WO2022143343A1

WO2022143343A1 - Quantum dot dispersion solution and quantum dot storage method

Info

Publication number: WO2022143343A1
Application number: PCT/CN2021/140506
Authority: WO
Inventors: 周礼宽; 杨一行
Original assignee: Tcl科技集团股份有限公司
Priority date: 2020-12-28
Filing date: 2021-12-22
Publication date: 2022-07-07
Also published as: CN114686203B; CN114686203A

Abstract

The present disclosure relates to a quantum dot dispersion solution and a quantum dot storage method. The quantum dot dispersion solution comprises a dispersant, a quantum dot, and a reducing organic matter. The quantum dot dispersion solution of the present disclosure comprises the reducing organic matter, and the reducing organic matter can eliminate and resist oxidation reaction factors generated by factors, such as water, oxygen, and lighting, from the dispersant and air, thereby effectively ensuring the fluorescence stability of the quantum dot in a storage process, and solving the problem of the reduction of the fluorescence quantum yield caused due to the fact that a purified quantum dot is affected by the factors, such as water, oxygen, and light, in the storage process.

Description

A kind of quantum dot dispersion liquid and quantum dot preservation method

priority

This disclosure claims the priority of a Chinese patent application with an application date of December 28, 2020, an application number of "202011583569.7" and an application title of "A quantum dot dispersion liquid and a method for storing quantum dots", the entire contents of which are incorporated by reference in this disclosure.

technical field

The present disclosure relates to the technical field of quantum dots, and in particular, to a quantum dot dispersion liquid and a quantum dot storage method.

Background technique

Quantum dots (quantum dot light-emitting materials) generally consist of inorganic nanocrystals and surface ligands formed on the surfaces of the inorganic nanocrystals, wherein the inorganic nanocrystals may be core-shell structured inorganic nanocrystals. The core-shell structure inorganic nanocrystal specifically includes a quantum dot crystal core and a multi-shell layer structure covering the quantum dot crystal core. In the quantum dots, the crystal cores of the quantum dots are connected with the surface ligands through the multi-shell layer, so that a quantum dot light-emitting material with high fluorescence quantum efficiency and good stability can be obtained.

In the production and preparation process, the synthesized quantum dots need to be preserved. Specifically, after the synthesized quantum dots are purified, they are dispersed into an organic phase, an alcohol phase or an aqueous phase solvent for low temperature preservation. However, the problem of fast or slow fluorescence quantum yield decay occurs during the storage process of quantum dot luminescent materials.

Therefore, the existing technology still needs to be improved and developed.

public content

In view of the above-mentioned deficiencies of the prior art, the purpose of the present disclosure is to provide a quantum dot dispersion liquid and a quantum dot storage method, aiming at solving the problem that the quantum dot luminescent material will decay in fluorescence quantum yield during storage.

A quantum dot dispersion liquid, comprising: a dispersant, quantum dots and reducing organic matter.

The quantum dot dispersion, wherein the reducing organic matter is selected from one or more of alcohols, phenols, aldehydes, organic amines, organic phosphorus, and olefins;

The reducing organic matter is selected from one or more of ethanolamine, tributylphosphine, and polyethylene glycol amine.

In the quantum dot dispersion, the quantum dots are quantum dots containing surface ligands.

In the quantum dot dispersion liquid, the surface ligands include one or more of carboxyl surface ligands, amine-based surface ligands, thiol surface ligands and phosphine-based surface ligands.

In the quantum dot dispersion, the reducing organic matter is a reducing organic matter containing a coordinating group.

In the quantum dot dispersion, the coordinating group includes at least one of a carboxyl group, an amine group, a mercapto group, and a phosphine group.

In the quantum dot dispersion, the coordination activity of the coordinating group and the quantum dot is stronger than the coordination activity of the surface ligand and the quantum dot.

The quantum dot dispersion liquid, wherein, the dispersing agent comprises chloroform, toluene, n-hexane, cyclohexane, n-heptane, decane, n-octane, cycloheptane, dioxane, water, methanol, One or more of ethanol, isopropanol, n-butanol;

The molar ratio of the reducing organic matter to the quantum dots is 0.5:1 to 2:1;

In the quantum dot dispersion liquid, the concentration of the quantum dots is 1 mmol/mL～100 mmol/mL;

The quantum dots are selected from one or more of group II-VI compound quantum dots, group IV-VI compound quantum dots, group III-V compound quantum dots, and group I-VI compound quantum dots.

