Visible-light-excited room-temperature phosphorescent composite material and application thereof in traffic license plate and sign board

Abstract

The invention relates to a visible-light-excited room-temperature phosphorescent composite material and application of the visible-light-excited room-temperature phosphorescent composite material in traffic license plates and signs. The room-temperature phosphorescent composite material comprises a film-forming polymer, a sensitizer and an organic phosphorescent material, the mass ratio of the polymer to the sensitizing agent to the organic phosphorescent material is (80-99.8): (0.1-10): (0.1-10). According to the invention, the sensitizer with a specific structure is adopted, so that the comprehensive performance, such as phosphorescence intensity, phosphorescence quantum yield, phosphorescence lifetime, afterglow decay time and the like, of the ultraviolet-excited phosphorescence material is greatly improved under visible light. Furthermore, the room-temperature phosphorescent composite material is applied to the automobile license plate and the traffic sign, so that the technical effects of maintaining phosphorescent emission for a long time and forming higher definition and resolution with the environment can be realized, the road license plate recognition and management work is simplified, and the driving vigilance of a driver is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting materials. More particularly, it relates to a visible light-excited room temperature phosphorescent composite material and its use in traffic license plates and signboards. BACKGROUND

[0002] Traditional motor vehicle license plates are composed of a substrate layer, an ultraviolet-resistant protective coating, a protective layer, etc. Among them, the ultraviolet-resistant protective coating bears the core function of the license plate, which can reflect light through the internal micro-column or micro-prism structure, so that the license plate remains visible within 100 meters at night, and traffic signboards also have similar ultraviolet-resistant structures. However, traditional motor vehicle license plates and traffic signboards do not have the performance of delayed light emission, and traffic signboards cannot be clearly identified after leaving the range of car lights in a dark environment; the distinction between the ultraviolet-resistant protective coating and the corresponding substrate layer is also limited, which can cause difficulties in algorithm recognition.

[0003] Organic room temperature phosphorescent materials can effectively improve the visibility of motor vehicle license plates and traffic signboards. Since the radiation transition from triplet state to singlet state in organic room temperature phosphorescent materials has spin-forbidden property, the luminescence lifetime can reach milliseconds or even seconds, forming sustained light emission, which can be noticed and identified by the human eye. Therefore, organic room temperature phosphorescent materials have become a commonly used ultraviolet-resistant protective material in the ultraviolet-resistant protective coating of motor vehicle license plates or traffic signboards.

[0004] Visible light is a common light source in daily life, which is safe and gentle. Developing visible light-excited room temperature phosphorescent materials is of great significance for the popularization and application of room temperature phosphorescence. However, the reported visible light-excited room temperature phosphorescent materials at present stage usually sacrifice phosphorescent properties as a trade-off; and the molecular design is difficult, and its performance is difficult to predict. The excitation efficiency of ultraviolet light-excited room temperature phosphorescent materials under visible light is very poor, and the luminescence intensity and luminescence lifetime are also low, which makes it difficult to be applied in practice. Therefore, how to make the existing ultraviolet light-excited organic phosphorescent materials be excited efficiently under visible light has become a technical problem to be solved. SUMMARY

[0005] In view of the above existing technical problems, the primary purpose of the present application is to provide a visible light-excited room temperature phosphorescent composite material.

[0006] The second purpose of the present application is to provide a preparation method of the above-mentioned visible light-excited room temperature phosphorescent composite material.

[0007] The third purpose of the present application is to provide the application of the above-mentioned visible light-excited room temperature phosphorescent composite material in the field of automobiles and road traffic.

[0008] The fourth purpose of the present application is to provide a car license plate.

[0009] The fifth object of the present application is to provide a traffic sign.

[0010] The above-mentioned objects of the present application are achieved by the following technical solutions. The primary object of the present application is to provide a visible light excited room temperature phosphorescent composite material, which comprises a film-forming polymer, a sensitizer and an organic phosphorescent material; the mass ratio of the polymer, the sensitizer and the organic phosphorescent material is 80-99.8:0.1-10:0.1-10; the structure of the sensitizer is as follows: .

