A high-reflection photovoltaic backplane film and preparation method thereof

Abstract

The present application discloses a high-reflection photovoltaic backplane film and a preparation method thereof, wherein the high-reflection photovoltaic backplane film comprises a black reflective layer, a white support layer and a black outer layer, wherein the preparation materials of the black reflective layer and the black outer layer comprise yttrium-doped Bi 2 Ce 2 O 7 Materials. This application uses Mg(OH) 2 / SBS / MMT‑TiO 2 Composite materials and Yttrium-doped Bi 2 Ce 2 O 7 The high-reflection photovoltaic backplane composite film is prepared by coordinated effect. The preparation process is simple. The prepared high-reflection photovoltaic backplane film has high reflective performance, and at the same time has good adhesion fastness, mechanical properties, hydrolysis resistance and weather resistance. It is beautiful and can significantly improve the service life of the photovoltaic backplane.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic cells, and in particular to a high-reflectivity photovoltaic backplane film and a preparation method thereof. Background Art

[0002] Solar cells, also known as photovoltaic cells, are devices that convert sunlight directly into electrical energy and are the core components of solar energy utilization technology. As the global energy crisis intensifies and environmental pollution becomes increasingly serious, solar cells are becoming increasingly important due to their clean and renewable characteristics. They can not only reduce dependence on fossil fuels and reduce greenhouse gas emissions, but also help achieve sustainable energy development. Solar cells have a wide range of applications, from small portable devices to large solar power stations. With the advancement of technology and the reduction of costs, the efficiency and reliability of solar cells continue to improve, making them occupy an increasingly important position in the global energy structure.

[0003] The photovoltaic backsheet is a key component of the solar cell module. It is located on the back of the module and its main function is to protect the cell from environmental factors such as moisture and ultraviolet rays. The backsheet is usually composed of multiple layers of materials, including PET film as the base film, and fluorine film or other plastic films adhered to both sides of the base film by adhesives. This structure not only provides good insulation and mechanical properties, but also has excellent weather resistance. The performance of the photovoltaic backsheet directly affects the reliability and service life of the photovoltaic module. Therefore, choosing the right backsheet material is crucial for the long-term stable operation of the photovoltaic module.

[0004] Improving the reflectivity of photovoltaic backsheets is one of the key factors in improving the overall performance of photovoltaic modules. High-reflectivity backsheets can more effectively reflect light that is not absorbed by the cells back to the cells, thereby increasing the light absorption of the cells and improving the photoelectric conversion efficiency. In addition, high-reflectivity backsheets can also reduce the temperature of the modules, reduce heat loss, and further improve power generation efficiency. Summary of the invention

[0005] The purpose of this application is to improve the reflectivity and service life of photovoltaic backplane films.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a highly reflective photovoltaic backplane film, including a black reflective layer, a white supporting layer and a black outer layer, wherein the raw materials for preparing the black reflective layer and the black outer layer include yttrium-doped Bi2Ce2O7 material.

[0007] As a preferred embodiment, the preparation method of the yttrium-doped Bi2Ce2O7 material is: yttrium oxide and Bi2Ce2O7 are mixed and then ground, calcined at a high temperature, and the product is cooled to obtain the yttrium-doped Bi2Ce2O7 material.

[0008] As another preference, the raw material for preparing the white support layer includes a Mg(OH)2 / SBS / MMT-TiO2 composite material.

[0009] As another preferred embodiment, the preparation method of the Mg(OH)2 / SBS / MMT-TiO2 composite material is: magnesium hydroxide, MMT-SiO2 powder, SBS copolymer and solvent are reacted in a reaction container, and the product is separated, cleaned and dried to obtain the Mg(OH)2 / SBS / MMT-TiO2 composite material.

[0010] As another preferred method, the preparation method of the MMT-SiO2 powder is: using montmorillonite as a carrier, introducing nano titanium oxide into the interlayer of the montmorillonite by titanium tetrachloride hydrolysis method, and calcining to obtain the MMT-SiO2 powder.

