A photon gap boosting film, a preparation method thereof and a photovoltaic module

Abstract

This invention relates to the field of photovoltaic technology, and discloses a photon gap enhancement film, its preparation method, and a photovoltaic module. The photon gap enhancement film sequentially comprises a first weather-resistant transparent coating, an upper protective layer, a microprism structure layer, a lower substrate layer, and a second weather-resistant transparent coating. The microprism structure layer includes a plurality of periodically arranged right-angled triangular prism units, the first right-angled face of which is attached to the lower surface of the upper protective layer. The weather-resistant transparent coatings used in the first and second weather-resistant transparent coatings both include a weather-resistant resin matrix and functional fillers (including first and second functional fillers). The first functional filler is an optical conditioning filler comprising 3-8 wt% of the mass of the weather-resistant resin matrix; the second functional filler is an acetic acid absorbing filler comprising 2-5 wt% of the mass of the weather-resistant resin matrix. This photon gap enhancement film efficiently utilizes light from the gap region between solar cells to achieve power gain and effectively reduces power degradation due to damp heat aging of the module, improving its long-term reliability.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to a photon gap enhancement film, its preparation method, and a photovoltaic module. Background Technology

[0002] During the encapsulation process of solar photovoltaic (PV) modules, a certain width of blank area (also known as a gap area) is inevitably present between adjacent cells and between the cell and the PV frame. These gap areas are usually covered by transparent PV encapsulation films (such as EVA or POE encapsulation films) and upper cover plates (such as PV glass). Although these gap areas allow light to pass through, the transmitted light cannot directly reach the light-receiving surface of the cell (i.e., the upper surface of the cell). Instead, it shines on the PV backsheet or becomes a scattering loss, and cannot be effectively absorbed and utilized by the cell. Consequently, this portion of light cannot be converted into electrical energy. This unused light source reduces the overall photoelectric conversion efficiency and power output of the PV module. Furthermore, during the long-term operation of PV modules (e.g., over 25 years), the PV encapsulation film (especially EVA encapsulation film) will slowly degrade in humid and hot environments, producing acetic acid. The accumulation of acetic acid corrodes the grid lines and solder ribbons of the cells, leading to accelerated power degradation of the PV module and even inducing premature failure, severely affecting the lifespan of the PV module.

[0003] Currently, the industry generally improves the output power of photovoltaic modules by enhancing the photoelectric conversion efficiency of the solar cells themselves or optimizing electrical connections; or, as shown in publication CN112201721A, develops a gap reflective film placed below the solar cells to reflect light that passes through the gap area and the underlying encapsulating film (post-encapsulation material) back to the lower surface of the solar cells. However, the solution shown in CN112201721A prolongs the transmission path of light back to the surface of the solar cells, increasing light loss during transmission, thus limiting its effect on the power gain of photovoltaic modules. Therefore, existing technologies lack an economical, efficient, and more reliable solution for utilizing "gap light." Meanwhile, protection against acetic acid corrosion mainly relies on developing more stable photovoltaic encapsulating film materials, but the development cost is high. Therefore, there is an urgent need to develop a low-cost, highly efficient photon gap enhancement film for photovoltaic modules that can simultaneously improve the resistance to damp heat aging. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a photon gap enhancement film, its preparation method, and a photovoltaic module.

[0005] Based on this, the present invention discloses a photon gap enhancement film, which is a multilayer composite structure, comprising, from top to bottom: a first weather-resistant transparent coating, an upper protective layer, a microprism structure layer, a lower substrate layer, and a second weather-resistant transparent coating. The microprism structure layer includes a number of periodically arranged right-angled triangular prism units, and the first right-angled face of the right-angled triangular prism unit is attached to the lower surface of the upper protective layer; The weather-resistant transparent coatings used in the first and second weather-resistant transparent coatings both include a weather-resistant resin matrix and functional fillers dispersed in the weather-resistant resin matrix; the functional fillers include a first functional filler and a second functional filler; the first functional filler is an optical conditioning filler, which accounts for 3-8 wt% of the mass of the weather-resistant resin matrix; the second functional filler is an acetic acid absorbing filler, which accounts for 2-5 wt% of the mass of the weather-resistant resin matrix.

[0006] Preferably, the periodic spacing of the right-angled triangular prism unit is 50-200 micrometers, the height of the right-angled triangular prism unit is 20-100 micrometers, and the base angle α of the right-angled triangular prism unit is 30°-60°.

[0007] More preferably, the right-angled triangular prism unit is formed on the upper surface of the lower substrate layer by imprinting and photocuring liquid photocuring resin material (such as acrylic UV adhesive); the microprism structure layer is a transparent layer, the second right-angled face of its right-angled triangular prism unit is perpendicular to the upper surface of the lower substrate layer, and the inclined face of the right-angled triangular prism unit is a light refraction surface.

