High color rendering index and high light efficiency fluorescent conversion composite material for laser illumination and preparation method thereof

Abstract

The application discloses a high-color-rendering-index and high-luminous-efficiency fluorescent conversion composite material for laser lighting and a preparation method thereof. The fluorescent conversion composite material is composed of a lens-shaped fluorescent ceramic and a fluorescent silica gel layer coated on the surface of the fluorescent ceramic. The fluorescent ceramic emits yellow-green light under excitation of blue excitation light. The fluorescent silica gel layer emits red light under excitation of the blue excitation light. The lens-shaped fluorescent ceramic is prepared by using a gel injection molding method, and then a red fluorescent silica gel layer is coated on the surface of the lens-shaped fluorescent ceramic. After drying, the fluorescent conversion composite material is obtained. The composite fluorescent material prepared by the application realizes high-brightness white light emission under excitation of a 455nm blue light LD chip, has a luminous efficiency of 190-260lm / W, a color rendering index of 90-96, and is simple to prepare and easy to industrialize.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser lighting, and particularly relates to a high-color-rendering-index and high-luminous-efficiency fluorescent conversion composite material for laser lighting and a preparation method thereof. BACKGROUND

[0002] As a new type of solid-state lighting, laser lighting is expected to become the next generation of general lighting due to its high luminous flux, high brightness, small size and other outstanding advantages. As an extremely important fluorescent conversion material in laser lighting, fluorescent ceramic has become the best and most application potential fluorescent material for high-power solid-state lighting due to its high thermal stability and thermal conductivity, high quantum efficiency, and easy-to-control microstructure. For common Ce 3+ doped garnet-based fluorescent ceramic, its color rendering index is low (CRI ~ 60) due to the lack of effective red light components, and it has many disadvantages such as emission color shift and reduced human eye comfort.

[0003] At present, a large number of literatures have reported modification treatment of fluorescent ceramic in order to realize the regulation of the light emission behavior of fluorescent ceramic. The literature (Thermostability and reliability properties studies of transparent Ce:GdYAG ceramic by Gd substitution for white LEDs. Optical Materials, 2019, 94, 172-181) reports that by co-doping Gd 3+ ions can cause red shift of the emission peak of Ce 3+ ions, but the moving range is very limited, and the color temperature improvement effect is not obvious. The literature (Composite structure Cr:YAG / Ce:YAG and (Ce,Cr):YAG / Ce:YAG transparent ceramics with high color rendering index for white LEDs / LDs. Ceram. Int, 2021, 47(8), 11415-11422) reports that YAG:Ce, Cr: / YAG:Ce double-layer composite phosphor ceramic is prepared by dry pressing and vacuum sintering, and the color rendering index is improved under blue light excitation. However, due to the existence of serious interface effect, the luminous efficiency is greatly limited, and the light quantity of the device is seriously lost. CN114497326A discloses a fluorescent conversion composite layer, a preparation method and a white light emitting device. By layering the fluorescent ceramic layer and the fluorescent glass layer, white light emission is realized, and a high color rendering index is obtained. However, its luminous efficiency is low, and the preparation cost is higher and the process is more complex. SUMMARY

[0004] One of the purposes of the present application is to provide a high color rendering index and high luminous efficiency fluorescent conversion composite material for laser lighting, which has the advantages of high color rendering index and high luminous efficiency as a luminescent material.

[0005] The second purpose of the present application is to provide a preparation method of the high color rendering index and high luminous efficiency fluorescent conversion composite material for laser lighting, which is easy to realize industrial production.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0007] In the first aspect, the present application provides a high color rendering index and high luminous efficiency fluorescent conversion composite material for laser lighting, which is composed of a lens-shaped fluorescent ceramic and a fluorescent silica gel layer coated on the surface of the fluorescent ceramic, the fluorescent ceramic emits yellow-green light under excitation of blue excitation light, and the fluorescent silica gel layer emits red light under excitation of the blue excitation light.

[0008] Among them, the parameters of the fluorescent ceramic are: curvature 0.2-0.9, bottom diameter 5-20 mm, height 5-20 mm; the thickness of the fluorescent silica gel layer is 0.1-2 mm.

