Application of polymer multilayer optical film in field of crystalline silicon cells

Abstract

The invention discloses application of a polymer multilayer optical film in the field of crystalline silicon cells, and relates to the technical field of photovoltaic cells, the polymer multilayer optical film covers the surface of a crystalline silicon cell, and the polymer multilayer optical film is a multi-film layer formed by alternately stacking high-refractive-index film layers and low-refractive-index film layers; the polymer multilayer optical film is prepared by a lamination multiplication co-extrusion technology. The optical film prepared by the preparation process can reflect light of a specific wave band in a visible light region, presents a corresponding color, and can be colored when being applied to a solar crystalline silicon cell, the reflection wave band of the optical film is mainly concentrated in the visible light region, the band pass is narrower, and the influence on the power generation efficiency of the crystalline silicon cell is relatively small. Compared with a traditional colored adhesive film solar cell, under the same illumination condition, a crystalline silicon cell based on the polymer multilayer optical film can reduce the operating temperature of the solar cell, improve the working efficiency of the cell and have brighter colors.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and particularly to the application of a polymer multi-layer optical film in the field of crystalline silicon cells. Background Art

[0002] With the increasing global demand for clean energy, photovoltaic power generation has received extensive attention as a sustainable energy solution. Crystalline silicon cells are one of the most widely used photovoltaic cell technologies at present. However, their monotonous black appearance cannot combine aesthetics and functionality, which limits their extensive application in other fields such as building integrated photovoltaics (BIPV), vehicle integrated photovoltaics (VIPV), and wearable electronic products. On the other hand, there are also many problems with traditional methods of colorizing photovoltaic modules.

[0003] In view of the above limitations of crystalline silicon cells, currently, three technical routes have been explored in the field of colored photovoltaics, namely, the colorization technology of the photovoltaic absorption layer, the colorization technology of the photovoltaic encapsulation film, and the colorization technology of the photovoltaic front plate, aiming to solve the colorization problem, but each route has its own defects to be overcome.

[0004] The colorization technology of the photovoltaic absorption layer focuses on obtaining color effects in the photovoltaic chip manufacturing process. For example, developing and preparing photovoltaic materials with their own colors or adding special color substances to the photovoltaic core layer. However, the photovoltaic cells prepared by this technology have extremely low efficiency and are difficult to meet the usage requirements. In addition, colorization can also be achieved by combining quantum dot materials with the photovoltaic cell absorption layer and adjusting the relevant properties of the quantum dots to change the absorption and emission of light by the absorption layer. However, the current cost of quantum dot materials is high, and their stability and service life need to be improved.

[0005] The colorization technology of the photovoltaic encapsulation film mainly realizes colorization by adding pigment materials to the film. This method will cause the power generation efficiency of the photovoltaic module to be greatly reduced due to the absorption of light by the pigment and serious heating. Moreover, over time and under the influence of environmental factors, the pigment is extremely prone to fading, which will further affect the long-term use effect and aesthetics of the entire photovoltaic module; the pigment may also be unevenly dispersed in the film, which will also lead to uneven color effects and affect the stability of the photovoltaic module.

[0006] Regarding the technology of colorizing the front panel of photovoltaic cells, traditionally, colored glass or enameled glass is used for component encapsulation. This technology has low technical difficulty and low cost, but both have low light transmittance, seriously affecting the power generation efficiency of photovoltaic modules. In recent years, coating and structural color strategies have gradually become popular with the progress of technology. Coating technology mainly deposits on the front panel glass substrate of photovoltaic cells using dielectrics such as silicon oxide and tantalum oxide, and relies on the optical properties of the thin film to selectively process light to achieve color presentation. However, the process of coating technology is complex and the preparation efficiency is low. It requires a high level of professional technology and precise production equipment support. The selection and preparation of coating materials have strict requirements, and the actual application difficulty and cost investment are high. Structural color is generated by the scattering, interference, diffraction, etc. of light by micro-nano structures, which can change the propagation path and reflection characteristics of light, so that the photovoltaic cell presents a specific color. However, the preparation of micro-nano structures also requires complex processes and high input costs. Summary of the Invention

[0007] The purpose of the present invention is to provide an application of a polymer multi-layer optical film in the field of crystalline silicon cells, which solves the problems of low power generation efficiency of colored crystalline silicon cells and single color of crystalline silicon cells.

