Solar cell and preparation method therefor, and coating device

Abstract

The present application provides a solar cell and a preparation method therefor, and a coating device. The solar cell comprises: an N-type silicon wafer; a first tin-doped indium oxide layer (104) and a second tin-doped indium oxide layer (106) which are sequentially stacked on the front side of the N-type silicon wafer; and a third tin-doped indium oxide layer (110) and a fourth tin-doped indium oxide layer (113) which are sequentially stacked on the back side of the N-type silicon wafer, wherein the mass fraction of indium oxide in the first tin-doped indium oxide layer (104) and the third tin-doped indium oxide layer (110) is greater than the mass fraction of indium oxide in the second tin-doped indium oxide layer (106) and the fourth tin-doped indium oxide layer (113).

Description

Solar cell and preparation method thereof, and coating equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 8, 2023, with application number 202311164469.4 and invention name “Solar Cells, Preparation Methods, and Coating Equipment Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the technical field of solar cells, and in particular to a solar cell and a preparation method and coating equipment thereof. Background Art

[0003] HJT (Hereto-junction with Intrinsic Thin-layer) cells are a widely used type of solar cell. Their manufacturing typically involves four major steps: texturing and cleaning, PECVD (Plasma Enhanced Chemical Vapor Deposition), PVD (Physical Vapor Deposition), and screen-printed silver electrodes. With the continuous advancement of HJT cell technology, cell efficiency has significantly increased. Continuous improvements and innovations in machinery and equipment have led to continued reductions in production costs and improved production efficiency.

[0004] In order to further reduce production costs and further improve the efficiency of solar cells, the electroplating copper process is currently commonly used to replace the screen printing silver electrode process. That is, a TCO film layer (transparent conductive film) is prepared on the amorphous silicon film through the PVD production process, a copper seed layer is PVD-plated on the TCO film layer, and then copper grid lines are electroplated on the copper seed layer to form copper electrodes. In order to make good contact between the TCO film layer and the copper electrode, the TCO film layer usually adopts an ITO film layer. The process of preparing electrodes by copper electroplating can increase the efficiency of the solar cell by 0.3% to 0.5%, and can significantly reduce the production cost compared to silver electrodes; the copper electroplating process has become a popular technology for improving efficiency and reducing costs of HJT.

[0005] However, in order to better adapt to the industrial large-scale production of HJT cells, the conversion efficiency of HJT cells using the traditional copper electroplating process still needs to be further improved. Therefore, how to better improve the conversion efficiency of HJT cells is one of the important research directions in this field.

[0006] Summary of the Invention

[0007] Based on this, it is necessary to provide a solar cell with high photoelectric conversion efficiency and its corresponding preparation method and coating equipment.

[0008] The technical solutions proposed in this application are as follows:

[0009] According to one aspect of the present application, a solar cell is provided, comprising an N-type silicon wafer and, stacked sequentially from the inside out on the front surface of the N-type silicon wafer, a first intrinsic amorphous silicon layer, an N-type doped amorphous silicon layer, a first tin-doped indium oxide (VTTO) layer, a tungsten-doped indium oxide (IWO) layer, a second tin-doped indium oxide (ITO) layer, and a first electrode;

[0010] The solar cell further comprises a second intrinsic amorphous silicon layer, a P-type doped amorphous silicon layer, a third tin-doped indium oxide (VTTO) layer, an aluminum zinc oxide (AZO) layer, a fluorine-doped tin oxide (FTO) layer, a fourth tin-doped indium oxide (ITO) layer and a second electrode, which are sequentially stacked on the back of the N-type silicon wafer from the inside to the outside;

[0011] Among them, the mass fraction of tin element in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is both less than 3%, the mass fraction of tin element in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer is both ≥3%, and the mass fraction of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is both greater than the mass fraction of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer.

[0012] In any embodiment, the mass fraction of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is greater than 97%, and the mass fraction of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer is less than or equal to 97%.

[0013] In any embodiment, the mass ratio of indium oxide to tin in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is 99:1.

[0014] In any embodiment, the thickness of the first tin-doped indium oxide layer is 30 nm to 40 nm.

[0015] In any embodiment, the thickness of the tungsten-doped indium oxide layer is 3 nm to 5 nm.

[0016] In any embodiment, the thickness of the second tin-doped indium oxide layer is 25 nm to 35 nm.

[0017] In any embodiment, the thickness of the third tin-doped indium oxide layer is 15 nm to 30 nm.

[0018] In any embodiment, the aluminum zinc oxide layer has a thickness of 30 nm to 35 nm.

[0019] In any embodiment, the thickness of the fluorine-doped tin oxide layer is 28 nm to 34 nm.

[0020] In any embodiment, the thickness of the fourth tin-doped indium oxide layer is 30 nm to 35 nm.

[0021] In any embodiment, the solar cell further includes a mixed film layer, which is located between the aluminum zinc oxide layer and the fluorine-doped tin oxide layer, and the mixed film layer contains aluminum zinc oxide and fluorine-doped tin oxide.

