Electrode pattern of tunneling oxide layer back contact cell

Abstract

The utility model relates to the field of photovoltaic cell manufacturing, in particular to an electrode pattern of a tunneling oxide layer back contact cell, which comprises a silicon wafer and a silver grid line attached to the silicon wafer. The silver grid lines comprise fine grid lines, frame lines and harpoon lines; according to the utility model, by optimizing the design of the electrode diagram, the adhesive force between the silver grid line and the silicon wafer is improved, so that the overall reliability and durability of the photovoltaic cell are improved; and secondly, the corners of the electrode pattern are designed in a fillet and arc transition manner, so that the phenomenon that the silver grid lines fall off due to stress concentration is reduced, and the mechanical stability of the electrode is improved.

Description

Technical Field

[0001] The utility model relates to the field of photovoltaic cell manufacturing, in particular to an electrode pattern of a back contact cell through a tunnel oxide layer. Background Art

[0002] In the photovoltaic industry, tunnel oxide back contact cells (TOPCon) have become a mainstream photovoltaic cell technology due to their high photoelectric conversion efficiency. This technology relies on the silver grid lines to effectively conduct the generated current and maximize the photoelectric conversion efficiency through the optimized design of the electrode pattern. However, the existing electrode pattern design has some significant problems in practical applications.

[0003] First, the existing electrode patterns are prone to the problem of silver grid lines falling off during use. The falling off of silver grid lines will not only cause incomplete electrodes, but also affect the photoelectric conversion efficiency, resulting in a decrease in the appearance quality of the battery. In severe cases, it will even affect the service life of the entire battery.

[0004] In addition, with the continuous improvement of photovoltaic cell production technology, the cells are becoming thinner and thinner, and the design requirements of electrode patterns are becoming higher and higher. However, the commonly used silver paste materials have weak corrosion resistance when in contact with silicon wafers, resulting in insufficient adhesion, which further increases the risk of silver grid lines falling off.

[0005] Therefore, the prior art urgently needs an improved electrode pattern design to solve the above problems and improve the stability and performance of photovoltaic cells. Utility Model Content

[0006] The technical problem to be solved by the utility model is the problem that the silver grid lines are easy to fall off in the existing electrode pattern design. The purpose is to provide an electrode pattern that contacts the battery from the back of the tunnel oxide layer, which reduces the stress concentration effect and enhances the adhesion between the silver grid lines and the silicon wafer, thereby reducing the falling off of the silver grid lines and improving the stability and photoelectric conversion efficiency of the photovoltaic cell.

[0007] The utility model is realized by the following technical solutions:

[0008] An electrode pattern of a back contact battery through a tunnel oxide layer includes: a silicon wafer and a silver grid line attached to the silicon wafer; the silver grid line includes: a thin grid line, a frame line and a harpoon line;

[0009] Two groups of border lines separate the silicon wafer into a first frame body and a second frame body, and a plurality of the fine gate lines are distributed in parallel on the silicon wafer and are located in the first frame body and the second frame body respectively;

[0010] The frame line includes two horizontal lines and two vertical lines. The two horizontal lines are arranged in parallel with the thin grid lines. The two ends of the thin grid lines are respectively connected to the two vertical lines. The plurality of harpoon lines are connected to the horizontal lines.

[0011] Specifically, a plurality of the harpoon lines are arranged in pairs on two of the transverse lines, and a connecting line between the two harpoon lines is perpendicular to the transverse lines.

[0012] Specifically, the fine grid lines include continuous lines and discontinuous lines, and a plurality of continuous lines and one discontinuous line are sequentially and spaced apart and distributed in the frame line;

[0013] The transverse lines include a plurality of short lines distributed in a straight line, and the adjacent short lines are not connected and are arranged corresponding to the discontinuities of the discontinuous lines.

[0014] Specifically, the harpoon line includes a first oblique line and a second oblique line, and the distance between the outer end of the first oblique line and the outer end of the second oblique line is greater than the distance between the inner end of the first oblique line and the inner end of the second oblique line;

[0015] The outer ends of the first oblique line and the second oblique line are respectively connected to the two ends of the short line;

[0016] The inner ends of the first oblique line and the second oblique line are not connected to the thin gate line and are located at the discontinuity of the discontinuous line, and the middle parts of the first oblique line and the second oblique line are connected to the continuous line.

