; an amino; a mono- or di-(C1-C30)alkylamino; a mono- or di-(C6-C30)arylamino unsubstituted or substituted with a (C1-C30)alkyl(s); a (C1-C30)alkyl(C6-C30)arylamino; a (C1-C30)alkylcarbonyl; a (C1-C30)alkoxycarbonyl; a (C6-C30)arylcarbonyl; a di(C6-C30)arylboronyl; a di(C1-C30)alkylboronyl; a (C1-C30)alkyl(C6-C30)arylboronyl; a (C6-C30)aryl(C1-C30)alkyl; and a (C1-C30)alkyl(C6-C30)aryl.

5. The organic electroluminescent compound according to claim 1, wherein R and R.sub.11, each independently, represent hydrogen, a substituted or unsubstituted (C6-C25)aryl, or a substituted or unsubstituted (5- to 15-membered)heteroaryl; R.sub.1 and R.sub.2, each independently, represent hydrogen; and L represents a single bond, a substituted or unsubstituted (C6-C25)aryl(ene), or a substituted or unsubstituted (5- to 20-membered)heteroaryl(ene).

6. The organic electroluminescent compound according to claim 1, wherein R and R.sub.11, each independently, represent hydrogen, a (C6-C25)aryl unsubstituted or substituted with a (C1-C6)alkyl(s) or a (5- to 15-membered)heteroaryl(s), or a (5- to 15-membered)heteroaryl unsubstituted or substituted with a (C6-C12)aryl(s); R.sub.1 and R.sub.2, each independently, represent hydrogen; and L represents a single bond, a (C6-C25)aryl(ene) unsubstituted or substituted with a (C1-C6)alkyl(s), or a (5- to 20-membered)heteroaryl(ene) unsubstituted or substituted with a (C6-C12)aryl(s).

7. The organic electroluminescent compound according to claim 1, wherein the compound represented by formula 1 is at least one selected from the group consisting of: ##STR00104## ##STR00105## ##STR00106## ##STR00107## ##STR00108## ##STR00109## ##STR00110## ##STR00111## ##STR00112## ##STR00113## ##STR00114## ##STR00115## ##STR00116## ##STR00117## ##STR00118## ##STR00119## ##STR00120## ##STR00121## ##STR00122## ##STR00123## ##STR00124## ##STR00125## ##STR00126## ##STR00127## ##STR00128## ##STR00129## ##STR00130## ##STR00131## ##STR00132## ##STR00133## ##STR00134## ##STR00135## ##STR00136## ##STR00137## ##STR00138## ##STR00139## ##STR00140##

8. An organic electroluminescent device comprising the organic electroluminescent compound according to claim 1.

Description

EXAMPLE 1: PREPARATION OF COMPOUND C-6

(1) ##STR00078## ##STR00079##

(2) Preparation of Compound 1-1

(3) 20 g of 7-chloro-3,4-dihydronaphthalen-1(2H)-one (110.72 mmol), 13 g of benzaldehyde (121.80 mmol), 6.6 g of sodium hydroxide (166.08 mmol), and 360 mL of ethanol were introduced into a reaction vessel and stirred at room temperature for 2 hours. After completion of the reaction, the resulting solid was filtered and washed with ethanol to obtain 25.2 g of compound 1-1 (yield: 85%).

(4) Preparation of Compound 1-2

(5) 25.2 g of compound 1-1 (93.77 mmol), 16.2 g of benzimidamide (103.15 mmol), 6.8 g of sodium hydroxide (281.31 mmol), and 312 mL of ethanol were introduced into a reaction vessel and stirred for 20 hours under reflux. After completion of the reaction, the resulting solid was filtered and washed with ethanol to obtain 34.5 g of compound 1-2 (yield: 100%).

(6) Preparation of Compound 1-3

(7) 34.5 g of compound 1-2 (93.77 mmol), 43 g of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (189.77 mmol), and 474 mL of chlorobenzene (MCB) were introduced into a reaction vessel and stirred for 18 hours under reflux. After completion of the reaction, the resulting product was washed with distilled water and extracted with ethyl acetate. The extracted organic layer was then dried with magnesium sulfate and the solvent was removed by a rotary evaporator. The residue was purified by column chromatography to obtain 15.5 g of compound 1-3 (yield: 45%).

