Solar cell and preparation method of passivation structure thereof, photovoltaic module
By preparing low-hydrogen AlOx and medium-hydrogen AlOx layers through a layered annealing process, and combining them with SiO2 and high-hydrogen SiOxNy layers, the problem of balancing passivation and UV resistance in the passivation layer was solved, thereby improving the performance and efficiency of the solar cell.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG RONMA SOLAR CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-07-14
AI Technical Summary
Existing solar cell passivation layers struggle to balance passivation performance and UV resistance. Hydrogen management methods cannot precisely control the dynamic distribution and bonding state of hydrogen at different interfaces, resulting in insufficient UV performance.
A layered annealing process was used to prepare low-hydrogen AlOx and medium-hydrogen AlOx layers. A stable silicon-oxygen bond and aluminum-oxygen bond network was first formed in the low-hydrogen AlOx layer, and the medium-hydrogen AlOx layer was used to further repair and replenish hydrogen elements. Combined with the SiO2 layer and the high-hydrogen SiOxNy layer, the interface repair and bulk replenishment of hydrogen elements were achieved.
It improves the passivation performance and UV resistance of the passivation structure, enhances the UV resistance and efficiency of solar cells, reduces the unstable hydrogen content, and reduces UV degradation.
Smart Images
Figure CN122396090A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of solar cell technology, specifically relating to solar cells and their passivation structure preparation methods, and photovoltaic modules. Background Technology
[0002] Current approaches to improving the ultraviolet (UV) resistance of TOPCon solar cells focus on optimizing the materials and structure of the passivation layer. However, to improve UV resistance, it is necessary to reduce the amount of unstable hydrogen in the passivation layer. Yet, to achieve good chemical passivation, hydrogen is needed to passivate the dangling bonds at the silicon interface. Therefore, current passivation layers for solar cells struggle to balance passivation performance and UV resistance. Summary of the Invention
[0003] In view of this, the first aspect of this application provides a method for preparing a passivation structure for a solar cell, the method comprising: Provide substrate; A low-hydrogen AlOx layer is formed on the substrate to obtain the first semi-finished product; The first semi-finished product is subjected to a first annealing process; A medium-hydrogen AlOx layer is formed on the side of the low-hydrogen AlOx layer facing away from the substrate to obtain a second semi-finished product; The second semi-finished product is subjected to a second annealing process; wherein the first annealing temperature of the first annealing process is lower than the second annealing temperature of the second annealing process.
[0004] The step of forming the low-hydrogen AlOx layer includes: The low-hydrogen AlOx layer is formed using a first atomic layer deposition process, and the thickness of the low-hydrogen AlOx layer is 2 nm to 5 nm; wherein the first atomic layer deposition process satisfies at least one of the following conditions: The first deposition temperature is 250℃~300℃; The material of the first aluminum source includes trimethylaluminum; The materials of the first oxygen source include ozone and water, and the volume ratio of ozone to water in the first oxygen source is (4~9):1.
[0005] Wherein, the first annealing process satisfies at least one of the following conditions: The first annealing temperature is 300℃~400℃; The first annealing time is 5 to 10 minutes; The first annealing process is carried out in a protective atmosphere.
[0006] The step of forming the intermediate hydrogen AlOx layer includes: The intermediate-hydrogen AlOx layer is formed using a second atomic layer deposition process, and the thickness of the intermediate-hydrogen AlOx layer is 3 nm to 10 nm; wherein the second atomic layer deposition process satisfies at least one of the following conditions: The second deposition temperature is 250℃~300℃; The material of the second aluminum source includes trimethylaluminum; The materials of the second oxygen source include ozone and water, and the volume ratio of ozone to water in the second oxygen source is (1~4):1.
[0007] Wherein, the second annealing process satisfies at least one of the following conditions: The second annealing temperature is 400℃~500℃; The second annealing time is 10 min to 20 min; The second annealing process is carried out in a protective atmosphere.
