Preparation method and application of small-width linear structure on upper surface of target layer of laminated structure

Abstract

The invention discloses a preparation method and application of a small-width linear structure on the upper surface of a target layer of a laminated structure, and the method for preparing the linear structure comprises the following steps: obtaining preset positions of two sides of the linear structure on the upper surface of the target layer, and recording the preset positions as a first side position and a second side position; a plurality of protrusions are generated on at least one side edge position in a first side edge position and a second side edge position of the upper surface of a target layer in the side edge length direction at intervals, and a protruding line on at least one side edge position is formed; and a liquid type linear structure material is applied to one side of the protruding line, and the linear structure limited to one side of the protruding line is obtained through deposition.

Description

Technical Field

[0001] The present invention relates to the technical field of thin-film solar cells, and particularly to a preparation method and application of a small-width linear structure on the upper surface of a target layer of a stacked structure. Background Art

[0002] Thin-film solar cells have a multi-layer structure. As is known to those skilled in the art, the layer structure of thin-film solar cells at least consists of a substrate, a back electrode layer, an absorption layer, a buffer / i layer, and a front electrode layer, which are arranged in sequence from bottom to top in the substrate structure and vice versa in the superstrate structure, but have the same layers. For large-area thin-film solar cells, in order to avoid high series resistance and subsequent high current loss, the module is usually designed as a series of monolithic interconnected cells. To achieve segmentation and series connection, P1, P2, and P3 lines are respectively arranged on the back electrode layer, the absorption layer, the buffer layer, and the front electrode layer (as Figure 1 shown). Specifically, the preparation method of thin-film solar cells includes the following steps:

[0003] Provide a substrate;

[0004] Deposit a back electrode layer on one side of the substrate;

[0005] Subdivide the back electrode layer through the P1 line;

[0006] Deposit an absorption layer and a buffer / i layer on the back electrode layer in sequence;

[0007] Synchronously subdivide the absorption layer and the buffer / i layer through the P2 line;

[0008] Deposit a front electrode layer on the buffer / i layer; and

[0009] Subdivide the front electrode layer through the P3 line.

[0010] P1 and P3 insulate the back electrode and the front electrode, and P2 serves as an electrical contact between the back electrode and the front electrode for the series connection of two adjacent cells. Since the structural areas of P1 / P2 / P3 do not generate electricity, they are usually referred to as the "dead zones" of solar cells (as Figure 2 and Figure 3 shown). The remaining area is called the effective area of the solar cell.

[0011] To optimize the power conversion efficiency and application performance of a solar cell, it is advantageous to add a linear structure to the upper surface of a layer. Considering that the width and thickness of the linear structure and the coverage area of the linear structure on the layer surface affect the electrical and optical properties of the solar cell, it is necessary to limit the position on both sides of the linear structure, the thickness of the linear structure, and other parameters. The object of the present invention is to provide a method for preparing a linear structure, which can conveniently control and limit the position on the side of the linear structure, the thickness of the linear structure, and other parameters.

[0012] To optimize the power conversion efficiency of a solar cell, a commonly considered method is to increase the transmittance of the front electrode, for example, by reducing its layer thickness and thereby increasing the generated photocurrent. However, this results in an increase in the sheet resistance of the front electrode, thereby increasing the conduction loss. To reduce such conduction loss in the front electrode layer, narrow metal grid lines with high conductivity can be applied on the front electrode layer to improve the relevant conductivity, which is called the metallization process in photovoltaic production. Therefore, as Figure 3 , 4 and as shown in 5, the metal grid lines G1 are applied transversely to the cell or perpendicular to P1 / P2 / P3 at periodic intervals. These grid lines G1 are continuously applied to the solar cell. The gate line G1 is interrupted by P3 to prevent a short circuit between the front electrode of one cell and its adjacent cell.

[0013] As Figure 6 shown, in the case of a monolithic interconnected cell, the current flowing to the end of the cell collected by the metal grid line G1 is directly connected to the back electrode of the next cell through the P2 line. The metal grid line G1 reduces the conduction loss caused by the thinning of the front electrode, thereby offsetting the increase in the series resistance. However, due to the shadow caused by the opaque metal grid lines, this also results in an increase in the dead zone.

[0014] The light-shielding area of the lower absorption layer is defined by the width and length of the metal grid line G1. Although considering the beneficial effect of carrier collection in the metal grid line and the thinner front electrode (increasing the photocurrent without increasing the series resistance), the length of the metal grid line G1 should not be changed, but the width and thickness of the metal grid line G2 can be optimized to reduce the light-shielding area, thereby increasing the photocurrent and the efficiency of the solar cell. The relationship between the thickness and width of the metal grid line G1 is called the aspect ratio. The series resistance of the metal grid line G1 is determined by the specific series resistance and the cross-sectional area of the material it is composed of. Therefore, to improve the efficiency of the solar cell, the light shielding should be reduced by reducing the width of the metal grid line G1, and the thickness of the metal grid line G2 should be increased to prevent conduction loss. Generally speaking, the purpose of using the metal grid line G1 is to apply a line with the smallest width and sufficient thickness to reduce the shielding of the metal grid line G2 and ensure a low series resistance, while increasing the generated photocurrent and the efficiency of the solar cell.

[0015] As Figure 6 shown, in the case of a monolithic interconnected cell, the current is collected on the metal grid lines at the end of the cell and needs to be evenly distributed at the start of the next cell. Otherwise, further conduction losses will occur at the front and rear electrodes. Therefore, additional metal grid lines G2 can be used in the dead zone. As Figure 14 and Figure 15 shown, the metal grid lines G2 are perpendicular to the metal grid lines G1 and are deposited just on or parallel to the P2 structure lines. The purpose of applying G2 is to evenly distribute the current and reduce the electrical losses along the P2 interconnection between two adjacent cells, as Figure 16 and 17 shown, which is caused by the high current collection of the G1 metal grid lines and their timely connection to P2. Since G2 is arranged in the dead zone, no additional light loss will be caused by shadowing. In addition, it can improve the generation of photocurrent by reflecting light from the grid lines G2 to the back of the cover layer / front glass, and then it can further enter the absorption layer.

[0016] Therefore, in order to precisely manage the electricity and optics in the dead zone, it is necessary to precisely deposit the line G2. In addition, when G2 is deposited at the edges of the P1 and P3 lines, it may cause shunting in the active cell area. In addition, the line G2 is mechanically torn by the mechanical scribing of the P3 patterned line, or the area proposed for the laser P3 line is masked, resulting in discontinuous P3 lines and thus shunting. Generally speaking, it is very important to truly confine the line G2 within the boundaries of the P2 patterned lines. Otherwise, if G2 is significantly wider than P2, it will increase the dead zone.

