Long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres and their preparation method and application

Abstract

The present invention relates to a long-life, highly luminescent gold-copper cluster composite microsphere, a preparation method, and an application thereof. The microsphere is an ordered assembly of gold and copper clusters formed by self-assembly, with a diameter of 3 to 8 μm. The preparation method comprises the following steps: thoroughly mixing propylthiouracil and HAuCl4 in an aqueous solution, adding NaOH to obtain a gold nanocluster solution, mixing the gold nanocluster solution with a Cu(NO3)2 solution, and then adding Cu(NO3)2 to form a gold nanocluster solution. 2+ Free propylthiouracil is reduced to form copper clusters, which then undergo multi-level self-assembly with gold clusters, first forming nanowires, which in turn assemble into microspheres. The resulting microsphere assemblies have a novel structure and stable properties, emitting red phosphorescence with a lifetime exceeding 30 microseconds and a quantum yield exceeding 20%. They can be used to fabricate white light-emitting diodes, broadening the application prospects of metal nanoclusters in lighting.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic luminescent materials, and in particular relates to a long-life, highly luminescent gold cluster-copper cluster composite microsphere, a preparation method thereof, and an application thereof in white light LEDs. Background Art

[0002] Metal nanoclusters, represented by gold, silver, and copper, are an emerging class of inorganic-organic hybrid materials that have attracted widespread attention due to their unique structure and properties. Metal nanoclusters consist of a metal core and protective ligands. The metal core is typically composed of a few to dozens of metal atoms, is extremely small (<2 nm), and possesses a high surface energy. Therefore, it is necessary to modify the metal core with sulfur-containing small molecules as protective ligands to stabilize its structure. The most attractive feature of metal nanoclusters is their photoluminescence properties, characterized by a large Stokes shift (~200 nm), easily tunable emission wavelength, and long luminescence lifetime. However, a significant drawback of metal nanoclusters as luminescent materials is their typically extremely weak luminescence intensity and extremely low quantum yield, which hinders their practical application. To address the low luminescence intensity of metal nanoclusters, several effective control strategies have been explored, among which aggregation-induced emission and doping with heterogeneous metals are the most commonly used.

[0003] By modifying the ligand structure, inducing poor solvents, adjusting the solution pH, and other methods, metal nanoclusters can be aggregated, thereby limiting the thermal motion of the ligand molecules and enhancing the luminescence intensity of the nanoclusters. This phenomenon has been reported in many literatures (Angew. Chem. Int. Ed., 2020, 59, 9934–9939; Angew. Chem. Int. Ed. 2022, 61, e202200180), and some patent documents also disclose several metal nanocluster materials with aggregation-induced luminescence (CN112933247A; CN115197694A; CN107254307B). However, the structure of metal nanoclusters contains multiple metal atoms and organic ligands, and the interactions between clusters are very complex. The aggregation behavior is difficult to control, making gold nanoclusters prone to forming irregular aggregates or precipitates, which limits the degree of luminescence enhancement. Therefore, developing a method to regulate the aggregation behavior of metal nanoclusters and constructing an ordered metal nanocluster aggregate structure is the key to further improving the luminescence performance of such materials.

[0004] Doping metal nanoclusters with dissimilar metals to construct composite nanoclusters can also improve the luminescence performance of such materials to a certain extent (Angew. Chem. Int. Ed., 2021, 60, 4551–4554; JACS Au, 2023, 3, 565–574). In addition, CN105602554A discloses a gold-doped copper nanocluster self-assembled fluorescent material, a preparation method, and its application in LED packaging. The self-assembled fluorescent material is self-assembled by copper nanoclusters and doped with gold (gold accounts for 0.003% to 80% of the total metal element molar ratio). Through doping, a phosphor with continuously adjustable fluorescence color is obtained. However, since the luminescence mechanism of metal nanoclusters themselves is unclear, the introduction of dissimilar metals will significantly change the energy level structure and charge transfer mechanism of the nanoclusters, making the luminescence effect brought about by dissimilar metal doping difficult to predict, and the preparation of composite nanoclusters with enhanced luminescence is somewhat difficult. At the same time, existing strategies for regulating nanoclusters by doping with dissimilar metals often require the use of organic solvents, which increases environmental pressure.

