Photovoltaic heterojunction cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a photovoltaic heterojunction cell and a preparation method thereof. The invention provides a photovoltaic heterojunction cell in the first aspect, which comprises a power generation device, and the power generation device comprises a first surface and a second surface which are oppositely arranged; a first conductive functional layer is arranged on the first surface, and a second conductive functional layer is arranged on the second surface; a first electrode and a first anti-reflection layer are arranged on one side, far away from the first surface, of the first conductive functional layer; a second electrode and a second anti-reflection layer are arranged on the side, away from the second surface, of the second conductive function layer. According to the photovoltaic heterojunction cell, the TCO in the photovoltaic heterojunction cell is divided into the two functional layers, namely the conductive functional layer and the anti-reflection layer, meanwhile, the electrode is in direct contact with the conductive functional layer, the anti-reflection layer does not contain indium, and therefore dependence on the rare element indium is reduced. On the premise that the performance of the photovoltaic heterojunction cell is maintained or even improved, the production cost of the photovoltaic heterojunction cell is greatly reduced.

Description

Technical Field

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

[0002] The manufacturing process of photovoltaic heterojunction cells (HJT cells) consists of texturing, amorphous silicon / doped microcrystalline silicon, TCO (transparent conductive oxide) deposition, and metallization. ITO (doped indium oxide) is usually deposited because ITO has both conductive and anti-reflective functions. However, ITO film contains rare metal indium, which makes it expensive and is not conducive to the industrialization of HJT cells.

[0003] At present, cost reduction is usually achieved by using indium-free or low-indium methods. For example, ITO films are replaced by AZO (aluminum-doped zinc oxide), GAZO (aluminum-gallium co-doped zinc oxide), SnO2 and other films. However, the electrical and / or optical properties of the above films will decline to a certain extent.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0005] The embodiments of the present application provide a photovoltaic heterojunction cell and a method for preparing the same, so as to alleviate the dependence of the HJT cell on the indium element.

[0006] In a first aspect, an embodiment of the present application provides a photovoltaic heterojunction cell, including a power generation device, wherein the power generation device includes a first surface and a second surface arranged opposite to each other; A first conductive functional layer is disposed on the first surface, and a second conductive functional layer is disposed on the second surface; A first electrode and a first anti-reflection layer are provided on a side of the first conductive functional layer away from the first surface; A second electrode and a second anti-reflection layer are disposed on a side of the second conductive functional layer away from the second surface.

[0007] In the first aspect of the embodiment of the present application, the TCO in the photovoltaic heterojunction cell is split into two functional layers - a conductive functional layer and an anti-reflection layer, and the electrode is directly in contact with the conductive functional layer. The anti-reflection layer does not contain indium, thereby reducing the dependence on the rare element indium. In the first aspect of the embodiment of the present application, the cost of the TCO film is greatly reduced while ensuring that the photoelectric performance of the two functional layers is equal to or even better than the original TCO, thereby greatly reducing the production cost of the photovoltaic heterojunction cell while maintaining or even improving the performance of the photovoltaic heterojunction cell.

[0008] A second aspect of the embodiments of the present application provides a method for preparing a photovoltaic heterojunction cell, comprising the following operations: providing a power generation device; Depositing a first conductive functional layer on the front side of the power generation device, preparing a first electrode on the first conductive functional layer, depositing a first anti-reflection layer on the side of the first conductive functional layer and the first electrode away from the power generation device, and then performing a film opening treatment at the position of the first electrode to expose the first electrode; A second conductive functional layer is deposited on the back side of the power generation device, a second electrode is prepared on the second conductive functional layer, a second anti-reflection layer is deposited on the side of the second conductive functional layer and the second electrode away from the power generation device, and then a film opening treatment is performed at the position of the second electrode to expose the second electrode.

[0009] Thus, a photovoltaic heterojunction cell is obtained.

