Organic metal iridium complex, preparation method thereof, luminescent material and organic electroluminescent device

Abstract

The invention relates to the technical field of organic electroluminescent devices, in particular to an organic metal iridium complex, a preparation method of the organic metal iridium complex, a luminescent material and an organic electroluminescent device. The organic metal iridium complex is selected from a compound shown in the following structural formula: # imgabs0 #, wherein R1 to R14 are respectively and independently selected from any one of hydrogen, deuterium, tritium, halogen, cyano, trimethyl silicon, trimethyl germanium, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted 4-membered to 8-membered heterocyclic radical; the number of R10 on a benzene ring of dibenzofuran in the formula 1 is 1 or 2; s1 is selected from substituted or unsubstituted dibenzofuran, and S1 is fused with any position on a benzene ring of adjacent dibenzofuran. The organic metal iridium complex is low in synthesis cost, simple in synthesis process and difficult to purify, and an organic electroluminescent device formed by the organic metal iridium complex is high in luminous efficiency, long in service life and low in driving voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescent devices, and in particular to an organic metal iridium complex and a preparation method thereof, a luminescent material and an organic electroluminescent device. Background Art

[0002] With the increasing demand for color and quality in mobile phones, TVs, computers, and other related screens, research on OLEDs has made significant progress over the past few decades. This is because compared to other lighting sources, OLEDs can emit light directly from the surface, allowing for customized shapes and achieving the same luminous flux at reduced light intensity, making them highly efficient.

[0003] In 1998, Forrest et al. at Princeton University discovered that when the phosphorescent dye octaethylporphyrin platinum was doped into a host luminescent material, the resulting light-emitting device had an external quantum efficiency of 4% and an internal quantum efficiency of 23%. This opened up a new field of phosphorescent electroluminescence, and organic electrophosphorescence experienced rapid development in the following years. When used as phosphorescent materials, noble metal complexes fully utilize both singlet and triplet excitons. Compared to fluorescent materials that only utilize singlet excitons, their triplet exciton utilization rate is as high as 75%, enabling phosphorescent-based PhOLEDs to achieve 100% internal quantum efficiency. Consequently, in recent years, researchers have devoted significant research to the study of heavy metal-coordinated organic fluorescent materials, particularly those based on iridium complexes.

[0004] However, current research indicates that the synthesis cost of metal iridium complex organic fluorescent materials is relatively high, the synthesis process is complex, and purification is difficult during the synthesis process. This leads to shortcomings such as short lifespan and low efficiency in the resulting organic electroluminescent devices. Therefore, developing a material that can achieve high luminous efficiency and long device life is an urgent issue.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The present invention aims to provide an organometallic iridium complex, a preparation method thereof, a luminescent material, and an organic electroluminescent device. The organometallic iridium complex has low synthesis cost, a simple synthesis process, and is difficult to purify. Furthermore, the organic electroluminescent device formed from the organometallic iridium complex has high luminous efficiency, a long life, and a low driving voltage.

[0007] The present invention is achieved in that:

[0008] In a first aspect, an embodiment of the present invention provides an organometallic iridium complex selected from the compounds represented by the following structural formula:

[0009] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 and R 14 Each is independently selected from any one of hydrogen, deuterium, tritium, halogen, cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted 4-8 membered heterocyclyl;

[0010] R on the benzene ring of dibenzofuran in formula 1 10 The number of is 1 or 2;

[0011] S1 is selected from substituted or unsubstituted dibenzofuran, and S1 is fused to any position on the benzene ring of the adjacent dibenzofuran.

[0012] In a second aspect, an embodiment of the present invention provides a method for preparing an organometallic iridium complex, comprising synthesizing according to the following synthesis path:

[0013]

[0014] Preferably, the process comprises: mixing raw material LA and iridium trichloride trihydrate under an inert gas atmosphere at 100-120° C. and reacting for 40-55 hours to form intermediate L-A1;

[0015] Under an inert gas atmosphere, the intermediate L-A1 and silver trifluoromethanesulfonate are mixed at 20-35° C. and reacted for 40-55 hours to form the intermediate L-A2;

[0016] Under an inert gas atmosphere, the intermediate L-A2 and LB were mixed and reacted at 80-100° C. for 40-55 hours.

