A preparation method of green fluorescent carbon-based quantum dots and its application in high color gamut display field

Abstract

A method for preparing green fluorescent carbon-based quantum dots and their application in high color gamut displays. A polybenzene ring powder precursor is nitrated with nitric acid and dried to obtain powder A. Powder A is then subjected to a solvothermal reaction and purified to obtain high-brightness green fluorescent carbon-based quantum dots. These green fluorescent carbon-based quantum dots are uniformly dispersed in a polymer substrate to prepare a high-brightness and high-stability green fluorescent carbon-based quantum dot composite film. A red fluorescent KSF:Mn... 4+ Phosphors are encapsulated within InGaN blue LED chips and then combined with the aforementioned green fluorescent carbon-based quantum dot composite film to prepare a composite device. The carbon-based quantum dots prepared in this invention have a size range of 2-6 nm. Their abundant surface functional groups allow them to be uniformly dispersed in various polymer substrates, exhibiting bright green fluorescence and demonstrating obvious excitation-independent emission characteristics. Their emission peak is between 510-525 nm, and their absolute quantum yield reaches over 90%.

Description

Technical Field

[0001] This invention relates to a method for preparing high-brightness green fluorescent carbon-based quantum dots, specifically to a method for preparing green fluorescent carbon-based quantum dots and their application in the field of high color gamut displays. Background Technology

[0002] Modern display technology, including liquid crystal displays (LCDs), relies on backlights for illumination. Traditional backlights include fluorescent lamps and white light-emitting diodes (WLEDs), but these light sources typically require additional optical components for color adjustment. WLED backlights are now widely used in LCD technology; commercially available WLED backlights typically employ blue InGaN chips (λ = 460nm) and narrow-band green-emitting β-SiAlON:Eu... 2+ (λ=540nm) and K2SiF6:Mn exhibiting red fluorescence emission 4+ (KSF:Mn 4+ (λ = 630 nm). Because the human eye is highly sensitive to green light, research on narrow-band green light emitting materials is crucial. Current research has extensively studied and developed a series of green light emitting materials, including CdSe / ZnS quantum dots, rare-earth-doped phosphors, and perovskite CsPbBr3 quantum dots. These materials have a full width at half maximum (FWHM) ≤ 50 nm and have become major research materials for LCDs. However, the toxicity issues associated with Cd-based quantum dots and sulfide instability limit the application of CdSe / ZnS quantum dots. The development of narrow-band green light emitting rare-earth-doped phosphors remains challenging, primarily due to the scarcity of rare-earth elements. Perovskite CsPbBr3 quantum dots, with an FWHM ≤ 25 nm, are considered promising narrow-band green light emitting materials for wide color gamut backlight displays. However, the commercial application of these quantum dots is limited by problems such as lead ion contamination, susceptibility to thermal decomposition, unstable quantum efficiency, and low thermal stability. Furthermore, current commercial phosphors have limitations in terms of FWHM, emission peak, and synthesis conditions, making them unsuitable for future wide color gamut display technologies. Therefore, there is an urgent need to develop a novel, rare-earth-free, highly thermally stable, and low-toxicity green fluorescent emitting material.

[0003] Carbon is a versatile element with excellent chemical stability, tolerating a wide range of chemical environments. Its monolayer graphitic carbon structure exhibits superior light transmittance, making it promising for applications in transparent electronics, liquid crystal displays, and solar cells. Carbon-based quantum dots, as an emerging luminescent material, offer advantages such as tunable spectral properties, widely available raw materials, simple preparation processes, and low cytotoxicity. Particularly significant progress has been made in the synthesis and design of carbon dots in the liquid state, resulting in high quantum efficiency, excellent optical stability, and multicolor emission characteristics. However, the luminescence of solid-state fluorescent carbon dots is affected by… The influence of resonance energy transfer and fluorescence quenching caused by direct π-π interactions in the aggregated state of fluorescent carbon dots. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing green fluorescent carbon-based quantum dots with broad application prospects in fields such as lighting and backlight displays, and their application in the field of high color gamut displays.

