A core-shell structured indium phosphide quantum dot based on tripyrrolidinophosphine, and a preparation method and application thereof

Abstract

The present invention relates to the technical field of quantum dot luminescent materials, and discloses a core-shell structured indium phosphide quantum dot based on tripyrrolidinophosphine, a preparation method thereof, and an application thereof. Using tripyrrolidinophosphine as a brand-new phosphorus source, an indium phosphide inner core is first prepared, then a zinc selenide sulfide intermediate shell is coated, and finally a zinc precursor solution and a dodecanethiol solution are added to react to obtain a quantum dot solution, and the core-shell structured indium phosphide quantum dot is obtained through purification. The method of the present invention uses safe and environmentally friendly tripyrrolidinophosphine as a phosphorus source, and the reaction activity of this phosphorus source is lower than that of traditional phosphorus sources, which can better control the nucleation and growth of indium phosphide quantum dots, making the particle size distribution of the quantum dots more uniform, obtaining a core-shell structured indium phosphide quantum dot with a narrow full width at half maximum and a high quantum efficiency, and optimizing the luminescent performance of the core-shell structured indium phosphide quantum dots. The preparation method has a simple process, is safe and environmentally friendly, and can realize large-scale preparation.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot luminescent materials, and particularly to a core-shell structured indium phosphide quantum dot based on tri-pyrrolidinophosphine, and a preparation method and application thereof. Background Art

[0002] Quantum dots have wide applications in the fields of display, lighting, biology, etc. due to their unique optoelectronic properties. Currently, the types of quantum dots are mainly the following three categories: Cd-based quantum dots (CdSe, CdS, etc.), cadmium-free quantum dots (InP, CuInS2, etc.), and perovskite quantum dots (CsPbX3, X is a halogen such as Cl, Br, I). Among them, the development of Cd-based quantum dots and perovskite quantum dots is particularly prominent. However, since Cd-based quantum dots and perovskite quantum dots contain heavy metal elements such as Cd and Pb, which cause great harm to human health and environmental protection, their further development is restricted. Indium phosphide quantum dots have become a powerful alternative to Cd-based and Pb-based perovskite quantum dots due to their advantages such as adjustable emission bandgap in the entire visible light range and environmental friendliness.

[0003] In 1994, Micic et al. first used tris(trimethylsilyl)phosphine as a phosphorus source to react with indium chloride and oxalic acid dissolved in trioctylphosphine oxide for three days to successfully synthesize indium phosphide nanocrystals. However, due to the presence of a large number of defects on the surface of the indium phosphide nanocrystals, the luminescence performance of the indium phosphide nanocrystals was seriously affected [Nano Lett., 2002, 2(9): 1027-1030]. Among them, trioctylphosphine oxide is used as a coordinating solvent, and its boiling point is very high, resulting in the reaction being carried out at a very high temperature, making the reaction very slow and requiring a long time. To solve this problem, Peng Xiaogang et al. from Zhejiang University synthesized high-quality indium phosphide nanocrystals by using a non-coordinating solvent, 1-octadecene, instead of trioctylphosphine oxide in the presence of fatty acids, shortening the reaction time from several days to several hours and greatly saving the time cost. This synthesis method has provided great help for the subsequent synthesis of indium phosphide quantum dots [J. Nanopart. Res., 2013, 15(6): 1-10].

[0004] Compared with cadmium selenide quantum dots, the most prominent feature of indium phosphide quantum dots is their higher covalency, which results in higher carrier mobility and better stability. However, this also brings insurmountable difficulties. During the synthesis process, it is usually necessary to maintain the reaction at a relatively high temperature for a long time. Researchers have found that tris(trimethylsilyl)phosphine has high reactivity and the phosphorus precursor is consumed very quickly, resulting in insufficient supply of phosphorus monomers during nucleation and subsequent growth processes. Therefore, only Ostwald ripening process can be used to obtain the monomers required for the growth stage, but at the same time, the polydispersity increases, resulting in poor quality of the prepared indium phosphide quantum dots. At the same time, due to the high price, flammability, inconvenient transportation of tris(trimethylsilyl)phosphine, there are certain dangers and uncontrollability of the reaction. Therefore, it is urgent to find a suitable phosphorus source.

[0005] During the process of searching for a phosphorus source, researchers have tried to synthesize indium phosphide nanocrystals using phosphine gas generated by zinc phosphide, phosphorus trichloride, calcium phosphide, white phosphorus, etc., but no great achievements have been made. In 2013, the group of Heesun Yan first used inexpensive, safe and environmentally friendly tris(dimethylamino)phosphine as a phosphorus source to synthesize indium phosphide quantum dots, and obtained InP / ZnS core / shell quantum dots with a quantum efficiency of 51%-53% and a full width at half maximum of 60nm-64nm by coating a ZnS shell (J. Nanopart. Res., 2013, 15(6): 1-10).

[0006] In recent years, with the continuous optimization by researchers, the performance of indium phosphide quantum dots based on tris(dimethylamino)phosphine as a phosphorus source is almost comparable to that of tris(trimethylsilyl)phosphine (ACS Appl. Nano Mater., 2020). However, according to the Globally Harmonized System of Classification and Labelling of Chemicals, tris(dimethylamino)phosphine is still classified as a flammable liquid and vapor, which is harmful to human health and may cause genetic defects and cancer, hindering its practical application. The patent document number CN112143496A in 2021 disclosed a new type of phosphorus source M—(O—C≡P) n . Among them, M is a metal element. Using this phosphorus source, red light indium phosphide nanocrystals with a fluorescence peak value in the range of 580-670nm, a fluorescence emission peak width less than 50nm, and a quantum yield higher than 80% were synthesized, and good results were obtained using this phosphorus source. However, the synthesis conditions of this phosphorus source are relatively harsh, difficult to purchase, and difficult to prepare on a large scale. Summary of the Invention

[0007] Aiming at the problem that quantum dots prepared with tris(trimethylsilyl)phosphine or tris(dimethylamino)phosphine as a phosphorus source in the prior art are harmful to the human body, the present invention provides a core-shell structured indium phosphide quantum dot prepared with tripyrrolidinophosphine as a new phosphorus source, which is less harmful to the human body and the environment, greatly reduces potential safety hazards, and can be prepared on a large scale.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A preparation method of indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine, comprising the steps of:

