A kind of hot-activated triplet-triplet annihilation upconversion luminescent material and its preparation and application

Abstract

The application discloses a kind of triplet-triplet annihilation upconversion luminescent material based on thermal activation, preparation and application.Crystal violet, methylene blue or its derivative is applied as photosensitizer in triplet-triplet annihilation upconversion luminescent material for the first time, and a series of triplet-triplet annihilation upconversion materials are prepared, the energy barrier between photosensitizer and annihilator is overcome by the energy transfer process of endothermic triplet-triplet energy, effective TTA upconversion is realized, more possibilities are provided for the selection of TTA upconversion material, and the ion derivative 9,10-diphenyl anthracene-2-sodium sulfonate of annihilator is introduced, so that the DPA-SO3 ‑ The cationic photosensitizer forms ion pair by electrostatic attraction, and the DPA skeleton structure is also included, which can form intermolecular interaction with free DPA molecules, effectively shorten the distance between photosensitizer and annihilator, and make the photosensitizer doping more uniform, so as to further improve the efficiency of TTET and the quantum efficiency of TTA upconversion.

Description

Technical Field

[0001] This invention relates to the field of photon upconversion materials. More specifically, it relates to a thermally activated triplet-triplet annihilation upconversion luminescent material, its preparation, and its applications. Background Technology

[0002] As we all know, energy is the foundation for human survival and development, and solar energy is considered one of the most ideal energy sources due to its cleanliness and large reserves. Photon upconversion technology is a promising technology to improve the efficiency of solar energy utilization. It converts low-energy (long-wavelength) photons into high-energy (short-wavelength) photons to obtain anti-Stokes shift luminescence. Photon upconversion technology has great application prospects in fields such as solar cells, artificial photosynthesis, photocatalysis, and optoelectronic devices, and has attracted widespread attention in recent years. At present, there are four main technologies for realizing photon upconversion: (1) two / multi-photon upconversion; (2) rare-earth-doped nanomaterial upconversion; (3) nonlinear optical material upconversion; and (4) triplet-triplet annihilation upconversion (TTA). Compared with the first three upconversion technologies, TTA upconversion has advantages such as low excitation power density, tunable excitation and emission wavelengths, and high upconversion quantum efficiency.

[0003] The TTA upconversion system consists of two parts: a photosensitizer and an annihilator (or acceptor). The upconversion luminescence quantum efficiency (Φ) is... UC The efficiency of photophysics is affected by the quantum efficiency of four photophysical processes, namely the intersystem crossing efficiency (Φ). ISC Triplet-Triplet Energy Transfer Efficiency (Φ) TTET ), triplet-triplet annihilation efficiency (Φ TTA ) and the fluorescence quantum yield of the annihilator (Φ F ), can be calculated using the formula: Φ UC =Φ ISC Φ TTET Φ TTA Φ F .

[0004] To improve the quantum efficiency of TTA upconversion, significant efforts have been devoted to developing upconversion photosensitizers and annihilators. Among these, energy level matching between the photosensitizer and the annihilator is one of the greatest challenges. In traditional TTA upconversion systems, the triplet energy level of the photosensitizer (ΔE...) T (D) is slightly higher than the triplet energy level of the annihilator (ΔE). T(A) indicates that exothermic processes favor triplet energy transfer, while endothermic triplet sensitization processes are typically less efficient. However, a special upconversion system based on thermal activation has recently been reported (J. Phys. Chem. Lett. 2019, 10, 6239-6245. and J. Phys. Chem. Lett. 2020, 11, 318-324.). This study demonstrates a method that utilizes the low-energy-level photosensitizer PdTPTBP in combination with the high-energy-level annihilator DPA to overcome the 180 meV energy barrier in the TTET process, achieving a large anti-Stokes shift and highly efficient upconversion luminescence, with a peak efficiency of 195 mW / cm². 2 A solid-state upconversion quantum yield of over 5% was achieved under 635nm laser irradiation, expanding the selection range of TTA upconversion materials.

