TWI462317B - Structure and fabricating method of a light-concentraing film applied to a solar panel - Google Patents

Description

Concentrating film applied to solar panel and manufacturing method thereof

The present invention relates to a concentrating film, and more particularly to a concentrating film suitable for use in a solar cell.

The solar power generation system can be mainly divided into two types, one is a Concentrating Photovoltaic System (CPV) using photoelectric conversion, and the other is a concentrated solar thermal power generation system (Concentrated Solar Thermal) using photothermal conversion. Power; CSP). The concentrating solar power generation system is a combination of a concentrating solar cell, an optical module, and a solar tracker, which uses a lens or a mirror to concentrate sunlight onto a solar cell, thereby reducing the area of the solar cell. In turn, the material cost is reduced, and the photoelectric conversion efficiency after concentrating will be higher than that of general solar irradiation.

In recent years, due to the rise of the solar photovoltaic industry, many different types of lenses or mirrors have also been tried on solar panels as concentrating elements to enhance the power generation efficiency of solar cells. For example, Fresnel lenses, parabolic mirrors or hemispherical lenses are all commonly used optical components.

There are many studies pointing out that microlens arrays have a positive impact on improving solar cell efficiency. For example, the optical film 10 having a microlens array shown in FIG. 1 is a microlens array comprising a plurality of hemispherical lenses 12. In addition, many documents also indicate that the appearance of the lens is also related to the improvement of performance. Therefore, the structural appearance of a common microlens may be a quadrangle or a hexagon.

Since the cost of solar cells is still difficult to reduce, solar cells can be provided if an optical component that can collect light at a wide angle can be designed. Higher light absorption or illumination values to further reduce the area of solar cells and their material costs, or increase their photoelectric conversion efficiency. If equipped with a solar tracker, it can increase its electricity production.

An object of the present invention is to provide a high-wide-angle concentrating element which is simple in process and has high concentrating efficiency.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

A method for fabricating a concentrating film according to an embodiment of the present invention, comprising: providing a substrate; forming a photoresist layer on the surface of the substrate; Applying a patterning step to the photoresist layer to define a photoresist pattern; applying a heat fusion step to the photoresist pattern to form the photoresist pattern to form a microstructure array; forming a concave mold on the microstructure array, The surface shape of the concave mold and the surface shape of the microstructure array can be matched; the concave mold is peeled off from the microstructure array; a first light transmissive material layer is formed on the concave mold; and the first light transmissive material layer is removed from the concave mold The upper light-transmissive material layer has an upper surface, a lower surface and two opposite sides, and the lower surface is located on the opposite side of the upper surface, wherein the structure of the upper surface is the same as the microstructure array; providing a cavity, the cavity Having an accommodating space, and fixing opposite sides of the first transparent material layer to the cavity, so that the lower surface faces the accommodating space, and the upper surface faces away from the accommodating space; and a second light transmissive material is Inject into the accommodating space until A light-transmitting material layer is deformed and lifted; and removing the second light transmissive material and the cavity accommodating space, the second light transmissive material accommodating space is formed above the first film and a converging light-transmitting material layer.

In an embodiment, the photoresist pattern includes a plurality of parallel lengths The strip pattern, the plurality of strip patterns are converted into a plurality of semi-cylinders via a hot melt step, and the plurality of semi-cylinders form a microstructure array. The step of forming a female mold on the microstructured array includes injecting a liquid poly-dimethylsiloxane (PDMS) material onto the microstructured array and curing it to form a female mold. In addition, the die can also be formed on the microstructure array by electroforming.

In one embodiment, the step of forming the first light transmissive material layer on the concave mold comprises: providing a liquid material having a light transmittance greater than 95%, such as polybismethyl decane; casting the liquid material And forming a first light transmissive material layer by drying the liquid material on the die to cure it.

In an embodiment, the step of providing the cavity includes: making the width of the accommodating space smaller than the distance between the opposite sides of the first transparent material layer; and opening a fluid injection pipe on the side of the accommodating space, the fluid injection pipe Throughout the outside of the cavity.

In one embodiment, the second light transmissive material is a liquid material having a light transmittance greater than 95%, such as polydimethyloxane.