[0011] As another preference, the black reflective layer and the black outer layer are prepared with the same raw materials, including black pigment, the yttrium-doped Bi2Ce2O7 material, SBS copolymer, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET.

[0012] As another preference, the anti-hydrolysis agent is a combination of one or more of oxazoline compounds, epoxy compounds, aromatic carbodiimides, aliphatic carbodiimides, and polycarbodiimides.

[0013] The present application provides a method for preparing a high-reflection photovoltaic backplane film, comprising the following preparation steps: S1: grinding yttrium oxide and Bi2Ce2O7 and then calcining them to prepare yttrium-doped Bi2Ce2O7 material; S2: introducing nano-TiO2 into the interlayer of montmorillonite by titanium tetrachloride hydrolysis method, and obtaining MMT-TiO2 powder after calcination, reacting magnesium hydroxide, the MMT-TiO2 powder, SBS copolymer and solvent in a reaction container, and obtaining Mg(OH)2 / SBS / MMT-TiO2 composite material after separation, washing and drying the product; S3: treating the black pigment with water; The material, the yttrium-doped Bi2Ce2O7 material, the SBS copolymer, the antioxidant, the anti-hydrolysis agent, the light stabilizer, other additives and the PET are melted and plasticized in a screw extruder to obtain a black reflective layer and a black outer layer; the Mg(OH)2 / SBS / MMT-TiO2 composite material, the antioxidant, the anti-hydrolysis agent, the light stabilizer, the other additives and the PET are melted and plasticized in a screw extruder to obtain a white supporting layer; the black outer layer, the white supporting layer and the black reflective layer are co-extruded to obtain the high-reflection photovoltaic backplane film.

[0014] As another preferred embodiment, the yttrium oxide and Bi2Ce2O7 are mixed in a mass ratio of (1-5): (10-20).

[0015] Further preferably, the S2 step is specifically as follows: introducing nano-TiO2 into the interlayer of montmorillonite by titanium tetrachloride hydrolysis method, obtaining MMT-TiO2 powder after calcination, mixing magnesium hydroxide, the MMT-TiO2 powder, SBS copolymer, dilute hydrochloric acid and purified water in a polytetrafluoroethylene-lined reactor, and reacting in a water bath in a 160-200 °C oven for 14-20 h, cooling the product to room temperature and centrifuging it, washing it with anhydrous ethanol and purified water in turn, and finally vacuum drying it at 50-70 °C for 4-8 h to obtain the Mg(OH)2 / SBS / MMT-TiO2 composite material.

[0016] Compared with the prior art, the beneficial effects of this application are:

[0017] (1) The highly reflective photovoltaic backplane film of the present application, by adding yttrium-doped Bi2Ce2O7 material to the raw materials for preparing the black reflective layer and the black outer layer, can make the photovoltaic backplane film have strong reflective performance and excellent mechanical properties;

[0018] (2) The highly reflective photovoltaic backplane film of the present application, by adding a Mg(OH)2 / SBS / MMT-TiO2 composite material to the white support layer, can enhance the reflectivity and weather resistance of the photovoltaic backplane film;

[0019] (3) The highly reflective photovoltaic backplane film of the present application selects an aromatic carbodiimide anti-hydrolysis stabilizer, which reacts chemically with the hydrolysis product carboxylic acid or water to inhibit catalytic hydrolysis degradation, extend the service life of the backplane, and has good anti-hydrolysis, high temperature resistance and antioxidant effects in various high temperature, humid and acid-base harsh environments. DETAILED DESCRIPTION

[0020] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0021] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0022] The high-reflectivity photovoltaic backplane of the present application includes a black reflective layer, a white supporting layer and a black outer layer, wherein the raw materials for preparing the white supporting layer include a Mg(OH)2 / SBS / MMT-TiO2 composite material, and the raw materials for preparing the black reflective layer and the black outer layer include a yttrium-doped Bi2Ce2O7 material.

