Heterojunction solar cell and preparation method and application thereof

Abstract

The invention discloses a heterojunction solar cell and a preparation method and application thereof, and belongs to the technical field of new energy. The heterojunction solar cell comprises an Ag grid line, a second TCO layer, a P-type amorphous silicon layer, a second intrinsic amorphous silicon layer, an N-type crystalline silicon substrate layer, a first intrinsic amorphous silicon layer, an N-type amorphous silicon layer, a first TCO layer and an Ag grid line which are arranged in a stacked mode, the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer which are stacked in sequence, the TCO-I film layer makes contact with the P-type amorphous silicon layer, interface recombination can be reduced, and the contact area between the TCO-I film layer and the TCO-II film layer can be reduced. And the collection efficiency of current carriers is improved. The laminated structure of the TCO-I and the TCO-II has a better light trapping characteristic, the length of a light path is increased, the light absorption efficiency is improved, the contact effect of the TCO-II and the Ag grid line can be improved by the contact of the TCO-II film layer and the Ag grid line, and the carrier transmission efficiency is improved, so that the current is improved, and the photoelectric conversion efficiency of the cell is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and in particular to a heterojunction solar cell, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous progress of solar cell production technologies, the production cost has been continuously reduced, the conversion efficiency has been continuously improved, and the application of photovoltaic power generation has become increasingly widespread and has become an important energy source for power supply. Among them, heterojunction solar cells (Heterojunction with Intrinsic Thin-layer, abbreviated as HJT) have developed rapidly due to characteristics such as low preparation temperature, high conversion efficiency, and low attenuation.

[0003] In the prior art, taking an N-type crystalline silicon substrate as an example, the structure of an HJT cell includes: grid electrode / transparent conductive oxide / P-type amorphous silicon layer / intrinsic amorphous silicon layer / N-type crystalline silicon substrate / intrinsic amorphous silicon layer / N-type amorphous silicon layer / transparent conductive oxide / grid electrode, where the transparent conductive oxide layer is a single-layer structure. Since the amorphous silicon layer crystals have a disordered structure, the electron and hole migration rates are low, and the lateral conductivity is poor, which is not conducive to the collection of photo-generated carriers. Therefore, during the production of HJT, a transparent conductive oxide (abbreviated as TCO) thin film is added between the electrode and the amorphous silicon layer, which can effectively increase the collection of carriers. The TCO thin film has dual functions of optical transparency and conductivity, plays a key role in the collection of carriers, can reduce light reflection, plays a good light-trapping role, and is an excellent window layer material. However, the light transmittance and conductivity of TCO are two contradictory aspects. When selecting a TCO material, the battery efficiency is usually used as a measurement standard, and a balance point is selected between the light transmittance and conductivity of the material. The limitations of existing TCO materials have become an obstacle to the improvement of solar cell efficiency, and how to improve the performance of TCO materials has become a new research topic. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a heterojunction solar cell. Compared with the ordinary TCO thin film in a conventional heterojunction solar cell, the contact between the TCO-I film layer and the P-type amorphous silicon layer can improve the contact effect between the TCO-I and the P-type amorphous silicon layer, reduce interface recombination, and improve the collection efficiency of carriers. The stacked structure of TCO-I and TCO-II has better light-trapping characteristics, increases the optical path length, and improves the light absorption efficiency. The contact between the TCO-II film layer and the Ag grid line can improve the contact effect between the TCO-II and the Ag grid line, improve the carrier transport efficiency, thereby increasing the current and improving the photoelectric conversion efficiency of the battery. The present invention also provides a preparation method for the above-mentioned heterojunction solar cell.

[0005] The present invention also provides an application of the above heterojunction solar cell.

[0006] According to an embodiment of the first aspect of the present invention, a heterojunction solar cell is proposed. The heterojunction solar cell includes an Ag grid line, a second TCO layer, a P-type amorphous silicon layer, a second intrinsic amorphous silicon layer, an N-type crystalline silicon substrate layer, a first intrinsic amorphous silicon layer, an N-type amorphous silicon layer, a first TCO layer, and an Ag grid line which are stacked;

[0007] Wherein, the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer which are stacked in sequence,

[0008] The components of the TCO-I film layer include: In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:(M + N):N, where 0.0307 < M ≤ 0.1228 and 0.18 < N < 0.79.

