Solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, and mainly provides a solar cell and a preparation method thereof. The solar cell comprises a silicon substrate which comprises a first surface and a second surface which are oppositely arranged; the first passivation layer, the first TCO layer and the second passivation layer are sequentially stacked on the first surface of the silicon substrate in the first direction. The solar cell provided by the invention can effectively solve the PID problem, and has a good anti-PID effect.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for preparing the same. Background Art

[0002] When photovoltaic modules in a photovoltaic power station are connected in series, they may be subjected to a huge positive or negative potential relative to the grounded frame, causing potential induced degradation (PID). The potential difference between the metal frame of the module and the cell will drive the alkali metal ions (such as sodium ions Na + ) Migrate to the surface of the cell through the packaging material, causing a large amount of charge to accumulate on the surface of the cell, which increases the carrier recombination rate and reduces the cell efficiency, causing the PID phenomenon. The PID phenomenon will reduce the cell efficiency, have a serious impact on the power generation of the photovoltaic power station, and reduce the service life and economic benefits of the photovoltaic power station.

[0003] As the mass production technology of high-efficiency crystalline silicon cells matures, the reliability requirements of downstream components are further improved. Therefore, it is necessary to provide a solar cell that is PID-resistant. Summary of the invention

[0004] The present application provides a solar cell and a method for preparing the same to solve or alleviate the above technical problems. The solar cell in the technical solution of the present application can effectively solve the potential induced degradation (PID) problem and has a good anti-PID effect.

[0005] In a first aspect, an embodiment of the present application provides a solar cell, comprising: A silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; A first passivation layer, a first TCO layer, and a second passivation layer are sequentially stacked on the first surface of the silicon substrate and along a first direction.

[0006] Optionally, the first TCO layer includes a plurality of sub-TCO layers stacked along a first direction; The refractive index of the sub-TCO layer close to the silicon substrate is greater than the refractive index of the sub-TCO layer far from the silicon substrate.

[0007] Optionally, the first TCO layer includes a first sub-TCO layer, a second sub-TCO layer, and a third sub-TCO layer stacked along a first direction; Wherein, the refractive index of the first sub-TCO layer is greater than the refractive index of the second sub-TCO layer; The refractive index of the second sub-TCO layer is greater than the refractive index of the third sub-TCO layer.

[0008] Optionally, the material of the first sub-TCO layer is aluminum-titanium co-doped zinc oxide, wherein the total mass percentage of aluminum and titanium elements is 0.1-5%; the material of the second sub-TCO layer is gallium-doped zinc oxide, wherein the mass percentage of gallium is 0.1-3%; the material of the third sub-TCO layer is aluminum-doped zinc oxide, wherein the mass percentage of aluminum element is 0.1-5%.

[0009] Optionally, the refractive index of the first sub-TCO layer is 1.9-2.2, the refractive index of the second sub-TCO layer is 1.8-2.1, and the refractive index of the third sub-TCO layer is 1.7-2.0.

[0010] Optionally, the material of the first passivation layer and the material of the second passivation layer respectively and independently include Al2O3, SiN x 、SiON x 、TiO x One or more of .

[0011] Optionally, the material of the first passivation layer includes Al2O3, SiN x 、SiON x 、TiO x One or more of; The material of the second passivation layer includes SiN x 、SiON x One or both of the following.

[0012] Optionally, the material of the first TCO layer includes one or more of fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, aluminum-gallium co-doped zinc oxide, aluminum-titanium co-doped zinc oxide, indium tin oxide, and titanium oxide.

[0013] Optionally, the mass percentage of fluorine element in the fluorine-doped tin oxide is 0.1-20%; The mass percentage of antimony element in the antimony-doped tin oxide is 0.1-20%; The mass percentage of aluminum in the aluminum-doped zinc oxide is 0.1-20%; The mass percentage of gallium in the gallium-doped zinc oxide is 0.1-20%; The mass percentage of boron in the boron-doped zinc oxide is 0.1-20%; In the aluminum-gallium co-doped zinc oxide, the total mass percentage of aluminum and gallium is 1-20%; In the aluminum-titanium co-doped zinc oxide, the total mass percentage of aluminum and titanium is 1-20%.

[0014] Optionally, the sheet resistance of the first TCO layer is 1Ω / sq-106 Ω / sq.

[0015] Optionally, the solar cell is a TOPCon solar cell; the TOPCon solar cell further includes: a first tunneling oxide layer and a first doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer.

[0016] Optionally, the solar cell is a BC solar cell; the BC solar cell also includes a first region and a second region located on a first surface of a silicon substrate, the first region and the second region are staggered and spaced from each other; the first region includes: a second tunneling oxide layer and a second doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the second region includes: a third tunneling oxide layer and a third doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along the first direction; the doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; the doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

[0017] Optionally, the solar cell further comprises: A third passivation layer, a second TCO layer, and a fourth passivation layer are sequentially stacked on the second surface of the silicon substrate and along the second direction; The second direction is opposite to the first direction.

[0018] Optionally, the solar cell is a TOPCon solar cell; The TOPCon solar cell further comprises: a diffusion doping layer between the silicon substrate and the first passivation layer; a third passivation layer and a fourth passivation layer located on the second surface of the silicon substrate and sequentially stacked along a second direction; and A first tunneling oxide layer and a first doped polysilicon layer are located between the silicon substrate and the third passivation layer and are sequentially stacked along the second direction; Wherein, the doping type of the silicon substrate is opposite to the doping type of the diffusion doping layer; The doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer.

[0019] Optionally, the solar cell is a BC solar cell; The BC solar cell further comprises: a third passivation layer and a fourth passivation layer located on the second surface of the silicon substrate and sequentially stacked along a second direction; and A first region and a second region located on the second surface of the silicon substrate, wherein the first region and the second region are staggered and spaced from each other; The first region includes: a second tunneling oxide layer and a second doped polysilicon layer located between the silicon substrate and the third passivation layer and stacked in sequence along the second direction; The second region includes: a third tunneling oxide layer and a third doped polysilicon layer located between the silicon substrate and the third passivation layer and stacked in sequence along the second direction; The doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; The doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

[0020] In a second aspect, an embodiment of the present application provides a method for preparing a solar cell provided by any of the above embodiments, comprising: Providing a silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; A first passivation layer, a first TCO layer, and a second passivation layer are sequentially stacked on the first surface of the silicon substrate and along a first direction.