[0005] In summary, in the field of metal nanocluster research, whether it is aggregation-induced emission or the doping of heterogeneous metals, there are still unresolved problems. The luminescence performance of metal nanoclusters still has a lot of room for improvement, and structurally ordered metal nanocluster aggregates are still very scarce. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, especially the lack of ordered aggregates of metal nanoclusters, the difficulty in controlling the luminescence intensity of heterogeneous metal composite nanoclusters, and the environmental problems caused by the need to add strong reducing agents and organic solvents, the present invention provides a gold cluster-copper cluster composite microsphere with high luminescence quantum yield and long luminescence lifetime and its application in white light LEDs.

[0007] This method uses propylthiouracil as a protective ligand to prepare gold nanoclusters. By directly doping the gold nanocluster solution with copper ions, the copper ions are reduced and copper nanoclusters are generated in situ. The resulting gold-copper cluster complex not only has a regular micron-sphere structure but also exhibits high-intensity, long-life luminescence properties, providing a valuable red phosphorescent material for the preparation of white light LEDs.

[0008] The technical solutions of the present invention are as follows:

[0009] The invention discloses a long-life strong luminescent gold cluster-copper cluster composite micron ball, which is a spherical assembly formed by tightly weaving nanowires. The nanowires are self-assembled from gold clusters and copper clusters.

[0010] According to the present invention, preferably, the core of the gold cluster is composed of zero-valent gold and positive monovalent gold, and the protective ligand is propylthiouracil; the core of the copper cluster is composed of zero-valent copper and positive monovalent copper, and the protective ligand is propylthiouracil.

[0011] According to the present invention, the molecular structural formula of propylthiouracil is:

[0012]

[0013] According to the present invention, preferably, the diameter of the nanowire is 20 to 80 nm; preferably, the diameter of the spherical assembly is 3 to 8 μm.

[0014] According to the present invention, preferably, the molar ratio of gold to propylthiouracil in the gold cluster is (0.03-0.6):1; for example: 0.05:1, 0.1:1, 0.15:1, 0.3:1, 0.5:1;

[0015] Preferably, the molar ratio of copper to propylthiouracil in the copper cluster is (0.2-3):1.

[0016] According to the present invention, preferably, in the gold cluster-copper cluster composite microspheres, the molar ratio of gold to copper is 1:(1.2-50), for example: 3:1, 5:1, 10:1, 20:1, 30:1, 40:1.

[0017] According to the present invention, preferably, the gold cluster-copper cluster composite microspheres have the following optical properties: phosphorescence emission wavelength is between 550 and 750 nm, luminescence lifetime is greater than 30 microseconds, and luminescence quantum yield is greater than 20%.

[0018] According to the present invention, a method for preparing the above-mentioned long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres is also provided, comprising the following steps:

[0019] (1) uniformly mixing an aqueous suspension of propylthiouracil and an aqueous solution of HAuCl4 and allowing the mixture to stand to obtain a mixed solution;

[0020] (2) adding NaOH solution to the mixed solution and mixing uniformly to obtain a gold nanocluster solution;

[0021] (3) adding Cu(NO3)2 solution to the gold nanocluster solution, shaking, and then standing at a constant temperature to obtain a suspension of gold cluster-copper cluster composite microspheres;

[0022] (4) The suspension of the gold cluster-copper cluster composite microspheres is centrifuged and then vacuum dried to obtain a solid powder of the gold cluster-copper cluster composite microspheres.

[0023] According to the present invention, preferably, the concentration of the propylthiouracil suspension used in step (1) is 20 to 80 mmol / L, and the concentration of the HAuCl4 aqueous solution used is 10 to 50 mmol / L;

[0024] Preferably, the molar ratio of propylthiouracil to HAuCl4 is 1:(0.03-0.6); for example: 0.05:1, 0.1:1, 0.15:1, 0.3:1, 0.5:1;

[0025] Preferably, the standing time is more than 20 hours, more preferably 24-60 hours.

[0026] According to the present invention, preferably, in step (2), the concentration of the NaOH solution used is 1 to 5 mol / L;

[0027] Preferably, the amount of NaOH solution added is controlled until the gold nanocluster solution becomes clear and transparent.