[0022] In any embodiment, the thickness of the mixed film layer is 2 nm to 5 nm.

[0023] In any embodiment, the first electrode and / or the second electrode is a copper electrode.

[0024] According to another aspect of the present application, a method for preparing the solar cell described above is provided, comprising the following steps:

[0025] Forming a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the front and back sides of the N-type silicon wafer, respectively;

[0026] forming an N-type doped amorphous silicon layer and a P-type doped amorphous silicon layer on the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer, respectively;

[0027] sequentially forming a first tin-doped indium oxide layer, a tungsten-doped indium oxide layer, and a second tin-doped indium oxide layer on the N-type doped amorphous layer;

[0028] sequentially forming a third tin-doped indium oxide layer, an aluminum zinc oxide layer, a fluorine-doped tin oxide layer, and a fourth tin-doped indium oxide layer on the P-type doped amorphous silicon layer; and

[0029] A first electrode and a second electrode are respectively formed on the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer.

[0030] In any embodiment, after preparing the aluminum zinc oxide layer and before preparing the fluorine-doped tin oxide layer, the preparation method further includes the step of preparing a mixed film layer containing aluminum zinc oxide and fluorine-doped tin oxide on the aluminum zinc oxide layer.

[0031] In any embodiment, the first tin-doped indium oxide layer, the tungsten-doped indium oxide layer, the second tin-doped indium oxide layer, the third tin-doped indium oxide layer, the aluminum zinc oxide layer, the fluorine-doped tin oxide layer and the fourth tin-doped indium oxide layer are prepared by physical vapor deposition.

[0032] In any embodiment, the mixed film layer is formed by physical vapor deposition by sputtering two targets simultaneously in the same deposition chamber.

[0033] In any embodiment, the first electrode and the second electrode are prepared by copper electroplating.

[0034] According to another aspect of the present application, a coating device is provided, comprising a first tin-doped indium oxide layer deposition chamber, a tungsten-doped indium oxide layer deposition chamber, a second tin-doped indium oxide layer deposition chamber, and a third tin-doped indium oxide layer deposition chamber, an aluminum zinc oxide layer deposition chamber, a fluorine-doped tin oxide layer deposition chamber, and a fourth tin-doped indium oxide layer deposition chamber, which are arranged in sequence.

[0035] In any embodiment, a mixed film layer deposition chamber is further provided between the aluminum zinc oxide layer deposition chamber and the fluorine-doped tin oxide layer deposition chamber, and at least two target positions are provided in the mixed film layer deposition chamber.

[0036] Compared with the prior art, this application has at least the following beneficial effects:

[0037] The solar cell of the present application comprises the following steps: sequentially stacking the above-mentioned first tin-doped indium oxide layer, tungsten-doped indium oxide layer, and second tin-doped indium oxide layer as the front TCO film layer between the N-type doped amorphous silicon layer on the front side of the N-type silicon wafer and the first electrode; and sequentially stacking the above-mentioned third tin-doped indium oxide layer, aluminum zinc oxide layer, fluorine-doped tin oxide layer, and fourth tin-doped indium oxide layer as the back TCO film layer between the P-type doped amorphous silicon layer on the back side of the N-type silicon wafer and the second electrode. By matching the performance of each film layer, not only can the photoelectric conversion efficiency of the solar cell be effectively improved, but the thickness of the ITO film layer in the front TCO film layer and the back TCO film layer can also be reduced, thereby reducing the amount of ITO used while ensuring good contact with the electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

[0039] FIG2 is a schematic structural diagram of a coating device according to an embodiment of the present application.

[0040] DESCRIPTION OF NUMERALS AND SIGNS: 100, solar cell; 101, N-type silicon wafer; 102, first intrinsic amorphous silicon layer; 103, N-type doped amorphous silicon layer; 104, first tin-doped indium oxide layer; 105, tungsten-doped indium oxide layer; 106, second tin-doped indium oxide layer; 107, first electrode; 108, second intrinsic amorphous silicon layer; 109, P-type doped amorphous silicon layer; 110, third tin-doped indium oxide layer; 111, aluminum zinc oxide layer; 112, fluorine-doped tin oxide layer; 113, fourth tin-doped indium oxide layer; 114, second electrode; 115, mixed film layer; 200. Coating equipment; 201. First tin-doped indium oxide layer deposition chamber; 202. Tungsten-doped indium oxide layer deposition chamber; 203. Second tin-doped indium oxide layer deposition chamber; 204. Third tin-doped indium oxide layer deposition chamber; 205. Aluminum zinc oxide layer deposition chamber; 206. Fluorine-doped tin oxide layer deposition chamber; 207. Fourth tin-doped indium oxide layer deposition chamber; 208. Mixed film layer deposition chamber; 209. Isolation chamber; 210. Pre-film transition chamber; 211. Heating chamber; 212. Post-film transition chamber. DETAILED DESCRIPTION

[0041] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0043] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] Compared to the traditional screen-printed silver electrode process, the copper electroplating process for HJT cells improves the photovoltaic conversion efficiency of cells and significantly reduces the production cost of cells. However, the photovoltaic conversion efficiency of HJT cells currently using the copper electroplating process needs to be further improved, and the production cost needs to be further reduced to better adapt to the industrial large-scale production of HJT cells.

