Back contact solar cell

Abstract

The invention relates to a back contact solar cell which comprises a semiconductor substrate and a passivation anti-reflection film, the backlight surface of the semiconductor substrate is provided with a doped region, and the doped region is provided with a tunneling oxide layer and a doped layer arranged on the side, away from the semiconductor substrate, of the tunneling oxide layer. The passivation anti-reflection film comprises a first passivation anti-reflection film arranged on the side, away from the tunneling oxide layer, of the doping layer, the doping area is provided with a tower-footing-shaped texture structure, the tower-footing-shaped texture structure comprises a top face, a bottom face and a side wall connected between the top face and the bottom face, and the thickness of the first passivation anti-reflection film on the top face and the bottom face is larger than the thickness of the first passivation anti-reflection film on the side wall. The thickness of the passivation anti-reflection film at the doped region of the backlight surface is customized, and the thickness of the passivation anti-reflection film on the top surface and the bottom surface is larger than that of the passivation anti-reflection film on the side wall based on the composition of different crystal faces on the top surface, the bottom surface and the side wall of the tower footing-shaped texture structure, so that different passivation and anti-reflection requirements on the doped region are met.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a back-contact solar cell. Background Technology

[0002] In the fabrication of back-contact solar cells, different types of doped regions need to be formed on the back side of the semiconductor substrate to achieve the core electrical functions of the cell. To avoid signal interference between different doped regions, each doped region is usually physically isolated by an isolation region.

[0003] To ensure light absorption efficiency, the surface of the doped region typically exhibits a tower-like textured structure. However, this structure exhibits significant morphological variations, with the top, sidewalls, and bottom requiring different parameters for the passivation and antireflection film. Current conventional passivation processes often employ a single material system and fabrication parameters, which cannot meet the diverse passivation and antireflection requirements of the doped region on the back side of the substrate. Summary of the Invention

[0004] Therefore, it is necessary to provide a back-contact solar cell with optimized and improved passivation and antireflection film to meet the different passivation and antireflection requirements of different parts of the back-side doped region.

[0005] This application provides a back-contact solar cell, including a semiconductor substrate and a passivation antireflection film. The back surface of the semiconductor substrate has a doped region. The doped region has a tunneling oxide layer and a doped layer disposed on the side of the tunneling oxide layer away from the semiconductor substrate. The passivation antireflection film includes a first passivation antireflection film disposed on the side of the doped layer away from the tunneling oxide layer. The doped region has a tower-like textured structure. The tower-like textured structure includes a top surface, a bottom surface, and a sidewall connecting the top surface and the bottom surface. The thickness of the first passivation antireflection film on the top surface and the bottom surface is greater than the thickness of the sidewall.

[0006] It is understandable that the passivation and antireflection film thickness of the doped region on the backlight is customized, and the passivation and antireflection film thickness of the sidewall of the tower-like texture structure is configured to be smaller than that of the top and bottom surfaces, so as to take into account the different passivation and antireflection requirements of different parts of the doped region.

[0007] In one embodiment, the thickness of the first passivation antireflection film is 70 nm to 110 nm, and the refractive index is 2.0 to 2.2.

[0008] In one embodiment, the doped regions are provided in a plurality of manner, the backlight surface has an isolation region for isolating adjacent doped regions, and the passivation antireflection film further includes a second passivation antireflection film disposed in the isolation region.

[0009] In one embodiment, the thickness of the second passivation antireflection film is 40 nm to 70 nm, and the refractive index is 2.1 to 2.4.

[0010] In one embodiment, the thickness of the second passivation antireflection film at the bottom of the isolation region is d1, and the thickness of the second passivation antireflection film at the side of the isolation region is d2, where 1 < d1 / d2 < 2.

[0011] In one embodiment, the bottom of the isolation area has multiple pyramid-shaped textured structures, each pyramid-shaped textured structure including a conical surface, and the portion between adjacent pyramid-shaped textured structures is a substrate. The thickness of the second passivation antireflection film on the conical surface is less than the thickness on the substrate.