[0005] To achieve the above objectives, the present invention provides a method for preparing green fluorescent carbon-based quantum dots, comprising the following steps:

[0006] 1) Take the powder precursor with polybenzene ring characteristics and prepare a solution of 1-5 mg / mL with nitric acid, heat it at 60-100℃ for 12-36 h and then cool it to room temperature to obtain reaction solution A;

[0007] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 5-7, and dry to obtain powder B;

[0008] 3) The powder B was purified by solvothermal reaction to obtain high-brightness green fluorescent carbon-based quantum dots.

[0009] The multi-benzene ring characteristic powder precursors include naphthalene, anthracene, benzo[a]anthracene, pyrene, perylene, benzo[a]perylene, anthracene-anthracene, or 1,4-bis(1-pyrene)benzene.

[0010] The solvent used in the solvothermal reaction is one or a combination of methanol, ethanol, N,N-dimethylformamide, toluene, pentane, hexane, acetone, methyl ethyl ketone, ethylene glycol monobutyl ether, and pyridine, and the reaction temperature is 80-240℃.

[0011] The purification process employs one or more methods, including centrifugation, dialysis, and column chromatography.

[0012] The green fluorescent carbon-based quantum dots prepared by the above method have a particle size of 2-6 nm.

[0013] The carbon-based quantum dots formed are dispersed in a solvent and emit wavelengths of 510-525 nm, with a full width at half maximum (FWHM) of 50-90 nm and an absolute quantum yield of over 90%.

[0014] Green fluorescent carbon-based quantum dots and KSF:Mn prepared according to the above method were obtained. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0015] 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in a polymer substrate at a mass ratio of 0.1-1% to prepare a green fluorescent carbon-based quantum dot composite film with high brightness and high stability.

[0016] 2) Add red KSF:Mn 4+ Phosphor powder is mixed with LED organic potting compound at a mass ratio of 1-10% to obtain mixture A;

[0017] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0018] The polymer substrate is one of polyvinyl alcohol, polymethyl methacrylate, polystyrene, polydimethylsiloxane, polyimide, polyurethane, polyethylene glycol, polyvinylpyrrolidone, and polyvinyl butyral.

[0019] The green fluorescent carbon-based quantum dot composite film in step 1) is prepared by solution method or melt method;

[0020] The solution preparation method includes dissolving green fluorescent carbon-based quantum dots and a polymer substrate in a solvent, then casting the solution onto a plate, forming a film through solvent evaporation, or coating with a coating rod to form a green fluorescent carbon-based quantum dot composite film with a fixed thickness of 80-200 nm.

[0021] The melting method is as follows: polymer substrate particles are added to the sample chamber of a torque rheometer, the temperature is raised to 150-200℃, and after the polymer substrate particles are completely melted, green fluorescent carbon-based quantum dots are added. After stirring evenly at 10-30 rpm, the temperature is lowered to below 120℃ to obtain a carbon-based quantum dot / polymer substrate composite material. The green fluorescent carbon-based quantum dot composite film is obtained by hot pressing or high-temperature casting.

[0022] The fabricated composite device achieved a color gamut of over 100% NTSC in the CIE 1931 color space, with white point coordinates of (0.32±0.01, 0.33±0.01), a color temperature of around 5600K, and a luminous efficiency of over 280 Im / W.

[0023] The present invention has the following advantages:

[0024] 1. By optimizing experimental conditions and using a multi-benzene ring precursor, high-brightness and stable green fluorescent carbon-based quantum dots were prepared.

[0025] 2. The prepared carbon dots have abundant functional groups on their surface and can be dispersed in polymer substrates using various methods to prepare carbon-based quantum dot composite films with good dispersibility.

[0026] 3. The prepared carbon-based quantum dot composite film has good optical properties, anti-blue light bleaching properties, and insensitivity to temperature and humidity, and has potential for a variety of applications;

[0027] 4. Blue InGaN composite WLEDs devices encapsulated with carbon-based quantum dot composite films and red phosphors have high luminous efficiency and good stability, and have application potential in the fields of lighting and backlighting displays. Attached Figure Description

[0028] Figure 1 This is a transmission electron microscope image of the green fluorescent carbon-based quantum dots prepared in this invention.

