Zn < 2 + >-lanthanide ion complex co-doped CIZS quantum dot and method thereof

Abstract

The invention discloses a Zn < 2 + >-lanthanide ion complex co-doped CIZS quantum dot and a method thereof. The method comprises the following steps: (1) preparing a multi-element sulfide quantum dot; (2) preparing a lanthanide ion complex; (3) preparing CIZS quantum dots coated with Zn < 2 + >; and (4) preparing the lanthanide ion complex doped CIZS (at) ZnS quantum dot. The luminescent property of the quantum dot is improved by utilizing rich f-f electron transition energy level of lanthanide elements and through additional absorbed light quantum energy transfer or through structure doping on the surface of the quantum dot. The key point is that the problem that the lanthanide ions (Ln < 3 + >) are difficult to dope the sulfenyl quantum dots is overcome in a breakthrough manner, so that the lanthanide ions (Ln < 3 + >) and the complex thereof are structurally doped and permeated to the CuInZnS quantum dots. The ZnS-coated lanthanide ion complex-doped CuInZnS quantum dot is prepared by the following steps of: performing Zn < 2 + > coating on the surface of the quantum dot under proper reaction conditions by selecting a combination of an organic small molecule ligand and lanthanide ions to form a lanthanide ion complex, and then introducing the lanthanide ion complex to obtain the ZnS-coated lanthanide ion complex-doped CuInZnS quantum dot.

Description

Technical Field

[0001] The present invention relates to surface modification of quantum dots, and in particular to a Zn 2+ -Lanthanide ion complex co-doped CIZS quantum dots and methods thereof. Background Art

[0002] Quantum dots (QDs) are nanoparticles with excellent optical properties, and their size is usually between 1 and 10 nm. When quantum dots are excited by light, carriers recombine and produce fluorescence. Although quantum dots have many optical advantages, they still have some shortcomings such as unstable optical properties, more non-radiative recombination, and surface defects that easily localize electronic states. By modifying the surface of quantum dots to reduce the non-radiative luminescence centers and surface defects of quantum dots, the energy levels are continuously discretized and the carrier motion is more orderly, thereby enhancing the quantum confinement effect. Due to the lanthanide ions (Ln 3+ ) has a rich energy level structure and can absorb and emit light of specific wavelengths. Introducing them into quantum dots can not only optimize the energy level structure of quantum dots, but also regulate the various luminescence mechanisms of quantum dots. However, because the outer electrons of lanthanide elements easily form chemical bonds with oxygen, it is difficult for them to react directly with sulfides. Therefore, preparing lanthanide ions into lanthanide ion complexes is an effective solution. By selecting suitable ligands to change the electron cloud and chemical activity of lanthanide elements, the number of active sites is increased, providing more opportunities for rare earth ions to react with sulfides. This type of doped quantum dot has a wide range of application prospects, such as lighting, photocatalysis, sensors, light-emitting diodes, thermoelectric devices, photothermal therapy, bioimaging, solar concentrators, environmentally friendly absorbers, etc., providing a scientific basis and theoretical foundation for expanding the absorption spectrum range of devices, reducing band gaps and excitation energy states, and improving photoelectric conversion efficiency and color performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a Zn 2+ -Lanthanide ion complex co-doped CIZS quantum dots and methods thereof.

[0004] The technical solutions of the present invention are as follows: A Zn 2+ - A method for preparing CIZS quantum dots co-doped with lanthanide ion complexes, comprising the following steps: (1) Preparation of polysulfide quantum dots: Cuprous iodide and sulfur powder are dissolved in octadecene and oleylamine by hot injection to generate a Cu2S substrate; then, an indium acetate precursor and a nano-zinc oxide precursor are introduced into the Cu2S substrate by a two-step cation exchange method to generate CIZS quaternary quantum dots; (2) Preparation of lanthanide ion complexes: lanthanide element ions and dicarbonyl ligands acetylacetone or its derivatives and 1,10-phenanthroline are fully mixed in a sufficient amount of anhydrous ethanol in a certain proportion, the solution is adjusted to neutrality, and the lanthanide ion complex is generated after a period of reaction; (3) Preparation of Zn 2+ Coated CIZS quantum dots: dissolve zinc acetylacetonate and thiourea in 2-ethylhexanoic acid and triethylene glycol dimethyl ether to obtain a ZnS precursor; then inject the ZnS precursor into the surface of the CIZS quantum dots in step (1) at a certain temperature to form CIZS@ZnS core-shell structure quantum dots. (4) Preparation of lanthanide ion complex-doped CIZS@ZnS quantum dots: The lanthanide ion complex in step (2) is doped into the ZnS in step (3) at high temperature. 2+ Among the modified CIZS quantum dots, ZnS-coated lanthanide ion complex-doped CuInZnS quantum dots were obtained.

