Manufacturing method for solar power generation modules

Abstract

The present application discloses a method for optimizing the aspect ratio of a metal grid based on surface modification, the method comprising the steps of obtaining a photovoltaic module including a front electrode, applying laser light onto the front electrode, and forming a protrusion structure on the front electrode by laser induction, wherein at least two rows of protrusion structure groups form a confined space, the width of the applied liquid being limited to the spacing between two adjacent protrusion structure groups, and the thickness of the applied liquid being limited to the height of the formed protrusions. According to the method, the upwardly shaped protrusion structure may be an irregular structure and is formed on the front electrode made of the material of the front electrode by laser induction, such that the applied ink and / or paste is confined between two or more lines.

Description

Technical Field

[0001] This application relates to the technical field of optimizing the aspect ratio of metal gratings, and specifically to a method for optimizing the aspect ratio of metal gratings based on surface modification.

Background Art

[0002] Thin-film photovoltaic modules generally consist of a back electrode, an absorber, a buffer layer / i-layer, and a front electrode. To avoid high series resistance and the associated high current losses, the module is usually designed as a series of monolithic interconnected cells, and the specific structure is shown in FIG. 1.

[0003] Generally, such a sequence of cells is shown in FIG. 2 (a plan view of FIG. 1). In FIG. 2, the front electrode and the back electrode are insulated at P1 and P3, and the front electrode and the back electrode are in electrical contact at P2 for the series connection of two adjacent cells. The structural regions of P1, P2, and P3 are also referred to as the "dead areas" of the solar cell because they do not generate electricity, and the remaining regions are referred to as the active cell areas.

[0004] FIG. 3 shows the monolithic connection of three individual cells where the first cell and the third cell are not in contact.

[0005] To optimize the power conversion efficiency of a solar cell, for example, a method of increasing the transmittance of the front electrode by thinning the thickness of the layer and increasing the generated photocurrent is often considered. However, this increases the sheet resistance of the front electrode, resulting in an increase in conduction losses. To reduce such conduction losses in the front electrode, narrow metal grating lines with high conductivity may be applied on the front electrode layer to improve the related conductivity, which is referred to as the metallization process of photovoltaic power generation.

[0006] As shown in Figure 4, because the grid wire material has low series resistance, applying a metal grid to the front electrode collects charge carriers from the front electrode material, causing a concentrated current to flow to the end of the cell. In the case of a monolithic interconnected cell, the current collected by the metal grid wire and directed toward the end of the cell is directly connected to the back electrode of the next cell via the P2 patterning line. While the above metal grid structure reduces conduction losses in the thinned front electrode and offsets the increase in series resistance, it also leads to an increase in dead area due to shading caused by the opaque grid wire above the active cell area.

[0007] The shading area of ​​the lower absorber material is defined by the width and length of the metal wire. While the length of the metal wire should not be altered to benefit from carrier collection within the wire and the thinning of the front electrode (i.e., to increase photocurrent without increasing series resistance), optimizing the width and thickness of the metal wire can reduce the seeding area, thereby increasing the photocurrent and efficiency of the solar cell. The relationship between the width and thickness of the metal wire is called the aspect ratio.

[0008] The series resistance of a metal wire is determined by the specific series resistance and cross-sectional area of ​​its constituent materials. Therefore, to improve the efficiency of solar cells, the width of the metal wire should be reduced to minimize light shielding, while the thickness of the metal wire should be increased to prevent conduction losses.

[0009] Traditionally, commercial thin-film / CIGS solar power manufacturers and their related research institutions have introduced a method called ALD (i.e., aluminum wire deposition) for depositing a metal lattice structure on the front electrode of CIGS modules. This method involves depositing an aluminum wire structure via a mask using thermal evaporation. The resulting structure is shown in Figure 5 and has several drawbacks, as described below. 1) Low throughput and yield due to the use of masks. 2) The high cost of this special mask for producing large-area modules. 3) High material waste due to evaporation 4) The high workload due to mask maintenance, which is crucial for the efficiency of solar cells. 5) Limitations on the width (and aspect ratio) of the metal grid wires (the openings of the mask are too narrow, smaller than several hundred micrometers, and prone to clogging during or after use).

