Stretchable imidazole polyethylene electron transport material, preparation method and application thereof
Through chemical crosslinking, combining electron transport materials with stretchable elastomers, an imidazole polyethylene electron transport material with high tensile properties and high stability was prepared, which solved the shortcomings in tensile properties and stability of existing stretchable electronic devices and achieved efficient electroluminescent devices.
Patent Information
- Application Number
- CN202510370121.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2025-07-04
AI Technical Summary
Existing stretchable electronic devices have shortcomings in terms of the tensile properties and electronic functional stability of materials, especially the electronic structure and chemical properties of electronic transmission materials in blue-photoelectric phosphorescent devices are not fully met, which limits the improvement of device performance.
Through chemical crosslinking, the electron transport material structural unit is combined with the stretchable elastomer unit to prepare a stretchable imidazole polyethylene electron transport material. Radical polymerization is carried out under organic solvents and initiator conditions, and electron transport layer with high tensileability and high stability is formed.
The high tensile properties and photoelectric properties of the elastomer are balanced, and electroluminescent devices with high tensile properties, high efficiency and high stability are prepared for flexible display and wearable electronic devices.
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Figure CN120248234A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of organic photoelectric materials, and specifically relates to a stretchable imidazole polyethylene electron transport material, a preparation method and an application thereof. Background Art
[0002] As a promising emerging frontier technology, stretchable electronics has attracted the attention of many researchers in related fields with its outstanding advantages such as high stretchability, high efficiency, compatibility and self-healing, and has strongly promoted its wide application in many fields such as biomedicine, wearable devices, military defense, soft robots, etc. Among them, stretchable optoelectronic devices, as the key carrier of stretchable electronics, have become a hot research focus.
[0003] Stretchable optoelectronic devices generally cover electrode layers, optoelectronic functional layers, and interface layers. The coordinated development of the stretchability of each functional layer is crucial. At present, stretchable electronic devices are mainly prepared in two ways: first, they are improved at the process level, such as designing the device into special forms such as folded paper structures, wrinkled structures, pre-stretched coating structures, etc., to give it stretchable properties, or change the force mode of the device; second, the material is modified to have stretchable properties, such as designing and manufacturing stretchable organic conductive polymers, stretchable composite materials and other materials with special properties. Although stretchable electronic technology has made significant progress, it still faces a series of technical challenges. For example, how to further improve the stretchability of materials and how to ensure the stability of electronic functions are issues that need to be solved urgently.
[0004] In addition, the shortage of high-performance organic electron transport materials has, to a certain extent, limited the improvement and development of the performance of organic electroluminescent devices. For blue-light electrophosphorescent devices, their electron transport materials need to have specific electronic structures and chemical properties so that they can efficiently transport electrons under the action of an electric field. Such materials usually have a large electron affinity and a high electron mobility, which is conducive to the injection and transport of electrons. At the same time, they must also have good chemical stability and thermal stability to ensure long-term and stable operation in the device. These stringent requirements have brought considerable obstacles to the design and development of high excited state energy electron transport materials. Summary of the invention
[0005] The purpose of the present invention is to design a stretchable imidazole polyethylene electron transport material, a preparation method and its application, and to combine the electron transport material structural unit with the stretchable elastomer unit by chemical crosslinking to achieve the stretchability and photoelectric properties of the elastomer.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:
[0007] A stretchable imidazole polyethylene electron transport material has the following general structural formula:
[0008]
[0009] Among them, R is the structural unit of the electron transport material, x, y, and z respectively represent the molar ratios of the corresponding components, and x + y + z = 1.
[0010] Furthermore, y = 0.5 - 0.9, and the electron transport material structural unit R is selected from the following structures:
[0011]
[0012] Where * is the connection position.
[0013] Furthermore, the stretchable imidazole polyethylene electron transport material is selected from the following structures:
[0014]
[0015] A method for preparing a stretchable imidazole polyethylene electron transport material, characterized in that the method steps are as follows:
[0016] Using polyethylene glycol methacrylate, ethyl 2-(butylamino)carbonyloxyacrylate, and the electron transport material structural unit as raw materials, under the conditions of an organic solvent and an initiator, through free radical polymerization, the described stretchable imidazole polyethylene electron transport material is obtained.
[0017] Furthermore, the polymerization reaction should be carried out under inert gas conditions, and the initiator is azobisisobutyronitrile.
[0018] An application of a stretchable imidazole polyethylene electron transport material in the field of stretchable electroluminescent devices.