[0008] Preferably, the first functional filler is selected from one or more of nano-silica, nano-zirconia, and nano-alumina, and the particle size of the first functional filler is 100-500 nm. The second functional filler is selected from one or more of alkali metal modified molecular sieves, metal-organic framework materials, and surface-modified activated alumina; The weather-resistant resin matrix is ​​at least one of fluorinated modified acrylic resin, polyurethane resin, or silicone resin.

[0009] More preferably, the weather-resistant transparent coating used in the first weather-resistant transparent coating further includes: 8-20 wt% EVA resin, which accounts for 8-20 wt% of the mass of its weather-resistant resin matrix, and 13-20 wt% additives, which account for 13-20 wt% of the mass of its weather-resistant resin matrix. The weather-resistant transparent coating used in the second weather-resistant transparent coating also includes: 13-20 wt% of additives according to the mass of its weather-resistant resin matrix; The additive is one or more of the following: ultraviolet light absorber, dispersant, leveling agent, defoamer, and solvent.

[0010] More preferably, the thickness of the first weather-resistant transparent coating is 10-15 micrometers; and the thickness of the second weather-resistant transparent coating is 5-10 micrometers.

[0011] Preferably, the upper protective layer is a transparent PET film with a thickness of 20-50 micrometers; the lower substrate layer is a transparent PET film with a thickness of 20-80 micrometers; and the total thickness of the photon gap enhancement film is controlled at 100-250 micrometers.

[0012] This invention also discloses a method for preparing a photon gap enhancement film, comprising the following steps: S1. A liquid photocurable resin material is coated on the upper surface of the lower substrate layer, and then molded and photocured by an imprinting mold to form a microprism structure layer. S2. Cover the upper protective layer with the upper surface of the microprism structure layer, so that the upper protective layer is in contact with the upper surface of the microprism structure layer. S3. Apply and cure the first weather-resistant transparent coating and the second weather-resistant transparent coating on the upper surface of the upper protective layer and the lower surface of the lower substrate layer, respectively.

[0013] The present invention also discloses a photovoltaic module using a photon gap enhancement film, which includes, from top to bottom: an upper cover plate, an upper encapsulating film, a battery string, a lower encapsulating film and a lower cover plate, wherein the battery string includes a plurality of battery cells arranged at intervals in sequence, and the sides of the battery cells have gap regions. The photovoltaic module also includes a plurality of photon gap enhancement films arranged at intervals, wherein the photon gap enhancement film is a photon gap enhancement film as described above in this invention; the photon gap enhancement film is disposed between the upper cover plate and the upper encapsulation film, or between the upper encapsulation film and the cell string; each photon gap enhancement film covers the gap area of ​​the corresponding cell.

[0014] Preferably, the periodic arrangement direction of several right-angled triangular prism units in the microprism structure layer is parallel to the width direction of the gap region of the solar cells in the photovoltaic module.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Enhanced Power Gain and Reliability: The photon gap-inducing efficiency-enhancing film of this invention, through a carefully designed microprism structure, refracts light illuminating the gap region of the photovoltaic module cells onto the upper surface of the cells. This actively refracts previously wasted "gap light" onto the cells, increasing the effective light intake and significantly improving the photovoltaic module's light capture capability and power output (optical simulation and experimental verification show that it can increase the power of standard photovoltaic modules by more than 1.8%). Simultaneously, it is combined with weather-resistant transparent coatings (first and second weather-resistant transparent coatings) which not only provide excellent UV and hydrolysis resistance, protecting the upper protective layer, microprism structure layer, and lower substrate layer from environmental aging, but also, through the selection of specific functional fillers (including first and second functional fillers), effectively absorb acetic acid generated by the degradation of the photovoltaic encapsulation film, inhibiting corrosion of the cells from the source, improving their resistance to damp heat aging, effectively reducing power decay after damp heat aging, enhancing the long-term reliability of the photovoltaic module, and extending its service life.

[0016] Therefore, this photon gap enhancement film, through the combined optical refraction of the microprism structure and the functional weather-resistant transparent protective coating (such as the first weather-resistant transparent coating and the second weather-resistant transparent coating), efficiently utilizes the light energy in the gap area of ​​the photovoltaic module cells to achieve power gain, improves the resistance of photovoltaic modules to damp heat aging and reduces power decay after damp heat aging, thereby improving the long-term reliability of photovoltaic modules.

[0017] 2. Good process compatibility: The photon gap enhancement film of the present invention is thin and flexible, and can be directly embedded into the existing photovoltaic module lamination process without changing the core production line equipment. It has low implementation cost and is easy to promote industrialization.

