Passivation contact solar cell and preparation method thereof

Abstract

The invention discloses a passivation contact solar cell and a preparation method thereof, and relates to the technical field of solar cell manufacturing. According to the specific implementation of the method, a silicon substrate, an emitting electrode, a passivation layer, a plurality of metal fine grids, a metal main grid and an anti-reflection layer are included, wherein the emitting electrode and the passivation layer are arranged on the first main surface of the silicon substrate in a stacked mode from inside to outside; the metal fine grids are arranged on the passivation layer at intervals; the metal main grid is arranged on the outer side of the passivation layer and electrically connected with the metal fine grids; wherein the metal fine grid is embedded in the passivation layer and is electrically connected with the emitter; the anti-reflection layer covers the area, not occupied by the metal main grid, in the passivation layer. According to the embodiment of the invention, the metal fine grid and the metal main grid are arranged in a layered manner, so that the metal fine grid only needs to be embedded in the passivation layer and does not need to penetrate through an anti-reflection layer with relatively high hardness. Moreover, the metal fine grid is completely covered by the anti-reflection layer, so that the corrosion resistance of the metal fine grid is higher, and the reliability of the battery is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell manufacturing, and in particular to a passivated contact solar cell and a preparation method thereof. Background Art

[0002] In the existing passivated contact solar cell structure, in order to maximize the photoelectric conversion efficiency, a passivation layer and an anti-reflection layer are usually prepared on the outside of the emitter to reduce the reflectivity by using the transmittance and thickness of different materials. However, the passivation layer and the anti-reflection layer of the existing passivated contact solar cell are realized by a continuous coating process, and the metal electrode is printed and sintered after the passivation layer and the anti-reflection layer are prepared. In order to achieve the metal electrode penetrating the passivation layer and the anti-reflection layer being electrically connected to the emitter, a very high sintering temperature is required to allow the metal paste to penetrate the anti-reflection layer with a higher hardness. Summary of the invention

[0003] In view of this, the embodiments of the present invention provide a passivated contact solar cell and a method for preparing the same, wherein the metal fine grid and the metal main grid are arranged in layers, so that the metal fine grid only needs to be embedded in the passivation layer, and the current can be smoothly led from the emitter to the metal main grid arranged outside the passivation layer without penetrating the anti-reflection layer with higher hardness. Moreover, the metal fine grid is completely covered by the anti-reflection layer, so that the metal fine grid has stronger corrosion resistance, which greatly improves the reliability of the battery.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a passivated contact solar cell, comprising: a silicon substrate, an emitter and a passivation layer stacked from the inside to the outside on a first main surface of the silicon substrate, a plurality of metal fine grids spaced apart on the passivation layer, a metal main grid arranged outside the passivation layer and electrically connected to the plurality of metal fine grids, and an anti-reflection layer located outside the passivation layer; wherein the metal fine grid is embedded in the passivation layer and electrically connected to the emitter; and the anti-reflection layer covers the area of ​​the passivation layer not occupied by the metal main grid.

[0006] Optionally, the surface roughness of the metal fine grid is smaller than the surface roughness of the metal main grid.

[0007] Optionally, the surface roughness of the metal fine grid is 0.1 μm to 0.8 μm; and / or the surface roughness of the metal main grid is 1.5 μm to 2.2 μm.

[0008] Optionally, the metal fine grid is prepared by high-temperature metal slurry at a preparation temperature of 600°C to 1000°C; and / or, the metal main grid is prepared by low-temperature metal slurry at a preparation temperature of 160°C to 500°C.

[0009] Optionally, the passivation layer is made of at least one of the following materials: aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride; and / or the anti-reflection layer includes magnesium fluoride and / or lithium fluoride; and / or the thickness of the anti-reflection layer is 10 nm to 200 nm.

[0010] Optionally, it also includes: a tunneling oxide layer, a doped polysilicon layer, and a passivation anti-reflection layer stacked on the second main surface of the silicon substrate; wherein the doping type of the doping element in the doped polysilicon layer is opposite to the doping type of the doping element in the emitter.

[0011] Optionally, the thickness of the tunneling oxide layer is 0.5 nm to 3 nm; and / or the thickness of the doped polysilicon layer is 10 nm to 200 nm; and / or the passivation anti-reflection layer includes at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, and aluminum oxynitride.

