Room temperature synthesis and application of perovskite quantum dots and polymorphous luminescent products based on ionic cyclodextrin ligands

Abstract

The application belongs to the technical field of advanced photoelectric materials, and particularly relates to a room-temperature synthesis and application of a perovskite quantum dot and a multi-form light-emitting product based on an ionic cyclodextrin ligand. The application provides a strategy for room-temperature synthesis of a perovskite quantum dot assisted by an ionic cyclodextrin. In the method, a lead halide salt (PbX2) and an ionic cyclodextrin ligand are dissolved in a polar solvent at room temperature to prepare a stable precursor solution; then, a cesium oleate solution is injected into the system, and a perovskite quantum dot is prepared after reaction. The obtained quantum dot is dispersed in a non-polar solvent to further prepare a quantum dot light-emitting solution with high light-emitting performance. Based on the quantum dot solution, various derivative multifunctional products can be further prepared. The application scheme has the advantages of mild reaction conditions, simple preparation steps, excellent product performance and easy scale-up, and lays a solid foundation for the practical application of perovskite quantum dots.

Description

Technical Field

[0001] This invention belongs to the field of advanced optoelectronic materials technology, specifically relating to the room-temperature synthesis and application of perovskite quantum dots and multi-morphological luminescent products based on ionic cyclodextrin ligands. Background Technology

[0002] Perovskite quantum dots, especially all-inorganic perovskite quantum dots (CsPbX3, X = Cl) - , Br - , I - With its excellent photoluminescence quantum yield (PLQY), narrow emission half-width, continuously tunable emission wavelength, and high color purity, perovskite has shown great application potential in next-generation optoelectronic materials, display technologies, solid-state lighting, lasers, and photodetectors. Furthermore, perovskite's solution processability lays the foundation for fabricating low-cost, large-area flexible optoelectronic devices and provides a feasible pathway.

[0003] Currently, the mainstream method for preparing high-performance perovskite quantum dots in the laboratory is the high-temperature hot-injection method, which requires an inert gas atmosphere such as nitrogen or argon. This method typically involves rapidly injecting a cesium precursor at high temperatures (usually 120-180°C) into a vigorously stirred lead halide precursor solution under nitrogen protection. Precise control of nucleation and growth kinetics is crucial to obtaining quantum dots with uniform size and excellent luminescence. However, this method has inherent drawbacks in large-scale production: firstly, the high-temperature process consumes a lot of energy, and the reaction is extremely sensitive to temperature, injection rate, and stirring conditions, resulting in a narrow process window; secondly, the complex and stringent reaction conditions make it difficult to directly scale up the method, leading to high costs for large-scale production; and thirdly, this method relies on high temperatures to improve the fluidity of traditional long-chain organic ligands such as oleic acid and oleylamine, ensuring their full dispersion in the reaction system, thereby improving the solubility and dispersibility of the precursor.

[0004] More importantly, even if high-quality quantum dot solutions are obtained using the methods described above, these solutions still face severe performance degradation during subsequent application-oriented processing. This problem stems from the fact that traditional ligands are highly susceptible to dissociation and loss due to solvent exchange, phase interface changes, or heat treatment. This leads to damage to the ligand layer of the quantum dot solution during purification, drying, matrix recombination, and film formation, exposing numerous surface defects (such as halogen vacancies and uncoordinated lead sites). These surface defects become non-radiative recombination centers, ultimately resulting in the luminescent performance of the solid-state product being far lower than that of the initial solution state. This performance degradation severely restricts the full realization of the properties of perovskite quantum dot materials and the effective release of their material efficiency.

[0005] This challenge is particularly prominent in pure red-luminescent perovskite quantum dots (such as CsPbI3). The luminescent active phase (cubic α phase) of CsPbI3 is thermodynamically metastable at room temperature and readily transforms into the non-luminescent orthorhombic phase (δ phase). Furthermore, its lattice is highly sensitive to halogen composition, quantum size, and surface states. While emerging room-temperature synthesis methods (such as ligand-assisted reprecipitation) have achieved success in green-luminescent systems, it remains difficult to simultaneously achieve high phase purity, high luminescent efficiency, and high stability in red-luminescent systems. Current strategies for improving red-luminescent stability, such as tin (Sn) alloying and heterostructure construction, mostly focus on bulk material modification or post-processing modification, and have not yet fundamentally solved a systemic problem—that is, achieving efficient synthesis, intrinsic stability, and lossless transfer of luminescent properties during processing under mild, scalable synthesis conditions.

