A method for preparing a display film of stimulated light

Abstract

The application provides a preparation method of a stimulated light display film, and belongs to the technical field of display film preparation, and aims to solve the problem that high-temperature annealing is incompatible with flexible substrates in the preparation of existing light-emitting films. The preparation method comprises the following steps: preparing a self-passivation type vapor transmission mineralization additive containing an oligomer type mixed ammonium halide complex; compounding the additive with a metal oxide sol; performing spin coating and pre-solidification to form a dry gel film; under the action of saturated solvent vapor and a micro-negative pressure environment, high-crystalline-quality perovskite nanocrystals are in-situ grown in the oxide matrix at a low temperature through an integrated vapor permeation-crystallization-passivation process; and ultraviolet light crosslinking is used for reinforcement. The prepared light-emitting film has the advantages of high photoluminescence quantum yield, narrow emission full width at half maximum, high color purity, good light-emitting uniformity and excellent hygrothermal stability, and is suitable for high-performance electroluminescent display devices or high-color-gamut photoluminescence color conversion layers.

Description

Technical Field

[0001] This invention relates to the field of display film preparation technology, and in particular to a method for preparing an excited-light display film. Background Technology

[0002] Metal halide perovskite nanocrystals (PeNCs), with their extremely high photoluminescence quantum yield, precisely tunable emission wavelength, high color purity due to their extremely narrow emission half-width at half-maximum, and excellent charge transport properties, are widely recognized as a core luminescent material with great potential in next-generation display technologies, including micro-LEDs, electroluminescent diodes, and high color gamut liquid crystal display backlights. However, to realize their commercial application, two long-standing key obstacles must be overcome: first, the intrinsic instability of the material itself to moisture, oxygen, heat, and photostress easily leads to luminescence quenching and performance degradation; second, the fabrication process of high-quality PeNCs thin films is often incompatible with low-cost, large-area, and especially flexible display manufacturing processes. To improve stability, the mainstream technical approach is to encapsulate PeNCs in an inorganic oxide matrix. However, traditional methods are generally caught in a trade-off between encapsulation and quenching. For example, in the sol-gel method, perovskite precursors are directly mixed with metal alkoxides. During the subsequent high-temperature annealing (typically >300°C) required to fully densify the oxide network, the intense thermal stress and chemical reactions severely damage the crystal integrity of PeNCs and generate numerous surface defects, leading to a sharp decline in luminescence efficiency. Another method, post-immersion immersion, involves first preparing a porous oxide film and then immersing it in a PeNCs dispersion. While this avoids high-temperature damage, the PeNCs are only physically adsorbed within the pores, resulting in uneven distribution, low loading, and weak binding to the matrix. This makes them prone to leakage and aggregation in subsequent processes or use, leading to uneven film luminescence, poor long-term reliability, and the inability to achieve controllable growth of PeNCs in three-dimensional space. More advanced gas-phase assisted or vapor treatment methods offer the possibility of low-temperature preparation, but existing technologies still have significant limitations. Simply using small-molecule vapors such as methylamine salts to treat the wet precursor film can induce crystallization at lower temperatures, but it is difficult to control the precise and uniform doping of multiple cations and mixed halogens, which is crucial for obtaining efficient, stable, and ideal emission wavelengths. Furthermore, the steam process is typically rapid and uncontrollable, easily leading to uneven crystallization and coarse grains. It also lacks a mechanism for simultaneously passivating surface defects during crystallization, leaving significant room for improvement in the film's efficiency and stability. Simultaneously, the interfacial stress caused by the mismatch in thermal expansion coefficients between the oxide matrix and PeNCs is also a crucial factor affecting the film's mechanical stability and long-term durability, a concern that current technologies have not adequately addressed. Therefore, developing a novel method for preparing stimulated light display films has become an urgent industry need. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing light-emitting display films that addresses the problems in existing technologies using perovskite materials to prepare luminescent films. These problems include excessively high annealing temperatures required to achieve high-quality crystallization and high stability, incompatibility with flexible display manufacturing processes, poor crystallization quality at low temperatures, uneven doping of multi-component components, difficulty in balancing luminous efficiency and stability, and the lack of in-situ defect passivation and interface stress buffering mechanisms during the process. These problems collectively make it difficult for the prepared perovskite luminescent films to simultaneously meet the stringent requirements of next-generation high-performance, high-reliability displays for low-temperature processing, high luminous efficiency, high color purity, excellent uniformity, and long-term stability. The specific technical solution of this invention is as follows: This invention provides a method for preparing an excited-light display thin film, the method comprising the following steps: S1. Preparation of steam transport mineralization aid; S2. Preparation of composite precursor solution: Tetraethyl orthosilicate is added to anhydrous ethanol and stirred. Under ice-water bath and stirring conditions, a mixture of deionized water and acetic acid is added dropwise. Low-temperature stirring is continued to obtain silica sol. The ice bath is removed, the mixture is restored to room temperature, a steam transport mineralization aid is added, the temperature is raised and stirred to obtain composite precursor solution. S3. Gradient heat treatment: After the composite precursor solution is formed into a film, it is placed on a hot plate for gradient heat treatment to obtain a pre-cured dry gel film. S4. Steam-assisted annealing: The pre-cured dry gel film is placed in a closed reaction chamber for steam-assisted annealing. The reaction chamber is provided with a saturated vapor environment of N-methyl-2-pyrrolidone solvent. The annealing process is carried out by programmed temperature rise, and the film is taken out after cooling. S5. Ultraviolet light irradiation: The film processed in step S4 is irradiated under ultraviolet light to obtain an excited light display film.

