A multi-wavelength hot-band excitation tta up-conversion doped microcrystal and application thereof

Abstract

The application discloses a kind of multi-wavelength hot band excitation TTA-UC up-conversion system and its application, wherein photosensitizer is platinum (II) octaethylporphyrin (PtOEP), and light emitting agent is 9,10-diphenylanthracene (DPA).The creativity of the application is that it breaks through the technical prejudice that photosensitizer PtOEP can only be excited at its ground state zero vibration level (i.e.532 nm) according to the existing technology, discloses that the photosensitizer (PtOEP) can also be excited at a series of hot band vibration levels (such as 589 nm, 635 nm, 655 nm and 671 nm) of its ground state, and opens up a new method of multi-wavelength hot band excitation up-conversion doped microcrystal (not quenched by oxygen in the air).It has potential practical value in multiple optical anti-counterfeiting and information multiple encryption.

Description

Technical Field

[0001] This invention relates to the field of weak light upconversion, specifically to a novel method for doped microcrystals based on triplet-triplet annihilation (TTA) upconversion using multi-wavelength tropical excitation and its application. Background Technology

[0002] Photon upconversion refers to the process of obtaining short-wavelength (high-energy) light from long-wavelength (low-energy) light. Currently, there are two main types of photon upconversion based on organic materials: strong two-photon absorption upconversion (TPA-UC) and triplet-triplet annihilation upconversion (TTA-UC). TPA-UC requires intense light at intensity levels of gigawatts to megawatts per square centimeter (GM to MW × cm²). -2 This upconversion technique, known as strong-light upconversion, is achieved under excitation by a very high intensity of excitation light, which limits its effective application. However, its advantage lies in the large anti-Stokes shift of the resulting photons. TTA-UC, on the other hand, requires weak light (W~mW×cm²) to achieve upconversion. -2 This process, known as weak upconversion, is achieved under excitation. Clearly, this weak upconversion technology has greater application value in fields such as solar photovoltaics, photocatalysis, biomedicine, light-controlled lighting, and environmental monitoring. However, its drawback is that the anti-Stokes shift of the obtained photon upconversion is relatively small.

[0003] This invention discloses a novel method for doped microcrystals based on multi-wavelength tropical excitation triplet-triplet annihilation upconversion. This method utilizes the activation of the ground-state thermal vibrational energy level of the photosensitizer PtOEP to obtain photon upconversion. It combines the advantages of the aforementioned two upconversion methods (TPA-UC and TTA-UC): namely, obtaining a large anti-Stokes shift upconversion under weak light field excitation, demonstrating significant innovation. The multi-wavelength tropical excitation upconversion system involved in this invention consists of a photosensitizer (platinum(II)octaethylporphyrin, abbreviated as PtOEP) and a luminescent agent (9,10-diphenylanthracene, abbreviated as DPA). Semiconductor lasers with wavelengths of 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm (peak power <1 W × cm⁻¹) are used respectively. -2Irradiation of the photosensitizer / luminescent agent binary system yielded upconversion blue light in both solution and solid microcrystals. The maximum anti-Stokes shift obtained in solution reached 1.04 eV, while the maximum anti-Stokes shift in solid microcrystals reached 0.95 eV. The inventiveness of this invention lies in overcoming the existing technical bias that the photosensitizer PtOEP can only be excited at its ground state zero vibrational energy level (i.e., 532 nm). It discloses that this photosensitizer can be excited at a series of tropical vibrational energy levels in its ground state (such as 589 nm, 635 nm, 655 nm, and 671 nm), pioneering a new method for multi-wavelength tropical excitation upconversion and solid-state upconversion unaffected by oxygen. It is worth emphasizing that the TTA-UC in the microcrystals differs from that in the solution state; the former does not require deoxygenation and can achieve upconversion in an air atmosphere, with stable luminescence intensity, possessing potential practical value in information multi-level encryption. Summary of the Invention

[0004] This invention discloses for the first time a platinum(II) octaethylporphyrin (PtOEP) / 9,10-diphenylanthracene (DPA) solution, which can obtain multi-wavelength tropical excited triplet-triplet annihilation upconversion luminescence under light excitation at different wavelengths (such as 532 nm, 589 nm, 635 nm, 655 nm, 671 nm), which has application value in the fields of anti-counterfeiting and biodetection.

