Solar cell and method of manufacturing the same, stacked cell, and photovoltaic module

Abstract

The application relates to the technical field of solar cells, and provides a solar cell, a preparation method of the solar cell, a laminated cell and a photovoltaic module. The solar cell comprises a passivation layer and an anti-reflection layer which are arranged in layers, the passivation layer comprises an aluminum oxide matrix and diamond particles distributed in the aluminum oxide matrix, and the anti-reflection layer comprises silicon nitride. The solar cell provided by the application can solve the problem of film explosion in the metallization sintering process and improve the efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to solar cells and their fabrication methods, tandem cells and photovoltaic modules. Background Technology

[0002] Solar cells are devices that directly convert light energy into electrical energy through the photoelectric effect or photochemical effect. Due to their relatively stable photoelectric conversion efficiency, they have been widely used. In the traditional fabrication process of solar cells, metallization sintering is typically required to achieve ohmic contact between the electrode and the substrate, enhance electrode structural stability, optimize carrier collection efficiency, and ultimately ensure the photoelectric conversion performance and long-term reliability of the solar cell. However, current metallization sintering processes are prone to film bursting, leading to a decrease in solar cell efficiency. Summary of the Invention

[0003] Based on this, this application provides a solar cell and its preparation method, a tandem cell and a photovoltaic module, which can solve the problem of film bursting during the metallization sintering process and improve the efficiency of solar cells.

[0004] A first aspect of this application provides a solar cell including a passivation layer and an antireflection layer stacked together, the passivation layer comprising an alumina matrix and diamond particles distributed in the alumina matrix, and the antireflection layer comprising silicon nitride.

[0005] In some embodiments of this application, the surface of the diamond particles contains C=O bonds.

[0006] In some embodiments of this application, Al-OC covalent bonds exist between the diamond particles and the alumina matrix.

[0007] In some embodiments of this application, one or more of the following conditions are met:

[0008] (1) The average particle size of the diamond particles is 5 nm to 10 nm;

[0009] (2) The mass percentage of the diamond particles in the passivation layer is 1% to 5%.

[0010] In some embodiments of this application, the thickness of the passivation layer is 1 nm to 15 nm.

[0011] In some embodiments of this application, the antireflection layer includes a first sublayer, a second sublayer, and a third sublayer stacked sequentially along the thickness direction, and the first sublayer is in contact with the passivation layer;

[0012] The N / Si ratio of the first sublayer is (3~5):1, the N / Si ratio of the second sublayer is (6~8):1, and the N / Si ratio of the third sublayer is (10~12):1, wherein the N / Si ratio is the mass ratio of nitrogen to silicon.

[0013] In some embodiments of this application, the thickness of the first sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflection layer, the thickness of the second sub-layer is equivalent to 1 / 3 to 1 / 2 of the thickness of the antireflection layer, and the thickness of the third sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflection layer.

[0014] In some embodiments of this application, an emitter, a silicon substrate, a tunneling layer, a polysilicon layer, and an antireflection layer are sequentially stacked on the side of the passivation layer opposite to the antireflection layer.

[0015] The second aspect of this application provides a method for preparing a solar cell as described in the first aspect of this application, comprising:

[0016] The passivation layer was prepared using plasma-assisted atomic layer deposition.

[0017] The antireflection layer is prepared on one side surface of the passivation layer to obtain the solar cell.

[0018] In some embodiments of this application, the step of preparing the passivation layer using plasma-assisted atomic layer deposition includes:

[0019] The first aluminum source precursor is subjected to a first pulse treatment and then purged to form a precursor film.

[0020] After performing a second pulse treatment on the suspension containing the second aluminum source precursor and the diamond particles, the suspension is purged to form a mixed film on the precursor film.

[0021] The reactants were treated with a third pulse and then purged.

[0022] Repeat all the above steps 100 to 120 times to form the passivation layer.

[0023] In some embodiments of this application, one or more of the following conditions are met:

[0024] (1) The processing time of the first pulse is 0.1s to 0.2s;

[0025] (2) The processing time for the second pulse is 2s to 4s;

[0026] (3) The duration of the third pulse processing is 0.1s to 0.2s;

[0027] (4) The reactant includes H2O;

[0028] (5) The first aluminum source precursor and the second aluminum source precursor each independently include Al(CH3)3.

