Inp / zns quantum dot-based tta-uc luminescent material, preparation method and application thereof

Abstract

The application discloses an InP / ZnS quantum dot-based TTA-UC luminescent material and a preparation method and application thereof. The InP / ZnS core-shell quantum dot is used as a triplet state sensitizing agent, and 1-pyrene carboxylic acid is used as a bridging molecule to form a quantum dot-PCA / / DPA ternary composite interface with an organic annihilator 9,10-diphenyl anthracene. Under the premise that the size of the quantum dot is not obviously changed, by adjusting the Br / Cl halogen ratio in the indium source and the zinc source, the quantum dot lattice defect passivation and the triplet state energy transfer level matching are simultaneously realized, so that the triplet state energy transfer efficiency of the system is significantly improved, and the highest (19.75%) up-conversion fluorescence quantum yield in the quantum dot composite system with DPA as the annihilator is obtained. The preparation scheme can be expanded to other TTA-UC systems with InP quantum dots as the sensitizing agent, and can be widely applied to the fields of photocatalysis, solar cells and biological imaging.

Description

Technical Field

[0001] This invention belongs to the field of photon upconversion luminescent materials technology, specifically relating to a TTA-UC luminescent material based on InP / ZnS quantum dots, its preparation method, and its application. Background Technology

[0002] Photon upconversion technology can convert low-energy photons into high-energy photons, which is of great value in expanding the photoresponse range and improving photon utilization efficiency. Among them, triplet-triplet annihilation photon upconversion (TTA-UC) has become a research hotspot in recent years due to its advantages such as low excitation power requirement, spectral tunability, and high efficiency in response to incoherent light (such as sunlight), showing broad application prospects in photocatalysis, solar cells, biosensing and other fields.

[0003] Quantum dots, as a novel type of nanomaterial for photosensitizing light, possess characteristics such as broad and tunable absorption spectra, high molar extinction coefficients, and easily tunable triplet lifetimes, making them widely used as photosensitizers in the construction of TTA-UC systems. However, existing quantum dot-based TTA-UC composite systems still face several key challenges: First, the low triplet energy transfer efficiency between quantum dots and TTA annihilators limits the upconversion quantum yield, with the upconversion efficiency for visible light generally below 15%. Second, existing preparation methods often rely on complex in-situ polymerization or layer-by-layer deposition processes, which are cumbersome, costly, and difficult to scale up. Third, existing quantum dot-based TTA-UC systems often use Pb- or Cd-containing quantum dots, which contradicts sustainable development principles. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a TTA-UC luminescent material based on InP / ZnS quantum dots, its preparation method, and its applications. This invention precisely controls the microstructure of the quantum dots and the energy level matching of the system by changing the ratio of Br and Cl in the indium and zinc sources, achieving efficient interfacial energy transfer and TTA-UC between the quantum dots and intermediate ligand molecules and the organic annihilation agent DPA molecules. This quantum dot preparation method is simple and scalable, and can promote the practical application of this type of material system in fields such as green photocatalysis, solar energy conversion, and deep tissue imaging.

[0005] The objective of this invention is achieved through the following technical solution: A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots includes the following steps: S1. Under a nitrogen atmosphere, indium source, zinc source and oleylamine are mixed, vacuumed and degassed, then heated to 100~140℃ and held for 40~120min. After switching to nitrogen atmosphere, the mixture is heated to 140~165℃, hexaethylphosphoric triamine is added and the reaction is held for 18~30min. The indium source is selected from at least one of indium chloride and indium bromide; the zinc source is selected from at least one of zinc chloride and zinc bromide. S2. Cool the sample from step S1 to 70~130℃, vacuum for 3~10 min, add S-TOP solution and zinc precursor solution, and after the addition is complete, heat the system to 230~280℃ and keep it at that temperature for 30~80 min. After cooling, the crude product is obtained. S3. Centrifuge the crude product and collect the supernatant. Mix the supernatant with anhydrous ethanol and centrifuge again. Discard the supernatant and disperse the resulting precipitate with n-hexane to obtain an InP / ZnS quantum dot dispersion. S4. Mix the InP / ZnS quantum dot dispersion, 9,10-diphenylanthracene, 1-pyrene carboxylic acid, and nonpolar organic solvent evenly to obtain the luminescent material.