[0017] In a third aspect, an embodiment of the present invention provides a light-emitting material comprising the aforementioned organometallic iridium complex.

[0018] In a fourth aspect, an embodiment of the present invention provides an organic electroluminescent device, which includes a light-emitting layer formed of the aforementioned light-emitting material.

[0019] The present invention has the following beneficial effects: After the complex provided by the embodiments of the present invention is fused with dibenzofuran, its dipole moment increases, enhancing the charge separation tendency within the molecule or at the interface, reducing the exciton binding energy, thereby promoting charge dissociation and transfer efficiency, and thus reducing the driving voltage. Application of the complex in an electroluminescent device significantly reduces the driving voltage, and the lifetime and luminous efficiency are also correspondingly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is the NMR spectrum of the organometallic iridium complex L-13 provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0023] An embodiment of the present invention provides an organometallic iridium complex selected from the compounds represented by the following structural formula:

[0024] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 and R 14 Each is independently selected from any one of hydrogen, deuterium, tritium, halogen, cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted 4-8 membered heterocyclic group; for example, each is independently selected from any one of hydrogen, deuterium, tritium, fluorine, cyano, -CH3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, -CD3 and the groups represented by the following structural formula:

[0025] Among them, * represents the replacement position.

[0026] Wherein, R on the benzene ring of dibenzofuran in Formula 1 10 The number of is 1 or 2. If R 10 The number of is 2, at this time 2 R 10 They can be the same or different.

[0027] S1 is selected from substituted or unsubstituted dibenzofuran, and S1 is fused to any position on the benzene ring of the adjacent dibenzofuran. If S1 is selected from substituted dibenzofuran, the substituent group may be at least one selected from halogen, cyano, substituted or unsubstituted C1-C10 alkyl, and substituted or unsubstituted C3-C8 cycloalkyl. For example, it may be selected from at least one selected from fluorine, cyano, methyl, tert-butyl, and the group represented by the following structural formula: Wherein, * represents the substitution position, and the number of substituents can be 1, 2 or 3.

[0028] It should be noted that the C1-C10 alkyl groups described in the embodiments of the present invention may include unsubstituted C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, and isopentyl, and may also be substituted C1-C10 alkyl groups in which at least one hydrogen on at least one carbon in the unsubstituted C1-C10 alkyl groups is replaced by a halogen, cyano, hydroxyl, or alkoxy group. Examples of the embodiments of the present invention include the following: for example, one hydrogen, two hydrogens, or three hydrogens on one carbon are replaced, or one hydrogen on each of two carbons is replaced, two hydrogens on one of two carbons are replaced, or one hydrogen on one carbon is replaced.

[0029] Similarly, the substituted or unsubstituted C3-C8 cycloalkyl groups provided in the embodiments of the present invention include unsubstituted cycloalkanes such as cyclopropane, cyclobutane, cyclohexane, and cyclopentane, and may also be substituted C3-C8 cycloalkyl groups in which one or more hydrogen atoms in the above cycloalkanes are replaced.

[0030] Similarly, the substituted or unsubstituted C6-C20 aryl groups provided in the embodiments of the present invention include aromatic groups such as phenyl, biphenyl, and terphenyl, and may also be aryl groups in which one or more hydrogen atoms are substituted.

[0031] Similarly, the substituted or unsubstituted 4-membered to 8-membered heterocyclic groups provided in the embodiments of the present invention include furan, tetrahydrofuran, pyridine, piperidine, thiopheneethylthiazole and other heterocyclic groups.

[0032] Furthermore, the ligand A in Formula 1 is selected from any one of LA-1 to LA-100 represented by the following structural formula:

[0033]

[0034]

[0035]

[0036]

[0037] Furthermore, the organometallic iridium complex is selected from any one of the compounds represented by the following structural formulas:

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] The embodiments of the present invention form an extended π-electron system through furan conjugation, thereby improving the photoelectric performance. Due to the presence of the furan ring, the molecular rigidity and thermal stability are enhanced. The addition of dibenzofuran to the benzofuran ring suppresses the quenching effect caused by intermolecular aggregation, thereby improving the luminous efficiency, lifespan and driving voltage of the organic electroluminescent device.

