Dark blue-emitting InP / ZnS blue light quantum dot and preparation method thereof

Abstract

The invention provides a dark blue-emitting InP / ZnS blue light quantum dot and a preparation method thereof, and belongs to the technical field of luminescent materials.The preparation method comprises the steps that at the first temperature, an indium precursor and a zinc precursor are placed in a three-necked flask, then pre-air-exhaust treatment is conducted, a coordination solvent is added into the flask, and an indium precursor mixed solution is prepared; raising the temperature to a second temperature, and injecting a phosphorus source into the indium precursor mixed solution to obtain an indium phosphide mixed solution; the sulfur precursor is injected into the indium phosphide mixed solution, the temperature is increased to a third temperature, the indium phosphide quantum dot of a core-shell structure is generated through a reaction, the dark blue-emitting InP / ZnS blue light quantum dot is obtained after separation and purification, and the core-shell structure formed on the basis of the quantum dot comprises an indium phosphide crystal nucleus not doped with elements and an external zinc sulfide shell layer. The deep blue light-emitting indium phosphide blue light quantum dot prepared by the invention is excellent in optical performance, the light-emitting wavelength is tunable in the range of 438-468 nm, the preparation process is simple, the condition is mild, and heavy metals and toxic elements are not contained.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and in particular to a deep blue emitting InP / ZnS blue light quantum dot and a preparation method thereof. Background Art

[0002] Colloidal quantum dots (QDs) are a new type of fluorescent material that can be processed in solution. They have a nanoscale size and are driving the development of current and next-generation optoelectronic technologies due to their excellent performance and integrated morphology scalability. However, due to the quantum confinement effect, the limited number of atoms in quantum dots makes their energy level distribution discrete compared to bulk materials (producing similar molecular energy levels), and the quantization and discrete energy states of free carriers enable them to exhibit adjustable physical, electrical and optical properties. In turn, QDs can modulate the band gap width by adjusting their size. The smaller the size, the wider the band gap, and the more the absorption spectrum (Abs) and photoluminescence (PL) peak positions are blue-shifted toward the short-wave direction. This also provides a method for obtaining new semiconductor nanomaterials with excellent optoelectronic properties, that is, by rationally designing and regulating the size, morphology and other parameters of the semiconductor. In addition, the emergence of quantum dot materials provides a new idea for the design and preparation of high-performance semiconductor materials, that is, the material size effect can be used to regulate the physical, optical and electrical properties of the material. However, currently commercially available high-performance quantum dot materials usually contain highly toxic heavy metal elements such as cadmium or lead. The large-scale preparation and use of such materials poses a threat to human health and environmental safety. Therefore, it is urgent to develop low-toxicity, low-pollution, high-performance quantum dot materials.

[0003] Indium phosphide quantum dot materials have excellent optoelectronic properties and do not contain toxic heavy metal elements such as lead and cadmium. They are the most powerful alternative materials for the next generation of optoelectronic devices. Their fluorescence peak is adjustable in the visible to near-infrared emission range, with high fluorescence quantum yield and good stability. They have broad application prospects in new light-emitting devices, display devices, light detection devices and bioluminescent imaging. At present, breakthroughs have been made in red and green Indium phosphide quantum dot materials, with fluorescence quantum yields (PLQY) close to 100% and emission half-maximum width (FWHM) of nearly 30nm. However, the performance of blue light Indium phosphide quantum dot materials is currently poor, especially in the deep blue light field. The weak PLQY, wide FWHM and difficult-to-achieve short-wave emission wavelength seriously limit the development of Indium phosphide quantum dot materials in the field of high color purity full-color display.

