Orange light-emitting zinc oxide quantum dots with high fluorescence quantum yield and preparation method thereof

Abstract

This invention relates to an orange-light-emitting zinc oxide quantum dot based on high fluorescence quantum yield. It is synthesized in situ by adding a red fluorescent dye potassium hydroxide methanol mixture to an anhydrous methanol solution of zinc acetate and directly precipitating the particles at 62-64°C. The resulting zinc oxide composite nanomaterial has long-wavelength emission and high fluorescence quantum yield. It can be used as a phosphor in laser diodes to achieve white light emission, thus broadening the application of zinc oxide in optoelectronic devices.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device fabrication technology, and relates to luminescent materials for optoelectronic devices, particularly to a zinc oxide composite nanomaterial that can be used as a phosphor material in laser diodes, and a method for preparing the composite nanomaterial. Background Technology

[0002] Laser diodes (LDs), as a new generation of solid-state light sources, have advantages such as good monochromaticity, strong directionality, and high brightness, and do not suffer from "luminous efficacy degradation". They are suitable for some special lighting fields (such as laser car lights, projection displays, etc.) and are expected to replace ultra-high power light sources in high-brightness fields, achieving energy saving and environmental protection.

[0003] The implementation methods of white light LD devices are similar to those of white light emitting diodes (WLEDs), and can be divided into two main categories. The first category is to directly combine red, green and blue primary color laser light sources to obtain white light. The second category is the phosphor conversion method, which uses a monochromatic laser light source to excite phosphors, and the fluorescence emitted by the phosphors is mixed with the laser to obtain white light.

[0004] While the first type of method mentioned above has advantages such as high color rendering index and high lumen efficiency, the discrete multi-electrode emission system leads to increased costs and complex processes, which is not conducive to industrial production and practical use. The second type of method, on the other hand, achieves high-lumen illumination while also offering advantages such as low cost, simple process, and ease of control, making it a focus of research.

[0005] Currently, there are three types of phosphors used in laser lighting: rare earth-based phosphors, semiconductor quantum dot phosphors, and carbon quantum dot-based phosphors. Rare earth elements are non-renewable resources, scarce and facing depletion. Furthermore, their mining and purification often involve complex technologies and equipment, leading to increased mining costs and environmental pollution. The most commonly used semiconductor-based phosphor is cadmium-based semiconductor quantum dots, but the heavy metal cadmium poses potential health risks. Carbon quantum dot-based phosphors are a relatively new material developed in recent years. While they offer advantages such as low cost and tunable spectra, their relatively poor thermal and light stability limits their development.

[0006] Zinc oxide quantum dots (ZnO quantum dots) also possess excellent luminescent properties. Compared to cadmium-based quantum dots, they are non-toxic, harmless, and environmentally friendly because they do not contain heavy metal ions. Furthermore, compared to other semiconductor quantum dots, zinc oxide quantum dots are simpler to prepare, have lower production costs, and do not require complex steps or equipment. In addition, zinc oxide quantum dots have high luminescent efficiency, tunable emission color, good water solubility, and are easy to surface modify, making them a promising alternative to rare-earth phosphors and semiconductor cadmium-based phosphors.

[0007] However, due to the surface effect of zinc oxide, its high surface defect density easily leads to the aggregation and quenching of quantum dot particles. Moreover, its short emission wavelength limits its application in white light-emitting devices, resulting in the following defects as a semiconductor quantum dot:

[0008] 1. The photoluminescence quantum yield (PLQY) is relatively low;

[0009] 2. The low PLQY further limits its solid-state luminous efficiency;

[0010] 3. Since most zinc oxide markers emit short-wavelength light, it limits its use as a light-converting fluorescent material to be assembled with a 450nm blue LD to obtain white laser diodes (WLDs), thus limiting its application in laser lighting. Summary of the Invention

[0011] The purpose of this invention is to provide an orange-light zinc oxide quantum dot with high fluorescence quantum yield and its preparation method. By combining it with a red fluorescent dye, a zinc oxide composite nanomaterial with long-wavelength emission and high fluorescence quantum yield is obtained.

[0012] Providing the application of the orange-colored zinc oxide quantum dots as phosphors for laser diodes is another objective of this invention.

