Solar cell metal electrode and preparation method and application thereof

Abstract

The invention belongs to the related technical field of solar cells, and discloses a solar cell metal electrode and a preparation method and application thereof. According to the preparation method of the solar cell metal electrode, a traditional metal electroplating method is improved, the step of laser modification of the seed layer is introduced, and through selective doping of metal atoms of the seed layer, regulation and control of a TCO energy band structure are achieved in a metal contact area, so that the overall performance of a solar cell is improved. Meanwhile, according to the preparation method of the solar cell metal electrode, mask layer stripping and seed layer selective etching in a traditional technology do not need to be carried out, the metal electroplating process is simplified, an existing solar cell preparation process can be better compatible, and a new thought is provided for large-scale application of the electroplating technology.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a solar cell metal electrode, its preparation method, and its application. Background Technology

[0002] Metal electroplating has become a major trend in the metallization of high-efficiency solar cells. It can reduce shading losses, increase electrode conductivity and fill factor (FF), and has great potential to reduce and improve cell efficiency. However, existing technologies generally use organic films for patterning, which requires the treatment of organic waste, and the patterning process, such as photolithography, is relatively complex and costly.

[0003] Therefore, in order to optimize the metal electroplating process and improve the efficiency of solar cells, it is urgent to develop a new method for preparing solar cell electrodes. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a solar cell metal electrode, its preparation method, and its application. The preparation method of the metal electrode does not require the mask layer stripping and seed layer selective etching in traditional processes, which not only simplifies the metal electroplating process but also helps to improve the overall performance of the solar cell.

[0005] To address the aforementioned technical problems, a first aspect of the present invention provides a method for preparing a metal electrode for a solar cell, comprising the following steps:

[0006] (1) A modified seed layer and a barrier layer are sequentially patterned and deposited on the surface of the solar cell precursor, and CCD alignment Mark points are reserved during the patterned deposition of the modified seed layer.

[0007] (2) Positioning and alignment are performed using the Mark points, and the area of ​​the modified seed layer is scanned with a laser to perform laser grooving and laser modification;

[0008] (3) Electroplating is used to deposit metal electrodes on the solar cell precursor modified in step (2) to obtain the solar cell metal electrode.

[0009] Specifically, this invention involves sequentially patterning and depositing a modified seed layer and a barrier layer on the surface (including the upper and / or lower surfaces) of a solar cell precursor. Then, using marker points pre-defined during the patterning deposition process for positioning, a laser is used to scan the area of ​​the modified seed layer, performing laser grooving and laser modification. Specifically, laser grooving refers to etching the scanned area of ​​the barrier layer film, while laser modification involves the laser acting on the modified seed layer to induce metal doping into the transparent conductive oxide (TCO) layer of the solar cell precursor. This alters the electrical properties of the TCO, making its work function and carrier concentration more suitable for the interfacial electrical contact with adjacent layers, thereby reducing carrier transport losses. Finally, metal electrode deposition is performed to obtain the solar cell metal electrode. Compared to traditional metal plating methods, this invention eliminates the need for mask layer stripping and selective etching of the seed layer, simplifying the metal plating process and making it more compatible with current solar cell fabrication processes. Meanwhile, by introducing laser to modify the TCO, the present invention enables selective doping of metal atoms in the seed layer, thereby achieving control over the band structure of the TCO in the metal contact region, which is more conducive to improving the overall performance of the solar cell.

[0010] The working principle of the solar cell metal electrode prepared by this invention is as follows: The carrier transport mechanisms at the TCO / Si interface mainly include direct tunneling (DT), thermal field emission (TE), tail-state defect-assisted tunneling (TAT-TS), surface dangling bond defect-assisted tunneling (TAT-DBS), and band-to-band tunneling (B2BT). When B2BT dominates, carrier transport at the doped-layer / transparent conductive oxide layer (doped-layer / TCO) interface is sufficient, which can enhance the tunneling current. Since the barrier width of silicon materials such as amorphous silicon (a-Si) and polycrystalline silicon (poly-Si) is limited, the enhancement of the tunneling current at the doped-layer / TCO interface cannot be achieved solely by relying on high doping concentration. Figure 1 The band structure diagram of a silicon heterojunction solar cell (SHJ cell) shows that the work function (Wf) matching of the two materials can be achieved by adjusting the work function difference ΦB between the TCO and the doped-layer to meet the basic conditions of B2BT. For example, on the hole transport layer side, the conduction band (CB) of the TCO must be below the valence band of the absorption layer. This invention modifies the band structure of the TCO by laser doping modification of the TCO under the metal electrode coverage area, improving the contact at the doped-layer / TCO interface and allowing more photocurrent to be collected by the metal electrode.

