Silicon-based solar cell passivation structure, preparation method thereof and silicon-based solar cell

Abstract

The invention provides a silicon-based solar cell passivation structure and a preparation method thereof, a silicon-based solar cell and a photovoltaic system. The silicon-based solar cell passivation structure comprises a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer and a silicon oxide layer which are stacked in sequence, and the second aluminum oxide layer is added, namely, the second aluminum oxide layer is prepared after the silicon nitride layer is prepared and before the silicon oxide layer is prepared. SiOx in the silicon oxide layer promotes formation of excessive ALO4 <-> units in the second aluminum oxide layer close to the silicon oxide layer, the negative charge density is increased, the chemical passivation effect, the field passivation effect and the PID resistance of the passivation structure are improved, the anti-reflection effect of the passivation structure is not affected, and the service life of the passivation structure is prolonged. And the open-circuit voltage, the cell efficiency and the anti-PID capability of the silicon-based solar cell are improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a silicon-based solar cell passivation structure and a preparation method thereof, a silicon-based solar cell, and a photovoltaic system. Background Art

[0002] Silicon-based solar cells are the most mainstream type of solar cells on the market. They use silicon as the main semiconductor material to convert sunlight into electrical energy. Silicon-based solar cells are mainly divided into two categories: P-type and N-type.

[0003] At present, the commonly used silicon-based solar cell passivation structures include: aluminum oxide film, silicon nitride film, SiO2 film; aluminum oxide film covers silicon nitride film to play the role of passivation and anti-reflection, and then add a layer of SiO2 layer to play the role of anti-reflection and anti-PID (Potential Induced Degradation) effect. In this type of silicon-based solar cell passivation structure, SiO2 film mainly plays the role of chemical passivation, so the field passivation ability of silicon-based solar cell passivation structure is poor.

[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] In view of the deficiencies in the prior art, the purpose of the present application is to provide a silicon-based solar cell passivation structure and a preparation method thereof, a silicon-based solar cell, and a photovoltaic system. The silicon-based solar cell passivation structure includes a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence. The addition of the second aluminum oxide layer improves the chemical passivation effect, field passivation effect, and anti-PID capability of the passivation structure, thereby improving the open circuit voltage, battery efficiency, and anti-PID capability of the silicon-based solar cell.

[0006] To achieve the above objectives, this application adopts the following technical solutions: A silicon-based solar cell passivation structure comprises a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer which are stacked in sequence.

[0007] In some embodiments, the thickness of the first aluminum oxide layer is 3 to 8 nm; The thickness of the silicon nitride layer is 65-75 nm; The thickness of the second aluminum oxide layer is 1-3 nm; The thickness of the silicon oxide layer is 1-2 nm.

[0008] In some embodiments, the silicon nitride layer includes 3 to 5 silicon nitride sub-layers stacked sequentially.

[0009] In some embodiments, when the silicon nitride layer includes a first layer to an Nth layer of silicon nitride sub-layers stacked sequentially: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5.

[0010] The present application also provides a method for preparing a silicon-based solar cell passivation structure, comprising: A silicon substrate is provided; a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer are sequentially prepared on the silicon substrate; wherein the silicon nitride layer comprises 3 to 5 sub-silicon nitride layers stacked sequentially.

[0011] In some embodiments, after forming the first aluminum oxide layer and before preparing the silicon nitride layer, the method further includes: performing a first annealing on the silicon substrate stacked with the first aluminum oxide layer; and / or After forming the second aluminum oxide layer and before preparing the silicon oxide layer, the method further comprises: The silicon substrate on which the second aluminum oxide layer is stacked is subjected to a second annealing.

[0012] In some embodiments, the preparation method of the first aluminum oxide layer comprises an atomic layer deposition method; when the silicon substrate stacked with the first aluminum oxide layer is subjected to a first annealing, the temperature is controlled at 400-500° C. and the time is controlled at 8-15 min; and / or The preparation method of the second aluminum oxide layer includes a plasma enhanced chemical vapor deposition method; when the silicon substrate stacked with the second aluminum oxide layer is subjected to a second annealing, the temperature is controlled at 300-400° C. and the time is controlled at 8-15 minutes.

[0013] In some embodiments, the method satisfies at least one of the following characteristics: (1) The thickness of the silicon nitride layer is 65-75 nm; (2) When the silicon nitride layer includes the first to Nth sub-silicon nitride layers stacked in sequence: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5; (3) in the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced; (4) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced from 2:1 to 1:1; (5) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the deposition rate of each silicon nitride sub-layer increases sequentially.

[0014] The present application also provides a silicon-based solar cell, comprising: The above silicon-based solar cell passivation structure; or The silicon-based solar cell passivation structure prepared by the above preparation method.

[0015] The present application also provides a photovoltaic system, comprising the above-mentioned silicon-based solar cell.

[0016] In the technical solution of the present application, the passivation structure of the silicon-based solar cell includes a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence, wherein the second aluminum oxide layer is added, that is, after the silicon nitride layer is prepared and before the silicon oxide layer is prepared, the second aluminum oxide layer is prepared, and the SiO x This promotes the formation of excess ALO in the adjacent second aluminum oxide layer. 4- The unit increases the negative charge density, improves the chemical passivation effect, field passivation effect and anti-PID ability of the passivation structure, does not affect the anti-reflection effect of the passivation structure, and plays a role in improving the open circuit voltage, cell efficiency and anti-PID ability of silicon-based solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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. Figure 1 This is a schematic structural diagram of the silicon-based solar cell passivation structure prepared in Example 1 of the present application; Numbers in the figure: 1, silicon substrate; 2, first aluminum oxide layer; 3, silicon nitride layer; 4, second aluminum oxide layer; 5, silicon oxide layer.

