Composite material for solar concentrator and preparation method thereof

Abstract

The present invention belongs to the field of organic and inorganic composite materials, and specifically relates to a composite material for solar concentrators and a preparation method thereof. The composite material for solar concentrators comprises quartz glass, a high molecular polymer, a fluorescent material and a scattering material. The high molecular polymer is formed by thermal curing pentaerythritol triacrylate under the initiator of azobisisobutyronitrile; the fluorescent material is Tb 3+ The device is composed of hollow MgF2 nanoparticles doped with silicon dioxide (SiO2) particles (400-600 nm) as the scattering material. A polymer, fluorescent material, and scattering material are coated on the surface of fluorescent quartz glass. The resulting device can collect and transmit sunlight, with important applications in architecture and photovoltaics.

Description

Technical Field

[0001] The present invention belongs to the field of organic and inorganic composite materials, and in particular relates to a composite material for a solar concentrator and a preparation method thereof. Background Art

[0002] With environmental pollution and the energy crisis worsening, the development of green energy is urgently needed. Solar energy, a clean, environmentally friendly, and renewable energy source, is gaining increasing attention, driving the rapid development of solar technology. Solar cells convert sunlight into electricity. However, most solar cells directly receive sunlight, requiring a large number of cells, resulting in high costs and a large footprint. Efficiently collecting sunlight and reducing the cost of solar cells are significant challenges.

[0003] Solar fluorescent concentrators (LSCs) are promising light-concentrating devices. They are coupled with small-area solar cells for efficient solar-to-electrical energy conversion. LSCs consist of fluorescent materials, optical waveguides, and solar cells. When the fluorescent concentrator is illuminated, the fluorescent material absorbs and re-emit light through fluorescence. Due to total internal reflection, the light is directed to the edge of the concentrator, where it connects to the solar cell. This allows for increased utilization of light energy by increasing the area of ​​the concentrator without increasing the area of ​​the solar cell.

[0004] Most combinations of fluorescent materials and optical waveguides involve coating the surface of the waveguide material with inorganic luminescent particles. However, direct coating of the inorganic particles can result in poor adhesion to the waveguide surface, making them prone to detachment. Coatings made from a composite of organic polymers and inorganic particles can improve adhesion, but the polymers fill the gaps between the inorganic particles, increasing the coating's refractive index and, consequently, light reflection, leading to light energy loss. Furthermore, the differing polarities of inorganic particles and organic polymers make it difficult to prepare a stable sol, making it difficult to create a uniform coating and resulting in increased scattering. Summary of the Invention

[0005] In order to overcome the drawbacks of the prior art, the present invention provides a composite material for a solar concentrator and a preparation method thereof.

[0006] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0007] The composite material for solar concentrators includes quartz glass, high molecular polymer, fluorescent material and scattering material. The high molecular polymer is formed by thermal curing pentaerythritol triacrylate under the initiator of azobisisobutyronitrile; the fluorescent material is formed by Tb 3+The invention is composed of doped hollow MgF2 nanoparticles; the scattering material is SiO2 particles of 400 to 600 nm; the high molecular polymer, fluorescent material and scattering material are compositely coated on the surface of fluorescent quartz glass.

[0008] High-molecular-weight polymers act as adhesives, improving adhesion. Hollow particles reduce the coating's refractive index, improving surface light reflection. Furthermore, compounding the resin monomer with the inorganic particles prevents direct compounding of the inorganic particles with long-chain polymers, thereby enhancing the stability of the sol. 400-600nm SiO2 particles scatter light, allowing more scattered sunlight to be transmitted from the quartz glass to the solar cell.

[0009] It is further preferred as a composite material for solar concentrators.

[0010] Preferably, high molecular polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 particles are:

[0011] High molecular weight polymer: 10 to 30 parts by mass;

[0012] Tb 3+ : 0.2~0.5 mass parts;

[0013] Hollow MgF2 nanoparticles: 10-40 parts by mass;

[0014] SiO2 particles: 4 to 8 parts by mass.