A concentrating film according to an embodiment of the present invention is produced by the method described above and is suitably disposed on a solar panel. The concentrating film comprises a first light transmissive material layer and a second light transmissive material layer. The first light transmissive material layer has an upper surface and a lower surface, and the lower surface is on the opposite side of the upper surface. The upper surface has a plurality of microstructures, each microstructure having a width and a width on the order of microns. The second light transmissive material layer has a flat surface and a curved surface. The plane is located on the opposite side of the curved surface, and the curved surface has two opposite sides, and the two sides respectively intersect the plane, and the arc has a space between the plane and the plane, and the spacing gradually increases from the both sides toward the center. The lower surface of the first light transmissive material layer is attached to the second light transmissive layer On the arc surface of the material layer, the plane of the second light transmissive material layer is suitable for mounting on a solar panel.

In an embodiment, the first light transmissive material layer and the second light transmissive material layer are integrally formed.

In one embodiment, the first light transmissive material layer is different from the second light transmissive material layer, and both of the light transmittances are greater than 95%.

In one embodiment, the plurality of microstructures are a plurality of semi-cylindrical bodies arranged in parallel, and the materials of the first light transmissive material layer and the second light transmissive material layer both comprise polydimethyloxane.

The embodiment of the invention is characterized in that the concentrating film has a double-layer structure, which not only can make the direct light absorption efficiency high, but also can make the lateral light of other angles enter the double-layer concentrating film, and then the refracting is transmitted to the solar panel. It reduces the Fresnel loss at all angles and has a better light absorption effect than the prior art.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. The directional terms mentioned in the following embodiments, such as upper, lower, left, right, front or rear, etc., are only used to refer to the directions of the accompanying drawings. Therefore, the directional terms are used for illustration only and are not intended to limit the invention.

The invention relates to a high-wide-angle concentrating film which can be applied to a solar panel, in particular, when the incident direction of the light is 85°--85° (the direction when the light is directly irradiated to the solar panel is 0°), and the height is still high. Optical absorption efficiency of the concentrating film to enhance the function of collecting and tracking light in the solar power system.

As shown in FIG. 2A, this embodiment is a concentrating film 20, which is suitable for It is disposed above a solar panel 40. The concentrating film 20 includes a first light transmissive material layer 22 and a second light transmissive material layer 24. The first light transmissive material layer 22 is adhered to the second light transmissive material layer 24 .

As shown in FIG. 2B and FIG. 2C, the first light transmissive material layer 22 has an upper surface 221 and a lower surface 223, and the lower surface 223 is located on the opposite side of the upper surface 221. Upper surface 221 has a plurality of microstructures 222. In the present embodiment, the plurality of microstructures 222 are a plurality of parallel-arranged semi-cylinders, each semi-cylindrical system having a width W ₁ , and the width W ₁ is preferably on the order of micrometers. Each of the cylinders has at least one focus, and each of the focal points is located above the light receiving surface of the solar panel 40. The semi-cylinder can receive sunlight from a plurality of different directions, whether it is parallel or perpendicular to the solar panel 40.

The second light transmissive material layer 24 has a flat surface 241 and a curved surface 243. The plane 241 is located on the opposite side of the curved surface 243. The curved surface 243 has two opposite side edges 242, 244. The two side edges 242, 244 are respectively intersected with the plane 241, and the arc surface 243 has a spacing H from the plane 241. _{1. The} pitch H ₁ gradually increases from the both sides 242, 244 toward the center. The lower surface 223 of the first transparent material layer 22 is attached to the curved surface 243 of the second transparent material layer 24, and the plane 241 of the second transparent material layer 24 is suitable for being mounted on the solar panel 40. .

In an embodiment, the first light transmissive material layer 22 and the second light transmissive material layer 24 are integrally formed. The first light transmissive material layer 22 and the second light transmissive material layer 24 are made of a material having a light transmittance of more than 95%, for example, poly-dimethylsiloxane (PDMS). The first light transmissive material layer 22 and the second light transmissive material layer 24 may be made of the same or different materials, for example, the transmittance of both may be greater than 95%, or both materials include polydimethylene. Oxygen alkyl.

3A to 3K are schematic views showing a method of manufacturing a concentrating film according to an embodiment of the present invention, and the steps are as follows:

(1) Coating photoresist: As shown in FIG. 3A, a substrate 30 is placed on a spin-coater, and an appropriate amount of photoresist 32 is dropped thereon, and the coating machine is rotated. The resulting centrifugal force causes the photoresist 32 to be uniformly applied to the surface of the substrate 30 to form a photoresist layer 32A as shown in Fig. 3B, and the thickness thereof is controlled by the number of revolutions. In this embodiment, the AZ4620 positive photoresist is selected, and the selection condition is that the system has good mechanical properties such as hardness and tensile strength, and can be made into a high-thickness structure.