[0023] Bi2Ce2O7 is a new type of compound with high near-infrared reflectivity and good ultraviolet absorption rate. Rare earth elements have important application prospects in the field of energy and environmental protection due to their unique physical and chemical properties such as magnetism, light, and electricity. This application increases the Bi2Ce2O7 lattice structure by doping Bi2Ce2O7 with the rare earth element yttrium to prepare yttrium-doped Bi2Ce2O7 material, which has strong reflective properties and excellent mechanical and optical properties.

[0024] The white support layer of the present application adds a Mg(OH)2 / SBS / MMT-TiO2 composite material, in which the magnesium hydroxide has a high reflectivity. The addition of a certain amount of magnesium hydroxide increases the solar reflectivity by 48%, which is 32% higher than the polymer matrix, and can effectively reflect sunlight, thereby reducing heat absorption. Titanium dioxide has the advantages of stable chemical properties, high toughness, oxidation resistance, high temperature resistance, antibacterial and high reflectivity. Montmorillonite (MMT) can act as a nucleating agent. Montmorillonite is combined with titanium dioxide to prepare MMT-TiO2 to improve the dispersibility and stability of TiO2 materials. It has good barrier properties and is not easy to thermally decompose. In addition, the excellent photocatalytic properties of MMT-TiO2, synergistically with the high reflectivity of Mg(OH)2, enhance the UV aging resistance of the Mg(OH)2 / SBS / MMT-TiO2 composite material and enhance the weather resistance of the backplane film.

[0025] SBS (Styrene-Butadiene-Styrene) copolymer is a thermoplastic elastomer made from styrene and butadiene through anionic polymerization. It has strong bonding strength and durability. And provides good waterproof performance. It reacts chemically with PET, and the two have strong compatibility, which promotes uniform dispersion of the system, plays a role in structural support, and provides good waterproof performance. In addition, SBS solves the problem of poor compatibility between materials in each layer and between the inner layer of PET and the backboard substrate EVA, effectively improving the polarity of the film and the interfacial bonding strength with EVA.

[0026] In some preferred embodiments, the yttrium-doped Bi2Ce2O7 material is synthesized as follows: yttrium oxide and Bi2Ce2O7 are mixed and ground, and calcined at a high temperature, and the product is cooled to room temperature to obtain the yttrium-doped Bi2Ce2O7 material.

[0027] In some embodiments, the preparation method of Mg(OH)2 / SBS / MMT-TiO2 composite material is as follows: using montmorillonite as a carrier, introducing nano-TiO2 into the montmorillonite interlayer by titanium tetrachloride hydrolysis method, and obtaining TiO2-supported montmorillonite MMT-TiO2 powder with a stable structure after calcination; reacting magnesium hydroxide, MMT-TiO2 powder, SBS copolymer and solvent in a reaction container, and obtaining Mg(OH)2 / SBS / MMT-TiO2 composite material after separation, washing and drying of the product.

[0028] In some preferred embodiments, the black reflective layer includes the following preparation raw materials: black pigment, yttrium-doped Bi2Ce2O7 material, SBS copolymer, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET.

[0029] In some embodiments, the raw materials for preparing the white support layer include the following materials: Mg(OH)2 / SBS / MMT-TiO2 composite material, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET.

[0030] In some embodiments, the raw materials for preparing the black outer layer include: black pigment, yttrium-doped Bi2Ce2O7 material, SBS copolymer, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET.

[0031] In some embodiments, the anti-hydrolysis agent is a combination of one or more of oxazoline compounds, epoxy compounds, aromatic carbodiimides, aliphatic carbodiimides, and polycarbodiimides. More preferably, the anti-hydrolysis agent is an aromatic carbodiimide. Aromatic carbodiimide anti-hydrolysis stabilizers react chemically with hydrolysis products such as carboxylic acids or water to inhibit catalytic hydrolysis degradation, extend service life, and have good anti-hydrolysis and hydrolysis resistance in various high temperature, humid, acid-base and harsh environments.