[0010] Another metallization process involves depositing metal grid lines using a screen printing method. However, screen printing is not suitable for large-area printing due to its significant technical limitations. Specifically, large printing patterns are not suitable for large printing areas (e.g., >1 m²) because of the low rigidity of the central screen over a large area (i.e., bending effect). 2 In the intermediate region of the image, this results in low deposition accuracy and poor line shape (i.e., broad lines). Furthermore, printing narrow lines using screen printing requires a high-quality screen (e.g., a hardened and calendered stainless steel screen or a knotless screen). Full-size thin-film solar cell modules (e.g., >1m) 2 In this case, high-quality large screens are extremely difficult to manufacture, with currently fewer than two suppliers worldwide capable of producing them, and they are very expensive. Furthermore, screens used in the grid printing process are prone to clogging and difficult to clean. Typically, screens for Si-PV6 "X6" are discarded if not cleaned after a certain amount of printing. In addition to the high cost of screen printing for large thin-film modules, there is also a lack of flexibility in changing the grid line printing pattern when it is necessary to adjust the line pitch during sample production.

[0011] In addition to conventional screen printing methods, the prior art also describes an alternative rotary screen printing method for conductive metal grid line deposition. This technique is currently only applicable to Si-PV6 "x6" wafers. For applications to large-area thin-film modules, the problems are similar to those of conventional screen printing. For large printing widths such as 600mm to 1300mm, it is difficult for the selected rotary tube material to maintain sufficient rigidity, significantly impacting deposition accuracy and the associated grid line width.

[0012] Electron beam deposition (EVD) processes are only suitable for the fabrication of metal grid wires on a laboratory scale and are not suitable for mass production; therefore, a full-surface plating process is required. When this method is adopted, it has similar problems and limitations to vapor deposition, mainly resulting in low yield and high cost.

[0013] Other process methods, such as aerosol jet printing or dispensing, are newer technologies for metallization processes and have serious problems with process stability. Nozzles used in aerosol jets or dispensers are prone to clogging with metal particles during long printing processes, causing frequent process downtime. Also, these two methods are in the early stages of development and can only print a maximum of 5-10 grid lines. Multiple printing runs are required for printing within large-area thin-film modules. In other words, the throughput of aerosol jet printing is currently very low, and it is very difficult to further increase the number of nozzles for dispensing or aerosol jetting. Horizontal paste / aerosol distribution within the print head is extremely challenging. Currently, ten-nozzle technology is a bottleneck for these two technologies.

[0014] Inkjet printing is a suitable metallization method for photovoltaic modules, such as thin-film PV, organic PV, or silicon solar cells. Because it is a digital printing technology, inkjet printing allows for a wide range of line shapes and forms, making it suitable for large-scale applications, particularly thin-film photovoltaic systems. One major drawback of this technology is that the ink composition contains a small amount of metal particles and a large amount of solvent. This results in the formation of thin lines over a wide area on the top of the front electrodes of the solar cell. Furthermore, due to the coffee ring effect, as shown in Figure 6, the edges of the ejected ink lines become thicker than the center of the line.

[0015] Conventional methods for creating metal grid lines on the front electrodes of solar cells all utilize a common solvent-based ink or paste. These are created according to the actual application process and vary in the ratio of metal to solvent. The width of the metal grid line depends heavily on the surface energy and the wettability of the ink. This clearly limits the use of materials as front electrodes and / or surface formation and / or surface treatment to obtain the optimal aspect ratio. Furthermore, the shape of the coated lines can change after deposition because the metal grid line needs to be heated to remove the solvent and improve conductivity. Simply reducing the solvent-to-metal ratio, i.e., changing the composition, can reduce the line width, but this inevitably causes clogging of the print head or grid, respectively. Another possible method to reduce line width by using less material or smaller droplets can also thin the lines and increase series resistance. To overcome this problem, multi-coating solutions typically maintain a small line width while increasing the thickness of the metal grid line. However, especially in high-throughput, high-speed mass production, this method has a major drawback: the manufactured metal wires undergo scattering, meaning the positions of the generated metal grid wires shift.

