A solar cell and a method of manufacturing the same, assembly and system

Abstract

This invention discloses a solar cell and its fabrication method, components, and system. The solar cell includes a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate. The passivation layer has electrode trenches that locally expose the doped layer, and the electrode trenches are provided with a back electrode. The back electrode includes a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer, and an outer metal layer sequentially stacked on the back side of the locally exposed doped layer. The seed metal silicide layer is one or more layers selected from molybdenum silicide, nickel silicide, and titanium silicide layers; the seed metal oxide thin layer is one or more layers selected from molybdenum oxide, nickel oxide, and titanium oxide thin layers; and the thickness of the seed metal oxide thin layer is no greater than 20 nm. This solar cell has a novel electrode structure, which can promote improvements in electrode structure and performance, and reduce costs. The novel electrode structure of this solar cell exhibits good current transport performance and low metal recombination loss.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell technology, specifically to a solar cell and its preparation method, components, and system. Background Technology

[0002] Solar cells, also known as photovoltaic cells, are batteries that directly convert sunlight into electrical energy. They can be classified into monocrystalline silicon, polycrystalline silicon, and amorphous silicon solar cells. Among existing photovoltaic cell technologies, crystalline silicon solar cells are relatively mature and have the widest application. However, existing crystalline silicon solar cells still have some drawbacks. For example, current industrialized crystalline silicon solar cells generally use screen-printed silver paste combined with a high-temperature sintering process to complete the metallization process and form electrodes; however, this process requires a large amount of expensive silver paste, increasing the material cost of crystalline silicon solar cells.

[0003] Therefore, to reduce the cost of solar cells, researchers are gradually improving the electrode structure of solar cells. For example, CN113629155A discloses a crystalline silicon solar cell whose grid electrode includes a first metal layer (such as titanium silicide paste) formed on a doped conductive layer, a dielectric conductive layer (such as titanium nitride paste) formed on the first metal layer, and a second metal layer (such as aluminum paste) formed on the dielectric conductive layer. This grid electrode eliminates the need for expensive silver paste, reducing raw material costs. Furthermore, the first metal layer, dielectric conductive layer, and second metal layer in this grid electrode are all conductive structures, ensuring good conductivity. In addition to conducting electricity, the dielectric conductive layer can also block metal diffusion to a certain extent, protecting the already formed first metal layer-silicon contact from being damaged by the second metal layer. It is evident that existing crystalline silicon solar cells employ a dielectric conductive layer with good conductivity to block metal diffusion. However, since the seed metal oxide layer (such as titanium oxide layer) is essentially non-conductive at room temperature and possesses insulating properties, current technology has not yet developed an electrode structure that incorporates a room-temperature insulating seed metal oxide layer (such as titanium oxide layer) within the electrode to block metal diffusion. This severely limits the selection of materials for the electrode structure, thereby restricting improvements in electrode structure and performance, as well as reductions in battery cost. Summary of the Invention

[0004] One of the objectives of this invention is to overcome the shortcomings of the prior art and provide a solar cell with a new electrode structure to promote the improvement of electrode structure and performance and the reduction of battery cost. The new electrode structure of this solar cell has good current transmission performance, good resistance to metal burn-through, and low metal recombination loss.

[0005] The second objective of this invention is to provide a method for preparing solar cells, which has a simple, stable, and reliable preparation process and is suitable for large-scale production.

[0006] The third objective of this invention is to provide a solar cell module.

[0007] The fourth objective of this invention is to provide a solar cell system.

[0008] Based on this, the present invention discloses a solar cell, comprising a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate, wherein the passivation layer has electrode trenches that locally expose the doped layer, and the electrode trenches have back electrodes; the back electrodes comprise a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the locally exposed doped layer; the seed metal silicide layer is one or more of a molybdenum silicide layer, a nickel silicide layer and a titanium silicide layer, and the seed metal oxide thin layer is one or more of a molybdenum oxide thin layer, a nickel oxide thin layer and a titanium oxide thin layer, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm.

[0009] Preferably, the outer metal layer is a copper layer, an aluminum layer, a silver layer, or an alloy layer thereof;

[0010] The hybrid conductive layer is formed by the interdiffusion of seed metal oxide and outer metal.

[0011] Preferably, the thickness of the seed metal silicide layer is less than or equal to 30 nm; the thickness of the mixed conductive layer is 10-130 nm; and the thickness of the outer metal layer is 5-20 μm.