[0060] In a second aspect, an embodiment of the present invention provides a method for preparing an organometallic iridium complex, comprising: synthesizing according to the following synthesis path:

[0061]

[0062] The specific operation is as follows: Step 1: Under an inert gas atmosphere, the raw materials LA and iridium trichloride trihydrate are mixed and reacted at 100-120°C for 40-55 hours to form intermediate L-A1. Specifically, the raw materials LA, iridium trichloride trihydrate, an alcohol ether solvent (e.g., ethylene glycol ethyl ether), and water are added under nitrogen conditions, reacted at 100-120°C for 40-55 hours, and then filtered, rinsed with ethanol and petroleum ether, and dried to obtain intermediate L-A1.

[0063] Step 2: Under an inert gas atmosphere, the intermediate L-A1 and silver trifluoromethanesulfonate are mixed and reacted at 20-35°C for 40-55 hours to form intermediate L-A2. Specifically, intermediate L-A1, silver trifluoromethanesulfonate, an alcohol solvent (e.g., isopropyl alcohol), and a chloroalkane (e.g., dichloromethane) are added under nitrogen, reacted at 20-35°C for 40-55 hours, and then passed through a silica gel funnel and rinsed with dichloromethane until no product is present. The organic phases are combined and spin-dried to obtain intermediate L-A2.

[0064] Under an inert gas atmosphere, the intermediate L-A2 and LB are mixed at 80-100° C. and reacted for 40-55 hours. Specifically, the intermediate L-A2, LB, and an alcohol solvent (e.g., ethanol) are added under nitrogen and reacted at 80-100° C. for 40-55 hours, followed by filtration and column chromatography to obtain product L.

[0065] In a third aspect, an embodiment of the present invention provides a light-emitting material comprising the aforementioned organometallic iridium complex.

[0066] In a fourth aspect, an embodiment of the present invention provides an organic electroluminescent device, which includes a light-emitting layer formed of the aforementioned light-emitting material.

[0067] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0068] Example 1

[0069] An embodiment of the present invention provides a method for preparing an organometallic iridium complex, comprising:

[0070]

[0071] Step 1: Under nitrogen, weigh raw material A-13 (CAS No. 582-17-2, 625 mmol), 1.5 L of chloroform, and 600 mL of acetic acid and stir for 5 minutes. Add NBS (635 mmol) and stir at room temperature for 2 hours. Add saturated brine (700 mL) and column chromatography to obtain intermediate B-13 (120 g, 81% yield). HPLC purity: >99.0%.

[0072]

[0073] Step 2: Under nitrogen, weigh intermediate B-13 (502 mmol), raw material C-13 (CAS No.: 1993-03-9502 mmol), tetrakistriphenylphosphine palladium (5 mmol), potassium carbonate (1.5 mol), tetrahydrofuran (1.2 L), and water (600 mL) and react at 90°C for 24 h. Separate the mixture and spin dry the mixture to obtain intermediate D-13 (72 g, 57% yield). HPLC purity: >99.0%

[0074] Step 3: Under nitrogen, weigh intermediate D-13 (283 mmol), potassium phosphate (0.85 mol), xylene 720 mL, and dimethylformamide 360 mL. Reflux for 12 h. Spin dry, filter through a funnel, and recrystallize to obtain intermediate E-181 (37 g, 52% yield). HPLC purity: >99.0%

[0075] The second and third steps refer to patent KR1020170096769A.

[0076]

[0077] Step 4: Under nitrogen conditions, weigh intermediate E-13 (158 mmol), F-13 (CAS No.: 883499-24-9158 mmol), potassium carbonate (237 mmol), and 560 mL of N-N-dimethylformamide, react at 140°C for 12 h; add water and ethanol, filter and recrystallize to obtain intermediate G-13 (34 g, yield 52%).