[0008] Prior to the step of forming the low-hydrogen AlOx layer, the method further includes: A SiO2 layer is formed on the substrate to obtain a third semi-finished product; The third semi-finished product is subjected to a third annealing process; wherein the third annealing temperature of the third annealing process is lower than the first annealing temperature of the first annealing process. A low-hydrogen AlOx layer is formed on the side of the SiO2 layer opposite to the substrate.
[0009] The thickness of the SiO2 layer is 1 nm to 1.5 nm; the third annealing process satisfies at least one of the following conditions: The third annealing temperature is 200℃~300℃; The third annealing time is 10-20 minutes; The third annealing process is carried out in a protective atmosphere.
[0010] The process, following the second annealing step, further includes: A high-hydrogen SiOxNy layer is formed on the side of the medium-hydrogen AlOx layer facing away from the substrate, to obtain the fourth semi-finished product; The fourth semi-finished product is subjected to a fourth annealing process; wherein the fourth annealing temperature of the fourth annealing process is greater than the second annealing temperature of the second annealing process.
[0011] The second aspect of this application provides a solar cell, the solar cell including a substrate and a passivation structure disposed on the substrate, the passivation structure being prepared using the passivation structure preparation method for the solar cell provided in the first aspect of this application.
[0012] A third aspect of this application provides a photovoltaic module, which includes a solar cell as provided in the second aspect of this application.
[0013] The solar cell and its passivation structure preparation method and photovoltaic module provided in this application, by performing a first annealing process after forming a low-hydrogen AlOx layer and before the outer layer has a hydrogen-rich film, so that the annealing energy is concentrated to utilize the limited hydrogen in the AlOx layer itself and the oxygen near the silicon interface to form a stable silicon-oxygen bond and aluminum-oxygen bond network, maximize the repair of silicon interface defects, further densify the low-hydrogen AlOx layer, and cure the structure in advance to improve the UV resistance of the passivation structure.
[0014] Then, a medium-hydrogen AlOx layer is formed. The double-layered low-hydrogen AlOx layer and the medium-hydrogen AlOx layer work together to further improve the UV resistance of the passivation structure. Furthermore, by performing layered annealing on the low-hydrogen AlOx layer and the medium-hydrogen AlOx layer, the hydrogen element is first repaired at the interface and then replenished in bulk. This not only ensures the hydrogen passivation required for the silicon-based structure and improves the passivation performance of the passivation structure, but also reduces the unstable hydrogen content in the passivation layer, avoids the ineffective residue of hydrogen in the bulk film layer, and improves the UV resistance of the passivation structure.
[0015] Therefore, this application improves both the passivation performance and the UV resistance of the passivation structure by setting a low-hydrogen AlOx layer and a medium-hydrogen AlOx layer in combination, and by performing layered annealing on the low-hydrogen AlOx layer and the medium-hydrogen AlOx layer. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.
[0017] Fig. 1 This is a schematic diagram of the structure of a solar cell provided in one embodiment of this application.
[0018] Fig. 2 This is a schematic flowchart illustrating a method for preparing a passivation structure for a solar cell according to an embodiment of this application.
[0019] Fig. 3 A schematic diagram of the structure of a solar cell provided for another embodiment of this application.
[0020] Fig. 4 This is a schematic flowchart of a method for preparing a passivation structure for a solar cell according to another embodiment of this application.
[0021] Fig. 5 This is a schematic diagram of the structure of a solar cell provided in another embodiment of this application.
[0022] Fig. 6 This is a schematic flowchart of a method for preparing a passivation structure for a solar cell, as provided in another embodiment of this application.
[0023] Labeling explanation: Solar cell 1, substrate 10, low-hydrogen AlOx layer 20, medium-hydrogen AlOx layer 30, SiO2 layer 40, high-hydrogen SiOxNy layer 50. Detailed Implementation
[0024] The following are preferred embodiments of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.
[0025] Before introducing the technical solution of this application, let's go over the technical issues in related technologies in detail.
[0026] Currently, the solutions for improving the UV resistance of the front side of TOPCon batteries focus on optimizing the materials and structure of the passivation layer.
