Solar cell structure and manufacturing method thereof

Abstract

This invention belongs to the field of solar cell technology, and particularly relates to a solar cell structure and manufacturing method. The solar cell structure, from top to bottom, includes a structural antireflection layer, a transition antireflection layer, and a cell layer. The structural antireflection layer has a refractive index close to that of air within the operating frequency band of the cell layer, with a refractive index n1 between 1.2 and 1.5. The upper part of the structural antireflection layer is a periodically distributed arched structure. The radius r of the circle corresponding to the outer boundary arc of the arch is greater than the maximum wavelength of the operating frequency band. The half-angle corresponding to the arc is set as α, typically selected between 20° and 40°. The chord length corresponding to the arc is D. The material layer thickness at the bottom of the arched structure is c1. The bottom of the coating is a hollow prismatic structure with an isosceles triangle cross-section and a base length d, where d = 0.9 × D. The base angle reading of the triangle is between 45° and 60°, and its apex angle is vertically positioned between two adjacent arched structures on the top layer. The hollow prismatic structure is filled with an opaque material.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a solar cell structure and manufacturing method. Background Technology

[0002] Currently, energy development faces serious challenges such as ever-increasing demand and deteriorating ecological environment, making sustainable green energy a global focus. Solar cells are one of the main ways to obtain clean energy from the sun, and any improvement in the power generation efficiency of solar cells will bring significant economic benefits.

[0003] Research on solar cells mainly includes the development and improvement of semiconductor materials, the configuration of solar modules, and the design of antireflection layers. The design of antireflection layers involves adding two or three coating layers to the top of the cell without altering its structure. By selecting the properties of these coatings or designing micro / nano structures on them, the reflection of external sunlight is reduced, allowing more light to enter the solar cell and thus improving power generation efficiency. On one hand, since air has a refractive index of 1, while the refractive index of the top layer material of the solar cell is much higher than that of air, typically between 2 and 3, it is difficult to achieve a good reflection reduction effect with just two or three antireflection layers. On the other hand, the design of the antireflection film aims to achieve a gradual change in refractive index from the air layer to the top layer of the cell, minimizing the refractive index difference between adjacent layers, thereby reducing reflection. Under the premise of a gradual refractive index, the reflection of sunlight entering the cell can be reduced. Since solar cells also have a multi-layered structure, there is also reflection between the internal layers. The design of the antireflection structure, while reducing the reflection of light entering the cell from the outside, also allows light reflected from inside the cell to easily escape and enter the outside. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a solar cell structure and manufacturing method. Through structural design and material selection, the invention achieves bidirectional heterogeneity, allowing light incident perpendicularly from the outside of the cell to easily enter the cell with very low reflectivity. Simultaneously, light reflected back from the inside of the cell can be reflected back into the cell with high reflectivity. In other words, light easily enters the cell but does not easily escape, thereby improving cell performance.

[0005] Specifically, the present invention provides a solar cell structure based on the material properties of each layer, which is characterized by:

[0006] From top to bottom, it includes a structural anti-reflection layer, a transition anti-reflection layer, and a battery layer;

[0007] The refractive index n1 of the antireflective layer is 1.2 to 1.5. The upper part of the antireflective layer is a periodically distributed arched structure. The radius r of the circle corresponding to the outer boundary arc of the arch is greater than the maximum wavelength of the working frequency band. The half angle corresponding to the arc is set as α, which is selected from 20° to 40°. The chord length corresponding to the arc is D = 2rsin(α). The thickness of the material layer at the bottom of the arched structure is: in The bottom of the anti-reflective layer is a hollow prismatic structure with an isosceles triangle cross-section. The length of the base of the triangle is d = 0.9 × D. The base angle of the triangle is 45° to 60°, and its apex is located vertically between two adjacent arched structures on the top layer. The hollow prismatic structure is filled with opaque material.

