Photovoltaic cell and method for producing a photovoltaic cell, photovoltaic module

Abstract

The application relates to a photovoltaic cell and a preparation method thereof, and a photovoltaic module. The preparation method of the photovoltaic cell comprises the following steps: providing a photovoltaic cell intermediate body, wherein the photovoltaic cell intermediate body comprises a silicon substrate and an aluminum oxide layer located on at least one surface of the silicon substrate; and performing plasma nitriding treatment on the aluminum oxide layer by using a process gas comprising silane and ammonia, so that the aluminum oxide layer is converted into an aluminum oxynitride layer, and a silicon nitride layer is formed on the surface of the aluminum oxynitride layer away from the silicon substrate. The preparation method of the photovoltaic cell can reduce damage to the film layer in the preparation process of the aluminum oxynitride layer, reduce the interface defect state density, improve the passivation effect, and further improve the conversion efficiency of the photovoltaic cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic, in particular to a photovoltaic cell and a preparation method thereof, and a photovoltaic module. BACKGROUND

[0002] Silicon-based photovoltaic cells are widely used at present. In silicon-based photovoltaic cells, P-type silicon and N-type silicon are formed by doping, and a PN junction is formed at the junction of the two, generating an internal electric field. In photovoltaic cells, the passivation layer is one of the key components for improving the photoelectric conversion efficiency of the photovoltaic cell, which mainly realizes this goal by passivating the doped silicon layer to reduce surface recombination. However, in traditional silicon-based photovoltaic cells, the passivation layer has limited passivation performance on the doped silicon layer. SUMMARY

[0003] Therefore, it is necessary to provide a photovoltaic cell and a preparation method thereof, and a photovoltaic module. The preparation method of the photovoltaic cell of the present application can reduce damage to the film layer during the preparation of the aluminum oxynitride layer, reduce the interface defect state density, improve the passivation effect, and thus improve the conversion efficiency of the photovoltaic cell.

[0004] In a first aspect, the present application provides a preparation method of a photovoltaic cell, comprising the following steps:

[0005] providing a photovoltaic cell intermediate, the photovoltaic cell intermediate comprising a silicon substrate and an aluminum oxide layer on at least one surface of the silicon substrate;

[0006] performing plasma nitridation treatment on the aluminum oxide layer using a process gas comprising silane and ammonia, so that the aluminum oxide layer is converted into an aluminum oxynitride layer, and a silicon nitride layer is formed on the surface of the aluminum oxynitride layer away from the silicon substrate.

[0007] In some embodiments, the flow ratio of ammonia to silane in the process gas is (100-1000): 1.

[0008] In some embodiments, the flow rate of silane in the process gas is 0.1-1 sccm, and the flow rate of ammonia is 100-300 sccm.

[0009] In some embodiments, the difference between the thickness of the aluminum oxide layer and the aluminum oxynitride layer is less than or equal to 1 nm.

[0010] In some embodiments, the power of the plasma nitridation treatment is 200-500 W.

[0011] In some embodiments, the pressure of the plasma nitridation treatment is 500-1000 mTorr.

[0012] In some embodiments, the temperature of the plasma nitridation process is 350-450 °C.

[0013] In some embodiments, the time of the plasma nitridation process is 1-5 min.

[0014] In some embodiments, the plasma nitridation process satisfies at least one of the following characteristics:

[0015] (1) the nitrogen concentration in the aluminum oxynitride layer is controlled to be 5x10 20 cm -3 -1x10 22 cm -3 .

[0016] (2) the thickness of the silicon nitride layer is controlled to be 1-3 nm.

[0017] In some embodiments, the method for preparing the photovoltaic cell intermediate comprises the following steps:

[0018] providing a silicon substrate;

[0019] forming a first doped silicon layer and a second doped silicon layer on the opposite surfaces of the silicon substrate, respectively, the doping type of the first doped silicon layer being P-type doping, and the doping type of the second doped silicon layer being N-type doping;

[0020] forming the aluminum oxide layer on the surface of the first doped silicon layer away from the silicon substrate.