[0029] In some embodiments of this application, one or more of the following conditions are met:

[0030] (1) Before performing the first pulse treatment on the aluminum source precursor, the method further includes: performing oxygen plasma activation treatment on the diamond particles;

[0031] (2) After the second pulse processing, the process further includes: performing oxygen plasma activation treatment on the diamond particles.

[0032] A third aspect of this application provides a stacked solar cell, comprising a bottom cell and a top cell stacked together, wherein the bottom cell is a solar cell as described in the first aspect of this application or a solar cell prepared by the method described in the second aspect of this application.

[0033] A fourth aspect of this application provides a photovoltaic module, including at least one of the solar cell described in the first aspect of this application, a solar cell prepared by the method described in the second aspect of this application, and a tandem cell described in the third aspect of this application.

[0034] The passivation layer provided in this application contains diamond particles distributed in the alumina matrix. The incorporation of diamond particles helps to reduce the concentration of thermal stress during the metallization sintering process, reduce the cracking or peeling of the antireflection layer and / or passivation layer, reduce the generation of the explosion film, and improve the efficiency and reliability of the battery. At the same time, the incorporation of diamond particles has little impact on the passivation effect, so that the passivation layer can also have a good passivation effect. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a solar cell according to one embodiment of this application.

[0036] Figure reference numerals: 11 Antireflection layer; 12 Passivation layer; 13 Emitter; 14 Silicon substrate; 15 Tunneling layer; 16 Polycrystalline silicon layer; 17 Antireflection layer; 18 First electrode; 19 Second electrode. Detailed Implementation

[0037] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0038] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It should be noted that, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items, "above," "below," includes the stated number, and "one or more" with "multiple" means two or more.

[0040] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, and other numerical interval types.

[0041] In this document, for methods involving multiple steps, unless otherwise explicitly stated herein, there is no strict order constraint on the execution of these steps; they may be executed in any order other than those described. Moreover, any step may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed in turn, alternately, or simultaneously with other steps or parts of the sub-steps or stages of other steps.

[0042] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0043] Currently, passivation in some solar cells (such as TOPCon solar cells) primarily employs a SiNx / AlOx stacked structure. Typically, SiNx is deposited as the antireflection layer using plasma-enhanced chemical vapor deposition (PECVD), and AlOx is deposited as the passivation layer using atomic layer deposition (ALD). However, during the subsequent metallization sintering process, such solar cells are prone to cracking or peeling of the SiNx antireflection layer and / or AlOx passivation layer, resulting in film bursting and affecting cell efficiency and reliability.

[0044] Research has revealed that the main cause of the film bursting problem is the mismatch in thermal expansion coefficients between the SiNx antireflection layer and the AlOx passivation layer. This mismatch leads to thermal stress concentration during metallization sintering, resulting in film cracking or peeling and ultimately, film bursting. Simultaneously, the AlOx passivation layer itself experiences internal stress concentration during atomic layer deposition (typically ≥300℃), which further exacerbates film cracking or peeling during metallization sintering. In view of this, this application proposes the following technical solution.

[0045] Firstly, this application provides a solar cell, see [link to previous application]. Figure 1 It includes a passivation layer 12 and an antireflection layer 11 stacked together. The passivation layer 12 contains an alumina matrix and diamond particles distributed in the alumina matrix, and the antireflection layer 11 contains silicon nitride.

[0046] The passivation layer described in this application incorporates diamond particles within the alumina matrix. The inclusion of diamond particles, with their low coefficient of thermal expansion, helps reduce the mismatch in thermal expansion coefficients between the passivation layer and the antireflection layer, optimizing the thermomechanical matching of the interface. Furthermore, the diamond particles act as "stress anchors" to disperse stress, reducing localized stress. Simultaneously, the high thermal conductivity of the diamond particles helps reduce the concentration of thermal stress during the passivation layer's formation. Therefore, the inclusion of diamond particles in the passivation layer helps reduce thermal stress concentration during metallization sintering, decreasing cracking or peeling of the antireflection layer and / or the passivation layer, reducing the formation of a burst film, and improving battery efficiency and reliability. At the same time, the inclusion of diamond particles has a relatively small impact on the passivation effect, allowing the passivation layer to possess both good passivation performance and a high degree of passivation capability.