[0010] A second aspect of the embodiment of the present application further provides a method for preparing a photovoltaic heterojunction cell, comprising the following operations: providing a power generation device; Depositing a first conductive functional layer on the front side of the power generation device; Depositing a second conductive functional layer on the back side of the power generation device; preparing a first electrode on the first conductive functional layer; preparing a second electrode on the second conductive functional layer; Covering the first conductive functional layer and the second conductive functional layer with photosensitive adhesive films respectively; performing exposure and development to expose the non-electrode area; After exposure, a first anti-reflection layer is deposited on a side of the photosensitive adhesive film away from the first conductive functional layer; After exposure, a second anti-reflection layer is deposited on a side of the photosensitive adhesive film away from the second conductive functional layer; The photosensitive adhesive film is removed to expose the first electrode and the second electrode.

[0011] Thus, a photovoltaic heterojunction cell is obtained, and device damage caused by laser film opening can be avoided during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0013] Figure 1 is a schematic structural diagram of a photovoltaic heterojunction cell provided in an embodiment of the present application; Figure 2 is a schematic diagram of the structure of a power generation device provided in an embodiment of the present application; Figure 3This is a schematic diagram of a structure in which a photosensitive adhesive film is covered on the surface of a power generation device provided in an embodiment of the present application; Figure 4 It is a schematic diagram of the structure of exposing and developing a photosensitive adhesive film covering the surface of a power generation device provided in an embodiment of the present application; Figure 5 It is a schematic diagram of the structure after backwashing and membrane removal provided in an embodiment of the present application.

[0014] Description of reference numerals: 1-power generation device; 2-first conductive functional layer; 3-first electrode; 4-first anti-reflection layer; 1-1-N-type silicon substrate; 5-second conductive functional layer; 6-second electrode; 7-second anti-reflection layer; 8-photosensitive adhesive film; 1-2-first intrinsic amorphous silicon; 1-3-N-type silicon layer; 1-4-second intrinsic amorphous silicon; 1-5-P-type silicon layer. DETAILED DESCRIPTION

[0015] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0016] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not mean that the present disclosure necessarily has the first element, component, region, layer or part.

[0017] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0019] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0020] The following provides an explanation of the terms used in this application.

[0021] TCO: transparent conductive oxide; PECVD: plasma enhanced chemical vapor deposition; PVD: physical vapor deposition; HJT: Photovoltaic heterojunction cell; ITO: doped indium oxide; IMO: transition metal doped indium oxide, where M is Ti, Zr, Ta, Sn, etc.; In2O3: Sn: tin-doped indium oxide; AZO: aluminum-doped zinc oxide; GAZO: aluminum-gallium co-doped zinc oxide; SnO2: Tin oxide.

[0022] The embodiments of the present application provide a photovoltaic heterojunction cell and a method for preparing the same, as described below.

[0023] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0024] like Figure 1 As shown, the first aspect of the embodiment of the present application provides a photovoltaic heterojunction cell. The photovoltaic heterojunction cell includes a power generation device 1, and the power generation device 1 includes a first surface and a second surface arranged opposite to each other; A first conductive functional layer 2 is provided on the first surface, and a second conductive functional layer 5 is provided on the second surface; A first electrode 3 and a first anti-reflection layer 4 are provided on a side of the first conductive functional layer 2 away from the first surface; A second electrode 6 and a second anti-reflection layer 7 are disposed on a side of the second conductive functional layer 5 away from the second surface.

[0025] In the first aspect of the embodiment of the present application, the TCO in the photovoltaic heterojunction cell is split into two functional layers - a conductive functional layer and an anti-reflection layer, and the electrode is directly in contact with the conductive functional layer, and the anti-reflection layer does not contain indium, thereby reducing the dependence on the rare element indium. In the first aspect of the embodiment of the present application, the growth cost of the TCO film is greatly reduced while ensuring that the photoelectric performance of the two functional layers is equal to or even better than the original TCO, thereby greatly reducing the production cost of the photovoltaic heterojunction cell while maintaining or even improving the performance of the photovoltaic heterojunction cell.