[0009] Preferably, the composition of the fluorescent ceramic is (RE 1-x Ce x )3Al5O 12 , wherein RE is one or more of Y, Lu, Ga, Gd, and Tb, x is the mole percentage of Ce-doped RE sites, and 0.0001≤x≤0.005.

[0010] In the second aspect, the present application also provides a preparation method of the above-mentioned high color rendering index and high luminous efficiency fluorescent conversion composite material for laser lighting, which specifically includes the following steps:

[0011] Step one: preparing a lens-shaped fluorescent ceramic by using a gel casting method;

[0012] Step two: preparing a red fluorescent silica gel layer:

[0013] (1) uniformly mixing an organic silica gel and a red fluorescent powder, and preparing a mixed solution after vacuum degassing;

[0014] (2) uniformly applying the obtained mixed solution on the surface of the lens-shaped fluorescent ceramic, and drying in a drying oven for 0.5-10 h to obtain a fluorescent conversion composite material.

[0015] Preferably, the specific steps of preparing the lens-shaped fluorescent ceramic by using the gel casting method are as follows:

[0016] (1.1) raw material powder preparation: preparing raw material powders according to the components (RE1-x Ce x )3Al5O 12 The stoichiometric ratio of each element in the raw material powder is weighed, wherein RE is one or more of Y, Lu, Ga, Gd, and Tb, 0.0001≤x≤0.005; a dispersant PEI, a sintering aid MgO, and TEOS, anhydrous ethanol are added, and the mixed slurry is obtained by ball milling; the slurry is dried, sieved, and calcined to obtain the fluorescent ceramic powder;

[0017] (1.2) Preparation of the injection molding slurry: the fluorescent ceramic powder prepared in step (1.1) is added with a dispersant acrylamide, a pH regulator tetramethylammonium hydroxide, a monomer acrylamide, a crosslinking agent N-N'methylene bisacrylamide, and pure water, and the slurry is filtered after ball milling, and a catalyst tetramethyl ethylenediamine is added after vacuum degassing, and the mixture is uniformly mixed;

[0018] (1.3) Gel injection molding: the mixed slurry is poured into a customized mold, and heat initiation is performed at 50-80℃ to solidify and form;

[0019] (1.4) Drying and glue removal: the solidified body is dried in a constant temperature and humidity box for 12-36h, and then placed in a muffle furnace for glue removal to obtain the fluorescent ceramic body;

[0020] (1.5) The ceramic body is placed in a vacuum sintering furnace for sintering to obtain a lens-shaped fluorescent ceramic, which is then air annealed in a muffle furnace, and the lens-shaped fluorescent ceramic is obtained after polishing the ceramic surface;

[0021] Preferably, in step (1.1), the dispersant is added in an amount of 0.1-0.5wt% of the total mass of the raw materials; the MgO is added in an amount of 0.1-0.6wt% of the total mass of the raw materials; the TEOS is added in an amount of 0.3-0.5wt% of the total mass of the raw materials; the ball milling speed is 160-220r / min, and the ball milling time is 12-24h; the drying temperature is 50-80℃, and the drying time is 6-24h; the mesh size of the sieve is 80-300 meshes; and the muffle calcination temperature is 800-1000℃.

[0022] Preferably, in step (1.2), the dispersant is added in an amount of 0.25-0.5wt% of the total mass of the raw materials, the pH regulator is added in an amount of 1-1.5wt% of the total mass of the raw materials, the monomer is added in an amount of 2-3wt% of the total mass of the raw materials, and the crosslinking agent is added in an amount of 0.2-0.3wt% of the total mass of the raw materials; the ball milling speed is 140-200r / min, and the ball milling time is 8-12h; and the solid content of the slurry is 40-60vol.%.

[0023] Preferably, the drying temperature in step (1.4) is 25-60℃, the drying humidity is 30%-80%, the glue exhausting temperature is 600-900℃, and the glue exhausting time is 24-72h.

[0024] Preferably, the vacuum sintering temperature in step (1.5) is 1740-1820℃, the holding time is 8-30h; the annealing temperature is 1400-1500℃, and the annealing time is 8-16h.

