A surface pre-passivation method of indium phosphide quantum dots and a preparation method of core-shell structure quantum dots
By pre-passivating indium phosphide quantum dots with hexafluorophosphate ions, various surface defect problems were solved, efficient interface passivation and shell growth were achieved, and the optical performance of indium phosphide quantum dots was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies struggle to simultaneously and synergistically passivate various surface defects in indium phosphide quantum dots, such as uncoordinated indium dangling bonds and oxide layers, resulting in limited improvement in optical performance. Furthermore, the shell growth is uneven, and the interface lattice mismatch is severe.
Pre-passivation with hexafluorophosphate ions (PF6-) is used to passivate indium defects by forming In-F bonds and partially etching the oxide layer, creating a low-defect surface and reducing interface defects during subsequent shell growth.
It significantly improves the photoluminescence quantum yield of indium phosphide quantum dots, reduces interface defects, and enhances the optical performance of the core-shell structure.
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Figure CN122144667A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor nanomaterials technology, and in particular to a surface prepassivation method for indium phosphide quantum dots and a method for preparing core-shell structured quantum dots. Background Technology
[0002] Indium phosphide quantum dots (IPDs) are considered ideal alternatives to cadmium-containing quantum dots due to their cadmium-free nature and excellent luminescence properties. Their bulk material possesses a direct band gap and a suitable bandgap, theoretically exhibiting superior optoelectronic properties. However, the high specific surface area of IPD crystals readily leads to abundant surface defects during synthesis, such as phosphorus vacancies, indium dangling bonds, and native oxide layers. These defect states introduce deep energy levels into the band gap, becoming highly efficient nonradiative recombination centers. This not only significantly reduces the photoluminescence quantum yield of the core itself but also causes serious consequences in subsequent core-shell structure fabrication. These surface defects act as nucleation sites for heteroepitaxial growth, resulting in uneven shell growth, exacerbated interfacial lattice mismatch, and the formation of interfacial defects.
[0003] Traditional pretreatment of indium phosphide quantum dot cores typically relies on single pathways such as hydrofluoric acid etching or zinc precursor passivation, aiming to remove surface oxides or saturated indium dangling bonds, respectively. However, these methods have a single mechanism of action, often requiring precise control of conditions in application, and may introduce secondary impurities or trigger surface reconstruction. Therefore, existing strategies struggle to simultaneously and synergistically passivate various defects on the surface of indium phosphide quantum dot cores, such as uncoordinated indium dangling bonds and oxide layers, becoming a key bottleneck restricting further improvements in their optical performance. Summary of the Invention
[0004] The purpose of this invention is to provide a surface pre-passivation method for indium phosphide quantum dots and a method for preparing core-shell structured quantum dots, based on the pre-passivation of indium phosphide quantum dots by introducing PF6. - Ions are used to passivate indium defects on the surface and partially remove the oxide layer, thereby providing a high-quality interface for subsequent shell growth and preparing core-shell quantum dots with high luminescence performance.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: One of the technical solutions of this invention provides a surface pre-passivation method for indium phosphide quantum dots, comprising the following steps: Indium precursor, hexafluorophosphate, and ligand are mixed, degassed, and heated to 200-220°C under a nitrogen atmosphere. Phosphine precursor is then added, and the reaction proceeds to obtain indium phosphide quantum dots.
[0006] The second technical solution of the present invention provides indium phosphide quantum dots prepared by the above-mentioned surface pre-passivation method.
[0007] The third technical solution of the present invention provides an indium phosphide-based core-shell quantum dot, wherein the indium phosphide-based core-shell quantum dot has a core-shell structure, the core being the aforementioned indium phosphide quantum dot, and the shell being a double-shell structure, including an inner shell layer covering the surface of the indium phosphide quantum dot and an outer shell layer covering the surface of the inner shell layer; the inner shell layer is a zinc selenide shell layer, and the outer shell layer is a zinc sulfide shell layer.
