CN117410359A - Back contact battery and manufacturing method thereof - Google Patents
Back contact battery and manufacturing method thereof Download PDFInfo
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- CN117410359A CN117410359A CN202311532174.8A CN202311532174A CN117410359A CN 117410359 A CN117410359 A CN 117410359A CN 202311532174 A CN202311532174 A CN 202311532174A CN 117410359 A CN117410359 A CN 117410359A
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- 239000004065 semiconductor Substances 0.000 claims abstract description 127
- 238000002161 passivation Methods 0.000 claims abstract description 112
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- 229910052782 aluminium Inorganic materials 0.000 claims description 16
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 16
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- 239000000463 material Substances 0.000 description 39
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- 238000007650 screen-printing Methods 0.000 description 2
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- 229910000449 hafnium oxide Inorganic materials 0.000 description 1
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Inorganic materials O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 1
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
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- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022433—Particular geometry of the grid contacts
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
- H01L31/0682—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
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- Life Sciences & Earth Sciences (AREA)
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Abstract
The invention discloses a back contact battery and a manufacturing method thereof, relates to the technical field of photovoltaics, and is used for improving the carrier collection capacity of a non-burn-through electrode. The back contact cell includes a semiconductor substrate, a surface passivation layer, a first electrode, and a second electrode. The surface passivation layer covers one side of the backlight surface of the semiconductor substrate and is provided with a conductive window, and part of the first area is exposed at the bottom of the conductive window. The first electrode and the second electrode are formed on the backlight surface side. The projection of at least part of the first electrode on the backlight surface is positioned in the first area. The projection of the second electrode on the backlight surface is positioned in the second area. The portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region. The minimum distance between the end of each contact region and the edge of the second region is a first distance, and the minimum distance between the end of each current collecting electrode section in the second electrode and the edge of the first region is a second distance. The first distance is less than the second distance.
Description
Technical Field
The invention relates to the technical field of photovoltaics, in particular to a back contact battery and a manufacturing method thereof.
Background
The back contact cell refers to a solar cell in which the positive electrode and the negative electrode are both on the back light surface of the cell, and the light surface of the back contact cell is not shielded by a metal electrode. Compared with a solar cell with a light-facing surface shielded, the back contact cell has higher short-circuit current and photoelectric conversion efficiency, and is one of the technical directions for realizing the high-efficiency crystalline silicon cell at present. And, the back passivation layer is formed on the back surface side of the semiconductor substrate included in the back contact battery, so that the carrier recombination rate on the back surface side of the semiconductor substrate can be reduced, and the working performance of the back contact battery is improved.
However, in the existing back contact battery with the back passivation layer, the carrier collection capability of the non-burn-through collector electrode included in the first electrode is poor, which is not beneficial to improving the photoelectric conversion efficiency of the back contact battery.
Disclosure of Invention
The invention aims to provide a back contact battery and a manufacturing method thereof, which are used for improving the carrier collection capacity of a non-burn-through electrode when the back contact battery is provided with a back passivation layer and the collector electrode included in a first electrode is the non-burn-through electrode, so that the photoelectric conversion efficiency of the back contact battery is improved.
In order to achieve the above object, the present invention provides a back contact battery including: the semiconductor device comprises a semiconductor substrate, a surface passivation layer, a first electrode and a second electrode. The backlight surface of the semiconductor substrate is provided with first areas and second areas which are alternately distributed. The first region and the second region are opposite in conductivity type. The surface passivation layer covers one side of the backlight surface. And a conductive window is arranged in the surface passivation layer, and part of the first area is exposed at the bottom of the conductive window. The first electrode and the second electrode are formed on the backlight surface side. The projection of at least part of the first electrode on the backlight surface is positioned in the first area. The projection of the second electrode on the backlight surface is positioned in the second area. The first electrode and the second electrode each include a plurality of collector electrodes and a plurality of bus electrodes. The first electrode includes bus electrodes and the second electrode includes bus electrodes that extend in a first direction and are alternately spaced apart in a second direction, the first direction being different from the second direction. The first electrode includes a collector electrode that is a non-burn-through electrode and is in ohmic contact with the first region through a conductive window. The collector electrode included by the second electrode is a burn-through electrode, part of the surface passivation layer is burned through and in ohmic contact with the second area, and the collector electrode included by the first electrode and the collector electrode included by the second electrode extend along the second direction and are alternately distributed at intervals along the first direction. Each collector electrode is connected with a collector electrode with the same polarity, and each collector electrode comprises a plurality of collector electrode sections which are distributed at intervals along the second direction, and the interval between every two adjacent collector electrode sections in the same collector electrode is used for isolating the collector electrode with the opposite polarity. Wherein a portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region. The minimum distance between the end of each contact area and the edge of the second area is the first distance along the second direction. In the second direction, the end of each current collecting electrode section in the second electrode is spaced apart from the edge of the first region by a second distance. The first distance is less than the second distance.
Under the condition of adopting the technical scheme, the collector electrode included in the first electrode is in ohmic contact with the first area through the conductive window formed in the surface passivation layer, and the collector electrode is used for collecting carriers of corresponding conductivity type in the first area and conducting the carriers to the collector electrode included in the first electrode. The second electrode includes a collector electrode that burns through a portion of the surface passivation layer and is in ohmic contact with the second region for collecting carriers of a corresponding conductivity type in the second region and conducting to a collector electrode included in the second electrode. Because of this, the first and second regions alternately arranged on the backlight side of the semiconductor substrate are opposite in conductivity type, so are the first and second electrodes. Meanwhile, a portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region. In the above case, in the second direction, the minimum distance (i.e., the first distance) between the end of each contact region and the edge of the second region serves to isolate the first electrode of opposite conductivity type from the second region, and the distance (i.e., the second distance) between the end of each collector electrode segment in the second electrode and the edge of the first region serves to isolate the second electrode of opposite conductivity type from the first region, preventing leakage and ensuring high electrical stability of the back contact cell.
Secondly, since each collector electrode included in the first electrode is a non-burn-through electrode and the surface passivation layer is a non-conductive insulating material layer, the contact range between each collector electrode in the first electrode and the first region is determined by the conductive window arranged in the surface passivation layer. In other words, in the process of actually manufacturing the back contact battery provided by the present invention, after the surface passivation layer provided with the conductive window is formed, when each collector electrode included in the first electrode is manufactured by the non-burn-through electrode paste, the non-burn-through electrode paste can only contact with a portion of the first region through the conductive window, which cannot penetrate the portion of the surface passivation layer where the conductive window is not provided. And each collector electrode included by the second electrode is a burn-through electrode, and a part of the surface passivation layer is burned through and in ohmic contact with the second region. In other words, in the actual manufacturing process of the back contact battery provided by the invention, the burn-through electrode for manufacturing each current collecting and collecting included in the second electrode can penetrate through the surface passivation layer, so that the electrical coupling with the region of the semiconductor substrate below the burned-through portion of the surface passivation layer is realized. In the above case, it is necessary to set the distance between the end of each collector electrode segment in the second electrode and the edge of the first region to a relatively large second distance in the second direction to prevent the end of each collector electrode segment in the second electrode from being overlapped with the first region to generate electric leakage. However, since the surface passivation layer is a non-conductive film layer, the minimum distance between the end of the contact region of ohmic contact between each current collecting electrode segment in the first electrode and the first region and the edge of the second region can be set to be a relatively small first distance, the free distance between the end of the contact region along the second direction and the edge of the second region can be reduced, and the carrier collecting capacity of each current collecting electrode segment included in the first electrode can be improved, so that the problem that the carrier recombination rate is high due to the fact that carriers of the corresponding conductivity type at the free distance are difficult to be conducted out in time due to the fact that the first distance is set to be equal to the second distance in the prior art can be solved, and the photoelectric conversion efficiency of the back contact battery can be improved.
