Hyperbranched high-refractive-index light extraction material as well as preparation method and application thereof
By preparing hyperbranched high-refractive-index light extraction materials, the problem of low photon escape efficiency in OLED and LED devices was solved, achieving high transparency and high refractive index light extraction effects, thereby improving the luminous efficiency and stability of the devices.
Patent Information
- Application Number
- CN202510988392.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-28
AI Technical Summary
The low photon escape efficiency in existing OLED and LED devices leads to energy waste and shortened device lifespan. Existing light extraction materials suffer from high-temperature brittleness, complex preparation processes, and high costs.
By employing hyperbranched high-refractive-index light extraction materials and introducing structures such as sulfur atoms and aromatic rings, high-transparency and high-refractive-index light extraction materials are prepared using free radical polymerization methods, which are suitable for flexible display devices.
It significantly improves the luminous efficiency of OLED and LED devices, enhances the environmental stability and process compatibility of materials, and is suitable for fields such as organic light-emitting diodes and dual charge-coupled devices.
Smart Images
Figure CN120842574A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically relating to a hyperbranched high refractive index light extraction material, its preparation method, and its application. Background Technology
[0002] OLEDs and LEDs, as mainstream display and lighting devices, boast advantages such as high color gamut, low energy consumption, and thinness and flexibility, and are widely used in consumer electronics, automotive displays, and solid-state lighting. However, their actual luminous efficiency still faces significant technical bottlenecks due to the low photon escape efficiency within the devices. Specifically, the large refractive index difference between the organic light-emitting layer or GaN semiconductor layer and air and conventional packaging materials causes most photons generated by the light-emitting layer to undergo total internal reflection at the interface, failing to escape effectively. Studies show that only 20%–30% of photons can be effectively extracted in traditional OLED devices, while approximately 20%–30% of photons in LED devices are confined within the device. This not only wastes energy but also affects device lifespan due to the conversion of light energy into heat.
[0003] To address the aforementioned issues, existing technologies primarily improve photon escape efficiency by introducing light extraction structures or materials into the device. Common techniques include: 1) using a high-refractive-index dielectric layer as an optical transition layer to reduce refractive index mismatch; 2) constructing micro / nano structures (such as microlens arrays, scattering particles, etc.) on or inside the device surface to alter the photon propagation path through light scattering effects; and 3) using organic-inorganic hybrid materials to balance high refractive index with flexibility. However, these existing technologies still have significant shortcomings: inorganic high-refractive-index materials (such as chalcogenide glasses, metal oxides, etc.) typically require high-temperature processing and are brittle, making them unsuitable for flexible display devices; while organic-inorganic hybrid materials possess good processing performance, their roughness is insufficient for application requirements, and their long-term stability is poor; and complex micro / nano structures face challenges such as complex fabrication processes and high costs, hindering large-scale production and application.
[0004] Therefore, developing a novel light extraction material that combines high transparency (visible light transmittance >90%), high refractive index (n>1.7), excellent environmental stability, and good process compatibility is of great significance for breaking through the efficiency bottleneck of existing OLED, LED and other devices and promoting the development of display and lighting technologies. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a high-transparency, high-refractive-index hyperbranched high-refractive-index light extraction material, its preparation method and application. By means of free radical polymerization, sulfur atoms, aromatic rings and other structures are appropriately introduced into the polymer backbone, and the molecular gaps are reduced by hyperbranching, so that the material has excellent transparency in the visible light region and excellent refractive index.
[0006] To address the aforementioned technical problems, this invention discloses a hyperbranched high-refractive-index light extraction material, the general structural formula of which is as follows:
[0007] Ar1 is a unit with an aromatic ring, Ar2 is a unit with an aromatic ring, sulfur, or hydrogen atom, Ar3 is a unit with an aromatic ring or sulfur, and the wavy line represents repeating units.
[0008] Specifically, Ar1 is selected from any of the following structures:
[0009] * indicates a connection point.
[0010] Specifically, the Ar2 is selected from any of the following structures:
[0011] * indicates a connection point.
[0012] Specifically, the Ar3 is selected from any of the following structures:
[0013] * indicates a connection point.
[0014] In some embodiments of the present invention, the hyperbranched high refractive index light extraction material has any one of the following structures:
[0015]
[0016]
[0017]
[0018]
[0019]
[0020] .