[0018] 3. Flexible design: In addition, by adjusting the parameters of the microprism structure (such as bottom corner, periodic spacing, etc.) and the type and proportion of functional fillers in the weather-resistant transparent coating, it is possible to flexibly adapt to photovoltaic modules of different shapes and cell spacings to achieve customized efficiency enhancement. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the cross-sectional structure of a photon gap enhancement film according to the present invention.

[0020] Figure 2 for Figure 1 A magnified view of two right-angled triangular prism units in the microprism structure layer.

[0021] Figure 3 This is a schematic diagram of the cross-sectional structure of a photovoltaic module according to the present invention.

[0022] Figure 4This is a schematic diagram of light refraction in a photovoltaic module using a photon gap enhancement film according to the present invention.

[0023] Reference numerals: 1. Upper cover plate; 2. Photon gap enhancement film; 21. First weather-resistant transparent coating; 22. Upper protective layer; 23. Microprism structure layer; 231. Right-angled triangular prism unit; 2311. Inclined surface; 2312. First right-angled surface; 2313. Second right-angled surface; 24. Lower substrate layer; 25. Second weather-resistant transparent coating; 3. Upper encapsulation film; 4. Battery string; 41. Battery cell; 42. Gap area; 5. Lower encapsulation film; 6. Lower cover plate. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] A photon gap enhancement film of the present invention, see [link to relevant documentation]. Figure 1-2 It is a multi-layered composite structure, which includes, from top to bottom: a first weather-resistant transparent coating 21, an upper protective layer 22, a microprism structure layer 23, a lower substrate layer 24, and a second weather-resistant transparent coating 25.

[0026] The first weather-resistant transparent coating 21 is applied to the upper surface of the upper protective layer 22. The weather-resistant transparent coatings used in the first weather-resistant transparent coating 21 and the second weather-resistant transparent coating 25 both include: a weather-resistant resin matrix and functional fillers dispersed in the weather-resistant resin matrix.

[0027] The functional filler includes a first functional filler, which is an optical performance regulating filler used to optimize the coating's optical properties such as refractive index and transmittance, as well as its UV aging resistance. The first functional filler is selected from one or more of nano-silica, nano-zirconia, and nano-alumina. The particle size of the first functional filler is 100-500 nm. The first functional filler accounts for 3-8 wt% of the weather-resistant resin matrix. Excessive addition of the first functional filler will increase the coating's haze and reduce its transmittance; conversely, insufficient addition will reduce the light scattering by the filler particles, thereby reducing the optical efficiency of the photon gap enhancement film and ultimately lowering the photovoltaic module's power output.

[0028] The functional filler also includes a secondary functional filler, which is an acetic acid absorber used for the chemical adsorption of acetic acid molecules. The secondary functional filler is selected from one or more of alkali metal-modified molecular sieves, metal-organic frameworks (MOFs), and surface-modified activated alumina. The secondary functional filler accounts for 2-5 wt% of the weather-resistant resin matrix. If the amount of secondary functional filler added is too low, the coating's adsorption capacity for acidic substances will decrease, reducing the coating's protective effect on the photovoltaic module; conversely, if the amount of secondary functional filler added is too high, the coating performance will be reduced, leading to a higher risk of delamination during long-term aging and shortening the lifespan of the photovoltaic module.

[0029] The weather-resistant resin matrix is ​​at least one of fluorinated modified acrylic resin, polyurethane resin, or silicone resin.

[0030] The thickness of the first weather-resistant transparent coating 21 is 10-15 micrometers, and the first weather-resistant transparent coating 21 can generate adhesiveness at high temperatures (such as 130-150℃), and the adhesiveness will not disappear when the temperature decreases, so as to firmly adhere to the upper cover plate 1 of the photovoltaic module (e.g., Figure 3-4 (As shown). The tackiness of the first weather-resistant transparent coating 21 mainly comes from the EVA (ethylene-vinyl acetate copolymer) resin added to the weather-resistant transparent coating used in the first weather-resistant transparent coating 21. The EVA resin accounts for 8-20 wt% of the mass of the weather-resistant resin matrix in the weather-resistant transparent coating used in the first weather-resistant transparent coating 21.

[0031] The second weather-resistant transparent coating 25 is applied to the lower surface of the lower substrate layer 24. The thickness of the second weather-resistant transparent coating 25 is 5-10 micrometers.

[0032] The upper protective layer 22 is a transparent PET (polyethylene terephthalate) film with a thickness of 20-50 micrometers. The lower surface of the upper protective layer 22 covers and adheres to the microprism structure layer 23 to fix and protect the physical integrity of the microprism structure.

