Solar cell and photovoltaic module

Abstract

The utility model discloses a solar cell and a photovoltaic assembly, the solar cell comprises a silicon substrate, an intrinsic amorphous silicon layer and an intrinsic silicon oxide layer, the intrinsic amorphous silicon layer is arranged on one side of the silicon substrate, and the intrinsic silicon oxide layer is arranged between the intrinsic amorphous silicon layer and the silicon substrate. The intrinsic silicon oxide layer is arranged between the silicon substrate and the intrinsic amorphous silicon layer, the intrinsic amorphous silicon layer contains a large number of Si-H bonds, after ultraviolet irradiation, the Si-H bonds can be broken, hydrogen atoms can be diffused to the silicon substrate, the intrinsic silicon oxide can prevent the hydrogen atoms from being diffused to the silicon substrate, and the intrinsic silicon oxide can prevent the hydrogen atoms from being diffused to the silicon substrate. In this way, hydrogen atoms can be prevented from gathering on the surface of the silicon substrate to cause passivation performance degradation, the risk of ultraviolet attenuation can be reduced, the intrinsic silicon oxide layer can replace passivation of part of the intrinsic amorphous silicon layer, the thickness of the amorphous silicon layer can be reduced, and the service life of the amorphous silicon layer is prolonged. The risks of current short circuit and increase of ultraviolet attenuation caused by parasitic absorption due to an over-thick amorphous silicon layer are avoided, and the reliability of the solar cell can be further improved.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module. Background Technology

[0002] Currently, the amorphous silicon passivation layer in back-contact heterojunction solar cells is quite sensitive to ultraviolet light. Because the amorphous silicon passivation layer contains a large number of silicon-hydrogen bonds, ultraviolet light with a peak wavelength of 365nm will destroy the silicon-hydrogen bonds. This will reduce the hydrogen content in intrinsic and doped amorphous and microcrystalline silicon, as well as the material performance and passivation performance of the cell due to long-term exposure to ultraviolet light, resulting in a decrease in the power of the solar cell and a decrease in reliability.

[0003] In related technologies, to address the issue of UV degradation, batteries often employ material combinations and component process designs, such as light-converting adhesive films, during the encapsulation process. This converts high-energy short-wavelength UV light into low-energy medium-to-long-wavelength light to reduce the UV portion reaching the cell surface. This involves placing a silicon nitride film layer on the cell surface. While this reduces reflection and improves cell efficiency, it significantly reduces passivation performance after UV degradation, failing to improve UV degradation. Furthermore, intrinsic amorphous silicon films contain numerous Si-H bonds, which break under UV irradiation. H atoms diffuse to the silicon substrate surface, increasing the number of dangling bonds and carrier recombination, thus failing to reduce the passivation performance of intrinsic amorphous silicon films. Utility Model Content

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to provide a solar cell that can reduce ultraviolet radiation reaching the cell surface, block the migration of hydrogen atoms in amorphous silicon, thereby preventing the passivation performance degradation of the silicon substrate and improving the ultraviolet radiation degradation of the solar cell.

[0005] This utility model further proposes a photovoltaic module.

[0006] The solar cell according to the present invention includes: a silicon substrate, an intrinsic amorphous silicon layer, and an intrinsic silicon oxide layer, wherein the intrinsic amorphous silicon layer is disposed on one side of the silicon substrate, and the intrinsic silicon oxide layer is disposed between the intrinsic amorphous silicon layer and the silicon substrate.

[0007] According to the present invention, the solar cell has an intrinsic silicon oxide layer between a silicon substrate and an intrinsic amorphous silicon layer. The intrinsic amorphous silicon layer contains a large number of Si-H bonds. After ultraviolet irradiation, the Si-H bonds break, and hydrogen atoms diffuse to the silicon substrate. The intrinsic silicon oxide can prevent hydrogen atoms from diffusing to the silicon substrate, thus avoiding the accumulation of hydrogen atoms on the surface of the silicon substrate, which would lead to passivation degradation. This reduces the risk of ultraviolet degradation. Moreover, the intrinsic silicon oxide layer can replace part of the passivation of the intrinsic amorphous silicon layer, thereby reducing the thickness of the amorphous silicon layer. This avoids the parasitic absorption problems caused by an excessively thick amorphous silicon layer, which could lead to current short circuits and increased risk of ultraviolet degradation, thereby improving the reliability of the solar cell.

[0008] In some examples of this utility model, the thickness of the intrinsic amorphous silicon layer is d1, and d1 satisfies the relationship: 3nm≤d1≤5nm; the thickness of the intrinsic silicon oxide layer is d2, and d2 satisfies the relationship: 0.5nm≤d2≤2nm.

[0009] In some examples of this invention, the solar cell further includes: a plurality of antireflection layers, wherein the plurality of antireflection layers are disposed on the side of the intrinsic amorphous silicon layer away from the intrinsic silicon oxide layer and are stacked in a direction away from the intrinsic silicon oxide layer, and at least two of the antireflection layers have different refractive indices.

[0010] In some examples of this invention, the refractive index of the plurality of antireflective layers decreases in the direction away from the intrinsic silicon oxide layer.

[0011] In some examples of this utility model, the plurality of antireflection layers include: a first silicon nitride layer, a second silicon nitride layer and a third silicon nitride layer, wherein the first silicon nitride layer is disposed on the side of the intrinsic amorphous silicon layer away from the intrinsic silicon oxide layer, the second silicon nitride layer is disposed on the side of the first silicon nitride layer away from the intrinsic amorphous silicon layer, and the third silicon nitride layer is disposed on the side of the second silicon nitride layer away from the first silicon nitride layer.

[0012] In some examples of this utility model, the refractive index of the first silicon nitride layer is n1, the refractive index of the second silicon nitride layer is n2, and the refractive index of the third silicon nitride layer is n3. n1, n2, and n3 satisfy the relationship: n1 > n2 > n3.

