Polyheteroaromatic compound and organic electroluminescence device using the same

Abstract

The present invention discloses a novel polyheteroaromatic compound derived from 7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1,2-b:5,4-b-dithiophene-4,13-indeno[1,2-b]acridine] core structures. The polyheteroaromatic compound can be used as organic electroluminescence materials for use in an organic electroluminescence device and electronic equipment.

Claims

1. A polyheteroaromatic compound of formula (1) below: ##STR00081## wherein X is O, S, or Se; each n and p is independently an integer of 0 to 2; L represents formula (2) below: ##STR00082## and B represents formula (3) below: ##STR00083## wherein m is an integer of 0 to 4; Y is O, S, Se, CR.sub.6R.sub.7, NR.sub.8, or SiR.sub.9R.sub.10; and R.sub.1 to R.sub.11 are independently selected from the group consisting of a hydrogen atom, a halide, a substituted or unsubstituted alkyl group having 1 to 60 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 60 carbon atoms, and a substituted or unsubstituted arylamine group having 6 to 60 carbon atoms.

2. The polyheteroaromatic compound according to claim 1, wherein R.sub.8 or R.sub.11 represents one of the following substituents: ##STR00084## ##STR00085## ##STR00086## ##STR00087## ##STR00088## ##STR00089## ##STR00090## ##STR00091## ##STR00092## ##STR00093## ##STR00094## ##STR00095##

3. The polyheteroaromatic compound according to claim 1, wherein the polyheteroaromatic compound is represented by one of the following formula (4) to formula (9): ##STR00096## ##STR00097## wherein X, n, p, L, m, Y and R.sub.1 to R.sub.11 have the same meaning as defined in claim 1.

4. The polyheteroaromatic compound according to claim 3, wherein R.sub.8 or R.sub.11 represents one of the following substituents: ##STR00098## ##STR00099## ##STR00100## ##STR00101## ##STR00102## ##STR00103## ##STR00104## ##STR00105## ##STR00106## ##STR00107## ##STR00108## ##STR00109## ##STR00110## ##STR00111##

5. The polyheteroaromatic compound according to claim 1, wherein the polyheteroaromatic compound is one of the following compounds: ##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## ##STR00141## ##STR00142## ##STR00143## ##STR00144## ##STR00145## ##STR00146## ##STR00147## ##STR00148## ##STR00149## ##STR00150## ##STR00151## ##STR00152## ##STR00153## ##STR00154## ##STR00155## ##STR00156## ##STR00157## ##STR00158## ##STR00159## ##STR00160## ##STR00161## ##STR00162## ##STR00163## ##STR00164## ##STR00165## ##STR00166## ##STR00167## ##STR00168## ##STR00169## ##STR00170## ##STR00171## ##STR00172## ##STR00173## ##STR00174## ##STR00175## ##STR00176##

6. An organic electroluminescence device, comprising a pair of electrodes composed of a cathode and an anode, and a light emitting layer and one or more organic thin film layers between the pair of electrodes, wherein at least one of the light emitting layer and the organic thin film layer comprises the polyheteroaromatic compound according to claim 1.

7. The organic electroluminescence device according to claim 6, wherein the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a host material.

8. The organic electroluminescence device according to claim 6, wherein the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a fluorescent dopant material.

9. The organic electroluminescence device according to claim 6, wherein the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a thermally activated delayed fluorescence host material.

10. The organic electroluminescence device according to claim 6, wherein the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a thermally activated delayed fluorescence dopant material.

11. The organic electroluminescence device according to claim 6, wherein the organic thin film layer comprising the polyheteroaromatic compound of formula (1) is an electron transporting layer.

12. The organic electroluminescence device according to claim 6, wherein the organic electroluminescence device is a lighting panel.

13. The organic electroluminescence device according to claim 6, wherein the organic electroluminescence device is a backlight panel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The FIGURE shows one embodiment of the organic EL device of the present invention. In the device, hole injection layer 7 is deposited onto transparent electrode 6, hole transport layer 8 is deposited onto hole injection layer 7, fluorescence or phosphorescence emitting layer 9 is deposited onto hole transport layer 8, hole blocking layer 10 is deposited onto emitting layer 9, electron transport layer 11 is deposited onto hole blocking layer 10, electron injection layer 12 is deposited onto electron transport layer 11, and metal electrode 13 is deposited onto electron injection layer 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

(3) In one embodiment of the present invention, a polyheteroaromatic compound which can be used as the host material, the fluorescent dopant material, the thermally activated delayed fluorescence host material, or the thermally activated delayed fluorescence dopant material of the light emitting layer, and/or the electron transporting material for the organic EL device is disclosed. The polyheteroaromatic compound is represented by the following formula (1):