[0021] The above technical solution adopted in the embodiment of the present application may have the following advantages: The solar cell of the present application forms a stacked passivation structure by sequentially stacking a first passivation layer, a first TCO (transparent conductive oxide) layer, and a second passivation layer on a silicon substrate. The TCO layer has a tight texture and can effectively block alkali metal ions from entering the interior of the silicon substrate; moreover, the TCO layer has good conductivity and, as a charge transmission channel, can quickly conduct away the charges accumulated on the surface of the battery, thereby effectively solving the potential induced decay (PID) problem and having a good anti-PID effect. In addition, the TCO layer is located between the two passivation layers, so that the TCO layer does not directly contact the silicon substrate, which can avoid the increase in the interface defect state density caused by lattice mismatch; the second passivation layer is provided, so that the TCO layer can be encapsulated and protected, and pollutants such as water vapor can be prevented from damaging the TCO layer. In short, the solar cell of the present application can effectively solve the PID problem and has a good anti-PID effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0023] Figure 1is a schematic diagram of the structure of a solar cell provided in Example 1 of the present application; Figure 2 is a schematic diagram of the structure of a solar cell provided in Example 2 of the present application; Figure 3 is a schematic diagram of the structure of a solar cell provided in Example 3 of the present application; Figure 4 is a schematic diagram of the structure of a solar cell provided in Example 4 of the present application; Figure 5 is a schematic diagram of the structure of a solar cell provided in Example 7 of the present application; Figure 6 is a schematic diagram of the structure of a solar cell provided in Example 8 of the present application; Figure 7 is a schematic diagram of the structure of a solar cell provided in Example 9 of the present application; Figure 8 It is a schematic diagram of the structure of the solar cell provided in Example 10 of the present application.

[0024] Description of reference numerals: 100. Silicon substrate; 210, first passivation layer; 220, first TCO layer; 221, first sub-TCO layer; 222, second sub-TCO layer; 223, third sub-TCO layer; 230, second passivation layer; 310, third passivation layer; 320, second TCO layer; 330, fourth passivation layer; 410, first tunneling oxide layer; 420, first doped polysilicon layer; 430, second tunneling oxide layer; 440, second doped polysilicon layer; 450, third tunneling oxide layer; 460, third doped polysilicon layer; 470, diffusion doping layer; 510, first area; 520, second area; 610, a first electrode; 620, a second electrode; D1, first direction; D2, second direction. DETAILED DESCRIPTION

[0025] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0026] like Figures 1 to 8As shown, an embodiment of the present application provides a solar cell, comprising: A silicon substrate 100, wherein the silicon substrate 100 comprises a first surface and a second surface which are arranged opposite to each other; A first passivation layer 210 , a first TCO layer 220 , and a second passivation layer 230 are sequentially stacked on the first surface of the silicon substrate 100 and along the first direction D1 .

[0027] The solar cell of the present application forms a stacked passivation structure by sequentially stacking a first passivation layer, a first TCO (transparent conductive oxide) layer, and a second passivation layer on a silicon substrate. The TCO layer has a tight texture and can effectively block alkali metal ions from entering the interior of the silicon substrate; moreover, the TCO layer has good conductivity and, as a charge transmission channel, can quickly conduct away the charges accumulated on the surface of the battery, thereby effectively solving the potential induced decay (PID) problem and having a good anti-PID effect. In addition, the TCO layer is located between the two passivation layers, so that the TCO layer does not directly contact the silicon substrate, which can avoid the increase in the interface defect state density caused by lattice mismatch; the second passivation layer is provided, so that the TCO layer can be encapsulated and protected, and pollutants such as water vapor can be prevented from damaging the TCO layer. In short, the solar cell of the present application can effectively solve the PID problem and has a good anti-PID effect.

[0028] In an optional embodiment, the first TCO layer includes a plurality of sub-TCO layers stacked along a first direction; The refractive index of the sub-TCO layer close to the silicon substrate is greater than the refractive index of the sub-TCO layer far from the silicon substrate.

[0029] When the refractive index of the sub-TCO layer close to the silicon substrate is greater than the refractive index of the sub-TCO layer far from the silicon substrate, a better anti-reflection effect can be achieved, and the absorption of incident light by the cell is increased.

[0030] In some embodiments, the first TCO layer includes a first sub-TCO layer and a second sub-TCO layer stacked along a first direction; wherein the refractive index of the first sub-TCO layer is greater than the refractive index of the second sub-TCO layer. In some embodiments, the refractive index of the first sub-TCO layer may be 1.9-2.2, and the refractive index of the second sub-TCO layer may be 1.8-2.1.

[0031] like Figure 4 and Figure 8 As shown, in an optional embodiment, the first TCO layer 220 includes a first sub-TCO layer 221, a second sub-TCO layer 222, and a third sub-TCO layer 223 stacked along a first direction D1; Wherein, the refractive index of the first sub-TCO layer is greater than the refractive index of the second sub-TCO layer; The refractive index of the second sub-TCO layer is greater than the refractive index of the third sub-TCO layer.

[0032] The stacked passivation structure composed of a plurality of sub-TCO layers whose refractive index decreases successively along the first direction can more effectively capture incident light and reduce light escape, thereby enhancing the anti-reflection effect.

[0033] In an optional embodiment, the material of the first sub-TCO layer is aluminum-titanium co-doped zinc oxide, wherein the total mass percentage of aluminum and titanium elements is 0.1-5%; the material of the second sub-TCO layer is gallium-doped zinc oxide, wherein the mass percentage of gallium is 0.1-3%; the material of the third sub-TCO layer is aluminum-doped zinc oxide, wherein the mass percentage of aluminum element is 0.1-5%.