In the quantum dot dispersion, the quantum dots are core-shell quantum dots formed by coating the quantum dot crystal core with a single-layer or multi-layer semiconductor material shell layer.

The quantum dot dispersion liquid, wherein, the quantum dot crystal nucleus is selected from CdSe, CdS, CdTe, CdSeTe, CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, At least one of InP, InAs, InZnP, InGaP, InGaN, CdZnSe, and CdZnSe.

In the quantum dot dispersion, the shell layer of the semiconductor material is selected from at least one of ZnSe, ZnS and ZnSeS.

In the quantum dot dispersion, the quantum dots are red quantum dots CdZnSe/ZnSe/ZnS or green quantum dots CdZnSe/ZnS.

A quantum dot preservation method, comprising:

The quantum dots, the reducing organic substance, and the dispersing agent are prepared into the quantum dot dispersion liquid according to any one of claims 1 to 8, and the quantum dots are stored.

The storage method for quantum dots, wherein the storage temperature is 20-30°C.

Beneficial effects: The quantum dot dispersion described in the present disclosure contains reducing organic matter, which can eliminate and resist oxidation reaction factors generated by factors such as dispersing agent and water, oxygen, and light in the air, thereby effectively ensuring that quantum dots are in The fluorescence stability during the storage process solves the problem of the reduction of the fluorescence quantum yield caused by the influence of water, oxygen, light and other factors during the storage process of the quantum dots.

Detailed ways

The present disclosure provides a quantum dot dispersion liquid and a quantum dot storage method. In order to make the purpose, technical solution and effect of the present disclosure clearer and clearer, the present disclosure will be further described below in detail. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, but not to limit the present disclosure.

When the quantum dots are stored, the synthesized quantum dots are separated from the reaction system containing the reaction solvent, unconverted precursors and excess organic ligands to obtain quantum dots composed of inorganic nanocrystals and organic surface ligands, The obtained quantum dots are dispersed in a solvent for preservation. The inventors found in their work on quantum dot luminescent materials that storage conditions such as temperature, illumination, and water-oxygen environment have important effects on the optical properties and stability of quantum dots.

Usually, according to the different properties of the surface ligands, the quantum dot inorganic nanocrystals are dispersed in different solvents, and the solvent can be an organic phase, an alcohol phase or an aqueous phase solvent. Since the surface ligands and the core-shell structure of the quantum dots are connected by coordination bonds, in the dispersant, the surface ligands are easily detached from the surface of the inorganic nanocrystals of the core-shell structure of the quantum dots, resulting in the formation of defects on the surface of the quantum dots. When an electron or hole is captured, it can act as an active center for a redox reaction that reacts with water and oxygen in the air, thereby destabilizing the quantum dot's fluorescence.

In addition, under short-wavelength ultraviolet light, the surface of the quantum dots adsorbs water molecules from the solvent or air environment, which oxidizes the metal atoms on the surface of the inorganic nanocrystals of the quantum dots, resulting in defects and a decrease in the fluorescence quantum efficiency.

At the same time, it was also found that the fluorescence intensity of purified quantum dots decreased linearly with the increase of storage temperature, mainly due to the decrease of quantum yield due to irreversible radiation or enhanced surface oxidation of inorganic nanocrystals of quantum dots.

Aiming at the problem of the decrease of the fluorescence quantum yield during the storage of quantum dot nanomaterials, the adverse effects of the erosion of the surface of quantum dots by water vapor, oxygen, light and other factors can be delayed to a certain extent by storing in an inert atmosphere away from light, but it cannot be improved. The problem of reduced fluorescence quantum yield due to surface ligand shedding. In addition, the harsh storage conditions of quantum dots add additional process costs. Therefore, there is an urgent need to find a solution that can effectively improve the reduction of fluorescence quantum yield during the storage process of quantum dots.