As a possible implementation, in the second direction, the end of each collector electrode segment in the first electrode is flush with the end of the corresponding contact region. In this case, along the second direction, the actual manufacturing length of each collector electrode segment in the first electrode is approximately the same as the length for effectively collecting carriers (i.e., the distance between the two ends of the corresponding contact region along the second direction), so that the consumption of consumables of each collector electrode segment in the first electrode can be reduced, which is beneficial to reducing the manufacturing cost of the back contact battery.
As a possible implementation, in the second direction, the end of each collector electrode segment in the first electrode is located between the end of the contact region and the edge of the second region or above the second region. In this case, the actual manufacturing length of each collector electrode segment in the first electrode may be greater than the length of the effective collection carrier in the second direction. At this time, even if the end of each collector electrode segment in the first electrode in the second direction passes over the boundary between the first region and the second region and is located above the second region opposite to the conductivity type of the first electrode, the two can be isolated by the surface passivation layer, and higher manufacturing precision is not strictly required for manufacturing each collector electrode segment included in the first electrode with the end flush with the end of the corresponding contact region, so that the manufacturing difficulty of the back contact battery is reduced.
As a possible implementation, the first distance is 0. In this case, in the second direction, the end of the respective contact region corresponding to each collector electrode segment in the first electrode is aligned with the edge of the second region. In other words, the free distance between the end of the contact region along the second direction and the edge of the second region is 0, so that the effective carrier collection length corresponding to each collector electrode segment in the first electrode can be maximized, the corresponding conductive type carriers generated by the part of the first region corresponding to each collector electrode segment in the first electrode can be ensured to be collected and exported, the carrier recombination rate is further reduced, and the photoelectric conversion efficiency of the back contact battery is improved.
As a possible implementation, the second distance is greater than 0 and less than 0.4mm. In this case, the second distance is within the above-described range, and it is possible to prevent the leakage preventing effect between the end of each collector electrode segment in the second electrode in the second direction and the edge of the first region from being poor due to the small second distance, ensuring high electrical stability of the back contact battery. In addition, carriers of the corresponding conductivity type generated near the edge of the second region can be prevented from being difficult to collect at the end of each collector electrode segment in the second electrode along the second direction due to the large second distance, so that the higher carrier collecting capability of each collector electrode segment in the second electrode is ensured, and further the higher photoelectric conversion efficiency of the back contact battery is ensured.
As a possible implementation, the material of the collector electrode included in the first electrode includes aluminum, and the material of the collector electrode included in the second electrode includes silver.
With the above technical solution, aluminum and silver are commonly used electrode manufacturing materials for back contact batteries. When the material of the collector electrode included in the first electrode includes aluminum and the material of the collector electrode included in the second electrode includes silver, the manufacturing difficulty of the first electrode and the second electrode can be reduced, and the application range of the back contact battery provided by the invention can be enlarged.
As a possible implementation manner, the conductivity type of the first region is P-type, and the conductivity type of the second region is N-type.
Under the condition of adopting the technical scheme, the aluminum material is a common material for manufacturing the positive electrode in the back contact battery, so that an alloy layer is formed by the aluminum and the corresponding semiconductor material, and the contact resistance is reduced. Also, most of the electrode paste including aluminum is a non-burn-through type electrode paste. While silver material is a common material for manufacturing negative electrodes in back contact cells, and electrode paste in which part of the material includes silver is burn-through electrode paste. Based on the above, when the conductivity type of the first region is P-type and the conductivity type of the second region is N-type, the collector electrode included in the first electrode and the collector electrode included in the second electrode can be manufactured at least by using the aluminum material, so that the manufacturing difficulty of the first electrode and the second electrode is reduced, and the application range of the back contact battery provided by the invention can be enlarged.
As a possible implementation manner, the minimum distance between the edge of the bus electrode and the edge of the first area in the second electrode along the second direction is the third distance. The ratio of the third distance to the second distance is greater than or equal to 0.8 and less than or equal to 1.2.
With the above technical solution, the second distance and the third distance are respectively the distances between the end of the collector electrode segment in the second electrode and the edge of the bus electrode in the second direction and the edge of the first region opposite to the conductivity type of the bus electrode. Based on this, in the actual manufacturing process, the second distance and the third distance need to take into account machining errors of the bus electrode and the collector electrode segment in the second electrode, respectively, so that corresponding intervals are reserved to prevent the edges of the bus electrode and the ends of the collector electrode segment in the second electrode from overlapping to the first region with opposite conductivity types. The machining errors of the bus electrode and the collector electrode section included in the second electrode are approximately the same, so that when the ratio of the second distance to the third distance is more than or equal to 0.8 and less than or equal to 1.2, the two are approximately equal, and on the premise that the edge of the bus electrode and the end of the collector electrode section in the second electrode are respectively leaked from the first area, partial carriers in the second area cannot be timely led out due to the fact that one of the second distance and the third distance is larger can be prevented, and the back contact battery is ensured to have high photoelectric conversion efficiency.
As a possible implementation manner, in the second direction, the end portion of each current collecting electrode section in the first electrode is spaced from an adjacent bus electrode included in the second electrode by a fourth distance. In the second direction, the distance between the end of each current collecting electrode section in the second electrode and the adjacent bus electrode included in the first electrode is a fifth distance. The fourth distance is less than the fifth distance.
With the above technical solution, it can be understood that, in the first electrode and the second electrode, the adjacent two collector electrode segments included in the same collector electrode have a space for isolating the collector electrode with opposite polarity to itself, so as to inhibit electric leakage. Based on this, when the above-mentioned fourth distance is smaller than the fifth distance, the end portion of each collector electrode segment in the second electrode may be separated from the adjacent collector electrode included in the first electrode by the fifth distance having a larger length, so that it is ensured that the end portion of each collector electrode segment in the second direction in the second electrode does not overlap the first region opposite to the self-conductive type and the adjacent collector electrode included in the first electrode, and that the current leakage is prevented, and also, in the case of ensuring that the end portion of each collector electrode segment in the second direction in the first electrode does not overlap the second region opposite to the self-conductive type and the adjacent collector electrode included in the second electrode, the distance between the end portion of each collector electrode segment in the first electrode in the second direction and the second region is reduced to a greater extent, so that the carrier collecting capability of each collector electrode segment in the first electrode is improved. In other words, the back contact battery provided by the invention can respectively regulate and control the distance between the end part of each current collecting electrode section in the positive electrode and the adjacent bus electrode included in the negative electrode and the distance between the end part of each current collecting electrode section in the negative electrode and the adjacent bus electrode included in the positive electrode along the second direction according to the practical application scene, so that the back contact battery can prevent electric leakage, improve the electrical stability of the back contact battery, simultaneously enable the current collecting electrode sections to have relatively strong carrier collecting capability, and facilitate improving the photoelectric conversion efficiency of the back contact battery.
As a possible implementation, each region of each collector electrode segment in the first electrode along the second direction is in direct contact with the first region. In this case, under the same other factors, when the respective regions of each collector electrode segment in the second direction in the first electrode are in direct contact with the first region, the contact area between each collector electrode segment in the first electrode and the first region is larger, which is advantageous for reducing the contact resistance between each collector electrode segment in the first electrode and the first region, compared with the case that the partial region of each collector electrode segment in the second direction in the first electrode is in direct contact with the second region.
As a possible implementation, a partial region of each collector electrode segment in the first electrode in the second direction is in direct contact with the first region. In this case, under the same other factors, when the partial region of each collector electrode segment in the second direction in the first electrode is in direct contact with the second region, the contact area between each collector electrode segment in the first electrode and the second region is smaller, so that the contact area between the surface passivation layer and the first region is larger, and the passivation effect of the surface passivation layer on the first region can be improved, compared with the case that each region of each collector electrode segment in the second direction in the first electrode is in direct contact with the first region.
As a possible implementation, each bus electrode included in the first electrode is not in direct contact with the first region. In this case, the contact area between the first electrode and the first region is smaller when the first electrode includes the bus electrode that is not in direct contact with the first region, as compared with the case where the first electrode includes the bus electrode that is also in direct contact with the first region, under the same other factors. At this time, the contact area between the surface passivation layer and the first area is larger, so that the passivation effect of the surface passivation layer on the backlight surface side of the semiconductor substrate can be improved, and the working performance of the back contact battery can be improved.
