Perovskite quantum dot / polysiloxane hybrid vehicle-mounted backlight conversion film and preparation method thereof

Abstract

The application relates to the technical field of light conversion display materials, in particular to a perovskite quantum dot / polysiloxane hybrid vehicle-mounted backlight conversion film and a preparation method thereof. A conversion layer of the conversion film comprises a polysiloxane matrix and CsPbBr3 green light and CsPbI3 red light quantum dots dispersed in the matrix. The surface of the quantum dots is anchored by a sulfur ether sulfur and a ring nitrogen multi-point of a multi-tooth thiadiazole silane coupling agent. The 5-position mercapto group is incorporated into a sulfur ether crosslinking network through mercapto-olefin addition. The matrix is a methylphenyl polysiloxane with a phenyl molar content of 30% to 50%, and a double-network structure of a sulfur ether crosslinking network and a silicon hydrogen addition crosslinking network is formed. During preparation, free mercapto groups are removed through low-temperature mercapto-olefin addition to eliminate the poisoning of the platinum catalyst, and then main curing is carried out through high-temperature platinum catalytic addition. The color gamut coverage of the film is more than 95% of BT.2020, the light efficiency attenuation is less than 5% after aging at 85 DEG C for 1000 hours, and the film meets the vehicle requirement.

Description

Technical Field

[0001] This invention relates to the field of light conversion display materials technology, specifically to a perovskite quantum dot / polysiloxane hybrid automotive backlight conversion film and its preparation method. Background Technology

[0002] With the rapid development of smart cockpits, automotive displays are placing increasingly higher demands on color reproduction capabilities, and wide color gamut has become one of the core indicators of high-end automotive LCD backlight modules. In the backlight architecture that uses blue light-emitting diodes to excite quantum dots to achieve the conversion between green and red light, the emission half-peak width and emission wavelength of quantum dots are continuously adjustable, which can significantly widen the display color gamut. However, the automotive cabin is a typical high-temperature and high-humidity harsh environment, and the operating temperature near the dashboard is consistently high, which places much higher demands on the reliability of color conversion materials than on consumer electronics displays.

[0003] Traditional color-conversion quantum dots are mainly composed of cadmium-based chalcogenide quantum dots. The cadmium they contain is subject to strict regulations on hazardous substances, making it difficult to meet the environmental requirements for automotive-grade electronic products. In contrast, all-inorganic cesium lead halide perovskite quantum dots possess near-100% fluorescence quantum yield, a narrow emission peak, and continuously tunable emission wavelengths, with an absorption coefficient around 10. 5 cm -1 Perovskite quantum dots are considered a new generation of wide color gamut color conversion materials. However, the surface of perovskite quantum dots is wrapped with hydrophobic organic ligands, and their ionic lattice is relatively soft. The ligands and the lattice are in a dynamic adsorption-desorption equilibrium. Under the influence of water, oxygen, heat and light, the ligands are prone to desorption and the lattice is prone to destruction, resulting in fluorescence quenching and color decay. Stability issues have become the main obstacle to their application in the field of automotive displays.

[0004] To address the stability issue of perovskite quantum dots, existing technologies have proposed various encapsulation and surface modification schemes. US patent application US20200385632A1 (METHOD FOR PREPARATION OF PEROVSKITE QUANTUM DOT(PQD) / POLYMER / CERAMIC TERNARY COMPLEX) discloses a dual encapsulation strategy of first coating the quantum dots with a ceramic layer and then with a polymer. However, its objective drawbacks include interfacial thermal stress between the ceramic shell and the polymer, cumbersome preparation steps, and a thick ceramic shell that significantly increases the thickness of the color conversion layer, hindering thin-film formation and patterning.

[0005] US Patent US11802238B2 (Ligand exchange of perovskite quantum dots and solar cell devices manufactured using the same) discloses a method for solid-state ligand exchange of quantum dots using carboxylate ions. However, its technical goal is to improve the charge transport of solar cells. The ion salt ligands used do not have the ability to chemically bond with polysiloxane, and cannot solve the problem of color gamut stability of the light-emitting conversion film at high temperatures.

[0006] Regarding matrix materials, US patents US8158265B2 and US9624374B2 (Addition-curable silicone composition) disclose an addition-curable high-refractive-index silicone system composed of vinyl silicone oil, hydrogen-containing silicone oil, and platinum group catalysts. The introduction of phenyl groups enhances the refractive index of the cured product, primarily for use in LED packaging. US patent US12129412B2 (Curable silicone composition and cured product thereof) further discloses a scheme to improve dispersibility by dispersing cadmium-free quantum dots in curable silicone. However, none of these schemes acknowledge the poisoning problem of platinum catalysts by quantum dot surface ligands: existing research clearly indicates that the active ligands on the quantum dot surface poison platinum catalysts, making addition curing difficult and accompanied by severe fluorescence quenching. Sulfur-containing thiol groups are classic poisons for platinum catalysts.

[0007] A deeper problem lies in the fact that when green CsPbBr3 quantum dots and red CsPbI3 quantum dots are co-dispersed in the same matrix, the migration and exchange of halide anions occur between the two types of quantum dots. The interdiffusion of bromide and iodide ions causes a red shift in the green emission peak and a blue shift in the red emission peak, both converging towards the middle wavelength, resulting in a sharp collapse of the color gamut during high-temperature aging. Halogen vacancies are the main channels for anion migration, but the passivation ability of existing monodentate ligands is limited, making it difficult to simultaneously achieve strong anchoring, vacancy passivation, and matrix bonding.

[0008] Halogen exchange is essentially a thermally activated diffusion of halide anions in the soft-ion lattice of perovskite. Due to the low halogen vacancy formation energy of lead halide perovskites, a large number of halogen vacancies are prevalent on the surface of quantum dots. These vacancies provide low-barrier channels for the hopping migration of anions. At high temperatures, bromide and iodide ions diffuse back and forth between adjacent quantum dots via these vacancies, eventually causing the halogen compositions of the green and red quantum dots to converge, resulting in a convergence of the emission spectra towards the center. To circumvent this problem, the industry often resorts to multilayer structures with layered coatings of green and red quantum dots, or replaces red perovskite quantum dots with fluoride red phosphors. However, the former increases process complexity, while the latter sacrifices the color purity of red light. Therefore, fundamentally suppressing halogen exchange in a single-layer film blended with green and red quantum dots is one of the key challenges in achieving high color gamut automotive backlight conversion films.

[0009] Furthermore, automotive-grade electronic products have far more stringent reliability requirements for color conversion materials than consumer electronics. Materials are typically required to withstand accelerated aging tests involving continuous high temperatures and thermal cycling with extremely low levels of color coordinate drift and brightness decay. Existing perovskite quantum dot encapsulation films generally exhibit rapid fluorescence decay and large color coordinate drift under such demanding conditions, making them unsuitable for direct automotive applications.