[0017] Specifically, a rounded transition line is provided between the outer end of the first oblique line and the short line, and a rounded transition line is provided between the outer end of the second oblique line and the short line.

[0018] Optionally, the radius of the rounded transition line is 0.71±0.20 mm.

[0019] Specifically, the outer side transverse line of the first frame is connected to the two vertical lines of the first frame via a chamfer; the outer side transverse line of the second frame is connected to the two vertical lines of the second frame via a chamfer.

[0020] Furthermore, a first arc-shaped transition line is provided between the chamfer and the transverse line, and a second arc-shaped transition line is provided between the chamfer and the vertical line.

[0021] Optionally, the radius of the first arc-shaped transition line is 1.71±0.20 mm, and the radius of the second arc-shaped transition line is 1.55±0.20 mm.

[0022] The minimum distance between the first frame and the second frame is 1.14±0.20mm, the length of the short line is 10.80±0.20mm, the distance between the outer end of the first oblique line and the outer end of the second oblique line is 1.23±0.20mm, the distance between the inner end of the first oblique line and the inner end of the second oblique line is 0.55±0.20mm, the distance between two adjacent fine gate lines is 1.14±0.20mm, and the length and width of the silicon wafer are both 180.80±0.20mm.

[0023] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0024] The utility model improves adhesion by optimizing the composition of electrode patterns, and reduces stress concentration effect by optimizing the geometric structure of the electrode to prevent the silver grid lines from falling off. The electrode patterns include thin grid lines, frame lines and harpoon lines attached to a silicon wafer. In order to reduce the stress concentration effect, the horizontal lines and vertical lines of the frame lines are connected by chamfers, and arc transition lines are arranged at the chamfers; at the same time, a rounded transition line is arranged between the harpoon line and the frame line, so that the electrode patterns can reduce stress concentration at the corners while maintaining current flow.

[0025] The utility model improves the adhesion between the silver grid line and the silicon wafer by optimizing the design of the electrode pattern, thereby improving the overall reliability and durability of the photovoltaic cell; secondly, the rounded corners and arc transition design are adopted at the corners of the electrode pattern to reduce the silver grid line shedding phenomenon caused by stress concentration and improve the mechanical stability of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, are used to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention, and the accompanying drawings are included in and constitute a part of this specification and do not constitute a limitation on the embodiments of the present invention.

[0027] Figure 1 It is a structural schematic diagram of an electrode pattern of a back contact battery through an oxide layer according to the utility model.

[0028] Figure 2 It is an enlarged schematic diagram of part A of an electrode pattern of a tunnel oxide layer back contact battery according to the utility model.

[0029] Figure numerals: 1-border line, 2-thin grid line, 3-harpoon line, 11-first frame, 12-second frame, 13-horizontal line, 14-vertical line, 21-continuous line, 22-interrupted line, 31-first oblique line, 32-second oblique line. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and implementation methods. It is understood that the specific implementation methods described here are only used to explain the relevant content, rather than to limit the utility model.

[0031] It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the drawings.

[0032] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] In the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In the process of daily use of photovoltaic cells, the inventors gradually discovered that the adhesion between the silver grid wire and the silicon wafer was insufficient, which often caused the silver grid wire to fall off. This phenomenon not only affects the photoelectric conversion efficiency of photovoltaic cells, but also has a negative impact on the overall life and reliability of the battery. Although this problem has troubled many technicians, the root cause of the silver grid wire falling off has not been found for a long time. Traditional solutions focus on material modification and process optimization, but have failed to effectively curb the occurrence of this problem.

[0036] After in-depth observation and research, the utility model inventor found that the shedding of silver grid lines is actually closely related to stress concentration. During the manufacture and use of photovoltaic cells, silver grid lines are subject to the combined effects of a variety of physical, chemical and electrical factors, such as thermal stress caused by temperature changes, chemical properties of silver paste materials, and electrical stress generated during current conduction. These stresses tend to concentrate at the corners and intersections of the electrode pattern, thus causing the shedding of the silver grid lines.

[0037] Stress refers to the force inside a material that resists deformation due to external forces. For the electrode diagram in a photovoltaic cell, the sources of stress generally include:

[0038] Thermal stress: Temperature changes during manufacturing and use can cause the material to expand or contract. If the thermal expansion coefficients of the electrode material and the substrate material are different, temperature changes can cause different parts of the material to expand or contract to different degrees, thus generating stress.