[0004] Further, in step S2, the raw materials in the composite precursor solution include, by weight, 7-10 parts of tetraethyl orthosilicate, 12-15 parts of anhydrous ethanol, 2 parts of deionized water, 0.03-0.05 parts of acetic acid, and 7-8 parts of steam transport mineralization aid. The specific process of step S2 is as follows: Tetraethyl orthosilicate is added to anhydrous ethanol and stirred at 25°C and 300 rpm for 20-30 minutes; a mixture of deionized water and acetic acid is added dropwise over 15-20 minutes while stirring in an ice-water bath at 0-5°C; after the addition is complete, the mixture is stirred at 3-5°C for 40-60 minutes to obtain silica sol; the ice bath is removed, the temperature is restored to 25°C, a steam transport mineralization aid is added while stirring, the mixture is heated to 38-40°C, and stirred at 600 rpm for 3 hours to obtain a composite precursor solution.

[0005] Furthermore, step S3 gradient heat treatment includes three stages: the first stage, holding at 65-75°C for 100-120 seconds; the second stage, holding at 140-150°C for 160-180 seconds; and the third stage, holding at 170-180°C for 50-60 seconds.

[0006] Further, step S3, gradient heat treatment, includes: holding at 70-75°C for 110-120 seconds; holding at 145-150°C for 170-180 seconds; and holding at 175-180°C for 55-60 seconds.

[0007] Further, in step S4, the initial temperature of the programmed temperature rise is 90-100°C, the final temperature is 125-135°C, the heating rate is 2-2.5°C / min, and the temperature is maintained at the final temperature for 18-25 minutes; the absolute pressure in the reaction chamber is controlled at 5 kPa; the initial temperature of the programmed temperature rise is 95-100°C, the temperature is increased to 130-135°C at a rate of 2°C / min, and the temperature is maintained at the final temperature for 22-25 minutes.

[0008] Furthermore, in step S5, the wavelength of the ultraviolet light is 365 nm, the irradiation time is 5 minutes, and the intensity of the ultraviolet light is 40-50 mW / cm².

[0009] Furthermore, the raw materials for preparing the steam transport mineralization aid include, by weight: 62-70 parts of N-methyl-2-pyrrolidone, 15-20 parts of oligomeric mixed ammonium halide complex, 4-7 parts of dioctyl ammonium iodide, 2-5 parts of surface amino-modified titanium dioxide nanorods, and 1-3 parts of poly(ethylene-alt-maleic anhydride).

[0010] Furthermore, the preparation method of the steam transport mineralization aid includes the following steps: S1a, Preparation of oligomeric mixed ammonium halide complex powder; S1b, Preparation of surface amino-modified titanium dioxide nanorod powder; S1c, Compounding: N-methyl-2-pyrrolidone is stirred and heated at 60°C and 400 rpm. Oligomeric mixed ammonium halide complex powder, dioctyl ammonium iodide, amino-modified titanium dioxide nanorod powder, and poly(ethylene-alt-maleic anhydride) are added. After each component is added, the mixture is stirred at 60°C and 400 rpm for 30 minutes. The temperature is raised to 70-80°C, the stirring rate is increased to 800 rpm, and the mixture is stirred for 3.5-4 hours to form a viscous liquid. After filtration, the steam transport mineralization aid is obtained.

[0011] Further, the preparation of oligomeric mixed ammonium halide complex powder includes: dissolving formamidinium iodine, methylamine bromide, cesium bromide, lead iodide, and lead bromide in N,N-dimethylformamide under an argon atmosphere, stirring at room temperature and 500 rpm for 12 hours, adding anhydrous diethyl ether, stirring at 800 rpm, and allowing to stand at -20°C for 4 hours, collecting the precipitate by centrifugation, washing, and drying under vacuum conditions of 40-50°C and pressure below 10 Pa for 24 hours to obtain oligomeric mixed ammonium halide complex powder.