[0017] In addition, in the prior art, the process method for manufacturing metal grids, such as the ALD (aluminum wire deposition) proposed by Solibro, is a method of depositing an aluminum wire structure through a combination of thermal evaporation and masks. The resulting structure is as Figure 7 shown. The various disadvantages of this method are: 1) low throughput and yield due to the use of masks; 2) the high cost of such special masks for producing large-area modules; 3) high material waste caused by evaporation; 4) a large amount of mask maintenance work, which is crucial for the efficiency of solar cells; and 5) limitations on the width (and aspect ratio) of the metal grid lines (the too-narrow mask openings less than a few hundred micrometers are easily blocked during or after use).

[0018] For example, Nice Solar uses screen printing to deposit its metal grid lines. For large-area printing, screen printing is not suitable because of its critical technical limitations. Large printing patterns may result in low deposition accuracy and poor line shape (wider lines), especially in the middle area of printing regions with large sizes (>1 m²), due to the low stiffness (bending) at the center of large screens. In addition, printing narrow lines using screen printing requires high-quality screens, such as hardened and calendered stainless-steel screens or knotless screens. For full-size thin-film solar cell modules (e.g., >1 m²), these high-quality large-size screens are difficult to manufacture (less than two suppliers in the world can do it), and are very expensive. In addition, the screens used in the screen printing process are prone to clogging and difficult to clean. Besides the high cost of screen printing for large thin-film modules, changing the printed pattern of grid lines is quite inflexible when the line spacing needs to be adjusted during the production process.

[0019] Other process methods for manufacturing metal grids, such as aerosol jet printing or dispensing, are new technologies for the metallization process, but still have serious problems with process stability. The nozzles used for aerosol jetting and dispensers are easily clogged by metal particles during long-term printing, resulting in frequent process downtimes. In addition, these two methods can print a maximum of 5 to 10 grid lines simultaneously. For large-area thin-film module printing, multiple prints are required. Currently, the throughput of aerosol jet printing is very low, and it is difficult to further increase the number of nozzles for dispensing or aerosol jetting because the slurry / aerosol distribution along the horizontal direction in the print head is very challenging. Currently, ten nozzles are almost the bottleneck for these two technologies.

[0020] Other process methods for manufacturing metal grids, such as inkjet printing technology, print solvent-based inks or slurries on the surface of the front electrode layer to form metal grid lines. Inkjet printing is suitable for various line shapes and forms because it is a digital printing technology (e.g., PCT / CN2022 / 074345). This also makes it suitable for large-scale applications, especially in the field of thin-film photovoltaics. One of the main drawbacks of this technology is that the composition of the ink contains a small amount of metal particles and a large amount of solvent. This usually results in wide and thin lines on top of the front electrode of the solar cell. In addition, due to the Figure 8 coffee-ring effect as shown, the edges of the ejected ink lines are thicker than the middle of the lines.

[0021] In the prior art, when fabricating metal grid lines on the surface of the front electrode of a solar cell, solvent-based inks or pastes are usually used. The width of the metal grid lines depends to a large extent on the surface tension and wettability of the ink or paste, which greatly limits the use of the material as a front electrode and / or the surface formation and / or surface treatment for optimizing the aspect ratio. In addition, since most metal grid lines must be heated to remove the solvent and improve conductivity, the shape of the lines may change after the deposition of the metal grid lines. Solvent-based inks or pastes are composed of metal and solvent in a certain proportion. In one method, only reducing the ratio of the solvent to the metal (re-formulating) may reduce the width of the lines, but this method easily causes clogging of the print head or screen. In another method, the line width is reduced by using less material (smaller droplets), but this method simultaneously causes the metal grid lines to become thinner, thereby increasing the series resistance. To overcome this problem, multi-application solutions can usually maintain a small line width and increase the thickness of the metal lines. However, especially for high speed in high throughput in mass production, this method shows major drawbacks because the alignment of the production line is crucial and dispersion of the production line also occurs. Summary of the Invention

[0022] In view of the problems existing in the prior art, the present invention provides a method for preparing a small-width linear structure on the upper surface of a stacked target layer and its application. Multiple protrusions are generated on the side surface of the linear structure to form a protrusion line. By using the protrusion line, the lateral position of the linear structure can be restricted, so that the linear structure can be restricted unilaterally or bilaterally. Therefore, when the linear structure is bilaterally constrained, the width, thickness and position of the linear structure can be restricted to achieve the control and optimization of the shape of the linear structure; or when the linear structure is unilaterally restricted, the position of the linear structure can be restricted to prevent the linear structure from blocking part of the underlying layer or the target area. The technical solution of the present invention is as follows:

[0023] In a first aspect, there is provided a method for preparing a small-width linear structure on the upper surface of a target layer of a layer stack, the method being applied in the process of preparing a thin-film photovoltaic module, and the layer stack including at least two layers. The method for preparing the linear structure includes the following steps:

[0024] Obtain preset positions of two side edges of the linear structure on the upper surface of the target layer, denoted as a first side edge position and a second side edge position;

[0025] By generating a plurality of protrusions at intervals along the side edge length direction on at least one of the first side edge position and the second side edge position on the upper surface of the target layer, a protrusion line on at least one side edge position is formed; and

[0026] Apply a liquid-type linear structure material on one side of the protrusion line, and after deposition, a linear structure restricted to one side of the protrusion line is obtained.

[0027] In some embodiments, the method for preparing a linear structure includes:

[0028] When a plurality of protrusions are respectively and spaced along the side length direction at the first side position and the second side position on the upper surface of the target layer to form a first protrusion line and a second protrusion line, a liquid-type linear structure material is applied between the first protrusion line and the second protrusion line, and after deposition, a linear structure restricted between the first protrusion line and the second protrusion line is obtained, that is, a bilaterally restricted linear structure; or

[0029] When a plurality of protrusions are respectively and spaced along the side length direction at one side position of the restricted position among the first side position and the second side position on the upper surface of the target layer to form a third protrusion line, a liquid-type linear structure material is applied on one side of the third protrusion line, and after deposition, a linear structure restricted to one side of the third protrusion line is obtained.

[0030] In some embodiments, the interval between two adjacent protrusions on the same protrusion line is small enough to prevent the linear structure material from overflowing from one side of the protrusion line to the other side during deposition.

[0031] In some embodiments, the interval between two adjacent protrusions on the same protrusion line is less than 10 microns.

[0032] In some embodiments, when bilaterally restricting the linear structure, the protrusions of the first protrusion line and the protrusions of the second protrusion line are asymmetric along the center line of the first protrusion line and the second protrusion line.

[0033] In some embodiments, when bilaterally restricting the linear structure, the protrusions of the first protrusion line and the protrusions of the second protrusion line are symmetric along the center line of the first protrusion line and the second protrusion line.

[0034] In some embodiments, the interval between two adjacent protrusions on the same protrusion line is consistent.

