Solar cell

Abstract

The invention provides a solar cell. Relates to the field of photovoltaic technology. The solar cell comprises a silicon substrate, a first aluminum oxide layer and a first nitrogen-containing passivation layer, the first aluminum oxide layer is arranged on at least one surface of the silicon substrate, and the first nitrogen-containing passivation layer is arranged on the first aluminum oxide layer; wherein the first aluminum oxide layer contains nitrogen migrated from the first nitrogen-containing passivation layer, and the nitrogen is used for being combined with a defect area on the surface of the silicon substrate to form a nitrogen-silicon bond so as to repair the defect area. By reducing the defect area on the surface of the silicon substrate, aggregation of carriers in the defect area is reduced, the open-circuit voltage is increased, more carriers can be transmitted to the electrode of the solar cell, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] The invention relates to the field of photovoltaic technology, in particular to a solar cell. Background Art

[0002] Currently, in the process of preparing solar cells, a passivation layer can be prepared on a silicon substrate, so that the passivation layer can realize passivation protection of the silicon substrate, thereby improving the photoelectric conversion efficiency of the solar cell.

[0003] However, after a passivation layer is prepared on a silicon substrate, defective regions still exist on the surface of the silicon substrate, and the defective regions will affect the photoelectric conversion efficiency of the solar cell. Summary of the invention

[0004] The present invention provides a solar cell to solve the problem in the prior art that defective regions still exist on the surface of a silicon substrate and the defective regions affect the photoelectric conversion efficiency of the solar cell.

[0005] In order to solve the above problem, the present invention is achieved as follows: In a first aspect, an embodiment of the present invention provides a solar cell, comprising: A silicon substrate, a first aluminum oxide layer, and a first nitrogen-containing passivation layer; The first aluminum oxide layer is disposed on at least one surface of the silicon substrate, and the first nitrogen-containing passivation layer is disposed on the first aluminum oxide layer; The first aluminum oxide layer contains nitrogen migrated from the first nitrogen-containing passivation layer, and the nitrogen is used to combine with the defective area on the surface of the silicon substrate to form a nitrogen-silicon bond to repair the defective area.

[0006] Optionally, the first nitrogen-containing passivation layer contains aluminum migrated from the first aluminum oxide layer.

[0007] Optionally, the first nitrogen-containing passivation layer includes: a first silicon nitride layer and / or a first silicon oxynitride layer.

[0008] Optionally, the first nitrogen-containing passivation layer contains hydrogen; The first aluminum oxide layer contains hydrogen migrated from the first nitrogen-containing passivation layer, and the hydrogen is used to form hydrogen passivation on the surface of the silicon substrate.

[0009] Optionally, along the thickness direction of the solar cell, the nitrogen concentration in the first aluminum oxide layer is lower in a portion closer to the silicon substrate.

[0010] Optionally, along the thickness direction of the solar cell, the concentration of aluminum in the first nitrogen-containing passivation layer is higher in a portion closer to the silicon substrate.

[0011] Optionally, along the thickness direction of the solar cell, the concentration of aluminum in the first aluminum oxide layer is lower in a portion closer to the silicon substrate.

[0012] Optionally, along the thickness direction of the solar cell, the oxygen concentration in the first aluminum oxide layer is higher in a portion closer to the silicon substrate.

[0013] Optionally, the first aluminum oxide layer is in contact with a surface of the silicon substrate; and the first nitrogen-containing passivation layer is in contact with a surface of the first aluminum oxide layer facing away from the silicon substrate.

[0014] Optionally, a surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer comprises aluminum.

[0015] Optionally, a side of the silicon substrate facing away from the first aluminum oxide layer includes: a first region and a second region; The first region includes: a first tunneling layer, a first doped polysilicon layer, a second aluminum oxide layer, and a second nitrogen-containing passivation layer stacked in sequence; The second region includes: a second tunneling layer, a second doped polysilicon layer, a third aluminum oxide layer, and a third nitrogen-containing passivation layer stacked in sequence.

[0016] Optionally, a first atomic mass percentage of aluminum element in the third nitrogen-containing passivation layer is greater than a second atomic mass percentage of aluminum element in the second nitrogen-containing passivation layer.

[0017] Optionally, the difference between the first atomic mass percentage and the second atomic mass percentage is greater than or equal to 0.3%.

[0018] Optionally, the first atomic mass accounts for 0.3% to 1%. The second atomic mass accounts for 0-0.1%.

[0019] Optionally, the side of the silicon substrate facing away from the first aluminum oxide layer includes: a third region and a fourth region; The third region includes: a third tunneling layer and a third doped polysilicon layer stacked in sequence; The fourth region includes: an intrinsic amorphous silicon layer and a doped amorphous silicon layer stacked in sequence, or an intrinsic amorphous silicon layer and a doped microcrystalline silicon layer stacked in sequence.

[0020] Optionally, the surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer further includes: one or more of a first silicon oxide layer and a silicon carbide layer.