[0012] More preferably, the outer metal layer is a copper layer, an aluminum layer, or an alloy layer thereof.

[0013] Preferably, the back side of the passivation layer is further provided with a passivation anti-scratch layer.

[0014] More preferably, the passivation anti-scratch layer is a structure formed by seed metal oxides.

[0015] More preferably, the seed metal silicide layer, the seed metal oxide thin layer, the mixed conductive layer, and the passivation and scratch-resistant layer are integrally formed.

[0016] More preferably, the thickness of the passivation and scratch-resistant layer is 10-150 nm.

[0017] Preferably, the doped layer comprises a tunneling oxide layer and a doped polycrystalline silicon layer sequentially stacked on the back side of the silicon substrate.

[0018] Preferably, the solar cell further includes a front electrode located on the front side of the silicon substrate.

[0019] The present invention also discloses a solar cell, comprising a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate, wherein the passivation layer has electrode trenches that locally expose the doped layer, and the electrode trenches have back electrodes; the back electrodes comprise a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the locally exposed doped layer; the seed metal silicide layer is an alloy layer formed from at least two of molybdenum silicide, nickel silicide and titanium silicide, the seed metal oxide thin layer is an alloy thin layer formed from at least two of molybdenum oxide, nickel oxide and titanium oxide, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm.

[0020] This invention also discloses a solar cell, comprising a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate, wherein the doped layer comprises alternately arranged P-type doped regions and N-type doped regions, with an isolation region between the P-type and N-type doped regions, and the passivation layer has a first electrode trench and a second electrode trench respectively partially exposing the P-type and N-type doped regions, the first electrode trench and the second electrode trench respectively having a positive electrode contacting the P-type doped region and a negative electrode contacting the N-type doped region; both the positive electrode and the negative electrode comprise a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the doped layer; the seed metal silicide layer is one or more layers of molybdenum silicide layer, nickel silicide layer and titanium silicide layer, and the seed metal oxide thin layer is one or more layers of molybdenum oxide thin layer, nickel oxide thin layer and titanium oxide thin layer, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm.

[0021] This invention also discloses a method for preparing a solar cell, comprising the following steps:

[0022] Step S1: Prepare a doped layer on the back side of the silicon substrate;

[0023] Step S2: A passivation layer is prepared on the back side of the doped layer;

[0024] Step S3: Perform laser film opening on the passivation layer to obtain electrode trenches that locally expose the doped layer;

[0025] Step S4: Prepare seed metal on the back side of the passivation layer and the locally exposed doped layer;

[0026] Step S5: Perform a first heat treatment on the seed metal to oxidize the back side of the seed metal into a seed metal oxide, and allow the seed metal to react with the doped layer at the interface to form a seed metal silicide layer.

[0027] Step S6: Selectively prepare an outer metal on the back side of the seed metal oxide corresponding to the electrode groove, and then perform a second heat treatment to completely oxidize the seed metal into a seed metal oxide. The seed metal oxide and the outer metal diffuse into each other at the interface to form a mixed conductive layer. The seed metal oxide far away from the mixed conductive layer forms a thin seed metal oxide layer. The seed metal oxide on the back side of the passivation layer forms a passivation anti-scratch layer, and the outer metal far away from the mixed conductive layer forms an outer metal layer.

[0028] Preferably, the first and second heat treatments are carried out in an oxygen-containing atmosphere at a temperature of 700-900°C.

[0029] Preferably, before step S1, the back side of the silicon substrate is pretreated to form a planar structure on the back side of the silicon substrate.

[0030] The present invention also discloses a solar cell module, comprising a front layer, an encapsulation layer, a cell, and a photovoltaic backsheet stacked sequentially, wherein the cell is a solar cell as described in the present invention.