[0012] In one embodiment, the thickness of the first passivation antireflection film is D1, the thickness of the second passivation antireflection film is D2, and 1 < D1 / D2 < 3; the refractive index of the first passivation antireflection film is n1, the refractive index of the second passivation antireflection film is n2, and 1 < n2 / n1 < 1.3.

[0013] In one embodiment, the passivation antireflection film further includes a third passivation antireflection film disposed on the light-facing surface of the semiconductor substrate, the third passivation antireflection film having a thickness of 65nm~90nm and a refractive index of 1.9~2.1;

[0014] The thickness of the first passivation antireflection film is D1, and the thickness of the third passivation antireflection film is D3, where 1 < D1 / D3 < 2; the refractive index of the first passivation antireflection film is n1, and the refractive index of the third passivation antireflection film is n3, where 1 < n1 / n3 < 1.5.

[0015] In one embodiment, the semiconductor substrate has a side surface connecting the light-facing surface and the back-light-reflecting surface, and the passivation antireflection film further includes a fourth passivation antireflection film disposed on the side surface, the fourth passivation antireflection film having a thickness of 100nm~160nm and a refractive index of 2.0~2.1.

[0016] The thickness of the first passivation antireflection film is D1, the thickness of the third passivation antireflection film is D3, and the thickness of the fourth passivation antireflection film is D4, where 0.5 < D4 / (D1+D3) < 1.

[0017] In one embodiment, the refractive index and thickness of the passivation antireflection film at any location satisfy: 80≤n×d≤350;

[0018] Where n is the refractive index of the passivation antireflection film, and d is the thickness of the passivation antireflection film, in nm.

[0019] Compared with the prior art, the back contact solar cell provided in this application customizes the thickness of the passivation and antireflection film in the doped region of the back light surface. Based on the different crystal planes on the top, bottom and sidewalls of the tower-like textured structure, the thickness of the passivation and antireflection film on the top and bottom surfaces is greater than the thickness of the passivation and antireflection film on the sidewalls, so as to meet the different passivation and antireflection requirements in the doped region. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the passivation and antireflection film structure of a back-contact solar cell according to an embodiment of this application;

[0022] Figure 2 This is a microscopic schematic diagram of the passivation and antireflection film structure at the doped region of a back-contact solar cell according to an embodiment of this application;

[0023] Figure 3 The graph shows the relationship between the thickness of the passivation antireflection film and the passivation effect under the same refractive index, where the passivation effect is characterized by the ideal open-circuit voltage (ivoc).

[0024] Figure 4 The graph shows the relationship between the refractive index of the passivation antireflection film and the passivation effect under the same thickness condition, where the passivation effect is characterized by the ideal open-circuit voltage (ivoc).

[0025] Figure 5 for Figure 1 A magnified view of a portion of point A in the middle;

[0026] Figure 6 This is an electron microscope image of the bottom of the isolation region of a back-contact solar cell according to an embodiment of this application, wherein the bright part is the passivation antireflection film.

[0027] Reference numerals: 10, semiconductor substrate; 11, light-facing surface; 12, backlight-facing surface; 121, doped region; 122, isolation region; 123, top surface; 124, bottom surface; 125, sidewall; 126, conical surface; 127, substrate; 128, bottom; 129, side edge; 13, side surface; 20, tunneling oxide layer; 30, doped layer; 40, first passivation antireflection film; 50, second passivation antireflection film; 60, third passivation antireflection film; 70, fourth passivation antireflection film; 80, electrode; 80a, positive electrode; 80b, negative electrode. Detailed Implementation

[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0029] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," "side," "top," "bottom," and similar expressions used in this application's specification are merely for describing various exemplary structural parts and elements of this application. However, their use herein is for illustrative purposes only and is determined based on the exemplary orientations shown in the accompanying drawings, and does not represent the only possible implementation. Since the embodiments disclosed in this application can be arranged in different orientations, these terms indicating orientation are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] It should be noted that "axial arrangement" means that the overall arrangement direction is along the axial direction, including but not limited to axial extension, and may be at an angle to the axial direction.

