DE102011111328A1 - New organometallic iridium complexes useful in organic electroluminescent device such as mobile telephones, personal digital assistant and notebook computers - Google Patents

Abstract

Organometallic iridium complexes (Q) are new. Organometallic iridium complexes (Q) of formula (I) or (II) are new. R : alkyl or cycloalkyl, preferably CH 3, C 2H 5, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, sec-pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, hendecyl or dodecyl. Independent claims are included for: (1) an organic electroluminescent device (10) comprising a pair of electrodes and an electroluminescent element (16) between the pair of electrodes, where the electroluminescent element is (Q); and (2) a composition comprising an organic electroluminescent host material and (Q). [Image].

Description

BACKGROUND

area

The present invention relates to an organometallic compound and an organic electroluminescent device using the same, and more particularly to an organometallic phosphorescent compound and a phosphorescent organic electroluminescent device using the same.

Recently, with the development and widespread use of electronic products such as mobile phones, PDAs and notebook computers, the demand for flat panel display devices that consume less power and take up less space has been increasing. Organic electroluminescent devices are self-emissive and very bright at wide viewing angles, fast response rates, and simple manufacturing techniques, and are therefore very popular in the display industry.

An organic electroluminescent device generally consists of a light-emitting layer sandwiched between a pair of electrodes. When an electric field is applied to the electrodes, the cathode injects electrons into the light-emitting layer, and the anode injects holes into the light-emitting layer. Upon reunification of the electrons with the holes in the light emission layer, excitons are formed. The recombination of the electron and hole leads to light emission.

Depending on the spin states of the hole and the electron, the exciton resulting from the recombination of the hole and the electron may have either a triplet or singlet spin state. Luminescence of a singlet exciton leads to fluorescence, whereas luminescence of a triplet exciton leads to phosphorescence. The emission efficiency of the phosphorescence is three times the fluorescence. Therefore, it is crucial to develop high-efficiency phosphorescent material to increase the emission efficiency of an OLED.

An OLED is usually classified into a micromolecular and high molecular weight OLED depending on its substrate type. An OLED having a micromolecular substrate is generally made by vacuum evaporation, so that the micromolecular materials have a good film-forming quality. However, 95% of the organic electroluminescent materials are deposited on the chamber wall of the manufacturing equipment used to make the OLED so that after the manufacturing process only 5% of the organic electroluminescent materials are deposited on a substrate, resulting in high investment costs.

Therefore, a measurement method (such as spin coating or knife coating) has been provided for manufacturing micromolecular OLEDs to improve the utilization ratio of organic electroluminescent materials and to reduce the cost of producing OLEDs. Unfortunately, conventional phosphorescent organic electroluminescent materials are not suitable for use in the wet process because of their poor solubility. Therefore, in order to solve the above problems, it is necessary to develop new phosphorescent organic compounds (especially for orange dopants) which are suitable for use in a measuring process for producing phosphorescent OLEDs.

SUMMARY

worin R für eine Alkylgruppe oder Cycloalkylgruppe steht.An exemplary embodiment of an organometallic compound has the formula (I) and (II):

wherein R is an alkyl group or cycloalkyl group.

In another exemplary embodiment of the disclosure, an organic electroluminescent device is provided. The device includes a pair of electrodes and an electroluminescent element disposed between the pair of electrodes, the electroluminescent element containing the above-listed organometallic compound (serving as an orange dopant).

Yet another exemplary embodiment provides a composition containing an organic electroluminescent diode host material and the above-listed organometallic compound (uniformly dispersed in a solvent). The host material For an organic electroluminescent diode, polymer material such as poly (vinylcarbazole) (PVK) may be included. Furthermore, the composition may comprise a carrier promoter (such as electron promoter (including PBD (2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole)) or hole promoter (including TPD (N, N'-diphenyl-N, N '- (bis (3-methylphenyl) - [1,1-biphenyl; -4,4'-diamine)].

A detailed description will be given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be better understood by reading the following detailed description and examples with reference to the accompanying drawings. It shows:

1 a cross-section of an organic electroluminescent device disclosed by an embodiment of the disclosure. becomes.