[0021] In a second aspect, the present application provides a photovoltaic cell, comprising: a silicon substrate, and an aluminum oxynitride layer and a silicon nitride layer stacked on the surface of the silicon substrate, the aluminum oxynitride layer being located between the silicon nitride layer and the silicon substrate, and the thickness of the silicon nitride layer being 1-3 nm.

[0022] In some embodiments, the silicon substrate has a first surface and a second surface arranged oppositely;

[0023] the first surface is sequentially stacked with a first doped silicon layer, an aluminum oxynitride layer, a silicon nitride layer, and a first anti-reflection layer; the doping type of the first doped silicon layer is P-type doping; the first anti-reflection layer is provided with a first electrode, and the first electrode is electrically connected to the first doped silicon layer;

[0024] the second surface is sequentially stacked with a tunneling oxide layer, a second doped silicon layer, and a second anti-reflection layer; the doping type of the second doped silicon layer is N-type doping; the second anti-reflection layer is provided with a second electrode, and the second electrode is electrically connected to the second doped silicon layer.

[0025] Thirdly, this application provides a photovoltaic module, comprising:

[0026] Cover plate;

[0027] At least one battery string, the battery string comprising a photovoltaic cell prepared by the method described in any one of the above-mentioned photovoltaic cell preparation methods, or a photovoltaic cell described in any one of the above-mentioned photovoltaic cell preparation methods;

[0028] And an encapsulation layer, which is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

[0029] In traditional plasma nitriding, a process gas consisting only of ammonia is used. The bombardment of high-energy hydrogen ions (H+) causes damage to the alumina layer surface, resulting in an interface state defect density as high as 1×10⁻⁶. 12 cm -2 eV -1 The above describes the method for fabricating photovoltaic cells. In this method, a process gas including silane and ammonia is used to perform plasma nitriding treatment on the alumina layer, transforming it into an aluminum oxynitride layer. During the plasma nitriding process, silane reacts with high-energy hydrogen ions as follows: SiH₄ + H⁺ + →SiH3+H2, which reduces the energy of hydrogen ions by 30%~50%, thereby reducing the bombardment damage of high-energy hydrogen ions to the alumina layer, and can also reduce the interface state defect density to 5×10 10 cm -2 eV -1 the following.

[0030] Furthermore, in traditional plasma nitriding processes using only ammonia as the process gas, only an aluminum oxynitride layer is formed, and its surface is rough with poor adhesion to the antireflective layer. This application, however, uses a process gas including silane and ammonia to perform plasma nitriding on the alumina layer, transforming it into an aluminum oxynitride layer while simultaneously forming a silicon nitride layer on the surface of the aluminum oxynitride layer away from the silicon substrate. This enhances interfacial adhesion, improves the bonding between the aluminum oxynitride layer and the antireflective layer, and increases the open-circuit voltage of the photovoltaic cell. At the same time, the silicon nitride layer also protects the aluminum oxynitride layer during the fabrication of the antireflective layer, increasing the negative fixed charge within the aluminum oxynitride layer. This ultimately enables the photovoltaic cell to achieve higher conversion efficiency. Attached Figure Description

[0031] Figure 1 A schematic diagram of the structure for fabricating a first doped silicon layer on a first surface of a silicon substrate;

[0032] Figure 2 In order to be in Figure 1 A schematic diagram of the structure for fabricating a tunneling oxide layer and a second doped silicon layer based on the structure shown;

[0033] Figure 3 to prepare the structure shown in Figure 2 a structure schematic diagram for preparing the structure shown in

[0034] Figure 4 to form the structure shown in Figure 3 a structure schematic diagram for forming the structure shown in

[0035] Figure 5 to form the structure shown in Figure 4 a structure schematic diagram for forming the structure shown in

[0036] Figure 6 to form the structure shown in Figure 5 a structure schematic diagram for forming the structure shown in

[0037] Explanation of reference signs:

[0038] 10-silicon substrate; 20-first doped silicon layer; 30-tunneling oxide layer; 40-second doped silicon layer; 50-aluminum oxide layer; 60-aluminum nitride oxide layer; 70-silicon nitride layer; 80-first anti-reflective layer; 90-second anti-reflective layer; 100-first electrode; 110-second electrode. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0042] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0043] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] Referring to Figures 1-6 As shown in the drawings, an embodiment of the present application provides a preparation method of a photovoltaic cell, comprising the following steps:

[0045] Providing a photovoltaic cell intermediate, the photovoltaic cell intermediate comprising a silicon substrate 10 and an aluminum oxide layer 50 on at least one surface of the silicon substrate 10;

[0046] Plasma nitriding treatment is performed on the aluminum oxide layer 50 using a process gas comprising silane and ammonia, so as to convert the aluminum oxide layer 50 into an aluminum oxynitride layer 60, and form a silicon nitride layer 70 on the surface of the aluminum oxynitride layer 60 away from the silicon substrate 10.

[0047] In a conventional plasma nitriding treatment, a process gas comprising only ammonia is used for treatment, and the bombardment of high-energy hydrogen ions (H+) can cause damage to the surface of the aluminum oxide layer 50, resulting in a high interface state defect density of 1×1012cm-2eV-1. 12 cm -2 eV -1The above. In the preparation method of the above photovoltaic cell, the process gas including silane and ammonia is used to perform plasma nitridation treatment on the aluminum oxide layer 50, so that the aluminum oxide layer 50 is converted into an aluminum oxynitride layer 60. During the plasma nitridation treatment, the silane can react with high-energy hydrogen ions as follows: SiH4+H + →SiH3+H2, so that the energy of the hydrogen ions is reduced by 30% to 50%, the bombardment damage of the high-energy hydrogen ions to the aluminum oxide layer 50 is reduced, and the interface state defect density can be reduced to 5×10 10 cm -2 eV -1 The following.

[0048] Further, in the conventional plasma nitridation treatment, the process gas including only ammonia is used for treatment, only the aluminum oxynitride layer 60 is formed, and the surface is rough and has poor adhesion to the antireflection layer. However, in the present application, the process gas including silane and ammonia is used to perform plasma nitridation treatment on the aluminum oxide layer 50, so that the aluminum oxide layer 50 is converted into the aluminum oxynitride layer 60, and at the same time, a silicon nitride layer 70 is formed on the surface of the aluminum oxynitride layer 60 away from the silicon substrate 10, which can enhance the interface adhesion and improve the adhesion of the aluminum oxynitride layer 60 to the antireflection layer, thereby improving the open-circuit voltage of the photovoltaic cell. At the same time, the silicon nitride layer 70 can also protect the aluminum oxynitride layer 60 during the preparation of the antireflection layer, and improve the negative fixed charge in the aluminum oxynitride layer 60. Further, the photovoltaic cell can achieve higher conversion efficiency.

[0049] In some embodiments, the flow ratio of ammonia to silane in the process gas is (100-1000): 1.

[0050] When the flow ratio of ammonia to silane in the process gas is too low, i.e., the amount of ammonia is too small, it is easy to cause poor nitridation effect on the aluminum oxide layer 50, low nitrogen concentration in the aluminum oxynitride layer 60, and limited passivation effect. When the flow ratio of ammonia to silane in the process gas is too high, i.e., the amount of silane is too small, it is easy to cause poor effect of reducing the bombardment damage of high-energy hydrogen ions to the aluminum oxide layer 50, and limited effect of reducing the interface state defect density. Alternatively, the flow ratio of ammonia to silane in the process gas is 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1 or 1000:1, or the flow ratio of ammonia to silane in the process gas can also be within a range between any two of the above flow ratios.

[0051] In some embodiments, the flow of silane in the process gas is 0.1-1 sccm, and the flow of ammonia is 100-300 sccm.