[0046] In order to solve the above problem, referring to FIG1 , an embodiment of the present application provides a solar cell 100, which includes an N-type silicon wafer 101. On the front side of the N-type silicon wafer 101, a first intrinsic amorphous silicon layer 102, an N-type doped amorphous silicon layer 103, a first tin-doped indium oxide layer 104, a tungsten-doped indium oxide layer 105, a second tin-doped indium oxide layer 106, and a first electrode 107 are stacked in sequence from the inside to the outside; on the back side of the N-type silicon wafer 101, a second intrinsic amorphous silicon layer 108, a P-type doped amorphous silicon layer 109, and a first electrode 107 are stacked in sequence from the inside to the outside. layer 109, a third tin-doped indium oxide layer 110, an aluminum zinc oxide layer 111, a fluorine-doped tin oxide layer 112, a fourth tin-doped indium oxide layer 113 and a second electrode 114; wherein, the mass fraction of the tin element in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 is both less than 3%, the mass fraction of the tin element in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer is both ≥3%, and the mass fraction of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is both greater than the mass fraction of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer.

[0047] To ensure good contact between the TCO film and the copper electrode, an indium-based toco (ITO) film is typically used as the TCO layer in HJT cells using copper electrodes. However, the ITO film has poor light scattering and laser etching properties, is unstable in plasma environments, and the indium element in the ITO film is a rare element with limited natural reserves and a high price. Therefore, the ITO film, to a certain extent, limits the cost reduction and efficiency improvement of HJT cells.

[0048] In this regard, the present application sequentially stacks the above-mentioned first tin-doped indium oxide layer 104, tungsten-doped indium oxide layer 105 and second tin-doped indium oxide layer 106 as the front TCO film layer between the N-type doped amorphous silicon layer 103 and the first electrode 107 on the front of the N-type silicon wafer 101; wherein the first tin-doped indium oxide layer 104 can improve the bonding between the front TCO film layer and the N-type doped amorphous silicon layer 103, so that the front of the solar cell 100 has higher mobility and Voc (open circuit voltage); a tungsten-doped indium oxide layer 105 is arranged on the first tin-doped indium oxide layer 104. The tungsten-doped indium oxide has ultra-high mobility, which can increase the front TCO film. The long-wavelength transmittance coefficient of the layer and the provision of a high work function can improve the performance of the cell; the use of the second tin-doped indium oxide layer 106 as the gate line contact surface can ensure good contact between the front TCO film layer and the copper electrode; the front TCO film layer structure in which the first tin-doped indium oxide layer 104, the tungsten-doped indium oxide layer 105 and the second tin-doped indium oxide layer 106 are sequentially composited can not only improve the photoelectric conversion efficiency of the front side of the solar cell 100, but also significantly reduce the thickness of the second tin-doped indium oxide layer 106. An ultra-thin second tin-doped indium oxide layer 106 can be used, thereby reducing the use of the relatively expensive rare element indium and reducing the cost of the cell.

[0049] In addition, the present application sequentially stacks the above-mentioned third tin-doped indium oxide layer 110, aluminum zinc oxide layer 111, fluorine-doped tin oxide layer 112 and fourth tin-doped indium oxide layer 113 between the P-type doped amorphous silicon layer 109 and the second electrode 114 on the back of the N-type silicon wafer 101 as a back TCO film layer; wherein the third tin-doped indium oxide layer 110 can improve the bonding between the back TCO film layer and the P-type doped amorphous silicon layer 109; the aluminum zinc oxide layer 111 has a low resistance and its cost is much lower than that of ITO; the cost of the fluorine-doped tin oxide layer 112 is also low, and it is easy to laser etch and has suitable optical properties. The aluminum zinc oxide layer 111 and the fluorine-doped indium oxide layer 112 are used to form a TCO film layer on the back side. The tin oxide layer 112 is combined with the tin oxide layer 112 as a sandwich layer to replace ITO, reduce the thickness of the fourth tin-doped indium oxide layer 113, and reduce production costs; the fourth tin-doped indium oxide layer 113 is used as the gate line contact surface to ensure good contact between the back TCO film layer and the copper gate line electrode; the back TCO film layer structure of the third tin-doped indium oxide layer 110, the aluminum zinc oxide layer 111, the fluorine-doped tin oxide layer 112 and the fourth tin-doped indium oxide layer 113 in sequence can not only improve the photoelectric conversion efficiency of the back side of the solar cell 100, but also reduce the thickness of the fourth tin-doped indium oxide layer 113 on the back side, further reduce the use of the rare element indium, and reduce the battery cost.