[0011] The organic phosphorescent material has the advantages of wide absorption band, high energy utilization efficiency, clear imaging, low toxicity, low cost, rich raw materials and the like, but the excitation of the general organic phosphorescent material needs to absorb ultraviolet electromagnetic waves, and it is impossible or very difficult to be excited by visible light. Therefore, the present application proposes a strategy of adding a sensitizer. By using the sensitizer with high triplet exciton utilization rate, more triplet excitons are injected into the organic phosphorescent material excited by ultraviolet light through intermolecular energy transfer, and then high-efficiency luminescence under visible light excitation is realized, which greatly improves the comprehensive performance of the organic phosphorescent material, such as prolonging the phosphorescent lifetime and improving the phosphorescent intensity.

[0012] The specific structure of the sensitizer provided by the present application can form a strong charge transfer band in the visible light region, ensuring high exciton utilization rate, greatly widening the application range of the organic phosphorescent material, and having the advantages of long luminescence time, high light intensity and the like, and has a wide application prospect. The room temperature phosphorescent composite material can produce long-lifetime high-brightness (lifetime greater than 100 ms, which can be distinguished by naked eyes) phosphorescent emission response under the stimulation of visible light excitation (excitation wavelength 400-700 nm).

[0013] Preferably, the mass ratio of the film-forming polymer, the sensitizer and the organic phosphorescent material is 90-99:1-8:0.2-2; further preferably, the mass ratio of the film-forming polymer, the sensitizer and the organic phosphorescent material is 92-96:2-6:0.2-1. More preferably, the mass ratio of the polymer, the sensitizer and the organic phosphorescent material is 94-95:4-6:0.4-0.6.

[0014] Preferably, the film-forming polymer is selected from one or more of polyethylene, polypropylene, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polystyrene, polyacrylonitrile, acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polylactic acid, polyformaldehyde, polyester, polyphenylene ether, polyphenylene sulfide, polysulfone, polyimide, polyaryletherketone, polycaprolactone, cellulose, polyolefin, polyurethane, polyamide, phenolic resin, epoxy resin, rubber.

[0015] The room temperature phosphorescent composite material provided by the present application takes a film-formable polymer as a substrate, and has the following advantages: (1) The polymer substrate provides a rigid microenvironment, which can effectively inhibit the non-radiative dissipation caused by the movement of the phosphorescent material, and is conducive to improving the room temperature phosphorescent performance; (2) The room temperature phosphorescent composite material based on the polymer substrate is simple to prepare, has good mechanical properties, and flexible processing mode, and can be effectively coated on the key information of the license plate and the road sign, and has strong adhesion; (3) The addition amount of the sensitizer and the phosphorescent material in the polymer is less than 5wt.%, which can achieve the best phosphorescent emission effect. The polymer substrate has a large volume and a wide selection range. The material has high stability and long service life, and therefore the material has low economic cost; (4) The polymer substrate material is used in the license plate and the road sign, which can effectively reduce the quality of the traditional license plate, save the cost, improve the corrosion resistance and the ability to resist adverse environments of the road sign, and is convenient for production, installation and transportation. The material has the advantages of practicality and durability, which are combined with the advantages of the metal material, and the service life of the road sign and the license plate is significantly improved. At the same time, the polymer substrate also provides a stable chemical environment for the phosphorescent material, which can promote the stable work of the phosphorescent material for a long time, prevent quenching, and prevent deterioration caused by oxygen and ultraviolet light.

[0016] Preferably, the organic phosphorescent material is an ultraviolet light-excited organic phosphorescent material; and / or the organic phosphorescent material does not have visible light excitation characteristics.

[0017] Preferably, the organic phosphorescent material is selected from organic phosphorescent materials containing fused ring aromatic hydrocarbons and derivatives thereof; further preferably, the organic phosphorescent material is selected from one or more of pyrene, chrysene, anthracene, fluoranthene, coronene, benzo[A]anthracene, benzo[E]pyrene, benzo[A,L]pyrene, benzo[A,I]pyrene, benzo[G,P]fused dinaphthalene, benzo(G,H,I)perylene, and diphenylbenzo[A,H]anthracene.

[0018] A second object of the present application is to provide a preparation method of the above-mentioned room temperature phosphorescent composite material. The film-formable polymer, the sensitizer, the organic phosphorescent material and the solvent are uniformly mixed, and then dried to volatilize the solvent, so as to obtain the visible light-excited room temperature phosphorescent composite material.