[0004] The band gap of the InP bulk material is 1.35 eV. Compared with red and green InP QDs, in order to realize blue InP QDs, the core crystal should be smaller, and the band gap needs to be adjusted to 2.6-2.8 eV. The resulting problems, such as the reactivity of the precursor, the repeatability of the tiny particles, and defects and surface passivation, pose a huge challenge to the synthesis of InP QDs that emit light in the blue, especially deep blue regions. However, most of the current academic and industrial reports on blue light InP QDs are emitted in the sky blue light region (465-480 nm), and there are fewer reports on the synthesis route of blue InP QDs in the deep blue light region (450-465 nm). For example, the publication number CN113956879A provides a blue light indium phosphide quantum dot and its preparation method, electroluminescent device and display device, which discloses a blue light indium phosphide quantum dot. However, its PLQY is below 80%, and its optical performance is also poor.

[0005] Therefore, there is an urgent need for a deep blue light indium phosphide quantum dot material with excellent performance. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a deep blue emitting InP / ZnS blue light quantum dot and a preparation method thereof. The prepared deep blue light emitting indium phosphide blue light quantum dots have excellent optical properties, and the luminescent wavelength is tunable in the range of 438 to 468 nm. The preparation process is simple, the conditions are mild, and no heavy metals or toxic elements are contained.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a method for preparing deep blue emitting InP / ZnS blue light quantum dots, comprising the following steps:

[0009] At a first temperature, placing an indium precursor and a zinc precursor in a three-necked flask, then pre-evacuating the three-necked flask, and adding a coordination solvent into the flask to prepare an indium precursor mixed solution;

[0010] Based on the first temperature, raising the temperature to a second temperature, injecting a phosphorus source into the indium precursor mixed solution to obtain an indium phosphide mixed solution;

[0011] The sulfur precursor is injected into the indium phosphide mixed solution, and then the temperature is raised to a third temperature to react and generate indium phosphide quantum dots with a core-shell structure. After separation and purification, deep blue emitting InP / ZnS blue light quantum dots are obtained.

[0012] Preferably, the first temperature is 80-130°C, the second temperature is 140-240°C, and the third temperature is 280-320°C.

[0013] Preferably, the coordinating solvent is added to a three-necked flask to prepare an indium precursor mixed solution by pre-evacuating the three-necked flask, then adding the coordinating solvent into the flask, stirring and mixing evenly, and then evacuating the mixed solution in the flask under a nitrogen atmosphere to remove moisture and oxygen in the mixed solution, then stirring evenly to prepare the indium precursor mixed solution, and setting it aside at the first temperature.

[0014] Preferably, the indium precursor is one or more of indium chloride, indium bromide and indium iodide, the zinc precursor is one or more of zinc chloride, zinc bromide and zinc iodide, and the coordination solvent is oleylamine solution.

[0015] Preferably, the phosphorus source is tri(dimethylamino)phosphine, and the injection amount of the phosphorus source is not less than 4 mmol of phosphorus source per 1 mmol of indium precursor. The phosphorus source is injected into the indium precursor mixed solution for not less than 10 minutes to obtain an indium phosphide mixed solution.

[0016] Preferably, before injecting the sulfur precursor into the indium phosphide mixed solution, the method further comprises placing the sulfur precursor in a non-coordinating solvent and stirring the solvent evenly, and heating the solvent to a third temperature for standby use.

[0017] Preferably, the sulfur precursor is one or more of n-dodecyl mercaptan, n-octyl mercaptan, and n-hexyl mercaptan; and the non-coordinating solvent is one or more of tri-n-octylphosphine, dimethyl sulfoxide, octadecene, hexamethylphosphoramide, and pyridine.

[0018] The present invention also provides an InP / ZnS core-shell structure quantum dot that emits light in a deep blue region and is prepared by the above-mentioned preparation method. The indium phosphide blue light quantum dot adopts a core-shell structure formed on the basis of quantum dots, including an indium phosphide crystal core without added elements and an external zinc sulfide shell layer.

[0019] Preferably, the indium phosphide blue light quantum dots do not contain doping elements.