[0013] In some examples of this utility model, n1 satisfies the relationship: 2.2 < n1 ≤ 2.4; n2 satisfies the relationship: 2.0 < n2 ≤ 2.2; n3 satisfies the relationship: 1.8 < n3 ≤ 2.0.

[0014] In some examples of this utility model, the thickness of the first silicon nitride layer is d3, and d3 satisfies the relationship: 15nm≤d3≤30nm; and / or the thickness of the second silicon nitride layer is d4, and d4 satisfies the relationship: 20nm≤d4≤30nm; and / or the thickness of the third silicon nitride layer is d5, and d5 satisfies the relationship: 10nm≤d5≤20nm.

[0015] In some examples of this utility model, the refractive index of the plurality of antireflection layers is n4, and n4 satisfies the relationship: 2.0≤n4≤2.1; and / or the total thickness of the plurality of antireflection layers is d6, and d6 satisfies the relationship: 75nm≤d6≤85nm.

[0016] The photovoltaic module according to this utility model includes: the solar cell described above.

[0017] Compared with existing technologies, this invention employs an intrinsic silicon oxide layer placed between a silicon substrate and an intrinsic amorphous silicon layer. The intrinsic amorphous silicon layer contains a large number of Si-H bonds. After ultraviolet irradiation, these Si-H bonds break, and hydrogen atoms diffuse to the silicon substrate. The intrinsic silicon oxide can prevent hydrogen atoms from diffusing to the silicon substrate, thus avoiding the accumulation of hydrogen atoms on the surface of the silicon substrate that would lead to passivation degradation. This reduces the risk of ultraviolet degradation. Furthermore, the intrinsic silicon oxide layer can replace part of the passivation of the intrinsic amorphous silicon layer, thereby reducing the thickness of the amorphous silicon layer. This avoids the parasitic absorption problems caused by an excessively thick amorphous silicon layer, which could lead to current short circuits and increased risk of ultraviolet degradation, thereby improving the reliability of the solar cell.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0020] Figure 1 This is a partial structural schematic diagram of a solar cell according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a partial structure of the antireflective layer.

[0022] Figure label:

[0023] 100. Solar cells;

[0024] 10. Silicon substrate; 11. Textured surface; 20. Intrinsic amorphous silicon layer; 30. Intrinsic silicon oxide layer; 40. Antireflective layer; 41. First silicon nitride layer; 42. Second silicon nitride layer; 43. Third silicon nitride layer; 50. Boron-doped microcrystalline silicon layer; 60. Phosphorus-doped microcrystalline silicon layer; 70. Transparent conductive oxide; 80. Silver positive electrode; 90. Silver negative electrode. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0026] The following is for reference. Figure 1 and Figure 2 A solar cell 100 according to an embodiment of the present invention is described, which is used in a photovoltaic module.

[0027] like Figure 1 As shown, the solar cell 100 according to the present invention includes: a silicon substrate 10, an intrinsic amorphous silicon layer 20 and an intrinsic silicon oxide layer 30. The intrinsic amorphous silicon layer 20 is disposed on one side of the silicon substrate 10, and the intrinsic silicon oxide layer 30 is disposed between the intrinsic amorphous silicon layer 20 and the silicon substrate 10.

[0028] It is understood that the silicon substrate 10, the intrinsic amorphous silicon layer 20, and the intrinsic silicon oxide layer 30 constitute the main structure of the solar cell 100. The silicon substrate 10 can be made of monocrystalline silicon, which can ensure the photoelectric conversion efficiency, stability, and durability of the silicon substrate 10. At least one side of the silicon substrate 10 forms a textured surface 11, which can reduce reflection loss, improve the photoelectric conversion efficiency of the silicon substrate 10, enhance electrical performance, reduce the surface recombination rate of the silicon substrate 10, and improve the anti-fouling ability of the silicon substrate 10. The intrinsic amorphous silicon layer 20 is disposed on one side of the textured surface 11, and the intrinsic silicon oxide layer 30 is inserted between the intrinsic amorphous silicon layer 20 and the silicon substrate 10, that is, the intrinsic amorphous silicon layer 20, the intrinsic silicon oxide layer 30, and the silicon substrate 10 are stacked sequentially.

[0029] The intrinsic amorphous silicon layer 20 contains a large number of Si-H bonds. Under ultraviolet irradiation, the Si-H bonds break, and hydrogen ions diffuse. The intrinsic silicon oxide layer 30 can block the diffusion of hydrogen ions to the surface of the silicon substrate 10. This can prevent hydrogen atoms from accumulating on the surface of the silicon substrate 10 and causing passivation performance degradation, thereby reducing the risk of ultraviolet aging. Moreover, the intrinsic silicon oxide layer 30 has excellent passivation performance. The intrinsic silicon oxide layer 30 can replace part of the intrinsic amorphous silicon layer 20, which can reduce the thickness of the intrinsic amorphous silicon layer 20. An excessively thick intrinsic amorphous silicon layer 20 will increase the risk of ultraviolet aging, thereby improving the reliability of the solar cell 100.

[0030] Therefore, by setting an intrinsic silicon oxide layer 30 between the silicon substrate 10 and the intrinsic amorphous silicon layer 20, the intrinsic amorphous silicon layer 20 contains a large number of Si-H bonds. After ultraviolet irradiation, the Si-H bonds will break, and hydrogen atoms will diffuse to the silicon substrate 10. The intrinsic silicon oxide can prevent hydrogen atoms from diffusing to the silicon substrate 10. This can prevent hydrogen atoms from accumulating on the surface of the silicon substrate 10 and causing passivation performance degradation, thereby reducing the risk of ultraviolet degradation. Moreover, the intrinsic silicon oxide layer 30 can replace part of the passivation of the intrinsic amorphous silicon layer 20, thereby reducing the thickness of the amorphous silicon layer. This avoids the problem of parasitic absorption caused by an excessively thick amorphous silicon layer, which can lead to current short circuits and increase the risk of ultraviolet degradation, thereby improving the reliability of the solar cell 100.