(4) ##STR00004##
wherein X is O, S, or Se; each n and p is independently an integer of 0 to 2; L represents formula (2) below:

(5) ##STR00005##
and B represents formula (3) below:

(6) ##STR00006##
wherein m is an integer of 0 to 4; Y is O, S, Se, CR.sub.6R.sub.7, NR.sub.8, or SiR.sub.9R.sub.10; and R.sub.1 to R.sub.11 are independently selected from the group consisting of a hydrogen atom, a halide, a substituted or unsubstituted alkyl group having 1 to 60 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 60 carbon atoms, and a substituted or unsubstituted arylarnine group having 6 to 60 carbon atoms.

(7) In some embodiments, R.sub.8 or R.sub.11 represents one of the following substituents:

(8) ##STR00007## ##STR00008## ##STR00009## ##STR00010## ##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019##

(9) Preferably, the polyheteroaromatic compound is represented by one of the following formula (4) to formula (9):

(10) ##STR00020## ##STR00021##
wherein X, n, p, L, m, Y and R.sub.1 to R.sub.11 have the same meaning as defined above.

(11) Preferably, the polyheteroaromatic compound is one of the following compounds:

(12) ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047## ##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052## ##STR00053## ##STR00054## ##STR00055## ##STR00056## ##STR00057## ##STR00058## ##STR00059## ##STR00060## ##STR00061## ##STR00062## ##STR00063##

(13) In another embodiment of the present invention, an organic electroluminescence device is disclosed. The organic electroluminescence device comprises a pair of electrodes composed of a cathode and an anode, and a light emitting layer and one or more organic thin film layers between the pair of electrodes. At least one of the light emitting layer and the organic thin film layer comprises the polyheteroaromatic compound of formula (1).

(14) In some embodiments, the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a host material. The host material may be a phosphorescent host material or a fluorescenct host material. In certain embodiments, the light emitting layer comprising the polyheteroaromatic compound of formula (1) is used as a fluorescent dopant. material.

(15) In some embodiments, the light emitting layer comprising the polyheteroaromatic compound of formula (1) is a thermally activated delayed fluorescence host material. In other embodiments, the light emitting layer comprising the polyheteroaromatic compound of formula (1) is used as a thermally activated delayed fluorescence dopant material. In some embodiments, the organic thin film layer comprising the polyheteroaromatic compound of formula (1) is an electron transporting layer.

(16) In a further embodiment of the present invention, the organic electroluminescence device is a lighting panel. In other embodiment of the present invention, the organic electroluminescence device is a backlight panel.

(17) Detailed preparation of the polyheteroaromatic compounds of the present invention will be clarified by exemplary embodiments below, but the present invention is not limited thereto. EXAMPLES 1 to 6 show the preparation of the polyheteroaromatic compounds of the present invention, and EXAMPLE 7 shows the fabrication and test report of the organic EL device.

EXAMPLE 1

Synthesis of N-(2-bromophenyl)-9,9-dimethyl-9H-fluoren-2-amine

(18) ##STR00064##

(19) A mixture of 10 g (35.3 mmol) of 1-bromo-2-iodobenzene, 7.4 g (35.3 mmol) of 9,9-dimethyl-9H-fluoren-2-amine, 0.52 g (0.7 mmol) of Pd(dppf)Cl.sub.2, 6.8 g (70.6 mmol) of sodium tert-butoxide, and 60 ml of toluene was degassed and placed under nitrogen, and then heated at 100 C. for 2 h. After the reaction was finished, the mixture was allowed to cool to room temperature and then filtered to remove the solvent. The crude product was purified by column chromatography, yielding 9.4 g of yellow solid (73%). .sup.1H NMR (CDCl3, 400 MHz): chemical shift (ppm) 8.11 (d, 1H), 7.65 (d, 1H), 7.55 (d, 2H), 7.43 (m, 1H), 7.31 (m, 1H), 7.18 (m, 2H), 6.68-6.74 (m, 2H), 6.50-6.56 (m, 2H) , 4.11 (s, 1H), 1.68 (s, 6H).