After research, quantum dots are purified and stored in organic phase, alcohol phase or aqueous phase solvent. Under the influence of environmental temperature, light, water and oxygen and other storage conditions, reactions such as oxidation will occur, interfering with mobile electrons and holes. , resulting in irreversible photoquenching. Among them, the water molecules adsorbed on the surface of the quantum dots will oxidize the surface of the quantum dots, resulting in a blue-shift of exciton emission, and finally introducing new surface defects, reducing the luminescence intensity of the quantum dots. The photo-oxidation of quantum dots will generate new defects to suppress the emission of excitons, resulting in lower luminescence quantum yields (luminescence QY). In addition to the surface ligands connected by coordination bonds in the outer layer of the quantum dot core, the wide bandgap shell also maintains the fluorescence quantum yield. However, in the wet oxygen environment, the surface of the quantum dot is freed by the oxygen formed on the surface of the wide bandgap shell. The effect of the radical anion adsorbate, resulting in a reduced degree of electron wavefunction confinement. In addition, oxygen has a certain permeability in the non-smooth energy level gradient between the core and shell of quantum dots. Even for quantum dots with thick shells, oxygen molecules can reach the core of quantum dots through the core-shell interface, resulting in defect vacancies and reduced fluorescence quantum yield. Rate.

The changes in photoluminescence properties caused by temperature are irreversible, which may be due to the increase of temperature, which leads to the enhancement of irreversible radiation and the occurrence of similar oxidation reactions, resulting in a decrease in fluorescence intensity or quantum yield and a change in the position of the emission peak. The state before the temperature rise cannot be restored.

The decay of the fluorescence quantum yield caused by the damage to the quantum dot structure caused by the factors of temperature, light, water and oxygen is directly related to the externally generated oxidation factor. The reducing organic matter method eliminates the oxidation factors generated by environmental factors such as temperature or light, water and oxygen, and avoids the irreversible damage to the surface or interior of the quantum dot caused by the negatively charged oxygen radicals caused by these oxidation factors, resulting in a decrease in the fluorescence quantum yield. , affecting the optoelectronic properties of quantum dots.

Embodiments of the present disclosure provide a quantum dot dispersion, which includes: a dispersant, quantum dots, and reducing organic matter.

In the embodiment of the present disclosure, by adding reducing organic matter to the dispersing agent, the reducing organic matter can eliminate and resist the oxidation reaction factors generated by the dispersing agent and factors such as water, oxygen, light in the air, etc., thereby effectively ensuring the long-term preservation of quantum dots It can effectively solve the problem of reducing the fluorescence quantum yield caused by the influence of water, oxygen, light and other factors during the storage process of quantum dots.

In one embodiment of the present disclosure, the reducing organic compound is an organic compound with weak reducibility, and the reducing organic compound is selected from one of alcohols, phenols, aldehydes, organic amines, organic phosphorus, and alkenes. one or more. The reducing organics in this embodiment are not limited to the above-mentioned types of reducing organics, for example, the reducing organics may also be other compounds containing double bonds. In the implementation process, the reducing organic matter that can be dispersed in the corresponding dispersing agent can be selected according to different dispersing agents.

In one embodiment of the present disclosure, in the quantum dot dispersion, the quantum dots are quantum dots containing surface ligands, the quantum dots include inorganic nanocrystals, and the quantum dots are bound on the surface of the inorganic nanocrystals. organic ligands. Wherein, the surface ligands include one or more of carboxyl surface ligands, amine surface ligands, sulfhydryl surface ligands and phosphine surface ligands. The surface ligands include one or more of short-chain or long-chain organics containing carboxyl groups, amine groups, sulfhydryl groups and phosphine groups, and the surface ligands are linked with the inorganic nanocrystal surface cations in the form of coordination bonds. For example, the surface ligand may be 9-carboxy-2-octylpyrene, trioctylphosphine, octadecylamine, octadecylthiol, and the like.

During the research, it was also found that the shedding of the surface ligands of the quantum dots is also one of the main reasons for the surface defects of the quantum dots. The detachment of the surface ligands of the quantum dots will produce a certain quenching effect on the excitons delocalized to the surface, resulting in a low fluorescence quantum yield. On the surface of quantum dot inorganic nanocrystals, surface dangling bonds generated by lattice defects can affect the optical properties of quantum dots. The surface properties of quantum dot inorganic nanocrystals have little effect on the quantum dots in the ground state, but have a huge impact on the performance of quantum dots in the excited state. The existence of defects on the surface of quantum dots will introduce defect state energy levels. When the defect energy level is higher than the excitons When the energy level is low, the defect energy level may trap electrons and holes, and then the excitons recombine through the defect state, and the energy is released in the form of light or heat. By coating the surface of quantum dots with surface ligands, lattice defects are eliminated, so that quantum dots have better fluorescence stability. Generally speaking, surface ligands with longer chains and greater steric hindrance are selected. .