(8) Preparation of Compound 1-4

(9) 15.5 g of compound 1-3 (42.25 mmol), 12.9 g of bis(pinacolato)diborane (50.70 mmol), 1.6 g of tris(dibenzylideneacetone)dipalladium (1.69 mmol), 1.4 g of 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (3.38 mmol), 12.4 g of potassium acetate (126.75 mmol), and 210 mL of 1,4-dioxane were introduced into a reaction vessel and stirred at 130° C. for 6 hours under reflux. After completion of the reaction, the resulting product was cooled to room temperature and extracted with ethyl acetate. The extracted organic layer was then dried with magnesium sulfate and the solvent was removed by a rotary evaporator. The residue was purified by column chromatography to obtain 14 g of compound 1-4 (yield: 72%).

(10) Preparation of Compound C-6

(11) 5 g of compound 1-4 (10.9 mmol), 3.2 g of 2-chloro-4,6-diphenyltriazine (12 mmol), 0.4 g of tetrakis(triphenylphosphine)palladium (0.33 mmol), 2.9 g of sodium carbonate (27.28 mmol), 55 mL of toluene, 14 mL of ethanol, and 14 mL of distilled water were introduced into a reaction vessel and stirred at 120° C. for 4 hours. After completion of the reaction, the precipitated solid was washed with distilled water and methanol. The residue was purified by column chromatography to obtain 5 g of compound C-6 (yield: 82%).

(12) TABLE-US-00001 MW UV PL M.P. C-6 563.66 340 nm 411 nm 314° C.

EXAMPLE 2: PREPARATION OF COMPOUND C-36

(13) ##STR00080##

(14) 3.2 g of compound 1-4 (7.0 mmol), 3.2 g of 2-([1,1′-biphenyl]-4-yl)-4-(3-chlorophenyl)-6-phenyl-1,3,5-triazine (7.7 mmol), 0.6 g of tris(dibenzylideneacetone)dipalladium (0.70 mmol), 0.6 g of 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (1.40 mmol), 1.0 g of sodium tert-butoxide (10.47 mmol), and 35 mL of o-xylene were introduced into a reaction vessel and stirred for 3 hours under reflux. After completion of the reaction, the resulting product was washed with distilled water and extracted with ethyl acetate. The extracted organic layer was then dried with magnesium sulfate and the solvent was removed by a rotary evaporator. The residue was purified by column chromatography to obtain 2 g of compound C-36 (yield: 42%).

(15) TABLE-US-00002 MW UV PL M.P. C-36 715.84 344 nm 419 nm 336° C.

EXAMPLE 3: PREPARATION OF COMPOUND C-37

(16) ##STR00081##

(17) 5 g of compound 1-3 (12 mmol), 5.3 g of 2,4-diphenyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1,3,5-triazine (12 mmol), 0.4 g of tetrakis(triphenylphosphine)palladium (0.33 mmol), 3.2 g of sodium carbonate (30 mmol), 61 mL of toluene, 15 mL of ethanol, and 15 mL of distilled water were introduced into a reaction vessel and stirred at 120° C. for 4 hours. After completion of the reaction, the precipitated solid was washed with distilled water and methanol. The residue was purified by column chromatography to obtain 3.4 g of compound C-37 (yield: 44%).

(18) TABLE-US-00003 MW UV PL M.P. C-37 639.76 334 nm 419 nm 323° C.

Comparative Example 1: Producing a Blue Light-Emitting Oled Device not ACCORDING TO THE PRESENT DISCLOSURE