[0006] Therefore, there is an urgent need in this field to develop novel synthesis and materials systems that meet the following requirements: controllable and efficient synthesis of high-performance perovskite quantum dots (especially red quantum dots, which are more difficult to prepare) under mild and simple conditions at room temperature; the ability to fundamentally solve the performance degradation problem of quantum dots in subsequent processing steps such as purification, drying, and film formation, achieving high performance retention from solution to solid-state luminescent materials; and excellent process compatibility and scalability, enabling the direct and flexible preparation of various end-use materials such as inks, powders, and thin films. Such technologies will connect the entire chain of perovskite quantum dot synthesis from laboratory to practical product applications, possessing significant industrial application value. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention provides a perovskite quantum dot based on an ionic cyclodextrin ligand. This quantum dot can be used for the room-temperature synthesis of various luminescent products, including the room-temperature synthesis of high-luminescence quantum dot luminescent solutions, solid fluorescent powders, and large-area transparent luminescent films, which has important application prospects.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a room-temperature synthesis method for perovskite quantum dots based on ionic cyclodextrin ligands, the method comprising the following steps: S11. Dissolve lead halide salt PbX2, 9-octadecenylhalogenated amine OAmX, and ionic cyclodextrin in a polar solvent to obtain a lead halide precursor solution; wherein X is selected from Cl - , Br - or I - At least one of the following; the ionic cyclodextrin includes cationic cyclodextrin, anionic cyclodextrin, and zwitterionic cyclodextrin; In the method of this invention, the contribution of ionic cyclodextrin to perovskite quantum dots is mainly reflected in two aspects: firstly, as a dispersant, it improves the solubility of the precursor, effectively enhancing the uniformity of the precursor and ensuring uniform nucleation during the synthesis stage; secondly, it precisely controls crystal nucleation and growth during the quantum dot synthesis stage, forming strong chemical bonds with the perovskite quantum dots, stabilizing the crystal structure, suppressing phase transitions, and effectively passivating defects on the crystal surface, thereby suppressing non-radiative recombination processes, accelerating radiative recombination rates, and significantly improving the luminescence efficiency and stability of perovskite quantum dots. The strong anchoring effect of the ionic cyclodextrin passivation layer is maintained during subsequent processing, constituting a key factor in performance transfer.

[0009] S12. Cesium carbonate (Cs2CO3) and oleic acid (OAc) are mixed and stirred until the reaction is complete to obtain a clear and transparent cesium oleate solution. S13. Under stirring conditions, inject the cesium oleate solution of S12 into the precursor solution of step S11. After the reaction, collect the precipitate to obtain perovskite quantum dots based on ionic cyclodextrin ligands.

[0010] This invention first prepares a stable precursor solution by dissolving lead halide salt (PbX2) and ionic cyclodextrin ligands in a polar solvent at room temperature. Then, a cesium oleate solution is injected into this system, and after reaction, the precipitate is collected to obtain perovskite quantum dots. Dispersing the obtained quantum dots in a non-polar solvent can further produce a quantum dot luminescent solution with high luminescence performance. Based on this quantum dot solution, various derivative multifunctional products can be further prepared. For example, combining this quantum dot solution with different polymer matrices can produce solid fluorescent powders with excellent luminescence performance (photoluminescence quantum yield up to 98.4%), as well as large-area transparent luminescent films with high transmittance and good flexibility (e.g., up to 15 cm × 20 cm). In summary, this invention provides a complete technical solution that starts from material synthesis and can continuously retain the excellent properties of the material throughout the entire process of preparing multi-form products. This solution has the outstanding advantages of mild reaction conditions, simple preparation steps, excellent product performance, and easy large-scale scaling, laying a solid foundation for the practical application of perovskite quantum dots.

[0011] Preferably, the cationic cyclodextrin includes aminocyclodextrin, quaternized cyclodextrin, and guanidinocyclodextrin; the anionic cyclodextrin includes carboxylated cyclodextrin, sulfonated cyclodextrin, and phosphorylated cyclodextrin; and the zwitterionic cyclodextrin is a cyclodextrin molecule that simultaneously carries both cationic and anionic groups. The polar solvent includes one or more of 2-methyltetrahydrofuran (MeTHF), tetrahydrofuran (THF), N-methylpyrrolidone (NMP), 2-methoxyethanol (2-ME), γ-butyrolactone (GBL), acetonitrile (ACN), ethyl acetate (EA), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0012] More preferably, the ionic cyclodextrin includes quaternary ammonium cationic β-cyclodextrin and sodium sulfonyl-β-cyclodextrin; the nonpolar solvent includes cyclohexane, n-hexane, toluene, and dichloromethane.

[0013] Preferably, the molar concentration of the lead halide precursor solution is 0.01-1.00 M; and the molar ratio of PbX2 to OAmX in the precursor solution is 1:1. Of course, other non-stoichiometric ratios that form a perovskite structure with cesium oleate can also be used.

[0014] Preferably, the molar ratio of the ionic cyclodextrin to the lead halide salt PbX2 is 1:6-7, or other ratios that can form a stable passivation layer.

[0015] Preferably, the X in the lead halide salt PbX2 and the 9-octadecenylamine halide OAmX is determined according to the target emission wavelength of the quantum dot; in red quantum dots, X is I or a mixture of I and Br; in green quantum dots, X is Br; and in blue quantum dots, X is Br or a mixture of Br and Cl.

[0016] The second aspect of the present invention also provides perovskite quantum dots based on ionic cyclodextrin ligands prepared by the synthesis method described in the first aspect.

[0017] The third aspect of this invention also provides applications of the perovskite quantum dots based on ionic cyclodextrin ligands described in the first aspect, including applications in display, lighting, agricultural optoelectronics, and intelligent greenhouse systems.

[0018] The fourth aspect of the present invention also provides a method for preparing a quantum dot luminescent solution with high luminescence performance, specifically: dispersing the perovskite quantum dots based on ionic cyclodextrin ligands as described in the second aspect in a nonpolar solvent to obtain a quantum dot luminescent solution with high luminescence performance; The nonpolar solvent includes one or more of the following: alkanes (cyclohexane, n-hexane, n-pentane, n-octane, n-tetradecane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbons (carbon tetrachloride, chloroform, dichloromethane, dichloroethane, etc.), and liquid paraffin.