[0035] In some embodiments, the interval between two adjacent protrusions on the same protrusion line is inconsistent.

[0036] In some embodiments, the height of the protrusion is large enough to prevent the material for forming the linear structure from overflowing the protrusion during the generation of the linear structure.

[0037] In some embodiments, the height of the protrusion is determined based on the performance parameters of the material for generating the linear structure.

[0038] In some embodiments, the performance parameters of the material for forming the linear structure must be correctly selected, including the dosage, viscosity, and surface tension of the material.

[0039] In some embodiments, the height of the protrusion is greater than 100 nanometers.

[0040] In some embodiments, the method for generating a protrusion includes: applying a pulsed laser that satisfies preset process parameters to the upper surface of a target layer, such that the pulsed laser emits from above the target layer and passes through the target layer to reach the interface between two adjacent layers among multiple layers below the target layer, causing local melting and evaporation of the layer material at the interface between the two adjacent layers to form an upward protrusion.

[0041] In some embodiments, the preset process parameters of the pulsed laser satisfy the following conditions: the wavelength of the pulsed laser is greater than the optical bandgap of the target layer but less than the optical bandgap of at least one layer among the multiple layers below the target layer.

[0042] In some embodiments, among the preset process parameters of the pulsed laser, the laser power of the pulsed laser is determined based on the thickness of the target layer and the performance parameters of the target layer material.

[0043] In some embodiments, the performance parameters of the target layer material at least include the hardness, stiffness, tension, and adhesion of the front electrode layer material.

[0044] In some embodiments, the method for applying a liquid-type linear structure material includes, but is not limited to, inkjet printing, aerosol jetting, screen printing, and dispensing methods.

[0045] In a second aspect, there is provided an application of the preparation method of the linear structure, including: applying to the single-pass application and / or multi-pass application of a liquid linear structure material.

[0046] In a third aspect, based on the above-mentioned preparation method of the linear structure, there is provided a preparation method of a metal grid line based on improving the surface structure of a front electrode, wherein the target layer is a front electrode layer, the multiple layers below the target layer include a buffer / i layer, an absorption layer, a back electrode layer, and a substrate, and the linear structure is composed of metal grid lines located on the upper surface of the front electrode layer.

[0047] In some embodiments, the metal grid lines include metal grid line G1 perpendicular to lines P1, P2, and P3, and metal grid line G2 parallel to line P2 and located above line P2.

[0048] In some embodiments, the method for preparing metal grid line G1 includes:

[0049] G1(1) Obtain the preset positions on the front electrode surface on both sides of metal grid line G1, respectively denoted as the first side preset position and the second side preset position;

[0050] G1(2) Generate a plurality of protrusions at intervals along the side length direction at the first side preset position and the second side preset position respectively to form a first protrusion line and a second protrusion line;

[0051] G1(3) deposits a liquid-type metal grid line material between the first raised line and the second raised line to obtain a metal grid line G1 restricted between the first raised line and the second raised line;

[0052] The method for preparing the metal grid line G2 includes:

[0053] G2(1) obtains the position on the side of the P2 line near the P3 line on the front electrode surface, and this position is denoted as the third side position;

[0054] G2(2) generates a plurality of protrusions at intervals along the side length direction at the third side position to form a third raised line;

[0055] G2(3) deposits a liquid-type metal grid line material within the P2 line to obtain a metal grid line G2, and one side of the metal grid line G2 near the P3 line is restricted by the third raised line.

[0056] In some embodiments, the material of the metal grid line includes but is not limited to metal ink and dielectric ink.

[0057] In a fourth aspect, based on the above method for preparing the metal grid line, a method for optimizing the aspect ratio of the metal grid line based on the improved front electrode surface structure is provided, including: controlling the distance between the first raised line and the second raised line, the height of the protrusions, and the amount of the metal grid line material, and controlling the width and thickness of the metal grid line deposition to control and optimize the aspect ratio of the metal grid.

[0058] In a fifth aspect, based on the method for preparing the metal grid line, a method for preparing a thin-film solar cell is provided, including the following steps:

[0059] Sequentially fabricating the substrate, rear electrode layer, absorption layer, buffer / i layer, and front electrode layer of the thin-film solar cell, or sequentially fabricating the substrate, front electrode layer, buffer / i layer, absorption film, and rear electrode layer of the film solar cell;

[0060] After fabricating the rear electrode layer, arrange the P1 line on the rear electrode layer; after forming the buffer / i layer, arrange the P2 line on the absorption layer and the buffer / i film; after forming the front electrode layer, arrange the P3 line on the front electrode layer; divide and connect in series the large-area thin-film solar cell through the P1 line, P2 line, and P3 line; and

[0061] Based on the above method for preparing the metal grid line, form the metal grid line G1 and the metal grid line G2 respectively on the surface of the front electrode layer far from the buffer layer. Description of the Drawings

[0062] Figure 1 is a schematic cross-sectional view of a thin-film solar cell;

[0063] Figure 2 It is a schematic diagram of the cell width, active region and dead region of a thin-film solar cell;

[0064] Figure 3 It is a schematic cross-sectional view of a thin-film solar cell with a metal gate line G1;

[0065] Figure 4 It is a schematic diagram of the gate width and gate pitch of a thin-film solar cell with a metal gate line G1;

[0066] Figure 5 It is a top view of three interconnected cells of a thin-film photovoltaic module with a metal grid line G1;

[0067] Figure 6 It is a schematic diagram of the current direction flowing into the metal gate line G1;

[0068] Figure 7 It is a schematic diagram of a grid deposition process on a substrate using thermal evaporation and a mask;

[0069] Figure 8 It is the "coffee ring" effect produced by inkjet printing technology;

[0070] Figure 9 It is a schematic diagram of forming protrusions by using a pulsed laser during the preparation of the metal grid line G1;

[0071] Figure 10 It is a grayscale image taken by a confocal microscope when two protrusion lines are formed on the top of the front electrode during the preparation of the metal grid line G1, where Figure 10 (a) is a 2D image, Figure 10 (b) is a 3D image;

[0072] Figure 11 It is a cross-sectional image of two protrusion lines formed on the top of the front electrode during the preparation of the metal grid line G1;

[0073] Figure 12 It is a schematic diagram of the constraint effect of two pairs of protrusions with liquid metal grid line material inside on the first and second protrusion lines;

[0074] Figure 13 It is a schematic diagram of the possible position distribution of the protrusions on the first and second protrusion lines;

[0075] Figure 14 It is a cross-sectional view of the layer stack of a thin-film solar cell with two metal grid lines G1 and G2;

[0076] Figure 15is a top view of a thin-film solar cell having two metal gate lines G1 and G2;

[0077] Figure 16 is a top view of three interconnected cells of a thin-film photovoltaic module having two metal grid lines G1 and G2;