[0020] Preferably, the molar ratio of indium element to zinc element in the indium phosphide blue light quantum dots is 1:n, wherein 0<n≤12.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] (1) The present invention adopts quantum dots with a core-shell structure, which can effectively improve the optical performance and stability of indium phosphide blue light quantum dots; at the same time, zinc sulfide is used as the outer shell layer, which has strong chemical stability and a wide band gap, and can effectively improve the quantum confinement effect.

[0023] (2) The present invention uses a thiol precursor dissolved in a non-coordinating solvent and a zinc halide to grow a zinc sulfide shell, which effectively solves the problem that the fluorescence spectrum FWHM of the blue light indium phosphide quantum dots prepared by the prior art is relatively wide and the PL wavelength is only in the sky blue light or even cyan light range. The luminescent wavelength can cover the deep blue light range and can also obtain a narrower FWHM, effectively improving the optical properties of the indium phosphide quantum dots so that they can meet the high color purity and wide color gamut display applications.

[0024] (3) The present invention can effectively regulate the size of the core crystal and its size distribution by controlling the temperature and time window of nucleation, and can achieve tunable emission wavelength in the range of 438 to 458 nm while maintaining the FWHM between 39 nm and 59 nm. At the same time, the preparation process is relatively simple, and only mixing and a simple two-step heating reaction are used to prepare indium phosphide quantum dots that emit light in the deep blue light region, and the process conditions are mild and easy to control.

[0025] (4) The preparation method provided by the present invention does not contain heavy metals or toxic elements, is green and environmentally friendly, and has a highly repeatable process. It can stably prepare indium phosphide quantum dots that emit light in the deep blue region with both emission peak wavelength and half-peak width, and is easy to prepare in batches and also easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 This is a flow chart of a method for preparing deep blue emitting InP / ZnS blue light quantum dots of the present invention;

[0028] Figure 2 This is a summary diagram of the fluorescence emission spectrum performance of the deep blue region tunable InP QDs prepared by the present invention;

[0029] Figure 3 This is a fluorescence emission spectrum of deep blue InP QDs prepared in Example 1 of the present invention;

[0030] Figure 4 This is a fluorescence emission spectrum of deep blue InP QDs prepared in Example 2 of the present invention;

[0031] Figure 5 This is a fluorescence emission spectrum of deep blue InP QDs prepared in Example 3 of the present invention;

[0032] Figure 6This is a fluorescence emission spectrum of deep blue InP QDs prepared in Example 4 of the present invention;

[0033] Figure 7 This is a fluorescence emission spectrum of deep blue InP QDs prepared in Example 5 of the present invention;

[0034] Figure 8 This is the fluorescence emission spectrum of the deep blue light InP QDs prepared in Example 6 of the present invention;

[0035] Fig. 9 This is a transmission electron microscope image of the deep blue light InP QDs prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the present invention provides a method for preparing deep blue emitting InP / ZnS blue light quantum dots, comprising the following steps:

[0039] Step 100: placing an indium precursor and a zinc precursor in a three-necked flask at a first temperature, then pre-evacuating the three-necked flask, and adding a coordination solvent into the flask to prepare an indium precursor mixed solution;

[0040] Step 200: Based on the first temperature, the temperature is raised to a second temperature, and a phosphorus source is injected into the indium precursor mixed solution to obtain an indium phosphide mixed solution;

[0041] Step 300: injecting a sulfur precursor into the indium phosphide mixed solution, then heating it to a third temperature to react and generate indium phosphide quantum dots with a core-shell structure, and obtaining deep blue emitting InP / ZnS blue light quantum dots after separation and purification.

[0042] In the above steps, the first temperature is 80-130°C, the second temperature is 140-240°C, and the third temperature is 280-320°C.

[0043] In addition, in step 100, the coordination solvent is added to the three-necked flask to prepare the indium precursor mixed solution. The process is as follows: pre-evacuate the three-necked flask, then add the coordination solvent into the flask, stir and mix evenly, then evacuate the mixed solution in the flask under a nitrogen atmosphere to remove moisture and oxygen in the mixed solution, then stir evenly to prepare the indium precursor mixed solution, and store it at the first temperature for standby use. Wherein, the indium precursor is one or more of indium chloride, indium bromide and indium iodide, the zinc precursor is one or more of zinc chloride, zinc bromide and zinc iodide, and the coordination solvent is oleylamine solution.