[0019] Preferably, in the high-luminescence-performance quantum dot luminescent solution, the concentration of perovskite quantum dots can be from 4.3 × 10⁻⁶. -6 g / mL expanded to 1.3 × 10 -3 g / mL, which can be adjusted according to actual needs.

[0020] The fifth aspect of this invention also provides a method for preparing a solid fluorescent powder with high luminescence performance, the method comprising the following steps: S21. Dissolve the polymer powder in a non-polar solvent to obtain a polymer suspension; The polymer powder includes polyacrylonitrile (PAN), polyamide (PA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDF), polybenzimidazole (PBI), polyaniline, acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene (PE), polypropylene terephthalate (PTT), polypropylene (PP), polyethylene terephthalate (PET), polycaprolactone (PCL), polyhydroxybutyrate (PHA), polysulfone (PSU), polyethyleneimine (PEI), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polyacrylamide (PAM), and polyethylene glycol (PEG) specialty plastics; the non-polar solvent includes one or more of the following: alkanes (cyclohexane, n-hexane, n-pentane, n-octane, n-tetradecane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbons (carbon tetrachloride, chloroform, dichloromethane, dichloroethane, etc.), and liquid paraffin; S22. The quantum dot luminescent solution prepared by the preparation method described in the fourth aspect is injected into the polymer suspension described in S21. After thorough mixing, the precipitate is collected to obtain solid fluorescent powder.

[0021] The polymer exhibits poor solubility in nonpolar solvents, easily forming a suspension during the synthesis process. The resulting solid fluorescent powder can be processed into films of different sizes using a tableting process.

[0022] Preferably, the selected polymer is PVDF powder and the non-polar solvent is cyclohexane.

[0023] In the method of this invention, the selected PVDF has limited solubility in cyclohexane, insufficient to form a clear and homogeneous solution, and its molecular chains extend to form a suspension. The addition of the perovskite quantum dot solution acts as a nucleating agent, promoting the stable binding and rapid sedimentation of PVDF molecular chains on the perovskite quantum dot surface, thereby forming polymer-encapsulated fluorescent powder. Simultaneously, a wide color gamut coverage is achieved, reaching 96.8% Rec.2020 and 129.6% NTSC standards. Different target emission colors and the preparation of white phosphors can be achieved through simple mixing of red, green, and blue primary color solid phosphors, demonstrating significant application value in white LEDs and wide color gamut display backlighting.

[0024] Preferably, the concentration of the polymer powder in the nonpolar solvent is 0.1-10.0 g / mL.

[0025] Preferably, the volume ratio of the quantum dot luminescent solution to the polymer suspension can be extended from 1:1 to 1:10, and adjusted as needed.

[0026] The sixth aspect of the present invention also provides a method for preparing a large-area transparent light-emitting film or a patterned light-emitting film, the method comprising the following steps: S31. Dissolve the polymer in a non-polar solvent to obtain a transparent and clear polymer solution; The polymers include polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC), poly4-methyl-1-pentene (TPX), and some copolymers such as styrene-methyl methacrylate copolymer (MS), which are conventional optically transparent plastics; the non-polar solvents include one or more of the following: alkanes (cyclohexane, n-hexane, n-pentane, n-octane, n-tetradecane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbons (carbon tetrachloride, chloroform, dichloromethane, dichloroethane, etc.), and liquid paraffin. S32. The quantum dot luminescent solution prepared by the preparation method described in the fourth aspect is thoroughly mixed with the polymer solution described in S31 to form a processable transparent luminescent solution; after standing until it is clear and free of bubbles, it is coated onto the surface of a rigid or flexible substrate using a solution processing method to form a thin film. After the solvent has completely evaporated, the thin film is peeled off from the substrate to obtain a large-area transparent luminescent thin film; or a patterned structure is deposited on the surface of a rigid or flexible substrate using a solution processing method to form a thin film. After the solvent has completely evaporated, the thin film is peeled off from the substrate to obtain a patterned luminescent thin film.

[0027] The solution processing methods include writing, spin coating, drop coating, spray coating, and doctor blade coating or other processing methods; the rigid substrate includes planar glass substrates and curved glass bottle surfaces, and the flexible substrate includes plastic surfaces and paper, etc.

[0028] Preferably, the selected polymer is PS powder and the non-polar solvent is toluene.

[0029] In the method of this invention, the selected PS powder has high solubility in toluene, enabling the formation of a clear and homogeneous solution. On one hand, during the uniform mixing process with the high-performance luminescent perovskite quantum dot solution, the polymer can provide further encapsulation and support for the quantum dots, effectively resisting the degradation of perovskite quantum dots by factors such as heat and oxygen. On the other hand, during the solvent evaporation and film formation process, the molecular chains are densely arranged, resulting in a large-area transparent luminescent film with a light transmittance approaching 90%.

[0030] Preferably, the mass concentration of the polymer solution is 5.0%-33.0%; the volume ratio of the quantum dot luminescent solution to the polymer solution is 1:1-10, which can be adjusted according to actual needs.

[0031] Preferably, the area of ​​the large-area transparent light-emitting film can range from 1.5 cm × 1.5 cm to 15.0 cm × 20.0 cm, and can be adjusted according to actual needs.

[0032] The seventh aspect of the present invention also provides a method for constructing a small-scale intelligent greenhouse, specifically: cutting and assembling a large-area transparent luminescent film prepared by the preparation method described in the sixth aspect, and combining it with a commercial blue light chip to form an intelligent greenhouse module, which is then placed over the plants inside the small greenhouse.