[0021] Furthermore, the preparation method of the above-mentioned hyperbranched high refractive index light extraction material is also within the scope of protection of this invention. The preparation method includes the following steps: monomers with alkynyl building units and monomers with dithiol building units are subjected to thiol-alkynyl click polymerization and / or photopolymerization under the conditions of organic solvent, additives and initiator to obtain the hyperbranched high refractive index light extraction material.
[0022] Specifically, the general reaction formula for the process is as follows:
[0023] Specifically, the mercapto-acetylene click polymerization reaction includes the following steps: at room temperature, a monomer with a dithiol group is added to an organic solvent and stirred for 5 minutes until completely dissolved to obtain solution one; after dissolving the monomer with an acetyl group in the organic solvent, solution one is added, and stirring is continued for 3-5 minutes until homogeneous to obtain mixed solution two; the initiator used in the mercapto-acetylene click polymerization reaction is added to mixed solution two, and the mixture is stirred at 90 °C for 2 hours; after the reaction is completed, post-processing is performed to obtain the final product, which is a highly transparent, high-refractive-index hyperbranched, high-refractive-index light extraction material.
[0024] Specifically, the photopolymerization reaction includes the following steps: dissolving an alkynyl monomer, a dithiol monomer, and a photoinitiator in an organic solvent, stirring for 5-30 minutes, then spin-coating the solution onto a quartz sheet, followed by pre-baking on a hot stage to obtain a prepolymer film, curing the film under ultraviolet light for 20-60 minutes, developing it in an organic solvent, and then post-baking and hard-film treatment to obtain a transparent film, which is a highly transparent, high-refractive-index hyperbranched, high-refractive-index light extraction material.
[0025] Specifically, the organic solvent includes one or more of propylene glycol methyl ether, toluene, hexane, cyclohexane, dioxane, tetrahydrofuran, diethyl ether, acetonitrile, dichloromethane, acetone, chloroform, propylene glycol methyl ether acetate, dimethyl sulfoxide, N,N-dimethylformamide, and 1,2-dichlorobenzene.
[0026] Specifically, the initiator of the mercapto-alkyne click polymerization reaction includes one or more of dimethyl azobisisobutyrate, azobisisoheptanenitrile, and azobisisobutyronitrile.
[0027] Specifically, the photopolymerization reaction uses one or more of the following initiators: benzophenone, 4-methylbenzophenone, isopropylthioxanthone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinphenyl)butanone, and N,N-dimethylaminobenzoate isooctyl ester.
[0028] Furthermore, the application of the aforementioned hyperbranched high-refractive-index light extraction material in the fabrication of any one of organic light-emitting diodes, microlens elements in charge-coupled devices, high-performance complementary image sensors, all-polymer optoelectronic devices, polymer-based optical waveguide devices, polymer-based photovoltaic devices, and polymer-based memory devices is also within the scope of protection of this invention.
[0029] Specifically, in some embodiments of the present invention, the average refractive index and transparency of the hyperbranched high-refractive-index light extraction material were characterized, demonstrating that the hyperbranched high-refractive-index light extraction material provided by the present invention possesses good refractive index and transparency. Furthermore, using the hyperbranched high-refractive-index light extraction material prepared in the embodiments of the present invention as a light extraction layer applied to organic light-emitting diodes (OLEDs), a comparison of luminous efficiency with that of basic OLEDs shows that the hyperbranched high-refractive-index light extraction material can significantly improve the luminous efficiency of OLEDs, demonstrating the promising application prospects of the aforementioned hyperbranched high-refractive-index light extraction material in the fabrication of OLEDs, microlens elements in charge-coupled devices (CCDs), high-performance complementary image sensors, all-polymer optoelectronic devices, polymer-based optical waveguide devices, polymer-based photovoltaic devices, and polymer-based memory devices.
[0030] Beneficial effects 1. This invention uses monomers with alkynyl groups and monomers with dithiol groups to obtain hyperbranched polymers through free radical polymerization, which effectively incorporates a high molar polarizability structure into the polymer, enabling the material to simultaneously possess excellent properties of high refractive index and high transparency.