[0034] When the material of the first sub-TCO layer is aluminum-titanium co-doped zinc oxide, the material of the second sub-TCO layer is gallium-doped zinc oxide, and the material of the third sub-TCO layer is aluminum-doped zinc oxide, and the mass percentage of each doping element is adjusted within the above range, the refractive index of the aluminum-titanium co-doped zinc oxide can be made higher than the refractive index of the gallium-doped zinc oxide, and the refractive index of the gallium-doped zinc oxide can be made higher than the refractive index of the aluminum-doped zinc oxide, thereby ensuring that the refractive indices of the first sub-TCO layer, the second sub-TCO layer, and the third sub-TCO layer decrease in sequence, which can further improve the anti-reflection effect and increase the absorption of incident light by the battery cell.

[0035] In an optional embodiment, the refractive index of the first sub-TCO layer is 1.9-2.2, the refractive index of the second sub-TCO layer is 1.8-2.1, and the refractive index of the third sub-TCO layer is 1.7-2.0. When multiple sub-TCO layers with this refractive index range constitute the first TCO layer, the first TCO layer has excellent conductivity and can match the second passivation layer to adjust the refractive index, thereby enhancing the anti-reflection effect. Specifically, the refractive index of the first sub-TCO layer can be 1.9, 2.0, 2.1 or 2.2, the refractive index of the second sub-TCO layer can be 1.8, 1.9, 2.0 or 2.1, and the refractive index of the third sub-TCO layer can be 1.7, 1.8, 1.9 or 2.0.

[0036] In an optional embodiment, the material of the first passivation layer and the material of the second passivation layer respectively and independently include Al2O3, SiN x 、SiON x 、TiO x These passivation materials have good passivation effects, can effectively reduce the dangling bonds on the silicon surface, reduce the surface state density, and thus reduce the recombination of carriers on the surface.

[0037] In some embodiments, in order to enhance the passivation effect, the first passivation layer may include a plurality of sub-passivation layers stacked in sequence. For example, the first passivation layer includes an Al2O3 layer, a SiN x Layer, SiONx layer, TiO x In some other embodiments, in order to enhance the passivation effect, the second passivation layer may include a plurality of sub-passivation layers stacked in sequence, for example, the second passivation layer includes an Al2O3 layer, a SiN x Layer, SiON x layer, TiO x At least two of the layers, the stacking order is not limited here.

[0038] In an optional embodiment, the material of the first passivation layer includes Al2O3, SiN x 、SiON x 、TiO x One or more of; The material of the second passivation layer includes SiN x 、SiON x One or both of the following.

[0039] The first passivation layer is close to the silicon substrate. The Al2O3 and SiN x 、SiON x and TiO x It has a good interface passivation effect, which can reduce the recombination of carriers on the surface; the second passivation layer is far away from the silicon substrate, and the SiN x and SiON x It not only has a good interface passivation effect, but also has a wider refractive index adjustment range, has a better anti-reflection effect, and improves light absorption efficiency.

[0040] In an optional embodiment, the material of the first TCO layer includes one or more of fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, aluminum-gallium co-doped zinc oxide, aluminum-titanium co-doped zinc oxide, indium tin oxide, and titanium oxide. These TCO layer materials have high transparency and good electrical conductivity, which can ensure that the incident light is fully absorbed by the cell and ensure the photoelectric conversion efficiency of the cell.

[0041] In an optional embodiment, the mass percentage of fluorine element in the fluorine-doped tin oxide is 0.1-20%; (for example, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0042] In an optional embodiment, the mass percentage of antimony element in the antimony-doped tin oxide is 0.1-20% (eg, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0043] In an optional embodiment, the mass percentage of aluminum element in aluminum-doped zinc oxide is 0.1-20% (for example, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0044] In an optional embodiment, the mass percentage of gallium element in the gallium-doped zinc oxide is 0.1-20% (for example, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0045] In an optional embodiment, the mass percentage of boron in the boron-doped zinc oxide is 0.1-20% (eg, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0046] In an optional embodiment, in the aluminum-gallium co-doped zinc oxide, the total mass percentage of aluminum and gallium elements is 1-20% (for example, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0047] In an optional embodiment, in the aluminum-titanium co-doped zinc oxide, the total mass percentage of aluminum and titanium is 1-20% (eg, 0.1%, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18% or 20%).

[0048] TCO layer materials with doping elements can effectively adjust the conductivity of the TCO layer and optimize the anti-PID performance of the battery. However, if the doping element content is too low, the conductivity of the TCO layer is poor; if the doping element content is too high, its conductivity will not increase, but will increase the difficulty of the preparation process and increase production costs; when the content of the doping element in the TCO layer material is appropriate, the TCO layer material can have both excellent conductivity and low production costs.

[0049] In some embodiments, the thickness of the first TCO layer is 0.1-50nm. When the thickness of the first TCO layer is less than 0.1nm, it cannot effectively block alkali metal ions and has no anti-PID effect; when the thickness of the first TCO layer is greater than 50nm, the parasitic absorption of the TCO layer will increase, the photoelectric conversion efficiency of the battery will be reduced, and the light transmittance of the battery will be reduced; when the thickness of the first TCO layer is 0.1-50nm, the battery has good anti-PID effect and photoelectric conversion efficiency. Specifically, the thickness of the first TCO layer can be 0.1nm, 1nm, 3nm, 5nm, 10nm, 20nm, 30nm, 40nm or 50nm.

[0050] In an optional embodiment, the square resistance of the first TCO layer is 1Ω / sq-10 6Ω / sq. In some embodiments, in order to ensure the conductivity of the TCO layer, the square resistance of the first TCO layer can be controlled to be 1Ω / sq-200Ω / sq. Specifically, the square resistance of the first TCO layer can be 1Ω / sq, 10Ω / sq, 20Ω / sq, 50Ω / sq, 80Ω / sq, 100Ω / sq, 150Ω / sq or 200Ω / sq.

[0051] In the present application, the solar cell may be a TOPCon (Tunneling Oxide Passivation Contact) solar cell or a BC (Back Contact) solar cell, which is not specifically limited herein.

[0052] In an optional embodiment, the solar cell is a TOPCon solar cell; the TOPCon solar cell also includes: a first tunneling oxide layer and a first doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer.

[0053] In an optional embodiment, the first tunneling oxide layer and the first doped polysilicon layer in the TOPCon solar cell are only located in the metal region, the non-metal region does not have the first tunneling oxide layer and the first doped polysilicon layer, and the first passivation layer located in the non-metal region is in contact with the silicon substrate.