[0015] The collocation of the above-mentioned particles and the content of the high molecular polymer will directly affect the adhesion and refractive index of the coating. The more high molecular polymer content there is, the denser the coating is and the better the adhesion is, but the refractive index of the dense coating will be higher, causing its reflectivity to increase. MgF2 is the bulk material with the lowest refractive index found in nature, and hollow MgF2 material can further reduce the refractive index, and its ratio can regulate the refractive index of the entire coating. In addition, fluoride is a good carrier for rare earth ion lattice doping and is used as a fluorescent material in the present invention.

[0016] Preferably, the thickness of the high molecular polymer, fluorescent material and scattering material compositely coated on the surface of the fluorescent quartz glass is 400-700 nm.

[0017] The above thickness is critical, according to Fresnel's law of reflection: when the thickness and refractive index of the coating satisfy the following two formulas, the reflectivity will be minimized at a specific wavelength.

[0018] n1d=(2k+1)λ0 / 4, k=0, 1, 2, 3…

[0019] n1=(n0×n s )1 / 2

[0020] Where: n0, n1, n s λ0, λ0, and d represent the refractive indexes of air, coating, and quartz glass, respectively, the wavelength of incident light, and coating thickness. Silicon solar cells respond to wavelengths between 380 and 1100 nm. When k = 0, the reflectivity decreases most widely, with an optimal thickness of 70 to 225 nm. When k = 1, the optimal thickness is 210 to 675 nm. Theoretically, the average reflectivity is lowest when k = 0. However, too thin a thickness presents two problems: first, the scattering particles become too large, and second, light conversion and scattering are inadequate. Therefore, we chose a thickness of 210 to 675 nm. However, the SiO2 particles are 400 to 600 nm in size. Therefore, we adjusted the coating thickness to 400 to 700 nm. This reduces reflectivity while maintaining its light collection capacity.

[0021] The present invention also provides a method for preparing a composite material for a solar concentrator, comprising the following steps:

[0022] S1. Preparation of MgF2:Tb 3+ Nanoparticles: magnesium acetate tetrahydrate, Tb2O3, n-propanol, hydrofluoric acid and hydrochloric acid are vigorously stirred and then poured into the polytetrafluoroethylene liner of the reactor. They are heated at 150-180℃ for 6 hours. After the reaction is completed, MgF2:Tb 3+ Nanoparticles;

[0023] S2. Preparation of SiO2 nanoparticles: Tetraethyl orthosilicate, anhydrous ethanol, and aqueous ammonia were used to prepare SiO2 nanoparticles via hydrolysis polymerization, followed by stirring for 6 hours and aging at room temperature for 2 days. Finally, the SiO2 nanoparticles were centrifuged.

[0024] S3, prepare sol: take the MgF2:Tb obtained in step S1 3+ The nanoparticles and the SiO2 nanoparticles obtained in step S2 are dispersed in a mixed solvent of isopropyl alcohol and methyl isobutyl ketone, and after stirring evenly, pentaerythritol triacrylate and azobisisobutyronitrile are added and stirred evenly to obtain a composite sol;

[0025] S4, coating: coating the composite sol on the surface of the quartz glass by 3 to 6 cycles of immersion pulling;

[0026] S5. Curing: Place the glass sample in an oven at 80°C for 5 to 10 minutes.

[0027] It is further preferred as a preparation method of a composite material for solar concentrators.

[0028] Preferably, the added amounts of magnesium acetate tetrahydrate, Tb2O3, n-propanol, hydrofluoric acid and hydrochloric acid in step S1 are: 10-15 parts by mass, 0.1-0.25 parts by mass, 40 parts by mass, 4 parts by mass and 4 parts by mass, respectively.

[0029] Preferably, the added amounts of tetraethyl orthosilicate, anhydrous ethanol and aqueous ammonia in step S2 are 10-15 parts by mass, 40-60 parts by mass and 15-20 parts by mass, respectively.

[0030] Preferably, the MgF2:Tb in step S3 3+ The added amounts of nanoparticles, SiO2 nanoparticles, isopropyl alcohol, methyl isobutyl ketone, pentaerythritol triacrylate, and azobisisobutyronitrile are 1-4 mass parts, 0.4-0.8 mass parts, 20-40 mass parts, 10-20 mass parts, 1-3 mass parts, and 0.1-0.3 mass parts, respectively.

[0031] Preferably, the pulling speed of the immersion pulling method in step S4 is 75 to 150 mm / min.

