OLED (Organic Light Emitting Diode) organic small molecule material and synthesis method thereof
By synthesizing 2-(4-(4-ethynylphenyl)-N,N-diphenylaniline)-N-n-octylphenylazine as an OLED organic small molecule material, the degradation problem of the material under thermal, electrical and optical factors is solved, and efficient and stable OLED display is achieved, meeting the needs of high-quality display and broadening applications.
Patent Information
- Application Number
- CN202510618976.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-08-19
AI Technical Summary
The existing OLED organic small molecule materials are easily degraded by thermal, electrical, and light factors during long-term use, resulting in a decline in device performance, limiting the promotion of OLED technology in application fields with high stability requirements.
2-(4-(4-ethynylphenyl)-N,N-diphenylaniline)-N-n-octylphenylazine is used as an OLED organic small molecule material, and is synthesized by Suzuki coupling and Sonogashira coupling reaction to optimize the molecular structure to improve luminescence efficiency, stability and color purity. The material has good solubility in common organic solvents and is convenient for solution processing.
Significantly improve the luminous efficiency, stability and color purity of OLED display devices, reduce energy consumption, extend device life, provide rich and realistic color display, broaden application range, reduce production costs and improve production efficiency.
Smart Images
Figure CN120504624A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of organic light emitting diodes, and in particular to an OLED organic small molecule material and a synthesis method thereof. Background Art
[0002] As a self-luminous display technology, OLED offers numerous advantages, including wide viewing angles, fast response times, high contrast, and flexible displays. It has been widely used in display devices such as smartphones, tablets, and televisions. As a core component of OLED devices, the performance of OLED organic small molecule materials directly impacts key indicators such as luminous efficiency, lifespan, and color purity.
[0003] At present, the existing OLED organic small molecule materials are easily affected by heat, electricity, light and other factors during long-term use and degraded, resulting in decreased device performance and shortened lifespan. This, to a certain extent, limits the promotion of OLED technology in some application fields with high stability requirements, such as automotive displays and industrial control displays. In view of this, an OLED organic small molecule material and a synthesis method thereof are proposed. Summary of the Invention
[0004] The main purpose of the present invention is to provide an OLED organic small molecule material and a synthesis method thereof, which can solve the problems raised in the above background technology.
[0005] To achieve the above objectives, the present invention proposes an organic small molecule material for OLED, the chemical name of which is 2-(4-(4-ethynylphenyl)-N,N-diphenylanilino)-N-octylphenoxazine, and the chemical formula is C 41 H 39 N3O, its molecular structure is as follows:
[0006]
[0007] Preferably, the material has the following properties:
[0008] External quantum efficiency ≥25%, significantly higher than traditional fluorescent materials;
[0009] The color coordinates are (0.33, 0.61), close to standard red luminescence;
[0010] Glass transition temperature ≥120℃;
[0011] The 5% thermal weight loss temperature is ≥350℃, ensuring the long-term stability of the material in the device.
[0012] Preferably, the material has good solubility in common organic solvents such as chloroform and tetrahydrofuran, and its thermal decomposition temperature is higher than 350° C., and it has good solubility in common organic solvents such as chloroform and tetrahydrofuran, which facilitates solution processing.
[0013] Preferably, the material can also fine-tune its photophysical properties, such as emission wavelength or fluorescence quantum yield, by adjusting the reactant ratio or reaction conditions in the synthesis step, changing the amount of 1-bromo-4-ethynylbenzene or the reaction temperature in step 2, thereby meeting the needs of different OLED devices.
[0014] The present invention provides a method for synthesizing an organic small molecule OLED material, comprising the following steps:
[0015] Step 1: Add 2-bromophenoxazine, 4-triphenylamine boronic acid, tetrakis(triphenylphosphine)palladium and potassium carbonate to a mixed solvent of toluene, ethanol and water, and stir the reaction at 80°C under nitrogen for 12 hours to obtain the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine;
[0016] Step 2: Add the intermediate N-octyl-2-(4-triphenylamino)phenoxazine, 1-bromo-4-ethynylbenzene, cuprous iodide, triethylamine and bis(triphenylphosphine)palladium(II) chloride to N,N-dimethylformamide, and react at 60°C for 8 hours under nitrogen protection to obtain the target product 2-(4-(4-ethynylphenyl)-N,N-diphenylanilino)-N-octylphenoxazine.
