Solar cell and photovoltaic module

Abstract

The utility model discloses a solar cell and a photovoltaic module, the solar cell comprises electrodes, a substrate layer, an oxide layer and a first oxide layer, the electrodes comprise a first electrode and a second electrode, the substrate layer is provided with a first surface and a second surface which are oppositely arranged along the thickness direction of the solar cell, the oxide layer is arranged on the first surface, and the first oxide layer is arranged on the second surface. The first oxide layer is arranged on the second face and provided with holes, and projections of the first electrode and the oxide layer and projections of the second electrode and the first oxide layer are at least partially overlapped in the thickness direction of the solar cell. According to the solar cell, metal contact recombination and parasitic absorption of the light receiving surface (namely the first surface) can be reduced through the oxide layer, improvement of photoelectric conversion efficiency and short-circuit current is facilitated, the transmission process of part of electrons has directivity through the first oxide layer, improvement of the transmission efficiency of the electrons is facilitated, and the transmission efficiency of the electrons is improved. Therefore, the working performance of the solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic modules, and in particular to a solar cell and a photovoltaic module. Background Art

[0002] Existing tunnel oxide passivated contact (TOPCon) solar cells are usually composed of a grid line, a passivation layer, a substrate, a tunnel oxide layer and a polycrystalline silicon layer (Polycrystalline Silicon, Poly-Si). Among them, the TOPCon cell can reduce the possibility of metal recombination through the Poly-Si structure, but because the Poly-Si structure exists on both sides of the TOPCon cell structure, when the TOPCon cell is irradiated by sunlight, the loss caused by parasitic absorption is large, which affects the short-circuit current of the TOPCon cell, and further leads to a low photoelectric conversion efficiency of the TOPCon cell. Utility Model Content

[0003] In view of this, the present application provides a solar cell, namely a photovoltaic module, to solve the technical problems in the prior art of large losses caused by parasitic absorption and low photoelectric conversion efficiency.

[0004] In a first aspect, the present application provides a solar cell, the solar cell comprising an electrode, a substrate layer, an oxide layer and a first oxide layer, the electrode comprising a first electrode and a second electrode; along the thickness direction of the solar cell, the substrate layer has a first surface and a second surface arranged opposite to each other; the oxide layer is arranged on the first surface and is electrically connected to the first electrode; the first oxide layer is arranged on the second surface, and the first oxide layer has holes; wherein the projections of the first electrode and the oxide layer along the thickness direction of the solar cell at least partially overlap, and the projections of the second electrode and the first oxide layer along the thickness direction of the solar cell at least partially overlap.

[0005] In the embodiment of the present application, along the thickness direction of the solar cell, the oxide layer is arranged on the first surface of the substrate layer, so that the first electrode and the substrate layer can be separated by the oxide layer in this direction. Due to the difference in work function between the first electrode and the oxide layer, the electrons can cause band bending in the process of flowing between the first electrode and the substrate layer, thereby causing electron accumulation at the negative electrode contact of the first electrode, and then causing asymmetric conductivity of electrons and holes in the contact area, which is beneficial to reducing the metal contact recombination between the first electrode and the substrate layer, reducing current loss, improving the working performance of the solar cell, and improving the photoelectric conversion efficiency of the solar cell. And because the oxide layer is arranged between the first electrode and the substrate layer, there is no need to arrange a polysilicon layer on the first surface of the substrate layer, thereby reducing the loss caused by parasitic absorption, improving the conversion rate of absorbed photons, and being beneficial to improving the short-circuit current and photoelectric conversion efficiency, which is more in line with actual use requirements.

[0006] In addition, along the thickness direction of the solar cell, the first oxide layer is arranged on the second surface, and holes are also arranged in the first oxide layer, so that electrons can be transmitted through the holes during the operation of the solar cell. At the same time, the projections of the second electrode and the first oxide layer along the thickness direction of the solar cell at least partially overlap, so that the holes can play a guiding role in the process of transmitting electrons, which is beneficial to improving the transmission efficiency of electrons and improving the overall working performance of the solar cell.

[0007] Therefore, the solar cell in this embodiment can reduce the metal contact recombination and parasitic absorption of the light-receiving surface (i.e., the first surface) through the oxide layer, which is beneficial to the improvement of the photoelectric conversion efficiency and the short-circuit current. At the same time, the transmission process of some electrons can be directed through the first oxide layer, which is beneficial to improve the transmission efficiency of electrons, thereby improving the working performance of the solar cell.

[0008] In a possible embodiment, the solar cell also includes a passivation layer, and the passivation layer includes a first passivation layer and a second passivation layer; the first passivation layer is arranged on the first surface, and along the thickness direction of the solar cell, the first passivation layer at least partially covers the oxide layer, and the first electrode passes through the first passivation layer and is electrically connected to the oxide layer.