[0016] Therefore, to solve the above problem, we provide a method for optimizing the aspect ratio of a metal lattice based on surface modification. [Overview of the Initiative] [Problems that the invention aims to solve]

[0017] In view of the problems present in the prior art described above, this application provides a method for optimizing the aspect ratio of a metal grid based on surface modification. This optimization method aims to reduce shading of metal wires and ensure low series resistance by applying metal grid wires having the minimum width and sufficient thickness. The object of this disclosure is to optimize the aspect ratio by modifying the surface of the front electrode. [Means for solving the problem]

[0018] To achieve the above object, the method for optimizing the aspect ratio of a metal grid based on surface modification adopted in the present application is as follows: obtaining a solar power generation module including a front electrode; providing laser light onto the front electrode; forming a protrusion structure on the front electrode by laser induction, wherein at least two rows of protrusion structure groups form a restricted space, the width of the liquid to be applied is restricted within the interval between two adjacent protrusion structure groups, and the thickness of the liquid to be applied is restricted within the height of the formed protrusions and the surface tension of the liquid.

[0019] Specifically, according to the method of the present application, the upwardly formed protrusion structure may be an irregular structure, and is formed by induction on the front electrode made of the material of the front electrode so that the ink and / or paste to be applied is restricted between two or more lines.

[0020] Specifically, the formed protrusion structure usually has an irregular shape with a height ranging from several hundred nanometers to nanometers, mainly depending on the thickness of the buffer layer and the front electrode. Some protrusions may have small cracks indicating depletion of the evaporation material. Their widths are in the range of several hundred nanometers.

[0021] Specifically, the width of the formed protrusions is in the range of 10 μm, and as a result, the minimum distance between two lines is about 10 μm.

[0022] Furthermore, the method for optimizing the aspect ratio of a metal grid based on the above-mentioned surface modification is applicable to various coating methods such as inkjet printing, including single-pass technology and aerosol jet, screen printing, dispensing, etc.

[0023] Specifically, the present application helps to prevent the expansion of line width due to small misalignments in the high-speed alignment of ink coating in mass production.

[0024] The method for optimizing the aspect ratio of the metal grid based on the above surface modification will be described as follows. 1. A symmetric or asymmetric array of protrusions is formed. 1) A form of two or more rows is adopted. 2) In the formed metal wire, the minimum distance between each protrusion structure is restricted to be within a certain range or smaller. Specifically, this range is small enough to restrict the liquid to which capillary force is applied. 3) The change in the protrusion groups of two adjacent rows is small. That is, the applied liquid is restricted within the gap formed by the two adjacent rows of protrusion arrays. 2. The applied liquid is restricted between two or more lines. 1) Specifically, the gap between the protrusion groups of two adjacent rows is smaller than the width of the metal wire on the untreated surface. 2) Specifically, the minimum distance between the protrusion groups of two adjacent rows is 10 μm. 3) The gap between two adjacent protrusion structures within the same row is small, so the capillary force restricts the applied liquid. 3. The height of the protrusion structure is sufficient to restrict the applied liquid. 1) The tension is determined by the applied liquid. 2) Due to surface tension and other aspects, the height of the protrusion structure can be smaller than the final thickness of the metal grid line.