[0010] In summary, existing technologies have not yet solved the following intertwined technical problems: First, the thiol ligands on the quantum dot surface poison the platinum catalyst, making the high-refractive-index addition-type curing matrix incompatible with the thiol ligand exchange system; second, the thiol group of the monodentate thiol ligand is both the sole anchoring group and a platinum poison that needs to be eliminated, and consuming the thiol group leads to quantum dot deanchoring, making both mutually exclusive; third, halogen exchange in the green-red quantum dot blend system leads to high-temperature color gamut collapse. This invention proposes solutions to the above-mentioned technical problems. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide a perovskite quantum dot / polysiloxane hybrid automotive backlight conversion film and its preparation method. Through molecular-level multidentate ligand design and time-sequential dual-network curing process, it solves the technical problems of mercapto ligand poisoning of platinum catalyst, the contradiction between anchoring and mercapto consumption, and the color gamut thermal collapse caused by halogen exchange of green and red quantum dots, thus achieving a balance between wide color gamut and automotive-grade high temperature resistance.

[0012] To achieve the above objectives, this invention provides a perovskite quantum dot / polysiloxane hybrid automotive backlight conversion film, comprising a base film and a conversion layer disposed on the surface of the base film. The conversion layer comprises a polysiloxane matrix and perovskite quantum dots dispersed therein. The perovskite quantum dots include CsPbBr3 green quantum dots and CsPbI3 red quantum dots, and their surfaces are anchored by a multidentate thiadiazole silane coupling agent. The multidentate thiadiazole silane coupling agent is a bifunctional molecule in which a trialkoxysilylpropyl group is linked to the 2-position of the 1,3,4-thiadiazole ring via a thioether bond, and a mercapto group is present at the 5-position. The sulfur atom of the thioether bond and the nitrogen atom of the thiadiazole ring are jointly anchored to the surface of the quantum dots, and the mercapto group at the 5-position is incorporated into the thioether crosslinking network via mercapto-olefin addition during the curing process. The polysiloxane matrix comprises methylphenyl polysiloxane with a phenyl molar content of 30% to 50%, forming a dual-network structure in which the thioether crosslinking network and the hydrosilylation crosslinking network interpenetrate each other.

[0013] The core concept of this invention lies in decoupling the anchoring function of quantum dots from the sacrificial function of thiol groups at the molecular level through a multidentate thiadiazole silane ligand: the thioether sulfur and cyclic nitrogen of the thiadiazole ring form a multidentate chelating pocket that undertakes surface anchoring and defect passivation of the quantum dots, while the free 5-position thiol group acts as a dedicated sacrificial group. During the first low-temperature curing stage, it is consumed by vinyl groups through thermally initiated thiol-ene addition, thereby clearing platinum poisoning and transforming into a node of the second crosslinking network before the platinum-catalyzed addition curing is initiated. Since the anchoring does not depend on this free thiol group, the consumption of the thiol group will not cause quantum dot deanchoring, thus fundamentally resolving the inherent contradiction that monodentate ligands cannot overcome.

[0014] The present invention also provides a method for preparing the above-mentioned conversion film, comprising three steps: ligand exchange, dispersion coating, and time-sequential dual-network curing. In the ligand exchange step, a multidentate thiadiazole silane coupling agent is anchored to the surface of quantum dots with thioether sulfur and cyclic nitrogen. In the dispersion coating step, the modified quantum dots are dispersed in a prepolymer of phenyl-containing vinyl silicone oil, hydrogen-containing silicone oil, and platinum catalyst and coated onto a base film. In the time-sequential curing step, mercapto-olefin addition is first performed at a lower temperature to remove free mercapto groups, followed by platinum-catalyzed hydrogen silanization for primary curing.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the thioether sulfur and cyclic nitrogen of the multidentate thiadiazole silane ligand provide multi-point anchoring, significantly improving the passivation effect of quantum dot surface defects and fluorescence quantum yield, and inhibiting the migration and exchange of bromide and iodide anions by filling halogen vacancies, thus greatly reducing the emission peak position drift of the green and red quantum dot blend system under high temperature aging; Second, free mercapto groups are directionally removed and transformed into thioether crosslinking points through sequential mercapto-olefin addition, which not only eliminates the poisoning of platinum catalyst and ensures sufficient addition curing, but also constructs a second crosslinking network that interpenetrates with the hydrosilylation network, improving the crosslinking density and interfacial covalent bond strength; Third, the methylphenyl polysiloxane with a phenyl molar content of 30% to 50% matches the refractive index of the quantum dots, reducing interfacial Fresnel reflection and improving light extraction efficiency and color gamut coverage. The prepared conversion film has a color gamut coverage exceeding 95% of the BT.2020 standard under blue light emitting diode excitation, and its luminous efficacy decay is less than 5% after aging at 85℃ for 1000 h, meeting automotive-grade reliability requirements. Attached Figure Description

[0016] Figure 1 The graph shows the relationship between different phenyl molar contents and the refractive index and color gamut coverage of the cured product. Figure 2 This is a comparison curve of the luminous efficacy of Example 1 and Comparative Example 1 at 85°C as a function of aging time. Figure 3 This is a comparison curve showing the shift in the emission peak positions of green and red light over aging time. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available.

[0018] Preparation example: Synthesis of the multidentate thiadiazole silane coupling agent DMCT-TMS The chemical name of the multidentate thiadiazole silane coupling agent used in this invention is 5-[(3,3-dimethoxy-2-oxa-3-silazhex-6-yl)thio]-1,3,4-thiadiazacyclopentanol-2-thiophenol, abbreviated as DMCT-TMS, and its molecular formula is C8H 16 N2O3S3Si, with a molecular weight of 312.49, is prepared by a monoselective thioetherification reaction of 2,5-dimercapto-1,3,4-thiadiazole.

[0019] The specific synthetic steps are as follows: Under nitrogen protection, 6.16 g (41.0 mmol, 1.0 equivalent) of 2,5-dimercapto-1,3,4-thiadiazole and 60 mL of anhydrous acetonitrile were added to a reaction flask. After stirring and dissolving, 5.95 g (43.1 mmol, 1.05 equivalent) of anhydrous potassium carbonate was added, and the mixture was activated at room temperature for 30 min to selectively remove a thiol molar. Subsequently, 8.32 g (41.8 mmol, 1.02 equivalent) of 3-chloropropyltrimethoxysilane was slowly added dropwise. After the addition was complete, the temperature was raised to 60 °C and the reaction was carried out for 8 h. During the reaction, the molar ratio of dimercaptothiadiazole to halosilane was controlled to be close to 1:1 to ensure that the monothioetherification product was the main product while suppressing the formation of dithioetherification byproducts. After the reaction, the generated potassium chloride solid was removed by filtration, the solvent was removed by vacuum distillation, and the residue was purified by vacuum distillation to obtain a pale yellow liquid DMCT-TMS with a yield of approximately 78%.