[0054] In an optional embodiment, the solar cell is a BC (back contact) solar cell; the BC solar cell also includes a first region and a second region located on a first surface of the silicon substrate, the first region and the second region are staggered and spaced apart from each other; the first region includes: a second tunneling oxide layer and a second doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the second region includes: a third tunneling oxide layer and a third doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along the first direction; the doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; the doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

[0055] like Figure 1 and Figure 5 As shown, in an optional embodiment, the solar cell further comprises: A third passivation layer 310, a second TCO layer 320, and a fourth passivation layer 330 are sequentially stacked on the second surface of the silicon substrate 100 and along the second direction D2; The second direction D2 is opposite to the first direction D1.

[0056] The anti-PID effect can be further improved by forming a stacked passivation structure (ie, a passivation layer, a TCO layer, and a passivation layer stacked in sequence) on both sides of the silicon substrate.

[0057] In some embodiments, the material of the first passivation layer and the material of the second passivation layer respectively and independently include Al2O3, SiN x 、SiON x 、TiO x In some embodiments, the material of the second TCO layer includes one or more of fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, aluminum-gallium co-doped zinc oxide, aluminum-titanium co-doped zinc oxide, indium tin oxide, and titanium oxide.

[0058] like Figure 1 As shown, in an optional embodiment, the solar cell is a TOPCon solar cell; the TOPCon solar cell also includes: a diffused doping layer 470 located between the silicon substrate 100 and the first passivation layer 210; A third passivation layer 310 and a fourth passivation layer 330 are located on the second surface of the silicon substrate 100 and are sequentially stacked along the second direction D2; and A first tunneling oxide layer 410 and a first doped polysilicon layer 420 are located between the silicon substrate 100 and the third passivation layer 310 and are sequentially stacked along the second direction D2; Wherein, the doping type of the silicon substrate 100 is opposite to the doping type of the diffusion doping layer 470; The doping type of the silicon substrate 100 is the same as the doping type of the first doped polysilicon layer 420 .

[0059] The doping type of the silicon substrate is opposite to the doping type of the diffusion doping layer, and the silicon substrate and the diffusion doping layer form a PN junction.

[0060] like Figure 1 As shown, in an optional embodiment, the first tunneling oxide layer 410 and the first doped polysilicon layer 420 in the TOPCon solar cell may be located only in the metal region, the non-metal region does not have the first tunneling oxide layer and the first doped polysilicon layer, and the third passivation layer 310 located in the non-metal region is in contact with the silicon substrate 100.

[0061] like Figure 5 As shown, in an optional embodiment, the solar cell is a BC solar cell; the BC solar cell also includes: A third passivation layer 310 and a fourth passivation layer 330 are located on the second surface of the silicon substrate 100 and are sequentially stacked along the second direction D2; and A first region 510 and a second region 520 are located on the second surface of the silicon substrate 100, wherein the first region 510 and the second region 520 are staggered and spaced apart from each other; The first region 510 includes: a second tunneling oxide layer 430 and a second doped polysilicon layer 440 which are located between the silicon substrate 100 and the third passivation layer 310 and are sequentially stacked along the second direction D2; The second region 520 includes: a third tunneling oxide layer 450 and a third doped polysilicon layer 460 which are located between the silicon substrate 100 and the third passivation layer 310 and are sequentially stacked along the second direction D2; The doping type of the silicon substrate 100 is opposite to the doping type of the second doped polysilicon layer 440 ; The doping type of the silicon substrate 100 is the same as the doping type of the third doped polysilicon layer 460 .

[0062] The doping type of the silicon substrate is opposite to that of the second doped polysilicon layer, forming a PN junction, and the second doped polysilicon layer is an emitter. The doping type of the silicon substrate is the same as that of the third doped polysilicon layer, and the third doped polysilicon layer is a back surface field.

[0063] In some embodiments, the solar cell further includes an electrode.

[0064] like Figure 1 As shown, in some embodiments, the solar cell is a TOPCon solar cell, and the TOPCon solar cell includes: a first electrode 610 located on a first surface of the silicon substrate 100 , and a second electrode 620 located on a second surface of the silicon substrate 100 .

[0065] like Figure 5 As shown, in some embodiments, the solar cell is a BC solar cell, and the BC solar cell includes: a first electrode 610 located on the first region 510 , and a second electrode 620 located on the second region 520 .

[0066] In some embodiments, the first electrode and the second electrode may respectively and independently include one or more of Au, Ag, Al, and Cu.

[0067] The present application provides a method for preparing a solar cell provided in any one of the above embodiments, comprising: Step S110: providing a silicon substrate, wherein the silicon substrate comprises a first surface and a second surface that are oppositely disposed; Step S120: a first passivation layer, a first TCO layer, and a second passivation layer are sequentially stacked on the first surface of the silicon substrate and along a first direction.

[0068] In step S110, the provided silicon substrate may be an N-type silicon substrate or a P-type silicon substrate, which is not specifically limited here.

[0069] In step S120, a first passivation layer may be formed on the first surface of the silicon substrate by an atomic layer deposition (ALD) method or a plasma enhanced chemical vapor deposition (PECVD) method; a first TCO layer may be formed on the first passivation layer by a plasma enhanced chemical vapor deposition (PECVD) method, a physical vapor deposition (PVD) method or an atomic layer deposition (ALD) method; and a second passivation layer may be formed on the first TCO layer by an atomic layer deposition (ALD) method or a plasma enhanced chemical vapor deposition (PECVD) method.

[0070] In some embodiments, before step S120 , the method for preparing a solar cell further includes: step S130 : forming a diffusion doping layer on the silicon substrate.

[0071] In step S130 , an ion implantation method or a plasma enhanced chemical vapor deposition (PECVD) method may be used to form a diffusion doping layer on the silicon substrate.

[0072] In some embodiments, before step S120, the method for preparing a solar cell also includes: step S140: forming a first tunneling oxide layer and a first doped polysilicon layer stacked in sequence along a first direction on a silicon substrate; wherein the doping type of the silicon substrate is opposite to the doping type of the diffusion doping layer; and the doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer.