[0044] In step 200, the phosphorus source is tri(dimethylamino)phosphine, and the injection amount of the phosphorus source is not less than 4 mmol of phosphorus source per 1 mmol of indium precursor. The phosphorus source is injected into the indium precursor mixed solution for not less than 10 minutes to obtain an indium phosphide mixed solution.

[0045] Before the sulfur precursor is injected into the indium phosphide mixed solution in step 300, the sulfur precursor is placed in a non-coordinating solvent and stirred evenly, and heated to a third temperature for standby use. The sulfur precursor is one or more of n-dodecyl mercaptan, n-octyl mercaptan, and n-hexyl mercaptan; the non-coordinating solvent is one or more of tri-n-octylphosphine, dimethyl sulfoxide, octadecene, hexamethylphosphoramide, and pyridine.

[0046] Through the above technical solution, the prepared deep blue emitting InP / ZnS blue light quantum dots adopt a core-shell structure formed on the basis of quantum dots, including an indium phosphide crystal core without doping elements and an external zinc sulfide shell layer. The indium phosphide blue light quantum dots do not contain doping elements. The molar ratio of indium element to zinc element in the indium phosphide blue light quantum dots is 1:n, where 0<n≤12. According to the above content, quantum dots with a core-shell structure are used to effectively improve the optical performance and stability of indium phosphide blue light quantum dots. At the same time, the present invention uses a zinc sulfide shell layer, which has strong chemical stability and a wide band gap, and can effectively confine core excitons. The present invention uses a thiol precursor dissolved in a non-coordinating solvent and a zinc halide to grow a zinc sulfide shell layer, which effectively solves the problem that the fluorescence spectrum FWHM of the blue light indium phosphide quantum dots prepared by the prior art is wide and the PL wavelength is only in the sky blue light or even cyan light range. The luminescent wavelength can cover the deep blue light range and can also obtain a narrower FWHM, effectively improving the optical performance of indium phosphide quantum dots, so that it can meet high color purity and wide color gamut display applications. The experimental conditions of the present invention are mild. By adjusting the nucleation temperature and duration and a special sulfur precursor for shell coating, an indium phosphide core crystal with a first exciton absorption peak between 380 and 420 nm can be obtained, and finally the luminescent wavelength can be tuned in the range of 438 to 468 nm.

[0047] According to the above content, the present invention lists the preparation process of Examples 1 to 6. In addition, the samples prepared in Examples 1 to 6 were tested to obtain the corresponding fluorescence emission spectra; Figure 2 The performance overview is shown in the figure. The emission wavelength of the prepared sample is adjustable between 438 and 468 nm. The optimal FWHM of the sample is less than 40 nm. The other samples are better than the existing similar quantum dots. Therefore, the specific implementation method is further described below.

[0048] Glossary: ​​QDs-quantum dots, InP QDs-indium phosphide quantum dots, (DMA)3P-tri(dimethylamino)phosphine, OT-n-octyl mercaptan, HT-n-hexyl mercaptan, DDT-n-dodecyl mercaptan, ZnI2-zinc iodide, OED-octadecene.

[0049] Example 1

[0050] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 468 nm and a half-peak width of 39 nm, which is prepared by the following steps:

[0051] S1. Preparation of In precursor mixed solution: add 0.4 mmol InCl3 and 2 mmol ZnI2 into a three-necked flask; store under vacuum at room temperature for 5 minutes; then add 6 ml OLA, heat the mixed solution to 100°C, and introduce N2 to remove water and oxygen for more than 60 minutes; then stir rapidly until the raw materials are completely dissolved to obtain a clear In precursor mixed solution, and keep the solution at 100°C for later use.