[0019] An intrinsic electroluminescent device includes a stretchable substrate, a stretchable electrode, a stretchable electron / hole transport layer, and a stretchable electron / hole injection layer. It is characterized in that the stretchable electron transport layer is the stretchable imidazole polyethylene electron transport material described in claim 1.
[0020] Through the above technical solutions, the following beneficial effects can be obtained:
[0021] In the present invention, through chemical cross-linking, the electron transport structural unit is combined with the stretchable elastomer unit, realizing the stretchability and optoelectronic properties of the elastomer. This stretchable imidazole polyethylene electron transport material can be used as an electron transport layer material to prepare highly stretchable, efficient, and highly stable electroluminescent devices, and can be applied to fields such as flexible displays, sensing detection, and wearable electronic devices. Description of the Drawings
[0022] Figure 1 It is the thermogravimetric analysis diagram of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention;
[0023] Figure 2 It is the PL spectrum diagram of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention;
[0024] Figure 3 It is the infrared spectrum diagram of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention;
[0025] Figure 4 It is the device structure diagram of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention;
[0026] Figure 5 It is the EL spectrum diagram of the device of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention;
[0027] Figure 6 It is the current density-voltage-luminance curve diagram of the device of the stretchable imidazole polyethylene electron transport material AEM-3 of the present invention. Detailed implementation manners
[0028] The following further describes the present invention in conjunction with the attached Figures 1-6 illustrated as follows:
[0029] Example 1
[0030] When R is selected as the preparation of the stretchable imidazole polyethylene electron transport material AEM-1:
[0031]
[0032] Under the protection of N2, Pd(PPh3)4 (0.29 g, 0.12 mmol) was rapidly added to a mixed system of 2-(4-bromophenyl)-1-phenyl-1H-benzo[d]imidazole (1.5 g, 2 mmol), 4,4,5,5-tetramethyl-2-(4-vinylphenyl)-1,3,2-dioxaborolane (1.03 g, 2.1 mmol), K2CO3 aqueous solution (2 M, 20 ml), ethanol (60 ml) and toluene (120 ml), and the mixture was heated to 80 °C and reacted for 12 h. After the reaction, the reaction system was cooled to room temperature, the solvent was removed by reduced pressure distillation, dichloromethane and distilled water were added, the organic layer was separated, anhydrous magnesium sulfate (MgSO4) was added for drying and filtration, the organic solvent was removed by reduced pressure distillation, and the obtained crude product was separated and purified by column chromatography. A white solid was obtained using a mixed solvent of petroleum ether and dichloromethane (V:V = 1:2) as the eluent, and the yield was 89% (0.71 g).
[0033] R1 (0.5 g, 1 mmol), polyethylene glycol methacrylate (2.32 g, 12 mmol), ethyl 2-(butylamino)carbonyloxyacrylate (2.31 g, 8 mmol), and azobisisobutyronitrile were added to a reaction vessel. The nitrogen was evacuated and replaced 3 - 4 times, then tetrahydrofuran (10 mL) was added to dissolve the mixture, and the reaction was carried out under reflux stirring at 65 °C for 24 hours. After the reaction, it was cooled to room temperature, the excess solvent was removed by distillation under reduced pressure, and the product was precipitated and purified by adding it to a large amount of methanol. After vacuum filtration, it was dried under vacuum at room temperature to obtain 0.67 g of the stretchable imidazole polyethylene electron transport material AEM-1, with a yield of 71%.
[0034] Example 2
[0035] When R was selected as the preparation of the stretchable imidazole polyethylene electron transport material AEM-2:
[0036]
[0037] Under the protection of N2, Pd(PPh3)4 (0.22 g, 0.12 mmol) was rapidly added to a mixed system of 9-(4-bromophenyl)carbazole (1 g, 2 mmol), 4,4,5,5-tetramethyl-2-(4-vinylphenyl)-1,3,2-dioxaborolane (0.75 g, 2.1 mmol), aqueous K2CO3 solution (2 M, 20 ml), ethanol (60 ml), and toluene (120 ml). The reaction was heated to 80 °C for 12 h. After the reaction, the reaction system was cooled to room temperature, the solvent was removed by distillation under reduced pressure, dichloromethane and distilled water were added, the organic layer was separated, anhydrous magnesium sulfate (MgSO4) was added for drying and filtration, and the organic solvent was removed by distillation under reduced pressure. The obtained crude product was separated and purified by column chromatography, and a white solid was obtained using a mixed solvent of petroleum ether and dichloromethane (V:V = 1:2) as the eluent, with a yield of 71% (0.38 g).