[0005] In the preparation method, in step (1), the proportion of substances used is as follows: octadecene: 8-10 mL, oleylamine: 1-3 mL, sulfur powder: 0.1-0.3 mmol, cuprous iodide: 0.03-0.05 mmol, indium acetate: 0.3-0.5 mmol, nano zinc oxide: 0.8-1.2 mmol, which are completely dissolved at high temperature to generate CIZS quantum dots.

[0006] The preparation method, in step (2), the preparation method of the lanthanide ion complex is: europium (Eu), terbium (Tb), ytterbium (Yb), cerium (Ce) or lanthanum (La) chloride and acetylacetone or its derivatives, 1,10-phenanthroline are fully mixed in anhydrous ethanol in a ratio of 1:3:1, and then ammonia water is added dropwise to adjust the pH value to 7-8, and stirred at room temperature for 3-4 hours to obtain five lanthanide ion complexes of EAP / TAP / YAP / CAP / LAP, and freeze-dried to obtain phosphor.

[0007] The preparation method, in step (3), the ZnS precursor preparation method is: 0.8-1.2 mmol of zinc acetylacetonate is dissolved in 0.4-0.6 ml of 2-ethylhexanoic acid and 1-3 ml of triethylene glycol dimethyl ether to obtain Zn 2+ Precursor; then dissolve 1-3mmol thiourea in 2-4 ml of triethylene glycol dimethyl ether to obtain S 2- Precursor. Zn 2+ Precursor and S 2- The precursors are fully mixed to obtain a ZnS precursor.

[0008] The preparation method comprises the following steps: in step (4), the ZnS mixed solution in step (3) is injected into the surface of the CIZS quantum dots in step (1) at 100°C, the reaction system is heated to 140-160°C, the lanthanide ion complex is doped therein, and then the temperature is raised to 220-240°C and maintained for 4-5 hours to obtain ZnS-coated lanthanide ion complex-doped CuInZnS quantum dots.

[0009] Zn prepared according to any one of the preparation methods 2+ -CIZS quantum dots co-doped with lanthanide ion complexes.

[0010] Since lanthanide ions (Ln 3+ ) is oxygen-philic and sulfur-phobic, and its outer electrons easily form chemical bonds with oxygen, making it difficult to react directly with sulfides. Therefore, the key is to prepare a Ln 3+ complexes to overcome the difficulty of lanthanide ions in doping sulfur-based quantum dots, thereby realizing Ln 3+ Therefore, the combination of organic small molecule ligands and lanthanide ions is selected to form Ln 3+ complexes to change the electron cloud and chemical activity of lanthanide ions, increase their active sites, enhance their coordination ability, and provide more opportunities for lanthanide ions to react with sulfide quantum dots. 3+ Complex ligands are an effective means of complexation. Since dicarbonyl ligands contain two carbonyl groups in their structure, they can form complexes with various metal ions with good stability and unique spectral properties. They can be used as ligands to participate in reactions in the fields of coordination chemistry, photochemistry, electrochemistry, etc., and have a wide range of applications. 3+ The outer electron orbital is easy to form chemical bonds with oxygen but difficult to react directly with sulfide. In this invention, lanthanide elements are prepared into Ln 3+ Surface doping of quantum dots with complexes as a solution.

[0011] This patent adopts the above technical points and has the following beneficial effects: (1) Improvement of optical properties: Under the optimal doping reaction conditions, different lanthanide ion complexes (Eu 3+ , Tb 3+ , Yb 3 + , Ce 3+ , La 3+) doped CIZS and CIZS@ZnS quantum dots have unique fluorescence emission peaks. The emission wavelength of quantum dots continues to blueshift before and after doping, the photoluminescence continues to increase, and the light absorption capacity continues to improve. This is because the introduction of lanthanide ion complexes continuously changes the energy level distribution and crystal structure of quantum dots. Lanthanide ions have rich energy level structures, and their excited states have a good match with the excited state energy levels of quantum dots. By comparison, Eu 3+ The doping of Eu 3+ The 4f electron transitions efficiently transfer energy to the quantum dots, increasing the energy difference and shifting the quantum dots, improving their optical properties. Similarly, the absorption edge shifts toward shorter wavelengths, absorbing more photons. The synergistic effect of the lanthanide ion complex and the quantum dots enhances light energy capture, increasing the probability of radiative recombination and reducing non-radiative recombination. Through this energy transfer mechanism, the absorbed energy is transferred to the luminescent centers of the CIZS and CIZS@ZnS quantum dots, enhancing luminescence intensity and improving overall luminous efficiency.