[0008] The present invention is realized through the following technical solutions. Specifically, an application of a polymer multi-layer optical film in the field of crystalline silicon cells is provided. The polymer multi-layer optical film covers the surface of the crystalline silicon cell, and the polymer multi-layer optical film is a multi-film layer formed by alternating stacking of high refractive index film layers and low refractive index film layers;

[0009] The polymer multi-layer optical film has at least one reflection peak in the wavelength range of 380nm - 780nm. The reflection peak with the largest reflectivity in this range is the first reflection peak, and the reflectivity of the first reflection peak is 90% - 99.99%; the average transmittance in the wavelength range of 380nm - 780nm is above 80%;

[0010] The polymer multi-layer optical film is obtained by a layer-by-layer doubling co-extrusion technology, and the preparation method includes the following steps:

[0011] (1) Stack two or more polymer-based melts to form a layered polymer-based melt with two or more layers;

[0012] (2) Multiply the layered polymer-based melt to obtain a multi-layer polymer-based melt;

[0013] (3) Extrude the multi-layer polymer-based melt, stretch and cool it, and wind it up to obtain the polymer multi-layer optical film.

[0014] As a further optimized solution of the present invention, the polymer includes at least one of polymethyl methacrylate (PMMA), polypentene (TPX), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), and polystyrene (PS).

[0015] As a further optimized solution of the present invention, the polymer includes a modified polymer, and the modified polymer includes a blend-modified polymer, a filled-modified polymer, a chemically-modified polymer, or a composite material.

[0016] As a further optimized solution of the present invention, the thickness of the polymer multi-layer optical film is 10 μm - 300 μm.

[0017] As a further optimized solution of the present invention, the thickness of the polymer multi-layer film is 11.4 μm, and the polymer multi-layer film has a reflection peak in the wavelength range of 380 nm - 780 nm, with a reflectivity of more than 92% and an average transmittance of more than 80%.

[0018] As a further optimized solution of the present invention, step (2) is specifically to multiply the layered polymer-based melt through a multiplication system including a layer multiplier, wherein the layer multiplier includes at least one of an equal-layer layer multiplier and an unequal-layer layer multiplier.

[0019] As a further optimized solution of the present invention, the number of the layer multipliers is 1 - 10.

[0020] As a further optimized solution of the present invention, when the number of the layer multipliers is greater than 1, the layer multipliers form the multiplication system in a series connection manner.

[0021] As a further optimized solution of the present invention, the types of the layer multipliers include at least one of "one-to-two type", "one-to-three type", "one-to-four type", and "one-to-five type".

[0022] The present invention has the following technical effects compared with the prior art:

[0023] (1) Appearance improvement: The polymer multi-layer optical film is a multi-layer film structure formed by alternately laminating polymer materials with different refractive indexes. By adjusting the optical properties of each layer, the optical film can reflect light in a specific wavelength band in the visible light region and present corresponding colors. Applying it to a solar crystalline silicon cell can make it have colors and increase the diversity of appearance.

[0024] (2) Power generation efficiency guarantee: The reflection band of the polymer multi-layer optical film mainly focuses on the visible light region and has a relatively narrow bandpass, so the impact on the power generation efficiency of the crystalline silicon cell is relatively small.

[0025] (3) Different from the absorption strategy adopted by ordinary colored plastic films, the polymer multi-layer optical film of the present invention adopts a reflection strategy, which can make the color more vivid and bright. In addition, since it does not absorb too much sunlight to cause the film to heat up, it can further reduce the operating temperature of the solar cell and improve the battery efficiency.