[0005] The present invention adopts the following technical solution:

[0006] A multi-wavelength tropical-excited TTA upconversion solution system includes a platinum photosensitizer and 9,10-diphenylanthracene as luminescent agents; the solvent is chloroform, DMSO, or DMF, etc.; the platinum photosensitizer is platinum(II) octaethylporphyrin; the molar ratio of photosensitizer to luminescent agent is 1:20 to 2500. Preferably, when the platinum photosensitizer is platinum(II) octaethylporphyrin, the molar ratio of photosensitizer to luminescent agent is 1:28 to 1400; the photosensitizer concentration is 1 mM to 50 mM. The platinum photosensitizer, 9,10-diphenylanthracene luminescent agent, and solvent are mixed to obtain the multi-wavelength tropical-excited TTA-UC upconversion solution system.

[0007] A multi-wavelength tropical-excited TTA upconversion doped microcrystal is composed of a platinum photosensitizer and a 9,10-diphenylanthracene luminescent agent. The platinum photosensitizer is platinum(II) octaethylporphyrin; the molar ratio of photosensitizer to luminescent agent is 1:1000 to 100000. The platinum photosensitizer and 9,10-diphenylanthracene luminescent agent are precipitated in solution and then dried to obtain a multi-wavelength tropical-excited TTA upconversion solid microcrystal powder.

[0008] This invention discloses the preparation and application of multi-wavelength tropical excited TTA upconversion solid microcrystalline powder. The multi-wavelength tropical excited TTA upconversion material is a red-to-blue, yellow-to-blue, or green-to-blue upconversion material, and the excitation wavelength is 532 nm to 671 nm.

[0009] This invention discloses the application of the above-mentioned multi-wavelength tropical excitation TTA upconversion system in anti-counterfeiting multi-information encryption; when applied to anti-counterfeiting multi-information encryption, deoxygenation is not required.

[0010] This invention discloses a method for multi-wavelength tropical excitation upconversion. Specifically, upconversion blue light can be obtained by irradiating a photosensitizer / luminescent agent solution or doped microcrystals with multi-wavelength tropical excitation, thereby realizing multi-wavelength tropical excitation upconversion.

[0011] The solution system prepared in this invention comprises a photosensitizer (PtOEP), a luminescent agent (DPA), and a solvent (such as chloroform). When this system is placed in a cuvette and irradiated with excitation light at 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm (oxygen-free), green-to-blue, yellow-to-blue, or red-to-blue upconversion emissions (430 nm) are obtained, respectively, with a maximum anti-Stokes shift of 1.04 eV in solution. Existing techniques for platinum(II) octaethylporphyrin only yield green-to-blue upconversion emissions under 532 nm excitation light (oxygen-free), and there are no reports of irradiation with other wavelengths.

[0012] The solid microcrystalline powder prepared by this invention contains PtOEP (photosensitizer) and DPA (luminescent agent), which are added to a tetrahydrofuran / water (20 ml / 100 ml, 1 / 5) mixed solvent and then centrifuged and dried to obtain the microcrystalline powder. Under excitation light at 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm, respectively, green-to-blue, yellow-to-blue, and red-to-blue upconversion emission can be obtained, with a maximum anti-Stokes shift of 0.95 eV in the solid state.

[0013] In this invention, the excitation light for the upconversion solution system or the doped microcrystalline solid is generated using a conventional semiconductor laser, with an excitation light intensity ranging from 0.02 to 3.1 W / cm². 2 .

[0014] In this invention, in the multi-wavelength tropical excitation upconversion solution system, the molar ratio of PtOEP to DPA is 1:(28-1400), preferably 1:28; the PtOEP concentration is 1mM-50mM, preferably 50mM. In the multi-wavelength tropical excitation upconversion solid system, the molar ratio of PtOEP to DPA is 1:(1000-100000), preferably 1:12000. Under excitation at 532nm, 589nm, 635nm, 655nm, and 671nm (oxygen isolated), the PtOEP / DPA chloroform solution emits a blue upconversion at 430nm, with a maximum anti-Stokes shift of 1.04 eV. Under excitation at 532nm, 589nm, 635nm, 655nm, and 671nm, the PtOEP / DPA solid microcrystals emit a blue upconversion at 443nm, with a maximum anti-Stokes shift of 0.95 eV.