[0047] Furthermore, the incorporation of diamond particles helps to provide more nucleation sites for the deposition and growth of the passivation layer, thereby improving the adhesion of the passivation layer and enhancing the interfacial bonding strength.

[0048] In some embodiments, the alumina in the alumina matrix satisfies the chemical formula AlO. x1 1.5 ≤ x1 ≤ 2. In other embodiments, silicon nitride satisfies the chemical formula SiN. x2 , 1≤x2≤1.5.

[0049] In some embodiments, the surface of the diamond particles contains C=O bonds. This enhances the chemical bonding between the diamond particles and the alumina matrix, reduces diamond particle agglomeration, and allows for uniform distribution within the passivation layer, thereby optimizing the interfacial bonding between the passivation layer and the antireflection layer.

[0050] For example, the C=O bonds on the surface of diamond particles can be tested using X-ray photoelectron spectroscopy (XPS) or Fourier transform infrared spectroscopy (FTIR). During XPS testing, scanning the C 1s core electron spectrum and performing peak fitting reveals a clear, quantifiable peak near 287.8 eV, corresponding to the C=O bond. This peak's intensity is significantly higher than that of samples without C=O bonds (which are predominantly C / C peaks). During Fourier transform infrared spectroscopy testing, a peak at 1700 cm⁻¹... -1 ~1750 cm -1 This is a characteristic peak of the C=O bond stretching vibration, and the sample shows significant absorption at this point.

[0051] In some embodiments, Al-OC covalent bonds exist between the diamond particles and the alumina matrix. This facilitates stronger chemical bonding between the diamond particles and the alumina matrix, reduces diamond particle agglomeration, and allows for uniform distribution within the passivation layer, thereby optimizing the interfacial bonding between the passivation layer and the antireflection layer.

[0052] For example, the Al-OC covalent bond between diamond particles and the alumina matrix can be tested by X-ray photoelectron spectroscopy (XPS). During XPS testing, the presence of Al-OC covalent bonds can be determined by the following phenomena: (1) A new, independent peak may appear in the C 1s spectrum, or the CO peak (~286.3 eV) may undergo a slight shift and intensity change, in the range of 285.5 eV~286.5 eV, between C and C=O; (2) The main O 1s peak in pure alumina comes from the O-Al bond (~531.0 eV). If an Al-OC bond is formed, a shoulder peak or a new peak will appear on the higher binding energy side of the O 1s spectrum (~532.0 eV~532.5 eV), which belongs to the OC bond. (3) Because the chemical environment of Al has changed, the formation of an Al-OC bond may cause a slight chemical shift in the Al 2p peak (usually shifted to a lower binding energy direction by a few electron volts). Based on this, we can combine the above (1), (2), and (3) to make a comprehensive judgment on whether Al-OC covalent bonds exist.

[0053] In some embodiments, the average particle size of the diamond particles is 5nm to 10nm. For example, the average particle size of the diamond particles can be 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, or any value within the range above. Therefore, when diamond particles act as "stress anchors," they help to further reduce local stress, decrease stress concentration, and reduce the risk of film bursting. Simultaneously, the average particle size of the diamond particles is much smaller than the wavelength of light, resulting in less light transmittance loss. This reduces the risk of film bursting while allowing the passivation layer to have high light transmittance (e.g., transmittance > 95%) and a good passivation effect, thereby contributing to higher photoelectric conversion efficiency in the battery.

[0054] For example, the average particle size of diamond particles can be tested using the following method: Using a scanning electron microscope (e.g., ZEISS Sigma 300), refer to JY / T010-1996 to obtain a scanning electron microscope (SEM) image of the passivation layer. Specifically, the test can be performed as follows: Randomly select a test sample with a length × width = 50mm × 100mm on the passivation layer. Randomly select multiple test areas (e.g., 5 areas) within the test sample, and at a certain magnification (e.g., 1000x when measuring diamond particles), read the particle size of each diamond particle in each test area (i.e., take the distance between the two farthest points on the diamond particle as the particle size). Count the number and particle size values ​​of diamond particles in each test area, and take the arithmetic mean of the diamond particles in each test area. This is the number-average particle size of the diamond particles in the test sample. To ensure the accuracy of the test results, the above test can be repeated with multiple test samples (e.g., 10 samples), and the average value of each test sample can be taken as the final test result.