[0009] In a possible implementation, along the thickness direction of the solar cell, surfaces of the first passivation layer and the oxide layer are both pyramid velvet structures.

[0010] In a possible implementation manner, the oxide layer is formed of TiOx, or TiONx, or SrOx.

[0011] In a possible implementation manner, the width dimension of the oxide layer is a1, the width dimension of the first electrode is a2, and a1 and a2 satisfy: a1>a2.

[0012] In a possible implementation, along a plane perpendicular to the thickness direction of the solar cell, the area of ​​the oxide layer is S1, the area of ​​the first surface is S2, and S1 and S2 satisfy: 0.01≤S1 / S2≤0.15.

[0013] In a possible implementation, the solar cell further includes an oxide layer, a polysilicon layer and a second passivation layer, and the oxide layer, the polysilicon layer and the second passivation layer are stacked in sequence along the direction of the second surface away from the first surface; and along the thickness direction of the solar cell, the second electrode penetrates the second passivation layer and is electrically connected to the polysilicon layer.

[0014] In a possible implementation, the oxide layer includes the first oxide layer and the second oxide layer, and along a plane perpendicular to a thickness direction of the solar cell, the first oxide layer and the second oxide layer are adjacently arranged, and the first oxide layer and the second oxide layer are both provided with the hole;

[0015] The density of the holes in the first oxide layer is ρ1, the density of the holes in the second oxide layer is ρ2, and ρ1 and ρ2 satisfy: 10 2 ≤ρ1 / ρ2≤10 6 .

[0016] In a possible implementation manner, the density of the holes in the first oxide layer is ρ1, and ρ1 satisfies 10 5 cm -2 ≤ρ1≤10 8 cm -2 , the density of the holes in the second oxide layer is ρ2, and ρ2 satisfies 10 2 cm -2 ≤ρ2≤10 3 cm -2 .

[0017] A second aspect of the present application provides a photovoltaic module, which includes a first cover plate, a second cover plate, a first adhesive film, a second adhesive film and a battery string that are stacked. The battery string is formed by electrically connecting a plurality of solar cells. The solar cells are the solar cells described above. Along the thickness direction of the solar cells, the first cover plate is located on the side of the battery string facing the sunlight, the second cover plate is located on the side of the battery string away from the sunlight, the first adhesive film is located between the first cover plate and the battery string, and the second adhesive film is located between the second cover plate and the battery string.

[0018] In the embodiment of the present application, a battery string is formed by electrically connecting a plurality of the solar cells described above, and two adjacent solar cells are electrically connected by welding strips. The first cover plate and the second cover plate can be used to protect the internal packaging material (i.e., the first adhesive film and the second adhesive film) and the battery string from mechanical damage and external environmental erosion. The two also have good insulation properties, low water vapor permeability, good electrical insulation and a certain bonding strength, which are beneficial to improving the service life of the photovoltaic module. The first adhesive film and the second adhesive film can be used to encapsulate and protect the battery string to prevent the external environment from affecting the performance of the battery string, and the first adhesive film and the second adhesive film can bond the first cover plate, the battery string and the second cover plate together, and have a certain bonding strength, and also have high light transmittance, high volume resistivity, good UV aging resistance and moisture and heat aging resistance, can provide long-term strong bonding, which is beneficial to improving the structural stability and structural strength of the photovoltaic module.

[0019] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 A cross-sectional view of a solar cell provided in this application;

[0022] Figure 2 for Figure 1 Top view of the middle oxide layer;

[0023] Figure 3 This is a cross-sectional view of the photovoltaic module provided in this application.

[0024] Description of reference numerals:

[0025] 1- Solar cell;

[0026] 11-electrode;

[0027] 111- a first electrode;

[0028] 112- a second electrode;

[0029] 12-basal layer;

[0030] 121- first page;

[0031] 122-side 2;

[0032] 13- oxide layer;

[0033] 14- oxide layer;

[0034] 141- first oxide layer;

[0035] 142- second oxide layer;

[0036] 143-hole;

[0037] 15-polysilicon layer;

[0038] 16- passivation layer;

[0039] 161- first passivation layer;

[0040] 162- second passivation layer;

[0041] 2- Photovoltaic modules;

[0042] 21- first cover plate;

[0043] 22- second cover plate;

[0044] 23- first adhesive film;

[0045] 24- second adhesive film;

[0046] 25-battery string.