[0005] Although researchers have developed thermally activated energy transfer (TTA) upconversion systems, the most commonly used photosensitizers for TTA upconversion are currently cyclic metallized complexes of porphyrin or phthalocyanine derivatives coordinated with palladium, platinum, ruthenium, iridium, etc. These photosensitizers have problems such as difficult synthesis, high price, poor stability, and serious self-aggregation.

[0006] Therefore, developing a new combination of raw materials for preparing thermally activated triplet-triplet annihilation upconversion luminescent materials is of great importance for expanding the selection range of upconversion materials. Summary of the Invention

[0007] One objective of this invention is to provide a thermally activated triplet-triplet annihilation upconversion luminescent material. This material utilizes a photosensitizer with a lower triplet energy level in combination with an annihilator with a higher triplet energy level. The endothermic triplet-triplet energy transfer process overcomes the energy barrier between the photosensitizer and the annihilator, achieving a large anti-Stokes shift and efficient upconversion luminescence. The upconversion luminescence quantum efficiency is high, and the photosensitizer in the raw material has the advantages of low price and high sensitization efficiency.

[0008] Another objective of this invention is to provide a method for preparing the triplet-triplet annihilation upconversion luminescent material as described above.

[0009] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0010] This invention discloses a thermally activated triplet-triplet annihilation upconversion luminescent material, wherein the triplet-triplet annihilation upconversion luminescent material comprises a photosensitizer, an annihilation agent, and an ionic derivative of the annihilation agent; the photosensitizer has the structural formula shown in formula (I) or formula (II):

[0011]

[0012] Wherein, R1 and R2 may be the same or different; R1 and R2 each independently represent hydrogen, an unsubstituted alkyl group containing 1 to 10 carbon atoms, an unsubstituted cycloalkyl group containing 3 to 10 carbon atoms, an alkoxy group containing 1 to 10 carbon atoms, a phenylalkyl group, or a naphthylalkyl group; and X is a halogen.

[0013] This invention is the first to apply crystal violet (CV), methylene blue (MB), or their derivatives as photosensitizers to triplet-triplet annihilation upconversion luminescent materials, preparing a series of thermally activated triplet-triplet annihilation upconversion luminescent materials. These photosensitizers are commercially available, inexpensive, and free of noble metals and heavy atoms, exhibiting high sensitization efficiency. They can overcome the energy barrier in the TTET process through thermal activation energy provided by the annihilator DPA at room temperature, achieving effective TTA upconversion. This provides more possibilities for the selection of TTA upconversion materials and overcomes the problems of difficult synthesis, high cost, poor stability, and severe self-aggregation of commonly used photosensitizers in the existing field. Secondly, by introducing the ionic derivative of the annihilator, sodium 9,10-diphenylanthracene-2-sulfonate, the negatively charged DPA-SO3... - The ion pair is formed with the cationic photosensitizer through electrostatic attraction. At the same time, the ionic derivative of the annihilator contains the DPA backbone structure and can form intermolecular interactions with free DPA molecules, effectively bringing the photosensitizer and annihilator closer together, thereby further improving the TTET efficiency and the quantum efficiency of TTA upconversion.

[0014] In one specific embodiment, the present invention selects 9,10-diphenylanthracene (DPA), which has high fluorescence quantum efficiency and high triplet energy level, as the energy annihilation agent for TTA upconversion, and selects common dyes crystal violet or methylene blue as photosensitizers to prepare triplet-triplet annihilation upconversion luminescent materials. However, according to literature reports, the triplet energy levels of photosensitizers are as follows: CV has a triplet energy level of 1.69 eV (Source: Journal of the American Chemical Society 1942, 64, 1774.), MB has a triplet energy level of 1.39 eV (Source: Coordination Chemistry Reviews 2002, 233-234, 351.) or -1.50 eV (Source: Journal of the Chemical Society 1992, 88, 2329.), and the annihilation agent DPA has a triplet energy level of 1.77 eV, which is significantly higher than the triplet energy levels of the aforementioned photosensitizers. By using the thermal activation energy provided by room temperature, the energy barrier in the TTET process can be overcome, thereby preparing a triplet-triplet annihilation upconversion luminescent material with high quantum efficiency.