[0031] The present invention also discloses a solar cell system, comprising one or more solar cell modules, wherein the solar cell module is a solar cell module as described in the present invention.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] In the solar cell of the present invention, the back electrode comprises a four-layer structure consisting of a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer, and an outer metal layer stacked sequentially. This is a novel electrode structure. (1) In this novel electrode structure, the seed metal silicide layer, the mixed conductive layer, and the outer metal layer are all conductive layers, providing good conductivity. Furthermore, the seed metal silicide layer has good electrical contact capability with the doped layer, which can reduce the contact resistivity. (2) The seed metal silicide layer near the doped layer and the mixed conductive layer near the outer metal layer can also separate the doped layer from the outer metal layer to prevent the outer metal layer from burning through the doped layer and contaminating the silicon substrate during heat treatment, thus reducing metal recombination loss. (3) Since the seed metal oxide thin layer is one or more layers of molybdenum oxide thin layer, nickel oxide thin layer, and titanium oxide thin layer stacked together, it has a higher conductivity than the seed metal oxide thin layer. The seed metal oxide thin layer is a room temperature insulating layer with better metal burn-through resistance. The seed metal oxide thin layer with insulating properties at room temperature is placed between the seed metal silicide layer and the mixed conductive layer. Together with the seed metal silicide layer and the mixed conductive layer, it can greatly improve the separation effect between the doped layer and the outer metal layer and further reduce metal recombination loss. (4) Moreover, the study found that when the thickness of the seed metal oxide thin layer between the seed metal silicide layer and the mixed conductive layer is thin (i.e. less than or equal to 20 nm), it can still perform normal current transmission performance and will not affect the current transmission effect of the battery.

[0034] (5) In addition, the seed metal silicide layer of the back electrode is one or more of molybdenum silicide layer, nickel silicide layer and titanium silicide layer, and the seed metal oxide thin layer is one or more of molybdenum oxide thin layer, nickel oxide thin layer and titanium oxide thin layer, none of which contain expensive silver, thus reducing the raw material cost of the electrode.

[0035] In summary, this invention places the back electrode of the above four-layer structure on the doped layer, which not only does not affect the current transmission, but also significantly improves its resistance to metal burn-through, greatly reduces metal recombination loss, and reduces electrode cost; it also provides a new idea for electrode structure setting, that is, to place a room temperature insulating layer, such as a seed metal oxide thin layer, on the electrode structure to improve electrode performance and reduce cost. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a solar cell in Example 1.

[0037] Figure 2 This is a schematic diagram of the structure of a solar cell after step 1 in the preparation method of an example 1.

[0038] Figure 3This is a schematic diagram of the structure of a solar cell after step 2 in the preparation method of an example 1.

[0039] Figure 4 This is a schematic diagram of the structure of a solar cell after step 3 in the preparation method of an example 1.

[0040] Figure 5 This is a schematic diagram of the structure after step 4 in the fabrication method of a solar cell in Example 1.

[0041] Figure 6 This is a schematic diagram of the structure after step 5 in the preparation method of a solar cell in Example 1.

[0042] Figure 7 This is a schematic diagram of the structure after step 6 in the preparation method of a solar cell in Example 1.

[0043] Figure 8 This is a schematic diagram of the structure of a solar cell in Example 2.

[0044] Reference numerals: 1. Silicon substrate; 2. Doped layer; 21. P-type doped region; 22. Isolation region; 23. N-type doped region; 3. Passivation layer; 4. Passivation anti-scratch layer; 5. Seed metal silicide layer; 6. Seed metal oxide thin layer; 7. Mixed conductive layer; 8. Outer metal layer; 9. Electrode trench; 10. Seed metal; 11. Seed metal oxide. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1

[0047] One embodiment of the solar cell, see [link / reference] Figure 1 The battery includes a silicon substrate 1, a doped layer 2, and a passivation layer 3 sequentially stacked on the back side of the silicon substrate 1. In practical applications, the doped layer 2 and passivation layer 3 are sequentially stacked on the back side of the silicon substrate 1, and a back electrode is disposed on the back side of the silicon substrate 1. Alternatively, depending on the design requirements of different battery structures, the doped layer 2 and passivation layer 3 can also be sequentially stacked on the front side of the silicon substrate 1, and a front electrode can be disposed on the front side of the silicon substrate 1. The structural design of the back electrode is described in detail below. Of course, the following structure of the back electrode can also be applied to the front electrode.