[0047] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0048] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0049] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0050] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0051] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] The embodiment of the present application provides a solar cell, such as Figure 1 and Figure 2 As shown, the solar cell 1 includes a stacked electrode 11, a base layer 12, an oxide layer 13 and a first oxide layer 141. The electrode 11 includes a first electrode 111 and a second electrode 112. Along the thickness direction of the solar cell 1, the base layer 12 has a first surface 121 and a second surface 122 that are opposite to each other. The first electrode 111 is arranged close to the first surface 121 of the base layer 12, and the second electrode 112 is arranged close to the second surface 122 of the base layer 12. At the same time, the oxide layer 13 is arranged on the first surface 121 and is electrically connected to the first electrode 111. The first oxide layer 141 is arranged on the second surface 122, and the first oxide layer 141 also has a hole 143.

[0053] In the embodiment of the present application, along the thickness direction of the solar cell 1, the oxide layer 13 is arranged on the first surface 121 of the base layer 12, so that the first electrode 111 and the base layer 12 can be separated by the oxide layer 13 in this direction. Since there is a work function difference between the first electrode 111 and the oxide layer 13, the electrons can cause band bending in the process of flowing between the first electrode 111 and the base layer 12, thereby causing electron accumulation at the negative electrode contact of the first electrode 111, and then causing asymmetric conductivity of electrons and holes in the contact area, which is beneficial to reducing the metal contact recombination between the first electrode 111 and the base layer 12, reducing current loss, improving the working performance of the solar cell 1, and improving the photoelectric conversion efficiency of the solar cell 1. And because the oxide layer 13 is arranged between the first electrode 111 and the base layer 12, there is no need to arrange the polysilicon layer 15 on the first surface 121 of the base layer 12, thereby reducing the loss caused by parasitic absorption, improving the conversion rate of absorbed photons, and being beneficial to improving the short-circuit current and photoelectric conversion efficiency, which is more in line with actual use requirements.

[0054] In addition, along the thickness direction of the solar cell 1, the first oxide layer 141 is arranged on the second surface 122, and a hole 143 is also arranged in the first oxide layer 141, so that electrons can be transmitted through the hole 143 during the operation of the solar cell 1. At the same time, the projections of the second electrode 112 and the first oxide layer 141 along the thickness direction of the solar cell 1 at least partially overlap, so that the hole 143 can play a guiding role in the process of transmitting electrons, which is beneficial to improving the transmission efficiency of electrons and improving the overall working performance of the solar cell 1.

[0055] Therefore, the solar cell 1 in this embodiment can reduce the metal contact recombination and parasitic absorption of the light-receiving surface (i.e., the first surface 121) through the oxide layer 13, which is beneficial to the improvement of the photoelectric conversion efficiency and the short-circuit current. At the same time, the transmission process of some electrons can be directed through the first oxide layer 141, which is beneficial to improve the transmission efficiency of electrons, thereby improving the working performance of the solar cell 1.

[0056] In a possible implementation, the first electrode 111 and the second electrode 112 may be formed by screen printing or electroplating. Specifically, the first electrode 111 and the second electrode 112 may be made of one or more of silver, aluminum, nickel and copper.

[0057] In a specific embodiment, Figure 1 As shown, the solar cell 1 also includes a passivation layer 16, and the passivation layer 16 includes a first passivation layer 161. The first passivation layer 161 is arranged on the first surface 121, and along the thickness direction of the solar cell 1, at least a portion of the first passivation layer 161 covers the oxide layer 13, and the first electrode 111 passes through the first passivation layer 161 and is electrically connected to the oxide layer 13.

[0058] In the embodiment of the present application, along the thickness direction of the solar cell 1, the oxide layer 13 covers the position on the first surface 121 opposite to the first electrode 111, and the first passivation layer 161 covers the first surface 121 and the oxide layer 13. The first passivation layer 161 and the oxide layer 13 can achieve multi-layer passivation to reduce the probability of electron recombination, thereby reducing the loss of electrons during transmission, improving the transmission efficiency of electrons, and then increasing the open circuit voltage of the solar cell 1, improving the working efficiency of the solar cell 1, and at the same time, it can also reduce the possibility of oxidation of the surface of the solar cell 1 and increase the working life of the solar cell 1.

[0059] Specifically, the first passivation layer 161 can be one or more stacks of silicon nitride, silicon oxide, silicon oxynitride, titanium oxide, and aluminum oxide films, and along the thickness direction of the solar cell 1, the thickness dimension of the first passivation layer 161 can be h1, and h1 satisfies 50nm≤h1≤150nm, wherein h1 can specifically be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, etc.

[0060] When the thickness of the first passivation layer 161 is too small (for example, h1 is less than 50 nm), the thickness of the first passivation layer 161 is too thin, so that the strength of the first passivation layer 161 is low, and the first passivation layer 161 is easily damaged.

