Preparation method of carbon quantum dots with ultraviolet light excitation white light emission
Ultraviolet-excited white-light carbon dots were prepared by hydrothermal reaction of low molecular weight polymers and aniline precursors, solving the problem of aggregation-induced quenching of carbon dots in the solid state and achieving stable white light emission and efficient solid-state luminescence.
Patent Information
- Application Number
- CN202610451034.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-08
- Publication Date
- 2026-07-14
AI Technical Summary
Existing carbon dots exhibit severe aggregation-induced quenching in the solid state, resulting in low solid-state luminescence efficiency and making them unsuitable for direct use in solid-state light-emitting devices.
Carbon quantum dots that emit white light under ultraviolet light are prepared by using low molecular weight polymers and aniline precursors through hydrothermal reaction and dialysis. Their core structure and surface chemical environment are controlled to suppress aggregation-induced quenching.
The stability and controllability of the solid-state luminescence performance of carbon dots emitting white light under ultraviolet light excitation were achieved, reducing aggregation-induced quenching effects and improving solid-state luminescence efficiency.
Smart Images
Figure CN122381801A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a method for preparing carbon quantum dots that emit white light when excited by ultraviolet light. Background Technology
[0002] Carbon dots, as an important member of the zero-dimensional carbon nanomaterial family, have attracted widespread attention since their accidental discovery in 2004 due to their unique optical properties (such as photoluminescence and electroluminescence), low toxicity, good biocompatibility, ease of functionalization, and high stability. Their size is typically less than 10 nanometers, combining the excellent chemical stability of carbon materials with the luminescent properties of quantum dots. In recent years, carbon dots that achieve white light emission have become a cutting-edge research topic in the field of optoelectronic materials, and are considered environmentally friendly candidate materials to replace traditional heavy metal-containing quantum dots (such as CdSe) and rare-earth phosphors, showing great potential in fields such as solid-state lighting and high-definition displays.
[0003] Despite its promising prospects, the transition of white-light-emitting carbon dots from the laboratory to large-scale industrial applications still faces a series of key scientific and technological challenges. The most significant of these are low solid-state luminescence efficiency and the prevalent aggregation-induced quenching effect. Carbon dots typically exhibit high fluorescence quantum yields in solution, but once fabricated into solid films or powders, energy transfer or π-π interactions due to close packing between particles lead to severe aggregation-induced fluorescence quenching. This prevents many high-performance solution-based carbon dots from being directly used in solid-state light-emitting devices, becoming the primary bottleneck restricting the improvement of white-light luminescence efficiency based on carbon dots.
[0004] The advantages of this invention stem from the unique determinism and designability of low molecular weight polymers. Their well-defined molecular structures (such as repeating units, chain lengths, and terminal functional groups) act as both "molecular templates" and "structure guides" during carbonization, enabling more precise control over the core structure and surface chemical environment of the generated carbon dots. While effectively suppressing solid-state aggregation-induced quenching, it also allows for controllable and tunable luminescence performance. The preparation of solid-state luminescent carbon dots using low molecular weight polymers and aniline precursors represents an advanced material preparation strategy that starts from molecular design, combining structural precision and functional guidance. It is not only an effective path to solve the problem of solid-state quenching of carbon dots but also promotes the transition of carbon dots from laboratory luminescent materials to practical optoelectronic device applications, possessing extremely high technological value and industrialization potential. Summary of the Invention
[0005] To address the problem of aggregation-induced quenching of traditional carbon dots in the solid state and the practical application requirements of single-phase white light emission, the present invention aims to provide a method for preparing carbon dots that generate white light emission under ultraviolet light excitation. The method is simple to operate, low in cost, and the detection results have good reproducibility.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing carbon quantum dots that emit white light under ultraviolet light excitation includes the following steps:
[0008] 1) Dissolve aniline chemicals in deionized water. After complete dissolution, add low molecular weight polymers and continue stirring until a homogeneous and transparent mixed solution is obtained.
[0009] 2) Transfer the mixed solution obtained in step 1) to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction, and allow it to cool naturally to room temperature after the reaction is complete;
[0010] 3) After the hydrothermal reaction in step 2), the material obtained is transferred to a dialysis bag for dialysis. After dialysis, it is freeze-dried and purified to obtain powdered carbon quantum dots, which are the carbon quantum dots that can emit white light under ultraviolet light excitation. After collection, they are immediately sealed and stored in a cold storage.
[0011] Furthermore, in the above preparation method, in step 1), the ratio of the aniline chemical to deionized water is (100-1000) mg: (10-100) mL.
[0012] Furthermore, in the above preparation method, in step 1), the weight ratio of the low molecular weight polymer to the aniline chemical is 1:(0.5~100).
[0013] Furthermore, in the above preparation method, in step 1), the aniline chemical is one or more of o-phenylenediamine, m-phenylenediamine, p-aminobenzoic acid, triaminobenzene, aminophenylboronic acid, o-toluidine, and aminochlorophenylboronic acid.
[0014] Furthermore, in the above preparation method, in step 1), the low molecular weight polymer is one or more of polyethyleneimine, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and polylysine.
[0015] Furthermore, in the above preparation method, in step 2), the hydrothermal reaction temperature is 160-260 ℃, and the hydrothermal reaction time is 6-24 hours.
[0016] Furthermore, in the above preparation method, step 3), the molecular weight cutoff of the dialysis bag is 200-7000 Da.
[0017] Furthermore, in the above preparation method, step 3), the dialysis time is 6-48 hours.