As a possible implementation, each bus electrode included in the second electrode is not in direct contact with the second region. In this case, the contact area between the second electrode and the second region is smaller when the bus electrode included in the second electrode is not in direct contact with the second region, as compared with the bus electrode included in the second electrode is also in direct contact with the second region, under the same other factors. At this time, the contact area between the surface passivation layer and the second area is larger, so that the passivation effect of the surface passivation layer on the backlight surface side of the semiconductor substrate can be improved, and the working performance of the back contact battery can be improved.
As one possible implementation, the semiconductor substrate includes: the semiconductor device comprises a P-type semiconductor substrate and an N-type tunneling passivation contact structure formed on a partial region of a backlight surface of the P-type semiconductor substrate. The area of the backlight surface of the P-type semiconductor substrate exposed outside the N-type tunneling passivation contact structure is a first area, and the area of one side of the N-type tunneling passivation contact structure, which is away from the P-type semiconductor substrate, is a second area.
Under the condition of adopting the technical scheme, in the actual manufacturing process of the semiconductor substrate, the first area and the second area with opposite conductive types can be formed on one side of the backlight surface only by forming the N-type tunneling passivation contact structure on the part of the P-type semiconductor substrate corresponding to the second area, so that the problem that the manufacturing process of the back contact battery is complex due to the fact that the backlight surface is required to be doped with the conductive types twice. In addition, the N-type tunneling passivation contact structure has excellent interface passivation effect and selective collection of carriers, and can further improve the photoelectric conversion efficiency of the back contact battery.
In a second aspect, the present invention also provides a method for manufacturing a back contact battery, the method comprising: first, a semiconductor substrate is formed. The backlight surface of the semiconductor substrate has alternately distributed first and second regions. The first region and the second region are opposite in conductivity type. Then, a surface passivation layer is formed to cover the backlight surface. And a conductive window is arranged in the surface passivation layer, and part of the first area is exposed at the bottom of the conductive window. Next, a first electrode and a second electrode are formed on the backlight surface side. The projection of at least part of the first electrode on the backlight surface is positioned in the first area. The projection of the second electrode on the backlight surface is positioned in the second area. The first electrode and the second electrode each include a plurality of collector electrodes and a plurality of bus electrodes. The first electrode includes bus electrodes and the second electrode includes bus electrodes that extend in a first direction and are alternately spaced apart in a second direction, the first direction being different from the second direction. The collector electrodes included in the first electrode penetrate through the surface passivation layer through the conductive window and are in ohmic contact with the first area, the collector electrodes included in the second electrode penetrate through part of the surface passivation layer and are in ohmic contact with the second area, and the collector electrodes included in the first electrode and the collector electrodes included in the second electrode extend along the second direction and are alternately distributed at intervals along the first direction. Each collector electrode is connected with a collector electrode with the same polarity, and each collector electrode comprises a plurality of collector electrode sections which are distributed at intervals along the second direction, and the interval between every two adjacent collector electrode sections in the same collector electrode is used for isolating the collector electrode with the opposite polarity. Wherein a portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region. The end of each contact region is spaced apart from the edge of the first region by a first distance in the second direction. In the second direction, the end of each current collecting electrode section in the second electrode is spaced apart from the edge of the first region by a second distance. The first distance is less than the second distance.
The beneficial effects of the second aspect of the present invention may be referred to for analysis of beneficial effects in the first aspect and various implementation manners thereof, and will not be described here in detail.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
fig. 1 is a schematic diagram showing distribution positions of a first electrode and a second electrode included in a back contact battery in the related art;
fig. 2 is a schematic diagram of distribution positions of a first electrode and a second electrode, and an enlarged schematic diagram of corresponding positions of the first electrode and the second electrode, which are included in a back contact battery according to an embodiment of the present invention;
fig. 3 is a schematic longitudinal sectional view of a portion of the structure of a back contact battery at a second electrode according to an embodiment of the present invention;
fig. 4 is a schematic longitudinal sectional view of a portion of the structure of a back contact battery provided in an embodiment of the present invention at a first electrode.
Reference numerals: 11 is a first region, 12 is a second region, 13 is a first electrode, 14 is a second electrode, 15 is a collector electrode, 16 is a collector electrode, 17 is a collector electrode segment, 18 is a conductive window, L1 is a first distance, L2 is a second distance, L3 is a third distance, L4 is a fourth distance, L5 is a fifth distance, L6 is a sixth distance, and L7 is a seventh distance.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
Various structural schematic diagrams according to embodiments of the present disclosure are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and relative sizes, positional relationships between them shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.
In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present therebetween. In addition, if one layer/element is located "on" another layer/element in one orientation, that layer/element may be located "under" the other layer/element when the orientation is turned. In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. The meaning of "a number" is one or more than one unless specifically defined otherwise.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Currently, solar cells are increasingly used as new energy alternatives. Among them, a photovoltaic solar cell is a device that converts solar light energy into electric energy. Specifically, the solar cell generates carriers by utilizing the photovoltaic principle, and then the carriers are led out by using the electrodes, so that the electric energy can be effectively utilized.
When the positive electrode and the negative electrode of the solar cell are positioned on the backlight surface of the solar cell, the solar cell is a back contact cell. The light-directing surface of the back contact battery has no influence of shielding of the metal electrode, so that compared with a solar battery with shielding of the light-directing surface, the back contact battery has higher short-circuit current and photoelectric conversion efficiency, and is one of the technical directions for realizing the high-efficiency crystalline silicon battery at present. And, the back passivation layer is formed on the back surface side of the semiconductor substrate included in the back contact battery, so that the carrier recombination rate on the back surface side of the semiconductor substrate can be reduced, and the working performance of the back contact battery is improved.
Specifically, fig. 1 shows a schematic diagram of distribution positions of a first electrode and a second electrode included in a back contact battery in the related art. As shown in fig. 1, the back contact cell includes a first electrode 13 and a second electrode 14, which are opposite in conductivity type, each formed on the backlight side of the semiconductor substrate. In this regard, in an actual manufacturing process, a doped semiconductor layer is generally formed on a whole layer on a backlight side of a semiconductor substrate, and a portion of the doped semiconductor layer is removed by laser etching or the like, so as to form a semiconductor substrate in which a first region 11 and a second region (the conductivity types of the first region and the second region are opposite) are alternately distributed on the backlight side. Then, a surface passivation layer provided with a conductive window is formed on the backlight side of the semiconductor substrate. Next, as shown in fig. 1, the first electrode 13 and the second electrode 14 are formed on the backlight surface side by a process such as screen printing. Wherein the first electrode 13 and the second electrode 14 each include a plurality of collector electrodes 15 and a plurality of bus electrodes 16. The bus electrodes 16 included in the first electrode 13 and the bus electrodes 16 included in the second electrode 14 each extend in the first direction and are alternately spaced apart in the second direction (the second direction being different from the first direction). The collector electrode 15 included in the first electrode 13 is formed by using a non-firing through type electrode paste and is in ohmic contact with the first region 11 through a conductive window (not shown in the figure), the collector electrode 15 included in the second electrode 14 is formed by using a firing through type electrode paste and is in ohmic contact with the second region 12 through a firing through part of a surface passivation layer (not shown in the figure), and the collector electrodes 15 included in the first electrode 13 and the collector electrodes 15 included in the second electrode 14 are both extended in the second direction and are alternately spaced apart in the first direction. Each collector electrode 15 is connected with a collector electrode 16 with the same polarity, and each collector electrode 15 comprises a plurality of collector electrode segments 17 distributed at intervals along the second direction, and two adjacent collector electrode segments 17 in the same collector electrode 15 are provided with intervals for separating the collector electrode 16 with the opposite polarity to the collector electrode to prevent electric leakage.