[0012] Further, the preparation of surface amino-modified titanium dioxide nanorod powder includes: dispersing titanium dioxide nanorod powder in anhydrous toluene, sonicating for 30 minutes, adding 3-aminopropyltriethoxysilane, refluxing and stirring at 110°C for 24 hours under nitrogen protection, centrifuging, washing, and drying to obtain surface amino-modified titanium dioxide nanorod powder.

[0013] The beneficial effects of this invention are as follows: The method for preparing stimulated light display thin films provided by this invention combines four functional components—oligomeric mixed ammonium halide complexes, vapor-phase dynamic passivating agents, surface-amino-modified titanium dioxide nanorods, and polymer interface stabilizers—and employs a two-step process of pre-assembly-vapor permeation crystallization. This achieves synergistic effects among the components, jointly solving the problem of the incompatibility between low-temperature preparation, high luminous efficiency, and high stability of perovskite luminescent thin films. Specifically, the oligomeric complexes, as precursors for uniformly doped at the molecular level, are the foundation for achieving high-quality crystallization and ideal emission wavelengths at low temperatures; dioctylammonium iodide, as a vapor-phase passivating agent, enables simultaneous repair of defects during crystallization, which is key to obtaining high photoluminescence quantum yield (PLQY); amino-modified nanorods, as heterogeneous nucleation centers, guide the uniform and refined growth of grains, which is the core for obtaining high color purity and excellent film uniformity; and the polymer interface stabilizer, by constructing a flexible buffer layer, effectively relaxes interfacial stress, ensuring the film's excellent environmental stability. The performance gradients of Examples 1-3 and the systematic degradation of Comparative Examples 1-6 jointly demonstrate that the absence of any component or alteration of its synergistic effect leads to a significant decrease in performance. Only when all four components work synergistically under the specific ratios and processes set in this invention can the optimal overall performance shown in Example 1 be achieved: high PLQY (91.5%), narrow half-width at half-maximum (18.2 nm), high uniformity (non-uniformity 3.1%), and high stability (94.5% retention rate after 500 hours at 85°C / 85%RH). The pre-synthesized oligomeric mixed ammonium halide complex involved in this invention can controllably and uniformly release the constituent ions of perovskite upon heating, fundamentally ensuring the atomic-level mixing uniformity of the multi-components during low-temperature crystallization and avoiding component segregation caused by differences in diffusion rates of various solid or solution precursors in conventional methods. Furthermore, during the vapor permeation crystallization stage, dioctammonium iodide and the oligomeric complex co-vaporize and diffuse. The sterically hindered organic cations of dioctylammonium iodide can competitively adsorb onto the surface of newly formed perovskite nanocrystals, instantly filling halogen vacancies and other defect states. This in-situ passivation mechanism in the gas phase maximally suppresses the formation of non-radiative recombination channels during crystal growth, which is the direct reason for the high luminescence efficiency. Furthermore, the uniformly dispersed amino-modified titanium dioxide nanorods, with their surface -NH2 groups exhibiting strong coordination with the perovskite precursor, effectively lower the nucleation barrier of the perovskite phase and act as heterogeneous nucleation sites to guide the epitaxial growth of perovskite around them. This heterogeneous nucleation guidance makes the crystallization process more controllable, resulting in uniformly sized and densely distributed nanocrystals, thereby improving luminescence uniformity and narrowing the emission spectrum.Ultimately, under heat treatment, the silane ends of the polymer interface stabilizer condense and anchor with the silica matrix, while the flexible polymer segments entangle with the long-chain ligands on the surface of the perovskite nanocrystals. This constructs a flexible buffer interface layer between the hard oxide matrix and the brittle perovskite nanocrystals. This layer effectively absorbs and releases the internal stress caused by the mismatch in their thermal expansion coefficients, preventing the film from cracking or peeling under thermal cycling or environmental stress, thereby significantly improving the film's mechanical integrity and long-term environmental stability. The entire process is completed at a low temperature of ≤135°C, meeting the temperature resistance requirements of flexible plastic substrates. Detailed Implementation

[0014] The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] The titanium dioxide nanorod powder involved in this invention is YT-TiO2-N2 from Ningbo Yutian Materials Technology Co., Ltd., the 3-aminopropyltriethoxysilane is KH-550 coupling agent from Jiangxi Chenguang, and the poly(ethylene-alt-maleic anhydride) is Sigma-Aldrich, catalog number 188050 (average Mw 100,000-500,000, powder).