[0028] According to the present invention, preferably, in step (3), the concentration of the Cu(NO3)2 solution used is 0.05 to 0.2 mol / L;

[0029] Preferably, the molar ratio of Cu(NO3)2 to HAuCl4 is (1.2-50):1, for example: 3:1, 5:1, 10:1, 20:1, 30:1, 40:1;

[0030] Preferably, the constant temperature standing temperature is 0-50° C., and the standing time is more than 20 hours, more preferably 24-60 hours.

[0031] According to the present invention, a method for preparing long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres, a preferred embodiment, comprises the following steps:

[0032] (1) Mix 4 mL of propylthiouracil suspension and 1 mL of HAuCl4 aqueous solution, shake vigorously, and let stand for more than 24 hours;

[0033] (2) Add 0.2 mL of NaOH solution to the mixture after standing, shake vigorously, transfer to a volumetric flask, dilute the mixture to 10 mL with deionized water, and shake well to obtain a yellow transparent gold nanocluster solution;

[0034] (3) 5 mL of gold nanocluster solution was mixed with 0.6 mL of Cu(NO3)2 solution, and after vigorous shaking, the mixture was placed in a constant temperature incubator and allowed to stand at 0-50°C for more than 24 hours to obtain a suspension of gold cluster-copper cluster composite microspheres;

[0035] (4) After centrifuging the suspension of the gold cluster-copper cluster composite microspheres, the suspension was vacuum-dried at room temperature to obtain a solid powder of the gold cluster-copper cluster composite microspheres.

[0036] According to the present invention, there is also provided the use of the above-mentioned long-life, highly luminescent gold cluster-copper cluster composite microspheres in white light LEDs.

[0037] According to the present invention, a white light LED comprising the above-mentioned long-life, highly luminescent gold cluster-copper cluster composite microspheres is also provided.

[0038] According to the present invention, a method for preparing a white light LED comprising the above-mentioned long-life, high-luminescence gold cluster-copper cluster composite microspheres comprises the following steps:

[0039] The solid powder of gold cluster-copper cluster composite microspheres was mixed with BaMgAl 10 O 17 :Eu 2+ Phosphor and (Ba,Sr)2SiO4:Eu 2+ The phosphors are mixed and coated onto a 395nm near-ultraviolet GaN chip to produce an LED. Driven by a current of 20 to 140 mA, the LED emits white light.

[0040] According to the present invention, preferably, the solid powder of gold cluster-copper cluster composite microspheres, BaMgAl 10 O 17 :Eu 2+ Phosphor, (Ba, Sr) 2 SiO 4: Eu 2+ The mass ratio of the three phosphors is: 1.8~2.2:1.2~1.6:1.

[0041] Principle of the present invention:

[0042] HAuCl4 is reduced by propylthiouracil in aqueous solution to generate gold nanoclusters with zero-valent gold and positive one-valent gold as the core and propylthiouracil as the protective ligand. Adding NaOH helps to fully dissolve and stabilize the gold nanoclusters. When Cu(NO3)2 is added, the free propylthiouracil in the gold nanocluster solution converts Cu 2+ The reduction reaction is to zero-valent copper and positive monovalent copper, generating copper clusters with propylthiouracil as a protective ligand. These copper clusters interact strongly with the existing gold clusters in the solution through Cu(I)…Au(I) metallophilic interactions and hydrogen bonding. Driven by these non-covalent interactions, the gold and copper clusters undergo multi-level self-assembly, first into nanowires, which then assemble into microspheres. The formation of the microsphere assembly enhances charge transfer between the ligand and the metal, and between Cu(I) and Au(I), while also restricting the ligand's thermal motion and reducing non-radiative transitions. These combined effects result in a strong phosphorescence emission from the microspheres.

[0043] According to the present invention, the ratio of the protective ligand, HAuCl₄, NaOH, and Cu(NO₃)₂, their respective concentrations, order of addition, and reaction time are crucial in the preparation of gold-copper cluster composite microspheres. These conditions were creatively selected through extensive experimentation. Improper substrate concentrations or order of addition will not yield highly luminescent microsphere assemblies.

[0044] The beneficial effects of the present invention are as follows:

[0045] The gold-copper cluster composite microspheres of the present invention are structurally ordered aggregates with stable properties. They exhibit red phosphorescence with an emission wavelength between 550 and 750 nm, a long luminescence lifetime exceeding 30 microseconds, and a high luminescence quantum yield exceeding 20%, making them excellent red-light emitting materials.