[0033] The microprism structure layer 23 is directly photopolymerized onto the upper surface of the lower substrate layer 24 using an imprinting process. The microprism structure layer 23 is a transparent layer. It comprises several periodically arranged right-angled triangular prism units 231. Each right-angled triangular prism unit 231 has a right-angled triangle cross-section. One right-angled facet (i.e., the first right-angled facet 2312) of the right-angled triangular prism unit 231 is attached to the lower surface of the upper protective layer 22, while the other right-angled facet (i.e., the second right-angled facet 2313) of the right-angled triangular prism unit 231 is perpendicular to the upper surface of the lower substrate layer 24. The inclined surface 2311 of the right-angled triangular prism unit 231 serves as the light incident / refracting surface. In practice, as... Figure 4As shown, light can be incident perpendicularly onto the right-angled surface (i.e., the first right-angled surface 2312) of the right-angled triangular prism unit 231 that is in contact with the lower surface of the upper protective layer 22. After entering the right-angled triangular prism unit 231, the light reaches the inclined surface 2311 of the right-angled triangular prism unit 231 (at this time, the inclined surface 2311 is the refracting surface of the light). The light is refracted by the inclined surface 2311 to the effective light-receiving surface of the adjacent solar cell 41, and then absorbed and utilized by the adjacent solar cell 41. Therefore, the light incident on the gap region 42 of the solar cell 41 can be effectively utilized, improving the light utilization rate and increasing the power generation of the photovoltaic module.

[0034] The periodic spacing of the right-angled triangular prism unit 231 (the periodic spacing is equivalent to...) Figure 1-2 The spacing between the right-angled faces (i.e., the second right-angled face 2313) of two adjacent right-angled triangular prism units 231 perpendicular to the upper surface of the lower substrate layer 24 is 50-200 micrometers, and the height of the right-angled triangular prism unit 231 (the height of the right-angled triangular prism unit 231 is the maximum thickness of the microprism structure layer 23) is 20-100 micrometers. The base angle α of the right-angled triangular prism unit 231 is optimized by optical simulation based on the packaging structure, and the preferred range is 30°-60° to ensure that the light rays incident perpendicularly to the gap region 42 of the battery cell 41 are refracted to the effective light-receiving surface of the adjacent battery cell 41 to the maximum extent. The right-angled triangular prism unit 231 is preferably an isosceles right-angled triangular prism unit.

[0035] The lower substrate layer 24 is a transparent PET (polyethylene terephthalate) film with a thickness of 20-80 micrometers. The total thickness of the photon gap enhancement film is controlled between 100-250 micrometers to ensure good flexibility and adhesion, making it suitable for lamination encapsulation processes.

[0036] The present invention provides a method for preparing a photon gap enhancement film, comprising the following steps: Step 1. Substrate preparation: Provide a clean, transparent PET film as the lower substrate layer 24.

[0037] Step 2. Molding of the microprism structure layer 23: A liquid photocurable resin material (such as an acrylic UV adhesive) is coated on the upper surface of the lower substrate layer 24. A precision roller mold with the target microprism structure is used for imprinting, while simultaneously subjecting the material to ultraviolet irradiation to cure the liquid photocurable resin material (curing conditions include: using an ultraviolet light source with a wavelength of 395nm and an energy of 2000-5000mw / cm²). 2 Cured at room temperature for 3-5 seconds, forming a microprism structure layer 23.

[0038] Step 3. Applying the upper protective layer 22: Cover the upper surface of the microprism structure layer 23 with the upper protective layer 22 (such as a transparent PET film), and use thermosetting adhesive, lamination or UV curing adhesive to make the upper protective layer 22 tightly adhere to the upper surface of the microprism structure layer 23 (that is, make the first right-angled face 2312 of the right-angled triangular prism unit 231 adhere to the lower surface of the upper protective layer 22), ensuring that there are no air bubbles.

[0039] Step 4. Coating Preparation and Coating: The weather-resistant resin matrix, first functional filler, second functional filler, and EVA resin are dispersed in a solvent at a predetermined mass ratio to form a uniform first weather-resistant transparent coating. The weather-resistant resin matrix, first functional filler, and second functional filler are also dispersed in a solvent at a predetermined mass ratio to form a uniform second weather-resistant transparent coating. The first and second weather-resistant transparent coatings are coated onto the upper surface of the upper protective layer 22 and the lower surface of the lower substrate layer 24, respectively. After drying and curing, a first weather-resistant transparent coating 21 and a second weather-resistant transparent coating 25 are formed, resulting in the composite film material.

