Solar cell and photovoltaic module

Abstract

The utility model relates to a solar cell and a photovoltaic assembly. The solar cell comprises a silicon substrate which is provided with a first surface and a second surface which are opposite to each other; the first passivation layer, the P-type doping layer and the first transparent conductive oxide layer are sequentially stacked on the first surface, the first passivation layer is a silicon dioxide layer, and the P-type doping layer is a nickel oxide layer; the second passivation layer, the N-type doped layer and the second transparent conductive oxide layer are sequentially stacked on the second surface. The solar cell has high photoelectric conversion efficiency.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, and in particular to solar cells and photovoltaic modules. Background Technology

[0002] Existing heterojunction (HJT) solar cells suffer from poor spectral response in the short wavelength range, high loss of short-wavelength high-energy photons, high transmission of longer-wavelength photons, and problems such as ultraviolet-induced degradation (UVID) and dark degradation, resulting in low photoelectric conversion efficiency. Utility Model Content

[0003] Therefore, it is necessary to provide a solar cell and photovoltaic module that have high photoelectric conversion efficiency to address the above problems.

[0004] A solar cell, the solar cell comprising:

[0005] A silicon substrate having opposing first and second surfaces;

[0006] A first passivation layer, a P-type doped layer, and a first transparent conductive oxide layer are sequentially stacked on the first surface, wherein the first passivation layer is a silicon dioxide layer and the P-type doped layer is a nickel oxide layer;

[0007] A second passivation layer, an N-type doped layer, and a second transparent conductive oxide layer are sequentially stacked on the second surface.

[0008] In one embodiment, the thickness of the first passivation layer is 1nm-5nm;

[0009] And / or, the thickness of the P-type doped layer is 2nm-10nm.

[0010] In one embodiment, the N-type doped layer is an N-type doped zinc oxide layer.

[0011] In one embodiment, the thickness of the N-type doped layer is 8 nm-22 nm.

[0012] In one embodiment, the second passivation layer is a silicon dioxide layer.

[0013] In one embodiment, the thickness of the second passivation layer is 1 nm to 8 nm.

[0014] In one embodiment, the first surface is a velvety surface, and the second surface is a polished surface or a velvety surface.

[0015] In one embodiment, the thickness of the first transparent conductive oxide layer is 60nm-80nm;

[0016] And / or, the thickness of the second transparent conductive oxide layer is 50nm-70nm.

[0017] In one embodiment, the first surface is the light-receiving surface, and the second surface is the backlight surface.

[0018] A photovoltaic module includes a solar cell as described above.

[0019] In this novel solar cell, by setting a silicon dioxide layer as a passivation layer between the silicon substrate and the P-type doped layer, and using a nickel oxide layer as the P-type doped layer, ultraviolet-induced degradation and dark degradation can be largely avoided. This effectively reduces surface reflection, lowers surface recombination rate and recombination loss, improves carrier lifetime, and enhances the separation of photogenerated electron-hole pairs, thereby improving the overall performance of the solar cell. This results in a solar cell with high external quantum efficiency, short-wavelength range (ultraviolet region) spectral response, low long-wavelength (near-infrared region) photon transmission, and avoidance of ultraviolet-induced degradation and dark degradation problems, thus giving the solar cell high photoelectric conversion efficiency. Attached Figure Description

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

[0021] Figure 1 A schematic diagram of the structure of a solar cell according to one embodiment of the present invention;

[0022] Figure 2 The graphs show the external quantum response test results of the solar cells of Embodiment 1, Comparative Example 1 and Comparative Example 2 provided by this utility model in different wavelength ranges. In the graphs, A represents Embodiment 1, B represents Comparative Example 1, and C represents Comparative Example 2.

[0023] Figure 3 The graph shows the reflectivity test results of the solar cells of Embodiment 1, Comparative Example 1 and Comparative Example 2 in different wavelength ranges provided for this utility model. In the graph, A represents Embodiment 1, B represents Comparative Example 1 and C represents Comparative Example 2.

