CN113930240B - Fluorescent carbon quantum dot, preparation method thereof and warm white light emitting LED - Google Patents
Fluorescent carbon quantum dot, preparation method thereof and warm white light emitting LED Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 238000002360 preparation method Methods 0.000 title claims abstract description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 51
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000003093 cationic surfactant Substances 0.000 claims abstract description 28
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 19
- 230000005284 excitation Effects 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims abstract description 12
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 239000006228 supernatant Substances 0.000 claims abstract description 10
- 239000003960 organic solvent Substances 0.000 claims abstract description 7
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- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid group Chemical group C(CC(O)(C(=O)O)CC(=O)O)(=O)O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 60
- ZHNUHDYFZUAESO-UHFFFAOYSA-N Formamide Chemical group NC=O ZHNUHDYFZUAESO-UHFFFAOYSA-N 0.000 claims description 34
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 28
- QBVXKDJEZKEASM-UHFFFAOYSA-M tetraoctylammonium bromide Chemical group [Br-].CCCCCCCC[N+](CCCCCCCC)(CCCCCCCC)CCCCCCCC QBVXKDJEZKEASM-UHFFFAOYSA-M 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 10
- 238000004440 column chromatography Methods 0.000 claims description 8
- 238000000746 purification Methods 0.000 claims description 4
- SYZCZDCAEVUSPM-UHFFFAOYSA-M tetrahexylazanium;bromide Chemical compound [Br-].CCCCCC[N+](CCCCCC)(CCCCCC)CCCCCC SYZCZDCAEVUSPM-UHFFFAOYSA-M 0.000 claims description 4
- 238000004729 solvothermal method Methods 0.000 claims 4
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000001027 hydrothermal synthesis Methods 0.000 abstract description 10
- SWLVFNYSXGMGBS-UHFFFAOYSA-N ammonium bromide Chemical compound [NH4+].[Br-] SWLVFNYSXGMGBS-UHFFFAOYSA-N 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 3
- 231100000252 nontoxic Toxicity 0.000 abstract description 2
- 230000003000 nontoxic effect Effects 0.000 abstract description 2
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 21
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 238000001228 spectrum Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 239000011324 bead Substances 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 8
- XRWMGCFJVKDVMD-UHFFFAOYSA-M didodecyl(dimethyl)azanium;bromide Chemical compound [Br-].CCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCC XRWMGCFJVKDVMD-UHFFFAOYSA-M 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000002161 passivation Methods 0.000 description 6
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- 238000009877 rendering Methods 0.000 description 6
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- 230000002776 aggregation Effects 0.000 description 5
- 238000004220 aggregation Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 238000005286 illumination Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000002096 quantum dot Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- PUBAEMCRUKEVMY-UHFFFAOYSA-N benzhydryl(dimethyl)azanium;bromide Chemical compound [Br-].C=1C=CC=CC=1C([NH+](C)C)C1=CC=CC=C1 PUBAEMCRUKEVMY-UHFFFAOYSA-N 0.000 description 2
- 125000002091 cationic group Chemical group 0.000 description 2
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- 230000007704 transition Effects 0.000 description 2
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 description 1
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 1
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
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- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- 238000002189 fluorescence spectrum Methods 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
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- 239000000047 product Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- -1 rare earth ions Chemical class 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000009103 reabsorption Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- GNMJFQWRASXXMS-UHFFFAOYSA-M trimethyl(phenyl)azanium;bromide Chemical compound [Br-].C[N+](C)(C)C1=CC=CC=C1 GNMJFQWRASXXMS-UHFFFAOYSA-M 0.000 description 1
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/65—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
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- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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- H01L33/502—Wavelength conversion materials
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract
The invention belongs to the technical field of fluorescent materials, and particularly discloses a fluorescent carbon quantum dot, a preparation method thereof and a warm white light emitting LED. The raw material components for preparing the fluorescent carbon quantum dots comprise a carbon source, a nitrogen source and a cationic surfactant, wherein the cationic surfactant comprises ammonium bromide salt; the preparation method of the fluorescent carbon quantum dot comprises the following steps: adding a carbon source and a nitrogen source into an organic solvent, performing hydrothermal synthesis, filtering, and centrifuging to obtain a carbon dot solution; adding the carbon dot solution into the cationic surfactant, mixing, taking supernatant, and purifying to obtain the fluorescent carbon quantum dot. The fluorescent carbon quantum dot provided by the invention has the advantages that the preparation process is simple, the raw materials are nontoxic, the price is low, the photon stability and the thermal stability are good, warm white light emission can be generated under the excitation of blue light, the light efficiency can reach 70.21lm/w, the damage of blue light leakage caused by the excitation of the blue light can be avoided, and the fluorescent carbon quantum dot is suitable for being made into healthy warm white light emission LEDs.