Wherein, along the second direction, the interval between the end of each current collecting electrode section in the first electrode and the edge of the second area is a sixth distance. In the second direction, the end of each current collecting electrode section in the second electrode is spaced apart from the edge of the first region by a second distance. As shown in fig. 1, the sixth distance L6 in the conventional back contact cell is equal to the second distance L2. It will be appreciated that the portion of the first region 11 in ohmic contact with each collector electrode segment 17 of the first electrode 13 is the contact region. In the second direction, the end of each collector electrode segment 17 in the first electrode 13 is flush with the end of the contact region, or the end of each collector electrode segment 17 in the first electrode 13 is closer to the second region 12 than the end of the contact region. Based on this, when the sixth distance L6 is equal to the second distance L2, the minimum distance (first distance) between the end of each contact region and the edge of the second region 12 is equal to or greater than the second distance L2. In this case, since the collector electrode 15 in the first electrode 13 is a non-burn-through electrode, the conductive window limits the contact range between the non-burn-through electrode and the first region 11, so that the collector electrode 15 in the first electrode 13 does not contact with a portion of the backlight surface side of the semiconductor substrate, which is not exposed in the conductive window, and the second distance L2 is a safe distance between the burn-through electrode and the opposite doped region for preventing leakage, when the first distance is greater than or equal to the second distance L2, the free distance between the end of the contact region along the second direction and the edge of the second region 12 is greater, resulting in poor carrier collection capability of each collector electrode segment 17 included in the first electrode 13, and further resulting in a greater carrier recombination rate, which is unfavorable for improving the photoelectric conversion efficiency of the back contact battery.
In order to solve the technical problems described above, in a first aspect, an embodiment of the present invention provides a back contact battery. The back contact battery includes: the semiconductor device comprises a semiconductor substrate, a surface passivation layer, a first electrode and a second electrode. As shown in fig. 2, the backlight surface of the semiconductor substrate has first regions 11 and second regions 12 alternately distributed. The conductivity types of the first region 11 and the second region 12 are opposite. The surface passivation layer covers one side of the backlight surface. A conductive window 18 is provided in the surface passivation layer, and a bottom of the conductive window 18 exposes a portion of the first region 11. The first electrode 13 and the second electrode 14 are formed on the backlight side. The projection of at least part of the first electrode 13 onto the backlight is located within the first region 11. The projection of the second electrode 14 onto the backlight is located within the second region 12. Each of the first electrode 13 and the second electrode 14 includes a plurality of collector electrodes 15 and a plurality of bus electrodes 16. The bus electrodes 16 included in the first electrode 13 and the bus electrodes 16 included in the second electrode 14 each extend in a first direction and are alternately spaced apart in a second direction, the first direction being different from the second direction. The first electrode 13 includes a collector electrode 15 that is a non-burn-through electrode and is in ohmic contact with the first region 11 through a conductive window 18. The collector electrode 15 included in the second electrode 14 is a burn-through electrode, and a part of the surface passivation layer is burned through and in ohmic contact with the second region 12, and the collector electrode 15 included in the first electrode 13 and the collector electrode 15 included in the second electrode 14 each extend in the second direction and are alternately spaced apart in the first direction. Each collector electrode 15 is connected to a collector electrode 16 of the same polarity as itself, and each collector electrode 15 includes a plurality of collector electrode segments 17 spaced apart in the second direction, and adjacent two collector electrode segments 17 in the same collector electrode 15 have a spacing for separating the collector electrode 16 of the opposite polarity from itself. Wherein the portion of the first region 11 in ohmic contact with each collector electrode segment 17 of the first electrode 13 is the contact region. In the second direction, the minimum distance between the end of each contact region and the edge of the second region 12 is the first distance L1. In the second direction, the end of each collector electrode segment 17 in the second electrode 14 is spaced a second distance L2 from the edge of the first region 11. The first distance L1 is smaller than the second distance L2.
It should be noted that, fig. 2 is only for convenience to show the relative positional relationship between the first area and the second area and the first electrode and the second electrode, and the specific range of the conductive window, and the corresponding structure is shown by perspective, and in practical application, the first area, the second area and the conductive window cannot be directly observed from the viewing angle.
Specifically, the structure and the material of the semiconductor substrate and the conductivity types of the first region and the second region in the embodiment of the present invention are not particularly limited, so long as the embodiment of the present invention can be applied to the back contact battery provided in the embodiment of the present invention.
Illustratively, the above semiconductor substrate may include: a semiconductor substrate, and a doped semiconductor layer formed on a partial region of a backlight surface of the semiconductor substrate. The area of the backlight surface of the semiconductor substrate exposed outside the doped semiconductor layer is a first area, and the area of one side of the doped semiconductor layer, which is away from the semiconductor substrate, is a second area. Secondly, the conductivity types of the doped semiconductor layer and the semiconductor substrate can be the same, and the semiconductor base further comprises a second doped semiconductor layer which is opposite to the conductivity type of the semiconductor substrate and is formed on a part of the surface of the semiconductor substrate corresponding to the first region; alternatively, the doped semiconductor layer may also be of opposite conductivity type to the semiconductor substrate. It should be noted that when the conductivity types of the doped semiconductor layer and the semiconductor substrate are opposite, in the actual process of manufacturing the semiconductor substrate, only a whole doped semiconductor layer covering the backlight surface of the semiconductor substrate is required to be formed, and part of the doped semiconductor layer is removed, so that the first region and the second region with opposite conductivity types can be formed on one side of the backlight surface, thereby solving the problem that the manufacturing flow of the back contact battery is complex due to the need of carrying out two times of doping with opposite conductivity types on the backlight surface.
Specifically, in terms of conductivity type, the semiconductor substrate may be an N-type semiconductor substrate, and if the conductivity types of the doped semiconductor layer and the N-type semiconductor substrate are the same, the doped semiconductor layer is an N-type doped semiconductor layer, the first region is a P-type region, and the second region is an N-type region; if the conductivity types of the doped semiconductor layer and the N-type semiconductor substrate are opposite, the doped semiconductor layer is a P-type doped semiconductor layer, the first area is an N-type area, and the second area is a P-type area;
alternatively, the semiconductor substrate may be a P-type semiconductor substrate, and if the conductivity types of the doped semiconductor layer and the N-type semiconductor substrate are the same, the doped semiconductor layer is a P-type doped semiconductor layer, the first region is an N-type region, and the second region is a P-type region; if the conductivity types of the doped semiconductor layer and the P-type semiconductor substrate are opposite, the doped semiconductor layer is an N-type doped semiconductor layer, the first region is a P-type region, and the second region is an N-type region.
It is noted that aluminum materials are commonly used materials for manufacturing positive electrodes in back contact cells to reduce contact resistance by forming an alloy layer of aluminum with the corresponding semiconductor material. Also, most of the electrode paste including aluminum is a non-burn-through type electrode paste. While silver material is a common material for manufacturing negative electrodes in back contact cells, and electrode paste in which part of the material includes silver is burn-through electrode paste. Based on this, when the conductivity type of the first region is P-type and the conductivity type of the second region is N-type, the collector electrode included in the first electrode may be manufactured at least by using an aluminum material, and the collector electrode included in the second electrode may be manufactured at least by using an aluminum material, so that the manufacturing difficulty of the first electrode and the second electrode is reduced, and meanwhile, the application range of the back contact battery provided by the embodiment of the present invention may be further enlarged.
In terms of materials, the material of the semiconductor substrate may include any semiconductor material such as silicon, silicon germanium, germanium or gallium arsenide. As for the above-mentioned doped semiconductor layer, the material of the doped semiconductor layer may include any semiconductor material such as silicon, silicon germanium, silicon carbide, or gallium arsenide. The doped semiconductor layer may be amorphous, microcrystalline, single crystal, nanocrystalline, polycrystalline, or the like in terms of the internal arrangement form of the substance.
In some cases, the semiconductor base may further include a passivation layer between the semiconductor substrate and the doped semiconductor layer. The passivation layer can passivate at least a portion of the surface of the semiconductor substrate in contact with the doped semiconductor layer, reducing the rate at which carriers recombine at the contact of the two. And the doped semiconductor layer formed on the passivation layer can realize selective collection of carriers of corresponding conductivity types in the semiconductor substrate, so that the photoelectric conversion efficiency of the back contact battery provided by the embodiment of the invention is further improved. In particular, the material of the passivation layer may be determined according to the material of the doped semiconductor layer.