[0050] The solar cell 100 of the present application utilizes a special composite film structure to form the front and back TCO film layers. This not only effectively improves the photovoltaic conversion efficiency of the solar cell 100, but also effectively reduces the thickness of the ITO film layers in the front and back TCO film layers. This ensures good contact between the copper electrode and the TCO film layers while reducing the amount of ITO used. Therefore, the solar cell 100 of the present application can further improve the photovoltaic conversion efficiency of solar cells 100 using copper electrodes and reduce the production cost of the cell.

[0051] It can be understood that the mass fraction of tin element in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 can be but not limited to 2.8%, 2.5%, 2.2%, 2.0%, 1.5%, 1.0%, and 0.5%; the mass fraction of tin element in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer can be but not limited to 3%, 3.2%, 3.5%, 3.8%, 4.0%, and 4.5%.

[0052] In some embodiments, the mass fraction of indium oxide in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 is greater than 97%, and the mass fraction of indium oxide in the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 is less than 97%. The first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 are both VTTO layers, and their indium oxide content is higher than that of the ITO layer; the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 are both ITO layers, and their indium oxide content is lower than that of the VTTO layer.

[0053] It can be understood that the mass fraction of indium oxide in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 can be but not limited to 97.5%, 98%, 98.5%, 99%, and 99.5%; the mass fraction of indium oxide in the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 can be but not limited to 97%, 96.8%, 96.5%, 96.2%, 96%, and 95.5%.

[0054] In one specific example, the mass ratio of indium oxide to tin in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110 is 99:1. That is, in the first tin-doped indium oxide layer 104 and the third tin-doped indium oxide layer 110, the mass fraction of indium oxide is 99%, and the mass fraction of tin is 1%.

[0055] In some embodiments, the thickness of the first tin-doped indium oxide layer 104 is 30nm to 40nm, the thickness of the tungsten-doped indium oxide layer 105 is 3nm to 5nm, the thickness of the second tin-doped indium oxide layer 106 is 25nm to 35nm, the thickness of the third tin-doped indium oxide layer 110 is 15nm to 30nm, the thickness of the aluminum zinc oxide layer 111 is 30nm to 35nm, the thickness of the fluorine-doped tin oxide layer 112 is 28nm to 34nm, and the thickness of the fourth tin-doped indium oxide layer 113 is 30nm to 35nm.

[0056] In some embodiments, a mixed film layer 115 containing aluminum zinc oxide and fluorine-doped tin oxide is disposed between the aluminum zinc oxide layer 111 and the fluorine-doped tin oxide layer 112 on the back surface of the solar cell 100. Disposing the mixed film layer 115 containing aluminum zinc oxide and fluorine-doped tin oxide between the aluminum zinc oxide layer 111 and the fluorine-doped tin oxide layer 112 allows for better material complementarity between the aluminum zinc oxide layer 111 and the fluorine-doped tin oxide layer 112, thereby reducing the resistivity of the film layers and increasing their mobility, further achieving an effect similar to that of ITO.

[0057] In some embodiments, the thickness of the mixed film layer 115 is 2 nm to 5 nm.

[0058] In some embodiments, the first electrode 107 and the second electrode 114 are copper electrodes. That is, the first electrode 107 is a copper electrode formed on the second tin-doped indium oxide layer through a copper electroplating process, and the second electrode 114 is a copper electrode formed on the fourth tin-doped indium oxide layer through a copper electroplating process. This application applies a front-side TCO film structure comprising a first tin-doped indium oxide layer 104, a tungsten-doped indium oxide layer 105, and a second tin-doped indium oxide layer 106, and a back-side TCO film structure comprising a third tin-doped indium oxide layer 110, an aluminum zinc oxide layer 111, a fluorine-doped tin oxide layer 112, and a fourth tin-doped indium oxide layer 113 to a solar cell 100 using copper electrodes, effectively improving the photoelectric conversion efficiency of the solar cell 100 and reducing the cell production cost.

[0059] An embodiment of the present application provides a method for preparing the solar cell 100, which includes the following steps S100 to S500:

[0060] Step S100 : forming a first intrinsic amorphous silicon layer 102 and a second intrinsic amorphous silicon layer 108 on the front and back sides of an N-type silicon wafer 101 , respectively.

[0061] In some embodiments, a first intrinsic amorphous silicon layer 102 and a second intrinsic amorphous silicon layer 108 are deposited on the front and back sides of an N-type silicon wafer 101 by PECVD (Plasma Enhanced Chemical Vapor Deposition). Prior to depositing the first intrinsic amorphous silicon layer 102 and the second intrinsic amorphous silicon layer 108, the N-type silicon wafer 101 is textured and cleaned to form a textured light-trapping structure on the front and back sides of the N-type silicon wafer 101.

[0062] Step S200 : forming an N-type doped amorphous silicon layer 103 and a P-type doped amorphous silicon layer 109 on the first intrinsic amorphous silicon layer 102 and the second intrinsic amorphous silicon layer 108 , respectively.

[0063] In some embodiments, the N-type doped amorphous silicon layer 103 and the P-type doped amorphous silicon layer 109 are deposited on the first intrinsic amorphous silicon layer 102 and the second intrinsic amorphous silicon layer 108 , respectively, by PECVD.