[0038] R2 (0.5 g, 1 mmol), polyethylene glycol methacrylate (2.5 g, 12 mmol), ethyl 2-(butylamino)carbonyloxyacrylate (2.49 g, 8 mmol), and azobisisobutyronitrile were added to a reaction vessel. The nitrogen was evacuated and replaced 3 - 4 times, then tetrahydrofuran (10 mL) was added to dissolve the mixture, and the reaction was carried out under reflux stirring at 65 °C for 24 hours. After the reaction, it was cooled to room temperature, the excess solvent was removed by distillation under reduced pressure, and the product was precipitated and purified by adding it to a large amount of methanol. After vacuum filtration, it was dried under vacuum at room temperature to obtain 0.83 g of the stretchable imidazole polyethylene electron transport material AEM-2, with a yield of 78%.
[0039] Example 3
[0040] When R was selected as Preparation of the stretchable imidazole polyethylene electron transport material AEM-3:
[0041]
[0042] Under the protection of N2, Pd(PPh3)4 (0.13 g, 0.12 mmol) was rapidly added to a mixed system of 9-(3-bromo-5-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)-9H-carbazole (1 g, 2 mmol), 4,4,5,5-tetramethyl-2-(4-vinylphenyl)-1,3,2-dioxaborolane (0.47 g, 2.1 mmol), aqueous K2CO3 solution (2 M, 20 ml), ethanol (60 ml) and toluene (120 ml). The mixture was heated to 80 °C and reacted for 12 h. After the reaction, the reaction system was cooled to room temperature, and the solvent was removed by distillation under reduced pressure. Dichloromethane and distilled water were added, and the organic layer was separated. Anhydrous magnesium sulfate (MgSO4) was added for drying and filtration. The organic solvent was removed by distillation under reduced pressure. The obtained crude product was separated and purified by column chromatography. A white solid was obtained using a mixed solvent of petroleum ether and dichloromethane (V:V = 1:2) as the eluent, and the yield was 86% (0.45 g).
[0043] R3 (0.5 g, 1 mmol), polyethylene glycol methacrylate (1.61 g, 12 mmol), ethyl 2-(butylamino)carbonyl-2-oxopropenoate (1.60 g, 8 mmol) and azobisisobutyronitrile were added to a reaction vessel. Nitrogen was evacuated and replaced 3-4 times, and then tetrahydrofuran (10 mL) was added to dissolve the mixture. The reaction was carried out with reflux stirring at 65 °C for 24 h. After the reaction, the mixture was cooled to room temperature, and the excess solvent was distilled off under reduced pressure. The product was precipitated and purified by adding it to a large amount of methanol. After vacuum filtration, the stretchable imidazole polyethylene electron transport material AEM-3 (0.45 g) was obtained by vacuum drying at room temperature, and the yield was 52%.
[0044] Example 4: Preparation of an OLED device
[0045] The ITO glass was successively ultrasonically cleaned with isopropanol, acetone, detergent, deionized water, and isopropanol, dried in a vacuum drying oven at 75 °C, and treated with oxygen plasma. ITO / PEDOT:PSS was used as the anode, host2:IrG1 = 95:5 was used as the light-emitting layer, and CsF / Al was used as the cathode. The hole injection layer was PVK or PEDOT. Both the hole injection layer and the light-emitting layer were fabricated by spin coating. A thin film of the electron transport layer was prepared by spin coating one of AEM-1, AEM-2, and AEM-3 on the surface of the light-emitting layer. After introducing one of AEM-1, AEM-2, and AEM-3 as the electron transport layer, on the one hand, due to its high electron mobility, it is beneficial to the injection and transport of electrons, ensuring the balance of carriers inside the device; on the other hand, due to its high triplet energy level, it can effectively confine the phosphorescent triplet excitons in the light-emitting layer, improving the exciton utilization rate and the device performance.