[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0034] In the field of solar cells, the main function of passivation antireflection films is to passivate and reduce reflection. Generally, passivation antireflection films can be composed of one or more materials such as silicon oxide, aluminum oxide, silicon nitride, silicon carbide, and silicon oxynitride, and are prepared by methods such as PECVD (plasma-enhanced chemical vapor deposition) and LPECVD (low-pressure electron cyclotron resonance plasma-enhanced chemical vapor deposition).

[0035] For solar cells, light utilization is mainly concentrated in the mid-to-long wavelength range, and the thickness of the passivation antireflection film determines the wavelength of absorbed light. Specifically, for passivation antireflection films made of silicon nitride, a thickness of 77nm~93nm primarily absorbs mid-to-long wavelength light, matching the light utilization efficiency of the solar cell. Furthermore, within a certain thickness range, a higher thickness results in better passivation. However, as the thickness of the passivation antireflection film increases and exceeds 90nm, further increases in thickness lead to a smaller improvement in passivation effect. Additionally, excessively thick passivation antireflection films result in poorer light utilization, decreased film thickness uniformity, and a corresponding increase in production costs. Of course, the actual application thickness of the passivation antireflection film is selected based on specific requirements.

[0036] Furthermore, considering that increasing the thickness of the passivation antireflection film within a certain range will improve the passivation effect but decrease the antireflection effect, the passivation effect will be significantly reduced. Different areas on the doped region of the back contact solar cell have varying requirements for passivation antireflection performance, and traditional passivation processes using a single-thickness passivation antireflection film cannot simultaneously meet the different passivation antireflection needs of the doped regions. Please refer to [link / reference]. Figures 1 to 6 To address this issue, this application provides a back-contact solar cell. The thickness and refractive index of the passivation and antireflection film are customized for different parts of the doped region 121 of the back surface 12. The refractive index is adjusted under a suitable passivation and antireflection film thickness to balance passivation and antireflection effects and improve cell conversion efficiency.

[0037] Specifically, see Figure 1This application provides a back-contact solar cell, including a semiconductor substrate 10 and a passivation antireflection film. The semiconductor substrate 10 has a light-facing surface 11 and a back-facing surface 12, and the back-facing surface 12 of the semiconductor substrate 10 has a doped region 121. It is understood that an electrode 80 needs to be disposed on the doped region 121. Specifically, the doped region 121 includes a P-region doped region for disposing of a positive electrode 80a and an N-region doped region for disposing of a negative electrode 80b, with at least one P-region and one N-region doped region. For example, in... Figure 1 In the embodiment shown, four doped regions 121 are provided, two of which are P-region doped regions and the other two are N-region doped regions. The doped regions 121 are provided with a tunneling oxide layer 20 and a doped layer 30 disposed on the side of the tunneling oxide layer 20 away from the semiconductor substrate 10. The passivation antireflection film includes a first passivation antireflection film 40 disposed on the side of the doped layer 30 away from the tunneling oxide layer 20.

[0038] See Figure 2 For the doped region 121, it has a tower-like textured structure, which includes a top surface 123, a bottom surface 124 and a sidewall 125 connecting the top surface 123 and the bottom surface 124. The thickness of the first passivation antireflection film 40 in the top surface 123 and the bottom surface 124 is greater than the thickness in the sidewall 125.

[0039] Specifically, the tower-like textured structure has multiple tower bases. The sidewall 125 of the tower base is mainly composed of crystal planes with a crystal plane index of (111), while the top surface 123 and bottom surface 124 contain crystal planes with crystal plane indices of (111), (110), and (100). Among them, the (111) crystal plane has low chemical activity and is easy to combine with hydrogen to form saturated dangling bonds, reducing the interface state density. The (111) crystal plane is one of the crystal planes with the highest atomic density in face-centered cubic crystals (such as silicon). Its surface atoms are closely arranged and have high symmetry. The closely arranged atoms make the surface form a more stable chemical bond structure, with lower surface energy, and more uniform bonding with the cross section of the passivation antireflection film. In addition, this structure reduces cross section defects, so that a thinner passivation antireflection film can form a continuous and dense protective layer without the need for additional thickness to compensate for the incompleteness of the interface.