[0010] Step 1, dissolving a zinc source, a selenium source and a sulfur source in a solvent respectively to form a zinc precursor solution, a selenium precursor solution and a sulfur precursor solution; dissolving tripyrrolidinophosphine in a solvent to form a phosphorus precursor solution;

[0011] Step 2, dissolving and mixing indium halide and zinc halide, heating to a first temperature for reaction, and then heating to a second temperature, and adding the phosphorus precursor solution for reaction to obtain an indium phosphide inner core solution;

[0012] Step 3, continuously adding the zinc precursor solution, the selenium precursor solution and the sulfur precursor solution to the indium phosphide inner core solution obtained in Step 2, and heating to a third temperature for reaction to obtain an indium phosphide solution coated with a zinc selenide sulfur intermediate shell;

[0013] Step 4, heating the solution in Step 3 to a fourth temperature, adding the zinc precursor solution and a dodecyl mercaptan solution for reaction to obtain a quantum dot solution, and purifying to obtain the indium phosphide quantum dots with the core-shell structure.

[0014] In the present invention, tripyrrolidinophosphine which is safe and environmentally friendly is used as the phosphorus source. By utilizing the characteristic that its reaction activity is relatively low, the nucleation and growth processes of indium phosphide quantum dots are more precisely controlled. The obtained core-shell structure quantum dots have a more uniform particle size distribution, a very narrow full width at half maximum (FWHM = 37 nm), and a high quantum efficiency (PLQY = 82.3%). This not only greatly reduces the safety hazards, but also optimizes the luminescence performance of the indium phosphide quantum dots with the core-shell structure.

[0015] The solvent used in the zinc precursor solution includes any one or more of octadecene, oleylamine, oleic acid, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene;

[0016] The solvents used in the selenium precursor solution and the sulfur precursor solution are independently selected from any one or more of trioctylphosphine, octadecene, oleylamine;

[0017] The solvent used in the phosphorus precursor solution includes any one or more of oleylamine, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine;

[0018] In Step 1, the precursor solution is prepared by heating and dissolving the raw materials in a solvent; heating can more effectively dissolve the raw materials fully. The heating temperature of the zinc precursor solution is 100 - 150 °C; the heating temperatures of the selenium precursor solution and the sulfur precursor solution are both 60 - 90 °C; the heating temperature of the phosphorus precursor solution is 30 - 70 °C.

[0019] The zinc source includes any one or more of zinc stearate, zinc acetate, zinc oxide, zinc chloride, zinc bromide, and zinc iodide;

[0020] The selenium source includes any one or more of selenium powder, selenium dichloride, selenium tetrachloride, phenylselenium chloride, selenol, and diselenide;

[0021] The sulfur source includes any one or more of sulfur powder, dodecanethiol, and octanethiol.

[0022] The concentration of the precursor solution should be such that the raw materials can be fully dissolved and dispersed evenly without precipitation; preferably, the molar ratio of the zinc source to the solvent is 1:5 - 10; the molar ratio of the selenium powder to the solvent is 0.5 - 2:1; the molar ratio of the sulfur powder to the solvent is 0.5:1 - 2:1; the molar ratio of tripyrrolidinophosphine to the solvent is 1:0.5 - 2.5.

[0023] The indium halide includes any one or more of indium iodide, indium bromide, and indium chloride;

[0024] The zinc halide includes any one or more of zinc bromide, zinc iodide, and zinc chloride;

[0025] In Step 2, the reaction solvent used includes any one or more of oleylamine, dodecane, hexadecane, hexadecylamine, octadecylamine, octylamine, oleic acid, and octadecene;

[0026] In Step 2, the molar ratio of indium halide, zinc halide, and tripyrrolidinophosphine is 1:(4.5 - 5.5):(3.4 - 5); tripyrrolidinophosphine refers to the content of tripyrrolidinophosphine in the phosphorus precursor solution. This ratio can make the crystallization quality and seed morphology of the synthesized indium phosphide core more excellent, and the particle size of the indium phosphide quantum dots more uniform.

[0027] In Step 2, the first temperature is 120 - 140°C and the second temperature is 190 - 200°C. When the temperature is maintained at the first temperature of 120°C - 140°C, excess residual water vapor and oxygen will be generated in the reaction system. To avoid affecting the surface of indium phosphide quantum dots, harmful gases generated in the reaction system are removed by vacuum pumping when heated to 120 - 140°C. When the temperature is at the second temperature of 190 - 200°C, the addition of the phosphorus precursor is related to the reaction activity. The slow reaction activity is reflected in the adjustment of the reaction time. Compared with the relatively fast reaction time of tris(dimethylamino)phosphine (6 - 10 min), the reaction time of tripyrrolidinophosphine is longer than that of tris(dimethylamino)phosphine, being 10 - 20 min. The longer reaction time is used for the uniform and slow nucleation of indium phosphide quantum dots, reducing surface defects, suppressing the non-radiative recombination probability of lattice internal stress and excitons, and being beneficial to improving the quantum yield.

[0028] In Step 2, the reaction time at the first temperature is 30 - 60 min; after adding the phosphorus precursor solution, the reaction is carried out for 10 - 20 min; reacting for 30 - 60 min at the first temperature can remove the excess water vapor and oxygen generated during the reaction process; reacting for 10 - 20 min after adding the phosphorus precursor solution can enable the stable nucleation of indium phosphide quantum dots, ensuring the uniformity of the size distribution.

[0029] In Step 3, the molar ratio of the zinc source in the zinc precursor solution, the selenium source in the selenium precursor solution, the sulfur source in the sulfur precursor solution to indium halide is (9 - 12.5):(2.5 - 5.5):(2.5 - 5.5):1;

[0030] In Step 3, the third temperature is 260 - 280°C and the reaction time is 90 - 120 min; the growth of the ZnSeS shell passivates the defects on the surface of the indium phosphide core, alleviates the lattice mismatch between the indium phosphide core and the outer shell ZnS, and reduces the interface defects.

[0031] In Step 4, the molar ratio of the zinc source in the zinc precursor solution, dodecanethiol to indium halide is (2.5 - 5.5):(9 - 19):1; the quantum dots obtained using this component ratio have a higher quantum yield.