[0029] Figure 2 Phase characterization of the green fluorescent carbon-based quantum dots prepared in this invention.

[0030] Figure 3 The optical properties of the green fluorescent carbon-based quantum dots prepared in this invention are characterized.

[0031] Figure 4 The optical properties and a series of aging results of the carbon-based quantum dot composite film prepared in this invention are characterized.

[0032] Figure 5 The full spectrum of the carbon-based quantum dot composite film prepared in this invention, combined with the blue InGaN and red phosphor composite film. Detailed Implementation

[0033] Example 1:

[0034] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0035] 1) Prepare a 1 mg / mL solution of pyrene powder precursor with nitric acid, heat at 60℃ for 12 h and then cool to room temperature to obtain reaction solution A;

[0036] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0037] 3) Place the above powder B in methanol and carry out a solvothermal reaction at 100°C. After the reaction is completed, high-brightness green fluorescent carbon-based quantum dots are obtained by dialysis.

[0038] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0039] 1) Green fluorescent carbon-based quantum dots are uniformly dispersed in polystyrene at a mass ratio of 0.5% using a melt method, and then a green fluorescent carbon-based quantum dot composite film is prepared by hot pressing or high-temperature casting.

[0040] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 3% to obtain mixture A;

[0041] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0042] The following explanation, in conjunction with the accompanying drawings, further illustrates the following:

[0043] Microstructure of carbon-based quantum dots

[0044] Figure 1 Transmission electron microscopy (TEM) images of carbon-based quantum dots synthesized in Example 1 are shown. As can be seen from the images, the samples are uniformly distributed, the sample quantity is large, the particle size is between 2-6 nm, and the average particle size is about 4 nm. The high-resolution TEM images show that the interplanar spacing is 0.21 nm, corresponding to the (100) crystal plane of graphite.

[0045] Figure 2 The phase structure characterization results of the carbon-based quantum dots synthesized in Example 1 are shown. Figure (a) shows the Raman spectrum, which reveals that the high-brightness green fluorescent carbon-based quantum dots exhibit a distinct disordered D-band (sp). 3 (structure) and crystal G-band (sp) 2 The structure shows a high peak intensity in the G band, indicating that the graphitic sp of the green fluorescent carbon-based quantum dots... 2 The structure is relatively good; Figure (b) shows the full X-ray photoelectron spectrum, indicating the presence of C, N, and O elements; Figure (c) is the high-resolution N1s spectrum, showing that the N1s spectrum can be fitted to pyrrole nitrogen (398.5 eV), graphitized nitrogen (400.5 eV), -NH2 (401.3 eV), and -NO2 (406.5 eV), thus the carbon-based quantum dot surface contains a large number of surface functional groups; Figure (d) is the infrared spectrum, showing that the carbon-based quantum dots have C=O (1700 cm⁻¹) energy. -1 C = N (1620cm) -1 ), CO (1080-1120cm) -1 ), CN (1250cm) -1 ), NH (3100-3650cm) -1) and CH(2875cm -1 The stretching vibration peak of the bond is consistent with the characterization results of X-ray photoelectron spectroscopy.

[0046] Optical properties of carbon-based quantum dots

[0047] Figure 3 The UV-Vis absorption, excitation, and fluorescence emission spectra of the carbon-based quantum dots synthesized in Example 1 are shown. The high-energy absorption band (<350 nm) in the UV-Vis absorption spectrum is caused by π-π* transitions between CN and CC bonds, while the specific absorption peak at 457 nm shows a large number of sp... 2 Bonded carbon. When excited with an excitation wavelength of 460 nm, the carbon-based quantum dot ethanol solution exhibits bright green fluorescence, showing obvious excitation-independent characteristics. The excitation wavelength is 365-480 nm, and the emission peak is 515 nm. The absolute quantum yield is as high as 90% or more.