[0078] Figure 17 is a schematic diagram of the current directions at two metal grid lines G1 and G2;

[0079] Figure 18 is a schematic diagram of the protrusions for generating a third raised line using a pulsed laser;

[0080] Figure 19 is a pseudo 3D grayscale image of the third raised line taken by a confocal microscope, where Figure 19 (a) is a pseudo 3D grayscale image of the third raised line that can unidirectionally restrict the metal grid line G2, Figure 19 (b) is a pseudo 3D grayscale image of the grooves caused by ablation of the buffer layer and the front electrode due to applying too high a laser power during the formation of the above-mentioned protrusions;

[0081] Figure 20 is a pseudo 2D grayscale image of the third raised line;

[0082] Figure 21 is a cross-sectional image of the protrusions of the third raised line;

[0083] Figure 22 is a schematic diagram of depositing the material of the metal grid line G2 on the P2 line after forming the third raised line, where Figure 22 (a) is a schematic diagram of applying the material of the metal grid line G1 on the P2 line after forming the second raised line;

[0084] Figure 23 is a schematic diagram of the position distribution of the protrusions on the third raised line.

[0085] Reference numerals: 1. Front electrode layer; 2. Buffer layer; 3. Absorption layer; 4. Back electrode layer; 5. Substrate; 6. Metal grid line G1. Detailed implementation manners

[0086] The present invention is applied to a method for preparing a thin-film photovoltaic module, which is composed of a stack. For example, the thin-film photovoltaic module sequentially includes a substrate, a back electrode layer, an absorption layer, a buffer / i layer, and a front electrode layer from bottom to top. When a small-width linear structure (such as a metal grid line) needs to be prepared on the upper surface of a layer during the process of preparing the thin-film photovoltaic module, considering the need to control and limit the width, thickness, and position of the small-width linear structure, the present application provides a method for having a small-width linear structure on the upper surface of a target layer in a layer stack. This method is applied to the process of preparing a thin-film optoelectronic module, and the layer stack includes at least two layers. The method for preparing the linear structure includes the following steps:

[0087] Obtain the preset positions of the two side edges of the linear structure on the upper surface of the target layer, denoted as the first side edge position and the second side edge position;

[0088] Form a raised line at at least one of the first side edge position and the second side edge position on the upper surface of the target layer by generating a plurality of protrusions at intervals along the side edge length direction; and

[0089] Apply a liquid-type linear structure material on one side of the raised line, and obtain a linear structure restricted to one side of the raised line through deposition.

[0090] In an embodiment of the present application, a plurality of protrusions are generated on the side edge of the linear structure to form a raised line, and the side position of the linear structure is restricted by the raised line. It can be understood that if the first raised line is formed at the first side position, when the liquid-type linear structure material is applied to the side of the first raised line close to the second side position, the first side of the linear structure obtained through deposition is restricted to the area of the first raised line close to the second side position, and the first side of the linear structure obtained through deposition will not reach the area of the first raised line far from the second side, that is, the raised line restricts the side position of the deposited liquid-type linear structure material. It can be understood that when the first raised line and the second raised line are respectively formed at the first side position and the second side position, a linear structure with both side positions restricted can be obtained by applying the liquid-type linear structure material between the first raised line and the second raised line, that is, a linear structure restricted between the first raised line and the second raised line can be obtained through deposition. When a raised line (denoted as the third raised line) is formed at one of the first side position and the second side position, the liquid-type linear structure material is applied to one side of the third raised line, and one side of the linear structure obtained through deposition is restricted to one side of the third raised line and will not reach the other side of the third raised line.

[0091] In addition, when a plurality of protrusions are generated at intervals along the side length direction at the first side position and the second side position on the upper surface of the target layer to form a first protrusion line and a second protrusion line, a liquid-type linear structure material is applied between the first protrusion line and the second protrusion line, and after deposition, a linear structure restricted between the first protrusion line and the second protrusion line is obtained, that is, a bilaterally restricted linear structure; or

[0092] When a plurality of protrusions are generated at intervals along the side length direction at one side position of the restricted position among the first side position and the second side position on the upper surface of the target layer to form a third protrusion line, a liquid-type linear structure material is applied on one side of the third protrusion line, and after deposition, a linear structure restricted on one side of the third protrusion line is obtained.

[0093] In the embodiments of the present application, the linear structure can be restricted bilaterally or unilaterally by a protrusion line formed by a plurality of closely adjacent protrusions.

[0094] It can be understood that according to the method for preparing a small-width linear structure on the upper surface of the target layer in layer stacking, when a liquid-type linear structure material is used to manufacture a linear structure in the large-scale production process of a thin-film solar cell, due to the characteristics that the surface tension, wettability and other properties of the linear structure material and the shape of the line formed by the deposited linear structure material are not easy to control, a plurality of upward protrusions are generated on the upper surface of the target layer of the thin-film solar cell, and the edge of the deposition area of the linear structure material is surrounded by a protrusion line formed by a plurality of densely distributed protrusions to limit the deposition area to achieve the linear control of the linear structure. Then, by adjusting the position of the protrusions, that is, changing the position of the protrusion line, at least one side position of the linear structure can be restricted, and the line width of the linear structure can be changed by restricting the positions on both sides of the linear structure. Of course, if the amount of the linear structure material is fixed, the reduction of the line width of the linear structure will also lead to the increase of the line thickness of the linear structure. Or, if the line width of the linear structure remains unchanged, the line thickness of the linear structure can also be increased by increasing the height of the protrusions, for example, by increasing the amount of the applied linear structure material.

[0095] It can be understood that after a plurality of upward protrusions are generated on the upper surface of the target layer of the thin-film solar cell, if the distance between two adjacent protrusions (protrusion A and protrusion B) is very small, the linear structure material cannot be accommodated between the two adjacent protrusions (protrusion A and protrusion B). Therefore, a plurality of protrusions A and B (the distance between protrusion A and protrusion B is very small) can be connected together to form a protrusion line to prevent the linear structure material from overflowing from the position of the protrusion line, so as to restrict at least one side position of the linear structure.

[0096] If the distance between two adjacent protrusions (Protrusion C and Protrusion D) is large and a "valley" is formed between Protrusion C and Protrusion D, the linear structure material can be accommodated between the two adjacent protrusions (Protrusion C and Protrusion D). On this basis, ensuring that the heights of Protrusion C and Protrusion D are high enough, by adjusting the distance between Protrusion C and D, the width of the linear structure material deposited between Protrusion C and D can be freely controlled. Therefore, the line width of the linear structure can be changed by changing the distance between the protrusions.

[0097] Multiple protrusions A and B (the distance between Protrusion A and Protrusion B is very small) are connected together to form a protrusion line, which can be used to limit the overflow of the metal grid line material from the protrusion line. When multiple protrusion lines are used in combination, the area between adjacent or close protrusion lines can accommodate the linear structure material.