[0009] The components of the TCO-II film layer include: In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:(X + Y):Y, where 0.0307 < X ≤ 0.1228 and 0 ≤ Y < 0.05.

[0010] According to the embodiment of the first aspect of the present invention, it has at least the following beneficial effects:

[0011] In order to improve the contact between the TCO layer and the P-type amorphous silicon layer, and the contact between the TCO layer and the electrode, the present invention changes the second TCO layer to a stacked structure. The second TCO layer is composed of a TCO-I film layer and a TCO-II film layer which are stacked in sequence.

[0012] The TCO-I film layer is in contact with the P-type amorphous silicon layer, and the TCO-II film layer is in contact with the Ag grid line.

[0013] Compared with the ordinary TCO thin film in the conventional heterojunction solar cell, the contact between the TCO-I film layer and the P-type amorphous silicon layer can improve the contact effect between the TCO-I and the P-type amorphous silicon layer, reduce interface recombination, and improve the carrier collection efficiency. The stacked structure of TCO-I and TCO-II has better light trapping characteristics, increases the light path length, and improves the light absorption efficiency. The contact between the TCO-II film layer and the Ag grid line can improve the contact effect between the TCO-II and the Ag grid line, and improve the carrier transport efficiency. Thereby increasing the current and improving the photoelectric conversion efficiency of the battery.

[0014] According to some embodiments of the present invention, the thickness of the TCO-I film layer is 60 - 80 nm.

[0015] When the thickness of the TCO-I film layer is in the range of 60 - 80 nm, it can optimize the interface contact, reduce the interface recombination; balance the conductivity and light transmittance; improve the light trapping effect, increase the light absorption, and cooperate with the TCO-II film layer to enhance the overall performance.

[0016] According to some embodiments of the present invention, the thickness of the TCO-II film layer is 20 - 40 nm.

[0017] The TCO-I film layer is mainly responsible for the interface contact with the P-type amorphous silicon layer and the light trapping effect, while the TCO-II film layer is mainly responsible for the contact with the Ag grid lines and the carrier transport. At the above thicknesses, the two cooperate to improve the battery performance.

[0018] According to some embodiments of the present invention, the material of the P-type amorphous silicon layer includes at least one of amorphous silicon, amorphous silicon carbide, amorphous silicon hydride, microcrystalline silicon, microcrystalline silicon carbide, and metal compound materials capable of doping.

[0019] According to some embodiments of the present invention, the material of the P-type amorphous silicon layer includes at least one of amorphous silicon hydride and microcrystalline silicon.

[0020] According to an embodiment of the second aspect of the present invention, a method for manufacturing a heterojunction solar cell is provided. The manufacturing method includes the following steps:

[0021] S1. Deposit first intrinsic amorphous silicon and second intrinsic amorphous silicon on both sides of the N-type crystalline silicon substrate by CVD respectively.

[0022] S2. Deposit the N-type amorphous silicon hydride layer on the outside of the first intrinsic amorphous silicon layer by CVD, and deposit the P-type amorphous silicon hydride layer on the outside of the second intrinsic amorphous silicon layer by CVD.

[0023] S3. Deposit a first TCO layer on the outside of the N-type amorphous silicon layer, and deposit a second TCO layer on the outside of the P-type amorphous silicon layer.

[0024] The deposition of the second TCO layer includes: sequentially forming a TCO-I film layer and a TCO-II film layer on the outside of the P-type amorphous silicon layer.

[0025] S4. Screen-print the Ag grid lines on the first TCO layer and the second TCO layer.

[0026] According to some embodiments of the present invention, in step S3, the deposition method includes at least one of physical vapor deposition and chemical vapor deposition.

[0027] According to some embodiments of the present invention, the physical vapor deposition includes at least one of magnetron sputtering and evaporation deposition.

[0028] According to some embodiments of the present invention, the physical vapor deposition includes a magnetron sputtering method.

[0029] According to some embodiments of the present invention, the magnetron sputtering includes at least one of direct current magnetron sputtering, direct current pulsed magnetron sputtering, and medium frequency magnetron sputtering.

[0030] According to some embodiments of the present invention, the atmosphere in the magnetron sputtering method includes at least two of argon, hydrogen, and oxygen.

[0031] According to some embodiments of the present invention, the atmosphere in the magnetron sputtering method includes argon and oxygen.

