Solar cell and preparation method and application thereof

Abstract

The invention provides a solar cell and a preparation method and application thereof. The solar cell piece comprises a first film layer, a silicon substrate and a second film layer which are arranged in a stacked mode. In the direction from the silicon substrate to the first film layer, the first film layer comprises a first emission layer and a first electrode layer which are sequentially arranged in a stacked mode, the first emission layer is connected with the surface of the silicon substrate, and the crystallization rate of the side, close to the first electrode layer, of the first emission layer is larger than that of the side, close to the silicon substrate, of the first emission layer; and / or in the direction from the silicon substrate to the second film layer, the second film layer comprises a second emission layer and a second electrode layer which are stacked in sequence; the second emission layer is connected with the surface of the silicon substrate, and the crystallization rate of one side, close to the second electrode layer, of the second emission layer is larger than that of one side, close to the silicon substrate, of the second emission layer; the first emission layer is provided with a first doping element, the second emission layer is provided with a second doping element, the silicon substrate is provided with the first doping element or the second doping element, and the first doping element is different from the second doping element.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to solar cells and their preparation methods and applications. Background Art

[0002] Solar cells have attracted widespread attention due to their advantages such as high opening voltage, high bifaciality, good conversion efficiency and simple process. In the relevant technology, during the preparation of solar cells, the addition of doping elements will affect the crystallization quality of the film layer in the solar cell, and the film layer is prone to film cracking, which will also affect the photoelectric performance of the solar cell. Therefore, it is necessary to develop a solar cell with good structural reliability and high photoelectric conversion efficiency. Summary of the invention

[0003] In view of this, the present application provides a solar cell and a preparation method and application thereof, wherein the crystallization quality of the film layer in the solar cell is appropriate, the probability of film explosion is low, and the reliability of the overall structure is high; at the same time, each film layer in the solar cell has a strong ability to collect carriers, which can improve the photoelectric performance of the solar cell, improve the photoelectric conversion efficiency of the solar cell, and is conducive to the widespread application of the solar cell.

[0004] In a first aspect, the present application provides a solar cell, the solar cell comprising a silicon substrate, a first film layer disposed on a surface of the silicon substrate, and a second film layer disposed on a surface of the silicon substrate facing away from the first film layer;

[0005] In the direction from the silicon substrate to the first film layer, the first film layer includes a stacked first emission layer and a first electrode layer, the first emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer close to the first electrode layer is greater than the crystallization rate of the first emission layer close to the silicon substrate; and / or

[0006] Along the direction from the silicon substrate to the second film layer, the second film layer includes a second emission layer and a second electrode layer stacked, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer close to the second electrode layer is greater than the crystallization rate of the second emission layer close to the silicon substrate;

[0007] The first emission layer has a first doping element, the second emission layer has a second doping element, the silicon substrate has the first doping element or the second doping element, and the first doping element is different from the second doping element.

[0008] Optionally, along the direction from the silicon substrate to the first film layer, the first emission layer includes a first seed layer and a first emission layer stacked in sequence, the first seed layer is connected to the surface of the silicon substrate, the first emission layer is connected to the first electrode layer, the crystallization rate of the first seed layer is 0.3-0.6, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer; and / or

[0009] Along the direction from the silicon substrate to the second film layer, the second emission layer includes a second seed layer and a second emission layer stacked in sequence, the second seed layer is connected to the surface of the silicon substrate, the second emission layer is connected to the second electrode layer, the crystallization rate of the second seed layer is 0.3-0.6, and the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer.

[0010] Optionally, the crystallinity of the first emission layer is 0.4-0.7.

[0011] Optionally, a material of the first seed layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon carbide containing the first doping element, and microcrystalline silicon oxide containing the first doping element.

[0012] Optionally, the material of the first emission layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon carbide containing the first doping element, and microcrystalline silicon oxide containing the first doping element.

[0013] Optionally, the crystallization rate of the second emission layer is 0.4-0.7.

[0014] Optionally, a material of the second seed layer includes at least one of microcrystalline silicon, microcrystalline silicon oxide, microcrystalline silicon carbide, microcrystalline silicon containing the second doping element, microcrystalline silicon carbide containing the second doping element, and microcrystalline silicon oxide containing the second doping element.

[0015] Optionally, the material of the second emission layer includes at least one of microcrystalline silicon containing the second doping element, microcrystalline silicon carbide containing the second doping element, and microcrystalline silicon oxide containing the second doping element.

[0016] Optionally, when the second seed layer has the second doping element, a molar ratio of the second doping element to silicon in the second seed layer is greater than a molar ratio of the first doping element to silicon in the first seed layer.

[0017] Optionally, a molar ratio of the first doping element to the silicon element in the first emission layer is greater than a molar ratio of the first doping element to the silicon element in the first seed layer.

[0018] Optionally, a first passivation layer is further included between the silicon substrate and the first emission layer, and / or a second passivation layer is further included between the silicon substrate and the second emission layer.

[0019] Optionally, a material of the first passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide, and a material of the second passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide.

[0020] Optionally, the first film layer further includes a first transition layer arranged between the first emission layer and the first electrode layer.

[0021] Optionally, a material of the first transition layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon oxide containing the first doping element, and microcrystalline silicon carbide containing the first doping element.

[0022] Optionally, the second film layer further includes a second transition layer disposed between the second emission layer and the second electrode layer.

[0023] Optionally, the second film layer further includes a second transition layer and a buffer layer disposed between the second emission layer and the second electrode layer, and the second transition layer is disposed between the second emission layer and the buffer layer.

[0024] Optionally, a material of the second transition layer includes at least one of microcrystalline silicon containing the second doping element, microcrystalline silicon oxide containing the second doping element, and microcrystalline silicon carbide containing the second doping element.

[0025] Optionally, the second film layer further includes a buffer layer arranged between the second emission layer and the second electrode layer.

[0026] Optionally, a material of the buffer layer includes at least one of amorphous silicon containing the second doping element and amorphous silicon oxide containing the second doping element.

[0027] Optionally, when the second seed layer has the second doping element, a molar ratio of the second doping element to silicon in the second seed layer is greater than a molar ratio of the first doping element to silicon in the first seed layer.

[0028] Optionally, a molar ratio of the first doping element to the silicon element in the first emission layer is greater than a molar ratio of the first doping element to the silicon element in the first seed layer.

[0029] Optionally, the photoelectric conversion efficiency of the solar cell is greater than 25%.

[0030] The crystallization rate of the first emission layer and / or the second emission layer in the solar cell provided by the present application changes, so that the silicon substrate, the first emission layer and the first electrode and / or the silicon substrate, the second emission layer and the second electrode film layers are more compatible, which can effectively avoid the film bursting phenomenon, and the solar cell structure has good stability. At the same time, the carrier collection capacity is improved, which helps to improve the photoelectric conversion efficiency of the solar cell and is conducive to the widespread application of solar cells.

[0031] In a second aspect, the present application provides a method for preparing a solar cell, comprising:

[0032] A first film layer and a second film layer are deposited on a silicon substrate to obtain a solar cell; the solar cell comprises a silicon substrate, a first film layer arranged on a surface of the silicon substrate, and a second film layer arranged on a surface of the silicon substrate facing away from the first film layer; along the direction from the silicon substrate to the first film layer, the first film layer comprises a first emission layer and a first electrode layer stacked in sequence, the first emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer close to the first electrode layer is greater than the crystallization rate of the first emission layer close to the silicon substrate; and / or along the direction from the silicon substrate to the second film layer, the second film layer comprises a second emission layer and a second electrode layer stacked in sequence, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer close to the second electrode layer is greater than the crystallization rate of the second emission layer close to the silicon substrate; the first emission layer has a first doping element, the second emission layer has a second doping element, the silicon substrate has the first doping element or the second doping element, and the first doping element is different from the second doping element.

[0033] Optionally, carbon dioxide plasma treatment is further included before preparing the first emission layer and / or the second emission layer.

[0034] Optionally, the carbon dioxide flow rate in the carbon dioxide plasma treatment is 50 sccm-200 sccm, the carbon dioxide plasma treatment time is 5s-15s, and the carbon dioxide plasma treatment power is 66W / m 2 -200W / m 2 .

[0035] The method for preparing the solar cell provided in the present application is novel and has a simple preparation process, and can prepare solar cells with excellent comprehensive performance.

[0036] In a third aspect, the present application provides a solar cell, wherein the solar cell comprises the solar cell described in the first aspect or the solar cell manufactured by the preparation method described in the second aspect.

[0037] The solar cell provided in the present application has high photoelectric conversion efficiency and good safety in use, which is conducive to improving the application of solar cells.

[0038] In a fourth aspect, the present application provides an electrical device, wherein the electrical device comprises the solar cell described in the third aspect.

[0039] The electrical equipment provided in this application has excellent comprehensive performance, high photoelectric utilization rate and strong product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the prior art description. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0041] Figure 1 A schematic cross-sectional view of a solar cell provided in accordance with one embodiment of the present application.

[0042] Figure 2 A schematic cross-sectional view of a solar cell provided in another embodiment of the present application.

[0043] Figure 3 A schematic cross-sectional view of a solar cell provided in yet another embodiment of the present application.

[0044] Figure 4 A schematic cross-sectional view of a solar cell provided in yet another embodiment of the present application.

[0045] Figure 5 A schematic cross-sectional view of a solar cell provided in yet another embodiment of the present application.

[0046] Figure 6 A schematic cross-sectional view of a solar cell provided in yet another embodiment of the present application.

[0047] Figure 7 A schematic cross-sectional view of a solar cell provided in yet another embodiment of the present application.

[0048] Figure 8 A flow chart of the preparation of a solar cell provided in one embodiment of the present application.

[0049] Fig. 9 A flow chart of the preparation of a solar cell provided in another embodiment of the present application.

[0050] Fig.10 A flow chart of preparing a solar cell provided in yet another embodiment of the present application.

[0051] Fig.11A flow chart of preparing a solar cell provided in yet another embodiment of the present application.

[0052] Fig.12 A flow chart of preparing a solar cell provided in yet another embodiment of the present application.

[0053] Fig.13 This is a surface morphology image of the solar cell after coating provided in Example 1 of the present application.

[0054] Fig.14 This is a surface morphology image of the solar cell after coating provided in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] See also Figure 1, is a cross-sectional schematic diagram of a solar cell provided in one embodiment of the present application, wherein the solar cell 100 comprises a silicon substrate 10, a first film layer 20 disposed on a surface of the silicon substrate 10, and a second film layer 30 disposed on a surface of the silicon substrate 10 on a side away from the first film layer 20; along the direction from the silicon substrate 10 to the first film layer 20, the first film layer 20 comprises a stacked first emission layer 23' and a first electrode layer 24, the first emission layer 23' is connected to the surface of the silicon substrate 10, and the crystallization rate of the first emission layer 23' on the side close to the first electrode layer 24 is greater than that on the side close to the silicon substrate 10 The crystallization rate on one side; and / or along the direction from the silicon substrate 10 to the second film layer 30, the second film layer 30 includes a second emission layer 33' and a second electrode layer 34 stacked in sequence, the second emission layer 33' is connected to the surface of the silicon substrate 10, and the crystallization rate of the second emission layer 33' close to the second electrode layer 34 is greater than the crystallization rate of the second emission layer 33' close to the silicon substrate 10; the first emission layer 23' has a first doping element, the second emission layer 33' has a second doping element, the silicon substrate 10 has a first doping element or a second doping element, and the first doping element is different from the second doping element. The silicon substrate is a light absorption area, which can enhance the light absorption efficiency of the solar cell; in the direction from the silicon substrate to the first film layer or the second film layer, the crystallization rate of the first emission layer close to the first electrode layer is greater than the crystallization rate of the first emission layer close to the silicon substrate, and the crystallization rate of the second emission layer close to the second electrode layer is greater than the crystallization rate of the second emission layer close to the silicon substrate, which can alleviate the surge in hydrogen atoms caused by the substantial increase in the crystallization rate, reduce the film stress generated by hydrogen atoms, and reduce the occurrence of film explosion, which is beneficial to improving the structural stability, service life and photoelectric conversion efficiency of the solar cell; the first electrode layer and the second electrode layer can improve the conductivity of the solar cell and realize efficient photoelectric conversion. Therefore, the solar cell provided by the present application has good structural stability and good photoelectric conversion efficiency, which is beneficial to its use.

[0057] In the present application, the silicon substrate is a light absorption region, which can enhance the light absorption efficiency of the solar cell. In some embodiments, the material of the silicon substrate can be single crystal silicon.