[0048] Among them, the passivation layer 3 located on the back side of the silicon substrate 1 has electrode trenches 9 that expose the doped layer 2 locally (e.g., Figure 5As shown, the electrode groove 9 is provided with the back electrode for transmitting current. The back electrode includes a seed metal silicide layer 5, a seed metal oxide thin layer 6, a mixed conductive layer 7, and an outer metal layer 8, which are sequentially stacked on the back of the locally exposed doped layer 2. In one example of this embodiment, the seed metal silicide layer 5 in the back electrode is one or more layers of molybdenum silicide, nickel silicide, and titanium silicide; in another example of this embodiment, the seed metal silicide layer 5 may be an alloy layer formed from at least two of molybdenum silicide, nickel silicide, and titanium silicide (such as an alloy layer formed from titanium silicide and nickel silicide). The thickness of the seed metal silicide layer 5 is less than or equal to 30 nm, more preferably 0.1-20 nm. For example, the thickness of the seed metal silicide layer 5 is 0.1 nm, 0.5 nm, 1 nm, 3 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm or 30 nm. The seed metal silicide layer 5 is a conductive layer with good conductivity, and the seed metal silicide layer 5 has good electrical contact with the doped layer 2, which can reduce the contact resistivity.

[0049] The gate line width of the outer metal layer 8 is greater than the width of the electrode trench 9; the ratio of the projected area of ​​the outer metal layer 8 on the silicon substrate 1 to the area of ​​the silicon substrate 1 is preferably greater than 1:10000. Further, the outer metal layer 8 is a copper layer, an aluminum layer, a silver layer, or an alloy layer thereof (such as a copper-aluminum alloy layer), and the thickness of the outer metal layer 8 is 5-20 μm, for example, 5 μm, 8 μm, 10 μm, 15 μm, or 20 μm. In one example of this embodiment, the seed metal oxide thin layer 6 is one or more layers of molybdenum oxide thin layer, nickel oxide thin layer, and titanium oxide thin layer stacked together; in another example of this embodiment, the seed metal oxide thin layer 6 is an alloy thin layer formed from at least two of molybdenum oxide, nickel oxide, and titanium oxide (such as an alloy thin layer formed from titanium oxide and nickel oxide). The seed metal oxide thin layer 6 has a thickness of less than or equal to 20 nm, for example, the thickness of the seed metal oxide thin layer 6 is 0.1 nm, 0.5 nm, 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, or 20 nm. The mixed conductive layer 7 is a structure formed by the interdiffusion of the seed metal oxide 11 and the outer metal. Specifically, the mixed conductive layer 7 is formed by the interdiffusion of the seed metal oxide 11 and the outer metal at the interface during a high-temperature heat treatment process such as 700-900°C. The thickness of the mixed conductive layer 7 is 10-130 nm, for example, the thickness of the mixed conductive layer 7 is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, or 130 nm.

[0050] In this embodiment of the solar cell, the back electrode includes a four-layer structure consisting of a seed metal silicide layer 5, a seed metal oxide thin layer 6, a mixed conductive layer 7, and an outer metal layer 8 stacked sequentially. This is a novel electrode structure. (1) In this novel electrode structure, the seed metal silicide layer 5, the mixed conductive layer 7, and the outer metal layer 8 are all conductive layers, providing good conductivity. The seed metal silicide layer 5 has good electrical contact capability with the doped layer 2, which can reduce the contact resistivity. (2) The seed metal silicide layer 5 near the doped layer 2 and the mixed conductive layer 7 near the outer metal layer 8 can also separate the doped layer 2 from the outer metal layer 8 to prevent the outer metal layer 8 from burning through the doped layer 2 and contaminating the silicon substrate 1 during heat treatment, thus reducing metal recombination loss. (3) The seed metal oxide thin layer 6 is composed of one or more layers of molybdenum oxide thin layer, nickel oxide thin layer, and titanium oxide thin layer, so it has a higher conductivity than the seed metal oxide thin layer. The seed metal oxide thin layer 6 is a room-temperature insulating layer with better metal burn-through resistance, consisting of a silicide layer 5 and a mixed conductive layer 7. This seed metal oxide thin layer 6, which has insulating properties at room temperature, is placed between the seed metal silicide layer 5 and the mixed conductive layer 7. Together with the seed metal silicide layer 5 and the mixed conductive layer 7, it can greatly improve the separation effect between the doped layer 2 and the outer metal layer 8, and further reduce metal recombination loss. (4) Moreover, research has found that when the thickness of the seed metal oxide thin layer 6 between the seed metal silicide layer 5 and the mixed conductive layer 7 is relatively thin (i.e., less than or equal to 20 nm), it can still perform normal current transmission performance and will not affect the current transmission effect of the battery. (5) In addition, the seed metal silicide layer 5 of the back electrode is one or more layers of molybdenum silicide layer, nickel silicide layer and titanium silicide layer, and the seed metal oxide thin layer 6 is one or more layers of molybdenum oxide thin layer, nickel oxide thin layer and titanium oxide thin layer. Neither of them contains expensive silver, so the raw material cost of the electrode can be reduced.