[0020] In this multidentate ligand molecule, the trimethoxysilyl group is used to form a Si-O-Si bond with the polysiloxane matrix via hydrolytic condensation; the thioether sulfur at the 2-position of the thiadiazole ring and the two nitrogen atoms on the ring form a multidentate chelate pocket, which is used to anchor Pb on the surface of the quantum dot. 2+ It fills halogen vacancies; the free thiol group at position 5 is retained as a sacrificial reaction site.

[0021] Examples of quantum dot fabrication: Fabrication of CsPbBr3 green and CsPbI3 red quantum dots The inorganic cesium lead halide perovskite quantum dots used in this invention are prepared by a hot-injection method. Taking CsPbBr3 green quantum dots as an example, cesium carbonate is first mixed with octadecene and oleic acid, and degassed under vacuum at 120°C for 1 h. The temperature is then raised to 150°C to completely dissolve the cesium carbonate, yielding a cesium oleate precursor. Lead bromide is dispersed in octadecene, and oleic acid and oleylamine are added. After degassed under vacuum at 120°C for 1 h, nitrogen gas is introduced and the temperature is raised to 170°C. The preheated cesium oleate precursor is then rapidly injected, and the reaction is terminated by rapid cooling in an ice-water bath after 5 s. The product is centrifuged and dispersed in toluene to obtain a CsPbBr3 green quantum dot dispersion. The preparation of CsPbI3 red quantum dots is similar to the above, except that lead iodide is used instead of lead bromide, and the reaction temperature is adjusted to 180°C to obtain a stable black-phase perovskite.

[0022] The prepared quantum dots were characterized as follows: transmission electron microscopy showed that the quantum dots were cubic in shape, uniformly dispersed, and had a concentrated particle size distribution; X-ray diffraction patterns showed that CsPbBr3 exhibited a cubic perovskite phase and CsPbI3 exhibited a black perovskite structure, with no impurity phase diffraction peaks; fluorescence spectroscopy showed that the emission peak of CsPbBr3 was located at approximately 520 nm with a half-maximum width at half-maximum of approximately 20 nm, and the emission peak of CsPbI3 was located at approximately 680 nm with a half-maximum width at half-maximum of approximately 38 nm; the absolute fluorescence quantum yield of both was greater than 90% as measured by integrating sphere. The prepared quantum dots will be used for subsequent ligand exchange and film formation.

[0023] Example 1 This embodiment prepares a perovskite quantum dot / polysiloxane hybrid automotive backlight conversion film, comprising a base film and a conversion layer disposed on the surface of the base film. The conversion layer is composed of a polysiloxane matrix and perovskite quantum dots dispersed therein. The quantum dots used are the products obtained in the aforementioned quantum dot preparation example.

[0024] The first step was ligand exchange. CsPbBr3 green quantum dots and CsPbI3 red quantum dots, both prepared by the hot-injection method, with a particle size of 6 nm and a fluorescence quantum yield of 93%, were prepared in toluene at a green to red quantum dot mass ratio of 4.5:1 to obtain a quantum dot dispersion. Under a nitrogen atmosphere and at 30°C, DMCT-TMS was added to the dispersion at 22% of the total quantum dot mass, and the mixture was magnetically stirred for 4 h. During this process, the thioether sulfur and cyclic nitrogen of the thiadiazole ring in DMCT-TMS anchored to the quantum dot surface, replacing the original oleic acid and oleylamine ligands, resulting in surface-modified quantum dots. For example, the multidentate ligand passivated surface defects and filled halogen vacancies through multi-point contact, while the 5-position thiol group remained in a free state.

[0025] The second step is dispersion coating. The modified quantum dots are dispersed at a mass fraction of 10% in a polysiloxane prepolymer. The prepolymer consists of methylphenyl vinyl silicone oil with a phenyl molar content of 40%, methyl hydrogen silicone oil, and platinum cassette catalyst. The molar ratio of the silicon-hydrogen bonds in the hydrogen silicone oil to the vinyl groups in the vinyl silicone oil is 0.90, the molar ratio of residual free mercapto groups to vinyl groups in the system is controlled at 0.10, and the amount of platinum catalyst is 10 ppm based on elemental platinum. The mixture is ultrasonically dispersed for 30 min to ensure uniform dispersion of the quantum dots, and then degassed for 20 min under a vacuum degree below 100 Pa to remove air bubbles. Subsequently, it is coated onto the surface-treated polyethylene terephthalate (PET) film surface using a blade coating method, controlling the wet film thickness to achieve a cured film thickness of 100 μm.

[0026] The third step is time-sequential dual-network curing. The coated film is first cured at 90℃ for 12 min for the first stage of curing: the free thiazole group at the 5-position of the thiadiazole ring undergoes a thermally initiated thiol-ene addition reaction with the vinyl group of methylphenyl vinyl silicone oil, generating thioether crosslinking points. Simultaneously, the free thiol group is directionally consumed, thus eliminating poisoning of the platinum catalyst before the platinum-catalyzed addition curing begins. The temperature is then raised to 135℃ and held for 45 min for the second stage of curing: under the action of the platinum catalyst, the vinyl group undergoes a hydrogenation-silanization addition reaction with the silane-hydrogen bonds of the hydrogen-containing silicone oil, forming a hydrosilylation crosslinking network. The two stages of curing allow the thioether crosslinking network 6 and the hydrosilylation crosslinking network 7 to interpenetrate, forming a dual-network structure. Quantum dots are covalently anchored within the dual network via multidentate ligands.

[0027] The conversion film obtained in this embodiment was subjected to performance testing. Under blue light emitting diode excitation, its color gamut coverage reached 96.3% of the BT.2020 standard. After aging at 85°C for 1000 h, the luminous efficacy decreased by 3.1%, the green light emission peak shifted by 0.4 nm, the red light emission peak shifted by 0.6 nm, and the curing gel rate was 98.5%.

[0028] Further characterization of the microstructure and initial optical properties of the conversion film in this embodiment was performed: Scanning electron microscopy cross-sectional observation showed that the quantum dots were uniformly dispersed in the polysiloxane matrix without obvious agglomeration, and the interface between the conversion layer and the base film was dense; Fourier transform infrared spectroscopy before curing was performed at 2550 cm⁻¹. -1 The stretching vibration absorption peak of free thiol groups was visible nearby, but this peak largely disappeared after curing, indicating that the free thiol groups were fully consumed by thiol-ene addition. No free thiol groups were detected in the cured film extract using the Elman reagent colorimetric method. The initial light conversion efficiency of the film under 450 nm blue light excitation reached 127% compared to Comparative Example 4, and the blue light reflectance at the interface between the conversion layer and the base film was as low as 0.9%, indicating that the 40% phenyl content methylphenyl polysiloxane achieved good refractive index matching with the quantum dots. These results collectively demonstrate that the conversion film of this embodiment not only possesses a wide color gamut and excellent high-temperature color stability, but also exhibits complete curing and strong quantum dot anchoring.

[0029] Example 2 The difference between this embodiment and Embodiment 1 is that the lower limit values ​​of each parameter are used.