[0018] Figure 2 This is a graph showing the detection results of minority carrier lifetime and iVoc of the passivation structure of Example 16 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The present application provides a silicon-based solar cell passivation structure and a preparation method thereof, and a silicon-based solar cell. The silicon-based solar cell passivation structure comprises a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence. The second aluminum oxide layer is added, and the chemical passivation effect, field passivation effect, and anti-PID capability of the passivation structure are improved without affecting its anti-reflection effect, thereby improving the open circuit voltage, battery efficiency, and anti-PID (Potential Induced Degradation) capability of the silicon-based solar cell.

[0024] An embodiment of the present application provides a silicon-based solar cell passivation structure, comprising a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence.

[0025] It should be noted that the silicon-based solar cell passivation structure in the embodiment of the present application can be applied to P-type silicon-based solar cells and N-type silicon-based solar cells. When the silicon-based solar cell passivation structure is used for P-type silicon-based solar cells, the silicon substrate is selected to be a P-type silicon substrate; when the silicon-based solar cell passivation structure is used for N-type silicon-based solar cells, the silicon substrate is selected to be an N-type silicon substrate; in addition, the embodiment of the present application adds a second aluminum oxide layer, which can enhance the passivation effect of the passivation structure, and the passivation effect includes a chemical passivation effect and a field passivation effect.

[0026] In the embodiment of the present application, the first aluminum oxide layer is an aluminum oxide film; the preparation method of the first aluminum oxide layer can be selected from one or more of electrochemical oxidation, anodization, atomic layer deposition, evaporation, electron beam reaction evaporation, DC reaction magnetron sputtering, secondary anodization, and sol-gel method. The thickness of the first aluminum oxide layer can be greater than 0nm≤20nm (for example, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm).

[0027] In the embodiment of the present application, the second aluminum oxide layer is an aluminum oxide film; the preparation method of the second aluminum oxide layer can be selected from one or more of electrochemical oxidation, anodization, atomic layer deposition, evaporation, electron beam reaction evaporation, DC reaction magnetron sputtering, secondary anodization, and sol-gel method. The thickness of the second aluminum oxide layer can be greater than 0nm≤20nm (for example, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm).

[0028] In the embodiment of the present application, the silicon nitride layer is a silicon nitride film; the preparation method of the silicon nitride layer can be selected from one or more of chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), hot wire chemical vapor deposition (HW-CVD), electron cyclotron resonance (ECR), pulsed DC sputtering, multi-hollow remote plasma chemical vapor deposition, and plasma enhanced chemical vapor deposition (PECVD). The thickness of the silicon nitride layer can be greater than 0nm≤200nm (for example, 1nm, 2nm, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm).

[0029] In the embodiment of the present application, the silicon oxide layer is a silicon oxide film; the preparation method of the silicon oxide layer can be selected from one or more of reactive magnetron sputtering, plasma enhanced atomic layer deposition, microwave plasma assisted chemical vapor deposition, plasma enhanced chemical vapor deposition (PECVD), physical deposition or chemical vapor deposition, sol-gel method, and vacuum plating. The thickness of the silicon oxide layer can be greater than 0nm≤100nm (for example, 1nm, 2nm, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm).

[0030] In the embodiment of the present application, the first aluminum oxide layer and the second aluminum oxide layer are both Al2O3 films; the Al2O3 film can exhibit excellent passivation effect, thanks to its high internal (greater than 1012cm -2 ) of a fixed negative charge density (Qf), thereby obtaining a good field effect passivation effect; the silicon-based solar cell passivation structure provided by the embodiment of the present application comprises a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence, wherein the second aluminum oxide layer is added, that is, after the silicon nitride layer is prepared and before the silicon oxide layer is prepared, the second aluminum oxide layer is prepared, and the SiO in the silicon oxide layer x This promotes the formation of excess ALO in the adjacent second aluminum oxide layer. 4- The unit increases the negative charge density, improves the chemical passivation effect, field passivation effect and anti-PID ability of the passivation structure, does not affect the anti-reflection effect of the passivation structure, and plays a role in improving the open circuit voltage, cell efficiency and anti-PID ability of silicon-based solar cells.

[0031] In an optional embodiment, the thickness of the first aluminum oxide layer is 3-8 nm (e.g., 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm); The thickness of the silicon nitride layer is 65-75 nm (for example, 65 nm, 66 nm, 67 nm, 68 nm, 69 nm, 70 nm, 71 nm, 72 nm, 73 nm, 74 nm, 75 nm); The thickness of the second aluminum oxide layer is 1-3 nm (e.g., 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm); The thickness of the silicon oxide layer is 1-2 nm (for example, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2 nm).

[0032] The thickness of each layer of the silicon-based solar cell passivation structure provided in the embodiment of the present application will ultimately affect the anti-reflection effect, field passivation effect and anti-PID capability of the prepared silicon-based solar cell passivation structure; therefore, further optimizing the thickness of each layer can further enhance the anti-reflection effect, field passivation effect and anti-PID capability of the silicon-based solar cell passivation structure.

[0033] In an optional embodiment, the silicon nitride layer includes 3 to 5 sequentially stacked sub-silicon nitride layers, that is, the silicon nitride layer includes 3 sequentially stacked sub-silicon nitride layers, 4 sequentially stacked sub-silicon nitride layers, or 5 sequentially stacked sub-silicon nitride layers. The silicon nitride layer includes multiple sequentially stacked sub-silicon nitride layers, and the multiple stacked silicon nitride layers can affect the reflectivity of the passivation structure of the silicon-based solar cell, play a role in reducing the reflectivity, thereby improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0034] In an optional embodiment, when the silicon nitride layer includes a first layer to an Nth layer of silicon nitride sub-layers stacked sequentially: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5.