[0015] Furthermore, the unsubstituted alkyl group containing 1 to 10 carbon atoms is methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, or n-nonyl.

[0016] The unsubstituted cycloalkyl group containing 3 to 10 carbon atoms is cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or adamantane;

[0017] The structural formula of the alkoxy group containing 1 to 10 carbon atoms is -OR; wherein R represents methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, 1-ethoxyethyl, 2-(2-ethoxyethoxy)ethyl, 2-(2-methoxyethoxy)ethyl, 2-(2-(2-methoxyethoxy)ethoxy)ethyl or 2-(2-(2-ethoxyethoxy)ethoxy)ethyl;

[0018] The phenylalkyl group is phenylmethyl, benzyl, phenylpropyl, phenyl n-butyl, or phenyl n-pentyl;

[0019] The naphthylalkyl group is naphthylmethyl, naphthylethyl, naphthylpropyl, naphthyl-n-butyl, or naphthyl-n-pentyl;

[0020] The halogen is fluorine, chlorine, bromine or iodine.

[0021] Furthermore, the photosensitizer includes, but is not limited to, one of crystal violet, methylene blue, ethyl violet, or crystal violet lactone.

[0022] Furthermore, the annihilating agent is 9,10-diphenylanthracene.

[0023] Furthermore, the ionic derivative of the annihilator is sodium 9,10-diphenylanthracene-2-sulfonate.

[0024] In this invention, the triplet-triplet annihilation upconversion luminescent material is more uniformly doped by physically doping with an ionic derivative of the annihilator, and the distance between the photosensitizer and the annihilator is effectively shortened, thereby further improving the TTET efficiency and the quantum efficiency of TTA upconversion. The ionic derivative of the annihilator is selected from the anionic derivative of the annihilator: sodium 9,10-diphenylanthracene-2-sulfonate, and its molecular formula and synthesis process are as follows:

[0025]

[0026] The specific synthesis steps can be found in the reference (Angewandte Chemie 2015, 54, 11550):

[0027] 9,10-Diphenylanthracene, glacial acetic acid, and acetic anhydride were mixed, and fuming sulfuric acid was added dropwise under ice bath conditions. The mixture was then heated to reflux, cooled to room temperature, and sodium chloride was added and diluted with water. The reaction was then carried out at high temperature until complete, and then cooled to room temperature. Finally, the mixture was neutralized with sodium hydroxide, and post-treatment was performed to obtain yellow-green crystals.

[0028] Furthermore, the molar ratio of the photosensitizer, the ionic derivative of the annihilator, and the annihilator in the upconversion material is 1:1:1000 to 1:1:200000. Exemplarily, the molar ratio of the photosensitizer, the ionic derivative of the annihilator, and the annihilator is 1:1:1000 to 1:1:5000, 1:1:10000 to 1:1:10000, 1:1:10000 to 1:1:50000, 1:1:50000 to 1:1:100000, 1:1:100000 to 1:1:20000, 1:1:3000 to 1:1:50000, 1:1:10000 to 1:1:100000, 1:1:5000 to 1:1:200000. 1:1:20000~1:1:50000, 1:1:10000~1:1:150000, 1:1:50000~1:1:200000, 1:1:200000~1:1:200000, etc.

[0029] Furthermore, the triplet-triplet annihilation upconversion luminescent material achieves upconversion from green light to blue light under inert gas conditions.

[0030] Furthermore, the inert gas is high-purity argon or high-purity nitrogen.

[0031] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0032] This invention discloses a method for preparing the triplet-triplet annihilation upconversion luminescent material, which obtains the triplet-triplet annihilation upconversion luminescent material by physically doping a photosensitizer, an annihilator, and an ionic derivative of the annihilator.

