An organic metal iridium complex, a light-emitting material and an organic electroluminescent device

Abstract

This invention discloses an organometallic iridium complex, a luminescent material, and an organic electroluminescent device, relating to the field of organic electroluminescence technology. The structural formula of the organometallic iridium complex is shown in Formula I: ; wherein, R9, R... 10 R 11 and R 12 At least one of them is adamantane; R 13 R 14 and R 15 At least one of them is fluorine or cyano. This invention introduces electron-withdrawing groups, such as cyano or fluorine, onto the dibenzofuran ring host, thereby altering the molecular configuration of the compound, increasing the conjugated system, and regulating the electrochemical properties of the compound. This results in an organic compound that, when used in organic electroluminescent devices, lowers the device's startup voltage and improves its luminous efficiency and lifetime. Simultaneously, this invention adds adamantane at the pyridine position. The hydrophobicity of adamantane reduces the absorption of moisture by the OLED material, decreasing the corrosion of the device by water and oxygen, thus improving the material's lifetime.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescence technology, and more specifically, to an organometallic iridium complex, a luminescent material, and an organic electroluminescent device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are a class of devices with a sandwich-like structure, consisting of positive and negative electrode layers and an organic functional material layer sandwiched between them. When a voltage is applied to the electrodes of an OLED device, positive charges are injected from the positive electrode and negative charges from the negative electrode. Under the influence of an electric field, the positive and negative charges migrate and recombine within the organic layer, emitting light. Due to their advantages such as high brightness, fast response, wide viewing angle, simple manufacturing process, and flexibility, OLEDs have attracted significant attention in the fields of new display technology and new lighting technology. Currently, this technology is widely used in display panels for new lighting fixtures, smartphones, and tablets, and its application is further expanding to large-size display products such as televisions. It is a rapidly developing and technologically demanding new display technology. Therefore, research on high-efficiency phosphorescent organic light-emitting diodes provides a significant impetus for the development of the flat panel and portable display industries. Thus, developing a high-performance phosphorescent material that enables organic light-emitting diodes to possess comprehensive characteristics such as high efficiency, long lifespan, and low voltage is a technical problem that urgently needs to be solved by researchers in this field.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide an organometallic iridium complex, a luminescent material, and an organic electroluminescent device.

[0005] This invention is implemented as follows: In a first aspect, the present invention provides an organometallic iridium complex, the structural formula of which is shown in Formula I: ; Among them, R1, R2, R3, R4, R5, R6, R7, R8, R 16 Each is independently selected from hydrogen, deuterium, -F, -CN, methyl, ethyl, -CD3, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, trimethylsilyl, trimethylgermanium, substituted or unsubstituted C2-C. 10 Alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C 20 Any one of aryl, substituted or unsubstituted 4-8 membered heterocyclic groups; R9, R 10 R 11 and R12 At least one of them is adamantane, which is represented by Ad in the following structures; R 13 R 14 and R 15 At least one is fluorine or cyanine; X is selected from any one of O, S, Se, Si, Ge, C, and N; Y is selected from CR A Or N, CR A For R A Replacement C, R A Selected from: -H, -D, -F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and any one of the following substituents: ; * indicates a replacement position.

[0006] In a second aspect, the present invention provides a luminescent material comprising an organometallic iridium complex as described in any of the above embodiments.

[0007] Thirdly, the present invention provides an organic electroluminescent device comprising a light-emitting layer made of a light-emitting material as described in the above embodiments.

[0008] The present invention has the following beneficial effects: The organometallic iridium complexes provided by this invention introduce electron-withdrawing groups, such as cyano and fluorine, onto the dibenzofuran ring host, thereby altering the molecular configuration, increasing the conjugation system, and regulating the electrochemical properties of the compounds. This results in organic compounds used in organic electroluminescent devices that lower the device's startup voltage and improve its luminous efficiency and lifetime. Simultaneously, by adding adamantane at the pyridine position, the hydrophobicity (low surface energy) of adamantane reduces the absorption of moisture by the OLED material, decreasing the corrosion of the device by water and oxygen, thus improving the material's lifetime. Attached Figure Description

[0009] 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.

[0010] Figure 1 The image shows the hydrogen nuclear magnetic resonance spectrum of the organometallic iridium complex L-5 prepared in Example 1 of this invention. Detailed Implementation

[0011] 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.

