ZnS nanocrystal as well as preparation method and application thereof

Abstract

The invention discloses a ZnS nanocrystal and a preparation method and application thereof, and the preparation method of the ZnS nanocrystal comprises the following steps: mixing a zinc source and a first solvent to obtain a first precursor solution; mixing a sulfur source and a second solvent to obtain a second precursor solution; and introducing the first precursor solution and the second precursor solution into a reaction pipeline, so that the first precursor solution and the second precursor solution are mixed in the reaction pipeline and react in a flowing state to obtain the ZnS nanocrystal. According to the preparation method for continuously and homogeneously synthesizing the high-refractive-index material ZnS (zinc sulfide), the continuous and stable reaction environment is provided by accurately controlling the reaction atmosphere, such as pressure, temperature, flow and reaction chamber environment, the mass transfer and the transfer speed of the reaction are accelerated by the micro reaction chamber, the reaction can be instantaneously and homogeneously carried out, and the reaction time is shortened. The prepared ZnS (zinc sulfide) has the advantages of uniform size distribution, controllable particle size, good batch repeatability and the like.

Description

Technical Field

[0001] This invention belongs to the field of optical materials technology, specifically relating to a ZnS nanocrystal, its preparation method, and its application. Background Technology

[0002] High-refractive-index materials can enhance the interaction between light waves and matter, improve the light absorption rate of materials, reduce optical losses, enable long-distance waveguide transmission, and improve the efficiency of optical devices. Doping high-refractive-index materials into thin films can alter the interaction between light waves and the film, increasing the effective refractive index of the material. These materials are widely used in AR displays, high-end optical systems, quantum optics, healthcare, and sensing, and are particularly crucial in compact, low-loss optical devices. They can effectively regulate light output efficiency, meeting the stringent requirements of modern optical devices for thinness, high luminous efficiency, and environmental adaptability. Adding high-refractive-index nanocrystals, such as zinc sulfide, zirconium oxide, and titanium oxide, to optical film coatings and microdisplay encapsulation adhesives is one of the effective ways to adjust the refractive index of optical films and improve light output.

[0003] In particular, ZnS (zinc sulfide), as an important optical material, has a high refractive index, which can improve the optical performance of optical films, such as enhancing the refraction and focusing ability of light. It also has good high transmittance and low light absorption, enabling it to effectively transmit light and reduce energy loss in optical films. For example, patent 201210293596.X prepared high-refractive-index ZnS nanocrystals using a solvothermal reaction method, and patent 202211422357.X also reported the preparation of ZnS nanocrystals for lubricating greases.

[0004] Existing methods for preparing high-refractive-index nanomaterials such as ZnS (zinc sulfide) typically employ high-temperature calcination, high-temperature microwave methods, sol-gel methods, hydrothermal methods, and solvothermal methods. However, these methods often suffer from poor batch stability, uneven particle size distribution, low yield, and long reaction times. When mixed into a doped system, the ZnS exhibits uneven dispersion and difficulty in dispersion due to inhomogeneous particle size and unsuitable particle size, sometimes even leading to sedimentation. These problems are particularly pronounced in heavily doped systems with high solid content requirements, resulting in uncontrollable refractive index in the doped system and severely limiting the application of high-refractive-index materials in optical films (such as brightness enhancement films) and microdisplays. Summary of the Invention

[0005] The purpose of this invention is to provide a ZnS nanocrystal, its preparation method and application, which has advantages such as uniform size distribution, controllable particle size and good batch repeatability.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A method for preparing ZnS nanocrystals, the method comprising the following steps:

[0008] The zinc source and the first solvent are mixed to obtain the first precursor solution;

[0009] The sulfur source and the second solvent are mixed to obtain the second precursor solution;

[0010] The first precursor solution and the second precursor solution are introduced into the reaction channel to mix and react in a flowing state, thereby obtaining ZnS nanocrystals.