[0058] In the present application, the silicon substrate and the first emission layer have a first doping element, and the second emission layer has a second doping element; one of the first doping element and the second doping element can be a boron element, and the other can be a phosphorus element. In one embodiment of the present application, the silicon substrate and the first emission layer have a first doping element, which is a first doping type; the second emission layer has a second doping element, which is a second doping type; the first doping type and the second doping type are different. Specifically, one of the first doping type and the second doping type is N-type doping, and the other is P-type doping; wherein N-type doping refers to a semiconductor material with an N-type doping type and used for electron transmission, such as phosphorus doping, and P-type doping refers to a semiconductor material with a P-type doping type and used for hole transmission, such as boron doping. In the present application, the silicon substrate is a light absorption area, which improves the light absorption rate of the solar cell, provides support and growth environment for the subsequent film layer, and forms a heterojunction with the film layer to realize the photoelectric conversion of the solar cell. The difference in the first doping element makes the silicon substrate a substrate of different types. Specifically, the silicon substrate can be, but is not limited to, an N-type silicon substrate or a P-type silicon substrate. In one embodiment of the present application, the silicon substrate may be an N-type silicon substrate, which can improve the photoelectric conversion efficiency of the solar cell. In this case, the first doping element in the silicon substrate is phosphorus. In one embodiment of the present application, the silicon substrate is an N-type silicon substrate, the first film layer is the light-receiving surface, the first doping type is N-type doping, and the first doping element is phosphorus; the second film layer is the backlight surface, the second doping type is P-type doping, and the second doping element is boron. In another embodiment of the present application, the solar cell is a P-type silicon substrate, the first film layer is the light-receiving surface, the first doping type is P-type doping, and the first doping element is boron; the second film layer is the backlight surface, the second layer doping type is N-type doping, and the second doping element is phosphorus.

[0059] In the present application, the crystallization rate can reflect the ratio of crystalline and amorphous states in the film layer. The higher the crystallization rate, the more fully the film layer is crystallized. The more crystalline components, the lower the crystallization rate, indicating that the amorphous component is higher. The crystallization rate can be measured by a Raman spectrometer. The Raman spectrum of the film is fitted by Gaussian three peaks to obtain the crystallization rate Xc of the film. The crystallization rate Xc is calculated by the following formula:

[0060]

[0061] Among them, I c For crystalline silicon, I g is the crystal silicon grain boundary, I a Amorphous silicon, I 516.4 is the peak position of crystalline silicon, I 507.4 is the peak position of the crystalline silicon grain boundary, I 485.3 is the spectral peak position of amorphous silicon.

[0062] In this application, crystalline silicon generally exists in a microcrystalline structure. Microcrystalline refers to a mixed state of amorphous and polycrystalline / single crystal, which is a mixed phase disordered material between amorphous and polycrystalline / single crystal, and the grain size is usually tens to hundreds of nanometers. Amorphous is a grain-free state, and polycrystalline / single crystal is completely composed of crystal particles separated by grain boundaries. The higher the crystallization rate, the closer the state is to polycrystalline / single crystal; the lower the crystallization rate, the closer it is to amorphous state.

[0063] See also Figure 2 , is a cross-sectional schematic diagram of a solar cell provided by another embodiment of the present application, wherein the first emission layer 23' comprises a first seed layer 22 and a first emission layer 23 which are stacked in sequence, the first seed layer 22 is connected to the surface of the silicon substrate 10, the first emission layer 23 is connected to the first electrode layer 24, the crystallization rate of the first seed layer 22 is 0.3-0.6, and the crystallization rate of the first emission layer 23 is the crystallization rate of the first seed layer 22. The first seed layer is controlled between 0.3-0.6, which can reduce the occurrence of film bursting phenomenon, and is beneficial to improving the structural stability, service life and photoelectric conversion efficiency of the solar cell; the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer, the more microcrystalline structures in the solar cell, the higher the light transmittance and carrier mobility, which can improve the carrier transmission capacity and photoelectric conversion efficiency. In some embodiments, when the hydrogen passivation process is adopted, the more crystalline structures there are, the more obvious the hydrogen passivation effect is, thereby further improving the carrier transmission capacity and photoelectric conversion efficiency.

[0064] See also Figure 3 , is a cross-sectional schematic diagram of a solar cell provided by another embodiment of the present application. Among them, a first passivation layer 21 is also included between the silicon substrate 10 and the first emission layer 23'. In an embodiment of the present application, the first passivation layer can be arranged between the first seed layer and the silicon substrate, and the first passivation layer can reduce the influence of interface defects on the battery performance and improve the stability of the solar cell.

[0065] In the present application, the first seed layer provides a stable growth condition for the subsequent film layer, ensuring the structural stability of the solar cell. In one embodiment of the present application, the first passivation layer can reduce the impact of interface defects and improve the efficiency and stability of the battery. In one embodiment of the present application, the material of the first passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide. In one embodiment of the present application, the material of the first passivation layer can be amorphous silicon. In another embodiment of the present application, the material of the first passivation layer can be silicon carbide. In one embodiment of the present application, the thickness of the first passivation layer is 7nm-10nm, and the thinner first passivation layer can increase the transmission speed of the carrier. Specifically, the thickness of the first passivation layer can be, but is not limited to, 7nm, 7.5nm, 8nm, 8.5nm, 9nm, 9.5nm or 10nm, etc. In one embodiment of the present application, the thickness of the first passivation layer can be 7nm-8.5nm. In another embodiment of the present application, the thickness of the first passivation layer can be 8nm-10nm.

[0066] In one embodiment of the present application, the crystallization rate of the first seed layer is 0.3-0.6, which can reduce the generation of impurity defects and film explosion, thereby avoiding the recombination of carriers in deep energy levels and the reduction of the number of carriers due to impurity defects, improving the open circuit voltage and short circuit current of the solar cell, and improving the photoelectric conversion efficiency of the solar cell. Specifically, the crystallization rate of the first seed layer can be but is not limited to 0.3, 0.35, 0.4, 0.45, 0.5, 0.5 or 0.6. In one embodiment of the present application, the crystallization rate of the first seed layer can be 0.3-0.56. In another embodiment of the present application, the crystallization rate of the first seed layer can be 0.5-0.6.

[0067] In one embodiment of the present application, the material of the first seed layer includes at least one of microcrystalline silicon containing a first doping element, microcrystalline silicon carbide containing a first doping element, and microcrystalline silicon oxide containing a first doping element. In one embodiment of the present application, the material of the first seed layer may be microcrystalline silicon containing a first doping element. In another embodiment of the present application, the material of the first seed layer may be microcrystalline silicon oxide containing a first doping element. In one embodiment of the present application, the thickness of the first seed layer is 3nm-5nm. Specifically, the thickness of the first seed layer may be, but is not limited to, 3nm, 3.5nm, 4nm, 4.2nm, 4.5nm, 4.8nm or 5nm, etc. In one embodiment of the present application, the thickness of the first seed layer may be 3nm-4.5nm.

[0068] In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first seed layer is 1:(20-25). Specifically, the molar ratio of the first doping element to the silicon element in the first seed layer may be, but is not limited to, 1:20, 1:21, 1:22, 1:23, 1:24 or 1:25. In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first seed layer may be 1:(20-23). ​​In another embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first seed layer may be 1:(22-25).

[0069] In the present application, the crystallization rate of the first emission layer is greater than that of the first seed layer. The higher crystallization rate in the first emission layer can improve the conductivity and carrier mobility. The lower crystallization rate of the first seed layer can reduce the impurity defects generated by subsequent coating, avoid the recombination of carriers at the deep energy level of the defects, and improve the open circuit voltage and short circuit current of the solar cell. At the same time, the higher the crystallization rate, the higher the hydrogen content, the denser the film structure, and the greater the stress generated by hydrogen atoms. The first seed layer plays a transitional role between the first passivation layer and the first emission layer, balancing the process matching degree of the first passivation layer of amorphous material and the first emission layer with high crystallization rate, alleviating the surge in hydrogen content caused by the increase in crystallization rate, increasing the stress of the film layer, and reducing the film explosion phenomenon of the solar cell. In one embodiment of the present application, the crystallization rate of the first emission layer is 0.4-0.7, which balances the optical and electrical properties of the solar cell, can improve the process matching degree of the upper and lower film layers of the first emission layer, and can improve the conductivity and carrier mobility, and improve the photoelectric conversion efficiency of the solar cell. Specifically, the crystallization rate of the first emission layer may be, but is not limited to, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65 or 0.7, etc. In one embodiment of the present application, the crystallization rate of the first emission layer may be 0.4-0.55. In another embodiment of the present application, the crystallization rate of the first emission layer may be 0.5-0.7.

[0070] In one embodiment of the present application, the material of the first emission layer includes at least one of microcrystalline silicon containing a first doping element, microcrystalline silicon carbide containing a first doping element, and microcrystalline silicon oxide containing a first doping element. In one embodiment of the present application, the material of the first emission layer can be microcrystalline silicon oxide containing a first doping element, and the microcrystalline silicon oxide has a wide band gap and a wide absorption spectrum, and silicon can absorb photons on a wider spectrum to generate more carriers. In another embodiment of the present application, the material of the first emission layer can be microcrystalline silicon containing a first doping element. In one embodiment of the present application, the thickness of the first emission layer is 15nm-20nm. Specifically, the thickness of the first emission layer can be, but is not limited to, 15nm, 16nm, 17nm, 18nm, 19nm or 20nm, etc. In one embodiment of the present application, the thickness of the first emission layer can be 15nm-18nm. In another embodiment of the present application, the thickness of the first emission layer can be 17nm-20nm.

[0071] In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first emission layer is 1:(16-19). Specifically, the molar ratio of the first doping element to the silicon element in the first emission layer may be, but is not limited to, 1:16, 1:17, 1:18 or 1:19. In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first emission layer may be 1:(16-18). In another embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first emission layer may be 1:(17-19).

[0072] In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first emission layer is greater than the molar ratio of the first doping element to the silicon element in the first seed layer. A concentration gradient of the first doping element is formed between the first emission layer and the first seed layer, which can improve the carrier mobility and make more carriers move along the direction of increasing concentration gradient (i.e., electrode direction), thereby improving the short-circuit current of the solar cell. Please refer to Figure 4, is a cross-sectional schematic diagram of a solar cell provided in another embodiment of the present application, wherein the first film layer 20 also includes a first transition layer 25 disposed between the first emission layer 23 and the first electrode layer 24. The first transition layer can increase the number of carriers and improve the photoelectric conversion efficiency. In one embodiment of the present application, the material of the first transition layer includes at least one of microcrystalline silicon containing a first doping element, microcrystalline silicon oxide containing a first doping element, and microcrystalline silicon carbide containing the first doping element. In one embodiment of the present application, the material of the first transition layer may be microcrystalline silicon containing a first doping element. In one embodiment of the present application, the thickness of the first transition layer is 1nm-2nm. Specifically, the thickness of the first transition layer may be, but is not limited to, 1nm, 1.2nm, 1.3nm, 1.5nm, 1.7nm, 1.9nm or 2nm, etc. In one embodiment of the present application, the thickness of the first transition layer may be 1nm-1.6nm. In another embodiment of the present application, the thickness of the first transition layer may be 1.4nm-2nm.

[0073] In one embodiment of the present application, the molar ratio of the first doping element of the first transition layer to the silicon element is 1:(10-16). Specifically, the molar ratio of the first doping element of the first transition layer to the silicon element may be, but is not limited to, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15 or 1:16. In one embodiment of the present application, the molar ratio of the first doping element of the first transition layer to the silicon element may be 1:(10-14). In one embodiment of the present application, the molar ratio of the first doping element of the first transition layer to the silicon element may be 1:(12-16).

[0074] In one embodiment of the present application, the molar ratio of the first doping element to the silicon element in the first seed layer, the first emission layer and the first transition layer increases successively. In this way, a concentration gradient of the first doping element in a larger range is formed in the first film layer, thereby obtaining a more efficient carrier concentration gradient, improving the gradient guidance for hole transport, improving the hole carrier collection capacity, and making it easier for carriers to be absorbed by the first electrode layer of the outer layer, thereby increasing the short-circuit current and further improving the photoelectric conversion efficiency.

[0075] See also Figure 5, is a cross-sectional schematic diagram of a solar cell provided in another embodiment of the present application, wherein the first electrode layer 24 includes a first transparent conductive layer 241 and a first metal electrode 242, and the first transparent conductive layer 241 is arranged between the first emission layer 23 and the first metal electrode 242. The first transparent conductive layer has good optical transmittance and conductivity, which can improve the light utilization rate of the solar cell and enhance the photoelectric conversion rate of the solar cell. In one embodiment of the present application, the material of the first metal electrode may be, but is not limited to, at least one of gold, silver and copper. In one embodiment of the present application, the material of the first metal electrode may be silver. In one embodiment of the present application, the first transparent conductive layer may be, but is not limited to, at least one of ITO (indium tin oxide), AZO (zinc aluminum oxide) and IZO (indium zinc oxide). In one embodiment of the present application, the first transparent conductive layer may be ITO (indium tin oxide).

