Phosphorescent material, phosphorescent film and application thereof

Abstract

The present invention discloses a phosphorescent material, a phosphorescent film and its application, wherein the phosphorescent material includes a polymer PMMA-11,12-PSICZ, and its preparation method is as follows: first, a carbazolyl small molecule and 4-chloromethylstyrene are reacted to obtain a functionalized phosphor, and then the functionalized phosphor is copolymerized with methyl methacrylate (MMA) by free radicals to obtain the phosphorescent material, which has excellent luminescent properties and application potential. The present invention also discloses a phosphorescent film obtained from the phosphorescent material, which exhibits excellent luminescent properties, high transparency and good processing properties, and can isolate water and oxygen to a certain extent. Therefore, the present invention applies the film to a new green screen printing technology in water, and compared with traditional screen printing technology, the screen printing method in the present invention can realize screen printing in an aqueous environment, with a simple transfer process, does not contain any harmful ink, and is environmentally friendly, with good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of organic room temperature phosphorescent luminescent materials, in particular to a phosphorescent material, a phosphorescent film and applications thereof. Background Art

[0002] As a fascinating luminescence phenomenon, room temperature phosphorescence has become one of the research hotspots in the field of material luminescence due to its remarkable characteristics such as large Stokes shift, long lifetime, and full-color gamut luminescence. Recently, a clear trend is emerging, that is, the research focus is shifting from inorganic phosphorescent materials with harsh preparation conditions, scarce metal resources and high toxicity for biological applications to organic phosphorescent materials with good biocompatibility, easy processing and low cost. Generally speaking, organic long-life room temperature phosphorescence is generated by the radiative decay of triplet excitons. However, in the current phosphorescent system, the transition from the lowest excited singlet state (S1) to the triplet state (T n ) and the long-lived triplet state (T n ) makes it difficult to achieve organic room-temperature phosphorescence with high brightness, long lifetime, and high quantum yield. According to current research, methods such as crystal engineering, host-guest doping, H-aggregation, supramolecular assembly, and polymerization have been proposed to obtain long-lived organic room-temperature phosphorescence by promoting the ISC of singlet to triplet states and suppressing the non-radiative transition of triplet excitons. Among them, polymer-based room-temperature phosphorescent materials have attracted great interest in molecular design rules and enhancement strategies due to their easily processable flexible long chains and stable phosphorescent emission. The corresponding polymer-based films also have excellent luminescence properties and processing properties.

[0003] Currently, the application of room-temperature phosphorescent materials is often limited to information security and encryption under atmospheric conditions. Therefore, there is an urgent need to develop new technologies to expand the application range of phosphorescent materials. Screen printing technology, with its advantages of fast printing speed, low cost, bright colors, and long shelf life, is gaining increasing recognition across the industry. However, traditional screen printing technology relies on harmful inks and volatile organic solvents, which often cause significant harm to construction workers and the surrounding environment. Therefore, the development of a green, ink-free screen printing technology is crucial. Furthermore, traditional ink-free screen printing technology is difficult to implement in aqueous environments, making it incapable of covert anti-counterfeiting and display applications in specialized environments. Therefore, the development of a new type of phosphorescent material for green screen printing technology is particularly important. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a phosphorescent material to solve the problems of low brightness and short phosphorescence life of the existing phosphorescent materials.

[0005] Furthermore, the present invention also provides a method for preparing the phosphorescent material, which solves the problems of harsh preparation conditions and high cost of existing organic room temperature phosphorescent materials.

[0006] Furthermore, the present invention also makes the phosphorescent material into a phosphorescent film, and uses the phosphorescent film in a green screen printing technology in an aquatic environment to solve the problems of ink pollution and inability to print in an aquatic environment in the existing screen printing method.

[0007] Furthermore, the present invention provides applications of the phosphorescent film in the fields of concealed anti-counterfeiting and display.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A phosphorescent material comprising a polymer having the following structure:

[0010]

[0011] Among them, x>300, y>3.