[0032] The present application selects an aromatic carbodiimide anti-hydrolysis stabilizer, which reacts chemically with the hydrolysis product carboxylic acid or water to inhibit catalytic hydrolysis degradation, extend the service life of the backplane, and has good anti-hydrolysis, high temperature resistance and anti-oxidation effects in various high temperature, humid and acid-base harsh environments, greatly improving the weather resistance and aging resistance of the backplane film, thereby ensuring a high reflectivity of the photovoltaic backplane to sunlight.

[0033] In some embodiments, the other auxiliary agent may be any one or more combinations of a curing agent, a dispersant, and a plasticizer.

[0034] In some embodiments, the light stabilizer is one or a mixture of two or more of bis(2,2,6,6-tetramethyl-1-octyloxy-4-piperidinyl) sebacate, 2-hydroxy-4-octyloxybenzophenone, 2-(2ˊ-hydroxy-5ˊ-methylphenyl)benzotriazole, 2-(2ˊ-hydroxy-3ˊ5ˊ-di-tert-butylphenyl)-5-chloro-benzotriazole, 2,2'-methylene-(6-(2H-benzotriazole)-4-tert-octyl)phenol, 2-cyano-3,3ˊ-diphenylacrylate, bis(2,2,6,6-tetramethylpiperidinol sebacate, pentaerythritol β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris(2,4-di-tert-butylphenol)phosphite. More preferably, the light stabilizer is a mixture of bis(2,2,6,6-tetramethyl-1-octyloxy-4-piperidinyl) sebacate and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0035] In some embodiments, the antioxidant is one or more combinations of 2,4-dimethyl-6-tert-butylphenol, 1-hydroxy-3-methyl-4-isopropylbenzene, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), N,N′-di-2-naphthyl-p-phenylenediamine, and 2,6-di-tert-butyl-α-dimethylamino-p-cresol. More preferably, the antioxidant is a combination of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0036] Since photovoltaic backplane films will discolor and degrade when exposed to ultraviolet rays for a long time, traditional PET materials will have chain breaking problems when oxidized, and the carboxyl groups generated by chain breaking will further catalyze the cracking of PET polyester, thereby accelerating the aging of the film. This application uses a mixture of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol as an antioxidant to significantly reduce yellowing and aging, and at the same time synergizes with titanium dioxide to avoid chain breakage caused by aggregation of material molecular chains and enhance the stability of the system.

[0037] The present application also provides a method for preparing a highly reflective photovoltaic backplane film, comprising the following preparation steps:

[0038] S1: grinding yttrium oxide and Bi2Ce2O7 and calcining them to prepare yttrium-doped Bi2Ce2O7 material;

[0039] S2: Nano-TiO2 is introduced into the interlayer of montmorillonite by hydrolysis of titanium tetrachloride, and MMT-TiO2 powder is obtained after calcination. Magnesium hydroxide, MMT-TiO2 powder, SBS copolymer and solvent are reacted in a reaction vessel, and the product is separated, washed and dried to obtain Mg(OH)2 / SBS / MMT-TiO2 composite material;

[0040] S3: melt and plasticize the black pigment, yttrium-doped Bi2Ce2O7 material, SBS copolymer, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET in a screw extruder to prepare a black reflective layer and a black outer layer;

[0041] The Mg(OH)2 / SBS / MMT-TiO2 composite material, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET are melt-plasticized in a screw extruder to prepare a white support layer;

[0042] The black outer layer, the white support layer and the black reflective layer are co-extruded to obtain the high reflective photovoltaic backplane film of the present application.

[0043] In some embodiments, yttrium oxide and Bi2Ce2O7 are mixed in a mass ratio of (1-5):(10-20) and then ground. The temperature of high-temperature calcination after grinding is 750-850°C.