[0076] In one embodiment of the present application, the thickness of the first transparent conductive layer is 90nm-110nm, so that the light utilization rate can be improved. Specifically, the thickness of the first transparent conductive layer can be but not limited to 90nm, 95nm, 100nm, 102nm, 105nm or 110nm. In one embodiment of the present application, the thickness of the first transparent conductive layer can be 90nm-108nm. In another embodiment of the present application, the thickness of the first transparent conductive layer can be 100nm-110nm.

[0077] In one embodiment of the present application, please refer to Figure 2 , wherein the second emission layer 33' comprises a second seed layer 32 and a second emission layer 33 which are stacked in sequence, the second seed layer 32 is connected to the surface of the silicon substrate 10, the second emission layer 33 is connected to the second electrode layer 34, the crystallization rate of the second seed layer 32 is 0.3-0.6, the crystallization rate of the second emission layer 33 is 0.4-0.7, and the crystallization rate of the second emission layer 33 is greater than the crystallization rate of the second seed layer 32. The crystallization rate of the second seed layer is controlled between 0.3-0.6, which can reduce the occurrence of film explosion phenomenon, and is beneficial to improving the structural stability, service life and photoelectric conversion efficiency of the solar cell; the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer, and the more microcrystalline structures in the solar cell, the better the carrier transmission capacity and photoelectric conversion efficiency. In some embodiments, when the hydrogen passivation process is adopted, the more crystal structures there are, the more obvious the hydrogen passivation effect is, thereby further improving the carrier transmission capacity and photoelectric conversion efficiency.

[0078] In one embodiment of the present application, please refer to Figure 3, wherein a second passivation layer 31 is further included between the silicon substrate 10 and the second emission layer 33'. In one embodiment of the present application, the second passivation layer can be disposed between the second seed layer and the silicon substrate, and the second passivation layer can reduce the impact of interface defects on cell performance and improve the stability of the solar cell.

[0079] In one embodiment of the present application, the material of the second passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide. In one embodiment of the present application, the material of the second passivation layer may be amorphous silicon. In another embodiment of the present application, the material of the second passivation layer may be silicon carbide. In one embodiment of the present application, the thickness of the second passivation layer is 10nm-15nm. Specifically, the thickness of the second passivation layer may be, but is not limited to, 10nm, 10.5nm, 11nm, 11.5nm, 12m, 13nm, 14nm or 15nm, etc. In one embodiment of the present application, the thickness of the second passivation layer may be 10nm-13.5nm. In another embodiment of the present application, the thickness of the second passivation layer may be 12nm-15nm.

[0080] In the present application, the second seed layer provides stable growth conditions for subsequent film layers. In one embodiment of the present application, the material of the second seed layer includes at least one of microcrystalline silicon, microcrystalline silicon oxide, microcrystalline silicon carbide, microcrystalline silicon containing a second doping element, microcrystalline silicon carbide containing a second doping element, and microcrystalline silicon oxide containing a second doping element. In one embodiment of the present application, the second seed layer is microcrystalline silicon containing a second doping element, and the second doping element is boron; the second seed layer may contain a large number of stable boron-silicon chemical bonds, which are not easily decomposed by light, avoiding carrier recombination and reducing photoelectric conversion efficiency. In another embodiment of the present application, the second seed layer may also contain silicon-hydrogen chemical bonds and boron-oxygen chemical bonds, which can avoid the crystallization of the subsequent second film layer. In another embodiment of the present application, the material of the second seed layer may be microcrystalline silicon, and the second seed layer is in an eigenstate, which can reduce the growth rate of the subsequent film layer, reduce the number of structural defects in the subsequent second film layer growth process, avoid carrier-defect recombination, and reduce the number of carriers.

[0081] In one embodiment of the present application, the crystallization rate of the second seed layer is 0.3-0.6, which can reduce the occurrence of film explosion and impurity defects, increase the number of carriers, improve the open circuit voltage and short circuit current of the solar cell, and further improve the photoelectric conversion efficiency of the solar cell. Specifically, the crystallization rate of the second seed layer may be, but is not limited to, 0.3, 0.35, 0.4, 0.45, 0.5, 0.5 or 0.6, etc. In one embodiment of the present application, the crystallization rate of the second seed layer may be 0.3-0.55. In another embodiment of the present application, the crystallization rate of the second seed layer may be 0.44-0.6. In one embodiment of the present application, the thickness of the second seed layer is 1nm-3nm. Specifically, the thickness of the second seed layer may be, but is not limited to, 1nm, 1.5nm, 2nm, 2.2nm, 2.5nm, 2.8nm or 3nm, etc. In one embodiment of the present application, the thickness of the second seed layer may be 1nm-2nm. In another embodiment of the present application, the thickness of the second seed layer may be 1.5nm-3nm.

[0082] In one embodiment of the present application, when the second seed layer has a second doping element, the molar ratio of the second doping element of the second seed layer to the silicon element is 1:(13-14), and the second seed layer has a higher molar ratio of the second doping element to the silicon element, which is beneficial to improve the stability of the boron oxygen bond in the second emission layer. Specifically, the molar ratio of the second doping element of the second seed layer to the silicon element may be, but is not limited to, 1:13, 1:13.2, 1:13.5, 1:13.6, 1:13.8, 1:13.9 or 1:14, etc. In one embodiment of the present application, the molar ratio of the second doping element of the second seed layer to the silicon element may be 1:(13-13.6). In one embodiment of the present application, the molar ratio of the second doping element of the second seed layer to the silicon element may be 1:(13.4-14).

[0083] In one embodiment of the present application, when the second seed layer has a second doping element, the molar ratio of the second doping element to the silicon element in the second seed layer is greater than the molar ratio of the first doping element to the silicon element in the first seed layer. In other words, the content of the doping element in the second seed layer is greater than the content of the doping element in the first seed layer, which is beneficial to reduce the occurrence of film explosion and improve the structural stability of the solar cell.

[0084] In one embodiment of the present application, the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer. The higher crystallization rate in the second emission layer can improve the conductivity and carrier mobility. The lower crystallization rate of the second seed layer can reduce the impurity defects generated by subsequent coating, reduce the recombination phenomenon of carriers at the deep energy level of the defects, and improve the open circuit voltage and short circuit current of the solar cell; at the same time, the second seed layer plays a transitional role in the second passivation layer and the second emission layer, balancing the process matching degree of the second passivation layer of amorphous material and the second emission layer with high crystallization rate, and reducing the film explosion phenomenon of the solar cell. In one embodiment of the present application, the crystallization rate of the second emission layer is 0.4-0.7, which can improve the photoelectric conversion efficiency of the solar cell. Specifically, the crystallization rate of the second emission layer can be, but is not limited to, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65 or 0.7, etc. In one embodiment of the present application, the crystallization rate of the second emission layer can be 0.4-0.55. In another embodiment of the present application, the crystallization rate of the second emission layer may be 0.5-0.7.

[0085] In one embodiment of the present application, the material of the second emission layer includes at least one of microcrystalline silicon containing a second doping element, microcrystalline silicon carbide containing a second doping element, and microcrystalline silicon oxide containing a second doping element. In one embodiment of the present application, the material of the second emission layer can be microcrystalline silicon containing a second doping element, which reduces the number of lattice defects, increases the number of carriers, can increase the transmission speed of carriers (holes), promotes the movement of carriers toward the electrode, and can improve the photoelectric conversion efficiency of solar cells. In one embodiment of the present application, the thickness of the second emission layer is 20nm-25nm. Specifically, the thickness of the second emission layer can be but is not limited to 20nm, 21nm, 22nm, 22.5nm, 23nm, 24nm or 25nm. In one embodiment of the present application, the thickness of the second emission layer can be 20nm-24nm. In another embodiment of the present application, the thickness of the second emission layer can be 23nm-25nm.

[0086] In one embodiment of the present application, the molar ratio of the second doping element of the second emission layer to the silicon element is 1:(200-300). Specifically, the molar ratio of the second doping element of the second emission layer to the silicon element may be, but is not limited to, 1:200, 1:220, 1:240, 1:260, 1:280 or 1:300, etc. In one embodiment of the present application, the molar ratio of the second doping element of the second emission layer to the silicon element may be 1:(200-270). In another embodiment of the present application, the molar ratio of the second doping element of the second emission layer to the silicon element may be 1:(240-300).

[0087] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the second emission layer is greater than the molar ratio of the second doping element to the silicon element in the second seed layer. A concentration gradient of the second doping element is formed between the second emission layer and the second seed layer, which can promote the collection rate of carriers, accelerate the movement of carriers, and increase the short-circuit current of the solar cell.

[0088] In one embodiment of the present application, please refer to Figure 4 , the second film layer 30 also includes a second transition layer 35 disposed between the second emission layer 33 and the second electrode layer 34. The second transition layer can improve the hole carrier collection capability and enhance the carrier transport efficiency. In one embodiment of the present application, the material of the second transition layer includes at least one of microcrystalline silicon containing a second doping element, microcrystalline silicon oxide containing a second doping element, and microcrystalline silicon carbide containing a second doping element. In one embodiment of the present application, the material of the second transition layer may be microcrystalline silicon containing a second doping element, providing a gradient guide for hole transport and improving the hole carrier collection capability. In one embodiment of the present application, the material of the second transition layer may be microcrystalline silicon oxide containing a second doping element. In one embodiment of the present application, the thickness of the second transition layer is 5nm-6nm. Specifically, the thickness of the second transition layer may be, but is not limited to, 5nm, 5.2nm, 5.4nm, 5.6nm, 5.8nm or 6nm, etc. In one embodiment of the present application, the thickness of the second transition layer may be 5nm-5.6nm. In another embodiment of the present application, the thickness of the second transition layer may be 5.2nm-6nm.

[0089] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element of the second transition layer is 1:(30-200). Specifically, the molar ratio of the second doping element to the silicon element of the second transition layer may be, but is not limited to, 1:30, 1:50, 1:80, 1:100, 1:130, 1:150, 1:180 or 1:200, etc. In one embodiment of the present application, the molar ratio of the second doping element to the silicon element of the second transition layer may be 1:(30-120). In another embodiment of the present application, the molar ratio of the second doping element to the silicon element of the second transition layer may be 1:(100-200).

[0090] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the second transition layer is greater than the molar ratio of the second doping element to the silicon element in the second emission layer. In the second film layer, due to the gradual increase in the molar ratio of the doping element to the silicon element, a concentration gradient difference of the second doping element is formed between the second transition layer and the second emission layer, which improves the gradient guidance for hole transport, improves the hole carrier collection capacity, and improves the photoelectric conversion efficiency of the solar cell.

[0091] In one embodiment of the present application, please refer to Figure 5 , the second electrode layer 34 includes a second transparent conductive layer 341 and a second metal electrode 342, and the second transparent conductive layer 341 is arranged between the second emission layer 33 and the second metal electrode 342. The second transparent conductive layer has good optical transmittance and conductivity, which can improve the light utilization rate of the solar cell and enhance the photoelectric conversion rate of the solar cell. In one embodiment of the present application, the material of the second metal electrode may be, but is not limited to, at least one of gold, silver and copper. In one embodiment of the present application, the material of the second metal electrode may be silver. In one embodiment of the present application, the second transparent conductive layer may be, but is not limited to, at least one of ITO (indium tin oxide), AZO (zinc aluminum oxide) and IZO (indium zinc oxide). In one embodiment of the present application, the second transparent conductive layer may be ITO (indium tin oxide).

[0092] See also Figure 6 , is a cross-sectional schematic diagram of a solar cell provided by another embodiment of the present application, wherein the second film layer 30 also includes a buffer layer 36 disposed between the second emission layer 33 and the second electrode layer 34. The buffer layer can improve the interface contact between the second emission layer and the second electrode layer and improve the carrier transfer efficiency. In one embodiment of the present application, the material of the buffer layer includes at least one of amorphous silicon containing a second doping element and amorphous silicon oxide containing a second doping element. In one embodiment of the present application, the material of the buffer layer can be amorphous silicon oxide containing doping elements. The interface contact between amorphous silicon oxide and the second electrode layer is better than the interface contact between amorphous silicon and the second electrode layer, thereby further improving the electrical performance of the solar cell. In one embodiment of the present application, the thickness of the buffer layer is 1nm-2nm. Specifically, the thickness of the buffer layer can be, but is not limited to, 1nm, 1.2nm, 1.4nm, 1.6nm, 1.8nm or 2nm, etc. In one embodiment of the present application, the thickness of the buffer layer can be 1nm-1.6nm. In one embodiment of the present application, the thickness of the buffer layer can be 1.4nm-2nm.

[0093] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the buffer layer is 1:(10-30). Specifically, the molar ratio of the second doping element to the silicon element in the buffer layer may be, but is not limited to, 1:10, 1:15, 1:18, 1:20, 1:25, 1:27 or 1:30, etc. In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the buffer layer may be 1:(10-20). In another embodiment of the present application, the molar ratio of the second doping element to the silicon element in the buffer layer may be 1:(15-30).

