Long-afterglow material based on organic ligand modified inorganic fluorescent powder and application of long-afterglow material

Abstract

The invention relates to a long-afterglow material based on organic ligand modified inorganic fluorescent powder and application of the long-afterglow material. The long-afterglow material is formed by compounding an organic small molecule ligand containing carboxyl and / or nitrogen heterocycle and the inorganic fluorescent powder through heating and stirring reaction. The preparation method comprises the following steps: dissolving the organic ligand in an organic solvent, adding the inorganic fluorescent powder, heating, stirring, reacting, separating, and drying. The material has good long afterglow performance, light stability and processing adaptability, and shows thermoluminescence response characteristics. Uric acid modification is taken as an example, the afterglow brightness of red, green and blue of the obtained composite material reaches 1381.3 mcd / m, 76130 mcd / m and 16267 mcd / m respectively, the afterglow intensity is improved by 1.36-1.70 times compared with that of unmodified fluorescent powder, the color coordinate is stable, and the afterglow time is prolonged. An afterglow film, a 3D printing component and an optical temperature detection label developed based on the material can be widely applied to the fields of low-diopter illumination, flexible display, high-temperature real-time monitoring, intelligent agricultural light supplement and the like.

Description

Technical Field

[0001] This invention relates to the field of phosphorescent materials technology, and in particular to a long afterglow material based on organic ligand-modified inorganic phosphors and its applications. Background Technology

[0002] Long-persistent luminescent materials (LPLs) have significant application value in fields such as emergency lighting, information storage, bioimaging, and energy-saving displays. While traditional inorganic long-persistent luminescent materials (such as europium-dysprosium co-doped strontium aluminate) exhibit excellent afterglow performance, they suffer from high density and poor organic compatibility, making effective composite with polymer matrices difficult. They typically require physical mixing or surface coating, leading to high doping levels and insufficient interfacial compatibility, thus affecting the material's mechanical properties and luminous efficiency. Pure organic long-persistent luminescent materials (OLPLs), while possessing advantages such as low toxicity and flexible processing, generally face bottlenecks such as poor environmental stability (easily quenched by oxygen / water) and short afterglow time (typically only seconds to minutes), making it difficult to meet practical application requirements. It is evident that existing long afterglow material systems each have significant shortcomings: although inorganic materials are stable and have strong afterglow, they are difficult to be effectively compatible with organic phases, resulting in products with low luminous efficiency; although organic materials have good processability, their environmental stability and afterglow performance urgently need to be improved, and their preparation conditions are stringent and costly.

[0003] Therefore, how to develop new material design and preparation strategies that combine the efficient and stable luminescence properties of inorganic components with the good processing adaptability of organic components to develop novel composite long afterglow materials with excellent long afterglow performance, outstanding environmental stability and good processability is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a long-afterglow material based on organic ligand-modified inorganic phosphors, thereby solving the key problems of poor compatibility between existing inorganic phosphorescent materials and polymer matrices, which leads to luminous efficiency decay, as well as insufficient environmental stability and short afterglow lifetime of pure organic phosphorescent materials.

[0005] Furthermore, this invention also provides a method for preparing the long-afterglow material based on organic ligand-modified inorganic phosphors. This solves the problems of harsh preparation conditions (requiring high temperature / vacuum environment) and high cost (relying on noble metal complexes or complex synthesis) of existing organic room-temperature phosphorescent materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A long afterglow material based on organic ligand-modified inorganic phosphor is formed by reacting organic ligands and inorganic phosphors through heating and stirring; the organic ligands are small organic molecules containing carboxyl groups and / or nitrogen heterocycles.

[0007] Furthermore, the organic ligand is selected from at least one of 9-carbazoleacetic acid, uric acid, and 3'-methoxydiphenyl-4-carboxylic acid.

[0008] Furthermore, the inorganic phosphor is CaSrS:Eu 2+ SrAl2O4:Eu 2+ ,Dy 3+ or SrSiO3:Eu 2+ ,Dy 3+ .