[0032] According to some embodiments of the present invention, in the magnetron sputtering method, the magnetic field intensity on the target surface is 500 Gs to 1500 Gs.

[0033] The above magnetic field intensity can effectively confine the plasma, improve the sputtering efficiency, and at the same time avoid local overheating of the target and uneven sputtering caused by too high a magnetic field intensity, form a dense and uniform TCO film layer, and reduce film layer defects.

[0034] According to some embodiments of the present invention, the sputtering gas pressure in the magnetron sputtering is 0.05 to 1 Pa.

[0035] The above sputtering gas pressure range can ensure that the sputtering particles have appropriate energy before reaching the substrate, form a dense and uniform TCO film layer, and improve the density and conductivity of the film layer.

[0036] According to some embodiments of the present invention, the power of the magnetron sputtering is 0.5 w / cm 2 ~3.5 w / cm 2 .

[0037] The sequentially stacked TCO-I film layer and TCO-II film layer prepared under the above conditions have at least the following beneficial effects: The contact between the TCO-I film layer and the p-type amorphous silicon layer can improve the contact effect between the TCO-I and the p-type amorphous silicon layer, reduce interface recombination, and improve the carrier collection efficiency. The stacked structure of the TCO-I film layer and the TCO-II film layer has better light trapping characteristics, increases the optical path length, and improves the light absorption efficiency. The contact between the TCO-II film layer and the Ag grid line can improve the contact effect between the TCO-II and the Ag grid line and improve the carrier transport efficiency. Thereby increasing the current and improving the photoelectric conversion efficiency of the battery. In addition, the preparation method of the stacked transparent conductive oxide thin film of the present invention is simple and easy to mass-produce.

[0038] According to some embodiments of the present invention, in the magnetron sputtering method, the magnetic field intensity on the target surface is 700 to 1300 Gs.

[0039] According to some embodiments of the present invention, the targets of the TCO-I film layer and the TCO-II film layer components are sequentially installed on each magnetron sputtering target position of a multi-target magnetron sputtering coating equipment, and then the vacuum in the magnetron sputtering cavity is pumped to less than 8×10 -4 Pa, and the TCO-I film layer and the TCO-II film layer are sequentially and continuously deposited on the substrate by magnetron sputtering to form a laminate.

[0040] In the present invention, when depositing the TCO-I film layer and the TCO-II film layer on the substrate, those skilled in the art can select to heat-treat the substrate as needed. When the substrate is not heat-treated, the deposited film layer is annealed.

[0041] According to some embodiments of the present invention, the heating temperature or the annealing temperature is 50 to 250 °C.

[0042] According to some embodiments of the present invention, the heating temperature or the annealing temperature is 100 to 200 °C.

[0043] According to the embodiments of the third aspect of the present invention, a solar cell module is provided, and the solar cell module includes the heterojunction solar cell described above.

[0044] Since the application adopts all the technical solutions of the solar cell in the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments.

[0045] Unless otherwise specified, the "about" in the present invention actually means that the allowable error is within the range of ±2%. For example, about 100 is actually 100 ± 2% × 100.

[0046] Unless otherwise specified, the "between... and..." in the present invention includes the numbers. For example, "between 2 and 3" includes the endpoint values 2 and 3.

[0047] Other features and advantages of the present invention will be described in the subsequent specification, and some of them will become obvious from the specification or be understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0049] Figure 1 is a schematic structural diagram of the heterojunction solar cell obtained in the embodiment of the present invention.

[0050] Figure 2 is a schematic structural diagram of the heterojunction solar cell obtained in Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The concept of the present invention and the technical effects produced will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts all fall within the scope of protection of the present invention.

[0052] In the description of the present invention, the description of reference terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0053] For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0054] In a common method for preparing an N-type heterojunction solar cell, the following steps are included: providing an N-type crystalline silicon substrate, cleaning and texturing the N-type crystalline silicon substrate, depositing first intrinsic hydrogenated amorphous silicon and second intrinsic hydrogenated amorphous silicon on both sides of the N-type crystalline silicon substrate by CVD respectively, depositing an N-type hydrogenated amorphous silicon layer on the outside of the first intrinsic hydrogenated amorphous silicon layer by CVD, depositing a P-type hydrogenated amorphous silicon layer on the outside of the second intrinsic hydrogenated amorphous silicon layer by CVD, depositing a first TCO layer on the outside of the N-type hydrogenated amorphous silicon layer by PVD, depositing a second TCO layer on the outside of the P-type hydrogenated amorphous silicon layer by PVD, and screen-printing Ag grid lines on the first TCO layer and the second TCO layer.