[0026] In some embodiments, in a photovoltaic heterojunction cell, see Figure 2 The power generation device 1 includes an N-type silicon substrate 1-1, a first intrinsic amorphous silicon 1-2 and an N-type silicon layer 1-3 (such as an N-type microcrystalline silicon layer) are sequentially arranged on the front side of the N-type silicon substrate 1-1; a second intrinsic amorphous silicon 1-4 and a P microcrystalline silicon layer 1-5 are sequentially arranged on the back side of the N-type silicon substrate 1-1. Thus, a power generation device is formed.

[0027] Further, the thickness of the N-type silicon substrate is 110 μm to 150 μm, for example, 110 μm, 120 μm, 135 μm, 150 μm, etc.; the thickness of the first intrinsic amorphous silicon is 4 nm to 7 nm, for example, 4 nm, 5 nm, 6 nm, 7 nm, etc.; the thickness of the N-type silicon layer is 20 nm to 25 nm, for example, 20 nm, 22 nm, 23 nm, 25 nm, etc.; the thickness of the second intrinsic amorphous silicon is 4 nm to 7 nm, for example, 4 nm, 5 nm, 6 nm, 7 nm, etc.; the thickness of the P-type silicon layer is 25 nm to 30 nm, for example, 25 nm, 27 nm, 28 nm, 30 nm, etc. Thus, the performance of the power generation device 1 is better.

[0028] In some embodiments, in the photovoltaic heterojunction cell, the optimal anti-reflection wavelength of the first conductive functional layer 2 and the first anti-reflection layer 4 is 512nm to 662nm, for example, 512nm, 532nm, 542nm, 582nm, 622nm, 662nm, etc. As a result, the optimal absorption light of the first conductive functional layer 2 and the first anti-reflection layer 4 as a whole is red-shifted, and most of it is still in the visible light range, so that the overall anti-reflection effect of the first conductive functional layer 2 and the first anti-reflection layer 4 is equivalent to or even better than that of the original TCO, and the first conductive functional layer 2 and the first anti-reflection layer 4 have the best absorbance near the optimal anti-reflection wavelength.

[0029] It is worth noting that the optimal anti-reflection wavelength of the first conductive functional layer 2 and the first anti-reflection layer 4 is the optimal anti-reflection wavelength of the first conductive functional layer 2 and the first anti-reflection layer 4 as a whole, which is calculated based on the thin film interference principle using the refractive index and thickness of the film. The original ITO film before improvement has a refractive index of 2.0 and a thickness of 45nm to 52nm, and the corresponding optimal anti-reflection wavelength is 400nm to 420nm. The embodiment of the present application broadens the optimal anti-reflection wavelength and has better light absorption rate.

[0030] In some embodiments, in the photovoltaic heterojunction cell, the optimal anti-reflection wavelength of the second conductive functional layer 5 and the second anti-reflection layer 7 is 512nm to 662nm, for example, 512nm, 532nm, 542nm, 582nm, 622nm, 662nm, etc.

[0031] In some embodiments, in the photovoltaic heterojunction cell, the carrier mobility of the first conductive functional layer 2 and the second conductive functional layer 5 are independently 60 cm 2 / V·s~80cm 2 / V·s, for example, 60cm 2 / V·s、70cm 2 / V·s、75cm 2 / V·s, 80cm2 / V·s, etc., but are not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. Therefore, the conductive functional layer can ensure the conductivity and lateral transmission ability of the film. In the embodiment of the present application, the carrier mobility of the two conductive functional layers is further calculated by measuring the Hall effect using the Van der Pauw method to obtain the carrier mobility.

[0032] As an optional technical solution of the present application, the first conductive functional layer 2 located on the front side includes one or more of tin-doped indium oxide (In2O3: Sn) and transition metal-doped indium oxide IMO. Among them, M is at least one of Ti, Zr, Ta, Sn, etc. Therefore, on the premise of having conductivity, it also has high transmittance to infrared light.

