Nitrogen-doped carbonized polymer dots, preparation method and application thereof

Abstract

The application provides a kind of based on nitrogen-doped carbonized polymer dots, preparation method and application thereof.The based on nitrogen-doped carbonized polymer dots in the application can be blended with silicone sol in any proportion, and has different fluorescence performance.The mass ratio of the based on nitrogen-doped carbonized polymer dots to the silicone sol in the application has a wide control range, and by simply adjusting the mass ratio of the based on nitrogen-doped carbonized polymer dots to the silicone sol or selecting LED chips with different emission wavelengths, a full-color light-emitting multicolor LED that can emit blue light, green light, yellow light, orange light, red light and white light can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a nitrogen-doped carbonized polymer dot, its preparation method, and its application. Background Technology

[0002] LEDs have become the mainstream display and lighting technology due to their advantages such as fast response, high energy efficiency, small size, and long lifespan. Multicolor LEDs are widely used because of their diverse color emission. Currently, the photoluminescent materials used in multicolor LEDs mainly include rare-earth-based nanoparticles, perovskite quantum dots, semiconductor quantum dots, and organic dyes. However, the application of these materials in LEDs is limited by factors such as complex synthesis processes, toxicity, and poor stability. Developing novel fluorescent materials is an effective strategy to solve these problems.

[0003] Carbonized polymer dots (CPDs) have higher thermal and light stability than organic dyes and good compatibility with some matrix materials. They can be uniformly dispersed at high concentrations, so more and more studies are applying CPDs to multicolor LEDs. For example: using avocado as raw material, a series of carbonized polymer dots without solid fluorescence were prepared by changing the reaction temperature through a high-temperature hydrothermal method. These dots were then dispersed in epoxy resin to achieve emission from blue to yellow light. Using ethylenediamine and polyvinyl alcohol as raw materials, green solid carbonized polymer dots under 340nm excitation were prepared by a one-pot hydrothermal method. Orange and white LED devices were then prepared by utilizing the redshift of fluorescence induced by the aggregation of the carbonized polymer dots. Using o-phenylenediamine and L-tryptophan as raw materials, three types of carbonized polymer dots were prepared by hydrothermal method by adjusting the pH value of the hydrochloric acid reaction system. These were then used to prepare blue, yellow, and red LEDs. Using ethylenediamine, trimethylolpropane triglycidyl ether, and carbon dioxide as raw materials, solid carbonized polymer dots that emit blue light under 360nm excitation were obtained through multiple steps under hydrothermal conditions. These carbon dots were then applied to multi-color LEDs that emit white, yellow, orange, and red light.

[0004] In summary, LEDs designed and constructed using solid-state fluorescent carbonized polymer dots can achieve multi-color emission by utilizing the characteristics of carbonized polymer dots. However, using small molecules as raw materials and a simple one-step solvothermal method to prepare carbonized polymer dots makes it difficult to fabricate full-color LEDs, which greatly limits their application in LED devices. Therefore, there is an urgent need to develop an effective and simple method to achieve full-color fluorescent controllable LED fabrication. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a nitrogen-doped carbonized polymer dot, its preparation method, and its application.

[0006] This invention provides a method for preparing nitrogen-doped carbonized polymer dots, comprising the following steps:

[0007] Citric acid, urea, and polymeric monomers are added to ethanol and mixed evenly to obtain a mixed reaction solution. The polymeric monomers are hydroxyethyl methacrylate or acrylonitrile.

[0008] The mixed reaction solution is subjected to a solvothermal reaction under preset reaction conditions to obtain a polymerization product;

[0009] The polymerization product is purified to obtain the nitrogen-doped carbonized polymer dots.

[0010] Preferably, the preset reaction conditions include a reaction temperature and a reaction time, wherein the reaction temperature is 100℃~300℃ and the reaction time is 4h~24h.

[0011] Preferably, the molar ratio of citric acid to the polymeric monomer is 1:0.1 to 1:50.