For example: when the doped semiconductor layer is a doped amorphous silicon layer, a doped microcrystalline silicon layer, or a mixed layer of doped amorphous silicon and microcrystalline silicon, the passivation layer may be an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, or a mixed layer of intrinsic amorphous silicon and microcrystalline silicon. At this time, the doped semiconductor layer and the passivation layer may constitute a hetero-contact structure.
Also for example: when the doped semiconductor layer is a doped polysilicon layer, the passivation layer is a tunneling passivation layer. At this time, the doped semiconductor layer and the passivation layer may constitute a tunneling passivation contact structure. In addition, the material of the tunneling passivation layer may include any dielectric material having a tunneling passivation effect. For example: the material of the tunnel passivation layer may include one or more of silicon oxide, aluminum oxide, titanium oxide, hafnium oxide, gallium oxide, tantalum pentoxide, niobium pentoxide, silicon nitride, silicon carbonitride, aluminum nitride, titanium carbonitride.
When the semiconductor substrate included in the semiconductor base is a P-type semiconductor substrate, the doped semiconductor layer is an N-type doped polysilicon layer, and a tunneling passivation layer is formed between the P-type semiconductor substrate and the N-type doped polysilicon layer, the back contact battery provided by the embodiment of the invention is an HPBC (hybrid passivation back contact) battery. The tunneling passivation layer and the N-type doped polysilicon layer form an N-type tunneling passivation contact structure.
For the surface passivation layer, the material and thickness of the surface passivation layer may be determined according to practical requirements, so long as the surface passivation layer can be applied to the back contact battery provided by the embodiment of the invention. For example: the material of the surface passivation layer may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, and silicon carbide.
As for the first electrode and the second electrode, the material of the first electrode or the second electrode may include a conductive material such as silver, aluminum, copper, titanium, or nickel, so long as the collector electrode included in the first electrode is a non-burn-through electrode and the collector electrode included in the second electrode is a burn-through electrode. The materials of the first electrode and the second electrode may be the same or different.
Notably, aluminum and silver are commonly used electrode fabrication materials for back contact cells. When the material of the collector electrode included in the first electrode includes aluminum and the material of the collector electrode included in the second electrode includes silver, manufacturing difficulty of the first electrode and the second electrode can be reduced, and meanwhile the application range of the back contact battery provided by the embodiment of the invention can be enlarged.
In terms of polarity, since the collector electrode included in the first electrode is in ohmic contact with the first region and the collector electrode included in the second electrode is in ohmic contact with the second region, the polarities of the first electrode and the second electrode may be determined according to the conductivity types of the first region and the second region, respectively.
For example: when the first region is an N-type region and the second region is a P-type region, the first electrode is a negative electrode and the second electrode is a positive electrode.
Also for example: when the first region is a P-type region and the second region is an N-type region, the first electrode is a positive electrode and the second electrode is a negative electrode.
It is understood that one collector electrode included in the positive electrode is opposite in polarity to one collector electrode included in the negative electrode (or one collector electrode included in the negative electrode), and is the same in polarity as the other collector electrode included in the positive electrode (or one collector electrode included in the positive electrode). Similarly, one of the bus electrodes included in the positive electrode has a polarity opposite to that of one of the collector electrodes included in the negative electrode (or one of the collector electrodes included in the negative electrode), and is the same as that of the other of the collector electrodes included in the positive electrode (or one of the collector electrodes included in the positive electrode). Accordingly, the same or opposite polarity electrodes as the collector electrode and the bus electrode included in the negative electrode, respectively, may be referred to as the foregoing, and will not be described herein.
In terms of morphology, the bus electrodes included in the first electrode and the second electrode may be linear bus electrodes, wavy linear bus electrodes, zigzag bus electrodes, or the like. The specific shape of the bus electrode included in the first electrode and the second electrode may be set according to an actual application scenario, and is not particularly limited herein. In addition, the collector electrodes included in the first electrode and the second electrode may be linear collector electrodes, wavy linear collector electrodes, zigzag collector electrodes, or the like, and the specific shape of the collector electrodes included in the first electrode and the second electrode may be set according to the actual application scenario, and is not specifically limited herein.
As for the first direction and the second direction, they may be any two directions which are parallel to the backlight surface and are different from each other. Preferably, the first direction is orthogonal to the second direction.
In terms of electrical coupling, each region of each collector electrode segment in the first electrode along the second direction may be in direct contact with the first region. Alternatively, as shown in fig. 2 and 3, a partial region of each collector electrode segment 17 in the second direction in the first electrode 13 is in direct contact with the first region 11.
It should be noted that, under the same other factors, when the regions of each collector electrode segment in the second direction of the first electrode are in direct contact with the first region, the contact area between each collector electrode segment in the first electrode and the first region is larger, which is beneficial to reducing the contact resistance between each collector electrode segment in the first electrode and the first region, compared with the case that the partial region of each collector electrode segment in the second direction of the first electrode is in direct contact with the second region. Compared with the fact that each area of each collector electrode section in the first electrode along the second direction is directly contacted with the first area, when the partial area of each collector electrode section in the first electrode along the second direction is directly contacted with the second area, the contact area between each collector electrode section in the first electrode and the second area is smaller, the contact area between the surface passivation layer and the first area is larger, and the passivation effect of the surface passivation layer on the first area can be improved. Under the above circumstances, the contact range between each current collecting electrode segment in the first electrode and the first area can be determined according to the passivation effect of the surface passivation layer and the contact resistance requirement of the first electrode in the actual application scenario.
In the case where a partial region of each collector electrode segment in the first electrode in the second direction is in direct contact with the first region, the end of each collector electrode segment in the first electrode may be flush with the end of the corresponding contact region in the second direction. In this case, along the second direction, the actual manufacturing length of each collector electrode segment in the first electrode is approximately the same as the length for effectively collecting carriers (i.e., the distance between the two ends of the corresponding contact region along the second direction), so that the consumption of consumables of each collector electrode segment in the first electrode can be reduced, which is beneficial to reducing the manufacturing cost of the back contact battery.
Alternatively, in the case where a partial region of each collector electrode segment in the first electrode in the second direction is in direct contact with the first region, it is also possible that an end of each collector electrode segment in the first electrode is located between an end of the contact region and an edge of the second region or above the second region in the second direction. In this case, the actual manufacturing length of each collector electrode segment in the first electrode may be greater than the length of the effective collection carrier in the second direction. At this time, even if the end of each collector electrode segment in the first electrode in the second direction passes over the boundary between the first region and the second region and is located above the second region opposite to the conductivity type of the first electrode, the two can be isolated by the surface passivation layer, and higher manufacturing precision is not strictly required for manufacturing each collector electrode segment included in the first electrode with the end flush with the end of the corresponding contact region, so that the manufacturing difficulty of the back contact battery is reduced. In particular, in this case, the specific length by which the end portion of each collector electrode segment in the first electrode in the second direction extends than the end portion of the corresponding contact region may be determined according to the actual application scenario, and is not particularly limited herein.
And in the case where each region of each collector electrode segment in the first electrode in the second direction is in direct contact with the first region, the end of each collector electrode segment in the first electrode is flush with the end of the corresponding contact region in the second direction.
It will be appreciated that when the end of each collector electrode segment in the first electrode is flush with the end of the corresponding contact region, or the end of each collector electrode segment in the first electrode is located between the end of the contact region and the edge of the second region, in the second direction, the projections of the respective portions of the first electrode are all located within the first region. And when the end of each collector electrode segment in the first electrode is located above the second region in the second direction, the projection of the end of each collector electrode segment in the first electrode in the second direction is located within the second region, and the projection of the remaining portion of the second electrode is located within the first region.
As for the collector electrode included in the second electrode, since the collector electrode included in the second electrode is a burn-through electrode, each region of the collector electrode included in the second electrode along the second direction is in direct contact with the first region.