[0032] The beneficial effects of the present invention compared to the prior art are:

[0033] (1) Compared with the original technology, the composite material coated on the quartz glass surface has better adhesion.

[0034] (2) Compared to existing technologies, the present invention adjusts the thickness and refractive index of the coating. The hollow MgF2 particles can serve as a fluorescent material and also adjust the refractive index of the coating. When the coating thickness is appropriate, the reflectivity can be reduced, thereby reducing the loss of light energy.

[0035] (3) The composite material of the present invention is an inorganic particle MgF2:Tb 3+ The sol is composed of SiO2 particles and a high molecular weight polymer. Due to the different polarities of inorganic particles and long-chain organic polymers, the prepared sol is not stable. However, in the present invention, polymer monomers are compounded with inorganic particles to make it more stable. After thermal curing and initiator, the monomers are polymerized into long-chain polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the working principle of composite materials used in solar concentrators;

[0037] Figure 2 (a) is Tb prepared in Example 1 3+ Transmission electron micrograph of doped MgF2 nanoparticles, Figure 2 (b) is Tb 3+ Excitation spectrum of doped MgF2 nanoparticles, Figure 2 (c) is Tb in Examples 1-43+ Emission spectrum of doped MgF2 nanoparticles. The inset is a photograph of the sample in Example 1 under 365nm UV light.

[0038] Figure 3 is a scanning electron microscope photograph of SiO2 particles prepared in Example 2;

[0039] Figure 4 (a) and 4(b) are scanning electron microscope images of the coatings prepared in Comparative Example 1 and Example 3, respectively;

[0040] Figure 5 (a) and (b) are micrographs of the scratches of the coatings prepared in Comparative Example 1 and Example 3 under a 3H pencil, respectively;

[0041] Figure 6 1 is the reflectance spectrum of the samples prepared in Examples 1 to 3 and Comparative Examples 2 to 3;

[0042] Figure 7 This is a photo of composite materials used in solar concentrators under 365nm ultraviolet light;

[0043] Figure 8 These are the IV curves of the samples prepared in Examples 1 to 3. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to comparative examples and embodiments.

[0045] Example 1

[0046] This embodiment provides a composite material for a solar concentrator and a preparation method thereof:

[0047] Composite material for solar concentrator: including quartz glass, high molecular polymer, fluorescent material and scattering material, the high molecular polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 are:

[0048] High molecular weight polymer: 10 parts by mass;

[0049] Tb 3+ : 0.2 parts by mass;

[0050] Hollow MgF2 nanoparticles: 10 parts by mass;

[0051] SiO2 particles: 4 parts by mass, size 400 nm;

[0052] The high molecular polymer, fluorescent material and scattering material are compositely coated on the surface of the fluorescent quartz glass with a thickness of 400 nm.

[0053] The preparation method comprises the following steps:

[0054] S1. Preparation of MgF2:Tb 3+ Nanoparticles: 10 parts by mass of magnesium acetate tetrahydrate, 0.1 parts by mass of Tb2O3, 40 parts by mass of n-propanol, 4 parts by mass of hydrofluoric acid and 4 parts by mass of hydrochloric acid, stirred vigorously and then poured into the polytetrafluoroethylene liner of the reactor, heated at 150 ° C for 6 hours, and after the reaction was completed, MgF2:Tb was obtained by centrifugation. 3+ Nanoparticles;

[0055] S2. Preparation of SiO2 nanoparticles: 10 parts by mass of tetraethyl orthosilicate, 40 parts by mass of anhydrous ethanol, and 15 parts by mass of aqueous ammonia were used to prepare SiO2 nanoparticles via hydrolysis polymerization. The mixture was stirred for 6 hours and then aged at room temperature for 2 days. Finally, the SiO2 nanoparticles were centrifuged to obtain the SiO2 nanoparticles.

[0056] S3, prepare sol: take 1 mass part of MgF2:Tb obtained in step S1 3+ The nanoparticles and 0.4 parts by mass of the SiO2 nanoparticles obtained in step S2 are dispersed in a mixed solvent of 20 parts by mass of isopropyl alcohol and 10 parts by mass of methyl isobutyl ketone, and after stirring evenly, 1 part by mass of pentaerythritol triacrylate and 0.1 part by mass of azobisisobutyronitrile are added and stirred evenly to obtain a composite sol;

[0057] S4, coating: coating the composite sol on the quartz glass surface by immersion pulling method at a speed of 75 mm / min for 3 times;

[0058] S5. Curing: Place the glass sample in an oven at 80°C for 5 minutes.