[0011] In some embodiments of the present invention, in step (1), the modified seed layer is formed by metal deposition, wherein the metal is selected from at least one of silver, aluminum, magnesium, vanadium, manganese, chromium, yttrium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, tin, indium, gallium, zinc, nickel, and titanium. Preferably, the metal is selected from at least one of aluminum, indium, zinc, gallium, tungsten, tin, magnesium, nickel, and titanium.

[0012] In some embodiments of the present invention, in step (1), the deposition method of the modified seed layer is selected from laser transfer or screen printing.

[0013] In some embodiments of the present invention, the laser transfer step includes: firstly, depositing a modified seed layer source film over the entire area on a flexible transparent substrate; then placing the flexible transparent substrate with the modified seed layer source film deposited on the upper and lower surfaces of the solar cell precursor, and irradiating it with a laser according to the path of the electrode pattern.

[0014] Specifically, during the laser transfer process, the metal source film of the modified seed layer absorbs most of the laser energy to form a molten state. The metal vapor pressure at the molten point increases sharply, pushing the molten liquid to deposit on the surface of the acceptor. After cooling and solidifying, it becomes a metal film that adheres to the surface of the solar cell precursor.

[0015] In some embodiments of the present invention, the flexible transparent substrate is selected from any one of polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, and transparent polyimide (PI) film.

[0016] In some embodiments of the present invention, in the laser transfer, the deposition method is selected from any one of sputtering, evaporation, and ion plating.

[0017] In some embodiments of the present invention, the vertical distance between the flexible transparent substrate on which the modified seed layer source film is deposited and the solar cell precursor is 0-100 μm.

[0018] In some embodiments of the present invention, the laser irradiation is performed on the side of the flexible transparent substrate where the modified seed layer source film is not deposited, and the laser irradiation parameters are: wavelength of 1064 nm, power of 0-500 W, focal plane spot radius of 5-100 μm, scanning speed of 1-10000 mm / s, repetition frequency of 1-100 kHz, and energy density of 0.2-3 J / cm². 2 .

[0019] In some embodiments of the present invention, in step (1), the thickness of the modified seed layer is 10 nm-3 μm.

[0020] In some embodiments of the present invention, in step (1), the linewidth of the modified seed layer is 5-100 μm.

[0021] In some embodiments of the present invention, in step (1), the barrier layer is formed by depositing at least one of oxides, nitrides, and oxynitrides.

[0022] In some embodiments of the present invention, in step (1), the barrier layer is deposited from at least one of silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride. Preferably, it is silicon oxide or silicon oxynitride.

[0023] Specifically, the barrier layer serves two purposes: firstly, it acts as a mask layer for the subsequent growth of copper metal electrodes, preventing leakage in non-electrode areas; secondly, it acts as a barrier layer for the battery, mitigating the effects of sodium ion (Na+) degradation during actual operation. + This reduces the intrusion of water vapor into the battery, increasing the reliability and stability of solar cell devices and modules.

[0024] In some embodiments of the present invention, the barrier layer is deposited by a method selected from plasma-enhanced chemical vapor deposition or atomic layer deposition.

[0025] In some embodiments of the present invention, the thickness of the barrier layer is 20-150 nm.

[0026] In some embodiments of the present invention, the band gap of the barrier layer is 3.5-9 eV.

[0027] In some embodiments of the present invention, the refractive index of the barrier layer is 1.4-2.

[0028] In some embodiments of the present invention, in step (1), the solar cell precursor includes a transparent conductive oxide layer, a hole or electron passivation contact layer, a doped crystalline silicon layer, a hole or electron passivation contact layer, a transparent conductive oxide layer, or a passivation antireflection layer stacked sequentially.

[0029] In some embodiments of the present invention, the transparent conductive oxide layer is selected from indium oxide, tin oxide, zinc oxide, titanium oxide, gallium oxide, or cadmium oxide doped with any one of aluminum, gallium, tin, tungsten, tantalum, or cerium. Preferably, it is at least one of aluminum-doped zinc oxide, gallium-doped zinc oxide, indium tin oxide, or tungsten-doped indium oxide.

[0030] In some embodiments of the present invention, the deposition method of the transparent conductive oxide layer is selected from any one of sputtering, ion plating, and reactive plasma deposition.

