Organometallic iridium complexes, methods for their preparation, luminescent materials and organic electroluminescent devices

Abstract

The present application relates to the technical field of organic electroluminescence devices, in particular to an organic metal iridium complex, a preparation method thereof, a luminescent material and an organic electroluminescence device. 14 each independently is selected from any one of hydrogen, deuterium, tritium, halogen, cyano, trimethylsilane, trimethylgermane, 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; the number of R 10 on the benzene ring of dibenzofuran in formula 1 is 1 or 2; S1 is selected from substituted or unsubstituted dibenzofuran, and S1 is fused with any position on the benzene ring of the adjacent dibenzofuran. The organic metal iridium complex has low synthesis cost, simple synthesis process and difficult purification, and the organic electroluminescence device formed by the organic metal iridium complex has high luminous efficiency, long service life and low driving voltage.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescent devices, and more specifically, to organometallic iridium complexes and their preparation methods, luminescent materials, and organic electroluminescent devices. Background Technology

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

[0003] In 1998, Forrest et al. at Princeton University discovered that doping the phosphorescent dye octaethylporphyrin platinum into the host luminescent material resulted in a light-emitting device with an external quantum efficiency of 4% and an internal quantum efficiency of 23%. This discovery opened up a new field of phosphorescent electroluminescence, and organic electrophosphorescence developed rapidly in the following years. Noble metal complexes, when used as phosphorescent materials, fully utilize both singlet and triplet excitons, unlike fluorescent materials which only utilize singlet excitons. Their effective utilization rate of triplet excitons is as high as 75%, enabling PhOLEDs based on phosphorescent materials to achieve 100% internal quantum efficiency. Therefore, in recent years, researchers have focused on the study of heavy metal-coordinated organic fluorescent materials, especially iridium metal complexes.

[0004] However, current research indicates that the synthesis of iridium complex organic fluorescent materials is costly, requires complex processes, and faces challenges in purification. Furthermore, the resulting organic electroluminescent devices suffer from short lifespans and low efficiency. Therefore, developing a material that enables devices with high luminous efficiency and long lifespan is a pressing issue.

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

[0006] The purpose of this invention is to provide organometallic iridium complexes, their preparation methods, luminescent materials, and organic electroluminescent devices. These organometallic iridium complexes have low synthesis costs, simple synthesis processes, and are difficult to purify. Furthermore, the organic electroluminescent devices formed from these organometallic iridium complexes exhibit high luminous efficiency, long lifetime, and low driving voltage.

[0007] This invention is implemented as follows:

[0008] In a first aspect, embodiments of the present invention provide an organometallic iridium complex selected from compounds shown in the following structural formulas:

[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 heterocyclic groups;

[0010] In Formula 1, R on the benzene ring of dibenzofuran 10 The number of them is 1 or 2;

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

[0012] Secondly, embodiments of the present invention provide a method for preparing an organometallic iridium complex, comprising synthesis according to the following synthetic route:

[0013]

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

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

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

[0017] Thirdly, embodiments of the present invention provide a luminescent material comprising the aforementioned organometallic iridium complex.

[0018] Fourthly, embodiments of the present invention provide an organic electroluminescent device, which includes a light-emitting layer formed from the aforementioned light-emitting material.

[0019] The present invention has the following beneficial effects: The increased dipole moment of the complex fused with dibenzofuran provided in the embodiments of the present invention enhances the tendency for charge separation within the molecule or at the interface, reducing the exciton binding energy, thereby promoting charge dissociation and transport efficiency, and thus reducing the driving voltage. When applied to electroluminescent devices, the driving voltage is significantly reduced. Lifetime and luminous efficiency are also correspondingly improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The NMR spectrum of organometallic iridium complex L-13 provided in Example 1 of this invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] This invention provides an organometallic iridium complex selected from compounds with the following structural formulas:

[0024] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 and R 14 Each group 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 groups; for example, each group 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 any one of the groups shown in the following structural formulas:

[0025] In this context, * represents the position that is replaced.

[0026] In Formula 1, R on the benzene ring of dibenzofuran 10 The number of elements is either 1 or 2. If R 10 The number of R is 2, at this time there are 2 R 10 They can be the same, or they can be different.