[0012] (2) Improve the purity of luminescence color: The doping of lanthanide ion complexes can effectively reduce the additional luminescence wavelength caused by factors such as lattice defects, surface states and impurities in quantum dots, thereby improving the purity of luminescence color. Specifically, the doping of lanthanide ion complexes can adjust and repair the lattice structure to a certain extent through its interaction with surrounding atoms, reduce the number and size of lattice defects, thereby reducing the interference of these defect energy levels on the electron-hole pair recombination process and reducing the additional luminescence wavelength. At the same time, the ZnS shell modifies the surface of the quantum dots, forming a relatively stable structure on the surface, reducing the number of surface dangling bonds and defects, and reducing the capture effect of surface states on electron-hole pairs, thereby further reducing the additional luminescence wavelength and improving the purity of the luminescence color. In addition, the synergistic effect between lanthanide ion complexes and quantum dots can also fine-tune the electronic structure and energy level distribution of quantum dots, making the recombination process of electron-hole pairs more concentrated, further improving the purity of the luminescence color.

[0013] (3) Improvement of electrical properties: After doping with lanthanide ion complexes, the lattice structure and electron cloud distribution of CIZS and CIZS@ZnS quantum dots are affected, thereby improving their electrical properties. On the one hand, the ionic radius of lanthanide elements is different from that of the original ions in CIZS quantum dots. When they enter the lattice, they will cause lattice distortion. This lattice distortion will change the interaction force between atoms in the lattice and the electron cloud distribution to a certain extent, causing the scattering mechanism of carriers in the lattice to change. Specifically, appropriate lattice distortion can weaken the interaction between carriers and lattice vibrations, reduce the scattering effect of lattice vibrations on carriers, and thus improve carrier mobility. On the other hand, the doping of lanthanide ion complexes can precisely control the band structure of CIZS and CIZS@ZnS quantum dots, so that they can better meet the needs of different application scenarios. Specifically, the ff electronic configuration of lanthanide elements has a rich energy level structure. When doped into CIZS and CIZS@ZnS quantum dots, it will introduce new impurity energy levels into the band structure of quantum dots. These impurity energy levels can reside within the quantum dot's bandgap, forming specific energy relationships with the conduction and valence bands, thereby altering the quantum dot's band structure and electronic transition characteristics. By controlling the doping concentration and distribution of lanthanide ion complexes, the location and number of these impurity energy levels can be precisely adjusted, enabling fine-tuning of the band structure of CIZS and CIZS@ZnS quantum dots to meet the band structure requirements of diverse applications, such as solar cells and optoelectronic devices.

[0014] (4) Enhanced chemical stability: After doping with lanthanide ion complexes, they can form a relatively stable structure on the surface and inside of CIZS and CIZS@ZnS quantum dots, thereby reducing the chemical reaction activity of surface atoms with the external environment. On the one hand, Zn 2+ It has strong sulfur affinity. When ZnS is coated into CIZS quantum dots, part of Zn 2+ They preferentially bind to surface sulfur atoms, forming a dense ZnS shell-like structure on the quantum dot surface. This layer effectively isolates surface atoms from the external environment, reducing the chance of chemical reactions with substances like water molecules and oxygen, thereby enhancing the chemical stability of the quantum dots. Furthermore, the doping of lanthanide ion complexes can interact with surrounding atoms, adjusting and optimizing the quantum dot lattice structure to a certain extent. This reduces the number and size of lattice defects, thereby reducing their impact on the chemical reactivity of surface atoms and further enhancing the chemical stability of the quantum dots.

