A flexible organic room temperature phosphorescent material and its preparation method and application

Abstract

The present invention relates to the field of optical material technology, and discloses a flexible organic room temperature phosphorescent material, its preparation method, and application. The preparation method comprises the following steps: dissolving a terpyridine phosphor and a polymer in water to obtain a precursor solution, annealing the precursor solution, and volatilizing the precursor solution to form a film to obtain the flexible organic room temperature phosphorescent material; the present invention uses a terpyridine compound as a phosphor and physically doping it into a polymer matrix to prepare an ultra-long organic room temperature phosphorescent material; and by regulating the doping concentration and type of phosphorescent molecules, the afterglow life and color can be regulated. The required raw materials are inexpensive and readily available, and the prepared material has the advantages of good flexibility, high transparency, and a long phosphorescence life, and has broad application prospects in the fields of afterglow display, information encryption, and anti-counterfeiting.

Description

Technical Field

[0001] The present invention relates to the technical field of optical materials, and in particular to a flexible organic room temperature phosphorescent material and a preparation method and application thereof. Background Art

[0002] Traditional inorganic phosphorescent materials based on aluminates, silicates, and sulfates doped with rare earth metals such as europium (Eu) and dysprosium (Dy) have matured and are widely used. However, the preparation conditions of such inorganic phosphorescent materials are harsh, the cost is high, and they are difficult to process. In contrast, organic room temperature phosphorescent materials based on polymer matrices are more environmentally friendly, have consistent preparation conditions, simple methods, and have better flexibility and transparency. To date, organic room temperature phosphorescence has important application prospects in optoelectronic devices, bioimaging, and information encryption. However, how to efficiently prepare organic room temperature phosphorescent materials with ultra-long afterglow lifetimes remains a problem to be solved by current technology.

[0003] Doping organic fluorophores (carbazole derivatives, boronic acid-modified aromatic compounds) into a polymer matrix that can provide hydrogen bonds can efficiently prepare ultra-long organic room-temperature phosphorescent materials. Professor Zhao Yanli physically doped carbazole derivatives with polyvinyl alcohol to prepare large-area room-temperature organic phosphorescent film materials with an afterglow duration of more than 20 seconds (Large-Area, Flexible, Transparent, and Long-Lived Polymer-Based Phosphorescence Films. J. Am. Chem. Soc. 2021, 143, 13675). Professor Lu Chao's research team used the click reaction of boronic acid groups with polyvinyl alcohol hydroxyl groups to efficiently obtain pure organic and efficient room-temperature phosphorescent materials (Large-Scale Preparation for Efficient Polymer-Based Room-Temperature Phosphorescence via ClickChemistry. Sci. Adv. 2020, 6, eaaz6107).

[0004] However, the phosphorescent molecules used in these materials are complex to design and difficult to synthesize, and the cost is high. Therefore, it is still worth studying and exploring how to use cheap and readily available raw materials to produce organic room-temperature phosphorescent materials with good flexibility, high transparency and long phosphorescence life. Summary of the Invention

[0005] The present invention provides a method for preparing an ultra-long organic room-temperature phosphorescent material that is both flexible and transparent. The preparation conditions are mild, and the required raw materials are cheap and easily available. The prepared material has the advantages of good flexibility, high transparency, and long phosphorescence life, and has broad application prospects in the fields of afterglow display, information encryption, and anti-counterfeiting.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a flexible organic room temperature phosphorescent material comprises the following steps:

[0008] Dissolving a terpyridine phosphor and a polymer in water to obtain a precursor solution, annealing the precursor solution, and volatilizing the precursor solution to form a film to obtain the flexible organic room temperature phosphorescent material;

[0009] The structure of the terpyridine phosphor is any one or more of the following formulae:

[0010]

[0011] That is, in some embodiments, the terpyridine-based phosphor includes any one or more of terpyridine, 4,4',4"-trimethyl-terpyridine, 2,3,5,6-tetrapyridyl-pyrazine, and 4-terpyridine-4'-aniline.