[0040] Moreover, the core function of the passivation antireflection film is to cancel reflection through light interference. Its thickness design is related to the wavelength of light, the refractive index of the film layer, and the refractive index of the crystal plane. That is, the atomic arrangement of the (111) crystal plane makes the surface refractive index present a specific distribution, which can match the refractive index of the passivation antireflection film material better. This matching reduces the reflection coefficient of light at the interface. Therefore, the sidewall 125 only needs a thinner film layer than the top surface 123 and the bottom surface 124 to achieve the same or equivalent antireflection effect as other crystal planes (such as the (100) crystal plane). At the same time, a thinner film layer can reduce production costs to a certain extent.

[0041] It should also be noted that the passivation and antireflection film structures on the top surface 123 and bottom surface 124 of the tower base structure can remain identical. However, due to the actual deposition process, the passivation and antireflection film on the top surface 123 will be thicker than that on the bottom surface 124, and the thickness of the passivation and antireflection film on the sidewall 125 will be 0.5 to 0.8 times the thickness of the passivation and antireflection film on the top surface 123 / bottom surface 124. Of course, in the actual deposition process, if the passivation and antireflection film on the bottom surface 124 is thicker than that on the top surface 123, it also meets the design requirement that the passivation and antireflection film on the sidewall 125 must be thinner than that on the top surface 123 and bottom surface 124.

[0042] In some preferred embodiments of this application, the thickness of the first passivation antireflection film 40 is 70 nm to 110 nm, and the refractive index is 2.0 to 2.2. Specifically, the thickness of the first passivation antireflection film 40 can be 70 nm, 80 nm, 90 nm, 100 nm, or 110 nm, and the refractive index can be 2.0, 2.1, or 2.2. See also Figure 3 and Figure 4 Specifically, the passivation effect is characterized by the ivoc (ideal open-circuit voltage) of the passivation antireflection film, representing the relationship between the passivation effect and the thickness and refractive index of the passivation antireflection film. When the thickness and refractive index of the first passivation antireflection film 40 are within the above-mentioned range, the function of the first passivation antireflection film 40 is mainly passivation, reducing contact resistance. This customized first passivation antireflection film 40 can better balance chemical passivation and field-effect passivation, ensuring excellent passivation and antireflection effects throughout the entire doped region 121 while meeting the passivation and antireflection requirements at different locations in the doped region 121.

[0043] In the field of solar cells, chemical passivation refers to repairing or covering defects on the cell surface using chemical means to directly reduce the carrier recombination rate at the defect sites. Its core principle is "eliminating recombination centers." The working principle involves depositing thin films or performing chemical treatments to allow atoms in the passivation layer of the antireflective coating to combine with suspended components and impurity defects on the cell surface, filling defect sites and thus reducing carrier recombination at those locations. Field-effect passivation, on the other hand, creates a built-in electric field on the cell surface / interface, using electromagnetic force to "drive away" carriers and indirectly prevent them from reaching defects for recombination. Its core principle is "isolating carriers from recombination centers." The working principle is that there are charges between the passivation layer of the antireflective coating and the cell substrate. These charges induce a built-in electric field on the substrate surface. This electric field repels some carriers and attracts others, preventing carriers from accumulating at surface defects and thus reducing recombination.

[0044] In some embodiments of this application, see Figure 1The doped regions 121 are provided in multiple ways, and the backlight surface 12 has an isolation region 122 for isolating adjacent doped regions 121. The passivation antireflection film also includes a second passivation antireflection film 50 disposed in the isolation region 122. The second passivation antireflection film 50 is provided to block leakage current channels and maintain high barrier properties.

[0045] In addition, although the area between the outermost doped region 121 and the edge of the backlight surface 12 is not used to isolate the two adjacent doped regions 121, it is still covered by the same second passivation antireflection film 50 as the isolation region 122.

[0046] Preferably, the thickness of the second passivation antireflection film 50 is 40 nm to 70 nm, and the refractive index is 2.1 to 2.4. Specifically, the thickness of the second passivation antireflection film 50 can be 40 nm, 50 nm, 60 nm, or 70 nm, and the refractive index can be 2.1, 2.2, 2.3, or 2.4. A high refractive index configuration can enhance compactness, block lateral diffusion of charge carriers, and increase the hydrogen content at the contact interface, resulting in a superior passivation effect.