[0027] S1 is selected from substituted or unsubstituted dibenzofurans, and S1 is fused to any position on the benzene ring of an adjacent dibenzofuran. Wherein, if S1 is selected from substituted dibenzofurans, 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 groups shown in the following structural formulas: The asterisk (*) represents the substitution position. There can be one, two, or three substituents.

[0028] It should be noted that the C1-C10 alkyl groups described in the embodiments of the present invention can be 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, or can be substituted C1-C10 alkyl groups in which at least one hydrogen atom on at least one carbon is substituted by a halogen, cyano, hydroxyl, or alkoxy group. Examples of embodiments of the present invention are as follows: for example, one, two, or three hydrogen atoms on one carbon are substituted, or one hydrogen atom on each of two carbons is substituted, one carbon has two hydrogen atoms substituted, or one hydrogen atom on one carbon is substituted.

[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, or substituted C3-C8 cycloalkyl groups in which one or more hydrogen atoms are substituted.

[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, or aryl groups in which one or more hydrogens are substituted.

[0031] Similarly, the substituted or unsubstituted 4-8 member heterocyclic groups provided in the embodiments of the present invention include heterocyclic groups such as furan, tetrahydrofuran, pyridine, piperidine, and thiophene ethylthiazole.

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

[0033]

[0034]

[0035]

[0036]

[0037] Furthermore, the organometallic iridium complex is selected from any one of the compounds shown in 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, which improves photoelectric performance. The presence of furan ring enhances molecular rigidity and thermal stability. The addition of dibenzofuran to the benzofuran ring suppresses the quenching effect caused by intermolecular aggregation, thereby improving the luminous efficiency, lifetime and driving voltage of organic electroluminescent devices.

[0060] Secondly, embodiments of the present invention provide a method for preparing an organometallic iridium complex, comprising: synthesizing according to the following synthetic route:

[0061]

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

[0063] Step 2: Under an inert gas atmosphere, 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., isopropanol), and a chloroalkane (e.g., dichloromethane) are added under nitrogen conditions. After reacting at 20-35°C for 40-55 hours, the mixture is passed through a silica gel funnel and washed with dichloromethane until no product is obtained. The combined organic phases are then evaporated to dryness to obtain intermediate L-A2.

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

[0065] Thirdly, embodiments of the present invention provide a luminescent material comprising the aforementioned organometallic iridium complex.

[0066] Fourthly, embodiments of the present invention provide an organic electroluminescent device, which includes a light-emitting layer formed from the aforementioned light-emitting material.

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

[0068] Example 1

[0069] This invention provides a method for preparing organometallic iridium complexes, comprising:

[0070]

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

[0072]

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

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

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

[0076]

[0077] Step 4: Weigh intermediate E-13 (158 mmol), F-13 (CAS No.: 883499-24-9158 mmol), potassium carbonate (237 mmol), and NN dimethylformamide (560 mL) under nitrogen conditions, and 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: Weigh intermediate G-13 (80.1 mmol), NN dimethylformamide (340 mL), palladium acetate (1.6 mmol), and tricycloethylphosphide (1.7 mmol) under nitrogen conditions, react at 120 °C for 12 h; add water and ethanol, perform column chromatography, and recrystallize to obtain intermediate H-13 (19 g, yield 56%).

[0080] For steps four and five, refer to patent CN113121584A.

[0081]

[0082] Step 6: Under nitrogen atmosphere, weigh intermediate H-13 (55 mmol), I-13 (CAS No.: 852362-24-482.9 mmol), tetraphenylphosphine palladium (1.1 mmol), toluene (190 mL), ethanol (190 mL), water (95 mL), and potassium carbonate (166 mmol). React at 90 °C for 24 h, separate the contents, evaporate to dryness, and precipitate by column chromatography to obtain intermediate J-13 (14.9 g, yield 70%). HPLC purity: >99.0%.

[0083]

[0084] Step 7: Weigh the following raw materials under nitrogen atmosphere: 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, wash, and dry to obtain intermediate J-13-2 (14.1 g, yield 82%).

[0085] Step 8: Weigh the following raw materials under nitrogen atmosphere: J-13-2 (11.2 mmol), silver trifluoromethanesulfonate (24.6 mmol), dichloromethane (240 mL), and isopropanol (60 mL). React at 25 °C for 48 h. Pass the mixture through a silica gel funnel and evaporate to dryness to obtain intermediate J-13-3 (12.9 g, yield 81%).