[0031] In some embodiments of the present invention, the thickness of the transparent conductive oxide layer is 10-200 nm.

[0032] In some embodiments of the present invention, the electron or hole passivation contact layer is selected from any one of silicon oxide thin film / doped polycrystalline silicon thin film, intrinsic hydrogenated amorphous silicon thin film / doped hydrogenated amorphous silicon thin film.

[0033] In some embodiments of the present invention, the deposition method of the electron or hole passivation contact layer is selected from any one of plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, and hot-filament chemical vapor deposition.

[0034] In some embodiments of the present invention, the passivation antireflection layer is formed by depositing at least one of silicon oxide, aluminum oxide, silicon nitride, and silicon oxynitride.

[0035] In some embodiments of the present invention, the passivation antireflection layer is deposited by a method selected from plasma-enhanced chemical vapor deposition or atomic layer deposition.

[0036] In some embodiments of the present invention, the doped crystalline silicon has a pyramid-shaped textured surface.

[0037] In some embodiments of the present invention, the pyramid-shaped textured surface is formed by chemical etching or ion etching.

[0038] In some embodiments of the present invention, the structure of the solar cell precursor is: TCO / a-Si:H(n) / a-Si:H(i) / c-Si(n) / a-Si:H(i) / a-Si:H(p) / TCO or TCO / poly-Si(p) / SiOx / c-Si(n) / SiOx / poly-Si(n) / SiOxNy.

[0039] In some embodiments of the present invention, in step (2), the parameters of the laser scanning are: wavelength of 355-1064nm, pulse width of 1ps-100μs, power of 25-500W, focal plane spot radius of 5-100μm, spot shaping uniformity Rs>95%, scanning speed of 1-10000mm / s, repetition frequency of 1-1000kHz, and energy density of 0.1-1J / cm². 2 .

[0040] Specifically, the laser serves two purposes: first, to create grooves in the deposited barrier layer, providing an electrical contact pathway for the subsequent growth of the metal electrode; and second, to provide energy for the metal source film deposited in the modified seed layer, enabling the selective doping and activation of the transparent conductive oxide.

[0041] In some embodiments of the present invention, in step (3), the metal being electroplated is selected from at least one of copper, silver, nickel, aluminum, and tin.

[0042] In some embodiments of the present invention, the electroplating step includes: placing the solar cell precursor modified in step (2) in an electroplating tank, introducing an electroplating solution and placing a metal anode plate, and performing metal electroplating using a three-electrode system. Wherein: the working electrode is connected to the solar cell precursor, the metal anode plate is connected to the counter electrode, and Ag / AgCl is used as the reference electrode.

[0043] In some embodiments of the present invention, the electroplating solution contains sulfuric acid (H2SO4) and copper ions (Cu). 2+ ), chloride ions (Cl) - ) and leveling additives.

[0044] In some embodiments of the present invention, the electroplating may be performed as single electroplating, multiple electroplating, or pulse electroplating.

[0045] A second aspect of the present invention provides a solar cell metal electrode, which is prepared by the above-described method for preparing a solar cell metal electrode. The solar cell metal electrode includes a solar cell precursor, on the surface of which a modified seed layer, a barrier layer and a metal electrode layer are sequentially deposited. The modified seed layer is formed by metal deposition, and the metal is doped in the solar cell precursor.

[0046] Specifically, the solar cell metal electrode of the present invention selectively dops the solar cell precursor with metal atoms in the seed layer, thereby controlling the band structure of the solar cell precursor in the metal contact region and improving the overall performance of the solar cell.

[0047] A third aspect of the present invention provides a solar cell comprising the aforementioned solar cell metal electrode.

[0048] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages:

[0049] (1) The method for preparing the metal electrode of the solar cell of the present invention improves the traditional metal electroplating method by introducing a laser-modified seed layer step. Through selective doping of metal atoms in the seed layer, the TCO band structure is controlled in the metal contact area, thereby improving the overall performance of the solar cell.