[0027] For example, a stacked structure of ozone alumina layer and water alumina layer is used as a passivation layer, combined with high-temperature crystallization annealing and high-temperature silicon oxide capping layer. The idea is to reduce unstable silicon-hydrogen bonds by combining alumina stacks deposited with different precursors with high-temperature treatment.
[0028] For example, a silicon oxide layer, an aluminum oxide layer, and an aluminum nitride layer are sequentially prepared on a silicon substrate as a passivation layer. The idea behind this approach is to use the aluminum nitride layer as a barrier to block ultraviolet light and hydrogen escape.
[0029] However, the above methods all achieve hydrogen redistribution or structural stabilization after all film layers have been deposited, or only after a single overall annealing of the alumina layer. This hydrogen management approach cannot precisely control the dynamic distribution and bonding state of hydrogen at different interfaces, such as the Si / SiO2 interface and the SiO2 / Al2O3 interface. Hydrogen is either introduced too early and consumed by subsequent high-temperature processes, or its saturation at the interface becomes too high, thus becoming a source of instability under UV irradiation.
[0030] In view of this, in order to solve the above problems, please refer to the following: Figs. 1-2 This embodiment provides a method for preparing a passivation structure for a solar cell 1, the method comprising: S100 provides substrate 10.
[0031] The substrate 10 serves multiple functions, including light absorption, carrier generation, carrier transport, and mechanical support, supporting the entire battery's thin film layer and electrodes. Optionally, the substrate 10 is a silicon wafer. More preferably, the substrate 10 is an n-type silicon wafer.
[0032] S200, a low-hydrogen AlOx layer 20 is formed on the substrate 10 to obtain the first semi-finished product.
[0033] Further, step S200 of forming the low-hydrogen AlOx layer 20 includes: The low-hydrogen AlOx layer 20 is formed using a first atomic layer deposition process, and the thickness of the low-hydrogen AlOx layer 20 is 2 nm to 5 nm; wherein the first atomic layer deposition process satisfies at least one of the following conditions: The first deposition temperature is 250℃~300℃.
[0034] And / or, the material of the first aluminum source includes trimethylaluminum.
[0035] And / or, the material of the first oxygen source includes ozone and water, wherein the volume ratio of ozone to water in the first oxygen source is (4~9):1.
[0036] The low-hydrogen AlOx layer 20 is also known as the low-hydrogen aluminum hydroxide layer.
[0037] Specifically, the thickness of the low-hydrogen AlOx layer 20 can be exemplified by 2nm, 2.5nm, 3nm, 3.5nm, 4nm, 4.5nm, or 5nm, etc.
[0038] The first deposition temperature can be exemplified by 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, 295℃, or 300℃, etc.
[0039] In the first oxygen source, the volume ratio of ozone to water can be 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1, etc.
[0040] For example, using atomic layer deposition (ALD) at 250°C to 300°C, with trimethylaluminum (TMA) as the aluminum source and a mixture of ozone and water as the oxygen source, and an ozone to water volume ratio of (4 to 9): 1, a low-hydrogen AlOx layer 20 with a thickness of 2 nm to 5 nm is deposited on substrate 10. This mixed precursor process can obtain a dense low-hydrogen AlOx layer 20 with a moderately low but controllable hydrogen content.
[0041] S300, the first semi-finished product is subjected to a first annealing process.
[0042] Furthermore, the first annealing process satisfies at least one of the following conditions: The first annealing temperature is 300℃~400℃.
[0043] And / or, the first annealing time is 5 min to 10 min.
[0044] And / or, the first annealing process is performed in a protective atmosphere.
[0045] Specifically, the first annealing temperature can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, or 400℃, etc.
[0046] The first annealing time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes, etc.
[0047] Examples of protective atmospheres include nitrogen and argon.
[0048] For example, the first semi-finished product is annealed in a nitrogen atmosphere at 300℃~400℃ for 5min~10min.