As for the bus electrode included in the first electrode and the bus electrode included in the second electrode, each of the bus electrodes included in the first electrode may be in direct contact with the first region. At this time, the contact area between the first electrode and the first region is larger, which is beneficial to reducing the contact resistance between the first electrode and the first region. Alternatively, each bus electrode included in the first electrode may not be in direct contact with the first region. In this case, the bus electrode included in the first electrode is isolated from the first region by the surface passivation layer, and each bus electrode included in the first electrode is electrically coupled with the first region by a corresponding collector electrode segment included in the first electrode. At this time, the contact area between the surface passivation layer and the first area is larger, which is beneficial to improving the passivation effect of the surface passivation layer on the first area.
In addition, each of the bus electrodes included in the second electrode may be in direct contact with the second region. At this time, the contact area between the second electrode and the second region is larger, which is beneficial to reducing the contact resistance between the second electrode and the second region. Alternatively, each bus electrode included in the second electrode may not be in direct contact with the second region. In this case, the bus electrode included in the second electrode is isolated from the second region by the surface passivation layer, and each bus electrode included in the second electrode is electrically coupled to the second region by a corresponding collector electrode segment included in the second electrode. Under the above circumstances, when other factors are the same, compared with the case that the bus electrode included in the second electrode is also in direct contact with the second region, when the bus electrode included in the second electrode is not in direct contact with the second region, the contact area between the second electrode and the second region is smaller, and the contact area between the surface passivation layer and the second region is larger, so that the passivation effect of the surface passivation layer on the backlight side of the semiconductor substrate can be improved, and the working performance of the back contact battery can be improved.
In terms of number and size, the number and specification of the collector electrodes and the bus electrodes included in the first electrode and the second electrode, the gaps between the collector electrodes included in the first electrode and the adjacent collector electrodes included in the second electrode along the first direction, and the gaps between the bus electrodes included in the first electrode and the adjacent collector electrodes included in the second electrode along the second direction may be set according to practical application scenarios, so long as the method can be applied to the back contact battery provided in the embodiment of the present invention. In practical applications, the number of bus electrodes included in the first electrode and the second electrode may be the same or different. The number of collector electrodes included in each of the first electrode and the second electrode may be the same or different. Further, in the first electrode, the number of collector electrode segments included in each collector electrode may be determined according to the number of bus electrodes included in the second electrode. In the second electrode, the number of collector electrode segments included in each collector electrode may be determined according to the number of collector electrodes included in the first electrode.
The size of the minimum distance (first distance) between the end of each contact region and the edge of the second region, and the size of the distance (i.e., second distance) between the end of each collector electrode segment in the second electrode and the edge of the first region can be determined according to practical requirements, so long as the first distance is smaller than the second distance, and the method can be applied to the back contact battery provided by the embodiment of the invention.
Under the condition of adopting the technical scheme, the collector electrode included in the first electrode is in ohmic contact with the first area through the conductive window formed in the surface passivation layer, and the collector electrode is used for collecting carriers of corresponding conductivity type in the first area and conducting the carriers to the collector electrode included in the first electrode. The second electrode includes a collector electrode that burns through a portion of the surface passivation layer and is in ohmic contact with the second region for collecting carriers of a corresponding conductivity type in the second region and conducting to a collector electrode included in the second electrode. Because of this, the first and second regions alternately arranged on the backlight side of the semiconductor substrate are opposite in conductivity type, so are the first and second electrodes. Meanwhile, a portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region. In the above case, as shown in fig. 2 to 4, the minimum distance (i.e., the first distance L1) between the end of each contact region and the edge of the second region 12 serves to isolate the first electrode 13 of opposite conductivity type from the second region 12, and the distance (i.e., the second distance L2) between the end of each collector electrode segment 17 of the second electrode 14 and the edge of the first region 11 serves to isolate the second electrode 14 of opposite conductivity type from the first region 11 in the second direction, preventing leakage and ensuring high electrical stability of the back contact cell.
Next, as shown in fig. 2 and 3, since each collector electrode 15 included in the first electrode 13 is a non-burn-through electrode and the surface passivation layer is a non-conductive insulating material layer, the conductive window 18 provided in the surface passivation layer determines the contact range between each collector electrode 15 in the first electrode 13 and the first region 11. In other words, in the process of actually manufacturing the back contact battery provided in the embodiment of the present invention, after the surface passivation layer provided with the conductive window 18 is formed, when each collector electrode 15 included in the first electrode 13 is manufactured by the non-burn-through electrode paste, the non-burn-through electrode paste can only contact a portion of the first region 11 through the conductive window 18, which cannot penetrate the portion of the surface passivation layer where the conductive window 18 is not provided. And each of the collector electrodes 15 included in the second electrode 14 is a burn-through electrode, and burns through a part of the surface passivation layer and makes ohmic contact with the second region 12. In other words, in the actual manufacturing process of the back contact battery provided in the embodiment of the present invention, the burn-through electrode for manufacturing each current collector included in the second electrode 14 may penetrate the surface passivation layer, so as to achieve electrical coupling with the region of the semiconductor substrate located under the burned-through portion of the surface passivation layer. In the above case, it is necessary to set the distance between the end of each collector electrode segment 17 in the second electrode 14 and the edge of the first region 11 to be a relatively large second distance L2 in the second direction to prevent the end of each collector electrode segment 17 in the second electrode 14 in the second direction from being overlapped to the first region 11 to generate electric leakage. However, since the surface passivation layer is a non-conductive film layer, the minimum distance between the end of the contact region where each collector electrode segment 17 in the first electrode 13 is in ohmic contact with the first region 11 and the edge of the second region 12 can be set to be a relatively small first distance L1, the space between the end of the contact region along the second direction and the edge of the second region 12 can be reduced, and the carrier collection capability of each collector electrode segment 17 included in the first electrode 13 is improved, so that the problem that the carrier recombination rate is high due to the fact that the carrier of the corresponding conductivity type at the space is difficult to be conducted out in time due to the fact that the first distance L1 is set to be equal to the second distance L2 in the prior art can be solved, and the photoelectric conversion efficiency of the back contact battery can be improved.
In the practical application process, as shown in fig. 2 to 4, the minimum distance between the edge of the bus electrode 16 and the edge of the first region 11 in the second electrode 14 along the second direction is the third distance L3. In the second direction, the end of each collector electrode segment 17 in the first electrode 13 is spaced from the adjacent bus electrode 16 included in the second electrode 14 by a fourth distance L4. In the second direction, the end of each collector electrode segment 17 in the second electrode 14 is spaced apart from the adjacent bus electrode 16 comprised by the first electrode 13 by a fifth distance L5. In the second direction, the minimum distance between the edge of the bus electrode 16 in the first electrode 13 and the edge of the first region 11 is the seventh distance L7. It will be appreciated that the fourth distance L4 is equal to the sum of the first distance L1 and the third distance L3, and the fifth distance L5 is equal to the sum of the second distance L2 and the seventh distance L7.
Wherein for the second distance, as shown in fig. 2 and 4, since each collector electrode 15 included in the second electrode 14 is in ohmic contact with the second region 12 and the conductivity type of the first region 11 is opposite to that of the second region 12, the magnitude of the second distance L2 affects whether or not a leakage occurs between the end of each collector electrode segment 17 in the second electrode 14 in the second direction and the edge of the first region 11 and affects the carrier collection of the corresponding portion of the second region 12 by each collector electrode segment 17 in the second electrode 14. Based on this, the magnitude of the second distance L2 can be determined according to the actual application scenario with respect to the requirements of the anticreep and carrier collection capability of each of the collector electrodes 15 included in the second electrode 14 as a burn-through electrode.
Illustratively, the second distance may be greater than 0 and less than 0.4mm. For example: the second distance may be 0.1mm, 0.2mm, 0.3mm, 0.4mm, etc. In this case, the second distance is within the above-described range, and it is possible to prevent the leakage preventing effect between the end of each collector electrode segment in the second electrode in the second direction and the edge of the first region from being poor due to the small second distance, ensuring high electrical stability of the back contact battery. In addition, carriers of the corresponding conductivity type generated near the edge of the second region can be prevented from being difficult to collect at the end of each collector electrode segment in the second electrode along the second direction due to the large second distance, so that the higher carrier collecting capability of each collector electrode segment in the second electrode is ensured, and further the higher photoelectric conversion efficiency of the back contact battery is ensured.