[0033] Further, the thickness of the first conductive functional layer 2 is 10 nm to 20 nm, for example, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc., but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. Therefore, the first conductive functional layer 2 with a smaller thickness is used, so that its mobility and carrier concentration are increased to a certain extent, which is beneficial to the conductive performance. The selection principle of the material and thickness of the second conductive functional layer 5 is the same as that of the first conductive functional layer 2, and will not be repeated here.

[0034] Furthermore, the refractive index of the first conductive functional layer 2 is 1.9-2.1, so that the optimal anti-reflection wavelength of the first conductive functional layer 2 and the first anti-reflection layer 4 as a whole is 512nm-662nm.

[0035] In some embodiments, in the photovoltaic heterojunction cell, the refractive index of the first anti-reflection layer 4 is 2.0 to 3, for example, 2.0, 2.3, 2.5, 2.8, 3.0, etc., but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. Thus, it is beneficial to the anti-reflection effect. In the embodiment of the present application, the refractive index of the anti-reflection layer 4 is obtained by full-spectrum ellipsometer testing.

[0036] Specifically, the first anti-reflection layer 4 can be made of a material commonly used as an anti-reflection film in other solar cells, for example, SiN x 、AlO a 、SiO b N c, SiO2, etc. Furthermore, the first anti-reflection layer 4 may be a single-layer structure or a laminated structure. When the first anti-reflection layer 4 is a laminated structure, the refractive index of each laminate of the first anti-reflection layer 4 decreases from the direction close to the conductive functional layer 2 to the direction away from the first conductive functional layer 2. The first anti-reflection layer 4 may be composed of one material with different refractive indices, or may be composed of two or more materials with different refractive indices. Thus, the first anti-reflection layer 4 may have a better optical response in a wider wavelength range. In addition, the anti-reflection layer using a laminated structure can increase the refractive index on the side close to the conductive functional layer, which means that the hydrogen content on the side of the anti-reflection layer close to the conductive functional layer can be increased, which is beneficial to the subsequent hydrogen passivation to reduce defects.

[0037] In some embodiments, in a direction from close to the first conductive functional layer to away from the first conductive functional layer, the first anti-reflection layer includes a first stack, a second stack and a third stack; wherein the thickness of the first stack is 10 nm to 15 nm, the thickness of the second stack is 10 nm to 15 nm, and the thickness of the third stack is 15 nm to 25 nm; the refractive index of the first stack is 3.0 to 2.8, the refractive index of the second stack is 2.8 to 2.5, and the refractive index of the second stack is 2.5 to 2.0.

[0038] As some examples, the thickness of the first stack can be 10 nm, 12 nm, 15 nm, etc., the thickness of the second stack can be 10 nm, 12 nm, 15 nm, etc., and the thickness of the third stack can be 15 nm, 20 nm, 25 nm, etc. As some other examples, the refractive index of the first stack can be 3.0, 2.9, 2.8, etc., the refractive index of the second stack can be 2.8, 2.6, 2.5, etc., and the refractive index of the third stack can be 2.5, 2.2, 2.0, etc.

[0039] For example, the first anti-reflection layer 4 is a stacked structure, including SiN with refractive indexes of 2.8, 2.5, and 2.0 from the inside to the outside, and thicknesses of 10 nm, 15 nm, and 25 nm. x In addition, by adjusting the refractive index range of the first anti-reflection layer 4 on the N-side (the front side of the power generation device), the first anti-reflection layer 4 can be enriched with a large amount of fixed negative charges, thereby enhancing the field passivation effect of the N-side and further improving the device performance.

[0040] As an optional technical solution of the present application, the first anti-reflection layer 4 can be prepared by plasma enhanced chemical deposition (PECVD), which contains a large amount of hydrogen, providing a large amount of hydrogen source for subsequent light injection and electrical injection processing devices, facilitating hydrogen passivation.