[0031] Optionally, the thickness of the intrinsic amorphous silicon layer 20 is d1, where d1 satisfies the relationship: 3nm ≤ d1 ≤ 5nm. That is, the thickness of the intrinsic amorphous silicon layer 20 must be within a reasonable range. If the thickness is less than 3nm, the intrinsic amorphous silicon layer 20 cannot guarantee a sufficiently high light absorption rate. If the thickness is greater than 5nm, the transport path of charge carriers within the intrinsic amorphous silicon layer 20 will be too long, leading to carrier recombination losses. If the thickness is within a reasonable range, not only can a sufficiently high light absorption rate be guaranteed, but carrier recombination losses due to excessively long transport paths can also be reduced. For example, the thickness of the intrinsic amorphous silicon layer 20 can be 3nm, 4nm, or 5nm, with the specific value chosen based on the actual situation.

[0032] The thickness of the intrinsic silicon oxide layer 30 is d2, where d2 satisfies the relationship: 0.5nm ≤ d2 ≤ 2nm. This means the thickness of the intrinsic silicon oxide layer 30 must be within a reasonable range. If the thickness is less than 0.5nm, it will not effectively isolate the diffusion of hydrogen atoms in the intrinsic amorphous silicon layer 20, causing hydrogen atoms to contact the surface of the silicon substrate 10, thus degrading the passivation performance of the silicon substrate 10. If the thickness is greater than 2nm, ultraviolet light will enter the silicon substrate 10, reducing its photoelectric conversion efficiency. If the thickness is within a reasonable range, it can effectively block the diffusion of hydrogen atoms in the intrinsic amorphous silicon layer 20 while maintaining the photoelectric conversion efficiency of the silicon substrate 10. For example, the thickness of the intrinsic silicon oxide layer 30 can be 0.5nm, 1nm, or 1.5nm, with the specific value chosen based on the actual situation.

[0033] In addition, such as Figure 1As shown, the solar cell 100 further includes: a plurality of antireflection layers 40, which are disposed on the side of the intrinsic amorphous silicon layer 20 away from the intrinsic silicon oxide layer 30 and stacked in the direction away from the intrinsic silicon oxide layer 30, and at least two antireflection layers 40 have different refractive indices.

[0034] It is understandable that multiple antireflection layers 40 are disposed on one side of the intrinsic amorphous silicon layer 20, that is, multiple antireflection layers 40, intrinsic amorphous silicon layer 20, intrinsic silicon oxide layer 30 and silicon substrate 10 are stacked sequentially. Multiple antireflection layers 40 can reduce the reflection loss of sunlight on the surface of solar cell 100, thereby improving the light energy absorption efficiency and photoelectric conversion efficiency of solar cell 100. Moreover, at least two antireflection layers 40 have different refractive indices, which can reduce the amount of ultraviolet light reaching silicon substrate 10, thereby reducing the amount of ultraviolet light reaching silicon substrate 10, and further reducing the diffusion of hydrogen atoms in intrinsic amorphous silicon layer 20.

[0035] Specifically, the refractive index of the multiple antireflection layers 40 decreases in the direction away from the intrinsic silicon oxide layer 30. That is, the refractive index of the multiple antireflection layers 40 gradually decreases from the proximity to the intrinsic silicon oxide layer 30 to the distance from the intrinsic silicon oxide layer 30. This allows sunlight to first irradiate the antireflection layer 40 with the lower refractive index and then the antireflection layer 40 with the higher refractive index. This makes the refractive index change experienced by sunlight when irradiating each antireflection layer 40 more gradual and reduces the reflection of sunlight on each antireflection layer 40. In turn, it can reduce the reflection loss of sunlight and maximize the transmittance of sunlight.

[0036] Among them, such as Figure 2 As shown, the plurality of antireflection layers 40 include: a first silicon nitride layer 41, a second silicon nitride layer 42, and a third silicon nitride layer 43. The first silicon nitride layer 41 is disposed on the side of the intrinsic amorphous silicon layer 20 away from the intrinsic silicon oxide layer 30, the second silicon nitride layer 42 is disposed on the side of the first silicon nitride layer 41 away from the intrinsic amorphous silicon layer 20, and the third silicon nitride layer 43 is disposed on the side of the second silicon nitride layer 42 away from the first silicon nitride layer 41.

[0037] In other words, the first silicon nitride layer 41, the second silicon nitride layer 42, and the third silicon nitride layer 43 constitute the main structure of the antireflection layer 40. The first silicon nitride layer 41 is disposed on the side of the intrinsic amorphous silicon layer 20 away from the intrinsic silicon oxide layer 30, so that the first silicon nitride layer 41, the intrinsic amorphous silicon layer 20, the intrinsic silicon oxide layer 30, and the silicon substrate 10 can be sequentially stacked. The second silicon nitride layer 42 is disposed on the side of the first silicon nitride layer 41 away from the intrinsic amorphous silicon layer 20. On one side, the second silicon nitride layer 42, the first silicon nitride layer 41, the intrinsic amorphous silicon layer 20, the intrinsic silicon oxide layer 30, and the silicon substrate 10 are stacked sequentially. The third silicon nitride layer 43 is disposed on the side of the second silicon nitride layer 42 away from the first silicon nitride layer 41, so that the third silicon nitride layer 43, the second silicon nitride layer 42, the first silicon nitride layer 41, the intrinsic amorphous silicon layer 20, the intrinsic silicon oxide layer 30, and the silicon substrate 10 are stacked sequentially.