[0016] Example 1 This embodiment provides a raw material for preparing a light-excited display film, which, by weight, comprises: 10 parts tetraethyl orthosilicate, 15 parts anhydrous ethanol, 2 parts deionized water, 0.05 parts acetic acid, and 8 parts vapor transport mineralization agent.

[0017] The raw materials for preparing the steam transport mineralization aid include, by weight, 65 parts N-methyl-2-pyrrolidone, 20 parts oligomeric mixed ammonium halide complex, 7 parts dioctammonium iodide, 5 parts surface amino-modified titanium dioxide nanorods, and 3 parts poly(ethylene-alt-maleic anhydride).

[0018] The preparation method of the steam transport mineralization aid includes the following steps: Step a: Preparation of oligomeric mixed ammonium halide complexes: 0.8 mmol formamidinium iodide, 0.15 mmol methylamine bromide, 0.5 mmol cesium bromide, 1 mmol lead iodide, 0.1 mmol lead bromide, and 20 g N,N-dimethylformamide were added under an argon atmosphere. The mixture was stirred at 500 rpm for 12 hours at room temperature. 50 mL of anhydrous diethyl ether was added, and the mixture was stirred at 800 rpm. The mixture was allowed to stand at -20°C for 4 hours, then centrifuged at 8000 rpm for 10 minutes at 4°C. The precipitate was collected, washed three times with anhydrous diethyl ether, and dried in a vacuum oven at 50°C and 8 Pa for 24 hours to obtain the oligomeric complex. 20 portions by weight were taken for later use.

[0019] Step b: Preparation of surface amino-modified titanium dioxide nanorods: Take 1 part of titanium dioxide nanorod powder and disperse it in 30 parts of anhydrous toluene. Sonicate for 30 minutes, add 3 parts of 3-aminopropyltriethoxysilane, reflux and stir at 110°C for 24 hours under nitrogen protection, centrifuge, wash three times each with toluene and ethanol, and vacuum dry at 60°C to obtain titanium dioxide nanorod powder. Take 5 parts for later use.

[0020] Step c, Compounding: 65 parts by weight of N-methyl-2-pyrrolidone were stirred and heated to 60°C at a stirring speed of 400 rpm. 20 parts by weight of the oligomer complex powder, 7 parts by weight of dioctylammonium iodide, 5 parts by weight of amino-titanium dioxide nanorods, and 3 parts by weight of poly(ethylene-alt-maleic anhydride) were added. For each component added, the mixture was stirred at 60°C and 400 rpm for 30 minutes. After all components were added, the temperature was raised to 80°C, the stirring speed was increased to 800 rpm, and the mixture was stirred for 4 hours to form a dark, viscous liquid. The liquid was then pressure filtered through a 0.1 μm polytetrafluoroethylene membrane in a glove box. The filtrate, used as a steam-transfer mineralization aid, was stored in a brown glass bottle for later use.

[0021] This embodiment also provides a method for preparing an excited-light display film, the method comprising the following steps by weight: Step 1: Add 10 parts by weight of tetraethyl orthosilicate to 15 parts by weight of anhydrous ethanol and stir at 25°C and 300 rpm for 30 minutes. While in an ice-water bath with stirring, add dropwise a mixture of 2 parts by weight of deionized water and 0.5 parts by weight of acetic acid over 20 minutes. Stir at 5°C for 60 minutes to obtain silica sol.

[0022] Remove the ice bath and restore the temperature to 25°C. Add 8 parts by weight of the steam transport mineralization aid prepared above while stirring. Heat the mixture to 40°C and stir at 600 rpm for 3 hours to obtain a composite precursor solution.

[0023] Step 2: Place the spin-coated wet film on a precision temperature-controlled hot plate preheated to 75°C and hold for 120 seconds. Increase the temperature of the hot plate to 150°C and hold for 180 seconds. Increase the temperature to 180°C and hold for 60 seconds. This gradient heat treatment yields a pre-cured dry gel film.

[0024] Step 3: Place the pre-cured film in a sealed reaction chamber. Place a shallow dish containing 2 parts by weight of pure NMP solvent at the bottom of the reaction chamber (to provide a saturated solvent vapor environment). Set the temperature of the film area to 100°C and program the temperature to 135°C at a rate of 2°C / min for 17.5 minutes. Maintain the temperature at 135°C for 25 minutes. Control the pressure in the reaction chamber to a slightly negative pressure of 5 kPa (absolute pressure) using a fine-tuning valve. Cool down to 60°C and remove the film.

[0025] Step 4: Irradiate the thin film under ultraviolet light with a wavelength of 365 nm and an intensity of 50 mW / cm² for 5 minutes to prepare the display thin film.

[0026] Example 2 This embodiment provides a raw material for preparing a light-excited display film, which, by weight, comprises: 8 parts tetraethyl orthosilicate, 13 parts anhydrous ethanol, 2 parts deionized water, 0.04 parts acetic acid, and 8 parts vapor transport mineralization agent.