In one embodiment of the present disclosure, the reducing organic substance is a reducing organic substance containing a coordinating group, and the reducing organic substance containing a coordinating group means that the molecular chain of the reducing organic substance is connected with ligands. The coordinating group can form a coordinate bond with the surface cations of the inorganic nanocrystal. Optionally, the surface ligands include one or more of carboxyl surface ligands, amine surface ligands, sulfhydryl surface ligands and phosphine surface ligands, that is, the coordinating group includes carboxyl groups , at least one of amine group, mercapto group and phosphine group. The carboxyl, amine, sulfhydryl, phosphine and other coordinating groups in the reducing organics described in this example can complement the lattice defects on the surface of the quantum dots due to the shedding of organic ligands, so as to avoid the resulting defect quenching Exciton out, reducing the problem of fluorescence quantum yield.

In one embodiment of the present disclosure, the coordination activity of the coordinating group and the quantum dot is stronger than the coordination activity of the surface ligand and the quantum dot. That is, the coordination activity of the selected reducing organics is stronger than that of the surface ligands, wherein the coordination activity refers to the ease with which the coordination group or the surface ligands form coordination bonds with the inorganic nanocrystals. degree or the degree of stability of the formation of coordination bonds. In the embodiments of the present disclosure, more stable coordination bonds can be formed on the surface of the inorganic nanocrystal by selecting a reducing organic compound with higher coordination activity than the surface ligand.

Generally, the order of coordination activity of the coordinating group is mercapto>amine>carboxyl>phosphine group, while for the same coordinating group, the order of coordination activity is short chain>long chain (with the reducibility of the coordinating group The longer the organic molecular chain, the lower the coordination activity of reducing organics containing coordinating groups). In one embodiment of the present disclosure, a reducing organic compound with higher coordination activity than the surface ligand is selected according to the above-mentioned order of the activity of the coordinating group.

In one embodiment of the present disclosure, the reducing organic compound is selected from one or more of ethanolamine, tributylphosphine, and polyethylene glycol amine. The ethanolamine, tributylphosphine and polyethylene glycol amine have reducibility and can eliminate the oxidation factors caused by environmental factors such as temperature or light, water and oxygen; at the same time, they also contain coordinating groups such as amine group and phosphine group respectively, The vacancy defects on the surface of the quantum dots due to ligand shedding can be complemented to avoid the reduction of the fluorescence quantum yield.

In the implementation process, according to different quantum dot dispersants, the reducing organic matter to be added can be selected to meet the requirement that it can be dispersed in an organic phase, an alcohol phase or an aqueous phase solvent. By selecting the reducing organic matter with good solubility in the dispersant, a uniform and stable quantum dot dispersion is formed, so that the reducing organic matter can move freely in the dispersion liquid, which is beneficial to realize the reducing organic matter as the surface through free movement The morphology of the ligands forms bonds with the surface of the quantum dot inorganic nanocrystals, thereby filling the defects caused by the exfoliation of the ligands on the surface in situ. For example, reducing organic compounds can be selected based on similar compatibility principles, for example, polar reducing organic compounds are selected for polar dispersants, and non-polar reducing organic compounds are selected for non-polar dispersing agents.

The dispersant described in this example is used to disperse quantum dots and reducing organic matter. The quantum dot dispersant includes an organic phase solvent, an alcohol phase solvent or an aqueous phase solvent. The organic phase solvent can be one or more of chloroform, toluene, n-hexane, cyclohexane, n-heptane, decane, n-octane, cycloheptane and dioxane; the alcoholic phase solvent can be methanol, One or more of ethanol, isopropanol, n-butanol, etc.; the aqueous phase solvent is deionized water.

The dispersing agent in this embodiment can be a non-polar solvent, such as dichloroethane, or a polar solvent, such as water.

In one embodiment of the present disclosure, the molar ratio of the reducing organic matter to the quantum dots is 0.5:1 to 2:1. That is, the dispersant is added in a molar ratio of m (reducing organic matter):m (quantum dots)=0.5:1 to 2:1. During the research, it was found that when the molar ratio is less than 0.5: At 1, the amount of reducing organic matter added is relatively small, and the effect of eliminating the oxidation factor in the dispersant and supplementing the surface ligands of the quantum dots is poor. According to the measured fluorescence quantum yield data, it will still be significantly attenuated; When the molar ratio is greater than 2:1, the addition of too much reducing organic matter will affect the form of the quantum dots in the dispersant, and may form an organic coating layer on the surface of the quantum dots, affecting the application of the quantum dots.