[0039] Mechanical stress: During manufacturing, handling or installation, the electrode pattern may be subjected to external forces such as pressure, friction or impact, etc. These external forces can cause material deformation and thus generate stress.

[0040] Chemical stress: In some cases, electrode materials may react with chemicals in the environment, causing changes in the material's volume or morphology, which in turn induces stress.

[0041] After research by the utility model inventor, it was found that stress in some local areas is greater than in other areas, that is, stress concentration usually occurs at geometric discontinuities in the material structure, such as corners and sharp turns. In the electrode diagram, when external forces or internal stresses (such as thermal stress) are applied to this area, the material in the right-angle area will be subjected to greater stress than other areas. If the stress exceeds the yield strength of the material, the material may begin to deform, crack, or even break, causing the silver grid to fall off.

[0042] In response to this discovery, the utility model inventor designed a technical solution specifically to reduce stress concentration by optimizing the geometric structure of the electrode pattern, such as using rounded transition lines and arc chamfer designs to effectively disperse stress, thereby fundamentally solving the problem of silver grid line falling off.

[0043] Embodiment 1

[0044] like Figure 1 and Figure 2 As shown, an electrode pattern of a tunneling oxide back contact battery includes: a silicon wafer and a silver grid line attached to the silicon wafer; the tunneling oxide back contact battery uses the tunneling effect to form a good electrical contact between the oxide layer and the silicon wafer to improve the photoelectric conversion efficiency of the battery. Its design focuses on the reasonable layout of the electrode pattern to ensure the effective collection and conduction of current.

[0045] As the main semiconductor material of photovoltaic cells, silicon wafers generate photogenerated electrons by absorbing light energy. Silver grid lines are conductive patterns printed on the surface of silicon wafers to collect and conduct photogenerated current. Silver grid lines are composed of multiple parts, including fine grid lines 2, frame lines 1 and harpoon lines 3.

[0046] The fine grid lines 2 are distributed in parallel on the surface of the silicon wafer and are responsible for conducting current from the photovoltaic area to the frame lines 1. The fine grid lines 2 can be continuous or discontinuous.

[0047] The frame line 1 includes two horizontal lines 13 and two vertical lines 14, forming an outer frame of the electrode pattern. The horizontal lines 13 are parallel to the thin grid lines 2, and the two ends of the thin grid lines 2 are respectively connected to the vertical lines 14 to form a current conduction loop.

[0048] The harpoon wire 3 is a conductive wire connected to the transverse wire 13, and is generally in the shape of an oblique line. The harpoon wires 3 are arranged in pairs and are arranged perpendicular to the transverse wires 13. The harpoon wires 3 help to distribute stress more evenly and optimize the derivation of current through their geometric structure.

[0049] In the design of this embodiment, two groups of border lines 1 separate the silicon wafer into a first frame body 11 and a second frame body 12, and multiple fine grid lines 2 are distributed in parallel on the silicon wafer and are respectively located in the first frame body 11 and the second frame body 12; this facilitates the current generated by the silver grid lines to be diverted to the two border lines 1, thereby reducing the current of a certain border line 1 and reducing its heat generation.

[0050] The frame line 1 includes two horizontal lines 13 and two vertical lines 14 . The two horizontal lines 13 are arranged parallel to the thin grid lines 2 . The two ends of the thin grid lines 2 are respectively connected to the two vertical lines 14 . The multiple harpoon lines 3 are all connected to the horizontal lines 13 .

[0051] Specifically, a plurality of harpoon lines 3 are arranged in pairs on two transverse lines 13 , and a connecting line between two oppositely arranged harpoon lines 3 is perpendicular to the transverse line 13 .

[0052] The fine grid lines 2 include continuous lines 21 and discontinuous lines 22 , and a plurality of continuous lines 21 and one discontinuous line 22 are sequentially spaced apart in the frame line 1 ; the transverse lines 13 include a plurality of short lines distributed in a straight line, and adjacent short lines are not connected and are arranged corresponding to the discontinuities of the discontinuous lines 22 .