[0013] The core technology of this invention is to select a suitable red fluorescent dye and uniformly disperse it in zinc oxide to form an orange-fluorescent zinc oxide quantum dot composite nanomaterial with high fluorescence quantum yield. The specific approach to selecting the red fluorescent dye in this invention is as follows: 1) It can form chemical bonds with the surface of zinc oxide nanoparticles, that is, the red fluorescent dye molecules can react with hydroxyl groups and other groups on the surface of zinc oxide to form stable chemical bonds, ensuring the chemical stability of the composite nanomaterial; 2) It can achieve energy resonance transfer with zinc oxide nanoparticles, thereby improving its fluorescence quantum yield.

[0014] The orange-light zinc oxide quantum dots based on high fluorescence quantum yield described in this invention are composite nanomaterials obtained by in-situ synthesis, which involves adding a red fluorescent dye potassium hydroxide methanol mixture to an anhydrous methanol solution of zinc acetate and directly precipitating the particles at 62-64°C.

[0015] The orange-colored zinc oxide quantum dots prepared by this invention are composite nanomaterials formed by zinc oxide as a matrix, with red fluorescent dye coated and uniformly dispersed in zinc oxide.

[0016] The red fluorescent dye can be any organic dye that emits red fluorescence. The red fluorescent dye preferably used in this invention is any one of Rhodamine B, Erythrosin B, Neutral Red, and Basic Red 9.

[0017] Specifically, in the orange zinc oxide quantum dots based on high fluorescence quantum yield described in this invention, the mass ratio of red fluorescent dye to zinc oxide is preferably 0.05 to 1.3:1.

[0018] More specifically, the mass ratio of the red fluorescent dye to zinc oxide is preferably 0.05 to 0.5:1.

[0019] Furthermore, the present invention also provides a method for preparing orange zinc oxide quantum dots based on high fluorescence quantum yield, which involves dispersing red fluorescent dye and potassium hydroxide in anhydrous methanol to obtain a red fluorescent dye potassium hydroxide methanol mixture, adding it dropwise to an anhydrous methanol solution of zinc acetate heated to 62-64°C, maintaining the temperature to carry out an in-situ synthesis reaction, allowing the precipitate to precipitate out by standing, washing and drying to obtain zinc oxide quantum dot composite nanomaterials.

[0020] In the preparation method described in this invention, after the red fluorescent dye potassium hydroxide methanol mixture is added dropwise, a pink precipitate will be produced, and the temperature should be maintained for a reaction of not less than 3 hours.

[0021] More preferably, the reaction time is 3 to 4 hours, and the reaction process is carried out under stirring.

[0022] After the reaction is complete, the reaction product is cooled to room temperature and allowed to stand for at least 4 hours to allow the precipitate to precipitate and settle completely.

[0023] Preferably, the present invention employs ultrasonic treatment to ultrasonically disperse red fluorescent dye and potassium hydroxide in anhydrous methanol, thereby obtaining a methanol mixture of potassium hydroxide and red fluorescent dye.

[0024] The orange-light zinc oxide quantum dot material prepared by this invention has a high fluorescence quantum yield and can be used as a phosphor in laser diodes, thus broadening the application of zinc oxide in optoelectronic devices.

[0025] This invention prepares an orange-light zinc oxide quantum dot composite nanomaterial through in-situ synthesis, which has both long wavelength and high fluorescence quantum yield. When applied to laser diodes, it can ultimately achieve white light.

[0026] Performance characterization results show that, unlike the short emission wavelength of standard zinc oxide nanomaterials used as phosphors in laser diodes, which is not conducive to achieving white light, the high fluorescence quantum yield orange zinc oxide quantum dot phosphors prepared in this invention, when applied to laser diodes, are beneficial for achieving white light laser diodes.

[0027] The method for preparing high-fluorescence quantum yield orange zinc oxide quantum dot composite nanomaterials of the present invention is simple and efficient, and suitable for large-scale industrial applications. Attached Figure Description

[0028] Figure 1 These are TEM images of the R-ZnO composite nanomaterials and ZnO nanomaterials prepared in Example 3.

[0029] Figure 2 The images show the X-ray diffraction patterns of the R-ZnO composite nanomaterials and ZnO nanomaterials prepared in Examples 3 and 4.