[0052] Within the flow range of the silane and the flow range of the ammonia, the effect of the conversion of the aluminum oxide layer 50 into the aluminum oxynitride layer 60 is better, and the aluminum oxynitride layer 60 can have a proper nitrogen concentration, and the effect of reducing the bombardment damage of the high-energy hydrogen ions to the aluminum oxide layer 50 and reducing the interface state defect density is better. Optionally, the flow of the silane in the process gas is 0.1 sccm, 0.2 sccm, 0.3 sccm, 0.4 sccm, 0.5 sccm, 0.6 sccm, 0.7 sccm, 0.8 sccm, 0.9 sccm, or 1 sccm, or the flow of the silane in the process gas can also be within the range between any two of the above flows. Optionally, the flow of the ammonia in the process gas is 100 sccm, 120 sccm, 140 sccm, 160 sccm, 180 sccm, 200 sccm, 220 sccm, 240 sccm, 260 sccm, 280 sccm, or 300 sccm, or the flow of the ammonia can also be within the range between any two of the above flows.

[0053] In some embodiments, the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 1 nm.

[0054] In a conventional plasma nitridation process, a process gas including only ammonia is used for processing, and the aluminum oxide layer 50 receives greater damage from the bombardment of high-energy hydrogen ions, and the damage to the thickness of the aluminum oxide layer 50 is usually greater than or equal to 1.67 nm, that is, the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is greater than or equal to 1.67 nm. The method for preparing a photovoltaic cell provided in the present application has less damage to the aluminum oxide layer 50, and the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 can be controlled to be less than or equal to 1 nm. Optionally, the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 0.9 nm, or the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 0.8 nm, or the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 0.7 nm, or the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 0.6 nm, or the difference between the thickness of the aluminum oxide layer 50 and the thickness of the aluminum oxynitride layer 60 is less than or equal to 0.5 nm.

[0055] In some embodiments, the power of the plasma nitridation process is 200 W to 500 W.

[0056] Optionally, the power of the plasma nitridation process is 200 W, 250 W, 300 W, 350 W, 400 W, 450 W, or 500 W, or the power of the plasma nitridation process can also be within the range between any two of the above powers.

[0057] In some embodiments, the plasma nitriding treatment pressure is 500 mTorr to 1000 mTorr.

[0058] Optionally, the plasma nitriding pressure is 500 mTorr, 600 mTorr, 700 mTorr, 800 mTorr, 900 mTorr or 1000 mTorr, or the plasma nitriding pressure may be within any two of the above pressures.

[0059] In some embodiments, the plasma nitriding treatment temperature is 350°C to 450°C.

[0060] Optionally, the plasma nitriding treatment temperature is 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, or 450°C, or the plasma nitriding treatment temperature may be within any two of the above temperatures.

[0061] In some embodiments, the plasma nitriding treatment time is 1 min to 5 min.

[0062] Optionally, the plasma nitriding treatment time is 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, or 5 min, or the plasma nitriding treatment time can be within any two of the above times.

[0063] Within the range of parameters for the aforementioned plasma nitriding treatments, it is convenient to simultaneously achieve a good nitriding effect on the alumina layer 50, as well as reduce the bombardment damage of high-energy hydrogen ions to the alumina layer 50 and reduce the density of interface state defects.

[0064] In some embodiments, during plasma nitriding, the nitrogen concentration in the aluminum oxynitride layer 60 is controlled to be 5 × 10⁻⁶. 20 cm -3 ~1×10 22 cm -3 .

[0065] Optionally, during plasma nitriding, the nitrogen concentration in the alumina oxynitride layer 60 is controlled to be 5 × 10⁻⁶. 20 cm -3 8×10 20 cm -3 1×10 21 cm -3 2×10 21 cm -3 5×10 21 cm -38x10 21 cm -3 or 1x10 22 cm -3 Alternatively, the nitrogen concentration in the aluminum oxynitride layer 60 in the plasma nitridation process can also be within a range between any two concentrations mentioned above.