[0033] Compared with the prior art, the beneficial effects of the present invention are: This invention discloses a method for preparing perovskite quantum dots based on ionic cyclodextrin ligands. The method first prepares a precursor solution containing lead halide, 9-octadecenylamine halide, and ionic cyclodextrin in a polar solvent, and then reacts it with cesium oleate at room temperature to obtain high-performance perovskite quantum dots. The obtained quantum dots can be further processed through simple steps such as dispersion, polymer encapsulation, and solution processing to prepare high-luminescent quantum dot luminescent solutions, solid-state fluorescent powders, and large-area transparent luminescent films, etc. The synthesis method of this invention has the advantages of mild conditions, no need for high temperature and inert atmosphere protection, simple operation, good reproducibility, and easy scale-up, providing a reliable technical path for the large-scale, low-cost preparation of high-performance perovskite luminescent materials. Furthermore, the perovskite quantum dots and multi-morphological luminescent products prepared by this invention can be further used to prepare multi-morphological functional products and are suitable for related applications in the field of intelligent optoelectronics.

[0034] Specifically, the present invention is applicable to at least the following fields: (1) High-performance luminescent ink: The quantum dot solution prepared in this invention can be used as a luminescent ink, and its concentration can be 4.3 × 10⁻⁶. -6 g / mL to 1.3×10 -3 It can be flexibly adjusted within the g / mL range and is suitable for a variety of printing and coating processes, providing a material basis for flexible displays and patterned light-emitting devices.

[0035] (2) Fluorescent Powder: This invention achieves solid fluorescent powder by mixing quantum dot solution with polymer suspension, which induces polymer encapsulation and precipitation in situ. The powder exhibits good stability, is easy to store, transport, and process, and can achieve a wide color gamut coverage by simply mixing solid fluorescent powders of red, green, and blue primary colors, reaching 96.8% Rec.2020 and 129.6% NTSC standards. It has outstanding application value in the fields of white LED and wide color gamut display backlighting.

[0036] (3) Large-area transparent light-emitting film: This invention combines quantum dot solution with transparent polymer solution, and then forms a film on rigid and flexible substrates by methods such as drop coating and blade coating to obtain a large-area transparent light-emitting film with a transmittance of nearly 90% and a size of up to 15 cm × 20 cm. The obtained film has excellent optical properties, transmittance and scalable preparation capability.

[0037] (4) Application of intelligent greenhouse supplemental lighting: The large-area transparent luminescent film prepared by this invention can be integrated with a blue light chip to form a simple luminescent greenhouse module, realizing intelligent day and night supplemental lighting in plant cultivation. Experiments have shown that the film can effectively provide light during dark periods, promote plant growth, and demonstrates its practical application potential in agricultural optoelectronic and intelligent greenhouse systems.

[0038] In summary, this invention provides a complete technical solution from room temperature synthesis and multi-morphological material preparation to end-use applications. This solution not only effectively solves the key problems of insufficient stability and easy performance degradation of perovskite quantum dots in the synthesis and processing process, but also lays a solid material foundation for their practical application in multiple fields such as display, lighting, and agricultural optoelectronics. It has significant technological advancement and good application and promotion value. Attached Figure Description

[0039] Figure 1 Photos of perovskite quantum dot luminescent inks based on ionic cyclodextrin ligands, synthesized at room temperature, showing three different main luminescent colors. Figure 2 Comparison of 1H NMR spectra before and after the interaction of ionic cyclodextrin with perovskite; Figure 3 XPS spectra comparison before and after ionic cyclodextrin reduces Pb binding energy on perovskite surface; Figure 4 PLQY is a product with different luminescent morphologies modified by ionic cyclodextrin; Figure 5 Normalized photoluminescence spectrum of perovskite quantum dot luminescent ink synthesized at room temperature and covering the full spectrum; Figure 6 Photographs and color coordinates of perovskite quantum dot fluorescent powders with different emission colors synthesized at room temperature; Figure 7 To determine the color coordinates of different luminescent phosphors and white light powder obtained by simply mixing three primary color perovskite quantum dot fluorescent powders; Figure 8 Photographs of thin films formed by pressing perovskite quantum dot fluorescent powders of different luminescent colors synthesized at room temperature. Figure 9 Photographs of a large-area transparent luminescent film synthesized by room temperature drop coating under photoexcitation and in outdoor natural light environment; Figure 10 The transmission spectrum of a large-area transparent luminescent thin film synthesized at room temperature; Figure 11 A photograph of a large-area transparent luminescent film synthesized by room temperature blade coating under photoexcitation; Figure 12 Photograph of a luminescent thin film prepared by spin coating at room temperature on a flat glass surface; Figure 13 Photographs of luminescent thin films prepared by room temperature spraying on flat and curved glass. Figure 14 Photographs of luminescent patterns fabricated by room temperature handwriting on rigid and flexible substrates; Figure 15 This is a schematic diagram of a small greenhouse device based on a large-area transparent luminescent film; Figure 16 Comparison of plant growth in a small greenhouse based on a large-area transparent luminescent film and actual photos of plants receiving supplemental lighting at night. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0042] To address the challenges of demanding synthesis processes, severe performance degradation during processing, and the difficulty in directly obtaining multi-morphological end materials for perovskite quantum dots, this invention proposes a room-temperature synthesis method for perovskite quantum dots based on ionic cyclodextrin ligands, along with derived techniques for preparing high-performance luminescent inks, fluorescent powders, and large-area transparent luminescent films. This synthesis method yields perovskite quantum dots with excellent luminescent properties at room temperature, solving the synthesis problem of phase stability in all-inorganic red quantum dots (CsPbI3). Furthermore, the ionic cyclodextrin ligands used form strong bonds with the quantum dot surface, effectively passivating surface defects and maintaining a stable passivation layer during subsequent purification, drying, and composite processing, thus achieving high-performance transfer from quantum dot solution to solid-state luminescent materials.