[0012] The present invention uses terpyridine compounds as phosphors, physically doping them into a polymer matrix, and achieving aggregation and motion restriction of phosphorescent molecules through annealing and volatilization film formation to prepare an ultra-long organic room-temperature phosphorescent material. By regulating the doping concentration and type of phosphorescent molecules, the afterglow lifetime and color can be controlled.

[0013] The raw materials of the terpyridine compounds in the present invention are cheap and the synthesis process is simple and easy to obtain. Also, because they are small molecular compounds, compared with polycyclic aromatic compounds, they have fewer conjugated groups with the molecular chains in the polymer matrix, and the obtained room temperature phosphorescent materials are very transparent and flexible.

[0014] In some embodiments, the terpyridine phosphor is any one of terpyridine and 4,4',4"-trimethyl-terpyridine.

[0015] In some embodiments, the terpyridine phosphor is added in an amount of 0.2 to 1.8 wt% of the polymer, such as 0.5 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, or any value therebetween. Simply adding a small amount of the phosphor to the polymer matrix to form a uniform luminescent aggregate can achieve high-intensity, long-life room-temperature phosphorescence emission.

[0016] In some embodiments, the amount of water used is 10-15 times the mass of the polymer.

[0017] In some embodiments, the polymer includes one or more of polyvinyl alcohol, polyacrylic acid, polyacrylamide, and polyacrylonitrile. These polymers contain hydroxyl, amino, or cyano groups that can form multiple hydrogen bonds with terpyridine phosphorescent molecules. This allows the phosphorescent molecules to be evenly dispersed within the polymer matrix. Furthermore, the confining effect of the multiple hydrogen bonds suppresses non-radiative energy dissipation, thereby increasing the lifetime of triplet excitons.

[0018] In some embodiments, the polymer is polyvinyl alcohol and polyacrylamide; in some embodiments, the degree of alcoholysis of the polyvinyl alcohol is not less than 70%; polyvinyl alcohol has good crystallinity, thereby providing a better rigid environment for the phosphor to inhibit the quenching of triplet excitons. The polyvinyl alcohol models used include commercially available 1799, 1788, and 1780, and polyvinyl alcohol 1799 is preferred, which can provide better hydrogen bonding and a rigid environment.

[0019] In some embodiments, the dissolution temperature is 25-105°C, and the dissolution time is 2-60 min. In some embodiments, the dissolution temperature is 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any value therebetween. In some embodiments, the dissolution time is 10 min, 15 min, 20 min, 30 min, 40 min, 50 min, or any value therebetween.

[0020] In some embodiments, the annealing temperature is 40-75°C, and the annealing time is 15-30 min. In some embodiments, the annealing temperature is 50°C, 55°C, 60°C, 65°C, 70°C, or any value therebetween. In some embodiments, the annealing time is 18 min, 20 min, 24 min, 26 min, 28 min, or any value therebetween.

[0021] In some embodiments, the volatilization film forming temperature is 50-75°C and the time is 45-60 minutes. In some embodiments, the annealing temperature is 55°C, 60°C, 65°C, 70°C, or any value therebetween. In some embodiments, the annealing time is 50 minutes, 55 minutes, or any value therebetween.

[0022] In some embodiments, the added amount of the terpyridine phosphor is 0.2-1.8 wt% of the polymer weight, preferably 0.5-1.5 wt%, and further preferably 1.0 wt%. The annealing temperature is 65°C and the annealing time is 15-30 min. The room temperature phosphorescent material obtained under these conditions has a more moderate and uniform particle size of the phosphorescent aggregates, so the afterglow intensity and life are better.

[0023] The present invention also provides a flexible organic room temperature phosphorescent material prepared by the preparation method.

[0024] The flexible organic room temperature phosphorescent material produced by the present invention has a transmittance of no less than 90% and a phosphorescence lifetime of no less than 50 milliseconds. The longest phosphorescence lifetime can reach 543.9 milliseconds. The present invention also provides a method for preparing the flexible organic room temperature phosphorescent material with an ultra-long lifetime. The material also exhibits excellent flexibility and high transparency, and can be bent and folded arbitrarily.