[0059] Example 2

[0060] This embodiment provides a composite material for a solar concentrator and a preparation method thereof:

[0061] Composite material for solar concentrator: including quartz glass, high molecular polymer, fluorescent material and scattering material, the high molecular polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 are:

[0062] High molecular weight polymer: 30 parts by mass;

[0063] Tb 3+ : 0.5 parts by mass;

[0064] Hollow MgF2 nanoparticles: 40 parts by mass;

[0065] SiO2 particles: 8 parts by mass, size 600 nm;

[0066] The high molecular polymer, fluorescent material and scattering material are compositely coated on the surface of the fluorescent quartz glass with a thickness of 700 nm.

[0067] The preparation method comprises the following steps:

[0068] S1. Preparation of MgF2:Tb 3+ Nanoparticles: 15 parts by mass of magnesium acetate tetrahydrate, 0.25 parts by mass of Tb2O3, 40 parts by mass of n-propanol, 4 parts by mass of hydrofluoric acid and 4 parts by mass of hydrochloric acid, vigorously stirred evenly, then poured into the polytetrafluoroethylene liner of the reactor, heated at 150 ° C for 6 hours, after the reaction is completed, MgF2:Tb 3+ Nanoparticles;

[0069] S2. Preparation of SiO2 nanoparticles: 15 parts by mass of tetraethyl orthosilicate, 60 parts by mass of anhydrous ethanol, and 20 parts by mass of aqueous ammonia were used to prepare SiO2 nanoparticles via hydrolysis polymerization. The mixture was stirred for 6 hours and then aged at room temperature for 2 days. Finally, the SiO2 nanoparticles were centrifuged to obtain the SiO2 nanoparticles.

[0070] S3, prepare sol: take 4 parts by mass of MgF2:Tb obtained in step S1 3+ The nanoparticles and 0.8 parts by mass of the SiO2 nanoparticles obtained in step S2 are dispersed in a mixed solvent of 40 parts by mass of isopropyl alcohol and 20 parts by mass of methyl isobutyl ketone, and after stirring evenly, 3 parts by mass of pentaerythritol triacrylate and 0.3 parts by mass of azobisisobutyronitrile are added and stirred evenly to obtain a composite sol;

[0071] S4, coating: coating the composite sol on the quartz glass surface by immersion pulling method at a speed of 150 mm / min for 3 times;

[0072] S5. Curing: Place the glass sample in an oven at 80°C for 10 minutes.

[0073] Example 3

[0074] This embodiment provides a composite material for a solar concentrator and a preparation method thereof:

[0075] Composite material for solar concentrator: including quartz glass, high molecular polymer, fluorescent material and scattering material, the high molecular polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 are:

[0076] High molecular weight polymer: 20 parts by mass;

[0077] Tb 3+ : 0.3 parts by mass;

[0078] Hollow MgF2 nanoparticles: 30 parts by mass;

[0079] SiO2 particles: 8 parts by mass, size 500 nm;

[0080] The high molecular polymer, fluorescent material and scattering material are compositely coated on the surface of the fluorescent quartz glass with a thickness of 600nm.

[0081] The preparation method comprises the following steps:

[0082] S1. Preparation of MgF2:Tb 3+ Nanoparticles: 12 parts by mass of magnesium acetate tetrahydrate, 0.15 parts by mass of Tb2O3, 40 parts by mass of n-propanol, 4 parts by mass of hydrofluoric acid and 4 parts by mass of hydrochloric acid, vigorously stirred evenly, then poured into the polytetrafluoroethylene liner of the reactor, heated at 150 ° C for 6 hours, after the reaction is completed, MgF2:Tb 3+ Nanoparticles;

[0083] S2. Preparation of SiO2 nanoparticles: 12 parts by mass of tetraethyl orthosilicate, 50 parts by mass of anhydrous ethanol, and 18 parts by mass of aqueous ammonia were used to prepare SiO2 nanoparticles via hydrolysis polymerization. The mixture was stirred for 6 hours and then aged at room temperature for 2 days. Finally, the SiO2 nanoparticles were centrifuged to obtain the SiO2 nanoparticles.