[0049] This embodiment performs a first annealing process after the formation of the low-hydrogen AlOx layer 20, before the outer layer has a hydrogen-rich film. This allows the annealing energy to be concentrated on utilizing the limited hydrogen in the AlOx layer itself and the oxygen near the silicon interface to form a stable silicon-oxygen bond and aluminum-oxygen bond network, maximizing the repair of silicon interface defects and further densifying the low-hydrogen AlOx layer 20. This also allows for early curing of the structure and improved UV resistance of the passivation structure.
[0050] S400, a medium-hydrogen AlOx layer 30 is formed on the side of the low-hydrogen AlOx layer 20 facing away from the substrate 10, to obtain a second semi-finished product.
[0051] Further, step S400 of forming the intermediate hydrogen AlOx layer 30 includes: The intermediate-hydrogen AlOx layer 30 is formed using a second atomic layer deposition process, and the thickness of the intermediate-hydrogen AlOx layer 30 is 3 nm to 10 nm; wherein the second atomic layer deposition process satisfies at least one of the following conditions: The second deposition temperature is 250℃~300℃.
[0052] And / or, the material of the second aluminum source includes trimethylaluminum.
[0053] And / or, the material of the second oxygen source includes ozone and water, wherein the volume ratio of ozone to water in the second oxygen source is (1~4):1.
[0054] The intermediate hydrogen AlOx layer 30 is also called the intermediate aluminum hydroxide layer.
[0055] Specifically, the thickness of the intermediate hydrogen AlOx layer 30 can be exemplified by 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, or 10nm, etc.
[0056] The second deposition temperature can be exemplified by 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃, 295℃, or 300℃, etc.
[0057] In the first oxygen source, the volume ratio of ozone to water can be 1:1, 2:1, 3:1, or 4:1, etc.
[0058] For example, using atomic layer deposition (ALD) at 250°C to 300°C, with trimethylaluminum (TMA) as the aluminum source and a mixture of ozone and water as the oxygen source, and an ozone to water volume ratio of (1 to 4): 1, a medium-hydrogen AlOx layer 30 with a thickness of 3 nm to 10 nm is deposited on a low-hydrogen AlOx layer 20. The mixed precursor process can obtain a dense medium-hydrogen AlOx layer 30 with a moderately high but controllable hydrogen content.
[0059] S500, the second semi-finished product is subjected to a second annealing process; wherein, the first annealing temperature of the first annealing process is lower than the second annealing temperature of the second annealing process.
[0060] Furthermore, the second annealing process satisfies at least one of the following conditions: The second annealing temperature is 400℃~500℃.
[0061] And / or, the second annealing time is 10 min to 20 min.
[0062] And / or, the second annealing process is carried out in a protective atmosphere.
[0063] Specifically, the second annealing temperature can be exemplified by 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, or 500℃, etc.
[0064] The second annealing time can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min, etc.
[0065] Examples of protective atmospheres include nitrogen and argon.
[0066] For example, the second semi-finished product is annealed in a nitrogen atmosphere at 400℃~500℃ for 10min~20min.
[0067] In this embodiment, a medium-hydrogen AlOx layer 30 is formed on the low-hydrogen AlOx layer 20. The two layers of low-hydrogen AlOx layer 20 and medium-hydrogen AlOx layer 30 work together to further improve the UV resistance of the passivation structure. Furthermore, by performing layered annealing on the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30, the hydrogen element is first repaired at the interface and then replenished in bulk. This not only ensures the hydrogen passivation required by the silicon substrate and improves the passivation performance of the passivation structure, but also reduces the unstable hydrogen content in the passivation layer, avoids ineffective hydrogen residue in the bulk film layer, and improves the UV resistance of the passivation structure.
[0068] In summary, this embodiment improves both the passivation performance and the UV resistance of the passivation structure by combining a low-hydrogen AlOx layer 20 with a medium-hydrogen AlOx layer 30 and performing layered annealing on the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30.
[0069] Please refer to this as well. Figs. 3-4 In another embodiment, prior to step S200 of forming the low-hydrogen AlOx layer 20, the method further includes: S110, forming a SiO2 layer 40 on the substrate 10, to obtain the third semi-finished product.
[0070] Optionally, a SiO2 layer 40 is formed by thermal oxidation.