[0035] The thickness of the sub-silicon nitride layer located at one end in the thickness direction of the silicon nitride layer is higher than the thickness of the sub-silicon nitride layer located in the middle of the thickness direction of the silicon nitride layer; the thickness of the sub-silicon nitride layer located at the other end in the thickness direction of the silicon nitride layer is higher than the thickness of the sub-silicon nitride layer located in the middle of the thickness direction of the silicon nitride layer.

[0036] In the embodiment of the present application, the thickness of the sub-silicon nitride layer close to the first aluminum oxide layer and the thickness of the sub-silicon nitride layer close to the second aluminum oxide layer are both higher than the thickness of the sub-silicon nitride layer located in the middle of the thickness direction of the silicon nitride layer; in addition, the thickness of the sub-silicon nitride layer close to the first aluminum oxide layer and the thickness of the sub-silicon nitride layer close to the second aluminum oxide layer can be the same or different; the purpose of setting the thickness of the sub-silicon nitride layer in the silicon nitride layer to be thick at both ends and thin in the middle is: by controlling the thickness of the sub-silicon nitride layer, the reflectivity of the passivation structure of the silicon-based solar cell is affected, which plays a role in further reducing the reflectivity, thereby enhancing the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0037] The present application also provides a method for preparing a silicon-based solar cell passivation structure, comprising: providing a silicon substrate; A first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer are sequentially prepared on the silicon substrate; wherein the silicon nitride layer includes 3 to 5 sub-silicon nitride layers stacked sequentially.

[0038] The silicon nitride layer includes multiple layers of sequentially stacked sub-silicon nitride layers. The multiple layers of stacked silicon nitride layers can affect the reflectivity of the passivation structure of the silicon-based solar cell, play a role in reducing the reflectivity, and thus improve the anti-reflection effect of the passivation structure of the silicon-based solar cell. By sequentially preparing each layer on the silicon substrate, the combined use of field passivation and chemical passivation can be completed, and a better surface passivation effect can be achieved. Without affecting the anti-reflection effect of the passivation structure of the silicon-based solar cell, the field passivation effect and anti-PID ability of the passivation structure of the silicon-based solar cell are improved, thereby improving the open circuit voltage, cell efficiency and anti-PID ability of the silicon-based solar cell.

[0039] In an alternative embodiment: After forming the first aluminum oxide layer and before preparing the silicon nitride layer, the method further comprises: performing a first annealing on the silicon substrate stacked with the first aluminum oxide layer; and / or After forming the second aluminum oxide layer and before preparing the silicon oxide layer, the method further includes: performing a second annealing on the silicon substrate stacked with the second aluminum oxide layer.

[0040] In the embodiment of the present application, annealing is performed after the aluminum oxide layer is prepared, which can activate the H (hydrogen) passivation effect and further enhance the field passivation effect, thereby enhancing the field passivation effect of the passivation structure of the silicon-based solar cell.

[0041] In an optional embodiment, the preparation method of the first aluminum oxide layer comprises an atomic layer deposition method; when the silicon substrate stacked with the first aluminum oxide layer is subjected to a first annealing, the temperature is controlled at 400-500° C. and the time is controlled at 8-15 min; and / or The preparation method of the second aluminum oxide layer includes a plasma enhanced chemical vapor deposition method; when the silicon substrate stacked with the second aluminum oxide layer is subjected to a second annealing, the temperature is controlled at 300-400° C. and the time is controlled at 8-15 minutes.

[0042] In the embodiment of the present application, annealing is performed after the aluminum oxide layer is prepared, which can activate the H passivation effect and further enhance the field passivation effect, thereby enhancing the field passivation effect of the passivation structure of the silicon-based solar cell.

[0043] In an embodiment of the present application, the preparation method of the first aluminum oxide layer can be an atomic layer deposition method, and the density of the prepared aluminum oxide film is relatively high; the preparation method of the second aluminum oxide layer can be a plasma enhanced chemical vapor deposition method, and the density of the prepared aluminum oxide film is relatively low; by controlling the density and thickness of the aluminum oxide film, the reflectivity of the passivation structure of the silicon-based solar cell is affected, which further reduces the reflectivity, thereby improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0044] In an optional embodiment, the method satisfies at least one of the following characteristics: (1) The thickness of the silicon nitride layer is 65-75 nm; (2) When the silicon nitride layer includes the first to Nth sub-silicon nitride layers stacked in sequence: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5; (3) in the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced; (4) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced from 2:1 to 1:1; (5) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the deposition rate of each silicon nitride sub-layer increases sequentially.

[0045] In the embodiment of the present application, the thickness of the silicon nitride layer will ultimately affect the anti-reflection effect, field passivation effect and anti-PID capability of the prepared silicon-based solar cell passivation structure; optimizing the thickness of the silicon nitride layer can further enhance the anti-reflection effect, field passivation effect and anti-PID capability of the silicon-based solar cell passivation structure.