[0027] The raw materials for preparing the steam transport mineralization aid include, by weight, 62 parts N-methyl-2-pyrrolidone, 18 parts oligomeric mixed ammonium halide complex, 5 parts dioctammonium iodide, 3 parts surface amino-modified titanium dioxide nanorods, and 1.5 parts poly(ethylene-alt-maleic anhydride).

[0028] The preparation method of the steam transport mineralization aid includes the following steps: Step a: Preparation of oligomeric mixed ammonium halide complexes: 0.8 mmol formamidinium iodide, 0.15 mmol methylamine bromide, 0.5 mmol cesium bromide, 1 mmol lead iodide, 0.1 mmol lead bromide, and 20 g N,N-dimethylformamide were added under an argon atmosphere. The mixture was stirred at 500 rpm for 12 hours at room temperature. 50 mL of anhydrous diethyl ether was added, and the mixture was stirred at 800 rpm. The mixture was allowed to stand at -20°C for 4 hours, then centrifuged at 8000 rpm for 10 minutes at 4°C. The precipitate was collected, washed three times with anhydrous diethyl ether, and dried in a vacuum oven at 45°C and <10 Pa for 24 hours to obtain the oligomeric complex. Eighteen portions by weight were taken for later use.

[0029] Step b: Preparation of surface amino-modified titanium dioxide nanorods: Take 1 part of titanium dioxide nanorod powder and disperse it in 30 parts of anhydrous toluene. Sonicate for 30 minutes, add 3 parts of 3-aminopropyltriethoxysilane, reflux and stir at 110°C for 24 hours under nitrogen protection, centrifuge, wash three times each with toluene and ethanol, and vacuum dry at 60°C to obtain titanium dioxide nanorod powder. Take 3 parts for later use.

[0030] Step c, Compounding: 62 parts by weight of N-methyl-2-pyrrolidone were stirred and heated to 60°C at a stirring speed of 400 rpm. Then, 18 parts by weight of the oligomer complex powder, 5 parts by weight of dioctylammonium iodide, 3 parts by weight of amino-titanium dioxide nanorods, and 1.5 parts by weight of poly(ethylene-alt-maleic anhydride) were added sequentially. After each addition, the mixture was stirred at 60°C and 400 rpm for 30 minutes. After all components were added, the temperature was raised to 75°C, the stirring speed was increased to 800 rpm, and the mixture was stirred for 4 hours to form a dark, viscous liquid. The liquid was then pressure filtered through a 0.1 μm polytetrafluoroethylene membrane in a glove box. The filtrate, used as a steam-transfer mineralization aid, was stored in a brown glass bottle for later use.

[0031] This embodiment also provides a method for preparing an excited-light display film, the method comprising the following steps by weight: Step 1: Add 8 parts by weight of tetraethyl orthosilicate to 13 parts by weight of anhydrous ethanol and stir at 25°C and 300 rpm for 25 minutes. While stirring in an ice-water bath (0-5°C), add dropwise a mixture of 2 parts by weight of deionized water and 0.04 parts by weight of acetic acid over 18 minutes. Stir at 3°C ​​for 50 minutes to obtain silica sol. Remove the ice bath, restore the temperature to 25°C, and add 8 parts by weight of the vapor transport mineralization aid prepared above while stirring. Heat the mixture to 40°C and stir at 600 rpm for 3 hours to obtain a composite precursor solution.

[0032] Step 2: Place the spin-coated wet film on a precision temperature-controlled hot plate preheated to 70°C and hold for 110 seconds. Increase the temperature of the hot plate to 145°C and hold for 170 seconds. Increase the temperature to 175°C and hold for 55 seconds. This gradient heat treatment yields a pre-cured dry gel film.

[0033] Step 3: Place the pre-cured film in a sealed reaction chamber. Place a shallow dish containing 2 parts by weight of pure NMP solvent at the bottom of the reaction chamber. Set the temperature of the film area to 95°C and program the temperature to 130°C at a rate of 2°C / min for 17.5 minutes. Maintain the temperature at 130°C for 22 minutes. Control the pressure in the reaction chamber to a slightly negative pressure of 5 kPa (absolute pressure) using a fine-tuning valve. Cool down to 60°C and remove the film.

[0034] Step 4: Irradiate the thin film under ultraviolet light with a wavelength of 365 nm and an intensity of 45 mW / cm² for 5 minutes to prepare the display thin film.

[0035] Example 3 This embodiment provides a raw material for preparing a light-excited display film, which, by weight, comprises: 7 parts tetraethyl orthosilicate, 12 parts anhydrous ethanol, 2 parts deionized water, 0.03 parts acetic acid, and 7 parts vapor transport mineralization agent.