[0055] In some embodiments, the diamond particles constitute 1% to 5% of the passivation layer by mass, optionally 1% to 3%. For example, the mass percentage of diamond particles in the passivation layer can be 1%, 1.3%, 1.8%, 2.4%, 2.7%, 3%, 3.6%, 4%, 4.4%, 5%, or any range thereof. This reduces the occurrence of cracked films while also maintaining a good passivation effect.

[0056] In some embodiments, the thickness of the passivation layer is 1 nm to 15 nm. For example, the thickness of the passivation layer can be 1 nm, 4 nm, 8 nm, 13 nm, 15 nm, or within any range of these values. This facilitates a uniform distribution of diamond particles in the horizontal and vertical directions of the passivation layer, thereby optimizing the interfacial bonding between the passivation layer and the antireflection layer. For example, the thickness of the passivation layer can be measured using an ellipsometer.

[0057] In some embodiments, the antireflection layer 11 includes a first sublayer, a second sublayer, and a third sublayer stacked sequentially along the thickness direction, and the first sublayer is in contact with the passivation layer;

[0058] The N / Si ratio of the first sublayer is (3~5):1, the N / Si ratio of the second sublayer is (6~8):1, and the N / Si ratio of the third sublayer is (10~12):1, where the N / Si ratio is the mass ratio of nitrogen to silicon. This arrangement, combined with the structural design incorporating diamond particles in the passivation layer, facilitates a gradient transition of the thermal expansion coefficient from the antireflection layer to the passivation layer, thereby further reducing the occurrence of film bursting.

[0059] For example, the N / Si ratio of the first sublayer can be 3:1, 4:1, 5:1 or any of the above values; the N / Si ratio of the second sublayer can be 6:1, 7:1, 8:1 or any of the above values; and the N / Si ratio of the third sublayer can be 10:1, 11:1, 12:1 or any of the above values.

[0060] It is understood that the "N / Si ratio" mentioned in this application refers to the mass ratio of N to Si.

[0061] In some embodiments, the thickness of the first sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflective layer, the thickness of the second sub-layer is equivalent to 1 / 3 to 1 / 2 of the thickness of the antireflective layer, and the thickness of the third sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflective layer. This facilitates a better gradient transition of the thermal expansion coefficient from the antireflective layer to the passivation layer, thereby further reducing the occurrence of film bursting.

[0062] In some embodiments, the thickness of the antireflective layer is 75 nm to 85 nm. For example, the thickness of the antireflective layer can be 75 nm, 77 nm, 79 nm, 83 nm, 85 nm, or within any range of the above values.

[0063] In some implementations, see Figure 1 The solar cell also includes an emitter 13, a silicon substrate 14, a tunneling layer 15, a polycrystalline silicon layer 16, and an antireflection layer 17, which are sequentially stacked on the side of the passivation layer 12 opposite to the antireflection layer 11. In this case, the solar cell is a TOPCon solar cell. In this structure, the passivation layer can act as a stress buffer, which helps to reduce or even block the propagation of stress to the emitter.

[0064] It should also be noted that the passivation layer of this application is not limited to TOPCon solar cells. In addition to TOPCon solar cells, it can also be used in back contact (BC) cells, heterojunction (HJT) cells, perovskite cells and other solar cells.

[0065] In some embodiments, the silicon substrate 14 is an N-type silicon wafer doped with at least one of phosphorus, arsenic, and antimony. In other embodiments, the polycrystalline silicon layer 16 is an N-type polycrystalline silicon thin film doped with at least one of phosphorus, arsenic, and antimony, optionally phosphorus.

[0066] In some embodiments, the emitter is a P-type emitter, which is doped with boron.

[0067] In some embodiments, see Figure 1 The solar cell also includes a first electrode 18 disposed on the antireflection layer 11 and a second electrode 19 disposed on the antireflection layer 17. In other embodiments, the first electrode and the second electrode each independently include Ag.

[0068] In a second aspect, this application provides a method for fabricating a solar cell, which can be used to fabricate the solar cell of the first aspect of this application, and may include the following steps:

[0069] S1. The passivation layer is prepared by plasma-assisted atomic layer deposition.

[0070] S2. Prepare the antireflection layer on one side surface of the passivation layer to obtain the solar cell.

