Carbon dot with water-phase laser emission characteristic and preparation method thereof

Abstract

The invention belongs to the field of novel display material quantum dot materials, and discloses a carbon dot with a dark blue light emission characteristic, and a preparation method and application thereof. The preparation method comprises the following steps: (1) weighing PTCDA and potassium carbonate according to a mass ratio of PTCDA to potassium carbonate of 1: (20-500); (2) putting PTCDA, potassium carbonate and water into a hydrothermal reaction kettle for hydrothermal reaction; wherein the ratio of the PTCDA to the water is 100 mg: (10-50) mL; and (3) after the hydrothermal reaction is completed, filtering, centrifuging and dialyzing a reaction solution, and finally drying to obtain the carbon dots. The carbon dots developed by the invention have the characteristic of water-phase laser emission, have wide application prospects, are simple in preparation process and low in cost, and are a convenient and environment-friendly method for synthesizing the carbon dots on a large scale.

Description

Technical Field

[0001] The present invention belongs to the field of new display devices and new display materials, quantum dot materials, under 1.3 electronic core industries key direction in the 1.3.2 new display devices of the catalog of strategic emerging industries 1. New generation information technology industry, and specifically relates to a carbon dot with water-phase laser emission characteristics and a preparation method thereof. Background Art

[0002] With the rapid development of laser technology, the types and performance of laser materials have been greatly improved. Traditional laser materials usually include inorganic semiconductor materials, dye lasers, and quantum dots. Although these materials have made breakthroughs in optical performance, most of them have limitations such as complex preparation processes, high costs, and poor environmental friendliness. In particular, they have encountered great challenges in achieving laser emission in aqueous solution systems. Based on this, finding a new type of laser material that has both efficient laser emission capabilities and environmental friendliness has become one of the current research hotspots.

[0003] Carbon dots are a new class of nanomaterials with excellent optical properties. Carbon dots have strong optical activity and have received extensive attention in recent years due to their high biocompatibility, low toxicity, and good stability. In particular, the stability of carbon dots in aqueous environments and their good water solubility enable them to show important application prospects in the fields of biomedicine, optoelectronic devices, sensors, etc. However, since the excitation and emission mechanism of carbon dots has not been fully revealed, it is extremely challenging to achieve efficient laser emission of carbon dots in aqueous phase.

[0004] Current research has proven that carbon dots can achieve laser emission under certain conditions, but these are usually carried out in organic solvents or solid matrices, and there are few reports of laser emission in aqueous environments. The aqueous system not only places higher demands on the optical properties of laser materials, but is also a greener and more environmentally friendly option. In contrast, the laser emission of carbon dots in aqueous phases provides a more environmentally friendly and low-cost solution, which is expected to replace some traditional laser materials. Summary of the invention

[0005] In order to break through the bottleneck of laser emission of carbon dots in aqueous solution, the purpose of the present invention is to provide a carbon dot with water-phase laser emission characteristics which is low-cost and easy to operate and a preparation method thereof.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing carbon dots with water-phase laser emission characteristics comprises the following steps: (1) Weigh PTCDA and potassium carbonate in a mass ratio of PTCDA: potassium carbonate = 1: (20-500); (2) Place PTCDA, potassium carbonate and water in a hydrothermal reactor for hydrothermal reaction; wherein PTCDA: water = 100 mg: (10-50) mL; (3) After the hydrothermal reaction is completed, the reaction solution is filtered, centrifuged, dialyzed, and finally dried to obtain carbon dots.

[0007] Preferably, the solvothermal reaction temperature is 160-240 °C and the time is 4-24 h.

[0008] Preferably, the pore size of the filter paper used for filtration is 1-100 μm.

[0009] Preferably, the centrifugation speed is 6000-12000 rpm and the time is 5-20 min.

[0010] Preferably, the dialysis bag used for dialysis has a molecular weight cutoff of 100-3000 Da, the dialysate is water, and the total dialysis time is 12-48 h.

[0011] A carbon dot with water-phase laser emission characteristics prepared by the preparation method.

[0012] In the present invention, PTCDA is slightly soluble in water, and potassium carbonate provides a weakly alkaline environment. Adding potassium carbonate can promote the ring opening of the perylene anhydride bond of PTCDA to form carboxylic acid, promote water solubility, and thus facilitate the hydrothermal reaction to synthesize carbon dots.

[0013] Beneficial effects: The carbon dots developed by the present invention have the characteristics of water-phase laser emission, have broad application prospects, and have a simple preparation process and low cost. It is a convenient and environmentally friendly method for large-scale synthesis of carbon dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 : XRD pattern of carbon dots prepared in Example 1.

[0015] Figure 2 : Transmission electron microscopy image of the carbon dots prepared in Example 1.

[0016] Figure 3 : Fluorescence excitation, fluorescence emission (excitation wavelength 365nm) and ultraviolet absorption spectra of the carbon dots prepared in Example 1.

[0017] Figure 4 : Quantum yield diagram of carbon dots prepared in Example 1.

[0018] Figure 5 : Laser emission spectrum of carbon dots prepared in Example 1.

