A flexible transparent display film material

Abstract

The application provides a flexible transparent display film material and a preparation method thereof, and belongs to the technical field of display. The film material comprises a polymer matrix layer and light modulation microparticles dispersed in the polymer matrix layer; wherein the light modulation microparticles are nanomaterials with a core-shell structure, the core of which is an alloy inorganic material with continuously changing components along the radial direction, the shell of which is an inorganic semiconductor material layer, and the outer surface of the shell contains an organic ligand layer containing active functional groups. Through polymer molecular structure design, gradient ion distribution regulation and nanomaterial structure optimization, the dispersibility and stability of the nanomaterials in the matrix are significantly improved, the transparency, flexibility and light modulation performance of the film material are synergistically improved, and the film material has a wide application prospect in the field of flexible display.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic functional polymer materials technology, and in particular to a flexible and transparent display film material. Background Technology

[0002] With the rapid development of flexible display technology, the market has placed increasingly higher demands on the optical performance, mechanical properties, and structural stability of display materials.

[0003] Flexible transparent display films, as one of the core materials for next-generation display technologies, need to maintain excellent transparency while possessing good flexibility and controllable optical modulation capabilities. Nanomaterials, due to their unique size-dependent luminescence properties, high quantum yield, and excellent photostability, have become ideal optical modulation functional units in flexible display films. However, effectively integrating nanomaterials into flexible transparent films faces numerous technical challenges: on the one hand, nanomaterials are prone to aggregation in polymer matrices, leading to increased film haze and decreased transparency; on the other hand, the hydrophobic ligands on the surface of traditional nanomaterials have poor compatibility with polar polymer matrices, resulting in weak interfacial bonding and easy phase separation during film bending, affecting the long-term stability of the device. Furthermore, although polyimide materials are widely used in flexible display fields due to their excellent thermal stability, mechanical properties, and optical transparency, the molecular structure of traditional polyimides is relatively simple, making it difficult to meet the specific requirements for nanomaterial dispersion and interfacial bonding. While the introduction of polyvalent metal ions can modulate the electrical and optical properties of polymers, achieving precise ion distribution along the thickness direction and maintaining structural stability remains a technical challenge.

[0004] As a novel type of luminescent material, alloy nanomaterials can effectively reduce internal lattice stress and improve luminescence efficiency and stability through their continuously varying gradient structure. However, there is still a lack of effective technical means to effectively combine this special nanomaterial with a functionalized polymer matrix while maintaining its structural integrity and luminescence performance.

[0005] Therefore, how to solve the problems of nanomaterial dispersion, interfacial compatibility and optical performance regulation through systematic design of material structure, and achieve synergistic improvement of transparency, flexibility and light modulation performance, is a technical problem that urgently needs to be solved in the current research field of flexible transparent display thin film materials.

[0006] Therefore, this invention is proposed. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a flexible and transparent display film material. The aim is to address the problems of poor dispersion of nanomaterials, insufficient compatibility with polymer matrix interfaces, and difficulty in precisely controlling optical properties in existing flexible display films.

[0008] In order to achieve the objective of this invention, the following technical solution is adopted: This invention provides a flexible and transparent display film material, comprising a polymer matrix layer and light-modulating microparticles dispersed within the polymer matrix layer; wherein the polymer matrix layer is obtained by copolymerization of an aromatic dianhydride monomer, an aromatic diamine monomer with a nitrogen-containing heterocyclic structure, and a diamine monomer with flexible side chains; the polymer matrix layer also contains polyvalent metal ions, the concentration of which is gradient distributed along the thickness direction of the polymer matrix layer; The light-modulated microparticles are nanomaterials with a core-shell structure. The core is an inorganic alloy material with continuously varying composition along the radial direction, and the shell is an inorganic semiconductor material layer. The outer surface of the shell contains an organic ligand layer with active functional groups.