[0025] The method for manufacturing the above protrusion structure will be described as follows. 1. Pulse laser processing is adopted. 2. The wavelength of the laser light is at least larger than the optical bandgap of the upper layer material. Note that the upper layer material does not absorb the laser light. Generally, the upper layer material refers to the front electrode and / or buffer layer / i layer and / or absorber. Furthermore, in order to melt / evaporate the material on the inner surface and protrude the material to the top, the wavelength of the laser light is smaller than the optical bandgap of the material of one of the subsequent layers. Note that the subsequent layer of the material absorbs the laser light. Generally, the subsequent layer is at the interface between the absorption layer and the buffer layer. 3. The laser power is selected within the range necessary to form the protruding structure. If the power is too high, it will cause ablation; if it is too low, it will cause failure to form the protrusions. 4. Generally, thin-film technology consists of at least two layers, and it is desirable to coat a narrow line on top of one of the layers. 5. Photovoltaic modules such as CIGS, CdTe, and perovskite are available. 6. The substrate is provided with a thin-film PV module and a cover layer. 7. Metal grid processes for coating liquid, solvent, or aqueous metal wires include inkjet, aerosol jet, screen printing, and dispensing. 8. The material of the liquid to be applied is generally a liquid, and may be a metallic ink or a dielectric ink. 9. The liquid may be applied once and / or multiple times. 10. The surface modification-based aspect ratio optimization method of the present invention is applicable to the design of metal grid lines (substrate or superstraight structure) of front and / or back electrodes.

[0026] To achieve the above objective, the photovoltaic module having the aspect ratio of a metal grid based on surface modification adopted in this application is Front electrode and, A group of protrusions formed on the front electrode, wherein each group of protrusions includes at least two protrusion structures, at least two rows of protrusion groups form a pair of protrusion arrangements, a gap is formed between two adjacent groups of protrusions to limit the width of the liquid to be applied, and a difference in height is formed between the top of the protrusion and the upper surface of the front electrode to limit the relatively large thickness of the liquid to be applied, The above-mentioned protrusions are formed by laser induction on the front electrode.

[0027] Specifically, the front electrode includes a liquid coating area and a liquid leakage prevention area, the liquid coating area includes, in the thickness direction, liquid, front electrode, buffer layer, absorber and back electrode, or liquid, front electrode and back electrode in that order, and the liquid leakage prevention area includes the back electrode in the thickness direction.

[0028] Specifically, the wavelength of the laser light is greater than the optical band gap of the front electrode material, but smaller than the optical band gap of the material at the interface between the buffer layer and the absorber.

[0029] Specifically, the above-mentioned protrusion arrangement may include juxtaposed arrangements, staggered arrangements, and irregular arrangements, and the spacing between two adjacent rows of protrusion groups may be greater than 10 μm, while the spacing between two adjacent protrusion structures within the same row may be 50 nm.

[0030] Specifically, the laser light mentioned above is pulsed laser light.

[0031] The surface modification-based method for optimizing the aspect ratio of a metal lattice, as described in this application, has the following beneficial effects.

[0032] This application proposes a method for optimizing the aspect ratio of a metal grid based on surface modification. This optimization method aims to reduce shading of metal wires and ensure low series resistance by applying metal grid wires having the minimum width and sufficient thickness. The objective of this disclosure is to optimize the aspect ratio by modifying the surface of the front electrode.

[0033] This invention proposes a photovoltaic module having a metal grid aspect ratio based on surface modification, and in particular improves the aspect ratio of the metal grid lines by modifying the surface of the front electrode of the thin-film solar cell.