[0098] It can be understood that the linear structure can be a straight line or other shapes, and different-shaped linear structures can be deposited by only adjusting the shape of the protrusion line. In the embodiments of the present application, a straight-line linear structure is taken as an example for illustration.

[0099] Specifically, the method for bilaterally or unilaterally constraining the linear structure in the embodiments of the present application includes the following steps:

[0100] (Step 1) Determine the preset position of the linear structure on the upper surface of the target layer, and in combination with the preset width of the linear structure, determine the preset positions of the two side edges of the linear structure on the upper surface of the target layer, denoted as the first side edge preset position and the second side edge preset position. It can be understood that the preset width is the preferred value that satisfies the width of the linear structure determined before manufacturing the linear structure; therefore, the distance between the first side edge preset position and the second side edge preset position is the preferred width of the linear structure;

[0101] (Step 2) When it is necessary to limit the positions of the two side edges of the linear structure, a plurality of protrusions are generated at intervals along the side edge length direction on the first side edge position and the second side edge position respectively to form a first protrusion line and a second protrusion line; apply the linear structure material between the first protrusion line and the second protrusion line, and the area between the first protrusion line and the second protrusion line is the area where the linear structure is located;

[0102] (Step 3) When it is necessary to limit the position of one side edge of the linear structure, a plurality of protrusions are generated at intervals along the side edge length direction on one side edge position of the restricted position among the first side edge preset position and the second side edge preset position to form a third protrusion line; apply the liquid-type linear structure material on one side of the third protrusion line, and the linear structure restricted to one side of the third protrusion line is obtained after deposition.

[0103] In addition, for the first raised line, the second raised line, and the third raised line in the above steps 1 to 3, the interval between two adjacent protrusions on the same raised line is small enough to prevent the linear structure material from overflowing from one side of the raised line to the other side during the deposition process.

[0104] It can be understood that both the bilateral constraint achieved by the first raised line and the second raised line and the unilateral constraint achieved by the third raised line require that when the linear structure material is applied to one side of the raised line, the linear structure material will not overflow to the other side of the raised line after deposition. Specifically, if the linear structure is restricted on the left and right by the first raised line and the second raised line, and the interval between two adjacent protrusions on the first raised line is small enough, then the interval between these two adjacent protrusions on the second raised line is also small enough to prevent the linear structure material from overflowing the area between the first raised line and the second raised line during the deposition process. If the linear structure is unilaterally restricted by the third raised line, then the interval between two adjacent protrusions on the third raised line is small enough to prevent the linear structure material from overflowing from one side of the third raised line to the other side of the third raised line during the deposition process.

[0105] In another embodiment, the interval between two adjacent protrusions on the same raised line is less than 10 microns. That is to say, the interval between two adjacent protrusions on the first raised line is less than 10 microns, and the interval between these two adjacent protrusions on the second raised line is also less than 10 microns. In some embodiments, the interval between two adjacent protrusions on the same raised line is a few microns.

[0106] In one embodiment, when the linear structure is bilaterally restricted, the protrusions of the first raised line and the protrusions of the second raised line are asymmetric along the center line between the first raised line and the second raised line.

[0107] In another embodiment, when the linear structure is bilaterally restricted, the protrusions of the first raised line and the protrusions of the second raised line are symmetric along the center line between the first raised line and the second raised line.

[0108] Specifically, referring to Figure 13 , when the linear structure is bilaterally restricted, in one embodiment, the distribution intervals between the protrusions of the first raised line correspond to the distribution intervals of the second raised line, that is, the distribution intervals between the protrusions of the first raised line are related to the distribution intervals of the protrusions on the second raised line. In another embodiment, the distribution intervals between the protrusions of the first raised line may not correspond to the distribution intervals of the second raised line, that is to say, the distribution intervals between the protrusions on the first raised line are not related to the distribution intervals of the protrusions on the second raised line. There is a center line between the first raised line and the second raised line, and a protrusion on the first raised line and a protrusion on the second raised line can be symmetric about the center line (as Figure 13(as shown in (a)). Of course, one protrusion on the first protrusion line and another protrusion on the second protrusion line can be asymmetric about the center line (as shown in Figure 13 (b) and 13(c)).

[0109] In addition, in one embodiment, the intervals between two adjacent protrusions on the same protrusion line are consistent. That is to say, when the linear structure is bilaterally restricted, the intervals between two adjacent protrusions on the first protrusion line are consistent and / or the intervals between two adjacent protrusions on the second protrusion line are consistent (as shown in Figure 13 (a) and Figure 13 (b)). When the linear structure is unilaterally restricted, the intervals between two adjacent protrusions on the third protrusion line are consistent, as shown in Figure 23 (a).

[0110] In another embodiment, the intervals between two adjacent protrusions on the same protrusion line are inconsistent. That is to say, when the linear structure is bilaterally restricted, the intervals between two adjacent protrusions on the first protrusion line are inconsistent and / or the intervals between two adjacent protrusions on the second protrusion line are inconsistent (as shown in Figure 13 (c)). When the linear structure is unilaterally restricted, the intervals between two adjacent protrusions on the third protrusion line are inconsistent, as shown in Figure 23 (b).

[0111] In short, the distribution intervals between the protrusions on different protrusion lines have no influence on each other, as long as the intervals between two adjacent protrusions on the same protrusion line are small enough to prevent the linear structure material from overflowing from one side of the protrusion line to the other side during the deposition process.

[0112] In order to prevent the linear structure material from overflowing from one side of the protrusion line to the other side during the deposition process, that is, in order to prevent the linear structure material from overflowing from one side of the protrusion to the other side during the deposition process. There are also requirements for the height of the protrusion. In one embodiment, the height of the protrusion needs to be large enough to prevent the material used to form the linear structure from overflowing the protrusion during the formation of the linear structure. In another embodiment, the required height of the protrusion is determined based on the characteristic parameters of the linear structure material. For example, the required height of the protrusion is determined according to the amount, viscosity and surface tension of the linear structure material to prevent the linear structure material from overflowing the protrusion. In another embodiment, the height of the protrusion needs to be greater than 100 nanometers. Generally speaking, the height of the formed protrusion is usually in the range of several hundred nanometers to micrometers.

[0113] Next, the method for manufacturing the protrusion will be described.

[0114] For the method of generating protrusions on the first protrusion line, the second protrusion line, and the third protrusion line, it includes: applying pulsed laser satisfying preset process parameters on the upper surface of the target layer, such that the pulsed laser emits from above the target layer and passes through the target layer to reach the interface between two adjacent layers among multiple layers below the target layer, generating local melting and evaporation of the layer material at the interface between the adjacent two layers, and forming an upward protrusion.