[0009] Furthermore, the aromatic dianhydride monomer is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, or benzophenone dianhydride; the aromatic diamine monomer containing a nitrogen-containing heterocyclic structure is selected from at least one of a diamine containing a pyridine ring, a diamine containing a pyrimidine ring, or a diamine containing a triazine ring; the diamine monomer containing a flexible side chain is an aromatic diamine whose side chain contains polyethylene oxide segments, polydimethylsiloxane segments, or polyethylene glycol segments.

[0010] Furthermore, the multivalent metal ion is Zn. 2+ Ca 2+ Al 3+ Cu 2+ or Ni 2+ At least one of them.

[0011] Furthermore, the concentration gradient of the polyvalent metal ions in the polymer matrix layer along the thickness direction is continuously decreasing from the first surface in contact with the solution containing polyvalent metal ions to the opposite second surface, and the ion concentration at the first surface is 1.5-3 times that at the second surface; the average mass fraction of the polyvalent metal ions in the polymer matrix layer is 0.05%-3%.

[0012] Furthermore, the core of the nanomaterial is CdSe. X S 1-X or Zn X Cd 1-X Se alloy material, wherein the X value changes continuously from the core center to the core surface, and the range is 0.1-0.9.

[0013] Furthermore, the nanomaterial has a particle size of 5-10 nm, and the content of the nanomaterial in the polymer matrix layer is 0.01-5.0 wt%.

[0014] Furthermore, the inorganic semiconductor material layer is a wide bandgap inorganic semiconductor material, the bandgap width of which is greater than the bandgap width of the core surface region adjacent to the shell layer; the inorganic semiconductor material layer is selected from ZnS, CdS or ZnSe; the thickness of the inorganic semiconductor material layer is 0.5-2nm.

[0015] Furthermore, the active functional groups in the organic ligand layer are selected from amino, carboxyl, thiol, or epoxy groups.

[0016] The present invention also provides a method for preparing the flexible transparent display thin film material as described above, comprising the following steps: Aromatic dianhydride monomers, aromatic diamine monomers with nitrogen-containing heterocyclic structures, and diamine monomers with flexible side chains are dissolved in an organic solvent and reacted under an inert atmosphere to obtain a polyamic acid solution. Nanomaterials with a core-shell structure are added to the polyamic acid solution, stirred and dispersed evenly, and then degassed under vacuum to obtain a film-forming solution; The film-forming solution is coated onto a clean glass substrate to form a wet film, and then placed in an oven for pre-drying at 60-80°C for 1-3 hours to obtain a gel-state film. The glass substrate containing the gel-like film is immersed in a treatment solution containing polyvalent metal ions and soaked at 35-45°C for 0.5-1.0 hours. Remove the soaked gel film along with the glass substrate and place it in an oven. Treat it at 100-120℃ for 1-2 hours, then raise the temperature to 150-200℃ for 2-4 hours. Allow it to cool naturally to room temperature and peel it off from the glass substrate to obtain the final product.

[0017] Furthermore, in step S4, the solution containing polyvalent metal ions is an acetate, chloride, or nitrate solution selected from zinc, calcium, aluminum, copper, or nickel, with a concentration of 0.01-0.5 mol / L; the electric field strength is 10-100 V / cm, and the application time is 1-30 minutes.

[0018] Furthermore, the preparation method of the nanomaterial with the core-shell structure is as follows: Preparation of alloy nanoparticles; The alloy nanoparticles are dispersed in an organic solvent, and a wide-bandgap inorganic semiconductor material layer is deposited in situ on the surface of the alloy nanoparticles at 80-120°C. The coated nanoparticles are reacted with small organic molecules or short-chain polymers containing amino, carboxyl, thiol or epoxy groups in an organic solvent for 2-12 hours. After precipitation, centrifugation and washing, nanomaterials with core-shell structures containing active functional groups on the surface are obtained.

[0019] The present invention has the following technical effects: (1) This application achieves a synergistic improvement in mechanical properties, optical transparency and functional compatibility through the optimized design of polymer matrix molecular structure.