[0041] The configuration of the second anti-reflection layer 7 refers to the first anti-reflection layer 4 and will not be described in detail here.

[0042] In some embodiments, in the photovoltaic heterojunction cell, the sum of the thicknesses of the first conductive functional layer 2 and the first anti-reflection layer 4 is 50 nm to 65 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, etc. Thus, the overall anti-reflection effect of the first conductive functional layer 2 and the first anti-reflection layer 4 is optimized.

[0043] In some embodiments, in the photovoltaic heterojunction cell, the sum of the thicknesses of the second conductive functional layer 5 and the second anti-reflection layer 7 is 50 nm to 65 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, etc. Thus, the anti-reflection effect of the second conductive functional layer 5 and the second anti-reflection layer 7 is optimized.

[0044] A second aspect of the embodiments of the present application provides a method for preparing a photovoltaic heterojunction cell.

[0045] In some embodiments, laser film opening is used to prepare photovoltaic heterojunction cells, which specifically includes the following operations: providing a power generation device 1; Depositing a first conductive functional layer 2 on the front side of the power generation device 1, preparing a first electrode 3 on the first conductive functional layer 2, depositing a first anti-reflection layer 4 on the side of the first conductive functional layer 2 and the first electrode 3 away from the power generation device 1, and then performing a film opening treatment at the position of the first electrode 3 to expose the first electrode 3; A second conductive functional layer 5 is deposited on the back of the power generation device 1, a second electrode 6 is prepared on the second conductive functional layer 5, a second anti-reflection layer 7 is deposited on the side of the second conductive functional layer 5 and the second electrode 6 away from the power generation device, and then a film opening treatment is performed at the position of the second electrode 6 to expose the second electrode 6. Thus, a photovoltaic heterojunction cell is obtained.

[0046] In some other embodiments, see Figure 3 to Figure 5 , a photovoltaic heterojunction cell is prepared by a mask method, specifically comprising the following operations: providing a power generation device 1; depositing a first conductive functional layer 2 on the front side of the power generation device 1; depositing a second conductive functional layer 5 on the back side of the power generation device 1; preparing a first electrode 3 on the first conductive functional layer 2 on the front side; preparing a second electrode 6 on the second conductive functional layer 5 on the back side; covering the first conductive functional layer 2 and the second conductive functional layer 5 with a photosensitive adhesive film 8, respectively, at this time, see Figure 3; performing exposure and development to expose the second electrode 6 in the non-electrode area (the area except the area where the first electrode 3 and the second electrode 6 are located); after exposure, depositing the first anti-reflection layer 4 on the side of the photosensitive adhesive film away from the first conductive functional layer 2; after exposure, depositing the second anti-reflection layer 7 on the side of the photosensitive adhesive film away from the second conductive functional layer 5, see Figure 4 ; Backwashing to remove the photosensitive adhesive film to expose the first electrode 3 and the second electrode 6, see Figure 5 Thus, a photovoltaic heterojunction cell is obtained, and device damage caused by laser film opening can be avoided during the preparation process.

[0047] In some embodiments, in the method for preparing a photovoltaic heterojunction cell, see Figure 2 The power generation device 1 includes a textured N-type silicon substrate 1-1, wherein a first intrinsic amorphous silicon 1-2 and an N-type silicon layer 1-3 are sequentially arranged on the front side of the N-type silicon substrate 1-1; and a second intrinsic amorphous silicon 1-4 and a P-type silicon layer 1-5 are sequentially arranged on the back side of the N-type silicon substrate 1-1. The N-type silicon layer 1-3 may be an N-type microcrystalline silicon layer, and the P-type silicon layer 1-5 may be a P-type microcrystalline silicon layer.

[0048] The following will conduct performance tests on the structure or manufacturing method of the photovoltaic heterojunction cell provided in the embodiments of the present application and related comparative examples.