[0094] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the buffer layer is greater than the molar ratio of the second doping element to the silicon element in the second emission layer, forming a concentration gradient of the second doping element, which is beneficial to increasing the number of carriers collected in each film layer.

[0095] See also Figure 7 , is a cross-sectional schematic diagram of a solar cell provided by another embodiment of the present application, wherein the second film layer 30 further includes a second transition layer 35 and a buffer layer 36, and the buffer layer 36 is disposed between the second transition layer 35 and the second electrode layer 34. The second transition layer can improve the hole carrier collection capability and the carrier transfer efficiency, and the buffer layer can improve the interface contact between the second transition layer and the second electrode layer, improve the photoelectric conversion efficiency, and prevent the second electrode layer from damaging the second transition layer. The coexistence of the second transition layer and the buffer layer can further improve the photoelectric conversion efficiency of the solar cell and improve the structural stability of the solar cell.

[0096] In one embodiment of the present application, the molar ratio of the second doping element to the silicon element in the second emission layer, the second transition layer and the buffer layer gradually increases, so that a carrier concentration gradient is formed between the three layers, and the carriers are more easily absorbed by the outer second electrode layer, thereby increasing the short-circuit current and further improving the photoelectric conversion efficiency.

[0097] In one embodiment of the present application, the photoelectric conversion efficiency of the solar cell is greater than 25%. Specifically, the photoelectric conversion efficiency of the solar cell may be, but is not limited to, greater than 25%, greater than or equal to 25.2%, greater than or equal to 25.3%, greater than or equal to 25.4%, greater than or equal to 25.5%, greater than or equal to 25.8%, or greater than or equal to 26%, etc. In one embodiment of the present application, the photoelectric conversion efficiency of the solar cell is greater than or equal to 25.2%.

[0098] The present application also provides a method for preparing a solar cell, comprising: depositing a first film layer and a second film layer on a silicon substrate to obtain a solar cell; comprising a silicon substrate, a first film layer arranged on a surface of the silicon substrate, and a second film layer arranged on a surface of the silicon substrate facing away from the first film layer; along the direction from the silicon substrate to the first film layer, the first film layer comprises a first emission layer and a first electrode layer stacked in sequence, the first emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer on a side close to the first electrode layer is greater than the crystallization rate of the first emission layer on a side close to the silicon substrate; and / or along the direction from the silicon substrate to the second film layer, the second film layer comprises a second emission layer and a second electrode layer stacked in sequence, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer on a side close to the second electrode layer is greater than the crystallization rate of the second emission layer on a side close to the silicon substrate; the silicon substrate and the first emission layer have a first doping element, the second emission layer has a second doping element, and the first doping element is different from the second doping element.

[0099] See also Figure 8 , is a flow chart of a method for preparing a solar cell provided in one embodiment of the present application, comprising:

[0100] S101: depositing a first emission layer and a first electrode layer on the surface of the silicon substrate in sequence to obtain a first film layer, wherein the first emission layer is connected to the surface of the silicon substrate, and a crystallization rate of a side of the first emission layer close to the first electrode layer is greater than a crystallization rate of a side of the first emission layer close to the silicon substrate;

[0101] S102: A second emission layer and a second electrode layer are sequentially deposited on a surface of the silicon substrate away from the first emission layer to obtain a second film layer, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer on the side close to the second electrode layer is greater than the crystallization rate of the second emission layer on the side close to the silicon substrate, thereby obtaining a solar cell. The solar cell obtained by the preparation method provided in the present application has good structural stability and high photoelectric conversion efficiency, which is conducive to the wide application of solar cells.

[0102] In the present application, deposition includes chemical vapor deposition and physical vapor deposition. Specifically, deposition may include but is not limited to at least one of atomic layer deposition, plasma enhanced chemical vapor deposition, sputtering deposition, electron beam deposition and thermal evaporation deposition. In one embodiment of the present application, deposition is plasma enhanced chemical deposition. Specifically, depending on the power supply for generating plasma, the power supply for plasma enhanced chemical deposition may include but is not limited to at least one of very high frequency (VHF) and radio frequency (RF). In one embodiment of the present application, the power supply for plasma enhanced chemical deposition may be very high frequency (VHF), which can improve the crystallinity of the film layer, reduce film formation defects, etc. In one embodiment of the present application, the power supply for plasma enhanced chemical deposition of the first passivation layer and the second passivation layer may be radio frequency (RF).

[0103] See also Fig. 9 , is a flow chart of a method for preparing a solar cell provided in another embodiment of the present application, comprising:

[0104] S201: depositing a first seed layer, a first emission layer and a first electrode layer on the surface of the silicon substrate in sequence to obtain a first film layer, wherein the first seed layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer;

[0105] S202: A second seed layer, a second emission layer and a second electrode layer are sequentially deposited on a surface of the first seed layer away from the silicon substrate to obtain a second film layer, wherein the second seed layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer is greater than that of the second seed layer, thereby obtaining a solar cell.

[0106] In one embodiment of the present application, the deposition temperature of the first seed layer is 200°C-210°C. Specifically, the deposition temperature of the first seed layer may be, but is not limited to, 200°C, 202°C, 204°C, 206°C, 208°C or 210°C, etc. In one embodiment of the present application, the deposition temperature of the first seed layer may be 200°C-204°C. In another embodiment of the present application, the deposition temperature of the first seed layer may be 202°C-210°C. In one embodiment of the present application, the deposition pressure of the first seed layer is 2mbar-4mbar. Specifically, the deposition pressure of the first seed may be, but is not limited to, 2mbar, 2.2mbar, 2.5mbar, 2.8mbar, 3mbar, 3.5mbar or 4mbar, etc. In one embodiment of the present application, the deposition pressure of the first seed layer may be 2mbar-3.5mbar. In another embodiment of the present application, the deposition pressure of the first seed layer may be 3mbar-4mbar. In one embodiment of the present application, the deposition power of the first seed layer is 660W / m 2 -1330W / m 2 Specifically, the deposition power of the first seed layer may be, but is not limited to, 660 W / m 2 , 700W / m 2 、800W / m 2 , 900W / m 2 , 1000W / m 2 、1100W / m 2 , 1200W / m 2 or 1330W / m 2 In one embodiment of the present application, the deposition power of the first seed layer can be 660 W / m 2 -900W / m 2 In another embodiment of the present application, the deposition power of the first seed layer can be 800 W / m 2 -1330W / m 2. In one embodiment of the present application, when the first seed layer is deposited, the hydrogen flow rate is 10000sccm-12000sccm. Specifically, the hydrogen flow rate may be, but not limited to, 10000sccm, 10500sccm, 11000sccm, 11500sccm or 12000sccm, etc. In one embodiment of the present application, when the first seed layer is deposited, the hydrogen flow rate may be 10000sccm-11500sccm. In another embodiment of the present application, when the first seed layer is deposited, the hydrogen flow rate may be 11500sccm-12000sccm. In one embodiment of the present application, when the first seed layer is deposited, the silane flow rate is 20sccm-40sccm. Specifically, the silane flow rate may be, but not limited to, 20sccm, 25sccm, 30sccm, 35sccm or 40sccm, etc. In one embodiment of the present application, when the first seed layer is deposited, the silane flow rate may be 20sccm-35sccm. In another embodiment of the present application, when the first seed layer is deposited, the silane flow rate may be 25sccm-40sccm. In one embodiment of the present application, when the first seed layer is deposited, the flow rate of the phosphine hydrogen mixture is 50sccm-100sccm. In the phosphine hydrogen mixture, the flow rate of the phosphine gas is 1sccm-2ccm, and the flow rate of the hydrogen gas is 48sccm-99ccm. Specifically, the flow rate of the phosphine hydrogen mixture may be, but is not limited to, 50sccm, 60sccm, 70sccm, 80sccm, 90sccm or 100sccm, etc. In one embodiment of the present application, when the first seed layer is deposited, the flow rate of the phosphine hydrogen mixture may be 50sccm-80sccm. In another embodiment of the present application, when the first seed layer is deposited, the flow rate of the phosphine hydrogen mixture may be 65sccm-100sccm. In one embodiment of the present application, when the first seed layer is deposited, the flow doping ratio of phosphine and silane is 2%-10%. Specifically, the flow doping ratio of phosphine and silane can be, but is not limited to, 2%, 3%, 5%, 7%, 9% or 10%, etc. In one embodiment of the present application, when the first seed layer is deposited, the flow doping ratio of phosphine and silane can be 2%-5%. In another embodiment of the present application, when the first seed layer is deposited, the flow doping ratio of phosphine and silane can be 4%-10%.

[0107] In one embodiment of the present application, the deposition temperature of the first emission layer is 200°C-210°C. Specifically, the deposition temperature of the first emission layer may be, but is not limited to, 200°C, 202°C, 204°C, 206°C, 208°C or 210°C, etc. In one embodiment of the present application, the deposition temperature of the first emission layer may be 200°C-204°C. In another embodiment of the present application, the deposition temperature of the first emission layer may be 202°C-210°C. In one embodiment of the present application, the deposition pressure of the first emission layer is 2mbar-4mbar. Specifically, the deposition pressure of the first emission layer may be, but is not limited to, 2mbar, 2.2mbar, 2.5mbar, 2.8mbar, 3mbar, 3.5mbar or 4mbar, etc. In one embodiment of the present application, the deposition pressure of the first emission layer may be 2mbar-3.5mbar. In another embodiment of the present application, the deposition pressure of the first emission layer may be 3mbar-4mbar. In one embodiment of the present application, the deposition power of the first emission layer is 1330 W / m 2 -2000W / m 2 Specifically, the deposition power of the first emission layer can be, but is not limited to, 1330 W / m 2 , 1400W / m 2 、1500W / m 2 、1600W / m 2 、1700W / m 2 、1800W / m 2 、1900W / m 2 or 2000W / m 2 In one embodiment of the present application, the deposition power of the first emission layer can be 1330 W / m 2 -1600W / m 2 In another embodiment of the present application, the deposition power of the first emission layer can be 1500W / m 2 -2000W / m 2. In one embodiment of the present application, when the first emission layer is deposited, the hydrogen flow rate is 10000sccm-12000sccm. Specifically, the hydrogen flow rate may be but not limited to 10000sccm, 10500sccm, 11000sccm, 11500sccm or 12000sccm, etc. In one embodiment of the present application, when the first emission layer is deposited, the hydrogen flow rate may be 10000sccm-11500sccm. In another embodiment of the present application, when the first emission layer is deposited, the hydrogen flow rate may be 11500sccm-12000sccm. In one embodiment of the present application, when the first emission layer is deposited, the silane flow rate is 50sccm-100sccm. Specifically, the silane flow rate may be but not limited to 50sccm, 60sccm, 70sccm, 80sccm, 90sccm or 100sccm, etc. In one embodiment of the present application, when the first emission layer is deposited, the silane flow rate may be 50sccm-85sccm. In another embodiment of the present application, when the first emission layer is deposited, the silane flow rate may be 65sccm-100sccm. In one embodiment of the present application, when the first emission layer is deposited, the flow rate of the phosphine hydrogen mixture is 50sccm-100sccm. In the phosphine hydrogen mixture, the flow rate of the phosphine gas is 1sccm-2ccm, and the flow rate of the hydrogen gas is 48sccm-99ccm. Specifically, the flow rate of the phosphine hydrogen mixture may be, but is not limited to, 50sccm, 60sccm, 70sccm, 80sccm, 90sccm or 100sccm, etc. In one embodiment of the present application, when the first emission layer is deposited, the flow rate of the phosphine hydrogen mixture may be 50sccm-80sccm. In another embodiment of the present application, when the first emission layer is deposited, the flow rate of the phosphine hydrogen mixture may be 65sccm-100sccm. In one embodiment of the present application, when the first emission layer is deposited, the flow doping ratio of phosphine and silane is 2%-10%. Specifically, the flow doping ratio of phosphine and silane can be but not limited to 2%, 3%, 5%, 7%, 9% or 10%, etc. In one embodiment of the present application, when the first emission layer is deposited, the flow doping ratio of phosphine and silane can be 2%-5%. In another embodiment of the present application, when the first emission layer is deposited, the flow doping ratio of phosphine and silane can be 4%-10%.