The molar ratio of the reducing organic matter to the quantum dots in this embodiment is 0.5:1 to 2:1, so that there is a certain degree of reducing environment on the surface of the quantum dots, so as to avoid the fluorescence performance of the quantum dots being affected by the temperature in the environment, At the same time, the presence of a certain proportion of surface ligands in the dispersant can form dynamic complementation defects with the organic ligands that fall off the surface of the quantum dots, reducing the effect of surface defects. Fluorescence instability issues.

The quantum dots are selected from the group II-VI compound quantum dots, the IV-VI group compound quantum dots, the III-V group compound quantum dots, the I-VI group compound quantum dots, that is, the quantum dots are selected from II- At least one of single-structure quantum dots and composite-structure quantum dots of dot VI, IV-VI, III-V, and I-VI compounds. In one embodiment of the present disclosure, the quantum dots are core-shell quantum dots. The core-shell quantum dot is a composite structure quantum dot, specifically by using a single-layer or multi-layer semiconductor material shell layer to coat the quantum dot crystal core, for example, the quantum dot crystal core is selected from CdSe, CdS, CdTe, CdSeTe, At least one of CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs, InZnP, InGaP, InGaN, CdZnSe and CdZnSe; the semiconductor material shell is selected from ZnSe At least one of , ZnS and ZnSeS, the quantum dots can be red quantum dots CdZnSe/ZnSe/ZnS or green quantum dots CdZnSe/ZnS. Among them, the lattice mismatch between the quantum dot core and the shell layer of the semiconductor material and the adjustment of the energy band deviation improve the performance of quantum dots. On the one hand, the small lattice mismatch between the core and shell is conducive to the formation of alloy transition at the layer-core-shell interface. Reduce the interface defects caused by lattice stress to form non-radiative recombination centers; on the other hand, the large energy band deviation between the core and the shell is conducive to the binding of electron and hole wave functions in the core, away from the non-radiative recombination centers of the shell surface states, Therefore, the fluorescence stability and optoelectronic properties of quantum dots can be improved by the growth of multi-shell layers.

In an embodiment of the present disclosure, in the quantum dot dispersion liquid, the concentration of the quantum dots is 1 mmol/mL to 100 mmol/mL, and the concentration of the quantum dots is 5 mmol/mL, 40 mmol/mL, 80 mmol/mL Wait.

Embodiments of the present disclosure provide a method for storing quantum dots, including:

The quantum dots, reducing organic matter, and dispersing agent are prepared into the quantum dot dispersion liquid as described above, and the quantum dots are stored.

The quantum dot preservation method described in this embodiment is to disperse the quantum dots in a dispersant containing reducing organic matter for preservation, and the reducing organic matter can eliminate and resist the generation of water, oxygen, light and other factors from the dispersant and the air. The oxidation reaction factor can effectively ensure the fluorescence stability of the quantum dots during the storage process, and solve the problem of the reduction of the fluorescence quantum yield caused by the influence of water, oxygen, light and other factors during the storage process of the purified quantum dots.

In one embodiment of the present disclosure, the storage temperature is 20-30°C. The quantum dot storage method described in this embodiment does not require low temperature (0° C.) storage, and long-term storage of quantum dots can also be achieved at room temperature. The conditions of the quantum dot storage method described in this embodiment are set to a normal temperature of 25° C., an ambient humidity of 50%, and an environment of natural light.

In one embodiment of the present disclosure, the method for storing quantum dots can realize long-term storage of quantum dots, and the storage time is 1 to 15 weeks. The quantum dots described in this example still maintain high fluorescence quantum efficiency after being stored for 15 weeks.

In the quantum dot sample preservation method, by adding an organic substance with weak reducibility to the purified quantum dot dispersant, the oxidation reaction factors generated by factors such as water, oxygen, light and the like from the dispersant and the air can be eliminated and resisted, At the same time, the added reducing organic matter is dissociated in the dispersant, which can fill in the defects caused by the shedding of weak ligands on the surface of the quantum dots in time, so as to ensure that the fluorescence quantum efficiency of the quantum dots does not change for a long time in the dispersant.