[0006] Preferably, the ratio of indium source, zinc source and oleylamine used in step S1 is 0.1~0.16g:0.3~0.496g:9mL.

[0007] Preferably, the volume ratio of hexaethylphosphoric triamine to oleylamine in step S1 is 0.5:9.

[0008] Preferably, the volume ratio of the S-TOP solution, zinc precursor solution and oleylamine in step S2 to that in step S1 is 0.35:3.5:9.

[0009] Preferably, the S-TOP solution in step S2 is prepared by dissolving sulfur powder in trioctylphosphine, wherein the concentration of sulfur powder in trioctylphosphine is 0.0704 g / mL.

[0010] Preferably, the zinc precursor solution in step S2 is prepared by dissolving zinc stearate in 1-octadecene, wherein the concentration of zinc stearate in 1-octadecene is 0.25 g / mL.

[0011] Preferably, the specific steps for centrifuging the crude product and collecting the supernatant in step S3 are as follows: transfer the crude product to a centrifuge tube, centrifuge at 8000 rpm for 7 min, and collect the supernatant.

[0012] Preferably, the specific steps for mixing the supernatant with anhydrous ethanol and centrifuging again in step S3 are as follows: mix the supernatant with anhydrous ethanol in a volume ratio of 1:3, and centrifuge again at 8000 rpm for 7 min.

[0013] Preferably, the concentration of the InP / ZnS quantum dot dispersion in step S3 is 0.5~5 μmol / L.

[0014] Preferably, the specific operation of uniformly mixing the InP / ZnS quantum dot dispersion, 9,10-diphenylanthracene, 1-pyrene carboxylic acid, and nonpolar organic solvent in step S4 is as follows: The nonpolar organic solvent is divided into a first solvent and a second solvent; The 9,10-diphenylanthracene was dissolved in the first solvent to obtain a stock solution with a concentration of 10-60 mmol / L; The 1-pyrenic acid was added to the InP / ZnS quantum dot dispersion, and after ultrasonic treatment, it was filtered to obtain a complex solution. Simply mix the complex solution, the stock solution, and the second solvent until homogeneous.

[0015] Preferably, the first solvent is n-hexane or toluene; the second solvent is n-hexane or toluene.

[0016] Preferably, the amount of 1-pyrene carboxylic acid added to the InP / ZnS quantum dot dispersion is 0.1~3 mg / mL.

[0017] Preferably, the volume ratio of the complex solution, the stock solution, and the second solvent is 1~6:3~30:6~50.

[0018] The TTA-UC luminescent material prepared by the above method based on InP / ZnS quantum dots is a TTA-UC luminescent material.

[0019] The above-mentioned TTA-UC luminescent materials have applications in photocatalysis, solar energy utilization, and bioimaging.

[0020] Compared with the prior art, the beneficial effects of the present invention include: This invention is based on precise control of synthesis reaction parameters. Without changing the quantum dot size, it optimizes the microscopic chemical state and energy level structure of InP / ZnS quantum dots by adjusting the Br / Cl ratio in the indium and zinc sources. This simultaneously achieves effective passivation of quantum dot lattice defects and matching of triplet energy transfer energy levels between the quantum dots and ligand molecules. This maximizes the optimization of the driving force loss in the triplet energy transfer (TTET) process, significantly improves TTET efficiency, and ultimately achieves high quantum yield photon upconversion. Attached Figure Description

[0021] Figure 1 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 1.

[0022] Figure 2 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 2.

[0023] Figure 3Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 3.

[0024] Figure 4 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 4.

[0025] Figure 5 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 5.

[0026] Figure 6 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 6.

[0027] Figure 7 X-ray diffraction patterns of InP / ZnS quantum dots prepared in Examples 1 and 6.

[0028] Figure 8 Steady-state photoluminescence (PL) spectra of the InP / ZnS-PCA systems prepared in Examples 1 and 6 under 516 nm excitation.