[0044] In some embodiments, the magnesium hydroxide, MMT-TiO2 powder, SBS copolymer and solvent prepared in step S2 are mixed in a polytetrafluoroethylene-lined reactor, and reacted in a water bath in a 160-200 °C oven for 14-20 h. The product is cooled to room temperature and centrifuged, washed with anhydrous ethanol and purified water in turn, and finally vacuum dried at 50-70 °C for 4-8 h to obtain a Mg(OH)2 / SBS / MMT-TiO2 composite material.

[0045] In some preferred embodiments, the raw materials for synthesizing the Mg(OH)2 / SBS / MMT-TiO2 composite material are magnesium hydroxide, MMT-TiO2 powder, SBS copolymer, purified water and dilute hydrochloric acid.

[0046] This application uses PET as the base material to prepare a low-cost, green and environmentally friendly fluorine-free photovoltaic backplane film. The PET film has excellent optical properties, as well as excellent insulation, tensile resistance and anti-aging properties, solving the problems of short service life, environmental pollution and high cost of traditional fluorine-containing PVDF films.

[0047] The present application uses the coordinated effect of Mg(OH)2 / SBS / MMT-TiO2 composite material and yttrium-doped Bi2Ce2O7 to prepare a high-reflection photovoltaic backplane composite film. The preparation process is simple, and the prepared high-reflection photovoltaic backplane film has high reflective performance, as well as good adhesion, mechanical properties, hydrolysis resistance and weather resistance. It is beautiful and can significantly improve the service life of the photovoltaic backplane.

[0048] Example 1

[0049] A highly reflective photovoltaic backplane film is prepared, comprising the following steps:

[0050] S1: Yttrium-doped Bi2Ce2O7 material was synthesized by solid phase reaction method. Yttrium oxide and Bi2Ce2O7 were weighed in a ratio of 2:15 and then fully ground and mixed in a mortar for 30 min. The mixture was placed in a crucible and calcined at 800 °C for 2 h. Finally, the product was cooled to room temperature to obtain yttrium-doped Bi2Ce2O7 material;

[0051] S2: Using montmorillonite as a carrier, nano-TiO2 was introduced into the interlayer of montmorillonite by titanium tetrachloride hydrolysis method, and a stable structure of MMT-TiO2 white powder was obtained after calcination at 550 °C; 10% Mg(OH)2, 5% MMT-TiO2, 3% SBS, 1.2% dilute hydrochloric acid, and 85% purified water were ultrasonically stirred for 40 min, transferred to a polytetrafluoroethylene-lined reactor, reacted in a 180 °C oven in a water bath for 16 h, cooled to room temperature and centrifuged, repeatedly washed with anhydrous ethanol and purified water, and finally the product was vacuum dried at 65 °C for 6 h to obtain Mg(OH)2 / SBS / MMT-TiO2 composite material;

[0052] S3: 5% perylene black dye, 6% yttrium-doped Bi2Ce2O7 material, 8% SBS copolymer, 0.5% antioxidant, 1% aromatic carbodiimide, 0.6% light stabilizer, 1.2% other additives and the balance PET masterbatch are mixed uniformly in a high-speed mixer, and the mixed raw materials are added to a screw extruder, and extruded and melted at a temperature of 220 ° C and a screw speed of 15 r / min to obtain a black reflective layer and a black outer layer;

[0053] 15% Mg(OH)2 / SBS / MMT-TiO2 composite material, 0.5% antioxidant, 1% aromatic carbodiimide, 0.6% light stabilizer, 1.2% other additives and the remaining PET masterbatch were mixed evenly in a high-speed mixer, and the mixed raw materials were added into a screw extruder, extruded and melted at a temperature of 220 °C and a screw speed of 15 r / min to obtain a white support layer;

[0054] The black reflective layer, the white supporting layer and the black outer layer are stacked in sequence, and the three-layer melt is formed by a co-extrusion casting machine to obtain the high-reflective photovoltaic backplane film of the present application.