[0021] Optionally, the first nitrogen-containing passivation layer includes: a second silicon nitride layer and a second silicon oxynitride layer; The side of the silicon substrate facing away from the first aluminum oxide layer comprises: a fourth tunneling layer, a third doped polysilicon layer, a fourth aluminum oxide layer, a third silicon nitride layer, a third silicon oxynitride layer, and a second silicon oxide layer stacked in sequence; The first aluminum oxide layer includes: a second silicon nitride layer, a second silicon oxynitride layer, and a third silicon oxide layer which are stacked in sequence.

[0022] Optionally, a first structural layer is provided on the first surface of the silicon substrate, and a second structural layer is provided on the second surface of the silicon substrate; The first structural layer includes: the first aluminum oxide layer and the first nitrogen-containing passivation layer; the first surface is a light-facing surface; the second surface is a backlight surface; the overall refractive index of the first structural layer is less than the overall refractive index of the second structural layer; and / or, The refractive index of the outermost film layer of the first structural layer is smaller than the refractive index of the outermost film layer of the second structural layer.

[0023] Optionally, the overall refractive index of the first structural layer is smaller than the overall refractive index of the second structural layer, and the difference between the overall refractive index of the first structural layer and the overall refractive index of the second structural layer is greater than 0.2; and / or, The refractive index of the outermost film layer of the first structure layer is smaller than the refractive index of the outermost film layer of the second structure layer, and the difference between the refractive index of the outermost film layer of the first structure layer and the refractive index of the outermost film layer of the second structure layer is greater than 0.4.

[0024] Optionally, the first nitrogen-containing passivation layer includes: a third silicon nitride layer and a third silicon oxynitride layer; The first structural layer comprises: the first aluminum oxide layer, the third silicon nitride layer, and the third silicon oxynitride layer stacked in sequence; The second structural layer includes: a fourth silicon nitride layer.

[0025] In the present invention, the first aluminum oxide layer is arranged in contact with the silicon substrate. At the interface between the silicon substrate and the first aluminum oxide layer, the nitrogen in the first aluminum oxide layer migrates from the first nitrogen-containing passivation layer. The nitrogen can reduce the interface state density, that is, the nitrogen element can fill the dangling bonds in the defective area on the surface of the silicon substrate, and realize the chemical passivation of the nitrogen-silicon bond, thereby reducing the formation of defective areas, reducing the defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in the defective areas, and increasing the open circuit voltage, which is conducive to the transmission of more carriers to the electrodes of the solar cell and out, thereby improving the photoelectric conversion efficiency of the solar cell.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of the structure of a solar cell according to an embodiment of the present invention; Figure 2 It is a schematic diagram of secondary ion mass spectrometry detection results of a solar cell described in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] 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 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.

[0030] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally a class, and the number of objects is not limited. For example, the first object can be one or more. In addition, the term "and / or" in the specification and claims is used to describe the association relationship of associated objects, indicating that three kinds of relationships can exist, for example, A and / or B can be represented: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the front and back associated objects are a kind of "or" relationship. In the embodiment of the present application, the term "multiple" refers to two or more, and other quantifiers are similar.

[0031] like Figure 1As shown, the present invention provides a solar cell, which includes: a silicon substrate 10, a first aluminum oxide layer 20 and a first nitrogen-containing passivation layer 30; the first aluminum oxide layer 20 is arranged on at least one surface of the silicon substrate 10, and the first nitrogen-containing passivation layer 30 is arranged on the first aluminum oxide layer 20; wherein the first aluminum oxide layer 20 contains nitrogen migrated from the first nitrogen-containing passivation layer 30, and the nitrogen is used to combine with the defective area on the surface of the silicon substrate 10 to form a nitrogen-silicon bond to repair the defective area.

[0032] Optionally, the first nitrogen-containing passivation layer 30 contains aluminum migrated from the first aluminum oxide layer 20 .

[0033] In the embodiment of the present invention, when preparing a solar cell, a passivation layer can be prepared on the front side of the silicon substrate 10. The passivation layer is used to reduce the recombination rate on the cell surface and improve the utilization rate of light. In addition, the passivation layer can also resist the erosion of external pollutants, thereby protecting the stability and efficiency of the cell during long-term use.

[0034] In an embodiment of the present invention, the passivation layer on the front side of the silicon substrate 10 may include a first aluminum oxide layer 20 and a first nitrogen-containing passivation layer 30 stacked in sequence, wherein the first aluminum oxide layer 20 may be in the form of a thin film, and aluminum oxide, as a passivation material, has a high density of fixed negative charges, can provide partial field passivation, and improve the passivation effect of the passivation anti-reflection layer, thereby reducing the recombination probability of carriers in the solar cell and improving the efficiency of the solar cell. The first nitrogen-containing passivation layer may specifically use a first silicon nitride layer and / or a first silicon oxynitride layer to achieve its passivation effect, because nitrogen can improve the thermal stability of the material, adapt to high-temperature processes, and help prepare the passivation layer. Nitrogen can also improve the stability of the material and enhance the reliability of the product after ultraviolet light irradiation.