[0009] Furthermore, the mass ratio of the organic ligand to the inorganic phosphor is 1:(30-100). In specific implementations, the optimal ratio can be dynamically optimized based on performance test results at different mass ratios.

[0010] A method for preparing the above-mentioned long afterglow material based on organic ligand-modified inorganic phosphor includes the following steps: dissolving the organic ligand in an organic solvent, adding the inorganic phosphor, reacting by heating and stirring, separating and drying to obtain the final product.

[0011] Furthermore, the organic solvent is N,N-dimethylformamide, anhydrous ethanol, or methanol.

[0012] An application of the above-mentioned long-afterglow material based on organic ligand-modified inorganic phosphor is specifically: it is used to prepare long-afterglow products, including afterglow films, 3D printed components, or optical temperature sensing tags.

[0013] A long afterglow film is prepared by melt blending and blow molding of raw materials including the above-mentioned long afterglow material based on organic ligand modified inorganic phosphor and a polymer matrix.

[0014] A 3D printed component is formed by fused deposition modeling of a 3D printing filament comprising the aforementioned long afterglow material based on organic ligand-modified inorganic phosphor.

[0015] An optical temperature sensing tag comprising a sensitive coating formed by mixing the aforementioned long-afterglow material based on organic ligand-modified inorganic phosphor with an adhesive and then curing it onto a substrate.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a long-afterglow material based on organic ligand-modified inorganic phosphors. The luminescence performance of the material is significantly improved through the combination of organic ligands and inorganic phosphors. After absorbing light energy, the organic ligands transfer energy to the luminescent centers of the inorganic phosphors (such as the Eu²⁺ pair in SCSE and the Eu²⁺-Dy³⁺ pair in SAOED) via an energy transfer process, and then rapidly release the energy through radiative transitions. Compared to the slow thermal release of charge carriers in traps, the luminescence dynamics dominated by the energy transfer process are significantly faster. This means that the luminescence of the composite material in the initial stage of afterglow mainly originates from the energy transfer between the ligands and the luminescent centers, rather than the recombination of trapped charge carriers. Only after the energy transferred by the ligands is exhausted does the trapping effect gradually dominate the later afterglow. The entire afterglow process is the result of the synergistic effect of the energy transfer process and the trapping effect, allowing the composite material to acquire more energy and thus exhibit superior afterglow performance. Experiments show that, taking uric acid modification as an example, the afterglow brightness of the resulting composite material in red, green, and blue reached 1381.3 mcd / m², 76130 mcd / m², and 16267 mcd / m², respectively. In terms of afterglow intensity, compared with unmodified inorganic phosphor, it was increased by 1.37, 1.70, and 1.36 times, respectively. At the same time, while maintaining the stability of the original emission color and color coordinates, a longer afterglow time was achieved.

[0017] 2. This invention also provides a method for preparing the above-mentioned long-afterglow material based on organic ligand-modified inorganic phosphors. This method overcomes the dependence of traditional high-performance phosphorescent materials on complex crystal engineering or harsh synthesis conditions. The process conditions are mild, requiring only heating and stirring in solution. The operation is simple, the raw materials are readily available, and it has good reproducibility and potential for large-scale production. The organic ligands interact with the inorganic matrix through multi-point binding, enhancing interfacial bonding and energy transfer efficiency, significantly improving luminescence efficiency. At the same time, it avoids the problems of poor compatibility and high doping levels caused by physical blending, providing a low-cost and universal method for achieving high-performance luminescence.