[0064] Step S300 : sequentially forming a first tin-doped indium oxide layer 104 , a tungsten-doped indium oxide layer 105 and a second tin-doped indium oxide layer 106 on the N-type doped amorphous layer 103 .

[0065] In some embodiments, a first tin-doped indium oxide layer 104, a tungsten-doped indium oxide layer 105, and a second tin-doped indium oxide layer 106 are sequentially deposited on the N-type doped amorphous layer 103 on the front side of the solar cell 100 using PVD, thereby forming a multi-layer composite front TCO film structure on the front side of the solar cell 100. Specifically, the first tin-doped indium oxide layer 104, the tungsten-doped indium oxide layer 105, and the second tin-doped indium oxide layer 106 are formed in separate PVD deposition chambers. The first tin-doped indium oxide layer 104 is a VTTO film layer having an indium oxide to tin ratio greater than 97:1 and an indium oxide mass fraction greater than 97%. The second tin-doped indium oxide layer 106 is an ITO film layer having an indium oxide to tin ratio less than 97:3 and an indium oxide mass fraction ≤ 97%.

[0066] In some embodiments, by controlling PVD process parameters, the thickness of the first tin-doped indium oxide layer 104 is 30 nm to 40 nm, the thickness of the tungsten-doped indium oxide layer 105 is 3 nm to 5 nm, and the thickness of the second tin-doped indium oxide layer 106 is 25 nm to 35 nm.

[0067] Step S400 : sequentially forming a third tin-doped indium oxide layer 110 , an aluminum zinc oxide layer 111 , a mixed film layer 115 containing aluminum zinc oxide and fluorine-doped tin oxide, a fluorine-doped tin oxide layer 112 and a fourth tin-doped indium oxide layer 113 on the P-type doped amorphous silicon layer 109 .

[0068] In some embodiments, PVD is used to sequentially deposit a third tin-doped indium oxide layer 110, an aluminum-zinc oxide layer 111, a mixed film layer 115 containing aluminum-zinc oxide and fluorine-doped tin oxide, a fluorine-doped tin oxide layer 112, and a fourth tin-doped indium oxide layer 113 on the P-type doped amorphous silicon layer 109 on the back side of the solar cell 100, thereby forming a multi-layer composite back-side TCO film structure on the back side of the solar cell 100. Specifically, the third tin-doped indium oxide layer 110, the aluminum-zinc oxide layer 111, the fluorine-doped tin oxide layer 112, and the fourth tin-doped indium oxide layer 113 are formed in separate PVD deposition chambers; the mixed film layer 115 containing aluminum-zinc oxide and fluorine-doped tin oxide is formed in the same PVD deposition chamber by simultaneous sputtering of two targets, one of which is an aluminum-zinc oxide target and the other is a fluorine-doped tin oxide target. Among them, the third tin-doped indium oxide layer 110 is a VTTO film layer, in which the mass ratio of indium oxide to tin is greater than 97:1, and the mass fraction of indium oxide is greater than 97%; the fourth tin-doped indium oxide layer 113 is an ITO film layer, in which the mass ratio of indium oxide to tin is less than 97:3, and the mass fraction of indium oxide is ≤97%.

[0069] In some embodiments, by controlling the PVD process parameters, the thickness of the third tin-doped indium oxide layer 110 is 15nm to 30nm, the thickness of the aluminum zinc oxide layer 111 is 30nm to 35nm, the thickness of the mixed film layer 115 is 2nm to 5nm, the thickness of the fluorine-doped tin oxide layer 112 is 28nm to 33nm, and the thickness of the fourth tin-doped indium oxide layer 113 is 30nm to 35nm.

[0070] It is understood that the first tin-doped indium oxide layer 104, the tungsten-doped indium oxide layer 105, and the second tin-doped indium oxide layer 106 can also be sequentially formed on the N-type doped amorphous layer 103, and then the third tin-doped indium oxide layer 110, the aluminum zinc oxide layer 111, the mixed film layer 115 containing aluminum zinc oxide and fluorine-doped tin oxide, the fluorine-doped tin oxide layer 112, and the fourth tin-doped indium oxide layer 113 can be sequentially formed on the P-type doped amorphous silicon layer 109. In other words, the order of step S300 and step S400 can be interchanged.

[0071] Step S500 : forming a first electrode 107 and a second electrode 114 on the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 , respectively.

[0072] In some embodiments, copper grid lines are formed on the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 by copper electroplating to form the first electrode 107 and the second electrode 114. The first electrode 107 and the second electrode 114 are both copper electrodes.

[0073] In one specific example, a copper seed layer is first formed on the second tin-doped indium oxide layer 106 and the fourth tin-doped indium oxide layer 113 respectively through a PVD process; then a photosensitive resin layer is formed on the copper seed layer, and the photosensitive resin layer is patterned exposed and developed to form a patterned groove on the photosensitive resin layer, and the copper seed layer in the patterned groove is exposed; then a copper electrode is formed by electroplating on the copper seed layer in the patterned groove through a copper electroplating process; and then the remaining photosensitive resin layer and the copper seed layer outside the area where the copper electrode is located are removed.