[0035] Specifically, part of the aluminum elements in the first aluminum oxide layer of the embodiment of the present invention can migrate out, and these aluminum elements can migrate into the first nitrogen-containing passivation layer, so that the first nitrogen-containing passivation layer has aluminum migrated from the first aluminum oxide layer; in addition, the aluminum elements migrated into the first nitrogen-containing passivation layer will replace part of the original light elements in the first nitrogen-containing passivation layer, such as nitrogen elements, so that these replaced nitrogen elements migrate out from the first nitrogen-containing passivation layer and further flow into the first aluminum oxide layer, so that the first aluminum oxide layer has nitrogen migrated from the first nitrogen-containing passivation layer.

[0036] Furthermore, due to factors such as processing, there are defective areas on the surface of the silicon substrate, and the defective areas will affect the performance of the solar cell. The first aluminum oxide layer is arranged in contact with the silicon substrate. At the interface between the silicon substrate and the first aluminum oxide layer, the nitrogen in the first aluminum oxide layer (nitrogen migrated from the first nitrogen-containing passivation layer) can reduce the interface state density, that is, the nitrogen element can fill the dangling bonds in the defective areas on the surface of the silicon substrate, and realize chemical passivation of nitrogen-silicon (N-Si) bonds, thereby reducing the formation of defective areas, reducing the defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in the defective areas, and increasing the open circuit voltage, which is conducive to the transmission of more carriers to the electrodes of the solar cell and out, thereby improving the photoelectric conversion efficiency.

[0037] In addition, the first aluminum oxide layer has a high density of fixed negative charges, which is beneficial to improving the field passivation effect on the surface of the silicon substrate. The first aluminum oxide layer itself has a field passivation layer. After the aluminum migrated from the first aluminum oxide layer enters the first silicon nitride layer, because the aluminum itself carries a positive charge, the first silicon nitride layer also carries a positive charge, which can further enhance the electric field strength and improve the field passivation effect. Therefore, the passivation layer can further improve the photoelectric conversion efficiency of solar cells through the synergy of field passivation and chemical passivation.

[0038] Optionally, the first nitrogen-containing passivation layer includes: a first silicon nitride layer and / or a first silicon nitride oxide layer; wherein the first aluminum oxide layer contains: hydrogen migrated from the first nitrogen-containing passivation layer (in one case, the first nitrogen-containing passivation layer may include: a first silicon nitride layer and / or the first silicon nitride oxide layer), and the hydrogen is used to form hydrogen passivation on the surface of the silicon substrate.

[0039] In an embodiment of the present invention, the first aluminum oxide layer may contain: hydrogen migrated from the first silicon nitride layer and / or the first silicon oxynitride layer. This is because the raw materials for preparing silicon nitride or silicon oxynitride contain hydrogen-containing materials. The hydrogen migrated from the first silicon nitride layer and / or the first silicon oxynitride layer can passivate the dangling bonds on the surface of the silicon substrate well, thereby forming hydrogen passivation on the surface of the silicon substrate, thereby further improving the passivation effect of the passivation layer. The combination of nitrogen and hydrogen can also increase nitrogen-hydrogen bonds, reducing the risk of explosion of the first aluminum oxide layer caused by hydrogen overflow.

[0040] Reference Figure 2, which shows a schematic diagram of the secondary ion mass spectrometry (SIMS) detection results of a solar cell, which shows the result data obtained by SIMS detection of the stacked structure of silicon substrate + first aluminum oxide layer + first silicon nitride layer. The detection is to intercept a solar cell sample with this layer structure, and then bombard the sample surface with an ion beam, and detect the mass-to-charge ratio of the sputtered secondary ions with charge through a mass spectrometer to obtain the elemental characterization of the sample. Among them, the horizontal axis of the coordinate system in the schematic diagram represents the sputtering time (in seconds: S), and the vertical axis represents the response intensity of the detected element or ion group. The greater the response intensity, the higher the component content (concentration) of the element or ion group. In addition, the longer the sputtering time, the deeper the detected layer.

[0041] like Figure 2 As shown, on the right side of 740S, the sputtering time is long, the aluminum oxide strength value increases, and the silicon nitride strength value decreases, so that the boundary between the first silicon nitride layer and the first aluminum oxide layer can be clearly seen. In addition, on the left side of 740S, the aluminum strength value decreases, but does not disappear. It can be determined that part of the aluminum in the first aluminum oxide layer has migrated into the first silicon nitride layer; the aluminum strength value on the right side of 740S increases, and combined with the increase in the aluminum oxide strength value, it can be determined that it is the aluminum in the first aluminum oxide layer. Since the first aluminum oxide layer itself has a field passivation effect, after the aluminum migrated from the first aluminum oxide layer enters the first silicon nitride layer, because the aluminum itself is positively charged, the first silicon nitride layer is also positively charged, so the electric field strength can be strengthened to improve the field passivation effect.

[0042] In addition, when the sputtering time is about 840S, it can be clearly observed that the intensity values ​​of hydrogen, oxygen, nitrogen, and aluminum decrease, while the intensity value of silicon increases. At about 840S, a crossover point is formed, which can be understood as the interface between the first aluminum oxide layer and the silicon substrate. The silicon layer at this interface is more damaged and has more damaged dangling bonds, so the damaged area is filled with hydrogen, oxygen, nitrogen, etc. Hydrogen fills the damaged area to form hydrogen passivation, nitrogen combines with silicon to form a nitrogen-silicon bond, oxygen combines with silicon to form an oxygen-silicon bond, and they combine to form chemical passivation, which fully protects the damage at the silicon substrate interface of the solar cell, increases the passivation effect, and improves the photoelectric conversion efficiency.