[0015] The inventiveness of this invention lies in overcoming the existing technical bias that the photosensitizer PtOEP can only be excited at its ground-state zero vibrational energy level (i.e., 532 nm). It discloses that the photosensitizer can be excited at a series of tropical vibrational energy levels in its ground state (such as 589 nm, 635 nm, 655 nm, and 671 nm), pioneering a new method for multi-wavelength tropical excitation upconversion and solid-state upconversion unaffected by oxygen. This has potential practical value in multi-layered optical anti-counterfeiting and multi-layered information encryption.

[0016] The inventiveness of this invention lies in the first disclosure that a photosensitizer (platinum(II)octaethylporphyrin) can excite upconversion materials with multi-wavelength lasers, overcoming the technical bias of the prior art that the photosensitizer can only excite upconversion materials at the ground state zero vibrational energy level (i.e., a single wavelength). Attached Figure Description

[0017] Figure 1 shows the absorption and emission spectra of PtOEP (10 mM) and DPA (10 mM) (solvent: chloroform).

[0018] Figure 2 shows the relationship between the upconversion spectral intensity and the excitation power density of the binary system of PtOEP / DPA solution (degassed chloroform) under 532 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA concentration is 50 µM / 1.4 mM).

[0019] Figure 3 shows the relationship between the upconversion spectral intensity and the excitation power density of the binary system of PtOEP / DPA solution (degassed chloroform) under 589 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA concentration is 50 µM / 1.4 mM).

[0020] Figure 4 shows the relationship between the upconversion spectral intensity and the excitation power density of the binary system of PtOEP / DPA solution (degassed chloroform) under 635 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA concentration is 50 µM / 1.4 mM).

[0021] Figure 5 shows the relationship between the upconversion spectral intensity and the excitation power density of the binary system of PtOEP / DPA solution (degassed chloroform) under 655 nm excitation (left) and the corresponding plot of the logarithm of the upconversion integral and the logarithm of the power density (right) (PtOEP / DPA concentration is 50 µM / 1.4 mM).

[0022] Figure 6 shows the relationship between the upconversion spectral intensity and the excitation power density of the binary system of PtOEP / DPA solution (degassed chloroform) under 671 nm excitation (left) and the corresponding plot of the logarithm of the upconversion integral and the logarithm of the power density (right) (PtOEP / DPA concentration is 50 µM / 1.4 mM).

[0023] Figure 7 shows the upconversion spectra of binary systems of PtOEP / DPA solutions (degassed chloroform) with different concentration ratios under 589 nm excitation (DPA concentration is 1.4 mM).

[0024] Figure 8 shows the upconversion spectra of binary systems of PtOEP / DPA solutions (degassed chloroform) with different concentration ratios under 635 nm excitation (DPA concentration is 1.4 mM).

[0025] Figure 9 shows the upconversion spectra of binary systems of PtOEP / DPA solutions (degassed chloroform) with different concentration ratios under 655 nm excitation (DPA concentration is 1.4 mM).

[0026] Figure 10 is a histogram of the size distribution of PtOEP / DPA microcrystals, with a ratio of photosensitizer to luminescent agent of 1:1000.

[0027] Figure 11 is a histogram of the size distribution of PtOEP / DPA microcrystals, with a ratio of photosensitizer to luminescent agent of 1:6000.

[0028] Figure 12 is a histogram of the size distribution of PtOEP / DPA microcrystals, with a ratio of photosensitizer to luminescent agent of 1:12000.

[0029] Figure 13 is a histogram of the size distribution of PtOEP / DPA microcrystals, with a ratio of photosensitizer to luminescent agent of 1:13000.

[0030] Figure 14 shows the XRD spectra of PtOEP / DPA and DPA microcrystals, with a photosensitizer to luminescent agent ratio of 1:1000.

[0031] Figure 15 shows the XRD spectra of PtOEP / DPA and DPA microcrystals, with a photosensitizer to luminescent agent ratio of 1:6000.

[0032] Figure 16 shows the XRD spectra of PtOEP / DPA and DPA microcrystals, with a photosensitizer to luminescent agent ratio of 1:12000.

[0033] Figure 17 shows the XRD spectra of PtOEP / DPA and DPA microcrystals, with a photosensitizer to luminescent agent ratio of 1:13000.