Description
Technical Field
The invention belongs to the technical field of fluorescent materials, and particularly relates to a fluorescent carbon quantum dot, a preparation method thereof and a warm white light emitting LED.
Background
The white light LED has the advantages of high luminous efficiency, long service life, high response speed, high safety, low energy consumption and the like, and plays an important role in the fields of illumination and display.
At present, in white light LED research, a blue light chip is added with yellow fluorescent powder to generate cold white light emission, but due to the lack of red light components, the color rendering index is lower, and the danger of 'blue light leakage' is easy to occur, so that the application of the commercial white light LED is limited from the aspect of healthy illumination. The white light LED is prepared by adopting three LEDs of red, green and blue, and the color rendering index is generally higher, because the added red light part can remarkably broaden the light emitting spectrum of the LED, so that the LED meets the light emitting spectrum of sunlight as much as possible, namely, covers all visible light segments, thereby improving the color rendering index. At present, red fluorescent powder is generally synthesized by a matrix material (aluminate, silicate and tungstate) and rare earth ions (europium, thulium, holmium, erbium, samarium and yttrium), or red light is generated or enhanced in a co-doping mode, and a high-temperature solid phase method is generally adopted, and the method needs high-temperature calcination, so that the preparation condition is complex and the energy consumption is high. The traditional method for preparing the fluorescent quantum dots is used for preparing the cadmium selenide, cadmium telluride, cadmium sulfide and other quantum dots, so that the preparation cost is relatively high, the fluorescent quantum dots have toxicity, and the living idea of environment-friendly healthy illumination is not met.
Therefore, development of a fluorescent material which is low in cost, high in light efficiency and capable of emitting warm white light under blue light excitation is needed.
Disclosure of Invention
The invention provides a fluorescent carbon quantum dot, a preparation method thereof and a warm white light emitting LED (light emitting diode) so as to solve one or more technical problems in the prior art and at least provide a beneficial selection or creation condition.
To overcome the above technical problems, a first aspect of the present invention provides a fluorescent carbon quantum dot.
Specifically, the raw material components for preparing the fluorescent carbon quantum dot comprise a carbon source, a nitrogen source and a cationic surfactant, wherein the cationic surfactant comprises ammonium bromide salt.
The main preparation raw materials of the fluorescent carbon quantum dot comprise a carbon source, a nitrogen source and a cationic surfactant, wherein the carbon source and the nitrogen source are used for synthesizing the carbon dot, and the cationic surfactant is used as a passivating agent for passivating the surface defect of the carbon dot, so that the fluorescent carbon quantum dot capable of emitting yellow light is prepared, the quantum efficiency of the carbon dot can be remarkably improved, and the high light efficiency characteristic of an LED is shown. Meanwhile, the fluorescent carbon quantum dots emitted by yellow light have concentration aggregation-induced red shift effect, so that the fluorescent carbon quantum dots emitted by yellow light can be subjected to red shift in a solution with the concentration of 7-28mg/mL to form a red light emission center, and the warm white light characteristic of the LED is shown. Under the excitation of the blue light chip, not only a yellow light emission center exists, but also a red light emission center formed by concentration aggregation exists, so that warm white light emission is formed.
Preferably, the carbon source comprises citric acid.
Preferably, the nitrogen source comprises formamide.
As a further improvement of the above, the ammonium bromide salt is at least one selected from the group consisting of tetraoctylammonium bromide, tetrahexylammonium bromide, phenyltrimethylammonium bromide, didodecyl dimethyl ammonium bromide, and hexadecyl trimethylammonium bromide.
Preferably, the ammonium bromide salt is selected from the group consisting of tetraoctylammonium bromide and didodecyldimethylammonium bromide. Specifically, the ammonium bromide salts have proper chain length, which is beneficial to exerting the optimal quantum efficiency of the carbon quantum dots; when the cationic surfactant chain is short, the distance between carbon points is too short, non-radiative transitions are generated, and quantum efficiency is reduced; when the cationic surfactant chain is longer, electron-hole radiative recombination is reduced, which also reduces the quantum efficiency of the carbon dot.