[0043] Among them, the nitrogen at the interface is transferred from the nitrogen in the first silicon nitride layer; the hydrogen at the interface is transferred from the hydrogen in the first silicon nitride layer and the first aluminum oxide layer, because when the first silicon nitride layer and the first aluminum oxide layer are manufactured, the material source includes materials containing hydrogen elements; the oxygen at the interface is transferred from the oxygen in the aluminum oxide.

[0044] In one example, the preparation of a solar cell is described: First, the silicon substrate can be wet-polished and textured. Specifically, the silicon substrate is cleaned with chemical reagents, and then the residual chemical reagents are neutralized and cleaned with deionized water. After that, the silicon substrate is polished and textured with alkaline chemical reagents. After the textured silicon substrate, a pyramid texture surface with different crystal orientations is formed on the surface.

[0045] After wet polishing and texturing, the semiconductor layer can be prepared, and after the semiconductor layer is prepared, the first aluminum oxide layer and the first nitrogen-containing passivation layer on the front side of the silicon substrate can be prepared. The first aluminum oxide layer can be prepared using trimethylaluminum as the aluminum source and water as the oxygen source. During the preparation process, if you want to increase the concentration of aluminum, you can control the input of more aluminum source and less oxygen source. The concentration of aluminum can be controlled. The first nitrogen-containing passivation layer can be silicon nitride and / or silicon oxynitride. For example, the plasma enhanced chemical vapor deposition (PECVD) process can use plasma as the activation method for chemical vapor deposition, so that silane and ammonia can form silicon nitride under the conditions of plasma enhanced reaction.

[0046] Afterwards, electrodes are prepared to complete the preparation of the solar cell.

[0047] In summary, in the embodiment of the present invention, the first aluminum oxide layer is arranged in contact with the silicon substrate. Then, at the interface between the silicon substrate and the first aluminum oxide layer, the nitrogen in the first aluminum oxide layer that migrates from the first nitrogen-containing passivation layer can reduce the interface state density, that is, the nitrogen element can fill the dangling bonds in the defective area on the surface of the silicon substrate, and realize the chemical passivation of the nitrogen-silicon bond, thereby reducing the formation of defective areas, reducing the defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in the defective areas, and increasing the open circuit voltage, which is conducive to the transmission of more carriers to the electrodes of the solar cell and out, thereby improving the photoelectric conversion efficiency of the solar cell.

[0048] Optional, see Figure 1 Along the thickness direction x of the solar cell, the nitrogen concentration in the first aluminum oxide layer 20 closer to the silicon substrate 10 is lower.

[0049] In the embodiment of the present invention, along the thickness direction x of the solar cell, the concentration of nitrogen in the first aluminum oxide layer 20 closer to the silicon substrate 10 is lower, so that the nitrogen migrated into the first aluminum oxide layer 20 can improve the thermal stability of the material and adapt to the high temperature process. In addition, nitrogen in the first aluminum oxide layer 20 can improve the stability of the material and enhance the reliability of the product after ultraviolet light irradiation. In addition, nitrogen in the first aluminum oxide layer 20 can also increase the combination of nitrogen-hydrogen bonds (NH), reducing the risk of aluminum oxide film explosion caused by hydrogen overflow. Figure 2It can be seen that in the first aluminum oxide layer 20 , as the sputtering time increases, the intensity value of nitrogen gradually decreases, that is, the closer the first aluminum oxide layer 20 is to the silicon substrate 10 , the lower the nitrogen concentration is.

[0050] Optional, see Figure 1 Along the thickness direction x of the solar cell, the concentration of aluminum in the first nitrogen-containing passivation layer 30 closer to the silicon substrate 10 is higher.

[0051] In the embodiment of the present invention, refer to Figure 2 It can be seen that in the first nitrogen-containing passivation layer 30 (first silicon nitride layer), as the sputtering time increases, the intensity value of aluminum gradually increases, that is, the closer the first nitrogen-containing passivation layer 30 is to the silicon substrate 10 , the higher the concentration of aluminum is. Such phenomenon indicates that part of the aluminum element in the first aluminum oxide layer 20 can migrate to the first nitrogen-containing passivation layer 30 and replace part of the original nitrogen element in the first nitrogen-containing passivation layer 30, and the closer the part of the first nitrogen-containing passivation layer 30 is to the silicon substrate 10, the higher the concentration of aluminum received, and the farther the part is from the silicon substrate 10, the lower the concentration of aluminum. The replaced nitrogen element in the first nitrogen-containing passivation layer 30 migrates out of the first nitrogen-containing passivation layer 30 and further flows into the first aluminum oxide layer 20, so that the first aluminum oxide layer 20 has nitrogen migrated from the first nitrogen-containing passivation layer, so that the nitrogen in the first aluminum oxide layer 20 can reduce the interface state density, that is, the nitrogen element can fill the dangling bonds in the defective area on the surface of the silicon substrate, and realize the chemical passivation of the nitrogen-silicon (N-Si) bond, thereby reducing the formation of defective areas, reducing the defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in the defective areas, and increasing the open circuit voltage, which is conducive to more carriers being transmitted to the electrodes of the solar cell and transmitted out, thereby improving the photoelectric conversion efficiency.