[0024] Figure label:

[0025] 1. Silicon substrate; 2. First passivation layer; 3. P-type doped layer; 4. First transparent conductive oxide layer; 5. Second passivation layer; 6. N-type doped layer; 7. Second transparent conductive oxide layer; 8. First metal electrode; 9. Second metal electrode. Detailed Implementation

[0026] To facilitate understanding of this utility model, it will be described in more detail below. However, it should be understood that this utility model can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of this utility model more thorough and complete.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0028] like Figure 1 The diagram shown is a structural schematic of a solar cell according to an embodiment of the present invention. The solar cell includes: a silicon substrate 1 having a first surface and a second surface opposite to each other; a first passivation layer 2, a P-type doped layer 3 and a first transparent conductive oxide layer 4 sequentially stacked on the first surface; and a second passivation layer 5, an N-type doped layer 6 and a second transparent conductive oxide layer 7 sequentially stacked on the second surface.

[0029] Traditional silicon heterojunction solar cells are prone to ultraviolet-induced degradation (UVID) due to the presence of hydrogen atoms at the interface between the intrinsically hydrogenated amorphous silicon layer and the crystalline silicon layer. Therefore, under sunlight, hydrogen atoms are excited and diffuse into the silicon substrate, generating defects such as dangling bonds and hydrogen vacancies. These defects trap charge carriers, thereby reducing charge carrier lifetime and consequently reducing the cell efficiency.

[0030] In contrast, nickel oxide (NiOx)-based solar cells are less susceptible to UV-induced degradation due to the lack of hydrogen in their structure. Furthermore, NiOx exhibits chemical stability and resistance to environmental degradation, contributing to the long-term stability of solar cells. Moreover, compared to doped amorphous silicon, NiOx has a wider band gap and higher electron affinity, reducing the recombination of photogenerated carriers and improving the overall efficiency of the cell. Finally, NiOx is also a low-cost material, making its application in solar cells highly attractive.

[0031] In addition, traditional silicon heterojunction solar cells also undergo dark degradation under the influence of ultraviolet light. Dark degradation is usually related to hydrogenation of hydrogen atoms in the intrinsic amorphous silicon layer. These hydrogen atoms can migrate under dark conditions and lead to the formation of defects, such as dangling bonds.

[0032] Studies have found that silicon dioxide (SiO2), because it does not contain hydrogen (H), can eliminate the source of the above-mentioned defects and reduce dark degradation. At the same time, silicon dioxide has chemical stability and is not easy to form defects. This stability helps to maintain the interface between silicon substrate 1 (crystalline silicon layer) and silicon dioxide, further limiting degradation over time.

[0033] Therefore, in this invention, the first passivation layer 2 is a silicon dioxide layer, and the P-type doped layer 3 is a nickel oxide layer.

[0034] In this invention, a silicon dioxide layer is used as a passivation layer on the surface of the silicon substrate 1. Utilizing the properties of silicon dioxide, it can essentially avoid dark degradation caused by ultraviolet light, effectively reduce the surface recombination rate, and improve carrier lifetime. At the same time, it can minimize surface reflection and improve light capture, thereby improving light absorption and the overall electrical performance of the device. Meanwhile, a nickel oxide layer is used as a p-type doped layer 3, which can avoid ultraviolet-induced degradation. Utilizing the inherent properties of nickel oxide, it can form selective contacts for carriers that facilitate hole transport but block electron transport, thereby helping to reduce recombination losses and enhancing the separation of photogenerated electron-hole pairs, resulting in higher photoelectric conversion efficiency of the battery.

[0035] Therefore, in this invention, by setting a silicon dioxide layer as a passivation layer between the silicon substrate 1 and the P-type doped layer 3, and using a nickel oxide layer as the P-type doped layer 3, ultraviolet-induced degradation and dark degradation can be largely avoided. At the same time, surface reflection can be effectively reduced, surface recombination rate and recombination loss can be reduced, carrier lifetime can be improved, and the separation of photogenerated electron-hole pairs can be strengthened. This improves the overall stability and electrical performance of the solar cell, enabling the solar cell to achieve higher external quantum efficiency, spectral response in the short wavelength range (ultraviolet region), lower transmission of long wavelength (near-infrared region) photons, and largely avoid the problems of ultraviolet-induced degradation and dark degradation, thereby making the solar cell have higher photoelectric conversion efficiency.