[0066] In some embodiments, the thickness of the silicon nitride layer 70 in the plasma nitridation process is controlled to be between 1 nm and 3 nm.

[0067] When the thickness of the silicon nitride layer 70 is too low, the silicon nitride layer 70 has limited effect on improving the adhesion of the aluminum oxynitride layer 60 and the antireflection layer and improving the open circuit voltage of the photovoltaic cell. When the thickness of the silicon nitride layer 70 is too high, the contact effect between the electrode and the doped silicon can be affected, which affects the carrier transport. Alternatively, the thickness of the silicon nitride layer 70 in the plasma nitridation process is controlled to be 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm or 3 nm, or the thickness of the silicon nitride layer 70 can also be within a range between any two thicknesses mentioned above.

[0068] In some embodiments, the method for preparing the photovoltaic cell intermediate includes the following steps:

[0069] providing a silicon substrate 10;

[0070] forming a first doped silicon layer 20 and a second doped silicon layer 40 on the opposite surfaces of the silicon substrate 10, respectively, the first doped silicon layer 20 being P-type doped, and the second doped silicon layer 40 being N-type doped;

[0071] forming an aluminum oxide layer 50 on the surface of the first doped silicon layer 20 away from the silicon substrate 10.

[0072] In some embodiments, the surface of the first doped silicon layer 20 away from the silicon substrate 10 is textured.

[0073] In some embodiments, the method for preparing the photovoltaic cell includes the following steps:

[0074] S10: providing a silicon substrate 10, the silicon substrate 10 having a first surface and a second surface arranged oppositely, cleaning and texturing the first surface of the silicon substrate 10, and preparing a first doped silicon layer 20 of P-type on the first surface;

[0075] Referring to FIG. 1, which is a structural schematic diagram of the first doped silicon layer 20 prepared on the first surface of the silicon substrate 10. Figure 1 Figure 1

[0076] ​​S20: preparing a tunneling oxide layer 30 on the second surface; preparing an N-type doped second doped silicon layer 40 on the surface of the tunneling oxide layer 30;

[0077] Referring to Figure 2 , the tunneling oxide layer 30 and the second doped silicon layer 40 are prepared on the basis of the structure shown in Figure 2 . Figure 1

[0078] S30: preparing an aluminum oxide layer 50 on the surface of the first doped silicon layer 20 away from the silicon substrate 10;

[0079] Referring to Figure 3 , the aluminum oxide layer 50 is prepared on the basis of the structure shown in Figure 3 . Figure 2

[0080] S40: performing plasma nitridation treatment on the aluminum oxide layer 50 using a process gas including silane and ammonia, so as to convert the aluminum oxide layer 50 into an aluminum oxynitride layer 60, and form a silicon nitride layer 70 on the surface of the aluminum oxynitride layer 60 away from the silicon substrate 10;

[0081] Referring to Figure 4 , the aluminum oxynitride layer 60 and the silicon nitride layer 70 are formed on the basis of the structure shown in Figure 4 . Figure 3

[0082] S50: preparing a first anti-reflection layer 80 on the surface of the silicon nitride layer 70 away from the silicon substrate 10, and preparing a second anti-reflection layer 90 on the surface of the second doped silicon layer 40 away from the silicon substrate 10;

[0083] Referring to Figure 5 , the first anti-reflection layer 80 and the second anti-reflection layer 90 are formed on the basis of the structure shown in Figure 5 . Figure 4

[0084] S60: preparing a first electrode 100 on the surface of the first anti-reflection layer 80 away from the silicon nitride layer 70, the first electrode 100 being electrically connected with the first doped silicon layer 20; preparing a second electrode 110 on the surface of the second anti-reflection layer away from the second doped silicon layer 40, the second electrode 110 being electrically connected with the second doped silicon layer 40.