[0115] As Figure 9 and Figure 18 shown, the pulsed laser is applied to the upper surface of the target layer, allowing it to pass through the target layer and reach the interface between two layers among multiple layers below the target layer, thereby generating local melting and evaporation of the layer material at the interface between the adjacent two layers, forming an upward protrusion, and thus achieving the formation of protrusions on the upper surface of the target layer.

[0116] It should be noted that the preset process parameters of the pulsed laser need to be reasonably set, including the wavelength, power, application time, application frequency, speed, and beam diameter of the pulsed laser. Below, the adjustment of the wavelength and power of the pulsed laser will be taken as an example for illustration.

[0117] The wavelength of the pulsed laser is greater than the optical bandgap of the target layer and less than the optical bandgap of at least one layer of material among multiple layers below the target layer. Therefore, the pulsed laser can pass through the target layer and stop at any layer below the target layer. The pulsed laser will not be absorbed by the layers it passes through, but will be absorbed at the interface where it stops, causing partial melting and evaporation of the material at the interface and forming an upward protrusion.

[0118] Regarding the power of the pulsed laser, it is necessary to adjust the energy of the pulsed laser with the aim of forming an upward protrusion on the upper surface of the target layer. When the power of the pulsed laser is too low, it will only cause local heating and no protrusion can be formed. Excessive power will cause the layers passed through by the pulsed laser to be completely ablated, forming holes instead of upward protrusions.

[0119] Specifically, the laser power of the pulsed laser is adjusted according to the thickness of the target layer and the performance parameters of the target layer material. For example, the laser power of the pulsed laser is determined according to performance parameters such as the hardness, stiffness, tension, and adhesion of the front electrode layer material.

[0120] In the present invention, the method for applying liquid-type linear structure materials includes but is not limited to inkjet printing, aerosol jetting, screen printing, and dispensing methods.

[0121] The present invention provides a method for preparing a small-width linear structure on the upper surface of a target layer in a layer stack, and this method is applied to the preparation process of thin-film photovoltaic modules. This method can be used for the preparation of thin-film photovoltaic modules with substrate and superstrate structures, and can be applied to the preparation of thin-film photovoltaic modules of CIGS, CdTe, and perovskite types.

[0122] The method for preparing a small-width linear structure on the upper surface of the target layer of the layer stack according to the present invention can also be applied to the single-pass application and / or multi-pass application of the liquid linear structure material.

[0123] The following will be described by taking a linear structure composed of metal grid lines as an example. In the present invention, it is necessary to fabricate the metal grid line G1. In order to control and optimize the shape (including width and thickness parameters) of the metal grid line G1 on the front electrode surface to achieve the optimization of the aspect ratio of the metal grid line G1, it is necessary to first generate two raised lines at two side positions of the metal grid line G1 on the front electrode surface, and accommodate the metal grid line material in the regions on the two raised lines for deposition, thereby forming the metal grid line G1. Since it is necessary to fabricate the metal grid line G2 in the present invention, in order to control that the side of the metal grid line G2 close to the P3 line does not cover the P3 line or is cut by the P3 line, it is necessary to generate one third raised line on the side of the P2 line close to the P3 line on the front electrode surface, so that the side of the metal grid line G2 close to the P3 line will not overflow the third raised line after the deposition of the metal grid line G2 material, and the position of the side of the metal grid line G2 close to the P3 line is restricted from reaching the P3 line.

[0124] Specifically, based on the method for preparing a small-width linear structure on the upper surface of the target layer of the layer stack, a method for preparing metal grid lines based on the improved surface structure of the front electrode is provided. The target layer is the front electrode layer, and the multiple layers under the target layer include a buffer / i layer, an absorption layer, a back electrode layer, and a substrate. The linear structure is composed of metal grid lines located on the upper surface of the front electrode layer. The metal grid lines include the metal grid line G1 perpendicular to the P1 line, P2 line, and P3 line, and the metal grid line G2 parallel to the P2 line and located above the P2 line. It can be understood that in the embodiments of the present application, it is necessary to control and optimize the width and thickness of the metal grid line G1 to optimize the aspect ratio of the metal grid line G1, that is, it is necessary to restrict the two side positions of the metal grid line G1. In the embodiments of the present application, it is necessary to restrict the unilateral position of the metal grid line G2 to prevent the side of the metal grid line G2 close to the P3 line from reaching the P3 line, that is, from covering the P3 line or being cut by the P3 line. Specifically, the method for preparing the metal grid line G1 includes:

[0125] G1(1) Obtain the preset positions on the front electrode surface on both sides of the metal grid line G1, which are respectively represented as the first side preset position and the second side preset position;

[0126] G1(2) Generate a plurality of protrusions at intervals along the side length direction at the first side preset position and the second side preset position respectively to form a first raised line and a second raised line;

[0127] G1(3) deposits a liquid-type metal grid line material between the first raised line and the second raised line to obtain a metal grid line G1 restricted between the first raised line and the second raised line;

[0128] The method for preparing the metal grid line G2 includes:

[0129] G2(1) obtains the position of the side of the P2 line near the P3 line on the front electrode surface, and this position is denoted as the third side position;

[0130] G2(2) generates a plurality of raised portions at intervals along the side length direction at the third side position to form a third raised line;

[0131] G2(3) deposits a liquid-type metal grid line material within the P2 line to obtain a metal grid line G2, and one side of the metal grid line G2 near the P3 line is restricted by the third raised line.

[0132] It can be understood that the width and thickness of the metal grid line G1 are controlled by the above steps G1(1), G1(2), and G1(3). Specifically, in step G1(1), the preset position of the metal grid line G1 on the front electrode surface is determined, and in combination with the preset width of the metal grid line G1, the preset positions of both sides of the metal grid line G1 on the front electrode are determined. Denote them as the first side preset position and the second side preset position. It can be understood that the preset width is the preferred value of the metal grid line width that satisfies the aspect ratio condition of the metal grid line before manufacturing the metal grid line; therefore, the distance between the first side preset position and the second side preset position is the preferred width of the metal grid line. In step G1(3), the method of applying the metal grid line material can be inkjet printing, aerosol jetting, screen printing, dispensing method, etc., and inkjet printing is the preferred technology.