[0034] Figure 18 shows the upconversion spectra of binary PtOEP / DPA microcrystals with different doping ratios under 532 nm excitation.

[0035] Figure 19 shows the upconversion spectra of binary PtOEP / DPA microcrystals with different doping ratios under 589 nm excitation.

[0036] Figure 20 shows the upconversion spectra of binary PtOEP / DPA microcrystals with different doping ratios under 635 nm excitation.

[0037] Figure 21 shows the upconversion spectra of binary PtOEP / DPA microcrystals with different doping ratios under 655 nm excitation.

[0038] Figure 22 shows the relationship between the upconversion spectral intensity and the excitation power density of the PtOEP / DPA solid (in air) binary system under 532 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0039] Figure 23 shows the relationship between the upconversion spectral intensity and the excitation power density of the PtOEP / DPA solid (in air) binary system under 589 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0040] Figure 24 shows the relationship between the upconversion spectral intensity and the excitation power density of the PtOEP / DPA solid (in air) binary system under 635 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0041] Figure 25 shows the relationship between the upconversion spectral intensity and the excitation power density of the PtOEP / DPA solid (in air) binary system under 655 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0042] Figure 26 shows the relationship between the upconversion spectral intensity and the excitation power density of the PtOEP / DPA solid (in air) binary system under 671 nm excitation (left) and the corresponding logarithm of the upconversion integral versus the logarithm of the power density (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0043] Figure 27 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 532 nm excitation (PtOEP / DPA molar ratio is 1 / 1000).

[0044] Figure 28 shows the relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 589 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 1000).

[0045] Figure 29 shows the relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 635 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 1000).

[0046] Figure 30 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 655 nm excitation (PtOEP / DPA molar ratio is 1 / 1000).

[0047] Figure 31 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 532 nm excitation (PtOEP / DPA molar ratio is 1 / 6000).

[0048] Figure 32 shows the relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 589 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 6000).

[0049] Figure 33The relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 635 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 6000).

[0050] Figure 34 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 655 nm excitation (PtOEP / DPA molar ratio is 1 / 6000).

[0051] Figure 35 shows the relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 532 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0052] Figure 36 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 589 nm excitation (PtOEP / DPA molar ratio is 1 / 12000).

[0053] Figure 37 shows the relationship between the upconversion spectral intensity and time of the PtOEP / DPA solid (in air) binary system under 635 nm excitation (left) and the corresponding change in upconversion intensity (right) (PtOEP / DPA molar ratio is 1 / 12000).

[0054] Figure 38 shows the relationship between the upconversion spectral intensity and time (left) and the corresponding change in upconversion intensity (right) of the PtOEP / DPA solid (in air) binary system under 655 nm excitation (PtOEP / DPA molar ratio is 1 / 12000).

[0055] Figure 39 This is a schematic diagram illustrating the application of PtOEP / DPA solid microcrystalline encryption and anti-counterfeiting technology in an air atmosphere.

[0056] Figure 40 shows the absorption and emission spectra of PtOEP (10 mM) and 9,10-bis(p-methoxyphenyl)anthracene (DMOPA, 10 mM) (solvent: DMF).

[0057] Figure 41 shows the upconversion spectrum of PtOEP / DMOPA (degassed DMF solution) under 532 nm excitation (PtOEP / DMOPA concentration ratio: 50 µM / 1.4 mM).

[0058] Figure 42 shows the upconversion spectrum of PtOEP / DMOPA (degassed DMF solution) under 589 nm excitation (PtOEP / DMOPA (degassed DMF solution) concentration was 50 µM / 1.4 mM).

[0059] Figure 43 shows the absorption and emission spectra of PtOEP (10 mM) and 9,10-bis(butoxy)anthracene (DBOPA, 10 mM) (solvent: DMF).

[0060] Figure 44 shows the upconversion spectrum of PtOEP / DBOPA (degassed DMF) under 532 nm excitation (PtOEP / DBOPA concentration of 50 µM / 1.4 mM).