[0074] Referring to FIG. 2 , one embodiment of the present application provides a coating apparatus 200 for depositing the TCO film layer in the solar cell 100 of the present application. The coating apparatus 200 includes a first tin-doped indium oxide layer deposition chamber 201, a tungsten-doped indium oxide layer deposition chamber 202, a second tin-doped indium oxide layer deposition chamber 203, a third tin-doped indium oxide layer deposition chamber 204, an aluminum zinc oxide layer deposition chamber 205, a fluorine-doped tin oxide layer deposition chamber 206, and a fourth tin-doped indium oxide layer deposition chamber 207. In FIG. 2 , RP represents a mechanical pump, SP represents a roots pump, TP represents a molecular pump, and RGA represents an RGA water vapor monitor.

[0075] Among them, a VTTO target is provided in the first tin-doped indium oxide layer deposition chamber 201 for depositing a first tin-doped indium oxide layer 104 on the N-type doped amorphous layer 103 on the front of the solar cell 100; a tungsten-doped indium oxide target is provided in the tungsten-doped indium oxide layer deposition chamber 202 for depositing a tungsten-doped indium oxide layer 105 on the first tin-doped indium oxide layer 104; a tin-doped indium oxide (ITO) target is provided in the second tin-doped indium oxide layer deposition chamber 203 for depositing a second tin-doped indium oxide layer 106 on the tungsten-doped indium oxide layer 105; a VTT target is provided in the third tin-doped indium oxide layer deposition chamber 204 O target material is used to deposit a third tin-doped indium oxide layer 110 on the P-type doped amorphous layer 109 on the back of the solar cell 100; an aluminum zinc oxide target material is provided in the aluminum zinc oxide layer deposition chamber 205, which is used to deposit an aluminum zinc oxide layer 111 on the third tin-doped indium oxide layer 110; a fluorine-doped tin oxide target material is provided in the fluorine-doped tin oxide layer deposition chamber 206, which is used to deposit a fluorine-doped tin oxide layer 112 on the aluminum zinc oxide layer 111; a tin-doped indium oxide (ITO) target material is provided in the fourth tin-doped indium oxide layer deposition chamber 207, which is used to deposit a fourth tin-doped indium oxide layer 113 on the fluorine-doped tin oxide layer 112.

[0076] In some embodiments, a mixed film layer deposition chamber 208 is further provided between the aluminum zinc oxide layer deposition chamber 205 and the fluorine-doped tin oxide layer deposition chamber 206. The mixed film layer deposition chamber 208 is provided with at least two target positions. One target position is used to place an aluminum zinc oxide target, and the other target position is used to place a fluorine-doped tin oxide target. Through simultaneous sputtering at the two target positions, a mixed film layer 115 containing aluminum zinc oxide and fluorine-doped tin oxide is formed on the aluminum zinc oxide layer 111.

[0077] In some embodiments, an isolation chamber 209 is further provided between the second tin-doped indium oxide layer deposition chamber 203 and the third tin-doped indium oxide layer deposition chamber 204 to isolate the deposition chamber of the front TCO film layer from the deposition chamber of the back TCO film layer to improve the coating quality.

[0078] In some embodiments, a plurality of pre-film transition chambers 210 and heating chambers 211 are further provided at the front end of the first tin-doped indium oxide layer deposition chamber 201 ; a plurality of post-film transition chambers 212 are further provided at the rear end of the fourth tin-doped indium oxide layer deposition chamber 207 .

[0079] By using the above-mentioned coating equipment 200 of the present application, a first tin-doped indium oxide layer 104, a tungsten-doped indium oxide layer 105 and a second tin-doped indium oxide layer 106 can be deposited in sequence on the front side of the solar cell 100, and a third tin-doped indium oxide layer 110, an aluminum zinc oxide layer 111, a mixed film layer 115, a fluorine-doped tin oxide layer 112 and a fourth tin-doped indium oxide layer 113 can be deposited in sequence on the back side of the solar cell 100, thereby forming the front TCO film layer structure and the back TCO film layer structure in the solar cell 100 of the present application.

[0080] The present application will be further described below with reference to specific embodiments and comparative examples, but they should not be construed as limiting the scope of protection of the present application.

[0081] Example 1:

[0082] An HJT battery comprises an N-type silicon wafer, on the front side of which are stacked, from the inside out, a first intrinsic amorphous silicon layer, an N-type doped amorphous silicon layer, a first tin-doped indium oxide (VTTO) layer with a thickness of 34.5 nm, a tungsten-doped indium oxide layer with a thickness of 3.5 nm, a second tin-doped indium oxide (ITO) layer with a thickness of 28.5 nm, and a first copper electrode; and on the back side of the N-type silicon wafer, a second intrinsic amorphous silicon layer, a P-type doped amorphous silicon layer, a third tin-doped indium oxide (VTTO) layer with a thickness of 28.5 nm, an aluminum zinc oxide layer with a thickness of 30.5 nm, a mixed film layer of aluminum zinc oxide and fluorine-doped tin oxide with a thickness of 3.5 nm, a fluorine-doped tin oxide layer with a thickness of 34 nm, a fourth tin-doped indium oxide (ITO) layer with a thickness of 30.5 nm, and a second copper electrode.