[0049] [Example 1] Step 1: providing a 120 μm N-type silicon wafer, performing surface texturing on the N-type silicon wafer to obtain an N-type silicon substrate 1-1, and then using a CVD method to deposit a 4 nm first intrinsic amorphous silicon 1-2 and a 20 nm N-type microcrystalline silicon layer (N-type silicon layer 1-3) on the front side of the N-type silicon substrate 1-1; and sequentially providing a 7 nm second intrinsic amorphous silicon 1-4 and a 30 nm P microcrystalline silicon layer (P-type silicon layer 1-5) on the back side of the N-type silicon substrate 1-1 to obtain a power generation device 1; Step 2: 10 nm thick In2O3:Sn thin films were deposited on the front and back of the power generation device using PVD as the first conductive functional layer 2 and the second conductive functional layer 5, respectively. The carrier mobility of both layers is 60 cm 2 / V·s, and the refractive index of both is 2.0.

[0050] Step 3: Prepare a Ag electrode on the upper surface of the conductive functional layer 2 by screen printing. The width of the Ag electrode is 30 μm and the height is 10 μm.

[0051] Step 4: Cover the conductive functional layer 2 and the electrode 3 on the side away from the power generation device with a photosensitive adhesive film, and expose and develop the film to expose the non-electrode area; Step 5: Deposit SiN on the front and back of the power generation device 1 by PECVD xThe laminated film is used as the first anti-reflection layer 4 and the second anti-reflection layer 7. Specifically, the refractive indexes of the first anti-reflection layer 4 and the second anti-reflection layer 7 are set to 2.8, 2.5, and 2.0 from the inside to the outside, and the thicknesses are 10 nm, 15 nm, and 25 nm respectively; The membrane was then backwashed to expose the electrodes.

[0052] Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is: (n1×d1+n2×d2+n3×d3+n4×d4)×4=(2.8×10+2.5×15+2.0×25+2.0×10)×4=542nm; Wherein, n1, n2, n3 are the refractive indices of each stack of the first anti-reflection layer 4, d1, d2, d3 are the thicknesses of each stack of the first anti-reflection layer 4; n4 is the refractive index of the first conductive functional layer 2, d4 is the thickness of the first conductive functional layer 2; Step 6: Photoinjection treatment of the device further enhances hydrogen passivation.

[0053] [Example 2] The rest is the same as Example 1, except that, in step 2, 15 nm thick In2O3:Sn thin films are deposited on the front and back sides of the power generation device by PVD as the first conductive functional layer 2 and the second conductive functional layer 5, respectively, and the refractive index thereof is 2.0; Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is 582 nm.

[0054] [Example 3] The rest is the same as in Example 1, except that in step 5, SiN is deposited on the device surface by PECVD. x The laminated film serves as the first anti-reflection layer 4 and the second anti-reflection layer 7. Specifically, the refractive indexes of the first anti-reflection layer 4 and the second anti-reflection layer 7 are set to 2.8, 2.5, and 2.0 from the inside to the outside, and the corresponding thicknesses are 10nm, 10nm, and 20nm.

[0055] Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is 532 nm.

[0056] [Example 4] The rest is the same as Example 1, except that, in step 2, PVD is used to deposit 20 nm thick In2O3:Sn films on the front and back sides of the power generation device.

[0057] Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is 622 nm.

[0058] [Example 5] The other aspects are the same as those of Example 1, except that, in step 2, 10 nm thick In2O3:Ta films are deposited on the front and back sides of the power generation device 1 by PVD, respectively, as the first conductive functional layer 2 and the second conductive functional layer 5, and the carrier mobility of both layers is 80 cm 2 / V·s, the refractive index of both is 2.0; In step 5, SiN is deposited on the device surface by PECVD. x The laminated film serves as the first anti-reflection layer 4 and the second anti-reflection layer 7. The refractive indexes of the first anti-reflection layer 4 and the second anti-reflection layer 7 are 3.0, 2.8, and 2.5 from the inside to the outside, and the thicknesses are 10 nm, 10 nm, and 20 nm respectively.