[0032] In Step 4, the fourth temperature is 290 - 300°C and the reaction is carried out for 60 - 80 min. ZnS is a wide-bandgap semiconductor material. The encapsulation of the ZnS outer shell further inhibits the escape of excitons to the outer shell, avoids the direct contact between external water, oxygen and indium phosphide quantum dots, and improves the luminescence performance of the quantum dots.

[0033] The whole process of the preparation method of the core-shell structure indium phosphide quantum dots in the present invention is carried out under the protection of an inert gas atmosphere, and the inert gas is at least one of nitrogen and argon.

[0034] The nucleation time of the phosphorus source used in the present invention (10 - 20 min) is longer than that of the traditional tris(dimethylamino)phosphine (6 - 10 min), indicating that the reactivity of this phosphorus source is relatively low. There is sufficient monomer supply during the nucleation and growth of quantum dots, and it does not enter the Ostwald ripening stage prematurely. Therefore, the particle size distribution is uniform, which is manifested as a narrower full width at half maximum in the spectrum, and the obtained quantum dots have more excellent performance.

[0035] Preferably, in step 3, the selenium precursor solution and the sulfur precursor solution are respectively added to the reaction solution at a rate of 0.5 - 2 mL / h. During the growth of the ZnSeS shell, in order to obtain a uniform and densely grown ZnSeS shell, we drop the selenium and sulfur precursor solutions into the reaction solution at a constant speed.

[0036] Preferably, in step 4, 1 - dodecanethiol is added to the reaction solution at a rate of 1 - 3 mL / h. During the growth of the ZnS shell, in order to obtain a uniform and densely grown ZnS shell, we drop 1 - dodecanethiol into the reaction solution at a constant speed.

[0037] Preferably, the purification in step 4 includes the steps of: dissolving the reaction solution in a non - polar solvent, centrifuging, then adding it to a polar solvent to precipitate, and filtering to obtain the core - shell structured indium phosphide quantum dots.

[0038] The non - polar solvent includes any one or more of n - octane, n - hexane, and toluene;

[0039] The polar solvent includes any one or more of ethanol, acetone, and methanol.

[0040] The volume ratio of the non - polar solvent to the polar solvent is 1 - 2:1 - 3.

[0041] The present invention also provides a core - shell structured indium phosphide quantum dot prepared by the described preparation method. This quantum dot has safe raw materials, less harm to humans and the environment, excellent luminescence properties, a narrow full width at half maximum, and a high quantum efficiency, and the quantum efficiency is above 50%.

[0042] Based on the excellent environmental protection and luminescence properties of the quantum dots of the present invention, the present invention also provides the application of the described core - shell structured indium phosphide quantum dots in the optoelectronic field, which has great potential to replace indium phosphide quantum dots prepared by existing phosphorus sources.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The method of the present invention uses safe and environmentally friendly tripyrrolidinophosphine as the phosphorus source. This phosphorus source has lower reactivity compared to traditional phosphorus sources, enabling better control of the nucleation and growth of indium phosphide quantum dots, resulting in a more uniform particle size distribution of the quantum dots. Moreover, this preparation method has a simple process, is easy to purchase, causes less harm to the human body and the environment, greatly reduces safety hazards, and can achieve large-scale preparation.

[0045] (2) By regulating the amount of zinc source added during the growth of ZnS, the method of the present invention restricts the epitaxy of excitons to the shell layer, enhances radiative recombination, and obtains core-shell structured indium phosphide quantum dots with a narrow full width at half maximum (the lowest FWHM = 37 nm) and a high quantum efficiency (the highest PLQY = 82.3%), optimizing the luminescence performance of the core-shell structured indium phosphide quantum dots. Description of the Drawings

[0046] Figure 1 is the preparation flow chart of the core-shell structured indium phosphide quantum dots provided by the present invention.

[0047] Figure 2 is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 1.

[0048] Figure 3 is the fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 1.

[0049] Figure 4 is the lifetime decay curve picture of the core-shell structured indium phosphide quantum dots prepared in Example 1.

[0050] Figure 5 is the TEM picture of the core-shell structured indium phosphide quantum dots prepared in Example 1.

[0051] Figure 6 is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 2.

[0052] Figure 7 is the fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 2.

[0053] Figure 8 is the lifetime decay curve picture of the core-shell structured indium phosphide quantum dots prepared in Example 2.

[0054] Figure 9 is the TEM picture of the core-shell structured indium phosphide quantum dots prepared in Example 2.

[0055] Figure 10 is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 3.

[0056] Figure 11The fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Example 3.

[0057] Figure 12 The lifetime decay curve picture of the core-shell structured indium phosphide quantum dots prepared in Example 3.

[0058] Figure 13 The TEM picture of the core-shell structured indium phosphide quantum dots prepared in Example 3.

[0059] Figure 14 The ultraviolet absorption spectrum picture of the core indium phosphide quantum dots prepared in Comparative Example 1.

[0060] Figure 15 The fluorescence emission spectrum picture of the core indium phosphide quantum dots prepared in Comparative Example 1.

[0061] Figure 16 The lifetime decay curve picture of the core indium phosphide quantum dots prepared in Comparative Example 1.

[0062] Figure 17 The TEM picture of the core indium phosphide quantum dots prepared in Comparative Example 1.

[0063] Figure 18 The ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Comparative Example 2.

[0064] Figure 19 The fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in Comparative Example 2.

[0065] Figure 20 The lifetime decay curve picture of the core-shell structured indium phosphide quantum dots prepared in Comparative Example 2.

[0066] Figure 21 The TEM picture of the core-shell structured indium phosphide quantum dots prepared in Comparative Example 2.

[0067] Figure 22 The XRD picture of the core-shell structured indium phosphide quantum dots of the examples and comparative examples. Detailed implementation manners

[0068] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Those skilled in the art who make modifications or equivalent replacements on the basis of understanding the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall all be covered within the protection scope of the present invention.