[0025] Preferably, the linear transmittance of the prepared fluorescent ceramic at 800nm is 60-80%.

[0026] Preferably, in step two (1), the red fluorescent powder is selected from at least one of (Sr,Ca)AlSiN3:Eu 2+ , CaAlSiN3:Eu 2+ , K2GeF6:Mn 4+ , K2TiF6:Mn 4+ , K2SiF6:Mn 4+ , Y2O3:Eu 3+ , Sr2Si5N8:Eu 2+ , Ca[LiAl3N4]:Eu 2+ , Sr[LiAl3N4]:Eu 2+ , and Sr[Li2Al2O2N2]:Eu 2+ ; and the mass ratio of the silicone glue to the red fluorescent powder is 1:0.1-10.0.

[0027] Preferably, in step two (2), the drying temperature of the mixed solution is 50-150℃.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The prepared composite fluorescent material in the present application realizes high-brightness white light emission under the excitation of a 455nm blue light LD chip, with a luminous efficiency of 190-260lm / W and a color rendering index of 90-96.

[0030] (2) The fluorescent ceramic in the present application is designed in a lens shape, and the emission angle of the fluorescent light is flexibly controlled by adjusting the curvature of the lens ceramic, so that the light beam is shaped and the color uniformity of the fluorescent material is improved; compared with the traditional parallel structure, the lens-shaped fluorescent ceramic can effectively reduce the "total internal reflection effect" at the interface and improve the light extraction rate of the material, so that high-lumen efficiency and high-brightness light emitting performance are realized.

[0031] (3) The present invention adopts a scheme of coating red fluorescent silicone on the surface of fluorescent ceramic to obtain composite fluorescent conversion material, which can effectively adjust the correlated color temperature of fluorescent material, obtain a high color rendering index, and further improve the lighting quality.

[0032] (4) The present invention uses gel casting to prepare lens-shaped fluorescent ceramic blanks, which can effectively control the fine structure of the blanks without defects such as cracks and deformation, and at the same time realize mass production, which is conducive to the industrialization of the preparation of composite fluorescent ceramics. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure and luminescence of the composite fluorescent material of the present invention; in the figure, 1-fluorescent silicone layer; 2-fluorescent ceramic;

[0034] Figure 2 This is a flowchart of the preparation method for composite fluorescent ceramics.

[0035] Figure 3 The output power density in Example 1 is 29.3 W / mm². 2 The EL spectrum of the composite fluorescent material under blue light excitation.

[0036] Figure 4 The curve shows the change in luminescence efficiency of the composite fluorescent material under blue light excitation in Example 1. Detailed Implementation

[0037] The specific embodiments of the present invention will be briefly described below with reference to the accompanying drawings. Obviously, the following embodiments are merely some embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0038] Example 1

[0039] This embodiment provides a high color rendering index and high luminous efficiency fluorescence conversion composite material for laser illumination, such as... Figure 1 As shown, a lens-shaped 0.01 at.% Ce:LuAG fluorescent ceramic 2 and (Sr,Ca)AlSiN3:Eu coated on the fluorescent ceramic 2 are used. 2+ The fluorescent silicone layer 1 is composed of:

[0040] The fluorescent ceramic 2 emits green light when excited by blue excitation light, and the fluorescent silicone layer 1 emits red light when excited by blue excitation light. After the green and red light are refracted by the lens structure, the difference in the emission angle with the blue laser is reduced, resulting in a uniform white light spot. In addition, the lens structure enables the fluorescence confined inside the ceramic by total internal reflection to be emitted, thereby improving the light extraction rate and luminous efficiency of the fluorescent ceramic.

[0041] The final parameters of the lens-shaped fluorescent ceramic 2 are: curvature 0.5, bottom diameter 5 mm, height 5 mm; the thickness of the fluorescent silica gel layer 1 is 1 mm.