[0008] The fourth technical solution of the present invention provides a method for preparing the above-mentioned indium phosphide-based core-shell quantum dots, comprising the following steps: (1) Mix indium precursor, zinc precursor, hexafluorophosphate and ligand, degas and heat to 200~220℃ under nitrogen atmosphere, add phosphine precursor and react to obtain indium phosphide quantum dots; (2) Under a nitrogen atmosphere, a selenium precursor was added to indium phosphide quantum dots and a reaction was carried out to obtain indium phosphide quantum dots coated with a zinc selenide shell. (3) Under a nitrogen atmosphere, sulfur precursors are added to indium phosphide quantum dots coated with zinc selenide shells to carry out the reaction and obtain indium phosphide core-shell quantum dots.
[0009] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes PF6 - F produced by the hydrolysis of ions under reaction conditions - Ions specifically bind to uncoordinated indium sites (dangling bonds) on the surface to form In-F bonds, effectively solving the indium defect problem that is difficult to address with traditional passivation strategies. - Ions can also partially etch and remove the native oxide layer (such as In2O3 and In2PO) on the surface of the InP core. x This reduces the formation of interface defects from the source. Pre-passivation creates a low-defect InP core surface, significantly reducing interface defects caused by interfacial lattice mismatch and heterogeneous nucleation during subsequent ZnSe / ZnS shell epitaxial growth. After PF6… − The photoluminescence quantum yield of InP / ZnSe / ZnS core-shell quantum dots prepared after pre-passivation treatment is significantly improved. Attached Figure Description
[0010] Figure 1 (a) Schematic diagram of the synthesis of indium phosphide / zinc selenide / zinc sulfide quantum dots treated with HBPyU-PF6; (b) UV-Vis absorption spectra and photoluminescence (PL) spectra of InP quantum dots obtained at different HBPyU-PF6 concentrations; (c) XRD patterns of InP cores and InP / zinc selenide / zinc sulfide quantum dots with and without HBPyU-PF6.
[0011] Figure 2(a) is a TEM image of InP, (b) is a TEM image of InP with 0.1 mmol HBPyU-PF6, and (c) is a TEM image of InP with 0.15 mmol HBPyU-PF6. The inset shows the high-resolution TEM images and particle size distribution histograms.
[0012] Figure 3 XPS plots of InP quantum dots with and without HBPyU-PF6.
[0013] Figure 4 (a) is a TEM image of InP / ZnSe / ZnS HBPyU-PF6; (b) are the UV-Vis absorption and photoluminescence spectra of InP / ZnSe / ZnS core-shell quantum dots with and without HBPyU-PF6 treatment, with the inset showing the corresponding photographs of the quantum dots under UV light; (c) are different amounts of PF6. - Photoluminescence emission peaks of treated InP / zinc selenide / zinc sulfide quantum dots; (d) for different amounts of PF6 - PLQY and FWHM of treated InP / ZnSe / ZnS core-shell quantum dots; (e) Time-resolved photoluminescence decay of InP / ZnSe / ZnS core-shell quantum dots with and without HBPyU-PF6. Detailed Implementation
[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0015] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0016] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0017] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.
[0018] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0019] The room temperature mentioned in this invention is calculated as 25±2℃.
[0020] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.
[0021] This invention provides a surface pre-passivation method for indium phosphide quantum dots, comprising the following steps: Indium precursor, hexafluorophosphate, and ligand are mixed, degassed, and heated to 200-220°C under a nitrogen atmosphere. Phosphine precursor is then added, and the reaction proceeds to obtain indium phosphide quantum dots.
[0022] In some embodiments of the present invention, indium precursor, hexafluorophosphate, and ligand are added sequentially to a reaction vessel for degassing. After degassing, the mixture is rapidly heated to 200-220°C while maintaining a nitrogen atmosphere. Then, phosphine precursor is rapidly added, and the reaction is carried out at 200-220°C. After the reaction is completed, the mixture is naturally cooled to room temperature, centrifuged, and purified to obtain indium phosphide quantum dots.