[0055] Example 2

[0056] In step S3, the addition amount of yttrium-doped Bi2Ce2O7 material is adjusted to 4% to obtain a black reflective layer and a black outer layer. The other preparation steps are consistent with the preparation steps in Example 1.

[0057] Example 3

[0058] In step S3, the addition amount of yttrium-doped Bi2Ce2O7 material is adjusted to 8% to obtain a black reflective layer and a black outer layer. The other preparation steps are consistent with the preparation steps in Example 1.

[0059] Example 4

[0060] In step S3, the addition amount of Mg(OH)2 / SBS / MMT-TiO2 composite material is adjusted to 10%, and the other preparation steps are consistent with the preparation steps in Example 1.

[0061] Example 5

[0062] In step S3, the addition amount of Mg(OH)2 / SBS / MMT-TiO2 composite material is adjusted to 20%, and the other preparation steps are consistent with the preparation steps in Example 1.

[0063] Comparative Example 1

[0064] In step S3, no yttrium-doped Bi2Ce2O7 material is added to obtain the black reflective layer and the black outer layer of the comparative example. The other preparation steps are consistent with the preparation steps in Example 1 to obtain the photovoltaic backplane film of Comparative Example 1.

[0065] Comparative Example 2

[0066] In step S3, the Mg(OH)2 / SBS / MMT-TiO2 composite material is not added to prepare the white support layer of the comparative example. The other preparation steps are consistent with the preparation steps in Example 1 to prepare the photovoltaic backplane film of comparative example 2.

[0067] Performance Testing

[0068] Adhesion test was performed according to ASTM D3359-09 tape method. Water vapor transmission rate test was performed according to the test method in BG / T 26253-2010 after hydrolysis treatment under 85% relative humidity. UV resistance test standard requirements of HGT 3862-2006 were used to test the samples at 120KWh / m 2 The yellowing index value △b of the back sheet film is measured with reference to GB / T 3979-2008, and the wavelength range is 380 to 1200 nm. The test results of each embodiment and each comparative example are recorded in the following Table 1.

[0069] Table 1 Performance test results of high reflective photovoltaic backplane film

[0070]

[0071] By analyzing the performance test results of the embodiments and comparative examples in Table 1, the present application can obtain better reflectivity and bonding strength, and has anti-yellowing performance and water vapor permeability barrier properties by adding Mg(OH)2 / SBS / MMT-TiO2 composite material to the white supporting layer and adding yttrium-doped Bi2Ce2O7 material to the black outer layer and the black reflective layer.

[0072] In Examples 1 to 3, the addition amount of yttrium-doped Bi2Ce2O7 material was adjusted, which had a certain influence on various properties of the photovoltaic backplane film. When the addition amount of yttrium-doped Bi2Ce2O7 material was 6%, higher reflectivity and bonding strength could be achieved, and the anti-yellowing performance was good.

[0073] In Example 1, Example 4 and Example 5, the addition amount of the Mg(OH)2 / SBS / MMT-TiO2 composite material was adjusted. From the performance test results, it can be seen that when the addition amount of the Mg(OH)2 / SBS / MMT-TiO2 composite material is 15%, better performance can be obtained.

[0074] In summary, the high-reflectivity photovoltaic backplane film of the present application has a high reflectivity, excellent anti-yellowing performance and anti-water vapor permeability performance, and can be well connected and bonded with the EVA backplane to prevent the photovoltaic backplane film from falling off from the photovoltaic cell assembly. The high-reflectivity photovoltaic backplane film of the present application can better adapt to the harsh outdoor environment, better extend the service life of the photovoltaic backplane, and the higher reflectivity can improve the photoelectric conversion efficiency.