[0011] In one or more embodiments of the present invention, the flow rate of the mixture of the first precursor solution and the second precursor solution in the reaction pipeline is 0.5 ml / min-10 ml / min, the reaction temperature is 90℃-200℃, the reaction time is 16s-320s, and the reaction pressure is 0.5 bar-3 bar.

[0012] In one or more embodiments of the present invention, the zinc source is one or more selected from zinc acetate, zinc nitrate, zinc carbonate, zinc sulfate, etc.; and / or,

[0013] The sulfur source is one or more selected from thiourea, sodium sulfide, and thioacetamide; and / or,

[0014] The first solvent is one or more of dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters; and / or,

[0015] The second solvent is one or more of the following: dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters.

[0016] In one or more embodiments of the present invention, the concentration of the first precursor solution is 0.01 mol / L to 0.25 mol / L; and / or,

[0017] The concentration of the second precursor solution is 0.01 mol / L to 0.25 mol / L.

[0018] In one or more embodiments of the present invention, the method for preparing the ZnS nanocrystals further includes the following steps:

[0019] Zinc sources are divided into a first zinc source and a second zinc source in a mass ratio of 1:0.3 to 1:3. The first zinc source is mixed with a first solvent to obtain a first zinc source precursor solution. The second zinc source is mixed with the first solvent to obtain a second zinc source precursor solution.

[0020] The first zinc source precursor solution and the second precursor solution are introduced into the first reaction pipe, so that the first zinc source precursor solution and the second precursor solution are mixed in the first reaction pipe and reacted in a flowing state to obtain an intermediate product.

[0021] The intermediate product and the second zinc source precursor solution are introduced into the second reaction channel, where they are mixed and reacted in a flowing state to obtain ZnS nanocrystals.

[0022] In one or more embodiments of the present invention, the method for preparing the ZnS nanocrystals further includes the following steps:

[0023] The first precursor solution and the second precursor solution are introduced into the first reaction channel to mix and react in a flowing state to obtain ZnS nanocrystals.

[0024] ZnS nanocrystals and dithiopentane ligands are introduced into a second reaction channel to allow them to react in a flowing state, resulting in surface-modified ZnS nanocrystals.

[0025] In one or more embodiments of the present invention, the method for preparing the ZnS nanocrystals further includes the following steps:

[0026] The dithiopentane ligand and the first precursor solution were mixed to obtain the first precursor mixture.

[0027] The first precursor mixture and the second precursor solution are introduced into a reaction channel to mix and react in a flowing state, thereby obtaining surface-modified ZnS nanocrystals.

[0028] In one or more embodiments of the present invention, the molar ratio of the ZnS nanocrystals to the dithiopentane ligand is (5-15):1; and / or,

[0029] The dithiopentane ligand is , , , , One or more of the following; and / or,

[0030] The reaction conditions for the ZnS nanocrystals and dithiopentane ligand, or the reaction conditions for the first precursor mixture and the second precursor solution, are: reaction temperature 100℃-200℃, reaction time 0.5h-3h, and reaction pressure 0.5bar-3bar.

[0031] Another specific embodiment of the present invention provides the following technical solution:

[0032] A ZnS nanocrystal, wherein the ZnS nanocrystal is prepared by the above-described method for preparing ZnS nanocrystals, and the average particle size of the ZnS nanocrystal is 50 nm-90 nm.

[0033] Another specific embodiment of the present invention provides the following technical solution:

[0034] An application of ZnS nanocrystals in optical films.

[0035] Compared with existing technologies, this invention employs a continuous flow homogeneous synthesis method for preparing high-refractive-index material ZnS (zinc sulfide). This method provides a continuous and stable reaction environment by precisely controlling the reaction atmosphere, such as pressure, temperature, flow rate, and reaction chamber environment. The micro-reaction chamber accelerates the mass transfer and rate of the reaction, and the reaction can proceed in a homogeneous manner instantaneously. The prepared ZnS (zinc sulfide) has advantages such as uniform size distribution, controllable particle size, and good batch repeatability. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of the continuous liquid-phase reactor used in the preparation method of ZnS nanocrystals in one embodiment of the present invention. Figure 1 ;

[0038] Figure 2 This is a schematic diagram of the structure of the continuous liquid-phase reactor used in the preparation method of ZnS nanocrystals in one embodiment of the present invention. Figure 2 ;

[0039] Figure 3 The image shows the dispersion of ZnS nanocrystals without and with dithiopentane ligands in octane in one embodiment of the present invention.