[0026] (4) Preparation process advantages: The polymer multi-layer optical film of the present invention is prepared by using a layer-by-layer multiplication co-extrusion technology. This technology uses a layer-by-layer multiplier to multiply the layered polymer matrix melt, which can precisely control the number and thickness of the film layers. At the same time, the extrusion process can ensure the uniform mixing and forming of the polymer materials. This preparation process has the advantages of low raw material cost, high film-forming efficiency, strong functionality, precisely controllable thickness, solvent-free polymer materials, and continuous processing, and is easy to industrialize. Compared with some traditional methods for preparing colored photovoltaic modules, such as the method of making a colored coating layer on the surface of the battery chip, the preparation process of the present invention can significantly shorten the production cycle and reduce the production cost. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of a colored solar crystalline silicon cell;

[0028] Figure 2 It is a schematic structural diagram of the polymer multi-layer optical film given in Example 1;

[0029] Figure 3 It is a schematic summary diagram of the reflectance of the polymer multi-layer optical film prepared in Example 1 at different wavelengths;

[0030] Figure 4 It is a schematic diagram of the reflectance of the maximum reflection peak (the first reflection peak) at 550 nm (green light band) of the polymer multi-layer optical film with different total film layers provided in Example 2. Detailed Embodiments

[0031] The following further describes the present invention in detail. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention according to the above application content.

[0032] The preparation method of the polymer multi-layer optical film disclosed in the present invention includes the following steps:

[0033] Step 1: Stack the polymer matrix melt to form a layered polymer matrix melt with two or more layers;

[0034] Specifically, the polymer-based melt is made of two or more polymer materials with different refractive indices. That is, the moisture in the polymer materials is first removed by drying, and then different polymer materials are respectively added to the extruder and melted and extruded through heating to obtain different polymer-based melts. It should be noted that the process conditions such as the heating temperature and pressure of the extruder need to be adjusted according to the melting characteristics of the selected polymer materials to ensure that the polymer-based melt can be smoothly extruded and has appropriate fluidity and uniformity.

[0035] Subsequently, different polymer-based melts flow to the feed block, and are alternately stacked in the feed block to initially form a layered polymer-based melt with more than two layers. The thickness ratio of each film layer in the layered polymer-based melt is adjusted by controlling the extrusion amount of each extruder and the rotation speed of the roller.

[0036] In some embodiments, the light transmittance between the selected polymer materials is greater than 90%, and the processing temperatures (melting point, decomposition temperature) between the polymer materials are similar, having a certain compatibility. Specifically, the polymer materials that can be selected are: polymethyl methacrylate (PMMA), polypentene (TPX), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), polystyrene (PS).

[0037] In some embodiments, to further optimize the performance of the optical film, the polymer materials also include corresponding modified polymers, such as blend-modified polymers, filled-modified polymers, chemically modified polymers or composite materials.

[0038] Step 2: Multiply the layered polymer-based melt to obtain a multi-layer polymer-based melt.

[0039] Specifically, the layered polymer-based melt is multiplied by the multiplication system of the laminating multiplier. After the layered polymer-based melt enters the multiplication system, under the action of the laminating multiplier, after multiple shunting and multiplication operations, a multi-layer polymer-based melt is finally obtained. During this process, by controlling the working parameters of each laminating multiplier (such as shunting ratio, flow control, etc.) and the process conditions of the entire multiplication system (such as temperature, pressure, etc. remain stable), the thickness and composition of each layer of melt are ensured to be uniform.

[0040] In some embodiments, the laminating multiplier includes at least one of an equal-layer laminating multiplier and an unequal-layer laminating multiplier, and the number is 1 to 10, and the types include at least one of "one-to-two type", "one-to-three type", "one-to-four type" and "one-to-five type". Multiple laminating multipliers can be connected in series to form a multiplication system to realize the preparation of a multi-layer optical film with 2 n (n = 1, 2, 3... n) layers.

[0041] Step 3: Extrude, stretch, and cool the multi-layer polymer-based melt, and finally wind it up to obtain the polymer multi-layer optical film.

[0042] Specifically, the multi-layer polymer-based melt is extruded through the die orifice of an extruder. Process conditions such as the extrusion temperature, pressure, and extrusion speed of the extruder are adjusted according to the characteristics of the polymer material and the final requirements of the optical film. For example, for some polymer materials with relatively high melting points, the extrusion temperature needs to be correspondingly increased to ensure that the melt can be smoothly extruded and maintain good molding properties.

[0043] The extruded melt is stretched and cooled by multiple rollers and finally wound up into a polymer multi-layer optical film. According to the characteristics of the polymer material and the performance requirements of the multi-layer optical film, the cooling rate and temperature are reasonably controlled to ensure that the optical film has good optical and mechanical properties.

