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High quantum yield carbon dots with tunable eigenstate fluorescence and its preparation and application

An eigenstate, high quantum technology, applied in light-emitting materials, chemical instruments and methods, semiconductor devices, etc., can solve the problems of low performance of light-emitting diode devices, limited effective injection of carriers, and changes in fluorescence emission peaks. The effect of high yield, high crystallinity, and simple method

Active Publication Date: 2019-07-16
BEIJING NORMAL UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The carbon dots currently reported in the literature often have poor crystallinity, and the surface often contains a large number of defects, which in turn will generate a large number of defect state energy levels, so that the fluorescence of carbon dots is often dominated by the surface defect states, showing that the fluorescence emission peak position varies with the excitation wavelength. Fluorescent properties of defect states that change
For the application of optoelectronic devices such as electroluminescent diodes, the defect state fluorescence of carbon dots greatly limits the effective injection of carriers, making the performance of light-emitting diodes very low, which greatly limits its application in the field of electroluminescent diodes. Applications
[0004] At present, although the excitation-independent intrinsic state fluorescent carbon dots can be prepared using aniline as a precursor, its quantum yield is relatively low (20%).
Using a simple method to prepare carbon dots with high quantum yield and tunable intrinsic state fluorescence whose fluorescence emission peak does not change with the excitation wavelength is still a big challenge

Method used

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  • High quantum yield carbon dots with tunable eigenstate fluorescence and its preparation and application
  • High quantum yield carbon dots with tunable eigenstate fluorescence and its preparation and application
  • High quantum yield carbon dots with tunable eigenstate fluorescence and its preparation and application

Examples

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Effect test

Embodiment 1

[0044] Example 1, the preparation of blue-light carbon dots with a quantum yield of 75% intrinsic state

[0045]Weigh 0.01 g of 2,3-diaminonaphthalene and citric acid solids, with a mass ratio of 1:1, and dissolve them in 10 ml of ethanol with ultrasonic stirring. 0.1 ml of concentrated sulfuric acid was added into the reaction system as a reaction catalyst. The above solution was transferred to a polytetrafluoroethylene-lined stainless steel autoclave with a capacity of 25 ml, and the lid of the autoclave was tightened. Solvothermal reaction at 140°C for 4 hours, then let the reactor cool down to room temperature naturally, so as to obtain a light yellow ethanol solution with carbon dots, and then neutralize it with 20ml of 0.01 mole per liter of sodium hydroxide aqueous solution to neutrality, and then filter , take the filtrate and place it in a dialysis bag (1000 Da) for dialysis in deionized water for two days, changing the deionized water every three hours. After the d...

Embodiment 2

[0049] Example 2, the preparation of quantum yield is 73% intrinsic state green light carbon dots

[0050] The specific steps are the same as in Example 1, except that the precursor 2,3-diaminonaphthalene and citric acid solids are 0.1 and 0.01 g respectively, the mass ratio is 10:1, the reaction temperature is 180° C., and the solvothermal reaction time is 9 hours. The resulting dilute solution of carbon dots in ethanol emits bright green fluorescence under a portable ultraviolet lamp (365nm), and the green light carbon dots show excitation-independent intrinsic state fluorescence characteristics ( Figure 10 ), the emission peak is located at 513nm. Green carbon dots have high crystallinity, with an average particle size of 2.41nm ( Figure 11 ). The absolute fluorescence quantum yield was measured as high as 73%.

Embodiment 3

[0051] Example 3, the preparation of 58% intrinsic state yellow light carbon dots with a quantum yield

[0052] The specific steps are the same as in Example 1, except that the precursors are 1,5-diaminonaphthalene and citric acid, the masses are 0.04 and 0.01 g respectively, the mass ratio is 4:1, and the volume-to-mass ratio of ethanol to the carbon source precursor is mL / The mg ratio is 1:5, the reaction temperature is 200°C, and the solvothermal reaction time is 9 hours. The resulting dilute ethanol solution of carbon dots emits bright yellow fluorescence under a portable ultraviolet lamp (365nm), and the yellow light carbon dots show excitation-independent intrinsic state fluorescence characteristics ( Figure 12 ), the emission peak is located at 535nm. The yellow light carbon dots have high crystallinity, and the average particle size is 3.78nm ( Figure 13 ). The absolute fluorescence quantum yield was measured as high as 58%.

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Abstract

The invention relates to the field of fluorescent carbon nanomaterials, in particular to carbon dots with high quantum yield and adjustable eigenstate fluorescence, as well as their preparation method and application. Using diaminonaphthalene or its hydroxyl, carboxyl, methyl, ethyl, N,N-dimethyl and N,N-diethyl substituted derivatives and citric acid as the carbon source precursor, it can be obtained by solvothermal method Intrinsic fluorescent carbon dot solution. The intrinsic state fluorescent carbon dots prepared by the invention have the characteristics of high crystallinity, high surface passivation degree, nitrogen doping, uniform particle size distribution and the like, and have wide application prospects.

Description

technical field [0001] The invention relates to the field of fluorescent carbon nanomaterials, in particular to carbon dots with high quantum yield and adjustable eigenstate fluorescence, as well as their preparation method and application. Background technique [0002] Carbon dots (CDs), as a new type of carbon nanomaterial with a size less than 10nm, are widely used in optoelectronics due to their low toxicity, good biocompatibility, chemical inertness, stable fluorescent properties, and better surface modification capabilities. Devices, biomedicine, and sensors have broad application prospects. The current methods for preparing carbon dots are mainly divided into two categories: top-down and bottom-up. The top-down method generally uses bulk carbon materials as carbon sources, such as graphite, carbon fiber, carbon nanotubes, carbon black, coal, etc., and obtains carbon dots through violent oxidation and exfoliation. The bottom-up method mainly uses organic small molecu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K11/65H01L33/50
Inventor 范楼珍袁方龙杨世和
Owner BEIJING NORMAL UNIVERSITY