[0015] (5) Improve structural stability: The lattice structure of CIZS quantum dots is adjusted and optimized by doping with lanthanide ion complexes and coating with ZnS shells, which reduces lattice distortion and enhances the interaction between atoms, thereby improving structural stability. On the one hand, the ionic radius of lanthanide elements is large. When doped into CIZS quantum dots, they occupy a certain position in the lattice, causing local expansion of the lattice. This lattice expansion will change the interaction force and distance between atoms in the lattice to a certain extent, making the lattice spacing smaller and the lattice structure more stable. On the other hand, the ff electronic configuration of lanthanide elements can interact with the electron cloud of surrounding atoms, further adjusting the lattice structure. When the ZnS shell is coated into the quantum dots, it can better integrate into the lattice, fill some defect sites in the lattice, reduce lattice distortion, make the interaction between atoms more uniform and stable, and thus improve structural stability. This synergistic effect can make the lattice structure of quantum dots more stable and orderly, thereby improving its structural stability and reliability in various application scenarios and reducing performance degradation and failure problems caused by structural changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 (a) PL and (b) UV-vis spectra of CIZS quantum dots doped with different lanthanide ion complexes.

[0017] Figure 2 (a) PL and (b) UV-vis spectra of the CIZS@ZnS quantum dots doped with different lanthanide ion complexes.

[0018] Figure 3 PL spectra of Eu-doped CIZS@ZnS quantum dots at different reaction temperatures, times and Zn-Eu doping molar ratios.

[0019] Figure 4 These are the PL and UV-vis spectra of pure CIZS, CIZS-Eu, and CIZS@ZnS-Eu quantum dots of the materials of the present invention under optimal reaction conditions.

[0020] Figure 5 (a) XRD and (b) FTIR spectra of the materials CIZS, CIZS-Eu and CIZS@ZnS-Eu quantum dots of the present invention.

[0021] Figure 6 (a) is the EDAX spectrum of pure CIZS, CIZS-Eu and CIZS@ZnS-Eu quantum dots of the present invention, and (bg) is the element distribution diagram of CIZS@ZnS-Eu quantum dots in Example 5 under SEM.

[0022] Figure 7TEM (a1-c1) and HRTEM (a2-c2) of pure CIZS, CIZS-Eu and CIZS@ZnS-Eu quantum dots of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to specific embodiments. Example 1: Preparation of polysulfide quantum dots by hot injection

[0024] First, weigh about 0.04 mmol of copper iodide (Cu + ) and 0.2 mmol sulfur powder (S 2- ) as a precursor, dissolved in 9 ml of solvent octadecene (ODE) and 2 ml of ligand oleylamine (OAM), heated to 100°C and reacted for about 10 minutes to synthesize Cu2S quantum dots as the matrix material. Using amine ligands to modify the surface of quantum dots can make the quantum dots stably dispersed in the oil phase, obtaining oil-soluble quantum dots with better optical properties. Secondly, 0.4 mmol of indium acetate (In) was introduced into the Cu2S quantum dots at 120-140°C. 3+ ) precursor, then heated to 160-180℃ for about 10 min to synthesize CuInS2 quantum dots. After the solution stabilized, cooled to 100℃ and 1 mmol zinc oxide (Zn 2+ ) precursor was introduced into the system, and then the temperature was raised to 250℃ for about 10 min, and quaternary CIZS quantum dots were obtained by cation exchange method. Figure 7 (a1, a2) are TEM and HRTEM images of CIZS quantum dots. The morphology is close to spherical and the dispersion is uniform and good. The average size of the sample is about 3.28 nm. The lattice spacing (d value) of CIZS quantum dots measured by observing the lattice fringes is about 0.328 nm. Example 2: Preparation of different lanthanide ion complexes

[0025] 0.1 mol / L of lanthanide ions (e.g., europium chloride (EuCl36H2O3), terbium chloride (TbCl36H2O3), ytterbium chloride (YbCl36H2O3), cerium chloride (CeCl36H2O3), and lanthanum chloride (LaCl36H2O3)) and the dicarbonyl ligands acetylacetone (ACAC) or its derivatives and 1,10-phenanthroline (Phen) were gradually added to a flask containing approximately 50 ml of anhydrous ethanol (EA). The molar ratio of lanthanide chloride to ACAC and Phen was 1:3:1. 10-20 ml of aqueous ammonia was then added to adjust the pH of the solution to 7-8. The solution was stirred at room temperature for 3-4 hours. Gradually, the solution became turbid. After washing with EA and centrifuging three times, the resulting lanthanide ion complexes of Eu(ACAC)3phen (EAP), Tb(ACAC)3phen (TAP), Yb(ACAC)3phen (YAP), Ce(ACAC)3phen (CAP), and La(ACAC)3phen (LAP) were dried under vacuum to form rare earth complex phosphors. Subsequently, different rare earth complexes (approximately 0.025 g) were dissolved in OAM (1 mL) and ODE (5 mL) to prepare different lanthanide ion complex solutions using the same ligands and solvent as the CIZS quantum dots in Example 1. These solutions overcome the lanthanide's affinity for oxygen and sulfide repellency, and were then used to dope quantum dots before and after shelling, forming doped quantum dots with a variety of luminescence mechanisms. Example 3: CIZS quantum dots doped with different lanthanide ion complexes