[0008] Preferably, the antireflective layer of the above structure is made of ethylene-tetrafluoroethylene copolymer (ETFE) material with a refractive index of about 1.39.

[0009] Preferably, the half-angle α corresponding to the aforementioned arc is 30°.

[0010] Preferably, the aforementioned opaque material has a high reflectivity, enabling complete reflection of sunlight within the operating frequency band.

[0011] Preferably, the opaque material is polytetrafluoroethylene (ETFE).

[0012] Preferably, the refractive index of the transition antireflection layer is slightly greater than that of the structural antireflection layer within the solar frequency range in which the battery operates.

[0013] Preferably, when the antireflective layer n1≈1.39, a plastic film POE with a refractive index of about 1.48 can be used.

[0014] Preferably, the battery layer can be any type of solar cell, such as crystalline silicon cells, gallium arsenide cells, triple-junction gallium arsenide cells, etc., and the cells used do not require an anti-reflection layer.

[0015] In addition, the present invention also proposes a method for fabricating the antireflection layer of the above-mentioned solar cell structure, which is characterized by including the following steps:

[0016] Step 1): The upper part of the antireflection layer is set as a periodically distributed arched structure, and the radius r of the circle corresponding to the outer boundary arc of the arch is greater than the maximum wavelength of the working frequency band.

[0017] Step 2): The half angle corresponding to the outer boundary arc of the arch is set as α, usually 20° to 40°, and the chord length corresponding to the arc is D = 2rsin(α);

[0018] Step 3): Set the material layer thickness c1 at the bottom of the arch structure. in

[0019] Step 4): The bottom of the structural anti-reflection layer is set as a hollow prismatic structure with an isosceles triangle cross section. The length of the base of the triangle is d = 0.9 × D. The base angle of the triangle is 45° to 60°, and its apex is vertically positioned between two adjacent arched structures on the top layer.

[0020] Step 5): Fill the hollow prismatic structure with an opaque material.

[0021] Preferably, the half-angle α corresponding to the outer boundary arc of the arch is 30°.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The solar cell structure provided by this invention achieves bidirectional heterogeneity through its structural design and material selection. This allows light incident perpendicularly from the outside of the cell to easily enter the cell with very low reflectivity. At the same time, light reflected back from inside the cell can be reflected back into the cell with high reflectivity. In other words, light can easily enter the cell but is not easy to escape, thereby improving the cell's performance. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the solar cell structure proposed in this invention;

[0025] Figure 2 The solar cell structure proposed in this invention is a three-dimensional view;

[0026] Figure 3 This is a schematic diagram illustrating the design process of the antireflection layer in the solar cell structure proposed in this invention.

[0027] Figure 4 This describes the light propagation process within a solar cell structure.

[0028] Figure 5 This is the main energy transfer process in a solar cell structure;

[0029] Figure 6 This describes the propagation process of reflected light within the cell of a solar cell structure.

[0030] Reference numerals: 1. Structural antireflective layer, 2. Opaque material, 3. Transition antireflective layer, 4. Battery layer. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the following embodiments.

[0032] See Figure 1 and Figure 2This invention proposes a solar cell structure, which, from top to bottom, includes a structural antireflection layer 1, a transition antireflection layer 2, and a cell layer 4.

[0033] See Figure 3 The refractive index n1 of the antireflection layer 1 is 1.2 to 1.5. The upper part of the antireflection layer 1 is a periodically distributed arched structure. The radius r of the circle corresponding to the outer boundary arc of the arch is greater than the maximum wavelength of the working frequency band. The half angle corresponding to the arc is set as α, and α is selected as 20° to 40°. The chord length corresponding to the arc is D = 2rsin(α). The thickness of the material layer at the bottom of the arched structure is: in The bottom of the anti-reflective layer 1 is a hollow prismatic structure with an isosceles triangle cross-section. The length of the base of the triangle is d = 0.9 × D. The base angle of the triangle is 45° to 60°, and its apex is located between two adjacent arched structures on the top layer. The hollow prismatic structure is filled with an opaque material 2.