[0051] Therefore, the back electrode of this embodiment provides a new approach to electrode structure design, namely, setting a room-temperature insulating layer, such as the seed metal oxide thin layer 6, in the electrode structure to improve electrode performance and reduce cost. Specifically, setting the back electrode of the four-layer structure on the doped layer 2 not only does not affect current transmission, but also significantly improves its resistance to metal burn-through, greatly reduces metal recombination loss, and reduces electrode cost.

[0052] Furthermore, the outer metal layer 8 is preferably a copper layer, an aluminum layer, or an alloy layer thereof (such as a copper-aluminum alloy layer), so that the back electrode does not contain expensive silver at all, which can further reduce the raw material cost of the electrode.

[0053] The passivation layer 3 also includes a passivation and scratch-resistant layer 4 on its back side. The thickness of the passivation and scratch-resistant layer 4 is 10-150 nm, for example, 10 nm, 20 nm, 30 nm, 50 nm, 60 nm, 80 nm, 100 nm, 110 nm, 120 nm, 130 nm, or 150 nm. Adding this thin passivation and scratch-resistant layer 4 not only increases the thickness of the passivation structure and enhances the passivation and anti-reflection effect of the battery, but also protects the battery, making the back side less susceptible to scratches from mechanical equipment, effectively improving the battery's production yield and further reducing its production cost.

[0054] The passivation and scratch-resistant layer 4 can be a material layer that simultaneously provides passivation, anti-reflection, and scratch resistance. Preferably, it is a structure formed by a seed metal oxide 11, namely a molybdenum oxide layer, a nickel oxide layer, a titanium oxide layer, or an alloy oxide layer thereof (such as an alloy layer of titanium oxide and nickel oxide), more preferably a molybdenum oxide layer, a titanium oxide layer, or an alloy oxide layer thereof. This type of seed metal oxide 11 structure can adhere well to the back side of the doped layer 2, and its mechanical properties are better than conventional passivation films (such as silicon nitride films), exhibiting superior scratch resistance and significantly improving the battery production yield.

[0055] This embodiment also provides a method for preparing a solar cell as described above, comprising the following steps performed sequentially:

[0056] Step 1: Pre-process the back side of the silicon substrate 1. Preferably, the silicon substrate 1 is an N-type silicon substrate.

[0057] One example of this embodiment is that the back side of the silicon substrate 1 is pre-treated to form a planar structure on the back side of the silicon substrate 1, such as... Figure 2 As shown.

[0058] Step 2: Prepare a doped layer 2 on the back side of the planar structure of silicon substrate 1, such as... Figure 3 As shown. In order to improve the passivation contact performance of the solar cell, the doped layer 2 is preferably a tunneling oxide layer and a doped polycrystalline silicon layer (such as an n+ doped polycrystalline silicon layer) sequentially stacked on the back side of the silicon substrate 1.

[0059] Step 3: Prepare a passivation layer 3 on the back side of the doped layer 2, such as... Figure 4 As shown. The passivation layer 3 is preferably a silicon nitride layer.

[0060] Step 4: Laser-guided extrusion is performed on the passivation layer 3 on the back side of the silicon substrate 1 to remove localized areas of the passivation layer 3, thereby forming electrode trenches 9 that locally expose the doped layer 2, such as... Figure 5 As shown.

[0061] Step 5: Prepare seed metal 10 on the entire back side of passivation layer 3 and locally exposed doped layer 2, such as... Figure 6As shown. The seed metal 10 is prepared by screen printing or deposition, preferably by deposition using a PVD device.

[0062] Step 6: The seed metal 10 is subjected to a first heat treatment in an oxygen-containing atmosphere at 700-900℃, so that the seed metal 10 reacts with the doped layer 2 at the interface to form a seed metal silicide layer 5, and the back side of the seed metal 10 is oxidized to a seed metal oxide 11, such as... Figure 7 As shown. The temperature of the first heat treatment is 700℃, 730℃, 750℃, 770℃, 800℃, 830℃, 860℃ or 900℃.