[0052] S2. Preparation of P precursor solution: Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0053] S3. Preparation of InP crystal nuclei: Heat the In precursor mixed solution of step S1 to 160°C, and quickly inject the P precursor solution prepared in step S2 at 160°C, and maintain this temperature for 2 hours to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nuclei products.

[0054] Preparation of S4, S precursor solution: Take 1 mL of one or more of HT, OT, DDT, and then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0055] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0056] S6. Preparation of core-shell structured InP QDs: slowly inject the S precursor solution prepared in step S4 into the solution containing the InP crystal core product in step S3, then quickly heat up to 280°C, and then quickly inject the Zn precursor solution prepared in step S5, and keep at this temperature for 60 minutes to form core-shell structured InP QDs with a zinc sulfide shell, and obtain a solution containing core-shell structured InP QDs products.

[0057] S7. Separation and purification of core-shell structure InP QDs: Take 100 μL of the solution containing the core-shell structure InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 10,000 r / pm for 3 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell structure InP QDs with an emission wavelength of 468 nm.

[0058] The fluorescence emission spectrum of the core-shell InP QDs prepared according to the above preparation process is as follows: Figure 3 As shown, the emission peak wavelength is located at 468nm, and the emission half-peak width is 39nm. Then, various tests were performed on the deep blue light core-shell structure InP QDs of Example 1, and the transmission electron microscope image thereof is shown in FIG. Fig. 9 It can be seen from the above test results that the performance of the deep blue light core-shell structure InPQDs of this embodiment is very excellent.

[0059] Example 2

[0060] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 465nm and a half-peak width of 39nm. The preparation process of this embodiment is as follows:

[0061] Preparation of S1, In precursor mixed solution:

[0062] Add 0.4 mmol of InCl3 and 2 mmol of ZnI2 to a three-necked flask; store under vacuum at room temperature for 5 minutes; then add 6 ml of OLA, heat the mixed solution to 100°C, and introduce N2 to remove water and oxygen for more than 60 minutes; then stir rapidly until the raw materials are completely dissolved to obtain a clear In precursor mixed solution, and keep the solution at 100°C for later use.

[0063] Preparation of S2 and P precursor solutions:

[0064] Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0065] S3. InP nucleus preparation:

[0066] The In precursor mixed solution of step S1 is heated to 150° C., and the P precursor solution prepared in step S2 is quickly injected at 150° C. The mixture is kept at this temperature for 2 hours to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nuclei products.

[0067] Preparation of S4, S precursor solution: take 2 mL of one or more of HT, OT, DDT, then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0068] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0069] S6. Preparation of core-shell InP QDs:

[0070] The S precursor solution prepared in step S4 is slowly injected into the solution containing the InP crystal nucleus product in step S3, and then the temperature is quickly raised to 280°C, and then the Zn precursor solution prepared in step S5 is quickly injected, and the temperature is maintained for 60 minutes to form a core-shell structured InP QDs with a zinc sulfide shell, and a solution containing a core-shell structured InP QDs product is obtained.

[0071] S7. Separation and purification of core-shell InP QDs:

[0072] Take 100 μL of the solution containing the core-shell InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 8000 r / pm for 5 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell InP QDs with an emission wavelength of 468 nm.

[0073] The core-shell InP QDs of this embodiment were detected. The emission wavelength of the InP QDs after separation and purification was located at 465 nm. The fluorescence emission spectrum is as follows: Figure 4 As shown, the emission peak wavelength is located at 465nm and the emission half-peak width is 39nm.

[0074] Example 3

[0075] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 458 nm and a half-peak width of 45 nm, which is prepared by the following steps:

[0076] S1. Preparation of In precursor mixed solution: add 0.4 mmol InCl3 and 2 mmol ZnI2 into a three-necked flask; store under vacuum at room temperature for 5 minutes; then add 6 ml OLA, heat the mixed solution to 100°C, and introduce N2 to remove water and oxygen for more than 60 minutes; then stir rapidly until the raw materials are completely dissolved to obtain a clear In precursor mixed solution, and keep the solution at 100°C for later use.