MORE DETAILED DESCRIPTION

The following description is the best mode for carrying out the disclosure. This description is illustrative of the general principles of the disclosure and is not intended to be limiting consider. The determination of the scope of the disclosure is best made by reference to the appended claims.

The disclosure provides an organometallic compound prepared by introducing an alkyl group or cycloalkyl group for bonding with a 4-phenylthieno [3,2-c] pyridine moiety to increase their solubility. For example, a short chain alkyl group (such as methyl or ethyl) may be attached to a 4-phenylthieno [3,2-c] pyridine moiety, and the resulting organometallic compound would be suitable for use in a wet process or evaporation process. On the other hand, a long-chain alkyl group (such as tert-butyl or cyclohexyl) may be bonded to a 4-phenylthieno [3,2-c] pyridine moiety and the resulting organometallic compound would be suitable for use in a wet process. In addition, the organometallic compound of the disclosure can be used in an organic electroluminescent device to increase its efficiency.

Organometallic compound

worin R für eine Alkylgruppe oder Cycloalkylgruppe steht. So kann R beispielsweise für eine C_1-12-Alkylgruppe oder C_4-12-Cycloalkylgruppe stehen, wie Methyl, Ethyl, Propyl, Isopropyl, Butyl, Isobutyl, sec.-Butyl, tert.-Butyl, Pentyl, sec.-Pentyl, Cyclopentyl, Hexyl, Cyclohexyl, Heptyl, Octyl, Nonyl, Decyl, Hendecyl oder Dodecyl.The disclosure provides an organometallic compound having a structure represented by formula (I) or formula (II):

wherein R is an alkyl group or cycloalkyl group. Thus, R can be, for example, a C _1-12 -alkyl group or C _4-12 -cycloalkyl group, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, sec-pentyl , Cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, hendecyl or dodecyl.

The following examples are intended to illustrate the invention without limiting the scope, as numerous modifications and variations will be readily apparent to those skilled in the art.

example 1

Preparation of compound PO-01-M

To a 500 mL reaction flask was added 7.0 g of compound (1) (2- (2-aminoethyl) thiophene, 55.1 mmol) and 200 mL H ₂ O. Then, at 0 ° C, 11.0 mL of Compound (2) (p-toluoyl chloride, 82.7 mmol) was dropped into the reaction flask. Thereafter, an aqueous NaOH solution (20%) was added to the reaction flask and stirred overnight. After filtration, a compound (3) (white solid) was obtained in a yield of 93%. The synthetic route of the above reaction was as follows.

Thereafter, 5.0 g of compound (3) (20.4 mmol) and 80 mL of toluene were placed in a 250 mL reaction flask. Thereafter, 5.7 ml of POCl ₃ (61.2 mmol) were added dropwise to the reaction flask at 0 ° C. After stirring for 2 h under reflux, a saturated aqueous NaHCO ₃ solution was added to the reaction flask to quench the reaction. After toluene extraction, an organic layer was collected and dried with magnesium sulfate. After concentration, a compound (4) (crystal) was obtained in a yield of 50%. The synthetic route of the above reaction was as follows:

Thereafter, 3.0 g of compound (4) (13.2 mmol), 3.0 g of Pd / C (10%) and 100 ml of toluene were placed in a 250 ml reaction flask. After 18 hours at reflux, the result was filtered through Celite 545 to remove Pd / C. After concentrating the filtrate, a compound (5) was obtained in a yield of 85%. The synthetic route of the above reaction was as follows:

Thereafter, 5.0 g of compound (5) (22.2 mmol), 3.0 g of IrCl ₃ .xH ₂ O (10 mmol), 15 mL of 2-methoxyethanol and 5 mL of water were added to a 100 mL reaction flask. After 24 h of reaction, the reaction was quenched with water. After filtration, a compound (6) (orange solid) was obtained in 49% yield. The synthetic route of the above reaction was as follows:

Into a 100 mL reaction flask were added 3.3 g of Compound (6) (4.0 mmol), 1.65 g of acac (acetylacetone, 16 mmol), 1.71 g of Na ₂ CO ₃ (16 mmol) and 40 mL 2-Methoxyethanol given. After 24 h under reflux and cooling 40 mL of water are added to the reaction flask. After filtration and purification by column chromatography with methylene dichloride, a compound PO-01-M (orange powder) was obtained in a yield of 50%. The synthetic route of the above reaction was as follows:

The physical measurement of compound PO-01-M is listed below:
¹ H-NMR (CDCl ₃ , 200 MHz) δ 8.41 (d, J = 3.4 Hz, 2H), 8.34 (d, J = 5.6 Hz, 2H), 8.02 (d, J = 8.0 Hz, 2H), 7.66 (d, J = 5.6 Hz, 2H), 7.60 (d, J = 6.2 Hz, 2H), 6.69 (d, J = 7.6Hz, 2H), 6.15 (s, 2H), 5.18 (s, 1H), 2.03 (s, 6H), 1.75 (s, 6H).

Example 2

Preparation of compound PO-01-TB

To a 500 mL reaction flask was added 7.0 g Compound 1 (2- (2-aminoethyl) thiophene, 55.1 mmol) and 200 mL H ₂ O. Then, at 0 ° C, 16.2 g of Compound (7) (4-t-butylbenzoyl chloride, 82.5 mmol) was dropped into the reaction flask. Thereafter, an aqueous NaOH solution (20%) was added to the reaction flask and stirred overnight. After filtration, a compound (8) (white solid) was obtained in 98% yield. The synthetic route of the above reaction was as follows:

Thereafter, 2.87 g of Compound (8) (10 mmol) and 80 mL of toluene were added to a 250 mL reaction flask. Thereafter, 2.8 ml of POCl ₃ (61.2 mmol) were added dropwise to the reaction flask at 0 ° C. After stirring for 2 h under reflux, a saturated aqueous NaHCO ₃ solution was added to the reaction flask to quench the reaction. After toluene extraction, an organic layer was collected and dried with magnesium sulfate. After concentration, a compound (9) (crystal) was obtained in a yield of 60%. The synthetic route of the above reaction was as follows:

Thereafter, 2.7 g of Compound (9) (10 mmol), 0.5 g of Pd / C (10%) and 100 mL of toluene were placed in a 250 mL reaction flask. After 18 hours at reflux, the result was filtered through Celite 545 to remove Pd / C. After concentrating the filtrate and purifying by column chromatography with ethyl acetate and hexane (1: 9), a compound (10) was obtained in a yield of 79%. The synthetic route of the above reaction was as follows:

Thereafter, 5.0 g of Compound (10) (18.7 mmol), 2.9 g of IrCl ₃ .xH ₂ O (8.5 mmol), 15 mL of 2-methoxyethanol and 5 mL of water were placed in a 100 mL reaction flask given. After 24 h of reaction, the reaction was quenched with Nasser. After filtration, a compound (11) (orange solid) was obtained in 49% yield. The synthetic route of the above reaction was as follows:

Into a 100 mL reaction flask were added 1.48 g of compound (6) (1.5 mmol), 0.6 g of acac (acetylacetone, 6 mmol), 0.64 g of Na ₂ CO ₃ (6 mmol) and 15 mL 2-Methoxyethanol given. After heating for 24 h under reflux and cooling, 40 mL of water are added to the reaction flask. After filtration and purification by column chromatography with methylene dichloride, a compound PO-01-TB (orange powder) was obtained in a yield of 89%.

The synthetic route of the above reaction was as follows:

The physical measurement of compound PO-01-TB is shown below:
¹ H-NMR (CDCl ₃ , 200 MHz) δ 8.45 (d, J = 6.6 Hz, 2H), 8.30 (d, J = 5.4 Hz, 2H), 7.99 (d, J = 8.4Hz, 2H), 7.64 (d, J = 5.0Hz, 4H), 6.88 (dd, J = 8.6Hz, 1.8Hz, 2H), 6.22 (d, J = 1.8 Hz, 2H), 5.22 (s, 1H), 1.79 (s, 6H), 0.98 (s, 18H).