[0029] Figure 9 The transient absorption kinetics curves of the InP / ZnS quantum dots prepared in Examples 1 and 6 and the corresponding InP / ZnS-PCA systems at specific probe wavelengths.

[0030] Figure 10 The graph shows the changes in upconversion luminescence intensity and excitation power of the InP / ZnS-PCA / / DPA systems prepared in Examples 1 and 6. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] Example 1 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.1 g InCl3, 0.3 g ZnCl2 and 9 mL oleylamine (OAM) sequentially to a three-necked flask. Evacuate and degas the system, then heat to 120°C and maintain for 60 min. After that, switch to a nitrogen atmosphere and continue heating to 150°C. Quickly inject 0.5 mL hexaethylphosphoric triamine and react at 150°C for 22 min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS1 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS1 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution (denoted as InP / ZnS-PCA). Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material (denoted as InP / ZnS-PCA / / DPA).

[0033] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0034] Figure 1 Transmission electron microscopy (TEM) images and particle size distribution diagrams of InP / ZnS quantum dots prepared in Example 1 are shown below. Figure 1 We can see that the average particle size of the quantum dots prepared in Example 1 is 2.9 ± 0.2 nm.

[0035] Example 2 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.1g InCl3, 0.099g ZnBr2, 0.24g ZnCl2 and 9mL oleylamine (OAM) sequentially to a three-necked flask (the Br:Cl molar ratio is 0.19 at this time). Evacuate and degas the system, then heat to 120℃ and maintain for 60min. After that, switch to a nitrogen atmosphere and continue heating to 150℃. Quickly inject 0.5 mL of hexaethylphosphoric triamine and react at 150℃ for 22min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS2 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS2 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution. Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material.

[0036] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0037] Figure 2 Transmission electron microscopy (TEM) images and particle size distribution diagrams of InP / ZnS quantum dots prepared in Example 2 are shown below. Figure 2 We can see that the average particle size of the quantum dots prepared in Example 2 is 2.9 ± 0.2 nm.

[0038] Example 3 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.1g InCl3, 0.248g ZnBr2, 0.15g ZnCl2 and 9mL oleylamine (Br:Cl molar ratio is 0.67) sequentially to a three-necked flask. Evacuate and degas the system, then heat to 120℃ and maintain for 60min. After that, switch to a nitrogen atmosphere and continue heating to 150℃. Quickly inject 0.5mL hexaethylphosphoric triamine and react at 150℃ for 22min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS3 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS3 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution. Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material.

[0039] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0040] Figure 3Transmission electron microscopy (TEM) images and particle size distribution diagrams of InP / ZnS quantum dots prepared in Example 3 are shown below. Figure 3 We can see that the average particle size of the quantum dots prepared in Example 3 is 3.1 ± 0.2 nm.

[0041] Example 4 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.1g InCl3, 0.396g ZnBr2, 0.06g ZnCl2 and 9mL oleylamine (Br:Cl molar ratio is 1.8) sequentially to a three-necked flask. Evacuate and degas the system, then heat to 120℃ and maintain for 60min. After that, switch to a nitrogen atmosphere and continue heating to 150℃. Quickly inject 0.5mL hexaethylphosphoric triamine and react at 150℃ for 22min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS4 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS4 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution. Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material.

[0042] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0043] Figure 4 Transmission electron microscopy (TEM) images and particle size distribution diagrams of InP / ZnS quantum dots prepared in Example 4 are shown below. Figure 4 We can see that the average particle size of the quantum dots prepared in Example 4 is 3.1 ± 0.2 nm.

[0044] Example 5 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.1g InCl3, 0.496g ZnBr2 and 9mL oleylamine (OAM) sequentially to a three-necked flask (the Br:Cl molar ratio is 4.09 at this time). Evacuate and degas the system, then heat to 120℃ and maintain for 60min. After that, switch to a nitrogen atmosphere and continue heating to 150℃. Quickly inject 0.5mL hexaethylphosphoric triamine and react at 150℃ for 22min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS5 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS5 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution. Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material.