[0061] Figure 45 shows the upconversion spectrum of PtOEP / DBOPA (degassed DMF) under 589 nm excitation (PtOEP / DBOPA concentration of 50 µM / 1.4 mM). Detailed Implementation

[0062] This invention discloses a multi-wavelength tropical-excited TTA upconversion solution system (PtOEP / DPA and solvent) and a doped microcrystalline solid (PtOEP / DPA). This invention also discloses its application in multi-wavelength tropical-excited upconversion microcrystalline materials. The invention is further described below with reference to the accompanying drawings and embodiments.

[0063] The ultraviolet-visible absorption spectra were measured using a SHIMADZU UV2600 ultraviolet spectrophotometer; fluorescence spectra were measured using an Edinburgh FLS-920 fluorescence spectrometer. Upconversion spectroscopy was performed using semiconductor lasers at 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm as the light source (excitation light intensity ranging from 0.02 to 3.1 W / cm²). 2 Unless otherwise specified, select 0.968W / cm 2 The test was conducted using a PR655 spectrometer, and the spectra were recorded.

[0064] The raw materials used in this invention are all commercially available products, and the specific preparation and testing methods are all conventional techniques; unless otherwise specified, all operations are carried out at room temperature.

[0065] In this invention, the chemical structural formulas of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) are as follows:

[0066]

[0067] Example 1: A photosensitizer and a luminescent agent were added to chloroform to obtain a multi-wavelength tropical excitation upconversion solution system.

[0068] The preparation method of the multi-wavelength tropical excitation upconversion solution system (photosensitizer / luminescent agent) is as follows: the concentration ratio of photosensitizer PtOEP / luminescent agent DPA is 1:28 (mol: mol) (specifically, the concentration of photosensitizer is 50 mM and the concentration of luminescent agent is 1.4 mM), and it is dissolved in chloroform.

[0069] The absorption and emission spectra of photosensitizer PtOEP (50 mM) and luminescent agent DPA (1.4 mM) are as follows: Figure 1 As shown. By Figure 1 (Left) As can be seen, the Soret band of PtOEP is at 381 nm, and the Q-band absorption peaks are at 501 nm and 536 nm, respectively. When the PtOEP solution (chloroform, not degassed) is excited with a 536 nm xenon lamp, a very weak fluorescence peak is observed at 587 nm, while strong phosphorescence is produced at 648 nm (with a shoulder peak at 718 nm). Figure 1 (Right) As can be seen, the luminescent agent DPA exhibits characteristic vibrational peaks of anthracene in the range of 350–400 nm, with peak positions located between 356 nm and 395 nm. When excited by a 395 nm xenon lamp, DPA produces blue fluorescence peaks at 411 nm and 430 nm, while the fluorescence peak of the solid luminescent agent DPA is located at 443 nm.

[0070] A multi-wavelength tropical-excited upconversion solution was added to a quartz cuvette, and nitrogen gas was purged for 15 minutes to remove oxygen. The cuvette cap was then tightened, and the cuvette was placed on an optical platform. The cuvette was then irradiated with semiconductor lasers at 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm, respectively, and the results were recorded. Figures 2-9 .by Figure 2 For example, under 532 nm excitation, the PtOEP / DPA solution (50 µM / 1.4 mM, degassed, chloroform) emits a green upconversion (peak at 430 nm). The left figure shows the relationship between the upconversion spectral intensity and the excitation power density, while the right figure shows the corresponding logarithm of the upconversion integral versus the logarithm of the power density (excitation intensity). It can be seen that as the excitation intensity increases, the blue upconversion intensity also increases (left figure). Plotting the logarithm of the upconversion intensity against the logarithm of the excitation power density (right figure), two straight lines with slopes of ~2 and ~1 are obtained through fitting. The intersection of these two lines is the excitation threshold. The smaller this value, the more effective the triplet annihilation process between the luminescent molecules. Since the excitation source used is a 532 nm green light source, this upconversion results in green-to-blue emission, and the anti-Stokes shift of the green-to-blue upconversion is 0.55 eV.

[0071] The upconversion spectra obtained by tropical excitation (i.e., using 589 nm, 635 nm, 655 nm, and 671 nm as excitation sources, respectively) were also tested using a similar method. These experimental data confirm that the PtOEP / DPA solution disclosed in this invention achieves multi-wavelength tropical-excited TTA upconversion emission and obtains the largest anti-Stokes shift (1.04 eV) in this binary system.