[0050] (2) The method for preparing the metal electrode of the solar cell of the present invention does not require the mask layer stripping and seed layer selective etching in the traditional process, which simplifies the metal electroplating process and can be better compatible with the current solar cell preparation process, providing a new idea for the large-scale application of electroplating technology. Attached Figure Description

[0051] Figure 1 This is a schematic diagram illustrating the working principle of the metal electrode of the solar cell of the present invention;

[0052] Figure 2 This is a schematic diagram of the preparation steps of the solar cell metal battery of the present invention;

[0053] Figure 3 This is a schematic diagram of the structure of the solar cell precursor of Embodiments 1-2 of the present invention;

[0054] Figure 4 The electrode pattern of the modified seed layer in Embodiment 1 of the present invention;

[0055] Figure 5 This is a schematic diagram of the patterned deposition modified seed layer method of Embodiment 1 of the present invention. Detailed Implementation

[0056] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0057] Example 1

[0058] A method for fabricating a solar cell, the steps of which are illustrated in the diagram below. Figure 2 As shown, it includes the following steps:

[0059] S1. Preparation of SHJ battery precursor: Specific structure as follows Figure 3 As shown in Figure a, the battery structure is composed of aluminum-doped zinc oxide-based transparent conductive oxide (AZO) / P-type hydrogenated amorphous silicon (pa-Si:H) / intrinsic hydrogenated amorphous silicon (ia-Si:H) / crystalline silicon (c-Si) / N-type hydrogenated amorphous silicon (na-Si:H) / intrinsic hydrogenated amorphous silicon (ia-Si:H) / aluminum-doped zinc oxide-based transparent conductive oxide (AZO). Both the front and back sides of this battery structure have random pyramidal structures with a height of 900-1500 nm. The aluminum-doped zinc oxide-based transparent conductive oxide (AZO) is prepared using reactive plasma deposition technology and has a thickness of 105 nm.

[0060] S2. Patterned deposition of modified seed layers on the upper and lower surfaces of the precursor prepared in S1, using laser transfer (e.g., Figure 5b) Implementation, the specific steps are as follows: First, deposit an Al-modified seed layer source film on two polyethylene terephthalate (PET) films, controlling the film thickness to be 50-100 nm; then, directly contact the PET films with deposited active films above the electron transport end and hole transport end of the SHJ precursor, respectively; finally, use a customized laser marking system with a rated power of 500 W and a 1064 nm infrared continuous laser, and control the heat-affected zone (spot) on the focal plane to 10 μm using a beam expander. Import the designed modified seed layer pattern (e.g., ...) into the laser marking software control terminal. Figure 4 The laser flux was set to 0.5 J / cm. 2 The laser scanning speed is 10 mm / s.

[0061] S3. Fix the precursor treated in S2 onto a carrier plate, and at a temperature of 150°C, use nitrous oxide (N2O) as the main reactant gas to deposit a SiOx thin film with a thickness of 100±10nm on the upper and lower surfaces of the precursor using PEVCVD, wherein the band gap of the SiOx thin film is 4.2eV and the refractive index is 1.5.

[0062] S4. Laser-Modified TCO: A customized laser marking system using a 500W ultraviolet nanosecond laser with a wavelength of 1064nm. A beam expander controls the heat-affected zone (spot) on the focal plane to 10μm. A diffractive optical element (DOE) shapes the Gaussian beam into a flat-top beam with uniformity Rs > 90%. The laser scanning speed is 5000mm / s, and the laser flux is 0.15J / cm². 2 Alignment is achieved using pre-defined Mark points, followed by scanning along the original design pattern.

[0063] S5. Copper Electrode Deposition: An electroplating solution is circulated into the electroplating tank, and a copper plate is placed inside. A standard three-electrode system is used for electroplating. The working electrode is connected to a silicon wafer, and Ag / AgCl is used as the reference electrode. The silicon wafer is electroplated twice: the first electroplating current is 0.4 A for 20 min, and the second electroplating current is 0.2 A for 2 min. The electroplating solution formulation is: 50 g / L Cu under pH < 1 conditions. 2 + 100 g / L H2SO4, 50 ppm Cl - And 3 mL / L of leveling additive (9000E). Rinse the silicon wafer surface with deionized water for 2 min and cure in an oven at 170°C for 30 min.

[0064] Example 2

[0065] A method for fabricating a solar cell includes the following steps:

[0066] S1. Preparation of TOPCon battery precursor: Specific structure as follows Figure 3 As shown in b, this cell structure is an aluminum-doped zinc oxide-based transparent conductive oxide (AZO) / P-type hydrogenated polycrystalline silicon (p-poly-Si:H) / silicon oxide (SiO2) / N-type crystalline silicon (nc-Si) / silicon oxide (SiOx) / N-type hydrogenated polycrystalline silicon (n-poly-Si:H) / silicon nitride (SiNx). The hole transport end of this cell features a random pyramid structure with a height of 900-1500 nm. The aluminum-doped zinc oxide-based transparent conductive oxide (AZO) is prepared using reactive plasma deposition and has a thickness of 105 nm.