As a further improvement of the above-mentioned scheme, the volume ratio of the mass of the carbon source to the nitrogen source is (1-3) g: (5-15) mL.
The second aspect of the invention provides a preparation method of fluorescent carbon quantum dots.
Specifically, the preparation method of the fluorescent carbon quantum dot comprises the following steps:
(1) Adding a carbon source and a nitrogen source into an organic solvent, performing hydrothermal synthesis, filtering, and centrifuging to obtain a carbon dot solution;
(2) And (3) adding the carbon dot solution prepared in the step (1) into a cationic surfactant, mixing, taking supernatant, and purifying to obtain the fluorescent carbon quantum dot.
In the step (1), citric acid is used as a carbon source, formamide is used as a nitrogen source, the citric acid and the formamide are subjected to hydro-thermal synthesis in a solvent, and dehydration reaction and cyclization reaction are carried out to generate luminescent carbon quantum dots; filtering and centrifuging to remove residual impurities and improve the purity of the luminescent carbon quantum dots.
In the step (2), the surface defects of the carbon dots are passivated by adopting a cationic surfactant so as to improve the quantum efficiency of the carbon dots and enable the carbon dots to have high light efficiency characteristics; because the bottom layer of the solution is possibly still containing a small amount of impurities after layering, the supernatant is taken for purification, and the fluorescent carbon quantum dot with better light efficiency characteristic is prepared.
Preferably, the organic solvent is selected from ethanol.
As a further improvement of the above scheme, in the step (1), the temperature of the hydrothermal synthesis is 140-200; the hydrothermal synthesis time is 6-8 hours.
As a further improvement of the above scheme, in step (2), the volume ratio of the mass of the cationic surfactant to the carbon dot solution is (0.1-1) g: (5-15) mL.
Preferably, in step (2), the purification is performed by column chromatography.
Further, methanol and methylene dichloride are adopted as developing agents for column chromatography purification, and the volume ratio of the methanol to the methylene dichloride is 1:1.
Preferably, the preparation method of the fluorescent carbon quantum dot comprises the following steps:
(1) Taking 1-3g of citric acid as a carbon source and 5-15mL of formamide as a nitrogen source, adding into 10-20mL of ethanol solution, stirring for 20-40 minutes, putting into a reaction kettle, performing hydrothermal synthesis at 140-200 ℃ for 6-8 hours, filtering, and centrifuging to obtain a carbon dot solution;
(2) Taking 5-10mL of the carbon dot solution prepared in the step (1), adding 0.1-1g of cationic surfactant, stirring for 20-40 minutes, taking the orange-yellow luminous carbon dot of the supernatant, and purifying by a column chromatography, wherein the volume ratio is 1:1, methanol and methylene dichloride are used as developing agents, and the fluorescent carbon quantum dots are obtained.
The third aspect of the invention provides an application of the fluorescent carbon quantum dot.
Specifically, in the application of the fluorescent carbon quantum dot, after the fluorescent carbon quantum dot is cured, the fluorescent carbon quantum dot is coated on the surface of a blue light chip, and the carbon quantum dot forms warm white light under the excitation of blue light.
Preferably, the emission wavelength of the blue light chip is 450-470nm.
As a further improvement of the above scheme, firstly, adding the fluorescent carbon quantum dots into an ethanol solution to prepare a fluorescent carbon quantum dot solution with a certain concentration, and dispersing the solution to uniformly disperse the fluorescent carbon quantum dots in the ethanol solution; then adding mesoporous silica into the fluorescent carbon quantum dot solution to load the mesoporous silica into a pore structure of the mesoporous silica, and curing to obtain fluorescent carbon quantum dot powder; and finally, coating fluorescent carbon quantum dot powder on a blue light chip, wherein the carbon quantum dots form warm white light under the excitation of blue light.
Preferably, the mass volume concentration of the fluorescent carbon quantum dots dispersed in the ethanol solution is 7-28mg/mL.
Specifically, fluorescent carbon quantum dots with a certain concentration can be aggregated to form a red light emission center, when the concentration is too low, a new red light emission center cannot be induced to be generated, and only cold white light can be emitted under the excitation of a blue light chip, but warm white light cannot be obtained; when the concentration is too high, the fluorescent carbon quantum dots are easy to quench in the curing process, so that the luminous efficacy of the carbon dots is reduced.