[0036] The raw materials for preparing the steam transport mineralization aid include, by weight, 70 parts N-methyl-2-pyrrolidone, 15 parts oligomeric mixed ammonium halide complex, 4 parts dioctammonium iodide, 2 parts surface amino-modified titanium dioxide nanorods, and 1 part poly(ethylene-alt-maleic anhydride).

[0037] The preparation method of the steam transport mineralization aid includes the following steps: Step a: Preparation of oligomeric mixed ammonium halide complexes: 0.8 mmol formamidinium iodide, 0.15 mmol methylamine bromide, 0.5 mmol cesium bromide, 1 mmol lead iodide, 0.1 mmol lead bromide, and 20 g N,N-dimethylformamide were added under an argon atmosphere. The mixture was stirred at 500 rpm for 12 hours at room temperature. 50 mL of anhydrous diethyl ether was added, and the mixture was stirred at 800 rpm. The mixture was allowed to stand at -20°C for 4 hours, then centrifuged at 7500 rpm for 10 minutes at 4°C. The precipitate was collected, washed three times with anhydrous diethyl ether, and dried in a vacuum oven at 40°C and <10 Pa for 24 hours to obtain the oligomeric complex. 15 portions by weight were taken for later use.

[0038] Step b: Preparation of surface amino-modified titanium dioxide nanorods: Take 1 part of titanium dioxide nanorod powder and disperse it in 30 parts of anhydrous toluene. Sonicate for 30 minutes, add 3 parts of 3-aminopropyltriethoxysilane, reflux and stir at 110°C for 24 hours under nitrogen protection, centrifuge, wash three times each with toluene and ethanol, and vacuum dry at 60°C to obtain titanium dioxide nanorod powder. Take 2 parts for later use.

[0039] Step c, Compounding: 70 parts by weight of N-methyl-2-pyrrolidone were stirred and heated to 60°C at a stirring speed of 400 rpm. Then, 15 parts by weight of the oligomer complex powder, 4 parts by weight of dioctylammonium iodide, 2 parts by weight of amino-titanium dioxide nanorods, and 1 part by weight of poly(ethylene-alt-maleic anhydride) were added sequentially. After each addition, the mixture was stirred at 60°C and 400 rpm for 30 minutes. After all components were added, the temperature was raised to 70°C, the stirring speed was increased to 800 rpm, and the mixture was stirred for 3.5 hours to form a dark, viscous liquid. The liquid was then pressure filtered through a 0.1 μm polytetrafluoroethylene membrane in a glove box. The filtrate, used as a steam-transfer mineralization aid, was stored in a brown glass bottle for later use.

[0040] This embodiment also provides a method for preparing an excited-light display film, the method comprising the following steps by weight: Step 1: Add 7 parts by weight of tetraethyl orthosilicate to 12 parts by weight of anhydrous ethanol and stir at 25°C and 300 rpm for 20 minutes. While stirring in an ice-water bath (0-5°C), add dropwise a mixture of 2 parts by weight of deionized water and 0.03 parts by weight of acetic acid over 15 minutes. Stir at 5°C for 40 minutes to obtain a silica sol. Remove the ice bath, restore the temperature to 25°C, and add 7 parts by weight of the vapor transport mineralization aid prepared above while stirring. Heat the mixture to 38°C and stir at 600 rpm for 3 hours to obtain a composite precursor solution.

[0041] Step 2: Place the spin-coated wet film on a precision temperature-controlled hot plate preheated to 65°C and hold for 100 seconds. Then, raise the temperature of the hot plate to 140°C and hold for 160 seconds. Finally, raise the temperature to 170°C and hold for 50 seconds. This gradient heat treatment yields a pre-cured dry gel film.

[0042] Step 3: Place the pre-cured film in a sealed reaction chamber. Place a shallow dish containing 2 parts by weight of pure NMP solvent at the bottom of the reaction chamber. Set the temperature of the film area to 90°C and program it to 125°C at a rate of 2.5°C / min for 14 minutes. Maintain the temperature at 125°C for 18 minutes. Control the pressure in the reaction chamber to a slightly negative pressure of 5 kPa (absolute pressure) through a fine-tuning valve. Cool down to 60°C and remove the film.

[0043] Step 4: Irradiate the thin film under ultraviolet light with a wavelength of 365 nm and an intensity of 40 mW / cm² for 5 minutes to prepare the display thin film.

[0044] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that, in the preparation of the steam transport mineralization aid, the oligomer-type mixed ammonium halide complex was not prepared and added in advance. Otherwise, the contents are the same as those in Example 1.