[0012] In a second aspect, the present invention provides a method for preparing a passivated contact solar cell, comprising:

[0013] Step 1, preparing an emitter and a passivation layer on a first main surface of a silicon substrate from inside to outside in sequence;

[0014] Step 2, printing a first metal paste on the passivation layer at intervals, and sintering to prepare a plurality of metal fine grids, so that the metal fine grids penetrate the passivation layer and are electrically connected to the emitter;

[0015] Step 3, printing a second metal paste intersecting with the plurality of metal fine grids on the passivation layer, and drying to obtain a metal main grid, so that the metal main grid is electrically connected to the plurality of metal fine grids;

[0016] Step 4: preparing an anti-reflection layer on the passivation layer except for the metal main grid.

[0017] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects: by arranging the metal fine grid and the metal main grid in layers, the metal fine grid only needs to be embedded in the passivation layer, and the current can be smoothly led from the emitter to the metal main grid arranged outside the passivation layer without penetrating the anti-reflection layer with higher hardness. Moreover, the metal fine grid is completely covered by the anti-reflection layer, so that the corrosion resistance of the metal fine grid is stronger, which greatly improves the reliability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to better understand the present invention and do not constitute an improper limitation of the present invention.

[0019] Figure 1is a schematic diagram of the overall structure of a passivated contact solar cell according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the overall structure of another passivated contact solar cell according to an embodiment of the present invention;

[0021] Figure 3 It is a schematic diagram of the overall structure of a passivated contact solar cell in the prior art;

[0022] Figure 4 It is a schematic diagram of the main process of a method for preparing a passivated contact solar cell according to an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of a cross-sectional structure of a silicon substrate obtained after step S401 according to an embodiment of the present invention;

[0024] Figure 6 is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S402 according to an embodiment of the present invention;

[0025] Figure 7 is a schematic diagram of the cross-sectional structure of the silicon substrate in the first direction obtained after step S403 according to an embodiment of the present invention;

[0026] Figure 8 is a schematic diagram of the cross-sectional structure of the silicon substrate in the second direction obtained after step S403 according to an embodiment of the present invention;

[0027] Fig. 9 is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S404 according to an embodiment of the present invention;

[0028] Fig.10 is a schematic diagram of the main process of another method for preparing a passivated contact solar cell according to an embodiment of the present invention;

[0029] Fig.11 It is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S1002 according to an embodiment of the present invention.

[0030] The reference numerals are as follows:

[0031] 1-silicon substrate; 2-emitter; 3-passivation layer; 4-metal fine gate; 5-metal main gate; 6-anti-reflection layer; 7-tunneling oxide layer; 8-doped polysilicon layer; 9-passivation anti-reflection layer; 10-metal electrode. DETAILED DESCRIPTION

[0032] A solar cell is a photoelectric semiconductor sheet that uses sunlight to generate electricity directly. It is also called a "solar chip" or "photovoltaic cell". As long as it is illuminated by light that meets certain illumination conditions, it can instantly output voltage and generate current in the presence of a circuit. In physics, it is called solar photovoltaic (PV), or photovoltaic for short. In order to conveniently and clearly describe the method for preparing a solar cell and the solar cell of the present invention, the following exemplary embodiments of the present invention are described in conjunction with the accompanying drawings, which include various details of the embodiments of the present invention to facilitate understanding, and they should be considered as merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0033] Figure 1 and Figure 2 FIG. 1 shows a schematic diagram of the overall structure of a passivated contact solar cell provided by an embodiment of the present invention. Figure 1 and Figure 2 As shown, the passivated contact solar cell provided by the present invention includes: a silicon substrate 1, an emitter 2 and a passivation layer 3 stacked from the inside to the outside on the first main surface of the silicon substrate 1, a plurality of metal fine grids 4 spaced apart on the passivation layer 3, a metal main grid 5 arranged on the outside of the passivation layer 3 and electrically connected to the plurality of metal fine grids 4, and an anti-reflection layer 6 located on the outside of the passivation layer 3; wherein the metal fine grid 4 is embedded in the passivation layer 3 and electrically connected to the emitter 2; the anti-reflection layer 6 covers the area of ​​the passivation layer 3 not occupied by the metal main grid 5.