A fourth aspect of the invention provides another use of a fluorescent carbon quantum dot.
Specifically, an LED includes the fluorescent carbon quantum dot described above. The concentration of the fluorescent carbon quantum dots in the curing process is controlled, so that the fluorescent carbon quantum dots induce a red shift effect under the concentration aggregation effect to form a red light emission center, and the light-emitting device emits warm white light.
Compared with the prior art, the technical scheme of the invention has at least the following technical effects or advantages:
According to the invention, the cationic surfactant is used as a passivating agent to passivate the surface defects of the carbon dots, so that the fluorescent carbon quantum dot capable of emitting single-component yellow light with the carbon dot base is prepared, the quantum efficiency of the carbon dots can be remarkably improved, and the high light efficiency characteristic of the LED is shown. Meanwhile, the fluorescent carbon quantum dots emitted by the yellow light have a concentration aggregation induced red shift effect, and red light emission centers are induced to be generated by adjusting the concentration of the fluorescent carbon quantum dots, so that the defect of the red light emission centers in cold white light formed by the blue light chip and the carbon quantum dots emitted by the yellow light is overcome, and a warm white light LED with high color rendering index, high light efficiency and low color temperature is formed.
The fluorescent carbon quantum dot provided by the invention has the advantages that the preparation process is simple, the raw materials are nontoxic, the cost is low, the photon stability and the thermal stability are good, warm white light emission can be generated under the excitation of a blue light chip, the light efficiency can reach 70.21lm/w, the damage of blue light leakage caused by blue light excitation is avoided, meanwhile, the fluorescent carbon quantum dot can be used as clean energy to be applied to the field of illumination, and the fluorescent carbon quantum dot is suitable for being made into healthy warm white light emission LEDs.
Drawings
FIG. 1 is a 3D spectrum of fluorescent carbon quantum dots of different concentrations;
FIG. 2 is a graph of emission spectra of fluorescent carbon quantum dots of different concentrations;
FIG. 3 is a graph showing the comparison of emission intensity of fluorescent carbon quantum dots with different concentrations;
Fig. 4 is a pearlescent spectrum of the LED lamp of example 1;
FIG. 5 is a CIE coordinate diagram of example 1;
FIG. 6 is a physical view of a lamp bead of example 1;
FIG. 7 is a CIE coordinate diagram of comparative example 1;
FIG. 8 is a physical view of the lamp beads of comparative example 1;
FIG. 9 is a graph comparing the effect of different cationic surfactants passivation versus non-passivation on fluorescent carbon quantum dots.
Detailed Description
The present invention is specifically described below by way of examples to facilitate the understanding of the present invention by those skilled in the art, and it is necessary to specifically point out that the examples are provided for further illustration only and are not to be construed as limiting the scope of the present invention, and that insubstantial modifications and adjustments of the present invention according to the above teachings should still fall within the scope of the present invention, and that the raw materials mentioned below are not specifically described, but are commercially available products, and that the process steps or preparation methods not specifically mentioned are those known to those skilled in the art.
Example 1
The fluorescent carbon quantum dot comprises the following components in parts by weight: citric acid, formamide and tetraoctylammonium bromide, wherein: the volume ratio of the mass of the citric acid to the formamide is 2g:10mL.
A preparation method of fluorescent carbon quantum dots comprises the following steps:
(1) Taking 2g of citric acid as a carbon source and 10mL of formamide as a nitrogen source, adding the citric acid into 15mL of ethanol solution, stirring for 30 minutes, putting the mixture into a reaction kettle, performing hydrothermal synthesis at 160 ℃ for 7 hours, and filtering and centrifuging the mixture to obtain a carbon dot solution;
(2) Taking 10mL of the carbon dot solution prepared in the step (1), adding 1g of tetraoctyl ammonium bromide, stirring for 30 minutes, taking the supernatant orange-yellow luminous carbon dot, and purifying by a column chromatography, wherein the volume ratio is 1:1, methanol and methylene dichloride are used as developing agents to obtain the fluorescent carbon quantum dots.
Example 2
The fluorescent carbon quantum dot comprises the following components in parts by weight: citric acid, formamide and tetraoctylammonium bromide, wherein: the volume ratio of the mass of the citric acid to the formamide is 1g:5mL.