[0046] In the embodiment of the present application, the purpose of setting the thickness of the sub-silicon nitride layer in the silicon nitride layer to be thick at both ends and thin in the middle is: by controlling the thickness of the sub-silicon nitride layer, the reflectivity of the passivation structure of the silicon-based solar cell is affected, which plays a role in further reducing the reflectivity, thereby improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0047] In an embodiment of the present application, the silicon nitride layer includes 3 to 5 sub-silicon nitride layers stacked in sequence, and the optimal number of sub-silicon nitride layers is 3 layers; when preparing each sub-silicon nitride layer in sequence, the flow ratio of silane gas to ammonia gas gradually decreases, which can effectively reduce the reflectivity of the passivation structure of the silicon-based solar cell; preferably, the number of sub-silicon nitride layers is 3 layers, and when preparing the first sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 2:1; when preparing the second sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 1.5:1, and when preparing the third sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 1:1; wherein, the first sub-silicon nitride layer is close to the first aluminum oxide layer, and the third sub-silicon nitride layer is close to the second aluminum oxide layer; in an embodiment of the present application, the flow ratio of silane gas to ammonia gas is mainly controlled, and the flow rates of silane gas and ammonia gas can be set according to actual needs. Preferably, the flow rate of ammonia gas is 9000-11000 sccm, and correspondingly, the flow rate of silane gas is 9000-22000 sccm.

[0048] In the embodiment of the present application, the thickness of the sub-silicon nitride layer in the silicon nitride layer is set to be thick at both ends and thin in the middle, and when each sub-silicon nitride layer is sequentially prepared on the first aluminum oxide layer, the deposition rate of each sub-silicon nitride layer is gradually increased, so that the silicon nitride layer can achieve a better hydrogen passivation effect with the first aluminum oxide layer and the second aluminum oxide layer, thereby improving the passivation effect of the silicon-based solar cell passivation structure. In the embodiment of the present application, the deposition rate of each sub-silicon nitride layer is mainly controlled to gradually increase, and the deposition rate of each sub-silicon nitride layer can be set according to actual needs. Preferably, the number of sub-silicon nitride layers is 3, silane and ammonia are introduced into the PECVD equipment, and when preparing the first sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 15000w, when preparing the second sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 16000w, and when preparing the third sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 17000w; by controlling the RF power of the PECVD equipment, the deposition rate of each sub-silicon nitride layer is gradually increased, so that the silicon nitride layer can achieve better hydrogen passivation effect with the first aluminum oxide layer and the second aluminum oxide layer, thereby improving the passivation effect of the passivation structure of the silicon-based solar cell.

[0049] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0050] Example 1 A method for preparing a silicon-based solar cell passivation structure comprises the following steps: Step (1): Take an N-type silicon wafer as a silicon substrate 1; use a PECVD device to deposit a layer of aluminum oxide film on the silicon substrate 1 as a first aluminum oxide layer 2, and the thickness of the first aluminum oxide layer 2 is 10 nm.

[0051] Step (2): introducing silane and ammonia into the PECVD equipment, with a silane flow rate of 2000 sccm, an ammonia flow rate of 9000 sccm, a pressure of 1500 mTorr, a power of 12500 w, and a silicon nitride coating temperature zone of 400°C; preparing a silicon nitride layer 3 with a thickness of 100 nm on the first aluminum oxide layer 2.

[0052] Step (3): purge and pre-cool the PECVD device until the temperature drops to 300° C., introduce TMA (trimethylaluminum) and water gas in sequence, with a TMA flow rate of 19 sccm and a water flow rate of 20 sccm, and deposit a 10 nm thick aluminum oxide film on the silicon nitride layer 3 as the second aluminum oxide layer 4; Step (4): Silane (SiNH4) gas and nitrous oxide (N2O) gas are introduced into the PECVD device, the silane flow rate is 800sccm, the nitrous oxide flow rate is 10000sccm, the pressure is 1500mTorr, the RF power is 11000w, and the reaction temperature is 300°C, that is, a silicon oxide layer 5 with a thickness of 10nm is prepared on the second aluminum oxide layer 4. The silicon-based solar cell passivation structure prepared in the embodiment of the present application is as follows Figure 1 shown.

[0053] Example 2 The silicon-based solar cell passivation structure of Example 2 is prepared by referring to the preparation method of Example 1, with the only difference being that in Example 2, the thickness of the first aluminum oxide layer 2 is 3 nm, the thickness of the silicon nitride layer 3 is 65 nm, the thickness of the second aluminum oxide layer 4 is 1 nm, and the thickness of the silicon oxide layer 5 is 1 nm.

[0054] Example 3 The silicon-based solar cell passivation structure of Example 3 was prepared by referring to the preparation method of Example 2, except that step (2) in Example 3 was as follows: silane and ammonia were introduced into the PECVD device, the silane flow rate was 2000sccm, the ammonia flow rate was 9000sccm, the pressure was 1500mTorr, the power was 12500w, and the temperature of the silicon nitride coating temperature zone was 400°C; a first sub-silicon nitride layer with a thickness of 22nm was prepared on the first aluminum oxide layer 2; and the first sub-silicon nitride layer was completed. After preparation, a second sub-silicon nitride layer with a thickness of 22nm is prepared on the first sub-silicon nitride layer; after completing the preparation of the second sub-silicon nitride layer, a third sub-silicon nitride layer with a thickness of 21nm is prepared on the second sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, and the third sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the flow ratio of silane gas and ammonia gas is consistent, and the deposition rate of each sub-silicon nitride layer is consistent.

[0055] Example 4 The silicon-based solar cell passivation structure of Example 4 was prepared by referring to the preparation method of Example 2, except that step (2) in Example 4 was as follows: introducing silane and ammonia into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the temperature in the silicon nitride coating temperature zone was 400°C; preparing a first sub-silicon nitride layer with a thickness of 10 nm on the first aluminum oxide layer 2; after completing the preparation of the first sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 10 nm on the first sub-silicon nitride layer; after completing the preparation of the second sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 10 nm on the first sub-silicon nitride layer; A third sub-silicon nitride layer with a thickness of 10nm is prepared on the second sub-silicon nitride layer; after the preparation of the third sub-silicon nitride layer is completed, a fourth sub-silicon nitride layer with a thickness of 10nm is continuously prepared on the third sub-silicon nitride layer; after the preparation of the fourth sub-silicon nitride layer is completed, a fifth sub-silicon nitride layer with a thickness of 25nm is continuously prepared on the fourth sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, the third sub-silicon nitride layer, the fourth sub-silicon nitride layer, and the fifth sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the flow ratio of silane gas and ammonia gas is consistent, and the deposition rate of each sub-silicon nitride layer is consistent.