[0053] The discontinuous lines 22 and the transverse lines 13 are arranged as a discontinuous structure so that the stress in the electrode pattern will not be excessively concentrated on a straight line, and the mechanical stress and thermal stress on the material can be effectively dispersed, thereby reducing the risk of material breakage or damage caused by stress concentration.

[0054] The harpoon line 3 includes a first oblique line 31 and a second oblique line 32, and the distance between the outer end of the first oblique line 31 and the outer end of the second oblique line 32 is greater than the distance between the inner end of the first oblique line 31 and the inner end of the second oblique line 32; the outer end of the first oblique line 31 and the outer end of the second oblique line 32 are respectively connected to the two ends of the short line; the inner end of the first oblique line 31 and the inner end of the second oblique line 32 are not connected to the fine grid line 2, and are located at the discontinuity of the discontinuous line 22, and the middle part of the first oblique line 31 and the middle part of the second oblique line 32 are connected to the continuous line 21.

[0055] The design of the harpoon line 3 is composed of two oblique lines, and the distance between the outer ends is greater than the distance between the inner ends. The purpose is: the larger distance between the outer ends makes the outer end of the harpoon line 3 closer to the frame line 1, which helps to quickly introduce the collected current into the frame line 1, and can reduce the length of the current conduction path, thereby reducing resistance and improving current conduction efficiency.

[0056] And in the electrode diagram, stress concentration often occurs where the geometry changes sharply. The outer end distance of the harpoon line 3 is greater than the inner end distance, so that the current and stress can be smoothly dispersed near the frame line 1, reducing the possibility of stress concentration at one point, thereby reducing the risk of silver grid line falling off.

[0057] Embodiment 2

[0058] like Figure 1 and Figure 2 As shown, a rounded transition line is provided between the outer end of the first oblique line 31 and the short line, and a rounded transition line is provided between the outer end of the second oblique line 32 and the short line. In practice, the rounded transition line can be provided only at the harpoon line 3 located at the edge of the battery.

[0059] The outer transverse line 13 of the first frame 11 is connected to the two vertical lines 14 of the first frame 11 by chamfering; the outer transverse line 13 of the second frame 12 is connected to the two vertical lines 14 of the second frame 12 by chamfering.

[0060] A first arc-shaped transition line is provided between the chamfer and the transverse line 13 , and a second arc-shaped transition line is provided between the chamfer and the vertical line 14 .

[0061] The rounded transition line / arc transition line can effectively reduce stress. Under the action of thermal stress, different materials expand or contract to different extents, and the right angle will concentrate greater stress due to sudden geometric changes. The rounded / arc corner design makes the thermal stress more evenly distributed in the transition area, avoiding local stress concentration caused by sharp corners, thereby reducing the risk of silver grid line falling off.

[0062] Under the action of mechanical stress, rounded corners / arc corners can alleviate local deformation caused by pressure, friction or impact. Compared with right angles, rounded corners / arc corners disperse the distribution of external forces on the surface of the material, making the deformation of the material under the action of external forces more uniform and reducing the possibility of breakage or falling off.

[0063] Volume changes in materials caused by chemical reactions are often concentrated on the surface. The rounded / arc-corner design provides a larger surface area and a more uniform stress distribution area, reducing the possibility of stress concentration in a single location, thereby preventing material failure.

[0064] Chamfering can effectively reduce stress. Under the action of thermal stress, the chamfer design reduces sudden geometric changes, making the transition smoother when the material expands or contracts due to temperature changes. Chamfering can alleviate stress concentration caused by differences in thermal expansion coefficients.

[0065] In the case of mechanical stress, the chamfer provides a gentle transition area so that the external force will not act directly on the sharp corners. This can effectively avoid material cracking or damage caused by mechanical stress.

[0066] For chemical stress, the chamfer design allows the material to have more space to adapt when the volume changes, reduces the stress concentration area, and prevents the material from cracking or peeling during deformation after chemical reaction.

[0067] By providing an arc-shaped transition line on the chamfer, the stress between the transverse line 13 and the vertical line 14 can be further reduced.

[0068] Embodiment 3

[0069] This embodiment provides a specific electrode image size for a battery, and the radius of the rounded transition line is 0.71±0.20 mm.

[0070] The radius of the first arc-shaped transition line is 1.71±0.20 mm, and the radius of the second arc-shaped transition line is 1.55±0.20 mm.