[0031] 2. This type of highly transparent, high-refractive-index hyperbranched high-refractive-index light extraction material can be applied in fields such as organic light-emitting diodes, microlens elements in dual charge-coupled devices, high-performance complementary image sensors, all-polymer optoelectronic devices, polymer-based optical waveguides, photovoltaics, and memory devices. Attached Figure Description
[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.
[0033] Figure 1 This is a refractive index diagram of polymer P1 obtained in Example 1 of the present invention.
[0034] Figure 2 This is a refractive index diagram of polymer P2 obtained in Example 2 of the present invention.
[0035] Figure 3 This is a refractive index diagram of polymer P3 obtained in Example 3 of the present invention.
[0036] Figure 4 This is a refractive index diagram of polymer P4 obtained in Example 4 of the present invention.
[0037] Figure 5 This is a transmittance diagram of polymer P1 obtained in Example 1 of the present invention.
[0038] Figure 6 This is a transmittance diagram of polymer P2 obtained in Example 2 of the present invention.
[0039] Figure 7 This is a transmittance diagram of polymer P3 obtained in Example 3 of the present invention. Detailed Implementation
[0040] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.
[0041] This invention provides a hyperbranched high-refractive-index light extraction material, the general structural formula of which is as follows:
[0042] The wavy line is a repeating unit.
[0043] Ar1 is selected from the following structures: ; Ar2 is selected from the following structure: ; Ar3 is selected from the following structure:
[0044] In Ar1, Ar2, and Ar3, * indicates the connection position.
[0045] This invention also provides a method for preparing a hyperbranched high-refractive-index light extraction material, specifically comprising the following steps: using a monomer with an alkynyl group and a monomer with a dithiol group, under the conditions of an organic solvent, additives, and an initiator, via thiol-alkynyl click polymerization or photopolymerization, to obtain the highly transparent, high-refractive-index hyperbranched high-refractive-index light extraction material. The general reaction formula for the process is shown below:
[0046] Example 1: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light extraction P1 is as follows:
[0047] M1 (0.2 mmol, 2 equiv.), Ar3 (0.3 mmol, 3 equiv.), and isopropylthioxanthone (0.008 mmol, 0.08 equiv.) were dissolved in propylene glycol methyl ether (12 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz sheet to obtain a prepolymer film. The film was then cured under ultraviolet light for 60 minutes to obtain a transparent film P1. Figure 1 The refractive index diagram of polymer P1 is shown below. Figure 5 This is a transmittance diagram for polymer P1. (From...) Figure 1 and Figure 5 As can be seen, the average refractive index of polymer P1 in the visible light region is 1.78, and the transparency is 95%.
[0048] Example 2: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracted P2 is as follows:
[0049] At room temperature, M2 (2 mmol, 2 equiv.) was added to the reaction vessel, and the nitrogen atmosphere was purged 3-4 times. Chloroform (5 mL) was added, and the mixture was stirred at room temperature for 5 minutes until completely dissolved. Ar3 (3 mmol, 3 equiv.) and the initiator azobisisobutyronitrile (1.5 mmol, 1.53 equiv.) were dissolved in chloroform (5 mL) and injected into the vessel. The mixture was stirred at room temperature for 2 hours. After the reaction was complete, the residue was completely removed by precipitation twice with methanol (250 mL). The final product, white powder P2, was obtained by filtration and drying, with a yield of 93%. A transparent film was prepared by dissolving 7 mg of the final product white powder P2 in 1 mL of tetrahydrofuran and spin-coating it onto a quartz plate at 1000 rpm. The refractive index and transparency were measured by ellipsometry and UV-Vis spectrophotometer. Figure 2 The refractive index diagram of polymer P2 is shown below. Figure 6 This is a transmittance diagram of polymer P2, from... Figure 2 and Figure 6 As can be seen, the average refractive index of polymer P2 is 1.82, and the transparency is 99%.