[0071] The method provided in this application, by employing plasma-assisted atomic layer deposition (PA-ALD) to prepare the passivation layer, helps to reduce or even avoid stress concentration and thermal damage to the passivation layer itself, thereby reducing the occurrence of film bursting.

[0072] In some embodiments, the step of preparing the passivation layer using plasma-assisted atomic layer deposition includes:

[0073] S11. After the first aluminum source precursor is subjected to the first pulse treatment, it is purged to form a precursor film.

[0074] S12. After the suspension of diamond particles and the second aluminum source precursor are subjected to a second pulse treatment, they are purged to form a mixed film on the precursor film.

[0075] S13. After the reactants are treated with a third pulse, they are purged.

[0076] Repeat all the above steps 100 to 120 times to form the passivation layer.

[0077] In the above steps, alternating pulse treatments in the order of steps S11, S12, and S13 can grow a diamond-doped alumina film, i.e., a passivation layer. Moreover, each cycle of steps S11 to S13 forms a diamond-doped alumina nanofilm, and after 100 to 120 cycles, the passivation layer is finally formed.

[0078] Furthermore, by controlling the processing time of the first pulse to be approximately equal, the processing time of the second pulse to be approximately equal, and the processing time of the third pulse to be approximately equal in each cycle, uniform doping of diamond particles in the passivation layer thickness direction can be achieved.

[0079] Furthermore, by adjusting the mass ratio of the second aluminum source precursor to the diamond particles in the suspension, the mass percentage of diamond particles in the passivation layer can be controlled; simultaneously, by adjusting the concentration of the suspension and / or the pulse time, the mass percentage of diamond particles in the passivation layer can also be controlled.

[0080] In some implementations, the duration of the first pulse processing is 0.1s to 0.2s. For example, the duration of the first pulse processing can be 0.1s, 0.2s, or within any of the above values.

[0081] In some embodiments, the duration of the second pulse processing is 2 to 4 seconds. For example, the duration of the second pulse processing can be 2 seconds, 3 seconds, 4 seconds, or any of the above values.

[0082] In some embodiments, the duration of the third pulse processing is 0.1s to 0.2s. For example, the duration of the first pulse processing can be 0.1s, 0.2s, or within any of the above values.

[0083] In some embodiments, the reactant includes H2O.

[0084] In some embodiments, the temperature at which the passivation layer is prepared using plasma-assisted atomic layer deposition is less than or equal to 200°C; further, the temperature is 180°C to 200°C. This helps to reduce or even avoid thermal damage, thereby reducing the occurrence of film bursting.

[0085] In some embodiments, the first aluminum source precursor and the second aluminum source precursor each independently comprise Al(CH3)3(TMA).

[0086] In some embodiments, prior to the first pulse treatment of the aluminum source precursor, the diamond particles may be subjected to oxygen plasma activation treatment. This allows for the control of the chemical state of the diamond surface, forming C=O bonds on the surface of the diamond particles and Al-OC covalent bonds between the diamond particles and the alumina matrix, which helps reduce diamond particle agglomeration and optimizes the subsequent interfacial bonding.

[0087] In some embodiments, after the second pulse treatment, the process may further include: performing oxygen plasma activation treatment on the diamond particles. This allows for the control of the chemical state of the diamond surface, forming C=O bonds on the surface of the diamond particles and Al-OC covalent bonds between the diamond particles and the alumina matrix, which helps reduce diamond particle agglomeration and optimizes the subsequent interfacial bonding.

[0088] In some embodiments, the step of preparing an antireflection layer on one side surface of the passivation layer may include: depositing silicon nitride using PECVD. Further, by controlling the volume ratio of the N source to the Si source and the deposition time, sublayers with different N / Si ratios and different thicknesses can be formed, thereby forming an antireflection layer in which a first sublayer, a second sublayer, and a third sublayer are sequentially stacked.

[0089] Thirdly, this application provides a tandem solar cell, comprising a bottom cell and a top cell stacked together. The bottom cell is a solar cell as described in the first aspect of this application or a solar cell prepared by the method described in the second aspect of this application. Further, the top cell comprises a perovskite solar cell.

[0090] It is understood that tandem solar cells include, but are not limited to, two-terminal tandem solar cells, three-terminal tandem solar cells, and four-terminal tandem solar cells. Furthermore, tandem solar cells include, but are not limited to, perovskite solar cells stacked with crystalline silicon solar cells.