[0042] As shown in Figure 2 , the preparation method of the fluorescent conversion composite material comprises the following steps:

[0043] Step one: using gel casting method to prepare Ce: LuAG ceramic blank:

[0044] (1) Raw material powder preparation: 60 g of raw material powder is weighed according to the stoichiometric ratio of Lu 0.9999 Ce 0.0001 )3Al5O 12 , 0.06 g of PEI, 0.06 g of MgO and 0.18 g of TEOS, 80 mL of anhydrous ethanol, ball milling on a ball mill at 160 r / min for 12 h to obtain a mixed slurry; drying at 50℃ for 6h, sieving through an 80 mesh screen, and then calcining in a muffle furnace at 800℃ to obtain Ce: LuAG ceramic powder;

[0045] (2) Preparation of mold slurry: 0.15 g of acrylamide, 0.6 g of tetramethylammonium hydroxide, 1.2 g of acrylamide, 1.2 g of N-N' methylene bisacrylamide, 9.7 g of pure water are added to the Ce: LuAG ceramic powder prepared in step (1), and the slurry is filtered after ball milling at 140 r / min for 8 h, the solid content of the slurry is 40 vol.%, and 110 μL of tetramethyl ethylenediamine is added after vacuum degassing, and the mixture is uniformly mixed;

[0046] (3) Gel casting: pour the mixed slurry into a custom mold, heat initiate at 50℃, and solidify into a shape;

[0047] (4) Drying and degassing: the cured body is dried in a constant temperature and humidity box at 25℃ and 30% humidity for 12h, and then placed in a muffle furnace for degassing, the degassing temperature is 600℃, the degassing time is 24h, and the Ce: LuAG ceramic blank is obtained;

[0048] (5) The ceramic blank is placed in a vacuum sintering furnace for sintering, the vacuum sintering temperature is 1750℃, the holding time is 8h, then air annealing is carried out in a muffle furnace, the annealing temperature is 1400℃, the annealing time is 8h, and the ceramic surface is polished to obtain a lens-shaped fluorescent ceramic, the linear transmittance of the ceramic at 800 nm is 78.5%.

[0049] Step two: preparation of (Sr, Ca) AlSiN3: Eu 2+ red fluorescent silica gel layer:

[0050] (1) Mix the silicone gel with (Sr, Ca) AlSiN3: Eu2+ Red fluorescent powder was uniformly mixed at a mass ratio of 1:0.1, and the mixture was defoamed under vacuum to obtain a mixed solution.

[0051] (2) The obtained mixture was evenly coated on the surface of the lens-shaped fluorescent ceramic and dried in a drying oven at 50°C for 0.5h to obtain the fluorescent conversion composite material.

[0052] The fluorescent conversion composite material was excited by blue laser light, and the output power density was 29.3 W / mm². 2 At that time, the luminous efficacy was 223 lm / W, such as Figure 4 As shown, the fluorescent conversion composite material exhibits excellent luminescence stability; its color rendering index is as high as 95.4, such as... Figure 3 As shown.

[0053] Example 2

[0054] This embodiment provides a high color rendering index and high luminous efficiency fluorescence conversion composite material for laser illumination, such as... Figure 1 As shown, a lens-shaped 0.5 at.% Ce:YAG fluorescent ceramic 2 and a CaAlSiN3:Eu coating on the fluorescent ceramic 2 are used. 2+ The fluorescent silicone layer 1 is composed of a lens-shaped fluorescent ceramic 2 with the following final parameters: curvature 0.3, bottom diameter 10mm, height 8mm; and the thickness of the fluorescent silicone layer 1 is 0.5mm.

[0055] like Figure 2 As shown, the preparation method includes the following steps:

[0056] Step 1: Preparation of Ce:YAG ceramic green body using gel casting method:

[0057] (1) Raw material powder preparation: according to the composition (Y 0.995 Ce 0.005 )3Al5O 12 Weigh 125g of raw material powder according to the stoichiometric ratio, add 0.625g of PEI, 0.75g of MgO, 0.625g of TEOS, and 150mL of anhydrous ethanol, and ball mill at 220r / min for 24h to obtain a mixed slurry; dry at 80℃ for 24h, sieve through a 300-mesh sieve, and calcine in a muffle furnace at 1000℃ to obtain Ce:YAG ceramic powder;

