Metal gate line electrode, method of manufacturing the same, and application thereof

Abstract

This invention belongs to the field of metal electrode technology and discloses a metal grid electrode, its preparation method, and its application. The preparation method of the metal grid electrode includes the following steps: first, depositing a titanium-based compound on the surface of a conductive substrate to form a titanium-based transition layer; then, forming a hydrophobic protective mask on the SAM of the titanium-based transition layer; next, performing laser patterning treatment on the surface of the hydrophobic protective mask to remove the self-assembled monolayer within the laser-acting region, and partially removing and modifying the transition layer to form a laser-patterned region; finally, electroplating metal grid lines in the laser-patterned region. This invention, by introducing a highly conductive titanium-based transition layer, optimizes the electroplating current distribution and, in conjunction with SAM, suppresses parasitic electroplating, significantly improving the aspect ratio of the metal grid lines. The aspect ratio of the metal grid lines can be stably maintained above 0.30, and the preparation process is simple and the production cost is low.

Description

Technical Field

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

[0002] With the rapid development of the photovoltaic industry, reducing the production cost of solar cells and improving conversion efficiency have become research hotspots. The metallization process, as a key step in solar cell manufacturing, accounts for a high proportion of costs, with silver paste consumption being one of the main sources of these costs. Replacing silver with copper as the metal grid material is an effective way to reduce costs, but traditional copper electroplating processes require complex photolithography masking procedures, including full-area seed layer deposition, photolithography mask coating, exposure, development, electroplating, and stripping, making the process lengthy and costly.

[0003] In recent years, photolithography-free metallization technology has attracted widespread attention due to its potential to simplify processes and reduce costs. For example, a Chinese invention patent (publication number CN 119947298 A) discloses a method for fabricating metal electrodes using laser grooving combined with a mask layer. Although this method simplifies the process, the height of the electrodes it fabricates is limited, and the aspect ratio (height / width) is usually low, making it difficult to meet the requirements of high-performance solar cells for low series resistance and high fill factor. Problems such as insufficient lateral conductivity of transparent conductive oxide (TCO) substrates, severe erosion of the substrate by acidic electroplating solutions, and difficulty in suppressing parasitic plating make it difficult to break through the grid line aspect ratio of 0.15, thus limiting further improvements in cell performance.

[0004] Therefore, there is an urgent need to develop a new method for fabricating metal electrodes to improve the aspect ratio of the metal electrodes, thereby improving the performance of the devices. Summary of the Invention

[0005] This invention aims to solve the technical problems of low gate line aspect ratio and poor metallization selectivity caused by insufficient substrate conductivity, severe parasitic electroplating, and easy erosion of the substrate by the electroplating solution in the photolithography-free metallization process. It proposes a metal gate line electrode, its preparation method and application. The metal gate line electrode has a high aspect ratio, which can reach more than 0.30.

[0006] To address the aforementioned technical problems, a first aspect of the present invention provides a method for preparing a metal grid electrode, comprising the following steps: (1) A titanium-based compound is deposited on the surface of a conductive substrate to form a titanium-based transition layer; (2) A monolayer is self-assembled on the surface of the titanium-based transition layer to form a hydrophobic protective mask; (3) Laser patterning is performed on the surface of the hydrophobic protective coating so that the self-assembled monolayer in the laser action area is completely removed and the titanium-based transition layer is partially removed and modified to form a laser patterned area. (4) Electroplating metal grid lines in the laser patterned area to obtain the metal grid line electrode.

[0007] The core inventive concept of the method for fabricating the metal gate electrode of the present invention is as follows: a combination of a self-assembled monolayer and a titanium-based transition layer is adopted. On the one hand, a titanium-based transition layer is introduced, which is laser-reduced to generate a titanium metal seed layer. The seed layer and the unreduced titanium-based transition layer together enhance the lateral conductivity of the conductive substrate and protect the substrate from electroplating solution corrosion. On the other hand, the self-assembled monolayer (SAM) suppresses parasitic electroplating in non-target areas. The combination of the two improves the electroplating selectivity, and combined with laser patterning technology, the aspect ratio of the metal gate line is improved.