[0045] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0046] Figure 5Transmission electron microscopy (TEM) images and particle size distribution diagrams of InP / ZnS quantum dots prepared in Example 5 are shown below. Figure 5 We can see that the average particle size of the quantum dots prepared in Example 5 is 3.0 ± 0.2 nm.

[0047] Example 6 A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, the specific steps of which are as follows: S1. In a glove box under a nitrogen atmosphere, add 0.16 g InBr3, 0.495 g ZnBr2 and 9 mL oleylamine (OAM) sequentially to a three-necked flask. Evacuate and degas the system, then heat to 120 °C and maintain for 60 min. After that, switch to a nitrogen atmosphere and continue heating to 150 °C. Quickly inject 0.5 mL hexaethylphosphoric triamine and react at 150 °C for 22 min. S2. After the reaction is complete, the heater temperature is set to 120℃. The reaction solution is rapidly cooled to this temperature by air cooling and then evacuated for 5 minutes. Subsequently, 0.35 mL of S-TOP solution (prepared by dissolving 0.2112 g of sulfur powder in 3 mL of trioctylphosphine (TOP)) and 3.5 mL of zinc precursor solution (prepared by dissolving 3 g of zinc stearate in 12 mL of 1-octadecene (ODE)) are added sequentially. After the addition is complete, the reaction system is gradually heated to 250℃ and the reaction is continued at this temperature for 40 minutes. After the shell growth is complete, the heater is turned off and the heating jacket is removed. The temperature of the reaction solution is first cooled to below 200℃ by air cooling and then placed in a cold water bath to cool to room temperature to obtain the crude product. S3. Transfer the obtained crude product to a centrifuge tube and centrifuge at 8000 rpm for 7 min. Collect the supernatant and add ethanol at a volume ratio of 1:3 (supernatant to anhydrous ethanol). Mix well and centrifuge again at 8000 rpm for 7 min. Discard the supernatant and dissolve the precipitate in 5 mL of n-hexane to obtain a 1 μmol / L InP / ZnS6 core-shell quantum dot n-hexane dispersion. All purification operations were completed in a nitrogen glove box, and the final product was stored in the glove box for later use. S4. Dissolve 100 mg of 9,10-diphenylanthracene (DPA) powder in 10 mL of toluene and stir for 30 min until completely dissolved to prepare a DPA stock solution with a concentration of 30.3 mmol / L. Take a 5 mL glass bottle and add 0.5 mg of 1-pyrene carboxylic acid (PCA) powder directly to 1 mL of the prepared InP / ZnS6 quantum dot n-hexane dispersion (the absorbance of this quantum dot solution at 500 nm in a 1 mm optical path cuvette is 0.2). After sonicating for 3 min, filter the mixture using a nylon membrane to obtain a clear composite solution. Take a 5 mL glass bottle, add 300 µL of the composite solution (concentration of 1 µmol / L), then add 1000 µL of DPA stock solution and 1700 µL of n-hexane to make the total volume 3 mL, thus obtaining the TTA-UC luminescent material.

[0048] The prepared TTA-UC luminescent material and the reference sample were transferred to quartz cuvettes with a 1 cm optical path for photon upconversion performance testing. The reference sample was prepared as follows: 3000 µL of an ethanol solution of Rhodamine B (RhB) was added to another 5 mL glass bottle, and its concentration was adjusted so that its absorbance at 500 nm in a 1 mm cuvette was 0.2, which was used for subsequent upconversion quantum yield calculation.

[0049] Figure 6 Transmission electron microscopy (TEM) image and particle size distribution of InP / ZnS quantum dots prepared in Example 6. Figure 6 We can see that the average particle size of the quantum dots prepared in Example 6 is 3.0 ± 0.2 nm.

[0050] Figure 7 The X-ray diffraction patterns of InP / ZnS quantum dots prepared in Examples 1 and 6 are shown below. Figure 7 We can see that the InP / ZnS quantum dots in Examples 1 and 6 show diffraction peaks at approximately 27°, 45°, and 55° corresponding to the InP standard card, confirming the presence of InP. Moreover, the peak position in Example 6 corresponds more accurately to the standard diffraction peak than that in Example 1, indicating that a higher Br / Cl ratio can optimize the crystal structure and reduce lattice defects.