[0056] Example 5 The silicon-based solar cell passivation structure of Example 5 was prepared by referring to the preparation method of Example 2, except that step (2) in Example 5 is as follows: silane and ammonia are introduced into the PECVD device, the silane flow rate is 2000sccm, the ammonia flow rate is 9000sccm, the pressure is 1500mTorr, the power is 12500w, and the temperature of the silicon nitride coating temperature zone is 400°C; a first sub-silicon nitride layer with a thickness of 25nm is prepared on the first aluminum oxide layer 2; and the first sub-silicon nitride layer is completed. After preparation, a second sub-silicon nitride layer with a thickness of 15 nm is prepared on the first sub-silicon nitride layer; after completing the preparation of the second sub-silicon nitride layer, a third sub-silicon nitride layer with a thickness of 25 nm is prepared on the second sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, and the third sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65 nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the flow ratio of silane gas and ammonia gas is consistent, and the deposition rate of each sub-silicon nitride layer is consistent.

[0057] Example 6 The silicon-based solar cell passivation structure of Example 6 is prepared by referring to the preparation method of Example 2, with the only difference being that Example 6 also includes: after forming the first aluminum oxide layer 2 and before preparing the silicon nitride layer 3, the silicon substrate stacked with the first aluminum oxide layer 2 is subjected to a first annealing, and the temperature is controlled at 400°C and the time is controlled at 10 minutes.

[0058] Example 7 The silicon-based solar cell passivation structure of Example 7 is prepared by referring to the preparation method of Example 2, with the only difference being that Example 7 also includes: after forming the second aluminum oxide layer 4 and before preparing the silicon oxide layer 5, the silicon substrate stacked with the second aluminum oxide layer 4 is subjected to a second annealing, and the temperature is controlled at 400°C and the time is controlled at 10 minutes.

[0059] Example 8 The silicon-based solar cell passivation structure of Example 8 is prepared by referring to the preparation method of Example 2, with the only difference being that Example 8 also includes: 1) after forming the first aluminum oxide layer 2 and before preparing the silicon nitride layer 3, the silicon substrate stacked with the first aluminum oxide layer 2 is subjected to a first annealing, with the temperature controlled at 400°C and the time controlled at 10 min; 2) after forming the second aluminum oxide layer 4 and before preparing the silicon oxide layer 5, the silicon substrate stacked with the second aluminum oxide layer 4 is subjected to a second annealing, with the temperature controlled at 400°C and the time controlled at 10 min.

[0060] Example 9 The silicon-based solar cell passivation structure of Example 9 was prepared by referring to the preparation method of Example 1, except that step (1) in Example 9 is: taking an N-type silicon wafer as the silicon substrate 1; and using an ALD device to deposit a layer of aluminum oxide film on the silicon substrate 1 as the first aluminum oxide layer 2, wherein the thickness of the first aluminum oxide layer 2 is 10 nm.

[0061] Example 10 The silicon-based solar cell passivation structure of Example 10 was prepared by referring to the preparation method of Example 2, except that step (1) in Example 10 was as follows: taking an N-type silicon wafer as the silicon substrate 1; and using an ALD device to deposit a layer of aluminum oxide film on the silicon substrate 1 as the first aluminum oxide layer 2, wherein the thickness of the first aluminum oxide layer 2 was 3 nm.

[0062] Embodiment 11 The silicon-based solar cell passivation structure of Example 11 was prepared by referring to the preparation method of Example 3, except that step (2) in Example 11 was as follows: silane and ammonia were introduced into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the silicon nitride coating temperature was 400° C.; a first sub-silicon nitride layer with a thickness of 22 nm was prepared on the first aluminum oxide layer 2; after the preparation of the first sub-silicon nitride layer was completed, a second sub-silicon nitride layer with a thickness of 22 nm was continuously prepared on the first sub-silicon nitride layer; and the second sub-silicon nitride layer was completed. After the preparation of the layer, a third sub-silicon nitride layer with a thickness of 21nm is prepared on the second sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, and the third sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the deposition rate of each sub-silicon nitride layer is consistent, but the flow ratio of silane gas to ammonia gas gradually decreases, specifically, when preparing the first sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 2; when preparing the second sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 1.5; when preparing the third sub-silicon nitride layer, the flow ratio of silane gas to ammonia gas is 1.

[0063] Example 12 The silicon-based solar cell passivation structure of Example 12 was prepared by referring to the preparation method of Example 3, except that step (2) in Example 12 was as follows: introducing silane and ammonia into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the temperature in the silicon nitride coating temperature zone was 400° C.; preparing a first sub-silicon nitride layer with a thickness of 22 nm on the first aluminum oxide layer 2; after completing the preparation of the first sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 22 nm on the first sub-silicon nitride layer; completing the preparation of the second sub-nitride layer After the preparation of the silicon layer, a third silicon nitride layer with a thickness of 21 nm is prepared on the second silicon nitride layer; the first silicon nitride layer, the second silicon nitride layer, and the third silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65 nm; it should be noted that when preparing each silicon nitride layer in this embodiment, the deposition rate of each silicon nitride layer is consistent, but the flow ratio of silane gas to ammonia gas gradually decreases. Specifically, when preparing the first silicon nitride layer, the flow ratio of silane gas to ammonia gas is 3; when preparing the second silicon nitride layer, the flow ratio of silane gas to ammonia gas is 2; when preparing the third silicon nitride layer, the flow ratio of silane gas to ammonia gas is 1.