[0058] (2) Injection molding slurry preparation: 0.625 g of acrylamide, 1.875 g of tetramethylammonium hydroxide, 3.75 g of acrylamide, 0.375 g of N-N'methylenebisacrylamide, 19.4 g of pure water were added to the Ce:YAG ceramic powder prepared in step (1), and after ball milling at 200 r / min for 12 h, the slurry was filtered out, the solid content of the slurry was 60 vol.%, and after vacuum degassing, 200 μL of tetramethyl ethylenediamine was added and mixed uniformly;

[0059] (3) Gel injection molding: pour the mixed slurry into a customized mold, heat initiate at 80℃, and solidify into a shape;

[0060] (4) Drying and degassing: the cured body is dried in a constant temperature and humidity box at 60℃ and 80% humidity for 36 h, and then put into a muffle furnace for degassing, the degassing temperature is 900℃, the degassing time is 72 h, and the Ce:YAG ceramic blank is obtained;

[0061] (5) The ceramic blank is put into a vacuum sintering furnace and sintered at a temperature of 1800℃ for 30 h, and then air annealed in a muffle furnace at a temperature of 1450℃ for 16 h, and the lens-shaped Ce:YAG fluorescent ceramic is obtained after polishing the ceramic surface. The straight-line transmittance of the ceramic at 800 nm is 74.3%.

[0062] Step two: preparation of CaAlSiN3:Eu 2+ Red fluorescent silica gel layer:

[0063] (1) The organic silica gel and CaAlSiN3:Eu 2+ red fluorescent powder are uniformly mixed in a mass ratio of 1:5, and a mixed solution is prepared after vacuum degassing in a vacuum degassing machine;

[0064] (2) The obtained mixed solution is evenly applied on the surface of the lens-shaped fluorescent ceramic, and dried in a 120℃ drying oven for 2 h to obtain a fluorescent conversion composite material.

[0065] The fluorescent conversion composite material is excited by blue light laser, and when the output power density is 29.3 W / mm 2 , the fluorescent ceramic device emits light stably, and the luminous efficiency is 197 lm / W; the color rendering index is as high as 90.9.

[0066] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement made by any person skilled in the art within the technical range disclosed by the present application, as long as it is within the spirit and principles of the present application, should be covered within the protection scope of the present application.

Claims

1. A high color rendering index high luminous efficacy fluorescent conversion composite material for laser illumination, characterized by, The fluorescent conversion composite is composed of a lens-shaped fluorescent ceramic and a red fluorescent silica gel layer coated on the surface of the fluorescent ceramic, the fluorescent ceramic emits yellow-green light under excitation of blue excitation light, and the red fluorescent silica gel layer emits red light under excitation of the blue excitation light; In the formula, the fluorescent ceramic has a curvature of 0.2-0.9, a bottom diameter of 5-20 mm, and a height of 5-20 mm; and the fluorescent silica gel layer has a thickness of 0.1-2 mm. The fluorescent ceramic has a composition of (RE 1-x Ce x )3Al5O 12 , wherein RE is one or more of Y, Lu, Ga, Gd, Tb, x is the mole percentage of Ce-doped RE sites, and 0.0001≤x≤0.

005. The fluorescent conversion composite is prepared by the following steps: Step 1: preparing a lens-shaped fluorescent ceramic by a gel casting method; Step 2: preparing a red fluorescent silica gel layer: (1) uniformly mixing an organic silica gel and red fluorescent powder, and then obtaining a mixed solution after vacuum degassing; (2) uniformly coating the mixed solution on the surface of the lens-shaped fluorescent ceramic, and then drying in an oven for 0.5-10 h to obtain the fluorescent conversion composite.