[0067] S2. A modified seed layer is deposited at the hole transport end of the precursor prepared in S1, and then transferred using a laser transfer method (e.g., Figure 5 b) Implementation, the specific steps are as follows: First, deposit Al-modified seed layer source films on two polyethylene terephthalate (PET) films, controlling the film thickness to 50-100 nm; then, directly contact the PET films with deposited active films above the hole transport end of the SHJ precursor; finally, use a customized laser marking system with a rated power of 500 W and a 1064 nm infrared continuous laser, and control the heat-affected zone (spot) on the focal plane to 10 μm using a beam expander. Import the designed modified seed layer pattern (e.g., ...) into the laser marking software control terminal. Figure 4 The laser flux was set to 0.5 J / cm. 2 The laser scanning speed is 10 mm / s.

[0068] S3. Fix the precursor treated in S2 onto a carrier plate, and at a temperature of 150°C, use nitrous oxide (N2O) as the main reactant gas to deposit a SiOx thin film with a thickness of 100±10nm on the hole transport end of the precursor using PEVCVD, wherein the band gap of the SiOx thin film is 4.2eV and the refractive index is 1.5.

[0069] S4. Laser-Modified TCO: A customized laser marking system using a 500W ultraviolet nanosecond laser with a wavelength of 1064nm. A beam expander controls the heat-affected zone (spot) on the focal plane to 10μm. A diffractive optical element (DOE) shapes the Gaussian beam into a flat-top beam with uniformity Rs > 90%. The laser scanning speed is 5000mm / s, and the laser flux is 0.15J / cm². 2 Alignment is achieved using pre-defined Mark points, followed by scanning along the original design pattern.

[0070] S5. Copper Electrode Deposition: An electroplating solution is circulated into the electroplating tank, and a copper plate is placed inside. A standard three-electrode system is used for electroplating. The working electrode is connected to a silicon wafer, and Ag / AgCl is used as the reference electrode. The silicon wafer is electroplated twice: the first electroplating current is 0.4 A for 20 min, and the second electroplating current is 0.2 A for 2 min. The electroplating solution formulation is: 50 g / L Cu under pH < 1 conditions. 2 + 100 g / L H2SO4, 50 ppm Cl - And 3 mL / L of leveling additive (9000E). Rinse the silicon wafer surface with deionized water for 2 min and cure in an oven at 170°C for 30 min.

[0071] Example 3

[0072] The difference between Example 3 and Example 1 lies in steps S2 and S4. Step S2 in Example 3 is: using screen printing (e.g., Figure 5 a) Pattern and deposit Al-modified seed layers with a thickness of 1-1.5 μm on the upper and lower surfaces of the precursor prepared in S1. Step S4 of Example 3 is as follows: Set the scanning speed of the infrared quasi-continuous laser to 500 mm / s and the energy density to 0.3 J / cm². 2 .

[0073] Example 4

[0074] The difference between Example 4 and Example 2 lies in steps S2 and S4. Step S2 in Example 4 is: using screen printing (e.g., Figure 5 a) Patterned deposition of Al-modified seed layers with a thickness of 1-1.5 μm on the upper and lower surfaces of the precursor prepared in S1. Step S4 of Example 4 is as follows: The scanning speed of the infrared quasi-continuous laser is set to 500 mm / s, and the energy density is 0.3 J / cm². 2 .

[0075] Example 5

[0076] The difference between Example 5 and Example 1 lies in steps S2 and S4. Step S2 in Example 5 is: using screen printing (e.g., Figure 5 a) Pattern and deposit Al-modified seed layers with a thickness of 2.5-3 μm on the upper and lower surfaces of the precursor prepared in S1. Step S4 of Example 5 is as follows: Set the scanning speed of the infrared quasi-continuous laser to 10 mm / s and the energy density to 0.2 J / cm². 2 .

[0077] Example 6

[0078] The difference between Example 6 and Example 1 lies in steps S3 and S4. In Example 6, step S3 involves depositing silicon oxide at the hole transport end with a thickness of 30 ± 10 nm. Step S4 in Example 6 involves setting the scanning speed of the infrared quasi-continuous laser to 5000 mm / s and the energy density to 0.12 J / cm². 2 .

[0079] Example 7

[0080] The difference between Example 7 and Example 1 lies in steps S3 and S4. In Example 7, step S3 involves depositing silicon oxide at the hole transport end with a thickness of 130 ± 10 nm. Step S4 in Example 7 involves setting the scanning speed of the infrared quasi-continuous laser to 8000 mm / s and the energy density to 0.12 J / cm². 2 .