[0064] Embodiment 13 The silicon-based solar cell passivation structure of Example 13 was prepared by referring to the preparation method of Example 3, except that step (2) in Example 13 was as follows: introducing silane and ammonia into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the temperature in the silicon nitride coating temperature zone was 400° C.; preparing a first sub-silicon nitride layer with a thickness of 22 nm on the first aluminum oxide layer 2; after completing the preparation of the first sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 22 nm on the first sub-silicon nitride layer; completing the preparation of the second sub-nitride layer After the preparation of the silicon layer, a third silicon nitride layer with a thickness of 21 nm is prepared on the second silicon nitride layer; the first silicon nitride layer, the second silicon nitride layer, and the third silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65 nm; it should be noted that when preparing each silicon nitride layer in this embodiment, the deposition rate of each silicon nitride layer is consistent, but the flow ratio of silane gas to ammonia gradually increases. Specifically, when preparing the first silicon nitride layer, the flow ratio of silane gas to ammonia is 1; when preparing the second silicon nitride layer, the flow ratio of silane gas to ammonia is 2; when preparing the third silicon nitride layer, the flow ratio of silane gas to ammonia is 3.

[0065] Embodiment 14 The silicon-based solar cell passivation structure of Example 14 was prepared by referring to the preparation method of Example 5, except that step (2) in Example 14 was as follows: introducing silane and ammonia into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the temperature in the silicon nitride coating temperature zone was 400°C; preparing a first sub-silicon nitride layer with a thickness of 25 nm on the first aluminum oxide layer 2; after completing the preparation of the first sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 15 nm on the first sub-silicon nitride layer; after completing the preparation of the second sub-silicon nitride layer, continuing to prepare a third sub-silicon nitride layer with a thickness of 25 nm on the second sub-silicon nitride layer. sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, and the third sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the flow ratio of silane gas and ammonia gas is consistent, and the deposition rate of each sub-silicon nitride layer gradually increases; specifically, when preparing the first sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 15000w, when preparing the second sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 16000w, and when preparing the third sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 17000w; by controlling the RF power of the PECVD equipment, the deposition rate of each sub-silicon nitride layer is gradually increased.

[0066] Embodiment 15 The silicon-based solar cell passivation structure of Example 15 was prepared by referring to the preparation method of Example 5, except that step (2) in Example 15 was as follows: introducing silane and ammonia into the PECVD device, the silane flow rate was 2000 sccm, the ammonia flow rate was 9000 sccm, the pressure was 1500 mTorr, the power was 12500 w, and the silicon nitride coating temperature zone temperature was 400°C; preparing a first sub-silicon nitride layer with a thickness of 25 nm on the first aluminum oxide layer 2; after completing the preparation of the first sub-silicon nitride layer, continuing to prepare a second sub-silicon nitride layer with a thickness of 15 nm on the first sub-silicon nitride layer; after completing the preparation of the second sub-silicon nitride layer, continuing to prepare a third sub-silicon nitride layer with a thickness of 25 nm on the second sub-silicon nitride layer. sub-silicon nitride layer; the first sub-silicon nitride layer, the second sub-silicon nitride layer, and the third sub-silicon nitride layer stacked in sequence are silicon nitride layer 3, and the thickness of silicon nitride layer 3 is 65nm; it should be noted that when preparing each sub-silicon nitride layer in this embodiment, the flow ratio of silane gas and ammonia gas is consistent, and the deposition rate of each sub-silicon nitride layer gradually decreases; specifically, when preparing the first sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 17000w, when preparing the second sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 16000w, and when preparing the third sub-silicon nitride layer, the RF power of the PECVD equipment is controlled to be 15000w; by controlling the RF power of the PECVD equipment, the deposition rate of each sub-silicon nitride layer is gradually reduced.

[0067] Example 16 A method for preparing a silicon-based solar cell passivation structure comprises the following steps: Step (1): taking an N-type silicon wafer as a silicon substrate 1; using a tubular ALD device to deposit a layer of aluminum oxide film on the silicon substrate 1 as a first aluminum oxide layer 2, the thickness of the first aluminum oxide layer 2 being 3 nm; using the tubular ALD to deposit the first aluminum oxide layer 2 using precursors of TMA (trimethylaluminum) and water; the deposition method is: circulating TMA and water into the furnace tube in sequence, the number of cycles being 30, the pulse time being 5 s, and the purge time being 6 s.

[0068] Step (2): After depositing the first aluminum oxide layer 2, the silicon substrate 1 stacked with the first aluminum oxide layer 2 is subjected to a first annealing to activate the H passivation effect and obtain a first annealed silicon substrate. The first annealing is performed using a PECVD device, an annealing atmosphere of nitrogen, an annealing temperature of 400°C, and an annealing time of 10 minutes.

[0069] Step (3): After annealing, silane and ammonia are introduced into the PECVD device, the silane flow rate is 2000sccm, the ammonia flow rate is 9000sccm, the pressure is 1500mTorr, the power is 12500w, and the temperature of the silicon nitride coating temperature zone is 400°C; a silicon nitride layer 3 with a thickness of 65nm is prepared on the silicon substrate annealed for the first time.