[0063] Step 7: Selectively prepare an outer metal on the back side of the seed metal oxide 11 corresponding to the electrode groove 9, and then perform a second heat treatment in an oxygen-containing atmosphere at 700-900℃ (for example, the temperature of the second heat treatment is 700℃, 720℃, 750℃, 780℃, 800℃, 830℃, 850℃, 880℃, or 900℃) to completely oxidize the seed metal 10 into the seed metal oxide 11. The seed metal oxide 11 and the outer metal diffuse at the interface to form a mixed conductive layer 7, while the seed metal oxide 11 in the back electrode region away from the mixed conductive layer 7 forms a thin seed metal oxide layer 6. The seed metal oxide 11 located on the back side of the passivation layer 3 (i.e., the non-back electrode region) forms a passivation anti-scratch layer 4, and the outer metal away from the mixed conductive layer 7 forms an outer metal layer 8. Thus, by sequentially preparing the seed metal 10, performing the first heat treatment, preparing the outer metal, and performing the second heat treatment, the back electrode is obtained. Figure 1 As shown, the seed metal silicide layer 5, the seed metal oxide thin layer 6, the mixed conductive layer 7, and the passivation and scratch-resistant layer 4 are integrally formed. That is, the passivation and scratch-resistant layer 4, along with the seed metal silicide layer 5, the seed metal oxide thin layer 6, and the mixed conductive layer 7 in the back electrode, are all transformed from the seed metal 10 through the above steps. This simplifies the structure of the back electrode, greatly reduces the fabrication steps, and the fabrication method is stable and reliable, suitable for large-scale production. The outer metal is prepared by screen printing, deposition, or other methods such as vapor deposition, preferably screen printing.

[0064] This embodiment also discloses a solar cell module, including a front layer, an encapsulation layer, a cell, and a photovoltaic backsheet stacked in sequence, wherein the cell is a solar cell as described in this embodiment.

[0065] This embodiment also discloses a solar cell system, including one or more solar cell modules, wherein the solar cell module is the solar cell module described in this embodiment.

[0066] Example 2

[0067] This embodiment of a solar cell, whose structure, preparation method, components, and system are all the same as in Embodiment 1, see [link to Embodiment 1]. Figure 8 The difference between it and Example 1 is that:

[0068] In this embodiment, the silicon substrate 1 of the solar cell has no electrodes on its front side. The doped layer 2 on the back side of the silicon substrate 1 includes alternating P-type doped regions 21 and N-type doped regions 23, with an isolation region 22 between the P-type doped regions 21 and N-type doped regions 23. The passivation layer 3 has electrode trenches that partially expose the doped layer 2. Specifically, the electrode trenches include a first electrode trench that partially exposes the P-type doped region 21 and a second electrode trench that partially exposes the N-type doped region 23. The first electrode trench has a positive electrode that contacts the P-type doped region 21, while the second electrode trench has a negative electrode that contacts the N-type doped region 23. The positive electrode includes a seed metal silicide layer 5, a seed metal oxide thin layer 6, a mixed conductive layer 7, and an outer metal layer 8 that are sequentially stacked on the back side of the doped layer 2 for the P-type doped region 21. The negative electrode includes a seed metal silicide layer 5, a seed metal oxide thin layer 6, a mixed conductive layer 7, and an outer metal layer 8 that are sequentially stacked on the back side of the doped layer 2 for the N-type doped region 23. Both the positive and negative electrodes refer to the back electrode of Example 1 above, so they will not be described again.

[0069] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0070] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A solar cell, characterized in that: The device includes a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate, wherein the passivation layer has electrode trenches that locally expose the doped layer, and the electrode trenches have back electrodes; the back electrodes include a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the locally exposed doped layer; the seed metal silicide layer is one or more of molybdenum silicide layer, nickel silicide layer and titanium silicide layer, and the seed metal oxide thin layer is one or more of molybdenum oxide thin layer, nickel oxide thin layer and titanium oxide thin layer, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm; The hybrid conductive layer is formed by the interdiffusion of seed metal oxide and outer metal.

2. A solar cell according to claim 1, characterized in that, The outer metal layer is a copper layer, an aluminum layer, a silver layer, or an alloy layer thereof.

3. A solar cell according to claim 1 or 2, characterized in that, The thickness of the seed metal silicide layer is less than or equal to 30 nm; the thickness of the mixed conductive layer is 10-130 nm; and the thickness of the outer metal layer is 5-20 μm.

4. A solar cell according to claim 2, characterized in that, The outer metal layer is a copper layer, an aluminum layer, or an alloy layer thereof.