[0073] In step S140, an atomic layer deposition (ALD) method or a chemical vapor deposition (CVD) method may be used to form a first tunneling oxide layer on the silicon substrate, and the material of the first tunneling oxide layer is SiO2; a plasma enhanced chemical vapor deposition (PECVD) method or a physical vapor deposition (PVD) method may be used to form a first doped polysilicon layer on the first tunneling oxide layer.

[0074] In an optional embodiment, after forming the first tunneling oxide layer and the first doped polysilicon layer, step S140 further includes: removing the first tunneling oxide layer and the first doped polysilicon layer in the non-metallic area of ​​the silicon wafer, and retaining the first tunneling oxide layer and the first doped polysilicon layer in the metal area.

[0075] In some embodiments, before step S120, the method for preparing a solar cell further includes: step S150: forming a second tunneling oxide layer and a third tunneling oxide layer that are staggered and spaced apart from each other on the first surface of the silicon substrate; forming a second doped polysilicon layer on the second tunneling oxide layer, the second tunneling oxide layer and the second doped polysilicon layer together constitute the first region; forming a third doped polysilicon layer on the third tunneling oxide layer, the third tunneling oxide layer and the third doped polysilicon layer together constitute the second region; The doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; the doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

[0076] In step S150, a second tunnel oxide layer and a third tunnel oxide layer may be formed on the silicon substrate by atomic layer deposition (ALD) or chemical vapor deposition (CVD), and the materials of the second tunnel oxide layer and the third tunnel oxide layer are both SiO2; a second doped polysilicon layer may be formed by plasma enhanced chemical vapor deposition (PECVD) or physical vapor deposition (PVD); and a third doped polysilicon layer may be formed by plasma enhanced chemical vapor deposition (PECVD) or physical vapor deposition (PVD).

[0077] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0078] Example 1 like Figure 1 As shown, the specific structure of the solar cell of Example 1 includes: A silicon substrate 100, the silicon substrate 100 comprises a first surface and a second surface which are arranged opposite to each other, and the silicon substrate 100 is an N-type silicon substrate; A diffusion doping layer 470 (a P-type diffusion doping layer, with a doping element of boron), a first passivation layer 210, a first TCO layer 220, a second passivation layer 230, and a first electrode 610 are sequentially stacked on the first surface of the silicon substrate 100 and along the first direction D1; wherein the first electrode 610 penetrates the first passivation layer 210, the first TCO layer 220, and the second passivation layer 230 and contacts the diffusion doping layer 470; A first tunneling oxide layer 410, a first doped polysilicon layer 420 (N-type doped polysilicon layer), a third passivation layer 310, a second TCO layer 320, a fourth passivation layer 330, and a second electrode 620 are sequentially stacked on the second surface of the silicon substrate 100 and along the second direction D2; wherein the second electrode 620 penetrates the third passivation layer 310, the second TCO layer 320 and the fourth passivation layer 330 and contacts with the first doped polysilicon layer 420.

[0079] The method for preparing a solar cell of embodiment 1 comprises: Step S201: providing a silicon substrate, wherein the silicon substrate comprises a first surface and a second surface arranged opposite to each other, and the silicon substrate is an N-type silicon substrate; Step S202: preparing a suede structure on the first surface of the silicon substrate; Step S203: forming a diffusion doping layer on the first surface of the silicon substrate, wherein the doping element in the diffusion doping layer is boron; Step S204: forming a first tunneling oxide layer and a first doped polysilicon layer by diffusion in sequence on the second surface of the silicon substrate, wherein the doping element of the first doped polysilicon layer is phosphorus; Step S205: using a mixed solution of KOH and additives to remove the first tunneling oxide layer and the first doped polysilicon layer in the non-metallic region of the second surface of the silicon substrate; Step S206: using an ALD method, trimethylaluminum (TMA) and H2O form a first passivation layer with a thickness of 4 nm on the diffusion doped layer, and a third passivation layer with a thickness of 4 nm is formed on the surface of the first doped polysilicon layer and the exposed second surface of the silicon substrate, wherein the material of the first passivation layer and the third passivation layer is Al2O3; Step S207: using an ALD method to form a first TCO layer with a thickness of 5 nm on the first passivation layer using diethyl zinc (DEZ), TMA and H2O, wherein the material of the first TCO layer is aluminum-doped zinc oxide (the mass percentage of aluminum is 5%); Step S208: using an ALD method, diethyl zinc (DEZ), TMA, titanium tetrachloride (TiCl4) and H2O are used to form a second TCO layer with a thickness of 2 nm on the third passivation layer, wherein the material of the second TCO layer is aluminum-titanium co-doped zinc oxide (the total mass percentage of aluminum and titanium is 8%); Step S209: Using PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 90nm on the first TCO layer, and a fourth passivation layer with a thickness of 90nm on the second TCO layer. The materials of the second passivation layer and the fourth passivation layer are SiN x ; Step S210: Print a conductive paste on the fourth passivation layer and the second passivation layer by screen printing, and after sintering, form a second electrode that penetrates the third passivation layer, the second TCO layer, and the fourth passivation layer and contacts the first doped polysilicon layer, and a first electrode that penetrates the first passivation layer, the first TCO layer, and the second passivation layer and contacts the diffused doped layer.

[0080] Example 2 like Figure 2 As shown, the solar cell of Example 2 has a similar structure to the solar cell of Example 1, except that the solar cell of Example 2 does not have a second TCO layer.

[0081] The solar cell of Example 2 is prepared by a preparation method similar to that of Example 1, except that the preparation method of the solar cell of Example 2 does not include step S208; and Step S209 is: using PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 95nm on the first TCO layer, and a fourth passivation layer with a thickness of 90nm is formed on the third passivation layer. The materials of the second passivation layer and the fourth passivation layer are SiN x ; Step S210 is: printing a conductive paste on the fourth passivation layer and the second passivation layer by screen printing, and after sintering, forming a second electrode that penetrates the third passivation layer, the fourth passivation layer and contacts the first doped polysilicon layer, and a first electrode that penetrates the first passivation layer, the first TCO layer, the second passivation layer and contacts the diffused doped layer.

[0082] Example 3 like Figure 3 As shown, the solar cell of Example 3 has a similar structure to the solar cell of Example 1, except that the solar cell of Example 3 does not have the first TCO layer.