[0012] Preferably, the molar ratio of urea to the polymer monomer is 1:0.1 to 1:50.

[0013] In another aspect, the present invention provides a nitrogen-doped carbonized polymer dot, which is prepared by the above-described method for preparing nitrogen-doped carbonized polymer dots.

[0014] The present invention also provides the application of the above-mentioned nitrogen-doped carbonized polymer dots in the preparation of multicolor LEDs.

[0015] Preferably, the nitrogen-doped carbonized polymer dots are dispersed in an organosilicon sol at a preset ratio to form a composite material, which is then dropped onto an LED chip and cured to obtain a multicolor LED.

[0016] Preferably, the mass ratio of nitrogen-doped carbonized polymer dots to organosilicon sol in the composite material is 0.0015:1 to 1:1.

[0017] Preferably, the method for preparing the organosilicon sol includes the following steps:

[0018] Water is mixed with a suitable solvent to form a mixed solvent;

[0019] The silane is dispersed in the mixed solvent to form a silane reaction solution;

[0020] The silane reaction solution is stirred at room temperature to form the organosilicon sol.

[0021] Preferably, the suitable solvent is one or a combination of ethanol, acetone, methanol, and ethylene glycol, and the silane is one or a combination of 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, phenyltriethyloxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, or γ-ureopropyltriethoxysilane.

[0022] Experiments show that the nitrogen-doped carbonized polymer dots described in this application can be blended with the organosilicon sol in any proportion and have different fluorescence properties. The mass ratio of the nitrogen-doped carbonized polymer dots to the organosilicon sol described in this application has a wide controllable range. Furthermore, by simply adjusting the mass ratio of the nitrogen-doped carbonized polymer dots to the organosilicon sol or by selecting LED chips with different emission wavelengths, a full-color LED that emits blue, green, yellow, orange, red, and white light can be obtained. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the preparation of the multicolor LEDs obtained in Examples 4 to 14 of the present invention;

[0024] Figure 2 These are schematic diagrams showing the working state of the multicolor LEDs prepared in Examples 4 to 8 of the present invention.

[0025] Figure 3 This is a schematic diagram showing the working light, emission spectrum, and color coordinates of the multicolor LEDs prepared in Examples 9 to 14 of this invention during operation.

[0026] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0027] This invention provides a nitrogen-doped carbonized polymer dot, its preparation method, and its application. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The method and application of this invention have been described through preferred embodiments, and those skilled in the art will clearly be able to modify or appropriately change and combine the method and application described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0028] The method for preparing nitrogen-doped carbon polymer dots described in this invention uses small molecules as raw materials and employs a solvothermal method to prepare and purify the nitrogen-doped carbon polymer dots. The application of nitrogen-doped carbon polymer dots in the preparation of multicolor LEDs includes the preparation of a matrix material. The nitrogen-doped carbon polymer dots exhibit good compatibility with the matrix material and possess tunable solid-state fluorescence. The multicolor LEDs prepared from the nitrogen-doped carbon polymer dots and matrix material have a high loading of carbon polymer dots in the matrix. Furthermore, as the concentration of carbon polymer dots increases, the solid-state fluorescence emission wavelength also changes. This allows for precise control of full-color emission from blue to red and white light. The preparation method is simple, offers full-color tunability, and provides a wide range of tunable fluorescence.

[0029] In this invention, citric acid, urea, and a suitable solvent are added to ethanol and mixed evenly to obtain a mixed reaction solution; the mixed reaction solution is subjected to a solvothermal reaction under preset reaction conditions to obtain a polymerization product; the polymerization product is purified to obtain the nitrogen-doped carbonized polymer dots; the nitrogen-doped carbonized polymer dots emit yellow light when excited by light with a wavelength of 365 nm.

[0030] In this invention, in the step of purifying the polymer product to obtain the nitrogen-doped carbonized polymer dots, the purification process is extraction, column chromatography, or dialysis.