[0008] Specifically, a titanium-based transition layer is first deposited on the surface of a conductive substrate. This transition layer not only significantly enhances the lateral conductivity of the conductive substrate and improves the efficiency of electroplating current conduction, but also acts as a physical barrier to effectively protect the underlying conductive substrate from corrosion by acidic electroplating solutions. Then, a self-assembled monolayer is formed on the surface of the titanium-based transition layer as a superhydrophobic protective mask to suppress parasitic electroplating in unpatterned areas. Next, a laser is used to selectively remove the SAM in specific areas and modify the titanium-based transition layer in those areas (i.e., the titanium-based material in the transition layer is reduced to metallic titanium using a laser, serving as a seed layer to make the laser-treated area more conductive than the untreated area, thus facilitating subsequent electroplating of the metal electrode), forming a laser-patterned area for electroplating. Finally, electroplating is performed on the laser-treated conductive substrate. Because the titanium-based transition layer enhances lateral conductivity and the SAM effectively suppresses parasitic plating, the current concentrates in the laser-treated area, achieving high selectivity and high longitudinal growth of the gate line, thereby obtaining a metal gate electrode with a high aspect ratio.

[0009] In some embodiments of the present invention, in step (3), the thickness of the titanium-based transition layer removed accounts for 10-80% of the total thickness.

[0010] In some embodiments of the present invention, in step (3), the thickness of the titanium-based transition layer removed accounts for 20-50% of the total thickness.

[0011] In some embodiments of the present invention, the titanium-based transition layer satisfies at least one of the following characteristics: 1) Thickness is 5-500nm; 2) Carrier concentration is 1×10 20 -5×10 22 cm -3 ; 3) The migration rate is 0.1-50cm 2 ·V -1 ·s -1 ; 4) Contains titanium-based material and doping elements, wherein the titanium-based material is selected from at least one of titanium, titanium oxide, titanium nitride, and titanium carbide, and the doping element is selected from one of niobium, tantalum, samarium, strontium, antimony, arsenic, bismuth, carbon, nitrogen, aluminum, and fluorine, and the doping amount of the doping element is 0-30 at.

[0012] In some embodiments of the present invention, the titanium-based transition layer satisfies at least one of the following characteristics: 1) Thickness is 30-120nm; 2) Carrier concentration is 5×10 20 -2×10 22 cm -3 ; 3) The migration rate is 8-24cm 2 ·V -1 ·s -1 ; 4) Contains titanium-based material and doping elements, wherein the titanium-based material is selected from titanium oxide, and the doping element is selected from one of niobium, tantalum, samarium, strontium, antimony, arsenic, bismuth, carbon, nitrogen, aluminum, and fluorine, and the doping amount of the doping element is 0-30 at.

[0013] For the metal grid electrode of this invention, its transition layer material needs to simultaneously meet multiple performance requirements, including conductivity, chemical stability, and interfacial compatibility with the self-assembled monolayer. Research has found that titanium-based compounds, especially titanium oxide, can cover the self-assembled monolayer and maintain stability and high conductivity even after laser patterning, thus supporting subsequent selective electroplating.

[0014] In some embodiments of the present invention, the sheet resistance of the titanium-based transition layer after laser modification is 50-500 Ω / sq.

[0015] In some embodiments of the present invention, the sheet resistance of the titanium-based transition layer after laser modification is 100-300 Ω / sq.

[0016] In some embodiments of the present invention, the material of the self-assembled monolayer is selected from at least one of phosphonic acid compounds, silane compounds, and thiol compounds.

[0017] In some embodiments of the present invention, the material of the self-assembled monolayer is selected from at least one of octadecylphosphonic acid (ODPA) and tetradecylphosphonic acid (ADPA).

[0018] Compared with traditional organic or inorganic masks, the self-assembled monolayer used in this invention has the following advantages: Firstly, its thickness is extremely thin, and its impact on the overall optical transmittance and light absorption behavior of the device is negligible. Therefore, no additional removal steps are required, avoiding additional process complexity and potential damage to the device surface. Secondly, it does not introduce obvious step structures, which is conducive to the concentration of current in the patterned area during electroplating and can effectively improve the interface resistance in the non-patterned area, thereby significantly suppressing parasitic electroplating behavior. This allows the electroplating current to be mainly concentrated in the laser processing area, which is conducive to the continuous growth of metal in the vertical direction, thereby increasing the height and aspect ratio of the gate line.