[0040] Step 5. Slitting: The composite film is slitted according to the dimensions required by the photovoltaic module to obtain the photon gap enhancement film. For example... Figure 3 As shown, the size of the cut photon gap enhancement film 2 is adapted to the width and area of ​​the single gap region 42 of the solar cell 41 in the photovoltaic module (preferably, the width of the cut photon gap enhancement film 2 is equal to or slightly larger than the width of the single gap region 42 of the solar cell 41 in the photovoltaic module, and the length of the cut photon gap enhancement film 2 is preferably equal to the length of the single gap region 42 of the solar cell 41 in the photovoltaic module).

[0041] An application of the photon gap enhancement film of the present invention is described in [reference needed]. Figure 3-4During the lamination and encapsulation of photovoltaic modules, the pre-cut photon gap enhancement film 2 is laid between the upper cover plate 1 (such as photovoltaic glass) and the upper encapsulation film 3 (at this time, the first weather-resistant transparent coating 21 is in contact with the lower surface of the upper cover plate 1, and the second weather-resistant transparent coating 25 is in contact with the upper surface of the upper encapsulation film 3), or laid between the upper encapsulation film 3 and the battery string 4 (at this time, the first weather-resistant transparent coating 21 is in contact with the lower surface of the upper encapsulation film 3, and the second weather-resistant transparent coating 25 is in contact with the upper surface of the battery string 4); and ensuring that the inclined surface 2311 of the right-angled triangular prism unit 231 of the microprism structure layer 23 faces the direction of the gap region 42 of the battery cell 41. In practice, the battery string 4 includes a number of battery cells 41 arranged at intervals, and the side of the battery cell 41 has a gap region 42. The width of a single gap region 42 of the spaced-apart battery cells 41 is 0.1-1.5 mm. During installation, the extension direction of several right-angled triangular prism units 231 in the microprism structure layer 23 (i.e., the periodic arrangement direction of several right-angled triangular prism units 231, corresponding to the width direction of the microprism structure layer 23) must be adapted to the orientation of the gap region 42 of the solar cell 41 in the photovoltaic module (corresponding to the width direction of the gap region 42) (that is, the extension direction of several right-angled triangular prism units 231 is basically parallel to the orientation of the gap region 42 of the solar cell 41 in the photovoltaic module), and the microprism structure layer 23 of the photon gap enhancement film 2 is correspondingly set above the gap region 42 of the solar cell 41 (that is, a pre-cut photon gap enhancement film 2 is correspondingly set above each gap region 42) to achieve the best light refraction and guidance effect.

[0042] Therefore, a photovoltaic module of the present invention using a photon gap enhancement film 2 comprises, from top to bottom: an upper cover plate 1 (such as a photovoltaic front panel or photovoltaic glass), an upper encapsulating film 3, a cell string 4 (which includes a plurality of cells 41 arranged at intervals), a lower encapsulating film 5, and a lower cover plate 6 (such as a photovoltaic back panel or photovoltaic glass). The photovoltaic module also includes a plurality of photon gap enhancement films 2 arranged at intervals; the photon gap enhancement films 2 are disposed between the upper cover plate 1 and the upper encapsulating film 3, or between the upper encapsulating film 3 and the cell string 4; moreover, the width of each photon gap enhancement film 2 is equal to or slightly larger than the width of a single gap region 42 of a cell 41 in the photovoltaic module, and each photon gap enhancement film 2 is correspondingly disposed above a single gap region 42 of a cell 41.

[0043] Example 1 This embodiment provides a photonic gap enhancement film; see [link to relevant documentation]. Figure 1-2 It is a multi-layered composite structure, which includes, from top to bottom: a first weather-resistant transparent coating 21, an upper protective layer 22, a microprism structure layer 23, a lower substrate layer 24, and a second weather-resistant transparent coating 25.

[0044] The first weather-resistant transparent coating 21 is applied to the upper surface of the upper protective layer 22. The first weather-resistant transparent coating 21 comprises: a weather-resistant resin matrix (fluorinated acrylic resin), and a first functional filler (nano-silica with an average particle size of 400 nm, accounting for 6 wt% of the weather-resistant resin matrix mass), a second functional filler (NaA-type molecular sieve powder, an acetic acid adsorbent, accounting for 3 wt% of the weather-resistant resin matrix mass), and an ultraviolet absorber (BASF Tinuvin) dispersed in the weather-resistant resin matrix. The components include: 479 (2 wt% of the weather-resistant resin matrix), EVA resin dispersion (60 wt% of EVA resin in the dispersion, accounting for 15 wt% of the weather-resistant resin matrix), dispersant BYK9010 (0.1 wt% of the weather-resistant resin matrix), leveling agent BYK300 (0.2 wt% of the weather-resistant resin matrix), defoamer BYK052 (0.2 wt% of the weather-resistant resin matrix), and solvent (ethyl acetate, accounting for 15 wt% of the weather-resistant resin matrix). The thickness of the first weather-resistant transparent coating 21 is 12 micrometers.