[0108] In one embodiment of the present application, the deposition temperature of the second seed layer is 160°C-180°C. Specifically, the deposition temperature of the second seed layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C or 180°C, etc. In one embodiment of the present application, the deposition temperature of the second seed layer may be 160°C-175°C. In another embodiment of the present application, the deposition temperature of the second seed layer may be 170°C-180°C. In one embodiment of the present application, the deposition pressure of the second seed layer is 2mbar-2.5mbar. Specifically, the deposition pressure of the second seed layer may be, but is not limited to, 2mbar, 2.1mbar, 2.2mbar, 2.3mbar, 2.4mbar or 2.5mbar, etc. In one embodiment of the present application, the deposition pressure of the second seed layer may be 2mbar-2.3mbar. In another embodiment of the present application, the deposition pressure of the second seed layer may be 2.2mbar-2.5mbar. In one embodiment of the present application, the deposition power of the second seed layer is 996W / m 2 -1662W / m 2 Specifically, the deposition power of the second seed layer may be, but is not limited to, 996 W / m 2 , 1000W / m 2 、1100W / m 2 , 1200W / m 2 、1300W / m 2 , 1400W / m 2 、1500W / m 2 or 1662W / m 2 In one embodiment of the present application, the deposition power of the second seed layer can be 996 W / m 2 -1262W / m 2 In another embodiment of the present application, the deposition power of the second seed layer may be 1100 W / m 2 -1662W / m 2. In one embodiment of the present application, when the second seed layer is deposited, the hydrogen flow rate is 15000sccm-25000sccm. Specifically, the hydrogen flow rate may be, but not limited to, 15000sccm, 18000sccm, 19000sccm, 20000sccm or 25000sccm, etc. In one embodiment of the present application, when the second seed layer is deposited, the hydrogen flow rate may be 15000sccm-20500sccm. In another embodiment of the present application, when the second seed layer is deposited, the hydrogen flow rate may be 20000sccm-25000sccm. In one embodiment of the present application, when the second seed layer is deposited, the silane flow rate is 25sccm-45sccm. Specifically, the silane flow rate may be, but not limited to, 25sccm, 30sccm, 35sccm, 40sccm or 45sccm, etc. In one embodiment of the present application, when the second seed layer is deposited, the silane flow rate may be 25sccm-35sccm. In another embodiment of the present application, when the second seed layer is deposited, the silane flow rate may be 30sccm-45sccm. In one embodiment of the present application, when the second seed layer is deposited, the flow rate of the diborane hydrogen mixture is 100sccm-200sccm. In the diborane hydrogen mixture, the flow rate of the diborane gas is 2sccm-4ccm, and the flow rate of the hydrogen gas is 96sccm-198ccm. Specifically, the flow rate of the diborane hydrogen mixture may be, but is not limited to, 100sccm, 130sccm, 160sccm, 170sccm, 180sccm, 190sccm or 200sccm, etc. In one embodiment of the present application, when the second seed layer is deposited, the flow rate of the diborane hydrogen mixture may be 100sccm-180sccm. In another embodiment of the present application, when the second seed layer is deposited, the flow rate of the diborane hydrogen mixture may be 165sccm-200sccm.

[0109] In one embodiment of the present application, the deposition temperature of the second emission layer is 160°C-180°C. Specifically, the deposition temperature of the second emission layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C or 180°C, etc. In one embodiment of the present application, the deposition temperature of the second emission layer may be 160°C-170°C. In another embodiment of the present application, the deposition temperature of the second emission layer may be 165°C-180°C. In one embodiment of the present application, the deposition pressure of the second emission layer is 1.5mbar-2.2mbar. Specifically, the deposition pressure of the second emission layer may be, but is not limited to, 1.5mbar, 1.6mbar, 1.8mbar, 1.9mbar, 2mbar, 2.1mbar or 2.2mbar, etc. In one embodiment of the present application, the deposition pressure of the second emission layer may be 1.5mbar-1.9mbar. In another embodiment of the present application, the deposition pressure of the second emission layer may be 1.8mbar-2.2mbar. In one embodiment of the present application, the deposition power of the second emission layer is 1662 W / m 2 -2660W / m 2 Specifically, the deposition power of the second emission layer can be, but is not limited to, 1662 W / m 2 、1700W / m 2 、1800W / m 2 、1900W / m 2 , 2000W / m 2 , 2200W / m 2 , 2400W / m 2 or 2660W / m 2 In one embodiment of the present application, the deposition power of the second emission layer can be 1662W / m 2 -2160W / m 2 In another embodiment of the present application, the deposition power of the second emission layer can be 2200W / m 2 -2660W / m 2. In one embodiment of the present application, when the second emission layer is deposited, the hydrogen flow rate is 30000sccm-50000sccm. Specifically, the hydrogen flow rate may be but not limited to 30000sccm, 35000sccm, 40000sccm, 45000sccm or 50000sccm, etc. In one embodiment of the present application, when the second emission layer is deposited, the hydrogen flow rate may be 30000sccm-45500sccm. In another embodiment of the present application, when the second emission layer is deposited, the hydrogen flow rate may be 35000sccm-50000sccm. In one embodiment of the present application, when the second emission layer is deposited, the silane flow rate is 30sccm-160sccm. Specifically, the silane flow rate may be but not limited to 30sccm, 80sccm, 90sccm, 80sccm, 90sccm or 100sccm, etc. In one embodiment of the present application, when the second emission layer is deposited, the silane flow rate may be 50sccm-85sccm. In another embodiment of the present application, when the second emission layer is deposited, the silane flow rate may be 65sccm-100sccm. In one embodiment of the present application, when the second emission layer is deposited, the flow rate of the diborane hydrogen mixture is 20sccm-30sccm. In the diborane hydrogen mixture, the flow rate of the diborane gas is 0.4sccm-0.6ccm, and the flow rate of the hydrogen gas is 19.4sccm-29.6ccm. Specifically, the flow rate of the diborane hydrogen mixture may be, but is not limited to, 20sccm, 22sccm, 24sccm, 26sccm, 28sccm or 30sccm, etc. In one embodiment of the present application, when the second emission layer is deposited, the flow rate of the diborane hydrogen mixture may be 20sccm-26sccm. In another embodiment of the present application, when the second emission layer is deposited, the flow rate of the diborane hydrogen mixture can be 24sccm-30sccm. In one embodiment of the present application, when the second emission layer is deposited, the flow doping ratio of diborane and silane is 0.3%-1%. Specifically, the flow doping ratio of diborane and silane can be but not limited to 0.3%, 0.5%, 0.7%, 0.9% or 1%, etc. In one embodiment of the present application, when the second emission layer is deposited, the flow doping ratio of diborane and silane can be 0.3%-0.6%. In another embodiment of the present application, when the second emission layer is deposited, the flow doping ratio of diborane and silane can be 0.5%-1%.

[0110] See also Fig.10 , is a flow chart of a method for preparing a solar cell provided in one embodiment of the present application, comprising:

[0111] S301: depositing a first passivation layer, a first seed layer, a first emission layer and a first electrode layer in sequence on the surface of the silicon substrate to obtain a first film layer, wherein the first passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer;

[0112] S302: A second passivation layer, a second seed layer, a second emission layer and a second electrode layer are sequentially deposited on a surface of the first passivation layer away from the silicon substrate to obtain a second film layer, wherein the second passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer to obtain a solar cell.

[0113] In one embodiment of the present application, the deposition temperature of the first passivation layer is 160°C-190°C. Specifically, the deposition temperature of the first passivation layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C or 190°C, etc. In one embodiment of the present application, the deposition temperature of the first passivation layer may be 160°C-180°C. In another embodiment of the present application, the deposition temperature of the first passivation layer may be 170°C-190°C. In one embodiment of the present application, the deposition pressure of the first passivation layer is 0.5mbar-1.5mbar. Specifically, the deposition pressure of the first passivation layer may be, but is not limited to, 0.5mbar, 0.8mbar, 0.9mbar, 1mbar, 1.2mbar, 1.4mbar or 1.5mbar, etc. In one embodiment of the present application, the deposition pressure of the first passivation layer may be 0.5mbar-1mbar. In another embodiment of the present application, the deposition pressure of the first passivation layer may be 0.8mbar-1.5mbar. In one embodiment of the present application, the deposition power of the first passivation layer is 166 W / m 2 -664W / m 2 Specifically, the deposition power of the first passivation layer may be, but is not limited to, 166 W / m 2 , 200W / m 2 、300W / m 2 , 400W / m 2 , 500W / m 2 、600W / m 2 or 664W / m 2 In one embodiment of the present application, the deposition power of the first passivation layer can be 166 W / m 2 -400W / m 2 In another embodiment of the present application, the deposition power of the first passivation layer can be 350 W / m 2 -664W / m 2. In one embodiment of the present application, when the first passivation layer is deposited, the silane flow rate is 150sccm-500sccm. Specifically, the silane flow rate of the first passivation layer may be, but is not limited to, 150sccm, 200sccm, 250sccm, 300sccm, 400sccm or 500sccm, etc. In one embodiment of the present application, the silane flow rate of the first passivation layer may be 150sccm-400sccm. In another embodiment of the present application, the silane flow rate of the first passivation layer may be 300sccm-500sccm. In one embodiment of the present application, when the first passivation layer is deposited, the hydrogen flow rate is 1500sccm-2500sccm. Specifically, the hydrogen flow rate of the first passivation layer may be, but is not limited to, 1500sccm, 1700sccm, 1800sccm, 1900sccm, 2000sccm, 2200 or 2500sccm, etc. In one embodiment of the present application, the hydrogen flow rate of the first passivation layer may be 1500 sccm-2000 sccm. In another embodiment of the present application, the hydrogen flow rate of the first passivation layer may be 1900 sccm-2500 sccm.

[0114] In one embodiment of the present application, carbon dioxide plasma treatment is performed after the first passivation layer is formed. An ultra-thin amorphous silicon oxide layer can be formed on the surface of the first passivation layer by carbon dioxide plasma treatment, and its tunneling effect is used to improve the carrier transmission capacity. In one embodiment of the present application, the temperature of carbon dioxide plasma treatment is 200°C-210°C. Specifically, the temperature of carbon dioxide plasma treatment may be, but not limited to, 200°C, 202°C, 204°C, 206°C, 208°C or 210°C. In one embodiment of the present application, the temperature of carbon dioxide plasma treatment may be 200°C-204°C. In another embodiment of the present application, the temperature of carbon dioxide plasma treatment may be 202°C-210°C. In one embodiment of the present application, the pressure of carbon dioxide plasma treatment is 0.5mbar-2mbar. Specifically, the pressure of carbon dioxide plasma treatment may be, but not limited to, 0.5mbar, 0.8mbar, 1.2mbar, 1.5mbar, 1.8mbar or 2mbar. In one embodiment of the present application, the pressure of carbon dioxide plasma treatment may be 0.5mbar-1.2mbar. In another embodiment of the present application, the pressure of the carbon dioxide plasma treatment can be 1.1 mbar-2 mbar. In one embodiment of the present application, the power of the carbon dioxide plasma treatment is 66.4 W / m 2 -200W / m 2 Specifically, the power of the carbon dioxide plasma treatment may be, but is not limited to, 66.4 W / m 2 , 100W / m 2 、120W / m2 、140W / m 2 、160W / m 2 、180W / m 2 or 200W / m 2 In one embodiment of the present application, the power of the carbon dioxide plasma treatment can be 66.4 W / m 2 -130W / m 2 In another embodiment of the present application, the power of the carbon dioxide plasma treatment can be 120W / m 2 -200W / m 2 . In one embodiment of the present application, the time of carbon dioxide plasma treatment is 5s-15s. Specifically, the time of carbon dioxide plasma treatment may be, but not limited to, 5s, 6s, 7s, 8s, 10s, 12s, 14s or 15s, etc. In one embodiment of the present application, the time of carbon dioxide plasma treatment may be 5s-12s. In another embodiment of the present application, the time of carbon dioxide plasma treatment may be 10s-15s. In one embodiment of the present application, the carbon dioxide flow rate in carbon dioxide plasma treatment is 50sccm-200sccm. Specifically, the carbon dioxide flow rate of carbon dioxide plasma treatment may be, but not limited to, 50sccm, 80sccm, 90sccm, 120sccm, 150sccm, 180sccm or 200sccm, etc. In one embodiment of the present application, the carbon dioxide flow rate of carbon dioxide plasma treatment may be 50sccm-120sccm. In another embodiment of the present application, the carbon dioxide flow rate of carbon dioxide plasma treatment may be 100sccm-200sccm.