[0045] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 lacks dioctammonium iodide in the preparation of the steam transport mineralization aid; otherwise, it is the same as Example 1.

[0046] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 lacks amino-titanium dioxide nanorods when preparing the steam transport mineralization aid; otherwise, it is the same as Example 1.

[0047] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 lacks poly(ethylene-alt-maleic anhydride) when preparing the steam transport mineralization aid; otherwise, it is the same as Example 1.

[0048] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not perform steps a (preparation of oligomer complex) and c (ordered compounding) separately. Instead, the raw materials formamidinium iodine, methylamine bromide, cesium bromide, lead iodide, lead bromide, dioctyl ammonium iodide, amino-TiO2 nanorods and polymer are added to N-methyl-2-pyrrolidone solvent at once and stirred at 80°C and 800 rpm for 4 hours. The rest of the process is the same as in Example 1.

[0049] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that Comparative Example 6 uses unmodified titanium dioxide nanorods without 3-aminopropyltriethoxysilane surface modification when preparing the steam transport mineralization aid. All other contents are the same as in Example 1.

[0050] Performance testing The photoluminescence performance, thin film uniformity, and environmental stability were tested for the examples and comparative examples. The specific methods are as follows: Photoluminescence quantum yield (PLQY) was measured using the Hamamatsu Photonics Quantum-QY absolute PL quantum yield measurement system (C11347-11) equipped with an integrating sphere and a 450 nm laser diode as the excitation source at room temperature. Five different points were measured for each sample, and the average value was taken. Emission spectra and full width at half maximum (FWHM) were measured using an Edinburgh Instruments FS5 fluorescence spectrometer under the same 450 nm laser excitation to acquire the steady-state photoluminescence (PL) spectra of the thin films. The FWHM was calculated by fitting the main spectral peak to characterize color purity. Photoluminescence mapping (PL mapping) was performed using a self-built PL mapping system, including a 532 nm laser source, a two-dimensional motorized translation stage, and a spectrometer. Within a 2 cm × 2 cm sample area, a scan was performed with a step size of 200 μm to acquire the PL spectrum at each point. The relative standard deviation (RSD) of the PL peak intensity at all points was calculated as a uniformity index. Environmental stability testing involved placing the film samples in a constant temperature and humidity chamber (ESPEC SH-242) for accelerated aging under harsh conditions of 85°C and 85% relative humidity (85°C / 85% RH). The samples were removed at regular intervals and allowed to recover for 2 hours in a standard laboratory environment (25°C, 50% RH). The initial PL peak intensity (I) was measured, and the retention rate (I / I0 × 100%) relative to the initial intensity before aging was calculated. The results are shown in Table 1.

[0051] Table 1: Performance Test Results of Examples and Comparative Examples As shown in Table 1, the films prepared in Examples 1-3 exhibit excellent overall performance. Example 1, as the optimal solution, achieves high photoluminescence quantum yield (PLQY), a narrow emission half-width (FWHM) of 18.2 nm, high environmental stability (85°C / 85%RH, 500h), and high luminescence uniformity. Comparative Example 1 suffers from a decrease in PLQY and rapid film decomposition due to precursor disorder. The stability of Comparative Examples 2 and 4 is lower than that of Example 1, confirming the crucial role of simultaneous passivation and stress buffering in reliability. The decrease in PLQY and uniformity in Comparative Examples 3 and 6 highlights the importance of amino-modified nanorods guiding uniform crystallization. The comprehensive degradation of all properties in Comparative Example 5 demonstrates the decisive influence of the ordered compounding process on achieving molecular-level pre-assembly of functional components. These data indicate that this invention, through the synergy of specific components and processes, solves the industry problem of simultaneously achieving high efficiency, color purity, uniformity, and stability in perovskite luminescent films.

[0052] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing an excited-light display thin film, characterized in that, The method includes the following steps: S1. Preparation of steam transport mineralization aid; S2. Preparation of composite precursor solution: Tetraethyl orthosilicate is added to anhydrous ethanol and stirred. Under ice-water bath and stirring conditions, a mixture of deionized water and acetic acid is added dropwise. Low-temperature stirring is continued to obtain silica sol. The ice bath is removed, the mixture is restored to room temperature, a steam transport mineralization aid is added, the temperature is raised and stirred to obtain composite precursor solution. S3. Gradient heat treatment: After the composite precursor solution is formed into a film, it is placed on a hot plate for gradient heat treatment to obtain a pre-cured dry gel film. S4. Steam-assisted annealing: The pre-cured dry gel film is placed in a closed reaction chamber for steam-assisted annealing. The reaction chamber is provided with a saturated vapor environment of N-methyl-2-pyrrolidone solvent. The annealing process is carried out by programmed temperature rise, and the film is taken out after cooling. S5. Ultraviolet light irradiation: The film processed in step S4 is irradiated under ultraviolet light to obtain an excited light display film.