[0033] Furthermore, the physical doping method is either co-crystallization or co-precipitation; wherein, the sample prepared by the co-crystallization method has a slow crystallization rate and a larger size; the upconversion microcrystal prepared by the co-precipitation method has a smaller size, more uniform doping, and higher upconversion quantum efficiency.

[0034] Furthermore, the co-crystallization method involves dissolving the photosensitizer, annihilator, and ionic derivative of the annihilator in an organic solvent S1 in a certain proportion, and then evaporating the organic solvent S1 to obtain the triplet-tript annihilation upconversion luminescent material of the present invention; wherein, the organic solvent S1 is selected from one or two of tetrahydrofuran, dioxane, dichloromethane, chloroform, methanol, ethanol, toluene, etc.

[0035] Furthermore, the co-precipitation method involves dissolving the photosensitizer, annihilator, and ionic derivative of the annihilator in a proportionate solution in a good solvent S2, and then injecting the solution into a poor solvent S3 under vigorous stirring to allow crystals to gradually precipitate. The mixture is then centrifuged and dried to obtain the triplet-trittt annihilation upconversion luminescent material of this invention. The good solvent S2 is one or two of tetrahydrofuran, dioxane, ethyl acetate, dichloromethane, chloroform, toluene, xylene, etc., and the poor solvent S3 is n-hexane, n-heptane, petroleum ether, etc., which are miscible with the good solvent S2.

[0036] Furthermore, the stirring rate during the vigorous stirring is >600 rpm.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention discloses a thermally activated triplet-triplet annihilation upconversion luminescent material, its preparation, and its application. In this invention, a series of thermally activated triplet-triplet annihilation upconversion luminescent materials were prepared using pure organic dyes, crystal violet, methylene blue, or their derivatives, which are free of precious metals and heavy atoms, as photosensitizers and DPA, which has a high triplet energy level, as annihilation agents. These materials overcome the energy barrier between the photosensitizer and the annihilator through an endothermic triplet-triplet energy transfer process, achieving efficient TTA upconversion. The photosensitizers used are inexpensive and highly stable, providing more possibilities for the selection of TTA upconversion materials. Secondly, the ionic derivative of the annihilator, sodium 9,10-diphenylanthracene-2-sulfonate, essentially retains the photophysical properties of DPA, allowing its negative charge to electrostatically attract the cationic photosensitizer to form ion pairs. Simultaneously, its DPA framework structure allows for intermolecular interactions with free DPA molecules, effectively bridging the gap between the photosensitizer and the annihilator, thereby further improving TTET efficiency and the quantum efficiency of TTA upconversion. This method facilitates more uniform doping of photosensitizers and annihilators, and its preparation method is simple and easy to process, providing a foundation for the application of triplet-triplet annihilation upconversion luminescent materials in real life. Attached Figure Description

[0039] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] Figure 1 The sodium 9,10-diphenylanthracene-2-sulfonate prepared in Example 1 is shown. 1 1H NMR (400MHz) spectrum.

[0041] Figure 2The absorption and emission spectra of CV, MB, sodium 9,10-diphenylanthracene-2-sulfonate and DPA are shown.

[0042] Figure 3 The XRD patterns of the triplet-triplet annihilation upconversion luminescent material prepared in Example 2 with different addition amounts are shown.

[0043] Figure 4 The upconversion emission spectra of the samples prepared in Example 2 and Comparative Example 1 after being excited by a 532 nm laser at different excitation power densities are shown.

[0044] Among them, (a) and (c) are upconversion emission spectra under different excitation light power densities, and (b) and (d) are comparison diagrams of upconversion emission intensity under different excitation light power densities.

[0045] Figure 5 A scanning electron microscope image of the triplet-triplet annihilation upconversion luminescent material prepared in Example 3 is shown.

[0046] Figure 6 The upconversion emission spectra of the triplet-triplet annihilation upconversion luminescent material prepared in Example 3 are shown at different excitation power densities after being excited by a 532 nm laser.