[0012] Further, its synthetic route is as follows:

[0013] S1. Synthesis of functionalized phosphor 11,12-SICZ:

[0014]

[0015] S2. Synthetic polymer PMMA-11,12-PSICZ:

[0016]

[0017] Furthermore, the preparation steps specifically include:

[0018] S1. Synthesis of functionalized phosphor 11,12-SICZ:

[0019] 11,12-dihydroindole[2,3-a]carbazole, potassium hydroxide, and tetrahydrofuran were added to a reaction vessel and stirred at 65°C for 20 minutes under condensation reflux conditions. 4-chloromethylstyrene was then slowly added to the reaction vessel and stirred at 65°C for 12 hours. Finally, the resulting product was reprecipitated in n-hexane, and the precipitate was washed and dried to obtain the functionalized phosphor 11,12-SICZ.

[0020] S2. Synthetic polymer PMMA-11,12-PSICZ:

[0021] The functionalized phosphor obtained in step S1, methyl methacrylate, and N,N-dimethylformamide were added to a reaction vessel. After dissolving, azobisisobutyronitrile was added and mixed thoroughly. The mixture was allowed to react under an inert atmosphere at 65°C for 48 hours. The resulting product was precipitated in deionized water, filtered, and the solid was reprecipitated with N,N-dimethylformamide. The solid was removed and dried to obtain the polymer PMMA-11,12-PSICZ. The drying step was performed under vacuum at 65°C for 24 hours. The N,N-dimethylformamide provided a reaction environment.

[0022] Furthermore, the molar ratio of the 11,12-dihydroindole[2,3-a]carbazole, potassium hydroxide and 4-chloromethylstyrene is 1:4:3.

[0023] Furthermore, the molar ratio of the functionalized phosphor to methyl methacrylate is 1:200-1800.

[0024] Furthermore, the added amount of the azobisisobutyronitrile is 1% of the total mass of the functionalized phosphor and methyl methacrylate.

[0025] A phosphorescent film is prepared using the aforementioned phosphorescent material. The specific steps include: dissolving the aforementioned polymer, applying the solution to a mold, and drying the resulting phosphorescent film. The solvent used is N,N-dimethylformamide, and the concentration of the dissolved polymer is 30g / L. The drying temperature is 85°C for 30 minutes. The mold can be a quartz plate or a release cloth.

[0026] The invention discloses an application of a phosphorescent film, wherein the phosphorescent film is used in the field of green screen printing technology in a water environment and concealed anti-counterfeiting technology.

[0027] Further, the steps of screen printing are:

[0028] (1) placing the phosphorescent film in a container filled with water, and then placing the screen printing plate outside the container;

[0029] (2) The pattern on the screen printing plate is transferred to the phosphor film by ultraviolet light irradiation, thus completing the screen printing process. The wavelength of the ultraviolet light is 365 nm, and the ultraviolet light irradiation time is 5 seconds.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention proposes a new strategy for preparing phosphorescent materials, which can effectively promote intersystem crossing and stabilize triplet excitons. First, a carbazole phosphor with excellent luminescence properties is functionalized, and then the functionalized phosphor is free radical copolymerized with methyl methacrylate to insert the phosphor into the polymer molecular chain, reducing the vibrational relaxation of the triplet exciton. In addition, the introduction of carbonyl groups in methyl methacrylate effectively promotes intersystem crossing from the excited singlet state to the excited triplet state. Thereby, a synergistic enhancement of the phosphorescence lifetime, phosphorescence quantum yield and brightness is achieved. The phosphorescent film prepared by the phosphorescent material of the present invention has an afterglow brightness of up to 1981.1 mcd / m 2 , the phosphorescence lifetime can reach 1802.0ms.

[0032] 2. The phosphorescent film produced by this invention exhibits excellent luminescence and processing properties, and can isolate water and oxygen to a certain extent, making it suitable for green screen printing in aquatic environments. Compared to traditional screen printing techniques, this green screen printing technology does not contain harmful inks or volatile organic solvents, making it environmentally friendly. Furthermore, the latent information revealed on the polymer film by UV irradiation can be used for covert anti-counterfeiting and display applications in aquatic environments. This opens up new avenues for developing polymer materials with excellent luminescence properties and exploring related applications under various environmental conditions.