[0081] Example 8

[0082] The difference between Example 8 and Example 1 lies in steps S3 and S4. In Example 8, step S3 involves depositing alumina at the hole transport end using an ALD with a thickness of 30 ± 10 nm. Step S4 in Example 8 involves setting the scanning speed of the infrared quasi-continuous laser to 7000 mm / s and the energy density to 0.18 J / cm². 2 .

[0083] Example 9

[0084] The difference between Example 9 and Example 1 lies in steps S3 and S4. In Example 9, step S3 involves depositing alumina at the hole transport end using an ALD with a thickness of 100 ± 10 nm. Step S4 in Example 9 involves setting the scanning speed of the infrared quasi-continuous laser to 5000 mm / s and the energy density to 0.2 J / cm². 2 .

[0085] Example 10

[0086] The difference between Example 10 and Example 1 lies in steps S3 and S4. In Example 10, step S3 involves depositing alumina at the hole transport end using an ALD with a thickness of 130 ± 10 nm. Step S4 in Example 10 involves setting the scanning speed of the infrared quasi-continuous laser to 4500 mm / s and the energy density to 0.2 J / cm². 2 .

[0087] Example 11

[0088] The difference between Example 11 and Example 1 lies in steps S3 and S4. Step S3 in Example 11 involves depositing silicon oxynitride with a thickness of 30 ± 10 nm at the hole transport end using PECVD. Step S4 in Example 11 involves setting the scanning speed of the infrared quasi-continuous laser to 8000 mm / s and the energy density to 0.12 J / cm². 2 .

[0089] Example 12

[0090] The difference between Example 12 and Example 1 lies in steps S3 and S4. In Example 12, step S3 involves depositing silicon oxynitride at the hole transport end using PECVD with a thickness of 100 ± 10 nm. Step S4 in Example 12 involves setting the scanning speed of the infrared quasi-continuous laser to 6000 mm / s and the energy density to 0.12 J / cm². 2 .

[0091] Example 13

[0092] The difference between Example 13 and Example 1 lies in steps S3 and S4. In Example 13, step S3 involves depositing silicon oxynitride with a thickness of 130 ± 10 nm at the hole transport end using PECVD. Step S4 in Example 13 involves setting the scanning speed of the infrared quasi-continuous laser to 5000 mm / s and the energy density to 0.12 J / cm². 2 .

[0093] Example 14

[0094] The difference between Example 14 and Example 1 lies in steps S1, S2, and S4. In Example 14, step S1 involves using tantalum-doped tin oxide (TTO) as the transparent conductive oxide on the precursor. In Example 14, step S2 involves depositing a seed layer of metallic tantalum (Ta) on the precursor. In Example 14, step S4 involves setting the scanning speed of the infrared quasi-continuous laser to 2 mm / s and the energy density to 0.95 J / cm². 2 .

[0095] Example 15

[0096] The difference between Example 15 and Example 1 lies in steps S1, S2, and S4. In Example 15, step S1 involves using indium tin oxide (ITO) as the transparent conductive oxide on the precursor. In Example 15, step S2 involves depositing an indium (In) seed layer on the precursor. In Example 15, step S4 involves setting the scanning speed of the infrared quasi-continuous laser to 9000 mm / s and the energy density to 0.1 J / cm². 2 .

[0097] Example 16

[0098] The difference between Example 16 and Example 1 lies only in step S4. Step S4 of Example 16 is as follows: A green picosecond laser (<15 ps) with a wavelength of 532 nm is used, with a rated repetition rate of 500-1000 kHz, a rated power of 30 W, a scanning speed of 1000 mm / s, and an energy density of 0.4 J / cm². 2 .

[0099] Example 17

[0100] The difference between Example 17 and Example 1 lies only in step S4. Step S4 of Example 17 is as follows: A green nanosecond (<20ns) laser with a wavelength of 532nm is used, with a rated repetition rate of 50-300kHz, a rated power of 25W, a scanning speed of 1000mm / s, and an energy density of 0.8J / cm². 2 .

[0101] Example 18

[0102] The difference between Example 18 and Example 1 lies only in step S4. Step S4 in Example 18 is as follows: A 355nm ultraviolet picosecond (<15ps) laser is used, with a rated repetition rate of 500-1000kHz, a rated power of 30W, a scanning speed of 1000mm / s, and an energy density of 0.2J / cm². 2 .