[0043] Based on the aforementioned core material system, high-concentration, printable luminescent inks, polymer-encapsulated fluorescent powders, and large-area, highly transparent flexible luminescent films can be directly prepared through simple dispersion, compounding, and solution processing techniques. The resulting films exhibit a visible light transmittance of nearly 90% and can be patterned on both rigid and flexible substrates using various methods such as scraping, spraying, and handwriting. Furthermore, the resulting flexible luminescent films demonstrate clear application potential in the field of intelligent supplemental lighting; experiments have shown that their nighttime red light supplemental lighting can effectively regulate plant photomorphogenesis and promote healthy growth. Therefore, this invention provides a complete technical solution from mild synthesis and performance preservation to multi-form applications, laying the material and process foundation for the practical application of perovskite quantum dots in displays, lighting, and agricultural optoelectronics.

[0044] The following examples, 1-6, further illustrate the room-temperature synthesis method of perovskite quantum dots based on ionic cyclodextrin ligands, and the multimorphic luminescent materials prepared using this method and their applications.

[0045] Example 1: A room-temperature synthesis method for perovskite quantum dots based on ionic cyclodextrin ligands and preparation of a quantum dot luminescent solution with high luminescence performance. The specific preparation method includes the following steps: (1) Accurately weigh 0.04 mmol PbX2 (X = Cl, I, or Br), 0.006 mmol sodium sulfobutyl-β-cyclodextrin and 0.04 mmol OAmX (X = Cl, I, or Br), dissolve in 1.5 mL EA, and sonicate for 20 minutes (ultrasonic power of 180 W) to obtain lead halide precursor solution; wherein, the control of quantum dot luminescence color is achieved by changing the halogen ratio of the above raw materials: for blue quantum dots, the lead halide precursor solution is prepared by dissolving 0.02 mmol PbCl2, 0.02 mmol PbBr2, 0.02 mmol OAmCl, 0.02 mmol OAmBr and 0.006 mmol sodium sulfobutyl-β-cyclodextrin in 1.5 mL EA; for green quantum dots, the lead halide precursor solution is prepared by dissolving 0.04 mmol PbBr2, 0.04 mmol PbBr2, 0.04 mmol sodium sulfobutyl-β-cyclodextrin and 0.04 mmol sodium sulfobutyl-β-cyclodextrin in 1.5 mL EA. OAmBr and 0.006 mmol of sodium sulfonyl-β-cyclodextrin were dissolved in 1.5 mL of EA; for red quantum dots, the lead halide precursor solution was prepared by dissolving 0.04 mmol of PbI2, 0.04 mmol of OAmI and 0.006 mmol of sodium sulfonyl-β-cyclodextrin in 1.5 mL of EA. (2) Accurately weigh 0.02 mmol Cs2CO3 and 0.14 mL oleic acid, mix and stir for 30 minutes to obtain a clear cesium oleate solution; (3) Under continuous stirring (300 rpm), 0.14 mL of cesium oleate solution was added to 1.5 mL of lead halide precursor solution. After reacting for 10 minutes, the mixture was centrifuged at 10,000 rpm for 5 minutes and the precipitate was collected to obtain perovskite quantum dots based on ionic cyclodextrin ligands. (4) Take 26 mg of the above perovskite quantum dots based on ionic cyclodextrin ligands and disperse them in 20 mL of toluene or cyclohexane to obtain a concentration of 1.3 × 10⁻⁶. -3 g·mL -1 A high-luminescence-performance quantum dot luminescent solution (also known as luminescent ink); by expanding the solvent volume to 12 L, a concentration of 4.6 × 10⁻⁶ can be obtained. -6 g·mL -1 A quantum dot luminescent solution with high luminescent performance.

[0046] Figure 1 The images show photographs of perovskite quantum dot luminescent inks of different primary luminescent colors dispersed in toluene according to this embodiment, including blue quantum dots CsPb(Cl). 0.5 Br 0.5 3, green quantum dots CsPbBr3, red quantum dots CsPbI3 (all three concentrations are 1.3 × 10⁻⁶). -3 g·mL -1 ), and a concentration of 4.6 × 10 -6 g·mL -1 A photograph of the actual red-light perovskite quantum dot luminescent ink.

[0047] Furthermore, following the method of Example 1, perovskite quantum dot luminescent inks of the following different colors were prepared: CsPbCl3, CsPb(Cl... 0.86 Br 0.14 3. CsPb(Cl) 0.75 Br 0.25 3. CsPb(Cl) 0.67 Br 0.33 3. CsPb(Cl) 0.60 Br 0.40 3. CsPb(Cl) 0.54 Br 0.46 3. CsPb(Cl) 0.5 Br 0.5 3, CsPbBr3, CsPb(Br) 0.63 I 0.37 3. CsPb(Br) 0.56 I 0.44 3. CsPb(Br) 0.43 I 0.57 3. CsPb(Br)0.33 I 0.67 3. CsPb(Br) 0.20 I 0.80 3. CsPbI3. Then, photoluminescence spectroscopy tests were performed on all the luminescent inks prepared above, and the results are as follows: Figure 2 As shown in the figure, the spectral data indicates that the luminescent ink prepared by this method can cover the entire visible light spectrum, exhibiting strong adaptability and flexibility, and the target emission wavelength can be adjusted according to actual needs. The narrow half-width of the red emission peak confirms that the quantum dots synthesized at room temperature with the assistance of ionic cyclodextrin ligands possess good phase purity and size uniformity.