[0018] 3. The composite material obtained by this invention also has good processing adaptability, and based on this composite material, various functional products such as afterglow films, 3D printed components, and optical temperature detection tags have been further developed. These products not only inherit the excellent long afterglow characteristics of the material itself, but also expand its practical applications in low-visibility lighting, high-end anti-counterfeiting, visual sensing, flexible displays, smart agriculture (such as nighttime supplemental lighting films), and high-temperature real-time optical temperature measurement, etc., and build a complete chain application system from basic materials to end products, providing a solid material platform and technical support for the development of multi-color, customized long afterglow devices. Attached Figure Description

[0019] Figure 1These are schematic diagrams of the three long afterglow materials based on organic ligand-modified inorganic phosphors in Examples 1-3 of the present invention. Figure 2 This is a schematic diagram of the structure of the inorganic phosphor SCSE; Figure 3 This is a schematic diagram of the structure of the inorganic phosphor SAOED; Figure 4 This is a schematic diagram of the structure of the inorganic phosphor SSOED; Figure 5 This is a process flow diagram for preparing long afterglow materials according to the present invention; Figure 6 This is a process flow diagram for the preparation of afterglow thin film in Application Example 7 of the present invention; Figure 7 This is a process flow diagram of the preparation of 3D printed components in Application Example 8 of the present invention; Figure 8 This is a process flow diagram of the preparation of the optical temperature detection tag in Application Example 9 of the present invention; Figure 9 This is a schematic diagram illustrating the structure of the present invention for application demonstration; Figure 10 The infrared spectrum of SCSE@UA in Embodiment 4 of the present invention; Figure 11 The infrared spectrum of SAOEDE@UA in Embodiment 5 of the present invention; Figure 12 The infrared spectrum of SSOED@UA in Embodiment 6 of the present invention; Figure 13 These are photographs of the phosphorescence of the composite materials in Examples 4-6 of this invention under a 365 nm ultraviolet lamp. Figure 14 The phosphorescence spectra of SCSE@UA with different mass ratios under a 365 nm ultraviolet lamp in Example 4 of the present invention; Figure 15 The phosphorescence spectrum of SCSE@UA under a 365 nm ultraviolet lamp in Example 4 of this invention; Figure 16 The phosphorescence spectrum of SAOEDE@UA under a 365 nm ultraviolet lamp in Example 5 of this invention; Figure 17 The phosphorescence spectrum of SSOED@UA under a 365 nm ultraviolet lamp in Example 6 of this invention; Figure 18 This is the brightness decay curve of SCSE@UA under a 365 nm ultraviolet lamp in Example 4 of the present invention; Figure 19 This is the brightness decay curve of SAOEDE@UA under a 365 nm ultraviolet lamp in Example 5 of the present invention; Figure 20 This is the brightness decay curve of SSOED@UA under a 365 nm ultraviolet lamp in Embodiment 6 of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the raw materials used are all reagents and materials that can be obtained commercially.

[0021] I. A long afterglow material based on organic ligand-modified inorganic phosphor The core inventive concept of this invention lies in constructing a composite structure through the chemical interaction between organic ligands and inorganic phosphors. The organic ligands act as photosensitizers, sensitizing the luminescent centers of the inorganic phosphors via an efficient energy transfer mechanism, thereby synergistically enhancing the overall long-afterglow performance of the material. This strategy cleverly combines the excellent light-harvesting ability and processability of organic components with the stable and efficient luminescent properties of inorganic components, and based on this, multifunctional application products have been developed.

[0022] Examples 1-3 See Figure 1 This includes three long-afterglow materials based on organic ligand-modified inorganic phosphors (structural schematic diagrams), namely SCSE@UA, SAOED@UA, and SSOED@UA. These long-afterglow materials are synthesized by a heating and stirring reaction of organic ligands and inorganic phosphors. The organic ligand is selected from uric acid (UA). In specific implementations, the organic ligand can also be any one of 9-carbazoleacetic acid and 3'-methoxydiphenyl-4-carboxylic acid.

[0023] The inorganic phosphor is selected from any one of SCSE, SAOED, and SSOED. See also Figure 2 -4 shows the structural diagrams of inorganic phosphors SCSE (red), SAOED (green), and SSOED (blue).