2. The method as described in claim 1, characterized in that, In step S2, the raw materials in the composite precursor solution include, by weight, 7-10 parts of tetraethyl orthosilicate, 12-15 parts of anhydrous ethanol, 2 parts of deionized water, 0.03-0.05 parts of acetic acid, and 7-8 parts of steam transport mineralization aid. The specific process of step S2 is as follows: Tetraethyl orthosilicate is added to anhydrous ethanol and stirred at 25°C and 300 rpm for 20-30 minutes; a mixture of deionized water and acetic acid is added dropwise over 15-20 minutes while stirring in an ice-water bath at 0-5°C; after the addition is complete, the mixture is stirred at 3-5°C for 40-60 minutes to obtain silica sol; the ice bath is removed, the temperature is restored to 25°C, a steam transport mineralization aid is added while stirring, the mixture is heated to 38-40°C, and stirred at 600 rpm for 3 hours to obtain a composite precursor solution.

3. The method as described in claim 1, characterized in that, Step S3 gradient heat treatment includes three stages: the first stage, holding at 65-75°C for 100-120 seconds; the second stage, holding at 140-150°C for 160-180 seconds; and the third stage, holding at 170-180°C for 50-60 seconds.

4. The method as described in claim 1, characterized in that, Step S3, gradient heat treatment, includes: holding at 70-75°C for 110-120 seconds; holding at 145-150°C for 170-180 seconds; and holding at 175-180°C for 55-60 seconds.

5. The method as described in claim 1, characterized in that, In step S4, the initial temperature of the programmed temperature rise is 90-100°C, the final temperature is 125-135°C, the heating rate is 2-2.5°C / min, and the temperature is maintained at the final temperature for 18-25 minutes; the absolute pressure in the reaction chamber is controlled at 5 kPa; the initial temperature of the programmed temperature rise is 95-100°C, the temperature is increased to 130-135°C at a rate of 2°C / min, and the temperature is maintained at the final temperature for 22-25 minutes.

6. The method as described in claim 1, characterized in that, In step S5, the wavelength of the ultraviolet light is 365nm, the irradiation time is 5 minutes, and the intensity of the ultraviolet light is 40-50 mW / cm².

7. The method as described in claim 1, characterized in that, The raw materials for preparing the steam transport mineralization aid include, by weight: 62-70 parts of N-methyl-2-pyrrolidone, 15-20 parts of oligomeric mixed ammonium halide complex, 4-7 parts of dioctyl ammonium iodide, 2-5 parts of surface amino-modified titanium dioxide nanorods, and 1-3 parts of poly(ethylene-alt-maleic anhydride).

8. The method as described in claim 1, characterized in that, The preparation method of the steam transport mineralization aid includes the following steps: S1a, Preparation of oligomeric mixed ammonium halide complex powder; S1b, Preparation of surface amino-modified titanium dioxide nanorod powder; S1c, Compounding: N-methyl-2-pyrrolidone is stirred and heated at 60°C and 400 rpm. Oligomeric mixed ammonium halide complex powder, dioctyl ammonium iodide, amino-modified titanium dioxide nanorod powder, and poly(ethylene-alt-maleic anhydride) are added. After each component is added, the mixture is stirred at 60°C and 400 rpm for 30 minutes. The temperature is raised to 70-80°C, the stirring rate is increased to 800 rpm, and the mixture is stirred for 3.5-4 hours to form a viscous liquid. After filtration, the steam transport mineralization aid is obtained.

9. The method as described in claim 8, characterized in that, The preparation of oligomeric mixed ammonium halide complex powder includes: dissolving formamidinium iodine, methylamine bromide, cesium bromide, lead iodide, and lead bromide in N,N-dimethylformamide under an argon atmosphere, stirring at 500 rpm for 12 hours at room temperature, adding anhydrous diethyl ether, stirring at 800 rpm, and allowing to stand at -20°C for 4 hours. The precipitate is collected by centrifugation, washed, and dried under vacuum conditions of 40-50°C and pressure below 10 Pa for 24 hours to obtain oligomeric mixed ammonium halide complex powder.

10. The method as described in claim 8, characterized in that, The preparation of surface amino-modified titanium dioxide nanorod powder includes: dispersing titanium dioxide nanorod powder in anhydrous toluene, sonicating for 30 minutes, adding 3-aminopropyltriethoxysilane, refluxing and stirring at 110°C for 24 hours under nitrogen protection, centrifuging, washing, and drying to obtain surface amino-modified titanium dioxide nanorod powder.

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