[0012] This invention provides an organometallic iridium complex, the structural formula of which is shown in Formula I: ; Among them, R1, R2, R3, R4, R5, R6, R7, R8, R 16 Each is independently selected from hydrogen, deuterium, -F, -CN, methyl, ethyl, -CD3, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, trimethylsilyl, trimethylgermanium, substituted or unsubstituted C2-C. 10 Alkyl, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C 20 Any one of aryl, substituted or unsubstituted 4-8 membered heterocyclic groups; R9, R 10 R 11 and R 12 At least one of them is adamantane, which is represented by Ad in the following structures; R 13 R 14 and R 15 At least one is fluorine or cyanine; X is selected from any one of O, S, Se, Si, Ge, C, and N; Y is selected from CR A Or N, CR A For R A Replacement C, R A Selected from: -H, -D, -F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and any one of the following substituents: ; * indicates a replacement position.

[0013] The organometallic iridium complexes provided by this invention introduce electron-withdrawing groups, such as cyano and fluorine, onto the dibenzofuran ring host, thereby altering the molecular configuration, increasing the conjugation system, and regulating the electrochemical properties of the compounds. This results in organic compounds used in organic electroluminescent devices that lower the device's startup voltage and improve its luminous efficiency and lifetime. Furthermore, by adding adamantane at the pyridine position, the hydrophobicity (low surface energy) of adamantane reduces the absorption of moisture by the OLED material, thus mitigating the corrosion of the device by water and oxygen and improving the material's lifetime.

[0014] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R 16 Independently selected from: -H, -D, -F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and the following substituents:

[0015] * indicates a replacement position.

[0016] In some typical but non-limiting embodiments, the term "substituted or unsubstituted" means substituted with or without a substituent, wherein the substituents include, but are not limited to, -D, -F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and any one of the following substituents:

[0017] * indicates a replacement position.

[0018] This invention defines R9 and R 10 R 11 and R 12 At least one of them is adamantane, while R9 and R 10 R 11 and R 12 The substituents not being adamantane are independently selected from -H, -D, -F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and any one of the following substituents: ; * indicates a replacement position.

[0019] In this invention, adamantane is added to the pyridine position. Due to the hydrophobicity (low surface energy) of adamantane, the absorption of water by OLED materials can be reduced, thus reducing the corrosion of devices by water and oxygen and improving the lifespan of the materials.

[0020] R 13R 14 and R 15 At least one is fluorine or cyanine, while R 13 R 14 and R 15 The non-fluorine or cyano substituents are independently selected from -H, -D, F, -CN, -CH3, -CD3, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, phenyl, and any one of the following substituents:

[0021] * indicates a replacement position.

[0022] In this invention, by adding a cyano group (-CN) or a fluorine atom (-F) to dibenzofuran, the charge transport efficiency is improved by changing the molecular orbital energy level. When applied to electroluminescent devices, the driving voltage is significantly reduced.

[0023] Furthermore, ligand L A Select any one of the following structural formulas from LA-1 to LA-254: .

[0024] Formula I has any one of the structures of compounds 1-432: .

[0025] The above are just some specific structural forms, but this series of organometallic iridium complexes are not limited to the above molecular structures. Other specific molecular structures can be obtained by simply changing some simple groups and their substituted groups and substitution positions, which will not be elaborated here.

[0026] A second objective of this invention is to provide a method for preparing the aforementioned organometallic iridium complex. The organometallic iridium complex of this invention can be prepared by synthetic methods known to those skilled in the art. Alternatively, the following reaction process is preferred for preparation, and the specific synthetic route is as follows:

[0027] The specific steps are as follows: Step 1: Under an inert gas atmosphere, mix the raw material LA and iridium trichloride trihydrate, and react at 100-120℃ for 40-55 hours to form intermediate L-A1.

[0028] Specifically, under nitrogen conditions, raw material LA, iridium trichloride trihydrate, alcohol ether solvent (e.g., ethylene glycol ethyl ether) and water are added, reacted at 100℃-120℃ for 40-55h, filtered, washed with ethanol and petroleum ether, and dried to obtain intermediate L-A1.

[0029] 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.

[0030] 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 organic phases are then combined and dried by rotary evaporation to obtain intermediate L-A2.

[0031] Step 3: Under an inert gas atmosphere, mix intermediates L-A2 and LB and react at 80-100℃ for 40-55 hours.

[0032] Specifically, intermediates L-A2 and LB, along with an alcohol solvent (e.g., ethanol), are added under nitrogen atmosphere and reacted at 80-100°C for 40-55 hours. The mixture is then filtered, and the product L is purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:1-1:3). The substituents described above are the same as those previously mentioned.

[0033] In addition, the present invention also provides a luminescent material comprising the above-mentioned organometallic iridium complex.