[0103] Example 19

[0104] The difference between Example 19 and Example 1 lies only in step S4. Step S4 in Example 19 is as follows: A 355nm ultraviolet nanosecond (<20ns) laser is used, with a rated repetition rate of 50-300kHz, a rated power of 25W, a scanning speed of 1000mm / s, and an energy density of 0.6J / cm². 2 .

[0105] Example 20

[0106] The difference between Example 19 and Example 1 lies only in step S4. In Example 19, step S4 involves two laser steps: laser grooving of the barrier layer and laser modification of the TCO, respectively. The first laser step uses an infrared quasi-continuous laser with a scanning speed of 6300 mm / s and an energy density of 0.1 J / cm². 2 The second step involves setting the infrared quasi-continuous laser scanning speed to 1000 mm / s and the energy density to 0.2 J / cm². 2 ;

[0107] Example 21

[0108] The difference between Example 21 and Example 1 lies in steps S2 and S4. In Example 12, step S2 involves setting the laser spot size to 50 μm during laser transfer. In Example 12, step S4 involves adjusting the laser spot size to 50 μm, setting the scanning speed of the infrared quasi-continuous laser to 5000 mm / s, and the energy density to 0.15 J / cm². 2 .

[0109] Example 22

[0110] The difference between Example 22 and Example 1 lies in steps S2 and S4. In Example 22, step S2 involves setting the laser spot size to 100 μm during laser transfer. In Example 12, step S4 involves adjusting the laser spot size to 100 μm, setting the scanning speed of the infrared quasi-continuous laser to 5000 mm / s, and the energy density to 0.15 J / cm². 2 .

[0111] Comparative Example 1

[0112] A method for fabricating a solar cell, employing a traditional copper electroplating method, includes the following steps:

[0113] S1. Preparation of SHJ battery precursor: Specific structure as follows Figure 3 As shown in Figure a, the battery structure is composed of aluminum-doped zinc oxide-based transparent conductive oxide (AZO) / P-type hydrogenated amorphous silicon (pa-Si:H) / intrinsic hydrogenated amorphous silicon (ia-Si:H) / crystalline silicon (c-Si) / N-type hydrogenated amorphous silicon (na-Si:H) / intrinsic hydrogenated amorphous silicon (ia-Si:H) / aluminum-doped zinc oxide-based transparent conductive oxide (AZO). Both the front and back sides of this battery structure have random pyramidal structures with a height of 900-1500 nm. The aluminum-doped zinc oxide-based transparent conductive oxide (AZO) is prepared using reactive plasma deposition technology and has a thickness of 105 nm.

[0114] S2. The upper and lower surfaces of the battery precursor in S1 are covered with photomasks, which are then fixed together on a carrier plate and fed into a PVD apparatus to deposit an Al seed layer, wherein the seed layer has a height of 100 nm. The function of the seed layer is to provide electrical contact for the growth of the copper electrode and to enhance the electrode adhesion.

[0115] S3. Spin-coat photoresist (AZ 3027) on the upper and lower surfaces of the silicon wafer. Spin-coat for 2 min for the first time, 3 min for the second time, and 5 min for the third time to finally obtain a photoresist mask layer of about 4 μm.

[0116] S4. Use the mask from S2 to expose the silicon wafer four times, each exposure lasting 25 seconds, with an exposure interval of 10 seconds.

[0117] S5. Clean the exposed silicon wafer for 1 minute using MF322 solvent and deionized water. The purpose of exposure and cleaning is to pattern the photoresist deposited over the entire area, provide a pathway for the growth of copper electrodes, and prevent leakage during the deposition process.

[0118] S6. Electroplating solution is introduced into the electroplating tank, and a copper plate is placed inside. A standard three-electrode system is used for electroplating, with the working electrode connected to a silicon wafer and Ag / AgCl used as the reference electrode. The silicon wafer is electroplated twice: the first electroplating current is 0.4 A for 20 min, and the second electroplating current is 0.2 A for 2 min. The electroplating solution formulation is: 50 g / L Cu under pH < 1 conditions. 2+ 100 g / L H2SO4, 50 ppm Cl - And 3 mL / L of leveling additive (9000E).

[0119] S7. Use acetone to peel off the photoresist from the silicon wafer surface.

[0120] S8. Rinse the silicon wafer surface with deionized water for 2 minutes, and then cure it in an oven at 170°C for 30 minutes.