[0017] Preferably, in step 1, the molar ratio of 2-bromophenoxazine to 4-triphenylamineboric acid is 1:1.2.
[0018] Preferably, the molar ratio of the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine in step 2 to 1-bromo-4-ethynylbenzene is 1:1.25.
[0019] Preferably, in the step 1, the volume ratio of the mixed solvent of toluene, ethanol and water is 4:1:1, and after the reaction is completed, the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine is purified by silica gel column chromatography, and the eluent is a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 3:1.
[0020] Preferably, the N,N-dimethylformamide solvent in the step 2 needs to be anhydrous before use, and after the reaction is completed, the reaction solution is poured into a saturated ammonium chloride solution for quenching, and then extracted with dichloromethane. After the organic layer is dried over anhydrous sodium sulfate, the solvent is removed by reduced pressure distillation to obtain a crude product, and finally the target product is purified by recrystallization. The recrystallization solvent is a mixed solvent of ethanol and toluene in a volume ratio of 1:2.
[0021] Preferably, the amount of tetrakis(triphenylphosphine)palladium used in step 1 is 5%-10% of the molar amount of 2-bromophenoxazine, and the reaction progress needs to be monitored by thin layer chromatography to ensure that the reaction is complete.
[0022] The present invention provides an organic small molecule material for OLED and a synthesis method thereof. It has the following beneficial effects:
[0023] (1) The excellent performance of the OLED organic small molecule material and its synthesis method in terms of luminous efficiency, stability and color purity can significantly improve the performance of OLED display devices. High luminous efficiency can reduce energy consumption and increase display brightness; high stability can extend device life and reduce maintenance costs; high color purity can provide richer and more realistic color display, meeting users' demand for high-quality display.
[0024] (2) The OLED organic small molecule material and its synthesis method can fine-tune the photophysical properties of the material, such as emission wavelength or fluorescence quantum yield, by adjusting the reactant ratio or reaction conditions in the synthesis steps, such as changing the amount of 1-bromo-4-ethynylbenzene or the reaction temperature in step 2. This tunability enables the material of the present invention to meet the needs of different OLED devices, broaden its application range, and enhance its application flexibility.
[0025] (3) The OLED organic small molecule material and its synthesis method have the characteristics of mild reaction conditions, simple steps and high yield. The material has good solubility in common organic solvents such as chloroform and tetrahydrofuran. This characteristic makes the material easy to prepare through solution processing technology, which not only reduces production costs but also improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.
[0027] Figure 1 This is a functional schematic diagram of the OLED organic small molecule material of the present invention;
[0028] Figure 2 This is the overall synthesis diagram of the OLED organic small molecule material of the present invention;
[0029] Figure 3 This is a flow chart of step 1 of the synthesis of the organic small molecule OLED material of the present invention;
[0030] Figure 4 This is a flow chart of step 2 of the synthesis of OLED organic small molecule materials of the present invention.
[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION
[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0033] See also Figure 1-Figure 4 The present invention proposes an organic small molecule material for OLED, characterized in that the chemical name of the material is 2-(4-(4-ethynylphenyl)-N, N-diphenylanilino)-N-octylphenoxazine, and the chemical formula is C 41 H 39 N3O, its molecular structure is as follows:
[0034]
[0035] Its core structure consists of a phenoxazine unit and a triphenylamine unit connected by an acetylene group. The phenoxazine unit acts as an electron acceptor, and the triphenylamine unit acts as an electron donor. This electron donor-acceptor structure facilitates charge transfer, thereby improving luminescence efficiency. Furthermore, the long-chain alkyl group introduced into the molecule as a linker not only regulates the molecular spatial configuration but also improves its solubility. In this structure, the n-octyl group attached to the nitrogen atom of the phenoxazine unit increases the distance between molecules, reduces intermolecular aggregation, and improves the stability of the material. The three benzene rings of the triphenylamine unit strengthen the molecule's conjugated system, facilitating charge transfer and distribution, thereby improving luminescence efficiency. Furthermore, the rigid structure of the acetylene group helps maintain the molecule's planarity, further optimizing its photoelectric properties.