[0083] The first intrinsic amorphous silicon layer, the N-type doped amorphous silicon layer, the second intrinsic amorphous silicon layer, and the P-type doped amorphous silicon layer were fabricated using PECVD. The first tin-doped indium oxide layer, the tungsten-doped indium oxide layer, the second tin-doped indium oxide layer, the third tin-doped indium oxide layer, the aluminum-zinc oxide layer, the mixed film layer, the fluorine-doped tin oxide layer, and the fourth tin-doped indium oxide layer were fabricated using PVD. The first and second copper electrodes were fabricated using copper electroplating. The indium oxide mass fraction in the first and third tin-doped indium oxide layers was 99%, with an indium oxide to tin mass ratio of 99:1. The indium oxide mass fraction in the second and fourth tin-doped indium oxide layers was 97%, with an indium oxide to tin mass ratio of 97:3.

[0084] After the HJT cells were assembled into a module, the module performance was tested; the performance of the HJT cell was inferred from the module's CTM100% conversion ratio. The test showed that the photoelectric conversion efficiency of the HJT cell in this embodiment was approximately 25.10%.

[0085] Example 2:

[0086] An HJT cell comprises an N-type silicon wafer, wherein a first intrinsic amorphous silicon layer, an N-type doped amorphous silicon layer, a first tin-doped indium oxide (VTTO) layer with a thickness of 30.5 nm, a tungsten-doped indium oxide layer with a thickness of 3.5 nm, a second tin-doped indium oxide (ITO) layer with a thickness of 25.5 nm, and a first copper electrode are sequentially stacked on the front side of the N-type silicon wafer from the inside out; and a second intrinsic amorphous silicon layer, a P-type doped amorphous silicon layer, a third tin-doped indium oxide (VTTO) layer with a thickness of 20.5 nm, an aluminum zinc oxide layer with a thickness of 30.5 nm, a mixed film of aluminum zinc oxide and fluorine-doped tin oxide with a thickness of 3.5 nm, a fluorine-doped tin oxide layer with a thickness of 30.5 nm, a fourth tin-doped indium oxide (ITO) layer with a thickness of 33.5 nm, and a second copper electrode are sequentially stacked on the back side of the N-type silicon wafer from the inside out. The preparation methods and equipment used for each film layer and electrode are the same as those in Example 1. The mass fraction of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is 99%, and the mass ratio of indium oxide to tin is 99:1; the mass fraction of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer is 97%, and the mass ratio of indium oxide to tin is 97:3.

[0087] After assembling the HJT cells into a module, the module performance was tested; the performance of the HJT cell was inferred from the module's CTM100% conversion ratio. The test showed that the photoelectric conversion efficiency of the HJT cell in this embodiment was approximately 26.05%.

[0088] Comparative Example 1:

[0089] A HJT battery, the structure of which is basically the same as that of Example 1, except that: the front side of the N-type silicon wafer is not provided with a first tin-doped indium oxide (VTTO) layer and a tungsten-doped indium oxide layer, but is provided with a single tin-doped indium oxide (ITO) film layer, and the thickness of the tin-doped indium oxide (ITO) film layer is equal to the sum of the thicknesses of the first tin-doped indium oxide (VTTO) layer, the tungsten-doped indium oxide layer, and the second tin-doped indium oxide (ITO) layer in Example 1; the back side of the N-type silicon wafer is not provided with a third tin-doped indium oxide (VTTO) layer, an aluminum-zinc oxide layer, a mixed film layer, and a fluorine-doped tin oxide layer, but is provided with a single tin-doped indium oxide (ITO) film layer, and the thickness of the tin-doped indium oxide (ITO) film layer is equal to the sum of the thicknesses of the third tin-doped indium oxide (VTTO) layer, the aluminum-zinc oxide layer, the mixed film layer, the fluorine-doped tin oxide layer, and the fourth tin-doped indium oxide (ITO) layer in Example 1.

[0090] After assembling the HJT cells into a module, the module performance was tested; the performance of the HJT cell was inferred from the module's CTM100% conversion ratio. The test showed that the photoelectric conversion efficiency of the HJT cell in this embodiment was approximately 24.40%.

[0091] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-described embodiments merely represent several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make a number of variations and improvements without departing from the concept of the present application, and these variations and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the appended claims, and the description and drawings may be used to interpret the content of the claims.