[0084] S3, prepare sol: take 2 parts by mass of MgF2:Tb obtained in step S1 3+ The nanoparticles and 0.6 parts by mass of the SiO2 nanoparticles obtained in step S2 are dispersed in a mixed solvent of 40 parts by mass of isopropyl alcohol and 20 parts by mass of methyl isobutyl ketone, and after stirring evenly, 3 parts by mass of pentaerythritol triacrylate and 0.3 parts by mass of azobisisobutyronitrile are added and stirred evenly to obtain a composite sol;

[0085] S4, coating: coating the composite sol on the quartz glass surface by immersion pulling method at a speed of 100 mm / min for 6 times;

[0086] S5. Curing: Place the glass sample in an oven at 80°C for 10 minutes.

[0087] Examples 4 to 7

[0088] The difference between Examples 4 to 7 and Example 1 is that the pulling speeds of the immersion pulling are 80 mm / min, 100 mm / min, 120 mm / min and 140 mm / min, respectively, and the corresponding coating thicknesses are 430 nm, 510 nm, 590 nm and 660 nm, respectively.

[0089] Comparative Example 1

[0090] Comparative Example 1 differs from Example 3 in that no high molecular weight polymer is added:

[0091] Composite material for solar concentrator: including quartz glass, fluorescent material and scattering material, the polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 are:

[0092] Tb 3+ : 0.3 parts by mass;

[0093] Hollow MgF2 nanoparticles: 30 parts by mass;

[0094] SiO2 particles: 8 parts by mass, size 500 nm;

[0095] The thickness of the fluorescent material and the scattering material compositely coated on the surface of the fluorescent quartz glass is 600 nm.

[0096] Comparative Examples 2-3

[0097] Comparative Examples 2 to 3 differ from Example 1 in that the thickness of the coatings are 200 nm and 300 nm, respectively.

[0098] Figure 1 This diagram illustrates the working principle of composite materials used in solar concentrators. The diagram shows that when sunlight strikes the composite material, it is absorbed and converted by the fluorescent material, emitting light in all directions. Scattering particles also scatter sunlight into the quartz glass, where it is then conducted to the solar cell.

[0099] Figure 2 (a) is Tb prepared in Example 1 3+ Transmission electron micrograph of doped MgF2 nanoparticles, Figure 2 (b) is Tb 3+ Excitation spectrum of doped MgF2 nanoparticles, Figure 2 (c) is Tb in Examples 1-4 3+ The emission spectrum of the doped MgF2 nanoparticles, the inset is a photograph of the sample in Example 1 under 365nm ultraviolet light. This shows that the fluorescent material with a low refractive index was successfully prepared.

[0100] Figure 3 This is a scanning electron microscope photograph of the SiO2 particles prepared in Example 2. It can be seen that the size of the SiO2 nanoparticles is about 600nm and has a certain light scattering ability.

[0101] Figure 4(a) and (b) are scanning electron micrographs of the coatings prepared in Comparative Example 1 and Example 3, respectively. It is clearly evident from the images that without the polymer composite, the coatings are loose. However, the composite coatings exhibit excellent compactness, which theoretically improves the coating's adhesion.

[0102] Figure 5 (a) and (b) are micrographs of the scratches of the coatings prepared in Comparative Example 1 and Example 3 under a 3H pencil, respectively. The experimental results show that the coatings composited with high molecular weight polymers have better adhesion.

[0103] Figure 6 (a) is the reflectance spectra of the samples prepared in Examples 1 to 3 and Comparative Examples 2 to 3, Figure 6 Curves (b) through (d) are partial curves from Figure 6(a). It can be seen that the reflectivity of quartz glass covered with coatings between 200nm and 700nm is lower than that of pure glass, which reduces light scattering losses. Furthermore, the reflectivity of coatings between 400nm and 700nm is lower than that of coatings with a thickness of 200nm. Furthermore, the thicker the coating, the more light it absorbs.

[0104] Figure 7 This is a photograph of the composite material for solar concentrators prepared in Example 1 under 365nm ultraviolet light. It can be seen intuitively that the composite material can absorb ultraviolet light and emit it in all directions, which is then conducted to the solar cell by the quartz glass.