[0044] The polymer multi-layer optical film obtained through the above preparation is a multi-film layer with alternating high-refractive-index film layers and low-refractive-index film layers. By regulating the refractive index difference between the high- and low-refractive-index layer materials, the polymer multi-layer optical film has a relatively narrow reflection band in the visible light region, which can avoid the near-infrared band mainly absorbed by crystalline silicon cells for power generation, ensuring that while endowing the crystalline silicon cell with a saturated, bright, and colorful appearance, the impact on the power generation efficiency of the crystalline silicon cell is relatively small, overcoming the defect that traditional colorization methods (such as adding pigments to the adhesive film, color coating on the surface of the cell) easily cause the film to heat up and reduce the working efficiency of the cell.

[0045] In some embodiments, the reflection band of the polymer multi-layer optical film is designed by the transmission matrix method and TFCalc software, and the bandwidth and position of the reflection band are accurately calculated and adjusted corresponding to the theoretical parameters of the optical film (total thickness, single film layer thickness, number of film layers, etc.) to achieve the reflection of light in a specific band in the visible light region. This spectral regulation can make the optical film present various colors, which can solve the problem of the single color of solar crystalline silicon cells and increase the diversity of the product appearance.

[0046] In some embodiments, the thickness of the polymer multi-layer optical film is 10 μm to 300 μm, and the number of layers of the polymer multi-layer optical film is not less than 2 layers. The polymer multi-layer optical film has at least one reflection peak in the wavelength range of 380 nm to 780 nm. The reflection peak with the largest reflectivity in this range is 50% to 99.99%, preferably 90% to 99.99%; the average transmittance in the wavelength range of 380 nm to 780 nm is above 80%. Since the main band of light absorbed by crystalline silicon cells for power generation is concentrated in the near-infrared band, the transmittance of the optical film in this band meets the requirements, and the reflection design in the visible light region is reasonable, so the impact on the power generation efficiency of crystalline silicon cells is relatively small.

[0047] In some embodiments, the polymer multi-layer optical film obtained by the above preparation is used as a color polymer multi-layer film in a color solar crystalline silicon cell. The structural schematic diagram of the color solar crystalline silicon cell is as shown in Figure 1 shown.

[0048] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0049] Example 1

[0050] A specific polymer multi-layer optical film provided in this embodiment specifically selects polymethyl methacrylate (PMMA) and polycarbonate (PC) as polymer materials. PC has a relatively high refractive index and can be used as a high refractive index film layer material; PMMA has a relatively low refractive index and can be used as a low refractive index film layer material. Both have relatively high transparency, similar processing temperatures and certain compatibility. Alternate combination of the two can construct a multi-layer structure with specific optical properties.

[0051] The dosage ratio of polymethyl methacrylate (PMMA) and polycarbonate (PC), by weight, includes 100 parts of PMMA masterbatch and 104 parts of PC masterbatch.

[0052] The preparation method includes the following steps:

[0053] Step 1: Stack to form a layered polymer-based melt: Transfer the above-mentioned PMMA masterbatch and PC masterbatch in the specified ratio to a dryer and dry them at 100 °C for 12 h to obtain dry PMMA masterbatch and PC masterbatch.

[0054] Add the above-prepared masterbatches to the feeding ports of two screw extruders, A and B, respectively. After being heated and melted by the screw extruders, polymer-based melt A and polymer-based melt B are obtained. The film layer formed by polymer-based melt A is called film layer A, and the film layer formed by polymer-based melt B is called film layer B. Polymer-based melt A and polymer-based melt B respectively flow through the flow channels to the feeding block, and are alternately stacked in the feeding block to initially form a two-layer layered polymer-based melt with an AB film layer structure and equal thickness of film layer A and film layer B.

[0055] Step 2: Multiply to obtain a multi-layer polymer-based melt: Use 3 groups of "one-to-four" equal-layer stacking multipliers to multiply the polymer-based melt to obtain a multi-layer polymer-based melt.