[0019] Preferably, the solvent is selected from one or more of dichloromethane, tetrahydrofuran, toluene, methanol, N,N-dimethylformamide, lithium chloride, N,N-dimethylacetamide, dimethyl sulfoxide, hexafluoroisopropanol, and trifluoroacetic acid.

[0020] Preferably, the drying temperature is 80-130℃.

[0021] The third object of the present application is to provide the application of the above-mentioned room temperature phosphorescent composite material in the field of automobiles and road traffic.

[0022] The current traffic congestion and even paralysis phenomenon occurs frequently, and it is urgent to strengthen the establishment of the supervision system for vehicles, and the core of the establishment of the supervision system for vehicles lies in enhancing the identification and information management level of vehicles; in addition, many traffic accidents are closely related to the reasons such as the improper placement of part of the road warning, the pollution and unclearness of the road sign, and the insufficient light under some conditions, and it is necessary to improve the clarity and resolution of the road sign itself to enable the driver to fully master the early warning information. The room temperature phosphorescent composite material capable of being excited by visible light is used as the coating material of the automobile number plate or the road traffic sign, which can effectively solve the above-mentioned problems. On the one hand, the addition of the coating can significantly improve the clarity and resolution of the number plate, and realize the sufficient capture of the number plate information by the camera; on the other hand, it can effectively improve the clarity and distinguishability of the road sign under bad conditions such as foggy weather or darkness, so that the driver can fully master the early warning information, thereby reducing the traffic accidents caused by the failure of the road sign information transmission.

[0023] The room temperature phosphorescent composite material is applied to the automobile number plate, the room temperature phosphorescent composite material is coated on the number plate information, so that the license plate has the characteristics of room temperature phosphorescent delayed emission while maintaining the basic ultraviolet protection ability. When excited by visible light, the material can realize the phosphorescence emission phenomenon for several seconds. In the application of the license plate, the use of the room temperature phosphorescent composite material significantly promotes the development of vehicle information acquisition and management technology based on high-definition camera shooting. Specifically, the phosphorescent coating on the surface of the license plate emits light under the excitation of the flash, which can form a clear contrast with the surrounding black environment and the license plate substrate without phosphorescent coating, thereby greatly improving the clarity and resolution of the number plate information.

[0024] The use of the room temperature phosphorescent composite material can make the license plate emit room temperature phosphorescence of a specific wavelength under the excitation of sunlight or a flash, greatly simplifying the identification and management of the license plate; especially in the night environment, the technology can significantly improve the efficiency and accuracy of license plate shooting and identification, effectively reduce the cost of vehicle identification and management, and bring convenience to vehicle management, license plate management and information management. In addition, the use of such phosphorescent automobile number plate can also undertake the functions such as speed measurement that the traditional camera cannot realize, which is helpful to promote the development of traffic management equipment towards integration and multifunction, can reduce the cost of equipment, and can improve the feasibility of policy implementation.

[0025] The room temperature phosphorescent composite material can also be applied to a traffic sign, and the room temperature phosphorescent composite material is applied to an ultraviolet resistant layer of the sign, so that the phosphorescent material can continuously emit light even in the case of insufficient light or blocked view caused by a preceding vehicle, and a driver can clearly see the dangerous sign, the driving alertness is effectively improved, and the accident rate is reduced.

[0026] Based on this, a fourth object of the present application is to provide an automobile license plate containing the room temperature phosphorescent composite material.

[0027] Based on this, a fifth object of the present application is to provide a traffic sign containing the room temperature phosphorescent composite material.

[0028] Compared with the prior art, the present application has the following beneficial effects: The present application provides a visible light excited room temperature phosphorescent composite material, which uses a specific structure of a sensitizer to realize efficient light emission of an organic phosphorescent material under visible light excited by ultraviolet light, greatly improving the comprehensive performance of the phosphorescent material, such as phosphorescent intensity, phosphorescent quantum yield, phosphorescent lifetime and afterglow decay time. The visible light excited room temperature phosphorescent composite material is applied to an automobile license plate and a traffic sign, which can maintain phosphorescent emission for a long time, and has a higher clarity and resolution effect with the environment, thereby simplifying road license plate recognition and management work and improving the driving alertness of drivers. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A room temperature phosphorescent spectrum diagram of a phosphorescent material coronene doped film under ultraviolet light and visible light excitation.