[0048] Ionic cyclodextrins play a crucial role in the synthesis and application of perovskite quantum dots. Firstly, in the initial stages of synthesis, ionic cyclodextrins act as highly efficient dispersants, significantly improving the solubility and dispersion uniformity of precursors such as lead halides in polar solvents. This ensures a consistent distribution of precursors in the reaction system, laying an important foundation for the uniform nucleation of quantum dots. Secondly, during the quantum dot formation stage, ionic cyclodextrins can precisely regulate the nucleation and growth kinetics of perovskite crystals. The functional sulfate groups in their molecular structure can form strong chemical bonds with electron-deficient Pb sites on the quantum dot surface. Figure 3 This leads to the formation of a stable coating layer, which on the one hand helps stabilize the perovskite lattice and suppress non-luminescent phase transitions, and on the other hand effectively passivates surface defects and reduces the binding energy. Figure 4 This significantly inhibits non-radiative recombination and promotes radiative recombination, thereby greatly improving the photoluminescence quantum yield (PLQY) and long-term stability of quantum dots. In subsequent material processing and applications, ionic cyclodextrins, due to their strong anchoring effect, ensure that the formed passivation layer remains stable during purification, drying, polymer compounding, and film formation, and is not easily dissociated or lost. This characteristic fundamentally solves the problem of performance degradation caused by the easy detachment of traditional ligands during processing. Figure 5 This enables high-performance transfer from quantum dot solutions to solid-state luminescent materials, providing a key guarantee for the practical application of various types of end products.

[0049] Example 2: Preparation of solid-state fluorescent powder The specific preparation method includes the following steps: (1) Accurately weigh 8.0 g of PVDF powder and dissolve it in 10 mL of cyclohexane. Stir for 30 minutes to obtain a translucent PVDF suspension; (2) Measure 1.0 mL of the solution obtained in Example 1, which has a concentration of 1.3 × 10⁻⁶. -3 g·mL -1A high-luminescence quantum dot luminescent solution (dispersed in cyclohexane) was mixed with 1 mL of the above PVDF suspension. After thorough stirring, the mixture was centrifuged at 8000 rpm for 2 minutes, and the precipitate was collected to obtain solid fluorescent powder.

[0050] Figure 6 The images show photographs and corresponding color coordinates of perovskite quantum dot fluorescent powders with different emission colors prepared in this embodiment. The obtained tri-color fluorescent powders have a wide color gamut coverage and excellent color saturation. Figure 7 This paper showcases the color coordinates of different luminescent phosphors obtained by simply mixing three primary color phosphors, along with the photoluminescence spectrum and physical images of a white phosphor. It demonstrates the ability to prepare different luminescent phosphors while reducing the number of synthesis steps, showcasing their application potential in wide color gamut displays and solid-state lighting. It is evident that a wide color gamut coverage, achieving 96.8% Rec. 2020 and 129.6% NTSC standards, can be achieved by simply mixing red, green, and blue primary color phosphors. Furthermore, this phosphor exhibits good processability and can be processed through molding processes such as tablet pressing. Figure 8 It can be further processed into solid-state light emitters of different shapes and sizes, providing a flexible material morphology basis for device integration and end-product design.

[0051] Example 3: Preparation of large-area transparent light-emitting thin films by drop casting The specific preparation method includes the following steps: (1) Prepare a PS (polystyrene) / toluene polymer solution with a mass fraction of 33.0%; (2) Take 3.0 mL of the high-luminescence quantum dot luminescent solution (dispersed in toluene) prepared in Example 1, mix it with 15.0 mL of the above polymer solution, stir for 20 minutes and let stand until the mixture is clear and free of bubbles; (3) Spread the above mixture evenly on a horizontally placed 15 cm × 20 cm glass substrate, let it stand for 2 hours until the solvent completely evaporates, and then peel the film off the substrate to obtain a large area transparent light-emitting film with a size of 15 cm × 20 cm.

[0052] Figure 9 These are photographs of the obtained large-area transparent luminescent film under photoexcitation and in natural outdoor light. The light transmittance of the film was tested, and the results are as follows. Figure 10As shown in the figure. Test results show that the transmittance of this film is close to 90% in the visible light range, and especially exceeds 90% in the red light region (620–760 nm), exhibiting excellent optical transparency. The combination of high transmittance and good flexibility allows the film to be fitted to different curved surfaces, making it suitable for flexible displays, wearable light-emitting devices, and large-area transparent optoelectronic integration. Furthermore, the solution processing film deposition process demonstrated in this embodiment is simple and mild, possessing the potential to be extended to larger areas and continuous fabrication, providing a practical material solution for the application of perovskite quantum dots in flexible optoelectronics.