[0048] Characterization of optical properties and stability of carbon-based quantum dot composite films

[0049] Figure 4 The optical properties and stability characterization results of the carbon-based quantum dot composite film synthesized in Example 1 are presented. (a) Different carbon-based quantum dot addition ratios: the fluorescence emission peak of the carbon-based quantum dot composite film with all three addition ratios is 515 nm. Further investigation of the thermal stability, resistance to blue light bleaching, and high-temperature and high-humidity aging performance of the carbon-based quantum dot composite film is conducted. (b) Temperature-dependent fluorescence performance of the carbon-based quantum dot composite film: at 90 °C, it still maintains 107% fluorescence intensity with slight fluorescence enhancement. (c) After treatment at 85 °C and 85% RH for 100 h, the carbon-based quantum dot composite film still maintains its initial fluorescence intensity and emission peak intensity, exhibiting good resistance to high-temperature and high-humidity aging. (d) Blue light aging of the carbon-based quantum dot composite film under a 3W blue light lamp at a distance of 5 cm: after 480 h of blue light aging, the fluorescence intensity of the composite film still remains above 95%, exhibiting good resistance to blue light bleaching. (e) Blue light aging of the carbon-based quantum dot composite film under blue light on InGaN… Blue light aging test was performed on the LED surface with a test current of 5mA. After 24 hours of blue light LED aging, the electroluminescence spectrum of the composite device was basically consistent with the test spectrum of the unaged device. (f) The brightness change of the composite device with carbon-based quantum dot composite film on the surface of blue InGaN LED. After 24 hours of blue light LED aging, its brightness was still above 95%.

[0050] Characterization of applications of carbon-based quantum dot composite films

[0051] Figure 5The electroluminescence spectra of the synthesized WLEDs in Example 1 are shown. Under a current of 5 mA, based on the fluorescence spectra of different bandpass filters, the prepared composite device achieved a color gamut of 107% NTSC in the CIE 1931 color space, with white point coordinates of (0.3299, 0.3322), a color temperature of Tc = 5692 K, and a luminous efficacy of 286.58 Im / W. This indicates that the carbon-based quantum dot composite film is an ideal composite film material suitable for backlight displays.

[0052] Example 2:

[0053] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0054] 1) Prepare a 2 mg / mL solution by mixing perylene powder precursor with nitric acid, heat at 70°C for 24 h and then cool to room temperature to obtain reaction solution A;

[0055] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0056] 3) Place the above powder B in ethanol and carry out a solvothermal reaction at 150°C. After the reaction is completed, obtain high-brightness green fluorescent carbon-based quantum dots by column chromatography and centrifugation.

[0057] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0058] 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in polymethyl methacrylate at a mass ratio of 1% by melt method, and green fluorescent carbon-based quantum dot composite film was prepared by hot pressing or high temperature casting.

[0059] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 5% to obtain mixture A;

[0060] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0061] Example 3:

[0062] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0063] 1) Prepare a 2 mg / mL solution by mixing anthracene powder precursor with nitric acid, heat at 80 °C for 36 h and then cool to room temperature to obtain reaction solution A;

[0064] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0065] 3) Place the above powder B in N,N-dimethylformamide and carry out a solvothermal reaction at 80°C. After the reaction is completed, high-brightness green fluorescent carbon-based quantum dots are obtained by dialysis and centrifugation.

[0066] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0067] 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in polyvinyl alcohol at a mass ratio of 0.3% by melt method, and a green fluorescent carbon-based quantum dot composite film was prepared by hot pressing or high temperature casting.

[0068] 2) Add red KSF:Mn 4+ Phosphor powder is mixed with LED organic potting compound at a mass ratio of 10% to obtain mixture A;

[0069] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0070] Example 4:

[0071] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0072] 1) Prepare a 3 mg / mL solution by mixing naphthalene powder precursor with nitric acid, heat at 100℃ for 16 h and then cool to room temperature to obtain reaction solution A;

[0073] 2) Wash the above reaction solution A with deionized water by centrifugation until the pH value is 5, and dry to obtain powder B;

[0074] 3) Place the above powder B in toluene and carry out a solvothermal reaction at 200°C. After the reaction is completed, obtain high-brightness green fluorescent carbon-based quantum dots by column chromatography.

[0075] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0076] 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in polydimethylsiloxane at a mass ratio of 0.8% using a melt method, and a green fluorescent carbon-based quantum dot composite film was prepared by hot pressing or high-temperature casting.