[0083] The solar cell of Example 3 is prepared by a preparation method similar to that of Example 1, except that the preparation method of the solar cell of Example 3 does not include step S207; and Step S209: Using PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 90nm on the first passivation layer, and a fourth passivation layer with a thickness of 95nm on the second TCO layer. The materials of the second passivation layer and the fourth passivation layer are SiN x ; Step S210: Print a conductive paste on the fourth passivation layer and the second passivation layer by screen printing, and after sintering, form a second electrode that penetrates the third passivation layer, the second TCO layer, and the fourth passivation layer and contacts the first doped polysilicon layer, and a first electrode that penetrates the first passivation layer, the second passivation layer and contacts the diffusion doped layer.

[0084] Example 4 like Figure 4 As shown, the solar cell of Example 4 has a similar structure to that of the solar cell of Example 1, except that the first TCO layer 220 in the solar cell of Example 4 includes a first sub-TCO layer 221, a second sub-TCO layer 222, and a third sub-TCO layer 223 stacked along a first direction D1.

[0085] The solar cell of Example 4 was prepared by a preparation method similar to that of Example 1, except that, in the preparation method of the solar cell of Example 4, step S207 is: using the ALD method, DEZ, TMA, titanium tetrachloride (TiCl4) and H2O form a first sub-TCO layer with a thickness of 3 nm on the first passivation layer, and the material of the first sub-TCO layer is aluminum-titanium co-doped zinc oxide (the total mass percentage of aluminum and titanium is 4%); using the ALD method, DEZ, trimethylgallium (TMGa) and H2O form a second sub-TCO layer with a thickness of 4 nm on the first sub-TCO layer, and the material of the second sub-TCO layer is gallium-doped zinc oxide (the mass percentage of gallium is 2.5%); using the ALD method, DEZ, TMA and H2O form a third sub-TCO layer with a thickness of 3 nm on the second sub-TCO layer, and the material of the third sub-TCO layer is aluminum-doped zinc oxide (the mass percentage of aluminum is 3%); the first sub-TCO layer, the second sub-TCO layer and the third sub-TCO layer together constitute the first TCO layer.

[0086] Example 5 The solar cell of Example 5 has the same structure as the solar cell of Example 1.

[0087] The solar cell of Example 5 was prepared by a preparation method similar to that of Example 1, except that, in the preparation method of the solar cell of Example 5, step S207 is: using the ALD method to form a first TCO layer with a thickness of 7 nm on the first passivation layer using diethyl zinc (DEZ), TMA and H2O, and the material of the first TCO layer is aluminum-doped zinc oxide (the mass percentage of aluminum is 2%).

[0088] Example 6 The solar cell of Example 6 has the same structure as the solar cell of Example 1.

[0089] The solar cell of Example 6 was prepared by a preparation method similar to that of Example 1, except that, in the preparation method of the solar cell of Example 6, step S207 is: using the ALD method, tetrabutyltin (TBTO), trimethylantimony (TMA) and H2O form a first TCO layer with a thickness of 3 nm on the first passivation layer, and the material of the first TCO layer is antimony-doped tin oxide (the mass percentage of antimony is 5%).

[0090] Example 7 like Figure 5 As shown, the specific structure of the solar cell of Example 7 includes: A silicon substrate 100, the silicon substrate 100 comprises a first surface and a second surface which are arranged opposite to each other, and the silicon substrate 100 is an N-type silicon substrate; A first passivation layer 210, a first TCO layer 220, and a second passivation layer 230 are sequentially stacked on the first surface of the silicon substrate 100 and along the first direction D1; A first region 510 and a second region 520 are arranged alternately and spaced from each other on the second surface of the silicon substrate 100; the first region 510 includes: a second tunneling oxide layer 430 and a second doped polysilicon layer 440 (P-type doped polysilicon layer) are arranged between the silicon substrate 100 and the third passivation layer 310 and are stacked in sequence along the second direction D2; the second region 520 includes: a third tunneling oxide layer 450 and a third doped polysilicon layer 460 (N-type doped polysilicon layer) are arranged between the silicon substrate 100 and the third passivation layer 310 and are stacked in sequence along the second direction D2; A third passivation layer 310, a second TCO layer 320, and a fourth passivation layer 330 are located on the second doped polysilicon layer 440 and the third doped polysilicon layer 460 and are sequentially stacked along the second direction D2; A first electrode 610 penetrating the third passivation layer 310 , the second TCO layer 320 , and the fourth passivation layer 330 and contacting the second doped polysilicon layer 440 ; The second electrode 620 penetrates the third passivation layer 310 , the second TCO layer 320 , and the fourth passivation layer 330 and contacts the third doped polysilicon layer 460 .

[0091] The method for preparing a solar cell of embodiment 7 comprises: Step S301: providing a silicon substrate, wherein the silicon substrate comprises a first surface and a second surface arranged opposite to each other, and the silicon substrate is an N-type silicon substrate; Step S302: using an ALD method to form a second tunneling oxide layer and a third tunneling oxide layer that are staggered and spaced apart on the second surface of the silicon substrate with silane and oxygen; Step S303: using PECVD method to form a second doped polysilicon layer on the second tunnel oxide layer using hydrogen, silane and borane; the second doped polysilicon layer is a P-type doped polysilicon layer; the second tunnel oxide layer and the second doped polysilicon layer together constitute the first region; A PECVD method is used to form a third doped polysilicon layer on the third tunnel oxide layer using hydrogen, silane and phosphine; the third doped polysilicon layer is an N-type doped polysilicon layer; the third tunnel oxide layer and the third doped polysilicon layer together constitute the second region; Step S304: using an ALD method to form a first passivation layer with a thickness of 4 nm on the first surface of the silicon substrate using trimethylaluminum (TMA) and H2O, wherein the material of the first passivation layer is Al2O3; Step S305: using an ALD method to form a third passivation layer with a thickness of 5 nm on the second doped polysilicon layer and the third doped polysilicon layer using trimethylaluminum (TMA) and H2O, wherein the material of the third passivation layer is Al2O3; Step S306: using an ALD method to form a first TCO layer with a thickness of 5 nm on the first passivation layer using diethyl zinc (DEZ), TMA and H2O, wherein the material of the first TCO layer is aluminum-doped zinc oxide (the mass percentage of aluminum is 5%); Step S307: using an ALD method, diethyl zinc (DEZ), TMA, titanium tetrachloride (TiCl4) and H2O are used to form a second TCO layer with a thickness of 2 nm on the third passivation layer, wherein the material of the second TCO layer is aluminum-titanium co-doped zinc oxide (the total mass percentage of aluminum and titanium is 8%); Step S308: Using PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 95 nm on the first TCO layer. The material of the second passivation layer is SiN x ; Step S309: Using PECVD method, silane and ammonia are used to form a fourth passivation layer with a thickness of 105 nm on the second TCO layer. The material of the fourth passivation layer is SiN x ; Step S310: printing a conductive paste on the fourth passivation layer corresponding to the first area by screen printing, and sintering to form a first electrode penetrating the third passivation layer, the second TCO layer and the fourth passivation layer and contacting the second doped polysilicon layer; Conductive paste is printed on the fourth passivation layer corresponding to the second area by screen printing, and sintered to form a second electrode penetrating the third passivation layer, the second TCO layer, the fourth passivation layer and contacting the third doped polysilicon layer.