[0023] In this invention, the hexafluorophosphate comprises (benzotriazol-1-yl)-N,N,N',N'-dipyrrolithourea hexafluorophosphate; the indium precursor comprises indium chloride; the ligand is a mixture of tri-n-octylphosphine and oleylamine; the volume ratio of tri-n-octylphosphine to oleylamine is 1:25~35, preferably 1:30; the phosphine precursor is obtained by mixing tris(dimethylamino)phosphine and 1-octadecene; the volume ratio of tris(dimethylamino)phosphine to 1-octadecene is 0.7~0.8:1.
[0024] In the synthesis of indium phosphide quantum dots, hexafluorophosphate is introduced as a surface passivating agent, especially (benzotriazol-1-yl)-N,N,N',N'-dipyrrolidohexafluorophosphate. The pre-passivation step is carried out simultaneously in the synthesis of indium phosphide quantum dots, that is, the hexafluorophosphate is mixed with the indium precursor and ligand in the reaction system, and degassed by heating before the phosphorus precursor is injected.
[0025] In this invention, the molar ratio of the indium precursor to hexafluorophosphate is 1:0.4 to 0.8, for example, it can be 1:0.4, 1:0.5, 1:0.6, 1:0.7 or 1:0.8; the amount ratio of the indium precursor to the ligand is 0.25 mmol: 4.3 to 4.9 mL, preferably 0.25 mmol: 4.65 mL; the amount ratio of the indium precursor to the phosphine precursor is 0.25 mmol: 0.4 to 0.5 mL, preferably 0.25 mmol: 0.44 mL.
[0026] In this invention, the degassing is performed by purging with nitrogen gas at a temperature of 40-60°C, such as 40°C, 45°C, 50°C, 55°C, or 60°C, for a purging time of 50-70 minutes, such as 50 minutes, 55 minutes, 60 minutes, 65 minutes, or 70 minutes; the reaction temperature is 200-220°C, such as 200, 210, or 220°C, for a reaction time of 50-70 minutes, such as 50 minutes, 55 minutes, 60 minutes, 65 minutes, or 70 minutes.
[0027] In this invention, the centrifugation is performed by adding hexane and anhydrous ethanol to the cooled solution and then centrifuging; the volume ratio of hexane to anhydrous ethanol is 1:5; the centrifugation speed is 6000 r / min and the centrifugation time is 5 min.
[0028] In this invention, the purification process involves repeating the centrifugation process twice, for a total of three times, to obtain purified indium phosphide quantum dots.
[0029] The present invention also provides indium phosphide quantum dots prepared by the above-mentioned surface pre-passivation method.
[0030] The present invention also provides an indium phosphide-based core-shell quantum dot, wherein the indium phosphide-based core-shell quantum dot has a core-shell structure, the core being the aforementioned indium phosphide quantum dot, and the shell being a double-shell structure, including an inner shell layer covering the surface of the indium phosphide quantum dot and an outer shell layer covering the surface of the inner shell layer; the inner shell layer is a zinc selenide shell layer, and the outer shell layer is a zinc sulfide shell layer.
[0031] This invention also provides a method for preparing the above-mentioned indium phosphide-based core-shell quantum dots, comprising the following steps: (1) Mix indium precursor, zinc precursor, hexafluorophosphate and ligand, degas and heat to 200~220℃ under nitrogen atmosphere, add phosphine precursor and react to obtain indium phosphide quantum dots; (2) Under a nitrogen atmosphere, a selenium precursor was added to indium phosphide quantum dots and a reaction was carried out to obtain indium phosphide quantum dots coated with a zinc selenide shell. (3) Under a nitrogen atmosphere, sulfur precursors are added to indium phosphide quantum dots coated with zinc selenide shells to carry out the reaction and obtain indium phosphide core-shell quantum dots.
[0032] In this invention, the zinc precursor includes zinc chloride; the ratio of the zinc precursor to the indium precursor is 15.2:1.
[0033] In this invention, the selenium precursor is obtained by mixing selenium powder and oleylamine. The mixing is performed by ultrasonic vibration at 50°C for 30 min, and the ratio of selenium powder to oleylamine is 4 mmol: 10 mL. The molar ratio of selenium powder to indium precursor is 4.8:1; the addition rate of selenium precursor is 0.05 mL / min, and the shell coating is completed simultaneously after injection; the reaction temperature in step (2) is 235℃, and heating is stopped after injection.