A preparation method of fluorescent carbon quantum dots comprises the following steps:
(1) Taking 1g of citric acid as a carbon source and 5mL of formamide as a nitrogen source, adding into 10mL of ethanol solution, stirring for 30 minutes, putting into a reaction kettle, performing hydrothermal synthesis at 140 ℃ for 6 hours, and filtering and centrifuging to obtain a carbon dot solution;
(2) Taking 5mL of the carbon dot solution prepared in the step (1), adding 0.1g of tetraoctyl ammonium bromide, stirring for 30 minutes, taking the orange-yellow luminous carbon dot of the supernatant, and purifying by a column chromatography, wherein the volume ratio is 1:1, methanol and methylene dichloride are used as developing agents to obtain the fluorescent carbon quantum dots.
Example 3
The fluorescent carbon quantum dot comprises the following components in parts by weight: citric acid, formamide and tetraoctylammonium bromide, wherein: the volume ratio of the mass of the citric acid to the formamide is 3g:15mL.
A preparation method of fluorescent carbon quantum dots comprises the following steps:
(1) Taking 3g of citric acid as a carbon source and 15mL of formamide as a nitrogen source, adding the citric acid into 20mL of ethanol solution, stirring for 30 minutes, putting the mixture into a reaction kettle, performing hydrothermal synthesis at 180 ℃ for 8 hours, and filtering and centrifuging the mixture to obtain a carbon dot solution;
(2) Taking 5mL of the carbon dot solution prepared in the step (1), adding 0.5g of tetraoctyl ammonium bromide, stirring for 30 minutes, taking the orange-yellow luminous carbon dot of the supernatant, and purifying by a column chromatography, wherein the volume ratio is 1:1, methanol and methylene dichloride are used as developing agents to obtain the fluorescent carbon quantum dots.
Example 4
The difference between the preparation method of the fluorescent carbon quantum dots in example 4 and the preparation method of the fluorescent carbon quantum dots in example 1 is that the cationic surfactant adopted in example 4 is didodecyl dimethyl ammonium bromide, and other preparation raw materials, the dosage and the technological parameters are the same as those in example 1.
Example 5
The difference between the preparation method of the fluorescent carbon quantum dots in example 5 and the preparation method of the fluorescent carbon quantum dots in example 1 is that the cationic surfactant adopted in example 5 is tetrahexylammonium bromide, and other preparation raw materials, the dosage and the process parameters are the same as those in example 1.
Example 6
The difference between the preparation method of the fluorescent carbon quantum dots in example 6 and the preparation method of the fluorescent carbon quantum dots in example 1 is that the cationic surfactant adopted in example 6 is diphenyl trimethyl ammonium bromide, and other preparation raw materials, the dosage and the technological parameters are the same as those in example 1.
Example 7
The difference between the preparation method of the fluorescent carbon quantum dots in example 7 and the preparation method of the fluorescent carbon quantum dots in example 1 is that the cationic surfactant adopted in example 7 is cetyltrimethylammonium bromide, and other preparation raw materials, the dosage and the technological parameters are the same as those in example 1.
Comparative example 1
The fluorescent carbon quantum dot comprises the following components in parts by weight: citric acid and formamide, wherein: the volume ratio of the mass of the citric acid to the formamide is 2g:10mL.
A preparation method of fluorescent carbon quantum dots comprises the following steps:
(1) Taking 2g of citric acid as a carbon source and 10mL of formamide as a nitrogen source, adding the citric acid into 15mL of ethanol solution, stirring for 30 minutes, putting the mixture into a reaction kettle, performing hydrothermal synthesis at 160 ℃ for 7 hours, and filtering and centrifuging the mixture to obtain a carbon dot solution;
(2) Taking 8mL of the carbon dot solution prepared in the step (1), stirring for 30 minutes, taking the orange-yellow luminous carbon dot of the supernatant, and purifying by column chromatography, wherein the volume ratio is 1:1, methanol and methylene dichloride are used as developing agents to obtain the fluorescent carbon quantum dots.
The difference between the preparation methods of the fluorescent carbon quantum dots of the comparative example 1 and the fluorescent carbon quantum dots of the example 1 is that the cationic surfactant passivation treatment is not performed in the comparative example 1, and other preparation raw materials, the use amounts thereof and the process parameters are the same as those of the example 1.