[0052] Optional, see Figure 1 Along the thickness direction x of the solar cell, the concentration of aluminum in the first aluminum oxide layer 20 closer to the silicon substrate 10 is lower.

[0053] In the embodiment of the present invention, refer to Figure 2 It can be seen that in the first aluminum oxide layer 20, as the sputtering time increases, the aluminum concentration in the part closer to the silicon substrate 10 becomes lower. This phenomenon is achieved by a special process. For example, trimethyl aluminum can be used as an aluminum source and water can be used as an oxygen source to prepare the first aluminum oxide layer. During the preparation process, if the aluminum concentration is to be increased, more aluminum source can be input and less oxygen source can be input to achieve the control of aluminum concentration.

[0054] That is, in the first aluminum oxide layer 20, the aluminum concentration of the part closer to the silicon substrate 10 is made lower, and the oxygen concentration is made higher, so that the oxygen on the surface of the silicon substrate can be combined with the silicon bond (Si-O), fill the dangling bonds, reduce the density of dangling bonds on the surface of the silicon substrate, and improve the chemical passivation effect. In the first aluminum oxide layer 20, the aluminum concentration of the part away from the silicon substrate 10 is gradually made higher, and the oxygen concentration is made lower. The purpose of this is to facilitate the subsequent aluminum in the first aluminum oxide layer 20 to migrate more conveniently to the first nitrogen-containing passivation layer 30, thereby achieving a passivation effect.

[0055] Optional, see Figure 1 Along the thickness direction x of the solar cell, the oxygen concentration in the first aluminum oxide layer 20 closer to the silicon substrate 10 is higher.

[0056] In the embodiment of the present invention, refer to Figure 2 It can be seen that in the first aluminum oxide layer 20, as the sputtering time increases, the oxygen concentration in the part closer to the silicon substrate 10 is higher, that is, the oxygen content in the first aluminum oxide layer 20 closer to the surface of the silicon substrate is higher, forming an oxygen-silicon (O-Si) bond to provide chemical passivation. In addition, the large amount of fixed negative charge of aluminum oxide can play a good field passivation effect. Through the synergy of field passivation and chemical passivation, the photoelectric conversion efficiency can be further improved.

[0057] Optionally, the first aluminum oxide layer is in contact with a surface of the silicon substrate; and the first nitrogen-containing passivation layer is in contact with a surface of the first aluminum oxide layer facing away from the silicon substrate.

[0058] In the embodiment of the present invention, since the first aluminum oxide layer contacts a surface of the silicon substrate; the first nitrogen-containing passivation layer contacts the surface of the first aluminum oxide layer away from the silicon substrate, the aluminum in the first aluminum oxide layer can be more easily migrated to the first nitrogen-containing passivation layer, and the nitrogen in the first nitrogen-containing passivation layer can be more easily migrated to the first aluminum oxide layer, and the nitrogen migrated to the first aluminum oxide layer can more easily fill the dangling bonds in the defective area on the surface of the silicon substrate, realizing chemical passivation of nitrogen-silicon (N-Si) bonds, thereby reducing the formation of defective areas, reducing defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in defective areas, and increasing the open circuit voltage, which is conducive to more carriers being transmitted to the electrodes of the solar cell and transmitted out, thereby improving the photoelectric conversion efficiency.

[0059] Optionally, a surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer comprises aluminum.

[0060] In an embodiment of the present invention, the surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer has aluminum, that is, by adding a metal element (aluminum) to the passivation layer, the electric field generated by the fixed charge of the metal element itself is used to provide partial field passivation, thereby improving the passivation effect of the passivation layer, thereby reducing the recombination probability of carriers in the solar cell and improving the efficiency of the solar cell.

[0061] Optionally, the surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer further includes: one or more of a first silicon oxide layer and a silicon carbide layer.

[0062] In an embodiment of the present invention, the surface of the first nitrogen-containing passivation layer away from the first aluminum oxide also includes: one or more of a first silicon oxide layer and a silicon carbide layer, such as, a stacked structure of a first aluminum oxide layer + a first silicon nitride layer + a first silicon nitride oxide layer is formed on the surface of a silicon substrate; another example: a stacked structure of a first aluminum oxide layer + a first silicon nitride layer + a first silicon oxide layer is formed on the surface of a silicon substrate; another example: a stacked structure of a first aluminum oxide layer + a first silicon nitride layer + a first silicon carbide layer is formed on the surface of a silicon substrate.

[0063] Optionally, the first nitrogen-containing passivation layer includes: a third silicon nitride layer, a third silicon oxynitride layer; a first structural layer is provided on the first surface of the silicon substrate, and the first structural layer includes: a first aluminum oxide layer, a third silicon nitride layer, a third silicon oxynitride layer and a fourth silicon oxide layer stacked in sequence on the first surface; a second structural layer is provided on the second surface of the silicon substrate, and the second structural layer includes: a fourth silicon nitride layer, a fourth silicon oxynitride layer and a fifth silicon oxide layer stacked in sequence on the second surface; in the first structural layer and the second structural layer, the refractive index of the portion farther away from the silicon substrate is smaller.