[0105] Figure 8 The IV curves of the samples prepared in Examples 1 to 3 are shown. The experimental results show that coating the composite material on quartz glass for solar concentrators can improve the conduction of sunlight and increase the photoelectric conversion efficiency of solar cells.

[0106] In summary, the composite material for solar concentrators has good adhesion on quartz glass, and can reduce reflectivity and increase light transmission performance under a specific coating thickness.

[0107] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A composite material for a solar concentrator, comprising quartz glass, a high molecular polymer, a fluorescent material, and a scattering material, characterized in that: The high molecular polymer is formed by thermally curing pentaerythritol triacrylate under the initiator of azobisisobutyronitrile; The fluorescent material is composed of Tb 3+ Doped hollow MgF2 nanoparticles; The scattering material is SiO2 particles with a diameter of 400-600 nm; The high molecular polymer, fluorescent material and scattering material are compositely coated on the surface of the fluorescent quartz glass; The high molecular polymer, Tb 3+ , the masses of hollow MgF2 nanoparticles and SiO2 are: High molecular weight polymer: 10-30 parts by mass; Tb 3+ : 0.2~0.5 parts by mass; Hollow MgF2 nanoparticles: 10-40 parts by mass; SiO2 particles: 4-8 parts by mass; The thickness of the high molecular polymer, fluorescent material and scattering material compositely coated on the surface of the fluorescent quartz glass is 400-700 nm.

2. A method for preparing the composite material for solar concentrators according to claim 1, characterized in that: The following steps are involved: S1. Preparation of Tb 3+ Doping hollow MgF2 nanoparticles: magnesium acetate tetrahydrate, Tb2O3, 40 parts by mass of n-propanol, hydrofluoric acid and hydrochloric acid, vigorously stir evenly, then pour it into the polytetrafluoroethylene liner of the reactor, heat at 150~180℃ for 6h, after the reaction is completed, obtain Tb by centrifugation 3+ doped hollow MgF2 nanoparticles; S2. Preparation of SiO2 nanoparticles: SiO2 nanoparticles were prepared by hydrolysis polymerization of tetraethyl orthosilicate, anhydrous ethanol, and ammonia water, and stirred for 6 h, then aged at room temperature for 2 days, and finally centrifuged to obtain SiO2 nanoparticles; S3, prepare sol: take Tb obtained in step S1 3+ The doped hollow MgF2 nanoparticles and the SiO2 nanoparticles obtained in step S2 are dispersed in a mixed solvent of isopropyl alcohol and methyl isobutyl ketone, and after stirring evenly, pentaerythritol triacrylate and azobisisobutyronitrile are added and stirred evenly to obtain a composite sol; S4, coating: coating the composite sol on the surface of the quartz glass by 3 to 6 cycles of immersion pulling method; S5. Curing: Place the glass sample in an oven at 80°C for 5 to 10 minutes.

3. The method for preparing a composite material for a solar concentrator according to claim 2, characterized in that: The added amounts of magnesium acetate tetrahydrate, Tb2O3, n-propanol, hydrofluoric acid, and hydrochloric acid in step S1 are 10-15 parts by mass, 0.1-0.25 parts by mass, 40 parts by mass, 4 parts by mass, and 4 parts by mass, respectively.

4. The method for preparing a composite material for a solar concentrator according to claim 2, wherein: The added amounts of tetraethyl orthosilicate, anhydrous ethanol, and aqueous ammonia in step S2 are 10-15 parts by mass, 40-60 parts by mass, and 15-20 parts by mass, respectively.

5. The method for preparing a composite material for a solar concentrator according to claim 2, wherein: Tb in step S3 3+ The addition amounts of doped hollow MgF2 nanoparticles, SiO2 nanoparticles, isopropyl alcohol, methyl isobutyl ketone, pentaerythritol triacrylate, and azobisisobutyronitrile are 1-4 parts by mass, 0.4-0.8 parts by mass, 20-40 parts by mass, 10-20 parts by mass, 1-3 parts by mass, and 0.1-0.3 parts by mass, respectively.

6. The method for preparing a composite material for a solar concentrator according to claim 2, wherein: The pulling speed of the immersion pulling method in step S4 is 75-150 mm / min.

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