[0036] In one embodiment, the silicon substrate 1 is selected from an n-type single-crystal silicon wafer or a p-type single-crystal silicon wafer, preferably an n-type single-crystal silicon wafer (c-silicon wafer).

[0037] Furthermore, the resistivity of the silicon substrate 1 is 1 Ω·cm-5 Ω·cm, and its thickness is 95 μm-150 μm. <100> Orientation, area > 120cm² 2 The preferred size is 220cm. 2 .

[0038] In one embodiment, the thickness of the first passivation layer 2 is 1 nm to 5 nm. It can be understood that the thickness of the first passivation layer 2 can be selected from any value between 1 nm and 5 nm. Specifically, the thickness of the first passivation layer 2 includes, but is not limited to, 1 nm, 2 nm, 3 nm, 4 nm, and 5 nm.

[0039] It should be noted that the first passivation layer 2 in this invention can be deposited using techniques such as atomic layer deposition (ALD), plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), thermal oxidation, or sol-gel deposition.

[0040] In one embodiment, the thickness of the P-type doped layer 3 is 2nm-10nm. It is understood that the thickness of the P-type doped layer 3 can be selected from any value between 2nm and 10nm. Specifically, the thickness of the P-type doped layer 3 includes, but is not limited to, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, and 10nm.

[0041] In this invention, the P-type doped layer 3 is deposited using techniques such as chemical vapor deposition (CVD), sputtering, physical vapor deposition (PVD), or reactive physical vapor deposition (RPD).

[0042] In this invention, the second passivation layer 5 is a silicon dioxide layer or a hydrogenated intrinsic amorphous silicon layer, preferably a silicon dioxide layer. Further, the thickness of the second passivation layer 5 is 1 nm-8 nm, preferably 1 nm-4 nm. This configuration helps to further reduce dark degradation caused by ultraviolet light and further improve the conversion efficiency of the solar cell. In this invention, the N-type doped layer 6 can be an N-type doped microcrystalline silicon layer, an N-type doped amorphous silicon layer, or an N-type doped zinc oxide layer, preferably an N-type doped zinc oxide layer. Further, the thickness of the N-type doped layer 6 is 8 nm-22 nm, preferably 14 nm-20 nm. This configuration utilizes the high electron mobility, wide bandgap (3.0 eV-3.5 eV), and good optical transparency of zinc oxide, allowing it to function as an electron transport layer when used as the N-type doped layer 6. This promotes efficient charge transport and reduces recombination losses, enabling photons to effectively reach the active layer and further improving the conversion efficiency of the solar cell.

[0043] In one embodiment, the first surface is textured, and the second surface is either polished or textured, preferably the first surface is textured and the second surface is polished. This configuration allows the textured first surface to effectively enhance light trapping and absorption in the solar cell, while the polished second surface can reflect longer wavelength photons back into the solar cell, helping to absorb more light into the cell and thus improving the cell's photoelectric conversion efficiency.

[0044] It should be noted that, in this invention, the method for preparing the first surface as a textured surface is as follows: texturing is performed in a dilute alkaline solution using an anisotropic wet etching method. Then, the silicon substrate 1 is cleaned using the RCA standard cleaning method, specifically by sequentially cleaning the silicon substrate 1 with deionized water, RCA1, deionized water, and RCA2 and deionized water.