[0040] Explanation of key figure labels:

[0041] 1. First pipeline; 2. Second pipeline; 3. Reaction pipeline; 4. Third pipeline; 5. Second reaction pipeline; 6. First reaction pipeline. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0043] In heavily doped systems, the size and particle size distribution of high-refractive-index nanocrystals significantly influence their stability within the doped system and their ability to regulate the refractive index. Excessively large particle sizes can lead to an imbalance between gravity and buoyancy, even causing sedimentation. Non-uniform particle size distribution results in non-uniform refractive index in the doped system. Surface defect states also have a crucial impact on the ease of dispersion of nanocrystals within the doped system. Therefore, nanoparticles must possess a uniform particle size distribution, controllable particle size, and surface states with good compatibility with the doped system to achieve uniform and stable doping and effectively regulate the refractive index of the doped system.

[0044] This invention provides a continuous and stable reaction environment through precise control of the reaction atmosphere, such as pressure, temperature, flow rate, and reaction chamber environment. The micro-cavity size of the reaction chamber enables the microreactor to have extremely high mixing efficiency (achieving complete radial mixing within milliseconds) and extremely strong heat transfer capacity (heat transfer coefficient can reach 25,000 W / (m²)). 2 With its extremely narrow residence time distribution (approximately close to plug flow), the reaction can proceed homogeneously in an instant, avoiding secondary reactions and inconsistent reaction times in the reactor. The resulting high-refractive-index ZnS nanocrystals have advantages such as uniform size distribution, controllable particle size, and good batch repeatability.

[0045] The ZnS nanocrystalline material is dispersed in the doped system. The uniform particle size distribution ensures the uniformity of the refractive index of the doped system, and the appropriate particle size ensures that the gravity and buoyancy of the nanocrystals are balanced in the doped system, avoiding problems such as stratification and sedimentation. Moreover, compared with materials prepared by traditional methods, the surface defect states are greatly reduced, and the material has stronger compatibility with the doped system and is easier to disperse in the doped system.

[0046] A specific embodiment of the present invention provides a method for preparing ZnS nanocrystals, comprising the following steps:

[0047] Step 1: Mix the zinc source and the first solvent to obtain the first precursor solution.

[0048] Specifically, the zinc source is one or more of zinc acetate, zinc nitrate, zinc carbonate, and zinc sulfate, and the first solvent is one or more of dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters. The concentration of the first precursor solution is 0.01 mol / L to 0.25 mol / L, preferably 0.04 mol / L to 0.25 mol / L, and can specifically be 0.04 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, or 0.25 mol / L.

[0049] Step 2: Mix the sulfur source and the second solvent to obtain the second precursor solution.

[0050] Specifically, the sulfur source is one or more of thiourea, sodium sulfide, and thioacetamide, and the second solvent is one or more of dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters. The concentration of the second precursor is 0.01 mol / L to 0.25 mol / L, preferably 0.05 mol / L to 0.25 mol / L, and can specifically be 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, or 0.25 mol / L.

[0051] Step 3: The first precursor solution and the second precursor solution are introduced into the reaction pipe to mix and react in a flowing state to obtain ZnS nanocrystals.

[0052] Specifically, the continuous liquid-phase reactor used in this step is such as... Figure 1 As shown, it includes a first container and a second container. The first container is connected to a first pipe 1, and the second container is connected to a second pipe 2. The first pipe 1 and the second pipe 2 are jointly connected to a reaction pipe 3. The first container stores a first precursor solution, and the second container stores a second precursor solution.