[0034] Preferably, the antireflective layer 1 of the above structure is made of ethylene-tetrafluoroethylene copolymer (ETFE) material with a refractive index of about 1.39.

[0035] Preferably, the half-angle α corresponding to the aforementioned arc is 30°.

[0036] Preferably, the opaque material 2 has a high reflectivity, which enables complete reflection of sunlight within the operating frequency band.

[0037] Preferably, the opaque material 2 is polytetrafluoroethylene (ETFE).

[0038] Preferably, the refractive index of the transition antireflection layer 2 is slightly greater than that of the structural antireflection layer 1 within the solar frequency range in which the battery operates.

[0039] Preferably, when the antireflective layer 1n1≈1.39, a plastic film POE with a refractive index of about 1.48 can be selected.

[0040] Preferably, the battery layer 4 can be any type of solar cell, such as crystalline silicon cells, gallium arsenide cells, triple-junction gallium arsenide cells, etc., and the cells used do not require an anti-reflection layer.

[0041] Additionally, see Figure 3 The present invention also proposes a method for fabricating the antireflection layer 1 of the above-mentioned solar cell structure, comprising the following steps:

[0042] Step 1): The upper part of the antireflection layer 1 is set as a periodically distributed arched structure. The radius r of the circle corresponding to the outer boundary arc of the arch is greater than the maximum wavelength of the working frequency band. The specific value is determined by the processing cost and coating thickness. When a smaller nanoscale is selected, the processing cost is higher, but the required coating thickness is relatively thinner. When the radius of the circle is increased, the processing cost is reduced, but the required coating thickness will increase.

[0043] Step 2): The half-angle corresponding to the outer boundary arc of the arch is set as α, usually 20° to 40°. Figure 3 In (a), α≈30°, the chord length corresponding to the arc is D=2rsin(α); since the refractive index of the antireflection layer 1 is close to that of air, the outermost layer can be guaranteed to have a low reflectivity.

[0044] Step 3): Set the material layer thickness c1 at the bottom of the arch structure, such as... Figure 3 As shown in (b), it is only necessary to calculate the intersection point of the incident light ray at the edge of the arc and the incident light ray at the middle of the arc, such as... Figure 3 As shown in (c), according to the law of refraction sin(α)×1=sin(β)×n1, we can obtain At the same time, for the right triangle formed by the half-chord length and the coating thickness, there exists Therefore, it can be calculated that...

[0045] Step 4): The bottom of the anti-reflection layer 1 is set as a hollow prismatic structure, with the cross-section of the prismatic shape being an isosceles triangle, such as... Figure 3 As shown in (d), the length of the base of the triangle is d = 0.9 × D, so that for parallel incident light, the light passing through the slit is 0.1 times the total light, ensuring that most of the light hits the opaque structure; the base angle of the triangle is 45° to 60°, and its apex is vertically positioned between the two adjacent arched structures on the top layer.

[0046] Step 5): Fill the hollow prismatic structure with opaque material 2.

[0047] like Figure 4 As shown, we use a strength of 1000 W / m 3 Taking light as an example, the colors in the diagram represent the logarithm of the intensity. Since the battery surface has a periodic structure, to facilitate light identification, a light beam with a width equal to the period is selected to enter the battery. Figure 4 (a) The figure shows light rays incident vertically downwards onto the battery from the outside; Figure 4 (b) The figure shows that a portion of the reflection is formed on the outer surface of the anti-reflection layer 1 of the battery structure. The incident light beam converges under the action of the surface structure and bypasses the opaque structure to reach the transition anti-reflection layer 2. Figure 4 (c) The figure shows that the light rays form two beams, one reflected and one transmitted, in the transition antireflection layer 2. Due to the small change in refractive index, the reflected light energy is less. Figure 4 (d) The figure shows light entering the battery layer 4 from the transition antireflection layer 2, and some of the light is reflected back to the transition antireflection layer 2; Figure 4 (e) Figure shows that the light reflected from the transition antireflection layer 2 to the battery layer 4 will reach the surface of the opaque structure and be reflected back to the battery layer 4. Figure 4 Figure (f) shows that due to the presence of the opaque structure, light is continuously reflected inside the transition antireflection layer 2 and eventually enters the battery.