2. The high color rendering index, high luminous efficacy phosphor converted composite for laser lighting of claim 1, wherein, The specific steps of preparing the lens-shaped fluorescent ceramic by the gel casting method are as follows: (1.1) Preparation of raw material powder: according to the components (RE 1-x Ce x )3Al5O 12 The stoichiometric ratio of each element in the mixture is weighed, wherein RE is one or more of Y, Lu, Ga, Gd, and Tb, 0.0001≤x≤0.005; a dispersant PEI, a sintering aid MgO and TEOS, and anhydrous ethanol are added, and ball milling is performed to obtain a mixed slurry; Drying the slurry, sieving, and then calcining to obtain a fluorescent ceramic powder; (1.2) preparing a mold slurry: adding a dispersant acrylamide, a pH regulator tetramethylammonium hydroxide, a monomer acrylamide, a crosslinking agent N-N'methylenebisacrylamide, and pure water to the fluorescent ceramic powder prepared in step (1.1), ball-milling, filtering out the slurry, vacuum degassing, adding a catalyst tetramethyl ethylenediamine, and uniformly mixing; (1.3) gel casting: pouring the mixed slurry into a customized mold, and then performing thermal initiation at 50-80 ℃ to solidify and form; (1.4) drying and degassing: drying the solidified body in a constant-temperature and constant-humidity box for 12-36 h, and then placing the dried body in a muffle furnace for degassing to obtain a fluorescent ceramic body; (1.5) sintering the ceramic body in a vacuum sintering furnace to obtain a lens-shaped fluorescent ceramic, and then performing air annealing in a muffle furnace, and then polishing the surface of the ceramic to obtain the lens-shaped fluorescent ceramic.

3. The high color rendering index, high luminous efficacy phosphor converted composite for laser lighting of claim 2, wherein, In step (1.1), the amount of the dispersant added is 0.1-0.5 wt% of the total mass of the raw materials; the amount of MgO added is 0.1-0.6 wt% of the total mass of the raw materials; the amount of TEOS added is 0.3-0.5 wt% of the total mass of the raw materials; the ball-milling speed is 160-220 r / min, and the ball-milling time is 12-24 h; the drying temperature is 50-80 ℃, and the drying time is 6-24 h; the mesh size of the sieve is 80-300 meshes; and the muffle calcination temperature is 800-1000 ℃.

4. The high color rendering index, high luminous efficacy phosphor converted composite for laser lighting of claim 2, wherein, In step (1.2), the amount of the dispersant added is 0.25-0.5 wt% of the total mass of the raw materials, the amount of the pH regulator added is 1-1.5 wt% of the total mass of the raw materials, the amount of the monomer added is 2-3 wt% of the total mass of the raw materials, and the amount of the crosslinking agent added is 0.2-0.3 wt% of the total mass of the raw materials; the ball-milling speed is 140-200 r / min, and the ball-milling time is 8-12 h; and the solid content of the slurry is 40-60 vol.%.

5. The high color rendering index, high luminous efficacy, phosphor-conversion composite for laser lighting of claim 2, wherein, In step (1.4), the drying temperature is 25-60 ℃, the drying humidity is 30%-80%, the degassing temperature is 600-900 ℃, and the degassing time is 24-72 h.

6. The high color rendering index, high luminous efficacy, phosphor-conversion composite for laser lighting of claim 2, wherein, The vacuum sintering temperature in step (1.5) is 1740-1820℃, and the holding time is 8-30h; the annealing temperature is 1400-1500℃, and the annealing time is 8-16h.

7. The high color rendering index, high luminous efficacy, phosphor-conversion composite for laser lighting of claim 1, wherein, In step two (1), the red phosphor is selected from at least one of (Sr,Ca)AlSiN3:Eu 2+ , CaAlSiN3:Eu 2+ , K2GeF6:Mn 4+ , K2TiF6:Mn 4+ , K2SiF6:Mn 4+ , Y2O3:Eu 3+ , Sr2Si5N8:Eu 2+ , Ca[LiAl3N4]:Eu 2+ , Sr[LiAl3N4]:Eu 2+ , and Sr[Li2Al2O2N2]:Eu 2+ , and the mass ratio of the silicone glue to the red phosphor is 1:0.1-10.

0.

8. The method for preparing the high color rendering index and high luminous efficiency fluorescent conversion composite material for laser illumination according to claim 1, characterized in that, In step two (2), the drying temperature of the mixed solution is 50-150℃.

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