Example 3

Preparation of compound PO-01-HEX

To a 500 mL reaction flask was added 9.4 g of Compound (1) (2- (2-aminoethyl) thiophene, 74.1 mmol) and 200 mL H ₂ O. Then, at 0 ° C, 25.0 g of Compound (12) (4-n-hexylbenzoyl chloride, 111.2 mmol) was dropped into the reaction flask. Thereafter, an aqueous NaOH solution (20%) was added to the reaction flask and stirred overnight. After filtration, a compound (13) (white solid) was obtained in 88% yield. The synthetic route of the above reaction was as follows:

Next, 5.0 g of Compound (13) (15.9 mmol) and 80 mL of toluene were placed in a 250 mL reaction flask. Thereafter, 4.4 ml of POCl ₃ (47.6 mmol) were added dropwise to the reaction flask at 0 ° C. After stirring for 2 h under reflux, a saturated aqueous NaHCO ₃ solution was added to the reaction flask to quench the reaction. After toluene extraction, an organic layer was collected and dried with magnesium sulfate. After concentration, a compound (14) (crystal) was obtained in a yield of 55%. The synthetic route of the above reaction was as follows:

Thereafter, 3.0 g of compound (14) (13.2 mmol), 3.0 g of Pd / C (10%) and 100 ml of toluene were placed in a 250 ml reaction flask. After 18 hours at reflux, the result was filtered through Celite 545 to remove Pd / C. After concentration of the filtrate and purification by column chromatography with Ethyl acetate and hexane (1: 9), a compound (15) was obtained in a yield of 75%. The synthetic route of the above reaction was as follows:

Thereafter, 3.8 g of compound (5) (12.88 mmol), 1.7 g of IrCl ₃ .xH ₂ O (5.85 mmol), 15 mL of 2-methoxyethanol and 5 mL of water were placed in a 100 mL reaction flask given. After 24 h of reaction, the reaction was quenched with water. After filtration, a compound (16) (orange solid) was obtained in a yield of 40%. The synthetic route of the above reaction was as follows:

Into a 100 mL reaction flask, 5.0 g of Compound (6) (4.0 mmol), 1.23 g of acac (acetylacetone, 12.26 mmol), 1.30 g of Na ₂ CO ₃ (12.26 mmol ) and 30 mL of 2-methoxyethanol. After refluxing for 24 h and cooling, 40 mL of water was added to the reaction flask. After filtration and purification by column chromatography with methylene dichloride and hexane (1: 3), a compound PO-01-HEX (orange powder) was obtained in a yield of 63%. The synthetic route of the above reaction was as follows:

The physical measurement of compound PO-01-HEX is shown below:
¹ H-NMR (CDCl ₃ , 200 MHz) δ 8.42 (d, J = 3.4 Hz, 2H), 8.32 (d, J = 5.0 Hz, 2H), 8.01 (d, J = 5.0 Hz, 2H), 7.65 (d, = 5.4 Hz, 2H), 7.42 (d, J = 4.8 Hz, 2H), 6.69 (d, J = 7 , 6 Hz, 2H), 6.10 (s, 2H), 5.19 (s, 1H), 2.26 (t, J = 6.6 Hz, 4H), 1.76 (s, 6H), 1.55 (s, 4H), 1.10 (br, 12H), 0.80 (t, J = 7.2Hz, 6H).

Example 4

Solubility Test

aufweist und als Kontrollgruppe dient) wurden jeweils zur Herstellung von 0,5%igen, 0,8%igen, 1%igen, 1,5%igen, 2%igen und 3%igen Lösungen von metallorganischer Verbindung in Chlorbenzol gelöst, und der lösliche Grad der metallorganischen Verbindungen wurde beobachtet. Die Ergebnisse sind in Tabelle 1 gezeigt: 3% 2% 1,5% 1% 0,8% 0,5% PO-01 X X X X X O (ungefähr gelöst) PO-01-TB X X O O O O PO-01-HEX O O O O O O Tabelle 1 (X: unlöslich oder teilweise löslich, O: vollständig löslich)The compound PO-01-TB (Example 2), the compound PO-01-HEX (Example 3) and a compound PO-01 (containing the structure