[0061] When the thickness of the first passivation layer 161 is too large (for example, h1 is greater than 150 nm), the thickness of the first passivation layer 161 is too thick, so that the photoelectric conversion efficiency of the solar cell 1 is low and the production cost is high.

[0062] Therefore, when the thickness of the first passivation layer 161 satisfies 50nm≤h1≤150nm, the thickness of the first passivation layer 161 is moderate, so that the first passivation layer 161 has a higher strength, and at the same time can facilitate the transmission of electrons, improve the photoelectric conversion efficiency of the solar cell 1, and is also beneficial to saving materials and reducing the production cost of the first passivation layer 161.

[0063] In a specific embodiment, Figure 1 As shown, along the thickness direction of the solar cell 1 , the surfaces of the first passivation layer 161 and the oxide layer 13 are both pyramid velvet structures.

[0064] In the embodiment of the present application, during the production process of the solar cell 1, the first surface 121 of the base layer 12 is textured so that a partial area of ​​the first surface 121 forms a pyramid velvet structure along the thickness direction of the solar cell 1, so that when the oxide layer 13 and the first passivation layer 161 are subsequently prepared on the first surface 121, the parts of the two covering the area can also form a pyramid shape. Therefore, when the light-receiving surface (i.e., the first surface 121) of the solar cell 1 is illuminated, the pyramid velvet structure of the first surface 121 can reduce the reflectivity of the incident light, thereby reducing the reflection loss, which is beneficial to improving the absorption rate of the solar cell 1 to light, thereby improving the photoelectric conversion efficiency of the solar cell 1. Specifically, the base size of the pyramid velvet structure can be 1μm-10μm, so that the reflectivity of the pyramid velvet structure can reach 3%-14%, which is beneficial to reducing optical losses.

[0065] In a specific embodiment, the oxide layer 13 may be formed of TiOx, or TiONx, or SrOx.

[0066] In the embodiment of the present application, when the material of the oxide layer 13 is TiOx, or TiONx, or SrOx, due to the difference in work function between the electrode 11 and the oxide layer 13, the electrons can cause band bending during the flow between the first electrode 111 and the substrate layer 12, thereby causing electron accumulation at the negative electrode contact of the first electrode 111, and then causing asymmetric conductivity of electrons and holes in the contact area, which is beneficial to further reduce the metal contact recombination between the first electrode 111 and the substrate layer 12, reduce current loss, and improve the working performance of the solar cell 1. Wherein TiOx, TiONx and SrOx represent titanium oxide, titanium oxynitride and strontium oxide respectively, for example, titanium oxide can be titanium dioxide, titanium oxynitride can be titanium oxynitride, and strontium oxide can be strontium oxide or bismuth vanadate.

[0067] In a specific embodiment, Figure 1 As shown, the width dimension of the oxide layer 13 may be a1, the width dimension of the first electrode 111 may be a2, and a1 and a2 satisfy: a1>a2.

[0068] In the embodiment of the present application, when the width dimension of the oxide layer 13 is greater than the width dimension of the first electrode 111, the oxide layer 13 can separate the first electrode 111 from the base layer 12 in the thickness direction of the solar cell 1, so that the difference in work function between the first electrode 111 and the oxide layer 13 can cause band bending in the process of electrons flowing between the first electrode 111 and the base layer 12, thereby causing electron accumulation at the negative electrode contact of the first electrode 111, and then causing asymmetric conductivity of electrons and holes in the contact area, which is beneficial to reduce the metal contact recombination between the first electrode 111 and the base layer 12, reduce current loss, improve the working performance of the solar cell 1, and improve the photoelectric conversion efficiency of the solar cell 1. At the same time, it can also improve the supporting effect of the oxide layer 13 on the first electrode 111, thereby improving the stability of the connection between the two, so that the electrical connection between the oxide layer 13 and the first electrode 111 is more reliable, which is convenient for the transmission of electrons, thereby ensuring the stability and reliability of the solar cell 1 during operation.

[0069] Specifically, the width dimension a1 of the oxide layer 13 satisfies 20 μm≤a1≤200 μm, wherein a1 can specifically be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc.

[0070] When the width dimension a1 of the oxide layer 13 satisfies 20μm≤a1≤200μm, the solar cell 1 generates less parasitic absorption, which is beneficial to reduce the optical loss of the light-receiving surface (i.e., the first surface 121), improve the passivation effect and optical utilization, and thus improve the conversion efficiency of the solar cell 1.

[0071] More specifically, the thickness dimension of the oxide layer 13 can be h2, and h2 satisfies 20nm≤h2≤300nm, where h2 can specifically be 20nm, 40nm, 60nm, 80nm, 100nm, 120nm, 140nm, 160nm, 180nm, 200nm, 220nm, 240nm, 260nm, 280nm, 300nm, etc.