[0069] The preparation process of the core-shell structured indium phosphide quantum dots based on tripyrrolidinophosphine of the present invention is as Figure 1 shown, specifically:

[0070] Step 1, Preparation of zinc, selenium, sulfur, and phosphorus precursor solutions:

[0071] Preparation of zinc precursor solution: A zinc source and a non-coordinating solvent with a molar ratio of 1:5 to 10 are mixed and dissolved in a three-necked flask, and heated and stirred at 100 to 150 °C and a rotation speed of 300 to 1000 revolutions per minute under a nitrogen atmosphere until the solution becomes clear and transparent, obtaining the zinc precursor solution;

[0072] Preparation of selenium precursor solution: Under a nitrogen atmosphere, selenium powder and trioctylphosphine are mixed in a sample bottle, and heated and stirred at 60 to 90 °C and a rotation speed of 300 to 1000 revolutions per minute for 10 to 60 minutes, obtaining the selenium precursor solution;

[0073] Preparation of sulfur precursor solution: Under a nitrogen atmosphere, sulfur powder and trioctylphosphine are mixed in a sample bottle, and heated and stirred at 60 to 90 °C and a rotation speed of 300 to 1000 revolutions per minute for 10 to 60 minutes, obtaining the sulfur precursor solution;

[0074] Preparation of phosphorus precursor solution: Using tripyrrolidinophosphine as a novel phosphorus source, under a nitrogen atmosphere, tripyrrolidinophosphine and an organic amine with a molar ratio of 1:0.5 to 2.5 are mixed in a sample bottle and heated and stirred at 30 to 70 °C and a rotation speed of 300 to 1000 revolutions per minute for 10 to 60 minutes, obtaining the phosphorus precursor solution;

[0075] Step 2, Preparation of indium phosphide core solution:

[0076] Indium halide, zinc halide, and an organic solvent are mixed and dissolved in a three-necked flask, and stirred and heated under a nitrogen atmosphere and a rotation speed of 300 to 1000 revolutions per minute. When the temperature rises to the range of 120 to 140 °C, vacuum is pumped for 30 to 90 minutes, then nitrogen is backfilled. Under a nitrogen atmosphere, the temperature is further raised to the range of 190 to 200 °C, and the phosphorus precursor solution is injected and maintained for 10 to 20 minutes to complete the preparation of the indium phosphide core solution. Among them, the molar ratio of indium halide, zinc halide, organic solvent, and the phosphorus source in the phosphorus precursor is 1:4.1 to 4.8:30.6 to 47.6:3.4 to 5;

[0077] Step 3, Coating of zinc-selenium-sulfur intermediate shell:

[0078] Inject the zinc precursor solution into the indium phosphide core solution within the range of 190 - 200 °C. Meanwhile, inject the selenium precursor solution and the sulfur precursor solution at a rate of 0.5 mL / hour - 2 mL / hour, and raise the temperature to within the range of 260 - 280 °C, and maintain for 90 - 120 minutes to complete the coating of the zinc selenium sulfur intermediate shell layer. Among them, the molar ratio of zinc source in the zinc precursor, selenium powder in the selenium precursor, sulfur powder in the sulfur precursor to indium halide is 9 - 12.5:2.5 - 5.5:2.5 - 5.5:1;

[0079] Step 4, coating of the zinc sulfide outer shell layer:

[0080] After completing the coating of the zinc selenium sulfur intermediate shell layer, continue to raise the temperature until it stabilizes within the range of 290 - 300 °C, inject the zinc precursor solution, and inject the dodecanethiol solution at a rate of 1 mL / hour - 3 mL / hour, and maintain for 60 - 80 minutes to complete the coating of the zinc sulfide outer shell layer. Among them, the molar ratio of zinc source in the zinc precursor, dodecanethiol to indium halide is 2.6 - 5.4:9.4 - 19:1;

[0081] Step 5, purify to obtain the product:

[0082] After completing the coating of the zinc sulfide outer shell layer, naturally cool the temperature to room temperature, then add the non-polar solvent n-octane to dissolve, centrifuge at a rotation speed of 5000 - 12000 revolutions for 3 - 8 minutes, and then add the polar solvent ethanol to precipitate. Among them, the volume ratio of the non-polar solvent to the polar solvent is 1 - 2:1 - 3 to complete the preparation of the core-shell structured indium phosphide quantum dots.

[0083] The raw materials used in the following specific embodiments are all purchased from commercial reagent companies.

[0084] Example 1

[0085] Preparation of core-shell structured indium phosphide quantum dots based on tripyrrolidinophosphine as the phosphorus source:

[0086] Step 1, preparation of zinc, selenium, sulfur, and phosphorus precursor solutions:

[0087] Preparation of the zinc precursor solution: Mix 6 grams of zinc stearate (9.48 mmol) and 24 mL of octadecene in a three-necked flask, heat at 150 °C under a nitrogen atmosphere and a rotation speed of 900 revolutions until the solution becomes clear and transparent to obtain the zinc precursor solution.

[0088] Preparation of the selenium precursor solution: Under a nitrogen atmosphere, mix 2.4 mmol of selenium powder and 1 mL of trioctylphosphine in a sample bottle, heat and stir at 80 °C and 600 revolutions for 30 minutes to obtain the selenium precursor.

[0089] Preparation of sulfur precursor: Under a nitrogen atmosphere, 2.4 millimoles of sulfur powder and 1 milliliter of trioctylphosphine were mixed in a sample bottle and heated with stirring at 80 °C and 600 rpm for 30 minutes to obtain the sulfur precursor.

[0090] Preparation of phosphorus precursor solution: Under a nitrogen atmosphere, 1.96 millimoles of tripyrrolidinophosphine and 3 millimoles (1 mL, 2.99 mmol) of oleylamine were mixed in a sample bottle and heated with stirring at 50 °C and 600 rpm for 30 minutes to obtain 1.45 milliliters of the phosphorus precursor.

[0091] Step 2, Preparation of indium phosphide core solution:

[0092] 0.44 millimoles of indium iodide, 2.2 millimoles of zinc bromide, and 5 milliliters of oleylamine were mixed in a three-necked flask, stirred and heated under a nitrogen atmosphere at a rotation speed of 700 rpm. When the temperature rose to 130 °C, it was evacuated for 60 minutes, then backfilled with nitrogen. Under a nitrogen atmosphere, the temperature was continued to be raised to 200 °C, and 1.45 milliliters (1 mL oleylamine + 0.45 mL phosphorus source) of the phosphorus precursor solution was injected and held for 20 minutes to complete the preparation of the indium phosphide core solution.

