A fluorescent composition for full-spectrum LEDs and a preparation method thereof

Abstract

The present application provides a fluorescent composition for full-spectrum LEDs and a preparation method thereof. The composition consists of highly thermally conductive modified silica gel, modified fluorescent powder, polyvinyl alcohol, tetrahydrofuran, and deionized water. The highly thermally conductive modified silica gel resin is boron nitride-modified polydimethylsiloxane, and the modified fluorescent powder is graphene quantum dot-calcium titanate modified lanthanide fluorescent powder. Through the cooperation of the highly thermally conductive modified silica gel resin, the modified fluorescent powder, and tetrahydrofuran, a heat dissipation network structure is formed inside the LED fluorescent composition. After being energized and excited, it spontaneously dissipates heat, reduces the working temperature of the LED, ensures the light efficiency of the LED, prevents spectral shift, extends the service life, and has the advantages of convenient use and easy popularization and implementation.

Description

Technical Field

[0001] The present invention belongs to the field of LEDs, and particularly relates to a fluorescent composition for full-spectrum LEDs and a preparation method thereof. Background Art

[0002] In the prior art, LED is the abbreviation of light-emitting diode, which has the advantages of low-voltage driving, all-solid state, low power consumption, long-term reliability, pollution-free, and energy conversion. It is widely used in various fields. The existing LED fluorescent coatings are often composed of multiple layers of materials to excite fluorescent substances. During the process of converting electrical energy into light energy by the fluorescent substances, a large amount of heat is generated. The existing LED fluorescent coatings generally have a low thermal conductivity and poor heat dissipation. After long-term use, the light efficiency of the LED will decrease, the spectrum will shift, and the service life will be greatly shortened. Therefore, improvements are urgently needed. Summary of the Invention

[0003] The first object of the present invention is to solve the technical problems in the prior art that the heat dissipation of the LED fluorescent coating is poor, a large amount of heat is generated during the light-emitting process, resulting in a decrease in the light efficiency of the LED, a spectral shift, and a shortened service life, and to propose a fluorescent composition for full-spectrum LEDs.

[0004] Another object of the present invention is to propose a fluorescent composition for full-spectrum LEDs and a preparation method thereof.

[0005] To achieve the first object, the present application adopts the following scheme:

[0006] A fluorescent composition for full-spectrum LEDs, by weight, comprises the following components:

[0007]

[0008] The highly thermally conductive modified silica gel is boron nitride-modified polydimethylsiloxane,

[0009] The modified fluorescent powder is graphene quantum dot-calcium titanate modified lanthanide fluorescent powder;

[0010] The wavelength range of the light emitted by the fluorescent powder in the excited state is 490-660 nm.

[0011] In the actual implementation process, boron nitride-modified polydimethylsiloxane has the following advantages: First, boron nitride has excellent thermal conductivity, and modifying it into polydimethylsiloxane can significantly improve the thermal conductivity of the material;

[0012] Second, boron nitride has excellent thermal conductivity, and modifying it into polydimethylsiloxane can significantly improve the thermal conductivity of the material, that is, the heat generated by the LED chip can be conducted to the surface of the material faster, improving the heat dissipation efficiency;

[0013] Thirdly, boron nitride has excellent plasticity and can be effectively dispersed and crosslinked with silica gel to form a heat dissipation network structure inside the silica gel, increasing the heat dissipation area and improving the heat dissipation efficiency.

[0014] Preferably, the preparation method of the high thermal conductivity modified silica gel includes the following steps:

[0015] Step 101. Put polydimethylsiloxane and acetamide into a stirring kettle according to a mass ratio of 10 - 15:1, and stir and activate for 10 - 30 minutes at a water bath temperature of 30 - 50°C and 200 - 500 rpm to obtain activated silica gel.

[0016] Step 102. After heating the activated silica gel obtained in Step 101 to 80 - 100°C in a water bath, put the activated silica gel and boron nitride into a stirring kettle according to a mass ratio of 4 - 8:1, and add tetrahydrofuran and ethylenediamine dropwise. Disperse for 30 - 50 minutes at 800 - 1200 rpm to obtain high thermal conductivity silica gel.

[0017] Preferably, the boron nitride in Step 102 has a sphericity of 85 - 90% and a particle size of 20 - 50 nm of spherical boron nitride.