[0072] When the thickness of the oxide layer 13 is too small (for example, h2 is less than 20 nm) or too large (for example, h2 is greater than 300 nm), the contact effect between the oxide layer 13 and the first electrode 111 is reduced, and the stability of the electrical connection is reduced.

[0073] Therefore, when the thickness dimension h2 of the oxide layer 13 satisfies 20nm≤h2≤300nm, the thickness of the oxide layer 13 is moderate, which is beneficial to improve the contact effect between the oxide layer 13 and the first electrode 111, improve the electron transmission efficiency, and thus improve the photoelectric conversion efficiency of the solar cell 1.

[0074] In a specific embodiment, Figure 1 As shown, along a plane perpendicular to the thickness direction of the solar cell 1 , the area of ​​the oxide layer 13 may be S1 , the area of ​​the first surface 121 may be S2 , and S1 and S2 satisfy: 0.01≤S1 / S2≤0.15.

[0075] In the embodiments of the present application, S1 / S2 can specifically be 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, etc.

[0076] When the ratio of the area of ​​the oxide layer 13 to the area of ​​the first surface 121 is too small (for example, S1 / S2 is less than 0.01), the area of ​​the oxide layer 13 is too small, so that the contact effect between the oxide layer 13 and the first electrode 111 is reduced, and the stability of the electrical connection is reduced.

[0077] When the ratio of the area of ​​the oxide layer 13 to the area of ​​the first surface 121 is too large (for example, S1 / S2 is greater than 0.15), the area of ​​the oxide layer 13 is too large, so that the production cost of the oxide layer 13 is high.

[0078] Therefore, when the ratio of the area of ​​the oxide layer 13 to the area of ​​the first surface 121 satisfies 0.01≤S1 / S2≤0.15, the area of ​​the oxide layer 13 is moderate, which can improve the direct contact effect between the oxide layer 13 and the first electrode 111 while reducing production costs, improve the electron transmission efficiency, and thus improve the photoelectric conversion efficiency of the solar cell 1.

[0079] In a specific embodiment, Figure 1 and Figure 2 As shown, the solar cell 1 also includes an oxide layer 14, a polysilicon layer 15 and a second passivation layer 162. Along the direction of the second surface 122 away from the first surface 121, the oxide layer 14, the polysilicon layer 15 and the second passivation layer 162 are stacked in sequence, and along the thickness direction of the solar cell 1, the second electrode 112 penetrates the second passivation layer 162 and is electrically connected to the polysilicon layer 15.

[0080] In the embodiment of the present application, the oxide layer 14 and the polysilicon layer 15 together form a passivation contact structure to reduce the surface recombination and metal contact recombination of the backlight surface (ie, the second surface 122 ) of the solar cell 1 , thereby increasing the open circuit voltage of the solar cell 1 .

[0081] Specifically, the oxide layer 14 may be a silicon oxide layer, and the thickness dimension of the oxide layer 14 may be h3, and h3 satisfies 0.5nm≤h3≤5nm, wherein h3 may specifically be 0.5nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm, 5nm, etc.

[0082] When the thickness of the oxide layer 14 is too small (for example, h3 is less than 0.5 nm), the thickness of the oxide layer 14 is too thin, which may easily lead to an increase in the interface state density and a decrease in the passivation effect.

[0083] When the thickness of the oxide layer 14 is too large (for example, h3 is greater than 5 nm), the oxide layer 14 is too thick, which may easily lead to a poor tunneling effect.

[0084] Therefore, when the thickness of the oxide layer 14 satisfies 0.5nm≤h3≤5nm, the thickness of the oxide layer 14 is moderate, so that electrons tunnel into the polysilicon layer 15 while reducing the possibility of hole recombination, thereby reducing recombination losses and improving the photoelectric conversion efficiency of the solar cell 1.

[0085] Along the thickness direction of the solar cell 1 , the second electrode 112 penetrates the second passivation layer 162 and is electrically connected to the polysilicon layer 15 . The second electrode 112 and the polysilicon layer 15 form a good ohmic contact, which is beneficial to the transmission of electrons.

[0086] The polysilicon layer 15 may be doped with boron to form a doped polysilicon layer, wherein the activation probability of the boron element is 30%-80%, and the concentration of the activated boron element is 4×10 18 -9×10 20 atom / cm 3 , which is beneficial to improving the contact resistivity and the composite current density, and improving the photoelectric conversion efficiency of the solar cell 1.