[0051] Figure 8 The steady-state photoluminescence (PL) spectra of the InP / ZnS-PCA systems prepared in Examples 1 and 6 under 516 nm excitation are shown below. Figure 8 We can see that the fluorescence quenching efficiency of the InP / ZnS-PCA system in Example 1 is low, while the fluorescence quenching efficiency of the core-shell quantum dot in Example 6 is high.

[0052] Using femtosecond transient absorption spectroscopy, under 516 nm light excitation and with white light detection in the 340–800 nm range, the InP / ZnS quantum dots prepared in Examples 1 and 6 and their corresponding InP / ZnS-PCA systems were subjected to TA tests. The test results are as follows: Figure 9 As shown.

[0053] Figure 9 Transient absorption kinetics curves of the InP / ZnS quantum dots prepared in Examples 1 and 6 and the corresponding InP / ZnS-PCA systems at specific probe wavelengths. Figure 9We can see that, compared to Example 1, the exciton bleaching signal decay of InP / ZnS quantum dots after bonding with PCA molecules in Example 6 is significantly accelerated, indicating efficient triplet energy transfer between InP / ZnS quantum dots and PCA.

[0054] The prepared solution was excited using a 516 nm continuous-wave laser. The excitation power was adjusted using a pre-attenuator. A lens group was used to focus the photon upconversion fluorescence into the optical fiber at a position perpendicular to the optical path. The other end of the fiber was connected to a fiber optic spectrometer for detection. The detection results are as follows: Figure 10 As shown.

[0055] Figure 10 The graph shows the changes in upconversion luminescence intensity and excitation power of the InP / ZnS-PCA / / DPA systems prepared in Examples 1 and 6. Figure 10 We can see that under optimized conditions, the energy transfer efficiency of the quantum dot excited state to the annihilator DPA through PCA is significantly improved, thereby enhancing the upconversion luminescence. Spectally, this is manifested as fluorescence quenching of the quantum dots near 550 nm, while the upconversion luminescence intensity of DPA increases.

[0056] In the InP / ZnS-PCA / / DPA system described in this invention, electron microscopy results show that the quantum dot sizes in each embodiment are essentially consistent. X-ray diffraction results indicate that adjusting the Br / Cl ratio can optimize the crystal structure and reduce lattice defects. Steady-state fluorescence emission and transient absorption spectra reveal the variation of the triplet energy transfer process with the Br / Cl ratio, indicating that the crystal structure can be optimized and lattice defects reduced by adjusting the Br / Cl ratio in the precursor solution without changing the quantum dot size. Simultaneously, it achieves good triplet energy transfer level matching with the intermediate ligand molecules, thereby realizing high-efficiency photon upconversion luminescence.

[0057] The physicochemical properties and luminescence performance parameters of the different quantum dots and upconversion systems prepared in Examples 1-6 are summarized, and the results are shown in Table 1. Rhodamine with a fluorescence quantum yield of 65% was used as a standard reference in each example to determine and calibrate the photon upconversion efficiency of the system.

[0058] Table 1 Summary of performance parameters for Examples 1-6

[0059] In summary, this invention provides a complete fabrication scheme for a high-performance, heavy metal-free TTA-UC system. This system achieves a synergistic improvement in photon upconversion efficiency and environmental compatibility, and its fabrication process is simple. The strategy of passivating quantum dot lattice defects and optimizing energy conversion efficiency based on the halogen ratio (Br / Cl) of indium and zinc sources can be extended to similar systems. This invention can promote the practical application of photon upconversion technology, particularly in the biomedical and green energy fields where both material safety and system upconversion efficiency are critical, and has significant scientific and practical value.