[0034] The present invention also provides an organic electroluminescent device comprising a light-emitting layer prepared from the above-mentioned light-emitting material. The light-emitting layer comprises a host material and a dopant material, wherein the dopant material comprises the light-emitting material, and the weight ratio of the host material to the dopant material is 85-95:5-15.

[0035] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0036] Example 1: Preparation of organometallic iridium complex L-5 G-5 corresponds to LA in the general formula of the synthesis route, which is not existing technology and needs to be synthesized first: The specific operation and process route are as follows:

[0037] Step 1: Weigh raw material A-5 (CAS No.: 29021-90-7 1eq), chloroform 15eq and acetic acid 5eq under nitrogen conditions, and stir for 5 minutes; add NBS (1eq) at 25℃ and stir for 2 hours; add saturated brine (6eq), and purify intermediate B-5 by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:2), yield: 35.2%.

[0038]

[0039] Step 2: Under nitrogen atmosphere, weigh B-5 (1 eq), pinacol diborate (1.5 eq), 1,4-dioxane (20 eq), and potassium acetate (2.5 eq), and add them sequentially to the reaction system. Replace the nitrogen atmosphere twice. Under nitrogen atmosphere, add tris(dibenzylacetone)dipalladium (0.02 eq) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.08 eq). React at 80°C for 24 h. After the reaction is stopped, cool the system to room temperature, pass the system through a silica gel funnel, evaporate to dryness, and purify by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:4) to obtain intermediate C-5, yield: 50.6%.

[0040]

[0041] Step 3: Under nitrogen atmosphere, weigh D-5 (1 eq CAS: 458532-96-2), E-5 (1.1 eq CAS: 7314-85-4), potassium carbonate (3 eq), toluene (20 eq), ethanol (10 eq), and water (10 eq). Replace the nitrogen atmosphere twice, then add tetraphenylphosphine palladium (0.08 eq) under nitrogen atmosphere. React at 70°C for 24 h. After the reaction is complete, cool to room temperature, separate the ethyl acetate, evaporate to dryness, and purify the intermediate F-5 by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:3), yield: 60.8%.

[0042]

[0043] Step 4: Under nitrogen atmosphere, weigh F-5 (1 eq), C-5 (1.1 eq), potassium carbonate (3 eq), toluene (20 eq), ethanol (10 eq), and water (10 eq). Replace the nitrogen atmosphere twice. Add tetraphenylphosphine palladium (0.02 eq) under nitrogen atmosphere and react at 80°C for 24 h. After the reaction is complete, cool to room temperature, separate the ethyl acetate, evaporate to dryness, and purify the intermediate G-5 by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:2), yield: 63.0%.

[0044]

[0045] Step 5: Weigh raw material J-5-1 (CAS No.: 1008-89-52.5eq), iridium trichloride (1eq), ethylene glycol ethyl ether (12eq) and water (4eq) under nitrogen conditions, react at 120℃ for 48h, filter, wash and dry to obtain intermediate J-5-2, with a yield of 72.1%.

[0046] Step 6: Weigh the raw materials J-5-2 (1 eq), silver trifluoromethanesulfonate (2 eq), dichloromethane (21 eq) and isopropanol (7 eq) under nitrogen conditions, react at 25°C for 48 h, pass through a silica gel funnel, and evaporate to dryness to obtain intermediate J-5-3 with a yield of 80.4%.

[0047]

[0048] Step 7: Weigh the raw materials J-5-3 (1 eq), G-5 (2.5 eq), and ethanol (20 eq) under nitrogen atmosphere, react at 90°C for 48 h, filter, and purify the final product L-5 by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:1). Yield: 63.1%.

[0049] HPLC purity: >99.3%.

[0050] Mass spectrometry: Test value 904.37.

[0051] Elemental analysis: C: 66.41%, H: 4.35%, N: 6.20%, O: 1.77%.

[0052] The hydrogen NMR spectrum of L-5 is as follows: Figure 1 As shown.

[0053] Device Example 1 Device Example 1 provides an organic electroluminescent device. The light-emitting layer of this organic electroluminescent device is prepared using product L-5 from Example 1. Specifically, the preparation method of this organic electroluminescent device is as follows: The ITO glass substrate with a coating thickness of 1500 Å 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 an evaporation machine.