[0031] In this invention, when preparing the organosilicon sol, the silane reaction solution is stirred at room temperature for a preset time, which is 1 to 7 days.

[0032] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.0015 to 1:0.01. The prepared composite material is coated on a 365nm LED chip and cured in an oven at 40℃ to 60℃ to obtain a blue LED device.

[0033] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.01 to 1:0.05. The prepared composite material is coated on a 365nm LED chip and cured in an oven at 40℃ to 60℃ to obtain a green LED device.

[0034] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.05 to 1:0.09. The prepared composite material is coated on a 450nm LED chip and cured in an oven at 40℃ to 60℃ to obtain a white LED device.

[0035] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.05 to 1:0.18. The prepared composite material is coated on a 395nm LED chip and cured in an oven at 40℃ to 60℃ to obtain a yellow LED device.

[0036] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.25 to 1:0.50. The prepared composite material is coated on a 395nm LED chip and cured in an oven at 40℃ to 60℃ to obtain an orange LED device.

[0037] In this invention, the mass ratio of the organosilicon sol and the nitrogen-doped carbonized polymer dots is adjusted to 1:0.67 to 1:1. The prepared composite material is coated on a 395nm LED chip and cured in an oven at 40℃ to 60℃ to obtain a red LED device.

[0038] Unless otherwise specified, all raw materials used in this invention are commercially available products or obtained through conventional means in the art. The invention is further illustrated below with reference to the embodiments:

[0039] Example 1

[0040] 2.81 mmol of anhydrous citric acid, 17.98 mmol of urea, and 57.71 mmol of hydroxyethyl methacrylate were dissolved in 20 mL of ethanol and mixed thoroughly. The mixture was transferred to a reaction vessel and placed in a 180°C oven for 12 h. After natural cooling to room temperature, the resulting brown liquid was the polymerization product. The polymerization product was centrifuged twice at 10,000 rpm for 10 min each time to remove insoluble precipitates. Purification was performed with petroleum ether until the upper layer was colorless and transparent. The resulting lower layer was dried in a 40°C vacuum oven for 24 h to obtain brownish-yellow solid nitrogen-doped carbonized polymer dots, i.e., the nitrogen-doped carbonized polymer dots, which exhibited yellow fluorescence (543 nm) under 365 nm UV excitation.

[0041] Example 2

[0042] 2.81 mmol of anhydrous citric acid, 17.98 mmol of urea, and 106.32 mmol of acrylonitrile were dissolved in 20 mL of ethanol and mixed thoroughly. The mixture was transferred to a reaction vessel and placed in a 180°C oven for 12 h. After natural cooling to room temperature, the resulting brown liquid was the polymerization product. The polymerization product was centrifuged twice at 10,000 rpm for 10 min each time to remove insoluble precipitates. Purification was performed with petroleum ether until the upper layer was colorless and transparent. The resulting lower layer was dried in a 40°C vacuum oven for 24 h to obtain yellow solid nitrogen-doped carbonized polymer dots, i.e., the nitrogen-doped carbonized polymer dots, which exhibited yellow fluorescence (570 nm) under 365 nm UV excitation.

[0043] Example 3

[0044] The organosilicon sol, i.e. the matrix material, was prepared by stirring 20 mL of APTS, 14 mL of ultrapure water and 6 mL of ethanol at room temperature for 24 h.

[0045] Example 4

[0046] 0.0015g of the nitrogen-doped carbonized polymer dots prepared in Example 2 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 365nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a blue LED device.

[0047] Example 5

[0048] 0.01g of the nitrogen-doped carbonized polymer dots prepared in Example 2 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 365nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a green LED device.

[0049] Example 6

[0050] 0.05g of the nitrogen-doped carbonized polymer dots prepared in Example 2 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed evenly to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a yellow LED device.

[0051] Example 7

[0052] 0.33g of the nitrogen-doped carbonized polymer dots prepared in Example 2 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed evenly to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain an orange LED device.