[0030] In the ligand exchange step, the particle size of both CsPbBr3 green quantum dots and CsPbI3 red quantum dots is 4 nm, the fluorescence quantum yield is 90%, and the mass ratio of green to red light is 3:1. The multidentate thiadiazole silane coupling agent used has 2 methylene groups in the linking chain and methyl alkoxy groups R, and the amount added is 15% of the total mass of quantum dots.

[0031] In the dispersion coating step, the mass fraction of modified quantum dots is 5%, the phenyl molar content of methylphenyl vinyl silicone oil is 30%, the molar ratio of silicon hydrogen bonds to vinyl groups is 0.80, the molar ratio of residual free mercapto groups to vinyl groups is 0.05, the amount of platinum catalyst is 5 ppm based on platinum element, and the film thickness after curing is 50 μm.

[0032] In the time-curing step, the first stage of thiol-olefin addition is held at 80℃ for 5 min, and the second stage of platinum-catalyzed addition is held at 120℃ for 30 min.

[0033] The conversion film obtained in this embodiment was tested, and its color gamut coverage was 95.1% of the BT.2020 standard. After aging at 85°C for 1000 h, the luminous efficacy decay was 4.2%, the green peak shift was 0.6 nm, the red peak shift was 0.9 nm, and the curing gelation rate was 96.8%. The results show that even at the lower limits of each parameter, the conversion film still meets the automotive-grade requirements of color gamut coverage exceeding 95% and luminous efficacy decay less than 5%. However, when the residual thiol ratio is at the lower limit, the quantum dot anchoring is slightly weaker, and its decay rate is slightly higher than that of Example 1.

[0034] Example 3 The difference between this embodiment and Embodiment 1 is that the upper limit values ​​of each parameter are used.

[0035] In the ligand exchange step, the particle size of both CsPbBr3 green quantum dots and CsPbI3 red quantum dots is 8 nm, the fluorescence quantum yield is 96%, and the mass ratio of green to red light is 6:1. The multidentate thiadiazole silane coupling agent used has 4 methylene groups in the linking chain and ethyl alkoxy group R, and the amount added is 30% of the total mass of quantum dots.

[0036] In the dispersion coating step, the mass fraction of modified quantum dots is 15%, the phenyl molar content of methylphenyl vinyl silicone oil is 50%, the molar ratio of silicon hydrogen bonds to vinyl groups is 1.00, the molar ratio of residual free mercapto groups to vinyl groups is 0.15, the amount of platinum catalyst is 20 ppm based on platinum element, and the film thickness after curing is 150 μm.

[0037] In the time-curing step, the first stage of thiol-olefin addition is held at 100℃ for 20 min, and the second stage of platinum-catalyzed addition is held at 150℃ for 60 min.

[0038] The conversion film obtained in this embodiment was tested, and its color gamut coverage was 95.6% of the BT.2020 standard. After aging at 85°C for 1000 h, the luminous efficacy decayed by 2.4%, the green peak shifted by 0.3 nm, the red peak shifted by 0.5 nm, and the curing gelation rate was 99.1%. The results show that the decay rate of the conversion film is further reduced and the curing is more complete when the parameter upper limit is reached. However, although the refractive index continues to increase when the phenyl content is increased to 50%, the color gamut coverage is slightly lower than that of the 40% phenyl content in Example 1, indicating that the effect of phenyl content on color gamut is not monotonically linear.

[0039] Example 4 This embodiment provides another possible implementation of the present invention, using intermediate combinations of parameters and illustrating a double-layer coating method to demonstrate the process adaptability of the present invention.

[0040] In the ligand exchange step, the particle size of both CsPbBr3 green quantum dots and CsPbI3 red quantum dots was 5 nm, with a fluorescence quantum yield of 92% and a green to red quantum dot mass ratio of 5:1. The multidentate thiadiazole silane coupling agent used had 3 methylene groups (n) in the linking chain and methyl alkoxy groups (R), and was added at 25% of the total quantum dot mass. In the dispersion coating step, the modified quantum dots had a mass fraction of 8%, the phenyl molar content of the methylphenyl vinyl silicone oil was 35%, the molar ratio of silane-hydrogen bonds to vinyl groups was 0.85, the molar ratio of residual free mercapto groups to vinyl groups was 0.12, and the amount of platinum catalyst used was 12 ppm (based on elemental platinum).

[0041] Unlike the single-layer coating in Example 1, this example employs a double-layer coating method to improve film thickness uniformity: first, a layer of the above-mentioned mixed slurry is coated and pre-leveled, then a second layer is overlaid, so that the total film thickness after curing of the two wet films is 120 μm. In the sequential curing step, the first stage of mercapto-ene addition is held at 88℃ for 10 min, and the second stage of platinum-catalyzed addition is held at 140℃ for 50 min. The resulting conversion film has a color gamut coverage of 96.0% of the BT.2020 standard, and after aging at 85℃ for 1000 h, the light efficacy decay is 2.8%, the green light peak shift is 0.4 nm, the red light peak shift is 0.5 nm, and the curing gel rate is 98.8%. The results show that under intermediate parameter combinations and a double-layer coating process, the present invention can still stably achieve a wide color gamut and automotive-grade high-temperature resistance, verifying the process adaptability and repeatability of the technical solution of the present invention.

[0042] To verify the indispensability of the key technical features of the present invention, the following comparative examples are set up to compare with Example 1 from the perspectives of removing novel distinguishing features, removing molecular design, removing underlying timing, missing components, and parameter out-of-bounds.

[0043] Comparative Example 1 (a novel distinguishing feature without the multidentate ligand): Except for replacing the multidentate thiadiazole silane coupling agent DMCT-TMS with an equal amount of monodentate 3-mercaptopropyltrimethoxysilane, the rest was the same as in Example 1. Since the thiol group of the monodentate ligand is both the sole anchoring group and a platinum poison, the consumption of the thiol group during the time-curing thiol-ene stage leads to quantum dot deanchoring, and the incompletely consumed thiol group still poisons the platinum catalyst. The resulting film had a curing gelation rate of only 71.2%, a color gamut coverage reduced to 92.5%, and a light efficiency degradation of up to 18.7% after aging at 85°C for 1000 h, with a green peak shift of 3.8 nm and a red peak shift of 5.2 nm.

[0044] Comparative Example 2 (Ligand Exchange Without Molecular Design): Without ligand exchange, quantum dots with the original oleic acid and oleylamine ligands were directly dispersed in the polysiloxane prepolymer of Example 1 and cured. Because the oleic acid and oleylamine ligands do not bond to the matrix and oleylamine also poisons the platinum catalyst, the quantum dots severely aggregated and cured incompletely, with a curing gel rate of 63.5%, a color gamut coverage of 88.3%, a light efficiency attenuation of 31.5%, a green peak shift of 5.6 nm, and a red peak shift of 7.9 nm.