[0030] Figure 3 The images show the TG curves of R-ZnO composite nanomaterials prepared in Examples 1-4, as well as ZnO nanomaterials and RhB.

[0031] Figure 4 The images show the UV-Vis absorption spectra of R-ZnO composite nanomaterials prepared in Examples 1-4, as well as ZnO nanomaterials and RhB.

[0032] Figure 5 The PL spectra of R-ZnO composite nanomaterials prepared in Examples 1-4, and ZnO nanomaterials and RhB in liquid state are shown.

[0033] Figure 6 The PL spectra of R-ZnO composite nanomaterials and ZnO nanomaterials prepared in Examples 1-4 are shown in solid state.

[0034] Figure 7 The fluorescence lifetime decay curves of R-ZnO composite nanomaterials and ZnO nanomaterials prepared in Examples 1-4 are shown.

[0035] Figure 8 These are the emission spectra of white laser diode devices prepared from R-ZnO composite nanomaterials with different doping amounts.

[0036] Figure 9 These are the CIE chromaticity coordinates of white laser diode devices prepared from R-ZnO composite nanomaterials with different doping amounts.

[0037] Figure 10 These are the CIE chromaticity coordinates for white laser diode devices made from ZnO composite nanomaterials with different red fluorescent materials. Implementation

[0038] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can better understand and utilize the present invention, and are not intended to limit the scope of protection of the present invention.

[0039] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments and comparative examples of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the art, which are very clear and distinct in the relevant application fields. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0040] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art. Example

[0041] Example 1

[0042] Weigh 0.0275g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0043] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0044] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0045] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-5 with a Rhodamine B content of 5 wt%.

[0046] Example 2

[0047] Weigh 0.055g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0048] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0049] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0050] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-10 with a Rhodamine B content of 10 wt%.

[0051] Example 3

[0052] Weigh 0.165g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0053] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0054] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0055] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-30 with a Rhodamine B content of 30 wt%.

[0056] Example 4

[0057] Weigh 0.275g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0058] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0059] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0060] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-50 with a Rhodamine B content of 50 wt%.

[0061] Example 5

[0062] Weigh 0.385g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0063] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0064] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0065] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-70 with a Rhodamine B content of 70 wt%.

[0066] Example 6

[0067] Weigh 0.475g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0068] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0069] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0070] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-90 with a Rhodamine B content of 90 wt%.

[0071] Example 7

[0072] Weigh 0.605 g of Rhodamine B and 0.74 g of potassium hydroxide, add them to 23 mL of anhydrous methanol, and sonicate for 10 min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0073] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0074] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0075] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-110 with a Rhodamine B content of 110 wt%.

[0076] Example 8

[0077] Weigh 0.715g of Rhodamine B and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a Rhodamine B potassium hydroxide methanol mixture.

[0078] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above Rhodamine B potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0079] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0080] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial R-ZnO-130 with a Rhodamine B content of 130 wt%.

[0081] Comparative Example 1

[0082] Weigh 0.74 g of potassium hydroxide and add it to 33 mL of anhydrous methanol. Disperse the solution by sonication for 10 min to obtain a potassium hydroxide methanol solution.

[0083] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above potassium hydroxide methanol solution dropwise at a uniform rate over 10min.

[0084] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0085] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain pure ZnO nanomaterials.

[0086] Figure 1 TEM images are provided for ZnO nanomaterials prepared in Comparative Example 1 and composite nanomaterial R-ZnO-30% prepared in Example 3, respectively. From... Figure 1As shown in (a), the ZnO nanomaterials are spherical with a particle size of 3.56 nm. Further characterization of their crystal structure using high-resolution TEM (HRTEM) images revealed distinct lattice fringes and an interplanar spacing of approximately 0.25 nm, corresponding to their (101) crystal plane. As shown in (b), the composite nanomaterial R-ZnO-30% is also spherical with a particle size of 3.25 nm and an interplanar spacing of 0.25 nm. These results clearly demonstrate that the introduction of Rhodamine B effectively reduces the grain size and promotes the formation of ZnO quantum dots.