(19) An OLED device not according to the present disclosure was produced as follows: A transparent electrode indium tin oxide (ITO) thin film (10 Ω/sq) on a glass substrate for an OLED (Geomatec Co., Ltd., Japan) was subjected to an ultrasonic washing with acetone and isopropyl alcohol, sequentially, and then was stored in isopropanol. Next, the ITO substrate was mounted on a substrate holder of a vacuum vapor deposition apparatus. Compound HI-1 was introduced into a cell of the vacuum vapor deposition apparatus, and the pressure in the chamber of the apparatus was then controlled to 10.sup.−7 torr. Thereafter, an electric current was applied to the cell to evaporate the introduced material, thereby forming a first hole injection layer having a thickness of 60 nm on the ITO substrate. Compound HI-2 was then introduced into another cell of the vacuum vapor deposition apparatus, and an electric current was applied to the cell to evaporate the introduced material, thereby forming a second hole injection layer having a thickness of 5 nm on the first hole injection layer. Compound HT-1 was introduced into another cell of the vacuum vapor deposition apparatus. Thereafter, an electric current was applied to the cell to evaporate the introduced material, thereby forming a first hole transport layer having a thickness of 20 nm on the second hole injection layer. Compound HT-2 was then introduced into another cell of the vacuum vapor deposition apparatus, and an electric current was applied to the cell to evaporate the introduced material, thereby forming a second hole transport layer having a thickness of 5 nm on the first hole transport layer. After forming the hole injection layers and the hole transport layers, a light-emitting layer was then deposited as follows. Compound H-15 as a host was introduced into one cell of the vacuum vapor deposition apparatus and compound D-38 as a dopant was introduced into another cell of the apparatus. The two materials were evaporated at a different rate and the dopant was deposited in a doping amount of 2 wt %, based on the total weight of the host and dopant, to form a light-emitting layer having a thickness of 20 nm on the second hole transport layer. Next, compound X and compound EIL-1 were evaporated in a weight ratio of 1:1 as electron transport materials to form an electron transport layer having a thickness of 35 nm on the light-emitting layer. After depositing compound EI-1 as an electron injection layer having a thickness of 2 nm on the electron transport layer, an Al cathode having a thickness of 80 nm was deposited by another vacuum vapor deposition apparatus on the electron injection layer. Thus, an OLED device was produced. All the materials used for producing the OLED device were purified by vacuum sublimation at 10.sup.−6 torr.

(20) The driving voltage, luminous efficiency, and color coordinates at a luminance of 1 mA/cm.sup.2, and the time period for the luminance to decrease from 100% to 90% (lifespan; T90) at a luminance of 2,000 nits of the produced OLED device are provided in Table 1 below.

Comparative Examples 2 and 3: Producing a Blue Light-Emitting Oled Device not According to the Present Disclosure

(21) In Comparative Examples 2 and 3, OLED devices were produced in the same manner as in Comparative Example 1, except that compounds shown in Table 1 below were used as an electron transport material. The evaluation results of the OLED devices of Comparative Examples 2 and 3 are provided in Table 1 below.

Device Examples 1 and 2: Producing a Blue Light-Emitting Oled Device Comprising the Compound According to the Present Disclosure

(22) In Device Examples 1 and 2, OLED devices were produced in the same manner as in Comparative Example 1, except that compounds shown in Table 1 below were used as an electron transport material. The evaluation results of the OLED devices of Device Examples 1 and 2 are provided in Table 1 below.

(23) TABLE-US-00004 TABLE 1 Electron Driving Luminous Color Color Lifespan Transport Voltage Efficiency Coordinate Coordinate T90 Material (V) (cd/A) (x) (y) (hr) Comparative Compound 3.2 4.1 0.139 0.086 39.0 Example 1 X Comparative Compound 3.1 4.8 0.139 0.087 33.6 Example 2 Y Comparative Compound 3.7 2.2 0.140 0.093 5.5 Example 3 Z Device C-36 3.1 5.2 0.139 0.089 42.4 Example 1 Device C-6 3.1 5.1 0.139 0.089 60.6 Example 2

(24) It is verified that the OLED devices comprising the compound of the present disclosure as an electron transport material have better lifespan characteristic, while exhibiting driving voltage and luminous efficiency characteristics at equivalent or better levels, compared to the OLED devices comprising the compound of the Comparative Examples.