[0045] Comparative Example 3 (Removal of the Underlying Layer and Sequential Curing): The first stage of thiol-ene addition was omitted, and the coated film was directly placed at 135°C for 45 min for further curing. The rest was the same as in Example 1. Since the free thiol groups were not removed before the addition curing, they directly entered the platinum catalytic system to poison the catalyst and quench the quantum dots. The curing gel rate was 68.0%, the color gamut coverage was 90.1%, and the light efficiency attenuation was 22.4%.

[0046] Comparative Example 4 (component missing, phenyl removed): Phenylmethyl vinyl silicone oil was replaced with dimethyl vinyl silicone oil without phenyl, i.e., the phenyl molar content was 0, and the rest was the same as in Example 1. Due to the mismatch between the matrix refractive index and the quantum dots, the reflection loss of blue light at the interface increased, the light extraction efficiency decreased, and the color gamut coverage was 89.6%. Since the curing system and ligand design remained unchanged, its light efficiency attenuation was 9.8%, which was significantly better than that of Comparative Examples 1 to 3, further confirming that the role of phenyl is mainly reflected in light extraction and color gamut rather than stability.

[0047] Comparative Example 5 (parameter out of bounds): The molar ratio of residual free thiol to vinyl groups was increased to 0.30, exceeding the 0.05 to 0.15 range defined in this invention; otherwise, it was the same as in Example 1. Excess free thiol groups could not be completely consumed in the thiol-ene stage, and the residual thiol groups poisoned the platinum catalyst, reducing the curing gel rate to 74.5% and the light efficiency to 15.3%.

[0048] Comparative Example 6 (Halogen Removal Management Validation): A monodentate 3-mercaptopropyltrimethoxysilane ligand was used, and green and red quantum dots were blended together. The rest of the process was the same as in Example 1, to investigate halogen exchange separately. Because the monodentate ligand could not effectively fill halogen vacancies, significant bromine-iodine exchange occurred between the green and red quantum dots. After aging for 1000 h, the green peak shifted by 4.5 nm, the red peak shifted by 6.1 nm, and the color gamut coverage was 90.8%.

[0049] Color gamut coverage test: The conversion film is placed between the blue light-emitting diode backlight and the diffuser plate to assemble a backlight module. The spectral power distribution of the emitted white light is measured using a spectroradiometer. The color gamut coverage is calculated according to the International Telecommunication Union BT.2020 standard. The result is expressed as a percentage of the area of ​​the BT.2020 color gamut triangle.

[0050] High-temperature aging test: The conversion film sample was placed in an 85℃ constant temperature oven and aged for 1000 h under continuous blue light irradiation. Every 100 h, the sample was taken out and its luminous efficacy under standard excitation conditions was measured. The percentage decrease in luminous efficacy after aging relative to the initial luminous efficacy was used to characterize the luminous efficacy decay.

[0051] Emission peak shift test: The center wavelengths of the green and red emission peaks were measured before and after aging using a fluorescence spectrometer. The absolute value of the difference between the center wavelengths of the peaks before and after aging was taken as the peak shift. The smaller the peak shift, the better the halogen exchange inhibition effect.

[0052] Curing gel rate test: After accurately weighing the cured film, it was immersed in toluene at room temperature for 48 h to extract the uncrosslinked components. After being taken out, it was dried in a vacuum oven to constant weight. The percentage of the mass after extraction and drying to the mass before extraction was taken as the curing gel rate. The higher the gel rate, the more complete the crosslinking and the lower the degree of platinum poisoning.

[0053] Fluorescence quantum yield test: The absolute fluorescence quantum yield of quantum dot dispersions or films was measured using an integrating sphere fluorescence spectrometer under 450 nm blue light excitation.

[0054] Refractive index test: The refractive index of the polysiloxane cured material was measured using an Abbe refractometer at a sodium light wavelength of 589 nm and a temperature of 25°C.

[0055] Detection of residual free thiol groups: The free thiol groups in the cured membrane extract were quantified using the Elman reagent colorimetric method to determine whether the thiol groups were completely consumed by the addition of thiol-ene.

[0056] Microstructure and crystal phase characterization: The morphology and particle size distribution of quantum dots were observed using transmission electron microscopy, the crystal phase of quantum dots was analyzed by copper target radiation using X-ray diffraction, and the cross-section of the conversion film was observed using scanning electron microscopy to evaluate the dispersion state and interfacial bonding of quantum dots in the matrix.

[0057] Interfacial reflectivity and light extraction efficiency characterization: After the conversion layer was coated on the base film, the interfacial reflectivity in the blue light band was measured using a UV-Vis spectrophotometer with an integrating sphere. The emitted light flux under blue light excitation was compared with that of a control sample without phenyl under the same quantum dot load to characterize the relative light extraction efficiency.

[0058] Ligand bonding characterization: Fourier transform infrared spectroscopy was used to scan the film before and after curing, with a focus on the 2550 cm⁻¹ region. -1 Changes in the absorption peak of the stretching vibration of nearby free thiol groups can be used to determine the extent of thiol-alkene addition; the disappearance of the free thiol peak indicates that the thiol group has been converted into a thioether bond.

[0059] The key performance of Examples 1 to 3 and Comparative Examples 1 to 6 is summarized in Table 1.1, as shown in Table 1.1.

[0060] Table 1.1 Performance Comparison of Examples and Comparative Examples As shown in Table 1.1, there is a precipitous performance difference between the embodiments of the present invention and the comparative examples. Moreover, this difference is not a simple linear superposition of the features, but exhibits a significant nonlinear synergistic effect. The luminous efficacy attenuation of Examples 1 to 3 is between 2.4% and 4.2%, and the peak position shift does not exceed 0.9 nm, while the luminous efficacy attenuation of all comparative examples is significantly worse.

[0061] Comparing Comparative Example 1 with Example 1, it can be seen that simply replacing the multidentate thiadiazole silane ligand with a monodentate mercaptosilane caused a sharp increase in photoluminescence efficiency from 3.1% to 18.7%, and a sharp drop in curing gelation rate from 98.5% to 71.2%, with the green and red peak shifts amplified by approximately 9 times and 8 times, respectively. This dramatic change confirms that the anchoring-mercapto-decoupling design of the multidentate ligand is the decisive factor in performance: the monodentate ligand simultaneously de-anchors when consuming mercapto groups, leading to the failure of both surface passivation and platinum-catalyzed curing, with the degradation of both being superimposed and amplified.

[0062] A horizontal comparison of the gradient data from Examples 1 to 3 reveals that, although the three examples use the lower limit, median, and upper limit of the parameters respectively, their luminous efficacy attenuation is consistently within a narrow range of 2.4% to 4.2%, and their color gamut coverage exceeds 95%. This indicates that the parameter range defined by the present invention can reliably achieve the expected effect throughout the entire range, demonstrating good process tolerance. In Example 3, when the upper limit of the parameters is used, the amount of multidentate ligand, the proportion of residual thiol, and the curing temperature and time are all at relatively high levels, resulting in stronger quantum dot anchoring and more complete cross-linking, thus leading to the lowest luminous efficacy attenuation and the highest curing gel rate. In Example 2, when the lower limit of the parameters is used, the proportion of residual thiol is at the lower limit of 0.05, resulting in relatively fewer thiol groups available for anchoring and cross-linking, and a slightly lower quantum dot anchoring rate. Therefore, its luminous efficacy attenuation is relatively the highest among the three examples, but it is still better than the 5% automotive-grade limit. This gradient pattern corroborates the window effect revealed in Table 1.3, indicating that a higher residual thiol ratio within the window is beneficial for improving anchoring and stability, but once it exceeds the limit, it deteriorates rapidly due to poisoning of the platinum catalyst.