[0055] The method provided by this application is to change the second TCO layer to a stacked structure on the basis of the existing method for preparing heterojunction solar cells. The second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence. TCO-I contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:(M+N):N, where 0.0307 < M ≤ 0.1228 and 0.18 < N < 0.79. TCO-II contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:(X+Y):Y, where 0.0307 < X ≤ 0.1228 and 0 ≤ Y < 0.05. Those skilled in the art are capable of reasonably applying the method provided by this application to the preparation process of corresponding heterojunction solar cells under the guidance of this application.

[0056] The conventional manufacturing processes in the art will not be repeated. The beneficial effects of this application will be further described below in conjunction with specific examples and comparative examples.

[0057] Example 1

[0058] This example provides a heterojunction solar cell and its preparation method. For an N-type crystalline silicon substrate, the N-type crystalline silicon substrate is cleaned and textured. On both sides of the N-type crystalline silicon substrate, the first intrinsic hydrogenated amorphous silicon and the second intrinsic hydrogenated amorphous silicon are respectively deposited by CVD. On the outer side of the first intrinsic hydrogenated amorphous silicon layer, an N-type hydrogenated amorphous silicon layer is deposited by CVD. On the outer side of the second intrinsic hydrogenated amorphous silicon layer, a P-type hydrogenated amorphous silicon layer is deposited by CVD. On the outer side of the N-type hydrogenated amorphous silicon layer, a first TCO layer is deposited by PVD. On the outer side of the P-type hydrogenated amorphous silicon layer, a second TCO layer is deposited by PVD. Ag grid lines are screen-printed on the first TCO layer and the second TCO layer.

[0059] Among them, the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0060] TCO-I contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5160:0.4850.

[0061] TCO-II contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0062] The preparation method of the TCO-I film layer and the TCO-II film layer stacked in sequence specifically includes:

[0063] (1) Process the target materials of the above TCO-I and TCO-II components into target materials for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0064] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + 02) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0065] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, and the stacked structure of the TCO-I film layer and the TCO-II film layer is obtained.

[0066] The schematic diagram of the heterojunction solar cell prepared in this embodiment is as Figure 1 shown, where: 11, N-type crystalline silicon substrate; 21, first intrinsic amorphous silicon layer; 22, second intrinsic amorphous silicon layer; 31, N-type amorphous silicon layer; 32, P-type amorphous silicon layer; 41, first TCO layer; 42 second TCO layer; 51, Ag grid line; 52, Ag grid line; 421, TCO-I film layer; 422, TCO-II film layer.

[0067] Example 2

[0068] This embodiment provides a heterojunction solar cell and its preparation method. The difference between this embodiment and Example 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0069] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5465:0.4850.

[0070] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0071] The preparation method of the TCO-I film layer and the TCO-II film layer stacked in sequence specifically includes:

[0072] (1) Process the target materials of the above TCO-I and TCO-II components into target materials for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0073] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure of the vacuum chamber is about 0.7 Pa;

[0074] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, and thus obtain the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0075] Example 3

[0076] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer laminated in sequence.

[0077] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5770:0.4850.

[0078] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0079] The preparation method of the TCO-I film layer and the TCO-II film layer laminated in sequence specifically includes:

[0080] (1) Process the target materials of the above TCO-I and TCO-II components into target materials for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0081] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure of the vacuum chamber is about 0.7 Pa;

[0082] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, and thus obtain the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0083] Example 4

[0084] This example provides a heterojunction solar cell and a preparation method thereof. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and a TCO-II film layer.

[0085] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.6078:0.4850.

[0086] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0087] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0088] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0089] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0090] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, and the stacked structure of the TCO-I film layer and TCO-II film layer is obtained.

[0091] Example 5

[0092] This example provides a heterojunction solar cell and a preparation method thereof. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and a TCO-II film layer.

[0093] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.2578:0.1810.

[0094] TCO-II contains In2O3, SnO2 and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0095] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0096] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and sequentially install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment. The magnetic field intensity on the target surface is about 1000 Gs.