[0019] Meanwhile, the self-assembled monolayer of this invention differs fundamentally from traditional physical masks. It is an interface control layer with selective electroplating capability constructed at the nanoscale by forming a stable interface bond with the surface of the titanium-based transition layer. This mask does not limit the electroplating area through physical blocking, but rather suppresses the electroplating reaction in non-patterned areas by controlling the interface wettability and interfacial electrochemical behavior.

[0020] In some embodiments of the present invention, the formation process of the hydrophobic protective mask is as follows: immersing a conductive substrate with a titanium-based transition layer deposited in a single-molecule solution with a concentration of 0.01-20 mmol / L and allowing it to stand for 0.5-30 hours.

[0021] In some embodiments of the present invention, the formation process of the hydrophobic protective mask is as follows: immersing a conductive substrate with a titanium-based transition layer deposited in a single-molecule solution with a concentration of 0.5-1 mmol / L and letting it stand for 13-17 hours.

[0022] In some embodiments of the present invention, the parameters of the laser patterning process satisfy at least one of the following parameters: 1) The laser wavelength is 355-1064nm; 2) Laser scanning speed is 1-7000 mm / s; 3) The laser scanning frequency is 5-500kHz; 4) The instantaneous peak power or equivalent average power of the laser output is 0.001-1000W. 5) Laser energy density is 0.01~50 J / cm² 2 ; 6) The diameter of the laser spot is 1-80μm.

[0023] In some embodiments of the present invention, the parameters of the laser patterning process satisfy at least one of the following parameters: 1) The laser wavelength is 355-455nm; 2) The laser scanning speed is 4000-6000 mm / s; 3) The laser scanning frequency is 20-300kHz; 4) The instantaneous peak power or equivalent average power of the laser output is 0.01-100W. 5) The laser energy density is 0.05-5 J / cm². 2 ; 6) The laser spot diameter is 5-40μm.

[0024] In some embodiments of the present invention, the electroplating is performed by direct current electroplating or pulsed reverse electroplating, and the electroplating is performed at a potential of 0V to -3V for 5-60 minutes.

[0025] In some embodiments of the present invention, the material of the metal grid wire is a conductive metal, which is selected from at least one of silver, aluminum, copper, iron, and nickel.

[0026] In some embodiments of the present invention, the width of the metal grid line is 1-50 μm, the height is >10 μm, and the aspect ratio is ≥0.25.

[0027] A second aspect of the present invention provides a metal grid electrode, which is prepared by the above-described method for preparing a metal grid electrode.

[0028] A third aspect of the present invention provides a photovoltaic device including the aforementioned metal grid electrode.

[0029] In some embodiments of the present invention, the photovoltaic device includes a photovoltaic cell.

[0030] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) The method for preparing metal grid line electrodes provided by the present invention optimizes the electroplating current distribution by introducing a highly conductive titanium-based transition layer and synergistically suppresses parasitic electroplating with SAM, significantly improving the aspect ratio of the metal grid line and achieving a stable aspect ratio of over 0.30 for the metal grid line.

[0031] (2) The metal grid electrode preparation method provided by the present invention greatly suppresses parasitic electroplating in non-target areas through the synergistic effect of titanium-based transition layer and SAM, so that metal deposition is highly concentrated in the grid area, improving metallization selectivity and ensuring the uniformity and high precision of grid morphology.

[0032] (3) The method for preparing metal grid electrodes provided by the present invention utilizes the chemical properties of the titanium-based transition layer to stabilize and enhance substrate protection, effectively resisting the erosion of acidic electroplating solution, protecting the integrity of the underlying functional layer, and improving the reliability of the device.

[0033] (4) The method for preparing metal grid electrodes provided by the present invention uses laser direct writing technology to replace traditional photolithography, which eliminates multiple cumbersome steps such as coating, exposure, and development, shortens the process to four core steps, simplifies the process, and significantly reduces the cost of equipment and materials. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the process for fabricating the metal grid electrode of the present invention; Figure 2 The height-width curve of the metal grid electrode prepared in Example 3 of the present invention. Detailed Implementation

[0035] 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.

[0036] Figure 1 This is a schematic diagram of the fabrication process of the metal grid electrode of the present invention. Figure 1 As can be seen, the method for preparing the metal gate electrode of the present invention mainly includes the following steps: S1. Depositing a titanium-based compound transition layer on the surface of a conductive substrate; S2. Self-assembling a monolayer (SAM) on the surface of the titanium-based transition layer; S3. Laser patterning treatment on the surface of the self-assembled monolayer to form a laser-patterned region; S4. Electroplating gate lines in the laser-patterned region.