[0018] In the actual implementation process, spheroidizing boron nitride has the following advantages:

[0019] Firstly, after boron nitride is spheroidized, the specific surface area increases significantly, but the dispersion performance with silica gel will not decrease significantly. Compared with other forms of boron nitride, the thermal conductivity is lower and the heat dissipation ability is stronger.

[0020] Secondly, there are microscopic protrusions and depressions on the surface of spherical boron nitride, which can provide more connection sites for the silica gel matrix, increase the heat conduction path, improve the degree of disorder of the heat dissipation network structure, increase the heat dissipation speed, and further improve the heat dissipation performance of the LED.

[0021] Preferably, the preparation method of the spherical boron nitride includes the following steps:

[0022] Step 201. Put a mixture of boron nitride, carbamide and silane coupling agent into a ball mill, and ball mill for 24 - 48 hours at room temperature and 500 - 600 rpm to obtain a boron nitride slurry.

[0023] Step 202. Put the boron nitride slurry prepared in Step 201 into an atomizing sprayer, and spray the boron nitride slurry into a drying chamber to obtain rough spherical boron nitride.

[0024] Step 203. Put the rough spherical boron nitride obtained in Step 202 into a crucible, and sinter for 3 - 5 hours under a vacuum of 0.01 Mpa and a temperature of 1900 - 2000°C to obtain spherical boron nitride.

[0025] Preferably, in the step 201, the mass ratio of boron nitride, carbamide and silane coupling agent is 10-15: 2-4: 1-2.

[0026] Preferably, the preparation method of the modified phosphor comprises the following steps:

[0027] Step 301. Put the lanthanide phosphor and nano-perovskite powder into a disperser, after dispersing evenly, transfer them to a muffle furnace, gradually heat up to 300-800 °C and calcine for 1-3 h, then heat up to 1000-1300 °C and calcine for 3-6 h to obtain a modified phosphor precursor.

[0028] Step 302. After cooling the modified phosphor precursor prepared in step 301 to 500-650 °C, spray graphene quantum dots into the muffle furnace, vibrate the modified phosphor precursor, heat up to 800-1200 °C and calcine for 3-5 h to obtain the modified phosphor.

[0029] Preferably, the lanthanide phosphor in the step 301 is a mixture of lanthanum oxide, dysprosium oxide, europium oxide and praseodymium oxide in a mass ratio of 5-8: 1-3: 1: 2.

[0030] Preferably, the preparation method of the graphene quantum dots in the step 302 comprises the following steps:

[0031] Step 401. Put chitosan, ethanolamine, hydrochloric acid and deionized water into an ultrasonic stirring kettle in sequence, and stir for 30-80 min at room temperature and 1800-2300 rpm to obtain a graphene precursor.

[0032] Step 402. Put the graphene precursor obtained in step 401 into a high-pressure sealed reaction kettle, and react for 5 h under the conditions of 115-130 °C and 300-600 atm to obtain a crude graphene quantum dot extraction solution.

[0033] Step 403. Dialyze the crude graphene quantum dot extraction solution obtained in step 402 with a dialysis membrane until it is clear, and then freeze-dry to obtain graphene quantum dots.

[0034] Preferably, the pore size of the dialysis membrane in the step 403 is 50-200 nm.

[0035] In the actual implementation process, the structure of graphene is a two-dimensional lattice composed of carbon atoms, with a hexagonal honeycomb arrangement, having extremely high thermal conductivity and stability. After restricting its particle size to a specific range, its crystal phase gap fits with that of the lanthanide phosphor. During the calcination process, graphene can combine with the lanthanide phosphor to form a graphene-phosphor system.

[0036] The graphene-modified lanthanide phosphor has the following advantages:

[0037] First, graphene has excellent optoelectronic properties and can absorb and emit light. Lanthanide phosphors also have good optoelectronic properties, can absorb light of a certain wavelength, and emit light of other wavelengths. This enables graphene and lanthanide phosphors to cooperate with each other to achieve light conversion and regulation.

[0038] Second, graphene has excellent interfacial affinity and can form good interfacial bonding with other materials. Lanthanide phosphors also have good interfacial affinity and can form stable interfacial bonding with other materials. This enables graphene and lanthanide phosphors to form a stable interfacial structure in composite materials or devices.