[0072] Example 1

[0073] The preparation method of multi-wavelength tropical-excited upconversion doped microcrystalline solid (PtOEP / DPA) is as follows: A tetrahydrofuran solution is prepared with a photosensitizer / luminescent agent molar ratio of 1:1000–100000 (with a fixed luminescent agent concentration of 10 mM); this solution is then injected into 20 mL of stirred deionized water and stirred for 10 minutes; the solution is filtered; the filter cake is dried in a vacuum drying oven, and the resulting doped microcrystalline solid is placed in air for testing. The advantage of this upconversion solid system is that it does not require encapsulation (no oxygen removal is needed), and the upconversion luminescence of the solid can be stably maintained for at least 20 days. Figures 10-17 Particle distribution diagrams and XRD patterns of PtOEP / DPA microcrystals with different molar ratios are shown. Figures 18-21 The images show the upconversion spectra of PtOEP / DPA microcrystalline solids with different doping ratios under different wavelength excitation.

[0074] Microcrystalline powder is sandwiched between two carrier wafers (no encapsulation required), and then the wafer is placed upright on an optical platform. The carrier wafers containing the microcrystalline powder are then irradiated with semiconductor lasers of different wavelengths (at 45° angles). 0 (Angle), record as follows Figures 22-26 The upconversion spectrum. For example... Figure 22 (Left) shows the relationship between upconversion intensity and excitation power density under 532 nm excitation; Figure 22 (Right) A plot of the corresponding logarithm of the upconversion integral versus the logarithm of the power density yields slopes of 2.0 and 1.0. Since the excitation source used is a 532nm green light source, this upconversion results in green-to-blue emission with an anti-Stokes shift of 0.47 eV.

[0075] Tropical excitation upconversion spectra obtained under laser excitation at wavelengths of 589 nm, 635 nm, 655 nm, and 671 nm are shown in [reference needed]. Figures 23-26 This invention confirms that multi-wavelength tropical excitation TTA upconversion can be achieved in the PtOEP / DPA microcrystalline split disclosed for the first time, with a maximum anti-Stokes shift of 0.95 eV.

[0076] Example 3: Upconversion Oxygen Resistance Spectroscopic Test of Doped Microcrystals

[0077] Solid microcrystals (PtOEP / DPA molar ratio of 1 / 1000–12000) were fully exposed to air. Upconversion spectra were measured daily at the same time (for twenty consecutive days), and the upconversion spectra were recorded as follows: Figures 27-38 As shown on the left; Figures 27-38 (Right) shows the upconversion intensity versus time curve. The fitted curve (right figure) shows that the solid microcrystals, when exposed to air, still exhibit good upconversion luminescence stability even after 20 days.

[0078] Example 4: Encryption and Anti-counterfeiting Application of Doped Microcrystals

[0079] like Figure 39 As shown, the gaps between the numbers "1" to "9" are filled with doped microcrystalline powder (PtOEP / DPA, 1 / 100000, mol / mol), while other areas are filled with a single-component luminescent agent (DPA). Under visible light, the "88" pattern appears white, but under ultraviolet light, it appears blue. When irradiated with semiconductor lasers at 532 nm (green), 589 nm (yellow), and 635 nm (red), only the areas filled with the two-component solid microcrystalline powder emit upconversion blue light; the areas filled with the single-component DPA powder do not emit upconversion blue light, thus realizing the "UC" encryption pattern.

[0080] This invention challenges the absorption limitation of the photosensitizer PtOEP, which can only be excited at the ground state zero vibrational level. It demonstrates for the first time the feasibility of multi-wavelength tropical excitation (TTA-UC) and shows promising application prospects. Selective excitation of the PtOEP photosensitizer at 532 nm, 589 nm, 635 nm, 655 nm, and 671 nm induces a blue upconversion in the luminescent agent DPA, achieving the largest anti-Stokes shift value (0.95–1.04 eV) for this binary system to date. Furthermore, it provides an anti-counterfeiting and encryption application using PtOEP / DPA solid microcrystals.