The technical solutions of the present disclosure will be described below through specific examples and comparative examples.

In Example 1 of the present disclosure, the dispersant is chloroform, and 5 mL of 50 mmol/mL red quantum dots CdZnSe/ZnSe/ZnS (PL=625 nm, FWHM=22 nm) is placed in a white transparent glass bottle, and the organic ligands are oleic acid, Oleylamine, the added reducing organic matter is 150 mmol tributylphosphine, and the fluorescence intensity changes of the samples are monitored under the storage conditions of room temperature 25° C., 50% ambient humidity and natural light.

The present disclosure provides a pair of Example 1, which is different from Example 1 in that no reducing organic tributylphosphine is added to Comparative Example 1, and the rest are the same.

As can be seen from Table 1, from the obtained data, the fluorescence quantum yield of the quantum dots of Comparative Example 1 decreases with the prolongation of the storage time, and the fluorescence intensity decreases continuously, from the initial fluorescence quantum yield of 85% to a stable 38%. . The fluorescence quantum yield of the addition of tributylphosphine decreased slightly to 80% in the early stage, and remained at a normal level with time. It can be seen that the water, oxygen and light in the normal temperature environment produce oxidation factors, which cause the fluorescence intensity of quantum dots to gradually decay, while the quantum dot fluorescence intensity of the quantum dot dispersion liquid with the addition of reducing organic matter is maintained better. It can be seen that the added reduction Sexual organic compounds play a role in protecting the fluorescence stability of quantum dots.

In Example 2 of the present disclosure, the green quantum dots CdZnSe/ZnS (PL=535nm, FWHM=24nm) dispersed in 5mL of ethanol solvent were selected, the concentration was 30mmol/mL, and the organic ligand on the surface of the quantum dots was 6-mercaptohexanol. 100 mmol of ethanolamine as reducing organics. Monitor the fluorescence stability of quantum dot samples.

The present disclosure provides a pair of Example 2, which is different from Example 2 in that, in Comparative Example 2, no reducing organic ethanolamine is added, and the rest are the same.

As shown in Table 1, the fluorescence quantum yield of the quantum dots of Comparative Example 2 decreased from the initial 60% to 15%, while the final fluorescence quantum yield of the quantum dots added with ethanolamine in Example 2 was as high as 55%.

In Example 3 of the present disclosure, deionized water was used as a dispersant to prepare 5 mL of CdSe/CdS/ZnS water-soluble quantum dots with 10 mmol/mL diethylenetriamine as the surface organic ligand, and 30 mmol of polyethylene glycol amine was added as a reducing agent. Organic matter, stored at 0°C in a refrigerator, and monitored the fluorescence stability of quantum dot samples.

The present disclosure provides a pair of Example 3, the difference from Example 3 is that no reducing organic polyethylene glycol amine is added in Comparative Example 3, and the rest are the same.

In Comparative Example 3, 5 mL of 10 mmol/mL diethylenetriamine was selected as the CdSe/CdS/ZnS water-soluble quantum dots with surface organic ligands as the monitoring object. Due to the particularity of the aqueous solution, the problem of aggregation and sedimentation is likely to occur at room temperature. Therefore, it was stored in a low temperature refrigerator at 0°C. As shown in Table 1, the initial fluorescence quantum yield of the water-phase quantum dots in Comparative Example 3 was 33%. After the test cycle changes, the fluorescence intensity quenching of the comparison quantum dots was more obvious, and the final test value was 5%. In contrast, in Example 3, the fluorescence quantum yield of the quantum dot aqueous phase to which 30 mmol of polyethylene glycol amine was added was 26%.

In Examples 1 to 3 and Comparative Examples 1 to 3, the monitoring of the fluorescence stability of the quantum dot dispersion was carried out according to the following procedure:

(1), respectively select 10 groups of quantum dot solutions dispersed in organic phase, alcohol phase and aqueous solvent under parallel conditions;

(2) The conditions for sample preservation are set to normal temperature 25°C or 0°C, 50% ambient humidity, and natural light environment;

(3) The fluorescence quantum yield test setting standard is periodic sampling to monitor the fluorescence quantum yield of the sample, and the test interval is 1 week, 1 week, 2 weeks, 3 weeks, 4 weeks, and 4 weeks. Three groups of samples were randomly selected from the parallel samples for determination.