[0047] Figure 7 The upconversion luminescence quantum efficiency diagrams of the triplet-triplet annihilation upconversion luminescent material prepared in Example 3, after being excited by a 532 nm laser, are shown at different excitation power densities.

[0048] Figure 8 An Arrhenius plot of the temperature-dependent TTET rate constant of the triplet-triplet annihilation upconversion luminescent material prepared in Comparative Example 1 is shown.

[0049] Figure 9 This demonstrates the application of the triplet-triplet annihilation upconversion luminescent material prepared in Example 3 in anti-counterfeiting. Detailed Implementation

[0050] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and figures, further explains the invention. Those skilled in the art should understand that the specific description below is illustrative and not restrictive, and should not be construed as limiting the scope of protection of the present invention. Any range described in the present invention includes endpoints, any values ​​between endpoints, and any sub-ranges formed by endpoints or any values ​​between endpoints.

[0051] In this invention, the preparation methods are all conventional unless otherwise specified. All raw materials used are available from publicly available commercial sources unless otherwise specified, and all percentages are by mass unless otherwise specified.

[0052] Example 1

[0053] This embodiment provides a method for preparing sodium 9,10-diphenylanthracene-2-sulfonate, the specific steps of which are as follows:

[0054] Weigh 1.0 g (3.03 mmol) of powdered DPA into a flask, then add a mixed solvent of glacial acetic acid (3.5 mL) and acetic anhydride (0.4 mL), and place in an ice bath. Then, add 60% fuming sulfuric acid dropwise, and reflux for 1 h after each addition. Cool the mixture to room temperature, add 1.7 g of NaCl, dilute with 15 mL of deionized water, and then react at 130 °C for 1 h. Cool the reaction solution to room temperature, neutralize with 5% NaOH, and then filter. Dissolve the obtained solid in ethanol, precipitate in water, and obtain a yellow-green precipitate. Recrystallize the obtained solid from ethanol to obtain the green product. The reaction yielded 0.4 g of yellow-green crystals, with a yield of approximately 31%. The structure was identified by 1H NMR spectroscopy; the NMR spectrum is shown below. Figure 1 The target compound was successfully prepared. The ¹H NMR spectra (400 MHz, methanol-d⁴) were: δ = 8.26 (s, ¹H), 7.64 (td, J = 16.5, 15.9, 6.9 Hz, ¹¹H), 7.45 (d, J = 12.7 Hz, 4H), and 7.40–7.33 (m, 2H) ppm.

[0055] First, the fundamental photophysical properties of the target compound were studied using steady-state absorption and emission spectra, such as... Figure 2 As shown. The photosensitizer CV exhibits strong absorption in the 460–640 nm range, with a maximum absorption peak at 580 nm. Under deoxygenated conditions, CV shows a maximum emission peak at approximately 665 nm. The photosensitizer MB has a strong absorption peak in the 520–720 nm range, with weaker absorption between 360 and 520 nm. Simultaneously, at the same concentration, the molar extinction coefficient of MB is significantly higher than that of CV (all extinction coefficients are calculated based on maximum absorption). MB shows maximum emission at 628 nm under both deoxygenated and non-deoxygenated conditions. The annihilator DPA exhibits four absorption peaks in DMF solution, located at 338 nm, 356 nm, 375 nm, and 395 nm. Under 375 nm light excitation, its emission spectrum was obtained, with the emission peak located between 415–435 nm. E S (A) = 3.10 eV. Ionic compound DPA-SO3 - Na +It basically retains the photophysical properties of DPA.

[0056] Example 2

[0057] CV / DPA triplet-tript annihilation upconversion luminescent materials with different addition amounts were prepared by co-crystallization, including the following steps:

[0058] 66 mg of DPA was dissolved in 2.5 mL of THF, and various proportions of crystal violet and sodium 9,10-diphenylanthracene-2-sulfonate were added, with the molar ratio of photosensitizer to annihilator being 1 / 1000, 1 / 5000, 1 / 10000, 1 / 20000, 1 / 50000, and 1 / 100000, respectively. The mixture was stirred thoroughly for 1 minute and sonicated at room temperature for 30 minutes to ensure homogeneity. The homogeneous solution was then slowly evaporated in a vacuum drying oven to obtain a triplet-triplet annihilation upconversion luminescent material.