[0053] Example 4: Preparation of large-area transparent light-emitting thin film by blade coating The specific preparation method is as follows: (1) Prepare a PS (polystyrene) / toluene polymer solution with a mass fraction of 33.0%; (2) Take 3.0 mL of the high-luminescence quantum dot luminescent solution (dispersed in toluene) prepared in Example 1, mix it with 15.0 mL of the above polymer solution, stir for 20 minutes and let stand until the mixture is clear and free of bubbles; (3) Under an environment of 20℃ and relative humidity of 50±5%, the above mixture was deposited by an automatic blade coating machine to prepare a thin film using glass as a substrate. The blade coating process parameters were set as follows: blade slit width of 1500 μm and coating speed of 20 mm / s. The substrate temperature was controlled at 15-20℃. After the coating was completed, the film was left to stand for 2 hours to allow the solvent to evaporate completely. Then, the film was peeled off from the glass substrate to obtain a large-area transparent light-emitting film.

[0054] Figure 11 This image shows a sample of a light-emitting thin film obtained through a blade coating process. The blade coating process parameters used in this embodiment are precisely controllable, enabling the fabrication of large-area, uniformly thick, and smooth light-emitting thin films. This method exhibits excellent process repeatability and consistency, and is easily extended to continuous, roll-to-roll production, providing a reliable technical path for the large-scale manufacturing of high-performance flexible optoelectronic devices.

[0055] Example 5: Spin coating, spray coating and handwriting preparation of patterned luminescent thin films The specific preparation method is as follows: (1) Prepare a 5.0% PS (polystyrene) / toluene polymer solution; (2) Take 3.0 mL of the high-luminescence quantum dot luminescent solution (dispersed in toluene) prepared in Example 1, mix it with 15.0 mL of the above polymer solution, stir for 20 minutes and let stand until the mixture is clear and free of bubbles; (3) The above mixture is deposited on the substrate by spin coating, spray coating or handwriting method to form a thin film. The film is left to stand for 2 hours until the solvent is completely evaporated to obtain a patterned light-emitting thin film.

[0056] Figure 12 Samples of light-emitting thin films directly formed on flat and curved glass by spin coating were shown. Figure 13 Samples of light-emitting thin films directly formed on flat and curved glass by spraying were displayed. Figure 14 This paper presents luminescent pattern samples prepared by handwriting on the surfaces of flat glass and flexible thin films. This embodiment demonstrates that the perovskite quantum dot composite material system possesses excellent rheological properties and substrate wettability, adaptable to various non-contact or direct writing processes such as spraying and handwriting, enabling rapid customization and high-precision molding of patterns. This method exhibits excellent processing adaptability and pattern design freedom, allowing for the direct preparation of high-resolution, high-brightness luminescent patterns on both rigid substrates (such as flat and curved glass) and flexible substrates (such as plastic films). The spraying method is simple and provides uniform coverage, suitable for rapid coating of large areas or complex curved surfaces; the handwriting method offers good operational intuitiveness and pattern flexibility, enabling the instant drawing of personalized graphics, text, or logos. These two technical approaches not only further confirm the stability and performance retention of the material during processing but also provide a reliable process foundation for its diverse applications in flexible displays, smart decorations, interactive light-emitting devices, and high-security anti-counterfeiting labels, highlighting the advantages of the entire chain of integrated technology from material synthesis to end-device manufacturing.

[0057] Example 6: Constructing a small-scale greenhouse nighttime supplemental lighting device based on a large-area transparent luminescent film The specific preparation method is as follows: The large-area transparent luminescent film prepared in Example 3 was cut and assembled, and used as a smart greenhouse module to cover the plants in a small greenhouse. A commercial ultraviolet light chip (model 3WGH45UV, emission wavelength 365 nm, luminous flux 10-20 lm) was used to excite the red light film to emit light. A schematic diagram of the facility is shown below. Figure 15 As shown, during the day, the module's high light transmittance ensures sufficient natural light penetration, meeting the normal light requirements of plants. At night, the module can actively emit light, providing supplemental red light to plants, thereby effectively improving plant growth performance. The red light band (600–700 nm) highly matches the absorption spectrum of chlorophyll a and b in the red light region, representing the most effective wavelength range for driving the primary photochemical reactions of photosynthesis. Therefore, this supplemental lighting device can effectively extend the daily effective photosynthetic time of plants, theoretically providing a new technical approach to overcoming the limitations of light cycles caused by day-night cycles and seasonal changes in traditional agriculture.

[0058] like Figure 16 As shown, compared with the control group in a conventional greenhouse, the experimental group supplemented with red light at night (using the large-area transparent luminescent film of Example 3 as the greenhouse roof, with nighttime supplementation as shown in the figure) exhibited typical characteristics of compact plant shape, robust stems, and excellent upright growth. This visually verifies the effectiveness of the dynamic supplemental lighting strategy from a plant morphological perspective. The narrow-spectrum red light supplemented at night not only extends the photosynthetic duration as an energy source but also acts as a precise light signal molecule, regulating the photomorphogenesis of the plant and promoting its development towards a healthier and more efficient photosynthetic structure, thereby avoiding ineffective etiolation caused by insufficient light intensity or spectral mismatch. This supplemental lighting strategy based on precise spectral control provides key technical support for achieving high-yield, high-quality, and high-efficiency production in future facility agriculture, and further highlights the broad application prospects of the large-area transparent luminescent film described in this invention in the interdisciplinary field of intelligent agriculture and plant optoelectronics.