[0077] S2. Preparation of P precursor solution: Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0078] S3, InP crystal nucleus preparation: heat the In precursor mixed solution of step S1 to 140°C, and quickly inject the P precursor solution prepared in step S3 at 140°C, and keep this temperature for 2 hours to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nucleus products.

[0079] Preparation of S4, S precursor solution: take 4 mL of one or more of HT, OT, DDT, then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0080] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0081] S6. Preparation of core-shell structured InP QDs: slowly inject the S precursor solution prepared in step S4 into the solution containing the InP crystal core product in step S3, then quickly heat up to 280°C, and then quickly inject the Zn precursor solution prepared in step S5, and keep at this temperature for 60 minutes to form core-shell structured InP QDs with a zinc sulfide shell, and obtain a solution containing core-shell structured InP QDs products.

[0082] S7. Separation and purification of core-shell InP QDs:

[0083] Take 100 μL of the solution containing the core-shell InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 8000 r / pm for 5 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell InP QDs with an emission wavelength of 468 nm.

[0084] The fluorescence emission spectrum of the core-shell InP QDs of this embodiment is as follows: Figure 5 As shown, the emission peak wavelength is located at 458 nm and the emission half-peak width is 45 nm.

[0085] Example 4

[0086] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 455 nm and a half-peak width of 44 nm, which is prepared by the following steps:

[0087] S1. This step is the same as Example 1, except that the zinc-indium ratio is increased to 1:6, that is, 0.4 mmol of InCl3 and 2.4 mmol of ZnI2 are added to the three-necked flask.

[0088] S2. Preparation of P precursor solution: Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0089] S3. Preparation of InP crystal nuclei: Heat the In precursor mixed solution in step S1 to 130° C., and quickly inject the P precursor solution prepared in step S2 at 130° C., and maintain this temperature for 2 hours to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nuclei products.

[0090] Preparation of S4, S precursor solution: take 2 mL of one or more of HT, OT, DDT, then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0091] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0092] S6. Preparation of core-shell structured InP QDs: slowly inject the S precursor solution prepared in step S4 into the solution containing the InP crystal core product in step S3, then quickly heat up to 280°C, and then quickly inject the Zn precursor solution prepared in step S5, and keep at this temperature for 60 minutes to form core-shell structured InP QDs with a zinc sulfide shell, and obtain a solution containing core-shell structured InP QDs products.

[0093] S7. Separation and purification of core-shell structure InP QDs: Take 100 μL of the solution containing the core-shell structure InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 10,000 r / pm for 3 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell structure InP QDs with an emission wavelength of 468 nm.

[0094] The fluorescence emission spectrum of the core-shell InP QDs of this embodiment is as follows: Figure 6 As shown, the emission peak wavelength is located at 455 nm and the emission half-peak width is 44 nm.

[0095] Example 5

[0096] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 448 nm and a half-peak width of 46 nm, which is prepared by the following steps:

[0097] S1. This step is the same as Example 1, except that the zinc-indium ratio is increased to 1:7, that is, 0.4 mmol of InCl3 and 2.8 mmol of ZnI2 are added to the three-necked flask.

[0098] S2. Preparation of P precursor solution: Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0099] S3. Preparation of InP crystal nuclei: Heat the In precursor mixed solution in step S1 to 150° C., and quickly inject the P precursor solution prepared in step S2 at 150° C., and maintain this temperature for 1 hour to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nuclei products.

[0100] Preparation of S4, S precursor solution: take 4 mL of one or more of HT, OT, DDT, then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0101] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0102] S6. Preparation of core-shell structured InP QDs: slowly inject the S precursor solution prepared in step S4 into the solution containing the InP crystal core product in step S3, then quickly heat up to 280°C, and then quickly inject the Zn precursor solution prepared in step S5, and keep at this temperature for 60 minutes to form core-shell structured InP QDs with a zinc sulfide shell, and obtain a solution containing core-shell structured InP QDs products.