[0038] The silicon nitride layer can reduce the reflection loss of sunlight on the surface of the solar cell 100, improve the absorption efficiency of the solar cell 100, and enhance the energy conversion efficiency of the solar cell 100. It can also effectively passivate the intrinsic amorphous silicon layer 20, reduce dangling bonds and surface state density, thereby reducing the surface recombination rate of the intrinsic amorphous silicon layer 20, extending the effective lifetime of charge carriers, and thus improving the performance of the solar cell 100.

[0039] The first silicon nitride layer 41 has a refractive index of n1, the second silicon nitride layer 42 has a refractive index of n2, and the third silicon nitride layer 43 has a refractive index of n3. n1, n2, and n3 satisfy the relationship: n1 > n2 > n3.

[0040] Understandably, the refractive indices of the first silicon nitride layer 41, the second silicon nitride layer 42, and the third silicon nitride layer 43 are different. That is, the refractive indices of the first silicon nitride layer 41, the second silicon nitride layer 42, and the third silicon nitride layer 43 gradually decrease from near the intrinsic silicon oxide layer 30 to far away from the intrinsic silicon oxide layer 30. This allows sunlight to first irradiate the third silicon nitride layer 43, which has a lower refractive index, and then sequentially irradiate the second silicon nitride layer 42 and the first silicon nitride layer 41, which have gradually higher refractive indices. This makes the refractive index change experienced by sunlight when irradiating the third silicon nitride layer 43, the second silicon nitride layer 42, and the first silicon nitride layer 41 more gradual, and reduces the reflection of sunlight on the first silicon nitride layer 41, the second silicon nitride layer 42, and the third silicon nitride layer 43. In this way, the reflection loss of sunlight can be reduced, and the transmittance of sunlight can be maximized.

[0041] Optionally, n1 satisfies the relationship: 2.2 < n1 ≤ 2.4. That is, the refractive index of the first silicon nitride layer 41 must be within a reasonable range. If the refractive index of the first silicon nitride layer 41 is less than 2.2, it will result in an inability to effectively reduce reflection loss between sunlight and the silicon substrate 10, leading to poor anti-reflection effect of the first silicon nitride layer 41. It will also fail to effectively passivate the intrinsic amorphous silicon layer 20 and limit the practical application of the first silicon nitride layer 41. If the refractive index of the first silicon nitride layer 41 is greater than 2.4, it will result in a large difference in refractive index between sunlight and the silicon substrate 10, causing sunlight to be reflected instead of transmitted, and causing unnecessary dispersion effects, resulting in different wavelengths of light exhibiting different colors when passing through the first silicon nitride layer 41. Different behaviors affect color reproduction and clarity. If the refractive index of the first silicon nitride layer 41 is within a reasonable range, the reflection loss of sunlight in the first silicon nitride layer 41 can be significantly reduced, thereby improving light absorption efficiency and thus increasing the energy conversion efficiency of the solar cell 100. Reducing the reflection loss of sunlight can increase the amount of sunlight transmitted, thereby improving the photoelectric conversion efficiency of the solar cell 100. It can also effectively passivate the intrinsic amorphous silicon layer 20, reduce dangling bonds and surface state density, thereby reducing the surface recombination rate of the intrinsic amorphous silicon layer 20, extending the effective lifetime of charge carriers, and thus improving the performance of the solar cell 100. For example, the refractive index of the first silicon nitride layer 41 is 2.3 or 2.4, and the specific value is selected according to the actual situation.

[0042] n2 satisfies the relationship: 2.0 < n2 ≤ 2.2. That is, the refractive index of the second silicon nitride layer 42 must be within a reasonable range. If the refractive index of the second silicon nitride layer 42 is less than 2.0, it will not effectively reduce the reflection loss between sunlight and the silicon substrate 10, resulting in poor anti-reflection effect of the second silicon nitride layer 42. It will also fail to effectively passivate the intrinsic amorphous silicon layer 20 and limit the practical application of the second silicon nitride layer 42. If the refractive index of the second silicon nitride layer 42 is greater than 2.2, it will lead to a large difference in refractive index between sunlight and the silicon substrate 10, causing sunlight to be reflected instead of transmitted, and causing unnecessary dispersion effects, resulting in different wavelengths of light exhibiting different colors when passing through the second silicon nitride layer 42. Different behaviors affect color reproduction and clarity. If the refractive index of the second silicon nitride layer 42 is within a reasonable range, the reflection loss of sunlight in the second silicon nitride layer 42 can be significantly reduced, thereby improving light absorption efficiency and thus increasing the energy conversion efficiency of the solar cell 100. Reducing the reflection loss of sunlight can increase the amount of sunlight transmitted, thereby improving the photoelectric conversion efficiency of the solar cell 100. It can also effectively passivate the intrinsic amorphous silicon layer 20, reduce dangling bonds and surface state density, thereby reducing the surface recombination rate of the intrinsic amorphous silicon layer 20, extending the effective lifetime of charge carriers, and thus improving the performance of the solar cell 100. For example, the refractive index of the second silicon nitride layer 42 is 2.1 or 2.2, and the specific value is selected according to the actual situation.