[0037] The following will refer to Figure 1 The methods for preparing the metal grid electrodes in the examples and comparative examples are described.

[0038] Example 1 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate, wherein the titanium-based transition layer is a tantalum-doped titanium oxide thin film with a thickness of 30 nm and a carrier concentration of 5 × 10⁻⁶. 20 cm -3 The mobility is 8 cm²·V -1 ·s -1 The sheet resistance is 520Ω / sq.

[0039] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 0.5 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 16 hours to form SAM on the surface of titanium-based transition layer.

[0040] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the titanium-based transition layer was partially removed (the thickness of the removed part accounted for 22% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 4500mm / s, frequency 300kHz, power 0.04W, laser energy density 0.07J / cm², and spot diameter 30μm.

[0041] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines are electroplated in the laser patterned area to obtain the metal grid line electrode of this embodiment.

[0042] Example 2 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate, wherein the titanium-based transition layer is a tantalum-doped titanium oxide thin film with a thickness of 50 nm and a carrier concentration of 8 × 10⁻⁶. 20 cm -3 The mobility is 10 cm²·V -1 ·s -1 The sheet resistance is 160Ω / sq.

[0043] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 0.8 mmol / L tetradecylphosphonic acid (ADPA) ethanol solution and left to stand for 20 hours to form SAM on the surface of titanium-based transition layer.

[0044] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the titanium-based transition layer was partially removed (the thickness of the removed part accounted for 25% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 4800mm / s, frequency 200kHz, power 0.09W, laser energy density 0.12J / cm², and spot diameter 15μm.

[0045] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines are electroplated in the laser patterned area to obtain the metal grid line electrode of this embodiment.

[0046] Example 3 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate. The titanium-based transition layer is a niobium-doped titanium oxide thin film with a thickness of 80 nm and a carrier concentration of 1.2 × 10⁻⁶. 21 cm -3 The migration rate is 7 cm²·V -1 ·s -1 The sheet resistance is 100Ω / sq.

[0047] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 10 hours to form SAM on the surface of titanium-based transition layer.

[0048] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the titanium-based transition layer was partially removed (the thickness of the removed part accounted for 29% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 5000mm / s, frequency 500kHz, power 0.2W, laser energy density 0.2J / cm², and spot diameter 30μm.

[0049] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines are electroplated in the laser patterned area to obtain the metal grid line electrode of this embodiment.

[0050] Example 4 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate, wherein the titanium-based transition layer is a titanium oxide thin film with a thickness of 80 nm and a carrier concentration of 1.0 × 10⁻⁶. 21 cm -3 The mobility is 5 cm²·V -1 ·s -1 The sheet resistance is 160Ω / sq.

[0051] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 10 hours to form SAM on the surface of titanium-based transition layer.

[0052] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the titanium-based transition layer was partially removed (the thickness of the removed part accounted for 34% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 6000mm / s, frequency 400kHz, power 0.18W, laser energy density 0.25J / cm², and spot diameter 25μm.

[0053] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines are electroplated in the laser patterned area to obtain the metal grid line electrode of this embodiment.

[0054] Example 5 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate, wherein the titanium-based transition layer is a titanium oxide thin film with a thickness of 120 nm and a carrier concentration of 6 × 10⁻⁶. 20 cm -3 The mobility is 9 cm²·V -1 ·s -1 The sheet resistance is 105Ω / sq.

[0055] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 16 hours to form SAM on the surface of titanium-based transition layer.

[0056] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the titanium-based transition layer was partially removed (the thickness of the removed part accounted for 43% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 5000mm / s, frequency 400kHz, power 0.21W, laser energy density 0.3J / cm², and spot diameter 40μm.

[0057] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines are electroplated in the laser patterned area to obtain the metal grid line electrode of this embodiment.

[0058] Comparative Example 1 A method for fabricating a metal grid electrode includes the following steps: (1) ITO conductive substrate was immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 10 hours to form SAM on the surface of titanium-based transition layer.