[0034] In order to clearly see the positional relationship between the metal fine grid 4, the metal main grid 5 and the anti-reflection layer 6, Figure 1 and Figure 2 The difference lies in whether the anti-reflection layer 6 is provided. Figure 1 and Figure 2 It can be seen that the metal fine gate 4 in the embodiment of the present invention penetrates the lower end of the passivation layer 3 and is connected to the emitter, and the upper end is higher than the upper surface of the passivation layer 3 to form a protrusion. The metal main gate 5 is arranged outside the passivation layer 3 and is not embedded in the passivation layer 3. While connecting with the metal fine gate 4, the anti-reflection layer 6 is used to cover the metal fine gate 4 and the area on the passivation layer 3 not occupied by the metal main gate 5.

[0035] In order to contrast with the structure of the prior art, Figure 3 As a schematic diagram of the overall structure of the passivated contact solar cell of the prior art, in the prior art, the passivation anti-reflection layer 9 arranged on the outside of the emitter on the front side of the silicon substrate is the same as the passivation anti-reflection layer 9 on the outside of the doped polysilicon layer 8 on the back side of the silicon substrate, both of which are stacked passivation layers and anti-reflection layers. Figure 2The passivation layer 3 and the anti-reflection layer 6 in the present application are replaced by a whole (passivation anti-reflection layer). Figure 3 It can be seen that in the prior art, the metal fine grid 4 and the metal main grid 5 are both arranged outside the passivation anti-reflection layer 9, and need to penetrate the passivation anti-reflection layer 9 to achieve electrical connection with the emitter 2. Since the anti-reflection layer material in the passivation anti-reflection layer 9 has a high hardness, in order to achieve the penetration of the metal fine grid 4 and the metal main grid 5, a high sintering temperature and a complex optimization process are required to prepare the solar cell structure of the prior art. In the present application, the metal fine grid 4 and the metal main grid 5 are respectively arranged inside the passivation layer 3 and the anti-reflection layer 6. Since the material of the passivation layer 3 is usually lower in hardness than the anti-reflection layer 6, in the embodiment of the present invention, the metal fine grid 4 is very easy to penetrate the passivation layer 3 and electrically connect to the emitter 2 during the sintering process, thereby greatly reducing the temperature requirement of the sintering process.

[0036] Moreover, in the prior art, the tops of the metal fine grid 4 and the metal main grid 5 are exposed outside the passivation anti-reflection layer 9, which is more prone to corrosion, thereby affecting the service life of the solar cell. In the embodiment of the present invention, the top of the metal fine grid 4 is covered by the anti-reflection layer 6, and only the metal main grid 5 is exposed. Therefore, compared with the structure of the prior art, the passivation contact solar cell provided by the present invention has better durability.

[0037] In an optional embodiment, the metal fine grid 4 and the metal main grid 5 are arranged crosswise, preferably vertically, so that the metal main grid 5 can be used to conduct the current in the plurality of metal fine grids 4. Figure 1 As shown, in order to improve the efficiency of current extraction, the metal main grid 5 can also be set to multiple strips, and the multiple strips are arranged at intervals to achieve synchronous current extraction.

[0038] In the embodiment of the present invention, not only the metal fine grid 4 and the metal main grid 5 are arranged in layers, but more importantly, the metal fine grid 4 and the metal main grid 5 are prepared with different metal slurries and have different surface roughness. Specifically, the surface roughness of the metal fine grid 4 provided by the present invention is less than the surface roughness of the metal main grid 5. It should be noted that surface roughness refers to the unevenness of the small spacing and tiny peaks and valleys on the processed surface. The difference in surface roughness affects the microstructure and performance of the metal electrode. Generally speaking, the smaller the surface roughness, the smoother the surface, the larger the effective contact area between the mating surfaces, the slower the wear, the stronger the corrosion resistance and the better the sealing. On the contrary, the larger the surface roughness, the rougher the surface, the lower the structural density and the better the adhesion. In the embodiment of the present invention, the surface roughness of the formed metal fine grid 4 is small, which can ensure the density and corrosion resistance of the metal fine grid 4 structure, so as to ensure that the anti-reflection layer 6 is completely covered on the surface of the metal fine grid 4, while increasing the contact area with the emitter 2, reducing the contact resistance, and increasing the derived current. The formed metal main grid 5 has a relatively large surface roughness, and a conductive channel can be formed inside the metal main grid 5, thereby improving the efficiency of current extraction and facilitating the subsequent welding process. Specifically, in an optional embodiment, the surface roughness of the metal fine grid 4 can be 0.1 μm to 0.8 μm, such as 0.1 μm, 0.3 μm, 0.5 μm, 0.7 μm, 0.8 μm, etc.; and the surface roughness of the metal main grid 5 can be 1.5 μm to 2.2 μm, such as 1.5 μm, 1.7 μm, 2.0 μm, 2.1 μm, 2.2 μm, etc.