[0046] This study focused on the stretchable imidazole polyethylene electron transport material AEM-3, and an in-depth exploration of its various properties was carried out. First, thermogravimetric analysis (TGA) was used to investigate the thermodynamic properties of the polymer AEM-3. It can be clearly seen from Figure 1 the TGA test curve that the thermal decomposition temperature (Td) of AEM-3 is 62.1 °C, showing good thermal stability. It is analyzed that this characteristic is closely related to its rigid molecular structure. The highly rigid benzene ring and imidazole ring structural units in the material limit the movement of the molecular chain, so that AEM-3 can still maintain stability in a high-temperature environment. Subsequently, photoluminescence (PL) spectroscopy was used to study its photophysical properties. It can be seen from Figure 2 that the maximum absorption wavelength (λ a ) of the polymer AEM-3 is in the range of 320.5 - 396.0 nm, and this absorption characteristic is closely related to the conjugation degree and structure of the molecule. In infrared spectroscopy ( Figure 3 ), the imidazole polyethylene material AEM-3 shows clear and unique characteristic absorption peaks. There is a broad peak attributed to the N-H stretching vibration at about 3400 - 3500 cm -1 , indicating the presence of active hydrogen connected to the nitrogen atom in the molecule; the strong absorption peak in the range of 1600 - 1650 cm -1 corresponds to the stretching vibration of C=N, which is a typical sign of the benzimidazole five-membered heterocyclic structure; the multiple absorption peaks at 1500 - 1600 cm -1 are the skeletal vibration peaks of the benzene ring, revealing the presence of the benzene ring in the benzimidazole molecule; the absorption peaks at 1300 - 1400 cm -1The absorption peak nearby can be attributed to the stretching vibration of C-N, further confirming the existence of the nitrogen-carbon bond in the molecule. These characteristic absorption peaks verify each other and jointly outline the infrared spectrum profile of the imidazole polyethylene material AEM-3, providing a key basis for its structural identification and analysis.
[0047] Based on the above research on the optical and thermal stability of polymer AEM-3, to further explore its application performance, the solution processing method was used to study its organic electroluminescence properties. Taking polymer AEM-3 as the electron transport layer, an OLEDs device with the structure of ITO / PEDOT:PSS(40nm) / host2:FIrpic=95:5(70nm) / AEM-3(15nm) / CsF(0.8nm) / Al(100nm) was fabricated (as Figure 4 shown), and the changes of current density with voltage and luminous brightness were studied. From Figure 5 the test results, it can be seen that for the device fabricated based on polymer AEM-3, the maximum emission peak of its EL spectrum is located at 389 nm, presenting blue light emission, indicating that the electron transition of the polymer AEM-3 material mainly occurs in the ultraviolet-blue light region, which is related to the conjugate length and electronic structure of the molecule. In addition, the turn-on voltage of this device is relatively low, only 5.3 V, and it has a relatively high luminous brightness, mainly due to the excellent electron injection and transport capabilities of the stretchable imidazole polyethylene electron transport material AEM-3 in the electron transport layer ( Figure 6 ).
[0048] All of the above are the preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, the modifications of various equivalent forms of the present invention all fall within the protection scope of the appended claims of this application.
Claims
1. A stretchable imidazole polyethylene electron transport material, characterized in that: The general structural formula thereof is as follows: Wherein, R is a structural unit of an electron transport material, x, y, and z respectively represent the molar ratios of the corresponding components, and x + y + z = 1.
2. The stretchable imidazole polyethylene electron transport material according to claim 1, characterized in that: y = 0.5 to 0.9, and the electron transport material structural unit R is selected from the following structures: Where * is the connection position.
3. The stretchable imidazole polyethylene electron transport material according to claim 1, characterized in that: The stretchable imidazole polyethylene electron transport material is selected from the following structures:
4. A method for preparing the stretchable imidazole polyethylene electron transport material according to claim 1, characterized in that: The method steps are as follows: Using polyethylene glycol methacrylate, ethyl 2-(butylamino)carbonyloxyacrylate, and the electron transport material structural unit as raw materials, under the conditions of an organic solvent and an initiator, through free radical polymerization, the stretchable imidazole polyethylene electron transport material is obtained.
5. A method for preparing a stretchable imidazole polyethylene electron transport material according to claim 4, characterized in that: The polymerization reaction should be carried out under an inert gas condition, and the initiator is azobisisobutyronitrile.
6. Application of a stretchable imidazole polyethylene electron transport material in the field of stretchable electroluminescent devices.
7. An intrinsic electroluminescent device, comprising a stretchable substrate, a stretchable electrode, a stretchable electron / hole transport layer, and a stretchable electron / hole injection layer, characterized in that, The stretchable electron transport layer is the stretchable imidazole polyethylene electron transport material described in claim 1.