Synthesis of 7,7-dimethyl-5,7-dihydrospiro[cyclopenta-[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine]

(20) ##STR00065##

(21) A mixture of 5 g (13.7 mmol) of N-(2-bromophenyl)-9,9-dimethyl-9H-fluoren-2-amine and 100 ml of THF was cooled in a dry ice bath, and then 8.2 ml of n-butvllithium (2.5 M in Hexane, 20.6 mmol) was added dropwisely thereto and then stirred for 1 h in a dry ice bath. Afterwards, 2.9 g of 4H-cyclopenta[1,2-b:5,4-b]-dithiophen-4-one dissolved in 20 ml of THF was added dropwisely and stirred for 1 h at the room temperature, and then heated at 70 C. for 12 h. The solvent was removed from the resulting mixture under reduced pressure. Subsequently, 1.58 g of methanesulfonic acid and 50 ml of CHCl.sub.3 were added and then stirred at 60 C. for 2 h. After the reaction was finished, the mixture was allowed to cool to room temperature and the solvent was removed. The crude product was purified by column chromatography, yielding 1.64 g of brown solid (26%). .sup.1H NMR (CDCl3, 400 MHz): chemical shift (ppm) 8.05 (d, 1H), 7.61 (m, 3H), 7.44 (d, 2H), 7.27-7.33 (m, 1H), 6.92 -7.01 (m, 4H), 6.64-6.68 (m, 2H),6.48 (d, H),4.13 (s, 1H), 1.66 (s, 6H).

(22) Synthesis of compound C3

(23) ##STR00066##

(24) A mixture of 1 g (2.18 mmol) of 7,7-dimethyl-5,7-dihydrospiro-[cyclopenta-[2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine], 0.93 g (2.39 mmol) of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine, 0.04 g (0.04 mmol) of Pd.sub.2(dba).sub.3, and 30 ml of o-xylene was degassed and placed under nitrogen, and then heated at 120 C. for 3 h. After the reaction was finished, the mixture was allowed to cool to room temperature. Subsequently, 50 ml of methanol was added to the mixture, which was then filtered and washed by methanol, yielding 1.13 g of yellow solid (68%). .sup.1H NMR (CDCl3, 400 MHz): chemical shift (ppm) 8.35 (d, 4H), 7.93 (d, 1H),7.69 (d, 1H), 7.52-7.59 (m, 7H), 7.34-7.42 (m, 6H), 7.26 (m, 1H), 6.96-7.02 (m, 3H), 6.86 (d, 1H), 6.61-6.67 (d, 3H), 6.52 (d, 1H), 1.69 (s, 6H). MS (m/z, EI.sup.+): 766.7.

EXAMPLE 2

Synthesis of Compound C12

(25) ##STR00067##

(26) The same synthesis procedure as in EXAMPLE 1 was used, except that 12-(3-bromophenyl)-4,6-diphenylpyrimidine was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the compound of 5-(3-(4,6-diphenylpyrimidin-2-yl)phenyl)-7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine]. MS (m/z, EI.sup.+): 765.6.

EXAMPLE 3

Synthesis of Compound C5

(27) ##STR00068##

(28) The same synthesis procedure as in EXAMPLE 1 was used, except that 9-(3-bromophenyl)-9H-carbazole was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the desired compound of 5-(3-(9H-carbazol-9-yl)phenyl)-7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1, 2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine]. MS (m/z, EI.sup.+):700.6.

EXAMPLE 4

Synthesis of Compound C7

(29) ##STR00069##

(30) The same synthesis procedure as in EXAMPLE 1 was used, except that 2-bromodibenzo[b,d]thiophene was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the desired compound of 5-(dibenzo[b,d]thiophen-2-yl)-7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine]. MS (m/z, EI.sup.+): 641.5.

EXAMPLE 5

Synthesis of Compound C8

(31) ##STR00070##

(32) The same synthesis procedure as in EXAMPLE 1 was used, except that 2-bromo-9,9-dimethyl-9H-fluorene was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the desired compound of 5-(9,9-dimethyl-9H-fluoren-2-yl)-7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]acridine]. MS (m/z, EI.sup.+): 651.6.

EXAMPLE 6

Synthesis of Compound C6

(33) ##STR00071##

(34) The same synthesis procedure as in EXAMPLE 1 was used, except that 6-bromo-9,9-diphenyl-9H,9H-3,3-bicarbazole was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the desired compound of 5-(9,9-diphenyl-9H,9H-[3,3-bicarbazol]-6-yl)-7,7-dimethyl-5,7-dihydrospiro[cyclopenta[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b]-acridine]. MS (m/z, EI.sup.+): 942.1.

EXAMPLE 7

Synthesis of Compound C1

(35) ##STR00072##

(36) The same synthesis procedure as in EXAMPLE 1 was used, except that 1-bromanaphthalene was used instead of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine to obtain the desired compound of 7,7-dimethyl-5-(naphthalen-1-yl)-5,7-dihydrospiro-[cyclopenta[1,2-b:5,4-b]dithiophene-4,13-indeno[1,2-b[acridine]. MS (m/z, EI.sup.+): 585.6.