[0025] Based on its excellent flexibility and transparency, the present invention also provides applications of the flexible organic room temperature phosphorescent material in the fields of afterglow imaging, information encryption and anti-counterfeiting, and X-ray development.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The organic room temperature phosphorescent material of the present invention has an extremely long phosphorescence lifetime (τ>50ms, τ max =543.9ms).

[0028] (2) The organic room temperature phosphorescent material of the present invention is prepared based on a polymer matrix and can be processed and folded into products of any shape because of its good flexibility.

[0029] (3) The phosphorescent molecules and polymer matrix required for the present invention are cheap and readily available, so the preparation cost of the organic room temperature phosphorescent material is relatively low.

[0030] (4) The preparation method of the present invention is simple, has low equipment requirements, and is easy to industrialize and produce on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 These are the steady-state fluorescence and phosphorescence spectra of the ultra-long organic room-temperature phosphorescent material prepared in Example 3.

[0032] Figure 2 This is the time-resolved emission decay of the ultra-long organic room temperature phosphorescent material prepared in Example 3.

[0033] Figure 3 This is a photo of the ultra-long organic room temperature phosphorescent material prepared in Example 3 folded into a thousand paper cranes.

[0034] Figure 4 These are transmission electron micrographs of the precursor solutions obtained after annealing in Examples 3-4, where (a) is Example 3 and (b) is Example 4.

[0035] Figure 5 These are optical electron microscope images of the ultra-long organic room temperature phosphorescent materials prepared in Examples 3-4, (a) is Example 3, and (b) is Example 4.

[0036] Figure 6This is a transmittance spectrum of the ultra-long organic room temperature phosphorescent material prepared in Example 3.

[0037] Figure 7 The flexible ultra-long afterglow organic room temperature phosphorescent material prepared in Example 3 is used for afterglow imaging and information encryption.

[0038] Figure 8 These are the steady-state fluorescence and phosphorescence spectra of the ultra-long organic room-temperature phosphorescent material prepared in Example 8.

[0039] Figure 9 These are the steady-state fluorescence and phosphorescence spectra of the ultra-long organic room-temperature phosphorescent material prepared in Example 9.

[0040] Figure 10 These are the steady-state fluorescence and phosphorescence spectra of the ultra-long organic room-temperature phosphorescent material prepared in Example 10. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0042] All raw materials used in the following embodiments were purchased commercially. Terpyridine, 2,3,5,6-tetrapyridyl-pyrazine, polyvinyl alcohol 1799, polyvinyl alcohol 1780, polyvinyl alcohol 1788, polyacrylamide, polyacrylic acid, polyacrylonitrile, and sodium polyacrylate were purchased from Aladdin. 4-terpyridine-4'-aniline and 4,4',4"-trimethyl-terpyridine were purchased from Bidler.

[0043] Example 1

[0044] (1) Add 1.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799) to 7 mL of deionized water, and heat and stir at 96°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0045] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0046] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0047] The resulting film material was tested for its photophysical properties and morphology. The film exhibited a bimodal fluorescence emission characteristic, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 389.2 ms, indicating an ultra-long-lifetime organic room-temperature phosphorescent material. Terpyridine molecules aggregated within the film to form granular structures approximately 3 μm in diameter.

[0048] Example 2

[0049] (1) 3.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A;

[0050] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0051] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0052] The resulting film material was tested for its photophysical properties and morphology. The film exhibited a bimodal fluorescence emission pattern, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 417.0 ms, demonstrating ultra-long-lifetime phosphorescence. Terpyridine molecules aggregated within the film to form granular structures approximately 3.5 μm in diameter.