[0093] Step 3, Coating of zinc selenide sulfur intermediate shell:

[0094] At a temperature of 200 °C, (12 milliliters) 4.74 mmol of the zinc source zinc precursor solution was injected into the indium phosphide core solution obtained in Step 2. At the same time, 1 milliliter of selenium and sulfur precursor solutions were sequentially injected at a rate of 1 milliliter per hour, and the temperature was raised to 270 °C and held for 120 minutes to complete the coating of the zinc selenide sulfur intermediate shell.

[0095] Step 4, Coating of zinc sulfide outer shell:

[0096] On the basis of Step 3, the temperature was continuously raised until it stabilized at 290 °C, 3 milliliters of the zinc precursor solution (0.75 g, 1.18 mmol zinc source) was injected, and 1.5 milliliters (6.26 mmol) of 1-dodecanethiol solution was injected at a rate of 3 milliliters per hour and held for 70 minutes to complete the coating of the zinc sulfide outer shell.

[0097] Step 5, Cooling and purification to obtain core-shell structured indium phosphide quantum dots:

[0098] On the basis of Step 4, the temperature is naturally cooled to room temperature. The solution cooled to room temperature is added with 10 mL of n-hexane, and then centrifuged at 10,000 rpm for 4 minutes to remove impurities. The obtained supernatant is mixed with ethanol in a 1:1 ratio and centrifuged at 10,000 rpm for 4 minutes. The obtained precipitate is dissolved in 2 mL of n-hexane, and then 2 mL of ethanol is added for precipitation. After centrifugation at 10,000 rpm for 3 minutes, the supernatant is discarded and the precipitate is retained, completing the preparation of the core-shell structured indium phosphide quantum dots.

[0099] Figure 2 It is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this example. Figure 3 It is the fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the fluorescence emission peak position of the core-shell structured indium phosphide quantum dots prepared in this example is at 510 nm, the full width at half maximum is 52 nm, and the quantum efficiency is about 58%.

[0100] Figure 4 It is the fluorescence lifetime decay curve graph of the quantum dots prepared in this example. By double-exponentially fitting the decay lifetime, it can be known that the average fluorescence lifetime of the quantum dots is about 76 ns. The fluorescence lifetime is short and the radiation rate is fast, which is consistent with the relatively high fluorescence quantum yield of this quantum dot. Figure 5 It is the TEM picture of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the particle size distribution of this quantum dot is relatively uniform, and its average particle size is about 8.6 nm. The advantage of the uniform particle size of the quantum dots is also consistent with the relatively narrow emission spectrum.

[0101] Example 2

[0102] Preparation of core-shell structured indium phosphide quantum dots based on tri-pyrrolidinophosphine as the phosphorus source:

[0103] Step 1, preparation of zinc, selenium, sulfur, and phosphorus precursor solutions:

[0104] Preparation of zinc precursor solution: 6 g of zinc stearate (9.48 mmol) and 24 mL of octadecene are mixed in a three-necked flask and heated at 150 °C under a nitrogen atmosphere and a rotation speed of 900 rpm until the solution becomes clear and transparent, obtaining the zinc precursor solution.

[0105] Preparation of selenium precursor solution: Under a nitrogen atmosphere, 2.4 mmol of selenium powder and 1 mL of trioctylphosphine are mixed in a sample bottle and heated and stirred at 80 °C and 600 rpm for 30 minutes to obtain the selenium precursor.

[0106] Preparation of sulfur precursor: Under a nitrogen atmosphere, 2.4 mmol of sulfur powder and 1 mL of trioctylphosphine are mixed in a sample bottle and heated and stirred at 80 °C and 600 rpm for 30 minutes to obtain the sulfur precursor.

[0107] Preparation of phosphorus precursor solution: Under a nitrogen atmosphere, 1.96 mmol of tripyrrolidinophosphine and 3 mmol of oleylamine were mixed in a sample bottle and heated with stirring at 55 °C and 600 rpm for 30 minutes to obtain 1.45 mL of the phosphorus precursor.

[0108] Step 2, preparation of indium phosphide core solution:

[0109] 0.44 mmol of indium iodide, 2.2 mmol of zinc bromide, and 5 mL of oleylamine were mixed in a three-necked flask, stirred and heated under a nitrogen atmosphere at a rotation speed of 700 rpm. When the temperature rose to 130 °C, vacuum was pumped for 60 minutes, then nitrogen was backfilled. Under a nitrogen atmosphere, the temperature was continuously raised to 200 °C, 1.45 mL of the phosphorus precursor solution was injected, and it was maintained for 20 minutes to complete the preparation of the indium phosphide core solution.

[0110] Step 3, coating of zinc selenium sulfur intermediate shell:

[0111] At 200 °C, 12 mL of the zinc precursor solution was injected into the indium phosphide core solution obtained in Step 2. At the same time, 1 mL of selenium and sulfur precursor solutions were successively injected at a rate of 1 mL / h, and the temperature was raised to 270 °C and maintained for 120 minutes to complete the coating of the zinc selenium sulfur intermediate shell.

[0112] Step 4, coating of zinc sulfide outer shell:

[0113] On the basis of Step 3, the temperature was continuously raised until it stabilized at 290 °C, 5 mL of the zinc precursor solution (1.25 g zinc source, 1.97 mmol) was injected, and 1.5 mL of 1-dodecanethiol solution was injected at a rate of 3 mL / h and maintained for 70 minutes to complete the coating of the zinc sulfide outer shell.

[0114] Step 5, cooling and purification to obtain core-shell structured indium phosphide quantum dots:

[0115] On the basis of Step 4, the temperature was naturally cooled to room temperature. The solution cooled to room temperature was added with 10 mL of n-hexane, and then centrifuged at 10,000 rpm for 4 minutes to remove impurities. The obtained supernatant was mixed with ethanol at a ratio of 1:1 and centrifuged at 10,000 rpm for 4 minutes. The obtained precipitate was dissolved in 2 mL of n-hexane, then 2 mL of ethanol was added for precipitation, and centrifuged at 10,000 rpm for 3 minutes. The supernatant was discarded and the precipitate was retained to complete the preparation of the core-shell structured indium phosphide quantum dots.