and used as a control group) were each dissolved to produce 0.5%, 0.8%, 1%, 1.5%, 2% and 3% solutions of organometallic compound in chlorobenzene, and the soluble levels of organometallic compounds were observed. The results are shown in Table 1: 3% 2% 1.5% 1% 0.8% 0.5% PO-01 X X X X X O (about solved) PO-01-TB X X O O O O PO-01-HEX O O O O O O Table 1 (X: insoluble or partially soluble, O: completely soluble)

As shown in Table 1, the organometallic compounds having a 4-phenylthieno [3,2-c] pyridine unit bonded with a long-chain alkyl group or cycloalkyl group (such as PO-01-TB and PO-01-HE) had improved solubility (greater than 1.5% in chlorobenzene) compared to compound PO-01 (R is H, with a solubility of 0.5% in chlorobenzene).

Organic electroluminescent device

1 shows an embodiment of an organic electroluminescent device 10 , The electroluminescent device 100 includes a substrate 12 , a sub-electrode 14 , an electroluminescent element 16 and an upper electrode 18 , as in 1 shown. The organic electroluminescent device may be top-emission, bottom-emission, or dual-emission devices.

At the substrate 12 it can be a glass, plastic or semiconductor substrate. Suitable materials for the bottom and top electrodes may include Ca, Ag, Mg, Al, Li, In, Au, Ni, W, Pt, Cu, indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), or zinc oxide (ZnO). be formed by sputtering, electron beam evaporation, thermal evaporation or chemical vapor deposition. Furthermore, at least one of the lower and upper electrodes 14 and 18 transparent.

The electroluminescent element 16 contains at least one emission layer and may further include a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. In one embodiment of the disclosure, at least one layer of the electroluminescent element is included 16 the above listed organometallic compound.

According to an embodiment of the disclosure, the organic electroluminescent device may be a phosphorescent organic electroluminescent device, and the phosphorescent organic electroluminescent device may be an emission layer containing a host material and a phosphorescent dopant, wherein the host material comprises the above-listed organometallic compounds.

For the purpose of clearly disclosing the organic electroluminescent devices of the disclosure, the following examples (using the organometallic compounds of Examples 1-3 and evaporation or wet processes) and Comparative Examples are intended to illustrate the disclosure without limiting its scope, since numerous modifications and variations will be apparent to those skilled in the art Those skilled in the art are readily apparent.

dry process

Comparative Example 1

(das Verhältnis zwischen CBP und PO-01 betrug 100:6, mit einer Dicke von 30 nm) mit einer Dicke von 30 nm), BCP (2,9-Dimethyl-4,7-diphenyl-1,10-phenanthrolin, mit einer Dicke von 10 nm), Alq3 (Tris(8-hydroxychinolin)aluminium, mit einer Dicke von 20 nm), LiF (mit einer Dicke von 0,5 nm) und Al (mit einer Dicke von 120 nm) gebildet, was die elektrolumineszierende Vorrichtung (1) ergab. Die Materialien und daraus gebildeten Schichten sind im folgenden beschrieben:
ITO/NPB/CBP: PO-01 (6%)/BCP/Alq3/LiF/AlA glass substrate with a film of indium tin oxide (ITO) having a thickness of 120 nm was provided and then washed with a detergent, acetone and isopropanol under ultrasonic treatment. After drying with a stream of nitrogen, the ITO film was subjected to a UV / ozone treatment. Thereafter, on the ITO film, at 10-6 Pa, NPB (N, N'-di (naphthalen-1-yl) -N, N'-diphenylbenzidine, having a thickness of 30 nm), CBP (4.4 '-N, N'-dicarbazolebiphenyl) doped with PO-01

(the ratio between CBP and PO-01 was 100: 6, with a thickness of 30 nm) with a thickness of 30 nm), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, with a thickness of 10 nm), Alq3 (tris (8-hydroxyquinoline) aluminum, having a thickness of 20 nm), LiF (having a thickness of 0.5 nm) and Al (having a thickness of 120 nm), which is the electroluminescent device (1). The materials and layers formed therefrom are described below:
ITO / NPB / CBP: PO-01 (6%) / BCP / Alq3 / LiF / Al

The optical properties of the electroluminescent device (1) according to Comparative Example 1 were measured with a PR650 type device (from Photo Reseach Inc.) and a Minolta TS110 type device. The results are shown in Table 2.