[0034] Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, illustrating how the principles of the present application can be applied. It should be understood that the embodiments of the present application include many changes, modifications and equivalents, and are not limited thereto. [Brief explanation of the drawing]

[0035] [Figure 1] This is a schematic diagram showing the stacked structure of a thin-film solar cell commonly used in conventional technology. [Figure 2] This is a schematic diagram of the cell width and dead area structure of a standard thin-film solar cell in the prior art, and is a plan view of Figure 1. [Figure 3] This is a schematic diagram of the planar structure of the connection relationship between three cells in a standard thin-film PV module using conventional technology. [Figure 4] This is a schematic diagram showing the current in the metal grid within a cell in the conventional technology. [Figure 5] This is a schematic diagram using the conventional ALD (Aluminum Wire Deposition) process. [Figure 6A] This is a schematic diagram illustrating the inkjet coating of the front electrode of a solar cell using conventional technology. [Figure 6B] This is a schematic diagram showing the distribution of the liquid film (i.e., ink) on the front electrode in the conventional technology. [Figure 7A] This figure shows the application of pulsed laser light, which is less than the band gap of the front electrode and buffer layer, to two points on the surface of the solar cell in this application. [Figure 7B] This figure shows the protrusion of the front electrode and buffer layer material on the surface of a solar cell due to the application of pulsed laser light. [Figure 8A] This is a grayscale 2D image taken with a confocal microscope, showing a protrusion formed on the front electrode in this application. [Figure 8B] This is a grayscale 3D image taken with a confocal microscope, and is a visualization of Figure 8A. [Figure 9]This is a cross-sectional image of two rows of protrusions formed on the front electrode according to the present invention. [Figure 10A] This figure shows ink application between protrusions formed on the surface of a thin-film solar cell. [Figure 10B] This figure shows how the formed protrusions limit and uniformly distribute the ink. [Figure 11A] This figure shows a projection array formed in a symmetrical manner. [Figure 11B] This diagram shows an array of protrusions formed in a staggered pattern. [Figure 11C] This figure shows an array of protrusions formed in an irregular manner. [Figure 12] This is a schematic cross-sectional bottom view of a thin-film solar cell stack having a metal grid according to the present invention. [Figure 13] This is a schematic plan view of the grid width and grid pitch of a thin-film solar cell having a metal grid in the present invention. [Figure 14] This is a schematic plan view of the interconnection between three cells of a thin-film PV module having a metal grid in the present invention. [Modes for carrying out the invention]

[0036] To further clarify the purpose, technical proposal, and advantages of this application, the application will be described in more detail below with reference to the attached drawings and embodiments. However, it should be understood that the specific embodiments described herein are used solely for the purpose of interpreting this application and not to limit its scope.

[0037] When a component is described as being "installed" or "mounted" on another component, it may be directly located on the other component, or an intermediate component may be present. When one component is considered to be "connected" or "connected to" another component, it may be directly connected to the other component, or an intermediate component may be present simultaneously. "Fixed" means a fixed connection, and fixed connections include various methods that are not considered to be within the scope of protection of this specification. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not imply that they represent only one embodiment.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as that generally understood by those skilled in the art of this application. Terms used herein are used solely for the purpose of describing specific embodiments and are not intended to limit this application. The terms “and / or” as used herein include all combinations of one or more related items listed.

[0039] To reduce the line width expansion of metal wires as shown in Figure 6, we propose a method for forming a portion of the front electrode, i.e., a method for optimizing the aspect ratio of a metal grid based on surface modification. The method according to this application is used to induce the formation of regular or irregular protrusions upward on a front electrode made of the material of the front electrode, such that the applied ink and / or paste is limited to between two or more lines.