[0043] n3 satisfies the relationship: 1.8 < n3 ≤ 2.0. That is, the refractive index of the third silicon nitride layer 43 must be within a reasonable range. If the refractive index of the third silicon nitride layer 43 is less than 2.0, it will not effectively reduce the reflection loss between sunlight and the silicon substrate 10, resulting in poor anti-reflection effect of the third silicon nitride layer 43. It will also fail to effectively passivate the intrinsic amorphous silicon layer 20 and limit the practical application of the third silicon nitride layer 43. If the refractive index of the third silicon nitride layer 43 is greater than 2.2, it will lead to a large difference in refractive index between sunlight and the silicon substrate 10, causing sunlight to be reflected instead of transmitted, and causing unnecessary dispersion effects, resulting in different wavelengths of light exhibiting different colors when passing through the third silicon nitride layer 43. Different behaviors affect color reproduction and clarity. If the refractive index of the third silicon nitride layer 43 is within a reasonable range, the reflection loss of sunlight in the third silicon nitride layer 43 can be significantly reduced, thereby improving light absorption efficiency and thus increasing the energy conversion efficiency of the solar cell 100. Reducing the reflection loss of sunlight can increase the amount of sunlight transmitted, thereby improving the photoelectric conversion efficiency of the solar cell 100. It can also effectively passivate the intrinsic amorphous silicon layer 20, reduce dangling bonds and surface state density, thereby reducing the surface recombination rate of the intrinsic amorphous silicon layer 20, extending the effective lifetime of charge carriers, and thus improving the performance of the solar cell 100. For example, the refractive index of the third silicon nitride layer 43 can be 1.9 or 2.0, with the specific value selected according to the actual situation.

[0044] Optionally, the refractive index of the multiple antireflection layers 40 is n4, where n4 satisfies the relationship: 2.0 ≤ n4 ≤ 2.1. It is understood that the refractive index of the multiple antireflection layers 40 must be within a reasonable range. If the refractive index of the multiple antireflection layers 40 is less than 2.0, it will result in an inability to effectively reduce reflection loss between sunlight and the silicon substrate 10, leading to poor antireflection performance. It will also fail to effectively passivate the intrinsic amorphous silicon layer 20 and limit the practical application of the multiple antireflection layers 40. If the refractive index of the multiple antireflection layers 40 is greater than 2.1, it will result in a large difference in refractive index between sunlight and the silicon substrate 10, causing sunlight to be reflected rather than transmitted, and inducing unnecessary dispersion effects, causing different wavelengths of light to exhibit different colors when passing through the multiple antireflection layers 40. Different antireflection layers exhibit different behaviors, thus affecting color reproduction and clarity. If the refractive index of multiple antireflection layers 40 is within a reasonable range, the reflection loss of sunlight through the multiple antireflection layers 40 can be significantly reduced, thereby improving light absorption efficiency and thus enhancing the energy conversion efficiency of the solar cell 100. Reducing the reflection loss of sunlight can increase the amount of sunlight transmitted, thereby improving the photoelectric conversion efficiency of the solar cell 100. It can also effectively passivate the intrinsic amorphous silicon layer 20, reduce dangling bonds and surface state density, thereby reducing the surface recombination rate of the intrinsic amorphous silicon layer 20, extending the effective lifetime of charge carriers, and thus improving the performance of the solar cell 100. For example, the refractive index of the multiple antireflection layers 40 can be 2.0 or 2.1, with the specific value selected according to the actual situation.

[0045] Optionally, the thickness of the first silicon nitride layer 41 is d3, where d3 satisfies the relationship: 15nm ≤ d3 ≤ 30nm. That is, the thickness of the first silicon nitride layer 41 must be within a reasonable range. If the thickness of the first silicon nitride layer 41 is less than 15nm, it will not effectively reduce light reflection loss, resulting in poor anti-reflection performance. It will not provide sufficient coverage to passivate surface defects in the intrinsic amorphous silicon layer 20, thus failing to effectively reduce the recombination rate of the intrinsic amorphous silicon layer 20, and is also insufficient to prevent corrosion of the intrinsic amorphous silicon layer 20 by time and contaminants, thereby reducing the stability and reliability of the solar cell 100. If the thickness of the first silicon nitride layer 41 is greater than 30nm... This would reduce the effective amount of sunlight reaching the silicon substrate 10, increase the cost of the first silicon nitride layer 41, and shorten the production cycle of the solar cell 100. It would also lead to an unnecessary increase in series resistance, thereby reducing the photoelectric conversion efficiency of the solar cell 100. If the thickness of the first silicon nitride layer 41 is within a reasonable range, it can reduce reflection losses, thereby improving the light absorption efficiency of the solar cell 100. It can also effectively cover and passivate defects on the surface of the intrinsic amorphous silicon layer 20, thereby reducing the carrier recombination rate and ultimately improving the energy conversion efficiency of the solar cell 100. For example, the thickness of the first silicon nitride layer 41 can be 15 nm, 20 nm, or 30 nm, with the specific value chosen based on the actual situation.

[0046] The thickness of the second silicon nitride layer 42 is d4, which satisfies the relationship: 20nm ≤ d4 ≤ 30nm. That is, the thickness of the second silicon nitride layer 42 must be within a reasonable range. If the thickness of the second silicon nitride layer 42 is less than 20nm, it will not effectively reduce light reflection loss, resulting in poor anti-reflection performance. It will not provide sufficient coverage to passivate surface defects in the intrinsic amorphous silicon layer 20, thus failing to effectively reduce the recombination rate of the intrinsic amorphous silicon layer 20, and is also insufficient to prevent corrosion of the intrinsic amorphous silicon layer 20 by time and contaminants, thereby reducing the stability and reliability of the solar cell 100. If the thickness of the second silicon nitride layer 42 is greater than 30nm... This would reduce the effective amount of sunlight reaching the silicon substrate 10, increase the cost of the second silicon nitride layer 42, and shorten the production cycle of the solar cell 100. It would also lead to an unnecessary increase in series resistance, thereby reducing the photoelectric conversion efficiency of the solar cell 100. If the thickness of the second silicon nitride layer 42 is within a reasonable range, it can reduce reflection losses, thereby improving the light absorption efficiency of the solar cell 100. It can also effectively cover and passivate defects on the surface of the intrinsic amorphous silicon layer 20, thereby reducing the carrier recombination rate and ultimately improving the energy conversion efficiency of the solar cell 100. For example, the thickness of the second silicon nitride layer 42 can be 20 nm, 25 nm, or 30 nm, with the specific value chosen based on the actual situation.