[0020] (2) This application achieves spatially precise control of the mechanical, electrical and optical properties of thin films by constructing a gradually varying ion concentration distribution in the thickness direction in the polymer matrix.

[0021] (3) This application has achieved breakthrough results in terms of luminescence efficiency, stability and matrix compatibility through the fine design of the core-shell structure of nanomaterials. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] In a first aspect, this application provides a flexible and transparent display film material, comprising a polymer matrix layer and light-modulating microparticles dispersed within the polymer matrix layer; wherein the polymer matrix layer is obtained by copolymerization of an aromatic dianhydride monomer, an aromatic diamine monomer with a nitrogen-containing heterocyclic structure, and a diamine monomer with flexible side chains; the polymer matrix layer further comprises multivalent metal ions, the concentration of which is gradient distributed along the thickness direction of the polymer matrix layer; The light-modulated microparticles are nanomaterials with a core-shell structure. The core is an inorganic alloy material with continuously varying composition along the radial direction, and the shell is an inorganic semiconductor material layer. The outer surface of the shell contains an organic ligand layer with active functional groups.

[0024] In some embodiments, the aromatic dianhydride monomer is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, or benzophenone dianhydride; the aromatic diamine monomer containing a nitrogen-containing heterocyclic structure is selected from at least one of a diamine containing a pyridine ring, a diamine containing a pyrimidine ring, or a diamine containing a triazine ring; the diamine monomer containing a flexible side chain is any one or more of an aromatic diamine whose side chain contains polyethylene oxide segments, polydimethylsiloxane segments, or polyethylene glycol segments.

[0025] In some embodiments, the multivalent metal ion is Zn. 2+ Ca 2+ Al 3+ Cu 2+ or Ni 2+ At least one of them.

[0026] In some embodiments, the concentration gradient of the polyvalent metal ions in the thickness direction of the polymer matrix layer is a continuously decreasing distribution from a first surface in contact with the solution containing polyvalent metal ions to the opposite second surface, and the ion concentration at the first surface is 1.5-3 times that at the second surface; the average mass fraction of the polyvalent metal ions in the polymer matrix layer is 0.05%-3%.

[0027] In some embodiments, the core of the nanomaterial is CdSe. X S 1-X or Zn X Cd 1-X Se alloy material, wherein the X value changes continuously from the core center to the core surface, and the range is 0.1-0.9.

[0028] In some embodiments, the nanomaterial has a particle size of 5-10 nm and the content of the nanomaterial in the polymer matrix layer is 0.01-5.0 wt%.

[0029] In some embodiments, the inorganic semiconductor material layer is a wide bandgap inorganic semiconductor material, the bandgap width of which is greater than the bandgap width of the core surface region adjacent to the shell layer; the inorganic semiconductor material layer is selected from ZnS, CdS or ZnSe; the thickness of the inorganic semiconductor material layer is 0.5-2nm.

[0030] In some embodiments, the active functional groups in the organic ligand layer are selected from amino, carboxyl, thiol, or epoxy groups.

[0031] Secondly, this application also provides a method for preparing the above-mentioned flexible transparent display thin film material, comprising the following steps: Aromatic dianhydride monomers, aromatic diamine monomers with nitrogen-containing heterocyclic structures, and diamine monomers with flexible side chains are dissolved in an organic solvent and reacted under an inert atmosphere to obtain a polyamic acid solution. Nanomaterials with a core-shell structure are added to the polyamic acid solution, stirred and dispersed evenly, and then degassed under vacuum to obtain a film-forming solution; The film-forming solution is coated onto a clean glass substrate to form a wet film, and then placed in an oven for pre-drying at 60-80°C for 1-3 hours to obtain a gel-state film. The glass substrate containing the gel-like film is immersed in a treatment solution containing polyvalent metal ions and soaked at 35-45°C for 0.5-1.0 hours. Remove the soaked gel film along with the glass substrate and place it in an oven. Treat it at 100-120℃ for 1-2 hours, then raise the temperature to 150-200℃ for 2-4 hours. Allow it to cool naturally to room temperature and peel it off from the glass substrate to obtain the final product.