[0047] For quarantine zone 122, see [link / reference] Figure 1 and Figure 5 The isolation region 122 is recessed on the back side of the semiconductor substrate 10 and has a bottom 128 and a side 129 for physically isolating adjacent doped regions 121. In some embodiments of this application, the thickness of the second passivation antireflection film 50 at the bottom 128 of the isolation region 122 is d1, and the thickness of the second passivation antireflection film 50 at the side 129 of the isolation region 122 is d2, satisfying: 1 < d1 / d2 < 2. This configuration ensures the passivation and antireflection effect of the isolation region 122 while reducing production costs. Specifically, the roughness of the side 129 of the isolation region 122 is greater than the roughness of the bottom 128. Between the side 129 and the bottom 128, if the thickness of the passivation antireflection film at the bottom 128 is used as a reference, a thinner passivation antireflection film at the side 129 of the isolation region 122 than at the bottom 128 can achieve a better passivation effect, that is, satisfying 1 < d1 / d2. Meanwhile, a thinner passivation and antireflection film on the side 129 can also reduce production costs. Of course, the thickness of the passivation and antireflection film on the side 129 of the isolation region 122 cannot be too thin, that is, it needs to satisfy d1 / d2<2 to ensure the passivation effect.

[0048] Additionally, see Figure 6In terms of microstructure, the bottom 128 of the isolation region 122 has multiple pyramid-shaped textured structures, including conical surfaces 126. The area between adjacent pyramid-shaped textured structures is the substrate 127. The thickness of the second passivation antireflection film 50 on the conical surface 126 is less than its thickness on the substrate 127. Specifically, the pyramid-shaped textured structure at the bottom 128 of the isolation region 122 has a large bottom surface area and good light-trapping effect, but there are many gaps between the pyramids. Furthermore, the non-pyramid portions of the semiconductor substrate 10 also typically have many gaps, indicating more recombination centers. This requires more hydrogen to neutralize the dangling bonds on the substrate surface, reducing the surface recombination rate.

[0049] Specifically, in the pyramid-shaped texture structure, there are multiple pyramids, each with a cone face 126 and a apex. It can be understood that the apex is essentially the vertex where the cone faces 126 intersect. Both the cone face 126 and the apex are crystal planes with a crystal plane index of (111), while the base 127 between adjacent pyramids has crystal planes with crystal plane indices of (111), (110), and (100). There are many voids and defects, and the recombination is large, requiring a thicker passivation and antireflection film than the cone face 126 to handle the defects.

[0050] In some preferred embodiments of this application, the thickness of the first passivation antireflection film 40 is D1, and the thickness of the second passivation antireflection film 50 is D2, where 1 < D1 / D2 < 3. The refractive index of the first passivation antireflection film 40 is n1, and the refractive index of the second passivation antireflection film 50 is n2, where 1 < n2 / n1 < 1.3. The doped region 121 has a pyramidal texture structure, and the bottom 128 of the isolation region 122 has a pyramidal texture structure. The roughness of the doped region 121 is less than the roughness of the bottom 128 of the isolation region 122. Therefore, a thinner passivation antireflection film with a higher refractive index than that in the doped region 121 is used in the isolation region 122 to improve passivation.

[0051] In some embodiments of this application, the passivation antireflection film includes a third passivation antireflection film 60 disposed on the light-facing surface 11 of the semiconductor substrate 10. The thickness of the third passivation antireflection film 60 is 65nm~90nm, and the refractive index is 1.9~2.1. Specifically, the thickness can be 65nm, 80nm, or 90nm, and the refractive index can be 1.9, 2.0, or 2.1. The light-facing surface 11 of the semiconductor substrate 10 is the main light-absorbing surface. With the third passivation antireflection film 60 configured in this way, it is beneficial to absorb short-wavelength light (blue wave) light. Chemical passivation is the main method, and the film has a high hydrogen content, which can effectively saturate the dangling bonds on the silicon wafer surface and reduce the interface state density. It should be noted that as the refractive index increases, although the passivation effect is better, the light absorption effect will deteriorate. Therefore, for the light-facing surface 11, the refractive index of the third passivation antireflection film 60 is controlled in the range of 1.9~2.1 to meet the light absorption requirements. For other parts of the film, such as the first passivation antireflection film 40 and the second passivation antireflection film 50 on the backlight surface 12, the impact on light absorption is small. Therefore, the refractive index of other parts can be controlled above 2.0, so that a good passivation effect can be achieved with a thinner thickness, thereby reducing costs.