[0048] To facilitate observation of the energy propagation process, we discarded light rays with lower energy and selected light rays with an energy logarithm greater than 1.5. Their propagation process is as follows: Figure 5 As shown, energy enters the antireflection layer 1 from the outside and is continuously reflected inside the transition antireflection layer 2 before finally entering the battery. Only some energy is reflected out through the gaps between the opaque structures.

[0049] To examine the propagation process of the outgoing wave formed by internal reflection of the battery, we present... Figure 6 The simulation shown depicts light entering the transition antireflection layer 2 from inside the battery, as... Figure 6 (a) Figure 6 As shown in (b), after multiple reflections, only a small portion of the light escapes through the gaps between the opaque structures, while the rest is reflected back into the battery.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A solar cell structure, characterized in that: From top to bottom, it includes a structural anti-reflection layer, a transition anti-reflection layer, and a battery layer; The refractive index of the antireflective layer of the structure The radius is 1.2~1.

5. The upper part of the anti-reflection layer is a periodically distributed arched structure, and the radius of the outer arc of the arch corresponds to the radius of the circle. The value is greater than the maximum wavelength of the operating frequency band, and the half-angle corresponding to the arc is set to... , The angle is selected as 20°~40°, and the chord length corresponding to the arc is... The thickness of the material layer at the bottom of the arched structure is: ,in The bottom of the anti-reflective layer is a hollow prismatic structure with an isosceles triangle cross-section, and the length of the base of the triangle is... The base angle of the triangle is 45°~60°, and its apex is located vertically between two adjacent arched structures at the top level. The hollow prismatic structure is filled with an opaque material.

2. The solar cell structure according to claim 1, characterized in that: The antireflective layer of the structure is made of ethylene-tetrafluoroethylene copolymer (ETFE).

3. A solar cell structure according to claim 2, characterized in that: The half angle corresponding to the arc It is 30°.

4. A solar cell structure according to claim 3, characterized in that: The opaque material can completely reflect sunlight within the operating frequency band.

5. A solar cell structure according to claim 4, characterized in that: The opaque material is polytetrafluoroethylene (ETFE).

6. The solar cell structure according to claim 5, characterized in that: The transition antireflection layer has a higher refractive index than the structural antireflection layer within the solar frequency range in which the battery operates.

7. The solar cell structure according to claim 1, characterized in that: The battery layer is a crystalline silicon battery or a gallium arsenide battery.

8. A method for fabricating an antireflection layer in a solar cell structure according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1): The upper part of the anti-reflection layer is set as a periodically distributed arched structure, with the outer boundary arc of the arch corresponding to the radius of the circle. The value should be greater than the maximum wavelength of the operating frequency band; Step 2): Set the half-angle corresponding to the outer boundary arc of the arch to... The arc is between 20° and 40°, and the chord length corresponding to the arc is... ; Step 3): Set the thickness of the material layer at the bottom of the arch structure. , ,in ; Step 4): The bottom of the anti-reflection layer is set as a hollow prismatic structure with an isosceles triangle cross-section, and the length of the base of the triangle is... The base angle of the triangle is 45°~60°, and its apex is located vertically between two adjacent arched structures at the top level. Step 5): Fill the hollow prismatic structure with an opaque material.

9. The method for fabricating a structural anti-reflection layer according to claim 8, characterized in that: The half angle corresponding to the arc of the outer boundary circle is 30°.

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