[0039] Nano perovskite powder has excellent optoelectronic properties and can absorb and emit light in the visible light range. Moreover, it has a large specific surface area, can provide more active sites, and thus improve the efficiency of photocatalytic reactions.

[0040] The nano perovskite powder modified phosphor has the following advantages:

[0041] First, the nano perovskite modified phosphor can be prepared into a very thin film and can be evenly covered on the LED chip. This nano perovskite modified phosphor in the form of a film can fill tiny gaps and uneven surfaces, improve the continuity of heat conduction, reduce thermal resistance, and further improve the heat dissipation effect;

[0042] Second, the nano perovskite modified phosphor has a high thermal conductivity and can effectively conduct the heat generated by the LED chip, improving the heat dissipation effect.

[0043] To achieve the second objective, the present application adopts the following solution;

[0044] A method for preparing a fluorescent composition for full-spectrum LEDs, comprising the following steps:

[0045] Step 501. Put the highly thermally conductive modified silica gel and the modified phosphor into a high-speed disperser. At room temperature, under the conditions of 2000 - 2500 rpm, gradually add an appropriate amount of deionized water and tetrahydrofuran dropwise, and disperse for 50 - 80 min to obtain Component A;

[0046] Step 502. Put the Component A obtained in Step 501, the remaining deionized water, the remaining tetrahydrofuran, and polyvinyl alcohol into the high-speed disperser in sequence. Under the conditions of heating the water bath to 56 °C and 1500 - 1800 rpm, disperse for 20 - 50 min to obtain the LED fluorescent composition.

[0047] The present invention has the following advantages compared with the prior art:

[0048] 1. The present application provides a fluorescent composition for full-spectrum LEDs, which is composed of highly thermally conductive modified silica gel, modified fluorescent powder, polyvinyl alcohol, tetrahydrofuran, and deionized water. The highly thermally conductive modified silica gel resin is boron nitride-modified polydimethylsiloxane, and the modified fluorescent powder is graphene quantum dot-calcium titanate modified lanthanide fluorescent powder. Through the cooperation of the highly thermally conductive modified silica gel resin, the modified fluorescent powder, and tetrahydrofuran, a heat dissipation network structure is formed inside the LED fluorescent composition. After being energized and excited, it spontaneously dissipates heat, reduces the working temperature of the LED, ensures the luminous efficiency of the LED, prevents spectral shift, extends the service life, and has the advantages of convenient use and easy popularization and implementation.

[0049] 2. The present application provides a preparation method for a fluorescent composition for full-spectrum LEDs. By gradually adding a mixture of tetrahydrofuran and deionized water and dispersing it, the interfacial properties of the fluorescent composition are significantly improved, and the heat dissipation ability is enhanced. It has the advantages of simple operation and convenient implementation. Specific Embodiments

[0050] The present invention will be further described below with reference to Table 1, Specific Examples 1-3, and Comparative Examples 1-3:

[0051] Example 1.

[0052] (1) The preparation method of highly thermally conductive modified silica gel includes the following steps:

[0053] Step 101. Put polydimethylsiloxane and acetamide into a stirring kettle at a mass ratio of 10.5:1, and stir and activate for 11 minutes at a water bath temperature of 35.2 °C and 250 rpm to obtain activated silica gel.

[0054] Step 102. After heating the activated silica gel obtained in Step 101 to 85 °C in a water bath, put the activated silica gel and boron nitride into a stirring kettle at a mass ratio of 4.5:1, and gradually dropwise add a 1:1 mixture of tetrahydrofuran and ethylenediamine accounting for 18% of the total volume, and disperse for 31 minutes at 877 rpm to obtain highly thermally conductive silica gel.

[0055] The boron nitride in Step 102 has a sphericity of 88% and a particle size of 29 nm spherical boron nitride.

[0056] (2) The preparation method of spherical boron nitride includes the following steps:

[0057] Step 201. Put boron nitride, carbamide, and silane coupling agent into a ball mill at a mass ratio of 8:4:1, and ball mill for 25 hours at room temperature and 541 rpm to obtain a boron nitride slurry.

[0058] Step 202. The boron nitride slurry prepared in Step 201 is put into an atomizing sprayer, and the boron nitride slurry is sprayed into a drying chamber at 1200 °C to obtain coarsely spheroidized boron nitride;

[0059] Step 203. The coarsely spheroidized boron nitride obtained in Step 202 is put into a crucible, and sintered for 3 h under the conditions of a vacuum degree of 0.01 Mpa and a temperature of 1900 °C to obtain spheroidized boron nitride.