[0085] Referring to Figure 6 , the first electrode 100 and the second electrode 110 are formed on the basis of the structure shown in Figure 6 . Figure 5

[0086] ​​​​​A further embodiment of the present application provides a photovoltaic cell, comprising: a silicon substrate 10, and an aluminum oxynitride layer 60 and a silicon nitride layer 70 which are stacked on a surface of the silicon substrate 10, the aluminum oxynitride layer 60 being between the silicon nitride layer 70 and the silicon substrate 10, and the silicon nitride layer 70 having a thickness of 1 nm to 3 nm.

[0087] Referring again to Figure 6 In some embodiments, the silicon substrate 10 has a first surface and a second surface which are oppositely arranged;

[0088] The first surface has a first doped silicon layer 20, the aluminum oxynitride layer 60, the silicon nitride layer 70 and a first anti-reflection layer 80 which are sequentially stacked thereon; the first doped silicon layer 20 is P-type doped; the first anti-reflection layer 80 has a first electrode 100 arranged thereon, and the first electrode 100 is electrically connected to the first doped silicon layer 20.

[0089] The second surface has a tunneling oxide layer 30, a second doped silicon layer 40 and a second anti-reflection layer 90 which are sequentially stacked thereon; the second doped silicon layer 40 is N-type doped; the second anti-reflection layer 90 has a second electrode 110 arranged thereon, and the second electrode 110 is electrically connected to the second doped silicon layer 40.

[0090] In some embodiments, the P-type doped doping element includes at least one of boron, aluminum, gallium and indium.

[0091] In some embodiments, the N-type doped doping element includes at least one of phosphorus, arsenic, antimony and nitrogen.

[0092] In some embodiments, the material of the tunneling oxide layer 30 includes at least one of silicon dioxide and silicon oxynitride.

[0093] In some embodiments, the material of the first anti-reflection layer 80 and the material of the second anti-reflection layer 90 each independently includes at least one of silicon nitride and aluminum nitride.

[0094] A further embodiment of the present application provides a photovoltaic module, comprising:

[0095] A cover plate;

[0096] At least one cell string, the cell string comprising a photovoltaic cell prepared by the method for preparing a photovoltaic cell of any one of the above, or the photovoltaic cell of any one of the above;

[0097] And a packaging layer, the packaging layer being between the cover plate and the cell string, and the cover plate being connected to the cell string through the packaging layer.

[0098] The following are specific embodiments:

[0099] Embodiment 1

[0100] A method for preparing a photovoltaic cell

[0101] (1) providing an N-type silicon substrate 10, performing standard RCA cleaning and texturing on the front surface of the silicon substrate 10, and performing boron diffusion on the front surface to prepare a P-type doped first doped silicon layer 20;

[0102] (2) removing the borosilicate glass layer on the back surface of the silicon substrate 10, depositing a 1.5 nm thick silicon dioxide tunneling oxide layer 30 on the back surface of the silicon substrate 10, depositing a 150 nm thick amorphous silicon layer on the surface of the tunneling oxide layer 30 away from the silicon substrate 10, performing phosphorus diffusion on the amorphous silicon layer and annealing at 900°C for 30 min to convert the amorphous silicon layer into an N-type doped second doped silicon layer 40;

[0103] (3) depositing a 5 nm thick aluminum oxide layer 50 on the surface of the first doped silicon layer 20 away from the silicon substrate 10, performing plasma nitridation treatment on the aluminum oxide layer 50 using silane and ammonia gas to convert the aluminum oxide layer 50 into an aluminum oxynitride layer 60, and forming a silicon nitride layer 70 on the surface of the aluminum oxynitride layer 60 away from the silicon substrate 10; the flow ratio of ammonia gas to silane is 800:1, the power is 400W, the temperature is 400°C, and the time is 2 min;

[0104] (4) preparing a 80 nm thick silicon nitride anti-reflection layer on the surface of the silicon nitride layer 70 away from the silicon substrate 10 and on the surface of the second doped silicon layer 40 away from the silicon substrate 10, respectively;

[0105] (5) preparing a first electrode 100 and a second electrode 110.