[0026] CIZS quantum dots were nucleated and grown at 250 °C. After fully reacting for 10 minutes, the three-necked flask was lifted and cooled. The cooling was stopped when it reached 100 °C, and the reaction was maintained for 10 minutes to stabilize the CIZS quantum dots. The CIZS quantum dots were then heated to 140-160 °C, and 0.1 mol / L of the lanthanide ion complexes (EAP / TAP / YAP / CAP / LAP) in Example 2 were doped into the CIZS quantum dot reaction system. The temperature was then raised to 230 °C and fully reacted for 4 hours. The solution eventually emitted an orange-red light under ultraviolet light, indicating that the rare earth ions had fully reacted with the CIZS QDs to form lanthanide ion-doped quantum dots (CIZS-Eu / CIZS-Tb / CIZS-Yb / CIZS-Ce / CIZS-La). Figure 1 (a) shows the different lanthanide ion complexes (Eu / CIZS-Tb / CIZS-Yb / CIZS-Ce / CIZS-La) under the same conditions. 3+ / Tb 3+ / Yb 3 + / Ce 3+ / La 3+The PL spectrum of CIZS quantum dots doped with lanthanide ions shows a fluorescence wavelength of about 610 nm, and there is no emission peak unique to rare earth ions in this band, which indicates that lanthanide ions can act as sensitizers, absorb light of a specific wavelength, and transfer energy to quantum dots, thereby enhancing the band-edge luminescence of quantum dots. Figure 1 (b) UV-vis spectra of CIZS quantum dots doped with different lanthanide ion complexes. The band edge absorption of quantum dots is enhanced after doping, which is due to the electronic transition ability of lanthanide ions from the valence band to the conduction band. Figure 7 (b1, b2) are TEM and HRTEM images of CIZS-Eu quantum dots. 3+ The introduction of leads to an enhanced confinement effect, and the core size of the quantum dots is reduced due to limited doping, and the average size is reduced to about 2.33 nm. At the same time, doping introduces more surface defects, making the particle distribution irregular. By observing the lattice fringes, the lattice spacing (d value) of CIZS-Eu quantum dots is measured to be about 0.233 nm.

[0027] Example 4: Zn 2+ Surface modification of CIZS quantum dots.

[0028] Dissolve 1 mmol of zinc acetylacetonate (Zn(ACAC)2) in 0.5 ml of 2-ethylhexanoic acid and 1 ml of triethylene glycol dimethyl ether (TEDM). Heat the solution to dissolve and obtain Zn 2+ Precursor solution. Then 1.2 mmol thiourea (S) was dissolved in 3 ml TEDM, placed in an oil pan and stirred at 60 °C to dissolve, and S 2- Precursor solution. 2+ Precursor solution and S 2- After the precursor solution is fully dissolved, it is mixed to form ZnS quantum dots. After the CIZS quantum dots are synthesized in Example 1, the reaction solution is cooled. When it reaches 100°C, the cooling is stopped and the reaction is allowed to proceed for 10 minutes. Subsequently, ZnS quantum dots are introduced into the reaction system to coat the ZnS shell, forming CIZS@ZnS core-shell quantum dots. During this period, the solution color is observed to gradually change from bright red to orange-red.

[0029] Example 5: Lanthanide Ion Complex Doping with Zn 2+ Modified CIZS quantum dots.