[0060] In the said Step 201, the mass ratio of boron nitride, carbamide and silane coupling agent is 11:2:1.

[0061] (3) Preparation method of modified phosphor, including the following steps:

[0062] Step 301. Put lanthanide phosphor and nano-perovskite powder into a disperser, after dispersing evenly, transfer to a muffle furnace, heat up to 350 °C at a heating rate of 10 °C / min and calcine for 1 h, then heat up to 1100 °C at a heating rate of 50 °C / min and calcine for 3.5 h to obtain a modified phosphor precursor;

[0063] Step 302. After the modified phosphor precursor prepared in Step 301 is cooled to 510 °C, spray graphene quantum dots into the muffle furnace, vibrate the modified phosphor precursor, heat up to 880 °C and calcine for 3.5 h to obtain the modified phosphor.

[0064] The lanthanide phosphor in the said Step 301 is a mixture of lanthanum oxide, dysprosium oxide, europium oxide and praseodymium oxide according to the mass ratio of 5.5:1.2:1:2.

[0065] (4) Preparation method of graphene quantum dots, including the following steps:

[0066] Step 401. Put chitosan, ethanolamine, hydrochloric acid and deionized water into an ultrasonic stirring kettle in sequence according to the mass ratio of 5:2:3:2, stir for 35 min at room temperature and 1850 rpm to obtain a graphene precursor;

[0067] Step 402. Put the graphene precursor obtained in Step 401 into a high-pressure closed reactor, react for 5 h under the conditions of 120 °C and 310 atm to obtain a crude graphene quantum dot extraction solution;

[0068] Step 403. Dialyze the crude graphene quantum dot extraction solution obtained in Step 402 with a dialysis membrane with a membrane pore size of 57 nm until it is clarified, and then freeze-dry to obtain graphene quantum dots.

[0069] (5) Preparation method of a fluorescent composition for full-spectrum LED, including the following steps:

[0070] Step 501. Put the highly thermally conductive modified silica gel and the modified fluorescent powder into a high-speed disperser according to the parts by mass shown in Table 1. At room temperature, under the condition of 2100 rpm, add an appropriate amount of deionized water and tetrahydrofuran drop by drop, and disperse for 50 min to obtain Component A;

[0071] Step 502. Put Component A obtained in Step 501, the remaining deionized water, the remaining tetrahydrofuran, and polyvinyl alcohol into a high-speed disperser according to the parts by mass shown in Table 1. Under the condition of heating the water bath to 56 °C and 1550 rpm, disperse for 2 min to obtain the LED fluorescent composition.

[0072] Example 2.

[0073] (1) Preparation method of highly thermally conductive modified silica gel, including the following steps:

[0074] Step 101. Put polydimethylsiloxane and acetamide into a stirring kettle according to a mass ratio of 13:1. Under the condition of a water bath temperature of 41 °C and 200 - 500 rpm, stir and activate for 22 min to obtain activated silica gel;

[0075] Step 102. After heating the activated silica gel obtained in Step 101 to 85 °C in a water bath, put the activated silica gel and boron nitride into a stirring kettle according to a mass ratio of 4.5:1. Dropwise add a 1:1 mixture of tetrahydrofuran and ethylenediamine accounting for 18% of the total volume, and disperse for 44 min under the condition of 1050 rpm to obtain highly thermally conductive silica gel.

[0076] The boron nitride in Step 102 has a sphericity of 86% and a particle size of 33 nm of spheroidized boron nitride.

[0077] (2) Preparation method of spheroidized boron nitride, including the following steps:

[0078] Step 201. Put boron nitride, carbamide, and silane coupling agent into a ball mill according to a mass ratio of 10:4:1. At room temperature, under the condition of 550 rpm, ball mill for 32 h to obtain a boron nitride slurry;

[0079] Step 202. Put the boron nitride slurry prepared in Step 201 into an atomizing sprayer, and spray the boron nitride slurry into a drying chamber at 1200 °C to obtain coarse spheroidized boron nitride;

[0080] Step 203. Put the coarse spheroidized boron nitride obtained in Step 202 into a crucible, and sinter at a vacuum degree of 0.01 Mpa and a temperature of 1950 °C for 4 h to obtain spheroidized boron nitride.