[0059] (2) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser action area was completely removed, forming a laser patterned area. The laser parameters are as follows: scanning speed 5000mm / s, frequency 500kHz, power 0.2W, laser energy density 0.2J / cm², and spot diameter 15μm.

[0060] (3) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines were electroplated in the laser patterned area to obtain the metal grid line electrode of this comparative example.

[0061] The difference between Comparative Example 1 and Example 3 is that SAM is formed directly on the ITO conductive substrate without the step of depositing a titanium-based compound transition layer.

[0062] Electroplating results: Due to the lack of a highly conductive titanium-based transition layer, the ITO substrate has insufficient lateral conductivity, uneven electroplating current distribution, and the acidic electroplating solution has a significant corrosive effect on ITO. After the ITO is removed, the conductivity is further reduced, making electroplating difficult.

[0063] Comparative Example 2 A method for fabricating a metal grid electrode includes the following steps: (1) A tin oxide transition layer is deposited on the surface of an ITO conductive substrate, wherein the thickness of the tin oxide transition layer is 80 nm.

[0064] (2) The ITO conductive substrate with tin oxide transition layer deposited in step (1) is immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 10 hours to form SAM on the surface of titanium-based transition layer.

[0065] (3) A 355nm ultraviolet nanosecond laser was used to pattern the SAM surface, so that the SAM in the laser-acting area was completely removed and the tin oxide transition layer was partially removed (the thickness of the removed part accounted for 29% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 5000mm / s, frequency 500kHz, power 0.2W, laser energy density 0.2J / cm², and spot diameter 15μm.

[0066] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines were electroplated in the laser patterned area to obtain the metal grid line electrode of this comparative example.

[0067] The difference between Comparative Example 2 and Example 3 is that tin oxide is used instead of titanium oxide.

[0068] Electroplating results: Due to the poor conductivity of the tin oxide transition layer, the lateral conductivity of the metallized area formed after laser patterning is insufficient, making it difficult to effectively concentrate the current during electroplating, resulting in electroplating difficulties and the failure to form a clear grid structure.

[0069] Comparative Example 3 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate. The titanium-based transition layer is a niobium-doped titanium oxide thin film with a thickness of 80 nm and a carrier concentration of 1.2 × 10⁻⁶. 21 cm -3 The migration rate is 7 cm²·V -1 ·s -1 The sheet resistance is 100Ω / sq.

[0070] (2) A 355nm ultraviolet nanosecond laser was used to pattern the surface of the titanium-based transition layer, so that the titanium-based transition layer in the laser-acted area was partially removed (the thickness of the removed part accounted for 29% of the total thickness of the titanium-based transition layer) and modified to form a laser-patterned area. The laser parameters were as follows: scanning speed 5000mm / s, frequency 500kHz, power 0.2W, laser energy density 0.2J / cm², and spot diameter 30μm.

[0071] (3) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines were electroplated in the laser patterned area to obtain the metal grid line electrode of this comparative example.

[0072] The difference between Comparative Example 3 and Example 3 is that it does not include step (2) and SAM is not formed.

[0073] Electroplating results: Due to the lack of a SAM protective mask, severe parasitic electroplating occurred on the entire substrate surface during the electroplating process, making it impossible to form a clear gate structure. In the end, the sample surface was covered by an uneven copper film, and the aspect ratio could not be measured.

[0074] Comparative Example 4 A method for fabricating a metal grid electrode includes the following steps: (1) A titanium-based transition layer is deposited on the surface of an ITO conductive substrate, wherein the titanium-based transition layer is a titanium oxide thin film with a thickness of 80 nm and a carrier concentration of 1.2 × 10⁻⁶. 21 cm -3 The mobility is 24 cm²·V -1 ·s -1 The sheet resistance is 190Ω / sq.

[0075] (2) The ITO conductive substrate with titanium-based transition layer deposited in step (1) is immersed in 1 mmol / L octadecylphosphonic acid (ODPA) ethanol solution and left to stand for 10 hours to form SAM on the surface of titanium-based transition layer.

[0076] (3) Use photolithography to pattern the SAM surface so that the SAM in the photolithographic area is removed.

[0077] (4) Using DC electroplating, with a potential of -0.75V and an electroplating time of 25 minutes, copper grid lines were electroplated in the laser patterned area to obtain the metal grid line electrode of this comparative example.