[0056] Step 3: Extrude and cool to form: The multi-layer polymer-based melt is extruded through the die orifice of the extruder, stretched and cooled by rollers, and finally wound into a polymer multi-layer optical film. The structure of the polymer multi-layer optical film is as shown in Figure 2 shown.

[0057] In Example 1, the total thickness of the polymer multi-layer optical film is designed to be 11.4 μm. The number of layers of the film is 128. The test results of the optical film characteristics show that the polymer multi-layer optical film has a reflection peak in the wavelength range of 380 nm to 780 nm (specifically at 550 nm), the reflectivity is above 92%, and the average transmittance in the wavelength range of 380 nm to 780 nm is above 80%.

[0058] Example 2

[0059] In the field of optical thin films, for the optical characteristic design of multi-layer film structures, it is often based on the principle of light interference. When light is perpendicularly incident on a multi-layer film, reflection and transmission occur at the interfaces of each film layer, and interference phenomena occur between the reflected lights. To achieve specific optical properties, such as reflection or transmission at a specific wavelength, it is necessary to precisely control the thickness of each film layer.

[0060] According to the theory of light interference, for a quarter-wavelength film stack (that is, high-refractive-index film layers and low-refractive-index film layers are alternately stacked, and the thickness of each film layer is one-quarter of the corresponding wavelength in the optical thickness of the film layer), when light is perpendicularly incident, constructive interference occurs at a specific wavelength, thereby achieving high reflection or other desired optical effects. The layer-by-layer multiplication technology can produce polymer multi-layer films with more than a thousand layers, and the thickness of a single film layer is only a few tens of nanometers. It exactly meets the interference conditions in the visible light band, so the corresponding visible light can be reflected by controlling the number of layers and the thickness of the thin film, making the thin film obtain the corresponding color.

[0061] On the basis of the polymer materials and preparation methods disclosed in Example 1, the reflection characteristics are further optimized by adjusting the total thickness and single-layer thickness of PC and PMMA, so that the film parameters of the polymer multi-layer optical film in different bands are as follows:

[0062] In the 750 nm - 620 nm band (red light band), the total thickness of PC is 6951.68 nm, the total thickness of PMMA is 7370.66 nm, and the total film thickness is 14322.34 nm. The reflection peak band should be covered, and its reflection band width ranges from 10 nm to 100 nm ( Figure 3 in which, a specific example is 670 nm - 700 nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10 nm - 100 nm);

[0063] In the 620 nm - 590 nm band (orange light band), the total thickness of PC is 6115.02 nm, the total thickness of PMMA is 6497.38 nm, and the total film thickness is 12612.40 nm. The reflection peak band should be covered, and its reflection band width ranges from 10 nm to 100 nm ( Figure 3Among them, a specific example is 590nm - 620nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm);

[0064] In the 590nm - 570nm band (yellow light band), the total thickness of PC is 5852.71nm, the total thickness of PMMA is 6224.08nm, and the total film thickness is 12076.79nm. The reflection peak band should be covered, and its reflection band width ranges from 10nm - 100nm ( Figure 3 Among them, a specific example is 570nm - 590nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm);

[0065] In the 570nm - 495nm band (green light band), the total thickness of PC is 5379.24nm, the total thickness of PMMA is 5731.51nm, and the total film thickness is 11110.75nm. The reflection peak band should be covered, and its reflection band width ranges from 10nm - 100nm ( Figure 3 Among them, a specific example is 524nm - 554nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm);

[0066] In the 495nm - 485nm band (cyan light band), the total thickness of PC is 4903.54nm, the total thickness of PMMA is 5237.91nm, and the total film thickness is 10141.45nm. The reflection peak band should be covered, and its reflection band width ranges from 10nm - 100nm ( Figure 2 Among them, a specific example is 475nm - 505nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm);

[0067] In the 485nm - 450nm band (blue light band), the total thickness of PC is 4638.03nm, the total thickness of PMMA is 4963.13nm, and the total film thickness is 9601.16nm. The reflection peak band should be covered, and its reflection band width ranges from 10nm - 100nm ( Figure 3 Among them, a specific example is 455nm - 470nm, indicating that the reflection peak band range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm).