[0039] As for the preparation material, in an optional embodiment, the metal fine grid 4 is prepared by high-temperature metal slurry, and the preparation temperature is 600℃~1000℃, such as 600℃, 700℃, 800℃, 900℃, 1000℃, etc.; the metal main grid 5 is prepared by low-temperature metal slurry, and the preparation temperature is 160℃~500℃, such as 160℃, 220℃, 300℃, 400℃, 500℃, etc. It can be understood that the surface roughness of the metal electrode prepared by different metal slurries is naturally different. Specifically, the high-temperature metal slurry is usually sintered at a higher temperature, which helps to form a smoother and denser metal electrode, so the surface roughness of the corresponding metal fine grid 4 will be lower. Low-temperature metal slurry does not require a sintering process, but is dried and solidified at a lower temperature. Since the metal particles are not fully melted and rearranged, large particles will exist, thereby forming a metal main grid 5 with a larger surface roughness.

[0040] It can be seen that in the embodiment of the present invention, by using different materials to prepare the metal fine grid 4 and the metal main grid 5, the metal fine grid 4 and the metal main grid 5 with different surface roughness are obtained, and the advantages of different surface roughness are used to perform layered arrangement, which reduces the process requirements and improves the reliability of the passivated contact solar cell.

[0041] As for the materials of the passivation layer 3 and the anti-reflection layer 6, in an optional embodiment, the passivation layer 3 is made of at least one of the following materials: aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride; and the anti-reflection layer 6 includes magnesium fluoride and / or lithium fluoride. It is worth mentioning that it is precisely because the magnesium fluoride and / or lithium fluoride in the anti-reflection layer 6 is relatively hard that the hardness of the anti-reflection layer 6 is significantly higher than that of the passivation layer 3.

[0042] In a further optional embodiment, the thickness of the anti-reflection layer 6 may be 10 nm to 200 nm, for example, 10 nm, 80 nm, 120 nm, 150 nm, 200 nm, etc. The anti-reflection layer 6 is mainly intended to reduce light reflection. If the thickness is too small, the anti-reflection effect may be poor. If the thickness is too large, it may cause waste of materials. Therefore, in the embodiment of the present invention, the thickness of the anti-reflection layer 6 is set to 10 nm to 200 nm, which can ensure the anti-reflection effect without causing excessive waste of materials.

[0043] In an optional embodiment, if Figure 1 As shown, the passivated contact solar cell provided by the present invention also includes: a tunneling oxide layer 7, a doped polysilicon layer 8, and a passivation anti-reflection layer 9 stacked on the second main surface of the silicon substrate 1; wherein the doping type of the doping element in the doped polysilicon layer 8 is opposite to the doping type of the doping element in the emitter 2.

[0044] Specifically, the doping type of the doping element in the emitter 2 and the doping type of the doping element in the doped polysilicon layer 8 are generally related to the type of the silicon substrate 1. For example, when the silicon substrate 1 is an n-type silicon substrate, the emitter is a p+ emitter, and the doping element is boron, while the doped polysilicon layer is an n+ doped polysilicon layer, and the doping element is phosphorus.

[0045] In an optional embodiment, the tunneling oxide layer 7 can be silicon oxide with a thickness of 0.5 nm to 3 nm, for example, 0.5nm, 1.0nm, 1.5nm, 2.0nm, 3.0nm, etc.; and for the doped polysilicon layer 8, the thickness of the doped polysilicon layer 8 can be set to 10 nm to 200nm, for example, 10nm, 50nm, 100nm, 150nm, 200nm, etc.; in another optional embodiment, the material of the passivation anti-reflection layer 9 arranged on the back side of the silicon substrate 1 can include at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, and aluminum oxynitride.