[0081] In Step 201, the mass ratio of boron nitride, carbamide, and silane coupling agent is 13:3:2.

[0082] (3) Preparation method of modified phosphor, comprising the following steps:

[0083] Step 301. Put lanthanide phosphor and nano-perovskite powder into a disperser, after dispersing evenly, transfer them to a muffle furnace, heat up to 500 °C at a heating rate of 10 °C / min and calcine for 2 h, then heat up to 1200 °C at a heating rate of 50 °C / min and calcine for 4 h to obtain a modified phosphor precursor;

[0084] Step 302. After cooling the modified phosphor precursor prepared in Step 301 to 550 °C, spray graphene quantum dots into the muffle furnace, vibrate the modified phosphor precursor, heat up to 1043 °C and calcine for 4 h to obtain the modified phosphor.

[0085] The lanthanide phosphor in Step 301 is a mixture of lanthanum oxide, dysprosium oxide, europium oxide and praseodymium oxide in a mass ratio of 6:2:1:2.

[0086] (4) Preparation method of graphene quantum dots, comprising the following steps:

[0087] Step 401. Put chitosan, ethanolamine, hydrochloric acid and deionized water into an ultrasonic stirring kettle in sequence according to a mass ratio of 5:2:3:2, stir for 55 min at room temperature and 2150 rpm to obtain a graphene precursor;

[0088] Step 402. Put the graphene precursor obtained in Step 401 into a high-pressure sealed reaction kettle, react for 5 h under the conditions of 120 °C and 400 atm to obtain a crude graphene quantum dot extraction solution;

[0089] Step 403. Dialyze the crude graphene quantum dot extraction solution obtained in Step 402 with a dialysis membrane with a membrane pore size of 77 nm until it is clear, and then freeze-dry to obtain graphene quantum dots.

[0090] (5) Preparation method of a fluorescent composition for full-spectrum LED, comprising the following steps:

[0091] Step 501. Put high thermal conductivity modified silica gel and modified phosphor into a high-speed disperser according to the mass fractions shown in Table 1, disperse for 67 min at room temperature and 2200 rpm under the condition of dropping appropriate amount of deionized water and tetrahydrofuran drop by drop to obtain Component A;

[0092] Step 502. Put Component A obtained in Step 501, the remaining deionized water, the remaining tetrahydrofuran and polyvinyl alcohol into a high-speed disperser in sequence according to the mass fractions shown in Table 1, disperse for 37 min under the conditions of heating the water bath to 56 °C and 1650 rpm to obtain the LED fluorescent composition.

[0093] Example 3.

[0094] (1) Preparation method of high thermal conductivity modified silica gel, comprising the following steps:

[0095] Step 101. Put polydimethylsiloxane and acetamide into a stirring kettle according to a mass ratio of 15:1, and stir and activate for 30 min at a water bath temperature of 50 °C and 500 rpm to obtain activated silica gel;

[0096] Step 102. After heating the activated silica gel obtained in Step 101 to 85 °C in a water bath, put the activated silica gel and boron nitride into a stirring kettle according to a mass ratio of 4.5:1, and dropwise add a 1:1 mixture of tetrahydrofuran and ethylenediamine accounting for 18% of the total volume, and disperse for 45 min at 1150 rpm to obtain high thermal conductivity silica gel.

[0097] The boron nitride in Step 102 has a sphericity of 88% and is spherical boron nitride with a particle size of 48 nm.

[0098] (2) Preparation method of spherical boron nitride, comprising the following steps:

[0099] Step 201. Put boron nitride, carbamide and silane coupling agent into a ball mill according to a mass ratio of 12:4:1, and ball mill for 48 h at room temperature and 580 rpm to obtain a boron nitride slurry;

[0100] Step 202. Put the boron nitride slurry prepared in Step 201 into an atomizing sprayer, and spray the boron nitride slurry into a drying chamber at 1200 °C to obtain coarse spherical boron nitride;

[0101] Step 203. Put the coarse spherical boron nitride obtained in Step 202 into a crucible, and sinter for 5 h at a vacuum degree of 0.01 Mpa and a temperature of 2000 °C to obtain spherical boron nitride.