[0097] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), and the volume ratio O2 / (Ar + O2) = 1 - 4%. The pressure in the vacuum chamber is about 0.7 Pa;

[0098] (3) Use DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , sequentially deposit a 70-nm TCO-I film layer and a 30-nm TCO-II film layer, and then the stacked structure of the TCO-I film layer and TCO-II film layer is obtained.

[0099] Example 6

[0100] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and TCO-II film layer.

[0101] TCO-I contains In2O3, SnO2 and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.4598:0.3830.

[0102] TCO-II contains In2O3, SnO2 and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0103] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0104] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and sequentially install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment. The magnetic field intensity on the target surface is about 1000 Gs.

[0105] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + 02) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0106] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0107] Example 7

[0108] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0109] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.6638:0.5870.

[0110] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0111] The preparation method of the TCO-I film layer and the TCO-II film layer stacked in sequence specifically includes:

[0112] (1) Process the target materials of the above TCO-I and TCO-II components into target materials for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0113] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + 02) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0114] (3) Use a DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0115] Example 8

[0116] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and a TCO-II film layer.

[0117] TCO-I contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.8658:0.7890.

[0118] TCO-II contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.1018:0.0250.

[0119] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0120] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and sequentially install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment. The magnetic field strength on the target surface is about 1000 Gs.

[0121] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), and the volume ratio O2 / (Ar + O2) = 1 - 4%. The pressure in the vacuum chamber is about 0.7 Pa;

[0122] (3) Use a DC power supply for sputtering, with a sputtering power of 1.5 w / cm 2 , and sequentially deposit a 70-nm TCO-I film layer and a 30-nm TCO-II film layer to obtain the stacked structure of the TCO-I film layer and the TCO-II film layer.

[0123] Example 9

[0124] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and a TCO-II film layer.

[0125] TCO-I contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0126] TCO-II contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:0.0560:0.0250.

[0127] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0128] (1) Process the targets of the above-mentioned TCO-I and TCO-II components into targets for magnetron sputtering equipment, and sequentially install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment, with the magnetic field intensity on the target surface being about 1000 Gs.

[0129] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), with the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber being about 0.7 Pa;

[0130] (3) Use DC power supply for sputtering, with the sputtering power being 1.5 w / cm 2 , sequentially deposit a 70-nm TCO-I film layer and a 30-nm TCO-II film layer, thus obtaining the stacked structure of the TCO-I film layer and TCO-II film layer.

[0131] Example 10

[0132] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and TCO-II film layer.

[0133] TCO-I contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0134] TCO-II contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.0865:0.0250.

[0135] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0136] (1) Process the targets of the above-mentioned TCO-I and TCO-II components into targets for magnetron sputtering equipment, and sequentially install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment, with the magnetic field intensity on the target surface being about 1000 Gs.

[0137] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), with the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0138] (3) Use a DC power supply for sputtering, with a sputtering power of 1.5 W / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0139] Example 11

[0140] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that: the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer laminated in sequence.

[0141] TCO-I contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0142] TCO-II contains In2O3, SnO2, and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1170:0.0250.

[0143] The preparation method of the TCO-I film layer and the TCO-II film layer laminated in sequence specifically includes:

[0144] (1) Process the target materials of the above TCO-I and TCO-II components into target materials for a magnetron sputtering device, and install them on each magnetron sputtering target position of a multi-target magnetron sputtering coating device in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0145] (2) Place the substrate into the cavity of the magnetron sputtering coating device, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), with the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0146] (3) Use a DC power supply for sputtering, with a sputtering power of 1.5 W / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0147] Example 12

[0148] This embodiment provides a heterojunction solar cell and a preparation method thereof. The difference between this embodiment and Embodiment 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0149] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0150] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1478:0.0250.

[0151] The preparation method of the TCO-I film layer and the TCO-II film layer stacked in sequence specifically includes:

[0152] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and install them on the respective magnetron sputtering targets of a multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0153] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), and the volume ratio O2 / (Ar + O2) = 1 - 4%. The pressure in the vacuum chamber is about 0.7 Pa;

[0154] (3) Use a DC power supply for sputtering, with a sputtering power of 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, and thus obtain the laminated structure of the TCO-I film layer and the TCO-II film layer.

[0155] Embodiment 13

[0156] This embodiment provides a heterojunction solar cell and a preparation method thereof. The difference between this embodiment and Embodiment 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0157] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0158] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.0768:0.000.