[0045] The second weather-resistant transparent coating 25 is applied to the lower surface of the lower substrate layer 24. The second weather-resistant transparent coating 25 comprises: a weather-resistant resin matrix (fluorinated acrylic resin), and dispersed in the weather-resistant resin matrix are: a first functional filler (nano-silica with an average particle size of 400 nm, accounting for 3 wt% of the mass of the weather-resistant resin matrix), a second functional filler (NaA type molecular sieve powder, an acetic acid adsorbent, accounting for 5 wt% of the mass of the weather-resistant resin matrix), an ultraviolet absorber (BASF Tinuvin 479, accounting for 2 wt% of the mass of the weather-resistant resin matrix), a dispersant BYK9010 (0.1 wt% of the mass of the weather-resistant resin matrix), a leveling agent BYK300 (0.2 wt% of the mass of the weather-resistant resin matrix), a defoamer BYK052 (0.2 wt% of the mass of the weather-resistant resin matrix), and a solvent (ethyl acetate, accounting for 15 wt% of the mass of the weather-resistant resin matrix). The second weather-resistant transparent coating 25 has a thickness of 6 micrometers.

[0046] The upper protective layer 22 is a transparent PET film with a thickness of 30 micrometers. The lower surface of the upper protective layer 22 covers and adheres to the microprism structure layer 23.

[0047] The microprism structure layer 23 is a transparent layer, directly cured onto the upper surface of the lower substrate layer 24 using an acrylic UV adhesive through an imprinting process. The microprism structure layer 23 includes a number of periodically arranged right-angled triangular prism units 231. The first right-angled face 2312 of each right-angled triangular prism unit 231 is attached to the lower surface of the upper protective layer 22, while the second right-angled face 2313 of each right-angled triangular prism unit 231 is perpendicular to the upper surface of the lower substrate layer 24. The inclined surface 2311 of each right-angled triangular prism unit 231 serves as the light incident / refracting surface. The periodic spacing of the right-angled triangular prism units 231 is 100 micrometers, and the height of each right-angled triangular prism unit 231 is 100 micrometers. The base angle α of each right-angled triangular prism unit 231 (which is an isosceles right-angled triangular prism unit) is 45°.

[0048] The lower substrate layer 24 is a transparent PET film with a thickness of 50 micrometers.

[0049] The method for preparing a photon gap enhancement film according to this embodiment includes the following steps: Step 1. Provide a clean, transparent PET film (50 microns thick) as the lower substrate layer 24.

[0050] Step 2. A layer of acrylic UV adhesive is uniformly coated onto the upper surface of the lower substrate layer 24. A nickel mold with isosceles right-angled triangular grooves (the base angle α of the isosceles right-angled triangular prism unit is 45°, the periodic spacing is 100 micrometers, and the height is 100 micrometers) is used to roll and imprint the coated acrylic UV adhesive, while applying an energy of 3000 mw / cm². 2 Irradiation with a 395nm ultraviolet light source for 4s causes the acrylate UV adhesive to cure and form a microprism structure layer 23.

[0051] Step 3. A 30-micron-thick transparent PET film is used as the upper protective layer 22. After the lower surface of the film is coated with 3-micron-thick adhesive, it is laminated onto the upper surface of the cured microprism structure layer 23 by hot rolling (temperature 80℃, pressure 0.3MPa), so that the first right-angled face 2312 of the isosceles right-angled triangular prism unit of the microprism structure layer 23 is bonded to the lower surface of the upper protective layer 22, ensuring that there are no air bubbles.

[0052] Step 4. Preparation of the first weather-resistant transparent coating: Using fluorinated modified acrylic resin as the weather-resistant resin matrix, according to the raw material formula of the first weather-resistant transparent coating described in this embodiment, add the first functional filler, the second functional filler, the ultraviolet absorber, the EVA resin dispersion, the dispersant, the leveling agent, and the defoamer, and disperse them in the solvent; place them in a high-speed disperser and disperse continuously at 3000 r / min for 30 min, and filter them using a 250 mesh filter to obtain the first weather-resistant transparent coating.

[0053] Preparation of the second weather-resistant transparent coating: Using fluorinated modified acrylic resin as the weather-resistant resin matrix, according to the raw material formula of the second weather-resistant transparent coating described in this embodiment, add the first functional filler, the second functional filler, the ultraviolet light absorber, the dispersant, the leveling agent, and the defoamer, and disperse them in the solvent; place them in a high-speed disperser and disperse continuously at 3000 r / min for 30 min, and filter them with a 250 mesh filter to obtain the second weather-resistant transparent coating.