[0046] 2. The preparation method of the gold cluster-copper cluster composite microspheres provided by the present invention is simple to operate, does not require the addition of strong reducing agents and organic solvents, is environmentally friendly, has easy-to-control preparation conditions, and has good experimental repeatability.

[0047] 3. The gold cluster-copper cluster composite microspheres provided by the present invention can be used to prepare white light LEDs, broadening the application prospects of metal nanoclusters in the field of lighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a scanning electron microscope (SEM) photograph of the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0049] Figure 2 This is the X-ray photoelectron spectrum of Au in the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0050] Figure 3 This is the X-ray photoelectron spectrum of Cu in the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0051] Figure 4 This is the MALDI-TOF mass spectrum of the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0052] Figure 5 This is the steady-state fluorescence spectrum of the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0053] Figure 6 This is the time-resolved fluorescence decay curve of the gold cluster-copper cluster composite microspheres prepared in Example 1.

[0054] Figure 7 This is an SEM photograph of the gold cluster-copper cluster composite microspheres prepared in Example 2.

[0055] Figure 8 This is the steady-state fluorescence spectrum of the gold cluster-copper cluster composite microspheres prepared in Example 2.

[0056] Figure 9 This is the time-resolved fluorescence decay curve of the gold cluster-copper cluster composite microspheres prepared in Example 2.

[0057] Figure 10 This is an SEM photograph of the gold cluster-copper cluster composite microspheres prepared in Example 3.

[0058] Figure 11 This is the steady-state fluorescence spectrum of the gold cluster-copper cluster composite microspheres prepared in Example 3.

[0059] Figure 12 This is the time-resolved fluorescence decay curve of the gold cluster-copper cluster composite microspheres prepared in Example 3.

[0060] Figure 13 These are electroluminescence spectra of the white light LED prepared using gold cluster-copper cluster composite microspheres in Example 4 at different driving currents.

[0061] Figure 14 The following are photos and CIE chromaticity diagrams of white light LEDs prepared using gold cluster-copper cluster composite microspheres in Example 4. DETAILED DESCRIPTION

[0062] The present invention will be further described below with reference to specific embodiments and drawings, but is not limited thereto.

[0063] The raw materials used in the examples are all conventional chemical reagents, commercially available products, among which propylthiouracil, NaOH, Cu(NO3)2, and chloroauric acid were purchased from Sinopharm Chemical Reagent Co., Ltd. and used directly without treatment before use.

[0064] Example 1:

[0065] A long-lifetime, highly luminescent gold cluster-copper cluster composite microsphere, the preparation steps of which are as follows:

[0066] (1) Mix 4 mL of propylthiouracil suspension (c = 50 mmol / L) and 1 mL of HAuCl4 (c = 30 mmol / L) aqueous solution, shake vigorously, and let stand for 36 hours;

[0067] (2) Add 0.2 mL of NaOH solution (c = 2 mol / L) to the mixture after standing, shake vigorously, dilute the mixture to 10 mL with deionized water, and shake well to obtain a yellow transparent gold nanocluster solution;

[0068] (3) 5 mL of gold nanocluster solution was mixed with 0.6 mL of Cu(NO3)2 solution (c = 0.1 mol / L), shaken vigorously, and placed in a constant temperature incubator at 25°C for 36 h to obtain a suspension of gold cluster-copper cluster composite microspheres;

[0069] (4) After the suspension is centrifuged and dried under vacuum at room temperature, a solid powder of gold cluster-copper cluster composite microspheres is obtained.

[0070] like Figure 1 As shown, under a scanning electron microscope (SEM), the microstructure of the prepared gold cluster-copper cluster composite microspheres can be observed. The diameter of the composite microspheres is about 5 μm, and the composite microspheres are woven from nanowires with a diameter of 30 to 60 nm.

[0071] The valence states of Au and Cu in the prepared gold cluster-copper cluster composite microspheres were analyzed by X-ray photoelectron spectroscopy. Figure 2 and Figure 3 As shown, the valence states of Au and Cu are both zero and positive one.

[0072] like Figure 4 As shown in the figure, the prepared gold cluster-copper cluster composite microspheres were subjected to MALDI-TOF mass spectrometry analysis, in which the peaks at 952.93 and 1246.88 m / z correspond to Cu4(PRT)4Na + and Cu2Au3(PRT)3Na + , indicating that the microspheres are composed of a composite of gold clusters and copper clusters.