[0106] Comparative Example 1

[0107] The preparation method of the photovoltaic cell in Comparative Example 1 is basically the same as that in Example 1, the only difference is that in step (3), silane is replaced by ammonia gas with the same flow rate.

[0108] The photovoltaic cells prepared in Example 1 and Comparative Example 1 were tested, and the test results were averaged from multiple samples, as shown in Table 1:

[0109]

[0110] From the test results, it can be seen that the photovoltaic cell prepared in Example 1 has improved open circuit voltage and conversion efficiency compared to the photovoltaic cell prepared in Comparative Example 1.

[0111] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all such possible combinations.

[0112] The above-described embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the patent protection scope of the application should be subject to the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for preparing a photovoltaic cell, characterized in that, Includes the following steps: A photovoltaic cell intermediate is provided, the photovoltaic cell intermediate comprising a silicon substrate and an aluminum oxide layer located on at least one surface of the silicon substrate; The alumina layer is subjected to plasma nitriding treatment using a process gas comprising silane and ammonia, wherein the flow ratio of ammonia to silane in the process gas is (100~1000):1, so as to transform the alumina layer into an aluminum oxynitride layer and form a silicon nitride layer on the surface of the aluminum oxynitride layer away from the silicon substrate.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that, In the process gas, the flow rate of silane is 0.1 sccm to 1 sccm, and the flow rate of ammonia is 100 sccm to 300 sccm.

3. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The difference in thickness between the alumina layer and the alumina oxynitride layer is less than or equal to 1 nm.

4. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The plasma nitriding treatment satisfies at least one of the following characteristics: (1) Power is 200W~500W; (2) The pressure is 500mTorr~1000mTorr.

5. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The plasma nitriding treatment satisfies at least one of the following characteristics: (1) The temperature is 350℃~450℃; (2) The time is 1 min to 5 min.

6. The method for preparing a photovoltaic cell according to claim 1, characterized in that, The plasma nitriding treatment satisfies at least one of the following characteristics: (1) The nitrogen concentration in the alumina layer is controlled to be 5 × 10⁻⁶. 20 cm -3 ~1×10 22 cm -3 ; (2) The thickness of the silicon nitride layer is controlled to be 1nm~3nm.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The method for preparing the photovoltaic cell intermediate includes the following steps: Provide silicon substrates; A first doped silicon layer and a second doped silicon layer are formed on two opposing surfaces of the silicon substrate, respectively. The first doped silicon layer is P-type doped, and the second doped silicon layer is N-type doped. The aluminum oxide layer is formed on the surface of the first doped silicon layer away from the silicon substrate.

8. A photovoltaic cell, characterized in that, The photovoltaic cell is prepared by the method of any one of claims 1 to 7, comprising: a silicon substrate, and an aluminum oxynitride layer and a silicon nitride layer stacked on the surface of the silicon substrate, wherein the aluminum oxynitride layer is located between the silicon nitride layer and the silicon substrate, and the thickness of the silicon nitride layer is 1 nm to 3 nm.

9. The photovoltaic cell according to claim 8, characterized in that, The silicon substrate has a first surface and a second surface disposed opposite to each other; A first doped silicon layer, an aluminum oxynitride layer, a silicon nitride layer, and a first antireflection layer are sequentially stacked on the first surface; the first doped silicon layer is p-type doped; a first electrode is disposed on the first antireflection layer, and the first electrode is electrically connected to the first doped silicon layer. A tunneling oxide layer, a second doped silicon layer, and a second antireflection layer are sequentially stacked on the second surface; the doping type of the second doped silicon layer is N-type doping. A second electrode is disposed on the second antireflection layer, and the second electrode is electrically connected to the second doped silicon layer.

10. A photovoltaic module, characterized in that, include: Cover plate; At least one battery string, the battery string comprising a photovoltaic cell prepared by the method of any one of claims 1 to 7, or a photovoltaic cell prepared by any one of claims 8 to 9; as well as An encapsulation layer is located between the cover plate and the battery string, and the cover plate is connected to the battery string through the encapsulation layer.

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