[0115] In one embodiment of the present application, the deposition temperature of the second passivation layer is 160°C-190°C. Specifically, the deposition temperature of the second passivation layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C or 190°C. In one embodiment of the present application, the deposition temperature of the second passivation layer may be 160°C-180°C. In another embodiment of the present application, the deposition temperature of the second passivation layer may be 170°C-190°C. In one embodiment of the present application, the deposition power of the second passivation layer is 166W / m 2 -664W / m 2 Specifically, the deposition power of the second passivation layer may be, but is not limited to, 166 W / m 2 , 200W / m 2 、300W / m 2 , 400W / m 2 , 500W / m 2 、600W / m 2 or 664W / m 2In one embodiment of the present application, the deposition power of the second passivation layer can be 166 W / m 2 -400W / m 2 In another embodiment of the present application, the deposition power of the second passivation layer can be 350 W / m 2 -664W / m 2 . In one embodiment of the present application, the deposition pressure of the second passivation layer is 0.5mbar-1.5mbar. Specifically, the deposition pressure of the second passivation layer may be, but is not limited to, 0.5mbar, 0.8mbar, 0.9mbar, 1mbar, 1.2mbar, 1.4mbar or 1.5mbar, etc. In one embodiment of the present application, the deposition pressure of the second passivation layer may be 0.5mbar-1mbar. In another embodiment of the present application, the deposition pressure of the second passivation layer may be 0.8mbar-1.5mbar. In one embodiment of the present application, when the second passivation layer is deposited, the silane flow rate is 150sccm-500sccm. Specifically, the silane flow rate of the second passivation layer may be, but is not limited to, 150sccm, 200sccm, 250sccm, 300sccm, 400sccm or 500sccm, etc. In one embodiment of the present application, the silane flow rate of the second passivation layer may be 150sccm-400sccm. In another embodiment of the present application, the silane flow rate of the second passivation layer may be 300sccm-500sccm. In one embodiment of the present application, during the deposition of the second passivation layer, the hydrogen flow rate is 1500sccm-2500sccm. Specifically, the hydrogen flow rate of the second passivation layer may be, but is not limited to, 1500sccm, 1700sccm, 1800sccm, 1900sccm, 2000sccm, 2200 or 2500sccm, etc. In one embodiment of the present application, the hydrogen flow rate of the second passivation layer may be 1500sccm-2000sccm. In another embodiment of the present application, the hydrogen flow rate of the second passivation layer may be 1900sccm-2500sccm.

[0116] In one embodiment of the present application, carbon dioxide plasma treatment is performed after the second passivation layer is formed. Carbon dioxide plasma treatment can form an ultra-thin amorphous silicon oxide layer on the surface of the second passivation layer, and its tunneling effect is utilized to improve the carrier transmission capacity. In one embodiment of the present application, the temperature of the carbon dioxide plasma treatment is 200°C-210°C. Specifically, the temperature of the carbon dioxide plasma treatment may be but is not limited to 200°C, 202°C, 204°C, 206°C, 208°C or 210°C, etc. In one embodiment of the present application, the temperature of the carbon dioxide plasma treatment may be 200°C-204°C. In another embodiment of the present application, the temperature of the carbon dioxide plasma treatment may be 202°C-210°C. In one embodiment of the present application, the power of the carbon dioxide plasma treatment is 66.4W / m 2 -200W / m 2 Specifically, the power of the carbon dioxide plasma treatment may be, but is not limited to, 66.4 W / m 2 , 100W / m 2 、120W / m 2 、140W / m 2 、160W / m 2 、180W / m 2 or 200W / m 2 In one embodiment of the present application, the power of carbon dioxide plasma treatment can be 66.4W / m 2 -150W / m 2 In another embodiment of the present application, the power of the carbon dioxide plasma treatment can be 120W / m 2 -200W / m 2. In one embodiment of the present application, the pressure of the carbon dioxide plasma treatment is 0.5mbar-2mbar. Specifically, the pressure of the carbon dioxide plasma treatment may be, but is not limited to, 0.5mbar, 0.8mbar, 1.2mbar, 1.5mbar, 1.8mbar or 2mbar, etc. In one embodiment of the present application, the pressure of the carbon dioxide plasma treatment may be 0.5mbar-1.2mbar. In another embodiment of the present application, the pressure of the carbon dioxide plasma treatment may be 1.1mbar-2mbar. In one embodiment of the present application, the time of the carbon dioxide plasma treatment is 5s-15s. Specifically, the time of the carbon dioxide plasma treatment may be, but is not limited to, 5s, 6s, 7s, 8s, 10s, 12s, 14s or 15s, etc. In one embodiment of the present application, the time of the carbon dioxide plasma treatment may be 5s-12s. In another embodiment of the present application, the time of the carbon dioxide plasma treatment may be 10s-15s. In one embodiment of the present application, the carbon dioxide flow rate in the carbon dioxide plasma treatment is 50sccm-200sccm. Specifically, the carbon dioxide flow rate of the carbon dioxide plasma treatment may be, but is not limited to, 50 sccm, 80 sccm, 90 sccm, 120 sccm, 150 sccm, 180 sccm or 200 sccm, etc. In one embodiment of the present application, the carbon dioxide flow rate of the carbon dioxide plasma treatment may be 50 sccm-120 sccm. In another embodiment of the present application, the carbon dioxide flow rate of the carbon dioxide plasma treatment may be 100 sccm-200 sccm.

[0117] See also Fig.11 , is a flow chart of a method for preparing a solar cell provided in another embodiment of the present application, comprising:

[0118] S401: depositing a first passivation layer, a first seed layer, a first emission layer, a first transition layer and a first electrode layer in sequence on the surface of the silicon substrate to obtain a first film layer, wherein the first passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer;

[0119] S402: A second passivation layer, a second seed layer, a second emission layer, a second transition layer and a second electrode layer are sequentially deposited on a surface facing away from the silicon substrate to obtain a second film layer, wherein the second passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer to obtain a solar cell.

[0120] In one embodiment of the present application, the deposition temperature of the first transition layer is 190°C-210°C. Specifically, the deposition temperature of the first transition layer may be, but not limited to, 190°C, 195°C, 200°C, 206°C, 208°C or 210°C, etc. In one embodiment of the present application, the deposition temperature of the first transition layer may be 190°C-204°C. In another embodiment of the present application, the deposition temperature of the first transition layer may be 202°C-210°C. In one embodiment of the present application, the deposition pressure of the first transition layer is 0.5mbar-1mbar. Specifically, the deposition pressure of the first transition layer may be, but not limited to, 0.5mbar, 0.55mbar, 0.6mbar, 0.8mbar, 0.9mbar or 1mbar, etc. In one embodiment of the present application, the deposition pressure of the first transition layer may be 0.5mbar-0.85mbar. In another embodiment of the present application, the deposition pressure of the first transition layer may be 0.6mbar-1mbar. In one embodiment of the present application, the deposition power of the first transition layer is 265W / m 2 -664W / m 2 Specifically, the deposition power of the first transition layer may be, but is not limited to, 265 W / m 2 、300W / m 2 、350W / m 2 , 400W / m 2 、450W / m 2 , 500W / m 2 、550W / m 2 、600W / m 2 or 664W / m 2 In one embodiment of the present application, the deposition power of the first transition layer can be 265W / m 2 -400W / m 2 In another embodiment of the present application, the deposition power of the first transition layer can be 350 W / m 2 -664W / m 2. In one embodiment of the present application, when the first transition layer is deposited, the hydrogen flow rate is 300sccm-500sccm. Specifically, the hydrogen flow rate may be, but not limited to, 300sccm, 350sccm, 400sccm, 450sccm or 500sccm, etc. In one embodiment of the present application, when the first transition layer is deposited, the hydrogen flow rate may be 300sccm-450sccm. In another embodiment of the present application, when the first transition layer is deposited, the hydrogen flow rate may be 400sccm-500sccm. In one embodiment of the present application, when the first transition layer is deposited, the silane flow rate is 100sccm-200sccm. Specifically, the silane flow rate may be, but not limited to, 100sccm, 120sccm, 140sccm, 150sccm, 170sccm or 200sccm, etc. In one embodiment of the present application, when the first transition layer is deposited, the silane flow rate may be 100sccm-180sccm. In another embodiment of the present application, when the first transition layer is deposited, the silane flow rate may be 160sccm-200sccm. In one embodiment of the present application, when the first transition layer is deposited, the flow rate of the phosphine hydrogen mixture is 300sccm-500sccm. In the phosphine hydrogen mixture, the flow rate of the phosphine gas is 6sccm-10ccm, and the flow rate of the hydrogen gas is 290sccm-494ccm. Specifically, the flow rate of the phosphine hydrogen mixture may be, but is not limited to, 300sccm, 320sccm, 380sccm, 400sccm, 4500sccm or 500sccm, etc. In one embodiment of the present application, when the first transition layer is deposited, the flow rate of the phosphine hydrogen mixture may be 300sccm-450sccm. In another embodiment of the present application, when the first transition layer is deposited, the flow rate of the phosphine hydrogen mixture may be 380sccm-500sccm.

[0121] In one embodiment of the present application, the deposition temperature of the second transition layer is 160°C-180°C. Specifically, the deposition temperature of the second transition layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C or 180°C. In one embodiment of the present application, the deposition temperature of the second transition layer may be 160°C-170°C. In another embodiment of the present application, the deposition temperature of the second transition layer may be 165°C-180°C. In one embodiment of the present application, the deposition power of the second transition layer is 1661W / m 2 -2658W / m 2 Specifically, the deposition power of the second transition layer may be, but is not limited to, 1661 W / m 2 、1700W / m 2 、1800W / m 2 、1900W / m 2 , 2000W / m 2、2100W / m 2 , 2400W / m 2 、2600W / m 2 or 2658W / m 2 Etc. In one embodiment of the present application, the deposition power of the second transition layer may be 2500W-2980W. In another embodiment of the present application, the deposition power of the second transition layer may be 2800W-4000W. In one embodiment of the present application, the deposition pressure of the second transition layer is 2mbar-4mbar. Specifically, the deposition pressure of the second transition layer may be, but not limited to, 2mbar, 2.2mbar, 2.5mbar, 2.8mbar, 3mbar, 3.5mbar or 4mbar, etc. In one embodiment of the present application, the deposition pressure of the second transition layer may be 2mbar-3.5mbar. In another embodiment of the present application, the deposition pressure of the second transition layer may be 3mbar-4mbar. In one embodiment of the present application, when the second transition layer is deposited, the hydrogen flow rate is 30000sccm-50000sccm. Specifically, the hydrogen flow rate may be, but not limited to, 30000sccm, 35000sccm, 40000sccm, 45000sccm or 50000sccm, etc. In one embodiment of the present application, when the second transition layer is deposited, the hydrogen flow rate may be 30000sccm-45500sccm. In another embodiment of the present application, when the second transition layer is deposited, the hydrogen flow rate may be 35000sccm-50000sccm. In one embodiment of the present application, when the second transition layer is deposited, the silane flow rate is 30sccm-160sccm. Specifically, the silane flow rate may be, but is not limited to, 30sccm, 80sccm, 90sccm, 80sccm, 90sccm or 100sccm, etc. In one embodiment of the present application, when the second transition layer is deposited, the silane flow rate may be 50sccm-85sccm. In another embodiment of the present application, when the second transition layer is deposited, the silane flow rate may be 65sccm-100sccm. In one embodiment of the present application, when the second transition layer is deposited, the flow rate of the diborane hydrogen mixture is 200sccm-300sccm. In the diborane hydrogen gas mixture, the flow rate of the diborane gas is 4sccm-6ccm, and the flow rate of the hydrogen gas is 194sccm-296ccm. Specifically, the flow rate of the diborane hydrogen gas mixture can be, but is not limited to, 200sccm, 220sccm, 240sccm, 260sccm, 280sccm or 300sccm, etc. In one embodiment of the present application, when the second transition layer is deposited, the flow rate of the diborane hydrogen gas mixture can be 200sccm-260sccm. In another embodiment of the present application, when the second transition layer is deposited, the flow rate of the diborane hydrogen gas mixture can be 240sccm-300sccm.

[0122] See also Fig.12 , is a flow chart of a method for preparing a solar cell provided in another embodiment of the present application, comprising:

[0123] S501: depositing a first passivation layer, a first seed layer, a first emission layer, a first transition layer and a first electrode layer in sequence on the surface of the silicon substrate to obtain a first film layer, wherein the first passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer;

[0124] S502: A second passivation layer, a second seed layer, a second emission layer, a second transition layer, a buffer layer and a second electrode layer are sequentially deposited on a surface facing away from the silicon substrate to obtain a second film layer, wherein the second passivation layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer to obtain a solar cell.

[0125] In one embodiment of the present application, after forming the second transition layer, a buffer layer is deposited on the surface of the second transition layer to improve the contact between the upper and lower film layers to increase the short-circuit current and fill factor. When depositing the second electrode layer, the buffer layer can protect the second transition layer to prevent the second electrode layer from damaging the second transition layer.