[0030] In Example 4, after the CIZS quantum dots were coated with the ZnS shell, the solution was heated to 140-160°C, and the lanthanide ion complex precursor solution prepared in Example 2 was slowly added dropwise to the reaction system. The reaction system was then heated to 230°C for a full reaction of 4 hours. The solution eventually emitted a clear orange light under a UV lamp, indicating that the lanthanide ion complex had fully reacted with the CIZS@ZnS quantum dots to form doped core-shell quantum dots (CIZS@ZnS-Eu / CIZS@ZnS-Tb / CIZS@ZnS-Yb / CIZS@ZnS-Ce / CIZS@ZnS-La). Figure 2 (a) shows the PL spectra of CIZS@ZnS quantum dots doped with different lanthanide ion complexes under the same conditions. The fluorescence wavelength is approximately 575 nm, and the fluorescence intensity is further improved compared to the quantum dots not coated with ZnS in Example 3. This is because the ZnS shell changes the surface state of the quantum dots, passivates their surface defects, and reduces non-radiative recombination, thereby further improving the luminescence efficiency of the quantum dots under the doping of lanthanide ions. Figure 2 (b) UV-vis spectra of CIZS@ZnS quantum dots doped with different lanthanide ion complexes under the same conditions. Compared with the quantum dots without ZnS coating in Example 3, a new UV absorption peak appears. This is due to the Zn in the shell. 2+ Under the induction of lanthanide ions, they react with oxygen vacancies in the environment to form new ZnO quantum dots. The absorption edge of bulk ZnO is about 373 nm (band gap energy is 3.37 eV). Due to the quantum confinement effect, its absorption peak is slightly blue-shifted to 370 nm. Figure 3 (ac) shows Eu 3+ The optimal reaction conditions for doping CIZS@ZnS QDs, namely reaction temperature, reaction time and the shell material Zn 2+ and dopant Eu 3+ The results of eight groups of control experiments under each condition show that under the reaction conditions of reaction temperature 230 ° C, reaction time 4 h and Zn-Eu doping molar ratio 1: 0.05 mmol, CIZS@ZnS-Eu quantum dots have the best emission spectrum characteristics. Figure 4 (a, b) shows the PL and UV-vis spectra of pure CIZS, CIZS-Eu and CIZS@ZnS-Eu quantum dots under the optimal reaction conditions. Compared with the quantum dots without ZnS coating in Example 3, the emission wavelength of the quantum dots coated with ZnS is further blue-shifted, the fluorescence intensity is increased by about 1.55 times, and the quantum yield is increased by about 25%. This is because Eu 3+It has a rich energy level structure, and its excited state is well matched to the excited state energy level of the quantum dots. Its 4f electron transitions can efficiently transfer energy to the quantum dots, increasing their energy difference and absorbing more photons, thereby increasing the quantum dots' light energy capture and utilization efficiency, and thus improving the quantum dots' optical properties. Figure 5 (a, b) shows the XRD and FTIR spectra of pure CIZS, CIZS-Eu, and CIZS@ZnS-Eu quantum dots. Compared with the CIZS quantum dots in Example 1, the CIZS-Eu quantum dots in Example 3 exhibit significant changes in the lattice, with a significantly smaller grain size. In contrast, the CIZS@ZnS-Eu quantum dots in Example 5 exhibit diffraction peaks characteristic of ZnO, enhancing the crystal strength. Simultaneously, after doping, the infrared absorbance of the quantum dots increases, indicating that the rare earth ions introduce additional luminescence centers, increasing photon absorption and emission. Figure 6 (a) is the EDAX spectrum of CIZS, CIZS-Eu, and CIZS@ZnS-Eu quantum dots after electron beam excitation, confirming the presence and content of S, In, Cu, Zn, and Eu. By detecting the peak position and intensity of each element, S (Kα ~2.31 keV), Cu (Kα ~ 8.04 keV), Zn (Kα ~ 8.63 keV), In (Lα ~ 3.29 keV), and Eu (Lα ~ 4.85 keV) were obtained. Compared with the CIZS quantum dots in Example 1, the CIZS-Eu in Example 3 detected an additional peak of Eu element. The other peaks and intensities did not change significantly, which is due to the fact that Eu 3+ Compared with the CIZS quantum dots in Example 1, the CIZS@ZnS-Eu in Example 5 not only detected more peaks of Eu elements, but also significantly improved the intensity of Zn elements. This is due to the fact that Zn in Example 4 2+ of superposition. Figure 6 (bg) are the element distribution diagrams of CIZS@ZnS-Eu quantum dots in Example 5 under SEM. The diagram shows that the distribution of S, In, Cu, Zn and Eu elements is relatively uniform, and there is no obvious aggregation or missing area. The surface sample composition has good uniformity. Figure 7 (c) is the TEM image of CIZS@ZnS-Eu quantum dots. ZnS shell layer is added to the surface of CIZS quantum dots in Example 1 and then Ln is doped. 3+ The complex was prepared to obtain the CIZS@ZnS-Eu quantum dots in Example 5. The size increased to about 3.23 nm, and due to the influence of interface strain, the core size was slightly compressed, the band gap increased, and the quantum confinement effect was enhanced, resulting in a blue shift in the fluorescence wavelength. The lattice spacing (d value) of the CIZS@ZnS-Eu quantum dots was measured to be approximately 0.323 nm by observing the lattice fringes.