[0159] The preparation method of the successively stacked TCO-I film layer and TCO-II film layer specifically includes:

[0160] (1) Process the targets of the above-mentioned TCO-I and TCO-II components into targets for magnetron sputtering equipment, and successively install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment. The magnetic field intensity on the target surface is about 1000 Gs.

[0161] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0162] (3) Use DC power supply for sputtering, the sputtering power is 1.5 w / cm 2 , successively deposit a 70-nm TCO-I film layer and a 30-nm TCO-II film layer, and the stacked structure of the TCO-I film layer and TCO-II film layer is obtained.

[0163] Example 14

[0164] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a successively stacked TCO-I film layer and TCO-II film layer.

[0165] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0166] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.0935:0.0167.

[0167] The preparation method of the successively stacked TCO-I film layer and TCO-II film layer specifically includes:

[0168] (1) Process the targets of the above-mentioned TCO-I and TCO-II components into targets for magnetron sputtering equipment, and successively install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment. The magnetic field intensity on the target surface is about 1000 Gs.

[0169] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0170] (3) Use DC power sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the stacked structure of the TCO-I film layer and the TCO-II film layer.

[0171] Example 15

[0172] This example provides a heterojunction solar cell and its preparation method. The difference between this example and Example 1 is that the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence.

[0173] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0174] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1101:0.0333.

[0175] The preparation method of the TCO-I film layer and the TCO-II film layer stacked in sequence specifically includes:

[0176] (1) Process the targets of the above TCO-I and TCO-II components into targets for magnetron sputtering equipment, and install them on each magnetron sputtering target position of the multi-target magnetron sputtering coating equipment in sequence. The magnetic field intensity on the target surface is about 1000 Gs.

[0177] (2) Place the substrate into the cavity of the magnetron sputtering coating equipment, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), the volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa;

[0178] (3) Use DC power sputtering, the sputtering power is 1.5 w / cm 2 , deposit a TCO-I film layer of 70 nm and a TCO-II film layer of 30 nm in sequence, thus obtaining the stacked structure of the TCO-I film layer and the TCO-II film layer.

[0179] Example 16

[0180] This embodiment provides a heterojunction solar cell and a preparation method thereof. The difference between this embodiment and Embodiment 1 is that the second TCO layer is composed of a sequentially stacked TCO-I film layer and a TCO-II film layer.

[0181] TCO-I contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.5618:0.4850.

[0182] TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, In:Sn:Zn = 1:0.1267:0.0499.

[0183] The preparation method of the sequentially stacked TCO-I film layer and TCO-II film layer specifically includes:

[0184] (1) Process the targets of the above TCO-I and TCO-II components into targets for a magnetron sputtering device, and sequentially install them on each magnetron sputtering target position of a multi-target magnetron sputtering coating device. The magnetic field strength on the target surface is about 1000 Gs.

[0185] (2) Place the substrate into the cavity of the magnetron sputtering coating device, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%), and the volume ratio O2 / (Ar + O2) = 1 - 4%. The pressure in the vacuum chamber is about 0.7 Pa;

[0186] (3) Use a DC power supply for sputtering. The sputtering power is 1.5 w / cm 2 , deposit a 70-nm TCO-I film layer and a 30-nm TCO-II film layer in sequence to obtain the stacked structure of the TCO-I film layer and the TCO-II film layer.

[0187] Comparative Example 1

[0188] This comparative example provides a heterojunction solar cell and a preparation method thereof. For an N-type crystalline silicon substrate, clean and texture the N-type crystalline silicon substrate, and use CVD to deposit the first intrinsic hydrogenated amorphous silicon and the second intrinsic hydrogenated amorphous silicon on both sides of the N-type crystalline silicon substrate respectively. Use CVD to deposit an N-type hydrogenated amorphous silicon layer outside the first intrinsic hydrogenated amorphous silicon layer, use CVD to deposit a P-type hydrogenated amorphous silicon layer outside the second intrinsic hydrogenated amorphous silicon layer, use PVD to deposit a first TCO layer outside the N-type hydrogenated amorphous silicon layer, use PVD to deposit a second TCO layer outside the P-type hydrogenated amorphous silicon layer, and use screen printing to print Ag grid lines on the first TCO layer and the second TCO layer.