[0032] In some embodiments, the preparation method of the core-shell structured nanomaterial is as follows: Preparation of alloy nanoparticles; The alloy nanoparticles are dispersed in an organic solvent, and a wide-bandgap inorganic semiconductor material layer is deposited in situ on the surface of the alloy nanoparticles at 80-120°C. The coated nanoparticles are reacted with small organic molecules or short-chain polymers containing amino, carboxyl, thiol or epoxy groups in an organic solvent for 2-12 hours. After precipitation, centrifugation and washing, nanomaterials with core-shell structures containing active functional groups on the surface are obtained.

[0033] The following is a detailed explanation using specific embodiments: Example 1 A method for preparing a flexible and transparent display thin film material, comprising the following specific steps: 1. Preparation of nanomaterials with core-shell structure (1) Preparation of alloy nanoparticles: Under nitrogen protection, 0.2 mmol cadmium oxide (CdO) and 0.8 mmol zinc oxide (ZnO) were mixed with 5 mL oleic acid (OA) and 10 mL octadecene (ODE), heated to 150 °C to degas for 30 minutes, and then heated to 300 °C to completely dissolve the solid. Subsequently, 0.5 mmol of selenium powder (Se) was dissolved in 2 mL of trioctylphosphine (TOP) and rapidly injected into the reaction system. The reaction was carried out at 280 °C for 10 minutes to obtain CdZnSe alloy nanoparticles. The molar ratio of Zn to Cd in the nanoparticles was continuously changed from 0.1:0.9 to 0.9:0.1 from the center to the outer surface by controlling the reaction time.

[0034] After the reaction was completed and cooled to room temperature, acetone was added to precipitate the particles, and centrifugation was performed to obtain alloy nanoparticles with a particle size of 8 nm.

[0035] (2) Shell covering: The above alloy nanoparticles were dispersed in 10 mL LODE, and 0.5 mmol Zn(OAc)₂ and 0.5 mmol sulfur powder (dissolved in 1 mL TOP) were added. The mixture was reacted at 100 °C for 30 minutes to deposit a ZnS shell layer with a thickness of 1.5 nm in situ. After centrifugation and washing, the core-shell structured nanomaterial was obtained.

[0036] (3) Surface ligand exchange: The above-mentioned core-shell nanomaterials were dispersed in 10 mL of toluene, and 0.2 mL of mercaptoethylamine was added. The mixture was stirred at 60 °C for 2 hours. After precipitation, centrifugation, and washing three times with toluene, core-shell nanomaterials with amino-active functional groups on the surface were obtained, with a final particle size of approximately 9.5 nm.

[0037] 2. Preparation of raw materials for the polymer matrix layer and polyamic acid solution In a dry three-necked flask, under nitrogen protection, add the following in sequence: Aromatic dianhydride monomer: Pyromellitic dianhydride (PMDA, 5.0 mmol, 1.09 g) Aromatic diamine monomers with nitrogen-containing heterocyclic structures: 2,6-diaminopyridine (DAP, 2.5 mmol, 0.27 g) Diamine monomers with flexible side chains: Aromatic diamines (2.5 mmol, approximately 1.0 g) with polyethylene glycol (PEG, molecular weight approximately 400) as the side chain. Anhydrous N,N-dimethylacetamide (DMAc, 30 mL) was added and dissolved by stirring at room temperature. The mixture was then reacted in an ice-water bath for 8 hours to obtain a polyamic acid solution with a solid content of approximately 8%.

[0038] 3. Preparation of film-forming solution The prepared nanomaterials were added to the above polyamic acid solution at an amount of 2.5 wt% of the polymer matrix. The mixture was stirred vigorously for 2 hours until it was uniformly dispersed, and then vacuum degassed for 30 minutes to obtain the film-forming solution.

[0039] 4. Film formation and ion gradient treatment Coating: The film-forming solution is uniformly coated on a clean glass substrate, and the wet film thickness is about 300 μm.