[0116] Figure 6 It is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this example. Figure 7It is a picture of the fluorescence emission spectrum of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the fluorescence emission peak position of the core-shell structured indium phosphide quantum dots prepared in this example is at 525 nm, the full width at half maximum is 37 nm, and the quantum efficiency is 82.3%. Figure 8 It is the lifetime decay curve graph of this example. Figure 9 It is the TEM image of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the particle size distribution of the quantum dots is uniform, and its average particle size is about 5.5 nm.

[0117] Example 3

[0118] Preparation of core-shell structured indium phosphide quantum dots based on tripyrrolidinophosphine as the phosphorus source:

[0119] Step 1, preparation of zinc, selenium, sulfur, and phosphorus precursor solutions:

[0120] Preparation of zinc precursor solution: Mix 6 grams of zinc stearate (9.48 mmol) and 24 ml of octadecene in a three-necked flask, heat at 150 °C under a nitrogen atmosphere with a rotation speed of 900 rpm until the solution becomes clear and transparent to obtain the zinc precursor solution.

[0121] Preparation of selenium precursor solution: Under a nitrogen atmosphere, mix 2.4 mmol of selenium powder and 1 ml of trioctylphosphine in a sample bottle, heat and stir at 80 °C and 600 rpm for 30 minutes to obtain the selenium precursor.

[0122] Preparation of sulfur precursor: Under a nitrogen atmosphere, mix 2.4 mmol of sulfur powder and 1 ml of trioctylphosphine in a sample bottle, heat and stir at 80 °C and 600 rpm for 30 minutes to obtain the sulfur precursor.

[0123] Preparation of phosphorus precursor solution: Under a nitrogen atmosphere, mix 1.96 mmol of tripyrrolidinophosphine and 3 mmol of oleylamine in a sample bottle, heat and stir at 55 °C and 600 rpm for 30 minutes to obtain 1.45 ml of the phosphorus precursor.

[0124] Step 2, preparation of indium phosphide core solution:

[0125] Mix 0.44 mmol of indium iodide, 2.2 mmol of zinc bromide, and 5 ml of oleylamine in a three-necked flask, stir and heat under a nitrogen atmosphere with a rotation speed of 700 rpm. When the temperature rises to 130 °C, evacuate for 60 minutes, then backfill with nitrogen. Under a nitrogen atmosphere, continue to raise the temperature to 200 °C, inject 1.45 ml of the phosphorus precursor solution, and hold for 20 minutes to complete the preparation of the indium phosphide core solution.

[0126] Step 3, coating of the zinc-selenium-sulfur intermediate shell:

[0127] At a temperature of 200 °C, 12 mL of the zinc precursor solution was injected into the indium phosphide core solution obtained in Step 2. At the same time, 1 mL of the selenium and sulfur precursor solutions were sequentially injected at a rate of 1 mL / hour, and the temperature was raised to 270 °C and maintained for 120 minutes to complete the coating of the zinc selenium sulfur intermediate shell.

[0128] Step 4, Coating of the zinc sulfide outer shell:

[0129] Based on Step 3, the temperature was continuously raised until it stabilized at 290 °C. 6 mL (1.5 g, 2.37 mmol zinc source) of the zinc precursor solution was injected, and 1.5 mL of 1-dodecanethiol solution was injected at a rate of 3 mL / hour and maintained for 70 minutes to complete the coating of the zinc sulfide outer shell.

[0130] Step 5, Cooling and purification to obtain core-shell structured indium phosphide quantum dots:

[0131] Based on Step 4, the temperature was naturally cooled to room temperature. The solution cooled to room temperature was added with 10 mL of n-hexane, and then centrifuged at 10,000 revolutions per minute for 4 minutes to remove impurities. The obtained supernatant was mixed with ethanol at a ratio of 1:1 and centrifuged at 10,000 revolutions per minute for 4 minutes. The resulting precipitate was dissolved in 2 mL of n-hexane, and then 2 mL of ethanol was added for precipitation and centrifuged at 10,000 revolutions per minute for 3 minutes. The supernatant was discarded and the precipitate was retained to complete the preparation of the core-shell structured indium phosphide quantum dots.

[0132] Figure 10 is the ultraviolet absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this example. Figure 11 is the fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the fluorescence emission peak position of the core-shell structured indium phosphide quantum dots prepared in this example is at 541 nm, the full width at half maximum is 48 nm, and the quantum efficiency is about 51.6%. Figure 12 is the lifetime decay curve graph of this example. Figure 13 is the TEM picture of the core-shell structured indium phosphide quantum dots prepared in this example. It can be seen that the quantum dots are relatively uniformly distributed and their average particle size is about 7.2 nm.

[0133] Comparative Example 1

[0134] Preparation of core indium phosphide quantum dots based on tripyrrolidinophosphine as the phosphorus source

[0135] Step 1, Preparation of the phosphorus precursor solution:

[0136] Under a nitrogen atmosphere, 1.96 mmol of tripyrrolidinophosphine and 3 mmol of oleylamine were mixed in a sample bottle and heated and stirred at 55 °C and 600 revolutions per minute for 30 minutes to obtain 1.45 mL of the phosphorus precursor.

[0137] Step 2, Preparation of indium phosphide core solution:

[0138] Mix 0.44 mmol of indium iodide, 2.2 mmol of zinc bromide, and 5 mL of oleylamine in a three-necked flask, stir and heat under a nitrogen atmosphere at a rotation speed of 700 rpm. When the temperature rises to 130 °C, evacuate for 60 minutes, then backfill with nitrogen. Under a nitrogen atmosphere, continue to raise the temperature to 200 °C, inject 1.45 mL of phosphorus precursor solution, and hold for 20 minutes to complete the preparation of the indium phosphide core solution.

[0139] Step 3, Cooling and purification to obtain core indium phosphide quantum dots:

[0140] Based on Step 2, naturally cool the temperature to room temperature, add 5 mL of n-hexane to the solution cooled to room temperature, then centrifuge at a rotation speed of 10000 rpm for 4 minutes to remove impurities. Mix the obtained supernatant with ethanol at a ratio of 1:1 and centrifuge at a rotation speed of 10000 rpm for 4 minutes. Dissolve the obtained precipitate in 2 mL of n-hexane, then continue to add 2 mL of ethanol for precipitation, and centrifuge at a rotation speed of 10000 rpm for 3 minutes. Discard the supernatant and retain the precipitate to complete the preparation of the core indium phosphide quantum dots.