[0059] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A room-temperature synthesis method for perovskite quantum dots based on ionic cyclodextrin ligands, characterized in that, Includes the following steps: S11. Dissolve lead halide salt PbX2, 9-octadecenylhalogenated amine OAmX, and ionic cyclodextrin in a polar solvent to obtain a lead halide precursor solution; wherein X is selected from Cl - , Br - Or I - At least one of the following; the ionic cyclodextrin includes cationic cyclodextrin, anionic cyclodextrin, and zwitterionic cyclodextrin; S12. Cesium carbonate (Cs2CO3) and oleic acid (OAc) are mixed and stirred until the reaction is complete to obtain a clear and transparent cesium oleate solution. S13. Under stirring conditions, inject the cesium oleate solution of S12 into the precursor solution of step S11. After the reaction, collect the precipitate to obtain perovskite quantum dots based on ionic cyclodextrin ligands.

2. The room-temperature synthesis method of perovskite quantum dots based on ionic cyclodextrin ligands according to claim 1, characterized in that, The cationic cyclodextrins include aminocyclodextrins, quaternized cyclodextrins, and guanidinocyclodextrins; the anionic cyclodextrins include carboxylated cyclodextrins, sulfonated cyclodextrins, and phosphorylated cyclodextrins; and the zwitterionic cyclodextrins are cyclodextrin molecules that simultaneously possess cationic and anionic groups. The polar solvents include one or more of 2-methyltetrahydrofuran, tetrahydrofuran, N-methylpyrrolidone, 2-methoxyethanol, γ-butyrolactone, acetonitrile, ethyl acetate, dimethylformamide, and dimethyl sulfoxide.

3. The room-temperature synthesis method of perovskite quantum dots based on ionic cyclodextrin ligands according to claim 1, characterized in that, The molar concentration of the lead halide precursor solution is 0.01-1.00 M; in the precursor solution, the molar concentration ratio of PbX2 to OAmX is 1:

1.

4. Perovskite quantum dots based on ionic cyclodextrin ligands prepared by the synthesis method described in any one of claims 1-3.

5. The application of perovskite quantum dots based on ionic cyclodextrin ligands as described in claim 4, characterized in that, Applications include displays, lighting, agricultural optoelectronics, and intelligent greenhouse systems.

6. A method for preparing a quantum dot luminescent solution with high luminescent performance, characterized in that, Dispersing the perovskite quantum dots based on ionic cyclodextrin ligands as described in claim 4 in a nonpolar solvent yields a quantum dot luminescent solution with high luminescence performance. The nonpolar solvent includes one or more of alkanes, aromatic hydrocarbons, halogenated hydrocarbons, and liquid paraffin.

7. A method for preparing a solid fluorescent powder with high luminescent performance, characterized in that, Includes the following steps: S21. Dissolve the polymer powder in a non-polar solvent to obtain a polymer suspension; The polymer powder includes polyacrylonitrile, polyamide, polyvinyl chloride, polyvinylidene chloride, polybenzimidazole, polyaniline, acrylonitrile-butadiene-styrene copolymer, polyethylene, polypropylene terephthalate, polypropylene, polyethylene terephthalate, polycaprolactone, polyhydroxybutyrate, polysulfone, polyethyleneimine, polyvinyl butyral, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, and polyethylene glycol specialty plastics; the non-polar solvent includes one or more of alkanes, aromatic hydrocarbons, halogenated hydrocarbons, and liquid paraffin. S22. The quantum dot luminescent solution prepared by the preparation method described in claim 5 is injected into the polymer suspension described in S21. After thorough mixing, the precipitate is collected to obtain solid fluorescent powder.

8. A method for preparing a large-area transparent light-emitting film or a patterned light-emitting film, characterized in that, Includes the following steps: S31. Dissolve the polymer in a non-polar solvent to obtain a transparent and clear polymer solution; The polymers include polymethyl methacrylate, polystyrene, polycarbonate, and poly4-methyl-1-pentene; the nonpolar solvents include one or more of alkanes, aromatic hydrocarbons, halogenated hydrocarbons, and liquid paraffin. S32. The quantum dot luminescent solution prepared by the method described in claim 5 is thoroughly mixed with the polymer solution described in S31 to form a processable transparent luminescent solution; after standing until it is clear and free of bubbles, it is coated onto the surface of a rigid or flexible substrate using a solution processing method to form a thin film. After the solvent has completely evaporated, the thin film is peeled off from the substrate to obtain a large-area transparent luminescent thin film; or a patterned structure is deposited on the surface of a rigid or flexible substrate using a solution processing method to form a thin film. After the solvent has completely evaporated, the thin film is peeled off from the substrate to obtain a patterned luminescent thin film. The solution processing methods include writing, spin coating, drop coating, spray coating, and doctor blade coating or other processing methods; the rigid substrate includes planar glass substrates and curved glass bottle surfaces, and the flexible substrate includes plastic surfaces and paper, etc.

9. The method for preparing a large-area transparent light-emitting film or a patterned light-emitting film according to claim 8, characterized in that, The mass concentration of the polymer solution is 5.0%-33.0%; the volume ratio of the quantum dot luminescent solution to the polymer solution is 1:1-10.

10. A method for constructing a small-scale intelligent greenhouse, characterized in that, The large-area transparent luminescent film prepared by the preparation method described in claim 8 or 9 is cut and assembled, and combined with a commercial violet light chip to form an intelligent greenhouse module, which is then placed over the plants in a small greenhouse.

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