[0030] Figure 2 A luminescence schematic diagram of the coronene and the sensitizer doped into the polymer; wherein, Figure 2 A visible light excited room temperature phosphorescent spectrum diagram (excitation wavelength 450 nm) of the polymer substrate, the polymer substrate containing the coronene, and the polymer substrate containing the coronene and the sensitizer in A in the above table; Figure 2 B in the above table is a lifetime decay schematic diagram (excitation wavelength 415 nm) of the polymer substrate containing the coronene and the sensitizer; Figure 2 C in the above table is an afterglow decay picture (excitation wavelength 450 nm) of the polymer substrate containing the coronene and the sensitizer.

[0031] Figure 3 A specific structure of a license plate coated with the room temperature phosphorescent composite material.

[0032] Figure 4Schematic diagram of long-time imaging of license plate based on visible light excitation room temperature phosphorescent composite material in dark environment under flash light.

[0033] Figure 5 Schematic diagram of long-time imaging of license plate based on visible light excitation room temperature phosphorescent composite material in dark environment under flash light. DETAILED DESCRIPTION

[0034] The present application will be further described by the following description of the drawings and specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0035] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0036] Example 1 Visible light excitation room temperature phosphorescent composite material 1. Experimental materials: (1) The phosphorescent material is a perylene, and the structural formula is which can be purchased through commercial channels.

[0037] (2) The structure of the sensitizer is , and the synthesis method is as follows: .

[0038] As shown in the above formula, a 250 mL three-necked flask was prepared, and 4-(4-bromophenyl)-2,6-diphenylpyrimidine (1.47 mmol), 2,7-dimethyl-10H,10'-spiro[perylene-9,9'-anthracene]-10'-ketone (1.16 g, 3.24 mmol) and sodium tert-butoxide (t-BuONa, 0.71 g, 7.35 mmol) were sequentially added. The solid was dissolved in 100 mL of toluene under a nitrogen atmosphere, and tris(dibenzylideneacetone)dipalladium(0) (PD2DBA3, 0.14 g, 0.147 mmol) and tri-tert-butylphosphonium tetrafluoroborate [(t-Bu)3PH]BF4, 0.10 g, 0.350 mmol) were added, followed by reaction at 110°C for 24 h. After the reaction was completed, it was filtered through diatomite, and purified by silica gel column chromatography with dichloromethane / n-hexane (volume ratio 3 / 7). Finally, crystallization was performed with dichloromethane / n-hexane to obtain the sensitizer as a bright green solid, with a yield of 80%.

[0039] The information of the nuclear magnetic hydrogen spectrum, carbon spectrum and mass spectrum of the sensitizer is as follows: 1 H NMR (400 MHz, DMSO- d6) δ 8.89, 8.89, 8.87, 8.87, 8.73, 8.73, 8.72,8.71, 8.71, 8.58, 8.58, 8.57, 8.56, 8.56, 7.98, 7.97, 7.79, 7.79, 7.78, 7.77,7.66, 7.65, 7.65, 7.64, 7.64, 7.62, 7.62, 7.45, 7.45, 7.43, 7.43, 7.41, 7.39,7.34, 7.34, 7.32, 7.32, 7.30, 7.30, 6.80, 6.80, 6.78, 6.77, 6.31, 6.29, 6.04, 6.03, 3.34, 1.88. 13 C NMR (151 MHz, DMSO) δ 164.47, 163.52, 163.50, 155.86,143.43, 138.74, 138.69, 137.46, 136.72, 136.55, 131.56, 131.31, 131.04,130.45, 129.02, 128.90, 128.77, 128.59, 128.17, 128.05, 127.83, 127.49,127.03, 125.46, 124.21, 120.41, 114.43, 110.93, 56.27, 20.04. HRMS (ESI) m / z:[M+H] + Calculated for C 49 H 36 N4, 666.29037, found 666.28962. Anal. Calcd for: C,88.39; H, 5.30; N, 6.31. found C, 88.37; H, 5.42; N, 6.28. 2. Preparation of visible light-excited room-temperature phosphorescent composite materials The preparation method of visible light-excited room temperature phosphorescent composite material includes the following steps: sensitizer and phosphorescent material are blended into an N,N-dimethylacetamide solution containing ethylene-vinyl alcohol copolymer (EVOH, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., poly(vinyl alcohol-co-ethylene), ethylene 32 mol %), wherein the mass ratio of sensitizer, phosphorescent material and ethylene-vinyl alcohol copolymer is 5:0.5:94.5; and dried at 120℃ for 24 h to obtain a thin film doped with phosphorescent material, sensitizer and EVOH, which is the visible light-excited room temperature phosphorescent composite material.