[0053] Example 3

[0054] (1) Add 5.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799) to 7 mL of deionized water, and heat and stir at 95-105°C for 30-60 minutes until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0055] (2) annealing at 45-75°C for 15-30 minutes to obtain precursor solution B;

[0056] (3) Take 2 mL of precursor solution B and drop it onto a clean glass slide (25 mm × 75 mm) preheated at 45-75°C, and heat it at 45-75°C for 30-60 minutes to volatilize and form a film;

[0057] The obtained thin film material was tested for photophysical properties, morphology, etc. Figure 1 The steady-state fluorescence and phosphorescence spectra of the ultra-long organic room-temperature phosphorescent material prepared in Example 3 show that the fluorescence of the film has a double-peak emission characteristic, located at 350nm and 465nm, respectively, belonging to the monomer emission and the complex emission; Figure 2This is the time-resolved emission decay of the ultra-long organic room-temperature phosphorescent material prepared in Example 3. It can be seen that the phosphorescence emission is located at 485nm and the phosphorescence lifetime is 543.9ms, which is an ultra-long-lifetime phosphorescence;

[0058] like Figure 3 As shown, the organic room temperature phosphorescent material prepared in Example 3 has good flexibility and can be folded into the shape of a thousand paper cranes. At the same time, the organic room temperature phosphorescent material has an ideal afterglow duration of more than 2.5 seconds.

[0059] Figure 4 (a) is a transmission electron micrograph of precursor solution B obtained by annealing in this example. During the annealing process, terpyridine molecules self-assembled into uniform nanoparticles (approximately 2.5 nm in diameter);

[0060] Figure 5 (a) is an optical electron micrograph of the organic room-temperature phosphorescent material prepared in this example. It shows that the nanoparticles formed by terpyridine annealing further aggregate during the heating and volatilization process to form micron-sized aggregates. Terpyridine molecules aggregate in the film to form particles with a diameter of approximately 4 μm.

[0061] Figure 6 The transmittance spectrum of the organic room temperature phosphorescent material prepared in this example is shown. It can be seen that the obtained organic room temperature phosphorescent material has high transparency (90% transmittance);

[0062] Figure 7 The organic room temperature phosphorescent material prepared in this embodiment is used for afterglow imaging and information encryption. A photomask is placed on the prepared phosphorescent film material, and the room temperature phosphorescent film acts as an imaging screen, which can realize the imaging of a specific pattern under ultraviolet light.

[0063] Example 4

[0064] (1) 7.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799 degree of alcoholysis) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A;

[0065] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0066] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0067] The resulting film material was tested for photophysical properties and morphology. The film exhibited a bimodal fluorescence emission characteristic, with emission at 350 nm belonging to monomeric and complexed emission at 465 nm, respectively. The phosphorescence emission was located at 485 nm, with a lifetime of 489.6 ms, indicating an ultra-long lifetime.

[0068] Figure 4 (b) is a transmission electron micrograph of the precursor solution B obtained by annealing in this example. During the annealing process, the terpyridine molecules self-assembled into uniform nanoparticles (approximately 3.0 nm in diameter);

[0069] Figure 5 (b) is an optical electron micrograph of the organic room-temperature phosphorescent material prepared in this example. It shows that the nanoparticles formed by terpyridine annealing further aggregate during the heating and volatilization process to form micron-sized aggregates. Terpyridine molecules aggregate in the film to form particles with a diameter of approximately 5 μm.

[0070] Example 5

[0071] (1) 9.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C for 30-60 minutes until the solution became homogeneous and transparent to obtain precursor solution A;

[0072] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0073] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0074] The resulting film material was tested for its photophysical properties and morphology. The film exhibited a bimodal fluorescence emission pattern, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 489.6 ms, demonstrating ultra-long-lifetime phosphorescence. Terpyridine molecules aggregated within the film to form fibrous structures approximately 15 μm in width.

[0075] It can be seen from Examples 1-5 that as the amount of terpyridine added increases, the phosphorescence performance tends to first increase and then decrease, and the optimal terpyridine phosphor is 5.0 mg (1.0 wt %).

[0076] Example 6

[0077] (1) Add 5.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1788) to 7 mL of deionized water, and heat and stir at 80°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0078] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0079] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0080] The resulting film material was tested for photophysical properties and morphology. The film exhibited a bimodal fluorescence emission characteristic, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 135.4 ms, demonstrating ultra-long-lifetime phosphorescence. Compared to phosphorescent materials prepared using polyvinyl alcohol 1799, the reduced phosphorescence performance is attributed to the lower degree of alcoholysis of polyvinyl alcohol 1788, which fails to provide sufficient hydrogen bonds to form a rigid environment for crystallization and effectively limit vibrational energy dissipation in the phosphor.