[0045] During texturing, it is crucial to protect the surfaces of the silicon substrate 1 that do not require texturing from the etching solution to prevent unnecessary damage to the polished surfaces. Single-sided texturing is typically performed using a mask or protective layer that covers one side of the silicon substrate 1 during etching. The mask or protective layer can be made of various materials, such as photoresist, paraffin wax, or polymers. Besides using a mask or protective layer to shield the surfaces that do not require texturing, another method is single-sided etching, where the surface of the silicon substrate 1 requiring texturing is immersed in the etching solution, while the surface not requiring texturing is covered with a water film. The etching solution is very shallow, so it does not affect the water film coverage on the surface not requiring texturing, but it still provides excellent etching results for the surface requiring texturing.

[0046] In one embodiment, the thickness of the first transparent conductive oxide layer 4 is 60nm-80nm; it is understood that the thickness of the first transparent conductive oxide layer 4 can be selected from any value between 60nm and 80nm. Specifically, the thickness of the first transparent conductive oxide layer 4 includes, but is not limited to, 60nm, 65nm, 70nm, 75nm, and 80nm. This configuration, by adjusting the thickness of the first transparent conductive oxide layer 4, allows light to reach the active layer while providing a low-resistance path for current flow; moreover, it reduces surface reflection, enhances light absorption, and facilitates contact with the nickel oxide layer, helping to further effectively extract the photogenerated current, ensuring optimal electron transport, and further improving the overall performance of the battery.

[0047] In one embodiment, the thickness of the second transparent conductive oxide layer 7 is 50nm-70nm. It is understood that the thickness of the second transparent conductive oxide layer 7 can be selected from any value between 50nm and 70nm; specifically, the thickness of the second transparent conductive oxide layer 7 includes, but is not limited to, 50nm, 55nm, 60nm, 65nm, and 70nm. This configuration is beneficial for further improving the overall performance of the battery.

[0048] It is understood that in this invention, the first transparent conductive oxide layer 4 and the second transparent conductive oxide layer 7 serve as conductive electrodes, which not only help reduce the reflection of light on the battery surface, but also allow light to pass through while enabling the rapid extraction of charge carriers.

[0049] Specifically, in one embodiment, the materials of the first transparent conductive oxide layer 4 and the second transparent conductive oxide layer 7 are each independently including, but not limited to, one or more of indium tin oxide, tungsten-doped indium oxide, cerium-doped indium oxide, aluminum-doped zinc oxide, indium-doped cadmium oxide, and antimony-doped tin oxide.

[0050] In this invention, the first transparent conductive oxide layer 4 and the second transparent conductive oxide layer 7 are each independently selected from, but not limited to, magnetron sputtering (PVD), evaporation, or chemical vapor deposition (CVD).

[0051] In one embodiment, the first surface is the light-receiving surface, and the second surface is the backlighting surface; it can be understood that, compared to traditional solar cell structures, this solar cell structure is an inverted structure, such as... Figure 1 As shown in the diagram. This configuration fully utilizes the relatively wide bandgap of the nickel oxide layer, allowing the solar cell to absorb more photons and thus improve its photoelectric conversion efficiency.

[0052] Combination Figure 1As shown, in this invention, a first metal electrode 8 is provided on the surface of the first transparent conductive oxide layer 4 away from the nickel oxide layer, and a second metal electrode 9 is provided on the surface of the second transparent conductive oxide layer 7 away from the N-type doped layer 6.

[0053] Furthermore, the first metal electrode 8 is preferably a silver electrode, and the second metal electrode 9 is preferably a silver electrode.

[0054] The following provides specific embodiments and comparative examples to further illustrate the solar cell of this utility model in detail. Unless otherwise specified, all raw materials used in the following specific embodiments are commercially available.

[0055] Example 1

[0056] The solar cell structure includes a silicon substrate (commercially available N-type c-silicon wafer grown by Zokrasky). The first surface of the silicon substrate is textured, and the second surface is polished. The first surface is sequentially stacked with a silicon dioxide layer with a thickness of 2 nm, a nickel oxide layer with a thickness of 5 nm, and a first indium tin oxide layer with a thickness of 70 nm. A first silver electrode is disposed on the first indium tin oxide layer. The second surface is sequentially stacked with an intrinsic amorphous silicon layer with a thickness of 2 nm, an N-type doped amorphous silicon layer with a thickness of 5 nm, and a second indium tin oxide layer with a thickness of 70 nm. A second silver electrode is disposed on the second indium tin oxide layer.