[0054] The first and second weather-resistant transparent coatings are coated onto the upper surface of the upper protective layer 22 and the lower surface of the lower substrate layer 24 respectively by microgravure coating. They are then cured in a 100°C oven for 2 minutes to form a 12-micron-thick first weather-resistant transparent coating 21 and a 6-micron-thick second weather-resistant transparent coating 25. The coatings are then wound up to obtain the composite film material (i.e., the semi-finished photon gap enhancement film).

[0055] Step 5. Slitting: Use a slitting machine to slit the semi-finished photon gap enhancement film into finished photon gap enhancement films with widths of 4mm, 6mm, and 15mm.

[0056] One type of photovoltaic module in this embodiment is shown below. Figure 3-4 The photovoltaic system is fabricated by laminating and framing the following components in the following order: upper cover plate 1 (photovoltaic glass), the finished photon gap enhancement film 2 (with the inclined surface 2311 of the isosceles right-angled triangular prism unit facing downwards; when laying the finished photon gap enhancement film 2, the extension direction of the isosceles right-angled triangular prism unit is parallel to the direction of the gap region 42 of the solar cell 41), upper encapsulating film 3 (EVA encapsulating film), solar cell string 4 (which includes 60 standard monocrystalline silicon solar cells (156mm×156mm)), lower encapsulating film 5 (EVA encapsulating film), and lower cover plate 6 (photovoltaic backsheet).

[0057] Comparative Example 1 This comparative example describes a photon gap enhancement film, its preparation method, and a photovoltaic module. Referring to Example 1, the difference between this example and Example 1 is: In the first weather-resistant transparent coating used to prepare the first weather-resistant transparent coating in this comparative example, the first functional filler is still nano-silica with an average particle size of 400nm, but the first functional filler accounts for only 2wt% of the mass of its weather-resistant resin matrix.

[0058] Comparative Example 2 This comparative example describes a photon gap enhancement film, its preparation method, and a photovoltaic module. Referring to Example 1, the difference between this example and Example 1 is: In the first weather-resistant transparent coating used to prepare the first weather-resistant transparent coating in this comparative example, the first functional filler is still nano-silica with an average particle size of 400nm, but the first functional filler accounts for only 10wt% of the mass of its weather-resistant resin matrix.

[0059] Comparative Example 3 This comparative example describes a photon gap enhancement film, its preparation method, and a photovoltaic module. Referring to Example 1, the difference between this example and Example 1 is: In the first weather-resistant transparent coating used to prepare the first weather-resistant transparent coating in this comparative example, the first functional filler still accounts for 6 wt% of the mass of its weather-resistant resin matrix, but the first functional filler is changed to nano-silica with an average particle size of 800 nm.

[0060] Comparative Example 4 The photovoltaic module of this comparative example differs from that of Example 1 in that the photovoltaic module of this example omits the photon gap enhancement film of Example 1; the photovoltaic module of this comparative example is laminated and framed in the following order: upper cover plate (photovoltaic glass), upper encapsulation film (EVA encapsulation film), cell string (which includes 60 standard monocrystalline silicon cells (156mm×156mm)), lower encapsulation film (EVA encapsulation film) and lower cover plate (photovoltaic backsheet).

[0061] Performance testing The transmittance of the photon gap enhancement films of Example 1 and Comparative Examples 1-3 was tested, and the electrical performance of the photovoltaic modules of Example 1 and Comparative Examples 1-4 was tested using a solar simulator (STC conditions: irradiance 1000 W / m², cell temperature 25°C, atmospheric mass AM1.5). The test results are shown in Table 1 below: Table 1

[0062] As shown in Table 1, compared to Comparative Example 4 (the control group, whose photovoltaic module does not contain a photon gap enhancement film), the photon gap enhancement film of Embodiment 1 of the present invention has higher light transmittance and significantly improves the power gain of the photovoltaic module. However, if the amount of the first functional filler added to the first weather-resistant transparent coating is too small (as in Comparative Example 1), or the amount of the first functional filler added is too large (as in Comparative Example 2), or the particle size of the first functional filler is too large (as in Comparative Example 3), the light transmittance of the photon gap enhancement film will decrease to varying degrees, and the power gain of the photovoltaic module will also decrease.

[0063] Furthermore, after conducting a 1000-hour dual 85°C / 85% relative humidity damp heat aging test on the photovoltaic modules of Example 1 and Comparative Example 4, the power degradation rate of the photovoltaic module of Example 1 was 0.3-0.5% lower than that of Comparative Example 4. Therefore, compared with Comparative Example 4 (which does not have a photon gap enhancement film in its photovoltaic module), the photovoltaic module of Example 1 of this invention, which uses a photon gap enhancement film, has better resistance to damp heat aging and can effectively reduce power degradation after damp heat aging.