[0052] In a further embodiment, the thickness of the first passivation antireflection film 40 is D1, and the thickness of the third passivation antireflection film 60 is D3, where 1 < D1 / D3 < 2. The refractive index of the first passivation antireflection film 40 is n1, and the refractive index of the third passivation antireflection film 60 is n3, where 1 < n1 / n3 < 1.5. Specifically, the backlight surface 12 has low light absorption, so battery performance can be improved by enhancing passivation. Therefore, the thickness of the first passivation antireflection film 40 in the doped region 121 of the backlight surface 12 can be configured to be greater than the thickness of the third passivation antireflection film 60 on the light-facing surface 11. Similarly, the refractive index of the first passivation antireflection film 40 is configured to be greater than the refractive index of the third passivation antireflection film 60.

[0053] It is important to note that when 2 < D1 / D3 and 1.5 < n1 / n3, the improvement in passivation and antireflection effects is relatively small. Specifically, if the thickness and refractive index of the third passivation antireflection film 60 are used as a benchmark, and the thickness of the first passivation antireflection film 40 is more than twice that of the third passivation antireflection film 60, and its refractive index is more than 1.5 times that of the third passivation antireflection film 60, the production cost of the first passivation antireflection film 40 increases, but the improvement in passivation and antireflection effects is not significant. Therefore, keeping the thickness and refractive index of the first passivation antireflection film 40 within the range of D1 / D3 < 2 and n1 / n3 < 1.5 can meet the passivation and antireflection requirements while also reducing production costs to some extent.

[0054] In some embodiments of this application, the semiconductor substrate 10 has a side surface 13 connecting the light-facing surface 11 and the backlight surface 12. The passivation antireflection film further includes a fourth passivation antireflection film 70 disposed on the side surface 13. The thickness of the fourth passivation antireflection film 70 is 100 nm to 160 nm, and the refractive index is 2.0 to 2.1. Specifically, the thickness can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, or 160 nm, and the refractive index can be 2.0, 2.05, or 2.1.

[0055] The fourth passivation antireflective film 70 on side 13 effectively covers the texture structure of side 13 of the semiconductor substrate 10, providing comprehensive passivation to the semiconductor substrate 10. Furthermore, the first passivation antireflective film 40 has a thickness of D1, the third passivation antireflective film 60 has a thickness of D3, and the fourth passivation antireflective film 70 has a thickness of D4, where 0.5 < D4 / (D1+D3) < 1. This configuration of the thickness and refractive index of the fourth passivation antireflective film 70 provides edge passivation and protection while controlling the cost of the passivation antireflective film.

[0056] In some embodiments of this application, the refractive index and thickness of the passivation antireflection film at any location satisfy the following condition: 80 ≤ n × d ≤ 350. Here, n is the refractive index of the passivation antireflection film, and d is the thickness of the passivation antireflection film, both in nm. Specifically, 80 ≤ n × d ≤ 350 means that the product of the refractive index and thickness of the passivation antireflection film is in the range of 80 to 350.

[0057] Specifically, this application provides the following embodiment.

[0058] The third passivation antireflective coating 60 on the light-facing surface 11 has a thickness of 80 nm and a refractive index of 2.0. This optimizes the antireflection effect in the blue light band and releases hydrogen atoms through silicon-hydrogen bonds (Si-H bonds) to neutralize surface dangling bonds during sintering.

[0059] The fourth passivation antireflective film 70 on side 13 has a thickness of 130 nm and a refractive index of 2.05. This effectively covers the side texture and improves the edge passivation of the semiconductor substrate 10.