[0073] The fluorescence spectrum of the prepared gold cluster-copper cluster composite microspheres was tested. Figure 5 This is a steady-state fluorescence spectrum diagram, with an emission wavelength between 550 and 750 nm; the luminescence quantum yield is 28.78%; Figure 6 This is the time-resolved fluorescence decay curve, and its phosphorescence lifetime is 37.07 microseconds.

[0074] Example 2:

[0075] A long-lifetime, highly luminescent gold cluster-copper cluster composite microsphere, the preparation steps of which are as follows:

[0076] (1) Mix 4 mL of propylthiouracil suspension (c = 20 mmol / L) and 1 mL of HAuCl4 (c = 10 mmol / L) aqueous solution, shake vigorously, and let stand for 48 hours;

[0077] (2) Add 0.2 mL of NaOH solution (c = 1 mol / L) to the mixture after standing, shake vigorously, dilute the mixture to 10 mL with deionized water, and shake well to obtain a yellow transparent gold nanocluster solution;

[0078] (3) 5 mL of the gold nanocluster solution was mixed with 0.6 mL of a Cu(NO3)2 solution (c = 0.05 mol / L), shaken vigorously, and placed in a constant temperature incubator at 0°C for 48 h to obtain a suspension of gold cluster-copper cluster composite microspheres;

[0079] (4) After the suspension is centrifuged and dried under vacuum at room temperature, a solid powder of gold cluster-copper cluster composite microspheres is obtained.

[0080] like Figure 7 As shown, under a scanning electron microscope (SEM), the microstructure of the prepared gold cluster-copper cluster composite microspheres can be observed. The diameter of the composite microspheres is about 4 μm, and the composite microspheres are woven from nanowires with a diameter of 20 to 50 nm.

[0081] The fluorescence spectrum of the prepared gold cluster-copper cluster composite microspheres was tested. Figure 8 This is a steady-state fluorescence spectrum diagram, with an emission wavelength between 550 and 750 nm; the luminescence quantum yield is 23.62%; Figure 9 This is the time-resolved fluorescence decay curve, and its phosphorescence lifetime is 35.41 microseconds.

[0082] Example 3:

[0083] A long-lifetime, highly luminescent gold cluster-copper cluster composite microsphere, the preparation steps of which are as follows:

[0084] (1) Mix 4 mL of propylthiouracil suspension (c = 80 mmol / L) and 1 mL of HAuCl4 (c = 50 mmol / L) aqueous solution, shake vigorously, and let stand for 24 hours;

[0085] (2) Add 0.2 mL of NaOH solution (c = 5 mol / L) to the mixture after standing, shake vigorously, dilute the mixture to 10 mL with deionized water, and shake well to obtain a yellow transparent gold nanocluster solution;

[0086] (3) 5 mL of gold nanocluster solution was mixed with 0.6 mL of Cu(NO3)2 solution (c = 0.2 mol / L), shaken vigorously, and placed in a constant temperature incubator at 50°C for 24 h to obtain a suspension of gold cluster-copper cluster composite microspheres;

[0087] (4) After the suspension is centrifuged and dried under vacuum at room temperature, a solid powder of gold cluster-copper cluster composite microspheres is obtained.

[0088] like Figure 10 As shown, under a scanning electron microscope (SEM), the microstructure of the prepared gold cluster-copper cluster composite microspheres can be observed. The diameter of the composite microspheres is about 6 μm, and the composite microspheres are woven from nanowires with a diameter of 50 to 80 nm.

[0089] The fluorescence spectrum of the prepared gold cluster-copper cluster composite microspheres was tested. Figure 11 The steady-state fluorescence spectrum shows an emission wavelength between 550 and 750 nm. The quantum yield is 22.08%. Figure 12 This is the time-resolved fluorescence decay curve, and its phosphorescence lifetime is 30.85 microseconds.

[0090] Example 4:

[0091] The long-life, highly luminescent gold cluster-copper cluster composite microspheres prepared in Example 1 were applied to white light LEDs.