(II) Exposure: As shown in Fig. 3B, the commonly used exposure modes of the lithography process can be divided into three types: contact type, proximity type and projection type. In this embodiment, the contact exposure method is selected, and exposure is performed by using an exposure machine, and a mask 34 having a plurality of rectangular patterns is used as a blocking light.

(3) Development: As shown in Fig. 3C, the main purpose of development is to form an array of photoresist patterns 36 defined after exposure, such as a plurality of mutually parallel strip patterns 32a as shown in Fig. 3C. , displayed on the substrate 30.

(4) Thermal reflow: as shown in Fig. 3D, after high-temperature heating for hot-melting, the plurality of elongated strip patterns 32a can be melted into a plurality of parallel-arranged semi-cylindrical bodies 32b, which form a micro Structure array 38.

(5) Pour in PDMS and Lift off: As shown in FIG. 3E to FIG. 3F, PDMS is then poured onto the microstructure array 38, and the microstructure array 38 is peeled off using acetone to make a concave shape. Mold 39. Therefore, the surface shape of the female mold 39 and the surface shape of the microstructure array 38 can be matched to each other. In addition, concave The mold 39 can also be formed on the microstructure array 38 by electroforming.

(6) Casting liquid poly-dimethylsiloxane (PDMS): As shown in FIG. 3G, after the concave mold 39 is formed, the first light-transmitting material, for example, PDMS, is first cast into the concave mold. Mold 39. Since the PDMS is a liquid colloid having fluidity before curing, the present embodiment mainly forms a microstructure 222 like the upper surface 221 of the first light transmissive material layer 22 by casting. Next, as shown in Fig. 3H, after the liquid PDMS cast on the female mold 39 is dried and cured and the female mold 39 is removed, a single-layer thin film lens 22a is formed. In the present embodiment, both the female mold 39 and the thin film lens 22a are made of PDMS. The film lens 22a has an upper surface, a lower surface, and opposite sides, and the lower surface is on the opposite side of the upper surface, wherein the structure of the upper surface is the same as the microstructure array 38.

(7) Injecting the liquid PDMS into the cavity 37: as shown in FIG. 3I, a cavity 37 is provided. The C-C cross-section of FIG. 3I is shown in FIG. 3J, and the cavity 37 has an accommodation space 371 therein. A fluid injection pipe 372 is formed on one side of the accommodating space 371, and the fluid injection pipe 372 is passed through one side wall of the cavity 37. After the completed PDMS film lens 22a is placed over the cavity 37, the left and right sides of the film lens 22a are fixed to the left and right side edges of the cavity 37, and baffles 35a and 35b are respectively attached to the front and rear sides of the film lens 22a. Next, a second light transmissive material 24a, such as a PDMS material, is injected into the cavity 37 via the fluid injection conduit 372 until the PDMS film lens 22a is deformed to swell.

When the film lens 22a is placed over the cavity 37, the lower surface of the film lens 22a faces the accommodating space 371, and the upper surface thereof faces the accommodating space 371. In the present embodiment, the width W ₂ of the accommodating space 371 is preferably smaller than the distance D _{2 of the} opposite sides of the film lens 22a. The opening of the fluid injection pipe 372 may be provided at the center of one of the side walls of the cavity 37 such that the liquid second light transmissive material 24a is uniformly dispersed in the cavity 37.

In the present embodiment, the surfaces of the shutters 35a and 35b facing one side of the cavity are each provided with a blocking block 352a and 352b. The blocking blocks 352a and 352b are curved strip structures projecting from the surfaces of the baffles 35a and 35b. During the deformation and bulging of the film lens 22a, the shutters 35a and 35b prevent the liquid second light-transmitting material 24a from overflowing from the front and rear sides of the cavity 37, and the film lens 22a cannot be continuously supported up. As shown in FIG. 3K, in addition to preventing the second light transmissive material 24a from overflowing, the blocking blocks 352a and 352b can also be used as a deformation stop position of the film lens 22a to prevent excessive deformation of the film lens 22a, thereby defining a condensed light. The final appearance of the film 20a. For example, the line connecting each of the microstructure vertices on the film lens 22a will approximately conform to the shape of the blocking blocks 352a and 352b.