[0102] In Step 201, the mass ratio of boron nitride, carbamide and silane coupling agent is 15:4:1.

[0103] (3) Preparation method of modified fluorescent powder, comprising the following steps:

[0104] Step 301. Put lanthanide fluorescent powder and nano-perovskite powder into a disperser, disperse evenly, then transfer to a muffle furnace, heat at a heating rate of 10 °C / min to 780 °C and calcine for 3 h, and then heat at a heating rate of 50 °C / min to 1290 °C and calcine for 6 h to obtain a modified fluorescent powder precursor;

[0105] Step 302. After cooling the modified phosphor precursor prepared in Step 301 to 650 °C, spray graphene quantum dots into the muffle furnace, vibrate the modified phosphor precursor, heat it to 1160 °C, and calcine for 5 h to obtain the modified phosphor.

[0106] The lanthanide phosphor in Step 301 is a mixture of lanthanum oxide, dysprosium oxide, europium oxide, and praseodymium oxide in a mass ratio of 8:3:1:2.

[0107] (4) The preparation method of graphene quantum dots includes the following steps:

[0108] Step 401. Put chitosan, ethanolamine, hydrochloric acid, and deionized water into the ultrasonic stirring kettle in sequence according to the mass ratio of 5:2:3:2. Stir for 80 min at room temperature and 2300 rpm to obtain the graphene precursor.

[0109] Step 402. Put the graphene precursor obtained in Step 401 into a high-pressure sealed reaction kettle, react for 5 h at 130 °C and 600 atm to obtain the crude graphene quantum dot extraction solution.

[0110] Step 403. Dialyze the crude graphene quantum dot extraction solution obtained in Step 402 with a dialysis membrane with a membrane pore size of 188 nm until it is clear, and then freeze-dry to obtain graphene quantum dots.

[0111] (5) The preparation method of a full-spectrum LED fluorescent composition includes the following steps:

[0112] Step 501. Put the high thermal conductivity modified silica gel and the modified phosphor into a high-speed disperser according to the mass parts shown in Table 1. Disperse for 80 min at room temperature, 2500 rpm, and dropwise add an appropriate amount of deionized water and tetrahydrofuran to obtain Component A.

[0113] Step 502. Put Component A obtained in Step 501, the remaining deionized water, the remaining tetrahydrofuran, and polyvinyl alcohol into the high-speed disperser in sequence. Disperse for 50 min at a water bath temperature of 56 °C and 1800 rpm to obtain the LED fluorescent composition.

[0114] Comparative Example 1.

[0115] Replace the high thermal conductivity modified silica gel in Example 3 with single polydimethylsiloxane, and keep the other components unchanged;

[0116] Comparative Example 2. Replace the modified phosphor in Example 3 with single lanthanum oxide phosphor;

[0117] Table 1 Composition table of each component in Examples 1-3 and Comparative Examples 1-2 by weight parts

[0118]

[0119]

[0120] Examples 1-3 and Comparative Examples 1-2 were tested for luminous efficiency using a luminous flux measurement system at a working temperature of 25 °C and a color temperature of 5000 K. The color chromaticity uniformity was detected using a colorimeter (CS-100A) and evaluated by the nine-point method. The color chromaticity uniformity was evaluated based on the magnitude of the chromaticity difference between the nine points, and was divided into four grades: poor, fair, good, and excellent. Under the conditions of a fixed current (500 mA) and voltage (3 V), the change trend of the luminous flux of the LED was observed, and the time stage when the luminous flux began to decrease significantly was recorded to detect the service life of the LED fluorescent coating. In addition, under an independent temperature environment of 25 °C, the temperature of the LED fluorescent coating was monitored after working for 1 h, 24 h, 180 h, and 240 h under a fixed current and voltage to evaluate the overall heat dissipation situation.

[0121] Table 2 Test results of Examples 1-3 and Comparative Examples 1-2:

[0122]

[0123] As can be seen from Table 2 above, the present application provides a fluorescent composition for full-spectrum LEDs, which is composed of highly thermally conductive modified silica gel, modified phosphor, polyvinyl alcohol, tetrahydrofuran, and deionized water. The highly thermally conductive modified silica gel resin is boron nitride-modified polydimethylsiloxane, and the modified phosphor is graphene quantum dot-calcium titanate modified lanthanide phosphor. Through the cooperation of the highly thermally conductive modified silica gel resin, the modified phosphor, and tetrahydrofuran, a heat dissipation network structure is formed inside the LED fluorescent composition. After being excited by electricity, it spontaneously dissipates heat, reduces the working temperature of the LED, ensures the luminous efficiency of the LED, prevents the spectrum from shifting, extends the service life, and has the advantages of convenient use and easy popularization and implementation.