[0053] The first precursor solution is introduced into the reaction pipe 3 through the first pipe 1 at a rate of 0.5 ml / min-10 ml / min, while the second precursor solution is introduced into the reaction pipe 3 through the second pipe 2 at a rate of 0.5 ml / min-10 ml / min. The first and second precursor solutions are mixed in the reaction pipe 3 and flow at a rate of 0.5 ml / min-10 ml / min. The reaction is carried out at a reaction temperature of 90℃-200℃ and a reaction pressure of 0.5 bar-3 bar for a time of 16 s-320 s. The reaction product flows out of the reaction pipe 3 and is collected, centrifuged, and washed in methanol.

[0054] Furthermore, in combination Figure 2 To better control the uniformity of particle size distribution and particle size, in step 3, the zinc source can be first divided into a first zinc source and a second zinc source in a mass ratio of 1:0.3-1:3. The first zinc source and the first solvent are mixed to obtain a first zinc source precursor solution; the second zinc source and the first solvent are mixed to obtain a second zinc source precursor solution; then the first zinc source precursor solution and the second precursor solution are introduced into the first reaction tube 6, allowing them to mix and react in a flowing state to obtain an intermediate product; then the intermediate product and the second zinc source precursor solution are introduced into the second reaction tube 5, allowing them to mix and react in a flowing state. In this method, the temperature, flow rate, pressure, and other reaction atmosphere of the first reaction tube 6 and the second reaction tube 5 can be controlled separately, thereby obtaining ZnS nanocrystals with more uniform particle size distribution and better controllability of particle size.

[0055] Step 4: Modify ZnS nanocrystals with dithiopentane ligands.

[0056] Specifically, the dithiopentane ligand is , , , , One or more of them.

[0057] The introduction of disulfide pentane ligands allows for the reaction with matrices such as epoxy resins under ultraviolet light initiation to form three-dimensional network polymer materials, making ZnS nanocrystals more stable in the matrix. Furthermore, most traditional ligands are low-refractive-index alkanes, which significantly reduce the refractive index of the nanocrystals after modification. The sulfur element in the introduced disulfide group can further improve the refractive index of the modified nanocrystals.

[0058] Furthermore, the specific method for modifying ZnS nanocrystals with dithiopentane ligands can be as follows: Dithiopentane ligands and a first precursor solution are mixed to obtain a first precursor mixture; the first precursor mixture and a second precursor solution are then introduced into a reaction pipe 3, allowing them to mix and react in a flowing state within the reaction pipe 3 to obtain surface-modified ZnS nanocrystals. This method simultaneously forms the reaction product ZnS nanocrystals and performs surface modification on the product, significantly shortening the modification time and improving the modification effect.

[0059] Furthermore, the specific method for modifying ZnS nanocrystals with dithiopentane ligands can also be as follows: First precursor solution and second precursor solution are introduced into first reaction pipe 6, allowing them to mix and react in a flowing state to obtain ZnS nanocrystals; ZnS nanocrystals and dithiopentane ligands are introduced into second reaction pipe 5, allowing them to react in a flowing state to obtain surface-modified ZnS nanocrystals.

[0060] In this method, dithiopentane ligands are dissolved in xylene or DMF at a ratio of 1:50~100 to modify ZnS products in situ. This achieves the goals of shortening the modification time, avoiding contact with the external environment, and simplifying the reaction equipment. While forming more stable nanocrystals with more uniform surface states, the dithiopentane ligands, containing sulfur (S) elements, have a high refractive index. This modification further improves the refractive index and dispersibility of ZnS nanocrystals, resulting in ZnS nanocrystals with better modification effects. This method has significant advantages in the industrial application of high refractive index nanocrystals. The continuous batch homogeneous preparation of high refractive index nanocrystals using this method has important application value for realizing the industrialization and domestic substitution of high refractive index nanocrystals.

[0061] Furthermore, the molar ratio of ZnS nanocrystals to dithiopentane ligands is (5-15):1, the reaction temperature is 100℃-200℃, the reaction time is 0.5h-3h, and the reaction pressure is 0.5bar-3bar.

[0062] The present invention will be further described in detail below with reference to specific embodiments.