5. A solar cell according to claim 1, characterized in that, The passivation layer is also provided with a passivation anti-scratch layer on the back side.

6. A solar cell according to claim 5, characterized in that, The passivation and scratch-resistant layer is a structure formed by seed metal oxides.

7. A solar cell according to claim 5 or 6, characterized in that, The seed metal silicide layer, seed metal oxide thin layer, mixed conductive layer and passivation anti-scratch layer are integrally formed.

8. A solar cell according to claim 5 or 6, characterized in that, The thickness of the passivation and scratch-resistant layer is 10-150 nm.

9. A solar cell according to claim 1, characterized in that, The doped layer includes a tunneling oxide layer and a doped polycrystalline silicon layer sequentially stacked on the back side of the silicon substrate.

10. A solar cell according to claim 1, characterized in that, It also includes the front electrode located on the front side of the silicon substrate.

11. A solar cell, characterized in that: The device includes a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate, wherein the passivation layer has electrode trenches that locally expose the doped layer, and the electrode trenches have back electrodes; the back electrodes include a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the locally exposed doped layer; the seed metal silicide layer is an alloy layer formed from at least two of molybdenum silicide, nickel silicide and titanium silicide, the seed metal oxide thin layer is an alloy thin layer formed from at least two of molybdenum oxide, nickel oxide and titanium oxide, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm; The hybrid conductive layer is formed by the interdiffusion of seed metal oxide and outer metal.

12. A solar cell, characterized in that: The device includes a silicon substrate, a doped layer and a passivation layer sequentially stacked on the back side of the silicon substrate. The doped layer includes alternating P-type doped regions and N-type doped regions, with an isolation region between the P-type and N-type doped regions. The passivation layer has a first electrode trench and a second electrode trench that partially expose the P-type and N-type doped regions, respectively. The first electrode trench and the second electrode trench are respectively provided with a positive electrode contacting the P-type doped region and a negative electrode contacting the N-type doped region. Both the positive and negative electrodes include a seed metal silicide layer, a seed metal oxide thin layer, a mixed conductive layer and an outer metal layer sequentially stacked on the back side of the doped layer. The seed metal silicide layer is one or more layers of molybdenum silicide layer, nickel silicide layer and titanium silicide layer, and the seed metal oxide thin layer is one or more layers of molybdenum oxide thin layer, nickel oxide thin layer and titanium oxide thin layer, and the thickness of the seed metal oxide thin layer is less than or equal to 20 nm. The hybrid conductive layer is formed by the interdiffusion of seed metal oxide and outer metal.

13. A method for preparing a solar cell, characterized in that, Includes the following steps: Step S1: Prepare a doped layer on the back side of the silicon substrate; Step S2: A passivation layer is prepared on the back side of the doped layer; Step S3: Perform laser film opening on the passivation layer to obtain electrode trenches that locally expose the doped layer; Step S4: Prepare seed metal on the back side of the passivation layer and the locally exposed doped layer; Step S5: Perform a first heat treatment on the seed metal to oxidize the back side of the seed metal into a seed metal oxide, and allow the seed metal to react with the doped layer at the interface to form a seed metal silicide layer. Step S6: Selectively prepare an outer metal on the back side of the seed metal oxide corresponding to the electrode groove, and then perform a second heat treatment to completely oxidize the seed metal into a seed metal oxide. The seed metal oxide and the outer metal diffuse into each other at the interface to form a mixed conductive layer. The seed metal oxide far away from the mixed conductive layer forms a thin seed metal oxide layer. The seed metal oxide on the back side of the passivation layer forms a passivation anti-scratch layer, and the outer metal far away from the mixed conductive layer forms an outer metal layer.

14. The method for preparing a solar cell according to claim 13, characterized in that, The first and second heat treatments are carried out in an oxygen-containing atmosphere at a temperature of 700-900℃.

15. A method for preparing a solar cell according to claim 13, characterized in that, Before step S1, the method further includes a step of pre-treating the back side of the silicon substrate to form a planar structure on the back side of the silicon substrate.

16. A solar cell module, comprising a front layer, an encapsulation layer, cells, and a photovoltaic backsheet stacked sequentially, characterized in that, The battery is a solar cell as described in any one of claims 1-12.

17. A solar cell system comprising one or more solar cell modules, characterized in that: The solar cell module is a solar cell module as described in claim 16.

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