[0103] S7. Separation and purification of core-shell structure InP QDs: Take 100 μL of the solution containing the core-shell structure InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 10,000 r / pm for 3 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell structure InP QDs with an emission wavelength of 468 nm.

[0104] The fluorescence emission spectrum of the core-shell InP QDs of this embodiment is as follows: Figure 7As shown, the emission peak wavelength is located at 448 nm and the emission half-peak width is 46 nm.

[0105] Example 6

[0106] This embodiment provides a deep blue light indium phosphide quantum dot with an emission peak wavelength of 438 nm and a half-peak width of 59 nm, which is prepared by the following steps:

[0107] S1. This step is the same as Example 1, except that the zinc-indium ratio is increased to 1:12, that is, 0.4 mmol of InCl3 and 4.8 mmol of ZnI2 are added to the three-necked flask.

[0108] S2. Preparation of P precursor solution: Use 0.5 mL of (DMA)3P as a P source to prepare a P precursor solution for later use.

[0109] S3. Preparation of InP crystal nuclei: Heat the In precursor mixed solution in step S1 to 140°C, and quickly inject the P precursor solution prepared in step S2 at 10°C, and keep it at this temperature for 1 hour to form InP crystal nuclei, thereby obtaining a solution containing InP crystal nuclei products.

[0110] Preparation of S4, S precursor solution: take 4 mL of one or more of HT, OT, DDT, then add 2 mL of the aforementioned non-coordinating solvent respectively, heat and stir the mixed solution as the S precursor solution, and store it at the third temperature for later use.

[0111] S5. Preparation of Zn precursor solution: Add 2 mmol of ZnI2 and 5 ml of ODE into a three-necked flask, heat the mixed solution to 200°C under a nitrogen atmosphere, and cool the solution to room temperature after it becomes clear for later use.

[0112] S6. Preparation of core-shell structured InP QDs: slowly inject the S precursor solution prepared in step S4 into the solution containing the InP crystal core product in step S3, then quickly heat up to 280°C, and then quickly inject the Zn precursor solution prepared in step S5, and keep at this temperature for 60 minutes to form core-shell structured InP QDs with a zinc sulfide shell, and obtain a solution containing core-shell structured InP QDs products.

[0113] S7. Separation and purification of core-shell structure InP QDs: Take 100 μL of the solution containing the core-shell structure InP QDs product in step S6 and dissolve it in 2 mL of n-hexane, add 8 mL of ethanol, centrifuge at 10,000 r / pm for 3 min, take the precipitate and redisperse it in 5 mL of n-hexane to obtain purified core-shell structure InP QDs with an emission wavelength of 468 nm.

[0114] The fluorescence emission spectrum of the core-shell InP QDs of this embodiment is as follows: Figure 8 As shown, the emission peak wavelength is located at 438 nm and the emission half-peak width is 59 nm.

[0115] According to the above content, the samples prepared in Examples 1 to 6 were tested, and the fluorescence quantum yield and fluorescence emission peak were obtained based on the existing SCI paper public data (Comparative Example 1 is a narrow-band blue light-emitting indium phosphorus quantum dots induced by a high-activity zinc precursor proposed by ZHOU X et al.; Comparative Example 2 is a dual Zn and Ga modification strategy for high-efficiency deep blue InP / ZnSeS / ZnS quantum dots proposed by JIANG X et al.; Comparative Example 3 is the synthesis of colloidal blue-emitting InP / ZnS core-shell quantum dots assisted by copper ions proposed by HUANG F et al.). The specific test results are shown in Table 1.

[0116] Table 1 Test results

[0117]

[0118] It can be found from Table 1 that the core-shell structured indium phosphide quantum dots prepared by the present invention can achieve tuning in the deep blue light region while taking into account FWHM, and the fluorescence quantum yield can reach more than 80%. By precisely adjusting the nucleation temperature and time window and adjusting the amount of sulfur precursor added, the luminescent wavelength can be tuned in the range of 438 to 468 nm, and the optimal FWHM reaches 39 nm. All performances are significantly better than the blue light indium phosphide quantum dots in the prior art.