[0071] Optionally, the SiO2 layer 40 is disposed on the light-receiving surface of the substrate 10.
[0072] S120, the third semi-finished product is subjected to a third annealing process; wherein the third annealing temperature of the third annealing process is lower than the first annealing temperature of the first annealing process.
[0073] Furthermore, the thickness of the SiO2 layer 40 is 1 nm to 1.5 nm; the third annealing process satisfies at least one of the following conditions: The third annealing temperature is 200℃~300℃.
[0074] And / or, the third annealing time is 10 min to 20 min.
[0075] And / or, the third annealing process is carried out in a protective atmosphere.
[0076] The SiO2 layer 40 is also known as the silicon dioxide layer.
[0077] Specifically, the thickness of the SiO2 layer 40 can be 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, or 1.5 nm, etc.
[0078] The third annealing temperature can be exemplified by 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, or 300℃, etc.
[0079] The specific annealing time can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min, etc.
[0080] Examples of protective atmospheres include nitrogen and argon.
[0081] For example, the third semi-finished product is annealed at 200℃~300℃ for 10min~20min in a nitrogen or argon atmosphere.
[0082] S130, forming a low-hydrogen AlOx layer 20 on the side of the SiO2 layer 40 opposite to the substrate 10.
[0083] In solar cell 1, substrate 10, SiO2 layer 40, low-hydrogen AlOx layer 20, and medium-hydrogen AlOx layer 30 are stacked sequentially.
[0084] Therefore, in this embodiment, an ultrathin SiO2 layer 40 is formed on the light-receiving surface of the substrate 10 and subjected to low-temperature annealing to promote the reconstruction of the Si-SiO2 interface, reduce the initial interface state, achieve preliminary interface stability, and at a low temperature, prevent hydrogen from being introduced or dissipated prematurely. This provides a good foundation for the subsequent setting of the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30, which is beneficial to improving the passivation performance of the passivation structure and the UV resistance of the passivation structure.
[0085] Please refer to this as well. Figs. 5-6 In another embodiment, after step S500 of the second annealing process, the process further includes: S510, a high-hydrogen SiOxNy layer 50 is formed on the side of the medium-hydrogen AlOx layer 30 facing away from the substrate 10, to obtain the fourth semi-finished product.
[0086] The high-hydrogen SiOxNy layer 50 is also known as the high-hydrogen nitrogen oxide silicon layer.
[0087] Optionally, a high-hydrogen SiOxNy layer 50 is formed using a plasma-enhanced chemical vapor deposition process.
[0088] Optionally, the thickness of the high-hydrogen SiOxNy layer 50 is 70 nm to 110 nm.
[0089] The thickness of the high-hydrogen SiOxNy layer 50 can be specifically exemplified as 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm, 105nm, or 110nm, etc.
[0090] For example, a hydrogen-rich SiOxNy layer 50 with a thickness of 70 nm to 110 nm is deposited using plasma-enhanced chemical vapor deposition at 400 °C to 500 °C. By adjusting the ratio of silane, nitrous oxide (N2O), and ammonia (NH3), the hydrogen-rich SiOxNy layer 50 has a high hydrogen content and a suitable refractive index, serving as a bulk hydrogen source and antireflection layer for subsequent sintering processes.
[0091] S520, the fourth semi-finished product is subjected to a fourth annealing process; wherein the fourth annealing temperature of the fourth annealing process is greater than the second annealing temperature of the second annealing process.
[0092] Optionally, the fourth annealing temperature of the fourth annealing process is 700℃~900℃.
[0093] The fourth annealing temperature can be exemplified by 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, or 900℃, etc.
[0094] For example, the wire mesh sintering section of the fourth semi-finished product is subjected to high-temperature annealing at a temperature of 700℃~900℃.
[0095] In summary, the method for preparing the passivation structure of the solar cell 1 provided in this application includes the following steps in sequence: First, interface pretreatment and initial stabilization: an ultrathin SiO2 layer 40 is formed on the light-receiving surface of the silicon substrate, and the third annealing process is immediately performed to achieve initial interface stabilization. During this stage, the introduction of a large amount of hydrogen is deliberately avoided.