[0124] In the actual implementation process, boron nitride-modified polydimethylsiloxane has the following advantages: First, boron nitride has excellent thermal conductivity, and modifying it into polydimethylsiloxane can significantly improve the thermal conductivity of the material;

[0125] Second, boron nitride has excellent thermal conductivity, and modifying it into polydimethylsiloxane can significantly improve the thermal conductivity of the material, that is, the heat generated by the LED chip can be conducted to the material surface faster, improving the heat dissipation efficiency;

[0126] Third, boron nitride has excellent plasticity, can be effectively dispersed and crosslinked with silica gel, forms a heat dissipation network structure inside the silica gel, increases the heat dissipation area, and improves the heat dissipation efficiency.

[0127] After being replaced with conventional silicone, there is no heat dissipation network structure inside the silicone. The heat accumulation rate of the LED increases, the heat dissipation performance is poor, and the service life of the LED is reduced.

[0128] In the actual implementation process, the structure of graphene is a two-dimensional lattice composed of carbon atoms, with a hexagonal honeycomb arrangement, extremely high thermal conductivity, and stability. After restricting its particle size to a specific range, its crystal phase gap fits well with that of lanthanide phosphors. During the calcination process, graphene can combine with lanthanide phosphors to form a graphene-phosphor system.

[0129] Graphene-modified lanthanide phosphors have the following advantages:

[0130] First, graphene has excellent optoelectronic properties and can absorb and emit light. Lanthanide phosphors also have good optoelectronic properties and can absorb light of a certain wavelength and emit light of other wavelengths. This enables graphene and lanthanide phosphors to cooperate with each other to achieve light conversion and regulation.

[0131] Second, graphene has excellent interfacial affinity and can form good interfacial bonding with other materials. Lanthanide phosphors also have good interfacial affinity and can form stable interfacial bonding with other materials. This allows graphene and lanthanide phosphors to form a stable interfacial structure in composite materials or devices.

[0132] Nano-perovskite powder has excellent optoelectronic properties and can absorb and emit light in the visible light range. Moreover, it has a large specific surface area, which can provide more active sites, thereby improving the efficiency of the photocatalytic reaction.

[0133] Nano-perovskite powder-modified phosphors have the following advantages:

[0134] First, nano-perovskite-modified phosphors can be prepared into very thin films and can be evenly coated on the LED chip. This thin film form of nano-perovskite-modified phosphors can fill tiny gaps and uneven surfaces, improve the continuity of heat conduction, reduce thermal resistance, and further enhance the heat dissipation effect;

[0135] Second, nano-perovskite-modified phosphors have a high thermal conductivity and can effectively conduct the heat generated by the LED chip, improving the heat dissipation effect.

[0136] After being replaced with unmodified lanthanide phosphors, there are no heat dissipation units in the crystal phase and they cannot cooperate with the heat dissipation network structure in the matrix to improve the heat dissipation of the LED, reducing the service life of the LED.