[0078] HPLC purity:>99.0%

[0079] Step 5: Under nitrogen, weigh intermediate G-13 (80.1 mmol), 340 mL of N-N-dimethylformamide, palladium acetate (1.6 mmol), and tricyclohexylphosphine (1.7 mmol), and react at 120°C for 12 h; add water and ethanol, column chromatography, and recrystallize to obtain 19 g of intermediate H-13 (yield 56%).

[0080] Step 4 and step 5 refer to patent CN113121584A.

[0081]

[0082] Step 6: Under nitrogen, intermediate H-13 (55 mmol), I-13 (CAS No. 852362-24-482.9 mmol), tetrakistriphenylphosphine palladium (1.1 mmol), 190 mL of toluene, 190 mL of ethanol, 95 mL of water, and potassium carbonate (166 mmol) were weighed and reacted at 90°C for 24 h. The mixture was separated and dried by spin drying. Column chromatography afforded intermediate J-13 (14.9 g, 70% yield). HPLC purity: >99.0%.

[0083]

[0084] Step 7: Under nitrogen, weigh the raw material J-13.-1 (CAS No.: 1008-89-5 96.6 mmol), iridium trichloride (32.2 mmol), ethylene glycol ethyl ether 220 mL, and water 73 mL, react at 120°C for 48 h, filter and rinse, and dry to obtain the intermediate J-13-2 (14.1 g, yield 82%).

[0085] Step 8: Under nitrogen conditions, weigh the raw material J-13-2 (11.2 mmol), silver trifluoromethanesulfonate (24.6 mmol), 240 mL of dichloromethane, and 60 mL of isopropanol, react at 25°C for 48 h, pass through a silica gel funnel, and spin dry to obtain the intermediate J-13-3 (12.9 g, yield 81%).

[0086]

[0087] Step 9: Under nitrogen, weigh the raw materials J-13-3 (14.5 mmol), J-13 (36 mmol), and 220 mL of ethanol, react at 90°C for 48 h, and filter and column chromatograph to obtain the final product L-13 (8.36 g, 65% yield). HPLC purity: >99.3%. Mass spectrum: assay value 886.23. Specifically, the NMR spectrum of the product L-13 can be found at Figure 1 .

[0088] Device Example 1

[0089] Device Example 1 provides an organic electroluminescent device. The light-emitting layer of the organic electroluminescent device is prepared by the product L-13 of Example 1 above. Specifically, the preparation method of the organic electroluminescent device is as follows:

[0090] The ITO glass substrate with a coating thickness of 1500 was cleaned twice in distilled water and ultrasonically washed for 30 minutes. After the distilled water washing was completed, it was ultrasonically washed in sequence with isopropyl alcohol, acetone, methanol and other solvents, and then dried. It was transferred to a plasma cleaning machine, washed for 5 minutes, and sent to a vapor deposition machine.

[0091] First, 4,4',4"-tris[2-naphthylphenylamino]triphenylamine ("2-TNATA") with a thickness of 100 Å was evaporated on the ITO (anode) as a hole injection layer, and then N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (i.e., NPB) with a thickness of 900 Å was evaporated on the hole injection layer as a hole transport layer. Then, a light-emitting layer with a weight ratio of 90:10 of the host material 4,4'-N,N'-biphenyldicarbazole ("CBP") and the dopant material (compound formula L-13 provided in Example 1) was evaporated with a thickness of 400 Å. Then, ALq3 with a thickness of 400 Å was evaporated on the light-emitting layer as an electron transport layer. Then, Liq with a thickness of 150 Å was evaporated on the electron transport layer. Finally, Al, a cathode material, with a thickness of 1000 Å was evaporated on the electron injection layer to obtain an organic electroluminescent device.

[0092] Device Example 2-12: The organic electroluminescent device provided in Device Example 2-12 is prepared according to the preparation method provided in Device Example 1, with the only difference being that L-13 is changed to L-18, L-23, L-35, L-46, L-56, L-76, L-83, L-164, L-175, L-228, L-298, or L-338.