[0050] Example 3: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracted P3 is as follows:
[0051] At room temperature, M3 (2 mmol, 2 equiv.) was added to the reaction vessel, and the argon gas was purged 3-4 times. Tetrahydrofuran (5 mL) was added and stirred at room temperature for 5 minutes until completely dissolved. Ar3 (3 mmol, 3 equiv.) and the initiator azobisisobutyronitrile (1.5 mmol, 1.53 equiv.) were dissolved in tetrahydrofuran (5 mL) and injected into the vessel. The reaction was stirred at room temperature for 2 hours. After the reaction was completed, the residue was completely removed by precipitation twice with methanol (250 mL). The final product, white powder P3, was obtained by filtration and drying, with a yield of 96%. A transparent film was prepared by dissolving 7 mg of the final product white powder P3 in 1 mL of tetrahydrofuran and spin-coating it onto a quartz plate at 1000 rpm. The refractive index and transparency were measured by ellipsometry and UV-Vis spectrophotometer. Figure 3 The refractive index diagram of polymer P3 is shown. Figure 7 This is a transmittance diagram for polymer P3. (From...) Figure 3 and Figure 7 As can be seen, the average refractive index of polymer P3 is 1.74, and the transparency is 98%.
[0052] Example 4: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracting P4 is as follows:
[0053] M4 (0.2 mmol, 2 equiv.), Ar3 (0.3 mmol, 3 equiv.), and benzophenone (0.008 mmol, 0.08 equiv.) were dissolved in propylene glycol methyl ether acetate (11 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz plate to obtain a prepolymer film. The film was then cured under ultraviolet light for 60 minutes to obtain a transparent film P4. Figure 4 The image shows the refractive index of polymer P4 obtained in Example 4 of this invention. The average refractive index of polymer P4 in the visible light region is 1.74, and the transparency is 98%.
[0054] Example 5: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracted P5 is as follows:
[0055] M5 (0.2 mmol, 2 equiv.), Ar3 (0.3 mmol, 3 equiv.), and 1-hydroxycyclohexylphenyl ketone (0.008 mmol, 0.08 equiv.) were dissolved in 1,2-dichlorobenzene (12 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz sheet to obtain a prepolymer film. The film was then cured under ultraviolet light for 60 minutes to obtain a transparent film P5. Polymer P5 was tested and found to have an average refractive index of 1.71 and a transparency of 91% in the visible light region.
[0056] Example 6: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracted P6 is as follows:
[0057] M6 (0.2 mmol, 2 equiv.), Ar3 (0.3 mmol, 3 equiv.), and isooctyl N,N-dimethylaminobenzoate (0.008 mmol, 0.08 equiv.) were dissolved in dichloromethane (15 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz sheet to obtain a prepolymer film. The film was cured under ultraviolet light for 60 minutes to obtain a transparent film P6. The polymer P6 was tested and found to have an average refractive index of 1.83 and a transparency of 93% in the visible light region.
[0058] Example 7: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracting P7 is as follows:
[0059] M7 (0.2 mmol, 2 equiv.), Ar2 (0.3 mmol, 3 equiv.), and 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (0.008 mmol, 0.08 equiv.) were dissolved in 1,2-dichlorobenzene (4 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz sheet to obtain a prepolymer film. The film was then cured under ultraviolet light for 60 minutes to obtain a transparent film P7. The polymer P7 was tested and found to have an average refractive index of 1.69 and a transparency of 92% in the visible light region.
[0060] Example 8: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracting P8 is as follows:
[0061] M8 (0.2 mmol, 2 equiv.), Ar2 (0.3 mmol, 3 equiv.), and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (0.008 mmol, 0.08 equiv.) were dissolved in chloroform (10 mL). After stirring for 5 minutes, the solution was spin-coated onto a quartz plate to obtain a prepolymer film. The film was cured under ultraviolet light for 60 minutes to obtain a transparent film P8. The polymer P8 was tested and found to have an average refractive index of 1.84 and a transparency of 90% in the visible light region.
[0062] Example 9: Select Ar1 as Ar2 is Ar3 is The preparation process of highly transparent, high-refractive-index hyperbranched light-extracting P9 is as follows:
[0063] M9 (0.2 mmol, 2 equiv.), Ar2 (0.3 mmol, 3 equiv.), and benzophenone (0.008 mmol, 0.08 equiv.) were dissolved in toluene (8 mL). After stirring for 5 minutes, the solution was spin-coated onto a silicon wafer to obtain a prepolymer film. The film was then cured under ultraviolet light for 60 minutes to obtain a transparent film P9. Polymer P9 was tested and found to have an average refractive index of 1.65 and a transparency of 95% in the visible light region.