[0040] Pre-drying: Place in an oven and pre-dry at 60℃ for 3 hours.

[0041] Ion immersion: Immersing a glass substrate containing a gel-like thin film into an immersion solution containing polyvalent metal ions (Zn²⁺). + Soak in a treatment solution containing 0.1 mol / L zinc acetate aqueous solution at 35°C for 1.0 hour.

[0042] Thermal imidization: Take out the film / glass plate, place it in an oven, treat it at 100°C for 2 hours, then raise the temperature to 200°C for 2 hours, and peel it off from the glass plate after natural cooling to obtain a flexible and transparent display film material.

[0043] Comparative Example 1 Add 0.2 mmol of cadmium oxide, 2 mL of oleic acid, and 10 mL of octadecene (ODE) to a three-necked flask.

[0044] Under nitrogen protection, the solution is heated to 280°C to dissolve the cadmium salt, forming a clear solution.

[0045] Quickly inject 2 mL of a trioctylphosphine (TOP) solution containing 2.0 mmol of trioctylphosphine selenium (TOPSe).

[0046] The reaction was carried out at this temperature for 5 minutes to obtain CdSe nanomaterials.

[0047] After the reaction was complete, the mixture was allowed to cool naturally to room temperature. Excess acetone was added, and the precipitate was centrifuged and discarded. The supernatant was then redispersed in toluene, and the purification process was repeated three times. The resulting nanomaterials had a particle size of approximately 3-5 nm.

[0048] Ligand processing: The purified CdSe nanomaterials were dispersed in 10 mL of toluene, and 10 mL of an aqueous solution containing 0.1 g of cysteine ​​was added. The mixture was stirred vigorously overnight at room temperature.

[0049] The nanomaterials were transferred from the toluene phase to the aqueous phase, the aqueous phase was separated, and CdSe nanomaterials with simple surface modifications of carboxyl / amino groups were obtained. After vacuum drying, they were ready for use.

[0050] Preparation of polyamic acid solution: Add the following ingredients sequentially to a 250 mL three-necked flask equipped with a mechanical stirrer: 50 mL of N,N-dimethylacetamide (DMAc) dried with molecular sieves; 2.18 g (10 mmol) of pyromellitic dianhydride (PMDA); and 2.00 g (10 mmol) of 4,4'-diaminodiphenyl ether (ODA, a conventional aromatic diamine).

[0051] The polymerization reaction was stirred for 8 hours under ice-water bath conditions to obtain a viscous polyamic acid solution.

[0052] Preparation of conventional polyimide films: The above polyamic acid solution was uniformly coated onto a clean glass substrate using a blade coating method.

[0053] Place the product in a vacuum oven and perform thermal imidization according to a stepped temperature increase program: 60℃ / 2h, 120℃ / 1h, 180℃ / 1h, 250℃ / 1h.

[0054] After cooling, the film is peeled off from the glass substrate to obtain a transparent conventional polyimide film.

[0055] Coating of nanomaterial layers: The prepared aqueous CdSe nanomaterials were redispersed in ethanol to prepare a dilute solution (approximately 0.1 mg / mL).

[0056] The nanomaterial solution was coated onto the surface of the prepared polyimide film by spin coating (1000 rpm, 30 seconds).

[0057] Vacuum drying at 60°C for 30 minutes allows the solvent to evaporate, forming a thin layer of nanomaterials.

[0058] Post-processing: The prepared bilayer structure film was vacuum dried at 60°C for 2 hours to obtain the final transparent display film material.

[0059] Experimental Example 1 Experimental Example: Performance Comparison Test of Flexible Transparent Display Films Experimental objective: To place the four flexible transparent display film materials prepared in Example 1 and Comparative Example 1 in a working environment simulating a real display device, and to systematically evaluate their key performance indicators, so as to verify the advantages of the materials provided in this application in terms of luminous efficiency, stability and optical uniformity.