[0031] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A Zn 2+ - A method for preparing CIZS quantum dots co-doped with lanthanide ion complexes, characterized in that: The steps include: (1) Preparation of polysulfide quantum dots: Cuprous iodide and sulfur powder are dissolved in octadecene and oleylamine by hot injection to generate a Cu2S substrate; then, an indium acetate precursor and a nano-zinc oxide precursor are introduced into the Cu2S substrate by a two-step cation exchange method to generate CIZS quaternary quantum dots; (2) Preparation of lanthanide ion complexes: lanthanide element ions and dicarbonyl ligands acetylacetone or its derivatives and 1,10-phenanthroline are fully mixed in a sufficient amount of anhydrous ethanol in a certain proportion, the solution is adjusted to neutrality, and the lanthanide ion complex is generated after a period of reaction; (3) Preparation of Zn 2+ Coated CIZS quantum dots: zinc acetylacetonate and thiourea are dissolved in 2-ethylhexanoic acid and triethylene glycol dimethyl ether to obtain a ZnS precursor; the ZnS precursor is then injected into the surface of the CIZS quantum dots in step (1) at a certain temperature to form CIZS@ZnS core-shell structure quantum dots; (4) Preparation of lanthanide ion complex-doped CIZS@ZnS quantum dots: The lanthanide ion complex in step (2) is doped into the ZnS in step (3) at high temperature. 2+ Among the modified CIZS quantum dots, ZnS-coated lanthanide ion complex-doped CuInZnS quantum dots were obtained.

2. The preparation method according to claim 1, characterized in that In step (1), the proportion of substances used is as follows: octadecene: 8-10 mL, oleylamine: 1-3 mL, sulfur powder: 0.1-0.3 mmol, cuprous iodide: 0.03-0.05 mmol, indium acetate: 0.3-0.5 mmol, nano zinc oxide: 0.8-1.2 mmol, which are completely dissolved at high temperature to form CIZS quantum dots.

3. The preparation method according to claim 1, characterized in that In step (2), the lanthanide ion complex is prepared by: thoroughly mixing chloride of europium (Eu), terbium (Tb), ytterbium (Yb), cerium (Ce) or lanthanum (La) and acetylacetone or its derivatives, and 1,10-phenanthroline in anhydrous ethanol in a ratio of 1:3:1, then adding ammonia water dropwise to adjust the pH value to 7-8, and stirring at room temperature for 3-4 hours to obtain five lanthanide ion complexes of EAP / TAP / YAP / CAP / LAP, and freeze-drying to obtain phosphor.

4. The preparation method according to claim 1, characterized in that In step (3), the ZnS precursor is prepared by dissolving 0.8-1.2 mmol of zinc acetylacetonate in 0.4-0.6 ml of 2-ethylhexanoic acid and 1-3 ml of triethylene glycol dimethyl ether to obtain ZnS. 2+ Precursor; then dissolve 1-3 mmol thiourea in 2-4 ml triethylene glycol dimethyl ether to obtain S 2- Precursor; Zn 2+ Precursor and S 2- The precursors are fully mixed to obtain a ZnS precursor.

5. The preparation method according to claim 1, characterized in that In step (4), the ZnS mixed solution in step (3) is injected into the surface of the CIZS quantum dots in step (1) at 100°C, and the reaction system is heated to 140-160°C to dope the lanthanide ion complex therein, and then heated to 220-240°C and maintained for 4-5 hours to obtain ZnS-coated lanthanide ion complex-doped CuInZnS quantum dots.

6. Zn prepared by the preparation method according to any one of claims 1 to 5 2+ -CIZS quantum dots co-doped with lanthanide ion complexes.

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