[0081] Comparison Example

[0082] The chemical structural formulas of platinum(II) octaethylporphyrin (PtOEP), 9,10-bis(p-methoxyphenyl)anthracene (DMOPA), and 9,10-bis(butoxy)anthracene (DBOPA) are as follows:

[0083]

[0084] Figure 40 shows the absorption and emission spectra of PtOEP (10 mM) and DMOPA (10 mM) (solvent: DMF). Figure 41Figure 41 shows the upconversion spectrum of PtOEP / DMOPA solution (degassed DMF) under 532 nm excitation (PtOEP / DMOPA concentration of 50 µM / 1.4 mM); Figure 42 shows the upconversion spectrum of PtOEP / DMOPA solution (degassed DMF) under 589 nm excitation (PtOEP / DMOPA concentration of 50 µM / 1.4 mM). It is evident that the control sample can only obtain a blue upconversion spectrum at the ground state zero vibrational level (532 nm) (see Figure 42). Figure 41 However, no blue upconversion spectrum was measured under tropical wavelength excitation (589 nm) (see...). Figure 42 ).

[0085] Figure 43 shows the absorption and emission spectra of PtOEP (10 mM) and DBOPA (10 mM) (solvent: DMF); Figure 44 shows the upconversion spectrum of PtOEP / DBOPA solution (degassed DMF) under 532 nm excitation (PtOEP / DBOPA concentration: 50 µM / 1.4 mM); Figure 45 shows the upconversion spectrum of PtOEP / DBOPA solution (degassed DMF) under 589 nm excitation (PtOEP / DBOPA concentration: 50 µM / 1.4 mM). It can be seen that the control sample can only obtain a blue upconversion spectrum at the ground state zero vibrational level (532 nm) (see Figure 43). Figure 44 However, no blue upconversion spectrum was measured under tropical wavelength excitation (589 nm) (see...). Figure 45 ).

[0086] This invention obtains a binary system with a large anti-Stokes upconversion shift (e.g., 0.95 eV in solid microcrystalline powder and 1.04 eV in solution), solving the problem of small anti-Stokes upconversion shifts (e.g., 0.59 eV in solid and 0.87 eV in solution) in the applicant's online application. The upconversion microcrystals obtained by this invention exhibit "red-to-blue," "yellow-to-blue," and "green-to-blue" upconversion (see...). Figure 39 This invention provides a multi-channel (three-channel) visual anti-counterfeiting identification mark, while existing microcrystals can only achieve "red-to-yellow" and "near-infrared-to-yellow" upconversion, with fewer anti-counterfeiting channels (two) and weaker visual appeal. The upconversion microcrystals obtained in this invention can achieve strong upconversion without encapsulation (tested directly in air), solving the problem that in online applications, upconversion microcrystals need to be encapsulated (isolated from air), resulting in weaker upconversion intensity.

Claims

1. A multi-wavelength tropical-excited TTA upconversion-doped microcrystal, characterized in that, It consists of a platinum photosensitizer and a 9,10-diphenylanthracene luminescent agent; the platinum photosensitizer is platinum(II) octaethylporphyrin; a tetrahydrofuran solution is prepared according to a photosensitizer / luminescent agent molar ratio of 1:1000-100000; then it is injected into 20 mL of deionized water under stirring, stirred for 10 minutes; filtered; the filter cake is dried in a vacuum drying oven to obtain multi-wavelength tropical excited TTA upconversion solid microcrystalline powder; the luminescent agent concentration is 10 mM.

2. The method for preparing multi-wavelength tropical excited TTA upconversion doped microcrystals according to claim 1, characterized in that, A tetrahydrofuran solution was prepared with a photosensitizer / luminescent agent molar ratio of 1:1000 to 100000; then it was injected into 20 mL of deionized water under stirring for 10 minutes; the solution was filtered; the filter cake was dried in a vacuum drying oven to obtain multi-wavelength tropical excited TTA upconversion solid microcrystalline powder; the luminescent agent concentration was 10 mM.

3. The application of the multi-wavelength tropical-excited TTA upconversion doped microcrystals as described in claim 1 in the preparation of multi-wavelength tropical-excited triplet-triplet annihilation upconversion materials.

4. The application according to claim 3, characterized in that, The multi-wavelength tropical-excited TTA upconversion material is a blue light conversion material.

5. The application according to claim 4, characterized in that, The multi-wavelength tropical excited TTA upconversion material is a red-to-blue, yellow-to-blue, or green-to-blue upconversion material.

6. The application of the multi-wavelength tropical-excited TTA upconversion doped microcrystals described in claim 1 in anti-counterfeiting multi-information encryption.

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