General Method of Producing Organic EL Device

(37) ITO-coated glasses with 912 ohm/square in resistance and 120-160 nm in thickness are provided (hereinafter ITO substrate) and cleaned in a number of cleaning steps in an ultrasonic bath (e.g. detergent, deionized water). Before vapor deposition of the organic layers, cleaned ITO substrates are further treated by UV and ozone. All pre-treatment processes for ITO substrate are under clean room (class 100).

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

(39) Dipyrazino[2,3-f:2,3-]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) is used to form the hole injection layer of the organic EL device. N,N-bis(naphthalene-1-yl)-N,N-bis(phenyl)-benzidine (NPB) is used to form the hole transporting layer. Bis(2-phenylpyridinato)(2,4-diphenylpyridinato)-iridium(III) (D1) is used as the phosphorescent dopant and 3-(9,9-dimethyl-acridin-10(9H)-yl)-9H-xanthen-9-one (D2) is used as the fluorescent dopant. 4-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-13-yl)dibenzo[b,d]thiophene (H1) is used as the phosphorescent host material, and dibenzo[b,d]thiophene-2,8-diylbis(diphenylphosphine oxide) (H2) is used as the fluorescent host material and TADF host material. 2-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-13-yl)-9-phenyl-1,10-phenanthroline (ET1) is used as the electron transporting material. Compound C12 is used as fluorescent dopant material to compare with compound D2, and compound C3 is used as TADF dopant material to compare with compound A. Compound C5 and C7 are used as phosphorescent host materials to compare with compound H1. Compound C8 is used as fluorescent host material to compare with compound H2, and compound C6 is used as TADF host material to compare with compound H2. Compound C 1 is used as electron transporting material to compare with compound ET1. The chemical structures of conventional OLED materials and the exemplary polyheteroaromatic compounds of the present invention for producing control and exemplary organic EL devices in this invention are shown as follows:

(40) ##STR00073## ##STR00074## ##STR00075## ##STR00076##

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

(42) ##STR00077##

EXAMPLE 7

(43) Using a procedure analogous to the above mentioned general method, organic EL devices emitting green light and having the following device structure as shown in the FIGURE were produced: ITO/HAT-CN (20 nm)/NPB (130 nm)/Host doped with Dopant (30 nm)/ETM/LiQ/Al (160 nm). The I-V-B (at 1000 nits) test reports of these organic EL devices are summarized in Table 1 below.

(44) TABLE-US-00001 TABLE 1 Voltage Efficiency Dopant (%) Host ETM (V) (cd/A) D1 (8%) H1 ET1 4.9 14 D1 (8%) C5 ET1 4.6 20 D1 (8%) C7 ET1 4.8 16 D2 (20%) H2 ET1 5.1 11 D2 (20%) C8 ET1 4.7 13 C12 (20%) H2 ET1 4.9 15 A (20%) H2 ET1 5 10 A (20%) C6 ET1 4.8 13 C3 (20%) H2 ET1 4.7 22 C3 (20%) H2 C1 4.5 25

(45) From the above test report summary of the organic EL devices, it is obvious that the polyheteroaromatic compound of formula (1) used as the fluorescenct or TADF dopant material, the phosphorescent, fluorescenct or TADF host material, or the electron transfer material of the organic EL device exhibits better performance than the prior art materials. In particular, the organic EL devices of the present invention employing the polyheteroaromatic compound of formula (1) as the dopant material, the host material, or the electron transfer material to collocate with the host material H2 or the dopant material D1, D2, or compound A have lower power consumption and higher luminous efficiency.

(46) To sum up, the present invention discloses a polyheteroaromatic compound, which can be used as the host material, the fluorescent dopant material, the thermally activated delayed fluorescence host material, or the thermally activated delayed fluorescence dopant material of the light emitting layer, or the electron transporting material in organic EL devices. The mentioned polyheteroaromatic compound is represented by the following formula (1):

(47) ##STR00078##
wherein X is O, S, or Se; each n and p is independently an integer of 0 to 2; L represents formula (2) below:

(48) ##STR00079##
and B represents formula (3) below:

(49) ##STR00080##
wherein m is an integer of 0 to 4; Y is O, S, Se, CR.sub.6R.sub.7, NR.sub.8, or SiR.sub.9R.sub.10; and R.sub.1 to R.sub.11 are independently selected from the group consisting of a hydrogen atom, a halide, a substituted or unsubstituted alkyl group having 1 to 60 carbon atoms, a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 60 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 60 carbon atoms, and a substituted or unsubstituted arylamine group having 6 to 60 carbon atoms.

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