[0133] During the process of fabricating the metal grid lines G1 and G2, the method of generating protrusions is as follows: Pulse laser satisfying preset process parameters is applied to the surface of the front electrode layer away from the buffer layer, such that at least the front electrode layer bulges upward at the laser application position. Specifically, in the present invention, the pulse laser is applied to the surface of the front electrode layer, such that the pulse laser passes through the front electrode layer from above the thin-film solar cell until one of the lower layers, i.e., the buffer / i layer, the absorption layer, the back electrode layer, and the substrate absorbs the laser radiation, and when the pulse laser attempts to pass through the interface where it stops, melting and evaporation of some layer materials will occur, thereby forming an upward protrusion at the position where the pulse laser is applied. The preset process parameters of the pulse laser need to be reasonably set, including the wavelength, power, application time, application frequency, speed, and beam diameter of the pulse laser. For example, in the embodiments of the present application, the wavelength of the pulse laser applied to the upper surface of the front electrode layer needs to be greater than the optical bandgap of the front electrode layer, so that the pulse laser can pass through the front electrode layer, while the wavelength of the pulse laser is less than the optical bandgap of at least one of the buffer / i layer, the absorption layer, and the back electrode layer. For example, if the wavelength of the pulse laser is greater than the optical bandgaps of the front electrode layer and the buffer / i layer and less than the optical bandgap of the absorption layer, the laser passes through the front electrode layer and the buffer / i, and is absorbed when reaching the interface between the buffer layer and the absorption layer, resulting in melting and evaporation of some materials at the interface between the absorption layer and the buffer / i layer, resulting in an upward protrusion along the front electrode direction in the layer stack.

[0134] Regarding the power of the pulse laser, it is necessary to determine the energy of the pulse laser for the purpose of forming an upward protrusion on the surface of the front electrode layer. When the power of the pulse laser is too low, only local heating will be caused and no protrusion can be formed. Excessive power will cause complete ablation of the buffer / i layer and the front electrode layer, just as it is used for scribing the laser P3 line, which will cause the line to become wider and the series resistance to increase because the interconnect area between the metal grid line and the front electrode is greatly reduced (reaching the thickness of the front electrode layer). Specifically, the laser power of the pulse laser is determined according to the thickness of the front electrode layer and the performance parameters of the front electrode layer material. For example, the laser power of the pulse laser is determined according to the performance parameters such as the hardness, stiffness, tension, and adhesion of the front electrode layer material.

[0135] For example, during the process of fabricating the metal grid lines G1 and G2, the process parameters of the pulse laser used for forming protrusions may be as follows: For CIGS with an AZO (front electrode) thickness of 750 nm and a ZnOS (buffer layer) thickness of 65 nm, the laser power window is between 150 mW and 250 mW, the wavelength is 1064 nm, the laser pulse width is 15 ps, the repetition frequency is 500 kHz, the processing speed is 10800 mm / min, and the beam diameter is approximately 20 μm.

[0136] Figure 10Shows a microscopic image of the first raised line and the second raised line (the distance between the first raised line and the second raised line is 20 micrometers) during the preparation of the metal grid line G1. Figure 11 Shows a cross-sectional image of the first raised line and the second raised line (the distance between the first raised line and the second raised line is 10 micrometers). Since the width of a single protrusion on the first raised line and the second raised line is in the range of about 10 micrometers, the distance between the first raised line and the second raised line should be greater than 10 micrometers so that the material of the metal grid line G1 can be accommodated between the first raised line and the second raised line, thereby forming the metal grid line G1 between the first raised lines.

[0137] Refer to Figure 12 , when the material of the metal grid line G1 is restricted between two protrusions, the material of the metal grid line G1 is filled in the space between the two protrusions, and the coffee ring effect as shown in Figure 8 is also avoided.

[0138] Figure 18 Shows a schematic diagram of the protrusions of the third raised line generated by using a pulsed laser during the preparation of the metal grid line G2. Figure 19 Shows a pseudo-3D grayscale image of the third raised line during the preparation of the metal grid line G2, where Figure 19 (a) shows a pseudo-3D grayscale image of the unilateral restriction of the metal grid line G1 on the formed third raised line, Figure 19 (b) is a pseudo-3D grayscale image showing the case where the buffer / i layer and the front electrode will be ablated to generate a groove when the laser power is too high. Figure 20 Shows a pseudo-2D grayscale image of the third raised line for achieving unilateral restriction, Figure 21 Is a cross-sectional image of the protruding part of the third raised line, showing the maximum height, average height and width of the protruding part of the third raised line. Figure 22 Shows a schematic diagram of depositing the material of the metal grid line G2 on the P2 line after forming the third raised line, where Figure 22 (a) shows the schematic diagram of applying the material of the metal grid line G2 on the P2 line after forming the third raised line, Figure 22 (b) shows the schematic diagram of the side close to P3 being restricted after depositing the material of the metal grid line G2.

[0139] It should be noted that the material of the metal grid line includes but is not limited to metal ink and dielectric ink.

[0140] Based on the above method for preparing metal grid lines based on the improved front electrode surface structure, the present invention also provides a method for optimizing the aspect ratio of metal grid lines, including: controlling the width and thickness of the deposited metal grid lines by controlling the distance between the first raised line and the second raised line, the height of the protrusions, and the amount of the metal grid line material, so as to control and optimize the aspect ratio of the metal grid.

[0141] Based on the above method for preparing metal grid lines based on the improved front electrode surface structure, a method for preparing a thin film solar cell is provided, including the following steps:

[0142] Manufacturing process of the photovoltaic module: When preparing the photovoltaic module using the substrate method, the substrate, back electrode layer, absorption layer, buffer / i layer, and front electrode layer of the thin film solar cell are sequentially fabricated; when preparing the photovoltaic module using the superstrate structure method, the substrate, front electrode layer, buffer / i layer, absorption layer, and back electrode layer of the thin film solar cell are sequentially fabricated; this process includes producing P1 line, P2 line, and P3 line. After fabricating the back electrode layer, the P1 line is arranged on the back electrode layer; after forming the absorption layer and the buffer / i layer, the P2 line is arranged on the absorption layer and the buffer / i layer; after forming the front electrode layer, the P3 line is arranged on the front electrode layer; thus, the large-area thin film solar cell is divided and connected in series through the P1 line, P2 line, and P3 line; and

[0143] Manufacturing process of the metal grid lines G1 and G2: Based on the above method for preparing metal grid lines, the metal grid line G1 and the metal grid line G2 are respectively prepared on the surface of the front electrode layer far from the buffer layer.

[0144] The present invention is not limited to the above specific embodiments. All kinds of transformations made by those of ordinary skill in the art starting from the above concepts without creative labor fall within the protection scope of the present invention.

Claims

1. A method for preparing a small-width linear structure on the upper surface of a target layer of a stacked structure, which is applied to the preparation process of a thin-film photovoltaic module. The stacked structure includes at least two layers. The method for preparing the linear structure includes the following steps: Obtain the preset positions of the two side edges of the linear structure on the upper surface of the target layer, denoted as the first side edge position and the second side edge position; Form a raised line at at least one of the first side edge position and the second side edge position on the upper surface of the target layer by generating a plurality of protrusions at intervals along the side edge length direction; And Apply a liquid-type linear structure material on one side of the raised line, and obtain a linear structure restricted to one side of the raised line through deposition.