[0075] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. A highly reflective photovoltaic backplane film, characterized in that: It includes a black reflective layer, a white supporting layer and a black outer layer, wherein the raw materials for preparing the black reflective layer and the black outer layer include yttrium-doped Bi2Ce2O7 material, and the raw materials for preparing the white supporting layer include Mg(OH)2 / SBS / MMT-TiO2 composite material; The preparation method of the yttrium-doped Bi2Ce2O7 material is as follows: yttrium oxide and Bi2Ce2O7 are mixed and ground, calcined at a high temperature, and the product is cooled to obtain the yttrium-doped Bi2Ce2O7 material; The preparation method of the Mg(OH)2 / SBS / MMT-TiO2 composite material is as follows: magnesium hydroxide, MMT-TiO2 powder, SBS copolymer and solvent are reacted in a reaction container, and the product is separated, cleaned and dried to obtain the Mg(OH)2 / SBS / MMT-TiO2 composite material; The preparation method of the MMT-TiO2 powder is as follows: using montmorillonite as a carrier, introducing nano titanium oxide into the interlayer of the montmorillonite by a titanium tetrachloride hydrolysis method, and calcining to obtain the MMT-TiO2 powder.

2. The high reflective photovoltaic backsheet film according to claim 1, characterized in that: The raw materials for preparing the black reflective layer and the black outer layer are consistent, including black pigment, the yttrium-doped Bi2Ce2O7 material, SBS copolymer, antioxidant, anti-hydrolysis agent, light stabilizer, other additives and PET. The other additives can be any one or more combinations of curing agent, dispersant and plasticizer.

3. The high reflective photovoltaic backsheet film according to claim 2, characterized in that: The anti-hydrolysis agent is a combination of one or more of oxazoline compounds, epoxy compounds, aromatic carbodiimides, and aliphatic carbodiimides.

4. A method for preparing a highly reflective photovoltaic backplane film, characterized in that: The method comprises the following preparation steps: S1: grinding yttrium oxide and Bi2Ce2O7 and calcining them to prepare yttrium-doped Bi2Ce2O7 material; S2: introducing nano-TiO2 into the interlayer of montmorillonite by hydrolysis of titanium tetrachloride, obtaining MMT-TiO2 powder after calcination, reacting magnesium hydroxide, the MMT-TiO2 powder, SBS copolymer and solvent in a reaction vessel, and obtaining Mg(OH)2 / SBS / MMT-TiO2 composite material after separation, washing and drying of the product; S3: Melt and plasticize the black pigment, the yttrium-doped Bi2Ce2O7 material, the SBS copolymer, the antioxidant, the anti-hydrolysis agent, the light stabilizer, other additives and the PET in a screw extruder to obtain a black reflective layer and a black outer layer; melt and plasticize the Mg(OH)2 / SBS / MMT-TiO2 composite material, the antioxidant, the anti-hydrolysis agent, the light stabilizer, the other additives and the PET in a screw extruder to obtain a white support layer; co-extrude the black outer layer, the white support layer and the black reflective layer to obtain the high-reflection photovoltaic backplane film, and the other additives can be any one or more combinations of curing agents, dispersants and plasticizers.

5. The method for preparing a highly reflective photovoltaic backplane film according to claim 4, characterized in that: The yttrium oxide and Bi2Ce2O7 are mixed in a mass ratio of (1-5): (10-20).

6. The method for preparing a highly reflective photovoltaic backplane film according to claim 4, characterized in that: The S2 step is specifically as follows: introducing nano-TiO2 into the interlayer of montmorillonite by titanium tetrachloride hydrolysis method, obtaining MMT-TiO2 powder after calcination, mixing magnesium hydroxide, the MMT-TiO2 powder, SBS copolymer, dilute hydrochloric acid and purified water in a polytetrafluoroethylene-lined reactor, and reacting in a water bath in an oven at 160-200°C for 14-20 h, cooling the product to room temperature and then centrifuging it, washing it with anhydrous ethanol and purified water in turn, and finally vacuum drying it at 50-70°C for 4-8 h to obtain the Mg(OH)2 / SBS / MMT-TiO2 composite material.

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