[0059] Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is 512 nm.

[0060] [Example 6] The rest is the same as Example 1, except for step 4 and step 5.

[0061] Step 4: Deposit SiN on the device surface using PECVD x The laminated film serves as the first anti-reflection layer 4 and the second anti-reflection layer 7. Specifically, the refractive indexes of the first anti-reflection layer 4 and the second anti-reflection layer 7 are set to 3.5, 3.2, and 2.5 from the inside to the outside, and the thicknesses are 10 nm, 15 nm, and 25 nm respectively.

[0062] Based on the thin film refraction principle, the optimal anti-reflection wavelength of the first anti-reflection layer 4 and the first conductive functional layer 2 as a whole is 662 nm.

[0063] [Example 7] The rest is the same as Example 1, except for step 4 and step 5.

[0064] Step 4: Deposit SiN on the device surface using PECVD x The laminated film serves as the first anti-reflection layer 4 and the second anti-reflection layer 7. Specifically, the refractive indexes of the first anti-reflection layer 4 and the second anti-reflection layer 7 are set to 2.8, 2.5, and 2.0 from the inside to the outside, and the thicknesses are 10 nm, 15 nm, and 25 nm respectively.

[0065] Step 5: The laser is aligned with the electrode position to perform film opening processing to expose the electrode. Specifically, the laser power can be set to 45W.

[0066] Step 6: The operation is the same as step 6 of Example 1.

[0067] [Comparative Example 1] Step 1: The operation is the same as step 1 of Example 1.

[0068] Step 2: Use PVD to deposit a 60nm thick ITO film on the front and back of the power generation device. The optimal anti-reflection wavelength of the ITO film is 480nm.

[0069] Step 3: The operation is the same as step 3 of Example 1.

[0070]

Test example

[0071] Table 1:

[0072] It can be seen from Table 1 above that the performance of Examples 1 to 7 is equal to or even better than that of Comparative Example 1, which is reflected in the fact that the filling factor and conversion efficiency are equal to or even higher than that of Comparative Example 1. This shows that the embodiment of the present application greatly reduces the growth cost of the TCO film while ensuring that the photoelectric performance of the two functional layers is equal to or even better than the original TCO, and thus greatly reduces the production cost of the photovoltaic heterojunction battery while maintaining or even improving the performance of the photovoltaic heterojunction battery. Furthermore, the performance of Example 4 is slightly lower than that of Examples 1 to 3, which may be due to the problem that the sum of the thickness of the conductive functional layer and the anti-reflection layer is slightly larger. The performance of Example 7 is slightly lower than that of Examples 1 to 3, which may be due to the fact that the refractive index of the anti-reflection layer is too high, and the anti-reflection effect of the anti-reflection layer based on the thin film interference principle is deteriorated, resulting in an increase in light reflection, a slight decrease in the short-circuit current of the device, and a slight decrease in efficiency. The performance of Example 8 is lower than that of Examples 1 to 7, which may be due to the fact that laser film opening may cause device damage.

[0073] It should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0074] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0075] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0076] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A photovoltaic heterojunction cell, characterized in that: A power generation device is included, wherein the power generation device includes a first surface and a second surface disposed opposite to each other; A first conductive functional layer is disposed on the first surface, and a second conductive functional layer is disposed on the second surface; A first electrode and a first anti-reflection layer are provided on a side of the first conductive functional layer away from the first surface; A second electrode and a second anti-reflection layer are disposed on a side of the second conductive functional layer away from the second surface.

2. The photovoltaic heterojunction cell according to claim 1, characterized in that: The refractive indexes of the first anti-reflection layer and the second anti-reflection layer are independently 2.0 to 3.0; and / or The thickness of the first anti-reflection layer and the second anti-reflection layer are independently 40 nm to 50 nm.