[0040] Referring to the drawings, specific embodiments of the surface modification-based aspect ratio optimization method for metal lattices according to this application will be described. As shown in the figure, Figure 7 is the cause of the formation of protrusion structures. Specifically, Figure 7A shows the application of pulsed laser light below the band gap of the front electrode and buffer layer at two points on the surface of the solar cell in this application, and Figure 7B shows the protrusion of the front electrode and buffer layer material on the solar cell surface due to the application of pulsed laser light. Specifically, a method for applying a pulsed laser with a wavelength of 1064 nm to a thin-film CIGS solar cell for about 15 ps was tested. Because the energy of the laser light was significantly smaller than the band gap of the corresponding material, the laser light was not absorbed by the TCO and buffer layer. Therefore, because the band gap of the absorption layer is lower than the energy of the laser light, the laser light passes through the upper layer and is absorbed at the interface between the absorption layer and the buffer layer. The absorption of a single laser pulse causes local melting and evaporation of the absorption layer and buffer layer material in the stack, and the laser light power should be selected so that small protrusions are formed on the surface of the front electrode. Too little power will only cause localized heating and will not form any protrusions, thus having no limiting effect. Too much power will cause complete ablation of the buffer layer and front electrode layer, leading to line width expansion and increased series resistance in the interconnection region, and significantly reducing the thickness between the metal grid and the front electrode (ink / paste material fills the resulting holes). The maximum thickness of the protrusion is the sum of the thickness of the front electrode layer and the buffer / i layer. The laser power used to form the desired protrusion mainly depends on the thickness and material composition of the buffer layer and front electrode, specifically including aspects such as hardness, stiffness, tension, and tackiness.

[0041] Figures 8 and 9 show images of such protruding structures formed on the front electrode of a thin-film solar cell.

[0042] Specifically, Figure 8 is a grayscale image taken with a confocal microscope, with Figure 8A being a 2D image and Figure 8B being a 3D image. The limiting condition is that two groups of protrusions are formed on the front electrode to limit the liquid to be applied, which may be an ink or paste, and the shown structure was generated when the target distance was 20 μm.

[0043] Figure 9 is a cross-sectional image of two rows of protrusions formed on the front electrode. The structure shown was generated when the target distance was 10 μm. The average height of the achieved protrusions is approximately 170 nm, and the maximum height is greater than 170 nm. The width of the generated protrusion structure is within the range of approximately 10 μm.

[0044] Furthermore, the formed protrusions typically have an irregular shape, with heights ranging from several hundred nanometers to several nanometers, depending specifically on the thickness of the buffer layer and the front electrode. Some protrusions may develop small cracks, indicating depletion of the evaporation material, and the width of these protrusions is within the range of several hundred nanometers.

[0045] Furthermore, the morphology of the protrusion structure is adjusted according to the liquid used and the desired width and thickness of the resulting metal grid wire. The liquid includes ink or paste. In several tests, when the width of the protrusion structure is within the range of 10 μm, the minimum distance between two adjacent rows of protrusion groups is approximately 10 μm, as shown in Figure 9. If the above distance is smaller, a single protrusion structure is formed that does not have a restricting space for liquid filling.

[0046] Figure 10 shows that a restricting space formed by two or more rows of protrusions within a certain distance from each other can restrict and fill a liquid. Specifically, Figure 10A shows liquid application between protrusions formed on the surface of a thin-film solar cell, and Figure 10B shows a protrusion structure that restricts and uniformly distributes ink.

[0047] Figure 11 shows a possible embodiment of forming a protrusion structure using pulsed laser light. Specifically, in Figure 11, the distance between two rows of protrusion groups is defined as w1, which also specifies the width of the metal grid lines. Distance w2 is the spacing between two adjacent protrusion structures in the same row, and this spacing must be set sufficiently small to ensure that capillary forces restrict the liquid between the two lines, i.e., there is no leakage between two adjacent protrusion structures in the same column.

[0048] Specifically, Figure 11A shows a symmetrical array of protrusions, Figure 11B shows a staggered array of protrusions, and Figure 11C shows an irregular array of protrusions.

[0049] The aforementioned projection array may also be considered a projection arrangement.

[0050] Furthermore, in the examples shown in Figures 8 and 9, a distance w1 of several tens of micrometers, a distance w2 within a range of several micrometers, and a height of several hundred nanometers are particularly suitable for inkjet process applications, mainly because the distance w2 is small enough that capillary force effectively restricts the ink within the two lines generated, and the height is sufficient to prevent material from overflowing from the protruding structure.