Example 5

(das Verhältnis zwischen GBP und PO-01-TB betrug 100:6, mit einer Dicke von 30 nm) mit einer Dicke von 30 nm), BCP (2,9-Dimethyl-4,7-diphenyl-1,10-phenanthrolin, mit einer Dicke von 10 nm), Alq3 (Tris(8-hydroxychinolin)aluminium, mit einer Dicke von 20 nm), LiF (mit einer Dicke von 0,5 nm) und Al (mit einer Dicke von 120 nm) gebildet, was die elektroumineszierende Vorrichtung (2) ergab. Die Materialien und daraus gebildeten Schichten sind im folgenden beschrieben:
ITO/NPB/CBP: PO-01-TB (6%)/BCP/Alq3/LiF/AlA glass substrate with a film of indium tin oxide (ITO) having a thickness of 120 nm was provided and then washed with a detergent, acetone and isopropanol under ultrasonic treatment. After drying with a stream of nitrogen, the ITO film was subjected to a UV / ozone treatment. Thereafter, on the ITO film, at 10-6 Pa, NPB (N, N'-di (naphthalen-1-yl) -N, N'-diphenylbenzidine, having a thickness of 30 nm), CBP (4.4 '-N, N'-dicarbazolebiphenyl) doped with PO-01

(the ratio between GBP and PO-01-TB was 100: 6, with a thickness of 30 nm) with a thickness of 30 nm), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline , with a thickness of 10 nm), Alq3 (tris (8-hydroxyquinoline) aluminum, with a thickness of 20 nm), LiF (with a thickness of 0.5 nm) and Al (with a thickness of 120 nm), resulting in the electro-luminescent device (2). The materials and layers formed therefrom are described below:
ITO / NPB / CBP: PO-01-TB (6%) / BCP / Alq3 / LiF / Al

The optical properties of the electroluminescent device (2) according to Example 5 were measured with a PR650 device (from Photo Reseach Inc.) and a Minolta TS110 device. The results are shown in Table 2. Driver voltage (V) Electricity efficiency (cd / A) CIE (X, Y) Wavelength (nm) electroluminescent device (1) 5.2 40.3 (0.48, 0.50) 560 electroluminescent device (2) 4.1 62.8 (0.48, 0.51) 560 Table 2

As shown in Table 2, provided that the same host material was used, the organometallic compound PO-01-TB of the disclosure showed better efficiency and reduced stress in comparison with the compound PO-01 according to Comparative Example 1.

wet

Comparative Example 2:

A glass substrate with a film of indium tin oxide (ITO) having a thickness of 120 nm was provided and then washed with a detergent, acetone and isopropanol under ultrasonic treatment. After drying with a stream of nitrogen, the ITO film was subjected to a UV / ozone treatment. Thereafter, PEDOT (poly (3,4-ethylenedioxythiophene): PSS (e-polystyrenesulfonate) was applied on the ITO film by means of a knife coating and spin coating method (at a rotation rate of 4000 rpm) and 40 minutes at 100 ° C fired to form a PEDO: PSS film (having a thickness of 50 nm, serving as a hole injection layer). Thereafter, using a knife coating method, TFB (poly [99.9-dioctylfluorenyl-2,7-diyl) -co- (4,4 '- (N- (4-s-butylphenyl)) diphenylamine)]) was added to the PEDO: PSS film was applied and fired at 100 ° C. for 40 minutes to form a TFB film (having a thickness of 20 nm, serving as a hole transport layer). Thereafter, a PVK (poly (vinylcarbazole)), PBD (2- (p.p. 4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole), TPD (N, N'-diphenyl-N, N '- (bis (3-methylphenyl) - [1, 1-biphenyl] -4,4'-diamine) and PO-01 (the weight ratio of PVK: PBD: TP-01 is 55: 34: 9: 6, dissolved in chlorobenzene) containing composition after a knife coating and Spin-coating method is applied to the TFB film to form a light-emitting film (having a thickness of 30 nm). Thereafter, TPBI (1,3,5-tris (phenyl-2-benzimidazolyl) benzene) was applied to the PEDO: PSS film by a knife coating and spin coating method and baked at 100 ° C for 40 minutes to obtain a TPBI film (with a thickness of 20 nm, serves as a hole blocking / electron transport layer). Thereafter, LiF (having a thickness of 0.5 nm) and Al (having a thickness of 120 nm) were subsequently formed at 10-6 Pa on the TPBI film, yielding the electroluminescent device (3). The materials and layers formed therefrom are described below:
ITO / PEDOT (CH8000) / TFB / PVK: PBD: T2D: PO-01 / TPBI / LiF / Al

The optical properties of the electroluminescent device (3) according to Comparative Example 2 were measured with a PR650 type device (from Photo Reseach Inc.) and a Minolta TS110 type device. The results are shown in Table 3.

Example 6:

A glass substrate with a film of indium tin oxide (ITO) having a thickness of 120 nm was provided and then washed with a detergent, acetone and isopropanol under ultrasonic treatment. After drying with a stream of nitrogen, the ITO film was subjected to a UV / ozone treatment. Thereafter, PEDOT (poly (3,4) ethylenedioxythiophene): PSS (e-polystyrenesulfonate) was applied on the ITO film by means of a knife coating and spin coating method (at a rotation rate of 4000 rpm) and Fired at 100 ° C for 40 minutes to form a PEDO: PSS film (having a thickness of 50 nm, serving as a hole injection layer). Thereafter, using a knife coating method, TFB (poly [99.9-dioctylfluorenyl-2,7-diyl) -co- (4,4 '- (N- (4-s-butylphenyl)) diphenylamine)]) was added to the PEDO: PSS film was applied and fired at 100 ° C for 40 minutes to form a TFB film (having a thickness of 20 nm, serving as a hole transporting layer). Thereafter, a PVK (poly (vinylcarbazole)), PBD (2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole), TPD (N, N'-diphenyl) N, N '- (bis (3-methylphenyl) - [1,1-biphenyl] -4,4'-diamine)) and PO-01-TB (the weight ratio of PVK: PBD: TPD: PO-01-TB 61: 24: 9: 6 dissolved in chlorobenzene) composition was applied to the TFB film by a knife coating and spin coating method to form a light emitting film (having a thickness of 30 nm). Thereafter, TPBI (1,3,5-tris (phenyl-2-benzimidazolyl) benzene) was applied to the PEDO: PSS film by a knife coating and spin coating method and baked at 100 ° C for 40 minutes to obtain a TPBI film (with a thickness of 20 nm, serves as a hole blocking / electron transport layer). Thereafter, LiF (having a thickness of 0.5 nm) and Al (having a thickness of 120 nm) were subsequently formed at 10-6 Pa on the TPBI film, yielding the electroluminescent device (4). The materials and layers formed therefrom are described below:
ITO / PEDOT (CH8000) / TFB / PVK: PBD: TPD: PO-01-TB / TPBI / LiF / Al

The optical properties of the electroluminescent device (4) according to Example 6 were measured with a PR650 device (from Photo Reseach Inc.) and a Minolta TS110 device. The results are shown in Table 3.