[0086]

[0087] Step 9: Under nitrogen atmosphere, weigh 14.5 mmol of raw material J-13-3, 36 mmol of J-13, and 220 mL of ethanol. React at 90 °C for 48 h. Filter and column chromatography to obtain the final product L-13 (8.36 g, 65% yield). HPLC purity: >99.3%. Mass spectrometry: 886.23. Specifically, the NMR spectrum of product L-13 can be found in [reference needed]. Figure 1 .

[0088] Device Example 1

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

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

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

[0092] Device Examples 2-12: Organic electroluminescent devices as provided in Device Examples 2-12 were prepared according to the preparation method provided in Device Example 1, with the only difference being that L-13 was replaced with L-18, L-23, L-35, L-46, L-56, L-76, L-83, L-164, L-175, L-228, L-298, and L-338.

[0093] Comparative Examples 1-6: Organic electroluminescent devices as provided in Comparative 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 shown in the following structural formula:

[0094]

[0095] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in Examples 1-13 and Comparative Examples 1-6 were characterized at a brightness of 15000 nits. The test results are shown in Table 1 below. (Test results are normalized to Comparative Example 1):

[0096] Table 1 Test Results

[0097]

[0098]

[0099] As shown in Table 1, a comparison with Comparative Examples 1 and 2 reveals that the compounds provided in the embodiments of the present invention, by adding a furan ring, form an extended π-electron system through conjugation, thus improving photoelectric performance. The presence of the furan ring also enhances molecular rigidity and thermal stability. Furthermore, a comparison with Comparative Example 3 shows that adding dibenzofuran to the benzofuran ring suppresses the quenching effect caused by intermolecular aggregation and improves the thermal stability of the material. Therefore, the organic electroluminescent devices prepared using the compounds provided in the embodiments of the present invention as luminescent layer doping materials exhibit significantly lower driving voltage and significantly improved luminous efficiency and lifetime compared to the organic electroluminescent devices prepared in the comparative examples. A comparison of Examples 9, 10, and 12 with Comparative Examples 5, 6, and 4 shows that while adding dibenzofuran does not significantly increase luminous efficiency and device lifetime compared to adding benzofuran, the increased dipole moment enhances the tendency for charge separation within molecules or at interfaces, reducing exciton binding energy and thus promoting charge dissociation and transport efficiency, thereby lowering the driving voltage.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An organometallic iridium complex, characterized in that, It is selected from compounds with the following structural formulas: Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 and R 14 Each group is independently selected from hydrogen, deuterium, tritium, fluorine, cyano, -CH3, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, phenyl, -CD3, and any one of the groups shown in the following structural formulas: , where * represents the position to be replaced; In Formula 1, R on the benzene ring of dibenzofuran 10 The number of them is 1 or 2; S1 is selected from substituted or unsubstituted dibenzofurans, and S1 is fused to any position on the benzene ring of an adjacent dibenzofuran; the substituents of the dibenzofuran of S1 are selected from at least one of halogen, cyano, unsubstituted C1-C10 alkyl and unsubstituted C3-C8 cycloalkyl.

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

3. The organometallic iridium complex according to claim 1 or 2, characterized in that, The substituents of S1 dibenzofuran are selected from at least one of fluorine, cyano, methyl, tert-butyl, and groups shown in the following structural formulas: , where * represents the position to be replaced.

4. An organometallic iridium complex, characterized in that, The organometallic iridium complex is selected from any one of the compounds shown in the following structural formulas: 。 5. A method for preparing the organometallic iridium complex according to claim 1, characterized in that, include: Perform the synthesis according to the following synthesis path: 。 6. The preparation method according to claim 5, characterized in that, include: Under an inert gas atmosphere, the raw material LA and iridium trichloride trihydrate are mixed and reacted at 100-120℃ for 40-55 hours to form intermediate L-A1; In an inert gas atmosphere, intermediate L-A1 and silver trifluoromethanesulfonate are mixed and reacted at 20-35°C for 40-55 hours to form intermediate L-A2; Under an inert gas atmosphere, the intermediates L-A2 and LB are mixed and reacted at 80-100°C for 40-55 hours.

7. A luminescent material, characterized in that, It includes the organometallic iridium complex as described in any one of claims 1-4.

8. An organic electroluminescent device, characterized in that, It includes a light-emitting layer formed from the light-emitting material as described in claim 7.

Images