[0059] MB / DPA triplet-tript annihilation upconversion luminescent materials with different addition amounts were prepared by co-crystallization, including the following steps:

[0060] 66 mg of DPA was dissolved in 2.5 mL of THF, and various proportions of methylene blue and sodium 9,10-diphenylanthracene-2-sulfonate were added, with the molar ratio of photosensitizer to annihilator being 1 / 1000, 1 / 5000, 1 / 10000, 1 / 20000, 1 / 50000, and 1 / 100000, respectively. The mixture was stirred thoroughly for 1 minute and then sonicated at room temperature for 30 minutes to ensure homogeneity. The homogeneous solution was then slowly evaporated in a vacuum drying oven to obtain a triplet-triplet annihilation upconversion luminescent material.

[0061] Figure 3 The XRD patterns of the triplet-triplet annihilation upconversion luminescent material prepared in this embodiment at different addition amounts are shown, compared with the raw materials DPA, CV, and MB. Figure 3 It is known that these doped upconversion samples are crystalline and have the same arrangement structure as DPA polycrystalline samples prepared by the same method, indicating that the influence of small amounts of photosensitizer and ion doping on the DPA structure is negligible.

[0062] Example 3

[0063] CV / DPA@DPA-SO3 with different addition amounts was prepared by coprecipitation method. - Triple-state annihilation upconversion luminescent materials include the following steps:

[0064] 66 mg of DPA was dissolved in 1.5 mL of THF, and various proportions of crystal violet and sodium 9,10-diphenylanthracene-2-sulfonate (equal in amount to the photosensitizer) were added, with the molar ratio of photosensitizer to annihilator being 1 / 5000, 1 / 10000, and 1 / 20000, respectively. The mixture was then injected into 4 mL of n-hexane at 1000 rpm with rapid stirring at room temperature for 2 minutes, followed by standing for 2 hours. After centrifugation at 8000 rpm for 5 minutes, the solid was dried in a vacuum drying oven to obtain dried upconversion microcrystalline material.

[0065] MB / DPA@DPA-SO3 with different addition amounts was prepared by coprecipitation method. - Triple-state annihilation upconversion luminescent materials include the following steps:

[0066] 66 mg of DPA was dissolved in 1.5 mL of THF, and various proportions of methylene blue and sodium 9,10-diphenylanthracene-2-sulfonate were added, with the same amount as the photosensitizer. The molar ratio of photosensitizer to annihilator was 1 / 5000, 1 / 10000, and 1 / 20000, respectively. The mixture was then injected into 4 mL of n-hexane at 1000 rpm with rapid stirring at room temperature for 2 minutes, followed by standing for 2 hours. After centrifugation at 8000 rpm for 5 minutes, the solid was dried in a vacuum drying oven to obtain the dried upconversion luminescent material. Figure 5 Figure 6 shows a scanning electron microscope (SEM) image of the upconversion luminescent material prepared in this embodiment, indicating that the annihilators of these photosensitizers form octahedral microcrystals with a size of several to tens of micrometers. Figure 6 shows the upconversion luminescence spectra of the upconversion luminescent material after excitation with a 532 nm laser at different excitation light power densities. Figure 6 It can be seen that as the excitation light power density increases, the upconversion luminescence intensity gradually increases. Figure 7 The upconversion luminescence quantum efficiency diagrams for the luminescent material excited by a 532 nm laser at different excitation power densities show that when CV / DPA is 1 / 10000, the efficiency increases with increasing excitation power density from 135 mW / cm². 2 Increased to 2.2 W / cm 2 The intensity of upconversion luminescence gradually increases. Simultaneously, the quantum efficiency of upconversion luminescence also gradually increases and tends to stabilize, with a maximum Φ... UC It reached approximately 0.3%.