[0096] Then, an intrinsically stabilized alumina layer is deposited: a low-hydrogen AlOx layer 20 with a single precursor is deposited on the pretreated interface as the core field-effect passivation layer and UV-resistant host.
[0097] After depositing the aforementioned low-hydrogen AlOx layer 20 and before depositing any hydrogen-rich outer layer, a first annealing process is immediately performed. This is to maximize the repair of silicon interface defects, form a stable silicon-oxygen bond network, and stabilize the structure of the low-hydrogen AlOx layer 20, given that the hydrogen source is not yet abundant.
[0098] Subsequently, an alumina structure is stacked: an alumina bilayer film structure with a low-hydrogen AlOx layer 20 and a medium-hydrogen AlOx layer 30 is formed by stepwise atomic layer deposition, and then layered annealing is performed for a second annealing process.
[0099] The alumina double-layer film increases the overall alumina thickness, thus enhancing the UV blocking effect. Simultaneously, the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30 undergo layered annealing, ensuring the necessary hydrogen passivation for the silicon substrate while reducing the unstable hydrogen content in the film.
[0100] Next, a hydrogen source and protective layer is deposited: a high-hydrogen SiOxNy layer 50 is deposited on the annealed and stabilized medium-hydrogen AlOx layer 30. This layer serves as a "hydrogen reservoir" for subsequent processes such as medium-hydrogen diffusion, such as sintering, and provides anti-reflection and surface protection for solar cell 1, followed by the fourth annealing process.
[0101] This application also provides a solar cell 1, which includes a substrate 10 and a passivation structure disposed on the substrate 10. The passivation structure is prepared by the passivation structure preparation method of the solar cell 1 provided above in this application.
[0102] Optionally, the solar cell 1 is a TOPCon cell.
[0103] This application also provides a photovoltaic module, which includes the solar cell 1 provided above in this application.
[0104] The solar cell 1 and photovoltaic module provided in this application are prepared by using the passivation structure preparation method of the solar cell 1 provided above. In the preparation method of the passivation structure of the solar cell 1, after the formation of the low-hydrogen AlOx layer 20, before the outer layer has a hydrogen-rich film, a first annealing process is performed. In the absence of a large amount of hydrogen source, the energy of annealing is concentrated to utilize the limited hydrogen in the AlOx layer itself and the oxygen near the silicon interface to form a stable silicon-oxygen bond and aluminum-oxygen bond network, maximize the repair of silicon interface defects, further densify the low-hydrogen AlOx layer 20, and cure the structure in advance to improve the UV resistance of the passivation structure.
[0105] Then, a medium-hydrogen AlOx layer 30 is formed. The double-layered low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30 work together to further improve the UV resistance of the passivation structure. Furthermore, by performing layered annealing on the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30, the hydrogen element is first repaired at the interface and then replenished in bulk. This not only ensures the hydrogen passivation required by the silicon-based structure and improves the passivation performance of the passivation structure, but also reduces the unstable hydrogen content in the passivation layer, avoids the ineffective residue of hydrogen in the bulk film layer, and improves the UV resistance of the passivation structure.
[0106] Therefore, this application improves both the passivation performance and the UV resistance of the passivation structure by setting a low-hydrogen AlOx layer 20 and a medium-hydrogen AlOx layer 30 in combination, and by performing layered annealing on the low-hydrogen AlOx layer 20 and the medium-hydrogen AlOx layer 30.
[0107] To make the objectives and advantages of this application clearer, the effects of the passivation structure of the solar cell of this application will be further explained in detail below with reference to specific embodiment 1.
[0108] Example 1; A method for fabricating a passivation structure on the front side of a TOPCon solar cell, the specific steps of which are as follows: Step 1: An ultrathin SiO2 layer with a thickness of 1nm~1.5nm is grown on the front side of an n-type silicon wafer by thermal oxidation.