[0024] II. A method for preparing long afterglow materials based on organic ligand-modified inorganic phosphors See Figure 5 The method for preparing the long afterglow material includes the following steps: dissolving the organic ligand in an organic solvent, adding the inorganic phosphor, reacting by heating and stirring, separating and drying to obtain the final product.

[0025] Example 4 Preparation of SCSE@UA composite long afterglow material (red): Weigh 20 mg of uric acid (UA) into a 100 mL beaker, add 60 mL of N,N-dimethylformamide (DMF), and sonicate for 5 minutes to completely dissolve the UA. Then, add 0.6 g of red inorganic fluorescent powder SCSE (CaSrS:Eu) to the solution. 2+ The mixture was stirred continuously at 90 °C for 9 hours. After the reaction, the mixture was filtered, the solid product was collected, and dried in an oven at 80 °C for 12 hours to obtain the long afterglow material SCSE@UA (mass ratio 30:1) based on organic ligand-modified inorganic phosphor. Following this method, SCSE@UA composite materials with mass ratios of 50:1, 100:1, and 200:1 were prepared by adjusting the UA to SCSE ratio.

[0026] Example 5 Preparation of SAOED@UA composite long afterglow material (green): Weigh 12 mg of uric acid (UA) into a 100 mL beaker, add 60 mL of N,N-dimethylformamide (DMF), and sonicate for 5 minutes until completely dissolved. Then, add 0.6 g of green inorganic phosphor SAOED (SrAl2O4:Eu) to the solution. 2 + ,Dy 3+ The mixture was stirred continuously at 80 °C for 9 hours. After the reaction was completed, the mixture was filtered, the solid product was collected, and dried in an oven at 80 °C for 12 hours to obtain the long afterglow material SAOED@UA (mass ratio 50:1) based on organic ligand-modified inorganic phosphor.

[0027] Example 6 Preparation of SSOED@UA composite long afterglow material (blue): Weigh 12 mg of uric acid (UA) into a 100 mL beaker, add 60 mL of N,N-dimethylformamide (DMF), and sonicate for 5 minutes until completely dissolved. Then, add 0.6 g of blue inorganic phosphor SSOED (SrSiO3:Eu) to the solution. 2+ ,Dy 3+ The mixture was stirred continuously at 80 °C for 9 hours. After the reaction was completed, the mixture was filtered, the solid product was collected, and dried in an oven at 80 °C for 12 hours to obtain the long afterglow material SSOED@UA (mass ratio 50:1) based on organic ligand-modified inorganic phosphor.

[0028] III. Applications of Long Afterglow Materials Based on Organic Ligand-Modified Inorganic Phosphors Example 7 See Figure 6 Preparation method of afterglow thin film: Preparation of a red long-afterglow film: 100 g of low-density polyethylene (LDPE) was accurately weighed and physically blended with 1 g of the SCSE@UA (50:1) composite material prepared in Example 4. The mixture was melt-extruded and granulated using a twin-screw extruder at 180 °C. Subsequently, the granules were blown into shape at 180 °C using a blown film extruder to obtain a flexible film that emits a red long-afterglow. The film has controllable thickness and good flexibility and rollability.

[0029] Preparation of green long afterglow film: The preparation process is basically the same as that of red long afterglow film, except that the long afterglow material is the SAOED@UA composite material prepared in Example 5.

[0030] Preparation of blue long-afterglow thin film: The preparation process is basically the same as that of red long-afterglow thin film, except that the long-afterglow material is the SSOED@UA composite material prepared in Example 6.

[0031] Example 8 See Figure 7 Preparation of 3D printed filaments and components: Preparation of Red Long Afterglow 3D Printing Filament and Components: 5 kg of polylactic acid (PLA) was accurately weighed and dry-mixed with 100 g of the SCSE@UA (50:1) composite material prepared in Example 4. The mixture was melt-blended, extruded, cooled, and drawn using a twin-screw extruder at 180 °C to finally produce a red long afterglow 3D printing filament with a diameter of 1.75 mm. Using this filament, finely structured solid components were successfully printed using a fused deposition modeling (FDM) 3D printer based on a pre-set three-dimensional model (such as a safety sign).