[0046] In summary, the passivated contact solar cell provided by the embodiment of the present invention arranges the metal fine grid and the metal main grid in layers, so that the metal fine grid only needs to be embedded in the passivation layer, and the current can be smoothly led from the emitter to the metal main grid arranged outside the passivation layer without penetrating the anti-reflection layer with higher hardness. Moreover, the metal fine grid is completely covered by the anti-reflection layer, so that the corrosion resistance of the metal fine grid is stronger, which greatly improves the reliability of the battery.

[0047] In one embodiment of the present invention, Figure 4 As shown, this embodiment provides a method for preparing a passivated contact solar cell, and the preparation method may include the following steps:

[0048] Step S401, preparing an emitter 2 and a passivation layer 3 on a first main surface of a silicon substrate 1 from inside to outside in sequence;

[0049] Step S402, printing a first metal paste on the passivation layer 3 at intervals, and sintering to prepare a plurality of metal fine gates 4, so that the metal fine gates 4 penetrate the passivation layer 3 and are electrically connected to the emitter 2;

[0050] Step S403, printing a second metal paste intersecting the plurality of metal fine grids 4 on the passivation layer 3, and drying to obtain a metal main grid 5, so that the metal main grid 5 is electrically connected to the plurality of metal fine grids 4;

[0051] Step S404 , preparing an anti-reflection layer 6 on the passivation layer 3 except for the metal main gate 5 .

[0052] For example, by Figures 5 to 9 The cross-sectional structures of the silicon substrate prepared in the above steps S401 to S404 are described respectively. Figure 5 is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S401, Figure 6 is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S402, Figure 7 and Figure 8 is a schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S403 in different directions, Fig. 9Schematic diagram of the cross-sectional structure of the silicon substrate obtained after step S404. Specifically, in order to clearly illustrate the positional relationship between the passivation layer 3, the metal fine gate 4, the metal main gate 5 and the anti-reflection layer 6, Figures 5 to 7 The cross section is obtained by cutting in the direction in which the metal main grid 5 extends. Figure 8 and Fig. 9 It is obtained by cutting along the extending direction of the metal fine grid 4 as the cross-sectional direction.

[0053] From the above Figures 5 to 9 It can be seen that compared with the process of first depositing the passivation layer and the anti-reflection layer, and then printing the metal fine grid and the metal main grid and sintering them in the prior art, the embodiment of the present invention only needs to sinter the first metal slurry to obtain the metal fine grid 4, and the sintering process only needs to penetrate the passivation layer 3 with very low hardness. Then, on the basis of preparing the metal main grid 5, the anti-reflection layer 6 is prepared, avoiding the penetration process of the anti-reflection layer 6 with higher hardness, greatly reducing the process difficulty.

[0054] In an optional embodiment, since the sintering process requires a relatively high temperature, the first metal slurry is a high-temperature metal slurry, and the preparation temperature is 600°C to 1000°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, etc. As for the second metal slurry, it only needs to be dried without going through a sintering process, so the second metal slurry is a low-temperature metal slurry, and the preparation temperature is 160°C to 500°C, such as 160°C, 220°C, 300°C, 400°C, 500°C, etc.

[0055] In addition, before preparing the emitter 2 in step S401, an optional embodiment may also include: performing an alkali texturing treatment on the first main surface of the silicon substrate 1 to form a velvet structure on the first main surface of the silicon substrate 1. During the cutting process of the silicon substrate 1, it is difficult to avoid causing damage to the surface of the silicon substrate 1, so as to affect the performance of subsequent solar cells. Therefore, before preparing the passivated contact solar cell, the embodiment of the present invention first treats the silicon substrate 1 itself, and eliminates the damage to the silicon substrate 1 caused by the cutting process through the texturing process, improves the surface morphology of the silicon substrate 1, and makes the prepared passivated contact solar cell have better performance.