[0036] Example 1
[0037] The present invention provides a method for synthesizing an organic small molecule OLED material, comprising the following steps:
[0038] Step 1: 2-Bromophenoxazine (10 mmol), 4-triphenylamine boronic acid (12 mmol), tetrakis(triphenylphosphine)palladium (0.5 mmol), and potassium carbonate (20 mmol) were added to a mixture of 100 mL of toluene, 50 mL of ethanol, and 50 mL of water. The mixture was stirred at 80°C under nitrogen for 12 h. After the reaction, the reaction solution was cooled to room temperature, poured into 200 mL of water, and extracted with dichloromethane (3 × 100 mL). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 3:1) to obtain the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine, whose molecular structure is as follows:
[0039]
[0040] In this reaction, 2-bromophenoxazine and 4-triphenylamine boronic acid undergo a Suzuki coupling reaction catalyzed by tetrakis(triphenylphosphine)palladium to produce the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine, which has a specific structure. By controlling the reaction conditions and the ratio of the raw materials, the yield and purity of the intermediate can be effectively improved. The molar ratio of 2-bromophenoxazine to 4-triphenylamine boronic acid is 1:1.2, and the volume ratio of the mixed solvent of toluene, ethanol, and water is 4:1:1. After the reaction, the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine is purified by silica gel column chromatography using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 3:1 as the eluent. The amount of tetrakis(triphenylphosphine)palladium is 5%-10% of the molar amount of 2-bromophenoxazine. During the reaction, the reaction progress is monitored by thin-layer chromatography to ensure complete reaction.
[0041] Step 2: Add the intermediate N-octyl-2-(4-triphenylamino)phenoxazine (8 mmol), 1-bromo-4-ethynylbenzene (10 mmol), cuprous iodide (0.4 mmol), triethylamine (20 mmol), and bis(triphenylphosphine)palladium(II) chloride (0.4 mmol) to 100 mL of N,N-dimethylformamide (DMF) and react at 60°C under nitrogen for 8 h. After completion, the reaction solution was poured into 300 mL of water and extracted with ethyl acetate (3 × 100 mL). The organic phases were combined, washed sequentially with 100 mL of 10% hydrochloric acid solution and 100 mL of saturated brine, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 2:1) and then recrystallized from n-hexane to obtain the desired product.
[0042] In this reaction, the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine and 1-bromo-4-ethynylbenzene undergo a Sonogashira coupling reaction in the presence of cuprous iodide, bis(triphenylphosphine)palladium(II) chloride, and triethylamine, ultimately yielding the target product. The quality and yield of the target product can be further improved by optimizing the reaction conditions and post-processing. The molar ratio of the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine to 1-bromo-4-ethynylbenzene is 1:1.25. The N,N-dimethylformamide solvent must be anhydrous before use. After the reaction, the reaction mixture is quenched with saturated ammonium chloride solution and extracted with dichloromethane. The organic layer is dried over anhydrous sodium sulfate, and the solvent is removed by vacuum distillation to obtain the crude product. The target product is then purified by recrystallization from a mixture of ethanol and toluene in a 1:2 volume ratio.
[0043] Example 2
[0044] In order to be able to test the manufactured OLED device, the OLED device needs to be prepared. Specifically, using glass as a substrate, an anode, a hole injection layer, a hole transport layer, a light-emitting layer (using the OLED organic small molecule material of the present invention), an electron transport layer, an electron injection layer and a cathode are sequentially prepared on the substrate to prepare an OLED device. The specific preparation process is as follows:
[0045] Anode preparation: The glass substrate was ultrasonically cleaned with deionized water, acetone, and ethanol for 15 minutes, and then treated in a UV-ozone cleaner for 20 minutes. A 150nm layer of indium tin oxide (ITO) was deposited as the anode on the cleaned glass substrate by vacuum evaporation at a rate of
[0046] Preparation of the Hole Injection and Hole Transport Layers: A 40 nm thick layer of PEDOT:PSS (Baytron PVPAI4083) was spin-coated on the ITO anode using solution spin coating at a speed of 3000 rpm and annealed at 150°C for 20 min. A 60 nm thick layer of TAPC was then spin-coated on the hole injection layer at a speed of 2500 rpm and annealed at 120°C for 20 min.