[0189] The second TCO layer uses indium tin oxide (ITO), which contains In2O3 and SnO2. In terms of atomic molar ratio, In:Sn = 1:0.10234.

[0190] (1) Process the ITO target into a target for a magnetron sputtering device and install it on the magnetron sputtering target position of a multi-target magnetron sputtering coating device. The magnetic field intensity on the target surface is about 1000 Gs.

[0191] (2) Place the substrate into the cavity of the magnetron sputtering coating device, evacuate to a vacuum degree less than 8×10 -4 Pa, heat the substrate to 150 °C, introduce Ar gas (purity 99.99%) and oxygen (purity 99.99%). The volume ratio O2 / (Ar + O2) = 1 - 4%, and the pressure in the vacuum chamber is about 0.7 Pa.

[0192] (3) Use DC power sputtering. The sputtering power is 1.5 w / cm 2 , and deposit a 100-nm ITO film layer.

[0193] The schematic diagram of the heterojunction solar cell prepared in this comparative example is as Figure 2 shown, where: 11, N-type crystalline silicon substrate; 21, first intrinsic amorphous silicon layer; 22, second intrinsic amorphous silicon layer; 31, N-type amorphous silicon layer; 32, P-type amorphous silicon layer; 41, first TCO layer; 42, second TCO layer; 51, Ag grid line; 52, Ag grid line.

[0194] Comparative Example 2

[0195] This comparative example provides a heterojunction solar cell and its preparation method. The difference between this comparative example and Example 1 is that TCO-I contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, M is set to 0.03, N is 0.17, and In:Sn:Zn = 1:0.2:0.17, and the rest of the conditions are the same.

[0196] Comparative Example 3

[0197] This comparative example provides a heterojunction solar cell and its preparation method. The difference between this comparative example and Example 1 is that TCO-I contains In2O3, SnO2, and ZnO. In terms of atomic molar ratio, M is set to 0.13, N is 0.8, and In:Sn:Zn = 1:0.93:0.8, and the rest of the conditions are the same.

[0198] Comparative Example 4

[0199] This comparative example provides a heterojunction solar cell and a preparation method thereof. The difference between this comparative example and Example 1 is that: TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, X is set to 0.03, Y is 0.025, and according to the atomic molar ratio, In:Sn:Zn = 1:0.055:0.0250, and the other conditions are the same.

[0200] Comparative Example 5

[0201] This comparative example provides a heterojunction solar cell and a preparation method thereof. The difference between this comparative example and Example 1 is that: TCO-II contains In2O3, SnO2 and ZnO. According to the atomic molar ratio, X is set to 0.13, Y is 0.06, and according to the atomic molar ratio, In:Sn:Zn = 1:0.19:0.06, and the other conditions are the same.

[0202] Detection Example

[0203] This detection example respectively detects the performance of the heterojunction solar cell wafers prepared in Examples 1 to 16 and Comparative Example 1. The performance detection specifically includes:

[0204] (1) Photovoltaic conversion efficiency (PCE): It is a measure of the ability of a solar cell to convert light energy into electrical energy, usually expressed as a percentage.

[0205] (2) Open-circuit voltage (Voc): It is the voltage across the solar cell under no-load conditions.

[0206] (3) Short-circuit current (Isc): It is the current generated by the solar cell under short-circuit conditions.

[0207] (4) Fill factor (FF): It is the ratio of the maximum output power to the product of the open-circuit voltage and the short-circuit current.

[0208] The specific detection results of the heterojunction solar cell wafers prepared in Examples 1 to 16 and Comparative Example 1 of the present invention are shown in Table 1:

[0209] Table 1: Statistical table of specific detection of heterojunction solar cell wafers prepared in Examples 1 to 16 and Comparative Example 1 of the present invention

[0210]

[0211]

[0212] As can be seen from the data in Table 1, compared with the existing heterojunction solar cells, by changing the second TCO layer to a stacked structure, which is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence, the short-circuit current density can be significantly increased, the fill factor is slightly lower, and the open-circuit voltage has no obvious change, resulting in an increase in the photoelectric conversion efficiency of the heterojunction solar cell by about 0.2%.