[0040] Comparative Example 1 Comparative Example 1 differs from Example 1 in that no sensitizer was added during the preparation process, and a thin film doped with phosphorescent material and EVOH was prepared.

[0041] Test Example 1 The thin film prepared in Comparative Example 1 was tested for room temperature phosphorescence under different excitations of ultraviolet light 365 nm and visible light 450 nm.

[0042] The experimental results are shown in Table 1 and Figure 1 As shown in Table 1 and

[0043] Test Example 2 The thin films prepared in Example 1 and Comparative Example 1 were tested for room temperature phosphorescence under different excitations of visible light, and the corresponding room temperature phosphorescence performance of the two under different excitation conditions was tested.

[0044] 1. Test method for phosphorescence intensity: The phosphorescence spectrum was tested by the Ocean Optics spectrometer system (MayaPro2000), the excitation light source was visible light (450 nm), and the phosphorescence intensity was based on the peak value of the phosphorescence spectrum read in the origin software.

[0045] 2. Test method for afterglow decay time: The material was excited by 450 nm visible light for 2 s at room temperature, then the visible light source was removed, and the process of the material emitting light gradually decaying with the extension of time was recorded by taking pictures, and the process was recorded by Apple iPhone 12 (1080p HD / 60 fps).

[0046] 3. Test method for phosphorescence decay lifetime: The phosphorescence decay lifetime was tested by the Horiba JY FL-3 spectrometer system (415 nm excitation).

[0047] 4. Test method for phosphorescence quantum yield: The phosphorescence quantum yield (450 nm excitation) can be tested by the external calibration integrating sphere (HAMAMATSU C11347) in the Horiba JY FL-3 spectrometer system.

[0048] Table 1 Comparison of room temperature phosphorescence properties under visible light excitation

[0049] The test results are shown in Table 1 and Figure 2 As shown in Table 1 and Figure 2As shown in A, under the excitation of 450 nm visible light, the sample after sensitization emits bright room temperature phosphorescence, the phosphorescence intensity is 5164 arb.u., and the phosphorescence intensity is increased by 43 times. As shown in Figure 2 B, the sample after sensitization obtains a phosphorescence lifetime of more than 6 s under the excitation of visible light 415 nm, and the phosphorescence lifetime is increased by 6 times. In addition, the phosphorescence quantum yield of the phosphorescent material after being sensitized by the sensitizer is increased by 12 times, and the afterglow decay time is prolonged to 60 s Figure 2 C). It can be seen that by using a sensitizer with high exciton utilization rate, more triplet excitons are injected into the phosphorescent material through intermolecular energy transfer, thereby greatly improving the comprehensive performance of the phosphorescent material under visible light excitation.

[0050] Test Example 3 Experimental method: First, a mixed material of polyurethane ink and room temperature phosphorescent composite material of Example 1 is applied as a character layer on a 1 mm substrate layer (aluminum plate) and a 200 μm reflective layer (a micro-prism structure of PMMA, used for reflecting light on the license plate), with a thickness of about 30 μm. On the character layer, a 50 μm thick ultraviolet protection acrylic is installed as a protective layer for ultraviolet protection and oxidation protection; the acrylic protective layer has an ultraviolet blocking rate of 93.35%, which can effectively prevent the destruction of the phosphorescent material layer by ultraviolet irradiation, and also has a light transmittance of 98.58%, which can allow visible light to fully irradiate and excite the phosphorescent material layer. The specific structure of the license plate coated with room temperature phosphorescent composite material is shown in Figure 3 .