[0047] The thickness of the third silicon nitride layer 43 is d5, where d5 satisfies the relationship: 10nm ≤ d5 ≤ 20nm. This means the thickness of the third silicon nitride layer 43 must be within a reasonable range. If the thickness of the third silicon nitride layer 43 is less than 10nm, it will not effectively reduce light reflection loss, resulting in poor anti-reflection performance. It will not provide sufficient coverage to passivate surface defects in the intrinsic amorphous silicon layer 20, thus failing to effectively reduce the recombination rate of the intrinsic amorphous silicon layer 20, and is also insufficient to prevent corrosion of the intrinsic amorphous silicon layer 20 by time and contaminants, thereby reducing the stability and reliability of the solar cell 100. If the thickness of the third silicon nitride layer 43 is greater than 20nm... This would reduce the effective amount of sunlight reaching the silicon substrate 10, increase the cost of the third silicon nitride layer 43, and shorten the production cycle of the solar cell 100. It would also lead to an unnecessary increase in series resistance, thereby reducing the photoelectric conversion efficiency of the solar cell 100. If the thickness of the third silicon nitride layer 43 is within a reasonable range, it can reduce reflection losses, thereby improving the light absorption efficiency of the solar cell 100. It can also effectively cover and passivate defects on the surface of the intrinsic amorphous silicon layer 20, thereby reducing the carrier recombination rate and ultimately improving the energy conversion efficiency of the solar cell 100. For example, the thickness of the third silicon nitride layer 43 can be 10 nm, 15 nm, or 20 nm, with the specific value chosen based on the actual situation.

[0048] Optionally, the total thickness of the multiple antireflection layers 40 is d6, where d6 satisfies the relationship: 75nm ≤ d6 ≤ 85nm. It is understood that the thickness of the multiple antireflection layers 40 must be within a reasonable range. If the thickness of the multiple antireflection layers 40 is less than 75nm, this will result in the multiple antireflection layers 40 being unable to effectively reduce light reflection loss, leading to poor antireflection performance. This will not provide sufficient coverage to passivate surface defects in the intrinsic amorphous silicon layer 20, thus failing to effectively reduce the recombination rate of the intrinsic amorphous silicon layer 20, and is also insufficient to prevent erosion of the intrinsic amorphous silicon layer 20 by time and contaminants, thereby reducing the stability and reliability of the solar cell 100. If the thickness of the multiple antireflection layers 40 is greater than 85nm... This would reduce the effective amount of sunlight reaching the silicon substrate 10, increase the cost of multiple antireflection layers 40, and shorten the production cycle of the solar cell 100. It would also lead to an unnecessary increase in series resistance, thereby reducing the photoelectric conversion efficiency of the solar cell 100. If the thickness of the multiple antireflection layers 40 is within a reasonable range, the reflection loss of the multiple antireflection layers 40 can be reduced, thereby improving the light absorption efficiency of the solar cell 100. It can also effectively cover and passivate defects on the surface of the intrinsic amorphous silicon layer 20, thereby reducing the recombination rate of charge carriers and ultimately improving the energy conversion efficiency of the solar cell 100. For example, the thickness of the multiple antireflection layers 40 can be 75 nm, 80 nm, or 85 nm, with the specific value chosen based on the actual situation.

[0049] Specifically, the process flow is as follows:

[0050] The first step is to prepare an n-type monocrystalline silicon as a silicon substrate 10, and then clean, polish and texturize both sides of the monocrystalline silicon so that a textured surface 11 can be formed on both the front and back sides of the monocrystalline silicon.

[0051] The second step involves PECVD (Plasma Enhanced Chemical Vapor Deposition) coating of single-crystal silicon. The front surface is coated with an intrinsic silicon oxide layer 30 (SiOx) and an intrinsic amorphous silicon layer 20 (i), while the back surface is coated with an intrinsic amorphous silicon layer 20 (i) and a boron-doped microcrystalline silicon layer 50, forming a P+ layer. Specifically, nitrous oxide (N2O) and silane (SiH4) are introduced into the front surface to prepare the intrinsic silicon oxide layer 30. The SiH4:N2O ratio is 1-2:1, the pressure is 0.2-0.5 Torr, the thickness is 0.5-2 nm, and the coating power is 100-300 W. This corresponds to a nitrous oxide flow rate of 300-500 sccm and a silane flow rate of 500-1000 sccm, at a temperature of 150-200 °C. Intrinsic amorphous silicon layers 20 were prepared using hydrogen (H2) and silane (SiH4), with an H2:SiH4 ratio of 1-3:1, a pressure of 0.4-0.6 Torr, a thickness of 3-5 nm, and a deposition power of 200-400 W. This corresponds to a hydrogen flow rate of 500-3000 sccm and a silane flow rate of 500-1000 sccm, at a temperature of 180-210 °C. The back surface was then vented with hydrogen (H2) and silane (SiH4) to prepare the intrinsic amorphous silicon layer 20. Amorphous silicon layer 20 was prepared with H2:SiH4 = 1-2.5:1, pressure of 0.4-0.6 Torr, thickness of 6-8 nm, and deposition power of 200-500 W, corresponding to a hydrogen flow rate of 800-3000 sccm, a silane flow rate of 500-1000 sccm, and a temperature of 180-210℃. Boron-doped microstructures were prepared by introducing hydrogen (H2), silane (SiH4), carbon dioxide (CO2), and borane through the back side. The crystalline silicon layer is 50, H2:SiH4 = 250-380:1, pressure is 3-5 Torr, thickness is 22-27nm, coating power is 4000-7000W, that is, the flow rate of hydrogen is 10000-24000sccm, the flow rate of silane is 40-80sccm, the flow rate of carbon dioxide is 10-50sccm, the flow rate of borane is 20-100sccm, and the temperature is 140-170℃.