[0213] In summary, for the technical solution provided in the embodiment of the present application, the heterojunction solar cell includes: an N-type crystalline silicon substrate layer, first and second intrinsic amorphous silicon layers on both sides of the N-type crystalline silicon substrate layer, an N-type amorphous silicon layer outside the first intrinsic amorphous silicon layer, a P-type amorphous silicon layer outside the second intrinsic amorphous silicon layer, a first TCO layer and an Ag grid line outside the N-type amorphous silicon layer, and a second TCO layer and an Ag grid line outside the P-type amorphous silicon layer. Among them, the second TCO layer is a stacked structure, which is composed of a TCO-I film layer and a TCO-II film layer stacked in sequence. The contact between the TCO-I film layer and the P-type amorphous silicon layer can improve the contact effect between the TCO-I and the P-type amorphous silicon layer, reduce interface recombination, and improve the carrier collection efficiency. The stacked structure of the TCO-I film layer and the TCO-II film layer has better light trapping characteristics, increases the light path length, and improves the light absorption efficiency. The contact between the TCO-II film layer and the Ag grid line can improve the contact effect between the TCO-II and the Ag grid line and improve the carrier transport efficiency. Thereby increasing the current and improving the photoelectric conversion efficiency of the battery. Under the conditions of Comparative Example 2, the contact with P silicon becomes worse, Isc decreases, and FF decreases. Under the conditions of Comparative Example 3, the contact with P silicon becomes worse, Isc decreases, and FF decreases. Under the conditions of Comparative Example 4, the contact with the Ag grid line becomes worse, Isc decreases, and FF decreases. Under the conditions of Comparative Example 5, the contact with the Ag grid line becomes worse, Isc decreases, and FF decreases.

[0214] The above has described the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art. In addition, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Claims

1. A heterojunction solar cell, characterized in that, The heterojunction solar cell includes an Ag grid line, a second TCO layer, a P-type amorphous silicon layer, a second intrinsic amorphous silicon layer, an N-type crystalline silicon substrate layer, a first intrinsic amorphous silicon layer, an N-type amorphous silicon layer, a first TCO layer, and an Ag grid line which are stacked; Wherein, the second TCO layer is composed of a TCO-I film layer and a TCO-II film layer which are stacked in sequence, The components of the TCO-I film layer include: In2O3, SnO2 and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:(M+N):N, where 0.0307 < M ≤ 0.1228 and 0.18 < N < 0.79; The components of the TCO-II film layer include: In2O3, SnO2 and ZnO. In terms of atomic molar ratio, In:Sn:Zn = 1:(X+Y):Y, where 0.0307 < X ≤ 0.1228 and 0 ≤ Y < 0.

05.

2. The heterojunction solar cell according to claim 1, wherein The thickness of the TCO-I film layer is 60 to 80 nm.

3. The heterojunction solar cell according to claim 1, wherein The thickness of the TCO-II film layer is 20 to 40 nm.

4. A method for preparing a heterojunction solar cell according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1. Deposit the first intrinsic amorphous silicon and the second intrinsic amorphous silicon on both sides of the N-type crystalline silicon substrate by CVD respectively; S2. Deposit the N-type amorphous silicon layer on the outside of the first intrinsic amorphous silicon layer by CVD, and deposit the P-type amorphous silicon layer on the outside of the second intrinsic amorphous silicon layer by CVD; S3. Deposit a first TCO layer on the outside of the N-type amorphous silicon layer, and deposit a second TCO layer on the outside of the P-type amorphous silicon layer, The deposition of the second TCO layer includes: forming a TCO-I film layer and a TCO-II film layer in sequence on the outside of the P-type amorphous silicon layer; S4. Screen-print the Ag grid line on the first TCO layer and the second TCO layer.

5. The preparation method according to claim 4, characterized in that, In step S3, the deposition method includes: at least one of physical vapor deposition and chemical vapor deposition.

6. The preparation method according to claim 5, characterized in that, The physical vapor deposition includes at least one of magnetron sputtering and evaporation deposition.

7. The preparation method according to claim 6, characterized in that, The physical vapor deposition includes magnetron sputtering; and / or, the atmosphere in the magnetron sputtering method includes: at least two of argon, hydrogen and oxygen.

8. The preparation method according to claim 7, characterized in that, The atmosphere in the magnetron sputtering method includes: argon and oxygen.

9. The preparation method according to claim 7, characterized in that, In the magnetron sputtering method, the target surface magnetic field strength is 500 Gs to 1500 Gs.

10. A solar cell module, characterized in that, The solar cell module includes the heterojunction solar cell according to any one of claims 1 to 9.

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