[0119] Therefore, by using the above-mentioned deep blue emitting InP / ZnS blue light quantum dots and the preparation method thereof, the prepared deep blue light emitting indium phosphide blue light quantum dots have excellent optical properties, and the emission wavelength is tunable in the range of 438 to 468 nm. The preparation process is simple, the conditions are mild, and no heavy metals or toxic elements are contained.

[0120] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0121] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing deep blue emitting InP / ZnS blue light quantum dots, characterized in that: The following steps are involved: At a first temperature, placing an indium precursor and a zinc precursor in a three-necked flask, then pre-evacuating the three-necked flask, and adding a coordination solvent into the flask to prepare an indium precursor mixed solution; Based on the first temperature, raising the temperature to a second temperature, injecting a phosphorus source into the indium precursor mixed solution to obtain an indium phosphide mixed solution; The sulfur precursor is injected into the indium phosphide mixed solution, and then the temperature is raised to a third temperature to react to generate indium phosphide quantum dots with a core-shell structure, and deep blue emitting InP / ZnS blue light quantum dots are obtained after separation and purification.

2. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 1, characterized in that: The first temperature is 80-130°C, the second temperature is 140-240°C, and the third temperature is 280-320°C.

3. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 1, characterized in that: The coordinating solvent is added to a three-necked flask to prepare an indium precursor mixed solution. The process is as follows: pre-evacuate the three-necked flask, then add the coordinating solvent into the flask, stir and mix evenly, then evacuate the mixed solution in the flask under a nitrogen atmosphere to remove moisture and oxygen in the mixed solution, then stir evenly to prepare the indium precursor mixed solution, and store it at the first temperature for use.

4. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 3, characterized in that: The indium precursor is one or more of indium chloride, indium bromide and indium iodide, the zinc precursor is one or more of zinc chloride, zinc bromide and zinc iodide, and the coordination solvent is oleylamine solution.

5. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 1, characterized in that: The phosphorus source is tri(dimethylamino)phosphine, and the injection amount of the phosphorus source is not less than 4 mmol of phosphorus source per 1 mmol of indium precursor. The phosphorus source is injected into the indium precursor mixed solution for not less than 10 minutes to obtain an indium phosphide mixed solution.

6. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 1, characterized in that: Before injecting the sulfur precursor into the indium phosphide mixed solution, the method further includes placing the sulfur precursor in a non-coordinating solvent, stirring the solvent evenly, and heating the solvent to a third temperature for standby use.

7. The method for preparing a deep blue emitting InP / ZnS blue light quantum dots according to claim 6, characterized in that: The sulfur precursor is one or more of n-dodecyl mercaptan, n-octyl mercaptan, and n-hexyl mercaptan; the non-coordinating solvent is one or more of tri-n-octylphosphine, dimethyl sulfoxide, octadecene, hexamethylphosphoramide, and pyridine.

8. The InP / ZnS core-shell structure quantum dots emitting deep blue light prepared by the method for preparing deep blue emitting InP / ZnS blue light quantum dots according to any one of claims 1 to 7, characterized in that: Indium phosphide blue light quantum dots adopt a core-shell structure formed on the basis of quantum dots, including an indium phosphide crystal core without added elements and an external zinc sulfide shell.

9. The InP / ZnS core-shell structure quantum dots emitting deep blue light prepared by the method for preparing deep blue emitting InP / ZnS blue light quantum dots according to claim 8, characterized in that: The indium phosphide blue light quantum dots do not contain doping elements.

10. The InP / ZnS core-shell structure quantum dots emitting deep blue light prepared by the method for preparing deep blue emitting InP / ZnS blue light quantum dots according to claim 9, characterized in that: The molar ratio of indium element to zinc element in the indium phosphide blue light quantum dots is 1:n, wherein 0<n≤12.

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