The deformed structure of the PDMS film lens 22a will be like the first light transmissive material layer 22 shown in Figs. 2A to 2C. Finally, as shown in FIG. 3K, the second light transmissive material 24a in the cavity 37 and the accommodating space 371, and a portion of the first light transmissive material layer 22 fixed to the edge of the cavity 37 are removed (the portion below the broken line L) The second light-transmitting material 24a and the first light-transmitting material layer 22a above the space 371 (the portion above the broken line L) form the light-concentrating film 20a of the present invention.

In the embodiment shown in Figs. 2A to 2C and 3K, there is no space between each of the semi-cylindrical surfaces on the upper surfaces of the first light-transmitting material layers 22 and 22a of the light-concentrating films 20 and 20a. However, if the photoresist pattern is slightly adjusted so that each of the two elongated strip patterns 32a shown in FIG. 3C forms a pitch, the light-concentrating film 20b as shown in FIG. 4 will be finally produced, and each half thereof. The cylinders have a spacing D _{3 between them} .

In an embodiment, the baffles 35a and 35b have a side cross-sectional shape of the light-concentrating film 20, 20a or 20b to be formed. In the steps shown in FIGS. 3I to 3K, when the first light transmissive material layer 22 or the film lens 22a is continuously supported from the bottom to the top by the second light transmissive material 24a until the predetermined light collecting film side sectional shape is satisfied Then, the second light transmissive material 24a can be stopped.

As shown in FIG. 5, it is an optical simulation result of the average illumination value of sunlight at different incident angles when the concentrating film of the present embodiment is applied to a solar panel. The horizontal axis of Fig. 5 is the incident angle, the unit is "degree", and the incident angle when the sun is directly defined is 0 degrees; the vertical axis is the average illumination value, and the unit is "W/m ² ". Simulating with a two-layer microlens structured concentrating film by an optical software under the same set parameters and conditions for a single layer parallel long cylindrical microlens (as shown in Fig. 3H) equivalent to the conventional technique ( As shown in FIG. 2A, the results shown in FIG. 5 can be obtained. It is found from the figure that the average illuminating value of the concentrating film of the present invention at 0° to 85° is significantly higher than that of the single layer parallel long columnar microlens. Therefore, it is understood that the light-concentrating film of the embodiment of the present invention not only has a high light absorption rate under direct light, but also enhances the absorption efficiency of the solar panel 40 for lateral light.

In summary, the present invention proposes a new process method, which is made of a concentrating film which is suitable for being mounted on a solar panel (light panel), and can be lighted at 85° to -85° (at 0°). High light absorption efficiency is achieved when light is directed at the direction of the solar panel. The invention is characterized in that the double-layer concentrating film not only can make the direct light absorption efficiency high, but also can make the lateral light of other angles enter the double-layer concentrating film, and then the refracting is transmitted to the solar panel, so that the angles are Fresnel's loss is reduced, and it has better light absorption than the general design. It should be further noted that in the above specific embodiment, the bottom surface 241 is a double layer of a rectangle. The lens is exemplified, but it can be understood by those skilled in the art that the size and shape of the first light transmissive material layer and the second light transmissive material layer can be changed and designed according to actual needs, and thus the present invention protects The scope is not limited to the specific examples described above.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

10‧‧‧Preventional optical film

12‧‧‧hemispherical lens

20, 20a, 20b‧‧‧ concentrating film

D ₃ ‧‧‧The spacing between the semi-cylindrical bodies of the concentrating film 20b

22‧‧‧First light transmissive material layer

22a‧‧‧film lens

D ₂ ‧‧‧Distance of the opposite sides of the film lens

221‧‧‧The upper surface of the first light transmissive material layer

222‧‧‧Microstructure of the first light transmissive material layer

W ₁ ‧‧‧The width of the semi-cylindrical layer of the first light transmissive material layer

223‧‧‧The lower surface of the first light transmissive material layer

24‧‧‧Second light transmissive material layer

24a‧‧‧Second light-transmitting material

241‧‧‧The plane of the second layer of light transmissive material

243‧‧‧The curved surface of the second layer of light transmissive material

242, 244‧‧‧ sides of the curved surface

H ₁ ‧‧‧ spacing between the curved surface and the plane

30‧‧‧Substrate

32‧‧‧Light resistance

32A‧‧‧ photoresist layer

32a‧‧‧ long strip pattern

32b‧‧‧Semi-cylinder formed by photoresist material

34‧‧‧Photomask

35a, 35b‧‧ ‧ baffle

36‧‧‧resist pattern

37‧‧‧ cavity

371‧‧‧ accommodating space of the cavity

372‧‧‧ fluid injection pipeline

W ₂ ‧‧‧ Width of the accommodation space

38‧‧‧Microstructure Array

39‧‧‧ concave die

40‧‧‧ solar panels

1 is a schematic view of an optical film having a microlens array.