[0034] In this invention, the sulfur precursor is obtained by mixing sulfur powder and oleylamine, with a sulfur powder to oleylamine ratio of 4 mmol: 10 mL, and the mixing is performed by ultrasonic vibration at 50°C for 30 min. The molar ratio of sulfur powder to indium precursor is 2.8:1; the addition rate of sulfur precursor is 0.05 mL / min, and the shell coating is completed simultaneously after injection; the reaction temperature in step (3) is 265℃, and heating is stopped after injection.
[0035] After step (3) is completed, the mixture is allowed to cool naturally to room temperature, then centrifuged and purified to obtain indium phosphide core-shell quantum dots.
[0036] The centrifugation is performed by adding hexane and anhydrous ethanol to the cooled solution and centrifuging; the volume ratio of hexane to anhydrous ethanol is 1:5; the centrifugation speed is 6000 r / min and the centrifugation time is 5 min.
[0037] In this invention, the purification process involves repeating the centrifugation process twice, for a total of three times, to obtain purified indium phosphide quantum dots.
[0038] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0039] Example 1 (1) Preparation of phosphine precursor: 0.19 mL of tris(dimethylamino)phosphine ((DMA)3P) was mixed with 0.25 mL of 1-octadecene (ODE) to obtain phosphine precursor; (2) Degassing: In a 50 mL three-necked flask, add 0.25 mmol InCl, 0.15 mmol (benzotriazol-1-yl)-N,N,N',N'-dipyrrolidinyl urea hexafluorophosphate (HBPyU-PF6), 0.15 mL tri-n-octylphosphine (TOP) and 4.5 mL oleylamine (OAm) in sequence, and degas by purging with nitrogen at 50 °C for 60 min; (3) Synthesis: After degassing, maintain a nitrogen atmosphere in the three-necked flask and heat rapidly to 200°C. When the temperature reaches 200°C, rapidly inject 0.44 mL of phosphine precursor into the three-necked flask and maintain the reaction at 200°C for 60 min. After the reaction is completed, allow it to cool naturally to room temperature. (4) Centrifugation: Add 5 mL of n-hexane and 25 mL of anhydrous ethanol to the cooled solution from step (3), and centrifuge at 6000 r / min for 5 min in a centrifuge. (5) Purification: Repeat the centrifugation process of step (4) twice, for a total of three times, to obtain purified InP quantum dots, denoted as InP with HBPyU−PF6.
[0040] Example 2 (1) Preparation of phosphine precursor: 0.19 mL of (DMA)3P was mixed with 0.25 mL of ODE to obtain the phosphine precursor; (2) Preparation of selenium precursor: 4 mmol of selenium powder was dissolved in 10 mL of oleylamine and ultrasonically vibrated at 50 °C for 30 min to obtain the selenium precursor, denoted as Se-OAm; (3) Preparation of sulfur precursor: 4 mmol of sulfur powder was dissolved in 10 mL of oleylamine and ultrasonically vibrated at 50 °C for 30 min to obtain sulfur precursor, denoted as S-OAm; (4) Degassing: In a 50 mL three-necked flask, add 0.25 mmol InCl, 3.8 mmol ZnCl2, 0.15 mmol HBPyU−PF6, 0.15 mL TOP and 4.5 mL oleylamine in sequence, and degas by purging with nitrogen at 50 °C for 60 min; (5) Synthesis: After degassing, maintain a nitrogen atmosphere in the three-necked flask and heat rapidly to 200°C. When the temperature reaches 200°C, rapidly inject 0.44 mL of phosphine precursor into the three-necked flask and maintain the reaction at 200°C for 60 min. (6) Coating with zinc selenide shell: After reacting for 60 min, 0.25 mL of Se-OAm was injected into the reaction system, and then the reaction system was heated to 235 °C. Se-OAm was injected at a rate of 0.25 mL every 5 minutes for a total of 3 mL. (7) Coating with zinc sulfide shell: After the zinc selenide shell is coated, the reaction system is heated to 265°C and S-OAm is injected at a rate of 0.25 mL every 5 min, for a total of 1.75 mL. After the reaction is completed, it is naturally cooled to room temperature; (8) Centrifugation: 5 mL of n-hexane and 25 mL of anhydrous ethanol are added to the cooled solution and centrifuged at 6000 r / min for 5 min in a centrifuge; (9) Purification: Repeat the centrifugation process twice more, for a total of three times, to obtain purified InP / ZnSe / ZnS core-shell quantum dots, denoted as InP / ZnSe / ZnS HBPyU-PF6.