[0077] 2) Add red KSF:Mn 4+Phosphor powder was mixed with LED organic potting compound at a mass ratio of 1% to obtain mixture A;

[0078] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0079] Example 5:

[0080] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0081] 1) Prepare a 5 mg / mL solution of benzanthracene powder precursor with nitric acid, heat at 70 °C for 20 h and then cool to room temperature to obtain reaction solution A;

[0082] 2) Wash the above reaction solution A with deionized water by centrifugation until the pH value is 6, and dry to obtain powder B;

[0083] 3) Place the above powder B in pentane and carry out a solvothermal reaction at 240°C. After the reaction is completed, high-brightness green fluorescent carbon-based quantum dots are obtained by centrifugation.

[0084] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0085] 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in polyimide at a mass ratio of 0.6% using a melt method, and then a green fluorescent carbon-based quantum dot composite film was prepared by hot pressing or high-temperature casting.

[0086] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 4% to obtain mixture A;

[0087] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0088] Example 6:

[0089] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0090] 1) Prepare a 4 mg / mL solution of benzo[a]perylene powder precursor with nitric acid, heat at 80°C for 24 h and then cool to room temperature to obtain reaction solution A;

[0091] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0092] 3) Place the above powder B in acetone and carry out a solvothermal reaction at 120°C. After the reaction is completed, high-brightness green fluorescent carbon-based quantum dots are obtained by dialysis.

[0093] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0094] Green fluorescent carbon-based quantum dots are uniformly dispersed in polyurethane at a mass ratio of 0.1% using a solution method. The solution is then cast onto a plate, and a film is formed by solvent evaporation. Alternatively, a green fluorescent carbon-based quantum dot composite film with a fixed thickness of 80-200 nm with high brightness and high stability is formed by coating with a coating rod.

[0095] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 6% to obtain mixture A;

[0096] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0097] Example 7:

[0098] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0099] 1) Prepare a 2 mg / mL solution by mixing anthracene-anthracene powder precursor with nitric acid, heat at 60 °C for 28 h and then cool to room temperature to obtain reaction solution A;

[0100] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0101] 3) The powder B was placed in a mixed solution of methyl ethyl ketone and ethylene glycol monobutyl ether and subjected to a solvothermal reaction at 180°C. After the reaction was completed, high-brightness green fluorescent carbon-based quantum dots were obtained by column chromatography and centrifugation.

[0102] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0103] 1) Green fluorescent carbon-based quantum dots are uniformly dispersed in polyethylene glycol at a mass ratio of 0.7% using a solution method. The solution is then cast onto a plate, and a film is formed by the evaporation of the solvent. Alternatively, a green fluorescent carbon-based quantum dot composite film with a fixed thickness of 80-200 nm with high brightness and high stability can be formed by coating with a coating rod.

[0104] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 8% to obtain mixture A;

[0105] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

[0106] Example 8:

[0107] A method for preparing green fluorescent carbon-based quantum dots for high color gamut displays includes the following steps:

[0108] 1) Take 1,4-bis(1-pyrene)benzene powder precursor and prepare a 1 mg / mL solution with nitric acid. Heat at 90 °C for 32 h and then cool to room temperature to obtain reaction solution A;

[0109] 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 7, and dry to obtain powder B;

[0110] 3) Place the above powder B in pyridine and carry out a solvothermal reaction at 220°C. After the reaction is completed, high-brightness green fluorescent carbon-based quantum dots are obtained by dialysis and centrifugation.

[0111] The carbon-based quantum dot composite material and KSF:Mn prepared by the above method are shown in the image. 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor includes the following steps:

[0112] 1) Green fluorescent carbon-based quantum dots are uniformly dispersed in polyvinyl butyral at a mass ratio of 0.5% using a solution method. The solution is then cast onto a plate, and a film is formed by solvent evaporation, or a coating rod is used to coat the film to form a high-brightness and high-stability green fluorescent carbon-based quantum dot composite film with a fixed thickness of 80-200 nm.