[0056] For the preparation of the second main surface side of the silicon substrate, in an optional embodiment, as Fig.10 As shown, the above method also includes:

[0057] Step S1001, a tunneling oxide layer 7, a doped polysilicon layer 8, and a passivation anti-reflection layer 9 are sequentially formed on the second main surface of the silicon substrate 1 from the inside to the outside;

[0058] Step S1002 , printing and preparing a metal electrode 10 on the second passivation anti-reflection layer 9 .

[0059] Among them, the passivation layer 3, the anti-reflection layer 6, the tunneling oxide layer 7, the doped polysilicon layer 8 and the passivation anti-reflection layer 9 can be deposited by any one or more of the following methods: LPCVD (chemical vapor deposition method, Low Pressure ChemicalVapor Deposition), PECVD (Plasma Enhanced ChemicalVapor Deposition), PVD (Physical Vapor Deposition) and ALD (Atomic Layer Deposition).

[0060] Specifically, the cross-sectional structure of the silicon substrate prepared in step S1002 is as follows: Fig.11 As shown, Fig.11 and Figure 8 and Fig. 9 Similarly, both are obtained by cutting with the extension direction of the metal fine grid 4 as the cross-sectional direction.

[0061] In an optional embodiment, the silicon substrate structure obtained in step S1002 needs to be subjected to light injection or electrical injection treatment to obtain the final passivated contact solar cell of the embodiment of the present invention.

[0062] In summary, the method for preparing a passivated contact solar cell provided by an embodiment of the present invention arranges the metal fine grid and the metal main grid in layers, so that neither the metal fine grid nor the metal main grid needs to penetrate the anti-reflection layer with higher hardness, and at the same time, only the metal fine grid penetrates the passivation layer with lower hardness, and the current can be smoothly conducted from the emitter to the metal main grid arranged outside the passivation layer. Moreover, through the last step of preparing the anti-reflection layer, the metal fine grid can be completely covered with the anti-reflection layer, so that the metal fine grid has stronger corrosion resistance, which greatly improves the reliability of the battery.

[0063] Example 1

[0064] A passivated contact solar cell comprising:

[0065] An n-type silicon substrate, a p+ emitter and a passivation layer stacked from inside to outside on a first main surface of the silicon substrate, a plurality of metal fine grids spaced apart on the passivation layer, a metal main grid disposed outside the passivation layer and electrically connected to the plurality of metal fine grids, and an anti-reflection layer located outside the passivation layer;

[0066] A tunneling oxide layer, a doped polysilicon layer, and a passivation anti-reflection layer are stacked on the second main surface of the silicon substrate;

[0067] Wherein, the doping type of the doping element in the doped polysilicon layer is opposite to the doping type of the doping element in the emitter;

[0068] The metal fine grid is embedded in the passivation layer and is prepared using high-temperature metal slurry at a preparation temperature of 800°C with a surface roughness of 0.5μm.

[0069] The metal main grid is prepared by low-temperature metal slurry, the preparation temperature is 160°C, and the surface roughness is 2.0μm;

[0070] The anti-reflection layer covers the area of ​​the passivation layer not occupied by the metal main grid.

[0071] Comparative Example 1

[0072] The only difference from Example 1 is that the metal main grid is prepared by using high-temperature slurry, the preparation temperature is 800° C., the surface roughness is 0.5 μm, and at this time there is no conductive channel in the metal main grid.

[0073] Comparative Example 2 (Conventional Battery Structure)

[0074] A passivated contact solar cell comprising:

[0075] An n-type silicon substrate, a p+ emitter, a passivation layer and an anti-reflection layer stacked from inside to outside on a first main surface of the silicon substrate, a plurality of metal fine grids spaced apart on the anti-reflection layer, and a metal main grid;

[0076] A tunneling oxide layer, a doped polysilicon layer, and a passivation anti-reflection layer are stacked on the second main surface of the silicon substrate;

[0077] Wherein, the doping type of the doping element in the doped polysilicon layer is opposite to the doping type of the doping element in the emitter;

[0078] The metal fine grid and the metal main grid are embedded in the passivation layer and the anti-reflection layer, and are prepared using high-temperature metal slurry at a preparation temperature of 800° C. with a surface roughness of 0.5 μm.