[0064] In the embodiment of the present invention, the first structural layer on the front side of the silicon substrate may be a stacked structure of a first aluminum oxide layer + a third silicon nitride layer + a third silicon oxynitride layer + a fourth silicon oxide layer, and the second structural layer on the back side of the silicon substrate may be a stacked structure of a fourth silicon nitride layer + a fourth silicon oxynitride layer + a fifth silicon oxide layer. In addition, in the first structural layer and the second structural layer, the refractive index of the part farther away from the silicon substrate is smaller.

[0065] In one implementation, the refractive index of the third silicon nitride layer and the fourth silicon nitride layer can be 1.9-2.2, specifically, the refractive index of the third silicon nitride layer and the fourth silicon nitride layer can be any value among 1.9, 2.0, 2.1, and 2.2; the refractive index of the third silicon oxynitride layer and the fourth silicon oxynitride layer can be 1.7-1.9, specifically, the refractive index of the third silicon oxynitride layer and the fourth silicon oxynitride layer can be any value among 1.7, 1.8, and 1.9; the refractive index of the fourth silicon oxide layer and the fifth silicon oxide layer is closer to air, and the refractive index of the fourth silicon oxide layer and the fifth silicon oxide layer can be 1.2-1.6, specifically, the refractive index of the fourth silicon oxide layer and the fifth silicon oxide layer can be any value among 1.2, 1.3, 1.4, 1.5, and 1.6.

[0066] Optionally, a first structural layer is provided on the first surface of the silicon substrate, and a second structural layer is provided on the second surface of the silicon substrate; The first structural layer includes: the first aluminum oxide layer and the first nitrogen-containing passivation layer; the first surface is a light-facing surface; the second surface is a backlight surface; the overall refractive index of the first structural layer is less than the overall refractive index of the second structural layer; and / or, The refractive index of the outermost film layer of the first structural layer is smaller than the refractive index of the outermost film layer of the second structural layer.

[0067] Optionally, the overall refractive index of the first structural layer is smaller than the overall refractive index of the second structural layer, and the difference between the overall refractive index of the first structural layer and the overall refractive index of the second structural layer is greater than 0.2; and / or, The refractive index of the outermost film layer of the first structure layer is smaller than the refractive index of the outermost film layer of the second structure layer, and the difference between the refractive index of the outermost film layer of the first structure layer and the refractive index of the outermost film layer of the second structure layer is greater than 0.4.

[0068] Optionally, the first nitrogen-containing passivation layer includes: a third silicon nitride layer and a third silicon nitride oxide layer; the first structural layer includes: the first aluminum oxide layer, the third silicon nitride layer and the third silicon nitride oxide layer stacked in sequence; the second structural layer includes: a fourth silicon nitride layer and a fourth silicon nitride oxide layer stacked in sequence.

[0069] Optionally, the first nitrogen-containing passivation layer includes: a third silicon nitride layer and a third silicon oxynitride layer; the first structural layer includes: the first aluminum oxide layer, the third silicon nitride layer, and the third silicon oxynitride layer stacked in sequence; and the second structural layer includes: a fourth silicon nitride layer.

[0070] For example, in one implementation, the proportion of short-wavelength light on the light-facing side (such as the first side of the silicon substrate) of the solar cell is large compared to the backlight side (such as the second side of the silicon substrate), while the proportion of long-wavelength light on the backlight side of the solar cell is large compared to the light-facing side. Therefore, the overall refractive index of the passivation anti-reflection film (such as the first structural layer) on the light-facing side is set to be smaller than the passivation anti-reflection film (such as the second structural layer) on the backlight side, which is beneficial to reduce the reflection of short-wavelength light on the light-facing side and increase the short-wavelength light entering the silicon substrate, thereby improving the efficiency of the solar cell. For example, it is preferred that the overall refractive index of the passivation anti-reflection film on the light-facing side is smaller than that of the passivation anti-reflection film on the backlight side by more than 0.2.

[0071] In addition, the refractive index of the outermost film layer of the passivation anti-reflection layer on the light side is set to be smaller than the refractive index of the outermost film layer of the passivation anti-reflection layer on the back side. For example, the refractive index of the outermost film layer of the passivation anti-reflection layer on the light side is smaller than the refractive index of the outermost film layer of the passivation anti-reflection layer on the back side by more than 0.4, and can be 0.4, 0.45, 0.5, 0.55, 0.6. In some embodiments, the outermost film layer of the passivation anti-reflection layer on the light side can be selected from silicon oxynitride or silicon oxide with a low refractive index, while the outermost film layer of the passivation anti-reflection layer on the back side can be selected from silicon nitride with a relatively high refractive index.