[0064] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0065] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A photonic gap gain film, characterized in that, It has a multi-layered composite structure, which, from top to bottom, includes: a first weather-resistant transparent coating, an upper protective layer, a microprism structure layer, a lower substrate layer, and a second weather-resistant transparent coating. The microprism structure layer includes a number of periodically arranged right-angled triangular prism units, and the first right-angled face of the right-angled triangular prism unit is attached to the lower surface of the upper protective layer; The weather-resistant transparent coatings used in the first and second weather-resistant transparent coatings both include a weather-resistant resin matrix and functional fillers dispersed in the weather-resistant resin matrix; the functional fillers include a first functional filler and a second functional filler; the first functional filler is an optical conditioning filler, which accounts for 3-8 wt% of the mass of the weather-resistant resin matrix; the second functional filler is an acetic acid absorbing filler, which accounts for 2-5 wt% of the mass of the weather-resistant resin matrix.

2. The photonic gap enhancement film of claim 1, wherein, The periodic spacing of the right-angled triangular prism unit is 50-200 micrometers, the height of the right-angled triangular prism unit is 20-100 micrometers, and the base angle α of the right-angled triangular prism unit is 30°-60°.

3. The photonic gap enhancement film of claim 1 or 2, wherein, The right-angled triangular prism unit is formed on the upper surface of the lower substrate layer by imprinting and photocuring liquid photocuring resin material; the microprism structure layer is a transparent layer, the second right-angled face of its right-angled triangular prism unit is perpendicular to the upper surface of the lower substrate layer, and the inclined face of the right-angled triangular prism unit is a light refraction surface.

4. The photonic gap enhancement film of claim 1, wherein, The first functional filler is selected from one or more of nano-silica, nano-zirconia, and nano-alumina, and the particle size of the first functional filler is 100-500nm; The second functional filler is selected from one or more of alkali metal modified molecular sieves, metal-organic framework materials, and surface-modified activated alumina; The weather-resistant resin matrix is ​​at least one of fluorinated modified acrylic resin, polyurethane resin, or silicone resin.

5. The photonic gap enhancement film of claim 1 or 4, wherein, The weather-resistant transparent coating used in the first weather-resistant transparent coating also includes: 8-20 wt% EVA resin, which accounts for 8-20 wt% of the mass of its weather-resistant resin matrix, and 13-20 wt% additives, which account for 13-20 wt% of the mass of its weather-resistant resin matrix. The weather-resistant transparent coating used in the second weather-resistant transparent coating also includes: 13-20 wt% of additives according to the mass of its weather-resistant resin matrix; The additive is one or more of the following: ultraviolet light absorber, dispersant, leveling agent, defoamer, and solvent.

6. The photonic gap enhancement film of claim 1 or 4, wherein, The thickness of the first weather-resistant transparent coating is 10-15 micrometers; the thickness of the second weather-resistant transparent coating is 5-10 micrometers.

7. The photon gap enhancement film according to claim 1, characterized in that, The upper protective layer is a transparent PET film with a thickness of 20-50 micrometers; the lower substrate layer is a transparent PET film with a thickness of 20-80 micrometers; the total thickness of the photon gap enhancement film is controlled at 100-250 micrometers.

8. A method for preparing a photon gap enhancement film according to any one of claims 1-7, characterized in that, Includes the following steps: S1. A liquid photocurable resin material is coated on the upper surface of the lower substrate layer, and then molded and photocured by an imprinting mold to form a microprism structure layer. S2. Cover the upper protective layer with the upper surface of the microprism structure layer, so that the upper protective layer is in contact with the upper surface of the microprism structure layer. S3. Apply and cure the first weather-resistant transparent coating and the second weather-resistant transparent coating on the upper surface of the upper protective layer and the lower surface of the lower substrate layer, respectively.

9. A photovoltaic module, comprising, from top to bottom: The photovoltaic module comprises an upper cover plate, an upper encapsulating film, a battery string, a lower encapsulating film, and a lower cover plate. The battery string includes a plurality of battery cells arranged at intervals, with gap regions on the sides of the battery cells. The photovoltaic module further comprises a plurality of photon gap enhancement films arranged at intervals, wherein the photon gap enhancement film is a photon gap enhancement film as described in any one of claims 1-7. The photon gap enhancement film is disposed between the upper cover plate and the upper encapsulating film, or between the upper encapsulating film and the battery string. Each photon gap enhancement film covers the gap region of the corresponding battery cell.

10. A photovoltaic module according to claim 9, characterized in that, The periodic arrangement of several right-angled triangular prism units in the microprism structure layer is parallel to the width direction of the gap region between the solar cells in the photovoltaic module.

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