[0032] Preparation of green long-afterglow 3D printing filaments and components: The preparation process is basically the same as that of red long-afterglow 3D printing filaments and components, except that the long-afterglow material is the SAOED@UA composite material prepared in Example 5.

[0033] Preparation of blue long-afterglow 3D printing filaments and components: The preparation process is basically the same as that of red long-afterglow 3D printing filaments and components, except that the long-afterglow material is the SSOED@UA composite material prepared in Example 6.

[0034] Example 9 See Figure 8 Preparation of optical temperature detection tags: Preparation of a red long-afterglow optical temperature detection tag: 1 g of the SCSE@UA (50:1) composite material prepared in Example 4 was thoroughly mixed with 5 g of transparent epoxy resin adhesive. The mixture was then coated onto a clean iron substrate and cured at room temperature for 24 hours to form a uniform sensitive coating, thus obtaining the red long-afterglow optical temperature detection tag. This coating can achieve sensitive and visual optical detection of temperature through changes in luminescence intensity based on the thermally excited luminescence effect.

[0035] Preparation of green long-afterglow optical temperature detection tag: The preparation process is basically the same as that of red long-afterglow optical temperature detection tag, except that the long-afterglow material is the SAOED@UA composite material prepared in Example 5.

[0036] Preparation of blue long-afterglow optical temperature detection tag: The preparation process is basically the same as that of red long-afterglow optical temperature detection tag, except that the long-afterglow material is the SSOED@UA composite material prepared in Example 6.

[0037] IV. Performance Testing and Result Analysis Structural characterization: Fourier transform infrared spectroscopy was performed on the composite materials obtained in Examples 4-6, and the results are as follows: Figure 10-12 As shown, compared with the raw material, the composite material exhibits new characteristic absorption peaks at specific wavenumbers, confirming that the organic ligand UA has been successfully modified onto the surface of the inorganic phosphor through chemical action.

[0038] Luminescent properties: The composite materials of Examples 4-6 were irradiated with a 365 nm ultraviolet lamp under ambient temperature and atmospheric conditions. Figure 13 As shown, all composite materials exhibited a bright and persistent afterglow visible to the naked eye after irradiation ceased, and the afterglow duration was longer than that of the unmodified original inorganic phosphor. Phosphorescence spectra were measured using a spectrometer, and the results showed that ( Figure 14-17 After modification with UA, the optimal phosphorescence emission intensity of the composite material was significantly higher than that of the original phosphor. In particular, the sample with a mass ratio of 50:1 (UA:phosphor) exhibited the strongest luminescence intensity.

[0039] Afterglow decay curves: Afterglow decay curves of the composite materials with the optimal ratio (50:1) in Test Examples 4-6 ( Figure 18-20 The results show that UA modification effectively slows down the afterglow decay rate, and the composite material has higher afterglow brightness in the initial stage and a longer afterglow duration.

[0040] V. Application Demonstration 1. Afterglow film (Example 7): like Figure 9As shown in b and c, the afterglow film prepared in Example 7 possesses excellent flexibility, allowing for bending and folding, and is suitable for large-area fabrication. This series of films maintains stable and long-lasting multi-color afterglow emission even after illumination ceases. Furthermore, by pre-fabricating specific patterns (such as QR codes or logos) on their surface, after light excitation and removal of the light source, the patterns remain clearly discernible in the dark due to the material's inherent long afterglow characteristics, exhibiting good display repeatability and stability.

[0041] Furthermore, this type of film can absorb ultraviolet-visible light from sunlight and convert it into afterglow of specific wavelengths, which is continuously released at night. It can be used not only in greenhouses or mulch film systems to provide supplemental lighting at night, promote plant photosynthesis, and extend the effective light duration, but also provides new material support for smart agriculture. Based on these properties, the afterglow film shows broad application potential in fields such as anti-counterfeiting labels, information encryption, flexible displays, decorative lighting, and smart agricultural films, especially providing a feasible material platform for constructing novel visual flexible optoelectronic devices.