As for the first distance, it may be any value of 0 or more and less than the second distance. For example: when the second distance is equal to 0.3mm, the first distance may be equal to or greater than 0 and less than 0.3mm.
Preferably, the first distance is 0. In this case, in the second direction, the end of the respective contact region corresponding to each collector electrode segment in the first electrode is aligned with the edge of the second region. In other words, the free distance between the end of the contact region along the second direction and the edge of the second region is 0, so that the effective carrier collection length corresponding to each collector electrode segment in the first electrode can be maximized, the corresponding conductive type carriers generated by the part of the first region corresponding to each collector electrode segment in the first electrode can be ensured to be collected and exported, the carrier recombination rate is further reduced, and the photoelectric conversion efficiency of the back contact battery is improved.
As for the third distance, in an actual manufacturing process, the slurry state of the second electrode may affect the width of the bus electrode included in the formed second electrode, and the stage accuracy of manufacturing the second electrode may affect the position offset of the bus electrode included in the formed second electrode, so the third distance may also affect whether the bus electrode included in the second electrode is overlapped. Based on this, the magnitude of the above-mentioned third distance may be determined according to an actual manufacturing process, and is not particularly limited herein.
Illustratively, the ratio of the third distance to the second distance is greater than or equal to 0.8 and less than or equal to 1.2. In this case, the above-mentioned second distance and third distance are pitches of the end portion of the collector electrode segment and the edge of the bus electrode in the second direction, respectively, from the edge of the first region opposite in conductivity type to itself, respectively. Based on this, in the actual manufacturing process, the second distance and the third distance need to take into account machining errors of the bus electrode and the collector electrode segment in the second electrode, respectively, so that corresponding intervals are reserved to prevent the edges of the bus electrode and the ends of the collector electrode segment in the second electrode from overlapping to the first region with opposite conductivity types. The machining errors of the bus electrode and the collector electrode section included in the second electrode are approximately the same, so that when the ratio of the second distance to the third distance is more than or equal to 0.8 and less than or equal to 1.2, the two are approximately equal, and on the premise that the edge of the bus electrode and the end of the collector electrode section in the second electrode are respectively leaked from the first area, partial carriers in the second area cannot be timely led out due to the fact that one of the second distance and the third distance is larger can be prevented, and the back contact battery is ensured to have high photoelectric conversion efficiency.
It is understood that when the back contact cell includes different specifications of the semiconductor substrate, the requirements for the anticreep and carrier collection capabilities of the first electrode and the second electrode may also be different. In addition, the accuracy of the first electrode and the second electrode manufactured by different machine stations or different slurries may be different, so the third distance may be determined according to the specification of the semiconductor substrate in the practical application scenario and the practical manufacturing process.
For example: the absolute value of the difference between the second distance and the third distance may be 0 or more and 300 μm or less.
For example: the third distance may be greater than 0 and equal to or less than 3mm.
Next, it is understood that, among the first electrode and the second electrode, the same collector electrode includes adjacent two collector electrode segments having a space for isolating the collector electrode having the opposite polarity to itself, suppressing leakage. Based on the above, the fourth distance and the fifth distance can be determined according to the anti-creeping requirement of the actual application scene on the collector electrode and the bus electrode with opposite polarity.
Illustratively, the fourth distance is less than the fifth distance. In this case, the end portion of each collector electrode segment in the second electrode may be separated from the adjacent collector electrode included in the first electrode by a fifth distance having a larger length, so that it is ensured that the end portion of each collector electrode segment in the second direction of the second electrode does not overlap the first region opposite to the self-conductive type and the adjacent collector electrode included in the first electrode, and thus, while preventing leakage, it is also possible to reduce the distance between the end portion of each collector electrode segment in the second direction of the first electrode and the second region to a greater extent and improve the carrier collecting capability of each collector electrode segment in the first electrode, while ensuring that the end portion of each collector electrode segment in the second direction of the first electrode does not overlap the second region opposite to the self-conductive type and the adjacent collector electrode included in the second electrode. In other words, according to the back contact battery provided by the embodiment of the invention, the distance between the end part of each current collecting electrode section in the positive electrode and the adjacent bus electrode included in the negative electrode and the distance between the end part of each current collecting electrode section in the negative electrode and the adjacent bus electrode included in the positive electrode can be independently regulated and controlled according to the practical application scene, so that the electric stability of the back contact battery can be improved while the electric leakage is prevented, the current collecting electrode sections have relatively strong carrier collecting capability, and the photoelectric conversion efficiency of the back contact battery can be improved.
As for the seventh distance, it may be determined according to the magnitudes of the above-described fifth distance and second distance. Illustratively, the seventh distance may be 0.07mm or more and less than 0.15mm. For example: the seventh distance may be 0.07mm, 0.09mm, 0.11mm, 0.13mm, 0.14mm, or the like. In this case, the seventh distance is within the above-described range, and it is possible to prevent the part of the bus electrode included in the actually formed first electrode from being located above the second region due to the small machining allowance left due to the small seventh distance, ensuring that the overlap leakage problem of the bus electrode included in the first electrode can be prevented by the seventh distance. Meanwhile, the manufacturing precision of the bus electrode in the first electrode is also prevented from being strictly required to avoid electric leakage, and the manufacturing difficulty of the bus electrode in the first electrode is reduced. In addition, the range of the second area which is positioned on the side of the backlight surface together with the first area is prevented from being smaller due to the fact that the seventh distance is larger, the carrier recombination rate on the side of the backlight surface is reduced, and the photoelectric conversion efficiency of the back contact battery is improved.
In a second aspect, an embodiment of the present invention further provides a method for manufacturing a back contact battery, where the method for manufacturing a back contact battery includes the following steps:
First, a semiconductor substrate is formed. The backlight surface of the semiconductor substrate has alternately distributed first and second regions. The first region and the second region are opposite in conductivity type.
In particular, the specific structure and materials of the above semiconductor substrate may be referred to the foregoing, and will not be described herein. As for the formation process of the semiconductor substrate, it may be determined according to the specific structure of the semiconductor substrate.
For example, when the semiconductor base includes a P-type semiconductor substrate, and a tunneling passivation layer and an N-type doped polysilicon layer stacked on a partial region disposed on a side of a back light surface of the P-type semiconductor substrate, the tunneling passivation layer and the N-type doped polysilicon layer may be formed to entirely cover the side of the back light surface of the P-type semiconductor substrate by a chemical vapor deposition process or the like. And then, removing the tunneling passivation layer and the part of the N-type doped polysilicon layer, which are arranged in a stacked manner, and are positioned on the first area corresponding to the P-type semiconductor substrate by adopting processes such as laser etching and the like, so as to obtain a semiconductor substrate.
Then, a surface passivation layer is formed to cover the backlight surface. And a conductive window is arranged in the surface passivation layer, and part of the first area is exposed at the bottom of the conductive window.
Specifically, the material and thickness of the surface passivation layer may be referred to above, and will not be described herein. In the actual manufacturing process, a chemical vapor deposition process and other processes can be adopted to form a surface passivation layer which covers one side of the backlight surface of the semiconductor substrate, and then a laser etching process and other processes are adopted to form a conductive window penetrating through the surface passivation layer. Alternatively, a mask layer may be formed at a position corresponding to the conductive window by using a photolithography process or the like. Then, a surface passivation layer with a conductive window is directly formed by adopting a chemical vapor deposition process and the like. Then, the mask layer is removed.