[0079] The performance test of the passivated contact solar cells in the above embodiments and comparative examples was carried out, and the results were as follows:

[0080]

[0081] It can be seen that the short-circuit current (Jsc), fill factor (FF), and conversion efficiency (Eta) of Example 1 of the present invention are higher than those of Comparative Example 1 and Comparative Example 2, and the open-circuit voltage (Voc) is basically the same as those of Comparative Example 1 and Comparative Example 2, indicating that there is indeed a conductive channel in the metal main grid prepared by using low-temperature slurry, and the purpose of increasing the current can be achieved.

[0082] The introduction provided in the above steps is only used to help understand the structure, method and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A passivated contact solar cell, characterized in that: include: A silicon substrate (1), an emitter (2) and a passivation layer (3) stacked from inside to outside on a first main surface of the silicon substrate (1), a plurality of metal fine grids (4) arranged at intervals on the passivation layer (3), a metal main grid (5) arranged outside the passivation layer (3) and electrically connected to the plurality of metal fine grids (4), and an anti-reflection layer (6) located outside the passivation layer (3); The metal fine gate (4) is embedded in the passivation layer (3) and is electrically connected to the emitter (2); The anti-reflection layer (6) covers the area of ​​the passivation layer (3) that is not occupied by the metal main grid (5).

2. The passivated contact solar cell according to claim 1, characterized in that: The surface roughness of the metal fine grid (4) is smaller than the surface roughness of the metal main grid (5).

3. The passivated contact solar cell according to claim 1 or 2, characterized in that: The surface roughness of the metal fine grid (4) is 0.1 μm to 0.8 μm; and / or, The surface roughness of the metal main grid (5) is 1.5 μm to 2.2 μm.

4. The passivated contact solar cell according to claim 1 or 2, characterized in that: The metal fine grid (4) is prepared using high-temperature metal slurry at a preparation temperature of 600° C. to 1000° C.; and / or, The metal main grid (5) is prepared using low-temperature metal slurry, and the preparation temperature is 160° C. to 500° C.

5. The passivated contact solar cell according to claim 1, characterized in that: The passivation layer (3) is made of at least one of the following materials: Aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride; and / or, The anti-reflection layer (6) comprises magnesium fluoride and / or lithium fluoride; and / or, The thickness of the anti-reflection layer (6) is 10 nm to 200 nm.

6. The passivated contact solar cell according to claim 1, characterized in that: Also includes: A tunneling oxide layer (7), a doped polysilicon layer (8), and a passivation anti-reflection layer (9) are stacked and arranged on the second main surface of the silicon substrate (1); The doping type of the doping element in the doped polysilicon layer (8) is opposite to the doping type of the doping element in the emitter (2).

7. The passivated contact solar cell according to claim 6, characterized in that: The thickness of the tunnel oxide layer (7) is 0.5 nm to 3 nm; and / or, The thickness of the doped polysilicon layer (8) is 10 nm to 200 nm; and / or, The passivation anti-reflection layer (9) comprises at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, and aluminum oxynitride.

8. A method for preparing a passivated contact solar cell, characterized in that: include: Step 1, preparing an emitter (2) and a passivation layer (3) on a first main surface of a silicon substrate (1) from the inside to the outside in sequence; Step 2, printing a first metal paste on the passivation layer (3) at intervals, and sintering to prepare a plurality of metal fine grids (4), so that the metal fine grids (4) penetrate the passivation layer (3) and are electrically connected to the emitter (2); Step 3, printing a second metal paste intersecting the plurality of metal fine grids (4) on the passivation layer (3), and drying to obtain a metal main grid (5), so that the metal main grid (5) is electrically connected to the plurality of metal fine grids (4); Step 4: preparing an anti-reflection layer (6) on the passivation layer (3) in an area other than the metal main grid (5).

9. The preparation method according to claim 8, characterized in that: The first metal slurry is a high-temperature metal slurry, and the preparation temperature is 600° C. to 1000° C.; and / or, The second metal slurry is a low-temperature metal slurry, and the preparation temperature is 160°C~500°C.

10. The preparation method according to claim 8, characterized in that: Also includes: Step 5, preparing a tunneling oxide layer (7), a doped polysilicon layer (8), and a passivation anti-reflection layer (9) in sequence from the inside to the outside on the second main surface of the silicon substrate (1); Step 6: Printing and preparing a metal electrode (10) on the second passivation anti-reflection layer (9).

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