[0091] Fourthly, this application provides a photovoltaic module, including at least one of the solar cell described in the first aspect of this application, a solar cell prepared by the method described in the second aspect of this application, and a tandem cell described in the third aspect of this application.

[0092] In some examples, the photovoltaic module includes: a battery string, which is formed by electrically connecting multiple solar cells or solar cells prepared by the above-described method, or by electrically connecting multiple tandem cells; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0093] It can be understood that solar cells or tandem cells are electrically connected in the form of a single sheet or multiple segments to form multiple cell strings, and multiple cell strings are electrically connected in series and / or parallel. Furthermore, solar cells or tandem cells can be single-sheet cells or sliced ​​cells; sliced ​​cells refer to cells formed from a single, complete cell through a cutting process.

[0094] The following are specific embodiments, which describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0095] Example 1

[0096] (1) Fabrication of TOPCon solar cells

[0097] (1.1) Using an N-type monocrystalline silicon wafer as the silicon substrate, the wafer is cleaned by RCA and then subjected to double-sided texturing to form a pyramid textured surface;

[0098] (1.2) A silicon substrate is placed in a reaction chamber for chemical vapor deposition to form a P-type emitter (1 μm thick) on the front side.

[0099] (1.3) Based on (1.2), perform back-side etching to remove the boron diffusion layer around the back side, and then polish.

[0100] (1.4) After etching, an oxide tunneling layer (1.5 nm thick) is deposited on the back side, and a polysilicon layer (150 nm thick) is deposited on the oxide tunneling layer; then phosphorus diffusion is performed on the polysilicon layer to form N + layer;

[0101] (1.5) Etch the front side to remove the polysilicon deposited around the front and edges, as well as the BSG layer on the front side;

[0102] (1.6) A passivation layer is deposited on the P-type emitter. The preparation process of the passivation layer is shown in step (2) below;

[0103] (1.7) An antireflection layer is deposited on the passivation layer and an antireflection layer is deposited on the N-type polysilicon layer. The preparation process of the antireflection layer is as shown in step (3) below. The preparation process of the antireflection layer is the same as step (3).

[0104] (1.8) Perform double-sided metallization, i.e., double-sided printed electrodes, and sinter (the peak temperature of the front sintering is 800℃, and the time is 1s~3s; the peak temperature of the back sintering is 750℃, and the time is 2s~5s) to form a TOPCon solar cell.

[0105] (2) Preparation of passivation layer

[0106] (2.1) Pretreatment of diamond particles

[0107] Nanodiamond particles (average particle size 8 nm) were subjected to oxygen plasma activation treatment (power 100 W, O2 flow rate 50 sccm) for 10 min.

[0108] (2.2) Pretreatment of suspension

[0109] The nanodiamond particles obtained in step (2.1) are mixed and dissolved in isopropanol to form a suspension (the concentration of the suspension is 1 wt%), and then the suspension is subjected to ALD treatment.

[0110] (2.3) Passivation layer prepared by plasma-assisted atomic layer deposition

[0111] ① Pulse the TMA for 0.1 s, then purge with N2 for 5 s;

[0112] ②Based on ①, the suspension and TMA were pulsed for 2 s, then oxygen plasma activation treatment (power of 50W, O2 flow rate of 50 sccm) was performed for 3 s, followed by N2 purging for 5 s;

[0113] ③ Based on ②, pulse H2O for 0.1 s, then purge with N2 for 5 s;

[0114] Repeat steps ① to ③ above 100 times to form a passivation layer (5 nm thick); in the passivation layer, the mass percentage of nanodiamond particles is 1%.

[0115] (3) Antireflection layer prepared by PECVD

[0116] ① Adjust the volume ratio of NH3 to SiH4 to 3:1, the deposition power to 300 W, and the deposition time to 110 s to form the first sublayer (thickness of 15 nm, N / Si ratio of 3:1).

[0117] ②Based on the first sublayer, the volume ratio of NH3 to SiH4 is adjusted to 6:1, the deposition power is 300 W, and the deposition time is 120 s to form the second sublayer (thickness is 16 nm, N / Si ratio is 6:1).