[0141] Figure 14 This is the UV absorption spectrum picture of the core indium phosphide quantum dots prepared in this comparative example. Figure 15 This is the fluorescence emission spectrum picture of the core indium phosphide quantum dots prepared in this comparative example. It can be seen that the fluorescence emission peak position of the quantum dots is at 512 nm, the full width at half maximum is 55 nm, and the quantum efficiency is about 6.2%. Compared with the quantum dots with a core-shell structure, its quantum efficiency is poor. Figure 16 This is the lifetime decay curve graph of the quantum dots. Figure 17 This is the TEM picture of the core indium phosphide quantum dots prepared in this comparative example. It can be seen that the quantum dots are relatively uniformly distributed and their average particle size is about 5.2 nm.

[0142] Comparative Example 2

[0143] Preparation of core-shell indium phosphide quantum dots based on tris(dimethylamino)phosphine as the phosphorus source

[0144] Step 1, Preparation of zinc, selenium, sulfur, and phosphorus precursor solutions:

[0145] Preparation of zinc precursor solution: Mix 6 g of zinc stearate (9.48 mmol) and 24 mL of octadecene in a three-necked flask, heat at 150 °C under a nitrogen atmosphere at a rotation speed of 900 rpm until the solution becomes clear and transparent to obtain the zinc precursor solution.

[0146] Preparation of selenium precursor solution: Under a nitrogen atmosphere, 2.4 millimoles of selenium powder and 1 milliliter of trioctylphosphine were mixed in a sample bottle and heated with stirring at 80 °C and 600 rpm for 30 minutes to obtain the selenium precursor.

[0147] Preparation of sulfur precursor: Under a nitrogen atmosphere, 2.4 millimoles of sulfur powder and 1 milliliter of trioctylphosphine were mixed in a sample bottle and heated with stirring at 80 °C and 600 rpm for 30 minutes to obtain the sulfur precursor.

[0148] Preparation of phosphorus precursor solution: Under a nitrogen atmosphere, 2.48 millimoles of tris(dimethylamino)phosphine and 3 millimoles of oleylamine were mixed in a sample bottle and heated with stirring at 50 °C and 600 rpm for 30 minutes to obtain 1.45 milliliters of the phosphorus precursor.

[0149] Step 2, preparation of indium phosphide core solution:

[0150] 0.44 millimoles of indium iodide, 2.2 millimoles of zinc bromide, and 5 milliliters of oleylamine were mixed in a three-necked flask, stirred and heated under a nitrogen atmosphere at a rotation speed of 700 rpm. When the temperature rose to 130 °C, vacuum was pumped for 60 minutes, then nitrogen was backfilled. Under a nitrogen atmosphere, the temperature was continuously raised to 200 °C, 1.45 milliliters of the phosphorus precursor solution was injected, and it was maintained for 6 - 10 minutes to complete the preparation of the indium phosphide core solution. Step 3, coating of the zinc selenium sulfur intermediate shell:

[0151] At a temperature of 200 °C, 12 milliliters of the zinc precursor solution was injected into the indium phosphide core solution obtained in Step 2. Meanwhile, 1 milliliter of the selenium and sulfur precursor solutions were sequentially injected at a rate of 1 milliliter per hour, and the temperature was raised to 270 °C and maintained for 120 minutes to complete the coating of the zinc selenium sulfur intermediate shell.

[0152] Step 4, coating of the zinc sulfide outer shell:

[0153] On the basis of Step 3, the temperature was continuously raised until it stabilized at 290 °C, 5 milliliters of the zinc precursor solution was injected, and 1.5 milliliters of the n-dodecanethiol solution was injected at a rate of 3 milliliters per hour and maintained for 70 minutes to complete the coating of the zinc sulfide outer shell.

[0154] Step 5, cooling and purification to obtain core-shell structured indium phosphide quantum dots:

[0155] On the basis of Step 4, the temperature is naturally cooled to room temperature. The solution cooled to room temperature is added with 10 mL of n-hexane, and then centrifuged at 10,000 rpm for 4 minutes to remove impurities. The obtained supernatant is mixed with ethanol in a ratio of 1:1 and centrifuged at 10,000 rpm for 4 minutes. The resulting precipitate is dissolved in 2 mL of n-hexane, and then 2 mL of ethanol is added for precipitation. It is centrifuged at 10,000 rpm for 3 minutes, and the supernatant is discarded to retain the precipitate, thus completing the preparation of the core-shell structured indium phosphide quantum dots.

[0156] Figure 18 It is the UV absorption spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this comparative example. Figure 19 It is the fluorescence emission spectrum picture of the core-shell structured indium phosphide quantum dots prepared in this comparative example. It can be seen that the fluorescence emission peak position of the core-shell structured indium phosphide quantum dots prepared under this comparative example is at 527 nm, the full width at half maximum is 57 nm, and the quantum efficiency is about 42%. Compared with Example 2 with the same dosage, the quantum efficiency of Example 2 is 82.3% and the full width at half maximum is only 37 nm. There is a significant difference in the effects of the quantum dots prepared using the traditional phosphorus source.

[0157] Figure 20 It is the lifetime decay curve graph of Comparative Example 2. Figure 21 It is the TEM image of the core-shell structured indium phosphide quantum dots prepared in this comparative example. It can be seen that the distribution uniformity of the quantum dots is poor and their average particle size is about 6.6 nm.

[0158] Figure 22 It is the XRD pattern of the quantum dots prepared in the examples and comparative examples. Among them, it can be seen that the quantum dots prepared in Examples 1-3 have three significant zinc blende characteristic peaks of the (111) plane, (220) plane, and (311) plane, and there are no other impurity peaks. By comparison, it can be seen that the XRD peaks obtained in Example 2 are higher, indicating that the quantum dots obtained in Example 2 have better crystallinity.