[0033] 3. The organic polymer phosphorescent material prepared by the present invention overcomes the shortcomings of inorganic phosphorescent materials, such as the scarcity of rare earth element resources and high biological toxicity. Compared with other organic phosphorescent materials, the present invention overcomes the problems of harsh preparation conditions, high brittleness, and poor stability in the process of preparing phosphorescent materials using crystal engineering, as well as the shortcomings of host-guest doped phosphorescent materials that are prone to phase separation and difficult processing. More importantly, the high-brightness, long-life phosphorescent film of the present invention has a low production cost and a simple preparation process. It not only enriches the preparation methods of polymer room temperature phosphorescent materials, but also provides new theoretical guidance and technical support for the simple and efficient industrial production of polymer room temperature phosphorescent films with excellent luminescent properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the H NMR spectrum of the functionalized phosphor 11,12-SICZ in Example 1 of the present invention;

[0035] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the polymer PMMA-11,12-SICZ in Example 1 of the present invention;

[0036] Figure 3 This is a photo of the phosphorescence of the phosphorescent film in Example 6 of the present invention under a 365nm ultraviolet lamp;

[0037] Figure 4The phosphorescence spectrum of the phosphorescent film in Example 6 of the present invention when excited at 365 nm;

[0038] Figure 5 This is the phosphorescence lifetime decay curve of the phosphorescent film in Example 6 of the present invention when excited at 365 nm;

[0039] Figure 6 This is the afterglow decay curve of the phosphorescent film with a copolymerization ratio of 1:1000 in Example 6 of the present invention;

[0040] Figure 7 Schematic diagrams of Application Example 1 and Application Example 2 of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the embodiments.

[0042] The numerical ranges herein are understood to specifically disclose every intervening value between the upper and lower limits of the range. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in that stated range is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. Although the present invention has only described preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail. As used herein, "comprising", "including", "having", "containing", etc. are all open-ended terms, meaning including but not limited to.

[0044] Unless otherwise specified, the experimental methods used in the present invention are all conventional methods.

[0045] Unless otherwise specified, the materials, reagents, etc. used in the present invention can be purchased or synthesized by known methods.

[0046] The quantitative tests in the present invention were repeated three times and the results were averaged.

[0047] 1. Implementation

[0048] Example 1

[0049] A method for preparing a phosphorescent material comprises the following steps:

[0050] (1) Synthesis of functionalized phosphor 11,12-SICZ

[0051] 11,12-Dihydroindole[2,3-a]carbazole (10 mmol, 2.56 g), KOH (40 mmol, 2.24 g), and tetrahydrofuran (60 mL) were added to a 150 mL three-necked flask and stirred at 65°C under reflux for 20 minutes. 4-Chloromethylstyrene (3.5 mL) was then added to the solution and stirred under the same conditions for another 12 hours. Upon completion of the reaction, the solution was wine red. The resulting product was precipitated in n-hexane (1000 mL) and then filtered to obtain a pale yellow powder. The pale yellow powder was washed again with water. The above two washing steps were repeated three times. Finally, the product was dried in a vacuum oven at 65°C for 24 hours to obtain the functionalized phosphor 11,12-SICZ.

[0052] (2) Synthetic polymer PMMA-11,12-PSICZ

[0053] The successfully synthesized phosphor 11,12-SICZ (0.230 g), methyl methacrylate (10 mL), and N,N-dimethylformamide (25 mL) were added to a 100 mL polymerization tube. After dissolution, the initiator azobisisobutyronitrile (0.097 g) was added and mixed thoroughly. The tube was repeatedly evacuated and filled with argon five times to evacuate the gas, and the mixture was stirred at 65°C for 48 hours. The solution was initially clear and transparent, but with increasing reaction time, the viscosity increased, while the color did not change significantly. After the reaction, the resulting product was precipitated in a beaker containing 1000 mL of deionized water. The solid was then filtered and re-dissolved in N,N-dimethylformamide (5 mL) for reprecipitation. The solid was removed and dried in a vacuum oven at 65°C for 48 hours to obtain the polymer PMMA-11,12-PSICZ.