[0087] Specifically, the thickness dimension of the polysilicon layer 15 can be h4, and h4 satisfies 50nm≤h4≤500nm, wherein h4 can specifically be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc.

[0088] When the thickness of the polysilicon layer 15 is too small (for example, h4 is less than 50 nm), the thickness of the polysilicon layer 15 is too thin, resulting in excessive metallization damage and excessive contact resistance, which may easily cause efficiency loss.

[0089] When the thickness of the polysilicon layer 15 is too large (for example, h4 is greater than 500 nm), the thickness of the polysilicon layer 15 is too thick, so that the diffusion distance of electrons is relatively large, which is not conducive to the transmission of electrons.

[0090] Therefore, when the thickness of the polysilicon layer 15 satisfies 50nm≤h4≤500nm, the thickness of the polysilicon layer 15 is moderate, which is beneficial to reduce metallization loss, reduce contact resistance, and increase short-circuit current, thereby improving the photoelectric conversion efficiency of the solar cell.

[0091] Specifically, the second passivation layer 162 can be one or more stacks of silicon nitride, silicon oxide, silicon oxynitride, titanium oxide, and aluminum oxide films, and along the thickness direction of the solar cell 1, the thickness dimension of the second passivation layer 162 can be h5, and h1 satisfies 50nm≤h5≤150nm, wherein h5 can specifically be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, etc.

[0092] When the thickness of the second passivation layer 162 is too small (for example, h5 is less than 50 nm), the thickness of the second passivation layer 162 is too thin, so that the strength of the second passivation layer 162 is low, which may easily lead to damage of the second passivation layer 162 .

[0093] When the thickness of the second passivation layer 162 is too large (for example, h5 is greater than 150 nm), the thickness of the second passivation layer 162 is too thick, so that the photoelectric conversion efficiency of the solar cell 1 is low.

[0094] Therefore, when the thickness of the second passivation layer 162 satisfies 50nm≤h5≤150nm, the thickness of the second passivation layer 162 is moderate, so that the second passivation layer 162 has high strength and can facilitate the transmission of electrons, thereby improving the photoelectric conversion efficiency of the solar cell 1.

[0095] In one possible embodiment, the second surface 122 of the substrate layer 12 can be a polished surface or an etched surface to form different light trapping structures, reduce interface recombination, increase the reflection of incident light on the second surface 122, and increase the amount of light absorbed by the solar cell 1, so that the light has a chance to be reused, thereby improving the photoelectric conversion efficiency of the solar cell 1.

[0096] In a specific embodiment, Figure 1 and Figure 2 As shown, the oxide layer 14 includes a first oxide layer 141 and a second oxide layer 142 . The first oxide layer 141 and the second oxide layer 142 are adjacently arranged along a plane perpendicular to the thickness direction of the solar cell 1 . The first oxide layer 141 and the second oxide layer 142 are both provided with holes 143 .

[0097] In the embodiment of the present application, both the first oxide layer 141 and the second oxide layer 142 are provided with holes 143 for transmitting electrons. Specifically, along a plane perpendicular to the thickness direction of the solar cell 1, the density of the holes 143 in the first oxide layer 141 is greater than the density of the holes 143 in the second oxide layer 142, so that the high-density holes 143 can be used to improve the transmission efficiency of electrons, thereby improving the photoelectric conversion efficiency of the solar cell 1.

[0098] Specifically, the density of the holes 143 in the first oxide layer 141 may be ρ1, and the density of the holes 143 in the second oxide layer 142 may be ρ2, and ρ1 and ρ2 satisfy: 10 2 ≤ρ1 / ρ2≤10 6 , where ρ1 / ρ2 can be specifically 10 2 , 10 3 , 10 4 , 10 5 , 10 6 wait.

[0099] When the ratio of the density of the holes 143 in the first oxide layer 141 to the density of the holes 143 in the second oxide layer 142 is too small (for example, ρ1 / ρ2 is less than 10 2 ), the density difference between the two is too small, so that the electrons move slowly from the second oxide layer 142 to the first oxide layer 141, which easily leads to low electron transmission efficiency.

[0100] When the ratio of the density of the holes 143 in the first oxide layer 141 to the density of the holes 143 in the second oxide layer 142 is too large (for example, ρ1 / ρ2 is greater than 10 6 ), the density difference between the two is too large, resulting in uneven distribution of the holes 143 in the oxide layer 14, which can easily lead to a decrease in the overall passivation quality of the oxide layer 14.

[0101] Therefore, when the ratio of the density of the holes 143 in the first oxide layer 141 to the density of the holes 143 in the second oxide layer 142 satisfies 10 2 ≤ρ1 / ρ2≤10 6 When the density difference between the two is moderate, it is beneficial to improve the electron transmission efficiency while ensuring the passivation quality of the oxide layer 14.