[0063] Comparing Comparative Example 3 with Example 1, it can be seen that by simply eliminating the first stage of time-curing (thiol-ene stage) and using one-step curing, the light efficiency attenuation increased to 22.4% and the gelation rate decreased to 68.0%, indicating that time separation is a necessary condition for removing platinum poisoning and ensuring complete curing. Comparative Example 5 further shows that when the residual thiol to vinyl molar ratio exceeds 0.30, the excess thiol cannot be completely consumed and poisons the platinum catalyst, resulting in a simultaneous deterioration in both the gelation rate and attenuation rate. This defines a stoichiometric window of 0.05 to 0.15.

[0064] Comparative Example 4 reveals the unique role of phenyl groups: removing phenyl groups reduces the gamut coverage to 89.6%, but the luminous efficacy decreases by only 9.8%, significantly better than Comparative Examples 1 to 3. This indicates that the contribution of phenyl groups is concentrated in light extraction and gamut enhancement brought about by refractive index matching, while stability is mainly guaranteed by the multidentate ligands and the temporal dual network. These two types of features act on different dimensions and are not interchangeable. Combined with the phenomenon in Example 3 where the gamut slightly decreased when the phenyl content increased to 50% compared to 40%, it can be seen that the effect of phenyl content on the gamut is a non-linear relationship of initial increase followed by a slowdown.

[0065] The suppression effect of halogen exchange can be directly reflected by the shift in emission peak position over aging time. For example... Figure 2 As shown, the luminous efficacy of Example 1 decreased only slowly within 1000 hours of aging at 85°C, while the luminous efficacy of Comparative Example 1 decreased rapidly, and the two curves showed a clear divergence; Figure 3As shown, the green and red emission peaks of Example 1 remained relatively stable throughout the aging process, with peak shifts of only 0.4 nm and 0.6 nm, respectively. In contrast, Comparative Example 6, which used a monodentate ligand and blended green and red quantum dots, showed a gradual red shift in the green peak and a gradual blue shift in the red peak with aging, both converging towards the middle wavelength, with peak shifts of 4.5 nm and 6.1 nm, respectively. This comparison directly demonstrates that the multidentate thiadiazole silane ligand effectively increases the activation energy of halide anion migration by filling halide vacancies, kinetically suppressing bromine-iodine exchange between green and red quantum dots, thereby maintaining color coordinate stability at long-term high temperatures. In summary, this invention, through the synergy of multidentate ligand design, temporal dual-network curing, and phenyl refractive index matching, simultaneously achieves high color gamut, low attenuation, and color coordinate stability in a single-layer blend film. These three aspects support each other rather than simply superimposing, demonstrating a significant nonlinear synergistic effect.

[0066] The effects of phenyl molar content on refractive index, interface reflection and color gamut were further investigated, and the results are listed in Table 1.2.

[0067] Table 1.2 Effect of phenyl molar content on optical properties From Table 1.2 and in combination Figure 1 As the phenyl molar content increases from 0 to 40%, the refractive index of the cured material increases from 1.41 to 1.54, tending to match the refractive index of the quantum dots. The Fresnel reflectance of blue light at the interface between the conversion layer and the base film decreases from 4.1% to 0.9%, the relative light extraction efficiency increases to 127%, and the color gamut coverage increases from 89.6% to 96.3%. However, when the phenyl content further increases to 50%, although the refractive index continues to rise to 1.58 and the light extraction efficiency increases to 131%, the color gamut coverage actually drops back to 95.6%. This is because the excessively high phenyl content exacerbates phase separation and haze within the matrix, and the scattering loss offsets the gain from refractive index matching. Therefore, a preferred range for the phenyl molar content is established between 30% and 50%, with 40% being the optimal value, reflecting the nonlinear influence of this parameter on the color gamut.

[0068] To reveal the effect of the residual mercapto to vinyl molar ratio on quantum dot anchoring and curing, the window effect of this ratio was further investigated, and the results are listed in Table 1.3.

[0069] Table 1.3 Window effect of residual thiol to vinyl molar ratio Table 1.3 reveals a significant window effect in the molar ratio of residual thiol groups to vinyl groups. When this ratio is too low, as low as 0.02, there are insufficient thiol groups available for anchoring and crosslinking, resulting in a quantum dot anchoring rate of only 78%. Although the curing gelation rate is high, quantum dot deanchoring leads to a light efficiency degradation of 8.5%. When the ratio is within the window of 0.05 to 0.15, the quantum dot anchoring rate reaches 91% to 97%, the light efficiency degradation decreases to 2.4% to 4.2%, and the curing gelation rate remains above 96.8%, with no or only trace amounts of residual free thiol groups detected. When the ratio exceeds the limit and rises to 0.30, the excess free thiol groups cannot be completely consumed in the thiol-olefin stage, and the significantly detected residual thiol groups poison the platinum catalyst, causing the curing gelation rate to plummet to 74.5% and the light efficiency degradation to rise to 15.3%. This window effect indicates that the amount of thiol groups must be balanced between sufficient anchoring and crosslinking and non-poisoning of the platinum catalyst, which is the basis for limiting the molar ratio to 0.05 to 0.15 in this invention.

[0070] The superior performance of this invention stems from the synergistic effect of multidentate ligand design, sequential dual-network curing, and phenyl refractive index matching in different dimensions, and there is a causal and progressive relationship among the three: the anchoring of multidentate ligands and decoupling of thiol groups is the underlying cause, the transformation of poison into benefit by the sequential dual network is the direct result, and phenyl refractive index matching provides independent gains in the optical dimension.

[0071] This causal progression determines that the three types of features are neither substituted for each other nor can be omitted. The anchoring-thiol decoupling design of the multidentate ligand is at the bottom of the causal chain. It is both the physical basis for surface defect passivation and halogen vacancy filling, and the prerequisite for the sacrificial consumption of free thiol groups without the quantum dots detaching. It is precisely because of this bottom-level design that the transformation of poisoning into benefit through the temporal dual network can be achieved. Otherwise, as shown in Comparative Example 1, the monodentate ligand would simultaneously detach when consuming thiol groups, and temporal curing would be impossible. The temporal dual network curing is a direct result of the bottom-level design. It transforms the free thiol groups that should poison the platinum catalyst into nodes of the second cross-linked network, so that the quantum dots are covalently locked by the dual network. The phenyl refractive index matching acts on the optical extraction dimension, which is independent of the stability dimension. As shown in Comparative Example 4, removing the phenyl group only affects the color gamut and does not significantly affect the stability. The three functions each perform their own roles and support each other, together constituting the complete technical logic of this invention that combines wide color gamut and high stability under automotive-grade high-temperature conditions.