[0081] Example 7

[0082] (1) Add 5.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1780) to 7 mL of deionized water, and heat and stir at 75°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0083] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0084] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0085] The resulting film material was tested for photophysical properties and morphology. The film exhibited a bimodal fluorescence emission pattern, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 123.9 ms, demonstrating ultra-long-lifetime phosphorescence. Compared to phosphorescent materials prepared using polyvinyl alcohol 1799 and 1788, the phosphorescence performance was further reduced due to the reduced degree of alcoholysis of polyvinyl alcohol 1780.

[0086] Example 8

[0087] (1) 5.0 mg of 4,4',4"-trimethyl-2,2':6',2"-terpyridine and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A.

[0088] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0089] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0090] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and found to have obvious phosphorescent emission characteristics. Figure 8 As shown, the main peak of the steady-state fluorescence emission of the organic room-temperature phosphorescent material is located at 469 nm, the main peak of the phosphorescence emission is located at about 492 nm, and the phosphorescence lifetime is 331.3 ms.

[0091] Example 9

[0092] (1) 5.0 mg of 2,3,5,6-tetra(pyridin-2-yl)pyrazine and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A.

[0093] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0094] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0095] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and found to have obvious phosphorescent emission characteristics. Figure 9 As shown, the main peak of the steady-state fluorescence emission of this organic room-temperature phosphorescent material is located at 461nm, the main peak of the phosphorescence emission is located at around 495nm, and the phosphorescence lifetime is 53.5ms. Due to the increase in the number of rotatable and vibrating chemical bonds in the molecular structure of 2,3,5,6-tetrapyridyl-pyrazine phosphor, energy dissipation is more severe, and triplet excitons are quenched, resulting in a shorter phosphorescence lifetime.

[0096] Example 10

[0097] (1) 5.0 mg of 4-terpyridyl-4'-aniline (4-([2,2':6',2"-terpyridin]-4'-yl)aniline) and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A.

[0098] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0099] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0100] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and found to have obvious phosphorescent emission characteristics. Figure 10 As shown, the main peak of the steady-state fluorescence emission of this organic room-temperature phosphorescent material is located at 452nm, the main peak of the phosphorescence emission is located around 498nm, and the phosphorescence lifetime is 45.1ms. Similarly, due to the increase in the number of rotatable and vibratory chemical bonds in the structure of the phosphor molecule 4-terpyridine-4'-aniline, energy dissipation is more severe, and triplet excitons are quenched, resulting in a shorter phosphorescence lifetime.

[0101] Example 11

[0102] (1) Add 5.0 mg of terpyridine and 500 mg of polyacrylic acid to 7 mL of deionized water, and heat and stir at 96°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0103] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0104] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0105] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and showed obvious phosphorescence emission characteristics. The main peak of the steady-state fluorescence emission of the organic room temperature phosphorescent material was located at 365nm, the main peak of the phosphorescence emission was located at about 475nm, and the phosphorescence lifetime was 240.3ms.

[0106] Example 12

[0107] (1) Add 5.0 mg of terpyridine and 500 mg of polyacrylamide to 7 mL of deionized water, and heat and stir at 96°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0108] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0109] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0110] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and showed obvious phosphorescence emission characteristics. The main peak of the steady-state fluorescence emission of the organic room temperature phosphorescent material was located at 405nm, the main peak of the phosphorescence emission was located at around 400nm, and the phosphorescence lifetime was 441.4ms.

[0111] Example 13

[0112] (1) Add 5.0 mg of terpyridine and 500 mg of polyacrylonitrile to 7 mL of chloroform and heat and stir at 25°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0113] (2) Take 2 mL of precursor solution A and apply it on a clean glass slide (25 mm × 75 mm) preheated at 50 °C, and heat it at 50 °C for 60 minutes to evaporate and form a film;

[0114] The ultra-long organic room temperature phosphorescent material prepared in this embodiment was tested and showed obvious phosphorescence emission characteristics. The main peak of the steady-state fluorescence emission of the organic room temperature phosphorescent material was located at 457nm, the main peak of the phosphorescence emission was located at about 480nm, and the phosphorescence lifetime was 102.8ms.