[0067] Comparative Example 1

[0068] The experimental procedures were the same as in Example 2, except that the ion derivative 9,10-diphenylanthracene-2-sulfonate sodium was not added; all other experimental conditions were the same as in Example 2. Comparative samples from Example 2 and Comparative Example 1 were compared, such as... Figure 4 As shown, the upconversion luminescence intensity of the sample without sodium 9,10-diphenylanthracene-2-sulfonate is significantly lower than that of the sample doped with sodium 9,10-diphenylanthracene-2-sulfonate. This indicates that the ionic compound sodium 9,10-diphenylanthracene-2-sulfonate is crucial for improving the quantum efficiency of triplet-triplet annihilation upconversion.

[0069] To further determine the relationship between the energy transfer rate constant and temperature change, the natural logarithm of the energy transfer rate constant, lnk, was used. TTET Using temperature as the ordinate, plot the temperature against the Boltzmann (k) curve. B Plot the reciprocal of the product on the x-axis, see [reference]. Figure 8 As shown, according to the Arrhenius formula lnk TTET =lnA-ΔE T / k B T(where A is the exponential factor, k) B (where is the Boltzmann constant), a straight line was fitted using data from 298K to 218K, and the TTET activation energy (ΔE) from CV to DPA was obtained from the absolute value of the slope of the line. T The activation energy of TTET, calculated based on experimental results, is 0.078 eV. This is in contrast to the triplet energy gap ΔE reported in the literature between the photosensitizer CV and the annihilator DPA. T (0.08eV) consistent with the data, further confirming that the TTET process in the DPA / CV upconversion system is thermally activated.

[0070] Test case

[0071] Because the prepared upconversion luminescent material has good air resistance and stable upconversion characteristics, it was used for information encryption and multi-layer anti-counterfeiting displays. Templates were mass-produced using a laser engraving machine and divided into different areas, such as... Figure 9 As shown. Regions 1-4 were filled with pure DPA sample without photosensitizer, and the remaining areas were filled with DPA / CV@DPA-SO. 3- Samples. Under natural light, analog digits "88" and rounded rectangular clusters were obtained; these patterns emitted bright blue light under ultraviolet light. However, under 532nm green light excitation, only a clear blue "39" and a dolphin could be observed through a 470nm filter, demonstrating the great potential of these upconversion microcrystals in information encryption and anti-counterfeiting security applications. The shaded areas represent the blue upconversion luminescence.

[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A thermally activated triplet-triplet annihilation upconversion luminescent material, characterized in that, The triplet-triplet annihilation upconversion luminescent material comprises a photosensitizer, an annihilator and an ionic derivative of the annihilator; the photosensitizer comprises one of crystal violet, methylene blue, ethyl violet or crystal violet lactone; The annihilator is 9,10-diphenyl anthracene; The ionic derivative of the annihilator is sodium 9,10-diphenyl anthracene-2-sulfonate.

2. The triplet-triplet annihilation upconversion luminescent material of claim 1, wherein, The molar ratio of the photosensitizer, the ionic derivative of the annihilator and the annihilator in the triplet-triplet annihilation upconversion luminescent material is 1:1:1000-1:1:200000.

3. The triplet-triplet annihilation upconversion luminescent material of claim 1, wherein, The triplet-triplet annihilation upconversion luminescent material realizes upconversion from green light to blue light under inert gas condition.

4. The triplet-triplet annihilation upconversion luminescent material of claim 3, wherein, The inert gas is high-purity argon or high-purity nitrogen.

5. A method for preparing the triplet-triplet annihilation upconversion luminescent material according to any one of claims 1 to 4, characterized in that, The triplet-triplet annihilation upconversion luminescent material is obtained by physical doping of the photosensitizer, the annihilator and the ionic derivative of the annihilator.

6. The production method according to claim 5, wherein The physical doping method is a co-crystallization method or a co-precipitation method.

7. Use of the triplet-triplet annihilation upconversion luminescent material according to any one of claims 1-4 in the production of anti-counterfeiting products.

Images