[0072] From the perspective of the anchoring mechanism, the multidentate thiadiazole silane ligand, with its multidentate pocket consisting of the thioether sulfur of the thiadiazole ring and two ring nitrogen atoms, interacts with the undercoordinated Pb on the quantum dot surface. 2+Multidentate coordination is formed. Compared with the weak single-point coordination of monodentate thiol groups, the total bonding energy of multidentate coordination is significantly improved, and the ligands are less prone to desorption at high temperatures, thus maintaining the continuous passivation of surface defects. At the same time, the nitrogen and sulfur electron-donating atoms in the multidentate pockets fill the halogen vacancies. Since halogen vacancies are the main channels for anion migration, the filling of vacancies directly increases the activation energy of ion migration, kinetically inhibiting the exchange of bromide and iodide anions between green and red quantum dots. This is the fundamental reason why the peak position drift of the examples in Table 1.1 is much smaller than that of the comparative examples.

[0073] From the perspective of the solidification mechanism, the free thiol groups are decoupled from the quantum dot anchoring function at the molecular level. This allows the free thiol groups to be completely consumed by the thiol-ene addition in the first low-temperature stage without causing quantum dot deanchoring. The removal of free thiol groups eliminates the poisoning of the platinum catalyst, ensuring the full progress of the second-stage platinum-catalyzed hydrosilylation. Simultaneously, the thioether bonds generated by the thiol-ene addition form a second cross-linking network, which interpenetrates with the hydrosilylation network to form a dual-network structure. This dual-network structure increases the cross-linking density and glass transition temperature of the matrix, and covalently locks the quantum dots within the network through the thioether bonds, thereby inhibiting quantum dot migration, aggregation, and ligand desorption at a high temperature of 85°C. This is the fundamental reason why the light efficiency attenuation in the example is less than 5%.

[0074] The advantages of multidentate ligands can be further explained from the perspective of anchoring energy. Monodentate mercaptosilanes coordinate with the quantum dot surface through only one Pb-S bond, and their coordination is a weak single-point interaction, which is prone to desorption under high-temperature thermal disturbances. In contrast, the multidentate thiadiazole silane ligand of this invention forms a three-point coordination with two cyclic nitrogen atoms through thioether sulfur. The synergy of multiple coordination bonds makes the total anchoring energy significantly higher than the sum of single-point coordination, and the chelation effect brings an additional entropy increase stabilization contribution, enabling the ligand to form a stable chelate ring on the quantum dot surface. Even if the free mercapto group, which is the sacrificial group, is consumed in the mercapto-ene stage, the chelate anchor point formed by thioether sulfur and cyclic nitrogen still firmly fixes the ligand to the quantum dot surface. This is fundamentally different from the behavior of monodentate ligands, which consume mercapto groups and thus de-anchor, and also explains the reason for the precipitous performance drop after Comparative Example 1 in Table 1.1 was replaced with a monodentate ligand.

[0075] The selection of the number of methylene groups n and the alkoxy group R in formula (I) of this invention also affects the performance. The length n of the connecting chain determines the flexible spacing between the trimethoxysilyl group and the thiadiazole anchor head. If n is too small, steric hindrance makes it difficult for the trimethoxysilyl group to fully participate in matrix condensation. If n is too large, it increases the degree of freedom of the chain segment and weakens the positioning of the anchor head. Therefore, n is preferably 3 to balance matrix bonding and anchor positioning. The type of alkoxy group R affects the hydrolysis condensation rate. The hydrolysis activity of methoxy is higher than that of ethoxy. Methyl is preferred to ensure that the trimethoxysilyl group is quickly incorporated into the polysiloxane network. The above structural parameters, together with the process parameters such as dosage and curing conditions, constitute the complete technical solution of this invention.

[0076] To further clarify the chemical nature of this invention, the following is an in-depth analysis of the three key chemical reactions involved and their interrelationships.

[0077] Firstly, the thermodynamic basis of ligand exchange. The CsPbBr3 and CsPbI3 quantum dot surfaces use oleate and oleylamine as initial ligands, which interact with surface Pb... 2+ The coordination between them is a monodentate carboxylate or amine, the bond is weak and in dynamic adsorption-desorption equilibrium. When the polydentate thiadiazole silane ligand DMcT-TMS is introduced, the soft basic sulfur donor and the thiadiazole cyclic nitrogen pair with the soft acidic Pb... 2+ Exhibiting stronger affinity, according to the hard and soft acid-base theory, the formation of Pb-S bonds is thermodynamically more favorable than that of Pb-O bonds. The multidentate chelation effect further enhances the coordination stability constant through entropy increase, directing ligand exchange towards the formation of surface-modified quantum dots. The chelate ring formed by multidentate coordination locks the ligand onto the quantum dot surface. Even if the free thiol groups are subsequently consumed, the chelate anchor points formed by the thioether sulfur and the cyclic nitrogen still prevent the ligand from detaching. This is the chemical basis that distinguishes this invention from monodentate ligands.

[0078] Secondly, the free radical mechanism of thiol-ene addition. In the first curing stage (80°C to 100°C), free thiol groups in the system are thermally activated to generate sulfur radicals. These sulfur radicals undergo anti-Markovnikov addition to the vinyl double bonds of vinyl silicone oil, generating carbon radicals. The carbon radicals then abstract hydrogen atoms from another thiol group to generate new sulfur radicals and complete chain transfer, thus perpetuating the cycle. Because thiol-ene addition is insensitive to oxygen and occurs relatively quickly, it can selectively proceed at low temperatures. However, platinum-catalyzed hydrosilylation has a lower rate in this temperature range. Therefore, by controlling the timing of temperature changes, thiol-ene addition can be prioritized over platinum-catalyzed addition, ensuring that free thiol groups are eliminated before the platinum catalyst participates in the reaction in large quantities. The resulting thioether bonds have high thermal stability, forming a robust thioether crosslinking network.

[0079] Thirdly, the metal complex mechanism of platinum-catalyzed hydrogen silanization. In the second stage of curing at 120°C to 150°C, the platinum catalyst activates the Si-H bonds of the hydrogen-containing silicone oil. According to the Chuck-Harrod mechanism, the vinyl group first coordinates to the platinum center, and then the Si-H groups insert into and reduce the coordinate double bonds to generate Si-CH2-CH2-Si linkages, forming a hydrosilylation cross-linking network. It is worth noting that the sulfur atom in the thiol group has a strong coordinating ability and can form a stable Pt-S bond with the platinum center, occupying the catalytic active site and causing catalyst poisoning and deactivation. This is the chemical root cause of the incompatibility between quantum dot thiol ligands and platinum catalytic addition systems in existing technologies. This invention, through the aforementioned timing design, converts the free thiol group into a platinum-inert thioether before this stage. The coordinating ability of thioether sulfur is much weaker than that of thiol sulfur, thereby eliminating the poisoning of the platinum catalyst.