[0092] The solid powder of gold cluster-copper cluster composite microspheres prepared in Example 1 was mixed with commercially available BaMgAl 10 O 17 :Eu 2+ Phosphor and (Ba,Sr)2SiO4:Eu 2+ The phosphors were mixed in a mass ratio of 2:1.5:1 and coated on a 395nm near-ultraviolet GaN chip to produce an LED. The electroluminescence spectrum of the prepared LED at a driving current of 20 to 140 mA is shown in the figure below. Figure 13 As shown. Under the driving current of 140mA, the LED emits cool white light, as shown Figure 14 As shown, the color coordinates are (0.2884, 0.3604), the color rendering index is 81.9, and the correlated color temperature is 7433K.

Claims

1. A long-life, highly luminescent gold cluster-copper cluster composite microsphere, characterized in that: The composite microsphere is a spherical assembly formed by tightly weaving nanowires, wherein the nanowires are self-assembled from gold clusters and copper clusters; The core of the gold cluster is composed of zero-valent gold and positive monovalent gold, and the protective ligand is propylthiouracil; the core of the copper cluster is composed of zero-valent copper and positive monovalent copper, and the protective ligand is propylthiouracil; The diameter of the nanowire is 20-80 nm, and the diameter of the spherical assembly is 3-8 μm; The gold cluster-copper cluster composite microspheres have the following optical properties: phosphorescence emission wavelength is between 550 and 750 nm, luminescence lifetime is greater than 30 microseconds, and luminescence quantum yield is greater than 20%.

2. The long-life, highly luminescent gold cluster-copper cluster composite microsphere according to claim 1, characterized in that: The molar ratio of gold to propylthiouracil in the gold clusters is (0.03 - 0.6):

1.

3. The long-lifetime, highly luminescent gold cluster-copper cluster composite microsphere according to claim 1, characterized in that: The molar ratio of copper to propylthiouracil in the copper cluster is (0.2 - 3):

1.

4. The long-lifetime, highly luminescent gold cluster-copper cluster composite microsphere according to claim 1, characterized in that: In the gold cluster-copper cluster composite microspheres, the molar ratio of gold to copper is 1:(1.2 - 50).

5. The method for preparing the long-life, highly luminescent gold cluster-copper cluster composite microspheres according to any one of claims 1 to 4, comprising the following steps: (1) uniformly mixing an aqueous suspension of propylthiouracil and an aqueous solution of HAuCl4 and allowing the mixture to stand to obtain a mixed solution; (2) Adding NaOH solution to the mixed solution and mixing evenly to obtain a gold nanocluster solution; (3) Adding Cu(NO3)2 solution to the gold nanocluster solution, shaking and then standing at a constant temperature to obtain a suspension of gold cluster-copper cluster composite microspheres; (4) The suspension of the gold cluster-copper cluster composite microspheres is centrifuged and then vacuum dried to obtain a solid powder of the gold cluster-copper cluster composite microspheres.

6. The method for preparing long-life strong luminescent gold cluster-copper cluster composite microspheres according to claim 5, characterized in that: The concentration of the propylthiouracil suspension used in step (1) is 20 to 80 mmol / L, and the concentration of the HAuCl4 aqueous solution used is 10 to 50 mmol / L; the molar ratio of propylthiouracil to HAuCl4 is 1:(0.03 - 0.6).

7. The method for preparing long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres according to claim 5, characterized in that: In step (2), the concentration of the NaOH solution used is 1 to 5 mol / L.

8. The method for preparing long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres according to claim 5, characterized in that: In step (3), the concentration of the Cu(NO3)2 solution used is 0.05 ~ 0.2 mol / L, and the molar ratio of Cu(NO3)2 to HAuCl4 is (1.2 - 50):

1.

9. The method for preparing long-lifetime, highly luminescent gold cluster-copper cluster composite microspheres according to claim 5, wherein: The constant temperature in step (3) is 0 ~ 50 °C.

10. Use of the long-life, highly luminescent gold cluster-copper cluster composite microspheres according to any one of claims 1 to 4 in white light LEDs.

11. A white light LED comprising the long-life, highly luminescent gold cluster-copper cluster composite microspheres according to any one of claims 1 to 4.

12. The method for preparing a white light LED according to claim 11, comprising the following steps: The solid powder of gold cluster-copper cluster composite microspheres was mixed with BaMgAl 10 O 17 :Eu 2+ Phosphor and (Ba,Sr)2SiO4:Eu 2+ The phosphors are mixed and coated on a 395nm near-ultraviolet GaN chip to produce an LED.

Images