[0159] The performances of the quantum dots prepared in the examples and comparative examples are summarized in Table 1. It can be seen from Examples 1, 2, and 3 that as the content of the Zn source increases, the emission peak position of the quantum dots shows a red shift. When the amount of the Zn source injected during the growth of ZnS is 5 mL, its full width at half maximum is the narrowest, which is 37 nm, as Figure 7 shown, and it can be seen from the Figure 9 TEM image that the particle size distribution of the quantum dots is uniform and their fluorescence quantum yield is as high as 82.3%. It shows that increasing the amount of the Zn source during the growth of ZnS helps to grow a thicker ZnS shell layer, thereby restricting the epitaxy of excitons to the shell layer and enhancing the quantum efficiency of the core-shell structured indium phosphide quantum dots.

[0160] Further increasing the amount of the Zn source, it can be seen that when the amount of the Zn source reaches 6 mL, its full width at half maximum becomes wider and the quantum efficiency decreases. The reason may be that the ZnS shell is too thick, resulting in an increase in strain between the shells, which in turn leads to an increase in defects between the shells, an increase in non-radiative recombination, and a decline in the luminescence performance of the quantum dots. However, overall, it is still better than the comparative example.

[0161] By comparing the example with Comparative Example 1, it can be seen that the InP core quantum dots without the coated shell of the indium phosphide quantum dots based on tri-pyrrolidinophosphine as the phosphorus source have poor luminescence performance, with a quantum efficiency of only 6.2% and a wide full width at half maximum, indicating that coating the shell helps reduce defects, enhance the radiative recombination efficiency, and improve the luminescence performance of the indium phosphide quantum dots.

[0162] Comparing Comparative Example 2 with Example 2, it can be seen that the full width at half maximum of the comparative example is wider and its luminescence efficiency is relatively low. Therefore, we can conclude that the indium phosphide quantum dots with a core-shell structure synthesized using tri-pyrrolidinophosphine as the phosphorus source have better performance than those using tris(dimethylamino)phosphine as the phosphorus source, and we have obtained indium phosphide quantum dots with excellent luminescence performance based on tri-pyrrolidinophosphine as the phosphorus source through optimization.

[0163] Table 1 Summary of the luminescence performance of the quantum dots prepared in the examples and comparative examples

[0164] Serial number Fluorescence emission peak position Full width at half maximum Quantum efficiency Example 1 510 nm 52 nm 58％ Example 2 525 nm 37 nm 82.3％ Example 3 541 nm 48 nm 51.6％ Comparative example 1 512 nm 55 nm 6.2％ Comparative example 2 527 nm 57 nm 42％

Claims

1. A preparation method of indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine, characterized in that, Including the steps: Step 1: Dissolve a zinc source, a selenium source, and a sulfur source in a solvent respectively to form a zinc precursor solution, a selenium precursor solution, and a sulfur precursor solution; Dissolve tripyrrolidinophosphine in a solvent to form a phosphorus precursor solution; Step 2: Dissolve and mix indium halide and zinc halide, heat to a first temperature for reaction, then heat to a second temperature and add the phosphorus precursor solution for reaction to obtain an indium phosphide core solution; Step 3: Continuously add the zinc precursor solution, the selenium precursor solution, and the sulfur precursor solution to the indium phosphide core solution in Step 2, heat to a third temperature for reaction to obtain an indium phosphide solution coated with a zinc selenide sulfur intermediate shell; Step 4: Heat the solution in Step 3 to a fourth temperature, add the zinc precursor solution and a dodecanethiol solution for reaction to obtain a quantum dot solution, and obtain the core-shell structured indium phosphide quantum dots through purification.

2. The preparation method of the indium phosphide quantum dot with a core-shell structure based on tripyrrolidinophosphine according to claim 1, wherein The solvent used in the zinc precursor solution includes any one or more of octadecene, oleylamine, oleic acid, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene; The solvents used in the selenium precursor solution and the sulfur precursor solution are independently selected from any one or more of trioctylphosphine, octadecene, oleylamine; The solvent used in the phosphorus precursor solution includes any one or more of oleylamine, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine.

3. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, wherein, In Step 1, the preparation of the precursor solution is obtained by heating and dissolving the raw materials in a solvent; The heating temperature of the zinc precursor solution is 100 - 150 °C; The heating temperatures of the selenium precursor solution and the sulfur precursor solution are both 60 - 90 °C; The heating temperature of the phosphorus precursor solution is 30 - 70 °C.

4. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, characterized in that, The zinc source includes any one or more of zinc stearate, zinc acetate, zinc oxide, zinc chloride, zinc bromide, zinc iodide; The selenium source includes any one or more of selenium powder, selenium dichloride, selenium tetrachloride, phenylselenium chloride, selenol, and diselenide; The sulfur source includes any one or more of sulfur powder, dodecanethiol, octanethiol.

5. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, characterized in that, The indium halide includes any one or more of indium iodide, indium bromide, indium chloride; the zinc halide includes any one or more of zinc bromide, zinc iodide, zinc chloride; The solvent used in Step 2 includes any one or more of oleylamine, dodecane, hexadecane, hexadecylamine, octadecylamine, octylamine, oleic acid, octadecene.

6. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, wherein, In Step 2, the molar ratio of indium halide, zinc halide, and tripyrrolidinophosphine is 1:(4.5 - 5.5):(3.4 - 5); The first temperature is 120 - 140 °C, and the second temperature is 190 - 200 °C; The reaction time at the first temperature is 30 - 60 min; the reaction time after adding the phosphorus precursor solution is 10 - 20 min.

7. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, characterized in that, In Step 3, the molar ratio of the zinc source in the zinc precursor solution, the selenium source in the selenium precursor solution, the sulfur source in the sulfur precursor solution to indium halide is (9 - 12.5):(2.5 - 5.5):(2.5 - 5.5):1; The third temperature is 260 - 280 °C, and the reaction time is 90 - 120 min.

8. The preparation method of the indium phosphide quantum dots with a core-shell structure based on tripyrrolidinophosphine according to claim 1, characterized in that, In Step 4, the molar ratio of the zinc source, 1-dodecanethiol to indium halide in the zinc precursor solution is (2.5 - 5.5):(9 - 19):1; The fourth temperature is 290 - 300 °C, and the reaction is carried out for 60 - 80 min.

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