[0109] Step 2, Third Annealing Process, Interface Stabilization: Anneal at 200℃~300℃ for 10min~20min in a nitrogen or argon atmosphere. This step promotes the reconstruction of the Si-SiO2 interface, reduces the initial interface states, and the low temperature prevents premature introduction or escape of hydrogen.
[0110] Step 3: Using atomic layer deposition (ALD) technology, at 250°C~300°C, trimethylaluminum (TMA) is used as the aluminum source and a mixture of ozone and water is used as the oxygen source. The volume ratio of ozone to water is (4~9):1. A low-hydrogen AlOx layer with a thickness of 2nm~5nm is deposited on the substrate. This mixed precursor process can obtain a dense low-hydrogen AlOx layer with a moderately low but controllable hydrogen content.
[0111] Step 4, First Annealing Process: Anneal at 300℃~400℃ for 5min~10min in a nitrogen atmosphere. At this time, there is no hydrogen-rich film on the outer layer. The energy of annealing is concentrated on utilizing the limited hydrogen in the AlOx layer itself and the oxygen near the silicon interface to form a stable silicon-oxygen bond and aluminum-oxygen bond network, maximizing the repair of silicon interface defects, and curing the structure in advance to improve the UV resistance of the passivation structure.
[0112] Step 5: Using atomic layer deposition (ALD) at 250°C to 300°C, with trimethylaluminum (TMA) as the aluminum source and a mixture of ozone and water as the oxygen source, and an ozone to water volume ratio of (1 to 4): 1, a medium-hydrogen AlOx layer with a thickness of 3 nm to 10 nm is deposited on the low-hydrogen AlOx layer. The mixed precursor process can obtain a dense medium-hydrogen AlOx layer with a moderately high but controllable hydrogen content.
[0113] Step 6, Second annealing process: Anneal at 400℃~500℃ for 10min~20min in a nitrogen atmosphere.
[0114] Step 7: A hydrogen-rich SiOxNy layer with a thickness of 70 nm to 110 nm is deposited using plasma-enhanced chemical vapor deposition (PECVD) at 400 °C to 500 °C. By adjusting the ratio of silane, nitrous oxide (N2O), and ammonia (NH3), the hydrogen-rich SiOxNy layer is made to have a high hydrogen content and a suitable refractive index, serving as a bulk hydrogen source and antireflection layer for subsequent sintering processes.
[0115] Step 8, Fourth Annealing Process: High-temperature annealing is performed at the wire mesh sintering area to reduce the hydrogen content of the entire film layer. The annealing temperature is 700℃~900℃.
[0116] Benefits: Compared with conventional UV improvement schemes, the passivation structure preparation method of the solar cell proposed in this application not only improves the passivation performance of the passivation structure, but also improves the UV resistance performance of the passivation structure, resulting in a 0.05% higher solar cell efficiency and a 0.5% lower UV degradation.
[0117] In this application, by performing layered annealing on low-hydrogen AlOx layers and medium-hydrogen AlOx layers, hydrogen elements are first repaired at the interface and then replenished in bulk. This ensures that the most precious hydrogen atoms are preferentially used to passivate the most critical and difficult-to-repair silicon interface, fundamentally improving the intrinsic stability of the passivation structure and avoiding ineffective hydrogen residue in the bulk film layer.
[0118] Because the silicon interface is deeply passivated and stabilized in the early stages, the initial open-circuit voltage (Voc) of the battery is significantly improved. At the same time, the main low-hydrogen AlOx layer has become dense and stable through annealing before the formation of the hydrogen-rich environment, and the number of weak silicon-hydrogen bonds inside it is extremely small, thus exhibiting excellent resistance to UV-LID (Ultraviolet-Light Induced Degradation).
[0119] Furthermore, this application separates the three functions of "interface stabilization treatment", "intrinsic passivation layer formation" and "external hydrogen source supply and protection" on the time axis, and connects and couples them through a specific sequence of annealing processes, thereby realizing dynamic management of process timing and hydrogen elements.
[0120] Unless otherwise stated or in case of conflict, the terms or phrases used in this application shall have the following meanings: In this application, terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.