[0102] In a specific embodiment, the density of the holes 143 in the first oxide layer 141 is ρ1, and ρ1 satisfies 10 5 cm -2 ≤ρ1≤10 8 cm -2 , where ρ1 can be specifically 10 5 cm -2 , 10 6 cm -2 , 10 7 cm -2 , 10 8 cm -2 wait.

[0103] When the density of the holes 143 in the first oxide layer 141 is too small (for example, ρ1 is less than 10 5 cm -2 ), the number of holes 143 in the first oxide layer 141 is too small, resulting in a low electron transmission efficiency.

[0104] When the density of the holes 143 in the first oxide layer 141 is too large (for example, ρ1 is greater than 10 8 cm -2 ), the number of holes 143 in the first oxide layer 141 is too large, so that the defects on the first oxide layer 141 are too dense and concentrated, which easily leads to a decrease in the overall passivation quality of the first oxide layer 141.

[0105] Therefore, when the density of the holes 143 in the first oxide layer 141 satisfies 10 5 cm -2 ≤ρ1≤10 8 cm -2 When the number of holes 143 in the first oxide layer 141 is moderate, it is beneficial to improve the overall passivation quality of the first oxide layer 141 while improving the electron transmission efficiency.

[0106] In addition, the density of the holes 143 in the second oxide layer 142 is ρ2, and ρ2 satisfies 10 2 cm -2 ≤ρ2≤10 3 cm -2 , so as to ensure the transmission efficiency of electrons in the second oxide layer 142 and the passivation quality of the second oxide layer 142, thereby helping to improve the overall working performance of the oxide layer 14.

[0107] The present application also provides a photovoltaic module, such as Figure 1 , Figure 2 and Figure 3 As shown, along the thickness direction of the photovoltaic module 2, the photovoltaic module 2 includes a first cover plate 21, a first adhesive film 23, a battery string 25, a second adhesive film 24, and a second cover plate 22 that are stacked. Along the thickness direction of the solar cell 1, the first cover plate 21 is located on the side of the battery string 25 facing the sunlight, the second cover plate 22 is located on the side of the battery string 25 away from the sunlight, the first adhesive film 23 is located between the first cover plate 21 and the battery string 25, and the second adhesive film 24 is located between the second cover plate 22 and the battery string 25.

[0108] In the embodiment of the present application, the battery string 25 is formed by electrically connecting a plurality of the above-mentioned solar cells 1, and two adjacent solar cells 1 are electrically connected via a welding ribbon.

[0109] The first cover plate 21 and the second cover plate 22 can be used to protect the internal packaging materials (i.e., the first adhesive film 23 and the second adhesive film 24) and the battery string 25 from mechanical damage and external environmental corrosion. Both also have good insulation properties, low water vapor permeability, good electrical insulation and a certain bonding strength, which is beneficial to improve the service life of the photovoltaic module 2.

[0110] The first adhesive film 23 and the second adhesive film 24 can be used to encapsulate and protect the battery string 25 to prevent the external environment from affecting the performance of the battery string 25, and the first adhesive film 23 and the second adhesive film 24 can bond the first cover plate 21, the battery string 25 and the second cover plate 22 together, and have a certain bonding strength, and also have a high light transmittance, a high volume resistivity, good UV aging resistance and moisture and heat aging resistance, can provide a long-term strong bonding effect, which is beneficial to improve the structural stability and structural strength of the photovoltaic module 2.

[0111] In summary, the solar cell 1 provided in the present application fills the first surface 121 of the substrate layer 12 with the oxide layer 13 and the first passivation layer 161, and separates the first electrode 111 from the substrate layer 12, so that the difference in work function between the first electrode 111 and the oxide layer 13 can cause energy band bending in the process of electrons flowing between the first electrode 111 and the substrate layer 12, thereby causing electron accumulation at the negative electrode contact of the first electrode 111, and further causing asymmetric conductivity of electrons and holes in the contact area, which is beneficial to reducing the metal contact recombination between the first electrode 111 and the substrate layer 12, reducing current loss, and improving solar cell performance. The working performance of the solar cell 1 is improved, and the photoelectric conversion efficiency of the solar cell 1 is improved. At the same time, by setting the oxide layer 13 between the first electrode 111 and the substrate layer 12, the first surface 121 of the substrate layer 12 does not need to be provided with a polysilicon layer 15, which can reduce the loss caused by parasitic absorption, improve the absorption effect of the substrate layer 12 on light, and optimize the working performance of the solar cell 1. Secondly, through the first oxide layer 141 and the holes 143 in the first oxide layer 141, the transmission efficiency of electrons can be improved, which is beneficial to further improve the photoelectric conversion efficiency of the solar cell 1, and then improve the working performance of the photovoltaic module 2 composed of the solar cell 1.