[0060] Experimental materials grouping: Group 1: The thin film prepared in Example 1; Group 2: Thin films prepared in Comparative Example 1; Experimental procedures and test items: Optical performance testing: Test method: Two sets of films were cut to the same size (2cm × 2cm). The photoluminescence (PL) spectrum of the films was measured using a fluorescence spectrophotometer, and the emission peak position and full width at half maximum (FWHM) were recorded. The average transmittance of the films in the visible light region (400-700nm) was measured using a UV-Vis spectrophotometer.

[0061] Stability and aging tests: Test method: The two sets of films were placed in a constant temperature and humidity chamber at 85°C and 85% relative humidity (double 85 test) and under continuous ultraviolet light (365nm, intensity adjustable). The samples were taken out every 24 hours, and the change in their PL intensity was measured. The time (T50) when the luminescence intensity decayed to 50% of the initial value was recorded.

[0062] Flexible bending test: Test method: Fix two sets of films on a test fixture with an adjustable bending radius. Starting from the initial flat state, gradually decrease the bending radius until the film cracks or irreversible decay of luminescence occurs. Record the critical bending radius. Simultaneously, perform dynamic bending (e.g., 1000 times) at a fixed bending radius (e.g., 5 mm) and compare the PL strength retention rate before and after bending.

[0063] Electric field response and luminescence uniformity test: Test method: Two sets of thin films were placed in a simple electroluminescence testing device (with transparent electrodes clamped). Alternating electric fields of different intensities were applied, and the luminescence initiation voltage and luminescence intensity of the films were observed. Simultaneously, images of the films luminescent under the electric field were recorded using a microscope or CCD camera, and the density and uniformity of the luminescent spots were evaluated using image analysis software.

[0064] The final test results are shown in Table 1 below.

[0065] Table 1 Test Results As shown in Table 1, based on the system test results of the above experimental examples, it is clear that the thin film material of Example 1 prepared using the technical solution of this application exhibits significant advantages over the traditional comparative examples in all key performance indicators. From the most crucial optical performance perspective, the luminous intensity of Example 1 is generally higher than that of the comparative examples, the full width at half maximum (FWHM) is narrowed to within 30 nanometers, while the average transmittance remains above 91%.

[0066] In terms of environmental stability, Example 1 has a more prominent advantage. In the rigorous double 85 aging and ultraviolet light test, its luminescence intensity decayed to half in more than 500 hours, while Comparative Example 1 could only maintain it for less than 50 hours.

[0067] In terms of mechanical flexibility, Example 1 can withstand a critical bending radius of less than one millimeter and still maintains more than 95% of its luminescence intensity after thousands of dynamic bends. In contrast, Comparative Example 1 uses traditional shell-less cadmium sulfide nanomaterials composited with conventional polyimide films via surface spin coating. This double-layer structure inherently suffers from weak interfacial bonding, easy agglomeration of nanomaterials, and susceptibility to environmental oxidation. In addition, the lack of functional design in the matrix material results in Example 1 lagging far behind Example 1 in all dimensions, including luminescence efficiency, stability, flexibility, and uniformity, with an overall score of less than half that of the latter.

[0068] In summary, this application successfully overcomes the inherent contradictions between luminous efficiency, stability, and flexibility in traditional materials. The prepared thin film material combines high brightness, high transmittance, ultra-long lifespan, excellent flexibility, and excellent luminous uniformity, providing a practical material solution for realizing high-performance flexible transparent display devices and demonstrating great application potential and technological advancement.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A flexible, transparent display film material, characterized in that, The invention comprises a polymer matrix layer and light-modulating microparticles dispersed within the polymer matrix layer; wherein the polymer matrix layer is prepared by copolymerization of an aromatic dianhydride monomer, an aromatic diamine monomer with a nitrogen-containing heterocyclic structure, and a diamine monomer with flexible side chains; the polymer matrix layer also contains polyvalent metal ions, the concentration of which is gradient distributed along the thickness direction of the polymer matrix layer; The light-modulated microparticles are nanomaterials with a core-shell structure. The core is an inorganic alloy material with continuously varying composition along the radial direction, and the shell is an inorganic semiconductor material layer. The outer surface of the shell contains an organic ligand layer with active functional groups.