[0071] The minimum distance between the first frame 11 and the second frame 12 is 1.14±0.20mm, the length of the short line is 10.80±0.20mm, the distance between the outer end of the first oblique line 31 and the outer end of the second oblique line 32 is 1.23±0.20mm, the distance between the inner end of the first oblique line 31 and the inner end of the second oblique line 32 is 0.55±0.20mm, the distance between two adjacent fine gate lines 2 is 1.14±0.20mm, and the length and width of the silicon wafer are both 180.80±0.20mm.

[0072] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0074] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present invention, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above utility model, and these changes or modifications are still within the scope of the present utility model.

Claims

1. An electrode pattern of a tunnel oxide back contact battery, characterized in that: include: A silicon wafer and silver grid lines attached to the silicon wafer; the silver grid lines include: fine grid lines (2), frame lines (1) and harpoon lines (3); Two groups of border lines (1) separate the silicon wafer into a first frame body (11) and a second frame body, and a plurality of fine gate lines (2) are distributed in parallel on the silicon wafer and are located in the first frame body (11) and the second frame body, respectively; The frame line (1) comprises two transverse lines (13) and two vertical lines (14), the two transverse lines (13) are arranged parallel to the thin grid lines (2), the two ends of the thin grid lines (2) are respectively connected to the two vertical lines (14), and the plurality of harpoon lines (3) are connected to the transverse lines (13); A plurality of the harpoon lines (3) are arranged in pairs on two of the transverse lines (13), and a line connecting the two harpoon lines (3) is perpendicular to the transverse line (13); The fine grid lines (2) comprise continuous lines (21) and discontinuous lines (22), and a plurality of continuous lines (21) and one discontinuous line (22) are sequentially and spaced apart and distributed within the frame line (1); The transverse line (13) comprises a plurality of short lines distributed in a straight line, wherein adjacent short lines are not connected and are arranged corresponding to the discontinuities of the discontinuous line (22); The harpoon line (3) comprises a first oblique line (31) and a second oblique line (32), wherein the distance between the outer end of the first oblique line (31) and the outer end of the second oblique line (32) is greater than the distance between the inner end of the first oblique line (31) and the inner end of the second oblique line (32); The outer end of the first oblique line (31) and the outer end of the second oblique line (32) are respectively connected to two ends of the short line; The inner ends of the first oblique line (31) and the inner ends of the second oblique line (32) are not connected to the fine grid line (2) and are located at the discontinuity of the discontinuous line (22); the middle parts of the first oblique line (31) and the middle parts of the second oblique line (32) are connected to the continuous line (21).

2. The electrode pattern of a tunnel oxide back contact battery according to claim 1, characterized in that: A rounded transition line is provided between the outer end of the first oblique line (31) and the short line, and a rounded transition line is provided between the outer end of the second oblique line (32) and the short line.

3. The electrode pattern of a tunnel oxide back contact battery according to claim 2, characterized in that: The radius of the fillet transition line is 0.71±0.20 mm.

4. The electrode pattern of a tunnel oxide back contact battery according to claim 1, characterized in that: The transverse line (13) located on the outside of the first frame (11) and the two vertical lines (14) of the first frame (11) are connected by chamfers; the transverse line (13) located on the outside of the second frame and the two vertical lines (14) of the second frame are connected by chamfers.

5. The electrode pattern of a tunnel oxide back contact battery according to claim 4, characterized in that: A first arc-shaped transition line is provided between the chamfer and the transverse line (13), and a second arc-shaped transition line is provided between the chamfer and the vertical line (14).

6. The electrode pattern of a tunnel oxide back contact battery according to claim 5, characterized in that: The radius of the first arc-shaped transition line is 1.71±0.20 mm, and the radius of the second arc-shaped transition line is 1.55±0.20 mm.

7. The electrode pattern of a tunnel oxide back contact battery according to claim 1, characterized in that: The minimum distance between the first frame (11) and the second frame is 1.14±0.20 mm, the length of the short line is 10.80±0.20 mm, the distance between the outer end of the first oblique line (31) and the outer end of the second oblique line (32) is 1.23±0.20 mm, the distance between the inner end of the first oblique line (31) and the inner end of the second oblique line (32) is 0.55±0.20 mm, the distance between two adjacent fine gate lines (2) is 1.14±0.20 mm, and the length and width of the silicon wafer are both 180.80±0.20 mm.

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