[0092] Example 8 like Figure 6 As shown, the solar cell of Example 8 has a similar structure to the solar cell of Example 7, except that the solar cell of Example 8 does not have a second TCO layer.

[0093] The solar cell of Example 8 is prepared by a preparation method similar to that of Example 7, except that the preparation method of the solar cell of Example 8 does not include step S307, and step S309 is: using PECVD method, silane and ammonia are used to form a fourth passivation layer with a thickness of 95 nm on the third passivation layer, and the material of the fourth passivation layer is SiN x .

[0094] Example 9 like Figure 7As shown, the solar cell of Example 9 has a similar structure to the solar cell of Example 7, except that the solar cell of Example 9 does not have the first TCO layer.

[0095] The solar cell of Example 9 is prepared by a preparation method similar to that of Example 7, except that the preparation method of the solar cell of Example 9 does not include step S306, and step S308 is: using PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 95 nm on the first passivation layer, and the material of the second passivation layer is SiN x .

[0096] Example 10 like Figure 8 As shown, the solar cell of Example 10 has a similar structure to the solar cell of Example 7, except that the first TCO layer 220 in the solar cell of Example 10 includes a first sub-TCO layer 221, a second sub-TCO layer 222, and a third sub-TCO layer 223 stacked along a first direction D1.

[0097] The solar cell of Example 10 was prepared by a preparation method similar to that of Example 7, except that, in the preparation method of the solar cell of Example 10, step S306 is as follows: DEZ, TMA, titanium tetrachloride (TiCl4) and H2O were used to form a first sub-TCO layer with a thickness of 4 nm on the first passivation layer by using the ALD method, and the material of the first sub-TCO layer was aluminum-titanium co-doped zinc oxide (the total mass percentage of aluminum and titanium was 4%); DEZ, trimethylgallium (TMGa) and H2O were used to form a second sub-TCO layer with a thickness of 6 nm on the first sub-TCO layer by using the ALD method, and the material of the second sub-TCO layer was gallium-doped zinc oxide (the mass percentage of gallium was 2%); DEZ, TMA and H2O were used to form a third sub-TCO layer with a thickness of 2 nm on the second sub-TCO layer by using the ALD method, and the material of the third sub-TCO layer was aluminum-doped zinc oxide (the mass percentage of aluminum was 3%); the first sub-TCO layer, the second sub-TCO layer and the third sub-TCO layer together constituted the first TCO layer.

[0098] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the specific structures and preparation methods of the solar cells of Comparative Examples 1 and 2.

[0099] Comparative Example 1 The solar cell of Comparative Example 1 has a similar structure to that of the solar cell of Example 1, except that the solar cell of Comparative Example 1 does not have the first TCO layer and the second TCO layer.

[0100] The solar cell of Comparative Example 1 is prepared by a preparation method similar to that of Example 1, except that the preparation method of the solar cell of Comparative Example 1 does not include step S207 and step S208, and step S209 is: using a PECVD method, silane and ammonia are used to form a second passivation layer with a thickness of 90 nm on the first passivation layer, and silane and ammonia are used to form a fourth passivation layer with a thickness of 90 nm on the third passivation layer, and the materials of the second passivation layer and the fourth passivation layer are SiN x .

[0101] Comparative Example 2 The solar cell of Comparative Example 2 has a similar structure to that of the solar cell of Example 7, except that the solar cell of Comparative Example 2 does not have the first TCO layer and the second TCO layer.

[0102] The solar cell of Comparative Example 2 is prepared by a preparation method similar to that of Example 7, except that the preparation method of the solar cell of Comparative Example 2 does not include step S306 and step S307, and step S308 is: using a PECVD method to form a second passivation layer with a thickness of 100 nm on the first passivation layer with silane and ammonia, and the material of the second passivation layer is SiN x Step S309 is: using PECVD method, silane and ammonia are used to form a fourth passivation layer with a thickness of 95nm on the third passivation layer. The material of the fourth passivation layer is SiN x .

[0103] The present application also manufactures the solar cells in Examples 1 to 10 and Comparative Examples 1 to 2 into corresponding photovoltaic modules, and performs PID96 attenuation test to obtain power attenuation value ΔP. The relevant test results are shown in Table 1.

[0104] Table 1

[0105] Table 1 (continued)

[0106] From the data in Table 1, it can be seen that compared with Comparative Example 1 and Comparative Example 2, the photovoltaic modules made of the solar cells in Examples 1 to 10 of the present application have a lower power attenuation value, and the power attenuation value of the module after PID 96h is less than 5%, which meets the IEC (International Electrotechnical Commission) standard. This shows that compared with conventional battery modules, the photovoltaic modules made of the solar cells in Examples 1 to 10 of the present application have a good anti-PID effect.