[0019] Figure 6: Threshold curve of laser emission of carbon dots prepared in Example 1 (relationship between spectral intensity and spectral width and excitation light intensity). DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention.

[0021] Example 1

[0022] A method for preparing carbon dots with water-phase laser emission characteristics, the steps are as follows: (1) Take 100 mg of perylenetetracarboxylic dianhydride (PTCDA) powder and 10 g of potassium carbonate powder, add them into a 25 mL hydrothermal reactor, add 10 mL of water, and perform hydrothermal reaction at 200 °C for 8 h to obtain a green solution; (2) The green solution after the hydrothermal reaction in step (1) was filtered through filter paper with a pore size of 10 μm, and the filtrate was then centrifuged at 8000 rpm for 10 min. Finally, it was dialyzed in water for 20 h using a dialysis bag with a molecular weight cutoff of 1000 Da, and freeze-dried to obtain pure carbon dots (CDs).

[0023] Comparative Example 1 The difference from Example 1 is that the added amount of potassium carbonate is changed to 0 g, 0.5 g and 1.0 g respectively; the rest is the same as Example 1.

[0024] The results showed that after the hydrothermal reaction, the color of the system after the reaction was still red when observed with the naked eye. Considering that the raw material PTCDA itself is a red powder, it means that when no potassium carbonate is added or the amount of potassium carbonate is too small, there is almost no reaction! Figure 1 The XRD pattern of the carbon dots prepared in Example 1 of the present invention shows that o Characteristic peaks belonging to carbon appear on the left and right.

[0025] Figure 2 This is a transmission electron microscopy image of the carbon dots prepared in Example 1 of the present invention. It can be seen that the carbon dots exist and the sizes of the carbon dots are evenly distributed in the range of 3 to 6 nm.

[0026] The carbon dots prepared in Example 1 of the present invention were dispersed in water (carbon dots concentration 1 mg / mL), and the fluorescence spectrum, ultraviolet absorption spectrum, quantum yield and laser emission performance (using a 355 nm laser) were tested respectively.

[0027] Figure 3 The fluorescence excitation (PLE), fluorescence emission (PL, excitation wavelength 365 nm) and ultraviolet absorption spectrum (UV-Vis) of the carbon dots prepared in Example 1 of the present invention at room temperature. Figure 3 It can be seen that the carbon dots have a strong green emission peak at 511 nm and a shoulder peak at 550 nm, indicating that the prepared carbon dots have green fluorescence; the UV-visible absorption spectrum shows two absorption bands: one at 250 nm, corresponding to the π-π* transition of the conjugated structure in the carbon dots, and the other between 400 and 500 nm, which may correspond to the absorption of different energy levels generated by the aggregation of the conjugated structure in the carbon dots.

[0028] Figure 4 The quantum yield diagram of carbon dots and water prepared in Example 1 of the present invention, wherein the sample corresponding to Blank is water, and the sample corresponding to CDs is the carbon dots prepared in Example 1. Figure 4 It can be seen that the prepared carbon dots have a very high quantum yield (PLQY=86.76%), which is at a relatively high level in the field of carbon dots.

[0029] Figure 5 This is the laser emission spectrum of the carbon dots prepared in Example 1 of the present invention. Figure 5 It can be seen that the laser emission peak is 512 nm, and as the energy density of the excitation light increases, the laser emission intensity increases.

[0030] Figure 6 is the threshold curve of laser emission of carbon dots prepared in Example 1 of the present invention. Figure 6 It can be seen that the laser threshold of carbon dots is 7.5 mJ / cm 2 . It is fully explained that carbon dots dispersed in water can achieve the properties of laser emission, and the threshold is very low, which is in a very leading position in the field.

Claims

1. A method for preparing carbon dots with water-phase laser emission characteristics, characterized in that: The following steps are involved: (1) Weigh PTCDA and potassium carbonate in a mass ratio of PTCDA: potassium carbonate = 1: (20-500); (2) Place PTCDA, potassium carbonate and water in a hydrothermal reactor for hydrothermal reaction; wherein PTCDA: water = 100 mg: (10-50) mL; (3) After the hydrothermal reaction is completed, the reaction solution is filtered, centrifuged, dialyzed, and finally dried to obtain carbon dots.

2. The method for preparing carbon dots with water-phase laser emission characteristics according to claim 1, characterized in that: The temperature of the solvothermal reaction is 160~240 ℃ and the time is 4~24 h.

3. The method for preparing carbon dots with water-phase laser emission characteristics according to claim 1, characterized in that: The pore size of the filter paper used for filtration is 1~100 μm.

4. The method for preparing carbon dots with water-phase laser emission characteristics according to claim 1, characterized in that: The centrifugal speed is 6000~12000 rpm and the time is 5~20 min.

5. The method for preparing carbon dots with water-phase laser emission characteristics according to claim 1, characterized in that: The dialysis bag used for dialysis has a molecular weight cutoff of 100~3000 Da, the dialysate is water, and the total dialysis time is 12~48 h.

6. A carbon dot having water-phase laser emission characteristics prepared by the preparation method according to any one of claims 1 to 5.

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