[0115] Comparative Example 1

[0116] (1) Add 5.0 mg of terpyridine and 500 mg of sodium polyacrylate to 7 mL of deionized water, and heat and stir at 96°C until the solution becomes homogeneous and transparent to obtain precursor solution A;

[0117] (2) Annealing at 65°C for 15 minutes to obtain precursor solution B;

[0118] (3) Take 2 mL of precursor solution B and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0119] Testing of the ultra-long organic room-temperature phosphorescent material produced in this example revealed that the film material exhibited no afterglow properties, with no observed afterglow after the excitation light source was removed. This is because sodium polyacrylate is unable to provide multiple hydrogen bonds, and the rigid environment restricts non-radiative energy dissipation in the phosphor, leading to triplet exciton quenching.

[0120] Comparing Examples 3, 12, and 13 with Comparative Example 1, it can be concluded that the rigid environment of the polymer matrix and the multiple hydrogen bonding provided are essential conditions for achieving long-life phosphorescence. The more rigid the polymer matrix and the more hydrogen bonds it provides, the longer the phosphorescence lifetime.

[0121] Comparative Example 2

[0122] (1) 1.0 mg of terpyridine and 500 mg of polyvinyl alcohol (1799) were added to 7 mL of deionized water and heated and stirred at 96°C until the solution became homogeneous and transparent to obtain precursor solution A;

[0123] (2) Take 2 mL of precursor solution A and apply it on a clean glass slide (25 mm × 75 mm) preheated at 65 °C, and heat it at 65 °C for 60 minutes to evaporate and form a film;

[0124] The resulting thin film material was tested for photophysical properties and morphology. The film exhibited a bimodal fluorescence emission characteristic, with emission peaks at 350 nm and 465 nm, representing monomeric and complexed emission, respectively. Phosphorescence emission was located at 485 nm, with a lifetime of 473.7 ms, indicating ultra-long phosphorescence lifetime. In the preparation process of this example, the precursor solution A lacked an annealing step. While the organic room-temperature phosphorescent material obtained by directly heating and volatilizing the precursor solution A still exhibited an ultra-long phosphorescence lifetime, the lifetime was reduced to 87.1% compared to that of Example 3 (which included an annealing step).

Claims

1. A method for preparing a flexible organic room temperature phosphorescent material, characterized in that: Including steps: A terpyridine phosphor and a polymer are dissolved in water to obtain a precursor solution, and the precursor solution is annealed and volatilized to form a film to obtain the flexible organic room temperature phosphorescent material; the polymer is polyvinyl alcohol; the amount of the terpyridine phosphor added is 0.2 to 1.8 wt% of the weight of the polymer; the transmittance of the flexible organic room temperature phosphorescent material is not less than 90%, and the phosphorescence lifetime is not less than 50 ms; The structure of the terpyridine phosphor is shown below: 。 2. The method for preparing a flexible organic room temperature phosphorescent material according to claim 1, wherein: The alcoholysis degree of the polyvinyl alcohol is not less than 70%.

3. The method for preparing the flexible organic room temperature phosphorescent material according to claim 1, wherein: The dissolution temperature is 25-105°C and the dissolution time is 2-60 minutes.

4. The method for preparing a flexible organic room temperature phosphorescent material according to claim 1, wherein: The annealing temperature is 40-75°C, and the annealing time is 15-30 minutes.

5. The method for preparing a flexible organic room temperature phosphorescent material according to claim 1, wherein: The temperature for volatilization and film formation is 50-75°C, and the time is 45-60 minutes.

6. The flexible organic room temperature phosphorescent material obtained by the preparation method according to any one of claims 1 to 5, characterized in that: The transmittance of the flexible organic room temperature phosphorescent material is not less than 90%, and the phosphorescence life is not less than 50ms.

7. Use of the flexible organic room temperature phosphorescent material according to claim 6 in the preparation of information encryption and anti-counterfeiting materials, afterglow imaging materials or X-ray development materials.

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