[0078] The difference between Comparative Example 4 and Example 3 is that photolithography is used instead of laser patterning.

[0079] Electroplating results: Since laser was not used to pattern the titanium-based transition layer, no effective selective electroplating area was formed. Removing SAM alone could not concentrate the current density in the patterned area, resulting in a low height of the metal gate line.

[0080] Performance testing The height and width of the metal grid electrodes prepared in Examples 1-5 and Comparative Examples 1-4 were tested, and their aspect ratios (height / width) were calculated. The results are shown in Table 1.

[0081] Table 1:

[0082] As shown in Table 1, the metal grid electrodes prepared in Examples 1-3 all have high aspect ratios, ranging from 0.30 to 1.12. Figure 2 The height-width curve of the metal gate electrode prepared in Example 3 is shown below. Figure 2 It can be seen that the height of the grid line is 19μm, the width is 40μm, and the aspect ratio is 0.48.

[0083] Compared to Example 3, Comparative Examples 1-4, due to the absence of a titanium-based transition layer, the use of a tin oxide transition layer, the absence of SAM, and the lack of patterning modification of the titanium-based transition layer, respectively, could not achieve a superior aspect ratio, or even form a complete gate line structure. This demonstrates that the metal gate line electrode fabrication method of the present invention is a synergistic overall technical solution.

[0084] 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 fabricating a metal grid electrode, characterized in that, Includes the following steps: (1) A titanium-based compound is deposited on the surface of a conductive substrate to form a titanium-based transition layer; (2) A monolayer is self-assembled on the surface of the titanium-based transition layer to form a hydrophobic protective mask; (3) Laser patterning is performed on the surface of the hydrophobic protective coating so that the self-assembled monolayer in the laser action area is completely removed and the titanium-based transition layer is partially removed and modified to form a laser patterned area. (4) Electroplating metal grid lines in the laser patterned area to obtain the metal grid line electrode.

2. The method for preparing the metal grid electrode according to claim 1, characterized in that, The titanium-based transition layer satisfies at least one of the following characteristics: 1) Thickness is 5-500nm; 2) Carrier concentration is 1×10 20 -5×10 22 cm -3 ; 3) The migration rate is 0.1-50cm 2 ·V -1 ·s -1 ; 4) Contains titanium-based material and doping elements, wherein the titanium-based material is selected from at least one of titanium, titanium oxide, titanium nitride, and titanium carbide, and the doping element is selected from one of niobium, tantalum, samarium, strontium, antimony, arsenic, bismuth, carbon, nitrogen, aluminum, and fluorine, and the doping amount of the doping element is 0-30 at.

3. The method for preparing the metal grid electrode according to claim 1, characterized in that, The material of the self-assembled monolayer is selected from at least one of phosphonic acid compounds, silane compounds, and thiol compounds.

4. The method for preparing the metal grid electrode according to claim 1 or 3, characterized in that, The formation process of the hydrophobic protective mask is as follows: immerse the conductive substrate with the deposited titanium-based transition layer in a single-molecule solution with a concentration of 0.01-20 mmol / L and let it stand for 0.5-30 hours.

5. The method for preparing the metal grid electrode according to claim 1, characterized in that, The parameters of the laser patterning process satisfy at least one of the following parameters: 1) The laser wavelength is 355-1064nm; 2) Laser scanning speed is 1-7000 mm / s; 3) The laser scanning frequency is 5-500kHz; 4) The instantaneous peak power or equivalent average power of the laser output is 0.001-1000W; 5) Laser energy density is 0.01~50 J / cm² 2 ; 6) The diameter of the laser spot is 1-80μm.

6. The method for preparing the metal grid electrode according to claim 1, characterized in that, The electroplating is performed using direct current electroplating or pulsed reverse electroplating, and the electroplating time is 5-60 minutes at a potential of 0V to -3V.

7. The method for preparing the metal grid electrode according to claim 1, characterized in that, The metal grid wire is made of conductive metal.

8. The method for preparing the metal grid electrode according to claim 7, characterized in that, The conductive metal is selected from at least one of silver, aluminum, copper, iron, and nickel.

9. A metal grid line electrode, characterized in that, It is prepared by the method of any one of claims 1-8 for preparing metal grid electrodes.

10. A photovoltaic device, characterized in that, Includes the metal grid electrode as described in claim 9.

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