[0107] In summary, the solar cell of the present application forms a stacked passivation structure by sequentially stacking a first passivation layer, a first TCO (transparent conductive oxide) layer and a second passivation layer on a silicon substrate. The TCO layer has a tight texture and can effectively block alkali metal ions from entering the interior of the silicon substrate; moreover, the TCO layer has good conductivity and, as a charge transmission channel, can quickly conduct away the charges accumulated on the surface of the battery, thereby effectively solving the potential induced decay (PID) problem and having a good anti-PID effect. In addition, the TCO layer is located between the two passivation layers, so that the TCO layer does not directly contact the silicon substrate, which can avoid the increase in the interface defect state density caused by lattice mismatch; the second passivation layer is provided, so that the TCO layer can be encapsulated and protected to prevent pollutants such as water vapor from damaging the TCO layer. In short, the solar cell of the present application can effectively solve the PID problem and has a good anti-PID effect.

[0108] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0109] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0110] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0111] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0112] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A solar cell, characterized in that: include: A silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; A first passivation layer, a first TCO layer, and a second passivation layer are sequentially stacked on the first surface of the silicon substrate and along a first direction.

2. The solar cell according to claim 1, characterized in that The first TCO layer includes a plurality of sub-TCO layers stacked along a first direction; The refractive index of the sub-TCO layer close to the silicon substrate is greater than the refractive index of the sub-TCO layer far from the silicon substrate.

3. The solar cell according to claim 1, characterized in that The first TCO layer includes a first sub-TCO layer, a second sub-TCO layer, and a third sub-TCO layer stacked along a first direction; Wherein, the refractive index of the first sub-TCO layer is greater than the refractive index of the second sub-TCO layer; The refractive index of the second sub-TCO layer is greater than the refractive index of the third sub-TCO layer.

4. The solar cell according to claim 3, characterized in that: The material of the first sub-TCO layer is aluminum-titanium co-doped zinc oxide, wherein the total mass percentage of aluminum and titanium is 0.1-5%; the material of the second sub-TCO layer is gallium-doped zinc oxide, wherein the mass percentage of gallium is 0.1-3%; the material of the third sub-TCO layer is aluminum-doped zinc oxide, wherein the mass percentage of aluminum is 0.1-5%.

5. The solar cell according to claim 3, characterized in that: The refractive index of the first sub-TCO layer is 1.9-2.2, the refractive index of the second sub-TCO layer is 1.8-2.1, and the refractive index of the third sub-TCO layer is 1.7-2.

0.

6. The solar cell according to claim 1, characterized in that The material of the first passivation layer and the material of the second passivation layer respectively and independently include Al2O3, SiN x 、SiON x 、TiO x One or more of .

7. The solar cell according to claim 1, characterized in that The material of the first passivation layer includes Al2O3, SiN x 、SiON x 、TiO x One or more of; The material of the second passivation layer includes SiN x 、SiON x One or both of the following.

8. The solar cell according to claim 1, characterized in that The material of the first TCO layer includes one or more of fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, boron-doped zinc oxide, aluminum-gallium co-doped zinc oxide, aluminum-titanium co-doped zinc oxide, indium tin oxide, and titanium oxide.

9. The solar cell according to claim 8, characterized in that In the fluorine-doped tin oxide, the mass percentage of fluorine element is 0.1-20%; The mass percentage of antimony element in the antimony-doped tin oxide is 0.1-20%; The mass percentage of aluminum in the aluminum-doped zinc oxide is 0.1-20%; In the gallium-doped zinc oxide, the mass percentage of gallium element is 0.1-20%; The mass percentage of boron in the boron-doped zinc oxide is 0.1-20%; In the aluminum-gallium co-doped zinc oxide, the total mass percentage of aluminum and gallium is 1-20%; In the aluminum-titanium co-doped zinc oxide, the total mass percentage of aluminum and titanium is 1-20%.

10. The solar cell according to claim 1, characterized in that: The sheet resistance of the first TCO layer is 1Ω / sq-10 6 Ω / sq.

11. The solar cell according to any one of claims 1 to 10, characterized in that: The solar cell is a TOPCon solar cell; the TOPCon solar cell further comprises: a first tunneling oxide layer and a first doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer; or The solar cell is a BC solar cell; the BC solar cell also includes a first region and a second region located on a first surface of a silicon substrate, the first region and the second region are staggered and spaced from each other; the first region includes: a second tunneling oxide layer and a second doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along a first direction; the second region includes: a third tunneling oxide layer and a third doped polysilicon layer located between the silicon substrate and the first passivation layer and stacked in sequence along the first direction; the doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; the doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

12. The solar cell according to any one of claims 1 to 10, characterized in that: Also includes: A third passivation layer, a second TCO layer, and a fourth passivation layer are sequentially stacked on the second surface of the silicon substrate and along the second direction; The second direction is opposite to the first direction.

13. The solar cell according to any one of claims 1 to 10, characterized in that: The solar cell is a TOPCon solar cell; The TOPCon solar cell further comprises: a diffusion doping layer between the silicon substrate and the first passivation layer; a third passivation layer and a fourth passivation layer located on the second surface of the silicon substrate and sequentially stacked along a second direction; and A first tunneling oxide layer and a first doped polysilicon layer are located between the silicon substrate and the third passivation layer and are sequentially stacked along the second direction; Wherein, the doping type of the silicon substrate is opposite to the doping type of the diffusion doping layer; The doping type of the silicon substrate is the same as the doping type of the first doped polysilicon layer.

14. The solar cell according to any one of claims 1 to 10, characterized in that: The solar cell is a BC solar cell; The BC solar cell further comprises: A third passivation layer and a fourth passivation layer are located on the second surface of the silicon substrate and are sequentially stacked along the second direction; and A first region and a second region located on the second surface of the silicon substrate, wherein the first region and the second region are staggered and spaced from each other; The first region includes: a second tunneling oxide layer and a second doped polysilicon layer located between the silicon substrate and the third passivation layer and stacked in sequence along the second direction; The second region includes: a third tunneling oxide layer and a third doped polysilicon layer located between the silicon substrate and the third passivation layer and stacked in sequence along the second direction; The doping type of the silicon substrate is opposite to the doping type of the second doped polysilicon layer; The doping type of the silicon substrate is the same as the doping type of the third doped polysilicon layer.

15. A method for preparing a solar cell according to any one of claims 1 to 14, characterized in that: include: Providing a silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; A first passivation layer, a first TCO layer, and a second passivation layer are sequentially stacked on the first surface of the silicon substrate and along a first direction.

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