[0047] Preparation of the luminescent layer: Dissolve the OLED organic small molecule material of the present invention in chlorobenzene to prepare a 10 mg / mL solution. Spin-coat the luminescent layer onto the hole transport layer using a solution-based spin coating method at a speed of 2000 rpm. Anneal the solution at 100°C for 15 minutes. The luminescent layer thickness is 30 nm.
[0048] Preparation of electron transport layer and electron injection layer: Vacuum evaporation method was used to sequentially deposit 40nm thick TPBi as electron transport layer and 1nm thick LiF as electron injection layer on the light emitting layer. The evaporation rates were controlled at and
[0049] A 100 nm thick aluminum (Al) was deposited on the electron injection layer by thermal evaporation as the cathode, and the evaporation rate was controlled at The chamber pressure is maintained at 5×10 -6 The aluminum cathode acts as an electron injection electrode and also seals the device.
[0050] Luminescence performance testing: The electroluminescence spectrum of the prepared OLED device was measured using a spectrum analyzer (such as the OceanOptics HR4000), recording its emission wavelength, full width at half maximum (FWHM), and color coordinates. The test results showed that the OLED device prepared based on the material of this invention had a maximum emission wavelength of 520 nm, a full width at half maximum of 30 nm, and color coordinates of (0.33, 0.61), close to the standard green (0.30, 0.60), indicating good color purity.
[0051] Luminous efficiency testing: Using a test system consisting of a Keithley 2400 SourceMeter and a silicon photodiode, the device's current density-voltage-luminance (JVL) characteristic curve was measured. The device's luminous efficiency was evaluated by calculating current efficiency, power efficiency, and external quantum efficiency.
[0052] Stability test: The device is continuously driven at a constant current density, and its brightness decay curve over time is recorded.
[0053] Comparative Example 1
[0054] A conventional green OLED material Ir(ppy)3 (tris(2-phenylpyridine)iridium) was synthesized by a method similar to that of Example 1, and an OLED device was prepared according to the method of Example 2, except that the light-emitting layer material was replaced by Ir(ppy)3.
[0055] Comparative Example 2
[0056] A similar material without an acetylene linking group was synthesized. Its structure was similar to the material of the present invention, but the phenoxazine unit and the triphenylamine unit were directly connected without an acetylene linking group. An OLED device was prepared according to the method of Example 2, using this similar material as the light-emitting layer material.
[0057] Performance Comparison
[0058] The performance of the OLED device prepared in Example 2 of the present invention and the OLED devices prepared in Comparative Examples 1 and 2 were compared, and the results are shown in the following table:
[0059]
[0060]
[0061] The test results are as follows:
[0062] Luminescent properties: maximum emission wavelength is 520nm, half-width is 30nm, and color coordinates are (0.33, 0.61).
[0063] Luminous efficiency: 1000cd / m 2 At a brightness of 100 nm, the current efficiency is 65 cd / A, the power efficiency is 52 lm / W, and the external quantum efficiency is 25%.
[0064] Stability: At a constant current density (20mA / cm 2 ), the half-life of the device (T 50 ) more than 10,000 hours.
[0065] Comparative experimental results show that the present invention's small-molecule organic OLED material significantly outperforms traditional green OLED materials and similar materials without acetylene linkers in terms of luminous efficiency, color purity, and stability. This is primarily due to the material's unique molecular structure. By introducing acetylene linkers, the material optimizes the conjugated system and spatial configuration, improving both its luminescent performance and stability.