[0018] The beneficial effects of this invention are:
[0019] 1. The carbon dots prepared by this invention that can emit white light under ultraviolet light excitation use aniline chemicals and low molecular weight polymers as precursors. The raw materials are simple and the preparation method is easy, which can significantly improve the preparation efficiency.
[0020] 2. The carbon dots prepared by this invention that can emit white light under ultraviolet light excitation can significantly reduce the influence of aggregation-induced quenching effect, thereby enabling the carbon dots to exhibit solid-state luminescence.
[0021] 3. The carbon dots prepared by this invention that can emit white light under ultraviolet light excitation have a large half-width and multiple emission sites, ensuring that the material can emit stable white light. Attached Figure Description
[0022] Figure 1 This is a transmission electron microscope (TEM) image of carbon quantum dots.
[0023] Figure 2 The emission spectrum of carbon quantum dots under 360 nm excitation.
[0024] Figure 3 This is the CIE coordinate diagram corresponding to the emission spectrum of carbon quantum dots under 360 nm excitation. Detailed Implementation
[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0026] Example 1
[0027] A carbon quantum dot capable of emitting white light under ultraviolet light excitation is prepared using the following method:
[0028] 1) Take 200 mg of o-phenylenediamine (o-PD) and dissolve it in 20 mL of deionized water at room temperature and with stirring. After complete dissolution, add 10 mg of polyethyleneimine (PEI) and continue stirring slowly until a homogeneous and transparent solution is obtained.
[0029] 2) Transfer the solution obtained in step 1) to a hydrothermal reactor lined with polytetrafluoroethylene and maintain it at 180 °C for 8 hours. After the reaction is complete and the solution temperature drops to room temperature, remove the material obtained after the reaction.
[0030] 3) Transfer the extracted material to a dialysis bag with a molecular weight cutoff of 2000 Da and dialyze for 24 hours. After dialysis, perform freeze-drying purification, collect the powder sample, and obtain white light emitting carbon quantum dots. Immediately seal and refrigerate after collection.
[0031] Example 2
[0032] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 1), 100 mg of o-phenylenediamine and 100 mg of polyethyleneimine are used, that is, the weight ratio of polyethyleneimine to o-phenylenediamine is 1:1, and the remaining steps remain unchanged.
[0033] Example 3
[0034] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 2), the hydrothermal reaction temperature is 200°C, while the other steps remain unchanged.
[0035] Example 4
[0036] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 2), the hydrothermal reaction time is 12 hours, while the other steps remain unchanged.
[0037] Example 5
[0038] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 3), the dialysis time is 12 hours, while the other steps remain unchanged.
[0039] Example 6
[0040] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 1), the volume of deionized water is replaced with 10 mL, while the other steps remain unchanged.
[0041] Example 7
[0042] The preparation of a carbon quantum dot that can emit white light under ultraviolet light excitation differs from Example 1 in that: in step 3), the molecular weight cutoff of the dialysis bag is 1000 Da, while the other steps remain unchanged.
[0043] The carbon quantum dots prepared in Example 1 were characterized, and the fluorescent probe was found to emit white fluorescence under ultraviolet light excitation.
[0044] Figure 1 The transmission electron microscopy characterization results of the prepared carbon quantum dots show that the carbon quantum dots are well dispersed and their size distribution is in the range of 1-10 nm.
[0045] Figure 2 The figure shows the fluorescence spectrum of the prepared carbon quantum dots in the solid state. It can be seen from the figure that they exhibit significant photoluminescence in the visible light range, with more pronounced luminescence in the blue and yellow-green light ranges.
[0046] Figure 3The coordinates of the prepared carbon quantum dots in the CIE were calculated based on their fluorescence data. It can be seen that the photoluminescence of these carbon quantum dots falls within the white light range.
[0047] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.
Claims
1. A method for preparing carbon quantum dots that emit white light under ultraviolet light excitation, characterized in that, Includes the following steps: 1) Dissolve aniline chemicals in deionized water. After complete dissolution, add low molecular weight polymers and continue stirring until a homogeneous and transparent mixed solution is obtained. 2) Transfer the mixed solution obtained in step 1) to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction, and allow it to cool naturally to room temperature after the reaction is complete; 3) After the hydrothermal reaction in step 2), the material obtained is transferred to a dialysis bag for dialysis. After dialysis, it is freeze-dried and purified to obtain powdered carbon quantum dots, which are the carbon quantum dots that can emit white light under ultraviolet light excitation. After collection, they are immediately sealed and stored in a cold storage.
2. The preparation method according to claim 1, characterized in that, In step 1), the ratio of the aniline chemical to deionized water is (100-1000) mg: (10-100) mL.
3. The preparation method according to claim 1, characterized in that, In step 1), the weight ratio of the low molecular weight polymer to the aniline chemical is 1:(0.5~100).
4. The preparation method according to claim 1, characterized in that, In step 1), the aniline chemical is one or more of o-phenylenediamine, m-phenylenediamine, p-aminobenzoic acid, triaminobenzene, aminophenylboronic acid, o-toluidine, and aminochlorophenylboronic acid.
5. The preparation method according to claim 1, characterized in that, In step 1), the low molecular weight polymer is one or more of polyethyleneimine, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and polylysine.
6. The preparation method according to claim 1, characterized in that, In step 2), the hydrothermal reaction temperature is 160-260 ℃ and the hydrothermal reaction time is 6-24 hours.
7. The preparation method according to claim 1, characterized in that, In step 3), the molecular weight cutoff of the dialysis bag is 200-7000 Da.
8. The preparation method according to claim 1, characterized in that, In step 3), the dialysis time is 6-48 hours.