[0093] Comparative Device Examples 1-6: Organic electroluminescent devices provided in Comparative Device Examples 1-6 were prepared according to the preparation method provided in Device Example 1, with the only difference being that L-13 was replaced with a compound represented by the following structural formula:

[0094]

[0095] The driving voltage, luminous efficiency, and lifespan of the organic electroluminescent devices obtained from the above-mentioned device examples 1-13 and device comparative examples 1-6 were characterized at a brightness of 15,000 nits. The test results are shown in Table 1 below. (The test results are normalized to those of Comparative Example 1):

[0096] Table 1 Test results

[0097]

[0098]

[0099] According to Table 1, by comparing with Comparative Example 1 and 2, it can be seen that the compound provided by the embodiment of the present invention increases the π electron system that furan ring forms expansion by conjugation, improves photoelectric performance, due to the presence of furan ring, molecular rigidity and thermal stability are enhanced. The compound provided by the embodiment of the present invention is compared with Comparative Example 3 simultaneously, it can be seen that increasing dibenzofuran on benzofuran ring suppresses the quenching effect caused by intermolecular aggregation, while improving the thermal stability of material, making the organic electroluminescent device prepared by the compound provided by the embodiment of the present invention as light-emitting layer doping material compared with the organic electroluminescent device prepared by Comparative Example, driving voltage is significantly reduced, and luminous efficiency and life-span are significantly improved. By embodiment 9,10 and 12 and Comparative Example 5,6 and 4 comparison, it can be seen that increasing dibenzofuran is little compared to benzofuran luminous efficiency and device life gain but because of its dipole moment increase, the charge separation tendency enhancement at intramolecular or interface reduces exciton binding energy, thereby promoting charge dissociation and transmission efficiency and then reducing driving voltage.

[0100] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An organometallic iridium complex, characterized in that It is selected from the compounds represented by the following structural formula: Ligand A Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 and R 14 Each is independently selected from any one of hydrogen, deuterium, tritium, halogen, cyano, trimethylsilyl, trimethylgermanium, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C20 aryl and substituted or unsubstituted 4-8 membered heterocyclic group; R on the benzene ring of dibenzofuran in formula 1 10 The number of is 1 or 2; S1 is selected from substituted or unsubstituted dibenzofuran, and S1 is fused to any position on the benzene ring of the adjacent dibenzofuran.

2. The organometallic iridium complex according to claim 1, characterized in that R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 and R 14 Each is independently selected from hydrogen, deuterium, tritium, fluorine, cyano, -CH3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, -CD3 and any one of the groups represented by the following structural formula: Among them, * represents the replacement position.

3. The organometallic iridium complex according to claim 1 or 2, characterized in that The number of substituents on the dibenzofuran in S1 is 1, 2, or 3.

4. The organometallic iridium complex according to claim 1 or 2, characterized in that The substituent of the dibenzofuran of S1 is selected from at least one of halogen, cyano, substituted or unsubstituted C1-C10 alkyl, and substituted or unsubstituted C3-C8 cycloalkyl.

5. The organometallic iridium complex according to claim 1 or 2, characterized in that The substituent of the dibenzofuran in S1 is selected from at least one of fluorine, cyano, methyl, tert-butyl and the groups represented by the following structural formula: Among them, * represents the replacement position.

6. The organometallic iridium complex according to claim 1 or 2, characterized in that The ligand A in Formula 1 is selected from any one of LA-1 to LA-100 shown in the following structural formula:

7. The organometallic iridium complex according to claim 1, characterized in that The organometallic iridium complex is selected from any one of the compounds represented by the following structural formulas:

8. A method for preparing the organometallic iridium complex according to claim 1, characterized in that: include: The synthesis was carried out according to the following synthesis route: Preferably, the process comprises: mixing raw material LA and iridium trichloride trihydrate under an inert gas atmosphere at 100-120° C. and reacting for 40-55 hours to form intermediate L-A1; Under an inert gas atmosphere, the intermediate L-A1 and silver trifluoromethanesulfonate are mixed at 20-35° C. and reacted for 40-55 hours to form the intermediate L-A2; Under an inert gas atmosphere, the intermediate L-A2 and LB were mixed and reacted at 80-100° C. for 40-55 hours.

9. A luminescent material, characterized in that: The invention comprises the organometallic iridium complex according to any one of claims 1 to 7.

10. An organic electroluminescent device, characterized in that: It comprises a light-emitting layer formed of the light-emitting material according to claim 9.

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