[0041] Example 3 The only difference from Example 1 is that the amount of HBPyU-PF6 added is 0.1 mmol.
[0042] Example 4 The only difference from Example 1 is that the amount of HBPyU-PF6 added is 0.2 mmol.
[0043] Example 5 The only difference from Example 2 is that the amount of HBPyU-PF6 added is 0.1 mmol.
[0044] Example 6 The only difference from Example 2 is that the amount of HBPyU-PF6 added is 0.2 mmol.
[0045] Comparative Example 1 The only difference from Example 2 is that HBPyU-PF6 is not added, denoted as InP / ZnSe / ZnS.
[0046] Comparative Example 2 The only difference from Example 1 is that HBPyU-PF6, denoted as InP, is not added.
[0047] Test case Figure 1 (b) shows the UV-Vis absorption and photoluminescence (PL) spectra of InP quantum dots obtained at different HBPyU-PF6 concentrations. It can be seen that as the HBPyU-PF6 concentration increases from 0.1 mmol to 0.15 mmol, the first exciton absorption peak of InP quantum dots with HBPyU-PF6 redshifts from 665 nm to 673 nm, and the PL emission peak redshifts from 734 nm to 743 nm. The full width at half maximum (FWHM) are 45 nm and 48 nm, respectively, indicating that PF6... - The introduction of ions effectively passivated surface defects and promoted quantum dot growth; however, when the concentration increased to 0.2 mmol, the absorption characteristics disappeared and PL was completely quenched, indicating that excessive F...- Ions caused excessive etching and crystal structure destruction. (c) shows the XRD patterns of InP cores and InP / zinc selenide / zinc sulfide quantum dots with and without HBPyU-PF6. It can be seen that the InP core sample without HBPyU-PF6 exhibits typical zinc sphalerite diffraction peaks at 26.3°, 43.6°, and 51.7°, corresponding to the (111), (220), and (311) crystal planes, respectively. In addition, In2O3 diffraction peaks also appear at 30.6°, 35.5°, and 51°, indicating the presence of oxidation in the reaction system. After treatment with HBPyU-PF6, the In2O3 diffraction peaks disappeared, and InF3-related diffraction peaks appeared, confirming that PF6... - F produced by hydrolysis - Ions coordinate with indium defect sites to form In-F bonds, effectively removing the oxide layer and passivating surface defects. After coating with a ZnSe / ZnS shell, the InF3 diffraction peaks disappear, and all diffraction peaks shift to higher angles and become significantly broader, indicating that elemental interdiffusion occurred at the core / shell interface, forming a gradient alloy interface layer. This not only alleviates lattice mismatch but also further promotes defect passivation.
[0048] Figure 2 (a) is a TEM image of InP, (b) is a TEM image of InP with 0.1 mmol HBPyU-PF6, and (c) is a TEM image of InP with 0.15 mmol HBPyU-PF6. The inset shows the high-resolution TEM images and particle size distribution histogram, which shows that all InP quantum dots exhibit clear lattice fringes, indicating good crystallinity. The average particle size of the InP cores without HBPyU-PF6 treatment was 6.3 ± 0.8 nm, with a relative size distribution of 12.7%. After treatment with 0.1 mmol and 0.15 mmol HBPyU-PF6, the average particle size of the InP quantum dots decreased to 5.8 ± 0.7 nm and 5.9 ± 0.8 nm, respectively, with relative size distributions of 12.1% and 13.6%. The reduction in particle size is attributed to PF6. - The etching effect of ions effectively removed the surface oxide layer, resulting in a more uniform core size. High-resolution TEM analysis showed that the interplanar spacings of the untreated, 0.1 mmol, and 0.15 mmol HBPyU-PF6 treated samples were 0.342 nm, 0.335 nm, and 0.341 nm, respectively, all close to the standard interplanar spacing (0.338 nm) of the InP(111) crystal plane, further confirming the presence of PF6. - The treatment optimized the surface quality while maintaining the integrity of the crystal structure.