[0064] Comparative Example 1: The hyperbranched high-refractive-index light extraction materials P1-P9 prepared in Examples 1-9 were used as light extraction layers to construct organic light-emitting diodes (OLEDs), and their luminous efficiency was compared with that of basic OLED structures. Table 1 shows the material structure and light extraction effect of Examples 1-9 as light extraction layers applied to OLEDs.
[0065] Table 1. Material structure and light extraction effect of Examples 1-9 as light extraction layers applied to organic light-emitting diodes.
[0066] Specifically, Glass serves as the supporting substrate; Ag, as ultrathin silver, is the transparent anode, while P1~P9, as the light extraction layers, are ultrathin semi-transparent / semi-reflective layers that optimize optics / electricity in the organic light-emitting diode; HAT-CN is the high-performance hole injection layer; NPB is the main hole transport layer; TCTA is the auxiliary hole transport / exciton blocking layer; CBP: 5 wt% Ir(ppy)3 is the green phosphorescent layer; TmPyPB is the electron transport / exciton blocking layer; Liq is the electron injection / cathode buffer layer; Al is the thick reflective metal; P1~P9, as key new material layers, are inserted between the glass substrate and the dual HAT-CN / Ag anode, aiming to improve device efficiency by enhancing light extraction and / or optimizing the electrode structure.
[0067] As shown in Table 1, by using P1 to P9 as light extraction layers in organic light-emitting diodes, the luminous efficiency of OLED devices can be significantly improved, with the luminous effect being significantly improved by 8% to 17%, among which P8 has the best effect as a light extraction layer.
[0068] This invention provides a hyperbranched high-refractive-index light extraction material, its preparation method, and its application. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.
Claims
1. A hyperbranched high-refractive-index light extraction material, characterized in that, The general structural formula of the hyperbranched high-refractive-index light extraction material is as follows: ； Ar1 is a unit with an aromatic ring, Ar2 is a unit with an aromatic ring, sulfur, or hydrogen atoms, and Ar3 is a unit with an aromatic ring or sulfur.
2. The hyperbranched high-refractive-index light extraction material according to claim 1, characterized in that, The Ar1 is selected from any of the following structures: ； * indicates a connection point.
3. The hyperbranched high-refractive-index light extraction material according to claim 1, characterized in that, The Ar2 is selected from any of the following structures: ； * indicates a connection point.
4. The hyperbranched high-refractive-index light extraction material according to claim 1, characterized in that, The Ar3 is selected from any of the following structures: ； * indicates a connection point.
5. The hyperbranched high-refractive-index light extraction material according to claim 1, characterized in that, The hyperbranched high-refractive-index light extraction material has any one of the following structures: ； ； ； ； ； ； 。 6. The method for preparing the hyperbranched high refractive index light extraction material according to any one of claims 1 to 5, characterized in that, The process includes the following steps: monomers of building units with alkynyl structures and monomers of building units with dithiol groups are subjected to thiol-alkynyl click polymerization and / or photopolymerization under the conditions of organic solvents, additives and initiators to obtain the hyperbranched high refractive index light extraction material.
7. The preparation method according to claim 6, characterized in that, The organic solvent includes one or more of propylene glycol methyl ether, toluene, hexane, cyclohexane, dioxane, tetrahydrofuran, diethyl ether, acetonitrile, dichloromethane, acetone, chloroform, propylene glycol methyl ether acetate, dimethyl sulfoxide, N,N-dimethylformamide, and 1,2-dichlorobenzene.
8. The preparation method according to claim 6, characterized in that, The thiol-alkyne click polymerization reaction uses one or more of the following as initiators: dimethyl azobisisobutyrate, azobisisoheptanenitrile, and azobisisobutyronitrile.
9. The preparation method according to claim 6, characterized in that, The photopolymerization reaction uses one or more of the following initiators: benzophenone, 4-methylbenzophenone, isopropylthioxanthone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholin-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinphenyl)butanone, and N,N-dimethylaminobenzoate isooctyl ester.
10. The use of the hyperbranched high refractive index light extraction material according to any one of claims 1 to 5 in the preparation of any one of organic light-emitting diodes, microlens elements in charge-coupled devices, high-performance complementary image sensors, all-polymer optoelectronic devices, polymer-based optical waveguide devices, polymer-based photovoltaic devices, and polymer-based memory devices.