[0113] 2) Add red KSF:Mn 4+ Phosphor powder was mixed with LED organic potting compound at a mass ratio of 9% to obtain mixture A;

[0114] 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

Claims

1. A method for preparing green fluorescent carbon-based quantum dots, characterized in that... Includes the following steps: 1) Take the powder precursor with polybenzene ring characteristics and prepare a solution of 1-5 mg / mL with nitric acid, heat it at 60-100℃ for 12-36 h and then cool it to room temperature to obtain reaction solution A; The multi-benzene ring characteristic powder precursors include naphthalene, anthracene, benzo[a]anthracene, pyrene, perylene, benzo[a]perylene, anthracene-anthracene, or 1,4-bis(1-pyrene)benzene; 2) Wash the above reaction solution A by centrifugation with deionized water until the pH value is 5-7, and dry to obtain powder B; 3) The powder B was purified by solvothermal reaction to obtain high-brightness green fluorescent carbon-based quantum dots; The solvent used in the solvothermal reaction is one or a combination of methanol, ethanol, N,N-dimethylformamide, toluene, pentane, hexane, acetone, methyl ethyl ketone, ethylene glycol monobutyl ether, and pyridine, and the reaction temperature is 80-240℃.

2. The method for preparing green fluorescent carbon-based quantum dots according to claim 1, characterized in that: The purification process employs one or more methods, including centrifugation, dialysis, and column chromatography.

3. The green fluorescent carbon-based quantum dots prepared by the method according to claim 1, characterized in that, The resulting carbon-based quantum dots have a particle size of 2-6 nm.

4. The green fluorescent carbon-based quantum dots prepared by the method according to claim 1, characterized in that, The carbon-based quantum dots formed are dispersed in a solvent and emit wavelengths of 510-525 nm, with a full width at half maximum (FWHM) of 50-90 nm and an absolute quantum yield of over 90%.

5. A green fluorescent carbon-based quantum dot and KSF:Mn prepared by the method described in claim 1 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor is characterized by: Includes the following steps: 1) Green fluorescent carbon-based quantum dots were uniformly dispersed in a polymer substrate at a mass ratio of 0.1-1% to prepare a high-brightness and high-stability green fluorescent carbon-based quantum dot composite film; 2) Add red KSF:Mn 4+ Phosphor powder is mixed with LED organic potting compound at a mass ratio of 1-10% to obtain mixture A; 3) The above mixture A is encapsulated in a blue light emitting InGaN chip and composited with a carbon-based quantum dot composite film to obtain composite devices WLEDs.

6. The green fluorescent carbon-based quantum dots and KSF:Mn according to claim 5 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor is characterized by: The polymer substrate is one of polyvinyl alcohol, polymethyl methacrylate, polystyrene, polydimethylsiloxane, polyimide, polyurethane, polyethylene glycol, polyvinylpyrrolidone, and polyvinyl butyral.

7. The green fluorescent carbon-based quantum dots and KSF:Mn according to claim 6 4+ The method for fabricating a blue InGaN composite device encapsulated with red phosphor is characterized by: The green fluorescent carbon-based quantum dot composite film in step 1) is prepared by solution method or melt method; The solution preparation method includes dissolving green fluorescent carbon-based quantum dots and a polymer substrate in a solvent, then casting the solution onto a plate, forming a film through solvent evaporation, or coating with a coating rod to form a green fluorescent carbon-based quantum dot composite film with a fixed thickness of 80-200 nm. The melting method is as follows: polymer substrate particles are added to the sample chamber of a torque rheometer, the temperature is raised to 150-200℃, and after the polymer substrate particles are completely melted, green fluorescent carbon-based quantum dots are added. After stirring evenly at 10-30 rpm, the temperature is lowered to below 120℃ to obtain a carbon-based quantum dot / polymer substrate composite material. The green fluorescent carbon-based quantum dot composite film is obtained by hot pressing or high-temperature casting.

8. The green fluorescent carbon-based quantum dot composite material and KSF:Mn prepared by the method according to claim 5 4+ A blue InGaN composite device encapsulated with red phosphor, characterized in that... The fabricated composite device achieved a color gamut of over 100% NTSC in the CIE 1931 color space, with white point coordinates of (0.32±0.01, 0.33±0.01), a color temperature of 5600K, and a luminous efficiency of over 280 lm / W.

Images