[0070] Step (4): purge and pre-cool the PECVD device until the temperature drops to 300°C, introduce TMA and water gas in sequence, the TMA flow rate is 19 sccm, the water flow rate is 20 sccm, and the number of cycles is 15, that is, a 1 nm thick aluminum oxide film is plated on the silicon nitride layer 3 as the second aluminum oxide layer 4; after the coating is completed, purge and vacuum are performed to remove the reaction gas, then heat to 400°C, introduce nitrogen, and perform a second annealing at a constant temperature in a nitrogen atmosphere. The annealing time of the second annealing is 10 min. After the annealing is completed, purge and vacuum are performed.

[0071] Step (5): Silane (SiNH4) gas and nitrous oxide (N2O) gas are introduced into the PECVD device, the silane flow rate is 800 sccm, the nitrous oxide flow rate is 10000 sccm, the pressure is 1500 mTorr, the RF power is 11000 w, and the reaction temperature is 400°C, so that a silicon oxide layer 5 with a thickness of 1 nm is prepared on the second aluminum oxide layer 4.

[0072] Comparative Example 1 A method for preparing a silicon-based solar cell passivation structure comprises the following steps: Step (1): Take an N-type silicon wafer as a silicon substrate 1; use a PECVD device to deposit a layer of aluminum oxide film on the silicon substrate 1 as a first aluminum oxide layer 2, and the thickness of the first aluminum oxide layer 2 is 10 nm.

[0073] Step (2): introducing silane and ammonia into the PECVD equipment, with a silane flow rate of 2000 sccm, an ammonia flow rate of 9000 sccm, a pressure of 1500 mTorr, a power of 12500 w, and a silicon nitride coating temperature zone of 400°C; preparing a silicon nitride layer 3 with a thickness of 100 nm on the first aluminum oxide layer 2.

[0074] Step (3): silane (SiNH4) gas and nitrous oxide (N2O) gas are introduced into the PECVD device, the silane flow rate is 800sccm, the nitrous oxide flow rate is 10000sccm, the pressure is 1500mTorr, the RF power is 11000w, and the reaction temperature is 400°C, so that a silicon oxide layer 5 with a thickness of 10nm is prepared on the silicon nitride layer 3; that is, the second aluminum oxide layer 4 is not provided in Comparative Example 1.

[0075] The silicon-based solar cell passivation structures prepared in the above-mentioned embodiments and comparative examples were tested, wherein the test results of embodiment 16 and comparative example 1 are shown in Tables 1 and 2 below: Table 1

[0076] Table 2

[0077] Referring to the test results of Example 16 and Comparative Example 1, it can be seen that the minority carrier lifetime and iVoc (the output voltage of the battery at the maximum power point) of the silicon-based solar cell passivation structure in Example 16 are significantly higher than those in Comparative Example 1. And referring to the fluctuation of the minority carrier lifetime and the fluctuation of iVoc, it can be seen that the uniformity of various parameters in Example 16 is better than that in Comparative Example 1, which also shows that the passivation effect of the silicon-based solar cell passivation structure in Example 16 is improved compared with Comparative Example 1.

[0078] The test results of minority carrier lifetime and iVoc of Example 16 and Comparative Example 1 are as follows: Figure 2 As shown, Figure 2 The conventional passivation structure in the example refers to the silicon-based solar cell passivation structure in Comparative Example 1. Figure 2 The laminated aluminum oxide structure refers to the silicon-based solar cell passivation structure in Example 16.

[0079] Referring to the test results of Example 16 and Comparative Example 1, it can be seen that the reflectivity of the silicon-based solar cell passivation structure in Example 16 is significantly lower than that in Comparative Example 1. It can also be seen that compared with Comparative Example 1, the anti-reflection effect of the silicon-based solar cell passivation structure in Example 16 is improved.

[0080] The silicon-based solar cell passivation structures prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 3 below.

[0081] Table 3 Performance data of silicon-based solar cell passivation structure

[0082] Referring to the data of the above-mentioned embodiments 1-2 and comparative example 1, it can be seen that the embodiments of the present application provide a silicon-based solar cell passivation structure, comprising a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence, and the second aluminum oxide layer is added. Without affecting its anti-reflection effect, the field passivation effect and anti-PID ability of the passivation structure are improved, thereby improving the open circuit voltage, battery efficiency and anti-PID ability of the silicon-based solar cell.

[0083] Referring to the data of the above-mentioned Examples 1-2, it can be seen that the thickness of each layer will ultimately affect the anti-reflection effect, field passivation effect and anti-PID capability of the prepared silicon-based solar cell passivation structure; therefore, further optimizing the thickness of each layer can further enhance the anti-reflection effect, field passivation effect and anti-PID capability of the silicon-based solar cell passivation structure.

[0084] Referring to the data of the above-mentioned embodiments 1-2 and 3-5, it can be seen that the silicon nitride layer includes 3 to 5 sub-silicon nitride layers stacked in sequence. The multi-layer stacked silicon nitride layers can affect the reflectivity of the passivation structure of the silicon-based solar cell, play a role in reducing the reflectivity, thereby improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0085] Referring to the data of the above-mentioned Examples 3-5, it can be seen that by setting the thickness of the sub-silicon nitride layer in the silicon nitride layer to be thick at both ends and thin in the middle, the thickness of the sub-silicon nitride layer can be controlled to affect the reflectivity of the passivation structure of the silicon-based solar cell, thereby further reducing the reflectivity and improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0086] According to the data of the above-mentioned Example 2 and Examples 6-8, annealing is performed after the aluminum oxide layer is prepared, which can activate the H passivation effect and further enhance the field passivation effect, thereby enhancing the field passivation effect of the passivation structure of the silicon-based solar cell.