[0087] Figure 2 X-ray diffraction patterns of ZnO nanomaterials prepared in Comparative Example 1 and R-ZnO composite nanomaterials prepared in Examples 3 and 4 are shown. All samples in the figures exhibit the standard diffraction peaks of ZnO, with distinct diffraction peaks appearing at 2θ values ​​of 31°, 35°, 47°, 56°, 62°, and 67°, corresponding to the (100), (002), (101), (102), (110), and (103) crystal planes of hexagonal zinc fibrous ZnO, respectively. It can be seen that after introducing RhB, the diffraction peaks of the R-ZnO composite nanomaterials are basically consistent with those of ZnO, which means that introducing RhB to synthesize R-ZnO composite nanomaterials does not change the crystal structure of ZnO.

[0088] Figure 3 The thermogravimetric analysis (TG) curves of ZnO nanomaterials prepared in Comparative Example 1 and R-ZnO composite nanomaterials prepared in Examples 1-4 are presented. The weight of all materials decreased with increasing temperature. The thermogravimetric curves are divided into two regions. The first weight loss occurs at 100℃, which is related to the desorption of water molecules adsorbed on ZnO and R-ZnO and impurities. It can be seen that RhB begins to decompose at 250℃, with a final weight loss rate of 18.88%; the corresponding decomposition start temperature of R-ZnO is also 250℃, proving that the weight loss is mainly caused by the decomposition of RhB in the composite. The final weight loss rate of ZnO is 10.62%; while the final weight loss rates of R-ZnO-5%, R-ZnO-10%, R-ZnO-30%, and R-ZnO-50% are 8.97%, 13.07%, 10.64%, and 12.48%, respectively. R-ZnO exhibits a higher weight loss rate than ZnO, mainly attributed to the decomposition of RhB contained within its bulk, further confirming the presence of RhB. Overall, even when heated to 800℃, RhB and R-ZnO do not completely decompose, demonstrating extremely high thermal stability.

[0089] Figure 4The figures show the UV-Vis absorption spectra of ZnO nanomaterials prepared in Comparative Example 1 and R-ZnO composite nanomaterials prepared in Examples 1-4. In the figures, the undoped pure ZnO nanomaterials exhibit a prominent absorption peak at 325 nm, corresponding to the electronic transition from the valence band to the conduction band (O2P-Zn3d), with an absorption cutoff edge of 350 nm. The absorption cutoff edge of the R-ZnO composite nanomaterials with different RhB doping levels shows a slight red shift (approximately 360 nm) with increasing doping concentration, and a new absorption peak appears in the 450–580 nm range, corresponding to the characteristic absorption peak of RhB in methanol solution, demonstrating the presence of RhB molecules in the composite nanomaterials.

[0090] Figure 5 and Figure 6 Fluorescence spectra of ZnO nanomaterials prepared in Comparative Example 1 and R-ZnO composite nanomaterials prepared in Examples 1-4 are presented in solution and powder states, respectively.

[0091] from Figure 5 As can be clearly seen in (a), pure ZnO exhibits excitation independence in solution, with 360 nm being its optimal excitation wavelength, and the emission peak positions are all located at 517 nm. From the PL spectra (b-e) of liquid R-ZnO composite nanomaterials with different Rhodamine B doping amounts, it can be seen that after the introduction of Rhodamine B, the PL spectrum of R-ZnO undergoes a significant red shift, with the optimal emission peaks at 563, 570, 578, and 585 nm, respectively. The peak wavelength of the nanocomposite material shows a red shift (563-585 nm), exhibiting excitation-independent properties in the visible light region.

[0092] Figure 6 In (a), solid-state ZnO also exhibits excitation independence, with an optimal excitation wavelength of 365 nm and emission peaks at 541 nm. The photoluminescence (PL) spectra (b–e) of solid-state R-ZnO composite nanomaterials with different Rhodamine B doping concentrations also show a significant redshift, with optimal emission peaks at 544, 568, 569, and 577 nm, respectively, demonstrating excitation independence. These changes in PL after composite formation provide direct evidence of the presence of dye molecules within the ZnO matrix.

[0093] Figure 7 Fluorescence decay curves of ZnO nanomaterials prepared in Comparative Example 1 and R-ZnO composite nanomaterials prepared in Examples 1-4 are presented. From the fluorescence decay curves of R-ZnO composite nanomaterials with different Rhodamine B doping amounts, their fluorescence lifetimes are 1073.79, 3.27, 3.71, 3.64, and 3.14 ns, respectively. Compared with pure ZnO nanomaterials, the fluorescence lifetime of R-ZnO composite nanomaterials decreases significantly, indicating that charge transfer occurs between ZnO and Rhodamine B.