[0049] Figure 3The XPS plots of InP quantum dots with and without HBPyU-PF6 show that after HBPyU-PF6 treatment, the In 3d peak shifts towards lower binding energies (from 451.9 / 444.3 eV to 451.4 / 443.9 eV), indicating an increase in electron cloud density around indium atoms, confirming the F... - Ions coordinate with uncoordinated indium sites on the surface to form In-F bonds. In the p 2p spectrum, the treated sample shows InPO x The peak intensity decreased significantly, indicating that PF6 - The surface oxide layer was effectively etched and partially removed. The F 1s spectrum appeared only in the treated sample, with two peaks at 683.4 eV and 686.6 eV attributed to In-F and PF bonds, respectively, confirming PF6. - It has decomposed and participated in surface coordination. In the O 1s spectrum, the untreated sample showed multiple peaks (corresponding to In2O3, InOOH / In(OH)3, and InPO3), while the treated sample showed a single peak, further proving that oxides and phosphorus-containing defect states were effectively removed. In the N 1s spectrum, NH4 + Both the NH2 peak and the NH2 peak shifted to lower binding energies, indicating that ammonium ions and amino ligands participated in surface passivation.
[0050] Figure 4 (a) shows a TEM image of InP / ZnSe / ZnS HBPyU-PF6. It can be seen that after treatment with 0.15 mmol HBPyU-PF6, the average particle size of the quantum dots coated with the ZnSe / ZnS shell is 7.9 ± 0.4 nm, with a relative size distribution of 5.1%. High-resolution TEM shows a lattice spacing of 0.326 nm, which highly matches the standard spacing of the ZnSe(111) crystal plane (0.327 nm), indicating successful epitaxial growth of the shell without obvious stacking faults. (b) shows the UV-Vis absorption and photoluminescence spectra of InP / zinc selenide / zinc sulfide quantum dots after and without HBPyU-PF6 treatment. The inset shows the corresponding photographs of the quantum dots under UV light. It can be seen that after treatment with PF6... - After treatment, the absorption and emission peaks of the sample exhibited a red shift (emission peak shifted from 635 nm to 645 nm), and PLQY increased from 30% to 40%. The inset shows that the treated sample exhibited a brighter red emission under UV light; (c) shows different amounts of PF6. - The photoluminescence emission peaks of the treated InP / zinc selenide / zinc sulfide quantum dots show that they are different from those of the untreated PF6 quantum dots. - Compared to the treated samples, those treated with PF6 -The emission peaks of all treated samples exhibited a red shift. As the amount of HBPyU-PF6 increased from 0.1 mmol to 0.15 mmol, the emission peak position gradually red-shifted from ~635 nm (untreated) to 645 nm. When the amount was further increased to 0.2 mmol, due to excess F... - Excessive etching of ions leads to the destruction of the crystal structure and the disappearance of the fluorescence emission peak; (d) shows different amounts of PF6. - The PLQY and FWHM of the treated InP / zinc selenide / zinc sulfide quantum dots show that PLQY varies with PF6. - The effect increased with increasing dosage, reaching a peak of 40% at 0.15 mmol, compared to no PF6 added. - At that time, the FWHM slightly broadened from 62 nm to 65 nm, indicating that certain compositional or structural inhomogeneities were introduced during the interfacial alloying process; (e) shows the time-resolved photoluminescence decay of InP / zinc selenide / zinc sulfide quantum dots with and without HBPyU-PF6, indicating that PF6... - After treatment, the average fluorescence lifetime decreased from 106.4 ns to 88.2 ns, of which the fast lifetime component ( The lifetime decreased significantly from 61.3 ns to 31.3 ns, and its contribution ratio also decreased, while the slow lifetime component ( The contribution of ) increased from 32.7% to 40.5%, indicating that some defect states that were originally non-radiative recombination were transformed into efficient radiative recombination centers, which is the main reason for the improvement of PLQY.