[0121] In this application, "one or more" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.
[0122] In this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0123] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part. They can refer to a mechanical connection or an electrical connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.
[0124] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form yet another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.
[0125] The above description represents some embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.
Claims
1. A method for preparing a passivation structure for a solar cell, characterized in that, The method for preparing the passivated structure includes: Provide substrate; A low-hydrogen AlOx layer is formed on the substrate to obtain the first semi-finished product; The first semi-finished product is subjected to a first annealing process; A medium-hydrogen AlOx layer is formed on the side of the low-hydrogen AlOx layer facing away from the substrate to obtain a second semi-finished product; The second semi-finished product is subjected to a second annealing process; wherein the first annealing temperature of the first annealing process is lower than the second annealing temperature of the second annealing process.
2. The method for preparing the passivation structure of a solar cell as described in claim 1, characterized in that, The steps for forming the low-hydrogen AlOx layer include: The low-hydrogen AlOx layer is formed using a first atomic layer deposition process, and the thickness of the low-hydrogen AlOx layer is 2 nm to 5 nm; wherein the first atomic layer deposition process satisfies at least one of the following conditions: The first deposition temperature is 250℃~300℃; The material of the first aluminum source includes trimethylaluminum; The materials of the first oxygen source include ozone and water, and the volume ratio of ozone to water in the first oxygen source is (4~9):
1.
3. The method for preparing the passivation structure of a solar cell as described in claim 2, characterized in that, The first annealing process satisfies at least one of the following conditions: The first annealing temperature is 300℃~400℃; The first annealing time is 5 to 10 minutes; The first annealing process is carried out in a protective atmosphere.
4. The method for preparing the passivation structure of a solar cell as described in claim 1, characterized in that, The step of forming the intermediate hydrogen AlOx layer includes: The intermediate-hydrogen AlOx layer is formed using a second atomic layer deposition process, and the thickness of the intermediate-hydrogen AlOx layer is 3 nm to 10 nm; wherein the second atomic layer deposition process satisfies at least one of the following conditions: The second deposition temperature is 250℃~300℃; The material of the second aluminum source includes trimethylaluminum; The materials of the second oxygen source include ozone and water, and the volume ratio of ozone to water in the second oxygen source is (1~4):
1.
5. The method for preparing the passivation structure of a solar cell as described in claim 4, characterized in that, The second annealing process satisfies at least one of the following conditions: The second annealing temperature is 400℃~500℃; The second annealing time is 10 min to 20 min; The second annealing process is carried out in a protective atmosphere.
6. The method for preparing the passivation structure of a solar cell as described in claim 1, characterized in that, Prior to the step of forming the low-hydrogen AlOx layer, the method further includes: A SiO2 layer is formed on the substrate to obtain a third semi-finished product; The third semi-finished product is subjected to a third annealing process; wherein the third annealing temperature of the third annealing process is lower than the first annealing temperature of the first annealing process. A low-hydrogen AlOx layer is formed on the side of the SiO2 layer opposite to the substrate.
7. The method for preparing the passivation structure of a solar cell as described in claim 6, characterized in that, The thickness of the SiO2 layer is 1 nm to 1.5 nm; the third annealing process satisfies at least one of the following conditions: The third annealing temperature is 200℃~300℃; The third annealing time is 10-20 minutes; The third annealing process is carried out in a protective atmosphere.
8. The method for preparing the passivation structure of a solar cell as described in claim 1, characterized in that, After the second annealing process, the method further includes: A high-hydrogen SiOxNy layer is formed on the side of the medium-hydrogen AlOx layer facing away from the substrate, to obtain the fourth semi-finished product; The fourth semi-finished product is subjected to a fourth annealing process; wherein the fourth annealing temperature of the fourth annealing process is greater than the second annealing temperature of the second annealing process.
9. A solar cell, characterized in that, The solar cell includes a substrate and a passivation structure disposed on the substrate, wherein the passivation structure is prepared by the passivation structure preparation method of the solar cell as described in any one of claims 1-8.
10. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell as described in claim 9.