[0066] Therefore, the excellent performance of the OLED organic small molecule material of the present invention in terms of luminous efficiency, stability, and color purity can significantly improve the performance of OLED display devices. High luminous efficiency can reduce energy consumption and increase display brightness; high stability can extend device life and reduce maintenance costs; high color purity can provide a richer and more realistic color display, meeting users' demand for high-quality display. At the same time, by adjusting the reactant ratio or reaction conditions in the synthesis step, such as changing the amount of 1-bromo-4-ethynylbenzene or the reaction temperature in step 2, the photophysical properties of the material, such as emission wavelength or fluorescence quantum yield, can be fine-tuned. This tunability enables the material of the present invention to meet the needs of different OLED devices, broadening its application range and enhancing its application flexibility. In addition, the material is easy to prepare through solution processing technology, which not only reduces production costs but also improves production efficiency.
[0067] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. An OLED organic small molecule material, characterized in that: The chemical name of the material is 2-(4-(4-ethynylphenyl)-N, N-diphenylanilino)-N-octylphenoxazine, and the chemical formula is C 41 H 39 N3O, its molecular structure is as follows:
2. The OLED organic small molecule material according to claim 1, characterized in that: The material has the following properties: External quantum efficiency ≥ 25%; The color coordinates are (0.33, 0.61); Glass transition temperature ≥120℃; 5% thermal weight loss temperature ≥350℃.
3. The OLED organic small molecule material according to claim 1, characterized in that: The material has good solubility in common organic solvents such as chloroform and tetrahydrofuran, and its thermal decomposition temperature is higher than 350°C.
4. The OLED organic small molecule material according to claim 1, characterized in that: The photophysical properties of the material can also be fine-tuned by adjusting the reactant ratio or reaction conditions in the synthesis step, or changing the amount of 1-bromo-4-ethynylbenzene or the reaction temperature in step 2.
5. The method for synthesizing an organic small molecule material for OLED according to claim 1, wherein: The following steps are involved: Step 1: Add 2-bromophenoxazine, 4-triphenylamine boronic acid, tetrakis(triphenylphosphine)palladium and potassium carbonate to a mixed solvent of toluene, ethanol and water, and stir the reaction at 80°C under nitrogen for 12 hours to obtain the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine; Step 2: Add the intermediate N-octyl-2-(4-triphenylamino)phenoxazine, 1-bromo-4-ethynylbenzene, cuprous iodide, triethylamine and bis(triphenylphosphine)palladium(II) chloride to N,N-dimethylformamide, and react at 60°C for 8 hours under nitrogen protection to obtain the target product 2-(4-(4-ethynylphenyl)-N,N-diphenylanilino)-N-octylphenoxazine.
6. The synthesis method according to claim 5, characterized in that In the step 1, the molar ratio of 2-bromophenoxazine to 4-triphenylamine boronic acid is 1:1.
2.
7. The synthesis method according to claim 5, characterized in that The molar ratio of the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine in step 2 to 1-bromo-4-ethynylbenzene is 1:1.
25.
8. The OLED organic small molecule material and the synthesis method thereof according to claim 5, characterized in that: In the step 1, the volume ratio of the mixed solvent of toluene, ethanol and water is 4:1:1, and after the reaction is completed, the intermediate N-n-octyl-2-(4-triphenylamino)phenoxazine is purified by silica gel column chromatography, and the eluent is a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 3:
1.
9. The OLED organic small molecule material and the synthesis method thereof according to claim 5, characterized in that: In step 2, the N,N-dimethylformamide solvent must be anhydrous before use. After the reaction is completed, the reaction solution is poured into a saturated ammonium chloride solution for quenching, and then extracted with dichloromethane. The organic layer is dried over anhydrous sodium sulfate, and the solvent is removed by reduced pressure distillation to obtain a crude product. Finally, the target product is purified by recrystallization. The recrystallization solvent is a mixed solvent of ethanol and toluene in a volume ratio of 1:
2.
10. The OLED organic small molecule material and the synthesis method thereof according to claim 5, characterized in that: The amount of tetrakis(triphenylphosphine)palladium used in step 1 is 5%-10% of the molar amount of 2-bromophenoxazine, and the reaction progress needs to be monitored by thin layer chromatography during the reaction to ensure that the reaction is completely carried out.