[0080] In summary, this invention transforms the traditional poison of thiol groups (hydrosilaneized compounds) into a beneficial component for constructing a second cross-linked network through multidentate decoupling design at the molecular level and sequential temperature control at the process level, thus turning a poison into a benefit. Simultaneously, the strong anchoring and halogen vacancy passivation brought about by multidentate coordination inhibit ligand desorption and halogen exchange at high temperatures. The orderly sequence of these three types of reactions in time and space ensures the stability of the color gamut and the maintenance of luminous efficacy of the conversion film under automotive-grade high-temperature conditions.

[0081] Further analysis from the perspective of dual-network synergy reveals that the sulfide crosslinking network and the hydrosilylation crosslinking network are independent in chemical composition and crosslinking mechanism, yet they interpenetrate to form an interpenetrating network structure. The sulfide crosslinking network, connected by flexible sulfide bonds, imparts a certain toughness to the matrix to buffer interfacial stress caused by differences in thermal expansion coefficients at high temperatures. The hydrosilylation crosslinking network, composed of rigid silicon-carbon bonds, provides a higher crosslinking density and glass transition temperature. This combination of rigidity and flexibility ensures that the cured material at 85°C neither becomes too soft, leading to quantum dot migration and aggregation, nor too brittle, resulting in microcracks, thus maintaining the structural integrity and optical uniformity of the conversion layer. Simultaneously, the quantum dots are covalently bonded to the interpenetrating network via a dual pathway of trimethoxysilyl groups of multidentate ligands and sulfide sulfur, effectively fixing the quantum dots point by point, further suppressing their displacement and collisions under thermal motion. This is the microstructural basis for the significantly lower light efficiency attenuation compared to the comparative examples in this invention.

[0082] From an automotive-grade reliability perspective, the operating environment temperature of automotive displays is consistently higher than that of consumer electronics, and the thermal shock from start-stop cycles places stringent demands on the thermal stability and interfacial bonding of color conversion materials. The conversion film obtained in this invention, under accelerated aging conditions of continuous blue light irradiation at 85°C, exhibits a light efficiency attenuation of less than 5% and a green and red emission peak shift of no more than 0.9 nm after 1000 hours, indicating that its color coordinates remain stable under long-term high-temperature conditions, meeting the requirements for color consistency and lifespan in automotive-grade displays. Furthermore, the all-inorganic perovskite quantum dots used in this invention are cadmium-free, complying with the restrictions on hazardous substances in automotive-grade electronic products. Its preparation process employs conventional ligand exchange, coating, and segmented thermosetting, making it compatible with existing roll-to-roll coating production lines and feasible for large-scale production.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite quantum dot / polysiloxane hybrid automotive backlight conversion film, characterized in that, The system includes a base film and a conversion layer disposed on the surface of the base film. The conversion layer comprises a polysiloxane matrix and perovskite quantum dots dispersed in the polysiloxane matrix. The perovskite quantum dots include CsPbBr3 green quantum dots and CsPbI3 red quantum dots. The surface of the perovskite quantum dots is anchored by a multidentate thiadiazole silane coupling agent. The multidentate thiadiazole silane coupling agent is shown in formula (I). Formula (I) In formula (I), the 2-position of the 1,3,4-thiadiazole ring is connected by a thioether bond —(CH2). n —Si(OR)3 group, n is an integer from 2 to 4, R is methyl or ethyl, the sulfur atom of the thioether bond and the nitrogen atom of the 1,3,4-thiadiazole ring are anchored together on the surface of the perovskite quantum dot; the polysiloxane material includes methylphenyl polysiloxane with a phenyl molar content of 30% to 50%; the polysiloxane material has a dual network structure, the dual network structure includes a thioether crosslinking network and a hydrosilylation crosslinking network, and the 5-position of the 1,3,4-thiadiazole ring is incorporated into the thioether crosslinking network via a thioether bond.

2. The conversion membrane according to claim 1, characterized in that, In formula (I), n is 3, R is methyl, and the amount of the multidentate thiadiazole silane coupling agent is 15% to 30% of the mass of the perovskite quantum dots.

3. The conversion membrane according to claim 1, characterized in that, The molar ratio of residual thiol groups to vinyl groups in the polysiloxane matrix is ​​0.05 to 0.

15.

4. The conversion membrane according to claim 1, characterized in that, The platinum content in the conversion layer is 5 ppm to 20 ppm.

5. The conversion membrane according to claim 1, characterized in that, The particle size of the CsPbBr3 green quantum dots and the CsPbI3 red quantum dots are both 4 nm to 8 nm, and the fluorescence quantum yield is greater than 90%.

6. The conversion membrane according to claim 1, characterized in that, The mass ratio of the CsPbBr3 green quantum dots to the CsPbI3 red quantum dots is 3:1 to 6:

1.

7. The conversion membrane according to claim 1, characterized in that, The thioether crosslinking network and the hydrosilylation crosslinking network interpenetrate to form an interpenetrating network structure, and the perovskite quantum dots are covalently bonded to the interpenetrating network structure by the multidentate thiadiazole silane coupling agent.

8. The method for preparing the conversion membrane according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1, the perovskite quantum dots are mixed with the multidentate thiadiazole silane coupling agent, so that the sulfur atoms of the thioether bonds and the nitrogen atoms of the 1,3,4-thiadiazole rings are anchored on the surface of the perovskite quantum dots to obtain modified quantum dots; S2, the modified quantum dots are dispersed in a polysiloxane prepolymer at a mass fraction of 5% to 15%, the polysiloxane prepolymer comprising methylphenyl vinyl silicone oil with a phenyl molar content of 30% to 50%, hydrogen-containing silicone oil, and a platinum catalyst, wherein the molar ratio of the silane-hydrogen bonds of the hydrogen-containing silicone oil to the vinyl groups of the methylphenyl vinyl silicone oil is 0.8 to 1.0, and after dispersion and degassing, the mixture is coated onto the surface of a base film with a coating thickness of 50 μm to 150 μm. μm; S3, firstly, at 80℃ to 100℃, the thiol group at the 5-position of the 1,3,4-thiadiazole ring undergoes a thiol-ene addition reaction with the vinyl group to generate a thioether crosslinking point, and then the temperature is raised to 120℃ to 150℃, and the vinyl group undergoes an addition reaction with the silane-hydrogen bond catalyzed by the platinum catalyst, and the mixture is cured for 30 min to 60 min to obtain the conversion film.

9. The preparation method according to claim 8, characterized in that, Step S1 is carried out in an inert atmosphere at room temperature to 40°C, wherein the trialkoxysilyl group of the multidentate thiadiazole silane coupling agent is hydrolyzed and condensed into the polysiloxane matrix.

10. The preparation method according to claim 8, characterized in that, In step S3, the temperature is maintained at 80°C to 100°C for 5 min to 20 min to deplete the free thiol groups before the temperature is raised to 120°C to 150°C.

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