[0054] Examples 2-5

[0055] Examples 2-5 provide methods for preparing high-brightness, long-life polymer room-temperature phosphorescent materials. The preparation methods are similar to those in Example 1, except that the ratio of the functionalized phosphor to methyl methacrylate is different. Specific examples are shown in Table 1:

[0056] Table 1 Amount of raw materials added in Examples 1-5

[0057]

[0058] Example 6

[0059] A method for preparing a phosphorescent film, comprising the following steps:

[0060] The phosphorescent materials obtained in Examples 1-5 were prepared into 30 g / L solutions using N,N-dimethylformamide as the solvent. The resulting solutions were then drop-coated onto a quartz wafer or a release cloth and dried at 85°C for 30 minutes to obtain the corresponding polymer phosphorescent films P1-P5 made from the corresponding phosphorescent materials in Examples 1-5.

[0061] 2. Result detection and analysis

[0062] In order to verify whether the phosphor 11,12-SICZ in Example 1 was successfully synthesized, the H NMR spectra of the raw materials and products in step (1) of Example 1 were as follows: Figure 1 As shown, the H signal of the raw material at 11.07 ppm comes from -NH, and the H signal at 7-8.5 ppm comes from the carbazole aromatic ring, with an integrated intensity ratio of 1:5. The H signal of the product at 5.2-6.8 ppm comes from -CH=CH2 and -CH2, and the H signal at 6.8-8.3 ppm comes from the aromatic ring, with an integrated intensity ratio of 5:9. This indicates that the phosphor 11,12-SICZ has been successfully synthesized and has the following structure:

[0063]

[0064] The polymer PMMA-11,12-PSICZ in Example 1 was subjected to nuclear magnetic resonance hydrogen spectrum detection, and the detection results are as follows: Figure 2 As shown, the chemical shift of part a comes from the functionalized phosphor 11,12-SICZ, and the chemical shift of part b comes from methyl methacrylate. Figure 2 It can be seen that the obtained product has the following structure:

[0065]

[0066] Under room temperature and atmospheric conditions, the polymer phosphorescent film obtained in Example 6 was irradiated with a 365 nm ultraviolet lamp. Figure 3 As shown, from the photos taken after removing the excitation light source, it can be observed that the afterglow time of polymers with different ratios is different. As the molar ratio of the functionalized phosphor to methyl methacrylate decreases, the afterglow time shows a trend of first increasing and then decreasing, reaching the optimal value when the molar ratio is 1:1000.

[0067] The photophysical properties of the polymer phosphorescent film obtained in Example 6 were tested using a spectrometer to obtain the phosphorescent emission spectrum as shown in FIG. Figure 4 As shown in the figure, the phosphorescence intensity of the polymer phosphorescent film also shows a trend of first increasing and then decreasing, reaching the best when the molar ratio is 1:1000, which is consistent with the visual observation results. Figure 5 The phosphorescence lifetime decay curve further confirms that this ratio is the optimal ratio for polymer copolymerization, and the maximum phosphorescence lifetime is 1802.0ms.

[0068] Figure 6 The afterglow time decay curve shows that the afterglow brightness of the polymer phosphorescent film with a copolymerization ratio of 1:1000 in Example 6 is 1981.1 mcd / m 2 .

[0069] 3. Application of phosphorescent films

[0070] Application Example 1: Application of phosphorescent film in green screen printing technology in water environment

[0071] Place any of the phosphorescent films prepared in Example 6 in a container filled with water, and place the screen printing plate outside the container. Then, transfer the pattern on the screen printing plate to the phosphorescent film by irradiating it with ultraviolet light, and withdraw the light after 5 seconds. Print the "butterfly", "lotus" and "CQUT" patterns on the phosphorescent film as shown in Figure 2. Figure 7 As shown in b. Since the prepared phosphorescent film is very transparent and can isolate water and oxygen, the pattern printed in water shows high clarity and brightness. In addition, as Figure 7 The polymer phosphorescent film's resolution was tested using a USAF 1951 resolution plate, yielding a high resolution of 8 lp / mm. These results demonstrate the enormous potential of the phosphorescent film in display imaging and its potential for covert anti-counterfeiting and display applications in a variety of environments.