[0126] In one embodiment of the present application, the deposition temperature of the buffer layer is 160°C-180°C. Specifically, the deposition temperature of the buffer layer may be, but is not limited to, 160°C, 165°C, 170°C, 175°C or 180°C, etc. In one embodiment of the present application, the deposition temperature of the buffer layer may be 160°C-170°C. In another embodiment of the present application, the deposition temperature of the buffer layer may be 165°C-180°C. In one embodiment of the present application, the deposition pressure of the buffer layer is 0.3mbar-1mbar. Specifically, the deposition pressure of the buffer layer may be, but is not limited to, 0.3mbar, 0.4mbar, 0.5mbar, 0.6mbar, 0.7mbar, 0.8mbar or 1mbar, etc. In one embodiment of the present application, the deposition pressure of the buffer layer may be 0.3mbar-0.8mbar. In another embodiment of the present application, the deposition pressure of the buffer layer may be 0.5mbar-1mbar. In one embodiment of the present application, the deposition power of the buffer layer is 332W / m 2 -664W / m 2 Specifically, the deposition power of the buffer layer may be, but is not limited to, 332 W / m 2 、350W / m 2 , 400W / m 2 、450W / m 2 , 500W / m 2 、550W / m 2、600W / m 2 or 664W / m 2 In one embodiment of the present application, the deposition power of the buffer layer can be 332 W / m 2 -500W / m 2 In another embodiment of the present application, the deposition power of the buffer layer can be 450 W / m 2 -664W / m 2 . In one embodiment of the present application, when the buffer layer is deposited, the carbon dioxide flow rate is 100sccm-200sccm. Specifically, the hydrogen flow rate may be, but not limited to, 100sccm, 120sccm, 150sccm, 180sccm or 200sccm, etc. In one embodiment of the present application, when the buffer layer is deposited, the hydrogen flow rate may be 100sccm-155sccm. In another embodiment of the present application, when the buffer layer is deposited, the hydrogen flow rate may be 120sccm-200sccm. In one embodiment of the present application, when the buffer layer is deposited, the hydrogen flow rate is 300sccm-500sccm. Specifically, the hydrogen flow rate may be, but not limited to, 300sccm, 350sccm, 400sccm, 450sccm or 500sccm, etc. In one embodiment of the present application, when the buffer layer is deposited, the hydrogen flow rate may be 300sccm-455sccm. In another embodiment of the present application, when the buffer layer is deposited, the hydrogen flow rate may be 350sccm-500sccm. In one embodiment of the present application, when the buffer layer is deposited, the silane flow rate is 100sccm-200sccm. Specifically, the silane flow rate may be, but is not limited to, 100sccm, 120sccm, 140sccm, 160sccm, 180sccm or 200sccm, etc. In one embodiment of the present application, when the buffer layer is deposited, the silane flow rate may be 100sccm-165sccm. In another embodiment of the present application, when the buffer layer is deposited, the silane flow rate may be 140ccm-200sccm. In one embodiment of the present application, when the buffer layer is deposited, the flow rate of the diborane hydrogen mixture is 400sccm-600sccm. In the diborane hydrogen mixture, the flow rate of the diborane gas is 8sccm-12ccm, and the flow rate of the hydrogen gas is 388sccm-592ccm. Specifically, the flow rate of the diborane-hydrogen mixture may be, but is not limited to, 400 sccm, 420 sccm, 450 sccm, 500 sccm, 550 sccm or 600 sccm, etc. In one embodiment of the present application, during the deposition of the buffer layer, the flow rate of the diborane-hydrogen mixture may be 400 sccm-560 sccm. In another embodiment of the present application, during the deposition of the buffer layer, the flow rate of the diborane-hydrogen mixture may be 500 sccm-600 sccm.

[0127] In one embodiment of the present application, hydrogen plasma treatment is also included before and / or after forming the first seed layer, the first emission layer, the first transition layer, the second passivation layer, the second seed layer, the second emission layer, the second transition layer, and the buffer layer, which can improve the crystallization rate and growth defects of each film layer. At the same time, the first passivation layer is not treated with hydrogen plasma, and the silicon oxide formed by natural oxidation on the surface of the first passivation layer is retained, which is beneficial to the transmission of carriers and electrons and to improve the carrier transmission efficiency. In one embodiment of the present application, after the second passivation layer is deposited and before the carbon dioxide plasma treatment is performed, hydrogen plasma treatment is also included, using a large amount of hydrogen plasma to compensate for the dangling bonds of the surface silicon in the second emission layer, while providing a hydrogen-rich environment for the second transition layer to reduce the possibility of film explosion.

[0128] In one embodiment of the present application, the pressure of the hydrogen plasma treatment is 0.5mbar-1.5mbar. Specifically, the pressure of the hydrogen plasma treatment may be but is not limited to 0.5mbar, 1mbar, 1.3mbar, 1.35mbar, 1.4mbar or 1.5mbar, etc. In one embodiment of the present application, before the first seed layer is formed, the pressure of the hydrogen plasma treatment may be 1.2mbar-1.5mbar, etc. In another embodiment of the present application, before the second seed layer is formed, the pressure of the hydrogen plasma treatment may be 0.5mbar-1mbar. In one embodiment of the present application, the power of the hydrogen plasma treatment is 119W / m 2 -332W / m 2 Specifically, the power of hydrogen plasma treatment can be, but is not limited to, 119 W / m 2 、150W / m 2 、180W / m 2 , 200W / m 2 、220W / m 2 、280W / m 2 、290W / m 2 、300W / m 2 or 332W / m 2 In one embodiment of the present application, the power of hydrogen plasma treatment can be 119W / m 2 -220W / m 2 In another embodiment of the present application, the power of hydrogen plasma treatment can be 210W / m 2 -332W / m 2. In one embodiment of the present application, the time of hydrogen plasma treatment is 8s-40s. Specifically, the time of hydrogen plasma treatment may be, but not limited to, 8s, 10s, 18s, 20s, 25s, 30s or 40s, etc. In one embodiment of the present application, before the first seed layer is formed, the time of hydrogen plasma treatment may be 8s-15s. In another embodiment of the present application, before the second seed layer is formed, the time of hydrogen plasma treatment may be 20s-40s. In one embodiment of the present application, the hydrogen flow rate of hydrogen plasma treatment is 1500sccm-3000sccm. Specifically, the carbon dioxide flow rate of hydrogen plasma treatment may be, but not limited to, 1500sccm, 1600sccm, 1850sccm, 2000sccm, 2500sccm, 2900sccm or 3000sccm, etc. In one embodiment of the present application, before the first seed layer, the first emission layer and the first transition layer are formed, the hydrogen flow rate of hydrogen plasma treatment may be 1500sccm-2000sccm. In another embodiment of the present application, before the second seed layer, the second emission layer, the second transition layer and / or the buffer layer are formed, the hydrogen flow rate of the hydrogen plasma treatment can be 2000 sccm-3000 sccm.

[0129] The present application also provides a solar cell, which includes a solar cell provided by any one of the above embodiments. The solar cell provided by the present application has high photoelectric conversion efficiency and good safety in use, which is conducive to improving the application of solar cells.

[0130] The present application also provides an electrical device, the electrical device comprising the solar cell provided by any one of the above embodiments. The electrical device provided by the present application has excellent comprehensive performance and high photoelectric conversion efficiency, thereby improving the market competitiveness of the electrical device.

[0131] The effect of the technical solution of this application is further illustrated below through specific examples.

[0132] Example 1

[0133] The first passivation layer and the second passivation layer were deposited by plasma chemical vapor deposition using an RF power supply with a frequency of 13.56 MHz on both sides of the N-type silicon substrate, wherein the coating temperature was 190 ° C, the pressure was 1.2 mbar, and the power was 531 W / m 2 , the silane flow rate is 160 sccm, and the hydrogen flow rate is 1600 sccm. The material of the first passivation layer is amorphous silicon with a thickness of 7.5 nm, and the material of the second passivation layer is amorphous silicon with a thickness of 13 nm.

[0134] The surface of the first passivation layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 1600 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0135] The first passivation layer was treated with carbon dioxide plasma using a VHF power supply with a frequency of 40 MHz. The carbon dioxide flow rate during the carbon dioxide plasma treatment was 160 sccm, the pressure was 0.7 mbar, and the power was 106 W / m 2 , time is 10s, temperature is 205℃.

[0136] The first seed layer was deposited on the surface of the first passivation layer after the carbon dioxide plasma treatment using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature was 210°C, the deposition pressure was 3 mbar, and the deposition power was 664 W / m 2 The hydrogen flow rate is 11000sccm, the silane flow rate is 25sccm, the phosphine hydrogen mixed gas flow rate is 50sccm, and the phosphine / silane flow doping ratio is controlled at 4%. The material of the first seed layer is microcrystalline silicon containing phosphorus doping elements, the crystallization rate is about 0.3, the film thickness is 3nm, and the doping molar ratio of phosphorus to silicon is 1:25.

[0137] The surface of the first seed layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 1600 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0138] The first emission layer is deposited on the surface of the first seed layer using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature is 200°C, the deposition pressure is 3 mbar, and the deposition power is 1661 W / m 2 The hydrogen flow rate is 11000sccm, the silane flow rate is 66sccm, the phosphine hydrogen mixed gas flow rate is 180sccm, and the phosphine / silane flow doping ratio is controlled at 5.4%. The material of the first emission layer is microcrystalline silicon oxide containing phosphorus doping elements, the crystallization rate is about 0.45, the film thickness is 15nm, and the doping molar ratio of phosphorus to silicon is 1:18.

[0139] The surface of the first emission layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 1600.0 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0140] The first transition layer is deposited on the surface of the first emission layer using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature is 200°C, the deposition pressure is 1 mbar, and the deposition power is 664 W / m 2 The hydrogen flow rate is 11000sccm, the silane flow rate is 66sccm, the phosphine hydrogen mixed gas flow rate is 264sccm, and the phosphine / silane flow doping ratio is controlled at 8%. The material of the first transition layer is microcrystalline silicon containing phosphorus doping elements, the film thickness is 2nm, and the doping molar ratio of phosphorus to silicon is 1:12.5.

[0141] The surface of the second passivation layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 2400 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0142] The second passivation layer after hydrogen treatment was treated with carbon dioxide plasma using a VHF power supply with a frequency of 40 MHz. The carbon dioxide flow rate during the carbon dioxide plasma treatment was 720 sccm, the pressure was 0.7 mbar, and the power was 106 W / m 2 , time is 10s, temperature is 200℃.

[0143] The second seed layer was deposited on the surface of the second passivation layer after the carbon dioxide plasma treatment using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature was 170°C, the deposition pressure was 2.25 mbar, and the deposition power was 2259 W / m 2 The hydrogen flow rate is 20000sccm, the silane flow rate is 40sccm, the diborane hydrogen mixed gas flow rate is 100-200sccm, and the diborane / silane flow doping ratio is controlled at 7%. The material of the second seed layer is microcrystalline silicon containing boron doping elements, the crystallization rate is about 0.35, the film thickness is 1-3nm, and the doping molar ratio of boron element to silicon element is 1:7.

[0144] The surface of the second seed layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 2400 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0145] The second emission layer was deposited on the surface of the second seed layer using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature was 170°C, the deposition pressure was 3.7 mbar, and the deposition power was 2658 W / m 2The hydrogen flow rate is 40200sccm, the silane flow rate is 120sccm, the diborane hydrogen mixed gas flow rate is 20sccm, and the diborane / silane flow doping ratio is controlled at 0.33%. The material of the second emission layer is microcrystalline silicon containing boron doping elements, the crystallization rate is about 0.5, the film thickness is 25nm, and the doping molar ratio of boron element to silicon element is 1:150.

[0146] The surface of the second emission layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 2400 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0147] The second transition layer is deposited on the surface of the second emission layer using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature is 170°C, the deposition pressure is 3.5 mbar, and the deposition power is 3987 W / m 2 The hydrogen flow rate is 40200sccm, the silane flow rate is 200sccm, the diborane hydrogen mixed gas flow rate is 300sccm, and the diborane silane flow doping ratio is controlled at 3%. The material of the second transition layer is microcrystalline silicon containing boron doping elements, the film thickness is 5-6nm, and the doping molar ratio of boron element to silicon element is 2:33.

[0148] The surface of the second transition layer was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 2400 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0149] The buffer layer was deposited on the surface of the second transition layer using a VHF power supply with a frequency of 40 MHz, wherein the deposition temperature was 170°C, the deposition pressure was 0.5 mbar, and the deposition power was 531 W / m 2 , the hydrogen flow rate is 675sccm, the silane flow rate is 150sccm, the carbon dioxide flow rate is 50sccm, the diborane hydrogen mixed gas flow rate is 500sccm, and the diborane / silane flow doping ratio is controlled at 6%. The material of the buffer layer is amorphous silicon oxide containing boron doping elements, the film thickness is 1-2nm, and the doping molar ratio of boron and silicon elements is 2:15.

[0150] The buffer layer surface was treated with hydrogen plasma using a VHF power supply with a frequency of 40 MHz. During the hydrogen plasma treatment, the hydrogen flow rate was 2400 sccm, the pressure was 0.7 mbar, and the power was 249 W / m 2 , time is 30s.