2A to 2C are schematic views of a light collecting film according to an embodiment of the present invention.

3A to 3K are schematic views showing a method of manufacturing a light-concentrating film according to an embodiment of the present invention.

4 is a schematic view of a light collecting film according to another embodiment of the present invention.

Figure 5 is an optical simulation result of the average illumination value of the concentrating film of an embodiment of the present invention at different light incident angles.

20‧‧‧Concentrating film

22‧‧‧First light transmissive material layer

221‧‧‧The upper surface of the first light transmissive material layer

222‧‧‧Microstructure of the first light transmissive material layer

223‧‧‧The lower surface of the first light transmissive material layer

24‧‧‧Second light transmissive material layer

241‧‧‧The plane of the second layer of light transmissive material

243‧‧‧The curved surface of the second layer of light transmissive material

242, 244‧‧‧ sides of the curved surface

40‧‧‧ solar panels

Claims (8)

A method for fabricating a concentrating film, comprising: providing a substrate; forming a photoresist layer on a surface of the substrate; applying a patterning step to the photoresist layer to define a photoresist pattern; The resist pattern is subjected to a hot melting step to form the photoresist pattern into a microstructure array; a concave mold is formed on the microstructure array, so that the surface shape of the concave mold and the surface shape of the microstructure array can match each other Stripping the die from the microstructure array; forming a first light transmissive material layer on the die; peeling the first light transmissive material layer from the die, wherein the first light transmissive material layer Having an upper surface, a lower surface and opposite sides, the lower surface is located on the opposite side of the upper surface, wherein the upper surface has the same structure as the microstructure array; and a cavity is provided, the cavity has a receiving space And fixing the opposite sides of the first light transmissive material layer to the cavity such that the lower surface faces the accommodating space, and the upper surface faces away from the accommodating space; Injecting the light material into the accommodating space until the first light transmissive material The layer is deformed and embossed; and the second light transmissive material in the accommodating space is removed, and the second light transmissive material above the accommodating space forms a condensed light with the first light transmissive material layer film. The method of manufacturing a concentrating film according to claim 1, wherein the photoresist pattern comprises a plurality of mutually parallel strip-shaped patterns, and the plurality of strip-shaped patterns are converted into a plurality of half by the hot-melting step. a cylinder, the plurality of semi-cylinders forming the microstructure array, and the step of forming the die on the microstructure array comprises: pouring a liquid poly-dimethylsiloxane (PDMS) material into the liquid The microstructure is formed on the microstructure array to be cured. The method for producing a concentrating film according to claim 1, wherein the step of forming the first light transmissive material layer on the concave mold comprises: providing a liquid material having a light transmittance greater than 95%; A material is cast on the die; and the liquid material on the die is dried to cure to form the first layer of light transmissive material. The method for producing a concentrating film according to claim 1, wherein the step of forming the first light transmissive material layer on the concave mold comprises: providing a liquid polydimethyl methoxy siloxane material; A polybismethyl siloxane material is cast on the die; and the polybismethyl siloxane material on the die is dried to cure to form the first light transmissive material layer. The method for manufacturing a concentrating film according to claim 1, wherein the step of providing the cavity comprises: making a width of the accommodating space smaller than a distance between the opposite sides of the first transparent material layer; A fluid injection pipe is opened on one side of the accommodating space, and the fluid injection pipe penetrates to the outside of the cavity. The method for producing a light-concentrating film according to claim 5, wherein the second light-transmitting material is a liquid polydimethylsiloxane. The method for manufacturing a concentrating film according to claim 1, wherein the step of providing the cavity comprises: providing two baffles, and respectively arranging the baffles on upper edges of opposite sidewalls of the cavity And corresponding to the other two opposite sides of the first light transmissive material layer. The method of manufacturing a concentrating film according to claim 7, wherein the step of providing the cavity comprises: providing a blocking block on a side surface of each of the baffles facing the cavity, and using the blocking The shape of the block defines the appearance of the concentrating film.