[0072] Application Example 2: Application of phosphorescent film in concealed anti-counterfeiting labels

[0073] like Figure 7 c. Dissolve the phosphorescent material obtained by any of the methods in Examples 1-5 in a DMSO solution to prepare phosphorescent ink, which is used to draw anti-counterfeiting patterns of "lightning", "flowers", and "smiley faces" on kraft paper labels. Next, place the phosphorescent anti-counterfeiting label on a heating table at 85°C for only 2 seconds, and the hidden anti-counterfeiting label is ready. The drawn anti-counterfeiting pattern will not be detected under sunlight. Only when it is irradiated with 365nm ultraviolet light for 5 seconds will the anti-counterfeiting pattern appear, and there will be blue phosphorescence that lasts for 15 seconds. It can be seen that it is convenient and effective to use the phosphorescent film prepared by the present invention for hidden anti-counterfeiting technology.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A phosphorescent material, characterized in that: A polymer comprising the following structure: Among them, x>300, y>3.

2. The phosphorescent material according to claim 1, characterized in that: Its synthetic route is as follows: S1. Synthesis of functionalized phosphor 11,12-SICZ: S2. Synthetic polymer PMMA-11,12-PSICZ:

3. The phosphorescent material according to claim 2, characterized in that: The preparation steps specifically include: S1. Synthesis of functionalized phosphor 11,12-SICZ: 11,12-dihydroindole[2,3-a]carbazole, potassium hydroxide, and tetrahydrofuran were added to a reaction vessel and stirred at 65°C for 20 minutes under condensation reflux conditions. 4-chloromethylstyrene was then slowly added to the reaction vessel and stirred at 65°C for 12 hours. Finally, the resulting product was reprecipitated in n-hexane, and the precipitate was washed and dried to obtain the functionalized phosphor 11,12-SICZ. S2. Synthetic polymer PMMA-11,12-PSICZ: The functionalized phosphor, methyl methacrylate, and N,N-dimethylformamide obtained in step S1 are added to a reaction vessel, dissolved, and then azobisisobutyronitrile is added and mixed evenly. The mixture is reacted under an inert atmosphere at 65°C for 48 hours. Finally, the resulting product is precipitated in deionized water, the solid is removed by filtration, and reprecipitated with N,N-dimethylformamide. The solid is removed and dried to obtain the polymer PMMA-11,12-PSICZ.

4. The phosphorescent material according to claim 3, characterized in that: The molar ratio of the 11,12-dihydroindole[2,3-a]carbazole, potassium hydroxide and 4-chloromethylstyrene is 1:4:

3.

5. The phosphorescent material according to claim 3, characterized in that: The molar ratio of the functionalized phosphor to methyl methacrylate is 1:200-1800.

6. The phosphorescent material according to claim 3, characterized in that: The added amount of the azobisisobutyronitrile is 1% of the total mass of the functionalized phosphor and methyl methacrylate.

7. A phosphorescent film, characterized in that: The phosphorescent material according to claim 1 is used for preparation, and the specific steps include: dissolving the phosphorescent material according to claim 1, dripping it on a mold, and drying it to obtain a phosphorescent film.

8. An application of a phosphorescent film, characterized in that: The phosphorescent film according to claim 7 is used in the green screen printing technology and the hidden anti-counterfeiting technology in an aquatic environment.

9. The use of the phosphorescent film according to claim 8, characterized in that: The steps of screen printing are: (1) placing the phosphorescent film in a container filled with water, and then placing the screen printing plate outside the container; (2) The pattern on the screen printing plate is transferred to the phosphor film by ultraviolet light irradiation, thus completing the screen printing process.

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