[0094] The quantum yields of ZnO and R-ZnO composite nanomaterials with different doping amounts were tested using an Edinburgh Spectrofluorometer FS5 fluorescence spectrometer. The test results are listed in Table 1.

[0095]

[0096] The QY of liquid pure ZnO was 7.12%, while the QY of R-ZnO was significantly improved after the introduction of Rhodamine B, with the highest QY of R-ZnO-30% reaching 85.21%. The QY of solid pure ZnO was 5.28%, and the QY was also significantly improved after the introduction of Rhodamine B, with the QY of solid R-ZnO-10% reaching as high as 30.25%. This result is directly related to the fluorescence resonance energy transfer (FRET) of RhB from ZnO to R-ZnO.

[0097] Example 9

[0098] Weigh 0.055g of sodium tetraiodofluorescein and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a sodium tetraiodofluorescein, potassium hydroxide and methanol mixture.

[0099] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above-mentioned tetraiodofluorescein sodium salt potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0100] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0101] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial E-ZnO-10 with a sodium tetraiodofluorescein content of 10 wt%.

[0102] Example 10

[0103] Weigh 0.165g of sodium tetraiodofluorescein and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a sodium tetraiodofluorescein, potassium hydroxide and methanol mixture.

[0104] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above-mentioned tetraiodofluorescein sodium salt potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0105] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0106] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial E-ZnO-30 with a sodium tetraiodofluorescein content of 30wt%.

[0107] Example 11

[0108] Weigh 0.055g of neutral red and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a neutral red potassium hydroxide methanol mixture.

[0109] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above neutral red potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0110] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0111] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain N-ZnO-10 composite nanomaterials with a neutral red content of 10 wt%.

[0112] Example 12

[0113] Weigh 0.165g of neutral red and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a neutral red potassium hydroxide methanol mixture.

[0114] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above neutral red potassium hydroxide methanol mixture dropwise at a uniform rate over 10min.

[0115] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0116] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain N-ZnO-30 composite nanomaterial with a neutral red content of 30 wt%.

[0117] Example 13

[0118] Weigh 0.055g of paraflavonoid hydrochloride and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a mixture of paraflavonoid hydrochloride, potassium hydroxide, and methanol.

[0119] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above-mentioned hydrochloric acid, paraflavonoid, potassium hydroxide, and methanol mixture dropwise at a uniform rate over 10min.

[0120] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0121] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial B-ZnO-10 with a hydrochloric acid para-red content of 10 wt%.

[0122] Example 14

[0123] Weigh 0.165g of parafrine hydrochloride and 0.74g of potassium hydroxide, add them to 23mL of anhydrous methanol, and sonicate for 10min to obtain a mixture of parafrine hydrochloride, potassium hydroxide, and methanol.

[0124] Weigh 1.475g of zinc acetate and add it to 63mL of anhydrous methanol. Heat the mixture to 62℃ with stirring and maintain the temperature. Add the above-mentioned hydrochloric acid, paraflavonoid, potassium hydroxide, and methanol mixture dropwise at a uniform rate over 10min.

[0125] After the addition is complete, maintain the temperature and continue stirring for 4 hours. Then stop heating and stirring and let stand for 4 hours to allow the product to settle completely.

[0126] The supernatant was discarded, and the product was washed twice with anhydrous methanol and centrifuged to obtain the composite nanomaterial B-ZnO-30 with a hydrochloric acid para-red content of 30 wt%.

[0127] The quantum yields of ZnO and R-ZnO composite nanomaterials with different doping amounts were tested using an Edinburgh Spectrofluorometer FS5 fluorescence spectrometer. The test results are listed in Table 1.

[0128] Table 2 further provides the statistical results of quantum yield in liquid and solid states for ZnO composite nanomaterials with different red fluorescent dyes doped with 10%. Compared with the QY value of 7.12% for liquid pure ZnO, the QY value was significantly improved after introducing different red fluorescent materials. Similarly, compared with the QY value of 5.28% for solid pure ZnO, the QY value was also improved after introducing different red fluorescent dyes.