[0060] The first passivation antireflection film 40 on the doped region 121 of the backlight surface 12 has a thickness of 90 nm and a refractive index of 2.1. The second passivation antireflection film 50 on the isolation region 122 has a thickness of 50 nm and a refractive index of 2.3. The high refractive index of the second passivation antireflection film 50 on the isolation region 122 releases more hydrogen atoms at the bottom of the pyramid (the porous region), reducing the surface recombination rate. Furthermore, the high refractive index enhances compactness, blocks leakage channels, and maintains high barrier properties.

[0061] Under the constraint of “80≤n×d≤350”, by matching and combining the passivation and antireflection films of various parts of the semiconductor substrate 10, the light-facing surface 11 is low in reflection, the isolation region 122 of the back-facing surface 12 is highly passivated, and the leakage current blocking effect of the isolation region 122 is achieved.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A back-contact solar cell, comprising a semiconductor substrate and a passivation antireflection film, wherein the back surface of the semiconductor substrate has a doped region, the doped region having a tunneling oxide layer and a doped layer disposed on the side of the tunneling oxide layer away from the semiconductor substrate, characterized in that, The passivation antireflection film includes a first passivation antireflection film disposed on the side of the doped layer away from the tunneling oxide layer. The doped region has a tower-like texture structure, which includes a top surface, a bottom surface, and a sidewall connecting the top surface and the bottom surface. The thickness of the first passivation antireflection film on the top surface and the bottom surface is greater than the thickness on the sidewall.

2. The back-contact solar cell according to claim 1, characterized in that, The thickness of the first passivation antireflection film is 70nm~110nm, and the refractive index is 2.0~2.

2.

3. The back-contact solar cell according to claim 1, characterized in that, The doped regions are provided in multiple ways, the backlight surface has an isolation region for isolating adjacent doped regions, and the passivation antireflection film also includes a second passivation antireflection film disposed in the isolation region.

4. The back-contact solar cell according to claim 3, characterized in that, The thickness of the second passivation antireflection film is 40nm~70nm, and the refractive index is 2.1~2.

4.

5. The back-contact solar cell according to claim 3, characterized in that, The thickness of the second passivation antireflection film at the bottom of the isolation region is d1, and the thickness of the second passivation antireflection film at the side of the isolation region is d2, where 1 < d1 / d2 < 2.

6. The back-contact solar cell according to claim 3, characterized in that, The bottom of the isolation area has multiple pyramid-shaped textured structures, each pyramid-shaped textured structure including a conical surface. The portion between adjacent pyramid-shaped textured structures is a substrate, and the thickness of the second passivation antireflection film on the conical surface is less than the thickness on the substrate.

7. The back-contact solar cell according to claim 3, characterized in that, The thickness of the first passivation antireflection film is D1, the thickness of the second passivation antireflection film is D2, and 1 < D1 / D2 < 3; the refractive index of the first passivation antireflection film is n1, the refractive index of the second passivation antireflection film is n2, and 1 < n2 / n1 < 1.

3.

8. The back-contact solar cell according to claim 1, characterized in that, The passivation antireflection film further includes a third passivation antireflection film disposed on the light-facing surface of the semiconductor substrate, the thickness of the third passivation antireflection film being 65nm~90nm and the refractive index being 1.9~2.1; The thickness of the first passivation antireflection film is D1, and the thickness of the third passivation antireflection film is D3, where 1 < D1 / D3 < 2; the refractive index of the first passivation antireflection film is n1, and the refractive index of the third passivation antireflection film is n3, where 1 < n1 / n3 < 1.

5.

9. The back-contact solar cell according to claim 8, characterized in that, The semiconductor substrate has a side surface connecting the light-facing surface and the back-light-reflecting surface. The passivation antireflection film further includes a fourth passivation antireflection film disposed on the side surface. The thickness of the fourth passivation antireflection film is 100nm~160nm, and the refractive index is 2.0~2.

1. The thickness of the first passivation antireflection film is D1, the thickness of the third passivation antireflection film is D3, and the thickness of the fourth passivation antireflection film is D4, where 0.5 < D4 / (D1+D3) < 1.

10. The back-contact solar cell according to any one of claims 1 to 9, characterized in that, The refractive index and thickness of the passivation antireflection film at any location satisfy: 80≤n×d≤350; Where n is the refractive index of the passivation antireflection film, and d is the thickness of the passivation antireflection film, in nm.

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