[0054] First, a 100 Å thick layer of 4,4',4''-tris[2-naphthylphenylamino]triphenylamine (i.e., 2-TNATA) is deposited on the ITO (anode) as a hole injection layer. Then, a 900 Å thick layer of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (i.e., NPB) is deposited on the hole injection layer as a hole transport layer. Following this, a 400 Å thick layer of the host material 4,4'' is deposited. An organic electroluminescent device is obtained by depositing '-di(N-carbazolyl)1,1'-biphenyl (i.e., CBP) and a dopant material (compound formula L-5 provided in Example 1) in a weight ratio of 90:10 as the light-emitting layer. Then, an ALq3 layer with a thickness of 400 Å is deposited on the light-emitting layer as the electron transport layer. Next, an electron injection layer material Liq with a thickness of 150 Å is deposited on the electron transport layer. Finally, a cathode material Al with a thickness of 1000 Å is deposited on the electron injection layer.

[0055] The structural formulas of the materials 2-TNATA, NPB, CBP, ALq3, and Liq used above are as follows:

[0056] Device Comparison Examples 1-8: The organic electroluminescent device was fabricated using the same method as in device example L-5. The structure of the green doped compound in the emitting layer is as follows:

[0057] Device Examples 2-36: Other device embodiments were prepared according to the preparation method provided in Device Embodiment 1, the only difference being that L-5 was replaced with a corresponding material.

[0058] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in the above-described device embodiments and comparative examples were characterized at a brightness of 15000 nits. The test results are shown in Table 1 below. (The test results are normalized using device comparative example 1): Table 1. Statistical Table of Test Results for Different Devices

[0059] According to Table 1, a comparison with comparative examples shows that by adding electron-withdrawing groups to the structure, fluorine and cyano groups lower the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels of the material through inductive effects, enhancing electron injection capability, reducing electron transport barriers, and lowering driving voltage. Simultaneously, electron-withdrawing groups can reduce exciton quenching and improve the material's luminescence efficiency. Electron-withdrawing groups enhance intermolecular forces, forming a rigid "hydrogen-bonded cage" structure that suppresses non-radiative decay paths, thereby improving the material's lifespan. Furthermore, the large-volume cage structure of adamantane can suppress close packing (such as π-π packing) between OLED material molecules through steric hindrance effects, preventing material crystallization or aggregation and thus improving charge mobility.

[0060] Comparing Device Example 1, Device Comparative Example 1, and Device Comparative Example 7, it can be seen that Device Example 1 introduces both adamantane and cyano groups, Device Comparative Example 1 introduces only adamantane, and Device Comparative Example 7 introduces only cyano groups. The driving voltage of Device Example 1 is significantly lower than that of Device Comparative Examples 1 and 7, and its luminous efficiency and lifespan are significantly better than those of Device Comparative Examples 1 and 7. This fully demonstrates that the simultaneous introduction of adamantane and cyano groups can synergistically improve the performance of the device.

[0061] In summary, the organometallic iridium complexes provided by this invention, by introducing electron-withdrawing groups such as cyano and fluorine onto the dibenzofuran ring host, alter the molecular configuration of the compound, increase the conjugated system, and regulate the electrochemical properties of the compound. This results in the organic compound being used in organic electroluminescent devices, reducing the device's startup voltage and improving its luminous efficiency and lifetime. Furthermore, by adding adamantane at the pyridine position, the hydrophobicity (low surface energy) of adamantane reduces the absorption of moisture by the OLED material, thus mitigating the corrosion of the device by water and oxygen and improving the material's lifetime.

[0062] 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, Its structural formula is shown in Formula I: ； Among them, R1, R2, R3, R4, R5, R6, R7, R8, R 16 Each is independently selected from hydrogen or methyl; R9, R 10 R 11 and R 12 At least one of them is adamantane, which is represented by Ad in the following structures; R9, R 10 R 11 and R 12 The substituents that are not adamantane are independently selected from -H; R 13 R 14 and R 15 At least one is a fluorine or cyanine group; R 13 R 14 and R 15 The substituents that are not fluorine or cyano groups are independently selected from -H; X is selected from O, S, or -C(CH3)2; Y is selected from CR A Or N, R A Choose from: -H, -F, or -CN.

2. The organometallic iridium complex according to claim 1, characterized in that, Equation I has any of the following structures: 。 3. A luminescent material, characterized in that, It includes organometallic iridium complexes as described in any one of claims 1-2.

4. An organic electroluminescent device, characterized in that, It includes a light-emitting layer made of the light-emitting material as described in claim 3.

5. The organic electroluminescent device according to claim 4, characterized in that, The light-emitting layer comprises a host material and a dopant material, wherein the dopant material comprises the light-emitting material, and the weight ratio of the host material to the dopant material is 85-95:5-15.

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