[0052] The third step involves PECVD deposition of an antireflection layer 40, i.e., a silicon nitride layer, on the front surface, followed by mask deposition on the back surface. Silicon nitride, silicon oxynitride, or silicon oxide masks can be selected. The antireflection layer 40 is deposited at a low temperature via PECVD on the front surface, with a decreasing refractive index gradient. Initially, ammonia (NH3) is introduced at 5000-7000 sccm, silane at 4000-5000 sccm, the power supply is 3000-4000W, and the pressure is 1-1.5 Torr. The process time is 100-200s, during which the first layer of silicon nitride, with a thickness of 15-30nm and a refractive index of 2.2-2.4, is deposited. Then, ammonia (NH3) gas is introduced at 6000-7000 sccm, silane at 3000-3500 sccm, the power supply is 4000-6000W, the pressure is 1-1.5 Torr, and the process time is 150-300s. During this time, the second layer of silicon nitride, with a thickness of 20-30nm and a refractive index of 2, is deposited. 0-2.2; Finally, ammonia (NH3) is introduced at 8000-10000 sccm, silane at 3000-4000 sccm, power supply at 3000-5000W, pressure at 1-1.5 Torr, and process time at 200-300s. At this point, the third layer of silicon nitride is deposited, with a thickness of 10-20nm and a refractive index of 1.85-2.2. The overall process temperature is controlled at 150-220℃, and the refractive index gradient of the three silicon nitride layers decreases progressively. The total thickness of the three-layer silicon nitride is controlled at 75-85nm, and the refractive index is controlled at 2.0-2.1. PECVD silicon nitride mask deposition is performed on the back surface, with ammonia (NH3) gas introduced at 5000-8000 sccm, silane at 2000-4000 sccm, temperature at 150-220℃, power supply at 2000-4000W, pressure at 1-1.5 Torr, process time at 600-800s, and mask thickness at 80-120nm.

[0053] The fourth step is laser patterning and cleaning of the back surface. Ultraviolet laser is used, and the laser pulse is less than 10 ns. First, laser etching is performed on the boron-doped microcrystalline silicon layer 50 on the back surface to damage the silicon nitride mask layer. Then, hydrofluoric acid (HF) cleaning is used to remove the laser-damaged area, the intrinsic amorphous silicon layer 20 and the boron-doped microcrystalline silicon layer 50. The boron-doped microcrystalline silicon layer 50 that was not treated by the laser is protected by the silicon nitride mask.

[0054] Step 5: PECVD deposition of an intrinsic amorphous silicon layer 20 and a phosphorus-doped microcrystalline silicon layer 60 on the back surface, forming an N+ layer. The intrinsic amorphous silicon layer 20 is prepared by introducing hydrogen and silane into the back surface, with an H2:SiH4 ratio of 1-2:1, a pressure of 0.4-0.6 Torr, a thickness of 5-8 nm, and a deposition power of 200-400 W (i.e., a hydrogen flow rate of 1000-2000 sccm, a silane flow rate of 500-1000 sccm, and a temperature of 180-200℃). The phosphorus-doped microcrystalline silicon layer 60 is prepared by introducing hydrogen, silane, carbon dioxide, and phosphine into the back surface. The parameters are: H2:SiH4 = 200-250:1, pressure 4-6 Torr, coating power 3000-5000W, hydrogen flow rate 10000-18000 sccm, silane flow rate 50-100 sccm, carbon dioxide flow rate 30-70 sccm, phosphine flow rate 300-500 sccm, thickness controlled at 20-25 nm, and temperature 1,70-190℃.

[0055] Step 6: Laser etching and cleaning of the back surface. Ultraviolet laser is used with a laser pulse of less than 10 ns. The intrinsic amorphous silicon layer 20 and phosphorus-doped microcrystalline silicon layer 60 on the boron-doped microcrystalline silicon layer 50 are treated by laser. Then, hydrofluoric acid cleaning is used to remove the mask layer on the phosphorus-doped microcrystalline silicon layer 60 and the residual intrinsic amorphous silicon and boron-doped microcrystalline silicon from the laser etching.

[0056] Step 7: The back surface is fully deposited with a TCO layer (Transparent Conductive Oxides 70) by APCVD (Atmospheric Pressure Chemical Vapor Deposition) magnetron sputtering.

[0057] Step 8: Laser isolation. An ultraviolet laser is used with a laser pulse of less than 10 ns. A groove is made in the region between the phosphorus-doped microcrystalline silicon layer 60 and the boron-doped microcrystalline silicon layer 50 on the back surface, thereby isolating the phosphorus-doped microcrystalline silicon layer 60 and the boron-doped microcrystalline silicon layer 50.

[0058] The ninth step involves screen printing silver positive electrode 80 and silver negative electrode 90, finally completing metallization and forming electrode contacts.

[0059] Specifically, ultraviolet radiation 60 kWh / m 2 Attenuation test:

[0060] Test method: The front and back sides of solar cells from different groups (number 100) were encapsulated using the same glass and encapsulating film. The front side was then irradiated, and the ultraviolet radiation was tested at 60 kWh / m². 2 The power attenuation before and after.

[0061] Comparative example: Conventional back-contact heterojunction solar cell, with a silicon nitride layer (refractive index 1.9) and an intrinsic amorphous silicon layer 20 (thickness 6-8nm) on the front surface forming passivation and antireflection.

[0062] Example 1: The front surface is made of silicon nitride layer with a gradient decreasing refractive index (2.2, 2.0 and 1.9 respectively), with a total refractive index of 2.0 and a thickness of 80nm.

[0063] Example 2: On the positive surface, based on Example 1, an intrinsic silicon oxide layer 30 is inserted between the silicon nitride layer and the silicon substrate 10. The thickness of the intrinsic silicon oxide layer 30 is 1 nm.

[0064] Example 3: On the positive surface, based on Example 2, the intrinsic amorphous silicon layer 20 is thinned to a thickness of 3 nm.