[0072] Optionally, in one implementation, an embodiment of the present invention can be applied to a TBC (TOPCon-BC, BC stands for back contact) battery, that is, the side of the silicon substrate facing away from the first aluminum oxide layer includes: a first region and a second region; the first region includes: a first tunneling layer, a first doped polysilicon layer, a second aluminum oxide layer, and a second nitrogen-containing passivation layer stacked in sequence; the second region includes: a second tunneling layer, a second doped polysilicon layer, a third aluminum oxide layer, and a third nitrogen-containing passivation layer stacked in sequence.

[0073] Among them, the second aluminum oxide layer and the second nitrogen-containing passivation layer can be formed by a process at one time, and the third aluminum oxide layer and the third nitrogen-containing passivation layer can be formed by a process at one time. The first doped polysilicon layer can be an n-type polysilicon layer, and the second doped polysilicon layer can be a p-type polysilicon layer; or the first doped polysilicon layer can be a p-type polysilicon layer, and the second doped polysilicon layer can be an n-type polysilicon layer. The aluminum oxide layer and the nitrogen-containing passivation layer on the front and back sides of the TBC battery can achieve the effects described in the above embodiments.

[0074] It should be noted that the second aluminum oxide layer, the second nitrogen-containing passivation layer, the third aluminum oxide layer and the third nitrogen-containing passivation layer on the side of the silicon substrate away from the first aluminum oxide layer can adopt the design of the first aluminum oxide layer and the first nitrogen-containing passivation layer in the above embodiment, or can adopt other designs, and the embodiment of the present invention is not limited to this.

[0075] Optionally, based on the application of the embodiment of the present invention to a TBC battery, a first atomic mass ratio of the aluminum element in the third nitrogen-containing passivation layer is greater than a second atomic mass ratio of the aluminum element in the second nitrogen-containing passivation layer.

[0076] Optionally, the difference between the first atomic mass percentage and the second atomic mass percentage is greater than or equal to 0.3%.

[0077] Optionally, the first atomic mass accounts for 0.3% to 1%, and the second atomic mass accounts for 0 to 0.1%.

[0078] Optionally, in another implementation, an embodiment of the present invention can be applied to a hybrid BC (BC stands for back contact) battery, that is, the side of the silicon substrate facing away from the first aluminum oxide layer includes: a third region and a fourth region; the third region includes: a third tunneling layer and a third doped polycrystalline silicon layer stacked in sequence; the fourth region includes: an intrinsic amorphous silicon layer and a doped amorphous silicon layer stacked in sequence, or an intrinsic amorphous silicon layer and a doped microcrystalline silicon layer stacked in sequence.

[0079] In the embodiment of the present invention, the third doped polysilicon layer may be an n-type polysilicon layer, and the amorphous or microcrystalline silicon layer may be a p-type amorphous or microcrystalline silicon layer.

[0080] Optionally, in another implementation, an embodiment of the present invention can be applied to a tunnel oxide passivated contact TOPCon (TOPCon, Tunnel Oxide Passivated Contact) battery, that is, the first nitrogen-containing passivation layer includes: a second silicon nitride layer, a second silicon oxynitride layer; the side of the silicon substrate away from the first aluminum oxide layer includes: a fourth tunneling layer, a third doped polysilicon layer, a fourth aluminum oxide layer, a third silicon nitride layer, a third silicon oxynitride layer, and a second silicon oxide layer stacked in sequence.

[0081] The first aluminum oxide layer includes: a second silicon nitride layer, a second silicon oxynitride layer, and a third silicon oxide layer which are stacked in sequence.

[0082] It should be noted that the silicon substrate is away from the fourth aluminum oxide layer, the third silicon nitride layer, and the third silicon oxynitride layer. The design of the first aluminum oxide layer and the first nitrogen-containing passivation layer (including the first silicon nitride layer and the first silicon oxynitride layer) in the above embodiment can be adopted, or other designs can be adopted. The embodiment of the present invention is not limited to this.

[0083] In summary, in the embodiment of the present invention, the first aluminum oxide layer is arranged in contact with the silicon substrate. Then, at the interface between the silicon substrate and the first aluminum oxide layer, the nitrogen in the first aluminum oxide layer migrates from the first nitrogen-containing passivation layer. The nitrogen can reduce the interface state density, that is, the nitrogen element can fill the dangling bonds in the defective area on the surface of the silicon substrate, and realize the chemical passivation of the nitrogen-silicon bond, thereby reducing the formation of defective areas, reducing the defective areas on the surface of the silicon substrate, reducing the aggregation of carriers in the defective areas, and increasing the open circuit voltage, which is conducive to the transmission of more carriers to the electrodes of the solar cell and out, thereby improving the photoelectric conversion efficiency of the solar cell.

[0084] The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, rather than to describe a specific order or precedence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0085] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: The solar cell comprises: A silicon substrate, a first aluminum oxide layer, and a first nitrogen-containing passivation layer; The first aluminum oxide layer is disposed on at least one surface of the silicon substrate, and the first nitrogen-containing passivation layer is disposed on the first aluminum oxide layer; The first aluminum oxide layer contains nitrogen migrated from the first nitrogen-containing passivation layer, and the nitrogen is used to combine with the defective area on the surface of the silicon substrate to form a nitrogen-silicon bond to repair the defective area.

2. The solar cell according to claim 1, wherein: The first nitrogen-containing passivation layer contains aluminum migrated from the first aluminum oxide layer.