[0118] ③ Based on the second sublayer, the volume ratio of NH3 to SiH4 is adjusted to 10:1, the deposition power is 300 W, and the deposition time is 340 s to form the third sublayer (thickness is 47 nm, N / Si ratio is 10:1).

[0119] Example 2

[0120] Similar to the preparation method in Example 1, the main difference is that the oxygen plasma activation treatment in steps (2.1) and (2.3) is omitted.

[0121] Example 3

[0122] Similar to the preparation method in Example 1, the main difference is that in step (2.1), nanodiamond particles with an average particle size of 5 nm are used instead.

[0123] Example 4

[0124] Similar to the preparation method in Example 1, the main difference is that in step (2.1), nanodiamond particles with an average particle size of 10 nm are used instead.

[0125] Example 5

[0126] Similar to the preparation method in Example 1, the main difference is that in step (2.1), nanodiamond particles with an average particle size of 1 μm are used instead.

[0127] Example 6

[0128] Similar to the preparation method in Example 1, the main difference is that in step (2.2), the concentration of the suspension is adjusted to 1.5 wt%, so that the mass ratio of the nanodiamond particles in the passivation layer is 1.5%.

[0129] Example 7

[0130] Similar to the preparation method in Example 1, the main difference is that in step (2.2), the concentration of the suspension is adjusted to 5wt% so that the mass ratio of the nanodiamond particles in the passivation layer is 5%.

[0131] Example 8

[0132] Similar to the preparation method of Example 1, the main difference is that in step (3), steps ② and ③ are omitted, and the deposition time of step ① is adjusted to 570s to prepare a single-layer antireflection layer (N / Si ratio is 3:1, and the thickness is the same as that of the antireflection layer in Example 1).

[0133] Comparative Example 1

[0134] Similar to the preparation method in Example 1, the main difference is that step (2.1) is omitted, and in step (2.2), TMA of equal mass is used to replace the nanodiamond particles so that the passivation layer does not contain diamond particles.

[0135] The solar cells prepared in Examples 1-8 and Comparative Example 1 were subjected to relevant performance tests, and the test results are shown in Table 1 below.

[0136] The test conditions or standards for each performance test item are as follows:

[0137] (1) Film bursting rate test

[0138] Use online EL and PL statistical yield data to calculate the proportion of bursting wafers to the total number of wafers;

[0139] PL: BT Imaging, Germany, 790nm infrared laser;

[0140] EL: ISC Konstanz, Germany, EL-Scan.

[0141] (2) Adhesion test (scratch test)

[0142] Instrument model: Revestest RS8000;

[0143] Diamond indenter tip radius: 2 μm;

[0144] Initial load: 0.5 mN (to ensure stable initial contact);

[0145] Final load: 50 N (to ensure that the scratch contains the critical point of film failure);

[0146] Scratch length: 3mm;

[0147] Loading rate: 20 mN / min;

[0148] Scratching speed: 5 mm / min;

[0149] Sample size: 3 samples per group, 3 tests per sample, and average value.

[0150] (3) Minority birth lifetime test

[0151] Instrument model: Sinton WCT-120;

[0152] Sample thickness: 130 μm;

[0153] Resistivity: ~1 Ω·cm;

[0154] Surface texture: velvety;

[0155] Mode: QSS-PC.

[0156] (4) Photoelectric conversion efficiency

[0157] The fabricated TOPCon solar cells were characterized under standard testing conditions: using a Newport Oriel Sol3A Class AAA solar simulator, with AM 1.5G spectrum and 1000 W / m² light intensity, the IV characteristic curves of the cells were scanned using a Keithley 2450 source measurement unit. During the test, the cells were fixed on a temperature-controlled sample stage, with the temperature precisely maintained at 25°C, and the open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency data were obtained.

[0158] Table 1

[0159]

[0160] Table 1 shows that comparing Example 1 with Comparative Example 1 demonstrates that incorporating diamond particles, especially nanodiamond particles, in the passivation layer is beneficial for reducing the bursting rate and improving the photoelectric conversion efficiency of the battery. Comparing Examples 1 and 2 shows that the C=O bonds formed on the diamond surface through oxygen plasma activation treatment enhance adhesion and improve interfacial bonding. Comparing Examples 1 with Examples 3-5 shows that controlling the average particle size of the nanodiamond particles within a suitable range is beneficial for achieving higher photoelectric conversion efficiency in the battery. Comparing Examples 1 with Examples 6-7 shows that controlling the mass ratio of nanodiamond particles in the passivation layer within a suitable range is beneficial for further reducing the bursting rate while maintaining photoelectric conversion efficiency. Comparing Examples 1 and 8 shows that a gradient-set antireflective layer is beneficial for further reducing the bursting rate.