[0087] Referring to the data of the above-mentioned Examples 1-2 and Examples 9-10, it can be seen that the preparation method of the first aluminum oxide layer is the atomic layer deposition method, and the density of the prepared aluminum oxide film is relatively high; the preparation method of the second aluminum oxide layer is the plasma enhanced chemical vapor deposition method, and the density of the prepared aluminum oxide film is relatively low; by controlling the density and thickness of the aluminum oxide film, the reflectivity of the passivation structure of the silicon-based solar cell is affected, which plays a role in further reducing the reflectivity, thereby improving the anti-reflection effect of the passivation structure of the silicon-based solar cell.

[0088] Referring to the data of the above-mentioned Example 3 and Examples 11-13, it can be seen that when preparing each silicon nitride sub-layer in sequence, the flow ratio of silane gas to ammonia gas is gradually reduced, which can effectively reduce the reflectivity of the passivation structure of the silicon-based solar cell.

[0089] Referring to the data of the above-mentioned Examples 5 and 14-15, it can be seen that the thickness of the sub-silicon nitride layer in the silicon nitride layer is set to be thick at both ends and thin in the middle, and when each sub-silicon nitride layer is prepared sequentially on the first aluminum oxide layer, the deposition rate of each sub-silicon nitride layer gradually increases, so that the silicon nitride layer can achieve better hydrogen passivation effect with the first aluminum oxide layer and the second aluminum oxide layer, thereby improving the passivation effect of the passivation structure of the silicon-based solar cell.

[0090] In summary, the passivation structure of the silicon-based solar cell of the present application includes a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer stacked in sequence. The addition of the second aluminum oxide layer improves the chemical passivation effect, field passivation effect, and anti-PID capability of the passivation structure, thereby improving the open circuit voltage, battery efficiency, and anti-PID capability of the silicon-based solar cell.

[0091] The present application can provide a silicon-based solar cell, comprising: The above silicon-based solar cell passivation structure; or The silicon-based solar cell passivation structure prepared by the above preparation method has the same advantages as the above silicon-based solar cell passivation structure.

[0092] The embodiment of the present application can provide a photovoltaic system, including the above-mentioned silicon-based solar cell. The advantages of the above-mentioned silicon-based solar cell are also possessed by the photovoltaic system, which will not be repeated here. The above-mentioned photovoltaic system has a wide range of applications, not only limited to photovoltaic power stations, such as ground power stations, rooftop power stations and water power stations, but also includes various equipment and devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars and solar buildings. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be used in all fields where solar energy is required for power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components may form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid and then connected to the mains network to realize solar power supply.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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 silicon-based solar cell passivation structure, characterized in that: The invention comprises a silicon substrate, a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer and a silicon oxide layer which are stacked in sequence.

2. The silicon-based solar cell passivation structure according to claim 1, characterized in that: The thickness of the first aluminum oxide layer is 3-8 nm; The thickness of the silicon nitride layer is 65-75 nm; The thickness of the second aluminum oxide layer is 1-3 nm; The thickness of the silicon oxide layer is 1-2 nm.

3. The silicon-based solar cell passivation structure according to any one of claims 1 to 2, characterized in that: The silicon nitride layer includes 3 to 5 silicon nitride sub-layers stacked in sequence.

4. The silicon-based solar cell passivation structure according to claim 3, characterized in that: When the silicon nitride layer includes the first to Nth sub-silicon nitride layers stacked in sequence: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5.

5. A method for preparing a passivation structure of a silicon-based solar cell, characterized in that: include: providing a silicon substrate; Sequentially preparing a first aluminum oxide layer, a silicon nitride layer, a second aluminum oxide layer, and a silicon oxide layer on the silicon substrate; Wherein, the silicon nitride layer includes 3 to 5 silicon nitride sub-layers stacked in sequence.

6. The preparation method according to claim 5, characterized in that: After forming the first aluminum oxide layer and before preparing the silicon nitride layer, the method further comprises: performing a first annealing on the silicon substrate stacked with the first aluminum oxide layer; and / or After forming the second aluminum oxide layer and before preparing the silicon oxide layer, the method further includes: performing a second annealing on the silicon substrate stacked with the second aluminum oxide layer.

7. The preparation method according to claim 6, characterized in that: The preparation method of the first aluminum oxide layer comprises an atomic layer deposition method; when the silicon substrate stacked with the first aluminum oxide layer is subjected to a first annealing, the temperature is controlled at 400-500° C. and the time is controlled at 8-15 min; and / or The preparation method of the second aluminum oxide layer includes a plasma enhanced chemical vapor deposition method; when the silicon substrate stacked with the second aluminum oxide layer is subjected to a second annealing, the temperature is controlled at 300-400° C. and the time is controlled at 8-15 minutes.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The method satisfies at least one of the following characteristics: (1) The thickness of the silicon nitride layer is 65-75 nm; (2) When the silicon nitride layer includes the first to Nth sub-silicon nitride layers stacked in sequence: The thickness of the first silicon nitride sub-layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the Nth silicon nitride sub-layer; The thickness of the N-th silicon nitride layer is greater than the thickness of any silicon nitride sub-layer between the first silicon nitride sub-layer and the N-th silicon nitride sub-layer; Where N is equal to 3, 4 or 5; (3) in the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced; (4) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the flow ratio of silane gas to ammonia gas is gradually reduced from 2:1 to 1:1; (5) In the process of sequentially preparing each silicon nitride sub-layer on the first aluminum oxide layer, the deposition rate of each silicon nitride sub-layer increases sequentially.

9. A silicon-based solar cell, characterized in that: include: The silicon-based solar cell passivation structure according to any one of claims 1 to 4; or A silicon-based solar cell passivation structure prepared by the preparation method according to any one of claims 5 to 8.

10. A photovoltaic system, characterized in that: Comprising the silicon-based solar cell as claimed in claim 9.

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