[0137] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fluorescent composition for full-spectrum LEDs, characterized in that, By weight parts, it includes the following components: 20 - 32 parts of highly thermally conductive modified silica gel; 8 - 15 parts of modified phosphor powder; 2 - 10 parts of polyvinyl alcohol; 2 - 10 parts of tetrahydrofuran; 5 - 15 parts of deionized water; The highly thermally conductive modified silica gel is boron nitride modified polydimethylsiloxane, The modified phosphor powder is graphene quantum dot - perovskite modified lanthanide phosphor powder; The wavelength range of the light emitted by the phosphor powder in the excited state is 490 - 660nm; The preparation method of the highly thermally conductive modified silica gel includes the following steps: Step 101. Put polydimethylsiloxane and acetamide into a stirring kettle according to a mass ratio of 10 - 15:1, and stir and activate for 10 - 30 min under the conditions of a water bath temperature of 30 - 50°C and 200 - 500 rpm to obtain activated silica gel; Step 102. After heating the activated silica gel obtained in Step 101 to 80 - 100°C in a water bath, put the activated silica gel and boron nitride into a stirring kettle according to a mass ratio of 4 - 8:1, and add tetrahydrofuran and ethylenediamine dropwise, and disperse for 30 - 50 min under the condition of 800 - 1200 rpm to obtain highly thermally conductive silica gel; The preparation method of the modified phosphor powder includes the following steps: Step 301. Put lanthanide phosphor powder and nano - perovskite powder into a disperser, after dispersing evenly, transfer it to a muffle furnace, gradually heat it to 300 - 800°C and calcine for 1 - 3 h, then heat it to 1000 - 1300°C and calcine for 3 - 6 h to obtain a modified phosphor powder precursor; Step 302. After cooling the modified phosphor powder precursor prepared in Step 301 to 500 - 650°C, spray graphene quantum dots into the muffle furnace, vibrate the modified phosphor powder precursor, heat it to 800 - 1200°C and calcine for 3 - 5 h to obtain the modified phosphor powder.

2. The fluorescent composition for full-spectrum LEDs according to claim 1, wherein, The boron nitride in Step 102 has a sphericity of 85 - 90% and a particle size of 20 - 50nm spherical boron nitride.

3. The fluorescent composition for full-spectrum LEDs according to claim 2, wherein, The preparation method of the spherical boron nitride includes the following steps: Step 201. Put a mixture of boron nitride, carbamide and silane coupling agent into a ball mill, and ball mill for 24 - 48 h at room temperature under the condition of 500 - 600 rpm to obtain a boron nitride slurry; Step 202. Put the boron nitride slurry prepared in Step 201 into an atomizing sprayer, and spray the boron nitride slurry into a drying chamber to obtain rough spherical boron nitride; Step 203. Put the rough spherical boron nitride obtained in Step 202 into a crucible, and sinter for 3 - 5 h under the conditions of a vacuum degree of 0.01 Mpa and a temperature of 1900 - 2000°C to obtain spherical boron nitride.

4. A fluorescent composition for full-spectrum LEDs according to claim 3, characterized in that, In Step 201, the mass ratio of boron nitride, carbamide and silane coupling agent is 10 - 15:2 - 4:1 - 2.

5. A fluorescent composition for full-spectrum LEDs according to claim 1, characterized in that, The lanthanide phosphor powder in Step 301 is a mixture of lanthanum oxide, dysprosium oxide, europium oxide and praseodymium oxide according to a mass ratio of 5 - 8:1 - 3:1:

2.

6. The fluorescent composition for full-spectrum LEDs according to claim 1, wherein, The preparation method of the graphene quantum dots in Step 302 includes the following steps: Step 401. Chitosan, ethanolamine, hydrochloric acid and deionized water are sequentially added into an ultrasonic stirring kettle. Under the conditions of room temperature and 1800 - 2300 rpm, after stirring for 30 - 80 min, a graphene precursor is obtained. Step 402. The graphene precursor obtained in Step 401 is added into a high-pressure sealed reaction kettle. Under the conditions of 115 - 130 °C and 300 - 600 atm, after reacting for 5 h, a crude graphene quantum dot extraction solution is obtained. Step 403. The crude graphene quantum dot extraction solution obtained in Step 402 is dialyzed using a dialysis membrane until it is clear, and then freeze-dried to obtain graphene quantum dots.

7. A fluorescent composition for full-spectrum LEDs according to claim 6, characterized in that, The pore size of the dialysis membrane in Step 403 is 50 - 200 nm.

8. The preparation method of a fluorescent composition for a full-spectrum LED according to any one of claims 1-7, characterized in that, It includes the following steps: Step 501. High thermal conductivity modified silica gel and modified phosphor are added into a high-speed disperser. At room temperature, under the conditions of 2000 - 2500 rpm and dropwise addition of an appropriate amount of deionized water and tetrahydrofuran, after dispersing for 50 - 80 min, component A is obtained. Step 502. Component A obtained in Step 501, the remaining deionized water, the remaining tetrahydrofuran, and polyvinyl alcohol are sequentially added into a high-speed disperser. Under the conditions of water bath heating to 56 °C and 1500 - 1800 rpm, after dispersing for 20 - 50 min, an LED fluorescent composition is obtained.

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