[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for surface pre-passivation of indium phosphide quantum dots, characterized in that, Includes the following steps: Indium precursor, hexafluorophosphate, and ligand are mixed, degassed, and heated to 200-220°C under a nitrogen atmosphere. Phosphine precursor is then added, and the reaction proceeds to obtain indium phosphide quantum dots.
2. The surface pre-passivation method for indium phosphide quantum dots according to claim 1, characterized in that, The hexafluorophosphate comprises (benzotriazol-1-yl)-N,N,N',N'-dipyrrolithourea hexafluorophosphate; the indium precursor comprises indium chloride; the ligand is a mixture of tri-n-octylphosphine and oleylamine; the volume ratio of tri-n-octylphosphine to oleylamine is 1:25~35; the phosphine precursor is obtained by mixing tris(dimethylamino)phosphine and 1-octadecene; the volume ratio of tris(dimethylamino)phosphine to 1-octadecene is 0.7~0.8:
1.
3. The surface pre-passivation method for indium phosphide quantum dots according to claim 1, characterized in that, The molar ratio of indium precursor to hexafluorophosphate is 1:0.4~0.8; the amount ratio of indium precursor to ligand is 0.25mmol:4.3~4.9mL; the amount ratio of indium precursor to phosphine precursor is 0.25mmol:0.4~0.5mL.
4. The surface pre-passivation method for indium phosphide quantum dots according to claim 1, characterized in that, The degassing is performed by purging with nitrogen gas at a temperature of 40-60°C for 50-70 minutes; the reaction temperature is 200-220°C for 50-70 minutes.
5. Indium phosphide quantum dots prepared by the surface prepassivation method of indium phosphide quantum dots according to any one of claims 1 to 4.
6. An indium phosphide-based core-shell quantum dot, characterized in that, The indium phosphide-based core-shell quantum dot has a core-shell structure, wherein the core is the indium phosphide quantum dot as described in claim 5, and the shell is a double-shell structure, including an inner shell layer covering the surface of the indium phosphide quantum dot and an outer shell layer covering the surface of the inner shell layer; the inner shell layer is a zinc selenide shell layer, and the outer shell layer is a zinc sulfide shell layer.
7. A method for preparing indium phosphide-based core-shell quantum dots according to claim 6, characterized in that, Includes the following steps: (1) Mix indium precursor, zinc precursor, hexafluorophosphate and ligand, degas and heat to 200~220℃ under nitrogen atmosphere, add phosphine precursor and react to obtain indium phosphide quantum dots; (2) Under a nitrogen atmosphere, a selenium precursor was added to indium phosphide quantum dots and a reaction was carried out to obtain indium phosphide quantum dots coated with a zinc selenide shell. (3) Under a nitrogen atmosphere, sulfur precursors are added to indium phosphide quantum dots coated with zinc selenide shells to carry out the reaction and obtain indium phosphide core-shell quantum dots.
8. The preparation method according to claim 7, characterized in that, The zinc precursor includes zinc chloride; the ratio of the zinc precursor to the indium precursor is 15.2:
1.
9. The preparation method according to claim 7, characterized in that, The selenium precursor is obtained by mixing selenium powder and oleylamine; the molar ratio of selenium powder to indium precursor is 4.8:1; the addition rate of the selenium precursor is 0.05 mL / min; the reaction temperature in step (2) is 235 °C.
10. The preparation method according to claim 7, characterized in that, The sulfur precursor is obtained by mixing sulfur powder and oleylamine; the molar ratio of sulfur powder to indium precursor is 2.8:1; the addition rate of the sulfur precursor is 0.05 mL / min; the reaction temperature in step (3) is 265℃.