[0063] Example 1

[0064] The preparation method of ZnS nanocrystals in this embodiment is as follows:

[0065] (1) Preparation of solution: Under a nitrogen atmosphere, weigh 9 mmol of zinc acetate and 8 mmol of thiourea. Dissolve zinc acetate in 150 ml of DMF (dimethylformamide) to obtain the first precursor solution, and dissolve thiourea in 150 ml of DMF (dimethylformamide) to obtain the second precursor solution. Seal and stir to completely dissolve the precursor solution, and use it as the reaction source material.

[0066] (2) The first precursor solution and the second precursor solution of the reaction source material are respectively introduced into a pre-set circuit, such as... Figure 1 The first pipe 1 and the second pipe 2 of the continuous liquid phase reactor are shown. Then, the mixture is introduced into the reaction pipe 3. The reaction is carried out rapidly and uniformly at a temperature of 150°C, a flow rate of 5 ml / min, and a pressure of 2.0 bar for 32 s. The synthesized ZnS nanocrystals are collected from the reaction pipe 3.

[0067] (3) The reaction product was collected in methanol solution, precipitated and centrifuged to obtain solid ZnS nanocrystals. The solid nanocrystals were washed, centrifuged and precipitated with ethyl acetate to obtain pure ZnS nanocrystals.

[0068] (4) Particle size test results show that the obtained ZnS nanocrystals have a size of 50-60 nm and a uniform particle size distribution.

[0069] Example 2

[0070] The preparation method of ZnS nanocrystals in this embodiment is as follows:

[0071] (1) Preparation of solution: Under a nitrogen atmosphere, weigh 9 mmol of zinc acetate and 8 mmol of thiourea. Dissolve zinc acetate in 150 ml of DMF (dimethylformamide) to obtain the first precursor solution, and dissolve thiourea in 150 ml of DMF (dimethylformamide) to obtain the second precursor solution. Seal and stir to completely dissolve the precursor solution, and use it as the reaction source material.

[0072] (2) The zinc source and sulfur source of the reaction materials are respectively introduced into the pre-set circuit, such as... Figure 1 The first pipe 1 and the second pipe 2 of the continuous liquid phase reactor are shown. Then, the mixture is introduced into the reaction pipe 3. The mixture is rapidly and uniformly reacted at a temperature of 120°C, a flow rate of 1 ml / min, and a pressure of 0.5 bar for 162 s. The synthesized ZnS nanocrystals are collected from the reaction pipe 3.

[0073] (3) The reaction product was collected in methanol solution, precipitated and centrifuged to obtain solid ZnS nanocrystals. The solid nanocrystals were washed, centrifuged and precipitated with ethyl acetate to obtain pure ZnS nanocrystals.

[0074] (4) Particle size test results show that the obtained ZnS nanocrystals have a size of 80-90 nm and a uniform particle size distribution.

[0075] Example 3

[0076] The preparation method of ZnS nanocrystals in this embodiment is as follows:

[0077] (1) Solution preparation: Under vacuum or nitrogen atmosphere, weigh 9 mmol zinc acetate and 8 mmol thiourea. Dissolve zinc acetate in 150 ml DMF (dimethylformamide) to obtain the first precursor solution. Divide the first precursor into a first zinc source precursor solution (containing 1 / 3 mass ratio of zinc source) and a second zinc source precursor solution (containing 2 / 3 mass ratio of zinc source). Dissolve thiourea in 150 ml DMF (dimethylformamide) to obtain the second precursor solution. Seal and stir to completely dissolve the precursor solution, which will be used as the reaction source material.

[0078] (2) The reaction sulfur source and the first zinc source precursor solution with a 1 / 3 ratio of zinc source are respectively passed into a pre-set circuit, such as... Figure 2 The reaction pipes 1 and 2 of the continuous liquid phase reactor are shown. Then, the mixture is introduced into the first reaction pipe 6 for mixing. The reaction is carried out rapidly and uniformly for 32 seconds at a temperature of 150°C, a flow rate of 5 ml / min, and a pressure of 2.0 bar to synthesize ZnS nanocrystalline intermediate products.