[0151] A first transparent conductive layer is formed on the surface of the first transition layer by physical vapor deposition, the thickness of the first transparent conductive layer is 90 nm, and then the first electrode is screen-printed.

[0152] A second transparent conductive layer is formed on the surface of the buffer layer by physical vapor deposition, the thickness of the second transparent conductive layer is 110 nm, and then a second electrode is screen-printed to obtain a solar cell.

[0153] Example 2

[0154] The difference from Example 1 is that the material of the second seed layer is microcrystalline silicon oxide containing boron doping elements.

[0155] Example 3

[0156] The difference from Example 1 is that the material of the second seed layer is intrinsic microcrystalline silicon oxide.

[0157] Example 4

[0158] The difference from the first embodiment is that the material of the buffer layer is amorphous silicon containing boron doping elements.

[0159] Example 5

[0160] The difference from Example 1 is that there is no buffer layer.

[0161] Example 6

[0162] The difference from Example 1 is that the doping ratios of phosphine and silane in the first seed layer, the first emission layer and the first transition layer are the same, and the doping molar ratios of phosphorus and silicon are both 1:25.

[0163] Example 7

[0164] The difference from the first embodiment is that the first transition layer and the second transition layer are not provided.

[0165] Example 8

[0166] The difference from Example 1 is that an RF power supply with a frequency of 13.56 MHz is used instead of a VHF power supply in all film depositions.

[0167] Example 9

[0168] The difference from Example 1 is that the crystallization rate of the first seed layer is 0.3, and the crystallization rate of the first emission layer is 0.7.

[0169] Example 10

[0170] The difference from Example 1 is that the crystallization rate of the first seed layer is 0.6, and the crystallization rate of the first emission layer is 0.7.

[0171] Embodiment 11

[0172] The difference from Example 1 is that the material of the first seed layer is microcrystalline silicon carbide.

[0173] Example 12

[0174] The difference from Example 1 is that the second passivation layer is not subjected to hydrogen plasma treatment.

[0175] Example 13

[0176] The difference from Example 1 is that the doping molar ratio of phosphorus element to silicon element in the first seed layer is 1:10, and the doping molar ratio of boron element to silicon element in the second seed layer is 1:15.

[0177] Embodiment 14

[0178] The difference from Example 1 is that the first passivation layer and the second passivation layer are not treated with carbon dioxide plasma, the crystallization rate of the first seed layer is 0.2, and the crystallization rate of the second seed layer is 0.2.

[0179] Embodiment 15

[0180] The difference from Example 1 is that the crystallization rate of the first seed layer is 0.2, the crystallization rate of the first emission layer is 0.8, the crystallization rate of the second seed layer is 0.8, and the crystallization rate of the second emission layer is 0.8.

[0181] Comparative Example 1

[0182] The difference from Example 1 is that there is no first seed layer, second seed layer, first transition layer, second transition layer and buffer layer, the first passivation layer and the second passivation layer are not treated with carbon dioxide plasma, the materials of the first emission layer and the second emission layer are both amorphous silicon, the crystallization rate of the first emission layer and the second emission layer does not change, and the crystallization rate is below 0.1.

[0183] Comparative Example 2

[0184] The difference from Example 1 is that the first seed layer and the first emission layer have the same crystallization rate, and the second seed layer and the second emission layer have the same crystallization rate.

[0185] Comparative Example 3

[0186] The difference from Embodiment 1 is that the first emission layer and the second emission layer do not include the first doping element and the second doping element.

[0187] Performance Testing

[0188] The photovoltaic current-voltage characteristics of the solar cells prepared in the above-mentioned embodiments 1-15 and comparative examples 1-3 were tested according to the IEC60904-1-2020 standard to obtain the open circuit voltage (U oc ), short circuit current (I sc ), fill factor (FF), photoelectric conversion efficiency (Eta) and maximum output power (P mpp ), the results are shown in Table 1, where the open circuit voltage (U oc ): The voltage that can be generated when the solar cell is in the open circuit state, generally the theoretical maximum voltage of the battery; short-circuit current (I sc ): It reflects the current that a solar cell can generate under no-load conditions, which is generally the theoretical maximum current of the battery. Fill factor (FF): The ratio of the power to the product of the open-circuit voltage and the short-circuit current when the battery has maximum output power is called the fill factor. When the open-circuit voltage and the short-circuit current are fixed, the higher the fill factor, the higher the battery conversion efficiency. Photoelectric conversion efficiency (Eta): It is the ratio of the output power of a solar cell to the incident solar light power under the corresponding conditions (Formula I). ​​It is the most important performance parameter of a solar cell, reflecting the ability of the cell to convert light energy into electrical energy. The higher the better. It is generally taken as the ratio of the maximum output power to the incident solar light power. Maximum output power (P mpp ): The voltage and current corresponding to the maximum output power are the maximum output voltage U mpp and the maximum output current I mpp ,

[0189]

[0190] The data obtained from the photovoltaic current-voltage characteristic detection is normalized, and the normalization formula is:

[0191]

[0192] For example, the conversion efficiency of a certain embodiment is 25.3%, and the conversion efficiency of comparative example 1 is 25%, then the normalized conversion efficiency of this embodiment is 101.2%. Normalized data (open circuit voltage (U oc ), short circuit current (I sc ), fill factor (FF), photoelectric conversion efficiency (Eta) and maximum output power (P mpp ))As shown in Table 1.

[0193] Fig.13 This is a surface morphology of the solar cell after coating provided in Example 1 of the present application. Fig.14This is a surface morphology of the solar cell after coating provided in Comparative Example 1 of the present application; Example 1 and Comparative Example 1 use the same coating method, and it can be seen through the naked eye or a microscope that there are uneven particles / powder on the surface, resulting in film bursting.

[0194] Table 1 Photovoltaic current-voltage characteristics test results

[0195]

[0196] According to Examples 1-15 and Comparative Examples 1-3, it can be seen that the crystal quality of the solar cell film layer provided by the present application is suitable, the probability of film explosion is low, and the reliability of the overall structure is high; at the same time, the ability of each film layer in the solar cell to collect carriers is strong, which improves the open circuit voltage, short circuit current and fill factor of the solar cell, and further improves the photoelectric conversion efficiency of the solar cell. According to Examples 1-15, it can be seen that carbon dioxide plasma treatment, hydrogen plasma treatment, suitable preparation methods, suitable doping element content, suitable film layer design and suitable film layer material selection can further improve the electrochemical performance and photoelectric conversion efficiency of the solar cell. According to Examples 1 and 13, it can be seen that further optimizing the ratio of doping elements to silicon elements can improve the electrochemical performance of solar cells. According to Examples and Comparative Examples 1-3, it can be seen that the presence of doping elements and the formation of a gradient of molar ratio of doping elements to silicon elements in the solar cell can reduce the interface defects and contact resistance of the solar cell, thereby improving the electrochemical performance of the solar cell.

[0197] The above is a preferred embodiment of the present application, but it should not be understood as limiting the scope of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: The solar cell comprises a silicon substrate, a first film layer arranged on the surface of the silicon substrate, and a second film layer arranged on the surface of the silicon substrate on a side away from the first film layer; In the direction from the silicon substrate to the first film layer, the first film layer includes a first emission layer and a first electrode layer stacked in sequence, the first emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer close to the first electrode layer is greater than the crystallization rate of the first emission layer close to the silicon substrate; and / or Along the direction from the silicon substrate to the second film layer, the second film layer includes a second emission layer and a second electrode layer stacked in sequence, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer close to the second electrode layer is greater than the crystallization rate of the second emission layer close to the silicon substrate; The first emission layer has a first doping element, the second emission layer has a second doping element, the silicon substrate has the first doping element or the second doping element, and the first doping element is different from the second doping element.

2. The solar cell according to claim 1, wherein: Along the direction from the silicon substrate to the first film layer, the first emission layer includes a first seed layer and a first emission layer which are stacked, the first seed layer is connected to the surface of the silicon substrate, the first emission layer is connected to the first electrode layer, the crystallization rate of the first seed layer is 0.3-0.6, and the crystallization rate of the first emission layer is greater than the crystallization rate of the first seed layer; and / or Along the direction from the silicon substrate to the second film layer, the second emission layer includes a second seed layer and a second emission layer that are stacked, the second seed layer is connected to the surface of the silicon substrate, the second emission layer is connected to the second electrode layer, the crystallization rate of the second seed layer is 0.3-0.6, and the crystallization rate of the second emission layer is greater than the crystallization rate of the second seed layer.

3. The solar cell according to claim 2, wherein: The crystallization rate of the first emission layer is 0.4-0.7; The material of the first seed layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon carbide containing the first doping element, and microcrystalline silicon oxide containing the first doping element; The material of the first emission layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon carbide containing the first doping element, and microcrystalline silicon oxide containing the first doping element; The crystallization rate of the second emission layer is 0.4-0.7; The material of the second seed layer includes at least one of microcrystalline silicon, microcrystalline silicon oxide, microcrystalline silicon carbide, microcrystalline silicon containing the second doping element, microcrystalline silicon carbide containing the second doping element, and microcrystalline silicon oxide containing the second doping element; The material of the second emission layer includes at least one of microcrystalline silicon containing the second doping element, microcrystalline silicon carbide containing the second doping element, and microcrystalline silicon oxide containing the second doping element.

4. The solar cell according to claim 2 or 3, characterized in that: When the second seed layer has the second doping element, a molar ratio of the second doping element to silicon in the second seed layer is greater than a molar ratio of the first doping element to silicon in the first seed layer; The molar ratio of the first doping element to the silicon element in the first emission layer is greater than the molar ratio of the first doping element to the silicon element in the first seed layer.

5. The solar cell according to claim 1, wherein: A first passivation layer is further included between the silicon substrate and the first emission layer, and / or a second passivation layer is further included between the silicon substrate and the second emission layer; The material of the first passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide, and the material of the second passivation layer includes at least one of amorphous silicon, amorphous silicon oxide and silicon carbide.

6. The solar cell according to claim 1, wherein: The first film layer further includes a first transition layer disposed between the first emission layer and the first electrode layer; The material of the first transition layer includes at least one of microcrystalline silicon containing the first doping element, microcrystalline silicon oxide containing the first doping element, and microcrystalline silicon carbide containing the first doping element.

7. The solar cell according to claim 1, wherein: The second film layer further includes a second transition layer disposed between the second emission layer and the second electrode layer; The material of the second transition layer includes at least one of microcrystalline silicon containing the second doping element, microcrystalline silicon oxide containing the second doping element, and microcrystalline silicon carbide containing the second doping element.

8. The solar cell according to claim 1, wherein: The second film layer further includes a buffer layer disposed between the second emission layer and the second electrode layer; The material of the buffer layer includes at least one of amorphous silicon containing the second doping element and amorphous silicon oxide containing the second doping element.

9. The solar cell according to claim 1, wherein: The second film layer further includes a second transition layer and a buffer layer disposed between the second emission layer and the second electrode layer, and the second transition layer is disposed between the second emission layer and the buffer layer.

10. The solar cell according to claim 1, wherein: The photoelectric conversion efficiency of the solar cell is greater than 25%.

11. A method for preparing a solar cell, characterized in that: include: A first film layer and a second film layer are deposited on a silicon substrate to obtain a solar cell; the solar cell comprises a silicon substrate, a first film layer arranged on a surface of the silicon substrate, and a second film layer arranged on a surface of the silicon substrate facing away from the first film layer; along the direction from the silicon substrate to the first film layer, the first film layer comprises a first emission layer and a first electrode layer stacked in sequence, the first emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the first emission layer close to the first electrode layer is greater than the crystallization rate of the first emission layer close to the silicon substrate; and / or along the direction from the silicon substrate to the second film layer, the second film layer comprises a second emission layer and a second electrode layer stacked in sequence, the second emission layer is connected to the surface of the silicon substrate, and the crystallization rate of the second emission layer close to the second electrode layer is greater than the crystallization rate of the second emission layer close to the silicon substrate; the first emission layer has a first doping element, the second emission layer has a second doping element, the silicon substrate has the first doping element or the second doping element, and the first doping element is different from the second doping element.

12. The preparation method according to claim 11, characterized in that: The method further comprises carbon dioxide plasma treatment before preparing the first emission layer and / or the second emission layer.

13. The preparation method according to claim 12, characterized in that: The carbon dioxide flow rate in the carbon dioxide plasma treatment is 50 sccm-200 sccm, the carbon dioxide plasma treatment time is 5s-15s, and the carbon dioxide plasma treatment power is 66W / m 2 -200W / m 2 .

14. A solar cell, characterized in that: The solar cell comprises the solar cell according to any one of claims 1 to 10 or a solar cell prepared by the preparation method according to any one of claims 11 to 13.

15. An electrical equipment, characterized in that: The electrical device comprises the solar cell according to claim 14.

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