[0051] Of course, the aspect ratio optimization method for metal grids based on the surface modification described above is applicable not only to single-pass technology but also to various other technologies, particularly inkjet processes. Specifically, this invention helps prevent line width expansion due to small misalignments in high-speed ink application alignment during mass production.

[0052] Figures 12 to 14 illustrate the metal grid. Specifically, Figure 12 shows a stacked cross-sectional view of a thin-film solar cell having a metal grid wire structure, Figure 13 shows a schematic plan view of the grid width and grid pitch of a thin-film solar cell having a metal grid, and Figure 14 shows a plan view of the interconnection between three cells in a thin-film PV module having a metal grid.

[0053] Specifically, in Figures 12 to 14, the metal grid structure is applied laterally to the cell at periodic intervals, or perpendicular to P1, P2, and P3. These metal grid structures are applied continuously to the solar cell, with P3 interrupting the metal grid to prevent short circuits between the front electrodes of one cell and the front electrodes of adjacent cells.

[0054] Based on the above, the method for optimizing the aspect ratio of the metal lattice based on the surface modification described above will be explained as follows. 1. A symmetrical or asymmetrical array of protrusions is formed. 1) A format of two lines or more is adopted. 2) In the formed metal wire, the minimum distance between each protruding structure is limited to a certain range or less, specifically, a range that is small enough for capillary force to limit the coated liquid. 3) The variation between two adjacent rows of protrusions is small. That is, the applied liquid is confined to the gap formed by the two adjacent rows of protrusion arrays. 2. The applied liquid is limited to between two or more lines. 1) Specifically, the gap between two adjacent rows of protrusion groups is smaller than the width of the metal wire on the untreated surface. 2) Specifically, the minimum distance between two adjacent rows of protrusion groups is 10 μm. 3) Because the gap between two adjacent protrusions within the same row is small, capillary force restricts the applied liquid. In the case of CIGS, this gap is several micrometers. 3. The height of the protruding structure is sufficient to limit the liquid to which it is applied. 1) The tension is determined by the liquid being applied. 2) Due to surface tension and other factors, the height of the protruding structure can be less than the final thickness of the metal grid wire.

[0055] The method for manufacturing the above-mentioned protruding structure is described below. 1. Pulse laser processing is employed. 2. The wavelength of the laser light is at least greater than the optical band gap of the upper layer material. The upper layer material either does not absorb the laser light or absorbs only a small amount of it (e.g., less than 20%). Typically, the upper layer material refers to the front electrode and / or buffer layer / i layer and / or absorption layer. Furthermore, in order to melt / evaporate the material on the inner surface and cause the material to protrude, the wavelength of the laser light is smaller than the optical band gap of the material in one of the subsequent layers. Note that the subsequent layer of the material absorbs the laser light, and generally, this subsequent layer is located at the interface between the absorbing layer and the buffer layer. 3. The laser power is selected within the range necessary to form the protruding structure. If the power is too high, it will cause ablation; if it is too low, it will cause failure to form the protrusions. 4. Generally, thin-film technology consists of at least two layers, and it is desirable to coat a narrow line on top of one of the layers. 5. Photovoltaic modules such as CIGS, CdTe, and perovskite are available. 6. The substrate is provided with a thin-film PV module and a cover layer. 7. Metal grid processes for coating liquid, solvent, or aqueous metal wires include inkjet, aerosol jet, screen printing, and dispensing. 8. The material of the liquid to be applied is generally a liquid, and may be a metallic ink or a dielectric ink. 9. The liquid may be applied once and / or multiple times. 10. The surface modification-based aspect ratio optimization method of the present invention is applicable to the design of metal grid lines (substrate or superstraight structure) of front and / or back electrodes.

[0056] The following example provides a method for forming the aforementioned protruding structure.

[0057] Let's take a CIGS with an AZO thickness of 750 nm and a ZnOS thickness of 65 nm as an example.