[0042] 2. 3D printed components (Example 8): like Figure 9 As shown in left (a), the printed component, after being excited by ultraviolet light, emits bright red, green, and blue afterglow in the dark, exhibiting stable morphology. It not only provides illumination in darkrooms but also enables visual differentiation and information transmission through color combinations. This material demonstrates excellent luminescent stability and mechanical durability during multiple light cycles, making it suitable for various scenarios such as facility path guidance, mine safety signs, educational demonstration models, and visual assistance in low-light environments. It also shows broad application prospects in large-size customized luminous signage, personalized optical decoration, and flexible human-machine interfaces, providing new possibilities for the application of multicolor long-afterglow materials in functional additive manufacturing.

[0043] 3. Optical temperature detection tag (Example 9): like Figure 9 As shown in right a, the optical temperature detection tag prepared in Example 9 exhibits only weak phosphorescence or no luminescence at room temperature. However, when placed on a 100°C heating stage, it can emit significantly enhanced visible phosphorescence, and the luminescence intensity shows a sensitive and reversible change with increasing temperature, gradually increasing to a stable state with prolonged exposure time, thus achieving real-time, visual monitoring of thermal conditions. This tag possesses good thermal stability and reversible luminescence, making it suitable for applications such as overheating warnings for industrial equipment, non-contact temperature distribution indication, and optical sensing in high-risk environments. It provides a new approach for the application of long-afterglow materials in intelligent sensing and functional visual coatings.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A long afterglow material based on organic ligand-modified inorganic phosphor, characterized in that, It is synthesized by reacting organic ligands and inorganic phosphors through heating and stirring; the organic ligands are small organic molecules containing carboxyl groups and / or nitrogen heterocycles.

2. The long afterglow material based on organic ligand-modified inorganic phosphor according to claim 1, characterized in that, The organic ligand is selected from at least one of 9-carbazoleacetic acid, uric acid, and 3'-methoxydiphenyl-4-carboxylic acid.

3. The long afterglow material based on organic ligand-modified inorganic phosphor according to claim 1 or 2, characterized in that, The inorganic phosphor is CaSrS:Eu 2+ SrAl2O4:Eu 2+ ,Dy 3+ or SrSiO3:Eu 2+ ,Dy 3+ .

4. The long afterglow material based on organic ligand-modified inorganic phosphor according to claim 1, characterized in that, The mass ratio of the organic ligand to the inorganic phosphor is 1:(30-100).

5. A method for preparing a long afterglow material based on organic ligand-modified inorganic phosphor as described in any one of claims 1-4, characterized in that, The process includes the following steps: dissolving the organic ligand in an organic solvent, adding the inorganic phosphor, reacting by heating and stirring, separating and drying to obtain the final product.

6. The method for long-afterglow materials based on organic ligand-modified inorganic phosphors according to claim 5, characterized in that, The organic solvent is N,N-dimethylformamide, anhydrous ethanol, or methanol.

7. An application of a long afterglow material based on organic ligand-modified inorganic phosphor as described in any one of claims 1-4, characterized in that, It is used to prepare long afterglow products, including afterglow films, 3D printed components, or optical temperature sensing tags.

8. A long afterglow thin film, characterized in that, It is made from raw materials including the long afterglow material based on organic ligand modified inorganic phosphor as described in any one of claims 1-4 and a polymer matrix through melt blending and blow molding.

9. A 3D printed component, characterized in that, It is made by fused deposition modeling of 3D printed filament containing the long afterglow material based on organic ligand modified inorganic phosphor as described in any one of claims 1-4.

10. An optical temperature sensing tag, characterized in that, It comprises a sensitive coating formed by mixing a long-afterglow material based on organic ligand-modified inorganic phosphor as described in any one of claims 1-4 with an adhesive and then curing it onto a substrate.

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