[0129]

[0130] Application Example 1

[0131] The ZnO nanomaterials, R-ZnO-5% composite nanomaterials, R-ZnO-10% composite nanomaterials, R-ZnO-30% composite nanomaterials, and R-ZnO-50% composite nanomaterials prepared in this invention were used as phosphors, respectively, and were flatly placed between two 15mm diameter sapphire glass plates to form a solid-state fluorescent film. These films were then assembled with a 450nm blue LD to obtain white light laser diode (WLD) devices, and the device performance of each device was tested.

[0132] Figure 8 and Figure 9 The emission spectra and CIE chromaticity coordinates at 5.6V for different WLDs are given, and the specific device performance of each device is listed in Table 3.

[0133]

[0134] Among them, the WLD based on R-ZnO-10% phosphor was tested, with CIE coordinates of (0.33, 0.33), CCT of 5237K and CRI of 73. Compared with other recent reports on ZnO in light-emitting diodes, this shows the application potential of ZnO as a phosphor in the field of laser lighting.

[0135] Application Example 2

[0136] The E-ZnO-10% composite nanomaterials prepared in Example 9, the N-ZnO-10% composite nanomaterials prepared in Example 11, and the B-ZnO-10% composite nanomaterials prepared in Example 13 were used as phosphors. These were flattened between two 15mm diameter sapphire glass plates and encapsulated to form solid-state fluorescent films. These films were then assembled with a 450nm blue LD to obtain WLD devices. The device performance of each device was tested, and the specific results are listed in Table 4. These results are compared with the ZnO nanomaterials and R-ZnO-10% composite nanomaterials in Application Example 1. The CIE chromaticity coordinates are shown below. Figure 10 As shown.

[0137]

[0138] As shown in Table 4, white light emission was achieved with CIE coordinates (0.44, 0.54), CCT of 7586K, and CRI of 54 using a laser diode based on N-ZnO-10wt%.

[0139] The above embodiments of the present invention do not describe all details exhaustively, nor do they limit the present invention to the embodiments described above. Various changes, modifications, substitutions, and variations made by those skilled in the art to these embodiments without departing from the principles and spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. An orange light-emitting zinc oxide quantum dot, characterized by A composite nanomaterial was obtained by in-situ synthesis, in which a red fluorescent dye potassium hydroxide methanol mixture was added to an anhydrous methanol solution of zinc acetate and the mixture was directly precipitated at 62-64℃. The composite nanomaterial was formed with zinc oxide as the matrix and the red fluorescent dye coated and uniformly dispersed in the zinc oxide. The red fluorescent dye was any one of Rhodamine B, sodium tetraiodofluorescein, neutral red, or parafrine hydrochloride.

2. The orange light-emitting ZnO quantum dots according to claim 1, characterized in that The mass ratio of red fluorescent dye to zinc oxide is 0.05 to 1.3:

1.

3. The orange-colored zinc oxide quantum dots according to claim 1, characterized in that... The mass ratio of red fluorescent dye to zinc oxide is 0.05 to 0.5:

1.

4. The method for preparing orange light emitting zinc oxide quantum dots according to any one of claims 1 to 3, characterized in that A red fluorescent dye and potassium hydroxide were dispersed in anhydrous methanol to obtain a red fluorescent dye-potassium hydroxide-methanol mixture. This mixture was then added dropwise to an anhydrous methanol solution of zinc acetate heated to 62–64 °C. The temperature was maintained to carry out an in-situ synthesis reaction. After standing, a precipitate was formed, washed, and dried to obtain zinc oxide quantum dot composite nanomaterials.

5. The preparation method according to claim 4, characterized in that: The in-situ synthesis reaction time shall not be less than 3 hours.

6. The method of claim 5, wherein The in-situ synthesis reaction takes 3 to 4 hours and is carried out under stirring.

7. The method of claim 4 wherein The time for allowing the precipitate to stand and precipitate out shall not be less than 4 hours.

8. The method of claim 4 wherein A methanol mixture of potassium hydroxide and red fluorescent dye was prepared by ultrasonic dispersion of red fluorescent dye and potassium hydroxide in anhydrous methanol.

9. The application of the orange-colored zinc oxide quantum dots of claim 1 as phosphors for laser diodes.

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