[0058] With a wavelength of 1064 nm, a laser pulse of 15 ps, a repetition rate of 500 kHz, a speed of 10800 mm / min, and a process window of approximately 20 μm (2 w0), the laser power is 150 mW to 250 mW.

[0059] Furthermore, the photovoltaic module having the aspect ratio of the metal grid based on surface modification adopted in this application, Front electrode and, A group of protrusions formed on the front electrode, wherein each group of protrusions includes at least two protrusion structures, at least two rows of protrusion groups form a pair of protrusion arrangements, a gap is formed between two adjacent groups of protrusions to limit the width of the liquid being applied, and a difference in height is formed between the top of the protrusion and the upper surface of the front electrode to limit the thickness of the liquid being applied, The above-mentioned protrusions are formed by laser induction on the front electrode.

[0060] Specifically, the front electrode includes a liquid coating area and a liquid leakage prevention area, the liquid coating area includes, in the thickness direction, liquid, front electrode, buffer layer, absorber and back electrode, or liquid, front electrode and back electrode in that order, and the liquid leakage prevention area includes the back electrode in the thickness direction.

[0061] Specifically, the wavelength of the laser light is greater than the optical band gap of the front electrode material, but smaller than the optical band gap of the material at the interface between the buffer layer and the absorber.

[0062] Specifically, the above-mentioned protrusion arrangement may include juxtaposed arrangements, staggered arrangements, and irregular arrangements, and the spacing between two adjacent rows of protrusion groups may be greater than 10 μm, while the spacing between two adjacent protrusion structures within the same row may be 50 nm.

[0063] Specifically, the laser light mentioned above is pulsed laser light.

[0064] In the drawing, the front electrode is represented by reference numeral 1, the buffer layer by reference numeral 2, the absorber by reference numeral 3, and the back electrode by reference numeral 4.

[0065] The foregoing describes only preferred embodiments of the present application and is not intended to limit it. Any modifications, substitutions with equivalents, or improvements made within the scope of the essence and principles of the present application should all be included within the scope of protection.

Claims

1. A method for manufacturing a solar power generation module, The aforementioned solar power generation module is Front electrode and, The buffer layer below the front electrode, The absorber below the buffer layer, The back electrode below the absorber, A group of protrusions formed on the front electrode, wherein each group of protrusions includes at least two protrusion structures, at least two rows of protrusion groups form a set of protrusion arrangements, a gap is formed between two adjacent groups of protrusions to limit the width of the liquid to be applied, and a height difference is formed between the top of the protrusion and the upper surface of the front electrode to limit the thickness of the liquid to be applied; Includes, The method for manufacturing the aforementioned solar power generation module is: A step of forming the group of protrusions using laser light, wherein the laser light is absorbed at the interface between the buffer layer and the absorber, and the group of protrusions protrudes upward from the interface between the buffer layer and the absorber and penetrates the front electrode. A method for manufacturing a solar power generation module, characterized by including the following:

2. The wavelength of the laser light is greater than the wavelength corresponding to the optical band gap of the material of the front electrode, and less than the wavelength corresponding to the optical band gap of the material at the interface between the buffer layer and the absorber. A method for manufacturing a solar power generation module according to claim 1.

3. The aforementioned arrangement of protrusions is one of the following: a juxtaposed arrangement, a staggered arrangement, or an irregular arrangement. A method for manufacturing a solar power generation module according to claim 1 or 2.

4. The spacing between two adjacent rows of protrusions is greater than 10 μm in both cases. A method for manufacturing a solar power generation module according to claim 1 or 2.

5. The laser light is pulsed laser light. A method for manufacturing a solar power generation module according to claim 1 or 2.

6. The aforementioned solar power generation module includes one of CIGS, CdTe, or perovskite. A method for manufacturing a solar power generation module according to claim 1 or 2.

7. The liquid includes a metallic ink or a dielectric ink. A method for manufacturing a solar power generation module according to claim 1 or 2.

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