[0053] Example 8

[0054] 0.82g of the nitrogen-doped carbonized polymer dots prepared in Example 2 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a red LED device.

[0055] Example 9

[0056] 0.005g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 365nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a blue LED device.

[0057] Example 10

[0058] 0.05g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 365nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a green LED device.

[0059] Example 11

[0060] 0.05g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed evenly to form the composite material. The composite material was then added dropwise to a purchased 450nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a white LED device.

[0061] Example 12

[0062] 0.11g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a yellow LED device.

[0063] Example 13

[0064] 0.33g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed evenly to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain an orange LED device.

[0065] Example 14

[0066] 0.82g of the nitrogen-doped carbonized polymer dots prepared in Example 1 and 1g of the organosilicon sol prepared in Example 3 were ultrasonically mixed evenly to form the composite material. The composite material was then added dropwise to a purchased 395nm ultraviolet light-emitting chip and cured in an oven at 40℃~60℃ for 3h to obtain a red LED device.

[0067] Please see Figure 1 The nitrogen-doped carbonized polymer dots have good compatibility with the organosilicon sol. The composite material prepared by the nitrogen-doped carbonized polymer dots and the organosilicon sol realizes full-color light emission of multi-color LEDs, solving the problem that carbonized polymer dots are difficult to achieve full-color light emission of multi-color LEDs.

[0068] Please see Figure 2 Multicolor LEDs can be fabricated using only a single nitrogen-doped carbonized polymer dot, simplifying the production process. In practical applications, different composite materials prepared with different contents of the nitrogen-doped carbonized polymer dot can be flexibly selected for the fabrication of multicolor LEDs.

[0069] Please see Figure 3 The multicolor LEDs prepared from nitrogen-doped carbonized polymer dots have high color saturation.

[0070] The nitrogen-doped carbonized polymer dots can not only achieve the preparation of full-color LEDs by controlling their concentration in the encapsulation material, but also have a wide controllable range. Within a certain content range, corresponding fluorescent colors can be achieved, which greatly simplifies its application in multicolor LEDs.

[0071] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An application of nitrogen-doped carbonized polymer dots in the fabrication of multicolor LEDs, characterized in that, The nitrogen-doped carbonized polymer dots are dispersed in an organosilicon sol at a preset ratio to form a composite material. The composite material is then dropped onto an LED chip and cured to obtain a multicolor LED. The preparation method based on nitrogen-doped carbonized polymer dots includes the following steps: Citric acid, urea, and polymeric monomers are added to ethanol and mixed evenly to obtain a mixed reaction solution. The polymeric monomer is hydroxyethyl methacrylate or acrylonitrile. The molar ratio of citric acid to polymeric monomer is 1:0.1 to 1:50, and the molar ratio of urea to polymeric monomer is 1:0.1 to 1:

50. The mixed reaction solution is subjected to a solvothermal reaction under preset reaction conditions to obtain a polymerization product; The polymerization product is purified to obtain the nitrogen-doped carbonized polymer dots.

2. The application according to claim 1, characterized in that, The preset reaction conditions include reaction temperature and reaction time, wherein the reaction temperature is 100℃~300℃ and the reaction time is 4h~24h.

3. The application according to claim 1, characterized in that, The mass ratio of nitrogen-doped carbonized polymer dots to organosilicon sol in the composite material is 0.0015:1 to 1:

1.

4. The application according to claim 1, characterized in that, The preparation method of the organosilicon sol includes the following steps: Water is mixed with a suitable solvent to form a mixed solvent; The silane is dispersed in the mixed solvent to form a silane reaction solution; The silane reaction solution is stirred at room temperature to form the organosilicon sol.

5. The application according to claim 4, characterized in that, The suitable solvent is one or a combination of several of ethanol, acetone, methanol, and ethylene glycol, and the silane is one or a combination of several of 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, phenyltriethyloxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, or γ-ureopropyltriethoxysilane.

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