Table 1 is the fluorescence quantum yield monitoring data of Examples 1-3 and Comparative Examples 1-3 provided by the present disclosure. As can be seen from Table 1, the storage method of quantum dots described in the present disclosure can effectively ensure the fluorescence stability of quantum dots for long-term storage.

Table 1: Example and Comparative Example Fluorescence Quantum Yield Monitoring Data Provided in the Disclosure

The quantum dot dispersion described in the present disclosure contains organic substances with weak reducibility. On the one hand, it can eliminate the oxidation reaction factors introduced by factors such as temperature, illumination, and water and oxygen environment, avoid defects on the surface of the inorganic nanocrystals of quantum dots, and reduce the fluorescence quantum yield. On the other hand, the added reducing organic matter can act as a ligand on the surface of the quantum dot, and is in a free state in the dispersant. When the ligand on the surface of the quantum dot falls off due to the failure of the weak coordination bond, the surface of the quantum dot is replenished in time. defects, maintaining the fluorescence stability of quantum dots.

It should be understood that the application of the present disclosure is not limited to the above examples, and those of ordinary skill in the art can make improvements or transformations according to the above descriptions, and all such improvements and transformations should fall within the protection scope of the appended claims of the present disclosure.

Claims

A quantum dot dispersion liquid, comprising: a dispersant, quantum dots and reducing organic matter.
The quantum dot dispersion liquid according to claim 1, wherein the reducing organic substance is selected from one or more of alcohols, phenols, aldehydes, organic amines, organic phosphorus, and olefins.
The quantum dot dispersion liquid according to claim 2, wherein the reducing organic substance is selected from one or more of ethanolamine, tributylphosphine, and polyethylene glycol amine.
The quantum dot dispersion liquid according to claim 1, wherein the quantum dots are quantum dots containing surface ligands.
The quantum dot dispersion liquid according to claim 4, wherein the surface ligands comprise one or more of carboxyl surface ligands, amine surface ligands, thiol surface ligands and phosphine surface ligands.
The quantum dot dispersion liquid according to claim 5, wherein the reducing organic substance is a reducing organic substance containing a coordinating group.
The quantum dot dispersion liquid according to claim 6, wherein the coordinating group comprises at least one of a carboxyl group, an amine group, a mercapto group, and a phosphine group.
The quantum dot dispersion liquid according to claim 7, wherein the coordination activity of the coordinating group and the quantum dot is stronger than that of the surface ligand and the quantum dot.
The quantum dot dispersion liquid according to claim 1, wherein the dispersing agent comprises chloroform, toluene, n-hexane, cyclohexane, n-heptane, decane, n-octane, cycloheptane, dioxane, One or more of water, methanol, ethanol, isopropanol, n-butanol.
The quantum dot dispersion liquid according to claim 9, wherein the molar ratio of the reducing organic substance to the quantum dots is 0.5:1 to 2:1.
The quantum dot dispersion liquid according to claim 10, wherein, in the quantum dot dispersion liquid, the concentration of the quantum dots is 1 mmol/mL to 100 mmol/mL.
The quantum dot dispersion liquid according to claim 11, wherein the quantum dots are selected from the group consisting of II-VI compound quantum dots, IV-VI compound quantum dots, III-V compound quantum dots, and I-VI compound quantum dots one or more of the points.
The quantum dot dispersion liquid according to claim 12, wherein the quantum dots are core-shell quantum dots formed by using a single-layer or multi-layer semiconductor material shell layer to coat the quantum dot crystal nucleus.
The quantum dot dispersion liquid according to claim 13, wherein the quantum dot crystal nucleus is selected from the group consisting of CdSe, CdS, CdTe, CdSeTe, CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, At least one of GaP, GaAs, InP, InAs, InZnP, InGaP, InGaN, CdZnSe, and CdZnSe.
The quantum dot dispersion liquid of claim 13, wherein the semiconductor material shell layer is selected from at least one of ZnSe, ZnS and ZnSeS.
The quantum dot dispersion liquid according to claim 13, wherein the quantum dots are red quantum dots CdZnSe/ZnSe/ZnS or green quantum dots CdZnSe/ZnS.
A quantum dot preservation method, comprising:

The quantum dots, reducing organic matter, and dispersing agent are prepared into the quantum dot dispersion liquid according to any one of claims 1 to 12, and the quantum dots are stored.
The quantum dot storage method according to claim 17, wherein the storage temperature is 20-30°C.