[0057] Comparative Example 1

[0058] The solar cell structure includes a silicon substrate (commercially available N-type c-silicon wafer grown by Zokrasky). The first surface of the silicon substrate is textured, and the second surface is polished. The first surface is sequentially stacked with an intrinsic amorphous silicon layer with a thickness of 2 nm, a nickel oxide layer with a thickness of 5 nm, and a first indium tin oxide layer with a thickness of 70 nm. A first silver electrode is disposed on the first indium tin oxide layer. The second surface is sequentially stacked with an intrinsic amorphous silicon layer with a thickness of 2 nm, an N-type doped amorphous silicon layer with a thickness of 5 nm, and a second indium tin oxide layer with a thickness of 70 nm. A second silver electrode is disposed on the second indium tin oxide layer.

[0059] Comparative Example 2

[0060] The solar cell structure includes a silicon substrate (commercially available N-type c-silicon wafer grown by Zokrasky). The first surface of the silicon substrate is textured, and the second surface is polished. The first surface is sequentially stacked with an intrinsic amorphous silicon layer with a thickness of 2 nm, an N-type doped amorphous silicon layer with a thickness of 5 nm, and a first indium tin oxide layer with a thickness of 70 nm. A first silver electrode is disposed on the first indium tin oxide layer. The second surface is sequentially stacked with an intrinsic amorphous silicon layer with a thickness of 2 nm, a P-type doped amorphous silicon layer with a thickness of 5 nm, and a second indium tin oxide layer with a thickness of 70 nm. A second silver electrode is disposed on the second indium tin oxide layer.

[0061] The solar cells provided in Example 1 and Comparative Examples 1-2 were tested, and the test results are as follows: Figures 2-3 As shown, from Figures 2-3 As can be seen, compared to Comparative Examples 1-2, the solar cell provided in Example 1 has higher external quantum efficiency (EQE) and absorption in the short wavelength range, and lower transmittance in the long wavelength (near-infrared region). Furthermore, the short-circuit current density (Jsc) of Example 1 was measured to exceed 40 mA / cm². 2 The solar cell in Example 1 has a high short-circuit current density, indicating that there is less recombination of electrons and holes and that the solar cell has good charge separation efficiency.

[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 implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A solar cell, characterized by, The solar cell comprises: a silicon substrate having opposite first and second surfaces; a first passivation layer, a P-doped layer and a first transparent conductive oxide layer are sequentially stacked on the first surface, wherein the first passivation layer is a silicon dioxide layer, and the P-doped layer is a nickel oxide layer; a second passivation layer, an N-doped layer and a second transparent conductive oxide layer are sequentially stacked on the second surface.

2. The solar cell according to claim 1, characterized in that, The thickness of the first passivation layer is 1-5 nm. And / or, the thickness of the P-doped layer is 2-10 nm.

3. The solar cell according to claim 1, characterized in that, The N-doped layer is an N-doped zinc oxide layer.

4. The solar cell according to claim 3, characterized in that, The thickness of the N-doped layer is 8-22 nm.

5. The solar cell of claim 1, wherein The second passivation layer is a silicon dioxide layer.

6. The solar cell according to claim 5, characterized in that, The thickness of the second passivation layer is 1-8 nm.

7. The solar cell of claim 1, wherein The first surface is a textured surface, and the second surface is a polished surface or a textured surface.

8. The solar cell of claim 1, wherein, The thickness of the first transparent conductive oxide layer is 60-80 nm. And / or, the thickness of the second transparent conductive oxide layer is 50-70 nm.

9. The solar cell according to any one of claims 1 to 8, characterized in that, The first surface is a light-receiving surface, and the second surface is a back surface.

10. A photovoltaic module, characterized by, The solar cell comprises any one of claims 1-9.

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