3. The photovoltaic heterojunction cell according to claim 2, characterized in that: The first anti-reflection layer is a stacked structure, and the refractive index of each stacked layer of the first anti-reflection layer decreases continuously from the direction close to the first conductive functional layer to the direction away from the first conductive functional layer; and / or The second anti-reflection layer is a stacked structure, and the refractive index of each stacked layer of the second anti-reflection layer decreases continuously in a direction from close to the second conductive functional layer to far away from the second conductive functional layer.

4. The photovoltaic heterojunction cell according to claim 3, characterized in that: In a direction from close to the first conductive functional layer to far away from the first conductive functional layer, the first anti-reflection layer includes a first stacked layer, a second stacked layer and a third stacked layer; Wherein, the thickness of the first stack is 10 nm to 15 nm, the thickness of the second stack is 10 nm to 15 nm, and the thickness of the third stack is 15 nm to 25 nm; and / or The refractive index of the first stack is 3.0 to 2.8, the refractive index of the second stack is 2.8 to 2.5, and the refractive index of the second stack is 2.5 to 2.

0.

5. The photovoltaic heterojunction cell according to claim 1, characterized in that: The thickness of the first conductive functional layer and the second conductive functional layer are independently 10 nm to 20 nm.

6. The photovoltaic heterojunction cell according to claim 1, characterized in that: The first conductive functional layer and the second conductive functional layer independently include one or more of tin-doped indium oxide and transition metal-doped indium oxide; and / or The first anti-reflection layer and the second anti-reflection layer each independently include SiN x 、AlO a 、SiO b N c , SiO2 or more.

7. The photovoltaic heterojunction cell according to claim 1, characterized in that: The power generation device comprises an N-type silicon substrate, and a first intrinsic amorphous silicon layer and an N-type silicon layer are sequentially arranged on the front side of the N-type silicon substrate; The back side of the N-type silicon substrate is provided with a second intrinsic amorphous silicon layer and a P-type silicon layer in sequence.

8. The photovoltaic heterojunction cell according to claim 7, characterized in that: The photovoltaic heterojunction cell satisfies at least one of the following characteristics: The thickness of the N-type silicon substrate is 110 μm to 150 μm; The thickness of the first intrinsic amorphous silicon is 4nm to 7nm; The thickness of the N-type silicon layer is 20nm to 25nm; The thickness of the second intrinsic amorphous silicon is 4nm to 7nm; The thickness of the P-type silicon layer is 25nm-30nm.

9. A method for preparing a photovoltaic heterojunction cell according to any one of claims 1 to 8, characterized in that: The following operations are included: Providing power generation devices; Depositing a first conductive functional layer on the front side of the power generation device, preparing a first electrode on the first conductive functional layer, depositing a first anti-reflection layer on the side of the first conductive functional layer and the first electrode away from the power generation device, and then performing a film opening treatment at the position of the first electrode to expose the first electrode; A second conductive functional layer is deposited on the back side of the power generation device, a second electrode is prepared on the second conductive functional layer, a second anti-reflection layer is deposited on the side of the second conductive functional layer and the second electrode away from the power generation device, and then a film opening treatment is performed at the position of the second electrode to expose the second electrode.

10. A method for preparing a photovoltaic heterojunction cell according to any one of claims 1 to 8, characterized in that: The following operations are included: Providing power generation devices; Depositing a first conductive functional layer on the front side of the power generation device; Depositing a second conductive functional layer on the back side of the power generation device; preparing a first electrode on the first conductive functional layer; preparing a second electrode on the second conductive functional layer; Covering the first conductive functional layer and the second conductive functional layer with photosensitive adhesive films respectively; performing exposure and development to expose the non-electrode area; After exposure, a first anti-reflection layer is deposited on a side of the photosensitive adhesive film away from the first conductive functional layer; After exposure, a second anti-reflection layer is deposited on a side of the photosensitive adhesive film away from the second conductive functional layer; The photosensitive adhesive film is removed to expose the first electrode and the second electrode.

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