Performance testing
1. Optical performance test of fluorescent carbon quantum dots
The fluorescent carbon quantum dots prepared in the example 1 are added into ethanol solution to prepare fluorescent carbon quantum dot solutions with six concentrations of 28mg/mL, 14mg/mL, 7mg/mL, 3.5mg/mL, 1.75mg/mL and 0.875mg/mL, and fluorescence spectrum analysis is respectively carried out on the fluorescent carbon quantum dot solutions, and when the fluorescent carbon quantum dots are excited at 460nm, 3D spectrums of the fluorescent carbon quantum dots with different concentrations are obtained, as shown in fig. 1, wherein: a in FIG. 1 is a 3D spectrum of fluorescent carbon quantum dots with a concentration of 28 mg/mL; b in FIG. 1 is a 3D spectrum of fluorescent carbon quantum dots with a concentration of 14 mg/mL; c in FIG. 1 is the 3D spectrum of fluorescent carbon quantum dots at a concentration of 7 mg/mL; d in FIG. 1 is the 3D spectrum of fluorescent carbon quantum dots at a concentration of 3.5 mg/mL; d in FIG. 1 is the 3D spectrum of fluorescent carbon quantum dots at a concentration of 3.5 mg/mL; e in FIG. 1 is the 3D spectrum of fluorescent carbon quantum dots at a concentration of 1.75 mg/mL; f in FIG. 1 is the 3D spectrum of fluorescent carbon quantum dots at a concentration of 0.875 mg/mL; the abscissa Emission Wavelength represents the emission wavelength; the ordinate Excitation Wavelength represents the excitation wavelength.
As can be seen from fig. 1: when the relative concentration of the fluorescent carbon quantum dots is low (3.5 mg/mL, 1.75mg/mL and 0.875 mg/mL), only one emission peak exists; with the increase of the concentration, a new emission peak appears at 630nm at the concentration of 7 mg/mL; at a concentration of 14mg/mL, the emission peak at 630nm was enhanced; at a concentration of 28mg/mL, the emission peak at 630nm has become the dominant emission peak, which is mainly induced by the concentration of fluorescent carbon quantum dots. Therefore, when the fluorescent carbon quantum dot is excited at 460nm, the fluorescent carbon quantum dot has an emission peak of about 550-600 nm; meanwhile, the excitation peak position of the emission peak at 630nm induced by concentration is about 580nm, so that a serious self-absorption effect is generated, and the emission peak at 630nm is excited, so that the lacking red light component is compensated.
Fig. 2 is an emission spectrum of fluorescent carbon quantum dots with different concentrations, and fig. 2 shows that: with increasing concentration of fluorescent carbon quantum dots, a new emission peak appears, and the intensity of the emission peak gradually increases, and at 28mg/mL, a main emission peak is formed.
FIG. 3 is a graph showing the comparison of emission intensity of fluorescent carbon quantum dots of different concentrations, wherein: in the figure, λex=460 nm represents excitation wavelength of 460nm, and Y-CDs represents fluorescent carbon quantum dots; the abscissa concentration represents the concentration; the ordinate Intensity represents the emission Intensity; as can be seen from fig. 3: under the excitation of 460nm, the emission of 550nm is strongest at the concentration of 1.75mg/ml, which means that the reabsorption is weakest at the moment, which is consistent with the 630nm emission phenomenon which is generated by concentration aggregation induction and does not occur at low concentration.
LED light bead luminescence test
Adding the fluorescent carbon quantum dots prepared in the example 1 and the comparative example 1 into an ethanol solution to prepare a fluorescent carbon quantum dot solution with the concentration of 28mg/mL, and dispersing the solution to uniformly disperse the fluorescent carbon quantum dots in the ethanol solution; then adding mesoporous silica into the fluorescent carbon quantum dot solution to load the mesoporous silica into a pore structure of the mesoporous silica, and curing to obtain fluorescent carbon quantum dot powder; and finally, coating fluorescent carbon quantum dot powder on a 460nm blue light chip to obtain the LED light bead. The spectral data, CIE color coordinates, and excitation effect of the 3V power supply were measured for the LED beads and are shown in FIGS. 4-8, and FIG. 4 is as follows: CRI is the color rendering index; CCT is color temperature; the abscissa Wavelength represents Wavelength; the ordinate Intensity indicates the relative Intensity. As can be seen from fig. 4: under the induction of the concentration, the fluorescent carbon quantum dots in the embodiment 1 respectively generate a yellow light emission center and a red light emission center by the fluorescent carbon quantum dots excited by the 460nm blue light chip, so that the color rendering index is 89.2; warm white light emission with a color temperature 4570k and a light efficiency of 70.21 lm/W. As can be seen from fig. 5: the CIE coordinates of the example 1 lamp beads were (0.36, 0.38), which is a warm white light emission. As can be seen from fig. 6, the lamp beads prepared in example 1 emit warm white light. As can be seen from fig. 5: the CIE coordinates of the comparative example 1 lamp beads were (0.3268,0.3378), which was a cold white light emission. As can be seen from fig. 8, the lamp beads prepared in comparative example 1 emit cool white light.