[0121] Comparative Example 2

[0122] The only difference between Comparative Example 2 and Comparative Example 1 is the step S1. The step S1 of Comparative Example 2 is the same as the step S1 of Example 2.

[0123] Performance testing

[0124] The performance of the solar cells prepared in Examples 1-22 and Comparative Examples 1-2 were tested using a Weixin VS6831S-PSCs IV testing machine. The ambient temperature during testing was 25±2℃, and the cell size was 2×2cm. 2 The electrode coverage was 4.5%, and the test results are shown in Table 1.

[0125] Table 1:

[0126]

[0127] As shown in Table 1, the solar cells prepared in Examples 1-22 have open-circuit voltages of 724.7-7.9.1 mV, fill factors of 82.9-85.5, and short-circuit current densities of 40.17-41.77 mA / cm². 2 The photoelectric conversion efficiency is 24.65-25.49%, exhibiting good overall battery performance. Furthermore, the photoelectric conversion efficiencies of the solar cells prepared in Examples 1-2 are 25.27% and 25.49%, respectively, representing improvements of 0.66% and 0.82% compared to the photoelectric conversion efficiencies of 24.61% and 24.67% achieved by the conventional copper electroplating method in Comparative Examples 1-2.

[0128] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A method for preparing a metal electrode for a solar cell, characterized in that, Includes the following steps: (1) A modified seed layer and a barrier layer are sequentially patterned and deposited on the surface of the solar cell precursor, and CCD alignment Mark points are reserved during the patterned deposition of the modified seed layer. (2) Positioning and alignment are performed using the Mark points, and the area of ​​the modified seed layer is scanned with a laser to perform laser grooving and laser modification; (3) Electroplating is used to deposit metal electrodes on the solar cell precursor modified in step (2) to obtain the solar cell metal electrode.

2. The method for preparing a solar cell metal electrode according to claim 1, characterized in that, In step (1), the modified seed layer is formed by metal deposition, wherein the metal is selected from at least one of silver, aluminum, magnesium, vanadium, manganese, chromium, yttrium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, tin, indium, gallium, zinc, nickel, and titanium.

3. The method for preparing a solar cell metal electrode according to claim 1 or 2, characterized in that, The deposition method of the modified seed layer is selected from laser transfer or screen printing; and / or, the thickness of the modified seed layer is 10nm-3μm.

4. The method for preparing a solar cell metal electrode according to claim 1, characterized in that, In step (1), the barrier layer is formed by depositing at least one of oxides, nitrides, and oxynitrides.

5. The method for preparing a solar cell metal electrode according to claim 1 or 4, characterized in that, The barrier layer is deposited using a method selected from plasma-enhanced chemical vapor deposition or atomic layer deposition; and / or, the thickness of the barrier layer is 20-150 nm.

6. The method for preparing a solar cell metal electrode according to claim 1, characterized in that, In step (1), the solar cell precursor includes a transparent conductive oxide layer, a hole or electron passivation contact layer, a doped crystalline silicon layer, a hole or electron passivation contact layer, a transparent conductive oxide layer or a passivation antireflection layer stacked sequentially; the transparent conductive oxide layer is selected from any one of aluminum, gallium, tin, tungsten, tantalum or cerium doped with indium oxide, tin oxide, zinc oxide, titanium oxide, gallium oxide or cadmium oxide, and the thickness of the transparent conductive oxide layer is 10-200 nm.

7. The method for preparing a solar cell metal electrode according to claim 1, characterized in that, In step (2), the parameters of the laser scanning are as follows: the wavelength is 355 - 1064 nm, the pulse width is 1 ps - 100 μs, the power is 25 - 500 W, the focal plane spot radius is 5 - 100 μm, the spot shaping uniformity Rs > 95%, the scanning speed is 1 - 10000 mm / s, the repetition frequency is 1 - 1000 kHz, and the energy density is 0.1 - 1 J / cm 2 .

8. The method for preparing a solar cell metal electrode according to claim 1, characterized in that, In step (3), the metal being electroplated is selected from at least one of copper, silver, nickel, aluminum, and tin.

9. A metal electrode for a solar cell, characterized in that, The solar cell metal electrode is prepared by the method of any one of claims 1-8; the solar cell metal electrode includes a solar cell precursor, wherein a modified seed layer, a barrier layer and a metal electrode layer are sequentially deposited on the surface of the solar cell precursor; the modified seed layer is formed by metal deposition, and the metal is doped in the solar cell precursor.

10. A solar cell, characterized in that, Includes the solar cell metal electrode as described in claim 9.

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