Comparative Example 4: Producing a Blue Light-Emitting Oled Device not According to the Present Disclosure

(25) An OLED device not according to the present disclosure was produced as follows: A transparent electrode indium tin oxide (ITO) thin film (10 Ω/sq) on a glass substrate for an OLED (Geomatec Co., Ltd., Japan) was subjected to an ultrasonic washing with acetone and isopropyl alcohol, sequentially, and then was stored in isopropanol. Next, the ITO substrate was mounted on a substrate holder of a vacuum vapor deposition apparatus. Compound HI-1 was introduced into a cell of the vacuum vapor deposition apparatus, and the pressure in the chamber of the apparatus was then controlled to 10.sup.−7 torr. Thereafter, an electric current was applied to the cell to evaporate the introduced material, thereby forming a first hole injection layer having a thickness of 60 nm on the ITO substrate. Compound HI-2 was then introduced into another cell of the vacuum vapor deposition apparatus, and an electric current was applied to the cell to evaporate the introduced material, thereby forming a second hole injection layer having a thickness of 5 nm on the first hole injection layer. Compound HT-1 was introduced into another cell of the vacuum vapor deposition apparatus. Thereafter, an electric current was applied to the cell to evaporate the introduced material, thereby forming a first hole transport layer having a thickness of 20 nm on the second hole injection layer. Compound HT-2 was then introduced into another cell of the vacuum vapor deposition apparatus, and an electric current was applied to the cell to evaporate the introduced material, thereby forming a second hole transport layer having a thickness of 5 nm on the first hole transport layer. After forming the hole injection layers and the hole transport layers, a light-emitting layer was then deposited as follows. Compound H-15 as a host was introduced into one cell of the vacuum vapor deposition apparatus and compound D-38 as a dopant was introduced into another cell of the apparatus. The two materials were evaporated at a different rate and the dopant was deposited in a doping amount of 2 wt %, based on the total weight of the host and dopant, to form a light-emitting layer having a thickness of 20 nm on the second hole transport layer. Next, compound ET-1 and compound EI-1 were evaporated in a weight ratio of 1:1 as electron transport materials to form an electron transport layer having a thickness of 35 nm on the light-emitting layer. After depositing compound EI-1 as an electron injection layer having a thickness of 2 nm on the electron transport layer, an Al cathode having a thickness of 80 nm was deposited by another vacuum vapor deposition apparatus on the electron injection layer. Thus, an OLED device was produced. All the materials used for producing the OLED device were purified by vacuum sublimation at 10.sup.−6 torr.

Comparative Example 5: Producing a Blue Light-Emitting Oled Device not ACCORDING TO THE PRESENT DISCLOSURE

(26) In Comparative Example 5, an OLED device was produced in the same manner as in Comparative Example 4, except that the thickness of an electron transport layer was reduced to 30 nm, and compound Y was inserted as an electron buffer layer having a thickness of 5 nm between the light-emitting layer and the electron transport layer.

Device Examples 3 to 5: Producing a Blue Light-Emitting Oled Device Comprising the Compound of the Present Disclosure

(27) In Device Examples 3 to 5, OLED devices were produced in the same manner as in Comparative Example 4, except that the thickness of an electron transport layer was reduced to 30 nm, and each of compounds C-6, C-36, and C-37 was inserted as an electron buffer layer having a thickness of 5 nm between the light-emitting layer and the electron transport layer.

(28) The driving voltage and light emission color at a luminance of 1,000 nits, and the time period for the luminance to decrease from 100% to 90% (lifespan; T90) at a luminance of 2,000 nits of the OLED devices produced in Comparative Examples 4 and 5, and Device Examples 3 to 5 are provided in Table 2 below.

(29) TABLE-US-00005 TABLE 2 Electron Driving Light Lifespan Buffer Voltage Emission T90 Material (V) Color (hr) Comparative — 4.4 Blue 55.4 Example 4 Comparative Compound Y 4.2 Blue 46.9 Example 5 Device Example 3 C-6 4.7 Blue 72.0 Device Example 4 C-36 4.6 Blue 63.0 Device Example 5 C-37 4.4 Blue 56.1

(30) It is verified that the OLED devices comprising the compound of the present disclosure as an electron buffer material have better lifespan characteristic compared to the OLED devices which do not contain an electron buffer layer or comprise a conventional material as an electron buffer material.

(31) TABLE-US-00006 TABLE 3 Compounds used in Device Examples and Comparative Examples Hole Injection Layer/ Hole Transport Layer Light-Emitting Layer Electron Buffer Layer/ Electron Transport Layer/ Electron Injection Layer 0