[0079] (3) The ZnS nanocrystal intermediate obtained in step (2) is used as the second reaction source and flows into the second reaction pipe 5 from the first reaction pipe 6. At the same time, the second zinc source precursor solution with another 2 / 3 ratio of zinc source flows into the second reaction pipe 5 from the third pipe 4 and mixes with the ZnS nanocrystal intermediate. The reaction is carried out at 150°C, at a flow rate of 5 ml / min and a pressure of 2.0 bar for 32 s. The synthesized ZnS nanocrystals flow out from the second reaction pipe 5 and are collected.

[0080] (4) The reaction product was collected in methanol solution, precipitated and centrifuged to obtain solid ZnS nanocrystals. The solid nanocrystals were washed, centrifuged and precipitated with ethyl acetate to obtain pure ZnS nanocrystals.

[0081] (5) Particle size test results show that the obtained ZnS nanocrystals have a size of 50-55 nm and a more uniform particle size distribution.

[0082] Example 4

[0083] The preparation method of ZnS nanocrystals in this embodiment is as follows:

[0084] (1) Preparation of solution: Under a nitrogen atmosphere, weigh 9 mmol of zinc acetate and 8 mmol of thiourea. Dissolve zinc acetate in 150 ml of DMF (dimethylformamide) to obtain the first precursor solution, and dissolve thiourea in 150 ml of DMF (dimethylformamide) to obtain the second precursor solution. Seal and stir to completely dissolve the precursor solution, and use it as the reaction source material.

[0085] (2) The first precursor solution and the second precursor solution of the reaction source material are respectively introduced into a pre-set circuit, such as... Figure 2 The first pipe 1 and the second pipe 2 of the continuous liquid phase reactor are shown. Then, the mixture is introduced into the first reaction pipe 6. The mixture is rapidly and uniformly reacted at a temperature of 150°C, a flow rate of 5 ml / min, and a pressure of 2.0 bar for 32 seconds. The synthesized ZnS nanocrystals flow out from the first reaction pipe 6.

[0086] (3) The synthesized ZnS nanocrystals are introduced into the second reaction pipe 5 through the first reaction pipe 6, while 1,2-dithiopentane-3-pentanoic acid ( The ZnS nanocrystals were introduced into the second reaction pipe 5 at a rate of 3 ml / min from the third pipe 4. The ratio of ZnS nanocrystals to dithiopentane ligands was 10:1. In-situ modification was carried out at 150 °C and 1.3 bar pressure. The reaction product flowed out from the second reaction pipe 5 and was collected.

[0087] (4) The reaction product was collected in methanol solution, precipitated and centrifuged to obtain solid ZnS nanocrystals. The solid nanocrystals were washed, centrifuged and precipitated with ethyl acetate to obtain surface-modified ZnS nanocrystals.

[0088] (5) Particle size test showed that after modification with dithiopentane ligand, the particle size of ZnS nanocrystals increased from the original 50nm-60nm to 55nm-65nm, indicating that the dithiopentane ligand effectively modified and coated the ZnS nanocrystals, and the modification effect was uniform.

[0089] After modification with dithiopentane ligands, the surface activity of ZnS nanocrystals is greatly improved. When dispersed in organic solvents such as octane, the ZnS modified with dithiopentane ligands is more easily dispersed in these solvents. Figure 3 As shown, (a) and (b) are the dispersion of ZnS nanocrystals without dithiopentane ligand modification (Example 1) and ZnS nanocrystals modified with dithiopentane ligand modification (Example 4) in octane, respectively. Figure 3 (a) It can be seen that ZnS without dithiopentane ligand modification cannot form a clear solution when dispersed in octane, while Figure 3 (b) The ZnS nanocrystals modified with dithiopentane ligands can form a clear solution when dispersed in octane, indicating that the ZnS nanocrystals modified with dithiopentane ligands can be completely dispersed in octane.