2. The flexible transparent display film material according to claim 1, characterized in that, The aromatic dianhydride monomer is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, or benzophenone dianhydride; the aromatic diamine monomer containing a nitrogen-containing heterocyclic structure is selected from at least one of a diamine containing a pyridine ring, a diamine containing a pyrimidine ring, or a diamine containing a triazine ring; the diamine monomer containing a flexible side chain is any one or more of an aromatic diamine whose side chain contains polyethylene oxide segments, polydimethylsiloxane segments, or polyethylene glycol segments.

3. The flexible transparent display film material according to claim 1, characterized in that, The multivalent metal ion is Zn. 2+ Ca 2+ Al 3+ Cu 2+ or Ni 2+ At least one of them.

4. The flexible transparent display film material according to claim 3, characterized in that, The concentration gradient of the polyvalent metal ions in the polymer matrix layer along the thickness direction is continuously decreasing from the first surface in contact with the solution containing polyvalent metal ions to the opposite second surface, and the ion concentration at the first surface is 1.5-3 times that at the second surface; the average mass fraction of the polyvalent metal ions in the polymer matrix layer is 0.05%-3%.

5. The flexible transparent display film material according to claim 1, characterized in that, The core of the nanomaterial is CdSe. X S 1-X or Zn X Cd 1-X Se alloy material, in which the X value changes continuously from the core center to the core surface, with a range of 0.1-0.

9.

6. The flexible transparent display film material according to claim 5, characterized in that, The nanomaterial has a particle size of 5-10 nm and its content in the polymer matrix layer is 0.01-5.0 wt%.

7. The flexible transparent display film material according to claim 1, characterized in that, The inorganic semiconductor material layer is a wide bandgap inorganic semiconductor material, and its bandgap width is greater than the bandgap width of the core surface region adjacent to the shell layer; the inorganic semiconductor material layer is selected from ZnS, CdS or ZnSe; the thickness of the inorganic semiconductor material layer is 0.5-2nm.

8. The flexible transparent display film material according to claim 1, characterized in that, The active functional groups in the organic ligand layer are selected from amino, carboxyl, thiol, or epoxy groups.

9. A method for preparing a flexible transparent display thin film material as described in any one of claims 1-8, characterized in that, Includes the following steps: Aromatic dianhydride monomers, aromatic diamine monomers with nitrogen-containing heterocyclic structures, and diamine monomers with flexible side chains are dissolved in an organic solvent and reacted under an inert atmosphere to obtain a polyamic acid solution. Nanomaterials with a core-shell structure are added to the polyamic acid solution, stirred and dispersed evenly, and then degassed under vacuum to obtain a film-forming solution; The film-forming solution is coated onto a clean glass substrate to form a wet film, and then placed in an oven for pre-drying at 60-80°C for 1-3 hours to obtain a gel-state film. The glass substrate containing the gel-like film is immersed in a treatment solution containing polyvalent metal ions and soaked at 35-45°C for 0.5-1.0 hours. Remove the soaked gel film along with the glass substrate and place it in an oven. Treat it at 100-120℃ for 1-2 hours, then raise the temperature to 150-200℃ for 2-4 hours. Allow it to cool naturally to room temperature and peel it off from the glass substrate to obtain the final product.

10. The preparation method according to claim 9, characterized in that, The preparation method of the nanomaterial with the core-shell structure is as follows: Preparation of alloy nanoparticles; The alloy nanoparticles are dispersed in an organic solvent, and a wide-bandgap inorganic semiconductor material layer is deposited in situ on the surface of the alloy nanoparticles at 80-120°C. The coated nanoparticles are reacted with small organic molecules or short-chain polymers containing amino, carboxyl, thiol or epoxy groups in an organic solvent for 2-12 hours. After precipitation, centrifugation and washing, nanomaterials with core-shell structure containing active functional groups on the surface are obtained.

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