[0112] The above describes in detail the structure, features and effects of the present application based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present application, but the present application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of the present application, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present application.

Claims

1. A solar cell, characterized in that: The solar cell (1) comprises: An electrode (11), wherein the electrode (11) comprises a first electrode (111) and a second electrode (112); A base layer (12), wherein along the thickness direction of the solar cell (1), the base layer (12) has a first surface (121) and a second surface (122) that are arranged opposite to each other; an oxide layer (13), the oxide layer (13) being disposed on the first surface (121) and electrically connected to the first electrode (111); A first oxide layer (141), the first oxide layer (141) being disposed on the second surface (122), the first oxide layer (141) having a hole (143); The projections of the first electrode (111) and the oxide layer (13) along the thickness direction of the solar cell (1) at least partially overlap, and the projections of the second electrode (112) and the first oxide layer (141) along the thickness direction of the solar cell (1) at least partially overlap.

2. The solar cell according to claim 1, characterized in that The solar cell (1) further comprises a passivation layer (16), wherein the passivation layer (16) comprises a first passivation layer (161) and a second passivation layer (162); The first passivation layer (161) is arranged on the first surface (121), and along the thickness direction of the solar cell (1), at least part of the first passivation layer (161) covers the oxide layer (13), and the first electrode (111) penetrates the first passivation layer (161) and is electrically connected to the oxide layer (13).

3. The solar cell according to claim 2, characterized in that: Along the thickness direction of the solar cell (1), the surfaces of the first passivation layer (161) and the oxide layer (13) are both pyramid velvet structures.

4. The solar cell according to claim 1, characterized in that The oxide layer (13) is formed of TiOx, or TiONx, or SrOx.

5. The solar cell according to any one of claims 1 to 4, characterized in that: The width dimension of the oxide layer (13) is a1, the width dimension of the first electrode (111) is a2, and a1 and a2 satisfy: a1>a2.

6. The solar cell according to claim 5, characterized in that Along a plane perpendicular to the thickness direction of the solar cell (1), the area of ​​the oxide layer (13) is S1, the area of ​​the first surface (121) is S2, and S1 and S2 satisfy: 0.01≤S1 / S2≤0.

15.

7. The solar cell according to any one of claims 1 to 4, characterized in that: The solar cell (1) further comprises an oxide layer (14), a polycrystalline silicon layer (15) and a second passivation layer (162), wherein the oxide layer (14), the polycrystalline silicon layer (15) and the second passivation layer (162) are sequentially stacked along a direction of the second surface (122) away from the first surface (121); Furthermore, along the thickness direction of the solar cell (1), the second electrode (112) penetrates the second passivation layer (162) and is electrically connected to the polysilicon layer (15).

8. The solar cell according to claim 7, characterized in that: The oxide layer (14) comprises the first oxide layer (141) and the second oxide layer (142); along a plane perpendicular to the thickness direction of the solar cell (1), the first oxide layer (141) and the second oxide layer (142) are arranged adjacent to each other; and the first oxide layer (141) and the second oxide layer (142) are both provided with the hole (143); The density of the holes (143) in the first oxide layer (141) is ρ1, the density of the holes (143) in the second oxide layer (142) is ρ2, and ρ1 and ρ2 satisfy: 10 2 ≤ρ1 / ρ2≤10 6 .

9. The solar cell according to claim 8, characterized in that The density of the holes (143) in the first oxide layer (141) is ρ1, and ρ1 satisfies 10 5 cm -2 ≤ρ1≤10 8 cm -2 , the density of the holes (143) in the second oxide layer (142) is ρ2, and ρ2 satisfies 10 2 cm -2 ≤ρ2≤10 3 cm -2 .

10. A photovoltaic module, characterized in that: The photovoltaic module (2) comprises: A battery string (25), wherein the battery string (25) is formed by electrically connecting a plurality of solar cells (1), wherein the solar cell (1) is the solar cell (1) according to any one of claims 1 to 9; A first cover plate (21), along the thickness direction of the solar cell (1), the first cover plate (21) being located on a side of the cell string (25) facing sunlight; A first adhesive film (23), along the thickness direction of the solar cell (1), the first adhesive film (23) being located between the first cover plate (21) and the battery string (25); A second cover plate (22), along the thickness direction of the solar cell (1), the second cover plate (22) being located on a side of the cell string (25) facing away from sunlight; A second adhesive film (24), along the thickness direction of the solar cell (1), the second adhesive film (24) is located between the second cover plate (22) and the battery string (25).

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