Example 7:

A glass substrate with a film of indium tin oxide (ITO) having a thickness of 120 nm was provided and then washed with a detergent, acetone and isopropanol under ultrasonic treatment. After drying with a stream of nitrogen, the ITO film was subjected to a UV / ozone treatment. Thereafter, PEDOT (poly (3,4-ethylenedioxythiophene): PSS (e-polystyrenesulfonate) was applied on the ITO film by means of a knife coating and spin coating method (at a rotation rate of 4000 rpm) and 40 minutes at 100 ° C fired to form a PEDO: PSS film (having a thickness of 50 nm, serving as a hole injection layer). TEE (poly [99.9-dioctylfluorenyl-2,7-diyl) -co- (4,4'-N- (4-s-butylphenyl)) -diphenylamine)]) was then applied to the PEDO: PSS by a knife coating method Film was applied and baked at 100 ° C for 40 minutes to form a TFB film (having a thickness of 20 nm, serving as a hole transporting layer). Thereafter, a PVK (poly (vinylcarbazole)), PBD (2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole), TPD (N, N'-diphenyl) N, N '- (bis (3-methylphenyl) - [1,1-biphenyl] -4,4'-diamine)) and PO-01-HEX (the weight ratio of PVK: PBD: TPD: PO-01-HEX 61: 24: 9: 6 dissolved in chlorobenzene) composition was applied to the TFB film by a knife coating and spin coating method to form a light emitting film (having a thickness of 30 nm). Thereafter, TPBI (1,3,5-tris (phenyl-2-benzimidazolyl) benzene) was applied to the PEDO: PSS film by a knife coating and spin coating method and baked at 100 ° C for 40 minutes to obtain a TPBI film (with a thickness of 20 nm, serves as a hole blocking / electron transport layer). Thereafter, LiF (having a thickness of 0.5 nm) and Al (having a thickness of 120 nm) were subsequently formed at 10-6 Pa on the TPBI film, yielding the electroluminescent device (5).

The materials and layers formed therefrom are described below:
ITO / PEDOT (CH8000) / TFB / PVK: PBD: TPD: PO-01-HEX / TPBI / LiF / Al

The optical properties of the electroluminescent device (5) according to Example 7 were measured with a PR650 device (from Photo Reseach Inc.) and a Minolta TS110 device. The results are shown in Table 3. Efficiency (cd / A) CIE (X, Y) Wavelength (nm) electroluminescent device (3) 2.7 (0.49, 0.50) 560 electroluminescent device (4) 35 (0.48, 0.51) 560 electroluminescent device (5) 20 (0.47, 0.52) 558 Table 3

As shown in Table 3, provided that the same host material and the same wet method were used, the organometallic compounds PO-01-TB and PO-01-HEX according to the disclosure showed better efficiency as compared with the compound PO-01 according to Comparative Example 2, which is due to the improved solubility.

While the disclosure has been described by way of examples and the preferred embodiments, it should be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, various modifications and similar arrangements are intended to be covered (as would be readily apparent to one skilled in the art). Therefore, the scope of the appended claims should be subjected to the most general interpretation so that all such modifications and similar arrangements are included.

Claims (10)

Organometallic compound of the formula (I) or formula (II):

wherein R is an alkyl group or cycloalkyl group. The organometallic compound of claim 1, wherein R is a C _1-12 alkyl group or C _4-12 cycloalkyl group. Organometallic compound according to Claim 1, in which R represents methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, sec-pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, Decyl, hendecyl or dodecyl. An organic electroluminescent device comprising: a pair of electrodes and an electroluminescent element disposed between the pair of electrodes, wherein the electroluminescent element is the organometallic compound of the formula (I) or (II):

wherein R represents an alkyl group or cycloalkyl group. The organic electroluminescent device of claim 4, wherein R is a C _1-12 alkyl group or C _4-12 cycloalkyl group. An organic electroluminescent device according to claim 4, wherein R is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, sec-pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, Decyl, hendecyl or dodecyl. The organic electroluminescent device according to claim 4, wherein the electroluminescent element is produced by an evaporation method. The organic electroluminescent device according to claim 4, wherein the electroluminescent element is produced by a wet process. The organic electroluminescent device of claim 4, wherein the electroluminescent element emits orange light under a bias voltage. A composition comprising: an organic electroluminescent host material and an organometallic compound of formula (I) or (II):

wherein R is an alkyl group or cycloalkyl group.

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