Claims

1. A solar cell, comprising an N-type silicon wafer and a first intrinsic amorphous silicon layer, an N-type doped amorphous silicon layer, a first tin-doped indium oxide layer, a tungsten-doped indium oxide layer, a second tin-doped indium oxide layer and a first electrode stacked in sequence from inside to outside on the front side of the N-type silicon wafer; The solar cell also includes a second intrinsic amorphous silicon layer, a P-type doped amorphous silicon layer, a third tin-doped indium oxide layer, an aluminum zinc oxide layer, a fluorine-doped tin oxide layer, a fourth tin-doped indium oxide layer and a second electrode, which are sequentially stacked from the inside to the outside on the back of the N-type silicon wafer; in, The mass fractions of tin in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer are both less than 3%, the mass fractions of tin in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer are both ≥3%, and the mass fractions of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer are both greater than the mass fractions of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer.

2. The solar cell according to claim 1, wherein: The mass fractions of indium oxide in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer are both greater than 97%, and the mass fractions of indium oxide in the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer are both less than or equal to 97%.

3. The solar cell according to any one of claims 1 to 2, wherein: The mass ratio of indium oxide to tin element in the first tin-doped indium oxide layer and the third tin-doped indium oxide layer is 99:

1.

4. The solar cell according to any one of claims 1 to 3, wherein: The thickness of the first tin-doped indium oxide layer is 30 nm to 40 nm.

5. The solar cell according to any one of claims 1 to 4, wherein: The thickness of the tungsten-doped indium oxide layer is 3nm-5nm.

6. The solar cell according to any one of claims 1 to 5, wherein: The thickness of the second tin-doped indium oxide layer is 25 nm to 35 nm.

7. The solar cell according to any one of claims 1 to 6, wherein: The thickness of the third tin-doped indium oxide layer is 15 nm to 30 nm.

8. The solar cell according to any one of claims 1 to 7, wherein: The thickness of the aluminum zinc oxide layer is 30nm-35nm.

9. The solar cell according to any one of claims 1 to 8, wherein: The thickness of the fluorine-doped tin oxide layer is 28nm-34nm.

10. The solar cell according to any one of claims 1 to 9, wherein: The thickness of the fourth tin-doped indium oxide layer is 30 nm to 35 nm.

11. The solar cell according to any one of claims 1 to 10, wherein: The solar cell further comprises a mixed film layer, which is located between the aluminum zinc oxide layer and the fluorine-doped tin oxide layer, and contains aluminum zinc oxide and fluorine-doped tin oxide.

12. The solar cell according to claim 11, wherein: The thickness of the mixed film layer is 2nm-5nm.

13. The solar cell according to any one of claims 1 to 12, wherein: The first electrode and / or the second electrode is a copper electrode.

14. A method for preparing a solar cell according to any one of claims 1 to 13, wherein: The steps include: Prepare a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the front and back sides of the N-type silicon wafer respectively; Preparing an N-type doped amorphous silicon layer and a P-type doped amorphous silicon layer on the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer, respectively; sequentially preparing a first tin-doped indium oxide layer, a tungsten-doped indium oxide layer, and a second tin-doped indium oxide layer on the N-type doped amorphous layer; sequentially preparing a third tin-doped indium oxide layer, an aluminum zinc oxide layer, a fluorine-doped tin oxide layer and a fourth tin-doped indium oxide layer on the P-type doped amorphous silicon layer; as well as A first electrode and a second electrode are respectively prepared on the second tin-doped indium oxide layer and the fourth tin-doped indium oxide layer.

15. The method for preparing a solar cell according to claim 14, wherein: After preparing the aluminum zinc oxide layer and before preparing the fluorine-doped tin oxide layer, the preparation method further comprises the step of preparing a mixed film layer containing aluminum zinc oxide and fluorine-doped tin oxide on the aluminum zinc oxide layer.

16. The method for preparing a solar cell according to claim 15, wherein: The first tin-doped indium oxide layer, the tungsten-doped indium oxide layer, the second tin-doped indium oxide layer, the third tin-doped indium oxide layer, the aluminum zinc oxide layer, the fluorine-doped tin oxide layer and the fourth tin-doped indium oxide layer are prepared by physical vapor deposition.

17. The method for preparing a solar cell according to any one of claims 15 to 16, wherein: The mixed film layer is prepared by simultaneously sputtering double targets in the same deposition chamber through physical vapor deposition.

18. The method for preparing a solar cell according to any one of claims 15 to 17, wherein: The first electrode and the second electrode are prepared by copper electroplating.

19. A coating device, comprising a first tin-doped indium oxide layer deposition chamber, a tungsten-doped indium oxide layer deposition chamber, a second tin-doped indium oxide layer deposition chamber, and a third tin-doped indium oxide layer deposition chamber, an aluminum zinc oxide layer deposition chamber, a fluorine-doped tin oxide layer deposition chamber, and a fourth tin-doped indium oxide layer deposition chamber arranged in sequence.

20. The coating device according to claim 19, wherein: A mixed film layer deposition chamber is further provided between the aluminum zinc oxide layer deposition chamber and the fluorine-doped tin oxide layer deposition chamber, and at least two target positions are provided in the mixed film layer deposition chamber.

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