[0060] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing TTA-UC luminescent materials based on InP / ZnS quantum dots, characterized in that, The steps include the following: S1. Under a nitrogen atmosphere, indium source, zinc source and oleylamine are mixed, vacuumed and degassed, then heated to 100~140℃ and held for 40~120min. After switching to nitrogen atmosphere, the mixture is heated to 140~165℃, hexaethylphosphoric triamine is added and the reaction is held for 18~30min. The indium source is selected from at least one of indium chloride and indium bromide; the zinc source is selected from at least one of zinc chloride and zinc bromide. S2. Cool the sample from step S1 to 70~130℃, vacuum for 3~10 min, add S-TOP solution and zinc precursor solution, and after the addition is complete, heat the system to 230~280℃ and keep it at that temperature for 30~80 min. After cooling, the crude product is obtained. S3. Centrifuge the crude product and collect the supernatant. Mix the supernatant with anhydrous ethanol and centrifuge again. Discard the supernatant and disperse the resulting precipitate with n-hexane to obtain an InP / ZnS quantum dot dispersion. S4. Mix the InP / ZnS quantum dot dispersion, 9,10-diphenylanthracene, 1-pyrene carboxylic acid, and nonpolar organic solvent evenly to obtain the luminescent material.

2. The preparation method of the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 1, characterized in that, The ratio of indium source, zinc source, and oleylamine used in step S1 is 0.1~0.16g : 0.3~0.496g : 9mL; and / or The volume ratio of hexaethylphosphoric triamine to oleylamine in step S1 is 0.5:

9.

3. The preparation method of the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 1, characterized in that, The volume ratio of the S-TOP solution, zinc precursor solution, and oleylamine described in step S2 to that described in step S1 is 0.35:3.5:9; and / or The S-TOP solution mentioned in step S2 is prepared by dissolving sulfur powder in trioctylphosphine, wherein the concentration of sulfur powder in trioctylphosphine is 0.0704 g / mL.

4. The preparation method of the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 1, characterized in that, The zinc precursor solution in step S2 is prepared by dissolving zinc stearate in 1-octadecene, wherein the concentration of zinc stearate in 1-octadecene is 0.25 g / mL; and / or The specific steps for centrifuging the crude product and collecting the supernatant in step S3 are as follows: transfer the crude product to a centrifuge tube, centrifuge at 8000 rpm for 7 min, and collect the supernatant.

5. The method for preparing the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 1, characterized in that, The specific steps for mixing the supernatant with anhydrous ethanol and centrifuging again in step S3 are as follows: mix the supernatant with anhydrous ethanol at a volume ratio of 1:3, and centrifuge again at 8000 rpm for 7 min; and / or The concentration of the InP / ZnS quantum dot dispersion in step S3 is 0.5~5 μmol / L.

6. The method for preparing the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 1, characterized in that, The specific operation of mixing the InP / ZnS quantum dot dispersion, 9,10-diphenylanthracene, 1-pyrene carboxylic acid, and nonpolar organic solvent uniformly in step S4 is as follows: The nonpolar organic solvent is divided into a first solvent and a second solvent; The 9,10-diphenylanthracene was dissolved in the first solvent to obtain a stock solution with a concentration of 10-60 mmol / L; The 1-pyrene carboxylic acid was added to the InP / ZnS quantum dot dispersion, and after ultrasonic treatment, it was filtered to obtain a complex solution. Simply mix the complex solution, the stock solution, and the second solvent until homogeneous.

7. The method for preparing the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 6, characterized in that, The first solvent is n-hexane or toluene; the second solvent is n-hexane or toluene.

8. The method for preparing the TTA-UC luminescent material based on InP / ZnS quantum dots according to claim 6, characterized in that, The amount of 1-pyrene carboxylic acid added to the InP / ZnS quantum dot dispersion is 0.1~3 mg / mL; and / or The volume ratio of the complex solution, the stock solution, and the second solvent is 1~6:3~30:6~50.

9. A TTA-UC luminescent material, characterized in that, It is prepared by the preparation method of TTA-UC luminescent material based on InP / ZnS quantum dots as described in any one of claims 1 to 8.

10. The application of the TTA-UC luminescent material according to claim 9 in the fields of photocatalysis, solar energy utilization and bioimaging.

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