[0065] The experimental results are as follows:

[0066]

[0067] Conclusions: 1. The refractive index of the antireflection layer 40 decreases sequentially away from the intrinsic amorphous silicon layer 20, with the first silicon nitride layer 41 having the highest refractive index and the third silicon nitride layer 43 having the lowest. Increasing the refractive index of the antireflection layer 40 can reduce the impact of low-wavelength ultraviolet light transmission through the antireflection layer 40 on the irradiance reaching the silicon substrate 10. 2. The intrinsic amorphous silicon layer 20 contains a large number of Si-H bonds, which break under ultraviolet light irradiation, allowing hydrogen atoms to diffuse to the surface of the silicon substrate 10 and increasing the surface area of ​​the silicon substrate 10. The number of dangling bonds increases carrier recombination. The intrinsic silicon oxide layer 30, inserted between the intrinsic amorphous silicon layer 20 and the silicon substrate 10, can block hydrogen atom diffusion, thus reducing the passivation performance of the intrinsic amorphous silicon layer after ultraviolet irradiation. A thicker intrinsic amorphous silicon layer 20 increases ultraviolet attenuation. The better passivation performance of the intrinsic silicon oxide layer 30 can replace part of the passivation of the intrinsic amorphous silicon layer 20, thereby reducing the thickness of the intrinsic amorphous silicon layer 20 and further reducing ultraviolet attenuation. Analysis of the above experimental results shows that Example 3 improved ultraviolet attenuation by 0.8% compared to the comparative example, significantly reducing ultraviolet attenuation.

[0068] The photovoltaic module according to this utility model includes: the solar cell of the above embodiment. An intrinsic silicon oxide layer 30 is disposed between the silicon substrate 10 and the intrinsic amorphous silicon layer 20. The intrinsic amorphous silicon layer 20 contains a large number of Si-H bonds. After ultraviolet irradiation, the Si-H bonds break, and hydrogen atoms diffuse to the silicon substrate 10. The intrinsic silicon oxide can prevent hydrogen atoms from diffusing to the silicon substrate 10, thus avoiding the accumulation of hydrogen atoms on the surface of the silicon substrate 10, which would lead to passivation degradation. This reduces the risk of ultraviolet degradation. Furthermore, the intrinsic silicon oxide layer 30 can replace part of the passivation of the intrinsic amorphous silicon layer 20, thereby reducing the thickness of the amorphous silicon layer. This avoids the problem of parasitic absorption caused by an excessively thick amorphous silicon layer, which could lead to current short circuits and increased risk of ultraviolet degradation, thereby improving the reliability of the solar cell 100.

[0069] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0070] In the description of this utility model, "first feature" and "second feature" may include one or more of the features. In the description of this utility model, "multiple" means two or more. In the description of this utility model, "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. In the description of this utility model, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0072] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A solar cell (100) characterized by, include: Silicon substrate (10); An intrinsic amorphous silicon layer (20) is disposed on one side of a silicon substrate (10); An intrinsic silicon oxide layer (30) is disposed between the intrinsic amorphous silicon layer (20) and the silicon substrate (10).

2. The solar cell (100) according to claim 1, characterized in that The thickness of the intrinsic amorphous silicon layer (20) is d1, and d1 satisfies the relationship: 3nm≤d1≤5nm; The thickness of the intrinsic silicon oxide layer (30) is d2, and d2 satisfies the relationship: 0.5nm≤d2≤2nm.

3. The solar cell (100) according to claim 1, characterized in that Also includes: Multiple antireflection layers (40) are disposed on the side of the intrinsic amorphous silicon layer (20) away from the intrinsic silicon oxide layer (30) and stacked in a direction away from the intrinsic silicon oxide layer (30), and at least two of the antireflection layers (40) have different refractive indices.

4. Solar cell (100) according to claim 3, characterized in that The refractive index of the plurality of antireflection layers (40) decreases in the direction away from the intrinsic silicon oxide layer (30).

5. Solar cell (100) according to claim 4, characterized in that The plurality of said antireflective layers (40) include: A first silicon nitride layer (41) is disposed on the side of the intrinsic amorphous silicon layer (20) away from the intrinsic silicon oxide. A second silicon nitride layer (42) is disposed on the side of the first silicon nitride layer (41) away from the intrinsic amorphous silicon layer (20); A third silicon nitride layer (43) is disposed on the side of the second silicon nitride layer (42) away from the first silicon nitride layer (41).

6. Solar cell (100) according to claim 5, characterized in that The first silicon nitride layer (41) has a refractive index of n1, the second silicon nitride layer (42) has a refractive index of n2, and the third silicon nitride layer (43) has a refractive index of n3. n1, n2 and n3 satisfy the relationship: n1 > n2 > n3.

7. The solar cell (100) according to claim 6, characterized in that, n1 satisfies the relation: 2.2 < n1 ≤ 2.4; n² satisfies the relation: 2.0 < n² ≤ 2.2; n3 satisfies the relation: 1.8 < n3 ≤ 2.

0.

8. The solar cell (100) according to claim 5, characterized in that The thickness of the first silicon nitride layer (41) is d3, and d3 satisfies the relationship: 15nm≤d3≤30nm; and / or The thickness of the second silicon nitride layer (42) is d4, which satisfies the relationship: 20nm ≤ d4 ≤ 30nm; and / or The thickness of the third silicon nitride layer (43) is d5, and d5 satisfies the relationship: 10nm≤d5≤20nm.

9. The solar cell (100) according to claim 5, characterized in that The refractive index of the plurality of antireflective layers (40) is n4, which satisfies the relationship: 2.0 ≤ n4 ≤ 2.1; and / or The total thickness of the multiple antireflection layers (40) is d6, and d6 satisfies the relationship: 75nm≤d6≤85nm.

10. A photovoltaic module, characterized by include: The solar cell (100) according to any one of claims 1-9.

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