2. The method for preparing a linear structure according to claim 1, wherein When a plurality of protrusions are respectively generated at intervals along the side edge length direction at the first side edge position and the second side edge position on the upper surface of the target layer to form a first raised line and a second raised line, apply a liquid-type linear structure material between the first raised line and the second raised line, and obtain a linear structure restricted between the first raised line and the second raised line through deposition, that is, a bilaterally restricted linear structure; or When a plurality of protrusions are generated at intervals along the side edge length direction at one of the restricted positions of the first side edge position and the second side edge position on the upper surface of the target layer to form a third raised line, apply a liquid-type linear structure material on one side of the third raised line, and obtain a linear structure restricted to one side of the third raised line through deposition.

3. The method for preparing a linear structure according to claim 1, wherein, The interval between two adjacent protrusions on the same raised line is small enough to prevent the linear structure material from overflowing from one side of the raised line to the other side during deposition.

4. The method for preparing a linear structure according to claim 3, wherein, The interval between two adjacent protrusions on the same raised line is less than 10 micrometers.

5. The method for preparing a linear structure according to any one of claims 1 to 4, wherein When restricting the bilateral positions of the linear structure, the protrusions of the first raised line and the protrusions of the second raised line are asymmetric along the center lines of the first raised line and the second raised line.

6. The method for preparing a linear structure according to any one of claims 1 to 4, wherein, When restricting the bilateral positions of the linear structure, the protrusions of the first raised line and the protrusions of the second raised line are symmetric along the center lines of the first raised line and the second raised line.

7. The method for preparing a linear structure according to any one of claims 1 to 4, wherein The intervals between two adjacent protrusions on the same raised line are consistent.

8. The method for preparing a linear structure according to any one of claims 1 to 4, wherein, The intervals between two adjacent protrusions on the same raised line are inconsistent.

9. The method for preparing a linear structure according to claim 1, wherein, The height of the protrusion is large enough to prevent the material used to form the linear structure from overflowing the protrusion during the formation of the linear structure.

10. The method for preparing a linear structure according to claim 9, wherein, The height of the protrusion is determined based on the performance parameters of the material used to form the linear structure.

11. The method for preparing a linear structure according to claim 10, wherein, The performance parameters of the material used to form the linear structure at least include the amount, viscosity, and surface tension of the material.

12. The method for preparing a linear structure according to claim 10, wherein The height of the protrusion is greater than 100 nanometers.

13. The method for preparing a linear structure according to claim 1, wherein, The method for preparing the protrusion includes: applying a pulsed laser that meets preset process parameters on the upper surface of the target layer, so that the pulsed laser emits from above the target layer and passes through the target layer to reach the interface between two adjacent layers in the multi-layers below the target layer, and local melting and evaporation of the layer material occur at the interface between the two adjacent layers to form an upward protrusion.

14. The method for preparing a linear structure according to claim 13, wherein, The preset process parameters of the pulsed laser satisfy the following conditions: the wavelength of the pulsed laser is greater than the optical bandgap of the target layer but less than the optical bandgap of at least one layer under the target layer.

15. The method for preparing a linear structure according to claim 13, wherein, Among the preset process parameters of the pulsed laser, the laser power of the pulsed laser is determined based on the thickness of the target layer and the performance parameters of the target layer material.

16. The method for preparing a linear structure according to claim 15, wherein, The performance parameters of the target layer material at least include the hardness, stiffness, tension, and adhesion of the front electrode layer material.

17. The method for preparing a linear structure according to claim 1, wherein, The method for applying the liquid-type linear structure material includes, but is not limited to, inkjet printing, aerosol jetting, screen printing, and dispensing methods.

18. The application of the method for preparing a linear structure according to any one of claims 1 to 17, including the single-pass application and / or multi-pass application to the liquid linear structure material.

19. A method for preparing metal grid lines based on the surface structure of the electrode before improvement in the method for preparing a linear structure according to any one of claims 1 to 17, wherein, The target layer is the front electrode layer, the multiple layers under the target layer include a buffer / i layer, an absorption layer, a back electrode layer, and a substrate, and the linear structure is composed of metal grid lines located on the upper surface of the front electrode layer.

20. The method for preparing the metal grid line according to claim 19, wherein, The metal grid lines include metal grid line G1 perpendicular to lines P1, P2, and P3, and metal grid G2 parallel to line P2 and located above line P2.

21. The method for preparing a metal grid line according to claim 20, characterized in that The method for preparing metal grid line G1 includes: G1(1) Obtain the preset positions on the front electrode surface on both sides of metal grid line G1, which are respectively represented as the first side preset position and the second side preset position; G1(2) Generate a plurality of protrusions at intervals along the side length direction at the first side preset position and the second side preset position to form a first protrusion line and a second protrusion line; G1(3) Apply a liquid-type metal grid line material between the first protrusion line and the second protrusion line for deposition to obtain metal grid line G1 restricted between the first protrusion line and the second protrusion line; The method for preparing metal grid line G2 includes: G2(1) Obtain the position on the side of line P2 close to line P3 on the front electrode surface, and this position is represented as the third side position; G2(2) Generate a plurality of protrusions at intervals along the side length direction at the third side position to form a third protrusion line; G2(3) Apply a liquid-type metal grid line material inside line P2 for deposition to obtain metal grid line G2, and one side of metal grid line G2 close to line P3 is restricted by the third protrusion line.

22. The method for preparing a metal grid line according to claim 19, wherein the metal grid line material includes, but is not limited to, metal ink and dielectric ink.

23. The method for optimizing the aspect ratio of the metal grid lines in the method for preparing metal grid lines according to any one of claims 19 to 22, comprising: By controlling the distance between the first protrusion line and the second protrusion line, the height of the protrusions, and the amount of the metal grid line material, the width and thickness of the metal grid line deposition are further controlled to control and optimize the aspect ratio of the metal grid.

24. The method for preparing a metal grid line according to any one of claims 19-22 is applied to the method for preparing a thin-film solar cell, including the following steps: Manufacture the substrate, rear electrode layer, absorption layer, buffer / i layer, and front electrode layer of the thin-film solar cell sequentially, or manufacture the substrate, front electrode layer, buffer / i layer, absorption layer, and rear electrode layer of the film solar cell sequentially; after manufacturing the rear electrode layer, arrange the P1 line on the rear electrode layer; after forming the buffer / i layer, arrange the P2 line on the absorption layer and the buffer / i film; after forming the front electrode layer, arrange the P3 line on the front electrode layer; divide and connect in series the large-area thin-film solar cell through the P1 line, P2 line, and P3 line; and Based on the method for preparing the metal grid lines according to any one of claims 19 to 22, respectively manufacture the metal grid line G1 and the metal grid line G2 on the surface of the front electrode layer away from the buffer layer.

25. A thin-film photovoltaic module produced by the method according to claim 24.

26. Use of the thin-film photovoltaic module according to claim 25 as part of a building envelope, in particular as a window, facade, or roof component.

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