3. The solar cell according to claim 1, wherein: The first nitrogen-containing passivation layer comprises: a first silicon nitride layer and / or a first silicon oxynitride layer.

4. The solar cell according to claim 1, wherein: The first nitrogen-containing passivation layer has hydrogen therein; The first aluminum oxide layer contains hydrogen migrated from the first nitrogen-containing passivation layer, and the hydrogen is used to form hydrogen passivation on the surface of the silicon substrate.

5. The solar cell according to claim 1, wherein: Along the thickness direction of the solar cell, the nitrogen concentration of a portion of the first aluminum oxide layer closer to the silicon substrate is lower.

6. The solar cell according to claim 1, wherein: Along the thickness direction of the solar cell, the concentration of aluminum in the first nitrogen-containing passivation layer is higher at a location closer to the silicon substrate.

7. The solar cell according to claim 1, wherein: Along the thickness direction of the solar cell, the concentration of aluminum in the first aluminum oxide layer is lower at a portion closer to the silicon substrate.

8. The solar cell according to claim 1, wherein: Along the thickness direction of the solar cell, the oxygen concentration in the first aluminum oxide layer is higher at a portion closer to the silicon substrate.

9. The solar cell according to any one of claims 1 to 8, characterized in that: The first aluminum oxide layer is in contact with one surface of the silicon substrate; and the first nitrogen-containing passivation layer is in contact with a surface of the first aluminum oxide layer facing away from the silicon substrate.

10. The solar cell according to claim 1, wherein: A surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer comprises aluminum.

11. The solar cell according to claim 1, wherein: The side of the silicon substrate facing away from the first aluminum oxide layer includes: a first region and a second region; The first region includes: a first tunneling layer, a first doped polysilicon layer, a second aluminum oxide layer, and a second nitrogen-containing passivation layer stacked in sequence; The second region includes: a second tunneling layer, a second doped polysilicon layer, a third aluminum oxide layer, and a third nitrogen-containing passivation layer stacked in sequence.

12. The solar cell according to claim 11, wherein: A first atomic mass ratio of aluminum element in the third nitrogen-containing passivation layer is greater than a second atomic mass ratio of aluminum element in the second nitrogen-containing passivation layer.

13. The solar cell according to claim 12, characterized in that: The difference between the first atomic mass percentage and the second atomic mass percentage is greater than or equal to 0.3%.

14. The solar cell according to claim 12, characterized in that: The first atomic mass accounts for 0.3% to 1%. The second atomic mass accounts for 0-0.1%.

15. The solar cell according to claim 1, characterized in that The side of the silicon substrate facing away from the first aluminum oxide layer includes: a third region and a fourth region; The third region includes: a third tunneling layer and a third doped polysilicon layer stacked in sequence; The fourth region includes: an intrinsic amorphous silicon layer and a doped amorphous silicon layer stacked in sequence, or an intrinsic amorphous silicon layer and a doped microcrystalline silicon layer stacked in sequence.

16. The solar cell according to claim 1, characterized in that The surface of the first nitrogen-containing passivation layer facing away from the first aluminum oxide layer further includes: one or more of a first silicon oxide layer and a silicon carbide layer.

17. The solar cell according to claim 1, characterized in that The first nitrogen-containing passivation layer includes: a second silicon nitride layer and a second silicon oxynitride layer; The side of the silicon substrate facing away from the first aluminum oxide layer comprises: a fourth tunneling layer, a third doped polysilicon layer, a fourth aluminum oxide layer, a third silicon nitride layer, a third silicon oxynitride layer, and a second silicon oxide layer stacked in sequence; The first aluminum oxide layer includes: a second silicon nitride layer, a second silicon oxynitride layer, and a third silicon oxide layer which are stacked in sequence.

18. The solar cell according to claim 1, characterized in that The first surface of the silicon substrate is provided with a first structural layer, and the second surface of the silicon substrate is provided with a second structural layer; The first structural layer includes: the first aluminum oxide layer and the first nitrogen-containing passivation layer; the first surface is a light-facing surface; the second surface is a backlight surface; the overall refractive index of the first structural layer is less than the overall refractive index of the second structural layer; and / or, The refractive index of the outermost film layer of the first structural layer is smaller than the refractive index of the outermost film layer of the second structural layer.

19. The solar cell according to claim 18, characterized in that The overall refractive index of the first structural layer is smaller than the overall refractive index of the second structural layer, and the difference between the overall refractive index of the first structural layer and the overall refractive index of the second structural layer is greater than 0.2; and / or, The refractive index of the outermost film layer of the first structure layer is smaller than the refractive index of the outermost film layer of the second structure layer, and the difference between the refractive index of the outermost film layer of the first structure layer and the refractive index of the outermost film layer of the second structure layer is greater than 0.

4.

20. The solar cell according to claim 18, characterized in that The first nitrogen-containing passivation layer includes: a third silicon nitride layer and a third silicon oxynitride layer; The first structural layer comprises: the first aluminum oxide layer, the third silicon nitride layer, and the third silicon oxynitride layer stacked in sequence; The second structural layer includes: a fourth silicon nitride layer.

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