[0161] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0162] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A solar cell, characterized in that, It includes a passivation layer and an antireflection layer stacked together, wherein the passivation layer comprises an alumina matrix and diamond particles distributed in the alumina matrix, and the antireflection layer comprises silicon nitride.

2. The solar cell according to claim 1, characterized in that, The surface of the diamond particles contains C=O bonds.

3. The solar cell according to claim 2, characterized in that, There are Al-OC covalent bonds between the diamond particles and the alumina matrix.

4. The solar cell according to any one of claims 1 to 3, characterized in that, One or more of the following conditions must be met: (1) The average particle size of the diamond particles is 5 nm to 10 nm; (2) The mass percentage of the diamond particles in the passivation layer is 1% to 5%.

5. The solar cell according to any one of claims 1 to 3, characterized in that, The thickness of the passivation layer is 1 nm to 15 nm.

6. The solar cell according to any one of claims 1 to 3, characterized in that, The antireflection layer includes a first sub-layer, a second sub-layer, and a third sub-layer stacked sequentially along the thickness direction, and the first sub-layer is in contact with the passivation layer; The N / Si ratio of the first sublayer is (3~5):1, the N / Si ratio of the second sublayer is (6~8):1, and the N / Si ratio of the third sublayer is (10~12):1, wherein the N / Si ratio is the mass ratio of nitrogen to silicon.

7. The solar cell according to claim 6, characterized in that, The thickness of the first sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflective layer, the thickness of the second sub-layer is equivalent to 1 / 3 to 1 / 2 of the thickness of the antireflective layer, and the thickness of the third sub-layer is equivalent to 1 / 4 to 1 / 3 of the thickness of the antireflective layer.

8. The solar cell according to any one of claims 1 to 3, characterized in that, It also includes an emitter, a silicon substrate, a tunneling layer, a polysilicon layer, and an antireflection layer, which are sequentially stacked on the side of the passivation layer away from the antireflection layer.

9. A method for preparing a solar cell according to any one of claims 1 to 8, characterized in that, include: The passivation layer was prepared using plasma-assisted atomic layer deposition. The antireflection layer is prepared on one side surface of the passivation layer to obtain the solar cell.

10. The method for preparing a solar cell according to claim 9, characterized in that, The steps for preparing the passivation layer using plasma-assisted atomic layer deposition include: The first aluminum source precursor is subjected to a first pulse treatment and then purged to form a precursor film. After performing a second pulse treatment on the suspension containing the second aluminum source precursor and the diamond particles, the suspension is purged to form a mixed film on the precursor film. The reactants were treated with a third pulse and then purged. Repeat all the above steps 100 to 120 times to form the passivation layer.

11. The method for preparing a solar cell according to claim 10, characterized in that, One or more of the following conditions must be met: (1) The processing time of the first pulse is 0.1s to 0.2s; (2) The processing time for the second pulse is 2s to 4s; (3) The duration of the third pulse processing is 0.1s to 0.2s; (4) The reactant includes H2O; (5) The first aluminum source precursor and the second aluminum source precursor each independently include Al(CH3)3.

12. The method for preparing a solar cell according to claim 10, characterized in that, One or more of the following conditions must be met: (1) Before performing the first pulse treatment on the aluminum source precursor, the method further includes: performing oxygen plasma activation treatment on the diamond particles; (2) After the second pulse processing, the process further includes: performing oxygen plasma activation treatment on the diamond particles.

13. A stacked battery, characterized in that, It includes a bottom cell and a top cell stacked together, wherein the bottom cell is a solar cell according to any one of claims 1 to 8 or a solar cell prepared by the method of preparing a solar cell according to any one of claims 9 to 12.

14. A photovoltaic module, characterized in that, It includes at least one of the solar cells according to any one of claims 1 to 8, solar cells prepared by the method of preparing solar cells according to any one of claims 9 to 12, and tandem cells according to claim 13.

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