[0051] Experimental results: As shown in Figure 4 , using 450 nm visible light to irradiate and excite the license plate for 2 s, after stopping irradiation, the license plate emits clear yellow-green phosphorescence of characteristic wavelength of about 530 nm in the dark, and the afterglow is still clearly visible after 0.5 s of irradiation light intensity equivalent to the car light. It can be seen that after the material is made into a license plate, it has the advantages of visible light excitation, long afterglow, clear and distinguishable, etc.; while ensuring the persistence and stability of information transmission, it also has the advantages of clearness and high resolution for human eye and machine recognition. After extracting high-resolution images, due to the small wavelength peak width of phosphorescence, the characteristic wavelength can be directly captured, realizing simple and fast computer processing to obtain license plate information for machine recognition. Through a series of processes of light irradiation, camera shooting and algorithm processing, the information such as license plate, location, time, destination and speed of the vehicle can be monitored and managed, which is realized by using the polymer-based room temperature phosphorescent material as the core.

[0052] Test Example 4 The structure and principle of the road sign are similar to those of the license plate. The character layer and ultraviolet-resistant protective layer of the road sign are built according to the method of Test Example 3, and visible light irradiation test is performed.

[0053] The experimental results are shown in Figure 5 As shown in the figure, the composite material shows bright yellow-green phosphorescence when the erected signboard is irradiated with 450 nm excitation light, and a clear long afterglow can be observed after the irradiation is stopped, and the information is still easy to identify after more than ten seconds. The phosphorescent composite material combined with the signboard imaging technology helps the driver to master the road conditions and avoid distraction driving to make the warning information reach the position, so that the traffic is more standardized and orderly.

[0054] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A visible light-excited room-temperature phosphorescent composite material, characterized in that, The room-temperature phosphorescent composite material comprises: a film-forming polymer, a sensitizer, and an organic phosphorescent material; the mass ratio of the polymer, sensitizer, and organic phosphorescent material is 80-99.8:0.1-10:0.1-10; the structure of the sensitizer is as follows: 。 2. The room-temperature phosphorescent composite material according to claim 1, characterized in that, The film-forming polymer is selected from one or more of polyethylene, polypropylene, polymethyl methacrylate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polystyrene, polyacrylonitrile, acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polylactic acid, polyoxymethylene, polyester, polyphenylene ether, polyphenylene sulfide, polysulfone, polyimide, polyaryletherketone, polycaprolactone, cellulose, polyolefin, polyurethane, polyamide, phenolic resin, epoxy resin, and rubber.

3. The room-temperature phosphorescent composite material according to claim 1, characterized in that, The organic phosphorescent material is an organic phosphorescent material excited by ultraviolet light; and / or the organic phosphorescent material does not have visible light excitation characteristics.

4. The room-temperature phosphorescent composite material according to claim 1 or 3, characterized in that, The organic phosphorescent material is selected from organic phosphorescent materials containing polycyclic aromatic hydrocarbons and their derivatives.

5. The room-temperature phosphorescent composite material according to claim 4, characterized in that, The organic phosphorescent material is selected from one or more of pyrene, chloropyrene, anthracene, fluoranthene, benzo[A]anthracene, benzo[E]pyrene, benzo[A,L]pyrene, benzo[A,I]pyrene, benzo[G,P]naphthyl, benzo[G,H,I]perylene, and dibenzo[A,H]anthracene.

6. The method for preparing the room temperature phosphorescent composite material according to any one of claims 1-5, characterized in that, The film-forming polymer, sensitizer, organic phosphorescent material and solvent are mixed evenly and dried to allow the solvent to evaporate, thus obtaining the visible light-excited room temperature phosphorescent composite material.

7. The preparation method according to claim 6, characterized in that, The solvent is selected from one or more of dichloromethane, tetrahydrofuran, toluene, methanol, N,N-dimethylformamide, lithium chloride, N,N-dimethylacetamide, dimethyl sulfoxide, hexafluoroisopropanol, and trifluoroacetic acid.

8. The application of the visible light-excited room temperature phosphorescent composite material according to any one of claims 1-5 in the automotive and road transportation fields.

9. A vehicle license plate, characterized in that, It includes the room temperature phosphorescent composite material according to any one of claims 1-5.

10. A traffic sign, characterized in that, It includes the room temperature phosphorescent composite material according to any one of claims 1-5.

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