3. Passivation effect test of different surfactants on fluorescent carbon quantum dots
The fluorescent carbon quantum dots prepared in example 1, examples 4 to 7 and comparative example 1 were measured in equal amounts and subjected to spectral test, and the test results are shown in fig. 9, and as can be seen from fig. 9: examples 1, 4-7, which were passivated with cationic surface activity, all had higher quantum efficiencies than comparative example 1, which was not passivated with cationic surface activity; when the cationic surfactant diphenyl trimethylammonium bromide with shorter chain is adopted for passivation (example 6), non-radiative transition is generated due to the too close distance between carbon points, so that the quantum efficiency is lower; the use of the longer chain cationic surfactants cetyltrimethylammonium bromide passivation (example 7) and didodecyl dimethyl ammonium bromide (example 5) reduces electron-hole radiative recombination, which also reduces the quantum efficiency of the carbon dots; the best quantum efficiency can be achieved only with cationic surfactants of suitable chain length, such as tetraoctylammonium bromide (example 1) and tetrahexylammonium bromide (example 4).
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While obvious variations or modifications are contemplated as falling within the scope of the present invention.
Claims (7)
1. The fluorescent carbon quantum dot is characterized in that raw material components for preparing the fluorescent carbon quantum dot consist of a carbon source, a nitrogen source and a cationic surfactant; the carbon source is citric acid, the nitrogen source is formamide, and the cationic surfactant is tetraoctyl ammonium bromide or tetrahexyl ammonium bromide; the volume ratio of the mass of the carbon source to the nitrogen source is (1-3) g: (5-15) mL;
The fluorescent carbon quantum dot is prepared by a preparation method comprising the following steps:
(1) Adding a carbon source and a nitrogen source into an organic solvent, performing solvothermal synthesis, filtering, and centrifuging to obtain a carbon dot solution; the organic solvent is ethanol;
(2) And (3) adding the carbon dot solution prepared in the step (1) into a cationic surfactant, mixing, taking supernatant, and purifying to obtain the fluorescent carbon quantum dot.
2. The method for preparing the fluorescent carbon quantum dot according to claim 1, comprising the following steps:
(1) Adding a carbon source and a nitrogen source into an organic solvent, performing solvothermal synthesis, filtering, and centrifuging to obtain a carbon dot solution; the organic solvent is ethanol;
(2) And (3) adding the carbon dot solution prepared in the step (1) into a cationic surfactant, mixing, taking supernatant, and purifying to obtain the fluorescent carbon quantum dot.
3. The method for preparing fluorescent carbon quantum dots according to claim 2, wherein in the step (1), the solvothermal synthesis temperature is 140-200 ℃; the solvothermal synthesis time is 6-8 hours.
4. The method of producing a fluorescent carbon quantum dot according to claim 2, wherein in the step (2), the volume ratio of the mass of the cationic surfactant to the carbon dot solution is (0.1-1) g: (5-15) mL.
5. The method for producing a fluorescent carbon quantum dot according to claim 2, wherein in the step (2), the purification is performed by column chromatography.
6. The use of the fluorescent carbon quantum dot according to claim 1, wherein the fluorescent carbon quantum dot is coated on the surface of a blue light chip after being cured, and the carbon quantum dot forms warm white light under the excitation of blue light.
7. An LED comprising the fluorescent carbon quantum dot of claim 1.
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| CN106675558A (en) * | 2017-01-16 | 2017-05-17 | 华南农业大学 | Carbon quantum dot/Eu<3+>/mesoporous alumina composite luminescent material and preparation and application thereof |
| CN110846030A (en) * | 2019-10-22 | 2020-02-28 | 五邑大学 | Single-component white-light carbon quantum dot, preparation method thereof and light-emitting device |
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