Next, a first electrode and a second electrode are formed on the backlight surface side. As shown in fig. 2 to 4, the projection of at least part of the first electrode 13 onto the backlight surface is located in the first region 11. The projection of the second electrode 14 onto the backlight is located within the second region 12. Each of the first electrode 13 and the second electrode 14 includes a plurality of collector electrodes 15 and a plurality of bus electrodes 16. The bus electrodes 16 included in the first electrode 13 and the bus electrodes 16 included in the second electrode 14 each extend in a first direction and are alternately spaced apart in a second direction, the first direction being different from the second direction. The collector electrode 15 included in the first electrode 13 penetrates through the surface passivation layer through the conductive window 18 and is in ohmic contact with the first region 11, the collector electrode 15 included in the second electrode 14 penetrates through a part of the surface passivation layer and is in ohmic contact with the second region 12, and the collector electrode 15 included in the first electrode 13 and the collector electrode 15 included in the second electrode 14 both extend in the second direction and are alternately distributed at intervals along the first direction. Each collector electrode 15 is connected to a collector electrode 16 of the same polarity as itself, and each collector electrode 15 includes a plurality of collector electrode segments 17 spaced apart in the second direction, and adjacent two collector electrode segments 17 in the same collector electrode 15 have a spacing for separating the collector electrode 16 of the opposite polarity from itself. Wherein the portion of the first region 11 in ohmic contact with each collector electrode segment 17 of the first electrode 13 is the contact region. In the second direction, the end of each contact region is spaced apart from the edge of the first region 11 by a first distance L1. In the second direction, the end of each collector electrode segment 17 in the second electrode 14 is spaced a second distance L2 from the edge of the first region 11. The first distance L1 is smaller than the second distance L2.
In particular, the specific structures of the first electrode and the second electrode, and the magnitudes of the first distance and the second distance may be referred to the foregoing, and will not be described herein. Next, in an actual manufacturing process, the first electrode and the second electrode may be formed using a screen printing process or the like. The first electrode comprises a collector electrode which is manufactured by adopting non-burning-through electrode slurry, and the second electrode comprises a collector electrode which is manufactured by adopting burning-through electrode slurry.
The beneficial effects of the second aspect of the embodiments of the present invention may refer to the beneficial effect analysis in the first aspect and various implementation manners thereof, which are not described herein.
In the above description, technical details of patterning, etching, and the like of each layer are not described in detail. Those skilled in the art will appreciate that layers, regions, etc. of the desired shape may be formed by a variety of techniques. In addition, to form the same structure, those skilled in the art can also devise methods that are not exactly the same as those described above. In addition, although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A back contact battery, comprising:
a semiconductor substrate, wherein a backlight surface of the semiconductor substrate is provided with a first area and a second area which are alternately distributed; the first region and the second region are opposite in conductivity type;
a surface passivation layer covering one side of the backlight surface; a conductive window is arranged in the surface passivation layer, and part of the first area is exposed out of the bottom of the conductive window;
a first electrode and a second electrode formed on one side of the backlight surface; the projection of at least part of the first electrode on the backlight surface is positioned in the first area; the projection of the second electrode on the backlight surface is positioned in the second area; the first electrode and the second electrode each include a plurality of collector electrodes and a plurality of bus electrodes; the first electrode comprises bus electrodes and the second electrode comprises bus electrodes which extend along a first direction and are alternately distributed at intervals along a second direction, and the first direction is different from the second direction; the collector electrode of the first electrode is a non-burn-through electrode and is in ohmic contact with the first region through the conductive window; the collector electrode included in the second electrode is a burn-through electrode, part of the surface passivation layer is burnt through and in ohmic contact with the second area, and the collector electrode included in the first electrode and the collector electrode included in the second electrode extend along the second direction and are alternately distributed at intervals along the first direction; each collector electrode is connected with the collector electrode with the same polarity, and each collector electrode comprises a plurality of collector electrode sections which are distributed at intervals along the second direction, and the interval between two adjacent collector electrode sections in the same collector electrode is used for isolating the collector electrode with the opposite polarity; wherein,
A part of the first region, which is in ohmic contact with each current collecting electrode section in the first electrode, is a contact region; the minimum distance between the end of each contact area and the edge of the second area is a first distance along the second direction; a distance between the end of each current collecting electrode section in the second electrode and the edge of the first region is a second distance along the second direction; the first distance is less than the second distance.
2. The back contact battery of claim 1, wherein in the second direction, an end of each collector electrode segment in the first electrode is flush with an end of the respective contact region;
or alternatively, the first and second heat exchangers may be,
in the second direction, an end of each of the collector electrode segments in the first electrode is located between an end of the contact region and an edge of the second region or above the second region.
3. The back contact battery of claim 1, wherein the first distance is 0;
and/or the number of the groups of groups,
the second distance is greater than 0 and less than 0.4mm.
4. The back contact battery of claim 1, wherein the first region has a P-type conductivity and the second region has an N-type conductivity;
And/or the number of the groups of groups,
the first electrode comprises a collector electrode material comprising aluminum, and the second electrode comprises a collector electrode material comprising silver.
5. The back contact battery of any one of claims 1-4, wherein a minimum distance between an edge of a bus electrode in the second electrode and an edge of the first region in the second direction is a third distance; the ratio of the third distance to the second distance is greater than or equal to 0.8 and less than or equal to 1.2.
6. The back contact battery of any one of claims 1-4, wherein an end of each collector electrode segment in the first electrode is a fourth distance from an adjacent one of the collector electrodes comprised by the second electrode in the second direction; a fifth distance is formed between the end part of each current collecting electrode section in the second electrode and the adjacent bus electrode included in the first electrode along the second direction; the fourth distance is less than the fifth distance.
7. The back contact battery of any one of claims 1-4, wherein each region of each collector electrode segment in the first electrode along the second direction is in direct contact with the first region;
Or alternatively, the first and second heat exchangers may be,
a partial region of each collector electrode segment in the first electrode along the second direction is in direct contact with the first region.
8. The back contact battery of any one of claims 1-4, wherein each bus electrode comprised by the first electrode is not in direct contact with the first region;
and/or the number of the groups of groups,
each bus electrode included in the second electrode is not in direct contact with the second region.
9. The back contact battery of claim 8, wherein the semiconductor substrate comprises: a P-type semiconductor substrate, and an N-type tunneling passivation contact structure formed on a partial region of a backlight surface of the P-type semiconductor substrate;
the area of the backlight surface of the P-type semiconductor substrate exposed outside the N-type tunneling passivation contact structure is the first area, and the area of one side of the N-type tunneling passivation contact structure, which is away from the P-type semiconductor substrate, is the second area.
10. A method of manufacturing a back contact battery, comprising:
forming a semiconductor substrate; the backlight surface of the semiconductor substrate is provided with first areas and second areas which are alternately distributed; the first region and the second region are opposite in conductivity type;
Forming a surface passivation layer covering the backlight surface; a conductive window is arranged in the surface passivation layer, and part of the first area is exposed out of the bottom of the conductive window;
forming a first electrode and a second electrode on one side of the backlight surface; the projection of at least part of the first electrode on the backlight surface is positioned in the first area; the projection of the second electrode on the backlight surface is positioned in the second area; the first electrode and the second electrode each include a plurality of collector electrodes and a plurality of bus electrodes; the first electrode comprises bus electrodes and the second electrode comprises bus electrodes which extend along a first direction and are alternately distributed at intervals along a second direction, and the first direction is different from the second direction; the collector electrode included in the first electrode penetrates through the surface passivation layer through the conductive window and is in ohmic contact with the first area, the collector electrode included in the second electrode penetrates through part of the surface passivation layer and is in ohmic contact with the second area, and the collector electrodes included in the first electrode and the collector electrodes included in the second electrode extend along the second direction and are alternately distributed at intervals along the first direction; each collector electrode is connected with the collector electrode with the same polarity, and each collector electrode comprises a plurality of collector electrode sections which are distributed at intervals along the second direction, and the interval between two adjacent collector electrode sections in the same collector electrode is used for isolating the collector electrode with the opposite polarity; wherein a portion of the first region in ohmic contact with each collector electrode segment in the first electrode is a contact region; a distance between the end of each contact area and the edge of the first area is a first distance along the second direction; a distance between the end of each current collecting electrode section in the second electrode and the edge of the first region is a second distance along the second direction; the first distance is less than the second distance.
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