[0090] The refractive index of ZnS nanocrystalline materials was further improved after modification with dithiopentane ligands, with the refractive index in the blue-green light band increasing to 2.38-2.45. This indicates that the modified ZnS nanocrystalline materials are expected to significantly improve the optical performance of optical film coatings and UV adhesives for displays, and increase light output efficiency.

[0091] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0092] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing ZnS nanocrystals, characterized in that, The preparation method of the ZnS nanocrystals includes the following steps: The zinc source and the first solvent are mixed to obtain the first precursor solution; The sulfur source and the second solvent are mixed to obtain the second precursor solution; The first precursor solution and the second precursor solution are introduced into the reaction channel to mix and react in a flowing state, thereby obtaining ZnS nanocrystals.

2. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The flow rate of the mixture of the first precursor solution and the second precursor solution in the reaction pipeline is 0.5 ml / min-10 ml / min, the reaction temperature is 90℃-200℃, the reaction time is 16s-320s, and the reaction pressure is 0.5 bar-3 bar.

3. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The zinc source is one or more of zinc acetate, zinc nitrate, zinc carbonate, zinc sulfate, etc.; and / or, The sulfur source is one or more selected from thiourea, sodium sulfide, and thioacetamide; and / or, The first solvent is one or more of dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters; and / or, The second solvent is one or more of the following: dimethylformamide, dimethylacetamide, anhydrous ethanol, chloroform, propanol, butanol, heptanol, decanol, ethylene glycol, propylene glycol, propylene glycol ethers, and propylene glycol esters.

4. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The concentration of the first precursor solution is 0.01 mol / L to 0.25 mol / L; and / or, The concentration of the second precursor solution is 0.01 mol / L to 0.25 mol / L.

5. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The method for preparing the ZnS nanocrystals further includes the following steps: The zinc source is divided into a first zinc source and a second zinc source in a mass ratio of 1:0.3 to 1:

3. The first zinc source and the first solvent are mixed to obtain a first zinc source precursor solution. The second zinc source and the first solvent are mixed to obtain a second zinc source precursor solution; The first zinc source precursor solution and the second precursor solution are introduced into the first reaction pipe, so that the first zinc source precursor solution and the second precursor solution are mixed in the first reaction pipe and reacted in a flowing state to obtain an intermediate product. The intermediate product and the second zinc source precursor solution are introduced into the second reaction channel, where they are mixed and reacted in a flowing state to obtain ZnS nanocrystals.

6. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The method for preparing the ZnS nanocrystals further includes the following steps: The first precursor solution and the second precursor solution are introduced into the first reaction channel to mix and react in a flowing state to obtain ZnS nanocrystals. ZnS nanocrystals and dithiopentane ligands are introduced into a second reaction channel to allow them to react in a flowing state, resulting in surface-modified ZnS nanocrystals.

7. The method for preparing ZnS nanocrystals according to claim 1, characterized in that, The method for preparing the ZnS nanocrystals further includes the following steps: The dithiopentane ligand and the first precursor solution were mixed to obtain the first precursor mixture. The first precursor mixture and the second precursor solution are introduced into a reaction channel to mix and react in a flowing state, thereby obtaining surface-modified ZnS nanocrystals.

8. The method for preparing ZnS nanocrystals according to any one of claims 6 or 7, characterized in that, The molar ratio of the ZnS nanocrystals to the dithiopentane ligand is (5-15):1; and / or, The dithiopentane ligand is , , , , One or more of the following; and / or, The reaction conditions for the ZnS nanocrystals and dithiopentane ligand, or the reaction conditions for the first precursor mixture and the second precursor solution, are: reaction temperature 100℃-200℃, reaction time 0.5h-3h, and reaction pressure 0.5bar-3bar.

9. A ZnS nanocrystal, characterized in that, The ZnS nanocrystals are prepared by the ZnS nanocrystal preparation method according to claim 1, and the average particle size of the ZnS nanocrystals is 50nm-90nm.

10. The application of the ZnS nanocrystals as described in claim 9 in an optical film.

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