[0068] In the 450nm - 380nm band (violet light band), the total thickness of PC is 4120.76nm, the total thickness of PMMA is 4420.39nm, and the total film thickness is 8541.15nm. The reflection peak band should be covered, and its reflection band width ranges from 10nm - 100nm ( Figure 3Among them, a specific example is 400nm - 430nm, indicating that the reflection peak wavelength range can be flexibly adjusted on this basis, and the width meets the requirements of 10nm - 100nm).

[0069] Figure 3 It is a summary diagram of the reflectivity of a 128 - layer polymer optical film corresponding to different wavelength bands. It can be seen that the reflectivity of the maximum reflection peak of the optical film in different wavelength bands is close to 100%.

[0070] Furthermore, Figure 4 It gives a schematic diagram of the reflectivity of the maximum reflection peak (the first reflection peak) of polymer optical films with different total numbers of layers at 550nm (green light wavelength band). It can be seen from the figure that the reflectivity of the first reflection peak of polymer optical films with different total numbers of layers at 550nm (green light wavelength band) is all between 40% and 100%. At the same time, the transmittance in the remaining wavelength bands remains above 80%. Furthermore, it can be seen from the figure that the more the total number of layers of the polymer optical film, the higher the reflectivity of the first reflection peak of the corresponding polymer optical film in different wavelength bands.

[0071] The above - described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. Application of a polymer multi-layer optical film in the field of crystalline silicon cells, characterized in that, The polymer multi-layer optical film covers the surface of the crystalline silicon cell, and the polymer multi-layer optical film is a multi-film layer formed by alternately laminating high refractive index film layers and low refractive index film layers; The polymer multi-layer optical film has at least one reflection peak in the wavelength range of 380nm - 780nm. The reflection peak with the maximum reflectivity in this range is the first reflection peak, and the reflectivity of the first reflection peak is 90% - 99.99%. The average transmittance in the wavelength range of 380nm - 780nm is above 80%; The polymer multi-layer optical film is prepared by a lamination multiplication co-extrusion technique. The preparation method includes the following steps: (1) Stack two or more polymer-based melts to form a layered polymer-based melt with two or more layers; (2) Multiply the layered polymer-based melt to obtain a multi-layer polymer-based melt; (3) Extrude, stretch, cool, and wind up the multi-layer polymer-based melt to obtain the polymer multi-layer optical film.

2. The application of a polymer multi-layer optical film according to claim 1 in the field of crystalline silicon cells, characterized in that, The polymer includes at least one of polymethyl methacrylate (PMMA), polypentene (TPX), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), and polystyrene (PS).

3. Use of a polymer multi-layer optical film according to claim 1 in the field of crystalline silicon cells, characterized in that, The polymer includes modified polymers, and the modified polymers include blended modified polymers, filled modified polymers, chemically modified polymers, or composite materials.

4. The application of a polymer multi-layer optical film according to claim 1 in the field of crystalline silicon cells, characterized in that: The thickness of the polymer multi-layer optical film is 10μm - 300μm.

5. Use of a polymer multi-layer optical film according to claim 1 in the field of crystalline silicon cells, characterized in that, The thickness of the polymer multi-layer optical film is 11.4μm. The polymer multi-layer film has a reflection peak in the wavelength range of 380nm - 780nm, and the reflectivity is above 92%, and the average transmittance is above 80%.

6. The application of a polymer multi-layer optical film according to claim 1 in the field of crystalline silicon cells, characterized in that, The specific step (2) is to multiply the layered polymer-based melt through a multiplication system including a lamination multiplier. Among them, the lamination multiplier includes at least one of an equal-layer lamination multiplier and an unequal-layer lamination multiplier.

7. An application of a polymer multi-layer optical film according to claim 6 in the field of crystalline silicon cells, characterized in that The number of the lamination multipliers is 1 - 10.

8. Use of a polymer multi-layer optical film according to claim 6 in the field of crystalline silicon cells, characterized in that, When the number of the lamination multipliers is greater than 1, the lamination multipliers form the multiplication system in a series connection manner.

9. An application of a polymer multi-layer optical film according to claim 6 in the field of crystalline silicon cells, characterized in that The types of the lamination multipliers include at least one of "one-to-two type", "one-to-three type", "one-to-four type", and "one-to-five type".

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